1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * linux/fs/namei.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds /* 91da177e4SLinus Torvalds * Some corrections by tytso. 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 131da177e4SLinus Torvalds * lookup logic. 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 161da177e4SLinus Torvalds */ 171da177e4SLinus Torvalds 181da177e4SLinus Torvalds #include <linux/init.h> 19630d9c47SPaul Gortmaker #include <linux/export.h> 2044696908SDavid S. Miller #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/slab.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 235970e15dSJeff Layton #include <linux/filelock.h> 241da177e4SLinus Torvalds #include <linux/namei.h> 251da177e4SLinus Torvalds #include <linux/pagemap.h> 262d878178SMatthew Wilcox (Oracle) #include <linux/sched/mm.h> 270eeca283SRobert Love #include <linux/fsnotify.h> 281da177e4SLinus Torvalds #include <linux/personality.h> 291da177e4SLinus Torvalds #include <linux/security.h> 306146f0d5SMimi Zohar #include <linux/ima.h> 311da177e4SLinus Torvalds #include <linux/syscalls.h> 321da177e4SLinus Torvalds #include <linux/mount.h> 331da177e4SLinus Torvalds #include <linux/audit.h> 3416f7e0feSRandy Dunlap #include <linux/capability.h> 35834f2a4aSTrond Myklebust #include <linux/file.h> 365590ff0dSUlrich Drepper #include <linux/fcntl.h> 3708ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 385ad4e53bSAl Viro #include <linux/fs_struct.h> 39e77819e5SLinus Torvalds #include <linux/posix_acl.h> 4099d263d4SLinus Torvalds #include <linux/hash.h> 412a18da7aSGeorge Spelvin #include <linux/bitops.h> 42aeaa4a79SEric W. Biederman #include <linux/init_task.h> 437c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 441da177e4SLinus Torvalds 45e81e3f4dSEric Paris #include "internal.h" 46c7105365SAl Viro #include "mount.h" 47e81e3f4dSEric Paris 481da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 491da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 501da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 511da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 521da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 531da177e4SLinus Torvalds * 541da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 551da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 561da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 571da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 581da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 591da177e4SLinus Torvalds * the special cases of the former code. 601da177e4SLinus Torvalds * 611da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 621da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 631da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 641da177e4SLinus Torvalds * 651da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 661da177e4SLinus Torvalds * resolution to correspond with current state of the code. 671da177e4SLinus Torvalds * 681da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 691da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 701da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 711da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 721da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 731da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 741da177e4SLinus Torvalds */ 751da177e4SLinus Torvalds 761da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 771da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 781da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 791da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 801da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 811da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8225985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 831da177e4SLinus Torvalds * 841da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 851da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 861da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 871da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 881da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 891da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 901da177e4SLinus Torvalds * and in the old Linux semantics. 911da177e4SLinus Torvalds */ 921da177e4SLinus Torvalds 931da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 941da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 951da177e4SLinus Torvalds * 961da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 971da177e4SLinus Torvalds */ 981da177e4SLinus Torvalds 991da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 1001da177e4SLinus Torvalds * inside the path - always follow. 1011da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1021da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1031da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1041da177e4SLinus Torvalds * otherwise - don't follow. 1051da177e4SLinus Torvalds * (applied in that order). 1061da177e4SLinus Torvalds * 1071da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1081da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1091da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1101da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1111da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds /* 1141da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 115a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1161da177e4SLinus Torvalds * any extra contention... 1171da177e4SLinus Torvalds */ 1181da177e4SLinus Torvalds 1191da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1201da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1211da177e4SLinus Torvalds * kernel data space before using them.. 1221da177e4SLinus Torvalds * 1231da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1241da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1251da177e4SLinus Torvalds */ 1267950e385SJeff Layton 127fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12891a27b2aSJeff Layton 12951f39a1fSDavid Drysdale struct filename * 13091a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 13191a27b2aSJeff Layton { 13294b5d262SAl Viro struct filename *result; 1337950e385SJeff Layton char *kname; 13494b5d262SAl Viro int len; 1351da177e4SLinus Torvalds 1367ac86265SJeff Layton result = audit_reusename(filename); 1377ac86265SJeff Layton if (result) 1387ac86265SJeff Layton return result; 1397ac86265SJeff Layton 1407950e385SJeff Layton result = __getname(); 1413f9f0aa6SLinus Torvalds if (unlikely(!result)) 1424043cde8SEric Paris return ERR_PTR(-ENOMEM); 1431da177e4SLinus Torvalds 1447950e385SJeff Layton /* 1457950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1467950e385SJeff Layton * allocation 1477950e385SJeff Layton */ 148fd2f7cb5SAl Viro kname = (char *)result->iname; 14991a27b2aSJeff Layton result->name = kname; 1507950e385SJeff Layton 15194b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15291a27b2aSJeff Layton if (unlikely(len < 0)) { 15394b5d262SAl Viro __putname(result); 15494b5d262SAl Viro return ERR_PTR(len); 15591a27b2aSJeff Layton } 1563f9f0aa6SLinus Torvalds 1577950e385SJeff Layton /* 1587950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1597950e385SJeff Layton * separate struct filename so we can dedicate the entire 1607950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1617950e385SJeff Layton * userland. 1627950e385SJeff Layton */ 16394b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 164fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1657950e385SJeff Layton kname = (char *)result; 1667950e385SJeff Layton 167fd2f7cb5SAl Viro /* 168fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 169fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 170fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 171fd2f7cb5SAl Viro */ 172fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17394b5d262SAl Viro if (unlikely(!result)) { 17494b5d262SAl Viro __putname(kname); 17594b5d262SAl Viro return ERR_PTR(-ENOMEM); 1767950e385SJeff Layton } 1777950e385SJeff Layton result->name = kname; 17894b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17994b5d262SAl Viro if (unlikely(len < 0)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(len); 18394b5d262SAl Viro } 18494b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18594b5d262SAl Viro __putname(kname); 18694b5d262SAl Viro kfree(result); 18794b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18894b5d262SAl Viro } 1897950e385SJeff Layton } 1907950e385SJeff Layton 19194b5d262SAl Viro result->refcnt = 1; 1923f9f0aa6SLinus Torvalds /* The empty path is special. */ 1933f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1943f9f0aa6SLinus Torvalds if (empty) 1951fa1e7f6SAndy Whitcroft *empty = 1; 19694b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19794b5d262SAl Viro putname(result); 19894b5d262SAl Viro return ERR_PTR(-ENOENT); 1991da177e4SLinus Torvalds } 20094b5d262SAl Viro } 2017950e385SJeff Layton 2027950e385SJeff Layton result->uptr = filename; 203c4ad8f98SLinus Torvalds result->aname = NULL; 2041da177e4SLinus Torvalds audit_getname(result); 2051da177e4SLinus Torvalds return result; 2063f9f0aa6SLinus Torvalds } 2073f9f0aa6SLinus Torvalds 20891a27b2aSJeff Layton struct filename * 2098228e2c3SDmitry Kadashev getname_uflags(const char __user *filename, int uflags) 2108228e2c3SDmitry Kadashev { 2118228e2c3SDmitry Kadashev int flags = (uflags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0; 2128228e2c3SDmitry Kadashev 2138228e2c3SDmitry Kadashev return getname_flags(filename, flags, NULL); 2148228e2c3SDmitry Kadashev } 2158228e2c3SDmitry Kadashev 2168228e2c3SDmitry Kadashev struct filename * 21791a27b2aSJeff Layton getname(const char __user * filename) 218f52e0c11SAl Viro { 219f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 220f52e0c11SAl Viro } 221f52e0c11SAl Viro 222c4ad8f98SLinus Torvalds struct filename * 223c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 224c4ad8f98SLinus Torvalds { 225c4ad8f98SLinus Torvalds struct filename *result; 22608518549SPaul Moore int len = strlen(filename) + 1; 227c4ad8f98SLinus Torvalds 228c4ad8f98SLinus Torvalds result = __getname(); 229c4ad8f98SLinus Torvalds if (unlikely(!result)) 230c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 231c4ad8f98SLinus Torvalds 23208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 233fd2f7cb5SAl Viro result->name = (char *)result->iname; 23408518549SPaul Moore } else if (len <= PATH_MAX) { 23530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 23608518549SPaul Moore struct filename *tmp; 23708518549SPaul Moore 23830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 23908518549SPaul Moore if (unlikely(!tmp)) { 24008518549SPaul Moore __putname(result); 24108518549SPaul Moore return ERR_PTR(-ENOMEM); 24208518549SPaul Moore } 24308518549SPaul Moore tmp->name = (char *)result; 24408518549SPaul Moore result = tmp; 24508518549SPaul Moore } else { 24608518549SPaul Moore __putname(result); 24708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 24808518549SPaul Moore } 24908518549SPaul Moore memcpy((char *)result->name, filename, len); 250c4ad8f98SLinus Torvalds result->uptr = NULL; 251c4ad8f98SLinus Torvalds result->aname = NULL; 25255422d0bSPaul Moore result->refcnt = 1; 253fd3522fdSPaul Moore audit_getname(result); 254c4ad8f98SLinus Torvalds 255c4ad8f98SLinus Torvalds return result; 256c4ad8f98SLinus Torvalds } 25774d7970fSNamjae Jeon EXPORT_SYMBOL(getname_kernel); 258c4ad8f98SLinus Torvalds 25991a27b2aSJeff Layton void putname(struct filename *name) 2601da177e4SLinus Torvalds { 261ea47ab11SAl Viro if (IS_ERR(name)) 26291ef658fSDmitry Kadashev return; 26391ef658fSDmitry Kadashev 26455422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 26555422d0bSPaul Moore 26655422d0bSPaul Moore if (--name->refcnt > 0) 26755422d0bSPaul Moore return; 26855422d0bSPaul Moore 269fd2f7cb5SAl Viro if (name->name != name->iname) { 27055422d0bSPaul Moore __putname(name->name); 27155422d0bSPaul Moore kfree(name); 27255422d0bSPaul Moore } else 27355422d0bSPaul Moore __putname(name); 2741da177e4SLinus Torvalds } 27574d7970fSNamjae Jeon EXPORT_SYMBOL(putname); 2761da177e4SLinus Torvalds 27747291baaSChristian Brauner /** 27847291baaSChristian Brauner * check_acl - perform ACL permission checking 279700b7940SChristian Brauner * @idmap: idmap of the mount the inode was found from 28047291baaSChristian Brauner * @inode: inode to check permissions on 28147291baaSChristian Brauner * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...) 28247291baaSChristian Brauner * 28347291baaSChristian Brauner * This function performs the ACL permission checking. Since this function 28447291baaSChristian Brauner * retrieve POSIX acls it needs to know whether it is called from a blocking or 28547291baaSChristian Brauner * non-blocking context and thus cares about the MAY_NOT_BLOCK bit. 28647291baaSChristian Brauner * 287700b7940SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 288700b7940SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 289700b7940SChristian Brauner * care to map the inode according to @idmap before checking permissions. 29047291baaSChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 291700b7940SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 29247291baaSChristian Brauner */ 293700b7940SChristian Brauner static int check_acl(struct mnt_idmap *idmap, 29447291baaSChristian Brauner struct inode *inode, int mask) 295e77819e5SLinus Torvalds { 29684635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 297e77819e5SLinus Torvalds struct posix_acl *acl; 298e77819e5SLinus Torvalds 299e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 3003567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 3013567866bSAl Viro if (!acl) 302e77819e5SLinus Torvalds return -EAGAIN; 303cac2f8b8SChristian Brauner /* no ->get_inode_acl() calls in RCU mode... */ 304b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 305e77819e5SLinus Torvalds return -ECHILD; 306700b7940SChristian Brauner return posix_acl_permission(idmap, inode, acl, mask); 307e77819e5SLinus Torvalds } 308e77819e5SLinus Torvalds 309cac2f8b8SChristian Brauner acl = get_inode_acl(inode, ACL_TYPE_ACCESS); 3104e34e719SChristoph Hellwig if (IS_ERR(acl)) 3114e34e719SChristoph Hellwig return PTR_ERR(acl); 312e77819e5SLinus Torvalds if (acl) { 313700b7940SChristian Brauner int error = posix_acl_permission(idmap, inode, acl, mask); 314e77819e5SLinus Torvalds posix_acl_release(acl); 315e77819e5SLinus Torvalds return error; 316e77819e5SLinus Torvalds } 31784635d68SLinus Torvalds #endif 318e77819e5SLinus Torvalds 319e77819e5SLinus Torvalds return -EAGAIN; 320e77819e5SLinus Torvalds } 321e77819e5SLinus Torvalds 32247291baaSChristian Brauner /** 32347291baaSChristian Brauner * acl_permission_check - perform basic UNIX permission checking 324700b7940SChristian Brauner * @idmap: idmap of the mount the inode was found from 32547291baaSChristian Brauner * @inode: inode to check permissions on 32647291baaSChristian Brauner * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...) 3275fc475b7SLinus Torvalds * 32847291baaSChristian Brauner * This function performs the basic UNIX permission checking. Since this 32947291baaSChristian Brauner * function may retrieve POSIX acls it needs to know whether it is called from a 33047291baaSChristian Brauner * blocking or non-blocking context and thus cares about the MAY_NOT_BLOCK bit. 33147291baaSChristian Brauner * 332700b7940SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 333700b7940SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 334700b7940SChristian Brauner * care to map the inode according to @idmap before checking permissions. 33547291baaSChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 336700b7940SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 3375909ccaaSLinus Torvalds */ 338700b7940SChristian Brauner static int acl_permission_check(struct mnt_idmap *idmap, 33947291baaSChristian Brauner struct inode *inode, int mask) 3405909ccaaSLinus Torvalds { 34126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 342a2bd096fSChristian Brauner vfsuid_t vfsuid; 3435909ccaaSLinus Torvalds 3445fc475b7SLinus Torvalds /* Are we the owner? If so, ACL's don't matter */ 345e67fe633SChristian Brauner vfsuid = i_uid_into_vfsuid(idmap, inode); 346a2bd096fSChristian Brauner if (likely(vfsuid_eq_kuid(vfsuid, current_fsuid()))) { 3475fc475b7SLinus Torvalds mask &= 7; 3485909ccaaSLinus Torvalds mode >>= 6; 3495fc475b7SLinus Torvalds return (mask & ~mode) ? -EACCES : 0; 3505fc475b7SLinus Torvalds } 3515fc475b7SLinus Torvalds 3525fc475b7SLinus Torvalds /* Do we have ACL's? */ 353e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 354700b7940SChristian Brauner int error = check_acl(idmap, inode, mask); 3555909ccaaSLinus Torvalds if (error != -EAGAIN) 3565909ccaaSLinus Torvalds return error; 3575909ccaaSLinus Torvalds } 3585909ccaaSLinus Torvalds 3595fc475b7SLinus Torvalds /* Only RWX matters for group/other mode bits */ 3605fc475b7SLinus Torvalds mask &= 7; 3615fc475b7SLinus Torvalds 3625fc475b7SLinus Torvalds /* 3635fc475b7SLinus Torvalds * Are the group permissions different from 3645fc475b7SLinus Torvalds * the other permissions in the bits we care 3655fc475b7SLinus Torvalds * about? Need to check group ownership if so. 3665fc475b7SLinus Torvalds */ 3675fc475b7SLinus Torvalds if (mask & (mode ^ (mode >> 3))) { 368e67fe633SChristian Brauner vfsgid_t vfsgid = i_gid_into_vfsgid(idmap, inode); 369a2bd096fSChristian Brauner if (vfsgid_in_group_p(vfsgid)) 3705909ccaaSLinus Torvalds mode >>= 3; 3715909ccaaSLinus Torvalds } 3725909ccaaSLinus Torvalds 3735fc475b7SLinus Torvalds /* Bits in 'mode' clear that we require? */ 3745fc475b7SLinus Torvalds return (mask & ~mode) ? -EACCES : 0; 3755909ccaaSLinus Torvalds } 3761da177e4SLinus Torvalds 3771da177e4SLinus Torvalds /** 3781da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3794609e1f1SChristian Brauner * @idmap: idmap of the mount the inode was found from 3801da177e4SLinus Torvalds * @inode: inode to check access rights for 3815fc475b7SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, 3825fc475b7SLinus Torvalds * %MAY_NOT_BLOCK ...) 3831da177e4SLinus Torvalds * 3841da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3851da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3861da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 387b74c79e9SNick Piggin * are used for other things. 388b74c79e9SNick Piggin * 389b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 390b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 391b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 39247291baaSChristian Brauner * 3934609e1f1SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 3944609e1f1SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 3954609e1f1SChristian Brauner * care to map the inode according to @idmap before checking permissions. 39647291baaSChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 3974609e1f1SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 3981da177e4SLinus Torvalds */ 3994609e1f1SChristian Brauner int generic_permission(struct mnt_idmap *idmap, struct inode *inode, 40047291baaSChristian Brauner int mask) 4011da177e4SLinus Torvalds { 4025909ccaaSLinus Torvalds int ret; 4031da177e4SLinus Torvalds 4041da177e4SLinus Torvalds /* 405948409c7SAndreas Gruenbacher * Do the basic permission checks. 4061da177e4SLinus Torvalds */ 407700b7940SChristian Brauner ret = acl_permission_check(idmap, inode, mask); 4085909ccaaSLinus Torvalds if (ret != -EACCES) 4095909ccaaSLinus Torvalds return ret; 4101da177e4SLinus Torvalds 411d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 412d594e7ecSAl Viro /* DACs are overridable for directories */ 413d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 4149452e93eSChristian Brauner if (capable_wrt_inode_uidgid(idmap, inode, 41523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 416d594e7ecSAl Viro return 0; 4179452e93eSChristian Brauner if (capable_wrt_inode_uidgid(idmap, inode, 4180558c1bfSChristian Brauner CAP_DAC_OVERRIDE)) 4191da177e4SLinus Torvalds return 0; 4202a4c2242SStephen Smalley return -EACCES; 4212a4c2242SStephen Smalley } 4221da177e4SLinus Torvalds 4231da177e4SLinus Torvalds /* 4241da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 4251da177e4SLinus Torvalds */ 4267ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 427d594e7ecSAl Viro if (mask == MAY_READ) 4289452e93eSChristian Brauner if (capable_wrt_inode_uidgid(idmap, inode, 4290558c1bfSChristian Brauner CAP_DAC_READ_SEARCH)) 4301da177e4SLinus Torvalds return 0; 4312a4c2242SStephen Smalley /* 4322a4c2242SStephen Smalley * Read/write DACs are always overridable. 4332a4c2242SStephen Smalley * Executable DACs are overridable when there is 4342a4c2242SStephen Smalley * at least one exec bit set. 4352a4c2242SStephen Smalley */ 4362a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 4379452e93eSChristian Brauner if (capable_wrt_inode_uidgid(idmap, inode, 4380558c1bfSChristian Brauner CAP_DAC_OVERRIDE)) 4392a4c2242SStephen Smalley return 0; 4401da177e4SLinus Torvalds 4411da177e4SLinus Torvalds return -EACCES; 4421da177e4SLinus Torvalds } 4434d359507SAl Viro EXPORT_SYMBOL(generic_permission); 4441da177e4SLinus Torvalds 44547291baaSChristian Brauner /** 44647291baaSChristian Brauner * do_inode_permission - UNIX permission checking 4474609e1f1SChristian Brauner * @idmap: idmap of the mount the inode was found from 44847291baaSChristian Brauner * @inode: inode to check permissions on 44947291baaSChristian Brauner * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...) 45047291baaSChristian Brauner * 4513ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 4523ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 4533ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 4543ddcd056SLinus Torvalds * permission function, use the fast case". 4553ddcd056SLinus Torvalds */ 4564609e1f1SChristian Brauner static inline int do_inode_permission(struct mnt_idmap *idmap, 45747291baaSChristian Brauner struct inode *inode, int mask) 4583ddcd056SLinus Torvalds { 4593ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 4603ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 4614609e1f1SChristian Brauner return inode->i_op->permission(idmap, inode, mask); 4623ddcd056SLinus Torvalds 4633ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 4643ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 4653ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 4663ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 4673ddcd056SLinus Torvalds } 4684609e1f1SChristian Brauner return generic_permission(idmap, inode, mask); 4693ddcd056SLinus Torvalds } 4703ddcd056SLinus Torvalds 471cb23beb5SChristoph Hellwig /** 4720bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4730bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 47455852635SRandy Dunlap * @inode: Inode to check permission on 4750bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4760bdaea90SDavid Howells * 4770bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4780bdaea90SDavid Howells */ 4790bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4800bdaea90SDavid Howells { 4810bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4820bdaea90SDavid Howells umode_t mode = inode->i_mode; 4830bdaea90SDavid Howells 4840bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 485bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4860bdaea90SDavid Howells return -EROFS; 4870bdaea90SDavid Howells } 4880bdaea90SDavid Howells return 0; 4890bdaea90SDavid Howells } 4900bdaea90SDavid Howells 4910bdaea90SDavid Howells /** 4920bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4934609e1f1SChristian Brauner * @idmap: idmap of the mount the inode was found from 4940bdaea90SDavid Howells * @inode: Inode to check permission on 4950bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4960bdaea90SDavid Howells * 4970bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4980bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4990bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 5000bdaea90SDavid Howells * 5010bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 5020bdaea90SDavid Howells */ 5034609e1f1SChristian Brauner int inode_permission(struct mnt_idmap *idmap, 50447291baaSChristian Brauner struct inode *inode, int mask) 5050bdaea90SDavid Howells { 5060bdaea90SDavid Howells int retval; 5070bdaea90SDavid Howells 5080bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 5090bdaea90SDavid Howells if (retval) 5100bdaea90SDavid Howells return retval; 5114bfd054aSEric Biggers 5124bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 5134bfd054aSEric Biggers /* 5144bfd054aSEric Biggers * Nobody gets write access to an immutable file. 5154bfd054aSEric Biggers */ 5164bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 5174bfd054aSEric Biggers return -EPERM; 5184bfd054aSEric Biggers 5194bfd054aSEric Biggers /* 5204bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 5214bfd054aSEric Biggers * written back improperly if their true value is unknown 5224bfd054aSEric Biggers * to the vfs. 5234bfd054aSEric Biggers */ 5244609e1f1SChristian Brauner if (HAS_UNMAPPED_ID(idmap, inode)) 5254bfd054aSEric Biggers return -EACCES; 5264bfd054aSEric Biggers } 5274bfd054aSEric Biggers 5284609e1f1SChristian Brauner retval = do_inode_permission(idmap, inode, mask); 5294bfd054aSEric Biggers if (retval) 5304bfd054aSEric Biggers return retval; 5314bfd054aSEric Biggers 5324bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 5334bfd054aSEric Biggers if (retval) 5344bfd054aSEric Biggers return retval; 5354bfd054aSEric Biggers 5364bfd054aSEric Biggers return security_inode_permission(inode, mask); 5370bdaea90SDavid Howells } 5384d359507SAl Viro EXPORT_SYMBOL(inode_permission); 5390bdaea90SDavid Howells 5400bdaea90SDavid Howells /** 5415dd784d0SJan Blunck * path_get - get a reference to a path 5425dd784d0SJan Blunck * @path: path to get the reference to 5435dd784d0SJan Blunck * 5445dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 5455dd784d0SJan Blunck */ 546dcf787f3SAl Viro void path_get(const struct path *path) 5475dd784d0SJan Blunck { 5485dd784d0SJan Blunck mntget(path->mnt); 5495dd784d0SJan Blunck dget(path->dentry); 5505dd784d0SJan Blunck } 5515dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 5525dd784d0SJan Blunck 5535dd784d0SJan Blunck /** 5541d957f9bSJan Blunck * path_put - put a reference to a path 5551d957f9bSJan Blunck * @path: path to put the reference to 5561d957f9bSJan Blunck * 5571d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 5581d957f9bSJan Blunck */ 559dcf787f3SAl Viro void path_put(const struct path *path) 5601da177e4SLinus Torvalds { 5611d957f9bSJan Blunck dput(path->dentry); 5621d957f9bSJan Blunck mntput(path->mnt); 5631da177e4SLinus Torvalds } 5641d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 5651da177e4SLinus Torvalds 566894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 5671f55a6ecSAl Viro struct nameidata { 5681f55a6ecSAl Viro struct path path; 5691f55a6ecSAl Viro struct qstr last; 5701f55a6ecSAl Viro struct path root; 5711f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 572bcba1e7dSAl Viro unsigned int flags, state; 57303fa86e9SAl Viro unsigned seq, next_seq, m_seq, r_seq; 5741f55a6ecSAl Viro int last_type; 5751f55a6ecSAl Viro unsigned depth; 576756daf26SNeilBrown int total_link_count; 577697fc6caSAl Viro struct saved { 578697fc6caSAl Viro struct path link; 579fceef393SAl Viro struct delayed_call done; 580697fc6caSAl Viro const char *name; 5810450b2d1SAl Viro unsigned seq; 582894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5839883d185SAl Viro struct filename *name; 5849883d185SAl Viro struct nameidata *saved; 5859883d185SAl Viro unsigned root_seq; 5869883d185SAl Viro int dfd; 587a2bd096fSChristian Brauner vfsuid_t dir_vfsuid; 5880f705953SAl Viro umode_t dir_mode; 5893859a271SKees Cook } __randomize_layout; 5901f55a6ecSAl Viro 591bcba1e7dSAl Viro #define ND_ROOT_PRESET 1 592bcba1e7dSAl Viro #define ND_ROOT_GRABBED 2 593bcba1e7dSAl Viro #define ND_JUMPED 4 594bcba1e7dSAl Viro 59506422964SAl Viro static void __set_nameidata(struct nameidata *p, int dfd, struct filename *name) 596894bc8c4SAl Viro { 597756daf26SNeilBrown struct nameidata *old = current->nameidata; 598756daf26SNeilBrown p->stack = p->internal; 5997962c7d1SAl Viro p->depth = 0; 600c8a53ee5SAl Viro p->dfd = dfd; 601c8a53ee5SAl Viro p->name = name; 6027d01ef75SAl Viro p->path.mnt = NULL; 6037d01ef75SAl Viro p->path.dentry = NULL; 604756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 6059883d185SAl Viro p->saved = old; 606756daf26SNeilBrown current->nameidata = p; 607894bc8c4SAl Viro } 608894bc8c4SAl Viro 60906422964SAl Viro static inline void set_nameidata(struct nameidata *p, int dfd, struct filename *name, 61006422964SAl Viro const struct path *root) 61106422964SAl Viro { 61206422964SAl Viro __set_nameidata(p, dfd, name); 61306422964SAl Viro p->state = 0; 61406422964SAl Viro if (unlikely(root)) { 61506422964SAl Viro p->state = ND_ROOT_PRESET; 61606422964SAl Viro p->root = *root; 61706422964SAl Viro } 61806422964SAl Viro } 61906422964SAl Viro 6209883d185SAl Viro static void restore_nameidata(void) 621894bc8c4SAl Viro { 6229883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 623756daf26SNeilBrown 624756daf26SNeilBrown current->nameidata = old; 625756daf26SNeilBrown if (old) 626756daf26SNeilBrown old->total_link_count = now->total_link_count; 627e1a63bbcSAl Viro if (now->stack != now->internal) 628756daf26SNeilBrown kfree(now->stack); 629894bc8c4SAl Viro } 630894bc8c4SAl Viro 63160ef60c7SAl Viro static bool nd_alloc_stack(struct nameidata *nd) 632894bc8c4SAl Viro { 633bc40aee0SAl Viro struct saved *p; 634bc40aee0SAl Viro 6356da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 63660ef60c7SAl Viro nd->flags & LOOKUP_RCU ? GFP_ATOMIC : GFP_KERNEL); 637bc40aee0SAl Viro if (unlikely(!p)) 63860ef60c7SAl Viro return false; 639894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 640894bc8c4SAl Viro nd->stack = p; 64160ef60c7SAl Viro return true; 642894bc8c4SAl Viro } 643894bc8c4SAl Viro 644397d425dSEric W. Biederman /** 6456b03f7edSAl Viro * path_connected - Verify that a dentry is below mnt.mnt_root 646*35931eb3SMatthew Wilcox (Oracle) * @mnt: The mountpoint to check. 647*35931eb3SMatthew Wilcox (Oracle) * @dentry: The dentry to check. 648397d425dSEric W. Biederman * 649397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 650397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 651397d425dSEric W. Biederman */ 6526b03f7edSAl Viro static bool path_connected(struct vfsmount *mnt, struct dentry *dentry) 653397d425dSEric W. Biederman { 65495dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 655397d425dSEric W. Biederman 656402dd2cfSChristoph Hellwig /* Bind mounts can have disconnected paths */ 657402dd2cfSChristoph Hellwig if (mnt->mnt_root == sb->s_root) 658397d425dSEric W. Biederman return true; 659397d425dSEric W. Biederman 6606b03f7edSAl Viro return is_subdir(dentry, mnt->mnt_root); 661397d425dSEric W. Biederman } 662397d425dSEric W. Biederman 6637973387aSAl Viro static void drop_links(struct nameidata *nd) 6647973387aSAl Viro { 6657973387aSAl Viro int i = nd->depth; 6667973387aSAl Viro while (i--) { 6677973387aSAl Viro struct saved *last = nd->stack + i; 668fceef393SAl Viro do_delayed_call(&last->done); 669fceef393SAl Viro clear_delayed_call(&last->done); 6707973387aSAl Viro } 6717973387aSAl Viro } 6727973387aSAl Viro 6736e180327SAl Viro static void leave_rcu(struct nameidata *nd) 6746e180327SAl Viro { 6756e180327SAl Viro nd->flags &= ~LOOKUP_RCU; 67603fa86e9SAl Viro nd->seq = nd->next_seq = 0; 6776e180327SAl Viro rcu_read_unlock(); 6786e180327SAl Viro } 6796e180327SAl Viro 6807973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6817973387aSAl Viro { 6827973387aSAl Viro drop_links(nd); 6837973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6847973387aSAl Viro int i; 6857973387aSAl Viro path_put(&nd->path); 6867973387aSAl Viro for (i = 0; i < nd->depth; i++) 6877973387aSAl Viro path_put(&nd->stack[i].link); 688bcba1e7dSAl Viro if (nd->state & ND_ROOT_GRABBED) { 689102b8af2SAl Viro path_put(&nd->root); 690bcba1e7dSAl Viro nd->state &= ~ND_ROOT_GRABBED; 691102b8af2SAl Viro } 6927973387aSAl Viro } else { 6936e180327SAl Viro leave_rcu(nd); 6947973387aSAl Viro } 6957973387aSAl Viro nd->depth = 0; 6967d01ef75SAl Viro nd->path.mnt = NULL; 6977d01ef75SAl Viro nd->path.dentry = NULL; 6987973387aSAl Viro } 6997973387aSAl Viro 7007973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 7012aa38470SAl Viro static bool __legitimize_path(struct path *path, unsigned seq, unsigned mseq) 7027973387aSAl Viro { 7032aa38470SAl Viro int res = __legitimize_mnt(path->mnt, mseq); 7047973387aSAl Viro if (unlikely(res)) { 7057973387aSAl Viro if (res > 0) 7067973387aSAl Viro path->mnt = NULL; 7077973387aSAl Viro path->dentry = NULL; 7087973387aSAl Viro return false; 7097973387aSAl Viro } 7107973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 7117973387aSAl Viro path->dentry = NULL; 7127973387aSAl Viro return false; 7137973387aSAl Viro } 7147973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 7157973387aSAl Viro } 7167973387aSAl Viro 7172aa38470SAl Viro static inline bool legitimize_path(struct nameidata *nd, 7182aa38470SAl Viro struct path *path, unsigned seq) 7192aa38470SAl Viro { 7205bd73286SAl Viro return __legitimize_path(path, seq, nd->m_seq); 7212aa38470SAl Viro } 7222aa38470SAl Viro 7237973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 7247973387aSAl Viro { 7257973387aSAl Viro int i; 726eacd9aa8SAl Viro if (unlikely(nd->flags & LOOKUP_CACHED)) { 727eacd9aa8SAl Viro drop_links(nd); 728eacd9aa8SAl Viro nd->depth = 0; 729eacd9aa8SAl Viro return false; 730eacd9aa8SAl Viro } 7317973387aSAl Viro for (i = 0; i < nd->depth; i++) { 7327973387aSAl Viro struct saved *last = nd->stack + i; 7337973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 7347973387aSAl Viro drop_links(nd); 7357973387aSAl Viro nd->depth = i + 1; 7367973387aSAl Viro return false; 7377973387aSAl Viro } 7387973387aSAl Viro } 7397973387aSAl Viro return true; 7407973387aSAl Viro } 7417973387aSAl Viro 742ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 743ee594bffSAl Viro { 744adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 745bcba1e7dSAl Viro if (!nd->root.mnt || (nd->state & ND_ROOT_PRESET)) 746ee594bffSAl Viro return true; 747bcba1e7dSAl Viro nd->state |= ND_ROOT_GRABBED; 748ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 749ee594bffSAl Viro } 750ee594bffSAl Viro 75119660af7SAl Viro /* 75231e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 75319660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 75419660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 75557e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 75619660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 75719660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 75819660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 75919660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 76031e6b01fSNick Piggin */ 76131e6b01fSNick Piggin 76231e6b01fSNick Piggin /** 763e36cffedSJens Axboe * try_to_unlazy - try to switch to ref-walk mode. 76419660af7SAl Viro * @nd: nameidata pathwalk data 765e36cffedSJens Axboe * Returns: true on success, false on failure 76631e6b01fSNick Piggin * 767e36cffedSJens Axboe * try_to_unlazy attempts to legitimize the current nd->path and nd->root 7684675ac39SAl Viro * for ref-walk mode. 7694675ac39SAl Viro * Must be called from rcu-walk context. 770e36cffedSJens Axboe * Nothing should touch nameidata between try_to_unlazy() failure and 7717973387aSAl Viro * terminate_walk(). 77231e6b01fSNick Piggin */ 773e36cffedSJens Axboe static bool try_to_unlazy(struct nameidata *nd) 77431e6b01fSNick Piggin { 77531e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 77631e6b01fSNick Piggin 77731e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 778e5c832d5SLinus Torvalds 7797973387aSAl Viro if (unlikely(!legitimize_links(nd))) 7804675ac39SAl Viro goto out1; 78184a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 78284a2bd39SAl Viro goto out; 783ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 7844675ac39SAl Viro goto out; 7856e180327SAl Viro leave_rcu(nd); 7864675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 787e36cffedSJens Axboe return true; 7884675ac39SAl Viro 78984a2bd39SAl Viro out1: 7904675ac39SAl Viro nd->path.mnt = NULL; 7914675ac39SAl Viro nd->path.dentry = NULL; 7924675ac39SAl Viro out: 7936e180327SAl Viro leave_rcu(nd); 794e36cffedSJens Axboe return false; 7954675ac39SAl Viro } 7964675ac39SAl Viro 7974675ac39SAl Viro /** 798ae66db45SAl Viro * try_to_unlazy_next - try to switch to ref-walk mode. 7994675ac39SAl Viro * @nd: nameidata pathwalk data 800ae66db45SAl Viro * @dentry: next dentry to step into 801ae66db45SAl Viro * Returns: true on success, false on failure 8024675ac39SAl Viro * 80330476f7eSTom Rix * Similar to try_to_unlazy(), but here we have the next dentry already 804ae66db45SAl Viro * picked by rcu-walk and want to legitimize that in addition to the current 805ae66db45SAl Viro * nd->path and nd->root for ref-walk mode. Must be called from rcu-walk context. 806ae66db45SAl Viro * Nothing should touch nameidata between try_to_unlazy_next() failure and 8074675ac39SAl Viro * terminate_walk(). 8084675ac39SAl Viro */ 80903fa86e9SAl Viro static bool try_to_unlazy_next(struct nameidata *nd, struct dentry *dentry) 8104675ac39SAl Viro { 8117e4745a0SAl Viro int res; 8124675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 8134675ac39SAl Viro 8144675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 8154675ac39SAl Viro goto out2; 8167e4745a0SAl Viro res = __legitimize_mnt(nd->path.mnt, nd->m_seq); 8177e4745a0SAl Viro if (unlikely(res)) { 8187e4745a0SAl Viro if (res > 0) 8197973387aSAl Viro goto out2; 8207e4745a0SAl Viro goto out1; 8217e4745a0SAl Viro } 8224675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 8237973387aSAl Viro goto out1; 82448a066e7SAl Viro 82515570086SLinus Torvalds /* 8264675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 8274675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 8284675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 8294675ac39SAl Viro * number of the parent after we got the child sequence number. So we 8304675ac39SAl Viro * know the parent must still be valid if the child sequence number is 83115570086SLinus Torvalds */ 8324675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 833e5c832d5SLinus Torvalds goto out; 83403fa86e9SAl Viro if (read_seqcount_retry(&dentry->d_seq, nd->next_seq)) 83584a2bd39SAl Viro goto out_dput; 836e5c832d5SLinus Torvalds /* 837e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 838e5c832d5SLinus Torvalds * still valid and get it if required. 839e5c832d5SLinus Torvalds */ 84084a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 84184a2bd39SAl Viro goto out_dput; 8426e180327SAl Viro leave_rcu(nd); 843ae66db45SAl Viro return true; 84419660af7SAl Viro 8457973387aSAl Viro out2: 8467973387aSAl Viro nd->path.mnt = NULL; 8477973387aSAl Viro out1: 8487973387aSAl Viro nd->path.dentry = NULL; 849e5c832d5SLinus Torvalds out: 8506e180327SAl Viro leave_rcu(nd); 851ae66db45SAl Viro return false; 85284a2bd39SAl Viro out_dput: 8536e180327SAl Viro leave_rcu(nd); 85484a2bd39SAl Viro dput(dentry); 855ae66db45SAl Viro return false; 85631e6b01fSNick Piggin } 85731e6b01fSNick Piggin 8584ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 85934286d66SNick Piggin { 860a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 8614ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 862a89f8337SAl Viro else 863a89f8337SAl Viro return 1; 86434286d66SNick Piggin } 86534286d66SNick Piggin 8669f1fafeeSAl Viro /** 8679f1fafeeSAl Viro * complete_walk - successful completion of path walk 8689f1fafeeSAl Viro * @nd: pointer nameidata 86939159de2SJeff Layton * 8709f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 8719f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 8729f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 8739f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 8749f1fafeeSAl Viro * need to drop nd->path. 87539159de2SJeff Layton */ 8769f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 87739159de2SJeff Layton { 87816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 87939159de2SJeff Layton int status; 88039159de2SJeff Layton 8819f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 882adb21d2bSAleksa Sarai /* 883adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 884adb21d2bSAleksa Sarai * externally-managed nd->root. 885adb21d2bSAleksa Sarai */ 886bcba1e7dSAl Viro if (!(nd->state & ND_ROOT_PRESET)) 887bcba1e7dSAl Viro if (!(nd->flags & LOOKUP_IS_SCOPED)) 8889f1fafeeSAl Viro nd->root.mnt = NULL; 8896c6ec2b0SJens Axboe nd->flags &= ~LOOKUP_CACHED; 890e36cffedSJens Axboe if (!try_to_unlazy(nd)) 89148a066e7SAl Viro return -ECHILD; 89248a066e7SAl Viro } 8939f1fafeeSAl Viro 894adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 895adb21d2bSAleksa Sarai /* 896adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 897adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 898adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 899adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 900adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 901adb21d2bSAleksa Sarai * 902adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 903adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 904adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 905adb21d2bSAleksa Sarai * requested root to userspace. 906adb21d2bSAleksa Sarai * 907adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 908adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 909adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 910adb21d2bSAleksa Sarai */ 911adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 912adb21d2bSAleksa Sarai return -EXDEV; 913adb21d2bSAleksa Sarai } 914adb21d2bSAleksa Sarai 915bcba1e7dSAl Viro if (likely(!(nd->state & ND_JUMPED))) 91639159de2SJeff Layton return 0; 91739159de2SJeff Layton 918ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 91916c2cd71SAl Viro return 0; 92016c2cd71SAl Viro 921ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 92239159de2SJeff Layton if (status > 0) 92339159de2SJeff Layton return 0; 92439159de2SJeff Layton 92516c2cd71SAl Viro if (!status) 92639159de2SJeff Layton status = -ESTALE; 92716c2cd71SAl Viro 92839159de2SJeff Layton return status; 92939159de2SJeff Layton } 93039159de2SJeff Layton 931740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 9322a737871SAl Viro { 93331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 9349e6697e2SAl Viro 935adb21d2bSAleksa Sarai /* 936adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 937adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 938adb21d2bSAleksa Sarai * from the dirfd. 939adb21d2bSAleksa Sarai */ 940adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 941adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 942adb21d2bSAleksa Sarai 9439e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 9448f47a016SAl Viro unsigned seq; 945c28cc364SNick Piggin 946c28cc364SNick Piggin do { 947c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 94831e6b01fSNick Piggin nd->root = fs->root; 9498f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 950c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 9519e6697e2SAl Viro } else { 9529e6697e2SAl Viro get_fs_root(fs, &nd->root); 953bcba1e7dSAl Viro nd->state |= ND_ROOT_GRABBED; 9549e6697e2SAl Viro } 955740a1678SAleksa Sarai return 0; 95631e6b01fSNick Piggin } 95731e6b01fSNick Piggin 958248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 959248fb5b9SAl Viro { 960adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 961adb21d2bSAleksa Sarai return -EXDEV; 96272ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 96372ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 96472ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 96572ba2929SAleksa Sarai return -EXDEV; 96672ba2929SAleksa Sarai } 967740a1678SAleksa Sarai if (!nd->root.mnt) { 968740a1678SAleksa Sarai int error = set_root(nd); 969740a1678SAleksa Sarai if (error) 970740a1678SAleksa Sarai return error; 971740a1678SAleksa Sarai } 972248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 973248fb5b9SAl Viro struct dentry *d; 974248fb5b9SAl Viro nd->path = nd->root; 975248fb5b9SAl Viro d = nd->path.dentry; 976248fb5b9SAl Viro nd->inode = d->d_inode; 977248fb5b9SAl Viro nd->seq = nd->root_seq; 97882ef0698SAl Viro if (read_seqcount_retry(&d->d_seq, nd->seq)) 979248fb5b9SAl Viro return -ECHILD; 980248fb5b9SAl Viro } else { 981248fb5b9SAl Viro path_put(&nd->path); 982248fb5b9SAl Viro nd->path = nd->root; 983248fb5b9SAl Viro path_get(&nd->path); 984248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 985248fb5b9SAl Viro } 986bcba1e7dSAl Viro nd->state |= ND_JUMPED; 987248fb5b9SAl Viro return 0; 988248fb5b9SAl Viro } 989248fb5b9SAl Viro 990b5fb63c1SChristoph Hellwig /* 9916b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 992b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 993b5fb63c1SChristoph Hellwig */ 994ea4af4aaSAl Viro int nd_jump_link(const struct path *path) 995b5fb63c1SChristoph Hellwig { 9964b99d499SAleksa Sarai int error = -ELOOP; 9976e77137bSAl Viro struct nameidata *nd = current->nameidata; 998b5fb63c1SChristoph Hellwig 9994b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 10004b99d499SAleksa Sarai goto err; 10014b99d499SAleksa Sarai 100272ba2929SAleksa Sarai error = -EXDEV; 100372ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 100472ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 100572ba2929SAleksa Sarai goto err; 100672ba2929SAleksa Sarai } 1007adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 1008adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 1009adb21d2bSAleksa Sarai goto err; 101072ba2929SAleksa Sarai 10114b99d499SAleksa Sarai path_put(&nd->path); 1012b5fb63c1SChristoph Hellwig nd->path = *path; 1013b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 1014bcba1e7dSAl Viro nd->state |= ND_JUMPED; 10151bc82070SAleksa Sarai return 0; 10164b99d499SAleksa Sarai 10174b99d499SAleksa Sarai err: 10184b99d499SAleksa Sarai path_put(path); 10194b99d499SAleksa Sarai return error; 1020b5fb63c1SChristoph Hellwig } 1021b5fb63c1SChristoph Hellwig 1022b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 1023574197e0SAl Viro { 102421c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 1025fceef393SAl Viro do_delayed_call(&last->done); 10266548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 1027b9ff4429SAl Viro path_put(&last->link); 1028574197e0SAl Viro } 1029574197e0SAl Viro 10309c011be1SLuis Chamberlain static int sysctl_protected_symlinks __read_mostly; 10319c011be1SLuis Chamberlain static int sysctl_protected_hardlinks __read_mostly; 10329c011be1SLuis Chamberlain static int sysctl_protected_fifos __read_mostly; 10339c011be1SLuis Chamberlain static int sysctl_protected_regular __read_mostly; 10349c011be1SLuis Chamberlain 10359c011be1SLuis Chamberlain #ifdef CONFIG_SYSCTL 10369c011be1SLuis Chamberlain static struct ctl_table namei_sysctls[] = { 10379c011be1SLuis Chamberlain { 10389c011be1SLuis Chamberlain .procname = "protected_symlinks", 10399c011be1SLuis Chamberlain .data = &sysctl_protected_symlinks, 10409c011be1SLuis Chamberlain .maxlen = sizeof(int), 1041c7031c14SJulius Hemanth Pitti .mode = 0644, 10429c011be1SLuis Chamberlain .proc_handler = proc_dointvec_minmax, 10439c011be1SLuis Chamberlain .extra1 = SYSCTL_ZERO, 10449c011be1SLuis Chamberlain .extra2 = SYSCTL_ONE, 10459c011be1SLuis Chamberlain }, 10469c011be1SLuis Chamberlain { 10479c011be1SLuis Chamberlain .procname = "protected_hardlinks", 10489c011be1SLuis Chamberlain .data = &sysctl_protected_hardlinks, 10499c011be1SLuis Chamberlain .maxlen = sizeof(int), 1050c7031c14SJulius Hemanth Pitti .mode = 0644, 10519c011be1SLuis Chamberlain .proc_handler = proc_dointvec_minmax, 10529c011be1SLuis Chamberlain .extra1 = SYSCTL_ZERO, 10539c011be1SLuis Chamberlain .extra2 = SYSCTL_ONE, 10549c011be1SLuis Chamberlain }, 10559c011be1SLuis Chamberlain { 10569c011be1SLuis Chamberlain .procname = "protected_fifos", 10579c011be1SLuis Chamberlain .data = &sysctl_protected_fifos, 10589c011be1SLuis Chamberlain .maxlen = sizeof(int), 1059c7031c14SJulius Hemanth Pitti .mode = 0644, 10609c011be1SLuis Chamberlain .proc_handler = proc_dointvec_minmax, 10619c011be1SLuis Chamberlain .extra1 = SYSCTL_ZERO, 10629c011be1SLuis Chamberlain .extra2 = SYSCTL_TWO, 10639c011be1SLuis Chamberlain }, 10649c011be1SLuis Chamberlain { 10659c011be1SLuis Chamberlain .procname = "protected_regular", 10669c011be1SLuis Chamberlain .data = &sysctl_protected_regular, 10679c011be1SLuis Chamberlain .maxlen = sizeof(int), 1068c7031c14SJulius Hemanth Pitti .mode = 0644, 10699c011be1SLuis Chamberlain .proc_handler = proc_dointvec_minmax, 10709c011be1SLuis Chamberlain .extra1 = SYSCTL_ZERO, 10719c011be1SLuis Chamberlain .extra2 = SYSCTL_TWO, 10729c011be1SLuis Chamberlain }, 10739c011be1SLuis Chamberlain { } 10749c011be1SLuis Chamberlain }; 10759c011be1SLuis Chamberlain 10769c011be1SLuis Chamberlain static int __init init_fs_namei_sysctls(void) 10779c011be1SLuis Chamberlain { 10789c011be1SLuis Chamberlain register_sysctl_init("fs", namei_sysctls); 10799c011be1SLuis Chamberlain return 0; 10809c011be1SLuis Chamberlain } 10819c011be1SLuis Chamberlain fs_initcall(init_fs_namei_sysctls); 10829c011be1SLuis Chamberlain 10839c011be1SLuis Chamberlain #endif /* CONFIG_SYSCTL */ 1084800179c9SKees Cook 1085800179c9SKees Cook /** 1086800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 108755852635SRandy Dunlap * @nd: nameidata pathwalk data 1088*35931eb3SMatthew Wilcox (Oracle) * @inode: Used for idmapping. 1089800179c9SKees Cook * 1090800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 1091800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 1092800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 1093800179c9SKees Cook * processes from failing races against path names that may change out 1094800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 1095800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 1096800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 1097800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 1098800179c9SKees Cook * 1099800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 1100800179c9SKees Cook */ 1101ad6cc4c3SAl Viro static inline int may_follow_link(struct nameidata *nd, const struct inode *inode) 1102800179c9SKees Cook { 1103e67fe633SChristian Brauner struct mnt_idmap *idmap; 1104a2bd096fSChristian Brauner vfsuid_t vfsuid; 1105ba73d987SChristian Brauner 1106800179c9SKees Cook if (!sysctl_protected_symlinks) 1107800179c9SKees Cook return 0; 1108800179c9SKees Cook 1109e67fe633SChristian Brauner idmap = mnt_idmap(nd->path.mnt); 1110e67fe633SChristian Brauner vfsuid = i_uid_into_vfsuid(idmap, inode); 1111800179c9SKees Cook /* Allowed if owner and follower match. */ 1112a2bd096fSChristian Brauner if (vfsuid_eq_kuid(vfsuid, current_fsuid())) 1113800179c9SKees Cook return 0; 1114800179c9SKees Cook 1115800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 11160f705953SAl Viro if ((nd->dir_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 1117800179c9SKees Cook return 0; 1118800179c9SKees Cook 1119800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 1120a2bd096fSChristian Brauner if (vfsuid_valid(nd->dir_vfsuid) && vfsuid_eq(nd->dir_vfsuid, vfsuid)) 1121800179c9SKees Cook return 0; 1122800179c9SKees Cook 112331956502SAl Viro if (nd->flags & LOOKUP_RCU) 112431956502SAl Viro return -ECHILD; 112531956502SAl Viro 1126ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 1127245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 1128800179c9SKees Cook return -EACCES; 1129800179c9SKees Cook } 1130800179c9SKees Cook 1131800179c9SKees Cook /** 1132800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 11334609e1f1SChristian Brauner * @idmap: idmap of the mount the inode was found from 1134800179c9SKees Cook * @inode: the source inode to hardlink from 1135800179c9SKees Cook * 1136800179c9SKees Cook * Return false if at least one of the following conditions: 1137800179c9SKees Cook * - inode is not a regular file 1138800179c9SKees Cook * - inode is setuid 1139800179c9SKees Cook * - inode is setgid and group-exec 1140800179c9SKees Cook * - access failure for read and write 1141800179c9SKees Cook * 1142800179c9SKees Cook * Otherwise returns true. 1143800179c9SKees Cook */ 11444609e1f1SChristian Brauner static bool safe_hardlink_source(struct mnt_idmap *idmap, 1145ba73d987SChristian Brauner struct inode *inode) 1146800179c9SKees Cook { 1147800179c9SKees Cook umode_t mode = inode->i_mode; 1148800179c9SKees Cook 1149800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1150800179c9SKees Cook if (!S_ISREG(mode)) 1151800179c9SKees Cook return false; 1152800179c9SKees Cook 1153800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1154800179c9SKees Cook if (mode & S_ISUID) 1155800179c9SKees Cook return false; 1156800179c9SKees Cook 1157800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1158800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1159800179c9SKees Cook return false; 1160800179c9SKees Cook 1161800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 11624609e1f1SChristian Brauner if (inode_permission(idmap, inode, MAY_READ | MAY_WRITE)) 1163800179c9SKees Cook return false; 1164800179c9SKees Cook 1165800179c9SKees Cook return true; 1166800179c9SKees Cook } 1167800179c9SKees Cook 1168800179c9SKees Cook /** 1169800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 11704609e1f1SChristian Brauner * @idmap: idmap of the mount the inode was found from 1171800179c9SKees Cook * @link: the source to hardlink from 1172800179c9SKees Cook * 1173800179c9SKees Cook * Block hardlink when all of: 1174800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1175800179c9SKees Cook * - fsuid does not match inode 1176800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1177f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1178800179c9SKees Cook * 11794609e1f1SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 11804609e1f1SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 11814609e1f1SChristian Brauner * care to map the inode according to @idmap before checking permissions. 1182ba73d987SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 11834609e1f1SChristian Brauner * raw inode simply pass @nop_mnt_idmap. 1184ba73d987SChristian Brauner * 1185800179c9SKees Cook * Returns 0 if successful, -ve on error. 1186800179c9SKees Cook */ 11874609e1f1SChristian Brauner int may_linkat(struct mnt_idmap *idmap, const struct path *link) 1188800179c9SKees Cook { 1189593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1190593d1ce8SEric W. Biederman 1191593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1192e67fe633SChristian Brauner if (!vfsuid_valid(i_uid_into_vfsuid(idmap, inode)) || 1193e67fe633SChristian Brauner !vfsgid_valid(i_gid_into_vfsgid(idmap, inode))) 1194593d1ce8SEric W. Biederman return -EOVERFLOW; 1195800179c9SKees Cook 1196800179c9SKees Cook if (!sysctl_protected_hardlinks) 1197800179c9SKees Cook return 0; 1198800179c9SKees Cook 1199800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1200800179c9SKees Cook * otherwise, it must be a safe source. 1201800179c9SKees Cook */ 12024609e1f1SChristian Brauner if (safe_hardlink_source(idmap, inode) || 120301beba79SChristian Brauner inode_owner_or_capable(idmap, inode)) 1204800179c9SKees Cook return 0; 1205800179c9SKees Cook 1206245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1207800179c9SKees Cook return -EPERM; 1208800179c9SKees Cook } 1209800179c9SKees Cook 121030aba665SSalvatore Mesoraca /** 121130aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 121230aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 121330aba665SSalvatore Mesoraca * exist. 1214e67fe633SChristian Brauner * @idmap: idmap of the mount the inode was found from 12152111c3c0SRandy Dunlap * @nd: nameidata pathwalk data 121630aba665SSalvatore Mesoraca * @inode: the inode of the file to open 121730aba665SSalvatore Mesoraca * 121830aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 121930aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 122030aba665SSalvatore Mesoraca * - the file already exists 122130aba665SSalvatore Mesoraca * - we are in a sticky directory 122230aba665SSalvatore Mesoraca * - we don't own the file 122330aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 122430aba665SSalvatore Mesoraca * - the directory is world writable 122530aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 122630aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 122730aba665SSalvatore Mesoraca * be enough. 122830aba665SSalvatore Mesoraca * 1229e67fe633SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 1230e67fe633SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 1231e67fe633SChristian Brauner * care to map the inode according to @idmap before checking permissions. 1232ba73d987SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 1233e67fe633SChristian Brauner * raw inode simply pass @nop_mnt_idmap. 1234ba73d987SChristian Brauner * 123530aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 123630aba665SSalvatore Mesoraca */ 1237e67fe633SChristian Brauner static int may_create_in_sticky(struct mnt_idmap *idmap, 1238ba73d987SChristian Brauner struct nameidata *nd, struct inode *const inode) 123930aba665SSalvatore Mesoraca { 1240ba73d987SChristian Brauner umode_t dir_mode = nd->dir_mode; 1241a2bd096fSChristian Brauner vfsuid_t dir_vfsuid = nd->dir_vfsuid; 1242ba73d987SChristian Brauner 124330aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 124430aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1245d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1246e67fe633SChristian Brauner vfsuid_eq(i_uid_into_vfsuid(idmap, inode), dir_vfsuid) || 1247e67fe633SChristian Brauner vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode), current_fsuid())) 124830aba665SSalvatore Mesoraca return 0; 124930aba665SSalvatore Mesoraca 1250d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1251d0cb5018SAl Viro (dir_mode & 0020 && 125230aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 125330aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1254245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1255245d7369SKees Cook "sticky_create_fifo" : 1256245d7369SKees Cook "sticky_create_regular"; 1257245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 125830aba665SSalvatore Mesoraca return -EACCES; 125930aba665SSalvatore Mesoraca } 126030aba665SSalvatore Mesoraca return 0; 126130aba665SSalvatore Mesoraca } 126230aba665SSalvatore Mesoraca 1263f015f126SDavid Howells /* 1264f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1265f015f126SDavid Howells * 1266f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1267f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1268f015f126SDavid Howells * Up is towards /. 1269f015f126SDavid Howells * 1270f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1271f015f126SDavid Howells * root. 1272f015f126SDavid Howells */ 1273bab77ebfSAl Viro int follow_up(struct path *path) 12741da177e4SLinus Torvalds { 12750714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 12760714a533SAl Viro struct mount *parent; 12771da177e4SLinus Torvalds struct dentry *mountpoint; 127899b7db7bSNick Piggin 127948a066e7SAl Viro read_seqlock_excl(&mount_lock); 12800714a533SAl Viro parent = mnt->mnt_parent; 12813c0a6163SAl Viro if (parent == mnt) { 128248a066e7SAl Viro read_sequnlock_excl(&mount_lock); 12831da177e4SLinus Torvalds return 0; 12841da177e4SLinus Torvalds } 12850714a533SAl Viro mntget(&parent->mnt); 1286a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 128748a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1288bab77ebfSAl Viro dput(path->dentry); 1289bab77ebfSAl Viro path->dentry = mountpoint; 1290bab77ebfSAl Viro mntput(path->mnt); 12910714a533SAl Viro path->mnt = &parent->mnt; 12921da177e4SLinus Torvalds return 1; 12931da177e4SLinus Torvalds } 12944d359507SAl Viro EXPORT_SYMBOL(follow_up); 12951da177e4SLinus Torvalds 12967ef482faSAl Viro static bool choose_mountpoint_rcu(struct mount *m, const struct path *root, 12977ef482faSAl Viro struct path *path, unsigned *seqp) 12987ef482faSAl Viro { 12997ef482faSAl Viro while (mnt_has_parent(m)) { 13007ef482faSAl Viro struct dentry *mountpoint = m->mnt_mountpoint; 13017ef482faSAl Viro 13027ef482faSAl Viro m = m->mnt_parent; 13037ef482faSAl Viro if (unlikely(root->dentry == mountpoint && 13047ef482faSAl Viro root->mnt == &m->mnt)) 13057ef482faSAl Viro break; 13067ef482faSAl Viro if (mountpoint != m->mnt.mnt_root) { 13077ef482faSAl Viro path->mnt = &m->mnt; 13087ef482faSAl Viro path->dentry = mountpoint; 13097ef482faSAl Viro *seqp = read_seqcount_begin(&mountpoint->d_seq); 13107ef482faSAl Viro return true; 13117ef482faSAl Viro } 13127ef482faSAl Viro } 13137ef482faSAl Viro return false; 13147ef482faSAl Viro } 13157ef482faSAl Viro 13162aa38470SAl Viro static bool choose_mountpoint(struct mount *m, const struct path *root, 13172aa38470SAl Viro struct path *path) 13182aa38470SAl Viro { 13192aa38470SAl Viro bool found; 13202aa38470SAl Viro 13212aa38470SAl Viro rcu_read_lock(); 13222aa38470SAl Viro while (1) { 13232aa38470SAl Viro unsigned seq, mseq = read_seqbegin(&mount_lock); 13242aa38470SAl Viro 13252aa38470SAl Viro found = choose_mountpoint_rcu(m, root, path, &seq); 13262aa38470SAl Viro if (unlikely(!found)) { 13272aa38470SAl Viro if (!read_seqretry(&mount_lock, mseq)) 13282aa38470SAl Viro break; 13292aa38470SAl Viro } else { 13302aa38470SAl Viro if (likely(__legitimize_path(path, seq, mseq))) 13312aa38470SAl Viro break; 13322aa38470SAl Viro rcu_read_unlock(); 13332aa38470SAl Viro path_put(path); 13342aa38470SAl Viro rcu_read_lock(); 13352aa38470SAl Viro } 13362aa38470SAl Viro } 13372aa38470SAl Viro rcu_read_unlock(); 13382aa38470SAl Viro return found; 13392aa38470SAl Viro } 13402aa38470SAl Viro 1341b5c84bf6SNick Piggin /* 13429875cf80SDavid Howells * Perform an automount 13439875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 13449875cf80SDavid Howells * were called with. 13451da177e4SLinus Torvalds */ 13461c9f5e06SAl Viro static int follow_automount(struct path *path, int *count, unsigned lookup_flags) 134731e6b01fSNick Piggin { 134825e195aaSAl Viro struct dentry *dentry = path->dentry; 13499875cf80SDavid Howells 13500ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 13510ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 13520ec26fd0SMiklos Szeredi * the name. 13530ec26fd0SMiklos Szeredi * 13540ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 13555a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 13560ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 13570ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 13580ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 13590ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 13605a30d8a2SDavid Howells */ 13611c9f5e06SAl Viro if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 13625d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 136325e195aaSAl Viro dentry->d_inode) 13649875cf80SDavid Howells return -EISDIR; 13650ec26fd0SMiklos Szeredi 13661c9f5e06SAl Viro if (count && (*count)++ >= MAXSYMLINKS) 13679875cf80SDavid Howells return -ELOOP; 13689875cf80SDavid Howells 136925e195aaSAl Viro return finish_automount(dentry->d_op->d_automount(path), path); 1370ea5b778aSDavid Howells } 13719875cf80SDavid Howells 13729875cf80SDavid Howells /* 13739deed3ebSAl Viro * mount traversal - out-of-line part. One note on ->d_flags accesses - 13749deed3ebSAl Viro * dentries are pinned but not locked here, so negative dentry can go 13759deed3ebSAl Viro * positive right under us. Use of smp_load_acquire() provides a barrier 13769deed3ebSAl Viro * sufficient for ->d_inode and ->d_flags consistency. 13779875cf80SDavid Howells */ 13789deed3ebSAl Viro static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped, 13799deed3ebSAl Viro int *count, unsigned lookup_flags) 13809875cf80SDavid Howells { 13819deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 13829875cf80SDavid Howells bool need_mntput = false; 13838aef1884SAl Viro int ret = 0; 13849875cf80SDavid Howells 13859deed3ebSAl Viro while (flags & DCACHE_MANAGED_DENTRY) { 1386cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1387cc53ce53SDavid Howells * being held. */ 1388d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1389fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1390508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1391cc53ce53SDavid Howells if (ret < 0) 13928aef1884SAl Viro break; 1393cc53ce53SDavid Howells } 1394cc53ce53SDavid Howells 13959deed3ebSAl Viro if (flags & DCACHE_MOUNTED) { // something's mounted on it.. 13969875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 13979deed3ebSAl Viro if (mounted) { // ... in our namespace 13989875cf80SDavid Howells dput(path->dentry); 13999875cf80SDavid Howells if (need_mntput) 1400463ffb2eSAl Viro mntput(path->mnt); 1401463ffb2eSAl Viro path->mnt = mounted; 1402463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 14039deed3ebSAl Viro // here we know it's positive 14049deed3ebSAl Viro flags = path->dentry->d_flags; 14059875cf80SDavid Howells need_mntput = true; 14069875cf80SDavid Howells continue; 1407463ffb2eSAl Viro } 14081da177e4SLinus Torvalds } 14099875cf80SDavid Howells 14109deed3ebSAl Viro if (!(flags & DCACHE_NEED_AUTOMOUNT)) 14119deed3ebSAl Viro break; 14129deed3ebSAl Viro 14139deed3ebSAl Viro // uncovered automount point 14149deed3ebSAl Viro ret = follow_automount(path, count, lookup_flags); 14159deed3ebSAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 14169875cf80SDavid Howells if (ret < 0) 14178aef1884SAl Viro break; 14189875cf80SDavid Howells } 14199875cf80SDavid Howells 14209deed3ebSAl Viro if (ret == -EISDIR) 14219deed3ebSAl Viro ret = 0; 14229deed3ebSAl Viro // possible if you race with several mount --move 14239deed3ebSAl Viro if (need_mntput && path->mnt == mnt) 14248aef1884SAl Viro mntput(path->mnt); 14259deed3ebSAl Viro if (!ret && unlikely(d_flags_negative(flags))) 1426d41efb52SAl Viro ret = -ENOENT; 14279deed3ebSAl Viro *jumped = need_mntput; 14288402752eSAl Viro return ret; 14291da177e4SLinus Torvalds } 14301da177e4SLinus Torvalds 14319deed3ebSAl Viro static inline int traverse_mounts(struct path *path, bool *jumped, 14329deed3ebSAl Viro int *count, unsigned lookup_flags) 14339deed3ebSAl Viro { 14349deed3ebSAl Viro unsigned flags = smp_load_acquire(&path->dentry->d_flags); 14359deed3ebSAl Viro 14369deed3ebSAl Viro /* fastpath */ 14379deed3ebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) { 14389deed3ebSAl Viro *jumped = false; 14399deed3ebSAl Viro if (unlikely(d_flags_negative(flags))) 14409deed3ebSAl Viro return -ENOENT; 14419deed3ebSAl Viro return 0; 14429deed3ebSAl Viro } 14439deed3ebSAl Viro return __traverse_mounts(path, flags, jumped, count, lookup_flags); 14449deed3ebSAl Viro } 14459deed3ebSAl Viro 1446cc53ce53SDavid Howells int follow_down_one(struct path *path) 14471da177e4SLinus Torvalds { 14481da177e4SLinus Torvalds struct vfsmount *mounted; 14491da177e4SLinus Torvalds 14501c755af4SAl Viro mounted = lookup_mnt(path); 14511da177e4SLinus Torvalds if (mounted) { 14529393bd07SAl Viro dput(path->dentry); 14539393bd07SAl Viro mntput(path->mnt); 14549393bd07SAl Viro path->mnt = mounted; 14559393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 14561da177e4SLinus Torvalds return 1; 14571da177e4SLinus Torvalds } 14581da177e4SLinus Torvalds return 0; 14591da177e4SLinus Torvalds } 14604d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 14611da177e4SLinus Torvalds 14629875cf80SDavid Howells /* 14639deed3ebSAl Viro * Follow down to the covering mount currently visible to userspace. At each 14649deed3ebSAl Viro * point, the filesystem owning that dentry may be queried as to whether the 14659deed3ebSAl Viro * caller is permitted to proceed or not. 14669deed3ebSAl Viro */ 1467e1f19857SRichard Weinberger int follow_down(struct path *path, unsigned int flags) 14689deed3ebSAl Viro { 14699deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 14709deed3ebSAl Viro bool jumped; 1471e1f19857SRichard Weinberger int ret = traverse_mounts(path, &jumped, NULL, flags); 14729deed3ebSAl Viro 14739deed3ebSAl Viro if (path->mnt != mnt) 14749deed3ebSAl Viro mntput(mnt); 14759deed3ebSAl Viro return ret; 14769deed3ebSAl Viro } 14779deed3ebSAl Viro EXPORT_SYMBOL(follow_down); 14789deed3ebSAl Viro 14799deed3ebSAl Viro /* 1480287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1481287548e4SAl Viro * we meet a managed dentry that would need blocking. 14829875cf80SDavid Howells */ 14833bd8bc89SAl Viro static bool __follow_mount_rcu(struct nameidata *nd, struct path *path) 14849875cf80SDavid Howells { 1485ea936aebSAl Viro struct dentry *dentry = path->dentry; 1486ea936aebSAl Viro unsigned int flags = dentry->d_flags; 1487ea936aebSAl Viro 1488ea936aebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) 1489ea936aebSAl Viro return true; 1490ea936aebSAl Viro 1491ea936aebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1492ea936aebSAl Viro return false; 1493ea936aebSAl Viro 149462a7375eSIan Kent for (;;) { 149562a7375eSIan Kent /* 149662a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 149762a7375eSIan Kent * that wants to block transit. 149862a7375eSIan Kent */ 1499ea936aebSAl Viro if (unlikely(flags & DCACHE_MANAGE_TRANSIT)) { 1500ea936aebSAl Viro int res = dentry->d_op->d_manage(path, true); 1501ea936aebSAl Viro if (res) 1502ea936aebSAl Viro return res == -EISDIR; 1503ea936aebSAl Viro flags = dentry->d_flags; 1504b8faf035SNeilBrown } 150562a7375eSIan Kent 1506ea936aebSAl Viro if (flags & DCACHE_MOUNTED) { 1507ea936aebSAl Viro struct mount *mounted = __lookup_mnt(path->mnt, dentry); 1508ea936aebSAl Viro if (mounted) { 1509c7105365SAl Viro path->mnt = &mounted->mnt; 1510ea936aebSAl Viro dentry = path->dentry = mounted->mnt.mnt_root; 1511bcba1e7dSAl Viro nd->state |= ND_JUMPED; 151203fa86e9SAl Viro nd->next_seq = read_seqcount_begin(&dentry->d_seq); 1513ea936aebSAl Viro flags = dentry->d_flags; 151403fa86e9SAl Viro // makes sure that non-RCU pathwalk could reach 151503fa86e9SAl Viro // this state. 151620aac6c6SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 151720aac6c6SAl Viro return false; 1518ea936aebSAl Viro continue; 15199875cf80SDavid Howells } 1520ea936aebSAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1521ea936aebSAl Viro return false; 1522ea936aebSAl Viro } 1523ea936aebSAl Viro return !(flags & DCACHE_NEED_AUTOMOUNT); 1524ea936aebSAl Viro } 1525287548e4SAl Viro } 1526287548e4SAl Viro 1527db3c9adeSAl Viro static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, 15283bd8bc89SAl Viro struct path *path) 1529bd7c4b50SAl Viro { 15309deed3ebSAl Viro bool jumped; 1531db3c9adeSAl Viro int ret; 1532bd7c4b50SAl Viro 1533db3c9adeSAl Viro path->mnt = nd->path.mnt; 1534db3c9adeSAl Viro path->dentry = dentry; 1535c153007bSAl Viro if (nd->flags & LOOKUP_RCU) { 153603fa86e9SAl Viro unsigned int seq = nd->next_seq; 15373bd8bc89SAl Viro if (likely(__follow_mount_rcu(nd, path))) 15389deed3ebSAl Viro return 0; 153903fa86e9SAl Viro // *path and nd->next_seq might've been clobbered 1540c153007bSAl Viro path->mnt = nd->path.mnt; 1541c153007bSAl Viro path->dentry = dentry; 154203fa86e9SAl Viro nd->next_seq = seq; 154303fa86e9SAl Viro if (!try_to_unlazy_next(nd, dentry)) 154403fa86e9SAl Viro return -ECHILD; 1545c153007bSAl Viro } 15469deed3ebSAl Viro ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags); 15479deed3ebSAl Viro if (jumped) { 15489deed3ebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 15499deed3ebSAl Viro ret = -EXDEV; 15509deed3ebSAl Viro else 1551bcba1e7dSAl Viro nd->state |= ND_JUMPED; 15529deed3ebSAl Viro } 15539deed3ebSAl Viro if (unlikely(ret)) { 15549deed3ebSAl Viro dput(path->dentry); 15559deed3ebSAl Viro if (path->mnt != nd->path.mnt) 15569deed3ebSAl Viro mntput(path->mnt); 1557bd7c4b50SAl Viro } 1558bd7c4b50SAl Viro return ret; 1559bd7c4b50SAl Viro } 1560bd7c4b50SAl Viro 15619875cf80SDavid Howells /* 1562f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1563f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1564baa03890SNick Piggin */ 1565e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1566e3c13928SAl Viro struct dentry *dir, 15676c51e513SAl Viro unsigned int flags) 1568baa03890SNick Piggin { 1569a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1570bad61189SMiklos Szeredi if (dentry) { 1571a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1572bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 157374ff0ffcSAl Viro if (!error) 15745542aa2fSEric W. Biederman d_invalidate(dentry); 1575bad61189SMiklos Szeredi dput(dentry); 157674ff0ffcSAl Viro return ERR_PTR(error); 1577bad61189SMiklos Szeredi } 1578bad61189SMiklos Szeredi } 1579baa03890SNick Piggin return dentry; 1580baa03890SNick Piggin } 1581baa03890SNick Piggin 1582baa03890SNick Piggin /* 1583a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1584a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1585a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1586a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1587a03ece5fSAl Viro * at all. 158844396f4bSJosef Bacik */ 158974d7970fSNamjae Jeon struct dentry *lookup_one_qstr_excl(const struct qstr *name, 159074d7970fSNamjae Jeon struct dentry *base, 159174d7970fSNamjae Jeon unsigned int flags) 159244396f4bSJosef Bacik { 1593a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 159444396f4bSJosef Bacik struct dentry *old; 1595a03ece5fSAl Viro struct inode *dir = base->d_inode; 1596a03ece5fSAl Viro 1597a03ece5fSAl Viro if (dentry) 1598a03ece5fSAl Viro return dentry; 159944396f4bSJosef Bacik 160044396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1601a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 160244396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1603a03ece5fSAl Viro 1604a03ece5fSAl Viro dentry = d_alloc(base, name); 1605a03ece5fSAl Viro if (unlikely(!dentry)) 1606a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 160744396f4bSJosef Bacik 160872bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 160944396f4bSJosef Bacik if (unlikely(old)) { 161044396f4bSJosef Bacik dput(dentry); 161144396f4bSJosef Bacik dentry = old; 161244396f4bSJosef Bacik } 161344396f4bSJosef Bacik return dentry; 161444396f4bSJosef Bacik } 161574d7970fSNamjae Jeon EXPORT_SYMBOL(lookup_one_qstr_excl); 161644396f4bSJosef Bacik 16174cb64024SAl Viro static struct dentry *lookup_fast(struct nameidata *nd) 16181da177e4SLinus Torvalds { 161931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 16205a18fff2SAl Viro int status = 1; 16219875cf80SDavid Howells 16223cac260aSAl Viro /* 1623b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 16245d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 16255d0f49c1SAl Viro * going to fall back to non-racy lookup. 1626b04f784eSNick Piggin */ 162731e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 162803fa86e9SAl Viro dentry = __d_lookup_rcu(parent, &nd->last, &nd->next_seq); 16295d0f49c1SAl Viro if (unlikely(!dentry)) { 1630e36cffedSJens Axboe if (!try_to_unlazy(nd)) 163120e34357SAl Viro return ERR_PTR(-ECHILD); 163220e34357SAl Viro return NULL; 16335d0f49c1SAl Viro } 16345a18fff2SAl Viro 163512f8ad4bSLinus Torvalds /* 163612f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 163712f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 163812f8ad4bSLinus Torvalds */ 16394cb64024SAl Viro if (read_seqcount_retry(&parent->d_seq, nd->seq)) 164020e34357SAl Viro return ERR_PTR(-ECHILD); 16415a18fff2SAl Viro 16424ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1643c153007bSAl Viro if (likely(status > 0)) 164420e34357SAl Viro return dentry; 164503fa86e9SAl Viro if (!try_to_unlazy_next(nd, dentry)) 164620e34357SAl Viro return ERR_PTR(-ECHILD); 164726ddb45eSSteven Rostedt (VMware) if (status == -ECHILD) 1648209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1649209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 16505a18fff2SAl Viro } else { 1651e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 165281e6f520SAl Viro if (unlikely(!dentry)) 165320e34357SAl Viro return NULL; 16544ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16555d0f49c1SAl Viro } 16565a18fff2SAl Viro if (unlikely(status <= 0)) { 1657e9742b53SAl Viro if (!status) 16585d0f49c1SAl Viro d_invalidate(dentry); 16595a18fff2SAl Viro dput(dentry); 166020e34357SAl Viro return ERR_PTR(status); 16615a18fff2SAl Viro } 166220e34357SAl Viro return dentry; 1663697f514dSMiklos Szeredi } 1664697f514dSMiklos Szeredi 1665697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 166688d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1667e3c13928SAl Viro struct dentry *dir, 1668e3c13928SAl Viro unsigned int flags) 1669697f514dSMiklos Szeredi { 167088d8331aSAl Viro struct dentry *dentry, *old; 16711936386eSAl Viro struct inode *inode = dir->d_inode; 1672d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16731936386eSAl Viro 16741936386eSAl Viro /* Don't go there if it's already dead */ 167594bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 167688d8331aSAl Viro return ERR_PTR(-ENOENT); 167794bdd655SAl Viro again: 1678d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 167994bdd655SAl Viro if (IS_ERR(dentry)) 168088d8331aSAl Viro return dentry; 168194bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1682949a852eSAl Viro int error = d_revalidate(dentry, flags); 1683949a852eSAl Viro if (unlikely(error <= 0)) { 168494bdd655SAl Viro if (!error) { 1685949a852eSAl Viro d_invalidate(dentry); 1686949a852eSAl Viro dput(dentry); 168794bdd655SAl Viro goto again; 168894bdd655SAl Viro } 168994bdd655SAl Viro dput(dentry); 1690949a852eSAl Viro dentry = ERR_PTR(error); 1691949a852eSAl Viro } 169294bdd655SAl Viro } else { 16931936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 169485c7f810SAl Viro d_lookup_done(dentry); 16951936386eSAl Viro if (unlikely(old)) { 16961936386eSAl Viro dput(dentry); 16971936386eSAl Viro dentry = old; 1698949a852eSAl Viro } 1699949a852eSAl Viro } 1700e3c13928SAl Viro return dentry; 17011da177e4SLinus Torvalds } 17021da177e4SLinus Torvalds 170388d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 170488d8331aSAl Viro struct dentry *dir, 170588d8331aSAl Viro unsigned int flags) 170688d8331aSAl Viro { 170788d8331aSAl Viro struct inode *inode = dir->d_inode; 170888d8331aSAl Viro struct dentry *res; 170988d8331aSAl Viro inode_lock_shared(inode); 171088d8331aSAl Viro res = __lookup_slow(name, dir, flags); 171188d8331aSAl Viro inode_unlock_shared(inode); 171288d8331aSAl Viro return res; 171388d8331aSAl Viro } 171488d8331aSAl Viro 17154609e1f1SChristian Brauner static inline int may_lookup(struct mnt_idmap *idmap, 1716ba73d987SChristian Brauner struct nameidata *nd) 171752094c8aSAl Viro { 171852094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 17194609e1f1SChristian Brauner int err = inode_permission(idmap, nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 1720e36cffedSJens Axboe if (err != -ECHILD || !try_to_unlazy(nd)) 172152094c8aSAl Viro return err; 172252094c8aSAl Viro } 17234609e1f1SChristian Brauner return inode_permission(idmap, nd->inode, MAY_EXEC); 172452094c8aSAl Viro } 172552094c8aSAl Viro 172603fa86e9SAl Viro static int reserve_stack(struct nameidata *nd, struct path *link) 1727d63ff28fSAl Viro { 172849055906SAl Viro if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) 172949055906SAl Viro return -ELOOP; 17304542576bSAl Viro 17314542576bSAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 17324542576bSAl Viro return 0; 17334542576bSAl Viro if (likely(nd->stack != nd->internal)) 17344542576bSAl Viro return 0; 173560ef60c7SAl Viro if (likely(nd_alloc_stack(nd))) 173649055906SAl Viro return 0; 173760ef60c7SAl Viro 173860ef60c7SAl Viro if (nd->flags & LOOKUP_RCU) { 173960ef60c7SAl Viro // we need to grab link before we do unlazy. And we can't skip 174060ef60c7SAl Viro // unlazy even if we fail to grab the link - cleanup needs it 174103fa86e9SAl Viro bool grabbed_link = legitimize_path(nd, link, nd->next_seq); 174260ef60c7SAl Viro 1743e5ca024eSAl Viro if (!try_to_unlazy(nd) || !grabbed_link) 174460ef60c7SAl Viro return -ECHILD; 174560ef60c7SAl Viro 174660ef60c7SAl Viro if (nd_alloc_stack(nd)) 174760ef60c7SAl Viro return 0; 1748bc40aee0SAl Viro } 174960ef60c7SAl Viro return -ENOMEM; 175049055906SAl Viro } 175149055906SAl Viro 175249055906SAl Viro enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 175349055906SAl Viro 175449055906SAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 175503fa86e9SAl Viro struct inode *inode, int flags) 175649055906SAl Viro { 175749055906SAl Viro struct saved *last; 175849055906SAl Viro const char *res; 175903fa86e9SAl Viro int error = reserve_stack(nd, link); 176049055906SAl Viro 176149055906SAl Viro if (unlikely(error)) { 176249055906SAl Viro if (!(nd->flags & LOOKUP_RCU)) 1763cd179f44SAl Viro path_put(link); 176406708adbSAl Viro return ERR_PTR(error); 1765626de996SAl Viro } 1766ab104923SAl Viro last = nd->stack + nd->depth++; 17671cf2665bSAl Viro last->link = *link; 1768fceef393SAl Viro clear_delayed_call(&last->done); 176903fa86e9SAl Viro last->seq = nd->next_seq; 1770ad6cc4c3SAl Viro 1771b1a81972SAl Viro if (flags & WALK_TRAILING) { 1772ad6cc4c3SAl Viro error = may_follow_link(nd, inode); 1773ad6cc4c3SAl Viro if (unlikely(error)) 1774ad6cc4c3SAl Viro return ERR_PTR(error); 1775ad6cc4c3SAl Viro } 1776ad6cc4c3SAl Viro 1777dab741e0SMattias Nissler if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS) || 1778dab741e0SMattias Nissler unlikely(link->mnt->mnt_flags & MNT_NOSYMFOLLOW)) 1779ad6cc4c3SAl Viro return ERR_PTR(-ELOOP); 1780ad6cc4c3SAl Viro 1781ad6cc4c3SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1782ad6cc4c3SAl Viro touch_atime(&last->link); 1783ad6cc4c3SAl Viro cond_resched(); 1784ad6cc4c3SAl Viro } else if (atime_needs_update(&last->link, inode)) { 1785e36cffedSJens Axboe if (!try_to_unlazy(nd)) 1786ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1787ad6cc4c3SAl Viro touch_atime(&last->link); 1788ad6cc4c3SAl Viro } 1789ad6cc4c3SAl Viro 1790ad6cc4c3SAl Viro error = security_inode_follow_link(link->dentry, inode, 1791ad6cc4c3SAl Viro nd->flags & LOOKUP_RCU); 1792ad6cc4c3SAl Viro if (unlikely(error)) 1793ad6cc4c3SAl Viro return ERR_PTR(error); 1794ad6cc4c3SAl Viro 1795ad6cc4c3SAl Viro res = READ_ONCE(inode->i_link); 1796ad6cc4c3SAl Viro if (!res) { 1797ad6cc4c3SAl Viro const char * (*get)(struct dentry *, struct inode *, 1798ad6cc4c3SAl Viro struct delayed_call *); 1799ad6cc4c3SAl Viro get = inode->i_op->get_link; 1800ad6cc4c3SAl Viro if (nd->flags & LOOKUP_RCU) { 1801ad6cc4c3SAl Viro res = get(NULL, inode, &last->done); 1802e36cffedSJens Axboe if (res == ERR_PTR(-ECHILD) && try_to_unlazy(nd)) 1803ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1804ad6cc4c3SAl Viro } else { 1805ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1806ad6cc4c3SAl Viro } 1807ad6cc4c3SAl Viro if (!res) 1808ad6cc4c3SAl Viro goto all_done; 1809ad6cc4c3SAl Viro if (IS_ERR(res)) 1810ad6cc4c3SAl Viro return res; 1811ad6cc4c3SAl Viro } 1812ad6cc4c3SAl Viro if (*res == '/') { 1813ad6cc4c3SAl Viro error = nd_jump_root(nd); 1814ad6cc4c3SAl Viro if (unlikely(error)) 1815ad6cc4c3SAl Viro return ERR_PTR(error); 1816ad6cc4c3SAl Viro while (unlikely(*++res == '/')) 1817ad6cc4c3SAl Viro ; 1818ad6cc4c3SAl Viro } 1819ad6cc4c3SAl Viro if (*res) 1820ad6cc4c3SAl Viro return res; 1821ad6cc4c3SAl Viro all_done: // pure jump 1822ad6cc4c3SAl Viro put_link(nd); 1823ad6cc4c3SAl Viro return NULL; 1824d63ff28fSAl Viro } 1825d63ff28fSAl Viro 18263ddcd056SLinus Torvalds /* 18273ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 18283ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 18293ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 18303ddcd056SLinus Torvalds * for the common case. 183103fa86e9SAl Viro * 183203fa86e9SAl Viro * NOTE: dentry must be what nd->next_seq had been sampled from. 18333ddcd056SLinus Torvalds */ 1834b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1835a4f5b521SAl Viro struct dentry *dentry) 18363ddcd056SLinus Torvalds { 1837cbae4d12SAl Viro struct path path; 1838a4f5b521SAl Viro struct inode *inode; 18393bd8bc89SAl Viro int err = handle_mounts(nd, dentry, &path); 1840cbae4d12SAl Viro 1841cbae4d12SAl Viro if (err < 0) 1842b0417d2cSAl Viro return ERR_PTR(err); 18433bd8bc89SAl Viro inode = path.dentry->d_inode; 1844cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 18458c4efe22SAl Viro ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) || 1846aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 18478f64fb1cSAl Viro /* not a symlink or should not follow */ 18483bd8bc89SAl Viro if (nd->flags & LOOKUP_RCU) { 18493bd8bc89SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, nd->next_seq)) 18503bd8bc89SAl Viro return ERR_PTR(-ECHILD); 18513bd8bc89SAl Viro if (unlikely(!inode)) 18523bd8bc89SAl Viro return ERR_PTR(-ENOENT); 18533bd8bc89SAl Viro } else { 1854c99687a0SAl Viro dput(nd->path.dentry); 1855c99687a0SAl Viro if (nd->path.mnt != path.mnt) 1856c99687a0SAl Viro mntput(nd->path.mnt); 1857c99687a0SAl Viro } 1858c99687a0SAl Viro nd->path = path; 18598f64fb1cSAl Viro nd->inode = inode; 186003fa86e9SAl Viro nd->seq = nd->next_seq; 1861b0417d2cSAl Viro return NULL; 18628f64fb1cSAl Viro } 1863a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 186484f0cd9eSAl Viro /* make sure that d_is_symlink above matches inode */ 186503fa86e9SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, nd->next_seq)) 1866b0417d2cSAl Viro return ERR_PTR(-ECHILD); 186784f0cd9eSAl Viro } else { 186884f0cd9eSAl Viro if (path.mnt == nd->path.mnt) 186984f0cd9eSAl Viro mntget(path.mnt); 1870a7f77542SAl Viro } 187103fa86e9SAl Viro return pick_link(nd, &path, inode, flags); 18723ddcd056SLinus Torvalds } 18733ddcd056SLinus Torvalds 1874b16c001dSAl Viro static struct dentry *follow_dotdot_rcu(struct nameidata *nd) 1875957dd41dSAl Viro { 187612487f30SAl Viro struct dentry *parent, *old; 1877957dd41dSAl Viro 187812487f30SAl Viro if (path_equal(&nd->path, &nd->root)) 187912487f30SAl Viro goto in_root; 188012487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 18817ef482faSAl Viro struct path path; 1882efe772d6SAl Viro unsigned seq; 18837ef482faSAl Viro if (!choose_mountpoint_rcu(real_mount(nd->path.mnt), 18847ef482faSAl Viro &nd->root, &path, &seq)) 188512487f30SAl Viro goto in_root; 1886efe772d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1887efe772d6SAl Viro return ERR_PTR(-ECHILD); 1888efe772d6SAl Viro nd->path = path; 1889efe772d6SAl Viro nd->inode = path.dentry->d_inode; 1890efe772d6SAl Viro nd->seq = seq; 189103fa86e9SAl Viro // makes sure that non-RCU pathwalk could reach this state 189282ef0698SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1893efe772d6SAl Viro return ERR_PTR(-ECHILD); 1894efe772d6SAl Viro /* we know that mountpoint was pinned */ 1895957dd41dSAl Viro } 189612487f30SAl Viro old = nd->path.dentry; 189712487f30SAl Viro parent = old->d_parent; 189803fa86e9SAl Viro nd->next_seq = read_seqcount_begin(&parent->d_seq); 189903fa86e9SAl Viro // makes sure that non-RCU pathwalk could reach this state 190082ef0698SAl Viro if (read_seqcount_retry(&old->d_seq, nd->seq)) 190112487f30SAl Viro return ERR_PTR(-ECHILD); 190212487f30SAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) 190312487f30SAl Viro return ERR_PTR(-ECHILD); 190412487f30SAl Viro return parent; 190512487f30SAl Viro in_root: 190682ef0698SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1907efe772d6SAl Viro return ERR_PTR(-ECHILD); 1908957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 19097521f22bSAl Viro return ERR_PTR(-ECHILD); 191003fa86e9SAl Viro nd->next_seq = nd->seq; 191151c6546cSAl Viro return nd->path.dentry; 1912957dd41dSAl Viro } 1913957dd41dSAl Viro 1914b16c001dSAl Viro static struct dentry *follow_dotdot(struct nameidata *nd) 1915957dd41dSAl Viro { 191612487f30SAl Viro struct dentry *parent; 191712487f30SAl Viro 1918957dd41dSAl Viro if (path_equal(&nd->path, &nd->root)) 191912487f30SAl Viro goto in_root; 192012487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 19212aa38470SAl Viro struct path path; 19222aa38470SAl Viro 19232aa38470SAl Viro if (!choose_mountpoint(real_mount(nd->path.mnt), 19242aa38470SAl Viro &nd->root, &path)) 192512487f30SAl Viro goto in_root; 1926165200d6SAl Viro path_put(&nd->path); 1927165200d6SAl Viro nd->path = path; 19282aa38470SAl Viro nd->inode = path.dentry->d_inode; 1929165200d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1930165200d6SAl Viro return ERR_PTR(-EXDEV); 193112487f30SAl Viro } 1932957dd41dSAl Viro /* rare case of legitimate dget_parent()... */ 193312487f30SAl Viro parent = dget_parent(nd->path.dentry); 1934957dd41dSAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) { 1935957dd41dSAl Viro dput(parent); 19367521f22bSAl Viro return ERR_PTR(-ENOENT); 1937957dd41dSAl Viro } 1938c2df1968SAl Viro return parent; 193912487f30SAl Viro 194012487f30SAl Viro in_root: 1941957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 19427521f22bSAl Viro return ERR_PTR(-EXDEV); 194351c6546cSAl Viro return dget(nd->path.dentry); 1944957dd41dSAl Viro } 1945957dd41dSAl Viro 19467521f22bSAl Viro static const char *handle_dots(struct nameidata *nd, int type) 1947957dd41dSAl Viro { 1948957dd41dSAl Viro if (type == LAST_DOTDOT) { 19497521f22bSAl Viro const char *error = NULL; 1950c2df1968SAl Viro struct dentry *parent; 1951957dd41dSAl Viro 1952957dd41dSAl Viro if (!nd->root.mnt) { 19537521f22bSAl Viro error = ERR_PTR(set_root(nd)); 1954957dd41dSAl Viro if (error) 1955957dd41dSAl Viro return error; 1956957dd41dSAl Viro } 1957957dd41dSAl Viro if (nd->flags & LOOKUP_RCU) 1958b16c001dSAl Viro parent = follow_dotdot_rcu(nd); 1959957dd41dSAl Viro else 1960b16c001dSAl Viro parent = follow_dotdot(nd); 1961c2df1968SAl Viro if (IS_ERR(parent)) 1962c2df1968SAl Viro return ERR_CAST(parent); 1963a4f5b521SAl Viro error = step_into(nd, WALK_NOFOLLOW, parent); 1964c2df1968SAl Viro if (unlikely(error)) 1965957dd41dSAl Viro return error; 1966957dd41dSAl Viro 1967957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1968957dd41dSAl Viro /* 1969957dd41dSAl Viro * If there was a racing rename or mount along our 1970957dd41dSAl Viro * path, then we can't be sure that ".." hasn't jumped 1971957dd41dSAl Viro * above nd->root (and so userspace should retry or use 1972957dd41dSAl Viro * some fallback). 1973957dd41dSAl Viro */ 1974957dd41dSAl Viro smp_rmb(); 197582ef0698SAl Viro if (__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq)) 19767521f22bSAl Viro return ERR_PTR(-EAGAIN); 197782ef0698SAl Viro if (__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq)) 19787521f22bSAl Viro return ERR_PTR(-EAGAIN); 1979957dd41dSAl Viro } 1980957dd41dSAl Viro } 19817521f22bSAl Viro return NULL; 1982957dd41dSAl Viro } 1983957dd41dSAl Viro 198492d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1985ce57dfc1SAl Viro { 1986db3c9adeSAl Viro struct dentry *dentry; 1987ce57dfc1SAl Viro /* 1988ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1989ce57dfc1SAl Viro * to be able to know about the current root directory and 1990ce57dfc1SAl Viro * parent relationships. 1991ce57dfc1SAl Viro */ 19924693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 19931c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 19944693a547SAl Viro put_link(nd); 19957521f22bSAl Viro return handle_dots(nd, nd->last_type); 19964693a547SAl Viro } 19974cb64024SAl Viro dentry = lookup_fast(nd); 199820e34357SAl Viro if (IS_ERR(dentry)) 199992d27016SAl Viro return ERR_CAST(dentry); 200020e34357SAl Viro if (unlikely(!dentry)) { 2001db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 2002db3c9adeSAl Viro if (IS_ERR(dentry)) 200392d27016SAl Viro return ERR_CAST(dentry); 200420e34357SAl Viro } 200556676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 200656676ec3SAl Viro put_link(nd); 2007a4f5b521SAl Viro return step_into(nd, flags, dentry); 2008ce57dfc1SAl Viro } 2009ce57dfc1SAl Viro 20101da177e4SLinus Torvalds /* 2011bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 2012bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 2013bfcfaa77SLinus Torvalds * 2014bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 2015bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 2016bfcfaa77SLinus Torvalds * fast. 2017bfcfaa77SLinus Torvalds * 2018bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 2019bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 2020bfcfaa77SLinus Torvalds * crossing operation. 2021bfcfaa77SLinus Torvalds * 2022bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 2023bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 2024bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 2025bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 2026bfcfaa77SLinus Torvalds */ 2027bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 2028bfcfaa77SLinus Torvalds 2029f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 2030bfcfaa77SLinus Torvalds 2031468a9428SGeorge Spelvin #ifdef HASH_MIX 2032bfcfaa77SLinus Torvalds 2033468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 2034468a9428SGeorge Spelvin 2035468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 20362a18da7aSGeorge Spelvin /* 20372a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 20382a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 20392a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 20402a18da7aSGeorge Spelvin * and no temporaries. 20412a18da7aSGeorge Spelvin * 20422a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 20432a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 20442a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 20452a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 20462a18da7aSGeorge Spelvin * 20472a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 20482a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 20492a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 20502a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 20512a18da7aSGeorge Spelvin * 20522a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 20532a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 20542a18da7aSGeorge Spelvin * toggling any given output bit. 20552a18da7aSGeorge Spelvin * 20562a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 20572a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 20582a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 20592a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 20602a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 20612a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 20622a18da7aSGeorge Spelvin * Perfect: 8192 258048 20632a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 20642a18da7aSGeorge Spelvin */ 20652a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 20662a18da7aSGeorge Spelvin ( x ^= (a), \ 20672a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 20682a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 20692a18da7aSGeorge Spelvin y *= 9 ) 2070bfcfaa77SLinus Torvalds 20710fed3ac8SGeorge Spelvin /* 20722a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 20732a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 20742a18da7aSGeorge Spelvin * work done before the hash value is used. 20750fed3ac8SGeorge Spelvin */ 20762a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 20770fed3ac8SGeorge Spelvin { 20782a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 20792a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 20802a18da7aSGeorge Spelvin return y >> 32; 20810fed3ac8SGeorge Spelvin } 20820fed3ac8SGeorge Spelvin 2083bfcfaa77SLinus Torvalds #else /* 32-bit case */ 2084bfcfaa77SLinus Torvalds 20852a18da7aSGeorge Spelvin /* 20862a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 20872a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 20882a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 20892a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 20902a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 20912a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 20922a18da7aSGeorge Spelvin * Perfect: 2048 31744 20932a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 20942a18da7aSGeorge Spelvin */ 20952a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 20962a18da7aSGeorge Spelvin ( x ^= (a), \ 20972a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 20982a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 20992a18da7aSGeorge Spelvin y *= 9 ) 2100bfcfaa77SLinus Torvalds 21012a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 21020fed3ac8SGeorge Spelvin { 21032a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 21042a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 21050fed3ac8SGeorge Spelvin } 21060fed3ac8SGeorge Spelvin 2107bfcfaa77SLinus Torvalds #endif 2108bfcfaa77SLinus Torvalds 21092a18da7aSGeorge Spelvin /* 21102a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 21112a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 21122a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 21132a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 21142a18da7aSGeorge Spelvin * finds the delimiter after the name. 21152a18da7aSGeorge Spelvin */ 21168387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 2117bfcfaa77SLinus Torvalds { 21188387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 2119bfcfaa77SLinus Torvalds 2120bfcfaa77SLinus Torvalds for (;;) { 2121fcfd2fbfSGeorge Spelvin if (!len) 2122fcfd2fbfSGeorge Spelvin goto done; 2123e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 2124bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 2125bfcfaa77SLinus Torvalds break; 21262a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2127bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 2128bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 2129bfcfaa77SLinus Torvalds } 21302a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 2131bfcfaa77SLinus Torvalds done: 21322a18da7aSGeorge Spelvin return fold_hash(x, y); 2133bfcfaa77SLinus Torvalds } 2134bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 2135bfcfaa77SLinus Torvalds 2136fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 21378387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2138fcfd2fbfSGeorge Spelvin { 21398387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 21408387ff25SLinus Torvalds unsigned long adata, mask, len; 2141fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2142fcfd2fbfSGeorge Spelvin 21438387ff25SLinus Torvalds len = 0; 21448387ff25SLinus Torvalds goto inside; 21458387ff25SLinus Torvalds 2146fcfd2fbfSGeorge Spelvin do { 21472a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2148fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 21498387ff25SLinus Torvalds inside: 2150fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2151fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2152fcfd2fbfSGeorge Spelvin 2153fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2154fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 21552a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2156fcfd2fbfSGeorge Spelvin 21572a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2158fcfd2fbfSGeorge Spelvin } 2159fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2160fcfd2fbfSGeorge Spelvin 2161bfcfaa77SLinus Torvalds /* 2162bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2163d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2164bfcfaa77SLinus Torvalds */ 21658387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2166bfcfaa77SLinus Torvalds { 21678387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 21688387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 216936126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2170bfcfaa77SLinus Torvalds 21718387ff25SLinus Torvalds len = 0; 21728387ff25SLinus Torvalds goto inside; 21738387ff25SLinus Torvalds 2174bfcfaa77SLinus Torvalds do { 21752a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2176bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 21778387ff25SLinus Torvalds inside: 2178e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 217936126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 218036126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2181bfcfaa77SLinus Torvalds 218236126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 218336126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 218436126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 21852a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 218636126f8fSLinus Torvalds 21872a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2188bfcfaa77SLinus Torvalds } 2189bfcfaa77SLinus Torvalds 21902a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2191bfcfaa77SLinus Torvalds 2192fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 21938387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 21940145acc2SLinus Torvalds { 21958387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 21960145acc2SLinus Torvalds while (len--) 2197fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 21980145acc2SLinus Torvalds return end_name_hash(hash); 21990145acc2SLinus Torvalds } 2200ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 22010145acc2SLinus Torvalds 2202fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 22038387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2204fcfd2fbfSGeorge Spelvin { 22058387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2206fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2207fcfd2fbfSGeorge Spelvin 2208fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2209e0ab7af9SGeorge Spelvin while (c) { 2210fcfd2fbfSGeorge Spelvin len++; 2211fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2212fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2213e0ab7af9SGeorge Spelvin } 2214fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2215fcfd2fbfSGeorge Spelvin } 2216f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2217fcfd2fbfSGeorge Spelvin 22183ddcd056SLinus Torvalds /* 2219200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2220200e9ef7SLinus Torvalds * one character. 2221200e9ef7SLinus Torvalds */ 22228387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2223200e9ef7SLinus Torvalds { 22248387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2225200e9ef7SLinus Torvalds unsigned long len = 0, c; 2226200e9ef7SLinus Torvalds 2227200e9ef7SLinus Torvalds c = (unsigned char)*name; 2228200e9ef7SLinus Torvalds do { 2229200e9ef7SLinus Torvalds len++; 2230200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2231200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2232200e9ef7SLinus Torvalds } while (c && c != '/'); 2233d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2234200e9ef7SLinus Torvalds } 2235200e9ef7SLinus Torvalds 2236bfcfaa77SLinus Torvalds #endif 2237bfcfaa77SLinus Torvalds 2238200e9ef7SLinus Torvalds /* 22391da177e4SLinus Torvalds * Name resolution. 2240ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2241ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 22421da177e4SLinus Torvalds * 2243ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2244ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 22451da177e4SLinus Torvalds */ 22466de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 22471da177e4SLinus Torvalds { 2248d8d4611aSAl Viro int depth = 0; // depth <= nd->depth 22491da177e4SLinus Torvalds int err; 22501da177e4SLinus Torvalds 2251b4c03536SAl Viro nd->last_type = LAST_ROOT; 2252c108837eSAl Viro nd->flags |= LOOKUP_PARENT; 22539b5858e9SAl Viro if (IS_ERR(name)) 22549b5858e9SAl Viro return PTR_ERR(name); 22551da177e4SLinus Torvalds while (*name=='/') 22561da177e4SLinus Torvalds name++; 22571a97d899SAl Viro if (!*name) { 22581a97d899SAl Viro nd->dir_mode = 0; // short-circuit the 'hardening' idiocy 22599e18f10aSAl Viro return 0; 22601a97d899SAl Viro } 22611da177e4SLinus Torvalds 22621da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 22631da177e4SLinus Torvalds for(;;) { 22644609e1f1SChristian Brauner struct mnt_idmap *idmap; 226592d27016SAl Viro const char *link; 2266d6bb3e90SLinus Torvalds u64 hash_len; 2267fe479a58SAl Viro int type; 22681da177e4SLinus Torvalds 22694609e1f1SChristian Brauner idmap = mnt_idmap(nd->path.mnt); 22704609e1f1SChristian Brauner err = may_lookup(idmap, nd); 22711da177e4SLinus Torvalds if (err) 22723595e234SAl Viro return err; 22731da177e4SLinus Torvalds 22748387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 22751da177e4SLinus Torvalds 2276fe479a58SAl Viro type = LAST_NORM; 2277d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2278fe479a58SAl Viro case 2: 2279200e9ef7SLinus Torvalds if (name[1] == '.') { 2280fe479a58SAl Viro type = LAST_DOTDOT; 2281bcba1e7dSAl Viro nd->state |= ND_JUMPED; 228216c2cd71SAl Viro } 2283fe479a58SAl Viro break; 2284fe479a58SAl Viro case 1: 2285fe479a58SAl Viro type = LAST_DOT; 2286fe479a58SAl Viro } 22875a202bcdSAl Viro if (likely(type == LAST_NORM)) { 22885a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 2289bcba1e7dSAl Viro nd->state &= ~ND_JUMPED; 22905a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2291a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2292da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 22935a202bcdSAl Viro if (err < 0) 22943595e234SAl Viro return err; 2295d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2296d6bb3e90SLinus Torvalds name = this.name; 22975a202bcdSAl Viro } 22985a202bcdSAl Viro } 2299fe479a58SAl Viro 2300d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2301d6bb3e90SLinus Torvalds nd->last.name = name; 23025f4a6a69SAl Viro nd->last_type = type; 23035f4a6a69SAl Viro 2304d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2305d6bb3e90SLinus Torvalds if (!*name) 2306bdf6cbf1SAl Viro goto OK; 2307200e9ef7SLinus Torvalds /* 2308200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2309200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2310200e9ef7SLinus Torvalds */ 2311200e9ef7SLinus Torvalds do { 2312d6bb3e90SLinus Torvalds name++; 2313d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 23148620c238SAl Viro if (unlikely(!*name)) { 23158620c238SAl Viro OK: 2316d8d4611aSAl Viro /* pathname or trailing symlink, done */ 2317c108837eSAl Viro if (!depth) { 2318e67fe633SChristian Brauner nd->dir_vfsuid = i_uid_into_vfsuid(idmap, nd->inode); 23190f705953SAl Viro nd->dir_mode = nd->inode->i_mode; 2320c108837eSAl Viro nd->flags &= ~LOOKUP_PARENT; 23218620c238SAl Viro return 0; 2322c108837eSAl Viro } 23238620c238SAl Viro /* last component of nested symlink */ 2324d8d4611aSAl Viro name = nd->stack[--depth].name; 23258c4efe22SAl Viro link = walk_component(nd, 0); 23261c4ff1a8SAl Viro } else { 23271c4ff1a8SAl Viro /* not the last component */ 23288c4efe22SAl Viro link = walk_component(nd, WALK_MORE); 23298620c238SAl Viro } 233092d27016SAl Viro if (unlikely(link)) { 233192d27016SAl Viro if (IS_ERR(link)) 233292d27016SAl Viro return PTR_ERR(link); 233392d27016SAl Viro /* a symlink to follow */ 2334d8d4611aSAl Viro nd->stack[depth++].name = name; 233592d27016SAl Viro name = link; 23369e18f10aSAl Viro continue; 233748c8b0c5SAl Viro } 233897242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 233997242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 2340e36cffedSJens Axboe if (!try_to_unlazy(nd)) 234197242f99SAl Viro return -ECHILD; 234297242f99SAl Viro } 23433595e234SAl Viro return -ENOTDIR; 23445f4a6a69SAl Viro } 2345ce57dfc1SAl Viro } 234697242f99SAl Viro } 23471da177e4SLinus Torvalds 2348edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2349c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 235031e6b01fSNick Piggin { 2351740a1678SAleksa Sarai int error; 2352c8a53ee5SAl Viro const char *s = nd->name->name; 235331e6b01fSNick Piggin 23546c6ec2b0SJens Axboe /* LOOKUP_CACHED requires RCU, ask caller to retry */ 23556c6ec2b0SJens Axboe if ((flags & (LOOKUP_RCU | LOOKUP_CACHED)) == LOOKUP_CACHED) 23566c6ec2b0SJens Axboe return ERR_PTR(-EAGAIN); 23576c6ec2b0SJens Axboe 2358c0eb027eSLinus Torvalds if (!*s) 2359c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2360edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2361edc2b1daSAl Viro rcu_read_lock(); 236203fa86e9SAl Viro else 236303fa86e9SAl Viro nd->seq = nd->next_seq = 0; 2364c0eb027eSLinus Torvalds 2365bcba1e7dSAl Viro nd->flags = flags; 2366bcba1e7dSAl Viro nd->state |= ND_JUMPED; 2367ab87f9a5SAleksa Sarai 2368ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2369ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2370ab87f9a5SAleksa Sarai smp_rmb(); 2371ab87f9a5SAleksa Sarai 2372bcba1e7dSAl Viro if (nd->state & ND_ROOT_PRESET) { 2373b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2374b18825a7SDavid Howells struct inode *inode = root->d_inode; 237593893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2376368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 23775b6ca027SAl Viro nd->path = nd->root; 23785b6ca027SAl Viro nd->inode = inode; 23795b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2380ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 23818f47a016SAl Viro nd->root_seq = nd->seq; 23825b6ca027SAl Viro } else { 23835b6ca027SAl Viro path_get(&nd->path); 23845b6ca027SAl Viro } 2385368ee9baSAl Viro return s; 23865b6ca027SAl Viro } 23875b6ca027SAl Viro 238831e6b01fSNick Piggin nd->root.mnt = NULL; 238931e6b01fSNick Piggin 23908db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 23918db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2392740a1678SAleksa Sarai error = nd_jump_root(nd); 2393740a1678SAleksa Sarai if (unlikely(error)) 2394740a1678SAleksa Sarai return ERR_PTR(error); 2395ef55d917SAl Viro return s; 23968db52c7eSAleksa Sarai } 23978db52c7eSAleksa Sarai 23988db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 23998db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2400e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 240131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2402c28cc364SNick Piggin unsigned seq; 240331e6b01fSNick Piggin 2404c28cc364SNick Piggin do { 2405c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 240631e6b01fSNick Piggin nd->path = fs->pwd; 2407ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2408c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2409c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2410e41f7d4eSAl Viro } else { 2411e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2412ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2413e41f7d4eSAl Viro } 241431e6b01fSNick Piggin } else { 2415582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2416c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 241731e6b01fSNick Piggin struct dentry *dentry; 241831e6b01fSNick Piggin 24192903ff01SAl Viro if (!f.file) 2420368ee9baSAl Viro return ERR_PTR(-EBADF); 242131e6b01fSNick Piggin 24222903ff01SAl Viro dentry = f.file->f_path.dentry; 242331e6b01fSNick Piggin 2424edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 24252903ff01SAl Viro fdput(f); 2426368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2427f52e0c11SAl Viro } 24282903ff01SAl Viro 24292903ff01SAl Viro nd->path = f.file->f_path; 2430e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 243134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 243234a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 24335590ff0dSUlrich Drepper } else { 24342903ff01SAl Viro path_get(&nd->path); 243534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 24361da177e4SLinus Torvalds } 243734a26b99SAl Viro fdput(f); 2438e41f7d4eSAl Viro } 24398db52c7eSAleksa Sarai 2440adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2441adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2442adb21d2bSAleksa Sarai nd->root = nd->path; 2443adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2444adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2445adb21d2bSAleksa Sarai } else { 2446adb21d2bSAleksa Sarai path_get(&nd->root); 2447bcba1e7dSAl Viro nd->state |= ND_ROOT_GRABBED; 2448adb21d2bSAleksa Sarai } 2449adb21d2bSAleksa Sarai } 2450adb21d2bSAleksa Sarai return s; 24519b4a9b14SAl Viro } 24529b4a9b14SAl Viro 24531ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 245495fa25d9SAl Viro { 2455bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2456bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2457bd92d7feSAl Viro 2458c108837eSAl Viro return walk_component(nd, WALK_TRAILING); 2459bd92d7feSAl Viro } 2460bd92d7feSAl Viro 24614f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 24624f757f3cSAl Viro { 2463c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2464db3c9adeSAl Viro dget(nd->path.dentry); 246503fa86e9SAl Viro nd->next_seq = nd->seq; 2466a4f5b521SAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, nd->path.dentry)); 24674f757f3cSAl Viro } 24684f757f3cSAl Viro 24699b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2470c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 24719b4a9b14SAl Viro { 2472c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2473bd92d7feSAl Viro int err; 247431e6b01fSNick Piggin 24759b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 24764f757f3cSAl Viro err = handle_lookup_down(nd); 24775f336e72SAl Viro if (unlikely(err < 0)) 24785f336e72SAl Viro s = ERR_PTR(err); 24794f757f3cSAl Viro } 24804f757f3cSAl Viro 24811ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 24821ccac622SAl Viro (s = lookup_last(nd)) != NULL) 24831ccac622SAl Viro ; 24844f0ed93fSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 24854f0ed93fSAl Viro err = handle_lookup_down(nd); 2486bcba1e7dSAl Viro nd->state &= ~ND_JUMPED; // no d_weak_revalidate(), please... 24874f0ed93fSAl Viro } 24889f1fafeeSAl Viro if (!err) 24899f1fafeeSAl Viro err = complete_walk(nd); 2490bd92d7feSAl Viro 2491deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2492deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2493bd23a539SAl Viro err = -ENOTDIR; 2494625b6d10SAl Viro if (!err) { 2495625b6d10SAl Viro *path = nd->path; 2496625b6d10SAl Viro nd->path.mnt = NULL; 2497625b6d10SAl Viro nd->path.dentry = NULL; 2498625b6d10SAl Viro } 2499deb106c6SAl Viro terminate_walk(nd); 2500bd92d7feSAl Viro return err; 250131e6b01fSNick Piggin } 250231e6b01fSNick Piggin 2503794ebceaSStephen Brennan int filename_lookup(int dfd, struct filename *name, unsigned flags, 25049ad1aaa6SAl Viro struct path *path, struct path *root) 2505873f1eedSJeff Layton { 2506894bc8c4SAl Viro int retval; 25079883d185SAl Viro struct nameidata nd; 2508abc9f5beSAl Viro if (IS_ERR(name)) 2509abc9f5beSAl Viro return PTR_ERR(name); 251006422964SAl Viro set_nameidata(&nd, dfd, name, root); 2511c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2512873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2513c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2514873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2515c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2516873f1eedSJeff Layton 2517873f1eedSJeff Layton if (likely(!retval)) 2518161aff1dSAl Viro audit_inode(name, path->dentry, 2519161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 25209883d185SAl Viro restore_nameidata(); 2521020250f3SDmitry Kadashev return retval; 2522020250f3SDmitry Kadashev } 2523020250f3SDmitry Kadashev 25248bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2525c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2526391172c4SAl Viro struct path *parent) 25278bcb77faSAl Viro { 2528c8a53ee5SAl Viro const char *s = path_init(nd, flags); 25299b5858e9SAl Viro int err = link_path_walk(s, nd); 25308bcb77faSAl Viro if (!err) 25318bcb77faSAl Viro err = complete_walk(nd); 2532391172c4SAl Viro if (!err) { 2533391172c4SAl Viro *parent = nd->path; 2534391172c4SAl Viro nd->path.mnt = NULL; 2535391172c4SAl Viro nd->path.dentry = NULL; 2536391172c4SAl Viro } 2537deb106c6SAl Viro terminate_walk(nd); 25388bcb77faSAl Viro return err; 25398bcb77faSAl Viro } 25408bcb77faSAl Viro 25410766ec82SStephen Brennan /* Note: this does not consume "name" */ 254274d7970fSNamjae Jeon static int __filename_parentat(int dfd, struct filename *name, 2543391172c4SAl Viro unsigned int flags, struct path *parent, 254474d7970fSNamjae Jeon struct qstr *last, int *type, 254574d7970fSNamjae Jeon const struct path *root) 25468bcb77faSAl Viro { 25478bcb77faSAl Viro int retval; 25489883d185SAl Viro struct nameidata nd; 25498bcb77faSAl Viro 25505c31b6ceSAl Viro if (IS_ERR(name)) 25510ee50b47SDmitry Kadashev return PTR_ERR(name); 255274d7970fSNamjae Jeon set_nameidata(&nd, dfd, name, root); 2553c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 25548bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2555c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 25568bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2557c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2558391172c4SAl Viro if (likely(!retval)) { 2559391172c4SAl Viro *last = nd.last; 2560391172c4SAl Viro *type = nd.last_type; 2561c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 2562391172c4SAl Viro } 25639883d185SAl Viro restore_nameidata(); 25640ee50b47SDmitry Kadashev return retval; 25650ee50b47SDmitry Kadashev } 25660ee50b47SDmitry Kadashev 256774d7970fSNamjae Jeon static int filename_parentat(int dfd, struct filename *name, 256874d7970fSNamjae Jeon unsigned int flags, struct path *parent, 256974d7970fSNamjae Jeon struct qstr *last, int *type) 257074d7970fSNamjae Jeon { 257174d7970fSNamjae Jeon return __filename_parentat(dfd, name, flags, parent, last, type, NULL); 257274d7970fSNamjae Jeon } 257374d7970fSNamjae Jeon 257479714f72SAl Viro /* does lookup, returns the object with parent locked */ 25750766ec82SStephen Brennan static struct dentry *__kern_path_locked(struct filename *name, struct path *path) 25765590ff0dSUlrich Drepper { 25775c31b6ceSAl Viro struct dentry *d; 2578391172c4SAl Viro struct qstr last; 25790ee50b47SDmitry Kadashev int type, error; 258051689104SPaul Moore 2581c5f563f9SAl Viro error = filename_parentat(AT_FDCWD, name, 0, path, &last, &type); 25820ee50b47SDmitry Kadashev if (error) 25830ee50b47SDmitry Kadashev return ERR_PTR(error); 25845c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2585391172c4SAl Viro path_put(path); 25865c31b6ceSAl Viro return ERR_PTR(-EINVAL); 258779714f72SAl Viro } 25885955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 258974d7970fSNamjae Jeon d = lookup_one_qstr_excl(&last, path->dentry, 0); 259079714f72SAl Viro if (IS_ERR(d)) { 25915955102cSAl Viro inode_unlock(path->dentry->d_inode); 2592391172c4SAl Viro path_put(path); 259379714f72SAl Viro } 259479714f72SAl Viro return d; 25955590ff0dSUlrich Drepper } 25965590ff0dSUlrich Drepper 25970766ec82SStephen Brennan struct dentry *kern_path_locked(const char *name, struct path *path) 25980766ec82SStephen Brennan { 25990766ec82SStephen Brennan struct filename *filename = getname_kernel(name); 26000766ec82SStephen Brennan struct dentry *res = __kern_path_locked(filename, path); 26010766ec82SStephen Brennan 26020766ec82SStephen Brennan putname(filename); 26030766ec82SStephen Brennan return res; 26040766ec82SStephen Brennan } 26050766ec82SStephen Brennan 2606d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2607d1811465SAl Viro { 2608794ebceaSStephen Brennan struct filename *filename = getname_kernel(name); 2609794ebceaSStephen Brennan int ret = filename_lookup(AT_FDCWD, filename, flags, path, NULL); 2610794ebceaSStephen Brennan 2611794ebceaSStephen Brennan putname(filename); 2612794ebceaSStephen Brennan return ret; 2613794ebceaSStephen Brennan 2614d1811465SAl Viro } 26154d359507SAl Viro EXPORT_SYMBOL(kern_path); 2616d1811465SAl Viro 261716f18200SJosef 'Jeff' Sipek /** 261874d7970fSNamjae Jeon * vfs_path_parent_lookup - lookup a parent path relative to a dentry-vfsmount pair 261974d7970fSNamjae Jeon * @filename: filename structure 262074d7970fSNamjae Jeon * @flags: lookup flags 262174d7970fSNamjae Jeon * @parent: pointer to struct path to fill 262274d7970fSNamjae Jeon * @last: last component 262374d7970fSNamjae Jeon * @type: type of the last component 262474d7970fSNamjae Jeon * @root: pointer to struct path of the base directory 262574d7970fSNamjae Jeon */ 262674d7970fSNamjae Jeon int vfs_path_parent_lookup(struct filename *filename, unsigned int flags, 262774d7970fSNamjae Jeon struct path *parent, struct qstr *last, int *type, 262874d7970fSNamjae Jeon const struct path *root) 262974d7970fSNamjae Jeon { 263074d7970fSNamjae Jeon return __filename_parentat(AT_FDCWD, filename, flags, parent, last, 263174d7970fSNamjae Jeon type, root); 263274d7970fSNamjae Jeon } 263374d7970fSNamjae Jeon EXPORT_SYMBOL(vfs_path_parent_lookup); 263474d7970fSNamjae Jeon 263574d7970fSNamjae Jeon /** 263616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 263716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 263816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 263916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 264016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2641e0a01249SAl Viro * @path: pointer to struct path to fill 264216f18200SJosef 'Jeff' Sipek */ 264316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 264416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2645e0a01249SAl Viro struct path *path) 264616f18200SJosef 'Jeff' Sipek { 2647794ebceaSStephen Brennan struct filename *filename; 26489ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 2649794ebceaSStephen Brennan int ret; 2650794ebceaSStephen Brennan 2651794ebceaSStephen Brennan filename = getname_kernel(name); 26529ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2653794ebceaSStephen Brennan ret = filename_lookup(AT_FDCWD, filename, flags, path, &root); 2654794ebceaSStephen Brennan putname(filename); 2655794ebceaSStephen Brennan return ret; 265616f18200SJosef 'Jeff' Sipek } 26574d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 265816f18200SJosef 'Jeff' Sipek 26594609e1f1SChristian Brauner static int lookup_one_common(struct mnt_idmap *idmap, 2660c2fd68b6SChristian Brauner const char *name, struct dentry *base, int len, 2661c2fd68b6SChristian Brauner struct qstr *this) 26623c95f0dcSAl Viro { 26633c95f0dcSAl Viro this->name = name; 26643c95f0dcSAl Viro this->len = len; 26653c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 26663c95f0dcSAl Viro if (!len) 26673c95f0dcSAl Viro return -EACCES; 26683c95f0dcSAl Viro 26693c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 26703c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 26713c95f0dcSAl Viro return -EACCES; 26723c95f0dcSAl Viro } 26733c95f0dcSAl Viro 26743c95f0dcSAl Viro while (len--) { 26753c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 26763c95f0dcSAl Viro if (c == '/' || c == '\0') 26773c95f0dcSAl Viro return -EACCES; 26783c95f0dcSAl Viro } 26793c95f0dcSAl Viro /* 26803c95f0dcSAl Viro * See if the low-level filesystem might want 26813c95f0dcSAl Viro * to use its own hash.. 26823c95f0dcSAl Viro */ 26833c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 26843c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 26853c95f0dcSAl Viro if (err < 0) 26863c95f0dcSAl Viro return err; 26873c95f0dcSAl Viro } 26883c95f0dcSAl Viro 26894609e1f1SChristian Brauner return inode_permission(idmap, base->d_inode, MAY_EXEC); 26903c95f0dcSAl Viro } 26913c95f0dcSAl Viro 2692eead1911SChristoph Hellwig /** 26930da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 26940da0b7fdSDavid Howells * @name: pathname component to lookup 26950da0b7fdSDavid Howells * @base: base directory to lookup from 26960da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 26970da0b7fdSDavid Howells * 26980da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 26990da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 27000da0b7fdSDavid Howells * 27010da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 27020da0b7fdSDavid Howells * not be called by generic code. 27030da0b7fdSDavid Howells * 27040da0b7fdSDavid Howells * The caller must hold base->i_mutex. 27050da0b7fdSDavid Howells */ 27060da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 27070da0b7fdSDavid Howells { 27080da0b7fdSDavid Howells struct qstr this; 27090da0b7fdSDavid Howells int err; 27100da0b7fdSDavid Howells 27110da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 27120da0b7fdSDavid Howells 27134609e1f1SChristian Brauner err = lookup_one_common(&nop_mnt_idmap, name, base, len, &this); 27140da0b7fdSDavid Howells if (err) 27150da0b7fdSDavid Howells return ERR_PTR(err); 27160da0b7fdSDavid Howells 27170da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 27180da0b7fdSDavid Howells } 27190da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 27200da0b7fdSDavid Howells 27210da0b7fdSDavid Howells /** 2722a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2723eead1911SChristoph Hellwig * @name: pathname component to lookup 2724eead1911SChristoph Hellwig * @base: base directory to lookup from 2725eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2726eead1911SChristoph Hellwig * 2727a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 27289e7543e9SAl Viro * not be called by generic code. 2729bbddca8eSNeilBrown * 2730bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2731eead1911SChristoph Hellwig */ 2732057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2733057f6c01SJames Morris { 27348613a209SAl Viro struct dentry *dentry; 2735057f6c01SJames Morris struct qstr this; 2736cda309deSMiklos Szeredi int err; 2737057f6c01SJames Morris 27385955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 27392f9092e1SDavid Woodhouse 27404609e1f1SChristian Brauner err = lookup_one_common(&nop_mnt_idmap, name, base, len, &this); 2741cda309deSMiklos Szeredi if (err) 2742cda309deSMiklos Szeredi return ERR_PTR(err); 2743cda309deSMiklos Szeredi 27448613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 27458613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2746057f6c01SJames Morris } 27474d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2748057f6c01SJames Morris 2749bbddca8eSNeilBrown /** 2750c2fd68b6SChristian Brauner * lookup_one - filesystem helper to lookup single pathname component 27514609e1f1SChristian Brauner * @idmap: idmap of the mount the lookup is performed from 2752c2fd68b6SChristian Brauner * @name: pathname component to lookup 2753c2fd68b6SChristian Brauner * @base: base directory to lookup from 2754c2fd68b6SChristian Brauner * @len: maximum length @len should be interpreted to 2755c2fd68b6SChristian Brauner * 2756c2fd68b6SChristian Brauner * Note that this routine is purely a helper for filesystem usage and should 2757c2fd68b6SChristian Brauner * not be called by generic code. 2758c2fd68b6SChristian Brauner * 2759c2fd68b6SChristian Brauner * The caller must hold base->i_mutex. 2760c2fd68b6SChristian Brauner */ 27614609e1f1SChristian Brauner struct dentry *lookup_one(struct mnt_idmap *idmap, const char *name, 2762c2fd68b6SChristian Brauner struct dentry *base, int len) 2763c2fd68b6SChristian Brauner { 2764c2fd68b6SChristian Brauner struct dentry *dentry; 2765c2fd68b6SChristian Brauner struct qstr this; 2766c2fd68b6SChristian Brauner int err; 2767c2fd68b6SChristian Brauner 2768c2fd68b6SChristian Brauner WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 2769c2fd68b6SChristian Brauner 27704609e1f1SChristian Brauner err = lookup_one_common(idmap, name, base, len, &this); 2771c2fd68b6SChristian Brauner if (err) 2772c2fd68b6SChristian Brauner return ERR_PTR(err); 2773c2fd68b6SChristian Brauner 2774c2fd68b6SChristian Brauner dentry = lookup_dcache(&this, base, 0); 2775c2fd68b6SChristian Brauner return dentry ? dentry : __lookup_slow(&this, base, 0); 2776c2fd68b6SChristian Brauner } 2777c2fd68b6SChristian Brauner EXPORT_SYMBOL(lookup_one); 2778c2fd68b6SChristian Brauner 2779c2fd68b6SChristian Brauner /** 278000675017SChristian Brauner * lookup_one_unlocked - filesystem helper to lookup single pathname component 27814609e1f1SChristian Brauner * @idmap: idmap of the mount the lookup is performed from 278200675017SChristian Brauner * @name: pathname component to lookup 278300675017SChristian Brauner * @base: base directory to lookup from 278400675017SChristian Brauner * @len: maximum length @len should be interpreted to 278500675017SChristian Brauner * 278600675017SChristian Brauner * Note that this routine is purely a helper for filesystem usage and should 278700675017SChristian Brauner * not be called by generic code. 278800675017SChristian Brauner * 278900675017SChristian Brauner * Unlike lookup_one_len, it should be called without the parent 279000675017SChristian Brauner * i_mutex held, and will take the i_mutex itself if necessary. 279100675017SChristian Brauner */ 27924609e1f1SChristian Brauner struct dentry *lookup_one_unlocked(struct mnt_idmap *idmap, 279300675017SChristian Brauner const char *name, struct dentry *base, 279400675017SChristian Brauner int len) 279500675017SChristian Brauner { 279600675017SChristian Brauner struct qstr this; 279700675017SChristian Brauner int err; 279800675017SChristian Brauner struct dentry *ret; 279900675017SChristian Brauner 28004609e1f1SChristian Brauner err = lookup_one_common(idmap, name, base, len, &this); 280100675017SChristian Brauner if (err) 280200675017SChristian Brauner return ERR_PTR(err); 280300675017SChristian Brauner 280400675017SChristian Brauner ret = lookup_dcache(&this, base, 0); 280500675017SChristian Brauner if (!ret) 280600675017SChristian Brauner ret = lookup_slow(&this, base, 0); 280700675017SChristian Brauner return ret; 280800675017SChristian Brauner } 280900675017SChristian Brauner EXPORT_SYMBOL(lookup_one_unlocked); 281000675017SChristian Brauner 281100675017SChristian Brauner /** 281200675017SChristian Brauner * lookup_one_positive_unlocked - filesystem helper to lookup single 281300675017SChristian Brauner * pathname component 28144609e1f1SChristian Brauner * @idmap: idmap of the mount the lookup is performed from 281500675017SChristian Brauner * @name: pathname component to lookup 281600675017SChristian Brauner * @base: base directory to lookup from 281700675017SChristian Brauner * @len: maximum length @len should be interpreted to 281800675017SChristian Brauner * 281900675017SChristian Brauner * This helper will yield ERR_PTR(-ENOENT) on negatives. The helper returns 282000675017SChristian Brauner * known positive or ERR_PTR(). This is what most of the users want. 282100675017SChristian Brauner * 282200675017SChristian Brauner * Note that pinned negative with unlocked parent _can_ become positive at any 282300675017SChristian Brauner * time, so callers of lookup_one_unlocked() need to be very careful; pinned 282400675017SChristian Brauner * positives have >d_inode stable, so this one avoids such problems. 282500675017SChristian Brauner * 282600675017SChristian Brauner * Note that this routine is purely a helper for filesystem usage and should 282700675017SChristian Brauner * not be called by generic code. 282800675017SChristian Brauner * 282900675017SChristian Brauner * The helper should be called without i_mutex held. 283000675017SChristian Brauner */ 28314609e1f1SChristian Brauner struct dentry *lookup_one_positive_unlocked(struct mnt_idmap *idmap, 283200675017SChristian Brauner const char *name, 283300675017SChristian Brauner struct dentry *base, int len) 283400675017SChristian Brauner { 28354609e1f1SChristian Brauner struct dentry *ret = lookup_one_unlocked(idmap, name, base, len); 283600675017SChristian Brauner 283700675017SChristian Brauner if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 283800675017SChristian Brauner dput(ret); 283900675017SChristian Brauner ret = ERR_PTR(-ENOENT); 284000675017SChristian Brauner } 284100675017SChristian Brauner return ret; 284200675017SChristian Brauner } 284300675017SChristian Brauner EXPORT_SYMBOL(lookup_one_positive_unlocked); 284400675017SChristian Brauner 284500675017SChristian Brauner /** 2846bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2847bbddca8eSNeilBrown * @name: pathname component to lookup 2848bbddca8eSNeilBrown * @base: base directory to lookup from 2849bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2850bbddca8eSNeilBrown * 2851bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2852bbddca8eSNeilBrown * not be called by generic code. 2853bbddca8eSNeilBrown * 2854bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2855bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2856bbddca8eSNeilBrown */ 2857bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2858bbddca8eSNeilBrown struct dentry *base, int len) 2859bbddca8eSNeilBrown { 28604609e1f1SChristian Brauner return lookup_one_unlocked(&nop_mnt_idmap, name, base, len); 2861bbddca8eSNeilBrown } 2862bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2863bbddca8eSNeilBrown 28646c2d4798SAl Viro /* 28656c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 28666c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 28676c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 28686c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 28696c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 28706c2d4798SAl Viro * this one avoids such problems. 28716c2d4798SAl Viro */ 28726c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 28736c2d4798SAl Viro struct dentry *base, int len) 28746c2d4798SAl Viro { 28754609e1f1SChristian Brauner return lookup_one_positive_unlocked(&nop_mnt_idmap, name, base, len); 28766c2d4798SAl Viro } 28776c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 28786c2d4798SAl Viro 2879eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2880eedf265aSEric W. Biederman int path_pts(struct path *path) 2881eedf265aSEric W. Biederman { 2882eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2883eedf265aSEric W. Biederman * the input path. 2884eedf265aSEric W. Biederman */ 2885a6a7eb76SAl Viro struct dentry *parent = dget_parent(path->dentry); 2886a6a7eb76SAl Viro struct dentry *child; 288719f6028aSAl Viro struct qstr this = QSTR_INIT("pts", 3); 2888eedf265aSEric W. Biederman 2889a6a7eb76SAl Viro if (unlikely(!path_connected(path->mnt, parent))) { 2890a6a7eb76SAl Viro dput(parent); 289163b27720SAl Viro return -ENOENT; 2892a6a7eb76SAl Viro } 289363b27720SAl Viro dput(path->dentry); 289463b27720SAl Viro path->dentry = parent; 2895eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 28960d5a4f8fSWang Ming if (IS_ERR_OR_NULL(child)) 2897eedf265aSEric W. Biederman return -ENOENT; 2898eedf265aSEric W. Biederman 2899eedf265aSEric W. Biederman path->dentry = child; 2900eedf265aSEric W. Biederman dput(parent); 2901e1f19857SRichard Weinberger follow_down(path, 0); 2902eedf265aSEric W. Biederman return 0; 2903eedf265aSEric W. Biederman } 2904eedf265aSEric W. Biederman #endif 2905eedf265aSEric W. Biederman 29061fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 29071fa1e7f6SAndy Whitcroft struct path *path, int *empty) 29081da177e4SLinus Torvalds { 2909794ebceaSStephen Brennan struct filename *filename = getname_flags(name, flags, empty); 2910794ebceaSStephen Brennan int ret = filename_lookup(dfd, filename, flags, path, NULL); 2911794ebceaSStephen Brennan 2912794ebceaSStephen Brennan putname(filename); 2913794ebceaSStephen Brennan return ret; 29141da177e4SLinus Torvalds } 2915b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 29161fa1e7f6SAndy Whitcroft 29179452e93eSChristian Brauner int __check_sticky(struct mnt_idmap *idmap, struct inode *dir, 2918ba73d987SChristian Brauner struct inode *inode) 29191da177e4SLinus Torvalds { 29208e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2921da9592edSDavid Howells 2922e67fe633SChristian Brauner if (vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode), fsuid)) 29231da177e4SLinus Torvalds return 0; 2924e67fe633SChristian Brauner if (vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, dir), fsuid)) 29251da177e4SLinus Torvalds return 0; 29269452e93eSChristian Brauner return !capable_wrt_inode_uidgid(idmap, inode, CAP_FOWNER); 29271da177e4SLinus Torvalds } 2928cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 29291da177e4SLinus Torvalds 29301da177e4SLinus Torvalds /* 29311da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 29321da177e4SLinus Torvalds * whether the type of victim is right. 29331da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 29341da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 29351da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 29361da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 29371da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 29381da177e4SLinus Torvalds * a. be owner of dir, or 29391da177e4SLinus Torvalds * b. be owner of victim, or 29401da177e4SLinus Torvalds * c. have CAP_FOWNER capability 29411da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 29421da177e4SLinus Torvalds * links pointing to it. 29430bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 29440bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 29450bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 29460bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 29470bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 29481da177e4SLinus Torvalds * nfs_async_unlink(). 29491da177e4SLinus Torvalds */ 29504609e1f1SChristian Brauner static int may_delete(struct mnt_idmap *idmap, struct inode *dir, 2951ba73d987SChristian Brauner struct dentry *victim, bool isdir) 29521da177e4SLinus Torvalds { 295363afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 29541da177e4SLinus Torvalds int error; 29551da177e4SLinus Torvalds 2956b18825a7SDavid Howells if (d_is_negative(victim)) 29571da177e4SLinus Torvalds return -ENOENT; 2958b18825a7SDavid Howells BUG_ON(!inode); 29591da177e4SLinus Torvalds 29601da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2961593d1ce8SEric W. Biederman 2962593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2963e67fe633SChristian Brauner if (!vfsuid_valid(i_uid_into_vfsuid(idmap, inode)) || 2964e67fe633SChristian Brauner !vfsgid_valid(i_gid_into_vfsgid(idmap, inode))) 2965593d1ce8SEric W. Biederman return -EOVERFLOW; 2966593d1ce8SEric W. Biederman 29674fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 29681da177e4SLinus Torvalds 29694609e1f1SChristian Brauner error = inode_permission(idmap, dir, MAY_WRITE | MAY_EXEC); 29701da177e4SLinus Torvalds if (error) 29711da177e4SLinus Torvalds return error; 29721da177e4SLinus Torvalds if (IS_APPEND(dir)) 29731da177e4SLinus Torvalds return -EPERM; 2974b18825a7SDavid Howells 29759452e93eSChristian Brauner if (check_sticky(idmap, dir, inode) || IS_APPEND(inode) || 2976ba73d987SChristian Brauner IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || 29774609e1f1SChristian Brauner HAS_UNMAPPED_ID(idmap, inode)) 29781da177e4SLinus Torvalds return -EPERM; 29791da177e4SLinus Torvalds if (isdir) { 298044b1d530SMiklos Szeredi if (!d_is_dir(victim)) 29811da177e4SLinus Torvalds return -ENOTDIR; 29821da177e4SLinus Torvalds if (IS_ROOT(victim)) 29831da177e4SLinus Torvalds return -EBUSY; 298444b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 29851da177e4SLinus Torvalds return -EISDIR; 29861da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 29871da177e4SLinus Torvalds return -ENOENT; 29881da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 29891da177e4SLinus Torvalds return -EBUSY; 29901da177e4SLinus Torvalds return 0; 29911da177e4SLinus Torvalds } 29921da177e4SLinus Torvalds 29931da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 29941da177e4SLinus Torvalds * dir. 29951da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 29961da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 29971da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2998036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2999036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 3000036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 30011da177e4SLinus Torvalds */ 30024609e1f1SChristian Brauner static inline int may_create(struct mnt_idmap *idmap, 3003ba73d987SChristian Brauner struct inode *dir, struct dentry *child) 30041da177e4SLinus Torvalds { 300514e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 30061da177e4SLinus Torvalds if (child->d_inode) 30071da177e4SLinus Torvalds return -EEXIST; 30081da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 30091da177e4SLinus Torvalds return -ENOENT; 30104609e1f1SChristian Brauner if (!fsuidgid_has_mapping(dir->i_sb, idmap)) 3011036d5236SEric W. Biederman return -EOVERFLOW; 30128e538913SChristian Brauner 30134609e1f1SChristian Brauner return inode_permission(idmap, dir, MAY_WRITE | MAY_EXEC); 30141da177e4SLinus Torvalds } 30151da177e4SLinus Torvalds 30169bc37e04SAl Viro static struct dentry *lock_two_directories(struct dentry *p1, struct dentry *p2) 30171da177e4SLinus Torvalds { 30181da177e4SLinus Torvalds struct dentry *p; 30191da177e4SLinus Torvalds 3020e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 3021e2761a11SOGAWA Hirofumi if (p) { 30225955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 30235955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 30241da177e4SLinus Torvalds return p; 30251da177e4SLinus Torvalds } 30261da177e4SLinus Torvalds 3027e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 3028e2761a11SOGAWA Hirofumi if (p) { 30295955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 30305955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 30311da177e4SLinus Torvalds return p; 30321da177e4SLinus Torvalds } 30331da177e4SLinus Torvalds 3034f23ce757SJan Kara lock_two_inodes(p1->d_inode, p2->d_inode, 3035f23ce757SJan Kara I_MUTEX_PARENT, I_MUTEX_PARENT2); 30361da177e4SLinus Torvalds return NULL; 30371da177e4SLinus Torvalds } 30389bc37e04SAl Viro 30399bc37e04SAl Viro /* 30409bc37e04SAl Viro * p1 and p2 should be directories on the same fs. 30419bc37e04SAl Viro */ 30429bc37e04SAl Viro struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 30439bc37e04SAl Viro { 30449bc37e04SAl Viro if (p1 == p2) { 30459bc37e04SAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 30469bc37e04SAl Viro return NULL; 30479bc37e04SAl Viro } 30489bc37e04SAl Viro 30499bc37e04SAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 30509bc37e04SAl Viro return lock_two_directories(p1, p2); 30519bc37e04SAl Viro } 30524d359507SAl Viro EXPORT_SYMBOL(lock_rename); 30531da177e4SLinus Torvalds 30549bc37e04SAl Viro /* 30559bc37e04SAl Viro * c1 and p2 should be on the same fs. 30569bc37e04SAl Viro */ 30579bc37e04SAl Viro struct dentry *lock_rename_child(struct dentry *c1, struct dentry *p2) 30589bc37e04SAl Viro { 30599bc37e04SAl Viro if (READ_ONCE(c1->d_parent) == p2) { 30609bc37e04SAl Viro /* 30619bc37e04SAl Viro * hopefully won't need to touch ->s_vfs_rename_mutex at all. 30629bc37e04SAl Viro */ 30639bc37e04SAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 30649bc37e04SAl Viro /* 30659bc37e04SAl Viro * now that p2 is locked, nobody can move in or out of it, 30669bc37e04SAl Viro * so the test below is safe. 30679bc37e04SAl Viro */ 30689bc37e04SAl Viro if (likely(c1->d_parent == p2)) 30699bc37e04SAl Viro return NULL; 30709bc37e04SAl Viro 30719bc37e04SAl Viro /* 30729bc37e04SAl Viro * c1 got moved out of p2 while we'd been taking locks; 30739bc37e04SAl Viro * unlock and fall back to slow case. 30749bc37e04SAl Viro */ 30759bc37e04SAl Viro inode_unlock(p2->d_inode); 30769bc37e04SAl Viro } 30779bc37e04SAl Viro 30789bc37e04SAl Viro mutex_lock(&c1->d_sb->s_vfs_rename_mutex); 30799bc37e04SAl Viro /* 30809bc37e04SAl Viro * nobody can move out of any directories on this fs. 30819bc37e04SAl Viro */ 30829bc37e04SAl Viro if (likely(c1->d_parent != p2)) 30839bc37e04SAl Viro return lock_two_directories(c1->d_parent, p2); 30849bc37e04SAl Viro 30859bc37e04SAl Viro /* 30869bc37e04SAl Viro * c1 got moved into p2 while we were taking locks; 30879bc37e04SAl Viro * we need p2 locked and ->s_vfs_rename_mutex unlocked, 30889bc37e04SAl Viro * for consistency with lock_rename(). 30899bc37e04SAl Viro */ 30909bc37e04SAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 30919bc37e04SAl Viro mutex_unlock(&c1->d_sb->s_vfs_rename_mutex); 30929bc37e04SAl Viro return NULL; 30939bc37e04SAl Viro } 30949bc37e04SAl Viro EXPORT_SYMBOL(lock_rename_child); 30959bc37e04SAl Viro 30961da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 30971da177e4SLinus Torvalds { 30985955102cSAl Viro inode_unlock(p1->d_inode); 30991da177e4SLinus Torvalds if (p1 != p2) { 31005955102cSAl Viro inode_unlock(p2->d_inode); 3101fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 31021da177e4SLinus Torvalds } 31031da177e4SLinus Torvalds } 31044d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 31051da177e4SLinus Torvalds 31066521f891SChristian Brauner /** 31071639a49cSYang Xu * mode_strip_umask - handle vfs umask stripping 31081639a49cSYang Xu * @dir: parent directory of the new inode 31091639a49cSYang Xu * @mode: mode of the new inode to be created in @dir 31101639a49cSYang Xu * 31111639a49cSYang Xu * Umask stripping depends on whether or not the filesystem supports POSIX 31121639a49cSYang Xu * ACLs. If the filesystem doesn't support it umask stripping is done directly 31131639a49cSYang Xu * in here. If the filesystem does support POSIX ACLs umask stripping is 31141639a49cSYang Xu * deferred until the filesystem calls posix_acl_create(). 31151639a49cSYang Xu * 31161639a49cSYang Xu * Returns: mode 31171639a49cSYang Xu */ 31181639a49cSYang Xu static inline umode_t mode_strip_umask(const struct inode *dir, umode_t mode) 31191639a49cSYang Xu { 31201639a49cSYang Xu if (!IS_POSIXACL(dir)) 31211639a49cSYang Xu mode &= ~current_umask(); 31221639a49cSYang Xu return mode; 31231639a49cSYang Xu } 31241639a49cSYang Xu 31251639a49cSYang Xu /** 31261639a49cSYang Xu * vfs_prepare_mode - prepare the mode to be used for a new inode 31279452e93eSChristian Brauner * @idmap: idmap of the mount the inode was found from 31281639a49cSYang Xu * @dir: parent directory of the new inode 31291639a49cSYang Xu * @mode: mode of the new inode 31301639a49cSYang Xu * @mask_perms: allowed permission by the vfs 31311639a49cSYang Xu * @type: type of file to be created 31321639a49cSYang Xu * 31331639a49cSYang Xu * This helper consolidates and enforces vfs restrictions on the @mode of a new 31341639a49cSYang Xu * object to be created. 31351639a49cSYang Xu * 31361639a49cSYang Xu * Umask stripping depends on whether the filesystem supports POSIX ACLs (see 31371639a49cSYang Xu * the kernel documentation for mode_strip_umask()). Moving umask stripping 31381639a49cSYang Xu * after setgid stripping allows the same ordering for both non-POSIX ACL and 31391639a49cSYang Xu * POSIX ACL supporting filesystems. 31401639a49cSYang Xu * 31411639a49cSYang Xu * Note that it's currently valid for @type to be 0 if a directory is created. 31421639a49cSYang Xu * Filesystems raise that flag individually and we need to check whether each 31431639a49cSYang Xu * filesystem can deal with receiving S_IFDIR from the vfs before we enforce a 31441639a49cSYang Xu * non-zero type. 31451639a49cSYang Xu * 31461639a49cSYang Xu * Returns: mode to be passed to the filesystem 31471639a49cSYang Xu */ 31489452e93eSChristian Brauner static inline umode_t vfs_prepare_mode(struct mnt_idmap *idmap, 31491639a49cSYang Xu const struct inode *dir, umode_t mode, 31501639a49cSYang Xu umode_t mask_perms, umode_t type) 31511639a49cSYang Xu { 31529452e93eSChristian Brauner mode = mode_strip_sgid(idmap, dir, mode); 31531639a49cSYang Xu mode = mode_strip_umask(dir, mode); 31541639a49cSYang Xu 31551639a49cSYang Xu /* 31561639a49cSYang Xu * Apply the vfs mandated allowed permission mask and set the type of 31571639a49cSYang Xu * file to be created before we call into the filesystem. 31581639a49cSYang Xu */ 31591639a49cSYang Xu mode &= (mask_perms & ~S_IFMT); 31601639a49cSYang Xu mode |= (type & S_IFMT); 31611639a49cSYang Xu 31621639a49cSYang Xu return mode; 31631639a49cSYang Xu } 31641639a49cSYang Xu 31651639a49cSYang Xu /** 31666521f891SChristian Brauner * vfs_create - create new file 3167abf08576SChristian Brauner * @idmap: idmap of the mount the inode was found from 31686521f891SChristian Brauner * @dir: inode of @dentry 31696521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 31706521f891SChristian Brauner * @mode: mode of the new file 31716521f891SChristian Brauner * @want_excl: whether the file must not yet exist 31726521f891SChristian Brauner * 31736521f891SChristian Brauner * Create a new file. 31746521f891SChristian Brauner * 3175abf08576SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 3176abf08576SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 3177abf08576SChristian Brauner * care to map the inode according to @idmap before checking permissions. 31786521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 3179abf08576SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 31806521f891SChristian Brauner */ 3181abf08576SChristian Brauner int vfs_create(struct mnt_idmap *idmap, struct inode *dir, 31826521f891SChristian Brauner struct dentry *dentry, umode_t mode, bool want_excl) 31831da177e4SLinus Torvalds { 3184abf08576SChristian Brauner int error; 3185abf08576SChristian Brauner 31864609e1f1SChristian Brauner error = may_create(idmap, dir, dentry); 31871da177e4SLinus Torvalds if (error) 31881da177e4SLinus Torvalds return error; 31891da177e4SLinus Torvalds 3190acfa4380SAl Viro if (!dir->i_op->create) 31911da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 31921639a49cSYang Xu 31939452e93eSChristian Brauner mode = vfs_prepare_mode(idmap, dir, mode, S_IALLUGO, S_IFREG); 31941da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 31951da177e4SLinus Torvalds if (error) 31961da177e4SLinus Torvalds return error; 31976c960e68SChristian Brauner error = dir->i_op->create(idmap, dir, dentry, mode, want_excl); 3198a74574aaSStephen Smalley if (!error) 3199f38aa942SAmy Griffis fsnotify_create(dir, dentry); 32001da177e4SLinus Torvalds return error; 32011da177e4SLinus Torvalds } 32024d359507SAl Viro EXPORT_SYMBOL(vfs_create); 32031da177e4SLinus Torvalds 32048e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 32058e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 32068e6c848eSAl Viro void *arg) 32078e6c848eSAl Viro { 32088e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 32094609e1f1SChristian Brauner int error = may_create(&nop_mnt_idmap, dir, dentry); 32108e6c848eSAl Viro if (error) 32118e6c848eSAl Viro return error; 32128e6c848eSAl Viro 32138e6c848eSAl Viro mode &= S_IALLUGO; 32148e6c848eSAl Viro mode |= S_IFREG; 32158e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 32168e6c848eSAl Viro if (error) 32178e6c848eSAl Viro return error; 32188e6c848eSAl Viro error = f(dentry, mode, arg); 32198e6c848eSAl Viro if (!error) 32208e6c848eSAl Viro fsnotify_create(dir, dentry); 32218e6c848eSAl Viro return error; 32228e6c848eSAl Viro } 32238e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 32248e6c848eSAl Viro 3225a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 3226a2982cc9SEric W. Biederman { 3227a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 3228a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 3229a2982cc9SEric W. Biederman } 3230a2982cc9SEric W. Biederman 32314609e1f1SChristian Brauner static int may_open(struct mnt_idmap *idmap, const struct path *path, 3232ba73d987SChristian Brauner int acc_mode, int flag) 32331da177e4SLinus Torvalds { 32343fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 32351da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 32361da177e4SLinus Torvalds int error; 32371da177e4SLinus Torvalds 32381da177e4SLinus Torvalds if (!inode) 32391da177e4SLinus Torvalds return -ENOENT; 32401da177e4SLinus Torvalds 3241c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 3242c8fe8f30SChristoph Hellwig case S_IFLNK: 32431da177e4SLinus Torvalds return -ELOOP; 3244c8fe8f30SChristoph Hellwig case S_IFDIR: 3245fc4177beSKees Cook if (acc_mode & MAY_WRITE) 32461da177e4SLinus Torvalds return -EISDIR; 3247fc4177beSKees Cook if (acc_mode & MAY_EXEC) 3248fc4177beSKees Cook return -EACCES; 3249c8fe8f30SChristoph Hellwig break; 3250c8fe8f30SChristoph Hellwig case S_IFBLK: 3251c8fe8f30SChristoph Hellwig case S_IFCHR: 3252a2982cc9SEric W. Biederman if (!may_open_dev(path)) 32531da177e4SLinus Torvalds return -EACCES; 3254633fb6acSKees Cook fallthrough; 3255c8fe8f30SChristoph Hellwig case S_IFIFO: 3256c8fe8f30SChristoph Hellwig case S_IFSOCK: 3257633fb6acSKees Cook if (acc_mode & MAY_EXEC) 3258633fb6acSKees Cook return -EACCES; 32591da177e4SLinus Torvalds flag &= ~O_TRUNC; 3260c8fe8f30SChristoph Hellwig break; 32610fd338b2SKees Cook case S_IFREG: 32620fd338b2SKees Cook if ((acc_mode & MAY_EXEC) && path_noexec(path)) 32630fd338b2SKees Cook return -EACCES; 32640fd338b2SKees Cook break; 32654a3fd211SDave Hansen } 3266b41572e9SDave Hansen 32674609e1f1SChristian Brauner error = inode_permission(idmap, inode, MAY_OPEN | acc_mode); 3268b41572e9SDave Hansen if (error) 3269b41572e9SDave Hansen return error; 32706146f0d5SMimi Zohar 32711da177e4SLinus Torvalds /* 32721da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 32731da177e4SLinus Torvalds */ 32741da177e4SLinus Torvalds if (IS_APPEND(inode)) { 32758737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 32767715b521SAl Viro return -EPERM; 32771da177e4SLinus Torvalds if (flag & O_TRUNC) 32787715b521SAl Viro return -EPERM; 32791da177e4SLinus Torvalds } 32801da177e4SLinus Torvalds 32811da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 328201beba79SChristian Brauner if (flag & O_NOATIME && !inode_owner_or_capable(idmap, inode)) 32837715b521SAl Viro return -EPERM; 32841da177e4SLinus Torvalds 3285f3c7691eSJ. Bruce Fields return 0; 32867715b521SAl Viro } 32877715b521SAl Viro 3288abf08576SChristian Brauner static int handle_truncate(struct mnt_idmap *idmap, struct file *filp) 32897715b521SAl Viro { 3290f0bb5aafSAl Viro const struct path *path = &filp->f_path; 32917715b521SAl Viro struct inode *inode = path->dentry->d_inode; 32927715b521SAl Viro int error = get_write_access(inode); 32931da177e4SLinus Torvalds if (error) 32947715b521SAl Viro return error; 3295482e0007SJeff Layton 32963350607dSGünther Noack error = security_file_truncate(filp); 32971da177e4SLinus Torvalds if (!error) { 3298abf08576SChristian Brauner error = do_truncate(idmap, path->dentry, 0, 3299d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 3300e1181ee6SJeff Layton filp); 33011da177e4SLinus Torvalds } 33021da177e4SLinus Torvalds put_write_access(inode); 3303acd0c935SMimi Zohar return error; 33041da177e4SLinus Torvalds } 33051da177e4SLinus Torvalds 3306d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 3307d57999e1SDave Hansen { 33088a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 33098a5e929dSAl Viro flag--; 3310d57999e1SDave Hansen return flag; 3311d57999e1SDave Hansen } 3312d57999e1SDave Hansen 33134609e1f1SChristian Brauner static int may_o_create(struct mnt_idmap *idmap, 3314ba73d987SChristian Brauner const struct path *dir, struct dentry *dentry, 3315ba73d987SChristian Brauner umode_t mode) 3316d18e9008SMiklos Szeredi { 3317d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 3318d18e9008SMiklos Szeredi if (error) 3319d18e9008SMiklos Szeredi return error; 3320d18e9008SMiklos Szeredi 33214609e1f1SChristian Brauner if (!fsuidgid_has_mapping(dir->dentry->d_sb, idmap)) 33221328c727SSeth Forshee return -EOVERFLOW; 33231328c727SSeth Forshee 33244609e1f1SChristian Brauner error = inode_permission(idmap, dir->dentry->d_inode, 332547291baaSChristian Brauner MAY_WRITE | MAY_EXEC); 3326d18e9008SMiklos Szeredi if (error) 3327d18e9008SMiklos Szeredi return error; 3328d18e9008SMiklos Szeredi 3329d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 3330d18e9008SMiklos Szeredi } 3331d18e9008SMiklos Szeredi 33321acf0af9SDavid Howells /* 33331acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 33341acf0af9SDavid Howells * dentry. 33351acf0af9SDavid Howells * 33361acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 33371acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 33381acf0af9SDavid Howells * 333900a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 334000a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 334100a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 33421acf0af9SDavid Howells * 33431acf0af9SDavid Howells * Returns an error code otherwise. 33441acf0af9SDavid Howells */ 3345239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 3346239eb983SAl Viro struct file *file, 33473ec2eef1SAl Viro int open_flag, umode_t mode) 3348d18e9008SMiklos Szeredi { 3349d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3350d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3351d18e9008SMiklos Szeredi int error; 3352d18e9008SMiklos Szeredi 3353d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3354d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3355d18e9008SMiklos Szeredi 335630d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 335730d90494SAl Viro file->f_path.mnt = nd->path.mnt; 33580fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 335944907d79SAl Viro open_to_namei_flags(open_flag), mode); 33606fbd0714SAl Viro d_lookup_done(dentry); 3361384f26e2SAl Viro if (!error) { 336264e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 33636fb968cdSAl Viro if (unlikely(dentry != file->f_path.dentry)) { 33646fb968cdSAl Viro dput(dentry); 33656fb968cdSAl Viro dentry = dget(file->f_path.dentry); 33666fb968cdSAl Viro } 336764e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 33682675a4ebSAl Viro error = -EIO; 3369384f26e2SAl Viro } else { 337030d90494SAl Viro if (file->f_path.dentry) { 3371d18e9008SMiklos Szeredi dput(dentry); 3372d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 337310c64ceaSAl Viro } 3374239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 3375a01e718fSAl Viro error = -ENOENT; 3376d18e9008SMiklos Szeredi } 3377d18e9008SMiklos Szeredi } 3378239eb983SAl Viro if (error) { 3379d18e9008SMiklos Szeredi dput(dentry); 3380239eb983SAl Viro dentry = ERR_PTR(error); 3381239eb983SAl Viro } 3382239eb983SAl Viro return dentry; 3383d18e9008SMiklos Szeredi } 3384d18e9008SMiklos Szeredi 338531e6b01fSNick Piggin /* 33861acf0af9SDavid Howells * Look up and maybe create and open the last component. 3387d58ffd35SMiklos Szeredi * 338800a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3389d58ffd35SMiklos Szeredi * 339000a07c15SAl Viro * Returns 0 on success, that is, if 339100a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 339200a07c15SAl Viro * the file was not completely opened at this time, though lookups and 339300a07c15SAl Viro * creations were performed. 339400a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 339500a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 339600a07c15SAl Viro * hadn't been specified. 33971acf0af9SDavid Howells * 339800a07c15SAl Viro * An error code is returned on failure. 3399d58ffd35SMiklos Szeredi */ 3400da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 3401d58ffd35SMiklos Szeredi const struct open_flags *op, 34023ec2eef1SAl Viro bool got_write) 3403d58ffd35SMiklos Szeredi { 34046c960e68SChristian Brauner struct mnt_idmap *idmap; 3405d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 340654ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 34071643b43fSAl Viro int open_flag = op->open_flag; 3408d58ffd35SMiklos Szeredi struct dentry *dentry; 34091643b43fSAl Viro int error, create_error = 0; 34101643b43fSAl Viro umode_t mode = op->mode; 34116fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3412d58ffd35SMiklos Szeredi 3413ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3414da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 3415d58ffd35SMiklos Szeredi 341673a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 34176fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 34186fbd0714SAl Viro for (;;) { 34196fbd0714SAl Viro if (!dentry) { 34206fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3421d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 3422da5ebf5aSAl Viro return dentry; 34236fbd0714SAl Viro } 34246fbd0714SAl Viro if (d_in_lookup(dentry)) 34256fbd0714SAl Viro break; 3426d58ffd35SMiklos Szeredi 34276fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 34286fbd0714SAl Viro if (likely(error > 0)) 34296fbd0714SAl Viro break; 34306fbd0714SAl Viro if (error) 34316fbd0714SAl Viro goto out_dput; 34326fbd0714SAl Viro d_invalidate(dentry); 34336fbd0714SAl Viro dput(dentry); 34346fbd0714SAl Viro dentry = NULL; 34356fbd0714SAl Viro } 34366fbd0714SAl Viro if (dentry->d_inode) { 3437d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3438da5ebf5aSAl Viro return dentry; 34396c51e513SAl Viro } 3440d18e9008SMiklos Szeredi 34411643b43fSAl Viro /* 34421643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 34431643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 34441643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 34451643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 34461643b43fSAl Viro * 34471643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 34481643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 34491643b43fSAl Viro */ 345099a4a90cSAl Viro if (unlikely(!got_write)) 345199a4a90cSAl Viro open_flag &= ~O_TRUNC; 34526c960e68SChristian Brauner idmap = mnt_idmap(nd->path.mnt); 34531643b43fSAl Viro if (open_flag & O_CREAT) { 345499a4a90cSAl Viro if (open_flag & O_EXCL) 345599a4a90cSAl Viro open_flag &= ~O_TRUNC; 34569452e93eSChristian Brauner mode = vfs_prepare_mode(idmap, dir->d_inode, mode, mode, mode); 345799a4a90cSAl Viro if (likely(got_write)) 34584609e1f1SChristian Brauner create_error = may_o_create(idmap, &nd->path, 3459ba73d987SChristian Brauner dentry, mode); 346099a4a90cSAl Viro else 346199a4a90cSAl Viro create_error = -EROFS; 346299a4a90cSAl Viro } 346399a4a90cSAl Viro if (create_error) 34641643b43fSAl Viro open_flag &= ~O_CREAT; 34651643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3466d489cf9aSAl Viro dentry = atomic_open(nd, dentry, file, open_flag, mode); 3467da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3468da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3469da5ebf5aSAl Viro return dentry; 3470239eb983SAl Viro } 347154ef4872SMiklos Szeredi 34726fbd0714SAl Viro if (d_in_lookup(dentry)) { 347312fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 347412fa5e24SAl Viro nd->flags); 34756fbd0714SAl Viro d_lookup_done(dentry); 347612fa5e24SAl Viro if (unlikely(res)) { 347712fa5e24SAl Viro if (IS_ERR(res)) { 347812fa5e24SAl Viro error = PTR_ERR(res); 347912fa5e24SAl Viro goto out_dput; 348012fa5e24SAl Viro } 348112fa5e24SAl Viro dput(dentry); 348212fa5e24SAl Viro dentry = res; 348312fa5e24SAl Viro } 348454ef4872SMiklos Szeredi } 348554ef4872SMiklos Szeredi 3486d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 34871643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 348873a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3489ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3490ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3491ce8644fcSAl Viro error = -EACCES; 3492d58ffd35SMiklos Szeredi goto out_dput; 349364894cf8SAl Viro } 3494549c7297SChristian Brauner 34956c960e68SChristian Brauner error = dir_inode->i_op->create(idmap, dir_inode, dentry, 3496549c7297SChristian Brauner mode, open_flag & O_EXCL); 3497d58ffd35SMiklos Szeredi if (error) 3498d58ffd35SMiklos Szeredi goto out_dput; 3499d58ffd35SMiklos Szeredi } 35001643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 35011643b43fSAl Viro error = create_error; 3502d58ffd35SMiklos Szeredi goto out_dput; 3503d58ffd35SMiklos Szeredi } 3504da5ebf5aSAl Viro return dentry; 3505d58ffd35SMiklos Szeredi 3506d58ffd35SMiklos Szeredi out_dput: 3507d58ffd35SMiklos Szeredi dput(dentry); 3508da5ebf5aSAl Viro return ERR_PTR(error); 3509d58ffd35SMiklos Szeredi } 3510d58ffd35SMiklos Szeredi 3511c981a482SAl Viro static const char *open_last_lookups(struct nameidata *nd, 35123ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3513fb1cc555SAl Viro { 3514a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3515ca344a89SAl Viro int open_flag = op->open_flag; 351664894cf8SAl Viro bool got_write = false; 3517da5ebf5aSAl Viro struct dentry *dentry; 3518b0417d2cSAl Viro const char *res; 3519fb1cc555SAl Viro 3520c3e380b0SAl Viro nd->flags |= op->intent; 3521c3e380b0SAl Viro 3522bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 352356676ec3SAl Viro if (nd->depth) 352456676ec3SAl Viro put_link(nd); 3525ff326a32SAl Viro return handle_dots(nd, nd->last_type); 35261f36f774SAl Viro } 3527a2c36b45SAl Viro 3528ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3529fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3530fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3531fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 35324cb64024SAl Viro dentry = lookup_fast(nd); 353320e34357SAl Viro if (IS_ERR(dentry)) 35341ccac622SAl Viro return ERR_CAST(dentry); 353520e34357SAl Viro if (likely(dentry)) 353671574865SMiklos Szeredi goto finish_lookup; 353771574865SMiklos Szeredi 35386583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3539b6183df7SMiklos Szeredi } else { 3540fe2d35ffSAl Viro /* create side of things */ 354172287417SAl Viro if (nd->flags & LOOKUP_RCU) { 3542e36cffedSJens Axboe if (!try_to_unlazy(nd)) 3543e36cffedSJens Axboe return ERR_PTR(-ECHILD); 354472287417SAl Viro } 3545c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 35461f36f774SAl Viro /* trailing slashes? */ 3547deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 35481ccac622SAl Viro return ERR_PTR(-EISDIR); 3549b6183df7SMiklos Szeredi } 35501f36f774SAl Viro 35519cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 3552e36cffedSJens Axboe got_write = !mnt_want_write(nd->path.mnt); 355364894cf8SAl Viro /* 355464894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 355564894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 355664894cf8SAl Viro * dropping this one anyway. 355764894cf8SAl Viro */ 355864894cf8SAl Viro } 35599cf843e3SAl Viro if (open_flag & O_CREAT) 35605955102cSAl Viro inode_lock(dir->d_inode); 35619cf843e3SAl Viro else 35629cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3563da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 3564f7bb959dSAl Viro if (!IS_ERR(dentry) && (file->f_mode & FMODE_CREATED)) 3565f7bb959dSAl Viro fsnotify_create(dir->d_inode, dentry); 35669cf843e3SAl Viro if (open_flag & O_CREAT) 35675955102cSAl Viro inode_unlock(dir->d_inode); 35689cf843e3SAl Viro else 35699cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3570fb1cc555SAl Viro 3571c981a482SAl Viro if (got_write) 357259e96e65SAl Viro mnt_drop_write(nd->path.mnt); 35736c0d46c4SAl Viro 357459e96e65SAl Viro if (IS_ERR(dentry)) 357559e96e65SAl Viro return ERR_CAST(dentry); 357659e96e65SAl Viro 3577973d4b73SAl Viro if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) { 3578e73cabffSAl Viro dput(nd->path.dentry); 3579e73cabffSAl Viro nd->path.dentry = dentry; 3580c981a482SAl Viro return NULL; 3581fb1cc555SAl Viro } 3582fb1cc555SAl Viro 358320e34357SAl Viro finish_lookup: 358456676ec3SAl Viro if (nd->depth) 358556676ec3SAl Viro put_link(nd); 3586a4f5b521SAl Viro res = step_into(nd, WALK_TRAILING, dentry); 3587ff326a32SAl Viro if (unlikely(res)) 35881ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3589b0417d2cSAl Viro return res; 35901ccac622SAl Viro } 359131d1726dSAl Viro 3592c981a482SAl Viro /* 3593c981a482SAl Viro * Handle the last step of open() 3594c981a482SAl Viro */ 3595c5971b8cSAl Viro static int do_open(struct nameidata *nd, 3596c981a482SAl Viro struct file *file, const struct open_flags *op) 3597c981a482SAl Viro { 3598abf08576SChristian Brauner struct mnt_idmap *idmap; 3599c981a482SAl Viro int open_flag = op->open_flag; 3600c981a482SAl Viro bool do_truncate; 3601c981a482SAl Viro int acc_mode; 3602c981a482SAl Viro int error; 3603c981a482SAl Viro 3604ff326a32SAl Viro if (!(file->f_mode & (FMODE_OPENED | FMODE_CREATED))) { 3605ff326a32SAl Viro error = complete_walk(nd); 3606ff326a32SAl Viro if (error) 3607ff326a32SAl Viro return error; 3608ff326a32SAl Viro } 3609973d4b73SAl Viro if (!(file->f_mode & FMODE_CREATED)) 361076ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3611abf08576SChristian Brauner idmap = mnt_idmap(nd->path.mnt); 361230aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3613b94e0b32SAl Viro if ((open_flag & O_EXCL) && !(file->f_mode & FMODE_CREATED)) 3614b94e0b32SAl Viro return -EEXIST; 361530aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 3616c5971b8cSAl Viro return -EISDIR; 3617e67fe633SChristian Brauner error = may_create_in_sticky(idmap, nd, 361830aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 361930aba665SSalvatore Mesoraca if (unlikely(error)) 3620c5971b8cSAl Viro return error; 362130aba665SSalvatore Mesoraca } 362244b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 3623c5971b8cSAl Viro return -ENOTDIR; 36246c0d46c4SAl Viro 36258795e7d4SAl Viro do_truncate = false; 36268795e7d4SAl Viro acc_mode = op->acc_mode; 36275a2d3eddSAl Viro if (file->f_mode & FMODE_CREATED) { 36285a2d3eddSAl Viro /* Don't check for write permission, don't truncate */ 36295a2d3eddSAl Viro open_flag &= ~O_TRUNC; 36305a2d3eddSAl Viro acc_mode = 0; 36318795e7d4SAl Viro } else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) { 36320f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 36330f9d1a10SAl Viro if (error) 3634c5971b8cSAl Viro return error; 36358795e7d4SAl Viro do_truncate = true; 36360f9d1a10SAl Viro } 36374609e1f1SChristian Brauner error = may_open(idmap, &nd->path, acc_mode, open_flag); 36388795e7d4SAl Viro if (!error && !(file->f_mode & FMODE_OPENED)) 3639ae2bb293SAl Viro error = vfs_open(&nd->path, file); 36408795e7d4SAl Viro if (!error) 36416035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 36428795e7d4SAl Viro if (!error && do_truncate) 3643abf08576SChristian Brauner error = handle_truncate(idmap, file); 3644c80567c8SAl Viro if (unlikely(error > 0)) { 3645c80567c8SAl Viro WARN_ON(1); 3646c80567c8SAl Viro error = -EINVAL; 3647c80567c8SAl Viro } 36488795e7d4SAl Viro if (do_truncate) 36490f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 3650c5971b8cSAl Viro return error; 3651fb1cc555SAl Viro } 3652fb1cc555SAl Viro 36536521f891SChristian Brauner /** 36546521f891SChristian Brauner * vfs_tmpfile - create tmpfile 3655abf08576SChristian Brauner * @idmap: idmap of the mount the inode was found from 365673bb5a90SRoberto Sassu * @parentpath: pointer to the path of the base directory 365773bb5a90SRoberto Sassu * @file: file descriptor of the new tmpfile 36586521f891SChristian Brauner * @mode: mode of the new tmpfile 36596521f891SChristian Brauner * 36606521f891SChristian Brauner * Create a temporary file. 36616521f891SChristian Brauner * 3662abf08576SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 3663abf08576SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 3664abf08576SChristian Brauner * care to map the inode according to @idmap before checking permissions. 36656521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 3666abf08576SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 36676521f891SChristian Brauner */ 3668abf08576SChristian Brauner static int vfs_tmpfile(struct mnt_idmap *idmap, 36699751b338SMiklos Szeredi const struct path *parentpath, 36709751b338SMiklos Szeredi struct file *file, umode_t mode) 3671af7bd4dcSAmir Goldstein { 36729751b338SMiklos Szeredi struct dentry *child; 36739751b338SMiklos Szeredi struct inode *dir = d_inode(parentpath->dentry); 3674af7bd4dcSAmir Goldstein struct inode *inode; 3675af7bd4dcSAmir Goldstein int error; 3676406c706cSPeter Griffin int open_flag = file->f_flags; 3677af7bd4dcSAmir Goldstein 3678af7bd4dcSAmir Goldstein /* we want directory to be writable */ 36794609e1f1SChristian Brauner error = inode_permission(idmap, dir, MAY_WRITE | MAY_EXEC); 3680af7bd4dcSAmir Goldstein if (error) 36819751b338SMiklos Szeredi return error; 3682af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 36839751b338SMiklos Szeredi return -EOPNOTSUPP; 36849751b338SMiklos Szeredi child = d_alloc(parentpath->dentry, &slash_name); 3685af7bd4dcSAmir Goldstein if (unlikely(!child)) 36869751b338SMiklos Szeredi return -ENOMEM; 36879751b338SMiklos Szeredi file->f_path.mnt = parentpath->mnt; 36889751b338SMiklos Szeredi file->f_path.dentry = child; 36899452e93eSChristian Brauner mode = vfs_prepare_mode(idmap, dir, mode, mode, mode); 3690011e2b71SChristian Brauner error = dir->i_op->tmpfile(idmap, dir, file, mode); 36919751b338SMiklos Szeredi dput(child); 3692af7bd4dcSAmir Goldstein if (error) 36939751b338SMiklos Szeredi return error; 36949751b338SMiklos Szeredi /* Don't check for other permissions, the inode was just created */ 36954609e1f1SChristian Brauner error = may_open(idmap, &file->f_path, 0, file->f_flags); 36969751b338SMiklos Szeredi if (error) 36979751b338SMiklos Szeredi return error; 36989751b338SMiklos Szeredi inode = file_inode(file); 3699406c706cSPeter Griffin if (!(open_flag & O_EXCL)) { 3700af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3701af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3702af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3703af7bd4dcSAmir Goldstein } 370439f60c1cSChristian Brauner ima_post_create_tmpfile(idmap, inode); 37059751b338SMiklos Szeredi return 0; 3706af7bd4dcSAmir Goldstein } 3707af7bd4dcSAmir Goldstein 370822873deaSMiklos Szeredi /** 3709d56e0ddbSAmir Goldstein * kernel_tmpfile_open - open a tmpfile for kernel internal use 3710abf08576SChristian Brauner * @idmap: idmap of the mount the inode was found from 371122873deaSMiklos Szeredi * @parentpath: path of the base directory 371222873deaSMiklos Szeredi * @mode: mode of the new tmpfile 371322873deaSMiklos Szeredi * @open_flag: flags 371422873deaSMiklos Szeredi * @cred: credentials for open 371522873deaSMiklos Szeredi * 371622873deaSMiklos Szeredi * Create and open a temporary file. The file is not accounted in nr_files, 371722873deaSMiklos Szeredi * hence this is only for kernel internal use, and must not be installed into 371822873deaSMiklos Szeredi * file tables or such. 371922873deaSMiklos Szeredi */ 3720d56e0ddbSAmir Goldstein struct file *kernel_tmpfile_open(struct mnt_idmap *idmap, 372122873deaSMiklos Szeredi const struct path *parentpath, 3722d56e0ddbSAmir Goldstein umode_t mode, int open_flag, 3723d56e0ddbSAmir Goldstein const struct cred *cred) 372422873deaSMiklos Szeredi { 372522873deaSMiklos Szeredi struct file *file; 372622873deaSMiklos Szeredi int error; 372722873deaSMiklos Szeredi 37289751b338SMiklos Szeredi file = alloc_empty_file_noaccount(open_flag, cred); 3729d56e0ddbSAmir Goldstein if (IS_ERR(file)) 3730d56e0ddbSAmir Goldstein return file; 3731d56e0ddbSAmir Goldstein 3732abf08576SChristian Brauner error = vfs_tmpfile(idmap, parentpath, file, mode); 37339751b338SMiklos Szeredi if (error) { 37349751b338SMiklos Szeredi fput(file); 373522873deaSMiklos Szeredi file = ERR_PTR(error); 37369751b338SMiklos Szeredi } 373722873deaSMiklos Szeredi return file; 373822873deaSMiklos Szeredi } 3739d56e0ddbSAmir Goldstein EXPORT_SYMBOL(kernel_tmpfile_open); 3740648fa861SAl Viro 3741c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 374260545d0dSAl Viro const struct open_flags *op, 37433ec2eef1SAl Viro struct file *file) 374460545d0dSAl Viro { 3745625b6d10SAl Viro struct path path; 3746c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 37479751b338SMiklos Szeredi 374860545d0dSAl Viro if (unlikely(error)) 374960545d0dSAl Viro return error; 3750625b6d10SAl Viro error = mnt_want_write(path.mnt); 375160545d0dSAl Viro if (unlikely(error)) 375260545d0dSAl Viro goto out; 3753abf08576SChristian Brauner error = vfs_tmpfile(mnt_idmap(path.mnt), &path, file, op->mode); 37549751b338SMiklos Szeredi if (error) 375560545d0dSAl Viro goto out2; 37569751b338SMiklos Szeredi audit_inode(nd->name, file->f_path.dentry, 0); 375760545d0dSAl Viro out2: 3758625b6d10SAl Viro mnt_drop_write(path.mnt); 375960545d0dSAl Viro out: 3760625b6d10SAl Viro path_put(&path); 376160545d0dSAl Viro return error; 376260545d0dSAl Viro } 376360545d0dSAl Viro 37646ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 37656ac08709SAl Viro { 37666ac08709SAl Viro struct path path; 37676ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 37686ac08709SAl Viro if (!error) { 37696ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3770ae2bb293SAl Viro error = vfs_open(&path, file); 37716ac08709SAl Viro path_put(&path); 37726ac08709SAl Viro } 37736ac08709SAl Viro return error; 37746ac08709SAl Viro } 37756ac08709SAl Viro 3776c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3777c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 37781da177e4SLinus Torvalds { 377930d90494SAl Viro struct file *file; 378013aab428SAl Viro int error; 378131e6b01fSNick Piggin 3782ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 37831afc99beSAl Viro if (IS_ERR(file)) 37841afc99beSAl Viro return file; 378531e6b01fSNick Piggin 3786bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 37873ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 37885f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 37896ac08709SAl Viro error = do_o_path(nd, flags, file); 37905f336e72SAl Viro } else { 37915f336e72SAl Viro const char *s = path_init(nd, flags); 37923bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 3793c5971b8cSAl Viro (s = open_last_lookups(nd, file, op)) != NULL) 37941ccac622SAl Viro ; 3795c5971b8cSAl Viro if (!error) 3796c5971b8cSAl Viro error = do_open(nd, file, op); 3797deb106c6SAl Viro terminate_walk(nd); 37985f336e72SAl Viro } 37997c1c01ecSAl Viro if (likely(!error)) { 3800aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 38017c1c01ecSAl Viro return file; 38027c1c01ecSAl Viro WARN_ON(1); 38037c1c01ecSAl Viro error = -EINVAL; 3804015c3bbcSMiklos Szeredi } 38057c1c01ecSAl Viro fput(file); 38062675a4ebSAl Viro if (error == -EOPENSTALE) { 38072675a4ebSAl Viro if (flags & LOOKUP_RCU) 38082675a4ebSAl Viro error = -ECHILD; 38092675a4ebSAl Viro else 38102675a4ebSAl Viro error = -ESTALE; 38112675a4ebSAl Viro } 38127c1c01ecSAl Viro return ERR_PTR(error); 3813de459215SKirill Korotaev } 38141da177e4SLinus Torvalds 3815669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3816f9652e10SAl Viro const struct open_flags *op) 381713aab428SAl Viro { 38189883d185SAl Viro struct nameidata nd; 3819f9652e10SAl Viro int flags = op->lookup_flags; 382013aab428SAl Viro struct file *filp; 382113aab428SAl Viro 382206422964SAl Viro set_nameidata(&nd, dfd, pathname, NULL); 3823c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 382413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3825c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 382613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3827c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 38289883d185SAl Viro restore_nameidata(); 382913aab428SAl Viro return filp; 383013aab428SAl Viro } 383113aab428SAl Viro 3832ffb37ca3SAl Viro struct file *do_file_open_root(const struct path *root, 3833f9652e10SAl Viro const char *name, const struct open_flags *op) 383473d049a4SAl Viro { 38359883d185SAl Viro struct nameidata nd; 383673d049a4SAl Viro struct file *file; 383751689104SPaul Moore struct filename *filename; 3838bcba1e7dSAl Viro int flags = op->lookup_flags; 383973d049a4SAl Viro 3840ffb37ca3SAl Viro if (d_is_symlink(root->dentry) && op->intent & LOOKUP_OPEN) 384173d049a4SAl Viro return ERR_PTR(-ELOOP); 384273d049a4SAl Viro 384351689104SPaul Moore filename = getname_kernel(name); 3844a1c83681SViresh Kumar if (IS_ERR(filename)) 384551689104SPaul Moore return ERR_CAST(filename); 384651689104SPaul Moore 384706422964SAl Viro set_nameidata(&nd, -1, filename, root); 3848c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 384973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3850c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 385173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3852c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 38539883d185SAl Viro restore_nameidata(); 385451689104SPaul Moore putname(filename); 385573d049a4SAl Viro return file; 385673d049a4SAl Viro } 385773d049a4SAl Viro 3858b4a4f213SStephen Brennan static struct dentry *filename_create(int dfd, struct filename *name, 38591ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 38601da177e4SLinus Torvalds { 3861c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3862391172c4SAl Viro struct qstr last; 3863b3d4650dSNeilBrown bool want_dir = lookup_flags & LOOKUP_DIRECTORY; 3864b3d4650dSNeilBrown unsigned int reval_flag = lookup_flags & LOOKUP_REVAL; 3865b3d4650dSNeilBrown unsigned int create_flags = LOOKUP_CREATE | LOOKUP_EXCL; 3866391172c4SAl Viro int type; 3867c30dabfeSJan Kara int err2; 38681ac12b4bSJeff Layton int error; 38691ac12b4bSJeff Layton 3870b3d4650dSNeilBrown error = filename_parentat(dfd, name, reval_flag, path, &last, &type); 38710ee50b47SDmitry Kadashev if (error) 38720ee50b47SDmitry Kadashev return ERR_PTR(error); 38731da177e4SLinus Torvalds 3874c663e5d8SChristoph Hellwig /* 3875c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3876c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3877c663e5d8SChristoph Hellwig */ 38785c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3879ed75e95dSAl Viro goto out; 3880c663e5d8SChristoph Hellwig 3881c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3882391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3883c663e5d8SChristoph Hellwig /* 3884b3d4650dSNeilBrown * Do the final lookup. Suppress 'create' if there is a trailing 3885b3d4650dSNeilBrown * '/', and a directory wasn't requested. 3886c663e5d8SChristoph Hellwig */ 3887b3d4650dSNeilBrown if (last.name[last.len] && !want_dir) 3888b3d4650dSNeilBrown create_flags = 0; 38895955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 389074d7970fSNamjae Jeon dentry = lookup_one_qstr_excl(&last, path->dentry, 389174d7970fSNamjae Jeon reval_flag | create_flags); 38921da177e4SLinus Torvalds if (IS_ERR(dentry)) 3893a8104a9fSAl Viro goto unlock; 3894c663e5d8SChristoph Hellwig 3895a8104a9fSAl Viro error = -EEXIST; 3896b18825a7SDavid Howells if (d_is_positive(dentry)) 3897a8104a9fSAl Viro goto fail; 3898b18825a7SDavid Howells 3899c663e5d8SChristoph Hellwig /* 3900c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3901c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3902c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3903c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3904c663e5d8SChristoph Hellwig */ 3905b3d4650dSNeilBrown if (unlikely(!create_flags)) { 3906a8104a9fSAl Viro error = -ENOENT; 3907ed75e95dSAl Viro goto fail; 3908e9baf6e5SAl Viro } 3909c30dabfeSJan Kara if (unlikely(err2)) { 3910c30dabfeSJan Kara error = err2; 3911a8104a9fSAl Viro goto fail; 3912c30dabfeSJan Kara } 3913e9baf6e5SAl Viro return dentry; 39141da177e4SLinus Torvalds fail: 3915a8104a9fSAl Viro dput(dentry); 3916a8104a9fSAl Viro dentry = ERR_PTR(error); 3917a8104a9fSAl Viro unlock: 39185955102cSAl Viro inode_unlock(path->dentry->d_inode); 3919c30dabfeSJan Kara if (!err2) 3920391172c4SAl Viro mnt_drop_write(path->mnt); 3921ed75e95dSAl Viro out: 3922391172c4SAl Viro path_put(path); 3923ed75e95dSAl Viro return dentry; 3924dae6ad8fSAl Viro } 3925fa14a0b8SAl Viro 3926fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3927fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3928fa14a0b8SAl Viro { 3929b4a4f213SStephen Brennan struct filename *filename = getname_kernel(pathname); 3930b4a4f213SStephen Brennan struct dentry *res = filename_create(dfd, filename, path, lookup_flags); 3931b4a4f213SStephen Brennan 3932b4a4f213SStephen Brennan putname(filename); 3933b4a4f213SStephen Brennan return res; 3934fa14a0b8SAl Viro } 3935dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3936dae6ad8fSAl Viro 3937921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3938921a1650SAl Viro { 3939921a1650SAl Viro dput(dentry); 39405955102cSAl Viro inode_unlock(path->dentry->d_inode); 3941a8104a9fSAl Viro mnt_drop_write(path->mnt); 3942921a1650SAl Viro path_put(path); 3943921a1650SAl Viro } 3944921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3945921a1650SAl Viro 3946520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 39471ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3948dae6ad8fSAl Viro { 3949b4a4f213SStephen Brennan struct filename *filename = getname(pathname); 3950b4a4f213SStephen Brennan struct dentry *res = filename_create(dfd, filename, path, lookup_flags); 3951b4a4f213SStephen Brennan 3952b4a4f213SStephen Brennan putname(filename); 3953b4a4f213SStephen Brennan return res; 3954dae6ad8fSAl Viro } 3955dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3956dae6ad8fSAl Viro 39576521f891SChristian Brauner /** 39586521f891SChristian Brauner * vfs_mknod - create device node or file 3959abf08576SChristian Brauner * @idmap: idmap of the mount the inode was found from 39606521f891SChristian Brauner * @dir: inode of @dentry 39616521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 39626521f891SChristian Brauner * @mode: mode of the new device node or file 39636521f891SChristian Brauner * @dev: device number of device to create 39646521f891SChristian Brauner * 39656521f891SChristian Brauner * Create a device node or file. 39666521f891SChristian Brauner * 3967abf08576SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 3968abf08576SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 3969abf08576SChristian Brauner * care to map the inode according to @idmap before checking permissions. 39706521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 3971abf08576SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 39726521f891SChristian Brauner */ 3973abf08576SChristian Brauner int vfs_mknod(struct mnt_idmap *idmap, struct inode *dir, 39746521f891SChristian Brauner struct dentry *dentry, umode_t mode, dev_t dev) 39751da177e4SLinus Torvalds { 3976a3c751a5SMiklos Szeredi bool is_whiteout = S_ISCHR(mode) && dev == WHITEOUT_DEV; 39774609e1f1SChristian Brauner int error = may_create(idmap, dir, dentry); 39781da177e4SLinus Torvalds 39791da177e4SLinus Torvalds if (error) 39801da177e4SLinus Torvalds return error; 39811da177e4SLinus Torvalds 3982a3c751a5SMiklos Szeredi if ((S_ISCHR(mode) || S_ISBLK(mode)) && !is_whiteout && 3983a3c751a5SMiklos Szeredi !capable(CAP_MKNOD)) 39841da177e4SLinus Torvalds return -EPERM; 39851da177e4SLinus Torvalds 3986acfa4380SAl Viro if (!dir->i_op->mknod) 39871da177e4SLinus Torvalds return -EPERM; 39881da177e4SLinus Torvalds 39899452e93eSChristian Brauner mode = vfs_prepare_mode(idmap, dir, mode, mode, mode); 399008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 399108ce5f16SSerge E. Hallyn if (error) 399208ce5f16SSerge E. Hallyn return error; 399308ce5f16SSerge E. Hallyn 39941da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 39951da177e4SLinus Torvalds if (error) 39961da177e4SLinus Torvalds return error; 39971da177e4SLinus Torvalds 39985ebb29beSChristian Brauner error = dir->i_op->mknod(idmap, dir, dentry, mode, dev); 3999a74574aaSStephen Smalley if (!error) 4000f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40011da177e4SLinus Torvalds return error; 40021da177e4SLinus Torvalds } 40034d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 40041da177e4SLinus Torvalds 4005f69aac00SAl Viro static int may_mknod(umode_t mode) 4006463c3197SDave Hansen { 4007463c3197SDave Hansen switch (mode & S_IFMT) { 4008463c3197SDave Hansen case S_IFREG: 4009463c3197SDave Hansen case S_IFCHR: 4010463c3197SDave Hansen case S_IFBLK: 4011463c3197SDave Hansen case S_IFIFO: 4012463c3197SDave Hansen case S_IFSOCK: 4013463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 4014463c3197SDave Hansen return 0; 4015463c3197SDave Hansen case S_IFDIR: 4016463c3197SDave Hansen return -EPERM; 4017463c3197SDave Hansen default: 4018463c3197SDave Hansen return -EINVAL; 4019463c3197SDave Hansen } 4020463c3197SDave Hansen } 4021463c3197SDave Hansen 402245f30dabSDmitry Kadashev static int do_mknodat(int dfd, struct filename *name, umode_t mode, 402387c4e192SDominik Brodowski unsigned int dev) 40241da177e4SLinus Torvalds { 4025abf08576SChristian Brauner struct mnt_idmap *idmap; 40261da177e4SLinus Torvalds struct dentry *dentry; 4027dae6ad8fSAl Viro struct path path; 4028dae6ad8fSAl Viro int error; 4029972567f1SJeff Layton unsigned int lookup_flags = 0; 40301da177e4SLinus Torvalds 40318e4bfca1SAl Viro error = may_mknod(mode); 40328e4bfca1SAl Viro if (error) 40337797251bSDmitry Kadashev goto out1; 4034972567f1SJeff Layton retry: 4035b4a4f213SStephen Brennan dentry = filename_create(dfd, name, &path, lookup_flags); 40367797251bSDmitry Kadashev error = PTR_ERR(dentry); 4037dae6ad8fSAl Viro if (IS_ERR(dentry)) 40387797251bSDmitry Kadashev goto out1; 40392ad94ae6SAl Viro 40401639a49cSYang Xu error = security_path_mknod(&path, dentry, 40411639a49cSYang Xu mode_strip_umask(path.dentry->d_inode, mode), dev); 4042be6d3e56SKentaro Takeda if (error) 40437797251bSDmitry Kadashev goto out2; 40446521f891SChristian Brauner 4045abf08576SChristian Brauner idmap = mnt_idmap(path.mnt); 40461da177e4SLinus Torvalds switch (mode & S_IFMT) { 40471da177e4SLinus Torvalds case 0: case S_IFREG: 4048abf08576SChristian Brauner error = vfs_create(idmap, path.dentry->d_inode, 40496521f891SChristian Brauner dentry, mode, true); 405005d1a717SMimi Zohar if (!error) 405139f60c1cSChristian Brauner ima_post_path_mknod(idmap, dentry); 40521da177e4SLinus Torvalds break; 40531da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 4054abf08576SChristian Brauner error = vfs_mknod(idmap, path.dentry->d_inode, 40556521f891SChristian Brauner dentry, mode, new_decode_dev(dev)); 40561da177e4SLinus Torvalds break; 40571da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 4058abf08576SChristian Brauner error = vfs_mknod(idmap, path.dentry->d_inode, 40596521f891SChristian Brauner dentry, mode, 0); 40601da177e4SLinus Torvalds break; 40611da177e4SLinus Torvalds } 40627797251bSDmitry Kadashev out2: 4063921a1650SAl Viro done_path_create(&path, dentry); 4064972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 4065972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 4066972567f1SJeff Layton goto retry; 4067972567f1SJeff Layton } 40687797251bSDmitry Kadashev out1: 40697797251bSDmitry Kadashev putname(name); 40701da177e4SLinus Torvalds return error; 40711da177e4SLinus Torvalds } 40721da177e4SLinus Torvalds 407387c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 407487c4e192SDominik Brodowski unsigned int, dev) 407587c4e192SDominik Brodowski { 40767797251bSDmitry Kadashev return do_mknodat(dfd, getname(filename), mode, dev); 407787c4e192SDominik Brodowski } 407887c4e192SDominik Brodowski 40798208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 40805590ff0dSUlrich Drepper { 40817797251bSDmitry Kadashev return do_mknodat(AT_FDCWD, getname(filename), mode, dev); 40825590ff0dSUlrich Drepper } 40835590ff0dSUlrich Drepper 40846521f891SChristian Brauner /** 40856521f891SChristian Brauner * vfs_mkdir - create directory 4086abf08576SChristian Brauner * @idmap: idmap of the mount the inode was found from 40876521f891SChristian Brauner * @dir: inode of @dentry 40886521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 40896521f891SChristian Brauner * @mode: mode of the new directory 40906521f891SChristian Brauner * 40916521f891SChristian Brauner * Create a directory. 40926521f891SChristian Brauner * 4093abf08576SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 4094abf08576SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 4095abf08576SChristian Brauner * care to map the inode according to @idmap before checking permissions. 40966521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 4097abf08576SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 40986521f891SChristian Brauner */ 4099abf08576SChristian Brauner int vfs_mkdir(struct mnt_idmap *idmap, struct inode *dir, 41006521f891SChristian Brauner struct dentry *dentry, umode_t mode) 41011da177e4SLinus Torvalds { 4102abf08576SChristian Brauner int error; 41038de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41041da177e4SLinus Torvalds 41054609e1f1SChristian Brauner error = may_create(idmap, dir, dentry); 41061da177e4SLinus Torvalds if (error) 41071da177e4SLinus Torvalds return error; 41081da177e4SLinus Torvalds 4109acfa4380SAl Viro if (!dir->i_op->mkdir) 41101da177e4SLinus Torvalds return -EPERM; 41111da177e4SLinus Torvalds 41129452e93eSChristian Brauner mode = vfs_prepare_mode(idmap, dir, mode, S_IRWXUGO | S_ISVTX, 0); 41131da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 41141da177e4SLinus Torvalds if (error) 41151da177e4SLinus Torvalds return error; 41161da177e4SLinus Torvalds 41178de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 41188de52778SAl Viro return -EMLINK; 41198de52778SAl Viro 4120c54bd91eSChristian Brauner error = dir->i_op->mkdir(idmap, dir, dentry, mode); 4121a74574aaSStephen Smalley if (!error) 4122f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 41231da177e4SLinus Torvalds return error; 41241da177e4SLinus Torvalds } 41254d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 41261da177e4SLinus Torvalds 412745f30dabSDmitry Kadashev int do_mkdirat(int dfd, struct filename *name, umode_t mode) 41281da177e4SLinus Torvalds { 41296902d925SDave Hansen struct dentry *dentry; 4130dae6ad8fSAl Viro struct path path; 4131dae6ad8fSAl Viro int error; 4132b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 41331da177e4SLinus Torvalds 4134b76d8b82SJeff Layton retry: 4135b4a4f213SStephen Brennan dentry = filename_create(dfd, name, &path, lookup_flags); 4136584d3226SDmitry Kadashev error = PTR_ERR(dentry); 41376902d925SDave Hansen if (IS_ERR(dentry)) 4138584d3226SDmitry Kadashev goto out_putname; 41396902d925SDave Hansen 41401639a49cSYang Xu error = security_path_mkdir(&path, dentry, 41411639a49cSYang Xu mode_strip_umask(path.dentry->d_inode, mode)); 41426521f891SChristian Brauner if (!error) { 4143abf08576SChristian Brauner error = vfs_mkdir(mnt_idmap(path.mnt), path.dentry->d_inode, 4144abf08576SChristian Brauner dentry, mode); 41456521f891SChristian Brauner } 4146921a1650SAl Viro done_path_create(&path, dentry); 4147b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 4148b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 4149b76d8b82SJeff Layton goto retry; 4150b76d8b82SJeff Layton } 4151584d3226SDmitry Kadashev out_putname: 4152584d3226SDmitry Kadashev putname(name); 41531da177e4SLinus Torvalds return error; 41541da177e4SLinus Torvalds } 41551da177e4SLinus Torvalds 41560101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 41570101db7aSDominik Brodowski { 4158584d3226SDmitry Kadashev return do_mkdirat(dfd, getname(pathname), mode); 41590101db7aSDominik Brodowski } 41600101db7aSDominik Brodowski 4161a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 41625590ff0dSUlrich Drepper { 4163584d3226SDmitry Kadashev return do_mkdirat(AT_FDCWD, getname(pathname), mode); 41645590ff0dSUlrich Drepper } 41655590ff0dSUlrich Drepper 41666521f891SChristian Brauner /** 41676521f891SChristian Brauner * vfs_rmdir - remove directory 4168abf08576SChristian Brauner * @idmap: idmap of the mount the inode was found from 41696521f891SChristian Brauner * @dir: inode of @dentry 41706521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 41716521f891SChristian Brauner * 41726521f891SChristian Brauner * Remove a directory. 41736521f891SChristian Brauner * 4174abf08576SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 4175abf08576SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 4176abf08576SChristian Brauner * care to map the inode according to @idmap before checking permissions. 41776521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 4178abf08576SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 41796521f891SChristian Brauner */ 4180abf08576SChristian Brauner int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir, 41816521f891SChristian Brauner struct dentry *dentry) 41821da177e4SLinus Torvalds { 41834609e1f1SChristian Brauner int error = may_delete(idmap, dir, dentry, 1); 41841da177e4SLinus Torvalds 41851da177e4SLinus Torvalds if (error) 41861da177e4SLinus Torvalds return error; 41871da177e4SLinus Torvalds 4188acfa4380SAl Viro if (!dir->i_op->rmdir) 41891da177e4SLinus Torvalds return -EPERM; 41901da177e4SLinus Torvalds 41911d2ef590SAl Viro dget(dentry); 41925955102cSAl Viro inode_lock(dentry->d_inode); 4193912dbc15SSage Weil 41941da177e4SLinus Torvalds error = -EBUSY; 41951bd9c4e4SDavid Howells if (is_local_mountpoint(dentry) || 41961bd9c4e4SDavid Howells (dentry->d_inode->i_flags & S_KERNEL_FILE)) 4197912dbc15SSage Weil goto out; 4198912dbc15SSage Weil 41991da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 4200912dbc15SSage Weil if (error) 4201912dbc15SSage Weil goto out; 4202912dbc15SSage Weil 42031da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 4204912dbc15SSage Weil if (error) 4205912dbc15SSage Weil goto out; 4206912dbc15SSage Weil 42078767712fSAl Viro shrink_dcache_parent(dentry); 42081da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 4209d83c49f3SAl Viro dont_mount(dentry); 42108ed936b5SEric W. Biederman detach_mounts(dentry); 42111da177e4SLinus Torvalds 4212912dbc15SSage Weil out: 42135955102cSAl Viro inode_unlock(dentry->d_inode); 42141d2ef590SAl Viro dput(dentry); 4215912dbc15SSage Weil if (!error) 4216a37d9a17SAmir Goldstein d_delete_notify(dir, dentry); 42171da177e4SLinus Torvalds return error; 42181da177e4SLinus Torvalds } 42194d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 42201da177e4SLinus Torvalds 422145f30dabSDmitry Kadashev int do_rmdir(int dfd, struct filename *name) 42221da177e4SLinus Torvalds { 42230ee50b47SDmitry Kadashev int error; 42241da177e4SLinus Torvalds struct dentry *dentry; 4225f5beed75SAl Viro struct path path; 4226f5beed75SAl Viro struct qstr last; 4227f5beed75SAl Viro int type; 4228c6ee9206SJeff Layton unsigned int lookup_flags = 0; 4229c6ee9206SJeff Layton retry: 4230c5f563f9SAl Viro error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 42310ee50b47SDmitry Kadashev if (error) 42320ee50b47SDmitry Kadashev goto exit1; 42331da177e4SLinus Torvalds 4234f5beed75SAl Viro switch (type) { 42351da177e4SLinus Torvalds case LAST_DOTDOT: 42361da177e4SLinus Torvalds error = -ENOTEMPTY; 42370ee50b47SDmitry Kadashev goto exit2; 42381da177e4SLinus Torvalds case LAST_DOT: 42391da177e4SLinus Torvalds error = -EINVAL; 42400ee50b47SDmitry Kadashev goto exit2; 42411da177e4SLinus Torvalds case LAST_ROOT: 42421da177e4SLinus Torvalds error = -EBUSY; 42430ee50b47SDmitry Kadashev goto exit2; 42441da177e4SLinus Torvalds } 42450612d9fbSOGAWA Hirofumi 4246f5beed75SAl Viro error = mnt_want_write(path.mnt); 4247c30dabfeSJan Kara if (error) 42480ee50b47SDmitry Kadashev goto exit2; 42490612d9fbSOGAWA Hirofumi 42505955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 425174d7970fSNamjae Jeon dentry = lookup_one_qstr_excl(&last, path.dentry, lookup_flags); 42521da177e4SLinus Torvalds error = PTR_ERR(dentry); 42536902d925SDave Hansen if (IS_ERR(dentry)) 42540ee50b47SDmitry Kadashev goto exit3; 4255e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 4256e6bc45d6STheodore Ts'o error = -ENOENT; 42570ee50b47SDmitry Kadashev goto exit4; 4258e6bc45d6STheodore Ts'o } 4259f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 4260be6d3e56SKentaro Takeda if (error) 42610ee50b47SDmitry Kadashev goto exit4; 4262abf08576SChristian Brauner error = vfs_rmdir(mnt_idmap(path.mnt), path.dentry->d_inode, dentry); 42630ee50b47SDmitry Kadashev exit4: 42641da177e4SLinus Torvalds dput(dentry); 42650ee50b47SDmitry Kadashev exit3: 42665955102cSAl Viro inode_unlock(path.dentry->d_inode); 4267f5beed75SAl Viro mnt_drop_write(path.mnt); 42680ee50b47SDmitry Kadashev exit2: 4269f5beed75SAl Viro path_put(&path); 4270c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 4271c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 4272c6ee9206SJeff Layton goto retry; 4273c6ee9206SJeff Layton } 42740ee50b47SDmitry Kadashev exit1: 427524fb33d4SAl Viro putname(name); 42761da177e4SLinus Torvalds return error; 42771da177e4SLinus Torvalds } 42781da177e4SLinus Torvalds 42793cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 42805590ff0dSUlrich Drepper { 4281e24ab0efSChristoph Hellwig return do_rmdir(AT_FDCWD, getname(pathname)); 42825590ff0dSUlrich Drepper } 42835590ff0dSUlrich Drepper 4284b21996e3SJ. Bruce Fields /** 4285b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 4286abf08576SChristian Brauner * @idmap: idmap of the mount the inode was found from 4287b21996e3SJ. Bruce Fields * @dir: parent directory 4288b21996e3SJ. Bruce Fields * @dentry: victim 4289b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 4290b21996e3SJ. Bruce Fields * 4291b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 4292b21996e3SJ. Bruce Fields * 4293b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 4294b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 4295b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 4296b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 4297b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 4298b21996e3SJ. Bruce Fields * 4299b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4300b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4301b21996e3SJ. Bruce Fields * to be NFS exported. 43026521f891SChristian Brauner * 4303abf08576SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 4304abf08576SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 4305abf08576SChristian Brauner * care to map the inode according to @idmap before checking permissions. 43066521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 4307abf08576SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 4308b21996e3SJ. Bruce Fields */ 4309abf08576SChristian Brauner int vfs_unlink(struct mnt_idmap *idmap, struct inode *dir, 43106521f891SChristian Brauner struct dentry *dentry, struct inode **delegated_inode) 43111da177e4SLinus Torvalds { 43129accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 43134609e1f1SChristian Brauner int error = may_delete(idmap, dir, dentry, 0); 43141da177e4SLinus Torvalds 43151da177e4SLinus Torvalds if (error) 43161da177e4SLinus Torvalds return error; 43171da177e4SLinus Torvalds 4318acfa4380SAl Viro if (!dir->i_op->unlink) 43191da177e4SLinus Torvalds return -EPERM; 43201da177e4SLinus Torvalds 43215955102cSAl Viro inode_lock(target); 432251cc3a66SHugh Dickins if (IS_SWAPFILE(target)) 432351cc3a66SHugh Dickins error = -EPERM; 432451cc3a66SHugh Dickins else if (is_local_mountpoint(dentry)) 43251da177e4SLinus Torvalds error = -EBUSY; 43261da177e4SLinus Torvalds else { 43271da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 4328bec1052eSAl Viro if (!error) { 43295a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 43305a14696cSJ. Bruce Fields if (error) 4331b21996e3SJ. Bruce Fields goto out; 43321da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 43338ed936b5SEric W. Biederman if (!error) { 4334d83c49f3SAl Viro dont_mount(dentry); 43358ed936b5SEric W. Biederman detach_mounts(dentry); 43368ed936b5SEric W. Biederman } 4337bec1052eSAl Viro } 43381da177e4SLinus Torvalds } 4339b21996e3SJ. Bruce Fields out: 43405955102cSAl Viro inode_unlock(target); 43411da177e4SLinus Torvalds 43421da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 4343a37d9a17SAmir Goldstein if (!error && dentry->d_flags & DCACHE_NFSFS_RENAMED) { 4344a37d9a17SAmir Goldstein fsnotify_unlink(dir, dentry); 4345a37d9a17SAmir Goldstein } else if (!error) { 43469accbb97SJ. Bruce Fields fsnotify_link_count(target); 4347a37d9a17SAmir Goldstein d_delete_notify(dir, dentry); 43481da177e4SLinus Torvalds } 43490eeca283SRobert Love 43501da177e4SLinus Torvalds return error; 43511da177e4SLinus Torvalds } 43524d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 43531da177e4SLinus Torvalds 43541da177e4SLinus Torvalds /* 43551da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 43561b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 43571da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 43581da177e4SLinus Torvalds * while waiting on the I/O. 43591da177e4SLinus Torvalds */ 436045f30dabSDmitry Kadashev int do_unlinkat(int dfd, struct filename *name) 43611da177e4SLinus Torvalds { 43622ad94ae6SAl Viro int error; 43631da177e4SLinus Torvalds struct dentry *dentry; 4364f5beed75SAl Viro struct path path; 4365f5beed75SAl Viro struct qstr last; 4366f5beed75SAl Viro int type; 43671da177e4SLinus Torvalds struct inode *inode = NULL; 4368b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 43695d18f813SJeff Layton unsigned int lookup_flags = 0; 43705d18f813SJeff Layton retry: 4371c5f563f9SAl Viro error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 43720ee50b47SDmitry Kadashev if (error) 43730ee50b47SDmitry Kadashev goto exit1; 43742ad94ae6SAl Viro 43751da177e4SLinus Torvalds error = -EISDIR; 4376f5beed75SAl Viro if (type != LAST_NORM) 43770ee50b47SDmitry Kadashev goto exit2; 43780612d9fbSOGAWA Hirofumi 4379f5beed75SAl Viro error = mnt_want_write(path.mnt); 4380c30dabfeSJan Kara if (error) 43810ee50b47SDmitry Kadashev goto exit2; 4382b21996e3SJ. Bruce Fields retry_deleg: 43835955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 438474d7970fSNamjae Jeon dentry = lookup_one_qstr_excl(&last, path.dentry, lookup_flags); 43851da177e4SLinus Torvalds error = PTR_ERR(dentry); 43861da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 43876521f891SChristian Brauner 43881da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4389f5beed75SAl Viro if (last.name[last.len]) 439050338b88STörök Edwin goto slashes; 43911da177e4SLinus Torvalds inode = dentry->d_inode; 4392b18825a7SDavid Howells if (d_is_negative(dentry)) 4393e6bc45d6STheodore Ts'o goto slashes; 43947de9c6eeSAl Viro ihold(inode); 4395f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4396be6d3e56SKentaro Takeda if (error) 43970ee50b47SDmitry Kadashev goto exit3; 4398abf08576SChristian Brauner error = vfs_unlink(mnt_idmap(path.mnt), path.dentry->d_inode, 4399abf08576SChristian Brauner dentry, &delegated_inode); 44000ee50b47SDmitry Kadashev exit3: 44011da177e4SLinus Torvalds dput(dentry); 44021da177e4SLinus Torvalds } 44035955102cSAl Viro inode_unlock(path.dentry->d_inode); 44041da177e4SLinus Torvalds if (inode) 44051da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4406b21996e3SJ. Bruce Fields inode = NULL; 4407b21996e3SJ. Bruce Fields if (delegated_inode) { 44085a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4409b21996e3SJ. Bruce Fields if (!error) 4410b21996e3SJ. Bruce Fields goto retry_deleg; 4411b21996e3SJ. Bruce Fields } 4412f5beed75SAl Viro mnt_drop_write(path.mnt); 44130ee50b47SDmitry Kadashev exit2: 4414f5beed75SAl Viro path_put(&path); 44155d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 44165d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 44175d18f813SJeff Layton inode = NULL; 44185d18f813SJeff Layton goto retry; 44195d18f813SJeff Layton } 44200ee50b47SDmitry Kadashev exit1: 4421da2f1362SChristoph Hellwig putname(name); 44221da177e4SLinus Torvalds return error; 44231da177e4SLinus Torvalds 44241da177e4SLinus Torvalds slashes: 4425b18825a7SDavid Howells if (d_is_negative(dentry)) 4426b18825a7SDavid Howells error = -ENOENT; 442744b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4428b18825a7SDavid Howells error = -EISDIR; 4429b18825a7SDavid Howells else 4430b18825a7SDavid Howells error = -ENOTDIR; 44310ee50b47SDmitry Kadashev goto exit3; 44321da177e4SLinus Torvalds } 44331da177e4SLinus Torvalds 44342e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 44355590ff0dSUlrich Drepper { 44365590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 44375590ff0dSUlrich Drepper return -EINVAL; 44385590ff0dSUlrich Drepper 44395590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 4440e24ab0efSChristoph Hellwig return do_rmdir(dfd, getname(pathname)); 4441da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 44425590ff0dSUlrich Drepper } 44435590ff0dSUlrich Drepper 44443480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 44455590ff0dSUlrich Drepper { 4446da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 44475590ff0dSUlrich Drepper } 44485590ff0dSUlrich Drepper 44496521f891SChristian Brauner /** 44506521f891SChristian Brauner * vfs_symlink - create symlink 4451abf08576SChristian Brauner * @idmap: idmap of the mount the inode was found from 44526521f891SChristian Brauner * @dir: inode of @dentry 44536521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 44546521f891SChristian Brauner * @oldname: name of the file to link to 44556521f891SChristian Brauner * 44566521f891SChristian Brauner * Create a symlink. 44576521f891SChristian Brauner * 4458abf08576SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 4459abf08576SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 4460abf08576SChristian Brauner * care to map the inode according to @idmap before checking permissions. 44616521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 4462abf08576SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 44636521f891SChristian Brauner */ 4464abf08576SChristian Brauner int vfs_symlink(struct mnt_idmap *idmap, struct inode *dir, 44656521f891SChristian Brauner struct dentry *dentry, const char *oldname) 44661da177e4SLinus Torvalds { 44677a77db95SChristian Brauner int error; 44681da177e4SLinus Torvalds 44694609e1f1SChristian Brauner error = may_create(idmap, dir, dentry); 44701da177e4SLinus Torvalds if (error) 44711da177e4SLinus Torvalds return error; 44721da177e4SLinus Torvalds 4473acfa4380SAl Viro if (!dir->i_op->symlink) 44741da177e4SLinus Torvalds return -EPERM; 44751da177e4SLinus Torvalds 44761da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 44771da177e4SLinus Torvalds if (error) 44781da177e4SLinus Torvalds return error; 44791da177e4SLinus Torvalds 44807a77db95SChristian Brauner error = dir->i_op->symlink(idmap, dir, dentry, oldname); 4481a74574aaSStephen Smalley if (!error) 4482f38aa942SAmy Griffis fsnotify_create(dir, dentry); 44831da177e4SLinus Torvalds return error; 44841da177e4SLinus Torvalds } 44854d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 44861da177e4SLinus Torvalds 44877a8721f8SDmitry Kadashev int do_symlinkat(struct filename *from, int newdfd, struct filename *to) 44881da177e4SLinus Torvalds { 44892ad94ae6SAl Viro int error; 44906902d925SDave Hansen struct dentry *dentry; 4491dae6ad8fSAl Viro struct path path; 4492f46d3567SJeff Layton unsigned int lookup_flags = 0; 44931da177e4SLinus Torvalds 4494da2d0cedSDmitry Kadashev if (IS_ERR(from)) { 4495da2d0cedSDmitry Kadashev error = PTR_ERR(from); 4496da2d0cedSDmitry Kadashev goto out_putnames; 4497da2d0cedSDmitry Kadashev } 4498f46d3567SJeff Layton retry: 4499b4a4f213SStephen Brennan dentry = filename_create(newdfd, to, &path, lookup_flags); 45001da177e4SLinus Torvalds error = PTR_ERR(dentry); 45016902d925SDave Hansen if (IS_ERR(dentry)) 4502da2d0cedSDmitry Kadashev goto out_putnames; 45036902d925SDave Hansen 450491a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4505abf08576SChristian Brauner if (!error) 4506abf08576SChristian Brauner error = vfs_symlink(mnt_idmap(path.mnt), path.dentry->d_inode, 4507abf08576SChristian Brauner dentry, from->name); 4508921a1650SAl Viro done_path_create(&path, dentry); 4509f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4510f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4511f46d3567SJeff Layton goto retry; 4512f46d3567SJeff Layton } 4513da2d0cedSDmitry Kadashev out_putnames: 4514da2d0cedSDmitry Kadashev putname(to); 45151da177e4SLinus Torvalds putname(from); 45161da177e4SLinus Torvalds return error; 45171da177e4SLinus Torvalds } 45181da177e4SLinus Torvalds 4519b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4520b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4521b724e846SDominik Brodowski { 4522da2d0cedSDmitry Kadashev return do_symlinkat(getname(oldname), newdfd, getname(newname)); 4523b724e846SDominik Brodowski } 4524b724e846SDominik Brodowski 45253480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 45265590ff0dSUlrich Drepper { 4527da2d0cedSDmitry Kadashev return do_symlinkat(getname(oldname), AT_FDCWD, getname(newname)); 45285590ff0dSUlrich Drepper } 45295590ff0dSUlrich Drepper 4530146a8595SJ. Bruce Fields /** 4531146a8595SJ. Bruce Fields * vfs_link - create a new link 4532146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4533abf08576SChristian Brauner * @idmap: idmap of the mount 4534146a8595SJ. Bruce Fields * @dir: new parent 4535146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4536146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4537146a8595SJ. Bruce Fields * 4538146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4539146a8595SJ. Bruce Fields * 4540146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4541146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4542146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4543146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4544146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4545146a8595SJ. Bruce Fields * 4546146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4547146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4548146a8595SJ. Bruce Fields * to be NFS exported. 45496521f891SChristian Brauner * 4550abf08576SChristian Brauner * If the inode has been found through an idmapped mount the idmap of 4551abf08576SChristian Brauner * the vfsmount must be passed through @idmap. This function will then take 4552abf08576SChristian Brauner * care to map the inode according to @idmap before checking permissions. 45536521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 4554abf08576SChristian Brauner * raw inode simply passs @nop_mnt_idmap. 4555146a8595SJ. Bruce Fields */ 4556abf08576SChristian Brauner int vfs_link(struct dentry *old_dentry, struct mnt_idmap *idmap, 45576521f891SChristian Brauner struct inode *dir, struct dentry *new_dentry, 45586521f891SChristian Brauner struct inode **delegated_inode) 45591da177e4SLinus Torvalds { 45601da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 45618de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 45621da177e4SLinus Torvalds int error; 45631da177e4SLinus Torvalds 45641da177e4SLinus Torvalds if (!inode) 45651da177e4SLinus Torvalds return -ENOENT; 45661da177e4SLinus Torvalds 45674609e1f1SChristian Brauner error = may_create(idmap, dir, new_dentry); 45681da177e4SLinus Torvalds if (error) 45691da177e4SLinus Torvalds return error; 45701da177e4SLinus Torvalds 45711da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 45721da177e4SLinus Torvalds return -EXDEV; 45731da177e4SLinus Torvalds 45741da177e4SLinus Torvalds /* 45751da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 45761da177e4SLinus Torvalds */ 45771da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 45781da177e4SLinus Torvalds return -EPERM; 45790bd23d09SEric W. Biederman /* 45800bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 45810bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 45820bd23d09SEric W. Biederman * the vfs. 45830bd23d09SEric W. Biederman */ 45844609e1f1SChristian Brauner if (HAS_UNMAPPED_ID(idmap, inode)) 45850bd23d09SEric W. Biederman return -EPERM; 4586acfa4380SAl Viro if (!dir->i_op->link) 45871da177e4SLinus Torvalds return -EPERM; 45887e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 45891da177e4SLinus Torvalds return -EPERM; 45901da177e4SLinus Torvalds 45911da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 45921da177e4SLinus Torvalds if (error) 45931da177e4SLinus Torvalds return error; 45941da177e4SLinus Torvalds 45955955102cSAl Viro inode_lock(inode); 4596aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4597f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4598aae8a97dSAneesh Kumar K.V error = -ENOENT; 45998de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 46008de52778SAl Viro error = -EMLINK; 4601146a8595SJ. Bruce Fields else { 4602146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4603146a8595SJ. Bruce Fields if (!error) 46041da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4605146a8595SJ. Bruce Fields } 4606f4e0c30cSAl Viro 4607f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4608f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4609f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4610f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4611f4e0c30cSAl Viro } 46125955102cSAl Viro inode_unlock(inode); 4613e31e14ecSStephen Smalley if (!error) 46147e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 46151da177e4SLinus Torvalds return error; 46161da177e4SLinus Torvalds } 46174d359507SAl Viro EXPORT_SYMBOL(vfs_link); 46181da177e4SLinus Torvalds 46191da177e4SLinus Torvalds /* 46201da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 46211da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 46221da177e4SLinus Torvalds * newname. --KAB 46231da177e4SLinus Torvalds * 46241da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 46251da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 46261da177e4SLinus Torvalds * and other special files. --ADM 46271da177e4SLinus Torvalds */ 4628cf30da90SDmitry Kadashev int do_linkat(int olddfd, struct filename *old, int newdfd, 4629020250f3SDmitry Kadashev struct filename *new, int flags) 46301da177e4SLinus Torvalds { 4631abf08576SChristian Brauner struct mnt_idmap *idmap; 46321da177e4SLinus Torvalds struct dentry *new_dentry; 4633dae6ad8fSAl Viro struct path old_path, new_path; 4634146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 463511a7b371SAneesh Kumar K.V int how = 0; 46361da177e4SLinus Torvalds int error; 46371da177e4SLinus Torvalds 4638020250f3SDmitry Kadashev if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) { 4639020250f3SDmitry Kadashev error = -EINVAL; 4640020250f3SDmitry Kadashev goto out_putnames; 4641020250f3SDmitry Kadashev } 464211a7b371SAneesh Kumar K.V /* 4643f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4644f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4645f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 464611a7b371SAneesh Kumar K.V */ 4647020250f3SDmitry Kadashev if (flags & AT_EMPTY_PATH && !capable(CAP_DAC_READ_SEARCH)) { 4648020250f3SDmitry Kadashev error = -ENOENT; 4649020250f3SDmitry Kadashev goto out_putnames; 4650f0cc6ffbSLinus Torvalds } 4651c04030e1SUlrich Drepper 465211a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 465311a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4654442e31caSJeff Layton retry: 4655794ebceaSStephen Brennan error = filename_lookup(olddfd, old, how, &old_path, NULL); 46561da177e4SLinus Torvalds if (error) 4657020250f3SDmitry Kadashev goto out_putnames; 46582ad94ae6SAl Viro 4659b4a4f213SStephen Brennan new_dentry = filename_create(newdfd, new, &new_path, 4660442e31caSJeff Layton (how & LOOKUP_REVAL)); 46611da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 46626902d925SDave Hansen if (IS_ERR(new_dentry)) 4663020250f3SDmitry Kadashev goto out_putpath; 4664dae6ad8fSAl Viro 4665dae6ad8fSAl Viro error = -EXDEV; 4666dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4667dae6ad8fSAl Viro goto out_dput; 4668abf08576SChristian Brauner idmap = mnt_idmap(new_path.mnt); 46694609e1f1SChristian Brauner error = may_linkat(idmap, &old_path); 4670800179c9SKees Cook if (unlikely(error)) 4671800179c9SKees Cook goto out_dput; 4672dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4673be6d3e56SKentaro Takeda if (error) 4674a8104a9fSAl Viro goto out_dput; 4675abf08576SChristian Brauner error = vfs_link(old_path.dentry, idmap, new_path.dentry->d_inode, 46766521f891SChristian Brauner new_dentry, &delegated_inode); 467775c3f29dSDave Hansen out_dput: 4678921a1650SAl Viro done_path_create(&new_path, new_dentry); 4679146a8595SJ. Bruce Fields if (delegated_inode) { 4680146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4681d22e6338SOleg Drokin if (!error) { 4682d22e6338SOleg Drokin path_put(&old_path); 4683146a8595SJ. Bruce Fields goto retry; 4684146a8595SJ. Bruce Fields } 4685d22e6338SOleg Drokin } 4686442e31caSJeff Layton if (retry_estale(error, how)) { 4687d22e6338SOleg Drokin path_put(&old_path); 4688442e31caSJeff Layton how |= LOOKUP_REVAL; 4689442e31caSJeff Layton goto retry; 4690442e31caSJeff Layton } 4691020250f3SDmitry Kadashev out_putpath: 46922d8f3038SAl Viro path_put(&old_path); 4693020250f3SDmitry Kadashev out_putnames: 4694020250f3SDmitry Kadashev putname(old); 4695020250f3SDmitry Kadashev putname(new); 46961da177e4SLinus Torvalds 46971da177e4SLinus Torvalds return error; 46981da177e4SLinus Torvalds } 46991da177e4SLinus Torvalds 470046ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 470146ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 470246ea89ebSDominik Brodowski { 4703020250f3SDmitry Kadashev return do_linkat(olddfd, getname_uflags(oldname, flags), 4704020250f3SDmitry Kadashev newdfd, getname(newname), flags); 470546ea89ebSDominik Brodowski } 470646ea89ebSDominik Brodowski 47073480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 47085590ff0dSUlrich Drepper { 4709020250f3SDmitry Kadashev return do_linkat(AT_FDCWD, getname(oldname), AT_FDCWD, getname(newname), 0); 47105590ff0dSUlrich Drepper } 47115590ff0dSUlrich Drepper 4712bc27027aSMiklos Szeredi /** 4713bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 47142111c3c0SRandy Dunlap * @rd: pointer to &struct renamedata info 4715bc27027aSMiklos Szeredi * 4716bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4717bc27027aSMiklos Szeredi * 4718bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4719bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4720bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4721bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4722bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4723bc27027aSMiklos Szeredi * so. 4724bc27027aSMiklos Szeredi * 4725bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4726bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4727bc27027aSMiklos Szeredi * to be NFS exported. 4728bc27027aSMiklos Szeredi * 47291da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 47301da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 47311da177e4SLinus Torvalds * Problems: 47320117d427SMauro Carvalho Chehab * 4733d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 47341da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 47351da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4736a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 47371da177e4SLinus Torvalds * story. 47386cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 473928eceedaSJan Kara * and source. 47401b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 47411da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 47421da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4743a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 47441da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 47451da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 47461da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4747a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 47481da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 47491da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 47501da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4751e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 47521b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 47531da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4754c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 47551da177e4SLinus Torvalds * locking]. 47561da177e4SLinus Torvalds */ 47579fe61450SChristian Brauner int vfs_rename(struct renamedata *rd) 47581da177e4SLinus Torvalds { 47591da177e4SLinus Torvalds int error; 47609fe61450SChristian Brauner struct inode *old_dir = rd->old_dir, *new_dir = rd->new_dir; 47619fe61450SChristian Brauner struct dentry *old_dentry = rd->old_dentry; 47629fe61450SChristian Brauner struct dentry *new_dentry = rd->new_dentry; 47639fe61450SChristian Brauner struct inode **delegated_inode = rd->delegated_inode; 47649fe61450SChristian Brauner unsigned int flags = rd->flags; 4765bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4766bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4767bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4768da1ce067SMiklos Szeredi bool new_is_dir = false; 4769da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 477049d31c2fSAl Viro struct name_snapshot old_name; 47711da177e4SLinus Torvalds 47728d3e2936SMiklos Szeredi if (source == target) 47731da177e4SLinus Torvalds return 0; 47741da177e4SLinus Torvalds 47754609e1f1SChristian Brauner error = may_delete(rd->old_mnt_idmap, old_dir, old_dentry, is_dir); 47761da177e4SLinus Torvalds if (error) 47771da177e4SLinus Torvalds return error; 47781da177e4SLinus Torvalds 4779da1ce067SMiklos Szeredi if (!target) { 47804609e1f1SChristian Brauner error = may_create(rd->new_mnt_idmap, new_dir, new_dentry); 4781da1ce067SMiklos Szeredi } else { 4782da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4783da1ce067SMiklos Szeredi 4784da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 47854609e1f1SChristian Brauner error = may_delete(rd->new_mnt_idmap, new_dir, 47866521f891SChristian Brauner new_dentry, is_dir); 4787da1ce067SMiklos Szeredi else 47884609e1f1SChristian Brauner error = may_delete(rd->new_mnt_idmap, new_dir, 47896521f891SChristian Brauner new_dentry, new_is_dir); 4790da1ce067SMiklos Szeredi } 47911da177e4SLinus Torvalds if (error) 47921da177e4SLinus Torvalds return error; 47931da177e4SLinus Torvalds 47942773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 47951da177e4SLinus Torvalds return -EPERM; 47961da177e4SLinus Torvalds 4797bc27027aSMiklos Szeredi /* 4798bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4799bc27027aSMiklos Szeredi * we'll need to flip '..'. 4800bc27027aSMiklos Szeredi */ 4801da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4802da1ce067SMiklos Szeredi if (is_dir) { 48034609e1f1SChristian Brauner error = inode_permission(rd->old_mnt_idmap, source, 480447291baaSChristian Brauner MAY_WRITE); 4805bc27027aSMiklos Szeredi if (error) 4806bc27027aSMiklos Szeredi return error; 4807bc27027aSMiklos Szeredi } 4808da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 48094609e1f1SChristian Brauner error = inode_permission(rd->new_mnt_idmap, target, 481047291baaSChristian Brauner MAY_WRITE); 4811da1ce067SMiklos Szeredi if (error) 4812da1ce067SMiklos Szeredi return error; 4813da1ce067SMiklos Szeredi } 4814da1ce067SMiklos Szeredi } 48150eeca283SRobert Love 48160b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 48170b3974ebSMiklos Szeredi flags); 4818bc27027aSMiklos Szeredi if (error) 4819bc27027aSMiklos Szeredi return error; 4820bc27027aSMiklos Szeredi 482149d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4822bc27027aSMiklos Szeredi dget(new_dentry); 482328eceedaSJan Kara /* 482428eceedaSJan Kara * Lock all moved children. Moved directories may need to change parent 482528eceedaSJan Kara * pointer so they need the lock to prevent against concurrent 482628eceedaSJan Kara * directory changes moving parent pointer. For regular files we've 482728eceedaSJan Kara * historically always done this. The lockdep locking subclasses are 482828eceedaSJan Kara * somewhat arbitrary but RENAME_EXCHANGE in particular can swap 482928eceedaSJan Kara * regular files and directories so it's difficult to tell which 483028eceedaSJan Kara * subclasses to use. 483128eceedaSJan Kara */ 483228eceedaSJan Kara lock_two_inodes(source, target, I_MUTEX_NORMAL, I_MUTEX_NONDIR2); 4833bc27027aSMiklos Szeredi 483451cc3a66SHugh Dickins error = -EPERM; 483551cc3a66SHugh Dickins if (IS_SWAPFILE(source) || (target && IS_SWAPFILE(target))) 483651cc3a66SHugh Dickins goto out; 483751cc3a66SHugh Dickins 4838bc27027aSMiklos Szeredi error = -EBUSY; 48397af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4840bc27027aSMiklos Szeredi goto out; 4841bc27027aSMiklos Szeredi 4842da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4843bc27027aSMiklos Szeredi error = -EMLINK; 4844da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4845bc27027aSMiklos Szeredi goto out; 4846da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4847da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4848da1ce067SMiklos Szeredi goto out; 4849da1ce067SMiklos Szeredi } 4850da1ce067SMiklos Szeredi if (!is_dir) { 4851bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4852bc27027aSMiklos Szeredi if (error) 4853bc27027aSMiklos Szeredi goto out; 4854da1ce067SMiklos Szeredi } 4855da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4856bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4857bc27027aSMiklos Szeredi if (error) 4858bc27027aSMiklos Szeredi goto out; 4859bc27027aSMiklos Szeredi } 4860e18275aeSChristian Brauner error = old_dir->i_op->rename(rd->new_mnt_idmap, old_dir, old_dentry, 4861520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4862bc27027aSMiklos Szeredi if (error) 4863bc27027aSMiklos Szeredi goto out; 4864bc27027aSMiklos Szeredi 4865da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 48668767712fSAl Viro if (is_dir) { 48678767712fSAl Viro shrink_dcache_parent(new_dentry); 4868bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 48698767712fSAl Viro } 4870bc27027aSMiklos Szeredi dont_mount(new_dentry); 48718ed936b5SEric W. Biederman detach_mounts(new_dentry); 4872bc27027aSMiklos Szeredi } 4873da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4874da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4875bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4876da1ce067SMiklos Szeredi else 4877da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4878da1ce067SMiklos Szeredi } 4879bc27027aSMiklos Szeredi out: 488028eceedaSJan Kara inode_unlock(source); 488128eceedaSJan Kara if (target) 48825955102cSAl Viro inode_unlock(target); 4883bc27027aSMiklos Szeredi dput(new_dentry); 4884da1ce067SMiklos Szeredi if (!error) { 4885f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4886da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4887da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4888f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4889da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4890da1ce067SMiklos Szeredi } 4891da1ce067SMiklos Szeredi } 489249d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 48930eeca283SRobert Love 48941da177e4SLinus Torvalds return error; 48951da177e4SLinus Torvalds } 48964d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 48971da177e4SLinus Torvalds 4898e886663cSJens Axboe int do_renameat2(int olddfd, struct filename *from, int newdfd, 4899e886663cSJens Axboe struct filename *to, unsigned int flags) 49001da177e4SLinus Torvalds { 49019fe61450SChristian Brauner struct renamedata rd; 49021da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 49031da177e4SLinus Torvalds struct dentry *trap; 4904f5beed75SAl Viro struct path old_path, new_path; 4905f5beed75SAl Viro struct qstr old_last, new_last; 4906f5beed75SAl Viro int old_type, new_type; 49078e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 4908f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4909c6a94284SJeff Layton bool should_retry = false; 4910e886663cSJens Axboe int error = -EINVAL; 4911520c8b16SMiklos Szeredi 49120d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 49130ee50b47SDmitry Kadashev goto put_names; 4914da1ce067SMiklos Szeredi 49150d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 49160d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 49170ee50b47SDmitry Kadashev goto put_names; 4918520c8b16SMiklos Szeredi 4919f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4920f5beed75SAl Viro target_flags = 0; 4921f5beed75SAl Viro 4922c6a94284SJeff Layton retry: 4923c5f563f9SAl Viro error = filename_parentat(olddfd, from, lookup_flags, &old_path, 4924e886663cSJens Axboe &old_last, &old_type); 49250ee50b47SDmitry Kadashev if (error) 49260ee50b47SDmitry Kadashev goto put_names; 49271da177e4SLinus Torvalds 4928c5f563f9SAl Viro error = filename_parentat(newdfd, to, lookup_flags, &new_path, &new_last, 4929e886663cSJens Axboe &new_type); 49300ee50b47SDmitry Kadashev if (error) 49311da177e4SLinus Torvalds goto exit1; 49321da177e4SLinus Torvalds 49331da177e4SLinus Torvalds error = -EXDEV; 4934f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 49351da177e4SLinus Torvalds goto exit2; 49361da177e4SLinus Torvalds 49371da177e4SLinus Torvalds error = -EBUSY; 4938f5beed75SAl Viro if (old_type != LAST_NORM) 49391da177e4SLinus Torvalds goto exit2; 49401da177e4SLinus Torvalds 49410a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 49420a7c3937SMiklos Szeredi error = -EEXIST; 4943f5beed75SAl Viro if (new_type != LAST_NORM) 49441da177e4SLinus Torvalds goto exit2; 49451da177e4SLinus Torvalds 4946f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4947c30dabfeSJan Kara if (error) 4948c30dabfeSJan Kara goto exit2; 4949c30dabfeSJan Kara 49508e6d782cSJ. Bruce Fields retry_deleg: 4951f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 49521da177e4SLinus Torvalds 495374d7970fSNamjae Jeon old_dentry = lookup_one_qstr_excl(&old_last, old_path.dentry, 495474d7970fSNamjae Jeon lookup_flags); 49551da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 49561da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 49571da177e4SLinus Torvalds goto exit3; 49581da177e4SLinus Torvalds /* source must exist */ 49591da177e4SLinus Torvalds error = -ENOENT; 4960b18825a7SDavid Howells if (d_is_negative(old_dentry)) 49611da177e4SLinus Torvalds goto exit4; 496274d7970fSNamjae Jeon new_dentry = lookup_one_qstr_excl(&new_last, new_path.dentry, 496374d7970fSNamjae Jeon lookup_flags | target_flags); 49641da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 49651da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 49661da177e4SLinus Torvalds goto exit4; 49670a7c3937SMiklos Szeredi error = -EEXIST; 49680a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 49690a7c3937SMiklos Szeredi goto exit5; 4970da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4971da1ce067SMiklos Szeredi error = -ENOENT; 4972da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4973da1ce067SMiklos Szeredi goto exit5; 4974da1ce067SMiklos Szeredi 4975da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4976da1ce067SMiklos Szeredi error = -ENOTDIR; 4977f5beed75SAl Viro if (new_last.name[new_last.len]) 4978da1ce067SMiklos Szeredi goto exit5; 4979da1ce067SMiklos Szeredi } 4980da1ce067SMiklos Szeredi } 49810a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 49820a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 49830a7c3937SMiklos Szeredi error = -ENOTDIR; 4984f5beed75SAl Viro if (old_last.name[old_last.len]) 49850a7c3937SMiklos Szeredi goto exit5; 4986f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 49870a7c3937SMiklos Szeredi goto exit5; 49880a7c3937SMiklos Szeredi } 49890a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 49900a7c3937SMiklos Szeredi error = -EINVAL; 49910a7c3937SMiklos Szeredi if (old_dentry == trap) 49920a7c3937SMiklos Szeredi goto exit5; 49931da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4994da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 49951da177e4SLinus Torvalds error = -ENOTEMPTY; 49961da177e4SLinus Torvalds if (new_dentry == trap) 49971da177e4SLinus Torvalds goto exit5; 49981da177e4SLinus Torvalds 4999f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 5000f5beed75SAl Viro &new_path, new_dentry, flags); 5001be6d3e56SKentaro Takeda if (error) 5002c30dabfeSJan Kara goto exit5; 50039fe61450SChristian Brauner 50049fe61450SChristian Brauner rd.old_dir = old_path.dentry->d_inode; 50059fe61450SChristian Brauner rd.old_dentry = old_dentry; 5006abf08576SChristian Brauner rd.old_mnt_idmap = mnt_idmap(old_path.mnt); 50079fe61450SChristian Brauner rd.new_dir = new_path.dentry->d_inode; 50089fe61450SChristian Brauner rd.new_dentry = new_dentry; 5009abf08576SChristian Brauner rd.new_mnt_idmap = mnt_idmap(new_path.mnt); 50109fe61450SChristian Brauner rd.delegated_inode = &delegated_inode; 50119fe61450SChristian Brauner rd.flags = flags; 50129fe61450SChristian Brauner error = vfs_rename(&rd); 50131da177e4SLinus Torvalds exit5: 50141da177e4SLinus Torvalds dput(new_dentry); 50151da177e4SLinus Torvalds exit4: 50161da177e4SLinus Torvalds dput(old_dentry); 50171da177e4SLinus Torvalds exit3: 5018f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 50198e6d782cSJ. Bruce Fields if (delegated_inode) { 50208e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 50218e6d782cSJ. Bruce Fields if (!error) 50228e6d782cSJ. Bruce Fields goto retry_deleg; 50238e6d782cSJ. Bruce Fields } 5024f5beed75SAl Viro mnt_drop_write(old_path.mnt); 50251da177e4SLinus Torvalds exit2: 5026c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 5027c6a94284SJeff Layton should_retry = true; 5028f5beed75SAl Viro path_put(&new_path); 50291da177e4SLinus Torvalds exit1: 5030f5beed75SAl Viro path_put(&old_path); 5031c6a94284SJeff Layton if (should_retry) { 5032c6a94284SJeff Layton should_retry = false; 5033c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 5034c6a94284SJeff Layton goto retry; 5035c6a94284SJeff Layton } 50360ee50b47SDmitry Kadashev put_names: 5037e886663cSJens Axboe putname(from); 5038e886663cSJens Axboe putname(to); 50391da177e4SLinus Torvalds return error; 50401da177e4SLinus Torvalds } 50411da177e4SLinus Torvalds 5042ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 5043ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 5044ee81feb6SDominik Brodowski { 5045e886663cSJens Axboe return do_renameat2(olddfd, getname(oldname), newdfd, getname(newname), 5046e886663cSJens Axboe flags); 5047ee81feb6SDominik Brodowski } 5048ee81feb6SDominik Brodowski 5049520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 5050520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 5051520c8b16SMiklos Szeredi { 5052e886663cSJens Axboe return do_renameat2(olddfd, getname(oldname), newdfd, getname(newname), 5053e886663cSJens Axboe 0); 5054520c8b16SMiklos Szeredi } 5055520c8b16SMiklos Szeredi 5056a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 50575590ff0dSUlrich Drepper { 5058e886663cSJens Axboe return do_renameat2(AT_FDCWD, getname(oldname), AT_FDCWD, 5059e886663cSJens Axboe getname(newname), 0); 50605590ff0dSUlrich Drepper } 50615590ff0dSUlrich Drepper 50625d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 50631da177e4SLinus Torvalds { 50645d826c84SAl Viro int len = PTR_ERR(link); 50651da177e4SLinus Torvalds if (IS_ERR(link)) 50661da177e4SLinus Torvalds goto out; 50671da177e4SLinus Torvalds 50681da177e4SLinus Torvalds len = strlen(link); 50691da177e4SLinus Torvalds if (len > (unsigned) buflen) 50701da177e4SLinus Torvalds len = buflen; 50711da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 50721da177e4SLinus Torvalds len = -EFAULT; 50731da177e4SLinus Torvalds out: 50741da177e4SLinus Torvalds return len; 50751da177e4SLinus Torvalds } 50761da177e4SLinus Torvalds 5077d60874cdSMiklos Szeredi /** 5078fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 5079fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 5080fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 5081fd4a0edfSMiklos Szeredi * @buflen: size of buffer 5082fd4a0edfSMiklos Szeredi * 5083fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 5084fd4a0edfSMiklos Szeredi * 5085fd4a0edfSMiklos Szeredi * Does not call security hook. 5086fd4a0edfSMiklos Szeredi */ 5087fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 5088fd4a0edfSMiklos Szeredi { 5089fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 5090f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 5091f2df5da6SAl Viro const char *link; 5092f2df5da6SAl Viro int res; 5093fd4a0edfSMiklos Szeredi 509476fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 509576fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 509676fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 509776fca90eSMiklos Szeredi 509876fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 5099fd4a0edfSMiklos Szeredi return -EINVAL; 5100fd4a0edfSMiklos Szeredi 510176fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 510276fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 510376fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 510476fca90eSMiklos Szeredi } 510576fca90eSMiklos Szeredi 51064c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 5107f2df5da6SAl Viro if (!link) { 5108f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 5109f2df5da6SAl Viro if (IS_ERR(link)) 5110f2df5da6SAl Viro return PTR_ERR(link); 5111f2df5da6SAl Viro } 5112f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 5113f2df5da6SAl Viro do_delayed_call(&done); 5114f2df5da6SAl Viro return res; 5115fd4a0edfSMiklos Szeredi } 5116fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 51171da177e4SLinus Torvalds 5118d60874cdSMiklos Szeredi /** 5119d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 5120d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 5121d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 5122d60874cdSMiklos Szeredi * 5123d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 5124d60874cdSMiklos Szeredi * 5125d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 5126d60874cdSMiklos Szeredi * 5127d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 5128d60874cdSMiklos Szeredi */ 5129d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 5130d60874cdSMiklos Szeredi { 5131d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 5132d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 5133d60874cdSMiklos Szeredi 5134d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 5135d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 5136d60874cdSMiklos Szeredi if (!res) 5137d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 5138d60874cdSMiklos Szeredi } 5139d60874cdSMiklos Szeredi return res; 5140d60874cdSMiklos Szeredi } 5141d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 5142d60874cdSMiklos Szeredi 51431da177e4SLinus Torvalds /* get the link contents into pagecache */ 51446b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 5145fceef393SAl Viro struct delayed_call *callback) 51461da177e4SLinus Torvalds { 5147ebd09abbSDuane Griffin char *kaddr; 51481da177e4SLinus Torvalds struct page *page; 51496b255391SAl Viro struct address_space *mapping = inode->i_mapping; 51506b255391SAl Viro 5151d3883d4fSAl Viro if (!dentry) { 5152d3883d4fSAl Viro page = find_get_page(mapping, 0); 5153d3883d4fSAl Viro if (!page) 51546b255391SAl Viro return ERR_PTR(-ECHILD); 5155d3883d4fSAl Viro if (!PageUptodate(page)) { 5156d3883d4fSAl Viro put_page(page); 5157d3883d4fSAl Viro return ERR_PTR(-ECHILD); 5158d3883d4fSAl Viro } 5159d3883d4fSAl Viro } else { 5160090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 51611da177e4SLinus Torvalds if (IS_ERR(page)) 51626fe6900eSNick Piggin return (char*)page; 5163d3883d4fSAl Viro } 5164fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 516521fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 516621fc61c7SAl Viro kaddr = page_address(page); 51676b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 5168ebd09abbSDuane Griffin return kaddr; 51691da177e4SLinus Torvalds } 51701da177e4SLinus Torvalds 51716b255391SAl Viro EXPORT_SYMBOL(page_get_link); 51721da177e4SLinus Torvalds 5173fceef393SAl Viro void page_put_link(void *arg) 51741da177e4SLinus Torvalds { 5175fceef393SAl Viro put_page(arg); 51761da177e4SLinus Torvalds } 51774d359507SAl Viro EXPORT_SYMBOL(page_put_link); 51781da177e4SLinus Torvalds 5179aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 5180aa80deabSAl Viro { 5181fceef393SAl Viro DEFINE_DELAYED_CALL(done); 51826b255391SAl Viro int res = readlink_copy(buffer, buflen, 51836b255391SAl Viro page_get_link(dentry, d_inode(dentry), 5184fceef393SAl Viro &done)); 5185fceef393SAl Viro do_delayed_call(&done); 5186aa80deabSAl Viro return res; 5187aa80deabSAl Viro } 5188aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 5189aa80deabSAl Viro 519056f5746cSMatthew Wilcox (Oracle) int page_symlink(struct inode *inode, const char *symname, int len) 51911da177e4SLinus Torvalds { 51921da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 519327a77913SMatthew Wilcox (Oracle) const struct address_space_operations *aops = mapping->a_ops; 519456f5746cSMatthew Wilcox (Oracle) bool nofs = !mapping_gfp_constraint(mapping, __GFP_FS); 51950adb25d2SKirill Korotaev struct page *page; 51961468c6f4SAlexander Potapenko void *fsdata = NULL; 5197beb497abSDmitriy Monakhov int err; 51982d878178SMatthew Wilcox (Oracle) unsigned int flags; 51991da177e4SLinus Torvalds 52007e53cac4SNeilBrown retry: 52012d878178SMatthew Wilcox (Oracle) if (nofs) 52022d878178SMatthew Wilcox (Oracle) flags = memalloc_nofs_save(); 520327a77913SMatthew Wilcox (Oracle) err = aops->write_begin(NULL, mapping, 0, len-1, &page, &fsdata); 52042d878178SMatthew Wilcox (Oracle) if (nofs) 52052d878178SMatthew Wilcox (Oracle) memalloc_nofs_restore(flags); 52061da177e4SLinus Torvalds if (err) 5207afddba49SNick Piggin goto fail; 5208afddba49SNick Piggin 520921fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 5210afddba49SNick Piggin 521127a77913SMatthew Wilcox (Oracle) err = aops->write_end(NULL, mapping, 0, len-1, len-1, 5212afddba49SNick Piggin page, fsdata); 52131da177e4SLinus Torvalds if (err < 0) 52141da177e4SLinus Torvalds goto fail; 5215afddba49SNick Piggin if (err < len-1) 5216afddba49SNick Piggin goto retry; 5217afddba49SNick Piggin 52181da177e4SLinus Torvalds mark_inode_dirty(inode); 52191da177e4SLinus Torvalds return 0; 52201da177e4SLinus Torvalds fail: 52211da177e4SLinus Torvalds return err; 52221da177e4SLinus Torvalds } 52234d359507SAl Viro EXPORT_SYMBOL(page_symlink); 52240adb25d2SKirill Korotaev 522592e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 52266b255391SAl Viro .get_link = page_get_link, 52271da177e4SLinus Torvalds }; 52281da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 5229