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> 231da177e4SLinus Torvalds #include <linux/namei.h> 241da177e4SLinus Torvalds #include <linux/pagemap.h> 252d878178SMatthew Wilcox (Oracle) #include <linux/sched/mm.h> 260eeca283SRobert Love #include <linux/fsnotify.h> 271da177e4SLinus Torvalds #include <linux/personality.h> 281da177e4SLinus Torvalds #include <linux/security.h> 296146f0d5SMimi Zohar #include <linux/ima.h> 301da177e4SLinus Torvalds #include <linux/syscalls.h> 311da177e4SLinus Torvalds #include <linux/mount.h> 321da177e4SLinus Torvalds #include <linux/audit.h> 3316f7e0feSRandy Dunlap #include <linux/capability.h> 34834f2a4aSTrond Myklebust #include <linux/file.h> 355590ff0dSUlrich Drepper #include <linux/fcntl.h> 3608ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 375ad4e53bSAl Viro #include <linux/fs_struct.h> 38e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3999d263d4SLinus Torvalds #include <linux/hash.h> 402a18da7aSGeorge Spelvin #include <linux/bitops.h> 41aeaa4a79SEric W. Biederman #include <linux/init_task.h> 427c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 431da177e4SLinus Torvalds 44e81e3f4dSEric Paris #include "internal.h" 45c7105365SAl Viro #include "mount.h" 46e81e3f4dSEric Paris 471da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 481da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 491da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 501da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 511da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 521da177e4SLinus Torvalds * 531da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 541da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 551da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 561da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 571da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 581da177e4SLinus Torvalds * the special cases of the former code. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 611da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 621da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 631da177e4SLinus Torvalds * 641da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 651da177e4SLinus Torvalds * resolution to correspond with current state of the code. 661da177e4SLinus Torvalds * 671da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 681da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 691da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 701da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 711da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 721da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 731da177e4SLinus Torvalds */ 741da177e4SLinus Torvalds 751da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 761da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 771da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 781da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 791da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 801da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8125985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 821da177e4SLinus Torvalds * 831da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 841da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 851da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 861da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 871da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 881da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 891da177e4SLinus Torvalds * and in the old Linux semantics. 901da177e4SLinus Torvalds */ 911da177e4SLinus Torvalds 921da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 931da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 941da177e4SLinus Torvalds * 951da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 961da177e4SLinus Torvalds */ 971da177e4SLinus Torvalds 981da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 991da177e4SLinus Torvalds * inside the path - always follow. 1001da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1011da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1021da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1031da177e4SLinus Torvalds * otherwise - don't follow. 1041da177e4SLinus Torvalds * (applied in that order). 1051da177e4SLinus Torvalds * 1061da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1071da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1081da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1091da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1101da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1111da177e4SLinus Torvalds */ 1121da177e4SLinus Torvalds /* 1131da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 114a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1151da177e4SLinus Torvalds * any extra contention... 1161da177e4SLinus Torvalds */ 1171da177e4SLinus Torvalds 1181da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1191da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1201da177e4SLinus Torvalds * kernel data space before using them.. 1211da177e4SLinus Torvalds * 1221da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1231da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1241da177e4SLinus Torvalds */ 1257950e385SJeff Layton 126fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12791a27b2aSJeff Layton 12851f39a1fSDavid Drysdale struct filename * 12991a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 13091a27b2aSJeff Layton { 13194b5d262SAl Viro struct filename *result; 1327950e385SJeff Layton char *kname; 13394b5d262SAl Viro int len; 1341da177e4SLinus Torvalds 1357ac86265SJeff Layton result = audit_reusename(filename); 1367ac86265SJeff Layton if (result) 1377ac86265SJeff Layton return result; 1387ac86265SJeff Layton 1397950e385SJeff Layton result = __getname(); 1403f9f0aa6SLinus Torvalds if (unlikely(!result)) 1414043cde8SEric Paris return ERR_PTR(-ENOMEM); 1421da177e4SLinus Torvalds 1437950e385SJeff Layton /* 1447950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1457950e385SJeff Layton * allocation 1467950e385SJeff Layton */ 147fd2f7cb5SAl Viro kname = (char *)result->iname; 14891a27b2aSJeff Layton result->name = kname; 1497950e385SJeff Layton 15094b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15191a27b2aSJeff Layton if (unlikely(len < 0)) { 15294b5d262SAl Viro __putname(result); 15394b5d262SAl Viro return ERR_PTR(len); 15491a27b2aSJeff Layton } 1553f9f0aa6SLinus Torvalds 1567950e385SJeff Layton /* 1577950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1587950e385SJeff Layton * separate struct filename so we can dedicate the entire 1597950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1607950e385SJeff Layton * userland. 1617950e385SJeff Layton */ 16294b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 163fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1647950e385SJeff Layton kname = (char *)result; 1657950e385SJeff Layton 166fd2f7cb5SAl Viro /* 167fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 168fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 169fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 170fd2f7cb5SAl Viro */ 171fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17294b5d262SAl Viro if (unlikely(!result)) { 17394b5d262SAl Viro __putname(kname); 17494b5d262SAl Viro return ERR_PTR(-ENOMEM); 1757950e385SJeff Layton } 1767950e385SJeff Layton result->name = kname; 17794b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17894b5d262SAl Viro if (unlikely(len < 0)) { 17994b5d262SAl Viro __putname(kname); 18094b5d262SAl Viro kfree(result); 18194b5d262SAl Viro return ERR_PTR(len); 18294b5d262SAl Viro } 18394b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18494b5d262SAl Viro __putname(kname); 18594b5d262SAl Viro kfree(result); 18694b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18794b5d262SAl Viro } 1887950e385SJeff Layton } 1897950e385SJeff Layton 19094b5d262SAl Viro result->refcnt = 1; 1913f9f0aa6SLinus Torvalds /* The empty path is special. */ 1923f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1933f9f0aa6SLinus Torvalds if (empty) 1941fa1e7f6SAndy Whitcroft *empty = 1; 19594b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19694b5d262SAl Viro putname(result); 19794b5d262SAl Viro return ERR_PTR(-ENOENT); 1981da177e4SLinus Torvalds } 19994b5d262SAl Viro } 2007950e385SJeff Layton 2017950e385SJeff Layton result->uptr = filename; 202c4ad8f98SLinus Torvalds result->aname = NULL; 2031da177e4SLinus Torvalds audit_getname(result); 2041da177e4SLinus Torvalds return result; 2053f9f0aa6SLinus Torvalds } 2063f9f0aa6SLinus Torvalds 20791a27b2aSJeff Layton struct filename * 2088228e2c3SDmitry Kadashev getname_uflags(const char __user *filename, int uflags) 2098228e2c3SDmitry Kadashev { 2108228e2c3SDmitry Kadashev int flags = (uflags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0; 2118228e2c3SDmitry Kadashev 2128228e2c3SDmitry Kadashev return getname_flags(filename, flags, NULL); 2138228e2c3SDmitry Kadashev } 2148228e2c3SDmitry Kadashev 2158228e2c3SDmitry Kadashev struct filename * 21691a27b2aSJeff Layton getname(const char __user * filename) 217f52e0c11SAl Viro { 218f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 219f52e0c11SAl Viro } 220f52e0c11SAl Viro 221c4ad8f98SLinus Torvalds struct filename * 222c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 223c4ad8f98SLinus Torvalds { 224c4ad8f98SLinus Torvalds struct filename *result; 22508518549SPaul Moore int len = strlen(filename) + 1; 226c4ad8f98SLinus Torvalds 227c4ad8f98SLinus Torvalds result = __getname(); 228c4ad8f98SLinus Torvalds if (unlikely(!result)) 229c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 230c4ad8f98SLinus Torvalds 23108518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 232fd2f7cb5SAl Viro result->name = (char *)result->iname; 23308518549SPaul Moore } else if (len <= PATH_MAX) { 23430ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 23508518549SPaul Moore struct filename *tmp; 23608518549SPaul Moore 23730ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 23808518549SPaul Moore if (unlikely(!tmp)) { 23908518549SPaul Moore __putname(result); 24008518549SPaul Moore return ERR_PTR(-ENOMEM); 24108518549SPaul Moore } 24208518549SPaul Moore tmp->name = (char *)result; 24308518549SPaul Moore result = tmp; 24408518549SPaul Moore } else { 24508518549SPaul Moore __putname(result); 24608518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 24708518549SPaul Moore } 24808518549SPaul Moore memcpy((char *)result->name, filename, len); 249c4ad8f98SLinus Torvalds result->uptr = NULL; 250c4ad8f98SLinus Torvalds result->aname = NULL; 25155422d0bSPaul Moore result->refcnt = 1; 252fd3522fdSPaul Moore audit_getname(result); 253c4ad8f98SLinus Torvalds 254c4ad8f98SLinus Torvalds return result; 255c4ad8f98SLinus Torvalds } 256c4ad8f98SLinus Torvalds 25791a27b2aSJeff Layton void putname(struct filename *name) 2581da177e4SLinus Torvalds { 259ea47ab11SAl Viro if (IS_ERR(name)) 26091ef658fSDmitry Kadashev return; 26191ef658fSDmitry Kadashev 26255422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 26355422d0bSPaul Moore 26455422d0bSPaul Moore if (--name->refcnt > 0) 26555422d0bSPaul Moore return; 26655422d0bSPaul Moore 267fd2f7cb5SAl Viro if (name->name != name->iname) { 26855422d0bSPaul Moore __putname(name->name); 26955422d0bSPaul Moore kfree(name); 27055422d0bSPaul Moore } else 27155422d0bSPaul Moore __putname(name); 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds 27447291baaSChristian Brauner /** 27547291baaSChristian Brauner * check_acl - perform ACL permission checking 27647291baaSChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 27747291baaSChristian Brauner * @inode: inode to check permissions on 27847291baaSChristian Brauner * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...) 27947291baaSChristian Brauner * 28047291baaSChristian Brauner * This function performs the ACL permission checking. Since this function 28147291baaSChristian Brauner * retrieve POSIX acls it needs to know whether it is called from a blocking or 28247291baaSChristian Brauner * non-blocking context and thus cares about the MAY_NOT_BLOCK bit. 28347291baaSChristian Brauner * 28447291baaSChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 28547291baaSChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 28647291baaSChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 28747291baaSChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 28847291baaSChristian Brauner * raw inode simply passs init_user_ns. 28947291baaSChristian Brauner */ 29047291baaSChristian Brauner static int check_acl(struct user_namespace *mnt_userns, 29147291baaSChristian Brauner struct inode *inode, int mask) 292e77819e5SLinus Torvalds { 29384635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 294e77819e5SLinus Torvalds struct posix_acl *acl; 295e77819e5SLinus Torvalds 296e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2973567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2983567866bSAl Viro if (!acl) 299e77819e5SLinus Torvalds return -EAGAIN; 3003567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 301b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 302e77819e5SLinus Torvalds return -ECHILD; 30347291baaSChristian Brauner return posix_acl_permission(mnt_userns, inode, acl, mask); 304e77819e5SLinus Torvalds } 305e77819e5SLinus Torvalds 3062982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 3074e34e719SChristoph Hellwig if (IS_ERR(acl)) 3084e34e719SChristoph Hellwig return PTR_ERR(acl); 309e77819e5SLinus Torvalds if (acl) { 31047291baaSChristian Brauner int error = posix_acl_permission(mnt_userns, inode, acl, mask); 311e77819e5SLinus Torvalds posix_acl_release(acl); 312e77819e5SLinus Torvalds return error; 313e77819e5SLinus Torvalds } 31484635d68SLinus Torvalds #endif 315e77819e5SLinus Torvalds 316e77819e5SLinus Torvalds return -EAGAIN; 317e77819e5SLinus Torvalds } 318e77819e5SLinus Torvalds 31947291baaSChristian Brauner /** 32047291baaSChristian Brauner * acl_permission_check - perform basic UNIX permission checking 32147291baaSChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 32247291baaSChristian Brauner * @inode: inode to check permissions on 32347291baaSChristian Brauner * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...) 3245fc475b7SLinus Torvalds * 32547291baaSChristian Brauner * This function performs the basic UNIX permission checking. Since this 32647291baaSChristian Brauner * function may retrieve POSIX acls it needs to know whether it is called from a 32747291baaSChristian Brauner * blocking or non-blocking context and thus cares about the MAY_NOT_BLOCK bit. 32847291baaSChristian Brauner * 32947291baaSChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 33047291baaSChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 33147291baaSChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 33247291baaSChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 33347291baaSChristian Brauner * raw inode simply passs init_user_ns. 3345909ccaaSLinus Torvalds */ 33547291baaSChristian Brauner static int acl_permission_check(struct user_namespace *mnt_userns, 33647291baaSChristian Brauner struct inode *inode, int mask) 3375909ccaaSLinus Torvalds { 33826cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 33947291baaSChristian Brauner kuid_t i_uid; 3405909ccaaSLinus Torvalds 3415fc475b7SLinus Torvalds /* Are we the owner? If so, ACL's don't matter */ 34247291baaSChristian Brauner i_uid = i_uid_into_mnt(mnt_userns, inode); 34347291baaSChristian Brauner if (likely(uid_eq(current_fsuid(), i_uid))) { 3445fc475b7SLinus Torvalds mask &= 7; 3455909ccaaSLinus Torvalds mode >>= 6; 3465fc475b7SLinus Torvalds return (mask & ~mode) ? -EACCES : 0; 3475fc475b7SLinus Torvalds } 3485fc475b7SLinus Torvalds 3495fc475b7SLinus Torvalds /* Do we have ACL's? */ 350e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 35147291baaSChristian Brauner int error = check_acl(mnt_userns, inode, mask); 3525909ccaaSLinus Torvalds if (error != -EAGAIN) 3535909ccaaSLinus Torvalds return error; 3545909ccaaSLinus Torvalds } 3555909ccaaSLinus Torvalds 3565fc475b7SLinus Torvalds /* Only RWX matters for group/other mode bits */ 3575fc475b7SLinus Torvalds mask &= 7; 3585fc475b7SLinus Torvalds 3595fc475b7SLinus Torvalds /* 3605fc475b7SLinus Torvalds * Are the group permissions different from 3615fc475b7SLinus Torvalds * the other permissions in the bits we care 3625fc475b7SLinus Torvalds * about? Need to check group ownership if so. 3635fc475b7SLinus Torvalds */ 3645fc475b7SLinus Torvalds if (mask & (mode ^ (mode >> 3))) { 36547291baaSChristian Brauner kgid_t kgid = i_gid_into_mnt(mnt_userns, inode); 36647291baaSChristian Brauner if (in_group_p(kgid)) 3675909ccaaSLinus Torvalds mode >>= 3; 3685909ccaaSLinus Torvalds } 3695909ccaaSLinus Torvalds 3705fc475b7SLinus Torvalds /* Bits in 'mode' clear that we require? */ 3715fc475b7SLinus Torvalds return (mask & ~mode) ? -EACCES : 0; 3725909ccaaSLinus Torvalds } 3731da177e4SLinus Torvalds 3741da177e4SLinus Torvalds /** 3751da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 37647291baaSChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 3771da177e4SLinus Torvalds * @inode: inode to check access rights for 3785fc475b7SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, 3795fc475b7SLinus Torvalds * %MAY_NOT_BLOCK ...) 3801da177e4SLinus Torvalds * 3811da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3821da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3831da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 384b74c79e9SNick Piggin * are used for other things. 385b74c79e9SNick Piggin * 386b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 387b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 388b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 38947291baaSChristian Brauner * 39047291baaSChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 39147291baaSChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 39247291baaSChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 39347291baaSChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 39447291baaSChristian Brauner * raw inode simply passs init_user_ns. 3951da177e4SLinus Torvalds */ 39647291baaSChristian Brauner int generic_permission(struct user_namespace *mnt_userns, struct inode *inode, 39747291baaSChristian Brauner int mask) 3981da177e4SLinus Torvalds { 3995909ccaaSLinus Torvalds int ret; 4001da177e4SLinus Torvalds 4011da177e4SLinus Torvalds /* 402948409c7SAndreas Gruenbacher * Do the basic permission checks. 4031da177e4SLinus Torvalds */ 40447291baaSChristian Brauner ret = acl_permission_check(mnt_userns, inode, mask); 4055909ccaaSLinus Torvalds if (ret != -EACCES) 4065909ccaaSLinus Torvalds return ret; 4071da177e4SLinus Torvalds 408d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 409d594e7ecSAl Viro /* DACs are overridable for directories */ 410d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 41147291baaSChristian Brauner if (capable_wrt_inode_uidgid(mnt_userns, inode, 41223adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 413d594e7ecSAl Viro return 0; 41447291baaSChristian Brauner if (capable_wrt_inode_uidgid(mnt_userns, inode, 4150558c1bfSChristian Brauner CAP_DAC_OVERRIDE)) 4161da177e4SLinus Torvalds return 0; 4172a4c2242SStephen Smalley return -EACCES; 4182a4c2242SStephen Smalley } 4191da177e4SLinus Torvalds 4201da177e4SLinus Torvalds /* 4211da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 4221da177e4SLinus Torvalds */ 4237ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 424d594e7ecSAl Viro if (mask == MAY_READ) 42547291baaSChristian Brauner if (capable_wrt_inode_uidgid(mnt_userns, inode, 4260558c1bfSChristian Brauner CAP_DAC_READ_SEARCH)) 4271da177e4SLinus Torvalds return 0; 4282a4c2242SStephen Smalley /* 4292a4c2242SStephen Smalley * Read/write DACs are always overridable. 4302a4c2242SStephen Smalley * Executable DACs are overridable when there is 4312a4c2242SStephen Smalley * at least one exec bit set. 4322a4c2242SStephen Smalley */ 4332a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 43447291baaSChristian Brauner if (capable_wrt_inode_uidgid(mnt_userns, inode, 4350558c1bfSChristian Brauner CAP_DAC_OVERRIDE)) 4362a4c2242SStephen Smalley return 0; 4371da177e4SLinus Torvalds 4381da177e4SLinus Torvalds return -EACCES; 4391da177e4SLinus Torvalds } 4404d359507SAl Viro EXPORT_SYMBOL(generic_permission); 4411da177e4SLinus Torvalds 44247291baaSChristian Brauner /** 44347291baaSChristian Brauner * do_inode_permission - UNIX permission checking 44447291baaSChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 44547291baaSChristian Brauner * @inode: inode to check permissions on 44647291baaSChristian Brauner * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...) 44747291baaSChristian Brauner * 4483ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 4493ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 4503ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 4513ddcd056SLinus Torvalds * permission function, use the fast case". 4523ddcd056SLinus Torvalds */ 45347291baaSChristian Brauner static inline int do_inode_permission(struct user_namespace *mnt_userns, 45447291baaSChristian Brauner struct inode *inode, int mask) 4553ddcd056SLinus Torvalds { 4563ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 4573ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 458549c7297SChristian Brauner return inode->i_op->permission(mnt_userns, inode, mask); 4593ddcd056SLinus Torvalds 4603ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 4613ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 4623ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 4633ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 4643ddcd056SLinus Torvalds } 46547291baaSChristian Brauner return generic_permission(mnt_userns, inode, mask); 4663ddcd056SLinus Torvalds } 4673ddcd056SLinus Torvalds 468cb23beb5SChristoph Hellwig /** 4690bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4700bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 47155852635SRandy Dunlap * @inode: Inode to check permission on 4720bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4730bdaea90SDavid Howells * 4740bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4750bdaea90SDavid Howells */ 4760bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4770bdaea90SDavid Howells { 4780bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4790bdaea90SDavid Howells umode_t mode = inode->i_mode; 4800bdaea90SDavid Howells 4810bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 482bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4830bdaea90SDavid Howells return -EROFS; 4840bdaea90SDavid Howells } 4850bdaea90SDavid Howells return 0; 4860bdaea90SDavid Howells } 4870bdaea90SDavid Howells 4880bdaea90SDavid Howells /** 4890bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 49047291baaSChristian Brauner * @mnt_userns: User namespace of the mount the inode was found from 4910bdaea90SDavid Howells * @inode: Inode to check permission on 4920bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4930bdaea90SDavid Howells * 4940bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4950bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4960bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4970bdaea90SDavid Howells * 4980bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4990bdaea90SDavid Howells */ 50047291baaSChristian Brauner int inode_permission(struct user_namespace *mnt_userns, 50147291baaSChristian Brauner struct inode *inode, int mask) 5020bdaea90SDavid Howells { 5030bdaea90SDavid Howells int retval; 5040bdaea90SDavid Howells 5050bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 5060bdaea90SDavid Howells if (retval) 5070bdaea90SDavid Howells return retval; 5084bfd054aSEric Biggers 5094bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 5104bfd054aSEric Biggers /* 5114bfd054aSEric Biggers * Nobody gets write access to an immutable file. 5124bfd054aSEric Biggers */ 5134bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 5144bfd054aSEric Biggers return -EPERM; 5154bfd054aSEric Biggers 5164bfd054aSEric Biggers /* 5174bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 5184bfd054aSEric Biggers * written back improperly if their true value is unknown 5194bfd054aSEric Biggers * to the vfs. 5204bfd054aSEric Biggers */ 521ba73d987SChristian Brauner if (HAS_UNMAPPED_ID(mnt_userns, inode)) 5224bfd054aSEric Biggers return -EACCES; 5234bfd054aSEric Biggers } 5244bfd054aSEric Biggers 52547291baaSChristian Brauner retval = do_inode_permission(mnt_userns, inode, mask); 5264bfd054aSEric Biggers if (retval) 5274bfd054aSEric Biggers return retval; 5284bfd054aSEric Biggers 5294bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 5304bfd054aSEric Biggers if (retval) 5314bfd054aSEric Biggers return retval; 5324bfd054aSEric Biggers 5334bfd054aSEric Biggers return security_inode_permission(inode, mask); 5340bdaea90SDavid Howells } 5354d359507SAl Viro EXPORT_SYMBOL(inode_permission); 5360bdaea90SDavid Howells 5370bdaea90SDavid Howells /** 5385dd784d0SJan Blunck * path_get - get a reference to a path 5395dd784d0SJan Blunck * @path: path to get the reference to 5405dd784d0SJan Blunck * 5415dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 5425dd784d0SJan Blunck */ 543dcf787f3SAl Viro void path_get(const struct path *path) 5445dd784d0SJan Blunck { 5455dd784d0SJan Blunck mntget(path->mnt); 5465dd784d0SJan Blunck dget(path->dentry); 5475dd784d0SJan Blunck } 5485dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 5495dd784d0SJan Blunck 5505dd784d0SJan Blunck /** 5511d957f9bSJan Blunck * path_put - put a reference to a path 5521d957f9bSJan Blunck * @path: path to put the reference to 5531d957f9bSJan Blunck * 5541d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 5551d957f9bSJan Blunck */ 556dcf787f3SAl Viro void path_put(const struct path *path) 5571da177e4SLinus Torvalds { 5581d957f9bSJan Blunck dput(path->dentry); 5591d957f9bSJan Blunck mntput(path->mnt); 5601da177e4SLinus Torvalds } 5611d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 5621da177e4SLinus Torvalds 563894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 5641f55a6ecSAl Viro struct nameidata { 5651f55a6ecSAl Viro struct path path; 5661f55a6ecSAl Viro struct qstr last; 5671f55a6ecSAl Viro struct path root; 5681f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 569bcba1e7dSAl Viro unsigned int flags, state; 570ab87f9a5SAleksa Sarai unsigned seq, m_seq, r_seq; 5711f55a6ecSAl Viro int last_type; 5721f55a6ecSAl Viro unsigned depth; 573756daf26SNeilBrown int total_link_count; 574697fc6caSAl Viro struct saved { 575697fc6caSAl Viro struct path link; 576fceef393SAl Viro struct delayed_call done; 577697fc6caSAl Viro const char *name; 5780450b2d1SAl Viro unsigned seq; 579894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5809883d185SAl Viro struct filename *name; 5819883d185SAl Viro struct nameidata *saved; 5829883d185SAl Viro unsigned root_seq; 5839883d185SAl Viro int dfd; 5840f705953SAl Viro kuid_t dir_uid; 5850f705953SAl Viro umode_t dir_mode; 5863859a271SKees Cook } __randomize_layout; 5871f55a6ecSAl Viro 588bcba1e7dSAl Viro #define ND_ROOT_PRESET 1 589bcba1e7dSAl Viro #define ND_ROOT_GRABBED 2 590bcba1e7dSAl Viro #define ND_JUMPED 4 591bcba1e7dSAl Viro 59206422964SAl Viro static void __set_nameidata(struct nameidata *p, int dfd, struct filename *name) 593894bc8c4SAl Viro { 594756daf26SNeilBrown struct nameidata *old = current->nameidata; 595756daf26SNeilBrown p->stack = p->internal; 5967962c7d1SAl Viro p->depth = 0; 597c8a53ee5SAl Viro p->dfd = dfd; 598c8a53ee5SAl Viro p->name = name; 5997d01ef75SAl Viro p->path.mnt = NULL; 6007d01ef75SAl Viro p->path.dentry = NULL; 601756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 6029883d185SAl Viro p->saved = old; 603756daf26SNeilBrown current->nameidata = p; 604894bc8c4SAl Viro } 605894bc8c4SAl Viro 60606422964SAl Viro static inline void set_nameidata(struct nameidata *p, int dfd, struct filename *name, 60706422964SAl Viro const struct path *root) 60806422964SAl Viro { 60906422964SAl Viro __set_nameidata(p, dfd, name); 61006422964SAl Viro p->state = 0; 61106422964SAl Viro if (unlikely(root)) { 61206422964SAl Viro p->state = ND_ROOT_PRESET; 61306422964SAl Viro p->root = *root; 61406422964SAl Viro } 61506422964SAl Viro } 61606422964SAl Viro 6179883d185SAl Viro static void restore_nameidata(void) 618894bc8c4SAl Viro { 6199883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 620756daf26SNeilBrown 621756daf26SNeilBrown current->nameidata = old; 622756daf26SNeilBrown if (old) 623756daf26SNeilBrown old->total_link_count = now->total_link_count; 624e1a63bbcSAl Viro if (now->stack != now->internal) 625756daf26SNeilBrown kfree(now->stack); 626894bc8c4SAl Viro } 627894bc8c4SAl Viro 62860ef60c7SAl Viro static bool nd_alloc_stack(struct nameidata *nd) 629894bc8c4SAl Viro { 630bc40aee0SAl Viro struct saved *p; 631bc40aee0SAl Viro 6326da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 63360ef60c7SAl Viro nd->flags & LOOKUP_RCU ? GFP_ATOMIC : GFP_KERNEL); 634bc40aee0SAl Viro if (unlikely(!p)) 63560ef60c7SAl Viro return false; 636894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 637894bc8c4SAl Viro nd->stack = p; 63860ef60c7SAl Viro return true; 639894bc8c4SAl Viro } 640894bc8c4SAl Viro 641397d425dSEric W. Biederman /** 6426b03f7edSAl Viro * path_connected - Verify that a dentry is below mnt.mnt_root 643397d425dSEric W. Biederman * 644397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 645397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 646397d425dSEric W. Biederman */ 6476b03f7edSAl Viro static bool path_connected(struct vfsmount *mnt, struct dentry *dentry) 648397d425dSEric W. Biederman { 64995dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 650397d425dSEric W. Biederman 651402dd2cfSChristoph Hellwig /* Bind mounts can have disconnected paths */ 652402dd2cfSChristoph Hellwig if (mnt->mnt_root == sb->s_root) 653397d425dSEric W. Biederman return true; 654397d425dSEric W. Biederman 6556b03f7edSAl Viro return is_subdir(dentry, mnt->mnt_root); 656397d425dSEric W. Biederman } 657397d425dSEric W. Biederman 6587973387aSAl Viro static void drop_links(struct nameidata *nd) 6597973387aSAl Viro { 6607973387aSAl Viro int i = nd->depth; 6617973387aSAl Viro while (i--) { 6627973387aSAl Viro struct saved *last = nd->stack + i; 663fceef393SAl Viro do_delayed_call(&last->done); 664fceef393SAl Viro clear_delayed_call(&last->done); 6657973387aSAl Viro } 6667973387aSAl Viro } 6677973387aSAl Viro 6687973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6697973387aSAl Viro { 6707973387aSAl Viro drop_links(nd); 6717973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6727973387aSAl Viro int i; 6737973387aSAl Viro path_put(&nd->path); 6747973387aSAl Viro for (i = 0; i < nd->depth; i++) 6757973387aSAl Viro path_put(&nd->stack[i].link); 676bcba1e7dSAl Viro if (nd->state & ND_ROOT_GRABBED) { 677102b8af2SAl Viro path_put(&nd->root); 678bcba1e7dSAl Viro nd->state &= ~ND_ROOT_GRABBED; 679102b8af2SAl Viro } 6807973387aSAl Viro } else { 6817973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6827973387aSAl Viro rcu_read_unlock(); 6837973387aSAl Viro } 6847973387aSAl Viro nd->depth = 0; 6857d01ef75SAl Viro nd->path.mnt = NULL; 6867d01ef75SAl Viro nd->path.dentry = NULL; 6877973387aSAl Viro } 6887973387aSAl Viro 6897973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6902aa38470SAl Viro static bool __legitimize_path(struct path *path, unsigned seq, unsigned mseq) 6917973387aSAl Viro { 6922aa38470SAl Viro int res = __legitimize_mnt(path->mnt, mseq); 6937973387aSAl Viro if (unlikely(res)) { 6947973387aSAl Viro if (res > 0) 6957973387aSAl Viro path->mnt = NULL; 6967973387aSAl Viro path->dentry = NULL; 6977973387aSAl Viro return false; 6987973387aSAl Viro } 6997973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 7007973387aSAl Viro path->dentry = NULL; 7017973387aSAl Viro return false; 7027973387aSAl Viro } 7037973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 7047973387aSAl Viro } 7057973387aSAl Viro 7062aa38470SAl Viro static inline bool legitimize_path(struct nameidata *nd, 7072aa38470SAl Viro struct path *path, unsigned seq) 7082aa38470SAl Viro { 7095bd73286SAl Viro return __legitimize_path(path, seq, nd->m_seq); 7102aa38470SAl Viro } 7112aa38470SAl Viro 7127973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 7137973387aSAl Viro { 7147973387aSAl Viro int i; 715eacd9aa8SAl Viro if (unlikely(nd->flags & LOOKUP_CACHED)) { 716eacd9aa8SAl Viro drop_links(nd); 717eacd9aa8SAl Viro nd->depth = 0; 718eacd9aa8SAl Viro return false; 719eacd9aa8SAl Viro } 7207973387aSAl Viro for (i = 0; i < nd->depth; i++) { 7217973387aSAl Viro struct saved *last = nd->stack + i; 7227973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 7237973387aSAl Viro drop_links(nd); 7247973387aSAl Viro nd->depth = i + 1; 7257973387aSAl Viro return false; 7267973387aSAl Viro } 7277973387aSAl Viro } 7287973387aSAl Viro return true; 7297973387aSAl Viro } 7307973387aSAl Viro 731ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 732ee594bffSAl Viro { 733adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 734bcba1e7dSAl Viro if (!nd->root.mnt || (nd->state & ND_ROOT_PRESET)) 735ee594bffSAl Viro return true; 736bcba1e7dSAl Viro nd->state |= ND_ROOT_GRABBED; 737ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 738ee594bffSAl Viro } 739ee594bffSAl Viro 74019660af7SAl Viro /* 74131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 74219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 74319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 74457e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 74519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 74619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 74719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 74819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 74931e6b01fSNick Piggin */ 75031e6b01fSNick Piggin 75131e6b01fSNick Piggin /** 752e36cffedSJens Axboe * try_to_unlazy - try to switch to ref-walk mode. 75319660af7SAl Viro * @nd: nameidata pathwalk data 754e36cffedSJens Axboe * Returns: true on success, false on failure 75531e6b01fSNick Piggin * 756e36cffedSJens Axboe * try_to_unlazy attempts to legitimize the current nd->path and nd->root 7574675ac39SAl Viro * for ref-walk mode. 7584675ac39SAl Viro * Must be called from rcu-walk context. 759e36cffedSJens Axboe * Nothing should touch nameidata between try_to_unlazy() failure and 7607973387aSAl Viro * terminate_walk(). 76131e6b01fSNick Piggin */ 762e36cffedSJens Axboe static bool try_to_unlazy(struct nameidata *nd) 76331e6b01fSNick Piggin { 76431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 76531e6b01fSNick Piggin 76631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 767e5c832d5SLinus Torvalds 768e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 7697973387aSAl Viro if (unlikely(!legitimize_links(nd))) 7704675ac39SAl Viro goto out1; 77184a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 77284a2bd39SAl Viro goto out; 773ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 7744675ac39SAl Viro goto out; 7754675ac39SAl Viro rcu_read_unlock(); 7764675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 777e36cffedSJens Axboe return true; 7784675ac39SAl Viro 77984a2bd39SAl Viro out1: 7804675ac39SAl Viro nd->path.mnt = NULL; 7814675ac39SAl Viro nd->path.dentry = NULL; 7824675ac39SAl Viro out: 7834675ac39SAl Viro rcu_read_unlock(); 784e36cffedSJens Axboe return false; 7854675ac39SAl Viro } 7864675ac39SAl Viro 7874675ac39SAl Viro /** 788ae66db45SAl Viro * try_to_unlazy_next - try to switch to ref-walk mode. 7894675ac39SAl Viro * @nd: nameidata pathwalk data 790ae66db45SAl Viro * @dentry: next dentry to step into 791ae66db45SAl Viro * @seq: seq number to check @dentry against 792ae66db45SAl Viro * Returns: true on success, false on failure 7934675ac39SAl Viro * 79430476f7eSTom Rix * Similar to try_to_unlazy(), but here we have the next dentry already 795ae66db45SAl Viro * picked by rcu-walk and want to legitimize that in addition to the current 796ae66db45SAl Viro * nd->path and nd->root for ref-walk mode. Must be called from rcu-walk context. 797ae66db45SAl Viro * Nothing should touch nameidata between try_to_unlazy_next() failure and 7984675ac39SAl Viro * terminate_walk(). 7994675ac39SAl Viro */ 800ae66db45SAl Viro static bool try_to_unlazy_next(struct nameidata *nd, struct dentry *dentry, unsigned seq) 8014675ac39SAl Viro { 8024675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 8034675ac39SAl Viro 8044675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 8054675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 8064675ac39SAl Viro goto out2; 8077973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 8087973387aSAl Viro goto out2; 8094675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 8107973387aSAl Viro goto out1; 81148a066e7SAl Viro 81215570086SLinus Torvalds /* 8134675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 8144675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 8154675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 8164675ac39SAl Viro * number of the parent after we got the child sequence number. So we 8174675ac39SAl Viro * know the parent must still be valid if the child sequence number is 81815570086SLinus Torvalds */ 8194675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 820e5c832d5SLinus Torvalds goto out; 821*82ef0698SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 82284a2bd39SAl Viro goto out_dput; 823e5c832d5SLinus Torvalds /* 824e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 825e5c832d5SLinus Torvalds * still valid and get it if required. 826e5c832d5SLinus Torvalds */ 82784a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 82884a2bd39SAl Viro goto out_dput; 8298b61e74fSAl Viro rcu_read_unlock(); 830ae66db45SAl Viro return true; 83119660af7SAl Viro 8327973387aSAl Viro out2: 8337973387aSAl Viro nd->path.mnt = NULL; 8347973387aSAl Viro out1: 8357973387aSAl Viro nd->path.dentry = NULL; 836e5c832d5SLinus Torvalds out: 8378b61e74fSAl Viro rcu_read_unlock(); 838ae66db45SAl Viro return false; 83984a2bd39SAl Viro out_dput: 84084a2bd39SAl Viro rcu_read_unlock(); 84184a2bd39SAl Viro dput(dentry); 842ae66db45SAl Viro return false; 84331e6b01fSNick Piggin } 84431e6b01fSNick Piggin 8454ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 84634286d66SNick Piggin { 847a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 8484ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 849a89f8337SAl Viro else 850a89f8337SAl Viro return 1; 85134286d66SNick Piggin } 85234286d66SNick Piggin 8539f1fafeeSAl Viro /** 8549f1fafeeSAl Viro * complete_walk - successful completion of path walk 8559f1fafeeSAl Viro * @nd: pointer nameidata 85639159de2SJeff Layton * 8579f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 8589f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 8599f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 8609f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 8619f1fafeeSAl Viro * need to drop nd->path. 86239159de2SJeff Layton */ 8639f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 86439159de2SJeff Layton { 86516c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 86639159de2SJeff Layton int status; 86739159de2SJeff Layton 8689f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 869adb21d2bSAleksa Sarai /* 870adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 871adb21d2bSAleksa Sarai * externally-managed nd->root. 872adb21d2bSAleksa Sarai */ 873bcba1e7dSAl Viro if (!(nd->state & ND_ROOT_PRESET)) 874bcba1e7dSAl Viro if (!(nd->flags & LOOKUP_IS_SCOPED)) 8759f1fafeeSAl Viro nd->root.mnt = NULL; 8766c6ec2b0SJens Axboe nd->flags &= ~LOOKUP_CACHED; 877e36cffedSJens Axboe if (!try_to_unlazy(nd)) 87848a066e7SAl Viro return -ECHILD; 87948a066e7SAl Viro } 8809f1fafeeSAl Viro 881adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 882adb21d2bSAleksa Sarai /* 883adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 884adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 885adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 886adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 887adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 888adb21d2bSAleksa Sarai * 889adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 890adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 891adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 892adb21d2bSAleksa Sarai * requested root to userspace. 893adb21d2bSAleksa Sarai * 894adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 895adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 896adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 897adb21d2bSAleksa Sarai */ 898adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 899adb21d2bSAleksa Sarai return -EXDEV; 900adb21d2bSAleksa Sarai } 901adb21d2bSAleksa Sarai 902bcba1e7dSAl Viro if (likely(!(nd->state & ND_JUMPED))) 90339159de2SJeff Layton return 0; 90439159de2SJeff Layton 905ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 90616c2cd71SAl Viro return 0; 90716c2cd71SAl Viro 908ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 90939159de2SJeff Layton if (status > 0) 91039159de2SJeff Layton return 0; 91139159de2SJeff Layton 91216c2cd71SAl Viro if (!status) 91339159de2SJeff Layton status = -ESTALE; 91416c2cd71SAl Viro 91539159de2SJeff Layton return status; 91639159de2SJeff Layton } 91739159de2SJeff Layton 918740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 9192a737871SAl Viro { 92031e6b01fSNick Piggin struct fs_struct *fs = current->fs; 9219e6697e2SAl Viro 922adb21d2bSAleksa Sarai /* 923adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 924adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 925adb21d2bSAleksa Sarai * from the dirfd. 926adb21d2bSAleksa Sarai */ 927adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 928adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 929adb21d2bSAleksa Sarai 9309e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 9318f47a016SAl Viro unsigned seq; 932c28cc364SNick Piggin 933c28cc364SNick Piggin do { 934c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 93531e6b01fSNick Piggin nd->root = fs->root; 9368f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 937c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 9389e6697e2SAl Viro } else { 9399e6697e2SAl Viro get_fs_root(fs, &nd->root); 940bcba1e7dSAl Viro nd->state |= ND_ROOT_GRABBED; 9419e6697e2SAl Viro } 942740a1678SAleksa Sarai return 0; 94331e6b01fSNick Piggin } 94431e6b01fSNick Piggin 945248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 946248fb5b9SAl Viro { 947adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 948adb21d2bSAleksa Sarai return -EXDEV; 94972ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 95072ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 95172ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 95272ba2929SAleksa Sarai return -EXDEV; 95372ba2929SAleksa Sarai } 954740a1678SAleksa Sarai if (!nd->root.mnt) { 955740a1678SAleksa Sarai int error = set_root(nd); 956740a1678SAleksa Sarai if (error) 957740a1678SAleksa Sarai return error; 958740a1678SAleksa Sarai } 959248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 960248fb5b9SAl Viro struct dentry *d; 961248fb5b9SAl Viro nd->path = nd->root; 962248fb5b9SAl Viro d = nd->path.dentry; 963248fb5b9SAl Viro nd->inode = d->d_inode; 964248fb5b9SAl Viro nd->seq = nd->root_seq; 965*82ef0698SAl Viro if (read_seqcount_retry(&d->d_seq, nd->seq)) 966248fb5b9SAl Viro return -ECHILD; 967248fb5b9SAl Viro } else { 968248fb5b9SAl Viro path_put(&nd->path); 969248fb5b9SAl Viro nd->path = nd->root; 970248fb5b9SAl Viro path_get(&nd->path); 971248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 972248fb5b9SAl Viro } 973bcba1e7dSAl Viro nd->state |= ND_JUMPED; 974248fb5b9SAl Viro return 0; 975248fb5b9SAl Viro } 976248fb5b9SAl Viro 977b5fb63c1SChristoph Hellwig /* 9786b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 979b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 980b5fb63c1SChristoph Hellwig */ 9811bc82070SAleksa Sarai int nd_jump_link(struct path *path) 982b5fb63c1SChristoph Hellwig { 9834b99d499SAleksa Sarai int error = -ELOOP; 9846e77137bSAl Viro struct nameidata *nd = current->nameidata; 985b5fb63c1SChristoph Hellwig 9864b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 9874b99d499SAleksa Sarai goto err; 9884b99d499SAleksa Sarai 98972ba2929SAleksa Sarai error = -EXDEV; 99072ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 99172ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 99272ba2929SAleksa Sarai goto err; 99372ba2929SAleksa Sarai } 994adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 995adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 996adb21d2bSAleksa Sarai goto err; 99772ba2929SAleksa Sarai 9984b99d499SAleksa Sarai path_put(&nd->path); 999b5fb63c1SChristoph Hellwig nd->path = *path; 1000b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 1001bcba1e7dSAl Viro nd->state |= ND_JUMPED; 10021bc82070SAleksa Sarai return 0; 10034b99d499SAleksa Sarai 10044b99d499SAleksa Sarai err: 10054b99d499SAleksa Sarai path_put(path); 10064b99d499SAleksa Sarai return error; 1007b5fb63c1SChristoph Hellwig } 1008b5fb63c1SChristoph Hellwig 1009b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 1010574197e0SAl Viro { 101121c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 1012fceef393SAl Viro do_delayed_call(&last->done); 10136548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 1014b9ff4429SAl Viro path_put(&last->link); 1015574197e0SAl Viro } 1016574197e0SAl Viro 10179c011be1SLuis Chamberlain static int sysctl_protected_symlinks __read_mostly; 10189c011be1SLuis Chamberlain static int sysctl_protected_hardlinks __read_mostly; 10199c011be1SLuis Chamberlain static int sysctl_protected_fifos __read_mostly; 10209c011be1SLuis Chamberlain static int sysctl_protected_regular __read_mostly; 10219c011be1SLuis Chamberlain 10229c011be1SLuis Chamberlain #ifdef CONFIG_SYSCTL 10239c011be1SLuis Chamberlain static struct ctl_table namei_sysctls[] = { 10249c011be1SLuis Chamberlain { 10259c011be1SLuis Chamberlain .procname = "protected_symlinks", 10269c011be1SLuis Chamberlain .data = &sysctl_protected_symlinks, 10279c011be1SLuis Chamberlain .maxlen = sizeof(int), 1028c7031c14SJulius Hemanth Pitti .mode = 0644, 10299c011be1SLuis Chamberlain .proc_handler = proc_dointvec_minmax, 10309c011be1SLuis Chamberlain .extra1 = SYSCTL_ZERO, 10319c011be1SLuis Chamberlain .extra2 = SYSCTL_ONE, 10329c011be1SLuis Chamberlain }, 10339c011be1SLuis Chamberlain { 10349c011be1SLuis Chamberlain .procname = "protected_hardlinks", 10359c011be1SLuis Chamberlain .data = &sysctl_protected_hardlinks, 10369c011be1SLuis Chamberlain .maxlen = sizeof(int), 1037c7031c14SJulius Hemanth Pitti .mode = 0644, 10389c011be1SLuis Chamberlain .proc_handler = proc_dointvec_minmax, 10399c011be1SLuis Chamberlain .extra1 = SYSCTL_ZERO, 10409c011be1SLuis Chamberlain .extra2 = SYSCTL_ONE, 10419c011be1SLuis Chamberlain }, 10429c011be1SLuis Chamberlain { 10439c011be1SLuis Chamberlain .procname = "protected_fifos", 10449c011be1SLuis Chamberlain .data = &sysctl_protected_fifos, 10459c011be1SLuis Chamberlain .maxlen = sizeof(int), 1046c7031c14SJulius Hemanth Pitti .mode = 0644, 10479c011be1SLuis Chamberlain .proc_handler = proc_dointvec_minmax, 10489c011be1SLuis Chamberlain .extra1 = SYSCTL_ZERO, 10499c011be1SLuis Chamberlain .extra2 = SYSCTL_TWO, 10509c011be1SLuis Chamberlain }, 10519c011be1SLuis Chamberlain { 10529c011be1SLuis Chamberlain .procname = "protected_regular", 10539c011be1SLuis Chamberlain .data = &sysctl_protected_regular, 10549c011be1SLuis Chamberlain .maxlen = sizeof(int), 1055c7031c14SJulius Hemanth Pitti .mode = 0644, 10569c011be1SLuis Chamberlain .proc_handler = proc_dointvec_minmax, 10579c011be1SLuis Chamberlain .extra1 = SYSCTL_ZERO, 10589c011be1SLuis Chamberlain .extra2 = SYSCTL_TWO, 10599c011be1SLuis Chamberlain }, 10609c011be1SLuis Chamberlain { } 10619c011be1SLuis Chamberlain }; 10629c011be1SLuis Chamberlain 10639c011be1SLuis Chamberlain static int __init init_fs_namei_sysctls(void) 10649c011be1SLuis Chamberlain { 10659c011be1SLuis Chamberlain register_sysctl_init("fs", namei_sysctls); 10669c011be1SLuis Chamberlain return 0; 10679c011be1SLuis Chamberlain } 10689c011be1SLuis Chamberlain fs_initcall(init_fs_namei_sysctls); 10699c011be1SLuis Chamberlain 10709c011be1SLuis Chamberlain #endif /* CONFIG_SYSCTL */ 1071800179c9SKees Cook 1072800179c9SKees Cook /** 1073800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 107455852635SRandy Dunlap * @nd: nameidata pathwalk data 1075800179c9SKees Cook * 1076800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 1077800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 1078800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 1079800179c9SKees Cook * processes from failing races against path names that may change out 1080800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 1081800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 1082800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 1083800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 1084800179c9SKees Cook * 1085800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 1086800179c9SKees Cook */ 1087ad6cc4c3SAl Viro static inline int may_follow_link(struct nameidata *nd, const struct inode *inode) 1088800179c9SKees Cook { 1089ba73d987SChristian Brauner struct user_namespace *mnt_userns; 1090ba73d987SChristian Brauner kuid_t i_uid; 1091ba73d987SChristian Brauner 1092800179c9SKees Cook if (!sysctl_protected_symlinks) 1093800179c9SKees Cook return 0; 1094800179c9SKees Cook 1095ba73d987SChristian Brauner mnt_userns = mnt_user_ns(nd->path.mnt); 1096ba73d987SChristian Brauner i_uid = i_uid_into_mnt(mnt_userns, inode); 1097800179c9SKees Cook /* Allowed if owner and follower match. */ 1098ba73d987SChristian Brauner if (uid_eq(current_cred()->fsuid, i_uid)) 1099800179c9SKees Cook return 0; 1100800179c9SKees Cook 1101800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 11020f705953SAl Viro if ((nd->dir_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 1103800179c9SKees Cook return 0; 1104800179c9SKees Cook 1105800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 1106ba73d987SChristian Brauner if (uid_valid(nd->dir_uid) && uid_eq(nd->dir_uid, i_uid)) 1107800179c9SKees Cook return 0; 1108800179c9SKees Cook 110931956502SAl Viro if (nd->flags & LOOKUP_RCU) 111031956502SAl Viro return -ECHILD; 111131956502SAl Viro 1112ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 1113245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 1114800179c9SKees Cook return -EACCES; 1115800179c9SKees Cook } 1116800179c9SKees Cook 1117800179c9SKees Cook /** 1118800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 1119ba73d987SChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 1120800179c9SKees Cook * @inode: the source inode to hardlink from 1121800179c9SKees Cook * 1122800179c9SKees Cook * Return false if at least one of the following conditions: 1123800179c9SKees Cook * - inode is not a regular file 1124800179c9SKees Cook * - inode is setuid 1125800179c9SKees Cook * - inode is setgid and group-exec 1126800179c9SKees Cook * - access failure for read and write 1127800179c9SKees Cook * 1128800179c9SKees Cook * Otherwise returns true. 1129800179c9SKees Cook */ 1130ba73d987SChristian Brauner static bool safe_hardlink_source(struct user_namespace *mnt_userns, 1131ba73d987SChristian Brauner struct inode *inode) 1132800179c9SKees Cook { 1133800179c9SKees Cook umode_t mode = inode->i_mode; 1134800179c9SKees Cook 1135800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1136800179c9SKees Cook if (!S_ISREG(mode)) 1137800179c9SKees Cook return false; 1138800179c9SKees Cook 1139800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1140800179c9SKees Cook if (mode & S_ISUID) 1141800179c9SKees Cook return false; 1142800179c9SKees Cook 1143800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1144800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1145800179c9SKees Cook return false; 1146800179c9SKees Cook 1147800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 1148ba73d987SChristian Brauner if (inode_permission(mnt_userns, inode, MAY_READ | MAY_WRITE)) 1149800179c9SKees Cook return false; 1150800179c9SKees Cook 1151800179c9SKees Cook return true; 1152800179c9SKees Cook } 1153800179c9SKees Cook 1154800179c9SKees Cook /** 1155800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 1156ba73d987SChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 1157800179c9SKees Cook * @link: the source to hardlink from 1158800179c9SKees Cook * 1159800179c9SKees Cook * Block hardlink when all of: 1160800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1161800179c9SKees Cook * - fsuid does not match inode 1162800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1163f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1164800179c9SKees Cook * 1165ba73d987SChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 1166ba73d987SChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 1167ba73d987SChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 1168ba73d987SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 1169ba73d987SChristian Brauner * raw inode simply passs init_user_ns. 1170ba73d987SChristian Brauner * 1171800179c9SKees Cook * Returns 0 if successful, -ve on error. 1172800179c9SKees Cook */ 1173ba73d987SChristian Brauner int may_linkat(struct user_namespace *mnt_userns, struct path *link) 1174800179c9SKees Cook { 1175593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1176593d1ce8SEric W. Biederman 1177593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1178ba73d987SChristian Brauner if (!uid_valid(i_uid_into_mnt(mnt_userns, inode)) || 1179ba73d987SChristian Brauner !gid_valid(i_gid_into_mnt(mnt_userns, inode))) 1180593d1ce8SEric W. Biederman return -EOVERFLOW; 1181800179c9SKees Cook 1182800179c9SKees Cook if (!sysctl_protected_hardlinks) 1183800179c9SKees Cook return 0; 1184800179c9SKees Cook 1185800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1186800179c9SKees Cook * otherwise, it must be a safe source. 1187800179c9SKees Cook */ 1188ba73d987SChristian Brauner if (safe_hardlink_source(mnt_userns, inode) || 1189ba73d987SChristian Brauner inode_owner_or_capable(mnt_userns, inode)) 1190800179c9SKees Cook return 0; 1191800179c9SKees Cook 1192245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1193800179c9SKees Cook return -EPERM; 1194800179c9SKees Cook } 1195800179c9SKees Cook 119630aba665SSalvatore Mesoraca /** 119730aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 119830aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 119930aba665SSalvatore Mesoraca * exist. 1200ba73d987SChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 12012111c3c0SRandy Dunlap * @nd: nameidata pathwalk data 120230aba665SSalvatore Mesoraca * @inode: the inode of the file to open 120330aba665SSalvatore Mesoraca * 120430aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 120530aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 120630aba665SSalvatore Mesoraca * - the file already exists 120730aba665SSalvatore Mesoraca * - we are in a sticky directory 120830aba665SSalvatore Mesoraca * - we don't own the file 120930aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 121030aba665SSalvatore Mesoraca * - the directory is world writable 121130aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 121230aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 121330aba665SSalvatore Mesoraca * be enough. 121430aba665SSalvatore Mesoraca * 1215ba73d987SChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 1216ba73d987SChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 1217ba73d987SChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 1218ba73d987SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 1219ba73d987SChristian Brauner * raw inode simply passs init_user_ns. 1220ba73d987SChristian Brauner * 122130aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 122230aba665SSalvatore Mesoraca */ 1223ba73d987SChristian Brauner static int may_create_in_sticky(struct user_namespace *mnt_userns, 1224ba73d987SChristian Brauner struct nameidata *nd, struct inode *const inode) 122530aba665SSalvatore Mesoraca { 1226ba73d987SChristian Brauner umode_t dir_mode = nd->dir_mode; 1227ba73d987SChristian Brauner kuid_t dir_uid = nd->dir_uid; 1228ba73d987SChristian Brauner 122930aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 123030aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1231d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1232ba73d987SChristian Brauner uid_eq(i_uid_into_mnt(mnt_userns, inode), dir_uid) || 1233ba73d987SChristian Brauner uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode))) 123430aba665SSalvatore Mesoraca return 0; 123530aba665SSalvatore Mesoraca 1236d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1237d0cb5018SAl Viro (dir_mode & 0020 && 123830aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 123930aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1240245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1241245d7369SKees Cook "sticky_create_fifo" : 1242245d7369SKees Cook "sticky_create_regular"; 1243245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 124430aba665SSalvatore Mesoraca return -EACCES; 124530aba665SSalvatore Mesoraca } 124630aba665SSalvatore Mesoraca return 0; 124730aba665SSalvatore Mesoraca } 124830aba665SSalvatore Mesoraca 1249f015f126SDavid Howells /* 1250f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1251f015f126SDavid Howells * 1252f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1253f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1254f015f126SDavid Howells * Up is towards /. 1255f015f126SDavid Howells * 1256f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1257f015f126SDavid Howells * root. 1258f015f126SDavid Howells */ 1259bab77ebfSAl Viro int follow_up(struct path *path) 12601da177e4SLinus Torvalds { 12610714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 12620714a533SAl Viro struct mount *parent; 12631da177e4SLinus Torvalds struct dentry *mountpoint; 126499b7db7bSNick Piggin 126548a066e7SAl Viro read_seqlock_excl(&mount_lock); 12660714a533SAl Viro parent = mnt->mnt_parent; 12673c0a6163SAl Viro if (parent == mnt) { 126848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 12691da177e4SLinus Torvalds return 0; 12701da177e4SLinus Torvalds } 12710714a533SAl Viro mntget(&parent->mnt); 1272a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 127348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1274bab77ebfSAl Viro dput(path->dentry); 1275bab77ebfSAl Viro path->dentry = mountpoint; 1276bab77ebfSAl Viro mntput(path->mnt); 12770714a533SAl Viro path->mnt = &parent->mnt; 12781da177e4SLinus Torvalds return 1; 12791da177e4SLinus Torvalds } 12804d359507SAl Viro EXPORT_SYMBOL(follow_up); 12811da177e4SLinus Torvalds 12827ef482faSAl Viro static bool choose_mountpoint_rcu(struct mount *m, const struct path *root, 12837ef482faSAl Viro struct path *path, unsigned *seqp) 12847ef482faSAl Viro { 12857ef482faSAl Viro while (mnt_has_parent(m)) { 12867ef482faSAl Viro struct dentry *mountpoint = m->mnt_mountpoint; 12877ef482faSAl Viro 12887ef482faSAl Viro m = m->mnt_parent; 12897ef482faSAl Viro if (unlikely(root->dentry == mountpoint && 12907ef482faSAl Viro root->mnt == &m->mnt)) 12917ef482faSAl Viro break; 12927ef482faSAl Viro if (mountpoint != m->mnt.mnt_root) { 12937ef482faSAl Viro path->mnt = &m->mnt; 12947ef482faSAl Viro path->dentry = mountpoint; 12957ef482faSAl Viro *seqp = read_seqcount_begin(&mountpoint->d_seq); 12967ef482faSAl Viro return true; 12977ef482faSAl Viro } 12987ef482faSAl Viro } 12997ef482faSAl Viro return false; 13007ef482faSAl Viro } 13017ef482faSAl Viro 13022aa38470SAl Viro static bool choose_mountpoint(struct mount *m, const struct path *root, 13032aa38470SAl Viro struct path *path) 13042aa38470SAl Viro { 13052aa38470SAl Viro bool found; 13062aa38470SAl Viro 13072aa38470SAl Viro rcu_read_lock(); 13082aa38470SAl Viro while (1) { 13092aa38470SAl Viro unsigned seq, mseq = read_seqbegin(&mount_lock); 13102aa38470SAl Viro 13112aa38470SAl Viro found = choose_mountpoint_rcu(m, root, path, &seq); 13122aa38470SAl Viro if (unlikely(!found)) { 13132aa38470SAl Viro if (!read_seqretry(&mount_lock, mseq)) 13142aa38470SAl Viro break; 13152aa38470SAl Viro } else { 13162aa38470SAl Viro if (likely(__legitimize_path(path, seq, mseq))) 13172aa38470SAl Viro break; 13182aa38470SAl Viro rcu_read_unlock(); 13192aa38470SAl Viro path_put(path); 13202aa38470SAl Viro rcu_read_lock(); 13212aa38470SAl Viro } 13222aa38470SAl Viro } 13232aa38470SAl Viro rcu_read_unlock(); 13242aa38470SAl Viro return found; 13252aa38470SAl Viro } 13262aa38470SAl Viro 1327b5c84bf6SNick Piggin /* 13289875cf80SDavid Howells * Perform an automount 13299875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 13309875cf80SDavid Howells * were called with. 13311da177e4SLinus Torvalds */ 13321c9f5e06SAl Viro static int follow_automount(struct path *path, int *count, unsigned lookup_flags) 133331e6b01fSNick Piggin { 133425e195aaSAl Viro struct dentry *dentry = path->dentry; 13359875cf80SDavid Howells 13360ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 13370ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 13380ec26fd0SMiklos Szeredi * the name. 13390ec26fd0SMiklos Szeredi * 13400ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 13415a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 13420ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 13430ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 13440ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 13450ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 13465a30d8a2SDavid Howells */ 13471c9f5e06SAl Viro if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 13485d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 134925e195aaSAl Viro dentry->d_inode) 13509875cf80SDavid Howells return -EISDIR; 13510ec26fd0SMiklos Szeredi 13521c9f5e06SAl Viro if (count && (*count)++ >= MAXSYMLINKS) 13539875cf80SDavid Howells return -ELOOP; 13549875cf80SDavid Howells 135525e195aaSAl Viro return finish_automount(dentry->d_op->d_automount(path), path); 1356ea5b778aSDavid Howells } 13579875cf80SDavid Howells 13589875cf80SDavid Howells /* 13599deed3ebSAl Viro * mount traversal - out-of-line part. One note on ->d_flags accesses - 13609deed3ebSAl Viro * dentries are pinned but not locked here, so negative dentry can go 13619deed3ebSAl Viro * positive right under us. Use of smp_load_acquire() provides a barrier 13629deed3ebSAl Viro * sufficient for ->d_inode and ->d_flags consistency. 13639875cf80SDavid Howells */ 13649deed3ebSAl Viro static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped, 13659deed3ebSAl Viro int *count, unsigned lookup_flags) 13669875cf80SDavid Howells { 13679deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 13689875cf80SDavid Howells bool need_mntput = false; 13698aef1884SAl Viro int ret = 0; 13709875cf80SDavid Howells 13719deed3ebSAl Viro while (flags & DCACHE_MANAGED_DENTRY) { 1372cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1373cc53ce53SDavid Howells * being held. */ 1374d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1375fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1376508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1377cc53ce53SDavid Howells if (ret < 0) 13788aef1884SAl Viro break; 1379cc53ce53SDavid Howells } 1380cc53ce53SDavid Howells 13819deed3ebSAl Viro if (flags & DCACHE_MOUNTED) { // something's mounted on it.. 13829875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 13839deed3ebSAl Viro if (mounted) { // ... in our namespace 13849875cf80SDavid Howells dput(path->dentry); 13859875cf80SDavid Howells if (need_mntput) 1386463ffb2eSAl Viro mntput(path->mnt); 1387463ffb2eSAl Viro path->mnt = mounted; 1388463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 13899deed3ebSAl Viro // here we know it's positive 13909deed3ebSAl Viro flags = path->dentry->d_flags; 13919875cf80SDavid Howells need_mntput = true; 13929875cf80SDavid Howells continue; 1393463ffb2eSAl Viro } 13941da177e4SLinus Torvalds } 13959875cf80SDavid Howells 13969deed3ebSAl Viro if (!(flags & DCACHE_NEED_AUTOMOUNT)) 13979deed3ebSAl Viro break; 13989deed3ebSAl Viro 13999deed3ebSAl Viro // uncovered automount point 14009deed3ebSAl Viro ret = follow_automount(path, count, lookup_flags); 14019deed3ebSAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 14029875cf80SDavid Howells if (ret < 0) 14038aef1884SAl Viro break; 14049875cf80SDavid Howells } 14059875cf80SDavid Howells 14069deed3ebSAl Viro if (ret == -EISDIR) 14079deed3ebSAl Viro ret = 0; 14089deed3ebSAl Viro // possible if you race with several mount --move 14099deed3ebSAl Viro if (need_mntput && path->mnt == mnt) 14108aef1884SAl Viro mntput(path->mnt); 14119deed3ebSAl Viro if (!ret && unlikely(d_flags_negative(flags))) 1412d41efb52SAl Viro ret = -ENOENT; 14139deed3ebSAl Viro *jumped = need_mntput; 14148402752eSAl Viro return ret; 14151da177e4SLinus Torvalds } 14161da177e4SLinus Torvalds 14179deed3ebSAl Viro static inline int traverse_mounts(struct path *path, bool *jumped, 14189deed3ebSAl Viro int *count, unsigned lookup_flags) 14199deed3ebSAl Viro { 14209deed3ebSAl Viro unsigned flags = smp_load_acquire(&path->dentry->d_flags); 14219deed3ebSAl Viro 14229deed3ebSAl Viro /* fastpath */ 14239deed3ebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) { 14249deed3ebSAl Viro *jumped = false; 14259deed3ebSAl Viro if (unlikely(d_flags_negative(flags))) 14269deed3ebSAl Viro return -ENOENT; 14279deed3ebSAl Viro return 0; 14289deed3ebSAl Viro } 14299deed3ebSAl Viro return __traverse_mounts(path, flags, jumped, count, lookup_flags); 14309deed3ebSAl Viro } 14319deed3ebSAl Viro 1432cc53ce53SDavid Howells int follow_down_one(struct path *path) 14331da177e4SLinus Torvalds { 14341da177e4SLinus Torvalds struct vfsmount *mounted; 14351da177e4SLinus Torvalds 14361c755af4SAl Viro mounted = lookup_mnt(path); 14371da177e4SLinus Torvalds if (mounted) { 14389393bd07SAl Viro dput(path->dentry); 14399393bd07SAl Viro mntput(path->mnt); 14409393bd07SAl Viro path->mnt = mounted; 14419393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 14421da177e4SLinus Torvalds return 1; 14431da177e4SLinus Torvalds } 14441da177e4SLinus Torvalds return 0; 14451da177e4SLinus Torvalds } 14464d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 14471da177e4SLinus Torvalds 14489875cf80SDavid Howells /* 14499deed3ebSAl Viro * Follow down to the covering mount currently visible to userspace. At each 14509deed3ebSAl Viro * point, the filesystem owning that dentry may be queried as to whether the 14519deed3ebSAl Viro * caller is permitted to proceed or not. 14529deed3ebSAl Viro */ 14539deed3ebSAl Viro int follow_down(struct path *path) 14549deed3ebSAl Viro { 14559deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 14569deed3ebSAl Viro bool jumped; 14579deed3ebSAl Viro int ret = traverse_mounts(path, &jumped, NULL, 0); 14589deed3ebSAl Viro 14599deed3ebSAl Viro if (path->mnt != mnt) 14609deed3ebSAl Viro mntput(mnt); 14619deed3ebSAl Viro return ret; 14629deed3ebSAl Viro } 14639deed3ebSAl Viro EXPORT_SYMBOL(follow_down); 14649deed3ebSAl Viro 14659deed3ebSAl Viro /* 1466287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1467287548e4SAl Viro * we meet a managed dentry that would need blocking. 14689875cf80SDavid Howells */ 14699875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1470254cf582SAl Viro struct inode **inode, unsigned *seqp) 14719875cf80SDavid Howells { 1472ea936aebSAl Viro struct dentry *dentry = path->dentry; 1473ea936aebSAl Viro unsigned int flags = dentry->d_flags; 1474ea936aebSAl Viro 1475ea936aebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) 1476ea936aebSAl Viro return true; 1477ea936aebSAl Viro 1478ea936aebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1479ea936aebSAl Viro return false; 1480ea936aebSAl Viro 148162a7375eSIan Kent for (;;) { 148262a7375eSIan Kent /* 148362a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 148462a7375eSIan Kent * that wants to block transit. 148562a7375eSIan Kent */ 1486ea936aebSAl Viro if (unlikely(flags & DCACHE_MANAGE_TRANSIT)) { 1487ea936aebSAl Viro int res = dentry->d_op->d_manage(path, true); 1488ea936aebSAl Viro if (res) 1489ea936aebSAl Viro return res == -EISDIR; 1490ea936aebSAl Viro flags = dentry->d_flags; 1491b8faf035SNeilBrown } 149262a7375eSIan Kent 1493ea936aebSAl Viro if (flags & DCACHE_MOUNTED) { 1494ea936aebSAl Viro struct mount *mounted = __lookup_mnt(path->mnt, dentry); 1495ea936aebSAl Viro if (mounted) { 1496c7105365SAl Viro path->mnt = &mounted->mnt; 1497ea936aebSAl Viro dentry = path->dentry = mounted->mnt.mnt_root; 1498bcba1e7dSAl Viro nd->state |= ND_JUMPED; 1499ea936aebSAl Viro *seqp = read_seqcount_begin(&dentry->d_seq); 1500ea936aebSAl Viro *inode = dentry->d_inode; 150159430262SLinus Torvalds /* 1502ea936aebSAl Viro * We don't need to re-check ->d_seq after this 1503ea936aebSAl Viro * ->d_inode read - there will be an RCU delay 1504ea936aebSAl Viro * between mount hash removal and ->mnt_root 1505ea936aebSAl Viro * becoming unpinned. 150659430262SLinus Torvalds */ 1507ea936aebSAl Viro flags = dentry->d_flags; 150820aac6c6SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 150920aac6c6SAl Viro return false; 1510ea936aebSAl Viro continue; 15119875cf80SDavid Howells } 1512ea936aebSAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1513ea936aebSAl Viro return false; 1514ea936aebSAl Viro } 1515ea936aebSAl Viro return !(flags & DCACHE_NEED_AUTOMOUNT); 1516ea936aebSAl Viro } 1517287548e4SAl Viro } 1518287548e4SAl Viro 1519db3c9adeSAl Viro static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, 1520db3c9adeSAl Viro struct path *path, struct inode **inode, 1521db3c9adeSAl Viro unsigned int *seqp) 1522bd7c4b50SAl Viro { 15239deed3ebSAl Viro bool jumped; 1524db3c9adeSAl Viro int ret; 1525bd7c4b50SAl Viro 1526db3c9adeSAl Viro path->mnt = nd->path.mnt; 1527db3c9adeSAl Viro path->dentry = dentry; 1528c153007bSAl Viro if (nd->flags & LOOKUP_RCU) { 1529c153007bSAl Viro unsigned int seq = *seqp; 1530c153007bSAl Viro if (unlikely(!*inode)) 1531c153007bSAl Viro return -ENOENT; 1532c153007bSAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 15339deed3ebSAl Viro return 0; 1534ae66db45SAl Viro if (!try_to_unlazy_next(nd, dentry, seq)) 1535c153007bSAl Viro return -ECHILD; 1536c153007bSAl Viro // *path might've been clobbered by __follow_mount_rcu() 1537c153007bSAl Viro path->mnt = nd->path.mnt; 1538c153007bSAl Viro path->dentry = dentry; 1539c153007bSAl Viro } 15409deed3ebSAl Viro ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags); 15419deed3ebSAl Viro if (jumped) { 15429deed3ebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 15439deed3ebSAl Viro ret = -EXDEV; 15449deed3ebSAl Viro else 1545bcba1e7dSAl Viro nd->state |= ND_JUMPED; 15469deed3ebSAl Viro } 15479deed3ebSAl Viro if (unlikely(ret)) { 15489deed3ebSAl Viro dput(path->dentry); 15499deed3ebSAl Viro if (path->mnt != nd->path.mnt) 15509deed3ebSAl Viro mntput(path->mnt); 15519deed3ebSAl Viro } else { 1552bd7c4b50SAl Viro *inode = d_backing_inode(path->dentry); 1553bd7c4b50SAl Viro *seqp = 0; /* out of RCU mode, so the value doesn't matter */ 1554bd7c4b50SAl Viro } 1555bd7c4b50SAl Viro return ret; 1556bd7c4b50SAl Viro } 1557bd7c4b50SAl Viro 15589875cf80SDavid Howells /* 1559f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1560f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1561baa03890SNick Piggin */ 1562e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1563e3c13928SAl Viro struct dentry *dir, 15646c51e513SAl Viro unsigned int flags) 1565baa03890SNick Piggin { 1566a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1567bad61189SMiklos Szeredi if (dentry) { 1568a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1569bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 157074ff0ffcSAl Viro if (!error) 15715542aa2fSEric W. Biederman d_invalidate(dentry); 1572bad61189SMiklos Szeredi dput(dentry); 157374ff0ffcSAl Viro return ERR_PTR(error); 1574bad61189SMiklos Szeredi } 1575bad61189SMiklos Szeredi } 1576baa03890SNick Piggin return dentry; 1577baa03890SNick Piggin } 1578baa03890SNick Piggin 1579baa03890SNick Piggin /* 1580a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1581a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1582a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1583a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1584a03ece5fSAl Viro * at all. 158544396f4bSJosef Bacik */ 1586a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1587a03ece5fSAl Viro struct dentry *base, unsigned int flags) 158844396f4bSJosef Bacik { 1589a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 159044396f4bSJosef Bacik struct dentry *old; 1591a03ece5fSAl Viro struct inode *dir = base->d_inode; 1592a03ece5fSAl Viro 1593a03ece5fSAl Viro if (dentry) 1594a03ece5fSAl Viro return dentry; 159544396f4bSJosef Bacik 159644396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1597a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 159844396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1599a03ece5fSAl Viro 1600a03ece5fSAl Viro dentry = d_alloc(base, name); 1601a03ece5fSAl Viro if (unlikely(!dentry)) 1602a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 160344396f4bSJosef Bacik 160472bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 160544396f4bSJosef Bacik if (unlikely(old)) { 160644396f4bSJosef Bacik dput(dentry); 160744396f4bSJosef Bacik dentry = old; 160844396f4bSJosef Bacik } 160944396f4bSJosef Bacik return dentry; 161044396f4bSJosef Bacik } 161144396f4bSJosef Bacik 161220e34357SAl Viro static struct dentry *lookup_fast(struct nameidata *nd, 161320e34357SAl Viro struct inode **inode, 1614254cf582SAl Viro unsigned *seqp) 16151da177e4SLinus Torvalds { 161631e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 16175a18fff2SAl Viro int status = 1; 16189875cf80SDavid Howells 16193cac260aSAl Viro /* 1620b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 16215d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 16225d0f49c1SAl Viro * going to fall back to non-racy lookup. 1623b04f784eSNick Piggin */ 162431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 162531e6b01fSNick Piggin unsigned seq; 1626da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 16275d0f49c1SAl Viro if (unlikely(!dentry)) { 1628e36cffedSJens Axboe if (!try_to_unlazy(nd)) 162920e34357SAl Viro return ERR_PTR(-ECHILD); 163020e34357SAl Viro return NULL; 16315d0f49c1SAl Viro } 16325a18fff2SAl Viro 163312f8ad4bSLinus Torvalds /* 163412f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 163512f8ad4bSLinus Torvalds * the dentry name information from lookup. 163612f8ad4bSLinus Torvalds */ 163763afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1638*82ef0698SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 163920e34357SAl Viro return ERR_PTR(-ECHILD); 164012f8ad4bSLinus Torvalds 164112f8ad4bSLinus Torvalds /* 164212f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 164312f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 164412f8ad4bSLinus Torvalds * 164512f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 164612f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 164712f8ad4bSLinus Torvalds */ 1648*82ef0698SAl Viro if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 164920e34357SAl Viro return ERR_PTR(-ECHILD); 16505a18fff2SAl Viro 1651254cf582SAl Viro *seqp = seq; 16524ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1653c153007bSAl Viro if (likely(status > 0)) 165420e34357SAl Viro return dentry; 1655ae66db45SAl Viro if (!try_to_unlazy_next(nd, dentry, seq)) 165620e34357SAl Viro return ERR_PTR(-ECHILD); 165726ddb45eSSteven Rostedt (VMware) if (status == -ECHILD) 1658209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1659209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 16605a18fff2SAl Viro } else { 1661e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 166281e6f520SAl Viro if (unlikely(!dentry)) 166320e34357SAl Viro return NULL; 16644ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16655d0f49c1SAl Viro } 16665a18fff2SAl Viro if (unlikely(status <= 0)) { 1667e9742b53SAl Viro if (!status) 16685d0f49c1SAl Viro d_invalidate(dentry); 16695a18fff2SAl Viro dput(dentry); 167020e34357SAl Viro return ERR_PTR(status); 16715a18fff2SAl Viro } 167220e34357SAl Viro return dentry; 1673697f514dSMiklos Szeredi } 1674697f514dSMiklos Szeredi 1675697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 167688d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1677e3c13928SAl Viro struct dentry *dir, 1678e3c13928SAl Viro unsigned int flags) 1679697f514dSMiklos Szeredi { 168088d8331aSAl Viro struct dentry *dentry, *old; 16811936386eSAl Viro struct inode *inode = dir->d_inode; 1682d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16831936386eSAl Viro 16841936386eSAl Viro /* Don't go there if it's already dead */ 168594bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 168688d8331aSAl Viro return ERR_PTR(-ENOENT); 168794bdd655SAl Viro again: 1688d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 168994bdd655SAl Viro if (IS_ERR(dentry)) 169088d8331aSAl Viro return dentry; 169194bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1692949a852eSAl Viro int error = d_revalidate(dentry, flags); 1693949a852eSAl Viro if (unlikely(error <= 0)) { 169494bdd655SAl Viro if (!error) { 1695949a852eSAl Viro d_invalidate(dentry); 1696949a852eSAl Viro dput(dentry); 169794bdd655SAl Viro goto again; 169894bdd655SAl Viro } 169994bdd655SAl Viro dput(dentry); 1700949a852eSAl Viro dentry = ERR_PTR(error); 1701949a852eSAl Viro } 170294bdd655SAl Viro } else { 17031936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 170485c7f810SAl Viro d_lookup_done(dentry); 17051936386eSAl Viro if (unlikely(old)) { 17061936386eSAl Viro dput(dentry); 17071936386eSAl Viro dentry = old; 1708949a852eSAl Viro } 1709949a852eSAl Viro } 1710e3c13928SAl Viro return dentry; 17111da177e4SLinus Torvalds } 17121da177e4SLinus Torvalds 171388d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 171488d8331aSAl Viro struct dentry *dir, 171588d8331aSAl Viro unsigned int flags) 171688d8331aSAl Viro { 171788d8331aSAl Viro struct inode *inode = dir->d_inode; 171888d8331aSAl Viro struct dentry *res; 171988d8331aSAl Viro inode_lock_shared(inode); 172088d8331aSAl Viro res = __lookup_slow(name, dir, flags); 172188d8331aSAl Viro inode_unlock_shared(inode); 172288d8331aSAl Viro return res; 172388d8331aSAl Viro } 172488d8331aSAl Viro 1725ba73d987SChristian Brauner static inline int may_lookup(struct user_namespace *mnt_userns, 1726ba73d987SChristian Brauner struct nameidata *nd) 172752094c8aSAl Viro { 172852094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 17297d6beb71SLinus Torvalds int err = inode_permission(mnt_userns, nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 1730e36cffedSJens Axboe if (err != -ECHILD || !try_to_unlazy(nd)) 173152094c8aSAl Viro return err; 173252094c8aSAl Viro } 1733ba73d987SChristian Brauner return inode_permission(mnt_userns, nd->inode, MAY_EXEC); 173452094c8aSAl Viro } 173552094c8aSAl Viro 173649055906SAl Viro static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq) 1737d63ff28fSAl Viro { 173849055906SAl Viro if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) 173949055906SAl Viro return -ELOOP; 17404542576bSAl Viro 17414542576bSAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 17424542576bSAl Viro return 0; 17434542576bSAl Viro if (likely(nd->stack != nd->internal)) 17444542576bSAl Viro return 0; 174560ef60c7SAl Viro if (likely(nd_alloc_stack(nd))) 174649055906SAl Viro return 0; 174760ef60c7SAl Viro 174860ef60c7SAl Viro if (nd->flags & LOOKUP_RCU) { 174960ef60c7SAl Viro // we need to grab link before we do unlazy. And we can't skip 175060ef60c7SAl Viro // unlazy even if we fail to grab the link - cleanup needs it 1751aef9404dSAl Viro bool grabbed_link = legitimize_path(nd, link, seq); 175260ef60c7SAl Viro 1753e5ca024eSAl Viro if (!try_to_unlazy(nd) || !grabbed_link) 175460ef60c7SAl Viro return -ECHILD; 175560ef60c7SAl Viro 175660ef60c7SAl Viro if (nd_alloc_stack(nd)) 175760ef60c7SAl Viro return 0; 1758bc40aee0SAl Viro } 175960ef60c7SAl Viro return -ENOMEM; 176049055906SAl Viro } 176149055906SAl Viro 176249055906SAl Viro enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 176349055906SAl Viro 176449055906SAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 176549055906SAl Viro struct inode *inode, unsigned seq, int flags) 176649055906SAl Viro { 176749055906SAl Viro struct saved *last; 176849055906SAl Viro const char *res; 176949055906SAl Viro int error = reserve_stack(nd, link, seq); 177049055906SAl Viro 177149055906SAl Viro if (unlikely(error)) { 177249055906SAl Viro if (!(nd->flags & LOOKUP_RCU)) 1773cd179f44SAl Viro path_put(link); 177406708adbSAl Viro return ERR_PTR(error); 1775626de996SAl Viro } 1776ab104923SAl Viro last = nd->stack + nd->depth++; 17771cf2665bSAl Viro last->link = *link; 1778fceef393SAl Viro clear_delayed_call(&last->done); 17790450b2d1SAl Viro last->seq = seq; 1780ad6cc4c3SAl Viro 1781b1a81972SAl Viro if (flags & WALK_TRAILING) { 1782ad6cc4c3SAl Viro error = may_follow_link(nd, inode); 1783ad6cc4c3SAl Viro if (unlikely(error)) 1784ad6cc4c3SAl Viro return ERR_PTR(error); 1785ad6cc4c3SAl Viro } 1786ad6cc4c3SAl Viro 1787dab741e0SMattias Nissler if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS) || 1788dab741e0SMattias Nissler unlikely(link->mnt->mnt_flags & MNT_NOSYMFOLLOW)) 1789ad6cc4c3SAl Viro return ERR_PTR(-ELOOP); 1790ad6cc4c3SAl Viro 1791ad6cc4c3SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1792ad6cc4c3SAl Viro touch_atime(&last->link); 1793ad6cc4c3SAl Viro cond_resched(); 1794ad6cc4c3SAl Viro } else if (atime_needs_update(&last->link, inode)) { 1795e36cffedSJens Axboe if (!try_to_unlazy(nd)) 1796ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1797ad6cc4c3SAl Viro touch_atime(&last->link); 1798ad6cc4c3SAl Viro } 1799ad6cc4c3SAl Viro 1800ad6cc4c3SAl Viro error = security_inode_follow_link(link->dentry, inode, 1801ad6cc4c3SAl Viro nd->flags & LOOKUP_RCU); 1802ad6cc4c3SAl Viro if (unlikely(error)) 1803ad6cc4c3SAl Viro return ERR_PTR(error); 1804ad6cc4c3SAl Viro 1805ad6cc4c3SAl Viro res = READ_ONCE(inode->i_link); 1806ad6cc4c3SAl Viro if (!res) { 1807ad6cc4c3SAl Viro const char * (*get)(struct dentry *, struct inode *, 1808ad6cc4c3SAl Viro struct delayed_call *); 1809ad6cc4c3SAl Viro get = inode->i_op->get_link; 1810ad6cc4c3SAl Viro if (nd->flags & LOOKUP_RCU) { 1811ad6cc4c3SAl Viro res = get(NULL, inode, &last->done); 1812e36cffedSJens Axboe if (res == ERR_PTR(-ECHILD) && try_to_unlazy(nd)) 1813ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1814ad6cc4c3SAl Viro } else { 1815ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1816ad6cc4c3SAl Viro } 1817ad6cc4c3SAl Viro if (!res) 1818ad6cc4c3SAl Viro goto all_done; 1819ad6cc4c3SAl Viro if (IS_ERR(res)) 1820ad6cc4c3SAl Viro return res; 1821ad6cc4c3SAl Viro } 1822ad6cc4c3SAl Viro if (*res == '/') { 1823ad6cc4c3SAl Viro error = nd_jump_root(nd); 1824ad6cc4c3SAl Viro if (unlikely(error)) 1825ad6cc4c3SAl Viro return ERR_PTR(error); 1826ad6cc4c3SAl Viro while (unlikely(*++res == '/')) 1827ad6cc4c3SAl Viro ; 1828ad6cc4c3SAl Viro } 1829ad6cc4c3SAl Viro if (*res) 1830ad6cc4c3SAl Viro return res; 1831ad6cc4c3SAl Viro all_done: // pure jump 1832ad6cc4c3SAl Viro put_link(nd); 1833ad6cc4c3SAl Viro return NULL; 1834d63ff28fSAl Viro } 1835d63ff28fSAl Viro 18363ddcd056SLinus Torvalds /* 18373ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 18383ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 18393ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 18403ddcd056SLinus Torvalds * for the common case. 18413ddcd056SLinus Torvalds */ 1842b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1843cbae4d12SAl Viro struct dentry *dentry, struct inode *inode, unsigned seq) 18443ddcd056SLinus Torvalds { 1845cbae4d12SAl Viro struct path path; 1846cbae4d12SAl Viro int err = handle_mounts(nd, dentry, &path, &inode, &seq); 1847cbae4d12SAl Viro 1848cbae4d12SAl Viro if (err < 0) 1849b0417d2cSAl Viro return ERR_PTR(err); 1850cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 18518c4efe22SAl Viro ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) || 1852aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 18538f64fb1cSAl Viro /* not a symlink or should not follow */ 1854c99687a0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1855c99687a0SAl Viro dput(nd->path.dentry); 1856c99687a0SAl Viro if (nd->path.mnt != path.mnt) 1857c99687a0SAl Viro mntput(nd->path.mnt); 1858c99687a0SAl Viro } 1859c99687a0SAl Viro nd->path = path; 18608f64fb1cSAl Viro nd->inode = inode; 18618f64fb1cSAl Viro nd->seq = seq; 1862b0417d2cSAl Viro return NULL; 18638f64fb1cSAl Viro } 1864a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 186584f0cd9eSAl Viro /* make sure that d_is_symlink above matches inode */ 1866cbae4d12SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, seq)) 1867b0417d2cSAl Viro return ERR_PTR(-ECHILD); 186884f0cd9eSAl Viro } else { 186984f0cd9eSAl Viro if (path.mnt == nd->path.mnt) 187084f0cd9eSAl Viro mntget(path.mnt); 1871a7f77542SAl Viro } 1872b1a81972SAl Viro return pick_link(nd, &path, inode, seq, flags); 18733ddcd056SLinus Torvalds } 18743ddcd056SLinus Torvalds 1875c2df1968SAl Viro static struct dentry *follow_dotdot_rcu(struct nameidata *nd, 1876c2df1968SAl Viro struct inode **inodep, 1877c2df1968SAl Viro unsigned *seqp) 1878957dd41dSAl Viro { 187912487f30SAl Viro struct dentry *parent, *old; 1880957dd41dSAl Viro 188112487f30SAl Viro if (path_equal(&nd->path, &nd->root)) 188212487f30SAl Viro goto in_root; 188312487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 18847ef482faSAl Viro struct path path; 1885efe772d6SAl Viro unsigned seq; 18867ef482faSAl Viro if (!choose_mountpoint_rcu(real_mount(nd->path.mnt), 18877ef482faSAl Viro &nd->root, &path, &seq)) 188812487f30SAl Viro goto in_root; 1889efe772d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1890efe772d6SAl Viro return ERR_PTR(-ECHILD); 1891efe772d6SAl Viro nd->path = path; 1892efe772d6SAl Viro nd->inode = path.dentry->d_inode; 1893efe772d6SAl Viro nd->seq = seq; 1894*82ef0698SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1895efe772d6SAl Viro return ERR_PTR(-ECHILD); 1896efe772d6SAl Viro /* we know that mountpoint was pinned */ 1897957dd41dSAl Viro } 189812487f30SAl Viro old = nd->path.dentry; 189912487f30SAl Viro parent = old->d_parent; 190012487f30SAl Viro *inodep = parent->d_inode; 190112487f30SAl Viro *seqp = read_seqcount_begin(&parent->d_seq); 1902*82ef0698SAl Viro if (read_seqcount_retry(&old->d_seq, nd->seq)) 190312487f30SAl Viro return ERR_PTR(-ECHILD); 190412487f30SAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) 190512487f30SAl Viro return ERR_PTR(-ECHILD); 190612487f30SAl Viro return parent; 190712487f30SAl Viro in_root: 1908*82ef0698SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1909efe772d6SAl Viro return ERR_PTR(-ECHILD); 1910957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 19117521f22bSAl Viro return ERR_PTR(-ECHILD); 1912c2df1968SAl Viro return NULL; 1913957dd41dSAl Viro } 1914957dd41dSAl Viro 1915c2df1968SAl Viro static struct dentry *follow_dotdot(struct nameidata *nd, 1916c2df1968SAl Viro struct inode **inodep, 1917c2df1968SAl Viro unsigned *seqp) 1918957dd41dSAl Viro { 191912487f30SAl Viro struct dentry *parent; 192012487f30SAl Viro 1921957dd41dSAl Viro if (path_equal(&nd->path, &nd->root)) 192212487f30SAl Viro goto in_root; 192312487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 19242aa38470SAl Viro struct path path; 19252aa38470SAl Viro 19262aa38470SAl Viro if (!choose_mountpoint(real_mount(nd->path.mnt), 19272aa38470SAl Viro &nd->root, &path)) 192812487f30SAl Viro goto in_root; 1929165200d6SAl Viro path_put(&nd->path); 1930165200d6SAl Viro nd->path = path; 19312aa38470SAl Viro nd->inode = path.dentry->d_inode; 1932165200d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1933165200d6SAl Viro return ERR_PTR(-EXDEV); 193412487f30SAl Viro } 1935957dd41dSAl Viro /* rare case of legitimate dget_parent()... */ 193612487f30SAl Viro parent = dget_parent(nd->path.dentry); 1937957dd41dSAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) { 1938957dd41dSAl Viro dput(parent); 19397521f22bSAl Viro return ERR_PTR(-ENOENT); 1940957dd41dSAl Viro } 1941c2df1968SAl Viro *seqp = 0; 1942c2df1968SAl Viro *inodep = parent->d_inode; 1943c2df1968SAl Viro return parent; 194412487f30SAl Viro 194512487f30SAl Viro in_root: 1946957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 19477521f22bSAl Viro return ERR_PTR(-EXDEV); 1948c2df1968SAl Viro dget(nd->path.dentry); 1949c2df1968SAl Viro return NULL; 1950957dd41dSAl Viro } 1951957dd41dSAl Viro 19527521f22bSAl Viro static const char *handle_dots(struct nameidata *nd, int type) 1953957dd41dSAl Viro { 1954957dd41dSAl Viro if (type == LAST_DOTDOT) { 19557521f22bSAl Viro const char *error = NULL; 1956c2df1968SAl Viro struct dentry *parent; 1957c2df1968SAl Viro struct inode *inode; 1958c2df1968SAl Viro unsigned seq; 1959957dd41dSAl Viro 1960957dd41dSAl Viro if (!nd->root.mnt) { 19617521f22bSAl Viro error = ERR_PTR(set_root(nd)); 1962957dd41dSAl Viro if (error) 1963957dd41dSAl Viro return error; 1964957dd41dSAl Viro } 1965957dd41dSAl Viro if (nd->flags & LOOKUP_RCU) 1966c2df1968SAl Viro parent = follow_dotdot_rcu(nd, &inode, &seq); 1967957dd41dSAl Viro else 1968c2df1968SAl Viro parent = follow_dotdot(nd, &inode, &seq); 1969c2df1968SAl Viro if (IS_ERR(parent)) 1970c2df1968SAl Viro return ERR_CAST(parent); 1971c2df1968SAl Viro if (unlikely(!parent)) 1972c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1973c2df1968SAl Viro nd->path.dentry, nd->inode, nd->seq); 1974c2df1968SAl Viro else 1975c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1976c2df1968SAl Viro parent, inode, seq); 1977c2df1968SAl Viro if (unlikely(error)) 1978957dd41dSAl Viro return error; 1979957dd41dSAl Viro 1980957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1981957dd41dSAl Viro /* 1982957dd41dSAl Viro * If there was a racing rename or mount along our 1983957dd41dSAl Viro * path, then we can't be sure that ".." hasn't jumped 1984957dd41dSAl Viro * above nd->root (and so userspace should retry or use 1985957dd41dSAl Viro * some fallback). 1986957dd41dSAl Viro */ 1987957dd41dSAl Viro smp_rmb(); 1988*82ef0698SAl Viro if (__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq)) 19897521f22bSAl Viro return ERR_PTR(-EAGAIN); 1990*82ef0698SAl Viro if (__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq)) 19917521f22bSAl Viro return ERR_PTR(-EAGAIN); 1992957dd41dSAl Viro } 1993957dd41dSAl Viro } 19947521f22bSAl Viro return NULL; 1995957dd41dSAl Viro } 1996957dd41dSAl Viro 199792d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1998ce57dfc1SAl Viro { 1999db3c9adeSAl Viro struct dentry *dentry; 2000ce57dfc1SAl Viro struct inode *inode; 2001254cf582SAl Viro unsigned seq; 2002ce57dfc1SAl Viro /* 2003ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 2004ce57dfc1SAl Viro * to be able to know about the current root directory and 2005ce57dfc1SAl Viro * parent relationships. 2006ce57dfc1SAl Viro */ 20074693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 20081c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 20094693a547SAl Viro put_link(nd); 20107521f22bSAl Viro return handle_dots(nd, nd->last_type); 20114693a547SAl Viro } 201220e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 201320e34357SAl Viro if (IS_ERR(dentry)) 201492d27016SAl Viro return ERR_CAST(dentry); 201520e34357SAl Viro if (unlikely(!dentry)) { 2016db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 2017db3c9adeSAl Viro if (IS_ERR(dentry)) 201892d27016SAl Viro return ERR_CAST(dentry); 201920e34357SAl Viro } 202056676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 202156676ec3SAl Viro put_link(nd); 2022b0417d2cSAl Viro return step_into(nd, flags, dentry, inode, seq); 2023ce57dfc1SAl Viro } 2024ce57dfc1SAl Viro 20251da177e4SLinus Torvalds /* 2026bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 2027bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 2028bfcfaa77SLinus Torvalds * 2029bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 2030bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 2031bfcfaa77SLinus Torvalds * fast. 2032bfcfaa77SLinus Torvalds * 2033bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 2034bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 2035bfcfaa77SLinus Torvalds * crossing operation. 2036bfcfaa77SLinus Torvalds * 2037bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 2038bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 2039bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 2040bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 2041bfcfaa77SLinus Torvalds */ 2042bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 2043bfcfaa77SLinus Torvalds 2044f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 2045bfcfaa77SLinus Torvalds 2046468a9428SGeorge Spelvin #ifdef HASH_MIX 2047bfcfaa77SLinus Torvalds 2048468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 2049468a9428SGeorge Spelvin 2050468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 20512a18da7aSGeorge Spelvin /* 20522a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 20532a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 20542a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 20552a18da7aSGeorge Spelvin * and no temporaries. 20562a18da7aSGeorge Spelvin * 20572a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 20582a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 20592a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 20602a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 20612a18da7aSGeorge Spelvin * 20622a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 20632a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 20642a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 20652a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 20662a18da7aSGeorge Spelvin * 20672a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 20682a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 20692a18da7aSGeorge Spelvin * toggling any given output bit. 20702a18da7aSGeorge Spelvin * 20712a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 20722a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 20732a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 20742a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 20752a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 20762a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 20772a18da7aSGeorge Spelvin * Perfect: 8192 258048 20782a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 20792a18da7aSGeorge Spelvin */ 20802a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 20812a18da7aSGeorge Spelvin ( x ^= (a), \ 20822a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 20832a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 20842a18da7aSGeorge Spelvin y *= 9 ) 2085bfcfaa77SLinus Torvalds 20860fed3ac8SGeorge Spelvin /* 20872a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 20882a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 20892a18da7aSGeorge Spelvin * work done before the hash value is used. 20900fed3ac8SGeorge Spelvin */ 20912a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 20920fed3ac8SGeorge Spelvin { 20932a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 20942a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 20952a18da7aSGeorge Spelvin return y >> 32; 20960fed3ac8SGeorge Spelvin } 20970fed3ac8SGeorge Spelvin 2098bfcfaa77SLinus Torvalds #else /* 32-bit case */ 2099bfcfaa77SLinus Torvalds 21002a18da7aSGeorge Spelvin /* 21012a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 21022a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 21032a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 21042a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 21052a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 21062a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 21072a18da7aSGeorge Spelvin * Perfect: 2048 31744 21082a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 21092a18da7aSGeorge Spelvin */ 21102a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 21112a18da7aSGeorge Spelvin ( x ^= (a), \ 21122a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 21132a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 21142a18da7aSGeorge Spelvin y *= 9 ) 2115bfcfaa77SLinus Torvalds 21162a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 21170fed3ac8SGeorge Spelvin { 21182a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 21192a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 21200fed3ac8SGeorge Spelvin } 21210fed3ac8SGeorge Spelvin 2122bfcfaa77SLinus Torvalds #endif 2123bfcfaa77SLinus Torvalds 21242a18da7aSGeorge Spelvin /* 21252a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 21262a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 21272a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 21282a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 21292a18da7aSGeorge Spelvin * finds the delimiter after the name. 21302a18da7aSGeorge Spelvin */ 21318387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 2132bfcfaa77SLinus Torvalds { 21338387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 2134bfcfaa77SLinus Torvalds 2135bfcfaa77SLinus Torvalds for (;;) { 2136fcfd2fbfSGeorge Spelvin if (!len) 2137fcfd2fbfSGeorge Spelvin goto done; 2138e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 2139bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 2140bfcfaa77SLinus Torvalds break; 21412a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2142bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 2143bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 2144bfcfaa77SLinus Torvalds } 21452a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 2146bfcfaa77SLinus Torvalds done: 21472a18da7aSGeorge Spelvin return fold_hash(x, y); 2148bfcfaa77SLinus Torvalds } 2149bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 2150bfcfaa77SLinus Torvalds 2151fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 21528387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2153fcfd2fbfSGeorge Spelvin { 21548387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 21558387ff25SLinus Torvalds unsigned long adata, mask, len; 2156fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2157fcfd2fbfSGeorge Spelvin 21588387ff25SLinus Torvalds len = 0; 21598387ff25SLinus Torvalds goto inside; 21608387ff25SLinus Torvalds 2161fcfd2fbfSGeorge Spelvin do { 21622a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2163fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 21648387ff25SLinus Torvalds inside: 2165fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2166fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2167fcfd2fbfSGeorge Spelvin 2168fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2169fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 21702a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2171fcfd2fbfSGeorge Spelvin 21722a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2173fcfd2fbfSGeorge Spelvin } 2174fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2175fcfd2fbfSGeorge Spelvin 2176bfcfaa77SLinus Torvalds /* 2177bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2178d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2179bfcfaa77SLinus Torvalds */ 21808387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2181bfcfaa77SLinus Torvalds { 21828387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 21838387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 218436126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2185bfcfaa77SLinus Torvalds 21868387ff25SLinus Torvalds len = 0; 21878387ff25SLinus Torvalds goto inside; 21888387ff25SLinus Torvalds 2189bfcfaa77SLinus Torvalds do { 21902a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2191bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 21928387ff25SLinus Torvalds inside: 2193e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 219436126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 219536126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2196bfcfaa77SLinus Torvalds 219736126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 219836126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 219936126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 22002a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 220136126f8fSLinus Torvalds 22022a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2203bfcfaa77SLinus Torvalds } 2204bfcfaa77SLinus Torvalds 22052a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2206bfcfaa77SLinus Torvalds 2207fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 22088387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 22090145acc2SLinus Torvalds { 22108387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 22110145acc2SLinus Torvalds while (len--) 2212fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 22130145acc2SLinus Torvalds return end_name_hash(hash); 22140145acc2SLinus Torvalds } 2215ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 22160145acc2SLinus Torvalds 2217fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 22188387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2219fcfd2fbfSGeorge Spelvin { 22208387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2221fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2222fcfd2fbfSGeorge Spelvin 2223fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2224e0ab7af9SGeorge Spelvin while (c) { 2225fcfd2fbfSGeorge Spelvin len++; 2226fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2227fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2228e0ab7af9SGeorge Spelvin } 2229fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2230fcfd2fbfSGeorge Spelvin } 2231f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2232fcfd2fbfSGeorge Spelvin 22333ddcd056SLinus Torvalds /* 2234200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2235200e9ef7SLinus Torvalds * one character. 2236200e9ef7SLinus Torvalds */ 22378387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2238200e9ef7SLinus Torvalds { 22398387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2240200e9ef7SLinus Torvalds unsigned long len = 0, c; 2241200e9ef7SLinus Torvalds 2242200e9ef7SLinus Torvalds c = (unsigned char)*name; 2243200e9ef7SLinus Torvalds do { 2244200e9ef7SLinus Torvalds len++; 2245200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2246200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2247200e9ef7SLinus Torvalds } while (c && c != '/'); 2248d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2249200e9ef7SLinus Torvalds } 2250200e9ef7SLinus Torvalds 2251bfcfaa77SLinus Torvalds #endif 2252bfcfaa77SLinus Torvalds 2253200e9ef7SLinus Torvalds /* 22541da177e4SLinus Torvalds * Name resolution. 2255ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2256ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 22571da177e4SLinus Torvalds * 2258ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2259ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 22601da177e4SLinus Torvalds */ 22616de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 22621da177e4SLinus Torvalds { 2263d8d4611aSAl Viro int depth = 0; // depth <= nd->depth 22641da177e4SLinus Torvalds int err; 22651da177e4SLinus Torvalds 2266b4c03536SAl Viro nd->last_type = LAST_ROOT; 2267c108837eSAl Viro nd->flags |= LOOKUP_PARENT; 22689b5858e9SAl Viro if (IS_ERR(name)) 22699b5858e9SAl Viro return PTR_ERR(name); 22701da177e4SLinus Torvalds while (*name=='/') 22711da177e4SLinus Torvalds name++; 22721a97d899SAl Viro if (!*name) { 22731a97d899SAl Viro nd->dir_mode = 0; // short-circuit the 'hardening' idiocy 22749e18f10aSAl Viro return 0; 22751a97d899SAl Viro } 22761da177e4SLinus Torvalds 22771da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 22781da177e4SLinus Torvalds for(;;) { 2279549c7297SChristian Brauner struct user_namespace *mnt_userns; 228092d27016SAl Viro const char *link; 2281d6bb3e90SLinus Torvalds u64 hash_len; 2282fe479a58SAl Viro int type; 22831da177e4SLinus Torvalds 2284549c7297SChristian Brauner mnt_userns = mnt_user_ns(nd->path.mnt); 2285549c7297SChristian Brauner err = may_lookup(mnt_userns, nd); 22861da177e4SLinus Torvalds if (err) 22873595e234SAl Viro return err; 22881da177e4SLinus Torvalds 22898387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 22901da177e4SLinus Torvalds 2291fe479a58SAl Viro type = LAST_NORM; 2292d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2293fe479a58SAl Viro case 2: 2294200e9ef7SLinus Torvalds if (name[1] == '.') { 2295fe479a58SAl Viro type = LAST_DOTDOT; 2296bcba1e7dSAl Viro nd->state |= ND_JUMPED; 229716c2cd71SAl Viro } 2298fe479a58SAl Viro break; 2299fe479a58SAl Viro case 1: 2300fe479a58SAl Viro type = LAST_DOT; 2301fe479a58SAl Viro } 23025a202bcdSAl Viro if (likely(type == LAST_NORM)) { 23035a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 2304bcba1e7dSAl Viro nd->state &= ~ND_JUMPED; 23055a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2306a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2307da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 23085a202bcdSAl Viro if (err < 0) 23093595e234SAl Viro return err; 2310d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2311d6bb3e90SLinus Torvalds name = this.name; 23125a202bcdSAl Viro } 23135a202bcdSAl Viro } 2314fe479a58SAl Viro 2315d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2316d6bb3e90SLinus Torvalds nd->last.name = name; 23175f4a6a69SAl Viro nd->last_type = type; 23185f4a6a69SAl Viro 2319d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2320d6bb3e90SLinus Torvalds if (!*name) 2321bdf6cbf1SAl Viro goto OK; 2322200e9ef7SLinus Torvalds /* 2323200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2324200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2325200e9ef7SLinus Torvalds */ 2326200e9ef7SLinus Torvalds do { 2327d6bb3e90SLinus Torvalds name++; 2328d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 23298620c238SAl Viro if (unlikely(!*name)) { 23308620c238SAl Viro OK: 2331d8d4611aSAl Viro /* pathname or trailing symlink, done */ 2332c108837eSAl Viro if (!depth) { 2333549c7297SChristian Brauner nd->dir_uid = i_uid_into_mnt(mnt_userns, nd->inode); 23340f705953SAl Viro nd->dir_mode = nd->inode->i_mode; 2335c108837eSAl Viro nd->flags &= ~LOOKUP_PARENT; 23368620c238SAl Viro return 0; 2337c108837eSAl Viro } 23388620c238SAl Viro /* last component of nested symlink */ 2339d8d4611aSAl Viro name = nd->stack[--depth].name; 23408c4efe22SAl Viro link = walk_component(nd, 0); 23411c4ff1a8SAl Viro } else { 23421c4ff1a8SAl Viro /* not the last component */ 23438c4efe22SAl Viro link = walk_component(nd, WALK_MORE); 23448620c238SAl Viro } 234592d27016SAl Viro if (unlikely(link)) { 234692d27016SAl Viro if (IS_ERR(link)) 234792d27016SAl Viro return PTR_ERR(link); 234892d27016SAl Viro /* a symlink to follow */ 2349d8d4611aSAl Viro nd->stack[depth++].name = name; 235092d27016SAl Viro name = link; 23519e18f10aSAl Viro continue; 235248c8b0c5SAl Viro } 235397242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 235497242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 2355e36cffedSJens Axboe if (!try_to_unlazy(nd)) 235697242f99SAl Viro return -ECHILD; 235797242f99SAl Viro } 23583595e234SAl Viro return -ENOTDIR; 23595f4a6a69SAl Viro } 2360ce57dfc1SAl Viro } 236197242f99SAl Viro } 23621da177e4SLinus Torvalds 2363edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2364c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 236531e6b01fSNick Piggin { 2366740a1678SAleksa Sarai int error; 2367c8a53ee5SAl Viro const char *s = nd->name->name; 236831e6b01fSNick Piggin 23696c6ec2b0SJens Axboe /* LOOKUP_CACHED requires RCU, ask caller to retry */ 23706c6ec2b0SJens Axboe if ((flags & (LOOKUP_RCU | LOOKUP_CACHED)) == LOOKUP_CACHED) 23716c6ec2b0SJens Axboe return ERR_PTR(-EAGAIN); 23726c6ec2b0SJens Axboe 2373c0eb027eSLinus Torvalds if (!*s) 2374c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2375edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2376edc2b1daSAl Viro rcu_read_lock(); 2377c0eb027eSLinus Torvalds 2378bcba1e7dSAl Viro nd->flags = flags; 2379bcba1e7dSAl Viro nd->state |= ND_JUMPED; 2380ab87f9a5SAleksa Sarai 2381ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2382ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2383ab87f9a5SAleksa Sarai smp_rmb(); 2384ab87f9a5SAleksa Sarai 2385bcba1e7dSAl Viro if (nd->state & ND_ROOT_PRESET) { 2386b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2387b18825a7SDavid Howells struct inode *inode = root->d_inode; 238893893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2389368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 23905b6ca027SAl Viro nd->path = nd->root; 23915b6ca027SAl Viro nd->inode = inode; 23925b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2393ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 23948f47a016SAl Viro nd->root_seq = nd->seq; 23955b6ca027SAl Viro } else { 23965b6ca027SAl Viro path_get(&nd->path); 23975b6ca027SAl Viro } 2398368ee9baSAl Viro return s; 23995b6ca027SAl Viro } 24005b6ca027SAl Viro 240131e6b01fSNick Piggin nd->root.mnt = NULL; 240231e6b01fSNick Piggin 24038db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 24048db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2405740a1678SAleksa Sarai error = nd_jump_root(nd); 2406740a1678SAleksa Sarai if (unlikely(error)) 2407740a1678SAleksa Sarai return ERR_PTR(error); 2408ef55d917SAl Viro return s; 24098db52c7eSAleksa Sarai } 24108db52c7eSAleksa Sarai 24118db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 24128db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2413e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 241431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2415c28cc364SNick Piggin unsigned seq; 241631e6b01fSNick Piggin 2417c28cc364SNick Piggin do { 2418c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 241931e6b01fSNick Piggin nd->path = fs->pwd; 2420ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2421c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2422c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2423e41f7d4eSAl Viro } else { 2424e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2425ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2426e41f7d4eSAl Viro } 242731e6b01fSNick Piggin } else { 2428582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2429c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 243031e6b01fSNick Piggin struct dentry *dentry; 243131e6b01fSNick Piggin 24322903ff01SAl Viro if (!f.file) 2433368ee9baSAl Viro return ERR_PTR(-EBADF); 243431e6b01fSNick Piggin 24352903ff01SAl Viro dentry = f.file->f_path.dentry; 243631e6b01fSNick Piggin 2437edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 24382903ff01SAl Viro fdput(f); 2439368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2440f52e0c11SAl Viro } 24412903ff01SAl Viro 24422903ff01SAl Viro nd->path = f.file->f_path; 2443e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 244434a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 244534a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 24465590ff0dSUlrich Drepper } else { 24472903ff01SAl Viro path_get(&nd->path); 244834a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 24491da177e4SLinus Torvalds } 245034a26b99SAl Viro fdput(f); 2451e41f7d4eSAl Viro } 24528db52c7eSAleksa Sarai 2453adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2454adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2455adb21d2bSAleksa Sarai nd->root = nd->path; 2456adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2457adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2458adb21d2bSAleksa Sarai } else { 2459adb21d2bSAleksa Sarai path_get(&nd->root); 2460bcba1e7dSAl Viro nd->state |= ND_ROOT_GRABBED; 2461adb21d2bSAleksa Sarai } 2462adb21d2bSAleksa Sarai } 2463adb21d2bSAleksa Sarai return s; 24649b4a9b14SAl Viro } 24659b4a9b14SAl Viro 24661ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 246795fa25d9SAl Viro { 2468bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2469bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2470bd92d7feSAl Viro 2471c108837eSAl Viro return walk_component(nd, WALK_TRAILING); 2472bd92d7feSAl Viro } 2473bd92d7feSAl Viro 24744f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 24754f757f3cSAl Viro { 2476c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2477db3c9adeSAl Viro dget(nd->path.dentry); 2478b0417d2cSAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, 2479b0417d2cSAl Viro nd->path.dentry, nd->inode, nd->seq)); 24804f757f3cSAl Viro } 24814f757f3cSAl Viro 24829b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2483c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 24849b4a9b14SAl Viro { 2485c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2486bd92d7feSAl Viro int err; 248731e6b01fSNick Piggin 24889b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 24894f757f3cSAl Viro err = handle_lookup_down(nd); 24905f336e72SAl Viro if (unlikely(err < 0)) 24915f336e72SAl Viro s = ERR_PTR(err); 24924f757f3cSAl Viro } 24934f757f3cSAl Viro 24941ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 24951ccac622SAl Viro (s = lookup_last(nd)) != NULL) 24961ccac622SAl Viro ; 24974f0ed93fSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 24984f0ed93fSAl Viro err = handle_lookup_down(nd); 2499bcba1e7dSAl Viro nd->state &= ~ND_JUMPED; // no d_weak_revalidate(), please... 25004f0ed93fSAl Viro } 25019f1fafeeSAl Viro if (!err) 25029f1fafeeSAl Viro err = complete_walk(nd); 2503bd92d7feSAl Viro 2504deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2505deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2506bd23a539SAl Viro err = -ENOTDIR; 2507625b6d10SAl Viro if (!err) { 2508625b6d10SAl Viro *path = nd->path; 2509625b6d10SAl Viro nd->path.mnt = NULL; 2510625b6d10SAl Viro nd->path.dentry = NULL; 2511625b6d10SAl Viro } 2512deb106c6SAl Viro terminate_walk(nd); 2513bd92d7feSAl Viro return err; 251431e6b01fSNick Piggin } 251531e6b01fSNick Piggin 2516794ebceaSStephen Brennan int filename_lookup(int dfd, struct filename *name, unsigned flags, 25179ad1aaa6SAl Viro struct path *path, struct path *root) 2518873f1eedSJeff Layton { 2519894bc8c4SAl Viro int retval; 25209883d185SAl Viro struct nameidata nd; 2521abc9f5beSAl Viro if (IS_ERR(name)) 2522abc9f5beSAl Viro return PTR_ERR(name); 252306422964SAl Viro set_nameidata(&nd, dfd, name, root); 2524c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2525873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2526c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2527873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2528c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2529873f1eedSJeff Layton 2530873f1eedSJeff Layton if (likely(!retval)) 2531161aff1dSAl Viro audit_inode(name, path->dentry, 2532161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 25339883d185SAl Viro restore_nameidata(); 2534020250f3SDmitry Kadashev return retval; 2535020250f3SDmitry Kadashev } 2536020250f3SDmitry Kadashev 25378bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2538c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2539391172c4SAl Viro struct path *parent) 25408bcb77faSAl Viro { 2541c8a53ee5SAl Viro const char *s = path_init(nd, flags); 25429b5858e9SAl Viro int err = link_path_walk(s, nd); 25438bcb77faSAl Viro if (!err) 25448bcb77faSAl Viro err = complete_walk(nd); 2545391172c4SAl Viro if (!err) { 2546391172c4SAl Viro *parent = nd->path; 2547391172c4SAl Viro nd->path.mnt = NULL; 2548391172c4SAl Viro nd->path.dentry = NULL; 2549391172c4SAl Viro } 2550deb106c6SAl Viro terminate_walk(nd); 25518bcb77faSAl Viro return err; 25528bcb77faSAl Viro } 25538bcb77faSAl Viro 25540766ec82SStephen Brennan /* Note: this does not consume "name" */ 2555c5f563f9SAl Viro static int filename_parentat(int dfd, struct filename *name, 2556391172c4SAl Viro unsigned int flags, struct path *parent, 2557391172c4SAl Viro struct qstr *last, int *type) 25588bcb77faSAl Viro { 25598bcb77faSAl Viro int retval; 25609883d185SAl Viro struct nameidata nd; 25618bcb77faSAl Viro 25625c31b6ceSAl Viro if (IS_ERR(name)) 25630ee50b47SDmitry Kadashev return PTR_ERR(name); 256406422964SAl Viro set_nameidata(&nd, dfd, name, NULL); 2565c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 25668bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2567c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 25688bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2569c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2570391172c4SAl Viro if (likely(!retval)) { 2571391172c4SAl Viro *last = nd.last; 2572391172c4SAl Viro *type = nd.last_type; 2573c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 2574391172c4SAl Viro } 25759883d185SAl Viro restore_nameidata(); 25760ee50b47SDmitry Kadashev return retval; 25770ee50b47SDmitry Kadashev } 25780ee50b47SDmitry Kadashev 257979714f72SAl Viro /* does lookup, returns the object with parent locked */ 25800766ec82SStephen Brennan static struct dentry *__kern_path_locked(struct filename *name, struct path *path) 25815590ff0dSUlrich Drepper { 25825c31b6ceSAl Viro struct dentry *d; 2583391172c4SAl Viro struct qstr last; 25840ee50b47SDmitry Kadashev int type, error; 258551689104SPaul Moore 2586c5f563f9SAl Viro error = filename_parentat(AT_FDCWD, name, 0, path, &last, &type); 25870ee50b47SDmitry Kadashev if (error) 25880ee50b47SDmitry Kadashev return ERR_PTR(error); 25895c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2590391172c4SAl Viro path_put(path); 25915c31b6ceSAl Viro return ERR_PTR(-EINVAL); 259279714f72SAl Viro } 25935955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2594391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 259579714f72SAl Viro if (IS_ERR(d)) { 25965955102cSAl Viro inode_unlock(path->dentry->d_inode); 2597391172c4SAl Viro path_put(path); 259879714f72SAl Viro } 259979714f72SAl Viro return d; 26005590ff0dSUlrich Drepper } 26015590ff0dSUlrich Drepper 26020766ec82SStephen Brennan struct dentry *kern_path_locked(const char *name, struct path *path) 26030766ec82SStephen Brennan { 26040766ec82SStephen Brennan struct filename *filename = getname_kernel(name); 26050766ec82SStephen Brennan struct dentry *res = __kern_path_locked(filename, path); 26060766ec82SStephen Brennan 26070766ec82SStephen Brennan putname(filename); 26080766ec82SStephen Brennan return res; 26090766ec82SStephen Brennan } 26100766ec82SStephen Brennan 2611d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2612d1811465SAl Viro { 2613794ebceaSStephen Brennan struct filename *filename = getname_kernel(name); 2614794ebceaSStephen Brennan int ret = filename_lookup(AT_FDCWD, filename, flags, path, NULL); 2615794ebceaSStephen Brennan 2616794ebceaSStephen Brennan putname(filename); 2617794ebceaSStephen Brennan return ret; 2618794ebceaSStephen Brennan 2619d1811465SAl Viro } 26204d359507SAl Viro EXPORT_SYMBOL(kern_path); 2621d1811465SAl Viro 262216f18200SJosef 'Jeff' Sipek /** 262316f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 262416f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 262516f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 262616f18200SJosef 'Jeff' Sipek * @name: pointer to file name 262716f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2628e0a01249SAl Viro * @path: pointer to struct path to fill 262916f18200SJosef 'Jeff' Sipek */ 263016f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 263116f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2632e0a01249SAl Viro struct path *path) 263316f18200SJosef 'Jeff' Sipek { 2634794ebceaSStephen Brennan struct filename *filename; 26359ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 2636794ebceaSStephen Brennan int ret; 2637794ebceaSStephen Brennan 2638794ebceaSStephen Brennan filename = getname_kernel(name); 26399ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2640794ebceaSStephen Brennan ret = filename_lookup(AT_FDCWD, filename, flags, path, &root); 2641794ebceaSStephen Brennan putname(filename); 2642794ebceaSStephen Brennan return ret; 264316f18200SJosef 'Jeff' Sipek } 26444d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 264516f18200SJosef 'Jeff' Sipek 2646c2fd68b6SChristian Brauner static int lookup_one_common(struct user_namespace *mnt_userns, 2647c2fd68b6SChristian Brauner const char *name, struct dentry *base, int len, 2648c2fd68b6SChristian Brauner struct qstr *this) 26493c95f0dcSAl Viro { 26503c95f0dcSAl Viro this->name = name; 26513c95f0dcSAl Viro this->len = len; 26523c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 26533c95f0dcSAl Viro if (!len) 26543c95f0dcSAl Viro return -EACCES; 26553c95f0dcSAl Viro 26563c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 26573c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 26583c95f0dcSAl Viro return -EACCES; 26593c95f0dcSAl Viro } 26603c95f0dcSAl Viro 26613c95f0dcSAl Viro while (len--) { 26623c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 26633c95f0dcSAl Viro if (c == '/' || c == '\0') 26643c95f0dcSAl Viro return -EACCES; 26653c95f0dcSAl Viro } 26663c95f0dcSAl Viro /* 26673c95f0dcSAl Viro * See if the low-level filesystem might want 26683c95f0dcSAl Viro * to use its own hash.. 26693c95f0dcSAl Viro */ 26703c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 26713c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 26723c95f0dcSAl Viro if (err < 0) 26733c95f0dcSAl Viro return err; 26743c95f0dcSAl Viro } 26753c95f0dcSAl Viro 2676c2fd68b6SChristian Brauner return inode_permission(mnt_userns, base->d_inode, MAY_EXEC); 26773c95f0dcSAl Viro } 26783c95f0dcSAl Viro 2679eead1911SChristoph Hellwig /** 26800da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 26810da0b7fdSDavid Howells * @name: pathname component to lookup 26820da0b7fdSDavid Howells * @base: base directory to lookup from 26830da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 26840da0b7fdSDavid Howells * 26850da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 26860da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 26870da0b7fdSDavid Howells * 26880da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 26890da0b7fdSDavid Howells * not be called by generic code. 26900da0b7fdSDavid Howells * 26910da0b7fdSDavid Howells * The caller must hold base->i_mutex. 26920da0b7fdSDavid Howells */ 26930da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 26940da0b7fdSDavid Howells { 26950da0b7fdSDavid Howells struct qstr this; 26960da0b7fdSDavid Howells int err; 26970da0b7fdSDavid Howells 26980da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 26990da0b7fdSDavid Howells 2700c2fd68b6SChristian Brauner err = lookup_one_common(&init_user_ns, name, base, len, &this); 27010da0b7fdSDavid Howells if (err) 27020da0b7fdSDavid Howells return ERR_PTR(err); 27030da0b7fdSDavid Howells 27040da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 27050da0b7fdSDavid Howells } 27060da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 27070da0b7fdSDavid Howells 27080da0b7fdSDavid Howells /** 2709a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2710eead1911SChristoph Hellwig * @name: pathname component to lookup 2711eead1911SChristoph Hellwig * @base: base directory to lookup from 2712eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2713eead1911SChristoph Hellwig * 2714a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 27159e7543e9SAl Viro * not be called by generic code. 2716bbddca8eSNeilBrown * 2717bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2718eead1911SChristoph Hellwig */ 2719057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2720057f6c01SJames Morris { 27218613a209SAl Viro struct dentry *dentry; 2722057f6c01SJames Morris struct qstr this; 2723cda309deSMiklos Szeredi int err; 2724057f6c01SJames Morris 27255955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 27262f9092e1SDavid Woodhouse 2727c2fd68b6SChristian Brauner err = lookup_one_common(&init_user_ns, name, base, len, &this); 2728cda309deSMiklos Szeredi if (err) 2729cda309deSMiklos Szeredi return ERR_PTR(err); 2730cda309deSMiklos Szeredi 27318613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 27328613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2733057f6c01SJames Morris } 27344d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2735057f6c01SJames Morris 2736bbddca8eSNeilBrown /** 2737c2fd68b6SChristian Brauner * lookup_one - filesystem helper to lookup single pathname component 2738c2fd68b6SChristian Brauner * @mnt_userns: user namespace of the mount the lookup is performed from 2739c2fd68b6SChristian Brauner * @name: pathname component to lookup 2740c2fd68b6SChristian Brauner * @base: base directory to lookup from 2741c2fd68b6SChristian Brauner * @len: maximum length @len should be interpreted to 2742c2fd68b6SChristian Brauner * 2743c2fd68b6SChristian Brauner * Note that this routine is purely a helper for filesystem usage and should 2744c2fd68b6SChristian Brauner * not be called by generic code. 2745c2fd68b6SChristian Brauner * 2746c2fd68b6SChristian Brauner * The caller must hold base->i_mutex. 2747c2fd68b6SChristian Brauner */ 2748c2fd68b6SChristian Brauner struct dentry *lookup_one(struct user_namespace *mnt_userns, const char *name, 2749c2fd68b6SChristian Brauner struct dentry *base, int len) 2750c2fd68b6SChristian Brauner { 2751c2fd68b6SChristian Brauner struct dentry *dentry; 2752c2fd68b6SChristian Brauner struct qstr this; 2753c2fd68b6SChristian Brauner int err; 2754c2fd68b6SChristian Brauner 2755c2fd68b6SChristian Brauner WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 2756c2fd68b6SChristian Brauner 2757c2fd68b6SChristian Brauner err = lookup_one_common(mnt_userns, name, base, len, &this); 2758c2fd68b6SChristian Brauner if (err) 2759c2fd68b6SChristian Brauner return ERR_PTR(err); 2760c2fd68b6SChristian Brauner 2761c2fd68b6SChristian Brauner dentry = lookup_dcache(&this, base, 0); 2762c2fd68b6SChristian Brauner return dentry ? dentry : __lookup_slow(&this, base, 0); 2763c2fd68b6SChristian Brauner } 2764c2fd68b6SChristian Brauner EXPORT_SYMBOL(lookup_one); 2765c2fd68b6SChristian Brauner 2766c2fd68b6SChristian Brauner /** 276700675017SChristian Brauner * lookup_one_unlocked - filesystem helper to lookup single pathname component 276800675017SChristian Brauner * @mnt_userns: idmapping of the mount the lookup is performed from 276900675017SChristian Brauner * @name: pathname component to lookup 277000675017SChristian Brauner * @base: base directory to lookup from 277100675017SChristian Brauner * @len: maximum length @len should be interpreted to 277200675017SChristian Brauner * 277300675017SChristian Brauner * Note that this routine is purely a helper for filesystem usage and should 277400675017SChristian Brauner * not be called by generic code. 277500675017SChristian Brauner * 277600675017SChristian Brauner * Unlike lookup_one_len, it should be called without the parent 277700675017SChristian Brauner * i_mutex held, and will take the i_mutex itself if necessary. 277800675017SChristian Brauner */ 277900675017SChristian Brauner struct dentry *lookup_one_unlocked(struct user_namespace *mnt_userns, 278000675017SChristian Brauner const char *name, struct dentry *base, 278100675017SChristian Brauner int len) 278200675017SChristian Brauner { 278300675017SChristian Brauner struct qstr this; 278400675017SChristian Brauner int err; 278500675017SChristian Brauner struct dentry *ret; 278600675017SChristian Brauner 278700675017SChristian Brauner err = lookup_one_common(mnt_userns, name, base, len, &this); 278800675017SChristian Brauner if (err) 278900675017SChristian Brauner return ERR_PTR(err); 279000675017SChristian Brauner 279100675017SChristian Brauner ret = lookup_dcache(&this, base, 0); 279200675017SChristian Brauner if (!ret) 279300675017SChristian Brauner ret = lookup_slow(&this, base, 0); 279400675017SChristian Brauner return ret; 279500675017SChristian Brauner } 279600675017SChristian Brauner EXPORT_SYMBOL(lookup_one_unlocked); 279700675017SChristian Brauner 279800675017SChristian Brauner /** 279900675017SChristian Brauner * lookup_one_positive_unlocked - filesystem helper to lookup single 280000675017SChristian Brauner * pathname component 280100675017SChristian Brauner * @mnt_userns: idmapping of the mount the lookup is performed from 280200675017SChristian Brauner * @name: pathname component to lookup 280300675017SChristian Brauner * @base: base directory to lookup from 280400675017SChristian Brauner * @len: maximum length @len should be interpreted to 280500675017SChristian Brauner * 280600675017SChristian Brauner * This helper will yield ERR_PTR(-ENOENT) on negatives. The helper returns 280700675017SChristian Brauner * known positive or ERR_PTR(). This is what most of the users want. 280800675017SChristian Brauner * 280900675017SChristian Brauner * Note that pinned negative with unlocked parent _can_ become positive at any 281000675017SChristian Brauner * time, so callers of lookup_one_unlocked() need to be very careful; pinned 281100675017SChristian Brauner * positives have >d_inode stable, so this one avoids such problems. 281200675017SChristian Brauner * 281300675017SChristian Brauner * Note that this routine is purely a helper for filesystem usage and should 281400675017SChristian Brauner * not be called by generic code. 281500675017SChristian Brauner * 281600675017SChristian Brauner * The helper should be called without i_mutex held. 281700675017SChristian Brauner */ 281800675017SChristian Brauner struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns, 281900675017SChristian Brauner const char *name, 282000675017SChristian Brauner struct dentry *base, int len) 282100675017SChristian Brauner { 282200675017SChristian Brauner struct dentry *ret = lookup_one_unlocked(mnt_userns, name, base, len); 282300675017SChristian Brauner 282400675017SChristian Brauner if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 282500675017SChristian Brauner dput(ret); 282600675017SChristian Brauner ret = ERR_PTR(-ENOENT); 282700675017SChristian Brauner } 282800675017SChristian Brauner return ret; 282900675017SChristian Brauner } 283000675017SChristian Brauner EXPORT_SYMBOL(lookup_one_positive_unlocked); 283100675017SChristian Brauner 283200675017SChristian Brauner /** 2833bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2834bbddca8eSNeilBrown * @name: pathname component to lookup 2835bbddca8eSNeilBrown * @base: base directory to lookup from 2836bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2837bbddca8eSNeilBrown * 2838bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2839bbddca8eSNeilBrown * not be called by generic code. 2840bbddca8eSNeilBrown * 2841bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2842bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2843bbddca8eSNeilBrown */ 2844bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2845bbddca8eSNeilBrown struct dentry *base, int len) 2846bbddca8eSNeilBrown { 284700675017SChristian Brauner return lookup_one_unlocked(&init_user_ns, name, base, len); 2848bbddca8eSNeilBrown } 2849bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2850bbddca8eSNeilBrown 28516c2d4798SAl Viro /* 28526c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 28536c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 28546c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 28556c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 28566c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 28576c2d4798SAl Viro * this one avoids such problems. 28586c2d4798SAl Viro */ 28596c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 28606c2d4798SAl Viro struct dentry *base, int len) 28616c2d4798SAl Viro { 286200675017SChristian Brauner return lookup_one_positive_unlocked(&init_user_ns, name, base, len); 28636c2d4798SAl Viro } 28646c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 28656c2d4798SAl Viro 2866eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2867eedf265aSEric W. Biederman int path_pts(struct path *path) 2868eedf265aSEric W. Biederman { 2869eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2870eedf265aSEric W. Biederman * the input path. 2871eedf265aSEric W. Biederman */ 2872a6a7eb76SAl Viro struct dentry *parent = dget_parent(path->dentry); 2873a6a7eb76SAl Viro struct dentry *child; 287419f6028aSAl Viro struct qstr this = QSTR_INIT("pts", 3); 2875eedf265aSEric W. Biederman 2876a6a7eb76SAl Viro if (unlikely(!path_connected(path->mnt, parent))) { 2877a6a7eb76SAl Viro dput(parent); 287863b27720SAl Viro return -ENOENT; 2879a6a7eb76SAl Viro } 288063b27720SAl Viro dput(path->dentry); 288163b27720SAl Viro path->dentry = parent; 2882eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2883eedf265aSEric W. Biederman if (!child) 2884eedf265aSEric W. Biederman return -ENOENT; 2885eedf265aSEric W. Biederman 2886eedf265aSEric W. Biederman path->dentry = child; 2887eedf265aSEric W. Biederman dput(parent); 288819f6028aSAl Viro follow_down(path); 2889eedf265aSEric W. Biederman return 0; 2890eedf265aSEric W. Biederman } 2891eedf265aSEric W. Biederman #endif 2892eedf265aSEric W. Biederman 28931fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 28941fa1e7f6SAndy Whitcroft struct path *path, int *empty) 28951da177e4SLinus Torvalds { 2896794ebceaSStephen Brennan struct filename *filename = getname_flags(name, flags, empty); 2897794ebceaSStephen Brennan int ret = filename_lookup(dfd, filename, flags, path, NULL); 2898794ebceaSStephen Brennan 2899794ebceaSStephen Brennan putname(filename); 2900794ebceaSStephen Brennan return ret; 29011da177e4SLinus Torvalds } 2902b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 29031fa1e7f6SAndy Whitcroft 2904ba73d987SChristian Brauner int __check_sticky(struct user_namespace *mnt_userns, struct inode *dir, 2905ba73d987SChristian Brauner struct inode *inode) 29061da177e4SLinus Torvalds { 29078e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2908da9592edSDavid Howells 2909ba73d987SChristian Brauner if (uid_eq(i_uid_into_mnt(mnt_userns, inode), fsuid)) 29101da177e4SLinus Torvalds return 0; 2911ba73d987SChristian Brauner if (uid_eq(i_uid_into_mnt(mnt_userns, dir), fsuid)) 29121da177e4SLinus Torvalds return 0; 2913ba73d987SChristian Brauner return !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FOWNER); 29141da177e4SLinus Torvalds } 2915cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 29161da177e4SLinus Torvalds 29171da177e4SLinus Torvalds /* 29181da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 29191da177e4SLinus Torvalds * whether the type of victim is right. 29201da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 29211da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 29221da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 29231da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 29241da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 29251da177e4SLinus Torvalds * a. be owner of dir, or 29261da177e4SLinus Torvalds * b. be owner of victim, or 29271da177e4SLinus Torvalds * c. have CAP_FOWNER capability 29281da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 29291da177e4SLinus Torvalds * links pointing to it. 29300bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 29310bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 29320bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 29330bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 29340bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 29351da177e4SLinus Torvalds * nfs_async_unlink(). 29361da177e4SLinus Torvalds */ 2937ba73d987SChristian Brauner static int may_delete(struct user_namespace *mnt_userns, struct inode *dir, 2938ba73d987SChristian Brauner struct dentry *victim, bool isdir) 29391da177e4SLinus Torvalds { 294063afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 29411da177e4SLinus Torvalds int error; 29421da177e4SLinus Torvalds 2943b18825a7SDavid Howells if (d_is_negative(victim)) 29441da177e4SLinus Torvalds return -ENOENT; 2945b18825a7SDavid Howells BUG_ON(!inode); 29461da177e4SLinus Torvalds 29471da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2948593d1ce8SEric W. Biederman 2949593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2950ba73d987SChristian Brauner if (!uid_valid(i_uid_into_mnt(mnt_userns, inode)) || 2951ba73d987SChristian Brauner !gid_valid(i_gid_into_mnt(mnt_userns, inode))) 2952593d1ce8SEric W. Biederman return -EOVERFLOW; 2953593d1ce8SEric W. Biederman 29544fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 29551da177e4SLinus Torvalds 2956ba73d987SChristian Brauner error = inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC); 29571da177e4SLinus Torvalds if (error) 29581da177e4SLinus Torvalds return error; 29591da177e4SLinus Torvalds if (IS_APPEND(dir)) 29601da177e4SLinus Torvalds return -EPERM; 2961b18825a7SDavid Howells 2962ba73d987SChristian Brauner if (check_sticky(mnt_userns, dir, inode) || IS_APPEND(inode) || 2963ba73d987SChristian Brauner IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || 2964ba73d987SChristian Brauner HAS_UNMAPPED_ID(mnt_userns, inode)) 29651da177e4SLinus Torvalds return -EPERM; 29661da177e4SLinus Torvalds if (isdir) { 296744b1d530SMiklos Szeredi if (!d_is_dir(victim)) 29681da177e4SLinus Torvalds return -ENOTDIR; 29691da177e4SLinus Torvalds if (IS_ROOT(victim)) 29701da177e4SLinus Torvalds return -EBUSY; 297144b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 29721da177e4SLinus Torvalds return -EISDIR; 29731da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 29741da177e4SLinus Torvalds return -ENOENT; 29751da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 29761da177e4SLinus Torvalds return -EBUSY; 29771da177e4SLinus Torvalds return 0; 29781da177e4SLinus Torvalds } 29791da177e4SLinus Torvalds 29801da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 29811da177e4SLinus Torvalds * dir. 29821da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 29831da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 29841da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2985036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2986036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2987036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 29881da177e4SLinus Torvalds */ 2989ba73d987SChristian Brauner static inline int may_create(struct user_namespace *mnt_userns, 2990ba73d987SChristian Brauner struct inode *dir, struct dentry *child) 29911da177e4SLinus Torvalds { 299214e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 29931da177e4SLinus Torvalds if (child->d_inode) 29941da177e4SLinus Torvalds return -EEXIST; 29951da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 29961da177e4SLinus Torvalds return -ENOENT; 29978e538913SChristian Brauner if (!fsuidgid_has_mapping(dir->i_sb, mnt_userns)) 2998036d5236SEric W. Biederman return -EOVERFLOW; 29998e538913SChristian Brauner 3000ba73d987SChristian Brauner return inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC); 30011da177e4SLinus Torvalds } 30021da177e4SLinus Torvalds 30031da177e4SLinus Torvalds /* 30041da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 30051da177e4SLinus Torvalds */ 30061da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 30071da177e4SLinus Torvalds { 30081da177e4SLinus Torvalds struct dentry *p; 30091da177e4SLinus Torvalds 30101da177e4SLinus Torvalds if (p1 == p2) { 30115955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 30121da177e4SLinus Torvalds return NULL; 30131da177e4SLinus Torvalds } 30141da177e4SLinus Torvalds 3015fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 30161da177e4SLinus Torvalds 3017e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 3018e2761a11SOGAWA Hirofumi if (p) { 30195955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 30205955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 30211da177e4SLinus Torvalds return p; 30221da177e4SLinus Torvalds } 30231da177e4SLinus Torvalds 3024e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 3025e2761a11SOGAWA Hirofumi if (p) { 30265955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 30275955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 30281da177e4SLinus Torvalds return p; 30291da177e4SLinus Torvalds } 30301da177e4SLinus Torvalds 30315955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 30325955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 30331da177e4SLinus Torvalds return NULL; 30341da177e4SLinus Torvalds } 30354d359507SAl Viro EXPORT_SYMBOL(lock_rename); 30361da177e4SLinus Torvalds 30371da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 30381da177e4SLinus Torvalds { 30395955102cSAl Viro inode_unlock(p1->d_inode); 30401da177e4SLinus Torvalds if (p1 != p2) { 30415955102cSAl Viro inode_unlock(p2->d_inode); 3042fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 30431da177e4SLinus Torvalds } 30441da177e4SLinus Torvalds } 30454d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 30461da177e4SLinus Torvalds 30476521f891SChristian Brauner /** 30486521f891SChristian Brauner * vfs_create - create new file 30496521f891SChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 30506521f891SChristian Brauner * @dir: inode of @dentry 30516521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 30526521f891SChristian Brauner * @mode: mode of the new file 30536521f891SChristian Brauner * @want_excl: whether the file must not yet exist 30546521f891SChristian Brauner * 30556521f891SChristian Brauner * Create a new file. 30566521f891SChristian Brauner * 30576521f891SChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 30586521f891SChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 30596521f891SChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 30606521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 30616521f891SChristian Brauner * raw inode simply passs init_user_ns. 30626521f891SChristian Brauner */ 30636521f891SChristian Brauner int vfs_create(struct user_namespace *mnt_userns, struct inode *dir, 30646521f891SChristian Brauner struct dentry *dentry, umode_t mode, bool want_excl) 30651da177e4SLinus Torvalds { 30666521f891SChristian Brauner int error = may_create(mnt_userns, dir, dentry); 30671da177e4SLinus Torvalds if (error) 30681da177e4SLinus Torvalds return error; 30691da177e4SLinus Torvalds 3070acfa4380SAl Viro if (!dir->i_op->create) 30711da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 30721da177e4SLinus Torvalds mode &= S_IALLUGO; 30731da177e4SLinus Torvalds mode |= S_IFREG; 30741da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 30751da177e4SLinus Torvalds if (error) 30761da177e4SLinus Torvalds return error; 3077549c7297SChristian Brauner error = dir->i_op->create(mnt_userns, dir, dentry, mode, want_excl); 3078a74574aaSStephen Smalley if (!error) 3079f38aa942SAmy Griffis fsnotify_create(dir, dentry); 30801da177e4SLinus Torvalds return error; 30811da177e4SLinus Torvalds } 30824d359507SAl Viro EXPORT_SYMBOL(vfs_create); 30831da177e4SLinus Torvalds 30848e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 30858e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 30868e6c848eSAl Viro void *arg) 30878e6c848eSAl Viro { 30888e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 3089ba73d987SChristian Brauner int error = may_create(&init_user_ns, dir, dentry); 30908e6c848eSAl Viro if (error) 30918e6c848eSAl Viro return error; 30928e6c848eSAl Viro 30938e6c848eSAl Viro mode &= S_IALLUGO; 30948e6c848eSAl Viro mode |= S_IFREG; 30958e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 30968e6c848eSAl Viro if (error) 30978e6c848eSAl Viro return error; 30988e6c848eSAl Viro error = f(dentry, mode, arg); 30998e6c848eSAl Viro if (!error) 31008e6c848eSAl Viro fsnotify_create(dir, dentry); 31018e6c848eSAl Viro return error; 31028e6c848eSAl Viro } 31038e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 31048e6c848eSAl Viro 3105a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 3106a2982cc9SEric W. Biederman { 3107a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 3108a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 3109a2982cc9SEric W. Biederman } 3110a2982cc9SEric W. Biederman 3111ba73d987SChristian Brauner static int may_open(struct user_namespace *mnt_userns, const struct path *path, 3112ba73d987SChristian Brauner int acc_mode, int flag) 31131da177e4SLinus Torvalds { 31143fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 31151da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 31161da177e4SLinus Torvalds int error; 31171da177e4SLinus Torvalds 31181da177e4SLinus Torvalds if (!inode) 31191da177e4SLinus Torvalds return -ENOENT; 31201da177e4SLinus Torvalds 3121c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 3122c8fe8f30SChristoph Hellwig case S_IFLNK: 31231da177e4SLinus Torvalds return -ELOOP; 3124c8fe8f30SChristoph Hellwig case S_IFDIR: 3125fc4177beSKees Cook if (acc_mode & MAY_WRITE) 31261da177e4SLinus Torvalds return -EISDIR; 3127fc4177beSKees Cook if (acc_mode & MAY_EXEC) 3128fc4177beSKees Cook return -EACCES; 3129c8fe8f30SChristoph Hellwig break; 3130c8fe8f30SChristoph Hellwig case S_IFBLK: 3131c8fe8f30SChristoph Hellwig case S_IFCHR: 3132a2982cc9SEric W. Biederman if (!may_open_dev(path)) 31331da177e4SLinus Torvalds return -EACCES; 3134633fb6acSKees Cook fallthrough; 3135c8fe8f30SChristoph Hellwig case S_IFIFO: 3136c8fe8f30SChristoph Hellwig case S_IFSOCK: 3137633fb6acSKees Cook if (acc_mode & MAY_EXEC) 3138633fb6acSKees Cook return -EACCES; 31391da177e4SLinus Torvalds flag &= ~O_TRUNC; 3140c8fe8f30SChristoph Hellwig break; 31410fd338b2SKees Cook case S_IFREG: 31420fd338b2SKees Cook if ((acc_mode & MAY_EXEC) && path_noexec(path)) 31430fd338b2SKees Cook return -EACCES; 31440fd338b2SKees Cook break; 31454a3fd211SDave Hansen } 3146b41572e9SDave Hansen 3147ba73d987SChristian Brauner error = inode_permission(mnt_userns, inode, MAY_OPEN | acc_mode); 3148b41572e9SDave Hansen if (error) 3149b41572e9SDave Hansen return error; 31506146f0d5SMimi Zohar 31511da177e4SLinus Torvalds /* 31521da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 31531da177e4SLinus Torvalds */ 31541da177e4SLinus Torvalds if (IS_APPEND(inode)) { 31558737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 31567715b521SAl Viro return -EPERM; 31571da177e4SLinus Torvalds if (flag & O_TRUNC) 31587715b521SAl Viro return -EPERM; 31591da177e4SLinus Torvalds } 31601da177e4SLinus Torvalds 31611da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 3162ba73d987SChristian Brauner if (flag & O_NOATIME && !inode_owner_or_capable(mnt_userns, inode)) 31637715b521SAl Viro return -EPERM; 31641da177e4SLinus Torvalds 3165f3c7691eSJ. Bruce Fields return 0; 31667715b521SAl Viro } 31677715b521SAl Viro 3168549c7297SChristian Brauner static int handle_truncate(struct user_namespace *mnt_userns, struct file *filp) 31697715b521SAl Viro { 3170f0bb5aafSAl Viro const struct path *path = &filp->f_path; 31717715b521SAl Viro struct inode *inode = path->dentry->d_inode; 31727715b521SAl Viro int error = get_write_access(inode); 31731da177e4SLinus Torvalds if (error) 31747715b521SAl Viro return error; 3175482e0007SJeff Layton 3176ea0d3ab2STetsuo Handa error = security_path_truncate(path); 31771da177e4SLinus Torvalds if (!error) { 3178549c7297SChristian Brauner error = do_truncate(mnt_userns, path->dentry, 0, 3179d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 3180e1181ee6SJeff Layton filp); 31811da177e4SLinus Torvalds } 31821da177e4SLinus Torvalds put_write_access(inode); 3183acd0c935SMimi Zohar return error; 31841da177e4SLinus Torvalds } 31851da177e4SLinus Torvalds 3186d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 3187d57999e1SDave Hansen { 31888a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 31898a5e929dSAl Viro flag--; 3190d57999e1SDave Hansen return flag; 3191d57999e1SDave Hansen } 3192d57999e1SDave Hansen 3193ba73d987SChristian Brauner static int may_o_create(struct user_namespace *mnt_userns, 3194ba73d987SChristian Brauner const struct path *dir, struct dentry *dentry, 3195ba73d987SChristian Brauner umode_t mode) 3196d18e9008SMiklos Szeredi { 3197d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 3198d18e9008SMiklos Szeredi if (error) 3199d18e9008SMiklos Szeredi return error; 3200d18e9008SMiklos Szeredi 32018e538913SChristian Brauner if (!fsuidgid_has_mapping(dir->dentry->d_sb, mnt_userns)) 32021328c727SSeth Forshee return -EOVERFLOW; 32031328c727SSeth Forshee 3204ba73d987SChristian Brauner error = inode_permission(mnt_userns, dir->dentry->d_inode, 320547291baaSChristian Brauner MAY_WRITE | MAY_EXEC); 3206d18e9008SMiklos Szeredi if (error) 3207d18e9008SMiklos Szeredi return error; 3208d18e9008SMiklos Szeredi 3209d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 3210d18e9008SMiklos Szeredi } 3211d18e9008SMiklos Szeredi 32121acf0af9SDavid Howells /* 32131acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 32141acf0af9SDavid Howells * dentry. 32151acf0af9SDavid Howells * 32161acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 32171acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 32181acf0af9SDavid Howells * 321900a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 322000a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 322100a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 32221acf0af9SDavid Howells * 32231acf0af9SDavid Howells * Returns an error code otherwise. 32241acf0af9SDavid Howells */ 3225239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 3226239eb983SAl Viro struct file *file, 32273ec2eef1SAl Viro int open_flag, umode_t mode) 3228d18e9008SMiklos Szeredi { 3229d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3230d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3231d18e9008SMiklos Szeredi int error; 3232d18e9008SMiklos Szeredi 3233d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3234d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3235d18e9008SMiklos Szeredi 323630d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 323730d90494SAl Viro file->f_path.mnt = nd->path.mnt; 32380fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 323944907d79SAl Viro open_to_namei_flags(open_flag), mode); 32406fbd0714SAl Viro d_lookup_done(dentry); 3241384f26e2SAl Viro if (!error) { 324264e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 32436fb968cdSAl Viro if (unlikely(dentry != file->f_path.dentry)) { 32446fb968cdSAl Viro dput(dentry); 32456fb968cdSAl Viro dentry = dget(file->f_path.dentry); 32466fb968cdSAl Viro } 324764e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 32482675a4ebSAl Viro error = -EIO; 3249384f26e2SAl Viro } else { 325030d90494SAl Viro if (file->f_path.dentry) { 3251d18e9008SMiklos Szeredi dput(dentry); 3252d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 325310c64ceaSAl Viro } 3254239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 3255a01e718fSAl Viro error = -ENOENT; 3256d18e9008SMiklos Szeredi } 3257d18e9008SMiklos Szeredi } 3258239eb983SAl Viro if (error) { 3259d18e9008SMiklos Szeredi dput(dentry); 3260239eb983SAl Viro dentry = ERR_PTR(error); 3261239eb983SAl Viro } 3262239eb983SAl Viro return dentry; 3263d18e9008SMiklos Szeredi } 3264d18e9008SMiklos Szeredi 326531e6b01fSNick Piggin /* 32661acf0af9SDavid Howells * Look up and maybe create and open the last component. 3267d58ffd35SMiklos Szeredi * 326800a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3269d58ffd35SMiklos Szeredi * 327000a07c15SAl Viro * Returns 0 on success, that is, if 327100a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 327200a07c15SAl Viro * the file was not completely opened at this time, though lookups and 327300a07c15SAl Viro * creations were performed. 327400a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 327500a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 327600a07c15SAl Viro * hadn't been specified. 32771acf0af9SDavid Howells * 327800a07c15SAl Viro * An error code is returned on failure. 3279d58ffd35SMiklos Szeredi */ 3280da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 3281d58ffd35SMiklos Szeredi const struct open_flags *op, 32823ec2eef1SAl Viro bool got_write) 3283d58ffd35SMiklos Szeredi { 3284549c7297SChristian Brauner struct user_namespace *mnt_userns; 3285d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 328654ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 32871643b43fSAl Viro int open_flag = op->open_flag; 3288d58ffd35SMiklos Szeredi struct dentry *dentry; 32891643b43fSAl Viro int error, create_error = 0; 32901643b43fSAl Viro umode_t mode = op->mode; 32916fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3292d58ffd35SMiklos Szeredi 3293ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3294da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 3295d58ffd35SMiklos Szeredi 329673a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 32976fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 32986fbd0714SAl Viro for (;;) { 32996fbd0714SAl Viro if (!dentry) { 33006fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3301d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 3302da5ebf5aSAl Viro return dentry; 33036fbd0714SAl Viro } 33046fbd0714SAl Viro if (d_in_lookup(dentry)) 33056fbd0714SAl Viro break; 3306d58ffd35SMiklos Szeredi 33076fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 33086fbd0714SAl Viro if (likely(error > 0)) 33096fbd0714SAl Viro break; 33106fbd0714SAl Viro if (error) 33116fbd0714SAl Viro goto out_dput; 33126fbd0714SAl Viro d_invalidate(dentry); 33136fbd0714SAl Viro dput(dentry); 33146fbd0714SAl Viro dentry = NULL; 33156fbd0714SAl Viro } 33166fbd0714SAl Viro if (dentry->d_inode) { 3317d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3318da5ebf5aSAl Viro return dentry; 33196c51e513SAl Viro } 3320d18e9008SMiklos Szeredi 33211643b43fSAl Viro /* 33221643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 33231643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 33241643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 33251643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 33261643b43fSAl Viro * 33271643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 33281643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 33291643b43fSAl Viro */ 333099a4a90cSAl Viro if (unlikely(!got_write)) 333199a4a90cSAl Viro open_flag &= ~O_TRUNC; 3332549c7297SChristian Brauner mnt_userns = mnt_user_ns(nd->path.mnt); 33331643b43fSAl Viro if (open_flag & O_CREAT) { 333499a4a90cSAl Viro if (open_flag & O_EXCL) 333599a4a90cSAl Viro open_flag &= ~O_TRUNC; 33361643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 33371643b43fSAl Viro mode &= ~current_umask(); 333899a4a90cSAl Viro if (likely(got_write)) 3339549c7297SChristian Brauner create_error = may_o_create(mnt_userns, &nd->path, 3340ba73d987SChristian Brauner dentry, mode); 334199a4a90cSAl Viro else 334299a4a90cSAl Viro create_error = -EROFS; 334399a4a90cSAl Viro } 334499a4a90cSAl Viro if (create_error) 33451643b43fSAl Viro open_flag &= ~O_CREAT; 33461643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3347d489cf9aSAl Viro dentry = atomic_open(nd, dentry, file, open_flag, mode); 3348da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3349da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3350da5ebf5aSAl Viro return dentry; 3351239eb983SAl Viro } 335254ef4872SMiklos Szeredi 33536fbd0714SAl Viro if (d_in_lookup(dentry)) { 335412fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 335512fa5e24SAl Viro nd->flags); 33566fbd0714SAl Viro d_lookup_done(dentry); 335712fa5e24SAl Viro if (unlikely(res)) { 335812fa5e24SAl Viro if (IS_ERR(res)) { 335912fa5e24SAl Viro error = PTR_ERR(res); 336012fa5e24SAl Viro goto out_dput; 336112fa5e24SAl Viro } 336212fa5e24SAl Viro dput(dentry); 336312fa5e24SAl Viro dentry = res; 336412fa5e24SAl Viro } 336554ef4872SMiklos Szeredi } 336654ef4872SMiklos Szeredi 3367d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 33681643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 336973a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3370ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3371ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3372ce8644fcSAl Viro error = -EACCES; 3373d58ffd35SMiklos Szeredi goto out_dput; 337464894cf8SAl Viro } 3375549c7297SChristian Brauner 3376549c7297SChristian Brauner error = dir_inode->i_op->create(mnt_userns, dir_inode, dentry, 3377549c7297SChristian Brauner mode, open_flag & O_EXCL); 3378d58ffd35SMiklos Szeredi if (error) 3379d58ffd35SMiklos Szeredi goto out_dput; 3380d58ffd35SMiklos Szeredi } 33811643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 33821643b43fSAl Viro error = create_error; 3383d58ffd35SMiklos Szeredi goto out_dput; 3384d58ffd35SMiklos Szeredi } 3385da5ebf5aSAl Viro return dentry; 3386d58ffd35SMiklos Szeredi 3387d58ffd35SMiklos Szeredi out_dput: 3388d58ffd35SMiklos Szeredi dput(dentry); 3389da5ebf5aSAl Viro return ERR_PTR(error); 3390d58ffd35SMiklos Szeredi } 3391d58ffd35SMiklos Szeredi 3392c981a482SAl Viro static const char *open_last_lookups(struct nameidata *nd, 33933ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3394fb1cc555SAl Viro { 3395a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3396ca344a89SAl Viro int open_flag = op->open_flag; 339764894cf8SAl Viro bool got_write = false; 3398254cf582SAl Viro unsigned seq; 3399a1eb3315SMiklos Szeredi struct inode *inode; 3400da5ebf5aSAl Viro struct dentry *dentry; 3401b0417d2cSAl Viro const char *res; 3402fb1cc555SAl Viro 3403c3e380b0SAl Viro nd->flags |= op->intent; 3404c3e380b0SAl Viro 3405bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 340656676ec3SAl Viro if (nd->depth) 340756676ec3SAl Viro put_link(nd); 3408ff326a32SAl Viro return handle_dots(nd, nd->last_type); 34091f36f774SAl Viro } 3410a2c36b45SAl Viro 3411ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3412fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3413fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3414fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 341520e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 341620e34357SAl Viro if (IS_ERR(dentry)) 34171ccac622SAl Viro return ERR_CAST(dentry); 341820e34357SAl Viro if (likely(dentry)) 341971574865SMiklos Szeredi goto finish_lookup; 342071574865SMiklos Szeredi 34216583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3422b6183df7SMiklos Szeredi } else { 3423fe2d35ffSAl Viro /* create side of things */ 342472287417SAl Viro if (nd->flags & LOOKUP_RCU) { 3425e36cffedSJens Axboe if (!try_to_unlazy(nd)) 3426e36cffedSJens Axboe return ERR_PTR(-ECHILD); 342772287417SAl Viro } 3428c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 34291f36f774SAl Viro /* trailing slashes? */ 3430deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 34311ccac622SAl Viro return ERR_PTR(-EISDIR); 3432b6183df7SMiklos Szeredi } 34331f36f774SAl Viro 34349cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 3435e36cffedSJens Axboe got_write = !mnt_want_write(nd->path.mnt); 343664894cf8SAl Viro /* 343764894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 343864894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 343964894cf8SAl Viro * dropping this one anyway. 344064894cf8SAl Viro */ 344164894cf8SAl Viro } 34429cf843e3SAl Viro if (open_flag & O_CREAT) 34435955102cSAl Viro inode_lock(dir->d_inode); 34449cf843e3SAl Viro else 34459cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3446da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 3447f7bb959dSAl Viro if (!IS_ERR(dentry) && (file->f_mode & FMODE_CREATED)) 3448f7bb959dSAl Viro fsnotify_create(dir->d_inode, dentry); 34499cf843e3SAl Viro if (open_flag & O_CREAT) 34505955102cSAl Viro inode_unlock(dir->d_inode); 34519cf843e3SAl Viro else 34529cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3453fb1cc555SAl Viro 3454c981a482SAl Viro if (got_write) 345559e96e65SAl Viro mnt_drop_write(nd->path.mnt); 34566c0d46c4SAl Viro 345759e96e65SAl Viro if (IS_ERR(dentry)) 345859e96e65SAl Viro return ERR_CAST(dentry); 345959e96e65SAl Viro 3460973d4b73SAl Viro if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) { 3461e73cabffSAl Viro dput(nd->path.dentry); 3462e73cabffSAl Viro nd->path.dentry = dentry; 3463c981a482SAl Viro return NULL; 3464fb1cc555SAl Viro } 3465fb1cc555SAl Viro 346620e34357SAl Viro finish_lookup: 346756676ec3SAl Viro if (nd->depth) 346856676ec3SAl Viro put_link(nd); 34698c4efe22SAl Viro res = step_into(nd, WALK_TRAILING, dentry, inode, seq); 3470ff326a32SAl Viro if (unlikely(res)) 34711ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3472b0417d2cSAl Viro return res; 34731ccac622SAl Viro } 347431d1726dSAl Viro 3475c981a482SAl Viro /* 3476c981a482SAl Viro * Handle the last step of open() 3477c981a482SAl Viro */ 3478c5971b8cSAl Viro static int do_open(struct nameidata *nd, 3479c981a482SAl Viro struct file *file, const struct open_flags *op) 3480c981a482SAl Viro { 3481549c7297SChristian Brauner struct user_namespace *mnt_userns; 3482c981a482SAl Viro int open_flag = op->open_flag; 3483c981a482SAl Viro bool do_truncate; 3484c981a482SAl Viro int acc_mode; 3485c981a482SAl Viro int error; 3486c981a482SAl Viro 3487ff326a32SAl Viro if (!(file->f_mode & (FMODE_OPENED | FMODE_CREATED))) { 3488ff326a32SAl Viro error = complete_walk(nd); 3489ff326a32SAl Viro if (error) 3490ff326a32SAl Viro return error; 3491ff326a32SAl Viro } 3492973d4b73SAl Viro if (!(file->f_mode & FMODE_CREATED)) 349376ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3494549c7297SChristian Brauner mnt_userns = mnt_user_ns(nd->path.mnt); 349530aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3496b94e0b32SAl Viro if ((open_flag & O_EXCL) && !(file->f_mode & FMODE_CREATED)) 3497b94e0b32SAl Viro return -EEXIST; 349830aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 3499c5971b8cSAl Viro return -EISDIR; 3500549c7297SChristian Brauner error = may_create_in_sticky(mnt_userns, nd, 350130aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 350230aba665SSalvatore Mesoraca if (unlikely(error)) 3503c5971b8cSAl Viro return error; 350430aba665SSalvatore Mesoraca } 350544b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 3506c5971b8cSAl Viro return -ENOTDIR; 35076c0d46c4SAl Viro 35088795e7d4SAl Viro do_truncate = false; 35098795e7d4SAl Viro acc_mode = op->acc_mode; 35105a2d3eddSAl Viro if (file->f_mode & FMODE_CREATED) { 35115a2d3eddSAl Viro /* Don't check for write permission, don't truncate */ 35125a2d3eddSAl Viro open_flag &= ~O_TRUNC; 35135a2d3eddSAl Viro acc_mode = 0; 35148795e7d4SAl Viro } else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) { 35150f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 35160f9d1a10SAl Viro if (error) 3517c5971b8cSAl Viro return error; 35188795e7d4SAl Viro do_truncate = true; 35190f9d1a10SAl Viro } 3520549c7297SChristian Brauner error = may_open(mnt_userns, &nd->path, acc_mode, open_flag); 35218795e7d4SAl Viro if (!error && !(file->f_mode & FMODE_OPENED)) 3522ae2bb293SAl Viro error = vfs_open(&nd->path, file); 35238795e7d4SAl Viro if (!error) 35246035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 35258795e7d4SAl Viro if (!error && do_truncate) 3526549c7297SChristian Brauner error = handle_truncate(mnt_userns, file); 3527c80567c8SAl Viro if (unlikely(error > 0)) { 3528c80567c8SAl Viro WARN_ON(1); 3529c80567c8SAl Viro error = -EINVAL; 3530c80567c8SAl Viro } 35318795e7d4SAl Viro if (do_truncate) 35320f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 3533c5971b8cSAl Viro return error; 3534fb1cc555SAl Viro } 3535fb1cc555SAl Viro 35366521f891SChristian Brauner /** 35376521f891SChristian Brauner * vfs_tmpfile - create tmpfile 35386521f891SChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 35396521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 35406521f891SChristian Brauner * @mode: mode of the new tmpfile 35412111c3c0SRandy Dunlap * @open_flag: flags 35426521f891SChristian Brauner * 35436521f891SChristian Brauner * Create a temporary file. 35446521f891SChristian Brauner * 35456521f891SChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 35466521f891SChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 35476521f891SChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 35486521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 35496521f891SChristian Brauner * raw inode simply passs init_user_ns. 35506521f891SChristian Brauner */ 35516521f891SChristian Brauner struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns, 35526521f891SChristian Brauner struct dentry *dentry, umode_t mode, int open_flag) 3553af7bd4dcSAmir Goldstein { 3554af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3555af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3556af7bd4dcSAmir Goldstein struct inode *inode; 3557af7bd4dcSAmir Goldstein int error; 3558af7bd4dcSAmir Goldstein 3559af7bd4dcSAmir Goldstein /* we want directory to be writable */ 35606521f891SChristian Brauner error = inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC); 3561af7bd4dcSAmir Goldstein if (error) 3562af7bd4dcSAmir Goldstein goto out_err; 3563af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3564af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3565af7bd4dcSAmir Goldstein goto out_err; 3566af7bd4dcSAmir Goldstein error = -ENOMEM; 3567cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3568af7bd4dcSAmir Goldstein if (unlikely(!child)) 3569af7bd4dcSAmir Goldstein goto out_err; 3570549c7297SChristian Brauner error = dir->i_op->tmpfile(mnt_userns, dir, child, mode); 3571af7bd4dcSAmir Goldstein if (error) 3572af7bd4dcSAmir Goldstein goto out_err; 3573af7bd4dcSAmir Goldstein error = -ENOENT; 3574af7bd4dcSAmir Goldstein inode = child->d_inode; 3575af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3576af7bd4dcSAmir Goldstein goto out_err; 3577af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3578af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3579af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3580af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3581af7bd4dcSAmir Goldstein } 3582a2d2329eSChristian Brauner ima_post_create_tmpfile(mnt_userns, inode); 3583af7bd4dcSAmir Goldstein return child; 3584af7bd4dcSAmir Goldstein 3585af7bd4dcSAmir Goldstein out_err: 3586af7bd4dcSAmir Goldstein dput(child); 3587af7bd4dcSAmir Goldstein return ERR_PTR(error); 3588af7bd4dcSAmir Goldstein } 3589af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3590af7bd4dcSAmir Goldstein 3591c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 359260545d0dSAl Viro const struct open_flags *op, 35933ec2eef1SAl Viro struct file *file) 359460545d0dSAl Viro { 35956521f891SChristian Brauner struct user_namespace *mnt_userns; 3596625b6d10SAl Viro struct dentry *child; 3597625b6d10SAl Viro struct path path; 3598c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 359960545d0dSAl Viro if (unlikely(error)) 360060545d0dSAl Viro return error; 3601625b6d10SAl Viro error = mnt_want_write(path.mnt); 360260545d0dSAl Viro if (unlikely(error)) 360360545d0dSAl Viro goto out; 36046521f891SChristian Brauner mnt_userns = mnt_user_ns(path.mnt); 36056521f891SChristian Brauner child = vfs_tmpfile(mnt_userns, path.dentry, op->mode, op->open_flag); 3606af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3607684e73beSHirofumi Nakagawa if (IS_ERR(child)) 360860545d0dSAl Viro goto out2; 3609625b6d10SAl Viro dput(path.dentry); 3610625b6d10SAl Viro path.dentry = child; 3611c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 361269a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 3613549c7297SChristian Brauner error = may_open(mnt_userns, &path, 0, op->open_flag); 36141e8f44f1SAl Viro if (!error) 36151e8f44f1SAl Viro error = vfs_open(&path, file); 361660545d0dSAl Viro out2: 3617625b6d10SAl Viro mnt_drop_write(path.mnt); 361860545d0dSAl Viro out: 3619625b6d10SAl Viro path_put(&path); 362060545d0dSAl Viro return error; 362160545d0dSAl Viro } 362260545d0dSAl Viro 36236ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 36246ac08709SAl Viro { 36256ac08709SAl Viro struct path path; 36266ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 36276ac08709SAl Viro if (!error) { 36286ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3629ae2bb293SAl Viro error = vfs_open(&path, file); 36306ac08709SAl Viro path_put(&path); 36316ac08709SAl Viro } 36326ac08709SAl Viro return error; 36336ac08709SAl Viro } 36346ac08709SAl Viro 3635c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3636c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 36371da177e4SLinus Torvalds { 363830d90494SAl Viro struct file *file; 363913aab428SAl Viro int error; 364031e6b01fSNick Piggin 3641ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 36421afc99beSAl Viro if (IS_ERR(file)) 36431afc99beSAl Viro return file; 364431e6b01fSNick Piggin 3645bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 36463ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 36475f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 36486ac08709SAl Viro error = do_o_path(nd, flags, file); 36495f336e72SAl Viro } else { 36505f336e72SAl Viro const char *s = path_init(nd, flags); 36513bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 3652c5971b8cSAl Viro (s = open_last_lookups(nd, file, op)) != NULL) 36531ccac622SAl Viro ; 3654c5971b8cSAl Viro if (!error) 3655c5971b8cSAl Viro error = do_open(nd, file, op); 3656deb106c6SAl Viro terminate_walk(nd); 36575f336e72SAl Viro } 36587c1c01ecSAl Viro if (likely(!error)) { 3659aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 36607c1c01ecSAl Viro return file; 36617c1c01ecSAl Viro WARN_ON(1); 36627c1c01ecSAl Viro error = -EINVAL; 3663015c3bbcSMiklos Szeredi } 36647c1c01ecSAl Viro fput(file); 36652675a4ebSAl Viro if (error == -EOPENSTALE) { 36662675a4ebSAl Viro if (flags & LOOKUP_RCU) 36672675a4ebSAl Viro error = -ECHILD; 36682675a4ebSAl Viro else 36692675a4ebSAl Viro error = -ESTALE; 36702675a4ebSAl Viro } 36717c1c01ecSAl Viro return ERR_PTR(error); 3672de459215SKirill Korotaev } 36731da177e4SLinus Torvalds 3674669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3675f9652e10SAl Viro const struct open_flags *op) 367613aab428SAl Viro { 36779883d185SAl Viro struct nameidata nd; 3678f9652e10SAl Viro int flags = op->lookup_flags; 367913aab428SAl Viro struct file *filp; 368013aab428SAl Viro 368106422964SAl Viro set_nameidata(&nd, dfd, pathname, NULL); 3682c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 368313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3684c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 368513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3686c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 36879883d185SAl Viro restore_nameidata(); 368813aab428SAl Viro return filp; 368913aab428SAl Viro } 369013aab428SAl Viro 3691ffb37ca3SAl Viro struct file *do_file_open_root(const struct path *root, 3692f9652e10SAl Viro const char *name, const struct open_flags *op) 369373d049a4SAl Viro { 36949883d185SAl Viro struct nameidata nd; 369573d049a4SAl Viro struct file *file; 369651689104SPaul Moore struct filename *filename; 3697bcba1e7dSAl Viro int flags = op->lookup_flags; 369873d049a4SAl Viro 3699ffb37ca3SAl Viro if (d_is_symlink(root->dentry) && op->intent & LOOKUP_OPEN) 370073d049a4SAl Viro return ERR_PTR(-ELOOP); 370173d049a4SAl Viro 370251689104SPaul Moore filename = getname_kernel(name); 3703a1c83681SViresh Kumar if (IS_ERR(filename)) 370451689104SPaul Moore return ERR_CAST(filename); 370551689104SPaul Moore 370606422964SAl Viro set_nameidata(&nd, -1, filename, root); 3707c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 370873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3709c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 371073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3711c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 37129883d185SAl Viro restore_nameidata(); 371351689104SPaul Moore putname(filename); 371473d049a4SAl Viro return file; 371573d049a4SAl Viro } 371673d049a4SAl Viro 3717b4a4f213SStephen Brennan static struct dentry *filename_create(int dfd, struct filename *name, 37181ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 37191da177e4SLinus Torvalds { 3720c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3721391172c4SAl Viro struct qstr last; 3722b3d4650dSNeilBrown bool want_dir = lookup_flags & LOOKUP_DIRECTORY; 3723b3d4650dSNeilBrown unsigned int reval_flag = lookup_flags & LOOKUP_REVAL; 3724b3d4650dSNeilBrown unsigned int create_flags = LOOKUP_CREATE | LOOKUP_EXCL; 3725391172c4SAl Viro int type; 3726c30dabfeSJan Kara int err2; 37271ac12b4bSJeff Layton int error; 37281ac12b4bSJeff Layton 3729b3d4650dSNeilBrown error = filename_parentat(dfd, name, reval_flag, path, &last, &type); 37300ee50b47SDmitry Kadashev if (error) 37310ee50b47SDmitry Kadashev return ERR_PTR(error); 37321da177e4SLinus Torvalds 3733c663e5d8SChristoph Hellwig /* 3734c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3735c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3736c663e5d8SChristoph Hellwig */ 37375c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3738ed75e95dSAl Viro goto out; 3739c663e5d8SChristoph Hellwig 3740c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3741391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3742c663e5d8SChristoph Hellwig /* 3743b3d4650dSNeilBrown * Do the final lookup. Suppress 'create' if there is a trailing 3744b3d4650dSNeilBrown * '/', and a directory wasn't requested. 3745c663e5d8SChristoph Hellwig */ 3746b3d4650dSNeilBrown if (last.name[last.len] && !want_dir) 3747b3d4650dSNeilBrown create_flags = 0; 37485955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3749b3d4650dSNeilBrown dentry = __lookup_hash(&last, path->dentry, reval_flag | create_flags); 37501da177e4SLinus Torvalds if (IS_ERR(dentry)) 3751a8104a9fSAl Viro goto unlock; 3752c663e5d8SChristoph Hellwig 3753a8104a9fSAl Viro error = -EEXIST; 3754b18825a7SDavid Howells if (d_is_positive(dentry)) 3755a8104a9fSAl Viro goto fail; 3756b18825a7SDavid Howells 3757c663e5d8SChristoph Hellwig /* 3758c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3759c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3760c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3761c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3762c663e5d8SChristoph Hellwig */ 3763b3d4650dSNeilBrown if (unlikely(!create_flags)) { 3764a8104a9fSAl Viro error = -ENOENT; 3765ed75e95dSAl Viro goto fail; 3766e9baf6e5SAl Viro } 3767c30dabfeSJan Kara if (unlikely(err2)) { 3768c30dabfeSJan Kara error = err2; 3769a8104a9fSAl Viro goto fail; 3770c30dabfeSJan Kara } 3771e9baf6e5SAl Viro return dentry; 37721da177e4SLinus Torvalds fail: 3773a8104a9fSAl Viro dput(dentry); 3774a8104a9fSAl Viro dentry = ERR_PTR(error); 3775a8104a9fSAl Viro unlock: 37765955102cSAl Viro inode_unlock(path->dentry->d_inode); 3777c30dabfeSJan Kara if (!err2) 3778391172c4SAl Viro mnt_drop_write(path->mnt); 3779ed75e95dSAl Viro out: 3780391172c4SAl Viro path_put(path); 3781ed75e95dSAl Viro return dentry; 3782dae6ad8fSAl Viro } 3783fa14a0b8SAl Viro 3784fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3785fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3786fa14a0b8SAl Viro { 3787b4a4f213SStephen Brennan struct filename *filename = getname_kernel(pathname); 3788b4a4f213SStephen Brennan struct dentry *res = filename_create(dfd, filename, path, lookup_flags); 3789b4a4f213SStephen Brennan 3790b4a4f213SStephen Brennan putname(filename); 3791b4a4f213SStephen Brennan return res; 3792fa14a0b8SAl Viro } 3793dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3794dae6ad8fSAl Viro 3795921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3796921a1650SAl Viro { 3797921a1650SAl Viro dput(dentry); 37985955102cSAl Viro inode_unlock(path->dentry->d_inode); 3799a8104a9fSAl Viro mnt_drop_write(path->mnt); 3800921a1650SAl Viro path_put(path); 3801921a1650SAl Viro } 3802921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3803921a1650SAl Viro 3804520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 38051ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3806dae6ad8fSAl Viro { 3807b4a4f213SStephen Brennan struct filename *filename = getname(pathname); 3808b4a4f213SStephen Brennan struct dentry *res = filename_create(dfd, filename, path, lookup_flags); 3809b4a4f213SStephen Brennan 3810b4a4f213SStephen Brennan putname(filename); 3811b4a4f213SStephen Brennan return res; 3812dae6ad8fSAl Viro } 3813dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3814dae6ad8fSAl Viro 38156521f891SChristian Brauner /** 38166521f891SChristian Brauner * vfs_mknod - create device node or file 38176521f891SChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 38186521f891SChristian Brauner * @dir: inode of @dentry 38196521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 38206521f891SChristian Brauner * @mode: mode of the new device node or file 38216521f891SChristian Brauner * @dev: device number of device to create 38226521f891SChristian Brauner * 38236521f891SChristian Brauner * Create a device node or file. 38246521f891SChristian Brauner * 38256521f891SChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 38266521f891SChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 38276521f891SChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 38286521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 38296521f891SChristian Brauner * raw inode simply passs init_user_ns. 38306521f891SChristian Brauner */ 38316521f891SChristian Brauner int vfs_mknod(struct user_namespace *mnt_userns, struct inode *dir, 38326521f891SChristian Brauner struct dentry *dentry, umode_t mode, dev_t dev) 38331da177e4SLinus Torvalds { 3834a3c751a5SMiklos Szeredi bool is_whiteout = S_ISCHR(mode) && dev == WHITEOUT_DEV; 38356521f891SChristian Brauner int error = may_create(mnt_userns, dir, dentry); 38361da177e4SLinus Torvalds 38371da177e4SLinus Torvalds if (error) 38381da177e4SLinus Torvalds return error; 38391da177e4SLinus Torvalds 3840a3c751a5SMiklos Szeredi if ((S_ISCHR(mode) || S_ISBLK(mode)) && !is_whiteout && 3841a3c751a5SMiklos Szeredi !capable(CAP_MKNOD)) 38421da177e4SLinus Torvalds return -EPERM; 38431da177e4SLinus Torvalds 3844acfa4380SAl Viro if (!dir->i_op->mknod) 38451da177e4SLinus Torvalds return -EPERM; 38461da177e4SLinus Torvalds 384708ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 384808ce5f16SSerge E. Hallyn if (error) 384908ce5f16SSerge E. Hallyn return error; 385008ce5f16SSerge E. Hallyn 38511da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 38521da177e4SLinus Torvalds if (error) 38531da177e4SLinus Torvalds return error; 38541da177e4SLinus Torvalds 3855549c7297SChristian Brauner error = dir->i_op->mknod(mnt_userns, dir, dentry, mode, dev); 3856a74574aaSStephen Smalley if (!error) 3857f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38581da177e4SLinus Torvalds return error; 38591da177e4SLinus Torvalds } 38604d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 38611da177e4SLinus Torvalds 3862f69aac00SAl Viro static int may_mknod(umode_t mode) 3863463c3197SDave Hansen { 3864463c3197SDave Hansen switch (mode & S_IFMT) { 3865463c3197SDave Hansen case S_IFREG: 3866463c3197SDave Hansen case S_IFCHR: 3867463c3197SDave Hansen case S_IFBLK: 3868463c3197SDave Hansen case S_IFIFO: 3869463c3197SDave Hansen case S_IFSOCK: 3870463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3871463c3197SDave Hansen return 0; 3872463c3197SDave Hansen case S_IFDIR: 3873463c3197SDave Hansen return -EPERM; 3874463c3197SDave Hansen default: 3875463c3197SDave Hansen return -EINVAL; 3876463c3197SDave Hansen } 3877463c3197SDave Hansen } 3878463c3197SDave Hansen 387945f30dabSDmitry Kadashev static int do_mknodat(int dfd, struct filename *name, umode_t mode, 388087c4e192SDominik Brodowski unsigned int dev) 38811da177e4SLinus Torvalds { 38826521f891SChristian Brauner struct user_namespace *mnt_userns; 38831da177e4SLinus Torvalds struct dentry *dentry; 3884dae6ad8fSAl Viro struct path path; 3885dae6ad8fSAl Viro int error; 3886972567f1SJeff Layton unsigned int lookup_flags = 0; 38871da177e4SLinus Torvalds 38888e4bfca1SAl Viro error = may_mknod(mode); 38898e4bfca1SAl Viro if (error) 38907797251bSDmitry Kadashev goto out1; 3891972567f1SJeff Layton retry: 3892b4a4f213SStephen Brennan dentry = filename_create(dfd, name, &path, lookup_flags); 38937797251bSDmitry Kadashev error = PTR_ERR(dentry); 3894dae6ad8fSAl Viro if (IS_ERR(dentry)) 38957797251bSDmitry Kadashev goto out1; 38962ad94ae6SAl Viro 3897dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3898ce3b0f8dSAl Viro mode &= ~current_umask(); 3899dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3900be6d3e56SKentaro Takeda if (error) 39017797251bSDmitry Kadashev goto out2; 39026521f891SChristian Brauner 39036521f891SChristian Brauner mnt_userns = mnt_user_ns(path.mnt); 39041da177e4SLinus Torvalds switch (mode & S_IFMT) { 39051da177e4SLinus Torvalds case 0: case S_IFREG: 39066521f891SChristian Brauner error = vfs_create(mnt_userns, path.dentry->d_inode, 39076521f891SChristian Brauner dentry, mode, true); 390805d1a717SMimi Zohar if (!error) 3909a2d2329eSChristian Brauner ima_post_path_mknod(mnt_userns, dentry); 39101da177e4SLinus Torvalds break; 39111da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 39126521f891SChristian Brauner error = vfs_mknod(mnt_userns, path.dentry->d_inode, 39136521f891SChristian Brauner dentry, mode, new_decode_dev(dev)); 39141da177e4SLinus Torvalds break; 39151da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 39166521f891SChristian Brauner error = vfs_mknod(mnt_userns, path.dentry->d_inode, 39176521f891SChristian Brauner dentry, mode, 0); 39181da177e4SLinus Torvalds break; 39191da177e4SLinus Torvalds } 39207797251bSDmitry Kadashev out2: 3921921a1650SAl Viro done_path_create(&path, dentry); 3922972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3923972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3924972567f1SJeff Layton goto retry; 3925972567f1SJeff Layton } 39267797251bSDmitry Kadashev out1: 39277797251bSDmitry Kadashev putname(name); 39281da177e4SLinus Torvalds return error; 39291da177e4SLinus Torvalds } 39301da177e4SLinus Torvalds 393187c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 393287c4e192SDominik Brodowski unsigned int, dev) 393387c4e192SDominik Brodowski { 39347797251bSDmitry Kadashev return do_mknodat(dfd, getname(filename), mode, dev); 393587c4e192SDominik Brodowski } 393687c4e192SDominik Brodowski 39378208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 39385590ff0dSUlrich Drepper { 39397797251bSDmitry Kadashev return do_mknodat(AT_FDCWD, getname(filename), mode, dev); 39405590ff0dSUlrich Drepper } 39415590ff0dSUlrich Drepper 39426521f891SChristian Brauner /** 39436521f891SChristian Brauner * vfs_mkdir - create directory 39446521f891SChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 39456521f891SChristian Brauner * @dir: inode of @dentry 39466521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 39476521f891SChristian Brauner * @mode: mode of the new directory 39486521f891SChristian Brauner * 39496521f891SChristian Brauner * Create a directory. 39506521f891SChristian Brauner * 39516521f891SChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 39526521f891SChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 39536521f891SChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 39546521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 39556521f891SChristian Brauner * raw inode simply passs init_user_ns. 39566521f891SChristian Brauner */ 39576521f891SChristian Brauner int vfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir, 39586521f891SChristian Brauner struct dentry *dentry, umode_t mode) 39591da177e4SLinus Torvalds { 39606521f891SChristian Brauner int error = may_create(mnt_userns, dir, dentry); 39618de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39621da177e4SLinus Torvalds 39631da177e4SLinus Torvalds if (error) 39641da177e4SLinus Torvalds return error; 39651da177e4SLinus Torvalds 3966acfa4380SAl Viro if (!dir->i_op->mkdir) 39671da177e4SLinus Torvalds return -EPERM; 39681da177e4SLinus Torvalds 39691da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 39701da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 39711da177e4SLinus Torvalds if (error) 39721da177e4SLinus Torvalds return error; 39731da177e4SLinus Torvalds 39748de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 39758de52778SAl Viro return -EMLINK; 39768de52778SAl Viro 3977549c7297SChristian Brauner error = dir->i_op->mkdir(mnt_userns, dir, dentry, mode); 3978a74574aaSStephen Smalley if (!error) 3979f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 39801da177e4SLinus Torvalds return error; 39811da177e4SLinus Torvalds } 39824d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 39831da177e4SLinus Torvalds 398445f30dabSDmitry Kadashev int do_mkdirat(int dfd, struct filename *name, umode_t mode) 39851da177e4SLinus Torvalds { 39866902d925SDave Hansen struct dentry *dentry; 3987dae6ad8fSAl Viro struct path path; 3988dae6ad8fSAl Viro int error; 3989b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 39901da177e4SLinus Torvalds 3991b76d8b82SJeff Layton retry: 3992b4a4f213SStephen Brennan dentry = filename_create(dfd, name, &path, lookup_flags); 3993584d3226SDmitry Kadashev error = PTR_ERR(dentry); 39946902d925SDave Hansen if (IS_ERR(dentry)) 3995584d3226SDmitry Kadashev goto out_putname; 39966902d925SDave Hansen 3997dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3998ce3b0f8dSAl Viro mode &= ~current_umask(); 3999dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 40006521f891SChristian Brauner if (!error) { 40016521f891SChristian Brauner struct user_namespace *mnt_userns; 40026521f891SChristian Brauner mnt_userns = mnt_user_ns(path.mnt); 4003549c7297SChristian Brauner error = vfs_mkdir(mnt_userns, path.dentry->d_inode, dentry, 4004549c7297SChristian Brauner mode); 40056521f891SChristian Brauner } 4006921a1650SAl Viro done_path_create(&path, dentry); 4007b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 4008b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 4009b76d8b82SJeff Layton goto retry; 4010b76d8b82SJeff Layton } 4011584d3226SDmitry Kadashev out_putname: 4012584d3226SDmitry Kadashev putname(name); 40131da177e4SLinus Torvalds return error; 40141da177e4SLinus Torvalds } 40151da177e4SLinus Torvalds 40160101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 40170101db7aSDominik Brodowski { 4018584d3226SDmitry Kadashev return do_mkdirat(dfd, getname(pathname), mode); 40190101db7aSDominik Brodowski } 40200101db7aSDominik Brodowski 4021a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 40225590ff0dSUlrich Drepper { 4023584d3226SDmitry Kadashev return do_mkdirat(AT_FDCWD, getname(pathname), mode); 40245590ff0dSUlrich Drepper } 40255590ff0dSUlrich Drepper 40266521f891SChristian Brauner /** 40276521f891SChristian Brauner * vfs_rmdir - remove directory 40286521f891SChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 40296521f891SChristian Brauner * @dir: inode of @dentry 40306521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 40316521f891SChristian Brauner * 40326521f891SChristian Brauner * Remove a directory. 40336521f891SChristian Brauner * 40346521f891SChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 40356521f891SChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 40366521f891SChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 40376521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 40386521f891SChristian Brauner * raw inode simply passs init_user_ns. 40396521f891SChristian Brauner */ 40406521f891SChristian Brauner int vfs_rmdir(struct user_namespace *mnt_userns, struct inode *dir, 40416521f891SChristian Brauner struct dentry *dentry) 40421da177e4SLinus Torvalds { 40436521f891SChristian Brauner int error = may_delete(mnt_userns, dir, dentry, 1); 40441da177e4SLinus Torvalds 40451da177e4SLinus Torvalds if (error) 40461da177e4SLinus Torvalds return error; 40471da177e4SLinus Torvalds 4048acfa4380SAl Viro if (!dir->i_op->rmdir) 40491da177e4SLinus Torvalds return -EPERM; 40501da177e4SLinus Torvalds 40511d2ef590SAl Viro dget(dentry); 40525955102cSAl Viro inode_lock(dentry->d_inode); 4053912dbc15SSage Weil 40541da177e4SLinus Torvalds error = -EBUSY; 40551bd9c4e4SDavid Howells if (is_local_mountpoint(dentry) || 40561bd9c4e4SDavid Howells (dentry->d_inode->i_flags & S_KERNEL_FILE)) 4057912dbc15SSage Weil goto out; 4058912dbc15SSage Weil 40591da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 4060912dbc15SSage Weil if (error) 4061912dbc15SSage Weil goto out; 4062912dbc15SSage Weil 40631da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 4064912dbc15SSage Weil if (error) 4065912dbc15SSage Weil goto out; 4066912dbc15SSage Weil 40678767712fSAl Viro shrink_dcache_parent(dentry); 40681da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 4069d83c49f3SAl Viro dont_mount(dentry); 40708ed936b5SEric W. Biederman detach_mounts(dentry); 40711da177e4SLinus Torvalds 4072912dbc15SSage Weil out: 40735955102cSAl Viro inode_unlock(dentry->d_inode); 40741d2ef590SAl Viro dput(dentry); 4075912dbc15SSage Weil if (!error) 4076a37d9a17SAmir Goldstein d_delete_notify(dir, dentry); 40771da177e4SLinus Torvalds return error; 40781da177e4SLinus Torvalds } 40794d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 40801da177e4SLinus Torvalds 408145f30dabSDmitry Kadashev int do_rmdir(int dfd, struct filename *name) 40821da177e4SLinus Torvalds { 40836521f891SChristian Brauner struct user_namespace *mnt_userns; 40840ee50b47SDmitry Kadashev int error; 40851da177e4SLinus Torvalds struct dentry *dentry; 4086f5beed75SAl Viro struct path path; 4087f5beed75SAl Viro struct qstr last; 4088f5beed75SAl Viro int type; 4089c6ee9206SJeff Layton unsigned int lookup_flags = 0; 4090c6ee9206SJeff Layton retry: 4091c5f563f9SAl Viro error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 40920ee50b47SDmitry Kadashev if (error) 40930ee50b47SDmitry Kadashev goto exit1; 40941da177e4SLinus Torvalds 4095f5beed75SAl Viro switch (type) { 40961da177e4SLinus Torvalds case LAST_DOTDOT: 40971da177e4SLinus Torvalds error = -ENOTEMPTY; 40980ee50b47SDmitry Kadashev goto exit2; 40991da177e4SLinus Torvalds case LAST_DOT: 41001da177e4SLinus Torvalds error = -EINVAL; 41010ee50b47SDmitry Kadashev goto exit2; 41021da177e4SLinus Torvalds case LAST_ROOT: 41031da177e4SLinus Torvalds error = -EBUSY; 41040ee50b47SDmitry Kadashev goto exit2; 41051da177e4SLinus Torvalds } 41060612d9fbSOGAWA Hirofumi 4107f5beed75SAl Viro error = mnt_want_write(path.mnt); 4108c30dabfeSJan Kara if (error) 41090ee50b47SDmitry Kadashev goto exit2; 41100612d9fbSOGAWA Hirofumi 41115955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4112f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 41131da177e4SLinus Torvalds error = PTR_ERR(dentry); 41146902d925SDave Hansen if (IS_ERR(dentry)) 41150ee50b47SDmitry Kadashev goto exit3; 4116e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 4117e6bc45d6STheodore Ts'o error = -ENOENT; 41180ee50b47SDmitry Kadashev goto exit4; 4119e6bc45d6STheodore Ts'o } 4120f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 4121be6d3e56SKentaro Takeda if (error) 41220ee50b47SDmitry Kadashev goto exit4; 41236521f891SChristian Brauner mnt_userns = mnt_user_ns(path.mnt); 41246521f891SChristian Brauner error = vfs_rmdir(mnt_userns, path.dentry->d_inode, dentry); 41250ee50b47SDmitry Kadashev exit4: 41261da177e4SLinus Torvalds dput(dentry); 41270ee50b47SDmitry Kadashev exit3: 41285955102cSAl Viro inode_unlock(path.dentry->d_inode); 4129f5beed75SAl Viro mnt_drop_write(path.mnt); 41300ee50b47SDmitry Kadashev exit2: 4131f5beed75SAl Viro path_put(&path); 4132c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 4133c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 4134c6ee9206SJeff Layton goto retry; 4135c6ee9206SJeff Layton } 41360ee50b47SDmitry Kadashev exit1: 413724fb33d4SAl Viro putname(name); 41381da177e4SLinus Torvalds return error; 41391da177e4SLinus Torvalds } 41401da177e4SLinus Torvalds 41413cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 41425590ff0dSUlrich Drepper { 4143e24ab0efSChristoph Hellwig return do_rmdir(AT_FDCWD, getname(pathname)); 41445590ff0dSUlrich Drepper } 41455590ff0dSUlrich Drepper 4146b21996e3SJ. Bruce Fields /** 4147b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 41486521f891SChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 4149b21996e3SJ. Bruce Fields * @dir: parent directory 4150b21996e3SJ. Bruce Fields * @dentry: victim 4151b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 4152b21996e3SJ. Bruce Fields * 4153b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 4154b21996e3SJ. Bruce Fields * 4155b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 4156b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 4157b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 4158b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 4159b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 4160b21996e3SJ. Bruce Fields * 4161b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4162b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4163b21996e3SJ. Bruce Fields * to be NFS exported. 41646521f891SChristian Brauner * 41656521f891SChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 41666521f891SChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 41676521f891SChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 41686521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 41696521f891SChristian Brauner * raw inode simply passs init_user_ns. 4170b21996e3SJ. Bruce Fields */ 41716521f891SChristian Brauner int vfs_unlink(struct user_namespace *mnt_userns, struct inode *dir, 41726521f891SChristian Brauner struct dentry *dentry, struct inode **delegated_inode) 41731da177e4SLinus Torvalds { 41749accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 41756521f891SChristian Brauner int error = may_delete(mnt_userns, dir, dentry, 0); 41761da177e4SLinus Torvalds 41771da177e4SLinus Torvalds if (error) 41781da177e4SLinus Torvalds return error; 41791da177e4SLinus Torvalds 4180acfa4380SAl Viro if (!dir->i_op->unlink) 41811da177e4SLinus Torvalds return -EPERM; 41821da177e4SLinus Torvalds 41835955102cSAl Viro inode_lock(target); 418451cc3a66SHugh Dickins if (IS_SWAPFILE(target)) 418551cc3a66SHugh Dickins error = -EPERM; 418651cc3a66SHugh Dickins else if (is_local_mountpoint(dentry)) 41871da177e4SLinus Torvalds error = -EBUSY; 41881da177e4SLinus Torvalds else { 41891da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 4190bec1052eSAl Viro if (!error) { 41915a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 41925a14696cSJ. Bruce Fields if (error) 4193b21996e3SJ. Bruce Fields goto out; 41941da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 41958ed936b5SEric W. Biederman if (!error) { 4196d83c49f3SAl Viro dont_mount(dentry); 41978ed936b5SEric W. Biederman detach_mounts(dentry); 41988ed936b5SEric W. Biederman } 4199bec1052eSAl Viro } 42001da177e4SLinus Torvalds } 4201b21996e3SJ. Bruce Fields out: 42025955102cSAl Viro inode_unlock(target); 42031da177e4SLinus Torvalds 42041da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 4205a37d9a17SAmir Goldstein if (!error && dentry->d_flags & DCACHE_NFSFS_RENAMED) { 4206a37d9a17SAmir Goldstein fsnotify_unlink(dir, dentry); 4207a37d9a17SAmir Goldstein } else if (!error) { 42089accbb97SJ. Bruce Fields fsnotify_link_count(target); 4209a37d9a17SAmir Goldstein d_delete_notify(dir, dentry); 42101da177e4SLinus Torvalds } 42110eeca283SRobert Love 42121da177e4SLinus Torvalds return error; 42131da177e4SLinus Torvalds } 42144d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 42151da177e4SLinus Torvalds 42161da177e4SLinus Torvalds /* 42171da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 42181b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 42191da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 42201da177e4SLinus Torvalds * while waiting on the I/O. 42211da177e4SLinus Torvalds */ 422245f30dabSDmitry Kadashev int do_unlinkat(int dfd, struct filename *name) 42231da177e4SLinus Torvalds { 42242ad94ae6SAl Viro int error; 42251da177e4SLinus Torvalds struct dentry *dentry; 4226f5beed75SAl Viro struct path path; 4227f5beed75SAl Viro struct qstr last; 4228f5beed75SAl Viro int type; 42291da177e4SLinus Torvalds struct inode *inode = NULL; 4230b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 42315d18f813SJeff Layton unsigned int lookup_flags = 0; 42325d18f813SJeff Layton retry: 4233c5f563f9SAl Viro error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 42340ee50b47SDmitry Kadashev if (error) 42350ee50b47SDmitry Kadashev goto exit1; 42362ad94ae6SAl Viro 42371da177e4SLinus Torvalds error = -EISDIR; 4238f5beed75SAl Viro if (type != LAST_NORM) 42390ee50b47SDmitry Kadashev goto exit2; 42400612d9fbSOGAWA Hirofumi 4241f5beed75SAl Viro error = mnt_want_write(path.mnt); 4242c30dabfeSJan Kara if (error) 42430ee50b47SDmitry Kadashev goto exit2; 4244b21996e3SJ. Bruce Fields retry_deleg: 42455955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4246f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 42471da177e4SLinus Torvalds error = PTR_ERR(dentry); 42481da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 42496521f891SChristian Brauner struct user_namespace *mnt_userns; 42506521f891SChristian Brauner 42511da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4252f5beed75SAl Viro if (last.name[last.len]) 425350338b88STörök Edwin goto slashes; 42541da177e4SLinus Torvalds inode = dentry->d_inode; 4255b18825a7SDavid Howells if (d_is_negative(dentry)) 4256e6bc45d6STheodore Ts'o goto slashes; 42577de9c6eeSAl Viro ihold(inode); 4258f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4259be6d3e56SKentaro Takeda if (error) 42600ee50b47SDmitry Kadashev goto exit3; 42616521f891SChristian Brauner mnt_userns = mnt_user_ns(path.mnt); 4262549c7297SChristian Brauner error = vfs_unlink(mnt_userns, path.dentry->d_inode, dentry, 4263549c7297SChristian Brauner &delegated_inode); 42640ee50b47SDmitry Kadashev exit3: 42651da177e4SLinus Torvalds dput(dentry); 42661da177e4SLinus Torvalds } 42675955102cSAl Viro inode_unlock(path.dentry->d_inode); 42681da177e4SLinus Torvalds if (inode) 42691da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4270b21996e3SJ. Bruce Fields inode = NULL; 4271b21996e3SJ. Bruce Fields if (delegated_inode) { 42725a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4273b21996e3SJ. Bruce Fields if (!error) 4274b21996e3SJ. Bruce Fields goto retry_deleg; 4275b21996e3SJ. Bruce Fields } 4276f5beed75SAl Viro mnt_drop_write(path.mnt); 42770ee50b47SDmitry Kadashev exit2: 4278f5beed75SAl Viro path_put(&path); 42795d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 42805d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 42815d18f813SJeff Layton inode = NULL; 42825d18f813SJeff Layton goto retry; 42835d18f813SJeff Layton } 42840ee50b47SDmitry Kadashev exit1: 4285da2f1362SChristoph Hellwig putname(name); 42861da177e4SLinus Torvalds return error; 42871da177e4SLinus Torvalds 42881da177e4SLinus Torvalds slashes: 4289b18825a7SDavid Howells if (d_is_negative(dentry)) 4290b18825a7SDavid Howells error = -ENOENT; 429144b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4292b18825a7SDavid Howells error = -EISDIR; 4293b18825a7SDavid Howells else 4294b18825a7SDavid Howells error = -ENOTDIR; 42950ee50b47SDmitry Kadashev goto exit3; 42961da177e4SLinus Torvalds } 42971da177e4SLinus Torvalds 42982e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 42995590ff0dSUlrich Drepper { 43005590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 43015590ff0dSUlrich Drepper return -EINVAL; 43025590ff0dSUlrich Drepper 43035590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 4304e24ab0efSChristoph Hellwig return do_rmdir(dfd, getname(pathname)); 4305da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 43065590ff0dSUlrich Drepper } 43075590ff0dSUlrich Drepper 43083480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 43095590ff0dSUlrich Drepper { 4310da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 43115590ff0dSUlrich Drepper } 43125590ff0dSUlrich Drepper 43136521f891SChristian Brauner /** 43146521f891SChristian Brauner * vfs_symlink - create symlink 43156521f891SChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 43166521f891SChristian Brauner * @dir: inode of @dentry 43176521f891SChristian Brauner * @dentry: pointer to dentry of the base directory 43186521f891SChristian Brauner * @oldname: name of the file to link to 43196521f891SChristian Brauner * 43206521f891SChristian Brauner * Create a symlink. 43216521f891SChristian Brauner * 43226521f891SChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 43236521f891SChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 43246521f891SChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 43256521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 43266521f891SChristian Brauner * raw inode simply passs init_user_ns. 43276521f891SChristian Brauner */ 43286521f891SChristian Brauner int vfs_symlink(struct user_namespace *mnt_userns, struct inode *dir, 43296521f891SChristian Brauner struct dentry *dentry, const char *oldname) 43301da177e4SLinus Torvalds { 43316521f891SChristian Brauner int error = may_create(mnt_userns, dir, dentry); 43321da177e4SLinus Torvalds 43331da177e4SLinus Torvalds if (error) 43341da177e4SLinus Torvalds return error; 43351da177e4SLinus Torvalds 4336acfa4380SAl Viro if (!dir->i_op->symlink) 43371da177e4SLinus Torvalds return -EPERM; 43381da177e4SLinus Torvalds 43391da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 43401da177e4SLinus Torvalds if (error) 43411da177e4SLinus Torvalds return error; 43421da177e4SLinus Torvalds 4343549c7297SChristian Brauner error = dir->i_op->symlink(mnt_userns, dir, dentry, oldname); 4344a74574aaSStephen Smalley if (!error) 4345f38aa942SAmy Griffis fsnotify_create(dir, dentry); 43461da177e4SLinus Torvalds return error; 43471da177e4SLinus Torvalds } 43484d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 43491da177e4SLinus Torvalds 43507a8721f8SDmitry Kadashev int do_symlinkat(struct filename *from, int newdfd, struct filename *to) 43511da177e4SLinus Torvalds { 43522ad94ae6SAl Viro int error; 43536902d925SDave Hansen struct dentry *dentry; 4354dae6ad8fSAl Viro struct path path; 4355f46d3567SJeff Layton unsigned int lookup_flags = 0; 43561da177e4SLinus Torvalds 4357da2d0cedSDmitry Kadashev if (IS_ERR(from)) { 4358da2d0cedSDmitry Kadashev error = PTR_ERR(from); 4359da2d0cedSDmitry Kadashev goto out_putnames; 4360da2d0cedSDmitry Kadashev } 4361f46d3567SJeff Layton retry: 4362b4a4f213SStephen Brennan dentry = filename_create(newdfd, to, &path, lookup_flags); 43631da177e4SLinus Torvalds error = PTR_ERR(dentry); 43646902d925SDave Hansen if (IS_ERR(dentry)) 4365da2d0cedSDmitry Kadashev goto out_putnames; 43666902d925SDave Hansen 436791a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 43686521f891SChristian Brauner if (!error) { 43696521f891SChristian Brauner struct user_namespace *mnt_userns; 43706521f891SChristian Brauner 43716521f891SChristian Brauner mnt_userns = mnt_user_ns(path.mnt); 43726521f891SChristian Brauner error = vfs_symlink(mnt_userns, path.dentry->d_inode, dentry, 43736521f891SChristian Brauner from->name); 43746521f891SChristian Brauner } 4375921a1650SAl Viro done_path_create(&path, dentry); 4376f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4377f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4378f46d3567SJeff Layton goto retry; 4379f46d3567SJeff Layton } 4380da2d0cedSDmitry Kadashev out_putnames: 4381da2d0cedSDmitry Kadashev putname(to); 43821da177e4SLinus Torvalds putname(from); 43831da177e4SLinus Torvalds return error; 43841da177e4SLinus Torvalds } 43851da177e4SLinus Torvalds 4386b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4387b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4388b724e846SDominik Brodowski { 4389da2d0cedSDmitry Kadashev return do_symlinkat(getname(oldname), newdfd, getname(newname)); 4390b724e846SDominik Brodowski } 4391b724e846SDominik Brodowski 43923480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 43935590ff0dSUlrich Drepper { 4394da2d0cedSDmitry Kadashev return do_symlinkat(getname(oldname), AT_FDCWD, getname(newname)); 43955590ff0dSUlrich Drepper } 43965590ff0dSUlrich Drepper 4397146a8595SJ. Bruce Fields /** 4398146a8595SJ. Bruce Fields * vfs_link - create a new link 4399146a8595SJ. Bruce Fields * @old_dentry: object to be linked 44006521f891SChristian Brauner * @mnt_userns: the user namespace of the mount 4401146a8595SJ. Bruce Fields * @dir: new parent 4402146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4403146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4404146a8595SJ. Bruce Fields * 4405146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4406146a8595SJ. Bruce Fields * 4407146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4408146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4409146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4410146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4411146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4412146a8595SJ. Bruce Fields * 4413146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4414146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4415146a8595SJ. Bruce Fields * to be NFS exported. 44166521f891SChristian Brauner * 44176521f891SChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 44186521f891SChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 44196521f891SChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 44206521f891SChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 44216521f891SChristian Brauner * raw inode simply passs init_user_ns. 4422146a8595SJ. Bruce Fields */ 44236521f891SChristian Brauner int vfs_link(struct dentry *old_dentry, struct user_namespace *mnt_userns, 44246521f891SChristian Brauner struct inode *dir, struct dentry *new_dentry, 44256521f891SChristian Brauner struct inode **delegated_inode) 44261da177e4SLinus Torvalds { 44271da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 44288de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 44291da177e4SLinus Torvalds int error; 44301da177e4SLinus Torvalds 44311da177e4SLinus Torvalds if (!inode) 44321da177e4SLinus Torvalds return -ENOENT; 44331da177e4SLinus Torvalds 44346521f891SChristian Brauner error = may_create(mnt_userns, dir, new_dentry); 44351da177e4SLinus Torvalds if (error) 44361da177e4SLinus Torvalds return error; 44371da177e4SLinus Torvalds 44381da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 44391da177e4SLinus Torvalds return -EXDEV; 44401da177e4SLinus Torvalds 44411da177e4SLinus Torvalds /* 44421da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 44431da177e4SLinus Torvalds */ 44441da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 44451da177e4SLinus Torvalds return -EPERM; 44460bd23d09SEric W. Biederman /* 44470bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 44480bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 44490bd23d09SEric W. Biederman * the vfs. 44500bd23d09SEric W. Biederman */ 44516521f891SChristian Brauner if (HAS_UNMAPPED_ID(mnt_userns, inode)) 44520bd23d09SEric W. Biederman return -EPERM; 4453acfa4380SAl Viro if (!dir->i_op->link) 44541da177e4SLinus Torvalds return -EPERM; 44557e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 44561da177e4SLinus Torvalds return -EPERM; 44571da177e4SLinus Torvalds 44581da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 44591da177e4SLinus Torvalds if (error) 44601da177e4SLinus Torvalds return error; 44611da177e4SLinus Torvalds 44625955102cSAl Viro inode_lock(inode); 4463aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4464f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4465aae8a97dSAneesh Kumar K.V error = -ENOENT; 44668de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 44678de52778SAl Viro error = -EMLINK; 4468146a8595SJ. Bruce Fields else { 4469146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4470146a8595SJ. Bruce Fields if (!error) 44711da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4472146a8595SJ. Bruce Fields } 4473f4e0c30cSAl Viro 4474f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4475f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4476f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4477f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4478f4e0c30cSAl Viro } 44795955102cSAl Viro inode_unlock(inode); 4480e31e14ecSStephen Smalley if (!error) 44817e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 44821da177e4SLinus Torvalds return error; 44831da177e4SLinus Torvalds } 44844d359507SAl Viro EXPORT_SYMBOL(vfs_link); 44851da177e4SLinus Torvalds 44861da177e4SLinus Torvalds /* 44871da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 44881da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 44891da177e4SLinus Torvalds * newname. --KAB 44901da177e4SLinus Torvalds * 44911da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 44921da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 44931da177e4SLinus Torvalds * and other special files. --ADM 44941da177e4SLinus Torvalds */ 4495cf30da90SDmitry Kadashev int do_linkat(int olddfd, struct filename *old, int newdfd, 4496020250f3SDmitry Kadashev struct filename *new, int flags) 44971da177e4SLinus Torvalds { 44986521f891SChristian Brauner struct user_namespace *mnt_userns; 44991da177e4SLinus Torvalds struct dentry *new_dentry; 4500dae6ad8fSAl Viro struct path old_path, new_path; 4501146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 450211a7b371SAneesh Kumar K.V int how = 0; 45031da177e4SLinus Torvalds int error; 45041da177e4SLinus Torvalds 4505020250f3SDmitry Kadashev if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) { 4506020250f3SDmitry Kadashev error = -EINVAL; 4507020250f3SDmitry Kadashev goto out_putnames; 4508020250f3SDmitry Kadashev } 450911a7b371SAneesh Kumar K.V /* 4510f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4511f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4512f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 451311a7b371SAneesh Kumar K.V */ 4514020250f3SDmitry Kadashev if (flags & AT_EMPTY_PATH && !capable(CAP_DAC_READ_SEARCH)) { 4515020250f3SDmitry Kadashev error = -ENOENT; 4516020250f3SDmitry Kadashev goto out_putnames; 4517f0cc6ffbSLinus Torvalds } 4518c04030e1SUlrich Drepper 451911a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 452011a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4521442e31caSJeff Layton retry: 4522794ebceaSStephen Brennan error = filename_lookup(olddfd, old, how, &old_path, NULL); 45231da177e4SLinus Torvalds if (error) 4524020250f3SDmitry Kadashev goto out_putnames; 45252ad94ae6SAl Viro 4526b4a4f213SStephen Brennan new_dentry = filename_create(newdfd, new, &new_path, 4527442e31caSJeff Layton (how & LOOKUP_REVAL)); 45281da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45296902d925SDave Hansen if (IS_ERR(new_dentry)) 4530020250f3SDmitry Kadashev goto out_putpath; 4531dae6ad8fSAl Viro 4532dae6ad8fSAl Viro error = -EXDEV; 4533dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4534dae6ad8fSAl Viro goto out_dput; 4535549c7297SChristian Brauner mnt_userns = mnt_user_ns(new_path.mnt); 4536549c7297SChristian Brauner error = may_linkat(mnt_userns, &old_path); 4537800179c9SKees Cook if (unlikely(error)) 4538800179c9SKees Cook goto out_dput; 4539dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4540be6d3e56SKentaro Takeda if (error) 4541a8104a9fSAl Viro goto out_dput; 45426521f891SChristian Brauner error = vfs_link(old_path.dentry, mnt_userns, new_path.dentry->d_inode, 45436521f891SChristian Brauner new_dentry, &delegated_inode); 454475c3f29dSDave Hansen out_dput: 4545921a1650SAl Viro done_path_create(&new_path, new_dentry); 4546146a8595SJ. Bruce Fields if (delegated_inode) { 4547146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4548d22e6338SOleg Drokin if (!error) { 4549d22e6338SOleg Drokin path_put(&old_path); 4550146a8595SJ. Bruce Fields goto retry; 4551146a8595SJ. Bruce Fields } 4552d22e6338SOleg Drokin } 4553442e31caSJeff Layton if (retry_estale(error, how)) { 4554d22e6338SOleg Drokin path_put(&old_path); 4555442e31caSJeff Layton how |= LOOKUP_REVAL; 4556442e31caSJeff Layton goto retry; 4557442e31caSJeff Layton } 4558020250f3SDmitry Kadashev out_putpath: 45592d8f3038SAl Viro path_put(&old_path); 4560020250f3SDmitry Kadashev out_putnames: 4561020250f3SDmitry Kadashev putname(old); 4562020250f3SDmitry Kadashev putname(new); 45631da177e4SLinus Torvalds 45641da177e4SLinus Torvalds return error; 45651da177e4SLinus Torvalds } 45661da177e4SLinus Torvalds 456746ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 456846ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 456946ea89ebSDominik Brodowski { 4570020250f3SDmitry Kadashev return do_linkat(olddfd, getname_uflags(oldname, flags), 4571020250f3SDmitry Kadashev newdfd, getname(newname), flags); 457246ea89ebSDominik Brodowski } 457346ea89ebSDominik Brodowski 45743480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 45755590ff0dSUlrich Drepper { 4576020250f3SDmitry Kadashev return do_linkat(AT_FDCWD, getname(oldname), AT_FDCWD, getname(newname), 0); 45775590ff0dSUlrich Drepper } 45785590ff0dSUlrich Drepper 4579bc27027aSMiklos Szeredi /** 4580bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 45812111c3c0SRandy Dunlap * @rd: pointer to &struct renamedata info 4582bc27027aSMiklos Szeredi * 4583bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4584bc27027aSMiklos Szeredi * 4585bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4586bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4587bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4588bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4589bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4590bc27027aSMiklos Szeredi * so. 4591bc27027aSMiklos Szeredi * 4592bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4593bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4594bc27027aSMiklos Szeredi * to be NFS exported. 4595bc27027aSMiklos Szeredi * 45961da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 45971da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 45981da177e4SLinus Torvalds * Problems: 45990117d427SMauro Carvalho Chehab * 4600d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 46011da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 46021da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4603a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 46041da177e4SLinus Torvalds * story. 46056cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 46066cedba89SJ. Bruce Fields * and source (if it is not a directory). 46071b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 46081da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 46091da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4610a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 46111da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 46121da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 46131da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4614a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 46151da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 46161da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 46171da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4618e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 46191b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 46201da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4621c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 46221da177e4SLinus Torvalds * locking]. 46231da177e4SLinus Torvalds */ 46249fe61450SChristian Brauner int vfs_rename(struct renamedata *rd) 46251da177e4SLinus Torvalds { 46261da177e4SLinus Torvalds int error; 46279fe61450SChristian Brauner struct inode *old_dir = rd->old_dir, *new_dir = rd->new_dir; 46289fe61450SChristian Brauner struct dentry *old_dentry = rd->old_dentry; 46299fe61450SChristian Brauner struct dentry *new_dentry = rd->new_dentry; 46309fe61450SChristian Brauner struct inode **delegated_inode = rd->delegated_inode; 46319fe61450SChristian Brauner unsigned int flags = rd->flags; 4632bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4633bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4634bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4635da1ce067SMiklos Szeredi bool new_is_dir = false; 4636da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 463749d31c2fSAl Viro struct name_snapshot old_name; 46381da177e4SLinus Torvalds 46398d3e2936SMiklos Szeredi if (source == target) 46401da177e4SLinus Torvalds return 0; 46411da177e4SLinus Torvalds 46426521f891SChristian Brauner error = may_delete(rd->old_mnt_userns, old_dir, old_dentry, is_dir); 46431da177e4SLinus Torvalds if (error) 46441da177e4SLinus Torvalds return error; 46451da177e4SLinus Torvalds 4646da1ce067SMiklos Szeredi if (!target) { 46476521f891SChristian Brauner error = may_create(rd->new_mnt_userns, new_dir, new_dentry); 4648da1ce067SMiklos Szeredi } else { 4649da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4650da1ce067SMiklos Szeredi 4651da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 46526521f891SChristian Brauner error = may_delete(rd->new_mnt_userns, new_dir, 46536521f891SChristian Brauner new_dentry, is_dir); 4654da1ce067SMiklos Szeredi else 46556521f891SChristian Brauner error = may_delete(rd->new_mnt_userns, new_dir, 46566521f891SChristian Brauner new_dentry, new_is_dir); 4657da1ce067SMiklos Szeredi } 46581da177e4SLinus Torvalds if (error) 46591da177e4SLinus Torvalds return error; 46601da177e4SLinus Torvalds 46612773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 46621da177e4SLinus Torvalds return -EPERM; 46631da177e4SLinus Torvalds 4664bc27027aSMiklos Szeredi /* 4665bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4666bc27027aSMiklos Szeredi * we'll need to flip '..'. 4667bc27027aSMiklos Szeredi */ 4668da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4669da1ce067SMiklos Szeredi if (is_dir) { 46706521f891SChristian Brauner error = inode_permission(rd->old_mnt_userns, source, 467147291baaSChristian Brauner MAY_WRITE); 4672bc27027aSMiklos Szeredi if (error) 4673bc27027aSMiklos Szeredi return error; 4674bc27027aSMiklos Szeredi } 4675da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 46766521f891SChristian Brauner error = inode_permission(rd->new_mnt_userns, target, 467747291baaSChristian Brauner MAY_WRITE); 4678da1ce067SMiklos Szeredi if (error) 4679da1ce067SMiklos Szeredi return error; 4680da1ce067SMiklos Szeredi } 4681da1ce067SMiklos Szeredi } 46820eeca283SRobert Love 46830b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 46840b3974ebSMiklos Szeredi flags); 4685bc27027aSMiklos Szeredi if (error) 4686bc27027aSMiklos Szeredi return error; 4687bc27027aSMiklos Szeredi 468849d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4689bc27027aSMiklos Szeredi dget(new_dentry); 4690da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4691bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4692bc27027aSMiklos Szeredi else if (target) 46935955102cSAl Viro inode_lock(target); 4694bc27027aSMiklos Szeredi 469551cc3a66SHugh Dickins error = -EPERM; 469651cc3a66SHugh Dickins if (IS_SWAPFILE(source) || (target && IS_SWAPFILE(target))) 469751cc3a66SHugh Dickins goto out; 469851cc3a66SHugh Dickins 4699bc27027aSMiklos Szeredi error = -EBUSY; 47007af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4701bc27027aSMiklos Szeredi goto out; 4702bc27027aSMiklos Szeredi 4703da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4704bc27027aSMiklos Szeredi error = -EMLINK; 4705da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4706bc27027aSMiklos Szeredi goto out; 4707da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4708da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4709da1ce067SMiklos Szeredi goto out; 4710da1ce067SMiklos Szeredi } 4711da1ce067SMiklos Szeredi if (!is_dir) { 4712bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4713bc27027aSMiklos Szeredi if (error) 4714bc27027aSMiklos Szeredi goto out; 4715da1ce067SMiklos Szeredi } 4716da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4717bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4718bc27027aSMiklos Szeredi if (error) 4719bc27027aSMiklos Szeredi goto out; 4720bc27027aSMiklos Szeredi } 4721549c7297SChristian Brauner error = old_dir->i_op->rename(rd->new_mnt_userns, old_dir, old_dentry, 4722520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4723bc27027aSMiklos Szeredi if (error) 4724bc27027aSMiklos Szeredi goto out; 4725bc27027aSMiklos Szeredi 4726da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 47278767712fSAl Viro if (is_dir) { 47288767712fSAl Viro shrink_dcache_parent(new_dentry); 4729bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 47308767712fSAl Viro } 4731bc27027aSMiklos Szeredi dont_mount(new_dentry); 47328ed936b5SEric W. Biederman detach_mounts(new_dentry); 4733bc27027aSMiklos Szeredi } 4734da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4735da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4736bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4737da1ce067SMiklos Szeredi else 4738da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4739da1ce067SMiklos Szeredi } 4740bc27027aSMiklos Szeredi out: 4741da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4742bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4743bc27027aSMiklos Szeredi else if (target) 47445955102cSAl Viro inode_unlock(target); 4745bc27027aSMiklos Szeredi dput(new_dentry); 4746da1ce067SMiklos Szeredi if (!error) { 4747f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4748da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4749da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4750f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4751da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4752da1ce067SMiklos Szeredi } 4753da1ce067SMiklos Szeredi } 475449d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 47550eeca283SRobert Love 47561da177e4SLinus Torvalds return error; 47571da177e4SLinus Torvalds } 47584d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 47591da177e4SLinus Torvalds 4760e886663cSJens Axboe int do_renameat2(int olddfd, struct filename *from, int newdfd, 4761e886663cSJens Axboe struct filename *to, unsigned int flags) 47621da177e4SLinus Torvalds { 47639fe61450SChristian Brauner struct renamedata rd; 47641da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 47651da177e4SLinus Torvalds struct dentry *trap; 4766f5beed75SAl Viro struct path old_path, new_path; 4767f5beed75SAl Viro struct qstr old_last, new_last; 4768f5beed75SAl Viro int old_type, new_type; 47698e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 4770f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4771c6a94284SJeff Layton bool should_retry = false; 4772e886663cSJens Axboe int error = -EINVAL; 4773520c8b16SMiklos Szeredi 47740d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 47750ee50b47SDmitry Kadashev goto put_names; 4776da1ce067SMiklos Szeredi 47770d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 47780d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 47790ee50b47SDmitry Kadashev goto put_names; 4780520c8b16SMiklos Szeredi 4781f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4782f5beed75SAl Viro target_flags = 0; 4783f5beed75SAl Viro 4784c6a94284SJeff Layton retry: 4785c5f563f9SAl Viro error = filename_parentat(olddfd, from, lookup_flags, &old_path, 4786e886663cSJens Axboe &old_last, &old_type); 47870ee50b47SDmitry Kadashev if (error) 47880ee50b47SDmitry Kadashev goto put_names; 47891da177e4SLinus Torvalds 4790c5f563f9SAl Viro error = filename_parentat(newdfd, to, lookup_flags, &new_path, &new_last, 4791e886663cSJens Axboe &new_type); 47920ee50b47SDmitry Kadashev if (error) 47931da177e4SLinus Torvalds goto exit1; 47941da177e4SLinus Torvalds 47951da177e4SLinus Torvalds error = -EXDEV; 4796f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 47971da177e4SLinus Torvalds goto exit2; 47981da177e4SLinus Torvalds 47991da177e4SLinus Torvalds error = -EBUSY; 4800f5beed75SAl Viro if (old_type != LAST_NORM) 48011da177e4SLinus Torvalds goto exit2; 48021da177e4SLinus Torvalds 48030a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 48040a7c3937SMiklos Szeredi error = -EEXIST; 4805f5beed75SAl Viro if (new_type != LAST_NORM) 48061da177e4SLinus Torvalds goto exit2; 48071da177e4SLinus Torvalds 4808f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4809c30dabfeSJan Kara if (error) 4810c30dabfeSJan Kara goto exit2; 4811c30dabfeSJan Kara 48128e6d782cSJ. Bruce Fields retry_deleg: 4813f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 48141da177e4SLinus Torvalds 4815f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 48161da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 48171da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 48181da177e4SLinus Torvalds goto exit3; 48191da177e4SLinus Torvalds /* source must exist */ 48201da177e4SLinus Torvalds error = -ENOENT; 4821b18825a7SDavid Howells if (d_is_negative(old_dentry)) 48221da177e4SLinus Torvalds goto exit4; 4823f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 48241da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 48251da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 48261da177e4SLinus Torvalds goto exit4; 48270a7c3937SMiklos Szeredi error = -EEXIST; 48280a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 48290a7c3937SMiklos Szeredi goto exit5; 4830da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4831da1ce067SMiklos Szeredi error = -ENOENT; 4832da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4833da1ce067SMiklos Szeredi goto exit5; 4834da1ce067SMiklos Szeredi 4835da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4836da1ce067SMiklos Szeredi error = -ENOTDIR; 4837f5beed75SAl Viro if (new_last.name[new_last.len]) 4838da1ce067SMiklos Szeredi goto exit5; 4839da1ce067SMiklos Szeredi } 4840da1ce067SMiklos Szeredi } 48410a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 48420a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 48430a7c3937SMiklos Szeredi error = -ENOTDIR; 4844f5beed75SAl Viro if (old_last.name[old_last.len]) 48450a7c3937SMiklos Szeredi goto exit5; 4846f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 48470a7c3937SMiklos Szeredi goto exit5; 48480a7c3937SMiklos Szeredi } 48490a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 48500a7c3937SMiklos Szeredi error = -EINVAL; 48510a7c3937SMiklos Szeredi if (old_dentry == trap) 48520a7c3937SMiklos Szeredi goto exit5; 48531da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4854da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 48551da177e4SLinus Torvalds error = -ENOTEMPTY; 48561da177e4SLinus Torvalds if (new_dentry == trap) 48571da177e4SLinus Torvalds goto exit5; 48581da177e4SLinus Torvalds 4859f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4860f5beed75SAl Viro &new_path, new_dentry, flags); 4861be6d3e56SKentaro Takeda if (error) 4862c30dabfeSJan Kara goto exit5; 48639fe61450SChristian Brauner 48649fe61450SChristian Brauner rd.old_dir = old_path.dentry->d_inode; 48659fe61450SChristian Brauner rd.old_dentry = old_dentry; 48666521f891SChristian Brauner rd.old_mnt_userns = mnt_user_ns(old_path.mnt); 48679fe61450SChristian Brauner rd.new_dir = new_path.dentry->d_inode; 48689fe61450SChristian Brauner rd.new_dentry = new_dentry; 48696521f891SChristian Brauner rd.new_mnt_userns = mnt_user_ns(new_path.mnt); 48709fe61450SChristian Brauner rd.delegated_inode = &delegated_inode; 48719fe61450SChristian Brauner rd.flags = flags; 48729fe61450SChristian Brauner error = vfs_rename(&rd); 48731da177e4SLinus Torvalds exit5: 48741da177e4SLinus Torvalds dput(new_dentry); 48751da177e4SLinus Torvalds exit4: 48761da177e4SLinus Torvalds dput(old_dentry); 48771da177e4SLinus Torvalds exit3: 4878f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 48798e6d782cSJ. Bruce Fields if (delegated_inode) { 48808e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 48818e6d782cSJ. Bruce Fields if (!error) 48828e6d782cSJ. Bruce Fields goto retry_deleg; 48838e6d782cSJ. Bruce Fields } 4884f5beed75SAl Viro mnt_drop_write(old_path.mnt); 48851da177e4SLinus Torvalds exit2: 4886c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4887c6a94284SJeff Layton should_retry = true; 4888f5beed75SAl Viro path_put(&new_path); 48891da177e4SLinus Torvalds exit1: 4890f5beed75SAl Viro path_put(&old_path); 4891c6a94284SJeff Layton if (should_retry) { 4892c6a94284SJeff Layton should_retry = false; 4893c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4894c6a94284SJeff Layton goto retry; 4895c6a94284SJeff Layton } 48960ee50b47SDmitry Kadashev put_names: 4897e886663cSJens Axboe putname(from); 4898e886663cSJens Axboe putname(to); 48991da177e4SLinus Torvalds return error; 49001da177e4SLinus Torvalds } 49011da177e4SLinus Torvalds 4902ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4903ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4904ee81feb6SDominik Brodowski { 4905e886663cSJens Axboe return do_renameat2(olddfd, getname(oldname), newdfd, getname(newname), 4906e886663cSJens Axboe flags); 4907ee81feb6SDominik Brodowski } 4908ee81feb6SDominik Brodowski 4909520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4910520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4911520c8b16SMiklos Szeredi { 4912e886663cSJens Axboe return do_renameat2(olddfd, getname(oldname), newdfd, getname(newname), 4913e886663cSJens Axboe 0); 4914520c8b16SMiklos Szeredi } 4915520c8b16SMiklos Szeredi 4916a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 49175590ff0dSUlrich Drepper { 4918e886663cSJens Axboe return do_renameat2(AT_FDCWD, getname(oldname), AT_FDCWD, 4919e886663cSJens Axboe getname(newname), 0); 49205590ff0dSUlrich Drepper } 49215590ff0dSUlrich Drepper 49225d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 49231da177e4SLinus Torvalds { 49245d826c84SAl Viro int len = PTR_ERR(link); 49251da177e4SLinus Torvalds if (IS_ERR(link)) 49261da177e4SLinus Torvalds goto out; 49271da177e4SLinus Torvalds 49281da177e4SLinus Torvalds len = strlen(link); 49291da177e4SLinus Torvalds if (len > (unsigned) buflen) 49301da177e4SLinus Torvalds len = buflen; 49311da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 49321da177e4SLinus Torvalds len = -EFAULT; 49331da177e4SLinus Torvalds out: 49341da177e4SLinus Torvalds return len; 49351da177e4SLinus Torvalds } 49361da177e4SLinus Torvalds 4937d60874cdSMiklos Szeredi /** 4938fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4939fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4940fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4941fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4942fd4a0edfSMiklos Szeredi * 4943fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4944fd4a0edfSMiklos Szeredi * 4945fd4a0edfSMiklos Szeredi * Does not call security hook. 4946fd4a0edfSMiklos Szeredi */ 4947fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4948fd4a0edfSMiklos Szeredi { 4949fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4950f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4951f2df5da6SAl Viro const char *link; 4952f2df5da6SAl Viro int res; 4953fd4a0edfSMiklos Szeredi 495476fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 495576fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 495676fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 495776fca90eSMiklos Szeredi 495876fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4959fd4a0edfSMiklos Szeredi return -EINVAL; 4960fd4a0edfSMiklos Szeredi 496176fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 496276fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 496376fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 496476fca90eSMiklos Szeredi } 496576fca90eSMiklos Szeredi 49664c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4967f2df5da6SAl Viro if (!link) { 4968f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4969f2df5da6SAl Viro if (IS_ERR(link)) 4970f2df5da6SAl Viro return PTR_ERR(link); 4971f2df5da6SAl Viro } 4972f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4973f2df5da6SAl Viro do_delayed_call(&done); 4974f2df5da6SAl Viro return res; 4975fd4a0edfSMiklos Szeredi } 4976fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 49771da177e4SLinus Torvalds 4978d60874cdSMiklos Szeredi /** 4979d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4980d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4981d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4982d60874cdSMiklos Szeredi * 4983d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4984d60874cdSMiklos Szeredi * 4985d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4986d60874cdSMiklos Szeredi * 4987d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4988d60874cdSMiklos Szeredi */ 4989d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4990d60874cdSMiklos Szeredi { 4991d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4992d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4993d60874cdSMiklos Szeredi 4994d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4995d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4996d60874cdSMiklos Szeredi if (!res) 4997d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4998d60874cdSMiklos Szeredi } 4999d60874cdSMiklos Szeredi return res; 5000d60874cdSMiklos Szeredi } 5001d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 5002d60874cdSMiklos Szeredi 50031da177e4SLinus Torvalds /* get the link contents into pagecache */ 50046b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 5005fceef393SAl Viro struct delayed_call *callback) 50061da177e4SLinus Torvalds { 5007ebd09abbSDuane Griffin char *kaddr; 50081da177e4SLinus Torvalds struct page *page; 50096b255391SAl Viro struct address_space *mapping = inode->i_mapping; 50106b255391SAl Viro 5011d3883d4fSAl Viro if (!dentry) { 5012d3883d4fSAl Viro page = find_get_page(mapping, 0); 5013d3883d4fSAl Viro if (!page) 50146b255391SAl Viro return ERR_PTR(-ECHILD); 5015d3883d4fSAl Viro if (!PageUptodate(page)) { 5016d3883d4fSAl Viro put_page(page); 5017d3883d4fSAl Viro return ERR_PTR(-ECHILD); 5018d3883d4fSAl Viro } 5019d3883d4fSAl Viro } else { 5020090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 50211da177e4SLinus Torvalds if (IS_ERR(page)) 50226fe6900eSNick Piggin return (char*)page; 5023d3883d4fSAl Viro } 5024fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 502521fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 502621fc61c7SAl Viro kaddr = page_address(page); 50276b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 5028ebd09abbSDuane Griffin return kaddr; 50291da177e4SLinus Torvalds } 50301da177e4SLinus Torvalds 50316b255391SAl Viro EXPORT_SYMBOL(page_get_link); 50321da177e4SLinus Torvalds 5033fceef393SAl Viro void page_put_link(void *arg) 50341da177e4SLinus Torvalds { 5035fceef393SAl Viro put_page(arg); 50361da177e4SLinus Torvalds } 50374d359507SAl Viro EXPORT_SYMBOL(page_put_link); 50381da177e4SLinus Torvalds 5039aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 5040aa80deabSAl Viro { 5041fceef393SAl Viro DEFINE_DELAYED_CALL(done); 50426b255391SAl Viro int res = readlink_copy(buffer, buflen, 50436b255391SAl Viro page_get_link(dentry, d_inode(dentry), 5044fceef393SAl Viro &done)); 5045fceef393SAl Viro do_delayed_call(&done); 5046aa80deabSAl Viro return res; 5047aa80deabSAl Viro } 5048aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 5049aa80deabSAl Viro 505056f5746cSMatthew Wilcox (Oracle) int page_symlink(struct inode *inode, const char *symname, int len) 50511da177e4SLinus Torvalds { 50521da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 505327a77913SMatthew Wilcox (Oracle) const struct address_space_operations *aops = mapping->a_ops; 505456f5746cSMatthew Wilcox (Oracle) bool nofs = !mapping_gfp_constraint(mapping, __GFP_FS); 50550adb25d2SKirill Korotaev struct page *page; 5056afddba49SNick Piggin void *fsdata; 5057beb497abSDmitriy Monakhov int err; 50582d878178SMatthew Wilcox (Oracle) unsigned int flags; 50591da177e4SLinus Torvalds 50607e53cac4SNeilBrown retry: 50612d878178SMatthew Wilcox (Oracle) if (nofs) 50622d878178SMatthew Wilcox (Oracle) flags = memalloc_nofs_save(); 506327a77913SMatthew Wilcox (Oracle) err = aops->write_begin(NULL, mapping, 0, len-1, &page, &fsdata); 50642d878178SMatthew Wilcox (Oracle) if (nofs) 50652d878178SMatthew Wilcox (Oracle) memalloc_nofs_restore(flags); 50661da177e4SLinus Torvalds if (err) 5067afddba49SNick Piggin goto fail; 5068afddba49SNick Piggin 506921fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 5070afddba49SNick Piggin 507127a77913SMatthew Wilcox (Oracle) err = aops->write_end(NULL, mapping, 0, len-1, len-1, 5072afddba49SNick Piggin page, fsdata); 50731da177e4SLinus Torvalds if (err < 0) 50741da177e4SLinus Torvalds goto fail; 5075afddba49SNick Piggin if (err < len-1) 5076afddba49SNick Piggin goto retry; 5077afddba49SNick Piggin 50781da177e4SLinus Torvalds mark_inode_dirty(inode); 50791da177e4SLinus Torvalds return 0; 50801da177e4SLinus Torvalds fail: 50811da177e4SLinus Torvalds return err; 50821da177e4SLinus Torvalds } 50834d359507SAl Viro EXPORT_SYMBOL(page_symlink); 50840adb25d2SKirill Korotaev 508592e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 50866b255391SAl Viro .get_link = page_get_link, 50871da177e4SLinus Torvalds }; 50881da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 5089