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> 250eeca283SRobert Love #include <linux/fsnotify.h> 261da177e4SLinus Torvalds #include <linux/personality.h> 271da177e4SLinus Torvalds #include <linux/security.h> 286146f0d5SMimi Zohar #include <linux/ima.h> 291da177e4SLinus Torvalds #include <linux/syscalls.h> 301da177e4SLinus Torvalds #include <linux/mount.h> 311da177e4SLinus Torvalds #include <linux/audit.h> 3216f7e0feSRandy Dunlap #include <linux/capability.h> 33834f2a4aSTrond Myklebust #include <linux/file.h> 345590ff0dSUlrich Drepper #include <linux/fcntl.h> 3508ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 365ad4e53bSAl Viro #include <linux/fs_struct.h> 37e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3899d263d4SLinus Torvalds #include <linux/hash.h> 392a18da7aSGeorge Spelvin #include <linux/bitops.h> 40aeaa4a79SEric W. Biederman #include <linux/init_task.h> 417c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 421da177e4SLinus Torvalds 43e81e3f4dSEric Paris #include "internal.h" 44c7105365SAl Viro #include "mount.h" 45e81e3f4dSEric Paris 461da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 471da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 481da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 491da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 501da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 531da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 541da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 551da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 561da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 571da177e4SLinus Torvalds * the special cases of the former code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 601da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 611da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 641da177e4SLinus Torvalds * resolution to correspond with current state of the code. 651da177e4SLinus Torvalds * 661da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 671da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 681da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 691da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 701da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 711da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 721da177e4SLinus Torvalds */ 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 751da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 761da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 771da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 781da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 791da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8025985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 811da177e4SLinus Torvalds * 821da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 831da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 841da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 851da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 861da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 871da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 881da177e4SLinus Torvalds * and in the old Linux semantics. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 921da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 931da177e4SLinus Torvalds * 941da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 951da177e4SLinus Torvalds */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 981da177e4SLinus Torvalds * inside the path - always follow. 991da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1001da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1011da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1021da177e4SLinus Torvalds * otherwise - don't follow. 1031da177e4SLinus Torvalds * (applied in that order). 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1061da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1071da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1081da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1091da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 113a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1141da177e4SLinus Torvalds * any extra contention... 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1181da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1191da177e4SLinus Torvalds * kernel data space before using them.. 1201da177e4SLinus Torvalds * 1211da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1221da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1231da177e4SLinus Torvalds */ 1247950e385SJeff Layton 125fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12691a27b2aSJeff Layton 12751f39a1fSDavid Drysdale struct filename * 12891a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12991a27b2aSJeff Layton { 13094b5d262SAl Viro struct filename *result; 1317950e385SJeff Layton char *kname; 13294b5d262SAl Viro int len; 1331da177e4SLinus Torvalds 1347ac86265SJeff Layton result = audit_reusename(filename); 1357ac86265SJeff Layton if (result) 1367ac86265SJeff Layton return result; 1377ac86265SJeff Layton 1387950e385SJeff Layton result = __getname(); 1393f9f0aa6SLinus Torvalds if (unlikely(!result)) 1404043cde8SEric Paris return ERR_PTR(-ENOMEM); 1411da177e4SLinus Torvalds 1427950e385SJeff Layton /* 1437950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1447950e385SJeff Layton * allocation 1457950e385SJeff Layton */ 146fd2f7cb5SAl Viro kname = (char *)result->iname; 14791a27b2aSJeff Layton result->name = kname; 1487950e385SJeff Layton 14994b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15091a27b2aSJeff Layton if (unlikely(len < 0)) { 15194b5d262SAl Viro __putname(result); 15294b5d262SAl Viro return ERR_PTR(len); 15391a27b2aSJeff Layton } 1543f9f0aa6SLinus Torvalds 1557950e385SJeff Layton /* 1567950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1577950e385SJeff Layton * separate struct filename so we can dedicate the entire 1587950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1597950e385SJeff Layton * userland. 1607950e385SJeff Layton */ 16194b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 162fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1637950e385SJeff Layton kname = (char *)result; 1647950e385SJeff Layton 165fd2f7cb5SAl Viro /* 166fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 167fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 168fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 169fd2f7cb5SAl Viro */ 170fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17194b5d262SAl Viro if (unlikely(!result)) { 17294b5d262SAl Viro __putname(kname); 17394b5d262SAl Viro return ERR_PTR(-ENOMEM); 1747950e385SJeff Layton } 1757950e385SJeff Layton result->name = kname; 17694b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17794b5d262SAl Viro if (unlikely(len < 0)) { 17894b5d262SAl Viro __putname(kname); 17994b5d262SAl Viro kfree(result); 18094b5d262SAl Viro return ERR_PTR(len); 18194b5d262SAl Viro } 18294b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18394b5d262SAl Viro __putname(kname); 18494b5d262SAl Viro kfree(result); 18594b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18694b5d262SAl Viro } 1877950e385SJeff Layton } 1887950e385SJeff Layton 18994b5d262SAl Viro result->refcnt = 1; 1903f9f0aa6SLinus Torvalds /* The empty path is special. */ 1913f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1923f9f0aa6SLinus Torvalds if (empty) 1931fa1e7f6SAndy Whitcroft *empty = 1; 19494b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19594b5d262SAl Viro putname(result); 19694b5d262SAl Viro return ERR_PTR(-ENOENT); 1971da177e4SLinus Torvalds } 19894b5d262SAl Viro } 1997950e385SJeff Layton 2007950e385SJeff Layton result->uptr = filename; 201c4ad8f98SLinus Torvalds result->aname = NULL; 2021da177e4SLinus Torvalds audit_getname(result); 2031da177e4SLinus Torvalds return result; 2043f9f0aa6SLinus Torvalds } 2053f9f0aa6SLinus Torvalds 20691a27b2aSJeff Layton struct filename * 20791a27b2aSJeff Layton getname(const char __user * filename) 208f52e0c11SAl Viro { 209f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 210f52e0c11SAl Viro } 211f52e0c11SAl Viro 212c4ad8f98SLinus Torvalds struct filename * 213c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 214c4ad8f98SLinus Torvalds { 215c4ad8f98SLinus Torvalds struct filename *result; 21608518549SPaul Moore int len = strlen(filename) + 1; 217c4ad8f98SLinus Torvalds 218c4ad8f98SLinus Torvalds result = __getname(); 219c4ad8f98SLinus Torvalds if (unlikely(!result)) 220c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 221c4ad8f98SLinus Torvalds 22208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 223fd2f7cb5SAl Viro result->name = (char *)result->iname; 22408518549SPaul Moore } else if (len <= PATH_MAX) { 22530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 22608518549SPaul Moore struct filename *tmp; 22708518549SPaul Moore 22830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 22908518549SPaul Moore if (unlikely(!tmp)) { 23008518549SPaul Moore __putname(result); 23108518549SPaul Moore return ERR_PTR(-ENOMEM); 23208518549SPaul Moore } 23308518549SPaul Moore tmp->name = (char *)result; 23408518549SPaul Moore result = tmp; 23508518549SPaul Moore } else { 23608518549SPaul Moore __putname(result); 23708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23808518549SPaul Moore } 23908518549SPaul Moore memcpy((char *)result->name, filename, len); 240c4ad8f98SLinus Torvalds result->uptr = NULL; 241c4ad8f98SLinus Torvalds result->aname = NULL; 24255422d0bSPaul Moore result->refcnt = 1; 243fd3522fdSPaul Moore audit_getname(result); 244c4ad8f98SLinus Torvalds 245c4ad8f98SLinus Torvalds return result; 246c4ad8f98SLinus Torvalds } 247c4ad8f98SLinus Torvalds 24891a27b2aSJeff Layton void putname(struct filename *name) 2491da177e4SLinus Torvalds { 25055422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25155422d0bSPaul Moore 25255422d0bSPaul Moore if (--name->refcnt > 0) 25355422d0bSPaul Moore return; 25455422d0bSPaul Moore 255fd2f7cb5SAl Viro if (name->name != name->iname) { 25655422d0bSPaul Moore __putname(name->name); 25755422d0bSPaul Moore kfree(name); 25855422d0bSPaul Moore } else 25955422d0bSPaul Moore __putname(name); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262*47291baaSChristian Brauner /** 263*47291baaSChristian Brauner * check_acl - perform ACL permission checking 264*47291baaSChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 265*47291baaSChristian Brauner * @inode: inode to check permissions on 266*47291baaSChristian Brauner * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...) 267*47291baaSChristian Brauner * 268*47291baaSChristian Brauner * This function performs the ACL permission checking. Since this function 269*47291baaSChristian Brauner * retrieve POSIX acls it needs to know whether it is called from a blocking or 270*47291baaSChristian Brauner * non-blocking context and thus cares about the MAY_NOT_BLOCK bit. 271*47291baaSChristian Brauner * 272*47291baaSChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 273*47291baaSChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 274*47291baaSChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 275*47291baaSChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 276*47291baaSChristian Brauner * raw inode simply passs init_user_ns. 277*47291baaSChristian Brauner */ 278*47291baaSChristian Brauner static int check_acl(struct user_namespace *mnt_userns, 279*47291baaSChristian Brauner struct inode *inode, int mask) 280e77819e5SLinus Torvalds { 28184635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 282e77819e5SLinus Torvalds struct posix_acl *acl; 283e77819e5SLinus Torvalds 284e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2853567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2863567866bSAl Viro if (!acl) 287e77819e5SLinus Torvalds return -EAGAIN; 2883567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 289b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 290e77819e5SLinus Torvalds return -ECHILD; 291*47291baaSChristian Brauner return posix_acl_permission(mnt_userns, inode, acl, mask); 292e77819e5SLinus Torvalds } 293e77819e5SLinus Torvalds 2942982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2954e34e719SChristoph Hellwig if (IS_ERR(acl)) 2964e34e719SChristoph Hellwig return PTR_ERR(acl); 297e77819e5SLinus Torvalds if (acl) { 298*47291baaSChristian Brauner int error = posix_acl_permission(mnt_userns, inode, acl, mask); 299e77819e5SLinus Torvalds posix_acl_release(acl); 300e77819e5SLinus Torvalds return error; 301e77819e5SLinus Torvalds } 30284635d68SLinus Torvalds #endif 303e77819e5SLinus Torvalds 304e77819e5SLinus Torvalds return -EAGAIN; 305e77819e5SLinus Torvalds } 306e77819e5SLinus Torvalds 307*47291baaSChristian Brauner /** 308*47291baaSChristian Brauner * acl_permission_check - perform basic UNIX permission checking 309*47291baaSChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 310*47291baaSChristian Brauner * @inode: inode to check permissions on 311*47291baaSChristian Brauner * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...) 3125fc475b7SLinus Torvalds * 313*47291baaSChristian Brauner * This function performs the basic UNIX permission checking. Since this 314*47291baaSChristian Brauner * function may retrieve POSIX acls it needs to know whether it is called from a 315*47291baaSChristian Brauner * blocking or non-blocking context and thus cares about the MAY_NOT_BLOCK bit. 316*47291baaSChristian Brauner * 317*47291baaSChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 318*47291baaSChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 319*47291baaSChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 320*47291baaSChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 321*47291baaSChristian Brauner * raw inode simply passs init_user_ns. 3225909ccaaSLinus Torvalds */ 323*47291baaSChristian Brauner static int acl_permission_check(struct user_namespace *mnt_userns, 324*47291baaSChristian Brauner struct inode *inode, int mask) 3255909ccaaSLinus Torvalds { 32626cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 327*47291baaSChristian Brauner kuid_t i_uid; 3285909ccaaSLinus Torvalds 3295fc475b7SLinus Torvalds /* Are we the owner? If so, ACL's don't matter */ 330*47291baaSChristian Brauner i_uid = i_uid_into_mnt(mnt_userns, inode); 331*47291baaSChristian Brauner if (likely(uid_eq(current_fsuid(), i_uid))) { 3325fc475b7SLinus Torvalds mask &= 7; 3335909ccaaSLinus Torvalds mode >>= 6; 3345fc475b7SLinus Torvalds return (mask & ~mode) ? -EACCES : 0; 3355fc475b7SLinus Torvalds } 3365fc475b7SLinus Torvalds 3375fc475b7SLinus Torvalds /* Do we have ACL's? */ 338e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 339*47291baaSChristian Brauner int error = check_acl(mnt_userns, inode, mask); 3405909ccaaSLinus Torvalds if (error != -EAGAIN) 3415909ccaaSLinus Torvalds return error; 3425909ccaaSLinus Torvalds } 3435909ccaaSLinus Torvalds 3445fc475b7SLinus Torvalds /* Only RWX matters for group/other mode bits */ 3455fc475b7SLinus Torvalds mask &= 7; 3465fc475b7SLinus Torvalds 3475fc475b7SLinus Torvalds /* 3485fc475b7SLinus Torvalds * Are the group permissions different from 3495fc475b7SLinus Torvalds * the other permissions in the bits we care 3505fc475b7SLinus Torvalds * about? Need to check group ownership if so. 3515fc475b7SLinus Torvalds */ 3525fc475b7SLinus Torvalds if (mask & (mode ^ (mode >> 3))) { 353*47291baaSChristian Brauner kgid_t kgid = i_gid_into_mnt(mnt_userns, inode); 354*47291baaSChristian Brauner if (in_group_p(kgid)) 3555909ccaaSLinus Torvalds mode >>= 3; 3565909ccaaSLinus Torvalds } 3575909ccaaSLinus Torvalds 3585fc475b7SLinus Torvalds /* Bits in 'mode' clear that we require? */ 3595fc475b7SLinus Torvalds return (mask & ~mode) ? -EACCES : 0; 3605909ccaaSLinus Torvalds } 3611da177e4SLinus Torvalds 3621da177e4SLinus Torvalds /** 3631da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 364*47291baaSChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 3651da177e4SLinus Torvalds * @inode: inode to check access rights for 3665fc475b7SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, 3675fc475b7SLinus Torvalds * %MAY_NOT_BLOCK ...) 3681da177e4SLinus Torvalds * 3691da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3701da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3711da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 372b74c79e9SNick Piggin * are used for other things. 373b74c79e9SNick Piggin * 374b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 375b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 376b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 377*47291baaSChristian Brauner * 378*47291baaSChristian Brauner * If the inode has been found through an idmapped mount the user namespace of 379*47291baaSChristian Brauner * the vfsmount must be passed through @mnt_userns. This function will then take 380*47291baaSChristian Brauner * care to map the inode according to @mnt_userns before checking permissions. 381*47291baaSChristian Brauner * On non-idmapped mounts or if permission checking is to be performed on the 382*47291baaSChristian Brauner * raw inode simply passs init_user_ns. 3831da177e4SLinus Torvalds */ 384*47291baaSChristian Brauner int generic_permission(struct user_namespace *mnt_userns, struct inode *inode, 385*47291baaSChristian Brauner int mask) 3861da177e4SLinus Torvalds { 3875909ccaaSLinus Torvalds int ret; 3881da177e4SLinus Torvalds 3891da177e4SLinus Torvalds /* 390948409c7SAndreas Gruenbacher * Do the basic permission checks. 3911da177e4SLinus Torvalds */ 392*47291baaSChristian Brauner ret = acl_permission_check(mnt_userns, inode, mask); 3935909ccaaSLinus Torvalds if (ret != -EACCES) 3945909ccaaSLinus Torvalds return ret; 3951da177e4SLinus Torvalds 396d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 397d594e7ecSAl Viro /* DACs are overridable for directories */ 398d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 399*47291baaSChristian Brauner if (capable_wrt_inode_uidgid(mnt_userns, inode, 40023adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 401d594e7ecSAl Viro return 0; 402*47291baaSChristian Brauner if (capable_wrt_inode_uidgid(mnt_userns, inode, 4030558c1bfSChristian Brauner CAP_DAC_OVERRIDE)) 4041da177e4SLinus Torvalds return 0; 4052a4c2242SStephen Smalley return -EACCES; 4062a4c2242SStephen Smalley } 4071da177e4SLinus Torvalds 4081da177e4SLinus Torvalds /* 4091da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 4101da177e4SLinus Torvalds */ 4117ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 412d594e7ecSAl Viro if (mask == MAY_READ) 413*47291baaSChristian Brauner if (capable_wrt_inode_uidgid(mnt_userns, inode, 4140558c1bfSChristian Brauner CAP_DAC_READ_SEARCH)) 4151da177e4SLinus Torvalds return 0; 4162a4c2242SStephen Smalley /* 4172a4c2242SStephen Smalley * Read/write DACs are always overridable. 4182a4c2242SStephen Smalley * Executable DACs are overridable when there is 4192a4c2242SStephen Smalley * at least one exec bit set. 4202a4c2242SStephen Smalley */ 4212a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 422*47291baaSChristian Brauner if (capable_wrt_inode_uidgid(mnt_userns, inode, 4230558c1bfSChristian Brauner CAP_DAC_OVERRIDE)) 4242a4c2242SStephen Smalley return 0; 4251da177e4SLinus Torvalds 4261da177e4SLinus Torvalds return -EACCES; 4271da177e4SLinus Torvalds } 4284d359507SAl Viro EXPORT_SYMBOL(generic_permission); 4291da177e4SLinus Torvalds 430*47291baaSChristian Brauner /** 431*47291baaSChristian Brauner * do_inode_permission - UNIX permission checking 432*47291baaSChristian Brauner * @mnt_userns: user namespace of the mount the inode was found from 433*47291baaSChristian Brauner * @inode: inode to check permissions on 434*47291baaSChristian Brauner * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...) 435*47291baaSChristian Brauner * 4363ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 4373ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 4383ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 4393ddcd056SLinus Torvalds * permission function, use the fast case". 4403ddcd056SLinus Torvalds */ 441*47291baaSChristian Brauner static inline int do_inode_permission(struct user_namespace *mnt_userns, 442*47291baaSChristian Brauner struct inode *inode, int mask) 4433ddcd056SLinus Torvalds { 4443ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 4453ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 4463ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 4473ddcd056SLinus Torvalds 4483ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 4493ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 4503ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 4513ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 4523ddcd056SLinus Torvalds } 453*47291baaSChristian Brauner return generic_permission(mnt_userns, inode, mask); 4543ddcd056SLinus Torvalds } 4553ddcd056SLinus Torvalds 456cb23beb5SChristoph Hellwig /** 4570bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4580bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 45955852635SRandy Dunlap * @inode: Inode to check permission on 4600bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4610bdaea90SDavid Howells * 4620bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4630bdaea90SDavid Howells */ 4640bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4650bdaea90SDavid Howells { 4660bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4670bdaea90SDavid Howells umode_t mode = inode->i_mode; 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 470bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4710bdaea90SDavid Howells return -EROFS; 4720bdaea90SDavid Howells } 4730bdaea90SDavid Howells return 0; 4740bdaea90SDavid Howells } 4750bdaea90SDavid Howells 4760bdaea90SDavid Howells /** 4770bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 478*47291baaSChristian Brauner * @mnt_userns: User namespace of the mount the inode was found from 4790bdaea90SDavid Howells * @inode: Inode to check permission on 4800bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4810bdaea90SDavid Howells * 4820bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4830bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4840bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4850bdaea90SDavid Howells * 4860bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4870bdaea90SDavid Howells */ 488*47291baaSChristian Brauner int inode_permission(struct user_namespace *mnt_userns, 489*47291baaSChristian Brauner struct inode *inode, int mask) 4900bdaea90SDavid Howells { 4910bdaea90SDavid Howells int retval; 4920bdaea90SDavid Howells 4930bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4940bdaea90SDavid Howells if (retval) 4950bdaea90SDavid Howells return retval; 4964bfd054aSEric Biggers 4974bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4984bfd054aSEric Biggers /* 4994bfd054aSEric Biggers * Nobody gets write access to an immutable file. 5004bfd054aSEric Biggers */ 5014bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 5024bfd054aSEric Biggers return -EPERM; 5034bfd054aSEric Biggers 5044bfd054aSEric Biggers /* 5054bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 5064bfd054aSEric Biggers * written back improperly if their true value is unknown 5074bfd054aSEric Biggers * to the vfs. 5084bfd054aSEric Biggers */ 5094bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 5104bfd054aSEric Biggers return -EACCES; 5114bfd054aSEric Biggers } 5124bfd054aSEric Biggers 513*47291baaSChristian Brauner retval = do_inode_permission(mnt_userns, inode, mask); 5144bfd054aSEric Biggers if (retval) 5154bfd054aSEric Biggers return retval; 5164bfd054aSEric Biggers 5174bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 5184bfd054aSEric Biggers if (retval) 5194bfd054aSEric Biggers return retval; 5204bfd054aSEric Biggers 5214bfd054aSEric Biggers return security_inode_permission(inode, mask); 5220bdaea90SDavid Howells } 5234d359507SAl Viro EXPORT_SYMBOL(inode_permission); 5240bdaea90SDavid Howells 5250bdaea90SDavid Howells /** 5265dd784d0SJan Blunck * path_get - get a reference to a path 5275dd784d0SJan Blunck * @path: path to get the reference to 5285dd784d0SJan Blunck * 5295dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 5305dd784d0SJan Blunck */ 531dcf787f3SAl Viro void path_get(const struct path *path) 5325dd784d0SJan Blunck { 5335dd784d0SJan Blunck mntget(path->mnt); 5345dd784d0SJan Blunck dget(path->dentry); 5355dd784d0SJan Blunck } 5365dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 5375dd784d0SJan Blunck 5385dd784d0SJan Blunck /** 5391d957f9bSJan Blunck * path_put - put a reference to a path 5401d957f9bSJan Blunck * @path: path to put the reference to 5411d957f9bSJan Blunck * 5421d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 5431d957f9bSJan Blunck */ 544dcf787f3SAl Viro void path_put(const struct path *path) 5451da177e4SLinus Torvalds { 5461d957f9bSJan Blunck dput(path->dentry); 5471d957f9bSJan Blunck mntput(path->mnt); 5481da177e4SLinus Torvalds } 5491d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 5501da177e4SLinus Torvalds 551894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 5521f55a6ecSAl Viro struct nameidata { 5531f55a6ecSAl Viro struct path path; 5541f55a6ecSAl Viro struct qstr last; 5551f55a6ecSAl Viro struct path root; 5561f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5571f55a6ecSAl Viro unsigned int flags; 558ab87f9a5SAleksa Sarai unsigned seq, m_seq, r_seq; 5591f55a6ecSAl Viro int last_type; 5601f55a6ecSAl Viro unsigned depth; 561756daf26SNeilBrown int total_link_count; 562697fc6caSAl Viro struct saved { 563697fc6caSAl Viro struct path link; 564fceef393SAl Viro struct delayed_call done; 565697fc6caSAl Viro const char *name; 5660450b2d1SAl Viro unsigned seq; 567894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5689883d185SAl Viro struct filename *name; 5699883d185SAl Viro struct nameidata *saved; 5709883d185SAl Viro unsigned root_seq; 5719883d185SAl Viro int dfd; 5720f705953SAl Viro kuid_t dir_uid; 5730f705953SAl Viro umode_t dir_mode; 5743859a271SKees Cook } __randomize_layout; 5751f55a6ecSAl Viro 5769883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 577894bc8c4SAl Viro { 578756daf26SNeilBrown struct nameidata *old = current->nameidata; 579756daf26SNeilBrown p->stack = p->internal; 580c8a53ee5SAl Viro p->dfd = dfd; 581c8a53ee5SAl Viro p->name = name; 582756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5839883d185SAl Viro p->saved = old; 584756daf26SNeilBrown current->nameidata = p; 585894bc8c4SAl Viro } 586894bc8c4SAl Viro 5879883d185SAl Viro static void restore_nameidata(void) 588894bc8c4SAl Viro { 5899883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 590756daf26SNeilBrown 591756daf26SNeilBrown current->nameidata = old; 592756daf26SNeilBrown if (old) 593756daf26SNeilBrown old->total_link_count = now->total_link_count; 594e1a63bbcSAl Viro if (now->stack != now->internal) 595756daf26SNeilBrown kfree(now->stack); 596894bc8c4SAl Viro } 597894bc8c4SAl Viro 59860ef60c7SAl Viro static bool nd_alloc_stack(struct nameidata *nd) 599894bc8c4SAl Viro { 600bc40aee0SAl Viro struct saved *p; 601bc40aee0SAl Viro 6026da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 60360ef60c7SAl Viro nd->flags & LOOKUP_RCU ? GFP_ATOMIC : GFP_KERNEL); 604bc40aee0SAl Viro if (unlikely(!p)) 60560ef60c7SAl Viro return false; 606894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 607894bc8c4SAl Viro nd->stack = p; 60860ef60c7SAl Viro return true; 609894bc8c4SAl Viro } 610894bc8c4SAl Viro 611397d425dSEric W. Biederman /** 6126b03f7edSAl Viro * path_connected - Verify that a dentry is below mnt.mnt_root 613397d425dSEric W. Biederman * 614397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 615397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 616397d425dSEric W. Biederman */ 6176b03f7edSAl Viro static bool path_connected(struct vfsmount *mnt, struct dentry *dentry) 618397d425dSEric W. Biederman { 61995dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 620397d425dSEric W. Biederman 621402dd2cfSChristoph Hellwig /* Bind mounts can have disconnected paths */ 622402dd2cfSChristoph Hellwig if (mnt->mnt_root == sb->s_root) 623397d425dSEric W. Biederman return true; 624397d425dSEric W. Biederman 6256b03f7edSAl Viro return is_subdir(dentry, mnt->mnt_root); 626397d425dSEric W. Biederman } 627397d425dSEric W. Biederman 6287973387aSAl Viro static void drop_links(struct nameidata *nd) 6297973387aSAl Viro { 6307973387aSAl Viro int i = nd->depth; 6317973387aSAl Viro while (i--) { 6327973387aSAl Viro struct saved *last = nd->stack + i; 633fceef393SAl Viro do_delayed_call(&last->done); 634fceef393SAl Viro clear_delayed_call(&last->done); 6357973387aSAl Viro } 6367973387aSAl Viro } 6377973387aSAl Viro 6387973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6397973387aSAl Viro { 6407973387aSAl Viro drop_links(nd); 6417973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6427973387aSAl Viro int i; 6437973387aSAl Viro path_put(&nd->path); 6447973387aSAl Viro for (i = 0; i < nd->depth; i++) 6457973387aSAl Viro path_put(&nd->stack[i].link); 64684a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 647102b8af2SAl Viro path_put(&nd->root); 64884a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 649102b8af2SAl Viro } 6507973387aSAl Viro } else { 6517973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6527973387aSAl Viro rcu_read_unlock(); 6537973387aSAl Viro } 6547973387aSAl Viro nd->depth = 0; 6557973387aSAl Viro } 6567973387aSAl Viro 6577973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6582aa38470SAl Viro static bool __legitimize_path(struct path *path, unsigned seq, unsigned mseq) 6597973387aSAl Viro { 6602aa38470SAl Viro int res = __legitimize_mnt(path->mnt, mseq); 6617973387aSAl Viro if (unlikely(res)) { 6627973387aSAl Viro if (res > 0) 6637973387aSAl Viro path->mnt = NULL; 6647973387aSAl Viro path->dentry = NULL; 6657973387aSAl Viro return false; 6667973387aSAl Viro } 6677973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6687973387aSAl Viro path->dentry = NULL; 6697973387aSAl Viro return false; 6707973387aSAl Viro } 6717973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6727973387aSAl Viro } 6737973387aSAl Viro 6742aa38470SAl Viro static inline bool legitimize_path(struct nameidata *nd, 6752aa38470SAl Viro struct path *path, unsigned seq) 6762aa38470SAl Viro { 6775bd73286SAl Viro return __legitimize_path(path, seq, nd->m_seq); 6782aa38470SAl Viro } 6792aa38470SAl Viro 6807973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6817973387aSAl Viro { 6827973387aSAl Viro int i; 6837973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6847973387aSAl Viro struct saved *last = nd->stack + i; 6857973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6867973387aSAl Viro drop_links(nd); 6877973387aSAl Viro nd->depth = i + 1; 6887973387aSAl Viro return false; 6897973387aSAl Viro } 6907973387aSAl Viro } 6917973387aSAl Viro return true; 6927973387aSAl Viro } 6937973387aSAl Viro 694ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 695ee594bffSAl Viro { 696adb21d2bSAleksa Sarai /* 697adb21d2bSAleksa Sarai * For scoped-lookups (where nd->root has been zeroed), we need to 698adb21d2bSAleksa Sarai * restart the whole lookup from scratch -- because set_root() is wrong 699adb21d2bSAleksa Sarai * for these lookups (nd->dfd is the root, not the filesystem root). 700adb21d2bSAleksa Sarai */ 701adb21d2bSAleksa Sarai if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) 702adb21d2bSAleksa Sarai return false; 703adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 704ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 705ee594bffSAl Viro return true; 70684a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 707ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 708ee594bffSAl Viro } 709ee594bffSAl Viro 71019660af7SAl Viro /* 71131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 71219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 71319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 71457e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 71519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 71619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 71719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 71819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 71931e6b01fSNick Piggin */ 72031e6b01fSNick Piggin 72131e6b01fSNick Piggin /** 72219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 72319660af7SAl Viro * @nd: nameidata pathwalk data 72439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 72531e6b01fSNick Piggin * 7264675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 7274675ac39SAl Viro * for ref-walk mode. 7284675ac39SAl Viro * Must be called from rcu-walk context. 7297973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 7307973387aSAl Viro * terminate_walk(). 73131e6b01fSNick Piggin */ 7324675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 73331e6b01fSNick Piggin { 73431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 73531e6b01fSNick Piggin 73631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 737e5c832d5SLinus Torvalds 738e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 7397973387aSAl Viro if (unlikely(!legitimize_links(nd))) 7404675ac39SAl Viro goto out1; 74184a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 74284a2bd39SAl Viro goto out; 743ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 7444675ac39SAl Viro goto out; 7454675ac39SAl Viro rcu_read_unlock(); 7464675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 7474675ac39SAl Viro return 0; 7484675ac39SAl Viro 74984a2bd39SAl Viro out1: 7504675ac39SAl Viro nd->path.mnt = NULL; 7514675ac39SAl Viro nd->path.dentry = NULL; 7524675ac39SAl Viro out: 7534675ac39SAl Viro rcu_read_unlock(); 7544675ac39SAl Viro return -ECHILD; 7554675ac39SAl Viro } 7564675ac39SAl Viro 7574675ac39SAl Viro /** 7584675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 7594675ac39SAl Viro * @nd: nameidata pathwalk data 7604675ac39SAl Viro * @dentry: child of nd->path.dentry 7614675ac39SAl Viro * @seq: seq number to check dentry against 7624675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7634675ac39SAl Viro * 7644675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7654675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7664675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7674675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7684675ac39SAl Viro * terminate_walk(). 7694675ac39SAl Viro */ 7704675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7714675ac39SAl Viro { 7724675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7734675ac39SAl Viro 7744675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7754675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7764675ac39SAl Viro goto out2; 7777973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7787973387aSAl Viro goto out2; 7794675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7807973387aSAl Viro goto out1; 78148a066e7SAl Viro 78215570086SLinus Torvalds /* 7834675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7844675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7854675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7864675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7874675ac39SAl Viro * know the parent must still be valid if the child sequence number is 78815570086SLinus Torvalds */ 7894675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 790e5c832d5SLinus Torvalds goto out; 79184a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 79284a2bd39SAl Viro goto out_dput; 793e5c832d5SLinus Torvalds /* 794e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 795e5c832d5SLinus Torvalds * still valid and get it if required. 796e5c832d5SLinus Torvalds */ 79784a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 79884a2bd39SAl Viro goto out_dput; 7998b61e74fSAl Viro rcu_read_unlock(); 80031e6b01fSNick Piggin return 0; 80119660af7SAl Viro 8027973387aSAl Viro out2: 8037973387aSAl Viro nd->path.mnt = NULL; 8047973387aSAl Viro out1: 8057973387aSAl Viro nd->path.dentry = NULL; 806e5c832d5SLinus Torvalds out: 8078b61e74fSAl Viro rcu_read_unlock(); 80884a2bd39SAl Viro return -ECHILD; 80984a2bd39SAl Viro out_dput: 81084a2bd39SAl Viro rcu_read_unlock(); 81184a2bd39SAl Viro dput(dentry); 81231e6b01fSNick Piggin return -ECHILD; 81331e6b01fSNick Piggin } 81431e6b01fSNick Piggin 8154ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 81634286d66SNick Piggin { 817a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 8184ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 819a89f8337SAl Viro else 820a89f8337SAl Viro return 1; 82134286d66SNick Piggin } 82234286d66SNick Piggin 8239f1fafeeSAl Viro /** 8249f1fafeeSAl Viro * complete_walk - successful completion of path walk 8259f1fafeeSAl Viro * @nd: pointer nameidata 82639159de2SJeff Layton * 8279f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 8289f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 8299f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 8309f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 8319f1fafeeSAl Viro * need to drop nd->path. 83239159de2SJeff Layton */ 8339f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 83439159de2SJeff Layton { 83516c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 83639159de2SJeff Layton int status; 83739159de2SJeff Layton 8389f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 839adb21d2bSAleksa Sarai /* 840adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 841adb21d2bSAleksa Sarai * externally-managed nd->root. 842adb21d2bSAleksa Sarai */ 843adb21d2bSAleksa Sarai if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) 8449f1fafeeSAl Viro nd->root.mnt = NULL; 8454675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 84648a066e7SAl Viro return -ECHILD; 84748a066e7SAl Viro } 8489f1fafeeSAl Viro 849adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 850adb21d2bSAleksa Sarai /* 851adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 852adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 853adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 854adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 855adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 856adb21d2bSAleksa Sarai * 857adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 858adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 859adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 860adb21d2bSAleksa Sarai * requested root to userspace. 861adb21d2bSAleksa Sarai * 862adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 863adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 864adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 865adb21d2bSAleksa Sarai */ 866adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 867adb21d2bSAleksa Sarai return -EXDEV; 868adb21d2bSAleksa Sarai } 869adb21d2bSAleksa Sarai 87016c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 87139159de2SJeff Layton return 0; 87239159de2SJeff Layton 873ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 87416c2cd71SAl Viro return 0; 87516c2cd71SAl Viro 876ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 87739159de2SJeff Layton if (status > 0) 87839159de2SJeff Layton return 0; 87939159de2SJeff Layton 88016c2cd71SAl Viro if (!status) 88139159de2SJeff Layton status = -ESTALE; 88216c2cd71SAl Viro 88339159de2SJeff Layton return status; 88439159de2SJeff Layton } 88539159de2SJeff Layton 886740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 8872a737871SAl Viro { 88831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8899e6697e2SAl Viro 890adb21d2bSAleksa Sarai /* 891adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 892adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 893adb21d2bSAleksa Sarai * from the dirfd. 894adb21d2bSAleksa Sarai */ 895adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 896adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 897adb21d2bSAleksa Sarai 8989e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8998f47a016SAl Viro unsigned seq; 900c28cc364SNick Piggin 901c28cc364SNick Piggin do { 902c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 90331e6b01fSNick Piggin nd->root = fs->root; 9048f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 905c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 9069e6697e2SAl Viro } else { 9079e6697e2SAl Viro get_fs_root(fs, &nd->root); 90884a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 9099e6697e2SAl Viro } 910740a1678SAleksa Sarai return 0; 91131e6b01fSNick Piggin } 91231e6b01fSNick Piggin 913248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 914248fb5b9SAl Viro { 915adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 916adb21d2bSAleksa Sarai return -EXDEV; 91772ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 91872ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 91972ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 92072ba2929SAleksa Sarai return -EXDEV; 92172ba2929SAleksa Sarai } 922740a1678SAleksa Sarai if (!nd->root.mnt) { 923740a1678SAleksa Sarai int error = set_root(nd); 924740a1678SAleksa Sarai if (error) 925740a1678SAleksa Sarai return error; 926740a1678SAleksa Sarai } 927248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 928248fb5b9SAl Viro struct dentry *d; 929248fb5b9SAl Viro nd->path = nd->root; 930248fb5b9SAl Viro d = nd->path.dentry; 931248fb5b9SAl Viro nd->inode = d->d_inode; 932248fb5b9SAl Viro nd->seq = nd->root_seq; 933248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 934248fb5b9SAl Viro return -ECHILD; 935248fb5b9SAl Viro } else { 936248fb5b9SAl Viro path_put(&nd->path); 937248fb5b9SAl Viro nd->path = nd->root; 938248fb5b9SAl Viro path_get(&nd->path); 939248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 940248fb5b9SAl Viro } 941248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 942248fb5b9SAl Viro return 0; 943248fb5b9SAl Viro } 944248fb5b9SAl Viro 945b5fb63c1SChristoph Hellwig /* 9466b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 947b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 948b5fb63c1SChristoph Hellwig */ 9491bc82070SAleksa Sarai int nd_jump_link(struct path *path) 950b5fb63c1SChristoph Hellwig { 9514b99d499SAleksa Sarai int error = -ELOOP; 9526e77137bSAl Viro struct nameidata *nd = current->nameidata; 953b5fb63c1SChristoph Hellwig 9544b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 9554b99d499SAleksa Sarai goto err; 9564b99d499SAleksa Sarai 95772ba2929SAleksa Sarai error = -EXDEV; 95872ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 95972ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 96072ba2929SAleksa Sarai goto err; 96172ba2929SAleksa Sarai } 962adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 963adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 964adb21d2bSAleksa Sarai goto err; 96572ba2929SAleksa Sarai 9664b99d499SAleksa Sarai path_put(&nd->path); 967b5fb63c1SChristoph Hellwig nd->path = *path; 968b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 969b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 9701bc82070SAleksa Sarai return 0; 9714b99d499SAleksa Sarai 9724b99d499SAleksa Sarai err: 9734b99d499SAleksa Sarai path_put(path); 9744b99d499SAleksa Sarai return error; 975b5fb63c1SChristoph Hellwig } 976b5fb63c1SChristoph Hellwig 977b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 978574197e0SAl Viro { 97921c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 980fceef393SAl Viro do_delayed_call(&last->done); 9816548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 982b9ff4429SAl Viro path_put(&last->link); 983574197e0SAl Viro } 984574197e0SAl Viro 985561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 986561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 98730aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 98830aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 989800179c9SKees Cook 990800179c9SKees Cook /** 991800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 99255852635SRandy Dunlap * @nd: nameidata pathwalk data 993800179c9SKees Cook * 994800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 995800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 996800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 997800179c9SKees Cook * processes from failing races against path names that may change out 998800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 999800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 1000800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 1001800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 1002800179c9SKees Cook * 1003800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 1004800179c9SKees Cook */ 1005ad6cc4c3SAl Viro static inline int may_follow_link(struct nameidata *nd, const struct inode *inode) 1006800179c9SKees Cook { 1007800179c9SKees Cook if (!sysctl_protected_symlinks) 1008800179c9SKees Cook return 0; 1009800179c9SKees Cook 1010800179c9SKees Cook /* Allowed if owner and follower match. */ 101181abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 1012800179c9SKees Cook return 0; 1013800179c9SKees Cook 1014800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 10150f705953SAl Viro if ((nd->dir_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 1016800179c9SKees Cook return 0; 1017800179c9SKees Cook 1018800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 10190f705953SAl Viro if (uid_valid(nd->dir_uid) && uid_eq(nd->dir_uid, inode->i_uid)) 1020800179c9SKees Cook return 0; 1021800179c9SKees Cook 102231956502SAl Viro if (nd->flags & LOOKUP_RCU) 102331956502SAl Viro return -ECHILD; 102431956502SAl Viro 1025ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 1026245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 1027800179c9SKees Cook return -EACCES; 1028800179c9SKees Cook } 1029800179c9SKees Cook 1030800179c9SKees Cook /** 1031800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 1032800179c9SKees Cook * @inode: the source inode to hardlink from 1033800179c9SKees Cook * 1034800179c9SKees Cook * Return false if at least one of the following conditions: 1035800179c9SKees Cook * - inode is not a regular file 1036800179c9SKees Cook * - inode is setuid 1037800179c9SKees Cook * - inode is setgid and group-exec 1038800179c9SKees Cook * - access failure for read and write 1039800179c9SKees Cook * 1040800179c9SKees Cook * Otherwise returns true. 1041800179c9SKees Cook */ 1042800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 1043800179c9SKees Cook { 1044800179c9SKees Cook umode_t mode = inode->i_mode; 1045800179c9SKees Cook 1046800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1047800179c9SKees Cook if (!S_ISREG(mode)) 1048800179c9SKees Cook return false; 1049800179c9SKees Cook 1050800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1051800179c9SKees Cook if (mode & S_ISUID) 1052800179c9SKees Cook return false; 1053800179c9SKees Cook 1054800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1055800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1056800179c9SKees Cook return false; 1057800179c9SKees Cook 1058800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 1059*47291baaSChristian Brauner if (inode_permission(&init_user_ns, inode, MAY_READ | MAY_WRITE)) 1060800179c9SKees Cook return false; 1061800179c9SKees Cook 1062800179c9SKees Cook return true; 1063800179c9SKees Cook } 1064800179c9SKees Cook 1065800179c9SKees Cook /** 1066800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 1067800179c9SKees Cook * @link: the source to hardlink from 1068800179c9SKees Cook * 1069800179c9SKees Cook * Block hardlink when all of: 1070800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1071800179c9SKees Cook * - fsuid does not match inode 1072800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1073f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1074800179c9SKees Cook * 1075800179c9SKees Cook * Returns 0 if successful, -ve on error. 1076800179c9SKees Cook */ 1077812931d6SChristoph Hellwig int may_linkat(struct path *link) 1078800179c9SKees Cook { 1079593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1080593d1ce8SEric W. Biederman 1081593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1082593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 1083593d1ce8SEric W. Biederman return -EOVERFLOW; 1084800179c9SKees Cook 1085800179c9SKees Cook if (!sysctl_protected_hardlinks) 1086800179c9SKees Cook return 0; 1087800179c9SKees Cook 1088800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1089800179c9SKees Cook * otherwise, it must be a safe source. 1090800179c9SKees Cook */ 1091cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 1092800179c9SKees Cook return 0; 1093800179c9SKees Cook 1094245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1095800179c9SKees Cook return -EPERM; 1096800179c9SKees Cook } 1097800179c9SKees Cook 109830aba665SSalvatore Mesoraca /** 109930aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 110030aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 110130aba665SSalvatore Mesoraca * exist. 1102d0cb5018SAl Viro * @dir_mode: mode bits of directory 1103d0cb5018SAl Viro * @dir_uid: owner of directory 110430aba665SSalvatore Mesoraca * @inode: the inode of the file to open 110530aba665SSalvatore Mesoraca * 110630aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 110730aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 110830aba665SSalvatore Mesoraca * - the file already exists 110930aba665SSalvatore Mesoraca * - we are in a sticky directory 111030aba665SSalvatore Mesoraca * - we don't own the file 111130aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 111230aba665SSalvatore Mesoraca * - the directory is world writable 111330aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 111430aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 111530aba665SSalvatore Mesoraca * be enough. 111630aba665SSalvatore Mesoraca * 111730aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 111830aba665SSalvatore Mesoraca */ 1119d0cb5018SAl Viro static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid, 112030aba665SSalvatore Mesoraca struct inode * const inode) 112130aba665SSalvatore Mesoraca { 112230aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 112330aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1124d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1125d0cb5018SAl Viro uid_eq(inode->i_uid, dir_uid) || 112630aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 112730aba665SSalvatore Mesoraca return 0; 112830aba665SSalvatore Mesoraca 1129d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1130d0cb5018SAl Viro (dir_mode & 0020 && 113130aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 113230aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1133245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1134245d7369SKees Cook "sticky_create_fifo" : 1135245d7369SKees Cook "sticky_create_regular"; 1136245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 113730aba665SSalvatore Mesoraca return -EACCES; 113830aba665SSalvatore Mesoraca } 113930aba665SSalvatore Mesoraca return 0; 114030aba665SSalvatore Mesoraca } 114130aba665SSalvatore Mesoraca 1142f015f126SDavid Howells /* 1143f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1144f015f126SDavid Howells * 1145f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1146f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1147f015f126SDavid Howells * Up is towards /. 1148f015f126SDavid Howells * 1149f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1150f015f126SDavid Howells * root. 1151f015f126SDavid Howells */ 1152bab77ebfSAl Viro int follow_up(struct path *path) 11531da177e4SLinus Torvalds { 11540714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11550714a533SAl Viro struct mount *parent; 11561da177e4SLinus Torvalds struct dentry *mountpoint; 115799b7db7bSNick Piggin 115848a066e7SAl Viro read_seqlock_excl(&mount_lock); 11590714a533SAl Viro parent = mnt->mnt_parent; 11603c0a6163SAl Viro if (parent == mnt) { 116148a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11621da177e4SLinus Torvalds return 0; 11631da177e4SLinus Torvalds } 11640714a533SAl Viro mntget(&parent->mnt); 1165a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 116648a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1167bab77ebfSAl Viro dput(path->dentry); 1168bab77ebfSAl Viro path->dentry = mountpoint; 1169bab77ebfSAl Viro mntput(path->mnt); 11700714a533SAl Viro path->mnt = &parent->mnt; 11711da177e4SLinus Torvalds return 1; 11721da177e4SLinus Torvalds } 11734d359507SAl Viro EXPORT_SYMBOL(follow_up); 11741da177e4SLinus Torvalds 11757ef482faSAl Viro static bool choose_mountpoint_rcu(struct mount *m, const struct path *root, 11767ef482faSAl Viro struct path *path, unsigned *seqp) 11777ef482faSAl Viro { 11787ef482faSAl Viro while (mnt_has_parent(m)) { 11797ef482faSAl Viro struct dentry *mountpoint = m->mnt_mountpoint; 11807ef482faSAl Viro 11817ef482faSAl Viro m = m->mnt_parent; 11827ef482faSAl Viro if (unlikely(root->dentry == mountpoint && 11837ef482faSAl Viro root->mnt == &m->mnt)) 11847ef482faSAl Viro break; 11857ef482faSAl Viro if (mountpoint != m->mnt.mnt_root) { 11867ef482faSAl Viro path->mnt = &m->mnt; 11877ef482faSAl Viro path->dentry = mountpoint; 11887ef482faSAl Viro *seqp = read_seqcount_begin(&mountpoint->d_seq); 11897ef482faSAl Viro return true; 11907ef482faSAl Viro } 11917ef482faSAl Viro } 11927ef482faSAl Viro return false; 11937ef482faSAl Viro } 11947ef482faSAl Viro 11952aa38470SAl Viro static bool choose_mountpoint(struct mount *m, const struct path *root, 11962aa38470SAl Viro struct path *path) 11972aa38470SAl Viro { 11982aa38470SAl Viro bool found; 11992aa38470SAl Viro 12002aa38470SAl Viro rcu_read_lock(); 12012aa38470SAl Viro while (1) { 12022aa38470SAl Viro unsigned seq, mseq = read_seqbegin(&mount_lock); 12032aa38470SAl Viro 12042aa38470SAl Viro found = choose_mountpoint_rcu(m, root, path, &seq); 12052aa38470SAl Viro if (unlikely(!found)) { 12062aa38470SAl Viro if (!read_seqretry(&mount_lock, mseq)) 12072aa38470SAl Viro break; 12082aa38470SAl Viro } else { 12092aa38470SAl Viro if (likely(__legitimize_path(path, seq, mseq))) 12102aa38470SAl Viro break; 12112aa38470SAl Viro rcu_read_unlock(); 12122aa38470SAl Viro path_put(path); 12132aa38470SAl Viro rcu_read_lock(); 12142aa38470SAl Viro } 12152aa38470SAl Viro } 12162aa38470SAl Viro rcu_read_unlock(); 12172aa38470SAl Viro return found; 12182aa38470SAl Viro } 12192aa38470SAl Viro 1220b5c84bf6SNick Piggin /* 12219875cf80SDavid Howells * Perform an automount 12229875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 12239875cf80SDavid Howells * were called with. 12241da177e4SLinus Torvalds */ 12251c9f5e06SAl Viro static int follow_automount(struct path *path, int *count, unsigned lookup_flags) 122631e6b01fSNick Piggin { 122725e195aaSAl Viro struct dentry *dentry = path->dentry; 12289875cf80SDavid Howells 12290ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 12300ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 12310ec26fd0SMiklos Szeredi * the name. 12320ec26fd0SMiklos Szeredi * 12330ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 12345a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 12350ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 12360ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 12370ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 12380ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 12395a30d8a2SDavid Howells */ 12401c9f5e06SAl Viro if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 12415d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 124225e195aaSAl Viro dentry->d_inode) 12439875cf80SDavid Howells return -EISDIR; 12440ec26fd0SMiklos Szeredi 12451c9f5e06SAl Viro if (count && (*count)++ >= MAXSYMLINKS) 12469875cf80SDavid Howells return -ELOOP; 12479875cf80SDavid Howells 124825e195aaSAl Viro return finish_automount(dentry->d_op->d_automount(path), path); 1249ea5b778aSDavid Howells } 12509875cf80SDavid Howells 12519875cf80SDavid Howells /* 12529deed3ebSAl Viro * mount traversal - out-of-line part. One note on ->d_flags accesses - 12539deed3ebSAl Viro * dentries are pinned but not locked here, so negative dentry can go 12549deed3ebSAl Viro * positive right under us. Use of smp_load_acquire() provides a barrier 12559deed3ebSAl Viro * sufficient for ->d_inode and ->d_flags consistency. 12569875cf80SDavid Howells */ 12579deed3ebSAl Viro static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped, 12589deed3ebSAl Viro int *count, unsigned lookup_flags) 12599875cf80SDavid Howells { 12609deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 12619875cf80SDavid Howells bool need_mntput = false; 12628aef1884SAl Viro int ret = 0; 12639875cf80SDavid Howells 12649deed3ebSAl Viro while (flags & DCACHE_MANAGED_DENTRY) { 1265cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1266cc53ce53SDavid Howells * being held. */ 1267d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1268fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1269508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1270cc53ce53SDavid Howells if (ret < 0) 12718aef1884SAl Viro break; 1272cc53ce53SDavid Howells } 1273cc53ce53SDavid Howells 12749deed3ebSAl Viro if (flags & DCACHE_MOUNTED) { // something's mounted on it.. 12759875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12769deed3ebSAl Viro if (mounted) { // ... in our namespace 12779875cf80SDavid Howells dput(path->dentry); 12789875cf80SDavid Howells if (need_mntput) 1279463ffb2eSAl Viro mntput(path->mnt); 1280463ffb2eSAl Viro path->mnt = mounted; 1281463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12829deed3ebSAl Viro // here we know it's positive 12839deed3ebSAl Viro flags = path->dentry->d_flags; 12849875cf80SDavid Howells need_mntput = true; 12859875cf80SDavid Howells continue; 1286463ffb2eSAl Viro } 12871da177e4SLinus Torvalds } 12889875cf80SDavid Howells 12899deed3ebSAl Viro if (!(flags & DCACHE_NEED_AUTOMOUNT)) 12909deed3ebSAl Viro break; 12919deed3ebSAl Viro 12929deed3ebSAl Viro // uncovered automount point 12939deed3ebSAl Viro ret = follow_automount(path, count, lookup_flags); 12949deed3ebSAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 12959875cf80SDavid Howells if (ret < 0) 12968aef1884SAl Viro break; 12979875cf80SDavid Howells } 12989875cf80SDavid Howells 12999deed3ebSAl Viro if (ret == -EISDIR) 13009deed3ebSAl Viro ret = 0; 13019deed3ebSAl Viro // possible if you race with several mount --move 13029deed3ebSAl Viro if (need_mntput && path->mnt == mnt) 13038aef1884SAl Viro mntput(path->mnt); 13049deed3ebSAl Viro if (!ret && unlikely(d_flags_negative(flags))) 1305d41efb52SAl Viro ret = -ENOENT; 13069deed3ebSAl Viro *jumped = need_mntput; 13078402752eSAl Viro return ret; 13081da177e4SLinus Torvalds } 13091da177e4SLinus Torvalds 13109deed3ebSAl Viro static inline int traverse_mounts(struct path *path, bool *jumped, 13119deed3ebSAl Viro int *count, unsigned lookup_flags) 13129deed3ebSAl Viro { 13139deed3ebSAl Viro unsigned flags = smp_load_acquire(&path->dentry->d_flags); 13149deed3ebSAl Viro 13159deed3ebSAl Viro /* fastpath */ 13169deed3ebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) { 13179deed3ebSAl Viro *jumped = false; 13189deed3ebSAl Viro if (unlikely(d_flags_negative(flags))) 13199deed3ebSAl Viro return -ENOENT; 13209deed3ebSAl Viro return 0; 13219deed3ebSAl Viro } 13229deed3ebSAl Viro return __traverse_mounts(path, flags, jumped, count, lookup_flags); 13239deed3ebSAl Viro } 13249deed3ebSAl Viro 1325cc53ce53SDavid Howells int follow_down_one(struct path *path) 13261da177e4SLinus Torvalds { 13271da177e4SLinus Torvalds struct vfsmount *mounted; 13281da177e4SLinus Torvalds 13291c755af4SAl Viro mounted = lookup_mnt(path); 13301da177e4SLinus Torvalds if (mounted) { 13319393bd07SAl Viro dput(path->dentry); 13329393bd07SAl Viro mntput(path->mnt); 13339393bd07SAl Viro path->mnt = mounted; 13349393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 13351da177e4SLinus Torvalds return 1; 13361da177e4SLinus Torvalds } 13371da177e4SLinus Torvalds return 0; 13381da177e4SLinus Torvalds } 13394d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 13401da177e4SLinus Torvalds 13419875cf80SDavid Howells /* 13429deed3ebSAl Viro * Follow down to the covering mount currently visible to userspace. At each 13439deed3ebSAl Viro * point, the filesystem owning that dentry may be queried as to whether the 13449deed3ebSAl Viro * caller is permitted to proceed or not. 13459deed3ebSAl Viro */ 13469deed3ebSAl Viro int follow_down(struct path *path) 13479deed3ebSAl Viro { 13489deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 13499deed3ebSAl Viro bool jumped; 13509deed3ebSAl Viro int ret = traverse_mounts(path, &jumped, NULL, 0); 13519deed3ebSAl Viro 13529deed3ebSAl Viro if (path->mnt != mnt) 13539deed3ebSAl Viro mntput(mnt); 13549deed3ebSAl Viro return ret; 13559deed3ebSAl Viro } 13569deed3ebSAl Viro EXPORT_SYMBOL(follow_down); 13579deed3ebSAl Viro 13589deed3ebSAl Viro /* 1359287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1360287548e4SAl Viro * we meet a managed dentry that would need blocking. 13619875cf80SDavid Howells */ 13629875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1363254cf582SAl Viro struct inode **inode, unsigned *seqp) 13649875cf80SDavid Howells { 1365ea936aebSAl Viro struct dentry *dentry = path->dentry; 1366ea936aebSAl Viro unsigned int flags = dentry->d_flags; 1367ea936aebSAl Viro 1368ea936aebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) 1369ea936aebSAl Viro return true; 1370ea936aebSAl Viro 1371ea936aebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1372ea936aebSAl Viro return false; 1373ea936aebSAl Viro 137462a7375eSIan Kent for (;;) { 137562a7375eSIan Kent /* 137662a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 137762a7375eSIan Kent * that wants to block transit. 137862a7375eSIan Kent */ 1379ea936aebSAl Viro if (unlikely(flags & DCACHE_MANAGE_TRANSIT)) { 1380ea936aebSAl Viro int res = dentry->d_op->d_manage(path, true); 1381ea936aebSAl Viro if (res) 1382ea936aebSAl Viro return res == -EISDIR; 1383ea936aebSAl Viro flags = dentry->d_flags; 1384b8faf035SNeilBrown } 138562a7375eSIan Kent 1386ea936aebSAl Viro if (flags & DCACHE_MOUNTED) { 1387ea936aebSAl Viro struct mount *mounted = __lookup_mnt(path->mnt, dentry); 1388ea936aebSAl Viro if (mounted) { 1389c7105365SAl Viro path->mnt = &mounted->mnt; 1390ea936aebSAl Viro dentry = path->dentry = mounted->mnt.mnt_root; 1391a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1392ea936aebSAl Viro *seqp = read_seqcount_begin(&dentry->d_seq); 1393ea936aebSAl Viro *inode = dentry->d_inode; 139459430262SLinus Torvalds /* 1395ea936aebSAl Viro * We don't need to re-check ->d_seq after this 1396ea936aebSAl Viro * ->d_inode read - there will be an RCU delay 1397ea936aebSAl Viro * between mount hash removal and ->mnt_root 1398ea936aebSAl Viro * becoming unpinned. 139959430262SLinus Torvalds */ 1400ea936aebSAl Viro flags = dentry->d_flags; 1401ea936aebSAl Viro continue; 14029875cf80SDavid Howells } 1403ea936aebSAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1404ea936aebSAl Viro return false; 1405ea936aebSAl Viro } 1406ea936aebSAl Viro return !(flags & DCACHE_NEED_AUTOMOUNT); 1407ea936aebSAl Viro } 1408287548e4SAl Viro } 1409287548e4SAl Viro 1410db3c9adeSAl Viro static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, 1411db3c9adeSAl Viro struct path *path, struct inode **inode, 1412db3c9adeSAl Viro unsigned int *seqp) 1413bd7c4b50SAl Viro { 14149deed3ebSAl Viro bool jumped; 1415db3c9adeSAl Viro int ret; 1416bd7c4b50SAl Viro 1417db3c9adeSAl Viro path->mnt = nd->path.mnt; 1418db3c9adeSAl Viro path->dentry = dentry; 1419c153007bSAl Viro if (nd->flags & LOOKUP_RCU) { 1420c153007bSAl Viro unsigned int seq = *seqp; 1421c153007bSAl Viro if (unlikely(!*inode)) 1422c153007bSAl Viro return -ENOENT; 1423c153007bSAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 14249deed3ebSAl Viro return 0; 1425c153007bSAl Viro if (unlazy_child(nd, dentry, seq)) 1426c153007bSAl Viro return -ECHILD; 1427c153007bSAl Viro // *path might've been clobbered by __follow_mount_rcu() 1428c153007bSAl Viro path->mnt = nd->path.mnt; 1429c153007bSAl Viro path->dentry = dentry; 1430c153007bSAl Viro } 14319deed3ebSAl Viro ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags); 14329deed3ebSAl Viro if (jumped) { 14339deed3ebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 14349deed3ebSAl Viro ret = -EXDEV; 14359deed3ebSAl Viro else 14369deed3ebSAl Viro nd->flags |= LOOKUP_JUMPED; 14379deed3ebSAl Viro } 14389deed3ebSAl Viro if (unlikely(ret)) { 14399deed3ebSAl Viro dput(path->dentry); 14409deed3ebSAl Viro if (path->mnt != nd->path.mnt) 14419deed3ebSAl Viro mntput(path->mnt); 14429deed3ebSAl Viro } else { 1443bd7c4b50SAl Viro *inode = d_backing_inode(path->dentry); 1444bd7c4b50SAl Viro *seqp = 0; /* out of RCU mode, so the value doesn't matter */ 1445bd7c4b50SAl Viro } 1446bd7c4b50SAl Viro return ret; 1447bd7c4b50SAl Viro } 1448bd7c4b50SAl Viro 14499875cf80SDavid Howells /* 1450f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1451f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1452baa03890SNick Piggin */ 1453e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1454e3c13928SAl Viro struct dentry *dir, 14556c51e513SAl Viro unsigned int flags) 1456baa03890SNick Piggin { 1457a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1458bad61189SMiklos Szeredi if (dentry) { 1459a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1460bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 146174ff0ffcSAl Viro if (!error) 14625542aa2fSEric W. Biederman d_invalidate(dentry); 1463bad61189SMiklos Szeredi dput(dentry); 146474ff0ffcSAl Viro return ERR_PTR(error); 1465bad61189SMiklos Szeredi } 1466bad61189SMiklos Szeredi } 1467baa03890SNick Piggin return dentry; 1468baa03890SNick Piggin } 1469baa03890SNick Piggin 1470baa03890SNick Piggin /* 1471a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1472a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1473a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1474a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1475a03ece5fSAl Viro * at all. 147644396f4bSJosef Bacik */ 1477a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1478a03ece5fSAl Viro struct dentry *base, unsigned int flags) 147944396f4bSJosef Bacik { 1480a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 148144396f4bSJosef Bacik struct dentry *old; 1482a03ece5fSAl Viro struct inode *dir = base->d_inode; 1483a03ece5fSAl Viro 1484a03ece5fSAl Viro if (dentry) 1485a03ece5fSAl Viro return dentry; 148644396f4bSJosef Bacik 148744396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1488a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 148944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1490a03ece5fSAl Viro 1491a03ece5fSAl Viro dentry = d_alloc(base, name); 1492a03ece5fSAl Viro if (unlikely(!dentry)) 1493a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 149444396f4bSJosef Bacik 149572bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 149644396f4bSJosef Bacik if (unlikely(old)) { 149744396f4bSJosef Bacik dput(dentry); 149844396f4bSJosef Bacik dentry = old; 149944396f4bSJosef Bacik } 150044396f4bSJosef Bacik return dentry; 150144396f4bSJosef Bacik } 150244396f4bSJosef Bacik 150320e34357SAl Viro static struct dentry *lookup_fast(struct nameidata *nd, 150420e34357SAl Viro struct inode **inode, 1505254cf582SAl Viro unsigned *seqp) 15061da177e4SLinus Torvalds { 150731e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15085a18fff2SAl Viro int status = 1; 15099875cf80SDavid Howells 15103cac260aSAl Viro /* 1511b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15125d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15135d0f49c1SAl Viro * going to fall back to non-racy lookup. 1514b04f784eSNick Piggin */ 151531e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 151631e6b01fSNick Piggin unsigned seq; 1517da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15185d0f49c1SAl Viro if (unlikely(!dentry)) { 15194675ac39SAl Viro if (unlazy_walk(nd)) 152020e34357SAl Viro return ERR_PTR(-ECHILD); 152120e34357SAl Viro return NULL; 15225d0f49c1SAl Viro } 15235a18fff2SAl Viro 152412f8ad4bSLinus Torvalds /* 152512f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 152612f8ad4bSLinus Torvalds * the dentry name information from lookup. 152712f8ad4bSLinus Torvalds */ 152863afdfc7SDavid Howells *inode = d_backing_inode(dentry); 15295d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 153020e34357SAl Viro return ERR_PTR(-ECHILD); 153112f8ad4bSLinus Torvalds 153212f8ad4bSLinus Torvalds /* 153312f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 153412f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 153512f8ad4bSLinus Torvalds * 153612f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 153712f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 153812f8ad4bSLinus Torvalds */ 15395d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 154020e34357SAl Viro return ERR_PTR(-ECHILD); 15415a18fff2SAl Viro 1542254cf582SAl Viro *seqp = seq; 15434ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1544c153007bSAl Viro if (likely(status > 0)) 154520e34357SAl Viro return dentry; 15464675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 154720e34357SAl Viro return ERR_PTR(-ECHILD); 1548209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1549209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1550209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 15515a18fff2SAl Viro } else { 1552e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 155381e6f520SAl Viro if (unlikely(!dentry)) 155420e34357SAl Viro return NULL; 15554ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15565d0f49c1SAl Viro } 15575a18fff2SAl Viro if (unlikely(status <= 0)) { 1558e9742b53SAl Viro if (!status) 15595d0f49c1SAl Viro d_invalidate(dentry); 15605a18fff2SAl Viro dput(dentry); 156120e34357SAl Viro return ERR_PTR(status); 15625a18fff2SAl Viro } 156320e34357SAl Viro return dentry; 1564697f514dSMiklos Szeredi } 1565697f514dSMiklos Szeredi 1566697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 156788d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1568e3c13928SAl Viro struct dentry *dir, 1569e3c13928SAl Viro unsigned int flags) 1570697f514dSMiklos Szeredi { 157188d8331aSAl Viro struct dentry *dentry, *old; 15721936386eSAl Viro struct inode *inode = dir->d_inode; 1573d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 15741936386eSAl Viro 15751936386eSAl Viro /* Don't go there if it's already dead */ 157694bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 157788d8331aSAl Viro return ERR_PTR(-ENOENT); 157894bdd655SAl Viro again: 1579d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 158094bdd655SAl Viro if (IS_ERR(dentry)) 158188d8331aSAl Viro return dentry; 158294bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1583949a852eSAl Viro int error = d_revalidate(dentry, flags); 1584949a852eSAl Viro if (unlikely(error <= 0)) { 158594bdd655SAl Viro if (!error) { 1586949a852eSAl Viro d_invalidate(dentry); 1587949a852eSAl Viro dput(dentry); 158894bdd655SAl Viro goto again; 158994bdd655SAl Viro } 159094bdd655SAl Viro dput(dentry); 1591949a852eSAl Viro dentry = ERR_PTR(error); 1592949a852eSAl Viro } 159394bdd655SAl Viro } else { 15941936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 159585c7f810SAl Viro d_lookup_done(dentry); 15961936386eSAl Viro if (unlikely(old)) { 15971936386eSAl Viro dput(dentry); 15981936386eSAl Viro dentry = old; 1599949a852eSAl Viro } 1600949a852eSAl Viro } 1601e3c13928SAl Viro return dentry; 16021da177e4SLinus Torvalds } 16031da177e4SLinus Torvalds 160488d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 160588d8331aSAl Viro struct dentry *dir, 160688d8331aSAl Viro unsigned int flags) 160788d8331aSAl Viro { 160888d8331aSAl Viro struct inode *inode = dir->d_inode; 160988d8331aSAl Viro struct dentry *res; 161088d8331aSAl Viro inode_lock_shared(inode); 161188d8331aSAl Viro res = __lookup_slow(name, dir, flags); 161288d8331aSAl Viro inode_unlock_shared(inode); 161388d8331aSAl Viro return res; 161488d8331aSAl Viro } 161588d8331aSAl Viro 161652094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 161752094c8aSAl Viro { 161852094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 1619*47291baaSChristian Brauner int err = inode_permission(&init_user_ns, nd->inode, 1620*47291baaSChristian Brauner MAY_EXEC | MAY_NOT_BLOCK); 162152094c8aSAl Viro if (err != -ECHILD) 162252094c8aSAl Viro return err; 16234675ac39SAl Viro if (unlazy_walk(nd)) 162452094c8aSAl Viro return -ECHILD; 162552094c8aSAl Viro } 1626*47291baaSChristian Brauner return inode_permission(&init_user_ns, nd->inode, MAY_EXEC); 162752094c8aSAl Viro } 162852094c8aSAl Viro 162949055906SAl Viro static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq) 1630d63ff28fSAl Viro { 163149055906SAl Viro if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) 163249055906SAl Viro return -ELOOP; 16334542576bSAl Viro 16344542576bSAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 16354542576bSAl Viro return 0; 16364542576bSAl Viro if (likely(nd->stack != nd->internal)) 16374542576bSAl Viro return 0; 163860ef60c7SAl Viro if (likely(nd_alloc_stack(nd))) 163949055906SAl Viro return 0; 164060ef60c7SAl Viro 164160ef60c7SAl Viro if (nd->flags & LOOKUP_RCU) { 164260ef60c7SAl Viro // we need to grab link before we do unlazy. And we can't skip 164360ef60c7SAl Viro // unlazy even if we fail to grab the link - cleanup needs it 1644aef9404dSAl Viro bool grabbed_link = legitimize_path(nd, link, seq); 164560ef60c7SAl Viro 164660ef60c7SAl Viro if (unlazy_walk(nd) != 0 || !grabbed_link) 164760ef60c7SAl Viro return -ECHILD; 164860ef60c7SAl Viro 164960ef60c7SAl Viro if (nd_alloc_stack(nd)) 165060ef60c7SAl Viro return 0; 1651bc40aee0SAl Viro } 165260ef60c7SAl Viro return -ENOMEM; 165349055906SAl Viro } 165449055906SAl Viro 165549055906SAl Viro enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 165649055906SAl Viro 165749055906SAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 165849055906SAl Viro struct inode *inode, unsigned seq, int flags) 165949055906SAl Viro { 166049055906SAl Viro struct saved *last; 166149055906SAl Viro const char *res; 166249055906SAl Viro int error = reserve_stack(nd, link, seq); 166349055906SAl Viro 166449055906SAl Viro if (unlikely(error)) { 166549055906SAl Viro if (!(nd->flags & LOOKUP_RCU)) 1666cd179f44SAl Viro path_put(link); 166706708adbSAl Viro return ERR_PTR(error); 1668626de996SAl Viro } 1669ab104923SAl Viro last = nd->stack + nd->depth++; 16701cf2665bSAl Viro last->link = *link; 1671fceef393SAl Viro clear_delayed_call(&last->done); 16720450b2d1SAl Viro last->seq = seq; 1673ad6cc4c3SAl Viro 1674b1a81972SAl Viro if (flags & WALK_TRAILING) { 1675ad6cc4c3SAl Viro error = may_follow_link(nd, inode); 1676ad6cc4c3SAl Viro if (unlikely(error)) 1677ad6cc4c3SAl Viro return ERR_PTR(error); 1678ad6cc4c3SAl Viro } 1679ad6cc4c3SAl Viro 1680dab741e0SMattias Nissler if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS) || 1681dab741e0SMattias Nissler unlikely(link->mnt->mnt_flags & MNT_NOSYMFOLLOW)) 1682ad6cc4c3SAl Viro return ERR_PTR(-ELOOP); 1683ad6cc4c3SAl Viro 1684ad6cc4c3SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1685ad6cc4c3SAl Viro touch_atime(&last->link); 1686ad6cc4c3SAl Viro cond_resched(); 1687ad6cc4c3SAl Viro } else if (atime_needs_update(&last->link, inode)) { 1688ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1689ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1690ad6cc4c3SAl Viro touch_atime(&last->link); 1691ad6cc4c3SAl Viro } 1692ad6cc4c3SAl Viro 1693ad6cc4c3SAl Viro error = security_inode_follow_link(link->dentry, inode, 1694ad6cc4c3SAl Viro nd->flags & LOOKUP_RCU); 1695ad6cc4c3SAl Viro if (unlikely(error)) 1696ad6cc4c3SAl Viro return ERR_PTR(error); 1697ad6cc4c3SAl Viro 1698ad6cc4c3SAl Viro res = READ_ONCE(inode->i_link); 1699ad6cc4c3SAl Viro if (!res) { 1700ad6cc4c3SAl Viro const char * (*get)(struct dentry *, struct inode *, 1701ad6cc4c3SAl Viro struct delayed_call *); 1702ad6cc4c3SAl Viro get = inode->i_op->get_link; 1703ad6cc4c3SAl Viro if (nd->flags & LOOKUP_RCU) { 1704ad6cc4c3SAl Viro res = get(NULL, inode, &last->done); 1705ad6cc4c3SAl Viro if (res == ERR_PTR(-ECHILD)) { 1706ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1707ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1708ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1709ad6cc4c3SAl Viro } 1710ad6cc4c3SAl Viro } else { 1711ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1712ad6cc4c3SAl Viro } 1713ad6cc4c3SAl Viro if (!res) 1714ad6cc4c3SAl Viro goto all_done; 1715ad6cc4c3SAl Viro if (IS_ERR(res)) 1716ad6cc4c3SAl Viro return res; 1717ad6cc4c3SAl Viro } 1718ad6cc4c3SAl Viro if (*res == '/') { 1719ad6cc4c3SAl Viro error = nd_jump_root(nd); 1720ad6cc4c3SAl Viro if (unlikely(error)) 1721ad6cc4c3SAl Viro return ERR_PTR(error); 1722ad6cc4c3SAl Viro while (unlikely(*++res == '/')) 1723ad6cc4c3SAl Viro ; 1724ad6cc4c3SAl Viro } 1725ad6cc4c3SAl Viro if (*res) 1726ad6cc4c3SAl Viro return res; 1727ad6cc4c3SAl Viro all_done: // pure jump 1728ad6cc4c3SAl Viro put_link(nd); 1729ad6cc4c3SAl Viro return NULL; 1730d63ff28fSAl Viro } 1731d63ff28fSAl Viro 17323ddcd056SLinus Torvalds /* 17333ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17343ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17353ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17363ddcd056SLinus Torvalds * for the common case. 17373ddcd056SLinus Torvalds */ 1738b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1739cbae4d12SAl Viro struct dentry *dentry, struct inode *inode, unsigned seq) 17403ddcd056SLinus Torvalds { 1741cbae4d12SAl Viro struct path path; 1742cbae4d12SAl Viro int err = handle_mounts(nd, dentry, &path, &inode, &seq); 1743cbae4d12SAl Viro 1744cbae4d12SAl Viro if (err < 0) 1745b0417d2cSAl Viro return ERR_PTR(err); 1746cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 17478c4efe22SAl Viro ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) || 1748aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 17498f64fb1cSAl Viro /* not a symlink or should not follow */ 1750c99687a0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1751c99687a0SAl Viro dput(nd->path.dentry); 1752c99687a0SAl Viro if (nd->path.mnt != path.mnt) 1753c99687a0SAl Viro mntput(nd->path.mnt); 1754c99687a0SAl Viro } 1755c99687a0SAl Viro nd->path = path; 17568f64fb1cSAl Viro nd->inode = inode; 17578f64fb1cSAl Viro nd->seq = seq; 1758b0417d2cSAl Viro return NULL; 17598f64fb1cSAl Viro } 1760a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 176184f0cd9eSAl Viro /* make sure that d_is_symlink above matches inode */ 1762cbae4d12SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, seq)) 1763b0417d2cSAl Viro return ERR_PTR(-ECHILD); 176484f0cd9eSAl Viro } else { 176584f0cd9eSAl Viro if (path.mnt == nd->path.mnt) 176684f0cd9eSAl Viro mntget(path.mnt); 1767a7f77542SAl Viro } 1768b1a81972SAl Viro return pick_link(nd, &path, inode, seq, flags); 17693ddcd056SLinus Torvalds } 17703ddcd056SLinus Torvalds 1771c2df1968SAl Viro static struct dentry *follow_dotdot_rcu(struct nameidata *nd, 1772c2df1968SAl Viro struct inode **inodep, 1773c2df1968SAl Viro unsigned *seqp) 1774957dd41dSAl Viro { 177512487f30SAl Viro struct dentry *parent, *old; 1776957dd41dSAl Viro 177712487f30SAl Viro if (path_equal(&nd->path, &nd->root)) 177812487f30SAl Viro goto in_root; 177912487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 17807ef482faSAl Viro struct path path; 1781efe772d6SAl Viro unsigned seq; 17827ef482faSAl Viro if (!choose_mountpoint_rcu(real_mount(nd->path.mnt), 17837ef482faSAl Viro &nd->root, &path, &seq)) 178412487f30SAl Viro goto in_root; 1785efe772d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1786efe772d6SAl Viro return ERR_PTR(-ECHILD); 1787efe772d6SAl Viro nd->path = path; 1788efe772d6SAl Viro nd->inode = path.dentry->d_inode; 1789efe772d6SAl Viro nd->seq = seq; 1790efe772d6SAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1791efe772d6SAl Viro return ERR_PTR(-ECHILD); 1792efe772d6SAl Viro /* we know that mountpoint was pinned */ 1793957dd41dSAl Viro } 179412487f30SAl Viro old = nd->path.dentry; 179512487f30SAl Viro parent = old->d_parent; 179612487f30SAl Viro *inodep = parent->d_inode; 179712487f30SAl Viro *seqp = read_seqcount_begin(&parent->d_seq); 179812487f30SAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 179912487f30SAl Viro return ERR_PTR(-ECHILD); 180012487f30SAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) 180112487f30SAl Viro return ERR_PTR(-ECHILD); 180212487f30SAl Viro return parent; 180312487f30SAl Viro in_root: 1804efe772d6SAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1805efe772d6SAl Viro return ERR_PTR(-ECHILD); 1806957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 18077521f22bSAl Viro return ERR_PTR(-ECHILD); 1808c2df1968SAl Viro return NULL; 1809957dd41dSAl Viro } 1810957dd41dSAl Viro 1811c2df1968SAl Viro static struct dentry *follow_dotdot(struct nameidata *nd, 1812c2df1968SAl Viro struct inode **inodep, 1813c2df1968SAl Viro unsigned *seqp) 1814957dd41dSAl Viro { 181512487f30SAl Viro struct dentry *parent; 181612487f30SAl Viro 1817957dd41dSAl Viro if (path_equal(&nd->path, &nd->root)) 181812487f30SAl Viro goto in_root; 181912487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 18202aa38470SAl Viro struct path path; 18212aa38470SAl Viro 18222aa38470SAl Viro if (!choose_mountpoint(real_mount(nd->path.mnt), 18232aa38470SAl Viro &nd->root, &path)) 182412487f30SAl Viro goto in_root; 1825165200d6SAl Viro path_put(&nd->path); 1826165200d6SAl Viro nd->path = path; 18272aa38470SAl Viro nd->inode = path.dentry->d_inode; 1828165200d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1829165200d6SAl Viro return ERR_PTR(-EXDEV); 183012487f30SAl Viro } 1831957dd41dSAl Viro /* rare case of legitimate dget_parent()... */ 183212487f30SAl Viro parent = dget_parent(nd->path.dentry); 1833957dd41dSAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) { 1834957dd41dSAl Viro dput(parent); 18357521f22bSAl Viro return ERR_PTR(-ENOENT); 1836957dd41dSAl Viro } 1837c2df1968SAl Viro *seqp = 0; 1838c2df1968SAl Viro *inodep = parent->d_inode; 1839c2df1968SAl Viro return parent; 184012487f30SAl Viro 184112487f30SAl Viro in_root: 1842957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 18437521f22bSAl Viro return ERR_PTR(-EXDEV); 1844c2df1968SAl Viro dget(nd->path.dentry); 1845c2df1968SAl Viro return NULL; 1846957dd41dSAl Viro } 1847957dd41dSAl Viro 18487521f22bSAl Viro static const char *handle_dots(struct nameidata *nd, int type) 1849957dd41dSAl Viro { 1850957dd41dSAl Viro if (type == LAST_DOTDOT) { 18517521f22bSAl Viro const char *error = NULL; 1852c2df1968SAl Viro struct dentry *parent; 1853c2df1968SAl Viro struct inode *inode; 1854c2df1968SAl Viro unsigned seq; 1855957dd41dSAl Viro 1856957dd41dSAl Viro if (!nd->root.mnt) { 18577521f22bSAl Viro error = ERR_PTR(set_root(nd)); 1858957dd41dSAl Viro if (error) 1859957dd41dSAl Viro return error; 1860957dd41dSAl Viro } 1861957dd41dSAl Viro if (nd->flags & LOOKUP_RCU) 1862c2df1968SAl Viro parent = follow_dotdot_rcu(nd, &inode, &seq); 1863957dd41dSAl Viro else 1864c2df1968SAl Viro parent = follow_dotdot(nd, &inode, &seq); 1865c2df1968SAl Viro if (IS_ERR(parent)) 1866c2df1968SAl Viro return ERR_CAST(parent); 1867c2df1968SAl Viro if (unlikely(!parent)) 1868c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1869c2df1968SAl Viro nd->path.dentry, nd->inode, nd->seq); 1870c2df1968SAl Viro else 1871c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1872c2df1968SAl Viro parent, inode, seq); 1873c2df1968SAl Viro if (unlikely(error)) 1874957dd41dSAl Viro return error; 1875957dd41dSAl Viro 1876957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1877957dd41dSAl Viro /* 1878957dd41dSAl Viro * If there was a racing rename or mount along our 1879957dd41dSAl Viro * path, then we can't be sure that ".." hasn't jumped 1880957dd41dSAl Viro * above nd->root (and so userspace should retry or use 1881957dd41dSAl Viro * some fallback). 1882957dd41dSAl Viro */ 1883957dd41dSAl Viro smp_rmb(); 1884957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq))) 18857521f22bSAl Viro return ERR_PTR(-EAGAIN); 1886957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq))) 18877521f22bSAl Viro return ERR_PTR(-EAGAIN); 1888957dd41dSAl Viro } 1889957dd41dSAl Viro } 18907521f22bSAl Viro return NULL; 1891957dd41dSAl Viro } 1892957dd41dSAl Viro 189392d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1894ce57dfc1SAl Viro { 1895db3c9adeSAl Viro struct dentry *dentry; 1896ce57dfc1SAl Viro struct inode *inode; 1897254cf582SAl Viro unsigned seq; 1898ce57dfc1SAl Viro /* 1899ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1900ce57dfc1SAl Viro * to be able to know about the current root directory and 1901ce57dfc1SAl Viro * parent relationships. 1902ce57dfc1SAl Viro */ 19034693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 19041c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 19054693a547SAl Viro put_link(nd); 19067521f22bSAl Viro return handle_dots(nd, nd->last_type); 19074693a547SAl Viro } 190820e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 190920e34357SAl Viro if (IS_ERR(dentry)) 191092d27016SAl Viro return ERR_CAST(dentry); 191120e34357SAl Viro if (unlikely(!dentry)) { 1912db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 1913db3c9adeSAl Viro if (IS_ERR(dentry)) 191492d27016SAl Viro return ERR_CAST(dentry); 191520e34357SAl Viro } 191656676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 191756676ec3SAl Viro put_link(nd); 1918b0417d2cSAl Viro return step_into(nd, flags, dentry, inode, seq); 1919ce57dfc1SAl Viro } 1920ce57dfc1SAl Viro 19211da177e4SLinus Torvalds /* 1922bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1923bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1924bfcfaa77SLinus Torvalds * 1925bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1926bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1927bfcfaa77SLinus Torvalds * fast. 1928bfcfaa77SLinus Torvalds * 1929bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1930bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1931bfcfaa77SLinus Torvalds * crossing operation. 1932bfcfaa77SLinus Torvalds * 1933bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1934bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1935bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1936bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1937bfcfaa77SLinus Torvalds */ 1938bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1939bfcfaa77SLinus Torvalds 1940f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1941bfcfaa77SLinus Torvalds 1942468a9428SGeorge Spelvin #ifdef HASH_MIX 1943bfcfaa77SLinus Torvalds 1944468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1945468a9428SGeorge Spelvin 1946468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 19472a18da7aSGeorge Spelvin /* 19482a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 19492a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 19502a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 19512a18da7aSGeorge Spelvin * and no temporaries. 19522a18da7aSGeorge Spelvin * 19532a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 19542a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 19552a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 19562a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 19572a18da7aSGeorge Spelvin * 19582a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 19592a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 19602a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 19612a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 19622a18da7aSGeorge Spelvin * 19632a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 19642a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 19652a18da7aSGeorge Spelvin * toggling any given output bit. 19662a18da7aSGeorge Spelvin * 19672a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 19682a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19692a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 19702a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 19712a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 19722a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 19732a18da7aSGeorge Spelvin * Perfect: 8192 258048 19742a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 19752a18da7aSGeorge Spelvin */ 19762a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19772a18da7aSGeorge Spelvin ( x ^= (a), \ 19782a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 19792a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 19802a18da7aSGeorge Spelvin y *= 9 ) 1981bfcfaa77SLinus Torvalds 19820fed3ac8SGeorge Spelvin /* 19832a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 19842a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 19852a18da7aSGeorge Spelvin * work done before the hash value is used. 19860fed3ac8SGeorge Spelvin */ 19872a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19880fed3ac8SGeorge Spelvin { 19892a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 19902a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 19912a18da7aSGeorge Spelvin return y >> 32; 19920fed3ac8SGeorge Spelvin } 19930fed3ac8SGeorge Spelvin 1994bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1995bfcfaa77SLinus Torvalds 19962a18da7aSGeorge Spelvin /* 19972a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 19982a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19992a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 20002a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 20012a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 20022a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 20032a18da7aSGeorge Spelvin * Perfect: 2048 31744 20042a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 20052a18da7aSGeorge Spelvin */ 20062a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 20072a18da7aSGeorge Spelvin ( x ^= (a), \ 20082a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 20092a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 20102a18da7aSGeorge Spelvin y *= 9 ) 2011bfcfaa77SLinus Torvalds 20122a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 20130fed3ac8SGeorge Spelvin { 20142a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 20152a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 20160fed3ac8SGeorge Spelvin } 20170fed3ac8SGeorge Spelvin 2018bfcfaa77SLinus Torvalds #endif 2019bfcfaa77SLinus Torvalds 20202a18da7aSGeorge Spelvin /* 20212a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 20222a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 20232a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 20242a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 20252a18da7aSGeorge Spelvin * finds the delimiter after the name. 20262a18da7aSGeorge Spelvin */ 20278387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 2028bfcfaa77SLinus Torvalds { 20298387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 2030bfcfaa77SLinus Torvalds 2031bfcfaa77SLinus Torvalds for (;;) { 2032fcfd2fbfSGeorge Spelvin if (!len) 2033fcfd2fbfSGeorge Spelvin goto done; 2034e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 2035bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 2036bfcfaa77SLinus Torvalds break; 20372a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2038bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 2039bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 2040bfcfaa77SLinus Torvalds } 20412a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 2042bfcfaa77SLinus Torvalds done: 20432a18da7aSGeorge Spelvin return fold_hash(x, y); 2044bfcfaa77SLinus Torvalds } 2045bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 2046bfcfaa77SLinus Torvalds 2047fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20488387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2049fcfd2fbfSGeorge Spelvin { 20508387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 20518387ff25SLinus Torvalds unsigned long adata, mask, len; 2052fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2053fcfd2fbfSGeorge Spelvin 20548387ff25SLinus Torvalds len = 0; 20558387ff25SLinus Torvalds goto inside; 20568387ff25SLinus Torvalds 2057fcfd2fbfSGeorge Spelvin do { 20582a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2059fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 20608387ff25SLinus Torvalds inside: 2061fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2062fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2063fcfd2fbfSGeorge Spelvin 2064fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2065fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 20662a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2067fcfd2fbfSGeorge Spelvin 20682a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2069fcfd2fbfSGeorge Spelvin } 2070fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2071fcfd2fbfSGeorge Spelvin 2072bfcfaa77SLinus Torvalds /* 2073bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2074d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2075bfcfaa77SLinus Torvalds */ 20768387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2077bfcfaa77SLinus Torvalds { 20788387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 20798387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 208036126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2081bfcfaa77SLinus Torvalds 20828387ff25SLinus Torvalds len = 0; 20838387ff25SLinus Torvalds goto inside; 20848387ff25SLinus Torvalds 2085bfcfaa77SLinus Torvalds do { 20862a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2087bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20888387ff25SLinus Torvalds inside: 2089e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 209036126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 209136126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2092bfcfaa77SLinus Torvalds 209336126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 209436126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 209536126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20962a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 209736126f8fSLinus Torvalds 20982a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2099bfcfaa77SLinus Torvalds } 2100bfcfaa77SLinus Torvalds 21012a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2102bfcfaa77SLinus Torvalds 2103fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 21048387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 21050145acc2SLinus Torvalds { 21068387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 21070145acc2SLinus Torvalds while (len--) 2108fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 21090145acc2SLinus Torvalds return end_name_hash(hash); 21100145acc2SLinus Torvalds } 2111ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 21120145acc2SLinus Torvalds 2113fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 21148387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2115fcfd2fbfSGeorge Spelvin { 21168387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2117fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2118fcfd2fbfSGeorge Spelvin 2119fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2120e0ab7af9SGeorge Spelvin while (c) { 2121fcfd2fbfSGeorge Spelvin len++; 2122fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2123fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2124e0ab7af9SGeorge Spelvin } 2125fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2126fcfd2fbfSGeorge Spelvin } 2127f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2128fcfd2fbfSGeorge Spelvin 21293ddcd056SLinus Torvalds /* 2130200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2131200e9ef7SLinus Torvalds * one character. 2132200e9ef7SLinus Torvalds */ 21338387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2134200e9ef7SLinus Torvalds { 21358387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2136200e9ef7SLinus Torvalds unsigned long len = 0, c; 2137200e9ef7SLinus Torvalds 2138200e9ef7SLinus Torvalds c = (unsigned char)*name; 2139200e9ef7SLinus Torvalds do { 2140200e9ef7SLinus Torvalds len++; 2141200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2142200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2143200e9ef7SLinus Torvalds } while (c && c != '/'); 2144d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2145200e9ef7SLinus Torvalds } 2146200e9ef7SLinus Torvalds 2147bfcfaa77SLinus Torvalds #endif 2148bfcfaa77SLinus Torvalds 2149200e9ef7SLinus Torvalds /* 21501da177e4SLinus Torvalds * Name resolution. 2151ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2152ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 21531da177e4SLinus Torvalds * 2154ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2155ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 21561da177e4SLinus Torvalds */ 21576de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 21581da177e4SLinus Torvalds { 2159d8d4611aSAl Viro int depth = 0; // depth <= nd->depth 21601da177e4SLinus Torvalds int err; 21611da177e4SLinus Torvalds 2162b4c03536SAl Viro nd->last_type = LAST_ROOT; 2163c108837eSAl Viro nd->flags |= LOOKUP_PARENT; 21649b5858e9SAl Viro if (IS_ERR(name)) 21659b5858e9SAl Viro return PTR_ERR(name); 21661da177e4SLinus Torvalds while (*name=='/') 21671da177e4SLinus Torvalds name++; 21681a97d899SAl Viro if (!*name) { 21691a97d899SAl Viro nd->dir_mode = 0; // short-circuit the 'hardening' idiocy 21709e18f10aSAl Viro return 0; 21711a97d899SAl Viro } 21721da177e4SLinus Torvalds 21731da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 21741da177e4SLinus Torvalds for(;;) { 217592d27016SAl Viro const char *link; 2176d6bb3e90SLinus Torvalds u64 hash_len; 2177fe479a58SAl Viro int type; 21781da177e4SLinus Torvalds 217952094c8aSAl Viro err = may_lookup(nd); 21801da177e4SLinus Torvalds if (err) 21813595e234SAl Viro return err; 21821da177e4SLinus Torvalds 21838387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 21841da177e4SLinus Torvalds 2185fe479a58SAl Viro type = LAST_NORM; 2186d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2187fe479a58SAl Viro case 2: 2188200e9ef7SLinus Torvalds if (name[1] == '.') { 2189fe479a58SAl Viro type = LAST_DOTDOT; 219016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 219116c2cd71SAl Viro } 2192fe479a58SAl Viro break; 2193fe479a58SAl Viro case 1: 2194fe479a58SAl Viro type = LAST_DOT; 2195fe479a58SAl Viro } 21965a202bcdSAl Viro if (likely(type == LAST_NORM)) { 21975a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 219816c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 21995a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2200a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2201da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 22025a202bcdSAl Viro if (err < 0) 22033595e234SAl Viro return err; 2204d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2205d6bb3e90SLinus Torvalds name = this.name; 22065a202bcdSAl Viro } 22075a202bcdSAl Viro } 2208fe479a58SAl Viro 2209d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2210d6bb3e90SLinus Torvalds nd->last.name = name; 22115f4a6a69SAl Viro nd->last_type = type; 22125f4a6a69SAl Viro 2213d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2214d6bb3e90SLinus Torvalds if (!*name) 2215bdf6cbf1SAl Viro goto OK; 2216200e9ef7SLinus Torvalds /* 2217200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2218200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2219200e9ef7SLinus Torvalds */ 2220200e9ef7SLinus Torvalds do { 2221d6bb3e90SLinus Torvalds name++; 2222d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 22238620c238SAl Viro if (unlikely(!*name)) { 22248620c238SAl Viro OK: 2225d8d4611aSAl Viro /* pathname or trailing symlink, done */ 2226c108837eSAl Viro if (!depth) { 22270f705953SAl Viro nd->dir_uid = nd->inode->i_uid; 22280f705953SAl Viro nd->dir_mode = nd->inode->i_mode; 2229c108837eSAl Viro nd->flags &= ~LOOKUP_PARENT; 22308620c238SAl Viro return 0; 2231c108837eSAl Viro } 22328620c238SAl Viro /* last component of nested symlink */ 2233d8d4611aSAl Viro name = nd->stack[--depth].name; 22348c4efe22SAl Viro link = walk_component(nd, 0); 22351c4ff1a8SAl Viro } else { 22361c4ff1a8SAl Viro /* not the last component */ 22378c4efe22SAl Viro link = walk_component(nd, WALK_MORE); 22388620c238SAl Viro } 223992d27016SAl Viro if (unlikely(link)) { 224092d27016SAl Viro if (IS_ERR(link)) 224192d27016SAl Viro return PTR_ERR(link); 224292d27016SAl Viro /* a symlink to follow */ 2243d8d4611aSAl Viro nd->stack[depth++].name = name; 224492d27016SAl Viro name = link; 22459e18f10aSAl Viro continue; 224648c8b0c5SAl Viro } 224797242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 224897242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 22494675ac39SAl Viro if (unlazy_walk(nd)) 225097242f99SAl Viro return -ECHILD; 225197242f99SAl Viro } 22523595e234SAl Viro return -ENOTDIR; 22535f4a6a69SAl Viro } 2254ce57dfc1SAl Viro } 225597242f99SAl Viro } 22561da177e4SLinus Torvalds 2257edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2258c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 225931e6b01fSNick Piggin { 2260740a1678SAleksa Sarai int error; 2261c8a53ee5SAl Viro const char *s = nd->name->name; 226231e6b01fSNick Piggin 2263c0eb027eSLinus Torvalds if (!*s) 2264c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2265edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2266edc2b1daSAl Viro rcu_read_lock(); 2267c0eb027eSLinus Torvalds 2268c108837eSAl Viro nd->flags = flags | LOOKUP_JUMPED; 226931e6b01fSNick Piggin nd->depth = 0; 2270ab87f9a5SAleksa Sarai 2271ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2272ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2273ab87f9a5SAleksa Sarai smp_rmb(); 2274ab87f9a5SAleksa Sarai 22755b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2276b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2277b18825a7SDavid Howells struct inode *inode = root->d_inode; 227893893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2279368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 22805b6ca027SAl Viro nd->path = nd->root; 22815b6ca027SAl Viro nd->inode = inode; 22825b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2283ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22848f47a016SAl Viro nd->root_seq = nd->seq; 22855b6ca027SAl Viro } else { 22865b6ca027SAl Viro path_get(&nd->path); 22875b6ca027SAl Viro } 2288368ee9baSAl Viro return s; 22895b6ca027SAl Viro } 22905b6ca027SAl Viro 229131e6b01fSNick Piggin nd->root.mnt = NULL; 2292248fb5b9SAl Viro nd->path.mnt = NULL; 2293248fb5b9SAl Viro nd->path.dentry = NULL; 229431e6b01fSNick Piggin 22958db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 22968db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2297740a1678SAleksa Sarai error = nd_jump_root(nd); 2298740a1678SAleksa Sarai if (unlikely(error)) 2299740a1678SAleksa Sarai return ERR_PTR(error); 2300ef55d917SAl Viro return s; 23018db52c7eSAleksa Sarai } 23028db52c7eSAleksa Sarai 23038db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 23048db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2305e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 230631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2307c28cc364SNick Piggin unsigned seq; 230831e6b01fSNick Piggin 2309c28cc364SNick Piggin do { 2310c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 231131e6b01fSNick Piggin nd->path = fs->pwd; 2312ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2313c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2314c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2315e41f7d4eSAl Viro } else { 2316e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2317ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2318e41f7d4eSAl Viro } 231931e6b01fSNick Piggin } else { 2320582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2321c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 232231e6b01fSNick Piggin struct dentry *dentry; 232331e6b01fSNick Piggin 23242903ff01SAl Viro if (!f.file) 2325368ee9baSAl Viro return ERR_PTR(-EBADF); 232631e6b01fSNick Piggin 23272903ff01SAl Viro dentry = f.file->f_path.dentry; 232831e6b01fSNick Piggin 2329edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 23302903ff01SAl Viro fdput(f); 2331368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2332f52e0c11SAl Viro } 23332903ff01SAl Viro 23342903ff01SAl Viro nd->path = f.file->f_path; 2335e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 233634a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 233734a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 23385590ff0dSUlrich Drepper } else { 23392903ff01SAl Viro path_get(&nd->path); 234034a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 23411da177e4SLinus Torvalds } 234234a26b99SAl Viro fdput(f); 2343e41f7d4eSAl Viro } 23448db52c7eSAleksa Sarai 2345adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2346adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2347adb21d2bSAleksa Sarai nd->root = nd->path; 2348adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2349adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2350adb21d2bSAleksa Sarai } else { 2351adb21d2bSAleksa Sarai path_get(&nd->root); 2352adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2353adb21d2bSAleksa Sarai } 2354adb21d2bSAleksa Sarai } 2355adb21d2bSAleksa Sarai return s; 23569b4a9b14SAl Viro } 23579b4a9b14SAl Viro 23581ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 235995fa25d9SAl Viro { 2360bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2361bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2362bd92d7feSAl Viro 2363c108837eSAl Viro return walk_component(nd, WALK_TRAILING); 2364bd92d7feSAl Viro } 2365bd92d7feSAl Viro 23664f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 23674f757f3cSAl Viro { 2368c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2369db3c9adeSAl Viro dget(nd->path.dentry); 2370b0417d2cSAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, 2371b0417d2cSAl Viro nd->path.dentry, nd->inode, nd->seq)); 23724f757f3cSAl Viro } 23734f757f3cSAl Viro 23749b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2375c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 23769b4a9b14SAl Viro { 2377c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2378bd92d7feSAl Viro int err; 237931e6b01fSNick Piggin 23809b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 23814f757f3cSAl Viro err = handle_lookup_down(nd); 23825f336e72SAl Viro if (unlikely(err < 0)) 23835f336e72SAl Viro s = ERR_PTR(err); 23844f757f3cSAl Viro } 23854f757f3cSAl Viro 23861ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 23871ccac622SAl Viro (s = lookup_last(nd)) != NULL) 23881ccac622SAl Viro ; 23899f1fafeeSAl Viro if (!err) 23909f1fafeeSAl Viro err = complete_walk(nd); 2391bd92d7feSAl Viro 2392deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2393deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2394bd23a539SAl Viro err = -ENOTDIR; 2395161aff1dSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 2396161aff1dSAl Viro err = handle_lookup_down(nd); 2397161aff1dSAl Viro nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please... 2398161aff1dSAl Viro } 2399625b6d10SAl Viro if (!err) { 2400625b6d10SAl Viro *path = nd->path; 2401625b6d10SAl Viro nd->path.mnt = NULL; 2402625b6d10SAl Viro nd->path.dentry = NULL; 2403625b6d10SAl Viro } 2404deb106c6SAl Viro terminate_walk(nd); 2405bd92d7feSAl Viro return err; 240631e6b01fSNick Piggin } 240731e6b01fSNick Piggin 240831d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 24099ad1aaa6SAl Viro struct path *path, struct path *root) 2410873f1eedSJeff Layton { 2411894bc8c4SAl Viro int retval; 24129883d185SAl Viro struct nameidata nd; 2413abc9f5beSAl Viro if (IS_ERR(name)) 2414abc9f5beSAl Viro return PTR_ERR(name); 24159ad1aaa6SAl Viro if (unlikely(root)) { 24169ad1aaa6SAl Viro nd.root = *root; 24179ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 24189ad1aaa6SAl Viro } 24199883d185SAl Viro set_nameidata(&nd, dfd, name); 2420c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2421873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2422c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2423873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2424c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2425873f1eedSJeff Layton 2426873f1eedSJeff Layton if (likely(!retval)) 2427161aff1dSAl Viro audit_inode(name, path->dentry, 2428161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 24299883d185SAl Viro restore_nameidata(); 2430e4bd1c1aSAl Viro putname(name); 2431873f1eedSJeff Layton return retval; 2432873f1eedSJeff Layton } 2433873f1eedSJeff Layton 24348bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2435c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2436391172c4SAl Viro struct path *parent) 24378bcb77faSAl Viro { 2438c8a53ee5SAl Viro const char *s = path_init(nd, flags); 24399b5858e9SAl Viro int err = link_path_walk(s, nd); 24408bcb77faSAl Viro if (!err) 24418bcb77faSAl Viro err = complete_walk(nd); 2442391172c4SAl Viro if (!err) { 2443391172c4SAl Viro *parent = nd->path; 2444391172c4SAl Viro nd->path.mnt = NULL; 2445391172c4SAl Viro nd->path.dentry = NULL; 2446391172c4SAl Viro } 2447deb106c6SAl Viro terminate_walk(nd); 24488bcb77faSAl Viro return err; 24498bcb77faSAl Viro } 24508bcb77faSAl Viro 24515c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2452391172c4SAl Viro unsigned int flags, struct path *parent, 2453391172c4SAl Viro struct qstr *last, int *type) 24548bcb77faSAl Viro { 24558bcb77faSAl Viro int retval; 24569883d185SAl Viro struct nameidata nd; 24578bcb77faSAl Viro 24585c31b6ceSAl Viro if (IS_ERR(name)) 24595c31b6ceSAl Viro return name; 24609883d185SAl Viro set_nameidata(&nd, dfd, name); 2461c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 24628bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2463c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 24648bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2465c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2466391172c4SAl Viro if (likely(!retval)) { 2467391172c4SAl Viro *last = nd.last; 2468391172c4SAl Viro *type = nd.last_type; 2469c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 24705c31b6ceSAl Viro } else { 24715c31b6ceSAl Viro putname(name); 24725c31b6ceSAl Viro name = ERR_PTR(retval); 2473391172c4SAl Viro } 24749883d185SAl Viro restore_nameidata(); 24755c31b6ceSAl Viro return name; 24768bcb77faSAl Viro } 24778bcb77faSAl Viro 247879714f72SAl Viro /* does lookup, returns the object with parent locked */ 247979714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 24805590ff0dSUlrich Drepper { 24815c31b6ceSAl Viro struct filename *filename; 24825c31b6ceSAl Viro struct dentry *d; 2483391172c4SAl Viro struct qstr last; 2484391172c4SAl Viro int type; 248551689104SPaul Moore 24865c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24875c31b6ceSAl Viro &last, &type); 248851689104SPaul Moore if (IS_ERR(filename)) 248951689104SPaul Moore return ERR_CAST(filename); 24905c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2491391172c4SAl Viro path_put(path); 24925c31b6ceSAl Viro putname(filename); 24935c31b6ceSAl Viro return ERR_PTR(-EINVAL); 249479714f72SAl Viro } 24955955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2496391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 249779714f72SAl Viro if (IS_ERR(d)) { 24985955102cSAl Viro inode_unlock(path->dentry->d_inode); 2499391172c4SAl Viro path_put(path); 250079714f72SAl Viro } 250151689104SPaul Moore putname(filename); 250279714f72SAl Viro return d; 25035590ff0dSUlrich Drepper } 25045590ff0dSUlrich Drepper 2505d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2506d1811465SAl Viro { 2507abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2508abc9f5beSAl Viro flags, path, NULL); 2509d1811465SAl Viro } 25104d359507SAl Viro EXPORT_SYMBOL(kern_path); 2511d1811465SAl Viro 251216f18200SJosef 'Jeff' Sipek /** 251316f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 251416f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 251516f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 251616f18200SJosef 'Jeff' Sipek * @name: pointer to file name 251716f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2518e0a01249SAl Viro * @path: pointer to struct path to fill 251916f18200SJosef 'Jeff' Sipek */ 252016f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 252116f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2522e0a01249SAl Viro struct path *path) 252316f18200SJosef 'Jeff' Sipek { 25249ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 25259ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2526abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2527abc9f5beSAl Viro flags , path, &root); 252816f18200SJosef 'Jeff' Sipek } 25294d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 253016f18200SJosef 'Jeff' Sipek 25313c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 25323c95f0dcSAl Viro int len, struct qstr *this) 25333c95f0dcSAl Viro { 25343c95f0dcSAl Viro this->name = name; 25353c95f0dcSAl Viro this->len = len; 25363c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 25373c95f0dcSAl Viro if (!len) 25383c95f0dcSAl Viro return -EACCES; 25393c95f0dcSAl Viro 25403c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 25413c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 25423c95f0dcSAl Viro return -EACCES; 25433c95f0dcSAl Viro } 25443c95f0dcSAl Viro 25453c95f0dcSAl Viro while (len--) { 25463c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 25473c95f0dcSAl Viro if (c == '/' || c == '\0') 25483c95f0dcSAl Viro return -EACCES; 25493c95f0dcSAl Viro } 25503c95f0dcSAl Viro /* 25513c95f0dcSAl Viro * See if the low-level filesystem might want 25523c95f0dcSAl Viro * to use its own hash.. 25533c95f0dcSAl Viro */ 25543c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 25553c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 25563c95f0dcSAl Viro if (err < 0) 25573c95f0dcSAl Viro return err; 25583c95f0dcSAl Viro } 25593c95f0dcSAl Viro 2560*47291baaSChristian Brauner return inode_permission(&init_user_ns, base->d_inode, MAY_EXEC); 25613c95f0dcSAl Viro } 25623c95f0dcSAl Viro 2563eead1911SChristoph Hellwig /** 25640da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 25650da0b7fdSDavid Howells * @name: pathname component to lookup 25660da0b7fdSDavid Howells * @base: base directory to lookup from 25670da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 25680da0b7fdSDavid Howells * 25690da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 25700da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 25710da0b7fdSDavid Howells * 25720da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 25730da0b7fdSDavid Howells * not be called by generic code. 25740da0b7fdSDavid Howells * 25750da0b7fdSDavid Howells * The caller must hold base->i_mutex. 25760da0b7fdSDavid Howells */ 25770da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 25780da0b7fdSDavid Howells { 25790da0b7fdSDavid Howells struct qstr this; 25800da0b7fdSDavid Howells int err; 25810da0b7fdSDavid Howells 25820da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25830da0b7fdSDavid Howells 25840da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 25850da0b7fdSDavid Howells if (err) 25860da0b7fdSDavid Howells return ERR_PTR(err); 25870da0b7fdSDavid Howells 25880da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25890da0b7fdSDavid Howells } 25900da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25910da0b7fdSDavid Howells 25920da0b7fdSDavid Howells /** 2593a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2594eead1911SChristoph Hellwig * @name: pathname component to lookup 2595eead1911SChristoph Hellwig * @base: base directory to lookup from 2596eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2597eead1911SChristoph Hellwig * 2598a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25999e7543e9SAl Viro * not be called by generic code. 2600bbddca8eSNeilBrown * 2601bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2602eead1911SChristoph Hellwig */ 2603057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2604057f6c01SJames Morris { 26058613a209SAl Viro struct dentry *dentry; 2606057f6c01SJames Morris struct qstr this; 2607cda309deSMiklos Szeredi int err; 2608057f6c01SJames Morris 26095955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 26102f9092e1SDavid Woodhouse 26113c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2612cda309deSMiklos Szeredi if (err) 2613cda309deSMiklos Szeredi return ERR_PTR(err); 2614cda309deSMiklos Szeredi 26158613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 26168613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2617057f6c01SJames Morris } 26184d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2619057f6c01SJames Morris 2620bbddca8eSNeilBrown /** 2621bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2622bbddca8eSNeilBrown * @name: pathname component to lookup 2623bbddca8eSNeilBrown * @base: base directory to lookup from 2624bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2625bbddca8eSNeilBrown * 2626bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2627bbddca8eSNeilBrown * not be called by generic code. 2628bbddca8eSNeilBrown * 2629bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2630bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2631bbddca8eSNeilBrown */ 2632bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2633bbddca8eSNeilBrown struct dentry *base, int len) 2634bbddca8eSNeilBrown { 2635bbddca8eSNeilBrown struct qstr this; 2636bbddca8eSNeilBrown int err; 263720d00ee8SLinus Torvalds struct dentry *ret; 2638bbddca8eSNeilBrown 26393c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2640bbddca8eSNeilBrown if (err) 2641bbddca8eSNeilBrown return ERR_PTR(err); 2642bbddca8eSNeilBrown 264320d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 264420d00ee8SLinus Torvalds if (!ret) 264520d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 264620d00ee8SLinus Torvalds return ret; 2647bbddca8eSNeilBrown } 2648bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2649bbddca8eSNeilBrown 26506c2d4798SAl Viro /* 26516c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 26526c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 26536c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 26546c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 26556c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 26566c2d4798SAl Viro * this one avoids such problems. 26576c2d4798SAl Viro */ 26586c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 26596c2d4798SAl Viro struct dentry *base, int len) 26606c2d4798SAl Viro { 26616c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 26622fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 26636c2d4798SAl Viro dput(ret); 26646c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 26656c2d4798SAl Viro } 26666c2d4798SAl Viro return ret; 26676c2d4798SAl Viro } 26686c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 26696c2d4798SAl Viro 2670eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2671eedf265aSEric W. Biederman int path_pts(struct path *path) 2672eedf265aSEric W. Biederman { 2673eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2674eedf265aSEric W. Biederman * the input path. 2675eedf265aSEric W. Biederman */ 2676a6a7eb76SAl Viro struct dentry *parent = dget_parent(path->dentry); 2677a6a7eb76SAl Viro struct dentry *child; 267819f6028aSAl Viro struct qstr this = QSTR_INIT("pts", 3); 2679eedf265aSEric W. Biederman 2680a6a7eb76SAl Viro if (unlikely(!path_connected(path->mnt, parent))) { 2681a6a7eb76SAl Viro dput(parent); 268263b27720SAl Viro return -ENOENT; 2683a6a7eb76SAl Viro } 268463b27720SAl Viro dput(path->dentry); 268563b27720SAl Viro path->dentry = parent; 2686eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2687eedf265aSEric W. Biederman if (!child) 2688eedf265aSEric W. Biederman return -ENOENT; 2689eedf265aSEric W. Biederman 2690eedf265aSEric W. Biederman path->dentry = child; 2691eedf265aSEric W. Biederman dput(parent); 269219f6028aSAl Viro follow_down(path); 2693eedf265aSEric W. Biederman return 0; 2694eedf265aSEric W. Biederman } 2695eedf265aSEric W. Biederman #endif 2696eedf265aSEric W. Biederman 26971fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26981fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26991da177e4SLinus Torvalds { 2700abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2701abc9f5beSAl Viro flags, path, NULL); 27021da177e4SLinus Torvalds } 2703b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 27041fa1e7f6SAndy Whitcroft 2705cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27061da177e4SLinus Torvalds { 27078e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2708da9592edSDavid Howells 27098e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27101da177e4SLinus Torvalds return 0; 27118e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27121da177e4SLinus Torvalds return 0; 27130558c1bfSChristian Brauner return !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FOWNER); 27141da177e4SLinus Torvalds } 2715cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27161da177e4SLinus Torvalds 27171da177e4SLinus Torvalds /* 27181da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27191da177e4SLinus Torvalds * whether the type of victim is right. 27201da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27211da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27221da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27231da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27241da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27251da177e4SLinus Torvalds * a. be owner of dir, or 27261da177e4SLinus Torvalds * b. be owner of victim, or 27271da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27281da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27291da177e4SLinus Torvalds * links pointing to it. 27300bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27310bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27320bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27330bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27340bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27351da177e4SLinus Torvalds * nfs_async_unlink(). 27361da177e4SLinus Torvalds */ 2737b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27381da177e4SLinus Torvalds { 273963afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27401da177e4SLinus Torvalds int error; 27411da177e4SLinus Torvalds 2742b18825a7SDavid Howells if (d_is_negative(victim)) 27431da177e4SLinus Torvalds return -ENOENT; 2744b18825a7SDavid Howells BUG_ON(!inode); 27451da177e4SLinus Torvalds 27461da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2747593d1ce8SEric W. Biederman 2748593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2749593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2750593d1ce8SEric W. Biederman return -EOVERFLOW; 2751593d1ce8SEric W. Biederman 27524fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27531da177e4SLinus Torvalds 2754*47291baaSChristian Brauner error = inode_permission(&init_user_ns, dir, MAY_WRITE | MAY_EXEC); 27551da177e4SLinus Torvalds if (error) 27561da177e4SLinus Torvalds return error; 27571da177e4SLinus Torvalds if (IS_APPEND(dir)) 27581da177e4SLinus Torvalds return -EPERM; 2759b18825a7SDavid Howells 2760b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27610bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27621da177e4SLinus Torvalds return -EPERM; 27631da177e4SLinus Torvalds if (isdir) { 276444b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27651da177e4SLinus Torvalds return -ENOTDIR; 27661da177e4SLinus Torvalds if (IS_ROOT(victim)) 27671da177e4SLinus Torvalds return -EBUSY; 276844b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27691da177e4SLinus Torvalds return -EISDIR; 27701da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27711da177e4SLinus Torvalds return -ENOENT; 27721da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27731da177e4SLinus Torvalds return -EBUSY; 27741da177e4SLinus Torvalds return 0; 27751da177e4SLinus Torvalds } 27761da177e4SLinus Torvalds 27771da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27781da177e4SLinus Torvalds * dir. 27791da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27801da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27811da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2782036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2783036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2784036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27851da177e4SLinus Torvalds */ 2786a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27871da177e4SLinus Torvalds { 2788036d5236SEric W. Biederman struct user_namespace *s_user_ns; 278914e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27901da177e4SLinus Torvalds if (child->d_inode) 27911da177e4SLinus Torvalds return -EEXIST; 27921da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27931da177e4SLinus Torvalds return -ENOENT; 2794036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2795036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2796036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2797036d5236SEric W. Biederman return -EOVERFLOW; 2798*47291baaSChristian Brauner return inode_permission(&init_user_ns, dir, MAY_WRITE | MAY_EXEC); 27991da177e4SLinus Torvalds } 28001da177e4SLinus Torvalds 28011da177e4SLinus Torvalds /* 28021da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28031da177e4SLinus Torvalds */ 28041da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28051da177e4SLinus Torvalds { 28061da177e4SLinus Torvalds struct dentry *p; 28071da177e4SLinus Torvalds 28081da177e4SLinus Torvalds if (p1 == p2) { 28095955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28101da177e4SLinus Torvalds return NULL; 28111da177e4SLinus Torvalds } 28121da177e4SLinus Torvalds 2813fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28141da177e4SLinus Torvalds 2815e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2816e2761a11SOGAWA Hirofumi if (p) { 28175955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28185955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28191da177e4SLinus Torvalds return p; 28201da177e4SLinus Torvalds } 28211da177e4SLinus Torvalds 2822e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2823e2761a11SOGAWA Hirofumi if (p) { 28245955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28255955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28261da177e4SLinus Torvalds return p; 28271da177e4SLinus Torvalds } 28281da177e4SLinus Torvalds 28295955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28305955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28311da177e4SLinus Torvalds return NULL; 28321da177e4SLinus Torvalds } 28334d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28341da177e4SLinus Torvalds 28351da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28361da177e4SLinus Torvalds { 28375955102cSAl Viro inode_unlock(p1->d_inode); 28381da177e4SLinus Torvalds if (p1 != p2) { 28395955102cSAl Viro inode_unlock(p2->d_inode); 2840fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28411da177e4SLinus Torvalds } 28421da177e4SLinus Torvalds } 28434d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28441da177e4SLinus Torvalds 28454acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2846312b63fbSAl Viro bool want_excl) 28471da177e4SLinus Torvalds { 2848a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28491da177e4SLinus Torvalds if (error) 28501da177e4SLinus Torvalds return error; 28511da177e4SLinus Torvalds 2852acfa4380SAl Viro if (!dir->i_op->create) 28531da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28541da177e4SLinus Torvalds mode &= S_IALLUGO; 28551da177e4SLinus Torvalds mode |= S_IFREG; 28561da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28571da177e4SLinus Torvalds if (error) 28581da177e4SLinus Torvalds return error; 2859312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2860a74574aaSStephen Smalley if (!error) 2861f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28621da177e4SLinus Torvalds return error; 28631da177e4SLinus Torvalds } 28644d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28651da177e4SLinus Torvalds 28668e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28678e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28688e6c848eSAl Viro void *arg) 28698e6c848eSAl Viro { 28708e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28718e6c848eSAl Viro int error = may_create(dir, dentry); 28728e6c848eSAl Viro if (error) 28738e6c848eSAl Viro return error; 28748e6c848eSAl Viro 28758e6c848eSAl Viro mode &= S_IALLUGO; 28768e6c848eSAl Viro mode |= S_IFREG; 28778e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28788e6c848eSAl Viro if (error) 28798e6c848eSAl Viro return error; 28808e6c848eSAl Viro error = f(dentry, mode, arg); 28818e6c848eSAl Viro if (!error) 28828e6c848eSAl Viro fsnotify_create(dir, dentry); 28838e6c848eSAl Viro return error; 28848e6c848eSAl Viro } 28858e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28868e6c848eSAl Viro 2887a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2888a2982cc9SEric W. Biederman { 2889a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2890a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2891a2982cc9SEric W. Biederman } 2892a2982cc9SEric W. Biederman 2893f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28941da177e4SLinus Torvalds { 28953fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28961da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28971da177e4SLinus Torvalds int error; 28981da177e4SLinus Torvalds 28991da177e4SLinus Torvalds if (!inode) 29001da177e4SLinus Torvalds return -ENOENT; 29011da177e4SLinus Torvalds 2902c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2903c8fe8f30SChristoph Hellwig case S_IFLNK: 29041da177e4SLinus Torvalds return -ELOOP; 2905c8fe8f30SChristoph Hellwig case S_IFDIR: 2906fc4177beSKees Cook if (acc_mode & MAY_WRITE) 29071da177e4SLinus Torvalds return -EISDIR; 2908fc4177beSKees Cook if (acc_mode & MAY_EXEC) 2909fc4177beSKees Cook return -EACCES; 2910c8fe8f30SChristoph Hellwig break; 2911c8fe8f30SChristoph Hellwig case S_IFBLK: 2912c8fe8f30SChristoph Hellwig case S_IFCHR: 2913a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29141da177e4SLinus Torvalds return -EACCES; 2915633fb6acSKees Cook fallthrough; 2916c8fe8f30SChristoph Hellwig case S_IFIFO: 2917c8fe8f30SChristoph Hellwig case S_IFSOCK: 2918633fb6acSKees Cook if (acc_mode & MAY_EXEC) 2919633fb6acSKees Cook return -EACCES; 29201da177e4SLinus Torvalds flag &= ~O_TRUNC; 2921c8fe8f30SChristoph Hellwig break; 29220fd338b2SKees Cook case S_IFREG: 29230fd338b2SKees Cook if ((acc_mode & MAY_EXEC) && path_noexec(path)) 29240fd338b2SKees Cook return -EACCES; 29250fd338b2SKees Cook break; 29264a3fd211SDave Hansen } 2927b41572e9SDave Hansen 2928*47291baaSChristian Brauner error = inode_permission(&init_user_ns, inode, MAY_OPEN | acc_mode); 2929b41572e9SDave Hansen if (error) 2930b41572e9SDave Hansen return error; 29316146f0d5SMimi Zohar 29321da177e4SLinus Torvalds /* 29331da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29341da177e4SLinus Torvalds */ 29351da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29368737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29377715b521SAl Viro return -EPERM; 29381da177e4SLinus Torvalds if (flag & O_TRUNC) 29397715b521SAl Viro return -EPERM; 29401da177e4SLinus Torvalds } 29411da177e4SLinus Torvalds 29421da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29432e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29447715b521SAl Viro return -EPERM; 29451da177e4SLinus Torvalds 2946f3c7691eSJ. Bruce Fields return 0; 29477715b521SAl Viro } 29487715b521SAl Viro 2949e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29507715b521SAl Viro { 2951f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29527715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29537715b521SAl Viro int error = get_write_access(inode); 29541da177e4SLinus Torvalds if (error) 29557715b521SAl Viro return error; 29561da177e4SLinus Torvalds /* 29571da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29581da177e4SLinus Torvalds */ 2959d7a06983SJeff Layton error = locks_verify_locked(filp); 2960be6d3e56SKentaro Takeda if (!error) 2961ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29621da177e4SLinus Torvalds if (!error) { 29637715b521SAl Viro error = do_truncate(path->dentry, 0, 2964d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2965e1181ee6SJeff Layton filp); 29661da177e4SLinus Torvalds } 29671da177e4SLinus Torvalds put_write_access(inode); 2968acd0c935SMimi Zohar return error; 29691da177e4SLinus Torvalds } 29701da177e4SLinus Torvalds 2971d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2972d57999e1SDave Hansen { 29738a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29748a5e929dSAl Viro flag--; 2975d57999e1SDave Hansen return flag; 2976d57999e1SDave Hansen } 2977d57999e1SDave Hansen 2978d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2979d18e9008SMiklos Szeredi { 29801328c727SSeth Forshee struct user_namespace *s_user_ns; 2981d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2982d18e9008SMiklos Szeredi if (error) 2983d18e9008SMiklos Szeredi return error; 2984d18e9008SMiklos Szeredi 29851328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29861328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29871328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29881328c727SSeth Forshee return -EOVERFLOW; 29891328c727SSeth Forshee 2990*47291baaSChristian Brauner error = inode_permission(&init_user_ns, dir->dentry->d_inode, 2991*47291baaSChristian Brauner MAY_WRITE | MAY_EXEC); 2992d18e9008SMiklos Szeredi if (error) 2993d18e9008SMiklos Szeredi return error; 2994d18e9008SMiklos Szeredi 2995d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2996d18e9008SMiklos Szeredi } 2997d18e9008SMiklos Szeredi 29981acf0af9SDavid Howells /* 29991acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 30001acf0af9SDavid Howells * dentry. 30011acf0af9SDavid Howells * 30021acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 30031acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 30041acf0af9SDavid Howells * 300500a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 300600a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 300700a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 30081acf0af9SDavid Howells * 30091acf0af9SDavid Howells * Returns an error code otherwise. 30101acf0af9SDavid Howells */ 3011239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 3012239eb983SAl Viro struct file *file, 30133ec2eef1SAl Viro int open_flag, umode_t mode) 3014d18e9008SMiklos Szeredi { 3015d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3016d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3017d18e9008SMiklos Szeredi int error; 3018d18e9008SMiklos Szeredi 3019d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3020d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3021d18e9008SMiklos Szeredi 302230d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 302330d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30240fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 302544907d79SAl Viro open_to_namei_flags(open_flag), mode); 30266fbd0714SAl Viro d_lookup_done(dentry); 3027384f26e2SAl Viro if (!error) { 302864e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 30296fb968cdSAl Viro if (unlikely(dentry != file->f_path.dentry)) { 30306fb968cdSAl Viro dput(dentry); 30316fb968cdSAl Viro dentry = dget(file->f_path.dentry); 30326fb968cdSAl Viro } 303364e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 30342675a4ebSAl Viro error = -EIO; 3035384f26e2SAl Viro } else { 303630d90494SAl Viro if (file->f_path.dentry) { 3037d18e9008SMiklos Szeredi dput(dentry); 3038d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 303910c64ceaSAl Viro } 3040239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 3041a01e718fSAl Viro error = -ENOENT; 3042d18e9008SMiklos Szeredi } 3043d18e9008SMiklos Szeredi } 3044239eb983SAl Viro if (error) { 3045d18e9008SMiklos Szeredi dput(dentry); 3046239eb983SAl Viro dentry = ERR_PTR(error); 3047239eb983SAl Viro } 3048239eb983SAl Viro return dentry; 3049d18e9008SMiklos Szeredi } 3050d18e9008SMiklos Szeredi 305131e6b01fSNick Piggin /* 30521acf0af9SDavid Howells * Look up and maybe create and open the last component. 3053d58ffd35SMiklos Szeredi * 305400a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3055d58ffd35SMiklos Szeredi * 305600a07c15SAl Viro * Returns 0 on success, that is, if 305700a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 305800a07c15SAl Viro * the file was not completely opened at this time, though lookups and 305900a07c15SAl Viro * creations were performed. 306000a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 306100a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 306200a07c15SAl Viro * hadn't been specified. 30631acf0af9SDavid Howells * 306400a07c15SAl Viro * An error code is returned on failure. 3065d58ffd35SMiklos Szeredi */ 3066da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 3067d58ffd35SMiklos Szeredi const struct open_flags *op, 30683ec2eef1SAl Viro bool got_write) 3069d58ffd35SMiklos Szeredi { 3070d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 307154ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30721643b43fSAl Viro int open_flag = op->open_flag; 3073d58ffd35SMiklos Szeredi struct dentry *dentry; 30741643b43fSAl Viro int error, create_error = 0; 30751643b43fSAl Viro umode_t mode = op->mode; 30766fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3077d58ffd35SMiklos Szeredi 3078ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3079da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 3080d58ffd35SMiklos Szeredi 308173a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 30826fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30836fbd0714SAl Viro for (;;) { 30846fbd0714SAl Viro if (!dentry) { 30856fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3086d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 3087da5ebf5aSAl Viro return dentry; 30886fbd0714SAl Viro } 30896fbd0714SAl Viro if (d_in_lookup(dentry)) 30906fbd0714SAl Viro break; 3091d58ffd35SMiklos Szeredi 30926fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30936fbd0714SAl Viro if (likely(error > 0)) 30946fbd0714SAl Viro break; 30956fbd0714SAl Viro if (error) 30966fbd0714SAl Viro goto out_dput; 30976fbd0714SAl Viro d_invalidate(dentry); 30986fbd0714SAl Viro dput(dentry); 30996fbd0714SAl Viro dentry = NULL; 31006fbd0714SAl Viro } 31016fbd0714SAl Viro if (dentry->d_inode) { 3102d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3103da5ebf5aSAl Viro return dentry; 31046c51e513SAl Viro } 3105d18e9008SMiklos Szeredi 31061643b43fSAl Viro /* 31071643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31081643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31091643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31101643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31111643b43fSAl Viro * 31121643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31131643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31141643b43fSAl Viro */ 311599a4a90cSAl Viro if (unlikely(!got_write)) 311699a4a90cSAl Viro open_flag &= ~O_TRUNC; 31171643b43fSAl Viro if (open_flag & O_CREAT) { 311899a4a90cSAl Viro if (open_flag & O_EXCL) 311999a4a90cSAl Viro open_flag &= ~O_TRUNC; 31201643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31211643b43fSAl Viro mode &= ~current_umask(); 312299a4a90cSAl Viro if (likely(got_write)) 31231643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 312499a4a90cSAl Viro else 312599a4a90cSAl Viro create_error = -EROFS; 312699a4a90cSAl Viro } 312799a4a90cSAl Viro if (create_error) 31281643b43fSAl Viro open_flag &= ~O_CREAT; 31291643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3130d489cf9aSAl Viro dentry = atomic_open(nd, dentry, file, open_flag, mode); 3131da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3132da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3133da5ebf5aSAl Viro return dentry; 3134239eb983SAl Viro } 313554ef4872SMiklos Szeredi 31366fbd0714SAl Viro if (d_in_lookup(dentry)) { 313712fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 313812fa5e24SAl Viro nd->flags); 31396fbd0714SAl Viro d_lookup_done(dentry); 314012fa5e24SAl Viro if (unlikely(res)) { 314112fa5e24SAl Viro if (IS_ERR(res)) { 314212fa5e24SAl Viro error = PTR_ERR(res); 314312fa5e24SAl Viro goto out_dput; 314412fa5e24SAl Viro } 314512fa5e24SAl Viro dput(dentry); 314612fa5e24SAl Viro dentry = res; 314712fa5e24SAl Viro } 314854ef4872SMiklos Szeredi } 314954ef4872SMiklos Szeredi 3150d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31511643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 315273a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3153ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3154ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3155ce8644fcSAl Viro error = -EACCES; 3156d58ffd35SMiklos Szeredi goto out_dput; 315764894cf8SAl Viro } 3158ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31591643b43fSAl Viro open_flag & O_EXCL); 3160d58ffd35SMiklos Szeredi if (error) 3161d58ffd35SMiklos Szeredi goto out_dput; 3162d58ffd35SMiklos Szeredi } 31631643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31641643b43fSAl Viro error = create_error; 3165d58ffd35SMiklos Szeredi goto out_dput; 3166d58ffd35SMiklos Szeredi } 3167da5ebf5aSAl Viro return dentry; 3168d58ffd35SMiklos Szeredi 3169d58ffd35SMiklos Szeredi out_dput: 3170d58ffd35SMiklos Szeredi dput(dentry); 3171da5ebf5aSAl Viro return ERR_PTR(error); 3172d58ffd35SMiklos Szeredi } 3173d58ffd35SMiklos Szeredi 3174c981a482SAl Viro static const char *open_last_lookups(struct nameidata *nd, 31753ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3176fb1cc555SAl Viro { 3177a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3178ca344a89SAl Viro int open_flag = op->open_flag; 317964894cf8SAl Viro bool got_write = false; 3180254cf582SAl Viro unsigned seq; 3181a1eb3315SMiklos Szeredi struct inode *inode; 3182da5ebf5aSAl Viro struct dentry *dentry; 3183b0417d2cSAl Viro const char *res; 318416c2cd71SAl Viro int error; 3185fb1cc555SAl Viro 3186c3e380b0SAl Viro nd->flags |= op->intent; 3187c3e380b0SAl Viro 3188bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 318956676ec3SAl Viro if (nd->depth) 319056676ec3SAl Viro put_link(nd); 3191ff326a32SAl Viro return handle_dots(nd, nd->last_type); 31921f36f774SAl Viro } 3193a2c36b45SAl Viro 3194ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3195fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3196fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3197fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 319820e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 319920e34357SAl Viro if (IS_ERR(dentry)) 32001ccac622SAl Viro return ERR_CAST(dentry); 320120e34357SAl Viro if (likely(dentry)) 320271574865SMiklos Szeredi goto finish_lookup; 320371574865SMiklos Szeredi 32046583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3205b6183df7SMiklos Szeredi } else { 3206fe2d35ffSAl Viro /* create side of things */ 320772287417SAl Viro if (nd->flags & LOOKUP_RCU) { 320872287417SAl Viro error = unlazy_walk(nd); 3209c981a482SAl Viro if (unlikely(error)) 32101ccac622SAl Viro return ERR_PTR(error); 321172287417SAl Viro } 3212c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 32131f36f774SAl Viro /* trailing slashes? */ 3214deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 32151ccac622SAl Viro return ERR_PTR(-EISDIR); 3216b6183df7SMiklos Szeredi } 32171f36f774SAl Viro 32189cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 321964894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 322064894cf8SAl Viro if (!error) 322164894cf8SAl Viro got_write = true; 322264894cf8SAl Viro /* 322364894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 322464894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 322564894cf8SAl Viro * dropping this one anyway. 322664894cf8SAl Viro */ 322764894cf8SAl Viro } 32289cf843e3SAl Viro if (open_flag & O_CREAT) 32295955102cSAl Viro inode_lock(dir->d_inode); 32309cf843e3SAl Viro else 32319cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3232da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 3233f7bb959dSAl Viro if (!IS_ERR(dentry) && (file->f_mode & FMODE_CREATED)) 3234f7bb959dSAl Viro fsnotify_create(dir->d_inode, dentry); 32359cf843e3SAl Viro if (open_flag & O_CREAT) 32365955102cSAl Viro inode_unlock(dir->d_inode); 32379cf843e3SAl Viro else 32389cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3239fb1cc555SAl Viro 3240c981a482SAl Viro if (got_write) 324159e96e65SAl Viro mnt_drop_write(nd->path.mnt); 32426c0d46c4SAl Viro 324359e96e65SAl Viro if (IS_ERR(dentry)) 324459e96e65SAl Viro return ERR_CAST(dentry); 324559e96e65SAl Viro 3246973d4b73SAl Viro if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) { 3247e73cabffSAl Viro dput(nd->path.dentry); 3248e73cabffSAl Viro nd->path.dentry = dentry; 3249c981a482SAl Viro return NULL; 3250fb1cc555SAl Viro } 3251fb1cc555SAl Viro 325220e34357SAl Viro finish_lookup: 325356676ec3SAl Viro if (nd->depth) 325456676ec3SAl Viro put_link(nd); 32558c4efe22SAl Viro res = step_into(nd, WALK_TRAILING, dentry, inode, seq); 3256ff326a32SAl Viro if (unlikely(res)) 32571ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3258b0417d2cSAl Viro return res; 32591ccac622SAl Viro } 326031d1726dSAl Viro 3261c981a482SAl Viro /* 3262c981a482SAl Viro * Handle the last step of open() 3263c981a482SAl Viro */ 3264c5971b8cSAl Viro static int do_open(struct nameidata *nd, 3265c981a482SAl Viro struct file *file, const struct open_flags *op) 3266c981a482SAl Viro { 3267c981a482SAl Viro int open_flag = op->open_flag; 3268c981a482SAl Viro bool do_truncate; 3269c981a482SAl Viro int acc_mode; 3270c981a482SAl Viro int error; 3271c981a482SAl Viro 3272ff326a32SAl Viro if (!(file->f_mode & (FMODE_OPENED | FMODE_CREATED))) { 3273ff326a32SAl Viro error = complete_walk(nd); 3274ff326a32SAl Viro if (error) 3275ff326a32SAl Viro return error; 3276ff326a32SAl Viro } 3277973d4b73SAl Viro if (!(file->f_mode & FMODE_CREATED)) 327876ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 327930aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3280b94e0b32SAl Viro if ((open_flag & O_EXCL) && !(file->f_mode & FMODE_CREATED)) 3281b94e0b32SAl Viro return -EEXIST; 328230aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 3283c5971b8cSAl Viro return -EISDIR; 32840f705953SAl Viro error = may_create_in_sticky(nd->dir_mode, nd->dir_uid, 328530aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 328630aba665SSalvatore Mesoraca if (unlikely(error)) 3287c5971b8cSAl Viro return error; 328830aba665SSalvatore Mesoraca } 328944b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 3290c5971b8cSAl Viro return -ENOTDIR; 32916c0d46c4SAl Viro 32928795e7d4SAl Viro do_truncate = false; 32938795e7d4SAl Viro acc_mode = op->acc_mode; 32945a2d3eddSAl Viro if (file->f_mode & FMODE_CREATED) { 32955a2d3eddSAl Viro /* Don't check for write permission, don't truncate */ 32965a2d3eddSAl Viro open_flag &= ~O_TRUNC; 32975a2d3eddSAl Viro acc_mode = 0; 32988795e7d4SAl Viro } else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) { 32990f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33000f9d1a10SAl Viro if (error) 3301c5971b8cSAl Viro return error; 33028795e7d4SAl Viro do_truncate = true; 33030f9d1a10SAl Viro } 3304bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 33058795e7d4SAl Viro if (!error && !(file->f_mode & FMODE_OPENED)) 3306ae2bb293SAl Viro error = vfs_open(&nd->path, file); 33078795e7d4SAl Viro if (!error) 33086035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 33098795e7d4SAl Viro if (!error && do_truncate) 33102675a4ebSAl Viro error = handle_truncate(file); 3311c80567c8SAl Viro if (unlikely(error > 0)) { 3312c80567c8SAl Viro WARN_ON(1); 3313c80567c8SAl Viro error = -EINVAL; 3314c80567c8SAl Viro } 33158795e7d4SAl Viro if (do_truncate) 33160f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 3317c5971b8cSAl Viro return error; 3318fb1cc555SAl Viro } 3319fb1cc555SAl Viro 3320af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3321af7bd4dcSAmir Goldstein { 3322af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3323af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3324af7bd4dcSAmir Goldstein struct inode *inode; 3325af7bd4dcSAmir Goldstein int error; 3326af7bd4dcSAmir Goldstein 3327af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3328*47291baaSChristian Brauner error = inode_permission(&init_user_ns, dir, MAY_WRITE | MAY_EXEC); 3329af7bd4dcSAmir Goldstein if (error) 3330af7bd4dcSAmir Goldstein goto out_err; 3331af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3332af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3333af7bd4dcSAmir Goldstein goto out_err; 3334af7bd4dcSAmir Goldstein error = -ENOMEM; 3335cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3336af7bd4dcSAmir Goldstein if (unlikely(!child)) 3337af7bd4dcSAmir Goldstein goto out_err; 3338af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3339af7bd4dcSAmir Goldstein if (error) 3340af7bd4dcSAmir Goldstein goto out_err; 3341af7bd4dcSAmir Goldstein error = -ENOENT; 3342af7bd4dcSAmir Goldstein inode = child->d_inode; 3343af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3344af7bd4dcSAmir Goldstein goto out_err; 3345af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3346af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3347af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3348af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3349af7bd4dcSAmir Goldstein } 3350fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3351af7bd4dcSAmir Goldstein return child; 3352af7bd4dcSAmir Goldstein 3353af7bd4dcSAmir Goldstein out_err: 3354af7bd4dcSAmir Goldstein dput(child); 3355af7bd4dcSAmir Goldstein return ERR_PTR(error); 3356af7bd4dcSAmir Goldstein } 3357af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3358af7bd4dcSAmir Goldstein 3359c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 336060545d0dSAl Viro const struct open_flags *op, 33613ec2eef1SAl Viro struct file *file) 336260545d0dSAl Viro { 3363625b6d10SAl Viro struct dentry *child; 3364625b6d10SAl Viro struct path path; 3365c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 336660545d0dSAl Viro if (unlikely(error)) 336760545d0dSAl Viro return error; 3368625b6d10SAl Viro error = mnt_want_write(path.mnt); 336960545d0dSAl Viro if (unlikely(error)) 337060545d0dSAl Viro goto out; 3371af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3372af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3373684e73beSHirofumi Nakagawa if (IS_ERR(child)) 337460545d0dSAl Viro goto out2; 3375625b6d10SAl Viro dput(path.dentry); 3376625b6d10SAl Viro path.dentry = child; 3377c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 337869a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 337962fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 338060545d0dSAl Viro if (error) 338160545d0dSAl Viro goto out2; 3382625b6d10SAl Viro file->f_path.mnt = path.mnt; 3383be12af3eSAl Viro error = finish_open(file, child, NULL); 338460545d0dSAl Viro out2: 3385625b6d10SAl Viro mnt_drop_write(path.mnt); 338660545d0dSAl Viro out: 3387625b6d10SAl Viro path_put(&path); 338860545d0dSAl Viro return error; 338960545d0dSAl Viro } 339060545d0dSAl Viro 33916ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 33926ac08709SAl Viro { 33936ac08709SAl Viro struct path path; 33946ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 33956ac08709SAl Viro if (!error) { 33966ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3397ae2bb293SAl Viro error = vfs_open(&path, file); 33986ac08709SAl Viro path_put(&path); 33996ac08709SAl Viro } 34006ac08709SAl Viro return error; 34016ac08709SAl Viro } 34026ac08709SAl Viro 3403c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3404c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34051da177e4SLinus Torvalds { 340630d90494SAl Viro struct file *file; 340713aab428SAl Viro int error; 340831e6b01fSNick Piggin 3409ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 34101afc99beSAl Viro if (IS_ERR(file)) 34111afc99beSAl Viro return file; 341231e6b01fSNick Piggin 3413bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 34143ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 34155f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 34166ac08709SAl Viro error = do_o_path(nd, flags, file); 34175f336e72SAl Viro } else { 34185f336e72SAl Viro const char *s = path_init(nd, flags); 34193bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 3420c5971b8cSAl Viro (s = open_last_lookups(nd, file, op)) != NULL) 34211ccac622SAl Viro ; 3422c5971b8cSAl Viro if (!error) 3423c5971b8cSAl Viro error = do_open(nd, file, op); 3424deb106c6SAl Viro terminate_walk(nd); 34255f336e72SAl Viro } 34267c1c01ecSAl Viro if (likely(!error)) { 3427aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 34287c1c01ecSAl Viro return file; 34297c1c01ecSAl Viro WARN_ON(1); 34307c1c01ecSAl Viro error = -EINVAL; 3431015c3bbcSMiklos Szeredi } 34327c1c01ecSAl Viro fput(file); 34332675a4ebSAl Viro if (error == -EOPENSTALE) { 34342675a4ebSAl Viro if (flags & LOOKUP_RCU) 34352675a4ebSAl Viro error = -ECHILD; 34362675a4ebSAl Viro else 34372675a4ebSAl Viro error = -ESTALE; 34382675a4ebSAl Viro } 34397c1c01ecSAl Viro return ERR_PTR(error); 3440de459215SKirill Korotaev } 34411da177e4SLinus Torvalds 3442669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3443f9652e10SAl Viro const struct open_flags *op) 344413aab428SAl Viro { 34459883d185SAl Viro struct nameidata nd; 3446f9652e10SAl Viro int flags = op->lookup_flags; 344713aab428SAl Viro struct file *filp; 344813aab428SAl Viro 34499883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3450c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 345113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3452c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 345313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3454c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34559883d185SAl Viro restore_nameidata(); 345613aab428SAl Viro return filp; 345713aab428SAl Viro } 345813aab428SAl Viro 345973d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3460f9652e10SAl Viro const char *name, const struct open_flags *op) 346173d049a4SAl Viro { 34629883d185SAl Viro struct nameidata nd; 346373d049a4SAl Viro struct file *file; 346451689104SPaul Moore struct filename *filename; 3465f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 346673d049a4SAl Viro 346773d049a4SAl Viro nd.root.mnt = mnt; 346873d049a4SAl Viro nd.root.dentry = dentry; 346973d049a4SAl Viro 3470b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 347173d049a4SAl Viro return ERR_PTR(-ELOOP); 347273d049a4SAl Viro 347351689104SPaul Moore filename = getname_kernel(name); 3474a1c83681SViresh Kumar if (IS_ERR(filename)) 347551689104SPaul Moore return ERR_CAST(filename); 347651689104SPaul Moore 34779883d185SAl Viro set_nameidata(&nd, -1, filename); 3478c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 347973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3480c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 348173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3482c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 34839883d185SAl Viro restore_nameidata(); 348451689104SPaul Moore putname(filename); 348573d049a4SAl Viro return file; 348673d049a4SAl Viro } 348773d049a4SAl Viro 3488fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34891ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34901da177e4SLinus Torvalds { 3491c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3492391172c4SAl Viro struct qstr last; 3493391172c4SAl Viro int type; 3494c30dabfeSJan Kara int err2; 34951ac12b4bSJeff Layton int error; 34961ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34971ac12b4bSJeff Layton 34981ac12b4bSJeff Layton /* 34991ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35001ac12b4bSJeff Layton * other flags passed in are ignored! 35011ac12b4bSJeff Layton */ 35021ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35031ac12b4bSJeff Layton 35045c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35055c31b6ceSAl Viro if (IS_ERR(name)) 35065c31b6ceSAl Viro return ERR_CAST(name); 35071da177e4SLinus Torvalds 3508c663e5d8SChristoph Hellwig /* 3509c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3510c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3511c663e5d8SChristoph Hellwig */ 35125c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3513ed75e95dSAl Viro goto out; 3514c663e5d8SChristoph Hellwig 3515c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3516391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3517c663e5d8SChristoph Hellwig /* 3518c663e5d8SChristoph Hellwig * Do the final lookup. 3519c663e5d8SChristoph Hellwig */ 3520391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 35215955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3522391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 35231da177e4SLinus Torvalds if (IS_ERR(dentry)) 3524a8104a9fSAl Viro goto unlock; 3525c663e5d8SChristoph Hellwig 3526a8104a9fSAl Viro error = -EEXIST; 3527b18825a7SDavid Howells if (d_is_positive(dentry)) 3528a8104a9fSAl Viro goto fail; 3529b18825a7SDavid Howells 3530c663e5d8SChristoph Hellwig /* 3531c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3532c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3533c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3534c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3535c663e5d8SChristoph Hellwig */ 3536391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3537a8104a9fSAl Viro error = -ENOENT; 3538ed75e95dSAl Viro goto fail; 3539e9baf6e5SAl Viro } 3540c30dabfeSJan Kara if (unlikely(err2)) { 3541c30dabfeSJan Kara error = err2; 3542a8104a9fSAl Viro goto fail; 3543c30dabfeSJan Kara } 3544181c37b6SAl Viro putname(name); 3545e9baf6e5SAl Viro return dentry; 35461da177e4SLinus Torvalds fail: 3547a8104a9fSAl Viro dput(dentry); 3548a8104a9fSAl Viro dentry = ERR_PTR(error); 3549a8104a9fSAl Viro unlock: 35505955102cSAl Viro inode_unlock(path->dentry->d_inode); 3551c30dabfeSJan Kara if (!err2) 3552391172c4SAl Viro mnt_drop_write(path->mnt); 3553ed75e95dSAl Viro out: 3554391172c4SAl Viro path_put(path); 3555181c37b6SAl Viro putname(name); 3556ed75e95dSAl Viro return dentry; 3557dae6ad8fSAl Viro } 3558fa14a0b8SAl Viro 3559fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3560fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3561fa14a0b8SAl Viro { 3562181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3563181c37b6SAl Viro path, lookup_flags); 3564fa14a0b8SAl Viro } 3565dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3566dae6ad8fSAl Viro 3567921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3568921a1650SAl Viro { 3569921a1650SAl Viro dput(dentry); 35705955102cSAl Viro inode_unlock(path->dentry->d_inode); 3571a8104a9fSAl Viro mnt_drop_write(path->mnt); 3572921a1650SAl Viro path_put(path); 3573921a1650SAl Viro } 3574921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3575921a1650SAl Viro 3576520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35771ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3578dae6ad8fSAl Viro { 3579181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3580dae6ad8fSAl Viro } 3581dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3582dae6ad8fSAl Viro 35831a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35841da177e4SLinus Torvalds { 3585a3c751a5SMiklos Szeredi bool is_whiteout = S_ISCHR(mode) && dev == WHITEOUT_DEV; 3586a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35871da177e4SLinus Torvalds 35881da177e4SLinus Torvalds if (error) 35891da177e4SLinus Torvalds return error; 35901da177e4SLinus Torvalds 3591a3c751a5SMiklos Szeredi if ((S_ISCHR(mode) || S_ISBLK(mode)) && !is_whiteout && 3592a3c751a5SMiklos Szeredi !capable(CAP_MKNOD)) 35931da177e4SLinus Torvalds return -EPERM; 35941da177e4SLinus Torvalds 3595acfa4380SAl Viro if (!dir->i_op->mknod) 35961da177e4SLinus Torvalds return -EPERM; 35971da177e4SLinus Torvalds 359808ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 359908ce5f16SSerge E. Hallyn if (error) 360008ce5f16SSerge E. Hallyn return error; 360108ce5f16SSerge E. Hallyn 36021da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36031da177e4SLinus Torvalds if (error) 36041da177e4SLinus Torvalds return error; 36051da177e4SLinus Torvalds 36061da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3607a74574aaSStephen Smalley if (!error) 3608f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36091da177e4SLinus Torvalds return error; 36101da177e4SLinus Torvalds } 36114d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36121da177e4SLinus Torvalds 3613f69aac00SAl Viro static int may_mknod(umode_t mode) 3614463c3197SDave Hansen { 3615463c3197SDave Hansen switch (mode & S_IFMT) { 3616463c3197SDave Hansen case S_IFREG: 3617463c3197SDave Hansen case S_IFCHR: 3618463c3197SDave Hansen case S_IFBLK: 3619463c3197SDave Hansen case S_IFIFO: 3620463c3197SDave Hansen case S_IFSOCK: 3621463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3622463c3197SDave Hansen return 0; 3623463c3197SDave Hansen case S_IFDIR: 3624463c3197SDave Hansen return -EPERM; 3625463c3197SDave Hansen default: 3626463c3197SDave Hansen return -EINVAL; 3627463c3197SDave Hansen } 3628463c3197SDave Hansen } 3629463c3197SDave Hansen 36305fee64fcSChristoph Hellwig static long do_mknodat(int dfd, const char __user *filename, umode_t mode, 363187c4e192SDominik Brodowski unsigned int dev) 36321da177e4SLinus Torvalds { 36331da177e4SLinus Torvalds struct dentry *dentry; 3634dae6ad8fSAl Viro struct path path; 3635dae6ad8fSAl Viro int error; 3636972567f1SJeff Layton unsigned int lookup_flags = 0; 36371da177e4SLinus Torvalds 36388e4bfca1SAl Viro error = may_mknod(mode); 36398e4bfca1SAl Viro if (error) 36408e4bfca1SAl Viro return error; 3641972567f1SJeff Layton retry: 3642972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3643dae6ad8fSAl Viro if (IS_ERR(dentry)) 3644dae6ad8fSAl Viro return PTR_ERR(dentry); 36452ad94ae6SAl Viro 3646dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3647ce3b0f8dSAl Viro mode &= ~current_umask(); 3648dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3649be6d3e56SKentaro Takeda if (error) 3650a8104a9fSAl Viro goto out; 36511da177e4SLinus Torvalds switch (mode & S_IFMT) { 36521da177e4SLinus Torvalds case 0: case S_IFREG: 3653312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 365405d1a717SMimi Zohar if (!error) 365505d1a717SMimi Zohar ima_post_path_mknod(dentry); 36561da177e4SLinus Torvalds break; 36571da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3658dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36591da177e4SLinus Torvalds new_decode_dev(dev)); 36601da177e4SLinus Torvalds break; 36611da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3662dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36631da177e4SLinus Torvalds break; 36641da177e4SLinus Torvalds } 3665a8104a9fSAl Viro out: 3666921a1650SAl Viro done_path_create(&path, dentry); 3667972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3668972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3669972567f1SJeff Layton goto retry; 3670972567f1SJeff Layton } 36711da177e4SLinus Torvalds return error; 36721da177e4SLinus Torvalds } 36731da177e4SLinus Torvalds 367487c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 367587c4e192SDominik Brodowski unsigned int, dev) 367687c4e192SDominik Brodowski { 367787c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 367887c4e192SDominik Brodowski } 367987c4e192SDominik Brodowski 36808208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36815590ff0dSUlrich Drepper { 368287c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 36835590ff0dSUlrich Drepper } 36845590ff0dSUlrich Drepper 368518bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36861da177e4SLinus Torvalds { 3687a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36888de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36891da177e4SLinus Torvalds 36901da177e4SLinus Torvalds if (error) 36911da177e4SLinus Torvalds return error; 36921da177e4SLinus Torvalds 3693acfa4380SAl Viro if (!dir->i_op->mkdir) 36941da177e4SLinus Torvalds return -EPERM; 36951da177e4SLinus Torvalds 36961da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36971da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36981da177e4SLinus Torvalds if (error) 36991da177e4SLinus Torvalds return error; 37001da177e4SLinus Torvalds 37018de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37028de52778SAl Viro return -EMLINK; 37038de52778SAl Viro 37041da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3705a74574aaSStephen Smalley if (!error) 3706f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37071da177e4SLinus Torvalds return error; 37081da177e4SLinus Torvalds } 37094d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37101da177e4SLinus Torvalds 371183ff98c3SChristoph Hellwig static long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 37121da177e4SLinus Torvalds { 37136902d925SDave Hansen struct dentry *dentry; 3714dae6ad8fSAl Viro struct path path; 3715dae6ad8fSAl Viro int error; 3716b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37171da177e4SLinus Torvalds 3718b76d8b82SJeff Layton retry: 3719b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37206902d925SDave Hansen if (IS_ERR(dentry)) 3721dae6ad8fSAl Viro return PTR_ERR(dentry); 37226902d925SDave Hansen 3723dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3724ce3b0f8dSAl Viro mode &= ~current_umask(); 3725dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3726a8104a9fSAl Viro if (!error) 3727dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3728921a1650SAl Viro done_path_create(&path, dentry); 3729b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3730b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3731b76d8b82SJeff Layton goto retry; 3732b76d8b82SJeff Layton } 37331da177e4SLinus Torvalds return error; 37341da177e4SLinus Torvalds } 37351da177e4SLinus Torvalds 37360101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37370101db7aSDominik Brodowski { 37380101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 37390101db7aSDominik Brodowski } 37400101db7aSDominik Brodowski 3741a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37425590ff0dSUlrich Drepper { 37430101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 37445590ff0dSUlrich Drepper } 37455590ff0dSUlrich Drepper 37461da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37471da177e4SLinus Torvalds { 37481da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37491da177e4SLinus Torvalds 37501da177e4SLinus Torvalds if (error) 37511da177e4SLinus Torvalds return error; 37521da177e4SLinus Torvalds 3753acfa4380SAl Viro if (!dir->i_op->rmdir) 37541da177e4SLinus Torvalds return -EPERM; 37551da177e4SLinus Torvalds 37561d2ef590SAl Viro dget(dentry); 37575955102cSAl Viro inode_lock(dentry->d_inode); 3758912dbc15SSage Weil 37591da177e4SLinus Torvalds error = -EBUSY; 37607af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3761912dbc15SSage Weil goto out; 3762912dbc15SSage Weil 37631da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3764912dbc15SSage Weil if (error) 3765912dbc15SSage Weil goto out; 3766912dbc15SSage Weil 37671da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3768912dbc15SSage Weil if (error) 3769912dbc15SSage Weil goto out; 3770912dbc15SSage Weil 37718767712fSAl Viro shrink_dcache_parent(dentry); 37721da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3773d83c49f3SAl Viro dont_mount(dentry); 37748ed936b5SEric W. Biederman detach_mounts(dentry); 3775116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 37761da177e4SLinus Torvalds 3777912dbc15SSage Weil out: 37785955102cSAl Viro inode_unlock(dentry->d_inode); 37791d2ef590SAl Viro dput(dentry); 3780912dbc15SSage Weil if (!error) 3781912dbc15SSage Weil d_delete(dentry); 37821da177e4SLinus Torvalds return error; 37831da177e4SLinus Torvalds } 37844d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37851da177e4SLinus Torvalds 3786e24ab0efSChristoph Hellwig long do_rmdir(int dfd, struct filename *name) 37871da177e4SLinus Torvalds { 37881da177e4SLinus Torvalds int error = 0; 37891da177e4SLinus Torvalds struct dentry *dentry; 3790f5beed75SAl Viro struct path path; 3791f5beed75SAl Viro struct qstr last; 3792f5beed75SAl Viro int type; 3793c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3794c6ee9206SJeff Layton retry: 3795e24ab0efSChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, 3796c1d4dd27SAl Viro &path, &last, &type); 379791a27b2aSJeff Layton if (IS_ERR(name)) 379891a27b2aSJeff Layton return PTR_ERR(name); 37991da177e4SLinus Torvalds 3800f5beed75SAl Viro switch (type) { 38011da177e4SLinus Torvalds case LAST_DOTDOT: 38021da177e4SLinus Torvalds error = -ENOTEMPTY; 38031da177e4SLinus Torvalds goto exit1; 38041da177e4SLinus Torvalds case LAST_DOT: 38051da177e4SLinus Torvalds error = -EINVAL; 38061da177e4SLinus Torvalds goto exit1; 38071da177e4SLinus Torvalds case LAST_ROOT: 38081da177e4SLinus Torvalds error = -EBUSY; 38091da177e4SLinus Torvalds goto exit1; 38101da177e4SLinus Torvalds } 38110612d9fbSOGAWA Hirofumi 3812f5beed75SAl Viro error = mnt_want_write(path.mnt); 3813c30dabfeSJan Kara if (error) 3814c30dabfeSJan Kara goto exit1; 38150612d9fbSOGAWA Hirofumi 38165955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3817f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38181da177e4SLinus Torvalds error = PTR_ERR(dentry); 38196902d925SDave Hansen if (IS_ERR(dentry)) 38206902d925SDave Hansen goto exit2; 3821e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3822e6bc45d6STheodore Ts'o error = -ENOENT; 3823e6bc45d6STheodore Ts'o goto exit3; 3824e6bc45d6STheodore Ts'o } 3825f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3826be6d3e56SKentaro Takeda if (error) 3827c30dabfeSJan Kara goto exit3; 3828f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38290622753bSDave Hansen exit3: 38301da177e4SLinus Torvalds dput(dentry); 38316902d925SDave Hansen exit2: 38325955102cSAl Viro inode_unlock(path.dentry->d_inode); 3833f5beed75SAl Viro mnt_drop_write(path.mnt); 38341da177e4SLinus Torvalds exit1: 3835f5beed75SAl Viro path_put(&path); 3836c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3837c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3838c6ee9206SJeff Layton goto retry; 3839c6ee9206SJeff Layton } 384024fb33d4SAl Viro putname(name); 38411da177e4SLinus Torvalds return error; 38421da177e4SLinus Torvalds } 38431da177e4SLinus Torvalds 38443cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38455590ff0dSUlrich Drepper { 3846e24ab0efSChristoph Hellwig return do_rmdir(AT_FDCWD, getname(pathname)); 38475590ff0dSUlrich Drepper } 38485590ff0dSUlrich Drepper 3849b21996e3SJ. Bruce Fields /** 3850b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3851b21996e3SJ. Bruce Fields * @dir: parent directory 3852b21996e3SJ. Bruce Fields * @dentry: victim 3853b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3854b21996e3SJ. Bruce Fields * 3855b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3856b21996e3SJ. Bruce Fields * 3857b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3858b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3859b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3860b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3861b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3862b21996e3SJ. Bruce Fields * 3863b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3864b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3865b21996e3SJ. Bruce Fields * to be NFS exported. 3866b21996e3SJ. Bruce Fields */ 3867b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38681da177e4SLinus Torvalds { 38699accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38701da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38711da177e4SLinus Torvalds 38721da177e4SLinus Torvalds if (error) 38731da177e4SLinus Torvalds return error; 38741da177e4SLinus Torvalds 3875acfa4380SAl Viro if (!dir->i_op->unlink) 38761da177e4SLinus Torvalds return -EPERM; 38771da177e4SLinus Torvalds 38785955102cSAl Viro inode_lock(target); 38798ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38801da177e4SLinus Torvalds error = -EBUSY; 38811da177e4SLinus Torvalds else { 38821da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3883bec1052eSAl Viro if (!error) { 38845a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38855a14696cSJ. Bruce Fields if (error) 3886b21996e3SJ. Bruce Fields goto out; 38871da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38888ed936b5SEric W. Biederman if (!error) { 3889d83c49f3SAl Viro dont_mount(dentry); 38908ed936b5SEric W. Biederman detach_mounts(dentry); 3891116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 38928ed936b5SEric W. Biederman } 3893bec1052eSAl Viro } 38941da177e4SLinus Torvalds } 3895b21996e3SJ. Bruce Fields out: 38965955102cSAl Viro inode_unlock(target); 38971da177e4SLinus Torvalds 38981da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38991da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39009accbb97SJ. Bruce Fields fsnotify_link_count(target); 39011da177e4SLinus Torvalds d_delete(dentry); 39021da177e4SLinus Torvalds } 39030eeca283SRobert Love 39041da177e4SLinus Torvalds return error; 39051da177e4SLinus Torvalds } 39064d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39071da177e4SLinus Torvalds 39081da177e4SLinus Torvalds /* 39091da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39101b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39111da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39121da177e4SLinus Torvalds * while waiting on the I/O. 39131da177e4SLinus Torvalds */ 3914da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 39151da177e4SLinus Torvalds { 39162ad94ae6SAl Viro int error; 39171da177e4SLinus Torvalds struct dentry *dentry; 3918f5beed75SAl Viro struct path path; 3919f5beed75SAl Viro struct qstr last; 3920f5beed75SAl Viro int type; 39211da177e4SLinus Torvalds struct inode *inode = NULL; 3922b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39235d18f813SJeff Layton unsigned int lookup_flags = 0; 39245d18f813SJeff Layton retry: 3925da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 392691a27b2aSJeff Layton if (IS_ERR(name)) 392791a27b2aSJeff Layton return PTR_ERR(name); 39282ad94ae6SAl Viro 39291da177e4SLinus Torvalds error = -EISDIR; 3930f5beed75SAl Viro if (type != LAST_NORM) 39311da177e4SLinus Torvalds goto exit1; 39320612d9fbSOGAWA Hirofumi 3933f5beed75SAl Viro error = mnt_want_write(path.mnt); 3934c30dabfeSJan Kara if (error) 3935c30dabfeSJan Kara goto exit1; 3936b21996e3SJ. Bruce Fields retry_deleg: 39375955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3938f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39391da177e4SLinus Torvalds error = PTR_ERR(dentry); 39401da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39411da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3942f5beed75SAl Viro if (last.name[last.len]) 394350338b88STörök Edwin goto slashes; 39441da177e4SLinus Torvalds inode = dentry->d_inode; 3945b18825a7SDavid Howells if (d_is_negative(dentry)) 3946e6bc45d6STheodore Ts'o goto slashes; 39477de9c6eeSAl Viro ihold(inode); 3948f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3949be6d3e56SKentaro Takeda if (error) 3950c30dabfeSJan Kara goto exit2; 3951f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39521da177e4SLinus Torvalds exit2: 39531da177e4SLinus Torvalds dput(dentry); 39541da177e4SLinus Torvalds } 39555955102cSAl Viro inode_unlock(path.dentry->d_inode); 39561da177e4SLinus Torvalds if (inode) 39571da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3958b21996e3SJ. Bruce Fields inode = NULL; 3959b21996e3SJ. Bruce Fields if (delegated_inode) { 39605a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3961b21996e3SJ. Bruce Fields if (!error) 3962b21996e3SJ. Bruce Fields goto retry_deleg; 3963b21996e3SJ. Bruce Fields } 3964f5beed75SAl Viro mnt_drop_write(path.mnt); 39651da177e4SLinus Torvalds exit1: 3966f5beed75SAl Viro path_put(&path); 39675d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39685d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39695d18f813SJeff Layton inode = NULL; 39705d18f813SJeff Layton goto retry; 39715d18f813SJeff Layton } 3972da2f1362SChristoph Hellwig putname(name); 39731da177e4SLinus Torvalds return error; 39741da177e4SLinus Torvalds 39751da177e4SLinus Torvalds slashes: 3976b18825a7SDavid Howells if (d_is_negative(dentry)) 3977b18825a7SDavid Howells error = -ENOENT; 397844b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3979b18825a7SDavid Howells error = -EISDIR; 3980b18825a7SDavid Howells else 3981b18825a7SDavid Howells error = -ENOTDIR; 39821da177e4SLinus Torvalds goto exit2; 39831da177e4SLinus Torvalds } 39841da177e4SLinus Torvalds 39852e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39865590ff0dSUlrich Drepper { 39875590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39885590ff0dSUlrich Drepper return -EINVAL; 39895590ff0dSUlrich Drepper 39905590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 3991e24ab0efSChristoph Hellwig return do_rmdir(dfd, getname(pathname)); 3992da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 39935590ff0dSUlrich Drepper } 39945590ff0dSUlrich Drepper 39953480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39965590ff0dSUlrich Drepper { 3997da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 39985590ff0dSUlrich Drepper } 39995590ff0dSUlrich Drepper 4000db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40011da177e4SLinus Torvalds { 4002a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40031da177e4SLinus Torvalds 40041da177e4SLinus Torvalds if (error) 40051da177e4SLinus Torvalds return error; 40061da177e4SLinus Torvalds 4007acfa4380SAl Viro if (!dir->i_op->symlink) 40081da177e4SLinus Torvalds return -EPERM; 40091da177e4SLinus Torvalds 40101da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40111da177e4SLinus Torvalds if (error) 40121da177e4SLinus Torvalds return error; 40131da177e4SLinus Torvalds 40141da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4015a74574aaSStephen Smalley if (!error) 4016f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40171da177e4SLinus Torvalds return error; 40181da177e4SLinus Torvalds } 40194d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40201da177e4SLinus Torvalds 4021cd3acb6aSChristoph Hellwig static long do_symlinkat(const char __user *oldname, int newdfd, 4022b724e846SDominik Brodowski const char __user *newname) 40231da177e4SLinus Torvalds { 40242ad94ae6SAl Viro int error; 402591a27b2aSJeff Layton struct filename *from; 40266902d925SDave Hansen struct dentry *dentry; 4027dae6ad8fSAl Viro struct path path; 4028f46d3567SJeff Layton unsigned int lookup_flags = 0; 40291da177e4SLinus Torvalds 40301da177e4SLinus Torvalds from = getname(oldname); 40311da177e4SLinus Torvalds if (IS_ERR(from)) 40321da177e4SLinus Torvalds return PTR_ERR(from); 4033f46d3567SJeff Layton retry: 4034f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40351da177e4SLinus Torvalds error = PTR_ERR(dentry); 40366902d925SDave Hansen if (IS_ERR(dentry)) 4037dae6ad8fSAl Viro goto out_putname; 40386902d925SDave Hansen 403991a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4040a8104a9fSAl Viro if (!error) 404191a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4042921a1650SAl Viro done_path_create(&path, dentry); 4043f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4044f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4045f46d3567SJeff Layton goto retry; 4046f46d3567SJeff Layton } 40476902d925SDave Hansen out_putname: 40481da177e4SLinus Torvalds putname(from); 40491da177e4SLinus Torvalds return error; 40501da177e4SLinus Torvalds } 40511da177e4SLinus Torvalds 4052b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4053b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4054b724e846SDominik Brodowski { 4055b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4056b724e846SDominik Brodowski } 4057b724e846SDominik Brodowski 40583480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40595590ff0dSUlrich Drepper { 4060b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 40615590ff0dSUlrich Drepper } 40625590ff0dSUlrich Drepper 4063146a8595SJ. Bruce Fields /** 4064146a8595SJ. Bruce Fields * vfs_link - create a new link 4065146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4066146a8595SJ. Bruce Fields * @dir: new parent 4067146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4068146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4069146a8595SJ. Bruce Fields * 4070146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4071146a8595SJ. Bruce Fields * 4072146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4073146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4074146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4075146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4076146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4077146a8595SJ. Bruce Fields * 4078146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4079146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4080146a8595SJ. Bruce Fields * to be NFS exported. 4081146a8595SJ. Bruce Fields */ 4082146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40831da177e4SLinus Torvalds { 40841da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40858de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40861da177e4SLinus Torvalds int error; 40871da177e4SLinus Torvalds 40881da177e4SLinus Torvalds if (!inode) 40891da177e4SLinus Torvalds return -ENOENT; 40901da177e4SLinus Torvalds 4091a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40921da177e4SLinus Torvalds if (error) 40931da177e4SLinus Torvalds return error; 40941da177e4SLinus Torvalds 40951da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40961da177e4SLinus Torvalds return -EXDEV; 40971da177e4SLinus Torvalds 40981da177e4SLinus Torvalds /* 40991da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41001da177e4SLinus Torvalds */ 41011da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41021da177e4SLinus Torvalds return -EPERM; 41030bd23d09SEric W. Biederman /* 41040bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41050bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41060bd23d09SEric W. Biederman * the vfs. 41070bd23d09SEric W. Biederman */ 41080bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41090bd23d09SEric W. Biederman return -EPERM; 4110acfa4380SAl Viro if (!dir->i_op->link) 41111da177e4SLinus Torvalds return -EPERM; 41127e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41131da177e4SLinus Torvalds return -EPERM; 41141da177e4SLinus Torvalds 41151da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41161da177e4SLinus Torvalds if (error) 41171da177e4SLinus Torvalds return error; 41181da177e4SLinus Torvalds 41195955102cSAl Viro inode_lock(inode); 4120aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4121f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4122aae8a97dSAneesh Kumar K.V error = -ENOENT; 41238de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41248de52778SAl Viro error = -EMLINK; 4125146a8595SJ. Bruce Fields else { 4126146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4127146a8595SJ. Bruce Fields if (!error) 41281da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4129146a8595SJ. Bruce Fields } 4130f4e0c30cSAl Viro 4131f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4132f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4133f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4134f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4135f4e0c30cSAl Viro } 41365955102cSAl Viro inode_unlock(inode); 4137e31e14ecSStephen Smalley if (!error) 41387e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41391da177e4SLinus Torvalds return error; 41401da177e4SLinus Torvalds } 41414d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41421da177e4SLinus Torvalds 41431da177e4SLinus Torvalds /* 41441da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41451da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41461da177e4SLinus Torvalds * newname. --KAB 41471da177e4SLinus Torvalds * 41481da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41491da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41501da177e4SLinus Torvalds * and other special files. --ADM 41511da177e4SLinus Torvalds */ 4152812931d6SChristoph Hellwig static int do_linkat(int olddfd, const char __user *oldname, int newdfd, 415346ea89ebSDominik Brodowski const char __user *newname, int flags) 41541da177e4SLinus Torvalds { 41551da177e4SLinus Torvalds struct dentry *new_dentry; 4156dae6ad8fSAl Viro struct path old_path, new_path; 4157146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 415811a7b371SAneesh Kumar K.V int how = 0; 41591da177e4SLinus Torvalds int error; 41601da177e4SLinus Torvalds 416111a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4162c04030e1SUlrich Drepper return -EINVAL; 416311a7b371SAneesh Kumar K.V /* 4164f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4165f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4166f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 416711a7b371SAneesh Kumar K.V */ 4168f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4169f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4170f0cc6ffbSLinus Torvalds return -ENOENT; 417111a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4172f0cc6ffbSLinus Torvalds } 4173c04030e1SUlrich Drepper 417411a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 417511a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4176442e31caSJeff Layton retry: 417711a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41781da177e4SLinus Torvalds if (error) 41792ad94ae6SAl Viro return error; 41802ad94ae6SAl Viro 4181442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4182442e31caSJeff Layton (how & LOOKUP_REVAL)); 41831da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41846902d925SDave Hansen if (IS_ERR(new_dentry)) 4185dae6ad8fSAl Viro goto out; 4186dae6ad8fSAl Viro 4187dae6ad8fSAl Viro error = -EXDEV; 4188dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4189dae6ad8fSAl Viro goto out_dput; 4190800179c9SKees Cook error = may_linkat(&old_path); 4191800179c9SKees Cook if (unlikely(error)) 4192800179c9SKees Cook goto out_dput; 4193dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4194be6d3e56SKentaro Takeda if (error) 4195a8104a9fSAl Viro goto out_dput; 4196146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 419775c3f29dSDave Hansen out_dput: 4198921a1650SAl Viro done_path_create(&new_path, new_dentry); 4199146a8595SJ. Bruce Fields if (delegated_inode) { 4200146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4201d22e6338SOleg Drokin if (!error) { 4202d22e6338SOleg Drokin path_put(&old_path); 4203146a8595SJ. Bruce Fields goto retry; 4204146a8595SJ. Bruce Fields } 4205d22e6338SOleg Drokin } 4206442e31caSJeff Layton if (retry_estale(error, how)) { 4207d22e6338SOleg Drokin path_put(&old_path); 4208442e31caSJeff Layton how |= LOOKUP_REVAL; 4209442e31caSJeff Layton goto retry; 4210442e31caSJeff Layton } 42111da177e4SLinus Torvalds out: 42122d8f3038SAl Viro path_put(&old_path); 42131da177e4SLinus Torvalds 42141da177e4SLinus Torvalds return error; 42151da177e4SLinus Torvalds } 42161da177e4SLinus Torvalds 421746ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 421846ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 421946ea89ebSDominik Brodowski { 422046ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 422146ea89ebSDominik Brodowski } 422246ea89ebSDominik Brodowski 42233480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42245590ff0dSUlrich Drepper { 422546ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42265590ff0dSUlrich Drepper } 42275590ff0dSUlrich Drepper 4228bc27027aSMiklos Szeredi /** 4229bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4230bc27027aSMiklos Szeredi * @old_dir: parent of source 4231bc27027aSMiklos Szeredi * @old_dentry: source 4232bc27027aSMiklos Szeredi * @new_dir: parent of destination 4233bc27027aSMiklos Szeredi * @new_dentry: destination 4234bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4235520c8b16SMiklos Szeredi * @flags: rename flags 4236bc27027aSMiklos Szeredi * 4237bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4238bc27027aSMiklos Szeredi * 4239bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4240bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4241bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4242bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4243bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4244bc27027aSMiklos Szeredi * so. 4245bc27027aSMiklos Szeredi * 4246bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4247bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4248bc27027aSMiklos Szeredi * to be NFS exported. 4249bc27027aSMiklos Szeredi * 42501da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42511da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42521da177e4SLinus Torvalds * Problems: 42530117d427SMauro Carvalho Chehab * 4254d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42551da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42561da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4257a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42581da177e4SLinus Torvalds * story. 42596cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42606cedba89SJ. Bruce Fields * and source (if it is not a directory). 42611b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42621da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42631da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4264a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42651da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42661da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42671da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4268a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42691da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42701da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42711da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4272e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42731b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42741da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4275c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42761da177e4SLinus Torvalds * locking]. 42771da177e4SLinus Torvalds */ 42781da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42798e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4280520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42811da177e4SLinus Torvalds { 42821da177e4SLinus Torvalds int error; 4283bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4284bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4285bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4286da1ce067SMiklos Szeredi bool new_is_dir = false; 4287da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 428849d31c2fSAl Viro struct name_snapshot old_name; 42891da177e4SLinus Torvalds 42908d3e2936SMiklos Szeredi if (source == target) 42911da177e4SLinus Torvalds return 0; 42921da177e4SLinus Torvalds 42931da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42941da177e4SLinus Torvalds if (error) 42951da177e4SLinus Torvalds return error; 42961da177e4SLinus Torvalds 4297da1ce067SMiklos Szeredi if (!target) { 4298a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4299da1ce067SMiklos Szeredi } else { 4300da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4301da1ce067SMiklos Szeredi 4302da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43031da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4304da1ce067SMiklos Szeredi else 4305da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4306da1ce067SMiklos Szeredi } 43071da177e4SLinus Torvalds if (error) 43081da177e4SLinus Torvalds return error; 43091da177e4SLinus Torvalds 43102773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43111da177e4SLinus Torvalds return -EPERM; 43121da177e4SLinus Torvalds 4313bc27027aSMiklos Szeredi /* 4314bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4315bc27027aSMiklos Szeredi * we'll need to flip '..'. 4316bc27027aSMiklos Szeredi */ 4317da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4318da1ce067SMiklos Szeredi if (is_dir) { 4319*47291baaSChristian Brauner error = inode_permission(&init_user_ns, source, 4320*47291baaSChristian Brauner MAY_WRITE); 4321bc27027aSMiklos Szeredi if (error) 4322bc27027aSMiklos Szeredi return error; 4323bc27027aSMiklos Szeredi } 4324da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4325*47291baaSChristian Brauner error = inode_permission(&init_user_ns, target, 4326*47291baaSChristian Brauner MAY_WRITE); 4327da1ce067SMiklos Szeredi if (error) 4328da1ce067SMiklos Szeredi return error; 4329da1ce067SMiklos Szeredi } 4330da1ce067SMiklos Szeredi } 43310eeca283SRobert Love 43320b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43330b3974ebSMiklos Szeredi flags); 4334bc27027aSMiklos Szeredi if (error) 4335bc27027aSMiklos Szeredi return error; 4336bc27027aSMiklos Szeredi 433749d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4338bc27027aSMiklos Szeredi dget(new_dentry); 4339da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4340bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4341bc27027aSMiklos Szeredi else if (target) 43425955102cSAl Viro inode_lock(target); 4343bc27027aSMiklos Szeredi 4344bc27027aSMiklos Szeredi error = -EBUSY; 43457af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4346bc27027aSMiklos Szeredi goto out; 4347bc27027aSMiklos Szeredi 4348da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4349bc27027aSMiklos Szeredi error = -EMLINK; 4350da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4351bc27027aSMiklos Szeredi goto out; 4352da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4353da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4354da1ce067SMiklos Szeredi goto out; 4355da1ce067SMiklos Szeredi } 4356da1ce067SMiklos Szeredi if (!is_dir) { 4357bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4358bc27027aSMiklos Szeredi if (error) 4359bc27027aSMiklos Szeredi goto out; 4360da1ce067SMiklos Szeredi } 4361da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4362bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4363bc27027aSMiklos Szeredi if (error) 4364bc27027aSMiklos Szeredi goto out; 4365bc27027aSMiklos Szeredi } 4366520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4367520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4368bc27027aSMiklos Szeredi if (error) 4369bc27027aSMiklos Szeredi goto out; 4370bc27027aSMiklos Szeredi 4371da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43728767712fSAl Viro if (is_dir) { 43738767712fSAl Viro shrink_dcache_parent(new_dentry); 4374bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 43758767712fSAl Viro } 4376bc27027aSMiklos Szeredi dont_mount(new_dentry); 43778ed936b5SEric W. Biederman detach_mounts(new_dentry); 4378bc27027aSMiklos Szeredi } 4379da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4380da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4381bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4382da1ce067SMiklos Szeredi else 4383da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4384da1ce067SMiklos Szeredi } 4385bc27027aSMiklos Szeredi out: 4386da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4387bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4388bc27027aSMiklos Szeredi else if (target) 43895955102cSAl Viro inode_unlock(target); 4390bc27027aSMiklos Szeredi dput(new_dentry); 4391da1ce067SMiklos Szeredi if (!error) { 4392f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4393da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4394da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4395f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4396da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4397da1ce067SMiklos Szeredi } 4398da1ce067SMiklos Szeredi } 439949d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 44000eeca283SRobert Love 44011da177e4SLinus Torvalds return error; 44021da177e4SLinus Torvalds } 44034d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44041da177e4SLinus Torvalds 4405e886663cSJens Axboe int do_renameat2(int olddfd, struct filename *from, int newdfd, 4406e886663cSJens Axboe struct filename *to, unsigned int flags) 44071da177e4SLinus Torvalds { 44081da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44091da177e4SLinus Torvalds struct dentry *trap; 4410f5beed75SAl Viro struct path old_path, new_path; 4411f5beed75SAl Viro struct qstr old_last, new_last; 4412f5beed75SAl Viro int old_type, new_type; 44138e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 4414f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4415c6a94284SJeff Layton bool should_retry = false; 4416e886663cSJens Axboe int error = -EINVAL; 4417520c8b16SMiklos Szeredi 44180d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4419e886663cSJens Axboe goto put_both; 4420da1ce067SMiklos Szeredi 44210d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44220d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4423e886663cSJens Axboe goto put_both; 4424520c8b16SMiklos Szeredi 4425f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4426f5beed75SAl Viro target_flags = 0; 4427f5beed75SAl Viro 4428c6a94284SJeff Layton retry: 4429e886663cSJens Axboe from = filename_parentat(olddfd, from, lookup_flags, &old_path, 4430e886663cSJens Axboe &old_last, &old_type); 443191a27b2aSJeff Layton if (IS_ERR(from)) { 443291a27b2aSJeff Layton error = PTR_ERR(from); 4433e886663cSJens Axboe goto put_new; 443491a27b2aSJeff Layton } 44351da177e4SLinus Torvalds 4436e886663cSJens Axboe to = filename_parentat(newdfd, to, lookup_flags, &new_path, &new_last, 4437e886663cSJens Axboe &new_type); 443891a27b2aSJeff Layton if (IS_ERR(to)) { 443991a27b2aSJeff Layton error = PTR_ERR(to); 44401da177e4SLinus Torvalds goto exit1; 444191a27b2aSJeff Layton } 44421da177e4SLinus Torvalds 44431da177e4SLinus Torvalds error = -EXDEV; 4444f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44451da177e4SLinus Torvalds goto exit2; 44461da177e4SLinus Torvalds 44471da177e4SLinus Torvalds error = -EBUSY; 4448f5beed75SAl Viro if (old_type != LAST_NORM) 44491da177e4SLinus Torvalds goto exit2; 44501da177e4SLinus Torvalds 44510a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44520a7c3937SMiklos Szeredi error = -EEXIST; 4453f5beed75SAl Viro if (new_type != LAST_NORM) 44541da177e4SLinus Torvalds goto exit2; 44551da177e4SLinus Torvalds 4456f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4457c30dabfeSJan Kara if (error) 4458c30dabfeSJan Kara goto exit2; 4459c30dabfeSJan Kara 44608e6d782cSJ. Bruce Fields retry_deleg: 4461f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44621da177e4SLinus Torvalds 4463f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44641da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44651da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44661da177e4SLinus Torvalds goto exit3; 44671da177e4SLinus Torvalds /* source must exist */ 44681da177e4SLinus Torvalds error = -ENOENT; 4469b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44701da177e4SLinus Torvalds goto exit4; 4471f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44721da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44731da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44741da177e4SLinus Torvalds goto exit4; 44750a7c3937SMiklos Szeredi error = -EEXIST; 44760a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44770a7c3937SMiklos Szeredi goto exit5; 4478da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4479da1ce067SMiklos Szeredi error = -ENOENT; 4480da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4481da1ce067SMiklos Szeredi goto exit5; 4482da1ce067SMiklos Szeredi 4483da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4484da1ce067SMiklos Szeredi error = -ENOTDIR; 4485f5beed75SAl Viro if (new_last.name[new_last.len]) 4486da1ce067SMiklos Szeredi goto exit5; 4487da1ce067SMiklos Szeredi } 4488da1ce067SMiklos Szeredi } 44890a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44900a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44910a7c3937SMiklos Szeredi error = -ENOTDIR; 4492f5beed75SAl Viro if (old_last.name[old_last.len]) 44930a7c3937SMiklos Szeredi goto exit5; 4494f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44950a7c3937SMiklos Szeredi goto exit5; 44960a7c3937SMiklos Szeredi } 44970a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44980a7c3937SMiklos Szeredi error = -EINVAL; 44990a7c3937SMiklos Szeredi if (old_dentry == trap) 45000a7c3937SMiklos Szeredi goto exit5; 45011da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4502da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45031da177e4SLinus Torvalds error = -ENOTEMPTY; 45041da177e4SLinus Torvalds if (new_dentry == trap) 45051da177e4SLinus Torvalds goto exit5; 45061da177e4SLinus Torvalds 4507f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4508f5beed75SAl Viro &new_path, new_dentry, flags); 4509be6d3e56SKentaro Takeda if (error) 4510c30dabfeSJan Kara goto exit5; 4511f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4512f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4513520c8b16SMiklos Szeredi &delegated_inode, flags); 45141da177e4SLinus Torvalds exit5: 45151da177e4SLinus Torvalds dput(new_dentry); 45161da177e4SLinus Torvalds exit4: 45171da177e4SLinus Torvalds dput(old_dentry); 45181da177e4SLinus Torvalds exit3: 4519f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45208e6d782cSJ. Bruce Fields if (delegated_inode) { 45218e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45228e6d782cSJ. Bruce Fields if (!error) 45238e6d782cSJ. Bruce Fields goto retry_deleg; 45248e6d782cSJ. Bruce Fields } 4525f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45261da177e4SLinus Torvalds exit2: 4527c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4528c6a94284SJeff Layton should_retry = true; 4529f5beed75SAl Viro path_put(&new_path); 45301da177e4SLinus Torvalds exit1: 4531f5beed75SAl Viro path_put(&old_path); 4532c6a94284SJeff Layton if (should_retry) { 4533c6a94284SJeff Layton should_retry = false; 4534c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4535c6a94284SJeff Layton goto retry; 4536c6a94284SJeff Layton } 4537e886663cSJens Axboe put_both: 4538e886663cSJens Axboe if (!IS_ERR(from)) 4539e886663cSJens Axboe putname(from); 4540e886663cSJens Axboe put_new: 4541e886663cSJens Axboe if (!IS_ERR(to)) 4542e886663cSJens Axboe putname(to); 45431da177e4SLinus Torvalds return error; 45441da177e4SLinus Torvalds } 45451da177e4SLinus Torvalds 4546ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4547ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4548ee81feb6SDominik Brodowski { 4549e886663cSJens Axboe return do_renameat2(olddfd, getname(oldname), newdfd, getname(newname), 4550e886663cSJens Axboe flags); 4551ee81feb6SDominik Brodowski } 4552ee81feb6SDominik Brodowski 4553520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4554520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4555520c8b16SMiklos Szeredi { 4556e886663cSJens Axboe return do_renameat2(olddfd, getname(oldname), newdfd, getname(newname), 4557e886663cSJens Axboe 0); 4558520c8b16SMiklos Szeredi } 4559520c8b16SMiklos Szeredi 4560a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45615590ff0dSUlrich Drepper { 4562e886663cSJens Axboe return do_renameat2(AT_FDCWD, getname(oldname), AT_FDCWD, 4563e886663cSJens Axboe getname(newname), 0); 45645590ff0dSUlrich Drepper } 45655590ff0dSUlrich Drepper 45665d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45671da177e4SLinus Torvalds { 45685d826c84SAl Viro int len = PTR_ERR(link); 45691da177e4SLinus Torvalds if (IS_ERR(link)) 45701da177e4SLinus Torvalds goto out; 45711da177e4SLinus Torvalds 45721da177e4SLinus Torvalds len = strlen(link); 45731da177e4SLinus Torvalds if (len > (unsigned) buflen) 45741da177e4SLinus Torvalds len = buflen; 45751da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45761da177e4SLinus Torvalds len = -EFAULT; 45771da177e4SLinus Torvalds out: 45781da177e4SLinus Torvalds return len; 45791da177e4SLinus Torvalds } 45801da177e4SLinus Torvalds 4581d60874cdSMiklos Szeredi /** 4582fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4583fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4584fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4585fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4586fd4a0edfSMiklos Szeredi * 4587fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4588fd4a0edfSMiklos Szeredi * 4589fd4a0edfSMiklos Szeredi * Does not call security hook. 4590fd4a0edfSMiklos Szeredi */ 4591fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4592fd4a0edfSMiklos Szeredi { 4593fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4594f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4595f2df5da6SAl Viro const char *link; 4596f2df5da6SAl Viro int res; 4597fd4a0edfSMiklos Szeredi 459876fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 459976fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 460076fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 460176fca90eSMiklos Szeredi 460276fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4603fd4a0edfSMiklos Szeredi return -EINVAL; 4604fd4a0edfSMiklos Szeredi 460576fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 460676fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 460776fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 460876fca90eSMiklos Szeredi } 460976fca90eSMiklos Szeredi 46104c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4611f2df5da6SAl Viro if (!link) { 4612f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4613f2df5da6SAl Viro if (IS_ERR(link)) 4614f2df5da6SAl Viro return PTR_ERR(link); 4615f2df5da6SAl Viro } 4616f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4617f2df5da6SAl Viro do_delayed_call(&done); 4618f2df5da6SAl Viro return res; 4619fd4a0edfSMiklos Szeredi } 4620fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46211da177e4SLinus Torvalds 4622d60874cdSMiklos Szeredi /** 4623d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4624d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4625d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4626d60874cdSMiklos Szeredi * 4627d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4628d60874cdSMiklos Szeredi * 4629d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4630d60874cdSMiklos Szeredi * 4631d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4632d60874cdSMiklos Szeredi */ 4633d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4634d60874cdSMiklos Szeredi { 4635d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4636d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4637d60874cdSMiklos Szeredi 4638d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4639d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4640d60874cdSMiklos Szeredi if (!res) 4641d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4642d60874cdSMiklos Szeredi } 4643d60874cdSMiklos Szeredi return res; 4644d60874cdSMiklos Szeredi } 4645d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4646d60874cdSMiklos Szeredi 46471da177e4SLinus Torvalds /* get the link contents into pagecache */ 46486b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4649fceef393SAl Viro struct delayed_call *callback) 46501da177e4SLinus Torvalds { 4651ebd09abbSDuane Griffin char *kaddr; 46521da177e4SLinus Torvalds struct page *page; 46536b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46546b255391SAl Viro 4655d3883d4fSAl Viro if (!dentry) { 4656d3883d4fSAl Viro page = find_get_page(mapping, 0); 4657d3883d4fSAl Viro if (!page) 46586b255391SAl Viro return ERR_PTR(-ECHILD); 4659d3883d4fSAl Viro if (!PageUptodate(page)) { 4660d3883d4fSAl Viro put_page(page); 4661d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4662d3883d4fSAl Viro } 4663d3883d4fSAl Viro } else { 4664090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46651da177e4SLinus Torvalds if (IS_ERR(page)) 46666fe6900eSNick Piggin return (char*)page; 4667d3883d4fSAl Viro } 4668fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 466921fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 467021fc61c7SAl Viro kaddr = page_address(page); 46716b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4672ebd09abbSDuane Griffin return kaddr; 46731da177e4SLinus Torvalds } 46741da177e4SLinus Torvalds 46756b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46761da177e4SLinus Torvalds 4677fceef393SAl Viro void page_put_link(void *arg) 46781da177e4SLinus Torvalds { 4679fceef393SAl Viro put_page(arg); 46801da177e4SLinus Torvalds } 46814d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46821da177e4SLinus Torvalds 4683aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4684aa80deabSAl Viro { 4685fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46866b255391SAl Viro int res = readlink_copy(buffer, buflen, 46876b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4688fceef393SAl Viro &done)); 4689fceef393SAl Viro do_delayed_call(&done); 4690aa80deabSAl Viro return res; 4691aa80deabSAl Viro } 4692aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4693aa80deabSAl Viro 469454566b2cSNick Piggin /* 469554566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 469654566b2cSNick Piggin */ 469754566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 46981da177e4SLinus Torvalds { 46991da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47000adb25d2SKirill Korotaev struct page *page; 4701afddba49SNick Piggin void *fsdata; 4702beb497abSDmitriy Monakhov int err; 4703c718a975STetsuo Handa unsigned int flags = 0; 470454566b2cSNick Piggin if (nofs) 470554566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47061da177e4SLinus Torvalds 47077e53cac4SNeilBrown retry: 4708afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 470954566b2cSNick Piggin flags, &page, &fsdata); 47101da177e4SLinus Torvalds if (err) 4711afddba49SNick Piggin goto fail; 4712afddba49SNick Piggin 471321fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4714afddba49SNick Piggin 4715afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4716afddba49SNick Piggin page, fsdata); 47171da177e4SLinus Torvalds if (err < 0) 47181da177e4SLinus Torvalds goto fail; 4719afddba49SNick Piggin if (err < len-1) 4720afddba49SNick Piggin goto retry; 4721afddba49SNick Piggin 47221da177e4SLinus Torvalds mark_inode_dirty(inode); 47231da177e4SLinus Torvalds return 0; 47241da177e4SLinus Torvalds fail: 47251da177e4SLinus Torvalds return err; 47261da177e4SLinus Torvalds } 47274d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47281da177e4SLinus Torvalds 47290adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47300adb25d2SKirill Korotaev { 47310adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4732c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47330adb25d2SKirill Korotaev } 47344d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47350adb25d2SKirill Korotaev 473692e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47376b255391SAl Viro .get_link = page_get_link, 47381da177e4SLinus Torvalds }; 47391da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4740