4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * Some corrections by tytso.
11 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
14 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
21 #include <linux/namei.h>
22 #include <linux/pagemap.h>
23 #include <linux/fsnotify.h>
24 #include <linux/personality.h>
25 #include <linux/security.h>
26 #include <linux/ima.h>
27 #include <linux/syscalls.h>
28 #include <linux/mount.h>
29 #include <linux/audit.h>
30 #include <linux/capability.h>
31 #include <linux/file.h>
32 #include <linux/fcntl.h>
33 #include <linux/device_cgroup.h>
34 #include <linux/fs_struct.h>
35 #include <linux/posix_acl.h>
36 #include <asm/uaccess.h>
40 /* [Feb-1997 T. Schoebel-Theuer]
41 * Fundamental changes in the pathname lookup mechanisms (namei)
42 * were necessary because of omirr. The reason is that omirr needs
43 * to know the _real_ pathname, not the user-supplied one, in case
44 * of symlinks (and also when transname replacements occur).
46 * The new code replaces the old recursive symlink resolution with
47 * an iterative one (in case of non-nested symlink chains). It does
48 * this with calls to <fs>_follow_link().
49 * As a side effect, dir_namei(), _namei() and follow_link() are now
50 * replaced with a single function lookup_dentry() that can handle all
51 * the special cases of the former code.
53 * With the new dcache, the pathname is stored at each inode, at least as
54 * long as the refcount of the inode is positive. As a side effect, the
55 * size of the dcache depends on the inode cache and thus is dynamic.
57 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
58 * resolution to correspond with current state of the code.
60 * Note that the symlink resolution is not *completely* iterative.
61 * There is still a significant amount of tail- and mid- recursion in
62 * the algorithm. Also, note that <fs>_readlink() is not used in
63 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
64 * may return different results than <fs>_follow_link(). Many virtual
65 * filesystems (including /proc) exhibit this behavior.
68 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
69 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
70 * and the name already exists in form of a symlink, try to create the new
71 * name indicated by the symlink. The old code always complained that the
72 * name already exists, due to not following the symlink even if its target
73 * is nonexistent. The new semantics affects also mknod() and link() when
74 * the name is a symlink pointing to a non-existent name.
76 * I don't know which semantics is the right one, since I have no access
77 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
78 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
79 * "old" one. Personally, I think the new semantics is much more logical.
80 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
81 * file does succeed in both HP-UX and SunOs, but not in Solaris
82 * and in the old Linux semantics.
85 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
86 * semantics. See the comments in "open_namei" and "do_link" below.
88 * [10-Sep-98 Alan Modra] Another symlink change.
91 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
92 * inside the path - always follow.
93 * in the last component in creation/removal/renaming - never follow.
94 * if LOOKUP_FOLLOW passed - follow.
95 * if the pathname has trailing slashes - follow.
96 * otherwise - don't follow.
97 * (applied in that order).
99 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
100 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
101 * During the 2.4 we need to fix the userland stuff depending on it -
102 * hopefully we will be able to get rid of that wart in 2.5. So far only
103 * XEmacs seems to be relying on it...
106 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
107 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
108 * any extra contention...
111 /* In order to reduce some races, while at the same time doing additional
112 * checking and hopefully speeding things up, we copy filenames to the
113 * kernel data space before using them..
115 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
116 * PATH_MAX includes the nul terminator --RR.
118 static int do_getname(const char __user *filename, char *page)
121 unsigned long len = PATH_MAX;
123 if (!segment_eq(get_fs(), KERNEL_DS)) {
124 if ((unsigned long) filename >= TASK_SIZE)
126 if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
127 len = TASK_SIZE - (unsigned long) filename;
130 retval = strncpy_from_user(page, filename, len);
134 return -ENAMETOOLONG;
140 static char *getname_flags(const char __user * filename, int flags)
144 result = ERR_PTR(-ENOMEM);
147 int retval = do_getname(filename, tmp);
151 if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) {
153 result = ERR_PTR(retval);
157 audit_getname(result);
161 char *getname(const char __user * filename)
163 return getname_flags(filename, 0);
166 #ifdef CONFIG_AUDITSYSCALL
167 void putname(const char *name)
169 if (unlikely(!audit_dummy_context()))
174 EXPORT_SYMBOL(putname);
177 static int check_acl(struct inode *inode, int mask)
179 struct posix_acl *acl;
182 * Under RCU walk, we cannot even do a "get_cached_acl()",
183 * because that involves locking and getting a refcount on
186 * So the only case we handle during RCU walking is the
187 * case of a cached "no ACL at all", which needs no locks
190 if (mask & MAY_NOT_BLOCK) {
191 if (negative_cached_acl(inode, ACL_TYPE_ACCESS))
196 acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
199 * A filesystem can force a ACL callback by just never
200 * filling the ACL cache. But normally you'd fill the
201 * cache either at inode instantiation time, or on the
202 * first ->check_acl call.
204 * If the filesystem doesn't have a check_acl() function
205 * at all, we'll just create the negative cache entry.
207 if (acl == ACL_NOT_CACHED) {
208 if (inode->i_op->check_acl)
209 return inode->i_op->check_acl(inode, mask);
211 set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
216 int error = posix_acl_permission(inode, acl, mask);
217 posix_acl_release(acl);
225 * This does basic POSIX ACL permission checking
227 static int acl_permission_check(struct inode *inode, int mask)
229 unsigned int mode = inode->i_mode;
231 mask &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
233 if (current_user_ns() != inode_userns(inode))
236 if (current_fsuid() == inode->i_uid)
239 if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
240 int error = check_acl(inode, mask);
241 if (error != -EAGAIN)
245 if (in_group_p(inode->i_gid))
251 * If the DACs are ok we don't need any capability check.
253 if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
259 * generic_permission - check for access rights on a Posix-like filesystem
260 * @inode: inode to check access rights for
261 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
263 * Used to check for read/write/execute permissions on a file.
264 * We use "fsuid" for this, letting us set arbitrary permissions
265 * for filesystem access without changing the "normal" uids which
266 * are used for other things.
268 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
269 * request cannot be satisfied (eg. requires blocking or too much complexity).
270 * It would then be called again in ref-walk mode.
272 int generic_permission(struct inode *inode, int mask)
277 * Do the basic POSIX ACL permission checks.
279 ret = acl_permission_check(inode, mask);
283 if (S_ISDIR(inode->i_mode)) {
284 /* DACs are overridable for directories */
285 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
287 if (!(mask & MAY_WRITE))
288 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
293 * Read/write DACs are always overridable.
294 * Executable DACs are overridable when there is
295 * at least one exec bit set.
297 if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
298 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
302 * Searching includes executable on directories, else just read.
304 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
305 if (mask == MAY_READ)
306 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
313 * inode_permission - check for access rights to a given inode
314 * @inode: inode to check permission on
315 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
317 * Used to check for read/write/execute permissions on an inode.
318 * We use "fsuid" for this, letting us set arbitrary permissions
319 * for filesystem access without changing the "normal" uids which
320 * are used for other things.
322 int inode_permission(struct inode *inode, int mask)
326 if (mask & MAY_WRITE) {
327 umode_t mode = inode->i_mode;
330 * Nobody gets write access to a read-only fs.
332 if (IS_RDONLY(inode) &&
333 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
337 * Nobody gets write access to an immutable file.
339 if (IS_IMMUTABLE(inode))
343 if (inode->i_op->permission)
344 retval = inode->i_op->permission(inode, mask);
346 retval = generic_permission(inode, mask);
351 retval = devcgroup_inode_permission(inode, mask);
355 return security_inode_permission(inode, mask);
359 * path_get - get a reference to a path
360 * @path: path to get the reference to
362 * Given a path increment the reference count to the dentry and the vfsmount.
364 void path_get(struct path *path)
369 EXPORT_SYMBOL(path_get);
372 * path_put - put a reference to a path
373 * @path: path to put the reference to
375 * Given a path decrement the reference count to the dentry and the vfsmount.
377 void path_put(struct path *path)
382 EXPORT_SYMBOL(path_put);
385 * Path walking has 2 modes, rcu-walk and ref-walk (see
386 * Documentation/filesystems/path-lookup.txt). In situations when we can't
387 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
388 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
389 * mode. Refcounts are grabbed at the last known good point before rcu-walk
390 * got stuck, so ref-walk may continue from there. If this is not successful
391 * (eg. a seqcount has changed), then failure is returned and it's up to caller
392 * to restart the path walk from the beginning in ref-walk mode.
396 * unlazy_walk - try to switch to ref-walk mode.
397 * @nd: nameidata pathwalk data
398 * @dentry: child of nd->path.dentry or NULL
399 * Returns: 0 on success, -ECHILD on failure
401 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
402 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
403 * @nd or NULL. Must be called from rcu-walk context.
405 static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
407 struct fs_struct *fs = current->fs;
408 struct dentry *parent = nd->path.dentry;
411 BUG_ON(!(nd->flags & LOOKUP_RCU));
412 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
414 spin_lock(&fs->lock);
415 if (nd->root.mnt != fs->root.mnt ||
416 nd->root.dentry != fs->root.dentry)
419 spin_lock(&parent->d_lock);
421 if (!__d_rcu_to_refcount(parent, nd->seq))
423 BUG_ON(nd->inode != parent->d_inode);
425 if (dentry->d_parent != parent)
427 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
428 if (!__d_rcu_to_refcount(dentry, nd->seq))
431 * If the sequence check on the child dentry passed, then
432 * the child has not been removed from its parent. This
433 * means the parent dentry must be valid and able to take
434 * a reference at this point.
436 BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent);
437 BUG_ON(!parent->d_count);
439 spin_unlock(&dentry->d_lock);
441 spin_unlock(&parent->d_lock);
444 spin_unlock(&fs->lock);
446 mntget(nd->path.mnt);
449 br_read_unlock(vfsmount_lock);
450 nd->flags &= ~LOOKUP_RCU;
454 spin_unlock(&dentry->d_lock);
456 spin_unlock(&parent->d_lock);
459 spin_unlock(&fs->lock);
464 * release_open_intent - free up open intent resources
465 * @nd: pointer to nameidata
467 void release_open_intent(struct nameidata *nd)
469 struct file *file = nd->intent.open.file;
471 if (file && !IS_ERR(file)) {
472 if (file->f_path.dentry == NULL)
479 static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
481 return dentry->d_op->d_revalidate(dentry, nd);
485 * complete_walk - successful completion of path walk
486 * @nd: pointer nameidata
488 * If we had been in RCU mode, drop out of it and legitimize nd->path.
489 * Revalidate the final result, unless we'd already done that during
490 * the path walk or the filesystem doesn't ask for it. Return 0 on
491 * success, -error on failure. In case of failure caller does not
492 * need to drop nd->path.
494 static int complete_walk(struct nameidata *nd)
496 struct dentry *dentry = nd->path.dentry;
499 if (nd->flags & LOOKUP_RCU) {
500 nd->flags &= ~LOOKUP_RCU;
501 if (!(nd->flags & LOOKUP_ROOT))
503 spin_lock(&dentry->d_lock);
504 if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
505 spin_unlock(&dentry->d_lock);
507 br_read_unlock(vfsmount_lock);
510 BUG_ON(nd->inode != dentry->d_inode);
511 spin_unlock(&dentry->d_lock);
512 mntget(nd->path.mnt);
514 br_read_unlock(vfsmount_lock);
517 if (likely(!(nd->flags & LOOKUP_JUMPED)))
520 if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
523 if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
526 /* Note: we do not d_invalidate() */
527 status = d_revalidate(dentry, nd);
538 static __always_inline void set_root(struct nameidata *nd)
541 get_fs_root(current->fs, &nd->root);
544 static int link_path_walk(const char *, struct nameidata *);
546 static __always_inline void set_root_rcu(struct nameidata *nd)
549 struct fs_struct *fs = current->fs;
553 seq = read_seqcount_begin(&fs->seq);
555 nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
556 } while (read_seqcount_retry(&fs->seq, seq));
560 static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
572 nd->flags |= LOOKUP_JUMPED;
574 nd->inode = nd->path.dentry->d_inode;
576 ret = link_path_walk(link, nd);
580 return PTR_ERR(link);
583 static void path_put_conditional(struct path *path, struct nameidata *nd)
586 if (path->mnt != nd->path.mnt)
590 static inline void path_to_nameidata(const struct path *path,
591 struct nameidata *nd)
593 if (!(nd->flags & LOOKUP_RCU)) {
594 dput(nd->path.dentry);
595 if (nd->path.mnt != path->mnt)
596 mntput(nd->path.mnt);
598 nd->path.mnt = path->mnt;
599 nd->path.dentry = path->dentry;
602 static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
604 struct inode *inode = link->dentry->d_inode;
605 if (!IS_ERR(cookie) && inode->i_op->put_link)
606 inode->i_op->put_link(link->dentry, nd, cookie);
610 static __always_inline int
611 follow_link(struct path *link, struct nameidata *nd, void **p)
614 struct dentry *dentry = link->dentry;
616 BUG_ON(nd->flags & LOOKUP_RCU);
618 if (link->mnt == nd->path.mnt)
621 if (unlikely(current->total_link_count >= 40)) {
622 *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
627 current->total_link_count++;
629 touch_atime(link->mnt, dentry);
630 nd_set_link(nd, NULL);
632 error = security_inode_follow_link(link->dentry, nd);
634 *p = ERR_PTR(error); /* no ->put_link(), please */
639 nd->last_type = LAST_BIND;
640 *p = dentry->d_inode->i_op->follow_link(dentry, nd);
643 char *s = nd_get_link(nd);
646 error = __vfs_follow_link(nd, s);
647 else if (nd->last_type == LAST_BIND) {
648 nd->flags |= LOOKUP_JUMPED;
649 nd->inode = nd->path.dentry->d_inode;
650 if (nd->inode->i_op->follow_link) {
651 /* stepped on a _really_ weird one */
660 static int follow_up_rcu(struct path *path)
662 struct vfsmount *parent;
663 struct dentry *mountpoint;
665 parent = path->mnt->mnt_parent;
666 if (parent == path->mnt)
668 mountpoint = path->mnt->mnt_mountpoint;
669 path->dentry = mountpoint;
674 int follow_up(struct path *path)
676 struct vfsmount *parent;
677 struct dentry *mountpoint;
679 br_read_lock(vfsmount_lock);
680 parent = path->mnt->mnt_parent;
681 if (parent == path->mnt) {
682 br_read_unlock(vfsmount_lock);
686 mountpoint = dget(path->mnt->mnt_mountpoint);
687 br_read_unlock(vfsmount_lock);
689 path->dentry = mountpoint;
696 * Perform an automount
697 * - return -EISDIR to tell follow_managed() to stop and return the path we
700 static int follow_automount(struct path *path, unsigned flags,
703 struct vfsmount *mnt;
706 if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
709 /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT
710 * and this is the terminal part of the path.
712 if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_PARENT))
713 return -EISDIR; /* we actually want to stop here */
715 /* We want to mount if someone is trying to open/create a file of any
716 * type under the mountpoint, wants to traverse through the mountpoint
717 * or wants to open the mounted directory.
719 * We don't want to mount if someone's just doing a stat and they've
720 * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and
721 * appended a '/' to the name.
723 if (!(flags & LOOKUP_FOLLOW) &&
724 !(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
725 LOOKUP_OPEN | LOOKUP_CREATE)))
728 current->total_link_count++;
729 if (current->total_link_count >= 40)
732 mnt = path->dentry->d_op->d_automount(path);
735 * The filesystem is allowed to return -EISDIR here to indicate
736 * it doesn't want to automount. For instance, autofs would do
737 * this so that its userspace daemon can mount on this dentry.
739 * However, we can only permit this if it's a terminal point in
740 * the path being looked up; if it wasn't then the remainder of
741 * the path is inaccessible and we should say so.
743 if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT))
748 if (!mnt) /* mount collision */
752 /* lock_mount() may release path->mnt on error */
756 err = finish_automount(mnt, path);
760 /* Someone else made a mount here whilst we were busy */
765 path->dentry = dget(mnt->mnt_root);
774 * Handle a dentry that is managed in some way.
775 * - Flagged for transit management (autofs)
776 * - Flagged as mountpoint
777 * - Flagged as automount point
779 * This may only be called in refwalk mode.
781 * Serialization is taken care of in namespace.c
783 static int follow_managed(struct path *path, unsigned flags)
785 struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
787 bool need_mntput = false;
790 /* Given that we're not holding a lock here, we retain the value in a
791 * local variable for each dentry as we look at it so that we don't see
792 * the components of that value change under us */
793 while (managed = ACCESS_ONCE(path->dentry->d_flags),
794 managed &= DCACHE_MANAGED_DENTRY,
795 unlikely(managed != 0)) {
796 /* Allow the filesystem to manage the transit without i_mutex
798 if (managed & DCACHE_MANAGE_TRANSIT) {
799 BUG_ON(!path->dentry->d_op);
800 BUG_ON(!path->dentry->d_op->d_manage);
801 ret = path->dentry->d_op->d_manage(path->dentry, false);
806 /* Transit to a mounted filesystem. */
807 if (managed & DCACHE_MOUNTED) {
808 struct vfsmount *mounted = lookup_mnt(path);
814 path->dentry = dget(mounted->mnt_root);
819 /* Something is mounted on this dentry in another
820 * namespace and/or whatever was mounted there in this
821 * namespace got unmounted before we managed to get the
825 /* Handle an automount point */
826 if (managed & DCACHE_NEED_AUTOMOUNT) {
827 ret = follow_automount(path, flags, &need_mntput);
833 /* We didn't change the current path point */
837 if (need_mntput && path->mnt == mnt)
844 int follow_down_one(struct path *path)
846 struct vfsmount *mounted;
848 mounted = lookup_mnt(path);
853 path->dentry = dget(mounted->mnt_root);
859 static inline bool managed_dentry_might_block(struct dentry *dentry)
861 return (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
862 dentry->d_op->d_manage(dentry, true) < 0);
866 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
867 * we meet a managed dentry that would need blocking.
869 static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
870 struct inode **inode)
873 struct vfsmount *mounted;
875 * Don't forget we might have a non-mountpoint managed dentry
876 * that wants to block transit.
878 if (unlikely(managed_dentry_might_block(path->dentry)))
881 if (!d_mountpoint(path->dentry))
884 mounted = __lookup_mnt(path->mnt, path->dentry, 1);
888 path->dentry = mounted->mnt_root;
889 nd->seq = read_seqcount_begin(&path->dentry->d_seq);
891 * Update the inode too. We don't need to re-check the
892 * dentry sequence number here after this d_inode read,
893 * because a mount-point is always pinned.
895 *inode = path->dentry->d_inode;
900 static void follow_mount_rcu(struct nameidata *nd)
902 while (d_mountpoint(nd->path.dentry)) {
903 struct vfsmount *mounted;
904 mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
907 nd->path.mnt = mounted;
908 nd->path.dentry = mounted->mnt_root;
909 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
913 static int follow_dotdot_rcu(struct nameidata *nd)
918 if (nd->path.dentry == nd->root.dentry &&
919 nd->path.mnt == nd->root.mnt) {
922 if (nd->path.dentry != nd->path.mnt->mnt_root) {
923 struct dentry *old = nd->path.dentry;
924 struct dentry *parent = old->d_parent;
927 seq = read_seqcount_begin(&parent->d_seq);
928 if (read_seqcount_retry(&old->d_seq, nd->seq))
930 nd->path.dentry = parent;
934 if (!follow_up_rcu(&nd->path))
936 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
938 follow_mount_rcu(nd);
939 nd->inode = nd->path.dentry->d_inode;
943 nd->flags &= ~LOOKUP_RCU;
944 if (!(nd->flags & LOOKUP_ROOT))
947 br_read_unlock(vfsmount_lock);
952 * Follow down to the covering mount currently visible to userspace. At each
953 * point, the filesystem owning that dentry may be queried as to whether the
954 * caller is permitted to proceed or not.
956 int follow_down(struct path *path)
961 while (managed = ACCESS_ONCE(path->dentry->d_flags),
962 unlikely(managed & DCACHE_MANAGED_DENTRY)) {
963 /* Allow the filesystem to manage the transit without i_mutex
966 * We indicate to the filesystem if someone is trying to mount
967 * something here. This gives autofs the chance to deny anyone
968 * other than its daemon the right to mount on its
971 * The filesystem may sleep at this point.
973 if (managed & DCACHE_MANAGE_TRANSIT) {
974 BUG_ON(!path->dentry->d_op);
975 BUG_ON(!path->dentry->d_op->d_manage);
976 ret = path->dentry->d_op->d_manage(
977 path->dentry, false);
979 return ret == -EISDIR ? 0 : ret;
982 /* Transit to a mounted filesystem. */
983 if (managed & DCACHE_MOUNTED) {
984 struct vfsmount *mounted = lookup_mnt(path);
990 path->dentry = dget(mounted->mnt_root);
994 /* Don't handle automount points here */
1001 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1003 static void follow_mount(struct path *path)
1005 while (d_mountpoint(path->dentry)) {
1006 struct vfsmount *mounted = lookup_mnt(path);
1011 path->mnt = mounted;
1012 path->dentry = dget(mounted->mnt_root);
1016 static void follow_dotdot(struct nameidata *nd)
1021 struct dentry *old = nd->path.dentry;
1023 if (nd->path.dentry == nd->root.dentry &&
1024 nd->path.mnt == nd->root.mnt) {
1027 if (nd->path.dentry != nd->path.mnt->mnt_root) {
1028 /* rare case of legitimate dget_parent()... */
1029 nd->path.dentry = dget_parent(nd->path.dentry);
1033 if (!follow_up(&nd->path))
1036 follow_mount(&nd->path);
1037 nd->inode = nd->path.dentry->d_inode;
1041 * Allocate a dentry with name and parent, and perform a parent
1042 * directory ->lookup on it. Returns the new dentry, or ERR_PTR
1043 * on error. parent->d_inode->i_mutex must be held. d_lookup must
1044 * have verified that no child exists while under i_mutex.
1046 static struct dentry *d_alloc_and_lookup(struct dentry *parent,
1047 struct qstr *name, struct nameidata *nd)
1049 struct inode *inode = parent->d_inode;
1050 struct dentry *dentry;
1053 /* Don't create child dentry for a dead directory. */
1054 if (unlikely(IS_DEADDIR(inode)))
1055 return ERR_PTR(-ENOENT);
1057 dentry = d_alloc(parent, name);
1058 if (unlikely(!dentry))
1059 return ERR_PTR(-ENOMEM);
1061 old = inode->i_op->lookup(inode, dentry, nd);
1062 if (unlikely(old)) {
1070 * We already have a dentry, but require a lookup to be performed on the parent
1071 * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error.
1072 * parent->d_inode->i_mutex must be held. d_lookup must have verified that no
1073 * child exists while under i_mutex.
1075 static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry,
1076 struct nameidata *nd)
1078 struct inode *inode = parent->d_inode;
1081 /* Don't create child dentry for a dead directory. */
1082 if (unlikely(IS_DEADDIR(inode)))
1083 return ERR_PTR(-ENOENT);
1085 old = inode->i_op->lookup(inode, dentry, nd);
1086 if (unlikely(old)) {
1094 * It's more convoluted than I'd like it to be, but... it's still fairly
1095 * small and for now I'd prefer to have fast path as straight as possible.
1096 * It _is_ time-critical.
1098 static int do_lookup(struct nameidata *nd, struct qstr *name,
1099 struct path *path, struct inode **inode)
1101 struct vfsmount *mnt = nd->path.mnt;
1102 struct dentry *dentry, *parent = nd->path.dentry;
1108 * Rename seqlock is not required here because in the off chance
1109 * of a false negative due to a concurrent rename, we're going to
1110 * do the non-racy lookup, below.
1112 if (nd->flags & LOOKUP_RCU) {
1115 dentry = __d_lookup_rcu(parent, name, &seq, inode);
1119 /* Memory barrier in read_seqcount_begin of child is enough */
1120 if (__read_seqcount_retry(&parent->d_seq, nd->seq))
1124 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
1125 status = d_revalidate(dentry, nd);
1126 if (unlikely(status <= 0)) {
1127 if (status != -ECHILD)
1132 if (unlikely(d_need_lookup(dentry)))
1135 path->dentry = dentry;
1136 if (unlikely(!__follow_mount_rcu(nd, path, inode)))
1138 if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
1142 if (unlazy_walk(nd, dentry))
1145 dentry = __d_lookup(parent, name);
1148 if (dentry && unlikely(d_need_lookup(dentry))) {
1153 if (unlikely(!dentry)) {
1154 struct inode *dir = parent->d_inode;
1155 BUG_ON(nd->inode != dir);
1157 mutex_lock(&dir->i_mutex);
1158 dentry = d_lookup(parent, name);
1159 if (likely(!dentry)) {
1160 dentry = d_alloc_and_lookup(parent, name, nd);
1161 if (IS_ERR(dentry)) {
1162 mutex_unlock(&dir->i_mutex);
1163 return PTR_ERR(dentry);
1168 } else if (unlikely(d_need_lookup(dentry))) {
1169 dentry = d_inode_lookup(parent, dentry, nd);
1170 if (IS_ERR(dentry)) {
1171 mutex_unlock(&dir->i_mutex);
1172 return PTR_ERR(dentry);
1178 mutex_unlock(&dir->i_mutex);
1180 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
1181 status = d_revalidate(dentry, nd);
1182 if (unlikely(status <= 0)) {
1187 if (!d_invalidate(dentry)) {
1196 path->dentry = dentry;
1197 err = follow_managed(path, nd->flags);
1198 if (unlikely(err < 0)) {
1199 path_put_conditional(path, nd);
1202 *inode = path->dentry->d_inode;
1206 static inline int may_lookup(struct nameidata *nd)
1208 if (nd->flags & LOOKUP_RCU) {
1209 int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
1212 if (unlazy_walk(nd, NULL))
1215 return inode_permission(nd->inode, MAY_EXEC);
1218 static inline int handle_dots(struct nameidata *nd, int type)
1220 if (type == LAST_DOTDOT) {
1221 if (nd->flags & LOOKUP_RCU) {
1222 if (follow_dotdot_rcu(nd))
1230 static void terminate_walk(struct nameidata *nd)
1232 if (!(nd->flags & LOOKUP_RCU)) {
1233 path_put(&nd->path);
1235 nd->flags &= ~LOOKUP_RCU;
1236 if (!(nd->flags & LOOKUP_ROOT))
1237 nd->root.mnt = NULL;
1239 br_read_unlock(vfsmount_lock);
1243 static inline int walk_component(struct nameidata *nd, struct path *path,
1244 struct qstr *name, int type, int follow)
1246 struct inode *inode;
1249 * "." and ".." are special - ".." especially so because it has
1250 * to be able to know about the current root directory and
1251 * parent relationships.
1253 if (unlikely(type != LAST_NORM))
1254 return handle_dots(nd, type);
1255 err = do_lookup(nd, name, path, &inode);
1256 if (unlikely(err)) {
1261 path_to_nameidata(path, nd);
1265 if (unlikely(inode->i_op->follow_link) && follow) {
1266 if (nd->flags & LOOKUP_RCU) {
1267 if (unlikely(unlazy_walk(nd, path->dentry))) {
1272 BUG_ON(inode != path->dentry->d_inode);
1275 path_to_nameidata(path, nd);
1281 * This limits recursive symlink follows to 8, while
1282 * limiting consecutive symlinks to 40.
1284 * Without that kind of total limit, nasty chains of consecutive
1285 * symlinks can cause almost arbitrarily long lookups.
1287 static inline int nested_symlink(struct path *path, struct nameidata *nd)
1291 if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
1292 path_put_conditional(path, nd);
1293 path_put(&nd->path);
1296 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
1299 current->link_count++;
1302 struct path link = *path;
1305 res = follow_link(&link, nd, &cookie);
1307 res = walk_component(nd, path, &nd->last,
1308 nd->last_type, LOOKUP_FOLLOW);
1309 put_link(nd, &link, cookie);
1312 current->link_count--;
1319 * This is the basic name resolution function, turning a pathname into
1320 * the final dentry. We expect 'base' to be positive and a directory.
1322 * Returns 0 and nd will have valid dentry and mnt on success.
1323 * Returns error and drops reference to input namei data on failure.
1325 static int link_path_walk(const char *name, struct nameidata *nd)
1335 /* At this point we know we have a real path component. */
1342 err = may_lookup(nd);
1347 c = *(const unsigned char *)name;
1349 hash = init_name_hash();
1352 hash = partial_name_hash(c, hash);
1353 c = *(const unsigned char *)name;
1354 } while (c && (c != '/'));
1355 this.len = name - (const char *) this.name;
1356 this.hash = end_name_hash(hash);
1359 if (this.name[0] == '.') switch (this.len) {
1361 if (this.name[1] == '.') {
1363 nd->flags |= LOOKUP_JUMPED;
1369 if (likely(type == LAST_NORM)) {
1370 struct dentry *parent = nd->path.dentry;
1371 nd->flags &= ~LOOKUP_JUMPED;
1372 if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
1373 err = parent->d_op->d_hash(parent, nd->inode,
1380 /* remove trailing slashes? */
1382 goto last_component;
1383 while (*++name == '/');
1385 goto last_component;
1387 err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW);
1392 err = nested_symlink(&next, nd);
1397 if (!nd->inode->i_op->lookup)
1400 /* here ends the main loop */
1404 nd->last_type = type;
1411 static int path_init(int dfd, const char *name, unsigned int flags,
1412 struct nameidata *nd, struct file **fp)
1418 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1419 nd->flags = flags | LOOKUP_JUMPED;
1421 if (flags & LOOKUP_ROOT) {
1422 struct inode *inode = nd->root.dentry->d_inode;
1424 if (!inode->i_op->lookup)
1426 retval = inode_permission(inode, MAY_EXEC);
1430 nd->path = nd->root;
1432 if (flags & LOOKUP_RCU) {
1433 br_read_lock(vfsmount_lock);
1435 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1437 path_get(&nd->path);
1442 nd->root.mnt = NULL;
1445 if (flags & LOOKUP_RCU) {
1446 br_read_lock(vfsmount_lock);
1451 path_get(&nd->root);
1453 nd->path = nd->root;
1454 } else if (dfd == AT_FDCWD) {
1455 if (flags & LOOKUP_RCU) {
1456 struct fs_struct *fs = current->fs;
1459 br_read_lock(vfsmount_lock);
1463 seq = read_seqcount_begin(&fs->seq);
1465 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1466 } while (read_seqcount_retry(&fs->seq, seq));
1468 get_fs_pwd(current->fs, &nd->path);
1471 struct dentry *dentry;
1473 file = fget_raw_light(dfd, &fput_needed);
1478 dentry = file->f_path.dentry;
1482 if (!S_ISDIR(dentry->d_inode->i_mode))
1485 retval = inode_permission(dentry->d_inode, MAY_EXEC);
1490 nd->path = file->f_path;
1491 if (flags & LOOKUP_RCU) {
1494 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1495 br_read_lock(vfsmount_lock);
1498 path_get(&file->f_path);
1499 fput_light(file, fput_needed);
1503 nd->inode = nd->path.dentry->d_inode;
1507 fput_light(file, fput_needed);
1512 static inline int lookup_last(struct nameidata *nd, struct path *path)
1514 if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
1515 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
1517 nd->flags &= ~LOOKUP_PARENT;
1518 return walk_component(nd, path, &nd->last, nd->last_type,
1519 nd->flags & LOOKUP_FOLLOW);
1522 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1523 static int path_lookupat(int dfd, const char *name,
1524 unsigned int flags, struct nameidata *nd)
1526 struct file *base = NULL;
1531 * Path walking is largely split up into 2 different synchronisation
1532 * schemes, rcu-walk and ref-walk (explained in
1533 * Documentation/filesystems/path-lookup.txt). These share much of the
1534 * path walk code, but some things particularly setup, cleanup, and
1535 * following mounts are sufficiently divergent that functions are
1536 * duplicated. Typically there is a function foo(), and its RCU
1537 * analogue, foo_rcu().
1539 * -ECHILD is the error number of choice (just to avoid clashes) that
1540 * is returned if some aspect of an rcu-walk fails. Such an error must
1541 * be handled by restarting a traditional ref-walk (which will always
1542 * be able to complete).
1544 err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);
1549 current->total_link_count = 0;
1550 err = link_path_walk(name, nd);
1552 if (!err && !(flags & LOOKUP_PARENT)) {
1553 err = lookup_last(nd, &path);
1556 struct path link = path;
1557 nd->flags |= LOOKUP_PARENT;
1558 err = follow_link(&link, nd, &cookie);
1560 err = lookup_last(nd, &path);
1561 put_link(nd, &link, cookie);
1566 err = complete_walk(nd);
1568 if (!err && nd->flags & LOOKUP_DIRECTORY) {
1569 if (!nd->inode->i_op->lookup) {
1570 path_put(&nd->path);
1578 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
1579 path_put(&nd->root);
1580 nd->root.mnt = NULL;
1585 static int do_path_lookup(int dfd, const char *name,
1586 unsigned int flags, struct nameidata *nd)
1588 int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd);
1589 if (unlikely(retval == -ECHILD))
1590 retval = path_lookupat(dfd, name, flags, nd);
1591 if (unlikely(retval == -ESTALE))
1592 retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd);
1594 if (likely(!retval)) {
1595 if (unlikely(!audit_dummy_context())) {
1596 if (nd->path.dentry && nd->inode)
1597 audit_inode(name, nd->path.dentry);
1603 int kern_path_parent(const char *name, struct nameidata *nd)
1605 return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd);
1608 int kern_path(const char *name, unsigned int flags, struct path *path)
1610 struct nameidata nd;
1611 int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
1618 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1619 * @dentry: pointer to dentry of the base directory
1620 * @mnt: pointer to vfs mount of the base directory
1621 * @name: pointer to file name
1622 * @flags: lookup flags
1623 * @path: pointer to struct path to fill
1625 int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
1626 const char *name, unsigned int flags,
1629 struct nameidata nd;
1631 nd.root.dentry = dentry;
1633 BUG_ON(flags & LOOKUP_PARENT);
1634 /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
1635 err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd);
1641 static struct dentry *__lookup_hash(struct qstr *name,
1642 struct dentry *base, struct nameidata *nd)
1644 struct inode *inode = base->d_inode;
1645 struct dentry *dentry;
1648 err = inode_permission(inode, MAY_EXEC);
1650 return ERR_PTR(err);
1653 * Don't bother with __d_lookup: callers are for creat as
1654 * well as unlink, so a lot of the time it would cost
1657 dentry = d_lookup(base, name);
1659 if (dentry && d_need_lookup(dentry)) {
1661 * __lookup_hash is called with the parent dir's i_mutex already
1662 * held, so we are good to go here.
1664 dentry = d_inode_lookup(base, dentry, nd);
1669 if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) {
1670 int status = d_revalidate(dentry, nd);
1671 if (unlikely(status <= 0)) {
1673 * The dentry failed validation.
1674 * If d_revalidate returned 0 attempt to invalidate
1675 * the dentry otherwise d_revalidate is asking us
1676 * to return a fail status.
1680 return ERR_PTR(status);
1681 } else if (!d_invalidate(dentry)) {
1689 dentry = d_alloc_and_lookup(base, name, nd);
1695 * Restricted form of lookup. Doesn't follow links, single-component only,
1696 * needs parent already locked. Doesn't follow mounts.
1699 static struct dentry *lookup_hash(struct nameidata *nd)
1701 return __lookup_hash(&nd->last, nd->path.dentry, nd);
1705 * lookup_one_len - filesystem helper to lookup single pathname component
1706 * @name: pathname component to lookup
1707 * @base: base directory to lookup from
1708 * @len: maximum length @len should be interpreted to
1710 * Note that this routine is purely a helper for filesystem usage and should
1711 * not be called by generic code. Also note that by using this function the
1712 * nameidata argument is passed to the filesystem methods and a filesystem
1713 * using this helper needs to be prepared for that.
1715 struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
1721 WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
1726 return ERR_PTR(-EACCES);
1728 hash = init_name_hash();
1730 c = *(const unsigned char *)name++;
1731 if (c == '/' || c == '\0')
1732 return ERR_PTR(-EACCES);
1733 hash = partial_name_hash(c, hash);
1735 this.hash = end_name_hash(hash);
1737 * See if the low-level filesystem might want
1738 * to use its own hash..
1740 if (base->d_flags & DCACHE_OP_HASH) {
1741 int err = base->d_op->d_hash(base, base->d_inode, &this);
1743 return ERR_PTR(err);
1746 return __lookup_hash(&this, base, NULL);
1749 int user_path_at(int dfd, const char __user *name, unsigned flags,
1752 struct nameidata nd;
1753 char *tmp = getname_flags(name, flags);
1754 int err = PTR_ERR(tmp);
1757 BUG_ON(flags & LOOKUP_PARENT);
1759 err = do_path_lookup(dfd, tmp, flags, &nd);
1767 static int user_path_parent(int dfd, const char __user *path,
1768 struct nameidata *nd, char **name)
1770 char *s = getname(path);
1776 error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
1786 * It's inline, so penalty for filesystems that don't use sticky bit is
1789 static inline int check_sticky(struct inode *dir, struct inode *inode)
1791 uid_t fsuid = current_fsuid();
1793 if (!(dir->i_mode & S_ISVTX))
1795 if (current_user_ns() != inode_userns(inode))
1797 if (inode->i_uid == fsuid)
1799 if (dir->i_uid == fsuid)
1803 return !ns_capable(inode_userns(inode), CAP_FOWNER);
1807 * Check whether we can remove a link victim from directory dir, check
1808 * whether the type of victim is right.
1809 * 1. We can't do it if dir is read-only (done in permission())
1810 * 2. We should have write and exec permissions on dir
1811 * 3. We can't remove anything from append-only dir
1812 * 4. We can't do anything with immutable dir (done in permission())
1813 * 5. If the sticky bit on dir is set we should either
1814 * a. be owner of dir, or
1815 * b. be owner of victim, or
1816 * c. have CAP_FOWNER capability
1817 * 6. If the victim is append-only or immutable we can't do antyhing with
1818 * links pointing to it.
1819 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1820 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1821 * 9. We can't remove a root or mountpoint.
1822 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1823 * nfs_async_unlink().
1825 static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1829 if (!victim->d_inode)
1832 BUG_ON(victim->d_parent->d_inode != dir);
1833 audit_inode_child(victim, dir);
1835 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
1840 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1841 IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
1844 if (!S_ISDIR(victim->d_inode->i_mode))
1846 if (IS_ROOT(victim))
1848 } else if (S_ISDIR(victim->d_inode->i_mode))
1850 if (IS_DEADDIR(dir))
1852 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1857 /* Check whether we can create an object with dentry child in directory
1859 * 1. We can't do it if child already exists (open has special treatment for
1860 * this case, but since we are inlined it's OK)
1861 * 2. We can't do it if dir is read-only (done in permission())
1862 * 3. We should have write and exec permissions on dir
1863 * 4. We can't do it if dir is immutable (done in permission())
1865 static inline int may_create(struct inode *dir, struct dentry *child)
1869 if (IS_DEADDIR(dir))
1871 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
1875 * p1 and p2 should be directories on the same fs.
1877 struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1882 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1886 mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1888 p = d_ancestor(p2, p1);
1890 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
1891 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
1895 p = d_ancestor(p1, p2);
1897 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1898 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1902 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1903 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1907 void unlock_rename(struct dentry *p1, struct dentry *p2)
1909 mutex_unlock(&p1->d_inode->i_mutex);
1911 mutex_unlock(&p2->d_inode->i_mutex);
1912 mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1916 int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1917 struct nameidata *nd)
1919 int error = may_create(dir, dentry);
1924 if (!dir->i_op->create)
1925 return -EACCES; /* shouldn't it be ENOSYS? */
1928 error = security_inode_create(dir, dentry, mode);
1931 error = dir->i_op->create(dir, dentry, mode, nd);
1933 fsnotify_create(dir, dentry);
1937 static int may_open(struct path *path, int acc_mode, int flag)
1939 struct dentry *dentry = path->dentry;
1940 struct inode *inode = dentry->d_inode;
1950 switch (inode->i_mode & S_IFMT) {
1954 if (acc_mode & MAY_WRITE)
1959 if (path->mnt->mnt_flags & MNT_NODEV)
1968 error = inode_permission(inode, acc_mode);
1973 * An append-only file must be opened in append mode for writing.
1975 if (IS_APPEND(inode)) {
1976 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
1982 /* O_NOATIME can only be set by the owner or superuser */
1983 if (flag & O_NOATIME && !inode_owner_or_capable(inode))
1987 * Ensure there are no outstanding leases on the file.
1989 return break_lease(inode, flag);
1992 static int handle_truncate(struct file *filp)
1994 struct path *path = &filp->f_path;
1995 struct inode *inode = path->dentry->d_inode;
1996 int error = get_write_access(inode);
2000 * Refuse to truncate files with mandatory locks held on them.
2002 error = locks_verify_locked(inode);
2004 error = security_path_truncate(path);
2006 error = do_truncate(path->dentry, 0,
2007 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
2010 put_write_access(inode);
2014 static inline int open_to_namei_flags(int flag)
2016 if ((flag & O_ACCMODE) == 3)
2022 * Handle the last step of open()
2024 static struct file *do_last(struct nameidata *nd, struct path *path,
2025 const struct open_flags *op, const char *pathname)
2027 struct dentry *dir = nd->path.dentry;
2028 struct dentry *dentry;
2029 int open_flag = op->open_flag;
2030 int will_truncate = open_flag & O_TRUNC;
2032 int acc_mode = op->acc_mode;
2036 nd->flags &= ~LOOKUP_PARENT;
2037 nd->flags |= op->intent;
2039 switch (nd->last_type) {
2042 error = handle_dots(nd, nd->last_type);
2044 return ERR_PTR(error);
2047 error = complete_walk(nd);
2049 return ERR_PTR(error);
2050 audit_inode(pathname, nd->path.dentry);
2051 if (open_flag & O_CREAT) {
2057 error = complete_walk(nd);
2059 return ERR_PTR(error);
2060 audit_inode(pathname, dir);
2064 if (!(open_flag & O_CREAT)) {
2066 if (nd->last.name[nd->last.len])
2067 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
2068 if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
2070 /* we _can_ be in RCU mode here */
2071 error = walk_component(nd, path, &nd->last, LAST_NORM,
2074 return ERR_PTR(error);
2075 if (error) /* symlink */
2078 error = complete_walk(nd);
2080 return ERR_PTR(-ECHILD);
2083 if (nd->flags & LOOKUP_DIRECTORY) {
2084 if (!nd->inode->i_op->lookup)
2087 audit_inode(pathname, nd->path.dentry);
2091 /* create side of things */
2092 error = complete_walk(nd);
2094 return ERR_PTR(error);
2096 audit_inode(pathname, dir);
2098 /* trailing slashes? */
2099 if (nd->last.name[nd->last.len])
2102 mutex_lock(&dir->d_inode->i_mutex);
2104 dentry = lookup_hash(nd);
2105 error = PTR_ERR(dentry);
2106 if (IS_ERR(dentry)) {
2107 mutex_unlock(&dir->d_inode->i_mutex);
2111 path->dentry = dentry;
2112 path->mnt = nd->path.mnt;
2114 /* Negative dentry, just create the file */
2115 if (!dentry->d_inode) {
2116 int mode = op->mode;
2117 if (!IS_POSIXACL(dir->d_inode))
2118 mode &= ~current_umask();
2120 * This write is needed to ensure that a
2121 * rw->ro transition does not occur between
2122 * the time when the file is created and when
2123 * a permanent write count is taken through
2124 * the 'struct file' in nameidata_to_filp().
2126 error = mnt_want_write(nd->path.mnt);
2128 goto exit_mutex_unlock;
2130 /* Don't check for write permission, don't truncate */
2131 open_flag &= ~O_TRUNC;
2133 acc_mode = MAY_OPEN;
2134 error = security_path_mknod(&nd->path, dentry, mode, 0);
2136 goto exit_mutex_unlock;
2137 error = vfs_create(dir->d_inode, dentry, mode, nd);
2139 goto exit_mutex_unlock;
2140 mutex_unlock(&dir->d_inode->i_mutex);
2141 dput(nd->path.dentry);
2142 nd->path.dentry = dentry;
2147 * It already exists.
2149 mutex_unlock(&dir->d_inode->i_mutex);
2150 audit_inode(pathname, path->dentry);
2153 if (open_flag & O_EXCL)
2156 error = follow_managed(path, nd->flags);
2161 if (!path->dentry->d_inode)
2164 if (path->dentry->d_inode->i_op->follow_link)
2167 path_to_nameidata(path, nd);
2168 nd->inode = path->dentry->d_inode;
2170 if (S_ISDIR(nd->inode->i_mode))
2173 if (!S_ISREG(nd->inode->i_mode))
2176 if (will_truncate) {
2177 error = mnt_want_write(nd->path.mnt);
2183 error = may_open(&nd->path, acc_mode, open_flag);
2186 filp = nameidata_to_filp(nd);
2187 if (!IS_ERR(filp)) {
2188 error = ima_file_check(filp, op->acc_mode);
2191 filp = ERR_PTR(error);
2194 if (!IS_ERR(filp)) {
2195 if (will_truncate) {
2196 error = handle_truncate(filp);
2199 filp = ERR_PTR(error);
2205 mnt_drop_write(nd->path.mnt);
2206 path_put(&nd->path);
2210 mutex_unlock(&dir->d_inode->i_mutex);
2212 path_put_conditional(path, nd);
2214 filp = ERR_PTR(error);
2218 static struct file *path_openat(int dfd, const char *pathname,
2219 struct nameidata *nd, const struct open_flags *op, int flags)
2221 struct file *base = NULL;
2226 filp = get_empty_filp();
2228 return ERR_PTR(-ENFILE);
2230 filp->f_flags = op->open_flag;
2231 nd->intent.open.file = filp;
2232 nd->intent.open.flags = open_to_namei_flags(op->open_flag);
2233 nd->intent.open.create_mode = op->mode;
2235 error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
2236 if (unlikely(error))
2239 current->total_link_count = 0;
2240 error = link_path_walk(pathname, nd);
2241 if (unlikely(error))
2244 filp = do_last(nd, &path, op, pathname);
2245 while (unlikely(!filp)) { /* trailing symlink */
2246 struct path link = path;
2248 if (!(nd->flags & LOOKUP_FOLLOW)) {
2249 path_put_conditional(&path, nd);
2250 path_put(&nd->path);
2251 filp = ERR_PTR(-ELOOP);
2254 nd->flags |= LOOKUP_PARENT;
2255 nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
2256 error = follow_link(&link, nd, &cookie);
2257 if (unlikely(error))
2258 filp = ERR_PTR(error);
2260 filp = do_last(nd, &path, op, pathname);
2261 put_link(nd, &link, cookie);
2264 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))
2265 path_put(&nd->root);
2268 release_open_intent(nd);
2272 filp = ERR_PTR(error);
2276 struct file *do_filp_open(int dfd, const char *pathname,
2277 const struct open_flags *op, int flags)
2279 struct nameidata nd;
2282 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
2283 if (unlikely(filp == ERR_PTR(-ECHILD)))
2284 filp = path_openat(dfd, pathname, &nd, op, flags);
2285 if (unlikely(filp == ERR_PTR(-ESTALE)))
2286 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL);
2290 struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
2291 const char *name, const struct open_flags *op, int flags)
2293 struct nameidata nd;
2297 nd.root.dentry = dentry;
2299 flags |= LOOKUP_ROOT;
2301 if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
2302 return ERR_PTR(-ELOOP);
2304 file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU);
2305 if (unlikely(file == ERR_PTR(-ECHILD)))
2306 file = path_openat(-1, name, &nd, op, flags);
2307 if (unlikely(file == ERR_PTR(-ESTALE)))
2308 file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL);
2312 struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
2314 struct dentry *dentry = ERR_PTR(-EEXIST);
2315 struct nameidata nd;
2316 int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
2318 return ERR_PTR(error);
2321 * Yucky last component or no last component at all?
2322 * (foo/., foo/.., /////)
2324 if (nd.last_type != LAST_NORM)
2326 nd.flags &= ~LOOKUP_PARENT;
2327 nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL;
2328 nd.intent.open.flags = O_EXCL;
2331 * Do the final lookup.
2333 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2334 dentry = lookup_hash(&nd);
2338 if (dentry->d_inode)
2341 * Special case - lookup gave negative, but... we had foo/bar/
2342 * From the vfs_mknod() POV we just have a negative dentry -
2343 * all is fine. Let's be bastards - you had / on the end, you've
2344 * been asking for (non-existent) directory. -ENOENT for you.
2346 if (unlikely(!is_dir && nd.last.name[nd.last.len])) {
2348 dentry = ERR_PTR(-ENOENT);
2355 dentry = ERR_PTR(-EEXIST);
2357 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2362 EXPORT_SYMBOL(kern_path_create);
2364 struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
2366 char *tmp = getname(pathname);
2369 return ERR_CAST(tmp);
2370 res = kern_path_create(dfd, tmp, path, is_dir);
2374 EXPORT_SYMBOL(user_path_create);
2376 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
2378 int error = may_create(dir, dentry);
2383 if ((S_ISCHR(mode) || S_ISBLK(mode)) &&
2384 !ns_capable(inode_userns(dir), CAP_MKNOD))
2387 if (!dir->i_op->mknod)
2390 error = devcgroup_inode_mknod(mode, dev);
2394 error = security_inode_mknod(dir, dentry, mode, dev);
2398 error = dir->i_op->mknod(dir, dentry, mode, dev);
2400 fsnotify_create(dir, dentry);
2404 static int may_mknod(mode_t mode)
2406 switch (mode & S_IFMT) {
2412 case 0: /* zero mode translates to S_IFREG */
2421 SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
2424 struct dentry *dentry;
2431 dentry = user_path_create(dfd, filename, &path, 0);
2433 return PTR_ERR(dentry);
2435 if (!IS_POSIXACL(path.dentry->d_inode))
2436 mode &= ~current_umask();
2437 error = may_mknod(mode);
2440 error = mnt_want_write(path.mnt);
2443 error = security_path_mknod(&path, dentry, mode, dev);
2445 goto out_drop_write;
2446 switch (mode & S_IFMT) {
2447 case 0: case S_IFREG:
2448 error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
2450 case S_IFCHR: case S_IFBLK:
2451 error = vfs_mknod(path.dentry->d_inode,dentry,mode,
2452 new_decode_dev(dev));
2454 case S_IFIFO: case S_IFSOCK:
2455 error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
2459 mnt_drop_write(path.mnt);
2462 mutex_unlock(&path.dentry->d_inode->i_mutex);
2468 SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev)
2470 return sys_mknodat(AT_FDCWD, filename, mode, dev);
2473 int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
2475 int error = may_create(dir, dentry);
2480 if (!dir->i_op->mkdir)
2483 mode &= (S_IRWXUGO|S_ISVTX);
2484 error = security_inode_mkdir(dir, dentry, mode);
2488 error = dir->i_op->mkdir(dir, dentry, mode);
2490 fsnotify_mkdir(dir, dentry);
2494 SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode)
2496 struct dentry *dentry;
2500 dentry = user_path_create(dfd, pathname, &path, 1);
2502 return PTR_ERR(dentry);
2504 if (!IS_POSIXACL(path.dentry->d_inode))
2505 mode &= ~current_umask();
2506 error = mnt_want_write(path.mnt);
2509 error = security_path_mkdir(&path, dentry, mode);
2511 goto out_drop_write;
2512 error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
2514 mnt_drop_write(path.mnt);
2517 mutex_unlock(&path.dentry->d_inode->i_mutex);
2522 SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode)
2524 return sys_mkdirat(AT_FDCWD, pathname, mode);
2528 * The dentry_unhash() helper will try to drop the dentry early: we
2529 * should have a usage count of 2 if we're the only user of this
2530 * dentry, and if that is true (possibly after pruning the dcache),
2531 * then we drop the dentry now.
2533 * A low-level filesystem can, if it choses, legally
2536 * if (!d_unhashed(dentry))
2539 * if it cannot handle the case of removing a directory
2540 * that is still in use by something else..
2542 void dentry_unhash(struct dentry *dentry)
2544 shrink_dcache_parent(dentry);
2545 spin_lock(&dentry->d_lock);
2546 if (dentry->d_count == 1)
2548 spin_unlock(&dentry->d_lock);
2551 int vfs_rmdir(struct inode *dir, struct dentry *dentry)
2553 int error = may_delete(dir, dentry, 1);
2558 if (!dir->i_op->rmdir)
2561 mutex_lock(&dentry->d_inode->i_mutex);
2564 if (d_mountpoint(dentry))
2567 error = security_inode_rmdir(dir, dentry);
2571 shrink_dcache_parent(dentry);
2572 error = dir->i_op->rmdir(dir, dentry);
2576 dentry->d_inode->i_flags |= S_DEAD;
2580 mutex_unlock(&dentry->d_inode->i_mutex);
2586 static long do_rmdir(int dfd, const char __user *pathname)
2590 struct dentry *dentry;
2591 struct nameidata nd;
2593 error = user_path_parent(dfd, pathname, &nd, &name);
2597 switch(nd.last_type) {
2609 nd.flags &= ~LOOKUP_PARENT;
2611 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2612 dentry = lookup_hash(&nd);
2613 error = PTR_ERR(dentry);
2616 if (!dentry->d_inode) {
2620 error = mnt_want_write(nd.path.mnt);
2623 error = security_path_rmdir(&nd.path, dentry);
2626 error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
2628 mnt_drop_write(nd.path.mnt);
2632 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2639 SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
2641 return do_rmdir(AT_FDCWD, pathname);
2644 int vfs_unlink(struct inode *dir, struct dentry *dentry)
2646 int error = may_delete(dir, dentry, 0);
2651 if (!dir->i_op->unlink)
2654 mutex_lock(&dentry->d_inode->i_mutex);
2655 if (d_mountpoint(dentry))
2658 error = security_inode_unlink(dir, dentry);
2660 error = dir->i_op->unlink(dir, dentry);
2665 mutex_unlock(&dentry->d_inode->i_mutex);
2667 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2668 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
2669 fsnotify_link_count(dentry->d_inode);
2677 * Make sure that the actual truncation of the file will occur outside its
2678 * directory's i_mutex. Truncate can take a long time if there is a lot of
2679 * writeout happening, and we don't want to prevent access to the directory
2680 * while waiting on the I/O.
2682 static long do_unlinkat(int dfd, const char __user *pathname)
2686 struct dentry *dentry;
2687 struct nameidata nd;
2688 struct inode *inode = NULL;
2690 error = user_path_parent(dfd, pathname, &nd, &name);
2695 if (nd.last_type != LAST_NORM)
2698 nd.flags &= ~LOOKUP_PARENT;
2700 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2701 dentry = lookup_hash(&nd);
2702 error = PTR_ERR(dentry);
2703 if (!IS_ERR(dentry)) {
2704 /* Why not before? Because we want correct error value */
2705 if (nd.last.name[nd.last.len])
2707 inode = dentry->d_inode;
2711 error = mnt_want_write(nd.path.mnt);
2714 error = security_path_unlink(&nd.path, dentry);
2717 error = vfs_unlink(nd.path.dentry->d_inode, dentry);
2719 mnt_drop_write(nd.path.mnt);
2723 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2725 iput(inode); /* truncate the inode here */
2732 error = !dentry->d_inode ? -ENOENT :
2733 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2737 SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
2739 if ((flag & ~AT_REMOVEDIR) != 0)
2742 if (flag & AT_REMOVEDIR)
2743 return do_rmdir(dfd, pathname);
2745 return do_unlinkat(dfd, pathname);
2748 SYSCALL_DEFINE1(unlink, const char __user *, pathname)
2750 return do_unlinkat(AT_FDCWD, pathname);
2753 int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
2755 int error = may_create(dir, dentry);
2760 if (!dir->i_op->symlink)
2763 error = security_inode_symlink(dir, dentry, oldname);
2767 error = dir->i_op->symlink(dir, dentry, oldname);
2769 fsnotify_create(dir, dentry);
2773 SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
2774 int, newdfd, const char __user *, newname)
2778 struct dentry *dentry;
2781 from = getname(oldname);
2783 return PTR_ERR(from);
2785 dentry = user_path_create(newdfd, newname, &path, 0);
2786 error = PTR_ERR(dentry);
2790 error = mnt_want_write(path.mnt);
2793 error = security_path_symlink(&path, dentry, from);
2795 goto out_drop_write;
2796 error = vfs_symlink(path.dentry->d_inode, dentry, from);
2798 mnt_drop_write(path.mnt);
2801 mutex_unlock(&path.dentry->d_inode->i_mutex);
2808 SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
2810 return sys_symlinkat(oldname, AT_FDCWD, newname);
2813 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2815 struct inode *inode = old_dentry->d_inode;
2821 error = may_create(dir, new_dentry);
2825 if (dir->i_sb != inode->i_sb)
2829 * A link to an append-only or immutable file cannot be created.
2831 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2833 if (!dir->i_op->link)
2835 if (S_ISDIR(inode->i_mode))
2838 error = security_inode_link(old_dentry, dir, new_dentry);
2842 mutex_lock(&inode->i_mutex);
2843 /* Make sure we don't allow creating hardlink to an unlinked file */
2844 if (inode->i_nlink == 0)
2847 error = dir->i_op->link(old_dentry, dir, new_dentry);
2848 mutex_unlock(&inode->i_mutex);
2850 fsnotify_link(dir, inode, new_dentry);
2855 * Hardlinks are often used in delicate situations. We avoid
2856 * security-related surprises by not following symlinks on the
2859 * We don't follow them on the oldname either to be compatible
2860 * with linux 2.0, and to avoid hard-linking to directories
2861 * and other special files. --ADM
2863 SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
2864 int, newdfd, const char __user *, newname, int, flags)
2866 struct dentry *new_dentry;
2867 struct path old_path, new_path;
2871 if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
2874 * To use null names we require CAP_DAC_READ_SEARCH
2875 * This ensures that not everyone will be able to create
2876 * handlink using the passed filedescriptor.
2878 if (flags & AT_EMPTY_PATH) {
2879 if (!capable(CAP_DAC_READ_SEARCH))
2884 if (flags & AT_SYMLINK_FOLLOW)
2885 how |= LOOKUP_FOLLOW;
2887 error = user_path_at(olddfd, oldname, how, &old_path);
2891 new_dentry = user_path_create(newdfd, newname, &new_path, 0);
2892 error = PTR_ERR(new_dentry);
2893 if (IS_ERR(new_dentry))
2897 if (old_path.mnt != new_path.mnt)
2899 error = mnt_want_write(new_path.mnt);
2902 error = security_path_link(old_path.dentry, &new_path, new_dentry);
2904 goto out_drop_write;
2905 error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
2907 mnt_drop_write(new_path.mnt);
2910 mutex_unlock(&new_path.dentry->d_inode->i_mutex);
2911 path_put(&new_path);
2913 path_put(&old_path);
2918 SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
2920 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
2924 * The worst of all namespace operations - renaming directory. "Perverted"
2925 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2927 * a) we can get into loop creation. Check is done in is_subdir().
2928 * b) race potential - two innocent renames can create a loop together.
2929 * That's where 4.4 screws up. Current fix: serialization on
2930 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2932 * c) we have to lock _three_ objects - parents and victim (if it exists).
2933 * And that - after we got ->i_mutex on parents (until then we don't know
2934 * whether the target exists). Solution: try to be smart with locking
2935 * order for inodes. We rely on the fact that tree topology may change
2936 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2937 * move will be locked. Thus we can rank directories by the tree
2938 * (ancestors first) and rank all non-directories after them.
2939 * That works since everybody except rename does "lock parent, lookup,
2940 * lock child" and rename is under ->s_vfs_rename_mutex.
2941 * HOWEVER, it relies on the assumption that any object with ->lookup()
2942 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2943 * we'd better make sure that there's no link(2) for them.
2944 * d) conversion from fhandle to dentry may come in the wrong moment - when
2945 * we are removing the target. Solution: we will have to grab ->i_mutex
2946 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2947 * ->i_mutex on parents, which works but leads to some truly excessive
2950 static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2951 struct inode *new_dir, struct dentry *new_dentry)
2954 struct inode *target = new_dentry->d_inode;
2957 * If we are going to change the parent - check write permissions,
2958 * we'll need to flip '..'.
2960 if (new_dir != old_dir) {
2961 error = inode_permission(old_dentry->d_inode, MAY_WRITE);
2966 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2971 mutex_lock(&target->i_mutex);
2974 if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
2978 shrink_dcache_parent(new_dentry);
2979 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2984 target->i_flags |= S_DEAD;
2985 dont_mount(new_dentry);
2989 mutex_unlock(&target->i_mutex);
2991 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2992 d_move(old_dentry,new_dentry);
2996 static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2997 struct inode *new_dir, struct dentry *new_dentry)
2999 struct inode *target = new_dentry->d_inode;
3002 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
3008 mutex_lock(&target->i_mutex);
3011 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
3014 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
3019 dont_mount(new_dentry);
3020 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
3021 d_move(old_dentry, new_dentry);
3024 mutex_unlock(&target->i_mutex);
3029 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
3030 struct inode *new_dir, struct dentry *new_dentry)
3033 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
3034 const unsigned char *old_name;
3036 if (old_dentry->d_inode == new_dentry->d_inode)
3039 error = may_delete(old_dir, old_dentry, is_dir);
3043 if (!new_dentry->d_inode)
3044 error = may_create(new_dir, new_dentry);
3046 error = may_delete(new_dir, new_dentry, is_dir);
3050 if (!old_dir->i_op->rename)
3053 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
3056 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
3058 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
3060 fsnotify_move(old_dir, new_dir, old_name, is_dir,
3061 new_dentry->d_inode, old_dentry);
3062 fsnotify_oldname_free(old_name);
3067 SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
3068 int, newdfd, const char __user *, newname)
3070 struct dentry *old_dir, *new_dir;
3071 struct dentry *old_dentry, *new_dentry;
3072 struct dentry *trap;
3073 struct nameidata oldnd, newnd;
3078 error = user_path_parent(olddfd, oldname, &oldnd, &from);
3082 error = user_path_parent(newdfd, newname, &newnd, &to);
3087 if (oldnd.path.mnt != newnd.path.mnt)
3090 old_dir = oldnd.path.dentry;
3092 if (oldnd.last_type != LAST_NORM)
3095 new_dir = newnd.path.dentry;
3096 if (newnd.last_type != LAST_NORM)
3099 oldnd.flags &= ~LOOKUP_PARENT;
3100 newnd.flags &= ~LOOKUP_PARENT;
3101 newnd.flags |= LOOKUP_RENAME_TARGET;
3103 trap = lock_rename(new_dir, old_dir);
3105 old_dentry = lookup_hash(&oldnd);
3106 error = PTR_ERR(old_dentry);
3107 if (IS_ERR(old_dentry))
3109 /* source must exist */
3111 if (!old_dentry->d_inode)
3113 /* unless the source is a directory trailing slashes give -ENOTDIR */
3114 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
3116 if (oldnd.last.name[oldnd.last.len])
3118 if (newnd.last.name[newnd.last.len])
3121 /* source should not be ancestor of target */
3123 if (old_dentry == trap)
3125 new_dentry = lookup_hash(&newnd);
3126 error = PTR_ERR(new_dentry);
3127 if (IS_ERR(new_dentry))
3129 /* target should not be an ancestor of source */
3131 if (new_dentry == trap)
3134 error = mnt_want_write(oldnd.path.mnt);
3137 error = security_path_rename(&oldnd.path, old_dentry,
3138 &newnd.path, new_dentry);
3141 error = vfs_rename(old_dir->d_inode, old_dentry,
3142 new_dir->d_inode, new_dentry);
3144 mnt_drop_write(oldnd.path.mnt);
3150 unlock_rename(new_dir, old_dir);
3152 path_put(&newnd.path);
3155 path_put(&oldnd.path);
3161 SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
3163 return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
3166 int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
3170 len = PTR_ERR(link);
3175 if (len > (unsigned) buflen)
3177 if (copy_to_user(buffer, link, len))
3184 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
3185 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
3186 * using) it for any given inode is up to filesystem.
3188 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3190 struct nameidata nd;
3195 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
3197 return PTR_ERR(cookie);
3199 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
3200 if (dentry->d_inode->i_op->put_link)
3201 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
3205 int vfs_follow_link(struct nameidata *nd, const char *link)
3207 return __vfs_follow_link(nd, link);
3210 /* get the link contents into pagecache */
3211 static char *page_getlink(struct dentry * dentry, struct page **ppage)
3215 struct address_space *mapping = dentry->d_inode->i_mapping;
3216 page = read_mapping_page(mapping, 0, NULL);
3221 nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
3225 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3227 struct page *page = NULL;
3228 char *s = page_getlink(dentry, &page);
3229 int res = vfs_readlink(dentry,buffer,buflen,s);
3232 page_cache_release(page);
3237 void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
3239 struct page *page = NULL;
3240 nd_set_link(nd, page_getlink(dentry, &page));
3244 void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
3246 struct page *page = cookie;
3250 page_cache_release(page);
3255 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
3257 int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
3259 struct address_space *mapping = inode->i_mapping;
3264 unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
3266 flags |= AOP_FLAG_NOFS;
3269 err = pagecache_write_begin(NULL, mapping, 0, len-1,
3270 flags, &page, &fsdata);
3274 kaddr = kmap_atomic(page, KM_USER0);
3275 memcpy(kaddr, symname, len-1);
3276 kunmap_atomic(kaddr, KM_USER0);
3278 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
3285 mark_inode_dirty(inode);
3291 int page_symlink(struct inode *inode, const char *symname, int len)
3293 return __page_symlink(inode, symname, len,
3294 !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
3297 const struct inode_operations page_symlink_inode_operations = {
3298 .readlink = generic_readlink,
3299 .follow_link = page_follow_link_light,
3300 .put_link = page_put_link,
3303 EXPORT_SYMBOL(user_path_at);
3304 EXPORT_SYMBOL(follow_down_one);
3305 EXPORT_SYMBOL(follow_down);
3306 EXPORT_SYMBOL(follow_up);
3307 EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
3308 EXPORT_SYMBOL(getname);
3309 EXPORT_SYMBOL(lock_rename);
3310 EXPORT_SYMBOL(lookup_one_len);
3311 EXPORT_SYMBOL(page_follow_link_light);
3312 EXPORT_SYMBOL(page_put_link);
3313 EXPORT_SYMBOL(page_readlink);
3314 EXPORT_SYMBOL(__page_symlink);
3315 EXPORT_SYMBOL(page_symlink);
3316 EXPORT_SYMBOL(page_symlink_inode_operations);
3317 EXPORT_SYMBOL(kern_path);
3318 EXPORT_SYMBOL(vfs_path_lookup);
3319 EXPORT_SYMBOL(inode_permission);
3320 EXPORT_SYMBOL(unlock_rename);
3321 EXPORT_SYMBOL(vfs_create);
3322 EXPORT_SYMBOL(vfs_follow_link);
3323 EXPORT_SYMBOL(vfs_link);
3324 EXPORT_SYMBOL(vfs_mkdir);
3325 EXPORT_SYMBOL(vfs_mknod);
3326 EXPORT_SYMBOL(generic_permission);
3327 EXPORT_SYMBOL(vfs_readlink);
3328 EXPORT_SYMBOL(vfs_rename);
3329 EXPORT_SYMBOL(vfs_rmdir);
3330 EXPORT_SYMBOL(vfs_symlink);
3331 EXPORT_SYMBOL(vfs_unlink);
3332 EXPORT_SYMBOL(dentry_unhash);
3333 EXPORT_SYMBOL(generic_readlink);