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 #ifdef CONFIG_FS_POSIX_ACL
180 struct posix_acl *acl;
182 if (mask & MAY_NOT_BLOCK) {
183 acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
186 /* no ->get_acl() calls in RCU mode... */
187 if (acl == ACL_NOT_CACHED)
189 return posix_acl_permission(inode, acl, mask);
192 acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
195 * A filesystem can force a ACL callback by just never filling the
196 * ACL cache. But normally you'd fill the cache either at inode
197 * instantiation time, or on the first ->get_acl call.
199 * If the filesystem doesn't have a get_acl() function at all, we'll
200 * just create the negative cache entry.
202 if (acl == ACL_NOT_CACHED) {
203 if (inode->i_op->get_acl) {
204 acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS);
208 set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
214 int error = posix_acl_permission(inode, acl, mask);
215 posix_acl_release(acl);
224 * This does basic POSIX ACL permission checking
226 static int acl_permission_check(struct inode *inode, int mask)
228 unsigned int mode = inode->i_mode;
230 mask &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
232 if (current_user_ns() != inode_userns(inode))
235 if (likely(current_fsuid() == inode->i_uid))
238 if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
239 int error = check_acl(inode, mask);
240 if (error != -EAGAIN)
244 if (in_group_p(inode->i_gid))
250 * If the DACs are ok we don't need any capability check.
252 if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
258 * generic_permission - check for access rights on a Posix-like filesystem
259 * @inode: inode to check access rights for
260 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
262 * Used to check for read/write/execute permissions on a file.
263 * We use "fsuid" for this, letting us set arbitrary permissions
264 * for filesystem access without changing the "normal" uids which
265 * are used for other things.
267 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
268 * request cannot be satisfied (eg. requires blocking or too much complexity).
269 * It would then be called again in ref-walk mode.
271 int generic_permission(struct inode *inode, int mask)
276 * Do the basic POSIX ACL permission checks.
278 ret = acl_permission_check(inode, mask);
282 if (S_ISDIR(inode->i_mode)) {
283 /* DACs are overridable for directories */
284 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
286 if (!(mask & MAY_WRITE))
287 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
292 * Read/write DACs are always overridable.
293 * Executable DACs are overridable when there is
294 * at least one exec bit set.
296 if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
297 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
301 * Searching includes executable on directories, else just read.
303 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
304 if (mask == MAY_READ)
305 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
312 * inode_permission - check for access rights to a given inode
313 * @inode: inode to check permission on
314 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
316 * Used to check for read/write/execute permissions on an inode.
317 * We use "fsuid" for this, letting us set arbitrary permissions
318 * for filesystem access without changing the "normal" uids which
319 * are used for other things.
321 int inode_permission(struct inode *inode, int mask)
325 if (mask & MAY_WRITE) {
326 umode_t mode = inode->i_mode;
329 * Nobody gets write access to a read-only fs.
331 if (IS_RDONLY(inode) &&
332 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
336 * Nobody gets write access to an immutable file.
338 if (IS_IMMUTABLE(inode))
342 if (inode->i_op->permission)
343 retval = inode->i_op->permission(inode, mask);
345 retval = generic_permission(inode, mask);
350 retval = devcgroup_inode_permission(inode, mask);
354 return security_inode_permission(inode, mask);
358 * path_get - get a reference to a path
359 * @path: path to get the reference to
361 * Given a path increment the reference count to the dentry and the vfsmount.
363 void path_get(struct path *path)
368 EXPORT_SYMBOL(path_get);
371 * path_put - put a reference to a path
372 * @path: path to put the reference to
374 * Given a path decrement the reference count to the dentry and the vfsmount.
376 void path_put(struct path *path)
381 EXPORT_SYMBOL(path_put);
384 * Path walking has 2 modes, rcu-walk and ref-walk (see
385 * Documentation/filesystems/path-lookup.txt). In situations when we can't
386 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
387 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
388 * mode. Refcounts are grabbed at the last known good point before rcu-walk
389 * got stuck, so ref-walk may continue from there. If this is not successful
390 * (eg. a seqcount has changed), then failure is returned and it's up to caller
391 * to restart the path walk from the beginning in ref-walk mode.
395 * unlazy_walk - try to switch to ref-walk mode.
396 * @nd: nameidata pathwalk data
397 * @dentry: child of nd->path.dentry or NULL
398 * Returns: 0 on success, -ECHILD on failure
400 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
401 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
402 * @nd or NULL. Must be called from rcu-walk context.
404 static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
406 struct fs_struct *fs = current->fs;
407 struct dentry *parent = nd->path.dentry;
410 BUG_ON(!(nd->flags & LOOKUP_RCU));
411 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
413 spin_lock(&fs->lock);
414 if (nd->root.mnt != fs->root.mnt ||
415 nd->root.dentry != fs->root.dentry)
418 spin_lock(&parent->d_lock);
420 if (!__d_rcu_to_refcount(parent, nd->seq))
422 BUG_ON(nd->inode != parent->d_inode);
424 if (dentry->d_parent != parent)
426 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
427 if (!__d_rcu_to_refcount(dentry, nd->seq))
430 * If the sequence check on the child dentry passed, then
431 * the child has not been removed from its parent. This
432 * means the parent dentry must be valid and able to take
433 * a reference at this point.
435 BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent);
436 BUG_ON(!parent->d_count);
438 spin_unlock(&dentry->d_lock);
440 spin_unlock(&parent->d_lock);
443 spin_unlock(&fs->lock);
445 mntget(nd->path.mnt);
448 br_read_unlock(vfsmount_lock);
449 nd->flags &= ~LOOKUP_RCU;
453 spin_unlock(&dentry->d_lock);
455 spin_unlock(&parent->d_lock);
458 spin_unlock(&fs->lock);
463 * release_open_intent - free up open intent resources
464 * @nd: pointer to nameidata
466 void release_open_intent(struct nameidata *nd)
468 struct file *file = nd->intent.open.file;
470 if (file && !IS_ERR(file)) {
471 if (file->f_path.dentry == NULL)
478 static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
480 return dentry->d_op->d_revalidate(dentry, nd);
484 * complete_walk - successful completion of path walk
485 * @nd: pointer nameidata
487 * If we had been in RCU mode, drop out of it and legitimize nd->path.
488 * Revalidate the final result, unless we'd already done that during
489 * the path walk or the filesystem doesn't ask for it. Return 0 on
490 * success, -error on failure. In case of failure caller does not
491 * need to drop nd->path.
493 static int complete_walk(struct nameidata *nd)
495 struct dentry *dentry = nd->path.dentry;
498 if (nd->flags & LOOKUP_RCU) {
499 nd->flags &= ~LOOKUP_RCU;
500 if (!(nd->flags & LOOKUP_ROOT))
502 spin_lock(&dentry->d_lock);
503 if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
504 spin_unlock(&dentry->d_lock);
506 br_read_unlock(vfsmount_lock);
509 BUG_ON(nd->inode != dentry->d_inode);
510 spin_unlock(&dentry->d_lock);
511 mntget(nd->path.mnt);
513 br_read_unlock(vfsmount_lock);
516 if (likely(!(nd->flags & LOOKUP_JUMPED)))
519 if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
522 if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
525 /* Note: we do not d_invalidate() */
526 status = d_revalidate(dentry, nd);
537 static __always_inline void set_root(struct nameidata *nd)
540 get_fs_root(current->fs, &nd->root);
543 static int link_path_walk(const char *, struct nameidata *);
545 static __always_inline void set_root_rcu(struct nameidata *nd)
548 struct fs_struct *fs = current->fs;
552 seq = read_seqcount_begin(&fs->seq);
554 nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
555 } while (read_seqcount_retry(&fs->seq, seq));
559 static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
571 nd->flags |= LOOKUP_JUMPED;
573 nd->inode = nd->path.dentry->d_inode;
575 ret = link_path_walk(link, nd);
579 return PTR_ERR(link);
582 static void path_put_conditional(struct path *path, struct nameidata *nd)
585 if (path->mnt != nd->path.mnt)
589 static inline void path_to_nameidata(const struct path *path,
590 struct nameidata *nd)
592 if (!(nd->flags & LOOKUP_RCU)) {
593 dput(nd->path.dentry);
594 if (nd->path.mnt != path->mnt)
595 mntput(nd->path.mnt);
597 nd->path.mnt = path->mnt;
598 nd->path.dentry = path->dentry;
601 static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
603 struct inode *inode = link->dentry->d_inode;
604 if (!IS_ERR(cookie) && inode->i_op->put_link)
605 inode->i_op->put_link(link->dentry, nd, cookie);
609 static __always_inline int
610 follow_link(struct path *link, struct nameidata *nd, void **p)
613 struct dentry *dentry = link->dentry;
615 BUG_ON(nd->flags & LOOKUP_RCU);
617 if (link->mnt == nd->path.mnt)
620 if (unlikely(current->total_link_count >= 40)) {
621 *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
626 current->total_link_count++;
628 touch_atime(link->mnt, dentry);
629 nd_set_link(nd, NULL);
631 error = security_inode_follow_link(link->dentry, nd);
633 *p = ERR_PTR(error); /* no ->put_link(), please */
638 nd->last_type = LAST_BIND;
639 *p = dentry->d_inode->i_op->follow_link(dentry, nd);
642 char *s = nd_get_link(nd);
645 error = __vfs_follow_link(nd, s);
646 else if (nd->last_type == LAST_BIND) {
647 nd->flags |= LOOKUP_JUMPED;
648 nd->inode = nd->path.dentry->d_inode;
649 if (nd->inode->i_op->follow_link) {
650 /* stepped on a _really_ weird one */
659 static int follow_up_rcu(struct path *path)
661 struct vfsmount *parent;
662 struct dentry *mountpoint;
664 parent = path->mnt->mnt_parent;
665 if (parent == path->mnt)
667 mountpoint = path->mnt->mnt_mountpoint;
668 path->dentry = mountpoint;
673 int follow_up(struct path *path)
675 struct vfsmount *parent;
676 struct dentry *mountpoint;
678 br_read_lock(vfsmount_lock);
679 parent = path->mnt->mnt_parent;
680 if (parent == path->mnt) {
681 br_read_unlock(vfsmount_lock);
685 mountpoint = dget(path->mnt->mnt_mountpoint);
686 br_read_unlock(vfsmount_lock);
688 path->dentry = mountpoint;
695 * Perform an automount
696 * - return -EISDIR to tell follow_managed() to stop and return the path we
699 static int follow_automount(struct path *path, unsigned flags,
702 struct vfsmount *mnt;
705 if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
708 /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT
709 * and this is the terminal part of the path.
711 if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_PARENT))
712 return -EISDIR; /* we actually want to stop here */
715 * We don't want to mount if someone's just doing a stat and they've
716 * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and
717 * appended a '/' to the name.
719 if (!(flags & LOOKUP_FOLLOW)) {
720 /* We do, however, want to mount if someone wants to open or
721 * create a file of any type under the mountpoint, wants to
722 * traverse through the mountpoint or wants to open the mounted
724 * Also, autofs may mark negative dentries as being automount
725 * points. These will need the attentions of the daemon to
726 * instantiate them before they can be used.
728 if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
729 LOOKUP_OPEN | LOOKUP_CREATE)) &&
730 path->dentry->d_inode)
733 current->total_link_count++;
734 if (current->total_link_count >= 40)
737 mnt = path->dentry->d_op->d_automount(path);
740 * The filesystem is allowed to return -EISDIR here to indicate
741 * it doesn't want to automount. For instance, autofs would do
742 * this so that its userspace daemon can mount on this dentry.
744 * However, we can only permit this if it's a terminal point in
745 * the path being looked up; if it wasn't then the remainder of
746 * the path is inaccessible and we should say so.
748 if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT))
753 if (!mnt) /* mount collision */
757 /* lock_mount() may release path->mnt on error */
761 err = finish_automount(mnt, path);
765 /* Someone else made a mount here whilst we were busy */
770 path->dentry = dget(mnt->mnt_root);
779 * Handle a dentry that is managed in some way.
780 * - Flagged for transit management (autofs)
781 * - Flagged as mountpoint
782 * - Flagged as automount point
784 * This may only be called in refwalk mode.
786 * Serialization is taken care of in namespace.c
788 static int follow_managed(struct path *path, unsigned flags)
790 struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
792 bool need_mntput = false;
795 /* Given that we're not holding a lock here, we retain the value in a
796 * local variable for each dentry as we look at it so that we don't see
797 * the components of that value change under us */
798 while (managed = ACCESS_ONCE(path->dentry->d_flags),
799 managed &= DCACHE_MANAGED_DENTRY,
800 unlikely(managed != 0)) {
801 /* Allow the filesystem to manage the transit without i_mutex
803 if (managed & DCACHE_MANAGE_TRANSIT) {
804 BUG_ON(!path->dentry->d_op);
805 BUG_ON(!path->dentry->d_op->d_manage);
806 ret = path->dentry->d_op->d_manage(path->dentry, false);
811 /* Transit to a mounted filesystem. */
812 if (managed & DCACHE_MOUNTED) {
813 struct vfsmount *mounted = lookup_mnt(path);
819 path->dentry = dget(mounted->mnt_root);
824 /* Something is mounted on this dentry in another
825 * namespace and/or whatever was mounted there in this
826 * namespace got unmounted before we managed to get the
830 /* Handle an automount point */
831 if (managed & DCACHE_NEED_AUTOMOUNT) {
832 ret = follow_automount(path, flags, &need_mntput);
838 /* We didn't change the current path point */
842 if (need_mntput && path->mnt == mnt)
849 int follow_down_one(struct path *path)
851 struct vfsmount *mounted;
853 mounted = lookup_mnt(path);
858 path->dentry = dget(mounted->mnt_root);
864 static inline bool managed_dentry_might_block(struct dentry *dentry)
866 return (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
867 dentry->d_op->d_manage(dentry, true) < 0);
871 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
872 * we meet a managed dentry that would need blocking.
874 static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
875 struct inode **inode)
878 struct vfsmount *mounted;
880 * Don't forget we might have a non-mountpoint managed dentry
881 * that wants to block transit.
883 if (unlikely(managed_dentry_might_block(path->dentry)))
886 if (!d_mountpoint(path->dentry))
889 mounted = __lookup_mnt(path->mnt, path->dentry, 1);
893 path->dentry = mounted->mnt_root;
894 nd->seq = read_seqcount_begin(&path->dentry->d_seq);
896 * Update the inode too. We don't need to re-check the
897 * dentry sequence number here after this d_inode read,
898 * because a mount-point is always pinned.
900 *inode = path->dentry->d_inode;
905 static void follow_mount_rcu(struct nameidata *nd)
907 while (d_mountpoint(nd->path.dentry)) {
908 struct vfsmount *mounted;
909 mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
912 nd->path.mnt = mounted;
913 nd->path.dentry = mounted->mnt_root;
914 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
918 static int follow_dotdot_rcu(struct nameidata *nd)
923 if (nd->path.dentry == nd->root.dentry &&
924 nd->path.mnt == nd->root.mnt) {
927 if (nd->path.dentry != nd->path.mnt->mnt_root) {
928 struct dentry *old = nd->path.dentry;
929 struct dentry *parent = old->d_parent;
932 seq = read_seqcount_begin(&parent->d_seq);
933 if (read_seqcount_retry(&old->d_seq, nd->seq))
935 nd->path.dentry = parent;
939 if (!follow_up_rcu(&nd->path))
941 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
943 follow_mount_rcu(nd);
944 nd->inode = nd->path.dentry->d_inode;
948 nd->flags &= ~LOOKUP_RCU;
949 if (!(nd->flags & LOOKUP_ROOT))
952 br_read_unlock(vfsmount_lock);
957 * Follow down to the covering mount currently visible to userspace. At each
958 * point, the filesystem owning that dentry may be queried as to whether the
959 * caller is permitted to proceed or not.
961 int follow_down(struct path *path)
966 while (managed = ACCESS_ONCE(path->dentry->d_flags),
967 unlikely(managed & DCACHE_MANAGED_DENTRY)) {
968 /* Allow the filesystem to manage the transit without i_mutex
971 * We indicate to the filesystem if someone is trying to mount
972 * something here. This gives autofs the chance to deny anyone
973 * other than its daemon the right to mount on its
976 * The filesystem may sleep at this point.
978 if (managed & DCACHE_MANAGE_TRANSIT) {
979 BUG_ON(!path->dentry->d_op);
980 BUG_ON(!path->dentry->d_op->d_manage);
981 ret = path->dentry->d_op->d_manage(
982 path->dentry, false);
984 return ret == -EISDIR ? 0 : ret;
987 /* Transit to a mounted filesystem. */
988 if (managed & DCACHE_MOUNTED) {
989 struct vfsmount *mounted = lookup_mnt(path);
995 path->dentry = dget(mounted->mnt_root);
999 /* Don't handle automount points here */
1006 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1008 static void follow_mount(struct path *path)
1010 while (d_mountpoint(path->dentry)) {
1011 struct vfsmount *mounted = lookup_mnt(path);
1016 path->mnt = mounted;
1017 path->dentry = dget(mounted->mnt_root);
1021 static void follow_dotdot(struct nameidata *nd)
1026 struct dentry *old = nd->path.dentry;
1028 if (nd->path.dentry == nd->root.dentry &&
1029 nd->path.mnt == nd->root.mnt) {
1032 if (nd->path.dentry != nd->path.mnt->mnt_root) {
1033 /* rare case of legitimate dget_parent()... */
1034 nd->path.dentry = dget_parent(nd->path.dentry);
1038 if (!follow_up(&nd->path))
1041 follow_mount(&nd->path);
1042 nd->inode = nd->path.dentry->d_inode;
1046 * Allocate a dentry with name and parent, and perform a parent
1047 * directory ->lookup on it. Returns the new dentry, or ERR_PTR
1048 * on error. parent->d_inode->i_mutex must be held. d_lookup must
1049 * have verified that no child exists while under i_mutex.
1051 static struct dentry *d_alloc_and_lookup(struct dentry *parent,
1052 struct qstr *name, struct nameidata *nd)
1054 struct inode *inode = parent->d_inode;
1055 struct dentry *dentry;
1058 /* Don't create child dentry for a dead directory. */
1059 if (unlikely(IS_DEADDIR(inode)))
1060 return ERR_PTR(-ENOENT);
1062 dentry = d_alloc(parent, name);
1063 if (unlikely(!dentry))
1064 return ERR_PTR(-ENOMEM);
1066 old = inode->i_op->lookup(inode, dentry, nd);
1067 if (unlikely(old)) {
1075 * We already have a dentry, but require a lookup to be performed on the parent
1076 * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error.
1077 * parent->d_inode->i_mutex must be held. d_lookup must have verified that no
1078 * child exists while under i_mutex.
1080 static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry,
1081 struct nameidata *nd)
1083 struct inode *inode = parent->d_inode;
1086 /* Don't create child dentry for a dead directory. */
1087 if (unlikely(IS_DEADDIR(inode)))
1088 return ERR_PTR(-ENOENT);
1090 old = inode->i_op->lookup(inode, dentry, nd);
1091 if (unlikely(old)) {
1099 * It's more convoluted than I'd like it to be, but... it's still fairly
1100 * small and for now I'd prefer to have fast path as straight as possible.
1101 * It _is_ time-critical.
1103 static int do_lookup(struct nameidata *nd, struct qstr *name,
1104 struct path *path, struct inode **inode)
1106 struct vfsmount *mnt = nd->path.mnt;
1107 struct dentry *dentry, *parent = nd->path.dentry;
1113 * Rename seqlock is not required here because in the off chance
1114 * of a false negative due to a concurrent rename, we're going to
1115 * do the non-racy lookup, below.
1117 if (nd->flags & LOOKUP_RCU) {
1120 dentry = __d_lookup_rcu(parent, name, &seq, inode);
1124 /* Memory barrier in read_seqcount_begin of child is enough */
1125 if (__read_seqcount_retry(&parent->d_seq, nd->seq))
1129 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
1130 status = d_revalidate(dentry, nd);
1131 if (unlikely(status <= 0)) {
1132 if (status != -ECHILD)
1137 if (unlikely(d_need_lookup(dentry)))
1140 path->dentry = dentry;
1141 if (unlikely(!__follow_mount_rcu(nd, path, inode)))
1143 if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
1147 if (unlazy_walk(nd, dentry))
1150 dentry = __d_lookup(parent, name);
1153 if (dentry && unlikely(d_need_lookup(dentry))) {
1158 if (unlikely(!dentry)) {
1159 struct inode *dir = parent->d_inode;
1160 BUG_ON(nd->inode != dir);
1162 mutex_lock(&dir->i_mutex);
1163 dentry = d_lookup(parent, name);
1164 if (likely(!dentry)) {
1165 dentry = d_alloc_and_lookup(parent, name, nd);
1166 if (IS_ERR(dentry)) {
1167 mutex_unlock(&dir->i_mutex);
1168 return PTR_ERR(dentry);
1173 } else if (unlikely(d_need_lookup(dentry))) {
1174 dentry = d_inode_lookup(parent, dentry, nd);
1175 if (IS_ERR(dentry)) {
1176 mutex_unlock(&dir->i_mutex);
1177 return PTR_ERR(dentry);
1183 mutex_unlock(&dir->i_mutex);
1185 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
1186 status = d_revalidate(dentry, nd);
1187 if (unlikely(status <= 0)) {
1192 if (!d_invalidate(dentry)) {
1201 path->dentry = dentry;
1202 err = follow_managed(path, nd->flags);
1203 if (unlikely(err < 0)) {
1204 path_put_conditional(path, nd);
1207 *inode = path->dentry->d_inode;
1211 static inline int may_lookup(struct nameidata *nd)
1213 if (nd->flags & LOOKUP_RCU) {
1214 int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
1217 if (unlazy_walk(nd, NULL))
1220 return inode_permission(nd->inode, MAY_EXEC);
1223 static inline int handle_dots(struct nameidata *nd, int type)
1225 if (type == LAST_DOTDOT) {
1226 if (nd->flags & LOOKUP_RCU) {
1227 if (follow_dotdot_rcu(nd))
1235 static void terminate_walk(struct nameidata *nd)
1237 if (!(nd->flags & LOOKUP_RCU)) {
1238 path_put(&nd->path);
1240 nd->flags &= ~LOOKUP_RCU;
1241 if (!(nd->flags & LOOKUP_ROOT))
1242 nd->root.mnt = NULL;
1244 br_read_unlock(vfsmount_lock);
1248 static inline int walk_component(struct nameidata *nd, struct path *path,
1249 struct qstr *name, int type, int follow)
1251 struct inode *inode;
1254 * "." and ".." are special - ".." especially so because it has
1255 * to be able to know about the current root directory and
1256 * parent relationships.
1258 if (unlikely(type != LAST_NORM))
1259 return handle_dots(nd, type);
1260 err = do_lookup(nd, name, path, &inode);
1261 if (unlikely(err)) {
1266 path_to_nameidata(path, nd);
1270 if (unlikely(inode->i_op->follow_link) && follow) {
1271 if (nd->flags & LOOKUP_RCU) {
1272 if (unlikely(unlazy_walk(nd, path->dentry))) {
1277 BUG_ON(inode != path->dentry->d_inode);
1280 path_to_nameidata(path, nd);
1286 * This limits recursive symlink follows to 8, while
1287 * limiting consecutive symlinks to 40.
1289 * Without that kind of total limit, nasty chains of consecutive
1290 * symlinks can cause almost arbitrarily long lookups.
1292 static inline int nested_symlink(struct path *path, struct nameidata *nd)
1296 if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
1297 path_put_conditional(path, nd);
1298 path_put(&nd->path);
1301 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
1304 current->link_count++;
1307 struct path link = *path;
1310 res = follow_link(&link, nd, &cookie);
1312 res = walk_component(nd, path, &nd->last,
1313 nd->last_type, LOOKUP_FOLLOW);
1314 put_link(nd, &link, cookie);
1317 current->link_count--;
1324 * This is the basic name resolution function, turning a pathname into
1325 * the final dentry. We expect 'base' to be positive and a directory.
1327 * Returns 0 and nd will have valid dentry and mnt on success.
1328 * Returns error and drops reference to input namei data on failure.
1330 static int link_path_walk(const char *name, struct nameidata *nd)
1340 /* At this point we know we have a real path component. */
1347 err = may_lookup(nd);
1352 c = *(const unsigned char *)name;
1354 hash = init_name_hash();
1357 hash = partial_name_hash(c, hash);
1358 c = *(const unsigned char *)name;
1359 } while (c && (c != '/'));
1360 this.len = name - (const char *) this.name;
1361 this.hash = end_name_hash(hash);
1364 if (this.name[0] == '.') switch (this.len) {
1366 if (this.name[1] == '.') {
1368 nd->flags |= LOOKUP_JUMPED;
1374 if (likely(type == LAST_NORM)) {
1375 struct dentry *parent = nd->path.dentry;
1376 nd->flags &= ~LOOKUP_JUMPED;
1377 if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
1378 err = parent->d_op->d_hash(parent, nd->inode,
1385 /* remove trailing slashes? */
1387 goto last_component;
1388 while (*++name == '/');
1390 goto last_component;
1392 err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW);
1397 err = nested_symlink(&next, nd);
1402 if (!nd->inode->i_op->lookup)
1405 /* here ends the main loop */
1409 nd->last_type = type;
1416 static int path_init(int dfd, const char *name, unsigned int flags,
1417 struct nameidata *nd, struct file **fp)
1423 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1424 nd->flags = flags | LOOKUP_JUMPED;
1426 if (flags & LOOKUP_ROOT) {
1427 struct inode *inode = nd->root.dentry->d_inode;
1429 if (!inode->i_op->lookup)
1431 retval = inode_permission(inode, MAY_EXEC);
1435 nd->path = nd->root;
1437 if (flags & LOOKUP_RCU) {
1438 br_read_lock(vfsmount_lock);
1440 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1442 path_get(&nd->path);
1447 nd->root.mnt = NULL;
1450 if (flags & LOOKUP_RCU) {
1451 br_read_lock(vfsmount_lock);
1456 path_get(&nd->root);
1458 nd->path = nd->root;
1459 } else if (dfd == AT_FDCWD) {
1460 if (flags & LOOKUP_RCU) {
1461 struct fs_struct *fs = current->fs;
1464 br_read_lock(vfsmount_lock);
1468 seq = read_seqcount_begin(&fs->seq);
1470 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1471 } while (read_seqcount_retry(&fs->seq, seq));
1473 get_fs_pwd(current->fs, &nd->path);
1476 struct dentry *dentry;
1478 file = fget_raw_light(dfd, &fput_needed);
1483 dentry = file->f_path.dentry;
1487 if (!S_ISDIR(dentry->d_inode->i_mode))
1490 retval = inode_permission(dentry->d_inode, MAY_EXEC);
1495 nd->path = file->f_path;
1496 if (flags & LOOKUP_RCU) {
1499 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1500 br_read_lock(vfsmount_lock);
1503 path_get(&file->f_path);
1504 fput_light(file, fput_needed);
1508 nd->inode = nd->path.dentry->d_inode;
1512 fput_light(file, fput_needed);
1517 static inline int lookup_last(struct nameidata *nd, struct path *path)
1519 if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
1520 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
1522 nd->flags &= ~LOOKUP_PARENT;
1523 return walk_component(nd, path, &nd->last, nd->last_type,
1524 nd->flags & LOOKUP_FOLLOW);
1527 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1528 static int path_lookupat(int dfd, const char *name,
1529 unsigned int flags, struct nameidata *nd)
1531 struct file *base = NULL;
1536 * Path walking is largely split up into 2 different synchronisation
1537 * schemes, rcu-walk and ref-walk (explained in
1538 * Documentation/filesystems/path-lookup.txt). These share much of the
1539 * path walk code, but some things particularly setup, cleanup, and
1540 * following mounts are sufficiently divergent that functions are
1541 * duplicated. Typically there is a function foo(), and its RCU
1542 * analogue, foo_rcu().
1544 * -ECHILD is the error number of choice (just to avoid clashes) that
1545 * is returned if some aspect of an rcu-walk fails. Such an error must
1546 * be handled by restarting a traditional ref-walk (which will always
1547 * be able to complete).
1549 err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);
1554 current->total_link_count = 0;
1555 err = link_path_walk(name, nd);
1557 if (!err && !(flags & LOOKUP_PARENT)) {
1558 err = lookup_last(nd, &path);
1561 struct path link = path;
1562 nd->flags |= LOOKUP_PARENT;
1563 err = follow_link(&link, nd, &cookie);
1565 err = lookup_last(nd, &path);
1566 put_link(nd, &link, cookie);
1571 err = complete_walk(nd);
1573 if (!err && nd->flags & LOOKUP_DIRECTORY) {
1574 if (!nd->inode->i_op->lookup) {
1575 path_put(&nd->path);
1583 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
1584 path_put(&nd->root);
1585 nd->root.mnt = NULL;
1590 static int do_path_lookup(int dfd, const char *name,
1591 unsigned int flags, struct nameidata *nd)
1593 int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd);
1594 if (unlikely(retval == -ECHILD))
1595 retval = path_lookupat(dfd, name, flags, nd);
1596 if (unlikely(retval == -ESTALE))
1597 retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd);
1599 if (likely(!retval)) {
1600 if (unlikely(!audit_dummy_context())) {
1601 if (nd->path.dentry && nd->inode)
1602 audit_inode(name, nd->path.dentry);
1608 int kern_path_parent(const char *name, struct nameidata *nd)
1610 return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd);
1613 int kern_path(const char *name, unsigned int flags, struct path *path)
1615 struct nameidata nd;
1616 int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
1623 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1624 * @dentry: pointer to dentry of the base directory
1625 * @mnt: pointer to vfs mount of the base directory
1626 * @name: pointer to file name
1627 * @flags: lookup flags
1628 * @path: pointer to struct path to fill
1630 int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
1631 const char *name, unsigned int flags,
1634 struct nameidata nd;
1636 nd.root.dentry = dentry;
1638 BUG_ON(flags & LOOKUP_PARENT);
1639 /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
1640 err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd);
1646 static struct dentry *__lookup_hash(struct qstr *name,
1647 struct dentry *base, struct nameidata *nd)
1649 struct inode *inode = base->d_inode;
1650 struct dentry *dentry;
1653 err = inode_permission(inode, MAY_EXEC);
1655 return ERR_PTR(err);
1658 * Don't bother with __d_lookup: callers are for creat as
1659 * well as unlink, so a lot of the time it would cost
1662 dentry = d_lookup(base, name);
1664 if (dentry && d_need_lookup(dentry)) {
1666 * __lookup_hash is called with the parent dir's i_mutex already
1667 * held, so we are good to go here.
1669 dentry = d_inode_lookup(base, dentry, nd);
1674 if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) {
1675 int status = d_revalidate(dentry, nd);
1676 if (unlikely(status <= 0)) {
1678 * The dentry failed validation.
1679 * If d_revalidate returned 0 attempt to invalidate
1680 * the dentry otherwise d_revalidate is asking us
1681 * to return a fail status.
1685 return ERR_PTR(status);
1686 } else if (!d_invalidate(dentry)) {
1694 dentry = d_alloc_and_lookup(base, name, nd);
1700 * Restricted form of lookup. Doesn't follow links, single-component only,
1701 * needs parent already locked. Doesn't follow mounts.
1704 static struct dentry *lookup_hash(struct nameidata *nd)
1706 return __lookup_hash(&nd->last, nd->path.dentry, nd);
1710 * lookup_one_len - filesystem helper to lookup single pathname component
1711 * @name: pathname component to lookup
1712 * @base: base directory to lookup from
1713 * @len: maximum length @len should be interpreted to
1715 * Note that this routine is purely a helper for filesystem usage and should
1716 * not be called by generic code. Also note that by using this function the
1717 * nameidata argument is passed to the filesystem methods and a filesystem
1718 * using this helper needs to be prepared for that.
1720 struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
1726 WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
1731 return ERR_PTR(-EACCES);
1733 hash = init_name_hash();
1735 c = *(const unsigned char *)name++;
1736 if (c == '/' || c == '\0')
1737 return ERR_PTR(-EACCES);
1738 hash = partial_name_hash(c, hash);
1740 this.hash = end_name_hash(hash);
1742 * See if the low-level filesystem might want
1743 * to use its own hash..
1745 if (base->d_flags & DCACHE_OP_HASH) {
1746 int err = base->d_op->d_hash(base, base->d_inode, &this);
1748 return ERR_PTR(err);
1751 return __lookup_hash(&this, base, NULL);
1754 int user_path_at(int dfd, const char __user *name, unsigned flags,
1757 struct nameidata nd;
1758 char *tmp = getname_flags(name, flags);
1759 int err = PTR_ERR(tmp);
1762 BUG_ON(flags & LOOKUP_PARENT);
1764 err = do_path_lookup(dfd, tmp, flags, &nd);
1772 static int user_path_parent(int dfd, const char __user *path,
1773 struct nameidata *nd, char **name)
1775 char *s = getname(path);
1781 error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
1791 * It's inline, so penalty for filesystems that don't use sticky bit is
1794 static inline int check_sticky(struct inode *dir, struct inode *inode)
1796 uid_t fsuid = current_fsuid();
1798 if (!(dir->i_mode & S_ISVTX))
1800 if (current_user_ns() != inode_userns(inode))
1802 if (inode->i_uid == fsuid)
1804 if (dir->i_uid == fsuid)
1808 return !ns_capable(inode_userns(inode), CAP_FOWNER);
1812 * Check whether we can remove a link victim from directory dir, check
1813 * whether the type of victim is right.
1814 * 1. We can't do it if dir is read-only (done in permission())
1815 * 2. We should have write and exec permissions on dir
1816 * 3. We can't remove anything from append-only dir
1817 * 4. We can't do anything with immutable dir (done in permission())
1818 * 5. If the sticky bit on dir is set we should either
1819 * a. be owner of dir, or
1820 * b. be owner of victim, or
1821 * c. have CAP_FOWNER capability
1822 * 6. If the victim is append-only or immutable we can't do antyhing with
1823 * links pointing to it.
1824 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1825 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1826 * 9. We can't remove a root or mountpoint.
1827 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1828 * nfs_async_unlink().
1830 static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1834 if (!victim->d_inode)
1837 BUG_ON(victim->d_parent->d_inode != dir);
1838 audit_inode_child(victim, dir);
1840 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
1845 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1846 IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
1849 if (!S_ISDIR(victim->d_inode->i_mode))
1851 if (IS_ROOT(victim))
1853 } else if (S_ISDIR(victim->d_inode->i_mode))
1855 if (IS_DEADDIR(dir))
1857 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1862 /* Check whether we can create an object with dentry child in directory
1864 * 1. We can't do it if child already exists (open has special treatment for
1865 * this case, but since we are inlined it's OK)
1866 * 2. We can't do it if dir is read-only (done in permission())
1867 * 3. We should have write and exec permissions on dir
1868 * 4. We can't do it if dir is immutable (done in permission())
1870 static inline int may_create(struct inode *dir, struct dentry *child)
1874 if (IS_DEADDIR(dir))
1876 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
1880 * p1 and p2 should be directories on the same fs.
1882 struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1887 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1891 mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1893 p = d_ancestor(p2, p1);
1895 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
1896 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
1900 p = d_ancestor(p1, p2);
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 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1908 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1912 void unlock_rename(struct dentry *p1, struct dentry *p2)
1914 mutex_unlock(&p1->d_inode->i_mutex);
1916 mutex_unlock(&p2->d_inode->i_mutex);
1917 mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1921 int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1922 struct nameidata *nd)
1924 int error = may_create(dir, dentry);
1929 if (!dir->i_op->create)
1930 return -EACCES; /* shouldn't it be ENOSYS? */
1933 error = security_inode_create(dir, dentry, mode);
1936 error = dir->i_op->create(dir, dentry, mode, nd);
1938 fsnotify_create(dir, dentry);
1942 static int may_open(struct path *path, int acc_mode, int flag)
1944 struct dentry *dentry = path->dentry;
1945 struct inode *inode = dentry->d_inode;
1955 switch (inode->i_mode & S_IFMT) {
1959 if (acc_mode & MAY_WRITE)
1964 if (path->mnt->mnt_flags & MNT_NODEV)
1973 error = inode_permission(inode, acc_mode);
1978 * An append-only file must be opened in append mode for writing.
1980 if (IS_APPEND(inode)) {
1981 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
1987 /* O_NOATIME can only be set by the owner or superuser */
1988 if (flag & O_NOATIME && !inode_owner_or_capable(inode))
1992 * Ensure there are no outstanding leases on the file.
1994 return break_lease(inode, flag);
1997 static int handle_truncate(struct file *filp)
1999 struct path *path = &filp->f_path;
2000 struct inode *inode = path->dentry->d_inode;
2001 int error = get_write_access(inode);
2005 * Refuse to truncate files with mandatory locks held on them.
2007 error = locks_verify_locked(inode);
2009 error = security_path_truncate(path);
2011 error = do_truncate(path->dentry, 0,
2012 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
2015 put_write_access(inode);
2019 static inline int open_to_namei_flags(int flag)
2021 if ((flag & O_ACCMODE) == 3)
2027 * Handle the last step of open()
2029 static struct file *do_last(struct nameidata *nd, struct path *path,
2030 const struct open_flags *op, const char *pathname)
2032 struct dentry *dir = nd->path.dentry;
2033 struct dentry *dentry;
2034 int open_flag = op->open_flag;
2035 int will_truncate = open_flag & O_TRUNC;
2037 int acc_mode = op->acc_mode;
2041 nd->flags &= ~LOOKUP_PARENT;
2042 nd->flags |= op->intent;
2044 switch (nd->last_type) {
2047 error = handle_dots(nd, nd->last_type);
2049 return ERR_PTR(error);
2052 error = complete_walk(nd);
2054 return ERR_PTR(error);
2055 audit_inode(pathname, nd->path.dentry);
2056 if (open_flag & O_CREAT) {
2062 error = complete_walk(nd);
2064 return ERR_PTR(error);
2065 audit_inode(pathname, dir);
2069 if (!(open_flag & O_CREAT)) {
2071 if (nd->last.name[nd->last.len])
2072 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
2073 if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
2075 /* we _can_ be in RCU mode here */
2076 error = walk_component(nd, path, &nd->last, LAST_NORM,
2079 return ERR_PTR(error);
2080 if (error) /* symlink */
2083 error = complete_walk(nd);
2085 return ERR_PTR(-ECHILD);
2088 if (nd->flags & LOOKUP_DIRECTORY) {
2089 if (!nd->inode->i_op->lookup)
2092 audit_inode(pathname, nd->path.dentry);
2096 /* create side of things */
2097 error = complete_walk(nd);
2099 return ERR_PTR(error);
2101 audit_inode(pathname, dir);
2103 /* trailing slashes? */
2104 if (nd->last.name[nd->last.len])
2107 mutex_lock(&dir->d_inode->i_mutex);
2109 dentry = lookup_hash(nd);
2110 error = PTR_ERR(dentry);
2111 if (IS_ERR(dentry)) {
2112 mutex_unlock(&dir->d_inode->i_mutex);
2116 path->dentry = dentry;
2117 path->mnt = nd->path.mnt;
2119 /* Negative dentry, just create the file */
2120 if (!dentry->d_inode) {
2121 int mode = op->mode;
2122 if (!IS_POSIXACL(dir->d_inode))
2123 mode &= ~current_umask();
2125 * This write is needed to ensure that a
2126 * rw->ro transition does not occur between
2127 * the time when the file is created and when
2128 * a permanent write count is taken through
2129 * the 'struct file' in nameidata_to_filp().
2131 error = mnt_want_write(nd->path.mnt);
2133 goto exit_mutex_unlock;
2135 /* Don't check for write permission, don't truncate */
2136 open_flag &= ~O_TRUNC;
2138 acc_mode = MAY_OPEN;
2139 error = security_path_mknod(&nd->path, dentry, mode, 0);
2141 goto exit_mutex_unlock;
2142 error = vfs_create(dir->d_inode, dentry, mode, nd);
2144 goto exit_mutex_unlock;
2145 mutex_unlock(&dir->d_inode->i_mutex);
2146 dput(nd->path.dentry);
2147 nd->path.dentry = dentry;
2152 * It already exists.
2154 mutex_unlock(&dir->d_inode->i_mutex);
2155 audit_inode(pathname, path->dentry);
2158 if (open_flag & O_EXCL)
2161 error = follow_managed(path, nd->flags);
2166 if (!path->dentry->d_inode)
2169 if (path->dentry->d_inode->i_op->follow_link)
2172 path_to_nameidata(path, nd);
2173 nd->inode = path->dentry->d_inode;
2175 if (S_ISDIR(nd->inode->i_mode))
2178 if (!S_ISREG(nd->inode->i_mode))
2181 if (will_truncate) {
2182 error = mnt_want_write(nd->path.mnt);
2188 error = may_open(&nd->path, acc_mode, open_flag);
2191 filp = nameidata_to_filp(nd);
2192 if (!IS_ERR(filp)) {
2193 error = ima_file_check(filp, op->acc_mode);
2196 filp = ERR_PTR(error);
2199 if (!IS_ERR(filp)) {
2200 if (will_truncate) {
2201 error = handle_truncate(filp);
2204 filp = ERR_PTR(error);
2210 mnt_drop_write(nd->path.mnt);
2211 path_put(&nd->path);
2215 mutex_unlock(&dir->d_inode->i_mutex);
2217 path_put_conditional(path, nd);
2219 filp = ERR_PTR(error);
2223 static struct file *path_openat(int dfd, const char *pathname,
2224 struct nameidata *nd, const struct open_flags *op, int flags)
2226 struct file *base = NULL;
2231 filp = get_empty_filp();
2233 return ERR_PTR(-ENFILE);
2235 filp->f_flags = op->open_flag;
2236 nd->intent.open.file = filp;
2237 nd->intent.open.flags = open_to_namei_flags(op->open_flag);
2238 nd->intent.open.create_mode = op->mode;
2240 error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
2241 if (unlikely(error))
2244 current->total_link_count = 0;
2245 error = link_path_walk(pathname, nd);
2246 if (unlikely(error))
2249 filp = do_last(nd, &path, op, pathname);
2250 while (unlikely(!filp)) { /* trailing symlink */
2251 struct path link = path;
2253 if (!(nd->flags & LOOKUP_FOLLOW)) {
2254 path_put_conditional(&path, nd);
2255 path_put(&nd->path);
2256 filp = ERR_PTR(-ELOOP);
2259 nd->flags |= LOOKUP_PARENT;
2260 nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
2261 error = follow_link(&link, nd, &cookie);
2262 if (unlikely(error))
2263 filp = ERR_PTR(error);
2265 filp = do_last(nd, &path, op, pathname);
2266 put_link(nd, &link, cookie);
2269 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))
2270 path_put(&nd->root);
2273 release_open_intent(nd);
2277 filp = ERR_PTR(error);
2281 struct file *do_filp_open(int dfd, const char *pathname,
2282 const struct open_flags *op, int flags)
2284 struct nameidata nd;
2287 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
2288 if (unlikely(filp == ERR_PTR(-ECHILD)))
2289 filp = path_openat(dfd, pathname, &nd, op, flags);
2290 if (unlikely(filp == ERR_PTR(-ESTALE)))
2291 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL);
2295 struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
2296 const char *name, const struct open_flags *op, int flags)
2298 struct nameidata nd;
2302 nd.root.dentry = dentry;
2304 flags |= LOOKUP_ROOT;
2306 if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
2307 return ERR_PTR(-ELOOP);
2309 file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU);
2310 if (unlikely(file == ERR_PTR(-ECHILD)))
2311 file = path_openat(-1, name, &nd, op, flags);
2312 if (unlikely(file == ERR_PTR(-ESTALE)))
2313 file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL);
2317 struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
2319 struct dentry *dentry = ERR_PTR(-EEXIST);
2320 struct nameidata nd;
2321 int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
2323 return ERR_PTR(error);
2326 * Yucky last component or no last component at all?
2327 * (foo/., foo/.., /////)
2329 if (nd.last_type != LAST_NORM)
2331 nd.flags &= ~LOOKUP_PARENT;
2332 nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL;
2333 nd.intent.open.flags = O_EXCL;
2336 * Do the final lookup.
2338 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2339 dentry = lookup_hash(&nd);
2343 if (dentry->d_inode)
2346 * Special case - lookup gave negative, but... we had foo/bar/
2347 * From the vfs_mknod() POV we just have a negative dentry -
2348 * all is fine. Let's be bastards - you had / on the end, you've
2349 * been asking for (non-existent) directory. -ENOENT for you.
2351 if (unlikely(!is_dir && nd.last.name[nd.last.len])) {
2353 dentry = ERR_PTR(-ENOENT);
2360 dentry = ERR_PTR(-EEXIST);
2362 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2367 EXPORT_SYMBOL(kern_path_create);
2369 struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
2371 char *tmp = getname(pathname);
2374 return ERR_CAST(tmp);
2375 res = kern_path_create(dfd, tmp, path, is_dir);
2379 EXPORT_SYMBOL(user_path_create);
2381 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
2383 int error = may_create(dir, dentry);
2388 if ((S_ISCHR(mode) || S_ISBLK(mode)) &&
2389 !ns_capable(inode_userns(dir), CAP_MKNOD))
2392 if (!dir->i_op->mknod)
2395 error = devcgroup_inode_mknod(mode, dev);
2399 error = security_inode_mknod(dir, dentry, mode, dev);
2403 error = dir->i_op->mknod(dir, dentry, mode, dev);
2405 fsnotify_create(dir, dentry);
2409 static int may_mknod(mode_t mode)
2411 switch (mode & S_IFMT) {
2417 case 0: /* zero mode translates to S_IFREG */
2426 SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
2429 struct dentry *dentry;
2436 dentry = user_path_create(dfd, filename, &path, 0);
2438 return PTR_ERR(dentry);
2440 if (!IS_POSIXACL(path.dentry->d_inode))
2441 mode &= ~current_umask();
2442 error = may_mknod(mode);
2445 error = mnt_want_write(path.mnt);
2448 error = security_path_mknod(&path, dentry, mode, dev);
2450 goto out_drop_write;
2451 switch (mode & S_IFMT) {
2452 case 0: case S_IFREG:
2453 error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
2455 case S_IFCHR: case S_IFBLK:
2456 error = vfs_mknod(path.dentry->d_inode,dentry,mode,
2457 new_decode_dev(dev));
2459 case S_IFIFO: case S_IFSOCK:
2460 error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
2464 mnt_drop_write(path.mnt);
2467 mutex_unlock(&path.dentry->d_inode->i_mutex);
2473 SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev)
2475 return sys_mknodat(AT_FDCWD, filename, mode, dev);
2478 int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
2480 int error = may_create(dir, dentry);
2485 if (!dir->i_op->mkdir)
2488 mode &= (S_IRWXUGO|S_ISVTX);
2489 error = security_inode_mkdir(dir, dentry, mode);
2493 error = dir->i_op->mkdir(dir, dentry, mode);
2495 fsnotify_mkdir(dir, dentry);
2499 SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode)
2501 struct dentry *dentry;
2505 dentry = user_path_create(dfd, pathname, &path, 1);
2507 return PTR_ERR(dentry);
2509 if (!IS_POSIXACL(path.dentry->d_inode))
2510 mode &= ~current_umask();
2511 error = mnt_want_write(path.mnt);
2514 error = security_path_mkdir(&path, dentry, mode);
2516 goto out_drop_write;
2517 error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
2519 mnt_drop_write(path.mnt);
2522 mutex_unlock(&path.dentry->d_inode->i_mutex);
2527 SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode)
2529 return sys_mkdirat(AT_FDCWD, pathname, mode);
2533 * The dentry_unhash() helper will try to drop the dentry early: we
2534 * should have a usage count of 2 if we're the only user of this
2535 * dentry, and if that is true (possibly after pruning the dcache),
2536 * then we drop the dentry now.
2538 * A low-level filesystem can, if it choses, legally
2541 * if (!d_unhashed(dentry))
2544 * if it cannot handle the case of removing a directory
2545 * that is still in use by something else..
2547 void dentry_unhash(struct dentry *dentry)
2549 shrink_dcache_parent(dentry);
2550 spin_lock(&dentry->d_lock);
2551 if (dentry->d_count == 1)
2553 spin_unlock(&dentry->d_lock);
2556 int vfs_rmdir(struct inode *dir, struct dentry *dentry)
2558 int error = may_delete(dir, dentry, 1);
2563 if (!dir->i_op->rmdir)
2566 mutex_lock(&dentry->d_inode->i_mutex);
2569 if (d_mountpoint(dentry))
2572 error = security_inode_rmdir(dir, dentry);
2576 shrink_dcache_parent(dentry);
2577 error = dir->i_op->rmdir(dir, dentry);
2581 dentry->d_inode->i_flags |= S_DEAD;
2585 mutex_unlock(&dentry->d_inode->i_mutex);
2591 static long do_rmdir(int dfd, const char __user *pathname)
2595 struct dentry *dentry;
2596 struct nameidata nd;
2598 error = user_path_parent(dfd, pathname, &nd, &name);
2602 switch(nd.last_type) {
2614 nd.flags &= ~LOOKUP_PARENT;
2616 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2617 dentry = lookup_hash(&nd);
2618 error = PTR_ERR(dentry);
2621 if (!dentry->d_inode) {
2625 error = mnt_want_write(nd.path.mnt);
2628 error = security_path_rmdir(&nd.path, dentry);
2631 error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
2633 mnt_drop_write(nd.path.mnt);
2637 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2644 SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
2646 return do_rmdir(AT_FDCWD, pathname);
2649 int vfs_unlink(struct inode *dir, struct dentry *dentry)
2651 int error = may_delete(dir, dentry, 0);
2656 if (!dir->i_op->unlink)
2659 mutex_lock(&dentry->d_inode->i_mutex);
2660 if (d_mountpoint(dentry))
2663 error = security_inode_unlink(dir, dentry);
2665 error = dir->i_op->unlink(dir, dentry);
2670 mutex_unlock(&dentry->d_inode->i_mutex);
2672 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2673 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
2674 fsnotify_link_count(dentry->d_inode);
2682 * Make sure that the actual truncation of the file will occur outside its
2683 * directory's i_mutex. Truncate can take a long time if there is a lot of
2684 * writeout happening, and we don't want to prevent access to the directory
2685 * while waiting on the I/O.
2687 static long do_unlinkat(int dfd, const char __user *pathname)
2691 struct dentry *dentry;
2692 struct nameidata nd;
2693 struct inode *inode = NULL;
2695 error = user_path_parent(dfd, pathname, &nd, &name);
2700 if (nd.last_type != LAST_NORM)
2703 nd.flags &= ~LOOKUP_PARENT;
2705 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2706 dentry = lookup_hash(&nd);
2707 error = PTR_ERR(dentry);
2708 if (!IS_ERR(dentry)) {
2709 /* Why not before? Because we want correct error value */
2710 if (nd.last.name[nd.last.len])
2712 inode = dentry->d_inode;
2716 error = mnt_want_write(nd.path.mnt);
2719 error = security_path_unlink(&nd.path, dentry);
2722 error = vfs_unlink(nd.path.dentry->d_inode, dentry);
2724 mnt_drop_write(nd.path.mnt);
2728 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2730 iput(inode); /* truncate the inode here */
2737 error = !dentry->d_inode ? -ENOENT :
2738 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2742 SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
2744 if ((flag & ~AT_REMOVEDIR) != 0)
2747 if (flag & AT_REMOVEDIR)
2748 return do_rmdir(dfd, pathname);
2750 return do_unlinkat(dfd, pathname);
2753 SYSCALL_DEFINE1(unlink, const char __user *, pathname)
2755 return do_unlinkat(AT_FDCWD, pathname);
2758 int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
2760 int error = may_create(dir, dentry);
2765 if (!dir->i_op->symlink)
2768 error = security_inode_symlink(dir, dentry, oldname);
2772 error = dir->i_op->symlink(dir, dentry, oldname);
2774 fsnotify_create(dir, dentry);
2778 SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
2779 int, newdfd, const char __user *, newname)
2783 struct dentry *dentry;
2786 from = getname(oldname);
2788 return PTR_ERR(from);
2790 dentry = user_path_create(newdfd, newname, &path, 0);
2791 error = PTR_ERR(dentry);
2795 error = mnt_want_write(path.mnt);
2798 error = security_path_symlink(&path, dentry, from);
2800 goto out_drop_write;
2801 error = vfs_symlink(path.dentry->d_inode, dentry, from);
2803 mnt_drop_write(path.mnt);
2806 mutex_unlock(&path.dentry->d_inode->i_mutex);
2813 SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
2815 return sys_symlinkat(oldname, AT_FDCWD, newname);
2818 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2820 struct inode *inode = old_dentry->d_inode;
2826 error = may_create(dir, new_dentry);
2830 if (dir->i_sb != inode->i_sb)
2834 * A link to an append-only or immutable file cannot be created.
2836 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2838 if (!dir->i_op->link)
2840 if (S_ISDIR(inode->i_mode))
2843 error = security_inode_link(old_dentry, dir, new_dentry);
2847 mutex_lock(&inode->i_mutex);
2848 /* Make sure we don't allow creating hardlink to an unlinked file */
2849 if (inode->i_nlink == 0)
2852 error = dir->i_op->link(old_dentry, dir, new_dentry);
2853 mutex_unlock(&inode->i_mutex);
2855 fsnotify_link(dir, inode, new_dentry);
2860 * Hardlinks are often used in delicate situations. We avoid
2861 * security-related surprises by not following symlinks on the
2864 * We don't follow them on the oldname either to be compatible
2865 * with linux 2.0, and to avoid hard-linking to directories
2866 * and other special files. --ADM
2868 SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
2869 int, newdfd, const char __user *, newname, int, flags)
2871 struct dentry *new_dentry;
2872 struct path old_path, new_path;
2876 if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
2879 * To use null names we require CAP_DAC_READ_SEARCH
2880 * This ensures that not everyone will be able to create
2881 * handlink using the passed filedescriptor.
2883 if (flags & AT_EMPTY_PATH) {
2884 if (!capable(CAP_DAC_READ_SEARCH))
2889 if (flags & AT_SYMLINK_FOLLOW)
2890 how |= LOOKUP_FOLLOW;
2892 error = user_path_at(olddfd, oldname, how, &old_path);
2896 new_dentry = user_path_create(newdfd, newname, &new_path, 0);
2897 error = PTR_ERR(new_dentry);
2898 if (IS_ERR(new_dentry))
2902 if (old_path.mnt != new_path.mnt)
2904 error = mnt_want_write(new_path.mnt);
2907 error = security_path_link(old_path.dentry, &new_path, new_dentry);
2909 goto out_drop_write;
2910 error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
2912 mnt_drop_write(new_path.mnt);
2915 mutex_unlock(&new_path.dentry->d_inode->i_mutex);
2916 path_put(&new_path);
2918 path_put(&old_path);
2923 SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
2925 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
2929 * The worst of all namespace operations - renaming directory. "Perverted"
2930 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2932 * a) we can get into loop creation. Check is done in is_subdir().
2933 * b) race potential - two innocent renames can create a loop together.
2934 * That's where 4.4 screws up. Current fix: serialization on
2935 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2937 * c) we have to lock _three_ objects - parents and victim (if it exists).
2938 * And that - after we got ->i_mutex on parents (until then we don't know
2939 * whether the target exists). Solution: try to be smart with locking
2940 * order for inodes. We rely on the fact that tree topology may change
2941 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2942 * move will be locked. Thus we can rank directories by the tree
2943 * (ancestors first) and rank all non-directories after them.
2944 * That works since everybody except rename does "lock parent, lookup,
2945 * lock child" and rename is under ->s_vfs_rename_mutex.
2946 * HOWEVER, it relies on the assumption that any object with ->lookup()
2947 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2948 * we'd better make sure that there's no link(2) for them.
2949 * d) conversion from fhandle to dentry may come in the wrong moment - when
2950 * we are removing the target. Solution: we will have to grab ->i_mutex
2951 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2952 * ->i_mutex on parents, which works but leads to some truly excessive
2955 static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2956 struct inode *new_dir, struct dentry *new_dentry)
2959 struct inode *target = new_dentry->d_inode;
2962 * If we are going to change the parent - check write permissions,
2963 * we'll need to flip '..'.
2965 if (new_dir != old_dir) {
2966 error = inode_permission(old_dentry->d_inode, MAY_WRITE);
2971 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2976 mutex_lock(&target->i_mutex);
2979 if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
2983 shrink_dcache_parent(new_dentry);
2984 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2989 target->i_flags |= S_DEAD;
2990 dont_mount(new_dentry);
2994 mutex_unlock(&target->i_mutex);
2996 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2997 d_move(old_dentry,new_dentry);
3001 static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
3002 struct inode *new_dir, struct dentry *new_dentry)
3004 struct inode *target = new_dentry->d_inode;
3007 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
3013 mutex_lock(&target->i_mutex);
3016 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
3019 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
3024 dont_mount(new_dentry);
3025 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
3026 d_move(old_dentry, new_dentry);
3029 mutex_unlock(&target->i_mutex);
3034 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
3035 struct inode *new_dir, struct dentry *new_dentry)
3038 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
3039 const unsigned char *old_name;
3041 if (old_dentry->d_inode == new_dentry->d_inode)
3044 error = may_delete(old_dir, old_dentry, is_dir);
3048 if (!new_dentry->d_inode)
3049 error = may_create(new_dir, new_dentry);
3051 error = may_delete(new_dir, new_dentry, is_dir);
3055 if (!old_dir->i_op->rename)
3058 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
3061 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
3063 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
3065 fsnotify_move(old_dir, new_dir, old_name, is_dir,
3066 new_dentry->d_inode, old_dentry);
3067 fsnotify_oldname_free(old_name);
3072 SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
3073 int, newdfd, const char __user *, newname)
3075 struct dentry *old_dir, *new_dir;
3076 struct dentry *old_dentry, *new_dentry;
3077 struct dentry *trap;
3078 struct nameidata oldnd, newnd;
3083 error = user_path_parent(olddfd, oldname, &oldnd, &from);
3087 error = user_path_parent(newdfd, newname, &newnd, &to);
3092 if (oldnd.path.mnt != newnd.path.mnt)
3095 old_dir = oldnd.path.dentry;
3097 if (oldnd.last_type != LAST_NORM)
3100 new_dir = newnd.path.dentry;
3101 if (newnd.last_type != LAST_NORM)
3104 oldnd.flags &= ~LOOKUP_PARENT;
3105 newnd.flags &= ~LOOKUP_PARENT;
3106 newnd.flags |= LOOKUP_RENAME_TARGET;
3108 trap = lock_rename(new_dir, old_dir);
3110 old_dentry = lookup_hash(&oldnd);
3111 error = PTR_ERR(old_dentry);
3112 if (IS_ERR(old_dentry))
3114 /* source must exist */
3116 if (!old_dentry->d_inode)
3118 /* unless the source is a directory trailing slashes give -ENOTDIR */
3119 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
3121 if (oldnd.last.name[oldnd.last.len])
3123 if (newnd.last.name[newnd.last.len])
3126 /* source should not be ancestor of target */
3128 if (old_dentry == trap)
3130 new_dentry = lookup_hash(&newnd);
3131 error = PTR_ERR(new_dentry);
3132 if (IS_ERR(new_dentry))
3134 /* target should not be an ancestor of source */
3136 if (new_dentry == trap)
3139 error = mnt_want_write(oldnd.path.mnt);
3142 error = security_path_rename(&oldnd.path, old_dentry,
3143 &newnd.path, new_dentry);
3146 error = vfs_rename(old_dir->d_inode, old_dentry,
3147 new_dir->d_inode, new_dentry);
3149 mnt_drop_write(oldnd.path.mnt);
3155 unlock_rename(new_dir, old_dir);
3157 path_put(&newnd.path);
3160 path_put(&oldnd.path);
3166 SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
3168 return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
3171 int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
3175 len = PTR_ERR(link);
3180 if (len > (unsigned) buflen)
3182 if (copy_to_user(buffer, link, len))
3189 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
3190 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
3191 * using) it for any given inode is up to filesystem.
3193 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3195 struct nameidata nd;
3200 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
3202 return PTR_ERR(cookie);
3204 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
3205 if (dentry->d_inode->i_op->put_link)
3206 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
3210 int vfs_follow_link(struct nameidata *nd, const char *link)
3212 return __vfs_follow_link(nd, link);
3215 /* get the link contents into pagecache */
3216 static char *page_getlink(struct dentry * dentry, struct page **ppage)
3220 struct address_space *mapping = dentry->d_inode->i_mapping;
3221 page = read_mapping_page(mapping, 0, NULL);
3226 nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
3230 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3232 struct page *page = NULL;
3233 char *s = page_getlink(dentry, &page);
3234 int res = vfs_readlink(dentry,buffer,buflen,s);
3237 page_cache_release(page);
3242 void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
3244 struct page *page = NULL;
3245 nd_set_link(nd, page_getlink(dentry, &page));
3249 void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
3251 struct page *page = cookie;
3255 page_cache_release(page);
3260 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
3262 int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
3264 struct address_space *mapping = inode->i_mapping;
3269 unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
3271 flags |= AOP_FLAG_NOFS;
3274 err = pagecache_write_begin(NULL, mapping, 0, len-1,
3275 flags, &page, &fsdata);
3279 kaddr = kmap_atomic(page, KM_USER0);
3280 memcpy(kaddr, symname, len-1);
3281 kunmap_atomic(kaddr, KM_USER0);
3283 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
3290 mark_inode_dirty(inode);
3296 int page_symlink(struct inode *inode, const char *symname, int len)
3298 return __page_symlink(inode, symname, len,
3299 !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
3302 const struct inode_operations page_symlink_inode_operations = {
3303 .readlink = generic_readlink,
3304 .follow_link = page_follow_link_light,
3305 .put_link = page_put_link,
3308 EXPORT_SYMBOL(user_path_at);
3309 EXPORT_SYMBOL(follow_down_one);
3310 EXPORT_SYMBOL(follow_down);
3311 EXPORT_SYMBOL(follow_up);
3312 EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
3313 EXPORT_SYMBOL(getname);
3314 EXPORT_SYMBOL(lock_rename);
3315 EXPORT_SYMBOL(lookup_one_len);
3316 EXPORT_SYMBOL(page_follow_link_light);
3317 EXPORT_SYMBOL(page_put_link);
3318 EXPORT_SYMBOL(page_readlink);
3319 EXPORT_SYMBOL(__page_symlink);
3320 EXPORT_SYMBOL(page_symlink);
3321 EXPORT_SYMBOL(page_symlink_inode_operations);
3322 EXPORT_SYMBOL(kern_path);
3323 EXPORT_SYMBOL(vfs_path_lookup);
3324 EXPORT_SYMBOL(inode_permission);
3325 EXPORT_SYMBOL(unlock_rename);
3326 EXPORT_SYMBOL(vfs_create);
3327 EXPORT_SYMBOL(vfs_follow_link);
3328 EXPORT_SYMBOL(vfs_link);
3329 EXPORT_SYMBOL(vfs_mkdir);
3330 EXPORT_SYMBOL(vfs_mknod);
3331 EXPORT_SYMBOL(generic_permission);
3332 EXPORT_SYMBOL(vfs_readlink);
3333 EXPORT_SYMBOL(vfs_rename);
3334 EXPORT_SYMBOL(vfs_rmdir);
3335 EXPORT_SYMBOL(vfs_symlink);
3336 EXPORT_SYMBOL(vfs_unlink);
3337 EXPORT_SYMBOL(dentry_unhash);
3338 EXPORT_SYMBOL(generic_readlink);