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 <asm/uaccess.h>
39 /* [Feb-1997 T. Schoebel-Theuer]
40 * Fundamental changes in the pathname lookup mechanisms (namei)
41 * were necessary because of omirr. The reason is that omirr needs
42 * to know the _real_ pathname, not the user-supplied one, in case
43 * of symlinks (and also when transname replacements occur).
45 * The new code replaces the old recursive symlink resolution with
46 * an iterative one (in case of non-nested symlink chains). It does
47 * this with calls to <fs>_follow_link().
48 * As a side effect, dir_namei(), _namei() and follow_link() are now
49 * replaced with a single function lookup_dentry() that can handle all
50 * the special cases of the former code.
52 * With the new dcache, the pathname is stored at each inode, at least as
53 * long as the refcount of the inode is positive. As a side effect, the
54 * size of the dcache depends on the inode cache and thus is dynamic.
56 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
57 * resolution to correspond with current state of the code.
59 * Note that the symlink resolution is not *completely* iterative.
60 * There is still a significant amount of tail- and mid- recursion in
61 * the algorithm. Also, note that <fs>_readlink() is not used in
62 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
63 * may return different results than <fs>_follow_link(). Many virtual
64 * filesystems (including /proc) exhibit this behavior.
67 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
68 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
69 * and the name already exists in form of a symlink, try to create the new
70 * name indicated by the symlink. The old code always complained that the
71 * name already exists, due to not following the symlink even if its target
72 * is nonexistent. The new semantics affects also mknod() and link() when
73 * the name is a symlink pointing to a non-existent name.
75 * I don't know which semantics is the right one, since I have no access
76 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
77 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
78 * "old" one. Personally, I think the new semantics is much more logical.
79 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
80 * file does succeed in both HP-UX and SunOs, but not in Solaris
81 * and in the old Linux semantics.
84 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
85 * semantics. See the comments in "open_namei" and "do_link" below.
87 * [10-Sep-98 Alan Modra] Another symlink change.
90 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
91 * inside the path - always follow.
92 * in the last component in creation/removal/renaming - never follow.
93 * if LOOKUP_FOLLOW passed - follow.
94 * if the pathname has trailing slashes - follow.
95 * otherwise - don't follow.
96 * (applied in that order).
98 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
99 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
100 * During the 2.4 we need to fix the userland stuff depending on it -
101 * hopefully we will be able to get rid of that wart in 2.5. So far only
102 * XEmacs seems to be relying on it...
105 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
106 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
107 * any extra contention...
110 /* In order to reduce some races, while at the same time doing additional
111 * checking and hopefully speeding things up, we copy filenames to the
112 * kernel data space before using them..
114 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
115 * PATH_MAX includes the nul terminator --RR.
117 static int do_getname(const char __user *filename, char *page)
120 unsigned long len = PATH_MAX;
122 if (!segment_eq(get_fs(), KERNEL_DS)) {
123 if ((unsigned long) filename >= TASK_SIZE)
125 if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
126 len = TASK_SIZE - (unsigned long) filename;
129 retval = strncpy_from_user(page, filename, len);
133 return -ENAMETOOLONG;
139 static char *getname_flags(const char __user * filename, int flags)
143 result = ERR_PTR(-ENOMEM);
146 int retval = do_getname(filename, tmp);
150 if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) {
152 result = ERR_PTR(retval);
156 audit_getname(result);
160 char *getname(const char __user * filename)
162 return getname_flags(filename, 0);
165 #ifdef CONFIG_AUDITSYSCALL
166 void putname(const char *name)
168 if (unlikely(!audit_dummy_context()))
173 EXPORT_SYMBOL(putname);
177 * This does basic POSIX ACL permission checking
179 static int acl_permission_check(struct inode *inode, int mask)
181 int (*check_acl)(struct inode *inode, int mask);
182 unsigned int mode = inode->i_mode;
184 mask &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
186 if (current_user_ns() != inode_userns(inode))
189 if (current_fsuid() == inode->i_uid)
192 check_acl = inode->i_op->check_acl;
193 if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
194 int error = check_acl(inode, mask);
195 if (error != -EAGAIN)
199 if (in_group_p(inode->i_gid))
205 * If the DACs are ok we don't need any capability check.
207 if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
213 * generic_permission - check for access rights on a Posix-like filesystem
214 * @inode: inode to check access rights for
215 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
216 * @flags: IPERM_FLAG_ flags.
218 * Used to check for read/write/execute permissions on a file.
219 * We use "fsuid" for this, letting us set arbitrary permissions
220 * for filesystem access without changing the "normal" uids which
221 * are used for other things.
223 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
224 * request cannot be satisfied (eg. requires blocking or too much complexity).
225 * It would then be called again in ref-walk mode.
227 int generic_permission(struct inode *inode, int mask)
232 * Do the basic POSIX ACL permission checks.
234 ret = acl_permission_check(inode, mask);
239 * Read/write DACs are always overridable.
240 * Executable DACs are overridable for all directories and
241 * for non-directories that have least one exec bit set.
243 if (!(mask & MAY_EXEC) || execute_ok(inode))
244 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
248 * Searching includes executable on directories, else just read.
250 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
251 if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
252 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
259 * inode_permission - check for access rights to a given inode
260 * @inode: inode to check permission on
261 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
263 * Used to check for read/write/execute permissions on an inode.
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 int inode_permission(struct inode *inode, int mask)
272 if (mask & MAY_WRITE) {
273 umode_t mode = inode->i_mode;
276 * Nobody gets write access to a read-only fs.
278 if (IS_RDONLY(inode) &&
279 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
283 * Nobody gets write access to an immutable file.
285 if (IS_IMMUTABLE(inode))
289 if (inode->i_op->permission)
290 retval = inode->i_op->permission(inode, mask, 0);
292 retval = generic_permission(inode, mask);
297 retval = devcgroup_inode_permission(inode, mask);
301 return security_inode_permission(inode, mask);
305 * exec_permission - check for right to do lookups in a given directory
306 * @inode: inode to check permission on
307 * @flags: IPERM_FLAG_ flags.
309 * Short-cut version of inode_permission(), for calling on directories
310 * during pathname resolution. Combines parts of inode_permission()
311 * and generic_permission(), and tests ONLY for MAY_EXEC permission.
313 * If appropriate, check DAC only. If not appropriate, or
314 * short-cut DAC fails, then call ->permission() to do more
315 * complete permission check.
317 static inline int exec_permission(struct inode *inode, unsigned int flags)
320 struct user_namespace *ns = inode_userns(inode);
322 if (flags & IPERM_FLAG_RCU)
323 mask |= MAY_NOT_BLOCK;
325 if (inode->i_op->permission) {
326 ret = inode->i_op->permission(inode, mask, flags);
330 ret = acl_permission_check(inode, mask);
335 if (ns_capable(ns, CAP_DAC_OVERRIDE) ||
336 ns_capable(ns, CAP_DAC_READ_SEARCH))
341 return security_inode_exec_permission(inode, flags);
345 * path_get - get a reference to a path
346 * @path: path to get the reference to
348 * Given a path increment the reference count to the dentry and the vfsmount.
350 void path_get(struct path *path)
355 EXPORT_SYMBOL(path_get);
358 * path_put - put a reference to a path
359 * @path: path to put the reference to
361 * Given a path decrement the reference count to the dentry and the vfsmount.
363 void path_put(struct path *path)
368 EXPORT_SYMBOL(path_put);
371 * Path walking has 2 modes, rcu-walk and ref-walk (see
372 * Documentation/filesystems/path-lookup.txt). In situations when we can't
373 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
374 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
375 * mode. Refcounts are grabbed at the last known good point before rcu-walk
376 * got stuck, so ref-walk may continue from there. If this is not successful
377 * (eg. a seqcount has changed), then failure is returned and it's up to caller
378 * to restart the path walk from the beginning in ref-walk mode.
382 * unlazy_walk - try to switch to ref-walk mode.
383 * @nd: nameidata pathwalk data
384 * @dentry: child of nd->path.dentry or NULL
385 * Returns: 0 on success, -ECHILD on failure
387 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
388 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
389 * @nd or NULL. Must be called from rcu-walk context.
391 static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
393 struct fs_struct *fs = current->fs;
394 struct dentry *parent = nd->path.dentry;
397 BUG_ON(!(nd->flags & LOOKUP_RCU));
398 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
400 spin_lock(&fs->lock);
401 if (nd->root.mnt != fs->root.mnt ||
402 nd->root.dentry != fs->root.dentry)
405 spin_lock(&parent->d_lock);
407 if (!__d_rcu_to_refcount(parent, nd->seq))
409 BUG_ON(nd->inode != parent->d_inode);
411 if (dentry->d_parent != parent)
413 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
414 if (!__d_rcu_to_refcount(dentry, nd->seq))
417 * If the sequence check on the child dentry passed, then
418 * the child has not been removed from its parent. This
419 * means the parent dentry must be valid and able to take
420 * a reference at this point.
422 BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent);
423 BUG_ON(!parent->d_count);
425 spin_unlock(&dentry->d_lock);
427 spin_unlock(&parent->d_lock);
430 spin_unlock(&fs->lock);
432 mntget(nd->path.mnt);
435 br_read_unlock(vfsmount_lock);
436 nd->flags &= ~LOOKUP_RCU;
440 spin_unlock(&dentry->d_lock);
442 spin_unlock(&parent->d_lock);
445 spin_unlock(&fs->lock);
450 * release_open_intent - free up open intent resources
451 * @nd: pointer to nameidata
453 void release_open_intent(struct nameidata *nd)
455 struct file *file = nd->intent.open.file;
457 if (file && !IS_ERR(file)) {
458 if (file->f_path.dentry == NULL)
465 static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
467 return dentry->d_op->d_revalidate(dentry, nd);
470 static struct dentry *
471 do_revalidate(struct dentry *dentry, struct nameidata *nd)
473 int status = d_revalidate(dentry, nd);
474 if (unlikely(status <= 0)) {
476 * The dentry failed validation.
477 * If d_revalidate returned 0 attempt to invalidate
478 * the dentry otherwise d_revalidate is asking us
479 * to return a fail status.
483 dentry = ERR_PTR(status);
484 } else if (!d_invalidate(dentry)) {
493 * complete_walk - successful completion of path walk
494 * @nd: pointer nameidata
496 * If we had been in RCU mode, drop out of it and legitimize nd->path.
497 * Revalidate the final result, unless we'd already done that during
498 * the path walk or the filesystem doesn't ask for it. Return 0 on
499 * success, -error on failure. In case of failure caller does not
500 * need to drop nd->path.
502 static int complete_walk(struct nameidata *nd)
504 struct dentry *dentry = nd->path.dentry;
507 if (nd->flags & LOOKUP_RCU) {
508 nd->flags &= ~LOOKUP_RCU;
509 if (!(nd->flags & LOOKUP_ROOT))
511 spin_lock(&dentry->d_lock);
512 if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
513 spin_unlock(&dentry->d_lock);
515 br_read_unlock(vfsmount_lock);
518 BUG_ON(nd->inode != dentry->d_inode);
519 spin_unlock(&dentry->d_lock);
520 mntget(nd->path.mnt);
522 br_read_unlock(vfsmount_lock);
525 if (likely(!(nd->flags & LOOKUP_JUMPED)))
528 if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
531 if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
534 /* Note: we do not d_invalidate() */
535 status = d_revalidate(dentry, nd);
546 static __always_inline void set_root(struct nameidata *nd)
549 get_fs_root(current->fs, &nd->root);
552 static int link_path_walk(const char *, struct nameidata *);
554 static __always_inline void set_root_rcu(struct nameidata *nd)
557 struct fs_struct *fs = current->fs;
561 seq = read_seqcount_begin(&fs->seq);
563 nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
564 } while (read_seqcount_retry(&fs->seq, seq));
568 static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
580 nd->flags |= LOOKUP_JUMPED;
582 nd->inode = nd->path.dentry->d_inode;
584 ret = link_path_walk(link, nd);
588 return PTR_ERR(link);
591 static void path_put_conditional(struct path *path, struct nameidata *nd)
594 if (path->mnt != nd->path.mnt)
598 static inline void path_to_nameidata(const struct path *path,
599 struct nameidata *nd)
601 if (!(nd->flags & LOOKUP_RCU)) {
602 dput(nd->path.dentry);
603 if (nd->path.mnt != path->mnt)
604 mntput(nd->path.mnt);
606 nd->path.mnt = path->mnt;
607 nd->path.dentry = path->dentry;
610 static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
612 struct inode *inode = link->dentry->d_inode;
613 if (!IS_ERR(cookie) && inode->i_op->put_link)
614 inode->i_op->put_link(link->dentry, nd, cookie);
618 static __always_inline int
619 follow_link(struct path *link, struct nameidata *nd, void **p)
622 struct dentry *dentry = link->dentry;
624 BUG_ON(nd->flags & LOOKUP_RCU);
626 if (link->mnt == nd->path.mnt)
629 if (unlikely(current->total_link_count >= 40)) {
630 *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
635 current->total_link_count++;
637 touch_atime(link->mnt, dentry);
638 nd_set_link(nd, NULL);
640 error = security_inode_follow_link(link->dentry, nd);
642 *p = ERR_PTR(error); /* no ->put_link(), please */
647 nd->last_type = LAST_BIND;
648 *p = dentry->d_inode->i_op->follow_link(dentry, nd);
651 char *s = nd_get_link(nd);
654 error = __vfs_follow_link(nd, s);
655 else if (nd->last_type == LAST_BIND) {
656 nd->flags |= LOOKUP_JUMPED;
657 nd->inode = nd->path.dentry->d_inode;
658 if (nd->inode->i_op->follow_link) {
659 /* stepped on a _really_ weird one */
668 static int follow_up_rcu(struct path *path)
670 struct vfsmount *parent;
671 struct dentry *mountpoint;
673 parent = path->mnt->mnt_parent;
674 if (parent == path->mnt)
676 mountpoint = path->mnt->mnt_mountpoint;
677 path->dentry = mountpoint;
682 int follow_up(struct path *path)
684 struct vfsmount *parent;
685 struct dentry *mountpoint;
687 br_read_lock(vfsmount_lock);
688 parent = path->mnt->mnt_parent;
689 if (parent == path->mnt) {
690 br_read_unlock(vfsmount_lock);
694 mountpoint = dget(path->mnt->mnt_mountpoint);
695 br_read_unlock(vfsmount_lock);
697 path->dentry = mountpoint;
704 * Perform an automount
705 * - return -EISDIR to tell follow_managed() to stop and return the path we
708 static int follow_automount(struct path *path, unsigned flags,
711 struct vfsmount *mnt;
714 if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
717 /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT
718 * and this is the terminal part of the path.
720 if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE))
721 return -EISDIR; /* we actually want to stop here */
723 /* We want to mount if someone is trying to open/create a file of any
724 * type under the mountpoint, wants to traverse through the mountpoint
725 * or wants to open the mounted directory.
727 * We don't want to mount if someone's just doing a stat and they've
728 * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and
729 * appended a '/' to the name.
731 if (!(flags & LOOKUP_FOLLOW) &&
732 !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY |
733 LOOKUP_OPEN | LOOKUP_CREATE)))
736 current->total_link_count++;
737 if (current->total_link_count >= 40)
740 mnt = path->dentry->d_op->d_automount(path);
743 * The filesystem is allowed to return -EISDIR here to indicate
744 * it doesn't want to automount. For instance, autofs would do
745 * this so that its userspace daemon can mount on this dentry.
747 * However, we can only permit this if it's a terminal point in
748 * the path being looked up; if it wasn't then the remainder of
749 * the path is inaccessible and we should say so.
751 if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE))
756 if (!mnt) /* mount collision */
760 /* lock_mount() may release path->mnt on error */
764 err = finish_automount(mnt, path);
768 /* Someone else made a mount here whilst we were busy */
773 path->dentry = dget(mnt->mnt_root);
782 * Handle a dentry that is managed in some way.
783 * - Flagged for transit management (autofs)
784 * - Flagged as mountpoint
785 * - Flagged as automount point
787 * This may only be called in refwalk mode.
789 * Serialization is taken care of in namespace.c
791 static int follow_managed(struct path *path, unsigned flags)
793 struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
795 bool need_mntput = false;
798 /* Given that we're not holding a lock here, we retain the value in a
799 * local variable for each dentry as we look at it so that we don't see
800 * the components of that value change under us */
801 while (managed = ACCESS_ONCE(path->dentry->d_flags),
802 managed &= DCACHE_MANAGED_DENTRY,
803 unlikely(managed != 0)) {
804 /* Allow the filesystem to manage the transit without i_mutex
806 if (managed & DCACHE_MANAGE_TRANSIT) {
807 BUG_ON(!path->dentry->d_op);
808 BUG_ON(!path->dentry->d_op->d_manage);
809 ret = path->dentry->d_op->d_manage(path->dentry, false);
814 /* Transit to a mounted filesystem. */
815 if (managed & DCACHE_MOUNTED) {
816 struct vfsmount *mounted = lookup_mnt(path);
822 path->dentry = dget(mounted->mnt_root);
827 /* Something is mounted on this dentry in another
828 * namespace and/or whatever was mounted there in this
829 * namespace got unmounted before we managed to get the
833 /* Handle an automount point */
834 if (managed & DCACHE_NEED_AUTOMOUNT) {
835 ret = follow_automount(path, flags, &need_mntput);
841 /* We didn't change the current path point */
845 if (need_mntput && path->mnt == mnt)
852 int follow_down_one(struct path *path)
854 struct vfsmount *mounted;
856 mounted = lookup_mnt(path);
861 path->dentry = dget(mounted->mnt_root);
867 static inline bool managed_dentry_might_block(struct dentry *dentry)
869 return (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
870 dentry->d_op->d_manage(dentry, true) < 0);
874 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
875 * we meet a managed dentry that would need blocking.
877 static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
878 struct inode **inode)
881 struct vfsmount *mounted;
883 * Don't forget we might have a non-mountpoint managed dentry
884 * that wants to block transit.
886 if (unlikely(managed_dentry_might_block(path->dentry)))
889 if (!d_mountpoint(path->dentry))
892 mounted = __lookup_mnt(path->mnt, path->dentry, 1);
896 path->dentry = mounted->mnt_root;
897 nd->seq = read_seqcount_begin(&path->dentry->d_seq);
899 * Update the inode too. We don't need to re-check the
900 * dentry sequence number here after this d_inode read,
901 * because a mount-point is always pinned.
903 *inode = path->dentry->d_inode;
908 static void follow_mount_rcu(struct nameidata *nd)
910 while (d_mountpoint(nd->path.dentry)) {
911 struct vfsmount *mounted;
912 mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
915 nd->path.mnt = mounted;
916 nd->path.dentry = mounted->mnt_root;
917 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
921 static int follow_dotdot_rcu(struct nameidata *nd)
926 if (nd->path.dentry == nd->root.dentry &&
927 nd->path.mnt == nd->root.mnt) {
930 if (nd->path.dentry != nd->path.mnt->mnt_root) {
931 struct dentry *old = nd->path.dentry;
932 struct dentry *parent = old->d_parent;
935 seq = read_seqcount_begin(&parent->d_seq);
936 if (read_seqcount_retry(&old->d_seq, nd->seq))
938 nd->path.dentry = parent;
942 if (!follow_up_rcu(&nd->path))
944 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
946 follow_mount_rcu(nd);
947 nd->inode = nd->path.dentry->d_inode;
951 nd->flags &= ~LOOKUP_RCU;
952 if (!(nd->flags & LOOKUP_ROOT))
955 br_read_unlock(vfsmount_lock);
960 * Follow down to the covering mount currently visible to userspace. At each
961 * point, the filesystem owning that dentry may be queried as to whether the
962 * caller is permitted to proceed or not.
964 int follow_down(struct path *path)
969 while (managed = ACCESS_ONCE(path->dentry->d_flags),
970 unlikely(managed & DCACHE_MANAGED_DENTRY)) {
971 /* Allow the filesystem to manage the transit without i_mutex
974 * We indicate to the filesystem if someone is trying to mount
975 * something here. This gives autofs the chance to deny anyone
976 * other than its daemon the right to mount on its
979 * The filesystem may sleep at this point.
981 if (managed & DCACHE_MANAGE_TRANSIT) {
982 BUG_ON(!path->dentry->d_op);
983 BUG_ON(!path->dentry->d_op->d_manage);
984 ret = path->dentry->d_op->d_manage(
985 path->dentry, false);
987 return ret == -EISDIR ? 0 : ret;
990 /* Transit to a mounted filesystem. */
991 if (managed & DCACHE_MOUNTED) {
992 struct vfsmount *mounted = lookup_mnt(path);
998 path->dentry = dget(mounted->mnt_root);
1002 /* Don't handle automount points here */
1009 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1011 static void follow_mount(struct path *path)
1013 while (d_mountpoint(path->dentry)) {
1014 struct vfsmount *mounted = lookup_mnt(path);
1019 path->mnt = mounted;
1020 path->dentry = dget(mounted->mnt_root);
1024 static void follow_dotdot(struct nameidata *nd)
1029 struct dentry *old = nd->path.dentry;
1031 if (nd->path.dentry == nd->root.dentry &&
1032 nd->path.mnt == nd->root.mnt) {
1035 if (nd->path.dentry != nd->path.mnt->mnt_root) {
1036 /* rare case of legitimate dget_parent()... */
1037 nd->path.dentry = dget_parent(nd->path.dentry);
1041 if (!follow_up(&nd->path))
1044 follow_mount(&nd->path);
1045 nd->inode = nd->path.dentry->d_inode;
1049 * Allocate a dentry with name and parent, and perform a parent
1050 * directory ->lookup on it. Returns the new dentry, or ERR_PTR
1051 * on error. parent->d_inode->i_mutex must be held. d_lookup must
1052 * have verified that no child exists while under i_mutex.
1054 static struct dentry *d_alloc_and_lookup(struct dentry *parent,
1055 struct qstr *name, struct nameidata *nd)
1057 struct inode *inode = parent->d_inode;
1058 struct dentry *dentry;
1061 /* Don't create child dentry for a dead directory. */
1062 if (unlikely(IS_DEADDIR(inode)))
1063 return ERR_PTR(-ENOENT);
1065 dentry = d_alloc(parent, name);
1066 if (unlikely(!dentry))
1067 return ERR_PTR(-ENOMEM);
1069 old = inode->i_op->lookup(inode, dentry, nd);
1070 if (unlikely(old)) {
1078 * We already have a dentry, but require a lookup to be performed on the parent
1079 * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error.
1080 * parent->d_inode->i_mutex must be held. d_lookup must have verified that no
1081 * child exists while under i_mutex.
1083 static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry,
1084 struct nameidata *nd)
1086 struct inode *inode = parent->d_inode;
1089 /* Don't create child dentry for a dead directory. */
1090 if (unlikely(IS_DEADDIR(inode)))
1091 return ERR_PTR(-ENOENT);
1093 old = inode->i_op->lookup(inode, dentry, nd);
1094 if (unlikely(old)) {
1102 * It's more convoluted than I'd like it to be, but... it's still fairly
1103 * small and for now I'd prefer to have fast path as straight as possible.
1104 * It _is_ time-critical.
1106 static int do_lookup(struct nameidata *nd, struct qstr *name,
1107 struct path *path, struct inode **inode)
1109 struct vfsmount *mnt = nd->path.mnt;
1110 struct dentry *dentry, *parent = nd->path.dentry;
1116 * Rename seqlock is not required here because in the off chance
1117 * of a false negative due to a concurrent rename, we're going to
1118 * do the non-racy lookup, below.
1120 if (nd->flags & LOOKUP_RCU) {
1123 dentry = __d_lookup_rcu(parent, name, &seq, inode);
1127 /* Memory barrier in read_seqcount_begin of child is enough */
1128 if (__read_seqcount_retry(&parent->d_seq, nd->seq))
1132 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
1133 status = d_revalidate(dentry, nd);
1134 if (unlikely(status <= 0)) {
1135 if (status != -ECHILD)
1140 if (unlikely(d_need_lookup(dentry)))
1143 path->dentry = dentry;
1144 if (unlikely(!__follow_mount_rcu(nd, path, inode)))
1146 if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
1150 if (unlazy_walk(nd, dentry))
1153 dentry = __d_lookup(parent, name);
1156 if (dentry && unlikely(d_need_lookup(dentry))) {
1161 if (unlikely(!dentry)) {
1162 struct inode *dir = parent->d_inode;
1163 BUG_ON(nd->inode != dir);
1165 mutex_lock(&dir->i_mutex);
1166 dentry = d_lookup(parent, name);
1167 if (likely(!dentry)) {
1168 dentry = d_alloc_and_lookup(parent, name, nd);
1169 if (IS_ERR(dentry)) {
1170 mutex_unlock(&dir->i_mutex);
1171 return PTR_ERR(dentry);
1176 } else if (unlikely(d_need_lookup(dentry))) {
1177 dentry = d_inode_lookup(parent, dentry, nd);
1178 if (IS_ERR(dentry)) {
1179 mutex_unlock(&dir->i_mutex);
1180 return PTR_ERR(dentry);
1186 mutex_unlock(&dir->i_mutex);
1188 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
1189 status = d_revalidate(dentry, nd);
1190 if (unlikely(status <= 0)) {
1195 if (!d_invalidate(dentry)) {
1204 path->dentry = dentry;
1205 err = follow_managed(path, nd->flags);
1206 if (unlikely(err < 0)) {
1207 path_put_conditional(path, nd);
1210 *inode = path->dentry->d_inode;
1214 static inline int may_lookup(struct nameidata *nd)
1216 if (nd->flags & LOOKUP_RCU) {
1217 int err = exec_permission(nd->inode, IPERM_FLAG_RCU);
1220 if (unlazy_walk(nd, NULL))
1223 return exec_permission(nd->inode, 0);
1226 static inline int handle_dots(struct nameidata *nd, int type)
1228 if (type == LAST_DOTDOT) {
1229 if (nd->flags & LOOKUP_RCU) {
1230 if (follow_dotdot_rcu(nd))
1238 static void terminate_walk(struct nameidata *nd)
1240 if (!(nd->flags & LOOKUP_RCU)) {
1241 path_put(&nd->path);
1243 nd->flags &= ~LOOKUP_RCU;
1244 if (!(nd->flags & LOOKUP_ROOT))
1245 nd->root.mnt = NULL;
1247 br_read_unlock(vfsmount_lock);
1251 static inline int walk_component(struct nameidata *nd, struct path *path,
1252 struct qstr *name, int type, int follow)
1254 struct inode *inode;
1257 * "." and ".." are special - ".." especially so because it has
1258 * to be able to know about the current root directory and
1259 * parent relationships.
1261 if (unlikely(type != LAST_NORM))
1262 return handle_dots(nd, type);
1263 err = do_lookup(nd, name, path, &inode);
1264 if (unlikely(err)) {
1269 path_to_nameidata(path, nd);
1273 if (unlikely(inode->i_op->follow_link) && follow) {
1274 if (nd->flags & LOOKUP_RCU) {
1275 if (unlikely(unlazy_walk(nd, path->dentry))) {
1280 BUG_ON(inode != path->dentry->d_inode);
1283 path_to_nameidata(path, nd);
1289 * This limits recursive symlink follows to 8, while
1290 * limiting consecutive symlinks to 40.
1292 * Without that kind of total limit, nasty chains of consecutive
1293 * symlinks can cause almost arbitrarily long lookups.
1295 static inline int nested_symlink(struct path *path, struct nameidata *nd)
1299 if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
1300 path_put_conditional(path, nd);
1301 path_put(&nd->path);
1304 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
1307 current->link_count++;
1310 struct path link = *path;
1313 res = follow_link(&link, nd, &cookie);
1315 res = walk_component(nd, path, &nd->last,
1316 nd->last_type, LOOKUP_FOLLOW);
1317 put_link(nd, &link, cookie);
1320 current->link_count--;
1327 * This is the basic name resolution function, turning a pathname into
1328 * the final dentry. We expect 'base' to be positive and a directory.
1330 * Returns 0 and nd will have valid dentry and mnt on success.
1331 * Returns error and drops reference to input namei data on failure.
1333 static int link_path_walk(const char *name, struct nameidata *nd)
1337 unsigned int lookup_flags = nd->flags;
1344 /* At this point we know we have a real path component. */
1351 nd->flags |= LOOKUP_CONTINUE;
1353 err = may_lookup(nd);
1358 c = *(const unsigned char *)name;
1360 hash = init_name_hash();
1363 hash = partial_name_hash(c, hash);
1364 c = *(const unsigned char *)name;
1365 } while (c && (c != '/'));
1366 this.len = name - (const char *) this.name;
1367 this.hash = end_name_hash(hash);
1370 if (this.name[0] == '.') switch (this.len) {
1372 if (this.name[1] == '.') {
1374 nd->flags |= LOOKUP_JUMPED;
1380 if (likely(type == LAST_NORM)) {
1381 struct dentry *parent = nd->path.dentry;
1382 nd->flags &= ~LOOKUP_JUMPED;
1383 if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
1384 err = parent->d_op->d_hash(parent, nd->inode,
1391 /* remove trailing slashes? */
1393 goto last_component;
1394 while (*++name == '/');
1396 goto last_component;
1398 err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW);
1403 err = nested_symlink(&next, nd);
1408 if (!nd->inode->i_op->lookup)
1411 /* here ends the main loop */
1414 /* Clear LOOKUP_CONTINUE iff it was previously unset */
1415 nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
1417 nd->last_type = type;
1424 static int path_init(int dfd, const char *name, unsigned int flags,
1425 struct nameidata *nd, struct file **fp)
1431 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1432 nd->flags = flags | LOOKUP_JUMPED;
1434 if (flags & LOOKUP_ROOT) {
1435 struct inode *inode = nd->root.dentry->d_inode;
1437 if (!inode->i_op->lookup)
1439 retval = inode_permission(inode, MAY_EXEC);
1443 nd->path = nd->root;
1445 if (flags & LOOKUP_RCU) {
1446 br_read_lock(vfsmount_lock);
1448 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1450 path_get(&nd->path);
1455 nd->root.mnt = NULL;
1458 if (flags & LOOKUP_RCU) {
1459 br_read_lock(vfsmount_lock);
1464 path_get(&nd->root);
1466 nd->path = nd->root;
1467 } else if (dfd == AT_FDCWD) {
1468 if (flags & LOOKUP_RCU) {
1469 struct fs_struct *fs = current->fs;
1472 br_read_lock(vfsmount_lock);
1476 seq = read_seqcount_begin(&fs->seq);
1478 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1479 } while (read_seqcount_retry(&fs->seq, seq));
1481 get_fs_pwd(current->fs, &nd->path);
1484 struct dentry *dentry;
1486 file = fget_raw_light(dfd, &fput_needed);
1491 dentry = file->f_path.dentry;
1495 if (!S_ISDIR(dentry->d_inode->i_mode))
1498 retval = exec_permission(dentry->d_inode, 0);
1503 nd->path = file->f_path;
1504 if (flags & LOOKUP_RCU) {
1507 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1508 br_read_lock(vfsmount_lock);
1511 path_get(&file->f_path);
1512 fput_light(file, fput_needed);
1516 nd->inode = nd->path.dentry->d_inode;
1520 fput_light(file, fput_needed);
1525 static inline int lookup_last(struct nameidata *nd, struct path *path)
1527 if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
1528 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
1530 nd->flags &= ~LOOKUP_PARENT;
1531 return walk_component(nd, path, &nd->last, nd->last_type,
1532 nd->flags & LOOKUP_FOLLOW);
1535 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1536 static int path_lookupat(int dfd, const char *name,
1537 unsigned int flags, struct nameidata *nd)
1539 struct file *base = NULL;
1544 * Path walking is largely split up into 2 different synchronisation
1545 * schemes, rcu-walk and ref-walk (explained in
1546 * Documentation/filesystems/path-lookup.txt). These share much of the
1547 * path walk code, but some things particularly setup, cleanup, and
1548 * following mounts are sufficiently divergent that functions are
1549 * duplicated. Typically there is a function foo(), and its RCU
1550 * analogue, foo_rcu().
1552 * -ECHILD is the error number of choice (just to avoid clashes) that
1553 * is returned if some aspect of an rcu-walk fails. Such an error must
1554 * be handled by restarting a traditional ref-walk (which will always
1555 * be able to complete).
1557 err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);
1562 current->total_link_count = 0;
1563 err = link_path_walk(name, nd);
1565 if (!err && !(flags & LOOKUP_PARENT)) {
1566 err = lookup_last(nd, &path);
1569 struct path link = path;
1570 nd->flags |= LOOKUP_PARENT;
1571 err = follow_link(&link, nd, &cookie);
1573 err = lookup_last(nd, &path);
1574 put_link(nd, &link, cookie);
1579 err = complete_walk(nd);
1581 if (!err && nd->flags & LOOKUP_DIRECTORY) {
1582 if (!nd->inode->i_op->lookup) {
1583 path_put(&nd->path);
1591 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
1592 path_put(&nd->root);
1593 nd->root.mnt = NULL;
1598 static int do_path_lookup(int dfd, const char *name,
1599 unsigned int flags, struct nameidata *nd)
1601 int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd);
1602 if (unlikely(retval == -ECHILD))
1603 retval = path_lookupat(dfd, name, flags, nd);
1604 if (unlikely(retval == -ESTALE))
1605 retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd);
1607 if (likely(!retval)) {
1608 if (unlikely(!audit_dummy_context())) {
1609 if (nd->path.dentry && nd->inode)
1610 audit_inode(name, nd->path.dentry);
1616 int kern_path_parent(const char *name, struct nameidata *nd)
1618 return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd);
1621 int kern_path(const char *name, unsigned int flags, struct path *path)
1623 struct nameidata nd;
1624 int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
1631 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1632 * @dentry: pointer to dentry of the base directory
1633 * @mnt: pointer to vfs mount of the base directory
1634 * @name: pointer to file name
1635 * @flags: lookup flags
1636 * @nd: pointer to nameidata
1638 int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
1639 const char *name, unsigned int flags,
1640 struct nameidata *nd)
1642 nd->root.dentry = dentry;
1644 /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
1645 return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd);
1648 static struct dentry *__lookup_hash(struct qstr *name,
1649 struct dentry *base, struct nameidata *nd)
1651 struct inode *inode = base->d_inode;
1652 struct dentry *dentry;
1655 err = exec_permission(inode, 0);
1657 return ERR_PTR(err);
1660 * Don't bother with __d_lookup: callers are for creat as
1661 * well as unlink, so a lot of the time it would cost
1664 dentry = d_lookup(base, name);
1666 if (dentry && d_need_lookup(dentry)) {
1668 * __lookup_hash is called with the parent dir's i_mutex already
1669 * held, so we are good to go here.
1671 dentry = d_inode_lookup(base, dentry, nd);
1676 if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE))
1677 dentry = do_revalidate(dentry, nd);
1680 dentry = d_alloc_and_lookup(base, name, nd);
1686 * Restricted form of lookup. Doesn't follow links, single-component only,
1687 * needs parent already locked. Doesn't follow mounts.
1690 static struct dentry *lookup_hash(struct nameidata *nd)
1692 return __lookup_hash(&nd->last, nd->path.dentry, nd);
1696 * lookup_one_len - filesystem helper to lookup single pathname component
1697 * @name: pathname component to lookup
1698 * @base: base directory to lookup from
1699 * @len: maximum length @len should be interpreted to
1701 * Note that this routine is purely a helper for filesystem usage and should
1702 * not be called by generic code. Also note that by using this function the
1703 * nameidata argument is passed to the filesystem methods and a filesystem
1704 * using this helper needs to be prepared for that.
1706 struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
1712 WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
1717 return ERR_PTR(-EACCES);
1719 hash = init_name_hash();
1721 c = *(const unsigned char *)name++;
1722 if (c == '/' || c == '\0')
1723 return ERR_PTR(-EACCES);
1724 hash = partial_name_hash(c, hash);
1726 this.hash = end_name_hash(hash);
1728 * See if the low-level filesystem might want
1729 * to use its own hash..
1731 if (base->d_flags & DCACHE_OP_HASH) {
1732 int err = base->d_op->d_hash(base, base->d_inode, &this);
1734 return ERR_PTR(err);
1737 return __lookup_hash(&this, base, NULL);
1740 int user_path_at(int dfd, const char __user *name, unsigned flags,
1743 struct nameidata nd;
1744 char *tmp = getname_flags(name, flags);
1745 int err = PTR_ERR(tmp);
1748 BUG_ON(flags & LOOKUP_PARENT);
1750 err = do_path_lookup(dfd, tmp, flags, &nd);
1758 static int user_path_parent(int dfd, const char __user *path,
1759 struct nameidata *nd, char **name)
1761 char *s = getname(path);
1767 error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
1777 * It's inline, so penalty for filesystems that don't use sticky bit is
1780 static inline int check_sticky(struct inode *dir, struct inode *inode)
1782 uid_t fsuid = current_fsuid();
1784 if (!(dir->i_mode & S_ISVTX))
1786 if (current_user_ns() != inode_userns(inode))
1788 if (inode->i_uid == fsuid)
1790 if (dir->i_uid == fsuid)
1794 return !ns_capable(inode_userns(inode), CAP_FOWNER);
1798 * Check whether we can remove a link victim from directory dir, check
1799 * whether the type of victim is right.
1800 * 1. We can't do it if dir is read-only (done in permission())
1801 * 2. We should have write and exec permissions on dir
1802 * 3. We can't remove anything from append-only dir
1803 * 4. We can't do anything with immutable dir (done in permission())
1804 * 5. If the sticky bit on dir is set we should either
1805 * a. be owner of dir, or
1806 * b. be owner of victim, or
1807 * c. have CAP_FOWNER capability
1808 * 6. If the victim is append-only or immutable we can't do antyhing with
1809 * links pointing to it.
1810 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1811 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1812 * 9. We can't remove a root or mountpoint.
1813 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1814 * nfs_async_unlink().
1816 static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1820 if (!victim->d_inode)
1823 BUG_ON(victim->d_parent->d_inode != dir);
1824 audit_inode_child(victim, dir);
1826 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
1831 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1832 IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
1835 if (!S_ISDIR(victim->d_inode->i_mode))
1837 if (IS_ROOT(victim))
1839 } else if (S_ISDIR(victim->d_inode->i_mode))
1841 if (IS_DEADDIR(dir))
1843 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1848 /* Check whether we can create an object with dentry child in directory
1850 * 1. We can't do it if child already exists (open has special treatment for
1851 * this case, but since we are inlined it's OK)
1852 * 2. We can't do it if dir is read-only (done in permission())
1853 * 3. We should have write and exec permissions on dir
1854 * 4. We can't do it if dir is immutable (done in permission())
1856 static inline int may_create(struct inode *dir, struct dentry *child)
1860 if (IS_DEADDIR(dir))
1862 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
1866 * p1 and p2 should be directories on the same fs.
1868 struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1873 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1877 mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1879 p = d_ancestor(p2, p1);
1881 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
1882 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
1886 p = d_ancestor(p1, p2);
1888 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1889 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1893 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1894 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1898 void unlock_rename(struct dentry *p1, struct dentry *p2)
1900 mutex_unlock(&p1->d_inode->i_mutex);
1902 mutex_unlock(&p2->d_inode->i_mutex);
1903 mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1907 int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1908 struct nameidata *nd)
1910 int error = may_create(dir, dentry);
1915 if (!dir->i_op->create)
1916 return -EACCES; /* shouldn't it be ENOSYS? */
1919 error = security_inode_create(dir, dentry, mode);
1922 error = dir->i_op->create(dir, dentry, mode, nd);
1924 fsnotify_create(dir, dentry);
1928 static int may_open(struct path *path, int acc_mode, int flag)
1930 struct dentry *dentry = path->dentry;
1931 struct inode *inode = dentry->d_inode;
1941 switch (inode->i_mode & S_IFMT) {
1945 if (acc_mode & MAY_WRITE)
1950 if (path->mnt->mnt_flags & MNT_NODEV)
1959 error = inode_permission(inode, acc_mode);
1964 * An append-only file must be opened in append mode for writing.
1966 if (IS_APPEND(inode)) {
1967 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
1973 /* O_NOATIME can only be set by the owner or superuser */
1974 if (flag & O_NOATIME && !inode_owner_or_capable(inode))
1978 * Ensure there are no outstanding leases on the file.
1980 return break_lease(inode, flag);
1983 static int handle_truncate(struct file *filp)
1985 struct path *path = &filp->f_path;
1986 struct inode *inode = path->dentry->d_inode;
1987 int error = get_write_access(inode);
1991 * Refuse to truncate files with mandatory locks held on them.
1993 error = locks_verify_locked(inode);
1995 error = security_path_truncate(path);
1997 error = do_truncate(path->dentry, 0,
1998 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
2001 put_write_access(inode);
2006 * Note that while the flag value (low two bits) for sys_open means:
2011 * it is changed into
2012 * 00 - no permissions needed
2013 * 01 - read-permission
2014 * 10 - write-permission
2016 * for the internal routines (ie open_namei()/follow_link() etc)
2017 * This is more logical, and also allows the 00 "no perm needed"
2018 * to be used for symlinks (where the permissions are checked
2022 static inline int open_to_namei_flags(int flag)
2024 if ((flag+1) & O_ACCMODE)
2030 * Handle the last step of open()
2032 static struct file *do_last(struct nameidata *nd, struct path *path,
2033 const struct open_flags *op, const char *pathname)
2035 struct dentry *dir = nd->path.dentry;
2036 struct dentry *dentry;
2037 int open_flag = op->open_flag;
2038 int will_truncate = open_flag & O_TRUNC;
2040 int acc_mode = op->acc_mode;
2044 nd->flags &= ~LOOKUP_PARENT;
2045 nd->flags |= op->intent;
2047 switch (nd->last_type) {
2050 error = handle_dots(nd, nd->last_type);
2052 return ERR_PTR(error);
2055 error = complete_walk(nd);
2057 return ERR_PTR(error);
2058 audit_inode(pathname, nd->path.dentry);
2059 if (open_flag & O_CREAT) {
2065 error = complete_walk(nd);
2067 return ERR_PTR(error);
2068 audit_inode(pathname, dir);
2072 if (!(open_flag & O_CREAT)) {
2074 if (nd->last.name[nd->last.len])
2075 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
2076 if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
2078 /* we _can_ be in RCU mode here */
2079 error = walk_component(nd, path, &nd->last, LAST_NORM,
2082 return ERR_PTR(error);
2083 if (error) /* symlink */
2086 error = complete_walk(nd);
2088 return ERR_PTR(-ECHILD);
2091 if (nd->flags & LOOKUP_DIRECTORY) {
2092 if (!nd->inode->i_op->lookup)
2095 audit_inode(pathname, nd->path.dentry);
2099 /* create side of things */
2100 error = complete_walk(nd);
2102 return ERR_PTR(error);
2104 audit_inode(pathname, dir);
2106 /* trailing slashes? */
2107 if (nd->last.name[nd->last.len])
2110 mutex_lock(&dir->d_inode->i_mutex);
2112 dentry = lookup_hash(nd);
2113 error = PTR_ERR(dentry);
2114 if (IS_ERR(dentry)) {
2115 mutex_unlock(&dir->d_inode->i_mutex);
2119 path->dentry = dentry;
2120 path->mnt = nd->path.mnt;
2122 /* Negative dentry, just create the file */
2123 if (!dentry->d_inode) {
2124 int mode = op->mode;
2125 if (!IS_POSIXACL(dir->d_inode))
2126 mode &= ~current_umask();
2128 * This write is needed to ensure that a
2129 * rw->ro transition does not occur between
2130 * the time when the file is created and when
2131 * a permanent write count is taken through
2132 * the 'struct file' in nameidata_to_filp().
2134 error = mnt_want_write(nd->path.mnt);
2136 goto exit_mutex_unlock;
2138 /* Don't check for write permission, don't truncate */
2139 open_flag &= ~O_TRUNC;
2141 acc_mode = MAY_OPEN;
2142 error = security_path_mknod(&nd->path, dentry, mode, 0);
2144 goto exit_mutex_unlock;
2145 error = vfs_create(dir->d_inode, dentry, mode, nd);
2147 goto exit_mutex_unlock;
2148 mutex_unlock(&dir->d_inode->i_mutex);
2149 dput(nd->path.dentry);
2150 nd->path.dentry = dentry;
2155 * It already exists.
2157 mutex_unlock(&dir->d_inode->i_mutex);
2158 audit_inode(pathname, path->dentry);
2161 if (open_flag & O_EXCL)
2164 error = follow_managed(path, nd->flags);
2169 if (!path->dentry->d_inode)
2172 if (path->dentry->d_inode->i_op->follow_link)
2175 path_to_nameidata(path, nd);
2176 nd->inode = path->dentry->d_inode;
2178 if (S_ISDIR(nd->inode->i_mode))
2181 if (!S_ISREG(nd->inode->i_mode))
2184 if (will_truncate) {
2185 error = mnt_want_write(nd->path.mnt);
2191 error = may_open(&nd->path, acc_mode, open_flag);
2194 filp = nameidata_to_filp(nd);
2195 if (!IS_ERR(filp)) {
2196 error = ima_file_check(filp, op->acc_mode);
2199 filp = ERR_PTR(error);
2202 if (!IS_ERR(filp)) {
2203 if (will_truncate) {
2204 error = handle_truncate(filp);
2207 filp = ERR_PTR(error);
2213 mnt_drop_write(nd->path.mnt);
2214 path_put(&nd->path);
2218 mutex_unlock(&dir->d_inode->i_mutex);
2220 path_put_conditional(path, nd);
2222 filp = ERR_PTR(error);
2226 static struct file *path_openat(int dfd, const char *pathname,
2227 struct nameidata *nd, const struct open_flags *op, int flags)
2229 struct file *base = NULL;
2234 filp = get_empty_filp();
2236 return ERR_PTR(-ENFILE);
2238 filp->f_flags = op->open_flag;
2239 nd->intent.open.file = filp;
2240 nd->intent.open.flags = open_to_namei_flags(op->open_flag);
2241 nd->intent.open.create_mode = op->mode;
2243 error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
2244 if (unlikely(error))
2247 current->total_link_count = 0;
2248 error = link_path_walk(pathname, nd);
2249 if (unlikely(error))
2252 filp = do_last(nd, &path, op, pathname);
2253 while (unlikely(!filp)) { /* trailing symlink */
2254 struct path link = path;
2256 if (!(nd->flags & LOOKUP_FOLLOW)) {
2257 path_put_conditional(&path, nd);
2258 path_put(&nd->path);
2259 filp = ERR_PTR(-ELOOP);
2262 nd->flags |= LOOKUP_PARENT;
2263 nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
2264 error = follow_link(&link, nd, &cookie);
2265 if (unlikely(error))
2266 filp = ERR_PTR(error);
2268 filp = do_last(nd, &path, op, pathname);
2269 put_link(nd, &link, cookie);
2272 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))
2273 path_put(&nd->root);
2276 release_open_intent(nd);
2280 filp = ERR_PTR(error);
2284 struct file *do_filp_open(int dfd, const char *pathname,
2285 const struct open_flags *op, int flags)
2287 struct nameidata nd;
2290 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
2291 if (unlikely(filp == ERR_PTR(-ECHILD)))
2292 filp = path_openat(dfd, pathname, &nd, op, flags);
2293 if (unlikely(filp == ERR_PTR(-ESTALE)))
2294 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL);
2298 struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
2299 const char *name, const struct open_flags *op, int flags)
2301 struct nameidata nd;
2305 nd.root.dentry = dentry;
2307 flags |= LOOKUP_ROOT;
2309 if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
2310 return ERR_PTR(-ELOOP);
2312 file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU);
2313 if (unlikely(file == ERR_PTR(-ECHILD)))
2314 file = path_openat(-1, name, &nd, op, flags);
2315 if (unlikely(file == ERR_PTR(-ESTALE)))
2316 file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL);
2321 * lookup_create - lookup a dentry, creating it if it doesn't exist
2322 * @nd: nameidata info
2323 * @is_dir: directory flag
2325 * Simple function to lookup and return a dentry and create it
2326 * if it doesn't exist. Is SMP-safe.
2328 * Returns with nd->path.dentry->d_inode->i_mutex locked.
2330 struct dentry *lookup_create(struct nameidata *nd, int is_dir)
2332 struct dentry *dentry = ERR_PTR(-EEXIST);
2334 mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2336 * Yucky last component or no last component at all?
2337 * (foo/., foo/.., /////)
2339 if (nd->last_type != LAST_NORM)
2341 nd->flags &= ~LOOKUP_PARENT;
2342 nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL;
2343 nd->intent.open.flags = O_EXCL;
2346 * Do the final lookup.
2348 dentry = lookup_hash(nd);
2352 if (dentry->d_inode)
2355 * Special case - lookup gave negative, but... we had foo/bar/
2356 * From the vfs_mknod() POV we just have a negative dentry -
2357 * all is fine. Let's be bastards - you had / on the end, you've
2358 * been asking for (non-existent) directory. -ENOENT for you.
2360 if (unlikely(!is_dir && nd->last.name[nd->last.len])) {
2362 dentry = ERR_PTR(-ENOENT);
2367 dentry = ERR_PTR(-EEXIST);
2371 EXPORT_SYMBOL_GPL(lookup_create);
2373 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
2375 int error = may_create(dir, dentry);
2380 if ((S_ISCHR(mode) || S_ISBLK(mode)) &&
2381 !ns_capable(inode_userns(dir), CAP_MKNOD))
2384 if (!dir->i_op->mknod)
2387 error = devcgroup_inode_mknod(mode, dev);
2391 error = security_inode_mknod(dir, dentry, mode, dev);
2395 error = dir->i_op->mknod(dir, dentry, mode, dev);
2397 fsnotify_create(dir, dentry);
2401 static int may_mknod(mode_t mode)
2403 switch (mode & S_IFMT) {
2409 case 0: /* zero mode translates to S_IFREG */
2418 SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
2423 struct dentry *dentry;
2424 struct nameidata nd;
2429 error = user_path_parent(dfd, filename, &nd, &tmp);
2433 dentry = lookup_create(&nd, 0);
2434 if (IS_ERR(dentry)) {
2435 error = PTR_ERR(dentry);
2438 if (!IS_POSIXACL(nd.path.dentry->d_inode))
2439 mode &= ~current_umask();
2440 error = may_mknod(mode);
2443 error = mnt_want_write(nd.path.mnt);
2446 error = security_path_mknod(&nd.path, dentry, mode, dev);
2448 goto out_drop_write;
2449 switch (mode & S_IFMT) {
2450 case 0: case S_IFREG:
2451 error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
2453 case S_IFCHR: case S_IFBLK:
2454 error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,
2455 new_decode_dev(dev));
2457 case S_IFIFO: case S_IFSOCK:
2458 error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
2462 mnt_drop_write(nd.path.mnt);
2466 mutex_unlock(&nd.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)
2503 struct dentry *dentry;
2504 struct nameidata nd;
2506 error = user_path_parent(dfd, pathname, &nd, &tmp);
2510 dentry = lookup_create(&nd, 1);
2511 error = PTR_ERR(dentry);
2515 if (!IS_POSIXACL(nd.path.dentry->d_inode))
2516 mode &= ~current_umask();
2517 error = mnt_want_write(nd.path.mnt);
2520 error = security_path_mkdir(&nd.path, dentry, mode);
2522 goto out_drop_write;
2523 error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
2525 mnt_drop_write(nd.path.mnt);
2529 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2536 SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode)
2538 return sys_mkdirat(AT_FDCWD, pathname, mode);
2542 * The dentry_unhash() helper will try to drop the dentry early: we
2543 * should have a usage count of 2 if we're the only user of this
2544 * dentry, and if that is true (possibly after pruning the dcache),
2545 * then we drop the dentry now.
2547 * A low-level filesystem can, if it choses, legally
2550 * if (!d_unhashed(dentry))
2553 * if it cannot handle the case of removing a directory
2554 * that is still in use by something else..
2556 void dentry_unhash(struct dentry *dentry)
2558 shrink_dcache_parent(dentry);
2559 spin_lock(&dentry->d_lock);
2560 if (dentry->d_count == 1)
2562 spin_unlock(&dentry->d_lock);
2565 int vfs_rmdir(struct inode *dir, struct dentry *dentry)
2567 int error = may_delete(dir, dentry, 1);
2572 if (!dir->i_op->rmdir)
2575 mutex_lock(&dentry->d_inode->i_mutex);
2578 if (d_mountpoint(dentry))
2581 error = security_inode_rmdir(dir, dentry);
2585 shrink_dcache_parent(dentry);
2586 error = dir->i_op->rmdir(dir, dentry);
2590 dentry->d_inode->i_flags |= S_DEAD;
2594 mutex_unlock(&dentry->d_inode->i_mutex);
2600 static long do_rmdir(int dfd, const char __user *pathname)
2604 struct dentry *dentry;
2605 struct nameidata nd;
2607 error = user_path_parent(dfd, pathname, &nd, &name);
2611 switch(nd.last_type) {
2623 nd.flags &= ~LOOKUP_PARENT;
2625 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2626 dentry = lookup_hash(&nd);
2627 error = PTR_ERR(dentry);
2630 if (!dentry->d_inode) {
2634 error = mnt_want_write(nd.path.mnt);
2637 error = security_path_rmdir(&nd.path, dentry);
2640 error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
2642 mnt_drop_write(nd.path.mnt);
2646 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2653 SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
2655 return do_rmdir(AT_FDCWD, pathname);
2658 int vfs_unlink(struct inode *dir, struct dentry *dentry)
2660 int error = may_delete(dir, dentry, 0);
2665 if (!dir->i_op->unlink)
2668 mutex_lock(&dentry->d_inode->i_mutex);
2669 if (d_mountpoint(dentry))
2672 error = security_inode_unlink(dir, dentry);
2674 error = dir->i_op->unlink(dir, dentry);
2679 mutex_unlock(&dentry->d_inode->i_mutex);
2681 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2682 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
2683 fsnotify_link_count(dentry->d_inode);
2691 * Make sure that the actual truncation of the file will occur outside its
2692 * directory's i_mutex. Truncate can take a long time if there is a lot of
2693 * writeout happening, and we don't want to prevent access to the directory
2694 * while waiting on the I/O.
2696 static long do_unlinkat(int dfd, const char __user *pathname)
2700 struct dentry *dentry;
2701 struct nameidata nd;
2702 struct inode *inode = NULL;
2704 error = user_path_parent(dfd, pathname, &nd, &name);
2709 if (nd.last_type != LAST_NORM)
2712 nd.flags &= ~LOOKUP_PARENT;
2714 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2715 dentry = lookup_hash(&nd);
2716 error = PTR_ERR(dentry);
2717 if (!IS_ERR(dentry)) {
2718 /* Why not before? Because we want correct error value */
2719 if (nd.last.name[nd.last.len])
2721 inode = dentry->d_inode;
2725 error = mnt_want_write(nd.path.mnt);
2728 error = security_path_unlink(&nd.path, dentry);
2731 error = vfs_unlink(nd.path.dentry->d_inode, dentry);
2733 mnt_drop_write(nd.path.mnt);
2737 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2739 iput(inode); /* truncate the inode here */
2746 error = !dentry->d_inode ? -ENOENT :
2747 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2751 SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
2753 if ((flag & ~AT_REMOVEDIR) != 0)
2756 if (flag & AT_REMOVEDIR)
2757 return do_rmdir(dfd, pathname);
2759 return do_unlinkat(dfd, pathname);
2762 SYSCALL_DEFINE1(unlink, const char __user *, pathname)
2764 return do_unlinkat(AT_FDCWD, pathname);
2767 int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
2769 int error = may_create(dir, dentry);
2774 if (!dir->i_op->symlink)
2777 error = security_inode_symlink(dir, dentry, oldname);
2781 error = dir->i_op->symlink(dir, dentry, oldname);
2783 fsnotify_create(dir, dentry);
2787 SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
2788 int, newdfd, const char __user *, newname)
2793 struct dentry *dentry;
2794 struct nameidata nd;
2796 from = getname(oldname);
2798 return PTR_ERR(from);
2800 error = user_path_parent(newdfd, newname, &nd, &to);
2804 dentry = lookup_create(&nd, 0);
2805 error = PTR_ERR(dentry);
2809 error = mnt_want_write(nd.path.mnt);
2812 error = security_path_symlink(&nd.path, dentry, from);
2814 goto out_drop_write;
2815 error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
2817 mnt_drop_write(nd.path.mnt);
2821 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2829 SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
2831 return sys_symlinkat(oldname, AT_FDCWD, newname);
2834 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2836 struct inode *inode = old_dentry->d_inode;
2842 error = may_create(dir, new_dentry);
2846 if (dir->i_sb != inode->i_sb)
2850 * A link to an append-only or immutable file cannot be created.
2852 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2854 if (!dir->i_op->link)
2856 if (S_ISDIR(inode->i_mode))
2859 error = security_inode_link(old_dentry, dir, new_dentry);
2863 mutex_lock(&inode->i_mutex);
2864 /* Make sure we don't allow creating hardlink to an unlinked file */
2865 if (inode->i_nlink == 0)
2868 error = dir->i_op->link(old_dentry, dir, new_dentry);
2869 mutex_unlock(&inode->i_mutex);
2871 fsnotify_link(dir, inode, new_dentry);
2876 * Hardlinks are often used in delicate situations. We avoid
2877 * security-related surprises by not following symlinks on the
2880 * We don't follow them on the oldname either to be compatible
2881 * with linux 2.0, and to avoid hard-linking to directories
2882 * and other special files. --ADM
2884 SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
2885 int, newdfd, const char __user *, newname, int, flags)
2887 struct dentry *new_dentry;
2888 struct nameidata nd;
2889 struct path old_path;
2894 if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
2897 * To use null names we require CAP_DAC_READ_SEARCH
2898 * This ensures that not everyone will be able to create
2899 * handlink using the passed filedescriptor.
2901 if (flags & AT_EMPTY_PATH) {
2902 if (!capable(CAP_DAC_READ_SEARCH))
2907 if (flags & AT_SYMLINK_FOLLOW)
2908 how |= LOOKUP_FOLLOW;
2910 error = user_path_at(olddfd, oldname, how, &old_path);
2914 error = user_path_parent(newdfd, newname, &nd, &to);
2918 if (old_path.mnt != nd.path.mnt)
2920 new_dentry = lookup_create(&nd, 0);
2921 error = PTR_ERR(new_dentry);
2922 if (IS_ERR(new_dentry))
2924 error = mnt_want_write(nd.path.mnt);
2927 error = security_path_link(old_path.dentry, &nd.path, new_dentry);
2929 goto out_drop_write;
2930 error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
2932 mnt_drop_write(nd.path.mnt);
2936 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2941 path_put(&old_path);
2946 SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
2948 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
2952 * The worst of all namespace operations - renaming directory. "Perverted"
2953 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2955 * a) we can get into loop creation. Check is done in is_subdir().
2956 * b) race potential - two innocent renames can create a loop together.
2957 * That's where 4.4 screws up. Current fix: serialization on
2958 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2960 * c) we have to lock _three_ objects - parents and victim (if it exists).
2961 * And that - after we got ->i_mutex on parents (until then we don't know
2962 * whether the target exists). Solution: try to be smart with locking
2963 * order for inodes. We rely on the fact that tree topology may change
2964 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2965 * move will be locked. Thus we can rank directories by the tree
2966 * (ancestors first) and rank all non-directories after them.
2967 * That works since everybody except rename does "lock parent, lookup,
2968 * lock child" and rename is under ->s_vfs_rename_mutex.
2969 * HOWEVER, it relies on the assumption that any object with ->lookup()
2970 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2971 * we'd better make sure that there's no link(2) for them.
2972 * d) conversion from fhandle to dentry may come in the wrong moment - when
2973 * we are removing the target. Solution: we will have to grab ->i_mutex
2974 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2975 * ->i_mutex on parents, which works but leads to some truly excessive
2978 static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2979 struct inode *new_dir, struct dentry *new_dentry)
2982 struct inode *target = new_dentry->d_inode;
2985 * If we are going to change the parent - check write permissions,
2986 * we'll need to flip '..'.
2988 if (new_dir != old_dir) {
2989 error = inode_permission(old_dentry->d_inode, MAY_WRITE);
2994 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2999 mutex_lock(&target->i_mutex);
3002 if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
3006 shrink_dcache_parent(new_dentry);
3007 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
3012 target->i_flags |= S_DEAD;
3013 dont_mount(new_dentry);
3017 mutex_unlock(&target->i_mutex);
3019 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
3020 d_move(old_dentry,new_dentry);
3024 static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
3025 struct inode *new_dir, struct dentry *new_dentry)
3027 struct inode *target = new_dentry->d_inode;
3030 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
3036 mutex_lock(&target->i_mutex);
3039 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
3042 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
3047 dont_mount(new_dentry);
3048 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
3049 d_move(old_dentry, new_dentry);
3052 mutex_unlock(&target->i_mutex);
3057 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
3058 struct inode *new_dir, struct dentry *new_dentry)
3061 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
3062 const unsigned char *old_name;
3064 if (old_dentry->d_inode == new_dentry->d_inode)
3067 error = may_delete(old_dir, old_dentry, is_dir);
3071 if (!new_dentry->d_inode)
3072 error = may_create(new_dir, new_dentry);
3074 error = may_delete(new_dir, new_dentry, is_dir);
3078 if (!old_dir->i_op->rename)
3081 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
3084 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
3086 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
3088 fsnotify_move(old_dir, new_dir, old_name, is_dir,
3089 new_dentry->d_inode, old_dentry);
3090 fsnotify_oldname_free(old_name);
3095 SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
3096 int, newdfd, const char __user *, newname)
3098 struct dentry *old_dir, *new_dir;
3099 struct dentry *old_dentry, *new_dentry;
3100 struct dentry *trap;
3101 struct nameidata oldnd, newnd;
3106 error = user_path_parent(olddfd, oldname, &oldnd, &from);
3110 error = user_path_parent(newdfd, newname, &newnd, &to);
3115 if (oldnd.path.mnt != newnd.path.mnt)
3118 old_dir = oldnd.path.dentry;
3120 if (oldnd.last_type != LAST_NORM)
3123 new_dir = newnd.path.dentry;
3124 if (newnd.last_type != LAST_NORM)
3127 oldnd.flags &= ~LOOKUP_PARENT;
3128 newnd.flags &= ~LOOKUP_PARENT;
3129 newnd.flags |= LOOKUP_RENAME_TARGET;
3131 trap = lock_rename(new_dir, old_dir);
3133 old_dentry = lookup_hash(&oldnd);
3134 error = PTR_ERR(old_dentry);
3135 if (IS_ERR(old_dentry))
3137 /* source must exist */
3139 if (!old_dentry->d_inode)
3141 /* unless the source is a directory trailing slashes give -ENOTDIR */
3142 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
3144 if (oldnd.last.name[oldnd.last.len])
3146 if (newnd.last.name[newnd.last.len])
3149 /* source should not be ancestor of target */
3151 if (old_dentry == trap)
3153 new_dentry = lookup_hash(&newnd);
3154 error = PTR_ERR(new_dentry);
3155 if (IS_ERR(new_dentry))
3157 /* target should not be an ancestor of source */
3159 if (new_dentry == trap)
3162 error = mnt_want_write(oldnd.path.mnt);
3165 error = security_path_rename(&oldnd.path, old_dentry,
3166 &newnd.path, new_dentry);
3169 error = vfs_rename(old_dir->d_inode, old_dentry,
3170 new_dir->d_inode, new_dentry);
3172 mnt_drop_write(oldnd.path.mnt);
3178 unlock_rename(new_dir, old_dir);
3180 path_put(&newnd.path);
3183 path_put(&oldnd.path);
3189 SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
3191 return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
3194 int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
3198 len = PTR_ERR(link);
3203 if (len > (unsigned) buflen)
3205 if (copy_to_user(buffer, link, len))
3212 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
3213 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
3214 * using) it for any given inode is up to filesystem.
3216 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3218 struct nameidata nd;
3223 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
3225 return PTR_ERR(cookie);
3227 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
3228 if (dentry->d_inode->i_op->put_link)
3229 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
3233 int vfs_follow_link(struct nameidata *nd, const char *link)
3235 return __vfs_follow_link(nd, link);
3238 /* get the link contents into pagecache */
3239 static char *page_getlink(struct dentry * dentry, struct page **ppage)
3243 struct address_space *mapping = dentry->d_inode->i_mapping;
3244 page = read_mapping_page(mapping, 0, NULL);
3249 nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
3253 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3255 struct page *page = NULL;
3256 char *s = page_getlink(dentry, &page);
3257 int res = vfs_readlink(dentry,buffer,buflen,s);
3260 page_cache_release(page);
3265 void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
3267 struct page *page = NULL;
3268 nd_set_link(nd, page_getlink(dentry, &page));
3272 void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
3274 struct page *page = cookie;
3278 page_cache_release(page);
3283 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
3285 int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
3287 struct address_space *mapping = inode->i_mapping;
3292 unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
3294 flags |= AOP_FLAG_NOFS;
3297 err = pagecache_write_begin(NULL, mapping, 0, len-1,
3298 flags, &page, &fsdata);
3302 kaddr = kmap_atomic(page, KM_USER0);
3303 memcpy(kaddr, symname, len-1);
3304 kunmap_atomic(kaddr, KM_USER0);
3306 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
3313 mark_inode_dirty(inode);
3319 int page_symlink(struct inode *inode, const char *symname, int len)
3321 return __page_symlink(inode, symname, len,
3322 !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
3325 const struct inode_operations page_symlink_inode_operations = {
3326 .readlink = generic_readlink,
3327 .follow_link = page_follow_link_light,
3328 .put_link = page_put_link,
3331 EXPORT_SYMBOL(user_path_at);
3332 EXPORT_SYMBOL(follow_down_one);
3333 EXPORT_SYMBOL(follow_down);
3334 EXPORT_SYMBOL(follow_up);
3335 EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
3336 EXPORT_SYMBOL(getname);
3337 EXPORT_SYMBOL(lock_rename);
3338 EXPORT_SYMBOL(lookup_one_len);
3339 EXPORT_SYMBOL(page_follow_link_light);
3340 EXPORT_SYMBOL(page_put_link);
3341 EXPORT_SYMBOL(page_readlink);
3342 EXPORT_SYMBOL(__page_symlink);
3343 EXPORT_SYMBOL(page_symlink);
3344 EXPORT_SYMBOL(page_symlink_inode_operations);
3345 EXPORT_SYMBOL(kern_path_parent);
3346 EXPORT_SYMBOL(kern_path);
3347 EXPORT_SYMBOL(vfs_path_lookup);
3348 EXPORT_SYMBOL(inode_permission);
3349 EXPORT_SYMBOL(unlock_rename);
3350 EXPORT_SYMBOL(vfs_create);
3351 EXPORT_SYMBOL(vfs_follow_link);
3352 EXPORT_SYMBOL(vfs_link);
3353 EXPORT_SYMBOL(vfs_mkdir);
3354 EXPORT_SYMBOL(vfs_mknod);
3355 EXPORT_SYMBOL(generic_permission);
3356 EXPORT_SYMBOL(vfs_readlink);
3357 EXPORT_SYMBOL(vfs_rename);
3358 EXPORT_SYMBOL(vfs_rmdir);
3359 EXPORT_SYMBOL(vfs_symlink);
3360 EXPORT_SYMBOL(vfs_unlink);
3361 EXPORT_SYMBOL(dentry_unhash);
3362 EXPORT_SYMBOL(generic_readlink);