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);
238 if (S_ISDIR(inode->i_mode)) {
239 /* DACs are overridable for directories */
240 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
242 if (!(mask & MAY_WRITE))
243 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
248 * Read/write DACs are always overridable.
249 * Executable DACs are overridable when there is
250 * at least one exec bit set.
252 if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
253 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
257 * Searching includes executable on directories, else just read.
259 mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
260 if (mask == MAY_READ)
261 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
268 * inode_permission - check for access rights to a given inode
269 * @inode: inode to check permission on
270 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
272 * Used to check for read/write/execute permissions on an inode.
273 * We use "fsuid" for this, letting us set arbitrary permissions
274 * for filesystem access without changing the "normal" uids which
275 * are used for other things.
277 int inode_permission(struct inode *inode, int mask)
281 if (mask & MAY_WRITE) {
282 umode_t mode = inode->i_mode;
285 * Nobody gets write access to a read-only fs.
287 if (IS_RDONLY(inode) &&
288 (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
292 * Nobody gets write access to an immutable file.
294 if (IS_IMMUTABLE(inode))
298 if (inode->i_op->permission)
299 retval = inode->i_op->permission(inode, mask);
301 retval = generic_permission(inode, mask);
306 retval = devcgroup_inode_permission(inode, mask);
310 return security_inode_permission(inode, mask);
314 * path_get - get a reference to a path
315 * @path: path to get the reference to
317 * Given a path increment the reference count to the dentry and the vfsmount.
319 void path_get(struct path *path)
324 EXPORT_SYMBOL(path_get);
327 * path_put - put a reference to a path
328 * @path: path to put the reference to
330 * Given a path decrement the reference count to the dentry and the vfsmount.
332 void path_put(struct path *path)
337 EXPORT_SYMBOL(path_put);
340 * Path walking has 2 modes, rcu-walk and ref-walk (see
341 * Documentation/filesystems/path-lookup.txt). In situations when we can't
342 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
343 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
344 * mode. Refcounts are grabbed at the last known good point before rcu-walk
345 * got stuck, so ref-walk may continue from there. If this is not successful
346 * (eg. a seqcount has changed), then failure is returned and it's up to caller
347 * to restart the path walk from the beginning in ref-walk mode.
351 * unlazy_walk - try to switch to ref-walk mode.
352 * @nd: nameidata pathwalk data
353 * @dentry: child of nd->path.dentry or NULL
354 * Returns: 0 on success, -ECHILD on failure
356 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
357 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
358 * @nd or NULL. Must be called from rcu-walk context.
360 static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
362 struct fs_struct *fs = current->fs;
363 struct dentry *parent = nd->path.dentry;
366 BUG_ON(!(nd->flags & LOOKUP_RCU));
367 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
369 spin_lock(&fs->lock);
370 if (nd->root.mnt != fs->root.mnt ||
371 nd->root.dentry != fs->root.dentry)
374 spin_lock(&parent->d_lock);
376 if (!__d_rcu_to_refcount(parent, nd->seq))
378 BUG_ON(nd->inode != parent->d_inode);
380 if (dentry->d_parent != parent)
382 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
383 if (!__d_rcu_to_refcount(dentry, nd->seq))
386 * If the sequence check on the child dentry passed, then
387 * the child has not been removed from its parent. This
388 * means the parent dentry must be valid and able to take
389 * a reference at this point.
391 BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent);
392 BUG_ON(!parent->d_count);
394 spin_unlock(&dentry->d_lock);
396 spin_unlock(&parent->d_lock);
399 spin_unlock(&fs->lock);
401 mntget(nd->path.mnt);
404 br_read_unlock(vfsmount_lock);
405 nd->flags &= ~LOOKUP_RCU;
409 spin_unlock(&dentry->d_lock);
411 spin_unlock(&parent->d_lock);
414 spin_unlock(&fs->lock);
419 * release_open_intent - free up open intent resources
420 * @nd: pointer to nameidata
422 void release_open_intent(struct nameidata *nd)
424 struct file *file = nd->intent.open.file;
426 if (file && !IS_ERR(file)) {
427 if (file->f_path.dentry == NULL)
434 static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
436 return dentry->d_op->d_revalidate(dentry, nd);
440 * complete_walk - successful completion of path walk
441 * @nd: pointer nameidata
443 * If we had been in RCU mode, drop out of it and legitimize nd->path.
444 * Revalidate the final result, unless we'd already done that during
445 * the path walk or the filesystem doesn't ask for it. Return 0 on
446 * success, -error on failure. In case of failure caller does not
447 * need to drop nd->path.
449 static int complete_walk(struct nameidata *nd)
451 struct dentry *dentry = nd->path.dentry;
454 if (nd->flags & LOOKUP_RCU) {
455 nd->flags &= ~LOOKUP_RCU;
456 if (!(nd->flags & LOOKUP_ROOT))
458 spin_lock(&dentry->d_lock);
459 if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
460 spin_unlock(&dentry->d_lock);
462 br_read_unlock(vfsmount_lock);
465 BUG_ON(nd->inode != dentry->d_inode);
466 spin_unlock(&dentry->d_lock);
467 mntget(nd->path.mnt);
469 br_read_unlock(vfsmount_lock);
472 if (likely(!(nd->flags & LOOKUP_JUMPED)))
475 if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
478 if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
481 /* Note: we do not d_invalidate() */
482 status = d_revalidate(dentry, nd);
493 static __always_inline void set_root(struct nameidata *nd)
496 get_fs_root(current->fs, &nd->root);
499 static int link_path_walk(const char *, struct nameidata *);
501 static __always_inline void set_root_rcu(struct nameidata *nd)
504 struct fs_struct *fs = current->fs;
508 seq = read_seqcount_begin(&fs->seq);
510 nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
511 } while (read_seqcount_retry(&fs->seq, seq));
515 static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
527 nd->flags |= LOOKUP_JUMPED;
529 nd->inode = nd->path.dentry->d_inode;
531 ret = link_path_walk(link, nd);
535 return PTR_ERR(link);
538 static void path_put_conditional(struct path *path, struct nameidata *nd)
541 if (path->mnt != nd->path.mnt)
545 static inline void path_to_nameidata(const struct path *path,
546 struct nameidata *nd)
548 if (!(nd->flags & LOOKUP_RCU)) {
549 dput(nd->path.dentry);
550 if (nd->path.mnt != path->mnt)
551 mntput(nd->path.mnt);
553 nd->path.mnt = path->mnt;
554 nd->path.dentry = path->dentry;
557 static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
559 struct inode *inode = link->dentry->d_inode;
560 if (!IS_ERR(cookie) && inode->i_op->put_link)
561 inode->i_op->put_link(link->dentry, nd, cookie);
565 static __always_inline int
566 follow_link(struct path *link, struct nameidata *nd, void **p)
569 struct dentry *dentry = link->dentry;
571 BUG_ON(nd->flags & LOOKUP_RCU);
573 if (link->mnt == nd->path.mnt)
576 if (unlikely(current->total_link_count >= 40)) {
577 *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
582 current->total_link_count++;
584 touch_atime(link->mnt, dentry);
585 nd_set_link(nd, NULL);
587 error = security_inode_follow_link(link->dentry, nd);
589 *p = ERR_PTR(error); /* no ->put_link(), please */
594 nd->last_type = LAST_BIND;
595 *p = dentry->d_inode->i_op->follow_link(dentry, nd);
598 char *s = nd_get_link(nd);
601 error = __vfs_follow_link(nd, s);
602 else if (nd->last_type == LAST_BIND) {
603 nd->flags |= LOOKUP_JUMPED;
604 nd->inode = nd->path.dentry->d_inode;
605 if (nd->inode->i_op->follow_link) {
606 /* stepped on a _really_ weird one */
615 static int follow_up_rcu(struct path *path)
617 struct vfsmount *parent;
618 struct dentry *mountpoint;
620 parent = path->mnt->mnt_parent;
621 if (parent == path->mnt)
623 mountpoint = path->mnt->mnt_mountpoint;
624 path->dentry = mountpoint;
629 int follow_up(struct path *path)
631 struct vfsmount *parent;
632 struct dentry *mountpoint;
634 br_read_lock(vfsmount_lock);
635 parent = path->mnt->mnt_parent;
636 if (parent == path->mnt) {
637 br_read_unlock(vfsmount_lock);
641 mountpoint = dget(path->mnt->mnt_mountpoint);
642 br_read_unlock(vfsmount_lock);
644 path->dentry = mountpoint;
651 * Perform an automount
652 * - return -EISDIR to tell follow_managed() to stop and return the path we
655 static int follow_automount(struct path *path, unsigned flags,
658 struct vfsmount *mnt;
661 if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
664 /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT
665 * and this is the terminal part of the path.
667 if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_PARENT))
668 return -EISDIR; /* we actually want to stop here */
670 /* We want to mount if someone is trying to open/create a file of any
671 * type under the mountpoint, wants to traverse through the mountpoint
672 * or wants to open the mounted directory.
674 * We don't want to mount if someone's just doing a stat and they've
675 * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and
676 * appended a '/' to the name.
678 if (!(flags & LOOKUP_FOLLOW) &&
679 !(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
680 LOOKUP_OPEN | LOOKUP_CREATE)))
683 current->total_link_count++;
684 if (current->total_link_count >= 40)
687 mnt = path->dentry->d_op->d_automount(path);
690 * The filesystem is allowed to return -EISDIR here to indicate
691 * it doesn't want to automount. For instance, autofs would do
692 * this so that its userspace daemon can mount on this dentry.
694 * However, we can only permit this if it's a terminal point in
695 * the path being looked up; if it wasn't then the remainder of
696 * the path is inaccessible and we should say so.
698 if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT))
703 if (!mnt) /* mount collision */
707 /* lock_mount() may release path->mnt on error */
711 err = finish_automount(mnt, path);
715 /* Someone else made a mount here whilst we were busy */
720 path->dentry = dget(mnt->mnt_root);
729 * Handle a dentry that is managed in some way.
730 * - Flagged for transit management (autofs)
731 * - Flagged as mountpoint
732 * - Flagged as automount point
734 * This may only be called in refwalk mode.
736 * Serialization is taken care of in namespace.c
738 static int follow_managed(struct path *path, unsigned flags)
740 struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
742 bool need_mntput = false;
745 /* Given that we're not holding a lock here, we retain the value in a
746 * local variable for each dentry as we look at it so that we don't see
747 * the components of that value change under us */
748 while (managed = ACCESS_ONCE(path->dentry->d_flags),
749 managed &= DCACHE_MANAGED_DENTRY,
750 unlikely(managed != 0)) {
751 /* Allow the filesystem to manage the transit without i_mutex
753 if (managed & DCACHE_MANAGE_TRANSIT) {
754 BUG_ON(!path->dentry->d_op);
755 BUG_ON(!path->dentry->d_op->d_manage);
756 ret = path->dentry->d_op->d_manage(path->dentry, false);
761 /* Transit to a mounted filesystem. */
762 if (managed & DCACHE_MOUNTED) {
763 struct vfsmount *mounted = lookup_mnt(path);
769 path->dentry = dget(mounted->mnt_root);
774 /* Something is mounted on this dentry in another
775 * namespace and/or whatever was mounted there in this
776 * namespace got unmounted before we managed to get the
780 /* Handle an automount point */
781 if (managed & DCACHE_NEED_AUTOMOUNT) {
782 ret = follow_automount(path, flags, &need_mntput);
788 /* We didn't change the current path point */
792 if (need_mntput && path->mnt == mnt)
799 int follow_down_one(struct path *path)
801 struct vfsmount *mounted;
803 mounted = lookup_mnt(path);
808 path->dentry = dget(mounted->mnt_root);
814 static inline bool managed_dentry_might_block(struct dentry *dentry)
816 return (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
817 dentry->d_op->d_manage(dentry, true) < 0);
821 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
822 * we meet a managed dentry that would need blocking.
824 static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
825 struct inode **inode)
828 struct vfsmount *mounted;
830 * Don't forget we might have a non-mountpoint managed dentry
831 * that wants to block transit.
833 if (unlikely(managed_dentry_might_block(path->dentry)))
836 if (!d_mountpoint(path->dentry))
839 mounted = __lookup_mnt(path->mnt, path->dentry, 1);
843 path->dentry = mounted->mnt_root;
844 nd->seq = read_seqcount_begin(&path->dentry->d_seq);
846 * Update the inode too. We don't need to re-check the
847 * dentry sequence number here after this d_inode read,
848 * because a mount-point is always pinned.
850 *inode = path->dentry->d_inode;
855 static void follow_mount_rcu(struct nameidata *nd)
857 while (d_mountpoint(nd->path.dentry)) {
858 struct vfsmount *mounted;
859 mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
862 nd->path.mnt = mounted;
863 nd->path.dentry = mounted->mnt_root;
864 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
868 static int follow_dotdot_rcu(struct nameidata *nd)
873 if (nd->path.dentry == nd->root.dentry &&
874 nd->path.mnt == nd->root.mnt) {
877 if (nd->path.dentry != nd->path.mnt->mnt_root) {
878 struct dentry *old = nd->path.dentry;
879 struct dentry *parent = old->d_parent;
882 seq = read_seqcount_begin(&parent->d_seq);
883 if (read_seqcount_retry(&old->d_seq, nd->seq))
885 nd->path.dentry = parent;
889 if (!follow_up_rcu(&nd->path))
891 nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
893 follow_mount_rcu(nd);
894 nd->inode = nd->path.dentry->d_inode;
898 nd->flags &= ~LOOKUP_RCU;
899 if (!(nd->flags & LOOKUP_ROOT))
902 br_read_unlock(vfsmount_lock);
907 * Follow down to the covering mount currently visible to userspace. At each
908 * point, the filesystem owning that dentry may be queried as to whether the
909 * caller is permitted to proceed or not.
911 int follow_down(struct path *path)
916 while (managed = ACCESS_ONCE(path->dentry->d_flags),
917 unlikely(managed & DCACHE_MANAGED_DENTRY)) {
918 /* Allow the filesystem to manage the transit without i_mutex
921 * We indicate to the filesystem if someone is trying to mount
922 * something here. This gives autofs the chance to deny anyone
923 * other than its daemon the right to mount on its
926 * The filesystem may sleep at this point.
928 if (managed & DCACHE_MANAGE_TRANSIT) {
929 BUG_ON(!path->dentry->d_op);
930 BUG_ON(!path->dentry->d_op->d_manage);
931 ret = path->dentry->d_op->d_manage(
932 path->dentry, false);
934 return ret == -EISDIR ? 0 : ret;
937 /* Transit to a mounted filesystem. */
938 if (managed & DCACHE_MOUNTED) {
939 struct vfsmount *mounted = lookup_mnt(path);
945 path->dentry = dget(mounted->mnt_root);
949 /* Don't handle automount points here */
956 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
958 static void follow_mount(struct path *path)
960 while (d_mountpoint(path->dentry)) {
961 struct vfsmount *mounted = lookup_mnt(path);
967 path->dentry = dget(mounted->mnt_root);
971 static void follow_dotdot(struct nameidata *nd)
976 struct dentry *old = nd->path.dentry;
978 if (nd->path.dentry == nd->root.dentry &&
979 nd->path.mnt == nd->root.mnt) {
982 if (nd->path.dentry != nd->path.mnt->mnt_root) {
983 /* rare case of legitimate dget_parent()... */
984 nd->path.dentry = dget_parent(nd->path.dentry);
988 if (!follow_up(&nd->path))
991 follow_mount(&nd->path);
992 nd->inode = nd->path.dentry->d_inode;
996 * Allocate a dentry with name and parent, and perform a parent
997 * directory ->lookup on it. Returns the new dentry, or ERR_PTR
998 * on error. parent->d_inode->i_mutex must be held. d_lookup must
999 * have verified that no child exists while under i_mutex.
1001 static struct dentry *d_alloc_and_lookup(struct dentry *parent,
1002 struct qstr *name, struct nameidata *nd)
1004 struct inode *inode = parent->d_inode;
1005 struct dentry *dentry;
1008 /* Don't create child dentry for a dead directory. */
1009 if (unlikely(IS_DEADDIR(inode)))
1010 return ERR_PTR(-ENOENT);
1012 dentry = d_alloc(parent, name);
1013 if (unlikely(!dentry))
1014 return ERR_PTR(-ENOMEM);
1016 old = inode->i_op->lookup(inode, dentry, nd);
1017 if (unlikely(old)) {
1025 * We already have a dentry, but require a lookup to be performed on the parent
1026 * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error.
1027 * parent->d_inode->i_mutex must be held. d_lookup must have verified that no
1028 * child exists while under i_mutex.
1030 static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry,
1031 struct nameidata *nd)
1033 struct inode *inode = parent->d_inode;
1036 /* Don't create child dentry for a dead directory. */
1037 if (unlikely(IS_DEADDIR(inode)))
1038 return ERR_PTR(-ENOENT);
1040 old = inode->i_op->lookup(inode, dentry, nd);
1041 if (unlikely(old)) {
1049 * It's more convoluted than I'd like it to be, but... it's still fairly
1050 * small and for now I'd prefer to have fast path as straight as possible.
1051 * It _is_ time-critical.
1053 static int do_lookup(struct nameidata *nd, struct qstr *name,
1054 struct path *path, struct inode **inode)
1056 struct vfsmount *mnt = nd->path.mnt;
1057 struct dentry *dentry, *parent = nd->path.dentry;
1063 * Rename seqlock is not required here because in the off chance
1064 * of a false negative due to a concurrent rename, we're going to
1065 * do the non-racy lookup, below.
1067 if (nd->flags & LOOKUP_RCU) {
1070 dentry = __d_lookup_rcu(parent, name, &seq, inode);
1074 /* Memory barrier in read_seqcount_begin of child is enough */
1075 if (__read_seqcount_retry(&parent->d_seq, nd->seq))
1079 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
1080 status = d_revalidate(dentry, nd);
1081 if (unlikely(status <= 0)) {
1082 if (status != -ECHILD)
1087 if (unlikely(d_need_lookup(dentry)))
1090 path->dentry = dentry;
1091 if (unlikely(!__follow_mount_rcu(nd, path, inode)))
1093 if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
1097 if (unlazy_walk(nd, dentry))
1100 dentry = __d_lookup(parent, name);
1103 if (dentry && unlikely(d_need_lookup(dentry))) {
1108 if (unlikely(!dentry)) {
1109 struct inode *dir = parent->d_inode;
1110 BUG_ON(nd->inode != dir);
1112 mutex_lock(&dir->i_mutex);
1113 dentry = d_lookup(parent, name);
1114 if (likely(!dentry)) {
1115 dentry = d_alloc_and_lookup(parent, name, nd);
1116 if (IS_ERR(dentry)) {
1117 mutex_unlock(&dir->i_mutex);
1118 return PTR_ERR(dentry);
1123 } else if (unlikely(d_need_lookup(dentry))) {
1124 dentry = d_inode_lookup(parent, dentry, nd);
1125 if (IS_ERR(dentry)) {
1126 mutex_unlock(&dir->i_mutex);
1127 return PTR_ERR(dentry);
1133 mutex_unlock(&dir->i_mutex);
1135 if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
1136 status = d_revalidate(dentry, nd);
1137 if (unlikely(status <= 0)) {
1142 if (!d_invalidate(dentry)) {
1151 path->dentry = dentry;
1152 err = follow_managed(path, nd->flags);
1153 if (unlikely(err < 0)) {
1154 path_put_conditional(path, nd);
1157 *inode = path->dentry->d_inode;
1161 static inline int may_lookup(struct nameidata *nd)
1163 if (nd->flags & LOOKUP_RCU) {
1164 int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
1167 if (unlazy_walk(nd, NULL))
1170 return inode_permission(nd->inode, MAY_EXEC);
1173 static inline int handle_dots(struct nameidata *nd, int type)
1175 if (type == LAST_DOTDOT) {
1176 if (nd->flags & LOOKUP_RCU) {
1177 if (follow_dotdot_rcu(nd))
1185 static void terminate_walk(struct nameidata *nd)
1187 if (!(nd->flags & LOOKUP_RCU)) {
1188 path_put(&nd->path);
1190 nd->flags &= ~LOOKUP_RCU;
1191 if (!(nd->flags & LOOKUP_ROOT))
1192 nd->root.mnt = NULL;
1194 br_read_unlock(vfsmount_lock);
1198 static inline int walk_component(struct nameidata *nd, struct path *path,
1199 struct qstr *name, int type, int follow)
1201 struct inode *inode;
1204 * "." and ".." are special - ".." especially so because it has
1205 * to be able to know about the current root directory and
1206 * parent relationships.
1208 if (unlikely(type != LAST_NORM))
1209 return handle_dots(nd, type);
1210 err = do_lookup(nd, name, path, &inode);
1211 if (unlikely(err)) {
1216 path_to_nameidata(path, nd);
1220 if (unlikely(inode->i_op->follow_link) && follow) {
1221 if (nd->flags & LOOKUP_RCU) {
1222 if (unlikely(unlazy_walk(nd, path->dentry))) {
1227 BUG_ON(inode != path->dentry->d_inode);
1230 path_to_nameidata(path, nd);
1236 * This limits recursive symlink follows to 8, while
1237 * limiting consecutive symlinks to 40.
1239 * Without that kind of total limit, nasty chains of consecutive
1240 * symlinks can cause almost arbitrarily long lookups.
1242 static inline int nested_symlink(struct path *path, struct nameidata *nd)
1246 if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
1247 path_put_conditional(path, nd);
1248 path_put(&nd->path);
1251 BUG_ON(nd->depth >= MAX_NESTED_LINKS);
1254 current->link_count++;
1257 struct path link = *path;
1260 res = follow_link(&link, nd, &cookie);
1262 res = walk_component(nd, path, &nd->last,
1263 nd->last_type, LOOKUP_FOLLOW);
1264 put_link(nd, &link, cookie);
1267 current->link_count--;
1274 * This is the basic name resolution function, turning a pathname into
1275 * the final dentry. We expect 'base' to be positive and a directory.
1277 * Returns 0 and nd will have valid dentry and mnt on success.
1278 * Returns error and drops reference to input namei data on failure.
1280 static int link_path_walk(const char *name, struct nameidata *nd)
1290 /* At this point we know we have a real path component. */
1297 err = may_lookup(nd);
1302 c = *(const unsigned char *)name;
1304 hash = init_name_hash();
1307 hash = partial_name_hash(c, hash);
1308 c = *(const unsigned char *)name;
1309 } while (c && (c != '/'));
1310 this.len = name - (const char *) this.name;
1311 this.hash = end_name_hash(hash);
1314 if (this.name[0] == '.') switch (this.len) {
1316 if (this.name[1] == '.') {
1318 nd->flags |= LOOKUP_JUMPED;
1324 if (likely(type == LAST_NORM)) {
1325 struct dentry *parent = nd->path.dentry;
1326 nd->flags &= ~LOOKUP_JUMPED;
1327 if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
1328 err = parent->d_op->d_hash(parent, nd->inode,
1335 /* remove trailing slashes? */
1337 goto last_component;
1338 while (*++name == '/');
1340 goto last_component;
1342 err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW);
1347 err = nested_symlink(&next, nd);
1352 if (!nd->inode->i_op->lookup)
1355 /* here ends the main loop */
1359 nd->last_type = type;
1366 static int path_init(int dfd, const char *name, unsigned int flags,
1367 struct nameidata *nd, struct file **fp)
1373 nd->last_type = LAST_ROOT; /* if there are only slashes... */
1374 nd->flags = flags | LOOKUP_JUMPED;
1376 if (flags & LOOKUP_ROOT) {
1377 struct inode *inode = nd->root.dentry->d_inode;
1379 if (!inode->i_op->lookup)
1381 retval = inode_permission(inode, MAY_EXEC);
1385 nd->path = nd->root;
1387 if (flags & LOOKUP_RCU) {
1388 br_read_lock(vfsmount_lock);
1390 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1392 path_get(&nd->path);
1397 nd->root.mnt = NULL;
1400 if (flags & LOOKUP_RCU) {
1401 br_read_lock(vfsmount_lock);
1406 path_get(&nd->root);
1408 nd->path = nd->root;
1409 } else if (dfd == AT_FDCWD) {
1410 if (flags & LOOKUP_RCU) {
1411 struct fs_struct *fs = current->fs;
1414 br_read_lock(vfsmount_lock);
1418 seq = read_seqcount_begin(&fs->seq);
1420 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1421 } while (read_seqcount_retry(&fs->seq, seq));
1423 get_fs_pwd(current->fs, &nd->path);
1426 struct dentry *dentry;
1428 file = fget_raw_light(dfd, &fput_needed);
1433 dentry = file->f_path.dentry;
1437 if (!S_ISDIR(dentry->d_inode->i_mode))
1440 retval = inode_permission(dentry->d_inode, MAY_EXEC);
1445 nd->path = file->f_path;
1446 if (flags & LOOKUP_RCU) {
1449 nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
1450 br_read_lock(vfsmount_lock);
1453 path_get(&file->f_path);
1454 fput_light(file, fput_needed);
1458 nd->inode = nd->path.dentry->d_inode;
1462 fput_light(file, fput_needed);
1467 static inline int lookup_last(struct nameidata *nd, struct path *path)
1469 if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
1470 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
1472 nd->flags &= ~LOOKUP_PARENT;
1473 return walk_component(nd, path, &nd->last, nd->last_type,
1474 nd->flags & LOOKUP_FOLLOW);
1477 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1478 static int path_lookupat(int dfd, const char *name,
1479 unsigned int flags, struct nameidata *nd)
1481 struct file *base = NULL;
1486 * Path walking is largely split up into 2 different synchronisation
1487 * schemes, rcu-walk and ref-walk (explained in
1488 * Documentation/filesystems/path-lookup.txt). These share much of the
1489 * path walk code, but some things particularly setup, cleanup, and
1490 * following mounts are sufficiently divergent that functions are
1491 * duplicated. Typically there is a function foo(), and its RCU
1492 * analogue, foo_rcu().
1494 * -ECHILD is the error number of choice (just to avoid clashes) that
1495 * is returned if some aspect of an rcu-walk fails. Such an error must
1496 * be handled by restarting a traditional ref-walk (which will always
1497 * be able to complete).
1499 err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);
1504 current->total_link_count = 0;
1505 err = link_path_walk(name, nd);
1507 if (!err && !(flags & LOOKUP_PARENT)) {
1508 err = lookup_last(nd, &path);
1511 struct path link = path;
1512 nd->flags |= LOOKUP_PARENT;
1513 err = follow_link(&link, nd, &cookie);
1515 err = lookup_last(nd, &path);
1516 put_link(nd, &link, cookie);
1521 err = complete_walk(nd);
1523 if (!err && nd->flags & LOOKUP_DIRECTORY) {
1524 if (!nd->inode->i_op->lookup) {
1525 path_put(&nd->path);
1533 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
1534 path_put(&nd->root);
1535 nd->root.mnt = NULL;
1540 static int do_path_lookup(int dfd, const char *name,
1541 unsigned int flags, struct nameidata *nd)
1543 int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd);
1544 if (unlikely(retval == -ECHILD))
1545 retval = path_lookupat(dfd, name, flags, nd);
1546 if (unlikely(retval == -ESTALE))
1547 retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd);
1549 if (likely(!retval)) {
1550 if (unlikely(!audit_dummy_context())) {
1551 if (nd->path.dentry && nd->inode)
1552 audit_inode(name, nd->path.dentry);
1558 int kern_path_parent(const char *name, struct nameidata *nd)
1560 return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd);
1563 int kern_path(const char *name, unsigned int flags, struct path *path)
1565 struct nameidata nd;
1566 int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
1573 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1574 * @dentry: pointer to dentry of the base directory
1575 * @mnt: pointer to vfs mount of the base directory
1576 * @name: pointer to file name
1577 * @flags: lookup flags
1578 * @path: pointer to struct path to fill
1580 int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
1581 const char *name, unsigned int flags,
1584 struct nameidata nd;
1586 nd.root.dentry = dentry;
1588 BUG_ON(flags & LOOKUP_PARENT);
1589 /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
1590 err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd);
1596 static struct dentry *__lookup_hash(struct qstr *name,
1597 struct dentry *base, struct nameidata *nd)
1599 struct inode *inode = base->d_inode;
1600 struct dentry *dentry;
1603 err = inode_permission(inode, MAY_EXEC);
1605 return ERR_PTR(err);
1608 * Don't bother with __d_lookup: callers are for creat as
1609 * well as unlink, so a lot of the time it would cost
1612 dentry = d_lookup(base, name);
1614 if (dentry && d_need_lookup(dentry)) {
1616 * __lookup_hash is called with the parent dir's i_mutex already
1617 * held, so we are good to go here.
1619 dentry = d_inode_lookup(base, dentry, nd);
1624 if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) {
1625 int status = d_revalidate(dentry, nd);
1626 if (unlikely(status <= 0)) {
1628 * The dentry failed validation.
1629 * If d_revalidate returned 0 attempt to invalidate
1630 * the dentry otherwise d_revalidate is asking us
1631 * to return a fail status.
1635 return ERR_PTR(status);
1636 } else if (!d_invalidate(dentry)) {
1644 dentry = d_alloc_and_lookup(base, name, nd);
1650 * Restricted form of lookup. Doesn't follow links, single-component only,
1651 * needs parent already locked. Doesn't follow mounts.
1654 static struct dentry *lookup_hash(struct nameidata *nd)
1656 return __lookup_hash(&nd->last, nd->path.dentry, nd);
1660 * lookup_one_len - filesystem helper to lookup single pathname component
1661 * @name: pathname component to lookup
1662 * @base: base directory to lookup from
1663 * @len: maximum length @len should be interpreted to
1665 * Note that this routine is purely a helper for filesystem usage and should
1666 * not be called by generic code. Also note that by using this function the
1667 * nameidata argument is passed to the filesystem methods and a filesystem
1668 * using this helper needs to be prepared for that.
1670 struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
1676 WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
1681 return ERR_PTR(-EACCES);
1683 hash = init_name_hash();
1685 c = *(const unsigned char *)name++;
1686 if (c == '/' || c == '\0')
1687 return ERR_PTR(-EACCES);
1688 hash = partial_name_hash(c, hash);
1690 this.hash = end_name_hash(hash);
1692 * See if the low-level filesystem might want
1693 * to use its own hash..
1695 if (base->d_flags & DCACHE_OP_HASH) {
1696 int err = base->d_op->d_hash(base, base->d_inode, &this);
1698 return ERR_PTR(err);
1701 return __lookup_hash(&this, base, NULL);
1704 int user_path_at(int dfd, const char __user *name, unsigned flags,
1707 struct nameidata nd;
1708 char *tmp = getname_flags(name, flags);
1709 int err = PTR_ERR(tmp);
1712 BUG_ON(flags & LOOKUP_PARENT);
1714 err = do_path_lookup(dfd, tmp, flags, &nd);
1722 static int user_path_parent(int dfd, const char __user *path,
1723 struct nameidata *nd, char **name)
1725 char *s = getname(path);
1731 error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
1741 * It's inline, so penalty for filesystems that don't use sticky bit is
1744 static inline int check_sticky(struct inode *dir, struct inode *inode)
1746 uid_t fsuid = current_fsuid();
1748 if (!(dir->i_mode & S_ISVTX))
1750 if (current_user_ns() != inode_userns(inode))
1752 if (inode->i_uid == fsuid)
1754 if (dir->i_uid == fsuid)
1758 return !ns_capable(inode_userns(inode), CAP_FOWNER);
1762 * Check whether we can remove a link victim from directory dir, check
1763 * whether the type of victim is right.
1764 * 1. We can't do it if dir is read-only (done in permission())
1765 * 2. We should have write and exec permissions on dir
1766 * 3. We can't remove anything from append-only dir
1767 * 4. We can't do anything with immutable dir (done in permission())
1768 * 5. If the sticky bit on dir is set we should either
1769 * a. be owner of dir, or
1770 * b. be owner of victim, or
1771 * c. have CAP_FOWNER capability
1772 * 6. If the victim is append-only or immutable we can't do antyhing with
1773 * links pointing to it.
1774 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1775 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1776 * 9. We can't remove a root or mountpoint.
1777 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1778 * nfs_async_unlink().
1780 static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
1784 if (!victim->d_inode)
1787 BUG_ON(victim->d_parent->d_inode != dir);
1788 audit_inode_child(victim, dir);
1790 error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
1795 if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
1796 IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
1799 if (!S_ISDIR(victim->d_inode->i_mode))
1801 if (IS_ROOT(victim))
1803 } else if (S_ISDIR(victim->d_inode->i_mode))
1805 if (IS_DEADDIR(dir))
1807 if (victim->d_flags & DCACHE_NFSFS_RENAMED)
1812 /* Check whether we can create an object with dentry child in directory
1814 * 1. We can't do it if child already exists (open has special treatment for
1815 * this case, but since we are inlined it's OK)
1816 * 2. We can't do it if dir is read-only (done in permission())
1817 * 3. We should have write and exec permissions on dir
1818 * 4. We can't do it if dir is immutable (done in permission())
1820 static inline int may_create(struct inode *dir, struct dentry *child)
1824 if (IS_DEADDIR(dir))
1826 return inode_permission(dir, MAY_WRITE | MAY_EXEC);
1830 * p1 and p2 should be directories on the same fs.
1832 struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
1837 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1841 mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1843 p = d_ancestor(p2, p1);
1845 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
1846 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
1850 p = d_ancestor(p1, p2);
1852 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1853 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1857 mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
1858 mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
1862 void unlock_rename(struct dentry *p1, struct dentry *p2)
1864 mutex_unlock(&p1->d_inode->i_mutex);
1866 mutex_unlock(&p2->d_inode->i_mutex);
1867 mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
1871 int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
1872 struct nameidata *nd)
1874 int error = may_create(dir, dentry);
1879 if (!dir->i_op->create)
1880 return -EACCES; /* shouldn't it be ENOSYS? */
1883 error = security_inode_create(dir, dentry, mode);
1886 error = dir->i_op->create(dir, dentry, mode, nd);
1888 fsnotify_create(dir, dentry);
1892 static int may_open(struct path *path, int acc_mode, int flag)
1894 struct dentry *dentry = path->dentry;
1895 struct inode *inode = dentry->d_inode;
1905 switch (inode->i_mode & S_IFMT) {
1909 if (acc_mode & MAY_WRITE)
1914 if (path->mnt->mnt_flags & MNT_NODEV)
1923 error = inode_permission(inode, acc_mode);
1928 * An append-only file must be opened in append mode for writing.
1930 if (IS_APPEND(inode)) {
1931 if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
1937 /* O_NOATIME can only be set by the owner or superuser */
1938 if (flag & O_NOATIME && !inode_owner_or_capable(inode))
1942 * Ensure there are no outstanding leases on the file.
1944 return break_lease(inode, flag);
1947 static int handle_truncate(struct file *filp)
1949 struct path *path = &filp->f_path;
1950 struct inode *inode = path->dentry->d_inode;
1951 int error = get_write_access(inode);
1955 * Refuse to truncate files with mandatory locks held on them.
1957 error = locks_verify_locked(inode);
1959 error = security_path_truncate(path);
1961 error = do_truncate(path->dentry, 0,
1962 ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
1965 put_write_access(inode);
1969 static inline int open_to_namei_flags(int flag)
1971 if ((flag & O_ACCMODE) == 3)
1977 * Handle the last step of open()
1979 static struct file *do_last(struct nameidata *nd, struct path *path,
1980 const struct open_flags *op, const char *pathname)
1982 struct dentry *dir = nd->path.dentry;
1983 struct dentry *dentry;
1984 int open_flag = op->open_flag;
1985 int will_truncate = open_flag & O_TRUNC;
1987 int acc_mode = op->acc_mode;
1991 nd->flags &= ~LOOKUP_PARENT;
1992 nd->flags |= op->intent;
1994 switch (nd->last_type) {
1997 error = handle_dots(nd, nd->last_type);
1999 return ERR_PTR(error);
2002 error = complete_walk(nd);
2004 return ERR_PTR(error);
2005 audit_inode(pathname, nd->path.dentry);
2006 if (open_flag & O_CREAT) {
2012 error = complete_walk(nd);
2014 return ERR_PTR(error);
2015 audit_inode(pathname, dir);
2019 if (!(open_flag & O_CREAT)) {
2021 if (nd->last.name[nd->last.len])
2022 nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
2023 if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
2025 /* we _can_ be in RCU mode here */
2026 error = walk_component(nd, path, &nd->last, LAST_NORM,
2029 return ERR_PTR(error);
2030 if (error) /* symlink */
2033 error = complete_walk(nd);
2035 return ERR_PTR(-ECHILD);
2038 if (nd->flags & LOOKUP_DIRECTORY) {
2039 if (!nd->inode->i_op->lookup)
2042 audit_inode(pathname, nd->path.dentry);
2046 /* create side of things */
2047 error = complete_walk(nd);
2049 return ERR_PTR(error);
2051 audit_inode(pathname, dir);
2053 /* trailing slashes? */
2054 if (nd->last.name[nd->last.len])
2057 mutex_lock(&dir->d_inode->i_mutex);
2059 dentry = lookup_hash(nd);
2060 error = PTR_ERR(dentry);
2061 if (IS_ERR(dentry)) {
2062 mutex_unlock(&dir->d_inode->i_mutex);
2066 path->dentry = dentry;
2067 path->mnt = nd->path.mnt;
2069 /* Negative dentry, just create the file */
2070 if (!dentry->d_inode) {
2071 int mode = op->mode;
2072 if (!IS_POSIXACL(dir->d_inode))
2073 mode &= ~current_umask();
2075 * This write is needed to ensure that a
2076 * rw->ro transition does not occur between
2077 * the time when the file is created and when
2078 * a permanent write count is taken through
2079 * the 'struct file' in nameidata_to_filp().
2081 error = mnt_want_write(nd->path.mnt);
2083 goto exit_mutex_unlock;
2085 /* Don't check for write permission, don't truncate */
2086 open_flag &= ~O_TRUNC;
2088 acc_mode = MAY_OPEN;
2089 error = security_path_mknod(&nd->path, dentry, mode, 0);
2091 goto exit_mutex_unlock;
2092 error = vfs_create(dir->d_inode, dentry, mode, nd);
2094 goto exit_mutex_unlock;
2095 mutex_unlock(&dir->d_inode->i_mutex);
2096 dput(nd->path.dentry);
2097 nd->path.dentry = dentry;
2102 * It already exists.
2104 mutex_unlock(&dir->d_inode->i_mutex);
2105 audit_inode(pathname, path->dentry);
2108 if (open_flag & O_EXCL)
2111 error = follow_managed(path, nd->flags);
2116 if (!path->dentry->d_inode)
2119 if (path->dentry->d_inode->i_op->follow_link)
2122 path_to_nameidata(path, nd);
2123 nd->inode = path->dentry->d_inode;
2125 if (S_ISDIR(nd->inode->i_mode))
2128 if (!S_ISREG(nd->inode->i_mode))
2131 if (will_truncate) {
2132 error = mnt_want_write(nd->path.mnt);
2138 error = may_open(&nd->path, acc_mode, open_flag);
2141 filp = nameidata_to_filp(nd);
2142 if (!IS_ERR(filp)) {
2143 error = ima_file_check(filp, op->acc_mode);
2146 filp = ERR_PTR(error);
2149 if (!IS_ERR(filp)) {
2150 if (will_truncate) {
2151 error = handle_truncate(filp);
2154 filp = ERR_PTR(error);
2160 mnt_drop_write(nd->path.mnt);
2161 path_put(&nd->path);
2165 mutex_unlock(&dir->d_inode->i_mutex);
2167 path_put_conditional(path, nd);
2169 filp = ERR_PTR(error);
2173 static struct file *path_openat(int dfd, const char *pathname,
2174 struct nameidata *nd, const struct open_flags *op, int flags)
2176 struct file *base = NULL;
2181 filp = get_empty_filp();
2183 return ERR_PTR(-ENFILE);
2185 filp->f_flags = op->open_flag;
2186 nd->intent.open.file = filp;
2187 nd->intent.open.flags = open_to_namei_flags(op->open_flag);
2188 nd->intent.open.create_mode = op->mode;
2190 error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
2191 if (unlikely(error))
2194 current->total_link_count = 0;
2195 error = link_path_walk(pathname, nd);
2196 if (unlikely(error))
2199 filp = do_last(nd, &path, op, pathname);
2200 while (unlikely(!filp)) { /* trailing symlink */
2201 struct path link = path;
2203 if (!(nd->flags & LOOKUP_FOLLOW)) {
2204 path_put_conditional(&path, nd);
2205 path_put(&nd->path);
2206 filp = ERR_PTR(-ELOOP);
2209 nd->flags |= LOOKUP_PARENT;
2210 nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
2211 error = follow_link(&link, nd, &cookie);
2212 if (unlikely(error))
2213 filp = ERR_PTR(error);
2215 filp = do_last(nd, &path, op, pathname);
2216 put_link(nd, &link, cookie);
2219 if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))
2220 path_put(&nd->root);
2223 release_open_intent(nd);
2227 filp = ERR_PTR(error);
2231 struct file *do_filp_open(int dfd, const char *pathname,
2232 const struct open_flags *op, int flags)
2234 struct nameidata nd;
2237 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
2238 if (unlikely(filp == ERR_PTR(-ECHILD)))
2239 filp = path_openat(dfd, pathname, &nd, op, flags);
2240 if (unlikely(filp == ERR_PTR(-ESTALE)))
2241 filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL);
2245 struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
2246 const char *name, const struct open_flags *op, int flags)
2248 struct nameidata nd;
2252 nd.root.dentry = dentry;
2254 flags |= LOOKUP_ROOT;
2256 if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
2257 return ERR_PTR(-ELOOP);
2259 file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU);
2260 if (unlikely(file == ERR_PTR(-ECHILD)))
2261 file = path_openat(-1, name, &nd, op, flags);
2262 if (unlikely(file == ERR_PTR(-ESTALE)))
2263 file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL);
2267 struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
2269 struct dentry *dentry = ERR_PTR(-EEXIST);
2270 struct nameidata nd;
2271 int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
2273 return ERR_PTR(error);
2276 * Yucky last component or no last component at all?
2277 * (foo/., foo/.., /////)
2279 if (nd.last_type != LAST_NORM)
2281 nd.flags &= ~LOOKUP_PARENT;
2282 nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL;
2283 nd.intent.open.flags = O_EXCL;
2286 * Do the final lookup.
2288 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2289 dentry = lookup_hash(&nd);
2293 if (dentry->d_inode)
2296 * Special case - lookup gave negative, but... we had foo/bar/
2297 * From the vfs_mknod() POV we just have a negative dentry -
2298 * all is fine. Let's be bastards - you had / on the end, you've
2299 * been asking for (non-existent) directory. -ENOENT for you.
2301 if (unlikely(!is_dir && nd.last.name[nd.last.len])) {
2303 dentry = ERR_PTR(-ENOENT);
2310 dentry = ERR_PTR(-EEXIST);
2312 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2317 EXPORT_SYMBOL(kern_path_create);
2319 struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
2321 char *tmp = getname(pathname);
2324 return ERR_CAST(tmp);
2325 res = kern_path_create(dfd, tmp, path, is_dir);
2329 EXPORT_SYMBOL(user_path_create);
2331 int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
2333 int error = may_create(dir, dentry);
2338 if ((S_ISCHR(mode) || S_ISBLK(mode)) &&
2339 !ns_capable(inode_userns(dir), CAP_MKNOD))
2342 if (!dir->i_op->mknod)
2345 error = devcgroup_inode_mknod(mode, dev);
2349 error = security_inode_mknod(dir, dentry, mode, dev);
2353 error = dir->i_op->mknod(dir, dentry, mode, dev);
2355 fsnotify_create(dir, dentry);
2359 static int may_mknod(mode_t mode)
2361 switch (mode & S_IFMT) {
2367 case 0: /* zero mode translates to S_IFREG */
2376 SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
2379 struct dentry *dentry;
2386 dentry = user_path_create(dfd, filename, &path, 0);
2388 return PTR_ERR(dentry);
2390 if (!IS_POSIXACL(path.dentry->d_inode))
2391 mode &= ~current_umask();
2392 error = may_mknod(mode);
2395 error = mnt_want_write(path.mnt);
2398 error = security_path_mknod(&path, dentry, mode, dev);
2400 goto out_drop_write;
2401 switch (mode & S_IFMT) {
2402 case 0: case S_IFREG:
2403 error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
2405 case S_IFCHR: case S_IFBLK:
2406 error = vfs_mknod(path.dentry->d_inode,dentry,mode,
2407 new_decode_dev(dev));
2409 case S_IFIFO: case S_IFSOCK:
2410 error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
2414 mnt_drop_write(path.mnt);
2417 mutex_unlock(&path.dentry->d_inode->i_mutex);
2423 SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev)
2425 return sys_mknodat(AT_FDCWD, filename, mode, dev);
2428 int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
2430 int error = may_create(dir, dentry);
2435 if (!dir->i_op->mkdir)
2438 mode &= (S_IRWXUGO|S_ISVTX);
2439 error = security_inode_mkdir(dir, dentry, mode);
2443 error = dir->i_op->mkdir(dir, dentry, mode);
2445 fsnotify_mkdir(dir, dentry);
2449 SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode)
2451 struct dentry *dentry;
2455 dentry = user_path_create(dfd, pathname, &path, 1);
2457 return PTR_ERR(dentry);
2459 if (!IS_POSIXACL(path.dentry->d_inode))
2460 mode &= ~current_umask();
2461 error = mnt_want_write(path.mnt);
2464 error = security_path_mkdir(&path, dentry, mode);
2466 goto out_drop_write;
2467 error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
2469 mnt_drop_write(path.mnt);
2472 mutex_unlock(&path.dentry->d_inode->i_mutex);
2477 SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode)
2479 return sys_mkdirat(AT_FDCWD, pathname, mode);
2483 * The dentry_unhash() helper will try to drop the dentry early: we
2484 * should have a usage count of 2 if we're the only user of this
2485 * dentry, and if that is true (possibly after pruning the dcache),
2486 * then we drop the dentry now.
2488 * A low-level filesystem can, if it choses, legally
2491 * if (!d_unhashed(dentry))
2494 * if it cannot handle the case of removing a directory
2495 * that is still in use by something else..
2497 void dentry_unhash(struct dentry *dentry)
2499 shrink_dcache_parent(dentry);
2500 spin_lock(&dentry->d_lock);
2501 if (dentry->d_count == 1)
2503 spin_unlock(&dentry->d_lock);
2506 int vfs_rmdir(struct inode *dir, struct dentry *dentry)
2508 int error = may_delete(dir, dentry, 1);
2513 if (!dir->i_op->rmdir)
2516 mutex_lock(&dentry->d_inode->i_mutex);
2519 if (d_mountpoint(dentry))
2522 error = security_inode_rmdir(dir, dentry);
2526 shrink_dcache_parent(dentry);
2527 error = dir->i_op->rmdir(dir, dentry);
2531 dentry->d_inode->i_flags |= S_DEAD;
2535 mutex_unlock(&dentry->d_inode->i_mutex);
2541 static long do_rmdir(int dfd, const char __user *pathname)
2545 struct dentry *dentry;
2546 struct nameidata nd;
2548 error = user_path_parent(dfd, pathname, &nd, &name);
2552 switch(nd.last_type) {
2564 nd.flags &= ~LOOKUP_PARENT;
2566 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2567 dentry = lookup_hash(&nd);
2568 error = PTR_ERR(dentry);
2571 if (!dentry->d_inode) {
2575 error = mnt_want_write(nd.path.mnt);
2578 error = security_path_rmdir(&nd.path, dentry);
2581 error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
2583 mnt_drop_write(nd.path.mnt);
2587 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2594 SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
2596 return do_rmdir(AT_FDCWD, pathname);
2599 int vfs_unlink(struct inode *dir, struct dentry *dentry)
2601 int error = may_delete(dir, dentry, 0);
2606 if (!dir->i_op->unlink)
2609 mutex_lock(&dentry->d_inode->i_mutex);
2610 if (d_mountpoint(dentry))
2613 error = security_inode_unlink(dir, dentry);
2615 error = dir->i_op->unlink(dir, dentry);
2620 mutex_unlock(&dentry->d_inode->i_mutex);
2622 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2623 if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
2624 fsnotify_link_count(dentry->d_inode);
2632 * Make sure that the actual truncation of the file will occur outside its
2633 * directory's i_mutex. Truncate can take a long time if there is a lot of
2634 * writeout happening, and we don't want to prevent access to the directory
2635 * while waiting on the I/O.
2637 static long do_unlinkat(int dfd, const char __user *pathname)
2641 struct dentry *dentry;
2642 struct nameidata nd;
2643 struct inode *inode = NULL;
2645 error = user_path_parent(dfd, pathname, &nd, &name);
2650 if (nd.last_type != LAST_NORM)
2653 nd.flags &= ~LOOKUP_PARENT;
2655 mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
2656 dentry = lookup_hash(&nd);
2657 error = PTR_ERR(dentry);
2658 if (!IS_ERR(dentry)) {
2659 /* Why not before? Because we want correct error value */
2660 if (nd.last.name[nd.last.len])
2662 inode = dentry->d_inode;
2666 error = mnt_want_write(nd.path.mnt);
2669 error = security_path_unlink(&nd.path, dentry);
2672 error = vfs_unlink(nd.path.dentry->d_inode, dentry);
2674 mnt_drop_write(nd.path.mnt);
2678 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2680 iput(inode); /* truncate the inode here */
2687 error = !dentry->d_inode ? -ENOENT :
2688 S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
2692 SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
2694 if ((flag & ~AT_REMOVEDIR) != 0)
2697 if (flag & AT_REMOVEDIR)
2698 return do_rmdir(dfd, pathname);
2700 return do_unlinkat(dfd, pathname);
2703 SYSCALL_DEFINE1(unlink, const char __user *, pathname)
2705 return do_unlinkat(AT_FDCWD, pathname);
2708 int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
2710 int error = may_create(dir, dentry);
2715 if (!dir->i_op->symlink)
2718 error = security_inode_symlink(dir, dentry, oldname);
2722 error = dir->i_op->symlink(dir, dentry, oldname);
2724 fsnotify_create(dir, dentry);
2728 SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
2729 int, newdfd, const char __user *, newname)
2733 struct dentry *dentry;
2736 from = getname(oldname);
2738 return PTR_ERR(from);
2740 dentry = user_path_create(newdfd, newname, &path, 0);
2741 error = PTR_ERR(dentry);
2745 error = mnt_want_write(path.mnt);
2748 error = security_path_symlink(&path, dentry, from);
2750 goto out_drop_write;
2751 error = vfs_symlink(path.dentry->d_inode, dentry, from);
2753 mnt_drop_write(path.mnt);
2756 mutex_unlock(&path.dentry->d_inode->i_mutex);
2763 SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
2765 return sys_symlinkat(oldname, AT_FDCWD, newname);
2768 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
2770 struct inode *inode = old_dentry->d_inode;
2776 error = may_create(dir, new_dentry);
2780 if (dir->i_sb != inode->i_sb)
2784 * A link to an append-only or immutable file cannot be created.
2786 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2788 if (!dir->i_op->link)
2790 if (S_ISDIR(inode->i_mode))
2793 error = security_inode_link(old_dentry, dir, new_dentry);
2797 mutex_lock(&inode->i_mutex);
2798 /* Make sure we don't allow creating hardlink to an unlinked file */
2799 if (inode->i_nlink == 0)
2802 error = dir->i_op->link(old_dentry, dir, new_dentry);
2803 mutex_unlock(&inode->i_mutex);
2805 fsnotify_link(dir, inode, new_dentry);
2810 * Hardlinks are often used in delicate situations. We avoid
2811 * security-related surprises by not following symlinks on the
2814 * We don't follow them on the oldname either to be compatible
2815 * with linux 2.0, and to avoid hard-linking to directories
2816 * and other special files. --ADM
2818 SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
2819 int, newdfd, const char __user *, newname, int, flags)
2821 struct dentry *new_dentry;
2822 struct path old_path, new_path;
2826 if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
2829 * To use null names we require CAP_DAC_READ_SEARCH
2830 * This ensures that not everyone will be able to create
2831 * handlink using the passed filedescriptor.
2833 if (flags & AT_EMPTY_PATH) {
2834 if (!capable(CAP_DAC_READ_SEARCH))
2839 if (flags & AT_SYMLINK_FOLLOW)
2840 how |= LOOKUP_FOLLOW;
2842 error = user_path_at(olddfd, oldname, how, &old_path);
2846 new_dentry = user_path_create(newdfd, newname, &new_path, 0);
2847 error = PTR_ERR(new_dentry);
2848 if (IS_ERR(new_dentry))
2852 if (old_path.mnt != new_path.mnt)
2854 error = mnt_want_write(new_path.mnt);
2857 error = security_path_link(old_path.dentry, &new_path, new_dentry);
2859 goto out_drop_write;
2860 error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
2862 mnt_drop_write(new_path.mnt);
2865 mutex_unlock(&new_path.dentry->d_inode->i_mutex);
2866 path_put(&new_path);
2868 path_put(&old_path);
2873 SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
2875 return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
2879 * The worst of all namespace operations - renaming directory. "Perverted"
2880 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2882 * a) we can get into loop creation. Check is done in is_subdir().
2883 * b) race potential - two innocent renames can create a loop together.
2884 * That's where 4.4 screws up. Current fix: serialization on
2885 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2887 * c) we have to lock _three_ objects - parents and victim (if it exists).
2888 * And that - after we got ->i_mutex on parents (until then we don't know
2889 * whether the target exists). Solution: try to be smart with locking
2890 * order for inodes. We rely on the fact that tree topology may change
2891 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2892 * move will be locked. Thus we can rank directories by the tree
2893 * (ancestors first) and rank all non-directories after them.
2894 * That works since everybody except rename does "lock parent, lookup,
2895 * lock child" and rename is under ->s_vfs_rename_mutex.
2896 * HOWEVER, it relies on the assumption that any object with ->lookup()
2897 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2898 * we'd better make sure that there's no link(2) for them.
2899 * d) conversion from fhandle to dentry may come in the wrong moment - when
2900 * we are removing the target. Solution: we will have to grab ->i_mutex
2901 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2902 * ->i_mutex on parents, which works but leads to some truly excessive
2905 static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
2906 struct inode *new_dir, struct dentry *new_dentry)
2909 struct inode *target = new_dentry->d_inode;
2912 * If we are going to change the parent - check write permissions,
2913 * we'll need to flip '..'.
2915 if (new_dir != old_dir) {
2916 error = inode_permission(old_dentry->d_inode, MAY_WRITE);
2921 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2926 mutex_lock(&target->i_mutex);
2929 if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
2933 shrink_dcache_parent(new_dentry);
2934 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2939 target->i_flags |= S_DEAD;
2940 dont_mount(new_dentry);
2944 mutex_unlock(&target->i_mutex);
2946 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2947 d_move(old_dentry,new_dentry);
2951 static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
2952 struct inode *new_dir, struct dentry *new_dentry)
2954 struct inode *target = new_dentry->d_inode;
2957 error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
2963 mutex_lock(&target->i_mutex);
2966 if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
2969 error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
2974 dont_mount(new_dentry);
2975 if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
2976 d_move(old_dentry, new_dentry);
2979 mutex_unlock(&target->i_mutex);
2984 int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
2985 struct inode *new_dir, struct dentry *new_dentry)
2988 int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
2989 const unsigned char *old_name;
2991 if (old_dentry->d_inode == new_dentry->d_inode)
2994 error = may_delete(old_dir, old_dentry, is_dir);
2998 if (!new_dentry->d_inode)
2999 error = may_create(new_dir, new_dentry);
3001 error = may_delete(new_dir, new_dentry, is_dir);
3005 if (!old_dir->i_op->rename)
3008 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
3011 error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
3013 error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
3015 fsnotify_move(old_dir, new_dir, old_name, is_dir,
3016 new_dentry->d_inode, old_dentry);
3017 fsnotify_oldname_free(old_name);
3022 SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
3023 int, newdfd, const char __user *, newname)
3025 struct dentry *old_dir, *new_dir;
3026 struct dentry *old_dentry, *new_dentry;
3027 struct dentry *trap;
3028 struct nameidata oldnd, newnd;
3033 error = user_path_parent(olddfd, oldname, &oldnd, &from);
3037 error = user_path_parent(newdfd, newname, &newnd, &to);
3042 if (oldnd.path.mnt != newnd.path.mnt)
3045 old_dir = oldnd.path.dentry;
3047 if (oldnd.last_type != LAST_NORM)
3050 new_dir = newnd.path.dentry;
3051 if (newnd.last_type != LAST_NORM)
3054 oldnd.flags &= ~LOOKUP_PARENT;
3055 newnd.flags &= ~LOOKUP_PARENT;
3056 newnd.flags |= LOOKUP_RENAME_TARGET;
3058 trap = lock_rename(new_dir, old_dir);
3060 old_dentry = lookup_hash(&oldnd);
3061 error = PTR_ERR(old_dentry);
3062 if (IS_ERR(old_dentry))
3064 /* source must exist */
3066 if (!old_dentry->d_inode)
3068 /* unless the source is a directory trailing slashes give -ENOTDIR */
3069 if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
3071 if (oldnd.last.name[oldnd.last.len])
3073 if (newnd.last.name[newnd.last.len])
3076 /* source should not be ancestor of target */
3078 if (old_dentry == trap)
3080 new_dentry = lookup_hash(&newnd);
3081 error = PTR_ERR(new_dentry);
3082 if (IS_ERR(new_dentry))
3084 /* target should not be an ancestor of source */
3086 if (new_dentry == trap)
3089 error = mnt_want_write(oldnd.path.mnt);
3092 error = security_path_rename(&oldnd.path, old_dentry,
3093 &newnd.path, new_dentry);
3096 error = vfs_rename(old_dir->d_inode, old_dentry,
3097 new_dir->d_inode, new_dentry);
3099 mnt_drop_write(oldnd.path.mnt);
3105 unlock_rename(new_dir, old_dir);
3107 path_put(&newnd.path);
3110 path_put(&oldnd.path);
3116 SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
3118 return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
3121 int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
3125 len = PTR_ERR(link);
3130 if (len > (unsigned) buflen)
3132 if (copy_to_user(buffer, link, len))
3139 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
3140 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
3141 * using) it for any given inode is up to filesystem.
3143 int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3145 struct nameidata nd;
3150 cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
3152 return PTR_ERR(cookie);
3154 res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
3155 if (dentry->d_inode->i_op->put_link)
3156 dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
3160 int vfs_follow_link(struct nameidata *nd, const char *link)
3162 return __vfs_follow_link(nd, link);
3165 /* get the link contents into pagecache */
3166 static char *page_getlink(struct dentry * dentry, struct page **ppage)
3170 struct address_space *mapping = dentry->d_inode->i_mapping;
3171 page = read_mapping_page(mapping, 0, NULL);
3176 nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
3180 int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
3182 struct page *page = NULL;
3183 char *s = page_getlink(dentry, &page);
3184 int res = vfs_readlink(dentry,buffer,buflen,s);
3187 page_cache_release(page);
3192 void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
3194 struct page *page = NULL;
3195 nd_set_link(nd, page_getlink(dentry, &page));
3199 void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
3201 struct page *page = cookie;
3205 page_cache_release(page);
3210 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
3212 int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
3214 struct address_space *mapping = inode->i_mapping;
3219 unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
3221 flags |= AOP_FLAG_NOFS;
3224 err = pagecache_write_begin(NULL, mapping, 0, len-1,
3225 flags, &page, &fsdata);
3229 kaddr = kmap_atomic(page, KM_USER0);
3230 memcpy(kaddr, symname, len-1);
3231 kunmap_atomic(kaddr, KM_USER0);
3233 err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
3240 mark_inode_dirty(inode);
3246 int page_symlink(struct inode *inode, const char *symname, int len)
3248 return __page_symlink(inode, symname, len,
3249 !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
3252 const struct inode_operations page_symlink_inode_operations = {
3253 .readlink = generic_readlink,
3254 .follow_link = page_follow_link_light,
3255 .put_link = page_put_link,
3258 EXPORT_SYMBOL(user_path_at);
3259 EXPORT_SYMBOL(follow_down_one);
3260 EXPORT_SYMBOL(follow_down);
3261 EXPORT_SYMBOL(follow_up);
3262 EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
3263 EXPORT_SYMBOL(getname);
3264 EXPORT_SYMBOL(lock_rename);
3265 EXPORT_SYMBOL(lookup_one_len);
3266 EXPORT_SYMBOL(page_follow_link_light);
3267 EXPORT_SYMBOL(page_put_link);
3268 EXPORT_SYMBOL(page_readlink);
3269 EXPORT_SYMBOL(__page_symlink);
3270 EXPORT_SYMBOL(page_symlink);
3271 EXPORT_SYMBOL(page_symlink_inode_operations);
3272 EXPORT_SYMBOL(kern_path);
3273 EXPORT_SYMBOL(vfs_path_lookup);
3274 EXPORT_SYMBOL(inode_permission);
3275 EXPORT_SYMBOL(unlock_rename);
3276 EXPORT_SYMBOL(vfs_create);
3277 EXPORT_SYMBOL(vfs_follow_link);
3278 EXPORT_SYMBOL(vfs_link);
3279 EXPORT_SYMBOL(vfs_mkdir);
3280 EXPORT_SYMBOL(vfs_mknod);
3281 EXPORT_SYMBOL(generic_permission);
3282 EXPORT_SYMBOL(vfs_readlink);
3283 EXPORT_SYMBOL(vfs_rename);
3284 EXPORT_SYMBOL(vfs_rmdir);
3285 EXPORT_SYMBOL(vfs_symlink);
3286 EXPORT_SYMBOL(vfs_unlink);
3287 EXPORT_SYMBOL(dentry_unhash);
3288 EXPORT_SYMBOL(generic_readlink);