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