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/export.h>
19 #include <linux/kernel.h>
20 #include <linux/slab.h>
22 #include <linux/namei.h>
23 #include <linux/pagemap.h>
24 #include <linux/fsnotify.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/ima.h>
28 #include <linux/syscalls.h>
29 #include <linux/mount.h>
30 #include <linux/audit.h>
31 #include <linux/capability.h>
32 #include <linux/file.h>
33 #include <linux/fcntl.h>
34 #include <linux/device_cgroup.h>
35 #include <linux/fs_struct.h>
36 #include <linux/posix_acl.h>
37 #include <asm/uaccess.h>
42 /* [Feb-1997 T. Schoebel-Theuer]
43 * Fundamental changes in the pathname lookup mechanisms (namei)
44 * were necessary because of omirr. The reason is that omirr needs
45 * to know the _real_ pathname, not the user-supplied one, in case
46 * of symlinks (and also when transname replacements occur).
48 * The new code replaces the old recursive symlink resolution with
49 * an iterative one (in case of non-nested symlink chains). It does
50 * this with calls to <fs>_follow_link().
51 * As a side effect, dir_namei(), _namei() and follow_link() are now
52 * replaced with a single function lookup_dentry() that can handle all
53 * the special cases of the former code.
55 * With the new dcache, the pathname is stored at each inode, at least as
56 * long as the refcount of the inode is positive. As a side effect, the
57 * size of the dcache depends on the inode cache and thus is dynamic.
59 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
60 * resolution to correspond with current state of the code.
62 * Note that the symlink resolution is not *completely* iterative.
63 * There is still a significant amount of tail- and mid- recursion in
64 * the algorithm. Also, note that <fs>_readlink() is not used in
65 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
66 * may return different results than <fs>_follow_link(). Many virtual
67 * filesystems (including /proc) exhibit this behavior.
70 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
71 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
72 * and the name already exists in form of a symlink, try to create the new
73 * name indicated by the symlink. The old code always complained that the
74 * name already exists, due to not following the symlink even if its target
75 * is nonexistent. The new semantics affects also mknod() and link() when
76 * the name is a symlink pointing to a non-existent name.
78 * I don't know which semantics is the right one, since I have no access
79 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
80 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
81 * "old" one. Personally, I think the new semantics is much more logical.
82 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
83 * file does succeed in both HP-UX and SunOs, but not in Solaris
84 * and in the old Linux semantics.
87 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
88 * semantics. See the comments in "open_namei" and "do_link" below.
90 * [10-Sep-98 Alan Modra] Another symlink change.
93 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
94 * inside the path - always follow.
95 * in the last component in creation/removal/renaming - never follow.
96 * if LOOKUP_FOLLOW passed - follow.
97 * if the pathname has trailing slashes - follow.
98 * otherwise - don't follow.
99 * (applied in that order).
101 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
102 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
103 * During the 2.4 we need to fix the userland stuff depending on it -
104 * hopefully we will be able to get rid of that wart in 2.5. So far only
105 * XEmacs seems to be relying on it...
108 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
109 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
110 * any extra contention...
113 /* In order to reduce some races, while at the same time doing additional
114 * checking and hopefully speeding things up, we copy filenames to the
115 * kernel data space before using them..
117 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
118 * PATH_MAX includes the nul terminator --RR.
120 static char *getname_flags(const char __user
*filename
, int flags
, int *empty
)
122 char *result
= __getname(), *err
;
125 if (unlikely(!result
))
126 return ERR_PTR(-ENOMEM
);
128 len
= strncpy_from_user(result
, filename
, PATH_MAX
);
130 if (unlikely(len
< 0))
133 /* The empty path is special. */
134 if (unlikely(!len
)) {
137 err
= ERR_PTR(-ENOENT
);
138 if (!(flags
& LOOKUP_EMPTY
))
142 err
= ERR_PTR(-ENAMETOOLONG
);
143 if (likely(len
< PATH_MAX
)) {
144 audit_getname(result
);
153 char *getname(const char __user
* filename
)
155 return getname_flags(filename
, 0, NULL
);
158 #ifdef CONFIG_AUDITSYSCALL
159 void putname(const char *name
)
161 if (unlikely(!audit_dummy_context()))
166 EXPORT_SYMBOL(putname
);
169 static int check_acl(struct inode
*inode
, int mask
)
171 #ifdef CONFIG_FS_POSIX_ACL
172 struct posix_acl
*acl
;
174 if (mask
& MAY_NOT_BLOCK
) {
175 acl
= get_cached_acl_rcu(inode
, ACL_TYPE_ACCESS
);
178 /* no ->get_acl() calls in RCU mode... */
179 if (acl
== ACL_NOT_CACHED
)
181 return posix_acl_permission(inode
, acl
, mask
& ~MAY_NOT_BLOCK
);
184 acl
= get_cached_acl(inode
, ACL_TYPE_ACCESS
);
187 * A filesystem can force a ACL callback by just never filling the
188 * ACL cache. But normally you'd fill the cache either at inode
189 * instantiation time, or on the first ->get_acl call.
191 * If the filesystem doesn't have a get_acl() function at all, we'll
192 * just create the negative cache entry.
194 if (acl
== ACL_NOT_CACHED
) {
195 if (inode
->i_op
->get_acl
) {
196 acl
= inode
->i_op
->get_acl(inode
, ACL_TYPE_ACCESS
);
200 set_cached_acl(inode
, ACL_TYPE_ACCESS
, NULL
);
206 int error
= posix_acl_permission(inode
, acl
, mask
);
207 posix_acl_release(acl
);
216 * This does the basic permission checking
218 static int acl_permission_check(struct inode
*inode
, int mask
)
220 unsigned int mode
= inode
->i_mode
;
222 if (likely(uid_eq(current_fsuid(), inode
->i_uid
)))
225 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
)) {
226 int error
= check_acl(inode
, mask
);
227 if (error
!= -EAGAIN
)
231 if (in_group_p(inode
->i_gid
))
236 * If the DACs are ok we don't need any capability check.
238 if ((mask
& ~mode
& (MAY_READ
| MAY_WRITE
| MAY_EXEC
)) == 0)
244 * generic_permission - check for access rights on a Posix-like filesystem
245 * @inode: inode to check access rights for
246 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
248 * Used to check for read/write/execute permissions on a file.
249 * We use "fsuid" for this, letting us set arbitrary permissions
250 * for filesystem access without changing the "normal" uids which
251 * are used for other things.
253 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
254 * request cannot be satisfied (eg. requires blocking or too much complexity).
255 * It would then be called again in ref-walk mode.
257 int generic_permission(struct inode
*inode
, int mask
)
262 * Do the basic permission checks.
264 ret
= acl_permission_check(inode
, mask
);
268 if (S_ISDIR(inode
->i_mode
)) {
269 /* DACs are overridable for directories */
270 if (inode_capable(inode
, CAP_DAC_OVERRIDE
))
272 if (!(mask
& MAY_WRITE
))
273 if (inode_capable(inode
, CAP_DAC_READ_SEARCH
))
278 * Read/write DACs are always overridable.
279 * Executable DACs are overridable when there is
280 * at least one exec bit set.
282 if (!(mask
& MAY_EXEC
) || (inode
->i_mode
& S_IXUGO
))
283 if (inode_capable(inode
, CAP_DAC_OVERRIDE
))
287 * Searching includes executable on directories, else just read.
289 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
290 if (mask
== MAY_READ
)
291 if (inode_capable(inode
, CAP_DAC_READ_SEARCH
))
298 * We _really_ want to just do "generic_permission()" without
299 * even looking at the inode->i_op values. So we keep a cache
300 * flag in inode->i_opflags, that says "this has not special
301 * permission function, use the fast case".
303 static inline int do_inode_permission(struct inode
*inode
, int mask
)
305 if (unlikely(!(inode
->i_opflags
& IOP_FASTPERM
))) {
306 if (likely(inode
->i_op
->permission
))
307 return inode
->i_op
->permission(inode
, mask
);
309 /* This gets set once for the inode lifetime */
310 spin_lock(&inode
->i_lock
);
311 inode
->i_opflags
|= IOP_FASTPERM
;
312 spin_unlock(&inode
->i_lock
);
314 return generic_permission(inode
, mask
);
318 * inode_permission - check for access rights to a given inode
319 * @inode: inode to check permission on
320 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
322 * Used to check for read/write/execute permissions on an inode.
323 * We use "fsuid" for this, letting us set arbitrary permissions
324 * for filesystem access without changing the "normal" uids which
325 * are used for other things.
327 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
329 int inode_permission(struct inode
*inode
, int mask
)
333 if (unlikely(mask
& MAY_WRITE
)) {
334 umode_t mode
= inode
->i_mode
;
337 * Nobody gets write access to a read-only fs.
339 if (IS_RDONLY(inode
) &&
340 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
344 * Nobody gets write access to an immutable file.
346 if (IS_IMMUTABLE(inode
))
350 retval
= do_inode_permission(inode
, mask
);
354 retval
= devcgroup_inode_permission(inode
, mask
);
358 return security_inode_permission(inode
, mask
);
362 * path_get - get a reference to a path
363 * @path: path to get the reference to
365 * Given a path increment the reference count to the dentry and the vfsmount.
367 void path_get(struct path
*path
)
372 EXPORT_SYMBOL(path_get
);
375 * path_put - put a reference to a path
376 * @path: path to put the reference to
378 * Given a path decrement the reference count to the dentry and the vfsmount.
380 void path_put(struct path
*path
)
385 EXPORT_SYMBOL(path_put
);
388 * Path walking has 2 modes, rcu-walk and ref-walk (see
389 * Documentation/filesystems/path-lookup.txt). In situations when we can't
390 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
391 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
392 * mode. Refcounts are grabbed at the last known good point before rcu-walk
393 * got stuck, so ref-walk may continue from there. If this is not successful
394 * (eg. a seqcount has changed), then failure is returned and it's up to caller
395 * to restart the path walk from the beginning in ref-walk mode.
399 * unlazy_walk - try to switch to ref-walk mode.
400 * @nd: nameidata pathwalk data
401 * @dentry: child of nd->path.dentry or NULL
402 * Returns: 0 on success, -ECHILD on failure
404 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
405 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
406 * @nd or NULL. Must be called from rcu-walk context.
408 static int unlazy_walk(struct nameidata
*nd
, struct dentry
*dentry
)
410 struct fs_struct
*fs
= current
->fs
;
411 struct dentry
*parent
= nd
->path
.dentry
;
414 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
415 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
417 spin_lock(&fs
->lock
);
418 if (nd
->root
.mnt
!= fs
->root
.mnt
||
419 nd
->root
.dentry
!= fs
->root
.dentry
)
422 spin_lock(&parent
->d_lock
);
424 if (!__d_rcu_to_refcount(parent
, nd
->seq
))
426 BUG_ON(nd
->inode
!= parent
->d_inode
);
428 if (dentry
->d_parent
!= parent
)
430 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
431 if (!__d_rcu_to_refcount(dentry
, nd
->seq
))
434 * If the sequence check on the child dentry passed, then
435 * the child has not been removed from its parent. This
436 * means the parent dentry must be valid and able to take
437 * a reference at this point.
439 BUG_ON(!IS_ROOT(dentry
) && dentry
->d_parent
!= parent
);
440 BUG_ON(!parent
->d_count
);
442 spin_unlock(&dentry
->d_lock
);
444 spin_unlock(&parent
->d_lock
);
447 spin_unlock(&fs
->lock
);
449 mntget(nd
->path
.mnt
);
452 br_read_unlock(&vfsmount_lock
);
453 nd
->flags
&= ~LOOKUP_RCU
;
457 spin_unlock(&dentry
->d_lock
);
459 spin_unlock(&parent
->d_lock
);
462 spin_unlock(&fs
->lock
);
466 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
468 return dentry
->d_op
->d_revalidate(dentry
, flags
);
472 * complete_walk - successful completion of path walk
473 * @nd: pointer nameidata
475 * If we had been in RCU mode, drop out of it and legitimize nd->path.
476 * Revalidate the final result, unless we'd already done that during
477 * the path walk or the filesystem doesn't ask for it. Return 0 on
478 * success, -error on failure. In case of failure caller does not
479 * need to drop nd->path.
481 static int complete_walk(struct nameidata
*nd
)
483 struct dentry
*dentry
= nd
->path
.dentry
;
486 if (nd
->flags
& LOOKUP_RCU
) {
487 nd
->flags
&= ~LOOKUP_RCU
;
488 if (!(nd
->flags
& LOOKUP_ROOT
))
490 spin_lock(&dentry
->d_lock
);
491 if (unlikely(!__d_rcu_to_refcount(dentry
, nd
->seq
))) {
492 spin_unlock(&dentry
->d_lock
);
494 br_read_unlock(&vfsmount_lock
);
497 BUG_ON(nd
->inode
!= dentry
->d_inode
);
498 spin_unlock(&dentry
->d_lock
);
499 mntget(nd
->path
.mnt
);
501 br_read_unlock(&vfsmount_lock
);
504 if (likely(!(nd
->flags
& LOOKUP_JUMPED
)))
507 if (likely(!(dentry
->d_flags
& DCACHE_OP_REVALIDATE
)))
510 if (likely(!(dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
)))
513 /* Note: we do not d_invalidate() */
514 status
= d_revalidate(dentry
, nd
->flags
);
525 static __always_inline
void set_root(struct nameidata
*nd
)
528 get_fs_root(current
->fs
, &nd
->root
);
531 static int link_path_walk(const char *, struct nameidata
*);
533 static __always_inline
void set_root_rcu(struct nameidata
*nd
)
536 struct fs_struct
*fs
= current
->fs
;
540 seq
= read_seqcount_begin(&fs
->seq
);
542 nd
->seq
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
543 } while (read_seqcount_retry(&fs
->seq
, seq
));
547 static __always_inline
int __vfs_follow_link(struct nameidata
*nd
, const char *link
)
559 nd
->flags
|= LOOKUP_JUMPED
;
561 nd
->inode
= nd
->path
.dentry
->d_inode
;
563 ret
= link_path_walk(link
, nd
);
567 return PTR_ERR(link
);
570 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
573 if (path
->mnt
!= nd
->path
.mnt
)
577 static inline void path_to_nameidata(const struct path
*path
,
578 struct nameidata
*nd
)
580 if (!(nd
->flags
& LOOKUP_RCU
)) {
581 dput(nd
->path
.dentry
);
582 if (nd
->path
.mnt
!= path
->mnt
)
583 mntput(nd
->path
.mnt
);
585 nd
->path
.mnt
= path
->mnt
;
586 nd
->path
.dentry
= path
->dentry
;
589 static inline void put_link(struct nameidata
*nd
, struct path
*link
, void *cookie
)
591 struct inode
*inode
= link
->dentry
->d_inode
;
592 if (inode
->i_op
->put_link
)
593 inode
->i_op
->put_link(link
->dentry
, nd
, cookie
);
597 static __always_inline
int
598 follow_link(struct path
*link
, struct nameidata
*nd
, void **p
)
600 struct dentry
*dentry
= link
->dentry
;
604 BUG_ON(nd
->flags
& LOOKUP_RCU
);
606 if (link
->mnt
== nd
->path
.mnt
)
610 if (unlikely(current
->total_link_count
>= 40))
611 goto out_put_nd_path
;
614 current
->total_link_count
++;
617 nd_set_link(nd
, NULL
);
619 error
= security_inode_follow_link(link
->dentry
, nd
);
621 goto out_put_nd_path
;
623 nd
->last_type
= LAST_BIND
;
624 *p
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
632 error
= __vfs_follow_link(nd
, s
);
633 } else if (nd
->last_type
== LAST_BIND
) {
634 nd
->flags
|= LOOKUP_JUMPED
;
635 nd
->inode
= nd
->path
.dentry
->d_inode
;
636 if (nd
->inode
->i_op
->follow_link
) {
637 /* stepped on a _really_ weird one */
643 put_link(nd
, link
, *p
);
654 static int follow_up_rcu(struct path
*path
)
656 struct mount
*mnt
= real_mount(path
->mnt
);
657 struct mount
*parent
;
658 struct dentry
*mountpoint
;
660 parent
= mnt
->mnt_parent
;
661 if (&parent
->mnt
== path
->mnt
)
663 mountpoint
= mnt
->mnt_mountpoint
;
664 path
->dentry
= mountpoint
;
665 path
->mnt
= &parent
->mnt
;
669 int follow_up(struct path
*path
)
671 struct mount
*mnt
= real_mount(path
->mnt
);
672 struct mount
*parent
;
673 struct dentry
*mountpoint
;
675 br_read_lock(&vfsmount_lock
);
676 parent
= mnt
->mnt_parent
;
677 if (&parent
->mnt
== path
->mnt
) {
678 br_read_unlock(&vfsmount_lock
);
681 mntget(&parent
->mnt
);
682 mountpoint
= dget(mnt
->mnt_mountpoint
);
683 br_read_unlock(&vfsmount_lock
);
685 path
->dentry
= mountpoint
;
687 path
->mnt
= &parent
->mnt
;
692 * Perform an automount
693 * - return -EISDIR to tell follow_managed() to stop and return the path we
696 static int follow_automount(struct path
*path
, unsigned flags
,
699 struct vfsmount
*mnt
;
702 if (!path
->dentry
->d_op
|| !path
->dentry
->d_op
->d_automount
)
705 /* We don't want to mount if someone's just doing a stat -
706 * unless they're stat'ing a directory and appended a '/' to
709 * We do, however, want to mount if someone wants to open or
710 * create a file of any type under the mountpoint, wants to
711 * traverse through the mountpoint or wants to open the
712 * mounted directory. Also, autofs may mark negative dentries
713 * as being automount points. These will need the attentions
714 * of the daemon to instantiate them before they can be used.
716 if (!(flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
717 LOOKUP_OPEN
| LOOKUP_CREATE
| LOOKUP_AUTOMOUNT
)) &&
718 path
->dentry
->d_inode
)
721 current
->total_link_count
++;
722 if (current
->total_link_count
>= 40)
725 mnt
= path
->dentry
->d_op
->d_automount(path
);
728 * The filesystem is allowed to return -EISDIR here to indicate
729 * it doesn't want to automount. For instance, autofs would do
730 * this so that its userspace daemon can mount on this dentry.
732 * However, we can only permit this if it's a terminal point in
733 * the path being looked up; if it wasn't then the remainder of
734 * the path is inaccessible and we should say so.
736 if (PTR_ERR(mnt
) == -EISDIR
&& (flags
& LOOKUP_PARENT
))
741 if (!mnt
) /* mount collision */
745 /* lock_mount() may release path->mnt on error */
749 err
= finish_automount(mnt
, path
);
753 /* Someone else made a mount here whilst we were busy */
758 path
->dentry
= dget(mnt
->mnt_root
);
767 * Handle a dentry that is managed in some way.
768 * - Flagged for transit management (autofs)
769 * - Flagged as mountpoint
770 * - Flagged as automount point
772 * This may only be called in refwalk mode.
774 * Serialization is taken care of in namespace.c
776 static int follow_managed(struct path
*path
, unsigned flags
)
778 struct vfsmount
*mnt
= path
->mnt
; /* held by caller, must be left alone */
780 bool need_mntput
= false;
783 /* Given that we're not holding a lock here, we retain the value in a
784 * local variable for each dentry as we look at it so that we don't see
785 * the components of that value change under us */
786 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
787 managed
&= DCACHE_MANAGED_DENTRY
,
788 unlikely(managed
!= 0)) {
789 /* Allow the filesystem to manage the transit without i_mutex
791 if (managed
& DCACHE_MANAGE_TRANSIT
) {
792 BUG_ON(!path
->dentry
->d_op
);
793 BUG_ON(!path
->dentry
->d_op
->d_manage
);
794 ret
= path
->dentry
->d_op
->d_manage(path
->dentry
, false);
799 /* Transit to a mounted filesystem. */
800 if (managed
& DCACHE_MOUNTED
) {
801 struct vfsmount
*mounted
= lookup_mnt(path
);
807 path
->dentry
= dget(mounted
->mnt_root
);
812 /* Something is mounted on this dentry in another
813 * namespace and/or whatever was mounted there in this
814 * namespace got unmounted before we managed to get the
818 /* Handle an automount point */
819 if (managed
& DCACHE_NEED_AUTOMOUNT
) {
820 ret
= follow_automount(path
, flags
, &need_mntput
);
826 /* We didn't change the current path point */
830 if (need_mntput
&& path
->mnt
== mnt
)
834 return ret
< 0 ? ret
: need_mntput
;
837 int follow_down_one(struct path
*path
)
839 struct vfsmount
*mounted
;
841 mounted
= lookup_mnt(path
);
846 path
->dentry
= dget(mounted
->mnt_root
);
852 static inline bool managed_dentry_might_block(struct dentry
*dentry
)
854 return (dentry
->d_flags
& DCACHE_MANAGE_TRANSIT
&&
855 dentry
->d_op
->d_manage(dentry
, true) < 0);
859 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
860 * we meet a managed dentry that would need blocking.
862 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
,
863 struct inode
**inode
)
866 struct mount
*mounted
;
868 * Don't forget we might have a non-mountpoint managed dentry
869 * that wants to block transit.
871 if (unlikely(managed_dentry_might_block(path
->dentry
)))
874 if (!d_mountpoint(path
->dentry
))
877 mounted
= __lookup_mnt(path
->mnt
, path
->dentry
, 1);
880 path
->mnt
= &mounted
->mnt
;
881 path
->dentry
= mounted
->mnt
.mnt_root
;
882 nd
->flags
|= LOOKUP_JUMPED
;
883 nd
->seq
= read_seqcount_begin(&path
->dentry
->d_seq
);
885 * Update the inode too. We don't need to re-check the
886 * dentry sequence number here after this d_inode read,
887 * because a mount-point is always pinned.
889 *inode
= path
->dentry
->d_inode
;
894 static void follow_mount_rcu(struct nameidata
*nd
)
896 while (d_mountpoint(nd
->path
.dentry
)) {
897 struct mount
*mounted
;
898 mounted
= __lookup_mnt(nd
->path
.mnt
, nd
->path
.dentry
, 1);
901 nd
->path
.mnt
= &mounted
->mnt
;
902 nd
->path
.dentry
= mounted
->mnt
.mnt_root
;
903 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
907 static int follow_dotdot_rcu(struct nameidata
*nd
)
912 if (nd
->path
.dentry
== nd
->root
.dentry
&&
913 nd
->path
.mnt
== nd
->root
.mnt
) {
916 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
917 struct dentry
*old
= nd
->path
.dentry
;
918 struct dentry
*parent
= old
->d_parent
;
921 seq
= read_seqcount_begin(&parent
->d_seq
);
922 if (read_seqcount_retry(&old
->d_seq
, nd
->seq
))
924 nd
->path
.dentry
= parent
;
928 if (!follow_up_rcu(&nd
->path
))
930 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
932 follow_mount_rcu(nd
);
933 nd
->inode
= nd
->path
.dentry
->d_inode
;
937 nd
->flags
&= ~LOOKUP_RCU
;
938 if (!(nd
->flags
& LOOKUP_ROOT
))
941 br_read_unlock(&vfsmount_lock
);
946 * Follow down to the covering mount currently visible to userspace. At each
947 * point, the filesystem owning that dentry may be queried as to whether the
948 * caller is permitted to proceed or not.
950 int follow_down(struct path
*path
)
955 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
956 unlikely(managed
& DCACHE_MANAGED_DENTRY
)) {
957 /* Allow the filesystem to manage the transit without i_mutex
960 * We indicate to the filesystem if someone is trying to mount
961 * something here. This gives autofs the chance to deny anyone
962 * other than its daemon the right to mount on its
965 * The filesystem may sleep at this point.
967 if (managed
& DCACHE_MANAGE_TRANSIT
) {
968 BUG_ON(!path
->dentry
->d_op
);
969 BUG_ON(!path
->dentry
->d_op
->d_manage
);
970 ret
= path
->dentry
->d_op
->d_manage(
971 path
->dentry
, false);
973 return ret
== -EISDIR
? 0 : ret
;
976 /* Transit to a mounted filesystem. */
977 if (managed
& DCACHE_MOUNTED
) {
978 struct vfsmount
*mounted
= lookup_mnt(path
);
984 path
->dentry
= dget(mounted
->mnt_root
);
988 /* Don't handle automount points here */
995 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
997 static void follow_mount(struct path
*path
)
999 while (d_mountpoint(path
->dentry
)) {
1000 struct vfsmount
*mounted
= lookup_mnt(path
);
1005 path
->mnt
= mounted
;
1006 path
->dentry
= dget(mounted
->mnt_root
);
1010 static void follow_dotdot(struct nameidata
*nd
)
1015 struct dentry
*old
= nd
->path
.dentry
;
1017 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1018 nd
->path
.mnt
== nd
->root
.mnt
) {
1021 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1022 /* rare case of legitimate dget_parent()... */
1023 nd
->path
.dentry
= dget_parent(nd
->path
.dentry
);
1027 if (!follow_up(&nd
->path
))
1030 follow_mount(&nd
->path
);
1031 nd
->inode
= nd
->path
.dentry
->d_inode
;
1035 * This looks up the name in dcache, possibly revalidates the old dentry and
1036 * allocates a new one if not found or not valid. In the need_lookup argument
1037 * returns whether i_op->lookup is necessary.
1039 * dir->d_inode->i_mutex must be held
1041 static struct dentry
*lookup_dcache(struct qstr
*name
, struct dentry
*dir
,
1042 unsigned int flags
, bool *need_lookup
)
1044 struct dentry
*dentry
;
1047 *need_lookup
= false;
1048 dentry
= d_lookup(dir
, name
);
1050 if (d_need_lookup(dentry
)) {
1051 *need_lookup
= true;
1052 } else if (dentry
->d_flags
& DCACHE_OP_REVALIDATE
) {
1053 error
= d_revalidate(dentry
, flags
);
1054 if (unlikely(error
<= 0)) {
1057 return ERR_PTR(error
);
1058 } else if (!d_invalidate(dentry
)) {
1067 dentry
= d_alloc(dir
, name
);
1068 if (unlikely(!dentry
))
1069 return ERR_PTR(-ENOMEM
);
1071 *need_lookup
= true;
1077 * Call i_op->lookup on the dentry. The dentry must be negative but may be
1078 * hashed if it was pouplated with DCACHE_NEED_LOOKUP.
1080 * dir->d_inode->i_mutex must be held
1082 static struct dentry
*lookup_real(struct inode
*dir
, struct dentry
*dentry
,
1087 /* Don't create child dentry for a dead directory. */
1088 if (unlikely(IS_DEADDIR(dir
))) {
1090 return ERR_PTR(-ENOENT
);
1093 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1094 if (unlikely(old
)) {
1101 static struct dentry
*__lookup_hash(struct qstr
*name
,
1102 struct dentry
*base
, unsigned int flags
)
1105 struct dentry
*dentry
;
1107 dentry
= lookup_dcache(name
, base
, flags
, &need_lookup
);
1111 return lookup_real(base
->d_inode
, dentry
, flags
);
1115 * It's more convoluted than I'd like it to be, but... it's still fairly
1116 * small and for now I'd prefer to have fast path as straight as possible.
1117 * It _is_ time-critical.
1119 static int lookup_fast(struct nameidata
*nd
, struct qstr
*name
,
1120 struct path
*path
, struct inode
**inode
)
1122 struct vfsmount
*mnt
= nd
->path
.mnt
;
1123 struct dentry
*dentry
, *parent
= nd
->path
.dentry
;
1129 * Rename seqlock is not required here because in the off chance
1130 * of a false negative due to a concurrent rename, we're going to
1131 * do the non-racy lookup, below.
1133 if (nd
->flags
& LOOKUP_RCU
) {
1135 dentry
= __d_lookup_rcu(parent
, name
, &seq
, nd
->inode
);
1140 * This sequence count validates that the inode matches
1141 * the dentry name information from lookup.
1143 *inode
= dentry
->d_inode
;
1144 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
1148 * This sequence count validates that the parent had no
1149 * changes while we did the lookup of the dentry above.
1151 * The memory barrier in read_seqcount_begin of child is
1152 * enough, we can use __read_seqcount_retry here.
1154 if (__read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
1158 if (unlikely(d_need_lookup(dentry
)))
1160 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
)) {
1161 status
= d_revalidate(dentry
, nd
->flags
);
1162 if (unlikely(status
<= 0)) {
1163 if (status
!= -ECHILD
)
1169 path
->dentry
= dentry
;
1170 if (unlikely(!__follow_mount_rcu(nd
, path
, inode
)))
1172 if (unlikely(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
))
1176 if (unlazy_walk(nd
, dentry
))
1179 dentry
= __d_lookup(parent
, name
);
1182 if (unlikely(!dentry
))
1185 if (unlikely(d_need_lookup(dentry
))) {
1190 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
) && need_reval
)
1191 status
= d_revalidate(dentry
, nd
->flags
);
1192 if (unlikely(status
<= 0)) {
1197 if (!d_invalidate(dentry
)) {
1204 path
->dentry
= dentry
;
1205 err
= follow_managed(path
, nd
->flags
);
1206 if (unlikely(err
< 0)) {
1207 path_put_conditional(path
, nd
);
1211 nd
->flags
|= LOOKUP_JUMPED
;
1212 *inode
= path
->dentry
->d_inode
;
1219 /* Fast lookup failed, do it the slow way */
1220 static int lookup_slow(struct nameidata
*nd
, struct qstr
*name
,
1223 struct dentry
*dentry
, *parent
;
1226 parent
= nd
->path
.dentry
;
1227 BUG_ON(nd
->inode
!= parent
->d_inode
);
1229 mutex_lock(&parent
->d_inode
->i_mutex
);
1230 dentry
= __lookup_hash(name
, parent
, nd
->flags
);
1231 mutex_unlock(&parent
->d_inode
->i_mutex
);
1233 return PTR_ERR(dentry
);
1234 path
->mnt
= nd
->path
.mnt
;
1235 path
->dentry
= dentry
;
1236 err
= follow_managed(path
, nd
->flags
);
1237 if (unlikely(err
< 0)) {
1238 path_put_conditional(path
, nd
);
1242 nd
->flags
|= LOOKUP_JUMPED
;
1246 static inline int may_lookup(struct nameidata
*nd
)
1248 if (nd
->flags
& LOOKUP_RCU
) {
1249 int err
= inode_permission(nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1252 if (unlazy_walk(nd
, NULL
))
1255 return inode_permission(nd
->inode
, MAY_EXEC
);
1258 static inline int handle_dots(struct nameidata
*nd
, int type
)
1260 if (type
== LAST_DOTDOT
) {
1261 if (nd
->flags
& LOOKUP_RCU
) {
1262 if (follow_dotdot_rcu(nd
))
1270 static void terminate_walk(struct nameidata
*nd
)
1272 if (!(nd
->flags
& LOOKUP_RCU
)) {
1273 path_put(&nd
->path
);
1275 nd
->flags
&= ~LOOKUP_RCU
;
1276 if (!(nd
->flags
& LOOKUP_ROOT
))
1277 nd
->root
.mnt
= NULL
;
1279 br_read_unlock(&vfsmount_lock
);
1284 * Do we need to follow links? We _really_ want to be able
1285 * to do this check without having to look at inode->i_op,
1286 * so we keep a cache of "no, this doesn't need follow_link"
1287 * for the common case.
1289 static inline int should_follow_link(struct inode
*inode
, int follow
)
1291 if (unlikely(!(inode
->i_opflags
& IOP_NOFOLLOW
))) {
1292 if (likely(inode
->i_op
->follow_link
))
1295 /* This gets set once for the inode lifetime */
1296 spin_lock(&inode
->i_lock
);
1297 inode
->i_opflags
|= IOP_NOFOLLOW
;
1298 spin_unlock(&inode
->i_lock
);
1303 static inline int walk_component(struct nameidata
*nd
, struct path
*path
,
1304 struct qstr
*name
, int type
, int follow
)
1306 struct inode
*inode
;
1309 * "." and ".." are special - ".." especially so because it has
1310 * to be able to know about the current root directory and
1311 * parent relationships.
1313 if (unlikely(type
!= LAST_NORM
))
1314 return handle_dots(nd
, type
);
1315 err
= lookup_fast(nd
, name
, path
, &inode
);
1316 if (unlikely(err
)) {
1320 err
= lookup_slow(nd
, name
, path
);
1324 inode
= path
->dentry
->d_inode
;
1330 if (should_follow_link(inode
, follow
)) {
1331 if (nd
->flags
& LOOKUP_RCU
) {
1332 if (unlikely(unlazy_walk(nd
, path
->dentry
))) {
1337 BUG_ON(inode
!= path
->dentry
->d_inode
);
1340 path_to_nameidata(path
, nd
);
1345 path_to_nameidata(path
, nd
);
1352 * This limits recursive symlink follows to 8, while
1353 * limiting consecutive symlinks to 40.
1355 * Without that kind of total limit, nasty chains of consecutive
1356 * symlinks can cause almost arbitrarily long lookups.
1358 static inline int nested_symlink(struct path
*path
, struct nameidata
*nd
)
1362 if (unlikely(current
->link_count
>= MAX_NESTED_LINKS
)) {
1363 path_put_conditional(path
, nd
);
1364 path_put(&nd
->path
);
1367 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
1370 current
->link_count
++;
1373 struct path link
= *path
;
1376 res
= follow_link(&link
, nd
, &cookie
);
1379 res
= walk_component(nd
, path
, &nd
->last
,
1380 nd
->last_type
, LOOKUP_FOLLOW
);
1381 put_link(nd
, &link
, cookie
);
1384 current
->link_count
--;
1390 * We really don't want to look at inode->i_op->lookup
1391 * when we don't have to. So we keep a cache bit in
1392 * the inode ->i_opflags field that says "yes, we can
1393 * do lookup on this inode".
1395 static inline int can_lookup(struct inode
*inode
)
1397 if (likely(inode
->i_opflags
& IOP_LOOKUP
))
1399 if (likely(!inode
->i_op
->lookup
))
1402 /* We do this once for the lifetime of the inode */
1403 spin_lock(&inode
->i_lock
);
1404 inode
->i_opflags
|= IOP_LOOKUP
;
1405 spin_unlock(&inode
->i_lock
);
1410 * We can do the critical dentry name comparison and hashing
1411 * operations one word at a time, but we are limited to:
1413 * - Architectures with fast unaligned word accesses. We could
1414 * do a "get_unaligned()" if this helps and is sufficiently
1417 * - Little-endian machines (so that we can generate the mask
1418 * of low bytes efficiently). Again, we *could* do a byte
1419 * swapping load on big-endian architectures if that is not
1420 * expensive enough to make the optimization worthless.
1422 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1423 * do not trap on the (extremely unlikely) case of a page
1424 * crossing operation.
1426 * - Furthermore, we need an efficient 64-bit compile for the
1427 * 64-bit case in order to generate the "number of bytes in
1428 * the final mask". Again, that could be replaced with a
1429 * efficient population count instruction or similar.
1431 #ifdef CONFIG_DCACHE_WORD_ACCESS
1433 #include <asm/word-at-a-time.h>
1437 static inline unsigned int fold_hash(unsigned long hash
)
1439 hash
+= hash
>> (8*sizeof(int));
1443 #else /* 32-bit case */
1445 #define fold_hash(x) (x)
1449 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1451 unsigned long a
, mask
;
1452 unsigned long hash
= 0;
1455 a
= load_unaligned_zeropad(name
);
1456 if (len
< sizeof(unsigned long))
1460 name
+= sizeof(unsigned long);
1461 len
-= sizeof(unsigned long);
1465 mask
= ~(~0ul << len
*8);
1468 return fold_hash(hash
);
1470 EXPORT_SYMBOL(full_name_hash
);
1473 * Calculate the length and hash of the path component, and
1474 * return the length of the component;
1476 static inline unsigned long hash_name(const char *name
, unsigned int *hashp
)
1478 unsigned long a
, b
, adata
, bdata
, mask
, hash
, len
;
1479 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
1482 len
= -sizeof(unsigned long);
1484 hash
= (hash
+ a
) * 9;
1485 len
+= sizeof(unsigned long);
1486 a
= load_unaligned_zeropad(name
+len
);
1487 b
= a
^ REPEAT_BYTE('/');
1488 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
1490 adata
= prep_zero_mask(a
, adata
, &constants
);
1491 bdata
= prep_zero_mask(b
, bdata
, &constants
);
1493 mask
= create_zero_mask(adata
| bdata
);
1495 hash
+= a
& zero_bytemask(mask
);
1496 *hashp
= fold_hash(hash
);
1498 return len
+ find_zero(mask
);
1503 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1505 unsigned long hash
= init_name_hash();
1507 hash
= partial_name_hash(*name
++, hash
);
1508 return end_name_hash(hash
);
1510 EXPORT_SYMBOL(full_name_hash
);
1513 * We know there's a real path component here of at least
1516 static inline unsigned long hash_name(const char *name
, unsigned int *hashp
)
1518 unsigned long hash
= init_name_hash();
1519 unsigned long len
= 0, c
;
1521 c
= (unsigned char)*name
;
1524 hash
= partial_name_hash(c
, hash
);
1525 c
= (unsigned char)name
[len
];
1526 } while (c
&& c
!= '/');
1527 *hashp
= end_name_hash(hash
);
1535 * This is the basic name resolution function, turning a pathname into
1536 * the final dentry. We expect 'base' to be positive and a directory.
1538 * Returns 0 and nd will have valid dentry and mnt on success.
1539 * Returns error and drops reference to input namei data on failure.
1541 static int link_path_walk(const char *name
, struct nameidata
*nd
)
1551 /* At this point we know we have a real path component. */
1557 err
= may_lookup(nd
);
1561 len
= hash_name(name
, &this.hash
);
1566 if (name
[0] == '.') switch (len
) {
1568 if (name
[1] == '.') {
1570 nd
->flags
|= LOOKUP_JUMPED
;
1576 if (likely(type
== LAST_NORM
)) {
1577 struct dentry
*parent
= nd
->path
.dentry
;
1578 nd
->flags
&= ~LOOKUP_JUMPED
;
1579 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
1580 err
= parent
->d_op
->d_hash(parent
, nd
->inode
,
1588 goto last_component
;
1590 * If it wasn't NUL, we know it was '/'. Skip that
1591 * slash, and continue until no more slashes.
1595 } while (unlikely(name
[len
] == '/'));
1597 goto last_component
;
1600 err
= walk_component(nd
, &next
, &this, type
, LOOKUP_FOLLOW
);
1605 err
= nested_symlink(&next
, nd
);
1609 if (can_lookup(nd
->inode
))
1613 /* here ends the main loop */
1617 nd
->last_type
= type
;
1624 static int path_init(int dfd
, const char *name
, unsigned int flags
,
1625 struct nameidata
*nd
, struct file
**fp
)
1631 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1632 nd
->flags
= flags
| LOOKUP_JUMPED
;
1634 if (flags
& LOOKUP_ROOT
) {
1635 struct inode
*inode
= nd
->root
.dentry
->d_inode
;
1637 if (!inode
->i_op
->lookup
)
1639 retval
= inode_permission(inode
, MAY_EXEC
);
1643 nd
->path
= nd
->root
;
1645 if (flags
& LOOKUP_RCU
) {
1646 br_read_lock(&vfsmount_lock
);
1648 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1650 path_get(&nd
->path
);
1655 nd
->root
.mnt
= NULL
;
1658 if (flags
& LOOKUP_RCU
) {
1659 br_read_lock(&vfsmount_lock
);
1664 path_get(&nd
->root
);
1666 nd
->path
= nd
->root
;
1667 } else if (dfd
== AT_FDCWD
) {
1668 if (flags
& LOOKUP_RCU
) {
1669 struct fs_struct
*fs
= current
->fs
;
1672 br_read_lock(&vfsmount_lock
);
1676 seq
= read_seqcount_begin(&fs
->seq
);
1678 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1679 } while (read_seqcount_retry(&fs
->seq
, seq
));
1681 get_fs_pwd(current
->fs
, &nd
->path
);
1684 struct dentry
*dentry
;
1686 file
= fget_raw_light(dfd
, &fput_needed
);
1691 dentry
= file
->f_path
.dentry
;
1695 if (!S_ISDIR(dentry
->d_inode
->i_mode
))
1698 retval
= inode_permission(dentry
->d_inode
, MAY_EXEC
);
1703 nd
->path
= file
->f_path
;
1704 if (flags
& LOOKUP_RCU
) {
1707 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1708 br_read_lock(&vfsmount_lock
);
1711 path_get(&file
->f_path
);
1712 fput_light(file
, fput_needed
);
1716 nd
->inode
= nd
->path
.dentry
->d_inode
;
1720 fput_light(file
, fput_needed
);
1725 static inline int lookup_last(struct nameidata
*nd
, struct path
*path
)
1727 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
1728 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
1730 nd
->flags
&= ~LOOKUP_PARENT
;
1731 return walk_component(nd
, path
, &nd
->last
, nd
->last_type
,
1732 nd
->flags
& LOOKUP_FOLLOW
);
1735 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1736 static int path_lookupat(int dfd
, const char *name
,
1737 unsigned int flags
, struct nameidata
*nd
)
1739 struct file
*base
= NULL
;
1744 * Path walking is largely split up into 2 different synchronisation
1745 * schemes, rcu-walk and ref-walk (explained in
1746 * Documentation/filesystems/path-lookup.txt). These share much of the
1747 * path walk code, but some things particularly setup, cleanup, and
1748 * following mounts are sufficiently divergent that functions are
1749 * duplicated. Typically there is a function foo(), and its RCU
1750 * analogue, foo_rcu().
1752 * -ECHILD is the error number of choice (just to avoid clashes) that
1753 * is returned if some aspect of an rcu-walk fails. Such an error must
1754 * be handled by restarting a traditional ref-walk (which will always
1755 * be able to complete).
1757 err
= path_init(dfd
, name
, flags
| LOOKUP_PARENT
, nd
, &base
);
1762 current
->total_link_count
= 0;
1763 err
= link_path_walk(name
, nd
);
1765 if (!err
&& !(flags
& LOOKUP_PARENT
)) {
1766 err
= lookup_last(nd
, &path
);
1769 struct path link
= path
;
1770 nd
->flags
|= LOOKUP_PARENT
;
1771 err
= follow_link(&link
, nd
, &cookie
);
1774 err
= lookup_last(nd
, &path
);
1775 put_link(nd
, &link
, cookie
);
1780 err
= complete_walk(nd
);
1782 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
) {
1783 if (!nd
->inode
->i_op
->lookup
) {
1784 path_put(&nd
->path
);
1792 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
1793 path_put(&nd
->root
);
1794 nd
->root
.mnt
= NULL
;
1799 static int do_path_lookup(int dfd
, const char *name
,
1800 unsigned int flags
, struct nameidata
*nd
)
1802 int retval
= path_lookupat(dfd
, name
, flags
| LOOKUP_RCU
, nd
);
1803 if (unlikely(retval
== -ECHILD
))
1804 retval
= path_lookupat(dfd
, name
, flags
, nd
);
1805 if (unlikely(retval
== -ESTALE
))
1806 retval
= path_lookupat(dfd
, name
, flags
| LOOKUP_REVAL
, nd
);
1808 if (likely(!retval
)) {
1809 if (unlikely(!audit_dummy_context())) {
1810 if (nd
->path
.dentry
&& nd
->inode
)
1811 audit_inode(name
, nd
->path
.dentry
);
1817 int kern_path_parent(const char *name
, struct nameidata
*nd
)
1819 return do_path_lookup(AT_FDCWD
, name
, LOOKUP_PARENT
, nd
);
1822 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
1824 struct nameidata nd
;
1825 int res
= do_path_lookup(AT_FDCWD
, name
, flags
, &nd
);
1832 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1833 * @dentry: pointer to dentry of the base directory
1834 * @mnt: pointer to vfs mount of the base directory
1835 * @name: pointer to file name
1836 * @flags: lookup flags
1837 * @path: pointer to struct path to fill
1839 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
1840 const char *name
, unsigned int flags
,
1843 struct nameidata nd
;
1845 nd
.root
.dentry
= dentry
;
1847 BUG_ON(flags
& LOOKUP_PARENT
);
1848 /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
1849 err
= do_path_lookup(AT_FDCWD
, name
, flags
| LOOKUP_ROOT
, &nd
);
1856 * Restricted form of lookup. Doesn't follow links, single-component only,
1857 * needs parent already locked. Doesn't follow mounts.
1860 static struct dentry
*lookup_hash(struct nameidata
*nd
)
1862 return __lookup_hash(&nd
->last
, nd
->path
.dentry
, nd
->flags
);
1866 * lookup_one_len - filesystem helper to lookup single pathname component
1867 * @name: pathname component to lookup
1868 * @base: base directory to lookup from
1869 * @len: maximum length @len should be interpreted to
1871 * Note that this routine is purely a helper for filesystem usage and should
1872 * not be called by generic code. Also note that by using this function the
1873 * nameidata argument is passed to the filesystem methods and a filesystem
1874 * using this helper needs to be prepared for that.
1876 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
1882 WARN_ON_ONCE(!mutex_is_locked(&base
->d_inode
->i_mutex
));
1886 this.hash
= full_name_hash(name
, len
);
1888 return ERR_PTR(-EACCES
);
1891 c
= *(const unsigned char *)name
++;
1892 if (c
== '/' || c
== '\0')
1893 return ERR_PTR(-EACCES
);
1896 * See if the low-level filesystem might want
1897 * to use its own hash..
1899 if (base
->d_flags
& DCACHE_OP_HASH
) {
1900 int err
= base
->d_op
->d_hash(base
, base
->d_inode
, &this);
1902 return ERR_PTR(err
);
1905 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
1907 return ERR_PTR(err
);
1909 return __lookup_hash(&this, base
, 0);
1912 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
1913 struct path
*path
, int *empty
)
1915 struct nameidata nd
;
1916 char *tmp
= getname_flags(name
, flags
, empty
);
1917 int err
= PTR_ERR(tmp
);
1920 BUG_ON(flags
& LOOKUP_PARENT
);
1922 err
= do_path_lookup(dfd
, tmp
, flags
, &nd
);
1930 int user_path_at(int dfd
, const char __user
*name
, unsigned flags
,
1933 return user_path_at_empty(dfd
, name
, flags
, path
, NULL
);
1936 static int user_path_parent(int dfd
, const char __user
*path
,
1937 struct nameidata
*nd
, char **name
)
1939 char *s
= getname(path
);
1945 error
= do_path_lookup(dfd
, s
, LOOKUP_PARENT
, nd
);
1955 * It's inline, so penalty for filesystems that don't use sticky bit is
1958 static inline int check_sticky(struct inode
*dir
, struct inode
*inode
)
1960 kuid_t fsuid
= current_fsuid();
1962 if (!(dir
->i_mode
& S_ISVTX
))
1964 if (uid_eq(inode
->i_uid
, fsuid
))
1966 if (uid_eq(dir
->i_uid
, fsuid
))
1968 return !inode_capable(inode
, CAP_FOWNER
);
1972 * Check whether we can remove a link victim from directory dir, check
1973 * whether the type of victim is right.
1974 * 1. We can't do it if dir is read-only (done in permission())
1975 * 2. We should have write and exec permissions on dir
1976 * 3. We can't remove anything from append-only dir
1977 * 4. We can't do anything with immutable dir (done in permission())
1978 * 5. If the sticky bit on dir is set we should either
1979 * a. be owner of dir, or
1980 * b. be owner of victim, or
1981 * c. have CAP_FOWNER capability
1982 * 6. If the victim is append-only or immutable we can't do antyhing with
1983 * links pointing to it.
1984 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1985 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1986 * 9. We can't remove a root or mountpoint.
1987 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1988 * nfs_async_unlink().
1990 static int may_delete(struct inode
*dir
,struct dentry
*victim
,int isdir
)
1994 if (!victim
->d_inode
)
1997 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
1998 audit_inode_child(victim
, dir
);
2000 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2005 if (check_sticky(dir
, victim
->d_inode
)||IS_APPEND(victim
->d_inode
)||
2006 IS_IMMUTABLE(victim
->d_inode
) || IS_SWAPFILE(victim
->d_inode
))
2009 if (!S_ISDIR(victim
->d_inode
->i_mode
))
2011 if (IS_ROOT(victim
))
2013 } else if (S_ISDIR(victim
->d_inode
->i_mode
))
2015 if (IS_DEADDIR(dir
))
2017 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2022 /* Check whether we can create an object with dentry child in directory
2024 * 1. We can't do it if child already exists (open has special treatment for
2025 * this case, but since we are inlined it's OK)
2026 * 2. We can't do it if dir is read-only (done in permission())
2027 * 3. We should have write and exec permissions on dir
2028 * 4. We can't do it if dir is immutable (done in permission())
2030 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
2034 if (IS_DEADDIR(dir
))
2036 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2040 * p1 and p2 should be directories on the same fs.
2042 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2047 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2051 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2053 p
= d_ancestor(p2
, p1
);
2055 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2056 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2060 p
= d_ancestor(p1
, p2
);
2062 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2063 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2067 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2068 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2072 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
2074 mutex_unlock(&p1
->d_inode
->i_mutex
);
2076 mutex_unlock(&p2
->d_inode
->i_mutex
);
2077 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2081 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
2082 struct nameidata
*nd
)
2084 int error
= may_create(dir
, dentry
);
2088 if (!dir
->i_op
->create
)
2089 return -EACCES
; /* shouldn't it be ENOSYS? */
2092 error
= security_inode_create(dir
, dentry
, mode
);
2095 error
= dir
->i_op
->create(dir
, dentry
, mode
, !nd
|| (nd
->flags
& LOOKUP_EXCL
));
2097 fsnotify_create(dir
, dentry
);
2101 static int may_open(struct path
*path
, int acc_mode
, int flag
)
2103 struct dentry
*dentry
= path
->dentry
;
2104 struct inode
*inode
= dentry
->d_inode
;
2114 switch (inode
->i_mode
& S_IFMT
) {
2118 if (acc_mode
& MAY_WRITE
)
2123 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
2132 error
= inode_permission(inode
, acc_mode
);
2137 * An append-only file must be opened in append mode for writing.
2139 if (IS_APPEND(inode
)) {
2140 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
2146 /* O_NOATIME can only be set by the owner or superuser */
2147 if (flag
& O_NOATIME
&& !inode_owner_or_capable(inode
))
2153 static int handle_truncate(struct file
*filp
)
2155 struct path
*path
= &filp
->f_path
;
2156 struct inode
*inode
= path
->dentry
->d_inode
;
2157 int error
= get_write_access(inode
);
2161 * Refuse to truncate files with mandatory locks held on them.
2163 error
= locks_verify_locked(inode
);
2165 error
= security_path_truncate(path
);
2167 error
= do_truncate(path
->dentry
, 0,
2168 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
2171 put_write_access(inode
);
2175 static inline int open_to_namei_flags(int flag
)
2177 if ((flag
& O_ACCMODE
) == 3)
2182 static int may_o_create(struct path
*dir
, struct dentry
*dentry
, umode_t mode
)
2184 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
2188 error
= inode_permission(dir
->dentry
->d_inode
, MAY_WRITE
| MAY_EXEC
);
2192 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
2195 static int atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
2196 struct path
*path
, struct file
*file
,
2197 const struct open_flags
*op
,
2198 bool *want_write
, bool need_lookup
,
2201 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
2202 unsigned open_flag
= open_to_namei_flags(op
->open_flag
);
2206 int create_error
= 0;
2207 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
2209 BUG_ON(dentry
->d_inode
);
2211 /* Don't create child dentry for a dead directory. */
2212 if (unlikely(IS_DEADDIR(dir
))) {
2217 mode
= op
->mode
& S_IALLUGO
;
2218 if ((open_flag
& O_CREAT
) && !IS_POSIXACL(dir
))
2219 mode
&= ~current_umask();
2221 if (open_flag
& O_EXCL
) {
2222 open_flag
&= ~O_TRUNC
;
2223 *opened
|= FILE_CREATED
;
2227 * Checking write permission is tricky, bacuse we don't know if we are
2228 * going to actually need it: O_CREAT opens should work as long as the
2229 * file exists. But checking existence breaks atomicity. The trick is
2230 * to check access and if not granted clear O_CREAT from the flags.
2232 * Another problem is returing the "right" error value (e.g. for an
2233 * O_EXCL open we want to return EEXIST not EROFS).
2235 if ((open_flag
& (O_CREAT
| O_TRUNC
)) ||
2236 (open_flag
& O_ACCMODE
) != O_RDONLY
) {
2237 error
= mnt_want_write(nd
->path
.mnt
);
2240 } else if (!(open_flag
& O_CREAT
)) {
2242 * No O_CREATE -> atomicity not a requirement -> fall
2243 * back to lookup + open
2246 } else if (open_flag
& (O_EXCL
| O_TRUNC
)) {
2247 /* Fall back and fail with the right error */
2248 create_error
= error
;
2251 /* No side effects, safe to clear O_CREAT */
2252 create_error
= error
;
2253 open_flag
&= ~O_CREAT
;
2257 if (open_flag
& O_CREAT
) {
2258 error
= may_o_create(&nd
->path
, dentry
, op
->mode
);
2260 create_error
= error
;
2261 if (open_flag
& O_EXCL
)
2263 open_flag
&= ~O_CREAT
;
2267 if (nd
->flags
& LOOKUP_DIRECTORY
)
2268 open_flag
|= O_DIRECTORY
;
2270 file
->f_path
.dentry
= DENTRY_NOT_SET
;
2271 file
->f_path
.mnt
= nd
->path
.mnt
;
2272 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
, open_flag
, mode
,
2275 if (create_error
&& error
== -ENOENT
)
2276 error
= create_error
;
2280 acc_mode
= op
->acc_mode
;
2281 if (*opened
& FILE_CREATED
) {
2282 fsnotify_create(dir
, dentry
);
2283 acc_mode
= MAY_OPEN
;
2286 if (error
) { /* returned 1, that is */
2287 if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
2291 if (file
->f_path
.dentry
) {
2293 dentry
= file
->f_path
.dentry
;
2299 * We didn't have the inode before the open, so check open permission
2302 error
= may_open(&file
->f_path
, acc_mode
, open_flag
);
2312 dentry
= lookup_real(dir
, dentry
, nd
->flags
);
2314 return PTR_ERR(dentry
);
2317 int open_flag
= op
->open_flag
;
2319 error
= create_error
;
2320 if ((open_flag
& O_EXCL
)) {
2321 if (!dentry
->d_inode
)
2323 } else if (!dentry
->d_inode
) {
2325 } else if ((open_flag
& O_TRUNC
) &&
2326 S_ISREG(dentry
->d_inode
->i_mode
)) {
2329 /* will fail later, go on to get the right error */
2333 path
->dentry
= dentry
;
2334 path
->mnt
= nd
->path
.mnt
;
2339 * Lookup, maybe create and open the last component
2341 * Must be called with i_mutex held on parent.
2343 * Returns open file or NULL on success, error otherwise. NULL means no open
2344 * was performed, only lookup.
2346 static int lookup_open(struct nameidata
*nd
, struct path
*path
,
2348 const struct open_flags
*op
,
2349 bool *want_write
, int *opened
)
2351 struct dentry
*dir
= nd
->path
.dentry
;
2352 struct inode
*dir_inode
= dir
->d_inode
;
2353 struct dentry
*dentry
;
2357 *opened
&= ~FILE_CREATED
;
2358 dentry
= lookup_dcache(&nd
->last
, dir
, nd
->flags
, &need_lookup
);
2360 return PTR_ERR(dentry
);
2362 /* Cached positive dentry: will open in f_op->open */
2363 if (!need_lookup
&& dentry
->d_inode
)
2366 if ((nd
->flags
& LOOKUP_OPEN
) && dir_inode
->i_op
->atomic_open
) {
2367 return atomic_open(nd
, dentry
, path
, file
, op
, want_write
,
2368 need_lookup
, opened
);
2372 BUG_ON(dentry
->d_inode
);
2374 dentry
= lookup_real(dir_inode
, dentry
, nd
->flags
);
2376 return PTR_ERR(dentry
);
2379 /* Negative dentry, just create the file */
2380 if (!dentry
->d_inode
&& (op
->open_flag
& O_CREAT
)) {
2381 umode_t mode
= op
->mode
;
2382 if (!IS_POSIXACL(dir
->d_inode
))
2383 mode
&= ~current_umask();
2385 * This write is needed to ensure that a
2386 * rw->ro transition does not occur between
2387 * the time when the file is created and when
2388 * a permanent write count is taken through
2389 * the 'struct file' in finish_open().
2391 error
= mnt_want_write(nd
->path
.mnt
);
2395 *opened
|= FILE_CREATED
;
2396 error
= security_path_mknod(&nd
->path
, dentry
, mode
, 0);
2399 error
= vfs_create(dir
->d_inode
, dentry
, mode
, nd
);
2404 path
->dentry
= dentry
;
2405 path
->mnt
= nd
->path
.mnt
;
2414 * Handle the last step of open()
2416 static int do_last(struct nameidata
*nd
, struct path
*path
,
2417 struct file
*file
, const struct open_flags
*op
,
2418 int *opened
, const char *pathname
)
2420 struct dentry
*dir
= nd
->path
.dentry
;
2421 int open_flag
= op
->open_flag
;
2422 bool will_truncate
= (open_flag
& O_TRUNC
) != 0;
2423 bool want_write
= false;
2424 int acc_mode
= op
->acc_mode
;
2425 struct inode
*inode
;
2426 bool symlink_ok
= false;
2427 struct path save_parent
= { .dentry
= NULL
, .mnt
= NULL
};
2428 bool retried
= false;
2431 nd
->flags
&= ~LOOKUP_PARENT
;
2432 nd
->flags
|= op
->intent
;
2434 switch (nd
->last_type
) {
2437 error
= handle_dots(nd
, nd
->last_type
);
2442 error
= complete_walk(nd
);
2445 audit_inode(pathname
, nd
->path
.dentry
);
2446 if (open_flag
& O_CREAT
) {
2452 error
= complete_walk(nd
);
2455 audit_inode(pathname
, dir
);
2459 if (!(open_flag
& O_CREAT
)) {
2460 if (nd
->last
.name
[nd
->last
.len
])
2461 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2462 if (open_flag
& O_PATH
&& !(nd
->flags
& LOOKUP_FOLLOW
))
2464 /* we _can_ be in RCU mode here */
2465 error
= lookup_fast(nd
, &nd
->last
, path
, &inode
);
2472 BUG_ON(nd
->inode
!= dir
->d_inode
);
2474 /* create side of things */
2476 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
2477 * has been cleared when we got to the last component we are
2480 error
= complete_walk(nd
);
2484 audit_inode(pathname
, dir
);
2486 /* trailing slashes? */
2487 if (nd
->last
.name
[nd
->last
.len
])
2492 mutex_lock(&dir
->d_inode
->i_mutex
);
2493 error
= lookup_open(nd
, path
, file
, op
, &want_write
, opened
);
2494 mutex_unlock(&dir
->d_inode
->i_mutex
);
2500 if ((*opened
& FILE_CREATED
) ||
2501 !S_ISREG(file
->f_path
.dentry
->d_inode
->i_mode
))
2502 will_truncate
= false;
2504 audit_inode(pathname
, file
->f_path
.dentry
);
2508 if (*opened
& FILE_CREATED
) {
2509 /* Don't check for write permission, don't truncate */
2510 open_flag
&= ~O_TRUNC
;
2511 will_truncate
= false;
2512 acc_mode
= MAY_OPEN
;
2513 path_to_nameidata(path
, nd
);
2514 goto finish_open_created
;
2518 * It already exists.
2520 audit_inode(pathname
, path
->dentry
);
2523 * If atomic_open() acquired write access it is dropped now due to
2524 * possible mount and symlink following (this might be optimized away if
2528 mnt_drop_write(nd
->path
.mnt
);
2533 if (open_flag
& O_EXCL
)
2536 error
= follow_managed(path
, nd
->flags
);
2541 nd
->flags
|= LOOKUP_JUMPED
;
2543 BUG_ON(nd
->flags
& LOOKUP_RCU
);
2544 inode
= path
->dentry
->d_inode
;
2546 /* we _can_ be in RCU mode here */
2549 path_to_nameidata(path
, nd
);
2553 if (should_follow_link(inode
, !symlink_ok
)) {
2554 if (nd
->flags
& LOOKUP_RCU
) {
2555 if (unlikely(unlazy_walk(nd
, path
->dentry
))) {
2560 BUG_ON(inode
!= path
->dentry
->d_inode
);
2564 if ((nd
->flags
& LOOKUP_RCU
) || nd
->path
.mnt
!= path
->mnt
) {
2565 path_to_nameidata(path
, nd
);
2567 save_parent
.dentry
= nd
->path
.dentry
;
2568 save_parent
.mnt
= mntget(path
->mnt
);
2569 nd
->path
.dentry
= path
->dentry
;
2573 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
2574 error
= complete_walk(nd
);
2576 path_put(&save_parent
);
2580 if ((open_flag
& O_CREAT
) && S_ISDIR(nd
->inode
->i_mode
))
2583 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !nd
->inode
->i_op
->lookup
)
2585 audit_inode(pathname
, nd
->path
.dentry
);
2587 if (!S_ISREG(nd
->inode
->i_mode
))
2588 will_truncate
= false;
2590 if (will_truncate
) {
2591 error
= mnt_want_write(nd
->path
.mnt
);
2596 finish_open_created
:
2597 error
= may_open(&nd
->path
, acc_mode
, open_flag
);
2600 file
->f_path
.mnt
= nd
->path
.mnt
;
2601 error
= finish_open(file
, nd
->path
.dentry
, NULL
, opened
);
2603 if (error
== -EOPENSTALE
)
2608 error
= open_check_o_direct(file
);
2611 error
= ima_file_check(file
, op
->acc_mode
);
2615 if (will_truncate
) {
2616 error
= handle_truncate(file
);
2622 mnt_drop_write(nd
->path
.mnt
);
2623 path_put(&save_parent
);
2628 path_put_conditional(path
, nd
);
2635 /* If no saved parent or already retried then can't retry */
2636 if (!save_parent
.dentry
|| retried
)
2639 BUG_ON(save_parent
.dentry
!= dir
);
2640 path_put(&nd
->path
);
2641 nd
->path
= save_parent
;
2642 nd
->inode
= dir
->d_inode
;
2643 save_parent
.mnt
= NULL
;
2644 save_parent
.dentry
= NULL
;
2646 mnt_drop_write(nd
->path
.mnt
);
2653 static struct file
*path_openat(int dfd
, const char *pathname
,
2654 struct nameidata
*nd
, const struct open_flags
*op
, int flags
)
2656 struct file
*base
= NULL
;
2662 file
= get_empty_filp();
2664 return ERR_PTR(-ENFILE
);
2666 file
->f_flags
= op
->open_flag
;
2668 error
= path_init(dfd
, pathname
, flags
| LOOKUP_PARENT
, nd
, &base
);
2669 if (unlikely(error
))
2672 current
->total_link_count
= 0;
2673 error
= link_path_walk(pathname
, nd
);
2674 if (unlikely(error
))
2677 error
= do_last(nd
, &path
, file
, op
, &opened
, pathname
);
2678 while (unlikely(error
> 0)) { /* trailing symlink */
2679 struct path link
= path
;
2681 if (!(nd
->flags
& LOOKUP_FOLLOW
)) {
2682 path_put_conditional(&path
, nd
);
2683 path_put(&nd
->path
);
2687 nd
->flags
|= LOOKUP_PARENT
;
2688 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
2689 error
= follow_link(&link
, nd
, &cookie
);
2690 if (unlikely(error
))
2692 error
= do_last(nd
, &path
, file
, op
, &opened
, pathname
);
2693 put_link(nd
, &link
, cookie
);
2696 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
))
2697 path_put(&nd
->root
);
2700 if (!(opened
& FILE_OPENED
)) {
2704 if (unlikely(error
)) {
2705 if (error
== -EOPENSTALE
) {
2706 if (flags
& LOOKUP_RCU
)
2711 file
= ERR_PTR(error
);
2716 struct file
*do_filp_open(int dfd
, const char *pathname
,
2717 const struct open_flags
*op
, int flags
)
2719 struct nameidata nd
;
2722 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
| LOOKUP_RCU
);
2723 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
2724 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
);
2725 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
2726 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
| LOOKUP_REVAL
);
2730 struct file
*do_file_open_root(struct dentry
*dentry
, struct vfsmount
*mnt
,
2731 const char *name
, const struct open_flags
*op
, int flags
)
2733 struct nameidata nd
;
2737 nd
.root
.dentry
= dentry
;
2739 flags
|= LOOKUP_ROOT
;
2741 if (dentry
->d_inode
->i_op
->follow_link
&& op
->intent
& LOOKUP_OPEN
)
2742 return ERR_PTR(-ELOOP
);
2744 file
= path_openat(-1, name
, &nd
, op
, flags
| LOOKUP_RCU
);
2745 if (unlikely(file
== ERR_PTR(-ECHILD
)))
2746 file
= path_openat(-1, name
, &nd
, op
, flags
);
2747 if (unlikely(file
== ERR_PTR(-ESTALE
)))
2748 file
= path_openat(-1, name
, &nd
, op
, flags
| LOOKUP_REVAL
);
2752 struct dentry
*kern_path_create(int dfd
, const char *pathname
, struct path
*path
, int is_dir
)
2754 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
2755 struct nameidata nd
;
2756 int error
= do_path_lookup(dfd
, pathname
, LOOKUP_PARENT
, &nd
);
2758 return ERR_PTR(error
);
2761 * Yucky last component or no last component at all?
2762 * (foo/., foo/.., /////)
2764 if (nd
.last_type
!= LAST_NORM
)
2766 nd
.flags
&= ~LOOKUP_PARENT
;
2767 nd
.flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
2770 * Do the final lookup.
2772 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2773 dentry
= lookup_hash(&nd
);
2777 if (dentry
->d_inode
)
2780 * Special case - lookup gave negative, but... we had foo/bar/
2781 * From the vfs_mknod() POV we just have a negative dentry -
2782 * all is fine. Let's be bastards - you had / on the end, you've
2783 * been asking for (non-existent) directory. -ENOENT for you.
2785 if (unlikely(!is_dir
&& nd
.last
.name
[nd
.last
.len
])) {
2787 dentry
= ERR_PTR(-ENOENT
);
2794 dentry
= ERR_PTR(-EEXIST
);
2796 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2801 EXPORT_SYMBOL(kern_path_create
);
2803 struct dentry
*user_path_create(int dfd
, const char __user
*pathname
, struct path
*path
, int is_dir
)
2805 char *tmp
= getname(pathname
);
2808 return ERR_CAST(tmp
);
2809 res
= kern_path_create(dfd
, tmp
, path
, is_dir
);
2813 EXPORT_SYMBOL(user_path_create
);
2815 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
2817 int error
= may_create(dir
, dentry
);
2822 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
2825 if (!dir
->i_op
->mknod
)
2828 error
= devcgroup_inode_mknod(mode
, dev
);
2832 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
2836 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
2838 fsnotify_create(dir
, dentry
);
2842 static int may_mknod(umode_t mode
)
2844 switch (mode
& S_IFMT
) {
2850 case 0: /* zero mode translates to S_IFREG */
2859 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
2862 struct dentry
*dentry
;
2869 dentry
= user_path_create(dfd
, filename
, &path
, 0);
2871 return PTR_ERR(dentry
);
2873 if (!IS_POSIXACL(path
.dentry
->d_inode
))
2874 mode
&= ~current_umask();
2875 error
= may_mknod(mode
);
2878 error
= mnt_want_write(path
.mnt
);
2881 error
= security_path_mknod(&path
, dentry
, mode
, dev
);
2883 goto out_drop_write
;
2884 switch (mode
& S_IFMT
) {
2885 case 0: case S_IFREG
:
2886 error
= vfs_create(path
.dentry
->d_inode
,dentry
,mode
,NULL
);
2888 case S_IFCHR
: case S_IFBLK
:
2889 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,
2890 new_decode_dev(dev
));
2892 case S_IFIFO
: case S_IFSOCK
:
2893 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,0);
2897 mnt_drop_write(path
.mnt
);
2900 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
2906 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
2908 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
2911 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
2913 int error
= may_create(dir
, dentry
);
2914 unsigned max_links
= dir
->i_sb
->s_max_links
;
2919 if (!dir
->i_op
->mkdir
)
2922 mode
&= (S_IRWXUGO
|S_ISVTX
);
2923 error
= security_inode_mkdir(dir
, dentry
, mode
);
2927 if (max_links
&& dir
->i_nlink
>= max_links
)
2930 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
2932 fsnotify_mkdir(dir
, dentry
);
2936 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, umode_t
, mode
)
2938 struct dentry
*dentry
;
2942 dentry
= user_path_create(dfd
, pathname
, &path
, 1);
2944 return PTR_ERR(dentry
);
2946 if (!IS_POSIXACL(path
.dentry
->d_inode
))
2947 mode
&= ~current_umask();
2948 error
= mnt_want_write(path
.mnt
);
2951 error
= security_path_mkdir(&path
, dentry
, mode
);
2953 goto out_drop_write
;
2954 error
= vfs_mkdir(path
.dentry
->d_inode
, dentry
, mode
);
2956 mnt_drop_write(path
.mnt
);
2959 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
2964 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, umode_t
, mode
)
2966 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
2970 * The dentry_unhash() helper will try to drop the dentry early: we
2971 * should have a usage count of 1 if we're the only user of this
2972 * dentry, and if that is true (possibly after pruning the dcache),
2973 * then we drop the dentry now.
2975 * A low-level filesystem can, if it choses, legally
2978 * if (!d_unhashed(dentry))
2981 * if it cannot handle the case of removing a directory
2982 * that is still in use by something else..
2984 void dentry_unhash(struct dentry
*dentry
)
2986 shrink_dcache_parent(dentry
);
2987 spin_lock(&dentry
->d_lock
);
2988 if (dentry
->d_count
== 1)
2990 spin_unlock(&dentry
->d_lock
);
2993 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2995 int error
= may_delete(dir
, dentry
, 1);
3000 if (!dir
->i_op
->rmdir
)
3004 mutex_lock(&dentry
->d_inode
->i_mutex
);
3007 if (d_mountpoint(dentry
))
3010 error
= security_inode_rmdir(dir
, dentry
);
3014 shrink_dcache_parent(dentry
);
3015 error
= dir
->i_op
->rmdir(dir
, dentry
);
3019 dentry
->d_inode
->i_flags
|= S_DEAD
;
3023 mutex_unlock(&dentry
->d_inode
->i_mutex
);
3030 static long do_rmdir(int dfd
, const char __user
*pathname
)
3034 struct dentry
*dentry
;
3035 struct nameidata nd
;
3037 error
= user_path_parent(dfd
, pathname
, &nd
, &name
);
3041 switch(nd
.last_type
) {
3053 nd
.flags
&= ~LOOKUP_PARENT
;
3055 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3056 dentry
= lookup_hash(&nd
);
3057 error
= PTR_ERR(dentry
);
3060 if (!dentry
->d_inode
) {
3064 error
= mnt_want_write(nd
.path
.mnt
);
3067 error
= security_path_rmdir(&nd
.path
, dentry
);
3070 error
= vfs_rmdir(nd
.path
.dentry
->d_inode
, dentry
);
3072 mnt_drop_write(nd
.path
.mnt
);
3076 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
3083 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
3085 return do_rmdir(AT_FDCWD
, pathname
);
3088 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
)
3090 int error
= may_delete(dir
, dentry
, 0);
3095 if (!dir
->i_op
->unlink
)
3098 mutex_lock(&dentry
->d_inode
->i_mutex
);
3099 if (d_mountpoint(dentry
))
3102 error
= security_inode_unlink(dir
, dentry
);
3104 error
= dir
->i_op
->unlink(dir
, dentry
);
3109 mutex_unlock(&dentry
->d_inode
->i_mutex
);
3111 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
3112 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
3113 fsnotify_link_count(dentry
->d_inode
);
3121 * Make sure that the actual truncation of the file will occur outside its
3122 * directory's i_mutex. Truncate can take a long time if there is a lot of
3123 * writeout happening, and we don't want to prevent access to the directory
3124 * while waiting on the I/O.
3126 static long do_unlinkat(int dfd
, const char __user
*pathname
)
3130 struct dentry
*dentry
;
3131 struct nameidata nd
;
3132 struct inode
*inode
= NULL
;
3134 error
= user_path_parent(dfd
, pathname
, &nd
, &name
);
3139 if (nd
.last_type
!= LAST_NORM
)
3142 nd
.flags
&= ~LOOKUP_PARENT
;
3144 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3145 dentry
= lookup_hash(&nd
);
3146 error
= PTR_ERR(dentry
);
3147 if (!IS_ERR(dentry
)) {
3148 /* Why not before? Because we want correct error value */
3149 if (nd
.last
.name
[nd
.last
.len
])
3151 inode
= dentry
->d_inode
;
3155 error
= mnt_want_write(nd
.path
.mnt
);
3158 error
= security_path_unlink(&nd
.path
, dentry
);
3161 error
= vfs_unlink(nd
.path
.dentry
->d_inode
, dentry
);
3163 mnt_drop_write(nd
.path
.mnt
);
3167 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
3169 iput(inode
); /* truncate the inode here */
3176 error
= !dentry
->d_inode
? -ENOENT
:
3177 S_ISDIR(dentry
->d_inode
->i_mode
) ? -EISDIR
: -ENOTDIR
;
3181 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
3183 if ((flag
& ~AT_REMOVEDIR
) != 0)
3186 if (flag
& AT_REMOVEDIR
)
3187 return do_rmdir(dfd
, pathname
);
3189 return do_unlinkat(dfd
, pathname
);
3192 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
3194 return do_unlinkat(AT_FDCWD
, pathname
);
3197 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
3199 int error
= may_create(dir
, dentry
);
3204 if (!dir
->i_op
->symlink
)
3207 error
= security_inode_symlink(dir
, dentry
, oldname
);
3211 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
3213 fsnotify_create(dir
, dentry
);
3217 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
3218 int, newdfd
, const char __user
*, newname
)
3222 struct dentry
*dentry
;
3225 from
= getname(oldname
);
3227 return PTR_ERR(from
);
3229 dentry
= user_path_create(newdfd
, newname
, &path
, 0);
3230 error
= PTR_ERR(dentry
);
3234 error
= mnt_want_write(path
.mnt
);
3237 error
= security_path_symlink(&path
, dentry
, from
);
3239 goto out_drop_write
;
3240 error
= vfs_symlink(path
.dentry
->d_inode
, dentry
, from
);
3242 mnt_drop_write(path
.mnt
);
3245 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3252 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
3254 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
3257 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
)
3259 struct inode
*inode
= old_dentry
->d_inode
;
3260 unsigned max_links
= dir
->i_sb
->s_max_links
;
3266 error
= may_create(dir
, new_dentry
);
3270 if (dir
->i_sb
!= inode
->i_sb
)
3274 * A link to an append-only or immutable file cannot be created.
3276 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
3278 if (!dir
->i_op
->link
)
3280 if (S_ISDIR(inode
->i_mode
))
3283 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
3287 mutex_lock(&inode
->i_mutex
);
3288 /* Make sure we don't allow creating hardlink to an unlinked file */
3289 if (inode
->i_nlink
== 0)
3291 else if (max_links
&& inode
->i_nlink
>= max_links
)
3294 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
3295 mutex_unlock(&inode
->i_mutex
);
3297 fsnotify_link(dir
, inode
, new_dentry
);
3302 * Hardlinks are often used in delicate situations. We avoid
3303 * security-related surprises by not following symlinks on the
3306 * We don't follow them on the oldname either to be compatible
3307 * with linux 2.0, and to avoid hard-linking to directories
3308 * and other special files. --ADM
3310 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
3311 int, newdfd
, const char __user
*, newname
, int, flags
)
3313 struct dentry
*new_dentry
;
3314 struct path old_path
, new_path
;
3318 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0)
3321 * To use null names we require CAP_DAC_READ_SEARCH
3322 * This ensures that not everyone will be able to create
3323 * handlink using the passed filedescriptor.
3325 if (flags
& AT_EMPTY_PATH
) {
3326 if (!capable(CAP_DAC_READ_SEARCH
))
3331 if (flags
& AT_SYMLINK_FOLLOW
)
3332 how
|= LOOKUP_FOLLOW
;
3334 error
= user_path_at(olddfd
, oldname
, how
, &old_path
);
3338 new_dentry
= user_path_create(newdfd
, newname
, &new_path
, 0);
3339 error
= PTR_ERR(new_dentry
);
3340 if (IS_ERR(new_dentry
))
3344 if (old_path
.mnt
!= new_path
.mnt
)
3346 error
= mnt_want_write(new_path
.mnt
);
3349 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
3351 goto out_drop_write
;
3352 error
= vfs_link(old_path
.dentry
, new_path
.dentry
->d_inode
, new_dentry
);
3354 mnt_drop_write(new_path
.mnt
);
3357 mutex_unlock(&new_path
.dentry
->d_inode
->i_mutex
);
3358 path_put(&new_path
);
3360 path_put(&old_path
);
3365 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
3367 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
3371 * The worst of all namespace operations - renaming directory. "Perverted"
3372 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
3374 * a) we can get into loop creation. Check is done in is_subdir().
3375 * b) race potential - two innocent renames can create a loop together.
3376 * That's where 4.4 screws up. Current fix: serialization on
3377 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
3379 * c) we have to lock _three_ objects - parents and victim (if it exists).
3380 * And that - after we got ->i_mutex on parents (until then we don't know
3381 * whether the target exists). Solution: try to be smart with locking
3382 * order for inodes. We rely on the fact that tree topology may change
3383 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
3384 * move will be locked. Thus we can rank directories by the tree
3385 * (ancestors first) and rank all non-directories after them.
3386 * That works since everybody except rename does "lock parent, lookup,
3387 * lock child" and rename is under ->s_vfs_rename_mutex.
3388 * HOWEVER, it relies on the assumption that any object with ->lookup()
3389 * has no more than 1 dentry. If "hybrid" objects will ever appear,
3390 * we'd better make sure that there's no link(2) for them.
3391 * d) conversion from fhandle to dentry may come in the wrong moment - when
3392 * we are removing the target. Solution: we will have to grab ->i_mutex
3393 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
3394 * ->i_mutex on parents, which works but leads to some truly excessive
3397 static int vfs_rename_dir(struct inode
*old_dir
, struct dentry
*old_dentry
,
3398 struct inode
*new_dir
, struct dentry
*new_dentry
)
3401 struct inode
*target
= new_dentry
->d_inode
;
3402 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
3405 * If we are going to change the parent - check write permissions,
3406 * we'll need to flip '..'.
3408 if (new_dir
!= old_dir
) {
3409 error
= inode_permission(old_dentry
->d_inode
, MAY_WRITE
);
3414 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
3420 mutex_lock(&target
->i_mutex
);
3423 if (d_mountpoint(old_dentry
) || d_mountpoint(new_dentry
))
3427 if (max_links
&& !target
&& new_dir
!= old_dir
&&
3428 new_dir
->i_nlink
>= max_links
)
3432 shrink_dcache_parent(new_dentry
);
3433 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
3438 target
->i_flags
|= S_DEAD
;
3439 dont_mount(new_dentry
);
3443 mutex_unlock(&target
->i_mutex
);
3446 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
3447 d_move(old_dentry
,new_dentry
);
3451 static int vfs_rename_other(struct inode
*old_dir
, struct dentry
*old_dentry
,
3452 struct inode
*new_dir
, struct dentry
*new_dentry
)
3454 struct inode
*target
= new_dentry
->d_inode
;
3457 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
3463 mutex_lock(&target
->i_mutex
);
3466 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
3469 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
3474 dont_mount(new_dentry
);
3475 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
3476 d_move(old_dentry
, new_dentry
);
3479 mutex_unlock(&target
->i_mutex
);
3484 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
3485 struct inode
*new_dir
, struct dentry
*new_dentry
)
3488 int is_dir
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
3489 const unsigned char *old_name
;
3491 if (old_dentry
->d_inode
== new_dentry
->d_inode
)
3494 error
= may_delete(old_dir
, old_dentry
, is_dir
);
3498 if (!new_dentry
->d_inode
)
3499 error
= may_create(new_dir
, new_dentry
);
3501 error
= may_delete(new_dir
, new_dentry
, is_dir
);
3505 if (!old_dir
->i_op
->rename
)
3508 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
3511 error
= vfs_rename_dir(old_dir
,old_dentry
,new_dir
,new_dentry
);
3513 error
= vfs_rename_other(old_dir
,old_dentry
,new_dir
,new_dentry
);
3515 fsnotify_move(old_dir
, new_dir
, old_name
, is_dir
,
3516 new_dentry
->d_inode
, old_dentry
);
3517 fsnotify_oldname_free(old_name
);
3522 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
3523 int, newdfd
, const char __user
*, newname
)
3525 struct dentry
*old_dir
, *new_dir
;
3526 struct dentry
*old_dentry
, *new_dentry
;
3527 struct dentry
*trap
;
3528 struct nameidata oldnd
, newnd
;
3533 error
= user_path_parent(olddfd
, oldname
, &oldnd
, &from
);
3537 error
= user_path_parent(newdfd
, newname
, &newnd
, &to
);
3542 if (oldnd
.path
.mnt
!= newnd
.path
.mnt
)
3545 old_dir
= oldnd
.path
.dentry
;
3547 if (oldnd
.last_type
!= LAST_NORM
)
3550 new_dir
= newnd
.path
.dentry
;
3551 if (newnd
.last_type
!= LAST_NORM
)
3554 oldnd
.flags
&= ~LOOKUP_PARENT
;
3555 newnd
.flags
&= ~LOOKUP_PARENT
;
3556 newnd
.flags
|= LOOKUP_RENAME_TARGET
;
3558 trap
= lock_rename(new_dir
, old_dir
);
3560 old_dentry
= lookup_hash(&oldnd
);
3561 error
= PTR_ERR(old_dentry
);
3562 if (IS_ERR(old_dentry
))
3564 /* source must exist */
3566 if (!old_dentry
->d_inode
)
3568 /* unless the source is a directory trailing slashes give -ENOTDIR */
3569 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
)) {
3571 if (oldnd
.last
.name
[oldnd
.last
.len
])
3573 if (newnd
.last
.name
[newnd
.last
.len
])
3576 /* source should not be ancestor of target */
3578 if (old_dentry
== trap
)
3580 new_dentry
= lookup_hash(&newnd
);
3581 error
= PTR_ERR(new_dentry
);
3582 if (IS_ERR(new_dentry
))
3584 /* target should not be an ancestor of source */
3586 if (new_dentry
== trap
)
3589 error
= mnt_want_write(oldnd
.path
.mnt
);
3592 error
= security_path_rename(&oldnd
.path
, old_dentry
,
3593 &newnd
.path
, new_dentry
);
3596 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
3597 new_dir
->d_inode
, new_dentry
);
3599 mnt_drop_write(oldnd
.path
.mnt
);
3605 unlock_rename(new_dir
, old_dir
);
3607 path_put(&newnd
.path
);
3610 path_put(&oldnd
.path
);
3616 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
3618 return sys_renameat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
);
3621 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
, const char *link
)
3625 len
= PTR_ERR(link
);
3630 if (len
> (unsigned) buflen
)
3632 if (copy_to_user(buffer
, link
, len
))
3639 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
3640 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
3641 * using) it for any given inode is up to filesystem.
3643 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
3645 struct nameidata nd
;
3650 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
3652 return PTR_ERR(cookie
);
3654 res
= vfs_readlink(dentry
, buffer
, buflen
, nd_get_link(&nd
));
3655 if (dentry
->d_inode
->i_op
->put_link
)
3656 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
3660 int vfs_follow_link(struct nameidata
*nd
, const char *link
)
3662 return __vfs_follow_link(nd
, link
);
3665 /* get the link contents into pagecache */
3666 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
3670 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
3671 page
= read_mapping_page(mapping
, 0, NULL
);
3676 nd_terminate_link(kaddr
, dentry
->d_inode
->i_size
, PAGE_SIZE
- 1);
3680 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
3682 struct page
*page
= NULL
;
3683 char *s
= page_getlink(dentry
, &page
);
3684 int res
= vfs_readlink(dentry
,buffer
,buflen
,s
);
3687 page_cache_release(page
);
3692 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
3694 struct page
*page
= NULL
;
3695 nd_set_link(nd
, page_getlink(dentry
, &page
));
3699 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
3701 struct page
*page
= cookie
;
3705 page_cache_release(page
);
3710 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
3712 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
3714 struct address_space
*mapping
= inode
->i_mapping
;
3719 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
3721 flags
|= AOP_FLAG_NOFS
;
3724 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
3725 flags
, &page
, &fsdata
);
3729 kaddr
= kmap_atomic(page
);
3730 memcpy(kaddr
, symname
, len
-1);
3731 kunmap_atomic(kaddr
);
3733 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
3740 mark_inode_dirty(inode
);
3746 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
3748 return __page_symlink(inode
, symname
, len
,
3749 !(mapping_gfp_mask(inode
->i_mapping
) & __GFP_FS
));
3752 const struct inode_operations page_symlink_inode_operations
= {
3753 .readlink
= generic_readlink
,
3754 .follow_link
= page_follow_link_light
,
3755 .put_link
= page_put_link
,
3758 EXPORT_SYMBOL(user_path_at
);
3759 EXPORT_SYMBOL(follow_down_one
);
3760 EXPORT_SYMBOL(follow_down
);
3761 EXPORT_SYMBOL(follow_up
);
3762 EXPORT_SYMBOL(get_write_access
); /* binfmt_aout */
3763 EXPORT_SYMBOL(getname
);
3764 EXPORT_SYMBOL(lock_rename
);
3765 EXPORT_SYMBOL(lookup_one_len
);
3766 EXPORT_SYMBOL(page_follow_link_light
);
3767 EXPORT_SYMBOL(page_put_link
);
3768 EXPORT_SYMBOL(page_readlink
);
3769 EXPORT_SYMBOL(__page_symlink
);
3770 EXPORT_SYMBOL(page_symlink
);
3771 EXPORT_SYMBOL(page_symlink_inode_operations
);
3772 EXPORT_SYMBOL(kern_path
);
3773 EXPORT_SYMBOL(vfs_path_lookup
);
3774 EXPORT_SYMBOL(inode_permission
);
3775 EXPORT_SYMBOL(unlock_rename
);
3776 EXPORT_SYMBOL(vfs_create
);
3777 EXPORT_SYMBOL(vfs_follow_link
);
3778 EXPORT_SYMBOL(vfs_link
);
3779 EXPORT_SYMBOL(vfs_mkdir
);
3780 EXPORT_SYMBOL(vfs_mknod
);
3781 EXPORT_SYMBOL(generic_permission
);
3782 EXPORT_SYMBOL(vfs_readlink
);
3783 EXPORT_SYMBOL(vfs_rename
);
3784 EXPORT_SYMBOL(vfs_rmdir
);
3785 EXPORT_SYMBOL(vfs_symlink
);
3786 EXPORT_SYMBOL(vfs_unlink
);
3787 EXPORT_SYMBOL(dentry_unhash
);
3788 EXPORT_SYMBOL(generic_readlink
);