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/quotaops.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 <asm/uaccess.h>
38 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
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-existant 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 static int __link_path_walk(const char *name
, struct nameidata
*nd
);
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 int do_getname(const char __user
*filename
, char *page
)
123 unsigned long len
= PATH_MAX
;
125 if (!segment_eq(get_fs(), KERNEL_DS
)) {
126 if ((unsigned long) filename
>= TASK_SIZE
)
128 if (TASK_SIZE
- (unsigned long) filename
< PATH_MAX
)
129 len
= TASK_SIZE
- (unsigned long) filename
;
132 retval
= strncpy_from_user(page
, filename
, len
);
136 return -ENAMETOOLONG
;
142 char * getname(const char __user
* filename
)
146 result
= ERR_PTR(-ENOMEM
);
149 int retval
= do_getname(filename
, tmp
);
154 result
= ERR_PTR(retval
);
157 audit_getname(result
);
161 #ifdef CONFIG_AUDITSYSCALL
162 void putname(const char *name
)
164 if (unlikely(!audit_dummy_context()))
169 EXPORT_SYMBOL(putname
);
174 * generic_permission - check for access rights on a Posix-like filesystem
175 * @inode: inode to check access rights for
176 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
177 * @check_acl: optional callback to check for Posix ACLs
179 * Used to check for read/write/execute permissions on a file.
180 * We use "fsuid" for this, letting us set arbitrary permissions
181 * for filesystem access without changing the "normal" uids which
182 * are used for other things..
184 int generic_permission(struct inode
*inode
, int mask
,
185 int (*check_acl
)(struct inode
*inode
, int mask
))
187 umode_t mode
= inode
->i_mode
;
189 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
191 if (current_fsuid() == inode
->i_uid
)
194 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
) && check_acl
) {
195 int error
= check_acl(inode
, mask
);
196 if (error
== -EACCES
)
197 goto check_capabilities
;
198 else if (error
!= -EAGAIN
)
202 if (in_group_p(inode
->i_gid
))
207 * If the DACs are ok we don't need any capability check.
209 if ((mask
& ~mode
) == 0)
214 * Read/write DACs are always overridable.
215 * Executable DACs are overridable if at least one exec bit is set.
217 if (!(mask
& MAY_EXEC
) || execute_ok(inode
))
218 if (capable(CAP_DAC_OVERRIDE
))
222 * Searching includes executable on directories, else just read.
224 if (mask
== MAY_READ
|| (S_ISDIR(inode
->i_mode
) && !(mask
& MAY_WRITE
)))
225 if (capable(CAP_DAC_READ_SEARCH
))
232 * inode_permission - check for access rights to a given inode
233 * @inode: inode to check permission on
234 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
236 * Used to check for read/write/execute permissions on an inode.
237 * We use "fsuid" for this, letting us set arbitrary permissions
238 * for filesystem access without changing the "normal" uids which
239 * are used for other things.
241 int inode_permission(struct inode
*inode
, int mask
)
245 if (mask
& MAY_WRITE
) {
246 umode_t mode
= inode
->i_mode
;
249 * Nobody gets write access to a read-only fs.
251 if (IS_RDONLY(inode
) &&
252 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
256 * Nobody gets write access to an immutable file.
258 if (IS_IMMUTABLE(inode
))
262 if (inode
->i_op
->permission
)
263 retval
= inode
->i_op
->permission(inode
, mask
);
265 retval
= generic_permission(inode
, mask
, NULL
);
270 retval
= devcgroup_inode_permission(inode
, mask
);
274 return security_inode_permission(inode
,
275 mask
& (MAY_READ
|MAY_WRITE
|MAY_EXEC
|MAY_APPEND
));
279 * file_permission - check for additional access rights to a given file
280 * @file: file to check access rights for
281 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
283 * Used to check for read/write/execute permissions on an already opened
287 * Do not use this function in new code. All access checks should
288 * be done using inode_permission().
290 int file_permission(struct file
*file
, int mask
)
292 return inode_permission(file
->f_path
.dentry
->d_inode
, mask
);
296 * get_write_access() gets write permission for a file.
297 * put_write_access() releases this write permission.
298 * This is used for regular files.
299 * We cannot support write (and maybe mmap read-write shared) accesses and
300 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
301 * can have the following values:
302 * 0: no writers, no VM_DENYWRITE mappings
303 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
304 * > 0: (i_writecount) users are writing to the file.
306 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
307 * except for the cases where we don't hold i_writecount yet. Then we need to
308 * use {get,deny}_write_access() - these functions check the sign and refuse
309 * to do the change if sign is wrong. Exclusion between them is provided by
310 * the inode->i_lock spinlock.
313 int get_write_access(struct inode
* inode
)
315 spin_lock(&inode
->i_lock
);
316 if (atomic_read(&inode
->i_writecount
) < 0) {
317 spin_unlock(&inode
->i_lock
);
320 atomic_inc(&inode
->i_writecount
);
321 spin_unlock(&inode
->i_lock
);
326 int deny_write_access(struct file
* file
)
328 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
330 spin_lock(&inode
->i_lock
);
331 if (atomic_read(&inode
->i_writecount
) > 0) {
332 spin_unlock(&inode
->i_lock
);
335 atomic_dec(&inode
->i_writecount
);
336 spin_unlock(&inode
->i_lock
);
342 * path_get - get a reference to a path
343 * @path: path to get the reference to
345 * Given a path increment the reference count to the dentry and the vfsmount.
347 void path_get(struct path
*path
)
352 EXPORT_SYMBOL(path_get
);
355 * path_put - put a reference to a path
356 * @path: path to put the reference to
358 * Given a path decrement the reference count to the dentry and the vfsmount.
360 void path_put(struct path
*path
)
365 EXPORT_SYMBOL(path_put
);
368 * release_open_intent - free up open intent resources
369 * @nd: pointer to nameidata
371 void release_open_intent(struct nameidata
*nd
)
373 if (nd
->intent
.open
.file
->f_path
.dentry
== NULL
)
374 put_filp(nd
->intent
.open
.file
);
376 fput(nd
->intent
.open
.file
);
379 static inline struct dentry
*
380 do_revalidate(struct dentry
*dentry
, struct nameidata
*nd
)
382 int status
= dentry
->d_op
->d_revalidate(dentry
, nd
);
383 if (unlikely(status
<= 0)) {
385 * The dentry failed validation.
386 * If d_revalidate returned 0 attempt to invalidate
387 * the dentry otherwise d_revalidate is asking us
388 * to return a fail status.
391 if (!d_invalidate(dentry
)) {
397 dentry
= ERR_PTR(status
);
404 * Internal lookup() using the new generic dcache.
407 static struct dentry
* cached_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
409 struct dentry
* dentry
= __d_lookup(parent
, name
);
411 /* lockess __d_lookup may fail due to concurrent d_move()
412 * in some unrelated directory, so try with d_lookup
415 dentry
= d_lookup(parent
, name
);
417 if (dentry
&& dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
418 dentry
= do_revalidate(dentry
, nd
);
424 * Short-cut version of permission(), for calling by
425 * path_walk(), when dcache lock is held. Combines parts
426 * of permission() and generic_permission(), and tests ONLY for
427 * MAY_EXEC permission.
429 * If appropriate, check DAC only. If not appropriate, or
430 * short-cut DAC fails, then call permission() to do more
431 * complete permission check.
433 static int exec_permission_lite(struct inode
*inode
)
435 umode_t mode
= inode
->i_mode
;
437 if (inode
->i_op
->permission
)
440 if (current_fsuid() == inode
->i_uid
)
442 else if (in_group_p(inode
->i_gid
))
448 if ((inode
->i_mode
& S_IXUGO
) && capable(CAP_DAC_OVERRIDE
))
451 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_OVERRIDE
))
454 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_READ_SEARCH
))
459 return security_inode_permission(inode
, MAY_EXEC
);
463 * This is called when everything else fails, and we actually have
464 * to go to the low-level filesystem to find out what we should do..
466 * We get the directory semaphore, and after getting that we also
467 * make sure that nobody added the entry to the dcache in the meantime..
470 static struct dentry
* real_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
472 struct dentry
* result
;
473 struct inode
*dir
= parent
->d_inode
;
475 mutex_lock(&dir
->i_mutex
);
477 * First re-do the cached lookup just in case it was created
478 * while we waited for the directory semaphore..
480 * FIXME! This could use version numbering or similar to
481 * avoid unnecessary cache lookups.
483 * The "dcache_lock" is purely to protect the RCU list walker
484 * from concurrent renames at this point (we mustn't get false
485 * negatives from the RCU list walk here, unlike the optimistic
488 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
490 result
= d_lookup(parent
, name
);
492 struct dentry
*dentry
;
494 /* Don't create child dentry for a dead directory. */
495 result
= ERR_PTR(-ENOENT
);
499 dentry
= d_alloc(parent
, name
);
500 result
= ERR_PTR(-ENOMEM
);
502 result
= dir
->i_op
->lookup(dir
, dentry
, nd
);
509 mutex_unlock(&dir
->i_mutex
);
514 * Uhhuh! Nasty case: the cache was re-populated while
515 * we waited on the semaphore. Need to revalidate.
517 mutex_unlock(&dir
->i_mutex
);
518 if (result
->d_op
&& result
->d_op
->d_revalidate
) {
519 result
= do_revalidate(result
, nd
);
521 result
= ERR_PTR(-ENOENT
);
527 * Wrapper to retry pathname resolution whenever the underlying
528 * file system returns an ESTALE.
530 * Retry the whole path once, forcing real lookup requests
531 * instead of relying on the dcache.
533 static __always_inline
int link_path_walk(const char *name
, struct nameidata
*nd
)
535 struct path save
= nd
->path
;
538 /* make sure the stuff we saved doesn't go away */
541 result
= __link_path_walk(name
, nd
);
542 if (result
== -ESTALE
) {
543 /* nd->path had been dropped */
546 nd
->flags
|= LOOKUP_REVAL
;
547 result
= __link_path_walk(name
, nd
);
555 static __always_inline
int __vfs_follow_link(struct nameidata
*nd
, const char *link
)
563 struct fs_struct
*fs
= current
->fs
;
567 read_lock(&fs
->lock
);
570 read_unlock(&fs
->lock
);
573 res
= link_path_walk(link
, nd
);
574 if (nd
->depth
|| res
|| nd
->last_type
!=LAST_NORM
)
577 * If it is an iterative symlinks resolution in open_namei() we
578 * have to copy the last component. And all that crap because of
579 * bloody create() on broken symlinks. Furrfu...
582 if (unlikely(!name
)) {
586 strcpy(name
, nd
->last
.name
);
587 nd
->last
.name
= name
;
591 return PTR_ERR(link
);
594 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
597 if (path
->mnt
!= nd
->path
.mnt
)
601 static inline void path_to_nameidata(struct path
*path
, struct nameidata
*nd
)
603 dput(nd
->path
.dentry
);
604 if (nd
->path
.mnt
!= path
->mnt
)
605 mntput(nd
->path
.mnt
);
606 nd
->path
.mnt
= path
->mnt
;
607 nd
->path
.dentry
= path
->dentry
;
610 static __always_inline
int __do_follow_link(struct path
*path
, struct nameidata
*nd
)
614 struct dentry
*dentry
= path
->dentry
;
616 touch_atime(path
->mnt
, dentry
);
617 nd_set_link(nd
, NULL
);
619 if (path
->mnt
!= nd
->path
.mnt
) {
620 path_to_nameidata(path
, nd
);
624 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
625 error
= PTR_ERR(cookie
);
626 if (!IS_ERR(cookie
)) {
627 char *s
= nd_get_link(nd
);
630 error
= __vfs_follow_link(nd
, s
);
631 if (dentry
->d_inode
->i_op
->put_link
)
632 dentry
->d_inode
->i_op
->put_link(dentry
, nd
, cookie
);
640 * This limits recursive symlink follows to 8, while
641 * limiting consecutive symlinks to 40.
643 * Without that kind of total limit, nasty chains of consecutive
644 * symlinks can cause almost arbitrarily long lookups.
646 static inline int do_follow_link(struct path
*path
, struct nameidata
*nd
)
649 if (current
->link_count
>= MAX_NESTED_LINKS
)
651 if (current
->total_link_count
>= 40)
653 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
655 err
= security_inode_follow_link(path
->dentry
, nd
);
658 current
->link_count
++;
659 current
->total_link_count
++;
661 err
= __do_follow_link(path
, nd
);
662 current
->link_count
--;
666 path_put_conditional(path
, nd
);
671 int follow_up(struct vfsmount
**mnt
, struct dentry
**dentry
)
673 struct vfsmount
*parent
;
674 struct dentry
*mountpoint
;
675 spin_lock(&vfsmount_lock
);
676 parent
=(*mnt
)->mnt_parent
;
677 if (parent
== *mnt
) {
678 spin_unlock(&vfsmount_lock
);
682 mountpoint
=dget((*mnt
)->mnt_mountpoint
);
683 spin_unlock(&vfsmount_lock
);
685 *dentry
= mountpoint
;
691 /* no need for dcache_lock, as serialization is taken care in
694 static int __follow_mount(struct path
*path
)
697 while (d_mountpoint(path
->dentry
)) {
698 struct vfsmount
*mounted
= lookup_mnt(path
->mnt
, path
->dentry
);
705 path
->dentry
= dget(mounted
->mnt_root
);
711 static void follow_mount(struct vfsmount
**mnt
, struct dentry
**dentry
)
713 while (d_mountpoint(*dentry
)) {
714 struct vfsmount
*mounted
= lookup_mnt(*mnt
, *dentry
);
720 *dentry
= dget(mounted
->mnt_root
);
724 /* no need for dcache_lock, as serialization is taken care in
727 int follow_down(struct vfsmount
**mnt
, struct dentry
**dentry
)
729 struct vfsmount
*mounted
;
731 mounted
= lookup_mnt(*mnt
, *dentry
);
736 *dentry
= dget(mounted
->mnt_root
);
742 static __always_inline
void follow_dotdot(struct nameidata
*nd
)
744 struct fs_struct
*fs
= current
->fs
;
747 struct vfsmount
*parent
;
748 struct dentry
*old
= nd
->path
.dentry
;
750 read_lock(&fs
->lock
);
751 if (nd
->path
.dentry
== fs
->root
.dentry
&&
752 nd
->path
.mnt
== fs
->root
.mnt
) {
753 read_unlock(&fs
->lock
);
756 read_unlock(&fs
->lock
);
757 spin_lock(&dcache_lock
);
758 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
759 nd
->path
.dentry
= dget(nd
->path
.dentry
->d_parent
);
760 spin_unlock(&dcache_lock
);
764 spin_unlock(&dcache_lock
);
765 spin_lock(&vfsmount_lock
);
766 parent
= nd
->path
.mnt
->mnt_parent
;
767 if (parent
== nd
->path
.mnt
) {
768 spin_unlock(&vfsmount_lock
);
772 nd
->path
.dentry
= dget(nd
->path
.mnt
->mnt_mountpoint
);
773 spin_unlock(&vfsmount_lock
);
775 mntput(nd
->path
.mnt
);
776 nd
->path
.mnt
= parent
;
778 follow_mount(&nd
->path
.mnt
, &nd
->path
.dentry
);
782 * It's more convoluted than I'd like it to be, but... it's still fairly
783 * small and for now I'd prefer to have fast path as straight as possible.
784 * It _is_ time-critical.
786 static int do_lookup(struct nameidata
*nd
, struct qstr
*name
,
789 struct vfsmount
*mnt
= nd
->path
.mnt
;
790 struct dentry
*dentry
= __d_lookup(nd
->path
.dentry
, name
);
794 if (dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
795 goto need_revalidate
;
798 path
->dentry
= dentry
;
799 __follow_mount(path
);
803 dentry
= real_lookup(nd
->path
.dentry
, name
, nd
);
809 dentry
= do_revalidate(dentry
, nd
);
817 return PTR_ERR(dentry
);
822 * This is the basic name resolution function, turning a pathname into
823 * the final dentry. We expect 'base' to be positive and a directory.
825 * Returns 0 and nd will have valid dentry and mnt on success.
826 * Returns error and drops reference to input namei data on failure.
828 static int __link_path_walk(const char *name
, struct nameidata
*nd
)
833 unsigned int lookup_flags
= nd
->flags
;
840 inode
= nd
->path
.dentry
->d_inode
;
842 lookup_flags
= LOOKUP_FOLLOW
| (nd
->flags
& LOOKUP_CONTINUE
);
844 /* At this point we know we have a real path component. */
850 nd
->flags
|= LOOKUP_CONTINUE
;
851 err
= exec_permission_lite(inode
);
853 err
= inode_permission(nd
->path
.dentry
->d_inode
,
856 err
= ima_path_check(&nd
->path
, MAY_EXEC
,
862 c
= *(const unsigned char *)name
;
864 hash
= init_name_hash();
867 hash
= partial_name_hash(c
, hash
);
868 c
= *(const unsigned char *)name
;
869 } while (c
&& (c
!= '/'));
870 this.len
= name
- (const char *) this.name
;
871 this.hash
= end_name_hash(hash
);
873 /* remove trailing slashes? */
876 while (*++name
== '/');
878 goto last_with_slashes
;
881 * "." and ".." are special - ".." especially so because it has
882 * to be able to know about the current root directory and
883 * parent relationships.
885 if (this.name
[0] == '.') switch (this.len
) {
889 if (this.name
[1] != '.')
892 inode
= nd
->path
.dentry
->d_inode
;
898 * See if the low-level filesystem might want
899 * to use its own hash..
901 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
902 err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
907 /* This does the actual lookups.. */
908 err
= do_lookup(nd
, &this, &next
);
913 inode
= next
.dentry
->d_inode
;
917 if (inode
->i_op
->follow_link
) {
918 err
= do_follow_link(&next
, nd
);
922 inode
= nd
->path
.dentry
->d_inode
;
926 path_to_nameidata(&next
, nd
);
928 if (!inode
->i_op
->lookup
)
931 /* here ends the main loop */
934 lookup_flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
936 /* Clear LOOKUP_CONTINUE iff it was previously unset */
937 nd
->flags
&= lookup_flags
| ~LOOKUP_CONTINUE
;
938 if (lookup_flags
& LOOKUP_PARENT
)
940 if (this.name
[0] == '.') switch (this.len
) {
944 if (this.name
[1] != '.')
947 inode
= nd
->path
.dentry
->d_inode
;
952 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
953 err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
958 err
= do_lookup(nd
, &this, &next
);
961 inode
= next
.dentry
->d_inode
;
962 if ((lookup_flags
& LOOKUP_FOLLOW
)
963 && inode
&& inode
->i_op
->follow_link
) {
964 err
= do_follow_link(&next
, nd
);
967 inode
= nd
->path
.dentry
->d_inode
;
969 path_to_nameidata(&next
, nd
);
973 if (lookup_flags
& LOOKUP_DIRECTORY
) {
975 if (!inode
->i_op
->lookup
)
981 nd
->last_type
= LAST_NORM
;
982 if (this.name
[0] != '.')
985 nd
->last_type
= LAST_DOT
;
986 else if (this.len
== 2 && this.name
[1] == '.')
987 nd
->last_type
= LAST_DOTDOT
;
992 * We bypassed the ordinary revalidation routines.
993 * We may need to check the cached dentry for staleness.
995 if (nd
->path
.dentry
&& nd
->path
.dentry
->d_sb
&&
996 (nd
->path
.dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
)) {
998 /* Note: we do not d_invalidate() */
999 if (!nd
->path
.dentry
->d_op
->d_revalidate(
1000 nd
->path
.dentry
, nd
))
1006 path_put_conditional(&next
, nd
);
1009 path_put(&nd
->path
);
1014 static int path_walk(const char *name
, struct nameidata
*nd
)
1016 current
->total_link_count
= 0;
1017 return link_path_walk(name
, nd
);
1020 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1021 static int do_path_lookup(int dfd
, const char *name
,
1022 unsigned int flags
, struct nameidata
*nd
)
1027 struct fs_struct
*fs
= current
->fs
;
1029 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1034 read_lock(&fs
->lock
);
1035 nd
->path
= fs
->root
;
1036 path_get(&fs
->root
);
1037 read_unlock(&fs
->lock
);
1038 } else if (dfd
== AT_FDCWD
) {
1039 read_lock(&fs
->lock
);
1042 read_unlock(&fs
->lock
);
1044 struct dentry
*dentry
;
1046 file
= fget_light(dfd
, &fput_needed
);
1051 dentry
= file
->f_path
.dentry
;
1054 if (!S_ISDIR(dentry
->d_inode
->i_mode
))
1057 retval
= file_permission(file
, MAY_EXEC
);
1061 nd
->path
= file
->f_path
;
1062 path_get(&file
->f_path
);
1064 fput_light(file
, fput_needed
);
1067 retval
= path_walk(name
, nd
);
1068 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1069 nd
->path
.dentry
->d_inode
))
1070 audit_inode(name
, nd
->path
.dentry
);
1075 fput_light(file
, fput_needed
);
1079 int path_lookup(const char *name
, unsigned int flags
,
1080 struct nameidata
*nd
)
1082 return do_path_lookup(AT_FDCWD
, name
, flags
, nd
);
1085 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
1087 struct nameidata nd
;
1088 int res
= do_path_lookup(AT_FDCWD
, name
, flags
, &nd
);
1095 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1096 * @dentry: pointer to dentry of the base directory
1097 * @mnt: pointer to vfs mount of the base directory
1098 * @name: pointer to file name
1099 * @flags: lookup flags
1100 * @nd: pointer to nameidata
1102 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
1103 const char *name
, unsigned int flags
,
1104 struct nameidata
*nd
)
1108 /* same as do_path_lookup */
1109 nd
->last_type
= LAST_ROOT
;
1113 nd
->path
.dentry
= dentry
;
1115 path_get(&nd
->path
);
1117 retval
= path_walk(name
, nd
);
1118 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1119 nd
->path
.dentry
->d_inode
))
1120 audit_inode(name
, nd
->path
.dentry
);
1127 * path_lookup_open - lookup a file path with open intent
1128 * @dfd: the directory to use as base, or AT_FDCWD
1129 * @name: pointer to file name
1130 * @lookup_flags: lookup intent flags
1131 * @nd: pointer to nameidata
1132 * @open_flags: open intent flags
1134 static int path_lookup_open(int dfd
, const char *name
,
1135 unsigned int lookup_flags
, struct nameidata
*nd
, int open_flags
)
1137 struct file
*filp
= get_empty_filp();
1142 nd
->intent
.open
.file
= filp
;
1143 nd
->intent
.open
.flags
= open_flags
;
1144 nd
->intent
.open
.create_mode
= 0;
1145 err
= do_path_lookup(dfd
, name
, lookup_flags
|LOOKUP_OPEN
, nd
);
1146 if (IS_ERR(nd
->intent
.open
.file
)) {
1148 err
= PTR_ERR(nd
->intent
.open
.file
);
1149 path_put(&nd
->path
);
1151 } else if (err
!= 0)
1152 release_open_intent(nd
);
1156 static struct dentry
*__lookup_hash(struct qstr
*name
,
1157 struct dentry
*base
, struct nameidata
*nd
)
1159 struct dentry
*dentry
;
1160 struct inode
*inode
;
1163 inode
= base
->d_inode
;
1166 * See if the low-level filesystem might want
1167 * to use its own hash..
1169 if (base
->d_op
&& base
->d_op
->d_hash
) {
1170 err
= base
->d_op
->d_hash(base
, name
);
1171 dentry
= ERR_PTR(err
);
1176 dentry
= cached_lookup(base
, name
, nd
);
1180 /* Don't create child dentry for a dead directory. */
1181 dentry
= ERR_PTR(-ENOENT
);
1182 if (IS_DEADDIR(inode
))
1185 new = d_alloc(base
, name
);
1186 dentry
= ERR_PTR(-ENOMEM
);
1189 dentry
= inode
->i_op
->lookup(inode
, new, nd
);
1200 * Restricted form of lookup. Doesn't follow links, single-component only,
1201 * needs parent already locked. Doesn't follow mounts.
1204 static struct dentry
*lookup_hash(struct nameidata
*nd
)
1208 err
= inode_permission(nd
->path
.dentry
->d_inode
, MAY_EXEC
);
1210 return ERR_PTR(err
);
1211 return __lookup_hash(&nd
->last
, nd
->path
.dentry
, nd
);
1214 static int __lookup_one_len(const char *name
, struct qstr
*this,
1215 struct dentry
*base
, int len
)
1225 hash
= init_name_hash();
1227 c
= *(const unsigned char *)name
++;
1228 if (c
== '/' || c
== '\0')
1230 hash
= partial_name_hash(c
, hash
);
1232 this->hash
= end_name_hash(hash
);
1237 * lookup_one_len - filesystem helper to lookup single pathname component
1238 * @name: pathname component to lookup
1239 * @base: base directory to lookup from
1240 * @len: maximum length @len should be interpreted to
1242 * Note that this routine is purely a helper for filesystem usage and should
1243 * not be called by generic code. Also note that by using this function the
1244 * nameidata argument is passed to the filesystem methods and a filesystem
1245 * using this helper needs to be prepared for that.
1247 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
1252 WARN_ON_ONCE(!mutex_is_locked(&base
->d_inode
->i_mutex
));
1254 err
= __lookup_one_len(name
, &this, base
, len
);
1256 return ERR_PTR(err
);
1258 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
1260 return ERR_PTR(err
);
1261 return __lookup_hash(&this, base
, NULL
);
1265 * lookup_one_noperm - bad hack for sysfs
1266 * @name: pathname component to lookup
1267 * @base: base directory to lookup from
1269 * This is a variant of lookup_one_len that doesn't perform any permission
1270 * checks. It's a horrible hack to work around the braindead sysfs
1271 * architecture and should not be used anywhere else.
1273 * DON'T USE THIS FUNCTION EVER, thanks.
1275 struct dentry
*lookup_one_noperm(const char *name
, struct dentry
*base
)
1280 err
= __lookup_one_len(name
, &this, base
, strlen(name
));
1282 return ERR_PTR(err
);
1283 return __lookup_hash(&this, base
, NULL
);
1286 int user_path_at(int dfd
, const char __user
*name
, unsigned flags
,
1289 struct nameidata nd
;
1290 char *tmp
= getname(name
);
1291 int err
= PTR_ERR(tmp
);
1294 BUG_ON(flags
& LOOKUP_PARENT
);
1296 err
= do_path_lookup(dfd
, tmp
, flags
, &nd
);
1304 static int user_path_parent(int dfd
, const char __user
*path
,
1305 struct nameidata
*nd
, char **name
)
1307 char *s
= getname(path
);
1313 error
= do_path_lookup(dfd
, s
, LOOKUP_PARENT
, nd
);
1323 * It's inline, so penalty for filesystems that don't use sticky bit is
1326 static inline int check_sticky(struct inode
*dir
, struct inode
*inode
)
1328 uid_t fsuid
= current_fsuid();
1330 if (!(dir
->i_mode
& S_ISVTX
))
1332 if (inode
->i_uid
== fsuid
)
1334 if (dir
->i_uid
== fsuid
)
1336 return !capable(CAP_FOWNER
);
1340 * Check whether we can remove a link victim from directory dir, check
1341 * whether the type of victim is right.
1342 * 1. We can't do it if dir is read-only (done in permission())
1343 * 2. We should have write and exec permissions on dir
1344 * 3. We can't remove anything from append-only dir
1345 * 4. We can't do anything with immutable dir (done in permission())
1346 * 5. If the sticky bit on dir is set we should either
1347 * a. be owner of dir, or
1348 * b. be owner of victim, or
1349 * c. have CAP_FOWNER capability
1350 * 6. If the victim is append-only or immutable we can't do antyhing with
1351 * links pointing to it.
1352 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1353 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1354 * 9. We can't remove a root or mountpoint.
1355 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1356 * nfs_async_unlink().
1358 static int may_delete(struct inode
*dir
,struct dentry
*victim
,int isdir
)
1362 if (!victim
->d_inode
)
1365 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
1366 audit_inode_child(victim
->d_name
.name
, victim
, dir
);
1368 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
1373 if (check_sticky(dir
, victim
->d_inode
)||IS_APPEND(victim
->d_inode
)||
1374 IS_IMMUTABLE(victim
->d_inode
) || IS_SWAPFILE(victim
->d_inode
))
1377 if (!S_ISDIR(victim
->d_inode
->i_mode
))
1379 if (IS_ROOT(victim
))
1381 } else if (S_ISDIR(victim
->d_inode
->i_mode
))
1383 if (IS_DEADDIR(dir
))
1385 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
1390 /* Check whether we can create an object with dentry child in directory
1392 * 1. We can't do it if child already exists (open has special treatment for
1393 * this case, but since we are inlined it's OK)
1394 * 2. We can't do it if dir is read-only (done in permission())
1395 * 3. We should have write and exec permissions on dir
1396 * 4. We can't do it if dir is immutable (done in permission())
1398 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
1402 if (IS_DEADDIR(dir
))
1404 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
1408 * O_DIRECTORY translates into forcing a directory lookup.
1410 static inline int lookup_flags(unsigned int f
)
1412 unsigned long retval
= LOOKUP_FOLLOW
;
1415 retval
&= ~LOOKUP_FOLLOW
;
1417 if (f
& O_DIRECTORY
)
1418 retval
|= LOOKUP_DIRECTORY
;
1424 * p1 and p2 should be directories on the same fs.
1426 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
1431 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1435 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1437 p
= d_ancestor(p2
, p1
);
1439 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1440 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1444 p
= d_ancestor(p1
, p2
);
1446 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1447 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1451 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1452 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1456 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
1458 mutex_unlock(&p1
->d_inode
->i_mutex
);
1460 mutex_unlock(&p2
->d_inode
->i_mutex
);
1461 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1465 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1466 struct nameidata
*nd
)
1468 int error
= may_create(dir
, dentry
);
1473 if (!dir
->i_op
->create
)
1474 return -EACCES
; /* shouldn't it be ENOSYS? */
1477 error
= security_inode_create(dir
, dentry
, mode
);
1481 error
= dir
->i_op
->create(dir
, dentry
, mode
, nd
);
1483 fsnotify_create(dir
, dentry
);
1487 int may_open(struct path
*path
, int acc_mode
, int flag
)
1489 struct dentry
*dentry
= path
->dentry
;
1490 struct inode
*inode
= dentry
->d_inode
;
1496 switch (inode
->i_mode
& S_IFMT
) {
1500 if (acc_mode
& MAY_WRITE
)
1505 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
1514 error
= inode_permission(inode
, acc_mode
);
1518 error
= ima_path_check(path
,
1519 acc_mode
& (MAY_READ
| MAY_WRITE
| MAY_EXEC
),
1524 * An append-only file must be opened in append mode for writing.
1526 if (IS_APPEND(inode
)) {
1527 if ((flag
& FMODE_WRITE
) && !(flag
& O_APPEND
))
1533 /* O_NOATIME can only be set by the owner or superuser */
1534 if (flag
& O_NOATIME
)
1535 if (!is_owner_or_cap(inode
))
1539 * Ensure there are no outstanding leases on the file.
1541 error
= break_lease(inode
, flag
);
1545 if (flag
& O_TRUNC
) {
1546 error
= get_write_access(inode
);
1551 * Refuse to truncate files with mandatory locks held on them.
1553 error
= locks_verify_locked(inode
);
1555 error
= security_path_truncate(path
, 0,
1556 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
);
1560 error
= do_truncate(dentry
, 0,
1561 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
1564 put_write_access(inode
);
1568 if (flag
& FMODE_WRITE
)
1575 * Be careful about ever adding any more callers of this
1576 * function. Its flags must be in the namei format, not
1577 * what get passed to sys_open().
1579 static int __open_namei_create(struct nameidata
*nd
, struct path
*path
,
1583 struct dentry
*dir
= nd
->path
.dentry
;
1585 if (!IS_POSIXACL(dir
->d_inode
))
1586 mode
&= ~current_umask();
1587 error
= security_path_mknod(&nd
->path
, path
->dentry
, mode
, 0);
1590 error
= vfs_create(dir
->d_inode
, path
->dentry
, mode
, nd
);
1592 mutex_unlock(&dir
->d_inode
->i_mutex
);
1593 dput(nd
->path
.dentry
);
1594 nd
->path
.dentry
= path
->dentry
;
1597 /* Don't check for write permission, don't truncate */
1598 return may_open(&nd
->path
, 0, flag
& ~O_TRUNC
);
1602 * Note that while the flag value (low two bits) for sys_open means:
1607 * it is changed into
1608 * 00 - no permissions needed
1609 * 01 - read-permission
1610 * 10 - write-permission
1612 * for the internal routines (ie open_namei()/follow_link() etc)
1613 * This is more logical, and also allows the 00 "no perm needed"
1614 * to be used for symlinks (where the permissions are checked
1618 static inline int open_to_namei_flags(int flag
)
1620 if ((flag
+1) & O_ACCMODE
)
1625 static int open_will_write_to_fs(int flag
, struct inode
*inode
)
1628 * We'll never write to the fs underlying
1631 if (special_file(inode
->i_mode
))
1633 return (flag
& O_TRUNC
);
1637 * Note that the low bits of the passed in "open_flag"
1638 * are not the same as in the local variable "flag". See
1639 * open_to_namei_flags() for more details.
1641 struct file
*do_filp_open(int dfd
, const char *pathname
,
1642 int open_flag
, int mode
, int acc_mode
)
1645 struct nameidata nd
;
1651 int flag
= open_to_namei_flags(open_flag
);
1654 acc_mode
= MAY_OPEN
| ACC_MODE(flag
);
1656 /* O_TRUNC implies we need access checks for write permissions */
1658 acc_mode
|= MAY_WRITE
;
1660 /* Allow the LSM permission hook to distinguish append
1661 access from general write access. */
1662 if (flag
& O_APPEND
)
1663 acc_mode
|= MAY_APPEND
;
1666 * The simplest case - just a plain lookup.
1668 if (!(flag
& O_CREAT
)) {
1669 error
= path_lookup_open(dfd
, pathname
, lookup_flags(flag
),
1672 return ERR_PTR(error
);
1677 * Create - we need to know the parent.
1679 error
= do_path_lookup(dfd
, pathname
, LOOKUP_PARENT
, &nd
);
1681 return ERR_PTR(error
);
1684 * We have the parent and last component. First of all, check
1685 * that we are not asked to creat(2) an obvious directory - that
1689 if (nd
.last_type
!= LAST_NORM
|| nd
.last
.name
[nd
.last
.len
])
1693 filp
= get_empty_filp();
1696 nd
.intent
.open
.file
= filp
;
1697 nd
.intent
.open
.flags
= flag
;
1698 nd
.intent
.open
.create_mode
= mode
;
1699 dir
= nd
.path
.dentry
;
1700 nd
.flags
&= ~LOOKUP_PARENT
;
1701 nd
.flags
|= LOOKUP_CREATE
| LOOKUP_OPEN
;
1703 nd
.flags
|= LOOKUP_EXCL
;
1704 mutex_lock(&dir
->d_inode
->i_mutex
);
1705 path
.dentry
= lookup_hash(&nd
);
1706 path
.mnt
= nd
.path
.mnt
;
1709 error
= PTR_ERR(path
.dentry
);
1710 if (IS_ERR(path
.dentry
)) {
1711 mutex_unlock(&dir
->d_inode
->i_mutex
);
1715 if (IS_ERR(nd
.intent
.open
.file
)) {
1716 error
= PTR_ERR(nd
.intent
.open
.file
);
1717 goto exit_mutex_unlock
;
1720 /* Negative dentry, just create the file */
1721 if (!path
.dentry
->d_inode
) {
1723 * This write is needed to ensure that a
1724 * ro->rw transition does not occur between
1725 * the time when the file is created and when
1726 * a permanent write count is taken through
1727 * the 'struct file' in nameidata_to_filp().
1729 error
= mnt_want_write(nd
.path
.mnt
);
1731 goto exit_mutex_unlock
;
1732 error
= __open_namei_create(&nd
, &path
, flag
, mode
);
1734 mnt_drop_write(nd
.path
.mnt
);
1737 filp
= nameidata_to_filp(&nd
, open_flag
);
1738 mnt_drop_write(nd
.path
.mnt
);
1743 * It already exists.
1745 mutex_unlock(&dir
->d_inode
->i_mutex
);
1746 audit_inode(pathname
, path
.dentry
);
1752 if (__follow_mount(&path
)) {
1754 if (flag
& O_NOFOLLOW
)
1759 if (!path
.dentry
->d_inode
)
1761 if (path
.dentry
->d_inode
->i_op
->follow_link
)
1764 path_to_nameidata(&path
, &nd
);
1766 if (path
.dentry
->d_inode
&& S_ISDIR(path
.dentry
->d_inode
->i_mode
))
1771 * 1. may_open() truncates a file
1772 * 2. a rw->ro mount transition occurs
1773 * 3. nameidata_to_filp() fails due to
1775 * That would be inconsistent, and should
1776 * be avoided. Taking this mnt write here
1777 * ensures that (2) can not occur.
1779 will_write
= open_will_write_to_fs(flag
, nd
.path
.dentry
->d_inode
);
1781 error
= mnt_want_write(nd
.path
.mnt
);
1785 error
= may_open(&nd
.path
, acc_mode
, flag
);
1788 mnt_drop_write(nd
.path
.mnt
);
1791 filp
= nameidata_to_filp(&nd
, open_flag
);
1793 * It is now safe to drop the mnt write
1794 * because the filp has had a write taken
1798 mnt_drop_write(nd
.path
.mnt
);
1802 mutex_unlock(&dir
->d_inode
->i_mutex
);
1804 path_put_conditional(&path
, &nd
);
1806 if (!IS_ERR(nd
.intent
.open
.file
))
1807 release_open_intent(&nd
);
1810 return ERR_PTR(error
);
1814 if (flag
& O_NOFOLLOW
)
1817 * This is subtle. Instead of calling do_follow_link() we do the
1818 * thing by hands. The reason is that this way we have zero link_count
1819 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1820 * After that we have the parent and last component, i.e.
1821 * we are in the same situation as after the first path_walk().
1822 * Well, almost - if the last component is normal we get its copy
1823 * stored in nd->last.name and we will have to putname() it when we
1824 * are done. Procfs-like symlinks just set LAST_BIND.
1826 nd
.flags
|= LOOKUP_PARENT
;
1827 error
= security_inode_follow_link(path
.dentry
, &nd
);
1830 error
= __do_follow_link(&path
, &nd
);
1832 /* Does someone understand code flow here? Or it is only
1833 * me so stupid? Anathema to whoever designed this non-sense
1834 * with "intent.open".
1836 release_open_intent(&nd
);
1837 return ERR_PTR(error
);
1839 nd
.flags
&= ~LOOKUP_PARENT
;
1840 if (nd
.last_type
== LAST_BIND
)
1843 if (nd
.last_type
!= LAST_NORM
)
1845 if (nd
.last
.name
[nd
.last
.len
]) {
1846 __putname(nd
.last
.name
);
1851 __putname(nd
.last
.name
);
1854 dir
= nd
.path
.dentry
;
1855 mutex_lock(&dir
->d_inode
->i_mutex
);
1856 path
.dentry
= lookup_hash(&nd
);
1857 path
.mnt
= nd
.path
.mnt
;
1858 __putname(nd
.last
.name
);
1863 * filp_open - open file and return file pointer
1865 * @filename: path to open
1866 * @flags: open flags as per the open(2) second argument
1867 * @mode: mode for the new file if O_CREAT is set, else ignored
1869 * This is the helper to open a file from kernelspace if you really
1870 * have to. But in generally you should not do this, so please move
1871 * along, nothing to see here..
1873 struct file
*filp_open(const char *filename
, int flags
, int mode
)
1875 return do_filp_open(AT_FDCWD
, filename
, flags
, mode
, 0);
1877 EXPORT_SYMBOL(filp_open
);
1880 * lookup_create - lookup a dentry, creating it if it doesn't exist
1881 * @nd: nameidata info
1882 * @is_dir: directory flag
1884 * Simple function to lookup and return a dentry and create it
1885 * if it doesn't exist. Is SMP-safe.
1887 * Returns with nd->path.dentry->d_inode->i_mutex locked.
1889 struct dentry
*lookup_create(struct nameidata
*nd
, int is_dir
)
1891 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
1893 mutex_lock_nested(&nd
->path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1895 * Yucky last component or no last component at all?
1896 * (foo/., foo/.., /////)
1898 if (nd
->last_type
!= LAST_NORM
)
1900 nd
->flags
&= ~LOOKUP_PARENT
;
1901 nd
->flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
1902 nd
->intent
.open
.flags
= O_EXCL
;
1905 * Do the final lookup.
1907 dentry
= lookup_hash(nd
);
1911 if (dentry
->d_inode
)
1914 * Special case - lookup gave negative, but... we had foo/bar/
1915 * From the vfs_mknod() POV we just have a negative dentry -
1916 * all is fine. Let's be bastards - you had / on the end, you've
1917 * been asking for (non-existent) directory. -ENOENT for you.
1919 if (unlikely(!is_dir
&& nd
->last
.name
[nd
->last
.len
])) {
1921 dentry
= ERR_PTR(-ENOENT
);
1926 dentry
= ERR_PTR(-EEXIST
);
1930 EXPORT_SYMBOL_GPL(lookup_create
);
1932 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1934 int error
= may_create(dir
, dentry
);
1939 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
1942 if (!dir
->i_op
->mknod
)
1945 error
= devcgroup_inode_mknod(mode
, dev
);
1949 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
1954 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
1956 fsnotify_create(dir
, dentry
);
1960 static int may_mknod(mode_t mode
)
1962 switch (mode
& S_IFMT
) {
1968 case 0: /* zero mode translates to S_IFREG */
1977 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, int, mode
,
1982 struct dentry
*dentry
;
1983 struct nameidata nd
;
1988 error
= user_path_parent(dfd
, filename
, &nd
, &tmp
);
1992 dentry
= lookup_create(&nd
, 0);
1993 if (IS_ERR(dentry
)) {
1994 error
= PTR_ERR(dentry
);
1997 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
1998 mode
&= ~current_umask();
1999 error
= may_mknod(mode
);
2002 error
= mnt_want_write(nd
.path
.mnt
);
2005 error
= security_path_mknod(&nd
.path
, dentry
, mode
, dev
);
2007 goto out_drop_write
;
2008 switch (mode
& S_IFMT
) {
2009 case 0: case S_IFREG
:
2010 error
= vfs_create(nd
.path
.dentry
->d_inode
,dentry
,mode
,&nd
);
2012 case S_IFCHR
: case S_IFBLK
:
2013 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,
2014 new_decode_dev(dev
));
2016 case S_IFIFO
: case S_IFSOCK
:
2017 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,0);
2021 mnt_drop_write(nd
.path
.mnt
);
2025 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2032 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, int, mode
, unsigned, dev
)
2034 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
2037 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
2039 int error
= may_create(dir
, dentry
);
2044 if (!dir
->i_op
->mkdir
)
2047 mode
&= (S_IRWXUGO
|S_ISVTX
);
2048 error
= security_inode_mkdir(dir
, dentry
, mode
);
2053 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
2055 fsnotify_mkdir(dir
, dentry
);
2059 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, int, mode
)
2063 struct dentry
*dentry
;
2064 struct nameidata nd
;
2066 error
= user_path_parent(dfd
, pathname
, &nd
, &tmp
);
2070 dentry
= lookup_create(&nd
, 1);
2071 error
= PTR_ERR(dentry
);
2075 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2076 mode
&= ~current_umask();
2077 error
= mnt_want_write(nd
.path
.mnt
);
2080 error
= security_path_mkdir(&nd
.path
, dentry
, mode
);
2082 goto out_drop_write
;
2083 error
= vfs_mkdir(nd
.path
.dentry
->d_inode
, dentry
, mode
);
2085 mnt_drop_write(nd
.path
.mnt
);
2089 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2096 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, int, mode
)
2098 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
2102 * We try to drop the dentry early: we should have
2103 * a usage count of 2 if we're the only user of this
2104 * dentry, and if that is true (possibly after pruning
2105 * the dcache), then we drop the dentry now.
2107 * A low-level filesystem can, if it choses, legally
2110 * if (!d_unhashed(dentry))
2113 * if it cannot handle the case of removing a directory
2114 * that is still in use by something else..
2116 void dentry_unhash(struct dentry
*dentry
)
2119 shrink_dcache_parent(dentry
);
2120 spin_lock(&dcache_lock
);
2121 spin_lock(&dentry
->d_lock
);
2122 if (atomic_read(&dentry
->d_count
) == 2)
2124 spin_unlock(&dentry
->d_lock
);
2125 spin_unlock(&dcache_lock
);
2128 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2130 int error
= may_delete(dir
, dentry
, 1);
2135 if (!dir
->i_op
->rmdir
)
2140 mutex_lock(&dentry
->d_inode
->i_mutex
);
2141 dentry_unhash(dentry
);
2142 if (d_mountpoint(dentry
))
2145 error
= security_inode_rmdir(dir
, dentry
);
2147 error
= dir
->i_op
->rmdir(dir
, dentry
);
2149 dentry
->d_inode
->i_flags
|= S_DEAD
;
2152 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2161 static long do_rmdir(int dfd
, const char __user
*pathname
)
2165 struct dentry
*dentry
;
2166 struct nameidata nd
;
2168 error
= user_path_parent(dfd
, pathname
, &nd
, &name
);
2172 switch(nd
.last_type
) {
2184 nd
.flags
&= ~LOOKUP_PARENT
;
2186 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2187 dentry
= lookup_hash(&nd
);
2188 error
= PTR_ERR(dentry
);
2191 error
= mnt_want_write(nd
.path
.mnt
);
2194 error
= security_path_rmdir(&nd
.path
, dentry
);
2197 error
= vfs_rmdir(nd
.path
.dentry
->d_inode
, dentry
);
2199 mnt_drop_write(nd
.path
.mnt
);
2203 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2210 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
2212 return do_rmdir(AT_FDCWD
, pathname
);
2215 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
)
2217 int error
= may_delete(dir
, dentry
, 0);
2222 if (!dir
->i_op
->unlink
)
2227 mutex_lock(&dentry
->d_inode
->i_mutex
);
2228 if (d_mountpoint(dentry
))
2231 error
= security_inode_unlink(dir
, dentry
);
2233 error
= dir
->i_op
->unlink(dir
, dentry
);
2235 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2237 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2238 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
2239 fsnotify_link_count(dentry
->d_inode
);
2247 * Make sure that the actual truncation of the file will occur outside its
2248 * directory's i_mutex. Truncate can take a long time if there is a lot of
2249 * writeout happening, and we don't want to prevent access to the directory
2250 * while waiting on the I/O.
2252 static long do_unlinkat(int dfd
, const char __user
*pathname
)
2256 struct dentry
*dentry
;
2257 struct nameidata nd
;
2258 struct inode
*inode
= NULL
;
2260 error
= user_path_parent(dfd
, pathname
, &nd
, &name
);
2265 if (nd
.last_type
!= LAST_NORM
)
2268 nd
.flags
&= ~LOOKUP_PARENT
;
2270 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2271 dentry
= lookup_hash(&nd
);
2272 error
= PTR_ERR(dentry
);
2273 if (!IS_ERR(dentry
)) {
2274 /* Why not before? Because we want correct error value */
2275 if (nd
.last
.name
[nd
.last
.len
])
2277 inode
= dentry
->d_inode
;
2279 atomic_inc(&inode
->i_count
);
2280 error
= mnt_want_write(nd
.path
.mnt
);
2283 error
= security_path_unlink(&nd
.path
, dentry
);
2286 error
= vfs_unlink(nd
.path
.dentry
->d_inode
, dentry
);
2288 mnt_drop_write(nd
.path
.mnt
);
2292 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2294 iput(inode
); /* truncate the inode here */
2301 error
= !dentry
->d_inode
? -ENOENT
:
2302 S_ISDIR(dentry
->d_inode
->i_mode
) ? -EISDIR
: -ENOTDIR
;
2306 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
2308 if ((flag
& ~AT_REMOVEDIR
) != 0)
2311 if (flag
& AT_REMOVEDIR
)
2312 return do_rmdir(dfd
, pathname
);
2314 return do_unlinkat(dfd
, pathname
);
2317 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
2319 return do_unlinkat(AT_FDCWD
, pathname
);
2322 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
2324 int error
= may_create(dir
, dentry
);
2329 if (!dir
->i_op
->symlink
)
2332 error
= security_inode_symlink(dir
, dentry
, oldname
);
2337 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
2339 fsnotify_create(dir
, dentry
);
2343 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
2344 int, newdfd
, const char __user
*, newname
)
2349 struct dentry
*dentry
;
2350 struct nameidata nd
;
2352 from
= getname(oldname
);
2354 return PTR_ERR(from
);
2356 error
= user_path_parent(newdfd
, newname
, &nd
, &to
);
2360 dentry
= lookup_create(&nd
, 0);
2361 error
= PTR_ERR(dentry
);
2365 error
= mnt_want_write(nd
.path
.mnt
);
2368 error
= security_path_symlink(&nd
.path
, dentry
, from
);
2370 goto out_drop_write
;
2371 error
= vfs_symlink(nd
.path
.dentry
->d_inode
, dentry
, from
);
2373 mnt_drop_write(nd
.path
.mnt
);
2377 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2385 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
2387 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
2390 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
)
2392 struct inode
*inode
= old_dentry
->d_inode
;
2398 error
= may_create(dir
, new_dentry
);
2402 if (dir
->i_sb
!= inode
->i_sb
)
2406 * A link to an append-only or immutable file cannot be created.
2408 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
2410 if (!dir
->i_op
->link
)
2412 if (S_ISDIR(inode
->i_mode
))
2415 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
2419 mutex_lock(&inode
->i_mutex
);
2421 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
2422 mutex_unlock(&inode
->i_mutex
);
2424 fsnotify_link(dir
, inode
, new_dentry
);
2429 * Hardlinks are often used in delicate situations. We avoid
2430 * security-related surprises by not following symlinks on the
2433 * We don't follow them on the oldname either to be compatible
2434 * with linux 2.0, and to avoid hard-linking to directories
2435 * and other special files. --ADM
2437 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
2438 int, newdfd
, const char __user
*, newname
, int, flags
)
2440 struct dentry
*new_dentry
;
2441 struct nameidata nd
;
2442 struct path old_path
;
2446 if ((flags
& ~AT_SYMLINK_FOLLOW
) != 0)
2449 error
= user_path_at(olddfd
, oldname
,
2450 flags
& AT_SYMLINK_FOLLOW
? LOOKUP_FOLLOW
: 0,
2455 error
= user_path_parent(newdfd
, newname
, &nd
, &to
);
2459 if (old_path
.mnt
!= nd
.path
.mnt
)
2461 new_dentry
= lookup_create(&nd
, 0);
2462 error
= PTR_ERR(new_dentry
);
2463 if (IS_ERR(new_dentry
))
2465 error
= mnt_want_write(nd
.path
.mnt
);
2468 error
= security_path_link(old_path
.dentry
, &nd
.path
, new_dentry
);
2470 goto out_drop_write
;
2471 error
= vfs_link(old_path
.dentry
, nd
.path
.dentry
->d_inode
, new_dentry
);
2473 mnt_drop_write(nd
.path
.mnt
);
2477 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2482 path_put(&old_path
);
2487 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
2489 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
2493 * The worst of all namespace operations - renaming directory. "Perverted"
2494 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2496 * a) we can get into loop creation. Check is done in is_subdir().
2497 * b) race potential - two innocent renames can create a loop together.
2498 * That's where 4.4 screws up. Current fix: serialization on
2499 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2501 * c) we have to lock _three_ objects - parents and victim (if it exists).
2502 * And that - after we got ->i_mutex on parents (until then we don't know
2503 * whether the target exists). Solution: try to be smart with locking
2504 * order for inodes. We rely on the fact that tree topology may change
2505 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2506 * move will be locked. Thus we can rank directories by the tree
2507 * (ancestors first) and rank all non-directories after them.
2508 * That works since everybody except rename does "lock parent, lookup,
2509 * lock child" and rename is under ->s_vfs_rename_mutex.
2510 * HOWEVER, it relies on the assumption that any object with ->lookup()
2511 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2512 * we'd better make sure that there's no link(2) for them.
2513 * d) some filesystems don't support opened-but-unlinked directories,
2514 * either because of layout or because they are not ready to deal with
2515 * all cases correctly. The latter will be fixed (taking this sort of
2516 * stuff into VFS), but the former is not going away. Solution: the same
2517 * trick as in rmdir().
2518 * e) conversion from fhandle to dentry may come in the wrong moment - when
2519 * we are removing the target. Solution: we will have to grab ->i_mutex
2520 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2521 * ->i_mutex on parents, which works but leads to some truely excessive
2524 static int vfs_rename_dir(struct inode
*old_dir
, struct dentry
*old_dentry
,
2525 struct inode
*new_dir
, struct dentry
*new_dentry
)
2528 struct inode
*target
;
2531 * If we are going to change the parent - check write permissions,
2532 * we'll need to flip '..'.
2534 if (new_dir
!= old_dir
) {
2535 error
= inode_permission(old_dentry
->d_inode
, MAY_WRITE
);
2540 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2544 target
= new_dentry
->d_inode
;
2546 mutex_lock(&target
->i_mutex
);
2547 dentry_unhash(new_dentry
);
2549 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2552 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2555 target
->i_flags
|= S_DEAD
;
2556 mutex_unlock(&target
->i_mutex
);
2557 if (d_unhashed(new_dentry
))
2558 d_rehash(new_dentry
);
2562 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2563 d_move(old_dentry
,new_dentry
);
2567 static int vfs_rename_other(struct inode
*old_dir
, struct dentry
*old_dentry
,
2568 struct inode
*new_dir
, struct dentry
*new_dentry
)
2570 struct inode
*target
;
2573 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2578 target
= new_dentry
->d_inode
;
2580 mutex_lock(&target
->i_mutex
);
2581 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2584 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2586 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2587 d_move(old_dentry
, new_dentry
);
2590 mutex_unlock(&target
->i_mutex
);
2595 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2596 struct inode
*new_dir
, struct dentry
*new_dentry
)
2599 int is_dir
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
2600 const char *old_name
;
2602 if (old_dentry
->d_inode
== new_dentry
->d_inode
)
2605 error
= may_delete(old_dir
, old_dentry
, is_dir
);
2609 if (!new_dentry
->d_inode
)
2610 error
= may_create(new_dir
, new_dentry
);
2612 error
= may_delete(new_dir
, new_dentry
, is_dir
);
2616 if (!old_dir
->i_op
->rename
)
2619 vfs_dq_init(old_dir
);
2620 vfs_dq_init(new_dir
);
2622 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
2625 error
= vfs_rename_dir(old_dir
,old_dentry
,new_dir
,new_dentry
);
2627 error
= vfs_rename_other(old_dir
,old_dentry
,new_dir
,new_dentry
);
2629 const char *new_name
= old_dentry
->d_name
.name
;
2630 fsnotify_move(old_dir
, new_dir
, old_name
, new_name
, is_dir
,
2631 new_dentry
->d_inode
, old_dentry
);
2633 fsnotify_oldname_free(old_name
);
2638 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
2639 int, newdfd
, const char __user
*, newname
)
2641 struct dentry
*old_dir
, *new_dir
;
2642 struct dentry
*old_dentry
, *new_dentry
;
2643 struct dentry
*trap
;
2644 struct nameidata oldnd
, newnd
;
2649 error
= user_path_parent(olddfd
, oldname
, &oldnd
, &from
);
2653 error
= user_path_parent(newdfd
, newname
, &newnd
, &to
);
2658 if (oldnd
.path
.mnt
!= newnd
.path
.mnt
)
2661 old_dir
= oldnd
.path
.dentry
;
2663 if (oldnd
.last_type
!= LAST_NORM
)
2666 new_dir
= newnd
.path
.dentry
;
2667 if (newnd
.last_type
!= LAST_NORM
)
2670 oldnd
.flags
&= ~LOOKUP_PARENT
;
2671 newnd
.flags
&= ~LOOKUP_PARENT
;
2672 newnd
.flags
|= LOOKUP_RENAME_TARGET
;
2674 trap
= lock_rename(new_dir
, old_dir
);
2676 old_dentry
= lookup_hash(&oldnd
);
2677 error
= PTR_ERR(old_dentry
);
2678 if (IS_ERR(old_dentry
))
2680 /* source must exist */
2682 if (!old_dentry
->d_inode
)
2684 /* unless the source is a directory trailing slashes give -ENOTDIR */
2685 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
)) {
2687 if (oldnd
.last
.name
[oldnd
.last
.len
])
2689 if (newnd
.last
.name
[newnd
.last
.len
])
2692 /* source should not be ancestor of target */
2694 if (old_dentry
== trap
)
2696 new_dentry
= lookup_hash(&newnd
);
2697 error
= PTR_ERR(new_dentry
);
2698 if (IS_ERR(new_dentry
))
2700 /* target should not be an ancestor of source */
2702 if (new_dentry
== trap
)
2705 error
= mnt_want_write(oldnd
.path
.mnt
);
2708 error
= security_path_rename(&oldnd
.path
, old_dentry
,
2709 &newnd
.path
, new_dentry
);
2712 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
2713 new_dir
->d_inode
, new_dentry
);
2715 mnt_drop_write(oldnd
.path
.mnt
);
2721 unlock_rename(new_dir
, old_dir
);
2723 path_put(&newnd
.path
);
2726 path_put(&oldnd
.path
);
2732 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
2734 return sys_renameat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
);
2737 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
, const char *link
)
2741 len
= PTR_ERR(link
);
2746 if (len
> (unsigned) buflen
)
2748 if (copy_to_user(buffer
, link
, len
))
2755 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2756 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2757 * using) it for any given inode is up to filesystem.
2759 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2761 struct nameidata nd
;
2766 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
2768 return PTR_ERR(cookie
);
2770 res
= vfs_readlink(dentry
, buffer
, buflen
, nd_get_link(&nd
));
2771 if (dentry
->d_inode
->i_op
->put_link
)
2772 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
2776 int vfs_follow_link(struct nameidata
*nd
, const char *link
)
2778 return __vfs_follow_link(nd
, link
);
2781 /* get the link contents into pagecache */
2782 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
2786 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
2787 page
= read_mapping_page(mapping
, 0, NULL
);
2792 nd_terminate_link(kaddr
, dentry
->d_inode
->i_size
, PAGE_SIZE
- 1);
2796 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2798 struct page
*page
= NULL
;
2799 char *s
= page_getlink(dentry
, &page
);
2800 int res
= vfs_readlink(dentry
,buffer
,buflen
,s
);
2803 page_cache_release(page
);
2808 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
2810 struct page
*page
= NULL
;
2811 nd_set_link(nd
, page_getlink(dentry
, &page
));
2815 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2817 struct page
*page
= cookie
;
2821 page_cache_release(page
);
2826 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
2828 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
2830 struct address_space
*mapping
= inode
->i_mapping
;
2835 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
2837 flags
|= AOP_FLAG_NOFS
;
2840 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
2841 flags
, &page
, &fsdata
);
2845 kaddr
= kmap_atomic(page
, KM_USER0
);
2846 memcpy(kaddr
, symname
, len
-1);
2847 kunmap_atomic(kaddr
, KM_USER0
);
2849 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
2856 mark_inode_dirty(inode
);
2862 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
2864 return __page_symlink(inode
, symname
, len
,
2865 !(mapping_gfp_mask(inode
->i_mapping
) & __GFP_FS
));
2868 const struct inode_operations page_symlink_inode_operations
= {
2869 .readlink
= generic_readlink
,
2870 .follow_link
= page_follow_link_light
,
2871 .put_link
= page_put_link
,
2874 EXPORT_SYMBOL(user_path_at
);
2875 EXPORT_SYMBOL(follow_down
);
2876 EXPORT_SYMBOL(follow_up
);
2877 EXPORT_SYMBOL(get_write_access
); /* binfmt_aout */
2878 EXPORT_SYMBOL(getname
);
2879 EXPORT_SYMBOL(lock_rename
);
2880 EXPORT_SYMBOL(lookup_one_len
);
2881 EXPORT_SYMBOL(page_follow_link_light
);
2882 EXPORT_SYMBOL(page_put_link
);
2883 EXPORT_SYMBOL(page_readlink
);
2884 EXPORT_SYMBOL(__page_symlink
);
2885 EXPORT_SYMBOL(page_symlink
);
2886 EXPORT_SYMBOL(page_symlink_inode_operations
);
2887 EXPORT_SYMBOL(path_lookup
);
2888 EXPORT_SYMBOL(kern_path
);
2889 EXPORT_SYMBOL(vfs_path_lookup
);
2890 EXPORT_SYMBOL(inode_permission
);
2891 EXPORT_SYMBOL(file_permission
);
2892 EXPORT_SYMBOL(unlock_rename
);
2893 EXPORT_SYMBOL(vfs_create
);
2894 EXPORT_SYMBOL(vfs_follow_link
);
2895 EXPORT_SYMBOL(vfs_link
);
2896 EXPORT_SYMBOL(vfs_mkdir
);
2897 EXPORT_SYMBOL(vfs_mknod
);
2898 EXPORT_SYMBOL(generic_permission
);
2899 EXPORT_SYMBOL(vfs_readlink
);
2900 EXPORT_SYMBOL(vfs_rename
);
2901 EXPORT_SYMBOL(vfs_rmdir
);
2902 EXPORT_SYMBOL(vfs_symlink
);
2903 EXPORT_SYMBOL(vfs_unlink
);
2904 EXPORT_SYMBOL(dentry_unhash
);
2905 EXPORT_SYMBOL(generic_readlink
);