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/syscalls.h>
28 #include <linux/mount.h>
29 #include <linux/audit.h>
30 #include <linux/capability.h>
31 #include <linux/file.h>
32 #include <linux/fcntl.h>
33 #include <linux/device_cgroup.h>
34 #include <asm/uaccess.h>
36 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
38 /* [Feb-1997 T. Schoebel-Theuer]
39 * Fundamental changes in the pathname lookup mechanisms (namei)
40 * were necessary because of omirr. The reason is that omirr needs
41 * to know the _real_ pathname, not the user-supplied one, in case
42 * of symlinks (and also when transname replacements occur).
44 * The new code replaces the old recursive symlink resolution with
45 * an iterative one (in case of non-nested symlink chains). It does
46 * this with calls to <fs>_follow_link().
47 * As a side effect, dir_namei(), _namei() and follow_link() are now
48 * replaced with a single function lookup_dentry() that can handle all
49 * the special cases of the former code.
51 * With the new dcache, the pathname is stored at each inode, at least as
52 * long as the refcount of the inode is positive. As a side effect, the
53 * size of the dcache depends on the inode cache and thus is dynamic.
55 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
56 * resolution to correspond with current state of the code.
58 * Note that the symlink resolution is not *completely* iterative.
59 * There is still a significant amount of tail- and mid- recursion in
60 * the algorithm. Also, note that <fs>_readlink() is not used in
61 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
62 * may return different results than <fs>_follow_link(). Many virtual
63 * filesystems (including /proc) exhibit this behavior.
66 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
67 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
68 * and the name already exists in form of a symlink, try to create the new
69 * name indicated by the symlink. The old code always complained that the
70 * name already exists, due to not following the symlink even if its target
71 * is nonexistent. The new semantics affects also mknod() and link() when
72 * the name is a symlink pointing to a non-existant name.
74 * I don't know which semantics is the right one, since I have no access
75 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
76 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
77 * "old" one. Personally, I think the new semantics is much more logical.
78 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
79 * file does succeed in both HP-UX and SunOs, but not in Solaris
80 * and in the old Linux semantics.
83 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
84 * semantics. See the comments in "open_namei" and "do_link" below.
86 * [10-Sep-98 Alan Modra] Another symlink change.
89 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
90 * inside the path - always follow.
91 * in the last component in creation/removal/renaming - never follow.
92 * if LOOKUP_FOLLOW passed - follow.
93 * if the pathname has trailing slashes - follow.
94 * otherwise - don't follow.
95 * (applied in that order).
97 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
98 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
99 * During the 2.4 we need to fix the userland stuff depending on it -
100 * hopefully we will be able to get rid of that wart in 2.5. So far only
101 * XEmacs seems to be relying on it...
104 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
105 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
106 * any extra contention...
109 static int __link_path_walk(const char *name
, struct nameidata
*nd
);
111 /* In order to reduce some races, while at the same time doing additional
112 * checking and hopefully speeding things up, we copy filenames to the
113 * kernel data space before using them..
115 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
116 * PATH_MAX includes the nul terminator --RR.
118 static int do_getname(const char __user
*filename
, char *page
)
121 unsigned long len
= PATH_MAX
;
123 if (!segment_eq(get_fs(), KERNEL_DS
)) {
124 if ((unsigned long) filename
>= TASK_SIZE
)
126 if (TASK_SIZE
- (unsigned long) filename
< PATH_MAX
)
127 len
= TASK_SIZE
- (unsigned long) filename
;
130 retval
= strncpy_from_user(page
, filename
, len
);
134 return -ENAMETOOLONG
;
140 char * getname(const char __user
* filename
)
144 result
= ERR_PTR(-ENOMEM
);
147 int retval
= do_getname(filename
, tmp
);
152 result
= ERR_PTR(retval
);
155 audit_getname(result
);
159 #ifdef CONFIG_AUDITSYSCALL
160 void putname(const char *name
)
162 if (unlikely(!audit_dummy_context()))
167 EXPORT_SYMBOL(putname
);
172 * generic_permission - check for access rights on a Posix-like filesystem
173 * @inode: inode to check access rights for
174 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
175 * @check_acl: optional callback to check for Posix ACLs
177 * Used to check for read/write/execute permissions on a file.
178 * We use "fsuid" for this, letting us set arbitrary permissions
179 * for filesystem access without changing the "normal" uids which
180 * are used for other things..
182 int generic_permission(struct inode
*inode
, int mask
,
183 int (*check_acl
)(struct inode
*inode
, int mask
))
185 umode_t mode
= inode
->i_mode
;
187 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
189 if (current
->fsuid
== inode
->i_uid
)
192 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
) && check_acl
) {
193 int error
= check_acl(inode
, mask
);
194 if (error
== -EACCES
)
195 goto check_capabilities
;
196 else if (error
!= -EAGAIN
)
200 if (in_group_p(inode
->i_gid
))
205 * If the DACs are ok we don't need any capability check.
207 if ((mask
& ~mode
) == 0)
212 * Read/write DACs are always overridable.
213 * Executable DACs are overridable if at least one exec bit is set.
215 if (!(mask
& MAY_EXEC
) ||
216 (inode
->i_mode
& S_IXUGO
) || S_ISDIR(inode
->i_mode
))
217 if (capable(CAP_DAC_OVERRIDE
))
221 * Searching includes executable on directories, else just read.
223 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
224 if (mask
== MAY_READ
|| (S_ISDIR(inode
->i_mode
) && !(mask
& MAY_WRITE
)))
225 if (capable(CAP_DAC_READ_SEARCH
))
231 int inode_permission(struct inode
*inode
, int mask
)
235 if (mask
& MAY_WRITE
) {
236 umode_t mode
= inode
->i_mode
;
239 * Nobody gets write access to a read-only fs.
241 if (IS_RDONLY(inode
) &&
242 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
246 * Nobody gets write access to an immutable file.
248 if (IS_IMMUTABLE(inode
))
252 /* Ordinary permission routines do not understand MAY_APPEND. */
253 if (inode
->i_op
&& inode
->i_op
->permission
) {
254 retval
= inode
->i_op
->permission(inode
, mask
);
257 * Exec permission on a regular file is denied if none
258 * of the execute bits are set.
260 * This check should be done by the ->permission()
263 if ((mask
& MAY_EXEC
) && S_ISREG(inode
->i_mode
) &&
264 !(inode
->i_mode
& S_IXUGO
))
268 retval
= generic_permission(inode
, mask
, NULL
);
273 retval
= devcgroup_inode_permission(inode
, mask
);
277 return security_inode_permission(inode
,
278 mask
& (MAY_READ
|MAY_WRITE
|MAY_EXEC
|MAY_APPEND
));
282 * vfs_permission - check for access rights to a given path
283 * @nd: lookup result that describes the path
284 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
286 * Used to check for read/write/execute permissions on a path.
287 * We use "fsuid" for this, letting us set arbitrary permissions
288 * for filesystem access without changing the "normal" uids which
289 * are used for other things.
291 int vfs_permission(struct nameidata
*nd
, int mask
)
293 return inode_permission(nd
->path
.dentry
->d_inode
, mask
);
297 * file_permission - check for additional access rights to a given file
298 * @file: file to check access rights for
299 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
301 * Used to check for read/write/execute permissions on an already opened
305 * Do not use this function in new code. All access checks should
306 * be done using vfs_permission().
308 int file_permission(struct file
*file
, int mask
)
310 return inode_permission(file
->f_path
.dentry
->d_inode
, mask
);
314 * get_write_access() gets write permission for a file.
315 * put_write_access() releases this write permission.
316 * This is used for regular files.
317 * We cannot support write (and maybe mmap read-write shared) accesses and
318 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
319 * can have the following values:
320 * 0: no writers, no VM_DENYWRITE mappings
321 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
322 * > 0: (i_writecount) users are writing to the file.
324 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
325 * except for the cases where we don't hold i_writecount yet. Then we need to
326 * use {get,deny}_write_access() - these functions check the sign and refuse
327 * to do the change if sign is wrong. Exclusion between them is provided by
328 * the inode->i_lock spinlock.
331 int get_write_access(struct inode
* inode
)
333 spin_lock(&inode
->i_lock
);
334 if (atomic_read(&inode
->i_writecount
) < 0) {
335 spin_unlock(&inode
->i_lock
);
338 atomic_inc(&inode
->i_writecount
);
339 spin_unlock(&inode
->i_lock
);
344 int deny_write_access(struct file
* file
)
346 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
348 spin_lock(&inode
->i_lock
);
349 if (atomic_read(&inode
->i_writecount
) > 0) {
350 spin_unlock(&inode
->i_lock
);
353 atomic_dec(&inode
->i_writecount
);
354 spin_unlock(&inode
->i_lock
);
360 * path_get - get a reference to a path
361 * @path: path to get the reference to
363 * Given a path increment the reference count to the dentry and the vfsmount.
365 void path_get(struct path
*path
)
370 EXPORT_SYMBOL(path_get
);
373 * path_put - put a reference to a path
374 * @path: path to put the reference to
376 * Given a path decrement the reference count to the dentry and the vfsmount.
378 void path_put(struct path
*path
)
383 EXPORT_SYMBOL(path_put
);
386 * release_open_intent - free up open intent resources
387 * @nd: pointer to nameidata
389 void release_open_intent(struct nameidata
*nd
)
391 if (nd
->intent
.open
.file
->f_path
.dentry
== NULL
)
392 put_filp(nd
->intent
.open
.file
);
394 fput(nd
->intent
.open
.file
);
397 static inline struct dentry
*
398 do_revalidate(struct dentry
*dentry
, struct nameidata
*nd
)
400 int status
= dentry
->d_op
->d_revalidate(dentry
, nd
);
401 if (unlikely(status
<= 0)) {
403 * The dentry failed validation.
404 * If d_revalidate returned 0 attempt to invalidate
405 * the dentry otherwise d_revalidate is asking us
406 * to return a fail status.
409 if (!d_invalidate(dentry
)) {
415 dentry
= ERR_PTR(status
);
422 * Internal lookup() using the new generic dcache.
425 static struct dentry
* cached_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
427 struct dentry
* dentry
= __d_lookup(parent
, name
);
429 /* lockess __d_lookup may fail due to concurrent d_move()
430 * in some unrelated directory, so try with d_lookup
433 dentry
= d_lookup(parent
, name
);
435 if (dentry
&& dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
436 dentry
= do_revalidate(dentry
, nd
);
442 * Short-cut version of permission(), for calling by
443 * path_walk(), when dcache lock is held. Combines parts
444 * of permission() and generic_permission(), and tests ONLY for
445 * MAY_EXEC permission.
447 * If appropriate, check DAC only. If not appropriate, or
448 * short-cut DAC fails, then call permission() to do more
449 * complete permission check.
451 static int exec_permission_lite(struct inode
*inode
)
453 umode_t mode
= inode
->i_mode
;
455 if (inode
->i_op
&& inode
->i_op
->permission
)
458 if (current
->fsuid
== inode
->i_uid
)
460 else if (in_group_p(inode
->i_gid
))
466 if ((inode
->i_mode
& S_IXUGO
) && capable(CAP_DAC_OVERRIDE
))
469 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_OVERRIDE
))
472 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_READ_SEARCH
))
477 return security_inode_permission(inode
, MAY_EXEC
);
481 * This is called when everything else fails, and we actually have
482 * to go to the low-level filesystem to find out what we should do..
484 * We get the directory semaphore, and after getting that we also
485 * make sure that nobody added the entry to the dcache in the meantime..
488 static struct dentry
* real_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
490 struct dentry
* result
;
491 struct inode
*dir
= parent
->d_inode
;
493 mutex_lock(&dir
->i_mutex
);
495 * First re-do the cached lookup just in case it was created
496 * while we waited for the directory semaphore..
498 * FIXME! This could use version numbering or similar to
499 * avoid unnecessary cache lookups.
501 * The "dcache_lock" is purely to protect the RCU list walker
502 * from concurrent renames at this point (we mustn't get false
503 * negatives from the RCU list walk here, unlike the optimistic
506 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
508 result
= d_lookup(parent
, name
);
510 struct dentry
*dentry
;
512 /* Don't create child dentry for a dead directory. */
513 result
= ERR_PTR(-ENOENT
);
517 dentry
= d_alloc(parent
, name
);
518 result
= ERR_PTR(-ENOMEM
);
520 result
= dir
->i_op
->lookup(dir
, dentry
, nd
);
527 mutex_unlock(&dir
->i_mutex
);
532 * Uhhuh! Nasty case: the cache was re-populated while
533 * we waited on the semaphore. Need to revalidate.
535 mutex_unlock(&dir
->i_mutex
);
536 if (result
->d_op
&& result
->d_op
->d_revalidate
) {
537 result
= do_revalidate(result
, nd
);
539 result
= ERR_PTR(-ENOENT
);
545 static __always_inline
void
546 walk_init_root(const char *name
, struct nameidata
*nd
)
548 struct fs_struct
*fs
= current
->fs
;
550 read_lock(&fs
->lock
);
553 read_unlock(&fs
->lock
);
557 * Wrapper to retry pathname resolution whenever the underlying
558 * file system returns an ESTALE.
560 * Retry the whole path once, forcing real lookup requests
561 * instead of relying on the dcache.
563 static __always_inline
int link_path_walk(const char *name
, struct nameidata
*nd
)
565 struct path save
= nd
->path
;
568 /* make sure the stuff we saved doesn't go away */
571 result
= __link_path_walk(name
, nd
);
572 if (result
== -ESTALE
) {
573 /* nd->path had been dropped */
576 nd
->flags
|= LOOKUP_REVAL
;
577 result
= __link_path_walk(name
, nd
);
585 static __always_inline
int __vfs_follow_link(struct nameidata
*nd
, const char *link
)
594 walk_init_root(link
, nd
);
596 res
= link_path_walk(link
, nd
);
597 if (nd
->depth
|| res
|| nd
->last_type
!=LAST_NORM
)
600 * If it is an iterative symlinks resolution in open_namei() we
601 * have to copy the last component. And all that crap because of
602 * bloody create() on broken symlinks. Furrfu...
605 if (unlikely(!name
)) {
609 strcpy(name
, nd
->last
.name
);
610 nd
->last
.name
= name
;
614 return PTR_ERR(link
);
617 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
620 if (path
->mnt
!= nd
->path
.mnt
)
624 static inline void path_to_nameidata(struct path
*path
, struct nameidata
*nd
)
626 dput(nd
->path
.dentry
);
627 if (nd
->path
.mnt
!= path
->mnt
)
628 mntput(nd
->path
.mnt
);
629 nd
->path
.mnt
= path
->mnt
;
630 nd
->path
.dentry
= path
->dentry
;
633 static __always_inline
int __do_follow_link(struct path
*path
, struct nameidata
*nd
)
637 struct dentry
*dentry
= path
->dentry
;
639 touch_atime(path
->mnt
, dentry
);
640 nd_set_link(nd
, NULL
);
642 if (path
->mnt
!= nd
->path
.mnt
) {
643 path_to_nameidata(path
, nd
);
647 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
648 error
= PTR_ERR(cookie
);
649 if (!IS_ERR(cookie
)) {
650 char *s
= nd_get_link(nd
);
653 error
= __vfs_follow_link(nd
, s
);
654 if (dentry
->d_inode
->i_op
->put_link
)
655 dentry
->d_inode
->i_op
->put_link(dentry
, nd
, cookie
);
663 * This limits recursive symlink follows to 8, while
664 * limiting consecutive symlinks to 40.
666 * Without that kind of total limit, nasty chains of consecutive
667 * symlinks can cause almost arbitrarily long lookups.
669 static inline int do_follow_link(struct path
*path
, struct nameidata
*nd
)
672 if (current
->link_count
>= MAX_NESTED_LINKS
)
674 if (current
->total_link_count
>= 40)
676 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
678 err
= security_inode_follow_link(path
->dentry
, nd
);
681 current
->link_count
++;
682 current
->total_link_count
++;
684 err
= __do_follow_link(path
, nd
);
685 current
->link_count
--;
689 path_put_conditional(path
, nd
);
694 int follow_up(struct vfsmount
**mnt
, struct dentry
**dentry
)
696 struct vfsmount
*parent
;
697 struct dentry
*mountpoint
;
698 spin_lock(&vfsmount_lock
);
699 parent
=(*mnt
)->mnt_parent
;
700 if (parent
== *mnt
) {
701 spin_unlock(&vfsmount_lock
);
705 mountpoint
=dget((*mnt
)->mnt_mountpoint
);
706 spin_unlock(&vfsmount_lock
);
708 *dentry
= mountpoint
;
714 /* no need for dcache_lock, as serialization is taken care in
717 static int __follow_mount(struct path
*path
)
720 while (d_mountpoint(path
->dentry
)) {
721 struct vfsmount
*mounted
= lookup_mnt(path
->mnt
, path
->dentry
);
728 path
->dentry
= dget(mounted
->mnt_root
);
734 static void follow_mount(struct vfsmount
**mnt
, struct dentry
**dentry
)
736 while (d_mountpoint(*dentry
)) {
737 struct vfsmount
*mounted
= lookup_mnt(*mnt
, *dentry
);
743 *dentry
= dget(mounted
->mnt_root
);
747 /* no need for dcache_lock, as serialization is taken care in
750 int follow_down(struct vfsmount
**mnt
, struct dentry
**dentry
)
752 struct vfsmount
*mounted
;
754 mounted
= lookup_mnt(*mnt
, *dentry
);
759 *dentry
= dget(mounted
->mnt_root
);
765 static __always_inline
void follow_dotdot(struct nameidata
*nd
)
767 struct fs_struct
*fs
= current
->fs
;
770 struct vfsmount
*parent
;
771 struct dentry
*old
= nd
->path
.dentry
;
773 read_lock(&fs
->lock
);
774 if (nd
->path
.dentry
== fs
->root
.dentry
&&
775 nd
->path
.mnt
== fs
->root
.mnt
) {
776 read_unlock(&fs
->lock
);
779 read_unlock(&fs
->lock
);
780 spin_lock(&dcache_lock
);
781 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
782 nd
->path
.dentry
= dget(nd
->path
.dentry
->d_parent
);
783 spin_unlock(&dcache_lock
);
787 spin_unlock(&dcache_lock
);
788 spin_lock(&vfsmount_lock
);
789 parent
= nd
->path
.mnt
->mnt_parent
;
790 if (parent
== nd
->path
.mnt
) {
791 spin_unlock(&vfsmount_lock
);
795 nd
->path
.dentry
= dget(nd
->path
.mnt
->mnt_mountpoint
);
796 spin_unlock(&vfsmount_lock
);
798 mntput(nd
->path
.mnt
);
799 nd
->path
.mnt
= parent
;
801 follow_mount(&nd
->path
.mnt
, &nd
->path
.dentry
);
805 * It's more convoluted than I'd like it to be, but... it's still fairly
806 * small and for now I'd prefer to have fast path as straight as possible.
807 * It _is_ time-critical.
809 static int do_lookup(struct nameidata
*nd
, struct qstr
*name
,
812 struct vfsmount
*mnt
= nd
->path
.mnt
;
813 struct dentry
*dentry
= __d_lookup(nd
->path
.dentry
, name
);
817 if (dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
818 goto need_revalidate
;
821 path
->dentry
= dentry
;
822 __follow_mount(path
);
826 dentry
= real_lookup(nd
->path
.dentry
, name
, nd
);
832 dentry
= do_revalidate(dentry
, nd
);
840 return PTR_ERR(dentry
);
844 * This is a temporary kludge to deal with "automount" symlinks; proper
845 * solution is to trigger them on follow_mount(), so that do_lookup()
846 * would DTRT. To be killed before 2.6.34-final.
848 static inline int follow_on_final(struct inode
*inode
, unsigned lookup_flags
)
850 return inode
&& unlikely(inode
->i_op
->follow_link
) &&
851 ((lookup_flags
& LOOKUP_FOLLOW
) || S_ISDIR(inode
->i_mode
));
856 * This is the basic name resolution function, turning a pathname into
857 * the final dentry. We expect 'base' to be positive and a directory.
859 * Returns 0 and nd will have valid dentry and mnt on success.
860 * Returns error and drops reference to input namei data on failure.
862 static int __link_path_walk(const char *name
, struct nameidata
*nd
)
867 unsigned int lookup_flags
= nd
->flags
;
874 inode
= nd
->path
.dentry
->d_inode
;
876 lookup_flags
= LOOKUP_FOLLOW
| (nd
->flags
& LOOKUP_CONTINUE
);
878 /* At this point we know we have a real path component. */
884 nd
->flags
|= LOOKUP_CONTINUE
;
885 err
= exec_permission_lite(inode
);
887 err
= vfs_permission(nd
, MAY_EXEC
);
892 c
= *(const unsigned char *)name
;
894 hash
= init_name_hash();
897 hash
= partial_name_hash(c
, hash
);
898 c
= *(const unsigned char *)name
;
899 } while (c
&& (c
!= '/'));
900 this.len
= name
- (const char *) this.name
;
901 this.hash
= end_name_hash(hash
);
903 /* remove trailing slashes? */
906 while (*++name
== '/');
908 goto last_with_slashes
;
911 * "." and ".." are special - ".." especially so because it has
912 * to be able to know about the current root directory and
913 * parent relationships.
915 if (this.name
[0] == '.') switch (this.len
) {
919 if (this.name
[1] != '.')
922 inode
= nd
->path
.dentry
->d_inode
;
928 * See if the low-level filesystem might want
929 * to use its own hash..
931 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
932 err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
937 /* This does the actual lookups.. */
938 err
= do_lookup(nd
, &this, &next
);
943 inode
= next
.dentry
->d_inode
;
950 if (inode
->i_op
->follow_link
) {
951 err
= do_follow_link(&next
, nd
);
955 inode
= nd
->path
.dentry
->d_inode
;
962 path_to_nameidata(&next
, nd
);
964 if (!inode
->i_op
->lookup
)
967 /* here ends the main loop */
970 lookup_flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
972 /* Clear LOOKUP_CONTINUE iff it was previously unset */
973 nd
->flags
&= lookup_flags
| ~LOOKUP_CONTINUE
;
974 if (lookup_flags
& LOOKUP_PARENT
)
976 if (this.name
[0] == '.') switch (this.len
) {
980 if (this.name
[1] != '.')
983 inode
= nd
->path
.dentry
->d_inode
;
988 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
989 err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
994 err
= do_lookup(nd
, &this, &next
);
997 inode
= next
.dentry
->d_inode
;
998 if (follow_on_final(inode
, lookup_flags
)) {
999 err
= do_follow_link(&next
, nd
);
1002 inode
= nd
->path
.dentry
->d_inode
;
1004 path_to_nameidata(&next
, nd
);
1008 if (lookup_flags
& LOOKUP_DIRECTORY
) {
1010 if (!inode
->i_op
|| !inode
->i_op
->lookup
)
1016 nd
->last_type
= LAST_NORM
;
1017 if (this.name
[0] != '.')
1020 nd
->last_type
= LAST_DOT
;
1021 else if (this.len
== 2 && this.name
[1] == '.')
1022 nd
->last_type
= LAST_DOTDOT
;
1027 * We bypassed the ordinary revalidation routines.
1028 * We may need to check the cached dentry for staleness.
1030 if (nd
->path
.dentry
&& nd
->path
.dentry
->d_sb
&&
1031 (nd
->path
.dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
)) {
1033 /* Note: we do not d_invalidate() */
1034 if (!nd
->path
.dentry
->d_op
->d_revalidate(
1035 nd
->path
.dentry
, nd
))
1041 path_put_conditional(&next
, nd
);
1044 path_put(&nd
->path
);
1049 static int path_walk(const char *name
, struct nameidata
*nd
)
1051 current
->total_link_count
= 0;
1052 return link_path_walk(name
, nd
);
1055 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1056 static int do_path_lookup(int dfd
, const char *name
,
1057 unsigned int flags
, struct nameidata
*nd
)
1062 struct fs_struct
*fs
= current
->fs
;
1064 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1069 read_lock(&fs
->lock
);
1070 nd
->path
= fs
->root
;
1071 path_get(&fs
->root
);
1072 read_unlock(&fs
->lock
);
1073 } else if (dfd
== AT_FDCWD
) {
1074 read_lock(&fs
->lock
);
1077 read_unlock(&fs
->lock
);
1079 struct dentry
*dentry
;
1081 file
= fget_light(dfd
, &fput_needed
);
1086 dentry
= file
->f_path
.dentry
;
1089 if (!S_ISDIR(dentry
->d_inode
->i_mode
))
1092 retval
= file_permission(file
, MAY_EXEC
);
1096 nd
->path
= file
->f_path
;
1097 path_get(&file
->f_path
);
1099 fput_light(file
, fput_needed
);
1102 retval
= path_walk(name
, nd
);
1103 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1104 nd
->path
.dentry
->d_inode
))
1105 audit_inode(name
, nd
->path
.dentry
);
1110 fput_light(file
, fput_needed
);
1114 int path_lookup(const char *name
, unsigned int flags
,
1115 struct nameidata
*nd
)
1117 return do_path_lookup(AT_FDCWD
, name
, flags
, nd
);
1121 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1122 * @dentry: pointer to dentry of the base directory
1123 * @mnt: pointer to vfs mount of the base directory
1124 * @name: pointer to file name
1125 * @flags: lookup flags
1126 * @nd: pointer to nameidata
1128 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
1129 const char *name
, unsigned int flags
,
1130 struct nameidata
*nd
)
1134 /* same as do_path_lookup */
1135 nd
->last_type
= LAST_ROOT
;
1139 nd
->path
.dentry
= dentry
;
1141 path_get(&nd
->path
);
1143 retval
= path_walk(name
, nd
);
1144 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1145 nd
->path
.dentry
->d_inode
))
1146 audit_inode(name
, nd
->path
.dentry
);
1152 static int __path_lookup_intent_open(int dfd
, const char *name
,
1153 unsigned int lookup_flags
, struct nameidata
*nd
,
1154 int open_flags
, int create_mode
)
1156 struct file
*filp
= get_empty_filp();
1161 nd
->intent
.open
.file
= filp
;
1162 nd
->intent
.open
.flags
= open_flags
;
1163 nd
->intent
.open
.create_mode
= create_mode
;
1164 err
= do_path_lookup(dfd
, name
, lookup_flags
|LOOKUP_OPEN
, nd
);
1165 if (IS_ERR(nd
->intent
.open
.file
)) {
1167 err
= PTR_ERR(nd
->intent
.open
.file
);
1168 path_put(&nd
->path
);
1170 } else if (err
!= 0)
1171 release_open_intent(nd
);
1176 * path_lookup_open - lookup a file path with open intent
1177 * @dfd: the directory to use as base, or AT_FDCWD
1178 * @name: pointer to file name
1179 * @lookup_flags: lookup intent flags
1180 * @nd: pointer to nameidata
1181 * @open_flags: open intent flags
1183 int path_lookup_open(int dfd
, const char *name
, unsigned int lookup_flags
,
1184 struct nameidata
*nd
, int open_flags
)
1186 return __path_lookup_intent_open(dfd
, name
, lookup_flags
, nd
,
1191 * path_lookup_create - lookup a file path with open + create intent
1192 * @dfd: the directory to use as base, or AT_FDCWD
1193 * @name: pointer to file name
1194 * @lookup_flags: lookup intent flags
1195 * @nd: pointer to nameidata
1196 * @open_flags: open intent flags
1197 * @create_mode: create intent flags
1199 static int path_lookup_create(int dfd
, const char *name
,
1200 unsigned int lookup_flags
, struct nameidata
*nd
,
1201 int open_flags
, int create_mode
)
1203 return __path_lookup_intent_open(dfd
, name
, lookup_flags
|LOOKUP_CREATE
,
1204 nd
, open_flags
, create_mode
);
1207 static struct dentry
*__lookup_hash(struct qstr
*name
,
1208 struct dentry
*base
, struct nameidata
*nd
)
1210 struct dentry
*dentry
;
1211 struct inode
*inode
;
1214 inode
= base
->d_inode
;
1217 * See if the low-level filesystem might want
1218 * to use its own hash..
1220 if (base
->d_op
&& base
->d_op
->d_hash
) {
1221 err
= base
->d_op
->d_hash(base
, name
);
1222 dentry
= ERR_PTR(err
);
1227 dentry
= cached_lookup(base
, name
, nd
);
1231 /* Don't create child dentry for a dead directory. */
1232 dentry
= ERR_PTR(-ENOENT
);
1233 if (IS_DEADDIR(inode
))
1236 new = d_alloc(base
, name
);
1237 dentry
= ERR_PTR(-ENOMEM
);
1240 dentry
= inode
->i_op
->lookup(inode
, new, nd
);
1251 * Restricted form of lookup. Doesn't follow links, single-component only,
1252 * needs parent already locked. Doesn't follow mounts.
1255 static struct dentry
*lookup_hash(struct nameidata
*nd
)
1259 err
= inode_permission(nd
->path
.dentry
->d_inode
, MAY_EXEC
);
1261 return ERR_PTR(err
);
1262 return __lookup_hash(&nd
->last
, nd
->path
.dentry
, nd
);
1265 static int __lookup_one_len(const char *name
, struct qstr
*this,
1266 struct dentry
*base
, int len
)
1276 hash
= init_name_hash();
1278 c
= *(const unsigned char *)name
++;
1279 if (c
== '/' || c
== '\0')
1281 hash
= partial_name_hash(c
, hash
);
1283 this->hash
= end_name_hash(hash
);
1288 * lookup_one_len - filesystem helper to lookup single pathname component
1289 * @name: pathname component to lookup
1290 * @base: base directory to lookup from
1291 * @len: maximum length @len should be interpreted to
1293 * Note that this routine is purely a helper for filesystem usage and should
1294 * not be called by generic code. Also note that by using this function the
1295 * nameidata argument is passed to the filesystem methods and a filesystem
1296 * using this helper needs to be prepared for that.
1298 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
1303 err
= __lookup_one_len(name
, &this, base
, len
);
1305 return ERR_PTR(err
);
1307 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
1309 return ERR_PTR(err
);
1310 return __lookup_hash(&this, base
, NULL
);
1314 * lookup_one_noperm - bad hack for sysfs
1315 * @name: pathname component to lookup
1316 * @base: base directory to lookup from
1318 * This is a variant of lookup_one_len that doesn't perform any permission
1319 * checks. It's a horrible hack to work around the braindead sysfs
1320 * architecture and should not be used anywhere else.
1322 * DON'T USE THIS FUNCTION EVER, thanks.
1324 struct dentry
*lookup_one_noperm(const char *name
, struct dentry
*base
)
1329 err
= __lookup_one_len(name
, &this, base
, strlen(name
));
1331 return ERR_PTR(err
);
1332 return __lookup_hash(&this, base
, NULL
);
1335 int user_path_at(int dfd
, const char __user
*name
, unsigned flags
,
1338 struct nameidata nd
;
1339 char *tmp
= getname(name
);
1340 int err
= PTR_ERR(tmp
);
1343 BUG_ON(flags
& LOOKUP_PARENT
);
1345 err
= do_path_lookup(dfd
, tmp
, flags
, &nd
);
1353 static int user_path_parent(int dfd
, const char __user
*path
,
1354 struct nameidata
*nd
, char **name
)
1356 char *s
= getname(path
);
1362 error
= do_path_lookup(dfd
, s
, LOOKUP_PARENT
, nd
);
1372 * It's inline, so penalty for filesystems that don't use sticky bit is
1375 static inline int check_sticky(struct inode
*dir
, struct inode
*inode
)
1377 if (!(dir
->i_mode
& S_ISVTX
))
1379 if (inode
->i_uid
== current
->fsuid
)
1381 if (dir
->i_uid
== current
->fsuid
)
1383 return !capable(CAP_FOWNER
);
1387 * Check whether we can remove a link victim from directory dir, check
1388 * whether the type of victim is right.
1389 * 1. We can't do it if dir is read-only (done in permission())
1390 * 2. We should have write and exec permissions on dir
1391 * 3. We can't remove anything from append-only dir
1392 * 4. We can't do anything with immutable dir (done in permission())
1393 * 5. If the sticky bit on dir is set we should either
1394 * a. be owner of dir, or
1395 * b. be owner of victim, or
1396 * c. have CAP_FOWNER capability
1397 * 6. If the victim is append-only or immutable we can't do antyhing with
1398 * links pointing to it.
1399 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1400 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1401 * 9. We can't remove a root or mountpoint.
1402 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1403 * nfs_async_unlink().
1405 static int may_delete(struct inode
*dir
,struct dentry
*victim
,int isdir
)
1409 if (!victim
->d_inode
)
1412 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
1413 audit_inode_child(victim
->d_name
.name
, victim
, dir
);
1415 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
1420 if (check_sticky(dir
, victim
->d_inode
)||IS_APPEND(victim
->d_inode
)||
1421 IS_IMMUTABLE(victim
->d_inode
))
1424 if (!S_ISDIR(victim
->d_inode
->i_mode
))
1426 if (IS_ROOT(victim
))
1428 } else if (S_ISDIR(victim
->d_inode
->i_mode
))
1430 if (IS_DEADDIR(dir
))
1432 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
1437 /* Check whether we can create an object with dentry child in directory
1439 * 1. We can't do it if child already exists (open has special treatment for
1440 * this case, but since we are inlined it's OK)
1441 * 2. We can't do it if dir is read-only (done in permission())
1442 * 3. We should have write and exec permissions on dir
1443 * 4. We can't do it if dir is immutable (done in permission())
1445 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
1449 if (IS_DEADDIR(dir
))
1451 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
1455 * O_DIRECTORY translates into forcing a directory lookup.
1457 static inline int lookup_flags(unsigned int f
)
1459 unsigned long retval
= LOOKUP_FOLLOW
;
1462 retval
&= ~LOOKUP_FOLLOW
;
1464 if (f
& O_DIRECTORY
)
1465 retval
|= LOOKUP_DIRECTORY
;
1471 * p1 and p2 should be directories on the same fs.
1473 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
1478 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1482 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1484 for (p
= p1
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1485 if (p
->d_parent
== p2
) {
1486 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1487 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1492 for (p
= p2
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1493 if (p
->d_parent
== p1
) {
1494 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1495 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1500 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1501 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1505 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
1507 mutex_unlock(&p1
->d_inode
->i_mutex
);
1509 mutex_unlock(&p2
->d_inode
->i_mutex
);
1510 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1514 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1515 struct nameidata
*nd
)
1517 int error
= may_create(dir
, dentry
);
1522 if (!dir
->i_op
|| !dir
->i_op
->create
)
1523 return -EACCES
; /* shouldn't it be ENOSYS? */
1526 error
= security_inode_create(dir
, dentry
, mode
);
1530 error
= dir
->i_op
->create(dir
, dentry
, mode
, nd
);
1532 fsnotify_create(dir
, dentry
);
1536 int may_open(struct nameidata
*nd
, int acc_mode
, int flag
)
1538 struct dentry
*dentry
= nd
->path
.dentry
;
1539 struct inode
*inode
= dentry
->d_inode
;
1545 if (S_ISLNK(inode
->i_mode
))
1548 if (S_ISDIR(inode
->i_mode
) && (acc_mode
& MAY_WRITE
))
1552 * FIFO's, sockets and device files are special: they don't
1553 * actually live on the filesystem itself, and as such you
1554 * can write to them even if the filesystem is read-only.
1556 if (S_ISFIFO(inode
->i_mode
) || S_ISSOCK(inode
->i_mode
)) {
1558 } else if (S_ISBLK(inode
->i_mode
) || S_ISCHR(inode
->i_mode
)) {
1559 if (nd
->path
.mnt
->mnt_flags
& MNT_NODEV
)
1565 error
= vfs_permission(nd
, acc_mode
);
1569 * An append-only file must be opened in append mode for writing.
1571 if (IS_APPEND(inode
)) {
1572 if ((flag
& FMODE_WRITE
) && !(flag
& O_APPEND
))
1578 /* O_NOATIME can only be set by the owner or superuser */
1579 if (flag
& O_NOATIME
)
1580 if (!is_owner_or_cap(inode
))
1584 * Ensure there are no outstanding leases on the file.
1586 error
= break_lease(inode
, flag
);
1590 if (flag
& O_TRUNC
) {
1591 error
= get_write_access(inode
);
1596 * Refuse to truncate files with mandatory locks held on them.
1598 error
= locks_verify_locked(inode
);
1602 error
= do_truncate(dentry
, 0,
1603 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
1606 put_write_access(inode
);
1610 if (flag
& FMODE_WRITE
)
1617 * Be careful about ever adding any more callers of this
1618 * function. Its flags must be in the namei format, not
1619 * what get passed to sys_open().
1621 static int __open_namei_create(struct nameidata
*nd
, struct path
*path
,
1625 struct dentry
*dir
= nd
->path
.dentry
;
1627 if (!IS_POSIXACL(dir
->d_inode
))
1628 mode
&= ~current
->fs
->umask
;
1629 error
= vfs_create(dir
->d_inode
, path
->dentry
, mode
, nd
);
1630 mutex_unlock(&dir
->d_inode
->i_mutex
);
1631 dput(nd
->path
.dentry
);
1632 nd
->path
.dentry
= path
->dentry
;
1635 /* Don't check for write permission, don't truncate */
1636 return may_open(nd
, 0, flag
& ~O_TRUNC
);
1640 * Note that while the flag value (low two bits) for sys_open means:
1645 * it is changed into
1646 * 00 - no permissions needed
1647 * 01 - read-permission
1648 * 10 - write-permission
1650 * for the internal routines (ie open_namei()/follow_link() etc)
1651 * This is more logical, and also allows the 00 "no perm needed"
1652 * to be used for symlinks (where the permissions are checked
1656 static inline int open_to_namei_flags(int flag
)
1658 if ((flag
+1) & O_ACCMODE
)
1663 static int open_will_write_to_fs(int flag
, struct inode
*inode
)
1666 * We'll never write to the fs underlying
1669 if (special_file(inode
->i_mode
))
1671 return (flag
& O_TRUNC
);
1675 * Note that the low bits of the passed in "open_flag"
1676 * are not the same as in the local variable "flag". See
1677 * open_to_namei_flags() for more details.
1679 struct file
*do_filp_open(int dfd
, const char *pathname
,
1680 int open_flag
, int mode
)
1683 struct nameidata nd
;
1684 int acc_mode
, error
;
1689 int flag
= open_to_namei_flags(open_flag
);
1691 acc_mode
= MAY_OPEN
| ACC_MODE(flag
);
1693 /* O_TRUNC implies we need access checks for write permissions */
1695 acc_mode
|= MAY_WRITE
;
1697 /* Allow the LSM permission hook to distinguish append
1698 access from general write access. */
1699 if (flag
& O_APPEND
)
1700 acc_mode
|= MAY_APPEND
;
1703 * The simplest case - just a plain lookup.
1705 if (!(flag
& O_CREAT
)) {
1706 error
= path_lookup_open(dfd
, pathname
, lookup_flags(flag
),
1709 return ERR_PTR(error
);
1714 * Create - we need to know the parent.
1716 error
= path_lookup_create(dfd
, pathname
, LOOKUP_PARENT
,
1719 return ERR_PTR(error
);
1722 * We have the parent and last component. First of all, check
1723 * that we are not asked to creat(2) an obvious directory - that
1727 if (nd
.last_type
!= LAST_NORM
|| nd
.last
.name
[nd
.last
.len
])
1730 dir
= nd
.path
.dentry
;
1731 nd
.flags
&= ~LOOKUP_PARENT
;
1732 mutex_lock(&dir
->d_inode
->i_mutex
);
1733 path
.dentry
= lookup_hash(&nd
);
1734 path
.mnt
= nd
.path
.mnt
;
1737 error
= PTR_ERR(path
.dentry
);
1738 if (IS_ERR(path
.dentry
)) {
1739 mutex_unlock(&dir
->d_inode
->i_mutex
);
1743 if (IS_ERR(nd
.intent
.open
.file
)) {
1744 error
= PTR_ERR(nd
.intent
.open
.file
);
1745 goto exit_mutex_unlock
;
1748 /* Negative dentry, just create the file */
1749 if (!path
.dentry
->d_inode
) {
1751 * This write is needed to ensure that a
1752 * ro->rw transition does not occur between
1753 * the time when the file is created and when
1754 * a permanent write count is taken through
1755 * the 'struct file' in nameidata_to_filp().
1757 error
= mnt_want_write(nd
.path
.mnt
);
1759 goto exit_mutex_unlock
;
1760 error
= __open_namei_create(&nd
, &path
, flag
, mode
);
1762 mnt_drop_write(nd
.path
.mnt
);
1765 filp
= nameidata_to_filp(&nd
, open_flag
);
1766 mnt_drop_write(nd
.path
.mnt
);
1771 * It already exists.
1773 mutex_unlock(&dir
->d_inode
->i_mutex
);
1774 audit_inode(pathname
, path
.dentry
);
1780 if (__follow_mount(&path
)) {
1782 if (flag
& O_NOFOLLOW
)
1787 if (!path
.dentry
->d_inode
)
1789 if (path
.dentry
->d_inode
->i_op
&& path
.dentry
->d_inode
->i_op
->follow_link
)
1792 path_to_nameidata(&path
, &nd
);
1794 if (path
.dentry
->d_inode
&& S_ISDIR(path
.dentry
->d_inode
->i_mode
))
1799 * 1. may_open() truncates a file
1800 * 2. a rw->ro mount transition occurs
1801 * 3. nameidata_to_filp() fails due to
1803 * That would be inconsistent, and should
1804 * be avoided. Taking this mnt write here
1805 * ensures that (2) can not occur.
1807 will_write
= open_will_write_to_fs(flag
, nd
.path
.dentry
->d_inode
);
1809 error
= mnt_want_write(nd
.path
.mnt
);
1813 error
= may_open(&nd
, acc_mode
, flag
);
1816 mnt_drop_write(nd
.path
.mnt
);
1819 filp
= nameidata_to_filp(&nd
, open_flag
);
1821 * It is now safe to drop the mnt write
1822 * because the filp has had a write taken
1826 mnt_drop_write(nd
.path
.mnt
);
1830 mutex_unlock(&dir
->d_inode
->i_mutex
);
1832 path_put_conditional(&path
, &nd
);
1834 if (!IS_ERR(nd
.intent
.open
.file
))
1835 release_open_intent(&nd
);
1837 return ERR_PTR(error
);
1841 if (flag
& O_NOFOLLOW
)
1844 * This is subtle. Instead of calling do_follow_link() we do the
1845 * thing by hands. The reason is that this way we have zero link_count
1846 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1847 * After that we have the parent and last component, i.e.
1848 * we are in the same situation as after the first path_walk().
1849 * Well, almost - if the last component is normal we get its copy
1850 * stored in nd->last.name and we will have to putname() it when we
1851 * are done. Procfs-like symlinks just set LAST_BIND.
1853 nd
.flags
|= LOOKUP_PARENT
;
1854 error
= security_inode_follow_link(path
.dentry
, &nd
);
1857 error
= __do_follow_link(&path
, &nd
);
1859 /* Does someone understand code flow here? Or it is only
1860 * me so stupid? Anathema to whoever designed this non-sense
1861 * with "intent.open".
1863 release_open_intent(&nd
);
1864 return ERR_PTR(error
);
1866 nd
.flags
&= ~LOOKUP_PARENT
;
1867 if (nd
.last_type
== LAST_BIND
)
1870 if (nd
.last_type
!= LAST_NORM
)
1872 if (nd
.last
.name
[nd
.last
.len
]) {
1873 __putname(nd
.last
.name
);
1878 __putname(nd
.last
.name
);
1881 dir
= nd
.path
.dentry
;
1882 mutex_lock(&dir
->d_inode
->i_mutex
);
1883 path
.dentry
= lookup_hash(&nd
);
1884 path
.mnt
= nd
.path
.mnt
;
1885 __putname(nd
.last
.name
);
1890 * filp_open - open file and return file pointer
1892 * @filename: path to open
1893 * @flags: open flags as per the open(2) second argument
1894 * @mode: mode for the new file if O_CREAT is set, else ignored
1896 * This is the helper to open a file from kernelspace if you really
1897 * have to. But in generally you should not do this, so please move
1898 * along, nothing to see here..
1900 struct file
*filp_open(const char *filename
, int flags
, int mode
)
1902 return do_filp_open(AT_FDCWD
, filename
, flags
, mode
);
1904 EXPORT_SYMBOL(filp_open
);
1907 * lookup_create - lookup a dentry, creating it if it doesn't exist
1908 * @nd: nameidata info
1909 * @is_dir: directory flag
1911 * Simple function to lookup and return a dentry and create it
1912 * if it doesn't exist. Is SMP-safe.
1914 * Returns with nd->path.dentry->d_inode->i_mutex locked.
1916 struct dentry
*lookup_create(struct nameidata
*nd
, int is_dir
)
1918 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
1920 mutex_lock_nested(&nd
->path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1922 * Yucky last component or no last component at all?
1923 * (foo/., foo/.., /////)
1925 if (nd
->last_type
!= LAST_NORM
)
1927 nd
->flags
&= ~LOOKUP_PARENT
;
1928 nd
->flags
|= LOOKUP_CREATE
;
1929 nd
->intent
.open
.flags
= O_EXCL
;
1932 * Do the final lookup.
1934 dentry
= lookup_hash(nd
);
1938 if (dentry
->d_inode
)
1941 * Special case - lookup gave negative, but... we had foo/bar/
1942 * From the vfs_mknod() POV we just have a negative dentry -
1943 * all is fine. Let's be bastards - you had / on the end, you've
1944 * been asking for (non-existent) directory. -ENOENT for you.
1946 if (unlikely(!is_dir
&& nd
->last
.name
[nd
->last
.len
])) {
1948 dentry
= ERR_PTR(-ENOENT
);
1953 dentry
= ERR_PTR(-EEXIST
);
1957 EXPORT_SYMBOL_GPL(lookup_create
);
1959 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1961 int error
= may_create(dir
, dentry
);
1966 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
1969 if (!dir
->i_op
|| !dir
->i_op
->mknod
)
1972 error
= devcgroup_inode_mknod(mode
, dev
);
1976 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
1981 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
1983 fsnotify_create(dir
, dentry
);
1987 static int may_mknod(mode_t mode
)
1989 switch (mode
& S_IFMT
) {
1995 case 0: /* zero mode translates to S_IFREG */
2004 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, int, mode
,
2009 struct dentry
*dentry
;
2010 struct nameidata nd
;
2015 error
= user_path_parent(dfd
, filename
, &nd
, &tmp
);
2019 dentry
= lookup_create(&nd
, 0);
2020 if (IS_ERR(dentry
)) {
2021 error
= PTR_ERR(dentry
);
2024 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2025 mode
&= ~current
->fs
->umask
;
2026 error
= may_mknod(mode
);
2029 error
= mnt_want_write(nd
.path
.mnt
);
2032 switch (mode
& S_IFMT
) {
2033 case 0: case S_IFREG
:
2034 error
= vfs_create(nd
.path
.dentry
->d_inode
,dentry
,mode
,&nd
);
2036 case S_IFCHR
: case S_IFBLK
:
2037 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,
2038 new_decode_dev(dev
));
2040 case S_IFIFO
: case S_IFSOCK
:
2041 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,0);
2044 mnt_drop_write(nd
.path
.mnt
);
2048 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2055 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, int, mode
, unsigned, dev
)
2057 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
2060 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
2062 int error
= may_create(dir
, dentry
);
2067 if (!dir
->i_op
|| !dir
->i_op
->mkdir
)
2070 mode
&= (S_IRWXUGO
|S_ISVTX
);
2071 error
= security_inode_mkdir(dir
, dentry
, mode
);
2076 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
2078 fsnotify_mkdir(dir
, dentry
);
2082 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, int, mode
)
2086 struct dentry
*dentry
;
2087 struct nameidata nd
;
2089 error
= user_path_parent(dfd
, pathname
, &nd
, &tmp
);
2093 dentry
= lookup_create(&nd
, 1);
2094 error
= PTR_ERR(dentry
);
2098 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2099 mode
&= ~current
->fs
->umask
;
2100 error
= mnt_want_write(nd
.path
.mnt
);
2103 error
= vfs_mkdir(nd
.path
.dentry
->d_inode
, dentry
, mode
);
2104 mnt_drop_write(nd
.path
.mnt
);
2108 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2115 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, int, mode
)
2117 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
2121 * We try to drop the dentry early: we should have
2122 * a usage count of 2 if we're the only user of this
2123 * dentry, and if that is true (possibly after pruning
2124 * the dcache), then we drop the dentry now.
2126 * A low-level filesystem can, if it choses, legally
2129 * if (!d_unhashed(dentry))
2132 * if it cannot handle the case of removing a directory
2133 * that is still in use by something else..
2135 void dentry_unhash(struct dentry
*dentry
)
2138 shrink_dcache_parent(dentry
);
2139 spin_lock(&dcache_lock
);
2140 spin_lock(&dentry
->d_lock
);
2141 if (atomic_read(&dentry
->d_count
) == 2)
2143 spin_unlock(&dentry
->d_lock
);
2144 spin_unlock(&dcache_lock
);
2147 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2149 int error
= may_delete(dir
, dentry
, 1);
2154 if (!dir
->i_op
|| !dir
->i_op
->rmdir
)
2159 mutex_lock(&dentry
->d_inode
->i_mutex
);
2160 dentry_unhash(dentry
);
2161 if (d_mountpoint(dentry
))
2164 error
= security_inode_rmdir(dir
, dentry
);
2166 error
= dir
->i_op
->rmdir(dir
, dentry
);
2168 dentry
->d_inode
->i_flags
|= S_DEAD
;
2171 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2180 static long do_rmdir(int dfd
, const char __user
*pathname
)
2184 struct dentry
*dentry
;
2185 struct nameidata nd
;
2187 error
= user_path_parent(dfd
, pathname
, &nd
, &name
);
2191 switch(nd
.last_type
) {
2202 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2203 dentry
= lookup_hash(&nd
);
2204 error
= PTR_ERR(dentry
);
2207 error
= mnt_want_write(nd
.path
.mnt
);
2210 error
= vfs_rmdir(nd
.path
.dentry
->d_inode
, dentry
);
2211 mnt_drop_write(nd
.path
.mnt
);
2215 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2222 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
2224 return do_rmdir(AT_FDCWD
, pathname
);
2227 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
)
2229 int error
= may_delete(dir
, dentry
, 0);
2234 if (!dir
->i_op
|| !dir
->i_op
->unlink
)
2239 mutex_lock(&dentry
->d_inode
->i_mutex
);
2240 if (d_mountpoint(dentry
))
2243 error
= security_inode_unlink(dir
, dentry
);
2245 error
= dir
->i_op
->unlink(dir
, dentry
);
2247 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2249 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2250 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
2251 fsnotify_link_count(dentry
->d_inode
);
2259 * Make sure that the actual truncation of the file will occur outside its
2260 * directory's i_mutex. Truncate can take a long time if there is a lot of
2261 * writeout happening, and we don't want to prevent access to the directory
2262 * while waiting on the I/O.
2264 static long do_unlinkat(int dfd
, const char __user
*pathname
)
2268 struct dentry
*dentry
;
2269 struct nameidata nd
;
2270 struct inode
*inode
= NULL
;
2272 error
= user_path_parent(dfd
, pathname
, &nd
, &name
);
2277 if (nd
.last_type
!= LAST_NORM
)
2279 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2280 dentry
= lookup_hash(&nd
);
2281 error
= PTR_ERR(dentry
);
2282 if (!IS_ERR(dentry
)) {
2283 /* Why not before? Because we want correct error value */
2284 if (nd
.last
.name
[nd
.last
.len
])
2286 inode
= dentry
->d_inode
;
2288 atomic_inc(&inode
->i_count
);
2289 error
= mnt_want_write(nd
.path
.mnt
);
2292 error
= vfs_unlink(nd
.path
.dentry
->d_inode
, dentry
);
2293 mnt_drop_write(nd
.path
.mnt
);
2297 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2299 iput(inode
); /* truncate the inode here */
2306 error
= !dentry
->d_inode
? -ENOENT
:
2307 S_ISDIR(dentry
->d_inode
->i_mode
) ? -EISDIR
: -ENOTDIR
;
2311 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
2313 if ((flag
& ~AT_REMOVEDIR
) != 0)
2316 if (flag
& AT_REMOVEDIR
)
2317 return do_rmdir(dfd
, pathname
);
2319 return do_unlinkat(dfd
, pathname
);
2322 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
2324 return do_unlinkat(AT_FDCWD
, pathname
);
2327 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
2329 int error
= may_create(dir
, dentry
);
2334 if (!dir
->i_op
|| !dir
->i_op
->symlink
)
2337 error
= security_inode_symlink(dir
, dentry
, oldname
);
2342 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
2344 fsnotify_create(dir
, dentry
);
2348 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
2349 int, newdfd
, const char __user
*, newname
)
2354 struct dentry
*dentry
;
2355 struct nameidata nd
;
2357 from
= getname(oldname
);
2359 return PTR_ERR(from
);
2361 error
= user_path_parent(newdfd
, newname
, &nd
, &to
);
2365 dentry
= lookup_create(&nd
, 0);
2366 error
= PTR_ERR(dentry
);
2370 error
= mnt_want_write(nd
.path
.mnt
);
2373 error
= vfs_symlink(nd
.path
.dentry
->d_inode
, dentry
, from
);
2374 mnt_drop_write(nd
.path
.mnt
);
2378 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2386 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
2388 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
2391 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
)
2393 struct inode
*inode
= old_dentry
->d_inode
;
2399 error
= may_create(dir
, new_dentry
);
2403 if (dir
->i_sb
!= inode
->i_sb
)
2407 * A link to an append-only or immutable file cannot be created.
2409 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
2411 if (!dir
->i_op
|| !dir
->i_op
->link
)
2413 if (S_ISDIR(inode
->i_mode
))
2416 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
2420 mutex_lock(&inode
->i_mutex
);
2422 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
2423 mutex_unlock(&inode
->i_mutex
);
2425 fsnotify_link(dir
, inode
, new_dentry
);
2430 * Hardlinks are often used in delicate situations. We avoid
2431 * security-related surprises by not following symlinks on the
2434 * We don't follow them on the oldname either to be compatible
2435 * with linux 2.0, and to avoid hard-linking to directories
2436 * and other special files. --ADM
2438 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
2439 int, newdfd
, const char __user
*, newname
, int, flags
)
2441 struct dentry
*new_dentry
;
2442 struct nameidata nd
;
2443 struct path old_path
;
2447 if ((flags
& ~AT_SYMLINK_FOLLOW
) != 0)
2450 error
= user_path_at(olddfd
, oldname
,
2451 flags
& AT_SYMLINK_FOLLOW
? LOOKUP_FOLLOW
: 0,
2456 error
= user_path_parent(newdfd
, newname
, &nd
, &to
);
2460 if (old_path
.mnt
!= nd
.path
.mnt
)
2462 new_dentry
= lookup_create(&nd
, 0);
2463 error
= PTR_ERR(new_dentry
);
2464 if (IS_ERR(new_dentry
))
2466 error
= mnt_want_write(nd
.path
.mnt
);
2469 error
= vfs_link(old_path
.dentry
, nd
.path
.dentry
->d_inode
, new_dentry
);
2470 mnt_drop_write(nd
.path
.mnt
);
2474 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2479 path_put(&old_path
);
2484 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
2486 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
2490 * The worst of all namespace operations - renaming directory. "Perverted"
2491 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2493 * a) we can get into loop creation. Check is done in is_subdir().
2494 * b) race potential - two innocent renames can create a loop together.
2495 * That's where 4.4 screws up. Current fix: serialization on
2496 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2498 * c) we have to lock _three_ objects - parents and victim (if it exists).
2499 * And that - after we got ->i_mutex on parents (until then we don't know
2500 * whether the target exists). Solution: try to be smart with locking
2501 * order for inodes. We rely on the fact that tree topology may change
2502 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2503 * move will be locked. Thus we can rank directories by the tree
2504 * (ancestors first) and rank all non-directories after them.
2505 * That works since everybody except rename does "lock parent, lookup,
2506 * lock child" and rename is under ->s_vfs_rename_mutex.
2507 * HOWEVER, it relies on the assumption that any object with ->lookup()
2508 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2509 * we'd better make sure that there's no link(2) for them.
2510 * d) some filesystems don't support opened-but-unlinked directories,
2511 * either because of layout or because they are not ready to deal with
2512 * all cases correctly. The latter will be fixed (taking this sort of
2513 * stuff into VFS), but the former is not going away. Solution: the same
2514 * trick as in rmdir().
2515 * e) conversion from fhandle to dentry may come in the wrong moment - when
2516 * we are removing the target. Solution: we will have to grab ->i_mutex
2517 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2518 * ->i_mutex on parents, which works but leads to some truely excessive
2521 static int vfs_rename_dir(struct inode
*old_dir
, struct dentry
*old_dentry
,
2522 struct inode
*new_dir
, struct dentry
*new_dentry
)
2525 struct inode
*target
;
2528 * If we are going to change the parent - check write permissions,
2529 * we'll need to flip '..'.
2531 if (new_dir
!= old_dir
) {
2532 error
= inode_permission(old_dentry
->d_inode
, MAY_WRITE
);
2537 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2541 target
= new_dentry
->d_inode
;
2543 mutex_lock(&target
->i_mutex
);
2544 dentry_unhash(new_dentry
);
2546 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2549 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2552 target
->i_flags
|= S_DEAD
;
2553 mutex_unlock(&target
->i_mutex
);
2554 if (d_unhashed(new_dentry
))
2555 d_rehash(new_dentry
);
2559 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2560 d_move(old_dentry
,new_dentry
);
2564 static int vfs_rename_other(struct inode
*old_dir
, struct dentry
*old_dentry
,
2565 struct inode
*new_dir
, struct dentry
*new_dentry
)
2567 struct inode
*target
;
2570 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2575 target
= new_dentry
->d_inode
;
2577 mutex_lock(&target
->i_mutex
);
2578 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2581 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2583 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2584 d_move(old_dentry
, new_dentry
);
2587 mutex_unlock(&target
->i_mutex
);
2592 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2593 struct inode
*new_dir
, struct dentry
*new_dentry
)
2596 int is_dir
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
2597 const char *old_name
;
2599 if (old_dentry
->d_inode
== new_dentry
->d_inode
)
2602 error
= may_delete(old_dir
, old_dentry
, is_dir
);
2606 if (!new_dentry
->d_inode
)
2607 error
= may_create(new_dir
, new_dentry
);
2609 error
= may_delete(new_dir
, new_dentry
, is_dir
);
2613 if (!old_dir
->i_op
|| !old_dir
->i_op
->rename
)
2616 DQUOT_INIT(old_dir
);
2617 DQUOT_INIT(new_dir
);
2619 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
2622 error
= vfs_rename_dir(old_dir
,old_dentry
,new_dir
,new_dentry
);
2624 error
= vfs_rename_other(old_dir
,old_dentry
,new_dir
,new_dentry
);
2626 const char *new_name
= old_dentry
->d_name
.name
;
2627 fsnotify_move(old_dir
, new_dir
, old_name
, new_name
, is_dir
,
2628 new_dentry
->d_inode
, old_dentry
);
2630 fsnotify_oldname_free(old_name
);
2635 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
2636 int, newdfd
, const char __user
*, newname
)
2638 struct dentry
*old_dir
, *new_dir
;
2639 struct dentry
*old_dentry
, *new_dentry
;
2640 struct dentry
*trap
;
2641 struct nameidata oldnd
, newnd
;
2646 error
= user_path_parent(olddfd
, oldname
, &oldnd
, &from
);
2650 error
= user_path_parent(newdfd
, newname
, &newnd
, &to
);
2655 if (oldnd
.path
.mnt
!= newnd
.path
.mnt
)
2658 old_dir
= oldnd
.path
.dentry
;
2660 if (oldnd
.last_type
!= LAST_NORM
)
2663 new_dir
= newnd
.path
.dentry
;
2664 if (newnd
.last_type
!= LAST_NORM
)
2667 trap
= lock_rename(new_dir
, old_dir
);
2669 old_dentry
= lookup_hash(&oldnd
);
2670 error
= PTR_ERR(old_dentry
);
2671 if (IS_ERR(old_dentry
))
2673 /* source must exist */
2675 if (!old_dentry
->d_inode
)
2677 /* unless the source is a directory trailing slashes give -ENOTDIR */
2678 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
)) {
2680 if (oldnd
.last
.name
[oldnd
.last
.len
])
2682 if (newnd
.last
.name
[newnd
.last
.len
])
2685 /* source should not be ancestor of target */
2687 if (old_dentry
== trap
)
2689 new_dentry
= lookup_hash(&newnd
);
2690 error
= PTR_ERR(new_dentry
);
2691 if (IS_ERR(new_dentry
))
2693 /* target should not be an ancestor of source */
2695 if (new_dentry
== trap
)
2698 error
= mnt_want_write(oldnd
.path
.mnt
);
2701 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
2702 new_dir
->d_inode
, new_dentry
);
2703 mnt_drop_write(oldnd
.path
.mnt
);
2709 unlock_rename(new_dir
, old_dir
);
2711 path_put(&newnd
.path
);
2714 path_put(&oldnd
.path
);
2720 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
2722 return sys_renameat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
);
2725 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
, const char *link
)
2729 len
= PTR_ERR(link
);
2734 if (len
> (unsigned) buflen
)
2736 if (copy_to_user(buffer
, link
, len
))
2743 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2744 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2745 * using) it for any given inode is up to filesystem.
2747 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2749 struct nameidata nd
;
2754 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
2756 return PTR_ERR(cookie
);
2758 res
= vfs_readlink(dentry
, buffer
, buflen
, nd_get_link(&nd
));
2759 if (dentry
->d_inode
->i_op
->put_link
)
2760 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
2764 int vfs_follow_link(struct nameidata
*nd
, const char *link
)
2766 return __vfs_follow_link(nd
, link
);
2769 /* get the link contents into pagecache */
2770 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
2773 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
2774 page
= read_mapping_page(mapping
, 0, NULL
);
2781 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2783 struct page
*page
= NULL
;
2784 char *s
= page_getlink(dentry
, &page
);
2785 int res
= vfs_readlink(dentry
,buffer
,buflen
,s
);
2788 page_cache_release(page
);
2793 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
2795 struct page
*page
= NULL
;
2796 nd_set_link(nd
, page_getlink(dentry
, &page
));
2800 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2802 struct page
*page
= cookie
;
2806 page_cache_release(page
);
2811 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
2813 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
2815 struct address_space
*mapping
= inode
->i_mapping
;
2820 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
2822 flags
|= AOP_FLAG_NOFS
;
2825 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
2826 flags
, &page
, &fsdata
);
2830 kaddr
= kmap_atomic(page
, KM_USER0
);
2831 memcpy(kaddr
, symname
, len
-1);
2832 kunmap_atomic(kaddr
, KM_USER0
);
2834 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
2841 mark_inode_dirty(inode
);
2847 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
2849 return __page_symlink(inode
, symname
, len
,
2850 !(mapping_gfp_mask(inode
->i_mapping
) & __GFP_FS
));
2853 const struct inode_operations page_symlink_inode_operations
= {
2854 .readlink
= generic_readlink
,
2855 .follow_link
= page_follow_link_light
,
2856 .put_link
= page_put_link
,
2859 EXPORT_SYMBOL(user_path_at
);
2860 EXPORT_SYMBOL(follow_down
);
2861 EXPORT_SYMBOL(follow_up
);
2862 EXPORT_SYMBOL(get_write_access
); /* binfmt_aout */
2863 EXPORT_SYMBOL(getname
);
2864 EXPORT_SYMBOL(lock_rename
);
2865 EXPORT_SYMBOL(lookup_one_len
);
2866 EXPORT_SYMBOL(page_follow_link_light
);
2867 EXPORT_SYMBOL(page_put_link
);
2868 EXPORT_SYMBOL(page_readlink
);
2869 EXPORT_SYMBOL(__page_symlink
);
2870 EXPORT_SYMBOL(page_symlink
);
2871 EXPORT_SYMBOL(page_symlink_inode_operations
);
2872 EXPORT_SYMBOL(path_lookup
);
2873 EXPORT_SYMBOL(vfs_path_lookup
);
2874 EXPORT_SYMBOL(inode_permission
);
2875 EXPORT_SYMBOL(vfs_permission
);
2876 EXPORT_SYMBOL(file_permission
);
2877 EXPORT_SYMBOL(unlock_rename
);
2878 EXPORT_SYMBOL(vfs_create
);
2879 EXPORT_SYMBOL(vfs_follow_link
);
2880 EXPORT_SYMBOL(vfs_link
);
2881 EXPORT_SYMBOL(vfs_mkdir
);
2882 EXPORT_SYMBOL(vfs_mknod
);
2883 EXPORT_SYMBOL(generic_permission
);
2884 EXPORT_SYMBOL(vfs_readlink
);
2885 EXPORT_SYMBOL(vfs_rename
);
2886 EXPORT_SYMBOL(vfs_rmdir
);
2887 EXPORT_SYMBOL(vfs_symlink
);
2888 EXPORT_SYMBOL(vfs_unlink
);
2889 EXPORT_SYMBOL(dentry_unhash
);
2890 EXPORT_SYMBOL(generic_readlink
);