4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * Some corrections by tytso.
11 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
14 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
21 #include <linux/namei.h>
22 #include <linux/pagemap.h>
23 #include <linux/fsnotify.h>
24 #include <linux/personality.h>
25 #include <linux/security.h>
26 #include <linux/ima.h>
27 #include <linux/syscalls.h>
28 #include <linux/mount.h>
29 #include <linux/audit.h>
30 #include <linux/capability.h>
31 #include <linux/file.h>
32 #include <linux/fcntl.h>
33 #include <linux/device_cgroup.h>
34 #include <linux/fs_struct.h>
35 #include <asm/uaccess.h>
39 /* [Feb-1997 T. Schoebel-Theuer]
40 * Fundamental changes in the pathname lookup mechanisms (namei)
41 * were necessary because of omirr. The reason is that omirr needs
42 * to know the _real_ pathname, not the user-supplied one, in case
43 * of symlinks (and also when transname replacements occur).
45 * The new code replaces the old recursive symlink resolution with
46 * an iterative one (in case of non-nested symlink chains). It does
47 * this with calls to <fs>_follow_link().
48 * As a side effect, dir_namei(), _namei() and follow_link() are now
49 * replaced with a single function lookup_dentry() that can handle all
50 * the special cases of the former code.
52 * With the new dcache, the pathname is stored at each inode, at least as
53 * long as the refcount of the inode is positive. As a side effect, the
54 * size of the dcache depends on the inode cache and thus is dynamic.
56 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
57 * resolution to correspond with current state of the code.
59 * Note that the symlink resolution is not *completely* iterative.
60 * There is still a significant amount of tail- and mid- recursion in
61 * the algorithm. Also, note that <fs>_readlink() is not used in
62 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
63 * may return different results than <fs>_follow_link(). Many virtual
64 * filesystems (including /proc) exhibit this behavior.
67 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
68 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
69 * and the name already exists in form of a symlink, try to create the new
70 * name indicated by the symlink. The old code always complained that the
71 * name already exists, due to not following the symlink even if its target
72 * is nonexistent. The new semantics affects also mknod() and link() when
73 * the name is a symlink pointing to a non-existant name.
75 * I don't know which semantics is the right one, since I have no access
76 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
77 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
78 * "old" one. Personally, I think the new semantics is much more logical.
79 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
80 * file does succeed in both HP-UX and SunOs, but not in Solaris
81 * and in the old Linux semantics.
84 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
85 * semantics. See the comments in "open_namei" and "do_link" below.
87 * [10-Sep-98 Alan Modra] Another symlink change.
90 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
91 * inside the path - always follow.
92 * in the last component in creation/removal/renaming - never follow.
93 * if LOOKUP_FOLLOW passed - follow.
94 * if the pathname has trailing slashes - follow.
95 * otherwise - don't follow.
96 * (applied in that order).
98 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
99 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
100 * During the 2.4 we need to fix the userland stuff depending on it -
101 * hopefully we will be able to get rid of that wart in 2.5. So far only
102 * XEmacs seems to be relying on it...
105 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
106 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
107 * any extra contention...
110 /* In order to reduce some races, while at the same time doing additional
111 * checking and hopefully speeding things up, we copy filenames to the
112 * kernel data space before using them..
114 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
115 * PATH_MAX includes the nul terminator --RR.
117 static int do_getname(const char __user
*filename
, char *page
)
120 unsigned long len
= PATH_MAX
;
122 if (!segment_eq(get_fs(), KERNEL_DS
)) {
123 if ((unsigned long) filename
>= TASK_SIZE
)
125 if (TASK_SIZE
- (unsigned long) filename
< PATH_MAX
)
126 len
= TASK_SIZE
- (unsigned long) filename
;
129 retval
= strncpy_from_user(page
, filename
, len
);
133 return -ENAMETOOLONG
;
139 char * getname(const char __user
* filename
)
143 result
= ERR_PTR(-ENOMEM
);
146 int retval
= do_getname(filename
, tmp
);
151 result
= ERR_PTR(retval
);
154 audit_getname(result
);
158 #ifdef CONFIG_AUDITSYSCALL
159 void putname(const char *name
)
161 if (unlikely(!audit_dummy_context()))
166 EXPORT_SYMBOL(putname
);
170 * This does basic POSIX ACL permission checking
172 static int acl_permission_check(struct inode
*inode
, int mask
,
173 int (*check_acl
)(struct inode
*inode
, int mask
))
175 umode_t mode
= inode
->i_mode
;
177 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
179 if (current_fsuid() == inode
->i_uid
)
182 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
) && check_acl
) {
183 int error
= check_acl(inode
, mask
);
184 if (error
!= -EAGAIN
)
188 if (in_group_p(inode
->i_gid
))
193 * If the DACs are ok we don't need any capability check.
195 if ((mask
& ~mode
) == 0)
201 * generic_permission - check for access rights on a Posix-like filesystem
202 * @inode: inode to check access rights for
203 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
204 * @check_acl: optional callback to check for Posix ACLs
206 * Used to check for read/write/execute permissions on a file.
207 * We use "fsuid" for this, letting us set arbitrary permissions
208 * for filesystem access without changing the "normal" uids which
209 * are used for other things..
211 int generic_permission(struct inode
*inode
, int mask
,
212 int (*check_acl
)(struct inode
*inode
, int mask
))
217 * Do the basic POSIX ACL permission checks.
219 ret
= acl_permission_check(inode
, mask
, check_acl
);
224 * Read/write DACs are always overridable.
225 * Executable DACs are overridable if at least one exec bit is set.
227 if (!(mask
& MAY_EXEC
) || execute_ok(inode
))
228 if (capable(CAP_DAC_OVERRIDE
))
232 * Searching includes executable on directories, else just read.
234 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
235 if (mask
== MAY_READ
|| (S_ISDIR(inode
->i_mode
) && !(mask
& MAY_WRITE
)))
236 if (capable(CAP_DAC_READ_SEARCH
))
243 * inode_permission - check for access rights to a given inode
244 * @inode: inode to check permission on
245 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
247 * Used to check for read/write/execute permissions on an inode.
248 * We use "fsuid" for this, letting us set arbitrary permissions
249 * for filesystem access without changing the "normal" uids which
250 * are used for other things.
252 int inode_permission(struct inode
*inode
, int mask
)
256 if (mask
& MAY_WRITE
) {
257 umode_t mode
= inode
->i_mode
;
260 * Nobody gets write access to a read-only fs.
262 if (IS_RDONLY(inode
) &&
263 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
267 * Nobody gets write access to an immutable file.
269 if (IS_IMMUTABLE(inode
))
273 if (inode
->i_op
->permission
)
274 retval
= inode
->i_op
->permission(inode
, mask
);
276 retval
= generic_permission(inode
, mask
, inode
->i_op
->check_acl
);
281 retval
= devcgroup_inode_permission(inode
, mask
);
285 return security_inode_permission(inode
, mask
);
289 * file_permission - check for additional access rights to a given file
290 * @file: file to check access rights for
291 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
293 * Used to check for read/write/execute permissions on an already opened
297 * Do not use this function in new code. All access checks should
298 * be done using inode_permission().
300 int file_permission(struct file
*file
, int mask
)
302 return inode_permission(file
->f_path
.dentry
->d_inode
, mask
);
306 * get_write_access() gets write permission for a file.
307 * put_write_access() releases this write permission.
308 * This is used for regular files.
309 * We cannot support write (and maybe mmap read-write shared) accesses and
310 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
311 * can have the following values:
312 * 0: no writers, no VM_DENYWRITE mappings
313 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
314 * > 0: (i_writecount) users are writing to the file.
316 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
317 * except for the cases where we don't hold i_writecount yet. Then we need to
318 * use {get,deny}_write_access() - these functions check the sign and refuse
319 * to do the change if sign is wrong. Exclusion between them is provided by
320 * the inode->i_lock spinlock.
323 int get_write_access(struct inode
* inode
)
325 spin_lock(&inode
->i_lock
);
326 if (atomic_read(&inode
->i_writecount
) < 0) {
327 spin_unlock(&inode
->i_lock
);
330 atomic_inc(&inode
->i_writecount
);
331 spin_unlock(&inode
->i_lock
);
336 int deny_write_access(struct file
* file
)
338 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
340 spin_lock(&inode
->i_lock
);
341 if (atomic_read(&inode
->i_writecount
) > 0) {
342 spin_unlock(&inode
->i_lock
);
345 atomic_dec(&inode
->i_writecount
);
346 spin_unlock(&inode
->i_lock
);
352 * path_get - get a reference to a path
353 * @path: path to get the reference to
355 * Given a path increment the reference count to the dentry and the vfsmount.
357 void path_get(struct path
*path
)
362 EXPORT_SYMBOL(path_get
);
365 * path_put - put a reference to a path
366 * @path: path to put the reference to
368 * Given a path decrement the reference count to the dentry and the vfsmount.
370 void path_put(struct path
*path
)
375 EXPORT_SYMBOL(path_put
);
378 * release_open_intent - free up open intent resources
379 * @nd: pointer to nameidata
381 void release_open_intent(struct nameidata
*nd
)
383 if (nd
->intent
.open
.file
->f_path
.dentry
== NULL
)
384 put_filp(nd
->intent
.open
.file
);
386 fput(nd
->intent
.open
.file
);
389 static inline struct dentry
*
390 do_revalidate(struct dentry
*dentry
, struct nameidata
*nd
)
392 int status
= dentry
->d_op
->d_revalidate(dentry
, nd
);
393 if (unlikely(status
<= 0)) {
395 * The dentry failed validation.
396 * If d_revalidate returned 0 attempt to invalidate
397 * the dentry otherwise d_revalidate is asking us
398 * to return a fail status.
401 if (!d_invalidate(dentry
)) {
407 dentry
= ERR_PTR(status
);
414 * force_reval_path - force revalidation of a dentry
416 * In some situations the path walking code will trust dentries without
417 * revalidating them. This causes problems for filesystems that depend on
418 * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set
419 * (which indicates that it's possible for the dentry to go stale), force
420 * a d_revalidate call before proceeding.
422 * Returns 0 if the revalidation was successful. If the revalidation fails,
423 * either return the error returned by d_revalidate or -ESTALE if the
424 * revalidation it just returned 0. If d_revalidate returns 0, we attempt to
425 * invalidate the dentry. It's up to the caller to handle putting references
426 * to the path if necessary.
429 force_reval_path(struct path
*path
, struct nameidata
*nd
)
432 struct dentry
*dentry
= path
->dentry
;
435 * only check on filesystems where it's possible for the dentry to
436 * become stale. It's assumed that if this flag is set then the
437 * d_revalidate op will also be defined.
439 if (!(dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
))
442 status
= dentry
->d_op
->d_revalidate(dentry
, nd
);
447 d_invalidate(dentry
);
454 * Short-cut version of permission(), for calling on directories
455 * during pathname resolution. Combines parts of permission()
456 * and generic_permission(), and tests ONLY for MAY_EXEC permission.
458 * If appropriate, check DAC only. If not appropriate, or
459 * short-cut DAC fails, then call ->permission() to do more
460 * complete permission check.
462 static int exec_permission(struct inode
*inode
)
466 if (inode
->i_op
->permission
) {
467 ret
= inode
->i_op
->permission(inode
, MAY_EXEC
);
472 ret
= acl_permission_check(inode
, MAY_EXEC
, inode
->i_op
->check_acl
);
476 if (capable(CAP_DAC_OVERRIDE
) || capable(CAP_DAC_READ_SEARCH
))
481 return security_inode_permission(inode
, MAY_EXEC
);
484 static __always_inline
void set_root(struct nameidata
*nd
)
487 get_fs_root(current
->fs
, &nd
->root
);
490 static int link_path_walk(const char *, struct nameidata
*);
492 static __always_inline
int __vfs_follow_link(struct nameidata
*nd
, const char *link
)
504 return link_path_walk(link
, nd
);
507 return PTR_ERR(link
);
510 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
513 if (path
->mnt
!= nd
->path
.mnt
)
517 static inline void path_to_nameidata(struct path
*path
, struct nameidata
*nd
)
519 dput(nd
->path
.dentry
);
520 if (nd
->path
.mnt
!= path
->mnt
) {
521 mntput(nd
->path
.mnt
);
522 nd
->path
.mnt
= path
->mnt
;
524 nd
->path
.dentry
= path
->dentry
;
527 static __always_inline
int
528 __do_follow_link(struct path
*path
, struct nameidata
*nd
, void **p
)
531 struct dentry
*dentry
= path
->dentry
;
533 touch_atime(path
->mnt
, dentry
);
534 nd_set_link(nd
, NULL
);
536 if (path
->mnt
!= nd
->path
.mnt
) {
537 path_to_nameidata(path
, nd
);
541 nd
->last_type
= LAST_BIND
;
542 *p
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
545 char *s
= nd_get_link(nd
);
548 error
= __vfs_follow_link(nd
, s
);
549 else if (nd
->last_type
== LAST_BIND
) {
550 error
= force_reval_path(&nd
->path
, nd
);
559 * This limits recursive symlink follows to 8, while
560 * limiting consecutive symlinks to 40.
562 * Without that kind of total limit, nasty chains of consecutive
563 * symlinks can cause almost arbitrarily long lookups.
565 static inline int do_follow_link(struct path
*path
, struct nameidata
*nd
)
569 if (current
->link_count
>= MAX_NESTED_LINKS
)
571 if (current
->total_link_count
>= 40)
573 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
575 err
= security_inode_follow_link(path
->dentry
, nd
);
578 current
->link_count
++;
579 current
->total_link_count
++;
581 err
= __do_follow_link(path
, nd
, &cookie
);
582 if (!IS_ERR(cookie
) && path
->dentry
->d_inode
->i_op
->put_link
)
583 path
->dentry
->d_inode
->i_op
->put_link(path
->dentry
, nd
, cookie
);
585 current
->link_count
--;
589 path_put_conditional(path
, nd
);
594 int follow_up(struct path
*path
)
596 struct vfsmount
*parent
;
597 struct dentry
*mountpoint
;
599 br_read_lock(vfsmount_lock
);
600 parent
= path
->mnt
->mnt_parent
;
601 if (parent
== path
->mnt
) {
602 br_read_unlock(vfsmount_lock
);
606 mountpoint
= dget(path
->mnt
->mnt_mountpoint
);
607 br_read_unlock(vfsmount_lock
);
609 path
->dentry
= mountpoint
;
616 * serialization is taken care of in namespace.c
618 static int __follow_mount(struct path
*path
)
621 while (d_mountpoint(path
->dentry
)) {
622 struct vfsmount
*mounted
= lookup_mnt(path
);
629 path
->dentry
= dget(mounted
->mnt_root
);
635 static void follow_mount(struct path
*path
)
637 while (d_mountpoint(path
->dentry
)) {
638 struct vfsmount
*mounted
= lookup_mnt(path
);
644 path
->dentry
= dget(mounted
->mnt_root
);
648 int follow_down(struct path
*path
)
650 struct vfsmount
*mounted
;
652 mounted
= lookup_mnt(path
);
657 path
->dentry
= dget(mounted
->mnt_root
);
663 static __always_inline
void follow_dotdot(struct nameidata
*nd
)
668 struct dentry
*old
= nd
->path
.dentry
;
670 if (nd
->path
.dentry
== nd
->root
.dentry
&&
671 nd
->path
.mnt
== nd
->root
.mnt
) {
674 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
675 /* rare case of legitimate dget_parent()... */
676 nd
->path
.dentry
= dget_parent(nd
->path
.dentry
);
680 if (!follow_up(&nd
->path
))
683 follow_mount(&nd
->path
);
687 * Allocate a dentry with name and parent, and perform a parent
688 * directory ->lookup on it. Returns the new dentry, or ERR_PTR
689 * on error. parent->d_inode->i_mutex must be held. d_lookup must
690 * have verified that no child exists while under i_mutex.
692 static struct dentry
*d_alloc_and_lookup(struct dentry
*parent
,
693 struct qstr
*name
, struct nameidata
*nd
)
695 struct inode
*inode
= parent
->d_inode
;
696 struct dentry
*dentry
;
699 /* Don't create child dentry for a dead directory. */
700 if (unlikely(IS_DEADDIR(inode
)))
701 return ERR_PTR(-ENOENT
);
703 dentry
= d_alloc(parent
, name
);
704 if (unlikely(!dentry
))
705 return ERR_PTR(-ENOMEM
);
707 old
= inode
->i_op
->lookup(inode
, dentry
, nd
);
716 * It's more convoluted than I'd like it to be, but... it's still fairly
717 * small and for now I'd prefer to have fast path as straight as possible.
718 * It _is_ time-critical.
720 static int do_lookup(struct nameidata
*nd
, struct qstr
*name
,
723 struct vfsmount
*mnt
= nd
->path
.mnt
;
724 struct dentry
*dentry
, *parent
;
727 * See if the low-level filesystem might want
728 * to use its own hash..
730 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
731 int err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
732 nd
->path
.dentry
->d_inode
, name
);
738 * Rename seqlock is not required here because in the off chance
739 * of a false negative due to a concurrent rename, we're going to
740 * do the non-racy lookup, below.
742 dentry
= __d_lookup(nd
->path
.dentry
, name
);
746 if (dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
747 goto need_revalidate
;
750 path
->dentry
= dentry
;
751 __follow_mount(path
);
755 parent
= nd
->path
.dentry
;
756 dir
= parent
->d_inode
;
758 mutex_lock(&dir
->i_mutex
);
760 * First re-do the cached lookup just in case it was created
761 * while we waited for the directory semaphore, or the first
762 * lookup failed due to an unrelated rename.
764 * This could use version numbering or similar to avoid unnecessary
765 * cache lookups, but then we'd have to do the first lookup in the
766 * non-racy way. However in the common case here, everything should
767 * be hot in cache, so would it be a big win?
769 dentry
= d_lookup(parent
, name
);
770 if (likely(!dentry
)) {
771 dentry
= d_alloc_and_lookup(parent
, name
, nd
);
772 mutex_unlock(&dir
->i_mutex
);
778 * Uhhuh! Nasty case: the cache was re-populated while
779 * we waited on the semaphore. Need to revalidate.
781 mutex_unlock(&dir
->i_mutex
);
785 dentry
= do_revalidate(dentry
, nd
);
793 return PTR_ERR(dentry
);
797 * This is a temporary kludge to deal with "automount" symlinks; proper
798 * solution is to trigger them on follow_mount(), so that do_lookup()
799 * would DTRT. To be killed before 2.6.34-final.
801 static inline int follow_on_final(struct inode
*inode
, unsigned lookup_flags
)
803 return inode
&& unlikely(inode
->i_op
->follow_link
) &&
804 ((lookup_flags
& LOOKUP_FOLLOW
) || S_ISDIR(inode
->i_mode
));
809 * This is the basic name resolution function, turning a pathname into
810 * the final dentry. We expect 'base' to be positive and a directory.
812 * Returns 0 and nd will have valid dentry and mnt on success.
813 * Returns error and drops reference to input namei data on failure.
815 static int link_path_walk(const char *name
, struct nameidata
*nd
)
820 unsigned int lookup_flags
= nd
->flags
;
827 inode
= nd
->path
.dentry
->d_inode
;
829 lookup_flags
= LOOKUP_FOLLOW
| (nd
->flags
& LOOKUP_CONTINUE
);
831 /* At this point we know we have a real path component. */
837 nd
->flags
|= LOOKUP_CONTINUE
;
838 err
= exec_permission(inode
);
843 c
= *(const unsigned char *)name
;
845 hash
= init_name_hash();
848 hash
= partial_name_hash(c
, hash
);
849 c
= *(const unsigned char *)name
;
850 } while (c
&& (c
!= '/'));
851 this.len
= name
- (const char *) this.name
;
852 this.hash
= end_name_hash(hash
);
854 /* remove trailing slashes? */
857 while (*++name
== '/');
859 goto last_with_slashes
;
862 * "." and ".." are special - ".." especially so because it has
863 * to be able to know about the current root directory and
864 * parent relationships.
866 if (this.name
[0] == '.') switch (this.len
) {
870 if (this.name
[1] != '.')
873 inode
= nd
->path
.dentry
->d_inode
;
878 /* This does the actual lookups.. */
879 err
= do_lookup(nd
, &this, &next
);
884 inode
= next
.dentry
->d_inode
;
888 if (inode
->i_op
->follow_link
) {
889 err
= do_follow_link(&next
, nd
);
893 inode
= nd
->path
.dentry
->d_inode
;
897 path_to_nameidata(&next
, nd
);
899 if (!inode
->i_op
->lookup
)
902 /* here ends the main loop */
905 lookup_flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
907 /* Clear LOOKUP_CONTINUE iff it was previously unset */
908 nd
->flags
&= lookup_flags
| ~LOOKUP_CONTINUE
;
909 if (lookup_flags
& LOOKUP_PARENT
)
911 if (this.name
[0] == '.') switch (this.len
) {
915 if (this.name
[1] != '.')
918 inode
= nd
->path
.dentry
->d_inode
;
923 err
= do_lookup(nd
, &this, &next
);
926 inode
= next
.dentry
->d_inode
;
927 if (follow_on_final(inode
, lookup_flags
)) {
928 err
= do_follow_link(&next
, nd
);
931 inode
= nd
->path
.dentry
->d_inode
;
933 path_to_nameidata(&next
, nd
);
937 if (lookup_flags
& LOOKUP_DIRECTORY
) {
939 if (!inode
->i_op
->lookup
)
945 nd
->last_type
= LAST_NORM
;
946 if (this.name
[0] != '.')
949 nd
->last_type
= LAST_DOT
;
950 else if (this.len
== 2 && this.name
[1] == '.')
951 nd
->last_type
= LAST_DOTDOT
;
956 * We bypassed the ordinary revalidation routines.
957 * We may need to check the cached dentry for staleness.
959 if (nd
->path
.dentry
&& nd
->path
.dentry
->d_sb
&&
960 (nd
->path
.dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
)) {
962 /* Note: we do not d_invalidate() */
963 if (!nd
->path
.dentry
->d_op
->d_revalidate(
964 nd
->path
.dentry
, nd
))
970 path_put_conditional(&next
, nd
);
978 static int path_walk(const char *name
, struct nameidata
*nd
)
980 struct path save
= nd
->path
;
983 current
->total_link_count
= 0;
985 /* make sure the stuff we saved doesn't go away */
988 result
= link_path_walk(name
, nd
);
989 if (result
== -ESTALE
) {
990 /* nd->path had been dropped */
991 current
->total_link_count
= 0;
994 nd
->flags
|= LOOKUP_REVAL
;
995 result
= link_path_walk(name
, nd
);
1003 static int path_init(int dfd
, const char *name
, unsigned int flags
, struct nameidata
*nd
)
1009 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1012 nd
->root
.mnt
= NULL
;
1016 nd
->path
= nd
->root
;
1017 path_get(&nd
->root
);
1018 } else if (dfd
== AT_FDCWD
) {
1019 get_fs_pwd(current
->fs
, &nd
->path
);
1021 struct dentry
*dentry
;
1023 file
= fget_light(dfd
, &fput_needed
);
1028 dentry
= file
->f_path
.dentry
;
1031 if (!S_ISDIR(dentry
->d_inode
->i_mode
))
1034 retval
= file_permission(file
, MAY_EXEC
);
1038 nd
->path
= file
->f_path
;
1039 path_get(&file
->f_path
);
1041 fput_light(file
, fput_needed
);
1046 fput_light(file
, fput_needed
);
1051 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1052 static int do_path_lookup(int dfd
, const char *name
,
1053 unsigned int flags
, struct nameidata
*nd
)
1055 int retval
= path_init(dfd
, name
, flags
, nd
);
1057 retval
= path_walk(name
, nd
);
1058 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1059 nd
->path
.dentry
->d_inode
))
1060 audit_inode(name
, nd
->path
.dentry
);
1062 path_put(&nd
->root
);
1063 nd
->root
.mnt
= NULL
;
1068 int path_lookup(const char *name
, unsigned int flags
,
1069 struct nameidata
*nd
)
1071 return do_path_lookup(AT_FDCWD
, name
, flags
, nd
);
1074 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
1076 struct nameidata nd
;
1077 int res
= do_path_lookup(AT_FDCWD
, name
, flags
, &nd
);
1084 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1085 * @dentry: pointer to dentry of the base directory
1086 * @mnt: pointer to vfs mount of the base directory
1087 * @name: pointer to file name
1088 * @flags: lookup flags
1089 * @nd: pointer to nameidata
1091 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
1092 const char *name
, unsigned int flags
,
1093 struct nameidata
*nd
)
1097 /* same as do_path_lookup */
1098 nd
->last_type
= LAST_ROOT
;
1102 nd
->path
.dentry
= dentry
;
1104 path_get(&nd
->path
);
1105 nd
->root
= nd
->path
;
1106 path_get(&nd
->root
);
1108 retval
= path_walk(name
, nd
);
1109 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1110 nd
->path
.dentry
->d_inode
))
1111 audit_inode(name
, nd
->path
.dentry
);
1113 path_put(&nd
->root
);
1114 nd
->root
.mnt
= NULL
;
1119 static struct dentry
*__lookup_hash(struct qstr
*name
,
1120 struct dentry
*base
, struct nameidata
*nd
)
1122 struct inode
*inode
= base
->d_inode
;
1123 struct dentry
*dentry
;
1126 err
= exec_permission(inode
);
1128 return ERR_PTR(err
);
1131 * See if the low-level filesystem might want
1132 * to use its own hash..
1134 if (base
->d_op
&& base
->d_op
->d_hash
) {
1135 err
= base
->d_op
->d_hash(base
, inode
, name
);
1136 dentry
= ERR_PTR(err
);
1142 * Don't bother with __d_lookup: callers are for creat as
1143 * well as unlink, so a lot of the time it would cost
1146 dentry
= d_lookup(base
, name
);
1148 if (dentry
&& dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
1149 dentry
= do_revalidate(dentry
, nd
);
1152 dentry
= d_alloc_and_lookup(base
, name
, nd
);
1158 * Restricted form of lookup. Doesn't follow links, single-component only,
1159 * needs parent already locked. Doesn't follow mounts.
1162 static struct dentry
*lookup_hash(struct nameidata
*nd
)
1164 return __lookup_hash(&nd
->last
, nd
->path
.dentry
, nd
);
1167 static int __lookup_one_len(const char *name
, struct qstr
*this,
1168 struct dentry
*base
, int len
)
1178 hash
= init_name_hash();
1180 c
= *(const unsigned char *)name
++;
1181 if (c
== '/' || c
== '\0')
1183 hash
= partial_name_hash(c
, hash
);
1185 this->hash
= end_name_hash(hash
);
1190 * lookup_one_len - filesystem helper to lookup single pathname component
1191 * @name: pathname component to lookup
1192 * @base: base directory to lookup from
1193 * @len: maximum length @len should be interpreted to
1195 * Note that this routine is purely a helper for filesystem usage and should
1196 * not be called by generic code. Also note that by using this function the
1197 * nameidata argument is passed to the filesystem methods and a filesystem
1198 * using this helper needs to be prepared for that.
1200 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
1205 WARN_ON_ONCE(!mutex_is_locked(&base
->d_inode
->i_mutex
));
1207 err
= __lookup_one_len(name
, &this, base
, len
);
1209 return ERR_PTR(err
);
1211 return __lookup_hash(&this, base
, NULL
);
1214 int user_path_at(int dfd
, const char __user
*name
, unsigned flags
,
1217 struct nameidata nd
;
1218 char *tmp
= getname(name
);
1219 int err
= PTR_ERR(tmp
);
1222 BUG_ON(flags
& LOOKUP_PARENT
);
1224 err
= do_path_lookup(dfd
, tmp
, flags
, &nd
);
1232 static int user_path_parent(int dfd
, const char __user
*path
,
1233 struct nameidata
*nd
, char **name
)
1235 char *s
= getname(path
);
1241 error
= do_path_lookup(dfd
, s
, LOOKUP_PARENT
, nd
);
1251 * It's inline, so penalty for filesystems that don't use sticky bit is
1254 static inline int check_sticky(struct inode
*dir
, struct inode
*inode
)
1256 uid_t fsuid
= current_fsuid();
1258 if (!(dir
->i_mode
& S_ISVTX
))
1260 if (inode
->i_uid
== fsuid
)
1262 if (dir
->i_uid
== fsuid
)
1264 return !capable(CAP_FOWNER
);
1268 * Check whether we can remove a link victim from directory dir, check
1269 * whether the type of victim is right.
1270 * 1. We can't do it if dir is read-only (done in permission())
1271 * 2. We should have write and exec permissions on dir
1272 * 3. We can't remove anything from append-only dir
1273 * 4. We can't do anything with immutable dir (done in permission())
1274 * 5. If the sticky bit on dir is set we should either
1275 * a. be owner of dir, or
1276 * b. be owner of victim, or
1277 * c. have CAP_FOWNER capability
1278 * 6. If the victim is append-only or immutable we can't do antyhing with
1279 * links pointing to it.
1280 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1281 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1282 * 9. We can't remove a root or mountpoint.
1283 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1284 * nfs_async_unlink().
1286 static int may_delete(struct inode
*dir
,struct dentry
*victim
,int isdir
)
1290 if (!victim
->d_inode
)
1293 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
1294 audit_inode_child(victim
, dir
);
1296 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
1301 if (check_sticky(dir
, victim
->d_inode
)||IS_APPEND(victim
->d_inode
)||
1302 IS_IMMUTABLE(victim
->d_inode
) || IS_SWAPFILE(victim
->d_inode
))
1305 if (!S_ISDIR(victim
->d_inode
->i_mode
))
1307 if (IS_ROOT(victim
))
1309 } else if (S_ISDIR(victim
->d_inode
->i_mode
))
1311 if (IS_DEADDIR(dir
))
1313 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
1318 /* Check whether we can create an object with dentry child in directory
1320 * 1. We can't do it if child already exists (open has special treatment for
1321 * this case, but since we are inlined it's OK)
1322 * 2. We can't do it if dir is read-only (done in permission())
1323 * 3. We should have write and exec permissions on dir
1324 * 4. We can't do it if dir is immutable (done in permission())
1326 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
1330 if (IS_DEADDIR(dir
))
1332 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
1336 * p1 and p2 should be directories on the same fs.
1338 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
1343 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1347 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1349 p
= d_ancestor(p2
, p1
);
1351 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1352 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1356 p
= d_ancestor(p1
, p2
);
1358 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1359 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1363 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1364 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1368 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
1370 mutex_unlock(&p1
->d_inode
->i_mutex
);
1372 mutex_unlock(&p2
->d_inode
->i_mutex
);
1373 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1377 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1378 struct nameidata
*nd
)
1380 int error
= may_create(dir
, dentry
);
1385 if (!dir
->i_op
->create
)
1386 return -EACCES
; /* shouldn't it be ENOSYS? */
1389 error
= security_inode_create(dir
, dentry
, mode
);
1392 error
= dir
->i_op
->create(dir
, dentry
, mode
, nd
);
1394 fsnotify_create(dir
, dentry
);
1398 int may_open(struct path
*path
, int acc_mode
, int flag
)
1400 struct dentry
*dentry
= path
->dentry
;
1401 struct inode
*inode
= dentry
->d_inode
;
1407 switch (inode
->i_mode
& S_IFMT
) {
1411 if (acc_mode
& MAY_WRITE
)
1416 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
1425 error
= inode_permission(inode
, acc_mode
);
1430 * An append-only file must be opened in append mode for writing.
1432 if (IS_APPEND(inode
)) {
1433 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
1439 /* O_NOATIME can only be set by the owner or superuser */
1440 if (flag
& O_NOATIME
&& !is_owner_or_cap(inode
))
1444 * Ensure there are no outstanding leases on the file.
1446 return break_lease(inode
, flag
);
1449 static int handle_truncate(struct path
*path
)
1451 struct inode
*inode
= path
->dentry
->d_inode
;
1452 int error
= get_write_access(inode
);
1456 * Refuse to truncate files with mandatory locks held on them.
1458 error
= locks_verify_locked(inode
);
1460 error
= security_path_truncate(path
);
1462 error
= do_truncate(path
->dentry
, 0,
1463 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
1466 put_write_access(inode
);
1471 * Be careful about ever adding any more callers of this
1472 * function. Its flags must be in the namei format, not
1473 * what get passed to sys_open().
1475 static int __open_namei_create(struct nameidata
*nd
, struct path
*path
,
1476 int open_flag
, int mode
)
1479 struct dentry
*dir
= nd
->path
.dentry
;
1481 if (!IS_POSIXACL(dir
->d_inode
))
1482 mode
&= ~current_umask();
1483 error
= security_path_mknod(&nd
->path
, path
->dentry
, mode
, 0);
1486 error
= vfs_create(dir
->d_inode
, path
->dentry
, mode
, nd
);
1488 mutex_unlock(&dir
->d_inode
->i_mutex
);
1489 dput(nd
->path
.dentry
);
1490 nd
->path
.dentry
= path
->dentry
;
1493 /* Don't check for write permission, don't truncate */
1494 return may_open(&nd
->path
, 0, open_flag
& ~O_TRUNC
);
1498 * Note that while the flag value (low two bits) for sys_open means:
1503 * it is changed into
1504 * 00 - no permissions needed
1505 * 01 - read-permission
1506 * 10 - write-permission
1508 * for the internal routines (ie open_namei()/follow_link() etc)
1509 * This is more logical, and also allows the 00 "no perm needed"
1510 * to be used for symlinks (where the permissions are checked
1514 static inline int open_to_namei_flags(int flag
)
1516 if ((flag
+1) & O_ACCMODE
)
1521 static int open_will_truncate(int flag
, struct inode
*inode
)
1524 * We'll never write to the fs underlying
1527 if (special_file(inode
->i_mode
))
1529 return (flag
& O_TRUNC
);
1532 static struct file
*finish_open(struct nameidata
*nd
,
1533 int open_flag
, int acc_mode
)
1539 will_truncate
= open_will_truncate(open_flag
, nd
->path
.dentry
->d_inode
);
1540 if (will_truncate
) {
1541 error
= mnt_want_write(nd
->path
.mnt
);
1545 error
= may_open(&nd
->path
, acc_mode
, open_flag
);
1548 mnt_drop_write(nd
->path
.mnt
);
1551 filp
= nameidata_to_filp(nd
);
1552 if (!IS_ERR(filp
)) {
1553 error
= ima_file_check(filp
, acc_mode
);
1556 filp
= ERR_PTR(error
);
1559 if (!IS_ERR(filp
)) {
1560 if (will_truncate
) {
1561 error
= handle_truncate(&nd
->path
);
1564 filp
= ERR_PTR(error
);
1569 * It is now safe to drop the mnt write
1570 * because the filp has had a write taken
1574 mnt_drop_write(nd
->path
.mnt
);
1575 path_put(&nd
->path
);
1579 if (!IS_ERR(nd
->intent
.open
.file
))
1580 release_open_intent(nd
);
1581 path_put(&nd
->path
);
1582 return ERR_PTR(error
);
1585 static struct file
*do_last(struct nameidata
*nd
, struct path
*path
,
1586 int open_flag
, int acc_mode
,
1587 int mode
, const char *pathname
)
1589 struct dentry
*dir
= nd
->path
.dentry
;
1591 int error
= -EISDIR
;
1593 switch (nd
->last_type
) {
1596 dir
= nd
->path
.dentry
;
1598 if (nd
->path
.mnt
->mnt_sb
->s_type
->fs_flags
& FS_REVAL_DOT
) {
1599 if (!dir
->d_op
->d_revalidate(dir
, nd
)) {
1606 if (open_flag
& O_CREAT
)
1610 audit_inode(pathname
, dir
);
1614 /* trailing slashes? */
1615 if (nd
->last
.name
[nd
->last
.len
]) {
1616 if (open_flag
& O_CREAT
)
1618 nd
->flags
|= LOOKUP_DIRECTORY
| LOOKUP_FOLLOW
;
1621 /* just plain open? */
1622 if (!(open_flag
& O_CREAT
)) {
1623 error
= do_lookup(nd
, &nd
->last
, path
);
1627 if (!path
->dentry
->d_inode
)
1629 if (path
->dentry
->d_inode
->i_op
->follow_link
)
1632 if (nd
->flags
& LOOKUP_DIRECTORY
) {
1633 if (!path
->dentry
->d_inode
->i_op
->lookup
)
1636 path_to_nameidata(path
, nd
);
1637 audit_inode(pathname
, nd
->path
.dentry
);
1641 /* OK, it's O_CREAT */
1642 mutex_lock(&dir
->d_inode
->i_mutex
);
1644 path
->dentry
= lookup_hash(nd
);
1645 path
->mnt
= nd
->path
.mnt
;
1647 error
= PTR_ERR(path
->dentry
);
1648 if (IS_ERR(path
->dentry
)) {
1649 mutex_unlock(&dir
->d_inode
->i_mutex
);
1653 if (IS_ERR(nd
->intent
.open
.file
)) {
1654 error
= PTR_ERR(nd
->intent
.open
.file
);
1655 goto exit_mutex_unlock
;
1658 /* Negative dentry, just create the file */
1659 if (!path
->dentry
->d_inode
) {
1661 * This write is needed to ensure that a
1662 * ro->rw transition does not occur between
1663 * the time when the file is created and when
1664 * a permanent write count is taken through
1665 * the 'struct file' in nameidata_to_filp().
1667 error
= mnt_want_write(nd
->path
.mnt
);
1669 goto exit_mutex_unlock
;
1670 error
= __open_namei_create(nd
, path
, open_flag
, mode
);
1672 mnt_drop_write(nd
->path
.mnt
);
1675 filp
= nameidata_to_filp(nd
);
1676 mnt_drop_write(nd
->path
.mnt
);
1677 path_put(&nd
->path
);
1678 if (!IS_ERR(filp
)) {
1679 error
= ima_file_check(filp
, acc_mode
);
1682 filp
= ERR_PTR(error
);
1689 * It already exists.
1691 mutex_unlock(&dir
->d_inode
->i_mutex
);
1692 audit_inode(pathname
, path
->dentry
);
1695 if (open_flag
& O_EXCL
)
1698 if (__follow_mount(path
)) {
1700 if (open_flag
& O_NOFOLLOW
)
1705 if (!path
->dentry
->d_inode
)
1708 if (path
->dentry
->d_inode
->i_op
->follow_link
)
1711 path_to_nameidata(path
, nd
);
1713 if (S_ISDIR(path
->dentry
->d_inode
->i_mode
))
1716 filp
= finish_open(nd
, open_flag
, acc_mode
);
1720 mutex_unlock(&dir
->d_inode
->i_mutex
);
1722 path_put_conditional(path
, nd
);
1724 if (!IS_ERR(nd
->intent
.open
.file
))
1725 release_open_intent(nd
);
1726 path_put(&nd
->path
);
1727 return ERR_PTR(error
);
1731 * Note that the low bits of the passed in "open_flag"
1732 * are not the same as in the local variable "flag". See
1733 * open_to_namei_flags() for more details.
1735 struct file
*do_filp_open(int dfd
, const char *pathname
,
1736 int open_flag
, int mode
, int acc_mode
)
1739 struct nameidata nd
;
1743 int flag
= open_to_namei_flags(open_flag
);
1744 int force_reval
= 0;
1746 if (!(open_flag
& O_CREAT
))
1749 /* Must never be set by userspace */
1750 open_flag
&= ~FMODE_NONOTIFY
;
1753 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1754 * check for O_DSYNC if the need any syncing at all we enforce it's
1755 * always set instead of having to deal with possibly weird behaviour
1756 * for malicious applications setting only __O_SYNC.
1758 if (open_flag
& __O_SYNC
)
1759 open_flag
|= O_DSYNC
;
1762 acc_mode
= MAY_OPEN
| ACC_MODE(open_flag
);
1764 /* O_TRUNC implies we need access checks for write permissions */
1765 if (open_flag
& O_TRUNC
)
1766 acc_mode
|= MAY_WRITE
;
1768 /* Allow the LSM permission hook to distinguish append
1769 access from general write access. */
1770 if (open_flag
& O_APPEND
)
1771 acc_mode
|= MAY_APPEND
;
1773 /* find the parent */
1775 error
= path_init(dfd
, pathname
, LOOKUP_PARENT
, &nd
);
1777 return ERR_PTR(error
);
1779 nd
.flags
|= LOOKUP_REVAL
;
1781 current
->total_link_count
= 0;
1782 error
= link_path_walk(pathname
, &nd
);
1784 filp
= ERR_PTR(error
);
1787 if (unlikely(!audit_dummy_context()) && (open_flag
& O_CREAT
))
1788 audit_inode(pathname
, nd
.path
.dentry
);
1791 * We have the parent and last component.
1795 filp
= get_empty_filp();
1798 nd
.intent
.open
.file
= filp
;
1799 filp
->f_flags
= open_flag
;
1800 nd
.intent
.open
.flags
= flag
;
1801 nd
.intent
.open
.create_mode
= mode
;
1802 nd
.flags
&= ~LOOKUP_PARENT
;
1803 nd
.flags
|= LOOKUP_OPEN
;
1804 if (open_flag
& O_CREAT
) {
1805 nd
.flags
|= LOOKUP_CREATE
;
1806 if (open_flag
& O_EXCL
)
1807 nd
.flags
|= LOOKUP_EXCL
;
1809 if (open_flag
& O_DIRECTORY
)
1810 nd
.flags
|= LOOKUP_DIRECTORY
;
1811 if (!(open_flag
& O_NOFOLLOW
))
1812 nd
.flags
|= LOOKUP_FOLLOW
;
1813 filp
= do_last(&nd
, &path
, open_flag
, acc_mode
, mode
, pathname
);
1814 while (unlikely(!filp
)) { /* trailing symlink */
1816 struct inode
*inode
= path
.dentry
->d_inode
;
1819 /* S_ISDIR part is a temporary automount kludge */
1820 if (!(nd
.flags
& LOOKUP_FOLLOW
) && !S_ISDIR(inode
->i_mode
))
1825 * This is subtle. Instead of calling do_follow_link() we do
1826 * the thing by hands. The reason is that this way we have zero
1827 * link_count and path_walk() (called from ->follow_link)
1828 * honoring LOOKUP_PARENT. After that we have the parent and
1829 * last component, i.e. we are in the same situation as after
1830 * the first path_walk(). Well, almost - if the last component
1831 * is normal we get its copy stored in nd->last.name and we will
1832 * have to putname() it when we are done. Procfs-like symlinks
1833 * just set LAST_BIND.
1835 nd
.flags
|= LOOKUP_PARENT
;
1836 error
= security_inode_follow_link(path
.dentry
, &nd
);
1839 error
= __do_follow_link(&path
, &nd
, &cookie
);
1840 if (unlikely(error
)) {
1841 /* nd.path had been dropped */
1842 if (!IS_ERR(cookie
) && inode
->i_op
->put_link
)
1843 inode
->i_op
->put_link(path
.dentry
, &nd
, cookie
);
1845 release_open_intent(&nd
);
1846 filp
= ERR_PTR(error
);
1850 nd
.flags
&= ~LOOKUP_PARENT
;
1851 filp
= do_last(&nd
, &path
, open_flag
, acc_mode
, mode
, pathname
);
1852 if (inode
->i_op
->put_link
)
1853 inode
->i_op
->put_link(holder
.dentry
, &nd
, cookie
);
1859 if (filp
== ERR_PTR(-ESTALE
) && !force_reval
) {
1866 path_put_conditional(&path
, &nd
);
1867 if (!IS_ERR(nd
.intent
.open
.file
))
1868 release_open_intent(&nd
);
1871 filp
= ERR_PTR(error
);
1876 * filp_open - open file and return file pointer
1878 * @filename: path to open
1879 * @flags: open flags as per the open(2) second argument
1880 * @mode: mode for the new file if O_CREAT is set, else ignored
1882 * This is the helper to open a file from kernelspace if you really
1883 * have to. But in generally you should not do this, so please move
1884 * along, nothing to see here..
1886 struct file
*filp_open(const char *filename
, int flags
, int mode
)
1888 return do_filp_open(AT_FDCWD
, filename
, flags
, mode
, 0);
1890 EXPORT_SYMBOL(filp_open
);
1893 * lookup_create - lookup a dentry, creating it if it doesn't exist
1894 * @nd: nameidata info
1895 * @is_dir: directory flag
1897 * Simple function to lookup and return a dentry and create it
1898 * if it doesn't exist. Is SMP-safe.
1900 * Returns with nd->path.dentry->d_inode->i_mutex locked.
1902 struct dentry
*lookup_create(struct nameidata
*nd
, int is_dir
)
1904 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
1906 mutex_lock_nested(&nd
->path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1908 * Yucky last component or no last component at all?
1909 * (foo/., foo/.., /////)
1911 if (nd
->last_type
!= LAST_NORM
)
1913 nd
->flags
&= ~LOOKUP_PARENT
;
1914 nd
->flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
1915 nd
->intent
.open
.flags
= O_EXCL
;
1918 * Do the final lookup.
1920 dentry
= lookup_hash(nd
);
1924 if (dentry
->d_inode
)
1927 * Special case - lookup gave negative, but... we had foo/bar/
1928 * From the vfs_mknod() POV we just have a negative dentry -
1929 * all is fine. Let's be bastards - you had / on the end, you've
1930 * been asking for (non-existent) directory. -ENOENT for you.
1932 if (unlikely(!is_dir
&& nd
->last
.name
[nd
->last
.len
])) {
1934 dentry
= ERR_PTR(-ENOENT
);
1939 dentry
= ERR_PTR(-EEXIST
);
1943 EXPORT_SYMBOL_GPL(lookup_create
);
1945 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1947 int error
= may_create(dir
, dentry
);
1952 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
1955 if (!dir
->i_op
->mknod
)
1958 error
= devcgroup_inode_mknod(mode
, dev
);
1962 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
1966 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
1968 fsnotify_create(dir
, dentry
);
1972 static int may_mknod(mode_t mode
)
1974 switch (mode
& S_IFMT
) {
1980 case 0: /* zero mode translates to S_IFREG */
1989 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, int, mode
,
1994 struct dentry
*dentry
;
1995 struct nameidata nd
;
2000 error
= user_path_parent(dfd
, filename
, &nd
, &tmp
);
2004 dentry
= lookup_create(&nd
, 0);
2005 if (IS_ERR(dentry
)) {
2006 error
= PTR_ERR(dentry
);
2009 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2010 mode
&= ~current_umask();
2011 error
= may_mknod(mode
);
2014 error
= mnt_want_write(nd
.path
.mnt
);
2017 error
= security_path_mknod(&nd
.path
, dentry
, mode
, dev
);
2019 goto out_drop_write
;
2020 switch (mode
& S_IFMT
) {
2021 case 0: case S_IFREG
:
2022 error
= vfs_create(nd
.path
.dentry
->d_inode
,dentry
,mode
,&nd
);
2024 case S_IFCHR
: case S_IFBLK
:
2025 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,
2026 new_decode_dev(dev
));
2028 case S_IFIFO
: case S_IFSOCK
:
2029 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,0);
2033 mnt_drop_write(nd
.path
.mnt
);
2037 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2044 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, int, mode
, unsigned, dev
)
2046 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
2049 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
2051 int error
= may_create(dir
, dentry
);
2056 if (!dir
->i_op
->mkdir
)
2059 mode
&= (S_IRWXUGO
|S_ISVTX
);
2060 error
= security_inode_mkdir(dir
, dentry
, mode
);
2064 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
2066 fsnotify_mkdir(dir
, dentry
);
2070 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, int, mode
)
2074 struct dentry
*dentry
;
2075 struct nameidata nd
;
2077 error
= user_path_parent(dfd
, pathname
, &nd
, &tmp
);
2081 dentry
= lookup_create(&nd
, 1);
2082 error
= PTR_ERR(dentry
);
2086 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2087 mode
&= ~current_umask();
2088 error
= mnt_want_write(nd
.path
.mnt
);
2091 error
= security_path_mkdir(&nd
.path
, dentry
, mode
);
2093 goto out_drop_write
;
2094 error
= vfs_mkdir(nd
.path
.dentry
->d_inode
, dentry
, mode
);
2096 mnt_drop_write(nd
.path
.mnt
);
2100 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2107 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, int, mode
)
2109 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
2113 * We try to drop the dentry early: we should have
2114 * a usage count of 2 if we're the only user of this
2115 * dentry, and if that is true (possibly after pruning
2116 * the dcache), then we drop the dentry now.
2118 * A low-level filesystem can, if it choses, legally
2121 * if (!d_unhashed(dentry))
2124 * if it cannot handle the case of removing a directory
2125 * that is still in use by something else..
2127 void dentry_unhash(struct dentry
*dentry
)
2130 shrink_dcache_parent(dentry
);
2131 spin_lock(&dentry
->d_lock
);
2132 if (dentry
->d_count
== 2)
2134 spin_unlock(&dentry
->d_lock
);
2137 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2139 int error
= may_delete(dir
, dentry
, 1);
2144 if (!dir
->i_op
->rmdir
)
2147 mutex_lock(&dentry
->d_inode
->i_mutex
);
2148 dentry_unhash(dentry
);
2149 if (d_mountpoint(dentry
))
2152 error
= security_inode_rmdir(dir
, dentry
);
2154 error
= dir
->i_op
->rmdir(dir
, dentry
);
2156 dentry
->d_inode
->i_flags
|= S_DEAD
;
2161 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2170 static long do_rmdir(int dfd
, const char __user
*pathname
)
2174 struct dentry
*dentry
;
2175 struct nameidata nd
;
2177 error
= user_path_parent(dfd
, pathname
, &nd
, &name
);
2181 switch(nd
.last_type
) {
2193 nd
.flags
&= ~LOOKUP_PARENT
;
2195 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2196 dentry
= lookup_hash(&nd
);
2197 error
= PTR_ERR(dentry
);
2200 error
= mnt_want_write(nd
.path
.mnt
);
2203 error
= security_path_rmdir(&nd
.path
, dentry
);
2206 error
= vfs_rmdir(nd
.path
.dentry
->d_inode
, dentry
);
2208 mnt_drop_write(nd
.path
.mnt
);
2212 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2219 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
2221 return do_rmdir(AT_FDCWD
, pathname
);
2224 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
)
2226 int error
= may_delete(dir
, dentry
, 0);
2231 if (!dir
->i_op
->unlink
)
2234 mutex_lock(&dentry
->d_inode
->i_mutex
);
2235 if (d_mountpoint(dentry
))
2238 error
= security_inode_unlink(dir
, dentry
);
2240 error
= dir
->i_op
->unlink(dir
, dentry
);
2245 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2247 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2248 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
2249 fsnotify_link_count(dentry
->d_inode
);
2257 * Make sure that the actual truncation of the file will occur outside its
2258 * directory's i_mutex. Truncate can take a long time if there is a lot of
2259 * writeout happening, and we don't want to prevent access to the directory
2260 * while waiting on the I/O.
2262 static long do_unlinkat(int dfd
, const char __user
*pathname
)
2266 struct dentry
*dentry
;
2267 struct nameidata nd
;
2268 struct inode
*inode
= NULL
;
2270 error
= user_path_parent(dfd
, pathname
, &nd
, &name
);
2275 if (nd
.last_type
!= LAST_NORM
)
2278 nd
.flags
&= ~LOOKUP_PARENT
;
2280 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2281 dentry
= lookup_hash(&nd
);
2282 error
= PTR_ERR(dentry
);
2283 if (!IS_ERR(dentry
)) {
2284 /* Why not before? Because we want correct error value */
2285 if (nd
.last
.name
[nd
.last
.len
])
2287 inode
= dentry
->d_inode
;
2290 error
= mnt_want_write(nd
.path
.mnt
);
2293 error
= security_path_unlink(&nd
.path
, dentry
);
2296 error
= vfs_unlink(nd
.path
.dentry
->d_inode
, dentry
);
2298 mnt_drop_write(nd
.path
.mnt
);
2302 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2304 iput(inode
); /* truncate the inode here */
2311 error
= !dentry
->d_inode
? -ENOENT
:
2312 S_ISDIR(dentry
->d_inode
->i_mode
) ? -EISDIR
: -ENOTDIR
;
2316 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
2318 if ((flag
& ~AT_REMOVEDIR
) != 0)
2321 if (flag
& AT_REMOVEDIR
)
2322 return do_rmdir(dfd
, pathname
);
2324 return do_unlinkat(dfd
, pathname
);
2327 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
2329 return do_unlinkat(AT_FDCWD
, pathname
);
2332 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
2334 int error
= may_create(dir
, dentry
);
2339 if (!dir
->i_op
->symlink
)
2342 error
= security_inode_symlink(dir
, dentry
, oldname
);
2346 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
2348 fsnotify_create(dir
, dentry
);
2352 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
2353 int, newdfd
, const char __user
*, newname
)
2358 struct dentry
*dentry
;
2359 struct nameidata nd
;
2361 from
= getname(oldname
);
2363 return PTR_ERR(from
);
2365 error
= user_path_parent(newdfd
, newname
, &nd
, &to
);
2369 dentry
= lookup_create(&nd
, 0);
2370 error
= PTR_ERR(dentry
);
2374 error
= mnt_want_write(nd
.path
.mnt
);
2377 error
= security_path_symlink(&nd
.path
, dentry
, from
);
2379 goto out_drop_write
;
2380 error
= vfs_symlink(nd
.path
.dentry
->d_inode
, dentry
, from
);
2382 mnt_drop_write(nd
.path
.mnt
);
2386 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2394 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
2396 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
2399 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
)
2401 struct inode
*inode
= old_dentry
->d_inode
;
2407 error
= may_create(dir
, new_dentry
);
2411 if (dir
->i_sb
!= inode
->i_sb
)
2415 * A link to an append-only or immutable file cannot be created.
2417 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
2419 if (!dir
->i_op
->link
)
2421 if (S_ISDIR(inode
->i_mode
))
2424 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
2428 mutex_lock(&inode
->i_mutex
);
2429 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
2430 mutex_unlock(&inode
->i_mutex
);
2432 fsnotify_link(dir
, inode
, new_dentry
);
2437 * Hardlinks are often used in delicate situations. We avoid
2438 * security-related surprises by not following symlinks on the
2441 * We don't follow them on the oldname either to be compatible
2442 * with linux 2.0, and to avoid hard-linking to directories
2443 * and other special files. --ADM
2445 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
2446 int, newdfd
, const char __user
*, newname
, int, flags
)
2448 struct dentry
*new_dentry
;
2449 struct nameidata nd
;
2450 struct path old_path
;
2454 if ((flags
& ~AT_SYMLINK_FOLLOW
) != 0)
2457 error
= user_path_at(olddfd
, oldname
,
2458 flags
& AT_SYMLINK_FOLLOW
? LOOKUP_FOLLOW
: 0,
2463 error
= user_path_parent(newdfd
, newname
, &nd
, &to
);
2467 if (old_path
.mnt
!= nd
.path
.mnt
)
2469 new_dentry
= lookup_create(&nd
, 0);
2470 error
= PTR_ERR(new_dentry
);
2471 if (IS_ERR(new_dentry
))
2473 error
= mnt_want_write(nd
.path
.mnt
);
2476 error
= security_path_link(old_path
.dentry
, &nd
.path
, new_dentry
);
2478 goto out_drop_write
;
2479 error
= vfs_link(old_path
.dentry
, nd
.path
.dentry
->d_inode
, new_dentry
);
2481 mnt_drop_write(nd
.path
.mnt
);
2485 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2490 path_put(&old_path
);
2495 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
2497 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
2501 * The worst of all namespace operations - renaming directory. "Perverted"
2502 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2504 * a) we can get into loop creation. Check is done in is_subdir().
2505 * b) race potential - two innocent renames can create a loop together.
2506 * That's where 4.4 screws up. Current fix: serialization on
2507 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2509 * c) we have to lock _three_ objects - parents and victim (if it exists).
2510 * And that - after we got ->i_mutex on parents (until then we don't know
2511 * whether the target exists). Solution: try to be smart with locking
2512 * order for inodes. We rely on the fact that tree topology may change
2513 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2514 * move will be locked. Thus we can rank directories by the tree
2515 * (ancestors first) and rank all non-directories after them.
2516 * That works since everybody except rename does "lock parent, lookup,
2517 * lock child" and rename is under ->s_vfs_rename_mutex.
2518 * HOWEVER, it relies on the assumption that any object with ->lookup()
2519 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2520 * we'd better make sure that there's no link(2) for them.
2521 * d) some filesystems don't support opened-but-unlinked directories,
2522 * either because of layout or because they are not ready to deal with
2523 * all cases correctly. The latter will be fixed (taking this sort of
2524 * stuff into VFS), but the former is not going away. Solution: the same
2525 * trick as in rmdir().
2526 * e) conversion from fhandle to dentry may come in the wrong moment - when
2527 * we are removing the target. Solution: we will have to grab ->i_mutex
2528 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2529 * ->i_mutex on parents, which works but leads to some truly excessive
2532 static int vfs_rename_dir(struct inode
*old_dir
, struct dentry
*old_dentry
,
2533 struct inode
*new_dir
, struct dentry
*new_dentry
)
2536 struct inode
*target
;
2539 * If we are going to change the parent - check write permissions,
2540 * we'll need to flip '..'.
2542 if (new_dir
!= old_dir
) {
2543 error
= inode_permission(old_dentry
->d_inode
, MAY_WRITE
);
2548 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2552 target
= new_dentry
->d_inode
;
2554 mutex_lock(&target
->i_mutex
);
2555 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2559 dentry_unhash(new_dentry
);
2560 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2564 target
->i_flags
|= S_DEAD
;
2565 dont_mount(new_dentry
);
2567 mutex_unlock(&target
->i_mutex
);
2568 if (d_unhashed(new_dentry
))
2569 d_rehash(new_dentry
);
2573 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2574 d_move(old_dentry
,new_dentry
);
2578 static int vfs_rename_other(struct inode
*old_dir
, struct dentry
*old_dentry
,
2579 struct inode
*new_dir
, struct dentry
*new_dentry
)
2581 struct inode
*target
;
2584 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2589 target
= new_dentry
->d_inode
;
2591 mutex_lock(&target
->i_mutex
);
2592 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2595 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2598 dont_mount(new_dentry
);
2599 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2600 d_move(old_dentry
, new_dentry
);
2603 mutex_unlock(&target
->i_mutex
);
2608 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2609 struct inode
*new_dir
, struct dentry
*new_dentry
)
2612 int is_dir
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
2613 const unsigned char *old_name
;
2615 if (old_dentry
->d_inode
== new_dentry
->d_inode
)
2618 error
= may_delete(old_dir
, old_dentry
, is_dir
);
2622 if (!new_dentry
->d_inode
)
2623 error
= may_create(new_dir
, new_dentry
);
2625 error
= may_delete(new_dir
, new_dentry
, is_dir
);
2629 if (!old_dir
->i_op
->rename
)
2632 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
2635 error
= vfs_rename_dir(old_dir
,old_dentry
,new_dir
,new_dentry
);
2637 error
= vfs_rename_other(old_dir
,old_dentry
,new_dir
,new_dentry
);
2639 fsnotify_move(old_dir
, new_dir
, old_name
, is_dir
,
2640 new_dentry
->d_inode
, old_dentry
);
2641 fsnotify_oldname_free(old_name
);
2646 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
2647 int, newdfd
, const char __user
*, newname
)
2649 struct dentry
*old_dir
, *new_dir
;
2650 struct dentry
*old_dentry
, *new_dentry
;
2651 struct dentry
*trap
;
2652 struct nameidata oldnd
, newnd
;
2657 error
= user_path_parent(olddfd
, oldname
, &oldnd
, &from
);
2661 error
= user_path_parent(newdfd
, newname
, &newnd
, &to
);
2666 if (oldnd
.path
.mnt
!= newnd
.path
.mnt
)
2669 old_dir
= oldnd
.path
.dentry
;
2671 if (oldnd
.last_type
!= LAST_NORM
)
2674 new_dir
= newnd
.path
.dentry
;
2675 if (newnd
.last_type
!= LAST_NORM
)
2678 oldnd
.flags
&= ~LOOKUP_PARENT
;
2679 newnd
.flags
&= ~LOOKUP_PARENT
;
2680 newnd
.flags
|= LOOKUP_RENAME_TARGET
;
2682 trap
= lock_rename(new_dir
, old_dir
);
2684 old_dentry
= lookup_hash(&oldnd
);
2685 error
= PTR_ERR(old_dentry
);
2686 if (IS_ERR(old_dentry
))
2688 /* source must exist */
2690 if (!old_dentry
->d_inode
)
2692 /* unless the source is a directory trailing slashes give -ENOTDIR */
2693 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
)) {
2695 if (oldnd
.last
.name
[oldnd
.last
.len
])
2697 if (newnd
.last
.name
[newnd
.last
.len
])
2700 /* source should not be ancestor of target */
2702 if (old_dentry
== trap
)
2704 new_dentry
= lookup_hash(&newnd
);
2705 error
= PTR_ERR(new_dentry
);
2706 if (IS_ERR(new_dentry
))
2708 /* target should not be an ancestor of source */
2710 if (new_dentry
== trap
)
2713 error
= mnt_want_write(oldnd
.path
.mnt
);
2716 error
= security_path_rename(&oldnd
.path
, old_dentry
,
2717 &newnd
.path
, new_dentry
);
2720 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
2721 new_dir
->d_inode
, new_dentry
);
2723 mnt_drop_write(oldnd
.path
.mnt
);
2729 unlock_rename(new_dir
, old_dir
);
2731 path_put(&newnd
.path
);
2734 path_put(&oldnd
.path
);
2740 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
2742 return sys_renameat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
);
2745 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
, const char *link
)
2749 len
= PTR_ERR(link
);
2754 if (len
> (unsigned) buflen
)
2756 if (copy_to_user(buffer
, link
, len
))
2763 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2764 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2765 * using) it for any given inode is up to filesystem.
2767 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2769 struct nameidata nd
;
2774 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
2776 return PTR_ERR(cookie
);
2778 res
= vfs_readlink(dentry
, buffer
, buflen
, nd_get_link(&nd
));
2779 if (dentry
->d_inode
->i_op
->put_link
)
2780 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
2784 int vfs_follow_link(struct nameidata
*nd
, const char *link
)
2786 return __vfs_follow_link(nd
, link
);
2789 /* get the link contents into pagecache */
2790 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
2794 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
2795 page
= read_mapping_page(mapping
, 0, NULL
);
2800 nd_terminate_link(kaddr
, dentry
->d_inode
->i_size
, PAGE_SIZE
- 1);
2804 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2806 struct page
*page
= NULL
;
2807 char *s
= page_getlink(dentry
, &page
);
2808 int res
= vfs_readlink(dentry
,buffer
,buflen
,s
);
2811 page_cache_release(page
);
2816 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
2818 struct page
*page
= NULL
;
2819 nd_set_link(nd
, page_getlink(dentry
, &page
));
2823 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2825 struct page
*page
= cookie
;
2829 page_cache_release(page
);
2834 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
2836 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
2838 struct address_space
*mapping
= inode
->i_mapping
;
2843 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
2845 flags
|= AOP_FLAG_NOFS
;
2848 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
2849 flags
, &page
, &fsdata
);
2853 kaddr
= kmap_atomic(page
, KM_USER0
);
2854 memcpy(kaddr
, symname
, len
-1);
2855 kunmap_atomic(kaddr
, KM_USER0
);
2857 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
2864 mark_inode_dirty(inode
);
2870 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
2872 return __page_symlink(inode
, symname
, len
,
2873 !(mapping_gfp_mask(inode
->i_mapping
) & __GFP_FS
));
2876 const struct inode_operations page_symlink_inode_operations
= {
2877 .readlink
= generic_readlink
,
2878 .follow_link
= page_follow_link_light
,
2879 .put_link
= page_put_link
,
2882 EXPORT_SYMBOL(user_path_at
);
2883 EXPORT_SYMBOL(follow_down
);
2884 EXPORT_SYMBOL(follow_up
);
2885 EXPORT_SYMBOL(get_write_access
); /* binfmt_aout */
2886 EXPORT_SYMBOL(getname
);
2887 EXPORT_SYMBOL(lock_rename
);
2888 EXPORT_SYMBOL(lookup_one_len
);
2889 EXPORT_SYMBOL(page_follow_link_light
);
2890 EXPORT_SYMBOL(page_put_link
);
2891 EXPORT_SYMBOL(page_readlink
);
2892 EXPORT_SYMBOL(__page_symlink
);
2893 EXPORT_SYMBOL(page_symlink
);
2894 EXPORT_SYMBOL(page_symlink_inode_operations
);
2895 EXPORT_SYMBOL(path_lookup
);
2896 EXPORT_SYMBOL(kern_path
);
2897 EXPORT_SYMBOL(vfs_path_lookup
);
2898 EXPORT_SYMBOL(inode_permission
);
2899 EXPORT_SYMBOL(file_permission
);
2900 EXPORT_SYMBOL(unlock_rename
);
2901 EXPORT_SYMBOL(vfs_create
);
2902 EXPORT_SYMBOL(vfs_follow_link
);
2903 EXPORT_SYMBOL(vfs_link
);
2904 EXPORT_SYMBOL(vfs_mkdir
);
2905 EXPORT_SYMBOL(vfs_mknod
);
2906 EXPORT_SYMBOL(generic_permission
);
2907 EXPORT_SYMBOL(vfs_readlink
);
2908 EXPORT_SYMBOL(vfs_rename
);
2909 EXPORT_SYMBOL(vfs_rmdir
);
2910 EXPORT_SYMBOL(vfs_symlink
);
2911 EXPORT_SYMBOL(vfs_unlink
);
2912 EXPORT_SYMBOL(dentry_unhash
);
2913 EXPORT_SYMBOL(generic_readlink
);