4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * Some corrections by tytso.
11 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
14 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
21 #include <linux/namei.h>
22 #include <linux/quotaops.h>
23 #include <linux/pagemap.h>
24 #include <linux/fsnotify.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/ima.h>
28 #include <linux/syscalls.h>
29 #include <linux/mount.h>
30 #include <linux/audit.h>
31 #include <linux/capability.h>
32 #include <linux/file.h>
33 #include <linux/fcntl.h>
34 #include <linux/device_cgroup.h>
35 #include <linux/fs_struct.h>
36 #include <asm/uaccess.h>
38 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
40 /* [Feb-1997 T. Schoebel-Theuer]
41 * Fundamental changes in the pathname lookup mechanisms (namei)
42 * were necessary because of omirr. The reason is that omirr needs
43 * to know the _real_ pathname, not the user-supplied one, in case
44 * of symlinks (and also when transname replacements occur).
46 * The new code replaces the old recursive symlink resolution with
47 * an iterative one (in case of non-nested symlink chains). It does
48 * this with calls to <fs>_follow_link().
49 * As a side effect, dir_namei(), _namei() and follow_link() are now
50 * replaced with a single function lookup_dentry() that can handle all
51 * the special cases of the former code.
53 * With the new dcache, the pathname is stored at each inode, at least as
54 * long as the refcount of the inode is positive. As a side effect, the
55 * size of the dcache depends on the inode cache and thus is dynamic.
57 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
58 * resolution to correspond with current state of the code.
60 * Note that the symlink resolution is not *completely* iterative.
61 * There is still a significant amount of tail- and mid- recursion in
62 * the algorithm. Also, note that <fs>_readlink() is not used in
63 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
64 * may return different results than <fs>_follow_link(). Many virtual
65 * filesystems (including /proc) exhibit this behavior.
68 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
69 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
70 * and the name already exists in form of a symlink, try to create the new
71 * name indicated by the symlink. The old code always complained that the
72 * name already exists, due to not following the symlink even if its target
73 * is nonexistent. The new semantics affects also mknod() and link() when
74 * the name is a symlink pointing to a non-existant name.
76 * I don't know which semantics is the right one, since I have no access
77 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
78 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
79 * "old" one. Personally, I think the new semantics is much more logical.
80 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
81 * file does succeed in both HP-UX and SunOs, but not in Solaris
82 * and in the old Linux semantics.
85 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
86 * semantics. See the comments in "open_namei" and "do_link" below.
88 * [10-Sep-98 Alan Modra] Another symlink change.
91 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
92 * inside the path - always follow.
93 * in the last component in creation/removal/renaming - never follow.
94 * if LOOKUP_FOLLOW passed - follow.
95 * if the pathname has trailing slashes - follow.
96 * otherwise - don't follow.
97 * (applied in that order).
99 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
100 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
101 * During the 2.4 we need to fix the userland stuff depending on it -
102 * hopefully we will be able to get rid of that wart in 2.5. So far only
103 * XEmacs seems to be relying on it...
106 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
107 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
108 * any extra contention...
111 /* 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
);
171 * This does basic POSIX ACL permission checking
173 static int acl_permission_check(struct inode
*inode
, int mask
,
174 int (*check_acl
)(struct inode
*inode
, int mask
))
176 umode_t mode
= inode
->i_mode
;
178 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
180 if (current_fsuid() == inode
->i_uid
)
183 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
) && check_acl
) {
184 int error
= check_acl(inode
, mask
);
185 if (error
!= -EAGAIN
)
189 if (in_group_p(inode
->i_gid
))
194 * If the DACs are ok we don't need any capability check.
196 if ((mask
& ~mode
) == 0)
202 * generic_permission - check for access rights on a Posix-like filesystem
203 * @inode: inode to check access rights for
204 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
205 * @check_acl: optional callback to check for Posix ACLs
207 * Used to check for read/write/execute permissions on a file.
208 * We use "fsuid" for this, letting us set arbitrary permissions
209 * for filesystem access without changing the "normal" uids which
210 * are used for other things..
212 int generic_permission(struct inode
*inode
, int mask
,
213 int (*check_acl
)(struct inode
*inode
, int mask
))
218 * Do the basic POSIX ACL permission checks.
220 ret
= acl_permission_check(inode
, mask
, check_acl
);
225 * Read/write DACs are always overridable.
226 * Executable DACs are overridable if at least one exec bit is set.
228 if (!(mask
& MAY_EXEC
) || execute_ok(inode
))
229 if (capable(CAP_DAC_OVERRIDE
))
233 * Searching includes executable on directories, else just read.
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
,
286 mask
& (MAY_READ
|MAY_WRITE
|MAY_EXEC
|MAY_APPEND
));
290 * file_permission - check for additional access rights to a given file
291 * @file: file to check access rights for
292 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
294 * Used to check for read/write/execute permissions on an already opened
298 * Do not use this function in new code. All access checks should
299 * be done using inode_permission().
301 int file_permission(struct file
*file
, int mask
)
303 return inode_permission(file
->f_path
.dentry
->d_inode
, mask
);
307 * get_write_access() gets write permission for a file.
308 * put_write_access() releases this write permission.
309 * This is used for regular files.
310 * We cannot support write (and maybe mmap read-write shared) accesses and
311 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
312 * can have the following values:
313 * 0: no writers, no VM_DENYWRITE mappings
314 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
315 * > 0: (i_writecount) users are writing to the file.
317 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
318 * except for the cases where we don't hold i_writecount yet. Then we need to
319 * use {get,deny}_write_access() - these functions check the sign and refuse
320 * to do the change if sign is wrong. Exclusion between them is provided by
321 * the inode->i_lock spinlock.
324 int get_write_access(struct inode
* inode
)
326 spin_lock(&inode
->i_lock
);
327 if (atomic_read(&inode
->i_writecount
) < 0) {
328 spin_unlock(&inode
->i_lock
);
331 atomic_inc(&inode
->i_writecount
);
332 spin_unlock(&inode
->i_lock
);
337 int deny_write_access(struct file
* file
)
339 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
341 spin_lock(&inode
->i_lock
);
342 if (atomic_read(&inode
->i_writecount
) > 0) {
343 spin_unlock(&inode
->i_lock
);
346 atomic_dec(&inode
->i_writecount
);
347 spin_unlock(&inode
->i_lock
);
353 * path_get - get a reference to a path
354 * @path: path to get the reference to
356 * Given a path increment the reference count to the dentry and the vfsmount.
358 void path_get(struct path
*path
)
363 EXPORT_SYMBOL(path_get
);
366 * path_put - put a reference to a path
367 * @path: path to put the reference to
369 * Given a path decrement the reference count to the dentry and the vfsmount.
371 void path_put(struct path
*path
)
376 EXPORT_SYMBOL(path_put
);
379 * release_open_intent - free up open intent resources
380 * @nd: pointer to nameidata
382 void release_open_intent(struct nameidata
*nd
)
384 if (nd
->intent
.open
.file
->f_path
.dentry
== NULL
)
385 put_filp(nd
->intent
.open
.file
);
387 fput(nd
->intent
.open
.file
);
390 static inline struct dentry
*
391 do_revalidate(struct dentry
*dentry
, struct nameidata
*nd
)
393 int status
= dentry
->d_op
->d_revalidate(dentry
, nd
);
394 if (unlikely(status
<= 0)) {
396 * The dentry failed validation.
397 * If d_revalidate returned 0 attempt to invalidate
398 * the dentry otherwise d_revalidate is asking us
399 * to return a fail status.
402 if (!d_invalidate(dentry
)) {
408 dentry
= ERR_PTR(status
);
415 * Internal lookup() using the new generic dcache.
418 static struct dentry
* cached_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
420 struct dentry
* dentry
= __d_lookup(parent
, name
);
422 /* lockess __d_lookup may fail due to concurrent d_move()
423 * in some unrelated directory, so try with d_lookup
426 dentry
= d_lookup(parent
, name
);
428 if (dentry
&& dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
429 dentry
= do_revalidate(dentry
, nd
);
435 * Short-cut version of permission(), for calling by
436 * path_walk(), when dcache lock is held. Combines parts
437 * of permission() and generic_permission(), and tests ONLY for
438 * MAY_EXEC permission.
440 * If appropriate, check DAC only. If not appropriate, or
441 * short-cut DAC fails, then call permission() to do more
442 * complete permission check.
444 static int exec_permission_lite(struct inode
*inode
)
448 if (inode
->i_op
->permission
) {
449 ret
= inode
->i_op
->permission(inode
, MAY_EXEC
);
454 ret
= acl_permission_check(inode
, MAY_EXEC
, inode
->i_op
->check_acl
);
458 if (capable(CAP_DAC_OVERRIDE
) || capable(CAP_DAC_READ_SEARCH
))
463 return security_inode_permission(inode
, MAY_EXEC
);
467 * This is called when everything else fails, and we actually have
468 * to go to the low-level filesystem to find out what we should do..
470 * We get the directory semaphore, and after getting that we also
471 * make sure that nobody added the entry to the dcache in the meantime..
474 static struct dentry
* real_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
476 struct dentry
* result
;
477 struct inode
*dir
= parent
->d_inode
;
479 mutex_lock(&dir
->i_mutex
);
481 * First re-do the cached lookup just in case it was created
482 * while we waited for the directory semaphore..
484 * FIXME! This could use version numbering or similar to
485 * avoid unnecessary cache lookups.
487 * The "dcache_lock" is purely to protect the RCU list walker
488 * from concurrent renames at this point (we mustn't get false
489 * negatives from the RCU list walk here, unlike the optimistic
492 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
494 result
= d_lookup(parent
, name
);
496 struct dentry
*dentry
;
498 /* Don't create child dentry for a dead directory. */
499 result
= ERR_PTR(-ENOENT
);
503 dentry
= d_alloc(parent
, name
);
504 result
= ERR_PTR(-ENOMEM
);
506 result
= dir
->i_op
->lookup(dir
, dentry
, nd
);
513 mutex_unlock(&dir
->i_mutex
);
518 * Uhhuh! Nasty case: the cache was re-populated while
519 * we waited on the semaphore. Need to revalidate.
521 mutex_unlock(&dir
->i_mutex
);
522 if (result
->d_op
&& result
->d_op
->d_revalidate
) {
523 result
= do_revalidate(result
, nd
);
525 result
= ERR_PTR(-ENOENT
);
530 static __always_inline
void set_root(struct nameidata
*nd
)
533 struct fs_struct
*fs
= current
->fs
;
534 read_lock(&fs
->lock
);
537 read_unlock(&fs
->lock
);
541 static int link_path_walk(const char *, struct nameidata
*);
543 static __always_inline
int __vfs_follow_link(struct nameidata
*nd
, const char *link
)
557 res
= link_path_walk(link
, nd
);
558 if (nd
->depth
|| res
|| nd
->last_type
!=LAST_NORM
)
561 * If it is an iterative symlinks resolution in open_namei() we
562 * have to copy the last component. And all that crap because of
563 * bloody create() on broken symlinks. Furrfu...
566 if (unlikely(!name
)) {
570 strcpy(name
, nd
->last
.name
);
571 nd
->last
.name
= name
;
575 return PTR_ERR(link
);
578 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
581 if (path
->mnt
!= nd
->path
.mnt
)
585 static inline void path_to_nameidata(struct path
*path
, struct nameidata
*nd
)
587 dput(nd
->path
.dentry
);
588 if (nd
->path
.mnt
!= path
->mnt
)
589 mntput(nd
->path
.mnt
);
590 nd
->path
.mnt
= path
->mnt
;
591 nd
->path
.dentry
= path
->dentry
;
594 static __always_inline
int __do_follow_link(struct path
*path
, struct nameidata
*nd
)
598 struct dentry
*dentry
= path
->dentry
;
600 touch_atime(path
->mnt
, dentry
);
601 nd_set_link(nd
, NULL
);
603 if (path
->mnt
!= nd
->path
.mnt
) {
604 path_to_nameidata(path
, nd
);
608 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
609 error
= PTR_ERR(cookie
);
610 if (!IS_ERR(cookie
)) {
611 char *s
= nd_get_link(nd
);
614 error
= __vfs_follow_link(nd
, s
);
615 if (dentry
->d_inode
->i_op
->put_link
)
616 dentry
->d_inode
->i_op
->put_link(dentry
, nd
, cookie
);
622 * This limits recursive symlink follows to 8, while
623 * limiting consecutive symlinks to 40.
625 * Without that kind of total limit, nasty chains of consecutive
626 * symlinks can cause almost arbitrarily long lookups.
628 static inline int do_follow_link(struct path
*path
, struct nameidata
*nd
)
631 if (current
->link_count
>= MAX_NESTED_LINKS
)
633 if (current
->total_link_count
>= 40)
635 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
637 err
= security_inode_follow_link(path
->dentry
, nd
);
640 current
->link_count
++;
641 current
->total_link_count
++;
643 err
= __do_follow_link(path
, nd
);
645 current
->link_count
--;
649 path_put_conditional(path
, nd
);
654 int follow_up(struct path
*path
)
656 struct vfsmount
*parent
;
657 struct dentry
*mountpoint
;
658 spin_lock(&vfsmount_lock
);
659 parent
= path
->mnt
->mnt_parent
;
660 if (parent
== path
->mnt
) {
661 spin_unlock(&vfsmount_lock
);
665 mountpoint
= dget(path
->mnt
->mnt_mountpoint
);
666 spin_unlock(&vfsmount_lock
);
668 path
->dentry
= mountpoint
;
674 /* no need for dcache_lock, as serialization is taken care in
677 static int __follow_mount(struct path
*path
)
680 while (d_mountpoint(path
->dentry
)) {
681 struct vfsmount
*mounted
= lookup_mnt(path
);
688 path
->dentry
= dget(mounted
->mnt_root
);
694 static void follow_mount(struct path
*path
)
696 while (d_mountpoint(path
->dentry
)) {
697 struct vfsmount
*mounted
= lookup_mnt(path
);
703 path
->dentry
= dget(mounted
->mnt_root
);
707 /* no need for dcache_lock, as serialization is taken care in
710 int follow_down(struct path
*path
)
712 struct vfsmount
*mounted
;
714 mounted
= lookup_mnt(path
);
719 path
->dentry
= dget(mounted
->mnt_root
);
725 static __always_inline
void follow_dotdot(struct nameidata
*nd
)
730 struct vfsmount
*parent
;
731 struct dentry
*old
= nd
->path
.dentry
;
733 if (nd
->path
.dentry
== nd
->root
.dentry
&&
734 nd
->path
.mnt
== nd
->root
.mnt
) {
737 spin_lock(&dcache_lock
);
738 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
739 nd
->path
.dentry
= dget(nd
->path
.dentry
->d_parent
);
740 spin_unlock(&dcache_lock
);
744 spin_unlock(&dcache_lock
);
745 spin_lock(&vfsmount_lock
);
746 parent
= nd
->path
.mnt
->mnt_parent
;
747 if (parent
== nd
->path
.mnt
) {
748 spin_unlock(&vfsmount_lock
);
752 nd
->path
.dentry
= dget(nd
->path
.mnt
->mnt_mountpoint
);
753 spin_unlock(&vfsmount_lock
);
755 mntput(nd
->path
.mnt
);
756 nd
->path
.mnt
= parent
;
758 follow_mount(&nd
->path
);
762 * It's more convoluted than I'd like it to be, but... it's still fairly
763 * small and for now I'd prefer to have fast path as straight as possible.
764 * It _is_ time-critical.
766 static int do_lookup(struct nameidata
*nd
, struct qstr
*name
,
769 struct vfsmount
*mnt
= nd
->path
.mnt
;
770 struct dentry
*dentry
;
772 * See if the low-level filesystem might want
773 * to use its own hash..
775 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
776 int err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
, name
);
781 dentry
= __d_lookup(nd
->path
.dentry
, name
);
784 if (dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
785 goto need_revalidate
;
788 path
->dentry
= dentry
;
789 __follow_mount(path
);
793 dentry
= real_lookup(nd
->path
.dentry
, name
, nd
);
799 dentry
= do_revalidate(dentry
, nd
);
807 return PTR_ERR(dentry
);
812 * This is the basic name resolution function, turning a pathname into
813 * the final dentry. We expect 'base' to be positive and a directory.
815 * Returns 0 and nd will have valid dentry and mnt on success.
816 * Returns error and drops reference to input namei data on failure.
818 static int link_path_walk(const char *name
, struct nameidata
*nd
)
823 unsigned int lookup_flags
= nd
->flags
;
830 inode
= nd
->path
.dentry
->d_inode
;
832 lookup_flags
= LOOKUP_FOLLOW
| (nd
->flags
& LOOKUP_CONTINUE
);
834 /* At this point we know we have a real path component. */
840 nd
->flags
|= LOOKUP_CONTINUE
;
841 err
= exec_permission_lite(inode
);
846 c
= *(const unsigned char *)name
;
848 hash
= init_name_hash();
851 hash
= partial_name_hash(c
, hash
);
852 c
= *(const unsigned char *)name
;
853 } while (c
&& (c
!= '/'));
854 this.len
= name
- (const char *) this.name
;
855 this.hash
= end_name_hash(hash
);
857 /* remove trailing slashes? */
860 while (*++name
== '/');
862 goto last_with_slashes
;
865 * "." and ".." are special - ".." especially so because it has
866 * to be able to know about the current root directory and
867 * parent relationships.
869 if (this.name
[0] == '.') switch (this.len
) {
873 if (this.name
[1] != '.')
876 inode
= nd
->path
.dentry
->d_inode
;
881 /* This does the actual lookups.. */
882 err
= do_lookup(nd
, &this, &next
);
887 inode
= next
.dentry
->d_inode
;
891 if (inode
->i_op
->follow_link
) {
892 err
= do_follow_link(&next
, nd
);
896 inode
= nd
->path
.dentry
->d_inode
;
900 path_to_nameidata(&next
, nd
);
902 if (!inode
->i_op
->lookup
)
905 /* here ends the main loop */
908 lookup_flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
910 /* Clear LOOKUP_CONTINUE iff it was previously unset */
911 nd
->flags
&= lookup_flags
| ~LOOKUP_CONTINUE
;
912 if (lookup_flags
& LOOKUP_PARENT
)
914 if (this.name
[0] == '.') switch (this.len
) {
918 if (this.name
[1] != '.')
921 inode
= nd
->path
.dentry
->d_inode
;
926 err
= do_lookup(nd
, &this, &next
);
929 inode
= next
.dentry
->d_inode
;
930 if ((lookup_flags
& LOOKUP_FOLLOW
)
931 && inode
&& inode
->i_op
->follow_link
) {
932 err
= do_follow_link(&next
, nd
);
935 inode
= nd
->path
.dentry
->d_inode
;
937 path_to_nameidata(&next
, nd
);
941 if (lookup_flags
& LOOKUP_DIRECTORY
) {
943 if (!inode
->i_op
->lookup
)
949 nd
->last_type
= LAST_NORM
;
950 if (this.name
[0] != '.')
953 nd
->last_type
= LAST_DOT
;
954 else if (this.len
== 2 && this.name
[1] == '.')
955 nd
->last_type
= LAST_DOTDOT
;
960 * We bypassed the ordinary revalidation routines.
961 * We may need to check the cached dentry for staleness.
963 if (nd
->path
.dentry
&& nd
->path
.dentry
->d_sb
&&
964 (nd
->path
.dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
)) {
966 /* Note: we do not d_invalidate() */
967 if (!nd
->path
.dentry
->d_op
->d_revalidate(
968 nd
->path
.dentry
, nd
))
974 path_put_conditional(&next
, nd
);
982 static int path_walk(const char *name
, struct nameidata
*nd
)
984 struct path save
= nd
->path
;
987 current
->total_link_count
= 0;
989 /* make sure the stuff we saved doesn't go away */
992 result
= link_path_walk(name
, nd
);
993 if (result
== -ESTALE
) {
994 /* nd->path had been dropped */
995 current
->total_link_count
= 0;
998 nd
->flags
|= LOOKUP_REVAL
;
999 result
= link_path_walk(name
, nd
);
1007 static int path_init(int dfd
, const char *name
, unsigned int flags
, struct nameidata
*nd
)
1013 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1016 nd
->root
.mnt
= NULL
;
1020 nd
->path
= nd
->root
;
1021 path_get(&nd
->root
);
1022 } else if (dfd
== AT_FDCWD
) {
1023 struct fs_struct
*fs
= current
->fs
;
1024 read_lock(&fs
->lock
);
1027 read_unlock(&fs
->lock
);
1029 struct dentry
*dentry
;
1031 file
= fget_light(dfd
, &fput_needed
);
1036 dentry
= file
->f_path
.dentry
;
1039 if (!S_ISDIR(dentry
->d_inode
->i_mode
))
1042 retval
= file_permission(file
, MAY_EXEC
);
1046 nd
->path
= file
->f_path
;
1047 path_get(&file
->f_path
);
1049 fput_light(file
, fput_needed
);
1054 fput_light(file
, fput_needed
);
1059 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1060 static int do_path_lookup(int dfd
, const char *name
,
1061 unsigned int flags
, struct nameidata
*nd
)
1063 int retval
= path_init(dfd
, name
, flags
, nd
);
1065 retval
= path_walk(name
, nd
);
1066 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1067 nd
->path
.dentry
->d_inode
))
1068 audit_inode(name
, nd
->path
.dentry
);
1070 path_put(&nd
->root
);
1071 nd
->root
.mnt
= NULL
;
1076 int path_lookup(const char *name
, unsigned int flags
,
1077 struct nameidata
*nd
)
1079 return do_path_lookup(AT_FDCWD
, name
, flags
, nd
);
1082 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
1084 struct nameidata nd
;
1085 int res
= do_path_lookup(AT_FDCWD
, name
, flags
, &nd
);
1092 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1093 * @dentry: pointer to dentry of the base directory
1094 * @mnt: pointer to vfs mount of the base directory
1095 * @name: pointer to file name
1096 * @flags: lookup flags
1097 * @nd: pointer to nameidata
1099 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
1100 const char *name
, unsigned int flags
,
1101 struct nameidata
*nd
)
1105 /* same as do_path_lookup */
1106 nd
->last_type
= LAST_ROOT
;
1110 nd
->path
.dentry
= dentry
;
1112 path_get(&nd
->path
);
1113 nd
->root
= nd
->path
;
1114 path_get(&nd
->root
);
1116 retval
= path_walk(name
, nd
);
1117 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1118 nd
->path
.dentry
->d_inode
))
1119 audit_inode(name
, nd
->path
.dentry
);
1121 path_put(&nd
->root
);
1122 nd
->root
.mnt
= NULL
;
1128 * path_lookup_open - lookup a file path with open intent
1129 * @dfd: the directory to use as base, or AT_FDCWD
1130 * @name: pointer to file name
1131 * @lookup_flags: lookup intent flags
1132 * @nd: pointer to nameidata
1133 * @open_flags: open intent flags
1135 static int path_lookup_open(int dfd
, const char *name
,
1136 unsigned int lookup_flags
, struct nameidata
*nd
, int open_flags
)
1138 struct file
*filp
= get_empty_filp();
1143 nd
->intent
.open
.file
= filp
;
1144 nd
->intent
.open
.flags
= open_flags
;
1145 nd
->intent
.open
.create_mode
= 0;
1146 err
= do_path_lookup(dfd
, name
, lookup_flags
|LOOKUP_OPEN
, nd
);
1147 if (IS_ERR(nd
->intent
.open
.file
)) {
1149 err
= PTR_ERR(nd
->intent
.open
.file
);
1150 path_put(&nd
->path
);
1152 } else if (err
!= 0)
1153 release_open_intent(nd
);
1157 static struct dentry
*__lookup_hash(struct qstr
*name
,
1158 struct dentry
*base
, struct nameidata
*nd
)
1160 struct dentry
*dentry
;
1161 struct inode
*inode
;
1164 inode
= base
->d_inode
;
1167 * See if the low-level filesystem might want
1168 * to use its own hash..
1170 if (base
->d_op
&& base
->d_op
->d_hash
) {
1171 err
= base
->d_op
->d_hash(base
, name
);
1172 dentry
= ERR_PTR(err
);
1177 dentry
= cached_lookup(base
, name
, nd
);
1181 /* Don't create child dentry for a dead directory. */
1182 dentry
= ERR_PTR(-ENOENT
);
1183 if (IS_DEADDIR(inode
))
1186 new = d_alloc(base
, name
);
1187 dentry
= ERR_PTR(-ENOMEM
);
1190 dentry
= inode
->i_op
->lookup(inode
, new, nd
);
1201 * Restricted form of lookup. Doesn't follow links, single-component only,
1202 * needs parent already locked. Doesn't follow mounts.
1205 static struct dentry
*lookup_hash(struct nameidata
*nd
)
1209 err
= inode_permission(nd
->path
.dentry
->d_inode
, MAY_EXEC
);
1211 return ERR_PTR(err
);
1212 return __lookup_hash(&nd
->last
, nd
->path
.dentry
, nd
);
1215 static int __lookup_one_len(const char *name
, struct qstr
*this,
1216 struct dentry
*base
, int len
)
1226 hash
= init_name_hash();
1228 c
= *(const unsigned char *)name
++;
1229 if (c
== '/' || c
== '\0')
1231 hash
= partial_name_hash(c
, hash
);
1233 this->hash
= end_name_hash(hash
);
1238 * lookup_one_len - filesystem helper to lookup single pathname component
1239 * @name: pathname component to lookup
1240 * @base: base directory to lookup from
1241 * @len: maximum length @len should be interpreted to
1243 * Note that this routine is purely a helper for filesystem usage and should
1244 * not be called by generic code. Also note that by using this function the
1245 * nameidata argument is passed to the filesystem methods and a filesystem
1246 * using this helper needs to be prepared for that.
1248 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
1253 WARN_ON_ONCE(!mutex_is_locked(&base
->d_inode
->i_mutex
));
1255 err
= __lookup_one_len(name
, &this, base
, len
);
1257 return ERR_PTR(err
);
1259 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
1261 return ERR_PTR(err
);
1262 return __lookup_hash(&this, base
, NULL
);
1265 int user_path_at(int dfd
, const char __user
*name
, unsigned flags
,
1268 struct nameidata nd
;
1269 char *tmp
= getname(name
);
1270 int err
= PTR_ERR(tmp
);
1273 BUG_ON(flags
& LOOKUP_PARENT
);
1275 err
= do_path_lookup(dfd
, tmp
, flags
, &nd
);
1283 static int user_path_parent(int dfd
, const char __user
*path
,
1284 struct nameidata
*nd
, char **name
)
1286 char *s
= getname(path
);
1292 error
= do_path_lookup(dfd
, s
, LOOKUP_PARENT
, nd
);
1302 * It's inline, so penalty for filesystems that don't use sticky bit is
1305 static inline int check_sticky(struct inode
*dir
, struct inode
*inode
)
1307 uid_t fsuid
= current_fsuid();
1309 if (!(dir
->i_mode
& S_ISVTX
))
1311 if (inode
->i_uid
== fsuid
)
1313 if (dir
->i_uid
== fsuid
)
1315 return !capable(CAP_FOWNER
);
1319 * Check whether we can remove a link victim from directory dir, check
1320 * whether the type of victim is right.
1321 * 1. We can't do it if dir is read-only (done in permission())
1322 * 2. We should have write and exec permissions on dir
1323 * 3. We can't remove anything from append-only dir
1324 * 4. We can't do anything with immutable dir (done in permission())
1325 * 5. If the sticky bit on dir is set we should either
1326 * a. be owner of dir, or
1327 * b. be owner of victim, or
1328 * c. have CAP_FOWNER capability
1329 * 6. If the victim is append-only or immutable we can't do antyhing with
1330 * links pointing to it.
1331 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1332 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1333 * 9. We can't remove a root or mountpoint.
1334 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1335 * nfs_async_unlink().
1337 static int may_delete(struct inode
*dir
,struct dentry
*victim
,int isdir
)
1341 if (!victim
->d_inode
)
1344 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
1345 audit_inode_child(victim
->d_name
.name
, victim
, dir
);
1347 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
1352 if (check_sticky(dir
, victim
->d_inode
)||IS_APPEND(victim
->d_inode
)||
1353 IS_IMMUTABLE(victim
->d_inode
) || IS_SWAPFILE(victim
->d_inode
))
1356 if (!S_ISDIR(victim
->d_inode
->i_mode
))
1358 if (IS_ROOT(victim
))
1360 } else if (S_ISDIR(victim
->d_inode
->i_mode
))
1362 if (IS_DEADDIR(dir
))
1364 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
1369 /* Check whether we can create an object with dentry child in directory
1371 * 1. We can't do it if child already exists (open has special treatment for
1372 * this case, but since we are inlined it's OK)
1373 * 2. We can't do it if dir is read-only (done in permission())
1374 * 3. We should have write and exec permissions on dir
1375 * 4. We can't do it if dir is immutable (done in permission())
1377 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
1381 if (IS_DEADDIR(dir
))
1383 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
1387 * O_DIRECTORY translates into forcing a directory lookup.
1389 static inline int lookup_flags(unsigned int f
)
1391 unsigned long retval
= LOOKUP_FOLLOW
;
1394 retval
&= ~LOOKUP_FOLLOW
;
1396 if (f
& O_DIRECTORY
)
1397 retval
|= LOOKUP_DIRECTORY
;
1403 * p1 and p2 should be directories on the same fs.
1405 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
1410 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1414 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1416 p
= d_ancestor(p2
, p1
);
1418 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1419 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1423 p
= d_ancestor(p1
, p2
);
1425 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1426 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1430 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1431 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1435 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
1437 mutex_unlock(&p1
->d_inode
->i_mutex
);
1439 mutex_unlock(&p2
->d_inode
->i_mutex
);
1440 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1444 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1445 struct nameidata
*nd
)
1447 int error
= may_create(dir
, dentry
);
1452 if (!dir
->i_op
->create
)
1453 return -EACCES
; /* shouldn't it be ENOSYS? */
1456 error
= security_inode_create(dir
, dentry
, mode
);
1460 error
= dir
->i_op
->create(dir
, dentry
, mode
, nd
);
1462 fsnotify_create(dir
, dentry
);
1466 int may_open(struct path
*path
, int acc_mode
, int flag
)
1468 struct dentry
*dentry
= path
->dentry
;
1469 struct inode
*inode
= dentry
->d_inode
;
1475 switch (inode
->i_mode
& S_IFMT
) {
1479 if (acc_mode
& MAY_WRITE
)
1484 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
1493 error
= inode_permission(inode
, acc_mode
);
1497 error
= ima_path_check(path
, acc_mode
?
1498 acc_mode
& (MAY_READ
| MAY_WRITE
| MAY_EXEC
) :
1499 ACC_MODE(flag
) & (MAY_READ
| MAY_WRITE
),
1505 * An append-only file must be opened in append mode for writing.
1507 if (IS_APPEND(inode
)) {
1509 if ((flag
& FMODE_WRITE
) && !(flag
& O_APPEND
))
1515 /* O_NOATIME can only be set by the owner or superuser */
1516 if (flag
& O_NOATIME
)
1517 if (!is_owner_or_cap(inode
)) {
1523 * Ensure there are no outstanding leases on the file.
1525 error
= break_lease(inode
, flag
);
1529 if (flag
& O_TRUNC
) {
1530 error
= get_write_access(inode
);
1535 * Refuse to truncate files with mandatory locks held on them.
1537 error
= locks_verify_locked(inode
);
1539 error
= security_path_truncate(path
, 0,
1540 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
);
1544 error
= do_truncate(dentry
, 0,
1545 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
1548 put_write_access(inode
);
1552 if (flag
& FMODE_WRITE
)
1557 ima_counts_put(path
, acc_mode
?
1558 acc_mode
& (MAY_READ
| MAY_WRITE
| MAY_EXEC
) :
1559 ACC_MODE(flag
) & (MAY_READ
| MAY_WRITE
));
1564 * Be careful about ever adding any more callers of this
1565 * function. Its flags must be in the namei format, not
1566 * what get passed to sys_open().
1568 static int __open_namei_create(struct nameidata
*nd
, struct path
*path
,
1572 struct dentry
*dir
= nd
->path
.dentry
;
1574 if (!IS_POSIXACL(dir
->d_inode
))
1575 mode
&= ~current_umask();
1576 error
= security_path_mknod(&nd
->path
, path
->dentry
, mode
, 0);
1579 error
= vfs_create(dir
->d_inode
, path
->dentry
, mode
, nd
);
1581 mutex_unlock(&dir
->d_inode
->i_mutex
);
1582 dput(nd
->path
.dentry
);
1583 nd
->path
.dentry
= path
->dentry
;
1586 /* Don't check for write permission, don't truncate */
1587 return may_open(&nd
->path
, 0, flag
& ~O_TRUNC
);
1591 * Note that while the flag value (low two bits) for sys_open means:
1596 * it is changed into
1597 * 00 - no permissions needed
1598 * 01 - read-permission
1599 * 10 - write-permission
1601 * for the internal routines (ie open_namei()/follow_link() etc)
1602 * This is more logical, and also allows the 00 "no perm needed"
1603 * to be used for symlinks (where the permissions are checked
1607 static inline int open_to_namei_flags(int flag
)
1609 if ((flag
+1) & O_ACCMODE
)
1614 static int open_will_write_to_fs(int flag
, struct inode
*inode
)
1617 * We'll never write to the fs underlying
1620 if (special_file(inode
->i_mode
))
1622 return (flag
& O_TRUNC
);
1626 * Note that the low bits of the passed in "open_flag"
1627 * are not the same as in the local variable "flag". See
1628 * open_to_namei_flags() for more details.
1630 struct file
*do_filp_open(int dfd
, const char *pathname
,
1631 int open_flag
, int mode
, int acc_mode
)
1634 struct nameidata nd
;
1636 struct path path
, save
;
1640 int flag
= open_to_namei_flags(open_flag
);
1643 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1644 * check for O_DSYNC if the need any syncing at all we enforce it's
1645 * always set instead of having to deal with possibly weird behaviour
1646 * for malicious applications setting only __O_SYNC.
1648 if (open_flag
& __O_SYNC
)
1649 open_flag
|= O_DSYNC
;
1652 acc_mode
= MAY_OPEN
| ACC_MODE(flag
);
1654 /* O_TRUNC implies we need access checks for write permissions */
1656 acc_mode
|= MAY_WRITE
;
1658 /* Allow the LSM permission hook to distinguish append
1659 access from general write access. */
1660 if (flag
& O_APPEND
)
1661 acc_mode
|= MAY_APPEND
;
1664 * The simplest case - just a plain lookup.
1666 if (!(flag
& O_CREAT
)) {
1667 error
= path_lookup_open(dfd
, pathname
, lookup_flags(flag
),
1670 return ERR_PTR(error
);
1675 * Create - we need to know the parent.
1677 error
= path_init(dfd
, pathname
, LOOKUP_PARENT
, &nd
);
1679 return ERR_PTR(error
);
1680 error
= path_walk(pathname
, &nd
);
1684 return ERR_PTR(error
);
1686 if (unlikely(!audit_dummy_context()))
1687 audit_inode(pathname
, nd
.path
.dentry
);
1690 * We have the parent and last component. First of all, check
1691 * that we are not asked to creat(2) an obvious directory - that
1695 if (nd
.last_type
!= LAST_NORM
|| nd
.last
.name
[nd
.last
.len
])
1699 filp
= get_empty_filp();
1702 nd
.intent
.open
.file
= filp
;
1703 nd
.intent
.open
.flags
= flag
;
1704 nd
.intent
.open
.create_mode
= mode
;
1705 dir
= nd
.path
.dentry
;
1706 nd
.flags
&= ~LOOKUP_PARENT
;
1707 nd
.flags
|= LOOKUP_CREATE
| LOOKUP_OPEN
;
1709 nd
.flags
|= LOOKUP_EXCL
;
1710 mutex_lock(&dir
->d_inode
->i_mutex
);
1711 path
.dentry
= lookup_hash(&nd
);
1712 path
.mnt
= nd
.path
.mnt
;
1715 error
= PTR_ERR(path
.dentry
);
1716 if (IS_ERR(path
.dentry
)) {
1717 mutex_unlock(&dir
->d_inode
->i_mutex
);
1721 if (IS_ERR(nd
.intent
.open
.file
)) {
1722 error
= PTR_ERR(nd
.intent
.open
.file
);
1723 goto exit_mutex_unlock
;
1726 /* Negative dentry, just create the file */
1727 if (!path
.dentry
->d_inode
) {
1729 * This write is needed to ensure that a
1730 * ro->rw transition does not occur between
1731 * the time when the file is created and when
1732 * a permanent write count is taken through
1733 * the 'struct file' in nameidata_to_filp().
1735 error
= mnt_want_write(nd
.path
.mnt
);
1737 goto exit_mutex_unlock
;
1738 error
= __open_namei_create(&nd
, &path
, flag
, mode
);
1740 mnt_drop_write(nd
.path
.mnt
);
1743 filp
= nameidata_to_filp(&nd
, open_flag
);
1745 ima_counts_put(&nd
.path
,
1746 acc_mode
& (MAY_READ
| MAY_WRITE
|
1748 mnt_drop_write(nd
.path
.mnt
);
1755 * It already exists.
1757 mutex_unlock(&dir
->d_inode
->i_mutex
);
1758 audit_inode(pathname
, path
.dentry
);
1764 if (__follow_mount(&path
)) {
1766 if (flag
& O_NOFOLLOW
)
1771 if (!path
.dentry
->d_inode
)
1773 if (path
.dentry
->d_inode
->i_op
->follow_link
)
1776 path_to_nameidata(&path
, &nd
);
1778 if (path
.dentry
->d_inode
&& S_ISDIR(path
.dentry
->d_inode
->i_mode
))
1783 * 1. may_open() truncates a file
1784 * 2. a rw->ro mount transition occurs
1785 * 3. nameidata_to_filp() fails due to
1787 * That would be inconsistent, and should
1788 * be avoided. Taking this mnt write here
1789 * ensures that (2) can not occur.
1791 will_write
= open_will_write_to_fs(flag
, nd
.path
.dentry
->d_inode
);
1793 error
= mnt_want_write(nd
.path
.mnt
);
1797 error
= may_open(&nd
.path
, acc_mode
, flag
);
1800 mnt_drop_write(nd
.path
.mnt
);
1803 filp
= nameidata_to_filp(&nd
, open_flag
);
1805 ima_counts_put(&nd
.path
,
1806 acc_mode
& (MAY_READ
| MAY_WRITE
| MAY_EXEC
));
1808 * It is now safe to drop the mnt write
1809 * because the filp has had a write taken
1813 mnt_drop_write(nd
.path
.mnt
);
1819 mutex_unlock(&dir
->d_inode
->i_mutex
);
1821 path_put_conditional(&path
, &nd
);
1823 if (!IS_ERR(nd
.intent
.open
.file
))
1824 release_open_intent(&nd
);
1829 return ERR_PTR(error
);
1833 if (flag
& O_NOFOLLOW
)
1836 * This is subtle. Instead of calling do_follow_link() we do the
1837 * thing by hands. The reason is that this way we have zero link_count
1838 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1839 * After that we have the parent and last component, i.e.
1840 * we are in the same situation as after the first path_walk().
1841 * Well, almost - if the last component is normal we get its copy
1842 * stored in nd->last.name and we will have to putname() it when we
1843 * are done. Procfs-like symlinks just set LAST_BIND.
1845 nd
.flags
|= LOOKUP_PARENT
;
1846 error
= security_inode_follow_link(path
.dentry
, &nd
);
1851 error
= __do_follow_link(&path
, &nd
);
1852 if (error
== -ESTALE
) {
1853 /* nd.path had been dropped */
1856 nd
.flags
|= LOOKUP_REVAL
;
1857 error
= __do_follow_link(&path
, &nd
);
1862 /* Does someone understand code flow here? Or it is only
1863 * me so stupid? Anathema to whoever designed this non-sense
1864 * with "intent.open".
1866 release_open_intent(&nd
);
1869 return ERR_PTR(error
);
1871 nd
.flags
&= ~LOOKUP_PARENT
;
1872 if (nd
.last_type
== LAST_BIND
)
1875 if (nd
.last_type
!= LAST_NORM
)
1877 if (nd
.last
.name
[nd
.last
.len
]) {
1878 __putname(nd
.last
.name
);
1883 __putname(nd
.last
.name
);
1886 dir
= nd
.path
.dentry
;
1887 mutex_lock(&dir
->d_inode
->i_mutex
);
1888 path
.dentry
= lookup_hash(&nd
);
1889 path
.mnt
= nd
.path
.mnt
;
1890 __putname(nd
.last
.name
);
1895 * filp_open - open file and return file pointer
1897 * @filename: path to open
1898 * @flags: open flags as per the open(2) second argument
1899 * @mode: mode for the new file if O_CREAT is set, else ignored
1901 * This is the helper to open a file from kernelspace if you really
1902 * have to. But in generally you should not do this, so please move
1903 * along, nothing to see here..
1905 struct file
*filp_open(const char *filename
, int flags
, int mode
)
1907 return do_filp_open(AT_FDCWD
, filename
, flags
, mode
, 0);
1909 EXPORT_SYMBOL(filp_open
);
1912 * lookup_create - lookup a dentry, creating it if it doesn't exist
1913 * @nd: nameidata info
1914 * @is_dir: directory flag
1916 * Simple function to lookup and return a dentry and create it
1917 * if it doesn't exist. Is SMP-safe.
1919 * Returns with nd->path.dentry->d_inode->i_mutex locked.
1921 struct dentry
*lookup_create(struct nameidata
*nd
, int is_dir
)
1923 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
1925 mutex_lock_nested(&nd
->path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1927 * Yucky last component or no last component at all?
1928 * (foo/., foo/.., /////)
1930 if (nd
->last_type
!= LAST_NORM
)
1932 nd
->flags
&= ~LOOKUP_PARENT
;
1933 nd
->flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
1934 nd
->intent
.open
.flags
= O_EXCL
;
1937 * Do the final lookup.
1939 dentry
= lookup_hash(nd
);
1943 if (dentry
->d_inode
)
1946 * Special case - lookup gave negative, but... we had foo/bar/
1947 * From the vfs_mknod() POV we just have a negative dentry -
1948 * all is fine. Let's be bastards - you had / on the end, you've
1949 * been asking for (non-existent) directory. -ENOENT for you.
1951 if (unlikely(!is_dir
&& nd
->last
.name
[nd
->last
.len
])) {
1953 dentry
= ERR_PTR(-ENOENT
);
1958 dentry
= ERR_PTR(-EEXIST
);
1962 EXPORT_SYMBOL_GPL(lookup_create
);
1964 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1966 int error
= may_create(dir
, dentry
);
1971 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
1974 if (!dir
->i_op
->mknod
)
1977 error
= devcgroup_inode_mknod(mode
, dev
);
1981 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
1986 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
1988 fsnotify_create(dir
, dentry
);
1992 static int may_mknod(mode_t mode
)
1994 switch (mode
& S_IFMT
) {
2000 case 0: /* zero mode translates to S_IFREG */
2009 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, int, mode
,
2014 struct dentry
*dentry
;
2015 struct nameidata nd
;
2020 error
= user_path_parent(dfd
, filename
, &nd
, &tmp
);
2024 dentry
= lookup_create(&nd
, 0);
2025 if (IS_ERR(dentry
)) {
2026 error
= PTR_ERR(dentry
);
2029 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2030 mode
&= ~current_umask();
2031 error
= may_mknod(mode
);
2034 error
= mnt_want_write(nd
.path
.mnt
);
2037 error
= security_path_mknod(&nd
.path
, dentry
, mode
, dev
);
2039 goto out_drop_write
;
2040 switch (mode
& S_IFMT
) {
2041 case 0: case S_IFREG
:
2042 error
= vfs_create(nd
.path
.dentry
->d_inode
,dentry
,mode
,&nd
);
2044 case S_IFCHR
: case S_IFBLK
:
2045 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,
2046 new_decode_dev(dev
));
2048 case S_IFIFO
: case S_IFSOCK
:
2049 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,0);
2053 mnt_drop_write(nd
.path
.mnt
);
2057 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2064 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, int, mode
, unsigned, dev
)
2066 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
2069 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
2071 int error
= may_create(dir
, dentry
);
2076 if (!dir
->i_op
->mkdir
)
2079 mode
&= (S_IRWXUGO
|S_ISVTX
);
2080 error
= security_inode_mkdir(dir
, dentry
, mode
);
2085 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
2087 fsnotify_mkdir(dir
, dentry
);
2091 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, int, mode
)
2095 struct dentry
*dentry
;
2096 struct nameidata nd
;
2098 error
= user_path_parent(dfd
, pathname
, &nd
, &tmp
);
2102 dentry
= lookup_create(&nd
, 1);
2103 error
= PTR_ERR(dentry
);
2107 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2108 mode
&= ~current_umask();
2109 error
= mnt_want_write(nd
.path
.mnt
);
2112 error
= security_path_mkdir(&nd
.path
, dentry
, mode
);
2114 goto out_drop_write
;
2115 error
= vfs_mkdir(nd
.path
.dentry
->d_inode
, dentry
, mode
);
2117 mnt_drop_write(nd
.path
.mnt
);
2121 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2128 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, int, mode
)
2130 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
2134 * We try to drop the dentry early: we should have
2135 * a usage count of 2 if we're the only user of this
2136 * dentry, and if that is true (possibly after pruning
2137 * the dcache), then we drop the dentry now.
2139 * A low-level filesystem can, if it choses, legally
2142 * if (!d_unhashed(dentry))
2145 * if it cannot handle the case of removing a directory
2146 * that is still in use by something else..
2148 void dentry_unhash(struct dentry
*dentry
)
2151 shrink_dcache_parent(dentry
);
2152 spin_lock(&dcache_lock
);
2153 spin_lock(&dentry
->d_lock
);
2154 if (atomic_read(&dentry
->d_count
) == 2)
2156 spin_unlock(&dentry
->d_lock
);
2157 spin_unlock(&dcache_lock
);
2160 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2162 int error
= may_delete(dir
, dentry
, 1);
2167 if (!dir
->i_op
->rmdir
)
2172 mutex_lock(&dentry
->d_inode
->i_mutex
);
2173 dentry_unhash(dentry
);
2174 if (d_mountpoint(dentry
))
2177 error
= security_inode_rmdir(dir
, dentry
);
2179 error
= dir
->i_op
->rmdir(dir
, dentry
);
2181 dentry
->d_inode
->i_flags
|= S_DEAD
;
2184 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2193 static long do_rmdir(int dfd
, const char __user
*pathname
)
2197 struct dentry
*dentry
;
2198 struct nameidata nd
;
2200 error
= user_path_parent(dfd
, pathname
, &nd
, &name
);
2204 switch(nd
.last_type
) {
2216 nd
.flags
&= ~LOOKUP_PARENT
;
2218 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2219 dentry
= lookup_hash(&nd
);
2220 error
= PTR_ERR(dentry
);
2223 error
= mnt_want_write(nd
.path
.mnt
);
2226 error
= security_path_rmdir(&nd
.path
, dentry
);
2229 error
= vfs_rmdir(nd
.path
.dentry
->d_inode
, dentry
);
2231 mnt_drop_write(nd
.path
.mnt
);
2235 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2242 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
2244 return do_rmdir(AT_FDCWD
, pathname
);
2247 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
)
2249 int error
= may_delete(dir
, dentry
, 0);
2254 if (!dir
->i_op
->unlink
)
2259 mutex_lock(&dentry
->d_inode
->i_mutex
);
2260 if (d_mountpoint(dentry
))
2263 error
= security_inode_unlink(dir
, dentry
);
2265 error
= dir
->i_op
->unlink(dir
, dentry
);
2267 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2269 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2270 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
2271 fsnotify_link_count(dentry
->d_inode
);
2279 * Make sure that the actual truncation of the file will occur outside its
2280 * directory's i_mutex. Truncate can take a long time if there is a lot of
2281 * writeout happening, and we don't want to prevent access to the directory
2282 * while waiting on the I/O.
2284 static long do_unlinkat(int dfd
, const char __user
*pathname
)
2288 struct dentry
*dentry
;
2289 struct nameidata nd
;
2290 struct inode
*inode
= NULL
;
2292 error
= user_path_parent(dfd
, pathname
, &nd
, &name
);
2297 if (nd
.last_type
!= LAST_NORM
)
2300 nd
.flags
&= ~LOOKUP_PARENT
;
2302 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2303 dentry
= lookup_hash(&nd
);
2304 error
= PTR_ERR(dentry
);
2305 if (!IS_ERR(dentry
)) {
2306 /* Why not before? Because we want correct error value */
2307 if (nd
.last
.name
[nd
.last
.len
])
2309 inode
= dentry
->d_inode
;
2311 atomic_inc(&inode
->i_count
);
2312 error
= mnt_want_write(nd
.path
.mnt
);
2315 error
= security_path_unlink(&nd
.path
, dentry
);
2318 error
= vfs_unlink(nd
.path
.dentry
->d_inode
, dentry
);
2320 mnt_drop_write(nd
.path
.mnt
);
2324 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2326 iput(inode
); /* truncate the inode here */
2333 error
= !dentry
->d_inode
? -ENOENT
:
2334 S_ISDIR(dentry
->d_inode
->i_mode
) ? -EISDIR
: -ENOTDIR
;
2338 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
2340 if ((flag
& ~AT_REMOVEDIR
) != 0)
2343 if (flag
& AT_REMOVEDIR
)
2344 return do_rmdir(dfd
, pathname
);
2346 return do_unlinkat(dfd
, pathname
);
2349 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
2351 return do_unlinkat(AT_FDCWD
, pathname
);
2354 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
2356 int error
= may_create(dir
, dentry
);
2361 if (!dir
->i_op
->symlink
)
2364 error
= security_inode_symlink(dir
, dentry
, oldname
);
2369 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
2371 fsnotify_create(dir
, dentry
);
2375 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
2376 int, newdfd
, const char __user
*, newname
)
2381 struct dentry
*dentry
;
2382 struct nameidata nd
;
2384 from
= getname(oldname
);
2386 return PTR_ERR(from
);
2388 error
= user_path_parent(newdfd
, newname
, &nd
, &to
);
2392 dentry
= lookup_create(&nd
, 0);
2393 error
= PTR_ERR(dentry
);
2397 error
= mnt_want_write(nd
.path
.mnt
);
2400 error
= security_path_symlink(&nd
.path
, dentry
, from
);
2402 goto out_drop_write
;
2403 error
= vfs_symlink(nd
.path
.dentry
->d_inode
, dentry
, from
);
2405 mnt_drop_write(nd
.path
.mnt
);
2409 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2417 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
2419 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
2422 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
)
2424 struct inode
*inode
= old_dentry
->d_inode
;
2430 error
= may_create(dir
, new_dentry
);
2434 if (dir
->i_sb
!= inode
->i_sb
)
2438 * A link to an append-only or immutable file cannot be created.
2440 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
2442 if (!dir
->i_op
->link
)
2444 if (S_ISDIR(inode
->i_mode
))
2447 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
2451 mutex_lock(&inode
->i_mutex
);
2453 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
2454 mutex_unlock(&inode
->i_mutex
);
2456 fsnotify_link(dir
, inode
, new_dentry
);
2461 * Hardlinks are often used in delicate situations. We avoid
2462 * security-related surprises by not following symlinks on the
2465 * We don't follow them on the oldname either to be compatible
2466 * with linux 2.0, and to avoid hard-linking to directories
2467 * and other special files. --ADM
2469 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
2470 int, newdfd
, const char __user
*, newname
, int, flags
)
2472 struct dentry
*new_dentry
;
2473 struct nameidata nd
;
2474 struct path old_path
;
2478 if ((flags
& ~AT_SYMLINK_FOLLOW
) != 0)
2481 error
= user_path_at(olddfd
, oldname
,
2482 flags
& AT_SYMLINK_FOLLOW
? LOOKUP_FOLLOW
: 0,
2487 error
= user_path_parent(newdfd
, newname
, &nd
, &to
);
2491 if (old_path
.mnt
!= nd
.path
.mnt
)
2493 new_dentry
= lookup_create(&nd
, 0);
2494 error
= PTR_ERR(new_dentry
);
2495 if (IS_ERR(new_dentry
))
2497 error
= mnt_want_write(nd
.path
.mnt
);
2500 error
= security_path_link(old_path
.dentry
, &nd
.path
, new_dentry
);
2502 goto out_drop_write
;
2503 error
= vfs_link(old_path
.dentry
, nd
.path
.dentry
->d_inode
, new_dentry
);
2505 mnt_drop_write(nd
.path
.mnt
);
2509 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2514 path_put(&old_path
);
2519 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
2521 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
2525 * The worst of all namespace operations - renaming directory. "Perverted"
2526 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2528 * a) we can get into loop creation. Check is done in is_subdir().
2529 * b) race potential - two innocent renames can create a loop together.
2530 * That's where 4.4 screws up. Current fix: serialization on
2531 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2533 * c) we have to lock _three_ objects - parents and victim (if it exists).
2534 * And that - after we got ->i_mutex on parents (until then we don't know
2535 * whether the target exists). Solution: try to be smart with locking
2536 * order for inodes. We rely on the fact that tree topology may change
2537 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2538 * move will be locked. Thus we can rank directories by the tree
2539 * (ancestors first) and rank all non-directories after them.
2540 * That works since everybody except rename does "lock parent, lookup,
2541 * lock child" and rename is under ->s_vfs_rename_mutex.
2542 * HOWEVER, it relies on the assumption that any object with ->lookup()
2543 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2544 * we'd better make sure that there's no link(2) for them.
2545 * d) some filesystems don't support opened-but-unlinked directories,
2546 * either because of layout or because they are not ready to deal with
2547 * all cases correctly. The latter will be fixed (taking this sort of
2548 * stuff into VFS), but the former is not going away. Solution: the same
2549 * trick as in rmdir().
2550 * e) conversion from fhandle to dentry may come in the wrong moment - when
2551 * we are removing the target. Solution: we will have to grab ->i_mutex
2552 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2553 * ->i_mutex on parents, which works but leads to some truely excessive
2556 static int vfs_rename_dir(struct inode
*old_dir
, struct dentry
*old_dentry
,
2557 struct inode
*new_dir
, struct dentry
*new_dentry
)
2560 struct inode
*target
;
2563 * If we are going to change the parent - check write permissions,
2564 * we'll need to flip '..'.
2566 if (new_dir
!= old_dir
) {
2567 error
= inode_permission(old_dentry
->d_inode
, MAY_WRITE
);
2572 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2576 target
= new_dentry
->d_inode
;
2578 mutex_lock(&target
->i_mutex
);
2579 dentry_unhash(new_dentry
);
2581 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2584 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2587 target
->i_flags
|= S_DEAD
;
2588 mutex_unlock(&target
->i_mutex
);
2589 if (d_unhashed(new_dentry
))
2590 d_rehash(new_dentry
);
2594 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2595 d_move(old_dentry
,new_dentry
);
2599 static int vfs_rename_other(struct inode
*old_dir
, struct dentry
*old_dentry
,
2600 struct inode
*new_dir
, struct dentry
*new_dentry
)
2602 struct inode
*target
;
2605 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2610 target
= new_dentry
->d_inode
;
2612 mutex_lock(&target
->i_mutex
);
2613 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2616 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2618 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2619 d_move(old_dentry
, new_dentry
);
2622 mutex_unlock(&target
->i_mutex
);
2627 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2628 struct inode
*new_dir
, struct dentry
*new_dentry
)
2631 int is_dir
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
2632 const char *old_name
;
2634 if (old_dentry
->d_inode
== new_dentry
->d_inode
)
2637 error
= may_delete(old_dir
, old_dentry
, is_dir
);
2641 if (!new_dentry
->d_inode
)
2642 error
= may_create(new_dir
, new_dentry
);
2644 error
= may_delete(new_dir
, new_dentry
, is_dir
);
2648 if (!old_dir
->i_op
->rename
)
2651 vfs_dq_init(old_dir
);
2652 vfs_dq_init(new_dir
);
2654 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
2657 error
= vfs_rename_dir(old_dir
,old_dentry
,new_dir
,new_dentry
);
2659 error
= vfs_rename_other(old_dir
,old_dentry
,new_dir
,new_dentry
);
2661 const char *new_name
= old_dentry
->d_name
.name
;
2662 fsnotify_move(old_dir
, new_dir
, old_name
, new_name
, is_dir
,
2663 new_dentry
->d_inode
, old_dentry
);
2665 fsnotify_oldname_free(old_name
);
2670 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
2671 int, newdfd
, const char __user
*, newname
)
2673 struct dentry
*old_dir
, *new_dir
;
2674 struct dentry
*old_dentry
, *new_dentry
;
2675 struct dentry
*trap
;
2676 struct nameidata oldnd
, newnd
;
2681 error
= user_path_parent(olddfd
, oldname
, &oldnd
, &from
);
2685 error
= user_path_parent(newdfd
, newname
, &newnd
, &to
);
2690 if (oldnd
.path
.mnt
!= newnd
.path
.mnt
)
2693 old_dir
= oldnd
.path
.dentry
;
2695 if (oldnd
.last_type
!= LAST_NORM
)
2698 new_dir
= newnd
.path
.dentry
;
2699 if (newnd
.last_type
!= LAST_NORM
)
2702 oldnd
.flags
&= ~LOOKUP_PARENT
;
2703 newnd
.flags
&= ~LOOKUP_PARENT
;
2704 newnd
.flags
|= LOOKUP_RENAME_TARGET
;
2706 trap
= lock_rename(new_dir
, old_dir
);
2708 old_dentry
= lookup_hash(&oldnd
);
2709 error
= PTR_ERR(old_dentry
);
2710 if (IS_ERR(old_dentry
))
2712 /* source must exist */
2714 if (!old_dentry
->d_inode
)
2716 /* unless the source is a directory trailing slashes give -ENOTDIR */
2717 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
)) {
2719 if (oldnd
.last
.name
[oldnd
.last
.len
])
2721 if (newnd
.last
.name
[newnd
.last
.len
])
2724 /* source should not be ancestor of target */
2726 if (old_dentry
== trap
)
2728 new_dentry
= lookup_hash(&newnd
);
2729 error
= PTR_ERR(new_dentry
);
2730 if (IS_ERR(new_dentry
))
2732 /* target should not be an ancestor of source */
2734 if (new_dentry
== trap
)
2737 error
= mnt_want_write(oldnd
.path
.mnt
);
2740 error
= security_path_rename(&oldnd
.path
, old_dentry
,
2741 &newnd
.path
, new_dentry
);
2744 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
2745 new_dir
->d_inode
, new_dentry
);
2747 mnt_drop_write(oldnd
.path
.mnt
);
2753 unlock_rename(new_dir
, old_dir
);
2755 path_put(&newnd
.path
);
2758 path_put(&oldnd
.path
);
2764 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
2766 return sys_renameat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
);
2769 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
, const char *link
)
2773 len
= PTR_ERR(link
);
2778 if (len
> (unsigned) buflen
)
2780 if (copy_to_user(buffer
, link
, len
))
2787 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2788 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2789 * using) it for any given inode is up to filesystem.
2791 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2793 struct nameidata nd
;
2798 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
2800 return PTR_ERR(cookie
);
2802 res
= vfs_readlink(dentry
, buffer
, buflen
, nd_get_link(&nd
));
2803 if (dentry
->d_inode
->i_op
->put_link
)
2804 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
2808 int vfs_follow_link(struct nameidata
*nd
, const char *link
)
2810 return __vfs_follow_link(nd
, link
);
2813 /* get the link contents into pagecache */
2814 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
2818 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
2819 page
= read_mapping_page(mapping
, 0, NULL
);
2824 nd_terminate_link(kaddr
, dentry
->d_inode
->i_size
, PAGE_SIZE
- 1);
2828 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2830 struct page
*page
= NULL
;
2831 char *s
= page_getlink(dentry
, &page
);
2832 int res
= vfs_readlink(dentry
,buffer
,buflen
,s
);
2835 page_cache_release(page
);
2840 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
2842 struct page
*page
= NULL
;
2843 nd_set_link(nd
, page_getlink(dentry
, &page
));
2847 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2849 struct page
*page
= cookie
;
2853 page_cache_release(page
);
2858 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
2860 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
2862 struct address_space
*mapping
= inode
->i_mapping
;
2867 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
2869 flags
|= AOP_FLAG_NOFS
;
2872 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
2873 flags
, &page
, &fsdata
);
2877 kaddr
= kmap_atomic(page
, KM_USER0
);
2878 memcpy(kaddr
, symname
, len
-1);
2879 kunmap_atomic(kaddr
, KM_USER0
);
2881 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
2888 mark_inode_dirty(inode
);
2894 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
2896 return __page_symlink(inode
, symname
, len
,
2897 !(mapping_gfp_mask(inode
->i_mapping
) & __GFP_FS
));
2900 const struct inode_operations page_symlink_inode_operations
= {
2901 .readlink
= generic_readlink
,
2902 .follow_link
= page_follow_link_light
,
2903 .put_link
= page_put_link
,
2906 EXPORT_SYMBOL(user_path_at
);
2907 EXPORT_SYMBOL(follow_down
);
2908 EXPORT_SYMBOL(follow_up
);
2909 EXPORT_SYMBOL(get_write_access
); /* binfmt_aout */
2910 EXPORT_SYMBOL(getname
);
2911 EXPORT_SYMBOL(lock_rename
);
2912 EXPORT_SYMBOL(lookup_one_len
);
2913 EXPORT_SYMBOL(page_follow_link_light
);
2914 EXPORT_SYMBOL(page_put_link
);
2915 EXPORT_SYMBOL(page_readlink
);
2916 EXPORT_SYMBOL(__page_symlink
);
2917 EXPORT_SYMBOL(page_symlink
);
2918 EXPORT_SYMBOL(page_symlink_inode_operations
);
2919 EXPORT_SYMBOL(path_lookup
);
2920 EXPORT_SYMBOL(kern_path
);
2921 EXPORT_SYMBOL(vfs_path_lookup
);
2922 EXPORT_SYMBOL(inode_permission
);
2923 EXPORT_SYMBOL(file_permission
);
2924 EXPORT_SYMBOL(unlock_rename
);
2925 EXPORT_SYMBOL(vfs_create
);
2926 EXPORT_SYMBOL(vfs_follow_link
);
2927 EXPORT_SYMBOL(vfs_link
);
2928 EXPORT_SYMBOL(vfs_mkdir
);
2929 EXPORT_SYMBOL(vfs_mknod
);
2930 EXPORT_SYMBOL(generic_permission
);
2931 EXPORT_SYMBOL(vfs_readlink
);
2932 EXPORT_SYMBOL(vfs_rename
);
2933 EXPORT_SYMBOL(vfs_rmdir
);
2934 EXPORT_SYMBOL(vfs_symlink
);
2935 EXPORT_SYMBOL(vfs_unlink
);
2936 EXPORT_SYMBOL(dentry_unhash
);
2937 EXPORT_SYMBOL(generic_readlink
);