4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * Some corrections by tytso.
11 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
14 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
21 #include <linux/namei.h>
22 #include <linux/quotaops.h>
23 #include <linux/pagemap.h>
24 #include <linux/fsnotify.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/syscalls.h>
28 #include <linux/mount.h>
29 #include <linux/audit.h>
30 #include <linux/capability.h>
31 #include <linux/file.h>
32 #include <linux/fcntl.h>
33 #include <asm/namei.h>
34 #include <asm/uaccess.h>
36 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
38 /* [Feb-1997 T. Schoebel-Theuer]
39 * Fundamental changes in the pathname lookup mechanisms (namei)
40 * were necessary because of omirr. The reason is that omirr needs
41 * to know the _real_ pathname, not the user-supplied one, in case
42 * of symlinks (and also when transname replacements occur).
44 * The new code replaces the old recursive symlink resolution with
45 * an iterative one (in case of non-nested symlink chains). It does
46 * this with calls to <fs>_follow_link().
47 * As a side effect, dir_namei(), _namei() and follow_link() are now
48 * replaced with a single function lookup_dentry() that can handle all
49 * the special cases of the former code.
51 * With the new dcache, the pathname is stored at each inode, at least as
52 * long as the refcount of the inode is positive. As a side effect, the
53 * size of the dcache depends on the inode cache and thus is dynamic.
55 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
56 * resolution to correspond with current state of the code.
58 * Note that the symlink resolution is not *completely* iterative.
59 * There is still a significant amount of tail- and mid- recursion in
60 * the algorithm. Also, note that <fs>_readlink() is not used in
61 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
62 * may return different results than <fs>_follow_link(). Many virtual
63 * filesystems (including /proc) exhibit this behavior.
66 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
67 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
68 * and the name already exists in form of a symlink, try to create the new
69 * name indicated by the symlink. The old code always complained that the
70 * name already exists, due to not following the symlink even if its target
71 * is nonexistent. The new semantics affects also mknod() and link() when
72 * the name is a symlink pointing to a non-existant name.
74 * I don't know which semantics is the right one, since I have no access
75 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
76 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
77 * "old" one. Personally, I think the new semantics is much more logical.
78 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
79 * file does succeed in both HP-UX and SunOs, but not in Solaris
80 * and in the old Linux semantics.
83 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
84 * semantics. See the comments in "open_namei" and "do_link" below.
86 * [10-Sep-98 Alan Modra] Another symlink change.
89 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
90 * inside the path - always follow.
91 * in the last component in creation/removal/renaming - never follow.
92 * if LOOKUP_FOLLOW passed - follow.
93 * if the pathname has trailing slashes - follow.
94 * otherwise - don't follow.
95 * (applied in that order).
97 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
98 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
99 * During the 2.4 we need to fix the userland stuff depending on it -
100 * hopefully we will be able to get rid of that wart in 2.5. So far only
101 * XEmacs seems to be relying on it...
104 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
105 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
106 * any extra contention...
109 static int __link_path_walk(const char *name
, struct nameidata
*nd
);
111 /* In order to reduce some races, while at the same time doing additional
112 * checking and hopefully speeding things up, we copy filenames to the
113 * kernel data space before using them..
115 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
116 * PATH_MAX includes the nul terminator --RR.
118 static int do_getname(const char __user
*filename
, char *page
)
121 unsigned long len
= PATH_MAX
;
123 if (!segment_eq(get_fs(), KERNEL_DS
)) {
124 if ((unsigned long) filename
>= TASK_SIZE
)
126 if (TASK_SIZE
- (unsigned long) filename
< PATH_MAX
)
127 len
= TASK_SIZE
- (unsigned long) filename
;
130 retval
= strncpy_from_user(page
, filename
, len
);
134 return -ENAMETOOLONG
;
140 char * getname(const char __user
* filename
)
144 result
= ERR_PTR(-ENOMEM
);
147 int retval
= do_getname(filename
, tmp
);
152 result
= ERR_PTR(retval
);
155 audit_getname(result
);
159 #ifdef CONFIG_AUDITSYSCALL
160 void putname(const char *name
)
162 if (unlikely(!audit_dummy_context()))
167 EXPORT_SYMBOL(putname
);
172 * generic_permission - check for access rights on a Posix-like filesystem
173 * @inode: inode to check access rights for
174 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
175 * @check_acl: optional callback to check for Posix ACLs
177 * Used to check for read/write/execute permissions on a file.
178 * We use "fsuid" for this, letting us set arbitrary permissions
179 * for filesystem access without changing the "normal" uids which
180 * are used for other things..
182 int generic_permission(struct inode
*inode
, int mask
,
183 int (*check_acl
)(struct inode
*inode
, int mask
))
185 umode_t mode
= inode
->i_mode
;
187 if (current
->fsuid
== inode
->i_uid
)
190 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
) && check_acl
) {
191 int error
= check_acl(inode
, mask
);
192 if (error
== -EACCES
)
193 goto check_capabilities
;
194 else if (error
!= -EAGAIN
)
198 if (in_group_p(inode
->i_gid
))
203 * If the DACs are ok we don't need any capability check.
205 if (((mode
& mask
& (MAY_READ
|MAY_WRITE
|MAY_EXEC
)) == mask
))
210 * Read/write DACs are always overridable.
211 * Executable DACs are overridable if at least one exec bit is set.
213 if (!(mask
& MAY_EXEC
) ||
214 (inode
->i_mode
& S_IXUGO
) || S_ISDIR(inode
->i_mode
))
215 if (capable(CAP_DAC_OVERRIDE
))
219 * Searching includes executable on directories, else just read.
221 if (mask
== MAY_READ
|| (S_ISDIR(inode
->i_mode
) && !(mask
& MAY_WRITE
)))
222 if (capable(CAP_DAC_READ_SEARCH
))
228 int permission(struct inode
*inode
, int mask
, struct nameidata
*nd
)
231 struct vfsmount
*mnt
= NULL
;
236 if (mask
& MAY_WRITE
) {
237 umode_t mode
= inode
->i_mode
;
240 * Nobody gets write access to a read-only fs.
242 if (IS_RDONLY(inode
) &&
243 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
247 * Nobody gets write access to an immutable file.
249 if (IS_IMMUTABLE(inode
))
253 if ((mask
& MAY_EXEC
) && S_ISREG(inode
->i_mode
)) {
255 * MAY_EXEC on regular files is denied if the fs is mounted
256 * with the "noexec" flag.
258 if (mnt
&& (mnt
->mnt_flags
& MNT_NOEXEC
))
262 /* Ordinary permission routines do not understand MAY_APPEND. */
263 submask
= mask
& ~MAY_APPEND
;
264 if (inode
->i_op
&& inode
->i_op
->permission
) {
265 retval
= inode
->i_op
->permission(inode
, submask
, nd
);
268 * Exec permission on a regular file is denied if none
269 * of the execute bits are set.
271 * This check should be done by the ->permission()
274 if ((mask
& MAY_EXEC
) && S_ISREG(inode
->i_mode
) &&
275 !(inode
->i_mode
& S_IXUGO
))
279 retval
= generic_permission(inode
, submask
, NULL
);
284 return security_inode_permission(inode
, mask
, nd
);
288 * vfs_permission - check for access rights to a given path
289 * @nd: lookup result that describes the path
290 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
292 * Used to check for read/write/execute permissions on a path.
293 * We use "fsuid" for this, letting us set arbitrary permissions
294 * for filesystem access without changing the "normal" uids which
295 * are used for other things.
297 int vfs_permission(struct nameidata
*nd
, int mask
)
299 return permission(nd
->path
.dentry
->d_inode
, mask
, nd
);
303 * file_permission - check for additional access rights to a given file
304 * @file: file to check access rights for
305 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
307 * Used to check for read/write/execute permissions on an already opened
311 * Do not use this function in new code. All access checks should
312 * be done using vfs_permission().
314 int file_permission(struct file
*file
, int mask
)
316 return permission(file
->f_path
.dentry
->d_inode
, mask
, NULL
);
320 * get_write_access() gets write permission for a file.
321 * put_write_access() releases this write permission.
322 * This is used for regular files.
323 * We cannot support write (and maybe mmap read-write shared) accesses and
324 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
325 * can have the following values:
326 * 0: no writers, no VM_DENYWRITE mappings
327 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
328 * > 0: (i_writecount) users are writing to the file.
330 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
331 * except for the cases where we don't hold i_writecount yet. Then we need to
332 * use {get,deny}_write_access() - these functions check the sign and refuse
333 * to do the change if sign is wrong. Exclusion between them is provided by
334 * the inode->i_lock spinlock.
337 int get_write_access(struct inode
* inode
)
339 spin_lock(&inode
->i_lock
);
340 if (atomic_read(&inode
->i_writecount
) < 0) {
341 spin_unlock(&inode
->i_lock
);
344 atomic_inc(&inode
->i_writecount
);
345 spin_unlock(&inode
->i_lock
);
350 int deny_write_access(struct file
* file
)
352 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
354 spin_lock(&inode
->i_lock
);
355 if (atomic_read(&inode
->i_writecount
) > 0) {
356 spin_unlock(&inode
->i_lock
);
359 atomic_dec(&inode
->i_writecount
);
360 spin_unlock(&inode
->i_lock
);
366 * path_get - get a reference to a path
367 * @path: path to get the reference to
369 * Given a path increment the reference count to the dentry and the vfsmount.
371 void path_get(struct path
*path
)
376 EXPORT_SYMBOL(path_get
);
379 * path_put - put a reference to a path
380 * @path: path to put the reference to
382 * Given a path decrement the reference count to the dentry and the vfsmount.
384 void path_put(struct path
*path
)
389 EXPORT_SYMBOL(path_put
);
392 * release_open_intent - free up open intent resources
393 * @nd: pointer to nameidata
395 void release_open_intent(struct nameidata
*nd
)
397 if (nd
->intent
.open
.file
->f_path
.dentry
== NULL
)
398 put_filp(nd
->intent
.open
.file
);
400 fput(nd
->intent
.open
.file
);
403 static inline struct dentry
*
404 do_revalidate(struct dentry
*dentry
, struct nameidata
*nd
)
406 int status
= dentry
->d_op
->d_revalidate(dentry
, nd
);
407 if (unlikely(status
<= 0)) {
409 * The dentry failed validation.
410 * If d_revalidate returned 0 attempt to invalidate
411 * the dentry otherwise d_revalidate is asking us
412 * to return a fail status.
415 if (!d_invalidate(dentry
)) {
421 dentry
= ERR_PTR(status
);
428 * Internal lookup() using the new generic dcache.
431 static struct dentry
* cached_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
433 struct dentry
* dentry
= __d_lookup(parent
, name
);
435 /* lockess __d_lookup may fail due to concurrent d_move()
436 * in some unrelated directory, so try with d_lookup
439 dentry
= d_lookup(parent
, name
);
441 if (dentry
&& dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
442 dentry
= do_revalidate(dentry
, nd
);
448 * Short-cut version of permission(), for calling by
449 * path_walk(), when dcache lock is held. Combines parts
450 * of permission() and generic_permission(), and tests ONLY for
451 * MAY_EXEC permission.
453 * If appropriate, check DAC only. If not appropriate, or
454 * short-cut DAC fails, then call permission() to do more
455 * complete permission check.
457 static int exec_permission_lite(struct inode
*inode
,
458 struct nameidata
*nd
)
460 umode_t mode
= inode
->i_mode
;
462 if (inode
->i_op
&& inode
->i_op
->permission
)
465 if (current
->fsuid
== inode
->i_uid
)
467 else if (in_group_p(inode
->i_gid
))
473 if ((inode
->i_mode
& S_IXUGO
) && capable(CAP_DAC_OVERRIDE
))
476 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_OVERRIDE
))
479 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_READ_SEARCH
))
484 return security_inode_permission(inode
, MAY_EXEC
, nd
);
488 * This is called when everything else fails, and we actually have
489 * to go to the low-level filesystem to find out what we should do..
491 * We get the directory semaphore, and after getting that we also
492 * make sure that nobody added the entry to the dcache in the meantime..
495 static struct dentry
* real_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
497 struct dentry
* result
;
498 struct inode
*dir
= parent
->d_inode
;
500 mutex_lock(&dir
->i_mutex
);
502 * First re-do the cached lookup just in case it was created
503 * while we waited for the directory semaphore..
505 * FIXME! This could use version numbering or similar to
506 * avoid unnecessary cache lookups.
508 * The "dcache_lock" is purely to protect the RCU list walker
509 * from concurrent renames at this point (we mustn't get false
510 * negatives from the RCU list walk here, unlike the optimistic
513 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
515 result
= d_lookup(parent
, name
);
517 struct dentry
*dentry
;
519 /* Don't create child dentry for a dead directory. */
520 result
= ERR_PTR(-ENOENT
);
524 dentry
= d_alloc(parent
, name
);
525 result
= ERR_PTR(-ENOMEM
);
527 result
= dir
->i_op
->lookup(dir
, dentry
, nd
);
534 mutex_unlock(&dir
->i_mutex
);
539 * Uhhuh! Nasty case: the cache was re-populated while
540 * we waited on the semaphore. Need to revalidate.
542 mutex_unlock(&dir
->i_mutex
);
543 if (result
->d_op
&& result
->d_op
->d_revalidate
) {
544 result
= do_revalidate(result
, nd
);
546 result
= ERR_PTR(-ENOENT
);
551 static int __emul_lookup_dentry(const char *, struct nameidata
*);
554 static __always_inline
int
555 walk_init_root(const char *name
, struct nameidata
*nd
)
557 struct fs_struct
*fs
= current
->fs
;
559 read_lock(&fs
->lock
);
560 if (fs
->altroot
.dentry
&& !(nd
->flags
& LOOKUP_NOALT
)) {
561 nd
->path
= fs
->altroot
;
562 path_get(&fs
->altroot
);
563 read_unlock(&fs
->lock
);
564 if (__emul_lookup_dentry(name
,nd
))
566 read_lock(&fs
->lock
);
570 read_unlock(&fs
->lock
);
575 * Wrapper to retry pathname resolution whenever the underlying
576 * file system returns an ESTALE.
578 * Retry the whole path once, forcing real lookup requests
579 * instead of relying on the dcache.
581 static __always_inline
int link_path_walk(const char *name
, struct nameidata
*nd
)
583 struct path save
= nd
->path
;
586 /* make sure the stuff we saved doesn't go away */
590 result
= __link_path_walk(name
, nd
);
591 if (result
== -ESTALE
) {
592 /* nd->path had been dropped */
594 dget(nd
->path
.dentry
);
595 mntget(nd
->path
.mnt
);
596 nd
->flags
|= LOOKUP_REVAL
;
597 result
= __link_path_walk(name
, nd
);
605 static __always_inline
int __vfs_follow_link(struct nameidata
*nd
, const char *link
)
614 if (!walk_init_root(link
, nd
))
615 /* weird __emul_prefix() stuff did it */
618 res
= link_path_walk(link
, nd
);
620 if (nd
->depth
|| res
|| nd
->last_type
!=LAST_NORM
)
623 * If it is an iterative symlinks resolution in open_namei() we
624 * have to copy the last component. And all that crap because of
625 * bloody create() on broken symlinks. Furrfu...
628 if (unlikely(!name
)) {
632 strcpy(name
, nd
->last
.name
);
633 nd
->last
.name
= name
;
637 return PTR_ERR(link
);
640 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
643 if (path
->mnt
!= nd
->path
.mnt
)
647 static inline void path_to_nameidata(struct path
*path
, struct nameidata
*nd
)
649 dput(nd
->path
.dentry
);
650 if (nd
->path
.mnt
!= path
->mnt
)
651 mntput(nd
->path
.mnt
);
652 nd
->path
.mnt
= path
->mnt
;
653 nd
->path
.dentry
= path
->dentry
;
656 static __always_inline
int __do_follow_link(struct path
*path
, struct nameidata
*nd
)
660 struct dentry
*dentry
= path
->dentry
;
662 touch_atime(path
->mnt
, dentry
);
663 nd_set_link(nd
, NULL
);
665 if (path
->mnt
!= nd
->path
.mnt
) {
666 path_to_nameidata(path
, nd
);
670 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
671 error
= PTR_ERR(cookie
);
672 if (!IS_ERR(cookie
)) {
673 char *s
= nd_get_link(nd
);
676 error
= __vfs_follow_link(nd
, s
);
677 if (dentry
->d_inode
->i_op
->put_link
)
678 dentry
->d_inode
->i_op
->put_link(dentry
, nd
, cookie
);
686 * This limits recursive symlink follows to 8, while
687 * limiting consecutive symlinks to 40.
689 * Without that kind of total limit, nasty chains of consecutive
690 * symlinks can cause almost arbitrarily long lookups.
692 static inline int do_follow_link(struct path
*path
, struct nameidata
*nd
)
695 if (current
->link_count
>= MAX_NESTED_LINKS
)
697 if (current
->total_link_count
>= 40)
699 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
701 err
= security_inode_follow_link(path
->dentry
, nd
);
704 current
->link_count
++;
705 current
->total_link_count
++;
707 err
= __do_follow_link(path
, nd
);
708 current
->link_count
--;
712 path_put_conditional(path
, nd
);
717 int follow_up(struct vfsmount
**mnt
, struct dentry
**dentry
)
719 struct vfsmount
*parent
;
720 struct dentry
*mountpoint
;
721 spin_lock(&vfsmount_lock
);
722 parent
=(*mnt
)->mnt_parent
;
723 if (parent
== *mnt
) {
724 spin_unlock(&vfsmount_lock
);
728 mountpoint
=dget((*mnt
)->mnt_mountpoint
);
729 spin_unlock(&vfsmount_lock
);
731 *dentry
= mountpoint
;
737 /* no need for dcache_lock, as serialization is taken care in
740 static int __follow_mount(struct path
*path
)
743 while (d_mountpoint(path
->dentry
)) {
744 struct vfsmount
*mounted
= lookup_mnt(path
->mnt
, path
->dentry
);
751 path
->dentry
= dget(mounted
->mnt_root
);
757 static void follow_mount(struct vfsmount
**mnt
, struct dentry
**dentry
)
759 while (d_mountpoint(*dentry
)) {
760 struct vfsmount
*mounted
= lookup_mnt(*mnt
, *dentry
);
766 *dentry
= dget(mounted
->mnt_root
);
770 /* no need for dcache_lock, as serialization is taken care in
773 int follow_down(struct vfsmount
**mnt
, struct dentry
**dentry
)
775 struct vfsmount
*mounted
;
777 mounted
= lookup_mnt(*mnt
, *dentry
);
782 *dentry
= dget(mounted
->mnt_root
);
788 static __always_inline
void follow_dotdot(struct nameidata
*nd
)
790 struct fs_struct
*fs
= current
->fs
;
793 struct vfsmount
*parent
;
794 struct dentry
*old
= nd
->path
.dentry
;
796 read_lock(&fs
->lock
);
797 if (nd
->path
.dentry
== fs
->root
.dentry
&&
798 nd
->path
.mnt
== fs
->root
.mnt
) {
799 read_unlock(&fs
->lock
);
802 read_unlock(&fs
->lock
);
803 spin_lock(&dcache_lock
);
804 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
805 nd
->path
.dentry
= dget(nd
->path
.dentry
->d_parent
);
806 spin_unlock(&dcache_lock
);
810 spin_unlock(&dcache_lock
);
811 spin_lock(&vfsmount_lock
);
812 parent
= nd
->path
.mnt
->mnt_parent
;
813 if (parent
== nd
->path
.mnt
) {
814 spin_unlock(&vfsmount_lock
);
818 nd
->path
.dentry
= dget(nd
->path
.mnt
->mnt_mountpoint
);
819 spin_unlock(&vfsmount_lock
);
821 mntput(nd
->path
.mnt
);
822 nd
->path
.mnt
= parent
;
824 follow_mount(&nd
->path
.mnt
, &nd
->path
.dentry
);
828 * It's more convoluted than I'd like it to be, but... it's still fairly
829 * small and for now I'd prefer to have fast path as straight as possible.
830 * It _is_ time-critical.
832 static int do_lookup(struct nameidata
*nd
, struct qstr
*name
,
835 struct vfsmount
*mnt
= nd
->path
.mnt
;
836 struct dentry
*dentry
= __d_lookup(nd
->path
.dentry
, name
);
840 if (dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
841 goto need_revalidate
;
844 path
->dentry
= dentry
;
845 __follow_mount(path
);
849 dentry
= real_lookup(nd
->path
.dentry
, name
, nd
);
855 dentry
= do_revalidate(dentry
, nd
);
863 return PTR_ERR(dentry
);
868 * This is the basic name resolution function, turning a pathname into
869 * the final dentry. We expect 'base' to be positive and a directory.
871 * Returns 0 and nd will have valid dentry and mnt on success.
872 * Returns error and drops reference to input namei data on failure.
874 static int __link_path_walk(const char *name
, struct nameidata
*nd
)
879 unsigned int lookup_flags
= nd
->flags
;
886 inode
= nd
->path
.dentry
->d_inode
;
888 lookup_flags
= LOOKUP_FOLLOW
| (nd
->flags
& LOOKUP_CONTINUE
);
890 /* At this point we know we have a real path component. */
896 nd
->flags
|= LOOKUP_CONTINUE
;
897 err
= exec_permission_lite(inode
, nd
);
899 err
= vfs_permission(nd
, MAY_EXEC
);
904 c
= *(const unsigned char *)name
;
906 hash
= init_name_hash();
909 hash
= partial_name_hash(c
, hash
);
910 c
= *(const unsigned char *)name
;
911 } while (c
&& (c
!= '/'));
912 this.len
= name
- (const char *) this.name
;
913 this.hash
= end_name_hash(hash
);
915 /* remove trailing slashes? */
918 while (*++name
== '/');
920 goto last_with_slashes
;
923 * "." and ".." are special - ".." especially so because it has
924 * to be able to know about the current root directory and
925 * parent relationships.
927 if (this.name
[0] == '.') switch (this.len
) {
931 if (this.name
[1] != '.')
934 inode
= nd
->path
.dentry
->d_inode
;
940 * See if the low-level filesystem might want
941 * to use its own hash..
943 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
944 err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
949 /* This does the actual lookups.. */
950 err
= do_lookup(nd
, &this, &next
);
955 inode
= next
.dentry
->d_inode
;
962 if (inode
->i_op
->follow_link
) {
963 err
= do_follow_link(&next
, nd
);
967 inode
= nd
->path
.dentry
->d_inode
;
974 path_to_nameidata(&next
, nd
);
976 if (!inode
->i_op
->lookup
)
979 /* here ends the main loop */
982 lookup_flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
984 /* Clear LOOKUP_CONTINUE iff it was previously unset */
985 nd
->flags
&= lookup_flags
| ~LOOKUP_CONTINUE
;
986 if (lookup_flags
& LOOKUP_PARENT
)
988 if (this.name
[0] == '.') switch (this.len
) {
992 if (this.name
[1] != '.')
995 inode
= nd
->path
.dentry
->d_inode
;
1000 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
1001 err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
1006 err
= do_lookup(nd
, &this, &next
);
1009 inode
= next
.dentry
->d_inode
;
1010 if ((lookup_flags
& LOOKUP_FOLLOW
)
1011 && inode
&& inode
->i_op
&& inode
->i_op
->follow_link
) {
1012 err
= do_follow_link(&next
, nd
);
1015 inode
= nd
->path
.dentry
->d_inode
;
1017 path_to_nameidata(&next
, nd
);
1021 if (lookup_flags
& LOOKUP_DIRECTORY
) {
1023 if (!inode
->i_op
|| !inode
->i_op
->lookup
)
1029 nd
->last_type
= LAST_NORM
;
1030 if (this.name
[0] != '.')
1033 nd
->last_type
= LAST_DOT
;
1034 else if (this.len
== 2 && this.name
[1] == '.')
1035 nd
->last_type
= LAST_DOTDOT
;
1040 * We bypassed the ordinary revalidation routines.
1041 * We may need to check the cached dentry for staleness.
1043 if (nd
->path
.dentry
&& nd
->path
.dentry
->d_sb
&&
1044 (nd
->path
.dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
)) {
1046 /* Note: we do not d_invalidate() */
1047 if (!nd
->path
.dentry
->d_op
->d_revalidate(
1048 nd
->path
.dentry
, nd
))
1054 path_put_conditional(&next
, nd
);
1057 path_put(&nd
->path
);
1062 static int path_walk(const char *name
, struct nameidata
*nd
)
1064 current
->total_link_count
= 0;
1065 return link_path_walk(name
, nd
);
1069 * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
1070 * everything is done. Returns 0 and drops input nd, if lookup failed;
1072 static int __emul_lookup_dentry(const char *name
, struct nameidata
*nd
)
1074 if (path_walk(name
, nd
))
1075 return 0; /* something went wrong... */
1077 if (!nd
->path
.dentry
->d_inode
||
1078 S_ISDIR(nd
->path
.dentry
->d_inode
->i_mode
)) {
1079 struct path old_path
= nd
->path
;
1080 struct qstr last
= nd
->last
;
1081 int last_type
= nd
->last_type
;
1082 struct fs_struct
*fs
= current
->fs
;
1085 * NAME was not found in alternate root or it's a directory.
1086 * Try to find it in the normal root:
1088 nd
->last_type
= LAST_ROOT
;
1089 read_lock(&fs
->lock
);
1090 nd
->path
= fs
->root
;
1091 path_get(&fs
->root
);
1092 read_unlock(&fs
->lock
);
1093 if (path_walk(name
, nd
) == 0) {
1094 if (nd
->path
.dentry
->d_inode
) {
1095 path_put(&old_path
);
1098 path_put(&nd
->path
);
1100 nd
->path
= old_path
;
1102 nd
->last_type
= last_type
;
1107 void set_fs_altroot(void)
1109 char *emul
= __emul_prefix();
1110 struct nameidata nd
;
1111 struct path path
= {}, old_path
;
1113 struct fs_struct
*fs
= current
->fs
;
1117 err
= path_lookup(emul
, LOOKUP_FOLLOW
|LOOKUP_DIRECTORY
|LOOKUP_NOALT
, &nd
);
1121 write_lock(&fs
->lock
);
1122 old_path
= fs
->altroot
;
1124 write_unlock(&fs
->lock
);
1125 if (old_path
.dentry
)
1126 path_put(&old_path
);
1129 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1130 static int do_path_lookup(int dfd
, const char *name
,
1131 unsigned int flags
, struct nameidata
*nd
)
1136 struct fs_struct
*fs
= current
->fs
;
1138 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1143 read_lock(&fs
->lock
);
1144 if (fs
->altroot
.dentry
&& !(nd
->flags
& LOOKUP_NOALT
)) {
1145 nd
->path
= fs
->altroot
;
1146 path_get(&fs
->altroot
);
1147 read_unlock(&fs
->lock
);
1148 if (__emul_lookup_dentry(name
,nd
))
1149 goto out
; /* found in altroot */
1150 read_lock(&fs
->lock
);
1152 nd
->path
= fs
->root
;
1153 path_get(&fs
->root
);
1154 read_unlock(&fs
->lock
);
1155 } else if (dfd
== AT_FDCWD
) {
1156 read_lock(&fs
->lock
);
1159 read_unlock(&fs
->lock
);
1161 struct dentry
*dentry
;
1163 file
= fget_light(dfd
, &fput_needed
);
1168 dentry
= file
->f_path
.dentry
;
1171 if (!S_ISDIR(dentry
->d_inode
->i_mode
))
1174 retval
= file_permission(file
, MAY_EXEC
);
1178 nd
->path
= file
->f_path
;
1179 path_get(&file
->f_path
);
1181 fput_light(file
, fput_needed
);
1184 retval
= path_walk(name
, nd
);
1186 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1187 nd
->path
.dentry
->d_inode
))
1188 audit_inode(name
, nd
->path
.dentry
);
1193 fput_light(file
, fput_needed
);
1197 int path_lookup(const char *name
, unsigned int flags
,
1198 struct nameidata
*nd
)
1200 return do_path_lookup(AT_FDCWD
, name
, flags
, nd
);
1204 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1205 * @dentry: pointer to dentry of the base directory
1206 * @mnt: pointer to vfs mount of the base directory
1207 * @name: pointer to file name
1208 * @flags: lookup flags
1209 * @nd: pointer to nameidata
1211 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
1212 const char *name
, unsigned int flags
,
1213 struct nameidata
*nd
)
1217 /* same as do_path_lookup */
1218 nd
->last_type
= LAST_ROOT
;
1222 nd
->path
.mnt
= mntget(mnt
);
1223 nd
->path
.dentry
= dget(dentry
);
1225 retval
= path_walk(name
, nd
);
1226 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1227 nd
->path
.dentry
->d_inode
))
1228 audit_inode(name
, nd
->path
.dentry
);
1234 static int __path_lookup_intent_open(int dfd
, const char *name
,
1235 unsigned int lookup_flags
, struct nameidata
*nd
,
1236 int open_flags
, int create_mode
)
1238 struct file
*filp
= get_empty_filp();
1243 nd
->intent
.open
.file
= filp
;
1244 nd
->intent
.open
.flags
= open_flags
;
1245 nd
->intent
.open
.create_mode
= create_mode
;
1246 err
= do_path_lookup(dfd
, name
, lookup_flags
|LOOKUP_OPEN
, nd
);
1247 if (IS_ERR(nd
->intent
.open
.file
)) {
1249 err
= PTR_ERR(nd
->intent
.open
.file
);
1250 path_put(&nd
->path
);
1252 } else if (err
!= 0)
1253 release_open_intent(nd
);
1258 * path_lookup_open - lookup a file path with open intent
1259 * @dfd: the directory to use as base, or AT_FDCWD
1260 * @name: pointer to file name
1261 * @lookup_flags: lookup intent flags
1262 * @nd: pointer to nameidata
1263 * @open_flags: open intent flags
1265 int path_lookup_open(int dfd
, const char *name
, unsigned int lookup_flags
,
1266 struct nameidata
*nd
, int open_flags
)
1268 return __path_lookup_intent_open(dfd
, name
, lookup_flags
, nd
,
1273 * path_lookup_create - lookup a file path with open + create intent
1274 * @dfd: the directory to use as base, or AT_FDCWD
1275 * @name: pointer to file name
1276 * @lookup_flags: lookup intent flags
1277 * @nd: pointer to nameidata
1278 * @open_flags: open intent flags
1279 * @create_mode: create intent flags
1281 static int path_lookup_create(int dfd
, const char *name
,
1282 unsigned int lookup_flags
, struct nameidata
*nd
,
1283 int open_flags
, int create_mode
)
1285 return __path_lookup_intent_open(dfd
, name
, lookup_flags
|LOOKUP_CREATE
,
1286 nd
, open_flags
, create_mode
);
1289 int __user_path_lookup_open(const char __user
*name
, unsigned int lookup_flags
,
1290 struct nameidata
*nd
, int open_flags
)
1292 char *tmp
= getname(name
);
1293 int err
= PTR_ERR(tmp
);
1296 err
= __path_lookup_intent_open(AT_FDCWD
, tmp
, lookup_flags
, nd
, open_flags
, 0);
1302 static struct dentry
*__lookup_hash(struct qstr
*name
,
1303 struct dentry
*base
, struct nameidata
*nd
)
1305 struct dentry
*dentry
;
1306 struct inode
*inode
;
1309 inode
= base
->d_inode
;
1312 * See if the low-level filesystem might want
1313 * to use its own hash..
1315 if (base
->d_op
&& base
->d_op
->d_hash
) {
1316 err
= base
->d_op
->d_hash(base
, name
);
1317 dentry
= ERR_PTR(err
);
1322 dentry
= cached_lookup(base
, name
, nd
);
1326 /* Don't create child dentry for a dead directory. */
1327 dentry
= ERR_PTR(-ENOENT
);
1328 if (IS_DEADDIR(inode
))
1331 new = d_alloc(base
, name
);
1332 dentry
= ERR_PTR(-ENOMEM
);
1335 dentry
= inode
->i_op
->lookup(inode
, new, nd
);
1346 * Restricted form of lookup. Doesn't follow links, single-component only,
1347 * needs parent already locked. Doesn't follow mounts.
1350 static struct dentry
*lookup_hash(struct nameidata
*nd
)
1354 err
= permission(nd
->path
.dentry
->d_inode
, MAY_EXEC
, nd
);
1356 return ERR_PTR(err
);
1357 return __lookup_hash(&nd
->last
, nd
->path
.dentry
, nd
);
1360 static int __lookup_one_len(const char *name
, struct qstr
*this,
1361 struct dentry
*base
, int len
)
1371 hash
= init_name_hash();
1373 c
= *(const unsigned char *)name
++;
1374 if (c
== '/' || c
== '\0')
1376 hash
= partial_name_hash(c
, hash
);
1378 this->hash
= end_name_hash(hash
);
1383 * lookup_one_len - filesystem helper to lookup single pathname component
1384 * @name: pathname component to lookup
1385 * @base: base directory to lookup from
1386 * @len: maximum length @len should be interpreted to
1388 * Note that this routine is purely a helper for filesystem usage and should
1389 * not be called by generic code. Also note that by using this function the
1390 * nameidata argument is passed to the filesystem methods and a filesystem
1391 * using this helper needs to be prepared for that.
1393 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
1398 err
= __lookup_one_len(name
, &this, base
, len
);
1400 return ERR_PTR(err
);
1402 err
= permission(base
->d_inode
, MAY_EXEC
, NULL
);
1404 return ERR_PTR(err
);
1405 return __lookup_hash(&this, base
, NULL
);
1409 * lookup_one_noperm - bad hack for sysfs
1410 * @name: pathname component to lookup
1411 * @base: base directory to lookup from
1413 * This is a variant of lookup_one_len that doesn't perform any permission
1414 * checks. It's a horrible hack to work around the braindead sysfs
1415 * architecture and should not be used anywhere else.
1417 * DON'T USE THIS FUNCTION EVER, thanks.
1419 struct dentry
*lookup_one_noperm(const char *name
, struct dentry
*base
)
1424 err
= __lookup_one_len(name
, &this, base
, strlen(name
));
1426 return ERR_PTR(err
);
1427 return __lookup_hash(&this, base
, NULL
);
1430 int __user_walk_fd(int dfd
, const char __user
*name
, unsigned flags
,
1431 struct nameidata
*nd
)
1433 char *tmp
= getname(name
);
1434 int err
= PTR_ERR(tmp
);
1437 err
= do_path_lookup(dfd
, tmp
, flags
, nd
);
1443 int __user_walk(const char __user
*name
, unsigned flags
, struct nameidata
*nd
)
1445 return __user_walk_fd(AT_FDCWD
, name
, flags
, nd
);
1449 * It's inline, so penalty for filesystems that don't use sticky bit is
1452 static inline int check_sticky(struct inode
*dir
, struct inode
*inode
)
1454 if (!(dir
->i_mode
& S_ISVTX
))
1456 if (inode
->i_uid
== current
->fsuid
)
1458 if (dir
->i_uid
== current
->fsuid
)
1460 return !capable(CAP_FOWNER
);
1464 * Check whether we can remove a link victim from directory dir, check
1465 * whether the type of victim is right.
1466 * 1. We can't do it if dir is read-only (done in permission())
1467 * 2. We should have write and exec permissions on dir
1468 * 3. We can't remove anything from append-only dir
1469 * 4. We can't do anything with immutable dir (done in permission())
1470 * 5. If the sticky bit on dir is set we should either
1471 * a. be owner of dir, or
1472 * b. be owner of victim, or
1473 * c. have CAP_FOWNER capability
1474 * 6. If the victim is append-only or immutable we can't do antyhing with
1475 * links pointing to it.
1476 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1477 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1478 * 9. We can't remove a root or mountpoint.
1479 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1480 * nfs_async_unlink().
1482 static int may_delete(struct inode
*dir
,struct dentry
*victim
,int isdir
)
1486 if (!victim
->d_inode
)
1489 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
1490 audit_inode_child(victim
->d_name
.name
, victim
, dir
);
1492 error
= permission(dir
,MAY_WRITE
| MAY_EXEC
, NULL
);
1497 if (check_sticky(dir
, victim
->d_inode
)||IS_APPEND(victim
->d_inode
)||
1498 IS_IMMUTABLE(victim
->d_inode
))
1501 if (!S_ISDIR(victim
->d_inode
->i_mode
))
1503 if (IS_ROOT(victim
))
1505 } else if (S_ISDIR(victim
->d_inode
->i_mode
))
1507 if (IS_DEADDIR(dir
))
1509 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
1514 /* Check whether we can create an object with dentry child in directory
1516 * 1. We can't do it if child already exists (open has special treatment for
1517 * this case, but since we are inlined it's OK)
1518 * 2. We can't do it if dir is read-only (done in permission())
1519 * 3. We should have write and exec permissions on dir
1520 * 4. We can't do it if dir is immutable (done in permission())
1522 static inline int may_create(struct inode
*dir
, struct dentry
*child
,
1523 struct nameidata
*nd
)
1527 if (IS_DEADDIR(dir
))
1529 return permission(dir
,MAY_WRITE
| MAY_EXEC
, nd
);
1533 * O_DIRECTORY translates into forcing a directory lookup.
1535 static inline int lookup_flags(unsigned int f
)
1537 unsigned long retval
= LOOKUP_FOLLOW
;
1540 retval
&= ~LOOKUP_FOLLOW
;
1542 if (f
& O_DIRECTORY
)
1543 retval
|= LOOKUP_DIRECTORY
;
1549 * p1 and p2 should be directories on the same fs.
1551 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
1556 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1560 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1562 for (p
= p1
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1563 if (p
->d_parent
== p2
) {
1564 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1565 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1570 for (p
= p2
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1571 if (p
->d_parent
== p1
) {
1572 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1573 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1578 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1579 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1583 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
1585 mutex_unlock(&p1
->d_inode
->i_mutex
);
1587 mutex_unlock(&p2
->d_inode
->i_mutex
);
1588 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1592 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1593 struct nameidata
*nd
)
1595 int error
= may_create(dir
, dentry
, nd
);
1600 if (!dir
->i_op
|| !dir
->i_op
->create
)
1601 return -EACCES
; /* shouldn't it be ENOSYS? */
1604 error
= security_inode_create(dir
, dentry
, mode
);
1608 error
= dir
->i_op
->create(dir
, dentry
, mode
, nd
);
1610 fsnotify_create(dir
, dentry
);
1614 int may_open(struct nameidata
*nd
, int acc_mode
, int flag
)
1616 struct dentry
*dentry
= nd
->path
.dentry
;
1617 struct inode
*inode
= dentry
->d_inode
;
1623 if (S_ISLNK(inode
->i_mode
))
1626 if (S_ISDIR(inode
->i_mode
) && (acc_mode
& MAY_WRITE
))
1630 * FIFO's, sockets and device files are special: they don't
1631 * actually live on the filesystem itself, and as such you
1632 * can write to them even if the filesystem is read-only.
1634 if (S_ISFIFO(inode
->i_mode
) || S_ISSOCK(inode
->i_mode
)) {
1636 } else if (S_ISBLK(inode
->i_mode
) || S_ISCHR(inode
->i_mode
)) {
1637 if (nd
->path
.mnt
->mnt_flags
& MNT_NODEV
)
1641 } else if (IS_RDONLY(inode
) && (acc_mode
& MAY_WRITE
))
1644 error
= vfs_permission(nd
, acc_mode
);
1648 * An append-only file must be opened in append mode for writing.
1650 if (IS_APPEND(inode
)) {
1651 if ((flag
& FMODE_WRITE
) && !(flag
& O_APPEND
))
1657 /* O_NOATIME can only be set by the owner or superuser */
1658 if (flag
& O_NOATIME
)
1659 if (!is_owner_or_cap(inode
))
1663 * Ensure there are no outstanding leases on the file.
1665 error
= break_lease(inode
, flag
);
1669 if (flag
& O_TRUNC
) {
1670 error
= get_write_access(inode
);
1675 * Refuse to truncate files with mandatory locks held on them.
1677 error
= locks_verify_locked(inode
);
1681 error
= do_truncate(dentry
, 0,
1682 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
1685 put_write_access(inode
);
1689 if (flag
& FMODE_WRITE
)
1695 static int open_namei_create(struct nameidata
*nd
, struct path
*path
,
1699 struct dentry
*dir
= nd
->path
.dentry
;
1701 if (!IS_POSIXACL(dir
->d_inode
))
1702 mode
&= ~current
->fs
->umask
;
1703 error
= vfs_create(dir
->d_inode
, path
->dentry
, mode
, nd
);
1704 mutex_unlock(&dir
->d_inode
->i_mutex
);
1705 dput(nd
->path
.dentry
);
1706 nd
->path
.dentry
= path
->dentry
;
1709 /* Don't check for write permission, don't truncate */
1710 return may_open(nd
, 0, flag
& ~O_TRUNC
);
1716 * namei for open - this is in fact almost the whole open-routine.
1718 * Note that the low bits of "flag" aren't the same as in the open
1719 * system call - they are 00 - no permissions needed
1720 * 01 - read permission needed
1721 * 10 - write permission needed
1722 * 11 - read/write permissions needed
1723 * which is a lot more logical, and also allows the "no perm" needed
1724 * for symlinks (where the permissions are checked later).
1727 int open_namei(int dfd
, const char *pathname
, int flag
,
1728 int mode
, struct nameidata
*nd
)
1730 int acc_mode
, error
;
1735 acc_mode
= ACC_MODE(flag
);
1737 /* O_TRUNC implies we need access checks for write permissions */
1739 acc_mode
|= MAY_WRITE
;
1741 /* Allow the LSM permission hook to distinguish append
1742 access from general write access. */
1743 if (flag
& O_APPEND
)
1744 acc_mode
|= MAY_APPEND
;
1747 * The simplest case - just a plain lookup.
1749 if (!(flag
& O_CREAT
)) {
1750 error
= path_lookup_open(dfd
, pathname
, lookup_flags(flag
),
1758 * Create - we need to know the parent.
1760 error
= path_lookup_create(dfd
,pathname
,LOOKUP_PARENT
,nd
,flag
,mode
);
1765 * We have the parent and last component. First of all, check
1766 * that we are not asked to creat(2) an obvious directory - that
1770 if (nd
->last_type
!= LAST_NORM
|| nd
->last
.name
[nd
->last
.len
])
1773 dir
= nd
->path
.dentry
;
1774 nd
->flags
&= ~LOOKUP_PARENT
;
1775 mutex_lock(&dir
->d_inode
->i_mutex
);
1776 path
.dentry
= lookup_hash(nd
);
1777 path
.mnt
= nd
->path
.mnt
;
1780 error
= PTR_ERR(path
.dentry
);
1781 if (IS_ERR(path
.dentry
)) {
1782 mutex_unlock(&dir
->d_inode
->i_mutex
);
1786 if (IS_ERR(nd
->intent
.open
.file
)) {
1787 mutex_unlock(&dir
->d_inode
->i_mutex
);
1788 error
= PTR_ERR(nd
->intent
.open
.file
);
1792 /* Negative dentry, just create the file */
1793 if (!path
.dentry
->d_inode
) {
1794 error
= open_namei_create(nd
, &path
, flag
, mode
);
1801 * It already exists.
1803 mutex_unlock(&dir
->d_inode
->i_mutex
);
1804 audit_inode(pathname
, path
.dentry
);
1810 if (__follow_mount(&path
)) {
1812 if (flag
& O_NOFOLLOW
)
1817 if (!path
.dentry
->d_inode
)
1819 if (path
.dentry
->d_inode
->i_op
&& path
.dentry
->d_inode
->i_op
->follow_link
)
1822 path_to_nameidata(&path
, nd
);
1824 if (path
.dentry
->d_inode
&& S_ISDIR(path
.dentry
->d_inode
->i_mode
))
1827 error
= may_open(nd
, acc_mode
, flag
);
1833 path_put_conditional(&path
, nd
);
1835 if (!IS_ERR(nd
->intent
.open
.file
))
1836 release_open_intent(nd
);
1837 path_put(&nd
->path
);
1842 if (flag
& O_NOFOLLOW
)
1845 * This is subtle. Instead of calling do_follow_link() we do the
1846 * thing by hands. The reason is that this way we have zero link_count
1847 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1848 * After that we have the parent and last component, i.e.
1849 * we are in the same situation as after the first path_walk().
1850 * Well, almost - if the last component is normal we get its copy
1851 * stored in nd->last.name and we will have to putname() it when we
1852 * are done. Procfs-like symlinks just set LAST_BIND.
1854 nd
->flags
|= LOOKUP_PARENT
;
1855 error
= security_inode_follow_link(path
.dentry
, nd
);
1858 error
= __do_follow_link(&path
, nd
);
1860 /* Does someone understand code flow here? Or it is only
1861 * me so stupid? Anathema to whoever designed this non-sense
1862 * with "intent.open".
1864 release_open_intent(nd
);
1867 nd
->flags
&= ~LOOKUP_PARENT
;
1868 if (nd
->last_type
== LAST_BIND
)
1871 if (nd
->last_type
!= LAST_NORM
)
1873 if (nd
->last
.name
[nd
->last
.len
]) {
1874 __putname(nd
->last
.name
);
1879 __putname(nd
->last
.name
);
1882 dir
= nd
->path
.dentry
;
1883 mutex_lock(&dir
->d_inode
->i_mutex
);
1884 path
.dentry
= lookup_hash(nd
);
1885 path
.mnt
= nd
->path
.mnt
;
1886 __putname(nd
->last
.name
);
1891 * lookup_create - lookup a dentry, creating it if it doesn't exist
1892 * @nd: nameidata info
1893 * @is_dir: directory flag
1895 * Simple function to lookup and return a dentry and create it
1896 * if it doesn't exist. Is SMP-safe.
1898 * Returns with nd->path.dentry->d_inode->i_mutex locked.
1900 struct dentry
*lookup_create(struct nameidata
*nd
, int is_dir
)
1902 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
1904 mutex_lock_nested(&nd
->path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1906 * Yucky last component or no last component at all?
1907 * (foo/., foo/.., /////)
1909 if (nd
->last_type
!= LAST_NORM
)
1911 nd
->flags
&= ~LOOKUP_PARENT
;
1912 nd
->flags
|= LOOKUP_CREATE
;
1913 nd
->intent
.open
.flags
= O_EXCL
;
1916 * Do the final lookup.
1918 dentry
= lookup_hash(nd
);
1922 if (dentry
->d_inode
)
1925 * Special case - lookup gave negative, but... we had foo/bar/
1926 * From the vfs_mknod() POV we just have a negative dentry -
1927 * all is fine. Let's be bastards - you had / on the end, you've
1928 * been asking for (non-existent) directory. -ENOENT for you.
1930 if (unlikely(!is_dir
&& nd
->last
.name
[nd
->last
.len
])) {
1932 dentry
= ERR_PTR(-ENOENT
);
1937 dentry
= ERR_PTR(-EEXIST
);
1941 EXPORT_SYMBOL_GPL(lookup_create
);
1943 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1945 int error
= may_create(dir
, dentry
, NULL
);
1950 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
1953 if (!dir
->i_op
|| !dir
->i_op
->mknod
)
1956 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
1961 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
1963 fsnotify_create(dir
, dentry
);
1967 asmlinkage
long sys_mknodat(int dfd
, const char __user
*filename
, int mode
,
1972 struct dentry
* dentry
;
1973 struct nameidata nd
;
1977 tmp
= getname(filename
);
1979 return PTR_ERR(tmp
);
1981 error
= do_path_lookup(dfd
, tmp
, LOOKUP_PARENT
, &nd
);
1984 dentry
= lookup_create(&nd
, 0);
1985 error
= PTR_ERR(dentry
);
1987 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
1988 mode
&= ~current
->fs
->umask
;
1989 if (!IS_ERR(dentry
)) {
1990 switch (mode
& S_IFMT
) {
1991 case 0: case S_IFREG
:
1992 error
= vfs_create(nd
.path
.dentry
->d_inode
,dentry
,mode
,&nd
);
1994 case S_IFCHR
: case S_IFBLK
:
1995 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,
1996 new_decode_dev(dev
));
1998 case S_IFIFO
: case S_IFSOCK
:
1999 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,0);
2009 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2017 asmlinkage
long sys_mknod(const char __user
*filename
, int mode
, unsigned dev
)
2019 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
2022 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
2024 int error
= may_create(dir
, dentry
, NULL
);
2029 if (!dir
->i_op
|| !dir
->i_op
->mkdir
)
2032 mode
&= (S_IRWXUGO
|S_ISVTX
);
2033 error
= security_inode_mkdir(dir
, dentry
, mode
);
2038 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
2040 fsnotify_mkdir(dir
, dentry
);
2044 asmlinkage
long sys_mkdirat(int dfd
, const char __user
*pathname
, int mode
)
2048 struct dentry
*dentry
;
2049 struct nameidata nd
;
2051 tmp
= getname(pathname
);
2052 error
= PTR_ERR(tmp
);
2056 error
= do_path_lookup(dfd
, tmp
, LOOKUP_PARENT
, &nd
);
2059 dentry
= lookup_create(&nd
, 1);
2060 error
= PTR_ERR(dentry
);
2064 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2065 mode
&= ~current
->fs
->umask
;
2066 error
= vfs_mkdir(nd
.path
.dentry
->d_inode
, dentry
, mode
);
2069 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2077 asmlinkage
long sys_mkdir(const char __user
*pathname
, int mode
)
2079 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
2083 * We try to drop the dentry early: we should have
2084 * a usage count of 2 if we're the only user of this
2085 * dentry, and if that is true (possibly after pruning
2086 * the dcache), then we drop the dentry now.
2088 * A low-level filesystem can, if it choses, legally
2091 * if (!d_unhashed(dentry))
2094 * if it cannot handle the case of removing a directory
2095 * that is still in use by something else..
2097 void dentry_unhash(struct dentry
*dentry
)
2100 shrink_dcache_parent(dentry
);
2101 spin_lock(&dcache_lock
);
2102 spin_lock(&dentry
->d_lock
);
2103 if (atomic_read(&dentry
->d_count
) == 2)
2105 spin_unlock(&dentry
->d_lock
);
2106 spin_unlock(&dcache_lock
);
2109 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2111 int error
= may_delete(dir
, dentry
, 1);
2116 if (!dir
->i_op
|| !dir
->i_op
->rmdir
)
2121 mutex_lock(&dentry
->d_inode
->i_mutex
);
2122 dentry_unhash(dentry
);
2123 if (d_mountpoint(dentry
))
2126 error
= security_inode_rmdir(dir
, dentry
);
2128 error
= dir
->i_op
->rmdir(dir
, dentry
);
2130 dentry
->d_inode
->i_flags
|= S_DEAD
;
2133 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2142 static long do_rmdir(int dfd
, const char __user
*pathname
)
2146 struct dentry
*dentry
;
2147 struct nameidata nd
;
2149 name
= getname(pathname
);
2151 return PTR_ERR(name
);
2153 error
= do_path_lookup(dfd
, name
, LOOKUP_PARENT
, &nd
);
2157 switch(nd
.last_type
) {
2168 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2169 dentry
= lookup_hash(&nd
);
2170 error
= PTR_ERR(dentry
);
2173 error
= vfs_rmdir(nd
.path
.dentry
->d_inode
, dentry
);
2176 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2184 asmlinkage
long sys_rmdir(const char __user
*pathname
)
2186 return do_rmdir(AT_FDCWD
, pathname
);
2189 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
)
2191 int error
= may_delete(dir
, dentry
, 0);
2196 if (!dir
->i_op
|| !dir
->i_op
->unlink
)
2201 mutex_lock(&dentry
->d_inode
->i_mutex
);
2202 if (d_mountpoint(dentry
))
2205 error
= security_inode_unlink(dir
, dentry
);
2207 error
= dir
->i_op
->unlink(dir
, dentry
);
2209 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2211 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2212 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
2213 fsnotify_link_count(dentry
->d_inode
);
2221 * Make sure that the actual truncation of the file will occur outside its
2222 * directory's i_mutex. Truncate can take a long time if there is a lot of
2223 * writeout happening, and we don't want to prevent access to the directory
2224 * while waiting on the I/O.
2226 static long do_unlinkat(int dfd
, const char __user
*pathname
)
2230 struct dentry
*dentry
;
2231 struct nameidata nd
;
2232 struct inode
*inode
= NULL
;
2234 name
= getname(pathname
);
2236 return PTR_ERR(name
);
2238 error
= do_path_lookup(dfd
, name
, LOOKUP_PARENT
, &nd
);
2242 if (nd
.last_type
!= LAST_NORM
)
2244 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2245 dentry
= lookup_hash(&nd
);
2246 error
= PTR_ERR(dentry
);
2247 if (!IS_ERR(dentry
)) {
2248 /* Why not before? Because we want correct error value */
2249 if (nd
.last
.name
[nd
.last
.len
])
2251 inode
= dentry
->d_inode
;
2253 atomic_inc(&inode
->i_count
);
2254 error
= vfs_unlink(nd
.path
.dentry
->d_inode
, dentry
);
2258 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2260 iput(inode
); /* truncate the inode here */
2268 error
= !dentry
->d_inode
? -ENOENT
:
2269 S_ISDIR(dentry
->d_inode
->i_mode
) ? -EISDIR
: -ENOTDIR
;
2273 asmlinkage
long sys_unlinkat(int dfd
, const char __user
*pathname
, int flag
)
2275 if ((flag
& ~AT_REMOVEDIR
) != 0)
2278 if (flag
& AT_REMOVEDIR
)
2279 return do_rmdir(dfd
, pathname
);
2281 return do_unlinkat(dfd
, pathname
);
2284 asmlinkage
long sys_unlink(const char __user
*pathname
)
2286 return do_unlinkat(AT_FDCWD
, pathname
);
2289 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
, int mode
)
2291 int error
= may_create(dir
, dentry
, NULL
);
2296 if (!dir
->i_op
|| !dir
->i_op
->symlink
)
2299 error
= security_inode_symlink(dir
, dentry
, oldname
);
2304 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
2306 fsnotify_create(dir
, dentry
);
2310 asmlinkage
long sys_symlinkat(const char __user
*oldname
,
2311 int newdfd
, const char __user
*newname
)
2316 struct dentry
*dentry
;
2317 struct nameidata nd
;
2319 from
= getname(oldname
);
2321 return PTR_ERR(from
);
2322 to
= getname(newname
);
2323 error
= PTR_ERR(to
);
2327 error
= do_path_lookup(newdfd
, to
, LOOKUP_PARENT
, &nd
);
2330 dentry
= lookup_create(&nd
, 0);
2331 error
= PTR_ERR(dentry
);
2335 error
= vfs_symlink(nd
.path
.dentry
->d_inode
, dentry
, from
, S_IALLUGO
);
2338 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2347 asmlinkage
long sys_symlink(const char __user
*oldname
, const char __user
*newname
)
2349 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
2352 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
)
2354 struct inode
*inode
= old_dentry
->d_inode
;
2360 error
= may_create(dir
, new_dentry
, NULL
);
2364 if (dir
->i_sb
!= inode
->i_sb
)
2368 * A link to an append-only or immutable file cannot be created.
2370 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
2372 if (!dir
->i_op
|| !dir
->i_op
->link
)
2374 if (S_ISDIR(old_dentry
->d_inode
->i_mode
))
2377 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
2381 mutex_lock(&old_dentry
->d_inode
->i_mutex
);
2383 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
2384 mutex_unlock(&old_dentry
->d_inode
->i_mutex
);
2386 fsnotify_link(dir
, old_dentry
->d_inode
, new_dentry
);
2391 * Hardlinks are often used in delicate situations. We avoid
2392 * security-related surprises by not following symlinks on the
2395 * We don't follow them on the oldname either to be compatible
2396 * with linux 2.0, and to avoid hard-linking to directories
2397 * and other special files. --ADM
2399 asmlinkage
long sys_linkat(int olddfd
, const char __user
*oldname
,
2400 int newdfd
, const char __user
*newname
,
2403 struct dentry
*new_dentry
;
2404 struct nameidata nd
, old_nd
;
2408 if ((flags
& ~AT_SYMLINK_FOLLOW
) != 0)
2411 to
= getname(newname
);
2415 error
= __user_walk_fd(olddfd
, oldname
,
2416 flags
& AT_SYMLINK_FOLLOW
? LOOKUP_FOLLOW
: 0,
2420 error
= do_path_lookup(newdfd
, to
, LOOKUP_PARENT
, &nd
);
2424 if (old_nd
.path
.mnt
!= nd
.path
.mnt
)
2426 new_dentry
= lookup_create(&nd
, 0);
2427 error
= PTR_ERR(new_dentry
);
2428 if (IS_ERR(new_dentry
))
2430 error
= vfs_link(old_nd
.path
.dentry
, nd
.path
.dentry
->d_inode
, new_dentry
);
2433 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2437 path_put(&old_nd
.path
);
2444 asmlinkage
long sys_link(const char __user
*oldname
, const char __user
*newname
)
2446 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
2450 * The worst of all namespace operations - renaming directory. "Perverted"
2451 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2453 * a) we can get into loop creation. Check is done in is_subdir().
2454 * b) race potential - two innocent renames can create a loop together.
2455 * That's where 4.4 screws up. Current fix: serialization on
2456 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2458 * c) we have to lock _three_ objects - parents and victim (if it exists).
2459 * And that - after we got ->i_mutex on parents (until then we don't know
2460 * whether the target exists). Solution: try to be smart with locking
2461 * order for inodes. We rely on the fact that tree topology may change
2462 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2463 * move will be locked. Thus we can rank directories by the tree
2464 * (ancestors first) and rank all non-directories after them.
2465 * That works since everybody except rename does "lock parent, lookup,
2466 * lock child" and rename is under ->s_vfs_rename_mutex.
2467 * HOWEVER, it relies on the assumption that any object with ->lookup()
2468 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2469 * we'd better make sure that there's no link(2) for them.
2470 * d) some filesystems don't support opened-but-unlinked directories,
2471 * either because of layout or because they are not ready to deal with
2472 * all cases correctly. The latter will be fixed (taking this sort of
2473 * stuff into VFS), but the former is not going away. Solution: the same
2474 * trick as in rmdir().
2475 * e) conversion from fhandle to dentry may come in the wrong moment - when
2476 * we are removing the target. Solution: we will have to grab ->i_mutex
2477 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2478 * ->i_mutex on parents, which works but leads to some truely excessive
2481 static int vfs_rename_dir(struct inode
*old_dir
, struct dentry
*old_dentry
,
2482 struct inode
*new_dir
, struct dentry
*new_dentry
)
2485 struct inode
*target
;
2488 * If we are going to change the parent - check write permissions,
2489 * we'll need to flip '..'.
2491 if (new_dir
!= old_dir
) {
2492 error
= permission(old_dentry
->d_inode
, MAY_WRITE
, NULL
);
2497 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2501 target
= new_dentry
->d_inode
;
2503 mutex_lock(&target
->i_mutex
);
2504 dentry_unhash(new_dentry
);
2506 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2509 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2512 target
->i_flags
|= S_DEAD
;
2513 mutex_unlock(&target
->i_mutex
);
2514 if (d_unhashed(new_dentry
))
2515 d_rehash(new_dentry
);
2519 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2520 d_move(old_dentry
,new_dentry
);
2524 static int vfs_rename_other(struct inode
*old_dir
, struct dentry
*old_dentry
,
2525 struct inode
*new_dir
, struct dentry
*new_dentry
)
2527 struct inode
*target
;
2530 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2535 target
= new_dentry
->d_inode
;
2537 mutex_lock(&target
->i_mutex
);
2538 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2541 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2543 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2544 d_move(old_dentry
, new_dentry
);
2547 mutex_unlock(&target
->i_mutex
);
2552 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2553 struct inode
*new_dir
, struct dentry
*new_dentry
)
2556 int is_dir
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
2557 const char *old_name
;
2559 if (old_dentry
->d_inode
== new_dentry
->d_inode
)
2562 error
= may_delete(old_dir
, old_dentry
, is_dir
);
2566 if (!new_dentry
->d_inode
)
2567 error
= may_create(new_dir
, new_dentry
, NULL
);
2569 error
= may_delete(new_dir
, new_dentry
, is_dir
);
2573 if (!old_dir
->i_op
|| !old_dir
->i_op
->rename
)
2576 DQUOT_INIT(old_dir
);
2577 DQUOT_INIT(new_dir
);
2579 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
2582 error
= vfs_rename_dir(old_dir
,old_dentry
,new_dir
,new_dentry
);
2584 error
= vfs_rename_other(old_dir
,old_dentry
,new_dir
,new_dentry
);
2586 const char *new_name
= old_dentry
->d_name
.name
;
2587 fsnotify_move(old_dir
, new_dir
, old_name
, new_name
, is_dir
,
2588 new_dentry
->d_inode
, old_dentry
);
2590 fsnotify_oldname_free(old_name
);
2595 static int do_rename(int olddfd
, const char *oldname
,
2596 int newdfd
, const char *newname
)
2599 struct dentry
* old_dir
, * new_dir
;
2600 struct dentry
* old_dentry
, *new_dentry
;
2601 struct dentry
* trap
;
2602 struct nameidata oldnd
, newnd
;
2604 error
= do_path_lookup(olddfd
, oldname
, LOOKUP_PARENT
, &oldnd
);
2608 error
= do_path_lookup(newdfd
, newname
, LOOKUP_PARENT
, &newnd
);
2613 if (oldnd
.path
.mnt
!= newnd
.path
.mnt
)
2616 old_dir
= oldnd
.path
.dentry
;
2618 if (oldnd
.last_type
!= LAST_NORM
)
2621 new_dir
= newnd
.path
.dentry
;
2622 if (newnd
.last_type
!= LAST_NORM
)
2625 trap
= lock_rename(new_dir
, old_dir
);
2627 old_dentry
= lookup_hash(&oldnd
);
2628 error
= PTR_ERR(old_dentry
);
2629 if (IS_ERR(old_dentry
))
2631 /* source must exist */
2633 if (!old_dentry
->d_inode
)
2635 /* unless the source is a directory trailing slashes give -ENOTDIR */
2636 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
)) {
2638 if (oldnd
.last
.name
[oldnd
.last
.len
])
2640 if (newnd
.last
.name
[newnd
.last
.len
])
2643 /* source should not be ancestor of target */
2645 if (old_dentry
== trap
)
2647 new_dentry
= lookup_hash(&newnd
);
2648 error
= PTR_ERR(new_dentry
);
2649 if (IS_ERR(new_dentry
))
2651 /* target should not be an ancestor of source */
2653 if (new_dentry
== trap
)
2656 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
2657 new_dir
->d_inode
, new_dentry
);
2663 unlock_rename(new_dir
, old_dir
);
2665 path_put(&newnd
.path
);
2667 path_put(&oldnd
.path
);
2672 asmlinkage
long sys_renameat(int olddfd
, const char __user
*oldname
,
2673 int newdfd
, const char __user
*newname
)
2679 from
= getname(oldname
);
2681 return PTR_ERR(from
);
2682 to
= getname(newname
);
2683 error
= PTR_ERR(to
);
2685 error
= do_rename(olddfd
, from
, newdfd
, to
);
2692 asmlinkage
long sys_rename(const char __user
*oldname
, const char __user
*newname
)
2694 return sys_renameat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
);
2697 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
, const char *link
)
2701 len
= PTR_ERR(link
);
2706 if (len
> (unsigned) buflen
)
2708 if (copy_to_user(buffer
, link
, len
))
2715 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2716 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2717 * using) it for any given inode is up to filesystem.
2719 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2721 struct nameidata nd
;
2725 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
2726 if (!IS_ERR(cookie
)) {
2727 int res
= vfs_readlink(dentry
, buffer
, buflen
, nd_get_link(&nd
));
2728 if (dentry
->d_inode
->i_op
->put_link
)
2729 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
2730 cookie
= ERR_PTR(res
);
2732 return PTR_ERR(cookie
);
2735 int vfs_follow_link(struct nameidata
*nd
, const char *link
)
2737 return __vfs_follow_link(nd
, link
);
2740 /* get the link contents into pagecache */
2741 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
2744 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
2745 page
= read_mapping_page(mapping
, 0, NULL
);
2752 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2754 struct page
*page
= NULL
;
2755 char *s
= page_getlink(dentry
, &page
);
2756 int res
= vfs_readlink(dentry
,buffer
,buflen
,s
);
2759 page_cache_release(page
);
2764 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
2766 struct page
*page
= NULL
;
2767 nd_set_link(nd
, page_getlink(dentry
, &page
));
2771 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2773 struct page
*page
= cookie
;
2777 page_cache_release(page
);
2781 int __page_symlink(struct inode
*inode
, const char *symname
, int len
,
2784 struct address_space
*mapping
= inode
->i_mapping
;
2791 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
2792 AOP_FLAG_UNINTERRUPTIBLE
, &page
, &fsdata
);
2796 kaddr
= kmap_atomic(page
, KM_USER0
);
2797 memcpy(kaddr
, symname
, len
-1);
2798 kunmap_atomic(kaddr
, KM_USER0
);
2800 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
2807 mark_inode_dirty(inode
);
2813 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
2815 return __page_symlink(inode
, symname
, len
,
2816 mapping_gfp_mask(inode
->i_mapping
));
2819 const struct inode_operations page_symlink_inode_operations
= {
2820 .readlink
= generic_readlink
,
2821 .follow_link
= page_follow_link_light
,
2822 .put_link
= page_put_link
,
2825 EXPORT_SYMBOL(__user_walk
);
2826 EXPORT_SYMBOL(__user_walk_fd
);
2827 EXPORT_SYMBOL(follow_down
);
2828 EXPORT_SYMBOL(follow_up
);
2829 EXPORT_SYMBOL(get_write_access
); /* binfmt_aout */
2830 EXPORT_SYMBOL(getname
);
2831 EXPORT_SYMBOL(lock_rename
);
2832 EXPORT_SYMBOL(lookup_one_len
);
2833 EXPORT_SYMBOL(page_follow_link_light
);
2834 EXPORT_SYMBOL(page_put_link
);
2835 EXPORT_SYMBOL(page_readlink
);
2836 EXPORT_SYMBOL(__page_symlink
);
2837 EXPORT_SYMBOL(page_symlink
);
2838 EXPORT_SYMBOL(page_symlink_inode_operations
);
2839 EXPORT_SYMBOL(path_lookup
);
2840 EXPORT_SYMBOL(vfs_path_lookup
);
2841 EXPORT_SYMBOL(permission
);
2842 EXPORT_SYMBOL(vfs_permission
);
2843 EXPORT_SYMBOL(file_permission
);
2844 EXPORT_SYMBOL(unlock_rename
);
2845 EXPORT_SYMBOL(vfs_create
);
2846 EXPORT_SYMBOL(vfs_follow_link
);
2847 EXPORT_SYMBOL(vfs_link
);
2848 EXPORT_SYMBOL(vfs_mkdir
);
2849 EXPORT_SYMBOL(vfs_mknod
);
2850 EXPORT_SYMBOL(generic_permission
);
2851 EXPORT_SYMBOL(vfs_readlink
);
2852 EXPORT_SYMBOL(vfs_rename
);
2853 EXPORT_SYMBOL(vfs_rmdir
);
2854 EXPORT_SYMBOL(vfs_symlink
);
2855 EXPORT_SYMBOL(vfs_unlink
);
2856 EXPORT_SYMBOL(dentry_unhash
);
2857 EXPORT_SYMBOL(generic_readlink
);