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_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
,
445 struct nameidata
*nd
)
447 umode_t mode
= inode
->i_mode
;
449 if (inode
->i_op
&& inode
->i_op
->permission
)
452 if (current
->fsuid
== inode
->i_uid
)
454 else if (in_group_p(inode
->i_gid
))
460 if ((inode
->i_mode
& S_IXUGO
) && capable(CAP_DAC_OVERRIDE
))
463 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_OVERRIDE
))
466 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_READ_SEARCH
))
471 return security_inode_permission(inode
, MAY_EXEC
, nd
);
475 * This is called when everything else fails, and we actually have
476 * to go to the low-level filesystem to find out what we should do..
478 * We get the directory semaphore, and after getting that we also
479 * make sure that nobody added the entry to the dcache in the meantime..
482 static struct dentry
* real_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
484 struct dentry
* result
;
485 struct inode
*dir
= parent
->d_inode
;
487 mutex_lock(&dir
->i_mutex
);
489 * First re-do the cached lookup just in case it was created
490 * while we waited for the directory semaphore..
492 * FIXME! This could use version numbering or similar to
493 * avoid unnecessary cache lookups.
495 * The "dcache_lock" is purely to protect the RCU list walker
496 * from concurrent renames at this point (we mustn't get false
497 * negatives from the RCU list walk here, unlike the optimistic
500 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
502 result
= d_lookup(parent
, name
);
504 struct dentry
* dentry
= d_alloc(parent
, name
);
505 result
= ERR_PTR(-ENOMEM
);
507 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 int __emul_lookup_dentry(const char *, struct nameidata
*);
533 static __always_inline
int
534 walk_init_root(const char *name
, struct nameidata
*nd
)
536 struct fs_struct
*fs
= current
->fs
;
538 read_lock(&fs
->lock
);
539 if (fs
->altroot
&& !(nd
->flags
& LOOKUP_NOALT
)) {
540 nd
->path
.mnt
= mntget(fs
->altrootmnt
);
541 nd
->path
.dentry
= dget(fs
->altroot
);
542 read_unlock(&fs
->lock
);
543 if (__emul_lookup_dentry(name
,nd
))
545 read_lock(&fs
->lock
);
547 nd
->path
.mnt
= mntget(fs
->rootmnt
);
548 nd
->path
.dentry
= dget(fs
->root
);
549 read_unlock(&fs
->lock
);
553 static __always_inline
int __vfs_follow_link(struct nameidata
*nd
, const char *link
)
562 if (!walk_init_root(link
, nd
))
563 /* weird __emul_prefix() stuff did it */
566 res
= link_path_walk(link
, nd
);
568 if (nd
->depth
|| res
|| nd
->last_type
!=LAST_NORM
)
571 * If it is an iterative symlinks resolution in open_namei() we
572 * have to copy the last component. And all that crap because of
573 * bloody create() on broken symlinks. Furrfu...
576 if (unlikely(!name
)) {
580 strcpy(name
, nd
->last
.name
);
581 nd
->last
.name
= name
;
585 return PTR_ERR(link
);
588 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
591 if (path
->mnt
!= nd
->path
.mnt
)
595 static inline void path_to_nameidata(struct path
*path
, struct nameidata
*nd
)
597 dput(nd
->path
.dentry
);
598 if (nd
->path
.mnt
!= path
->mnt
)
599 mntput(nd
->path
.mnt
);
600 nd
->path
.mnt
= path
->mnt
;
601 nd
->path
.dentry
= path
->dentry
;
604 static __always_inline
int __do_follow_link(struct path
*path
, struct nameidata
*nd
)
608 struct dentry
*dentry
= path
->dentry
;
610 touch_atime(path
->mnt
, dentry
);
611 nd_set_link(nd
, NULL
);
613 if (path
->mnt
!= nd
->path
.mnt
) {
614 path_to_nameidata(path
, nd
);
618 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
619 error
= PTR_ERR(cookie
);
620 if (!IS_ERR(cookie
)) {
621 char *s
= nd_get_link(nd
);
624 error
= __vfs_follow_link(nd
, s
);
625 if (dentry
->d_inode
->i_op
->put_link
)
626 dentry
->d_inode
->i_op
->put_link(dentry
, nd
, cookie
);
634 * This limits recursive symlink follows to 8, while
635 * limiting consecutive symlinks to 40.
637 * Without that kind of total limit, nasty chains of consecutive
638 * symlinks can cause almost arbitrarily long lookups.
640 static inline int do_follow_link(struct path
*path
, struct nameidata
*nd
)
643 if (current
->link_count
>= MAX_NESTED_LINKS
)
645 if (current
->total_link_count
>= 40)
647 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
649 err
= security_inode_follow_link(path
->dentry
, nd
);
652 current
->link_count
++;
653 current
->total_link_count
++;
655 err
= __do_follow_link(path
, nd
);
656 current
->link_count
--;
660 path_put_conditional(path
, nd
);
665 int follow_up(struct vfsmount
**mnt
, struct dentry
**dentry
)
667 struct vfsmount
*parent
;
668 struct dentry
*mountpoint
;
669 spin_lock(&vfsmount_lock
);
670 parent
=(*mnt
)->mnt_parent
;
671 if (parent
== *mnt
) {
672 spin_unlock(&vfsmount_lock
);
676 mountpoint
=dget((*mnt
)->mnt_mountpoint
);
677 spin_unlock(&vfsmount_lock
);
679 *dentry
= mountpoint
;
685 /* no need for dcache_lock, as serialization is taken care in
688 static int __follow_mount(struct path
*path
)
691 while (d_mountpoint(path
->dentry
)) {
692 struct vfsmount
*mounted
= lookup_mnt(path
->mnt
, path
->dentry
);
699 path
->dentry
= dget(mounted
->mnt_root
);
705 static void follow_mount(struct vfsmount
**mnt
, struct dentry
**dentry
)
707 while (d_mountpoint(*dentry
)) {
708 struct vfsmount
*mounted
= lookup_mnt(*mnt
, *dentry
);
714 *dentry
= dget(mounted
->mnt_root
);
718 /* no need for dcache_lock, as serialization is taken care in
721 int follow_down(struct vfsmount
**mnt
, struct dentry
**dentry
)
723 struct vfsmount
*mounted
;
725 mounted
= lookup_mnt(*mnt
, *dentry
);
730 *dentry
= dget(mounted
->mnt_root
);
736 static __always_inline
void follow_dotdot(struct nameidata
*nd
)
738 struct fs_struct
*fs
= current
->fs
;
741 struct vfsmount
*parent
;
742 struct dentry
*old
= nd
->path
.dentry
;
744 read_lock(&fs
->lock
);
745 if (nd
->path
.dentry
== fs
->root
&&
746 nd
->path
.mnt
== fs
->rootmnt
) {
747 read_unlock(&fs
->lock
);
750 read_unlock(&fs
->lock
);
751 spin_lock(&dcache_lock
);
752 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
753 nd
->path
.dentry
= dget(nd
->path
.dentry
->d_parent
);
754 spin_unlock(&dcache_lock
);
758 spin_unlock(&dcache_lock
);
759 spin_lock(&vfsmount_lock
);
760 parent
= nd
->path
.mnt
->mnt_parent
;
761 if (parent
== nd
->path
.mnt
) {
762 spin_unlock(&vfsmount_lock
);
766 nd
->path
.dentry
= dget(nd
->path
.mnt
->mnt_mountpoint
);
767 spin_unlock(&vfsmount_lock
);
769 mntput(nd
->path
.mnt
);
770 nd
->path
.mnt
= parent
;
772 follow_mount(&nd
->path
.mnt
, &nd
->path
.dentry
);
776 * It's more convoluted than I'd like it to be, but... it's still fairly
777 * small and for now I'd prefer to have fast path as straight as possible.
778 * It _is_ time-critical.
780 static int do_lookup(struct nameidata
*nd
, struct qstr
*name
,
783 struct vfsmount
*mnt
= nd
->path
.mnt
;
784 struct dentry
*dentry
= __d_lookup(nd
->path
.dentry
, name
);
788 if (dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
789 goto need_revalidate
;
792 path
->dentry
= dentry
;
793 __follow_mount(path
);
797 dentry
= real_lookup(nd
->path
.dentry
, name
, nd
);
803 dentry
= do_revalidate(dentry
, nd
);
811 return PTR_ERR(dentry
);
816 * This is the basic name resolution function, turning a pathname into
817 * the final dentry. We expect 'base' to be positive and a directory.
819 * Returns 0 and nd will have valid dentry and mnt on success.
820 * Returns error and drops reference to input namei data on failure.
822 static int __link_path_walk(const char *name
, struct nameidata
*nd
)
827 unsigned int lookup_flags
= nd
->flags
;
834 inode
= nd
->path
.dentry
->d_inode
;
836 lookup_flags
= LOOKUP_FOLLOW
| (nd
->flags
& LOOKUP_CONTINUE
);
838 /* At this point we know we have a real path component. */
844 nd
->flags
|= LOOKUP_CONTINUE
;
845 err
= exec_permission_lite(inode
, nd
);
847 err
= vfs_permission(nd
, MAY_EXEC
);
852 c
= *(const unsigned char *)name
;
854 hash
= init_name_hash();
857 hash
= partial_name_hash(c
, hash
);
858 c
= *(const unsigned char *)name
;
859 } while (c
&& (c
!= '/'));
860 this.len
= name
- (const char *) this.name
;
861 this.hash
= end_name_hash(hash
);
863 /* remove trailing slashes? */
866 while (*++name
== '/');
868 goto last_with_slashes
;
871 * "." and ".." are special - ".." especially so because it has
872 * to be able to know about the current root directory and
873 * parent relationships.
875 if (this.name
[0] == '.') switch (this.len
) {
879 if (this.name
[1] != '.')
882 inode
= nd
->path
.dentry
->d_inode
;
888 * See if the low-level filesystem might want
889 * to use its own hash..
891 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
892 err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
897 /* This does the actual lookups.. */
898 err
= do_lookup(nd
, &this, &next
);
903 inode
= next
.dentry
->d_inode
;
910 if (inode
->i_op
->follow_link
) {
911 err
= do_follow_link(&next
, nd
);
915 inode
= nd
->path
.dentry
->d_inode
;
922 path_to_nameidata(&next
, nd
);
924 if (!inode
->i_op
->lookup
)
927 /* here ends the main loop */
930 lookup_flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
932 /* Clear LOOKUP_CONTINUE iff it was previously unset */
933 nd
->flags
&= lookup_flags
| ~LOOKUP_CONTINUE
;
934 if (lookup_flags
& LOOKUP_PARENT
)
936 if (this.name
[0] == '.') switch (this.len
) {
940 if (this.name
[1] != '.')
943 inode
= nd
->path
.dentry
->d_inode
;
948 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
949 err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
954 err
= do_lookup(nd
, &this, &next
);
957 inode
= next
.dentry
->d_inode
;
958 if ((lookup_flags
& LOOKUP_FOLLOW
)
959 && inode
&& inode
->i_op
&& inode
->i_op
->follow_link
) {
960 err
= do_follow_link(&next
, nd
);
963 inode
= nd
->path
.dentry
->d_inode
;
965 path_to_nameidata(&next
, nd
);
969 if (lookup_flags
& LOOKUP_DIRECTORY
) {
971 if (!inode
->i_op
|| !inode
->i_op
->lookup
)
977 nd
->last_type
= LAST_NORM
;
978 if (this.name
[0] != '.')
981 nd
->last_type
= LAST_DOT
;
982 else if (this.len
== 2 && this.name
[1] == '.')
983 nd
->last_type
= LAST_DOTDOT
;
988 * We bypassed the ordinary revalidation routines.
989 * We may need to check the cached dentry for staleness.
991 if (nd
->path
.dentry
&& nd
->path
.dentry
->d_sb
&&
992 (nd
->path
.dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
)) {
994 /* Note: we do not d_invalidate() */
995 if (!nd
->path
.dentry
->d_op
->d_revalidate(
996 nd
->path
.dentry
, nd
))
1002 path_put_conditional(&next
, nd
);
1005 path_put(&nd
->path
);
1011 * Wrapper to retry pathname resolution whenever the underlying
1012 * file system returns an ESTALE.
1014 * Retry the whole path once, forcing real lookup requests
1015 * instead of relying on the dcache.
1017 static int link_path_walk(const char *name
, struct nameidata
*nd
)
1019 struct nameidata save
= *nd
;
1022 /* make sure the stuff we saved doesn't go away */
1023 dget(save
.path
.dentry
);
1024 mntget(save
.path
.mnt
);
1026 result
= __link_path_walk(name
, nd
);
1027 if (result
== -ESTALE
) {
1029 dget(nd
->path
.dentry
);
1030 mntget(nd
->path
.mnt
);
1031 nd
->flags
|= LOOKUP_REVAL
;
1032 result
= __link_path_walk(name
, nd
);
1035 path_put(&save
.path
);
1040 static int path_walk(const char *name
, struct nameidata
*nd
)
1042 current
->total_link_count
= 0;
1043 return link_path_walk(name
, nd
);
1047 * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
1048 * everything is done. Returns 0 and drops input nd, if lookup failed;
1050 static int __emul_lookup_dentry(const char *name
, struct nameidata
*nd
)
1052 if (path_walk(name
, nd
))
1053 return 0; /* something went wrong... */
1055 if (!nd
->path
.dentry
->d_inode
||
1056 S_ISDIR(nd
->path
.dentry
->d_inode
->i_mode
)) {
1057 struct path old_path
= nd
->path
;
1058 struct qstr last
= nd
->last
;
1059 int last_type
= nd
->last_type
;
1060 struct fs_struct
*fs
= current
->fs
;
1063 * NAME was not found in alternate root or it's a directory.
1064 * Try to find it in the normal root:
1066 nd
->last_type
= LAST_ROOT
;
1067 read_lock(&fs
->lock
);
1068 nd
->path
.mnt
= mntget(fs
->rootmnt
);
1069 nd
->path
.dentry
= dget(fs
->root
);
1070 read_unlock(&fs
->lock
);
1071 if (path_walk(name
, nd
) == 0) {
1072 if (nd
->path
.dentry
->d_inode
) {
1073 path_put(&old_path
);
1076 path_put(&nd
->path
);
1078 nd
->path
= old_path
;
1080 nd
->last_type
= last_type
;
1085 void set_fs_altroot(void)
1087 char *emul
= __emul_prefix();
1088 struct nameidata nd
;
1089 struct vfsmount
*mnt
= NULL
, *oldmnt
;
1090 struct dentry
*dentry
= NULL
, *olddentry
;
1092 struct fs_struct
*fs
= current
->fs
;
1096 err
= path_lookup(emul
, LOOKUP_FOLLOW
|LOOKUP_DIRECTORY
|LOOKUP_NOALT
, &nd
);
1099 dentry
= nd
.path
.dentry
;
1102 write_lock(&fs
->lock
);
1103 oldmnt
= fs
->altrootmnt
;
1104 olddentry
= fs
->altroot
;
1105 fs
->altrootmnt
= mnt
;
1106 fs
->altroot
= dentry
;
1107 write_unlock(&fs
->lock
);
1114 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1115 static int do_path_lookup(int dfd
, const char *name
,
1116 unsigned int flags
, struct nameidata
*nd
)
1121 struct fs_struct
*fs
= current
->fs
;
1123 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1128 read_lock(&fs
->lock
);
1129 if (fs
->altroot
&& !(nd
->flags
& LOOKUP_NOALT
)) {
1130 nd
->path
.mnt
= mntget(fs
->altrootmnt
);
1131 nd
->path
.dentry
= dget(fs
->altroot
);
1132 read_unlock(&fs
->lock
);
1133 if (__emul_lookup_dentry(name
,nd
))
1134 goto out
; /* found in altroot */
1135 read_lock(&fs
->lock
);
1137 nd
->path
.mnt
= mntget(fs
->rootmnt
);
1138 nd
->path
.dentry
= dget(fs
->root
);
1139 read_unlock(&fs
->lock
);
1140 } else if (dfd
== AT_FDCWD
) {
1141 read_lock(&fs
->lock
);
1142 nd
->path
.mnt
= mntget(fs
->pwdmnt
);
1143 nd
->path
.dentry
= dget(fs
->pwd
);
1144 read_unlock(&fs
->lock
);
1146 struct dentry
*dentry
;
1148 file
= fget_light(dfd
, &fput_needed
);
1153 dentry
= file
->f_path
.dentry
;
1156 if (!S_ISDIR(dentry
->d_inode
->i_mode
))
1159 retval
= file_permission(file
, MAY_EXEC
);
1163 nd
->path
.mnt
= mntget(file
->f_path
.mnt
);
1164 nd
->path
.dentry
= dget(dentry
);
1166 fput_light(file
, fput_needed
);
1169 retval
= path_walk(name
, nd
);
1171 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1172 nd
->path
.dentry
->d_inode
))
1173 audit_inode(name
, nd
->path
.dentry
);
1178 fput_light(file
, fput_needed
);
1182 int path_lookup(const char *name
, unsigned int flags
,
1183 struct nameidata
*nd
)
1185 return do_path_lookup(AT_FDCWD
, name
, flags
, nd
);
1189 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1190 * @dentry: pointer to dentry of the base directory
1191 * @mnt: pointer to vfs mount of the base directory
1192 * @name: pointer to file name
1193 * @flags: lookup flags
1194 * @nd: pointer to nameidata
1196 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
1197 const char *name
, unsigned int flags
,
1198 struct nameidata
*nd
)
1202 /* same as do_path_lookup */
1203 nd
->last_type
= LAST_ROOT
;
1207 nd
->path
.mnt
= mntget(mnt
);
1208 nd
->path
.dentry
= dget(dentry
);
1210 retval
= path_walk(name
, nd
);
1211 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1212 nd
->path
.dentry
->d_inode
))
1213 audit_inode(name
, nd
->path
.dentry
);
1219 static int __path_lookup_intent_open(int dfd
, const char *name
,
1220 unsigned int lookup_flags
, struct nameidata
*nd
,
1221 int open_flags
, int create_mode
)
1223 struct file
*filp
= get_empty_filp();
1228 nd
->intent
.open
.file
= filp
;
1229 nd
->intent
.open
.flags
= open_flags
;
1230 nd
->intent
.open
.create_mode
= create_mode
;
1231 err
= do_path_lookup(dfd
, name
, lookup_flags
|LOOKUP_OPEN
, nd
);
1232 if (IS_ERR(nd
->intent
.open
.file
)) {
1234 err
= PTR_ERR(nd
->intent
.open
.file
);
1235 path_put(&nd
->path
);
1237 } else if (err
!= 0)
1238 release_open_intent(nd
);
1243 * path_lookup_open - lookup a file path with open intent
1244 * @dfd: the directory to use as base, or AT_FDCWD
1245 * @name: pointer to file name
1246 * @lookup_flags: lookup intent flags
1247 * @nd: pointer to nameidata
1248 * @open_flags: open intent flags
1250 int path_lookup_open(int dfd
, const char *name
, unsigned int lookup_flags
,
1251 struct nameidata
*nd
, int open_flags
)
1253 return __path_lookup_intent_open(dfd
, name
, lookup_flags
, nd
,
1258 * path_lookup_create - lookup a file path with open + create 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
1264 * @create_mode: create intent flags
1266 static int path_lookup_create(int dfd
, const char *name
,
1267 unsigned int lookup_flags
, struct nameidata
*nd
,
1268 int open_flags
, int create_mode
)
1270 return __path_lookup_intent_open(dfd
, name
, lookup_flags
|LOOKUP_CREATE
,
1271 nd
, open_flags
, create_mode
);
1274 int __user_path_lookup_open(const char __user
*name
, unsigned int lookup_flags
,
1275 struct nameidata
*nd
, int open_flags
)
1277 char *tmp
= getname(name
);
1278 int err
= PTR_ERR(tmp
);
1281 err
= __path_lookup_intent_open(AT_FDCWD
, tmp
, lookup_flags
, nd
, open_flags
, 0);
1287 static struct dentry
*__lookup_hash(struct qstr
*name
,
1288 struct dentry
*base
, struct nameidata
*nd
)
1290 struct dentry
*dentry
;
1291 struct inode
*inode
;
1294 inode
= base
->d_inode
;
1297 * See if the low-level filesystem might want
1298 * to use its own hash..
1300 if (base
->d_op
&& base
->d_op
->d_hash
) {
1301 err
= base
->d_op
->d_hash(base
, name
);
1302 dentry
= ERR_PTR(err
);
1307 dentry
= cached_lookup(base
, name
, nd
);
1309 struct dentry
*new = d_alloc(base
, name
);
1310 dentry
= ERR_PTR(-ENOMEM
);
1313 dentry
= inode
->i_op
->lookup(inode
, new, nd
);
1324 * Restricted form of lookup. Doesn't follow links, single-component only,
1325 * needs parent already locked. Doesn't follow mounts.
1328 static struct dentry
*lookup_hash(struct nameidata
*nd
)
1332 err
= permission(nd
->path
.dentry
->d_inode
, MAY_EXEC
, nd
);
1334 return ERR_PTR(err
);
1335 return __lookup_hash(&nd
->last
, nd
->path
.dentry
, nd
);
1338 static int __lookup_one_len(const char *name
, struct qstr
*this,
1339 struct dentry
*base
, int len
)
1349 hash
= init_name_hash();
1351 c
= *(const unsigned char *)name
++;
1352 if (c
== '/' || c
== '\0')
1354 hash
= partial_name_hash(c
, hash
);
1356 this->hash
= end_name_hash(hash
);
1361 * lookup_one_len: filesystem helper to lookup single pathname component
1362 * @name: pathname component to lookup
1363 * @base: base directory to lookup from
1364 * @len: maximum length @len should be interpreted to
1366 * Note that this routine is purely a helper for filesystem useage and should
1367 * not be called by generic code. Also note that by using this function to
1368 * nameidata argument is passed to the filesystem methods and a filesystem
1369 * using this helper needs to be prepared for that.
1371 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
1376 err
= __lookup_one_len(name
, &this, base
, len
);
1378 return ERR_PTR(err
);
1380 err
= permission(base
->d_inode
, MAY_EXEC
, NULL
);
1382 return ERR_PTR(err
);
1383 return __lookup_hash(&this, base
, NULL
);
1387 * lookup_one_noperm - bad hack for sysfs
1388 * @name: pathname component to lookup
1389 * @base: base directory to lookup from
1391 * This is a variant of lookup_one_len that doesn't perform any permission
1392 * checks. It's a horrible hack to work around the braindead sysfs
1393 * architecture and should not be used anywhere else.
1395 * DON'T USE THIS FUNCTION EVER, thanks.
1397 struct dentry
*lookup_one_noperm(const char *name
, struct dentry
*base
)
1402 err
= __lookup_one_len(name
, &this, base
, strlen(name
));
1404 return ERR_PTR(err
);
1405 return __lookup_hash(&this, base
, NULL
);
1408 int __user_walk_fd(int dfd
, const char __user
*name
, unsigned flags
,
1409 struct nameidata
*nd
)
1411 char *tmp
= getname(name
);
1412 int err
= PTR_ERR(tmp
);
1415 err
= do_path_lookup(dfd
, tmp
, flags
, nd
);
1421 int __user_walk(const char __user
*name
, unsigned flags
, struct nameidata
*nd
)
1423 return __user_walk_fd(AT_FDCWD
, name
, flags
, nd
);
1427 * It's inline, so penalty for filesystems that don't use sticky bit is
1430 static inline int check_sticky(struct inode
*dir
, struct inode
*inode
)
1432 if (!(dir
->i_mode
& S_ISVTX
))
1434 if (inode
->i_uid
== current
->fsuid
)
1436 if (dir
->i_uid
== current
->fsuid
)
1438 return !capable(CAP_FOWNER
);
1442 * Check whether we can remove a link victim from directory dir, check
1443 * whether the type of victim is right.
1444 * 1. We can't do it if dir is read-only (done in permission())
1445 * 2. We should have write and exec permissions on dir
1446 * 3. We can't remove anything from append-only dir
1447 * 4. We can't do anything with immutable dir (done in permission())
1448 * 5. If the sticky bit on dir is set we should either
1449 * a. be owner of dir, or
1450 * b. be owner of victim, or
1451 * c. have CAP_FOWNER capability
1452 * 6. If the victim is append-only or immutable we can't do antyhing with
1453 * links pointing to it.
1454 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1455 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1456 * 9. We can't remove a root or mountpoint.
1457 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1458 * nfs_async_unlink().
1460 static int may_delete(struct inode
*dir
,struct dentry
*victim
,int isdir
)
1464 if (!victim
->d_inode
)
1467 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
1468 audit_inode_child(victim
->d_name
.name
, victim
, dir
);
1470 error
= permission(dir
,MAY_WRITE
| MAY_EXEC
, NULL
);
1475 if (check_sticky(dir
, victim
->d_inode
)||IS_APPEND(victim
->d_inode
)||
1476 IS_IMMUTABLE(victim
->d_inode
))
1479 if (!S_ISDIR(victim
->d_inode
->i_mode
))
1481 if (IS_ROOT(victim
))
1483 } else if (S_ISDIR(victim
->d_inode
->i_mode
))
1485 if (IS_DEADDIR(dir
))
1487 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
1492 /* Check whether we can create an object with dentry child in directory
1494 * 1. We can't do it if child already exists (open has special treatment for
1495 * this case, but since we are inlined it's OK)
1496 * 2. We can't do it if dir is read-only (done in permission())
1497 * 3. We should have write and exec permissions on dir
1498 * 4. We can't do it if dir is immutable (done in permission())
1500 static inline int may_create(struct inode
*dir
, struct dentry
*child
,
1501 struct nameidata
*nd
)
1505 if (IS_DEADDIR(dir
))
1507 return permission(dir
,MAY_WRITE
| MAY_EXEC
, nd
);
1511 * O_DIRECTORY translates into forcing a directory lookup.
1513 static inline int lookup_flags(unsigned int f
)
1515 unsigned long retval
= LOOKUP_FOLLOW
;
1518 retval
&= ~LOOKUP_FOLLOW
;
1520 if (f
& O_DIRECTORY
)
1521 retval
|= LOOKUP_DIRECTORY
;
1527 * p1 and p2 should be directories on the same fs.
1529 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
1534 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1538 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1540 for (p
= p1
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1541 if (p
->d_parent
== p2
) {
1542 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1543 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1548 for (p
= p2
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1549 if (p
->d_parent
== p1
) {
1550 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1551 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1556 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1557 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1561 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
1563 mutex_unlock(&p1
->d_inode
->i_mutex
);
1565 mutex_unlock(&p2
->d_inode
->i_mutex
);
1566 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1570 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1571 struct nameidata
*nd
)
1573 int error
= may_create(dir
, dentry
, nd
);
1578 if (!dir
->i_op
|| !dir
->i_op
->create
)
1579 return -EACCES
; /* shouldn't it be ENOSYS? */
1582 error
= security_inode_create(dir
, dentry
, mode
);
1586 error
= dir
->i_op
->create(dir
, dentry
, mode
, nd
);
1588 fsnotify_create(dir
, dentry
);
1592 int may_open(struct nameidata
*nd
, int acc_mode
, int flag
)
1594 struct dentry
*dentry
= nd
->path
.dentry
;
1595 struct inode
*inode
= dentry
->d_inode
;
1601 if (S_ISLNK(inode
->i_mode
))
1604 if (S_ISDIR(inode
->i_mode
) && (acc_mode
& MAY_WRITE
))
1608 * FIFO's, sockets and device files are special: they don't
1609 * actually live on the filesystem itself, and as such you
1610 * can write to them even if the filesystem is read-only.
1612 if (S_ISFIFO(inode
->i_mode
) || S_ISSOCK(inode
->i_mode
)) {
1614 } else if (S_ISBLK(inode
->i_mode
) || S_ISCHR(inode
->i_mode
)) {
1615 if (nd
->path
.mnt
->mnt_flags
& MNT_NODEV
)
1619 } else if (IS_RDONLY(inode
) && (acc_mode
& MAY_WRITE
))
1622 error
= vfs_permission(nd
, acc_mode
);
1626 * An append-only file must be opened in append mode for writing.
1628 if (IS_APPEND(inode
)) {
1629 if ((flag
& FMODE_WRITE
) && !(flag
& O_APPEND
))
1635 /* O_NOATIME can only be set by the owner or superuser */
1636 if (flag
& O_NOATIME
)
1637 if (!is_owner_or_cap(inode
))
1641 * Ensure there are no outstanding leases on the file.
1643 error
= break_lease(inode
, flag
);
1647 if (flag
& O_TRUNC
) {
1648 error
= get_write_access(inode
);
1653 * Refuse to truncate files with mandatory locks held on them.
1655 error
= locks_verify_locked(inode
);
1659 error
= do_truncate(dentry
, 0,
1660 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
1663 put_write_access(inode
);
1667 if (flag
& FMODE_WRITE
)
1673 static int open_namei_create(struct nameidata
*nd
, struct path
*path
,
1677 struct dentry
*dir
= nd
->path
.dentry
;
1679 if (!IS_POSIXACL(dir
->d_inode
))
1680 mode
&= ~current
->fs
->umask
;
1681 error
= vfs_create(dir
->d_inode
, path
->dentry
, mode
, nd
);
1682 mutex_unlock(&dir
->d_inode
->i_mutex
);
1683 dput(nd
->path
.dentry
);
1684 nd
->path
.dentry
= path
->dentry
;
1687 /* Don't check for write permission, don't truncate */
1688 return may_open(nd
, 0, flag
& ~O_TRUNC
);
1694 * namei for open - this is in fact almost the whole open-routine.
1696 * Note that the low bits of "flag" aren't the same as in the open
1697 * system call - they are 00 - no permissions needed
1698 * 01 - read permission needed
1699 * 10 - write permission needed
1700 * 11 - read/write permissions needed
1701 * which is a lot more logical, and also allows the "no perm" needed
1702 * for symlinks (where the permissions are checked later).
1705 int open_namei(int dfd
, const char *pathname
, int flag
,
1706 int mode
, struct nameidata
*nd
)
1708 int acc_mode
, error
;
1713 acc_mode
= ACC_MODE(flag
);
1715 /* O_TRUNC implies we need access checks for write permissions */
1717 acc_mode
|= MAY_WRITE
;
1719 /* Allow the LSM permission hook to distinguish append
1720 access from general write access. */
1721 if (flag
& O_APPEND
)
1722 acc_mode
|= MAY_APPEND
;
1725 * The simplest case - just a plain lookup.
1727 if (!(flag
& O_CREAT
)) {
1728 error
= path_lookup_open(dfd
, pathname
, lookup_flags(flag
),
1736 * Create - we need to know the parent.
1738 error
= path_lookup_create(dfd
,pathname
,LOOKUP_PARENT
,nd
,flag
,mode
);
1743 * We have the parent and last component. First of all, check
1744 * that we are not asked to creat(2) an obvious directory - that
1748 if (nd
->last_type
!= LAST_NORM
|| nd
->last
.name
[nd
->last
.len
])
1751 dir
= nd
->path
.dentry
;
1752 nd
->flags
&= ~LOOKUP_PARENT
;
1753 mutex_lock(&dir
->d_inode
->i_mutex
);
1754 path
.dentry
= lookup_hash(nd
);
1755 path
.mnt
= nd
->path
.mnt
;
1758 error
= PTR_ERR(path
.dentry
);
1759 if (IS_ERR(path
.dentry
)) {
1760 mutex_unlock(&dir
->d_inode
->i_mutex
);
1764 if (IS_ERR(nd
->intent
.open
.file
)) {
1765 mutex_unlock(&dir
->d_inode
->i_mutex
);
1766 error
= PTR_ERR(nd
->intent
.open
.file
);
1770 /* Negative dentry, just create the file */
1771 if (!path
.dentry
->d_inode
) {
1772 error
= open_namei_create(nd
, &path
, flag
, mode
);
1779 * It already exists.
1781 mutex_unlock(&dir
->d_inode
->i_mutex
);
1782 audit_inode(pathname
, path
.dentry
);
1788 if (__follow_mount(&path
)) {
1790 if (flag
& O_NOFOLLOW
)
1795 if (!path
.dentry
->d_inode
)
1797 if (path
.dentry
->d_inode
->i_op
&& path
.dentry
->d_inode
->i_op
->follow_link
)
1800 path_to_nameidata(&path
, nd
);
1802 if (path
.dentry
->d_inode
&& S_ISDIR(path
.dentry
->d_inode
->i_mode
))
1805 error
= may_open(nd
, acc_mode
, flag
);
1811 path_put_conditional(&path
, nd
);
1813 if (!IS_ERR(nd
->intent
.open
.file
))
1814 release_open_intent(nd
);
1815 path_put(&nd
->path
);
1820 if (flag
& O_NOFOLLOW
)
1823 * This is subtle. Instead of calling do_follow_link() we do the
1824 * thing by hands. The reason is that this way we have zero link_count
1825 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1826 * After that we have the parent and last component, i.e.
1827 * we are in the same situation as after the first path_walk().
1828 * Well, almost - if the last component is normal we get its copy
1829 * stored in nd->last.name and we will have to putname() it when we
1830 * are done. Procfs-like symlinks just set LAST_BIND.
1832 nd
->flags
|= LOOKUP_PARENT
;
1833 error
= security_inode_follow_link(path
.dentry
, nd
);
1836 error
= __do_follow_link(&path
, nd
);
1838 /* Does someone understand code flow here? Or it is only
1839 * me so stupid? Anathema to whoever designed this non-sense
1840 * with "intent.open".
1842 release_open_intent(nd
);
1845 nd
->flags
&= ~LOOKUP_PARENT
;
1846 if (nd
->last_type
== LAST_BIND
)
1849 if (nd
->last_type
!= LAST_NORM
)
1851 if (nd
->last
.name
[nd
->last
.len
]) {
1852 __putname(nd
->last
.name
);
1857 __putname(nd
->last
.name
);
1860 dir
= nd
->path
.dentry
;
1861 mutex_lock(&dir
->d_inode
->i_mutex
);
1862 path
.dentry
= lookup_hash(nd
);
1863 path
.mnt
= nd
->path
.mnt
;
1864 __putname(nd
->last
.name
);
1869 * lookup_create - lookup a dentry, creating it if it doesn't exist
1870 * @nd: nameidata info
1871 * @is_dir: directory flag
1873 * Simple function to lookup and return a dentry and create it
1874 * if it doesn't exist. Is SMP-safe.
1876 * Returns with nd->path.dentry->d_inode->i_mutex locked.
1878 struct dentry
*lookup_create(struct nameidata
*nd
, int is_dir
)
1880 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
1882 mutex_lock_nested(&nd
->path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1884 * Yucky last component or no last component at all?
1885 * (foo/., foo/.., /////)
1887 if (nd
->last_type
!= LAST_NORM
)
1889 nd
->flags
&= ~LOOKUP_PARENT
;
1890 nd
->flags
|= LOOKUP_CREATE
;
1891 nd
->intent
.open
.flags
= O_EXCL
;
1894 * Do the final lookup.
1896 dentry
= lookup_hash(nd
);
1901 * Special case - lookup gave negative, but... we had foo/bar/
1902 * From the vfs_mknod() POV we just have a negative dentry -
1903 * all is fine. Let's be bastards - you had / on the end, you've
1904 * been asking for (non-existent) directory. -ENOENT for you.
1906 if (!is_dir
&& nd
->last
.name
[nd
->last
.len
] && !dentry
->d_inode
)
1911 dentry
= ERR_PTR(-ENOENT
);
1915 EXPORT_SYMBOL_GPL(lookup_create
);
1917 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1919 int error
= may_create(dir
, dentry
, NULL
);
1924 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
1927 if (!dir
->i_op
|| !dir
->i_op
->mknod
)
1930 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
1935 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
1937 fsnotify_create(dir
, dentry
);
1941 asmlinkage
long sys_mknodat(int dfd
, const char __user
*filename
, int mode
,
1946 struct dentry
* dentry
;
1947 struct nameidata nd
;
1951 tmp
= getname(filename
);
1953 return PTR_ERR(tmp
);
1955 error
= do_path_lookup(dfd
, tmp
, LOOKUP_PARENT
, &nd
);
1958 dentry
= lookup_create(&nd
, 0);
1959 error
= PTR_ERR(dentry
);
1961 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
1962 mode
&= ~current
->fs
->umask
;
1963 if (!IS_ERR(dentry
)) {
1964 switch (mode
& S_IFMT
) {
1965 case 0: case S_IFREG
:
1966 error
= vfs_create(nd
.path
.dentry
->d_inode
,dentry
,mode
,&nd
);
1968 case S_IFCHR
: case S_IFBLK
:
1969 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,
1970 new_decode_dev(dev
));
1972 case S_IFIFO
: case S_IFSOCK
:
1973 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,0);
1983 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
1991 asmlinkage
long sys_mknod(const char __user
*filename
, int mode
, unsigned dev
)
1993 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
1996 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
1998 int error
= may_create(dir
, dentry
, NULL
);
2003 if (!dir
->i_op
|| !dir
->i_op
->mkdir
)
2006 mode
&= (S_IRWXUGO
|S_ISVTX
);
2007 error
= security_inode_mkdir(dir
, dentry
, mode
);
2012 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
2014 fsnotify_mkdir(dir
, dentry
);
2018 asmlinkage
long sys_mkdirat(int dfd
, const char __user
*pathname
, int mode
)
2022 struct dentry
*dentry
;
2023 struct nameidata nd
;
2025 tmp
= getname(pathname
);
2026 error
= PTR_ERR(tmp
);
2030 error
= do_path_lookup(dfd
, tmp
, LOOKUP_PARENT
, &nd
);
2033 dentry
= lookup_create(&nd
, 1);
2034 error
= PTR_ERR(dentry
);
2038 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2039 mode
&= ~current
->fs
->umask
;
2040 error
= vfs_mkdir(nd
.path
.dentry
->d_inode
, dentry
, mode
);
2043 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2051 asmlinkage
long sys_mkdir(const char __user
*pathname
, int mode
)
2053 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
2057 * We try to drop the dentry early: we should have
2058 * a usage count of 2 if we're the only user of this
2059 * dentry, and if that is true (possibly after pruning
2060 * the dcache), then we drop the dentry now.
2062 * A low-level filesystem can, if it choses, legally
2065 * if (!d_unhashed(dentry))
2068 * if it cannot handle the case of removing a directory
2069 * that is still in use by something else..
2071 void dentry_unhash(struct dentry
*dentry
)
2074 shrink_dcache_parent(dentry
);
2075 spin_lock(&dcache_lock
);
2076 spin_lock(&dentry
->d_lock
);
2077 if (atomic_read(&dentry
->d_count
) == 2)
2079 spin_unlock(&dentry
->d_lock
);
2080 spin_unlock(&dcache_lock
);
2083 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2085 int error
= may_delete(dir
, dentry
, 1);
2090 if (!dir
->i_op
|| !dir
->i_op
->rmdir
)
2095 mutex_lock(&dentry
->d_inode
->i_mutex
);
2096 dentry_unhash(dentry
);
2097 if (d_mountpoint(dentry
))
2100 error
= security_inode_rmdir(dir
, dentry
);
2102 error
= dir
->i_op
->rmdir(dir
, dentry
);
2104 dentry
->d_inode
->i_flags
|= S_DEAD
;
2107 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2116 static long do_rmdir(int dfd
, const char __user
*pathname
)
2120 struct dentry
*dentry
;
2121 struct nameidata nd
;
2123 name
= getname(pathname
);
2125 return PTR_ERR(name
);
2127 error
= do_path_lookup(dfd
, name
, LOOKUP_PARENT
, &nd
);
2131 switch(nd
.last_type
) {
2142 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2143 dentry
= lookup_hash(&nd
);
2144 error
= PTR_ERR(dentry
);
2147 error
= vfs_rmdir(nd
.path
.dentry
->d_inode
, dentry
);
2150 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2158 asmlinkage
long sys_rmdir(const char __user
*pathname
)
2160 return do_rmdir(AT_FDCWD
, pathname
);
2163 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
)
2165 int error
= may_delete(dir
, dentry
, 0);
2170 if (!dir
->i_op
|| !dir
->i_op
->unlink
)
2175 mutex_lock(&dentry
->d_inode
->i_mutex
);
2176 if (d_mountpoint(dentry
))
2179 error
= security_inode_unlink(dir
, dentry
);
2181 error
= dir
->i_op
->unlink(dir
, dentry
);
2183 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2185 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2186 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
2187 fsnotify_link_count(dentry
->d_inode
);
2195 * Make sure that the actual truncation of the file will occur outside its
2196 * directory's i_mutex. Truncate can take a long time if there is a lot of
2197 * writeout happening, and we don't want to prevent access to the directory
2198 * while waiting on the I/O.
2200 static long do_unlinkat(int dfd
, const char __user
*pathname
)
2204 struct dentry
*dentry
;
2205 struct nameidata nd
;
2206 struct inode
*inode
= NULL
;
2208 name
= getname(pathname
);
2210 return PTR_ERR(name
);
2212 error
= do_path_lookup(dfd
, name
, LOOKUP_PARENT
, &nd
);
2216 if (nd
.last_type
!= LAST_NORM
)
2218 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2219 dentry
= lookup_hash(&nd
);
2220 error
= PTR_ERR(dentry
);
2221 if (!IS_ERR(dentry
)) {
2222 /* Why not before? Because we want correct error value */
2223 if (nd
.last
.name
[nd
.last
.len
])
2225 inode
= dentry
->d_inode
;
2227 atomic_inc(&inode
->i_count
);
2228 error
= vfs_unlink(nd
.path
.dentry
->d_inode
, dentry
);
2232 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2234 iput(inode
); /* truncate the inode here */
2242 error
= !dentry
->d_inode
? -ENOENT
:
2243 S_ISDIR(dentry
->d_inode
->i_mode
) ? -EISDIR
: -ENOTDIR
;
2247 asmlinkage
long sys_unlinkat(int dfd
, const char __user
*pathname
, int flag
)
2249 if ((flag
& ~AT_REMOVEDIR
) != 0)
2252 if (flag
& AT_REMOVEDIR
)
2253 return do_rmdir(dfd
, pathname
);
2255 return do_unlinkat(dfd
, pathname
);
2258 asmlinkage
long sys_unlink(const char __user
*pathname
)
2260 return do_unlinkat(AT_FDCWD
, pathname
);
2263 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
, int mode
)
2265 int error
= may_create(dir
, dentry
, NULL
);
2270 if (!dir
->i_op
|| !dir
->i_op
->symlink
)
2273 error
= security_inode_symlink(dir
, dentry
, oldname
);
2278 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
2280 fsnotify_create(dir
, dentry
);
2284 asmlinkage
long sys_symlinkat(const char __user
*oldname
,
2285 int newdfd
, const char __user
*newname
)
2290 struct dentry
*dentry
;
2291 struct nameidata nd
;
2293 from
= getname(oldname
);
2295 return PTR_ERR(from
);
2296 to
= getname(newname
);
2297 error
= PTR_ERR(to
);
2301 error
= do_path_lookup(newdfd
, to
, LOOKUP_PARENT
, &nd
);
2304 dentry
= lookup_create(&nd
, 0);
2305 error
= PTR_ERR(dentry
);
2309 error
= vfs_symlink(nd
.path
.dentry
->d_inode
, dentry
, from
, S_IALLUGO
);
2312 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2321 asmlinkage
long sys_symlink(const char __user
*oldname
, const char __user
*newname
)
2323 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
2326 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
)
2328 struct inode
*inode
= old_dentry
->d_inode
;
2334 error
= may_create(dir
, new_dentry
, NULL
);
2338 if (dir
->i_sb
!= inode
->i_sb
)
2342 * A link to an append-only or immutable file cannot be created.
2344 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
2346 if (!dir
->i_op
|| !dir
->i_op
->link
)
2348 if (S_ISDIR(old_dentry
->d_inode
->i_mode
))
2351 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
2355 mutex_lock(&old_dentry
->d_inode
->i_mutex
);
2357 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
2358 mutex_unlock(&old_dentry
->d_inode
->i_mutex
);
2360 fsnotify_link(dir
, old_dentry
->d_inode
, new_dentry
);
2365 * Hardlinks are often used in delicate situations. We avoid
2366 * security-related surprises by not following symlinks on the
2369 * We don't follow them on the oldname either to be compatible
2370 * with linux 2.0, and to avoid hard-linking to directories
2371 * and other special files. --ADM
2373 asmlinkage
long sys_linkat(int olddfd
, const char __user
*oldname
,
2374 int newdfd
, const char __user
*newname
,
2377 struct dentry
*new_dentry
;
2378 struct nameidata nd
, old_nd
;
2382 if ((flags
& ~AT_SYMLINK_FOLLOW
) != 0)
2385 to
= getname(newname
);
2389 error
= __user_walk_fd(olddfd
, oldname
,
2390 flags
& AT_SYMLINK_FOLLOW
? LOOKUP_FOLLOW
: 0,
2394 error
= do_path_lookup(newdfd
, to
, LOOKUP_PARENT
, &nd
);
2398 if (old_nd
.path
.mnt
!= nd
.path
.mnt
)
2400 new_dentry
= lookup_create(&nd
, 0);
2401 error
= PTR_ERR(new_dentry
);
2402 if (IS_ERR(new_dentry
))
2404 error
= vfs_link(old_nd
.path
.dentry
, nd
.path
.dentry
->d_inode
, new_dentry
);
2407 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2411 path_put(&old_nd
.path
);
2418 asmlinkage
long sys_link(const char __user
*oldname
, const char __user
*newname
)
2420 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
2424 * The worst of all namespace operations - renaming directory. "Perverted"
2425 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2427 * a) we can get into loop creation. Check is done in is_subdir().
2428 * b) race potential - two innocent renames can create a loop together.
2429 * That's where 4.4 screws up. Current fix: serialization on
2430 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2432 * c) we have to lock _three_ objects - parents and victim (if it exists).
2433 * And that - after we got ->i_mutex on parents (until then we don't know
2434 * whether the target exists). Solution: try to be smart with locking
2435 * order for inodes. We rely on the fact that tree topology may change
2436 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2437 * move will be locked. Thus we can rank directories by the tree
2438 * (ancestors first) and rank all non-directories after them.
2439 * That works since everybody except rename does "lock parent, lookup,
2440 * lock child" and rename is under ->s_vfs_rename_mutex.
2441 * HOWEVER, it relies on the assumption that any object with ->lookup()
2442 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2443 * we'd better make sure that there's no link(2) for them.
2444 * d) some filesystems don't support opened-but-unlinked directories,
2445 * either because of layout or because they are not ready to deal with
2446 * all cases correctly. The latter will be fixed (taking this sort of
2447 * stuff into VFS), but the former is not going away. Solution: the same
2448 * trick as in rmdir().
2449 * e) conversion from fhandle to dentry may come in the wrong moment - when
2450 * we are removing the target. Solution: we will have to grab ->i_mutex
2451 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2452 * ->i_mutex on parents, which works but leads to some truely excessive
2455 static int vfs_rename_dir(struct inode
*old_dir
, struct dentry
*old_dentry
,
2456 struct inode
*new_dir
, struct dentry
*new_dentry
)
2459 struct inode
*target
;
2462 * If we are going to change the parent - check write permissions,
2463 * we'll need to flip '..'.
2465 if (new_dir
!= old_dir
) {
2466 error
= permission(old_dentry
->d_inode
, MAY_WRITE
, NULL
);
2471 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2475 target
= new_dentry
->d_inode
;
2477 mutex_lock(&target
->i_mutex
);
2478 dentry_unhash(new_dentry
);
2480 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2483 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2486 target
->i_flags
|= S_DEAD
;
2487 mutex_unlock(&target
->i_mutex
);
2488 if (d_unhashed(new_dentry
))
2489 d_rehash(new_dentry
);
2493 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2494 d_move(old_dentry
,new_dentry
);
2498 static int vfs_rename_other(struct inode
*old_dir
, struct dentry
*old_dentry
,
2499 struct inode
*new_dir
, struct dentry
*new_dentry
)
2501 struct inode
*target
;
2504 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2509 target
= new_dentry
->d_inode
;
2511 mutex_lock(&target
->i_mutex
);
2512 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2515 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2517 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2518 d_move(old_dentry
, new_dentry
);
2521 mutex_unlock(&target
->i_mutex
);
2526 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2527 struct inode
*new_dir
, struct dentry
*new_dentry
)
2530 int is_dir
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
2531 const char *old_name
;
2533 if (old_dentry
->d_inode
== new_dentry
->d_inode
)
2536 error
= may_delete(old_dir
, old_dentry
, is_dir
);
2540 if (!new_dentry
->d_inode
)
2541 error
= may_create(new_dir
, new_dentry
, NULL
);
2543 error
= may_delete(new_dir
, new_dentry
, is_dir
);
2547 if (!old_dir
->i_op
|| !old_dir
->i_op
->rename
)
2550 DQUOT_INIT(old_dir
);
2551 DQUOT_INIT(new_dir
);
2553 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
2556 error
= vfs_rename_dir(old_dir
,old_dentry
,new_dir
,new_dentry
);
2558 error
= vfs_rename_other(old_dir
,old_dentry
,new_dir
,new_dentry
);
2560 const char *new_name
= old_dentry
->d_name
.name
;
2561 fsnotify_move(old_dir
, new_dir
, old_name
, new_name
, is_dir
,
2562 new_dentry
->d_inode
, old_dentry
);
2564 fsnotify_oldname_free(old_name
);
2569 static int do_rename(int olddfd
, const char *oldname
,
2570 int newdfd
, const char *newname
)
2573 struct dentry
* old_dir
, * new_dir
;
2574 struct dentry
* old_dentry
, *new_dentry
;
2575 struct dentry
* trap
;
2576 struct nameidata oldnd
, newnd
;
2578 error
= do_path_lookup(olddfd
, oldname
, LOOKUP_PARENT
, &oldnd
);
2582 error
= do_path_lookup(newdfd
, newname
, LOOKUP_PARENT
, &newnd
);
2587 if (oldnd
.path
.mnt
!= newnd
.path
.mnt
)
2590 old_dir
= oldnd
.path
.dentry
;
2592 if (oldnd
.last_type
!= LAST_NORM
)
2595 new_dir
= newnd
.path
.dentry
;
2596 if (newnd
.last_type
!= LAST_NORM
)
2599 trap
= lock_rename(new_dir
, old_dir
);
2601 old_dentry
= lookup_hash(&oldnd
);
2602 error
= PTR_ERR(old_dentry
);
2603 if (IS_ERR(old_dentry
))
2605 /* source must exist */
2607 if (!old_dentry
->d_inode
)
2609 /* unless the source is a directory trailing slashes give -ENOTDIR */
2610 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
)) {
2612 if (oldnd
.last
.name
[oldnd
.last
.len
])
2614 if (newnd
.last
.name
[newnd
.last
.len
])
2617 /* source should not be ancestor of target */
2619 if (old_dentry
== trap
)
2621 new_dentry
= lookup_hash(&newnd
);
2622 error
= PTR_ERR(new_dentry
);
2623 if (IS_ERR(new_dentry
))
2625 /* target should not be an ancestor of source */
2627 if (new_dentry
== trap
)
2630 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
2631 new_dir
->d_inode
, new_dentry
);
2637 unlock_rename(new_dir
, old_dir
);
2639 path_put(&newnd
.path
);
2641 path_put(&oldnd
.path
);
2646 asmlinkage
long sys_renameat(int olddfd
, const char __user
*oldname
,
2647 int newdfd
, const char __user
*newname
)
2653 from
= getname(oldname
);
2655 return PTR_ERR(from
);
2656 to
= getname(newname
);
2657 error
= PTR_ERR(to
);
2659 error
= do_rename(olddfd
, from
, newdfd
, to
);
2666 asmlinkage
long sys_rename(const char __user
*oldname
, const char __user
*newname
)
2668 return sys_renameat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
);
2671 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
, const char *link
)
2675 len
= PTR_ERR(link
);
2680 if (len
> (unsigned) buflen
)
2682 if (copy_to_user(buffer
, link
, len
))
2689 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2690 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2691 * using) it for any given inode is up to filesystem.
2693 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2695 struct nameidata nd
;
2699 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
2700 if (!IS_ERR(cookie
)) {
2701 int res
= vfs_readlink(dentry
, buffer
, buflen
, nd_get_link(&nd
));
2702 if (dentry
->d_inode
->i_op
->put_link
)
2703 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
2704 cookie
= ERR_PTR(res
);
2706 return PTR_ERR(cookie
);
2709 int vfs_follow_link(struct nameidata
*nd
, const char *link
)
2711 return __vfs_follow_link(nd
, link
);
2714 /* get the link contents into pagecache */
2715 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
2718 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
2719 page
= read_mapping_page(mapping
, 0, NULL
);
2726 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2728 struct page
*page
= NULL
;
2729 char *s
= page_getlink(dentry
, &page
);
2730 int res
= vfs_readlink(dentry
,buffer
,buflen
,s
);
2733 page_cache_release(page
);
2738 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
2740 struct page
*page
= NULL
;
2741 nd_set_link(nd
, page_getlink(dentry
, &page
));
2745 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2747 struct page
*page
= cookie
;
2751 page_cache_release(page
);
2755 int __page_symlink(struct inode
*inode
, const char *symname
, int len
,
2758 struct address_space
*mapping
= inode
->i_mapping
;
2765 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
2766 AOP_FLAG_UNINTERRUPTIBLE
, &page
, &fsdata
);
2770 kaddr
= kmap_atomic(page
, KM_USER0
);
2771 memcpy(kaddr
, symname
, len
-1);
2772 kunmap_atomic(kaddr
, KM_USER0
);
2774 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
2781 mark_inode_dirty(inode
);
2787 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
2789 return __page_symlink(inode
, symname
, len
,
2790 mapping_gfp_mask(inode
->i_mapping
));
2793 const struct inode_operations page_symlink_inode_operations
= {
2794 .readlink
= generic_readlink
,
2795 .follow_link
= page_follow_link_light
,
2796 .put_link
= page_put_link
,
2799 EXPORT_SYMBOL(__user_walk
);
2800 EXPORT_SYMBOL(__user_walk_fd
);
2801 EXPORT_SYMBOL(follow_down
);
2802 EXPORT_SYMBOL(follow_up
);
2803 EXPORT_SYMBOL(get_write_access
); /* binfmt_aout */
2804 EXPORT_SYMBOL(getname
);
2805 EXPORT_SYMBOL(lock_rename
);
2806 EXPORT_SYMBOL(lookup_one_len
);
2807 EXPORT_SYMBOL(page_follow_link_light
);
2808 EXPORT_SYMBOL(page_put_link
);
2809 EXPORT_SYMBOL(page_readlink
);
2810 EXPORT_SYMBOL(__page_symlink
);
2811 EXPORT_SYMBOL(page_symlink
);
2812 EXPORT_SYMBOL(page_symlink_inode_operations
);
2813 EXPORT_SYMBOL(path_lookup
);
2814 EXPORT_SYMBOL(vfs_path_lookup
);
2815 EXPORT_SYMBOL(permission
);
2816 EXPORT_SYMBOL(vfs_permission
);
2817 EXPORT_SYMBOL(file_permission
);
2818 EXPORT_SYMBOL(unlock_rename
);
2819 EXPORT_SYMBOL(vfs_create
);
2820 EXPORT_SYMBOL(vfs_follow_link
);
2821 EXPORT_SYMBOL(vfs_link
);
2822 EXPORT_SYMBOL(vfs_mkdir
);
2823 EXPORT_SYMBOL(vfs_mknod
);
2824 EXPORT_SYMBOL(generic_permission
);
2825 EXPORT_SYMBOL(vfs_readlink
);
2826 EXPORT_SYMBOL(vfs_rename
);
2827 EXPORT_SYMBOL(vfs_rmdir
);
2828 EXPORT_SYMBOL(vfs_symlink
);
2829 EXPORT_SYMBOL(vfs_unlink
);
2830 EXPORT_SYMBOL(dentry_unhash
);
2831 EXPORT_SYMBOL(generic_readlink
);