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/smp_lock.h>
26 #include <linux/personality.h>
27 #include <linux/security.h>
28 #include <linux/syscalls.h>
29 #include <linux/mount.h>
30 #include <linux/audit.h>
31 #include <linux/file.h>
32 #include <asm/namei.h>
33 #include <asm/uaccess.h>
35 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
37 /* [Feb-1997 T. Schoebel-Theuer]
38 * Fundamental changes in the pathname lookup mechanisms (namei)
39 * were necessary because of omirr. The reason is that omirr needs
40 * to know the _real_ pathname, not the user-supplied one, in case
41 * of symlinks (and also when transname replacements occur).
43 * The new code replaces the old recursive symlink resolution with
44 * an iterative one (in case of non-nested symlink chains). It does
45 * this with calls to <fs>_follow_link().
46 * As a side effect, dir_namei(), _namei() and follow_link() are now
47 * replaced with a single function lookup_dentry() that can handle all
48 * the special cases of the former code.
50 * With the new dcache, the pathname is stored at each inode, at least as
51 * long as the refcount of the inode is positive. As a side effect, the
52 * size of the dcache depends on the inode cache and thus is dynamic.
54 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
55 * resolution to correspond with current state of the code.
57 * Note that the symlink resolution is not *completely* iterative.
58 * There is still a significant amount of tail- and mid- recursion in
59 * the algorithm. Also, note that <fs>_readlink() is not used in
60 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
61 * may return different results than <fs>_follow_link(). Many virtual
62 * filesystems (including /proc) exhibit this behavior.
65 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
66 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
67 * and the name already exists in form of a symlink, try to create the new
68 * name indicated by the symlink. The old code always complained that the
69 * name already exists, due to not following the symlink even if its target
70 * is nonexistent. The new semantics affects also mknod() and link() when
71 * the name is a symlink pointing to a non-existant name.
73 * I don't know which semantics is the right one, since I have no access
74 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
75 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
76 * "old" one. Personally, I think the new semantics is much more logical.
77 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
78 * file does succeed in both HP-UX and SunOs, but not in Solaris
79 * and in the old Linux semantics.
82 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
83 * semantics. See the comments in "open_namei" and "do_link" below.
85 * [10-Sep-98 Alan Modra] Another symlink change.
88 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
89 * inside the path - always follow.
90 * in the last component in creation/removal/renaming - never follow.
91 * if LOOKUP_FOLLOW passed - follow.
92 * if the pathname has trailing slashes - follow.
93 * otherwise - don't follow.
94 * (applied in that order).
96 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
97 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
98 * During the 2.4 we need to fix the userland stuff depending on it -
99 * hopefully we will be able to get rid of that wart in 2.5. So far only
100 * XEmacs seems to be relying on it...
103 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
104 * implemented. Let's see if raised priority of ->s_vfs_rename_sem gives
105 * any extra contention...
108 /* In order to reduce some races, while at the same time doing additional
109 * checking and hopefully speeding things up, we copy filenames to the
110 * kernel data space before using them..
112 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
113 * PATH_MAX includes the nul terminator --RR.
115 static inline int do_getname(const char __user
*filename
, char *page
)
118 unsigned long len
= PATH_MAX
;
120 if (!segment_eq(get_fs(), KERNEL_DS
)) {
121 if ((unsigned long) filename
>= TASK_SIZE
)
123 if (TASK_SIZE
- (unsigned long) filename
< PATH_MAX
)
124 len
= TASK_SIZE
- (unsigned long) filename
;
127 retval
= strncpy_from_user(page
, filename
, len
);
131 return -ENAMETOOLONG
;
137 char * getname(const char __user
* filename
)
141 result
= ERR_PTR(-ENOMEM
);
144 int retval
= do_getname(filename
, tmp
);
149 result
= ERR_PTR(retval
);
152 audit_getname(result
);
156 #ifdef CONFIG_AUDITSYSCALL
157 void putname(const char *name
)
159 if (unlikely(current
->audit_context
))
164 EXPORT_SYMBOL(putname
);
169 * generic_permission - check for access rights on a Posix-like filesystem
170 * @inode: inode to check access rights for
171 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
172 * @check_acl: optional callback to check for Posix ACLs
174 * Used to check for read/write/execute permissions on a file.
175 * We use "fsuid" for this, letting us set arbitrary permissions
176 * for filesystem access without changing the "normal" uids which
177 * are used for other things..
179 int generic_permission(struct inode
*inode
, int mask
,
180 int (*check_acl
)(struct inode
*inode
, int mask
))
182 umode_t mode
= inode
->i_mode
;
184 if (current
->fsuid
== inode
->i_uid
)
187 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
) && check_acl
) {
188 int error
= check_acl(inode
, mask
);
189 if (error
== -EACCES
)
190 goto check_capabilities
;
191 else if (error
!= -EAGAIN
)
195 if (in_group_p(inode
->i_gid
))
200 * If the DACs are ok we don't need any capability check.
202 if (((mode
& mask
& (MAY_READ
|MAY_WRITE
|MAY_EXEC
)) == mask
))
207 * Read/write DACs are always overridable.
208 * Executable DACs are overridable if at least one exec bit is set.
210 if (!(mask
& MAY_EXEC
) ||
211 (inode
->i_mode
& S_IXUGO
) || S_ISDIR(inode
->i_mode
))
212 if (capable(CAP_DAC_OVERRIDE
))
216 * Searching includes executable on directories, else just read.
218 if (mask
== MAY_READ
|| (S_ISDIR(inode
->i_mode
) && !(mask
& MAY_WRITE
)))
219 if (capable(CAP_DAC_READ_SEARCH
))
225 int permission(struct inode
*inode
, int mask
, struct nameidata
*nd
)
229 if (mask
& MAY_WRITE
) {
230 umode_t mode
= inode
->i_mode
;
233 * Nobody gets write access to a read-only fs.
235 if (IS_RDONLY(inode
) &&
236 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
240 * Nobody gets write access to an immutable file.
242 if (IS_IMMUTABLE(inode
))
247 /* Ordinary permission routines do not understand MAY_APPEND. */
248 submask
= mask
& ~MAY_APPEND
;
249 if (inode
->i_op
&& inode
->i_op
->permission
)
250 retval
= inode
->i_op
->permission(inode
, submask
, nd
);
252 retval
= generic_permission(inode
, submask
, NULL
);
256 return security_inode_permission(inode
, mask
, nd
);
260 * vfs_permission - check for access rights to a given path
261 * @nd: lookup result that describes the path
262 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
264 * Used to check for read/write/execute permissions on a path.
265 * We use "fsuid" for this, letting us set arbitrary permissions
266 * for filesystem access without changing the "normal" uids which
267 * are used for other things.
269 int vfs_permission(struct nameidata
*nd
, int mask
)
271 return permission(nd
->dentry
->d_inode
, mask
, nd
);
275 * file_permission - check for additional access rights to a given file
276 * @file: file to check access rights for
277 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
279 * Used to check for read/write/execute permissions on an already opened
283 * Do not use this function in new code. All access checks should
284 * be done using vfs_permission().
286 int file_permission(struct file
*file
, int mask
)
288 return permission(file
->f_dentry
->d_inode
, mask
, NULL
);
292 * get_write_access() gets write permission for a file.
293 * put_write_access() releases this write permission.
294 * This is used for regular files.
295 * We cannot support write (and maybe mmap read-write shared) accesses and
296 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
297 * can have the following values:
298 * 0: no writers, no VM_DENYWRITE mappings
299 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
300 * > 0: (i_writecount) users are writing to the file.
302 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
303 * except for the cases where we don't hold i_writecount yet. Then we need to
304 * use {get,deny}_write_access() - these functions check the sign and refuse
305 * to do the change if sign is wrong. Exclusion between them is provided by
306 * the inode->i_lock spinlock.
309 int get_write_access(struct inode
* inode
)
311 spin_lock(&inode
->i_lock
);
312 if (atomic_read(&inode
->i_writecount
) < 0) {
313 spin_unlock(&inode
->i_lock
);
316 atomic_inc(&inode
->i_writecount
);
317 spin_unlock(&inode
->i_lock
);
322 int deny_write_access(struct file
* file
)
324 struct inode
*inode
= file
->f_dentry
->d_inode
;
326 spin_lock(&inode
->i_lock
);
327 if (atomic_read(&inode
->i_writecount
) > 0) {
328 spin_unlock(&inode
->i_lock
);
331 atomic_dec(&inode
->i_writecount
);
332 spin_unlock(&inode
->i_lock
);
337 void path_release(struct nameidata
*nd
)
344 * umount() mustn't call path_release()/mntput() as that would clear
347 void path_release_on_umount(struct nameidata
*nd
)
350 mntput_no_expire(nd
->mnt
);
354 * release_open_intent - free up open intent resources
355 * @nd: pointer to nameidata
357 void release_open_intent(struct nameidata
*nd
)
359 if (nd
->intent
.open
.file
->f_dentry
== NULL
)
360 put_filp(nd
->intent
.open
.file
);
362 fput(nd
->intent
.open
.file
);
366 * Internal lookup() using the new generic dcache.
369 static struct dentry
* cached_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
371 struct dentry
* dentry
= __d_lookup(parent
, name
);
373 /* lockess __d_lookup may fail due to concurrent d_move()
374 * in some unrelated directory, so try with d_lookup
377 dentry
= d_lookup(parent
, name
);
379 if (dentry
&& dentry
->d_op
&& dentry
->d_op
->d_revalidate
) {
380 if (!dentry
->d_op
->d_revalidate(dentry
, nd
) && !d_invalidate(dentry
)) {
389 * Short-cut version of permission(), for calling by
390 * path_walk(), when dcache lock is held. Combines parts
391 * of permission() and generic_permission(), and tests ONLY for
392 * MAY_EXEC permission.
394 * If appropriate, check DAC only. If not appropriate, or
395 * short-cut DAC fails, then call permission() to do more
396 * complete permission check.
398 static inline int exec_permission_lite(struct inode
*inode
,
399 struct nameidata
*nd
)
401 umode_t mode
= inode
->i_mode
;
403 if (inode
->i_op
&& inode
->i_op
->permission
)
406 if (current
->fsuid
== inode
->i_uid
)
408 else if (in_group_p(inode
->i_gid
))
414 if ((inode
->i_mode
& S_IXUGO
) && capable(CAP_DAC_OVERRIDE
))
417 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_OVERRIDE
))
420 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_READ_SEARCH
))
425 return security_inode_permission(inode
, MAY_EXEC
, nd
);
429 * This is called when everything else fails, and we actually have
430 * to go to the low-level filesystem to find out what we should do..
432 * We get the directory semaphore, and after getting that we also
433 * make sure that nobody added the entry to the dcache in the meantime..
436 static struct dentry
* real_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
438 struct dentry
* result
;
439 struct inode
*dir
= parent
->d_inode
;
443 * First re-do the cached lookup just in case it was created
444 * while we waited for the directory semaphore..
446 * FIXME! This could use version numbering or similar to
447 * avoid unnecessary cache lookups.
449 * The "dcache_lock" is purely to protect the RCU list walker
450 * from concurrent renames at this point (we mustn't get false
451 * negatives from the RCU list walk here, unlike the optimistic
454 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
456 result
= d_lookup(parent
, name
);
458 struct dentry
* dentry
= d_alloc(parent
, name
);
459 result
= ERR_PTR(-ENOMEM
);
461 result
= dir
->i_op
->lookup(dir
, dentry
, nd
);
472 * Uhhuh! Nasty case: the cache was re-populated while
473 * we waited on the semaphore. Need to revalidate.
476 if (result
->d_op
&& result
->d_op
->d_revalidate
) {
477 if (!result
->d_op
->d_revalidate(result
, nd
) && !d_invalidate(result
)) {
479 result
= ERR_PTR(-ENOENT
);
485 static int __emul_lookup_dentry(const char *, struct nameidata
*);
489 walk_init_root(const char *name
, struct nameidata
*nd
)
491 read_lock(¤t
->fs
->lock
);
492 if (current
->fs
->altroot
&& !(nd
->flags
& LOOKUP_NOALT
)) {
493 nd
->mnt
= mntget(current
->fs
->altrootmnt
);
494 nd
->dentry
= dget(current
->fs
->altroot
);
495 read_unlock(¤t
->fs
->lock
);
496 if (__emul_lookup_dentry(name
,nd
))
498 read_lock(¤t
->fs
->lock
);
500 nd
->mnt
= mntget(current
->fs
->rootmnt
);
501 nd
->dentry
= dget(current
->fs
->root
);
502 read_unlock(¤t
->fs
->lock
);
506 static inline int __vfs_follow_link(struct nameidata
*nd
, const char *link
)
515 if (!walk_init_root(link
, nd
))
516 /* weird __emul_prefix() stuff did it */
519 res
= link_path_walk(link
, nd
);
521 if (nd
->depth
|| res
|| nd
->last_type
!=LAST_NORM
)
524 * If it is an iterative symlinks resolution in open_namei() we
525 * have to copy the last component. And all that crap because of
526 * bloody create() on broken symlinks. Furrfu...
529 if (unlikely(!name
)) {
533 strcpy(name
, nd
->last
.name
);
534 nd
->last
.name
= name
;
538 return PTR_ERR(link
);
542 struct vfsmount
*mnt
;
543 struct dentry
*dentry
;
546 static inline int __do_follow_link(struct path
*path
, struct nameidata
*nd
)
550 struct dentry
*dentry
= path
->dentry
;
552 touch_atime(path
->mnt
, dentry
);
553 nd_set_link(nd
, NULL
);
555 if (path
->mnt
== nd
->mnt
)
557 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
558 error
= PTR_ERR(cookie
);
559 if (!IS_ERR(cookie
)) {
560 char *s
= nd_get_link(nd
);
563 error
= __vfs_follow_link(nd
, s
);
564 if (dentry
->d_inode
->i_op
->put_link
)
565 dentry
->d_inode
->i_op
->put_link(dentry
, nd
, cookie
);
573 static inline void dput_path(struct path
*path
, struct nameidata
*nd
)
576 if (path
->mnt
!= nd
->mnt
)
580 static inline void path_to_nameidata(struct path
*path
, struct nameidata
*nd
)
583 if (nd
->mnt
!= path
->mnt
)
586 nd
->dentry
= path
->dentry
;
590 * This limits recursive symlink follows to 8, while
591 * limiting consecutive symlinks to 40.
593 * Without that kind of total limit, nasty chains of consecutive
594 * symlinks can cause almost arbitrarily long lookups.
596 static inline int do_follow_link(struct path
*path
, struct nameidata
*nd
)
599 if (current
->link_count
>= MAX_NESTED_LINKS
)
601 if (current
->total_link_count
>= 40)
603 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
605 err
= security_inode_follow_link(path
->dentry
, nd
);
608 current
->link_count
++;
609 current
->total_link_count
++;
611 err
= __do_follow_link(path
, nd
);
612 current
->link_count
--;
621 int follow_up(struct vfsmount
**mnt
, struct dentry
**dentry
)
623 struct vfsmount
*parent
;
624 struct dentry
*mountpoint
;
625 spin_lock(&vfsmount_lock
);
626 parent
=(*mnt
)->mnt_parent
;
627 if (parent
== *mnt
) {
628 spin_unlock(&vfsmount_lock
);
632 mountpoint
=dget((*mnt
)->mnt_mountpoint
);
633 spin_unlock(&vfsmount_lock
);
635 *dentry
= mountpoint
;
641 /* no need for dcache_lock, as serialization is taken care in
644 static int __follow_mount(struct path
*path
)
647 while (d_mountpoint(path
->dentry
)) {
648 struct vfsmount
*mounted
= lookup_mnt(path
->mnt
, path
->dentry
);
655 path
->dentry
= dget(mounted
->mnt_root
);
661 static void follow_mount(struct vfsmount
**mnt
, struct dentry
**dentry
)
663 while (d_mountpoint(*dentry
)) {
664 struct vfsmount
*mounted
= lookup_mnt(*mnt
, *dentry
);
670 *dentry
= dget(mounted
->mnt_root
);
674 /* no need for dcache_lock, as serialization is taken care in
677 int follow_down(struct vfsmount
**mnt
, struct dentry
**dentry
)
679 struct vfsmount
*mounted
;
681 mounted
= lookup_mnt(*mnt
, *dentry
);
686 *dentry
= dget(mounted
->mnt_root
);
692 static inline void follow_dotdot(struct nameidata
*nd
)
695 struct vfsmount
*parent
;
696 struct dentry
*old
= nd
->dentry
;
698 read_lock(¤t
->fs
->lock
);
699 if (nd
->dentry
== current
->fs
->root
&&
700 nd
->mnt
== current
->fs
->rootmnt
) {
701 read_unlock(¤t
->fs
->lock
);
704 read_unlock(¤t
->fs
->lock
);
705 spin_lock(&dcache_lock
);
706 if (nd
->dentry
!= nd
->mnt
->mnt_root
) {
707 nd
->dentry
= dget(nd
->dentry
->d_parent
);
708 spin_unlock(&dcache_lock
);
712 spin_unlock(&dcache_lock
);
713 spin_lock(&vfsmount_lock
);
714 parent
= nd
->mnt
->mnt_parent
;
715 if (parent
== nd
->mnt
) {
716 spin_unlock(&vfsmount_lock
);
720 nd
->dentry
= dget(nd
->mnt
->mnt_mountpoint
);
721 spin_unlock(&vfsmount_lock
);
726 follow_mount(&nd
->mnt
, &nd
->dentry
);
730 * It's more convoluted than I'd like it to be, but... it's still fairly
731 * small and for now I'd prefer to have fast path as straight as possible.
732 * It _is_ time-critical.
734 static int do_lookup(struct nameidata
*nd
, struct qstr
*name
,
737 struct vfsmount
*mnt
= nd
->mnt
;
738 struct dentry
*dentry
= __d_lookup(nd
->dentry
, name
);
742 if (dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
743 goto need_revalidate
;
746 path
->dentry
= dentry
;
747 __follow_mount(path
);
751 dentry
= real_lookup(nd
->dentry
, name
, nd
);
757 if (dentry
->d_op
->d_revalidate(dentry
, nd
))
759 if (d_invalidate(dentry
))
765 return PTR_ERR(dentry
);
770 * This is the basic name resolution function, turning a pathname into
771 * the final dentry. We expect 'base' to be positive and a directory.
773 * Returns 0 and nd will have valid dentry and mnt on success.
774 * Returns error and drops reference to input namei data on failure.
776 static fastcall
int __link_path_walk(const char * name
, struct nameidata
*nd
)
781 unsigned int lookup_flags
= nd
->flags
;
788 inode
= nd
->dentry
->d_inode
;
790 lookup_flags
= LOOKUP_FOLLOW
;
792 /* At this point we know we have a real path component. */
798 nd
->flags
|= LOOKUP_CONTINUE
;
799 err
= exec_permission_lite(inode
, nd
);
801 err
= vfs_permission(nd
, MAY_EXEC
);
806 c
= *(const unsigned char *)name
;
808 hash
= init_name_hash();
811 hash
= partial_name_hash(c
, hash
);
812 c
= *(const unsigned char *)name
;
813 } while (c
&& (c
!= '/'));
814 this.len
= name
- (const char *) this.name
;
815 this.hash
= end_name_hash(hash
);
817 /* remove trailing slashes? */
820 while (*++name
== '/');
822 goto last_with_slashes
;
825 * "." and ".." are special - ".." especially so because it has
826 * to be able to know about the current root directory and
827 * parent relationships.
829 if (this.name
[0] == '.') switch (this.len
) {
833 if (this.name
[1] != '.')
836 inode
= nd
->dentry
->d_inode
;
842 * See if the low-level filesystem might want
843 * to use its own hash..
845 if (nd
->dentry
->d_op
&& nd
->dentry
->d_op
->d_hash
) {
846 err
= nd
->dentry
->d_op
->d_hash(nd
->dentry
, &this);
850 /* This does the actual lookups.. */
851 err
= do_lookup(nd
, &this, &next
);
856 inode
= next
.dentry
->d_inode
;
863 if (inode
->i_op
->follow_link
) {
864 err
= do_follow_link(&next
, nd
);
868 inode
= nd
->dentry
->d_inode
;
875 path_to_nameidata(&next
, nd
);
877 if (!inode
->i_op
->lookup
)
880 /* here ends the main loop */
883 lookup_flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
885 nd
->flags
&= ~LOOKUP_CONTINUE
;
886 if (lookup_flags
& LOOKUP_PARENT
)
888 if (this.name
[0] == '.') switch (this.len
) {
892 if (this.name
[1] != '.')
895 inode
= nd
->dentry
->d_inode
;
900 if (nd
->dentry
->d_op
&& nd
->dentry
->d_op
->d_hash
) {
901 err
= nd
->dentry
->d_op
->d_hash(nd
->dentry
, &this);
905 err
= do_lookup(nd
, &this, &next
);
908 inode
= next
.dentry
->d_inode
;
909 if ((lookup_flags
& LOOKUP_FOLLOW
)
910 && inode
&& inode
->i_op
&& inode
->i_op
->follow_link
) {
911 err
= do_follow_link(&next
, nd
);
914 inode
= nd
->dentry
->d_inode
;
916 path_to_nameidata(&next
, nd
);
920 if (lookup_flags
& LOOKUP_DIRECTORY
) {
922 if (!inode
->i_op
|| !inode
->i_op
->lookup
)
928 nd
->last_type
= LAST_NORM
;
929 if (this.name
[0] != '.')
932 nd
->last_type
= LAST_DOT
;
933 else if (this.len
== 2 && this.name
[1] == '.')
934 nd
->last_type
= LAST_DOTDOT
;
939 * We bypassed the ordinary revalidation routines.
940 * We may need to check the cached dentry for staleness.
942 if (nd
->dentry
&& nd
->dentry
->d_sb
&&
943 (nd
->dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
)) {
945 /* Note: we do not d_invalidate() */
946 if (!nd
->dentry
->d_op
->d_revalidate(nd
->dentry
, nd
))
952 dput_path(&next
, nd
);
961 * Wrapper to retry pathname resolution whenever the underlying
962 * file system returns an ESTALE.
964 * Retry the whole path once, forcing real lookup requests
965 * instead of relying on the dcache.
967 int fastcall
link_path_walk(const char *name
, struct nameidata
*nd
)
969 struct nameidata save
= *nd
;
972 /* make sure the stuff we saved doesn't go away */
976 result
= __link_path_walk(name
, nd
);
977 if (result
== -ESTALE
) {
981 nd
->flags
|= LOOKUP_REVAL
;
982 result
= __link_path_walk(name
, nd
);
991 int fastcall
path_walk(const char * name
, struct nameidata
*nd
)
993 current
->total_link_count
= 0;
994 return link_path_walk(name
, nd
);
998 * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
999 * everything is done. Returns 0 and drops input nd, if lookup failed;
1001 static int __emul_lookup_dentry(const char *name
, struct nameidata
*nd
)
1003 if (path_walk(name
, nd
))
1004 return 0; /* something went wrong... */
1006 if (!nd
->dentry
->d_inode
|| S_ISDIR(nd
->dentry
->d_inode
->i_mode
)) {
1007 struct dentry
*old_dentry
= nd
->dentry
;
1008 struct vfsmount
*old_mnt
= nd
->mnt
;
1009 struct qstr last
= nd
->last
;
1010 int last_type
= nd
->last_type
;
1012 * NAME was not found in alternate root or it's a directory. Try to find
1013 * it in the normal root:
1015 nd
->last_type
= LAST_ROOT
;
1016 read_lock(¤t
->fs
->lock
);
1017 nd
->mnt
= mntget(current
->fs
->rootmnt
);
1018 nd
->dentry
= dget(current
->fs
->root
);
1019 read_unlock(¤t
->fs
->lock
);
1020 if (path_walk(name
, nd
) == 0) {
1021 if (nd
->dentry
->d_inode
) {
1028 nd
->dentry
= old_dentry
;
1031 nd
->last_type
= last_type
;
1036 void set_fs_altroot(void)
1038 char *emul
= __emul_prefix();
1039 struct nameidata nd
;
1040 struct vfsmount
*mnt
= NULL
, *oldmnt
;
1041 struct dentry
*dentry
= NULL
, *olddentry
;
1046 err
= path_lookup(emul
, LOOKUP_FOLLOW
|LOOKUP_DIRECTORY
|LOOKUP_NOALT
, &nd
);
1052 write_lock(¤t
->fs
->lock
);
1053 oldmnt
= current
->fs
->altrootmnt
;
1054 olddentry
= current
->fs
->altroot
;
1055 current
->fs
->altrootmnt
= mnt
;
1056 current
->fs
->altroot
= dentry
;
1057 write_unlock(¤t
->fs
->lock
);
1064 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1065 int fastcall
path_lookup(const char *name
, unsigned int flags
, struct nameidata
*nd
)
1069 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1073 read_lock(¤t
->fs
->lock
);
1075 if (current
->fs
->altroot
&& !(nd
->flags
& LOOKUP_NOALT
)) {
1076 nd
->mnt
= mntget(current
->fs
->altrootmnt
);
1077 nd
->dentry
= dget(current
->fs
->altroot
);
1078 read_unlock(¤t
->fs
->lock
);
1079 if (__emul_lookup_dentry(name
,nd
))
1080 goto out
; /* found in altroot */
1081 read_lock(¤t
->fs
->lock
);
1083 nd
->mnt
= mntget(current
->fs
->rootmnt
);
1084 nd
->dentry
= dget(current
->fs
->root
);
1086 nd
->mnt
= mntget(current
->fs
->pwdmnt
);
1087 nd
->dentry
= dget(current
->fs
->pwd
);
1089 read_unlock(¤t
->fs
->lock
);
1090 current
->total_link_count
= 0;
1091 retval
= link_path_walk(name
, nd
);
1093 if (unlikely(current
->audit_context
1094 && nd
&& nd
->dentry
&& nd
->dentry
->d_inode
))
1095 audit_inode(name
, nd
->dentry
->d_inode
, flags
);
1099 static int __path_lookup_intent_open(const char *name
, unsigned int lookup_flags
,
1100 struct nameidata
*nd
, int open_flags
, int create_mode
)
1102 struct file
*filp
= get_empty_filp();
1107 nd
->intent
.open
.file
= filp
;
1108 nd
->intent
.open
.flags
= open_flags
;
1109 nd
->intent
.open
.create_mode
= create_mode
;
1110 err
= path_lookup(name
, lookup_flags
|LOOKUP_OPEN
, nd
);
1111 if (IS_ERR(nd
->intent
.open
.file
)) {
1113 err
= PTR_ERR(nd
->intent
.open
.file
);
1116 } else if (err
!= 0)
1117 release_open_intent(nd
);
1122 * path_lookup_open - lookup a file path with open intent
1123 * @name: pointer to file name
1124 * @lookup_flags: lookup intent flags
1125 * @nd: pointer to nameidata
1126 * @open_flags: open intent flags
1128 int path_lookup_open(const char *name
, unsigned int lookup_flags
,
1129 struct nameidata
*nd
, int open_flags
)
1131 return __path_lookup_intent_open(name
, lookup_flags
, nd
,
1136 * path_lookup_create - lookup a file path with open + create intent
1137 * @name: pointer to file name
1138 * @lookup_flags: lookup intent flags
1139 * @nd: pointer to nameidata
1140 * @open_flags: open intent flags
1141 * @create_mode: create intent flags
1143 int path_lookup_create(const char *name
, unsigned int lookup_flags
,
1144 struct nameidata
*nd
, int open_flags
, int create_mode
)
1146 return __path_lookup_intent_open(name
, lookup_flags
|LOOKUP_CREATE
, nd
,
1147 open_flags
, create_mode
);
1150 int __user_path_lookup_open(const char __user
*name
, unsigned int lookup_flags
,
1151 struct nameidata
*nd
, int open_flags
)
1153 char *tmp
= getname(name
);
1154 int err
= PTR_ERR(tmp
);
1157 err
= __path_lookup_intent_open(tmp
, lookup_flags
, nd
, open_flags
, 0);
1164 * Restricted form of lookup. Doesn't follow links, single-component only,
1165 * needs parent already locked. Doesn't follow mounts.
1168 static struct dentry
* __lookup_hash(struct qstr
*name
, struct dentry
* base
, struct nameidata
*nd
)
1170 struct dentry
* dentry
;
1171 struct inode
*inode
;
1174 inode
= base
->d_inode
;
1175 err
= permission(inode
, MAY_EXEC
, nd
);
1176 dentry
= ERR_PTR(err
);
1181 * See if the low-level filesystem might want
1182 * to use its own hash..
1184 if (base
->d_op
&& base
->d_op
->d_hash
) {
1185 err
= base
->d_op
->d_hash(base
, name
);
1186 dentry
= ERR_PTR(err
);
1191 dentry
= cached_lookup(base
, name
, nd
);
1193 struct dentry
*new = d_alloc(base
, name
);
1194 dentry
= ERR_PTR(-ENOMEM
);
1197 dentry
= inode
->i_op
->lookup(inode
, new, nd
);
1207 struct dentry
* lookup_hash(struct nameidata
*nd
)
1209 return __lookup_hash(&nd
->last
, nd
->dentry
, nd
);
1213 struct dentry
* lookup_one_len(const char * name
, struct dentry
* base
, int len
)
1224 hash
= init_name_hash();
1226 c
= *(const unsigned char *)name
++;
1227 if (c
== '/' || c
== '\0')
1229 hash
= partial_name_hash(c
, hash
);
1231 this.hash
= end_name_hash(hash
);
1233 return __lookup_hash(&this, base
, NULL
);
1235 return ERR_PTR(-EACCES
);
1241 * is used by most simple commands to get the inode of a specified name.
1242 * Open, link etc use their own routines, but this is enough for things
1245 * namei exists in two versions: namei/lnamei. The only difference is
1246 * that namei follows links, while lnamei does not.
1249 int fastcall
__user_walk(const char __user
*name
, unsigned flags
, struct nameidata
*nd
)
1251 char *tmp
= getname(name
);
1252 int err
= PTR_ERR(tmp
);
1255 err
= path_lookup(tmp
, flags
, nd
);
1262 * It's inline, so penalty for filesystems that don't use sticky bit is
1265 static inline int check_sticky(struct inode
*dir
, struct inode
*inode
)
1267 if (!(dir
->i_mode
& S_ISVTX
))
1269 if (inode
->i_uid
== current
->fsuid
)
1271 if (dir
->i_uid
== current
->fsuid
)
1273 return !capable(CAP_FOWNER
);
1277 * Check whether we can remove a link victim from directory dir, check
1278 * whether the type of victim is right.
1279 * 1. We can't do it if dir is read-only (done in permission())
1280 * 2. We should have write and exec permissions on dir
1281 * 3. We can't remove anything from append-only dir
1282 * 4. We can't do anything with immutable dir (done in permission())
1283 * 5. If the sticky bit on dir is set we should either
1284 * a. be owner of dir, or
1285 * b. be owner of victim, or
1286 * c. have CAP_FOWNER capability
1287 * 6. If the victim is append-only or immutable we can't do antyhing with
1288 * links pointing to it.
1289 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1290 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1291 * 9. We can't remove a root or mountpoint.
1292 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1293 * nfs_async_unlink().
1295 static inline int may_delete(struct inode
*dir
,struct dentry
*victim
,int isdir
)
1299 if (!victim
->d_inode
)
1302 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
1304 error
= permission(dir
,MAY_WRITE
| MAY_EXEC
, NULL
);
1309 if (check_sticky(dir
, victim
->d_inode
)||IS_APPEND(victim
->d_inode
)||
1310 IS_IMMUTABLE(victim
->d_inode
))
1313 if (!S_ISDIR(victim
->d_inode
->i_mode
))
1315 if (IS_ROOT(victim
))
1317 } else if (S_ISDIR(victim
->d_inode
->i_mode
))
1319 if (IS_DEADDIR(dir
))
1321 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
1326 /* Check whether we can create an object with dentry child in directory
1328 * 1. We can't do it if child already exists (open has special treatment for
1329 * this case, but since we are inlined it's OK)
1330 * 2. We can't do it if dir is read-only (done in permission())
1331 * 3. We should have write and exec permissions on dir
1332 * 4. We can't do it if dir is immutable (done in permission())
1334 static inline int may_create(struct inode
*dir
, struct dentry
*child
,
1335 struct nameidata
*nd
)
1339 if (IS_DEADDIR(dir
))
1341 return permission(dir
,MAY_WRITE
| MAY_EXEC
, nd
);
1345 * O_DIRECTORY translates into forcing a directory lookup.
1347 static inline int lookup_flags(unsigned int f
)
1349 unsigned long retval
= LOOKUP_FOLLOW
;
1352 retval
&= ~LOOKUP_FOLLOW
;
1354 if (f
& O_DIRECTORY
)
1355 retval
|= LOOKUP_DIRECTORY
;
1361 * p1 and p2 should be directories on the same fs.
1363 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
1368 down(&p1
->d_inode
->i_sem
);
1372 down(&p1
->d_inode
->i_sb
->s_vfs_rename_sem
);
1374 for (p
= p1
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1375 if (p
->d_parent
== p2
) {
1376 down(&p2
->d_inode
->i_sem
);
1377 down(&p1
->d_inode
->i_sem
);
1382 for (p
= p2
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1383 if (p
->d_parent
== p1
) {
1384 down(&p1
->d_inode
->i_sem
);
1385 down(&p2
->d_inode
->i_sem
);
1390 down(&p1
->d_inode
->i_sem
);
1391 down(&p2
->d_inode
->i_sem
);
1395 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
1397 up(&p1
->d_inode
->i_sem
);
1399 up(&p2
->d_inode
->i_sem
);
1400 up(&p1
->d_inode
->i_sb
->s_vfs_rename_sem
);
1404 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1405 struct nameidata
*nd
)
1407 int error
= may_create(dir
, dentry
, nd
);
1412 if (!dir
->i_op
|| !dir
->i_op
->create
)
1413 return -EACCES
; /* shouldn't it be ENOSYS? */
1416 error
= security_inode_create(dir
, dentry
, mode
);
1420 error
= dir
->i_op
->create(dir
, dentry
, mode
, nd
);
1422 fsnotify_create(dir
, dentry
->d_name
.name
);
1426 int may_open(struct nameidata
*nd
, int acc_mode
, int flag
)
1428 struct dentry
*dentry
= nd
->dentry
;
1429 struct inode
*inode
= dentry
->d_inode
;
1435 if (S_ISLNK(inode
->i_mode
))
1438 if (S_ISDIR(inode
->i_mode
) && (flag
& FMODE_WRITE
))
1441 error
= vfs_permission(nd
, acc_mode
);
1446 * FIFO's, sockets and device files are special: they don't
1447 * actually live on the filesystem itself, and as such you
1448 * can write to them even if the filesystem is read-only.
1450 if (S_ISFIFO(inode
->i_mode
) || S_ISSOCK(inode
->i_mode
)) {
1452 } else if (S_ISBLK(inode
->i_mode
) || S_ISCHR(inode
->i_mode
)) {
1453 if (nd
->mnt
->mnt_flags
& MNT_NODEV
)
1457 } else if (IS_RDONLY(inode
) && (flag
& FMODE_WRITE
))
1460 * An append-only file must be opened in append mode for writing.
1462 if (IS_APPEND(inode
)) {
1463 if ((flag
& FMODE_WRITE
) && !(flag
& O_APPEND
))
1469 /* O_NOATIME can only be set by the owner or superuser */
1470 if (flag
& O_NOATIME
)
1471 if (current
->fsuid
!= inode
->i_uid
&& !capable(CAP_FOWNER
))
1475 * Ensure there are no outstanding leases on the file.
1477 error
= break_lease(inode
, flag
);
1481 if (flag
& O_TRUNC
) {
1482 error
= get_write_access(inode
);
1487 * Refuse to truncate files with mandatory locks held on them.
1489 error
= locks_verify_locked(inode
);
1493 error
= do_truncate(dentry
, 0, NULL
);
1495 put_write_access(inode
);
1499 if (flag
& FMODE_WRITE
)
1508 * namei for open - this is in fact almost the whole open-routine.
1510 * Note that the low bits of "flag" aren't the same as in the open
1511 * system call - they are 00 - no permissions needed
1512 * 01 - read permission needed
1513 * 10 - write permission needed
1514 * 11 - read/write permissions needed
1515 * which is a lot more logical, and also allows the "no perm" needed
1516 * for symlinks (where the permissions are checked later).
1519 int open_namei(const char * pathname
, int flag
, int mode
, struct nameidata
*nd
)
1521 int acc_mode
, error
;
1526 acc_mode
= ACC_MODE(flag
);
1528 /* O_TRUNC implies we need access checks for write permissions */
1530 acc_mode
|= MAY_WRITE
;
1532 /* Allow the LSM permission hook to distinguish append
1533 access from general write access. */
1534 if (flag
& O_APPEND
)
1535 acc_mode
|= MAY_APPEND
;
1538 * The simplest case - just a plain lookup.
1540 if (!(flag
& O_CREAT
)) {
1541 error
= path_lookup_open(pathname
, lookup_flags(flag
), nd
, flag
);
1548 * Create - we need to know the parent.
1550 error
= path_lookup_create(pathname
, LOOKUP_PARENT
, nd
, flag
, mode
);
1555 * We have the parent and last component. First of all, check
1556 * that we are not asked to creat(2) an obvious directory - that
1560 if (nd
->last_type
!= LAST_NORM
|| nd
->last
.name
[nd
->last
.len
])
1564 nd
->flags
&= ~LOOKUP_PARENT
;
1565 down(&dir
->d_inode
->i_sem
);
1566 path
.dentry
= lookup_hash(nd
);
1570 error
= PTR_ERR(path
.dentry
);
1571 if (IS_ERR(path
.dentry
)) {
1572 up(&dir
->d_inode
->i_sem
);
1576 /* Negative dentry, just create the file */
1577 if (!path
.dentry
->d_inode
) {
1578 if (!IS_POSIXACL(dir
->d_inode
))
1579 mode
&= ~current
->fs
->umask
;
1580 error
= vfs_create(dir
->d_inode
, path
.dentry
, mode
, nd
);
1581 up(&dir
->d_inode
->i_sem
);
1583 nd
->dentry
= path
.dentry
;
1586 /* Don't check for write permission, don't truncate */
1593 * It already exists.
1595 up(&dir
->d_inode
->i_sem
);
1601 if (__follow_mount(&path
)) {
1603 if (flag
& O_NOFOLLOW
)
1607 if (!path
.dentry
->d_inode
)
1609 if (path
.dentry
->d_inode
->i_op
&& path
.dentry
->d_inode
->i_op
->follow_link
)
1612 path_to_nameidata(&path
, nd
);
1614 if (path
.dentry
->d_inode
&& S_ISDIR(path
.dentry
->d_inode
->i_mode
))
1617 error
= may_open(nd
, acc_mode
, flag
);
1623 dput_path(&path
, nd
);
1625 if (!IS_ERR(nd
->intent
.open
.file
))
1626 release_open_intent(nd
);
1632 if (flag
& O_NOFOLLOW
)
1635 * This is subtle. Instead of calling do_follow_link() we do the
1636 * thing by hands. The reason is that this way we have zero link_count
1637 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1638 * After that we have the parent and last component, i.e.
1639 * we are in the same situation as after the first path_walk().
1640 * Well, almost - if the last component is normal we get its copy
1641 * stored in nd->last.name and we will have to putname() it when we
1642 * are done. Procfs-like symlinks just set LAST_BIND.
1644 nd
->flags
|= LOOKUP_PARENT
;
1645 error
= security_inode_follow_link(path
.dentry
, nd
);
1648 error
= __do_follow_link(&path
, nd
);
1651 nd
->flags
&= ~LOOKUP_PARENT
;
1652 if (nd
->last_type
== LAST_BIND
)
1655 if (nd
->last_type
!= LAST_NORM
)
1657 if (nd
->last
.name
[nd
->last
.len
]) {
1658 __putname(nd
->last
.name
);
1663 __putname(nd
->last
.name
);
1667 down(&dir
->d_inode
->i_sem
);
1668 path
.dentry
= lookup_hash(nd
);
1670 __putname(nd
->last
.name
);
1675 * lookup_create - lookup a dentry, creating it if it doesn't exist
1676 * @nd: nameidata info
1677 * @is_dir: directory flag
1679 * Simple function to lookup and return a dentry and create it
1680 * if it doesn't exist. Is SMP-safe.
1682 * Returns with nd->dentry->d_inode->i_sem locked.
1684 struct dentry
*lookup_create(struct nameidata
*nd
, int is_dir
)
1686 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
1688 down(&nd
->dentry
->d_inode
->i_sem
);
1690 * Yucky last component or no last component at all?
1691 * (foo/., foo/.., /////)
1693 if (nd
->last_type
!= LAST_NORM
)
1695 nd
->flags
&= ~LOOKUP_PARENT
;
1698 * Do the final lookup.
1700 dentry
= lookup_hash(nd
);
1705 * Special case - lookup gave negative, but... we had foo/bar/
1706 * From the vfs_mknod() POV we just have a negative dentry -
1707 * all is fine. Let's be bastards - you had / on the end, you've
1708 * been asking for (non-existent) directory. -ENOENT for you.
1710 if (!is_dir
&& nd
->last
.name
[nd
->last
.len
] && !dentry
->d_inode
)
1715 dentry
= ERR_PTR(-ENOENT
);
1719 EXPORT_SYMBOL_GPL(lookup_create
);
1721 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1723 int error
= may_create(dir
, dentry
, NULL
);
1728 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
1731 if (!dir
->i_op
|| !dir
->i_op
->mknod
)
1734 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
1739 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
1741 fsnotify_create(dir
, dentry
->d_name
.name
);
1745 asmlinkage
long sys_mknod(const char __user
* filename
, int mode
, unsigned dev
)
1749 struct dentry
* dentry
;
1750 struct nameidata nd
;
1754 tmp
= getname(filename
);
1756 return PTR_ERR(tmp
);
1758 error
= path_lookup(tmp
, LOOKUP_PARENT
, &nd
);
1761 dentry
= lookup_create(&nd
, 0);
1762 error
= PTR_ERR(dentry
);
1764 if (!IS_POSIXACL(nd
.dentry
->d_inode
))
1765 mode
&= ~current
->fs
->umask
;
1766 if (!IS_ERR(dentry
)) {
1767 switch (mode
& S_IFMT
) {
1768 case 0: case S_IFREG
:
1769 error
= vfs_create(nd
.dentry
->d_inode
,dentry
,mode
,&nd
);
1771 case S_IFCHR
: case S_IFBLK
:
1772 error
= vfs_mknod(nd
.dentry
->d_inode
,dentry
,mode
,
1773 new_decode_dev(dev
));
1775 case S_IFIFO
: case S_IFSOCK
:
1776 error
= vfs_mknod(nd
.dentry
->d_inode
,dentry
,mode
,0);
1786 up(&nd
.dentry
->d_inode
->i_sem
);
1794 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
1796 int error
= may_create(dir
, dentry
, NULL
);
1801 if (!dir
->i_op
|| !dir
->i_op
->mkdir
)
1804 mode
&= (S_IRWXUGO
|S_ISVTX
);
1805 error
= security_inode_mkdir(dir
, dentry
, mode
);
1810 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
1812 fsnotify_mkdir(dir
, dentry
->d_name
.name
);
1816 asmlinkage
long sys_mkdir(const char __user
* pathname
, int mode
)
1821 tmp
= getname(pathname
);
1822 error
= PTR_ERR(tmp
);
1824 struct dentry
*dentry
;
1825 struct nameidata nd
;
1827 error
= path_lookup(tmp
, LOOKUP_PARENT
, &nd
);
1830 dentry
= lookup_create(&nd
, 1);
1831 error
= PTR_ERR(dentry
);
1832 if (!IS_ERR(dentry
)) {
1833 if (!IS_POSIXACL(nd
.dentry
->d_inode
))
1834 mode
&= ~current
->fs
->umask
;
1835 error
= vfs_mkdir(nd
.dentry
->d_inode
, dentry
, mode
);
1838 up(&nd
.dentry
->d_inode
->i_sem
);
1848 * We try to drop the dentry early: we should have
1849 * a usage count of 2 if we're the only user of this
1850 * dentry, and if that is true (possibly after pruning
1851 * the dcache), then we drop the dentry now.
1853 * A low-level filesystem can, if it choses, legally
1856 * if (!d_unhashed(dentry))
1859 * if it cannot handle the case of removing a directory
1860 * that is still in use by something else..
1862 void dentry_unhash(struct dentry
*dentry
)
1865 if (atomic_read(&dentry
->d_count
))
1866 shrink_dcache_parent(dentry
);
1867 spin_lock(&dcache_lock
);
1868 spin_lock(&dentry
->d_lock
);
1869 if (atomic_read(&dentry
->d_count
) == 2)
1871 spin_unlock(&dentry
->d_lock
);
1872 spin_unlock(&dcache_lock
);
1875 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
1877 int error
= may_delete(dir
, dentry
, 1);
1882 if (!dir
->i_op
|| !dir
->i_op
->rmdir
)
1887 down(&dentry
->d_inode
->i_sem
);
1888 dentry_unhash(dentry
);
1889 if (d_mountpoint(dentry
))
1892 error
= security_inode_rmdir(dir
, dentry
);
1894 error
= dir
->i_op
->rmdir(dir
, dentry
);
1896 dentry
->d_inode
->i_flags
|= S_DEAD
;
1899 up(&dentry
->d_inode
->i_sem
);
1908 asmlinkage
long sys_rmdir(const char __user
* pathname
)
1912 struct dentry
*dentry
;
1913 struct nameidata nd
;
1915 name
= getname(pathname
);
1917 return PTR_ERR(name
);
1919 error
= path_lookup(name
, LOOKUP_PARENT
, &nd
);
1923 switch(nd
.last_type
) {
1934 down(&nd
.dentry
->d_inode
->i_sem
);
1935 dentry
= lookup_hash(&nd
);
1936 error
= PTR_ERR(dentry
);
1937 if (!IS_ERR(dentry
)) {
1938 error
= vfs_rmdir(nd
.dentry
->d_inode
, dentry
);
1941 up(&nd
.dentry
->d_inode
->i_sem
);
1949 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
)
1951 int error
= may_delete(dir
, dentry
, 0);
1956 if (!dir
->i_op
|| !dir
->i_op
->unlink
)
1961 down(&dentry
->d_inode
->i_sem
);
1962 if (d_mountpoint(dentry
))
1965 error
= security_inode_unlink(dir
, dentry
);
1967 error
= dir
->i_op
->unlink(dir
, dentry
);
1969 up(&dentry
->d_inode
->i_sem
);
1971 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
1972 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
1980 * Make sure that the actual truncation of the file will occur outside its
1981 * directory's i_sem. Truncate can take a long time if there is a lot of
1982 * writeout happening, and we don't want to prevent access to the directory
1983 * while waiting on the I/O.
1985 asmlinkage
long sys_unlink(const char __user
* pathname
)
1989 struct dentry
*dentry
;
1990 struct nameidata nd
;
1991 struct inode
*inode
= NULL
;
1993 name
= getname(pathname
);
1995 return PTR_ERR(name
);
1997 error
= path_lookup(name
, LOOKUP_PARENT
, &nd
);
2001 if (nd
.last_type
!= LAST_NORM
)
2003 down(&nd
.dentry
->d_inode
->i_sem
);
2004 dentry
= lookup_hash(&nd
);
2005 error
= PTR_ERR(dentry
);
2006 if (!IS_ERR(dentry
)) {
2007 /* Why not before? Because we want correct error value */
2008 if (nd
.last
.name
[nd
.last
.len
])
2010 inode
= dentry
->d_inode
;
2012 atomic_inc(&inode
->i_count
);
2013 error
= vfs_unlink(nd
.dentry
->d_inode
, dentry
);
2017 up(&nd
.dentry
->d_inode
->i_sem
);
2019 iput(inode
); /* truncate the inode here */
2027 error
= !dentry
->d_inode
? -ENOENT
:
2028 S_ISDIR(dentry
->d_inode
->i_mode
) ? -EISDIR
: -ENOTDIR
;
2032 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
, int mode
)
2034 int error
= may_create(dir
, dentry
, NULL
);
2039 if (!dir
->i_op
|| !dir
->i_op
->symlink
)
2042 error
= security_inode_symlink(dir
, dentry
, oldname
);
2047 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
2049 fsnotify_create(dir
, dentry
->d_name
.name
);
2053 asmlinkage
long sys_symlink(const char __user
* oldname
, const char __user
* newname
)
2059 from
= getname(oldname
);
2061 return PTR_ERR(from
);
2062 to
= getname(newname
);
2063 error
= PTR_ERR(to
);
2065 struct dentry
*dentry
;
2066 struct nameidata nd
;
2068 error
= path_lookup(to
, LOOKUP_PARENT
, &nd
);
2071 dentry
= lookup_create(&nd
, 0);
2072 error
= PTR_ERR(dentry
);
2073 if (!IS_ERR(dentry
)) {
2074 error
= vfs_symlink(nd
.dentry
->d_inode
, dentry
, from
, S_IALLUGO
);
2077 up(&nd
.dentry
->d_inode
->i_sem
);
2086 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
)
2088 struct inode
*inode
= old_dentry
->d_inode
;
2094 error
= may_create(dir
, new_dentry
, NULL
);
2098 if (dir
->i_sb
!= inode
->i_sb
)
2102 * A link to an append-only or immutable file cannot be created.
2104 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
2106 if (!dir
->i_op
|| !dir
->i_op
->link
)
2108 if (S_ISDIR(old_dentry
->d_inode
->i_mode
))
2111 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
2115 down(&old_dentry
->d_inode
->i_sem
);
2117 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
2118 up(&old_dentry
->d_inode
->i_sem
);
2120 fsnotify_create(dir
, new_dentry
->d_name
.name
);
2125 * Hardlinks are often used in delicate situations. We avoid
2126 * security-related surprises by not following symlinks on the
2129 * We don't follow them on the oldname either to be compatible
2130 * with linux 2.0, and to avoid hard-linking to directories
2131 * and other special files. --ADM
2133 asmlinkage
long sys_link(const char __user
* oldname
, const char __user
* newname
)
2135 struct dentry
*new_dentry
;
2136 struct nameidata nd
, old_nd
;
2140 to
= getname(newname
);
2144 error
= __user_walk(oldname
, 0, &old_nd
);
2147 error
= path_lookup(to
, LOOKUP_PARENT
, &nd
);
2151 if (old_nd
.mnt
!= nd
.mnt
)
2153 new_dentry
= lookup_create(&nd
, 0);
2154 error
= PTR_ERR(new_dentry
);
2155 if (!IS_ERR(new_dentry
)) {
2156 error
= vfs_link(old_nd
.dentry
, nd
.dentry
->d_inode
, new_dentry
);
2159 up(&nd
.dentry
->d_inode
->i_sem
);
2163 path_release(&old_nd
);
2171 * The worst of all namespace operations - renaming directory. "Perverted"
2172 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2174 * a) we can get into loop creation. Check is done in is_subdir().
2175 * b) race potential - two innocent renames can create a loop together.
2176 * That's where 4.4 screws up. Current fix: serialization on
2177 * sb->s_vfs_rename_sem. We might be more accurate, but that's another
2179 * c) we have to lock _three_ objects - parents and victim (if it exists).
2180 * And that - after we got ->i_sem on parents (until then we don't know
2181 * whether the target exists). Solution: try to be smart with locking
2182 * order for inodes. We rely on the fact that tree topology may change
2183 * only under ->s_vfs_rename_sem _and_ that parent of the object we
2184 * move will be locked. Thus we can rank directories by the tree
2185 * (ancestors first) and rank all non-directories after them.
2186 * That works since everybody except rename does "lock parent, lookup,
2187 * lock child" and rename is under ->s_vfs_rename_sem.
2188 * HOWEVER, it relies on the assumption that any object with ->lookup()
2189 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2190 * we'd better make sure that there's no link(2) for them.
2191 * d) some filesystems don't support opened-but-unlinked directories,
2192 * either because of layout or because they are not ready to deal with
2193 * all cases correctly. The latter will be fixed (taking this sort of
2194 * stuff into VFS), but the former is not going away. Solution: the same
2195 * trick as in rmdir().
2196 * e) conversion from fhandle to dentry may come in the wrong moment - when
2197 * we are removing the target. Solution: we will have to grab ->i_sem
2198 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2199 * ->i_sem on parents, which works but leads to some truely excessive
2202 static int vfs_rename_dir(struct inode
*old_dir
, struct dentry
*old_dentry
,
2203 struct inode
*new_dir
, struct dentry
*new_dentry
)
2206 struct inode
*target
;
2209 * If we are going to change the parent - check write permissions,
2210 * we'll need to flip '..'.
2212 if (new_dir
!= old_dir
) {
2213 error
= permission(old_dentry
->d_inode
, MAY_WRITE
, NULL
);
2218 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2222 target
= new_dentry
->d_inode
;
2224 down(&target
->i_sem
);
2225 dentry_unhash(new_dentry
);
2227 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2230 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2233 target
->i_flags
|= S_DEAD
;
2235 if (d_unhashed(new_dentry
))
2236 d_rehash(new_dentry
);
2240 d_move(old_dentry
,new_dentry
);
2244 static int vfs_rename_other(struct inode
*old_dir
, struct dentry
*old_dentry
,
2245 struct inode
*new_dir
, struct dentry
*new_dentry
)
2247 struct inode
*target
;
2250 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2255 target
= new_dentry
->d_inode
;
2257 down(&target
->i_sem
);
2258 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2261 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2263 /* The following d_move() should become unconditional */
2264 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_ODD_RENAME
))
2265 d_move(old_dentry
, new_dentry
);
2273 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2274 struct inode
*new_dir
, struct dentry
*new_dentry
)
2277 int is_dir
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
2278 const char *old_name
;
2280 if (old_dentry
->d_inode
== new_dentry
->d_inode
)
2283 error
= may_delete(old_dir
, old_dentry
, is_dir
);
2287 if (!new_dentry
->d_inode
)
2288 error
= may_create(new_dir
, new_dentry
, NULL
);
2290 error
= may_delete(new_dir
, new_dentry
, is_dir
);
2294 if (!old_dir
->i_op
|| !old_dir
->i_op
->rename
)
2297 DQUOT_INIT(old_dir
);
2298 DQUOT_INIT(new_dir
);
2300 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
2303 error
= vfs_rename_dir(old_dir
,old_dentry
,new_dir
,new_dentry
);
2305 error
= vfs_rename_other(old_dir
,old_dentry
,new_dir
,new_dentry
);
2307 const char *new_name
= old_dentry
->d_name
.name
;
2308 fsnotify_move(old_dir
, new_dir
, old_name
, new_name
, is_dir
,
2309 new_dentry
->d_inode
, old_dentry
->d_inode
);
2311 fsnotify_oldname_free(old_name
);
2316 static inline int do_rename(const char * oldname
, const char * newname
)
2319 struct dentry
* old_dir
, * new_dir
;
2320 struct dentry
* old_dentry
, *new_dentry
;
2321 struct dentry
* trap
;
2322 struct nameidata oldnd
, newnd
;
2324 error
= path_lookup(oldname
, LOOKUP_PARENT
, &oldnd
);
2328 error
= path_lookup(newname
, LOOKUP_PARENT
, &newnd
);
2333 if (oldnd
.mnt
!= newnd
.mnt
)
2336 old_dir
= oldnd
.dentry
;
2338 if (oldnd
.last_type
!= LAST_NORM
)
2341 new_dir
= newnd
.dentry
;
2342 if (newnd
.last_type
!= LAST_NORM
)
2345 trap
= lock_rename(new_dir
, old_dir
);
2347 old_dentry
= lookup_hash(&oldnd
);
2348 error
= PTR_ERR(old_dentry
);
2349 if (IS_ERR(old_dentry
))
2351 /* source must exist */
2353 if (!old_dentry
->d_inode
)
2355 /* unless the source is a directory trailing slashes give -ENOTDIR */
2356 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
)) {
2358 if (oldnd
.last
.name
[oldnd
.last
.len
])
2360 if (newnd
.last
.name
[newnd
.last
.len
])
2363 /* source should not be ancestor of target */
2365 if (old_dentry
== trap
)
2367 new_dentry
= lookup_hash(&newnd
);
2368 error
= PTR_ERR(new_dentry
);
2369 if (IS_ERR(new_dentry
))
2371 /* target should not be an ancestor of source */
2373 if (new_dentry
== trap
)
2376 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
2377 new_dir
->d_inode
, new_dentry
);
2383 unlock_rename(new_dir
, old_dir
);
2385 path_release(&newnd
);
2387 path_release(&oldnd
);
2392 asmlinkage
long sys_rename(const char __user
* oldname
, const char __user
* newname
)
2398 from
= getname(oldname
);
2400 return PTR_ERR(from
);
2401 to
= getname(newname
);
2402 error
= PTR_ERR(to
);
2404 error
= do_rename(from
,to
);
2411 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
, const char *link
)
2415 len
= PTR_ERR(link
);
2420 if (len
> (unsigned) buflen
)
2422 if (copy_to_user(buffer
, link
, len
))
2429 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2430 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2431 * using) it for any given inode is up to filesystem.
2433 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2435 struct nameidata nd
;
2439 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
2440 if (!IS_ERR(cookie
)) {
2441 int res
= vfs_readlink(dentry
, buffer
, buflen
, nd_get_link(&nd
));
2442 if (dentry
->d_inode
->i_op
->put_link
)
2443 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
2444 cookie
= ERR_PTR(res
);
2446 return PTR_ERR(cookie
);
2449 int vfs_follow_link(struct nameidata
*nd
, const char *link
)
2451 return __vfs_follow_link(nd
, link
);
2454 /* get the link contents into pagecache */
2455 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
2458 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
2459 page
= read_cache_page(mapping
, 0, (filler_t
*)mapping
->a_ops
->readpage
,
2463 wait_on_page_locked(page
);
2464 if (!PageUptodate(page
))
2470 page_cache_release(page
);
2471 return ERR_PTR(-EIO
);
2477 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2479 struct page
*page
= NULL
;
2480 char *s
= page_getlink(dentry
, &page
);
2481 int res
= vfs_readlink(dentry
,buffer
,buflen
,s
);
2484 page_cache_release(page
);
2489 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
2491 struct page
*page
= NULL
;
2492 nd_set_link(nd
, page_getlink(dentry
, &page
));
2496 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2498 struct page
*page
= cookie
;
2502 page_cache_release(page
);
2506 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
2508 struct address_space
*mapping
= inode
->i_mapping
;
2509 struct page
*page
= grab_cache_page(mapping
, 0);
2515 err
= mapping
->a_ops
->prepare_write(NULL
, page
, 0, len
-1);
2518 kaddr
= kmap_atomic(page
, KM_USER0
);
2519 memcpy(kaddr
, symname
, len
-1);
2520 kunmap_atomic(kaddr
, KM_USER0
);
2521 mapping
->a_ops
->commit_write(NULL
, page
, 0, len
-1);
2523 * Notice that we are _not_ going to block here - end of page is
2524 * unmapped, so this will only try to map the rest of page, see
2525 * that it is unmapped (typically even will not look into inode -
2526 * ->i_size will be enough for everything) and zero it out.
2527 * OTOH it's obviously correct and should make the page up-to-date.
2529 if (!PageUptodate(page
)) {
2530 err
= mapping
->a_ops
->readpage(NULL
, page
);
2531 wait_on_page_locked(page
);
2535 page_cache_release(page
);
2538 mark_inode_dirty(inode
);
2542 page_cache_release(page
);
2547 struct inode_operations page_symlink_inode_operations
= {
2548 .readlink
= generic_readlink
,
2549 .follow_link
= page_follow_link_light
,
2550 .put_link
= page_put_link
,
2553 EXPORT_SYMBOL(__user_walk
);
2554 EXPORT_SYMBOL(follow_down
);
2555 EXPORT_SYMBOL(follow_up
);
2556 EXPORT_SYMBOL(get_write_access
); /* binfmt_aout */
2557 EXPORT_SYMBOL(getname
);
2558 EXPORT_SYMBOL(lock_rename
);
2559 EXPORT_SYMBOL(lookup_hash
);
2560 EXPORT_SYMBOL(lookup_one_len
);
2561 EXPORT_SYMBOL(page_follow_link_light
);
2562 EXPORT_SYMBOL(page_put_link
);
2563 EXPORT_SYMBOL(page_readlink
);
2564 EXPORT_SYMBOL(page_symlink
);
2565 EXPORT_SYMBOL(page_symlink_inode_operations
);
2566 EXPORT_SYMBOL(path_lookup
);
2567 EXPORT_SYMBOL(path_release
);
2568 EXPORT_SYMBOL(path_walk
);
2569 EXPORT_SYMBOL(permission
);
2570 EXPORT_SYMBOL(vfs_permission
);
2571 EXPORT_SYMBOL(file_permission
);
2572 EXPORT_SYMBOL(unlock_rename
);
2573 EXPORT_SYMBOL(vfs_create
);
2574 EXPORT_SYMBOL(vfs_follow_link
);
2575 EXPORT_SYMBOL(vfs_link
);
2576 EXPORT_SYMBOL(vfs_mkdir
);
2577 EXPORT_SYMBOL(vfs_mknod
);
2578 EXPORT_SYMBOL(generic_permission
);
2579 EXPORT_SYMBOL(vfs_readlink
);
2580 EXPORT_SYMBOL(vfs_rename
);
2581 EXPORT_SYMBOL(vfs_rmdir
);
2582 EXPORT_SYMBOL(vfs_symlink
);
2583 EXPORT_SYMBOL(vfs_unlink
);
2584 EXPORT_SYMBOL(dentry_unhash
);
2585 EXPORT_SYMBOL(generic_readlink
);