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 * get_write_access() gets write permission for a file.
261 * put_write_access() releases this write permission.
262 * This is used for regular files.
263 * We cannot support write (and maybe mmap read-write shared) accesses and
264 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
265 * can have the following values:
266 * 0: no writers, no VM_DENYWRITE mappings
267 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
268 * > 0: (i_writecount) users are writing to the file.
270 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
271 * except for the cases where we don't hold i_writecount yet. Then we need to
272 * use {get,deny}_write_access() - these functions check the sign and refuse
273 * to do the change if sign is wrong. Exclusion between them is provided by
274 * the inode->i_lock spinlock.
277 int get_write_access(struct inode
* inode
)
279 spin_lock(&inode
->i_lock
);
280 if (atomic_read(&inode
->i_writecount
) < 0) {
281 spin_unlock(&inode
->i_lock
);
284 atomic_inc(&inode
->i_writecount
);
285 spin_unlock(&inode
->i_lock
);
290 int deny_write_access(struct file
* file
)
292 struct inode
*inode
= file
->f_dentry
->d_inode
;
294 spin_lock(&inode
->i_lock
);
295 if (atomic_read(&inode
->i_writecount
) > 0) {
296 spin_unlock(&inode
->i_lock
);
299 atomic_dec(&inode
->i_writecount
);
300 spin_unlock(&inode
->i_lock
);
305 void path_release(struct nameidata
*nd
)
312 * umount() mustn't call path_release()/mntput() as that would clear
315 void path_release_on_umount(struct nameidata
*nd
)
318 mntput_no_expire(nd
->mnt
);
322 * release_open_intent - free up open intent resources
323 * @nd: pointer to nameidata
325 void release_open_intent(struct nameidata
*nd
)
327 if (nd
->intent
.open
.file
->f_dentry
== NULL
)
328 put_filp(nd
->intent
.open
.file
);
330 fput(nd
->intent
.open
.file
);
334 * Internal lookup() using the new generic dcache.
337 static struct dentry
* cached_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
339 struct dentry
* dentry
= __d_lookup(parent
, name
);
341 /* lockess __d_lookup may fail due to concurrent d_move()
342 * in some unrelated directory, so try with d_lookup
345 dentry
= d_lookup(parent
, name
);
347 if (dentry
&& dentry
->d_op
&& dentry
->d_op
->d_revalidate
) {
348 if (!dentry
->d_op
->d_revalidate(dentry
, nd
) && !d_invalidate(dentry
)) {
357 * Short-cut version of permission(), for calling by
358 * path_walk(), when dcache lock is held. Combines parts
359 * of permission() and generic_permission(), and tests ONLY for
360 * MAY_EXEC permission.
362 * If appropriate, check DAC only. If not appropriate, or
363 * short-cut DAC fails, then call permission() to do more
364 * complete permission check.
366 static inline int exec_permission_lite(struct inode
*inode
,
367 struct nameidata
*nd
)
369 umode_t mode
= inode
->i_mode
;
371 if (inode
->i_op
&& inode
->i_op
->permission
)
374 if (current
->fsuid
== inode
->i_uid
)
376 else if (in_group_p(inode
->i_gid
))
382 if ((inode
->i_mode
& S_IXUGO
) && capable(CAP_DAC_OVERRIDE
))
385 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_OVERRIDE
))
388 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_READ_SEARCH
))
393 return security_inode_permission(inode
, MAY_EXEC
, nd
);
397 * This is called when everything else fails, and we actually have
398 * to go to the low-level filesystem to find out what we should do..
400 * We get the directory semaphore, and after getting that we also
401 * make sure that nobody added the entry to the dcache in the meantime..
404 static struct dentry
* real_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
406 struct dentry
* result
;
407 struct inode
*dir
= parent
->d_inode
;
411 * First re-do the cached lookup just in case it was created
412 * while we waited for the directory semaphore..
414 * FIXME! This could use version numbering or similar to
415 * avoid unnecessary cache lookups.
417 * The "dcache_lock" is purely to protect the RCU list walker
418 * from concurrent renames at this point (we mustn't get false
419 * negatives from the RCU list walk here, unlike the optimistic
422 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
424 result
= d_lookup(parent
, name
);
426 struct dentry
* dentry
= d_alloc(parent
, name
);
427 result
= ERR_PTR(-ENOMEM
);
429 result
= dir
->i_op
->lookup(dir
, dentry
, nd
);
440 * Uhhuh! Nasty case: the cache was re-populated while
441 * we waited on the semaphore. Need to revalidate.
444 if (result
->d_op
&& result
->d_op
->d_revalidate
) {
445 if (!result
->d_op
->d_revalidate(result
, nd
) && !d_invalidate(result
)) {
447 result
= ERR_PTR(-ENOENT
);
453 static int __emul_lookup_dentry(const char *, struct nameidata
*);
457 walk_init_root(const char *name
, struct nameidata
*nd
)
459 read_lock(¤t
->fs
->lock
);
460 if (current
->fs
->altroot
&& !(nd
->flags
& LOOKUP_NOALT
)) {
461 nd
->mnt
= mntget(current
->fs
->altrootmnt
);
462 nd
->dentry
= dget(current
->fs
->altroot
);
463 read_unlock(¤t
->fs
->lock
);
464 if (__emul_lookup_dentry(name
,nd
))
466 read_lock(¤t
->fs
->lock
);
468 nd
->mnt
= mntget(current
->fs
->rootmnt
);
469 nd
->dentry
= dget(current
->fs
->root
);
470 read_unlock(¤t
->fs
->lock
);
474 static inline int __vfs_follow_link(struct nameidata
*nd
, const char *link
)
483 if (!walk_init_root(link
, nd
))
484 /* weird __emul_prefix() stuff did it */
487 res
= link_path_walk(link
, nd
);
489 if (nd
->depth
|| res
|| nd
->last_type
!=LAST_NORM
)
492 * If it is an iterative symlinks resolution in open_namei() we
493 * have to copy the last component. And all that crap because of
494 * bloody create() on broken symlinks. Furrfu...
497 if (unlikely(!name
)) {
501 strcpy(name
, nd
->last
.name
);
502 nd
->last
.name
= name
;
506 return PTR_ERR(link
);
510 struct vfsmount
*mnt
;
511 struct dentry
*dentry
;
514 static inline int __do_follow_link(struct path
*path
, struct nameidata
*nd
)
518 struct dentry
*dentry
= path
->dentry
;
520 touch_atime(path
->mnt
, dentry
);
521 nd_set_link(nd
, NULL
);
523 if (path
->mnt
== nd
->mnt
)
525 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
526 error
= PTR_ERR(cookie
);
527 if (!IS_ERR(cookie
)) {
528 char *s
= nd_get_link(nd
);
531 error
= __vfs_follow_link(nd
, s
);
532 if (dentry
->d_inode
->i_op
->put_link
)
533 dentry
->d_inode
->i_op
->put_link(dentry
, nd
, cookie
);
541 static inline void dput_path(struct path
*path
, struct nameidata
*nd
)
544 if (path
->mnt
!= nd
->mnt
)
548 static inline void path_to_nameidata(struct path
*path
, struct nameidata
*nd
)
551 if (nd
->mnt
!= path
->mnt
)
554 nd
->dentry
= path
->dentry
;
558 * This limits recursive symlink follows to 8, while
559 * limiting consecutive symlinks to 40.
561 * Without that kind of total limit, nasty chains of consecutive
562 * symlinks can cause almost arbitrarily long lookups.
564 static inline int do_follow_link(struct path
*path
, struct nameidata
*nd
)
567 if (current
->link_count
>= MAX_NESTED_LINKS
)
569 if (current
->total_link_count
>= 40)
571 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
573 err
= security_inode_follow_link(path
->dentry
, nd
);
576 current
->link_count
++;
577 current
->total_link_count
++;
579 err
= __do_follow_link(path
, nd
);
580 current
->link_count
--;
589 int follow_up(struct vfsmount
**mnt
, struct dentry
**dentry
)
591 struct vfsmount
*parent
;
592 struct dentry
*mountpoint
;
593 spin_lock(&vfsmount_lock
);
594 parent
=(*mnt
)->mnt_parent
;
595 if (parent
== *mnt
) {
596 spin_unlock(&vfsmount_lock
);
600 mountpoint
=dget((*mnt
)->mnt_mountpoint
);
601 spin_unlock(&vfsmount_lock
);
603 *dentry
= mountpoint
;
609 /* no need for dcache_lock, as serialization is taken care in
612 static int __follow_mount(struct path
*path
)
615 while (d_mountpoint(path
->dentry
)) {
616 struct vfsmount
*mounted
= lookup_mnt(path
->mnt
, path
->dentry
);
623 path
->dentry
= dget(mounted
->mnt_root
);
629 static void follow_mount(struct vfsmount
**mnt
, struct dentry
**dentry
)
631 while (d_mountpoint(*dentry
)) {
632 struct vfsmount
*mounted
= lookup_mnt(*mnt
, *dentry
);
638 *dentry
= dget(mounted
->mnt_root
);
642 /* no need for dcache_lock, as serialization is taken care in
645 int follow_down(struct vfsmount
**mnt
, struct dentry
**dentry
)
647 struct vfsmount
*mounted
;
649 mounted
= lookup_mnt(*mnt
, *dentry
);
654 *dentry
= dget(mounted
->mnt_root
);
660 static inline void follow_dotdot(struct nameidata
*nd
)
663 struct vfsmount
*parent
;
664 struct dentry
*old
= nd
->dentry
;
666 read_lock(¤t
->fs
->lock
);
667 if (nd
->dentry
== current
->fs
->root
&&
668 nd
->mnt
== current
->fs
->rootmnt
) {
669 read_unlock(¤t
->fs
->lock
);
672 read_unlock(¤t
->fs
->lock
);
673 spin_lock(&dcache_lock
);
674 if (nd
->dentry
!= nd
->mnt
->mnt_root
) {
675 nd
->dentry
= dget(nd
->dentry
->d_parent
);
676 spin_unlock(&dcache_lock
);
680 spin_unlock(&dcache_lock
);
681 spin_lock(&vfsmount_lock
);
682 parent
= nd
->mnt
->mnt_parent
;
683 if (parent
== nd
->mnt
) {
684 spin_unlock(&vfsmount_lock
);
688 nd
->dentry
= dget(nd
->mnt
->mnt_mountpoint
);
689 spin_unlock(&vfsmount_lock
);
694 follow_mount(&nd
->mnt
, &nd
->dentry
);
698 * It's more convoluted than I'd like it to be, but... it's still fairly
699 * small and for now I'd prefer to have fast path as straight as possible.
700 * It _is_ time-critical.
702 static int do_lookup(struct nameidata
*nd
, struct qstr
*name
,
705 struct vfsmount
*mnt
= nd
->mnt
;
706 struct dentry
*dentry
= __d_lookup(nd
->dentry
, name
);
710 if (dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
711 goto need_revalidate
;
714 path
->dentry
= dentry
;
715 __follow_mount(path
);
719 dentry
= real_lookup(nd
->dentry
, name
, nd
);
725 if (dentry
->d_op
->d_revalidate(dentry
, nd
))
727 if (d_invalidate(dentry
))
733 return PTR_ERR(dentry
);
738 * This is the basic name resolution function, turning a pathname into
739 * the final dentry. We expect 'base' to be positive and a directory.
741 * Returns 0 and nd will have valid dentry and mnt on success.
742 * Returns error and drops reference to input namei data on failure.
744 static fastcall
int __link_path_walk(const char * name
, struct nameidata
*nd
)
749 unsigned int lookup_flags
= nd
->flags
;
756 inode
= nd
->dentry
->d_inode
;
758 lookup_flags
= LOOKUP_FOLLOW
;
760 /* At this point we know we have a real path component. */
766 nd
->flags
|= LOOKUP_CONTINUE
;
767 err
= exec_permission_lite(inode
, nd
);
768 if (err
== -EAGAIN
) {
769 err
= permission(inode
, MAY_EXEC
, nd
);
775 c
= *(const unsigned char *)name
;
777 hash
= init_name_hash();
780 hash
= partial_name_hash(c
, hash
);
781 c
= *(const unsigned char *)name
;
782 } while (c
&& (c
!= '/'));
783 this.len
= name
- (const char *) this.name
;
784 this.hash
= end_name_hash(hash
);
786 /* remove trailing slashes? */
789 while (*++name
== '/');
791 goto last_with_slashes
;
794 * "." and ".." are special - ".." especially so because it has
795 * to be able to know about the current root directory and
796 * parent relationships.
798 if (this.name
[0] == '.') switch (this.len
) {
802 if (this.name
[1] != '.')
805 inode
= nd
->dentry
->d_inode
;
811 * See if the low-level filesystem might want
812 * to use its own hash..
814 if (nd
->dentry
->d_op
&& nd
->dentry
->d_op
->d_hash
) {
815 err
= nd
->dentry
->d_op
->d_hash(nd
->dentry
, &this);
819 /* This does the actual lookups.. */
820 err
= do_lookup(nd
, &this, &next
);
825 inode
= next
.dentry
->d_inode
;
832 if (inode
->i_op
->follow_link
) {
833 err
= do_follow_link(&next
, nd
);
837 inode
= nd
->dentry
->d_inode
;
844 path_to_nameidata(&next
, nd
);
846 if (!inode
->i_op
->lookup
)
849 /* here ends the main loop */
852 lookup_flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
854 nd
->flags
&= ~LOOKUP_CONTINUE
;
855 if (lookup_flags
& LOOKUP_PARENT
)
857 if (this.name
[0] == '.') switch (this.len
) {
861 if (this.name
[1] != '.')
864 inode
= nd
->dentry
->d_inode
;
869 if (nd
->dentry
->d_op
&& nd
->dentry
->d_op
->d_hash
) {
870 err
= nd
->dentry
->d_op
->d_hash(nd
->dentry
, &this);
874 err
= do_lookup(nd
, &this, &next
);
877 inode
= next
.dentry
->d_inode
;
878 if ((lookup_flags
& LOOKUP_FOLLOW
)
879 && inode
&& inode
->i_op
&& inode
->i_op
->follow_link
) {
880 err
= do_follow_link(&next
, nd
);
883 inode
= nd
->dentry
->d_inode
;
885 path_to_nameidata(&next
, nd
);
889 if (lookup_flags
& LOOKUP_DIRECTORY
) {
891 if (!inode
->i_op
|| !inode
->i_op
->lookup
)
897 nd
->last_type
= LAST_NORM
;
898 if (this.name
[0] != '.')
901 nd
->last_type
= LAST_DOT
;
902 else if (this.len
== 2 && this.name
[1] == '.')
903 nd
->last_type
= LAST_DOTDOT
;
908 * We bypassed the ordinary revalidation routines.
909 * We may need to check the cached dentry for staleness.
911 if (nd
->dentry
&& nd
->dentry
->d_sb
&&
912 (nd
->dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
)) {
914 /* Note: we do not d_invalidate() */
915 if (!nd
->dentry
->d_op
->d_revalidate(nd
->dentry
, nd
))
921 dput_path(&next
, nd
);
930 * Wrapper to retry pathname resolution whenever the underlying
931 * file system returns an ESTALE.
933 * Retry the whole path once, forcing real lookup requests
934 * instead of relying on the dcache.
936 int fastcall
link_path_walk(const char *name
, struct nameidata
*nd
)
938 struct nameidata save
= *nd
;
941 /* make sure the stuff we saved doesn't go away */
945 result
= __link_path_walk(name
, nd
);
946 if (result
== -ESTALE
) {
950 nd
->flags
|= LOOKUP_REVAL
;
951 result
= __link_path_walk(name
, nd
);
960 int fastcall
path_walk(const char * name
, struct nameidata
*nd
)
962 current
->total_link_count
= 0;
963 return link_path_walk(name
, nd
);
967 * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
968 * everything is done. Returns 0 and drops input nd, if lookup failed;
970 static int __emul_lookup_dentry(const char *name
, struct nameidata
*nd
)
972 if (path_walk(name
, nd
))
973 return 0; /* something went wrong... */
975 if (!nd
->dentry
->d_inode
|| S_ISDIR(nd
->dentry
->d_inode
->i_mode
)) {
976 struct dentry
*old_dentry
= nd
->dentry
;
977 struct vfsmount
*old_mnt
= nd
->mnt
;
978 struct qstr last
= nd
->last
;
979 int last_type
= nd
->last_type
;
981 * NAME was not found in alternate root or it's a directory. Try to find
982 * it in the normal root:
984 nd
->last_type
= LAST_ROOT
;
985 read_lock(¤t
->fs
->lock
);
986 nd
->mnt
= mntget(current
->fs
->rootmnt
);
987 nd
->dentry
= dget(current
->fs
->root
);
988 read_unlock(¤t
->fs
->lock
);
989 if (path_walk(name
, nd
) == 0) {
990 if (nd
->dentry
->d_inode
) {
997 nd
->dentry
= old_dentry
;
1000 nd
->last_type
= last_type
;
1005 void set_fs_altroot(void)
1007 char *emul
= __emul_prefix();
1008 struct nameidata nd
;
1009 struct vfsmount
*mnt
= NULL
, *oldmnt
;
1010 struct dentry
*dentry
= NULL
, *olddentry
;
1015 err
= path_lookup(emul
, LOOKUP_FOLLOW
|LOOKUP_DIRECTORY
|LOOKUP_NOALT
, &nd
);
1021 write_lock(¤t
->fs
->lock
);
1022 oldmnt
= current
->fs
->altrootmnt
;
1023 olddentry
= current
->fs
->altroot
;
1024 current
->fs
->altrootmnt
= mnt
;
1025 current
->fs
->altroot
= dentry
;
1026 write_unlock(¤t
->fs
->lock
);
1033 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1034 int fastcall
path_lookup(const char *name
, unsigned int flags
, struct nameidata
*nd
)
1038 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1042 read_lock(¤t
->fs
->lock
);
1044 if (current
->fs
->altroot
&& !(nd
->flags
& LOOKUP_NOALT
)) {
1045 nd
->mnt
= mntget(current
->fs
->altrootmnt
);
1046 nd
->dentry
= dget(current
->fs
->altroot
);
1047 read_unlock(¤t
->fs
->lock
);
1048 if (__emul_lookup_dentry(name
,nd
))
1049 goto out
; /* found in altroot */
1050 read_lock(¤t
->fs
->lock
);
1052 nd
->mnt
= mntget(current
->fs
->rootmnt
);
1053 nd
->dentry
= dget(current
->fs
->root
);
1055 nd
->mnt
= mntget(current
->fs
->pwdmnt
);
1056 nd
->dentry
= dget(current
->fs
->pwd
);
1058 read_unlock(¤t
->fs
->lock
);
1059 current
->total_link_count
= 0;
1060 retval
= link_path_walk(name
, nd
);
1062 if (unlikely(current
->audit_context
1063 && nd
&& nd
->dentry
&& nd
->dentry
->d_inode
))
1064 audit_inode(name
, nd
->dentry
->d_inode
, flags
);
1068 static int __path_lookup_intent_open(const char *name
, unsigned int lookup_flags
,
1069 struct nameidata
*nd
, int open_flags
, int create_mode
)
1071 struct file
*filp
= get_empty_filp();
1076 nd
->intent
.open
.file
= filp
;
1077 nd
->intent
.open
.flags
= open_flags
;
1078 nd
->intent
.open
.create_mode
= create_mode
;
1079 err
= path_lookup(name
, lookup_flags
|LOOKUP_OPEN
, nd
);
1080 if (IS_ERR(nd
->intent
.open
.file
)) {
1082 err
= PTR_ERR(nd
->intent
.open
.file
);
1085 } else if (err
!= 0)
1086 release_open_intent(nd
);
1091 * path_lookup_open - lookup a file path with open intent
1092 * @name: pointer to file name
1093 * @lookup_flags: lookup intent flags
1094 * @nd: pointer to nameidata
1095 * @open_flags: open intent flags
1097 int path_lookup_open(const char *name
, unsigned int lookup_flags
,
1098 struct nameidata
*nd
, int open_flags
)
1100 return __path_lookup_intent_open(name
, lookup_flags
, nd
,
1105 * path_lookup_create - lookup a file path with open + create intent
1106 * @name: pointer to file name
1107 * @lookup_flags: lookup intent flags
1108 * @nd: pointer to nameidata
1109 * @open_flags: open intent flags
1110 * @create_mode: create intent flags
1112 int path_lookup_create(const char *name
, unsigned int lookup_flags
,
1113 struct nameidata
*nd
, int open_flags
, int create_mode
)
1115 return __path_lookup_intent_open(name
, lookup_flags
|LOOKUP_CREATE
, nd
,
1116 open_flags
, create_mode
);
1119 int __user_path_lookup_open(const char __user
*name
, unsigned int lookup_flags
,
1120 struct nameidata
*nd
, int open_flags
)
1122 char *tmp
= getname(name
);
1123 int err
= PTR_ERR(tmp
);
1126 err
= __path_lookup_intent_open(tmp
, lookup_flags
, nd
, open_flags
, 0);
1133 * Restricted form of lookup. Doesn't follow links, single-component only,
1134 * needs parent already locked. Doesn't follow mounts.
1137 static struct dentry
* __lookup_hash(struct qstr
*name
, struct dentry
* base
, struct nameidata
*nd
)
1139 struct dentry
* dentry
;
1140 struct inode
*inode
;
1143 inode
= base
->d_inode
;
1144 err
= permission(inode
, MAY_EXEC
, nd
);
1145 dentry
= ERR_PTR(err
);
1150 * See if the low-level filesystem might want
1151 * to use its own hash..
1153 if (base
->d_op
&& base
->d_op
->d_hash
) {
1154 err
= base
->d_op
->d_hash(base
, name
);
1155 dentry
= ERR_PTR(err
);
1160 dentry
= cached_lookup(base
, name
, nd
);
1162 struct dentry
*new = d_alloc(base
, name
);
1163 dentry
= ERR_PTR(-ENOMEM
);
1166 dentry
= inode
->i_op
->lookup(inode
, new, nd
);
1176 struct dentry
* lookup_hash(struct qstr
*name
, struct dentry
* base
)
1178 return __lookup_hash(name
, base
, NULL
);
1182 struct dentry
* lookup_one_len(const char * name
, struct dentry
* base
, int len
)
1193 hash
= init_name_hash();
1195 c
= *(const unsigned char *)name
++;
1196 if (c
== '/' || c
== '\0')
1198 hash
= partial_name_hash(c
, hash
);
1200 this.hash
= end_name_hash(hash
);
1202 return lookup_hash(&this, base
);
1204 return ERR_PTR(-EACCES
);
1210 * is used by most simple commands to get the inode of a specified name.
1211 * Open, link etc use their own routines, but this is enough for things
1214 * namei exists in two versions: namei/lnamei. The only difference is
1215 * that namei follows links, while lnamei does not.
1218 int fastcall
__user_walk(const char __user
*name
, unsigned flags
, struct nameidata
*nd
)
1220 char *tmp
= getname(name
);
1221 int err
= PTR_ERR(tmp
);
1224 err
= path_lookup(tmp
, flags
, nd
);
1231 * It's inline, so penalty for filesystems that don't use sticky bit is
1234 static inline int check_sticky(struct inode
*dir
, struct inode
*inode
)
1236 if (!(dir
->i_mode
& S_ISVTX
))
1238 if (inode
->i_uid
== current
->fsuid
)
1240 if (dir
->i_uid
== current
->fsuid
)
1242 return !capable(CAP_FOWNER
);
1246 * Check whether we can remove a link victim from directory dir, check
1247 * whether the type of victim is right.
1248 * 1. We can't do it if dir is read-only (done in permission())
1249 * 2. We should have write and exec permissions on dir
1250 * 3. We can't remove anything from append-only dir
1251 * 4. We can't do anything with immutable dir (done in permission())
1252 * 5. If the sticky bit on dir is set we should either
1253 * a. be owner of dir, or
1254 * b. be owner of victim, or
1255 * c. have CAP_FOWNER capability
1256 * 6. If the victim is append-only or immutable we can't do antyhing with
1257 * links pointing to it.
1258 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1259 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1260 * 9. We can't remove a root or mountpoint.
1261 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1262 * nfs_async_unlink().
1264 static inline int may_delete(struct inode
*dir
,struct dentry
*victim
,int isdir
)
1268 if (!victim
->d_inode
)
1271 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
1273 error
= permission(dir
,MAY_WRITE
| MAY_EXEC
, NULL
);
1278 if (check_sticky(dir
, victim
->d_inode
)||IS_APPEND(victim
->d_inode
)||
1279 IS_IMMUTABLE(victim
->d_inode
))
1282 if (!S_ISDIR(victim
->d_inode
->i_mode
))
1284 if (IS_ROOT(victim
))
1286 } else if (S_ISDIR(victim
->d_inode
->i_mode
))
1288 if (IS_DEADDIR(dir
))
1290 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
1295 /* Check whether we can create an object with dentry child in directory
1297 * 1. We can't do it if child already exists (open has special treatment for
1298 * this case, but since we are inlined it's OK)
1299 * 2. We can't do it if dir is read-only (done in permission())
1300 * 3. We should have write and exec permissions on dir
1301 * 4. We can't do it if dir is immutable (done in permission())
1303 static inline int may_create(struct inode
*dir
, struct dentry
*child
,
1304 struct nameidata
*nd
)
1308 if (IS_DEADDIR(dir
))
1310 return permission(dir
,MAY_WRITE
| MAY_EXEC
, nd
);
1314 * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security
1317 * O_DIRECTORY translates into forcing a directory lookup.
1319 static inline int lookup_flags(unsigned int f
)
1321 unsigned long retval
= LOOKUP_FOLLOW
;
1324 retval
&= ~LOOKUP_FOLLOW
;
1326 if ((f
& (O_CREAT
|O_EXCL
)) == (O_CREAT
|O_EXCL
))
1327 retval
&= ~LOOKUP_FOLLOW
;
1329 if (f
& O_DIRECTORY
)
1330 retval
|= LOOKUP_DIRECTORY
;
1336 * p1 and p2 should be directories on the same fs.
1338 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
1343 down(&p1
->d_inode
->i_sem
);
1347 down(&p1
->d_inode
->i_sb
->s_vfs_rename_sem
);
1349 for (p
= p1
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1350 if (p
->d_parent
== p2
) {
1351 down(&p2
->d_inode
->i_sem
);
1352 down(&p1
->d_inode
->i_sem
);
1357 for (p
= p2
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1358 if (p
->d_parent
== p1
) {
1359 down(&p1
->d_inode
->i_sem
);
1360 down(&p2
->d_inode
->i_sem
);
1365 down(&p1
->d_inode
->i_sem
);
1366 down(&p2
->d_inode
->i_sem
);
1370 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
1372 up(&p1
->d_inode
->i_sem
);
1374 up(&p2
->d_inode
->i_sem
);
1375 up(&p1
->d_inode
->i_sb
->s_vfs_rename_sem
);
1379 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1380 struct nameidata
*nd
)
1382 int error
= may_create(dir
, dentry
, nd
);
1387 if (!dir
->i_op
|| !dir
->i_op
->create
)
1388 return -EACCES
; /* shouldn't it be ENOSYS? */
1391 error
= security_inode_create(dir
, dentry
, mode
);
1395 error
= dir
->i_op
->create(dir
, dentry
, mode
, nd
);
1397 fsnotify_create(dir
, dentry
->d_name
.name
);
1401 int may_open(struct nameidata
*nd
, int acc_mode
, int flag
)
1403 struct dentry
*dentry
= nd
->dentry
;
1404 struct inode
*inode
= dentry
->d_inode
;
1410 if (S_ISLNK(inode
->i_mode
))
1413 if (S_ISDIR(inode
->i_mode
) && (flag
& FMODE_WRITE
))
1416 error
= permission(inode
, acc_mode
, nd
);
1421 * FIFO's, sockets and device files are special: they don't
1422 * actually live on the filesystem itself, and as such you
1423 * can write to them even if the filesystem is read-only.
1425 if (S_ISFIFO(inode
->i_mode
) || S_ISSOCK(inode
->i_mode
)) {
1427 } else if (S_ISBLK(inode
->i_mode
) || S_ISCHR(inode
->i_mode
)) {
1428 if (nd
->mnt
->mnt_flags
& MNT_NODEV
)
1432 } else if (IS_RDONLY(inode
) && (flag
& FMODE_WRITE
))
1435 * An append-only file must be opened in append mode for writing.
1437 if (IS_APPEND(inode
)) {
1438 if ((flag
& FMODE_WRITE
) && !(flag
& O_APPEND
))
1444 /* O_NOATIME can only be set by the owner or superuser */
1445 if (flag
& O_NOATIME
)
1446 if (current
->fsuid
!= inode
->i_uid
&& !capable(CAP_FOWNER
))
1450 * Ensure there are no outstanding leases on the file.
1452 error
= break_lease(inode
, flag
);
1456 if (flag
& O_TRUNC
) {
1457 error
= get_write_access(inode
);
1462 * Refuse to truncate files with mandatory locks held on them.
1464 error
= locks_verify_locked(inode
);
1468 error
= do_truncate(dentry
, 0);
1470 put_write_access(inode
);
1474 if (flag
& FMODE_WRITE
)
1483 * namei for open - this is in fact almost the whole open-routine.
1485 * Note that the low bits of "flag" aren't the same as in the open
1486 * system call - they are 00 - no permissions needed
1487 * 01 - read permission needed
1488 * 10 - write permission needed
1489 * 11 - read/write permissions needed
1490 * which is a lot more logical, and also allows the "no perm" needed
1491 * for symlinks (where the permissions are checked later).
1494 int open_namei(const char * pathname
, int flag
, int mode
, struct nameidata
*nd
)
1496 int acc_mode
, error
;
1501 acc_mode
= ACC_MODE(flag
);
1503 /* O_TRUNC implies we need access checks for write permissions */
1505 acc_mode
|= MAY_WRITE
;
1507 /* Allow the LSM permission hook to distinguish append
1508 access from general write access. */
1509 if (flag
& O_APPEND
)
1510 acc_mode
|= MAY_APPEND
;
1513 * The simplest case - just a plain lookup.
1515 if (!(flag
& O_CREAT
)) {
1516 error
= path_lookup_open(pathname
, lookup_flags(flag
), nd
, flag
);
1523 * Create - we need to know the parent.
1525 error
= path_lookup_create(pathname
, LOOKUP_PARENT
, nd
, flag
, mode
);
1530 * We have the parent and last component. First of all, check
1531 * that we are not asked to creat(2) an obvious directory - that
1535 if (nd
->last_type
!= LAST_NORM
|| nd
->last
.name
[nd
->last
.len
])
1539 nd
->flags
&= ~LOOKUP_PARENT
;
1540 down(&dir
->d_inode
->i_sem
);
1541 path
.dentry
= __lookup_hash(&nd
->last
, nd
->dentry
, nd
);
1545 error
= PTR_ERR(path
.dentry
);
1546 if (IS_ERR(path
.dentry
)) {
1547 up(&dir
->d_inode
->i_sem
);
1551 /* Negative dentry, just create the file */
1552 if (!path
.dentry
->d_inode
) {
1553 if (!IS_POSIXACL(dir
->d_inode
))
1554 mode
&= ~current
->fs
->umask
;
1555 error
= vfs_create(dir
->d_inode
, path
.dentry
, mode
, nd
);
1556 up(&dir
->d_inode
->i_sem
);
1558 nd
->dentry
= path
.dentry
;
1561 /* Don't check for write permission, don't truncate */
1568 * It already exists.
1570 up(&dir
->d_inode
->i_sem
);
1576 if (__follow_mount(&path
)) {
1578 if (flag
& O_NOFOLLOW
)
1582 if (!path
.dentry
->d_inode
)
1584 if (path
.dentry
->d_inode
->i_op
&& path
.dentry
->d_inode
->i_op
->follow_link
)
1587 path_to_nameidata(&path
, nd
);
1589 if (path
.dentry
->d_inode
&& S_ISDIR(path
.dentry
->d_inode
->i_mode
))
1592 error
= may_open(nd
, acc_mode
, flag
);
1598 dput_path(&path
, nd
);
1600 if (!IS_ERR(nd
->intent
.open
.file
))
1601 release_open_intent(nd
);
1607 if (flag
& O_NOFOLLOW
)
1610 * This is subtle. Instead of calling do_follow_link() we do the
1611 * thing by hands. The reason is that this way we have zero link_count
1612 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1613 * After that we have the parent and last component, i.e.
1614 * we are in the same situation as after the first path_walk().
1615 * Well, almost - if the last component is normal we get its copy
1616 * stored in nd->last.name and we will have to putname() it when we
1617 * are done. Procfs-like symlinks just set LAST_BIND.
1619 nd
->flags
|= LOOKUP_PARENT
;
1620 error
= security_inode_follow_link(path
.dentry
, nd
);
1623 error
= __do_follow_link(&path
, nd
);
1626 nd
->flags
&= ~LOOKUP_PARENT
;
1627 if (nd
->last_type
== LAST_BIND
)
1630 if (nd
->last_type
!= LAST_NORM
)
1632 if (nd
->last
.name
[nd
->last
.len
]) {
1633 __putname(nd
->last
.name
);
1638 __putname(nd
->last
.name
);
1642 down(&dir
->d_inode
->i_sem
);
1643 path
.dentry
= __lookup_hash(&nd
->last
, nd
->dentry
, nd
);
1645 __putname(nd
->last
.name
);
1650 * lookup_create - lookup a dentry, creating it if it doesn't exist
1651 * @nd: nameidata info
1652 * @is_dir: directory flag
1654 * Simple function to lookup and return a dentry and create it
1655 * if it doesn't exist. Is SMP-safe.
1657 * Returns with nd->dentry->d_inode->i_sem locked.
1659 struct dentry
*lookup_create(struct nameidata
*nd
, int is_dir
)
1661 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
1663 down(&nd
->dentry
->d_inode
->i_sem
);
1665 * Yucky last component or no last component at all?
1666 * (foo/., foo/.., /////)
1668 if (nd
->last_type
!= LAST_NORM
)
1670 nd
->flags
&= ~LOOKUP_PARENT
;
1673 * Do the final lookup.
1675 dentry
= lookup_hash(&nd
->last
, nd
->dentry
);
1680 * Special case - lookup gave negative, but... we had foo/bar/
1681 * From the vfs_mknod() POV we just have a negative dentry -
1682 * all is fine. Let's be bastards - you had / on the end, you've
1683 * been asking for (non-existent) directory. -ENOENT for you.
1685 if (!is_dir
&& nd
->last
.name
[nd
->last
.len
] && !dentry
->d_inode
)
1690 dentry
= ERR_PTR(-ENOENT
);
1694 EXPORT_SYMBOL_GPL(lookup_create
);
1696 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1698 int error
= may_create(dir
, dentry
, NULL
);
1703 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
1706 if (!dir
->i_op
|| !dir
->i_op
->mknod
)
1709 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
1714 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
1716 fsnotify_create(dir
, dentry
->d_name
.name
);
1720 asmlinkage
long sys_mknod(const char __user
* filename
, int mode
, unsigned dev
)
1724 struct dentry
* dentry
;
1725 struct nameidata nd
;
1729 tmp
= getname(filename
);
1731 return PTR_ERR(tmp
);
1733 error
= path_lookup(tmp
, LOOKUP_PARENT
, &nd
);
1736 dentry
= lookup_create(&nd
, 0);
1737 error
= PTR_ERR(dentry
);
1739 if (!IS_POSIXACL(nd
.dentry
->d_inode
))
1740 mode
&= ~current
->fs
->umask
;
1741 if (!IS_ERR(dentry
)) {
1742 switch (mode
& S_IFMT
) {
1743 case 0: case S_IFREG
:
1744 error
= vfs_create(nd
.dentry
->d_inode
,dentry
,mode
,&nd
);
1746 case S_IFCHR
: case S_IFBLK
:
1747 error
= vfs_mknod(nd
.dentry
->d_inode
,dentry
,mode
,
1748 new_decode_dev(dev
));
1750 case S_IFIFO
: case S_IFSOCK
:
1751 error
= vfs_mknod(nd
.dentry
->d_inode
,dentry
,mode
,0);
1761 up(&nd
.dentry
->d_inode
->i_sem
);
1769 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
1771 int error
= may_create(dir
, dentry
, NULL
);
1776 if (!dir
->i_op
|| !dir
->i_op
->mkdir
)
1779 mode
&= (S_IRWXUGO
|S_ISVTX
);
1780 error
= security_inode_mkdir(dir
, dentry
, mode
);
1785 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
1787 fsnotify_mkdir(dir
, dentry
->d_name
.name
);
1791 asmlinkage
long sys_mkdir(const char __user
* pathname
, int mode
)
1796 tmp
= getname(pathname
);
1797 error
= PTR_ERR(tmp
);
1799 struct dentry
*dentry
;
1800 struct nameidata nd
;
1802 error
= path_lookup(tmp
, LOOKUP_PARENT
, &nd
);
1805 dentry
= lookup_create(&nd
, 1);
1806 error
= PTR_ERR(dentry
);
1807 if (!IS_ERR(dentry
)) {
1808 if (!IS_POSIXACL(nd
.dentry
->d_inode
))
1809 mode
&= ~current
->fs
->umask
;
1810 error
= vfs_mkdir(nd
.dentry
->d_inode
, dentry
, mode
);
1813 up(&nd
.dentry
->d_inode
->i_sem
);
1823 * We try to drop the dentry early: we should have
1824 * a usage count of 2 if we're the only user of this
1825 * dentry, and if that is true (possibly after pruning
1826 * the dcache), then we drop the dentry now.
1828 * A low-level filesystem can, if it choses, legally
1831 * if (!d_unhashed(dentry))
1834 * if it cannot handle the case of removing a directory
1835 * that is still in use by something else..
1837 void dentry_unhash(struct dentry
*dentry
)
1840 if (atomic_read(&dentry
->d_count
))
1841 shrink_dcache_parent(dentry
);
1842 spin_lock(&dcache_lock
);
1843 spin_lock(&dentry
->d_lock
);
1844 if (atomic_read(&dentry
->d_count
) == 2)
1846 spin_unlock(&dentry
->d_lock
);
1847 spin_unlock(&dcache_lock
);
1850 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
1852 int error
= may_delete(dir
, dentry
, 1);
1857 if (!dir
->i_op
|| !dir
->i_op
->rmdir
)
1862 down(&dentry
->d_inode
->i_sem
);
1863 dentry_unhash(dentry
);
1864 if (d_mountpoint(dentry
))
1867 error
= security_inode_rmdir(dir
, dentry
);
1869 error
= dir
->i_op
->rmdir(dir
, dentry
);
1871 dentry
->d_inode
->i_flags
|= S_DEAD
;
1874 up(&dentry
->d_inode
->i_sem
);
1883 asmlinkage
long sys_rmdir(const char __user
* pathname
)
1887 struct dentry
*dentry
;
1888 struct nameidata nd
;
1890 name
= getname(pathname
);
1892 return PTR_ERR(name
);
1894 error
= path_lookup(name
, LOOKUP_PARENT
, &nd
);
1898 switch(nd
.last_type
) {
1909 down(&nd
.dentry
->d_inode
->i_sem
);
1910 dentry
= lookup_hash(&nd
.last
, nd
.dentry
);
1911 error
= PTR_ERR(dentry
);
1912 if (!IS_ERR(dentry
)) {
1913 error
= vfs_rmdir(nd
.dentry
->d_inode
, dentry
);
1916 up(&nd
.dentry
->d_inode
->i_sem
);
1924 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
)
1926 int error
= may_delete(dir
, dentry
, 0);
1931 if (!dir
->i_op
|| !dir
->i_op
->unlink
)
1936 down(&dentry
->d_inode
->i_sem
);
1937 if (d_mountpoint(dentry
))
1940 error
= security_inode_unlink(dir
, dentry
);
1942 error
= dir
->i_op
->unlink(dir
, dentry
);
1944 up(&dentry
->d_inode
->i_sem
);
1946 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
1947 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
1955 * Make sure that the actual truncation of the file will occur outside its
1956 * directory's i_sem. Truncate can take a long time if there is a lot of
1957 * writeout happening, and we don't want to prevent access to the directory
1958 * while waiting on the I/O.
1960 asmlinkage
long sys_unlink(const char __user
* pathname
)
1964 struct dentry
*dentry
;
1965 struct nameidata nd
;
1966 struct inode
*inode
= NULL
;
1968 name
= getname(pathname
);
1970 return PTR_ERR(name
);
1972 error
= path_lookup(name
, LOOKUP_PARENT
, &nd
);
1976 if (nd
.last_type
!= LAST_NORM
)
1978 down(&nd
.dentry
->d_inode
->i_sem
);
1979 dentry
= lookup_hash(&nd
.last
, nd
.dentry
);
1980 error
= PTR_ERR(dentry
);
1981 if (!IS_ERR(dentry
)) {
1982 /* Why not before? Because we want correct error value */
1983 if (nd
.last
.name
[nd
.last
.len
])
1985 inode
= dentry
->d_inode
;
1987 atomic_inc(&inode
->i_count
);
1988 error
= vfs_unlink(nd
.dentry
->d_inode
, dentry
);
1992 up(&nd
.dentry
->d_inode
->i_sem
);
1994 iput(inode
); /* truncate the inode here */
2002 error
= !dentry
->d_inode
? -ENOENT
:
2003 S_ISDIR(dentry
->d_inode
->i_mode
) ? -EISDIR
: -ENOTDIR
;
2007 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
, int mode
)
2009 int error
= may_create(dir
, dentry
, NULL
);
2014 if (!dir
->i_op
|| !dir
->i_op
->symlink
)
2017 error
= security_inode_symlink(dir
, dentry
, oldname
);
2022 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
2024 fsnotify_create(dir
, dentry
->d_name
.name
);
2028 asmlinkage
long sys_symlink(const char __user
* oldname
, const char __user
* newname
)
2034 from
= getname(oldname
);
2036 return PTR_ERR(from
);
2037 to
= getname(newname
);
2038 error
= PTR_ERR(to
);
2040 struct dentry
*dentry
;
2041 struct nameidata nd
;
2043 error
= path_lookup(to
, LOOKUP_PARENT
, &nd
);
2046 dentry
= lookup_create(&nd
, 0);
2047 error
= PTR_ERR(dentry
);
2048 if (!IS_ERR(dentry
)) {
2049 error
= vfs_symlink(nd
.dentry
->d_inode
, dentry
, from
, S_IALLUGO
);
2052 up(&nd
.dentry
->d_inode
->i_sem
);
2061 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
)
2063 struct inode
*inode
= old_dentry
->d_inode
;
2069 error
= may_create(dir
, new_dentry
, NULL
);
2073 if (dir
->i_sb
!= inode
->i_sb
)
2077 * A link to an append-only or immutable file cannot be created.
2079 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
2081 if (!dir
->i_op
|| !dir
->i_op
->link
)
2083 if (S_ISDIR(old_dentry
->d_inode
->i_mode
))
2086 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
2090 down(&old_dentry
->d_inode
->i_sem
);
2092 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
2093 up(&old_dentry
->d_inode
->i_sem
);
2095 fsnotify_create(dir
, new_dentry
->d_name
.name
);
2100 * Hardlinks are often used in delicate situations. We avoid
2101 * security-related surprises by not following symlinks on the
2104 * We don't follow them on the oldname either to be compatible
2105 * with linux 2.0, and to avoid hard-linking to directories
2106 * and other special files. --ADM
2108 asmlinkage
long sys_link(const char __user
* oldname
, const char __user
* newname
)
2110 struct dentry
*new_dentry
;
2111 struct nameidata nd
, old_nd
;
2115 to
= getname(newname
);
2119 error
= __user_walk(oldname
, 0, &old_nd
);
2122 error
= path_lookup(to
, LOOKUP_PARENT
, &nd
);
2126 if (old_nd
.mnt
!= nd
.mnt
)
2128 new_dentry
= lookup_create(&nd
, 0);
2129 error
= PTR_ERR(new_dentry
);
2130 if (!IS_ERR(new_dentry
)) {
2131 error
= vfs_link(old_nd
.dentry
, nd
.dentry
->d_inode
, new_dentry
);
2134 up(&nd
.dentry
->d_inode
->i_sem
);
2138 path_release(&old_nd
);
2146 * The worst of all namespace operations - renaming directory. "Perverted"
2147 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2149 * a) we can get into loop creation. Check is done in is_subdir().
2150 * b) race potential - two innocent renames can create a loop together.
2151 * That's where 4.4 screws up. Current fix: serialization on
2152 * sb->s_vfs_rename_sem. We might be more accurate, but that's another
2154 * c) we have to lock _three_ objects - parents and victim (if it exists).
2155 * And that - after we got ->i_sem on parents (until then we don't know
2156 * whether the target exists). Solution: try to be smart with locking
2157 * order for inodes. We rely on the fact that tree topology may change
2158 * only under ->s_vfs_rename_sem _and_ that parent of the object we
2159 * move will be locked. Thus we can rank directories by the tree
2160 * (ancestors first) and rank all non-directories after them.
2161 * That works since everybody except rename does "lock parent, lookup,
2162 * lock child" and rename is under ->s_vfs_rename_sem.
2163 * HOWEVER, it relies on the assumption that any object with ->lookup()
2164 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2165 * we'd better make sure that there's no link(2) for them.
2166 * d) some filesystems don't support opened-but-unlinked directories,
2167 * either because of layout or because they are not ready to deal with
2168 * all cases correctly. The latter will be fixed (taking this sort of
2169 * stuff into VFS), but the former is not going away. Solution: the same
2170 * trick as in rmdir().
2171 * e) conversion from fhandle to dentry may come in the wrong moment - when
2172 * we are removing the target. Solution: we will have to grab ->i_sem
2173 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2174 * ->i_sem on parents, which works but leads to some truely excessive
2177 static int vfs_rename_dir(struct inode
*old_dir
, struct dentry
*old_dentry
,
2178 struct inode
*new_dir
, struct dentry
*new_dentry
)
2181 struct inode
*target
;
2184 * If we are going to change the parent - check write permissions,
2185 * we'll need to flip '..'.
2187 if (new_dir
!= old_dir
) {
2188 error
= permission(old_dentry
->d_inode
, MAY_WRITE
, NULL
);
2193 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2197 target
= new_dentry
->d_inode
;
2199 down(&target
->i_sem
);
2200 dentry_unhash(new_dentry
);
2202 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2205 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2208 target
->i_flags
|= S_DEAD
;
2210 if (d_unhashed(new_dentry
))
2211 d_rehash(new_dentry
);
2215 d_move(old_dentry
,new_dentry
);
2219 static int vfs_rename_other(struct inode
*old_dir
, struct dentry
*old_dentry
,
2220 struct inode
*new_dir
, struct dentry
*new_dentry
)
2222 struct inode
*target
;
2225 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2230 target
= new_dentry
->d_inode
;
2232 down(&target
->i_sem
);
2233 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2236 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2238 /* The following d_move() should become unconditional */
2239 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_ODD_RENAME
))
2240 d_move(old_dentry
, new_dentry
);
2248 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2249 struct inode
*new_dir
, struct dentry
*new_dentry
)
2252 int is_dir
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
2253 const char *old_name
;
2255 if (old_dentry
->d_inode
== new_dentry
->d_inode
)
2258 error
= may_delete(old_dir
, old_dentry
, is_dir
);
2262 if (!new_dentry
->d_inode
)
2263 error
= may_create(new_dir
, new_dentry
, NULL
);
2265 error
= may_delete(new_dir
, new_dentry
, is_dir
);
2269 if (!old_dir
->i_op
|| !old_dir
->i_op
->rename
)
2272 DQUOT_INIT(old_dir
);
2273 DQUOT_INIT(new_dir
);
2275 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
2278 error
= vfs_rename_dir(old_dir
,old_dentry
,new_dir
,new_dentry
);
2280 error
= vfs_rename_other(old_dir
,old_dentry
,new_dir
,new_dentry
);
2282 const char *new_name
= old_dentry
->d_name
.name
;
2283 fsnotify_move(old_dir
, new_dir
, old_name
, new_name
, is_dir
,
2284 new_dentry
->d_inode
, old_dentry
->d_inode
);
2286 fsnotify_oldname_free(old_name
);
2291 static inline int do_rename(const char * oldname
, const char * newname
)
2294 struct dentry
* old_dir
, * new_dir
;
2295 struct dentry
* old_dentry
, *new_dentry
;
2296 struct dentry
* trap
;
2297 struct nameidata oldnd
, newnd
;
2299 error
= path_lookup(oldname
, LOOKUP_PARENT
, &oldnd
);
2303 error
= path_lookup(newname
, LOOKUP_PARENT
, &newnd
);
2308 if (oldnd
.mnt
!= newnd
.mnt
)
2311 old_dir
= oldnd
.dentry
;
2313 if (oldnd
.last_type
!= LAST_NORM
)
2316 new_dir
= newnd
.dentry
;
2317 if (newnd
.last_type
!= LAST_NORM
)
2320 trap
= lock_rename(new_dir
, old_dir
);
2322 old_dentry
= lookup_hash(&oldnd
.last
, old_dir
);
2323 error
= PTR_ERR(old_dentry
);
2324 if (IS_ERR(old_dentry
))
2326 /* source must exist */
2328 if (!old_dentry
->d_inode
)
2330 /* unless the source is a directory trailing slashes give -ENOTDIR */
2331 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
)) {
2333 if (oldnd
.last
.name
[oldnd
.last
.len
])
2335 if (newnd
.last
.name
[newnd
.last
.len
])
2338 /* source should not be ancestor of target */
2340 if (old_dentry
== trap
)
2342 new_dentry
= lookup_hash(&newnd
.last
, new_dir
);
2343 error
= PTR_ERR(new_dentry
);
2344 if (IS_ERR(new_dentry
))
2346 /* target should not be an ancestor of source */
2348 if (new_dentry
== trap
)
2351 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
2352 new_dir
->d_inode
, new_dentry
);
2358 unlock_rename(new_dir
, old_dir
);
2360 path_release(&newnd
);
2362 path_release(&oldnd
);
2367 asmlinkage
long sys_rename(const char __user
* oldname
, const char __user
* newname
)
2373 from
= getname(oldname
);
2375 return PTR_ERR(from
);
2376 to
= getname(newname
);
2377 error
= PTR_ERR(to
);
2379 error
= do_rename(from
,to
);
2386 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
, const char *link
)
2390 len
= PTR_ERR(link
);
2395 if (len
> (unsigned) buflen
)
2397 if (copy_to_user(buffer
, link
, len
))
2404 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2405 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2406 * using) it for any given inode is up to filesystem.
2408 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2410 struct nameidata nd
;
2414 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
2415 if (!IS_ERR(cookie
)) {
2416 int res
= vfs_readlink(dentry
, buffer
, buflen
, nd_get_link(&nd
));
2417 if (dentry
->d_inode
->i_op
->put_link
)
2418 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
2419 cookie
= ERR_PTR(res
);
2421 return PTR_ERR(cookie
);
2424 int vfs_follow_link(struct nameidata
*nd
, const char *link
)
2426 return __vfs_follow_link(nd
, link
);
2429 /* get the link contents into pagecache */
2430 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
2433 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
2434 page
= read_cache_page(mapping
, 0, (filler_t
*)mapping
->a_ops
->readpage
,
2438 wait_on_page_locked(page
);
2439 if (!PageUptodate(page
))
2445 page_cache_release(page
);
2446 return ERR_PTR(-EIO
);
2452 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2454 struct page
*page
= NULL
;
2455 char *s
= page_getlink(dentry
, &page
);
2456 int res
= vfs_readlink(dentry
,buffer
,buflen
,s
);
2459 page_cache_release(page
);
2464 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
2466 struct page
*page
= NULL
;
2467 nd_set_link(nd
, page_getlink(dentry
, &page
));
2471 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2473 struct page
*page
= cookie
;
2477 page_cache_release(page
);
2481 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
2483 struct address_space
*mapping
= inode
->i_mapping
;
2484 struct page
*page
= grab_cache_page(mapping
, 0);
2490 err
= mapping
->a_ops
->prepare_write(NULL
, page
, 0, len
-1);
2493 kaddr
= kmap_atomic(page
, KM_USER0
);
2494 memcpy(kaddr
, symname
, len
-1);
2495 kunmap_atomic(kaddr
, KM_USER0
);
2496 mapping
->a_ops
->commit_write(NULL
, page
, 0, len
-1);
2498 * Notice that we are _not_ going to block here - end of page is
2499 * unmapped, so this will only try to map the rest of page, see
2500 * that it is unmapped (typically even will not look into inode -
2501 * ->i_size will be enough for everything) and zero it out.
2502 * OTOH it's obviously correct and should make the page up-to-date.
2504 if (!PageUptodate(page
)) {
2505 err
= mapping
->a_ops
->readpage(NULL
, page
);
2506 wait_on_page_locked(page
);
2510 page_cache_release(page
);
2513 mark_inode_dirty(inode
);
2517 page_cache_release(page
);
2522 struct inode_operations page_symlink_inode_operations
= {
2523 .readlink
= generic_readlink
,
2524 .follow_link
= page_follow_link_light
,
2525 .put_link
= page_put_link
,
2528 EXPORT_SYMBOL(__user_walk
);
2529 EXPORT_SYMBOL(follow_down
);
2530 EXPORT_SYMBOL(follow_up
);
2531 EXPORT_SYMBOL(get_write_access
); /* binfmt_aout */
2532 EXPORT_SYMBOL(getname
);
2533 EXPORT_SYMBOL(lock_rename
);
2534 EXPORT_SYMBOL(lookup_hash
);
2535 EXPORT_SYMBOL(lookup_one_len
);
2536 EXPORT_SYMBOL(page_follow_link_light
);
2537 EXPORT_SYMBOL(page_put_link
);
2538 EXPORT_SYMBOL(page_readlink
);
2539 EXPORT_SYMBOL(page_symlink
);
2540 EXPORT_SYMBOL(page_symlink_inode_operations
);
2541 EXPORT_SYMBOL(path_lookup
);
2542 EXPORT_SYMBOL(path_release
);
2543 EXPORT_SYMBOL(path_walk
);
2544 EXPORT_SYMBOL(permission
);
2545 EXPORT_SYMBOL(unlock_rename
);
2546 EXPORT_SYMBOL(vfs_create
);
2547 EXPORT_SYMBOL(vfs_follow_link
);
2548 EXPORT_SYMBOL(vfs_link
);
2549 EXPORT_SYMBOL(vfs_mkdir
);
2550 EXPORT_SYMBOL(vfs_mknod
);
2551 EXPORT_SYMBOL(generic_permission
);
2552 EXPORT_SYMBOL(vfs_readlink
);
2553 EXPORT_SYMBOL(vfs_rename
);
2554 EXPORT_SYMBOL(vfs_rmdir
);
2555 EXPORT_SYMBOL(vfs_symlink
);
2556 EXPORT_SYMBOL(vfs_unlink
);
2557 EXPORT_SYMBOL(dentry_unhash
);
2558 EXPORT_SYMBOL(generic_readlink
);