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/export.h>
19 #include <linux/kernel.h>
20 #include <linux/slab.h>
22 #include <linux/namei.h>
23 #include <linux/pagemap.h>
24 #include <linux/fsnotify.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/ima.h>
28 #include <linux/syscalls.h>
29 #include <linux/mount.h>
30 #include <linux/audit.h>
31 #include <linux/capability.h>
32 #include <linux/file.h>
33 #include <linux/fcntl.h>
34 #include <linux/device_cgroup.h>
35 #include <linux/fs_struct.h>
36 #include <linux/posix_acl.h>
37 #include <linux/hash.h>
38 #include <asm/uaccess.h>
43 /* [Feb-1997 T. Schoebel-Theuer]
44 * Fundamental changes in the pathname lookup mechanisms (namei)
45 * were necessary because of omirr. The reason is that omirr needs
46 * to know the _real_ pathname, not the user-supplied one, in case
47 * of symlinks (and also when transname replacements occur).
49 * The new code replaces the old recursive symlink resolution with
50 * an iterative one (in case of non-nested symlink chains). It does
51 * this with calls to <fs>_follow_link().
52 * As a side effect, dir_namei(), _namei() and follow_link() are now
53 * replaced with a single function lookup_dentry() that can handle all
54 * the special cases of the former code.
56 * With the new dcache, the pathname is stored at each inode, at least as
57 * long as the refcount of the inode is positive. As a side effect, the
58 * size of the dcache depends on the inode cache and thus is dynamic.
60 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
61 * resolution to correspond with current state of the code.
63 * Note that the symlink resolution is not *completely* iterative.
64 * There is still a significant amount of tail- and mid- recursion in
65 * the algorithm. Also, note that <fs>_readlink() is not used in
66 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
67 * may return different results than <fs>_follow_link(). Many virtual
68 * filesystems (including /proc) exhibit this behavior.
71 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
72 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
73 * and the name already exists in form of a symlink, try to create the new
74 * name indicated by the symlink. The old code always complained that the
75 * name already exists, due to not following the symlink even if its target
76 * is nonexistent. The new semantics affects also mknod() and link() when
77 * the name is a symlink pointing to a non-existent name.
79 * I don't know which semantics is the right one, since I have no access
80 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
81 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
82 * "old" one. Personally, I think the new semantics is much more logical.
83 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
84 * file does succeed in both HP-UX and SunOs, but not in Solaris
85 * and in the old Linux semantics.
88 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
89 * semantics. See the comments in "open_namei" and "do_link" below.
91 * [10-Sep-98 Alan Modra] Another symlink change.
94 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
95 * inside the path - always follow.
96 * in the last component in creation/removal/renaming - never follow.
97 * if LOOKUP_FOLLOW passed - follow.
98 * if the pathname has trailing slashes - follow.
99 * otherwise - don't follow.
100 * (applied in that order).
102 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
103 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
104 * During the 2.4 we need to fix the userland stuff depending on it -
105 * hopefully we will be able to get rid of that wart in 2.5. So far only
106 * XEmacs seems to be relying on it...
109 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
110 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
111 * any extra contention...
114 /* In order to reduce some races, while at the same time doing additional
115 * checking and hopefully speeding things up, we copy filenames to the
116 * kernel data space before using them..
118 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
119 * PATH_MAX includes the nul terminator --RR.
122 #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname))
125 getname_flags(const char __user
*filename
, int flags
, int *empty
)
127 struct filename
*result
;
131 result
= audit_reusename(filename
);
135 result
= __getname();
136 if (unlikely(!result
))
137 return ERR_PTR(-ENOMEM
);
140 * First, try to embed the struct filename inside the names_cache
143 kname
= (char *)result
->iname
;
144 result
->name
= kname
;
146 len
= strncpy_from_user(kname
, filename
, EMBEDDED_NAME_MAX
);
147 if (unlikely(len
< 0)) {
153 * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
154 * separate struct filename so we can dedicate the entire
155 * names_cache allocation for the pathname, and re-do the copy from
158 if (unlikely(len
== EMBEDDED_NAME_MAX
)) {
159 const size_t size
= offsetof(struct filename
, iname
[1]);
160 kname
= (char *)result
;
163 * size is chosen that way we to guarantee that
164 * result->iname[0] is within the same object and that
165 * kname can't be equal to result->iname, no matter what.
167 result
= kzalloc(size
, GFP_KERNEL
);
168 if (unlikely(!result
)) {
170 return ERR_PTR(-ENOMEM
);
172 result
->name
= kname
;
173 len
= strncpy_from_user(kname
, filename
, PATH_MAX
);
174 if (unlikely(len
< 0)) {
179 if (unlikely(len
== PATH_MAX
)) {
182 return ERR_PTR(-ENAMETOOLONG
);
187 /* The empty path is special. */
188 if (unlikely(!len
)) {
191 if (!(flags
& LOOKUP_EMPTY
)) {
193 return ERR_PTR(-ENOENT
);
197 result
->uptr
= filename
;
198 result
->aname
= NULL
;
199 audit_getname(result
);
204 getname(const char __user
* filename
)
206 return getname_flags(filename
, 0, NULL
);
210 getname_kernel(const char * filename
)
212 struct filename
*result
;
213 int len
= strlen(filename
) + 1;
215 result
= __getname();
216 if (unlikely(!result
))
217 return ERR_PTR(-ENOMEM
);
219 if (len
<= EMBEDDED_NAME_MAX
) {
220 result
->name
= (char *)result
->iname
;
221 } else if (len
<= PATH_MAX
) {
222 struct filename
*tmp
;
224 tmp
= kmalloc(sizeof(*tmp
), GFP_KERNEL
);
225 if (unlikely(!tmp
)) {
227 return ERR_PTR(-ENOMEM
);
229 tmp
->name
= (char *)result
;
233 return ERR_PTR(-ENAMETOOLONG
);
235 memcpy((char *)result
->name
, filename
, len
);
237 result
->aname
= NULL
;
239 audit_getname(result
);
244 void putname(struct filename
*name
)
246 BUG_ON(name
->refcnt
<= 0);
248 if (--name
->refcnt
> 0)
251 if (name
->name
!= name
->iname
) {
252 __putname(name
->name
);
258 static int check_acl(struct inode
*inode
, int mask
)
260 #ifdef CONFIG_FS_POSIX_ACL
261 struct posix_acl
*acl
;
263 if (mask
& MAY_NOT_BLOCK
) {
264 acl
= get_cached_acl_rcu(inode
, ACL_TYPE_ACCESS
);
267 /* no ->get_acl() calls in RCU mode... */
268 if (is_uncached_acl(acl
))
270 return posix_acl_permission(inode
, acl
, mask
& ~MAY_NOT_BLOCK
);
273 acl
= get_acl(inode
, ACL_TYPE_ACCESS
);
277 int error
= posix_acl_permission(inode
, acl
, mask
);
278 posix_acl_release(acl
);
287 * This does the basic permission checking
289 static int acl_permission_check(struct inode
*inode
, int mask
)
291 unsigned int mode
= inode
->i_mode
;
293 if (likely(uid_eq(current_fsuid(), inode
->i_uid
)))
296 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
)) {
297 int error
= check_acl(inode
, mask
);
298 if (error
!= -EAGAIN
)
302 if (in_group_p(inode
->i_gid
))
307 * If the DACs are ok we don't need any capability check.
309 if ((mask
& ~mode
& (MAY_READ
| MAY_WRITE
| MAY_EXEC
)) == 0)
315 * generic_permission - check for access rights on a Posix-like filesystem
316 * @inode: inode to check access rights for
317 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
319 * Used to check for read/write/execute permissions on a file.
320 * We use "fsuid" for this, letting us set arbitrary permissions
321 * for filesystem access without changing the "normal" uids which
322 * are used for other things.
324 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
325 * request cannot be satisfied (eg. requires blocking or too much complexity).
326 * It would then be called again in ref-walk mode.
328 int generic_permission(struct inode
*inode
, int mask
)
333 * Do the basic permission checks.
335 ret
= acl_permission_check(inode
, mask
);
339 if (S_ISDIR(inode
->i_mode
)) {
340 /* DACs are overridable for directories */
341 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_OVERRIDE
))
343 if (!(mask
& MAY_WRITE
))
344 if (capable_wrt_inode_uidgid(inode
,
345 CAP_DAC_READ_SEARCH
))
350 * Read/write DACs are always overridable.
351 * Executable DACs are overridable when there is
352 * at least one exec bit set.
354 if (!(mask
& MAY_EXEC
) || (inode
->i_mode
& S_IXUGO
))
355 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_OVERRIDE
))
359 * Searching includes executable on directories, else just read.
361 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
362 if (mask
== MAY_READ
)
363 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_READ_SEARCH
))
368 EXPORT_SYMBOL(generic_permission
);
371 * We _really_ want to just do "generic_permission()" without
372 * even looking at the inode->i_op values. So we keep a cache
373 * flag in inode->i_opflags, that says "this has not special
374 * permission function, use the fast case".
376 static inline int do_inode_permission(struct inode
*inode
, int mask
)
378 if (unlikely(!(inode
->i_opflags
& IOP_FASTPERM
))) {
379 if (likely(inode
->i_op
->permission
))
380 return inode
->i_op
->permission(inode
, mask
);
382 /* This gets set once for the inode lifetime */
383 spin_lock(&inode
->i_lock
);
384 inode
->i_opflags
|= IOP_FASTPERM
;
385 spin_unlock(&inode
->i_lock
);
387 return generic_permission(inode
, mask
);
391 * __inode_permission - Check for access rights to a given inode
392 * @inode: Inode to check permission on
393 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
395 * Check for read/write/execute permissions on an inode.
397 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
399 * This does not check for a read-only file system. You probably want
400 * inode_permission().
402 int __inode_permission(struct inode
*inode
, int mask
)
406 if (unlikely(mask
& MAY_WRITE
)) {
408 * Nobody gets write access to an immutable file.
410 if (IS_IMMUTABLE(inode
))
414 retval
= do_inode_permission(inode
, mask
);
418 retval
= devcgroup_inode_permission(inode
, mask
);
422 return security_inode_permission(inode
, mask
);
424 EXPORT_SYMBOL(__inode_permission
);
427 * sb_permission - Check superblock-level permissions
428 * @sb: Superblock of inode to check permission on
429 * @inode: Inode to check permission on
430 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
432 * Separate out file-system wide checks from inode-specific permission checks.
434 static int sb_permission(struct super_block
*sb
, struct inode
*inode
, int mask
)
436 if (unlikely(mask
& MAY_WRITE
)) {
437 umode_t mode
= inode
->i_mode
;
439 /* Nobody gets write access to a read-only fs. */
440 if ((sb
->s_flags
& MS_RDONLY
) &&
441 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
448 * inode_permission - Check for access rights to a given inode
449 * @inode: Inode to check permission on
450 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
452 * Check for read/write/execute permissions on an inode. We use fs[ug]id for
453 * this, letting us set arbitrary permissions for filesystem access without
454 * changing the "normal" UIDs which are used for other things.
456 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
458 int inode_permission(struct inode
*inode
, int mask
)
462 retval
= sb_permission(inode
->i_sb
, inode
, mask
);
465 return __inode_permission(inode
, mask
);
467 EXPORT_SYMBOL(inode_permission
);
470 * path_get - get a reference to a path
471 * @path: path to get the reference to
473 * Given a path increment the reference count to the dentry and the vfsmount.
475 void path_get(const struct path
*path
)
480 EXPORT_SYMBOL(path_get
);
483 * path_put - put a reference to a path
484 * @path: path to put the reference to
486 * Given a path decrement the reference count to the dentry and the vfsmount.
488 void path_put(const struct path
*path
)
493 EXPORT_SYMBOL(path_put
);
495 #define EMBEDDED_LEVELS 2
500 struct inode
*inode
; /* path.dentry.d_inode */
505 int total_link_count
;
508 struct delayed_call done
;
511 } *stack
, internal
[EMBEDDED_LEVELS
];
512 struct filename
*name
;
513 struct nameidata
*saved
;
514 struct inode
*link_inode
;
519 static void set_nameidata(struct nameidata
*p
, int dfd
, struct filename
*name
)
521 struct nameidata
*old
= current
->nameidata
;
522 p
->stack
= p
->internal
;
525 p
->total_link_count
= old
? old
->total_link_count
: 0;
527 current
->nameidata
= p
;
530 static void restore_nameidata(void)
532 struct nameidata
*now
= current
->nameidata
, *old
= now
->saved
;
534 current
->nameidata
= old
;
536 old
->total_link_count
= now
->total_link_count
;
537 if (now
->stack
!= now
->internal
)
541 static int __nd_alloc_stack(struct nameidata
*nd
)
545 if (nd
->flags
& LOOKUP_RCU
) {
546 p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
551 p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
556 memcpy(p
, nd
->internal
, sizeof(nd
->internal
));
562 * path_connected - Verify that a path->dentry is below path->mnt.mnt_root
563 * @path: nameidate to verify
565 * Rename can sometimes move a file or directory outside of a bind
566 * mount, path_connected allows those cases to be detected.
568 static bool path_connected(const struct path
*path
)
570 struct vfsmount
*mnt
= path
->mnt
;
572 /* Only bind mounts can have disconnected paths */
573 if (mnt
->mnt_root
== mnt
->mnt_sb
->s_root
)
576 return is_subdir(path
->dentry
, mnt
->mnt_root
);
579 static inline int nd_alloc_stack(struct nameidata
*nd
)
581 if (likely(nd
->depth
!= EMBEDDED_LEVELS
))
583 if (likely(nd
->stack
!= nd
->internal
))
585 return __nd_alloc_stack(nd
);
588 static void drop_links(struct nameidata
*nd
)
592 struct saved
*last
= nd
->stack
+ i
;
593 do_delayed_call(&last
->done
);
594 clear_delayed_call(&last
->done
);
598 static void terminate_walk(struct nameidata
*nd
)
601 if (!(nd
->flags
& LOOKUP_RCU
)) {
604 for (i
= 0; i
< nd
->depth
; i
++)
605 path_put(&nd
->stack
[i
].link
);
606 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
611 nd
->flags
&= ~LOOKUP_RCU
;
612 if (!(nd
->flags
& LOOKUP_ROOT
))
619 /* path_put is needed afterwards regardless of success or failure */
620 static bool legitimize_path(struct nameidata
*nd
,
621 struct path
*path
, unsigned seq
)
623 int res
= __legitimize_mnt(path
->mnt
, nd
->m_seq
);
630 if (unlikely(!lockref_get_not_dead(&path
->dentry
->d_lockref
))) {
634 return !read_seqcount_retry(&path
->dentry
->d_seq
, seq
);
637 static bool legitimize_links(struct nameidata
*nd
)
640 for (i
= 0; i
< nd
->depth
; i
++) {
641 struct saved
*last
= nd
->stack
+ i
;
642 if (unlikely(!legitimize_path(nd
, &last
->link
, last
->seq
))) {
652 * Path walking has 2 modes, rcu-walk and ref-walk (see
653 * Documentation/filesystems/path-lookup.txt). In situations when we can't
654 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
655 * normal reference counts on dentries and vfsmounts to transition to ref-walk
656 * mode. Refcounts are grabbed at the last known good point before rcu-walk
657 * got stuck, so ref-walk may continue from there. If this is not successful
658 * (eg. a seqcount has changed), then failure is returned and it's up to caller
659 * to restart the path walk from the beginning in ref-walk mode.
663 * unlazy_walk - try to switch to ref-walk mode.
664 * @nd: nameidata pathwalk data
665 * @dentry: child of nd->path.dentry or NULL
666 * @seq: seq number to check dentry against
667 * Returns: 0 on success, -ECHILD on failure
669 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
670 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
671 * @nd or NULL. Must be called from rcu-walk context.
672 * Nothing should touch nameidata between unlazy_walk() failure and
675 static int unlazy_walk(struct nameidata
*nd
, struct dentry
*dentry
, unsigned seq
)
677 struct dentry
*parent
= nd
->path
.dentry
;
679 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
681 nd
->flags
&= ~LOOKUP_RCU
;
682 if (unlikely(!legitimize_links(nd
)))
684 if (unlikely(!legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
)))
686 if (unlikely(!lockref_get_not_dead(&parent
->d_lockref
)))
690 * For a negative lookup, the lookup sequence point is the parents
691 * sequence point, and it only needs to revalidate the parent dentry.
693 * For a positive lookup, we need to move both the parent and the
694 * dentry from the RCU domain to be properly refcounted. And the
695 * sequence number in the dentry validates *both* dentry counters,
696 * since we checked the sequence number of the parent after we got
697 * the child sequence number. So we know the parent must still
698 * be valid if the child sequence number is still valid.
701 if (read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
703 BUG_ON(nd
->inode
!= parent
->d_inode
);
705 if (!lockref_get_not_dead(&dentry
->d_lockref
))
707 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
712 * Sequence counts matched. Now make sure that the root is
713 * still valid and get it if required.
715 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
716 if (unlikely(!legitimize_path(nd
, &nd
->root
, nd
->root_seq
))) {
733 nd
->path
.dentry
= NULL
;
737 if (!(nd
->flags
& LOOKUP_ROOT
))
742 static int unlazy_link(struct nameidata
*nd
, struct path
*link
, unsigned seq
)
744 if (unlikely(!legitimize_path(nd
, link
, seq
))) {
747 nd
->flags
&= ~LOOKUP_RCU
;
749 nd
->path
.dentry
= NULL
;
750 if (!(nd
->flags
& LOOKUP_ROOT
))
753 } else if (likely(unlazy_walk(nd
, NULL
, 0)) == 0) {
760 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
762 return dentry
->d_op
->d_revalidate(dentry
, flags
);
766 * complete_walk - successful completion of path walk
767 * @nd: pointer nameidata
769 * If we had been in RCU mode, drop out of it and legitimize nd->path.
770 * Revalidate the final result, unless we'd already done that during
771 * the path walk or the filesystem doesn't ask for it. Return 0 on
772 * success, -error on failure. In case of failure caller does not
773 * need to drop nd->path.
775 static int complete_walk(struct nameidata
*nd
)
777 struct dentry
*dentry
= nd
->path
.dentry
;
780 if (nd
->flags
& LOOKUP_RCU
) {
781 if (!(nd
->flags
& LOOKUP_ROOT
))
783 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
787 if (likely(!(nd
->flags
& LOOKUP_JUMPED
)))
790 if (likely(!(dentry
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)))
793 status
= dentry
->d_op
->d_weak_revalidate(dentry
, nd
->flags
);
803 static void set_root(struct nameidata
*nd
)
805 struct fs_struct
*fs
= current
->fs
;
807 if (nd
->flags
& LOOKUP_RCU
) {
811 seq
= read_seqcount_begin(&fs
->seq
);
813 nd
->root_seq
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
814 } while (read_seqcount_retry(&fs
->seq
, seq
));
816 get_fs_root(fs
, &nd
->root
);
820 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
823 if (path
->mnt
!= nd
->path
.mnt
)
827 static inline void path_to_nameidata(const struct path
*path
,
828 struct nameidata
*nd
)
830 if (!(nd
->flags
& LOOKUP_RCU
)) {
831 dput(nd
->path
.dentry
);
832 if (nd
->path
.mnt
!= path
->mnt
)
833 mntput(nd
->path
.mnt
);
835 nd
->path
.mnt
= path
->mnt
;
836 nd
->path
.dentry
= path
->dentry
;
839 static int nd_jump_root(struct nameidata
*nd
)
841 if (nd
->flags
& LOOKUP_RCU
) {
845 nd
->inode
= d
->d_inode
;
846 nd
->seq
= nd
->root_seq
;
847 if (unlikely(read_seqcount_retry(&d
->d_seq
, nd
->seq
)))
853 nd
->inode
= nd
->path
.dentry
->d_inode
;
855 nd
->flags
|= LOOKUP_JUMPED
;
860 * Helper to directly jump to a known parsed path from ->get_link,
861 * caller must have taken a reference to path beforehand.
863 void nd_jump_link(struct path
*path
)
865 struct nameidata
*nd
= current
->nameidata
;
869 nd
->inode
= nd
->path
.dentry
->d_inode
;
870 nd
->flags
|= LOOKUP_JUMPED
;
873 static inline void put_link(struct nameidata
*nd
)
875 struct saved
*last
= nd
->stack
+ --nd
->depth
;
876 do_delayed_call(&last
->done
);
877 if (!(nd
->flags
& LOOKUP_RCU
))
878 path_put(&last
->link
);
881 int sysctl_protected_symlinks __read_mostly
= 0;
882 int sysctl_protected_hardlinks __read_mostly
= 0;
885 * may_follow_link - Check symlink following for unsafe situations
886 * @nd: nameidata pathwalk data
888 * In the case of the sysctl_protected_symlinks sysctl being enabled,
889 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
890 * in a sticky world-writable directory. This is to protect privileged
891 * processes from failing races against path names that may change out
892 * from under them by way of other users creating malicious symlinks.
893 * It will permit symlinks to be followed only when outside a sticky
894 * world-writable directory, or when the uid of the symlink and follower
895 * match, or when the directory owner matches the symlink's owner.
897 * Returns 0 if following the symlink is allowed, -ve on error.
899 static inline int may_follow_link(struct nameidata
*nd
)
901 const struct inode
*inode
;
902 const struct inode
*parent
;
904 if (!sysctl_protected_symlinks
)
907 /* Allowed if owner and follower match. */
908 inode
= nd
->link_inode
;
909 if (uid_eq(current_cred()->fsuid
, inode
->i_uid
))
912 /* Allowed if parent directory not sticky and world-writable. */
914 if ((parent
->i_mode
& (S_ISVTX
|S_IWOTH
)) != (S_ISVTX
|S_IWOTH
))
917 /* Allowed if parent directory and link owner match. */
918 if (uid_eq(parent
->i_uid
, inode
->i_uid
))
921 if (nd
->flags
& LOOKUP_RCU
)
924 audit_log_link_denied("follow_link", &nd
->stack
[0].link
);
929 * safe_hardlink_source - Check for safe hardlink conditions
930 * @inode: the source inode to hardlink from
932 * Return false if at least one of the following conditions:
933 * - inode is not a regular file
935 * - inode is setgid and group-exec
936 * - access failure for read and write
938 * Otherwise returns true.
940 static bool safe_hardlink_source(struct inode
*inode
)
942 umode_t mode
= inode
->i_mode
;
944 /* Special files should not get pinned to the filesystem. */
948 /* Setuid files should not get pinned to the filesystem. */
952 /* Executable setgid files should not get pinned to the filesystem. */
953 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
))
956 /* Hardlinking to unreadable or unwritable sources is dangerous. */
957 if (inode_permission(inode
, MAY_READ
| MAY_WRITE
))
964 * may_linkat - Check permissions for creating a hardlink
965 * @link: the source to hardlink from
967 * Block hardlink when all of:
968 * - sysctl_protected_hardlinks enabled
969 * - fsuid does not match inode
970 * - hardlink source is unsafe (see safe_hardlink_source() above)
971 * - not CAP_FOWNER in a namespace with the inode owner uid mapped
973 * Returns 0 if successful, -ve on error.
975 static int may_linkat(struct path
*link
)
979 if (!sysctl_protected_hardlinks
)
982 inode
= link
->dentry
->d_inode
;
984 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
985 * otherwise, it must be a safe source.
987 if (inode_owner_or_capable(inode
) || safe_hardlink_source(inode
))
990 audit_log_link_denied("linkat", link
);
994 static __always_inline
995 const char *get_link(struct nameidata
*nd
)
997 struct saved
*last
= nd
->stack
+ nd
->depth
- 1;
998 struct dentry
*dentry
= last
->link
.dentry
;
999 struct inode
*inode
= nd
->link_inode
;
1003 if (!(nd
->flags
& LOOKUP_RCU
)) {
1004 touch_atime(&last
->link
);
1006 } else if (atime_needs_update(&last
->link
, inode
)) {
1007 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
1008 return ERR_PTR(-ECHILD
);
1009 touch_atime(&last
->link
);
1012 error
= security_inode_follow_link(dentry
, inode
,
1013 nd
->flags
& LOOKUP_RCU
);
1014 if (unlikely(error
))
1015 return ERR_PTR(error
);
1017 nd
->last_type
= LAST_BIND
;
1018 res
= inode
->i_link
;
1020 const char * (*get
)(struct dentry
*, struct inode
*,
1021 struct delayed_call
*);
1022 get
= inode
->i_op
->get_link
;
1023 if (nd
->flags
& LOOKUP_RCU
) {
1024 res
= get(NULL
, inode
, &last
->done
);
1025 if (res
== ERR_PTR(-ECHILD
)) {
1026 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
1027 return ERR_PTR(-ECHILD
);
1028 res
= get(dentry
, inode
, &last
->done
);
1031 res
= get(dentry
, inode
, &last
->done
);
1033 if (IS_ERR_OR_NULL(res
))
1039 if (unlikely(nd_jump_root(nd
)))
1040 return ERR_PTR(-ECHILD
);
1041 while (unlikely(*++res
== '/'))
1050 * follow_up - Find the mountpoint of path's vfsmount
1052 * Given a path, find the mountpoint of its source file system.
1053 * Replace @path with the path of the mountpoint in the parent mount.
1056 * Return 1 if we went up a level and 0 if we were already at the
1059 int follow_up(struct path
*path
)
1061 struct mount
*mnt
= real_mount(path
->mnt
);
1062 struct mount
*parent
;
1063 struct dentry
*mountpoint
;
1065 read_seqlock_excl(&mount_lock
);
1066 parent
= mnt
->mnt_parent
;
1067 if (parent
== mnt
) {
1068 read_sequnlock_excl(&mount_lock
);
1071 mntget(&parent
->mnt
);
1072 mountpoint
= dget(mnt
->mnt_mountpoint
);
1073 read_sequnlock_excl(&mount_lock
);
1075 path
->dentry
= mountpoint
;
1077 path
->mnt
= &parent
->mnt
;
1080 EXPORT_SYMBOL(follow_up
);
1083 * Perform an automount
1084 * - return -EISDIR to tell follow_managed() to stop and return the path we
1087 static int follow_automount(struct path
*path
, struct nameidata
*nd
,
1090 struct vfsmount
*mnt
;
1093 if (!path
->dentry
->d_op
|| !path
->dentry
->d_op
->d_automount
)
1096 /* We don't want to mount if someone's just doing a stat -
1097 * unless they're stat'ing a directory and appended a '/' to
1100 * We do, however, want to mount if someone wants to open or
1101 * create a file of any type under the mountpoint, wants to
1102 * traverse through the mountpoint or wants to open the
1103 * mounted directory. Also, autofs may mark negative dentries
1104 * as being automount points. These will need the attentions
1105 * of the daemon to instantiate them before they can be used.
1107 if (!(nd
->flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
1108 LOOKUP_OPEN
| LOOKUP_CREATE
| LOOKUP_AUTOMOUNT
)) &&
1109 path
->dentry
->d_inode
)
1112 nd
->total_link_count
++;
1113 if (nd
->total_link_count
>= 40)
1116 mnt
= path
->dentry
->d_op
->d_automount(path
);
1119 * The filesystem is allowed to return -EISDIR here to indicate
1120 * it doesn't want to automount. For instance, autofs would do
1121 * this so that its userspace daemon can mount on this dentry.
1123 * However, we can only permit this if it's a terminal point in
1124 * the path being looked up; if it wasn't then the remainder of
1125 * the path is inaccessible and we should say so.
1127 if (PTR_ERR(mnt
) == -EISDIR
&& (nd
->flags
& LOOKUP_PARENT
))
1129 return PTR_ERR(mnt
);
1132 if (!mnt
) /* mount collision */
1135 if (!*need_mntput
) {
1136 /* lock_mount() may release path->mnt on error */
1138 *need_mntput
= true;
1140 err
= finish_automount(mnt
, path
);
1144 /* Someone else made a mount here whilst we were busy */
1149 path
->dentry
= dget(mnt
->mnt_root
);
1158 * Handle a dentry that is managed in some way.
1159 * - Flagged for transit management (autofs)
1160 * - Flagged as mountpoint
1161 * - Flagged as automount point
1163 * This may only be called in refwalk mode.
1165 * Serialization is taken care of in namespace.c
1167 static int follow_managed(struct path
*path
, struct nameidata
*nd
)
1169 struct vfsmount
*mnt
= path
->mnt
; /* held by caller, must be left alone */
1171 bool need_mntput
= false;
1174 /* Given that we're not holding a lock here, we retain the value in a
1175 * local variable for each dentry as we look at it so that we don't see
1176 * the components of that value change under us */
1177 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1178 managed
&= DCACHE_MANAGED_DENTRY
,
1179 unlikely(managed
!= 0)) {
1180 /* Allow the filesystem to manage the transit without i_mutex
1182 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1183 BUG_ON(!path
->dentry
->d_op
);
1184 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1185 ret
= path
->dentry
->d_op
->d_manage(path
->dentry
, false);
1190 /* Transit to a mounted filesystem. */
1191 if (managed
& DCACHE_MOUNTED
) {
1192 struct vfsmount
*mounted
= lookup_mnt(path
);
1197 path
->mnt
= mounted
;
1198 path
->dentry
= dget(mounted
->mnt_root
);
1203 /* Something is mounted on this dentry in another
1204 * namespace and/or whatever was mounted there in this
1205 * namespace got unmounted before lookup_mnt() could
1209 /* Handle an automount point */
1210 if (managed
& DCACHE_NEED_AUTOMOUNT
) {
1211 ret
= follow_automount(path
, nd
, &need_mntput
);
1217 /* We didn't change the current path point */
1221 if (need_mntput
&& path
->mnt
== mnt
)
1223 if (ret
== -EISDIR
|| !ret
)
1226 nd
->flags
|= LOOKUP_JUMPED
;
1227 if (unlikely(ret
< 0))
1228 path_put_conditional(path
, nd
);
1232 int follow_down_one(struct path
*path
)
1234 struct vfsmount
*mounted
;
1236 mounted
= lookup_mnt(path
);
1240 path
->mnt
= mounted
;
1241 path
->dentry
= dget(mounted
->mnt_root
);
1246 EXPORT_SYMBOL(follow_down_one
);
1248 static inline int managed_dentry_rcu(struct dentry
*dentry
)
1250 return (dentry
->d_flags
& DCACHE_MANAGE_TRANSIT
) ?
1251 dentry
->d_op
->d_manage(dentry
, true) : 0;
1255 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1256 * we meet a managed dentry that would need blocking.
1258 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
,
1259 struct inode
**inode
, unsigned *seqp
)
1262 struct mount
*mounted
;
1264 * Don't forget we might have a non-mountpoint managed dentry
1265 * that wants to block transit.
1267 switch (managed_dentry_rcu(path
->dentry
)) {
1277 if (!d_mountpoint(path
->dentry
))
1278 return !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1280 mounted
= __lookup_mnt(path
->mnt
, path
->dentry
);
1283 path
->mnt
= &mounted
->mnt
;
1284 path
->dentry
= mounted
->mnt
.mnt_root
;
1285 nd
->flags
|= LOOKUP_JUMPED
;
1286 *seqp
= read_seqcount_begin(&path
->dentry
->d_seq
);
1288 * Update the inode too. We don't need to re-check the
1289 * dentry sequence number here after this d_inode read,
1290 * because a mount-point is always pinned.
1292 *inode
= path
->dentry
->d_inode
;
1294 return !read_seqretry(&mount_lock
, nd
->m_seq
) &&
1295 !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1298 static int follow_dotdot_rcu(struct nameidata
*nd
)
1300 struct inode
*inode
= nd
->inode
;
1303 if (path_equal(&nd
->path
, &nd
->root
))
1305 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1306 struct dentry
*old
= nd
->path
.dentry
;
1307 struct dentry
*parent
= old
->d_parent
;
1310 inode
= parent
->d_inode
;
1311 seq
= read_seqcount_begin(&parent
->d_seq
);
1312 if (unlikely(read_seqcount_retry(&old
->d_seq
, nd
->seq
)))
1314 nd
->path
.dentry
= parent
;
1316 if (unlikely(!path_connected(&nd
->path
)))
1320 struct mount
*mnt
= real_mount(nd
->path
.mnt
);
1321 struct mount
*mparent
= mnt
->mnt_parent
;
1322 struct dentry
*mountpoint
= mnt
->mnt_mountpoint
;
1323 struct inode
*inode2
= mountpoint
->d_inode
;
1324 unsigned seq
= read_seqcount_begin(&mountpoint
->d_seq
);
1325 if (unlikely(read_seqretry(&mount_lock
, nd
->m_seq
)))
1327 if (&mparent
->mnt
== nd
->path
.mnt
)
1329 /* we know that mountpoint was pinned */
1330 nd
->path
.dentry
= mountpoint
;
1331 nd
->path
.mnt
= &mparent
->mnt
;
1336 while (unlikely(d_mountpoint(nd
->path
.dentry
))) {
1337 struct mount
*mounted
;
1338 mounted
= __lookup_mnt(nd
->path
.mnt
, nd
->path
.dentry
);
1339 if (unlikely(read_seqretry(&mount_lock
, nd
->m_seq
)))
1343 nd
->path
.mnt
= &mounted
->mnt
;
1344 nd
->path
.dentry
= mounted
->mnt
.mnt_root
;
1345 inode
= nd
->path
.dentry
->d_inode
;
1346 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1353 * Follow down to the covering mount currently visible to userspace. At each
1354 * point, the filesystem owning that dentry may be queried as to whether the
1355 * caller is permitted to proceed or not.
1357 int follow_down(struct path
*path
)
1362 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1363 unlikely(managed
& DCACHE_MANAGED_DENTRY
)) {
1364 /* Allow the filesystem to manage the transit without i_mutex
1367 * We indicate to the filesystem if someone is trying to mount
1368 * something here. This gives autofs the chance to deny anyone
1369 * other than its daemon the right to mount on its
1372 * The filesystem may sleep at this point.
1374 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1375 BUG_ON(!path
->dentry
->d_op
);
1376 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1377 ret
= path
->dentry
->d_op
->d_manage(
1378 path
->dentry
, false);
1380 return ret
== -EISDIR
? 0 : ret
;
1383 /* Transit to a mounted filesystem. */
1384 if (managed
& DCACHE_MOUNTED
) {
1385 struct vfsmount
*mounted
= lookup_mnt(path
);
1390 path
->mnt
= mounted
;
1391 path
->dentry
= dget(mounted
->mnt_root
);
1395 /* Don't handle automount points here */
1400 EXPORT_SYMBOL(follow_down
);
1403 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1405 static void follow_mount(struct path
*path
)
1407 while (d_mountpoint(path
->dentry
)) {
1408 struct vfsmount
*mounted
= lookup_mnt(path
);
1413 path
->mnt
= mounted
;
1414 path
->dentry
= dget(mounted
->mnt_root
);
1418 static int follow_dotdot(struct nameidata
*nd
)
1421 struct dentry
*old
= nd
->path
.dentry
;
1423 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1424 nd
->path
.mnt
== nd
->root
.mnt
) {
1427 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1428 /* rare case of legitimate dget_parent()... */
1429 nd
->path
.dentry
= dget_parent(nd
->path
.dentry
);
1431 if (unlikely(!path_connected(&nd
->path
)))
1435 if (!follow_up(&nd
->path
))
1438 follow_mount(&nd
->path
);
1439 nd
->inode
= nd
->path
.dentry
->d_inode
;
1444 * This looks up the name in dcache, possibly revalidates the old dentry and
1445 * allocates a new one if not found or not valid. In the need_lookup argument
1446 * returns whether i_op->lookup is necessary.
1448 static struct dentry
*lookup_dcache(const struct qstr
*name
,
1452 struct dentry
*dentry
;
1455 dentry
= d_lookup(dir
, name
);
1457 if (dentry
->d_flags
& DCACHE_OP_REVALIDATE
) {
1458 error
= d_revalidate(dentry
, flags
);
1459 if (unlikely(error
<= 0)) {
1461 d_invalidate(dentry
);
1463 return ERR_PTR(error
);
1471 * Call i_op->lookup on the dentry. The dentry must be negative and
1474 * dir->d_inode->i_mutex must be held
1476 static struct dentry
*lookup_real(struct inode
*dir
, struct dentry
*dentry
,
1481 /* Don't create child dentry for a dead directory. */
1482 if (unlikely(IS_DEADDIR(dir
))) {
1484 return ERR_PTR(-ENOENT
);
1487 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1488 if (unlikely(old
)) {
1495 static struct dentry
*__lookup_hash(const struct qstr
*name
,
1496 struct dentry
*base
, unsigned int flags
)
1498 struct dentry
*dentry
= lookup_dcache(name
, base
, flags
);
1503 dentry
= d_alloc(base
, name
);
1504 if (unlikely(!dentry
))
1505 return ERR_PTR(-ENOMEM
);
1507 return lookup_real(base
->d_inode
, dentry
, flags
);
1510 static int lookup_fast(struct nameidata
*nd
,
1511 struct path
*path
, struct inode
**inode
,
1514 struct vfsmount
*mnt
= nd
->path
.mnt
;
1515 struct dentry
*dentry
, *parent
= nd
->path
.dentry
;
1520 * Rename seqlock is not required here because in the off chance
1521 * of a false negative due to a concurrent rename, the caller is
1522 * going to fall back to non-racy lookup.
1524 if (nd
->flags
& LOOKUP_RCU
) {
1527 dentry
= __d_lookup_rcu(parent
, &nd
->last
, &seq
);
1528 if (unlikely(!dentry
)) {
1529 if (unlazy_walk(nd
, NULL
, 0))
1535 * This sequence count validates that the inode matches
1536 * the dentry name information from lookup.
1538 *inode
= d_backing_inode(dentry
);
1539 negative
= d_is_negative(dentry
);
1540 if (unlikely(read_seqcount_retry(&dentry
->d_seq
, seq
)))
1544 * This sequence count validates that the parent had no
1545 * changes while we did the lookup of the dentry above.
1547 * The memory barrier in read_seqcount_begin of child is
1548 * enough, we can use __read_seqcount_retry here.
1550 if (unlikely(__read_seqcount_retry(&parent
->d_seq
, nd
->seq
)))
1554 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
))
1555 status
= d_revalidate(dentry
, nd
->flags
);
1556 if (unlikely(status
<= 0)) {
1557 if (unlazy_walk(nd
, dentry
, seq
))
1559 if (status
== -ECHILD
)
1560 status
= d_revalidate(dentry
, nd
->flags
);
1563 * Note: do negative dentry check after revalidation in
1564 * case that drops it.
1566 if (unlikely(negative
))
1569 path
->dentry
= dentry
;
1570 if (likely(__follow_mount_rcu(nd
, path
, inode
, seqp
)))
1572 if (unlazy_walk(nd
, dentry
, seq
))
1576 dentry
= __d_lookup(parent
, &nd
->last
);
1577 if (unlikely(!dentry
))
1579 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
))
1580 status
= d_revalidate(dentry
, nd
->flags
);
1582 if (unlikely(status
<= 0)) {
1584 d_invalidate(dentry
);
1588 if (unlikely(d_is_negative(dentry
))) {
1594 path
->dentry
= dentry
;
1595 err
= follow_managed(path
, nd
);
1596 if (likely(err
> 0))
1597 *inode
= d_backing_inode(path
->dentry
);
1601 /* Fast lookup failed, do it the slow way */
1602 static struct dentry
*lookup_slow(const struct qstr
*name
,
1606 struct dentry
*dentry
;
1607 inode_lock(dir
->d_inode
);
1608 dentry
= d_lookup(dir
, name
);
1609 if (unlikely(dentry
)) {
1610 if ((dentry
->d_flags
& DCACHE_OP_REVALIDATE
) &&
1611 !(flags
& LOOKUP_NO_REVAL
)) {
1612 int error
= d_revalidate(dentry
, flags
);
1613 if (unlikely(error
<= 0)) {
1615 d_invalidate(dentry
);
1617 dentry
= ERR_PTR(error
);
1621 inode_unlock(dir
->d_inode
);
1625 dentry
= d_alloc(dir
, name
);
1626 if (unlikely(!dentry
)) {
1627 inode_unlock(dir
->d_inode
);
1628 return ERR_PTR(-ENOMEM
);
1630 dentry
= lookup_real(dir
->d_inode
, dentry
, flags
);
1631 inode_unlock(dir
->d_inode
);
1635 static inline int may_lookup(struct nameidata
*nd
)
1637 if (nd
->flags
& LOOKUP_RCU
) {
1638 int err
= inode_permission(nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1641 if (unlazy_walk(nd
, NULL
, 0))
1644 return inode_permission(nd
->inode
, MAY_EXEC
);
1647 static inline int handle_dots(struct nameidata
*nd
, int type
)
1649 if (type
== LAST_DOTDOT
) {
1652 if (nd
->flags
& LOOKUP_RCU
) {
1653 return follow_dotdot_rcu(nd
);
1655 return follow_dotdot(nd
);
1660 static int pick_link(struct nameidata
*nd
, struct path
*link
,
1661 struct inode
*inode
, unsigned seq
)
1665 if (unlikely(nd
->total_link_count
++ >= MAXSYMLINKS
)) {
1666 path_to_nameidata(link
, nd
);
1669 if (!(nd
->flags
& LOOKUP_RCU
)) {
1670 if (link
->mnt
== nd
->path
.mnt
)
1673 error
= nd_alloc_stack(nd
);
1674 if (unlikely(error
)) {
1675 if (error
== -ECHILD
) {
1676 if (unlikely(unlazy_link(nd
, link
, seq
)))
1678 error
= nd_alloc_stack(nd
);
1686 last
= nd
->stack
+ nd
->depth
++;
1688 clear_delayed_call(&last
->done
);
1689 nd
->link_inode
= inode
;
1695 * Do we need to follow links? We _really_ want to be able
1696 * to do this check without having to look at inode->i_op,
1697 * so we keep a cache of "no, this doesn't need follow_link"
1698 * for the common case.
1700 static inline int should_follow_link(struct nameidata
*nd
, struct path
*link
,
1702 struct inode
*inode
, unsigned seq
)
1704 if (likely(!d_is_symlink(link
->dentry
)))
1708 /* make sure that d_is_symlink above matches inode */
1709 if (nd
->flags
& LOOKUP_RCU
) {
1710 if (read_seqcount_retry(&link
->dentry
->d_seq
, seq
))
1713 return pick_link(nd
, link
, inode
, seq
);
1716 enum {WALK_GET
= 1, WALK_PUT
= 2};
1718 static int walk_component(struct nameidata
*nd
, int flags
)
1721 struct inode
*inode
;
1725 * "." and ".." are special - ".." especially so because it has
1726 * to be able to know about the current root directory and
1727 * parent relationships.
1729 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
1730 err
= handle_dots(nd
, nd
->last_type
);
1731 if (flags
& WALK_PUT
)
1735 err
= lookup_fast(nd
, &path
, &inode
, &seq
);
1736 if (unlikely(err
<= 0)) {
1739 path
.dentry
= lookup_slow(&nd
->last
, nd
->path
.dentry
,
1741 if (IS_ERR(path
.dentry
))
1742 return PTR_ERR(path
.dentry
);
1743 if (unlikely(d_is_negative(path
.dentry
))) {
1747 path
.mnt
= nd
->path
.mnt
;
1748 err
= follow_managed(&path
, nd
);
1749 if (unlikely(err
< 0))
1752 seq
= 0; /* we are already out of RCU mode */
1753 inode
= d_backing_inode(path
.dentry
);
1756 if (flags
& WALK_PUT
)
1758 err
= should_follow_link(nd
, &path
, flags
& WALK_GET
, inode
, seq
);
1761 path_to_nameidata(&path
, nd
);
1768 * We can do the critical dentry name comparison and hashing
1769 * operations one word at a time, but we are limited to:
1771 * - Architectures with fast unaligned word accesses. We could
1772 * do a "get_unaligned()" if this helps and is sufficiently
1775 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1776 * do not trap on the (extremely unlikely) case of a page
1777 * crossing operation.
1779 * - Furthermore, we need an efficient 64-bit compile for the
1780 * 64-bit case in order to generate the "number of bytes in
1781 * the final mask". Again, that could be replaced with a
1782 * efficient population count instruction or similar.
1784 #ifdef CONFIG_DCACHE_WORD_ACCESS
1786 #include <asm/word-at-a-time.h>
1790 static inline unsigned int fold_hash(unsigned long hash
)
1792 return hash_64(hash
, 32);
1795 #else /* 32-bit case */
1797 #define fold_hash(x) (x)
1801 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1803 unsigned long a
, mask
;
1804 unsigned long hash
= 0;
1807 a
= load_unaligned_zeropad(name
);
1808 if (len
< sizeof(unsigned long))
1812 name
+= sizeof(unsigned long);
1813 len
-= sizeof(unsigned long);
1817 mask
= bytemask_from_count(len
);
1820 return fold_hash(hash
);
1822 EXPORT_SYMBOL(full_name_hash
);
1825 * Calculate the length and hash of the path component, and
1826 * return the "hash_len" as the result.
1828 static inline u64
hash_name(const char *name
)
1830 unsigned long a
, b
, adata
, bdata
, mask
, hash
, len
;
1831 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
1834 len
= -sizeof(unsigned long);
1836 hash
= (hash
+ a
) * 9;
1837 len
+= sizeof(unsigned long);
1838 a
= load_unaligned_zeropad(name
+len
);
1839 b
= a
^ REPEAT_BYTE('/');
1840 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
1842 adata
= prep_zero_mask(a
, adata
, &constants
);
1843 bdata
= prep_zero_mask(b
, bdata
, &constants
);
1845 mask
= create_zero_mask(adata
| bdata
);
1847 hash
+= a
& zero_bytemask(mask
);
1848 len
+= find_zero(mask
);
1849 return hashlen_create(fold_hash(hash
), len
);
1854 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1856 unsigned long hash
= init_name_hash();
1858 hash
= partial_name_hash(*name
++, hash
);
1859 return end_name_hash(hash
);
1861 EXPORT_SYMBOL(full_name_hash
);
1864 * We know there's a real path component here of at least
1867 static inline u64
hash_name(const char *name
)
1869 unsigned long hash
= init_name_hash();
1870 unsigned long len
= 0, c
;
1872 c
= (unsigned char)*name
;
1875 hash
= partial_name_hash(c
, hash
);
1876 c
= (unsigned char)name
[len
];
1877 } while (c
&& c
!= '/');
1878 return hashlen_create(end_name_hash(hash
), len
);
1885 * This is the basic name resolution function, turning a pathname into
1886 * the final dentry. We expect 'base' to be positive and a directory.
1888 * Returns 0 and nd will have valid dentry and mnt on success.
1889 * Returns error and drops reference to input namei data on failure.
1891 static int link_path_walk(const char *name
, struct nameidata
*nd
)
1900 /* At this point we know we have a real path component. */
1905 err
= may_lookup(nd
);
1909 hash_len
= hash_name(name
);
1912 if (name
[0] == '.') switch (hashlen_len(hash_len
)) {
1914 if (name
[1] == '.') {
1916 nd
->flags
|= LOOKUP_JUMPED
;
1922 if (likely(type
== LAST_NORM
)) {
1923 struct dentry
*parent
= nd
->path
.dentry
;
1924 nd
->flags
&= ~LOOKUP_JUMPED
;
1925 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
1926 struct qstr
this = { { .hash_len
= hash_len
}, .name
= name
};
1927 err
= parent
->d_op
->d_hash(parent
, &this);
1930 hash_len
= this.hash_len
;
1935 nd
->last
.hash_len
= hash_len
;
1936 nd
->last
.name
= name
;
1937 nd
->last_type
= type
;
1939 name
+= hashlen_len(hash_len
);
1943 * If it wasn't NUL, we know it was '/'. Skip that
1944 * slash, and continue until no more slashes.
1948 } while (unlikely(*name
== '/'));
1949 if (unlikely(!*name
)) {
1951 /* pathname body, done */
1954 name
= nd
->stack
[nd
->depth
- 1].name
;
1955 /* trailing symlink, done */
1958 /* last component of nested symlink */
1959 err
= walk_component(nd
, WALK_GET
| WALK_PUT
);
1961 err
= walk_component(nd
, WALK_GET
);
1967 const char *s
= get_link(nd
);
1976 nd
->stack
[nd
->depth
- 1].name
= name
;
1981 if (unlikely(!d_can_lookup(nd
->path
.dentry
))) {
1982 if (nd
->flags
& LOOKUP_RCU
) {
1983 if (unlazy_walk(nd
, NULL
, 0))
1991 static const char *path_init(struct nameidata
*nd
, unsigned flags
)
1994 const char *s
= nd
->name
->name
;
1996 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1997 nd
->flags
= flags
| LOOKUP_JUMPED
| LOOKUP_PARENT
;
1999 if (flags
& LOOKUP_ROOT
) {
2000 struct dentry
*root
= nd
->root
.dentry
;
2001 struct inode
*inode
= root
->d_inode
;
2003 if (!d_can_lookup(root
))
2004 return ERR_PTR(-ENOTDIR
);
2005 retval
= inode_permission(inode
, MAY_EXEC
);
2007 return ERR_PTR(retval
);
2009 nd
->path
= nd
->root
;
2011 if (flags
& LOOKUP_RCU
) {
2013 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2014 nd
->root_seq
= nd
->seq
;
2015 nd
->m_seq
= read_seqbegin(&mount_lock
);
2017 path_get(&nd
->path
);
2022 nd
->root
.mnt
= NULL
;
2023 nd
->path
.mnt
= NULL
;
2024 nd
->path
.dentry
= NULL
;
2026 nd
->m_seq
= read_seqbegin(&mount_lock
);
2028 if (flags
& LOOKUP_RCU
)
2031 if (likely(!nd_jump_root(nd
)))
2033 nd
->root
.mnt
= NULL
;
2035 return ERR_PTR(-ECHILD
);
2036 } else if (nd
->dfd
== AT_FDCWD
) {
2037 if (flags
& LOOKUP_RCU
) {
2038 struct fs_struct
*fs
= current
->fs
;
2044 seq
= read_seqcount_begin(&fs
->seq
);
2046 nd
->inode
= nd
->path
.dentry
->d_inode
;
2047 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2048 } while (read_seqcount_retry(&fs
->seq
, seq
));
2050 get_fs_pwd(current
->fs
, &nd
->path
);
2051 nd
->inode
= nd
->path
.dentry
->d_inode
;
2055 /* Caller must check execute permissions on the starting path component */
2056 struct fd f
= fdget_raw(nd
->dfd
);
2057 struct dentry
*dentry
;
2060 return ERR_PTR(-EBADF
);
2062 dentry
= f
.file
->f_path
.dentry
;
2065 if (!d_can_lookup(dentry
)) {
2067 return ERR_PTR(-ENOTDIR
);
2071 nd
->path
= f
.file
->f_path
;
2072 if (flags
& LOOKUP_RCU
) {
2074 nd
->inode
= nd
->path
.dentry
->d_inode
;
2075 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2077 path_get(&nd
->path
);
2078 nd
->inode
= nd
->path
.dentry
->d_inode
;
2085 static const char *trailing_symlink(struct nameidata
*nd
)
2088 int error
= may_follow_link(nd
);
2089 if (unlikely(error
))
2090 return ERR_PTR(error
);
2091 nd
->flags
|= LOOKUP_PARENT
;
2092 nd
->stack
[0].name
= NULL
;
2097 static inline int lookup_last(struct nameidata
*nd
)
2099 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
2100 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2102 nd
->flags
&= ~LOOKUP_PARENT
;
2103 return walk_component(nd
,
2104 nd
->flags
& LOOKUP_FOLLOW
2106 ? WALK_PUT
| WALK_GET
2111 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2112 static int path_lookupat(struct nameidata
*nd
, unsigned flags
, struct path
*path
)
2114 const char *s
= path_init(nd
, flags
);
2119 while (!(err
= link_path_walk(s
, nd
))
2120 && ((err
= lookup_last(nd
)) > 0)) {
2121 s
= trailing_symlink(nd
);
2128 err
= complete_walk(nd
);
2130 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
)
2131 if (!d_can_lookup(nd
->path
.dentry
))
2135 nd
->path
.mnt
= NULL
;
2136 nd
->path
.dentry
= NULL
;
2142 static int filename_lookup(int dfd
, struct filename
*name
, unsigned flags
,
2143 struct path
*path
, struct path
*root
)
2146 struct nameidata nd
;
2148 return PTR_ERR(name
);
2149 if (unlikely(root
)) {
2151 flags
|= LOOKUP_ROOT
;
2153 set_nameidata(&nd
, dfd
, name
);
2154 retval
= path_lookupat(&nd
, flags
| LOOKUP_RCU
, path
);
2155 if (unlikely(retval
== -ECHILD
))
2156 retval
= path_lookupat(&nd
, flags
, path
);
2157 if (unlikely(retval
== -ESTALE
))
2158 retval
= path_lookupat(&nd
, flags
| LOOKUP_REVAL
, path
);
2160 if (likely(!retval
))
2161 audit_inode(name
, path
->dentry
, flags
& LOOKUP_PARENT
);
2162 restore_nameidata();
2167 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2168 static int path_parentat(struct nameidata
*nd
, unsigned flags
,
2169 struct path
*parent
)
2171 const char *s
= path_init(nd
, flags
);
2175 err
= link_path_walk(s
, nd
);
2177 err
= complete_walk(nd
);
2180 nd
->path
.mnt
= NULL
;
2181 nd
->path
.dentry
= NULL
;
2187 static struct filename
*filename_parentat(int dfd
, struct filename
*name
,
2188 unsigned int flags
, struct path
*parent
,
2189 struct qstr
*last
, int *type
)
2192 struct nameidata nd
;
2196 set_nameidata(&nd
, dfd
, name
);
2197 retval
= path_parentat(&nd
, flags
| LOOKUP_RCU
, parent
);
2198 if (unlikely(retval
== -ECHILD
))
2199 retval
= path_parentat(&nd
, flags
, parent
);
2200 if (unlikely(retval
== -ESTALE
))
2201 retval
= path_parentat(&nd
, flags
| LOOKUP_REVAL
, parent
);
2202 if (likely(!retval
)) {
2204 *type
= nd
.last_type
;
2205 audit_inode(name
, parent
->dentry
, LOOKUP_PARENT
);
2208 name
= ERR_PTR(retval
);
2210 restore_nameidata();
2214 /* does lookup, returns the object with parent locked */
2215 struct dentry
*kern_path_locked(const char *name
, struct path
*path
)
2217 struct filename
*filename
;
2222 filename
= filename_parentat(AT_FDCWD
, getname_kernel(name
), 0, path
,
2224 if (IS_ERR(filename
))
2225 return ERR_CAST(filename
);
2226 if (unlikely(type
!= LAST_NORM
)) {
2229 return ERR_PTR(-EINVAL
);
2231 inode_lock_nested(path
->dentry
->d_inode
, I_MUTEX_PARENT
);
2232 d
= __lookup_hash(&last
, path
->dentry
, 0);
2234 inode_unlock(path
->dentry
->d_inode
);
2241 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
2243 return filename_lookup(AT_FDCWD
, getname_kernel(name
),
2246 EXPORT_SYMBOL(kern_path
);
2249 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2250 * @dentry: pointer to dentry of the base directory
2251 * @mnt: pointer to vfs mount of the base directory
2252 * @name: pointer to file name
2253 * @flags: lookup flags
2254 * @path: pointer to struct path to fill
2256 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
2257 const char *name
, unsigned int flags
,
2260 struct path root
= {.mnt
= mnt
, .dentry
= dentry
};
2261 /* the first argument of filename_lookup() is ignored with root */
2262 return filename_lookup(AT_FDCWD
, getname_kernel(name
),
2263 flags
, path
, &root
);
2265 EXPORT_SYMBOL(vfs_path_lookup
);
2268 * lookup_one_len - filesystem helper to lookup single pathname component
2269 * @name: pathname component to lookup
2270 * @base: base directory to lookup from
2271 * @len: maximum length @len should be interpreted to
2273 * Note that this routine is purely a helper for filesystem usage and should
2274 * not be called by generic code.
2276 * The caller must hold base->i_mutex.
2278 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2284 WARN_ON_ONCE(!inode_is_locked(base
->d_inode
));
2288 this.hash
= full_name_hash(name
, len
);
2290 return ERR_PTR(-EACCES
);
2292 if (unlikely(name
[0] == '.')) {
2293 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2294 return ERR_PTR(-EACCES
);
2298 c
= *(const unsigned char *)name
++;
2299 if (c
== '/' || c
== '\0')
2300 return ERR_PTR(-EACCES
);
2303 * See if the low-level filesystem might want
2304 * to use its own hash..
2306 if (base
->d_flags
& DCACHE_OP_HASH
) {
2307 int err
= base
->d_op
->d_hash(base
, &this);
2309 return ERR_PTR(err
);
2312 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
2314 return ERR_PTR(err
);
2316 return __lookup_hash(&this, base
, 0);
2318 EXPORT_SYMBOL(lookup_one_len
);
2321 * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
2322 * @name: pathname component to lookup
2323 * @base: base directory to lookup from
2324 * @len: maximum length @len should be interpreted to
2326 * Note that this routine is purely a helper for filesystem usage and should
2327 * not be called by generic code.
2329 * Unlike lookup_one_len, it should be called without the parent
2330 * i_mutex held, and will take the i_mutex itself if necessary.
2332 struct dentry
*lookup_one_len_unlocked(const char *name
,
2333 struct dentry
*base
, int len
)
2342 this.hash
= full_name_hash(name
, len
);
2344 return ERR_PTR(-EACCES
);
2346 if (unlikely(name
[0] == '.')) {
2347 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2348 return ERR_PTR(-EACCES
);
2352 c
= *(const unsigned char *)name
++;
2353 if (c
== '/' || c
== '\0')
2354 return ERR_PTR(-EACCES
);
2357 * See if the low-level filesystem might want
2358 * to use its own hash..
2360 if (base
->d_flags
& DCACHE_OP_HASH
) {
2361 int err
= base
->d_op
->d_hash(base
, &this);
2363 return ERR_PTR(err
);
2366 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
2368 return ERR_PTR(err
);
2370 ret
= lookup_dcache(&this, base
, 0);
2372 ret
= lookup_slow(&this, base
, 0);
2375 EXPORT_SYMBOL(lookup_one_len_unlocked
);
2377 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
2378 struct path
*path
, int *empty
)
2380 return filename_lookup(dfd
, getname_flags(name
, flags
, empty
),
2383 EXPORT_SYMBOL(user_path_at_empty
);
2386 * NB: most callers don't do anything directly with the reference to the
2387 * to struct filename, but the nd->last pointer points into the name string
2388 * allocated by getname. So we must hold the reference to it until all
2389 * path-walking is complete.
2391 static inline struct filename
*
2392 user_path_parent(int dfd
, const char __user
*path
,
2393 struct path
*parent
,
2398 /* only LOOKUP_REVAL is allowed in extra flags */
2399 return filename_parentat(dfd
, getname(path
), flags
& LOOKUP_REVAL
,
2400 parent
, last
, type
);
2404 * mountpoint_last - look up last component for umount
2405 * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
2406 * @path: pointer to container for result
2408 * This is a special lookup_last function just for umount. In this case, we
2409 * need to resolve the path without doing any revalidation.
2411 * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
2412 * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
2413 * in almost all cases, this lookup will be served out of the dcache. The only
2414 * cases where it won't are if nd->last refers to a symlink or the path is
2415 * bogus and it doesn't exist.
2418 * -error: if there was an error during lookup. This includes -ENOENT if the
2419 * lookup found a negative dentry. The nd->path reference will also be
2422 * 0: if we successfully resolved nd->path and found it to not to be a
2423 * symlink that needs to be followed. "path" will also be populated.
2424 * The nd->path reference will also be put.
2426 * 1: if we successfully resolved nd->last and found it to be a symlink
2427 * that needs to be followed. "path" will be populated with the path
2428 * to the link, and nd->path will *not* be put.
2431 mountpoint_last(struct nameidata
*nd
, struct path
*path
)
2434 struct dentry
*dentry
;
2435 struct dentry
*dir
= nd
->path
.dentry
;
2437 /* If we're in rcuwalk, drop out of it to handle last component */
2438 if (nd
->flags
& LOOKUP_RCU
) {
2439 if (unlazy_walk(nd
, NULL
, 0))
2443 nd
->flags
&= ~LOOKUP_PARENT
;
2445 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
2446 error
= handle_dots(nd
, nd
->last_type
);
2449 dentry
= dget(nd
->path
.dentry
);
2451 dentry
= d_lookup(dir
, &nd
->last
);
2454 * No cached dentry. Mounted dentries are pinned in the
2455 * cache, so that means that this dentry is probably
2456 * a symlink or the path doesn't actually point
2457 * to a mounted dentry.
2459 dentry
= lookup_slow(&nd
->last
, dir
,
2460 nd
->flags
| LOOKUP_NO_REVAL
);
2462 return PTR_ERR(dentry
);
2465 if (d_is_negative(dentry
)) {
2471 path
->dentry
= dentry
;
2472 path
->mnt
= nd
->path
.mnt
;
2473 error
= should_follow_link(nd
, path
, nd
->flags
& LOOKUP_FOLLOW
,
2474 d_backing_inode(dentry
), 0);
2475 if (unlikely(error
))
2483 * path_mountpoint - look up a path to be umounted
2484 * @nd: lookup context
2485 * @flags: lookup flags
2486 * @path: pointer to container for result
2488 * Look up the given name, but don't attempt to revalidate the last component.
2489 * Returns 0 and "path" will be valid on success; Returns error otherwise.
2492 path_mountpoint(struct nameidata
*nd
, unsigned flags
, struct path
*path
)
2494 const char *s
= path_init(nd
, flags
);
2498 while (!(err
= link_path_walk(s
, nd
)) &&
2499 (err
= mountpoint_last(nd
, path
)) > 0) {
2500 s
= trailing_symlink(nd
);
2511 filename_mountpoint(int dfd
, struct filename
*name
, struct path
*path
,
2514 struct nameidata nd
;
2517 return PTR_ERR(name
);
2518 set_nameidata(&nd
, dfd
, name
);
2519 error
= path_mountpoint(&nd
, flags
| LOOKUP_RCU
, path
);
2520 if (unlikely(error
== -ECHILD
))
2521 error
= path_mountpoint(&nd
, flags
, path
);
2522 if (unlikely(error
== -ESTALE
))
2523 error
= path_mountpoint(&nd
, flags
| LOOKUP_REVAL
, path
);
2525 audit_inode(name
, path
->dentry
, 0);
2526 restore_nameidata();
2532 * user_path_mountpoint_at - lookup a path from userland in order to umount it
2533 * @dfd: directory file descriptor
2534 * @name: pathname from userland
2535 * @flags: lookup flags
2536 * @path: pointer to container to hold result
2538 * A umount is a special case for path walking. We're not actually interested
2539 * in the inode in this situation, and ESTALE errors can be a problem. We
2540 * simply want track down the dentry and vfsmount attached at the mountpoint
2541 * and avoid revalidating the last component.
2543 * Returns 0 and populates "path" on success.
2546 user_path_mountpoint_at(int dfd
, const char __user
*name
, unsigned int flags
,
2549 return filename_mountpoint(dfd
, getname(name
), path
, flags
);
2553 kern_path_mountpoint(int dfd
, const char *name
, struct path
*path
,
2556 return filename_mountpoint(dfd
, getname_kernel(name
), path
, flags
);
2558 EXPORT_SYMBOL(kern_path_mountpoint
);
2560 int __check_sticky(struct inode
*dir
, struct inode
*inode
)
2562 kuid_t fsuid
= current_fsuid();
2564 if (uid_eq(inode
->i_uid
, fsuid
))
2566 if (uid_eq(dir
->i_uid
, fsuid
))
2568 return !capable_wrt_inode_uidgid(inode
, CAP_FOWNER
);
2570 EXPORT_SYMBOL(__check_sticky
);
2573 * Check whether we can remove a link victim from directory dir, check
2574 * whether the type of victim is right.
2575 * 1. We can't do it if dir is read-only (done in permission())
2576 * 2. We should have write and exec permissions on dir
2577 * 3. We can't remove anything from append-only dir
2578 * 4. We can't do anything with immutable dir (done in permission())
2579 * 5. If the sticky bit on dir is set we should either
2580 * a. be owner of dir, or
2581 * b. be owner of victim, or
2582 * c. have CAP_FOWNER capability
2583 * 6. If the victim is append-only or immutable we can't do antyhing with
2584 * links pointing to it.
2585 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2586 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2587 * 9. We can't remove a root or mountpoint.
2588 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
2589 * nfs_async_unlink().
2591 static int may_delete(struct inode
*dir
, struct dentry
*victim
, bool isdir
)
2593 struct inode
*inode
= d_backing_inode(victim
);
2596 if (d_is_negative(victim
))
2600 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
2601 audit_inode_child(dir
, victim
, AUDIT_TYPE_CHILD_DELETE
);
2603 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2609 if (check_sticky(dir
, inode
) || IS_APPEND(inode
) ||
2610 IS_IMMUTABLE(inode
) || IS_SWAPFILE(inode
))
2613 if (!d_is_dir(victim
))
2615 if (IS_ROOT(victim
))
2617 } else if (d_is_dir(victim
))
2619 if (IS_DEADDIR(dir
))
2621 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2626 /* Check whether we can create an object with dentry child in directory
2628 * 1. We can't do it if child already exists (open has special treatment for
2629 * this case, but since we are inlined it's OK)
2630 * 2. We can't do it if dir is read-only (done in permission())
2631 * 3. We should have write and exec permissions on dir
2632 * 4. We can't do it if dir is immutable (done in permission())
2634 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
2636 audit_inode_child(dir
, child
, AUDIT_TYPE_CHILD_CREATE
);
2639 if (IS_DEADDIR(dir
))
2641 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2645 * p1 and p2 should be directories on the same fs.
2647 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2652 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
2656 mutex_lock(&p1
->d_sb
->s_vfs_rename_mutex
);
2658 p
= d_ancestor(p2
, p1
);
2660 inode_lock_nested(p2
->d_inode
, I_MUTEX_PARENT
);
2661 inode_lock_nested(p1
->d_inode
, I_MUTEX_CHILD
);
2665 p
= d_ancestor(p1
, p2
);
2667 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
2668 inode_lock_nested(p2
->d_inode
, I_MUTEX_CHILD
);
2672 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
2673 inode_lock_nested(p2
->d_inode
, I_MUTEX_PARENT2
);
2676 EXPORT_SYMBOL(lock_rename
);
2678 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
2680 inode_unlock(p1
->d_inode
);
2682 inode_unlock(p2
->d_inode
);
2683 mutex_unlock(&p1
->d_sb
->s_vfs_rename_mutex
);
2686 EXPORT_SYMBOL(unlock_rename
);
2688 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
2691 int error
= may_create(dir
, dentry
);
2695 if (!dir
->i_op
->create
)
2696 return -EACCES
; /* shouldn't it be ENOSYS? */
2699 error
= security_inode_create(dir
, dentry
, mode
);
2702 error
= dir
->i_op
->create(dir
, dentry
, mode
, want_excl
);
2704 fsnotify_create(dir
, dentry
);
2707 EXPORT_SYMBOL(vfs_create
);
2709 static int may_open(struct path
*path
, int acc_mode
, int flag
)
2711 struct dentry
*dentry
= path
->dentry
;
2712 struct inode
*inode
= dentry
->d_inode
;
2718 switch (inode
->i_mode
& S_IFMT
) {
2722 if (acc_mode
& MAY_WRITE
)
2727 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
2736 error
= inode_permission(inode
, MAY_OPEN
| acc_mode
);
2741 * An append-only file must be opened in append mode for writing.
2743 if (IS_APPEND(inode
)) {
2744 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
2750 /* O_NOATIME can only be set by the owner or superuser */
2751 if (flag
& O_NOATIME
&& !inode_owner_or_capable(inode
))
2757 static int handle_truncate(struct file
*filp
)
2759 struct path
*path
= &filp
->f_path
;
2760 struct inode
*inode
= path
->dentry
->d_inode
;
2761 int error
= get_write_access(inode
);
2765 * Refuse to truncate files with mandatory locks held on them.
2767 error
= locks_verify_locked(filp
);
2769 error
= security_path_truncate(path
);
2771 error
= do_truncate(path
->dentry
, 0,
2772 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
2775 put_write_access(inode
);
2779 static inline int open_to_namei_flags(int flag
)
2781 if ((flag
& O_ACCMODE
) == 3)
2786 static int may_o_create(struct path
*dir
, struct dentry
*dentry
, umode_t mode
)
2788 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
2792 error
= inode_permission(dir
->dentry
->d_inode
, MAY_WRITE
| MAY_EXEC
);
2796 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
2800 * Attempt to atomically look up, create and open a file from a negative
2803 * Returns 0 if successful. The file will have been created and attached to
2804 * @file by the filesystem calling finish_open().
2806 * Returns 1 if the file was looked up only or didn't need creating. The
2807 * caller will need to perform the open themselves. @path will have been
2808 * updated to point to the new dentry. This may be negative.
2810 * Returns an error code otherwise.
2812 static int atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
2813 struct path
*path
, struct file
*file
,
2814 const struct open_flags
*op
,
2815 bool got_write
, bool need_lookup
,
2818 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
2819 unsigned open_flag
= open_to_namei_flags(op
->open_flag
);
2823 int create_error
= 0;
2824 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
2827 BUG_ON(dentry
->d_inode
);
2829 /* Don't create child dentry for a dead directory. */
2830 if (unlikely(IS_DEADDIR(dir
))) {
2836 if ((open_flag
& O_CREAT
) && !IS_POSIXACL(dir
))
2837 mode
&= ~current_umask();
2839 excl
= (open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
);
2841 open_flag
&= ~O_TRUNC
;
2844 * Checking write permission is tricky, bacuse we don't know if we are
2845 * going to actually need it: O_CREAT opens should work as long as the
2846 * file exists. But checking existence breaks atomicity. The trick is
2847 * to check access and if not granted clear O_CREAT from the flags.
2849 * Another problem is returing the "right" error value (e.g. for an
2850 * O_EXCL open we want to return EEXIST not EROFS).
2852 if (((open_flag
& (O_CREAT
| O_TRUNC
)) ||
2853 (open_flag
& O_ACCMODE
) != O_RDONLY
) && unlikely(!got_write
)) {
2854 if (!(open_flag
& O_CREAT
)) {
2856 * No O_CREATE -> atomicity not a requirement -> fall
2857 * back to lookup + open
2860 } else if (open_flag
& (O_EXCL
| O_TRUNC
)) {
2861 /* Fall back and fail with the right error */
2862 create_error
= -EROFS
;
2865 /* No side effects, safe to clear O_CREAT */
2866 create_error
= -EROFS
;
2867 open_flag
&= ~O_CREAT
;
2871 if (open_flag
& O_CREAT
) {
2872 error
= may_o_create(&nd
->path
, dentry
, mode
);
2874 create_error
= error
;
2875 if (open_flag
& O_EXCL
)
2877 open_flag
&= ~O_CREAT
;
2881 if (nd
->flags
& LOOKUP_DIRECTORY
)
2882 open_flag
|= O_DIRECTORY
;
2884 file
->f_path
.dentry
= DENTRY_NOT_SET
;
2885 file
->f_path
.mnt
= nd
->path
.mnt
;
2886 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
, open_flag
, mode
,
2889 if (create_error
&& error
== -ENOENT
)
2890 error
= create_error
;
2894 if (error
) { /* returned 1, that is */
2895 if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
2899 if (file
->f_path
.dentry
) {
2901 dentry
= file
->f_path
.dentry
;
2903 if (*opened
& FILE_CREATED
)
2904 fsnotify_create(dir
, dentry
);
2905 if (!dentry
->d_inode
) {
2906 WARN_ON(*opened
& FILE_CREATED
);
2908 error
= create_error
;
2912 if (excl
&& !(*opened
& FILE_CREATED
)) {
2921 * We didn't have the inode before the open, so check open permission
2924 acc_mode
= op
->acc_mode
;
2925 if (*opened
& FILE_CREATED
) {
2926 WARN_ON(!(open_flag
& O_CREAT
));
2927 fsnotify_create(dir
, dentry
);
2930 error
= may_open(&file
->f_path
, acc_mode
, open_flag
);
2940 dentry
= lookup_real(dir
, dentry
, nd
->flags
);
2942 return PTR_ERR(dentry
);
2945 int open_flag
= op
->open_flag
;
2947 error
= create_error
;
2948 if ((open_flag
& O_EXCL
)) {
2949 if (!dentry
->d_inode
)
2951 } else if (!dentry
->d_inode
) {
2953 } else if ((open_flag
& O_TRUNC
) &&
2957 /* will fail later, go on to get the right error */
2961 path
->dentry
= dentry
;
2962 path
->mnt
= nd
->path
.mnt
;
2967 * Look up and maybe create and open the last component.
2969 * Must be called with i_mutex held on parent.
2971 * Returns 0 if the file was successfully atomically created (if necessary) and
2972 * opened. In this case the file will be returned attached to @file.
2974 * Returns 1 if the file was not completely opened at this time, though lookups
2975 * and creations will have been performed and the dentry returned in @path will
2976 * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
2977 * specified then a negative dentry may be returned.
2979 * An error code is returned otherwise.
2981 * FILE_CREATE will be set in @*opened if the dentry was created and will be
2982 * cleared otherwise prior to returning.
2984 static int lookup_open(struct nameidata
*nd
, struct path
*path
,
2986 const struct open_flags
*op
,
2987 bool got_write
, int *opened
)
2989 struct dentry
*dir
= nd
->path
.dentry
;
2990 struct inode
*dir_inode
= dir
->d_inode
;
2991 struct dentry
*dentry
;
2993 bool need_lookup
= false;
2995 *opened
&= ~FILE_CREATED
;
2996 dentry
= lookup_dcache(&nd
->last
, dir
, nd
->flags
);
2998 return PTR_ERR(dentry
);
3001 dentry
= d_alloc(dir
, &nd
->last
);
3002 if (unlikely(!dentry
))
3005 } else if (dentry
->d_inode
) {
3006 /* Cached positive dentry: will open in f_op->open */
3010 if ((nd
->flags
& LOOKUP_OPEN
) && dir_inode
->i_op
->atomic_open
) {
3011 return atomic_open(nd
, dentry
, path
, file
, op
, got_write
,
3012 need_lookup
, opened
);
3016 BUG_ON(dentry
->d_inode
);
3018 dentry
= lookup_real(dir_inode
, dentry
, nd
->flags
);
3020 return PTR_ERR(dentry
);
3023 /* Negative dentry, just create the file */
3024 if (!dentry
->d_inode
&& (op
->open_flag
& O_CREAT
)) {
3025 umode_t mode
= op
->mode
;
3026 if (!IS_POSIXACL(dir
->d_inode
))
3027 mode
&= ~current_umask();
3029 * This write is needed to ensure that a
3030 * rw->ro transition does not occur between
3031 * the time when the file is created and when
3032 * a permanent write count is taken through
3033 * the 'struct file' in finish_open().
3039 *opened
|= FILE_CREATED
;
3040 error
= security_path_mknod(&nd
->path
, dentry
, mode
, 0);
3043 error
= vfs_create(dir
->d_inode
, dentry
, mode
,
3044 nd
->flags
& LOOKUP_EXCL
);
3049 path
->dentry
= dentry
;
3050 path
->mnt
= nd
->path
.mnt
;
3059 * Handle the last step of open()
3061 static int do_last(struct nameidata
*nd
,
3062 struct file
*file
, const struct open_flags
*op
,
3065 struct dentry
*dir
= nd
->path
.dentry
;
3066 int open_flag
= op
->open_flag
;
3067 bool will_truncate
= (open_flag
& O_TRUNC
) != 0;
3068 bool got_write
= false;
3069 int acc_mode
= op
->acc_mode
;
3071 struct inode
*inode
;
3072 struct path save_parent
= { .dentry
= NULL
, .mnt
= NULL
};
3074 bool retried
= false;
3077 nd
->flags
&= ~LOOKUP_PARENT
;
3078 nd
->flags
|= op
->intent
;
3080 if (nd
->last_type
!= LAST_NORM
) {
3081 error
= handle_dots(nd
, nd
->last_type
);
3082 if (unlikely(error
))
3087 if (!(open_flag
& O_CREAT
)) {
3088 if (nd
->last
.name
[nd
->last
.len
])
3089 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
3090 /* we _can_ be in RCU mode here */
3091 error
= lookup_fast(nd
, &path
, &inode
, &seq
);
3092 if (likely(error
> 0))
3098 BUG_ON(nd
->inode
!= dir
->d_inode
);
3099 BUG_ON(nd
->flags
& LOOKUP_RCU
);
3101 /* create side of things */
3103 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
3104 * has been cleared when we got to the last component we are
3107 error
= complete_walk(nd
);
3111 audit_inode(nd
->name
, dir
, LOOKUP_PARENT
);
3112 /* trailing slashes? */
3113 if (unlikely(nd
->last
.name
[nd
->last
.len
]))
3118 if (op
->open_flag
& (O_CREAT
| O_TRUNC
| O_WRONLY
| O_RDWR
)) {
3119 error
= mnt_want_write(nd
->path
.mnt
);
3123 * do _not_ fail yet - we might not need that or fail with
3124 * a different error; let lookup_open() decide; we'll be
3125 * dropping this one anyway.
3128 inode_lock(dir
->d_inode
);
3129 error
= lookup_open(nd
, &path
, file
, op
, got_write
, opened
);
3130 inode_unlock(dir
->d_inode
);
3136 if ((*opened
& FILE_CREATED
) ||
3137 !S_ISREG(file_inode(file
)->i_mode
))
3138 will_truncate
= false;
3140 audit_inode(nd
->name
, file
->f_path
.dentry
, 0);
3144 if (*opened
& FILE_CREATED
) {
3145 /* Don't check for write permission, don't truncate */
3146 open_flag
&= ~O_TRUNC
;
3147 will_truncate
= false;
3149 path_to_nameidata(&path
, nd
);
3150 goto finish_open_created
;
3154 * If atomic_open() acquired write access it is dropped now due to
3155 * possible mount and symlink following (this might be optimized away if
3159 mnt_drop_write(nd
->path
.mnt
);
3163 if (unlikely(d_is_negative(path
.dentry
))) {
3164 path_to_nameidata(&path
, nd
);
3169 * create/update audit record if it already exists.
3171 audit_inode(nd
->name
, path
.dentry
, 0);
3173 if (unlikely((open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
))) {
3174 path_to_nameidata(&path
, nd
);
3178 error
= follow_managed(&path
, nd
);
3179 if (unlikely(error
< 0))
3182 seq
= 0; /* out of RCU mode, so the value doesn't matter */
3183 inode
= d_backing_inode(path
.dentry
);
3187 error
= should_follow_link(nd
, &path
, nd
->flags
& LOOKUP_FOLLOW
,
3189 if (unlikely(error
))
3192 if ((nd
->flags
& LOOKUP_RCU
) || nd
->path
.mnt
!= path
.mnt
) {
3193 path_to_nameidata(&path
, nd
);
3195 save_parent
.dentry
= nd
->path
.dentry
;
3196 save_parent
.mnt
= mntget(path
.mnt
);
3197 nd
->path
.dentry
= path
.dentry
;
3202 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
3204 error
= complete_walk(nd
);
3206 path_put(&save_parent
);
3209 audit_inode(nd
->name
, nd
->path
.dentry
, 0);
3210 if (unlikely(d_is_symlink(nd
->path
.dentry
)) && !(open_flag
& O_PATH
)) {
3215 if ((open_flag
& O_CREAT
) && d_is_dir(nd
->path
.dentry
))
3218 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !d_can_lookup(nd
->path
.dentry
))
3220 if (!d_is_reg(nd
->path
.dentry
))
3221 will_truncate
= false;
3223 if (will_truncate
) {
3224 error
= mnt_want_write(nd
->path
.mnt
);
3229 finish_open_created
:
3230 if (likely(!(open_flag
& O_PATH
))) {
3231 error
= may_open(&nd
->path
, acc_mode
, open_flag
);
3235 BUG_ON(*opened
& FILE_OPENED
); /* once it's opened, it's opened */
3236 error
= vfs_open(&nd
->path
, file
, current_cred());
3238 *opened
|= FILE_OPENED
;
3240 if (error
== -EOPENSTALE
)
3245 error
= open_check_o_direct(file
);
3248 error
= ima_file_check(file
, op
->acc_mode
, *opened
);
3252 if (will_truncate
) {
3253 error
= handle_truncate(file
);
3258 if (unlikely(error
> 0)) {
3263 mnt_drop_write(nd
->path
.mnt
);
3264 path_put(&save_parent
);
3272 /* If no saved parent or already retried then can't retry */
3273 if (!save_parent
.dentry
|| retried
)
3276 BUG_ON(save_parent
.dentry
!= dir
);
3277 path_put(&nd
->path
);
3278 nd
->path
= save_parent
;
3279 nd
->inode
= dir
->d_inode
;
3280 save_parent
.mnt
= NULL
;
3281 save_parent
.dentry
= NULL
;
3283 mnt_drop_write(nd
->path
.mnt
);
3290 static int do_tmpfile(struct nameidata
*nd
, unsigned flags
,
3291 const struct open_flags
*op
,
3292 struct file
*file
, int *opened
)
3294 static const struct qstr name
= QSTR_INIT("/", 1);
3295 struct dentry
*child
;
3298 int error
= path_lookupat(nd
, flags
| LOOKUP_DIRECTORY
, &path
);
3299 if (unlikely(error
))
3301 error
= mnt_want_write(path
.mnt
);
3302 if (unlikely(error
))
3304 dir
= path
.dentry
->d_inode
;
3305 /* we want directory to be writable */
3306 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
3309 if (!dir
->i_op
->tmpfile
) {
3310 error
= -EOPNOTSUPP
;
3313 child
= d_alloc(path
.dentry
, &name
);
3314 if (unlikely(!child
)) {
3319 path
.dentry
= child
;
3320 error
= dir
->i_op
->tmpfile(dir
, child
, op
->mode
);
3323 audit_inode(nd
->name
, child
, 0);
3324 /* Don't check for other permissions, the inode was just created */
3325 error
= may_open(&path
, 0, op
->open_flag
);
3328 file
->f_path
.mnt
= path
.mnt
;
3329 error
= finish_open(file
, child
, NULL
, opened
);
3332 error
= open_check_o_direct(file
);
3335 } else if (!(op
->open_flag
& O_EXCL
)) {
3336 struct inode
*inode
= file_inode(file
);
3337 spin_lock(&inode
->i_lock
);
3338 inode
->i_state
|= I_LINKABLE
;
3339 spin_unlock(&inode
->i_lock
);
3342 mnt_drop_write(path
.mnt
);
3348 static struct file
*path_openat(struct nameidata
*nd
,
3349 const struct open_flags
*op
, unsigned flags
)
3356 file
= get_empty_filp();
3360 file
->f_flags
= op
->open_flag
;
3362 if (unlikely(file
->f_flags
& __O_TMPFILE
)) {
3363 error
= do_tmpfile(nd
, flags
, op
, file
, &opened
);
3367 s
= path_init(nd
, flags
);
3372 while (!(error
= link_path_walk(s
, nd
)) &&
3373 (error
= do_last(nd
, file
, op
, &opened
)) > 0) {
3374 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
3375 s
= trailing_symlink(nd
);
3383 if (!(opened
& FILE_OPENED
)) {
3387 if (unlikely(error
)) {
3388 if (error
== -EOPENSTALE
) {
3389 if (flags
& LOOKUP_RCU
)
3394 file
= ERR_PTR(error
);
3399 struct file
*do_filp_open(int dfd
, struct filename
*pathname
,
3400 const struct open_flags
*op
)
3402 struct nameidata nd
;
3403 int flags
= op
->lookup_flags
;
3406 set_nameidata(&nd
, dfd
, pathname
);
3407 filp
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3408 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
3409 filp
= path_openat(&nd
, op
, flags
);
3410 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
3411 filp
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3412 restore_nameidata();
3416 struct file
*do_file_open_root(struct dentry
*dentry
, struct vfsmount
*mnt
,
3417 const char *name
, const struct open_flags
*op
)
3419 struct nameidata nd
;
3421 struct filename
*filename
;
3422 int flags
= op
->lookup_flags
| LOOKUP_ROOT
;
3425 nd
.root
.dentry
= dentry
;
3427 if (d_is_symlink(dentry
) && op
->intent
& LOOKUP_OPEN
)
3428 return ERR_PTR(-ELOOP
);
3430 filename
= getname_kernel(name
);
3431 if (IS_ERR(filename
))
3432 return ERR_CAST(filename
);
3434 set_nameidata(&nd
, -1, filename
);
3435 file
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3436 if (unlikely(file
== ERR_PTR(-ECHILD
)))
3437 file
= path_openat(&nd
, op
, flags
);
3438 if (unlikely(file
== ERR_PTR(-ESTALE
)))
3439 file
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3440 restore_nameidata();
3445 static struct dentry
*filename_create(int dfd
, struct filename
*name
,
3446 struct path
*path
, unsigned int lookup_flags
)
3448 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
3453 bool is_dir
= (lookup_flags
& LOOKUP_DIRECTORY
);
3456 * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
3457 * other flags passed in are ignored!
3459 lookup_flags
&= LOOKUP_REVAL
;
3461 name
= filename_parentat(dfd
, name
, lookup_flags
, path
, &last
, &type
);
3463 return ERR_CAST(name
);
3466 * Yucky last component or no last component at all?
3467 * (foo/., foo/.., /////)
3469 if (unlikely(type
!= LAST_NORM
))
3472 /* don't fail immediately if it's r/o, at least try to report other errors */
3473 err2
= mnt_want_write(path
->mnt
);
3475 * Do the final lookup.
3477 lookup_flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
3478 inode_lock_nested(path
->dentry
->d_inode
, I_MUTEX_PARENT
);
3479 dentry
= __lookup_hash(&last
, path
->dentry
, lookup_flags
);
3484 if (d_is_positive(dentry
))
3488 * Special case - lookup gave negative, but... we had foo/bar/
3489 * From the vfs_mknod() POV we just have a negative dentry -
3490 * all is fine. Let's be bastards - you had / on the end, you've
3491 * been asking for (non-existent) directory. -ENOENT for you.
3493 if (unlikely(!is_dir
&& last
.name
[last
.len
])) {
3497 if (unlikely(err2
)) {
3505 dentry
= ERR_PTR(error
);
3507 inode_unlock(path
->dentry
->d_inode
);
3509 mnt_drop_write(path
->mnt
);
3516 struct dentry
*kern_path_create(int dfd
, const char *pathname
,
3517 struct path
*path
, unsigned int lookup_flags
)
3519 return filename_create(dfd
, getname_kernel(pathname
),
3520 path
, lookup_flags
);
3522 EXPORT_SYMBOL(kern_path_create
);
3524 void done_path_create(struct path
*path
, struct dentry
*dentry
)
3527 inode_unlock(path
->dentry
->d_inode
);
3528 mnt_drop_write(path
->mnt
);
3531 EXPORT_SYMBOL(done_path_create
);
3533 inline struct dentry
*user_path_create(int dfd
, const char __user
*pathname
,
3534 struct path
*path
, unsigned int lookup_flags
)
3536 return filename_create(dfd
, getname(pathname
), path
, lookup_flags
);
3538 EXPORT_SYMBOL(user_path_create
);
3540 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3542 int error
= may_create(dir
, dentry
);
3547 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
3550 if (!dir
->i_op
->mknod
)
3553 error
= devcgroup_inode_mknod(mode
, dev
);
3557 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
3561 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
3563 fsnotify_create(dir
, dentry
);
3566 EXPORT_SYMBOL(vfs_mknod
);
3568 static int may_mknod(umode_t mode
)
3570 switch (mode
& S_IFMT
) {
3576 case 0: /* zero mode translates to S_IFREG */
3585 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
3588 struct dentry
*dentry
;
3591 unsigned int lookup_flags
= 0;
3593 error
= may_mknod(mode
);
3597 dentry
= user_path_create(dfd
, filename
, &path
, lookup_flags
);
3599 return PTR_ERR(dentry
);
3601 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3602 mode
&= ~current_umask();
3603 error
= security_path_mknod(&path
, dentry
, mode
, dev
);
3606 switch (mode
& S_IFMT
) {
3607 case 0: case S_IFREG
:
3608 error
= vfs_create(path
.dentry
->d_inode
,dentry
,mode
,true);
3610 case S_IFCHR
: case S_IFBLK
:
3611 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,
3612 new_decode_dev(dev
));
3614 case S_IFIFO
: case S_IFSOCK
:
3615 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,0);
3619 done_path_create(&path
, dentry
);
3620 if (retry_estale(error
, lookup_flags
)) {
3621 lookup_flags
|= LOOKUP_REVAL
;
3627 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
3629 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
3632 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
3634 int error
= may_create(dir
, dentry
);
3635 unsigned max_links
= dir
->i_sb
->s_max_links
;
3640 if (!dir
->i_op
->mkdir
)
3643 mode
&= (S_IRWXUGO
|S_ISVTX
);
3644 error
= security_inode_mkdir(dir
, dentry
, mode
);
3648 if (max_links
&& dir
->i_nlink
>= max_links
)
3651 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
3653 fsnotify_mkdir(dir
, dentry
);
3656 EXPORT_SYMBOL(vfs_mkdir
);
3658 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, umode_t
, mode
)
3660 struct dentry
*dentry
;
3663 unsigned int lookup_flags
= LOOKUP_DIRECTORY
;
3666 dentry
= user_path_create(dfd
, pathname
, &path
, lookup_flags
);
3668 return PTR_ERR(dentry
);
3670 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3671 mode
&= ~current_umask();
3672 error
= security_path_mkdir(&path
, dentry
, mode
);
3674 error
= vfs_mkdir(path
.dentry
->d_inode
, dentry
, mode
);
3675 done_path_create(&path
, dentry
);
3676 if (retry_estale(error
, lookup_flags
)) {
3677 lookup_flags
|= LOOKUP_REVAL
;
3683 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, umode_t
, mode
)
3685 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
3688 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
3690 int error
= may_delete(dir
, dentry
, 1);
3695 if (!dir
->i_op
->rmdir
)
3699 inode_lock(dentry
->d_inode
);
3702 if (is_local_mountpoint(dentry
))
3705 error
= security_inode_rmdir(dir
, dentry
);
3709 shrink_dcache_parent(dentry
);
3710 error
= dir
->i_op
->rmdir(dir
, dentry
);
3714 dentry
->d_inode
->i_flags
|= S_DEAD
;
3716 detach_mounts(dentry
);
3719 inode_unlock(dentry
->d_inode
);
3725 EXPORT_SYMBOL(vfs_rmdir
);
3727 static long do_rmdir(int dfd
, const char __user
*pathname
)
3730 struct filename
*name
;
3731 struct dentry
*dentry
;
3735 unsigned int lookup_flags
= 0;
3737 name
= user_path_parent(dfd
, pathname
,
3738 &path
, &last
, &type
, lookup_flags
);
3740 return PTR_ERR(name
);
3754 error
= mnt_want_write(path
.mnt
);
3758 inode_lock_nested(path
.dentry
->d_inode
, I_MUTEX_PARENT
);
3759 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3760 error
= PTR_ERR(dentry
);
3763 if (!dentry
->d_inode
) {
3767 error
= security_path_rmdir(&path
, dentry
);
3770 error
= vfs_rmdir(path
.dentry
->d_inode
, dentry
);
3774 inode_unlock(path
.dentry
->d_inode
);
3775 mnt_drop_write(path
.mnt
);
3779 if (retry_estale(error
, lookup_flags
)) {
3780 lookup_flags
|= LOOKUP_REVAL
;
3786 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
3788 return do_rmdir(AT_FDCWD
, pathname
);
3792 * vfs_unlink - unlink a filesystem object
3793 * @dir: parent directory
3795 * @delegated_inode: returns victim inode, if the inode is delegated.
3797 * The caller must hold dir->i_mutex.
3799 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
3800 * return a reference to the inode in delegated_inode. The caller
3801 * should then break the delegation on that inode and retry. Because
3802 * breaking a delegation may take a long time, the caller should drop
3803 * dir->i_mutex before doing so.
3805 * Alternatively, a caller may pass NULL for delegated_inode. This may
3806 * be appropriate for callers that expect the underlying filesystem not
3807 * to be NFS exported.
3809 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
, struct inode
**delegated_inode
)
3811 struct inode
*target
= dentry
->d_inode
;
3812 int error
= may_delete(dir
, dentry
, 0);
3817 if (!dir
->i_op
->unlink
)
3821 if (is_local_mountpoint(dentry
))
3824 error
= security_inode_unlink(dir
, dentry
);
3826 error
= try_break_deleg(target
, delegated_inode
);
3829 error
= dir
->i_op
->unlink(dir
, dentry
);
3832 detach_mounts(dentry
);
3837 inode_unlock(target
);
3839 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
3840 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
3841 fsnotify_link_count(target
);
3847 EXPORT_SYMBOL(vfs_unlink
);
3850 * Make sure that the actual truncation of the file will occur outside its
3851 * directory's i_mutex. Truncate can take a long time if there is a lot of
3852 * writeout happening, and we don't want to prevent access to the directory
3853 * while waiting on the I/O.
3855 static long do_unlinkat(int dfd
, const char __user
*pathname
)
3858 struct filename
*name
;
3859 struct dentry
*dentry
;
3863 struct inode
*inode
= NULL
;
3864 struct inode
*delegated_inode
= NULL
;
3865 unsigned int lookup_flags
= 0;
3867 name
= user_path_parent(dfd
, pathname
,
3868 &path
, &last
, &type
, lookup_flags
);
3870 return PTR_ERR(name
);
3873 if (type
!= LAST_NORM
)
3876 error
= mnt_want_write(path
.mnt
);
3880 inode_lock_nested(path
.dentry
->d_inode
, I_MUTEX_PARENT
);
3881 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3882 error
= PTR_ERR(dentry
);
3883 if (!IS_ERR(dentry
)) {
3884 /* Why not before? Because we want correct error value */
3885 if (last
.name
[last
.len
])
3887 inode
= dentry
->d_inode
;
3888 if (d_is_negative(dentry
))
3891 error
= security_path_unlink(&path
, dentry
);
3894 error
= vfs_unlink(path
.dentry
->d_inode
, dentry
, &delegated_inode
);
3898 inode_unlock(path
.dentry
->d_inode
);
3900 iput(inode
); /* truncate the inode here */
3902 if (delegated_inode
) {
3903 error
= break_deleg_wait(&delegated_inode
);
3907 mnt_drop_write(path
.mnt
);
3911 if (retry_estale(error
, lookup_flags
)) {
3912 lookup_flags
|= LOOKUP_REVAL
;
3919 if (d_is_negative(dentry
))
3921 else if (d_is_dir(dentry
))
3928 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
3930 if ((flag
& ~AT_REMOVEDIR
) != 0)
3933 if (flag
& AT_REMOVEDIR
)
3934 return do_rmdir(dfd
, pathname
);
3936 return do_unlinkat(dfd
, pathname
);
3939 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
3941 return do_unlinkat(AT_FDCWD
, pathname
);
3944 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
3946 int error
= may_create(dir
, dentry
);
3951 if (!dir
->i_op
->symlink
)
3954 error
= security_inode_symlink(dir
, dentry
, oldname
);
3958 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
3960 fsnotify_create(dir
, dentry
);
3963 EXPORT_SYMBOL(vfs_symlink
);
3965 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
3966 int, newdfd
, const char __user
*, newname
)
3969 struct filename
*from
;
3970 struct dentry
*dentry
;
3972 unsigned int lookup_flags
= 0;
3974 from
= getname(oldname
);
3976 return PTR_ERR(from
);
3978 dentry
= user_path_create(newdfd
, newname
, &path
, lookup_flags
);
3979 error
= PTR_ERR(dentry
);
3983 error
= security_path_symlink(&path
, dentry
, from
->name
);
3985 error
= vfs_symlink(path
.dentry
->d_inode
, dentry
, from
->name
);
3986 done_path_create(&path
, dentry
);
3987 if (retry_estale(error
, lookup_flags
)) {
3988 lookup_flags
|= LOOKUP_REVAL
;
3996 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
3998 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
4002 * vfs_link - create a new link
4003 * @old_dentry: object to be linked
4005 * @new_dentry: where to create the new link
4006 * @delegated_inode: returns inode needing a delegation break
4008 * The caller must hold dir->i_mutex
4010 * If vfs_link discovers a delegation on the to-be-linked file in need
4011 * of breaking, it will return -EWOULDBLOCK and return a reference to the
4012 * inode in delegated_inode. The caller should then break the delegation
4013 * and retry. Because breaking a delegation may take a long time, the
4014 * caller should drop the i_mutex before doing so.
4016 * Alternatively, a caller may pass NULL for delegated_inode. This may
4017 * be appropriate for callers that expect the underlying filesystem not
4018 * to be NFS exported.
4020 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
, struct inode
**delegated_inode
)
4022 struct inode
*inode
= old_dentry
->d_inode
;
4023 unsigned max_links
= dir
->i_sb
->s_max_links
;
4029 error
= may_create(dir
, new_dentry
);
4033 if (dir
->i_sb
!= inode
->i_sb
)
4037 * A link to an append-only or immutable file cannot be created.
4039 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
4041 if (!dir
->i_op
->link
)
4043 if (S_ISDIR(inode
->i_mode
))
4046 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
4051 /* Make sure we don't allow creating hardlink to an unlinked file */
4052 if (inode
->i_nlink
== 0 && !(inode
->i_state
& I_LINKABLE
))
4054 else if (max_links
&& inode
->i_nlink
>= max_links
)
4057 error
= try_break_deleg(inode
, delegated_inode
);
4059 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
4062 if (!error
&& (inode
->i_state
& I_LINKABLE
)) {
4063 spin_lock(&inode
->i_lock
);
4064 inode
->i_state
&= ~I_LINKABLE
;
4065 spin_unlock(&inode
->i_lock
);
4067 inode_unlock(inode
);
4069 fsnotify_link(dir
, inode
, new_dentry
);
4072 EXPORT_SYMBOL(vfs_link
);
4075 * Hardlinks are often used in delicate situations. We avoid
4076 * security-related surprises by not following symlinks on the
4079 * We don't follow them on the oldname either to be compatible
4080 * with linux 2.0, and to avoid hard-linking to directories
4081 * and other special files. --ADM
4083 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
4084 int, newdfd
, const char __user
*, newname
, int, flags
)
4086 struct dentry
*new_dentry
;
4087 struct path old_path
, new_path
;
4088 struct inode
*delegated_inode
= NULL
;
4092 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0)
4095 * To use null names we require CAP_DAC_READ_SEARCH
4096 * This ensures that not everyone will be able to create
4097 * handlink using the passed filedescriptor.
4099 if (flags
& AT_EMPTY_PATH
) {
4100 if (!capable(CAP_DAC_READ_SEARCH
))
4105 if (flags
& AT_SYMLINK_FOLLOW
)
4106 how
|= LOOKUP_FOLLOW
;
4108 error
= user_path_at(olddfd
, oldname
, how
, &old_path
);
4112 new_dentry
= user_path_create(newdfd
, newname
, &new_path
,
4113 (how
& LOOKUP_REVAL
));
4114 error
= PTR_ERR(new_dentry
);
4115 if (IS_ERR(new_dentry
))
4119 if (old_path
.mnt
!= new_path
.mnt
)
4121 error
= may_linkat(&old_path
);
4122 if (unlikely(error
))
4124 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
4127 error
= vfs_link(old_path
.dentry
, new_path
.dentry
->d_inode
, new_dentry
, &delegated_inode
);
4129 done_path_create(&new_path
, new_dentry
);
4130 if (delegated_inode
) {
4131 error
= break_deleg_wait(&delegated_inode
);
4133 path_put(&old_path
);
4137 if (retry_estale(error
, how
)) {
4138 path_put(&old_path
);
4139 how
|= LOOKUP_REVAL
;
4143 path_put(&old_path
);
4148 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
4150 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4154 * vfs_rename - rename a filesystem object
4155 * @old_dir: parent of source
4156 * @old_dentry: source
4157 * @new_dir: parent of destination
4158 * @new_dentry: destination
4159 * @delegated_inode: returns an inode needing a delegation break
4160 * @flags: rename flags
4162 * The caller must hold multiple mutexes--see lock_rename()).
4164 * If vfs_rename discovers a delegation in need of breaking at either
4165 * the source or destination, it will return -EWOULDBLOCK and return a
4166 * reference to the inode in delegated_inode. The caller should then
4167 * break the delegation and retry. Because breaking a delegation may
4168 * take a long time, the caller should drop all locks before doing
4171 * Alternatively, a caller may pass NULL for delegated_inode. This may
4172 * be appropriate for callers that expect the underlying filesystem not
4173 * to be NFS exported.
4175 * The worst of all namespace operations - renaming directory. "Perverted"
4176 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4178 * a) we can get into loop creation.
4179 * b) race potential - two innocent renames can create a loop together.
4180 * That's where 4.4 screws up. Current fix: serialization on
4181 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
4183 * c) we have to lock _four_ objects - parents and victim (if it exists),
4184 * and source (if it is not a directory).
4185 * And that - after we got ->i_mutex on parents (until then we don't know
4186 * whether the target exists). Solution: try to be smart with locking
4187 * order for inodes. We rely on the fact that tree topology may change
4188 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
4189 * move will be locked. Thus we can rank directories by the tree
4190 * (ancestors first) and rank all non-directories after them.
4191 * That works since everybody except rename does "lock parent, lookup,
4192 * lock child" and rename is under ->s_vfs_rename_mutex.
4193 * HOWEVER, it relies on the assumption that any object with ->lookup()
4194 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4195 * we'd better make sure that there's no link(2) for them.
4196 * d) conversion from fhandle to dentry may come in the wrong moment - when
4197 * we are removing the target. Solution: we will have to grab ->i_mutex
4198 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
4199 * ->i_mutex on parents, which works but leads to some truly excessive
4202 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
4203 struct inode
*new_dir
, struct dentry
*new_dentry
,
4204 struct inode
**delegated_inode
, unsigned int flags
)
4207 bool is_dir
= d_is_dir(old_dentry
);
4208 const unsigned char *old_name
;
4209 struct inode
*source
= old_dentry
->d_inode
;
4210 struct inode
*target
= new_dentry
->d_inode
;
4211 bool new_is_dir
= false;
4212 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
4214 if (source
== target
)
4217 error
= may_delete(old_dir
, old_dentry
, is_dir
);
4222 error
= may_create(new_dir
, new_dentry
);
4224 new_is_dir
= d_is_dir(new_dentry
);
4226 if (!(flags
& RENAME_EXCHANGE
))
4227 error
= may_delete(new_dir
, new_dentry
, is_dir
);
4229 error
= may_delete(new_dir
, new_dentry
, new_is_dir
);
4234 if (!old_dir
->i_op
->rename
&& !old_dir
->i_op
->rename2
)
4237 if (flags
&& !old_dir
->i_op
->rename2
)
4241 * If we are going to change the parent - check write permissions,
4242 * we'll need to flip '..'.
4244 if (new_dir
!= old_dir
) {
4246 error
= inode_permission(source
, MAY_WRITE
);
4250 if ((flags
& RENAME_EXCHANGE
) && new_is_dir
) {
4251 error
= inode_permission(target
, MAY_WRITE
);
4257 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
,
4262 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
4264 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4265 lock_two_nondirectories(source
, target
);
4270 if (is_local_mountpoint(old_dentry
) || is_local_mountpoint(new_dentry
))
4273 if (max_links
&& new_dir
!= old_dir
) {
4275 if (is_dir
&& !new_is_dir
&& new_dir
->i_nlink
>= max_links
)
4277 if ((flags
& RENAME_EXCHANGE
) && !is_dir
&& new_is_dir
&&
4278 old_dir
->i_nlink
>= max_links
)
4281 if (is_dir
&& !(flags
& RENAME_EXCHANGE
) && target
)
4282 shrink_dcache_parent(new_dentry
);
4284 error
= try_break_deleg(source
, delegated_inode
);
4288 if (target
&& !new_is_dir
) {
4289 error
= try_break_deleg(target
, delegated_inode
);
4293 if (!old_dir
->i_op
->rename2
) {
4294 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
,
4295 new_dir
, new_dentry
);
4297 WARN_ON(old_dir
->i_op
->rename
!= NULL
);
4298 error
= old_dir
->i_op
->rename2(old_dir
, old_dentry
,
4299 new_dir
, new_dentry
, flags
);
4304 if (!(flags
& RENAME_EXCHANGE
) && target
) {
4306 target
->i_flags
|= S_DEAD
;
4307 dont_mount(new_dentry
);
4308 detach_mounts(new_dentry
);
4310 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
)) {
4311 if (!(flags
& RENAME_EXCHANGE
))
4312 d_move(old_dentry
, new_dentry
);
4314 d_exchange(old_dentry
, new_dentry
);
4317 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4318 unlock_two_nondirectories(source
, target
);
4320 inode_unlock(target
);
4323 fsnotify_move(old_dir
, new_dir
, old_name
, is_dir
,
4324 !(flags
& RENAME_EXCHANGE
) ? target
: NULL
, old_dentry
);
4325 if (flags
& RENAME_EXCHANGE
) {
4326 fsnotify_move(new_dir
, old_dir
, old_dentry
->d_name
.name
,
4327 new_is_dir
, NULL
, new_dentry
);
4330 fsnotify_oldname_free(old_name
);
4334 EXPORT_SYMBOL(vfs_rename
);
4336 SYSCALL_DEFINE5(renameat2
, int, olddfd
, const char __user
*, oldname
,
4337 int, newdfd
, const char __user
*, newname
, unsigned int, flags
)
4339 struct dentry
*old_dentry
, *new_dentry
;
4340 struct dentry
*trap
;
4341 struct path old_path
, new_path
;
4342 struct qstr old_last
, new_last
;
4343 int old_type
, new_type
;
4344 struct inode
*delegated_inode
= NULL
;
4345 struct filename
*from
;
4346 struct filename
*to
;
4347 unsigned int lookup_flags
= 0, target_flags
= LOOKUP_RENAME_TARGET
;
4348 bool should_retry
= false;
4351 if (flags
& ~(RENAME_NOREPLACE
| RENAME_EXCHANGE
| RENAME_WHITEOUT
))
4354 if ((flags
& (RENAME_NOREPLACE
| RENAME_WHITEOUT
)) &&
4355 (flags
& RENAME_EXCHANGE
))
4358 if ((flags
& RENAME_WHITEOUT
) && !capable(CAP_MKNOD
))
4361 if (flags
& RENAME_EXCHANGE
)
4365 from
= user_path_parent(olddfd
, oldname
,
4366 &old_path
, &old_last
, &old_type
, lookup_flags
);
4368 error
= PTR_ERR(from
);
4372 to
= user_path_parent(newdfd
, newname
,
4373 &new_path
, &new_last
, &new_type
, lookup_flags
);
4375 error
= PTR_ERR(to
);
4380 if (old_path
.mnt
!= new_path
.mnt
)
4384 if (old_type
!= LAST_NORM
)
4387 if (flags
& RENAME_NOREPLACE
)
4389 if (new_type
!= LAST_NORM
)
4392 error
= mnt_want_write(old_path
.mnt
);
4397 trap
= lock_rename(new_path
.dentry
, old_path
.dentry
);
4399 old_dentry
= __lookup_hash(&old_last
, old_path
.dentry
, lookup_flags
);
4400 error
= PTR_ERR(old_dentry
);
4401 if (IS_ERR(old_dentry
))
4403 /* source must exist */
4405 if (d_is_negative(old_dentry
))
4407 new_dentry
= __lookup_hash(&new_last
, new_path
.dentry
, lookup_flags
| target_flags
);
4408 error
= PTR_ERR(new_dentry
);
4409 if (IS_ERR(new_dentry
))
4412 if ((flags
& RENAME_NOREPLACE
) && d_is_positive(new_dentry
))
4414 if (flags
& RENAME_EXCHANGE
) {
4416 if (d_is_negative(new_dentry
))
4419 if (!d_is_dir(new_dentry
)) {
4421 if (new_last
.name
[new_last
.len
])
4425 /* unless the source is a directory trailing slashes give -ENOTDIR */
4426 if (!d_is_dir(old_dentry
)) {
4428 if (old_last
.name
[old_last
.len
])
4430 if (!(flags
& RENAME_EXCHANGE
) && new_last
.name
[new_last
.len
])
4433 /* source should not be ancestor of target */
4435 if (old_dentry
== trap
)
4437 /* target should not be an ancestor of source */
4438 if (!(flags
& RENAME_EXCHANGE
))
4440 if (new_dentry
== trap
)
4443 error
= security_path_rename(&old_path
, old_dentry
,
4444 &new_path
, new_dentry
, flags
);
4447 error
= vfs_rename(old_path
.dentry
->d_inode
, old_dentry
,
4448 new_path
.dentry
->d_inode
, new_dentry
,
4449 &delegated_inode
, flags
);
4455 unlock_rename(new_path
.dentry
, old_path
.dentry
);
4456 if (delegated_inode
) {
4457 error
= break_deleg_wait(&delegated_inode
);
4461 mnt_drop_write(old_path
.mnt
);
4463 if (retry_estale(error
, lookup_flags
))
4464 should_retry
= true;
4465 path_put(&new_path
);
4468 path_put(&old_path
);
4471 should_retry
= false;
4472 lookup_flags
|= LOOKUP_REVAL
;
4479 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
4480 int, newdfd
, const char __user
*, newname
)
4482 return sys_renameat2(olddfd
, oldname
, newdfd
, newname
, 0);
4485 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
4487 return sys_renameat2(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4490 int vfs_whiteout(struct inode
*dir
, struct dentry
*dentry
)
4492 int error
= may_create(dir
, dentry
);
4496 if (!dir
->i_op
->mknod
)
4499 return dir
->i_op
->mknod(dir
, dentry
,
4500 S_IFCHR
| WHITEOUT_MODE
, WHITEOUT_DEV
);
4502 EXPORT_SYMBOL(vfs_whiteout
);
4504 int readlink_copy(char __user
*buffer
, int buflen
, const char *link
)
4506 int len
= PTR_ERR(link
);
4511 if (len
> (unsigned) buflen
)
4513 if (copy_to_user(buffer
, link
, len
))
4518 EXPORT_SYMBOL(readlink_copy
);
4521 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
4522 * have ->get_link() not calling nd_jump_link(). Using (or not using) it
4523 * for any given inode is up to filesystem.
4525 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4527 DEFINE_DELAYED_CALL(done
);
4528 struct inode
*inode
= d_inode(dentry
);
4529 const char *link
= inode
->i_link
;
4533 link
= inode
->i_op
->get_link(dentry
, inode
, &done
);
4535 return PTR_ERR(link
);
4537 res
= readlink_copy(buffer
, buflen
, link
);
4538 do_delayed_call(&done
);
4541 EXPORT_SYMBOL(generic_readlink
);
4543 /* get the link contents into pagecache */
4544 const char *page_get_link(struct dentry
*dentry
, struct inode
*inode
,
4545 struct delayed_call
*callback
)
4549 struct address_space
*mapping
= inode
->i_mapping
;
4552 page
= find_get_page(mapping
, 0);
4554 return ERR_PTR(-ECHILD
);
4555 if (!PageUptodate(page
)) {
4557 return ERR_PTR(-ECHILD
);
4560 page
= read_mapping_page(mapping
, 0, NULL
);
4564 set_delayed_call(callback
, page_put_link
, page
);
4565 BUG_ON(mapping_gfp_mask(mapping
) & __GFP_HIGHMEM
);
4566 kaddr
= page_address(page
);
4567 nd_terminate_link(kaddr
, inode
->i_size
, PAGE_SIZE
- 1);
4571 EXPORT_SYMBOL(page_get_link
);
4573 void page_put_link(void *arg
)
4577 EXPORT_SYMBOL(page_put_link
);
4579 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4581 DEFINE_DELAYED_CALL(done
);
4582 int res
= readlink_copy(buffer
, buflen
,
4583 page_get_link(dentry
, d_inode(dentry
),
4585 do_delayed_call(&done
);
4588 EXPORT_SYMBOL(page_readlink
);
4591 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
4593 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
4595 struct address_space
*mapping
= inode
->i_mapping
;
4599 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
4601 flags
|= AOP_FLAG_NOFS
;
4604 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
4605 flags
, &page
, &fsdata
);
4609 memcpy(page_address(page
), symname
, len
-1);
4611 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
4618 mark_inode_dirty(inode
);
4623 EXPORT_SYMBOL(__page_symlink
);
4625 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
4627 return __page_symlink(inode
, symname
, len
,
4628 !mapping_gfp_constraint(inode
->i_mapping
, __GFP_FS
));
4630 EXPORT_SYMBOL(page_symlink
);
4632 const struct inode_operations page_symlink_inode_operations
= {
4633 .readlink
= generic_readlink
,
4634 .get_link
= page_get_link
,
4636 EXPORT_SYMBOL(page_symlink_inode_operations
);