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 (acl
== ACL_NOT_CACHED
)
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 vfsmount
*mnt
, struct inode
*inode
, int mask
)
378 if (unlikely(!(inode
->i_opflags
& IOP_FASTPERM
))) {
379 if (likely(mnt
&& inode
->i_op
->permission2
))
380 return inode
->i_op
->permission2(mnt
, inode
, mask
);
381 if (likely(inode
->i_op
->permission
))
382 return inode
->i_op
->permission(inode
, mask
);
384 /* This gets set once for the inode lifetime */
385 spin_lock(&inode
->i_lock
);
386 inode
->i_opflags
|= IOP_FASTPERM
;
387 spin_unlock(&inode
->i_lock
);
389 return generic_permission(inode
, mask
);
393 * __inode_permission - Check for access rights to a given inode
394 * @inode: Inode to check permission on
395 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
397 * Check for read/write/execute permissions on an inode.
399 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
401 * This does not check for a read-only file system. You probably want
402 * inode_permission().
404 int __inode_permission2(struct vfsmount
*mnt
, struct inode
*inode
, int mask
)
408 if (unlikely(mask
& MAY_WRITE
)) {
410 * Nobody gets write access to an immutable file.
412 if (IS_IMMUTABLE(inode
))
416 retval
= do_inode_permission(mnt
, inode
, mask
);
420 retval
= devcgroup_inode_permission(inode
, mask
);
424 retval
= security_inode_permission(inode
, mask
);
427 EXPORT_SYMBOL(__inode_permission2
);
429 int __inode_permission(struct inode
*inode
, int mask
)
431 return __inode_permission2(NULL
, inode
, mask
);
433 EXPORT_SYMBOL(__inode_permission
);
436 * sb_permission - Check superblock-level permissions
437 * @sb: Superblock of inode to check permission on
438 * @inode: Inode to check permission on
439 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
441 * Separate out file-system wide checks from inode-specific permission checks.
443 static int sb_permission(struct super_block
*sb
, struct inode
*inode
, int mask
)
445 if (unlikely(mask
& MAY_WRITE
)) {
446 umode_t mode
= inode
->i_mode
;
448 /* Nobody gets write access to a read-only fs. */
449 if ((sb
->s_flags
& MS_RDONLY
) &&
450 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
457 * inode_permission - Check for access rights to a given inode
458 * @inode: Inode to check permission on
459 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
461 * Check for read/write/execute permissions on an inode. We use fs[ug]id for
462 * this, letting us set arbitrary permissions for filesystem access without
463 * changing the "normal" UIDs which are used for other things.
465 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
467 int inode_permission2(struct vfsmount
*mnt
, struct inode
*inode
, int mask
)
471 retval
= sb_permission(inode
->i_sb
, inode
, mask
);
474 return __inode_permission2(mnt
, inode
, mask
);
476 EXPORT_SYMBOL(inode_permission2
);
478 int inode_permission(struct inode
*inode
, int mask
)
480 return inode_permission2(NULL
, inode
, mask
);
482 EXPORT_SYMBOL(inode_permission
);
485 * path_get - get a reference to a path
486 * @path: path to get the reference to
488 * Given a path increment the reference count to the dentry and the vfsmount.
490 void path_get(const struct path
*path
)
495 EXPORT_SYMBOL(path_get
);
498 * path_put - put a reference to a path
499 * @path: path to put the reference to
501 * Given a path decrement the reference count to the dentry and the vfsmount.
503 void path_put(const struct path
*path
)
508 EXPORT_SYMBOL(path_put
);
510 #define EMBEDDED_LEVELS 2
515 struct inode
*inode
; /* path.dentry.d_inode */
520 int total_link_count
;
527 } *stack
, internal
[EMBEDDED_LEVELS
];
528 struct filename
*name
;
529 struct nameidata
*saved
;
534 static void set_nameidata(struct nameidata
*p
, int dfd
, struct filename
*name
)
536 struct nameidata
*old
= current
->nameidata
;
537 p
->stack
= p
->internal
;
540 p
->total_link_count
= old
? old
->total_link_count
: 0;
542 current
->nameidata
= p
;
545 static void restore_nameidata(void)
547 struct nameidata
*now
= current
->nameidata
, *old
= now
->saved
;
549 current
->nameidata
= old
;
551 old
->total_link_count
= now
->total_link_count
;
552 if (now
->stack
!= now
->internal
) {
554 now
->stack
= now
->internal
;
558 static int __nd_alloc_stack(struct nameidata
*nd
)
562 if (nd
->flags
& LOOKUP_RCU
) {
563 p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
568 p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
573 memcpy(p
, nd
->internal
, sizeof(nd
->internal
));
579 * path_connected - Verify that a path->dentry is below path->mnt.mnt_root
580 * @path: nameidate to verify
582 * Rename can sometimes move a file or directory outside of a bind
583 * mount, path_connected allows those cases to be detected.
585 static bool path_connected(const struct path
*path
)
587 struct vfsmount
*mnt
= path
->mnt
;
589 /* Only bind mounts can have disconnected paths */
590 if (mnt
->mnt_root
== mnt
->mnt_sb
->s_root
)
593 return is_subdir(path
->dentry
, mnt
->mnt_root
);
596 static inline int nd_alloc_stack(struct nameidata
*nd
)
598 if (likely(nd
->depth
!= EMBEDDED_LEVELS
))
600 if (likely(nd
->stack
!= nd
->internal
))
602 return __nd_alloc_stack(nd
);
605 static void drop_links(struct nameidata
*nd
)
609 struct saved
*last
= nd
->stack
+ i
;
610 struct inode
*inode
= last
->inode
;
611 if (last
->cookie
&& inode
->i_op
->put_link
) {
612 inode
->i_op
->put_link(inode
, last
->cookie
);
618 static void terminate_walk(struct nameidata
*nd
)
621 if (!(nd
->flags
& LOOKUP_RCU
)) {
624 for (i
= 0; i
< nd
->depth
; i
++)
625 path_put(&nd
->stack
[i
].link
);
626 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
631 nd
->flags
&= ~LOOKUP_RCU
;
632 if (!(nd
->flags
& LOOKUP_ROOT
))
639 /* path_put is needed afterwards regardless of success or failure */
640 static bool legitimize_path(struct nameidata
*nd
,
641 struct path
*path
, unsigned seq
)
643 int res
= __legitimize_mnt(path
->mnt
, nd
->m_seq
);
650 if (unlikely(!lockref_get_not_dead(&path
->dentry
->d_lockref
))) {
654 return !read_seqcount_retry(&path
->dentry
->d_seq
, seq
);
657 static bool legitimize_links(struct nameidata
*nd
)
660 for (i
= 0; i
< nd
->depth
; i
++) {
661 struct saved
*last
= nd
->stack
+ i
;
662 if (unlikely(!legitimize_path(nd
, &last
->link
, last
->seq
))) {
672 * Path walking has 2 modes, rcu-walk and ref-walk (see
673 * Documentation/filesystems/path-lookup.txt). In situations when we can't
674 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
675 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
676 * mode. Refcounts are grabbed at the last known good point before rcu-walk
677 * got stuck, so ref-walk may continue from there. If this is not successful
678 * (eg. a seqcount has changed), then failure is returned and it's up to caller
679 * to restart the path walk from the beginning in ref-walk mode.
683 * unlazy_walk - try to switch to ref-walk mode.
684 * @nd: nameidata pathwalk data
685 * @dentry: child of nd->path.dentry or NULL
686 * @seq: seq number to check dentry against
687 * Returns: 0 on success, -ECHILD on failure
689 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
690 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
691 * @nd or NULL. Must be called from rcu-walk context.
692 * Nothing should touch nameidata between unlazy_walk() failure and
695 static int unlazy_walk(struct nameidata
*nd
, struct dentry
*dentry
, unsigned seq
)
697 struct dentry
*parent
= nd
->path
.dentry
;
699 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
701 nd
->flags
&= ~LOOKUP_RCU
;
702 if (unlikely(!legitimize_links(nd
)))
704 if (unlikely(!legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
)))
706 if (unlikely(!lockref_get_not_dead(&parent
->d_lockref
)))
710 * For a negative lookup, the lookup sequence point is the parents
711 * sequence point, and it only needs to revalidate the parent dentry.
713 * For a positive lookup, we need to move both the parent and the
714 * dentry from the RCU domain to be properly refcounted. And the
715 * sequence number in the dentry validates *both* dentry counters,
716 * since we checked the sequence number of the parent after we got
717 * the child sequence number. So we know the parent must still
718 * be valid if the child sequence number is still valid.
721 if (read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
723 BUG_ON(nd
->inode
!= parent
->d_inode
);
725 if (!lockref_get_not_dead(&dentry
->d_lockref
))
727 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
732 * Sequence counts matched. Now make sure that the root is
733 * still valid and get it if required.
735 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
736 if (unlikely(!legitimize_path(nd
, &nd
->root
, nd
->root_seq
))) {
753 nd
->path
.dentry
= NULL
;
757 if (!(nd
->flags
& LOOKUP_ROOT
))
762 static int unlazy_link(struct nameidata
*nd
, struct path
*link
, unsigned seq
)
764 if (unlikely(!legitimize_path(nd
, link
, seq
))) {
767 nd
->flags
&= ~LOOKUP_RCU
;
769 nd
->path
.dentry
= NULL
;
770 if (!(nd
->flags
& LOOKUP_ROOT
))
773 } else if (likely(unlazy_walk(nd
, NULL
, 0)) == 0) {
780 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
782 return dentry
->d_op
->d_revalidate(dentry
, flags
);
786 * complete_walk - successful completion of path walk
787 * @nd: pointer nameidata
789 * If we had been in RCU mode, drop out of it and legitimize nd->path.
790 * Revalidate the final result, unless we'd already done that during
791 * the path walk or the filesystem doesn't ask for it. Return 0 on
792 * success, -error on failure. In case of failure caller does not
793 * need to drop nd->path.
795 static int complete_walk(struct nameidata
*nd
)
797 struct dentry
*dentry
= nd
->path
.dentry
;
800 if (nd
->flags
& LOOKUP_RCU
) {
801 if (!(nd
->flags
& LOOKUP_ROOT
))
803 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
807 if (likely(!(nd
->flags
& LOOKUP_JUMPED
)))
810 if (likely(!(dentry
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)))
813 status
= dentry
->d_op
->d_weak_revalidate(dentry
, nd
->flags
);
823 static void set_root(struct nameidata
*nd
)
825 get_fs_root(current
->fs
, &nd
->root
);
828 static void set_root_rcu(struct nameidata
*nd
)
830 struct fs_struct
*fs
= current
->fs
;
834 seq
= read_seqcount_begin(&fs
->seq
);
836 nd
->root_seq
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
837 } while (read_seqcount_retry(&fs
->seq
, seq
));
840 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
843 if (path
->mnt
!= nd
->path
.mnt
)
847 static inline void path_to_nameidata(const struct path
*path
,
848 struct nameidata
*nd
)
850 if (!(nd
->flags
& LOOKUP_RCU
)) {
851 dput(nd
->path
.dentry
);
852 if (nd
->path
.mnt
!= path
->mnt
)
853 mntput(nd
->path
.mnt
);
855 nd
->path
.mnt
= path
->mnt
;
856 nd
->path
.dentry
= path
->dentry
;
860 * Helper to directly jump to a known parsed path from ->follow_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 struct inode
*inode
= last
->inode
;
877 if (last
->cookie
&& inode
->i_op
->put_link
)
878 inode
->i_op
->put_link(inode
, last
->cookie
);
879 if (!(nd
->flags
& LOOKUP_RCU
))
880 path_put(&last
->link
);
883 int sysctl_protected_symlinks __read_mostly
= 0;
884 int sysctl_protected_hardlinks __read_mostly
= 0;
887 * may_follow_link - Check symlink following for unsafe situations
888 * @nd: nameidata pathwalk data
890 * In the case of the sysctl_protected_symlinks sysctl being enabled,
891 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
892 * in a sticky world-writable directory. This is to protect privileged
893 * processes from failing races against path names that may change out
894 * from under them by way of other users creating malicious symlinks.
895 * It will permit symlinks to be followed only when outside a sticky
896 * world-writable directory, or when the uid of the symlink and follower
897 * match, or when the directory owner matches the symlink's owner.
899 * Returns 0 if following the symlink is allowed, -ve on error.
901 static inline int may_follow_link(struct nameidata
*nd
)
903 const struct inode
*inode
;
904 const struct inode
*parent
;
907 if (!sysctl_protected_symlinks
)
910 /* Allowed if owner and follower match. */
911 inode
= nd
->stack
[0].inode
;
912 if (uid_eq(current_cred()->fsuid
, inode
->i_uid
))
915 /* Allowed if parent directory not sticky and world-writable. */
917 if ((parent
->i_mode
& (S_ISVTX
|S_IWOTH
)) != (S_ISVTX
|S_IWOTH
))
920 /* Allowed if parent directory and link owner match. */
921 puid
= parent
->i_uid
;
922 if (uid_valid(puid
) && uid_eq(puid
, inode
->i_uid
))
925 if (nd
->flags
& LOOKUP_RCU
)
928 audit_log_link_denied("follow_link", &nd
->stack
[0].link
);
933 * safe_hardlink_source - Check for safe hardlink conditions
934 * @inode: the source inode to hardlink from
936 * Return false if at least one of the following conditions:
937 * - inode is not a regular file
939 * - inode is setgid and group-exec
940 * - access failure for read and write
942 * Otherwise returns true.
944 static bool safe_hardlink_source(struct inode
*inode
)
946 umode_t mode
= inode
->i_mode
;
948 /* Special files should not get pinned to the filesystem. */
952 /* Setuid files should not get pinned to the filesystem. */
956 /* Executable setgid files should not get pinned to the filesystem. */
957 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
))
960 /* Hardlinking to unreadable or unwritable sources is dangerous. */
961 if (inode_permission(inode
, MAY_READ
| MAY_WRITE
))
968 * may_linkat - Check permissions for creating a hardlink
969 * @link: the source to hardlink from
971 * Block hardlink when all of:
972 * - sysctl_protected_hardlinks enabled
973 * - fsuid does not match inode
974 * - hardlink source is unsafe (see safe_hardlink_source() above)
975 * - not CAP_FOWNER in a namespace with the inode owner uid mapped
977 * Returns 0 if successful, -ve on error.
979 static int may_linkat(struct path
*link
)
983 if (!sysctl_protected_hardlinks
)
986 inode
= link
->dentry
->d_inode
;
988 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
989 * otherwise, it must be a safe source.
991 if (inode_owner_or_capable(inode
) || safe_hardlink_source(inode
))
994 audit_log_link_denied("linkat", link
);
998 static __always_inline
999 const char *get_link(struct nameidata
*nd
)
1001 struct saved
*last
= nd
->stack
+ nd
->depth
- 1;
1002 struct dentry
*dentry
= last
->link
.dentry
;
1003 struct inode
*inode
= last
->inode
;
1007 if (!(nd
->flags
& LOOKUP_RCU
)) {
1008 touch_atime(&last
->link
);
1010 } else if (atime_needs_update(&last
->link
, inode
)) {
1011 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
1012 return ERR_PTR(-ECHILD
);
1013 touch_atime(&last
->link
);
1016 error
= security_inode_follow_link(dentry
, inode
,
1017 nd
->flags
& LOOKUP_RCU
);
1018 if (unlikely(error
))
1019 return ERR_PTR(error
);
1021 nd
->last_type
= LAST_BIND
;
1022 res
= inode
->i_link
;
1024 if (nd
->flags
& LOOKUP_RCU
) {
1025 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
1026 return ERR_PTR(-ECHILD
);
1028 res
= inode
->i_op
->follow_link(dentry
, &last
->cookie
);
1029 if (IS_ERR_OR_NULL(res
)) {
1030 last
->cookie
= NULL
;
1035 if (nd
->flags
& LOOKUP_RCU
) {
1039 nd
->path
= nd
->root
;
1040 d
= nd
->path
.dentry
;
1041 nd
->inode
= d
->d_inode
;
1042 nd
->seq
= nd
->root_seq
;
1043 if (unlikely(read_seqcount_retry(&d
->d_seq
, nd
->seq
)))
1044 return ERR_PTR(-ECHILD
);
1048 path_put(&nd
->path
);
1049 nd
->path
= nd
->root
;
1050 path_get(&nd
->root
);
1051 nd
->inode
= nd
->path
.dentry
->d_inode
;
1053 nd
->flags
|= LOOKUP_JUMPED
;
1054 while (unlikely(*++res
== '/'))
1063 * follow_up - Find the mountpoint of path's vfsmount
1065 * Given a path, find the mountpoint of its source file system.
1066 * Replace @path with the path of the mountpoint in the parent mount.
1069 * Return 1 if we went up a level and 0 if we were already at the
1072 int follow_up(struct path
*path
)
1074 struct mount
*mnt
= real_mount(path
->mnt
);
1075 struct mount
*parent
;
1076 struct dentry
*mountpoint
;
1078 read_seqlock_excl(&mount_lock
);
1079 parent
= mnt
->mnt_parent
;
1080 if (parent
== mnt
) {
1081 read_sequnlock_excl(&mount_lock
);
1084 mntget(&parent
->mnt
);
1085 mountpoint
= dget(mnt
->mnt_mountpoint
);
1086 read_sequnlock_excl(&mount_lock
);
1088 path
->dentry
= mountpoint
;
1090 path
->mnt
= &parent
->mnt
;
1093 EXPORT_SYMBOL(follow_up
);
1096 * Perform an automount
1097 * - return -EISDIR to tell follow_managed() to stop and return the path we
1100 static int follow_automount(struct path
*path
, struct nameidata
*nd
,
1103 struct vfsmount
*mnt
;
1106 if (!path
->dentry
->d_op
|| !path
->dentry
->d_op
->d_automount
)
1109 /* We don't want to mount if someone's just doing a stat -
1110 * unless they're stat'ing a directory and appended a '/' to
1113 * We do, however, want to mount if someone wants to open or
1114 * create a file of any type under the mountpoint, wants to
1115 * traverse through the mountpoint or wants to open the
1116 * mounted directory. Also, autofs may mark negative dentries
1117 * as being automount points. These will need the attentions
1118 * of the daemon to instantiate them before they can be used.
1120 if (!(nd
->flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
1121 LOOKUP_OPEN
| LOOKUP_CREATE
| LOOKUP_AUTOMOUNT
)) &&
1122 path
->dentry
->d_inode
)
1125 nd
->total_link_count
++;
1126 if (nd
->total_link_count
>= 40)
1129 mnt
= path
->dentry
->d_op
->d_automount(path
);
1132 * The filesystem is allowed to return -EISDIR here to indicate
1133 * it doesn't want to automount. For instance, autofs would do
1134 * this so that its userspace daemon can mount on this dentry.
1136 * However, we can only permit this if it's a terminal point in
1137 * the path being looked up; if it wasn't then the remainder of
1138 * the path is inaccessible and we should say so.
1140 if (PTR_ERR(mnt
) == -EISDIR
&& (nd
->flags
& LOOKUP_PARENT
))
1142 return PTR_ERR(mnt
);
1145 if (!mnt
) /* mount collision */
1148 if (!*need_mntput
) {
1149 /* lock_mount() may release path->mnt on error */
1151 *need_mntput
= true;
1153 err
= finish_automount(mnt
, path
);
1157 /* Someone else made a mount here whilst we were busy */
1162 path
->dentry
= dget(mnt
->mnt_root
);
1171 * Handle a dentry that is managed in some way.
1172 * - Flagged for transit management (autofs)
1173 * - Flagged as mountpoint
1174 * - Flagged as automount point
1176 * This may only be called in refwalk mode.
1178 * Serialization is taken care of in namespace.c
1180 static int follow_managed(struct path
*path
, struct nameidata
*nd
)
1182 struct vfsmount
*mnt
= path
->mnt
; /* held by caller, must be left alone */
1184 bool need_mntput
= false;
1187 /* Given that we're not holding a lock here, we retain the value in a
1188 * local variable for each dentry as we look at it so that we don't see
1189 * the components of that value change under us */
1190 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1191 managed
&= DCACHE_MANAGED_DENTRY
,
1192 unlikely(managed
!= 0)) {
1193 /* Allow the filesystem to manage the transit without i_mutex
1195 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1196 BUG_ON(!path
->dentry
->d_op
);
1197 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1198 ret
= path
->dentry
->d_op
->d_manage(path
->dentry
, false);
1203 /* Transit to a mounted filesystem. */
1204 if (managed
& DCACHE_MOUNTED
) {
1205 struct vfsmount
*mounted
= lookup_mnt(path
);
1210 path
->mnt
= mounted
;
1211 path
->dentry
= dget(mounted
->mnt_root
);
1216 /* Something is mounted on this dentry in another
1217 * namespace and/or whatever was mounted there in this
1218 * namespace got unmounted before lookup_mnt() could
1222 /* Handle an automount point */
1223 if (managed
& DCACHE_NEED_AUTOMOUNT
) {
1224 ret
= follow_automount(path
, nd
, &need_mntput
);
1230 /* We didn't change the current path point */
1234 if (need_mntput
&& path
->mnt
== mnt
)
1239 nd
->flags
|= LOOKUP_JUMPED
;
1240 if (unlikely(ret
< 0))
1241 path_put_conditional(path
, nd
);
1245 int follow_down_one(struct path
*path
)
1247 struct vfsmount
*mounted
;
1249 mounted
= lookup_mnt(path
);
1253 path
->mnt
= mounted
;
1254 path
->dentry
= dget(mounted
->mnt_root
);
1259 EXPORT_SYMBOL(follow_down_one
);
1261 static inline int managed_dentry_rcu(struct dentry
*dentry
)
1263 return (dentry
->d_flags
& DCACHE_MANAGE_TRANSIT
) ?
1264 dentry
->d_op
->d_manage(dentry
, true) : 0;
1268 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1269 * we meet a managed dentry that would need blocking.
1271 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
,
1272 struct inode
**inode
, unsigned *seqp
)
1275 struct mount
*mounted
;
1277 * Don't forget we might have a non-mountpoint managed dentry
1278 * that wants to block transit.
1280 switch (managed_dentry_rcu(path
->dentry
)) {
1290 if (!d_mountpoint(path
->dentry
))
1291 return !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1293 mounted
= __lookup_mnt(path
->mnt
, path
->dentry
);
1296 path
->mnt
= &mounted
->mnt
;
1297 path
->dentry
= mounted
->mnt
.mnt_root
;
1298 nd
->flags
|= LOOKUP_JUMPED
;
1299 *seqp
= read_seqcount_begin(&path
->dentry
->d_seq
);
1301 * Update the inode too. We don't need to re-check the
1302 * dentry sequence number here after this d_inode read,
1303 * because a mount-point is always pinned.
1305 *inode
= path
->dentry
->d_inode
;
1307 return !read_seqretry(&mount_lock
, nd
->m_seq
) &&
1308 !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1311 static int follow_dotdot_rcu(struct nameidata
*nd
)
1313 struct inode
*inode
= nd
->inode
;
1318 if (path_equal(&nd
->path
, &nd
->root
))
1320 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1321 struct dentry
*old
= nd
->path
.dentry
;
1322 struct dentry
*parent
= old
->d_parent
;
1325 inode
= parent
->d_inode
;
1326 seq
= read_seqcount_begin(&parent
->d_seq
);
1327 if (unlikely(read_seqcount_retry(&old
->d_seq
, nd
->seq
)))
1329 nd
->path
.dentry
= parent
;
1331 if (unlikely(!path_connected(&nd
->path
)))
1335 struct mount
*mnt
= real_mount(nd
->path
.mnt
);
1336 struct mount
*mparent
= mnt
->mnt_parent
;
1337 struct dentry
*mountpoint
= mnt
->mnt_mountpoint
;
1338 struct inode
*inode2
= mountpoint
->d_inode
;
1339 unsigned seq
= read_seqcount_begin(&mountpoint
->d_seq
);
1340 if (unlikely(read_seqretry(&mount_lock
, nd
->m_seq
)))
1342 if (&mparent
->mnt
== nd
->path
.mnt
)
1344 /* we know that mountpoint was pinned */
1345 nd
->path
.dentry
= mountpoint
;
1346 nd
->path
.mnt
= &mparent
->mnt
;
1351 while (unlikely(d_mountpoint(nd
->path
.dentry
))) {
1352 struct mount
*mounted
;
1353 mounted
= __lookup_mnt(nd
->path
.mnt
, nd
->path
.dentry
);
1354 if (unlikely(read_seqretry(&mount_lock
, nd
->m_seq
)))
1358 nd
->path
.mnt
= &mounted
->mnt
;
1359 nd
->path
.dentry
= mounted
->mnt
.mnt_root
;
1360 inode
= nd
->path
.dentry
->d_inode
;
1361 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1368 * Follow down to the covering mount currently visible to userspace. At each
1369 * point, the filesystem owning that dentry may be queried as to whether the
1370 * caller is permitted to proceed or not.
1372 int follow_down(struct path
*path
)
1377 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1378 unlikely(managed
& DCACHE_MANAGED_DENTRY
)) {
1379 /* Allow the filesystem to manage the transit without i_mutex
1382 * We indicate to the filesystem if someone is trying to mount
1383 * something here. This gives autofs the chance to deny anyone
1384 * other than its daemon the right to mount on its
1387 * The filesystem may sleep at this point.
1389 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1390 BUG_ON(!path
->dentry
->d_op
);
1391 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1392 ret
= path
->dentry
->d_op
->d_manage(
1393 path
->dentry
, false);
1395 return ret
== -EISDIR
? 0 : ret
;
1398 /* Transit to a mounted filesystem. */
1399 if (managed
& DCACHE_MOUNTED
) {
1400 struct vfsmount
*mounted
= lookup_mnt(path
);
1405 path
->mnt
= mounted
;
1406 path
->dentry
= dget(mounted
->mnt_root
);
1410 /* Don't handle automount points here */
1415 EXPORT_SYMBOL(follow_down
);
1418 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1420 static void follow_mount(struct path
*path
)
1422 while (d_mountpoint(path
->dentry
)) {
1423 struct vfsmount
*mounted
= lookup_mnt(path
);
1428 path
->mnt
= mounted
;
1429 path
->dentry
= dget(mounted
->mnt_root
);
1433 static int follow_dotdot(struct nameidata
*nd
)
1439 struct dentry
*old
= nd
->path
.dentry
;
1441 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1442 nd
->path
.mnt
== nd
->root
.mnt
) {
1445 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1446 /* rare case of legitimate dget_parent()... */
1447 nd
->path
.dentry
= dget_parent(nd
->path
.dentry
);
1449 if (unlikely(!path_connected(&nd
->path
)))
1453 if (!follow_up(&nd
->path
))
1456 follow_mount(&nd
->path
);
1457 nd
->inode
= nd
->path
.dentry
->d_inode
;
1462 * This looks up the name in dcache, possibly revalidates the old dentry and
1463 * allocates a new one if not found or not valid. In the need_lookup argument
1464 * returns whether i_op->lookup is necessary.
1466 * dir->d_inode->i_mutex must be held
1468 static struct dentry
*lookup_dcache(struct qstr
*name
, struct dentry
*dir
,
1469 unsigned int flags
, bool *need_lookup
)
1471 struct dentry
*dentry
;
1474 *need_lookup
= false;
1475 dentry
= d_lookup(dir
, name
);
1477 if (dentry
->d_flags
& DCACHE_OP_REVALIDATE
) {
1478 error
= d_revalidate(dentry
, flags
);
1479 if (unlikely(error
<= 0)) {
1482 return ERR_PTR(error
);
1484 d_invalidate(dentry
);
1493 dentry
= d_alloc(dir
, name
);
1494 if (unlikely(!dentry
))
1495 return ERR_PTR(-ENOMEM
);
1497 *need_lookup
= true;
1503 * Call i_op->lookup on the dentry. The dentry must be negative and
1506 * dir->d_inode->i_mutex must be held
1508 static struct dentry
*lookup_real(struct inode
*dir
, struct dentry
*dentry
,
1513 /* Don't create child dentry for a dead directory. */
1514 if (unlikely(IS_DEADDIR(dir
))) {
1516 return ERR_PTR(-ENOENT
);
1519 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1520 if (unlikely(old
)) {
1527 static struct dentry
*__lookup_hash(struct qstr
*name
,
1528 struct dentry
*base
, unsigned int flags
)
1531 struct dentry
*dentry
;
1533 dentry
= lookup_dcache(name
, base
, flags
, &need_lookup
);
1537 return lookup_real(base
->d_inode
, dentry
, flags
);
1541 * It's more convoluted than I'd like it to be, but... it's still fairly
1542 * small and for now I'd prefer to have fast path as straight as possible.
1543 * It _is_ time-critical.
1545 static int lookup_fast(struct nameidata
*nd
,
1546 struct path
*path
, struct inode
**inode
,
1549 struct vfsmount
*mnt
= nd
->path
.mnt
;
1550 struct dentry
*dentry
, *parent
= nd
->path
.dentry
;
1556 * Rename seqlock is not required here because in the off chance
1557 * of a false negative due to a concurrent rename, we're going to
1558 * do the non-racy lookup, below.
1560 if (nd
->flags
& LOOKUP_RCU
) {
1563 dentry
= __d_lookup_rcu(parent
, &nd
->last
, &seq
);
1568 * This sequence count validates that the inode matches
1569 * the dentry name information from lookup.
1571 *inode
= d_backing_inode(dentry
);
1572 negative
= d_is_negative(dentry
);
1573 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
1577 * This sequence count validates that the parent had no
1578 * changes while we did the lookup of the dentry above.
1580 * The memory barrier in read_seqcount_begin of child is
1581 * enough, we can use __read_seqcount_retry here.
1583 if (__read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
1587 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
)) {
1588 status
= d_revalidate(dentry
, nd
->flags
);
1589 if (unlikely(status
<= 0)) {
1590 if (status
!= -ECHILD
)
1596 * Note: do negative dentry check after revalidation in
1597 * case that drops it.
1602 path
->dentry
= dentry
;
1603 if (likely(__follow_mount_rcu(nd
, path
, inode
, seqp
)))
1606 if (unlazy_walk(nd
, dentry
, seq
))
1609 dentry
= __d_lookup(parent
, &nd
->last
);
1612 if (unlikely(!dentry
))
1615 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
) && need_reval
)
1616 status
= d_revalidate(dentry
, nd
->flags
);
1617 if (unlikely(status
<= 0)) {
1622 d_invalidate(dentry
);
1627 if (unlikely(d_is_negative(dentry
))) {
1632 path
->dentry
= dentry
;
1633 err
= follow_managed(path
, nd
);
1635 *inode
= d_backing_inode(path
->dentry
);
1642 /* Fast lookup failed, do it the slow way */
1643 static int lookup_slow(struct nameidata
*nd
, struct path
*path
)
1645 struct dentry
*dentry
, *parent
;
1647 parent
= nd
->path
.dentry
;
1648 BUG_ON(nd
->inode
!= parent
->d_inode
);
1650 mutex_lock(&parent
->d_inode
->i_mutex
);
1651 dentry
= __lookup_hash(&nd
->last
, parent
, nd
->flags
);
1652 mutex_unlock(&parent
->d_inode
->i_mutex
);
1654 return PTR_ERR(dentry
);
1655 path
->mnt
= nd
->path
.mnt
;
1656 path
->dentry
= dentry
;
1657 return follow_managed(path
, nd
);
1660 static inline int may_lookup(struct nameidata
*nd
)
1662 if (nd
->flags
& LOOKUP_RCU
) {
1663 int err
= inode_permission2(nd
->path
.mnt
, nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1666 if (unlazy_walk(nd
, NULL
, 0))
1669 return inode_permission2(nd
->path
.mnt
, nd
->inode
, MAY_EXEC
);
1672 static inline int handle_dots(struct nameidata
*nd
, int type
)
1674 if (type
== LAST_DOTDOT
) {
1675 if (nd
->flags
& LOOKUP_RCU
) {
1676 return follow_dotdot_rcu(nd
);
1678 return follow_dotdot(nd
);
1683 static int pick_link(struct nameidata
*nd
, struct path
*link
,
1684 struct inode
*inode
, unsigned seq
)
1688 if (unlikely(nd
->total_link_count
++ >= MAXSYMLINKS
)) {
1689 path_to_nameidata(link
, nd
);
1692 if (!(nd
->flags
& LOOKUP_RCU
)) {
1693 if (link
->mnt
== nd
->path
.mnt
)
1696 error
= nd_alloc_stack(nd
);
1697 if (unlikely(error
)) {
1698 if (error
== -ECHILD
) {
1699 if (unlikely(unlazy_link(nd
, link
, seq
)))
1701 error
= nd_alloc_stack(nd
);
1709 last
= nd
->stack
+ nd
->depth
++;
1711 last
->cookie
= NULL
;
1712 last
->inode
= inode
;
1718 * Do we need to follow links? We _really_ want to be able
1719 * to do this check without having to look at inode->i_op,
1720 * so we keep a cache of "no, this doesn't need follow_link"
1721 * for the common case.
1723 static inline int should_follow_link(struct nameidata
*nd
, struct path
*link
,
1725 struct inode
*inode
, unsigned seq
)
1727 if (likely(!d_is_symlink(link
->dentry
)))
1731 /* make sure that d_is_symlink above matches inode */
1732 if (nd
->flags
& LOOKUP_RCU
) {
1733 if (read_seqcount_retry(&link
->dentry
->d_seq
, seq
))
1736 return pick_link(nd
, link
, inode
, seq
);
1739 enum {WALK_GET
= 1, WALK_PUT
= 2};
1741 static int walk_component(struct nameidata
*nd
, int flags
)
1744 struct inode
*inode
;
1748 * "." and ".." are special - ".." especially so because it has
1749 * to be able to know about the current root directory and
1750 * parent relationships.
1752 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
1753 err
= handle_dots(nd
, nd
->last_type
);
1754 if (flags
& WALK_PUT
)
1758 err
= lookup_fast(nd
, &path
, &inode
, &seq
);
1759 if (unlikely(err
)) {
1763 err
= lookup_slow(nd
, &path
);
1767 seq
= 0; /* we are already out of RCU mode */
1769 if (d_is_negative(path
.dentry
))
1771 inode
= d_backing_inode(path
.dentry
);
1774 if (flags
& WALK_PUT
)
1776 err
= should_follow_link(nd
, &path
, flags
& WALK_GET
, inode
, seq
);
1779 path_to_nameidata(&path
, nd
);
1785 path_to_nameidata(&path
, nd
);
1790 * We can do the critical dentry name comparison and hashing
1791 * operations one word at a time, but we are limited to:
1793 * - Architectures with fast unaligned word accesses. We could
1794 * do a "get_unaligned()" if this helps and is sufficiently
1797 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1798 * do not trap on the (extremely unlikely) case of a page
1799 * crossing operation.
1801 * - Furthermore, we need an efficient 64-bit compile for the
1802 * 64-bit case in order to generate the "number of bytes in
1803 * the final mask". Again, that could be replaced with a
1804 * efficient population count instruction or similar.
1806 #ifdef CONFIG_DCACHE_WORD_ACCESS
1808 #include <asm/word-at-a-time.h>
1812 static inline unsigned int fold_hash(unsigned long hash
)
1814 return hash_64(hash
, 32);
1817 #else /* 32-bit case */
1819 #define fold_hash(x) (x)
1823 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1825 unsigned long a
, mask
;
1826 unsigned long hash
= 0;
1829 a
= load_unaligned_zeropad(name
);
1830 if (len
< sizeof(unsigned long))
1834 name
+= sizeof(unsigned long);
1835 len
-= sizeof(unsigned long);
1839 mask
= bytemask_from_count(len
);
1842 return fold_hash(hash
);
1844 EXPORT_SYMBOL(full_name_hash
);
1847 * Calculate the length and hash of the path component, and
1848 * return the "hash_len" as the result.
1850 static inline u64
hash_name(const char *name
)
1852 unsigned long a
, b
, adata
, bdata
, mask
, hash
, len
;
1853 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
1856 len
= -sizeof(unsigned long);
1858 hash
= (hash
+ a
) * 9;
1859 len
+= sizeof(unsigned long);
1860 a
= load_unaligned_zeropad(name
+len
);
1861 b
= a
^ REPEAT_BYTE('/');
1862 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
1864 adata
= prep_zero_mask(a
, adata
, &constants
);
1865 bdata
= prep_zero_mask(b
, bdata
, &constants
);
1867 mask
= create_zero_mask(adata
| bdata
);
1869 hash
+= a
& zero_bytemask(mask
);
1870 len
+= find_zero(mask
);
1871 return hashlen_create(fold_hash(hash
), len
);
1876 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1878 unsigned long hash
= init_name_hash();
1880 hash
= partial_name_hash(*name
++, hash
);
1881 return end_name_hash(hash
);
1883 EXPORT_SYMBOL(full_name_hash
);
1886 * We know there's a real path component here of at least
1889 static inline u64
hash_name(const char *name
)
1891 unsigned long hash
= init_name_hash();
1892 unsigned long len
= 0, c
;
1894 c
= (unsigned char)*name
;
1897 hash
= partial_name_hash(c
, hash
);
1898 c
= (unsigned char)name
[len
];
1899 } while (c
&& c
!= '/');
1900 return hashlen_create(end_name_hash(hash
), len
);
1907 * This is the basic name resolution function, turning a pathname into
1908 * the final dentry. We expect 'base' to be positive and a directory.
1910 * Returns 0 and nd will have valid dentry and mnt on success.
1911 * Returns error and drops reference to input namei data on failure.
1913 static int link_path_walk(const char *name
, struct nameidata
*nd
)
1922 /* At this point we know we have a real path component. */
1927 err
= may_lookup(nd
);
1931 hash_len
= hash_name(name
);
1934 if (name
[0] == '.') switch (hashlen_len(hash_len
)) {
1936 if (name
[1] == '.') {
1938 nd
->flags
|= LOOKUP_JUMPED
;
1944 if (likely(type
== LAST_NORM
)) {
1945 struct dentry
*parent
= nd
->path
.dentry
;
1946 nd
->flags
&= ~LOOKUP_JUMPED
;
1947 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
1948 struct qstr
this = { { .hash_len
= hash_len
}, .name
= name
};
1949 err
= parent
->d_op
->d_hash(parent
, &this);
1952 hash_len
= this.hash_len
;
1957 nd
->last
.hash_len
= hash_len
;
1958 nd
->last
.name
= name
;
1959 nd
->last_type
= type
;
1961 name
+= hashlen_len(hash_len
);
1965 * If it wasn't NUL, we know it was '/'. Skip that
1966 * slash, and continue until no more slashes.
1970 } while (unlikely(*name
== '/'));
1971 if (unlikely(!*name
)) {
1973 /* pathname body, done */
1976 name
= nd
->stack
[nd
->depth
- 1].name
;
1977 /* trailing symlink, done */
1980 /* last component of nested symlink */
1981 err
= walk_component(nd
, WALK_GET
| WALK_PUT
);
1983 err
= walk_component(nd
, WALK_GET
);
1989 const char *s
= get_link(nd
);
1998 nd
->stack
[nd
->depth
- 1].name
= name
;
2003 if (unlikely(!d_can_lookup(nd
->path
.dentry
))) {
2004 if (nd
->flags
& LOOKUP_RCU
) {
2005 if (unlazy_walk(nd
, NULL
, 0))
2013 static const char *path_init(struct nameidata
*nd
, unsigned flags
)
2016 const char *s
= nd
->name
->name
;
2018 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
2019 nd
->flags
= flags
| LOOKUP_JUMPED
| LOOKUP_PARENT
;
2021 if (flags
& LOOKUP_ROOT
) {
2022 struct dentry
*root
= nd
->root
.dentry
;
2023 struct vfsmount
*mnt
= nd
->root
.mnt
;
2024 struct inode
*inode
= root
->d_inode
;
2026 if (!d_can_lookup(root
))
2027 return ERR_PTR(-ENOTDIR
);
2028 retval
= inode_permission2(mnt
, inode
, MAY_EXEC
);
2030 return ERR_PTR(retval
);
2032 nd
->path
= nd
->root
;
2034 if (flags
& LOOKUP_RCU
) {
2036 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2037 nd
->root_seq
= nd
->seq
;
2038 nd
->m_seq
= read_seqbegin(&mount_lock
);
2040 path_get(&nd
->path
);
2045 nd
->root
.mnt
= NULL
;
2047 nd
->m_seq
= read_seqbegin(&mount_lock
);
2049 if (flags
& LOOKUP_RCU
) {
2052 nd
->seq
= nd
->root_seq
;
2055 path_get(&nd
->root
);
2057 nd
->path
= nd
->root
;
2058 } else if (nd
->dfd
== AT_FDCWD
) {
2059 if (flags
& LOOKUP_RCU
) {
2060 struct fs_struct
*fs
= current
->fs
;
2066 seq
= read_seqcount_begin(&fs
->seq
);
2068 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2069 } while (read_seqcount_retry(&fs
->seq
, seq
));
2071 get_fs_pwd(current
->fs
, &nd
->path
);
2074 /* Caller must check execute permissions on the starting path component */
2075 struct fd f
= fdget_raw(nd
->dfd
);
2076 struct dentry
*dentry
;
2079 return ERR_PTR(-EBADF
);
2081 dentry
= f
.file
->f_path
.dentry
;
2084 if (!d_can_lookup(dentry
)) {
2086 return ERR_PTR(-ENOTDIR
);
2090 nd
->path
= f
.file
->f_path
;
2091 if (flags
& LOOKUP_RCU
) {
2093 nd
->inode
= nd
->path
.dentry
->d_inode
;
2094 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2096 path_get(&nd
->path
);
2097 nd
->inode
= nd
->path
.dentry
->d_inode
;
2103 nd
->inode
= nd
->path
.dentry
->d_inode
;
2104 if (!(flags
& LOOKUP_RCU
))
2106 if (likely(!read_seqcount_retry(&nd
->path
.dentry
->d_seq
, nd
->seq
)))
2108 if (!(nd
->flags
& LOOKUP_ROOT
))
2109 nd
->root
.mnt
= NULL
;
2111 return ERR_PTR(-ECHILD
);
2114 static const char *trailing_symlink(struct nameidata
*nd
)
2117 int error
= may_follow_link(nd
);
2118 if (unlikely(error
))
2119 return ERR_PTR(error
);
2120 nd
->flags
|= LOOKUP_PARENT
;
2121 nd
->stack
[0].name
= NULL
;
2126 static inline int lookup_last(struct nameidata
*nd
)
2128 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
2129 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2131 nd
->flags
&= ~LOOKUP_PARENT
;
2132 return walk_component(nd
,
2133 nd
->flags
& LOOKUP_FOLLOW
2135 ? WALK_PUT
| WALK_GET
2140 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2141 static int path_lookupat(struct nameidata
*nd
, unsigned flags
, struct path
*path
)
2143 const char *s
= path_init(nd
, flags
);
2148 while (!(err
= link_path_walk(s
, nd
))
2149 && ((err
= lookup_last(nd
)) > 0)) {
2150 s
= trailing_symlink(nd
);
2157 err
= complete_walk(nd
);
2159 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
)
2160 if (!d_can_lookup(nd
->path
.dentry
))
2164 nd
->path
.mnt
= NULL
;
2165 nd
->path
.dentry
= NULL
;
2171 static int filename_lookup(int dfd
, struct filename
*name
, unsigned flags
,
2172 struct path
*path
, struct path
*root
)
2175 struct nameidata nd
;
2177 return PTR_ERR(name
);
2178 if (unlikely(root
)) {
2180 flags
|= LOOKUP_ROOT
;
2182 set_nameidata(&nd
, dfd
, name
);
2183 retval
= path_lookupat(&nd
, flags
| LOOKUP_RCU
, path
);
2184 if (unlikely(retval
== -ECHILD
))
2185 retval
= path_lookupat(&nd
, flags
, path
);
2186 if (unlikely(retval
== -ESTALE
))
2187 retval
= path_lookupat(&nd
, flags
| LOOKUP_REVAL
, path
);
2189 if (likely(!retval
))
2190 audit_inode(name
, path
->dentry
, flags
& LOOKUP_PARENT
);
2191 restore_nameidata();
2196 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2197 static int path_parentat(struct nameidata
*nd
, unsigned flags
,
2198 struct path
*parent
)
2200 const char *s
= path_init(nd
, flags
);
2204 err
= link_path_walk(s
, nd
);
2206 err
= complete_walk(nd
);
2209 nd
->path
.mnt
= NULL
;
2210 nd
->path
.dentry
= NULL
;
2216 static struct filename
*filename_parentat(int dfd
, struct filename
*name
,
2217 unsigned int flags
, struct path
*parent
,
2218 struct qstr
*last
, int *type
)
2221 struct nameidata nd
;
2225 set_nameidata(&nd
, dfd
, name
);
2226 retval
= path_parentat(&nd
, flags
| LOOKUP_RCU
, parent
);
2227 if (unlikely(retval
== -ECHILD
))
2228 retval
= path_parentat(&nd
, flags
, parent
);
2229 if (unlikely(retval
== -ESTALE
))
2230 retval
= path_parentat(&nd
, flags
| LOOKUP_REVAL
, parent
);
2231 if (likely(!retval
)) {
2233 *type
= nd
.last_type
;
2234 audit_inode(name
, parent
->dentry
, LOOKUP_PARENT
);
2237 name
= ERR_PTR(retval
);
2239 restore_nameidata();
2243 /* does lookup, returns the object with parent locked */
2244 struct dentry
*kern_path_locked(const char *name
, struct path
*path
)
2246 struct filename
*filename
;
2251 filename
= filename_parentat(AT_FDCWD
, getname_kernel(name
), 0, path
,
2253 if (IS_ERR(filename
))
2254 return ERR_CAST(filename
);
2255 if (unlikely(type
!= LAST_NORM
)) {
2258 return ERR_PTR(-EINVAL
);
2260 mutex_lock_nested(&path
->dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2261 d
= __lookup_hash(&last
, path
->dentry
, 0);
2263 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
2270 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
2272 return filename_lookup(AT_FDCWD
, getname_kernel(name
),
2275 EXPORT_SYMBOL(kern_path
);
2278 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2279 * @dentry: pointer to dentry of the base directory
2280 * @mnt: pointer to vfs mount of the base directory
2281 * @name: pointer to file name
2282 * @flags: lookup flags
2283 * @path: pointer to struct path to fill
2285 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
2286 const char *name
, unsigned int flags
,
2289 struct path root
= {.mnt
= mnt
, .dentry
= dentry
};
2290 /* the first argument of filename_lookup() is ignored with root */
2291 return filename_lookup(AT_FDCWD
, getname_kernel(name
),
2292 flags
, path
, &root
);
2294 EXPORT_SYMBOL(vfs_path_lookup
);
2297 * lookup_one_len - filesystem helper to lookup single pathname component
2298 * @name: pathname component to lookup
2299 * @mnt: mount we are looking up on
2300 * @base: base directory to lookup from
2301 * @len: maximum length @len should be interpreted to
2303 * Note that this routine is purely a helper for filesystem usage and should
2304 * not be called by generic code.
2306 struct dentry
*lookup_one_len2(const char *name
, struct vfsmount
*mnt
, struct dentry
*base
, int len
)
2312 WARN_ON_ONCE(!mutex_is_locked(&base
->d_inode
->i_mutex
));
2316 this.hash
= full_name_hash(name
, len
);
2318 return ERR_PTR(-EACCES
);
2320 if (unlikely(name
[0] == '.')) {
2321 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2322 return ERR_PTR(-EACCES
);
2326 c
= *(const unsigned char *)name
++;
2327 if (c
== '/' || c
== '\0')
2328 return ERR_PTR(-EACCES
);
2331 * See if the low-level filesystem might want
2332 * to use its own hash..
2334 if (base
->d_flags
& DCACHE_OP_HASH
) {
2335 int err
= base
->d_op
->d_hash(base
, &this);
2337 return ERR_PTR(err
);
2340 err
= inode_permission2(mnt
, base
->d_inode
, MAY_EXEC
);
2342 return ERR_PTR(err
);
2344 return __lookup_hash(&this, base
, 0);
2346 EXPORT_SYMBOL(lookup_one_len2
);
2348 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2350 return lookup_one_len2(name
, NULL
, base
, len
);
2352 EXPORT_SYMBOL(lookup_one_len
);
2354 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
2355 struct path
*path
, int *empty
)
2357 return filename_lookup(dfd
, getname_flags(name
, flags
, empty
),
2360 EXPORT_SYMBOL(user_path_at_empty
);
2363 * NB: most callers don't do anything directly with the reference to the
2364 * to struct filename, but the nd->last pointer points into the name string
2365 * allocated by getname. So we must hold the reference to it until all
2366 * path-walking is complete.
2368 static inline struct filename
*
2369 user_path_parent(int dfd
, const char __user
*path
,
2370 struct path
*parent
,
2375 /* only LOOKUP_REVAL is allowed in extra flags */
2376 return filename_parentat(dfd
, getname(path
), flags
& LOOKUP_REVAL
,
2377 parent
, last
, type
);
2381 * mountpoint_last - look up last component for umount
2382 * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
2383 * @path: pointer to container for result
2385 * This is a special lookup_last function just for umount. In this case, we
2386 * need to resolve the path without doing any revalidation.
2388 * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
2389 * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
2390 * in almost all cases, this lookup will be served out of the dcache. The only
2391 * cases where it won't are if nd->last refers to a symlink or the path is
2392 * bogus and it doesn't exist.
2395 * -error: if there was an error during lookup. This includes -ENOENT if the
2396 * lookup found a negative dentry. The nd->path reference will also be
2399 * 0: if we successfully resolved nd->path and found it to not to be a
2400 * symlink that needs to be followed. "path" will also be populated.
2401 * The nd->path reference will also be put.
2403 * 1: if we successfully resolved nd->last and found it to be a symlink
2404 * that needs to be followed. "path" will be populated with the path
2405 * to the link, and nd->path will *not* be put.
2408 mountpoint_last(struct nameidata
*nd
, struct path
*path
)
2411 struct dentry
*dentry
;
2412 struct dentry
*dir
= nd
->path
.dentry
;
2414 /* If we're in rcuwalk, drop out of it to handle last component */
2415 if (nd
->flags
& LOOKUP_RCU
) {
2416 if (unlazy_walk(nd
, NULL
, 0))
2420 nd
->flags
&= ~LOOKUP_PARENT
;
2422 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
2423 error
= handle_dots(nd
, nd
->last_type
);
2426 dentry
= dget(nd
->path
.dentry
);
2430 mutex_lock(&dir
->d_inode
->i_mutex
);
2431 dentry
= d_lookup(dir
, &nd
->last
);
2434 * No cached dentry. Mounted dentries are pinned in the cache,
2435 * so that means that this dentry is probably a symlink or the
2436 * path doesn't actually point to a mounted dentry.
2438 dentry
= d_alloc(dir
, &nd
->last
);
2440 mutex_unlock(&dir
->d_inode
->i_mutex
);
2443 dentry
= lookup_real(dir
->d_inode
, dentry
, nd
->flags
);
2444 if (IS_ERR(dentry
)) {
2445 mutex_unlock(&dir
->d_inode
->i_mutex
);
2446 return PTR_ERR(dentry
);
2449 mutex_unlock(&dir
->d_inode
->i_mutex
);
2452 if (d_is_negative(dentry
)) {
2458 path
->dentry
= dentry
;
2459 path
->mnt
= nd
->path
.mnt
;
2460 error
= should_follow_link(nd
, path
, nd
->flags
& LOOKUP_FOLLOW
,
2461 d_backing_inode(dentry
), 0);
2462 if (unlikely(error
))
2470 * path_mountpoint - look up a path to be umounted
2471 * @nd: lookup context
2472 * @flags: lookup flags
2473 * @path: pointer to container for result
2475 * Look up the given name, but don't attempt to revalidate the last component.
2476 * Returns 0 and "path" will be valid on success; Returns error otherwise.
2479 path_mountpoint(struct nameidata
*nd
, unsigned flags
, struct path
*path
)
2481 const char *s
= path_init(nd
, flags
);
2485 while (!(err
= link_path_walk(s
, nd
)) &&
2486 (err
= mountpoint_last(nd
, path
)) > 0) {
2487 s
= trailing_symlink(nd
);
2498 filename_mountpoint(int dfd
, struct filename
*name
, struct path
*path
,
2501 struct nameidata nd
;
2504 return PTR_ERR(name
);
2505 set_nameidata(&nd
, dfd
, name
);
2506 error
= path_mountpoint(&nd
, flags
| LOOKUP_RCU
, path
);
2507 if (unlikely(error
== -ECHILD
))
2508 error
= path_mountpoint(&nd
, flags
, path
);
2509 if (unlikely(error
== -ESTALE
))
2510 error
= path_mountpoint(&nd
, flags
| LOOKUP_REVAL
, path
);
2512 audit_inode(name
, path
->dentry
, 0);
2513 restore_nameidata();
2519 * user_path_mountpoint_at - lookup a path from userland in order to umount it
2520 * @dfd: directory file descriptor
2521 * @name: pathname from userland
2522 * @flags: lookup flags
2523 * @path: pointer to container to hold result
2525 * A umount is a special case for path walking. We're not actually interested
2526 * in the inode in this situation, and ESTALE errors can be a problem. We
2527 * simply want track down the dentry and vfsmount attached at the mountpoint
2528 * and avoid revalidating the last component.
2530 * Returns 0 and populates "path" on success.
2533 user_path_mountpoint_at(int dfd
, const char __user
*name
, unsigned int flags
,
2536 return filename_mountpoint(dfd
, getname(name
), path
, flags
);
2540 kern_path_mountpoint(int dfd
, const char *name
, struct path
*path
,
2543 return filename_mountpoint(dfd
, getname_kernel(name
), path
, flags
);
2545 EXPORT_SYMBOL(kern_path_mountpoint
);
2547 int __check_sticky(struct inode
*dir
, struct inode
*inode
)
2549 kuid_t fsuid
= current_fsuid();
2551 if (uid_eq(inode
->i_uid
, fsuid
))
2553 if (uid_eq(dir
->i_uid
, fsuid
))
2555 return !capable_wrt_inode_uidgid(inode
, CAP_FOWNER
);
2557 EXPORT_SYMBOL(__check_sticky
);
2560 * Check whether we can remove a link victim from directory dir, check
2561 * whether the type of victim is right.
2562 * 1. We can't do it if dir is read-only (done in permission())
2563 * 2. We should have write and exec permissions on dir
2564 * 3. We can't remove anything from append-only dir
2565 * 4. We can't do anything with immutable dir (done in permission())
2566 * 5. If the sticky bit on dir is set we should either
2567 * a. be owner of dir, or
2568 * b. be owner of victim, or
2569 * c. have CAP_FOWNER capability
2570 * 6. If the victim is append-only or immutable we can't do antyhing with
2571 * links pointing to it.
2572 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2573 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2574 * 9. We can't remove a root or mountpoint.
2575 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
2576 * nfs_async_unlink().
2578 static int may_delete(struct vfsmount
*mnt
, struct inode
*dir
, struct dentry
*victim
, bool isdir
)
2580 struct inode
*inode
= d_backing_inode(victim
);
2583 if (d_is_negative(victim
))
2587 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
2588 audit_inode_child(dir
, victim
, AUDIT_TYPE_CHILD_DELETE
);
2590 error
= inode_permission2(mnt
, dir
, MAY_WRITE
| MAY_EXEC
);
2596 if (check_sticky(dir
, inode
) || IS_APPEND(inode
) ||
2597 IS_IMMUTABLE(inode
) || IS_SWAPFILE(inode
))
2600 if (!d_is_dir(victim
))
2602 if (IS_ROOT(victim
))
2604 } else if (d_is_dir(victim
))
2606 if (IS_DEADDIR(dir
))
2608 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2613 /* Check whether we can create an object with dentry child in directory
2615 * 1. We can't do it if child already exists (open has special treatment for
2616 * this case, but since we are inlined it's OK)
2617 * 2. We can't do it if dir is read-only (done in permission())
2618 * 3. We should have write and exec permissions on dir
2619 * 4. We can't do it if dir is immutable (done in permission())
2621 static inline int may_create(struct vfsmount
*mnt
, struct inode
*dir
, struct dentry
*child
)
2623 audit_inode_child(dir
, child
, AUDIT_TYPE_CHILD_CREATE
);
2626 if (IS_DEADDIR(dir
))
2628 return inode_permission2(mnt
, dir
, MAY_WRITE
| MAY_EXEC
);
2632 * p1 and p2 should be directories on the same fs.
2634 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2639 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2643 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2645 p
= d_ancestor(p2
, p1
);
2647 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2648 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2652 p
= d_ancestor(p1
, p2
);
2654 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2655 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2659 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2660 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT2
);
2663 EXPORT_SYMBOL(lock_rename
);
2665 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
2667 mutex_unlock(&p1
->d_inode
->i_mutex
);
2669 mutex_unlock(&p2
->d_inode
->i_mutex
);
2670 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2673 EXPORT_SYMBOL(unlock_rename
);
2675 int vfs_create2(struct vfsmount
*mnt
, struct inode
*dir
, struct dentry
*dentry
,
2676 umode_t mode
, bool want_excl
)
2678 int error
= may_create(mnt
, dir
, dentry
);
2682 if (!dir
->i_op
->create
)
2683 return -EACCES
; /* shouldn't it be ENOSYS? */
2686 error
= security_inode_create(dir
, dentry
, mode
);
2689 error
= dir
->i_op
->create(dir
, dentry
, mode
, want_excl
);
2691 fsnotify_create(dir
, dentry
);
2694 EXPORT_SYMBOL(vfs_create2
);
2696 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
2699 return vfs_create2(NULL
, dir
, dentry
, mode
, want_excl
);
2701 EXPORT_SYMBOL(vfs_create
);
2703 static int may_open(struct path
*path
, int acc_mode
, int flag
)
2705 struct dentry
*dentry
= path
->dentry
;
2706 struct vfsmount
*mnt
= path
->mnt
;
2707 struct inode
*inode
= dentry
->d_inode
;
2717 switch (inode
->i_mode
& S_IFMT
) {
2721 if (acc_mode
& MAY_WRITE
)
2726 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
2735 error
= inode_permission2(mnt
, inode
, acc_mode
);
2740 * An append-only file must be opened in append mode for writing.
2742 if (IS_APPEND(inode
)) {
2743 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
2749 /* O_NOATIME can only be set by the owner or superuser */
2750 if (flag
& O_NOATIME
&& !inode_owner_or_capable(inode
))
2756 static int handle_truncate(struct file
*filp
)
2758 struct path
*path
= &filp
->f_path
;
2759 struct inode
*inode
= path
->dentry
->d_inode
;
2760 int error
= get_write_access(inode
);
2764 * Refuse to truncate files with mandatory locks held on them.
2766 error
= locks_verify_locked(filp
);
2768 error
= security_path_truncate(path
);
2770 error
= do_truncate2(path
->mnt
, path
->dentry
, 0,
2771 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
2774 put_write_access(inode
);
2778 static inline int open_to_namei_flags(int flag
)
2780 if ((flag
& O_ACCMODE
) == 3)
2785 static int may_o_create(struct path
*dir
, struct dentry
*dentry
, umode_t mode
)
2787 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
2791 error
= inode_permission2(dir
->mnt
, dir
->dentry
->d_inode
, MAY_WRITE
| MAY_EXEC
);
2795 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
2799 * Attempt to atomically look up, create and open a file from a negative
2802 * Returns 0 if successful. The file will have been created and attached to
2803 * @file by the filesystem calling finish_open().
2805 * Returns 1 if the file was looked up only or didn't need creating. The
2806 * caller will need to perform the open themselves. @path will have been
2807 * updated to point to the new dentry. This may be negative.
2809 * Returns an error code otherwise.
2811 static int atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
2812 struct path
*path
, struct file
*file
,
2813 const struct open_flags
*op
,
2814 bool got_write
, bool need_lookup
,
2817 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
2818 unsigned open_flag
= open_to_namei_flags(op
->open_flag
);
2822 int create_error
= 0;
2823 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
2826 BUG_ON(dentry
->d_inode
);
2828 /* Don't create child dentry for a dead directory. */
2829 if (unlikely(IS_DEADDIR(dir
))) {
2835 if ((open_flag
& O_CREAT
) && !IS_POSIXACL(dir
))
2836 mode
&= ~current_umask();
2838 excl
= (open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
);
2840 open_flag
&= ~O_TRUNC
;
2843 * Checking write permission is tricky, bacuse we don't know if we are
2844 * going to actually need it: O_CREAT opens should work as long as the
2845 * file exists. But checking existence breaks atomicity. The trick is
2846 * to check access and if not granted clear O_CREAT from the flags.
2848 * Another problem is returing the "right" error value (e.g. for an
2849 * O_EXCL open we want to return EEXIST not EROFS).
2851 if (((open_flag
& (O_CREAT
| O_TRUNC
)) ||
2852 (open_flag
& O_ACCMODE
) != O_RDONLY
) && unlikely(!got_write
)) {
2853 if (!(open_flag
& O_CREAT
)) {
2855 * No O_CREATE -> atomicity not a requirement -> fall
2856 * back to lookup + open
2859 } else if (open_flag
& (O_EXCL
| O_TRUNC
)) {
2860 /* Fall back and fail with the right error */
2861 create_error
= -EROFS
;
2864 /* No side effects, safe to clear O_CREAT */
2865 create_error
= -EROFS
;
2866 open_flag
&= ~O_CREAT
;
2870 if (open_flag
& O_CREAT
) {
2871 error
= may_o_create(&nd
->path
, dentry
, mode
);
2873 create_error
= error
;
2874 if (open_flag
& O_EXCL
)
2876 open_flag
&= ~O_CREAT
;
2880 if (nd
->flags
& LOOKUP_DIRECTORY
)
2881 open_flag
|= O_DIRECTORY
;
2883 file
->f_path
.dentry
= DENTRY_NOT_SET
;
2884 file
->f_path
.mnt
= nd
->path
.mnt
;
2885 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
, open_flag
, mode
,
2888 if (create_error
&& error
== -ENOENT
)
2889 error
= create_error
;
2893 if (error
) { /* returned 1, that is */
2894 if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
2898 if (file
->f_path
.dentry
) {
2900 dentry
= file
->f_path
.dentry
;
2902 if (*opened
& FILE_CREATED
)
2903 fsnotify_create(dir
, dentry
);
2904 if (!dentry
->d_inode
) {
2905 WARN_ON(*opened
& FILE_CREATED
);
2907 error
= create_error
;
2911 if (excl
&& !(*opened
& FILE_CREATED
)) {
2920 * We didn't have the inode before the open, so check open permission
2923 acc_mode
= op
->acc_mode
;
2924 if (*opened
& FILE_CREATED
) {
2925 WARN_ON(!(open_flag
& O_CREAT
));
2926 fsnotify_create(dir
, dentry
);
2927 acc_mode
= MAY_OPEN
;
2929 error
= may_open(&file
->f_path
, acc_mode
, open_flag
);
2939 dentry
= lookup_real(dir
, dentry
, nd
->flags
);
2941 return PTR_ERR(dentry
);
2943 if (create_error
&& !dentry
->d_inode
) {
2944 error
= create_error
;
2948 path
->dentry
= dentry
;
2949 path
->mnt
= nd
->path
.mnt
;
2954 * Look up and maybe create and open the last component.
2956 * Must be called with i_mutex held on parent.
2958 * Returns 0 if the file was successfully atomically created (if necessary) and
2959 * opened. In this case the file will be returned attached to @file.
2961 * Returns 1 if the file was not completely opened at this time, though lookups
2962 * and creations will have been performed and the dentry returned in @path will
2963 * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
2964 * specified then a negative dentry may be returned.
2966 * An error code is returned otherwise.
2968 * FILE_CREATE will be set in @*opened if the dentry was created and will be
2969 * cleared otherwise prior to returning.
2971 static int lookup_open(struct nameidata
*nd
, struct path
*path
,
2973 const struct open_flags
*op
,
2974 bool got_write
, int *opened
)
2976 struct dentry
*dir
= nd
->path
.dentry
;
2977 struct vfsmount
*mnt
= nd
->path
.mnt
;
2978 struct inode
*dir_inode
= dir
->d_inode
;
2979 struct dentry
*dentry
;
2983 *opened
&= ~FILE_CREATED
;
2984 dentry
= lookup_dcache(&nd
->last
, dir
, nd
->flags
, &need_lookup
);
2986 return PTR_ERR(dentry
);
2988 /* Cached positive dentry: will open in f_op->open */
2989 if (!need_lookup
&& dentry
->d_inode
)
2992 if ((nd
->flags
& LOOKUP_OPEN
) && dir_inode
->i_op
->atomic_open
) {
2993 return atomic_open(nd
, dentry
, path
, file
, op
, got_write
,
2994 need_lookup
, opened
);
2998 BUG_ON(dentry
->d_inode
);
3000 dentry
= lookup_real(dir_inode
, dentry
, nd
->flags
);
3002 return PTR_ERR(dentry
);
3005 /* Negative dentry, just create the file */
3006 if (!dentry
->d_inode
&& (op
->open_flag
& O_CREAT
)) {
3007 umode_t mode
= op
->mode
;
3008 if (!IS_POSIXACL(dir
->d_inode
))
3009 mode
&= ~current_umask();
3011 * This write is needed to ensure that a
3012 * rw->ro transition does not occur between
3013 * the time when the file is created and when
3014 * a permanent write count is taken through
3015 * the 'struct file' in finish_open().
3021 *opened
|= FILE_CREATED
;
3022 error
= security_path_mknod(&nd
->path
, dentry
, mode
, 0);
3025 error
= vfs_create2(mnt
, dir
->d_inode
, dentry
, mode
,
3026 nd
->flags
& LOOKUP_EXCL
);
3031 path
->dentry
= dentry
;
3032 path
->mnt
= nd
->path
.mnt
;
3041 * Handle the last step of open()
3043 static int do_last(struct nameidata
*nd
,
3044 struct file
*file
, const struct open_flags
*op
,
3047 struct dentry
*dir
= nd
->path
.dentry
;
3048 int open_flag
= op
->open_flag
;
3049 bool will_truncate
= (open_flag
& O_TRUNC
) != 0;
3050 bool got_write
= false;
3051 int acc_mode
= op
->acc_mode
;
3053 struct inode
*inode
;
3054 struct path save_parent
= { .dentry
= NULL
, .mnt
= NULL
};
3056 bool retried
= false;
3059 nd
->flags
&= ~LOOKUP_PARENT
;
3060 nd
->flags
|= op
->intent
;
3062 if (nd
->last_type
!= LAST_NORM
) {
3063 error
= handle_dots(nd
, nd
->last_type
);
3064 if (unlikely(error
))
3069 if (!(open_flag
& O_CREAT
)) {
3070 if (nd
->last
.name
[nd
->last
.len
])
3071 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
3072 /* we _can_ be in RCU mode here */
3073 error
= lookup_fast(nd
, &path
, &inode
, &seq
);
3080 BUG_ON(nd
->inode
!= dir
->d_inode
);
3082 /* create side of things */
3084 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
3085 * has been cleared when we got to the last component we are
3088 error
= complete_walk(nd
);
3092 audit_inode(nd
->name
, dir
, LOOKUP_PARENT
);
3093 /* trailing slashes? */
3094 if (unlikely(nd
->last
.name
[nd
->last
.len
]))
3099 if (op
->open_flag
& (O_CREAT
| O_TRUNC
| O_WRONLY
| O_RDWR
)) {
3100 error
= mnt_want_write(nd
->path
.mnt
);
3104 * do _not_ fail yet - we might not need that or fail with
3105 * a different error; let lookup_open() decide; we'll be
3106 * dropping this one anyway.
3109 mutex_lock(&dir
->d_inode
->i_mutex
);
3110 error
= lookup_open(nd
, &path
, file
, op
, got_write
, opened
);
3111 mutex_unlock(&dir
->d_inode
->i_mutex
);
3117 if ((*opened
& FILE_CREATED
) ||
3118 !S_ISREG(file_inode(file
)->i_mode
))
3119 will_truncate
= false;
3121 audit_inode(nd
->name
, file
->f_path
.dentry
, 0);
3125 if (*opened
& FILE_CREATED
) {
3126 /* Don't check for write permission, don't truncate */
3127 open_flag
&= ~O_TRUNC
;
3128 will_truncate
= false;
3129 acc_mode
= MAY_OPEN
;
3130 path_to_nameidata(&path
, nd
);
3131 goto finish_open_created
;
3135 * create/update audit record if it already exists.
3137 if (d_is_positive(path
.dentry
))
3138 audit_inode(nd
->name
, path
.dentry
, 0);
3141 * If atomic_open() acquired write access it is dropped now due to
3142 * possible mount and symlink following (this might be optimized away if
3146 mnt_drop_write(nd
->path
.mnt
);
3150 if (unlikely((open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
))) {
3151 path_to_nameidata(&path
, nd
);
3155 error
= follow_managed(&path
, nd
);
3156 if (unlikely(error
< 0))
3159 BUG_ON(nd
->flags
& LOOKUP_RCU
);
3160 seq
= 0; /* out of RCU mode, so the value doesn't matter */
3161 if (unlikely(d_is_negative(path
.dentry
))) {
3162 path_to_nameidata(&path
, nd
);
3165 inode
= d_backing_inode(path
.dentry
);
3169 error
= should_follow_link(nd
, &path
, nd
->flags
& LOOKUP_FOLLOW
,
3171 if (unlikely(error
))
3174 if ((nd
->flags
& LOOKUP_RCU
) || nd
->path
.mnt
!= path
.mnt
) {
3175 path_to_nameidata(&path
, nd
);
3177 save_parent
.dentry
= nd
->path
.dentry
;
3178 save_parent
.mnt
= mntget(path
.mnt
);
3179 nd
->path
.dentry
= path
.dentry
;
3184 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
3186 error
= complete_walk(nd
);
3188 path_put(&save_parent
);
3191 audit_inode(nd
->name
, nd
->path
.dentry
, 0);
3192 if (unlikely(d_is_symlink(nd
->path
.dentry
)) && !(open_flag
& O_PATH
)) {
3197 if ((open_flag
& O_CREAT
) && d_is_dir(nd
->path
.dentry
))
3200 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !d_can_lookup(nd
->path
.dentry
))
3202 if (!d_is_reg(nd
->path
.dentry
))
3203 will_truncate
= false;
3205 if (will_truncate
) {
3206 error
= mnt_want_write(nd
->path
.mnt
);
3211 finish_open_created
:
3212 error
= may_open(&nd
->path
, acc_mode
, open_flag
);
3216 BUG_ON(*opened
& FILE_OPENED
); /* once it's opened, it's opened */
3217 error
= vfs_open(&nd
->path
, file
, current_cred());
3219 *opened
|= FILE_OPENED
;
3221 if (error
== -EOPENSTALE
)
3226 error
= open_check_o_direct(file
);
3229 error
= ima_file_check(file
, op
->acc_mode
, *opened
);
3233 if (will_truncate
) {
3234 error
= handle_truncate(file
);
3239 if (unlikely(error
> 0)) {
3244 mnt_drop_write(nd
->path
.mnt
);
3245 path_put(&save_parent
);
3253 /* If no saved parent or already retried then can't retry */
3254 if (!save_parent
.dentry
|| retried
)
3257 BUG_ON(save_parent
.dentry
!= dir
);
3258 path_put(&nd
->path
);
3259 nd
->path
= save_parent
;
3260 nd
->inode
= dir
->d_inode
;
3261 save_parent
.mnt
= NULL
;
3262 save_parent
.dentry
= NULL
;
3264 mnt_drop_write(nd
->path
.mnt
);
3271 static int do_tmpfile(struct nameidata
*nd
, unsigned flags
,
3272 const struct open_flags
*op
,
3273 struct file
*file
, int *opened
)
3275 static const struct qstr name
= QSTR_INIT("/", 1);
3276 struct dentry
*child
;
3279 int error
= path_lookupat(nd
, flags
| LOOKUP_DIRECTORY
, &path
);
3280 if (unlikely(error
))
3282 error
= mnt_want_write(path
.mnt
);
3283 if (unlikely(error
))
3285 dir
= path
.dentry
->d_inode
;
3286 /* we want directory to be writable */
3287 error
= inode_permission2(path
.mnt
, dir
, MAY_WRITE
| MAY_EXEC
);
3290 if (!dir
->i_op
->tmpfile
) {
3291 error
= -EOPNOTSUPP
;
3294 child
= d_alloc(path
.dentry
, &name
);
3295 if (unlikely(!child
)) {
3300 path
.dentry
= child
;
3301 error
= dir
->i_op
->tmpfile(dir
, child
, op
->mode
);
3304 audit_inode(nd
->name
, child
, 0);
3305 /* Don't check for other permissions, the inode was just created */
3306 error
= may_open(&path
, MAY_OPEN
, op
->open_flag
);
3309 file
->f_path
.mnt
= path
.mnt
;
3310 error
= finish_open(file
, child
, NULL
, opened
);
3313 error
= open_check_o_direct(file
);
3316 } else if (!(op
->open_flag
& O_EXCL
)) {
3317 struct inode
*inode
= file_inode(file
);
3318 spin_lock(&inode
->i_lock
);
3319 inode
->i_state
|= I_LINKABLE
;
3320 spin_unlock(&inode
->i_lock
);
3323 mnt_drop_write(path
.mnt
);
3329 static struct file
*path_openat(struct nameidata
*nd
,
3330 const struct open_flags
*op
, unsigned flags
)
3337 file
= get_empty_filp();
3341 file
->f_flags
= op
->open_flag
;
3343 if (unlikely(file
->f_flags
& __O_TMPFILE
)) {
3344 error
= do_tmpfile(nd
, flags
, op
, file
, &opened
);
3348 s
= path_init(nd
, flags
);
3353 while (!(error
= link_path_walk(s
, nd
)) &&
3354 (error
= do_last(nd
, file
, op
, &opened
)) > 0) {
3355 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
3356 s
= trailing_symlink(nd
);
3364 if (!(opened
& FILE_OPENED
)) {
3368 if (unlikely(error
)) {
3369 if (error
== -EOPENSTALE
) {
3370 if (flags
& LOOKUP_RCU
)
3375 file
= ERR_PTR(error
);
3380 struct file
*do_filp_open(int dfd
, struct filename
*pathname
,
3381 const struct open_flags
*op
)
3383 struct nameidata nd
;
3384 int flags
= op
->lookup_flags
;
3387 set_nameidata(&nd
, dfd
, pathname
);
3388 filp
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3389 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
3390 filp
= path_openat(&nd
, op
, flags
);
3391 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
3392 filp
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3393 restore_nameidata();
3397 struct file
*do_file_open_root(struct dentry
*dentry
, struct vfsmount
*mnt
,
3398 const char *name
, const struct open_flags
*op
)
3400 struct nameidata nd
;
3402 struct filename
*filename
;
3403 int flags
= op
->lookup_flags
| LOOKUP_ROOT
;
3406 nd
.root
.dentry
= dentry
;
3408 if (d_is_symlink(dentry
) && op
->intent
& LOOKUP_OPEN
)
3409 return ERR_PTR(-ELOOP
);
3411 filename
= getname_kernel(name
);
3412 if (IS_ERR(filename
))
3413 return ERR_CAST(filename
);
3415 set_nameidata(&nd
, -1, filename
);
3416 file
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3417 if (unlikely(file
== ERR_PTR(-ECHILD
)))
3418 file
= path_openat(&nd
, op
, flags
);
3419 if (unlikely(file
== ERR_PTR(-ESTALE
)))
3420 file
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3421 restore_nameidata();
3426 static struct dentry
*filename_create(int dfd
, struct filename
*name
,
3427 struct path
*path
, unsigned int lookup_flags
)
3429 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
3434 bool is_dir
= (lookup_flags
& LOOKUP_DIRECTORY
);
3437 * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
3438 * other flags passed in are ignored!
3440 lookup_flags
&= LOOKUP_REVAL
;
3442 name
= filename_parentat(dfd
, name
, lookup_flags
, path
, &last
, &type
);
3444 return ERR_CAST(name
);
3447 * Yucky last component or no last component at all?
3448 * (foo/., foo/.., /////)
3450 if (unlikely(type
!= LAST_NORM
))
3453 /* don't fail immediately if it's r/o, at least try to report other errors */
3454 err2
= mnt_want_write(path
->mnt
);
3456 * Do the final lookup.
3458 lookup_flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
3459 mutex_lock_nested(&path
->dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3460 dentry
= __lookup_hash(&last
, path
->dentry
, lookup_flags
);
3465 if (d_is_positive(dentry
))
3469 * Special case - lookup gave negative, but... we had foo/bar/
3470 * From the vfs_mknod() POV we just have a negative dentry -
3471 * all is fine. Let's be bastards - you had / on the end, you've
3472 * been asking for (non-existent) directory. -ENOENT for you.
3474 if (unlikely(!is_dir
&& last
.name
[last
.len
])) {
3478 if (unlikely(err2
)) {
3486 dentry
= ERR_PTR(error
);
3488 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
3490 mnt_drop_write(path
->mnt
);
3497 struct dentry
*kern_path_create(int dfd
, const char *pathname
,
3498 struct path
*path
, unsigned int lookup_flags
)
3500 return filename_create(dfd
, getname_kernel(pathname
),
3501 path
, lookup_flags
);
3503 EXPORT_SYMBOL(kern_path_create
);
3505 void done_path_create(struct path
*path
, struct dentry
*dentry
)
3508 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
3509 mnt_drop_write(path
->mnt
);
3512 EXPORT_SYMBOL(done_path_create
);
3514 inline struct dentry
*user_path_create(int dfd
, const char __user
*pathname
,
3515 struct path
*path
, unsigned int lookup_flags
)
3517 return filename_create(dfd
, getname(pathname
), path
, lookup_flags
);
3519 EXPORT_SYMBOL(user_path_create
);
3521 int vfs_mknod2(struct vfsmount
*mnt
, struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3523 int error
= may_create(mnt
, dir
, dentry
);
3528 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
3531 if (!dir
->i_op
->mknod
)
3534 error
= devcgroup_inode_mknod(mode
, dev
);
3538 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
3542 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
3544 fsnotify_create(dir
, dentry
);
3547 EXPORT_SYMBOL(vfs_mknod2
);
3549 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3551 return vfs_mknod2(NULL
, dir
, dentry
, mode
, dev
);
3553 EXPORT_SYMBOL(vfs_mknod
);
3555 static int may_mknod(umode_t mode
)
3557 switch (mode
& S_IFMT
) {
3563 case 0: /* zero mode translates to S_IFREG */
3572 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
3575 struct dentry
*dentry
;
3578 unsigned int lookup_flags
= 0;
3580 error
= may_mknod(mode
);
3584 dentry
= user_path_create(dfd
, filename
, &path
, lookup_flags
);
3586 return PTR_ERR(dentry
);
3588 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3589 mode
&= ~current_umask();
3590 error
= security_path_mknod(&path
, dentry
, mode
, dev
);
3593 switch (mode
& S_IFMT
) {
3594 case 0: case S_IFREG
:
3595 error
= vfs_create2(path
.mnt
, path
.dentry
->d_inode
,dentry
,mode
,true);
3597 case S_IFCHR
: case S_IFBLK
:
3598 error
= vfs_mknod2(path
.mnt
, path
.dentry
->d_inode
,dentry
,mode
,
3599 new_decode_dev(dev
));
3601 case S_IFIFO
: case S_IFSOCK
:
3602 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,0);
3606 done_path_create(&path
, dentry
);
3607 if (retry_estale(error
, lookup_flags
)) {
3608 lookup_flags
|= LOOKUP_REVAL
;
3614 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
3616 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
3619 int vfs_mkdir2(struct vfsmount
*mnt
, struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
3621 int error
= may_create(mnt
, dir
, dentry
);
3622 unsigned max_links
= dir
->i_sb
->s_max_links
;
3627 if (!dir
->i_op
->mkdir
)
3630 mode
&= (S_IRWXUGO
|S_ISVTX
);
3631 error
= security_inode_mkdir(dir
, dentry
, mode
);
3635 if (max_links
&& dir
->i_nlink
>= max_links
)
3638 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
3640 fsnotify_mkdir(dir
, dentry
);
3643 EXPORT_SYMBOL(vfs_mkdir2
);
3645 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
3647 return vfs_mkdir2(NULL
, dir
, dentry
, mode
);
3649 EXPORT_SYMBOL(vfs_mkdir
);
3651 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, umode_t
, mode
)
3653 struct dentry
*dentry
;
3656 unsigned int lookup_flags
= LOOKUP_DIRECTORY
;
3659 dentry
= user_path_create(dfd
, pathname
, &path
, lookup_flags
);
3661 return PTR_ERR(dentry
);
3663 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3664 mode
&= ~current_umask();
3665 error
= security_path_mkdir(&path
, dentry
, mode
);
3667 error
= vfs_mkdir2(path
.mnt
, path
.dentry
->d_inode
, dentry
, mode
);
3668 done_path_create(&path
, dentry
);
3669 if (retry_estale(error
, lookup_flags
)) {
3670 lookup_flags
|= LOOKUP_REVAL
;
3676 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, umode_t
, mode
)
3678 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
3682 * The dentry_unhash() helper will try to drop the dentry early: we
3683 * should have a usage count of 1 if we're the only user of this
3684 * dentry, and if that is true (possibly after pruning the dcache),
3685 * then we drop the dentry now.
3687 * A low-level filesystem can, if it choses, legally
3690 * if (!d_unhashed(dentry))
3693 * if it cannot handle the case of removing a directory
3694 * that is still in use by something else..
3696 void dentry_unhash(struct dentry
*dentry
)
3698 shrink_dcache_parent(dentry
);
3699 spin_lock(&dentry
->d_lock
);
3700 if (dentry
->d_lockref
.count
== 1)
3702 spin_unlock(&dentry
->d_lock
);
3704 EXPORT_SYMBOL(dentry_unhash
);
3706 int vfs_rmdir2(struct vfsmount
*mnt
, struct inode
*dir
, struct dentry
*dentry
)
3708 int error
= may_delete(mnt
, dir
, dentry
, 1);
3713 if (!dir
->i_op
->rmdir
)
3717 mutex_lock(&dentry
->d_inode
->i_mutex
);
3720 if (is_local_mountpoint(dentry
))
3723 error
= security_inode_rmdir(dir
, dentry
);
3727 shrink_dcache_parent(dentry
);
3728 error
= dir
->i_op
->rmdir(dir
, dentry
);
3732 dentry
->d_inode
->i_flags
|= S_DEAD
;
3734 detach_mounts(dentry
);
3737 mutex_unlock(&dentry
->d_inode
->i_mutex
);
3743 EXPORT_SYMBOL(vfs_rmdir2
);
3745 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
3747 return vfs_rmdir2(NULL
, dir
, dentry
);
3749 EXPORT_SYMBOL(vfs_rmdir
);
3751 static long do_rmdir(int dfd
, const char __user
*pathname
)
3754 struct filename
*name
;
3755 struct dentry
*dentry
;
3759 unsigned int lookup_flags
= 0;
3761 name
= user_path_parent(dfd
, pathname
,
3762 &path
, &last
, &type
, lookup_flags
);
3764 return PTR_ERR(name
);
3778 error
= mnt_want_write(path
.mnt
);
3782 mutex_lock_nested(&path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3783 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3784 error
= PTR_ERR(dentry
);
3787 if (!dentry
->d_inode
) {
3791 error
= security_path_rmdir(&path
, dentry
);
3794 error
= vfs_rmdir2(path
.mnt
, path
.dentry
->d_inode
, dentry
);
3798 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3799 mnt_drop_write(path
.mnt
);
3803 if (retry_estale(error
, lookup_flags
)) {
3804 lookup_flags
|= LOOKUP_REVAL
;
3810 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
3812 return do_rmdir(AT_FDCWD
, pathname
);
3816 * vfs_unlink - unlink a filesystem object
3817 * @dir: parent directory
3819 * @delegated_inode: returns victim inode, if the inode is delegated.
3821 * The caller must hold dir->i_mutex.
3823 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
3824 * return a reference to the inode in delegated_inode. The caller
3825 * should then break the delegation on that inode and retry. Because
3826 * breaking a delegation may take a long time, the caller should drop
3827 * dir->i_mutex before doing so.
3829 * Alternatively, a caller may pass NULL for delegated_inode. This may
3830 * be appropriate for callers that expect the underlying filesystem not
3831 * to be NFS exported.
3833 int vfs_unlink2(struct vfsmount
*mnt
, struct inode
*dir
, struct dentry
*dentry
, struct inode
**delegated_inode
)
3835 struct inode
*target
= dentry
->d_inode
;
3836 int error
= may_delete(mnt
, dir
, dentry
, 0);
3841 if (!dir
->i_op
->unlink
)
3844 mutex_lock(&target
->i_mutex
);
3845 if (is_local_mountpoint(dentry
))
3848 error
= security_inode_unlink(dir
, dentry
);
3850 error
= try_break_deleg(target
, delegated_inode
);
3853 error
= dir
->i_op
->unlink(dir
, dentry
);
3856 detach_mounts(dentry
);
3861 mutex_unlock(&target
->i_mutex
);
3863 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
3864 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
3865 fsnotify_link_count(target
);
3871 EXPORT_SYMBOL(vfs_unlink2
);
3873 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
, struct inode
**delegated_inode
)
3875 return vfs_unlink2(NULL
, dir
, dentry
, delegated_inode
);
3877 EXPORT_SYMBOL(vfs_unlink
);
3880 * Make sure that the actual truncation of the file will occur outside its
3881 * directory's i_mutex. Truncate can take a long time if there is a lot of
3882 * writeout happening, and we don't want to prevent access to the directory
3883 * while waiting on the I/O.
3885 static long do_unlinkat(int dfd
, const char __user
*pathname
)
3888 struct filename
*name
;
3889 struct dentry
*dentry
;
3893 struct inode
*inode
= NULL
;
3894 struct inode
*delegated_inode
= NULL
;
3895 unsigned int lookup_flags
= 0;
3897 name
= user_path_parent(dfd
, pathname
,
3898 &path
, &last
, &type
, lookup_flags
);
3900 return PTR_ERR(name
);
3903 if (type
!= LAST_NORM
)
3906 error
= mnt_want_write(path
.mnt
);
3910 mutex_lock_nested(&path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3911 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3912 error
= PTR_ERR(dentry
);
3913 if (!IS_ERR(dentry
)) {
3914 /* Why not before? Because we want correct error value */
3915 if (last
.name
[last
.len
])
3917 inode
= dentry
->d_inode
;
3918 if (d_is_negative(dentry
))
3921 error
= security_path_unlink(&path
, dentry
);
3924 error
= vfs_unlink2(path
.mnt
, path
.dentry
->d_inode
, dentry
, &delegated_inode
);
3928 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3930 iput(inode
); /* truncate the inode here */
3932 if (delegated_inode
) {
3933 error
= break_deleg_wait(&delegated_inode
);
3937 mnt_drop_write(path
.mnt
);
3941 if (retry_estale(error
, lookup_flags
)) {
3942 lookup_flags
|= LOOKUP_REVAL
;
3949 if (d_is_negative(dentry
))
3951 else if (d_is_dir(dentry
))
3958 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
3960 if ((flag
& ~AT_REMOVEDIR
) != 0)
3963 if (flag
& AT_REMOVEDIR
)
3964 return do_rmdir(dfd
, pathname
);
3966 return do_unlinkat(dfd
, pathname
);
3969 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
3971 return do_unlinkat(AT_FDCWD
, pathname
);
3974 int vfs_symlink2(struct vfsmount
*mnt
, struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
3976 int error
= may_create(mnt
, dir
, dentry
);
3981 if (!dir
->i_op
->symlink
)
3984 error
= security_inode_symlink(dir
, dentry
, oldname
);
3988 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
3990 fsnotify_create(dir
, dentry
);
3993 EXPORT_SYMBOL(vfs_symlink2
);
3995 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
3997 return vfs_symlink2(NULL
, dir
, dentry
, oldname
);
3999 EXPORT_SYMBOL(vfs_symlink
);
4001 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
4002 int, newdfd
, const char __user
*, newname
)
4005 struct filename
*from
;
4006 struct dentry
*dentry
;
4008 unsigned int lookup_flags
= 0;
4010 from
= getname(oldname
);
4012 return PTR_ERR(from
);
4014 dentry
= user_path_create(newdfd
, newname
, &path
, lookup_flags
);
4015 error
= PTR_ERR(dentry
);
4019 error
= security_path_symlink(&path
, dentry
, from
->name
);
4021 error
= vfs_symlink2(path
.mnt
, path
.dentry
->d_inode
, dentry
, from
->name
);
4022 done_path_create(&path
, dentry
);
4023 if (retry_estale(error
, lookup_flags
)) {
4024 lookup_flags
|= LOOKUP_REVAL
;
4032 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
4034 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
4038 * vfs_link - create a new link
4039 * @old_dentry: object to be linked
4041 * @new_dentry: where to create the new link
4042 * @delegated_inode: returns inode needing a delegation break
4044 * The caller must hold dir->i_mutex
4046 * If vfs_link discovers a delegation on the to-be-linked file in need
4047 * of breaking, it will return -EWOULDBLOCK and return a reference to the
4048 * inode in delegated_inode. The caller should then break the delegation
4049 * and retry. Because breaking a delegation may take a long time, the
4050 * caller should drop the i_mutex before doing so.
4052 * Alternatively, a caller may pass NULL for delegated_inode. This may
4053 * be appropriate for callers that expect the underlying filesystem not
4054 * to be NFS exported.
4056 int vfs_link2(struct vfsmount
*mnt
, struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
, struct inode
**delegated_inode
)
4058 struct inode
*inode
= old_dentry
->d_inode
;
4059 unsigned max_links
= dir
->i_sb
->s_max_links
;
4065 error
= may_create(mnt
, dir
, new_dentry
);
4069 if (dir
->i_sb
!= inode
->i_sb
)
4073 * A link to an append-only or immutable file cannot be created.
4075 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
4077 if (!dir
->i_op
->link
)
4079 if (S_ISDIR(inode
->i_mode
))
4082 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
4086 mutex_lock(&inode
->i_mutex
);
4087 /* Make sure we don't allow creating hardlink to an unlinked file */
4088 if (inode
->i_nlink
== 0 && !(inode
->i_state
& I_LINKABLE
))
4090 else if (max_links
&& inode
->i_nlink
>= max_links
)
4093 error
= try_break_deleg(inode
, delegated_inode
);
4095 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
4098 if (!error
&& (inode
->i_state
& I_LINKABLE
)) {
4099 spin_lock(&inode
->i_lock
);
4100 inode
->i_state
&= ~I_LINKABLE
;
4101 spin_unlock(&inode
->i_lock
);
4103 mutex_unlock(&inode
->i_mutex
);
4105 fsnotify_link(dir
, inode
, new_dentry
);
4108 EXPORT_SYMBOL(vfs_link2
);
4110 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
, struct inode
**delegated_inode
)
4112 return vfs_link2(NULL
, old_dentry
, dir
, new_dentry
, delegated_inode
);
4114 EXPORT_SYMBOL(vfs_link
);
4117 * Hardlinks are often used in delicate situations. We avoid
4118 * security-related surprises by not following symlinks on the
4121 * We don't follow them on the oldname either to be compatible
4122 * with linux 2.0, and to avoid hard-linking to directories
4123 * and other special files. --ADM
4125 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
4126 int, newdfd
, const char __user
*, newname
, int, flags
)
4128 struct dentry
*new_dentry
;
4129 struct path old_path
, new_path
;
4130 struct inode
*delegated_inode
= NULL
;
4134 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0)
4137 * To use null names we require CAP_DAC_READ_SEARCH
4138 * This ensures that not everyone will be able to create
4139 * handlink using the passed filedescriptor.
4141 if (flags
& AT_EMPTY_PATH
) {
4142 if (!capable(CAP_DAC_READ_SEARCH
))
4147 if (flags
& AT_SYMLINK_FOLLOW
)
4148 how
|= LOOKUP_FOLLOW
;
4150 error
= user_path_at(olddfd
, oldname
, how
, &old_path
);
4154 new_dentry
= user_path_create(newdfd
, newname
, &new_path
,
4155 (how
& LOOKUP_REVAL
));
4156 error
= PTR_ERR(new_dentry
);
4157 if (IS_ERR(new_dentry
))
4161 if (old_path
.mnt
!= new_path
.mnt
)
4163 error
= may_linkat(&old_path
);
4164 if (unlikely(error
))
4166 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
4169 error
= vfs_link2(old_path
.mnt
, old_path
.dentry
, new_path
.dentry
->d_inode
, new_dentry
, &delegated_inode
);
4171 done_path_create(&new_path
, new_dentry
);
4172 if (delegated_inode
) {
4173 error
= break_deleg_wait(&delegated_inode
);
4175 path_put(&old_path
);
4179 if (retry_estale(error
, how
)) {
4180 path_put(&old_path
);
4181 how
|= LOOKUP_REVAL
;
4185 path_put(&old_path
);
4190 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
4192 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4196 * vfs_rename - rename a filesystem object
4197 * @old_dir: parent of source
4198 * @old_dentry: source
4199 * @new_dir: parent of destination
4200 * @new_dentry: destination
4201 * @delegated_inode: returns an inode needing a delegation break
4202 * @flags: rename flags
4204 * The caller must hold multiple mutexes--see lock_rename()).
4206 * If vfs_rename discovers a delegation in need of breaking at either
4207 * the source or destination, it will return -EWOULDBLOCK and return a
4208 * reference to the inode in delegated_inode. The caller should then
4209 * break the delegation and retry. Because breaking a delegation may
4210 * take a long time, the caller should drop all locks before doing
4213 * Alternatively, a caller may pass NULL for delegated_inode. This may
4214 * be appropriate for callers that expect the underlying filesystem not
4215 * to be NFS exported.
4217 * The worst of all namespace operations - renaming directory. "Perverted"
4218 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4220 * a) we can get into loop creation.
4221 * b) race potential - two innocent renames can create a loop together.
4222 * That's where 4.4 screws up. Current fix: serialization on
4223 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
4225 * c) we have to lock _four_ objects - parents and victim (if it exists),
4226 * and source (if it is not a directory).
4227 * And that - after we got ->i_mutex on parents (until then we don't know
4228 * whether the target exists). Solution: try to be smart with locking
4229 * order for inodes. We rely on the fact that tree topology may change
4230 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
4231 * move will be locked. Thus we can rank directories by the tree
4232 * (ancestors first) and rank all non-directories after them.
4233 * That works since everybody except rename does "lock parent, lookup,
4234 * lock child" and rename is under ->s_vfs_rename_mutex.
4235 * HOWEVER, it relies on the assumption that any object with ->lookup()
4236 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4237 * we'd better make sure that there's no link(2) for them.
4238 * d) conversion from fhandle to dentry may come in the wrong moment - when
4239 * we are removing the target. Solution: we will have to grab ->i_mutex
4240 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
4241 * ->i_mutex on parents, which works but leads to some truly excessive
4244 int vfs_rename2(struct vfsmount
*mnt
,
4245 struct inode
*old_dir
, struct dentry
*old_dentry
,
4246 struct inode
*new_dir
, struct dentry
*new_dentry
,
4247 struct inode
**delegated_inode
, unsigned int flags
)
4250 bool is_dir
= d_is_dir(old_dentry
);
4251 struct inode
*source
= old_dentry
->d_inode
;
4252 struct inode
*target
= new_dentry
->d_inode
;
4253 bool new_is_dir
= false;
4254 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
4255 struct name_snapshot old_name
;
4258 * Check source == target.
4259 * On overlayfs need to look at underlying inodes.
4261 if (vfs_select_inode(old_dentry
, 0) == vfs_select_inode(new_dentry
, 0))
4264 error
= may_delete(mnt
, old_dir
, old_dentry
, is_dir
);
4269 error
= may_create(mnt
, new_dir
, new_dentry
);
4271 new_is_dir
= d_is_dir(new_dentry
);
4273 if (!(flags
& RENAME_EXCHANGE
))
4274 error
= may_delete(mnt
, new_dir
, new_dentry
, is_dir
);
4276 error
= may_delete(mnt
, new_dir
, new_dentry
, new_is_dir
);
4281 if (!old_dir
->i_op
->rename
&& !old_dir
->i_op
->rename2
)
4284 if (flags
&& !old_dir
->i_op
->rename2
)
4288 * If we are going to change the parent - check write permissions,
4289 * we'll need to flip '..'.
4291 if (new_dir
!= old_dir
) {
4293 error
= inode_permission2(mnt
, source
, MAY_WRITE
);
4297 if ((flags
& RENAME_EXCHANGE
) && new_is_dir
) {
4298 error
= inode_permission2(mnt
, target
, MAY_WRITE
);
4304 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
,
4309 take_dentry_name_snapshot(&old_name
, old_dentry
);
4311 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4312 lock_two_nondirectories(source
, target
);
4314 mutex_lock(&target
->i_mutex
);
4317 if (is_local_mountpoint(old_dentry
) || is_local_mountpoint(new_dentry
))
4320 if (max_links
&& new_dir
!= old_dir
) {
4322 if (is_dir
&& !new_is_dir
&& new_dir
->i_nlink
>= max_links
)
4324 if ((flags
& RENAME_EXCHANGE
) && !is_dir
&& new_is_dir
&&
4325 old_dir
->i_nlink
>= max_links
)
4328 if (is_dir
&& !(flags
& RENAME_EXCHANGE
) && target
)
4329 shrink_dcache_parent(new_dentry
);
4331 error
= try_break_deleg(source
, delegated_inode
);
4335 if (target
&& !new_is_dir
) {
4336 error
= try_break_deleg(target
, delegated_inode
);
4340 if (!old_dir
->i_op
->rename2
) {
4341 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
,
4342 new_dir
, new_dentry
);
4344 WARN_ON(old_dir
->i_op
->rename
!= NULL
);
4345 error
= old_dir
->i_op
->rename2(old_dir
, old_dentry
,
4346 new_dir
, new_dentry
, flags
);
4351 if (!(flags
& RENAME_EXCHANGE
) && target
) {
4353 target
->i_flags
|= S_DEAD
;
4354 dont_mount(new_dentry
);
4355 detach_mounts(new_dentry
);
4357 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
)) {
4358 if (!(flags
& RENAME_EXCHANGE
))
4359 d_move(old_dentry
, new_dentry
);
4361 d_exchange(old_dentry
, new_dentry
);
4364 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4365 unlock_two_nondirectories(source
, target
);
4367 mutex_unlock(&target
->i_mutex
);
4370 fsnotify_move(old_dir
, new_dir
, old_name
.name
, is_dir
,
4371 !(flags
& RENAME_EXCHANGE
) ? target
: NULL
, old_dentry
);
4372 if (flags
& RENAME_EXCHANGE
) {
4373 fsnotify_move(new_dir
, old_dir
, old_dentry
->d_name
.name
,
4374 new_is_dir
, NULL
, new_dentry
);
4377 release_dentry_name_snapshot(&old_name
);
4381 EXPORT_SYMBOL(vfs_rename2
);
4383 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
4384 struct inode
*new_dir
, struct dentry
*new_dentry
,
4385 struct inode
**delegated_inode
, unsigned int flags
)
4387 return vfs_rename2(NULL
, old_dir
, old_dentry
, new_dir
, new_dentry
, delegated_inode
, flags
);
4389 EXPORT_SYMBOL(vfs_rename
);
4391 SYSCALL_DEFINE5(renameat2
, int, olddfd
, const char __user
*, oldname
,
4392 int, newdfd
, const char __user
*, newname
, unsigned int, flags
)
4394 struct dentry
*old_dentry
, *new_dentry
;
4395 struct dentry
*trap
;
4396 struct path old_path
, new_path
;
4397 struct qstr old_last
, new_last
;
4398 int old_type
, new_type
;
4399 struct inode
*delegated_inode
= NULL
;
4400 struct filename
*from
;
4401 struct filename
*to
;
4402 unsigned int lookup_flags
= 0, target_flags
= LOOKUP_RENAME_TARGET
;
4403 bool should_retry
= false;
4406 if (flags
& ~(RENAME_NOREPLACE
| RENAME_EXCHANGE
| RENAME_WHITEOUT
))
4409 if ((flags
& (RENAME_NOREPLACE
| RENAME_WHITEOUT
)) &&
4410 (flags
& RENAME_EXCHANGE
))
4413 if ((flags
& RENAME_WHITEOUT
) && !capable(CAP_MKNOD
))
4416 if (flags
& RENAME_EXCHANGE
)
4420 from
= user_path_parent(olddfd
, oldname
,
4421 &old_path
, &old_last
, &old_type
, lookup_flags
);
4423 error
= PTR_ERR(from
);
4427 to
= user_path_parent(newdfd
, newname
,
4428 &new_path
, &new_last
, &new_type
, lookup_flags
);
4430 error
= PTR_ERR(to
);
4435 if (old_path
.mnt
!= new_path
.mnt
)
4439 if (old_type
!= LAST_NORM
)
4442 if (flags
& RENAME_NOREPLACE
)
4444 if (new_type
!= LAST_NORM
)
4447 error
= mnt_want_write(old_path
.mnt
);
4452 trap
= lock_rename(new_path
.dentry
, old_path
.dentry
);
4454 old_dentry
= __lookup_hash(&old_last
, old_path
.dentry
, lookup_flags
);
4455 error
= PTR_ERR(old_dentry
);
4456 if (IS_ERR(old_dentry
))
4458 /* source must exist */
4460 if (d_is_negative(old_dentry
))
4462 new_dentry
= __lookup_hash(&new_last
, new_path
.dentry
, lookup_flags
| target_flags
);
4463 error
= PTR_ERR(new_dentry
);
4464 if (IS_ERR(new_dentry
))
4467 if ((flags
& RENAME_NOREPLACE
) && d_is_positive(new_dentry
))
4469 if (flags
& RENAME_EXCHANGE
) {
4471 if (d_is_negative(new_dentry
))
4474 if (!d_is_dir(new_dentry
)) {
4476 if (new_last
.name
[new_last
.len
])
4480 /* unless the source is a directory trailing slashes give -ENOTDIR */
4481 if (!d_is_dir(old_dentry
)) {
4483 if (old_last
.name
[old_last
.len
])
4485 if (!(flags
& RENAME_EXCHANGE
) && new_last
.name
[new_last
.len
])
4488 /* source should not be ancestor of target */
4490 if (old_dentry
== trap
)
4492 /* target should not be an ancestor of source */
4493 if (!(flags
& RENAME_EXCHANGE
))
4495 if (new_dentry
== trap
)
4498 error
= security_path_rename(&old_path
, old_dentry
,
4499 &new_path
, new_dentry
, flags
);
4502 error
= vfs_rename2(old_path
.mnt
, old_path
.dentry
->d_inode
, old_dentry
,
4503 new_path
.dentry
->d_inode
, new_dentry
,
4504 &delegated_inode
, flags
);
4510 unlock_rename(new_path
.dentry
, old_path
.dentry
);
4511 if (delegated_inode
) {
4512 error
= break_deleg_wait(&delegated_inode
);
4516 mnt_drop_write(old_path
.mnt
);
4518 if (retry_estale(error
, lookup_flags
))
4519 should_retry
= true;
4520 path_put(&new_path
);
4523 path_put(&old_path
);
4526 should_retry
= false;
4527 lookup_flags
|= LOOKUP_REVAL
;
4534 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
4535 int, newdfd
, const char __user
*, newname
)
4537 return sys_renameat2(olddfd
, oldname
, newdfd
, newname
, 0);
4540 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
4542 return sys_renameat2(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4545 int vfs_whiteout(struct inode
*dir
, struct dentry
*dentry
)
4547 int error
= may_create(NULL
, dir
, dentry
);
4551 if (!dir
->i_op
->mknod
)
4554 return dir
->i_op
->mknod(dir
, dentry
,
4555 S_IFCHR
| WHITEOUT_MODE
, WHITEOUT_DEV
);
4557 EXPORT_SYMBOL(vfs_whiteout
);
4559 int readlink_copy(char __user
*buffer
, int buflen
, const char *link
)
4561 int len
= PTR_ERR(link
);
4566 if (len
> (unsigned) buflen
)
4568 if (copy_to_user(buffer
, link
, len
))
4573 EXPORT_SYMBOL(readlink_copy
);
4576 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
4577 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
4578 * using) it for any given inode is up to filesystem.
4580 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4583 struct inode
*inode
= d_inode(dentry
);
4584 const char *link
= inode
->i_link
;
4588 link
= inode
->i_op
->follow_link(dentry
, &cookie
);
4590 return PTR_ERR(link
);
4592 res
= readlink_copy(buffer
, buflen
, link
);
4593 if (inode
->i_op
->put_link
)
4594 inode
->i_op
->put_link(inode
, cookie
);
4597 EXPORT_SYMBOL(generic_readlink
);
4599 /* get the link contents into pagecache */
4600 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
4604 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
4605 page
= read_mapping_page(mapping
, 0, NULL
);
4610 nd_terminate_link(kaddr
, dentry
->d_inode
->i_size
, PAGE_SIZE
- 1);
4614 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4616 struct page
*page
= NULL
;
4617 int res
= readlink_copy(buffer
, buflen
, page_getlink(dentry
, &page
));
4620 page_cache_release(page
);
4624 EXPORT_SYMBOL(page_readlink
);
4626 const char *page_follow_link_light(struct dentry
*dentry
, void **cookie
)
4628 struct page
*page
= NULL
;
4629 char *res
= page_getlink(dentry
, &page
);
4634 EXPORT_SYMBOL(page_follow_link_light
);
4636 void page_put_link(struct inode
*unused
, void *cookie
)
4638 struct page
*page
= cookie
;
4640 page_cache_release(page
);
4642 EXPORT_SYMBOL(page_put_link
);
4645 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
4647 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
4649 struct address_space
*mapping
= inode
->i_mapping
;
4654 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
4656 flags
|= AOP_FLAG_NOFS
;
4659 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
4660 flags
, &page
, &fsdata
);
4664 kaddr
= kmap_atomic(page
);
4665 memcpy(kaddr
, symname
, len
-1);
4666 kunmap_atomic(kaddr
);
4668 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
4675 mark_inode_dirty(inode
);
4680 EXPORT_SYMBOL(__page_symlink
);
4682 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
4684 return __page_symlink(inode
, symname
, len
,
4685 !mapping_gfp_constraint(inode
->i_mapping
, __GFP_FS
));
4687 EXPORT_SYMBOL(page_symlink
);
4689 const struct inode_operations page_symlink_inode_operations
= {
4690 .readlink
= generic_readlink
,
4691 .follow_link
= page_follow_link_light
,
4692 .put_link
= page_put_link
,
4694 EXPORT_SYMBOL(page_symlink_inode_operations
);