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 <linux/bitops.h>
39 #include <linux/init_task.h>
40 #include <linux/uaccess.h>
45 /* [Feb-1997 T. Schoebel-Theuer]
46 * Fundamental changes in the pathname lookup mechanisms (namei)
47 * were necessary because of omirr. The reason is that omirr needs
48 * to know the _real_ pathname, not the user-supplied one, in case
49 * of symlinks (and also when transname replacements occur).
51 * The new code replaces the old recursive symlink resolution with
52 * an iterative one (in case of non-nested symlink chains). It does
53 * this with calls to <fs>_follow_link().
54 * As a side effect, dir_namei(), _namei() and follow_link() are now
55 * replaced with a single function lookup_dentry() that can handle all
56 * the special cases of the former code.
58 * With the new dcache, the pathname is stored at each inode, at least as
59 * long as the refcount of the inode is positive. As a side effect, the
60 * size of the dcache depends on the inode cache and thus is dynamic.
62 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
63 * resolution to correspond with current state of the code.
65 * Note that the symlink resolution is not *completely* iterative.
66 * There is still a significant amount of tail- and mid- recursion in
67 * the algorithm. Also, note that <fs>_readlink() is not used in
68 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
69 * may return different results than <fs>_follow_link(). Many virtual
70 * filesystems (including /proc) exhibit this behavior.
73 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
74 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
75 * and the name already exists in form of a symlink, try to create the new
76 * name indicated by the symlink. The old code always complained that the
77 * name already exists, due to not following the symlink even if its target
78 * is nonexistent. The new semantics affects also mknod() and link() when
79 * the name is a symlink pointing to a non-existent name.
81 * I don't know which semantics is the right one, since I have no access
82 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
83 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
84 * "old" one. Personally, I think the new semantics is much more logical.
85 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
86 * file does succeed in both HP-UX and SunOs, but not in Solaris
87 * and in the old Linux semantics.
90 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
91 * semantics. See the comments in "open_namei" and "do_link" below.
93 * [10-Sep-98 Alan Modra] Another symlink change.
96 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
97 * inside the path - always follow.
98 * in the last component in creation/removal/renaming - never follow.
99 * if LOOKUP_FOLLOW passed - follow.
100 * if the pathname has trailing slashes - follow.
101 * otherwise - don't follow.
102 * (applied in that order).
104 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
105 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
106 * During the 2.4 we need to fix the userland stuff depending on it -
107 * hopefully we will be able to get rid of that wart in 2.5. So far only
108 * XEmacs seems to be relying on it...
111 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
112 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
113 * any extra contention...
116 /* In order to reduce some races, while at the same time doing additional
117 * checking and hopefully speeding things up, we copy filenames to the
118 * kernel data space before using them..
120 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
121 * PATH_MAX includes the nul terminator --RR.
124 #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname))
127 getname_flags(const char __user
*filename
, int flags
, int *empty
)
129 struct filename
*result
;
133 result
= audit_reusename(filename
);
137 result
= __getname();
138 if (unlikely(!result
))
139 return ERR_PTR(-ENOMEM
);
142 * First, try to embed the struct filename inside the names_cache
145 kname
= (char *)result
->iname
;
146 result
->name
= kname
;
148 len
= strncpy_from_user(kname
, filename
, EMBEDDED_NAME_MAX
);
149 if (unlikely(len
< 0)) {
155 * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
156 * separate struct filename so we can dedicate the entire
157 * names_cache allocation for the pathname, and re-do the copy from
160 if (unlikely(len
== EMBEDDED_NAME_MAX
)) {
161 const size_t size
= offsetof(struct filename
, iname
[1]);
162 kname
= (char *)result
;
165 * size is chosen that way we to guarantee that
166 * result->iname[0] is within the same object and that
167 * kname can't be equal to result->iname, no matter what.
169 result
= kzalloc(size
, GFP_KERNEL
);
170 if (unlikely(!result
)) {
172 return ERR_PTR(-ENOMEM
);
174 result
->name
= kname
;
175 len
= strncpy_from_user(kname
, filename
, PATH_MAX
);
176 if (unlikely(len
< 0)) {
181 if (unlikely(len
== PATH_MAX
)) {
184 return ERR_PTR(-ENAMETOOLONG
);
189 /* The empty path is special. */
190 if (unlikely(!len
)) {
193 if (!(flags
& LOOKUP_EMPTY
)) {
195 return ERR_PTR(-ENOENT
);
199 result
->uptr
= filename
;
200 result
->aname
= NULL
;
201 audit_getname(result
);
206 getname(const char __user
* filename
)
208 return getname_flags(filename
, 0, NULL
);
212 getname_kernel(const char * filename
)
214 struct filename
*result
;
215 int len
= strlen(filename
) + 1;
217 result
= __getname();
218 if (unlikely(!result
))
219 return ERR_PTR(-ENOMEM
);
221 if (len
<= EMBEDDED_NAME_MAX
) {
222 result
->name
= (char *)result
->iname
;
223 } else if (len
<= PATH_MAX
) {
224 struct filename
*tmp
;
226 tmp
= kmalloc(sizeof(*tmp
), GFP_KERNEL
);
227 if (unlikely(!tmp
)) {
229 return ERR_PTR(-ENOMEM
);
231 tmp
->name
= (char *)result
;
235 return ERR_PTR(-ENAMETOOLONG
);
237 memcpy((char *)result
->name
, filename
, len
);
239 result
->aname
= NULL
;
241 audit_getname(result
);
246 void putname(struct filename
*name
)
248 BUG_ON(name
->refcnt
<= 0);
250 if (--name
->refcnt
> 0)
253 if (name
->name
!= name
->iname
) {
254 __putname(name
->name
);
260 static int check_acl(struct inode
*inode
, int mask
)
262 #ifdef CONFIG_FS_POSIX_ACL
263 struct posix_acl
*acl
;
265 if (mask
& MAY_NOT_BLOCK
) {
266 acl
= get_cached_acl_rcu(inode
, ACL_TYPE_ACCESS
);
269 /* no ->get_acl() calls in RCU mode... */
270 if (is_uncached_acl(acl
))
272 return posix_acl_permission(inode
, acl
, mask
& ~MAY_NOT_BLOCK
);
275 acl
= get_acl(inode
, ACL_TYPE_ACCESS
);
279 int error
= posix_acl_permission(inode
, acl
, mask
);
280 posix_acl_release(acl
);
289 * This does the basic permission checking
291 static int acl_permission_check(struct inode
*inode
, int mask
)
293 unsigned int mode
= inode
->i_mode
;
295 if (likely(uid_eq(current_fsuid(), inode
->i_uid
)))
298 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
)) {
299 int error
= check_acl(inode
, mask
);
300 if (error
!= -EAGAIN
)
304 if (in_group_p(inode
->i_gid
))
309 * If the DACs are ok we don't need any capability check.
311 if ((mask
& ~mode
& (MAY_READ
| MAY_WRITE
| MAY_EXEC
)) == 0)
317 * generic_permission - check for access rights on a Posix-like filesystem
318 * @inode: inode to check access rights for
319 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
321 * Used to check for read/write/execute permissions on a file.
322 * We use "fsuid" for this, letting us set arbitrary permissions
323 * for filesystem access without changing the "normal" uids which
324 * are used for other things.
326 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
327 * request cannot be satisfied (eg. requires blocking or too much complexity).
328 * It would then be called again in ref-walk mode.
330 int generic_permission(struct inode
*inode
, int mask
)
335 * Do the basic permission checks.
337 ret
= acl_permission_check(inode
, mask
);
341 if (S_ISDIR(inode
->i_mode
)) {
342 /* DACs are overridable for directories */
343 if (!(mask
& MAY_WRITE
))
344 if (capable_wrt_inode_uidgid(inode
,
345 CAP_DAC_READ_SEARCH
))
347 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_OVERRIDE
))
353 * Searching includes executable on directories, else just read.
355 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
356 if (mask
== MAY_READ
)
357 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_READ_SEARCH
))
360 * Read/write DACs are always overridable.
361 * Executable DACs are overridable when there is
362 * at least one exec bit set.
364 if (!(mask
& MAY_EXEC
) || (inode
->i_mode
& S_IXUGO
))
365 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_OVERRIDE
))
370 EXPORT_SYMBOL(generic_permission
);
373 * We _really_ want to just do "generic_permission()" without
374 * even looking at the inode->i_op values. So we keep a cache
375 * flag in inode->i_opflags, that says "this has not special
376 * permission function, use the fast case".
378 static inline int do_inode_permission(struct inode
*inode
, int mask
)
380 if (unlikely(!(inode
->i_opflags
& IOP_FASTPERM
))) {
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_permission(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 * Updating mtime will likely cause i_uid and i_gid to be
417 * written back improperly if their true value is unknown
420 if (HAS_UNMAPPED_ID(inode
))
424 retval
= do_inode_permission(inode
, mask
);
428 retval
= devcgroup_inode_permission(inode
, mask
);
432 return security_inode_permission(inode
, mask
);
434 EXPORT_SYMBOL(__inode_permission
);
437 * sb_permission - Check superblock-level permissions
438 * @sb: Superblock of inode to check permission on
439 * @inode: Inode to check permission on
440 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
442 * Separate out file-system wide checks from inode-specific permission checks.
444 static int sb_permission(struct super_block
*sb
, struct inode
*inode
, int mask
)
446 if (unlikely(mask
& MAY_WRITE
)) {
447 umode_t mode
= inode
->i_mode
;
449 /* Nobody gets write access to a read-only fs. */
450 if (sb_rdonly(sb
) && (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_permission(struct inode
*inode
, int mask
)
471 retval
= sb_permission(inode
->i_sb
, inode
, mask
);
474 return __inode_permission(inode
, mask
);
476 EXPORT_SYMBOL(inode_permission
);
479 * path_get - get a reference to a path
480 * @path: path to get the reference to
482 * Given a path increment the reference count to the dentry and the vfsmount.
484 void path_get(const struct path
*path
)
489 EXPORT_SYMBOL(path_get
);
492 * path_put - put a reference to a path
493 * @path: path to put the reference to
495 * Given a path decrement the reference count to the dentry and the vfsmount.
497 void path_put(const struct path
*path
)
502 EXPORT_SYMBOL(path_put
);
504 #define EMBEDDED_LEVELS 2
509 struct inode
*inode
; /* path.dentry.d_inode */
514 int total_link_count
;
517 struct delayed_call done
;
520 } *stack
, internal
[EMBEDDED_LEVELS
];
521 struct filename
*name
;
522 struct nameidata
*saved
;
523 struct inode
*link_inode
;
526 } __randomize_layout
;
528 static void set_nameidata(struct nameidata
*p
, int dfd
, struct filename
*name
)
530 struct nameidata
*old
= current
->nameidata
;
531 p
->stack
= p
->internal
;
534 p
->total_link_count
= old
? old
->total_link_count
: 0;
536 current
->nameidata
= p
;
539 static void restore_nameidata(void)
541 struct nameidata
*now
= current
->nameidata
, *old
= now
->saved
;
543 current
->nameidata
= old
;
545 old
->total_link_count
= now
->total_link_count
;
546 if (now
->stack
!= now
->internal
)
550 static int __nd_alloc_stack(struct nameidata
*nd
)
554 if (nd
->flags
& LOOKUP_RCU
) {
555 p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
560 p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
565 memcpy(p
, nd
->internal
, sizeof(nd
->internal
));
571 * path_connected - Verify that a path->dentry is below path->mnt.mnt_root
572 * @path: nameidate to verify
574 * Rename can sometimes move a file or directory outside of a bind
575 * mount, path_connected allows those cases to be detected.
577 static bool path_connected(const struct path
*path
)
579 struct vfsmount
*mnt
= path
->mnt
;
581 /* Only bind mounts can have disconnected paths */
582 if (mnt
->mnt_root
== mnt
->mnt_sb
->s_root
)
585 return is_subdir(path
->dentry
, mnt
->mnt_root
);
588 static inline int nd_alloc_stack(struct nameidata
*nd
)
590 if (likely(nd
->depth
!= EMBEDDED_LEVELS
))
592 if (likely(nd
->stack
!= nd
->internal
))
594 return __nd_alloc_stack(nd
);
597 static void drop_links(struct nameidata
*nd
)
601 struct saved
*last
= nd
->stack
+ i
;
602 do_delayed_call(&last
->done
);
603 clear_delayed_call(&last
->done
);
607 static void terminate_walk(struct nameidata
*nd
)
610 if (!(nd
->flags
& LOOKUP_RCU
)) {
613 for (i
= 0; i
< nd
->depth
; i
++)
614 path_put(&nd
->stack
[i
].link
);
615 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
620 nd
->flags
&= ~LOOKUP_RCU
;
621 if (!(nd
->flags
& LOOKUP_ROOT
))
628 /* path_put is needed afterwards regardless of success or failure */
629 static bool legitimize_path(struct nameidata
*nd
,
630 struct path
*path
, unsigned seq
)
632 int res
= __legitimize_mnt(path
->mnt
, nd
->m_seq
);
639 if (unlikely(!lockref_get_not_dead(&path
->dentry
->d_lockref
))) {
643 return !read_seqcount_retry(&path
->dentry
->d_seq
, seq
);
646 static bool legitimize_links(struct nameidata
*nd
)
649 for (i
= 0; i
< nd
->depth
; i
++) {
650 struct saved
*last
= nd
->stack
+ i
;
651 if (unlikely(!legitimize_path(nd
, &last
->link
, last
->seq
))) {
661 * Path walking has 2 modes, rcu-walk and ref-walk (see
662 * Documentation/filesystems/path-lookup.txt). In situations when we can't
663 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
664 * normal reference counts on dentries and vfsmounts to transition to ref-walk
665 * mode. Refcounts are grabbed at the last known good point before rcu-walk
666 * got stuck, so ref-walk may continue from there. If this is not successful
667 * (eg. a seqcount has changed), then failure is returned and it's up to caller
668 * to restart the path walk from the beginning in ref-walk mode.
672 * unlazy_walk - try to switch to ref-walk mode.
673 * @nd: nameidata pathwalk data
674 * Returns: 0 on success, -ECHILD on failure
676 * unlazy_walk attempts to legitimize the current nd->path and nd->root
678 * Must be called from rcu-walk context.
679 * Nothing should touch nameidata between unlazy_walk() failure and
682 static int unlazy_walk(struct nameidata
*nd
)
684 struct dentry
*parent
= nd
->path
.dentry
;
686 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
688 nd
->flags
&= ~LOOKUP_RCU
;
689 if (unlikely(!legitimize_links(nd
)))
691 if (unlikely(!legitimize_path(nd
, &nd
->path
, nd
->seq
)))
693 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
694 if (unlikely(!legitimize_path(nd
, &nd
->root
, nd
->root_seq
)))
698 BUG_ON(nd
->inode
!= parent
->d_inode
);
703 nd
->path
.dentry
= NULL
;
705 if (!(nd
->flags
& LOOKUP_ROOT
))
713 * unlazy_child - try to switch to ref-walk mode.
714 * @nd: nameidata pathwalk data
715 * @dentry: child of nd->path.dentry
716 * @seq: seq number to check dentry against
717 * Returns: 0 on success, -ECHILD on failure
719 * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry
720 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
721 * @nd. Must be called from rcu-walk context.
722 * Nothing should touch nameidata between unlazy_child() failure and
725 static int unlazy_child(struct nameidata
*nd
, struct dentry
*dentry
, unsigned seq
)
727 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
729 nd
->flags
&= ~LOOKUP_RCU
;
730 if (unlikely(!legitimize_links(nd
)))
732 if (unlikely(!legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
)))
734 if (unlikely(!lockref_get_not_dead(&nd
->path
.dentry
->d_lockref
)))
738 * We need to move both the parent and the dentry from the RCU domain
739 * to be properly refcounted. And the sequence number in the dentry
740 * validates *both* dentry counters, since we checked the sequence
741 * number of the parent after we got the child sequence number. So we
742 * know the parent must still be valid if the child sequence number is
744 if (unlikely(!lockref_get_not_dead(&dentry
->d_lockref
)))
746 if (unlikely(read_seqcount_retry(&dentry
->d_seq
, seq
))) {
752 * Sequence counts matched. Now make sure that the root is
753 * still valid and get it if required.
755 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
756 if (unlikely(!legitimize_path(nd
, &nd
->root
, nd
->root_seq
))) {
769 nd
->path
.dentry
= NULL
;
773 if (!(nd
->flags
& LOOKUP_ROOT
))
778 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
780 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
))
781 return dentry
->d_op
->d_revalidate(dentry
, flags
);
787 * complete_walk - successful completion of path walk
788 * @nd: pointer nameidata
790 * If we had been in RCU mode, drop out of it and legitimize nd->path.
791 * Revalidate the final result, unless we'd already done that during
792 * the path walk or the filesystem doesn't ask for it. Return 0 on
793 * success, -error on failure. In case of failure caller does not
794 * need to drop nd->path.
796 static int complete_walk(struct nameidata
*nd
)
798 struct dentry
*dentry
= nd
->path
.dentry
;
801 if (nd
->flags
& LOOKUP_RCU
) {
802 if (!(nd
->flags
& LOOKUP_ROOT
))
804 if (unlikely(unlazy_walk(nd
)))
808 if (likely(!(nd
->flags
& LOOKUP_JUMPED
)))
811 if (likely(!(dentry
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)))
814 status
= dentry
->d_op
->d_weak_revalidate(dentry
, nd
->flags
);
824 static void set_root(struct nameidata
*nd
)
826 struct fs_struct
*fs
= current
->fs
;
828 if (nd
->flags
& LOOKUP_RCU
) {
832 seq
= read_seqcount_begin(&fs
->seq
);
834 nd
->root_seq
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
835 } while (read_seqcount_retry(&fs
->seq
, seq
));
837 get_fs_root(fs
, &nd
->root
);
841 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
844 if (path
->mnt
!= nd
->path
.mnt
)
848 static inline void path_to_nameidata(const struct path
*path
,
849 struct nameidata
*nd
)
851 if (!(nd
->flags
& LOOKUP_RCU
)) {
852 dput(nd
->path
.dentry
);
853 if (nd
->path
.mnt
!= path
->mnt
)
854 mntput(nd
->path
.mnt
);
856 nd
->path
.mnt
= path
->mnt
;
857 nd
->path
.dentry
= path
->dentry
;
860 static int nd_jump_root(struct nameidata
*nd
)
862 if (nd
->flags
& LOOKUP_RCU
) {
866 nd
->inode
= d
->d_inode
;
867 nd
->seq
= nd
->root_seq
;
868 if (unlikely(read_seqcount_retry(&d
->d_seq
, nd
->seq
)))
874 nd
->inode
= nd
->path
.dentry
->d_inode
;
876 nd
->flags
|= LOOKUP_JUMPED
;
881 * Helper to directly jump to a known parsed path from ->get_link,
882 * caller must have taken a reference to path beforehand.
884 void nd_jump_link(struct path
*path
)
886 struct nameidata
*nd
= current
->nameidata
;
890 nd
->inode
= nd
->path
.dentry
->d_inode
;
891 nd
->flags
|= LOOKUP_JUMPED
;
894 static inline void put_link(struct nameidata
*nd
)
896 struct saved
*last
= nd
->stack
+ --nd
->depth
;
897 do_delayed_call(&last
->done
);
898 if (!(nd
->flags
& LOOKUP_RCU
))
899 path_put(&last
->link
);
902 int sysctl_protected_symlinks __read_mostly
= 0;
903 int sysctl_protected_hardlinks __read_mostly
= 0;
906 * may_follow_link - Check symlink following for unsafe situations
907 * @nd: nameidata pathwalk data
909 * In the case of the sysctl_protected_symlinks sysctl being enabled,
910 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
911 * in a sticky world-writable directory. This is to protect privileged
912 * processes from failing races against path names that may change out
913 * from under them by way of other users creating malicious symlinks.
914 * It will permit symlinks to be followed only when outside a sticky
915 * world-writable directory, or when the uid of the symlink and follower
916 * match, or when the directory owner matches the symlink's owner.
918 * Returns 0 if following the symlink is allowed, -ve on error.
920 static inline int may_follow_link(struct nameidata
*nd
)
922 const struct inode
*inode
;
923 const struct inode
*parent
;
926 if (!sysctl_protected_symlinks
)
929 /* Allowed if owner and follower match. */
930 inode
= nd
->link_inode
;
931 if (uid_eq(current_cred()->fsuid
, inode
->i_uid
))
934 /* Allowed if parent directory not sticky and world-writable. */
936 if ((parent
->i_mode
& (S_ISVTX
|S_IWOTH
)) != (S_ISVTX
|S_IWOTH
))
939 /* Allowed if parent directory and link owner match. */
940 puid
= parent
->i_uid
;
941 if (uid_valid(puid
) && uid_eq(puid
, inode
->i_uid
))
944 if (nd
->flags
& LOOKUP_RCU
)
947 audit_log_link_denied("follow_link", &nd
->stack
[0].link
);
952 * safe_hardlink_source - Check for safe hardlink conditions
953 * @inode: the source inode to hardlink from
955 * Return false if at least one of the following conditions:
956 * - inode is not a regular file
958 * - inode is setgid and group-exec
959 * - access failure for read and write
961 * Otherwise returns true.
963 static bool safe_hardlink_source(struct inode
*inode
)
965 umode_t mode
= inode
->i_mode
;
967 /* Special files should not get pinned to the filesystem. */
971 /* Setuid files should not get pinned to the filesystem. */
975 /* Executable setgid files should not get pinned to the filesystem. */
976 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
))
979 /* Hardlinking to unreadable or unwritable sources is dangerous. */
980 if (inode_permission(inode
, MAY_READ
| MAY_WRITE
))
987 * may_linkat - Check permissions for creating a hardlink
988 * @link: the source to hardlink from
990 * Block hardlink when all of:
991 * - sysctl_protected_hardlinks enabled
992 * - fsuid does not match inode
993 * - hardlink source is unsafe (see safe_hardlink_source() above)
994 * - not CAP_FOWNER in a namespace with the inode owner uid mapped
996 * Returns 0 if successful, -ve on error.
998 static int may_linkat(struct path
*link
)
1000 struct inode
*inode
;
1002 if (!sysctl_protected_hardlinks
)
1005 inode
= link
->dentry
->d_inode
;
1007 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
1008 * otherwise, it must be a safe source.
1010 if (safe_hardlink_source(inode
) || inode_owner_or_capable(inode
))
1013 audit_log_link_denied("linkat", link
);
1017 static __always_inline
1018 const char *get_link(struct nameidata
*nd
)
1020 struct saved
*last
= nd
->stack
+ nd
->depth
- 1;
1021 struct dentry
*dentry
= last
->link
.dentry
;
1022 struct inode
*inode
= nd
->link_inode
;
1026 if (!(nd
->flags
& LOOKUP_RCU
)) {
1027 touch_atime(&last
->link
);
1029 } else if (atime_needs_update_rcu(&last
->link
, inode
)) {
1030 if (unlikely(unlazy_walk(nd
)))
1031 return ERR_PTR(-ECHILD
);
1032 touch_atime(&last
->link
);
1035 error
= security_inode_follow_link(dentry
, inode
,
1036 nd
->flags
& LOOKUP_RCU
);
1037 if (unlikely(error
))
1038 return ERR_PTR(error
);
1040 nd
->last_type
= LAST_BIND
;
1041 res
= inode
->i_link
;
1043 const char * (*get
)(struct dentry
*, struct inode
*,
1044 struct delayed_call
*);
1045 get
= inode
->i_op
->get_link
;
1046 if (nd
->flags
& LOOKUP_RCU
) {
1047 res
= get(NULL
, inode
, &last
->done
);
1048 if (res
== ERR_PTR(-ECHILD
)) {
1049 if (unlikely(unlazy_walk(nd
)))
1050 return ERR_PTR(-ECHILD
);
1051 res
= get(dentry
, inode
, &last
->done
);
1054 res
= get(dentry
, inode
, &last
->done
);
1056 if (IS_ERR_OR_NULL(res
))
1062 if (unlikely(nd_jump_root(nd
)))
1063 return ERR_PTR(-ECHILD
);
1064 while (unlikely(*++res
== '/'))
1073 * follow_up - Find the mountpoint of path's vfsmount
1075 * Given a path, find the mountpoint of its source file system.
1076 * Replace @path with the path of the mountpoint in the parent mount.
1079 * Return 1 if we went up a level and 0 if we were already at the
1082 int follow_up(struct path
*path
)
1084 struct mount
*mnt
= real_mount(path
->mnt
);
1085 struct mount
*parent
;
1086 struct dentry
*mountpoint
;
1088 read_seqlock_excl(&mount_lock
);
1089 parent
= mnt
->mnt_parent
;
1090 if (parent
== mnt
) {
1091 read_sequnlock_excl(&mount_lock
);
1094 mntget(&parent
->mnt
);
1095 mountpoint
= dget(mnt
->mnt_mountpoint
);
1096 read_sequnlock_excl(&mount_lock
);
1098 path
->dentry
= mountpoint
;
1100 path
->mnt
= &parent
->mnt
;
1103 EXPORT_SYMBOL(follow_up
);
1106 * Perform an automount
1107 * - return -EISDIR to tell follow_managed() to stop and return the path we
1110 static int follow_automount(struct path
*path
, struct nameidata
*nd
,
1113 struct vfsmount
*mnt
;
1116 if (!path
->dentry
->d_op
|| !path
->dentry
->d_op
->d_automount
)
1119 /* We don't want to mount if someone's just doing a stat -
1120 * unless they're stat'ing a directory and appended a '/' to
1123 * We do, however, want to mount if someone wants to open or
1124 * create a file of any type under the mountpoint, wants to
1125 * traverse through the mountpoint or wants to open the
1126 * mounted directory. Also, autofs may mark negative dentries
1127 * as being automount points. These will need the attentions
1128 * of the daemon to instantiate them before they can be used.
1130 if (!(nd
->flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
1131 LOOKUP_OPEN
| LOOKUP_CREATE
|
1132 LOOKUP_AUTOMOUNT
))) {
1133 /* Positive dentry that isn't meant to trigger an
1134 * automount, EISDIR will allow it to be used,
1135 * otherwise there's no mount here "now" so return
1138 if (path
->dentry
->d_inode
)
1144 if (path
->dentry
->d_sb
->s_user_ns
!= &init_user_ns
)
1147 nd
->total_link_count
++;
1148 if (nd
->total_link_count
>= 40)
1151 mnt
= path
->dentry
->d_op
->d_automount(path
);
1154 * The filesystem is allowed to return -EISDIR here to indicate
1155 * it doesn't want to automount. For instance, autofs would do
1156 * this so that its userspace daemon can mount on this dentry.
1158 * However, we can only permit this if it's a terminal point in
1159 * the path being looked up; if it wasn't then the remainder of
1160 * the path is inaccessible and we should say so.
1162 if (PTR_ERR(mnt
) == -EISDIR
&& (nd
->flags
& LOOKUP_PARENT
))
1164 return PTR_ERR(mnt
);
1167 if (!mnt
) /* mount collision */
1170 if (!*need_mntput
) {
1171 /* lock_mount() may release path->mnt on error */
1173 *need_mntput
= true;
1175 err
= finish_automount(mnt
, path
);
1179 /* Someone else made a mount here whilst we were busy */
1184 path
->dentry
= dget(mnt
->mnt_root
);
1193 * Handle a dentry that is managed in some way.
1194 * - Flagged for transit management (autofs)
1195 * - Flagged as mountpoint
1196 * - Flagged as automount point
1198 * This may only be called in refwalk mode.
1200 * Serialization is taken care of in namespace.c
1202 static int follow_managed(struct path
*path
, struct nameidata
*nd
)
1204 struct vfsmount
*mnt
= path
->mnt
; /* held by caller, must be left alone */
1206 bool need_mntput
= false;
1209 /* Given that we're not holding a lock here, we retain the value in a
1210 * local variable for each dentry as we look at it so that we don't see
1211 * the components of that value change under us */
1212 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1213 managed
&= DCACHE_MANAGED_DENTRY
,
1214 unlikely(managed
!= 0)) {
1215 /* Allow the filesystem to manage the transit without i_mutex
1217 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1218 BUG_ON(!path
->dentry
->d_op
);
1219 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1220 ret
= path
->dentry
->d_op
->d_manage(path
, false);
1225 /* Transit to a mounted filesystem. */
1226 if (managed
& DCACHE_MOUNTED
) {
1227 struct vfsmount
*mounted
= lookup_mnt(path
);
1232 path
->mnt
= mounted
;
1233 path
->dentry
= dget(mounted
->mnt_root
);
1238 /* Something is mounted on this dentry in another
1239 * namespace and/or whatever was mounted there in this
1240 * namespace got unmounted before lookup_mnt() could
1244 /* Handle an automount point */
1245 if (managed
& DCACHE_NEED_AUTOMOUNT
) {
1246 ret
= follow_automount(path
, nd
, &need_mntput
);
1252 /* We didn't change the current path point */
1256 if (need_mntput
&& path
->mnt
== mnt
)
1258 if (ret
== -EISDIR
|| !ret
)
1261 nd
->flags
|= LOOKUP_JUMPED
;
1262 if (unlikely(ret
< 0))
1263 path_put_conditional(path
, nd
);
1267 int follow_down_one(struct path
*path
)
1269 struct vfsmount
*mounted
;
1271 mounted
= lookup_mnt(path
);
1275 path
->mnt
= mounted
;
1276 path
->dentry
= dget(mounted
->mnt_root
);
1281 EXPORT_SYMBOL(follow_down_one
);
1283 static inline int managed_dentry_rcu(const struct path
*path
)
1285 return (path
->dentry
->d_flags
& DCACHE_MANAGE_TRANSIT
) ?
1286 path
->dentry
->d_op
->d_manage(path
, true) : 0;
1290 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1291 * we meet a managed dentry that would need blocking.
1293 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
,
1294 struct inode
**inode
, unsigned *seqp
)
1297 struct mount
*mounted
;
1299 * Don't forget we might have a non-mountpoint managed dentry
1300 * that wants to block transit.
1302 switch (managed_dentry_rcu(path
)) {
1312 if (!d_mountpoint(path
->dentry
))
1313 return !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1315 mounted
= __lookup_mnt(path
->mnt
, path
->dentry
);
1318 path
->mnt
= &mounted
->mnt
;
1319 path
->dentry
= mounted
->mnt
.mnt_root
;
1320 nd
->flags
|= LOOKUP_JUMPED
;
1321 *seqp
= read_seqcount_begin(&path
->dentry
->d_seq
);
1323 * Update the inode too. We don't need to re-check the
1324 * dentry sequence number here after this d_inode read,
1325 * because a mount-point is always pinned.
1327 *inode
= path
->dentry
->d_inode
;
1329 return !read_seqretry(&mount_lock
, nd
->m_seq
) &&
1330 !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1333 static int follow_dotdot_rcu(struct nameidata
*nd
)
1335 struct inode
*inode
= nd
->inode
;
1338 if (path_equal(&nd
->path
, &nd
->root
))
1340 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1341 struct dentry
*old
= nd
->path
.dentry
;
1342 struct dentry
*parent
= old
->d_parent
;
1345 inode
= parent
->d_inode
;
1346 seq
= read_seqcount_begin(&parent
->d_seq
);
1347 if (unlikely(read_seqcount_retry(&old
->d_seq
, nd
->seq
)))
1349 nd
->path
.dentry
= parent
;
1351 if (unlikely(!path_connected(&nd
->path
)))
1355 struct mount
*mnt
= real_mount(nd
->path
.mnt
);
1356 struct mount
*mparent
= mnt
->mnt_parent
;
1357 struct dentry
*mountpoint
= mnt
->mnt_mountpoint
;
1358 struct inode
*inode2
= mountpoint
->d_inode
;
1359 unsigned seq
= read_seqcount_begin(&mountpoint
->d_seq
);
1360 if (unlikely(read_seqretry(&mount_lock
, nd
->m_seq
)))
1362 if (&mparent
->mnt
== nd
->path
.mnt
)
1364 /* we know that mountpoint was pinned */
1365 nd
->path
.dentry
= mountpoint
;
1366 nd
->path
.mnt
= &mparent
->mnt
;
1371 while (unlikely(d_mountpoint(nd
->path
.dentry
))) {
1372 struct mount
*mounted
;
1373 mounted
= __lookup_mnt(nd
->path
.mnt
, nd
->path
.dentry
);
1374 if (unlikely(read_seqretry(&mount_lock
, nd
->m_seq
)))
1378 nd
->path
.mnt
= &mounted
->mnt
;
1379 nd
->path
.dentry
= mounted
->mnt
.mnt_root
;
1380 inode
= nd
->path
.dentry
->d_inode
;
1381 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1388 * Follow down to the covering mount currently visible to userspace. At each
1389 * point, the filesystem owning that dentry may be queried as to whether the
1390 * caller is permitted to proceed or not.
1392 int follow_down(struct path
*path
)
1397 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1398 unlikely(managed
& DCACHE_MANAGED_DENTRY
)) {
1399 /* Allow the filesystem to manage the transit without i_mutex
1402 * We indicate to the filesystem if someone is trying to mount
1403 * something here. This gives autofs the chance to deny anyone
1404 * other than its daemon the right to mount on its
1407 * The filesystem may sleep at this point.
1409 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1410 BUG_ON(!path
->dentry
->d_op
);
1411 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1412 ret
= path
->dentry
->d_op
->d_manage(path
, false);
1414 return ret
== -EISDIR
? 0 : ret
;
1417 /* Transit to a mounted filesystem. */
1418 if (managed
& DCACHE_MOUNTED
) {
1419 struct vfsmount
*mounted
= lookup_mnt(path
);
1424 path
->mnt
= mounted
;
1425 path
->dentry
= dget(mounted
->mnt_root
);
1429 /* Don't handle automount points here */
1434 EXPORT_SYMBOL(follow_down
);
1437 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1439 static void follow_mount(struct path
*path
)
1441 while (d_mountpoint(path
->dentry
)) {
1442 struct vfsmount
*mounted
= lookup_mnt(path
);
1447 path
->mnt
= mounted
;
1448 path
->dentry
= dget(mounted
->mnt_root
);
1452 static int path_parent_directory(struct path
*path
)
1454 struct dentry
*old
= path
->dentry
;
1455 /* rare case of legitimate dget_parent()... */
1456 path
->dentry
= dget_parent(path
->dentry
);
1458 if (unlikely(!path_connected(path
)))
1463 static int follow_dotdot(struct nameidata
*nd
)
1466 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1467 nd
->path
.mnt
== nd
->root
.mnt
) {
1470 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1471 int ret
= path_parent_directory(&nd
->path
);
1476 if (!follow_up(&nd
->path
))
1479 follow_mount(&nd
->path
);
1480 nd
->inode
= nd
->path
.dentry
->d_inode
;
1485 * This looks up the name in dcache and possibly revalidates the found dentry.
1486 * NULL is returned if the dentry does not exist in the cache.
1488 static struct dentry
*lookup_dcache(const struct qstr
*name
,
1492 struct dentry
*dentry
= d_lookup(dir
, name
);
1494 int error
= d_revalidate(dentry
, flags
);
1495 if (unlikely(error
<= 0)) {
1497 d_invalidate(dentry
);
1499 return ERR_PTR(error
);
1506 * Call i_op->lookup on the dentry. The dentry must be negative and
1509 * dir->d_inode->i_mutex must be held
1511 static struct dentry
*lookup_real(struct inode
*dir
, struct dentry
*dentry
,
1516 /* Don't create child dentry for a dead directory. */
1517 if (unlikely(IS_DEADDIR(dir
))) {
1519 return ERR_PTR(-ENOENT
);
1522 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1523 if (unlikely(old
)) {
1530 static struct dentry
*__lookup_hash(const struct qstr
*name
,
1531 struct dentry
*base
, unsigned int flags
)
1533 struct dentry
*dentry
= lookup_dcache(name
, base
, flags
);
1538 dentry
= d_alloc(base
, name
);
1539 if (unlikely(!dentry
))
1540 return ERR_PTR(-ENOMEM
);
1542 return lookup_real(base
->d_inode
, dentry
, flags
);
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
;
1555 * Rename seqlock is not required here because in the off chance
1556 * of a false negative due to a concurrent rename, the caller is
1557 * going to fall back to non-racy lookup.
1559 if (nd
->flags
& LOOKUP_RCU
) {
1562 dentry
= __d_lookup_rcu(parent
, &nd
->last
, &seq
);
1563 if (unlikely(!dentry
)) {
1564 if (unlazy_walk(nd
))
1570 * This sequence count validates that the inode matches
1571 * the dentry name information from lookup.
1573 *inode
= d_backing_inode(dentry
);
1574 negative
= d_is_negative(dentry
);
1575 if (unlikely(read_seqcount_retry(&dentry
->d_seq
, seq
)))
1579 * This sequence count validates that the parent had no
1580 * changes while we did the lookup of the dentry above.
1582 * The memory barrier in read_seqcount_begin of child is
1583 * enough, we can use __read_seqcount_retry here.
1585 if (unlikely(__read_seqcount_retry(&parent
->d_seq
, nd
->seq
)))
1589 status
= d_revalidate(dentry
, nd
->flags
);
1590 if (likely(status
> 0)) {
1592 * Note: do negative dentry check after revalidation in
1593 * case that drops it.
1595 if (unlikely(negative
))
1598 path
->dentry
= dentry
;
1599 if (likely(__follow_mount_rcu(nd
, path
, inode
, seqp
)))
1602 if (unlazy_child(nd
, dentry
, seq
))
1604 if (unlikely(status
== -ECHILD
))
1605 /* we'd been told to redo it in non-rcu mode */
1606 status
= d_revalidate(dentry
, nd
->flags
);
1608 dentry
= __d_lookup(parent
, &nd
->last
);
1609 if (unlikely(!dentry
))
1611 status
= d_revalidate(dentry
, nd
->flags
);
1613 if (unlikely(status
<= 0)) {
1615 d_invalidate(dentry
);
1619 if (unlikely(d_is_negative(dentry
))) {
1625 path
->dentry
= dentry
;
1626 err
= follow_managed(path
, nd
);
1627 if (likely(err
> 0))
1628 *inode
= d_backing_inode(path
->dentry
);
1632 /* Fast lookup failed, do it the slow way */
1633 static struct dentry
*lookup_slow(const struct qstr
*name
,
1637 struct dentry
*dentry
= ERR_PTR(-ENOENT
), *old
;
1638 struct inode
*inode
= dir
->d_inode
;
1639 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq
);
1641 inode_lock_shared(inode
);
1642 /* Don't go there if it's already dead */
1643 if (unlikely(IS_DEADDIR(inode
)))
1646 dentry
= d_alloc_parallel(dir
, name
, &wq
);
1649 if (unlikely(!d_in_lookup(dentry
))) {
1650 if (!(flags
& LOOKUP_NO_REVAL
)) {
1651 int error
= d_revalidate(dentry
, flags
);
1652 if (unlikely(error
<= 0)) {
1654 d_invalidate(dentry
);
1659 dentry
= ERR_PTR(error
);
1663 old
= inode
->i_op
->lookup(inode
, dentry
, flags
);
1664 d_lookup_done(dentry
);
1665 if (unlikely(old
)) {
1671 inode_unlock_shared(inode
);
1675 static inline int may_lookup(struct nameidata
*nd
)
1677 if (nd
->flags
& LOOKUP_RCU
) {
1678 int err
= inode_permission(nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1681 if (unlazy_walk(nd
))
1684 return inode_permission(nd
->inode
, MAY_EXEC
);
1687 static inline int handle_dots(struct nameidata
*nd
, int type
)
1689 if (type
== LAST_DOTDOT
) {
1692 if (nd
->flags
& LOOKUP_RCU
) {
1693 return follow_dotdot_rcu(nd
);
1695 return follow_dotdot(nd
);
1700 static int pick_link(struct nameidata
*nd
, struct path
*link
,
1701 struct inode
*inode
, unsigned seq
)
1705 if (unlikely(nd
->total_link_count
++ >= MAXSYMLINKS
)) {
1706 path_to_nameidata(link
, nd
);
1709 if (!(nd
->flags
& LOOKUP_RCU
)) {
1710 if (link
->mnt
== nd
->path
.mnt
)
1713 error
= nd_alloc_stack(nd
);
1714 if (unlikely(error
)) {
1715 if (error
== -ECHILD
) {
1716 if (unlikely(!legitimize_path(nd
, link
, seq
))) {
1719 nd
->flags
&= ~LOOKUP_RCU
;
1720 nd
->path
.mnt
= NULL
;
1721 nd
->path
.dentry
= NULL
;
1722 if (!(nd
->flags
& LOOKUP_ROOT
))
1723 nd
->root
.mnt
= NULL
;
1725 } else if (likely(unlazy_walk(nd
)) == 0)
1726 error
= nd_alloc_stack(nd
);
1734 last
= nd
->stack
+ nd
->depth
++;
1736 clear_delayed_call(&last
->done
);
1737 nd
->link_inode
= inode
;
1742 enum {WALK_FOLLOW
= 1, WALK_MORE
= 2};
1745 * Do we need to follow links? We _really_ want to be able
1746 * to do this check without having to look at inode->i_op,
1747 * so we keep a cache of "no, this doesn't need follow_link"
1748 * for the common case.
1750 static inline int step_into(struct nameidata
*nd
, struct path
*path
,
1751 int flags
, struct inode
*inode
, unsigned seq
)
1753 if (!(flags
& WALK_MORE
) && nd
->depth
)
1755 if (likely(!d_is_symlink(path
->dentry
)) ||
1756 !(flags
& WALK_FOLLOW
|| nd
->flags
& LOOKUP_FOLLOW
)) {
1757 /* not a symlink or should not follow */
1758 path_to_nameidata(path
, nd
);
1763 /* make sure that d_is_symlink above matches inode */
1764 if (nd
->flags
& LOOKUP_RCU
) {
1765 if (read_seqcount_retry(&path
->dentry
->d_seq
, seq
))
1768 return pick_link(nd
, path
, inode
, seq
);
1771 static int walk_component(struct nameidata
*nd
, int flags
)
1774 struct inode
*inode
;
1778 * "." and ".." are special - ".." especially so because it has
1779 * to be able to know about the current root directory and
1780 * parent relationships.
1782 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
1783 err
= handle_dots(nd
, nd
->last_type
);
1784 if (!(flags
& WALK_MORE
) && nd
->depth
)
1788 err
= lookup_fast(nd
, &path
, &inode
, &seq
);
1789 if (unlikely(err
<= 0)) {
1792 path
.dentry
= lookup_slow(&nd
->last
, nd
->path
.dentry
,
1794 if (IS_ERR(path
.dentry
))
1795 return PTR_ERR(path
.dentry
);
1797 path
.mnt
= nd
->path
.mnt
;
1798 err
= follow_managed(&path
, nd
);
1799 if (unlikely(err
< 0))
1802 if (unlikely(d_is_negative(path
.dentry
))) {
1803 path_to_nameidata(&path
, nd
);
1807 seq
= 0; /* we are already out of RCU mode */
1808 inode
= d_backing_inode(path
.dentry
);
1811 return step_into(nd
, &path
, flags
, inode
, seq
);
1815 * We can do the critical dentry name comparison and hashing
1816 * operations one word at a time, but we are limited to:
1818 * - Architectures with fast unaligned word accesses. We could
1819 * do a "get_unaligned()" if this helps and is sufficiently
1822 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1823 * do not trap on the (extremely unlikely) case of a page
1824 * crossing operation.
1826 * - Furthermore, we need an efficient 64-bit compile for the
1827 * 64-bit case in order to generate the "number of bytes in
1828 * the final mask". Again, that could be replaced with a
1829 * efficient population count instruction or similar.
1831 #ifdef CONFIG_DCACHE_WORD_ACCESS
1833 #include <asm/word-at-a-time.h>
1837 /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */
1839 #elif defined(CONFIG_64BIT)
1841 * Register pressure in the mixing function is an issue, particularly
1842 * on 32-bit x86, but almost any function requires one state value and
1843 * one temporary. Instead, use a function designed for two state values
1844 * and no temporaries.
1846 * This function cannot create a collision in only two iterations, so
1847 * we have two iterations to achieve avalanche. In those two iterations,
1848 * we have six layers of mixing, which is enough to spread one bit's
1849 * influence out to 2^6 = 64 state bits.
1851 * Rotate constants are scored by considering either 64 one-bit input
1852 * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the
1853 * probability of that delta causing a change to each of the 128 output
1854 * bits, using a sample of random initial states.
1856 * The Shannon entropy of the computed probabilities is then summed
1857 * to produce a score. Ideally, any input change has a 50% chance of
1858 * toggling any given output bit.
1860 * Mixing scores (in bits) for (12,45):
1861 * Input delta: 1-bit 2-bit
1862 * 1 round: 713.3 42542.6
1863 * 2 rounds: 2753.7 140389.8
1864 * 3 rounds: 5954.1 233458.2
1865 * 4 rounds: 7862.6 256672.2
1866 * Perfect: 8192 258048
1867 * (64*128) (64*63/2 * 128)
1869 #define HASH_MIX(x, y, a) \
1871 y ^= x, x = rol64(x,12),\
1872 x += y, y = rol64(y,45),\
1876 * Fold two longs into one 32-bit hash value. This must be fast, but
1877 * latency isn't quite as critical, as there is a fair bit of additional
1878 * work done before the hash value is used.
1880 static inline unsigned int fold_hash(unsigned long x
, unsigned long y
)
1882 y
^= x
* GOLDEN_RATIO_64
;
1883 y
*= GOLDEN_RATIO_64
;
1887 #else /* 32-bit case */
1890 * Mixing scores (in bits) for (7,20):
1891 * Input delta: 1-bit 2-bit
1892 * 1 round: 330.3 9201.6
1893 * 2 rounds: 1246.4 25475.4
1894 * 3 rounds: 1907.1 31295.1
1895 * 4 rounds: 2042.3 31718.6
1896 * Perfect: 2048 31744
1897 * (32*64) (32*31/2 * 64)
1899 #define HASH_MIX(x, y, a) \
1901 y ^= x, x = rol32(x, 7),\
1902 x += y, y = rol32(y,20),\
1905 static inline unsigned int fold_hash(unsigned long x
, unsigned long y
)
1907 /* Use arch-optimized multiply if one exists */
1908 return __hash_32(y
^ __hash_32(x
));
1914 * Return the hash of a string of known length. This is carfully
1915 * designed to match hash_name(), which is the more critical function.
1916 * In particular, we must end by hashing a final word containing 0..7
1917 * payload bytes, to match the way that hash_name() iterates until it
1918 * finds the delimiter after the name.
1920 unsigned int full_name_hash(const void *salt
, const char *name
, unsigned int len
)
1922 unsigned long a
, x
= 0, y
= (unsigned long)salt
;
1927 a
= load_unaligned_zeropad(name
);
1928 if (len
< sizeof(unsigned long))
1931 name
+= sizeof(unsigned long);
1932 len
-= sizeof(unsigned long);
1934 x
^= a
& bytemask_from_count(len
);
1936 return fold_hash(x
, y
);
1938 EXPORT_SYMBOL(full_name_hash
);
1940 /* Return the "hash_len" (hash and length) of a null-terminated string */
1941 u64
hashlen_string(const void *salt
, const char *name
)
1943 unsigned long a
= 0, x
= 0, y
= (unsigned long)salt
;
1944 unsigned long adata
, mask
, len
;
1945 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
1952 len
+= sizeof(unsigned long);
1954 a
= load_unaligned_zeropad(name
+len
);
1955 } while (!has_zero(a
, &adata
, &constants
));
1957 adata
= prep_zero_mask(a
, adata
, &constants
);
1958 mask
= create_zero_mask(adata
);
1959 x
^= a
& zero_bytemask(mask
);
1961 return hashlen_create(fold_hash(x
, y
), len
+ find_zero(mask
));
1963 EXPORT_SYMBOL(hashlen_string
);
1966 * Calculate the length and hash of the path component, and
1967 * return the "hash_len" as the result.
1969 static inline u64
hash_name(const void *salt
, const char *name
)
1971 unsigned long a
= 0, b
, x
= 0, y
= (unsigned long)salt
;
1972 unsigned long adata
, bdata
, mask
, len
;
1973 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
1980 len
+= sizeof(unsigned long);
1982 a
= load_unaligned_zeropad(name
+len
);
1983 b
= a
^ REPEAT_BYTE('/');
1984 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
1986 adata
= prep_zero_mask(a
, adata
, &constants
);
1987 bdata
= prep_zero_mask(b
, bdata
, &constants
);
1988 mask
= create_zero_mask(adata
| bdata
);
1989 x
^= a
& zero_bytemask(mask
);
1991 return hashlen_create(fold_hash(x
, y
), len
+ find_zero(mask
));
1994 #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */
1996 /* Return the hash of a string of known length */
1997 unsigned int full_name_hash(const void *salt
, const char *name
, unsigned int len
)
1999 unsigned long hash
= init_name_hash(salt
);
2001 hash
= partial_name_hash((unsigned char)*name
++, hash
);
2002 return end_name_hash(hash
);
2004 EXPORT_SYMBOL(full_name_hash
);
2006 /* Return the "hash_len" (hash and length) of a null-terminated string */
2007 u64
hashlen_string(const void *salt
, const char *name
)
2009 unsigned long hash
= init_name_hash(salt
);
2010 unsigned long len
= 0, c
;
2012 c
= (unsigned char)*name
;
2015 hash
= partial_name_hash(c
, hash
);
2016 c
= (unsigned char)name
[len
];
2018 return hashlen_create(end_name_hash(hash
), len
);
2020 EXPORT_SYMBOL(hashlen_string
);
2023 * We know there's a real path component here of at least
2026 static inline u64
hash_name(const void *salt
, const char *name
)
2028 unsigned long hash
= init_name_hash(salt
);
2029 unsigned long len
= 0, c
;
2031 c
= (unsigned char)*name
;
2034 hash
= partial_name_hash(c
, hash
);
2035 c
= (unsigned char)name
[len
];
2036 } while (c
&& c
!= '/');
2037 return hashlen_create(end_name_hash(hash
), len
);
2044 * This is the basic name resolution function, turning a pathname into
2045 * the final dentry. We expect 'base' to be positive and a directory.
2047 * Returns 0 and nd will have valid dentry and mnt on success.
2048 * Returns error and drops reference to input namei data on failure.
2050 static int link_path_walk(const char *name
, struct nameidata
*nd
)
2059 /* At this point we know we have a real path component. */
2064 err
= may_lookup(nd
);
2068 hash_len
= hash_name(nd
->path
.dentry
, name
);
2071 if (name
[0] == '.') switch (hashlen_len(hash_len
)) {
2073 if (name
[1] == '.') {
2075 nd
->flags
|= LOOKUP_JUMPED
;
2081 if (likely(type
== LAST_NORM
)) {
2082 struct dentry
*parent
= nd
->path
.dentry
;
2083 nd
->flags
&= ~LOOKUP_JUMPED
;
2084 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
2085 struct qstr
this = { { .hash_len
= hash_len
}, .name
= name
};
2086 err
= parent
->d_op
->d_hash(parent
, &this);
2089 hash_len
= this.hash_len
;
2094 nd
->last
.hash_len
= hash_len
;
2095 nd
->last
.name
= name
;
2096 nd
->last_type
= type
;
2098 name
+= hashlen_len(hash_len
);
2102 * If it wasn't NUL, we know it was '/'. Skip that
2103 * slash, and continue until no more slashes.
2107 } while (unlikely(*name
== '/'));
2108 if (unlikely(!*name
)) {
2110 /* pathname body, done */
2113 name
= nd
->stack
[nd
->depth
- 1].name
;
2114 /* trailing symlink, done */
2117 /* last component of nested symlink */
2118 err
= walk_component(nd
, WALK_FOLLOW
);
2120 /* not the last component */
2121 err
= walk_component(nd
, WALK_FOLLOW
| WALK_MORE
);
2127 const char *s
= get_link(nd
);
2136 nd
->stack
[nd
->depth
- 1].name
= name
;
2141 if (unlikely(!d_can_lookup(nd
->path
.dentry
))) {
2142 if (nd
->flags
& LOOKUP_RCU
) {
2143 if (unlazy_walk(nd
))
2151 static const char *path_init(struct nameidata
*nd
, unsigned flags
)
2153 const char *s
= nd
->name
->name
;
2156 flags
&= ~LOOKUP_RCU
;
2158 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
2159 nd
->flags
= flags
| LOOKUP_JUMPED
| LOOKUP_PARENT
;
2161 if (flags
& LOOKUP_ROOT
) {
2162 struct dentry
*root
= nd
->root
.dentry
;
2163 struct inode
*inode
= root
->d_inode
;
2164 if (*s
&& unlikely(!d_can_lookup(root
)))
2165 return ERR_PTR(-ENOTDIR
);
2166 nd
->path
= nd
->root
;
2168 if (flags
& LOOKUP_RCU
) {
2170 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2171 nd
->root_seq
= nd
->seq
;
2172 nd
->m_seq
= read_seqbegin(&mount_lock
);
2174 path_get(&nd
->path
);
2179 nd
->root
.mnt
= NULL
;
2180 nd
->path
.mnt
= NULL
;
2181 nd
->path
.dentry
= NULL
;
2183 nd
->m_seq
= read_seqbegin(&mount_lock
);
2185 if (flags
& LOOKUP_RCU
)
2188 if (likely(!nd_jump_root(nd
)))
2190 nd
->root
.mnt
= NULL
;
2192 return ERR_PTR(-ECHILD
);
2193 } else if (nd
->dfd
== AT_FDCWD
) {
2194 if (flags
& LOOKUP_RCU
) {
2195 struct fs_struct
*fs
= current
->fs
;
2201 seq
= read_seqcount_begin(&fs
->seq
);
2203 nd
->inode
= nd
->path
.dentry
->d_inode
;
2204 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2205 } while (read_seqcount_retry(&fs
->seq
, seq
));
2207 get_fs_pwd(current
->fs
, &nd
->path
);
2208 nd
->inode
= nd
->path
.dentry
->d_inode
;
2212 /* Caller must check execute permissions on the starting path component */
2213 struct fd f
= fdget_raw(nd
->dfd
);
2214 struct dentry
*dentry
;
2217 return ERR_PTR(-EBADF
);
2219 dentry
= f
.file
->f_path
.dentry
;
2222 if (!d_can_lookup(dentry
)) {
2224 return ERR_PTR(-ENOTDIR
);
2228 nd
->path
= f
.file
->f_path
;
2229 if (flags
& LOOKUP_RCU
) {
2231 nd
->inode
= nd
->path
.dentry
->d_inode
;
2232 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2234 path_get(&nd
->path
);
2235 nd
->inode
= nd
->path
.dentry
->d_inode
;
2242 static const char *trailing_symlink(struct nameidata
*nd
)
2245 int error
= may_follow_link(nd
);
2246 if (unlikely(error
))
2247 return ERR_PTR(error
);
2248 nd
->flags
|= LOOKUP_PARENT
;
2249 nd
->stack
[0].name
= NULL
;
2254 static inline int lookup_last(struct nameidata
*nd
)
2256 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
2257 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2259 nd
->flags
&= ~LOOKUP_PARENT
;
2260 return walk_component(nd
, 0);
2263 static int handle_lookup_down(struct nameidata
*nd
)
2265 struct path path
= nd
->path
;
2266 struct inode
*inode
= nd
->inode
;
2267 unsigned seq
= nd
->seq
;
2270 if (nd
->flags
& LOOKUP_RCU
) {
2272 * don't bother with unlazy_walk on failure - we are
2273 * at the very beginning of walk, so we lose nothing
2274 * if we simply redo everything in non-RCU mode
2276 if (unlikely(!__follow_mount_rcu(nd
, &path
, &inode
, &seq
)))
2280 err
= follow_managed(&path
, nd
);
2281 if (unlikely(err
< 0))
2283 inode
= d_backing_inode(path
.dentry
);
2286 path_to_nameidata(&path
, nd
);
2292 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2293 static int path_lookupat(struct nameidata
*nd
, unsigned flags
, struct path
*path
)
2295 const char *s
= path_init(nd
, flags
);
2301 if (unlikely(flags
& LOOKUP_DOWN
)) {
2302 err
= handle_lookup_down(nd
);
2303 if (unlikely(err
< 0)) {
2309 while (!(err
= link_path_walk(s
, nd
))
2310 && ((err
= lookup_last(nd
)) > 0)) {
2311 s
= trailing_symlink(nd
);
2318 err
= complete_walk(nd
);
2320 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
)
2321 if (!d_can_lookup(nd
->path
.dentry
))
2325 nd
->path
.mnt
= NULL
;
2326 nd
->path
.dentry
= NULL
;
2332 static int filename_lookup(int dfd
, struct filename
*name
, unsigned flags
,
2333 struct path
*path
, struct path
*root
)
2336 struct nameidata nd
;
2338 return PTR_ERR(name
);
2339 if (unlikely(root
)) {
2341 flags
|= LOOKUP_ROOT
;
2343 set_nameidata(&nd
, dfd
, name
);
2344 retval
= path_lookupat(&nd
, flags
| LOOKUP_RCU
, path
);
2345 if (unlikely(retval
== -ECHILD
))
2346 retval
= path_lookupat(&nd
, flags
, path
);
2347 if (unlikely(retval
== -ESTALE
))
2348 retval
= path_lookupat(&nd
, flags
| LOOKUP_REVAL
, path
);
2350 if (likely(!retval
))
2351 audit_inode(name
, path
->dentry
, flags
& LOOKUP_PARENT
);
2352 restore_nameidata();
2357 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2358 static int path_parentat(struct nameidata
*nd
, unsigned flags
,
2359 struct path
*parent
)
2361 const char *s
= path_init(nd
, flags
);
2365 err
= link_path_walk(s
, nd
);
2367 err
= complete_walk(nd
);
2370 nd
->path
.mnt
= NULL
;
2371 nd
->path
.dentry
= NULL
;
2377 static struct filename
*filename_parentat(int dfd
, struct filename
*name
,
2378 unsigned int flags
, struct path
*parent
,
2379 struct qstr
*last
, int *type
)
2382 struct nameidata nd
;
2386 set_nameidata(&nd
, dfd
, name
);
2387 retval
= path_parentat(&nd
, flags
| LOOKUP_RCU
, parent
);
2388 if (unlikely(retval
== -ECHILD
))
2389 retval
= path_parentat(&nd
, flags
, parent
);
2390 if (unlikely(retval
== -ESTALE
))
2391 retval
= path_parentat(&nd
, flags
| LOOKUP_REVAL
, parent
);
2392 if (likely(!retval
)) {
2394 *type
= nd
.last_type
;
2395 audit_inode(name
, parent
->dentry
, LOOKUP_PARENT
);
2398 name
= ERR_PTR(retval
);
2400 restore_nameidata();
2404 /* does lookup, returns the object with parent locked */
2405 struct dentry
*kern_path_locked(const char *name
, struct path
*path
)
2407 struct filename
*filename
;
2412 filename
= filename_parentat(AT_FDCWD
, getname_kernel(name
), 0, path
,
2414 if (IS_ERR(filename
))
2415 return ERR_CAST(filename
);
2416 if (unlikely(type
!= LAST_NORM
)) {
2419 return ERR_PTR(-EINVAL
);
2421 inode_lock_nested(path
->dentry
->d_inode
, I_MUTEX_PARENT
);
2422 d
= __lookup_hash(&last
, path
->dentry
, 0);
2424 inode_unlock(path
->dentry
->d_inode
);
2431 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
2433 return filename_lookup(AT_FDCWD
, getname_kernel(name
),
2436 EXPORT_SYMBOL(kern_path
);
2439 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2440 * @dentry: pointer to dentry of the base directory
2441 * @mnt: pointer to vfs mount of the base directory
2442 * @name: pointer to file name
2443 * @flags: lookup flags
2444 * @path: pointer to struct path to fill
2446 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
2447 const char *name
, unsigned int flags
,
2450 struct path root
= {.mnt
= mnt
, .dentry
= dentry
};
2451 /* the first argument of filename_lookup() is ignored with root */
2452 return filename_lookup(AT_FDCWD
, getname_kernel(name
),
2453 flags
, path
, &root
);
2455 EXPORT_SYMBOL(vfs_path_lookup
);
2458 * lookup_one_len - filesystem helper to lookup single pathname component
2459 * @name: pathname component to lookup
2460 * @base: base directory to lookup from
2461 * @len: maximum length @len should be interpreted to
2463 * Note that this routine is purely a helper for filesystem usage and should
2464 * not be called by generic code.
2466 * The caller must hold base->i_mutex.
2468 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2474 WARN_ON_ONCE(!inode_is_locked(base
->d_inode
));
2478 this.hash
= full_name_hash(base
, name
, len
);
2480 return ERR_PTR(-EACCES
);
2482 if (unlikely(name
[0] == '.')) {
2483 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2484 return ERR_PTR(-EACCES
);
2488 c
= *(const unsigned char *)name
++;
2489 if (c
== '/' || c
== '\0')
2490 return ERR_PTR(-EACCES
);
2493 * See if the low-level filesystem might want
2494 * to use its own hash..
2496 if (base
->d_flags
& DCACHE_OP_HASH
) {
2497 int err
= base
->d_op
->d_hash(base
, &this);
2499 return ERR_PTR(err
);
2502 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
2504 return ERR_PTR(err
);
2506 return __lookup_hash(&this, base
, 0);
2508 EXPORT_SYMBOL(lookup_one_len
);
2511 * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
2512 * @name: pathname component to lookup
2513 * @base: base directory to lookup from
2514 * @len: maximum length @len should be interpreted to
2516 * Note that this routine is purely a helper for filesystem usage and should
2517 * not be called by generic code.
2519 * Unlike lookup_one_len, it should be called without the parent
2520 * i_mutex held, and will take the i_mutex itself if necessary.
2522 struct dentry
*lookup_one_len_unlocked(const char *name
,
2523 struct dentry
*base
, int len
)
2532 this.hash
= full_name_hash(base
, name
, len
);
2534 return ERR_PTR(-EACCES
);
2536 if (unlikely(name
[0] == '.')) {
2537 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2538 return ERR_PTR(-EACCES
);
2542 c
= *(const unsigned char *)name
++;
2543 if (c
== '/' || c
== '\0')
2544 return ERR_PTR(-EACCES
);
2547 * See if the low-level filesystem might want
2548 * to use its own hash..
2550 if (base
->d_flags
& DCACHE_OP_HASH
) {
2551 int err
= base
->d_op
->d_hash(base
, &this);
2553 return ERR_PTR(err
);
2556 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
2558 return ERR_PTR(err
);
2560 ret
= lookup_dcache(&this, base
, 0);
2562 ret
= lookup_slow(&this, base
, 0);
2565 EXPORT_SYMBOL(lookup_one_len_unlocked
);
2567 #ifdef CONFIG_UNIX98_PTYS
2568 int path_pts(struct path
*path
)
2570 /* Find something mounted on "pts" in the same directory as
2573 struct dentry
*child
, *parent
;
2577 ret
= path_parent_directory(path
);
2581 parent
= path
->dentry
;
2584 child
= d_hash_and_lookup(parent
, &this);
2588 path
->dentry
= child
;
2595 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
2596 struct path
*path
, int *empty
)
2598 return filename_lookup(dfd
, getname_flags(name
, flags
, empty
),
2601 EXPORT_SYMBOL(user_path_at_empty
);
2604 * mountpoint_last - look up last component for umount
2605 * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
2607 * This is a special lookup_last function just for umount. In this case, we
2608 * need to resolve the path without doing any revalidation.
2610 * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
2611 * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
2612 * in almost all cases, this lookup will be served out of the dcache. The only
2613 * cases where it won't are if nd->last refers to a symlink or the path is
2614 * bogus and it doesn't exist.
2617 * -error: if there was an error during lookup. This includes -ENOENT if the
2618 * lookup found a negative dentry.
2620 * 0: if we successfully resolved nd->last and found it to not to be a
2621 * symlink that needs to be followed.
2623 * 1: if we successfully resolved nd->last and found it to be a symlink
2624 * that needs to be followed.
2627 mountpoint_last(struct nameidata
*nd
)
2630 struct dentry
*dir
= nd
->path
.dentry
;
2633 /* If we're in rcuwalk, drop out of it to handle last component */
2634 if (nd
->flags
& LOOKUP_RCU
) {
2635 if (unlazy_walk(nd
))
2639 nd
->flags
&= ~LOOKUP_PARENT
;
2641 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
2642 error
= handle_dots(nd
, nd
->last_type
);
2645 path
.dentry
= dget(nd
->path
.dentry
);
2647 path
.dentry
= d_lookup(dir
, &nd
->last
);
2650 * No cached dentry. Mounted dentries are pinned in the
2651 * cache, so that means that this dentry is probably
2652 * a symlink or the path doesn't actually point
2653 * to a mounted dentry.
2655 path
.dentry
= lookup_slow(&nd
->last
, dir
,
2656 nd
->flags
| LOOKUP_NO_REVAL
);
2657 if (IS_ERR(path
.dentry
))
2658 return PTR_ERR(path
.dentry
);
2661 if (d_is_negative(path
.dentry
)) {
2665 path
.mnt
= nd
->path
.mnt
;
2666 return step_into(nd
, &path
, 0, d_backing_inode(path
.dentry
), 0);
2670 * path_mountpoint - look up a path to be umounted
2671 * @nd: lookup context
2672 * @flags: lookup flags
2673 * @path: pointer to container for result
2675 * Look up the given name, but don't attempt to revalidate the last component.
2676 * Returns 0 and "path" will be valid on success; Returns error otherwise.
2679 path_mountpoint(struct nameidata
*nd
, unsigned flags
, struct path
*path
)
2681 const char *s
= path_init(nd
, flags
);
2685 while (!(err
= link_path_walk(s
, nd
)) &&
2686 (err
= mountpoint_last(nd
)) > 0) {
2687 s
= trailing_symlink(nd
);
2695 nd
->path
.mnt
= NULL
;
2696 nd
->path
.dentry
= NULL
;
2704 filename_mountpoint(int dfd
, struct filename
*name
, struct path
*path
,
2707 struct nameidata nd
;
2710 return PTR_ERR(name
);
2711 set_nameidata(&nd
, dfd
, name
);
2712 error
= path_mountpoint(&nd
, flags
| LOOKUP_RCU
, path
);
2713 if (unlikely(error
== -ECHILD
))
2714 error
= path_mountpoint(&nd
, flags
, path
);
2715 if (unlikely(error
== -ESTALE
))
2716 error
= path_mountpoint(&nd
, flags
| LOOKUP_REVAL
, path
);
2718 audit_inode(name
, path
->dentry
, 0);
2719 restore_nameidata();
2725 * user_path_mountpoint_at - lookup a path from userland in order to umount it
2726 * @dfd: directory file descriptor
2727 * @name: pathname from userland
2728 * @flags: lookup flags
2729 * @path: pointer to container to hold result
2731 * A umount is a special case for path walking. We're not actually interested
2732 * in the inode in this situation, and ESTALE errors can be a problem. We
2733 * simply want track down the dentry and vfsmount attached at the mountpoint
2734 * and avoid revalidating the last component.
2736 * Returns 0 and populates "path" on success.
2739 user_path_mountpoint_at(int dfd
, const char __user
*name
, unsigned int flags
,
2742 return filename_mountpoint(dfd
, getname(name
), path
, flags
);
2746 kern_path_mountpoint(int dfd
, const char *name
, struct path
*path
,
2749 return filename_mountpoint(dfd
, getname_kernel(name
), path
, flags
);
2751 EXPORT_SYMBOL(kern_path_mountpoint
);
2753 int __check_sticky(struct inode
*dir
, struct inode
*inode
)
2755 kuid_t fsuid
= current_fsuid();
2757 if (uid_eq(inode
->i_uid
, fsuid
))
2759 if (uid_eq(dir
->i_uid
, fsuid
))
2761 return !capable_wrt_inode_uidgid(inode
, CAP_FOWNER
);
2763 EXPORT_SYMBOL(__check_sticky
);
2766 * Check whether we can remove a link victim from directory dir, check
2767 * whether the type of victim is right.
2768 * 1. We can't do it if dir is read-only (done in permission())
2769 * 2. We should have write and exec permissions on dir
2770 * 3. We can't remove anything from append-only dir
2771 * 4. We can't do anything with immutable dir (done in permission())
2772 * 5. If the sticky bit on dir is set we should either
2773 * a. be owner of dir, or
2774 * b. be owner of victim, or
2775 * c. have CAP_FOWNER capability
2776 * 6. If the victim is append-only or immutable we can't do antyhing with
2777 * links pointing to it.
2778 * 7. If the victim has an unknown uid or gid we can't change the inode.
2779 * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2780 * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2781 * 10. We can't remove a root or mountpoint.
2782 * 11. We don't allow removal of NFS sillyrenamed files; it's handled by
2783 * nfs_async_unlink().
2785 static int may_delete(struct inode
*dir
, struct dentry
*victim
, bool isdir
)
2787 struct inode
*inode
= d_backing_inode(victim
);
2790 if (d_is_negative(victim
))
2794 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
2795 audit_inode_child(dir
, victim
, AUDIT_TYPE_CHILD_DELETE
);
2797 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2803 if (check_sticky(dir
, inode
) || IS_APPEND(inode
) ||
2804 IS_IMMUTABLE(inode
) || IS_SWAPFILE(inode
) || HAS_UNMAPPED_ID(inode
))
2807 if (!d_is_dir(victim
))
2809 if (IS_ROOT(victim
))
2811 } else if (d_is_dir(victim
))
2813 if (IS_DEADDIR(dir
))
2815 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2820 /* Check whether we can create an object with dentry child in directory
2822 * 1. We can't do it if child already exists (open has special treatment for
2823 * this case, but since we are inlined it's OK)
2824 * 2. We can't do it if dir is read-only (done in permission())
2825 * 3. We can't do it if the fs can't represent the fsuid or fsgid.
2826 * 4. We should have write and exec permissions on dir
2827 * 5. We can't do it if dir is immutable (done in permission())
2829 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
2831 struct user_namespace
*s_user_ns
;
2832 audit_inode_child(dir
, child
, AUDIT_TYPE_CHILD_CREATE
);
2835 if (IS_DEADDIR(dir
))
2837 s_user_ns
= dir
->i_sb
->s_user_ns
;
2838 if (!kuid_has_mapping(s_user_ns
, current_fsuid()) ||
2839 !kgid_has_mapping(s_user_ns
, current_fsgid()))
2841 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2845 * p1 and p2 should be directories on the same fs.
2847 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2852 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
2856 mutex_lock(&p1
->d_sb
->s_vfs_rename_mutex
);
2858 p
= d_ancestor(p2
, p1
);
2860 inode_lock_nested(p2
->d_inode
, I_MUTEX_PARENT
);
2861 inode_lock_nested(p1
->d_inode
, I_MUTEX_CHILD
);
2865 p
= d_ancestor(p1
, p2
);
2867 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
2868 inode_lock_nested(p2
->d_inode
, I_MUTEX_CHILD
);
2872 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
2873 inode_lock_nested(p2
->d_inode
, I_MUTEX_PARENT2
);
2876 EXPORT_SYMBOL(lock_rename
);
2878 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
2880 inode_unlock(p1
->d_inode
);
2882 inode_unlock(p2
->d_inode
);
2883 mutex_unlock(&p1
->d_sb
->s_vfs_rename_mutex
);
2886 EXPORT_SYMBOL(unlock_rename
);
2888 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
2891 int error
= may_create(dir
, dentry
);
2895 if (!dir
->i_op
->create
)
2896 return -EACCES
; /* shouldn't it be ENOSYS? */
2899 error
= security_inode_create(dir
, dentry
, mode
);
2902 error
= dir
->i_op
->create(dir
, dentry
, mode
, want_excl
);
2904 fsnotify_create(dir
, dentry
);
2907 EXPORT_SYMBOL(vfs_create
);
2909 bool may_open_dev(const struct path
*path
)
2911 return !(path
->mnt
->mnt_flags
& MNT_NODEV
) &&
2912 !(path
->mnt
->mnt_sb
->s_iflags
& SB_I_NODEV
);
2915 static int may_open(const struct path
*path
, int acc_mode
, int flag
)
2917 struct dentry
*dentry
= path
->dentry
;
2918 struct inode
*inode
= dentry
->d_inode
;
2924 switch (inode
->i_mode
& S_IFMT
) {
2928 if (acc_mode
& MAY_WRITE
)
2933 if (!may_open_dev(path
))
2942 error
= inode_permission(inode
, MAY_OPEN
| acc_mode
);
2947 * An append-only file must be opened in append mode for writing.
2949 if (IS_APPEND(inode
)) {
2950 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
2956 /* O_NOATIME can only be set by the owner or superuser */
2957 if (flag
& O_NOATIME
&& !inode_owner_or_capable(inode
))
2963 static int handle_truncate(struct file
*filp
)
2965 const struct path
*path
= &filp
->f_path
;
2966 struct inode
*inode
= path
->dentry
->d_inode
;
2967 int error
= get_write_access(inode
);
2971 * Refuse to truncate files with mandatory locks held on them.
2973 error
= locks_verify_locked(filp
);
2975 error
= security_path_truncate(path
);
2977 error
= do_truncate(path
->dentry
, 0,
2978 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
2981 put_write_access(inode
);
2985 static inline int open_to_namei_flags(int flag
)
2987 if ((flag
& O_ACCMODE
) == 3)
2992 static int may_o_create(const struct path
*dir
, struct dentry
*dentry
, umode_t mode
)
2994 struct user_namespace
*s_user_ns
;
2995 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
2999 s_user_ns
= dir
->dentry
->d_sb
->s_user_ns
;
3000 if (!kuid_has_mapping(s_user_ns
, current_fsuid()) ||
3001 !kgid_has_mapping(s_user_ns
, current_fsgid()))
3004 error
= inode_permission(dir
->dentry
->d_inode
, MAY_WRITE
| MAY_EXEC
);
3008 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
3012 * Attempt to atomically look up, create and open a file from a negative
3015 * Returns 0 if successful. The file will have been created and attached to
3016 * @file by the filesystem calling finish_open().
3018 * Returns 1 if the file was looked up only or didn't need creating. The
3019 * caller will need to perform the open themselves. @path will have been
3020 * updated to point to the new dentry. This may be negative.
3022 * Returns an error code otherwise.
3024 static int atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
3025 struct path
*path
, struct file
*file
,
3026 const struct open_flags
*op
,
3027 int open_flag
, umode_t mode
,
3030 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
3031 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
3034 if (!(~open_flag
& (O_EXCL
| O_CREAT
))) /* both O_EXCL and O_CREAT */
3035 open_flag
&= ~O_TRUNC
;
3037 if (nd
->flags
& LOOKUP_DIRECTORY
)
3038 open_flag
|= O_DIRECTORY
;
3040 file
->f_path
.dentry
= DENTRY_NOT_SET
;
3041 file
->f_path
.mnt
= nd
->path
.mnt
;
3042 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
,
3043 open_to_namei_flags(open_flag
),
3045 d_lookup_done(dentry
);
3048 * We didn't have the inode before the open, so check open
3051 int acc_mode
= op
->acc_mode
;
3052 if (*opened
& FILE_CREATED
) {
3053 WARN_ON(!(open_flag
& O_CREAT
));
3054 fsnotify_create(dir
, dentry
);
3057 error
= may_open(&file
->f_path
, acc_mode
, open_flag
);
3058 if (WARN_ON(error
> 0))
3060 } else if (error
> 0) {
3061 if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
3064 if (file
->f_path
.dentry
) {
3066 dentry
= file
->f_path
.dentry
;
3068 if (*opened
& FILE_CREATED
)
3069 fsnotify_create(dir
, dentry
);
3070 if (unlikely(d_is_negative(dentry
))) {
3073 path
->dentry
= dentry
;
3074 path
->mnt
= nd
->path
.mnt
;
3084 * Look up and maybe create and open the last component.
3086 * Must be called with i_mutex held on parent.
3088 * Returns 0 if the file was successfully atomically created (if necessary) and
3089 * opened. In this case the file will be returned attached to @file.
3091 * Returns 1 if the file was not completely opened at this time, though lookups
3092 * and creations will have been performed and the dentry returned in @path will
3093 * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
3094 * specified then a negative dentry may be returned.
3096 * An error code is returned otherwise.
3098 * FILE_CREATE will be set in @*opened if the dentry was created and will be
3099 * cleared otherwise prior to returning.
3101 static int lookup_open(struct nameidata
*nd
, struct path
*path
,
3103 const struct open_flags
*op
,
3104 bool got_write
, int *opened
)
3106 struct dentry
*dir
= nd
->path
.dentry
;
3107 struct inode
*dir_inode
= dir
->d_inode
;
3108 int open_flag
= op
->open_flag
;
3109 struct dentry
*dentry
;
3110 int error
, create_error
= 0;
3111 umode_t mode
= op
->mode
;
3112 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq
);
3114 if (unlikely(IS_DEADDIR(dir_inode
)))
3117 *opened
&= ~FILE_CREATED
;
3118 dentry
= d_lookup(dir
, &nd
->last
);
3121 dentry
= d_alloc_parallel(dir
, &nd
->last
, &wq
);
3123 return PTR_ERR(dentry
);
3125 if (d_in_lookup(dentry
))
3128 error
= d_revalidate(dentry
, nd
->flags
);
3129 if (likely(error
> 0))
3133 d_invalidate(dentry
);
3137 if (dentry
->d_inode
) {
3138 /* Cached positive dentry: will open in f_op->open */
3143 * Checking write permission is tricky, bacuse we don't know if we are
3144 * going to actually need it: O_CREAT opens should work as long as the
3145 * file exists. But checking existence breaks atomicity. The trick is
3146 * to check access and if not granted clear O_CREAT from the flags.
3148 * Another problem is returing the "right" error value (e.g. for an
3149 * O_EXCL open we want to return EEXIST not EROFS).
3151 if (open_flag
& O_CREAT
) {
3152 if (!IS_POSIXACL(dir
->d_inode
))
3153 mode
&= ~current_umask();
3154 if (unlikely(!got_write
)) {
3155 create_error
= -EROFS
;
3156 open_flag
&= ~O_CREAT
;
3157 if (open_flag
& (O_EXCL
| O_TRUNC
))
3159 /* No side effects, safe to clear O_CREAT */
3161 create_error
= may_o_create(&nd
->path
, dentry
, mode
);
3163 open_flag
&= ~O_CREAT
;
3164 if (open_flag
& O_EXCL
)
3168 } else if ((open_flag
& (O_TRUNC
|O_WRONLY
|O_RDWR
)) &&
3169 unlikely(!got_write
)) {
3171 * No O_CREATE -> atomicity not a requirement -> fall
3172 * back to lookup + open
3177 if (dir_inode
->i_op
->atomic_open
) {
3178 error
= atomic_open(nd
, dentry
, path
, file
, op
, open_flag
,
3180 if (unlikely(error
== -ENOENT
) && create_error
)
3181 error
= create_error
;
3186 if (d_in_lookup(dentry
)) {
3187 struct dentry
*res
= dir_inode
->i_op
->lookup(dir_inode
, dentry
,
3189 d_lookup_done(dentry
);
3190 if (unlikely(res
)) {
3192 error
= PTR_ERR(res
);
3200 /* Negative dentry, just create the file */
3201 if (!dentry
->d_inode
&& (open_flag
& O_CREAT
)) {
3202 *opened
|= FILE_CREATED
;
3203 audit_inode_child(dir_inode
, dentry
, AUDIT_TYPE_CHILD_CREATE
);
3204 if (!dir_inode
->i_op
->create
) {
3208 error
= dir_inode
->i_op
->create(dir_inode
, dentry
, mode
,
3209 open_flag
& O_EXCL
);
3212 fsnotify_create(dir_inode
, dentry
);
3214 if (unlikely(create_error
) && !dentry
->d_inode
) {
3215 error
= create_error
;
3219 path
->dentry
= dentry
;
3220 path
->mnt
= nd
->path
.mnt
;
3229 * Handle the last step of open()
3231 static int do_last(struct nameidata
*nd
,
3232 struct file
*file
, const struct open_flags
*op
,
3235 struct dentry
*dir
= nd
->path
.dentry
;
3236 int open_flag
= op
->open_flag
;
3237 bool will_truncate
= (open_flag
& O_TRUNC
) != 0;
3238 bool got_write
= false;
3239 int acc_mode
= op
->acc_mode
;
3241 struct inode
*inode
;
3245 nd
->flags
&= ~LOOKUP_PARENT
;
3246 nd
->flags
|= op
->intent
;
3248 if (nd
->last_type
!= LAST_NORM
) {
3249 error
= handle_dots(nd
, nd
->last_type
);
3250 if (unlikely(error
))
3255 if (!(open_flag
& O_CREAT
)) {
3256 if (nd
->last
.name
[nd
->last
.len
])
3257 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
3258 /* we _can_ be in RCU mode here */
3259 error
= lookup_fast(nd
, &path
, &inode
, &seq
);
3260 if (likely(error
> 0))
3266 BUG_ON(nd
->inode
!= dir
->d_inode
);
3267 BUG_ON(nd
->flags
& LOOKUP_RCU
);
3269 /* create side of things */
3271 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
3272 * has been cleared when we got to the last component we are
3275 error
= complete_walk(nd
);
3279 audit_inode(nd
->name
, dir
, LOOKUP_PARENT
);
3280 /* trailing slashes? */
3281 if (unlikely(nd
->last
.name
[nd
->last
.len
]))
3285 if (open_flag
& (O_CREAT
| O_TRUNC
| O_WRONLY
| O_RDWR
)) {
3286 error
= mnt_want_write(nd
->path
.mnt
);
3290 * do _not_ fail yet - we might not need that or fail with
3291 * a different error; let lookup_open() decide; we'll be
3292 * dropping this one anyway.
3295 if (open_flag
& O_CREAT
)
3296 inode_lock(dir
->d_inode
);
3298 inode_lock_shared(dir
->d_inode
);
3299 error
= lookup_open(nd
, &path
, file
, op
, got_write
, opened
);
3300 if (open_flag
& O_CREAT
)
3301 inode_unlock(dir
->d_inode
);
3303 inode_unlock_shared(dir
->d_inode
);
3309 if ((*opened
& FILE_CREATED
) ||
3310 !S_ISREG(file_inode(file
)->i_mode
))
3311 will_truncate
= false;
3313 audit_inode(nd
->name
, file
->f_path
.dentry
, 0);
3317 if (*opened
& FILE_CREATED
) {
3318 /* Don't check for write permission, don't truncate */
3319 open_flag
&= ~O_TRUNC
;
3320 will_truncate
= false;
3322 path_to_nameidata(&path
, nd
);
3323 goto finish_open_created
;
3327 * If atomic_open() acquired write access it is dropped now due to
3328 * possible mount and symlink following (this might be optimized away if
3332 mnt_drop_write(nd
->path
.mnt
);
3336 error
= follow_managed(&path
, nd
);
3337 if (unlikely(error
< 0))
3340 if (unlikely(d_is_negative(path
.dentry
))) {
3341 path_to_nameidata(&path
, nd
);
3346 * create/update audit record if it already exists.
3348 audit_inode(nd
->name
, path
.dentry
, 0);
3350 if (unlikely((open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
))) {
3351 path_to_nameidata(&path
, nd
);
3355 seq
= 0; /* out of RCU mode, so the value doesn't matter */
3356 inode
= d_backing_inode(path
.dentry
);
3358 error
= step_into(nd
, &path
, 0, inode
, seq
);
3359 if (unlikely(error
))
3362 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
3363 error
= complete_walk(nd
);
3366 audit_inode(nd
->name
, nd
->path
.dentry
, 0);
3368 if ((open_flag
& O_CREAT
) && d_is_dir(nd
->path
.dentry
))
3371 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !d_can_lookup(nd
->path
.dentry
))
3373 if (!d_is_reg(nd
->path
.dentry
))
3374 will_truncate
= false;
3376 if (will_truncate
) {
3377 error
= mnt_want_write(nd
->path
.mnt
);
3382 finish_open_created
:
3383 error
= may_open(&nd
->path
, acc_mode
, open_flag
);
3386 BUG_ON(*opened
& FILE_OPENED
); /* once it's opened, it's opened */
3387 error
= vfs_open(&nd
->path
, file
, current_cred());
3390 *opened
|= FILE_OPENED
;
3392 error
= open_check_o_direct(file
);
3394 error
= ima_file_check(file
, op
->acc_mode
, *opened
);
3395 if (!error
&& will_truncate
)
3396 error
= handle_truncate(file
);
3398 if (unlikely(error
) && (*opened
& FILE_OPENED
))
3400 if (unlikely(error
> 0)) {
3405 mnt_drop_write(nd
->path
.mnt
);
3409 struct dentry
*vfs_tmpfile(struct dentry
*dentry
, umode_t mode
, int open_flag
)
3411 struct dentry
*child
= NULL
;
3412 struct inode
*dir
= dentry
->d_inode
;
3413 struct inode
*inode
;
3416 /* we want directory to be writable */
3417 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
3420 error
= -EOPNOTSUPP
;
3421 if (!dir
->i_op
->tmpfile
)
3424 child
= d_alloc(dentry
, &slash_name
);
3425 if (unlikely(!child
))
3427 error
= dir
->i_op
->tmpfile(dir
, child
, mode
);
3431 inode
= child
->d_inode
;
3432 if (unlikely(!inode
))
3434 if (!(open_flag
& O_EXCL
)) {
3435 spin_lock(&inode
->i_lock
);
3436 inode
->i_state
|= I_LINKABLE
;
3437 spin_unlock(&inode
->i_lock
);
3443 return ERR_PTR(error
);
3445 EXPORT_SYMBOL(vfs_tmpfile
);
3447 static int do_tmpfile(struct nameidata
*nd
, unsigned flags
,
3448 const struct open_flags
*op
,
3449 struct file
*file
, int *opened
)
3451 struct dentry
*child
;
3453 int error
= path_lookupat(nd
, flags
| LOOKUP_DIRECTORY
, &path
);
3454 if (unlikely(error
))
3456 error
= mnt_want_write(path
.mnt
);
3457 if (unlikely(error
))
3459 child
= vfs_tmpfile(path
.dentry
, op
->mode
, op
->open_flag
);
3460 error
= PTR_ERR(child
);
3461 if (unlikely(IS_ERR(child
)))
3464 path
.dentry
= child
;
3465 audit_inode(nd
->name
, child
, 0);
3466 /* Don't check for other permissions, the inode was just created */
3467 error
= may_open(&path
, 0, op
->open_flag
);
3470 file
->f_path
.mnt
= path
.mnt
;
3471 error
= finish_open(file
, child
, NULL
, opened
);
3474 error
= open_check_o_direct(file
);
3478 mnt_drop_write(path
.mnt
);
3484 static int do_o_path(struct nameidata
*nd
, unsigned flags
, struct file
*file
)
3487 int error
= path_lookupat(nd
, flags
, &path
);
3489 audit_inode(nd
->name
, path
.dentry
, 0);
3490 error
= vfs_open(&path
, file
, current_cred());
3496 static struct file
*path_openat(struct nameidata
*nd
,
3497 const struct open_flags
*op
, unsigned flags
)
3504 file
= get_empty_filp();
3508 file
->f_flags
= op
->open_flag
;
3510 if (unlikely(file
->f_flags
& __O_TMPFILE
)) {
3511 error
= do_tmpfile(nd
, flags
, op
, file
, &opened
);
3515 if (unlikely(file
->f_flags
& O_PATH
)) {
3516 error
= do_o_path(nd
, flags
, file
);
3518 opened
|= FILE_OPENED
;
3522 s
= path_init(nd
, flags
);
3527 while (!(error
= link_path_walk(s
, nd
)) &&
3528 (error
= do_last(nd
, file
, op
, &opened
)) > 0) {
3529 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
3530 s
= trailing_symlink(nd
);
3538 if (!(opened
& FILE_OPENED
)) {
3542 if (unlikely(error
)) {
3543 if (error
== -EOPENSTALE
) {
3544 if (flags
& LOOKUP_RCU
)
3549 file
= ERR_PTR(error
);
3554 struct file
*do_filp_open(int dfd
, struct filename
*pathname
,
3555 const struct open_flags
*op
)
3557 struct nameidata nd
;
3558 int flags
= op
->lookup_flags
;
3561 set_nameidata(&nd
, dfd
, pathname
);
3562 filp
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3563 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
3564 filp
= path_openat(&nd
, op
, flags
);
3565 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
3566 filp
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3567 restore_nameidata();
3571 struct file
*do_file_open_root(struct dentry
*dentry
, struct vfsmount
*mnt
,
3572 const char *name
, const struct open_flags
*op
)
3574 struct nameidata nd
;
3576 struct filename
*filename
;
3577 int flags
= op
->lookup_flags
| LOOKUP_ROOT
;
3580 nd
.root
.dentry
= dentry
;
3582 if (d_is_symlink(dentry
) && op
->intent
& LOOKUP_OPEN
)
3583 return ERR_PTR(-ELOOP
);
3585 filename
= getname_kernel(name
);
3586 if (IS_ERR(filename
))
3587 return ERR_CAST(filename
);
3589 set_nameidata(&nd
, -1, filename
);
3590 file
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3591 if (unlikely(file
== ERR_PTR(-ECHILD
)))
3592 file
= path_openat(&nd
, op
, flags
);
3593 if (unlikely(file
== ERR_PTR(-ESTALE
)))
3594 file
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3595 restore_nameidata();
3600 static struct dentry
*filename_create(int dfd
, struct filename
*name
,
3601 struct path
*path
, unsigned int lookup_flags
)
3603 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
3608 bool is_dir
= (lookup_flags
& LOOKUP_DIRECTORY
);
3611 * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
3612 * other flags passed in are ignored!
3614 lookup_flags
&= LOOKUP_REVAL
;
3616 name
= filename_parentat(dfd
, name
, lookup_flags
, path
, &last
, &type
);
3618 return ERR_CAST(name
);
3621 * Yucky last component or no last component at all?
3622 * (foo/., foo/.., /////)
3624 if (unlikely(type
!= LAST_NORM
))
3627 /* don't fail immediately if it's r/o, at least try to report other errors */
3628 err2
= mnt_want_write(path
->mnt
);
3630 * Do the final lookup.
3632 lookup_flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
3633 inode_lock_nested(path
->dentry
->d_inode
, I_MUTEX_PARENT
);
3634 dentry
= __lookup_hash(&last
, path
->dentry
, lookup_flags
);
3639 if (d_is_positive(dentry
))
3643 * Special case - lookup gave negative, but... we had foo/bar/
3644 * From the vfs_mknod() POV we just have a negative dentry -
3645 * all is fine. Let's be bastards - you had / on the end, you've
3646 * been asking for (non-existent) directory. -ENOENT for you.
3648 if (unlikely(!is_dir
&& last
.name
[last
.len
])) {
3652 if (unlikely(err2
)) {
3660 dentry
= ERR_PTR(error
);
3662 inode_unlock(path
->dentry
->d_inode
);
3664 mnt_drop_write(path
->mnt
);
3671 struct dentry
*kern_path_create(int dfd
, const char *pathname
,
3672 struct path
*path
, unsigned int lookup_flags
)
3674 return filename_create(dfd
, getname_kernel(pathname
),
3675 path
, lookup_flags
);
3677 EXPORT_SYMBOL(kern_path_create
);
3679 void done_path_create(struct path
*path
, struct dentry
*dentry
)
3682 inode_unlock(path
->dentry
->d_inode
);
3683 mnt_drop_write(path
->mnt
);
3686 EXPORT_SYMBOL(done_path_create
);
3688 inline struct dentry
*user_path_create(int dfd
, const char __user
*pathname
,
3689 struct path
*path
, unsigned int lookup_flags
)
3691 return filename_create(dfd
, getname(pathname
), path
, lookup_flags
);
3693 EXPORT_SYMBOL(user_path_create
);
3695 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3697 int error
= may_create(dir
, dentry
);
3702 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
3705 if (!dir
->i_op
->mknod
)
3708 error
= devcgroup_inode_mknod(mode
, dev
);
3712 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
3716 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
3718 fsnotify_create(dir
, dentry
);
3721 EXPORT_SYMBOL(vfs_mknod
);
3723 static int may_mknod(umode_t mode
)
3725 switch (mode
& S_IFMT
) {
3731 case 0: /* zero mode translates to S_IFREG */
3740 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
3743 struct dentry
*dentry
;
3746 unsigned int lookup_flags
= 0;
3748 error
= may_mknod(mode
);
3752 dentry
= user_path_create(dfd
, filename
, &path
, lookup_flags
);
3754 return PTR_ERR(dentry
);
3756 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3757 mode
&= ~current_umask();
3758 error
= security_path_mknod(&path
, dentry
, mode
, dev
);
3761 switch (mode
& S_IFMT
) {
3762 case 0: case S_IFREG
:
3763 error
= vfs_create(path
.dentry
->d_inode
,dentry
,mode
,true);
3765 ima_post_path_mknod(dentry
);
3767 case S_IFCHR
: case S_IFBLK
:
3768 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,
3769 new_decode_dev(dev
));
3771 case S_IFIFO
: case S_IFSOCK
:
3772 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,0);
3776 done_path_create(&path
, dentry
);
3777 if (retry_estale(error
, lookup_flags
)) {
3778 lookup_flags
|= LOOKUP_REVAL
;
3784 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
3786 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
3789 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
3791 int error
= may_create(dir
, dentry
);
3792 unsigned max_links
= dir
->i_sb
->s_max_links
;
3797 if (!dir
->i_op
->mkdir
)
3800 mode
&= (S_IRWXUGO
|S_ISVTX
);
3801 error
= security_inode_mkdir(dir
, dentry
, mode
);
3805 if (max_links
&& dir
->i_nlink
>= max_links
)
3808 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
3810 fsnotify_mkdir(dir
, dentry
);
3813 EXPORT_SYMBOL(vfs_mkdir
);
3815 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, umode_t
, mode
)
3817 struct dentry
*dentry
;
3820 unsigned int lookup_flags
= LOOKUP_DIRECTORY
;
3823 dentry
= user_path_create(dfd
, pathname
, &path
, lookup_flags
);
3825 return PTR_ERR(dentry
);
3827 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3828 mode
&= ~current_umask();
3829 error
= security_path_mkdir(&path
, dentry
, mode
);
3831 error
= vfs_mkdir(path
.dentry
->d_inode
, dentry
, mode
);
3832 done_path_create(&path
, dentry
);
3833 if (retry_estale(error
, lookup_flags
)) {
3834 lookup_flags
|= LOOKUP_REVAL
;
3840 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, umode_t
, mode
)
3842 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
3845 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
3847 int error
= may_delete(dir
, dentry
, 1);
3852 if (!dir
->i_op
->rmdir
)
3856 inode_lock(dentry
->d_inode
);
3859 if (is_local_mountpoint(dentry
))
3862 error
= security_inode_rmdir(dir
, dentry
);
3866 shrink_dcache_parent(dentry
);
3867 error
= dir
->i_op
->rmdir(dir
, dentry
);
3871 dentry
->d_inode
->i_flags
|= S_DEAD
;
3873 detach_mounts(dentry
);
3876 inode_unlock(dentry
->d_inode
);
3882 EXPORT_SYMBOL(vfs_rmdir
);
3884 static long do_rmdir(int dfd
, const char __user
*pathname
)
3887 struct filename
*name
;
3888 struct dentry
*dentry
;
3892 unsigned int lookup_flags
= 0;
3894 name
= filename_parentat(dfd
, getname(pathname
), lookup_flags
,
3895 &path
, &last
, &type
);
3897 return PTR_ERR(name
);
3911 error
= mnt_want_write(path
.mnt
);
3915 inode_lock_nested(path
.dentry
->d_inode
, I_MUTEX_PARENT
);
3916 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3917 error
= PTR_ERR(dentry
);
3920 if (!dentry
->d_inode
) {
3924 error
= security_path_rmdir(&path
, dentry
);
3927 error
= vfs_rmdir(path
.dentry
->d_inode
, dentry
);
3931 inode_unlock(path
.dentry
->d_inode
);
3932 mnt_drop_write(path
.mnt
);
3936 if (retry_estale(error
, lookup_flags
)) {
3937 lookup_flags
|= LOOKUP_REVAL
;
3943 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
3945 return do_rmdir(AT_FDCWD
, pathname
);
3949 * vfs_unlink - unlink a filesystem object
3950 * @dir: parent directory
3952 * @delegated_inode: returns victim inode, if the inode is delegated.
3954 * The caller must hold dir->i_mutex.
3956 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
3957 * return a reference to the inode in delegated_inode. The caller
3958 * should then break the delegation on that inode and retry. Because
3959 * breaking a delegation may take a long time, the caller should drop
3960 * dir->i_mutex before doing so.
3962 * Alternatively, a caller may pass NULL for delegated_inode. This may
3963 * be appropriate for callers that expect the underlying filesystem not
3964 * to be NFS exported.
3966 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
, struct inode
**delegated_inode
)
3968 struct inode
*target
= dentry
->d_inode
;
3969 int error
= may_delete(dir
, dentry
, 0);
3974 if (!dir
->i_op
->unlink
)
3978 if (is_local_mountpoint(dentry
))
3981 error
= security_inode_unlink(dir
, dentry
);
3983 error
= try_break_deleg(target
, delegated_inode
);
3986 error
= dir
->i_op
->unlink(dir
, dentry
);
3989 detach_mounts(dentry
);
3994 inode_unlock(target
);
3996 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
3997 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
3998 fsnotify_link_count(target
);
4004 EXPORT_SYMBOL(vfs_unlink
);
4007 * Make sure that the actual truncation of the file will occur outside its
4008 * directory's i_mutex. Truncate can take a long time if there is a lot of
4009 * writeout happening, and we don't want to prevent access to the directory
4010 * while waiting on the I/O.
4012 static long do_unlinkat(int dfd
, const char __user
*pathname
)
4015 struct filename
*name
;
4016 struct dentry
*dentry
;
4020 struct inode
*inode
= NULL
;
4021 struct inode
*delegated_inode
= NULL
;
4022 unsigned int lookup_flags
= 0;
4024 name
= filename_parentat(dfd
, getname(pathname
), lookup_flags
,
4025 &path
, &last
, &type
);
4027 return PTR_ERR(name
);
4030 if (type
!= LAST_NORM
)
4033 error
= mnt_want_write(path
.mnt
);
4037 inode_lock_nested(path
.dentry
->d_inode
, I_MUTEX_PARENT
);
4038 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
4039 error
= PTR_ERR(dentry
);
4040 if (!IS_ERR(dentry
)) {
4041 /* Why not before? Because we want correct error value */
4042 if (last
.name
[last
.len
])
4044 inode
= dentry
->d_inode
;
4045 if (d_is_negative(dentry
))
4048 error
= security_path_unlink(&path
, dentry
);
4051 error
= vfs_unlink(path
.dentry
->d_inode
, dentry
, &delegated_inode
);
4055 inode_unlock(path
.dentry
->d_inode
);
4057 iput(inode
); /* truncate the inode here */
4059 if (delegated_inode
) {
4060 error
= break_deleg_wait(&delegated_inode
);
4064 mnt_drop_write(path
.mnt
);
4068 if (retry_estale(error
, lookup_flags
)) {
4069 lookup_flags
|= LOOKUP_REVAL
;
4076 if (d_is_negative(dentry
))
4078 else if (d_is_dir(dentry
))
4085 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
4087 if ((flag
& ~AT_REMOVEDIR
) != 0)
4090 if (flag
& AT_REMOVEDIR
)
4091 return do_rmdir(dfd
, pathname
);
4093 return do_unlinkat(dfd
, pathname
);
4096 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
4098 return do_unlinkat(AT_FDCWD
, pathname
);
4101 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
4103 int error
= may_create(dir
, dentry
);
4108 if (!dir
->i_op
->symlink
)
4111 error
= security_inode_symlink(dir
, dentry
, oldname
);
4115 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
4117 fsnotify_create(dir
, dentry
);
4120 EXPORT_SYMBOL(vfs_symlink
);
4122 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
4123 int, newdfd
, const char __user
*, newname
)
4126 struct filename
*from
;
4127 struct dentry
*dentry
;
4129 unsigned int lookup_flags
= 0;
4131 from
= getname(oldname
);
4133 return PTR_ERR(from
);
4135 dentry
= user_path_create(newdfd
, newname
, &path
, lookup_flags
);
4136 error
= PTR_ERR(dentry
);
4140 error
= security_path_symlink(&path
, dentry
, from
->name
);
4142 error
= vfs_symlink(path
.dentry
->d_inode
, dentry
, from
->name
);
4143 done_path_create(&path
, dentry
);
4144 if (retry_estale(error
, lookup_flags
)) {
4145 lookup_flags
|= LOOKUP_REVAL
;
4153 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
4155 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
4159 * vfs_link - create a new link
4160 * @old_dentry: object to be linked
4162 * @new_dentry: where to create the new link
4163 * @delegated_inode: returns inode needing a delegation break
4165 * The caller must hold dir->i_mutex
4167 * If vfs_link discovers a delegation on the to-be-linked file in need
4168 * of breaking, it will return -EWOULDBLOCK and return a reference to the
4169 * inode in delegated_inode. The caller should then break the delegation
4170 * and retry. Because breaking a delegation may take a long time, the
4171 * caller should drop the i_mutex before doing so.
4173 * Alternatively, a caller may pass NULL for delegated_inode. This may
4174 * be appropriate for callers that expect the underlying filesystem not
4175 * to be NFS exported.
4177 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
, struct inode
**delegated_inode
)
4179 struct inode
*inode
= old_dentry
->d_inode
;
4180 unsigned max_links
= dir
->i_sb
->s_max_links
;
4186 error
= may_create(dir
, new_dentry
);
4190 if (dir
->i_sb
!= inode
->i_sb
)
4194 * A link to an append-only or immutable file cannot be created.
4196 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
4199 * Updating the link count will likely cause i_uid and i_gid to
4200 * be writen back improperly if their true value is unknown to
4203 if (HAS_UNMAPPED_ID(inode
))
4205 if (!dir
->i_op
->link
)
4207 if (S_ISDIR(inode
->i_mode
))
4210 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
4215 /* Make sure we don't allow creating hardlink to an unlinked file */
4216 if (inode
->i_nlink
== 0 && !(inode
->i_state
& I_LINKABLE
))
4218 else if (max_links
&& inode
->i_nlink
>= max_links
)
4221 error
= try_break_deleg(inode
, delegated_inode
);
4223 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
4226 if (!error
&& (inode
->i_state
& I_LINKABLE
)) {
4227 spin_lock(&inode
->i_lock
);
4228 inode
->i_state
&= ~I_LINKABLE
;
4229 spin_unlock(&inode
->i_lock
);
4231 inode_unlock(inode
);
4233 fsnotify_link(dir
, inode
, new_dentry
);
4236 EXPORT_SYMBOL(vfs_link
);
4239 * Hardlinks are often used in delicate situations. We avoid
4240 * security-related surprises by not following symlinks on the
4243 * We don't follow them on the oldname either to be compatible
4244 * with linux 2.0, and to avoid hard-linking to directories
4245 * and other special files. --ADM
4247 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
4248 int, newdfd
, const char __user
*, newname
, int, flags
)
4250 struct dentry
*new_dentry
;
4251 struct path old_path
, new_path
;
4252 struct inode
*delegated_inode
= NULL
;
4256 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0)
4259 * To use null names we require CAP_DAC_READ_SEARCH
4260 * This ensures that not everyone will be able to create
4261 * handlink using the passed filedescriptor.
4263 if (flags
& AT_EMPTY_PATH
) {
4264 if (!capable(CAP_DAC_READ_SEARCH
))
4269 if (flags
& AT_SYMLINK_FOLLOW
)
4270 how
|= LOOKUP_FOLLOW
;
4272 error
= user_path_at(olddfd
, oldname
, how
, &old_path
);
4276 new_dentry
= user_path_create(newdfd
, newname
, &new_path
,
4277 (how
& LOOKUP_REVAL
));
4278 error
= PTR_ERR(new_dentry
);
4279 if (IS_ERR(new_dentry
))
4283 if (old_path
.mnt
!= new_path
.mnt
)
4285 error
= may_linkat(&old_path
);
4286 if (unlikely(error
))
4288 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
4291 error
= vfs_link(old_path
.dentry
, new_path
.dentry
->d_inode
, new_dentry
, &delegated_inode
);
4293 done_path_create(&new_path
, new_dentry
);
4294 if (delegated_inode
) {
4295 error
= break_deleg_wait(&delegated_inode
);
4297 path_put(&old_path
);
4301 if (retry_estale(error
, how
)) {
4302 path_put(&old_path
);
4303 how
|= LOOKUP_REVAL
;
4307 path_put(&old_path
);
4312 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
4314 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4318 * vfs_rename - rename a filesystem object
4319 * @old_dir: parent of source
4320 * @old_dentry: source
4321 * @new_dir: parent of destination
4322 * @new_dentry: destination
4323 * @delegated_inode: returns an inode needing a delegation break
4324 * @flags: rename flags
4326 * The caller must hold multiple mutexes--see lock_rename()).
4328 * If vfs_rename discovers a delegation in need of breaking at either
4329 * the source or destination, it will return -EWOULDBLOCK and return a
4330 * reference to the inode in delegated_inode. The caller should then
4331 * break the delegation and retry. Because breaking a delegation may
4332 * take a long time, the caller should drop all locks before doing
4335 * Alternatively, a caller may pass NULL for delegated_inode. This may
4336 * be appropriate for callers that expect the underlying filesystem not
4337 * to be NFS exported.
4339 * The worst of all namespace operations - renaming directory. "Perverted"
4340 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4343 * a) we can get into loop creation.
4344 * b) race potential - two innocent renames can create a loop together.
4345 * That's where 4.4 screws up. Current fix: serialization on
4346 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
4348 * c) we have to lock _four_ objects - parents and victim (if it exists),
4349 * and source (if it is not a directory).
4350 * And that - after we got ->i_mutex on parents (until then we don't know
4351 * whether the target exists). Solution: try to be smart with locking
4352 * order for inodes. We rely on the fact that tree topology may change
4353 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
4354 * move will be locked. Thus we can rank directories by the tree
4355 * (ancestors first) and rank all non-directories after them.
4356 * That works since everybody except rename does "lock parent, lookup,
4357 * lock child" and rename is under ->s_vfs_rename_mutex.
4358 * HOWEVER, it relies on the assumption that any object with ->lookup()
4359 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4360 * we'd better make sure that there's no link(2) for them.
4361 * d) conversion from fhandle to dentry may come in the wrong moment - when
4362 * we are removing the target. Solution: we will have to grab ->i_mutex
4363 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
4364 * ->i_mutex on parents, which works but leads to some truly excessive
4367 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
4368 struct inode
*new_dir
, struct dentry
*new_dentry
,
4369 struct inode
**delegated_inode
, unsigned int flags
)
4372 bool is_dir
= d_is_dir(old_dentry
);
4373 struct inode
*source
= old_dentry
->d_inode
;
4374 struct inode
*target
= new_dentry
->d_inode
;
4375 bool new_is_dir
= false;
4376 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
4377 struct name_snapshot old_name
;
4379 if (source
== target
)
4382 error
= may_delete(old_dir
, old_dentry
, is_dir
);
4387 error
= may_create(new_dir
, new_dentry
);
4389 new_is_dir
= d_is_dir(new_dentry
);
4391 if (!(flags
& RENAME_EXCHANGE
))
4392 error
= may_delete(new_dir
, new_dentry
, is_dir
);
4394 error
= may_delete(new_dir
, new_dentry
, new_is_dir
);
4399 if (!old_dir
->i_op
->rename
)
4403 * If we are going to change the parent - check write permissions,
4404 * we'll need to flip '..'.
4406 if (new_dir
!= old_dir
) {
4408 error
= inode_permission(source
, MAY_WRITE
);
4412 if ((flags
& RENAME_EXCHANGE
) && new_is_dir
) {
4413 error
= inode_permission(target
, MAY_WRITE
);
4419 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
,
4424 take_dentry_name_snapshot(&old_name
, old_dentry
);
4426 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4427 lock_two_nondirectories(source
, target
);
4432 if (is_local_mountpoint(old_dentry
) || is_local_mountpoint(new_dentry
))
4435 if (max_links
&& new_dir
!= old_dir
) {
4437 if (is_dir
&& !new_is_dir
&& new_dir
->i_nlink
>= max_links
)
4439 if ((flags
& RENAME_EXCHANGE
) && !is_dir
&& new_is_dir
&&
4440 old_dir
->i_nlink
>= max_links
)
4443 if (is_dir
&& !(flags
& RENAME_EXCHANGE
) && target
)
4444 shrink_dcache_parent(new_dentry
);
4446 error
= try_break_deleg(source
, delegated_inode
);
4450 if (target
&& !new_is_dir
) {
4451 error
= try_break_deleg(target
, delegated_inode
);
4455 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
,
4456 new_dir
, new_dentry
, flags
);
4460 if (!(flags
& RENAME_EXCHANGE
) && target
) {
4462 target
->i_flags
|= S_DEAD
;
4463 dont_mount(new_dentry
);
4464 detach_mounts(new_dentry
);
4466 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
)) {
4467 if (!(flags
& RENAME_EXCHANGE
))
4468 d_move(old_dentry
, new_dentry
);
4470 d_exchange(old_dentry
, new_dentry
);
4473 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4474 unlock_two_nondirectories(source
, target
);
4476 inode_unlock(target
);
4479 fsnotify_move(old_dir
, new_dir
, old_name
.name
, is_dir
,
4480 !(flags
& RENAME_EXCHANGE
) ? target
: NULL
, old_dentry
);
4481 if (flags
& RENAME_EXCHANGE
) {
4482 fsnotify_move(new_dir
, old_dir
, old_dentry
->d_name
.name
,
4483 new_is_dir
, NULL
, new_dentry
);
4486 release_dentry_name_snapshot(&old_name
);
4490 EXPORT_SYMBOL(vfs_rename
);
4492 SYSCALL_DEFINE5(renameat2
, int, olddfd
, const char __user
*, oldname
,
4493 int, newdfd
, const char __user
*, newname
, unsigned int, flags
)
4495 struct dentry
*old_dentry
, *new_dentry
;
4496 struct dentry
*trap
;
4497 struct path old_path
, new_path
;
4498 struct qstr old_last
, new_last
;
4499 int old_type
, new_type
;
4500 struct inode
*delegated_inode
= NULL
;
4501 struct filename
*from
;
4502 struct filename
*to
;
4503 unsigned int lookup_flags
= 0, target_flags
= LOOKUP_RENAME_TARGET
;
4504 bool should_retry
= false;
4507 if (flags
& ~(RENAME_NOREPLACE
| RENAME_EXCHANGE
| RENAME_WHITEOUT
))
4510 if ((flags
& (RENAME_NOREPLACE
| RENAME_WHITEOUT
)) &&
4511 (flags
& RENAME_EXCHANGE
))
4514 if ((flags
& RENAME_WHITEOUT
) && !capable(CAP_MKNOD
))
4517 if (flags
& RENAME_EXCHANGE
)
4521 from
= filename_parentat(olddfd
, getname(oldname
), lookup_flags
,
4522 &old_path
, &old_last
, &old_type
);
4524 error
= PTR_ERR(from
);
4528 to
= filename_parentat(newdfd
, getname(newname
), lookup_flags
,
4529 &new_path
, &new_last
, &new_type
);
4531 error
= PTR_ERR(to
);
4536 if (old_path
.mnt
!= new_path
.mnt
)
4540 if (old_type
!= LAST_NORM
)
4543 if (flags
& RENAME_NOREPLACE
)
4545 if (new_type
!= LAST_NORM
)
4548 error
= mnt_want_write(old_path
.mnt
);
4553 trap
= lock_rename(new_path
.dentry
, old_path
.dentry
);
4555 old_dentry
= __lookup_hash(&old_last
, old_path
.dentry
, lookup_flags
);
4556 error
= PTR_ERR(old_dentry
);
4557 if (IS_ERR(old_dentry
))
4559 /* source must exist */
4561 if (d_is_negative(old_dentry
))
4563 new_dentry
= __lookup_hash(&new_last
, new_path
.dentry
, lookup_flags
| target_flags
);
4564 error
= PTR_ERR(new_dentry
);
4565 if (IS_ERR(new_dentry
))
4568 if ((flags
& RENAME_NOREPLACE
) && d_is_positive(new_dentry
))
4570 if (flags
& RENAME_EXCHANGE
) {
4572 if (d_is_negative(new_dentry
))
4575 if (!d_is_dir(new_dentry
)) {
4577 if (new_last
.name
[new_last
.len
])
4581 /* unless the source is a directory trailing slashes give -ENOTDIR */
4582 if (!d_is_dir(old_dentry
)) {
4584 if (old_last
.name
[old_last
.len
])
4586 if (!(flags
& RENAME_EXCHANGE
) && new_last
.name
[new_last
.len
])
4589 /* source should not be ancestor of target */
4591 if (old_dentry
== trap
)
4593 /* target should not be an ancestor of source */
4594 if (!(flags
& RENAME_EXCHANGE
))
4596 if (new_dentry
== trap
)
4599 error
= security_path_rename(&old_path
, old_dentry
,
4600 &new_path
, new_dentry
, flags
);
4603 error
= vfs_rename(old_path
.dentry
->d_inode
, old_dentry
,
4604 new_path
.dentry
->d_inode
, new_dentry
,
4605 &delegated_inode
, flags
);
4611 unlock_rename(new_path
.dentry
, old_path
.dentry
);
4612 if (delegated_inode
) {
4613 error
= break_deleg_wait(&delegated_inode
);
4617 mnt_drop_write(old_path
.mnt
);
4619 if (retry_estale(error
, lookup_flags
))
4620 should_retry
= true;
4621 path_put(&new_path
);
4624 path_put(&old_path
);
4627 should_retry
= false;
4628 lookup_flags
|= LOOKUP_REVAL
;
4635 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
4636 int, newdfd
, const char __user
*, newname
)
4638 return sys_renameat2(olddfd
, oldname
, newdfd
, newname
, 0);
4641 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
4643 return sys_renameat2(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4646 int vfs_whiteout(struct inode
*dir
, struct dentry
*dentry
)
4648 int error
= may_create(dir
, dentry
);
4652 if (!dir
->i_op
->mknod
)
4655 return dir
->i_op
->mknod(dir
, dentry
,
4656 S_IFCHR
| WHITEOUT_MODE
, WHITEOUT_DEV
);
4658 EXPORT_SYMBOL(vfs_whiteout
);
4660 int readlink_copy(char __user
*buffer
, int buflen
, const char *link
)
4662 int len
= PTR_ERR(link
);
4667 if (len
> (unsigned) buflen
)
4669 if (copy_to_user(buffer
, link
, len
))
4676 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
4677 * have ->get_link() not calling nd_jump_link(). Using (or not using) it
4678 * for any given inode is up to filesystem.
4680 static int generic_readlink(struct dentry
*dentry
, char __user
*buffer
,
4683 DEFINE_DELAYED_CALL(done
);
4684 struct inode
*inode
= d_inode(dentry
);
4685 const char *link
= inode
->i_link
;
4689 link
= inode
->i_op
->get_link(dentry
, inode
, &done
);
4691 return PTR_ERR(link
);
4693 res
= readlink_copy(buffer
, buflen
, link
);
4694 do_delayed_call(&done
);
4699 * vfs_readlink - copy symlink body into userspace buffer
4700 * @dentry: dentry on which to get symbolic link
4701 * @buffer: user memory pointer
4702 * @buflen: size of buffer
4704 * Does not touch atime. That's up to the caller if necessary
4706 * Does not call security hook.
4708 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4710 struct inode
*inode
= d_inode(dentry
);
4712 if (unlikely(!(inode
->i_opflags
& IOP_DEFAULT_READLINK
))) {
4713 if (unlikely(inode
->i_op
->readlink
))
4714 return inode
->i_op
->readlink(dentry
, buffer
, buflen
);
4716 if (!d_is_symlink(dentry
))
4719 spin_lock(&inode
->i_lock
);
4720 inode
->i_opflags
|= IOP_DEFAULT_READLINK
;
4721 spin_unlock(&inode
->i_lock
);
4724 return generic_readlink(dentry
, buffer
, buflen
);
4726 EXPORT_SYMBOL(vfs_readlink
);
4729 * vfs_get_link - get symlink body
4730 * @dentry: dentry on which to get symbolic link
4731 * @done: caller needs to free returned data with this
4733 * Calls security hook and i_op->get_link() on the supplied inode.
4735 * It does not touch atime. That's up to the caller if necessary.
4737 * Does not work on "special" symlinks like /proc/$$/fd/N
4739 const char *vfs_get_link(struct dentry
*dentry
, struct delayed_call
*done
)
4741 const char *res
= ERR_PTR(-EINVAL
);
4742 struct inode
*inode
= d_inode(dentry
);
4744 if (d_is_symlink(dentry
)) {
4745 res
= ERR_PTR(security_inode_readlink(dentry
));
4747 res
= inode
->i_op
->get_link(dentry
, inode
, done
);
4751 EXPORT_SYMBOL(vfs_get_link
);
4753 /* get the link contents into pagecache */
4754 const char *page_get_link(struct dentry
*dentry
, struct inode
*inode
,
4755 struct delayed_call
*callback
)
4759 struct address_space
*mapping
= inode
->i_mapping
;
4762 page
= find_get_page(mapping
, 0);
4764 return ERR_PTR(-ECHILD
);
4765 if (!PageUptodate(page
)) {
4767 return ERR_PTR(-ECHILD
);
4770 page
= read_mapping_page(mapping
, 0, NULL
);
4774 set_delayed_call(callback
, page_put_link
, page
);
4775 BUG_ON(mapping_gfp_mask(mapping
) & __GFP_HIGHMEM
);
4776 kaddr
= page_address(page
);
4777 nd_terminate_link(kaddr
, inode
->i_size
, PAGE_SIZE
- 1);
4781 EXPORT_SYMBOL(page_get_link
);
4783 void page_put_link(void *arg
)
4787 EXPORT_SYMBOL(page_put_link
);
4789 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4791 DEFINE_DELAYED_CALL(done
);
4792 int res
= readlink_copy(buffer
, buflen
,
4793 page_get_link(dentry
, d_inode(dentry
),
4795 do_delayed_call(&done
);
4798 EXPORT_SYMBOL(page_readlink
);
4801 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
4803 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
4805 struct address_space
*mapping
= inode
->i_mapping
;
4809 unsigned int flags
= 0;
4811 flags
|= AOP_FLAG_NOFS
;
4814 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
4815 flags
, &page
, &fsdata
);
4819 memcpy(page_address(page
), symname
, len
-1);
4821 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
4828 mark_inode_dirty(inode
);
4833 EXPORT_SYMBOL(__page_symlink
);
4835 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
4837 return __page_symlink(inode
, symname
, len
,
4838 !mapping_gfp_constraint(inode
->i_mapping
, __GFP_FS
));
4840 EXPORT_SYMBOL(page_symlink
);
4842 const struct inode_operations page_symlink_inode_operations
= {
4843 .get_link
= page_get_link
,
4845 EXPORT_SYMBOL(page_symlink_inode_operations
);