4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * Some corrections by tytso.
11 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
14 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
17 #include <linux/init.h>
18 #include <linux/export.h>
19 #include <linux/kernel.h>
20 #include <linux/slab.h>
22 #include <linux/namei.h>
23 #include <linux/pagemap.h>
24 #include <linux/fsnotify.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/ima.h>
28 #include <linux/syscalls.h>
29 #include <linux/mount.h>
30 #include <linux/audit.h>
31 #include <linux/capability.h>
32 #include <linux/file.h>
33 #include <linux/fcntl.h>
34 #include <linux/device_cgroup.h>
35 #include <linux/fs_struct.h>
36 #include <linux/posix_acl.h>
37 #include <linux/hash.h>
38 #include <asm/uaccess.h>
43 /* [Feb-1997 T. Schoebel-Theuer]
44 * Fundamental changes in the pathname lookup mechanisms (namei)
45 * were necessary because of omirr. The reason is that omirr needs
46 * to know the _real_ pathname, not the user-supplied one, in case
47 * of symlinks (and also when transname replacements occur).
49 * The new code replaces the old recursive symlink resolution with
50 * an iterative one (in case of non-nested symlink chains). It does
51 * this with calls to <fs>_follow_link().
52 * As a side effect, dir_namei(), _namei() and follow_link() are now
53 * replaced with a single function lookup_dentry() that can handle all
54 * the special cases of the former code.
56 * With the new dcache, the pathname is stored at each inode, at least as
57 * long as the refcount of the inode is positive. As a side effect, the
58 * size of the dcache depends on the inode cache and thus is dynamic.
60 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
61 * resolution to correspond with current state of the code.
63 * Note that the symlink resolution is not *completely* iterative.
64 * There is still a significant amount of tail- and mid- recursion in
65 * the algorithm. Also, note that <fs>_readlink() is not used in
66 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
67 * may return different results than <fs>_follow_link(). Many virtual
68 * filesystems (including /proc) exhibit this behavior.
71 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
72 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
73 * and the name already exists in form of a symlink, try to create the new
74 * name indicated by the symlink. The old code always complained that the
75 * name already exists, due to not following the symlink even if its target
76 * is nonexistent. The new semantics affects also mknod() and link() when
77 * the name is a symlink pointing to a non-existent name.
79 * I don't know which semantics is the right one, since I have no access
80 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
81 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
82 * "old" one. Personally, I think the new semantics is much more logical.
83 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
84 * file does succeed in both HP-UX and SunOs, but not in Solaris
85 * and in the old Linux semantics.
88 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
89 * semantics. See the comments in "open_namei" and "do_link" below.
91 * [10-Sep-98 Alan Modra] Another symlink change.
94 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
95 * inside the path - always follow.
96 * in the last component in creation/removal/renaming - never follow.
97 * if LOOKUP_FOLLOW passed - follow.
98 * if the pathname has trailing slashes - follow.
99 * otherwise - don't follow.
100 * (applied in that order).
102 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
103 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
104 * During the 2.4 we need to fix the userland stuff depending on it -
105 * hopefully we will be able to get rid of that wart in 2.5. So far only
106 * XEmacs seems to be relying on it...
109 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
110 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
111 * any extra contention...
114 /* In order to reduce some races, while at the same time doing additional
115 * checking and hopefully speeding things up, we copy filenames to the
116 * kernel data space before using them..
118 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
119 * PATH_MAX includes the nul terminator --RR.
122 #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname))
125 getname_flags(const char __user
*filename
, int flags
, int *empty
)
127 struct filename
*result
;
131 result
= audit_reusename(filename
);
135 result
= __getname();
136 if (unlikely(!result
))
137 return ERR_PTR(-ENOMEM
);
140 * First, try to embed the struct filename inside the names_cache
143 kname
= (char *)result
->iname
;
144 result
->name
= kname
;
146 len
= strncpy_from_user(kname
, filename
, EMBEDDED_NAME_MAX
);
147 if (unlikely(len
< 0)) {
153 * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
154 * separate struct filename so we can dedicate the entire
155 * names_cache allocation for the pathname, and re-do the copy from
158 if (unlikely(len
== EMBEDDED_NAME_MAX
)) {
159 const size_t size
= offsetof(struct filename
, iname
[1]);
160 kname
= (char *)result
;
163 * size is chosen that way we to guarantee that
164 * result->iname[0] is within the same object and that
165 * kname can't be equal to result->iname, no matter what.
167 result
= kzalloc(size
, GFP_KERNEL
);
168 if (unlikely(!result
)) {
170 return ERR_PTR(-ENOMEM
);
172 result
->name
= kname
;
173 len
= strncpy_from_user(kname
, filename
, PATH_MAX
);
174 if (unlikely(len
< 0)) {
179 if (unlikely(len
== PATH_MAX
)) {
182 return ERR_PTR(-ENAMETOOLONG
);
187 /* The empty path is special. */
188 if (unlikely(!len
)) {
191 if (!(flags
& LOOKUP_EMPTY
)) {
193 return ERR_PTR(-ENOENT
);
197 result
->uptr
= filename
;
198 result
->aname
= NULL
;
199 audit_getname(result
);
204 getname(const char __user
* filename
)
206 return getname_flags(filename
, 0, NULL
);
210 getname_kernel(const char * filename
)
212 struct filename
*result
;
213 int len
= strlen(filename
) + 1;
215 result
= __getname();
216 if (unlikely(!result
))
217 return ERR_PTR(-ENOMEM
);
219 if (len
<= EMBEDDED_NAME_MAX
) {
220 result
->name
= (char *)result
->iname
;
221 } else if (len
<= PATH_MAX
) {
222 struct filename
*tmp
;
224 tmp
= kmalloc(sizeof(*tmp
), GFP_KERNEL
);
225 if (unlikely(!tmp
)) {
227 return ERR_PTR(-ENOMEM
);
229 tmp
->name
= (char *)result
;
233 return ERR_PTR(-ENAMETOOLONG
);
235 memcpy((char *)result
->name
, filename
, len
);
237 result
->aname
= NULL
;
239 audit_getname(result
);
244 void putname(struct filename
*name
)
246 BUG_ON(name
->refcnt
<= 0);
248 if (--name
->refcnt
> 0)
251 if (name
->name
!= name
->iname
) {
252 __putname(name
->name
);
258 static int check_acl(struct inode
*inode
, int mask
)
260 #ifdef CONFIG_FS_POSIX_ACL
261 struct posix_acl
*acl
;
263 if (mask
& MAY_NOT_BLOCK
) {
264 acl
= get_cached_acl_rcu(inode
, ACL_TYPE_ACCESS
);
267 /* no ->get_acl() calls in RCU mode... */
268 if (acl
== ACL_NOT_CACHED
)
270 return posix_acl_permission(inode
, acl
, mask
& ~MAY_NOT_BLOCK
);
273 acl
= get_acl(inode
, ACL_TYPE_ACCESS
);
277 int error
= posix_acl_permission(inode
, acl
, mask
);
278 posix_acl_release(acl
);
287 * This does the basic permission checking
289 static int acl_permission_check(struct inode
*inode
, int mask
)
291 unsigned int mode
= inode
->i_mode
;
293 if (likely(uid_eq(current_fsuid(), inode
->i_uid
)))
296 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
)) {
297 int error
= check_acl(inode
, mask
);
298 if (error
!= -EAGAIN
)
302 if (in_group_p(inode
->i_gid
))
307 * If the DACs are ok we don't need any capability check.
309 if ((mask
& ~mode
& (MAY_READ
| MAY_WRITE
| MAY_EXEC
)) == 0)
315 * generic_permission - check for access rights on a Posix-like filesystem
316 * @inode: inode to check access rights for
317 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
319 * Used to check for read/write/execute permissions on a file.
320 * We use "fsuid" for this, letting us set arbitrary permissions
321 * for filesystem access without changing the "normal" uids which
322 * are used for other things.
324 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
325 * request cannot be satisfied (eg. requires blocking or too much complexity).
326 * It would then be called again in ref-walk mode.
328 int generic_permission(struct inode
*inode
, int mask
)
333 * Do the basic permission checks.
335 ret
= acl_permission_check(inode
, mask
);
339 if (S_ISDIR(inode
->i_mode
)) {
340 /* DACs are overridable for directories */
341 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_OVERRIDE
))
343 if (!(mask
& MAY_WRITE
))
344 if (capable_wrt_inode_uidgid(inode
,
345 CAP_DAC_READ_SEARCH
))
350 * Read/write DACs are always overridable.
351 * Executable DACs are overridable when there is
352 * at least one exec bit set.
354 if (!(mask
& MAY_EXEC
) || (inode
->i_mode
& S_IXUGO
))
355 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_OVERRIDE
))
359 * Searching includes executable on directories, else just read.
361 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
362 if (mask
== MAY_READ
)
363 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_READ_SEARCH
))
368 EXPORT_SYMBOL(generic_permission
);
371 * We _really_ want to just do "generic_permission()" without
372 * even looking at the inode->i_op values. So we keep a cache
373 * flag in inode->i_opflags, that says "this has not special
374 * permission function, use the fast case".
376 static inline int do_inode_permission(struct inode
*inode
, int mask
)
378 if (unlikely(!(inode
->i_opflags
& IOP_FASTPERM
))) {
379 if (likely(inode
->i_op
->permission
))
380 return inode
->i_op
->permission(inode
, mask
);
382 /* This gets set once for the inode lifetime */
383 spin_lock(&inode
->i_lock
);
384 inode
->i_opflags
|= IOP_FASTPERM
;
385 spin_unlock(&inode
->i_lock
);
387 return generic_permission(inode
, mask
);
391 * __inode_permission - Check for access rights to a given inode
392 * @inode: Inode to check permission on
393 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
395 * Check for read/write/execute permissions on an inode.
397 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
399 * This does not check for a read-only file system. You probably want
400 * inode_permission().
402 int __inode_permission(struct inode
*inode
, int mask
)
406 if (unlikely(mask
& MAY_WRITE
)) {
408 * Nobody gets write access to an immutable file.
410 if (IS_IMMUTABLE(inode
))
414 retval
= do_inode_permission(inode
, mask
);
418 retval
= devcgroup_inode_permission(inode
, mask
);
422 return security_inode_permission(inode
, mask
);
424 EXPORT_SYMBOL(__inode_permission
);
427 * sb_permission - Check superblock-level permissions
428 * @sb: Superblock of inode to check permission on
429 * @inode: Inode to check permission on
430 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
432 * Separate out file-system wide checks from inode-specific permission checks.
434 static int sb_permission(struct super_block
*sb
, struct inode
*inode
, int mask
)
436 if (unlikely(mask
& MAY_WRITE
)) {
437 umode_t mode
= inode
->i_mode
;
439 /* Nobody gets write access to a read-only fs. */
440 if ((sb
->s_flags
& MS_RDONLY
) &&
441 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
448 * inode_permission - Check for access rights to a given inode
449 * @inode: Inode to check permission on
450 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
452 * Check for read/write/execute permissions on an inode. We use fs[ug]id for
453 * this, letting us set arbitrary permissions for filesystem access without
454 * changing the "normal" UIDs which are used for other things.
456 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
458 int inode_permission(struct inode
*inode
, int mask
)
462 retval
= sb_permission(inode
->i_sb
, inode
, mask
);
465 return __inode_permission(inode
, mask
);
467 EXPORT_SYMBOL(inode_permission
);
470 * path_get - get a reference to a path
471 * @path: path to get the reference to
473 * Given a path increment the reference count to the dentry and the vfsmount.
475 void path_get(const struct path
*path
)
480 EXPORT_SYMBOL(path_get
);
483 * path_put - put a reference to a path
484 * @path: path to put the reference to
486 * Given a path decrement the reference count to the dentry and the vfsmount.
488 void path_put(const struct path
*path
)
493 EXPORT_SYMBOL(path_put
);
495 #define EMBEDDED_LEVELS 2
500 struct inode
*inode
; /* path.dentry.d_inode */
502 unsigned seq
, m_seq
, root_seq
;
505 int total_link_count
;
512 } *stack
, internal
[EMBEDDED_LEVELS
];
515 static struct nameidata
*set_nameidata(struct nameidata
*p
)
517 struct nameidata
*old
= current
->nameidata
;
518 p
->stack
= p
->internal
;
519 p
->total_link_count
= old
? old
->total_link_count
: 0;
520 current
->nameidata
= p
;
524 static void restore_nameidata(struct nameidata
*old
)
526 struct nameidata
*now
= current
->nameidata
;
528 current
->nameidata
= old
;
530 old
->total_link_count
= now
->total_link_count
;
531 if (now
->stack
!= now
->internal
) {
533 now
->stack
= now
->internal
;
537 static int __nd_alloc_stack(struct nameidata
*nd
)
541 if (nd
->flags
& LOOKUP_RCU
) {
542 p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
547 p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
552 memcpy(p
, nd
->internal
, sizeof(nd
->internal
));
557 static inline int nd_alloc_stack(struct nameidata
*nd
)
559 if (likely(nd
->depth
!= EMBEDDED_LEVELS
))
561 if (likely(nd
->stack
!= nd
->internal
))
563 return __nd_alloc_stack(nd
);
566 static void drop_links(struct nameidata
*nd
)
570 struct saved
*last
= nd
->stack
+ i
;
571 struct inode
*inode
= last
->inode
;
572 if (last
->cookie
&& inode
->i_op
->put_link
) {
573 inode
->i_op
->put_link(inode
, last
->cookie
);
579 static void terminate_walk(struct nameidata
*nd
)
582 if (!(nd
->flags
& LOOKUP_RCU
)) {
585 for (i
= 0; i
< nd
->depth
; i
++)
586 path_put(&nd
->stack
[i
].link
);
588 nd
->flags
&= ~LOOKUP_RCU
;
589 if (!(nd
->flags
& LOOKUP_ROOT
))
596 /* path_put is needed afterwards regardless of success or failure */
597 static bool legitimize_path(struct nameidata
*nd
,
598 struct path
*path
, unsigned seq
)
600 int res
= __legitimize_mnt(path
->mnt
, nd
->m_seq
);
607 if (unlikely(!lockref_get_not_dead(&path
->dentry
->d_lockref
))) {
611 return !read_seqcount_retry(&path
->dentry
->d_seq
, seq
);
614 static bool legitimize_links(struct nameidata
*nd
)
617 for (i
= 0; i
< nd
->depth
; i
++) {
618 struct saved
*last
= nd
->stack
+ i
;
619 if (unlikely(!legitimize_path(nd
, &last
->link
, last
->seq
))) {
629 * Path walking has 2 modes, rcu-walk and ref-walk (see
630 * Documentation/filesystems/path-lookup.txt). In situations when we can't
631 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
632 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
633 * mode. Refcounts are grabbed at the last known good point before rcu-walk
634 * got stuck, so ref-walk may continue from there. If this is not successful
635 * (eg. a seqcount has changed), then failure is returned and it's up to caller
636 * to restart the path walk from the beginning in ref-walk mode.
640 * unlazy_walk - try to switch to ref-walk mode.
641 * @nd: nameidata pathwalk data
642 * @dentry: child of nd->path.dentry or NULL
643 * @seq: seq number to check dentry against
644 * Returns: 0 on success, -ECHILD on failure
646 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
647 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
648 * @nd or NULL. Must be called from rcu-walk context.
649 * Nothing should touch nameidata between unlazy_walk() failure and
652 static int unlazy_walk(struct nameidata
*nd
, struct dentry
*dentry
, unsigned seq
)
654 struct dentry
*parent
= nd
->path
.dentry
;
656 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
658 nd
->flags
&= ~LOOKUP_RCU
;
659 if (unlikely(!legitimize_links(nd
)))
661 if (unlikely(!legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
)))
663 if (unlikely(!lockref_get_not_dead(&parent
->d_lockref
)))
667 * For a negative lookup, the lookup sequence point is the parents
668 * sequence point, and it only needs to revalidate the parent dentry.
670 * For a positive lookup, we need to move both the parent and the
671 * dentry from the RCU domain to be properly refcounted. And the
672 * sequence number in the dentry validates *both* dentry counters,
673 * since we checked the sequence number of the parent after we got
674 * the child sequence number. So we know the parent must still
675 * be valid if the child sequence number is still valid.
678 if (read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
680 BUG_ON(nd
->inode
!= parent
->d_inode
);
682 if (!lockref_get_not_dead(&dentry
->d_lockref
))
684 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
689 * Sequence counts matched. Now make sure that the root is
690 * still valid and get it if required.
692 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
693 if (unlikely(!legitimize_path(nd
, &nd
->root
, nd
->root_seq
))) {
710 nd
->path
.dentry
= NULL
;
714 if (!(nd
->flags
& LOOKUP_ROOT
))
719 static int unlazy_link(struct nameidata
*nd
, struct path
*link
, unsigned seq
)
721 if (unlikely(!legitimize_path(nd
, link
, seq
))) {
724 nd
->flags
&= ~LOOKUP_RCU
;
726 nd
->path
.dentry
= NULL
;
727 if (!(nd
->flags
& LOOKUP_ROOT
))
730 } else if (likely(unlazy_walk(nd
, NULL
, 0)) == 0) {
737 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
739 return dentry
->d_op
->d_revalidate(dentry
, flags
);
743 * complete_walk - successful completion of path walk
744 * @nd: pointer nameidata
746 * If we had been in RCU mode, drop out of it and legitimize nd->path.
747 * Revalidate the final result, unless we'd already done that during
748 * the path walk or the filesystem doesn't ask for it. Return 0 on
749 * success, -error on failure. In case of failure caller does not
750 * need to drop nd->path.
752 static int complete_walk(struct nameidata
*nd
)
754 struct dentry
*dentry
= nd
->path
.dentry
;
757 if (nd
->flags
& LOOKUP_RCU
) {
758 if (!(nd
->flags
& LOOKUP_ROOT
))
760 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
764 if (likely(!(nd
->flags
& LOOKUP_JUMPED
)))
767 if (likely(!(dentry
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)))
770 status
= dentry
->d_op
->d_weak_revalidate(dentry
, nd
->flags
);
780 static void set_root(struct nameidata
*nd
)
782 get_fs_root(current
->fs
, &nd
->root
);
785 static unsigned set_root_rcu(struct nameidata
*nd
)
787 struct fs_struct
*fs
= current
->fs
;
791 seq
= read_seqcount_begin(&fs
->seq
);
793 nd
->root_seq
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
794 } while (read_seqcount_retry(&fs
->seq
, seq
));
798 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
801 if (path
->mnt
!= nd
->path
.mnt
)
805 static inline void path_to_nameidata(const struct path
*path
,
806 struct nameidata
*nd
)
808 if (!(nd
->flags
& LOOKUP_RCU
)) {
809 dput(nd
->path
.dentry
);
810 if (nd
->path
.mnt
!= path
->mnt
)
811 mntput(nd
->path
.mnt
);
813 nd
->path
.mnt
= path
->mnt
;
814 nd
->path
.dentry
= path
->dentry
;
818 * Helper to directly jump to a known parsed path from ->follow_link,
819 * caller must have taken a reference to path beforehand.
821 void nd_jump_link(struct path
*path
)
823 struct nameidata
*nd
= current
->nameidata
;
827 nd
->inode
= nd
->path
.dentry
->d_inode
;
828 nd
->flags
|= LOOKUP_JUMPED
;
831 static inline void put_link(struct nameidata
*nd
)
833 struct saved
*last
= nd
->stack
+ --nd
->depth
;
834 struct inode
*inode
= last
->inode
;
835 if (last
->cookie
&& inode
->i_op
->put_link
)
836 inode
->i_op
->put_link(inode
, last
->cookie
);
837 if (!(nd
->flags
& LOOKUP_RCU
))
838 path_put(&last
->link
);
841 int sysctl_protected_symlinks __read_mostly
= 0;
842 int sysctl_protected_hardlinks __read_mostly
= 0;
845 * may_follow_link - Check symlink following for unsafe situations
846 * @nd: nameidata pathwalk data
848 * In the case of the sysctl_protected_symlinks sysctl being enabled,
849 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
850 * in a sticky world-writable directory. This is to protect privileged
851 * processes from failing races against path names that may change out
852 * from under them by way of other users creating malicious symlinks.
853 * It will permit symlinks to be followed only when outside a sticky
854 * world-writable directory, or when the uid of the symlink and follower
855 * match, or when the directory owner matches the symlink's owner.
857 * Returns 0 if following the symlink is allowed, -ve on error.
859 static inline int may_follow_link(struct nameidata
*nd
)
861 const struct inode
*inode
;
862 const struct inode
*parent
;
864 if (!sysctl_protected_symlinks
)
867 /* Allowed if owner and follower match. */
868 inode
= nd
->stack
[0].inode
;
869 if (uid_eq(current_cred()->fsuid
, inode
->i_uid
))
872 /* Allowed if parent directory not sticky and world-writable. */
873 parent
= nd
->path
.dentry
->d_inode
;
874 if ((parent
->i_mode
& (S_ISVTX
|S_IWOTH
)) != (S_ISVTX
|S_IWOTH
))
877 /* Allowed if parent directory and link owner match. */
878 if (uid_eq(parent
->i_uid
, inode
->i_uid
))
881 if (nd
->flags
& LOOKUP_RCU
)
884 audit_log_link_denied("follow_link", &nd
->stack
[0].link
);
889 * safe_hardlink_source - Check for safe hardlink conditions
890 * @inode: the source inode to hardlink from
892 * Return false if at least one of the following conditions:
893 * - inode is not a regular file
895 * - inode is setgid and group-exec
896 * - access failure for read and write
898 * Otherwise returns true.
900 static bool safe_hardlink_source(struct inode
*inode
)
902 umode_t mode
= inode
->i_mode
;
904 /* Special files should not get pinned to the filesystem. */
908 /* Setuid files should not get pinned to the filesystem. */
912 /* Executable setgid files should not get pinned to the filesystem. */
913 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
))
916 /* Hardlinking to unreadable or unwritable sources is dangerous. */
917 if (inode_permission(inode
, MAY_READ
| MAY_WRITE
))
924 * may_linkat - Check permissions for creating a hardlink
925 * @link: the source to hardlink from
927 * Block hardlink when all of:
928 * - sysctl_protected_hardlinks enabled
929 * - fsuid does not match inode
930 * - hardlink source is unsafe (see safe_hardlink_source() above)
933 * Returns 0 if successful, -ve on error.
935 static int may_linkat(struct path
*link
)
937 const struct cred
*cred
;
940 if (!sysctl_protected_hardlinks
)
943 cred
= current_cred();
944 inode
= link
->dentry
->d_inode
;
946 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
947 * otherwise, it must be a safe source.
949 if (uid_eq(cred
->fsuid
, inode
->i_uid
) || safe_hardlink_source(inode
) ||
953 audit_log_link_denied("linkat", link
);
957 static __always_inline
958 const char *get_link(struct nameidata
*nd
)
960 struct saved
*last
= nd
->stack
+ nd
->depth
- 1;
961 struct dentry
*dentry
= last
->link
.dentry
;
962 struct inode
*inode
= last
->inode
;
966 if (!(nd
->flags
& LOOKUP_RCU
)) {
967 touch_atime(&last
->link
);
969 } else if (atime_needs_update(&last
->link
, inode
)) {
970 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
971 return ERR_PTR(-ECHILD
);
972 touch_atime(&last
->link
);
975 error
= security_inode_follow_link(dentry
, inode
,
976 nd
->flags
& LOOKUP_RCU
);
978 return ERR_PTR(error
);
980 nd
->last_type
= LAST_BIND
;
983 if (nd
->flags
& LOOKUP_RCU
) {
984 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
985 return ERR_PTR(-ECHILD
);
987 res
= inode
->i_op
->follow_link(dentry
, &last
->cookie
);
988 if (IS_ERR_OR_NULL(res
)) {
994 if (nd
->flags
& LOOKUP_RCU
) {
1000 nd
->inode
= d
->d_inode
;
1001 nd
->seq
= nd
->root_seq
;
1002 if (unlikely(read_seqcount_retry(&d
->d_seq
, nd
->seq
)))
1003 return ERR_PTR(-ECHILD
);
1007 path_put(&nd
->path
);
1008 nd
->path
= nd
->root
;
1009 path_get(&nd
->root
);
1010 nd
->inode
= nd
->path
.dentry
->d_inode
;
1012 nd
->flags
|= LOOKUP_JUMPED
;
1013 while (unlikely(*++res
== '/'))
1022 * follow_up - Find the mountpoint of path's vfsmount
1024 * Given a path, find the mountpoint of its source file system.
1025 * Replace @path with the path of the mountpoint in the parent mount.
1028 * Return 1 if we went up a level and 0 if we were already at the
1031 int follow_up(struct path
*path
)
1033 struct mount
*mnt
= real_mount(path
->mnt
);
1034 struct mount
*parent
;
1035 struct dentry
*mountpoint
;
1037 read_seqlock_excl(&mount_lock
);
1038 parent
= mnt
->mnt_parent
;
1039 if (parent
== mnt
) {
1040 read_sequnlock_excl(&mount_lock
);
1043 mntget(&parent
->mnt
);
1044 mountpoint
= dget(mnt
->mnt_mountpoint
);
1045 read_sequnlock_excl(&mount_lock
);
1047 path
->dentry
= mountpoint
;
1049 path
->mnt
= &parent
->mnt
;
1052 EXPORT_SYMBOL(follow_up
);
1055 * Perform an automount
1056 * - return -EISDIR to tell follow_managed() to stop and return the path we
1059 static int follow_automount(struct path
*path
, struct nameidata
*nd
,
1062 struct vfsmount
*mnt
;
1065 if (!path
->dentry
->d_op
|| !path
->dentry
->d_op
->d_automount
)
1068 /* We don't want to mount if someone's just doing a stat -
1069 * unless they're stat'ing a directory and appended a '/' to
1072 * We do, however, want to mount if someone wants to open or
1073 * create a file of any type under the mountpoint, wants to
1074 * traverse through the mountpoint or wants to open the
1075 * mounted directory. Also, autofs may mark negative dentries
1076 * as being automount points. These will need the attentions
1077 * of the daemon to instantiate them before they can be used.
1079 if (!(nd
->flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
1080 LOOKUP_OPEN
| LOOKUP_CREATE
| LOOKUP_AUTOMOUNT
)) &&
1081 path
->dentry
->d_inode
)
1084 nd
->total_link_count
++;
1085 if (nd
->total_link_count
>= 40)
1088 mnt
= path
->dentry
->d_op
->d_automount(path
);
1091 * The filesystem is allowed to return -EISDIR here to indicate
1092 * it doesn't want to automount. For instance, autofs would do
1093 * this so that its userspace daemon can mount on this dentry.
1095 * However, we can only permit this if it's a terminal point in
1096 * the path being looked up; if it wasn't then the remainder of
1097 * the path is inaccessible and we should say so.
1099 if (PTR_ERR(mnt
) == -EISDIR
&& (nd
->flags
& LOOKUP_PARENT
))
1101 return PTR_ERR(mnt
);
1104 if (!mnt
) /* mount collision */
1107 if (!*need_mntput
) {
1108 /* lock_mount() may release path->mnt on error */
1110 *need_mntput
= true;
1112 err
= finish_automount(mnt
, path
);
1116 /* Someone else made a mount here whilst we were busy */
1121 path
->dentry
= dget(mnt
->mnt_root
);
1130 * Handle a dentry that is managed in some way.
1131 * - Flagged for transit management (autofs)
1132 * - Flagged as mountpoint
1133 * - Flagged as automount point
1135 * This may only be called in refwalk mode.
1137 * Serialization is taken care of in namespace.c
1139 static int follow_managed(struct path
*path
, struct nameidata
*nd
)
1141 struct vfsmount
*mnt
= path
->mnt
; /* held by caller, must be left alone */
1143 bool need_mntput
= false;
1146 /* Given that we're not holding a lock here, we retain the value in a
1147 * local variable for each dentry as we look at it so that we don't see
1148 * the components of that value change under us */
1149 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1150 managed
&= DCACHE_MANAGED_DENTRY
,
1151 unlikely(managed
!= 0)) {
1152 /* Allow the filesystem to manage the transit without i_mutex
1154 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1155 BUG_ON(!path
->dentry
->d_op
);
1156 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1157 ret
= path
->dentry
->d_op
->d_manage(path
->dentry
, false);
1162 /* Transit to a mounted filesystem. */
1163 if (managed
& DCACHE_MOUNTED
) {
1164 struct vfsmount
*mounted
= lookup_mnt(path
);
1169 path
->mnt
= mounted
;
1170 path
->dentry
= dget(mounted
->mnt_root
);
1175 /* Something is mounted on this dentry in another
1176 * namespace and/or whatever was mounted there in this
1177 * namespace got unmounted before lookup_mnt() could
1181 /* Handle an automount point */
1182 if (managed
& DCACHE_NEED_AUTOMOUNT
) {
1183 ret
= follow_automount(path
, nd
, &need_mntput
);
1189 /* We didn't change the current path point */
1193 if (need_mntput
&& path
->mnt
== mnt
)
1198 nd
->flags
|= LOOKUP_JUMPED
;
1199 if (unlikely(ret
< 0))
1200 path_put_conditional(path
, nd
);
1204 int follow_down_one(struct path
*path
)
1206 struct vfsmount
*mounted
;
1208 mounted
= lookup_mnt(path
);
1212 path
->mnt
= mounted
;
1213 path
->dentry
= dget(mounted
->mnt_root
);
1218 EXPORT_SYMBOL(follow_down_one
);
1220 static inline int managed_dentry_rcu(struct dentry
*dentry
)
1222 return (dentry
->d_flags
& DCACHE_MANAGE_TRANSIT
) ?
1223 dentry
->d_op
->d_manage(dentry
, true) : 0;
1227 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1228 * we meet a managed dentry that would need blocking.
1230 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
,
1231 struct inode
**inode
, unsigned *seqp
)
1234 struct mount
*mounted
;
1236 * Don't forget we might have a non-mountpoint managed dentry
1237 * that wants to block transit.
1239 switch (managed_dentry_rcu(path
->dentry
)) {
1249 if (!d_mountpoint(path
->dentry
))
1250 return !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1252 mounted
= __lookup_mnt(path
->mnt
, path
->dentry
);
1255 path
->mnt
= &mounted
->mnt
;
1256 path
->dentry
= mounted
->mnt
.mnt_root
;
1257 nd
->flags
|= LOOKUP_JUMPED
;
1258 *seqp
= read_seqcount_begin(&path
->dentry
->d_seq
);
1260 * Update the inode too. We don't need to re-check the
1261 * dentry sequence number here after this d_inode read,
1262 * because a mount-point is always pinned.
1264 *inode
= path
->dentry
->d_inode
;
1266 return !read_seqretry(&mount_lock
, nd
->m_seq
) &&
1267 !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1270 static int follow_dotdot_rcu(struct nameidata
*nd
)
1272 struct inode
*inode
= nd
->inode
;
1277 if (path_equal(&nd
->path
, &nd
->root
))
1279 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1280 struct dentry
*old
= nd
->path
.dentry
;
1281 struct dentry
*parent
= old
->d_parent
;
1284 inode
= parent
->d_inode
;
1285 seq
= read_seqcount_begin(&parent
->d_seq
);
1286 if (unlikely(read_seqcount_retry(&old
->d_seq
, nd
->seq
)))
1288 nd
->path
.dentry
= parent
;
1292 struct mount
*mnt
= real_mount(nd
->path
.mnt
);
1293 struct mount
*mparent
= mnt
->mnt_parent
;
1294 struct dentry
*mountpoint
= mnt
->mnt_mountpoint
;
1295 struct inode
*inode2
= mountpoint
->d_inode
;
1296 unsigned seq
= read_seqcount_begin(&mountpoint
->d_seq
);
1297 if (unlikely(read_seqretry(&mount_lock
, nd
->m_seq
)))
1299 if (&mparent
->mnt
== nd
->path
.mnt
)
1301 /* we know that mountpoint was pinned */
1302 nd
->path
.dentry
= mountpoint
;
1303 nd
->path
.mnt
= &mparent
->mnt
;
1308 while (unlikely(d_mountpoint(nd
->path
.dentry
))) {
1309 struct mount
*mounted
;
1310 mounted
= __lookup_mnt(nd
->path
.mnt
, nd
->path
.dentry
);
1311 if (unlikely(read_seqretry(&mount_lock
, nd
->m_seq
)))
1315 nd
->path
.mnt
= &mounted
->mnt
;
1316 nd
->path
.dentry
= mounted
->mnt
.mnt_root
;
1317 inode
= nd
->path
.dentry
->d_inode
;
1318 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1325 * Follow down to the covering mount currently visible to userspace. At each
1326 * point, the filesystem owning that dentry may be queried as to whether the
1327 * caller is permitted to proceed or not.
1329 int follow_down(struct path
*path
)
1334 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1335 unlikely(managed
& DCACHE_MANAGED_DENTRY
)) {
1336 /* Allow the filesystem to manage the transit without i_mutex
1339 * We indicate to the filesystem if someone is trying to mount
1340 * something here. This gives autofs the chance to deny anyone
1341 * other than its daemon the right to mount on its
1344 * The filesystem may sleep at this point.
1346 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1347 BUG_ON(!path
->dentry
->d_op
);
1348 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1349 ret
= path
->dentry
->d_op
->d_manage(
1350 path
->dentry
, false);
1352 return ret
== -EISDIR
? 0 : ret
;
1355 /* Transit to a mounted filesystem. */
1356 if (managed
& DCACHE_MOUNTED
) {
1357 struct vfsmount
*mounted
= lookup_mnt(path
);
1362 path
->mnt
= mounted
;
1363 path
->dentry
= dget(mounted
->mnt_root
);
1367 /* Don't handle automount points here */
1372 EXPORT_SYMBOL(follow_down
);
1375 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1377 static void follow_mount(struct path
*path
)
1379 while (d_mountpoint(path
->dentry
)) {
1380 struct vfsmount
*mounted
= lookup_mnt(path
);
1385 path
->mnt
= mounted
;
1386 path
->dentry
= dget(mounted
->mnt_root
);
1390 static void follow_dotdot(struct nameidata
*nd
)
1396 struct dentry
*old
= nd
->path
.dentry
;
1398 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1399 nd
->path
.mnt
== nd
->root
.mnt
) {
1402 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1403 /* rare case of legitimate dget_parent()... */
1404 nd
->path
.dentry
= dget_parent(nd
->path
.dentry
);
1408 if (!follow_up(&nd
->path
))
1411 follow_mount(&nd
->path
);
1412 nd
->inode
= nd
->path
.dentry
->d_inode
;
1416 * This looks up the name in dcache, possibly revalidates the old dentry and
1417 * allocates a new one if not found or not valid. In the need_lookup argument
1418 * returns whether i_op->lookup is necessary.
1420 * dir->d_inode->i_mutex must be held
1422 static struct dentry
*lookup_dcache(struct qstr
*name
, struct dentry
*dir
,
1423 unsigned int flags
, bool *need_lookup
)
1425 struct dentry
*dentry
;
1428 *need_lookup
= false;
1429 dentry
= d_lookup(dir
, name
);
1431 if (dentry
->d_flags
& DCACHE_OP_REVALIDATE
) {
1432 error
= d_revalidate(dentry
, flags
);
1433 if (unlikely(error
<= 0)) {
1436 return ERR_PTR(error
);
1438 d_invalidate(dentry
);
1447 dentry
= d_alloc(dir
, name
);
1448 if (unlikely(!dentry
))
1449 return ERR_PTR(-ENOMEM
);
1451 *need_lookup
= true;
1457 * Call i_op->lookup on the dentry. The dentry must be negative and
1460 * dir->d_inode->i_mutex must be held
1462 static struct dentry
*lookup_real(struct inode
*dir
, struct dentry
*dentry
,
1467 /* Don't create child dentry for a dead directory. */
1468 if (unlikely(IS_DEADDIR(dir
))) {
1470 return ERR_PTR(-ENOENT
);
1473 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1474 if (unlikely(old
)) {
1481 static struct dentry
*__lookup_hash(struct qstr
*name
,
1482 struct dentry
*base
, unsigned int flags
)
1485 struct dentry
*dentry
;
1487 dentry
= lookup_dcache(name
, base
, flags
, &need_lookup
);
1491 return lookup_real(base
->d_inode
, dentry
, flags
);
1495 * It's more convoluted than I'd like it to be, but... it's still fairly
1496 * small and for now I'd prefer to have fast path as straight as possible.
1497 * It _is_ time-critical.
1499 static int lookup_fast(struct nameidata
*nd
,
1500 struct path
*path
, struct inode
**inode
,
1503 struct vfsmount
*mnt
= nd
->path
.mnt
;
1504 struct dentry
*dentry
, *parent
= nd
->path
.dentry
;
1510 * Rename seqlock is not required here because in the off chance
1511 * of a false negative due to a concurrent rename, we're going to
1512 * do the non-racy lookup, below.
1514 if (nd
->flags
& LOOKUP_RCU
) {
1517 dentry
= __d_lookup_rcu(parent
, &nd
->last
, &seq
);
1522 * This sequence count validates that the inode matches
1523 * the dentry name information from lookup.
1525 *inode
= d_backing_inode(dentry
);
1526 negative
= d_is_negative(dentry
);
1527 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
1533 * This sequence count validates that the parent had no
1534 * changes while we did the lookup of the dentry above.
1536 * The memory barrier in read_seqcount_begin of child is
1537 * enough, we can use __read_seqcount_retry here.
1539 if (__read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
1543 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
)) {
1544 status
= d_revalidate(dentry
, nd
->flags
);
1545 if (unlikely(status
<= 0)) {
1546 if (status
!= -ECHILD
)
1552 path
->dentry
= dentry
;
1553 if (likely(__follow_mount_rcu(nd
, path
, inode
, seqp
)))
1556 if (unlazy_walk(nd
, dentry
, seq
))
1559 dentry
= __d_lookup(parent
, &nd
->last
);
1562 if (unlikely(!dentry
))
1565 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
) && need_reval
)
1566 status
= d_revalidate(dentry
, nd
->flags
);
1567 if (unlikely(status
<= 0)) {
1572 d_invalidate(dentry
);
1577 if (unlikely(d_is_negative(dentry
))) {
1582 path
->dentry
= dentry
;
1583 err
= follow_managed(path
, nd
);
1585 *inode
= d_backing_inode(path
->dentry
);
1592 /* Fast lookup failed, do it the slow way */
1593 static int lookup_slow(struct nameidata
*nd
, struct path
*path
)
1595 struct dentry
*dentry
, *parent
;
1597 parent
= nd
->path
.dentry
;
1598 BUG_ON(nd
->inode
!= parent
->d_inode
);
1600 mutex_lock(&parent
->d_inode
->i_mutex
);
1601 dentry
= __lookup_hash(&nd
->last
, parent
, nd
->flags
);
1602 mutex_unlock(&parent
->d_inode
->i_mutex
);
1604 return PTR_ERR(dentry
);
1605 path
->mnt
= nd
->path
.mnt
;
1606 path
->dentry
= dentry
;
1607 return follow_managed(path
, nd
);
1610 static inline int may_lookup(struct nameidata
*nd
)
1612 if (nd
->flags
& LOOKUP_RCU
) {
1613 int err
= inode_permission(nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1616 if (unlazy_walk(nd
, NULL
, 0))
1619 return inode_permission(nd
->inode
, MAY_EXEC
);
1622 static inline int handle_dots(struct nameidata
*nd
, int type
)
1624 if (type
== LAST_DOTDOT
) {
1625 if (nd
->flags
& LOOKUP_RCU
) {
1626 return follow_dotdot_rcu(nd
);
1633 static int pick_link(struct nameidata
*nd
, struct path
*link
,
1634 struct inode
*inode
, unsigned seq
)
1638 if (unlikely(nd
->total_link_count
++ >= MAXSYMLINKS
)) {
1639 path_to_nameidata(link
, nd
);
1642 if (!(nd
->flags
& LOOKUP_RCU
)) {
1643 if (link
->mnt
== nd
->path
.mnt
)
1646 error
= nd_alloc_stack(nd
);
1647 if (unlikely(error
)) {
1648 if (error
== -ECHILD
) {
1649 if (unlikely(unlazy_link(nd
, link
, seq
)))
1651 error
= nd_alloc_stack(nd
);
1659 last
= nd
->stack
+ nd
->depth
++;
1661 last
->cookie
= NULL
;
1662 last
->inode
= inode
;
1668 * Do we need to follow links? We _really_ want to be able
1669 * to do this check without having to look at inode->i_op,
1670 * so we keep a cache of "no, this doesn't need follow_link"
1671 * for the common case.
1673 static inline int should_follow_link(struct nameidata
*nd
, struct path
*link
,
1675 struct inode
*inode
, unsigned seq
)
1677 if (likely(!d_is_symlink(link
->dentry
)))
1681 return pick_link(nd
, link
, inode
, seq
);
1684 enum {WALK_GET
= 1, WALK_PUT
= 2};
1686 static int walk_component(struct nameidata
*nd
, int flags
)
1689 struct inode
*inode
;
1693 * "." and ".." are special - ".." especially so because it has
1694 * to be able to know about the current root directory and
1695 * parent relationships.
1697 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
1698 err
= handle_dots(nd
, nd
->last_type
);
1699 if (flags
& WALK_PUT
)
1703 err
= lookup_fast(nd
, &path
, &inode
, &seq
);
1704 if (unlikely(err
)) {
1708 err
= lookup_slow(nd
, &path
);
1712 inode
= d_backing_inode(path
.dentry
);
1713 seq
= 0; /* we are already out of RCU mode */
1715 if (d_is_negative(path
.dentry
))
1719 if (flags
& WALK_PUT
)
1721 err
= should_follow_link(nd
, &path
, flags
& WALK_GET
, inode
, seq
);
1724 path_to_nameidata(&path
, nd
);
1730 path_to_nameidata(&path
, nd
);
1735 * We can do the critical dentry name comparison and hashing
1736 * operations one word at a time, but we are limited to:
1738 * - Architectures with fast unaligned word accesses. We could
1739 * do a "get_unaligned()" if this helps and is sufficiently
1742 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1743 * do not trap on the (extremely unlikely) case of a page
1744 * crossing operation.
1746 * - Furthermore, we need an efficient 64-bit compile for the
1747 * 64-bit case in order to generate the "number of bytes in
1748 * the final mask". Again, that could be replaced with a
1749 * efficient population count instruction or similar.
1751 #ifdef CONFIG_DCACHE_WORD_ACCESS
1753 #include <asm/word-at-a-time.h>
1757 static inline unsigned int fold_hash(unsigned long hash
)
1759 return hash_64(hash
, 32);
1762 #else /* 32-bit case */
1764 #define fold_hash(x) (x)
1768 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1770 unsigned long a
, mask
;
1771 unsigned long hash
= 0;
1774 a
= load_unaligned_zeropad(name
);
1775 if (len
< sizeof(unsigned long))
1779 name
+= sizeof(unsigned long);
1780 len
-= sizeof(unsigned long);
1784 mask
= bytemask_from_count(len
);
1787 return fold_hash(hash
);
1789 EXPORT_SYMBOL(full_name_hash
);
1792 * Calculate the length and hash of the path component, and
1793 * return the "hash_len" as the result.
1795 static inline u64
hash_name(const char *name
)
1797 unsigned long a
, b
, adata
, bdata
, mask
, hash
, len
;
1798 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
1801 len
= -sizeof(unsigned long);
1803 hash
= (hash
+ a
) * 9;
1804 len
+= sizeof(unsigned long);
1805 a
= load_unaligned_zeropad(name
+len
);
1806 b
= a
^ REPEAT_BYTE('/');
1807 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
1809 adata
= prep_zero_mask(a
, adata
, &constants
);
1810 bdata
= prep_zero_mask(b
, bdata
, &constants
);
1812 mask
= create_zero_mask(adata
| bdata
);
1814 hash
+= a
& zero_bytemask(mask
);
1815 len
+= find_zero(mask
);
1816 return hashlen_create(fold_hash(hash
), len
);
1821 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1823 unsigned long hash
= init_name_hash();
1825 hash
= partial_name_hash(*name
++, hash
);
1826 return end_name_hash(hash
);
1828 EXPORT_SYMBOL(full_name_hash
);
1831 * We know there's a real path component here of at least
1834 static inline u64
hash_name(const char *name
)
1836 unsigned long hash
= init_name_hash();
1837 unsigned long len
= 0, c
;
1839 c
= (unsigned char)*name
;
1842 hash
= partial_name_hash(c
, hash
);
1843 c
= (unsigned char)name
[len
];
1844 } while (c
&& c
!= '/');
1845 return hashlen_create(end_name_hash(hash
), len
);
1852 * This is the basic name resolution function, turning a pathname into
1853 * the final dentry. We expect 'base' to be positive and a directory.
1855 * Returns 0 and nd will have valid dentry and mnt on success.
1856 * Returns error and drops reference to input namei data on failure.
1858 static int link_path_walk(const char *name
, struct nameidata
*nd
)
1867 /* At this point we know we have a real path component. */
1872 err
= may_lookup(nd
);
1876 hash_len
= hash_name(name
);
1879 if (name
[0] == '.') switch (hashlen_len(hash_len
)) {
1881 if (name
[1] == '.') {
1883 nd
->flags
|= LOOKUP_JUMPED
;
1889 if (likely(type
== LAST_NORM
)) {
1890 struct dentry
*parent
= nd
->path
.dentry
;
1891 nd
->flags
&= ~LOOKUP_JUMPED
;
1892 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
1893 struct qstr
this = { { .hash_len
= hash_len
}, .name
= name
};
1894 err
= parent
->d_op
->d_hash(parent
, &this);
1897 hash_len
= this.hash_len
;
1902 nd
->last
.hash_len
= hash_len
;
1903 nd
->last
.name
= name
;
1904 nd
->last_type
= type
;
1906 name
+= hashlen_len(hash_len
);
1910 * If it wasn't NUL, we know it was '/'. Skip that
1911 * slash, and continue until no more slashes.
1915 } while (unlikely(*name
== '/'));
1916 if (unlikely(!*name
)) {
1918 /* pathname body, done */
1921 name
= nd
->stack
[nd
->depth
- 1].name
;
1922 /* trailing symlink, done */
1925 /* last component of nested symlink */
1926 err
= walk_component(nd
, WALK_GET
| WALK_PUT
);
1928 err
= walk_component(nd
, WALK_GET
);
1934 const char *s
= get_link(nd
);
1936 if (unlikely(IS_ERR(s
)))
1943 nd
->stack
[nd
->depth
- 1].name
= name
;
1948 if (unlikely(!d_can_lookup(nd
->path
.dentry
)))
1953 static const char *path_init(int dfd
, const struct filename
*name
,
1954 unsigned int flags
, struct nameidata
*nd
)
1957 const char *s
= name
->name
;
1959 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1960 nd
->flags
= flags
| LOOKUP_JUMPED
| LOOKUP_PARENT
;
1962 nd
->total_link_count
= 0;
1963 if (flags
& LOOKUP_ROOT
) {
1964 struct dentry
*root
= nd
->root
.dentry
;
1965 struct inode
*inode
= root
->d_inode
;
1967 if (!d_can_lookup(root
))
1968 return ERR_PTR(-ENOTDIR
);
1969 retval
= inode_permission(inode
, MAY_EXEC
);
1971 return ERR_PTR(retval
);
1973 nd
->path
= nd
->root
;
1975 if (flags
& LOOKUP_RCU
) {
1977 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1978 nd
->root_seq
= nd
->seq
;
1979 nd
->m_seq
= read_seqbegin(&mount_lock
);
1981 path_get(&nd
->path
);
1986 nd
->root
.mnt
= NULL
;
1988 nd
->m_seq
= read_seqbegin(&mount_lock
);
1990 if (flags
& LOOKUP_RCU
) {
1992 nd
->seq
= set_root_rcu(nd
);
1995 path_get(&nd
->root
);
1997 nd
->path
= nd
->root
;
1998 } else if (dfd
== AT_FDCWD
) {
1999 if (flags
& LOOKUP_RCU
) {
2000 struct fs_struct
*fs
= current
->fs
;
2006 seq
= read_seqcount_begin(&fs
->seq
);
2008 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2009 } while (read_seqcount_retry(&fs
->seq
, seq
));
2011 get_fs_pwd(current
->fs
, &nd
->path
);
2014 /* Caller must check execute permissions on the starting path component */
2015 struct fd f
= fdget_raw(dfd
);
2016 struct dentry
*dentry
;
2019 return ERR_PTR(-EBADF
);
2021 dentry
= f
.file
->f_path
.dentry
;
2024 if (!d_can_lookup(dentry
)) {
2026 return ERR_PTR(-ENOTDIR
);
2030 nd
->path
= f
.file
->f_path
;
2031 if (flags
& LOOKUP_RCU
) {
2033 nd
->inode
= nd
->path
.dentry
->d_inode
;
2034 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2036 path_get(&nd
->path
);
2037 nd
->inode
= nd
->path
.dentry
->d_inode
;
2043 nd
->inode
= nd
->path
.dentry
->d_inode
;
2044 if (!(flags
& LOOKUP_RCU
))
2046 if (likely(!read_seqcount_retry(&nd
->path
.dentry
->d_seq
, nd
->seq
)))
2048 if (!(nd
->flags
& LOOKUP_ROOT
))
2049 nd
->root
.mnt
= NULL
;
2051 return ERR_PTR(-ECHILD
);
2054 static void path_cleanup(struct nameidata
*nd
)
2056 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
2057 path_put(&nd
->root
);
2058 nd
->root
.mnt
= NULL
;
2062 static const char *trailing_symlink(struct nameidata
*nd
)
2065 int error
= may_follow_link(nd
);
2066 if (unlikely(error
))
2067 return ERR_PTR(error
);
2068 nd
->flags
|= LOOKUP_PARENT
;
2069 nd
->stack
[0].name
= NULL
;
2074 static inline int lookup_last(struct nameidata
*nd
)
2076 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
2077 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2079 nd
->flags
&= ~LOOKUP_PARENT
;
2080 return walk_component(nd
,
2081 nd
->flags
& LOOKUP_FOLLOW
2083 ? WALK_PUT
| WALK_GET
2088 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2089 static int path_lookupat(int dfd
, const struct filename
*name
, unsigned flags
,
2090 struct nameidata
*nd
, struct path
*path
)
2092 const char *s
= path_init(dfd
, name
, flags
, nd
);
2097 while (!(err
= link_path_walk(s
, nd
))
2098 && ((err
= lookup_last(nd
)) > 0)) {
2099 s
= trailing_symlink(nd
);
2106 err
= complete_walk(nd
);
2108 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
)
2109 if (!d_can_lookup(nd
->path
.dentry
))
2113 nd
->path
.mnt
= NULL
;
2114 nd
->path
.dentry
= NULL
;
2121 static int filename_lookup(int dfd
, struct filename
*name
, unsigned flags
,
2122 struct path
*path
, struct path
*root
)
2125 struct nameidata nd
, *saved_nd
;
2127 return PTR_ERR(name
);
2128 saved_nd
= set_nameidata(&nd
);
2129 if (unlikely(root
)) {
2131 flags
|= LOOKUP_ROOT
;
2133 retval
= path_lookupat(dfd
, name
, flags
| LOOKUP_RCU
, &nd
, path
);
2134 if (unlikely(retval
== -ECHILD
))
2135 retval
= path_lookupat(dfd
, name
, flags
, &nd
, path
);
2136 if (unlikely(retval
== -ESTALE
))
2137 retval
= path_lookupat(dfd
, name
, flags
| LOOKUP_REVAL
,
2140 if (likely(!retval
))
2141 audit_inode(name
, path
->dentry
, flags
& LOOKUP_PARENT
);
2142 restore_nameidata(saved_nd
);
2147 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2148 static int path_parentat(int dfd
, const struct filename
*name
,
2149 unsigned int flags
, struct nameidata
*nd
,
2150 struct path
*parent
)
2152 const char *s
= path_init(dfd
, name
, flags
, nd
);
2156 err
= link_path_walk(s
, nd
);
2158 err
= complete_walk(nd
);
2161 nd
->path
.mnt
= NULL
;
2162 nd
->path
.dentry
= NULL
;
2169 static struct filename
*filename_parentat(int dfd
, struct filename
*name
,
2170 unsigned int flags
, struct path
*parent
,
2171 struct qstr
*last
, int *type
)
2174 struct nameidata nd
, *saved_nd
;
2178 saved_nd
= set_nameidata(&nd
);
2179 retval
= path_parentat(dfd
, name
, flags
| LOOKUP_RCU
, &nd
, parent
);
2180 if (unlikely(retval
== -ECHILD
))
2181 retval
= path_parentat(dfd
, name
, flags
, &nd
, parent
);
2182 if (unlikely(retval
== -ESTALE
))
2183 retval
= path_parentat(dfd
, name
, flags
| LOOKUP_REVAL
,
2185 if (likely(!retval
)) {
2187 *type
= nd
.last_type
;
2188 audit_inode(name
, parent
->dentry
, LOOKUP_PARENT
);
2191 name
= ERR_PTR(retval
);
2193 restore_nameidata(saved_nd
);
2197 /* does lookup, returns the object with parent locked */
2198 struct dentry
*kern_path_locked(const char *name
, struct path
*path
)
2200 struct filename
*filename
;
2205 filename
= filename_parentat(AT_FDCWD
, getname_kernel(name
), 0, path
,
2207 if (IS_ERR(filename
))
2208 return ERR_CAST(filename
);
2209 if (unlikely(type
!= LAST_NORM
)) {
2212 return ERR_PTR(-EINVAL
);
2214 mutex_lock_nested(&path
->dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2215 d
= __lookup_hash(&last
, path
->dentry
, 0);
2217 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
2224 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
2226 return filename_lookup(AT_FDCWD
, getname_kernel(name
),
2229 EXPORT_SYMBOL(kern_path
);
2232 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2233 * @dentry: pointer to dentry of the base directory
2234 * @mnt: pointer to vfs mount of the base directory
2235 * @name: pointer to file name
2236 * @flags: lookup flags
2237 * @path: pointer to struct path to fill
2239 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
2240 const char *name
, unsigned int flags
,
2243 struct path root
= {.mnt
= mnt
, .dentry
= dentry
};
2244 /* the first argument of filename_lookup() is ignored with root */
2245 return filename_lookup(AT_FDCWD
, getname_kernel(name
),
2246 flags
, path
, &root
);
2248 EXPORT_SYMBOL(vfs_path_lookup
);
2251 * lookup_one_len - filesystem helper to lookup single pathname component
2252 * @name: pathname component to lookup
2253 * @base: base directory to lookup from
2254 * @len: maximum length @len should be interpreted to
2256 * Note that this routine is purely a helper for filesystem usage and should
2257 * not be called by generic code.
2259 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2265 WARN_ON_ONCE(!mutex_is_locked(&base
->d_inode
->i_mutex
));
2269 this.hash
= full_name_hash(name
, len
);
2271 return ERR_PTR(-EACCES
);
2273 if (unlikely(name
[0] == '.')) {
2274 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2275 return ERR_PTR(-EACCES
);
2279 c
= *(const unsigned char *)name
++;
2280 if (c
== '/' || c
== '\0')
2281 return ERR_PTR(-EACCES
);
2284 * See if the low-level filesystem might want
2285 * to use its own hash..
2287 if (base
->d_flags
& DCACHE_OP_HASH
) {
2288 int err
= base
->d_op
->d_hash(base
, &this);
2290 return ERR_PTR(err
);
2293 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
2295 return ERR_PTR(err
);
2297 return __lookup_hash(&this, base
, 0);
2299 EXPORT_SYMBOL(lookup_one_len
);
2301 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
2302 struct path
*path
, int *empty
)
2304 return filename_lookup(dfd
, getname_flags(name
, flags
, empty
),
2308 int user_path_at(int dfd
, const char __user
*name
, unsigned flags
,
2311 return user_path_at_empty(dfd
, name
, flags
, path
, NULL
);
2313 EXPORT_SYMBOL(user_path_at
);
2316 * NB: most callers don't do anything directly with the reference to the
2317 * to struct filename, but the nd->last pointer points into the name string
2318 * allocated by getname. So we must hold the reference to it until all
2319 * path-walking is complete.
2321 static struct filename
*
2322 user_path_parent(int dfd
, const char __user
*path
,
2323 struct path
*parent
,
2328 /* only LOOKUP_REVAL is allowed in extra flags */
2329 return filename_parentat(dfd
, getname(path
), flags
& LOOKUP_REVAL
,
2330 parent
, last
, type
);
2334 * mountpoint_last - look up last component for umount
2335 * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
2336 * @path: pointer to container for result
2338 * This is a special lookup_last function just for umount. In this case, we
2339 * need to resolve the path without doing any revalidation.
2341 * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
2342 * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
2343 * in almost all cases, this lookup will be served out of the dcache. The only
2344 * cases where it won't are if nd->last refers to a symlink or the path is
2345 * bogus and it doesn't exist.
2348 * -error: if there was an error during lookup. This includes -ENOENT if the
2349 * lookup found a negative dentry. The nd->path reference will also be
2352 * 0: if we successfully resolved nd->path and found it to not to be a
2353 * symlink that needs to be followed. "path" will also be populated.
2354 * The nd->path reference will also be put.
2356 * 1: if we successfully resolved nd->last and found it to be a symlink
2357 * that needs to be followed. "path" will be populated with the path
2358 * to the link, and nd->path will *not* be put.
2361 mountpoint_last(struct nameidata
*nd
, struct path
*path
)
2364 struct dentry
*dentry
;
2365 struct dentry
*dir
= nd
->path
.dentry
;
2367 /* If we're in rcuwalk, drop out of it to handle last component */
2368 if (nd
->flags
& LOOKUP_RCU
) {
2369 if (unlazy_walk(nd
, NULL
, 0))
2373 nd
->flags
&= ~LOOKUP_PARENT
;
2375 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
2376 error
= handle_dots(nd
, nd
->last_type
);
2379 dentry
= dget(nd
->path
.dentry
);
2383 mutex_lock(&dir
->d_inode
->i_mutex
);
2384 dentry
= d_lookup(dir
, &nd
->last
);
2387 * No cached dentry. Mounted dentries are pinned in the cache,
2388 * so that means that this dentry is probably a symlink or the
2389 * path doesn't actually point to a mounted dentry.
2391 dentry
= d_alloc(dir
, &nd
->last
);
2393 mutex_unlock(&dir
->d_inode
->i_mutex
);
2396 dentry
= lookup_real(dir
->d_inode
, dentry
, nd
->flags
);
2397 if (IS_ERR(dentry
)) {
2398 mutex_unlock(&dir
->d_inode
->i_mutex
);
2399 return PTR_ERR(dentry
);
2402 mutex_unlock(&dir
->d_inode
->i_mutex
);
2405 if (d_is_negative(dentry
)) {
2411 path
->dentry
= dentry
;
2412 path
->mnt
= nd
->path
.mnt
;
2413 error
= should_follow_link(nd
, path
, nd
->flags
& LOOKUP_FOLLOW
,
2414 d_backing_inode(dentry
), 0);
2415 if (unlikely(error
))
2423 * path_mountpoint - look up a path to be umounted
2424 * @dfd: directory file descriptor to start walk from
2425 * @name: full pathname to walk
2426 * @path: pointer to container for result
2427 * @flags: lookup flags
2429 * Look up the given name, but don't attempt to revalidate the last component.
2430 * Returns 0 and "path" will be valid on success; Returns error otherwise.
2433 path_mountpoint(int dfd
, const struct filename
*name
, struct path
*path
,
2434 struct nameidata
*nd
, unsigned int flags
)
2436 const char *s
= path_init(dfd
, name
, flags
, nd
);
2440 while (!(err
= link_path_walk(s
, nd
)) &&
2441 (err
= mountpoint_last(nd
, path
)) > 0) {
2442 s
= trailing_symlink(nd
);
2454 filename_mountpoint(int dfd
, struct filename
*name
, struct path
*path
,
2457 struct nameidata nd
, *saved
;
2460 return PTR_ERR(name
);
2461 saved
= set_nameidata(&nd
);
2462 error
= path_mountpoint(dfd
, name
, path
, &nd
, flags
| LOOKUP_RCU
);
2463 if (unlikely(error
== -ECHILD
))
2464 error
= path_mountpoint(dfd
, name
, path
, &nd
, flags
);
2465 if (unlikely(error
== -ESTALE
))
2466 error
= path_mountpoint(dfd
, name
, path
, &nd
, flags
| LOOKUP_REVAL
);
2468 audit_inode(name
, path
->dentry
, 0);
2469 restore_nameidata(saved
);
2475 * user_path_mountpoint_at - lookup a path from userland in order to umount it
2476 * @dfd: directory file descriptor
2477 * @name: pathname from userland
2478 * @flags: lookup flags
2479 * @path: pointer to container to hold result
2481 * A umount is a special case for path walking. We're not actually interested
2482 * in the inode in this situation, and ESTALE errors can be a problem. We
2483 * simply want track down the dentry and vfsmount attached at the mountpoint
2484 * and avoid revalidating the last component.
2486 * Returns 0 and populates "path" on success.
2489 user_path_mountpoint_at(int dfd
, const char __user
*name
, unsigned int flags
,
2492 return filename_mountpoint(dfd
, getname(name
), path
, flags
);
2496 kern_path_mountpoint(int dfd
, const char *name
, struct path
*path
,
2499 return filename_mountpoint(dfd
, getname_kernel(name
), path
, flags
);
2501 EXPORT_SYMBOL(kern_path_mountpoint
);
2503 int __check_sticky(struct inode
*dir
, struct inode
*inode
)
2505 kuid_t fsuid
= current_fsuid();
2507 if (uid_eq(inode
->i_uid
, fsuid
))
2509 if (uid_eq(dir
->i_uid
, fsuid
))
2511 return !capable_wrt_inode_uidgid(inode
, CAP_FOWNER
);
2513 EXPORT_SYMBOL(__check_sticky
);
2516 * Check whether we can remove a link victim from directory dir, check
2517 * whether the type of victim is right.
2518 * 1. We can't do it if dir is read-only (done in permission())
2519 * 2. We should have write and exec permissions on dir
2520 * 3. We can't remove anything from append-only dir
2521 * 4. We can't do anything with immutable dir (done in permission())
2522 * 5. If the sticky bit on dir is set we should either
2523 * a. be owner of dir, or
2524 * b. be owner of victim, or
2525 * c. have CAP_FOWNER capability
2526 * 6. If the victim is append-only or immutable we can't do antyhing with
2527 * links pointing to it.
2528 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2529 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2530 * 9. We can't remove a root or mountpoint.
2531 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
2532 * nfs_async_unlink().
2534 static int may_delete(struct inode
*dir
, struct dentry
*victim
, bool isdir
)
2536 struct inode
*inode
= d_backing_inode(victim
);
2539 if (d_is_negative(victim
))
2543 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
2544 audit_inode_child(dir
, victim
, AUDIT_TYPE_CHILD_DELETE
);
2546 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2552 if (check_sticky(dir
, inode
) || IS_APPEND(inode
) ||
2553 IS_IMMUTABLE(inode
) || IS_SWAPFILE(inode
))
2556 if (!d_is_dir(victim
))
2558 if (IS_ROOT(victim
))
2560 } else if (d_is_dir(victim
))
2562 if (IS_DEADDIR(dir
))
2564 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2569 /* Check whether we can create an object with dentry child in directory
2571 * 1. We can't do it if child already exists (open has special treatment for
2572 * this case, but since we are inlined it's OK)
2573 * 2. We can't do it if dir is read-only (done in permission())
2574 * 3. We should have write and exec permissions on dir
2575 * 4. We can't do it if dir is immutable (done in permission())
2577 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
2579 audit_inode_child(dir
, child
, AUDIT_TYPE_CHILD_CREATE
);
2582 if (IS_DEADDIR(dir
))
2584 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2588 * p1 and p2 should be directories on the same fs.
2590 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2595 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2599 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2601 p
= d_ancestor(p2
, p1
);
2603 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2604 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2608 p
= d_ancestor(p1
, p2
);
2610 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2611 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2615 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2616 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT2
);
2619 EXPORT_SYMBOL(lock_rename
);
2621 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
2623 mutex_unlock(&p1
->d_inode
->i_mutex
);
2625 mutex_unlock(&p2
->d_inode
->i_mutex
);
2626 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2629 EXPORT_SYMBOL(unlock_rename
);
2631 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
2634 int error
= may_create(dir
, dentry
);
2638 if (!dir
->i_op
->create
)
2639 return -EACCES
; /* shouldn't it be ENOSYS? */
2642 error
= security_inode_create(dir
, dentry
, mode
);
2645 error
= dir
->i_op
->create(dir
, dentry
, mode
, want_excl
);
2647 fsnotify_create(dir
, dentry
);
2650 EXPORT_SYMBOL(vfs_create
);
2652 static int may_open(struct path
*path
, int acc_mode
, int flag
)
2654 struct dentry
*dentry
= path
->dentry
;
2655 struct inode
*inode
= dentry
->d_inode
;
2665 switch (inode
->i_mode
& S_IFMT
) {
2669 if (acc_mode
& MAY_WRITE
)
2674 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
2683 error
= inode_permission(inode
, acc_mode
);
2688 * An append-only file must be opened in append mode for writing.
2690 if (IS_APPEND(inode
)) {
2691 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
2697 /* O_NOATIME can only be set by the owner or superuser */
2698 if (flag
& O_NOATIME
&& !inode_owner_or_capable(inode
))
2704 static int handle_truncate(struct file
*filp
)
2706 struct path
*path
= &filp
->f_path
;
2707 struct inode
*inode
= path
->dentry
->d_inode
;
2708 int error
= get_write_access(inode
);
2712 * Refuse to truncate files with mandatory locks held on them.
2714 error
= locks_verify_locked(filp
);
2716 error
= security_path_truncate(path
);
2718 error
= do_truncate(path
->dentry
, 0,
2719 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
2722 put_write_access(inode
);
2726 static inline int open_to_namei_flags(int flag
)
2728 if ((flag
& O_ACCMODE
) == 3)
2733 static int may_o_create(struct path
*dir
, struct dentry
*dentry
, umode_t mode
)
2735 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
2739 error
= inode_permission(dir
->dentry
->d_inode
, MAY_WRITE
| MAY_EXEC
);
2743 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
2747 * Attempt to atomically look up, create and open a file from a negative
2750 * Returns 0 if successful. The file will have been created and attached to
2751 * @file by the filesystem calling finish_open().
2753 * Returns 1 if the file was looked up only or didn't need creating. The
2754 * caller will need to perform the open themselves. @path will have been
2755 * updated to point to the new dentry. This may be negative.
2757 * Returns an error code otherwise.
2759 static int atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
2760 struct path
*path
, struct file
*file
,
2761 const struct open_flags
*op
,
2762 bool got_write
, bool need_lookup
,
2765 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
2766 unsigned open_flag
= open_to_namei_flags(op
->open_flag
);
2770 int create_error
= 0;
2771 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
2774 BUG_ON(dentry
->d_inode
);
2776 /* Don't create child dentry for a dead directory. */
2777 if (unlikely(IS_DEADDIR(dir
))) {
2783 if ((open_flag
& O_CREAT
) && !IS_POSIXACL(dir
))
2784 mode
&= ~current_umask();
2786 excl
= (open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
);
2788 open_flag
&= ~O_TRUNC
;
2791 * Checking write permission is tricky, bacuse we don't know if we are
2792 * going to actually need it: O_CREAT opens should work as long as the
2793 * file exists. But checking existence breaks atomicity. The trick is
2794 * to check access and if not granted clear O_CREAT from the flags.
2796 * Another problem is returing the "right" error value (e.g. for an
2797 * O_EXCL open we want to return EEXIST not EROFS).
2799 if (((open_flag
& (O_CREAT
| O_TRUNC
)) ||
2800 (open_flag
& O_ACCMODE
) != O_RDONLY
) && unlikely(!got_write
)) {
2801 if (!(open_flag
& O_CREAT
)) {
2803 * No O_CREATE -> atomicity not a requirement -> fall
2804 * back to lookup + open
2807 } else if (open_flag
& (O_EXCL
| O_TRUNC
)) {
2808 /* Fall back and fail with the right error */
2809 create_error
= -EROFS
;
2812 /* No side effects, safe to clear O_CREAT */
2813 create_error
= -EROFS
;
2814 open_flag
&= ~O_CREAT
;
2818 if (open_flag
& O_CREAT
) {
2819 error
= may_o_create(&nd
->path
, dentry
, mode
);
2821 create_error
= error
;
2822 if (open_flag
& O_EXCL
)
2824 open_flag
&= ~O_CREAT
;
2828 if (nd
->flags
& LOOKUP_DIRECTORY
)
2829 open_flag
|= O_DIRECTORY
;
2831 file
->f_path
.dentry
= DENTRY_NOT_SET
;
2832 file
->f_path
.mnt
= nd
->path
.mnt
;
2833 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
, open_flag
, mode
,
2836 if (create_error
&& error
== -ENOENT
)
2837 error
= create_error
;
2841 if (error
) { /* returned 1, that is */
2842 if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
2846 if (file
->f_path
.dentry
) {
2848 dentry
= file
->f_path
.dentry
;
2850 if (*opened
& FILE_CREATED
)
2851 fsnotify_create(dir
, dentry
);
2852 if (!dentry
->d_inode
) {
2853 WARN_ON(*opened
& FILE_CREATED
);
2855 error
= create_error
;
2859 if (excl
&& !(*opened
& FILE_CREATED
)) {
2868 * We didn't have the inode before the open, so check open permission
2871 acc_mode
= op
->acc_mode
;
2872 if (*opened
& FILE_CREATED
) {
2873 WARN_ON(!(open_flag
& O_CREAT
));
2874 fsnotify_create(dir
, dentry
);
2875 acc_mode
= MAY_OPEN
;
2877 error
= may_open(&file
->f_path
, acc_mode
, open_flag
);
2887 dentry
= lookup_real(dir
, dentry
, nd
->flags
);
2889 return PTR_ERR(dentry
);
2892 int open_flag
= op
->open_flag
;
2894 error
= create_error
;
2895 if ((open_flag
& O_EXCL
)) {
2896 if (!dentry
->d_inode
)
2898 } else if (!dentry
->d_inode
) {
2900 } else if ((open_flag
& O_TRUNC
) &&
2904 /* will fail later, go on to get the right error */
2908 path
->dentry
= dentry
;
2909 path
->mnt
= nd
->path
.mnt
;
2914 * Look up and maybe create and open the last component.
2916 * Must be called with i_mutex held on parent.
2918 * Returns 0 if the file was successfully atomically created (if necessary) and
2919 * opened. In this case the file will be returned attached to @file.
2921 * Returns 1 if the file was not completely opened at this time, though lookups
2922 * and creations will have been performed and the dentry returned in @path will
2923 * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
2924 * specified then a negative dentry may be returned.
2926 * An error code is returned otherwise.
2928 * FILE_CREATE will be set in @*opened if the dentry was created and will be
2929 * cleared otherwise prior to returning.
2931 static int lookup_open(struct nameidata
*nd
, struct path
*path
,
2933 const struct open_flags
*op
,
2934 bool got_write
, int *opened
)
2936 struct dentry
*dir
= nd
->path
.dentry
;
2937 struct inode
*dir_inode
= dir
->d_inode
;
2938 struct dentry
*dentry
;
2942 *opened
&= ~FILE_CREATED
;
2943 dentry
= lookup_dcache(&nd
->last
, dir
, nd
->flags
, &need_lookup
);
2945 return PTR_ERR(dentry
);
2947 /* Cached positive dentry: will open in f_op->open */
2948 if (!need_lookup
&& dentry
->d_inode
)
2951 if ((nd
->flags
& LOOKUP_OPEN
) && dir_inode
->i_op
->atomic_open
) {
2952 return atomic_open(nd
, dentry
, path
, file
, op
, got_write
,
2953 need_lookup
, opened
);
2957 BUG_ON(dentry
->d_inode
);
2959 dentry
= lookup_real(dir_inode
, dentry
, nd
->flags
);
2961 return PTR_ERR(dentry
);
2964 /* Negative dentry, just create the file */
2965 if (!dentry
->d_inode
&& (op
->open_flag
& O_CREAT
)) {
2966 umode_t mode
= op
->mode
;
2967 if (!IS_POSIXACL(dir
->d_inode
))
2968 mode
&= ~current_umask();
2970 * This write is needed to ensure that a
2971 * rw->ro transition does not occur between
2972 * the time when the file is created and when
2973 * a permanent write count is taken through
2974 * the 'struct file' in finish_open().
2980 *opened
|= FILE_CREATED
;
2981 error
= security_path_mknod(&nd
->path
, dentry
, mode
, 0);
2984 error
= vfs_create(dir
->d_inode
, dentry
, mode
,
2985 nd
->flags
& LOOKUP_EXCL
);
2990 path
->dentry
= dentry
;
2991 path
->mnt
= nd
->path
.mnt
;
3000 * Handle the last step of open()
3002 static int do_last(struct nameidata
*nd
,
3003 struct file
*file
, const struct open_flags
*op
,
3004 int *opened
, struct filename
*name
)
3006 struct dentry
*dir
= nd
->path
.dentry
;
3007 int open_flag
= op
->open_flag
;
3008 bool will_truncate
= (open_flag
& O_TRUNC
) != 0;
3009 bool got_write
= false;
3010 int acc_mode
= op
->acc_mode
;
3012 struct inode
*inode
;
3013 struct path save_parent
= { .dentry
= NULL
, .mnt
= NULL
};
3015 bool retried
= false;
3018 nd
->flags
&= ~LOOKUP_PARENT
;
3019 nd
->flags
|= op
->intent
;
3021 if (nd
->last_type
!= LAST_NORM
) {
3022 error
= handle_dots(nd
, nd
->last_type
);
3023 if (unlikely(error
))
3028 if (!(open_flag
& O_CREAT
)) {
3029 if (nd
->last
.name
[nd
->last
.len
])
3030 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
3031 /* we _can_ be in RCU mode here */
3032 error
= lookup_fast(nd
, &path
, &inode
, &seq
);
3039 BUG_ON(nd
->inode
!= dir
->d_inode
);
3041 /* create side of things */
3043 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
3044 * has been cleared when we got to the last component we are
3047 error
= complete_walk(nd
);
3051 audit_inode(name
, dir
, LOOKUP_PARENT
);
3052 /* trailing slashes? */
3053 if (unlikely(nd
->last
.name
[nd
->last
.len
]))
3058 if (op
->open_flag
& (O_CREAT
| O_TRUNC
| O_WRONLY
| O_RDWR
)) {
3059 error
= mnt_want_write(nd
->path
.mnt
);
3063 * do _not_ fail yet - we might not need that or fail with
3064 * a different error; let lookup_open() decide; we'll be
3065 * dropping this one anyway.
3068 mutex_lock(&dir
->d_inode
->i_mutex
);
3069 error
= lookup_open(nd
, &path
, file
, op
, got_write
, opened
);
3070 mutex_unlock(&dir
->d_inode
->i_mutex
);
3076 if ((*opened
& FILE_CREATED
) ||
3077 !S_ISREG(file_inode(file
)->i_mode
))
3078 will_truncate
= false;
3080 audit_inode(name
, file
->f_path
.dentry
, 0);
3084 if (*opened
& FILE_CREATED
) {
3085 /* Don't check for write permission, don't truncate */
3086 open_flag
&= ~O_TRUNC
;
3087 will_truncate
= false;
3088 acc_mode
= MAY_OPEN
;
3089 path_to_nameidata(&path
, nd
);
3090 goto finish_open_created
;
3094 * create/update audit record if it already exists.
3096 if (d_is_positive(path
.dentry
))
3097 audit_inode(name
, path
.dentry
, 0);
3100 * If atomic_open() acquired write access it is dropped now due to
3101 * possible mount and symlink following (this might be optimized away if
3105 mnt_drop_write(nd
->path
.mnt
);
3109 if (unlikely((open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
))) {
3110 path_to_nameidata(&path
, nd
);
3114 error
= follow_managed(&path
, nd
);
3115 if (unlikely(error
< 0))
3118 BUG_ON(nd
->flags
& LOOKUP_RCU
);
3119 inode
= d_backing_inode(path
.dentry
);
3120 seq
= 0; /* out of RCU mode, so the value doesn't matter */
3121 if (unlikely(d_is_negative(path
.dentry
))) {
3122 path_to_nameidata(&path
, nd
);
3128 error
= should_follow_link(nd
, &path
, nd
->flags
& LOOKUP_FOLLOW
,
3130 if (unlikely(error
))
3133 if (unlikely(d_is_symlink(path
.dentry
)) && !(open_flag
& O_PATH
)) {
3134 path_to_nameidata(&path
, nd
);
3138 if ((nd
->flags
& LOOKUP_RCU
) || nd
->path
.mnt
!= path
.mnt
) {
3139 path_to_nameidata(&path
, nd
);
3141 save_parent
.dentry
= nd
->path
.dentry
;
3142 save_parent
.mnt
= mntget(path
.mnt
);
3143 nd
->path
.dentry
= path
.dentry
;
3148 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
3150 error
= complete_walk(nd
);
3152 path_put(&save_parent
);
3155 audit_inode(name
, nd
->path
.dentry
, 0);
3157 if ((open_flag
& O_CREAT
) && d_is_dir(nd
->path
.dentry
))
3160 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !d_can_lookup(nd
->path
.dentry
))
3162 if (!d_is_reg(nd
->path
.dentry
))
3163 will_truncate
= false;
3165 if (will_truncate
) {
3166 error
= mnt_want_write(nd
->path
.mnt
);
3171 finish_open_created
:
3172 error
= may_open(&nd
->path
, acc_mode
, open_flag
);
3176 BUG_ON(*opened
& FILE_OPENED
); /* once it's opened, it's opened */
3177 error
= vfs_open(&nd
->path
, file
, current_cred());
3179 *opened
|= FILE_OPENED
;
3181 if (error
== -EOPENSTALE
)
3186 error
= open_check_o_direct(file
);
3189 error
= ima_file_check(file
, op
->acc_mode
, *opened
);
3193 if (will_truncate
) {
3194 error
= handle_truncate(file
);
3200 mnt_drop_write(nd
->path
.mnt
);
3201 path_put(&save_parent
);
3209 /* If no saved parent or already retried then can't retry */
3210 if (!save_parent
.dentry
|| retried
)
3213 BUG_ON(save_parent
.dentry
!= dir
);
3214 path_put(&nd
->path
);
3215 nd
->path
= save_parent
;
3216 nd
->inode
= dir
->d_inode
;
3217 save_parent
.mnt
= NULL
;
3218 save_parent
.dentry
= NULL
;
3220 mnt_drop_write(nd
->path
.mnt
);
3227 static int do_tmpfile(int dfd
, struct filename
*pathname
,
3228 struct nameidata
*nd
, int flags
,
3229 const struct open_flags
*op
,
3230 struct file
*file
, int *opened
)
3232 static const struct qstr name
= QSTR_INIT("/", 1);
3233 struct dentry
*child
;
3236 int error
= path_lookupat(dfd
, pathname
,
3237 flags
| LOOKUP_DIRECTORY
, nd
, &path
);
3238 if (unlikely(error
))
3240 error
= mnt_want_write(path
.mnt
);
3241 if (unlikely(error
))
3243 dir
= path
.dentry
->d_inode
;
3244 /* we want directory to be writable */
3245 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
3248 if (!dir
->i_op
->tmpfile
) {
3249 error
= -EOPNOTSUPP
;
3252 child
= d_alloc(path
.dentry
, &name
);
3253 if (unlikely(!child
)) {
3258 path
.dentry
= child
;
3259 error
= dir
->i_op
->tmpfile(dir
, child
, op
->mode
);
3262 audit_inode(pathname
, child
, 0);
3263 /* Don't check for other permissions, the inode was just created */
3264 error
= may_open(&path
, MAY_OPEN
, op
->open_flag
);
3267 file
->f_path
.mnt
= path
.mnt
;
3268 error
= finish_open(file
, child
, NULL
, opened
);
3271 error
= open_check_o_direct(file
);
3274 } else if (!(op
->open_flag
& O_EXCL
)) {
3275 struct inode
*inode
= file_inode(file
);
3276 spin_lock(&inode
->i_lock
);
3277 inode
->i_state
|= I_LINKABLE
;
3278 spin_unlock(&inode
->i_lock
);
3281 mnt_drop_write(path
.mnt
);
3287 static struct file
*path_openat(int dfd
, struct filename
*pathname
,
3288 struct nameidata
*nd
, const struct open_flags
*op
, int flags
)
3295 file
= get_empty_filp();
3299 file
->f_flags
= op
->open_flag
;
3301 if (unlikely(file
->f_flags
& __O_TMPFILE
)) {
3302 error
= do_tmpfile(dfd
, pathname
, nd
, flags
, op
, file
, &opened
);
3306 s
= path_init(dfd
, pathname
, flags
, nd
);
3311 while (!(error
= link_path_walk(s
, nd
)) &&
3312 (error
= do_last(nd
, file
, op
, &opened
, pathname
)) > 0) {
3313 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
3314 s
= trailing_symlink(nd
);
3323 if (!(opened
& FILE_OPENED
)) {
3327 if (unlikely(error
)) {
3328 if (error
== -EOPENSTALE
) {
3329 if (flags
& LOOKUP_RCU
)
3334 file
= ERR_PTR(error
);
3339 struct file
*do_filp_open(int dfd
, struct filename
*pathname
,
3340 const struct open_flags
*op
)
3342 struct nameidata nd
, *saved_nd
= set_nameidata(&nd
);
3343 int flags
= op
->lookup_flags
;
3346 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
| LOOKUP_RCU
);
3347 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
3348 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
);
3349 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
3350 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
| LOOKUP_REVAL
);
3351 restore_nameidata(saved_nd
);
3355 struct file
*do_file_open_root(struct dentry
*dentry
, struct vfsmount
*mnt
,
3356 const char *name
, const struct open_flags
*op
)
3358 struct nameidata nd
, *saved_nd
;
3360 struct filename
*filename
;
3361 int flags
= op
->lookup_flags
| LOOKUP_ROOT
;
3364 nd
.root
.dentry
= dentry
;
3366 if (d_is_symlink(dentry
) && op
->intent
& LOOKUP_OPEN
)
3367 return ERR_PTR(-ELOOP
);
3369 filename
= getname_kernel(name
);
3370 if (unlikely(IS_ERR(filename
)))
3371 return ERR_CAST(filename
);
3373 saved_nd
= set_nameidata(&nd
);
3374 file
= path_openat(-1, filename
, &nd
, op
, flags
| LOOKUP_RCU
);
3375 if (unlikely(file
== ERR_PTR(-ECHILD
)))
3376 file
= path_openat(-1, filename
, &nd
, op
, flags
);
3377 if (unlikely(file
== ERR_PTR(-ESTALE
)))
3378 file
= path_openat(-1, filename
, &nd
, op
, flags
| LOOKUP_REVAL
);
3379 restore_nameidata(saved_nd
);
3384 static struct dentry
*filename_create(int dfd
, struct filename
*name
,
3385 struct path
*path
, unsigned int lookup_flags
)
3387 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
3392 bool is_dir
= (lookup_flags
& LOOKUP_DIRECTORY
);
3395 * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
3396 * other flags passed in are ignored!
3398 lookup_flags
&= LOOKUP_REVAL
;
3400 name
= filename_parentat(dfd
, name
, lookup_flags
, path
, &last
, &type
);
3402 return ERR_CAST(name
);
3405 * Yucky last component or no last component at all?
3406 * (foo/., foo/.., /////)
3408 if (unlikely(type
!= LAST_NORM
))
3411 /* don't fail immediately if it's r/o, at least try to report other errors */
3412 err2
= mnt_want_write(path
->mnt
);
3414 * Do the final lookup.
3416 lookup_flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
3417 mutex_lock_nested(&path
->dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3418 dentry
= __lookup_hash(&last
, path
->dentry
, lookup_flags
);
3423 if (d_is_positive(dentry
))
3427 * Special case - lookup gave negative, but... we had foo/bar/
3428 * From the vfs_mknod() POV we just have a negative dentry -
3429 * all is fine. Let's be bastards - you had / on the end, you've
3430 * been asking for (non-existent) directory. -ENOENT for you.
3432 if (unlikely(!is_dir
&& last
.name
[last
.len
])) {
3436 if (unlikely(err2
)) {
3444 dentry
= ERR_PTR(error
);
3446 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
3448 mnt_drop_write(path
->mnt
);
3455 struct dentry
*kern_path_create(int dfd
, const char *pathname
,
3456 struct path
*path
, unsigned int lookup_flags
)
3458 return filename_create(dfd
, getname_kernel(pathname
),
3459 path
, lookup_flags
);
3461 EXPORT_SYMBOL(kern_path_create
);
3463 void done_path_create(struct path
*path
, struct dentry
*dentry
)
3466 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
3467 mnt_drop_write(path
->mnt
);
3470 EXPORT_SYMBOL(done_path_create
);
3472 struct dentry
*user_path_create(int dfd
, const char __user
*pathname
,
3473 struct path
*path
, unsigned int lookup_flags
)
3475 return filename_create(dfd
, getname(pathname
), path
, lookup_flags
);
3477 EXPORT_SYMBOL(user_path_create
);
3479 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3481 int error
= may_create(dir
, dentry
);
3486 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
3489 if (!dir
->i_op
->mknod
)
3492 error
= devcgroup_inode_mknod(mode
, dev
);
3496 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
3500 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
3502 fsnotify_create(dir
, dentry
);
3505 EXPORT_SYMBOL(vfs_mknod
);
3507 static int may_mknod(umode_t mode
)
3509 switch (mode
& S_IFMT
) {
3515 case 0: /* zero mode translates to S_IFREG */
3524 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
3527 struct dentry
*dentry
;
3530 unsigned int lookup_flags
= 0;
3532 error
= may_mknod(mode
);
3536 dentry
= user_path_create(dfd
, filename
, &path
, lookup_flags
);
3538 return PTR_ERR(dentry
);
3540 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3541 mode
&= ~current_umask();
3542 error
= security_path_mknod(&path
, dentry
, mode
, dev
);
3545 switch (mode
& S_IFMT
) {
3546 case 0: case S_IFREG
:
3547 error
= vfs_create(path
.dentry
->d_inode
,dentry
,mode
,true);
3549 case S_IFCHR
: case S_IFBLK
:
3550 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,
3551 new_decode_dev(dev
));
3553 case S_IFIFO
: case S_IFSOCK
:
3554 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,0);
3558 done_path_create(&path
, dentry
);
3559 if (retry_estale(error
, lookup_flags
)) {
3560 lookup_flags
|= LOOKUP_REVAL
;
3566 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
3568 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
3571 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
3573 int error
= may_create(dir
, dentry
);
3574 unsigned max_links
= dir
->i_sb
->s_max_links
;
3579 if (!dir
->i_op
->mkdir
)
3582 mode
&= (S_IRWXUGO
|S_ISVTX
);
3583 error
= security_inode_mkdir(dir
, dentry
, mode
);
3587 if (max_links
&& dir
->i_nlink
>= max_links
)
3590 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
3592 fsnotify_mkdir(dir
, dentry
);
3595 EXPORT_SYMBOL(vfs_mkdir
);
3597 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, umode_t
, mode
)
3599 struct dentry
*dentry
;
3602 unsigned int lookup_flags
= LOOKUP_DIRECTORY
;
3605 dentry
= user_path_create(dfd
, pathname
, &path
, lookup_flags
);
3607 return PTR_ERR(dentry
);
3609 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3610 mode
&= ~current_umask();
3611 error
= security_path_mkdir(&path
, dentry
, mode
);
3613 error
= vfs_mkdir(path
.dentry
->d_inode
, dentry
, mode
);
3614 done_path_create(&path
, dentry
);
3615 if (retry_estale(error
, lookup_flags
)) {
3616 lookup_flags
|= LOOKUP_REVAL
;
3622 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, umode_t
, mode
)
3624 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
3628 * The dentry_unhash() helper will try to drop the dentry early: we
3629 * should have a usage count of 1 if we're the only user of this
3630 * dentry, and if that is true (possibly after pruning the dcache),
3631 * then we drop the dentry now.
3633 * A low-level filesystem can, if it choses, legally
3636 * if (!d_unhashed(dentry))
3639 * if it cannot handle the case of removing a directory
3640 * that is still in use by something else..
3642 void dentry_unhash(struct dentry
*dentry
)
3644 shrink_dcache_parent(dentry
);
3645 spin_lock(&dentry
->d_lock
);
3646 if (dentry
->d_lockref
.count
== 1)
3648 spin_unlock(&dentry
->d_lock
);
3650 EXPORT_SYMBOL(dentry_unhash
);
3652 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
3654 int error
= may_delete(dir
, dentry
, 1);
3659 if (!dir
->i_op
->rmdir
)
3663 mutex_lock(&dentry
->d_inode
->i_mutex
);
3666 if (is_local_mountpoint(dentry
))
3669 error
= security_inode_rmdir(dir
, dentry
);
3673 shrink_dcache_parent(dentry
);
3674 error
= dir
->i_op
->rmdir(dir
, dentry
);
3678 dentry
->d_inode
->i_flags
|= S_DEAD
;
3680 detach_mounts(dentry
);
3683 mutex_unlock(&dentry
->d_inode
->i_mutex
);
3689 EXPORT_SYMBOL(vfs_rmdir
);
3691 static long do_rmdir(int dfd
, const char __user
*pathname
)
3694 struct filename
*name
;
3695 struct dentry
*dentry
;
3699 unsigned int lookup_flags
= 0;
3701 name
= user_path_parent(dfd
, pathname
,
3702 &path
, &last
, &type
, lookup_flags
);
3704 return PTR_ERR(name
);
3718 error
= mnt_want_write(path
.mnt
);
3722 mutex_lock_nested(&path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3723 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3724 error
= PTR_ERR(dentry
);
3727 if (!dentry
->d_inode
) {
3731 error
= security_path_rmdir(&path
, dentry
);
3734 error
= vfs_rmdir(path
.dentry
->d_inode
, dentry
);
3738 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3739 mnt_drop_write(path
.mnt
);
3743 if (retry_estale(error
, lookup_flags
)) {
3744 lookup_flags
|= LOOKUP_REVAL
;
3750 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
3752 return do_rmdir(AT_FDCWD
, pathname
);
3756 * vfs_unlink - unlink a filesystem object
3757 * @dir: parent directory
3759 * @delegated_inode: returns victim inode, if the inode is delegated.
3761 * The caller must hold dir->i_mutex.
3763 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
3764 * return a reference to the inode in delegated_inode. The caller
3765 * should then break the delegation on that inode and retry. Because
3766 * breaking a delegation may take a long time, the caller should drop
3767 * dir->i_mutex before doing so.
3769 * Alternatively, a caller may pass NULL for delegated_inode. This may
3770 * be appropriate for callers that expect the underlying filesystem not
3771 * to be NFS exported.
3773 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
, struct inode
**delegated_inode
)
3775 struct inode
*target
= dentry
->d_inode
;
3776 int error
= may_delete(dir
, dentry
, 0);
3781 if (!dir
->i_op
->unlink
)
3784 mutex_lock(&target
->i_mutex
);
3785 if (is_local_mountpoint(dentry
))
3788 error
= security_inode_unlink(dir
, dentry
);
3790 error
= try_break_deleg(target
, delegated_inode
);
3793 error
= dir
->i_op
->unlink(dir
, dentry
);
3796 detach_mounts(dentry
);
3801 mutex_unlock(&target
->i_mutex
);
3803 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
3804 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
3805 fsnotify_link_count(target
);
3811 EXPORT_SYMBOL(vfs_unlink
);
3814 * Make sure that the actual truncation of the file will occur outside its
3815 * directory's i_mutex. Truncate can take a long time if there is a lot of
3816 * writeout happening, and we don't want to prevent access to the directory
3817 * while waiting on the I/O.
3819 static long do_unlinkat(int dfd
, const char __user
*pathname
)
3822 struct filename
*name
;
3823 struct dentry
*dentry
;
3827 struct inode
*inode
= NULL
;
3828 struct inode
*delegated_inode
= NULL
;
3829 unsigned int lookup_flags
= 0;
3831 name
= user_path_parent(dfd
, pathname
,
3832 &path
, &last
, &type
, lookup_flags
);
3834 return PTR_ERR(name
);
3837 if (type
!= LAST_NORM
)
3840 error
= mnt_want_write(path
.mnt
);
3844 mutex_lock_nested(&path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3845 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3846 error
= PTR_ERR(dentry
);
3847 if (!IS_ERR(dentry
)) {
3848 /* Why not before? Because we want correct error value */
3849 if (last
.name
[last
.len
])
3851 inode
= dentry
->d_inode
;
3852 if (d_is_negative(dentry
))
3855 error
= security_path_unlink(&path
, dentry
);
3858 error
= vfs_unlink(path
.dentry
->d_inode
, dentry
, &delegated_inode
);
3862 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3864 iput(inode
); /* truncate the inode here */
3866 if (delegated_inode
) {
3867 error
= break_deleg_wait(&delegated_inode
);
3871 mnt_drop_write(path
.mnt
);
3875 if (retry_estale(error
, lookup_flags
)) {
3876 lookup_flags
|= LOOKUP_REVAL
;
3883 if (d_is_negative(dentry
))
3885 else if (d_is_dir(dentry
))
3892 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
3894 if ((flag
& ~AT_REMOVEDIR
) != 0)
3897 if (flag
& AT_REMOVEDIR
)
3898 return do_rmdir(dfd
, pathname
);
3900 return do_unlinkat(dfd
, pathname
);
3903 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
3905 return do_unlinkat(AT_FDCWD
, pathname
);
3908 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
3910 int error
= may_create(dir
, dentry
);
3915 if (!dir
->i_op
->symlink
)
3918 error
= security_inode_symlink(dir
, dentry
, oldname
);
3922 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
3924 fsnotify_create(dir
, dentry
);
3927 EXPORT_SYMBOL(vfs_symlink
);
3929 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
3930 int, newdfd
, const char __user
*, newname
)
3933 struct filename
*from
;
3934 struct dentry
*dentry
;
3936 unsigned int lookup_flags
= 0;
3938 from
= getname(oldname
);
3940 return PTR_ERR(from
);
3942 dentry
= user_path_create(newdfd
, newname
, &path
, lookup_flags
);
3943 error
= PTR_ERR(dentry
);
3947 error
= security_path_symlink(&path
, dentry
, from
->name
);
3949 error
= vfs_symlink(path
.dentry
->d_inode
, dentry
, from
->name
);
3950 done_path_create(&path
, dentry
);
3951 if (retry_estale(error
, lookup_flags
)) {
3952 lookup_flags
|= LOOKUP_REVAL
;
3960 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
3962 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
3966 * vfs_link - create a new link
3967 * @old_dentry: object to be linked
3969 * @new_dentry: where to create the new link
3970 * @delegated_inode: returns inode needing a delegation break
3972 * The caller must hold dir->i_mutex
3974 * If vfs_link discovers a delegation on the to-be-linked file in need
3975 * of breaking, it will return -EWOULDBLOCK and return a reference to the
3976 * inode in delegated_inode. The caller should then break the delegation
3977 * and retry. Because breaking a delegation may take a long time, the
3978 * caller should drop the i_mutex before doing so.
3980 * Alternatively, a caller may pass NULL for delegated_inode. This may
3981 * be appropriate for callers that expect the underlying filesystem not
3982 * to be NFS exported.
3984 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
, struct inode
**delegated_inode
)
3986 struct inode
*inode
= old_dentry
->d_inode
;
3987 unsigned max_links
= dir
->i_sb
->s_max_links
;
3993 error
= may_create(dir
, new_dentry
);
3997 if (dir
->i_sb
!= inode
->i_sb
)
4001 * A link to an append-only or immutable file cannot be created.
4003 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
4005 if (!dir
->i_op
->link
)
4007 if (S_ISDIR(inode
->i_mode
))
4010 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
4014 mutex_lock(&inode
->i_mutex
);
4015 /* Make sure we don't allow creating hardlink to an unlinked file */
4016 if (inode
->i_nlink
== 0 && !(inode
->i_state
& I_LINKABLE
))
4018 else if (max_links
&& inode
->i_nlink
>= max_links
)
4021 error
= try_break_deleg(inode
, delegated_inode
);
4023 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
4026 if (!error
&& (inode
->i_state
& I_LINKABLE
)) {
4027 spin_lock(&inode
->i_lock
);
4028 inode
->i_state
&= ~I_LINKABLE
;
4029 spin_unlock(&inode
->i_lock
);
4031 mutex_unlock(&inode
->i_mutex
);
4033 fsnotify_link(dir
, inode
, new_dentry
);
4036 EXPORT_SYMBOL(vfs_link
);
4039 * Hardlinks are often used in delicate situations. We avoid
4040 * security-related surprises by not following symlinks on the
4043 * We don't follow them on the oldname either to be compatible
4044 * with linux 2.0, and to avoid hard-linking to directories
4045 * and other special files. --ADM
4047 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
4048 int, newdfd
, const char __user
*, newname
, int, flags
)
4050 struct dentry
*new_dentry
;
4051 struct path old_path
, new_path
;
4052 struct inode
*delegated_inode
= NULL
;
4056 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0)
4059 * To use null names we require CAP_DAC_READ_SEARCH
4060 * This ensures that not everyone will be able to create
4061 * handlink using the passed filedescriptor.
4063 if (flags
& AT_EMPTY_PATH
) {
4064 if (!capable(CAP_DAC_READ_SEARCH
))
4069 if (flags
& AT_SYMLINK_FOLLOW
)
4070 how
|= LOOKUP_FOLLOW
;
4072 error
= user_path_at(olddfd
, oldname
, how
, &old_path
);
4076 new_dentry
= user_path_create(newdfd
, newname
, &new_path
,
4077 (how
& LOOKUP_REVAL
));
4078 error
= PTR_ERR(new_dentry
);
4079 if (IS_ERR(new_dentry
))
4083 if (old_path
.mnt
!= new_path
.mnt
)
4085 error
= may_linkat(&old_path
);
4086 if (unlikely(error
))
4088 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
4091 error
= vfs_link(old_path
.dentry
, new_path
.dentry
->d_inode
, new_dentry
, &delegated_inode
);
4093 done_path_create(&new_path
, new_dentry
);
4094 if (delegated_inode
) {
4095 error
= break_deleg_wait(&delegated_inode
);
4097 path_put(&old_path
);
4101 if (retry_estale(error
, how
)) {
4102 path_put(&old_path
);
4103 how
|= LOOKUP_REVAL
;
4107 path_put(&old_path
);
4112 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
4114 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4118 * vfs_rename - rename a filesystem object
4119 * @old_dir: parent of source
4120 * @old_dentry: source
4121 * @new_dir: parent of destination
4122 * @new_dentry: destination
4123 * @delegated_inode: returns an inode needing a delegation break
4124 * @flags: rename flags
4126 * The caller must hold multiple mutexes--see lock_rename()).
4128 * If vfs_rename discovers a delegation in need of breaking at either
4129 * the source or destination, it will return -EWOULDBLOCK and return a
4130 * reference to the inode in delegated_inode. The caller should then
4131 * break the delegation and retry. Because breaking a delegation may
4132 * take a long time, the caller should drop all locks before doing
4135 * Alternatively, a caller may pass NULL for delegated_inode. This may
4136 * be appropriate for callers that expect the underlying filesystem not
4137 * to be NFS exported.
4139 * The worst of all namespace operations - renaming directory. "Perverted"
4140 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4142 * a) we can get into loop creation.
4143 * b) race potential - two innocent renames can create a loop together.
4144 * That's where 4.4 screws up. Current fix: serialization on
4145 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
4147 * c) we have to lock _four_ objects - parents and victim (if it exists),
4148 * and source (if it is not a directory).
4149 * And that - after we got ->i_mutex on parents (until then we don't know
4150 * whether the target exists). Solution: try to be smart with locking
4151 * order for inodes. We rely on the fact that tree topology may change
4152 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
4153 * move will be locked. Thus we can rank directories by the tree
4154 * (ancestors first) and rank all non-directories after them.
4155 * That works since everybody except rename does "lock parent, lookup,
4156 * lock child" and rename is under ->s_vfs_rename_mutex.
4157 * HOWEVER, it relies on the assumption that any object with ->lookup()
4158 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4159 * we'd better make sure that there's no link(2) for them.
4160 * d) conversion from fhandle to dentry may come in the wrong moment - when
4161 * we are removing the target. Solution: we will have to grab ->i_mutex
4162 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
4163 * ->i_mutex on parents, which works but leads to some truly excessive
4166 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
4167 struct inode
*new_dir
, struct dentry
*new_dentry
,
4168 struct inode
**delegated_inode
, unsigned int flags
)
4171 bool is_dir
= d_is_dir(old_dentry
);
4172 const unsigned char *old_name
;
4173 struct inode
*source
= old_dentry
->d_inode
;
4174 struct inode
*target
= new_dentry
->d_inode
;
4175 bool new_is_dir
= false;
4176 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
4178 if (source
== target
)
4181 error
= may_delete(old_dir
, old_dentry
, is_dir
);
4186 error
= may_create(new_dir
, new_dentry
);
4188 new_is_dir
= d_is_dir(new_dentry
);
4190 if (!(flags
& RENAME_EXCHANGE
))
4191 error
= may_delete(new_dir
, new_dentry
, is_dir
);
4193 error
= may_delete(new_dir
, new_dentry
, new_is_dir
);
4198 if (!old_dir
->i_op
->rename
&& !old_dir
->i_op
->rename2
)
4201 if (flags
&& !old_dir
->i_op
->rename2
)
4205 * If we are going to change the parent - check write permissions,
4206 * we'll need to flip '..'.
4208 if (new_dir
!= old_dir
) {
4210 error
= inode_permission(source
, MAY_WRITE
);
4214 if ((flags
& RENAME_EXCHANGE
) && new_is_dir
) {
4215 error
= inode_permission(target
, MAY_WRITE
);
4221 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
,
4226 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
4228 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4229 lock_two_nondirectories(source
, target
);
4231 mutex_lock(&target
->i_mutex
);
4234 if (is_local_mountpoint(old_dentry
) || is_local_mountpoint(new_dentry
))
4237 if (max_links
&& new_dir
!= old_dir
) {
4239 if (is_dir
&& !new_is_dir
&& new_dir
->i_nlink
>= max_links
)
4241 if ((flags
& RENAME_EXCHANGE
) && !is_dir
&& new_is_dir
&&
4242 old_dir
->i_nlink
>= max_links
)
4245 if (is_dir
&& !(flags
& RENAME_EXCHANGE
) && target
)
4246 shrink_dcache_parent(new_dentry
);
4248 error
= try_break_deleg(source
, delegated_inode
);
4252 if (target
&& !new_is_dir
) {
4253 error
= try_break_deleg(target
, delegated_inode
);
4257 if (!old_dir
->i_op
->rename2
) {
4258 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
,
4259 new_dir
, new_dentry
);
4261 WARN_ON(old_dir
->i_op
->rename
!= NULL
);
4262 error
= old_dir
->i_op
->rename2(old_dir
, old_dentry
,
4263 new_dir
, new_dentry
, flags
);
4268 if (!(flags
& RENAME_EXCHANGE
) && target
) {
4270 target
->i_flags
|= S_DEAD
;
4271 dont_mount(new_dentry
);
4272 detach_mounts(new_dentry
);
4274 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
)) {
4275 if (!(flags
& RENAME_EXCHANGE
))
4276 d_move(old_dentry
, new_dentry
);
4278 d_exchange(old_dentry
, new_dentry
);
4281 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4282 unlock_two_nondirectories(source
, target
);
4284 mutex_unlock(&target
->i_mutex
);
4287 fsnotify_move(old_dir
, new_dir
, old_name
, is_dir
,
4288 !(flags
& RENAME_EXCHANGE
) ? target
: NULL
, old_dentry
);
4289 if (flags
& RENAME_EXCHANGE
) {
4290 fsnotify_move(new_dir
, old_dir
, old_dentry
->d_name
.name
,
4291 new_is_dir
, NULL
, new_dentry
);
4294 fsnotify_oldname_free(old_name
);
4298 EXPORT_SYMBOL(vfs_rename
);
4300 SYSCALL_DEFINE5(renameat2
, int, olddfd
, const char __user
*, oldname
,
4301 int, newdfd
, const char __user
*, newname
, unsigned int, flags
)
4303 struct dentry
*old_dentry
, *new_dentry
;
4304 struct dentry
*trap
;
4305 struct path old_path
, new_path
;
4306 struct qstr old_last
, new_last
;
4307 int old_type
, new_type
;
4308 struct inode
*delegated_inode
= NULL
;
4309 struct filename
*from
;
4310 struct filename
*to
;
4311 unsigned int lookup_flags
= 0, target_flags
= LOOKUP_RENAME_TARGET
;
4312 bool should_retry
= false;
4315 if (flags
& ~(RENAME_NOREPLACE
| RENAME_EXCHANGE
| RENAME_WHITEOUT
))
4318 if ((flags
& (RENAME_NOREPLACE
| RENAME_WHITEOUT
)) &&
4319 (flags
& RENAME_EXCHANGE
))
4322 if ((flags
& RENAME_WHITEOUT
) && !capable(CAP_MKNOD
))
4325 if (flags
& RENAME_EXCHANGE
)
4329 from
= user_path_parent(olddfd
, oldname
,
4330 &old_path
, &old_last
, &old_type
, lookup_flags
);
4332 error
= PTR_ERR(from
);
4336 to
= user_path_parent(newdfd
, newname
,
4337 &new_path
, &new_last
, &new_type
, lookup_flags
);
4339 error
= PTR_ERR(to
);
4344 if (old_path
.mnt
!= new_path
.mnt
)
4348 if (old_type
!= LAST_NORM
)
4351 if (flags
& RENAME_NOREPLACE
)
4353 if (new_type
!= LAST_NORM
)
4356 error
= mnt_want_write(old_path
.mnt
);
4361 trap
= lock_rename(new_path
.dentry
, old_path
.dentry
);
4363 old_dentry
= __lookup_hash(&old_last
, old_path
.dentry
, lookup_flags
);
4364 error
= PTR_ERR(old_dentry
);
4365 if (IS_ERR(old_dentry
))
4367 /* source must exist */
4369 if (d_is_negative(old_dentry
))
4371 new_dentry
= __lookup_hash(&new_last
, new_path
.dentry
, lookup_flags
| target_flags
);
4372 error
= PTR_ERR(new_dentry
);
4373 if (IS_ERR(new_dentry
))
4376 if ((flags
& RENAME_NOREPLACE
) && d_is_positive(new_dentry
))
4378 if (flags
& RENAME_EXCHANGE
) {
4380 if (d_is_negative(new_dentry
))
4383 if (!d_is_dir(new_dentry
)) {
4385 if (new_last
.name
[new_last
.len
])
4389 /* unless the source is a directory trailing slashes give -ENOTDIR */
4390 if (!d_is_dir(old_dentry
)) {
4392 if (old_last
.name
[old_last
.len
])
4394 if (!(flags
& RENAME_EXCHANGE
) && new_last
.name
[new_last
.len
])
4397 /* source should not be ancestor of target */
4399 if (old_dentry
== trap
)
4401 /* target should not be an ancestor of source */
4402 if (!(flags
& RENAME_EXCHANGE
))
4404 if (new_dentry
== trap
)
4407 error
= security_path_rename(&old_path
, old_dentry
,
4408 &new_path
, new_dentry
, flags
);
4411 error
= vfs_rename(old_path
.dentry
->d_inode
, old_dentry
,
4412 new_path
.dentry
->d_inode
, new_dentry
,
4413 &delegated_inode
, flags
);
4419 unlock_rename(new_path
.dentry
, old_path
.dentry
);
4420 if (delegated_inode
) {
4421 error
= break_deleg_wait(&delegated_inode
);
4425 mnt_drop_write(old_path
.mnt
);
4427 if (retry_estale(error
, lookup_flags
))
4428 should_retry
= true;
4429 path_put(&new_path
);
4432 path_put(&old_path
);
4435 should_retry
= false;
4436 lookup_flags
|= LOOKUP_REVAL
;
4443 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
4444 int, newdfd
, const char __user
*, newname
)
4446 return sys_renameat2(olddfd
, oldname
, newdfd
, newname
, 0);
4449 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
4451 return sys_renameat2(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4454 int vfs_whiteout(struct inode
*dir
, struct dentry
*dentry
)
4456 int error
= may_create(dir
, dentry
);
4460 if (!dir
->i_op
->mknod
)
4463 return dir
->i_op
->mknod(dir
, dentry
,
4464 S_IFCHR
| WHITEOUT_MODE
, WHITEOUT_DEV
);
4466 EXPORT_SYMBOL(vfs_whiteout
);
4468 int readlink_copy(char __user
*buffer
, int buflen
, const char *link
)
4470 int len
= PTR_ERR(link
);
4475 if (len
> (unsigned) buflen
)
4477 if (copy_to_user(buffer
, link
, len
))
4482 EXPORT_SYMBOL(readlink_copy
);
4485 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
4486 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
4487 * using) it for any given inode is up to filesystem.
4489 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4492 struct inode
*inode
= d_inode(dentry
);
4493 const char *link
= inode
->i_link
;
4497 link
= inode
->i_op
->follow_link(dentry
, &cookie
);
4499 return PTR_ERR(link
);
4501 res
= readlink_copy(buffer
, buflen
, link
);
4502 if (inode
->i_op
->put_link
)
4503 inode
->i_op
->put_link(inode
, cookie
);
4506 EXPORT_SYMBOL(generic_readlink
);
4508 /* get the link contents into pagecache */
4509 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
4513 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
4514 page
= read_mapping_page(mapping
, 0, NULL
);
4519 nd_terminate_link(kaddr
, dentry
->d_inode
->i_size
, PAGE_SIZE
- 1);
4523 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4525 struct page
*page
= NULL
;
4526 int res
= readlink_copy(buffer
, buflen
, page_getlink(dentry
, &page
));
4529 page_cache_release(page
);
4533 EXPORT_SYMBOL(page_readlink
);
4535 const char *page_follow_link_light(struct dentry
*dentry
, void **cookie
)
4537 struct page
*page
= NULL
;
4538 char *res
= page_getlink(dentry
, &page
);
4543 EXPORT_SYMBOL(page_follow_link_light
);
4545 void page_put_link(struct inode
*unused
, void *cookie
)
4547 struct page
*page
= cookie
;
4549 page_cache_release(page
);
4551 EXPORT_SYMBOL(page_put_link
);
4554 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
4556 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
4558 struct address_space
*mapping
= inode
->i_mapping
;
4563 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
4565 flags
|= AOP_FLAG_NOFS
;
4568 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
4569 flags
, &page
, &fsdata
);
4573 kaddr
= kmap_atomic(page
);
4574 memcpy(kaddr
, symname
, len
-1);
4575 kunmap_atomic(kaddr
);
4577 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
4584 mark_inode_dirty(inode
);
4589 EXPORT_SYMBOL(__page_symlink
);
4591 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
4593 return __page_symlink(inode
, symname
, len
,
4594 !(mapping_gfp_mask(inode
->i_mapping
) & __GFP_FS
));
4596 EXPORT_SYMBOL(page_symlink
);
4598 const struct inode_operations page_symlink_inode_operations
= {
4599 .readlink
= generic_readlink
,
4600 .follow_link
= page_follow_link_light
,
4601 .put_link
= page_put_link
,
4603 EXPORT_SYMBOL(page_symlink_inode_operations
);