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 */
505 int total_link_count
;
512 } *stack
, internal
[EMBEDDED_LEVELS
];
513 struct filename
*name
;
514 struct nameidata
*saved
;
519 static void set_nameidata(struct nameidata
*p
, int dfd
, struct filename
*name
)
521 struct nameidata
*old
= current
->nameidata
;
522 p
->stack
= p
->internal
;
525 p
->total_link_count
= old
? old
->total_link_count
: 0;
527 current
->nameidata
= p
;
530 static void restore_nameidata(void)
532 struct nameidata
*now
= current
->nameidata
, *old
= now
->saved
;
534 current
->nameidata
= old
;
536 old
->total_link_count
= now
->total_link_count
;
537 if (now
->stack
!= now
->internal
) {
539 now
->stack
= now
->internal
;
543 static int __nd_alloc_stack(struct nameidata
*nd
)
547 if (nd
->flags
& LOOKUP_RCU
) {
548 p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
553 p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
558 memcpy(p
, nd
->internal
, sizeof(nd
->internal
));
564 * path_connected - Verify that a path->dentry is below path->mnt.mnt_root
565 * @path: nameidate to verify
567 * Rename can sometimes move a file or directory outside of a bind
568 * mount, path_connected allows those cases to be detected.
570 static bool path_connected(const struct path
*path
)
572 struct vfsmount
*mnt
= path
->mnt
;
574 /* Only bind mounts can have disconnected paths */
575 if (mnt
->mnt_root
== mnt
->mnt_sb
->s_root
)
578 return is_subdir(path
->dentry
, mnt
->mnt_root
);
581 static inline int nd_alloc_stack(struct nameidata
*nd
)
583 if (likely(nd
->depth
!= EMBEDDED_LEVELS
))
585 if (likely(nd
->stack
!= nd
->internal
))
587 return __nd_alloc_stack(nd
);
590 static void drop_links(struct nameidata
*nd
)
594 struct saved
*last
= nd
->stack
+ i
;
595 struct inode
*inode
= last
->inode
;
596 if (last
->cookie
&& inode
->i_op
->put_link
) {
597 inode
->i_op
->put_link(inode
, last
->cookie
);
603 static void terminate_walk(struct nameidata
*nd
)
606 if (!(nd
->flags
& LOOKUP_RCU
)) {
609 for (i
= 0; i
< nd
->depth
; i
++)
610 path_put(&nd
->stack
[i
].link
);
611 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
616 nd
->flags
&= ~LOOKUP_RCU
;
617 if (!(nd
->flags
& LOOKUP_ROOT
))
624 /* path_put is needed afterwards regardless of success or failure */
625 static bool legitimize_path(struct nameidata
*nd
,
626 struct path
*path
, unsigned seq
)
628 int res
= __legitimize_mnt(path
->mnt
, nd
->m_seq
);
635 if (unlikely(!lockref_get_not_dead(&path
->dentry
->d_lockref
))) {
639 return !read_seqcount_retry(&path
->dentry
->d_seq
, seq
);
642 static bool legitimize_links(struct nameidata
*nd
)
645 for (i
= 0; i
< nd
->depth
; i
++) {
646 struct saved
*last
= nd
->stack
+ i
;
647 if (unlikely(!legitimize_path(nd
, &last
->link
, last
->seq
))) {
657 * Path walking has 2 modes, rcu-walk and ref-walk (see
658 * Documentation/filesystems/path-lookup.txt). In situations when we can't
659 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
660 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
661 * mode. Refcounts are grabbed at the last known good point before rcu-walk
662 * got stuck, so ref-walk may continue from there. If this is not successful
663 * (eg. a seqcount has changed), then failure is returned and it's up to caller
664 * to restart the path walk from the beginning in ref-walk mode.
668 * unlazy_walk - try to switch to ref-walk mode.
669 * @nd: nameidata pathwalk data
670 * @dentry: child of nd->path.dentry or NULL
671 * @seq: seq number to check dentry against
672 * Returns: 0 on success, -ECHILD on failure
674 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
675 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
676 * @nd or NULL. Must be called from rcu-walk context.
677 * Nothing should touch nameidata between unlazy_walk() failure and
680 static int unlazy_walk(struct nameidata
*nd
, struct dentry
*dentry
, unsigned seq
)
682 struct dentry
*parent
= nd
->path
.dentry
;
684 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
686 nd
->flags
&= ~LOOKUP_RCU
;
687 if (unlikely(!legitimize_links(nd
)))
689 if (unlikely(!legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
)))
691 if (unlikely(!lockref_get_not_dead(&parent
->d_lockref
)))
695 * For a negative lookup, the lookup sequence point is the parents
696 * sequence point, and it only needs to revalidate the parent dentry.
698 * For a positive lookup, we need to move both the parent and the
699 * dentry from the RCU domain to be properly refcounted. And the
700 * sequence number in the dentry validates *both* dentry counters,
701 * since we checked the sequence number of the parent after we got
702 * the child sequence number. So we know the parent must still
703 * be valid if the child sequence number is still valid.
706 if (read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
708 BUG_ON(nd
->inode
!= parent
->d_inode
);
710 if (!lockref_get_not_dead(&dentry
->d_lockref
))
712 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
717 * Sequence counts matched. Now make sure that the root is
718 * still valid and get it if required.
720 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
721 if (unlikely(!legitimize_path(nd
, &nd
->root
, nd
->root_seq
))) {
738 nd
->path
.dentry
= NULL
;
742 if (!(nd
->flags
& LOOKUP_ROOT
))
747 static int unlazy_link(struct nameidata
*nd
, struct path
*link
, unsigned seq
)
749 if (unlikely(!legitimize_path(nd
, link
, seq
))) {
752 nd
->flags
&= ~LOOKUP_RCU
;
754 nd
->path
.dentry
= NULL
;
755 if (!(nd
->flags
& LOOKUP_ROOT
))
758 } else if (likely(unlazy_walk(nd
, NULL
, 0)) == 0) {
765 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
767 return dentry
->d_op
->d_revalidate(dentry
, flags
);
771 * complete_walk - successful completion of path walk
772 * @nd: pointer nameidata
774 * If we had been in RCU mode, drop out of it and legitimize nd->path.
775 * Revalidate the final result, unless we'd already done that during
776 * the path walk or the filesystem doesn't ask for it. Return 0 on
777 * success, -error on failure. In case of failure caller does not
778 * need to drop nd->path.
780 static int complete_walk(struct nameidata
*nd
)
782 struct dentry
*dentry
= nd
->path
.dentry
;
785 if (nd
->flags
& LOOKUP_RCU
) {
786 if (!(nd
->flags
& LOOKUP_ROOT
))
788 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
792 if (likely(!(nd
->flags
& LOOKUP_JUMPED
)))
795 if (likely(!(dentry
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)))
798 status
= dentry
->d_op
->d_weak_revalidate(dentry
, nd
->flags
);
808 static void set_root(struct nameidata
*nd
)
810 get_fs_root(current
->fs
, &nd
->root
);
813 static void set_root_rcu(struct nameidata
*nd
)
815 struct fs_struct
*fs
= current
->fs
;
819 seq
= read_seqcount_begin(&fs
->seq
);
821 nd
->root_seq
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
822 } while (read_seqcount_retry(&fs
->seq
, seq
));
825 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
828 if (path
->mnt
!= nd
->path
.mnt
)
832 static inline void path_to_nameidata(const struct path
*path
,
833 struct nameidata
*nd
)
835 if (!(nd
->flags
& LOOKUP_RCU
)) {
836 dput(nd
->path
.dentry
);
837 if (nd
->path
.mnt
!= path
->mnt
)
838 mntput(nd
->path
.mnt
);
840 nd
->path
.mnt
= path
->mnt
;
841 nd
->path
.dentry
= path
->dentry
;
845 * Helper to directly jump to a known parsed path from ->follow_link,
846 * caller must have taken a reference to path beforehand.
848 void nd_jump_link(struct path
*path
)
850 struct nameidata
*nd
= current
->nameidata
;
854 nd
->inode
= nd
->path
.dentry
->d_inode
;
855 nd
->flags
|= LOOKUP_JUMPED
;
858 static inline void put_link(struct nameidata
*nd
)
860 struct saved
*last
= nd
->stack
+ --nd
->depth
;
861 struct inode
*inode
= last
->inode
;
862 if (last
->cookie
&& inode
->i_op
->put_link
)
863 inode
->i_op
->put_link(inode
, last
->cookie
);
864 if (!(nd
->flags
& LOOKUP_RCU
))
865 path_put(&last
->link
);
868 int sysctl_protected_symlinks __read_mostly
= 0;
869 int sysctl_protected_hardlinks __read_mostly
= 0;
872 * may_follow_link - Check symlink following for unsafe situations
873 * @nd: nameidata pathwalk data
875 * In the case of the sysctl_protected_symlinks sysctl being enabled,
876 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
877 * in a sticky world-writable directory. This is to protect privileged
878 * processes from failing races against path names that may change out
879 * from under them by way of other users creating malicious symlinks.
880 * It will permit symlinks to be followed only when outside a sticky
881 * world-writable directory, or when the uid of the symlink and follower
882 * match, or when the directory owner matches the symlink's owner.
884 * Returns 0 if following the symlink is allowed, -ve on error.
886 static inline int may_follow_link(struct nameidata
*nd
)
888 const struct inode
*inode
;
889 const struct inode
*parent
;
891 if (!sysctl_protected_symlinks
)
894 /* Allowed if owner and follower match. */
895 inode
= nd
->stack
[0].inode
;
896 if (uid_eq(current_cred()->fsuid
, inode
->i_uid
))
899 /* Allowed if parent directory not sticky and world-writable. */
901 if ((parent
->i_mode
& (S_ISVTX
|S_IWOTH
)) != (S_ISVTX
|S_IWOTH
))
904 /* Allowed if parent directory and link owner match. */
905 if (uid_eq(parent
->i_uid
, inode
->i_uid
))
908 if (nd
->flags
& LOOKUP_RCU
)
911 audit_log_link_denied("follow_link", &nd
->stack
[0].link
);
916 * safe_hardlink_source - Check for safe hardlink conditions
917 * @inode: the source inode to hardlink from
919 * Return false if at least one of the following conditions:
920 * - inode is not a regular file
922 * - inode is setgid and group-exec
923 * - access failure for read and write
925 * Otherwise returns true.
927 static bool safe_hardlink_source(struct inode
*inode
)
929 umode_t mode
= inode
->i_mode
;
931 /* Special files should not get pinned to the filesystem. */
935 /* Setuid files should not get pinned to the filesystem. */
939 /* Executable setgid files should not get pinned to the filesystem. */
940 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
))
943 /* Hardlinking to unreadable or unwritable sources is dangerous. */
944 if (inode_permission(inode
, MAY_READ
| MAY_WRITE
))
951 * may_linkat - Check permissions for creating a hardlink
952 * @link: the source to hardlink from
954 * Block hardlink when all of:
955 * - sysctl_protected_hardlinks enabled
956 * - fsuid does not match inode
957 * - hardlink source is unsafe (see safe_hardlink_source() above)
958 * - not CAP_FOWNER in a namespace with the inode owner uid mapped
960 * Returns 0 if successful, -ve on error.
962 static int may_linkat(struct path
*link
)
966 if (!sysctl_protected_hardlinks
)
969 inode
= link
->dentry
->d_inode
;
971 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
972 * otherwise, it must be a safe source.
974 if (inode_owner_or_capable(inode
) || safe_hardlink_source(inode
))
977 audit_log_link_denied("linkat", link
);
981 static __always_inline
982 const char *get_link(struct nameidata
*nd
)
984 struct saved
*last
= nd
->stack
+ nd
->depth
- 1;
985 struct dentry
*dentry
= last
->link
.dentry
;
986 struct inode
*inode
= last
->inode
;
990 if (!(nd
->flags
& LOOKUP_RCU
)) {
991 touch_atime(&last
->link
);
993 } else if (atime_needs_update(&last
->link
, inode
)) {
994 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
995 return ERR_PTR(-ECHILD
);
996 touch_atime(&last
->link
);
999 error
= security_inode_follow_link(dentry
, inode
,
1000 nd
->flags
& LOOKUP_RCU
);
1001 if (unlikely(error
))
1002 return ERR_PTR(error
);
1004 nd
->last_type
= LAST_BIND
;
1005 res
= inode
->i_link
;
1007 if (nd
->flags
& LOOKUP_RCU
) {
1008 if (unlikely(unlazy_walk(nd
, NULL
, 0)))
1009 return ERR_PTR(-ECHILD
);
1011 res
= inode
->i_op
->follow_link(dentry
, &last
->cookie
);
1012 if (IS_ERR_OR_NULL(res
)) {
1013 last
->cookie
= NULL
;
1018 if (nd
->flags
& LOOKUP_RCU
) {
1022 nd
->path
= nd
->root
;
1023 d
= nd
->path
.dentry
;
1024 nd
->inode
= d
->d_inode
;
1025 nd
->seq
= nd
->root_seq
;
1026 if (unlikely(read_seqcount_retry(&d
->d_seq
, nd
->seq
)))
1027 return ERR_PTR(-ECHILD
);
1031 path_put(&nd
->path
);
1032 nd
->path
= nd
->root
;
1033 path_get(&nd
->root
);
1034 nd
->inode
= nd
->path
.dentry
->d_inode
;
1036 nd
->flags
|= LOOKUP_JUMPED
;
1037 while (unlikely(*++res
== '/'))
1046 * follow_up - Find the mountpoint of path's vfsmount
1048 * Given a path, find the mountpoint of its source file system.
1049 * Replace @path with the path of the mountpoint in the parent mount.
1052 * Return 1 if we went up a level and 0 if we were already at the
1055 int follow_up(struct path
*path
)
1057 struct mount
*mnt
= real_mount(path
->mnt
);
1058 struct mount
*parent
;
1059 struct dentry
*mountpoint
;
1061 read_seqlock_excl(&mount_lock
);
1062 parent
= mnt
->mnt_parent
;
1063 if (parent
== mnt
) {
1064 read_sequnlock_excl(&mount_lock
);
1067 mntget(&parent
->mnt
);
1068 mountpoint
= dget(mnt
->mnt_mountpoint
);
1069 read_sequnlock_excl(&mount_lock
);
1071 path
->dentry
= mountpoint
;
1073 path
->mnt
= &parent
->mnt
;
1076 EXPORT_SYMBOL(follow_up
);
1079 * Perform an automount
1080 * - return -EISDIR to tell follow_managed() to stop and return the path we
1083 static int follow_automount(struct path
*path
, struct nameidata
*nd
,
1086 struct vfsmount
*mnt
;
1089 if (!path
->dentry
->d_op
|| !path
->dentry
->d_op
->d_automount
)
1092 /* We don't want to mount if someone's just doing a stat -
1093 * unless they're stat'ing a directory and appended a '/' to
1096 * We do, however, want to mount if someone wants to open or
1097 * create a file of any type under the mountpoint, wants to
1098 * traverse through the mountpoint or wants to open the
1099 * mounted directory. Also, autofs may mark negative dentries
1100 * as being automount points. These will need the attentions
1101 * of the daemon to instantiate them before they can be used.
1103 if (!(nd
->flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
1104 LOOKUP_OPEN
| LOOKUP_CREATE
| LOOKUP_AUTOMOUNT
)) &&
1105 path
->dentry
->d_inode
)
1108 nd
->total_link_count
++;
1109 if (nd
->total_link_count
>= 40)
1112 mnt
= path
->dentry
->d_op
->d_automount(path
);
1115 * The filesystem is allowed to return -EISDIR here to indicate
1116 * it doesn't want to automount. For instance, autofs would do
1117 * this so that its userspace daemon can mount on this dentry.
1119 * However, we can only permit this if it's a terminal point in
1120 * the path being looked up; if it wasn't then the remainder of
1121 * the path is inaccessible and we should say so.
1123 if (PTR_ERR(mnt
) == -EISDIR
&& (nd
->flags
& LOOKUP_PARENT
))
1125 return PTR_ERR(mnt
);
1128 if (!mnt
) /* mount collision */
1131 if (!*need_mntput
) {
1132 /* lock_mount() may release path->mnt on error */
1134 *need_mntput
= true;
1136 err
= finish_automount(mnt
, path
);
1140 /* Someone else made a mount here whilst we were busy */
1145 path
->dentry
= dget(mnt
->mnt_root
);
1154 * Handle a dentry that is managed in some way.
1155 * - Flagged for transit management (autofs)
1156 * - Flagged as mountpoint
1157 * - Flagged as automount point
1159 * This may only be called in refwalk mode.
1161 * Serialization is taken care of in namespace.c
1163 static int follow_managed(struct path
*path
, struct nameidata
*nd
)
1165 struct vfsmount
*mnt
= path
->mnt
; /* held by caller, must be left alone */
1167 bool need_mntput
= false;
1170 /* Given that we're not holding a lock here, we retain the value in a
1171 * local variable for each dentry as we look at it so that we don't see
1172 * the components of that value change under us */
1173 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1174 managed
&= DCACHE_MANAGED_DENTRY
,
1175 unlikely(managed
!= 0)) {
1176 /* Allow the filesystem to manage the transit without i_mutex
1178 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1179 BUG_ON(!path
->dentry
->d_op
);
1180 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1181 ret
= path
->dentry
->d_op
->d_manage(path
->dentry
, false);
1186 /* Transit to a mounted filesystem. */
1187 if (managed
& DCACHE_MOUNTED
) {
1188 struct vfsmount
*mounted
= lookup_mnt(path
);
1193 path
->mnt
= mounted
;
1194 path
->dentry
= dget(mounted
->mnt_root
);
1199 /* Something is mounted on this dentry in another
1200 * namespace and/or whatever was mounted there in this
1201 * namespace got unmounted before lookup_mnt() could
1205 /* Handle an automount point */
1206 if (managed
& DCACHE_NEED_AUTOMOUNT
) {
1207 ret
= follow_automount(path
, nd
, &need_mntput
);
1213 /* We didn't change the current path point */
1217 if (need_mntput
&& path
->mnt
== mnt
)
1222 nd
->flags
|= LOOKUP_JUMPED
;
1223 if (unlikely(ret
< 0))
1224 path_put_conditional(path
, nd
);
1228 int follow_down_one(struct path
*path
)
1230 struct vfsmount
*mounted
;
1232 mounted
= lookup_mnt(path
);
1236 path
->mnt
= mounted
;
1237 path
->dentry
= dget(mounted
->mnt_root
);
1242 EXPORT_SYMBOL(follow_down_one
);
1244 static inline int managed_dentry_rcu(struct dentry
*dentry
)
1246 return (dentry
->d_flags
& DCACHE_MANAGE_TRANSIT
) ?
1247 dentry
->d_op
->d_manage(dentry
, true) : 0;
1251 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1252 * we meet a managed dentry that would need blocking.
1254 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
,
1255 struct inode
**inode
, unsigned *seqp
)
1258 struct mount
*mounted
;
1260 * Don't forget we might have a non-mountpoint managed dentry
1261 * that wants to block transit.
1263 switch (managed_dentry_rcu(path
->dentry
)) {
1273 if (!d_mountpoint(path
->dentry
))
1274 return !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1276 mounted
= __lookup_mnt(path
->mnt
, path
->dentry
);
1279 path
->mnt
= &mounted
->mnt
;
1280 path
->dentry
= mounted
->mnt
.mnt_root
;
1281 nd
->flags
|= LOOKUP_JUMPED
;
1282 *seqp
= read_seqcount_begin(&path
->dentry
->d_seq
);
1284 * Update the inode too. We don't need to re-check the
1285 * dentry sequence number here after this d_inode read,
1286 * because a mount-point is always pinned.
1288 *inode
= path
->dentry
->d_inode
;
1290 return !read_seqretry(&mount_lock
, nd
->m_seq
) &&
1291 !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1294 static int follow_dotdot_rcu(struct nameidata
*nd
)
1296 struct inode
*inode
= nd
->inode
;
1301 if (path_equal(&nd
->path
, &nd
->root
))
1303 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1304 struct dentry
*old
= nd
->path
.dentry
;
1305 struct dentry
*parent
= old
->d_parent
;
1308 inode
= parent
->d_inode
;
1309 seq
= read_seqcount_begin(&parent
->d_seq
);
1310 if (unlikely(read_seqcount_retry(&old
->d_seq
, nd
->seq
)))
1312 nd
->path
.dentry
= parent
;
1314 if (unlikely(!path_connected(&nd
->path
)))
1318 struct mount
*mnt
= real_mount(nd
->path
.mnt
);
1319 struct mount
*mparent
= mnt
->mnt_parent
;
1320 struct dentry
*mountpoint
= mnt
->mnt_mountpoint
;
1321 struct inode
*inode2
= mountpoint
->d_inode
;
1322 unsigned seq
= read_seqcount_begin(&mountpoint
->d_seq
);
1323 if (unlikely(read_seqretry(&mount_lock
, nd
->m_seq
)))
1325 if (&mparent
->mnt
== nd
->path
.mnt
)
1327 /* we know that mountpoint was pinned */
1328 nd
->path
.dentry
= mountpoint
;
1329 nd
->path
.mnt
= &mparent
->mnt
;
1334 while (unlikely(d_mountpoint(nd
->path
.dentry
))) {
1335 struct mount
*mounted
;
1336 mounted
= __lookup_mnt(nd
->path
.mnt
, nd
->path
.dentry
);
1337 if (unlikely(read_seqretry(&mount_lock
, nd
->m_seq
)))
1341 nd
->path
.mnt
= &mounted
->mnt
;
1342 nd
->path
.dentry
= mounted
->mnt
.mnt_root
;
1343 inode
= nd
->path
.dentry
->d_inode
;
1344 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1351 * Follow down to the covering mount currently visible to userspace. At each
1352 * point, the filesystem owning that dentry may be queried as to whether the
1353 * caller is permitted to proceed or not.
1355 int follow_down(struct path
*path
)
1360 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1361 unlikely(managed
& DCACHE_MANAGED_DENTRY
)) {
1362 /* Allow the filesystem to manage the transit without i_mutex
1365 * We indicate to the filesystem if someone is trying to mount
1366 * something here. This gives autofs the chance to deny anyone
1367 * other than its daemon the right to mount on its
1370 * The filesystem may sleep at this point.
1372 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1373 BUG_ON(!path
->dentry
->d_op
);
1374 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1375 ret
= path
->dentry
->d_op
->d_manage(
1376 path
->dentry
, false);
1378 return ret
== -EISDIR
? 0 : ret
;
1381 /* Transit to a mounted filesystem. */
1382 if (managed
& DCACHE_MOUNTED
) {
1383 struct vfsmount
*mounted
= lookup_mnt(path
);
1388 path
->mnt
= mounted
;
1389 path
->dentry
= dget(mounted
->mnt_root
);
1393 /* Don't handle automount points here */
1398 EXPORT_SYMBOL(follow_down
);
1401 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1403 static void follow_mount(struct path
*path
)
1405 while (d_mountpoint(path
->dentry
)) {
1406 struct vfsmount
*mounted
= lookup_mnt(path
);
1411 path
->mnt
= mounted
;
1412 path
->dentry
= dget(mounted
->mnt_root
);
1416 static int follow_dotdot(struct nameidata
*nd
)
1422 struct dentry
*old
= nd
->path
.dentry
;
1424 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1425 nd
->path
.mnt
== nd
->root
.mnt
) {
1428 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1429 /* rare case of legitimate dget_parent()... */
1430 nd
->path
.dentry
= dget_parent(nd
->path
.dentry
);
1432 if (unlikely(!path_connected(&nd
->path
)))
1436 if (!follow_up(&nd
->path
))
1439 follow_mount(&nd
->path
);
1440 nd
->inode
= nd
->path
.dentry
->d_inode
;
1445 * This looks up the name in dcache, possibly revalidates the old dentry and
1446 * allocates a new one if not found or not valid. In the need_lookup argument
1447 * returns whether i_op->lookup is necessary.
1449 * dir->d_inode->i_mutex must be held
1451 static struct dentry
*lookup_dcache(struct qstr
*name
, struct dentry
*dir
,
1452 unsigned int flags
, bool *need_lookup
)
1454 struct dentry
*dentry
;
1457 *need_lookup
= false;
1458 dentry
= d_lookup(dir
, name
);
1460 if (dentry
->d_flags
& DCACHE_OP_REVALIDATE
) {
1461 error
= d_revalidate(dentry
, flags
);
1462 if (unlikely(error
<= 0)) {
1465 return ERR_PTR(error
);
1467 d_invalidate(dentry
);
1476 dentry
= d_alloc(dir
, name
);
1477 if (unlikely(!dentry
))
1478 return ERR_PTR(-ENOMEM
);
1480 *need_lookup
= true;
1486 * Call i_op->lookup on the dentry. The dentry must be negative and
1489 * dir->d_inode->i_mutex must be held
1491 static struct dentry
*lookup_real(struct inode
*dir
, struct dentry
*dentry
,
1496 /* Don't create child dentry for a dead directory. */
1497 if (unlikely(IS_DEADDIR(dir
))) {
1499 return ERR_PTR(-ENOENT
);
1502 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1503 if (unlikely(old
)) {
1510 static struct dentry
*__lookup_hash(struct qstr
*name
,
1511 struct dentry
*base
, unsigned int flags
)
1514 struct dentry
*dentry
;
1516 dentry
= lookup_dcache(name
, base
, flags
, &need_lookup
);
1520 return lookup_real(base
->d_inode
, dentry
, flags
);
1524 * It's more convoluted than I'd like it to be, but... it's still fairly
1525 * small and for now I'd prefer to have fast path as straight as possible.
1526 * It _is_ time-critical.
1528 static int lookup_fast(struct nameidata
*nd
,
1529 struct path
*path
, struct inode
**inode
,
1532 struct vfsmount
*mnt
= nd
->path
.mnt
;
1533 struct dentry
*dentry
, *parent
= nd
->path
.dentry
;
1539 * Rename seqlock is not required here because in the off chance
1540 * of a false negative due to a concurrent rename, we're going to
1541 * do the non-racy lookup, below.
1543 if (nd
->flags
& LOOKUP_RCU
) {
1546 dentry
= __d_lookup_rcu(parent
, &nd
->last
, &seq
);
1551 * This sequence count validates that the inode matches
1552 * the dentry name information from lookup.
1554 *inode
= d_backing_inode(dentry
);
1555 negative
= d_is_negative(dentry
);
1556 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
1562 * This sequence count validates that the parent had no
1563 * changes while we did the lookup of the dentry above.
1565 * The memory barrier in read_seqcount_begin of child is
1566 * enough, we can use __read_seqcount_retry here.
1568 if (__read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
1572 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
)) {
1573 status
= d_revalidate(dentry
, nd
->flags
);
1574 if (unlikely(status
<= 0)) {
1575 if (status
!= -ECHILD
)
1581 path
->dentry
= dentry
;
1582 if (likely(__follow_mount_rcu(nd
, path
, inode
, seqp
)))
1585 if (unlazy_walk(nd
, dentry
, seq
))
1588 dentry
= __d_lookup(parent
, &nd
->last
);
1591 if (unlikely(!dentry
))
1594 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
) && need_reval
)
1595 status
= d_revalidate(dentry
, nd
->flags
);
1596 if (unlikely(status
<= 0)) {
1601 d_invalidate(dentry
);
1606 if (unlikely(d_is_negative(dentry
))) {
1611 path
->dentry
= dentry
;
1612 err
= follow_managed(path
, nd
);
1614 *inode
= d_backing_inode(path
->dentry
);
1621 /* Fast lookup failed, do it the slow way */
1622 static int lookup_slow(struct nameidata
*nd
, struct path
*path
)
1624 struct dentry
*dentry
, *parent
;
1626 parent
= nd
->path
.dentry
;
1627 BUG_ON(nd
->inode
!= parent
->d_inode
);
1629 mutex_lock(&parent
->d_inode
->i_mutex
);
1630 dentry
= __lookup_hash(&nd
->last
, parent
, nd
->flags
);
1631 mutex_unlock(&parent
->d_inode
->i_mutex
);
1633 return PTR_ERR(dentry
);
1634 path
->mnt
= nd
->path
.mnt
;
1635 path
->dentry
= dentry
;
1636 return follow_managed(path
, nd
);
1639 static inline int may_lookup(struct nameidata
*nd
)
1641 if (nd
->flags
& LOOKUP_RCU
) {
1642 int err
= inode_permission(nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1645 if (unlazy_walk(nd
, NULL
, 0))
1648 return inode_permission(nd
->inode
, MAY_EXEC
);
1651 static inline int handle_dots(struct nameidata
*nd
, int type
)
1653 if (type
== LAST_DOTDOT
) {
1654 if (nd
->flags
& LOOKUP_RCU
) {
1655 return follow_dotdot_rcu(nd
);
1657 return follow_dotdot(nd
);
1662 static int pick_link(struct nameidata
*nd
, struct path
*link
,
1663 struct inode
*inode
, unsigned seq
)
1667 if (unlikely(nd
->total_link_count
++ >= MAXSYMLINKS
)) {
1668 path_to_nameidata(link
, nd
);
1671 if (!(nd
->flags
& LOOKUP_RCU
)) {
1672 if (link
->mnt
== nd
->path
.mnt
)
1675 error
= nd_alloc_stack(nd
);
1676 if (unlikely(error
)) {
1677 if (error
== -ECHILD
) {
1678 if (unlikely(unlazy_link(nd
, link
, seq
)))
1680 error
= nd_alloc_stack(nd
);
1688 last
= nd
->stack
+ nd
->depth
++;
1690 last
->cookie
= NULL
;
1691 last
->inode
= inode
;
1697 * Do we need to follow links? We _really_ want to be able
1698 * to do this check without having to look at inode->i_op,
1699 * so we keep a cache of "no, this doesn't need follow_link"
1700 * for the common case.
1702 static inline int should_follow_link(struct nameidata
*nd
, struct path
*link
,
1704 struct inode
*inode
, unsigned seq
)
1706 if (likely(!d_is_symlink(link
->dentry
)))
1710 return pick_link(nd
, link
, inode
, seq
);
1713 enum {WALK_GET
= 1, WALK_PUT
= 2};
1715 static int walk_component(struct nameidata
*nd
, int flags
)
1718 struct inode
*inode
;
1722 * "." and ".." are special - ".." especially so because it has
1723 * to be able to know about the current root directory and
1724 * parent relationships.
1726 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
1727 err
= handle_dots(nd
, nd
->last_type
);
1728 if (flags
& WALK_PUT
)
1732 err
= lookup_fast(nd
, &path
, &inode
, &seq
);
1733 if (unlikely(err
)) {
1737 err
= lookup_slow(nd
, &path
);
1741 inode
= d_backing_inode(path
.dentry
);
1742 seq
= 0; /* we are already out of RCU mode */
1744 if (d_is_negative(path
.dentry
))
1748 if (flags
& WALK_PUT
)
1750 err
= should_follow_link(nd
, &path
, flags
& WALK_GET
, inode
, seq
);
1753 path_to_nameidata(&path
, nd
);
1759 path_to_nameidata(&path
, nd
);
1764 * We can do the critical dentry name comparison and hashing
1765 * operations one word at a time, but we are limited to:
1767 * - Architectures with fast unaligned word accesses. We could
1768 * do a "get_unaligned()" if this helps and is sufficiently
1771 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1772 * do not trap on the (extremely unlikely) case of a page
1773 * crossing operation.
1775 * - Furthermore, we need an efficient 64-bit compile for the
1776 * 64-bit case in order to generate the "number of bytes in
1777 * the final mask". Again, that could be replaced with a
1778 * efficient population count instruction or similar.
1780 #ifdef CONFIG_DCACHE_WORD_ACCESS
1782 #include <asm/word-at-a-time.h>
1786 static inline unsigned int fold_hash(unsigned long hash
)
1788 return hash_64(hash
, 32);
1791 #else /* 32-bit case */
1793 #define fold_hash(x) (x)
1797 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1799 unsigned long a
, mask
;
1800 unsigned long hash
= 0;
1803 a
= load_unaligned_zeropad(name
);
1804 if (len
< sizeof(unsigned long))
1808 name
+= sizeof(unsigned long);
1809 len
-= sizeof(unsigned long);
1813 mask
= bytemask_from_count(len
);
1816 return fold_hash(hash
);
1818 EXPORT_SYMBOL(full_name_hash
);
1821 * Calculate the length and hash of the path component, and
1822 * return the "hash_len" as the result.
1824 static inline u64
hash_name(const char *name
)
1826 unsigned long a
, b
, adata
, bdata
, mask
, hash
, len
;
1827 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
1830 len
= -sizeof(unsigned long);
1832 hash
= (hash
+ a
) * 9;
1833 len
+= sizeof(unsigned long);
1834 a
= load_unaligned_zeropad(name
+len
);
1835 b
= a
^ REPEAT_BYTE('/');
1836 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
1838 adata
= prep_zero_mask(a
, adata
, &constants
);
1839 bdata
= prep_zero_mask(b
, bdata
, &constants
);
1841 mask
= create_zero_mask(adata
| bdata
);
1843 hash
+= a
& zero_bytemask(mask
);
1844 len
+= find_zero(mask
);
1845 return hashlen_create(fold_hash(hash
), len
);
1850 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1852 unsigned long hash
= init_name_hash();
1854 hash
= partial_name_hash(*name
++, hash
);
1855 return end_name_hash(hash
);
1857 EXPORT_SYMBOL(full_name_hash
);
1860 * We know there's a real path component here of at least
1863 static inline u64
hash_name(const char *name
)
1865 unsigned long hash
= init_name_hash();
1866 unsigned long len
= 0, c
;
1868 c
= (unsigned char)*name
;
1871 hash
= partial_name_hash(c
, hash
);
1872 c
= (unsigned char)name
[len
];
1873 } while (c
&& c
!= '/');
1874 return hashlen_create(end_name_hash(hash
), len
);
1881 * This is the basic name resolution function, turning a pathname into
1882 * the final dentry. We expect 'base' to be positive and a directory.
1884 * Returns 0 and nd will have valid dentry and mnt on success.
1885 * Returns error and drops reference to input namei data on failure.
1887 static int link_path_walk(const char *name
, struct nameidata
*nd
)
1896 /* At this point we know we have a real path component. */
1901 err
= may_lookup(nd
);
1905 hash_len
= hash_name(name
);
1908 if (name
[0] == '.') switch (hashlen_len(hash_len
)) {
1910 if (name
[1] == '.') {
1912 nd
->flags
|= LOOKUP_JUMPED
;
1918 if (likely(type
== LAST_NORM
)) {
1919 struct dentry
*parent
= nd
->path
.dentry
;
1920 nd
->flags
&= ~LOOKUP_JUMPED
;
1921 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
1922 struct qstr
this = { { .hash_len
= hash_len
}, .name
= name
};
1923 err
= parent
->d_op
->d_hash(parent
, &this);
1926 hash_len
= this.hash_len
;
1931 nd
->last
.hash_len
= hash_len
;
1932 nd
->last
.name
= name
;
1933 nd
->last_type
= type
;
1935 name
+= hashlen_len(hash_len
);
1939 * If it wasn't NUL, we know it was '/'. Skip that
1940 * slash, and continue until no more slashes.
1944 } while (unlikely(*name
== '/'));
1945 if (unlikely(!*name
)) {
1947 /* pathname body, done */
1950 name
= nd
->stack
[nd
->depth
- 1].name
;
1951 /* trailing symlink, done */
1954 /* last component of nested symlink */
1955 err
= walk_component(nd
, WALK_GET
| WALK_PUT
);
1957 err
= walk_component(nd
, WALK_GET
);
1963 const char *s
= get_link(nd
);
1965 if (unlikely(IS_ERR(s
)))
1972 nd
->stack
[nd
->depth
- 1].name
= name
;
1977 if (unlikely(!d_can_lookup(nd
->path
.dentry
))) {
1978 if (nd
->flags
& LOOKUP_RCU
) {
1979 if (unlazy_walk(nd
, NULL
, 0))
1987 static const char *path_init(struct nameidata
*nd
, unsigned flags
)
1990 const char *s
= nd
->name
->name
;
1992 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1993 nd
->flags
= flags
| LOOKUP_JUMPED
| LOOKUP_PARENT
;
1995 nd
->total_link_count
= 0;
1996 if (flags
& LOOKUP_ROOT
) {
1997 struct dentry
*root
= nd
->root
.dentry
;
1998 struct inode
*inode
= root
->d_inode
;
2000 if (!d_can_lookup(root
))
2001 return ERR_PTR(-ENOTDIR
);
2002 retval
= inode_permission(inode
, MAY_EXEC
);
2004 return ERR_PTR(retval
);
2006 nd
->path
= nd
->root
;
2008 if (flags
& LOOKUP_RCU
) {
2010 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2011 nd
->root_seq
= nd
->seq
;
2012 nd
->m_seq
= read_seqbegin(&mount_lock
);
2014 path_get(&nd
->path
);
2019 nd
->root
.mnt
= NULL
;
2021 nd
->m_seq
= read_seqbegin(&mount_lock
);
2023 if (flags
& LOOKUP_RCU
) {
2026 nd
->seq
= nd
->root_seq
;
2029 path_get(&nd
->root
);
2031 nd
->path
= nd
->root
;
2032 } else if (nd
->dfd
== AT_FDCWD
) {
2033 if (flags
& LOOKUP_RCU
) {
2034 struct fs_struct
*fs
= current
->fs
;
2040 seq
= read_seqcount_begin(&fs
->seq
);
2042 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2043 } while (read_seqcount_retry(&fs
->seq
, seq
));
2045 get_fs_pwd(current
->fs
, &nd
->path
);
2048 /* Caller must check execute permissions on the starting path component */
2049 struct fd f
= fdget_raw(nd
->dfd
);
2050 struct dentry
*dentry
;
2053 return ERR_PTR(-EBADF
);
2055 dentry
= f
.file
->f_path
.dentry
;
2058 if (!d_can_lookup(dentry
)) {
2060 return ERR_PTR(-ENOTDIR
);
2064 nd
->path
= f
.file
->f_path
;
2065 if (flags
& LOOKUP_RCU
) {
2067 nd
->inode
= nd
->path
.dentry
->d_inode
;
2068 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2070 path_get(&nd
->path
);
2071 nd
->inode
= nd
->path
.dentry
->d_inode
;
2077 nd
->inode
= nd
->path
.dentry
->d_inode
;
2078 if (!(flags
& LOOKUP_RCU
))
2080 if (likely(!read_seqcount_retry(&nd
->path
.dentry
->d_seq
, nd
->seq
)))
2082 if (!(nd
->flags
& LOOKUP_ROOT
))
2083 nd
->root
.mnt
= NULL
;
2085 return ERR_PTR(-ECHILD
);
2088 static const char *trailing_symlink(struct nameidata
*nd
)
2091 int error
= may_follow_link(nd
);
2092 if (unlikely(error
))
2093 return ERR_PTR(error
);
2094 nd
->flags
|= LOOKUP_PARENT
;
2095 nd
->stack
[0].name
= NULL
;
2100 static inline int lookup_last(struct nameidata
*nd
)
2102 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
2103 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2105 nd
->flags
&= ~LOOKUP_PARENT
;
2106 return walk_component(nd
,
2107 nd
->flags
& LOOKUP_FOLLOW
2109 ? WALK_PUT
| WALK_GET
2114 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2115 static int path_lookupat(struct nameidata
*nd
, unsigned flags
, struct path
*path
)
2117 const char *s
= path_init(nd
, flags
);
2122 while (!(err
= link_path_walk(s
, nd
))
2123 && ((err
= lookup_last(nd
)) > 0)) {
2124 s
= trailing_symlink(nd
);
2131 err
= complete_walk(nd
);
2133 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
)
2134 if (!d_can_lookup(nd
->path
.dentry
))
2138 nd
->path
.mnt
= NULL
;
2139 nd
->path
.dentry
= NULL
;
2145 static int filename_lookup(int dfd
, struct filename
*name
, unsigned flags
,
2146 struct path
*path
, struct path
*root
)
2149 struct nameidata nd
;
2151 return PTR_ERR(name
);
2152 if (unlikely(root
)) {
2154 flags
|= LOOKUP_ROOT
;
2156 set_nameidata(&nd
, dfd
, name
);
2157 retval
= path_lookupat(&nd
, flags
| LOOKUP_RCU
, path
);
2158 if (unlikely(retval
== -ECHILD
))
2159 retval
= path_lookupat(&nd
, flags
, path
);
2160 if (unlikely(retval
== -ESTALE
))
2161 retval
= path_lookupat(&nd
, flags
| LOOKUP_REVAL
, path
);
2163 if (likely(!retval
))
2164 audit_inode(name
, path
->dentry
, flags
& LOOKUP_PARENT
);
2165 restore_nameidata();
2170 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2171 static int path_parentat(struct nameidata
*nd
, unsigned flags
,
2172 struct path
*parent
)
2174 const char *s
= path_init(nd
, flags
);
2178 err
= link_path_walk(s
, nd
);
2180 err
= complete_walk(nd
);
2183 nd
->path
.mnt
= NULL
;
2184 nd
->path
.dentry
= NULL
;
2190 static struct filename
*filename_parentat(int dfd
, struct filename
*name
,
2191 unsigned int flags
, struct path
*parent
,
2192 struct qstr
*last
, int *type
)
2195 struct nameidata nd
;
2199 set_nameidata(&nd
, dfd
, name
);
2200 retval
= path_parentat(&nd
, flags
| LOOKUP_RCU
, parent
);
2201 if (unlikely(retval
== -ECHILD
))
2202 retval
= path_parentat(&nd
, flags
, parent
);
2203 if (unlikely(retval
== -ESTALE
))
2204 retval
= path_parentat(&nd
, flags
| LOOKUP_REVAL
, parent
);
2205 if (likely(!retval
)) {
2207 *type
= nd
.last_type
;
2208 audit_inode(name
, parent
->dentry
, LOOKUP_PARENT
);
2211 name
= ERR_PTR(retval
);
2213 restore_nameidata();
2217 /* does lookup, returns the object with parent locked */
2218 struct dentry
*kern_path_locked(const char *name
, struct path
*path
)
2220 struct filename
*filename
;
2225 filename
= filename_parentat(AT_FDCWD
, getname_kernel(name
), 0, path
,
2227 if (IS_ERR(filename
))
2228 return ERR_CAST(filename
);
2229 if (unlikely(type
!= LAST_NORM
)) {
2232 return ERR_PTR(-EINVAL
);
2234 mutex_lock_nested(&path
->dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2235 d
= __lookup_hash(&last
, path
->dentry
, 0);
2237 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
2244 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
2246 return filename_lookup(AT_FDCWD
, getname_kernel(name
),
2249 EXPORT_SYMBOL(kern_path
);
2252 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2253 * @dentry: pointer to dentry of the base directory
2254 * @mnt: pointer to vfs mount of the base directory
2255 * @name: pointer to file name
2256 * @flags: lookup flags
2257 * @path: pointer to struct path to fill
2259 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
2260 const char *name
, unsigned int flags
,
2263 struct path root
= {.mnt
= mnt
, .dentry
= dentry
};
2264 /* the first argument of filename_lookup() is ignored with root */
2265 return filename_lookup(AT_FDCWD
, getname_kernel(name
),
2266 flags
, path
, &root
);
2268 EXPORT_SYMBOL(vfs_path_lookup
);
2271 * lookup_one_len - filesystem helper to lookup single pathname component
2272 * @name: pathname component to lookup
2273 * @base: base directory to lookup from
2274 * @len: maximum length @len should be interpreted to
2276 * Note that this routine is purely a helper for filesystem usage and should
2277 * not be called by generic code.
2279 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2285 WARN_ON_ONCE(!mutex_is_locked(&base
->d_inode
->i_mutex
));
2289 this.hash
= full_name_hash(name
, len
);
2291 return ERR_PTR(-EACCES
);
2293 if (unlikely(name
[0] == '.')) {
2294 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2295 return ERR_PTR(-EACCES
);
2299 c
= *(const unsigned char *)name
++;
2300 if (c
== '/' || c
== '\0')
2301 return ERR_PTR(-EACCES
);
2304 * See if the low-level filesystem might want
2305 * to use its own hash..
2307 if (base
->d_flags
& DCACHE_OP_HASH
) {
2308 int err
= base
->d_op
->d_hash(base
, &this);
2310 return ERR_PTR(err
);
2313 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
2315 return ERR_PTR(err
);
2317 return __lookup_hash(&this, base
, 0);
2319 EXPORT_SYMBOL(lookup_one_len
);
2321 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
2322 struct path
*path
, int *empty
)
2324 return filename_lookup(dfd
, getname_flags(name
, flags
, empty
),
2327 EXPORT_SYMBOL(user_path_at_empty
);
2330 * NB: most callers don't do anything directly with the reference to the
2331 * to struct filename, but the nd->last pointer points into the name string
2332 * allocated by getname. So we must hold the reference to it until all
2333 * path-walking is complete.
2335 static inline struct filename
*
2336 user_path_parent(int dfd
, const char __user
*path
,
2337 struct path
*parent
,
2342 /* only LOOKUP_REVAL is allowed in extra flags */
2343 return filename_parentat(dfd
, getname(path
), flags
& LOOKUP_REVAL
,
2344 parent
, last
, type
);
2348 * mountpoint_last - look up last component for umount
2349 * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
2350 * @path: pointer to container for result
2352 * This is a special lookup_last function just for umount. In this case, we
2353 * need to resolve the path without doing any revalidation.
2355 * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
2356 * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
2357 * in almost all cases, this lookup will be served out of the dcache. The only
2358 * cases where it won't are if nd->last refers to a symlink or the path is
2359 * bogus and it doesn't exist.
2362 * -error: if there was an error during lookup. This includes -ENOENT if the
2363 * lookup found a negative dentry. The nd->path reference will also be
2366 * 0: if we successfully resolved nd->path and found it to not to be a
2367 * symlink that needs to be followed. "path" will also be populated.
2368 * The nd->path reference will also be put.
2370 * 1: if we successfully resolved nd->last and found it to be a symlink
2371 * that needs to be followed. "path" will be populated with the path
2372 * to the link, and nd->path will *not* be put.
2375 mountpoint_last(struct nameidata
*nd
, struct path
*path
)
2378 struct dentry
*dentry
;
2379 struct dentry
*dir
= nd
->path
.dentry
;
2381 /* If we're in rcuwalk, drop out of it to handle last component */
2382 if (nd
->flags
& LOOKUP_RCU
) {
2383 if (unlazy_walk(nd
, NULL
, 0))
2387 nd
->flags
&= ~LOOKUP_PARENT
;
2389 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
2390 error
= handle_dots(nd
, nd
->last_type
);
2393 dentry
= dget(nd
->path
.dentry
);
2397 mutex_lock(&dir
->d_inode
->i_mutex
);
2398 dentry
= d_lookup(dir
, &nd
->last
);
2401 * No cached dentry. Mounted dentries are pinned in the cache,
2402 * so that means that this dentry is probably a symlink or the
2403 * path doesn't actually point to a mounted dentry.
2405 dentry
= d_alloc(dir
, &nd
->last
);
2407 mutex_unlock(&dir
->d_inode
->i_mutex
);
2410 dentry
= lookup_real(dir
->d_inode
, dentry
, nd
->flags
);
2411 if (IS_ERR(dentry
)) {
2412 mutex_unlock(&dir
->d_inode
->i_mutex
);
2413 return PTR_ERR(dentry
);
2416 mutex_unlock(&dir
->d_inode
->i_mutex
);
2419 if (d_is_negative(dentry
)) {
2425 path
->dentry
= dentry
;
2426 path
->mnt
= nd
->path
.mnt
;
2427 error
= should_follow_link(nd
, path
, nd
->flags
& LOOKUP_FOLLOW
,
2428 d_backing_inode(dentry
), 0);
2429 if (unlikely(error
))
2437 * path_mountpoint - look up a path to be umounted
2438 * @nd: lookup context
2439 * @flags: lookup flags
2440 * @path: pointer to container for result
2442 * Look up the given name, but don't attempt to revalidate the last component.
2443 * Returns 0 and "path" will be valid on success; Returns error otherwise.
2446 path_mountpoint(struct nameidata
*nd
, unsigned flags
, struct path
*path
)
2448 const char *s
= path_init(nd
, flags
);
2452 while (!(err
= link_path_walk(s
, nd
)) &&
2453 (err
= mountpoint_last(nd
, path
)) > 0) {
2454 s
= trailing_symlink(nd
);
2465 filename_mountpoint(int dfd
, struct filename
*name
, struct path
*path
,
2468 struct nameidata nd
;
2471 return PTR_ERR(name
);
2472 set_nameidata(&nd
, dfd
, name
);
2473 error
= path_mountpoint(&nd
, flags
| LOOKUP_RCU
, path
);
2474 if (unlikely(error
== -ECHILD
))
2475 error
= path_mountpoint(&nd
, flags
, path
);
2476 if (unlikely(error
== -ESTALE
))
2477 error
= path_mountpoint(&nd
, flags
| LOOKUP_REVAL
, path
);
2479 audit_inode(name
, path
->dentry
, 0);
2480 restore_nameidata();
2486 * user_path_mountpoint_at - lookup a path from userland in order to umount it
2487 * @dfd: directory file descriptor
2488 * @name: pathname from userland
2489 * @flags: lookup flags
2490 * @path: pointer to container to hold result
2492 * A umount is a special case for path walking. We're not actually interested
2493 * in the inode in this situation, and ESTALE errors can be a problem. We
2494 * simply want track down the dentry and vfsmount attached at the mountpoint
2495 * and avoid revalidating the last component.
2497 * Returns 0 and populates "path" on success.
2500 user_path_mountpoint_at(int dfd
, const char __user
*name
, unsigned int flags
,
2503 return filename_mountpoint(dfd
, getname(name
), path
, flags
);
2507 kern_path_mountpoint(int dfd
, const char *name
, struct path
*path
,
2510 return filename_mountpoint(dfd
, getname_kernel(name
), path
, flags
);
2512 EXPORT_SYMBOL(kern_path_mountpoint
);
2514 int __check_sticky(struct inode
*dir
, struct inode
*inode
)
2516 kuid_t fsuid
= current_fsuid();
2518 if (uid_eq(inode
->i_uid
, fsuid
))
2520 if (uid_eq(dir
->i_uid
, fsuid
))
2522 return !capable_wrt_inode_uidgid(inode
, CAP_FOWNER
);
2524 EXPORT_SYMBOL(__check_sticky
);
2527 * Check whether we can remove a link victim from directory dir, check
2528 * whether the type of victim is right.
2529 * 1. We can't do it if dir is read-only (done in permission())
2530 * 2. We should have write and exec permissions on dir
2531 * 3. We can't remove anything from append-only dir
2532 * 4. We can't do anything with immutable dir (done in permission())
2533 * 5. If the sticky bit on dir is set we should either
2534 * a. be owner of dir, or
2535 * b. be owner of victim, or
2536 * c. have CAP_FOWNER capability
2537 * 6. If the victim is append-only or immutable we can't do antyhing with
2538 * links pointing to it.
2539 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2540 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2541 * 9. We can't remove a root or mountpoint.
2542 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
2543 * nfs_async_unlink().
2545 static int may_delete(struct inode
*dir
, struct dentry
*victim
, bool isdir
)
2547 struct inode
*inode
= d_backing_inode(victim
);
2550 if (d_is_negative(victim
))
2554 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
2555 audit_inode_child(dir
, victim
, AUDIT_TYPE_CHILD_DELETE
);
2557 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2563 if (check_sticky(dir
, inode
) || IS_APPEND(inode
) ||
2564 IS_IMMUTABLE(inode
) || IS_SWAPFILE(inode
))
2567 if (!d_is_dir(victim
))
2569 if (IS_ROOT(victim
))
2571 } else if (d_is_dir(victim
))
2573 if (IS_DEADDIR(dir
))
2575 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2580 /* Check whether we can create an object with dentry child in directory
2582 * 1. We can't do it if child already exists (open has special treatment for
2583 * this case, but since we are inlined it's OK)
2584 * 2. We can't do it if dir is read-only (done in permission())
2585 * 3. We should have write and exec permissions on dir
2586 * 4. We can't do it if dir is immutable (done in permission())
2588 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
2590 audit_inode_child(dir
, child
, AUDIT_TYPE_CHILD_CREATE
);
2593 if (IS_DEADDIR(dir
))
2595 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2599 * p1 and p2 should be directories on the same fs.
2601 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2606 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2610 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2612 p
= d_ancestor(p2
, p1
);
2614 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2615 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2619 p
= d_ancestor(p1
, p2
);
2621 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2622 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2626 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2627 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT2
);
2630 EXPORT_SYMBOL(lock_rename
);
2632 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
2634 mutex_unlock(&p1
->d_inode
->i_mutex
);
2636 mutex_unlock(&p2
->d_inode
->i_mutex
);
2637 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2640 EXPORT_SYMBOL(unlock_rename
);
2642 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
2645 int error
= may_create(dir
, dentry
);
2649 if (!dir
->i_op
->create
)
2650 return -EACCES
; /* shouldn't it be ENOSYS? */
2653 error
= security_inode_create(dir
, dentry
, mode
);
2656 error
= dir
->i_op
->create(dir
, dentry
, mode
, want_excl
);
2658 fsnotify_create(dir
, dentry
);
2661 EXPORT_SYMBOL(vfs_create
);
2663 static int may_open(struct path
*path
, int acc_mode
, int flag
)
2665 struct dentry
*dentry
= path
->dentry
;
2666 struct inode
*inode
= dentry
->d_inode
;
2676 switch (inode
->i_mode
& S_IFMT
) {
2680 if (acc_mode
& MAY_WRITE
)
2685 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
2694 error
= inode_permission(inode
, acc_mode
);
2699 * An append-only file must be opened in append mode for writing.
2701 if (IS_APPEND(inode
)) {
2702 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
2708 /* O_NOATIME can only be set by the owner or superuser */
2709 if (flag
& O_NOATIME
&& !inode_owner_or_capable(inode
))
2715 static int handle_truncate(struct file
*filp
)
2717 struct path
*path
= &filp
->f_path
;
2718 struct inode
*inode
= path
->dentry
->d_inode
;
2719 int error
= get_write_access(inode
);
2723 * Refuse to truncate files with mandatory locks held on them.
2725 error
= locks_verify_locked(filp
);
2727 error
= security_path_truncate(path
);
2729 error
= do_truncate(path
->dentry
, 0,
2730 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
2733 put_write_access(inode
);
2737 static inline int open_to_namei_flags(int flag
)
2739 if ((flag
& O_ACCMODE
) == 3)
2744 static int may_o_create(struct path
*dir
, struct dentry
*dentry
, umode_t mode
)
2746 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
2750 error
= inode_permission(dir
->dentry
->d_inode
, MAY_WRITE
| MAY_EXEC
);
2754 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
2758 * Attempt to atomically look up, create and open a file from a negative
2761 * Returns 0 if successful. The file will have been created and attached to
2762 * @file by the filesystem calling finish_open().
2764 * Returns 1 if the file was looked up only or didn't need creating. The
2765 * caller will need to perform the open themselves. @path will have been
2766 * updated to point to the new dentry. This may be negative.
2768 * Returns an error code otherwise.
2770 static int atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
2771 struct path
*path
, struct file
*file
,
2772 const struct open_flags
*op
,
2773 bool got_write
, bool need_lookup
,
2776 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
2777 unsigned open_flag
= open_to_namei_flags(op
->open_flag
);
2781 int create_error
= 0;
2782 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
2785 BUG_ON(dentry
->d_inode
);
2787 /* Don't create child dentry for a dead directory. */
2788 if (unlikely(IS_DEADDIR(dir
))) {
2794 if ((open_flag
& O_CREAT
) && !IS_POSIXACL(dir
))
2795 mode
&= ~current_umask();
2797 excl
= (open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
);
2799 open_flag
&= ~O_TRUNC
;
2802 * Checking write permission is tricky, bacuse we don't know if we are
2803 * going to actually need it: O_CREAT opens should work as long as the
2804 * file exists. But checking existence breaks atomicity. The trick is
2805 * to check access and if not granted clear O_CREAT from the flags.
2807 * Another problem is returing the "right" error value (e.g. for an
2808 * O_EXCL open we want to return EEXIST not EROFS).
2810 if (((open_flag
& (O_CREAT
| O_TRUNC
)) ||
2811 (open_flag
& O_ACCMODE
) != O_RDONLY
) && unlikely(!got_write
)) {
2812 if (!(open_flag
& O_CREAT
)) {
2814 * No O_CREATE -> atomicity not a requirement -> fall
2815 * back to lookup + open
2818 } else if (open_flag
& (O_EXCL
| O_TRUNC
)) {
2819 /* Fall back and fail with the right error */
2820 create_error
= -EROFS
;
2823 /* No side effects, safe to clear O_CREAT */
2824 create_error
= -EROFS
;
2825 open_flag
&= ~O_CREAT
;
2829 if (open_flag
& O_CREAT
) {
2830 error
= may_o_create(&nd
->path
, dentry
, mode
);
2832 create_error
= error
;
2833 if (open_flag
& O_EXCL
)
2835 open_flag
&= ~O_CREAT
;
2839 if (nd
->flags
& LOOKUP_DIRECTORY
)
2840 open_flag
|= O_DIRECTORY
;
2842 file
->f_path
.dentry
= DENTRY_NOT_SET
;
2843 file
->f_path
.mnt
= nd
->path
.mnt
;
2844 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
, open_flag
, mode
,
2847 if (create_error
&& error
== -ENOENT
)
2848 error
= create_error
;
2852 if (error
) { /* returned 1, that is */
2853 if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
2857 if (file
->f_path
.dentry
) {
2859 dentry
= file
->f_path
.dentry
;
2861 if (*opened
& FILE_CREATED
)
2862 fsnotify_create(dir
, dentry
);
2863 if (!dentry
->d_inode
) {
2864 WARN_ON(*opened
& FILE_CREATED
);
2866 error
= create_error
;
2870 if (excl
&& !(*opened
& FILE_CREATED
)) {
2879 * We didn't have the inode before the open, so check open permission
2882 acc_mode
= op
->acc_mode
;
2883 if (*opened
& FILE_CREATED
) {
2884 WARN_ON(!(open_flag
& O_CREAT
));
2885 fsnotify_create(dir
, dentry
);
2886 acc_mode
= MAY_OPEN
;
2888 error
= may_open(&file
->f_path
, acc_mode
, open_flag
);
2898 dentry
= lookup_real(dir
, dentry
, nd
->flags
);
2900 return PTR_ERR(dentry
);
2903 int open_flag
= op
->open_flag
;
2905 error
= create_error
;
2906 if ((open_flag
& O_EXCL
)) {
2907 if (!dentry
->d_inode
)
2909 } else if (!dentry
->d_inode
) {
2911 } else if ((open_flag
& O_TRUNC
) &&
2915 /* will fail later, go on to get the right error */
2919 path
->dentry
= dentry
;
2920 path
->mnt
= nd
->path
.mnt
;
2925 * Look up and maybe create and open the last component.
2927 * Must be called with i_mutex held on parent.
2929 * Returns 0 if the file was successfully atomically created (if necessary) and
2930 * opened. In this case the file will be returned attached to @file.
2932 * Returns 1 if the file was not completely opened at this time, though lookups
2933 * and creations will have been performed and the dentry returned in @path will
2934 * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
2935 * specified then a negative dentry may be returned.
2937 * An error code is returned otherwise.
2939 * FILE_CREATE will be set in @*opened if the dentry was created and will be
2940 * cleared otherwise prior to returning.
2942 static int lookup_open(struct nameidata
*nd
, struct path
*path
,
2944 const struct open_flags
*op
,
2945 bool got_write
, int *opened
)
2947 struct dentry
*dir
= nd
->path
.dentry
;
2948 struct inode
*dir_inode
= dir
->d_inode
;
2949 struct dentry
*dentry
;
2953 *opened
&= ~FILE_CREATED
;
2954 dentry
= lookup_dcache(&nd
->last
, dir
, nd
->flags
, &need_lookup
);
2956 return PTR_ERR(dentry
);
2958 /* Cached positive dentry: will open in f_op->open */
2959 if (!need_lookup
&& dentry
->d_inode
)
2962 if ((nd
->flags
& LOOKUP_OPEN
) && dir_inode
->i_op
->atomic_open
) {
2963 return atomic_open(nd
, dentry
, path
, file
, op
, got_write
,
2964 need_lookup
, opened
);
2968 BUG_ON(dentry
->d_inode
);
2970 dentry
= lookup_real(dir_inode
, dentry
, nd
->flags
);
2972 return PTR_ERR(dentry
);
2975 /* Negative dentry, just create the file */
2976 if (!dentry
->d_inode
&& (op
->open_flag
& O_CREAT
)) {
2977 umode_t mode
= op
->mode
;
2978 if (!IS_POSIXACL(dir
->d_inode
))
2979 mode
&= ~current_umask();
2981 * This write is needed to ensure that a
2982 * rw->ro transition does not occur between
2983 * the time when the file is created and when
2984 * a permanent write count is taken through
2985 * the 'struct file' in finish_open().
2991 *opened
|= FILE_CREATED
;
2992 error
= security_path_mknod(&nd
->path
, dentry
, mode
, 0);
2995 error
= vfs_create(dir
->d_inode
, dentry
, mode
,
2996 nd
->flags
& LOOKUP_EXCL
);
3001 path
->dentry
= dentry
;
3002 path
->mnt
= nd
->path
.mnt
;
3011 * Handle the last step of open()
3013 static int do_last(struct nameidata
*nd
,
3014 struct file
*file
, const struct open_flags
*op
,
3017 struct dentry
*dir
= nd
->path
.dentry
;
3018 int open_flag
= op
->open_flag
;
3019 bool will_truncate
= (open_flag
& O_TRUNC
) != 0;
3020 bool got_write
= false;
3021 int acc_mode
= op
->acc_mode
;
3023 struct inode
*inode
;
3024 struct path save_parent
= { .dentry
= NULL
, .mnt
= NULL
};
3026 bool retried
= false;
3029 nd
->flags
&= ~LOOKUP_PARENT
;
3030 nd
->flags
|= op
->intent
;
3032 if (nd
->last_type
!= LAST_NORM
) {
3033 error
= handle_dots(nd
, nd
->last_type
);
3034 if (unlikely(error
))
3039 if (!(open_flag
& O_CREAT
)) {
3040 if (nd
->last
.name
[nd
->last
.len
])
3041 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
3042 /* we _can_ be in RCU mode here */
3043 error
= lookup_fast(nd
, &path
, &inode
, &seq
);
3050 BUG_ON(nd
->inode
!= dir
->d_inode
);
3052 /* create side of things */
3054 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
3055 * has been cleared when we got to the last component we are
3058 error
= complete_walk(nd
);
3062 audit_inode(nd
->name
, dir
, LOOKUP_PARENT
);
3063 /* trailing slashes? */
3064 if (unlikely(nd
->last
.name
[nd
->last
.len
]))
3069 if (op
->open_flag
& (O_CREAT
| O_TRUNC
| O_WRONLY
| O_RDWR
)) {
3070 error
= mnt_want_write(nd
->path
.mnt
);
3074 * do _not_ fail yet - we might not need that or fail with
3075 * a different error; let lookup_open() decide; we'll be
3076 * dropping this one anyway.
3079 mutex_lock(&dir
->d_inode
->i_mutex
);
3080 error
= lookup_open(nd
, &path
, file
, op
, got_write
, opened
);
3081 mutex_unlock(&dir
->d_inode
->i_mutex
);
3087 if ((*opened
& FILE_CREATED
) ||
3088 !S_ISREG(file_inode(file
)->i_mode
))
3089 will_truncate
= false;
3091 audit_inode(nd
->name
, file
->f_path
.dentry
, 0);
3095 if (*opened
& FILE_CREATED
) {
3096 /* Don't check for write permission, don't truncate */
3097 open_flag
&= ~O_TRUNC
;
3098 will_truncate
= false;
3099 acc_mode
= MAY_OPEN
;
3100 path_to_nameidata(&path
, nd
);
3101 goto finish_open_created
;
3105 * create/update audit record if it already exists.
3107 if (d_is_positive(path
.dentry
))
3108 audit_inode(nd
->name
, path
.dentry
, 0);
3111 * If atomic_open() acquired write access it is dropped now due to
3112 * possible mount and symlink following (this might be optimized away if
3116 mnt_drop_write(nd
->path
.mnt
);
3120 if (unlikely((open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
))) {
3121 path_to_nameidata(&path
, nd
);
3125 error
= follow_managed(&path
, nd
);
3126 if (unlikely(error
< 0))
3129 BUG_ON(nd
->flags
& LOOKUP_RCU
);
3130 inode
= d_backing_inode(path
.dentry
);
3131 seq
= 0; /* out of RCU mode, so the value doesn't matter */
3132 if (unlikely(d_is_negative(path
.dentry
))) {
3133 path_to_nameidata(&path
, nd
);
3139 error
= should_follow_link(nd
, &path
, nd
->flags
& LOOKUP_FOLLOW
,
3141 if (unlikely(error
))
3144 if (unlikely(d_is_symlink(path
.dentry
)) && !(open_flag
& O_PATH
)) {
3145 path_to_nameidata(&path
, nd
);
3149 if ((nd
->flags
& LOOKUP_RCU
) || nd
->path
.mnt
!= path
.mnt
) {
3150 path_to_nameidata(&path
, nd
);
3152 save_parent
.dentry
= nd
->path
.dentry
;
3153 save_parent
.mnt
= mntget(path
.mnt
);
3154 nd
->path
.dentry
= path
.dentry
;
3159 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
3161 error
= complete_walk(nd
);
3163 path_put(&save_parent
);
3166 audit_inode(nd
->name
, nd
->path
.dentry
, 0);
3168 if ((open_flag
& O_CREAT
) && d_is_dir(nd
->path
.dentry
))
3171 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !d_can_lookup(nd
->path
.dentry
))
3173 if (!d_is_reg(nd
->path
.dentry
))
3174 will_truncate
= false;
3176 if (will_truncate
) {
3177 error
= mnt_want_write(nd
->path
.mnt
);
3182 finish_open_created
:
3183 error
= may_open(&nd
->path
, acc_mode
, open_flag
);
3187 BUG_ON(*opened
& FILE_OPENED
); /* once it's opened, it's opened */
3188 error
= vfs_open(&nd
->path
, file
, current_cred());
3190 *opened
|= FILE_OPENED
;
3192 if (error
== -EOPENSTALE
)
3197 error
= open_check_o_direct(file
);
3200 error
= ima_file_check(file
, op
->acc_mode
, *opened
);
3204 if (will_truncate
) {
3205 error
= handle_truncate(file
);
3211 mnt_drop_write(nd
->path
.mnt
);
3212 path_put(&save_parent
);
3220 /* If no saved parent or already retried then can't retry */
3221 if (!save_parent
.dentry
|| retried
)
3224 BUG_ON(save_parent
.dentry
!= dir
);
3225 path_put(&nd
->path
);
3226 nd
->path
= save_parent
;
3227 nd
->inode
= dir
->d_inode
;
3228 save_parent
.mnt
= NULL
;
3229 save_parent
.dentry
= NULL
;
3231 mnt_drop_write(nd
->path
.mnt
);
3238 static int do_tmpfile(struct nameidata
*nd
, unsigned flags
,
3239 const struct open_flags
*op
,
3240 struct file
*file
, int *opened
)
3242 static const struct qstr name
= QSTR_INIT("/", 1);
3243 struct dentry
*child
;
3246 int error
= path_lookupat(nd
, flags
| LOOKUP_DIRECTORY
, &path
);
3247 if (unlikely(error
))
3249 error
= mnt_want_write(path
.mnt
);
3250 if (unlikely(error
))
3252 dir
= path
.dentry
->d_inode
;
3253 /* we want directory to be writable */
3254 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
3257 if (!dir
->i_op
->tmpfile
) {
3258 error
= -EOPNOTSUPP
;
3261 child
= d_alloc(path
.dentry
, &name
);
3262 if (unlikely(!child
)) {
3267 path
.dentry
= child
;
3268 error
= dir
->i_op
->tmpfile(dir
, child
, op
->mode
);
3271 audit_inode(nd
->name
, child
, 0);
3272 /* Don't check for other permissions, the inode was just created */
3273 error
= may_open(&path
, MAY_OPEN
, op
->open_flag
);
3276 file
->f_path
.mnt
= path
.mnt
;
3277 error
= finish_open(file
, child
, NULL
, opened
);
3280 error
= open_check_o_direct(file
);
3283 } else if (!(op
->open_flag
& O_EXCL
)) {
3284 struct inode
*inode
= file_inode(file
);
3285 spin_lock(&inode
->i_lock
);
3286 inode
->i_state
|= I_LINKABLE
;
3287 spin_unlock(&inode
->i_lock
);
3290 mnt_drop_write(path
.mnt
);
3296 static struct file
*path_openat(struct nameidata
*nd
,
3297 const struct open_flags
*op
, unsigned flags
)
3304 file
= get_empty_filp();
3308 file
->f_flags
= op
->open_flag
;
3310 if (unlikely(file
->f_flags
& __O_TMPFILE
)) {
3311 error
= do_tmpfile(nd
, flags
, op
, file
, &opened
);
3315 s
= path_init(nd
, flags
);
3320 while (!(error
= link_path_walk(s
, nd
)) &&
3321 (error
= do_last(nd
, file
, op
, &opened
)) > 0) {
3322 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
3323 s
= trailing_symlink(nd
);
3331 if (!(opened
& FILE_OPENED
)) {
3335 if (unlikely(error
)) {
3336 if (error
== -EOPENSTALE
) {
3337 if (flags
& LOOKUP_RCU
)
3342 file
= ERR_PTR(error
);
3347 struct file
*do_filp_open(int dfd
, struct filename
*pathname
,
3348 const struct open_flags
*op
)
3350 struct nameidata nd
;
3351 int flags
= op
->lookup_flags
;
3354 set_nameidata(&nd
, dfd
, pathname
);
3355 filp
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3356 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
3357 filp
= path_openat(&nd
, op
, flags
);
3358 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
3359 filp
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3360 restore_nameidata();
3364 struct file
*do_file_open_root(struct dentry
*dentry
, struct vfsmount
*mnt
,
3365 const char *name
, const struct open_flags
*op
)
3367 struct nameidata nd
;
3369 struct filename
*filename
;
3370 int flags
= op
->lookup_flags
| LOOKUP_ROOT
;
3373 nd
.root
.dentry
= dentry
;
3375 if (d_is_symlink(dentry
) && op
->intent
& LOOKUP_OPEN
)
3376 return ERR_PTR(-ELOOP
);
3378 filename
= getname_kernel(name
);
3379 if (unlikely(IS_ERR(filename
)))
3380 return ERR_CAST(filename
);
3382 set_nameidata(&nd
, -1, filename
);
3383 file
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3384 if (unlikely(file
== ERR_PTR(-ECHILD
)))
3385 file
= path_openat(&nd
, op
, flags
);
3386 if (unlikely(file
== ERR_PTR(-ESTALE
)))
3387 file
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3388 restore_nameidata();
3393 static struct dentry
*filename_create(int dfd
, struct filename
*name
,
3394 struct path
*path
, unsigned int lookup_flags
)
3396 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
3401 bool is_dir
= (lookup_flags
& LOOKUP_DIRECTORY
);
3404 * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
3405 * other flags passed in are ignored!
3407 lookup_flags
&= LOOKUP_REVAL
;
3409 name
= filename_parentat(dfd
, name
, lookup_flags
, path
, &last
, &type
);
3411 return ERR_CAST(name
);
3414 * Yucky last component or no last component at all?
3415 * (foo/., foo/.., /////)
3417 if (unlikely(type
!= LAST_NORM
))
3420 /* don't fail immediately if it's r/o, at least try to report other errors */
3421 err2
= mnt_want_write(path
->mnt
);
3423 * Do the final lookup.
3425 lookup_flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
3426 mutex_lock_nested(&path
->dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3427 dentry
= __lookup_hash(&last
, path
->dentry
, lookup_flags
);
3432 if (d_is_positive(dentry
))
3436 * Special case - lookup gave negative, but... we had foo/bar/
3437 * From the vfs_mknod() POV we just have a negative dentry -
3438 * all is fine. Let's be bastards - you had / on the end, you've
3439 * been asking for (non-existent) directory. -ENOENT for you.
3441 if (unlikely(!is_dir
&& last
.name
[last
.len
])) {
3445 if (unlikely(err2
)) {
3453 dentry
= ERR_PTR(error
);
3455 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
3457 mnt_drop_write(path
->mnt
);
3464 struct dentry
*kern_path_create(int dfd
, const char *pathname
,
3465 struct path
*path
, unsigned int lookup_flags
)
3467 return filename_create(dfd
, getname_kernel(pathname
),
3468 path
, lookup_flags
);
3470 EXPORT_SYMBOL(kern_path_create
);
3472 void done_path_create(struct path
*path
, struct dentry
*dentry
)
3475 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
3476 mnt_drop_write(path
->mnt
);
3479 EXPORT_SYMBOL(done_path_create
);
3481 inline struct dentry
*user_path_create(int dfd
, const char __user
*pathname
,
3482 struct path
*path
, unsigned int lookup_flags
)
3484 return filename_create(dfd
, getname(pathname
), path
, lookup_flags
);
3486 EXPORT_SYMBOL(user_path_create
);
3488 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3490 int error
= may_create(dir
, dentry
);
3495 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
3498 if (!dir
->i_op
->mknod
)
3501 error
= devcgroup_inode_mknod(mode
, dev
);
3505 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
3509 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
3511 fsnotify_create(dir
, dentry
);
3514 EXPORT_SYMBOL(vfs_mknod
);
3516 static int may_mknod(umode_t mode
)
3518 switch (mode
& S_IFMT
) {
3524 case 0: /* zero mode translates to S_IFREG */
3533 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
3536 struct dentry
*dentry
;
3539 unsigned int lookup_flags
= 0;
3541 error
= may_mknod(mode
);
3545 dentry
= user_path_create(dfd
, filename
, &path
, lookup_flags
);
3547 return PTR_ERR(dentry
);
3549 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3550 mode
&= ~current_umask();
3551 error
= security_path_mknod(&path
, dentry
, mode
, dev
);
3554 switch (mode
& S_IFMT
) {
3555 case 0: case S_IFREG
:
3556 error
= vfs_create(path
.dentry
->d_inode
,dentry
,mode
,true);
3558 case S_IFCHR
: case S_IFBLK
:
3559 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,
3560 new_decode_dev(dev
));
3562 case S_IFIFO
: case S_IFSOCK
:
3563 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,0);
3567 done_path_create(&path
, dentry
);
3568 if (retry_estale(error
, lookup_flags
)) {
3569 lookup_flags
|= LOOKUP_REVAL
;
3575 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
3577 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
3580 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
3582 int error
= may_create(dir
, dentry
);
3583 unsigned max_links
= dir
->i_sb
->s_max_links
;
3588 if (!dir
->i_op
->mkdir
)
3591 mode
&= (S_IRWXUGO
|S_ISVTX
);
3592 error
= security_inode_mkdir(dir
, dentry
, mode
);
3596 if (max_links
&& dir
->i_nlink
>= max_links
)
3599 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
3601 fsnotify_mkdir(dir
, dentry
);
3604 EXPORT_SYMBOL(vfs_mkdir
);
3606 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, umode_t
, mode
)
3608 struct dentry
*dentry
;
3611 unsigned int lookup_flags
= LOOKUP_DIRECTORY
;
3614 dentry
= user_path_create(dfd
, pathname
, &path
, lookup_flags
);
3616 return PTR_ERR(dentry
);
3618 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3619 mode
&= ~current_umask();
3620 error
= security_path_mkdir(&path
, dentry
, mode
);
3622 error
= vfs_mkdir(path
.dentry
->d_inode
, dentry
, mode
);
3623 done_path_create(&path
, dentry
);
3624 if (retry_estale(error
, lookup_flags
)) {
3625 lookup_flags
|= LOOKUP_REVAL
;
3631 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, umode_t
, mode
)
3633 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
3637 * The dentry_unhash() helper will try to drop the dentry early: we
3638 * should have a usage count of 1 if we're the only user of this
3639 * dentry, and if that is true (possibly after pruning the dcache),
3640 * then we drop the dentry now.
3642 * A low-level filesystem can, if it choses, legally
3645 * if (!d_unhashed(dentry))
3648 * if it cannot handle the case of removing a directory
3649 * that is still in use by something else..
3651 void dentry_unhash(struct dentry
*dentry
)
3653 shrink_dcache_parent(dentry
);
3654 spin_lock(&dentry
->d_lock
);
3655 if (dentry
->d_lockref
.count
== 1)
3657 spin_unlock(&dentry
->d_lock
);
3659 EXPORT_SYMBOL(dentry_unhash
);
3661 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
3663 int error
= may_delete(dir
, dentry
, 1);
3668 if (!dir
->i_op
->rmdir
)
3672 mutex_lock(&dentry
->d_inode
->i_mutex
);
3675 if (is_local_mountpoint(dentry
))
3678 error
= security_inode_rmdir(dir
, dentry
);
3682 shrink_dcache_parent(dentry
);
3683 error
= dir
->i_op
->rmdir(dir
, dentry
);
3687 dentry
->d_inode
->i_flags
|= S_DEAD
;
3689 detach_mounts(dentry
);
3692 mutex_unlock(&dentry
->d_inode
->i_mutex
);
3698 EXPORT_SYMBOL(vfs_rmdir
);
3700 static long do_rmdir(int dfd
, const char __user
*pathname
)
3703 struct filename
*name
;
3704 struct dentry
*dentry
;
3708 unsigned int lookup_flags
= 0;
3710 name
= user_path_parent(dfd
, pathname
,
3711 &path
, &last
, &type
, lookup_flags
);
3713 return PTR_ERR(name
);
3727 error
= mnt_want_write(path
.mnt
);
3731 mutex_lock_nested(&path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3732 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3733 error
= PTR_ERR(dentry
);
3736 if (!dentry
->d_inode
) {
3740 error
= security_path_rmdir(&path
, dentry
);
3743 error
= vfs_rmdir(path
.dentry
->d_inode
, dentry
);
3747 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3748 mnt_drop_write(path
.mnt
);
3752 if (retry_estale(error
, lookup_flags
)) {
3753 lookup_flags
|= LOOKUP_REVAL
;
3759 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
3761 return do_rmdir(AT_FDCWD
, pathname
);
3765 * vfs_unlink - unlink a filesystem object
3766 * @dir: parent directory
3768 * @delegated_inode: returns victim inode, if the inode is delegated.
3770 * The caller must hold dir->i_mutex.
3772 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
3773 * return a reference to the inode in delegated_inode. The caller
3774 * should then break the delegation on that inode and retry. Because
3775 * breaking a delegation may take a long time, the caller should drop
3776 * dir->i_mutex before doing so.
3778 * Alternatively, a caller may pass NULL for delegated_inode. This may
3779 * be appropriate for callers that expect the underlying filesystem not
3780 * to be NFS exported.
3782 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
, struct inode
**delegated_inode
)
3784 struct inode
*target
= dentry
->d_inode
;
3785 int error
= may_delete(dir
, dentry
, 0);
3790 if (!dir
->i_op
->unlink
)
3793 mutex_lock(&target
->i_mutex
);
3794 if (is_local_mountpoint(dentry
))
3797 error
= security_inode_unlink(dir
, dentry
);
3799 error
= try_break_deleg(target
, delegated_inode
);
3802 error
= dir
->i_op
->unlink(dir
, dentry
);
3805 detach_mounts(dentry
);
3810 mutex_unlock(&target
->i_mutex
);
3812 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
3813 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
3814 fsnotify_link_count(target
);
3820 EXPORT_SYMBOL(vfs_unlink
);
3823 * Make sure that the actual truncation of the file will occur outside its
3824 * directory's i_mutex. Truncate can take a long time if there is a lot of
3825 * writeout happening, and we don't want to prevent access to the directory
3826 * while waiting on the I/O.
3828 static long do_unlinkat(int dfd
, const char __user
*pathname
)
3831 struct filename
*name
;
3832 struct dentry
*dentry
;
3836 struct inode
*inode
= NULL
;
3837 struct inode
*delegated_inode
= NULL
;
3838 unsigned int lookup_flags
= 0;
3840 name
= user_path_parent(dfd
, pathname
,
3841 &path
, &last
, &type
, lookup_flags
);
3843 return PTR_ERR(name
);
3846 if (type
!= LAST_NORM
)
3849 error
= mnt_want_write(path
.mnt
);
3853 mutex_lock_nested(&path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3854 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3855 error
= PTR_ERR(dentry
);
3856 if (!IS_ERR(dentry
)) {
3857 /* Why not before? Because we want correct error value */
3858 if (last
.name
[last
.len
])
3860 inode
= dentry
->d_inode
;
3861 if (d_is_negative(dentry
))
3864 error
= security_path_unlink(&path
, dentry
);
3867 error
= vfs_unlink(path
.dentry
->d_inode
, dentry
, &delegated_inode
);
3871 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3873 iput(inode
); /* truncate the inode here */
3875 if (delegated_inode
) {
3876 error
= break_deleg_wait(&delegated_inode
);
3880 mnt_drop_write(path
.mnt
);
3884 if (retry_estale(error
, lookup_flags
)) {
3885 lookup_flags
|= LOOKUP_REVAL
;
3892 if (d_is_negative(dentry
))
3894 else if (d_is_dir(dentry
))
3901 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
3903 if ((flag
& ~AT_REMOVEDIR
) != 0)
3906 if (flag
& AT_REMOVEDIR
)
3907 return do_rmdir(dfd
, pathname
);
3909 return do_unlinkat(dfd
, pathname
);
3912 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
3914 return do_unlinkat(AT_FDCWD
, pathname
);
3917 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
3919 int error
= may_create(dir
, dentry
);
3924 if (!dir
->i_op
->symlink
)
3927 error
= security_inode_symlink(dir
, dentry
, oldname
);
3931 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
3933 fsnotify_create(dir
, dentry
);
3936 EXPORT_SYMBOL(vfs_symlink
);
3938 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
3939 int, newdfd
, const char __user
*, newname
)
3942 struct filename
*from
;
3943 struct dentry
*dentry
;
3945 unsigned int lookup_flags
= 0;
3947 from
= getname(oldname
);
3949 return PTR_ERR(from
);
3951 dentry
= user_path_create(newdfd
, newname
, &path
, lookup_flags
);
3952 error
= PTR_ERR(dentry
);
3956 error
= security_path_symlink(&path
, dentry
, from
->name
);
3958 error
= vfs_symlink(path
.dentry
->d_inode
, dentry
, from
->name
);
3959 done_path_create(&path
, dentry
);
3960 if (retry_estale(error
, lookup_flags
)) {
3961 lookup_flags
|= LOOKUP_REVAL
;
3969 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
3971 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
3975 * vfs_link - create a new link
3976 * @old_dentry: object to be linked
3978 * @new_dentry: where to create the new link
3979 * @delegated_inode: returns inode needing a delegation break
3981 * The caller must hold dir->i_mutex
3983 * If vfs_link discovers a delegation on the to-be-linked file in need
3984 * of breaking, it will return -EWOULDBLOCK and return a reference to the
3985 * inode in delegated_inode. The caller should then break the delegation
3986 * and retry. Because breaking a delegation may take a long time, the
3987 * caller should drop the i_mutex before doing so.
3989 * Alternatively, a caller may pass NULL for delegated_inode. This may
3990 * be appropriate for callers that expect the underlying filesystem not
3991 * to be NFS exported.
3993 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
, struct inode
**delegated_inode
)
3995 struct inode
*inode
= old_dentry
->d_inode
;
3996 unsigned max_links
= dir
->i_sb
->s_max_links
;
4002 error
= may_create(dir
, new_dentry
);
4006 if (dir
->i_sb
!= inode
->i_sb
)
4010 * A link to an append-only or immutable file cannot be created.
4012 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
4014 if (!dir
->i_op
->link
)
4016 if (S_ISDIR(inode
->i_mode
))
4019 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
4023 mutex_lock(&inode
->i_mutex
);
4024 /* Make sure we don't allow creating hardlink to an unlinked file */
4025 if (inode
->i_nlink
== 0 && !(inode
->i_state
& I_LINKABLE
))
4027 else if (max_links
&& inode
->i_nlink
>= max_links
)
4030 error
= try_break_deleg(inode
, delegated_inode
);
4032 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
4035 if (!error
&& (inode
->i_state
& I_LINKABLE
)) {
4036 spin_lock(&inode
->i_lock
);
4037 inode
->i_state
&= ~I_LINKABLE
;
4038 spin_unlock(&inode
->i_lock
);
4040 mutex_unlock(&inode
->i_mutex
);
4042 fsnotify_link(dir
, inode
, new_dentry
);
4045 EXPORT_SYMBOL(vfs_link
);
4048 * Hardlinks are often used in delicate situations. We avoid
4049 * security-related surprises by not following symlinks on the
4052 * We don't follow them on the oldname either to be compatible
4053 * with linux 2.0, and to avoid hard-linking to directories
4054 * and other special files. --ADM
4056 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
4057 int, newdfd
, const char __user
*, newname
, int, flags
)
4059 struct dentry
*new_dentry
;
4060 struct path old_path
, new_path
;
4061 struct inode
*delegated_inode
= NULL
;
4065 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0)
4068 * To use null names we require CAP_DAC_READ_SEARCH
4069 * This ensures that not everyone will be able to create
4070 * handlink using the passed filedescriptor.
4072 if (flags
& AT_EMPTY_PATH
) {
4073 if (!capable(CAP_DAC_READ_SEARCH
))
4078 if (flags
& AT_SYMLINK_FOLLOW
)
4079 how
|= LOOKUP_FOLLOW
;
4081 error
= user_path_at(olddfd
, oldname
, how
, &old_path
);
4085 new_dentry
= user_path_create(newdfd
, newname
, &new_path
,
4086 (how
& LOOKUP_REVAL
));
4087 error
= PTR_ERR(new_dentry
);
4088 if (IS_ERR(new_dentry
))
4092 if (old_path
.mnt
!= new_path
.mnt
)
4094 error
= may_linkat(&old_path
);
4095 if (unlikely(error
))
4097 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
4100 error
= vfs_link(old_path
.dentry
, new_path
.dentry
->d_inode
, new_dentry
, &delegated_inode
);
4102 done_path_create(&new_path
, new_dentry
);
4103 if (delegated_inode
) {
4104 error
= break_deleg_wait(&delegated_inode
);
4106 path_put(&old_path
);
4110 if (retry_estale(error
, how
)) {
4111 path_put(&old_path
);
4112 how
|= LOOKUP_REVAL
;
4116 path_put(&old_path
);
4121 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
4123 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4127 * vfs_rename - rename a filesystem object
4128 * @old_dir: parent of source
4129 * @old_dentry: source
4130 * @new_dir: parent of destination
4131 * @new_dentry: destination
4132 * @delegated_inode: returns an inode needing a delegation break
4133 * @flags: rename flags
4135 * The caller must hold multiple mutexes--see lock_rename()).
4137 * If vfs_rename discovers a delegation in need of breaking at either
4138 * the source or destination, it will return -EWOULDBLOCK and return a
4139 * reference to the inode in delegated_inode. The caller should then
4140 * break the delegation and retry. Because breaking a delegation may
4141 * take a long time, the caller should drop all locks before doing
4144 * Alternatively, a caller may pass NULL for delegated_inode. This may
4145 * be appropriate for callers that expect the underlying filesystem not
4146 * to be NFS exported.
4148 * The worst of all namespace operations - renaming directory. "Perverted"
4149 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4151 * a) we can get into loop creation.
4152 * b) race potential - two innocent renames can create a loop together.
4153 * That's where 4.4 screws up. Current fix: serialization on
4154 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
4156 * c) we have to lock _four_ objects - parents and victim (if it exists),
4157 * and source (if it is not a directory).
4158 * And that - after we got ->i_mutex on parents (until then we don't know
4159 * whether the target exists). Solution: try to be smart with locking
4160 * order for inodes. We rely on the fact that tree topology may change
4161 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
4162 * move will be locked. Thus we can rank directories by the tree
4163 * (ancestors first) and rank all non-directories after them.
4164 * That works since everybody except rename does "lock parent, lookup,
4165 * lock child" and rename is under ->s_vfs_rename_mutex.
4166 * HOWEVER, it relies on the assumption that any object with ->lookup()
4167 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4168 * we'd better make sure that there's no link(2) for them.
4169 * d) conversion from fhandle to dentry may come in the wrong moment - when
4170 * we are removing the target. Solution: we will have to grab ->i_mutex
4171 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
4172 * ->i_mutex on parents, which works but leads to some truly excessive
4175 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
4176 struct inode
*new_dir
, struct dentry
*new_dentry
,
4177 struct inode
**delegated_inode
, unsigned int flags
)
4180 bool is_dir
= d_is_dir(old_dentry
);
4181 const unsigned char *old_name
;
4182 struct inode
*source
= old_dentry
->d_inode
;
4183 struct inode
*target
= new_dentry
->d_inode
;
4184 bool new_is_dir
= false;
4185 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
4187 if (source
== target
)
4190 error
= may_delete(old_dir
, old_dentry
, is_dir
);
4195 error
= may_create(new_dir
, new_dentry
);
4197 new_is_dir
= d_is_dir(new_dentry
);
4199 if (!(flags
& RENAME_EXCHANGE
))
4200 error
= may_delete(new_dir
, new_dentry
, is_dir
);
4202 error
= may_delete(new_dir
, new_dentry
, new_is_dir
);
4207 if (!old_dir
->i_op
->rename
&& !old_dir
->i_op
->rename2
)
4210 if (flags
&& !old_dir
->i_op
->rename2
)
4214 * If we are going to change the parent - check write permissions,
4215 * we'll need to flip '..'.
4217 if (new_dir
!= old_dir
) {
4219 error
= inode_permission(source
, MAY_WRITE
);
4223 if ((flags
& RENAME_EXCHANGE
) && new_is_dir
) {
4224 error
= inode_permission(target
, MAY_WRITE
);
4230 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
,
4235 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
4237 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4238 lock_two_nondirectories(source
, target
);
4240 mutex_lock(&target
->i_mutex
);
4243 if (is_local_mountpoint(old_dentry
) || is_local_mountpoint(new_dentry
))
4246 if (max_links
&& new_dir
!= old_dir
) {
4248 if (is_dir
&& !new_is_dir
&& new_dir
->i_nlink
>= max_links
)
4250 if ((flags
& RENAME_EXCHANGE
) && !is_dir
&& new_is_dir
&&
4251 old_dir
->i_nlink
>= max_links
)
4254 if (is_dir
&& !(flags
& RENAME_EXCHANGE
) && target
)
4255 shrink_dcache_parent(new_dentry
);
4257 error
= try_break_deleg(source
, delegated_inode
);
4261 if (target
&& !new_is_dir
) {
4262 error
= try_break_deleg(target
, delegated_inode
);
4266 if (!old_dir
->i_op
->rename2
) {
4267 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
,
4268 new_dir
, new_dentry
);
4270 WARN_ON(old_dir
->i_op
->rename
!= NULL
);
4271 error
= old_dir
->i_op
->rename2(old_dir
, old_dentry
,
4272 new_dir
, new_dentry
, flags
);
4277 if (!(flags
& RENAME_EXCHANGE
) && target
) {
4279 target
->i_flags
|= S_DEAD
;
4280 dont_mount(new_dentry
);
4281 detach_mounts(new_dentry
);
4283 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
)) {
4284 if (!(flags
& RENAME_EXCHANGE
))
4285 d_move(old_dentry
, new_dentry
);
4287 d_exchange(old_dentry
, new_dentry
);
4290 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4291 unlock_two_nondirectories(source
, target
);
4293 mutex_unlock(&target
->i_mutex
);
4296 fsnotify_move(old_dir
, new_dir
, old_name
, is_dir
,
4297 !(flags
& RENAME_EXCHANGE
) ? target
: NULL
, old_dentry
);
4298 if (flags
& RENAME_EXCHANGE
) {
4299 fsnotify_move(new_dir
, old_dir
, old_dentry
->d_name
.name
,
4300 new_is_dir
, NULL
, new_dentry
);
4303 fsnotify_oldname_free(old_name
);
4307 EXPORT_SYMBOL(vfs_rename
);
4309 SYSCALL_DEFINE5(renameat2
, int, olddfd
, const char __user
*, oldname
,
4310 int, newdfd
, const char __user
*, newname
, unsigned int, flags
)
4312 struct dentry
*old_dentry
, *new_dentry
;
4313 struct dentry
*trap
;
4314 struct path old_path
, new_path
;
4315 struct qstr old_last
, new_last
;
4316 int old_type
, new_type
;
4317 struct inode
*delegated_inode
= NULL
;
4318 struct filename
*from
;
4319 struct filename
*to
;
4320 unsigned int lookup_flags
= 0, target_flags
= LOOKUP_RENAME_TARGET
;
4321 bool should_retry
= false;
4324 if (flags
& ~(RENAME_NOREPLACE
| RENAME_EXCHANGE
| RENAME_WHITEOUT
))
4327 if ((flags
& (RENAME_NOREPLACE
| RENAME_WHITEOUT
)) &&
4328 (flags
& RENAME_EXCHANGE
))
4331 if ((flags
& RENAME_WHITEOUT
) && !capable(CAP_MKNOD
))
4334 if (flags
& RENAME_EXCHANGE
)
4338 from
= user_path_parent(olddfd
, oldname
,
4339 &old_path
, &old_last
, &old_type
, lookup_flags
);
4341 error
= PTR_ERR(from
);
4345 to
= user_path_parent(newdfd
, newname
,
4346 &new_path
, &new_last
, &new_type
, lookup_flags
);
4348 error
= PTR_ERR(to
);
4353 if (old_path
.mnt
!= new_path
.mnt
)
4357 if (old_type
!= LAST_NORM
)
4360 if (flags
& RENAME_NOREPLACE
)
4362 if (new_type
!= LAST_NORM
)
4365 error
= mnt_want_write(old_path
.mnt
);
4370 trap
= lock_rename(new_path
.dentry
, old_path
.dentry
);
4372 old_dentry
= __lookup_hash(&old_last
, old_path
.dentry
, lookup_flags
);
4373 error
= PTR_ERR(old_dentry
);
4374 if (IS_ERR(old_dentry
))
4376 /* source must exist */
4378 if (d_is_negative(old_dentry
))
4380 new_dentry
= __lookup_hash(&new_last
, new_path
.dentry
, lookup_flags
| target_flags
);
4381 error
= PTR_ERR(new_dentry
);
4382 if (IS_ERR(new_dentry
))
4385 if ((flags
& RENAME_NOREPLACE
) && d_is_positive(new_dentry
))
4387 if (flags
& RENAME_EXCHANGE
) {
4389 if (d_is_negative(new_dentry
))
4392 if (!d_is_dir(new_dentry
)) {
4394 if (new_last
.name
[new_last
.len
])
4398 /* unless the source is a directory trailing slashes give -ENOTDIR */
4399 if (!d_is_dir(old_dentry
)) {
4401 if (old_last
.name
[old_last
.len
])
4403 if (!(flags
& RENAME_EXCHANGE
) && new_last
.name
[new_last
.len
])
4406 /* source should not be ancestor of target */
4408 if (old_dentry
== trap
)
4410 /* target should not be an ancestor of source */
4411 if (!(flags
& RENAME_EXCHANGE
))
4413 if (new_dentry
== trap
)
4416 error
= security_path_rename(&old_path
, old_dentry
,
4417 &new_path
, new_dentry
, flags
);
4420 error
= vfs_rename(old_path
.dentry
->d_inode
, old_dentry
,
4421 new_path
.dentry
->d_inode
, new_dentry
,
4422 &delegated_inode
, flags
);
4428 unlock_rename(new_path
.dentry
, old_path
.dentry
);
4429 if (delegated_inode
) {
4430 error
= break_deleg_wait(&delegated_inode
);
4434 mnt_drop_write(old_path
.mnt
);
4436 if (retry_estale(error
, lookup_flags
))
4437 should_retry
= true;
4438 path_put(&new_path
);
4441 path_put(&old_path
);
4444 should_retry
= false;
4445 lookup_flags
|= LOOKUP_REVAL
;
4452 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
4453 int, newdfd
, const char __user
*, newname
)
4455 return sys_renameat2(olddfd
, oldname
, newdfd
, newname
, 0);
4458 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
4460 return sys_renameat2(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4463 int vfs_whiteout(struct inode
*dir
, struct dentry
*dentry
)
4465 int error
= may_create(dir
, dentry
);
4469 if (!dir
->i_op
->mknod
)
4472 return dir
->i_op
->mknod(dir
, dentry
,
4473 S_IFCHR
| WHITEOUT_MODE
, WHITEOUT_DEV
);
4475 EXPORT_SYMBOL(vfs_whiteout
);
4477 int readlink_copy(char __user
*buffer
, int buflen
, const char *link
)
4479 int len
= PTR_ERR(link
);
4484 if (len
> (unsigned) buflen
)
4486 if (copy_to_user(buffer
, link
, len
))
4491 EXPORT_SYMBOL(readlink_copy
);
4494 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
4495 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
4496 * using) it for any given inode is up to filesystem.
4498 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4501 struct inode
*inode
= d_inode(dentry
);
4502 const char *link
= inode
->i_link
;
4506 link
= inode
->i_op
->follow_link(dentry
, &cookie
);
4508 return PTR_ERR(link
);
4510 res
= readlink_copy(buffer
, buflen
, link
);
4511 if (inode
->i_op
->put_link
)
4512 inode
->i_op
->put_link(inode
, cookie
);
4515 EXPORT_SYMBOL(generic_readlink
);
4517 /* get the link contents into pagecache */
4518 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
4522 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
4523 page
= read_mapping_page(mapping
, 0, NULL
);
4528 nd_terminate_link(kaddr
, dentry
->d_inode
->i_size
, PAGE_SIZE
- 1);
4532 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4534 struct page
*page
= NULL
;
4535 int res
= readlink_copy(buffer
, buflen
, page_getlink(dentry
, &page
));
4538 page_cache_release(page
);
4542 EXPORT_SYMBOL(page_readlink
);
4544 const char *page_follow_link_light(struct dentry
*dentry
, void **cookie
)
4546 struct page
*page
= NULL
;
4547 char *res
= page_getlink(dentry
, &page
);
4552 EXPORT_SYMBOL(page_follow_link_light
);
4554 void page_put_link(struct inode
*unused
, void *cookie
)
4556 struct page
*page
= cookie
;
4558 page_cache_release(page
);
4560 EXPORT_SYMBOL(page_put_link
);
4563 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
4565 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
4567 struct address_space
*mapping
= inode
->i_mapping
;
4572 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
4574 flags
|= AOP_FLAG_NOFS
;
4577 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
4578 flags
, &page
, &fsdata
);
4582 kaddr
= kmap_atomic(page
);
4583 memcpy(kaddr
, symname
, len
-1);
4584 kunmap_atomic(kaddr
);
4586 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
4593 mark_inode_dirty(inode
);
4598 EXPORT_SYMBOL(__page_symlink
);
4600 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
4602 return __page_symlink(inode
, symname
, len
,
4603 !(mapping_gfp_mask(inode
->i_mapping
) & __GFP_FS
));
4605 EXPORT_SYMBOL(page_symlink
);
4607 const struct inode_operations page_symlink_inode_operations
= {
4608 .readlink
= generic_readlink
,
4609 .follow_link
= page_follow_link_light
,
4610 .put_link
= page_put_link
,
4612 EXPORT_SYMBOL(page_symlink_inode_operations
);