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
;
510 } *stack
, internal
[EMBEDDED_LEVELS
];
513 static struct nameidata
*set_nameidata(struct nameidata
*p
)
515 struct nameidata
*old
= current
->nameidata
;
516 p
->stack
= p
->internal
;
517 p
->total_link_count
= old
? old
->total_link_count
: 0;
518 current
->nameidata
= p
;
522 static void restore_nameidata(struct nameidata
*old
)
524 struct nameidata
*now
= current
->nameidata
;
526 current
->nameidata
= old
;
528 old
->total_link_count
= now
->total_link_count
;
529 if (now
->stack
!= now
->internal
) {
531 now
->stack
= now
->internal
;
535 static int __nd_alloc_stack(struct nameidata
*nd
)
537 struct saved
*p
= kmalloc(MAXSYMLINKS
* sizeof(struct saved
),
541 memcpy(p
, nd
->internal
, sizeof(nd
->internal
));
546 static inline int nd_alloc_stack(struct nameidata
*nd
)
548 if (likely(nd
->depth
!= EMBEDDED_LEVELS
))
550 if (likely(nd
->stack
!= nd
->internal
))
552 return __nd_alloc_stack(nd
);
556 * Path walking has 2 modes, rcu-walk and ref-walk (see
557 * Documentation/filesystems/path-lookup.txt). In situations when we can't
558 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
559 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
560 * mode. Refcounts are grabbed at the last known good point before rcu-walk
561 * got stuck, so ref-walk may continue from there. If this is not successful
562 * (eg. a seqcount has changed), then failure is returned and it's up to caller
563 * to restart the path walk from the beginning in ref-walk mode.
566 static void terminate_walk(struct nameidata
*nd
);
569 * unlazy_walk - try to switch to ref-walk mode.
570 * @nd: nameidata pathwalk data
571 * @dentry: child of nd->path.dentry or NULL
572 * Returns: 0 on success, -ECHILD on failure
574 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
575 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
576 * @nd or NULL. Must be called from rcu-walk context.
578 static int unlazy_walk(struct nameidata
*nd
, struct dentry
*dentry
)
580 struct fs_struct
*fs
= current
->fs
;
581 struct dentry
*parent
= nd
->path
.dentry
;
583 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
586 * After legitimizing the bastards, terminate_walk()
587 * will do the right thing for non-RCU mode, and all our
588 * subsequent exit cases should rcu_read_unlock()
589 * before returning. Do vfsmount first; if dentry
590 * can't be legitimized, just set nd->path.dentry to NULL
591 * and rely on dput(NULL) being a no-op.
593 if (!legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
))
595 nd
->flags
&= ~LOOKUP_RCU
;
597 if (!lockref_get_not_dead(&parent
->d_lockref
)) {
598 nd
->path
.dentry
= NULL
;
603 * For a negative lookup, the lookup sequence point is the parents
604 * sequence point, and it only needs to revalidate the parent dentry.
606 * For a positive lookup, we need to move both the parent and the
607 * dentry from the RCU domain to be properly refcounted. And the
608 * sequence number in the dentry validates *both* dentry counters,
609 * since we checked the sequence number of the parent after we got
610 * the child sequence number. So we know the parent must still
611 * be valid if the child sequence number is still valid.
614 if (read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
616 BUG_ON(nd
->inode
!= parent
->d_inode
);
618 if (!lockref_get_not_dead(&dentry
->d_lockref
))
620 if (read_seqcount_retry(&dentry
->d_seq
, nd
->seq
))
625 * Sequence counts matched. Now make sure that the root is
626 * still valid and get it if required.
628 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
629 spin_lock(&fs
->lock
);
630 if (nd
->root
.mnt
!= fs
->root
.mnt
|| nd
->root
.dentry
!= fs
->root
.dentry
)
631 goto unlock_and_drop_dentry
;
633 spin_unlock(&fs
->lock
);
639 unlock_and_drop_dentry
:
640 spin_unlock(&fs
->lock
);
648 if (!(nd
->flags
& LOOKUP_ROOT
))
653 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
655 return dentry
->d_op
->d_revalidate(dentry
, flags
);
659 * complete_walk - successful completion of path walk
660 * @nd: pointer nameidata
662 * If we had been in RCU mode, drop out of it and legitimize nd->path.
663 * Revalidate the final result, unless we'd already done that during
664 * the path walk or the filesystem doesn't ask for it. Return 0 on
665 * success, -error on failure. In case of failure caller does not
666 * need to drop nd->path.
668 static int complete_walk(struct nameidata
*nd
)
670 struct dentry
*dentry
= nd
->path
.dentry
;
673 if (nd
->flags
& LOOKUP_RCU
) {
674 if (!(nd
->flags
& LOOKUP_ROOT
))
676 if (unlikely(unlazy_walk(nd
, NULL
))) {
682 if (likely(!(nd
->flags
& LOOKUP_JUMPED
)))
685 if (likely(!(dentry
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)))
688 status
= dentry
->d_op
->d_weak_revalidate(dentry
, nd
->flags
);
699 static __always_inline
void set_root(struct nameidata
*nd
)
701 get_fs_root(current
->fs
, &nd
->root
);
704 static __always_inline
unsigned set_root_rcu(struct nameidata
*nd
)
706 struct fs_struct
*fs
= current
->fs
;
710 seq
= read_seqcount_begin(&fs
->seq
);
712 res
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
713 } while (read_seqcount_retry(&fs
->seq
, seq
));
717 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
720 if (path
->mnt
!= nd
->path
.mnt
)
724 static inline void path_to_nameidata(const struct path
*path
,
725 struct nameidata
*nd
)
727 if (!(nd
->flags
& LOOKUP_RCU
)) {
728 dput(nd
->path
.dentry
);
729 if (nd
->path
.mnt
!= path
->mnt
)
730 mntput(nd
->path
.mnt
);
732 nd
->path
.mnt
= path
->mnt
;
733 nd
->path
.dentry
= path
->dentry
;
737 * Helper to directly jump to a known parsed path from ->follow_link,
738 * caller must have taken a reference to path beforehand.
740 void nd_jump_link(struct path
*path
)
742 struct nameidata
*nd
= current
->nameidata
;
746 nd
->inode
= nd
->path
.dentry
->d_inode
;
747 nd
->flags
|= LOOKUP_JUMPED
;
750 static inline void put_link(struct nameidata
*nd
)
752 struct saved
*last
= nd
->stack
+ --nd
->depth
;
753 struct inode
*inode
= last
->link
.dentry
->d_inode
;
754 if (last
->cookie
&& inode
->i_op
->put_link
)
755 inode
->i_op
->put_link(last
->link
.dentry
, last
->cookie
);
756 path_put(&last
->link
);
759 int sysctl_protected_symlinks __read_mostly
= 0;
760 int sysctl_protected_hardlinks __read_mostly
= 0;
763 * may_follow_link - Check symlink following for unsafe situations
764 * @nd: nameidata pathwalk data
766 * In the case of the sysctl_protected_symlinks sysctl being enabled,
767 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
768 * in a sticky world-writable directory. This is to protect privileged
769 * processes from failing races against path names that may change out
770 * from under them by way of other users creating malicious symlinks.
771 * It will permit symlinks to be followed only when outside a sticky
772 * world-writable directory, or when the uid of the symlink and follower
773 * match, or when the directory owner matches the symlink's owner.
775 * Returns 0 if following the symlink is allowed, -ve on error.
777 static inline int may_follow_link(struct nameidata
*nd
)
779 const struct inode
*inode
;
780 const struct inode
*parent
;
782 if (!sysctl_protected_symlinks
)
785 /* Allowed if owner and follower match. */
786 inode
= nd
->stack
[0].link
.dentry
->d_inode
;
787 if (uid_eq(current_cred()->fsuid
, inode
->i_uid
))
790 /* Allowed if parent directory not sticky and world-writable. */
791 parent
= nd
->path
.dentry
->d_inode
;
792 if ((parent
->i_mode
& (S_ISVTX
|S_IWOTH
)) != (S_ISVTX
|S_IWOTH
))
795 /* Allowed if parent directory and link owner match. */
796 if (uid_eq(parent
->i_uid
, inode
->i_uid
))
799 audit_log_link_denied("follow_link", &nd
->stack
[0].link
);
804 * safe_hardlink_source - Check for safe hardlink conditions
805 * @inode: the source inode to hardlink from
807 * Return false if at least one of the following conditions:
808 * - inode is not a regular file
810 * - inode is setgid and group-exec
811 * - access failure for read and write
813 * Otherwise returns true.
815 static bool safe_hardlink_source(struct inode
*inode
)
817 umode_t mode
= inode
->i_mode
;
819 /* Special files should not get pinned to the filesystem. */
823 /* Setuid files should not get pinned to the filesystem. */
827 /* Executable setgid files should not get pinned to the filesystem. */
828 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
))
831 /* Hardlinking to unreadable or unwritable sources is dangerous. */
832 if (inode_permission(inode
, MAY_READ
| MAY_WRITE
))
839 * may_linkat - Check permissions for creating a hardlink
840 * @link: the source to hardlink from
842 * Block hardlink when all of:
843 * - sysctl_protected_hardlinks enabled
844 * - fsuid does not match inode
845 * - hardlink source is unsafe (see safe_hardlink_source() above)
848 * Returns 0 if successful, -ve on error.
850 static int may_linkat(struct path
*link
)
852 const struct cred
*cred
;
855 if (!sysctl_protected_hardlinks
)
858 cred
= current_cred();
859 inode
= link
->dentry
->d_inode
;
861 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
862 * otherwise, it must be a safe source.
864 if (uid_eq(cred
->fsuid
, inode
->i_uid
) || safe_hardlink_source(inode
) ||
868 audit_log_link_denied("linkat", link
);
872 static __always_inline
873 const char *get_link(struct nameidata
*nd
)
875 struct saved
*last
= nd
->stack
+ nd
->depth
- 1;
876 struct dentry
*dentry
= last
->link
.dentry
;
877 struct inode
*inode
= dentry
->d_inode
;
881 BUG_ON(nd
->flags
& LOOKUP_RCU
);
885 touch_atime(&last
->link
);
887 error
= security_inode_follow_link(dentry
);
889 return ERR_PTR(error
);
891 nd
->last_type
= LAST_BIND
;
894 res
= inode
->i_op
->follow_link(dentry
, &last
->cookie
);
895 if (IS_ERR_OR_NULL(res
)) {
906 nd
->inode
= nd
->path
.dentry
->d_inode
;
907 nd
->flags
|= LOOKUP_JUMPED
;
908 while (unlikely(*++res
== '/'))
916 static int follow_up_rcu(struct path
*path
)
918 struct mount
*mnt
= real_mount(path
->mnt
);
919 struct mount
*parent
;
920 struct dentry
*mountpoint
;
922 parent
= mnt
->mnt_parent
;
923 if (&parent
->mnt
== path
->mnt
)
925 mountpoint
= mnt
->mnt_mountpoint
;
926 path
->dentry
= mountpoint
;
927 path
->mnt
= &parent
->mnt
;
932 * follow_up - Find the mountpoint of path's vfsmount
934 * Given a path, find the mountpoint of its source file system.
935 * Replace @path with the path of the mountpoint in the parent mount.
938 * Return 1 if we went up a level and 0 if we were already at the
941 int follow_up(struct path
*path
)
943 struct mount
*mnt
= real_mount(path
->mnt
);
944 struct mount
*parent
;
945 struct dentry
*mountpoint
;
947 read_seqlock_excl(&mount_lock
);
948 parent
= mnt
->mnt_parent
;
950 read_sequnlock_excl(&mount_lock
);
953 mntget(&parent
->mnt
);
954 mountpoint
= dget(mnt
->mnt_mountpoint
);
955 read_sequnlock_excl(&mount_lock
);
957 path
->dentry
= mountpoint
;
959 path
->mnt
= &parent
->mnt
;
962 EXPORT_SYMBOL(follow_up
);
965 * Perform an automount
966 * - return -EISDIR to tell follow_managed() to stop and return the path we
969 static int follow_automount(struct path
*path
, struct nameidata
*nd
,
972 struct vfsmount
*mnt
;
975 if (!path
->dentry
->d_op
|| !path
->dentry
->d_op
->d_automount
)
978 /* We don't want to mount if someone's just doing a stat -
979 * unless they're stat'ing a directory and appended a '/' to
982 * We do, however, want to mount if someone wants to open or
983 * create a file of any type under the mountpoint, wants to
984 * traverse through the mountpoint or wants to open the
985 * mounted directory. Also, autofs may mark negative dentries
986 * as being automount points. These will need the attentions
987 * of the daemon to instantiate them before they can be used.
989 if (!(nd
->flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
990 LOOKUP_OPEN
| LOOKUP_CREATE
| LOOKUP_AUTOMOUNT
)) &&
991 path
->dentry
->d_inode
)
994 nd
->total_link_count
++;
995 if (nd
->total_link_count
>= 40)
998 mnt
= path
->dentry
->d_op
->d_automount(path
);
1001 * The filesystem is allowed to return -EISDIR here to indicate
1002 * it doesn't want to automount. For instance, autofs would do
1003 * this so that its userspace daemon can mount on this dentry.
1005 * However, we can only permit this if it's a terminal point in
1006 * the path being looked up; if it wasn't then the remainder of
1007 * the path is inaccessible and we should say so.
1009 if (PTR_ERR(mnt
) == -EISDIR
&& (nd
->flags
& LOOKUP_PARENT
))
1011 return PTR_ERR(mnt
);
1014 if (!mnt
) /* mount collision */
1017 if (!*need_mntput
) {
1018 /* lock_mount() may release path->mnt on error */
1020 *need_mntput
= true;
1022 err
= finish_automount(mnt
, path
);
1026 /* Someone else made a mount here whilst we were busy */
1031 path
->dentry
= dget(mnt
->mnt_root
);
1040 * Handle a dentry that is managed in some way.
1041 * - Flagged for transit management (autofs)
1042 * - Flagged as mountpoint
1043 * - Flagged as automount point
1045 * This may only be called in refwalk mode.
1047 * Serialization is taken care of in namespace.c
1049 static int follow_managed(struct path
*path
, struct nameidata
*nd
)
1051 struct vfsmount
*mnt
= path
->mnt
; /* held by caller, must be left alone */
1053 bool need_mntput
= false;
1056 /* Given that we're not holding a lock here, we retain the value in a
1057 * local variable for each dentry as we look at it so that we don't see
1058 * the components of that value change under us */
1059 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1060 managed
&= DCACHE_MANAGED_DENTRY
,
1061 unlikely(managed
!= 0)) {
1062 /* Allow the filesystem to manage the transit without i_mutex
1064 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1065 BUG_ON(!path
->dentry
->d_op
);
1066 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1067 ret
= path
->dentry
->d_op
->d_manage(path
->dentry
, false);
1072 /* Transit to a mounted filesystem. */
1073 if (managed
& DCACHE_MOUNTED
) {
1074 struct vfsmount
*mounted
= lookup_mnt(path
);
1079 path
->mnt
= mounted
;
1080 path
->dentry
= dget(mounted
->mnt_root
);
1085 /* Something is mounted on this dentry in another
1086 * namespace and/or whatever was mounted there in this
1087 * namespace got unmounted before lookup_mnt() could
1091 /* Handle an automount point */
1092 if (managed
& DCACHE_NEED_AUTOMOUNT
) {
1093 ret
= follow_automount(path
, nd
, &need_mntput
);
1099 /* We didn't change the current path point */
1103 if (need_mntput
&& path
->mnt
== mnt
)
1108 nd
->flags
|= LOOKUP_JUMPED
;
1109 if (unlikely(ret
< 0))
1110 path_put_conditional(path
, nd
);
1114 int follow_down_one(struct path
*path
)
1116 struct vfsmount
*mounted
;
1118 mounted
= lookup_mnt(path
);
1122 path
->mnt
= mounted
;
1123 path
->dentry
= dget(mounted
->mnt_root
);
1128 EXPORT_SYMBOL(follow_down_one
);
1130 static inline int managed_dentry_rcu(struct dentry
*dentry
)
1132 return (dentry
->d_flags
& DCACHE_MANAGE_TRANSIT
) ?
1133 dentry
->d_op
->d_manage(dentry
, true) : 0;
1137 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1138 * we meet a managed dentry that would need blocking.
1140 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
,
1141 struct inode
**inode
)
1144 struct mount
*mounted
;
1146 * Don't forget we might have a non-mountpoint managed dentry
1147 * that wants to block transit.
1149 switch (managed_dentry_rcu(path
->dentry
)) {
1159 if (!d_mountpoint(path
->dentry
))
1160 return !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1162 mounted
= __lookup_mnt(path
->mnt
, path
->dentry
);
1165 path
->mnt
= &mounted
->mnt
;
1166 path
->dentry
= mounted
->mnt
.mnt_root
;
1167 nd
->flags
|= LOOKUP_JUMPED
;
1168 nd
->seq
= read_seqcount_begin(&path
->dentry
->d_seq
);
1170 * Update the inode too. We don't need to re-check the
1171 * dentry sequence number here after this d_inode read,
1172 * because a mount-point is always pinned.
1174 *inode
= path
->dentry
->d_inode
;
1176 return !read_seqretry(&mount_lock
, nd
->m_seq
) &&
1177 !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1180 static int follow_dotdot_rcu(struct nameidata
*nd
)
1182 struct inode
*inode
= nd
->inode
;
1187 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1188 nd
->path
.mnt
== nd
->root
.mnt
) {
1191 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1192 struct dentry
*old
= nd
->path
.dentry
;
1193 struct dentry
*parent
= old
->d_parent
;
1196 inode
= parent
->d_inode
;
1197 seq
= read_seqcount_begin(&parent
->d_seq
);
1198 if (read_seqcount_retry(&old
->d_seq
, nd
->seq
))
1200 nd
->path
.dentry
= parent
;
1204 if (!follow_up_rcu(&nd
->path
))
1206 inode
= nd
->path
.dentry
->d_inode
;
1207 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1209 while (d_mountpoint(nd
->path
.dentry
)) {
1210 struct mount
*mounted
;
1211 mounted
= __lookup_mnt(nd
->path
.mnt
, nd
->path
.dentry
);
1214 nd
->path
.mnt
= &mounted
->mnt
;
1215 nd
->path
.dentry
= mounted
->mnt
.mnt_root
;
1216 inode
= nd
->path
.dentry
->d_inode
;
1217 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1218 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1229 * Follow down to the covering mount currently visible to userspace. At each
1230 * point, the filesystem owning that dentry may be queried as to whether the
1231 * caller is permitted to proceed or not.
1233 int follow_down(struct path
*path
)
1238 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1239 unlikely(managed
& DCACHE_MANAGED_DENTRY
)) {
1240 /* Allow the filesystem to manage the transit without i_mutex
1243 * We indicate to the filesystem if someone is trying to mount
1244 * something here. This gives autofs the chance to deny anyone
1245 * other than its daemon the right to mount on its
1248 * The filesystem may sleep at this point.
1250 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1251 BUG_ON(!path
->dentry
->d_op
);
1252 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1253 ret
= path
->dentry
->d_op
->d_manage(
1254 path
->dentry
, false);
1256 return ret
== -EISDIR
? 0 : ret
;
1259 /* Transit to a mounted filesystem. */
1260 if (managed
& DCACHE_MOUNTED
) {
1261 struct vfsmount
*mounted
= lookup_mnt(path
);
1266 path
->mnt
= mounted
;
1267 path
->dentry
= dget(mounted
->mnt_root
);
1271 /* Don't handle automount points here */
1276 EXPORT_SYMBOL(follow_down
);
1279 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1281 static void follow_mount(struct path
*path
)
1283 while (d_mountpoint(path
->dentry
)) {
1284 struct vfsmount
*mounted
= lookup_mnt(path
);
1289 path
->mnt
= mounted
;
1290 path
->dentry
= dget(mounted
->mnt_root
);
1294 static void follow_dotdot(struct nameidata
*nd
)
1300 struct dentry
*old
= nd
->path
.dentry
;
1302 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1303 nd
->path
.mnt
== nd
->root
.mnt
) {
1306 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1307 /* rare case of legitimate dget_parent()... */
1308 nd
->path
.dentry
= dget_parent(nd
->path
.dentry
);
1312 if (!follow_up(&nd
->path
))
1315 follow_mount(&nd
->path
);
1316 nd
->inode
= nd
->path
.dentry
->d_inode
;
1320 * This looks up the name in dcache, possibly revalidates the old dentry and
1321 * allocates a new one if not found or not valid. In the need_lookup argument
1322 * returns whether i_op->lookup is necessary.
1324 * dir->d_inode->i_mutex must be held
1326 static struct dentry
*lookup_dcache(struct qstr
*name
, struct dentry
*dir
,
1327 unsigned int flags
, bool *need_lookup
)
1329 struct dentry
*dentry
;
1332 *need_lookup
= false;
1333 dentry
= d_lookup(dir
, name
);
1335 if (dentry
->d_flags
& DCACHE_OP_REVALIDATE
) {
1336 error
= d_revalidate(dentry
, flags
);
1337 if (unlikely(error
<= 0)) {
1340 return ERR_PTR(error
);
1342 d_invalidate(dentry
);
1351 dentry
= d_alloc(dir
, name
);
1352 if (unlikely(!dentry
))
1353 return ERR_PTR(-ENOMEM
);
1355 *need_lookup
= true;
1361 * Call i_op->lookup on the dentry. The dentry must be negative and
1364 * dir->d_inode->i_mutex must be held
1366 static struct dentry
*lookup_real(struct inode
*dir
, struct dentry
*dentry
,
1371 /* Don't create child dentry for a dead directory. */
1372 if (unlikely(IS_DEADDIR(dir
))) {
1374 return ERR_PTR(-ENOENT
);
1377 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1378 if (unlikely(old
)) {
1385 static struct dentry
*__lookup_hash(struct qstr
*name
,
1386 struct dentry
*base
, unsigned int flags
)
1389 struct dentry
*dentry
;
1391 dentry
= lookup_dcache(name
, base
, flags
, &need_lookup
);
1395 return lookup_real(base
->d_inode
, dentry
, flags
);
1399 * It's more convoluted than I'd like it to be, but... it's still fairly
1400 * small and for now I'd prefer to have fast path as straight as possible.
1401 * It _is_ time-critical.
1403 static int lookup_fast(struct nameidata
*nd
,
1404 struct path
*path
, struct inode
**inode
)
1406 struct vfsmount
*mnt
= nd
->path
.mnt
;
1407 struct dentry
*dentry
, *parent
= nd
->path
.dentry
;
1413 * Rename seqlock is not required here because in the off chance
1414 * of a false negative due to a concurrent rename, we're going to
1415 * do the non-racy lookup, below.
1417 if (nd
->flags
& LOOKUP_RCU
) {
1420 dentry
= __d_lookup_rcu(parent
, &nd
->last
, &seq
);
1425 * This sequence count validates that the inode matches
1426 * the dentry name information from lookup.
1428 *inode
= dentry
->d_inode
;
1429 negative
= d_is_negative(dentry
);
1430 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
1436 * This sequence count validates that the parent had no
1437 * changes while we did the lookup of the dentry above.
1439 * The memory barrier in read_seqcount_begin of child is
1440 * enough, we can use __read_seqcount_retry here.
1442 if (__read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
1446 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
)) {
1447 status
= d_revalidate(dentry
, nd
->flags
);
1448 if (unlikely(status
<= 0)) {
1449 if (status
!= -ECHILD
)
1455 path
->dentry
= dentry
;
1456 if (likely(__follow_mount_rcu(nd
, path
, inode
)))
1459 if (unlazy_walk(nd
, dentry
))
1462 dentry
= __d_lookup(parent
, &nd
->last
);
1465 if (unlikely(!dentry
))
1468 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
) && need_reval
)
1469 status
= d_revalidate(dentry
, nd
->flags
);
1470 if (unlikely(status
<= 0)) {
1475 d_invalidate(dentry
);
1480 if (unlikely(d_is_negative(dentry
))) {
1485 path
->dentry
= dentry
;
1486 err
= follow_managed(path
, nd
);
1488 *inode
= path
->dentry
->d_inode
;
1495 /* Fast lookup failed, do it the slow way */
1496 static int lookup_slow(struct nameidata
*nd
, struct path
*path
)
1498 struct dentry
*dentry
, *parent
;
1500 parent
= nd
->path
.dentry
;
1501 BUG_ON(nd
->inode
!= parent
->d_inode
);
1503 mutex_lock(&parent
->d_inode
->i_mutex
);
1504 dentry
= __lookup_hash(&nd
->last
, parent
, nd
->flags
);
1505 mutex_unlock(&parent
->d_inode
->i_mutex
);
1507 return PTR_ERR(dentry
);
1508 path
->mnt
= nd
->path
.mnt
;
1509 path
->dentry
= dentry
;
1510 return follow_managed(path
, nd
);
1513 static inline int may_lookup(struct nameidata
*nd
)
1515 if (nd
->flags
& LOOKUP_RCU
) {
1516 int err
= inode_permission(nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1519 if (unlazy_walk(nd
, NULL
))
1522 return inode_permission(nd
->inode
, MAY_EXEC
);
1525 static inline int handle_dots(struct nameidata
*nd
, int type
)
1527 if (type
== LAST_DOTDOT
) {
1528 if (nd
->flags
& LOOKUP_RCU
) {
1529 return follow_dotdot_rcu(nd
);
1536 static void terminate_walk(struct nameidata
*nd
)
1538 if (!(nd
->flags
& LOOKUP_RCU
)) {
1539 path_put(&nd
->path
);
1541 nd
->flags
&= ~LOOKUP_RCU
;
1542 if (!(nd
->flags
& LOOKUP_ROOT
))
1543 nd
->root
.mnt
= NULL
;
1546 while (unlikely(nd
->depth
))
1550 static int pick_link(struct nameidata
*nd
, struct path
*link
)
1554 if (unlikely(nd
->total_link_count
++ >= MAXSYMLINKS
)) {
1555 path_to_nameidata(link
, nd
);
1558 if (nd
->flags
& LOOKUP_RCU
) {
1559 if (unlikely(nd
->path
.mnt
!= link
->mnt
||
1560 unlazy_walk(nd
, link
->dentry
))) {
1564 if (link
->mnt
== nd
->path
.mnt
)
1566 error
= nd_alloc_stack(nd
);
1567 if (unlikely(error
)) {
1572 last
= nd
->stack
+ nd
->depth
++;
1574 last
->cookie
= NULL
;
1579 * Do we need to follow links? We _really_ want to be able
1580 * to do this check without having to look at inode->i_op,
1581 * so we keep a cache of "no, this doesn't need follow_link"
1582 * for the common case.
1584 static inline int should_follow_link(struct nameidata
*nd
, struct path
*link
, int follow
)
1586 if (likely(!d_is_symlink(link
->dentry
)))
1590 return pick_link(nd
, link
);
1593 enum {WALK_GET
= 1, WALK_PUT
= 2};
1595 static int walk_component(struct nameidata
*nd
, int flags
)
1598 struct inode
*inode
;
1601 * "." and ".." are special - ".." especially so because it has
1602 * to be able to know about the current root directory and
1603 * parent relationships.
1605 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
1606 err
= handle_dots(nd
, nd
->last_type
);
1607 if (flags
& WALK_PUT
)
1611 err
= lookup_fast(nd
, &path
, &inode
);
1612 if (unlikely(err
)) {
1616 err
= lookup_slow(nd
, &path
);
1620 inode
= path
.dentry
->d_inode
;
1622 if (d_is_negative(path
.dentry
))
1626 if (flags
& WALK_PUT
)
1628 err
= should_follow_link(nd
, &path
, flags
& WALK_GET
);
1631 path_to_nameidata(&path
, nd
);
1636 path_to_nameidata(&path
, nd
);
1641 * We can do the critical dentry name comparison and hashing
1642 * operations one word at a time, but we are limited to:
1644 * - Architectures with fast unaligned word accesses. We could
1645 * do a "get_unaligned()" if this helps and is sufficiently
1648 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1649 * do not trap on the (extremely unlikely) case of a page
1650 * crossing operation.
1652 * - Furthermore, we need an efficient 64-bit compile for the
1653 * 64-bit case in order to generate the "number of bytes in
1654 * the final mask". Again, that could be replaced with a
1655 * efficient population count instruction or similar.
1657 #ifdef CONFIG_DCACHE_WORD_ACCESS
1659 #include <asm/word-at-a-time.h>
1663 static inline unsigned int fold_hash(unsigned long hash
)
1665 return hash_64(hash
, 32);
1668 #else /* 32-bit case */
1670 #define fold_hash(x) (x)
1674 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1676 unsigned long a
, mask
;
1677 unsigned long hash
= 0;
1680 a
= load_unaligned_zeropad(name
);
1681 if (len
< sizeof(unsigned long))
1685 name
+= sizeof(unsigned long);
1686 len
-= sizeof(unsigned long);
1690 mask
= bytemask_from_count(len
);
1693 return fold_hash(hash
);
1695 EXPORT_SYMBOL(full_name_hash
);
1698 * Calculate the length and hash of the path component, and
1699 * return the "hash_len" as the result.
1701 static inline u64
hash_name(const char *name
)
1703 unsigned long a
, b
, adata
, bdata
, mask
, hash
, len
;
1704 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
1707 len
= -sizeof(unsigned long);
1709 hash
= (hash
+ a
) * 9;
1710 len
+= sizeof(unsigned long);
1711 a
= load_unaligned_zeropad(name
+len
);
1712 b
= a
^ REPEAT_BYTE('/');
1713 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
1715 adata
= prep_zero_mask(a
, adata
, &constants
);
1716 bdata
= prep_zero_mask(b
, bdata
, &constants
);
1718 mask
= create_zero_mask(adata
| bdata
);
1720 hash
+= a
& zero_bytemask(mask
);
1721 len
+= find_zero(mask
);
1722 return hashlen_create(fold_hash(hash
), len
);
1727 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1729 unsigned long hash
= init_name_hash();
1731 hash
= partial_name_hash(*name
++, hash
);
1732 return end_name_hash(hash
);
1734 EXPORT_SYMBOL(full_name_hash
);
1737 * We know there's a real path component here of at least
1740 static inline u64
hash_name(const char *name
)
1742 unsigned long hash
= init_name_hash();
1743 unsigned long len
= 0, c
;
1745 c
= (unsigned char)*name
;
1748 hash
= partial_name_hash(c
, hash
);
1749 c
= (unsigned char)name
[len
];
1750 } while (c
&& c
!= '/');
1751 return hashlen_create(end_name_hash(hash
), len
);
1758 * This is the basic name resolution function, turning a pathname into
1759 * the final dentry. We expect 'base' to be positive and a directory.
1761 * Returns 0 and nd will have valid dentry and mnt on success.
1762 * Returns error and drops reference to input namei data on failure.
1764 static int link_path_walk(const char *name
, struct nameidata
*nd
)
1773 /* At this point we know we have a real path component. */
1778 err
= may_lookup(nd
);
1782 hash_len
= hash_name(name
);
1785 if (name
[0] == '.') switch (hashlen_len(hash_len
)) {
1787 if (name
[1] == '.') {
1789 nd
->flags
|= LOOKUP_JUMPED
;
1795 if (likely(type
== LAST_NORM
)) {
1796 struct dentry
*parent
= nd
->path
.dentry
;
1797 nd
->flags
&= ~LOOKUP_JUMPED
;
1798 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
1799 struct qstr
this = { { .hash_len
= hash_len
}, .name
= name
};
1800 err
= parent
->d_op
->d_hash(parent
, &this);
1803 hash_len
= this.hash_len
;
1808 nd
->last
.hash_len
= hash_len
;
1809 nd
->last
.name
= name
;
1810 nd
->last_type
= type
;
1812 name
+= hashlen_len(hash_len
);
1816 * If it wasn't NUL, we know it was '/'. Skip that
1817 * slash, and continue until no more slashes.
1821 } while (unlikely(*name
== '/'));
1822 if (unlikely(!*name
)) {
1824 /* pathname body, done */
1827 name
= nd
->stack
[nd
->depth
- 1].name
;
1828 /* trailing symlink, done */
1831 /* last component of nested symlink */
1832 err
= walk_component(nd
, WALK_GET
| WALK_PUT
);
1834 err
= walk_component(nd
, WALK_GET
);
1840 const char *s
= get_link(nd
);
1842 if (unlikely(IS_ERR(s
))) {
1851 nd
->stack
[nd
->depth
- 1].name
= name
;
1856 if (!d_can_lookup(nd
->path
.dentry
)) {
1865 static const char *path_init(int dfd
, const struct filename
*name
,
1866 unsigned int flags
, struct nameidata
*nd
)
1869 const char *s
= name
->name
;
1871 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1872 nd
->flags
= flags
| LOOKUP_JUMPED
| LOOKUP_PARENT
;
1874 nd
->total_link_count
= 0;
1875 if (flags
& LOOKUP_ROOT
) {
1876 struct dentry
*root
= nd
->root
.dentry
;
1877 struct inode
*inode
= root
->d_inode
;
1879 if (!d_can_lookup(root
))
1880 return ERR_PTR(-ENOTDIR
);
1881 retval
= inode_permission(inode
, MAY_EXEC
);
1883 return ERR_PTR(retval
);
1885 nd
->path
= nd
->root
;
1887 if (flags
& LOOKUP_RCU
) {
1889 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1890 nd
->m_seq
= read_seqbegin(&mount_lock
);
1892 path_get(&nd
->path
);
1897 nd
->root
.mnt
= NULL
;
1899 nd
->m_seq
= read_seqbegin(&mount_lock
);
1901 if (flags
& LOOKUP_RCU
) {
1903 nd
->seq
= set_root_rcu(nd
);
1906 path_get(&nd
->root
);
1908 nd
->path
= nd
->root
;
1909 } else if (dfd
== AT_FDCWD
) {
1910 if (flags
& LOOKUP_RCU
) {
1911 struct fs_struct
*fs
= current
->fs
;
1917 seq
= read_seqcount_begin(&fs
->seq
);
1919 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1920 } while (read_seqcount_retry(&fs
->seq
, seq
));
1922 get_fs_pwd(current
->fs
, &nd
->path
);
1925 /* Caller must check execute permissions on the starting path component */
1926 struct fd f
= fdget_raw(dfd
);
1927 struct dentry
*dentry
;
1930 return ERR_PTR(-EBADF
);
1932 dentry
= f
.file
->f_path
.dentry
;
1935 if (!d_can_lookup(dentry
)) {
1937 return ERR_PTR(-ENOTDIR
);
1941 nd
->path
= f
.file
->f_path
;
1942 if (flags
& LOOKUP_RCU
) {
1944 nd
->inode
= nd
->path
.dentry
->d_inode
;
1945 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1947 path_get(&nd
->path
);
1948 nd
->inode
= nd
->path
.dentry
->d_inode
;
1954 nd
->inode
= nd
->path
.dentry
->d_inode
;
1955 if (!(flags
& LOOKUP_RCU
))
1957 if (likely(!read_seqcount_retry(&nd
->path
.dentry
->d_seq
, nd
->seq
)))
1959 if (!(nd
->flags
& LOOKUP_ROOT
))
1960 nd
->root
.mnt
= NULL
;
1962 return ERR_PTR(-ECHILD
);
1965 static void path_cleanup(struct nameidata
*nd
)
1967 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
1968 path_put(&nd
->root
);
1969 nd
->root
.mnt
= NULL
;
1973 static int trailing_symlink(struct nameidata
*nd
)
1976 int error
= may_follow_link(nd
);
1977 if (unlikely(error
)) {
1981 nd
->flags
|= LOOKUP_PARENT
;
1982 nd
->stack
[0].name
= NULL
;
1984 if (unlikely(IS_ERR(s
))) {
1990 return link_path_walk(s
, nd
);
1993 static inline int lookup_last(struct nameidata
*nd
)
1996 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
1997 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
1999 nd
->flags
&= ~LOOKUP_PARENT
;
2000 err
= walk_component(nd
,
2001 nd
->flags
& LOOKUP_FOLLOW
2003 ? WALK_PUT
| WALK_GET
2011 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2012 static int path_lookupat(int dfd
, const struct filename
*name
,
2013 unsigned int flags
, struct nameidata
*nd
)
2015 const char *s
= path_init(dfd
, name
, flags
, nd
);
2020 err
= link_path_walk(s
, nd
);
2022 while ((err
= lookup_last(nd
)) > 0) {
2023 err
= trailing_symlink(nd
);
2030 err
= complete_walk(nd
);
2032 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
) {
2033 if (!d_can_lookup(nd
->path
.dentry
)) {
2034 path_put(&nd
->path
);
2043 static int filename_lookup(int dfd
, struct filename
*name
,
2044 unsigned int flags
, struct nameidata
*nd
)
2047 struct nameidata
*saved_nd
= set_nameidata(nd
);
2049 retval
= path_lookupat(dfd
, name
, flags
| LOOKUP_RCU
, nd
);
2050 if (unlikely(retval
== -ECHILD
))
2051 retval
= path_lookupat(dfd
, name
, flags
, nd
);
2052 if (unlikely(retval
== -ESTALE
))
2053 retval
= path_lookupat(dfd
, name
, flags
| LOOKUP_REVAL
, nd
);
2055 if (likely(!retval
))
2056 audit_inode(name
, nd
->path
.dentry
, flags
& LOOKUP_PARENT
);
2057 restore_nameidata(saved_nd
);
2061 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2062 static int path_parentat(int dfd
, const struct filename
*name
,
2063 unsigned int flags
, struct nameidata
*nd
)
2065 const char *s
= path_init(dfd
, name
, flags
, nd
);
2069 err
= link_path_walk(s
, nd
);
2071 err
= complete_walk(nd
);
2076 static int filename_parentat(int dfd
, struct filename
*name
,
2077 unsigned int flags
, struct nameidata
*nd
)
2080 struct nameidata
*saved_nd
= set_nameidata(nd
);
2082 retval
= path_parentat(dfd
, name
, flags
| LOOKUP_RCU
, nd
);
2083 if (unlikely(retval
== -ECHILD
))
2084 retval
= path_parentat(dfd
, name
, flags
, nd
);
2085 if (unlikely(retval
== -ESTALE
))
2086 retval
= path_parentat(dfd
, name
, flags
| LOOKUP_REVAL
, nd
);
2088 if (likely(!retval
))
2089 audit_inode(name
, nd
->path
.dentry
, LOOKUP_PARENT
);
2090 restore_nameidata(saved_nd
);
2094 /* does lookup, returns the object with parent locked */
2095 struct dentry
*kern_path_locked(const char *name
, struct path
*path
)
2097 struct filename
*filename
= getname_kernel(name
);
2098 struct nameidata nd
;
2102 if (IS_ERR(filename
))
2103 return ERR_CAST(filename
);
2105 err
= filename_parentat(AT_FDCWD
, filename
, 0, &nd
);
2110 if (nd
.last_type
!= LAST_NORM
) {
2112 d
= ERR_PTR(-EINVAL
);
2115 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2116 d
= __lookup_hash(&nd
.last
, nd
.path
.dentry
, 0);
2118 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2128 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
2130 struct nameidata nd
;
2131 struct filename
*filename
= getname_kernel(name
);
2132 int res
= PTR_ERR(filename
);
2134 if (!IS_ERR(filename
)) {
2135 res
= filename_lookup(AT_FDCWD
, filename
, flags
, &nd
);
2142 EXPORT_SYMBOL(kern_path
);
2145 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2146 * @dentry: pointer to dentry of the base directory
2147 * @mnt: pointer to vfs mount of the base directory
2148 * @name: pointer to file name
2149 * @flags: lookup flags
2150 * @path: pointer to struct path to fill
2152 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
2153 const char *name
, unsigned int flags
,
2156 struct filename
*filename
= getname_kernel(name
);
2157 int err
= PTR_ERR(filename
);
2159 BUG_ON(flags
& LOOKUP_PARENT
);
2161 /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */
2162 if (!IS_ERR(filename
)) {
2163 struct nameidata nd
;
2164 nd
.root
.dentry
= dentry
;
2166 err
= filename_lookup(AT_FDCWD
, filename
,
2167 flags
| LOOKUP_ROOT
, &nd
);
2174 EXPORT_SYMBOL(vfs_path_lookup
);
2177 * lookup_one_len - filesystem helper to lookup single pathname component
2178 * @name: pathname component to lookup
2179 * @base: base directory to lookup from
2180 * @len: maximum length @len should be interpreted to
2182 * Note that this routine is purely a helper for filesystem usage and should
2183 * not be called by generic code.
2185 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2191 WARN_ON_ONCE(!mutex_is_locked(&base
->d_inode
->i_mutex
));
2195 this.hash
= full_name_hash(name
, len
);
2197 return ERR_PTR(-EACCES
);
2199 if (unlikely(name
[0] == '.')) {
2200 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2201 return ERR_PTR(-EACCES
);
2205 c
= *(const unsigned char *)name
++;
2206 if (c
== '/' || c
== '\0')
2207 return ERR_PTR(-EACCES
);
2210 * See if the low-level filesystem might want
2211 * to use its own hash..
2213 if (base
->d_flags
& DCACHE_OP_HASH
) {
2214 int err
= base
->d_op
->d_hash(base
, &this);
2216 return ERR_PTR(err
);
2219 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
2221 return ERR_PTR(err
);
2223 return __lookup_hash(&this, base
, 0);
2225 EXPORT_SYMBOL(lookup_one_len
);
2227 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
2228 struct path
*path
, int *empty
)
2230 struct nameidata nd
;
2231 struct filename
*tmp
= getname_flags(name
, flags
, empty
);
2232 int err
= PTR_ERR(tmp
);
2235 BUG_ON(flags
& LOOKUP_PARENT
);
2237 err
= filename_lookup(dfd
, tmp
, flags
, &nd
);
2245 int user_path_at(int dfd
, const char __user
*name
, unsigned flags
,
2248 return user_path_at_empty(dfd
, name
, flags
, path
, NULL
);
2250 EXPORT_SYMBOL(user_path_at
);
2253 * NB: most callers don't do anything directly with the reference to the
2254 * to struct filename, but the nd->last pointer points into the name string
2255 * allocated by getname. So we must hold the reference to it until all
2256 * path-walking is complete.
2258 static struct filename
*
2259 user_path_parent(int dfd
, const char __user
*path
,
2260 struct path
*parent
,
2265 struct nameidata nd
;
2266 struct filename
*s
= getname(path
);
2269 /* only LOOKUP_REVAL is allowed in extra flags */
2270 flags
&= LOOKUP_REVAL
;
2275 error
= filename_parentat(dfd
, s
, flags
, &nd
);
2278 return ERR_PTR(error
);
2282 *type
= nd
.last_type
;
2288 * mountpoint_last - look up last component for umount
2289 * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
2290 * @path: pointer to container for result
2292 * This is a special lookup_last function just for umount. In this case, we
2293 * need to resolve the path without doing any revalidation.
2295 * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
2296 * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
2297 * in almost all cases, this lookup will be served out of the dcache. The only
2298 * cases where it won't are if nd->last refers to a symlink or the path is
2299 * bogus and it doesn't exist.
2302 * -error: if there was an error during lookup. This includes -ENOENT if the
2303 * lookup found a negative dentry. The nd->path reference will also be
2306 * 0: if we successfully resolved nd->path and found it to not to be a
2307 * symlink that needs to be followed. "path" will also be populated.
2308 * The nd->path reference will also be put.
2310 * 1: if we successfully resolved nd->last and found it to be a symlink
2311 * that needs to be followed. "path" will be populated with the path
2312 * to the link, and nd->path will *not* be put.
2315 mountpoint_last(struct nameidata
*nd
, struct path
*path
)
2318 struct dentry
*dentry
;
2319 struct dentry
*dir
= nd
->path
.dentry
;
2321 /* If we're in rcuwalk, drop out of it to handle last component */
2322 if (nd
->flags
& LOOKUP_RCU
) {
2323 if (unlazy_walk(nd
, NULL
)) {
2329 nd
->flags
&= ~LOOKUP_PARENT
;
2331 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
2332 error
= handle_dots(nd
, nd
->last_type
);
2335 dentry
= dget(nd
->path
.dentry
);
2339 mutex_lock(&dir
->d_inode
->i_mutex
);
2340 dentry
= d_lookup(dir
, &nd
->last
);
2343 * No cached dentry. Mounted dentries are pinned in the cache,
2344 * so that means that this dentry is probably a symlink or the
2345 * path doesn't actually point to a mounted dentry.
2347 dentry
= d_alloc(dir
, &nd
->last
);
2350 mutex_unlock(&dir
->d_inode
->i_mutex
);
2353 dentry
= lookup_real(dir
->d_inode
, dentry
, nd
->flags
);
2354 error
= PTR_ERR(dentry
);
2355 if (IS_ERR(dentry
)) {
2356 mutex_unlock(&dir
->d_inode
->i_mutex
);
2360 mutex_unlock(&dir
->d_inode
->i_mutex
);
2363 if (d_is_negative(dentry
)) {
2370 path
->dentry
= dentry
;
2371 path
->mnt
= nd
->path
.mnt
;
2372 error
= should_follow_link(nd
, path
, nd
->flags
& LOOKUP_FOLLOW
);
2373 if (unlikely(error
)) {
2387 * path_mountpoint - look up a path to be umounted
2388 * @dfd: directory file descriptor to start walk from
2389 * @name: full pathname to walk
2390 * @path: pointer to container for result
2391 * @flags: lookup flags
2393 * Look up the given name, but don't attempt to revalidate the last component.
2394 * Returns 0 and "path" will be valid on success; Returns error otherwise.
2397 path_mountpoint(int dfd
, const struct filename
*name
, struct path
*path
,
2398 struct nameidata
*nd
, unsigned int flags
)
2400 const char *s
= path_init(dfd
, name
, flags
, nd
);
2404 err
= link_path_walk(s
, nd
);
2408 while ((err
= mountpoint_last(nd
, path
)) > 0) {
2409 err
= trailing_symlink(nd
);
2419 filename_mountpoint(int dfd
, struct filename
*name
, struct path
*path
,
2422 struct nameidata nd
, *saved
;
2425 return PTR_ERR(name
);
2426 saved
= set_nameidata(&nd
);
2427 error
= path_mountpoint(dfd
, name
, path
, &nd
, flags
| LOOKUP_RCU
);
2428 if (unlikely(error
== -ECHILD
))
2429 error
= path_mountpoint(dfd
, name
, path
, &nd
, flags
);
2430 if (unlikely(error
== -ESTALE
))
2431 error
= path_mountpoint(dfd
, name
, path
, &nd
, flags
| LOOKUP_REVAL
);
2433 audit_inode(name
, path
->dentry
, 0);
2434 restore_nameidata(saved
);
2440 * user_path_mountpoint_at - lookup a path from userland in order to umount it
2441 * @dfd: directory file descriptor
2442 * @name: pathname from userland
2443 * @flags: lookup flags
2444 * @path: pointer to container to hold result
2446 * A umount is a special case for path walking. We're not actually interested
2447 * in the inode in this situation, and ESTALE errors can be a problem. We
2448 * simply want track down the dentry and vfsmount attached at the mountpoint
2449 * and avoid revalidating the last component.
2451 * Returns 0 and populates "path" on success.
2454 user_path_mountpoint_at(int dfd
, const char __user
*name
, unsigned int flags
,
2457 return filename_mountpoint(dfd
, getname(name
), path
, flags
);
2461 kern_path_mountpoint(int dfd
, const char *name
, struct path
*path
,
2464 return filename_mountpoint(dfd
, getname_kernel(name
), path
, flags
);
2466 EXPORT_SYMBOL(kern_path_mountpoint
);
2468 int __check_sticky(struct inode
*dir
, struct inode
*inode
)
2470 kuid_t fsuid
= current_fsuid();
2472 if (uid_eq(inode
->i_uid
, fsuid
))
2474 if (uid_eq(dir
->i_uid
, fsuid
))
2476 return !capable_wrt_inode_uidgid(inode
, CAP_FOWNER
);
2478 EXPORT_SYMBOL(__check_sticky
);
2481 * Check whether we can remove a link victim from directory dir, check
2482 * whether the type of victim is right.
2483 * 1. We can't do it if dir is read-only (done in permission())
2484 * 2. We should have write and exec permissions on dir
2485 * 3. We can't remove anything from append-only dir
2486 * 4. We can't do anything with immutable dir (done in permission())
2487 * 5. If the sticky bit on dir is set we should either
2488 * a. be owner of dir, or
2489 * b. be owner of victim, or
2490 * c. have CAP_FOWNER capability
2491 * 6. If the victim is append-only or immutable we can't do antyhing with
2492 * links pointing to it.
2493 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2494 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2495 * 9. We can't remove a root or mountpoint.
2496 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
2497 * nfs_async_unlink().
2499 static int may_delete(struct inode
*dir
, struct dentry
*victim
, bool isdir
)
2501 struct inode
*inode
= victim
->d_inode
;
2504 if (d_is_negative(victim
))
2508 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
2509 audit_inode_child(dir
, victim
, AUDIT_TYPE_CHILD_DELETE
);
2511 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2517 if (check_sticky(dir
, inode
) || IS_APPEND(inode
) ||
2518 IS_IMMUTABLE(inode
) || IS_SWAPFILE(inode
))
2521 if (!d_is_dir(victim
))
2523 if (IS_ROOT(victim
))
2525 } else if (d_is_dir(victim
))
2527 if (IS_DEADDIR(dir
))
2529 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2534 /* Check whether we can create an object with dentry child in directory
2536 * 1. We can't do it if child already exists (open has special treatment for
2537 * this case, but since we are inlined it's OK)
2538 * 2. We can't do it if dir is read-only (done in permission())
2539 * 3. We should have write and exec permissions on dir
2540 * 4. We can't do it if dir is immutable (done in permission())
2542 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
2544 audit_inode_child(dir
, child
, AUDIT_TYPE_CHILD_CREATE
);
2547 if (IS_DEADDIR(dir
))
2549 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2553 * p1 and p2 should be directories on the same fs.
2555 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2560 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2564 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2566 p
= d_ancestor(p2
, p1
);
2568 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2569 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2573 p
= d_ancestor(p1
, p2
);
2575 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2576 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2580 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2581 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT2
);
2584 EXPORT_SYMBOL(lock_rename
);
2586 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
2588 mutex_unlock(&p1
->d_inode
->i_mutex
);
2590 mutex_unlock(&p2
->d_inode
->i_mutex
);
2591 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2594 EXPORT_SYMBOL(unlock_rename
);
2596 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
2599 int error
= may_create(dir
, dentry
);
2603 if (!dir
->i_op
->create
)
2604 return -EACCES
; /* shouldn't it be ENOSYS? */
2607 error
= security_inode_create(dir
, dentry
, mode
);
2610 error
= dir
->i_op
->create(dir
, dentry
, mode
, want_excl
);
2612 fsnotify_create(dir
, dentry
);
2615 EXPORT_SYMBOL(vfs_create
);
2617 static int may_open(struct path
*path
, int acc_mode
, int flag
)
2619 struct dentry
*dentry
= path
->dentry
;
2620 struct inode
*inode
= dentry
->d_inode
;
2630 switch (inode
->i_mode
& S_IFMT
) {
2634 if (acc_mode
& MAY_WRITE
)
2639 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
2648 error
= inode_permission(inode
, acc_mode
);
2653 * An append-only file must be opened in append mode for writing.
2655 if (IS_APPEND(inode
)) {
2656 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
2662 /* O_NOATIME can only be set by the owner or superuser */
2663 if (flag
& O_NOATIME
&& !inode_owner_or_capable(inode
))
2669 static int handle_truncate(struct file
*filp
)
2671 struct path
*path
= &filp
->f_path
;
2672 struct inode
*inode
= path
->dentry
->d_inode
;
2673 int error
= get_write_access(inode
);
2677 * Refuse to truncate files with mandatory locks held on them.
2679 error
= locks_verify_locked(filp
);
2681 error
= security_path_truncate(path
);
2683 error
= do_truncate(path
->dentry
, 0,
2684 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
2687 put_write_access(inode
);
2691 static inline int open_to_namei_flags(int flag
)
2693 if ((flag
& O_ACCMODE
) == 3)
2698 static int may_o_create(struct path
*dir
, struct dentry
*dentry
, umode_t mode
)
2700 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
2704 error
= inode_permission(dir
->dentry
->d_inode
, MAY_WRITE
| MAY_EXEC
);
2708 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
2712 * Attempt to atomically look up, create and open a file from a negative
2715 * Returns 0 if successful. The file will have been created and attached to
2716 * @file by the filesystem calling finish_open().
2718 * Returns 1 if the file was looked up only or didn't need creating. The
2719 * caller will need to perform the open themselves. @path will have been
2720 * updated to point to the new dentry. This may be negative.
2722 * Returns an error code otherwise.
2724 static int atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
2725 struct path
*path
, struct file
*file
,
2726 const struct open_flags
*op
,
2727 bool got_write
, bool need_lookup
,
2730 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
2731 unsigned open_flag
= open_to_namei_flags(op
->open_flag
);
2735 int create_error
= 0;
2736 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
2739 BUG_ON(dentry
->d_inode
);
2741 /* Don't create child dentry for a dead directory. */
2742 if (unlikely(IS_DEADDIR(dir
))) {
2748 if ((open_flag
& O_CREAT
) && !IS_POSIXACL(dir
))
2749 mode
&= ~current_umask();
2751 excl
= (open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
);
2753 open_flag
&= ~O_TRUNC
;
2756 * Checking write permission is tricky, bacuse we don't know if we are
2757 * going to actually need it: O_CREAT opens should work as long as the
2758 * file exists. But checking existence breaks atomicity. The trick is
2759 * to check access and if not granted clear O_CREAT from the flags.
2761 * Another problem is returing the "right" error value (e.g. for an
2762 * O_EXCL open we want to return EEXIST not EROFS).
2764 if (((open_flag
& (O_CREAT
| O_TRUNC
)) ||
2765 (open_flag
& O_ACCMODE
) != O_RDONLY
) && unlikely(!got_write
)) {
2766 if (!(open_flag
& O_CREAT
)) {
2768 * No O_CREATE -> atomicity not a requirement -> fall
2769 * back to lookup + open
2772 } else if (open_flag
& (O_EXCL
| O_TRUNC
)) {
2773 /* Fall back and fail with the right error */
2774 create_error
= -EROFS
;
2777 /* No side effects, safe to clear O_CREAT */
2778 create_error
= -EROFS
;
2779 open_flag
&= ~O_CREAT
;
2783 if (open_flag
& O_CREAT
) {
2784 error
= may_o_create(&nd
->path
, dentry
, mode
);
2786 create_error
= error
;
2787 if (open_flag
& O_EXCL
)
2789 open_flag
&= ~O_CREAT
;
2793 if (nd
->flags
& LOOKUP_DIRECTORY
)
2794 open_flag
|= O_DIRECTORY
;
2796 file
->f_path
.dentry
= DENTRY_NOT_SET
;
2797 file
->f_path
.mnt
= nd
->path
.mnt
;
2798 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
, open_flag
, mode
,
2801 if (create_error
&& error
== -ENOENT
)
2802 error
= create_error
;
2806 if (error
) { /* returned 1, that is */
2807 if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
2811 if (file
->f_path
.dentry
) {
2813 dentry
= file
->f_path
.dentry
;
2815 if (*opened
& FILE_CREATED
)
2816 fsnotify_create(dir
, dentry
);
2817 if (!dentry
->d_inode
) {
2818 WARN_ON(*opened
& FILE_CREATED
);
2820 error
= create_error
;
2824 if (excl
&& !(*opened
& FILE_CREATED
)) {
2833 * We didn't have the inode before the open, so check open permission
2836 acc_mode
= op
->acc_mode
;
2837 if (*opened
& FILE_CREATED
) {
2838 WARN_ON(!(open_flag
& O_CREAT
));
2839 fsnotify_create(dir
, dentry
);
2840 acc_mode
= MAY_OPEN
;
2842 error
= may_open(&file
->f_path
, acc_mode
, open_flag
);
2852 dentry
= lookup_real(dir
, dentry
, nd
->flags
);
2854 return PTR_ERR(dentry
);
2857 int open_flag
= op
->open_flag
;
2859 error
= create_error
;
2860 if ((open_flag
& O_EXCL
)) {
2861 if (!dentry
->d_inode
)
2863 } else if (!dentry
->d_inode
) {
2865 } else if ((open_flag
& O_TRUNC
) &&
2869 /* will fail later, go on to get the right error */
2873 path
->dentry
= dentry
;
2874 path
->mnt
= nd
->path
.mnt
;
2879 * Look up and maybe create and open the last component.
2881 * Must be called with i_mutex held on parent.
2883 * Returns 0 if the file was successfully atomically created (if necessary) and
2884 * opened. In this case the file will be returned attached to @file.
2886 * Returns 1 if the file was not completely opened at this time, though lookups
2887 * and creations will have been performed and the dentry returned in @path will
2888 * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
2889 * specified then a negative dentry may be returned.
2891 * An error code is returned otherwise.
2893 * FILE_CREATE will be set in @*opened if the dentry was created and will be
2894 * cleared otherwise prior to returning.
2896 static int lookup_open(struct nameidata
*nd
, struct path
*path
,
2898 const struct open_flags
*op
,
2899 bool got_write
, int *opened
)
2901 struct dentry
*dir
= nd
->path
.dentry
;
2902 struct inode
*dir_inode
= dir
->d_inode
;
2903 struct dentry
*dentry
;
2907 *opened
&= ~FILE_CREATED
;
2908 dentry
= lookup_dcache(&nd
->last
, dir
, nd
->flags
, &need_lookup
);
2910 return PTR_ERR(dentry
);
2912 /* Cached positive dentry: will open in f_op->open */
2913 if (!need_lookup
&& dentry
->d_inode
)
2916 if ((nd
->flags
& LOOKUP_OPEN
) && dir_inode
->i_op
->atomic_open
) {
2917 return atomic_open(nd
, dentry
, path
, file
, op
, got_write
,
2918 need_lookup
, opened
);
2922 BUG_ON(dentry
->d_inode
);
2924 dentry
= lookup_real(dir_inode
, dentry
, nd
->flags
);
2926 return PTR_ERR(dentry
);
2929 /* Negative dentry, just create the file */
2930 if (!dentry
->d_inode
&& (op
->open_flag
& O_CREAT
)) {
2931 umode_t mode
= op
->mode
;
2932 if (!IS_POSIXACL(dir
->d_inode
))
2933 mode
&= ~current_umask();
2935 * This write is needed to ensure that a
2936 * rw->ro transition does not occur between
2937 * the time when the file is created and when
2938 * a permanent write count is taken through
2939 * the 'struct file' in finish_open().
2945 *opened
|= FILE_CREATED
;
2946 error
= security_path_mknod(&nd
->path
, dentry
, mode
, 0);
2949 error
= vfs_create(dir
->d_inode
, dentry
, mode
,
2950 nd
->flags
& LOOKUP_EXCL
);
2955 path
->dentry
= dentry
;
2956 path
->mnt
= nd
->path
.mnt
;
2965 * Handle the last step of open()
2967 static int do_last(struct nameidata
*nd
,
2968 struct file
*file
, const struct open_flags
*op
,
2969 int *opened
, struct filename
*name
)
2971 struct dentry
*dir
= nd
->path
.dentry
;
2972 int open_flag
= op
->open_flag
;
2973 bool will_truncate
= (open_flag
& O_TRUNC
) != 0;
2974 bool got_write
= false;
2975 int acc_mode
= op
->acc_mode
;
2976 struct inode
*inode
;
2977 struct path save_parent
= { .dentry
= NULL
, .mnt
= NULL
};
2979 bool retried
= false;
2982 nd
->flags
&= ~LOOKUP_PARENT
;
2983 nd
->flags
|= op
->intent
;
2985 if (nd
->last_type
!= LAST_NORM
) {
2986 error
= handle_dots(nd
, nd
->last_type
);
2987 if (unlikely(error
)) {
2994 if (!(open_flag
& O_CREAT
)) {
2995 if (nd
->last
.name
[nd
->last
.len
])
2996 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2997 /* we _can_ be in RCU mode here */
2998 error
= lookup_fast(nd
, &path
, &inode
);
3005 BUG_ON(nd
->inode
!= dir
->d_inode
);
3007 /* create side of things */
3009 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
3010 * has been cleared when we got to the last component we are
3013 error
= complete_walk(nd
);
3017 audit_inode(name
, dir
, LOOKUP_PARENT
);
3019 /* trailing slashes? */
3020 if (nd
->last
.name
[nd
->last
.len
])
3025 if (op
->open_flag
& (O_CREAT
| O_TRUNC
| O_WRONLY
| O_RDWR
)) {
3026 error
= mnt_want_write(nd
->path
.mnt
);
3030 * do _not_ fail yet - we might not need that or fail with
3031 * a different error; let lookup_open() decide; we'll be
3032 * dropping this one anyway.
3035 mutex_lock(&dir
->d_inode
->i_mutex
);
3036 error
= lookup_open(nd
, &path
, file
, op
, got_write
, opened
);
3037 mutex_unlock(&dir
->d_inode
->i_mutex
);
3043 if ((*opened
& FILE_CREATED
) ||
3044 !S_ISREG(file_inode(file
)->i_mode
))
3045 will_truncate
= false;
3047 audit_inode(name
, file
->f_path
.dentry
, 0);
3051 if (*opened
& FILE_CREATED
) {
3052 /* Don't check for write permission, don't truncate */
3053 open_flag
&= ~O_TRUNC
;
3054 will_truncate
= false;
3055 acc_mode
= MAY_OPEN
;
3056 path_to_nameidata(&path
, nd
);
3057 goto finish_open_created
;
3061 * create/update audit record if it already exists.
3063 if (d_is_positive(path
.dentry
))
3064 audit_inode(name
, path
.dentry
, 0);
3067 * If atomic_open() acquired write access it is dropped now due to
3068 * possible mount and symlink following (this might be optimized away if
3072 mnt_drop_write(nd
->path
.mnt
);
3077 if ((open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
))
3080 error
= follow_managed(&path
, nd
);
3084 BUG_ON(nd
->flags
& LOOKUP_RCU
);
3085 inode
= path
.dentry
->d_inode
;
3087 if (d_is_negative(path
.dentry
)) {
3088 path_to_nameidata(&path
, nd
);
3094 error
= should_follow_link(nd
, &path
, nd
->flags
& LOOKUP_FOLLOW
);
3095 if (unlikely(error
)) {
3101 if (unlikely(d_is_symlink(path
.dentry
)) && !(open_flag
& O_PATH
)) {
3102 path_to_nameidata(&path
, nd
);
3107 if ((nd
->flags
& LOOKUP_RCU
) || nd
->path
.mnt
!= path
.mnt
) {
3108 path_to_nameidata(&path
, nd
);
3110 save_parent
.dentry
= nd
->path
.dentry
;
3111 save_parent
.mnt
= mntget(path
.mnt
);
3112 nd
->path
.dentry
= path
.dentry
;
3116 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
3118 error
= complete_walk(nd
);
3120 path_put(&save_parent
);
3123 audit_inode(name
, nd
->path
.dentry
, 0);
3125 if ((open_flag
& O_CREAT
) && d_is_dir(nd
->path
.dentry
))
3128 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !d_can_lookup(nd
->path
.dentry
))
3130 if (!d_is_reg(nd
->path
.dentry
))
3131 will_truncate
= false;
3133 if (will_truncate
) {
3134 error
= mnt_want_write(nd
->path
.mnt
);
3139 finish_open_created
:
3140 error
= may_open(&nd
->path
, acc_mode
, open_flag
);
3144 BUG_ON(*opened
& FILE_OPENED
); /* once it's opened, it's opened */
3145 error
= vfs_open(&nd
->path
, file
, current_cred());
3147 *opened
|= FILE_OPENED
;
3149 if (error
== -EOPENSTALE
)
3154 error
= open_check_o_direct(file
);
3157 error
= ima_file_check(file
, op
->acc_mode
, *opened
);
3161 if (will_truncate
) {
3162 error
= handle_truncate(file
);
3168 mnt_drop_write(nd
->path
.mnt
);
3169 path_put(&save_parent
);
3174 path_put_conditional(&path
, nd
);
3181 /* If no saved parent or already retried then can't retry */
3182 if (!save_parent
.dentry
|| retried
)
3185 BUG_ON(save_parent
.dentry
!= dir
);
3186 path_put(&nd
->path
);
3187 nd
->path
= save_parent
;
3188 nd
->inode
= dir
->d_inode
;
3189 save_parent
.mnt
= NULL
;
3190 save_parent
.dentry
= NULL
;
3192 mnt_drop_write(nd
->path
.mnt
);
3199 static int do_tmpfile(int dfd
, struct filename
*pathname
,
3200 struct nameidata
*nd
, int flags
,
3201 const struct open_flags
*op
,
3202 struct file
*file
, int *opened
)
3204 static const struct qstr name
= QSTR_INIT("/", 1);
3205 struct dentry
*dentry
, *child
;
3207 int error
= path_lookupat(dfd
, pathname
,
3208 flags
| LOOKUP_DIRECTORY
, nd
);
3209 if (unlikely(error
))
3211 error
= mnt_want_write(nd
->path
.mnt
);
3212 if (unlikely(error
))
3214 /* we want directory to be writable */
3215 error
= inode_permission(nd
->inode
, MAY_WRITE
| MAY_EXEC
);
3218 dentry
= nd
->path
.dentry
;
3219 dir
= dentry
->d_inode
;
3220 if (!dir
->i_op
->tmpfile
) {
3221 error
= -EOPNOTSUPP
;
3224 child
= d_alloc(dentry
, &name
);
3225 if (unlikely(!child
)) {
3229 nd
->flags
&= ~LOOKUP_DIRECTORY
;
3230 nd
->flags
|= op
->intent
;
3231 dput(nd
->path
.dentry
);
3232 nd
->path
.dentry
= child
;
3233 error
= dir
->i_op
->tmpfile(dir
, nd
->path
.dentry
, op
->mode
);
3236 audit_inode(pathname
, nd
->path
.dentry
, 0);
3237 /* Don't check for other permissions, the inode was just created */
3238 error
= may_open(&nd
->path
, MAY_OPEN
, op
->open_flag
);
3241 file
->f_path
.mnt
= nd
->path
.mnt
;
3242 error
= finish_open(file
, nd
->path
.dentry
, NULL
, opened
);
3245 error
= open_check_o_direct(file
);
3248 } else if (!(op
->open_flag
& O_EXCL
)) {
3249 struct inode
*inode
= file_inode(file
);
3250 spin_lock(&inode
->i_lock
);
3251 inode
->i_state
|= I_LINKABLE
;
3252 spin_unlock(&inode
->i_lock
);
3255 mnt_drop_write(nd
->path
.mnt
);
3257 path_put(&nd
->path
);
3261 static struct file
*path_openat(int dfd
, struct filename
*pathname
,
3262 struct nameidata
*nd
, const struct open_flags
*op
, int flags
)
3269 file
= get_empty_filp();
3273 file
->f_flags
= op
->open_flag
;
3275 if (unlikely(file
->f_flags
& __O_TMPFILE
)) {
3276 error
= do_tmpfile(dfd
, pathname
, nd
, flags
, op
, file
, &opened
);
3280 s
= path_init(dfd
, pathname
, flags
, nd
);
3285 error
= link_path_walk(s
, nd
);
3286 if (unlikely(error
))
3289 while ((error
= do_last(nd
, file
, op
, &opened
, pathname
)) > 0) {
3290 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
3291 error
= trailing_symlink(nd
);
3292 if (unlikely(error
))
3298 if (!(opened
& FILE_OPENED
)) {
3302 if (unlikely(error
)) {
3303 if (error
== -EOPENSTALE
) {
3304 if (flags
& LOOKUP_RCU
)
3309 file
= ERR_PTR(error
);
3314 struct file
*do_filp_open(int dfd
, struct filename
*pathname
,
3315 const struct open_flags
*op
)
3317 struct nameidata nd
, *saved_nd
= set_nameidata(&nd
);
3318 int flags
= op
->lookup_flags
;
3321 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
| LOOKUP_RCU
);
3322 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
3323 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
);
3324 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
3325 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
| LOOKUP_REVAL
);
3326 restore_nameidata(saved_nd
);
3330 struct file
*do_file_open_root(struct dentry
*dentry
, struct vfsmount
*mnt
,
3331 const char *name
, const struct open_flags
*op
)
3333 struct nameidata nd
, *saved_nd
;
3335 struct filename
*filename
;
3336 int flags
= op
->lookup_flags
| LOOKUP_ROOT
;
3339 nd
.root
.dentry
= dentry
;
3341 if (d_is_symlink(dentry
) && op
->intent
& LOOKUP_OPEN
)
3342 return ERR_PTR(-ELOOP
);
3344 filename
= getname_kernel(name
);
3345 if (unlikely(IS_ERR(filename
)))
3346 return ERR_CAST(filename
);
3348 saved_nd
= set_nameidata(&nd
);
3349 file
= path_openat(-1, filename
, &nd
, op
, flags
| LOOKUP_RCU
);
3350 if (unlikely(file
== ERR_PTR(-ECHILD
)))
3351 file
= path_openat(-1, filename
, &nd
, op
, flags
);
3352 if (unlikely(file
== ERR_PTR(-ESTALE
)))
3353 file
= path_openat(-1, filename
, &nd
, op
, flags
| LOOKUP_REVAL
);
3354 restore_nameidata(saved_nd
);
3359 static struct dentry
*filename_create(int dfd
, struct filename
*name
,
3360 struct path
*path
, unsigned int lookup_flags
)
3362 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
3363 struct nameidata nd
;
3366 bool is_dir
= (lookup_flags
& LOOKUP_DIRECTORY
);
3369 * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
3370 * other flags passed in are ignored!
3372 lookup_flags
&= LOOKUP_REVAL
;
3374 error
= filename_parentat(dfd
, name
, lookup_flags
, &nd
);
3376 return ERR_PTR(error
);
3379 * Yucky last component or no last component at all?
3380 * (foo/., foo/.., /////)
3382 if (nd
.last_type
!= LAST_NORM
)
3384 nd
.flags
&= ~LOOKUP_PARENT
;
3385 nd
.flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
3387 /* don't fail immediately if it's r/o, at least try to report other errors */
3388 err2
= mnt_want_write(nd
.path
.mnt
);
3390 * Do the final lookup.
3392 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3393 dentry
= __lookup_hash(&nd
.last
, nd
.path
.dentry
, nd
.flags
);
3398 if (d_is_positive(dentry
))
3402 * Special case - lookup gave negative, but... we had foo/bar/
3403 * From the vfs_mknod() POV we just have a negative dentry -
3404 * all is fine. Let's be bastards - you had / on the end, you've
3405 * been asking for (non-existent) directory. -ENOENT for you.
3407 if (unlikely(!is_dir
&& nd
.last
.name
[nd
.last
.len
])) {
3411 if (unlikely(err2
)) {
3419 dentry
= ERR_PTR(error
);
3421 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
3423 mnt_drop_write(nd
.path
.mnt
);
3429 struct dentry
*kern_path_create(int dfd
, const char *pathname
,
3430 struct path
*path
, unsigned int lookup_flags
)
3432 struct filename
*filename
= getname_kernel(pathname
);
3435 if (IS_ERR(filename
))
3436 return ERR_CAST(filename
);
3437 res
= filename_create(dfd
, filename
, path
, lookup_flags
);
3441 EXPORT_SYMBOL(kern_path_create
);
3443 void done_path_create(struct path
*path
, struct dentry
*dentry
)
3446 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
3447 mnt_drop_write(path
->mnt
);
3450 EXPORT_SYMBOL(done_path_create
);
3452 struct dentry
*user_path_create(int dfd
, const char __user
*pathname
,
3453 struct path
*path
, unsigned int lookup_flags
)
3455 struct filename
*tmp
= getname(pathname
);
3458 return ERR_CAST(tmp
);
3459 res
= filename_create(dfd
, tmp
, path
, lookup_flags
);
3463 EXPORT_SYMBOL(user_path_create
);
3465 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3467 int error
= may_create(dir
, dentry
);
3472 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
3475 if (!dir
->i_op
->mknod
)
3478 error
= devcgroup_inode_mknod(mode
, dev
);
3482 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
3486 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
3488 fsnotify_create(dir
, dentry
);
3491 EXPORT_SYMBOL(vfs_mknod
);
3493 static int may_mknod(umode_t mode
)
3495 switch (mode
& S_IFMT
) {
3501 case 0: /* zero mode translates to S_IFREG */
3510 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
3513 struct dentry
*dentry
;
3516 unsigned int lookup_flags
= 0;
3518 error
= may_mknod(mode
);
3522 dentry
= user_path_create(dfd
, filename
, &path
, lookup_flags
);
3524 return PTR_ERR(dentry
);
3526 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3527 mode
&= ~current_umask();
3528 error
= security_path_mknod(&path
, dentry
, mode
, dev
);
3531 switch (mode
& S_IFMT
) {
3532 case 0: case S_IFREG
:
3533 error
= vfs_create(path
.dentry
->d_inode
,dentry
,mode
,true);
3535 case S_IFCHR
: case S_IFBLK
:
3536 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,
3537 new_decode_dev(dev
));
3539 case S_IFIFO
: case S_IFSOCK
:
3540 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,0);
3544 done_path_create(&path
, dentry
);
3545 if (retry_estale(error
, lookup_flags
)) {
3546 lookup_flags
|= LOOKUP_REVAL
;
3552 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
3554 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
3557 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
3559 int error
= may_create(dir
, dentry
);
3560 unsigned max_links
= dir
->i_sb
->s_max_links
;
3565 if (!dir
->i_op
->mkdir
)
3568 mode
&= (S_IRWXUGO
|S_ISVTX
);
3569 error
= security_inode_mkdir(dir
, dentry
, mode
);
3573 if (max_links
&& dir
->i_nlink
>= max_links
)
3576 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
3578 fsnotify_mkdir(dir
, dentry
);
3581 EXPORT_SYMBOL(vfs_mkdir
);
3583 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, umode_t
, mode
)
3585 struct dentry
*dentry
;
3588 unsigned int lookup_flags
= LOOKUP_DIRECTORY
;
3591 dentry
= user_path_create(dfd
, pathname
, &path
, lookup_flags
);
3593 return PTR_ERR(dentry
);
3595 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3596 mode
&= ~current_umask();
3597 error
= security_path_mkdir(&path
, dentry
, mode
);
3599 error
= vfs_mkdir(path
.dentry
->d_inode
, dentry
, mode
);
3600 done_path_create(&path
, dentry
);
3601 if (retry_estale(error
, lookup_flags
)) {
3602 lookup_flags
|= LOOKUP_REVAL
;
3608 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, umode_t
, mode
)
3610 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
3614 * The dentry_unhash() helper will try to drop the dentry early: we
3615 * should have a usage count of 1 if we're the only user of this
3616 * dentry, and if that is true (possibly after pruning the dcache),
3617 * then we drop the dentry now.
3619 * A low-level filesystem can, if it choses, legally
3622 * if (!d_unhashed(dentry))
3625 * if it cannot handle the case of removing a directory
3626 * that is still in use by something else..
3628 void dentry_unhash(struct dentry
*dentry
)
3630 shrink_dcache_parent(dentry
);
3631 spin_lock(&dentry
->d_lock
);
3632 if (dentry
->d_lockref
.count
== 1)
3634 spin_unlock(&dentry
->d_lock
);
3636 EXPORT_SYMBOL(dentry_unhash
);
3638 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
3640 int error
= may_delete(dir
, dentry
, 1);
3645 if (!dir
->i_op
->rmdir
)
3649 mutex_lock(&dentry
->d_inode
->i_mutex
);
3652 if (is_local_mountpoint(dentry
))
3655 error
= security_inode_rmdir(dir
, dentry
);
3659 shrink_dcache_parent(dentry
);
3660 error
= dir
->i_op
->rmdir(dir
, dentry
);
3664 dentry
->d_inode
->i_flags
|= S_DEAD
;
3666 detach_mounts(dentry
);
3669 mutex_unlock(&dentry
->d_inode
->i_mutex
);
3675 EXPORT_SYMBOL(vfs_rmdir
);
3677 static long do_rmdir(int dfd
, const char __user
*pathname
)
3680 struct filename
*name
;
3681 struct dentry
*dentry
;
3685 unsigned int lookup_flags
= 0;
3687 name
= user_path_parent(dfd
, pathname
,
3688 &path
, &last
, &type
, lookup_flags
);
3690 return PTR_ERR(name
);
3704 error
= mnt_want_write(path
.mnt
);
3708 mutex_lock_nested(&path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3709 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3710 error
= PTR_ERR(dentry
);
3713 if (!dentry
->d_inode
) {
3717 error
= security_path_rmdir(&path
, dentry
);
3720 error
= vfs_rmdir(path
.dentry
->d_inode
, dentry
);
3724 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3725 mnt_drop_write(path
.mnt
);
3729 if (retry_estale(error
, lookup_flags
)) {
3730 lookup_flags
|= LOOKUP_REVAL
;
3736 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
3738 return do_rmdir(AT_FDCWD
, pathname
);
3742 * vfs_unlink - unlink a filesystem object
3743 * @dir: parent directory
3745 * @delegated_inode: returns victim inode, if the inode is delegated.
3747 * The caller must hold dir->i_mutex.
3749 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
3750 * return a reference to the inode in delegated_inode. The caller
3751 * should then break the delegation on that inode and retry. Because
3752 * breaking a delegation may take a long time, the caller should drop
3753 * dir->i_mutex before doing so.
3755 * Alternatively, a caller may pass NULL for delegated_inode. This may
3756 * be appropriate for callers that expect the underlying filesystem not
3757 * to be NFS exported.
3759 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
, struct inode
**delegated_inode
)
3761 struct inode
*target
= dentry
->d_inode
;
3762 int error
= may_delete(dir
, dentry
, 0);
3767 if (!dir
->i_op
->unlink
)
3770 mutex_lock(&target
->i_mutex
);
3771 if (is_local_mountpoint(dentry
))
3774 error
= security_inode_unlink(dir
, dentry
);
3776 error
= try_break_deleg(target
, delegated_inode
);
3779 error
= dir
->i_op
->unlink(dir
, dentry
);
3782 detach_mounts(dentry
);
3787 mutex_unlock(&target
->i_mutex
);
3789 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
3790 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
3791 fsnotify_link_count(target
);
3797 EXPORT_SYMBOL(vfs_unlink
);
3800 * Make sure that the actual truncation of the file will occur outside its
3801 * directory's i_mutex. Truncate can take a long time if there is a lot of
3802 * writeout happening, and we don't want to prevent access to the directory
3803 * while waiting on the I/O.
3805 static long do_unlinkat(int dfd
, const char __user
*pathname
)
3808 struct filename
*name
;
3809 struct dentry
*dentry
;
3813 struct inode
*inode
= NULL
;
3814 struct inode
*delegated_inode
= NULL
;
3815 unsigned int lookup_flags
= 0;
3817 name
= user_path_parent(dfd
, pathname
,
3818 &path
, &last
, &type
, lookup_flags
);
3820 return PTR_ERR(name
);
3823 if (type
!= LAST_NORM
)
3826 error
= mnt_want_write(path
.mnt
);
3830 mutex_lock_nested(&path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3831 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3832 error
= PTR_ERR(dentry
);
3833 if (!IS_ERR(dentry
)) {
3834 /* Why not before? Because we want correct error value */
3835 if (last
.name
[last
.len
])
3837 inode
= dentry
->d_inode
;
3838 if (d_is_negative(dentry
))
3841 error
= security_path_unlink(&path
, dentry
);
3844 error
= vfs_unlink(path
.dentry
->d_inode
, dentry
, &delegated_inode
);
3848 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3850 iput(inode
); /* truncate the inode here */
3852 if (delegated_inode
) {
3853 error
= break_deleg_wait(&delegated_inode
);
3857 mnt_drop_write(path
.mnt
);
3861 if (retry_estale(error
, lookup_flags
)) {
3862 lookup_flags
|= LOOKUP_REVAL
;
3869 if (d_is_negative(dentry
))
3871 else if (d_is_dir(dentry
))
3878 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
3880 if ((flag
& ~AT_REMOVEDIR
) != 0)
3883 if (flag
& AT_REMOVEDIR
)
3884 return do_rmdir(dfd
, pathname
);
3886 return do_unlinkat(dfd
, pathname
);
3889 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
3891 return do_unlinkat(AT_FDCWD
, pathname
);
3894 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
3896 int error
= may_create(dir
, dentry
);
3901 if (!dir
->i_op
->symlink
)
3904 error
= security_inode_symlink(dir
, dentry
, oldname
);
3908 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
3910 fsnotify_create(dir
, dentry
);
3913 EXPORT_SYMBOL(vfs_symlink
);
3915 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
3916 int, newdfd
, const char __user
*, newname
)
3919 struct filename
*from
;
3920 struct dentry
*dentry
;
3922 unsigned int lookup_flags
= 0;
3924 from
= getname(oldname
);
3926 return PTR_ERR(from
);
3928 dentry
= user_path_create(newdfd
, newname
, &path
, lookup_flags
);
3929 error
= PTR_ERR(dentry
);
3933 error
= security_path_symlink(&path
, dentry
, from
->name
);
3935 error
= vfs_symlink(path
.dentry
->d_inode
, dentry
, from
->name
);
3936 done_path_create(&path
, dentry
);
3937 if (retry_estale(error
, lookup_flags
)) {
3938 lookup_flags
|= LOOKUP_REVAL
;
3946 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
3948 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
3952 * vfs_link - create a new link
3953 * @old_dentry: object to be linked
3955 * @new_dentry: where to create the new link
3956 * @delegated_inode: returns inode needing a delegation break
3958 * The caller must hold dir->i_mutex
3960 * If vfs_link discovers a delegation on the to-be-linked file in need
3961 * of breaking, it will return -EWOULDBLOCK and return a reference to the
3962 * inode in delegated_inode. The caller should then break the delegation
3963 * and retry. Because breaking a delegation may take a long time, the
3964 * caller should drop the i_mutex before doing so.
3966 * Alternatively, a caller may pass NULL for delegated_inode. This may
3967 * be appropriate for callers that expect the underlying filesystem not
3968 * to be NFS exported.
3970 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
, struct inode
**delegated_inode
)
3972 struct inode
*inode
= old_dentry
->d_inode
;
3973 unsigned max_links
= dir
->i_sb
->s_max_links
;
3979 error
= may_create(dir
, new_dentry
);
3983 if (dir
->i_sb
!= inode
->i_sb
)
3987 * A link to an append-only or immutable file cannot be created.
3989 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
3991 if (!dir
->i_op
->link
)
3993 if (S_ISDIR(inode
->i_mode
))
3996 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
4000 mutex_lock(&inode
->i_mutex
);
4001 /* Make sure we don't allow creating hardlink to an unlinked file */
4002 if (inode
->i_nlink
== 0 && !(inode
->i_state
& I_LINKABLE
))
4004 else if (max_links
&& inode
->i_nlink
>= max_links
)
4007 error
= try_break_deleg(inode
, delegated_inode
);
4009 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
4012 if (!error
&& (inode
->i_state
& I_LINKABLE
)) {
4013 spin_lock(&inode
->i_lock
);
4014 inode
->i_state
&= ~I_LINKABLE
;
4015 spin_unlock(&inode
->i_lock
);
4017 mutex_unlock(&inode
->i_mutex
);
4019 fsnotify_link(dir
, inode
, new_dentry
);
4022 EXPORT_SYMBOL(vfs_link
);
4025 * Hardlinks are often used in delicate situations. We avoid
4026 * security-related surprises by not following symlinks on the
4029 * We don't follow them on the oldname either to be compatible
4030 * with linux 2.0, and to avoid hard-linking to directories
4031 * and other special files. --ADM
4033 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
4034 int, newdfd
, const char __user
*, newname
, int, flags
)
4036 struct dentry
*new_dentry
;
4037 struct path old_path
, new_path
;
4038 struct inode
*delegated_inode
= NULL
;
4042 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0)
4045 * To use null names we require CAP_DAC_READ_SEARCH
4046 * This ensures that not everyone will be able to create
4047 * handlink using the passed filedescriptor.
4049 if (flags
& AT_EMPTY_PATH
) {
4050 if (!capable(CAP_DAC_READ_SEARCH
))
4055 if (flags
& AT_SYMLINK_FOLLOW
)
4056 how
|= LOOKUP_FOLLOW
;
4058 error
= user_path_at(olddfd
, oldname
, how
, &old_path
);
4062 new_dentry
= user_path_create(newdfd
, newname
, &new_path
,
4063 (how
& LOOKUP_REVAL
));
4064 error
= PTR_ERR(new_dentry
);
4065 if (IS_ERR(new_dentry
))
4069 if (old_path
.mnt
!= new_path
.mnt
)
4071 error
= may_linkat(&old_path
);
4072 if (unlikely(error
))
4074 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
4077 error
= vfs_link(old_path
.dentry
, new_path
.dentry
->d_inode
, new_dentry
, &delegated_inode
);
4079 done_path_create(&new_path
, new_dentry
);
4080 if (delegated_inode
) {
4081 error
= break_deleg_wait(&delegated_inode
);
4083 path_put(&old_path
);
4087 if (retry_estale(error
, how
)) {
4088 path_put(&old_path
);
4089 how
|= LOOKUP_REVAL
;
4093 path_put(&old_path
);
4098 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
4100 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4104 * vfs_rename - rename a filesystem object
4105 * @old_dir: parent of source
4106 * @old_dentry: source
4107 * @new_dir: parent of destination
4108 * @new_dentry: destination
4109 * @delegated_inode: returns an inode needing a delegation break
4110 * @flags: rename flags
4112 * The caller must hold multiple mutexes--see lock_rename()).
4114 * If vfs_rename discovers a delegation in need of breaking at either
4115 * the source or destination, it will return -EWOULDBLOCK and return a
4116 * reference to the inode in delegated_inode. The caller should then
4117 * break the delegation and retry. Because breaking a delegation may
4118 * take a long time, the caller should drop all locks before doing
4121 * Alternatively, a caller may pass NULL for delegated_inode. This may
4122 * be appropriate for callers that expect the underlying filesystem not
4123 * to be NFS exported.
4125 * The worst of all namespace operations - renaming directory. "Perverted"
4126 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4128 * a) we can get into loop creation.
4129 * b) race potential - two innocent renames can create a loop together.
4130 * That's where 4.4 screws up. Current fix: serialization on
4131 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
4133 * c) we have to lock _four_ objects - parents and victim (if it exists),
4134 * and source (if it is not a directory).
4135 * And that - after we got ->i_mutex on parents (until then we don't know
4136 * whether the target exists). Solution: try to be smart with locking
4137 * order for inodes. We rely on the fact that tree topology may change
4138 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
4139 * move will be locked. Thus we can rank directories by the tree
4140 * (ancestors first) and rank all non-directories after them.
4141 * That works since everybody except rename does "lock parent, lookup,
4142 * lock child" and rename is under ->s_vfs_rename_mutex.
4143 * HOWEVER, it relies on the assumption that any object with ->lookup()
4144 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4145 * we'd better make sure that there's no link(2) for them.
4146 * d) conversion from fhandle to dentry may come in the wrong moment - when
4147 * we are removing the target. Solution: we will have to grab ->i_mutex
4148 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
4149 * ->i_mutex on parents, which works but leads to some truly excessive
4152 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
4153 struct inode
*new_dir
, struct dentry
*new_dentry
,
4154 struct inode
**delegated_inode
, unsigned int flags
)
4157 bool is_dir
= d_is_dir(old_dentry
);
4158 const unsigned char *old_name
;
4159 struct inode
*source
= old_dentry
->d_inode
;
4160 struct inode
*target
= new_dentry
->d_inode
;
4161 bool new_is_dir
= false;
4162 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
4164 if (source
== target
)
4167 error
= may_delete(old_dir
, old_dentry
, is_dir
);
4172 error
= may_create(new_dir
, new_dentry
);
4174 new_is_dir
= d_is_dir(new_dentry
);
4176 if (!(flags
& RENAME_EXCHANGE
))
4177 error
= may_delete(new_dir
, new_dentry
, is_dir
);
4179 error
= may_delete(new_dir
, new_dentry
, new_is_dir
);
4184 if (!old_dir
->i_op
->rename
&& !old_dir
->i_op
->rename2
)
4187 if (flags
&& !old_dir
->i_op
->rename2
)
4191 * If we are going to change the parent - check write permissions,
4192 * we'll need to flip '..'.
4194 if (new_dir
!= old_dir
) {
4196 error
= inode_permission(source
, MAY_WRITE
);
4200 if ((flags
& RENAME_EXCHANGE
) && new_is_dir
) {
4201 error
= inode_permission(target
, MAY_WRITE
);
4207 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
,
4212 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
4214 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4215 lock_two_nondirectories(source
, target
);
4217 mutex_lock(&target
->i_mutex
);
4220 if (is_local_mountpoint(old_dentry
) || is_local_mountpoint(new_dentry
))
4223 if (max_links
&& new_dir
!= old_dir
) {
4225 if (is_dir
&& !new_is_dir
&& new_dir
->i_nlink
>= max_links
)
4227 if ((flags
& RENAME_EXCHANGE
) && !is_dir
&& new_is_dir
&&
4228 old_dir
->i_nlink
>= max_links
)
4231 if (is_dir
&& !(flags
& RENAME_EXCHANGE
) && target
)
4232 shrink_dcache_parent(new_dentry
);
4234 error
= try_break_deleg(source
, delegated_inode
);
4238 if (target
&& !new_is_dir
) {
4239 error
= try_break_deleg(target
, delegated_inode
);
4243 if (!old_dir
->i_op
->rename2
) {
4244 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
,
4245 new_dir
, new_dentry
);
4247 WARN_ON(old_dir
->i_op
->rename
!= NULL
);
4248 error
= old_dir
->i_op
->rename2(old_dir
, old_dentry
,
4249 new_dir
, new_dentry
, flags
);
4254 if (!(flags
& RENAME_EXCHANGE
) && target
) {
4256 target
->i_flags
|= S_DEAD
;
4257 dont_mount(new_dentry
);
4258 detach_mounts(new_dentry
);
4260 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
)) {
4261 if (!(flags
& RENAME_EXCHANGE
))
4262 d_move(old_dentry
, new_dentry
);
4264 d_exchange(old_dentry
, new_dentry
);
4267 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4268 unlock_two_nondirectories(source
, target
);
4270 mutex_unlock(&target
->i_mutex
);
4273 fsnotify_move(old_dir
, new_dir
, old_name
, is_dir
,
4274 !(flags
& RENAME_EXCHANGE
) ? target
: NULL
, old_dentry
);
4275 if (flags
& RENAME_EXCHANGE
) {
4276 fsnotify_move(new_dir
, old_dir
, old_dentry
->d_name
.name
,
4277 new_is_dir
, NULL
, new_dentry
);
4280 fsnotify_oldname_free(old_name
);
4284 EXPORT_SYMBOL(vfs_rename
);
4286 SYSCALL_DEFINE5(renameat2
, int, olddfd
, const char __user
*, oldname
,
4287 int, newdfd
, const char __user
*, newname
, unsigned int, flags
)
4289 struct dentry
*old_dentry
, *new_dentry
;
4290 struct dentry
*trap
;
4291 struct path old_path
, new_path
;
4292 struct qstr old_last
, new_last
;
4293 int old_type
, new_type
;
4294 struct inode
*delegated_inode
= NULL
;
4295 struct filename
*from
;
4296 struct filename
*to
;
4297 unsigned int lookup_flags
= 0, target_flags
= LOOKUP_RENAME_TARGET
;
4298 bool should_retry
= false;
4301 if (flags
& ~(RENAME_NOREPLACE
| RENAME_EXCHANGE
| RENAME_WHITEOUT
))
4304 if ((flags
& (RENAME_NOREPLACE
| RENAME_WHITEOUT
)) &&
4305 (flags
& RENAME_EXCHANGE
))
4308 if ((flags
& RENAME_WHITEOUT
) && !capable(CAP_MKNOD
))
4311 if (flags
& RENAME_EXCHANGE
)
4315 from
= user_path_parent(olddfd
, oldname
,
4316 &old_path
, &old_last
, &old_type
, lookup_flags
);
4318 error
= PTR_ERR(from
);
4322 to
= user_path_parent(newdfd
, newname
,
4323 &new_path
, &new_last
, &new_type
, lookup_flags
);
4325 error
= PTR_ERR(to
);
4330 if (old_path
.mnt
!= new_path
.mnt
)
4334 if (old_type
!= LAST_NORM
)
4337 if (flags
& RENAME_NOREPLACE
)
4339 if (new_type
!= LAST_NORM
)
4342 error
= mnt_want_write(old_path
.mnt
);
4347 trap
= lock_rename(new_path
.dentry
, old_path
.dentry
);
4349 old_dentry
= __lookup_hash(&old_last
, old_path
.dentry
, lookup_flags
);
4350 error
= PTR_ERR(old_dentry
);
4351 if (IS_ERR(old_dentry
))
4353 /* source must exist */
4355 if (d_is_negative(old_dentry
))
4357 new_dentry
= __lookup_hash(&new_last
, new_path
.dentry
, lookup_flags
| target_flags
);
4358 error
= PTR_ERR(new_dentry
);
4359 if (IS_ERR(new_dentry
))
4362 if ((flags
& RENAME_NOREPLACE
) && d_is_positive(new_dentry
))
4364 if (flags
& RENAME_EXCHANGE
) {
4366 if (d_is_negative(new_dentry
))
4369 if (!d_is_dir(new_dentry
)) {
4371 if (new_last
.name
[new_last
.len
])
4375 /* unless the source is a directory trailing slashes give -ENOTDIR */
4376 if (!d_is_dir(old_dentry
)) {
4378 if (old_last
.name
[old_last
.len
])
4380 if (!(flags
& RENAME_EXCHANGE
) && new_last
.name
[new_last
.len
])
4383 /* source should not be ancestor of target */
4385 if (old_dentry
== trap
)
4387 /* target should not be an ancestor of source */
4388 if (!(flags
& RENAME_EXCHANGE
))
4390 if (new_dentry
== trap
)
4393 error
= security_path_rename(&old_path
, old_dentry
,
4394 &new_path
, new_dentry
, flags
);
4397 error
= vfs_rename(old_path
.dentry
->d_inode
, old_dentry
,
4398 new_path
.dentry
->d_inode
, new_dentry
,
4399 &delegated_inode
, flags
);
4405 unlock_rename(new_path
.dentry
, old_path
.dentry
);
4406 if (delegated_inode
) {
4407 error
= break_deleg_wait(&delegated_inode
);
4411 mnt_drop_write(old_path
.mnt
);
4413 if (retry_estale(error
, lookup_flags
))
4414 should_retry
= true;
4415 path_put(&new_path
);
4418 path_put(&old_path
);
4421 should_retry
= false;
4422 lookup_flags
|= LOOKUP_REVAL
;
4429 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
4430 int, newdfd
, const char __user
*, newname
)
4432 return sys_renameat2(olddfd
, oldname
, newdfd
, newname
, 0);
4435 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
4437 return sys_renameat2(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4440 int vfs_whiteout(struct inode
*dir
, struct dentry
*dentry
)
4442 int error
= may_create(dir
, dentry
);
4446 if (!dir
->i_op
->mknod
)
4449 return dir
->i_op
->mknod(dir
, dentry
,
4450 S_IFCHR
| WHITEOUT_MODE
, WHITEOUT_DEV
);
4452 EXPORT_SYMBOL(vfs_whiteout
);
4454 int readlink_copy(char __user
*buffer
, int buflen
, const char *link
)
4456 int len
= PTR_ERR(link
);
4461 if (len
> (unsigned) buflen
)
4463 if (copy_to_user(buffer
, link
, len
))
4468 EXPORT_SYMBOL(readlink_copy
);
4471 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
4472 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
4473 * using) it for any given inode is up to filesystem.
4475 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4478 const char *link
= dentry
->d_inode
->i_link
;
4482 link
= dentry
->d_inode
->i_op
->follow_link(dentry
, &cookie
);
4484 return PTR_ERR(link
);
4486 res
= readlink_copy(buffer
, buflen
, link
);
4487 if (dentry
->d_inode
->i_op
->put_link
)
4488 dentry
->d_inode
->i_op
->put_link(dentry
, cookie
);
4491 EXPORT_SYMBOL(generic_readlink
);
4493 /* get the link contents into pagecache */
4494 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
4498 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
4499 page
= read_mapping_page(mapping
, 0, NULL
);
4504 nd_terminate_link(kaddr
, dentry
->d_inode
->i_size
, PAGE_SIZE
- 1);
4508 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4510 struct page
*page
= NULL
;
4511 int res
= readlink_copy(buffer
, buflen
, page_getlink(dentry
, &page
));
4514 page_cache_release(page
);
4518 EXPORT_SYMBOL(page_readlink
);
4520 const char *page_follow_link_light(struct dentry
*dentry
, void **cookie
)
4522 struct page
*page
= NULL
;
4523 char *res
= page_getlink(dentry
, &page
);
4528 EXPORT_SYMBOL(page_follow_link_light
);
4530 void page_put_link(struct dentry
*dentry
, void *cookie
)
4532 struct page
*page
= cookie
;
4534 page_cache_release(page
);
4536 EXPORT_SYMBOL(page_put_link
);
4539 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
4541 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
4543 struct address_space
*mapping
= inode
->i_mapping
;
4548 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
4550 flags
|= AOP_FLAG_NOFS
;
4553 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
4554 flags
, &page
, &fsdata
);
4558 kaddr
= kmap_atomic(page
);
4559 memcpy(kaddr
, symname
, len
-1);
4560 kunmap_atomic(kaddr
);
4562 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
4569 mark_inode_dirty(inode
);
4574 EXPORT_SYMBOL(__page_symlink
);
4576 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
4578 return __page_symlink(inode
, symname
, len
,
4579 !(mapping_gfp_mask(inode
->i_mapping
) & __GFP_FS
));
4581 EXPORT_SYMBOL(page_symlink
);
4583 const struct inode_operations page_symlink_inode_operations
= {
4584 .readlink
= generic_readlink
,
4585 .follow_link
= page_follow_link_light
,
4586 .put_link
= page_put_link
,
4588 EXPORT_SYMBOL(page_symlink_inode_operations
);