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
);
499 struct inode
*inode
; /* path.dentry.d_inode */
505 char *saved_names
[MAX_NESTED_LINKS
+ 1];
509 * Path walking has 2 modes, rcu-walk and ref-walk (see
510 * Documentation/filesystems/path-lookup.txt). In situations when we can't
511 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
512 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
513 * mode. Refcounts are grabbed at the last known good point before rcu-walk
514 * got stuck, so ref-walk may continue from there. If this is not successful
515 * (eg. a seqcount has changed), then failure is returned and it's up to caller
516 * to restart the path walk from the beginning in ref-walk mode.
520 * unlazy_walk - try to switch to ref-walk mode.
521 * @nd: nameidata pathwalk data
522 * @dentry: child of nd->path.dentry or NULL
523 * Returns: 0 on success, -ECHILD on failure
525 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
526 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
527 * @nd or NULL. Must be called from rcu-walk context.
529 static int unlazy_walk(struct nameidata
*nd
, struct dentry
*dentry
)
531 struct fs_struct
*fs
= current
->fs
;
532 struct dentry
*parent
= nd
->path
.dentry
;
534 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
537 * After legitimizing the bastards, terminate_walk()
538 * will do the right thing for non-RCU mode, and all our
539 * subsequent exit cases should rcu_read_unlock()
540 * before returning. Do vfsmount first; if dentry
541 * can't be legitimized, just set nd->path.dentry to NULL
542 * and rely on dput(NULL) being a no-op.
544 if (!legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
))
546 nd
->flags
&= ~LOOKUP_RCU
;
548 if (!lockref_get_not_dead(&parent
->d_lockref
)) {
549 nd
->path
.dentry
= NULL
;
554 * For a negative lookup, the lookup sequence point is the parents
555 * sequence point, and it only needs to revalidate the parent dentry.
557 * For a positive lookup, we need to move both the parent and the
558 * dentry from the RCU domain to be properly refcounted. And the
559 * sequence number in the dentry validates *both* dentry counters,
560 * since we checked the sequence number of the parent after we got
561 * the child sequence number. So we know the parent must still
562 * be valid if the child sequence number is still valid.
565 if (read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
567 BUG_ON(nd
->inode
!= parent
->d_inode
);
569 if (!lockref_get_not_dead(&dentry
->d_lockref
))
571 if (read_seqcount_retry(&dentry
->d_seq
, nd
->seq
))
576 * Sequence counts matched. Now make sure that the root is
577 * still valid and get it if required.
579 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
580 spin_lock(&fs
->lock
);
581 if (nd
->root
.mnt
!= fs
->root
.mnt
|| nd
->root
.dentry
!= fs
->root
.dentry
)
582 goto unlock_and_drop_dentry
;
584 spin_unlock(&fs
->lock
);
590 unlock_and_drop_dentry
:
591 spin_unlock(&fs
->lock
);
599 if (!(nd
->flags
& LOOKUP_ROOT
))
604 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
606 return dentry
->d_op
->d_revalidate(dentry
, flags
);
610 * complete_walk - successful completion of path walk
611 * @nd: pointer nameidata
613 * If we had been in RCU mode, drop out of it and legitimize nd->path.
614 * Revalidate the final result, unless we'd already done that during
615 * the path walk or the filesystem doesn't ask for it. Return 0 on
616 * success, -error on failure. In case of failure caller does not
617 * need to drop nd->path.
619 static int complete_walk(struct nameidata
*nd
)
621 struct dentry
*dentry
= nd
->path
.dentry
;
624 if (nd
->flags
& LOOKUP_RCU
) {
625 nd
->flags
&= ~LOOKUP_RCU
;
626 if (!(nd
->flags
& LOOKUP_ROOT
))
629 if (!legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
)) {
633 if (unlikely(!lockref_get_not_dead(&dentry
->d_lockref
))) {
635 mntput(nd
->path
.mnt
);
638 if (read_seqcount_retry(&dentry
->d_seq
, nd
->seq
)) {
641 mntput(nd
->path
.mnt
);
647 if (likely(!(nd
->flags
& LOOKUP_JUMPED
)))
650 if (likely(!(dentry
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)))
653 status
= dentry
->d_op
->d_weak_revalidate(dentry
, nd
->flags
);
664 static __always_inline
void set_root(struct nameidata
*nd
)
666 get_fs_root(current
->fs
, &nd
->root
);
669 static int link_path_walk(const char *, struct nameidata
*);
671 static __always_inline
unsigned set_root_rcu(struct nameidata
*nd
)
673 struct fs_struct
*fs
= current
->fs
;
677 seq
= read_seqcount_begin(&fs
->seq
);
679 res
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
680 } while (read_seqcount_retry(&fs
->seq
, seq
));
684 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
687 if (path
->mnt
!= nd
->path
.mnt
)
691 static inline void path_to_nameidata(const struct path
*path
,
692 struct nameidata
*nd
)
694 if (!(nd
->flags
& LOOKUP_RCU
)) {
695 dput(nd
->path
.dentry
);
696 if (nd
->path
.mnt
!= path
->mnt
)
697 mntput(nd
->path
.mnt
);
699 nd
->path
.mnt
= path
->mnt
;
700 nd
->path
.dentry
= path
->dentry
;
704 * Helper to directly jump to a known parsed path from ->follow_link,
705 * caller must have taken a reference to path beforehand.
707 void nd_jump_link(struct nameidata
*nd
, struct path
*path
)
712 nd
->inode
= nd
->path
.dentry
->d_inode
;
713 nd
->flags
|= LOOKUP_JUMPED
;
716 void nd_set_link(struct nameidata
*nd
, char *path
)
718 nd
->saved_names
[nd
->depth
] = path
;
720 EXPORT_SYMBOL(nd_set_link
);
722 char *nd_get_link(struct nameidata
*nd
)
724 return nd
->saved_names
[nd
->depth
];
726 EXPORT_SYMBOL(nd_get_link
);
728 static inline void put_link(struct nameidata
*nd
, struct path
*link
, void *cookie
)
730 struct inode
*inode
= link
->dentry
->d_inode
;
731 if (inode
->i_op
->put_link
)
732 inode
->i_op
->put_link(link
->dentry
, nd
, cookie
);
736 int sysctl_protected_symlinks __read_mostly
= 0;
737 int sysctl_protected_hardlinks __read_mostly
= 0;
740 * may_follow_link - Check symlink following for unsafe situations
741 * @link: The path of the symlink
742 * @nd: nameidata pathwalk data
744 * In the case of the sysctl_protected_symlinks sysctl being enabled,
745 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
746 * in a sticky world-writable directory. This is to protect privileged
747 * processes from failing races against path names that may change out
748 * from under them by way of other users creating malicious symlinks.
749 * It will permit symlinks to be followed only when outside a sticky
750 * world-writable directory, or when the uid of the symlink and follower
751 * match, or when the directory owner matches the symlink's owner.
753 * Returns 0 if following the symlink is allowed, -ve on error.
755 static inline int may_follow_link(struct path
*link
, struct nameidata
*nd
)
757 const struct inode
*inode
;
758 const struct inode
*parent
;
760 if (!sysctl_protected_symlinks
)
763 /* Allowed if owner and follower match. */
764 inode
= link
->dentry
->d_inode
;
765 if (uid_eq(current_cred()->fsuid
, inode
->i_uid
))
768 /* Allowed if parent directory not sticky and world-writable. */
769 parent
= nd
->path
.dentry
->d_inode
;
770 if ((parent
->i_mode
& (S_ISVTX
|S_IWOTH
)) != (S_ISVTX
|S_IWOTH
))
773 /* Allowed if parent directory and link owner match. */
774 if (uid_eq(parent
->i_uid
, inode
->i_uid
))
777 audit_log_link_denied("follow_link", link
);
778 path_put_conditional(link
, nd
);
784 * safe_hardlink_source - Check for safe hardlink conditions
785 * @inode: the source inode to hardlink from
787 * Return false if at least one of the following conditions:
788 * - inode is not a regular file
790 * - inode is setgid and group-exec
791 * - access failure for read and write
793 * Otherwise returns true.
795 static bool safe_hardlink_source(struct inode
*inode
)
797 umode_t mode
= inode
->i_mode
;
799 /* Special files should not get pinned to the filesystem. */
803 /* Setuid files should not get pinned to the filesystem. */
807 /* Executable setgid files should not get pinned to the filesystem. */
808 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
))
811 /* Hardlinking to unreadable or unwritable sources is dangerous. */
812 if (inode_permission(inode
, MAY_READ
| MAY_WRITE
))
819 * may_linkat - Check permissions for creating a hardlink
820 * @link: the source to hardlink from
822 * Block hardlink when all of:
823 * - sysctl_protected_hardlinks enabled
824 * - fsuid does not match inode
825 * - hardlink source is unsafe (see safe_hardlink_source() above)
828 * Returns 0 if successful, -ve on error.
830 static int may_linkat(struct path
*link
)
832 const struct cred
*cred
;
835 if (!sysctl_protected_hardlinks
)
838 cred
= current_cred();
839 inode
= link
->dentry
->d_inode
;
841 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
842 * otherwise, it must be a safe source.
844 if (uid_eq(cred
->fsuid
, inode
->i_uid
) || safe_hardlink_source(inode
) ||
848 audit_log_link_denied("linkat", link
);
852 static __always_inline
int
853 follow_link(struct path
*link
, struct nameidata
*nd
, void **p
)
855 struct dentry
*dentry
= link
->dentry
;
859 BUG_ON(nd
->flags
& LOOKUP_RCU
);
861 if (link
->mnt
== nd
->path
.mnt
)
865 if (unlikely(current
->total_link_count
>= 40))
866 goto out_put_nd_path
;
869 current
->total_link_count
++;
872 nd_set_link(nd
, NULL
);
874 error
= security_inode_follow_link(dentry
);
876 goto out_put_nd_path
;
878 nd
->last_type
= LAST_BIND
;
879 *p
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
882 goto out_put_nd_path
;
887 if (unlikely(IS_ERR(s
))) {
889 put_link(nd
, link
, *p
);
898 nd
->flags
|= LOOKUP_JUMPED
;
900 nd
->inode
= nd
->path
.dentry
->d_inode
;
901 error
= link_path_walk(s
, nd
);
903 put_link(nd
, link
, *p
);
915 static int follow_up_rcu(struct path
*path
)
917 struct mount
*mnt
= real_mount(path
->mnt
);
918 struct mount
*parent
;
919 struct dentry
*mountpoint
;
921 parent
= mnt
->mnt_parent
;
922 if (&parent
->mnt
== path
->mnt
)
924 mountpoint
= mnt
->mnt_mountpoint
;
925 path
->dentry
= mountpoint
;
926 path
->mnt
= &parent
->mnt
;
931 * follow_up - Find the mountpoint of path's vfsmount
933 * Given a path, find the mountpoint of its source file system.
934 * Replace @path with the path of the mountpoint in the parent mount.
937 * Return 1 if we went up a level and 0 if we were already at the
940 int follow_up(struct path
*path
)
942 struct mount
*mnt
= real_mount(path
->mnt
);
943 struct mount
*parent
;
944 struct dentry
*mountpoint
;
946 read_seqlock_excl(&mount_lock
);
947 parent
= mnt
->mnt_parent
;
949 read_sequnlock_excl(&mount_lock
);
952 mntget(&parent
->mnt
);
953 mountpoint
= dget(mnt
->mnt_mountpoint
);
954 read_sequnlock_excl(&mount_lock
);
956 path
->dentry
= mountpoint
;
958 path
->mnt
= &parent
->mnt
;
961 EXPORT_SYMBOL(follow_up
);
964 * Perform an automount
965 * - return -EISDIR to tell follow_managed() to stop and return the path we
968 static int follow_automount(struct path
*path
, unsigned flags
,
971 struct vfsmount
*mnt
;
974 if (!path
->dentry
->d_op
|| !path
->dentry
->d_op
->d_automount
)
977 /* We don't want to mount if someone's just doing a stat -
978 * unless they're stat'ing a directory and appended a '/' to
981 * We do, however, want to mount if someone wants to open or
982 * create a file of any type under the mountpoint, wants to
983 * traverse through the mountpoint or wants to open the
984 * mounted directory. Also, autofs may mark negative dentries
985 * as being automount points. These will need the attentions
986 * of the daemon to instantiate them before they can be used.
988 if (!(flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
989 LOOKUP_OPEN
| LOOKUP_CREATE
| LOOKUP_AUTOMOUNT
)) &&
990 path
->dentry
->d_inode
)
993 current
->total_link_count
++;
994 if (current
->total_link_count
>= 40)
997 mnt
= path
->dentry
->d_op
->d_automount(path
);
1000 * The filesystem is allowed to return -EISDIR here to indicate
1001 * it doesn't want to automount. For instance, autofs would do
1002 * this so that its userspace daemon can mount on this dentry.
1004 * However, we can only permit this if it's a terminal point in
1005 * the path being looked up; if it wasn't then the remainder of
1006 * the path is inaccessible and we should say so.
1008 if (PTR_ERR(mnt
) == -EISDIR
&& (flags
& LOOKUP_PARENT
))
1010 return PTR_ERR(mnt
);
1013 if (!mnt
) /* mount collision */
1016 if (!*need_mntput
) {
1017 /* lock_mount() may release path->mnt on error */
1019 *need_mntput
= true;
1021 err
= finish_automount(mnt
, path
);
1025 /* Someone else made a mount here whilst we were busy */
1030 path
->dentry
= dget(mnt
->mnt_root
);
1039 * Handle a dentry that is managed in some way.
1040 * - Flagged for transit management (autofs)
1041 * - Flagged as mountpoint
1042 * - Flagged as automount point
1044 * This may only be called in refwalk mode.
1046 * Serialization is taken care of in namespace.c
1048 static int follow_managed(struct path
*path
, unsigned flags
)
1050 struct vfsmount
*mnt
= path
->mnt
; /* held by caller, must be left alone */
1052 bool need_mntput
= false;
1055 /* Given that we're not holding a lock here, we retain the value in a
1056 * local variable for each dentry as we look at it so that we don't see
1057 * the components of that value change under us */
1058 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1059 managed
&= DCACHE_MANAGED_DENTRY
,
1060 unlikely(managed
!= 0)) {
1061 /* Allow the filesystem to manage the transit without i_mutex
1063 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1064 BUG_ON(!path
->dentry
->d_op
);
1065 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1066 ret
= path
->dentry
->d_op
->d_manage(path
->dentry
, false);
1071 /* Transit to a mounted filesystem. */
1072 if (managed
& DCACHE_MOUNTED
) {
1073 struct vfsmount
*mounted
= lookup_mnt(path
);
1078 path
->mnt
= mounted
;
1079 path
->dentry
= dget(mounted
->mnt_root
);
1084 /* Something is mounted on this dentry in another
1085 * namespace and/or whatever was mounted there in this
1086 * namespace got unmounted before lookup_mnt() could
1090 /* Handle an automount point */
1091 if (managed
& DCACHE_NEED_AUTOMOUNT
) {
1092 ret
= follow_automount(path
, flags
, &need_mntput
);
1098 /* We didn't change the current path point */
1102 if (need_mntput
&& path
->mnt
== mnt
)
1106 return ret
< 0 ? ret
: need_mntput
;
1109 int follow_down_one(struct path
*path
)
1111 struct vfsmount
*mounted
;
1113 mounted
= lookup_mnt(path
);
1117 path
->mnt
= mounted
;
1118 path
->dentry
= dget(mounted
->mnt_root
);
1123 EXPORT_SYMBOL(follow_down_one
);
1125 static inline int managed_dentry_rcu(struct dentry
*dentry
)
1127 return (dentry
->d_flags
& DCACHE_MANAGE_TRANSIT
) ?
1128 dentry
->d_op
->d_manage(dentry
, true) : 0;
1132 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1133 * we meet a managed dentry that would need blocking.
1135 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
,
1136 struct inode
**inode
)
1139 struct mount
*mounted
;
1141 * Don't forget we might have a non-mountpoint managed dentry
1142 * that wants to block transit.
1144 switch (managed_dentry_rcu(path
->dentry
)) {
1154 if (!d_mountpoint(path
->dentry
))
1155 return !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1157 mounted
= __lookup_mnt(path
->mnt
, path
->dentry
);
1160 path
->mnt
= &mounted
->mnt
;
1161 path
->dentry
= mounted
->mnt
.mnt_root
;
1162 nd
->flags
|= LOOKUP_JUMPED
;
1163 nd
->seq
= read_seqcount_begin(&path
->dentry
->d_seq
);
1165 * Update the inode too. We don't need to re-check the
1166 * dentry sequence number here after this d_inode read,
1167 * because a mount-point is always pinned.
1169 *inode
= path
->dentry
->d_inode
;
1171 return !read_seqretry(&mount_lock
, nd
->m_seq
) &&
1172 !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1175 static int follow_dotdot_rcu(struct nameidata
*nd
)
1177 struct inode
*inode
= nd
->inode
;
1182 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1183 nd
->path
.mnt
== nd
->root
.mnt
) {
1186 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1187 struct dentry
*old
= nd
->path
.dentry
;
1188 struct dentry
*parent
= old
->d_parent
;
1191 inode
= parent
->d_inode
;
1192 seq
= read_seqcount_begin(&parent
->d_seq
);
1193 if (read_seqcount_retry(&old
->d_seq
, nd
->seq
))
1195 nd
->path
.dentry
= parent
;
1199 if (!follow_up_rcu(&nd
->path
))
1201 inode
= nd
->path
.dentry
->d_inode
;
1202 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1204 while (d_mountpoint(nd
->path
.dentry
)) {
1205 struct mount
*mounted
;
1206 mounted
= __lookup_mnt(nd
->path
.mnt
, nd
->path
.dentry
);
1209 nd
->path
.mnt
= &mounted
->mnt
;
1210 nd
->path
.dentry
= mounted
->mnt
.mnt_root
;
1211 inode
= nd
->path
.dentry
->d_inode
;
1212 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1213 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1220 nd
->flags
&= ~LOOKUP_RCU
;
1221 if (!(nd
->flags
& LOOKUP_ROOT
))
1222 nd
->root
.mnt
= NULL
;
1228 * Follow down to the covering mount currently visible to userspace. At each
1229 * point, the filesystem owning that dentry may be queried as to whether the
1230 * caller is permitted to proceed or not.
1232 int follow_down(struct path
*path
)
1237 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1238 unlikely(managed
& DCACHE_MANAGED_DENTRY
)) {
1239 /* Allow the filesystem to manage the transit without i_mutex
1242 * We indicate to the filesystem if someone is trying to mount
1243 * something here. This gives autofs the chance to deny anyone
1244 * other than its daemon the right to mount on its
1247 * The filesystem may sleep at this point.
1249 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1250 BUG_ON(!path
->dentry
->d_op
);
1251 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1252 ret
= path
->dentry
->d_op
->d_manage(
1253 path
->dentry
, false);
1255 return ret
== -EISDIR
? 0 : ret
;
1258 /* Transit to a mounted filesystem. */
1259 if (managed
& DCACHE_MOUNTED
) {
1260 struct vfsmount
*mounted
= lookup_mnt(path
);
1265 path
->mnt
= mounted
;
1266 path
->dentry
= dget(mounted
->mnt_root
);
1270 /* Don't handle automount points here */
1275 EXPORT_SYMBOL(follow_down
);
1278 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1280 static void follow_mount(struct path
*path
)
1282 while (d_mountpoint(path
->dentry
)) {
1283 struct vfsmount
*mounted
= lookup_mnt(path
);
1288 path
->mnt
= mounted
;
1289 path
->dentry
= dget(mounted
->mnt_root
);
1293 static void follow_dotdot(struct nameidata
*nd
)
1299 struct dentry
*old
= nd
->path
.dentry
;
1301 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1302 nd
->path
.mnt
== nd
->root
.mnt
) {
1305 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1306 /* rare case of legitimate dget_parent()... */
1307 nd
->path
.dentry
= dget_parent(nd
->path
.dentry
);
1311 if (!follow_up(&nd
->path
))
1314 follow_mount(&nd
->path
);
1315 nd
->inode
= nd
->path
.dentry
->d_inode
;
1319 * This looks up the name in dcache, possibly revalidates the old dentry and
1320 * allocates a new one if not found or not valid. In the need_lookup argument
1321 * returns whether i_op->lookup is necessary.
1323 * dir->d_inode->i_mutex must be held
1325 static struct dentry
*lookup_dcache(struct qstr
*name
, struct dentry
*dir
,
1326 unsigned int flags
, bool *need_lookup
)
1328 struct dentry
*dentry
;
1331 *need_lookup
= false;
1332 dentry
= d_lookup(dir
, name
);
1334 if (dentry
->d_flags
& DCACHE_OP_REVALIDATE
) {
1335 error
= d_revalidate(dentry
, flags
);
1336 if (unlikely(error
<= 0)) {
1339 return ERR_PTR(error
);
1341 d_invalidate(dentry
);
1350 dentry
= d_alloc(dir
, name
);
1351 if (unlikely(!dentry
))
1352 return ERR_PTR(-ENOMEM
);
1354 *need_lookup
= true;
1360 * Call i_op->lookup on the dentry. The dentry must be negative and
1363 * dir->d_inode->i_mutex must be held
1365 static struct dentry
*lookup_real(struct inode
*dir
, struct dentry
*dentry
,
1370 /* Don't create child dentry for a dead directory. */
1371 if (unlikely(IS_DEADDIR(dir
))) {
1373 return ERR_PTR(-ENOENT
);
1376 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1377 if (unlikely(old
)) {
1384 static struct dentry
*__lookup_hash(struct qstr
*name
,
1385 struct dentry
*base
, unsigned int flags
)
1388 struct dentry
*dentry
;
1390 dentry
= lookup_dcache(name
, base
, flags
, &need_lookup
);
1394 return lookup_real(base
->d_inode
, dentry
, flags
);
1398 * It's more convoluted than I'd like it to be, but... it's still fairly
1399 * small and for now I'd prefer to have fast path as straight as possible.
1400 * It _is_ time-critical.
1402 static int lookup_fast(struct nameidata
*nd
,
1403 struct path
*path
, struct inode
**inode
)
1405 struct vfsmount
*mnt
= nd
->path
.mnt
;
1406 struct dentry
*dentry
, *parent
= nd
->path
.dentry
;
1412 * Rename seqlock is not required here because in the off chance
1413 * of a false negative due to a concurrent rename, we're going to
1414 * do the non-racy lookup, below.
1416 if (nd
->flags
& LOOKUP_RCU
) {
1419 dentry
= __d_lookup_rcu(parent
, &nd
->last
, &seq
);
1424 * This sequence count validates that the inode matches
1425 * the dentry name information from lookup.
1427 *inode
= dentry
->d_inode
;
1428 negative
= d_is_negative(dentry
);
1429 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
1435 * This sequence count validates that the parent had no
1436 * changes while we did the lookup of the dentry above.
1438 * The memory barrier in read_seqcount_begin of child is
1439 * enough, we can use __read_seqcount_retry here.
1441 if (__read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
1445 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
)) {
1446 status
= d_revalidate(dentry
, nd
->flags
);
1447 if (unlikely(status
<= 0)) {
1448 if (status
!= -ECHILD
)
1454 path
->dentry
= dentry
;
1455 if (likely(__follow_mount_rcu(nd
, path
, inode
)))
1458 if (unlazy_walk(nd
, dentry
))
1461 dentry
= __d_lookup(parent
, &nd
->last
);
1464 if (unlikely(!dentry
))
1467 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
) && need_reval
)
1468 status
= d_revalidate(dentry
, nd
->flags
);
1469 if (unlikely(status
<= 0)) {
1474 d_invalidate(dentry
);
1479 if (unlikely(d_is_negative(dentry
))) {
1484 path
->dentry
= dentry
;
1485 err
= follow_managed(path
, nd
->flags
);
1486 if (unlikely(err
< 0)) {
1487 path_put_conditional(path
, nd
);
1491 nd
->flags
|= LOOKUP_JUMPED
;
1492 *inode
= path
->dentry
->d_inode
;
1499 /* Fast lookup failed, do it the slow way */
1500 static int lookup_slow(struct nameidata
*nd
, struct path
*path
)
1502 struct dentry
*dentry
, *parent
;
1505 parent
= nd
->path
.dentry
;
1506 BUG_ON(nd
->inode
!= parent
->d_inode
);
1508 mutex_lock(&parent
->d_inode
->i_mutex
);
1509 dentry
= __lookup_hash(&nd
->last
, parent
, nd
->flags
);
1510 mutex_unlock(&parent
->d_inode
->i_mutex
);
1512 return PTR_ERR(dentry
);
1513 path
->mnt
= nd
->path
.mnt
;
1514 path
->dentry
= dentry
;
1515 err
= follow_managed(path
, nd
->flags
);
1516 if (unlikely(err
< 0)) {
1517 path_put_conditional(path
, nd
);
1521 nd
->flags
|= LOOKUP_JUMPED
;
1525 static inline int may_lookup(struct nameidata
*nd
)
1527 if (nd
->flags
& LOOKUP_RCU
) {
1528 int err
= inode_permission(nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1531 if (unlazy_walk(nd
, NULL
))
1534 return inode_permission(nd
->inode
, MAY_EXEC
);
1537 static inline int handle_dots(struct nameidata
*nd
, int type
)
1539 if (type
== LAST_DOTDOT
) {
1540 if (nd
->flags
& LOOKUP_RCU
) {
1541 if (follow_dotdot_rcu(nd
))
1549 static void terminate_walk(struct nameidata
*nd
)
1551 if (!(nd
->flags
& LOOKUP_RCU
)) {
1552 path_put(&nd
->path
);
1554 nd
->flags
&= ~LOOKUP_RCU
;
1555 if (!(nd
->flags
& LOOKUP_ROOT
))
1556 nd
->root
.mnt
= NULL
;
1562 * Do we need to follow links? We _really_ want to be able
1563 * to do this check without having to look at inode->i_op,
1564 * so we keep a cache of "no, this doesn't need follow_link"
1565 * for the common case.
1567 static inline int should_follow_link(struct dentry
*dentry
, int follow
)
1569 return unlikely(d_is_symlink(dentry
)) ? follow
: 0;
1572 static int walk_component(struct nameidata
*nd
, struct path
*path
, int follow
)
1574 struct inode
*inode
;
1577 * "." and ".." are special - ".." especially so because it has
1578 * to be able to know about the current root directory and
1579 * parent relationships.
1581 if (unlikely(nd
->last_type
!= LAST_NORM
))
1582 return handle_dots(nd
, nd
->last_type
);
1583 err
= lookup_fast(nd
, path
, &inode
);
1584 if (unlikely(err
)) {
1588 err
= lookup_slow(nd
, path
);
1592 inode
= path
->dentry
->d_inode
;
1594 if (d_is_negative(path
->dentry
))
1598 if (should_follow_link(path
->dentry
, follow
)) {
1599 if (nd
->flags
& LOOKUP_RCU
) {
1600 if (unlikely(nd
->path
.mnt
!= path
->mnt
||
1601 unlazy_walk(nd
, path
->dentry
))) {
1606 BUG_ON(inode
!= path
->dentry
->d_inode
);
1609 path_to_nameidata(path
, nd
);
1614 path_to_nameidata(path
, nd
);
1621 * This limits recursive symlink follows to 8, while
1622 * limiting consecutive symlinks to 40.
1624 * Without that kind of total limit, nasty chains of consecutive
1625 * symlinks can cause almost arbitrarily long lookups.
1627 static inline int nested_symlink(struct path
*path
, struct nameidata
*nd
)
1631 if (unlikely(current
->link_count
>= MAX_NESTED_LINKS
)) {
1632 path_put_conditional(path
, nd
);
1633 path_put(&nd
->path
);
1636 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
1639 current
->link_count
++;
1642 struct path link
= *path
;
1645 res
= follow_link(&link
, nd
, &cookie
);
1648 res
= walk_component(nd
, path
, LOOKUP_FOLLOW
);
1649 put_link(nd
, &link
, cookie
);
1652 current
->link_count
--;
1658 * We can do the critical dentry name comparison and hashing
1659 * operations one word at a time, but we are limited to:
1661 * - Architectures with fast unaligned word accesses. We could
1662 * do a "get_unaligned()" if this helps and is sufficiently
1665 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1666 * do not trap on the (extremely unlikely) case of a page
1667 * crossing operation.
1669 * - Furthermore, we need an efficient 64-bit compile for the
1670 * 64-bit case in order to generate the "number of bytes in
1671 * the final mask". Again, that could be replaced with a
1672 * efficient population count instruction or similar.
1674 #ifdef CONFIG_DCACHE_WORD_ACCESS
1676 #include <asm/word-at-a-time.h>
1680 static inline unsigned int fold_hash(unsigned long hash
)
1682 return hash_64(hash
, 32);
1685 #else /* 32-bit case */
1687 #define fold_hash(x) (x)
1691 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1693 unsigned long a
, mask
;
1694 unsigned long hash
= 0;
1697 a
= load_unaligned_zeropad(name
);
1698 if (len
< sizeof(unsigned long))
1702 name
+= sizeof(unsigned long);
1703 len
-= sizeof(unsigned long);
1707 mask
= bytemask_from_count(len
);
1710 return fold_hash(hash
);
1712 EXPORT_SYMBOL(full_name_hash
);
1715 * Calculate the length and hash of the path component, and
1716 * return the "hash_len" as the result.
1718 static inline u64
hash_name(const char *name
)
1720 unsigned long a
, b
, adata
, bdata
, mask
, hash
, len
;
1721 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
1724 len
= -sizeof(unsigned long);
1726 hash
= (hash
+ a
) * 9;
1727 len
+= sizeof(unsigned long);
1728 a
= load_unaligned_zeropad(name
+len
);
1729 b
= a
^ REPEAT_BYTE('/');
1730 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
1732 adata
= prep_zero_mask(a
, adata
, &constants
);
1733 bdata
= prep_zero_mask(b
, bdata
, &constants
);
1735 mask
= create_zero_mask(adata
| bdata
);
1737 hash
+= a
& zero_bytemask(mask
);
1738 len
+= find_zero(mask
);
1739 return hashlen_create(fold_hash(hash
), len
);
1744 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1746 unsigned long hash
= init_name_hash();
1748 hash
= partial_name_hash(*name
++, hash
);
1749 return end_name_hash(hash
);
1751 EXPORT_SYMBOL(full_name_hash
);
1754 * We know there's a real path component here of at least
1757 static inline u64
hash_name(const char *name
)
1759 unsigned long hash
= init_name_hash();
1760 unsigned long len
= 0, c
;
1762 c
= (unsigned char)*name
;
1765 hash
= partial_name_hash(c
, hash
);
1766 c
= (unsigned char)name
[len
];
1767 } while (c
&& c
!= '/');
1768 return hashlen_create(end_name_hash(hash
), len
);
1775 * This is the basic name resolution function, turning a pathname into
1776 * the final dentry. We expect 'base' to be positive and a directory.
1778 * Returns 0 and nd will have valid dentry and mnt on success.
1779 * Returns error and drops reference to input namei data on failure.
1781 static int link_path_walk(const char *name
, struct nameidata
*nd
)
1791 /* At this point we know we have a real path component. */
1796 err
= may_lookup(nd
);
1800 hash_len
= hash_name(name
);
1803 if (name
[0] == '.') switch (hashlen_len(hash_len
)) {
1805 if (name
[1] == '.') {
1807 nd
->flags
|= LOOKUP_JUMPED
;
1813 if (likely(type
== LAST_NORM
)) {
1814 struct dentry
*parent
= nd
->path
.dentry
;
1815 nd
->flags
&= ~LOOKUP_JUMPED
;
1816 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
1817 struct qstr
this = { { .hash_len
= hash_len
}, .name
= name
};
1818 err
= parent
->d_op
->d_hash(parent
, &this);
1821 hash_len
= this.hash_len
;
1826 nd
->last
.hash_len
= hash_len
;
1827 nd
->last
.name
= name
;
1828 nd
->last_type
= type
;
1830 name
+= hashlen_len(hash_len
);
1834 * If it wasn't NUL, we know it was '/'. Skip that
1835 * slash, and continue until no more slashes.
1839 } while (unlikely(*name
== '/'));
1843 err
= walk_component(nd
, &next
, LOOKUP_FOLLOW
);
1848 err
= nested_symlink(&next
, nd
);
1852 if (!d_can_lookup(nd
->path
.dentry
)) {
1861 static int path_init(int dfd
, const struct filename
*name
, unsigned int flags
,
1862 struct nameidata
*nd
)
1865 const char *s
= name
->name
;
1867 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1868 nd
->flags
= flags
| LOOKUP_JUMPED
| LOOKUP_PARENT
;
1871 if (flags
& LOOKUP_ROOT
) {
1872 struct dentry
*root
= nd
->root
.dentry
;
1873 struct inode
*inode
= root
->d_inode
;
1875 if (!d_can_lookup(root
))
1877 retval
= inode_permission(inode
, MAY_EXEC
);
1881 nd
->path
= nd
->root
;
1883 if (flags
& LOOKUP_RCU
) {
1885 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1886 nd
->m_seq
= read_seqbegin(&mount_lock
);
1888 path_get(&nd
->path
);
1893 nd
->root
.mnt
= NULL
;
1895 nd
->m_seq
= read_seqbegin(&mount_lock
);
1897 if (flags
& LOOKUP_RCU
) {
1899 nd
->seq
= set_root_rcu(nd
);
1902 path_get(&nd
->root
);
1904 nd
->path
= nd
->root
;
1905 } else if (dfd
== AT_FDCWD
) {
1906 if (flags
& LOOKUP_RCU
) {
1907 struct fs_struct
*fs
= current
->fs
;
1913 seq
= read_seqcount_begin(&fs
->seq
);
1915 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1916 } while (read_seqcount_retry(&fs
->seq
, seq
));
1918 get_fs_pwd(current
->fs
, &nd
->path
);
1921 /* Caller must check execute permissions on the starting path component */
1922 struct fd f
= fdget_raw(dfd
);
1923 struct dentry
*dentry
;
1928 dentry
= f
.file
->f_path
.dentry
;
1931 if (!d_can_lookup(dentry
)) {
1937 nd
->path
= f
.file
->f_path
;
1938 if (flags
& LOOKUP_RCU
) {
1939 if (f
.flags
& FDPUT_FPUT
)
1941 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1944 path_get(&nd
->path
);
1949 nd
->inode
= nd
->path
.dentry
->d_inode
;
1950 if (!(flags
& LOOKUP_RCU
))
1952 if (likely(!read_seqcount_retry(&nd
->path
.dentry
->d_seq
, nd
->seq
)))
1954 if (!(nd
->flags
& LOOKUP_ROOT
))
1955 nd
->root
.mnt
= NULL
;
1959 current
->total_link_count
= 0;
1960 return link_path_walk(s
, nd
);
1963 static void path_cleanup(struct nameidata
*nd
)
1965 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
1966 path_put(&nd
->root
);
1967 nd
->root
.mnt
= NULL
;
1969 if (unlikely(nd
->base
))
1973 static inline int lookup_last(struct nameidata
*nd
, struct path
*path
)
1975 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
1976 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
1978 nd
->flags
&= ~LOOKUP_PARENT
;
1979 return walk_component(nd
, path
, nd
->flags
& LOOKUP_FOLLOW
);
1982 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1983 static int path_lookupat(int dfd
, const struct filename
*name
,
1984 unsigned int flags
, struct nameidata
*nd
)
1990 * Path walking is largely split up into 2 different synchronisation
1991 * schemes, rcu-walk and ref-walk (explained in
1992 * Documentation/filesystems/path-lookup.txt). These share much of the
1993 * path walk code, but some things particularly setup, cleanup, and
1994 * following mounts are sufficiently divergent that functions are
1995 * duplicated. Typically there is a function foo(), and its RCU
1996 * analogue, foo_rcu().
1998 * -ECHILD is the error number of choice (just to avoid clashes) that
1999 * is returned if some aspect of an rcu-walk fails. Such an error must
2000 * be handled by restarting a traditional ref-walk (which will always
2001 * be able to complete).
2003 err
= path_init(dfd
, name
, flags
, nd
);
2004 if (!err
&& !(flags
& LOOKUP_PARENT
)) {
2005 err
= lookup_last(nd
, &path
);
2008 struct path link
= path
;
2009 err
= may_follow_link(&link
, nd
);
2012 nd
->flags
|= LOOKUP_PARENT
;
2013 err
= follow_link(&link
, nd
, &cookie
);
2016 err
= lookup_last(nd
, &path
);
2017 put_link(nd
, &link
, cookie
);
2022 err
= complete_walk(nd
);
2024 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
) {
2025 if (!d_can_lookup(nd
->path
.dentry
)) {
2026 path_put(&nd
->path
);
2035 static int filename_lookup(int dfd
, struct filename
*name
,
2036 unsigned int flags
, struct nameidata
*nd
)
2038 int retval
= path_lookupat(dfd
, name
, flags
| LOOKUP_RCU
, nd
);
2039 if (unlikely(retval
== -ECHILD
))
2040 retval
= path_lookupat(dfd
, name
, flags
, nd
);
2041 if (unlikely(retval
== -ESTALE
))
2042 retval
= path_lookupat(dfd
, name
, flags
| LOOKUP_REVAL
, nd
);
2044 if (likely(!retval
))
2045 audit_inode(name
, nd
->path
.dentry
, flags
& LOOKUP_PARENT
);
2049 /* does lookup, returns the object with parent locked */
2050 struct dentry
*kern_path_locked(const char *name
, struct path
*path
)
2052 struct filename
*filename
= getname_kernel(name
);
2053 struct nameidata nd
;
2057 if (IS_ERR(filename
))
2058 return ERR_CAST(filename
);
2060 err
= filename_lookup(AT_FDCWD
, filename
, LOOKUP_PARENT
, &nd
);
2065 if (nd
.last_type
!= LAST_NORM
) {
2067 d
= ERR_PTR(-EINVAL
);
2070 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2071 d
= __lookup_hash(&nd
.last
, nd
.path
.dentry
, 0);
2073 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2083 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
2085 struct nameidata nd
;
2086 struct filename
*filename
= getname_kernel(name
);
2087 int res
= PTR_ERR(filename
);
2089 if (!IS_ERR(filename
)) {
2090 res
= filename_lookup(AT_FDCWD
, filename
, flags
, &nd
);
2097 EXPORT_SYMBOL(kern_path
);
2100 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2101 * @dentry: pointer to dentry of the base directory
2102 * @mnt: pointer to vfs mount of the base directory
2103 * @name: pointer to file name
2104 * @flags: lookup flags
2105 * @path: pointer to struct path to fill
2107 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
2108 const char *name
, unsigned int flags
,
2111 struct filename
*filename
= getname_kernel(name
);
2112 int err
= PTR_ERR(filename
);
2114 BUG_ON(flags
& LOOKUP_PARENT
);
2116 /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */
2117 if (!IS_ERR(filename
)) {
2118 struct nameidata nd
;
2119 nd
.root
.dentry
= dentry
;
2121 err
= filename_lookup(AT_FDCWD
, filename
,
2122 flags
| LOOKUP_ROOT
, &nd
);
2129 EXPORT_SYMBOL(vfs_path_lookup
);
2132 * Restricted form of lookup. Doesn't follow links, single-component only,
2133 * needs parent already locked. Doesn't follow mounts.
2136 static struct dentry
*lookup_hash(struct nameidata
*nd
)
2138 return __lookup_hash(&nd
->last
, nd
->path
.dentry
, nd
->flags
);
2142 * lookup_one_len - filesystem helper to lookup single pathname component
2143 * @name: pathname component to lookup
2144 * @base: base directory to lookup from
2145 * @len: maximum length @len should be interpreted to
2147 * Note that this routine is purely a helper for filesystem usage and should
2148 * not be called by generic code.
2150 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2156 WARN_ON_ONCE(!mutex_is_locked(&base
->d_inode
->i_mutex
));
2160 this.hash
= full_name_hash(name
, len
);
2162 return ERR_PTR(-EACCES
);
2164 if (unlikely(name
[0] == '.')) {
2165 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2166 return ERR_PTR(-EACCES
);
2170 c
= *(const unsigned char *)name
++;
2171 if (c
== '/' || c
== '\0')
2172 return ERR_PTR(-EACCES
);
2175 * See if the low-level filesystem might want
2176 * to use its own hash..
2178 if (base
->d_flags
& DCACHE_OP_HASH
) {
2179 int err
= base
->d_op
->d_hash(base
, &this);
2181 return ERR_PTR(err
);
2184 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
2186 return ERR_PTR(err
);
2188 return __lookup_hash(&this, base
, 0);
2190 EXPORT_SYMBOL(lookup_one_len
);
2192 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
2193 struct path
*path
, int *empty
)
2195 struct nameidata nd
;
2196 struct filename
*tmp
= getname_flags(name
, flags
, empty
);
2197 int err
= PTR_ERR(tmp
);
2200 BUG_ON(flags
& LOOKUP_PARENT
);
2202 err
= filename_lookup(dfd
, tmp
, flags
, &nd
);
2210 int user_path_at(int dfd
, const char __user
*name
, unsigned flags
,
2213 return user_path_at_empty(dfd
, name
, flags
, path
, NULL
);
2215 EXPORT_SYMBOL(user_path_at
);
2218 * NB: most callers don't do anything directly with the reference to the
2219 * to struct filename, but the nd->last pointer points into the name string
2220 * allocated by getname. So we must hold the reference to it until all
2221 * path-walking is complete.
2223 static struct filename
*
2224 user_path_parent(int dfd
, const char __user
*path
, struct nameidata
*nd
,
2227 struct filename
*s
= getname(path
);
2230 /* only LOOKUP_REVAL is allowed in extra flags */
2231 flags
&= LOOKUP_REVAL
;
2236 error
= filename_lookup(dfd
, s
, flags
| LOOKUP_PARENT
, nd
);
2239 return ERR_PTR(error
);
2246 * mountpoint_last - look up last component for umount
2247 * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
2248 * @path: pointer to container for result
2250 * This is a special lookup_last function just for umount. In this case, we
2251 * need to resolve the path without doing any revalidation.
2253 * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
2254 * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
2255 * in almost all cases, this lookup will be served out of the dcache. The only
2256 * cases where it won't are if nd->last refers to a symlink or the path is
2257 * bogus and it doesn't exist.
2260 * -error: if there was an error during lookup. This includes -ENOENT if the
2261 * lookup found a negative dentry. The nd->path reference will also be
2264 * 0: if we successfully resolved nd->path and found it to not to be a
2265 * symlink that needs to be followed. "path" will also be populated.
2266 * The nd->path reference will also be put.
2268 * 1: if we successfully resolved nd->last and found it to be a symlink
2269 * that needs to be followed. "path" will be populated with the path
2270 * to the link, and nd->path will *not* be put.
2273 mountpoint_last(struct nameidata
*nd
, struct path
*path
)
2276 struct dentry
*dentry
;
2277 struct dentry
*dir
= nd
->path
.dentry
;
2279 /* If we're in rcuwalk, drop out of it to handle last component */
2280 if (nd
->flags
& LOOKUP_RCU
) {
2281 if (unlazy_walk(nd
, NULL
)) {
2287 nd
->flags
&= ~LOOKUP_PARENT
;
2289 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
2290 error
= handle_dots(nd
, nd
->last_type
);
2293 dentry
= dget(nd
->path
.dentry
);
2297 mutex_lock(&dir
->d_inode
->i_mutex
);
2298 dentry
= d_lookup(dir
, &nd
->last
);
2301 * No cached dentry. Mounted dentries are pinned in the cache,
2302 * so that means that this dentry is probably a symlink or the
2303 * path doesn't actually point to a mounted dentry.
2305 dentry
= d_alloc(dir
, &nd
->last
);
2308 mutex_unlock(&dir
->d_inode
->i_mutex
);
2311 dentry
= lookup_real(dir
->d_inode
, dentry
, nd
->flags
);
2312 error
= PTR_ERR(dentry
);
2313 if (IS_ERR(dentry
)) {
2314 mutex_unlock(&dir
->d_inode
->i_mutex
);
2318 mutex_unlock(&dir
->d_inode
->i_mutex
);
2321 if (d_is_negative(dentry
)) {
2326 path
->dentry
= dentry
;
2327 path
->mnt
= nd
->path
.mnt
;
2328 if (should_follow_link(dentry
, nd
->flags
& LOOKUP_FOLLOW
))
2339 * path_mountpoint - look up a path to be umounted
2340 * @dfd: directory file descriptor to start walk from
2341 * @name: full pathname to walk
2342 * @path: pointer to container for result
2343 * @flags: lookup flags
2345 * Look up the given name, but don't attempt to revalidate the last component.
2346 * Returns 0 and "path" will be valid on success; Returns error otherwise.
2349 path_mountpoint(int dfd
, const struct filename
*name
, struct path
*path
,
2352 struct nameidata nd
;
2355 err
= path_init(dfd
, name
, flags
, &nd
);
2359 err
= mountpoint_last(&nd
, path
);
2362 struct path link
= *path
;
2363 err
= may_follow_link(&link
, &nd
);
2366 nd
.flags
|= LOOKUP_PARENT
;
2367 err
= follow_link(&link
, &nd
, &cookie
);
2370 err
= mountpoint_last(&nd
, path
);
2371 put_link(&nd
, &link
, cookie
);
2379 filename_mountpoint(int dfd
, struct filename
*name
, struct path
*path
,
2384 return PTR_ERR(name
);
2385 error
= path_mountpoint(dfd
, name
, path
, flags
| LOOKUP_RCU
);
2386 if (unlikely(error
== -ECHILD
))
2387 error
= path_mountpoint(dfd
, name
, path
, flags
);
2388 if (unlikely(error
== -ESTALE
))
2389 error
= path_mountpoint(dfd
, name
, path
, flags
| LOOKUP_REVAL
);
2391 audit_inode(name
, path
->dentry
, 0);
2397 * user_path_mountpoint_at - lookup a path from userland in order to umount it
2398 * @dfd: directory file descriptor
2399 * @name: pathname from userland
2400 * @flags: lookup flags
2401 * @path: pointer to container to hold result
2403 * A umount is a special case for path walking. We're not actually interested
2404 * in the inode in this situation, and ESTALE errors can be a problem. We
2405 * simply want track down the dentry and vfsmount attached at the mountpoint
2406 * and avoid revalidating the last component.
2408 * Returns 0 and populates "path" on success.
2411 user_path_mountpoint_at(int dfd
, const char __user
*name
, unsigned int flags
,
2414 return filename_mountpoint(dfd
, getname(name
), path
, flags
);
2418 kern_path_mountpoint(int dfd
, const char *name
, struct path
*path
,
2421 return filename_mountpoint(dfd
, getname_kernel(name
), path
, flags
);
2423 EXPORT_SYMBOL(kern_path_mountpoint
);
2425 int __check_sticky(struct inode
*dir
, struct inode
*inode
)
2427 kuid_t fsuid
= current_fsuid();
2429 if (uid_eq(inode
->i_uid
, fsuid
))
2431 if (uid_eq(dir
->i_uid
, fsuid
))
2433 return !capable_wrt_inode_uidgid(inode
, CAP_FOWNER
);
2435 EXPORT_SYMBOL(__check_sticky
);
2438 * Check whether we can remove a link victim from directory dir, check
2439 * whether the type of victim is right.
2440 * 1. We can't do it if dir is read-only (done in permission())
2441 * 2. We should have write and exec permissions on dir
2442 * 3. We can't remove anything from append-only dir
2443 * 4. We can't do anything with immutable dir (done in permission())
2444 * 5. If the sticky bit on dir is set we should either
2445 * a. be owner of dir, or
2446 * b. be owner of victim, or
2447 * c. have CAP_FOWNER capability
2448 * 6. If the victim is append-only or immutable we can't do antyhing with
2449 * links pointing to it.
2450 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2451 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2452 * 9. We can't remove a root or mountpoint.
2453 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
2454 * nfs_async_unlink().
2456 static int may_delete(struct inode
*dir
, struct dentry
*victim
, bool isdir
)
2458 struct inode
*inode
= victim
->d_inode
;
2461 if (d_is_negative(victim
))
2465 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
2466 audit_inode_child(dir
, victim
, AUDIT_TYPE_CHILD_DELETE
);
2468 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2474 if (check_sticky(dir
, inode
) || IS_APPEND(inode
) ||
2475 IS_IMMUTABLE(inode
) || IS_SWAPFILE(inode
))
2478 if (!d_is_dir(victim
))
2480 if (IS_ROOT(victim
))
2482 } else if (d_is_dir(victim
))
2484 if (IS_DEADDIR(dir
))
2486 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2491 /* Check whether we can create an object with dentry child in directory
2493 * 1. We can't do it if child already exists (open has special treatment for
2494 * this case, but since we are inlined it's OK)
2495 * 2. We can't do it if dir is read-only (done in permission())
2496 * 3. We should have write and exec permissions on dir
2497 * 4. We can't do it if dir is immutable (done in permission())
2499 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
2501 audit_inode_child(dir
, child
, AUDIT_TYPE_CHILD_CREATE
);
2504 if (IS_DEADDIR(dir
))
2506 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2510 * p1 and p2 should be directories on the same fs.
2512 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2517 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2521 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2523 p
= d_ancestor(p2
, p1
);
2525 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2526 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2530 p
= d_ancestor(p1
, p2
);
2532 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2533 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2537 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2538 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT2
);
2541 EXPORT_SYMBOL(lock_rename
);
2543 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
2545 mutex_unlock(&p1
->d_inode
->i_mutex
);
2547 mutex_unlock(&p2
->d_inode
->i_mutex
);
2548 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2551 EXPORT_SYMBOL(unlock_rename
);
2553 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
2556 int error
= may_create(dir
, dentry
);
2560 if (!dir
->i_op
->create
)
2561 return -EACCES
; /* shouldn't it be ENOSYS? */
2564 error
= security_inode_create(dir
, dentry
, mode
);
2567 error
= dir
->i_op
->create(dir
, dentry
, mode
, want_excl
);
2569 fsnotify_create(dir
, dentry
);
2572 EXPORT_SYMBOL(vfs_create
);
2574 static int may_open(struct path
*path
, int acc_mode
, int flag
)
2576 struct dentry
*dentry
= path
->dentry
;
2577 struct inode
*inode
= dentry
->d_inode
;
2587 switch (inode
->i_mode
& S_IFMT
) {
2591 if (acc_mode
& MAY_WRITE
)
2596 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
2605 error
= inode_permission(inode
, acc_mode
);
2610 * An append-only file must be opened in append mode for writing.
2612 if (IS_APPEND(inode
)) {
2613 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
2619 /* O_NOATIME can only be set by the owner or superuser */
2620 if (flag
& O_NOATIME
&& !inode_owner_or_capable(inode
))
2626 static int handle_truncate(struct file
*filp
)
2628 struct path
*path
= &filp
->f_path
;
2629 struct inode
*inode
= path
->dentry
->d_inode
;
2630 int error
= get_write_access(inode
);
2634 * Refuse to truncate files with mandatory locks held on them.
2636 error
= locks_verify_locked(filp
);
2638 error
= security_path_truncate(path
);
2640 error
= do_truncate(path
->dentry
, 0,
2641 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
2644 put_write_access(inode
);
2648 static inline int open_to_namei_flags(int flag
)
2650 if ((flag
& O_ACCMODE
) == 3)
2655 static int may_o_create(struct path
*dir
, struct dentry
*dentry
, umode_t mode
)
2657 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
2661 error
= inode_permission(dir
->dentry
->d_inode
, MAY_WRITE
| MAY_EXEC
);
2665 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
2669 * Attempt to atomically look up, create and open a file from a negative
2672 * Returns 0 if successful. The file will have been created and attached to
2673 * @file by the filesystem calling finish_open().
2675 * Returns 1 if the file was looked up only or didn't need creating. The
2676 * caller will need to perform the open themselves. @path will have been
2677 * updated to point to the new dentry. This may be negative.
2679 * Returns an error code otherwise.
2681 static int atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
2682 struct path
*path
, struct file
*file
,
2683 const struct open_flags
*op
,
2684 bool got_write
, bool need_lookup
,
2687 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
2688 unsigned open_flag
= open_to_namei_flags(op
->open_flag
);
2692 int create_error
= 0;
2693 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
2696 BUG_ON(dentry
->d_inode
);
2698 /* Don't create child dentry for a dead directory. */
2699 if (unlikely(IS_DEADDIR(dir
))) {
2705 if ((open_flag
& O_CREAT
) && !IS_POSIXACL(dir
))
2706 mode
&= ~current_umask();
2708 excl
= (open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
);
2710 open_flag
&= ~O_TRUNC
;
2713 * Checking write permission is tricky, bacuse we don't know if we are
2714 * going to actually need it: O_CREAT opens should work as long as the
2715 * file exists. But checking existence breaks atomicity. The trick is
2716 * to check access and if not granted clear O_CREAT from the flags.
2718 * Another problem is returing the "right" error value (e.g. for an
2719 * O_EXCL open we want to return EEXIST not EROFS).
2721 if (((open_flag
& (O_CREAT
| O_TRUNC
)) ||
2722 (open_flag
& O_ACCMODE
) != O_RDONLY
) && unlikely(!got_write
)) {
2723 if (!(open_flag
& O_CREAT
)) {
2725 * No O_CREATE -> atomicity not a requirement -> fall
2726 * back to lookup + open
2729 } else if (open_flag
& (O_EXCL
| O_TRUNC
)) {
2730 /* Fall back and fail with the right error */
2731 create_error
= -EROFS
;
2734 /* No side effects, safe to clear O_CREAT */
2735 create_error
= -EROFS
;
2736 open_flag
&= ~O_CREAT
;
2740 if (open_flag
& O_CREAT
) {
2741 error
= may_o_create(&nd
->path
, dentry
, mode
);
2743 create_error
= error
;
2744 if (open_flag
& O_EXCL
)
2746 open_flag
&= ~O_CREAT
;
2750 if (nd
->flags
& LOOKUP_DIRECTORY
)
2751 open_flag
|= O_DIRECTORY
;
2753 file
->f_path
.dentry
= DENTRY_NOT_SET
;
2754 file
->f_path
.mnt
= nd
->path
.mnt
;
2755 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
, open_flag
, mode
,
2758 if (create_error
&& error
== -ENOENT
)
2759 error
= create_error
;
2763 if (error
) { /* returned 1, that is */
2764 if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
2768 if (file
->f_path
.dentry
) {
2770 dentry
= file
->f_path
.dentry
;
2772 if (*opened
& FILE_CREATED
)
2773 fsnotify_create(dir
, dentry
);
2774 if (!dentry
->d_inode
) {
2775 WARN_ON(*opened
& FILE_CREATED
);
2777 error
= create_error
;
2781 if (excl
&& !(*opened
& FILE_CREATED
)) {
2790 * We didn't have the inode before the open, so check open permission
2793 acc_mode
= op
->acc_mode
;
2794 if (*opened
& FILE_CREATED
) {
2795 WARN_ON(!(open_flag
& O_CREAT
));
2796 fsnotify_create(dir
, dentry
);
2797 acc_mode
= MAY_OPEN
;
2799 error
= may_open(&file
->f_path
, acc_mode
, open_flag
);
2809 dentry
= lookup_real(dir
, dentry
, nd
->flags
);
2811 return PTR_ERR(dentry
);
2814 int open_flag
= op
->open_flag
;
2816 error
= create_error
;
2817 if ((open_flag
& O_EXCL
)) {
2818 if (!dentry
->d_inode
)
2820 } else if (!dentry
->d_inode
) {
2822 } else if ((open_flag
& O_TRUNC
) &&
2826 /* will fail later, go on to get the right error */
2830 path
->dentry
= dentry
;
2831 path
->mnt
= nd
->path
.mnt
;
2836 * Look up and maybe create and open the last component.
2838 * Must be called with i_mutex held on parent.
2840 * Returns 0 if the file was successfully atomically created (if necessary) and
2841 * opened. In this case the file will be returned attached to @file.
2843 * Returns 1 if the file was not completely opened at this time, though lookups
2844 * and creations will have been performed and the dentry returned in @path will
2845 * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
2846 * specified then a negative dentry may be returned.
2848 * An error code is returned otherwise.
2850 * FILE_CREATE will be set in @*opened if the dentry was created and will be
2851 * cleared otherwise prior to returning.
2853 static int lookup_open(struct nameidata
*nd
, struct path
*path
,
2855 const struct open_flags
*op
,
2856 bool got_write
, int *opened
)
2858 struct dentry
*dir
= nd
->path
.dentry
;
2859 struct inode
*dir_inode
= dir
->d_inode
;
2860 struct dentry
*dentry
;
2864 *opened
&= ~FILE_CREATED
;
2865 dentry
= lookup_dcache(&nd
->last
, dir
, nd
->flags
, &need_lookup
);
2867 return PTR_ERR(dentry
);
2869 /* Cached positive dentry: will open in f_op->open */
2870 if (!need_lookup
&& dentry
->d_inode
)
2873 if ((nd
->flags
& LOOKUP_OPEN
) && dir_inode
->i_op
->atomic_open
) {
2874 return atomic_open(nd
, dentry
, path
, file
, op
, got_write
,
2875 need_lookup
, opened
);
2879 BUG_ON(dentry
->d_inode
);
2881 dentry
= lookup_real(dir_inode
, dentry
, nd
->flags
);
2883 return PTR_ERR(dentry
);
2886 /* Negative dentry, just create the file */
2887 if (!dentry
->d_inode
&& (op
->open_flag
& O_CREAT
)) {
2888 umode_t mode
= op
->mode
;
2889 if (!IS_POSIXACL(dir
->d_inode
))
2890 mode
&= ~current_umask();
2892 * This write is needed to ensure that a
2893 * rw->ro transition does not occur between
2894 * the time when the file is created and when
2895 * a permanent write count is taken through
2896 * the 'struct file' in finish_open().
2902 *opened
|= FILE_CREATED
;
2903 error
= security_path_mknod(&nd
->path
, dentry
, mode
, 0);
2906 error
= vfs_create(dir
->d_inode
, dentry
, mode
,
2907 nd
->flags
& LOOKUP_EXCL
);
2912 path
->dentry
= dentry
;
2913 path
->mnt
= nd
->path
.mnt
;
2922 * Handle the last step of open()
2924 static int do_last(struct nameidata
*nd
, struct path
*path
,
2925 struct file
*file
, const struct open_flags
*op
,
2926 int *opened
, struct filename
*name
)
2928 struct dentry
*dir
= nd
->path
.dentry
;
2929 int open_flag
= op
->open_flag
;
2930 bool will_truncate
= (open_flag
& O_TRUNC
) != 0;
2931 bool got_write
= false;
2932 int acc_mode
= op
->acc_mode
;
2933 struct inode
*inode
;
2934 struct path save_parent
= { .dentry
= NULL
, .mnt
= NULL
};
2935 bool retried
= false;
2938 nd
->flags
&= ~LOOKUP_PARENT
;
2939 nd
->flags
|= op
->intent
;
2941 if (nd
->last_type
!= LAST_NORM
) {
2942 error
= handle_dots(nd
, nd
->last_type
);
2948 if (!(open_flag
& O_CREAT
)) {
2949 if (nd
->last
.name
[nd
->last
.len
])
2950 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2951 /* we _can_ be in RCU mode here */
2952 error
= lookup_fast(nd
, path
, &inode
);
2959 BUG_ON(nd
->inode
!= dir
->d_inode
);
2961 /* create side of things */
2963 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
2964 * has been cleared when we got to the last component we are
2967 error
= complete_walk(nd
);
2971 audit_inode(name
, dir
, LOOKUP_PARENT
);
2973 /* trailing slashes? */
2974 if (nd
->last
.name
[nd
->last
.len
])
2979 if (op
->open_flag
& (O_CREAT
| O_TRUNC
| O_WRONLY
| O_RDWR
)) {
2980 error
= mnt_want_write(nd
->path
.mnt
);
2984 * do _not_ fail yet - we might not need that or fail with
2985 * a different error; let lookup_open() decide; we'll be
2986 * dropping this one anyway.
2989 mutex_lock(&dir
->d_inode
->i_mutex
);
2990 error
= lookup_open(nd
, path
, file
, op
, got_write
, opened
);
2991 mutex_unlock(&dir
->d_inode
->i_mutex
);
2997 if ((*opened
& FILE_CREATED
) ||
2998 !S_ISREG(file_inode(file
)->i_mode
))
2999 will_truncate
= false;
3001 audit_inode(name
, file
->f_path
.dentry
, 0);
3005 if (*opened
& FILE_CREATED
) {
3006 /* Don't check for write permission, don't truncate */
3007 open_flag
&= ~O_TRUNC
;
3008 will_truncate
= false;
3009 acc_mode
= MAY_OPEN
;
3010 path_to_nameidata(path
, nd
);
3011 goto finish_open_created
;
3015 * create/update audit record if it already exists.
3017 if (d_is_positive(path
->dentry
))
3018 audit_inode(name
, path
->dentry
, 0);
3021 * If atomic_open() acquired write access it is dropped now due to
3022 * possible mount and symlink following (this might be optimized away if
3026 mnt_drop_write(nd
->path
.mnt
);
3031 if ((open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
))
3034 error
= follow_managed(path
, nd
->flags
);
3039 nd
->flags
|= LOOKUP_JUMPED
;
3041 BUG_ON(nd
->flags
& LOOKUP_RCU
);
3042 inode
= path
->dentry
->d_inode
;
3044 if (d_is_negative(path
->dentry
)) {
3045 path_to_nameidata(path
, nd
);
3049 /* we _can_ be in RCU mode here */
3050 if (should_follow_link(path
->dentry
,
3051 !(open_flag
& O_PATH
) || (nd
->flags
& LOOKUP_FOLLOW
))) {
3052 if (nd
->flags
& LOOKUP_RCU
) {
3053 if (unlikely(nd
->path
.mnt
!= path
->mnt
||
3054 unlazy_walk(nd
, path
->dentry
))) {
3059 BUG_ON(inode
!= path
->dentry
->d_inode
);
3060 if (!(nd
->flags
& LOOKUP_FOLLOW
)) {
3061 path_put_conditional(path
, nd
);
3062 path_put(&nd
->path
);
3068 if ((nd
->flags
& LOOKUP_RCU
) || nd
->path
.mnt
!= path
->mnt
) {
3069 path_to_nameidata(path
, nd
);
3071 save_parent
.dentry
= nd
->path
.dentry
;
3072 save_parent
.mnt
= mntget(path
->mnt
);
3073 nd
->path
.dentry
= path
->dentry
;
3077 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
3079 error
= complete_walk(nd
);
3081 path_put(&save_parent
);
3084 audit_inode(name
, nd
->path
.dentry
, 0);
3086 if ((open_flag
& O_CREAT
) && d_is_dir(nd
->path
.dentry
))
3089 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !d_can_lookup(nd
->path
.dentry
))
3091 if (!d_is_reg(nd
->path
.dentry
))
3092 will_truncate
= false;
3094 if (will_truncate
) {
3095 error
= mnt_want_write(nd
->path
.mnt
);
3100 finish_open_created
:
3101 error
= may_open(&nd
->path
, acc_mode
, open_flag
);
3105 BUG_ON(*opened
& FILE_OPENED
); /* once it's opened, it's opened */
3106 error
= vfs_open(&nd
->path
, file
, current_cred());
3108 *opened
|= FILE_OPENED
;
3110 if (error
== -EOPENSTALE
)
3115 error
= open_check_o_direct(file
);
3118 error
= ima_file_check(file
, op
->acc_mode
, *opened
);
3122 if (will_truncate
) {
3123 error
= handle_truncate(file
);
3129 mnt_drop_write(nd
->path
.mnt
);
3130 path_put(&save_parent
);
3135 path_put_conditional(path
, nd
);
3142 /* If no saved parent or already retried then can't retry */
3143 if (!save_parent
.dentry
|| retried
)
3146 BUG_ON(save_parent
.dentry
!= dir
);
3147 path_put(&nd
->path
);
3148 nd
->path
= save_parent
;
3149 nd
->inode
= dir
->d_inode
;
3150 save_parent
.mnt
= NULL
;
3151 save_parent
.dentry
= NULL
;
3153 mnt_drop_write(nd
->path
.mnt
);
3160 static int do_tmpfile(int dfd
, struct filename
*pathname
,
3161 struct nameidata
*nd
, int flags
,
3162 const struct open_flags
*op
,
3163 struct file
*file
, int *opened
)
3165 static const struct qstr name
= QSTR_INIT("/", 1);
3166 struct dentry
*dentry
, *child
;
3168 int error
= path_lookupat(dfd
, pathname
,
3169 flags
| LOOKUP_DIRECTORY
, nd
);
3170 if (unlikely(error
))
3172 error
= mnt_want_write(nd
->path
.mnt
);
3173 if (unlikely(error
))
3175 /* we want directory to be writable */
3176 error
= inode_permission(nd
->inode
, MAY_WRITE
| MAY_EXEC
);
3179 dentry
= nd
->path
.dentry
;
3180 dir
= dentry
->d_inode
;
3181 if (!dir
->i_op
->tmpfile
) {
3182 error
= -EOPNOTSUPP
;
3185 child
= d_alloc(dentry
, &name
);
3186 if (unlikely(!child
)) {
3190 nd
->flags
&= ~LOOKUP_DIRECTORY
;
3191 nd
->flags
|= op
->intent
;
3192 dput(nd
->path
.dentry
);
3193 nd
->path
.dentry
= child
;
3194 error
= dir
->i_op
->tmpfile(dir
, nd
->path
.dentry
, op
->mode
);
3197 audit_inode(pathname
, nd
->path
.dentry
, 0);
3198 /* Don't check for other permissions, the inode was just created */
3199 error
= may_open(&nd
->path
, MAY_OPEN
, op
->open_flag
);
3202 file
->f_path
.mnt
= nd
->path
.mnt
;
3203 error
= finish_open(file
, nd
->path
.dentry
, NULL
, opened
);
3206 error
= open_check_o_direct(file
);
3209 } else if (!(op
->open_flag
& O_EXCL
)) {
3210 struct inode
*inode
= file_inode(file
);
3211 spin_lock(&inode
->i_lock
);
3212 inode
->i_state
|= I_LINKABLE
;
3213 spin_unlock(&inode
->i_lock
);
3216 mnt_drop_write(nd
->path
.mnt
);
3218 path_put(&nd
->path
);
3222 static struct file
*path_openat(int dfd
, struct filename
*pathname
,
3223 struct nameidata
*nd
, const struct open_flags
*op
, int flags
)
3230 file
= get_empty_filp();
3234 file
->f_flags
= op
->open_flag
;
3236 if (unlikely(file
->f_flags
& __O_TMPFILE
)) {
3237 error
= do_tmpfile(dfd
, pathname
, nd
, flags
, op
, file
, &opened
);
3241 error
= path_init(dfd
, pathname
, flags
, nd
);
3242 if (unlikely(error
))
3245 error
= do_last(nd
, &path
, file
, op
, &opened
, pathname
);
3246 while (unlikely(error
> 0)) { /* trailing symlink */
3247 struct path link
= path
;
3249 error
= may_follow_link(&link
, nd
);
3250 if (unlikely(error
))
3252 nd
->flags
|= LOOKUP_PARENT
;
3253 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
3254 error
= follow_link(&link
, nd
, &cookie
);
3255 if (unlikely(error
))
3257 error
= do_last(nd
, &path
, file
, op
, &opened
, pathname
);
3258 put_link(nd
, &link
, cookie
);
3263 if (!(opened
& FILE_OPENED
)) {
3267 if (unlikely(error
)) {
3268 if (error
== -EOPENSTALE
) {
3269 if (flags
& LOOKUP_RCU
)
3274 file
= ERR_PTR(error
);
3279 struct file
*do_filp_open(int dfd
, struct filename
*pathname
,
3280 const struct open_flags
*op
)
3282 struct nameidata nd
;
3283 int flags
= op
->lookup_flags
;
3286 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
| LOOKUP_RCU
);
3287 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
3288 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
);
3289 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
3290 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
| LOOKUP_REVAL
);
3294 struct file
*do_file_open_root(struct dentry
*dentry
, struct vfsmount
*mnt
,
3295 const char *name
, const struct open_flags
*op
)
3297 struct nameidata nd
;
3299 struct filename
*filename
;
3300 int flags
= op
->lookup_flags
| LOOKUP_ROOT
;
3303 nd
.root
.dentry
= dentry
;
3305 if (d_is_symlink(dentry
) && op
->intent
& LOOKUP_OPEN
)
3306 return ERR_PTR(-ELOOP
);
3308 filename
= getname_kernel(name
);
3309 if (unlikely(IS_ERR(filename
)))
3310 return ERR_CAST(filename
);
3312 file
= path_openat(-1, filename
, &nd
, op
, flags
| LOOKUP_RCU
);
3313 if (unlikely(file
== ERR_PTR(-ECHILD
)))
3314 file
= path_openat(-1, filename
, &nd
, op
, flags
);
3315 if (unlikely(file
== ERR_PTR(-ESTALE
)))
3316 file
= path_openat(-1, filename
, &nd
, op
, flags
| LOOKUP_REVAL
);
3321 static struct dentry
*filename_create(int dfd
, struct filename
*name
,
3322 struct path
*path
, unsigned int lookup_flags
)
3324 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
3325 struct nameidata nd
;
3328 bool is_dir
= (lookup_flags
& LOOKUP_DIRECTORY
);
3331 * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
3332 * other flags passed in are ignored!
3334 lookup_flags
&= LOOKUP_REVAL
;
3336 error
= filename_lookup(dfd
, name
, LOOKUP_PARENT
|lookup_flags
, &nd
);
3338 return ERR_PTR(error
);
3341 * Yucky last component or no last component at all?
3342 * (foo/., foo/.., /////)
3344 if (nd
.last_type
!= LAST_NORM
)
3346 nd
.flags
&= ~LOOKUP_PARENT
;
3347 nd
.flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
3349 /* don't fail immediately if it's r/o, at least try to report other errors */
3350 err2
= mnt_want_write(nd
.path
.mnt
);
3352 * Do the final lookup.
3354 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3355 dentry
= lookup_hash(&nd
);
3360 if (d_is_positive(dentry
))
3364 * Special case - lookup gave negative, but... we had foo/bar/
3365 * From the vfs_mknod() POV we just have a negative dentry -
3366 * all is fine. Let's be bastards - you had / on the end, you've
3367 * been asking for (non-existent) directory. -ENOENT for you.
3369 if (unlikely(!is_dir
&& nd
.last
.name
[nd
.last
.len
])) {
3373 if (unlikely(err2
)) {
3381 dentry
= ERR_PTR(error
);
3383 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
3385 mnt_drop_write(nd
.path
.mnt
);
3391 struct dentry
*kern_path_create(int dfd
, const char *pathname
,
3392 struct path
*path
, unsigned int lookup_flags
)
3394 struct filename
*filename
= getname_kernel(pathname
);
3397 if (IS_ERR(filename
))
3398 return ERR_CAST(filename
);
3399 res
= filename_create(dfd
, filename
, path
, lookup_flags
);
3403 EXPORT_SYMBOL(kern_path_create
);
3405 void done_path_create(struct path
*path
, struct dentry
*dentry
)
3408 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
3409 mnt_drop_write(path
->mnt
);
3412 EXPORT_SYMBOL(done_path_create
);
3414 struct dentry
*user_path_create(int dfd
, const char __user
*pathname
,
3415 struct path
*path
, unsigned int lookup_flags
)
3417 struct filename
*tmp
= getname(pathname
);
3420 return ERR_CAST(tmp
);
3421 res
= filename_create(dfd
, tmp
, path
, lookup_flags
);
3425 EXPORT_SYMBOL(user_path_create
);
3427 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3429 int error
= may_create(dir
, dentry
);
3434 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
3437 if (!dir
->i_op
->mknod
)
3440 error
= devcgroup_inode_mknod(mode
, dev
);
3444 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
3448 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
3450 fsnotify_create(dir
, dentry
);
3453 EXPORT_SYMBOL(vfs_mknod
);
3455 static int may_mknod(umode_t mode
)
3457 switch (mode
& S_IFMT
) {
3463 case 0: /* zero mode translates to S_IFREG */
3472 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
3475 struct dentry
*dentry
;
3478 unsigned int lookup_flags
= 0;
3480 error
= may_mknod(mode
);
3484 dentry
= user_path_create(dfd
, filename
, &path
, lookup_flags
);
3486 return PTR_ERR(dentry
);
3488 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3489 mode
&= ~current_umask();
3490 error
= security_path_mknod(&path
, dentry
, mode
, dev
);
3493 switch (mode
& S_IFMT
) {
3494 case 0: case S_IFREG
:
3495 error
= vfs_create(path
.dentry
->d_inode
,dentry
,mode
,true);
3497 case S_IFCHR
: case S_IFBLK
:
3498 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,
3499 new_decode_dev(dev
));
3501 case S_IFIFO
: case S_IFSOCK
:
3502 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,0);
3506 done_path_create(&path
, dentry
);
3507 if (retry_estale(error
, lookup_flags
)) {
3508 lookup_flags
|= LOOKUP_REVAL
;
3514 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
3516 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
3519 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
3521 int error
= may_create(dir
, dentry
);
3522 unsigned max_links
= dir
->i_sb
->s_max_links
;
3527 if (!dir
->i_op
->mkdir
)
3530 mode
&= (S_IRWXUGO
|S_ISVTX
);
3531 error
= security_inode_mkdir(dir
, dentry
, mode
);
3535 if (max_links
&& dir
->i_nlink
>= max_links
)
3538 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
3540 fsnotify_mkdir(dir
, dentry
);
3543 EXPORT_SYMBOL(vfs_mkdir
);
3545 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, umode_t
, mode
)
3547 struct dentry
*dentry
;
3550 unsigned int lookup_flags
= LOOKUP_DIRECTORY
;
3553 dentry
= user_path_create(dfd
, pathname
, &path
, lookup_flags
);
3555 return PTR_ERR(dentry
);
3557 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3558 mode
&= ~current_umask();
3559 error
= security_path_mkdir(&path
, dentry
, mode
);
3561 error
= vfs_mkdir(path
.dentry
->d_inode
, dentry
, mode
);
3562 done_path_create(&path
, dentry
);
3563 if (retry_estale(error
, lookup_flags
)) {
3564 lookup_flags
|= LOOKUP_REVAL
;
3570 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, umode_t
, mode
)
3572 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
3576 * The dentry_unhash() helper will try to drop the dentry early: we
3577 * should have a usage count of 1 if we're the only user of this
3578 * dentry, and if that is true (possibly after pruning the dcache),
3579 * then we drop the dentry now.
3581 * A low-level filesystem can, if it choses, legally
3584 * if (!d_unhashed(dentry))
3587 * if it cannot handle the case of removing a directory
3588 * that is still in use by something else..
3590 void dentry_unhash(struct dentry
*dentry
)
3592 shrink_dcache_parent(dentry
);
3593 spin_lock(&dentry
->d_lock
);
3594 if (dentry
->d_lockref
.count
== 1)
3596 spin_unlock(&dentry
->d_lock
);
3598 EXPORT_SYMBOL(dentry_unhash
);
3600 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
3602 int error
= may_delete(dir
, dentry
, 1);
3607 if (!dir
->i_op
->rmdir
)
3611 mutex_lock(&dentry
->d_inode
->i_mutex
);
3614 if (is_local_mountpoint(dentry
))
3617 error
= security_inode_rmdir(dir
, dentry
);
3621 shrink_dcache_parent(dentry
);
3622 error
= dir
->i_op
->rmdir(dir
, dentry
);
3626 dentry
->d_inode
->i_flags
|= S_DEAD
;
3628 detach_mounts(dentry
);
3631 mutex_unlock(&dentry
->d_inode
->i_mutex
);
3637 EXPORT_SYMBOL(vfs_rmdir
);
3639 static long do_rmdir(int dfd
, const char __user
*pathname
)
3642 struct filename
*name
;
3643 struct dentry
*dentry
;
3644 struct nameidata nd
;
3645 unsigned int lookup_flags
= 0;
3647 name
= user_path_parent(dfd
, pathname
, &nd
, lookup_flags
);
3649 return PTR_ERR(name
);
3651 switch(nd
.last_type
) {
3663 nd
.flags
&= ~LOOKUP_PARENT
;
3664 error
= mnt_want_write(nd
.path
.mnt
);
3668 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3669 dentry
= lookup_hash(&nd
);
3670 error
= PTR_ERR(dentry
);
3673 if (!dentry
->d_inode
) {
3677 error
= security_path_rmdir(&nd
.path
, dentry
);
3680 error
= vfs_rmdir(nd
.path
.dentry
->d_inode
, dentry
);
3684 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
3685 mnt_drop_write(nd
.path
.mnt
);
3689 if (retry_estale(error
, lookup_flags
)) {
3690 lookup_flags
|= LOOKUP_REVAL
;
3696 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
3698 return do_rmdir(AT_FDCWD
, pathname
);
3702 * vfs_unlink - unlink a filesystem object
3703 * @dir: parent directory
3705 * @delegated_inode: returns victim inode, if the inode is delegated.
3707 * The caller must hold dir->i_mutex.
3709 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
3710 * return a reference to the inode in delegated_inode. The caller
3711 * should then break the delegation on that inode and retry. Because
3712 * breaking a delegation may take a long time, the caller should drop
3713 * dir->i_mutex before doing so.
3715 * Alternatively, a caller may pass NULL for delegated_inode. This may
3716 * be appropriate for callers that expect the underlying filesystem not
3717 * to be NFS exported.
3719 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
, struct inode
**delegated_inode
)
3721 struct inode
*target
= dentry
->d_inode
;
3722 int error
= may_delete(dir
, dentry
, 0);
3727 if (!dir
->i_op
->unlink
)
3730 mutex_lock(&target
->i_mutex
);
3731 if (is_local_mountpoint(dentry
))
3734 error
= security_inode_unlink(dir
, dentry
);
3736 error
= try_break_deleg(target
, delegated_inode
);
3739 error
= dir
->i_op
->unlink(dir
, dentry
);
3742 detach_mounts(dentry
);
3747 mutex_unlock(&target
->i_mutex
);
3749 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
3750 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
3751 fsnotify_link_count(target
);
3757 EXPORT_SYMBOL(vfs_unlink
);
3760 * Make sure that the actual truncation of the file will occur outside its
3761 * directory's i_mutex. Truncate can take a long time if there is a lot of
3762 * writeout happening, and we don't want to prevent access to the directory
3763 * while waiting on the I/O.
3765 static long do_unlinkat(int dfd
, const char __user
*pathname
)
3768 struct filename
*name
;
3769 struct dentry
*dentry
;
3770 struct nameidata nd
;
3771 struct inode
*inode
= NULL
;
3772 struct inode
*delegated_inode
= NULL
;
3773 unsigned int lookup_flags
= 0;
3775 name
= user_path_parent(dfd
, pathname
, &nd
, lookup_flags
);
3777 return PTR_ERR(name
);
3780 if (nd
.last_type
!= LAST_NORM
)
3783 nd
.flags
&= ~LOOKUP_PARENT
;
3784 error
= mnt_want_write(nd
.path
.mnt
);
3788 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3789 dentry
= lookup_hash(&nd
);
3790 error
= PTR_ERR(dentry
);
3791 if (!IS_ERR(dentry
)) {
3792 /* Why not before? Because we want correct error value */
3793 if (nd
.last
.name
[nd
.last
.len
])
3795 inode
= dentry
->d_inode
;
3796 if (d_is_negative(dentry
))
3799 error
= security_path_unlink(&nd
.path
, dentry
);
3802 error
= vfs_unlink(nd
.path
.dentry
->d_inode
, dentry
, &delegated_inode
);
3806 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
3808 iput(inode
); /* truncate the inode here */
3810 if (delegated_inode
) {
3811 error
= break_deleg_wait(&delegated_inode
);
3815 mnt_drop_write(nd
.path
.mnt
);
3819 if (retry_estale(error
, lookup_flags
)) {
3820 lookup_flags
|= LOOKUP_REVAL
;
3827 if (d_is_negative(dentry
))
3829 else if (d_is_dir(dentry
))
3836 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
3838 if ((flag
& ~AT_REMOVEDIR
) != 0)
3841 if (flag
& AT_REMOVEDIR
)
3842 return do_rmdir(dfd
, pathname
);
3844 return do_unlinkat(dfd
, pathname
);
3847 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
3849 return do_unlinkat(AT_FDCWD
, pathname
);
3852 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
3854 int error
= may_create(dir
, dentry
);
3859 if (!dir
->i_op
->symlink
)
3862 error
= security_inode_symlink(dir
, dentry
, oldname
);
3866 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
3868 fsnotify_create(dir
, dentry
);
3871 EXPORT_SYMBOL(vfs_symlink
);
3873 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
3874 int, newdfd
, const char __user
*, newname
)
3877 struct filename
*from
;
3878 struct dentry
*dentry
;
3880 unsigned int lookup_flags
= 0;
3882 from
= getname(oldname
);
3884 return PTR_ERR(from
);
3886 dentry
= user_path_create(newdfd
, newname
, &path
, lookup_flags
);
3887 error
= PTR_ERR(dentry
);
3891 error
= security_path_symlink(&path
, dentry
, from
->name
);
3893 error
= vfs_symlink(path
.dentry
->d_inode
, dentry
, from
->name
);
3894 done_path_create(&path
, dentry
);
3895 if (retry_estale(error
, lookup_flags
)) {
3896 lookup_flags
|= LOOKUP_REVAL
;
3904 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
3906 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
3910 * vfs_link - create a new link
3911 * @old_dentry: object to be linked
3913 * @new_dentry: where to create the new link
3914 * @delegated_inode: returns inode needing a delegation break
3916 * The caller must hold dir->i_mutex
3918 * If vfs_link discovers a delegation on the to-be-linked file in need
3919 * of breaking, it will return -EWOULDBLOCK and return a reference to the
3920 * inode in delegated_inode. The caller should then break the delegation
3921 * and retry. Because breaking a delegation may take a long time, the
3922 * caller should drop the i_mutex before doing so.
3924 * Alternatively, a caller may pass NULL for delegated_inode. This may
3925 * be appropriate for callers that expect the underlying filesystem not
3926 * to be NFS exported.
3928 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
, struct inode
**delegated_inode
)
3930 struct inode
*inode
= old_dentry
->d_inode
;
3931 unsigned max_links
= dir
->i_sb
->s_max_links
;
3937 error
= may_create(dir
, new_dentry
);
3941 if (dir
->i_sb
!= inode
->i_sb
)
3945 * A link to an append-only or immutable file cannot be created.
3947 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
3949 if (!dir
->i_op
->link
)
3951 if (S_ISDIR(inode
->i_mode
))
3954 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
3958 mutex_lock(&inode
->i_mutex
);
3959 /* Make sure we don't allow creating hardlink to an unlinked file */
3960 if (inode
->i_nlink
== 0 && !(inode
->i_state
& I_LINKABLE
))
3962 else if (max_links
&& inode
->i_nlink
>= max_links
)
3965 error
= try_break_deleg(inode
, delegated_inode
);
3967 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
3970 if (!error
&& (inode
->i_state
& I_LINKABLE
)) {
3971 spin_lock(&inode
->i_lock
);
3972 inode
->i_state
&= ~I_LINKABLE
;
3973 spin_unlock(&inode
->i_lock
);
3975 mutex_unlock(&inode
->i_mutex
);
3977 fsnotify_link(dir
, inode
, new_dentry
);
3980 EXPORT_SYMBOL(vfs_link
);
3983 * Hardlinks are often used in delicate situations. We avoid
3984 * security-related surprises by not following symlinks on the
3987 * We don't follow them on the oldname either to be compatible
3988 * with linux 2.0, and to avoid hard-linking to directories
3989 * and other special files. --ADM
3991 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
3992 int, newdfd
, const char __user
*, newname
, int, flags
)
3994 struct dentry
*new_dentry
;
3995 struct path old_path
, new_path
;
3996 struct inode
*delegated_inode
= NULL
;
4000 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0)
4003 * To use null names we require CAP_DAC_READ_SEARCH
4004 * This ensures that not everyone will be able to create
4005 * handlink using the passed filedescriptor.
4007 if (flags
& AT_EMPTY_PATH
) {
4008 if (!capable(CAP_DAC_READ_SEARCH
))
4013 if (flags
& AT_SYMLINK_FOLLOW
)
4014 how
|= LOOKUP_FOLLOW
;
4016 error
= user_path_at(olddfd
, oldname
, how
, &old_path
);
4020 new_dentry
= user_path_create(newdfd
, newname
, &new_path
,
4021 (how
& LOOKUP_REVAL
));
4022 error
= PTR_ERR(new_dentry
);
4023 if (IS_ERR(new_dentry
))
4027 if (old_path
.mnt
!= new_path
.mnt
)
4029 error
= may_linkat(&old_path
);
4030 if (unlikely(error
))
4032 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
4035 error
= vfs_link(old_path
.dentry
, new_path
.dentry
->d_inode
, new_dentry
, &delegated_inode
);
4037 done_path_create(&new_path
, new_dentry
);
4038 if (delegated_inode
) {
4039 error
= break_deleg_wait(&delegated_inode
);
4041 path_put(&old_path
);
4045 if (retry_estale(error
, how
)) {
4046 path_put(&old_path
);
4047 how
|= LOOKUP_REVAL
;
4051 path_put(&old_path
);
4056 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
4058 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4062 * vfs_rename - rename a filesystem object
4063 * @old_dir: parent of source
4064 * @old_dentry: source
4065 * @new_dir: parent of destination
4066 * @new_dentry: destination
4067 * @delegated_inode: returns an inode needing a delegation break
4068 * @flags: rename flags
4070 * The caller must hold multiple mutexes--see lock_rename()).
4072 * If vfs_rename discovers a delegation in need of breaking at either
4073 * the source or destination, it will return -EWOULDBLOCK and return a
4074 * reference to the inode in delegated_inode. The caller should then
4075 * break the delegation and retry. Because breaking a delegation may
4076 * take a long time, the caller should drop all locks before doing
4079 * Alternatively, a caller may pass NULL for delegated_inode. This may
4080 * be appropriate for callers that expect the underlying filesystem not
4081 * to be NFS exported.
4083 * The worst of all namespace operations - renaming directory. "Perverted"
4084 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4086 * a) we can get into loop creation.
4087 * b) race potential - two innocent renames can create a loop together.
4088 * That's where 4.4 screws up. Current fix: serialization on
4089 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
4091 * c) we have to lock _four_ objects - parents and victim (if it exists),
4092 * and source (if it is not a directory).
4093 * And that - after we got ->i_mutex on parents (until then we don't know
4094 * whether the target exists). Solution: try to be smart with locking
4095 * order for inodes. We rely on the fact that tree topology may change
4096 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
4097 * move will be locked. Thus we can rank directories by the tree
4098 * (ancestors first) and rank all non-directories after them.
4099 * That works since everybody except rename does "lock parent, lookup,
4100 * lock child" and rename is under ->s_vfs_rename_mutex.
4101 * HOWEVER, it relies on the assumption that any object with ->lookup()
4102 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4103 * we'd better make sure that there's no link(2) for them.
4104 * d) conversion from fhandle to dentry may come in the wrong moment - when
4105 * we are removing the target. Solution: we will have to grab ->i_mutex
4106 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
4107 * ->i_mutex on parents, which works but leads to some truly excessive
4110 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
4111 struct inode
*new_dir
, struct dentry
*new_dentry
,
4112 struct inode
**delegated_inode
, unsigned int flags
)
4115 bool is_dir
= d_is_dir(old_dentry
);
4116 const unsigned char *old_name
;
4117 struct inode
*source
= old_dentry
->d_inode
;
4118 struct inode
*target
= new_dentry
->d_inode
;
4119 bool new_is_dir
= false;
4120 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
4122 if (source
== target
)
4125 error
= may_delete(old_dir
, old_dentry
, is_dir
);
4130 error
= may_create(new_dir
, new_dentry
);
4132 new_is_dir
= d_is_dir(new_dentry
);
4134 if (!(flags
& RENAME_EXCHANGE
))
4135 error
= may_delete(new_dir
, new_dentry
, is_dir
);
4137 error
= may_delete(new_dir
, new_dentry
, new_is_dir
);
4142 if (!old_dir
->i_op
->rename
&& !old_dir
->i_op
->rename2
)
4145 if (flags
&& !old_dir
->i_op
->rename2
)
4149 * If we are going to change the parent - check write permissions,
4150 * we'll need to flip '..'.
4152 if (new_dir
!= old_dir
) {
4154 error
= inode_permission(source
, MAY_WRITE
);
4158 if ((flags
& RENAME_EXCHANGE
) && new_is_dir
) {
4159 error
= inode_permission(target
, MAY_WRITE
);
4165 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
,
4170 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
4172 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4173 lock_two_nondirectories(source
, target
);
4175 mutex_lock(&target
->i_mutex
);
4178 if (is_local_mountpoint(old_dentry
) || is_local_mountpoint(new_dentry
))
4181 if (max_links
&& new_dir
!= old_dir
) {
4183 if (is_dir
&& !new_is_dir
&& new_dir
->i_nlink
>= max_links
)
4185 if ((flags
& RENAME_EXCHANGE
) && !is_dir
&& new_is_dir
&&
4186 old_dir
->i_nlink
>= max_links
)
4189 if (is_dir
&& !(flags
& RENAME_EXCHANGE
) && target
)
4190 shrink_dcache_parent(new_dentry
);
4192 error
= try_break_deleg(source
, delegated_inode
);
4196 if (target
&& !new_is_dir
) {
4197 error
= try_break_deleg(target
, delegated_inode
);
4201 if (!old_dir
->i_op
->rename2
) {
4202 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
,
4203 new_dir
, new_dentry
);
4205 WARN_ON(old_dir
->i_op
->rename
!= NULL
);
4206 error
= old_dir
->i_op
->rename2(old_dir
, old_dentry
,
4207 new_dir
, new_dentry
, flags
);
4212 if (!(flags
& RENAME_EXCHANGE
) && target
) {
4214 target
->i_flags
|= S_DEAD
;
4215 dont_mount(new_dentry
);
4216 detach_mounts(new_dentry
);
4218 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
)) {
4219 if (!(flags
& RENAME_EXCHANGE
))
4220 d_move(old_dentry
, new_dentry
);
4222 d_exchange(old_dentry
, new_dentry
);
4225 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4226 unlock_two_nondirectories(source
, target
);
4228 mutex_unlock(&target
->i_mutex
);
4231 fsnotify_move(old_dir
, new_dir
, old_name
, is_dir
,
4232 !(flags
& RENAME_EXCHANGE
) ? target
: NULL
, old_dentry
);
4233 if (flags
& RENAME_EXCHANGE
) {
4234 fsnotify_move(new_dir
, old_dir
, old_dentry
->d_name
.name
,
4235 new_is_dir
, NULL
, new_dentry
);
4238 fsnotify_oldname_free(old_name
);
4242 EXPORT_SYMBOL(vfs_rename
);
4244 SYSCALL_DEFINE5(renameat2
, int, olddfd
, const char __user
*, oldname
,
4245 int, newdfd
, const char __user
*, newname
, unsigned int, flags
)
4247 struct dentry
*old_dir
, *new_dir
;
4248 struct dentry
*old_dentry
, *new_dentry
;
4249 struct dentry
*trap
;
4250 struct nameidata oldnd
, newnd
;
4251 struct inode
*delegated_inode
= NULL
;
4252 struct filename
*from
;
4253 struct filename
*to
;
4254 unsigned int lookup_flags
= 0;
4255 bool should_retry
= false;
4258 if (flags
& ~(RENAME_NOREPLACE
| RENAME_EXCHANGE
| RENAME_WHITEOUT
))
4261 if ((flags
& (RENAME_NOREPLACE
| RENAME_WHITEOUT
)) &&
4262 (flags
& RENAME_EXCHANGE
))
4265 if ((flags
& RENAME_WHITEOUT
) && !capable(CAP_MKNOD
))
4269 from
= user_path_parent(olddfd
, oldname
, &oldnd
, lookup_flags
);
4271 error
= PTR_ERR(from
);
4275 to
= user_path_parent(newdfd
, newname
, &newnd
, lookup_flags
);
4277 error
= PTR_ERR(to
);
4282 if (oldnd
.path
.mnt
!= newnd
.path
.mnt
)
4285 old_dir
= oldnd
.path
.dentry
;
4287 if (oldnd
.last_type
!= LAST_NORM
)
4290 new_dir
= newnd
.path
.dentry
;
4291 if (flags
& RENAME_NOREPLACE
)
4293 if (newnd
.last_type
!= LAST_NORM
)
4296 error
= mnt_want_write(oldnd
.path
.mnt
);
4300 oldnd
.flags
&= ~LOOKUP_PARENT
;
4301 newnd
.flags
&= ~LOOKUP_PARENT
;
4302 if (!(flags
& RENAME_EXCHANGE
))
4303 newnd
.flags
|= LOOKUP_RENAME_TARGET
;
4306 trap
= lock_rename(new_dir
, old_dir
);
4308 old_dentry
= lookup_hash(&oldnd
);
4309 error
= PTR_ERR(old_dentry
);
4310 if (IS_ERR(old_dentry
))
4312 /* source must exist */
4314 if (d_is_negative(old_dentry
))
4316 new_dentry
= lookup_hash(&newnd
);
4317 error
= PTR_ERR(new_dentry
);
4318 if (IS_ERR(new_dentry
))
4321 if ((flags
& RENAME_NOREPLACE
) && d_is_positive(new_dentry
))
4323 if (flags
& RENAME_EXCHANGE
) {
4325 if (d_is_negative(new_dentry
))
4328 if (!d_is_dir(new_dentry
)) {
4330 if (newnd
.last
.name
[newnd
.last
.len
])
4334 /* unless the source is a directory trailing slashes give -ENOTDIR */
4335 if (!d_is_dir(old_dentry
)) {
4337 if (oldnd
.last
.name
[oldnd
.last
.len
])
4339 if (!(flags
& RENAME_EXCHANGE
) && newnd
.last
.name
[newnd
.last
.len
])
4342 /* source should not be ancestor of target */
4344 if (old_dentry
== trap
)
4346 /* target should not be an ancestor of source */
4347 if (!(flags
& RENAME_EXCHANGE
))
4349 if (new_dentry
== trap
)
4352 error
= security_path_rename(&oldnd
.path
, old_dentry
,
4353 &newnd
.path
, new_dentry
, flags
);
4356 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
4357 new_dir
->d_inode
, new_dentry
,
4358 &delegated_inode
, flags
);
4364 unlock_rename(new_dir
, old_dir
);
4365 if (delegated_inode
) {
4366 error
= break_deleg_wait(&delegated_inode
);
4370 mnt_drop_write(oldnd
.path
.mnt
);
4372 if (retry_estale(error
, lookup_flags
))
4373 should_retry
= true;
4374 path_put(&newnd
.path
);
4377 path_put(&oldnd
.path
);
4380 should_retry
= false;
4381 lookup_flags
|= LOOKUP_REVAL
;
4388 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
4389 int, newdfd
, const char __user
*, newname
)
4391 return sys_renameat2(olddfd
, oldname
, newdfd
, newname
, 0);
4394 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
4396 return sys_renameat2(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4399 int vfs_whiteout(struct inode
*dir
, struct dentry
*dentry
)
4401 int error
= may_create(dir
, dentry
);
4405 if (!dir
->i_op
->mknod
)
4408 return dir
->i_op
->mknod(dir
, dentry
,
4409 S_IFCHR
| WHITEOUT_MODE
, WHITEOUT_DEV
);
4411 EXPORT_SYMBOL(vfs_whiteout
);
4413 int readlink_copy(char __user
*buffer
, int buflen
, const char *link
)
4415 int len
= PTR_ERR(link
);
4420 if (len
> (unsigned) buflen
)
4422 if (copy_to_user(buffer
, link
, len
))
4427 EXPORT_SYMBOL(readlink_copy
);
4430 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
4431 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
4432 * using) it for any given inode is up to filesystem.
4434 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4436 struct nameidata nd
;
4441 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
4443 return PTR_ERR(cookie
);
4445 res
= readlink_copy(buffer
, buflen
, nd_get_link(&nd
));
4446 if (dentry
->d_inode
->i_op
->put_link
)
4447 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
4450 EXPORT_SYMBOL(generic_readlink
);
4452 /* get the link contents into pagecache */
4453 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
4457 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
4458 page
= read_mapping_page(mapping
, 0, NULL
);
4463 nd_terminate_link(kaddr
, dentry
->d_inode
->i_size
, PAGE_SIZE
- 1);
4467 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4469 struct page
*page
= NULL
;
4470 int res
= readlink_copy(buffer
, buflen
, page_getlink(dentry
, &page
));
4473 page_cache_release(page
);
4477 EXPORT_SYMBOL(page_readlink
);
4479 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
4481 struct page
*page
= NULL
;
4482 nd_set_link(nd
, page_getlink(dentry
, &page
));
4485 EXPORT_SYMBOL(page_follow_link_light
);
4487 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
4489 struct page
*page
= cookie
;
4493 page_cache_release(page
);
4496 EXPORT_SYMBOL(page_put_link
);
4499 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
4501 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
4503 struct address_space
*mapping
= inode
->i_mapping
;
4508 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
4510 flags
|= AOP_FLAG_NOFS
;
4513 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
4514 flags
, &page
, &fsdata
);
4518 kaddr
= kmap_atomic(page
);
4519 memcpy(kaddr
, symname
, len
-1);
4520 kunmap_atomic(kaddr
);
4522 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
4529 mark_inode_dirty(inode
);
4534 EXPORT_SYMBOL(__page_symlink
);
4536 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
4538 return __page_symlink(inode
, symname
, len
,
4539 !(mapping_gfp_mask(inode
->i_mapping
) & __GFP_FS
));
4541 EXPORT_SYMBOL(page_symlink
);
4543 const struct inode_operations page_symlink_inode_operations
= {
4544 .readlink
= generic_readlink
,
4545 .follow_link
= page_follow_link_light
,
4546 .put_link
= page_put_link
,
4548 EXPORT_SYMBOL(page_symlink_inode_operations
);