4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * Some corrections by tytso.
11 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
14 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
17 #include <linux/init.h>
18 #include <linux/export.h>
19 #include <linux/kernel.h>
20 #include <linux/slab.h>
22 #include <linux/namei.h>
23 #include <linux/pagemap.h>
24 #include <linux/fsnotify.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/ima.h>
28 #include <linux/syscalls.h>
29 #include <linux/mount.h>
30 #include <linux/audit.h>
31 #include <linux/capability.h>
32 #include <linux/file.h>
33 #include <linux/fcntl.h>
34 #include <linux/device_cgroup.h>
35 #include <linux/fs_struct.h>
36 #include <linux/posix_acl.h>
37 #include <linux/hash.h>
38 #include <asm/uaccess.h>
43 /* [Feb-1997 T. Schoebel-Theuer]
44 * Fundamental changes in the pathname lookup mechanisms (namei)
45 * were necessary because of omirr. The reason is that omirr needs
46 * to know the _real_ pathname, not the user-supplied one, in case
47 * of symlinks (and also when transname replacements occur).
49 * The new code replaces the old recursive symlink resolution with
50 * an iterative one (in case of non-nested symlink chains). It does
51 * this with calls to <fs>_follow_link().
52 * As a side effect, dir_namei(), _namei() and follow_link() are now
53 * replaced with a single function lookup_dentry() that can handle all
54 * the special cases of the former code.
56 * With the new dcache, the pathname is stored at each inode, at least as
57 * long as the refcount of the inode is positive. As a side effect, the
58 * size of the dcache depends on the inode cache and thus is dynamic.
60 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
61 * resolution to correspond with current state of the code.
63 * Note that the symlink resolution is not *completely* iterative.
64 * There is still a significant amount of tail- and mid- recursion in
65 * the algorithm. Also, note that <fs>_readlink() is not used in
66 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
67 * may return different results than <fs>_follow_link(). Many virtual
68 * filesystems (including /proc) exhibit this behavior.
71 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
72 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
73 * and the name already exists in form of a symlink, try to create the new
74 * name indicated by the symlink. The old code always complained that the
75 * name already exists, due to not following the symlink even if its target
76 * is nonexistent. The new semantics affects also mknod() and link() when
77 * the name is a symlink pointing to a non-existent name.
79 * I don't know which semantics is the right one, since I have no access
80 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
81 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
82 * "old" one. Personally, I think the new semantics is much more logical.
83 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
84 * file does succeed in both HP-UX and SunOs, but not in Solaris
85 * and in the old Linux semantics.
88 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
89 * semantics. See the comments in "open_namei" and "do_link" below.
91 * [10-Sep-98 Alan Modra] Another symlink change.
94 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
95 * inside the path - always follow.
96 * in the last component in creation/removal/renaming - never follow.
97 * if LOOKUP_FOLLOW passed - follow.
98 * if the pathname has trailing slashes - follow.
99 * otherwise - don't follow.
100 * (applied in that order).
102 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
103 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
104 * During the 2.4 we need to fix the userland stuff depending on it -
105 * hopefully we will be able to get rid of that wart in 2.5. So far only
106 * XEmacs seems to be relying on it...
109 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
110 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
111 * any extra contention...
114 /* In order to reduce some races, while at the same time doing additional
115 * checking and hopefully speeding things up, we copy filenames to the
116 * kernel data space before using them..
118 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
119 * PATH_MAX includes the nul terminator --RR.
122 #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname))
125 getname_flags(const char __user
*filename
, int flags
, int *empty
)
127 struct filename
*result
;
131 result
= audit_reusename(filename
);
135 result
= __getname();
136 if (unlikely(!result
))
137 return ERR_PTR(-ENOMEM
);
140 * First, try to embed the struct filename inside the names_cache
143 kname
= (char *)result
->iname
;
144 result
->name
= kname
;
146 len
= strncpy_from_user(kname
, filename
, EMBEDDED_NAME_MAX
);
147 if (unlikely(len
< 0)) {
153 * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
154 * separate struct filename so we can dedicate the entire
155 * names_cache allocation for the pathname, and re-do the copy from
158 if (unlikely(len
== EMBEDDED_NAME_MAX
)) {
159 const size_t size
= offsetof(struct filename
, iname
[1]);
160 kname
= (char *)result
;
163 * size is chosen that way we to guarantee that
164 * result->iname[0] is within the same object and that
165 * kname can't be equal to result->iname, no matter what.
167 result
= kzalloc(size
, GFP_KERNEL
);
168 if (unlikely(!result
)) {
170 return ERR_PTR(-ENOMEM
);
172 result
->name
= kname
;
173 len
= strncpy_from_user(kname
, filename
, PATH_MAX
);
174 if (unlikely(len
< 0)) {
179 if (unlikely(len
== PATH_MAX
)) {
182 return ERR_PTR(-ENAMETOOLONG
);
187 /* The empty path is special. */
188 if (unlikely(!len
)) {
191 if (!(flags
& LOOKUP_EMPTY
)) {
193 return ERR_PTR(-ENOENT
);
197 result
->uptr
= filename
;
198 result
->aname
= NULL
;
199 audit_getname(result
);
204 getname(const char __user
* filename
)
206 return getname_flags(filename
, 0, NULL
);
210 getname_kernel(const char * filename
)
212 struct filename
*result
;
213 int len
= strlen(filename
) + 1;
215 result
= __getname();
216 if (unlikely(!result
))
217 return ERR_PTR(-ENOMEM
);
219 if (len
<= EMBEDDED_NAME_MAX
) {
220 result
->name
= (char *)result
->iname
;
221 } else if (len
<= PATH_MAX
) {
222 struct filename
*tmp
;
224 tmp
= kmalloc(sizeof(*tmp
), GFP_KERNEL
);
225 if (unlikely(!tmp
)) {
227 return ERR_PTR(-ENOMEM
);
229 tmp
->name
= (char *)result
;
233 return ERR_PTR(-ENAMETOOLONG
);
235 memcpy((char *)result
->name
, filename
, len
);
237 result
->aname
= NULL
;
239 audit_getname(result
);
244 void putname(struct filename
*name
)
246 BUG_ON(name
->refcnt
<= 0);
248 if (--name
->refcnt
> 0)
251 if (name
->name
!= name
->iname
) {
252 __putname(name
->name
);
258 static int check_acl(struct inode
*inode
, int mask
)
260 #ifdef CONFIG_FS_POSIX_ACL
261 struct posix_acl
*acl
;
263 if (mask
& MAY_NOT_BLOCK
) {
264 acl
= get_cached_acl_rcu(inode
, ACL_TYPE_ACCESS
);
267 /* no ->get_acl() calls in RCU mode... */
268 if (acl
== ACL_NOT_CACHED
)
270 return posix_acl_permission(inode
, acl
, mask
& ~MAY_NOT_BLOCK
);
273 acl
= get_acl(inode
, ACL_TYPE_ACCESS
);
277 int error
= posix_acl_permission(inode
, acl
, mask
);
278 posix_acl_release(acl
);
287 * This does the basic permission checking
289 static int acl_permission_check(struct inode
*inode
, int mask
)
291 unsigned int mode
= inode
->i_mode
;
293 if (likely(uid_eq(current_fsuid(), inode
->i_uid
)))
296 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
)) {
297 int error
= check_acl(inode
, mask
);
298 if (error
!= -EAGAIN
)
302 if (in_group_p(inode
->i_gid
))
307 * If the DACs are ok we don't need any capability check.
309 if ((mask
& ~mode
& (MAY_READ
| MAY_WRITE
| MAY_EXEC
)) == 0)
315 * generic_permission - check for access rights on a Posix-like filesystem
316 * @inode: inode to check access rights for
317 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
319 * Used to check for read/write/execute permissions on a file.
320 * We use "fsuid" for this, letting us set arbitrary permissions
321 * for filesystem access without changing the "normal" uids which
322 * are used for other things.
324 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
325 * request cannot be satisfied (eg. requires blocking or too much complexity).
326 * It would then be called again in ref-walk mode.
328 int generic_permission(struct inode
*inode
, int mask
)
333 * Do the basic permission checks.
335 ret
= acl_permission_check(inode
, mask
);
339 if (S_ISDIR(inode
->i_mode
)) {
340 /* DACs are overridable for directories */
341 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_OVERRIDE
))
343 if (!(mask
& MAY_WRITE
))
344 if (capable_wrt_inode_uidgid(inode
,
345 CAP_DAC_READ_SEARCH
))
350 * Read/write DACs are always overridable.
351 * Executable DACs are overridable when there is
352 * at least one exec bit set.
354 if (!(mask
& MAY_EXEC
) || (inode
->i_mode
& S_IXUGO
))
355 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_OVERRIDE
))
359 * Searching includes executable on directories, else just read.
361 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
362 if (mask
== MAY_READ
)
363 if (capable_wrt_inode_uidgid(inode
, CAP_DAC_READ_SEARCH
))
368 EXPORT_SYMBOL(generic_permission
);
371 * We _really_ want to just do "generic_permission()" without
372 * even looking at the inode->i_op values. So we keep a cache
373 * flag in inode->i_opflags, that says "this has not special
374 * permission function, use the fast case".
376 static inline int do_inode_permission(struct inode
*inode
, int mask
)
378 if (unlikely(!(inode
->i_opflags
& IOP_FASTPERM
))) {
379 if (likely(inode
->i_op
->permission
))
380 return inode
->i_op
->permission(inode
, mask
);
382 /* This gets set once for the inode lifetime */
383 spin_lock(&inode
->i_lock
);
384 inode
->i_opflags
|= IOP_FASTPERM
;
385 spin_unlock(&inode
->i_lock
);
387 return generic_permission(inode
, mask
);
391 * __inode_permission - Check for access rights to a given inode
392 * @inode: Inode to check permission on
393 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
395 * Check for read/write/execute permissions on an inode.
397 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
399 * This does not check for a read-only file system. You probably want
400 * inode_permission().
402 int __inode_permission(struct inode
*inode
, int mask
)
406 if (unlikely(mask
& MAY_WRITE
)) {
408 * Nobody gets write access to an immutable file.
410 if (IS_IMMUTABLE(inode
))
414 retval
= do_inode_permission(inode
, mask
);
418 retval
= devcgroup_inode_permission(inode
, mask
);
422 return security_inode_permission(inode
, mask
);
424 EXPORT_SYMBOL(__inode_permission
);
427 * sb_permission - Check superblock-level permissions
428 * @sb: Superblock of inode to check permission on
429 * @inode: Inode to check permission on
430 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
432 * Separate out file-system wide checks from inode-specific permission checks.
434 static int sb_permission(struct super_block
*sb
, struct inode
*inode
, int mask
)
436 if (unlikely(mask
& MAY_WRITE
)) {
437 umode_t mode
= inode
->i_mode
;
439 /* Nobody gets write access to a read-only fs. */
440 if ((sb
->s_flags
& MS_RDONLY
) &&
441 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
448 * inode_permission - Check for access rights to a given inode
449 * @inode: Inode to check permission on
450 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
452 * Check for read/write/execute permissions on an inode. We use fs[ug]id for
453 * this, letting us set arbitrary permissions for filesystem access without
454 * changing the "normal" UIDs which are used for other things.
456 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
458 int inode_permission(struct inode
*inode
, int mask
)
462 retval
= sb_permission(inode
->i_sb
, inode
, mask
);
465 return __inode_permission(inode
, mask
);
467 EXPORT_SYMBOL(inode_permission
);
470 * path_get - get a reference to a path
471 * @path: path to get the reference to
473 * Given a path increment the reference count to the dentry and the vfsmount.
475 void path_get(const struct path
*path
)
480 EXPORT_SYMBOL(path_get
);
483 * path_put - put a reference to a path
484 * @path: path to put the reference to
486 * Given a path decrement the reference count to the dentry and the vfsmount.
488 void path_put(const struct path
*path
)
493 EXPORT_SYMBOL(path_put
);
495 #define EMBEDDED_LEVELS 2
503 struct inode
*inode
; /* path.dentry.d_inode */
513 } *stack
, internal
[EMBEDDED_LEVELS
];
516 static void set_nameidata(struct nameidata
*nd
)
518 nd
->stack
= nd
->internal
;
521 static void restore_nameidata(struct nameidata
*nd
)
523 if (nd
->stack
!= nd
->internal
) {
525 nd
->stack
= nd
->internal
;
529 static int __nd_alloc_stack(struct nameidata
*nd
)
531 struct saved
*p
= kmalloc((MAXSYMLINKS
+ 1) * sizeof(struct saved
),
535 memcpy(p
, nd
->internal
, sizeof(nd
->internal
));
540 static inline int nd_alloc_stack(struct nameidata
*nd
)
542 if (likely(nd
->depth
!= EMBEDDED_LEVELS
))
544 if (likely(nd
->stack
!= nd
->internal
))
546 return __nd_alloc_stack(nd
);
550 * Path walking has 2 modes, rcu-walk and ref-walk (see
551 * Documentation/filesystems/path-lookup.txt). In situations when we can't
552 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
553 * normal reference counts on dentries and vfsmounts to transition to rcu-walk
554 * mode. Refcounts are grabbed at the last known good point before rcu-walk
555 * got stuck, so ref-walk may continue from there. If this is not successful
556 * (eg. a seqcount has changed), then failure is returned and it's up to caller
557 * to restart the path walk from the beginning in ref-walk mode.
561 * unlazy_walk - try to switch to ref-walk mode.
562 * @nd: nameidata pathwalk data
563 * @dentry: child of nd->path.dentry or NULL
564 * Returns: 0 on success, -ECHILD on failure
566 * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
567 * for ref-walk mode. @dentry must be a path found by a do_lookup call on
568 * @nd or NULL. Must be called from rcu-walk context.
570 static int unlazy_walk(struct nameidata
*nd
, struct dentry
*dentry
)
572 struct fs_struct
*fs
= current
->fs
;
573 struct dentry
*parent
= nd
->path
.dentry
;
575 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
578 * After legitimizing the bastards, terminate_walk()
579 * will do the right thing for non-RCU mode, and all our
580 * subsequent exit cases should rcu_read_unlock()
581 * before returning. Do vfsmount first; if dentry
582 * can't be legitimized, just set nd->path.dentry to NULL
583 * and rely on dput(NULL) being a no-op.
585 if (!legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
))
587 nd
->flags
&= ~LOOKUP_RCU
;
589 if (!lockref_get_not_dead(&parent
->d_lockref
)) {
590 nd
->path
.dentry
= NULL
;
595 * For a negative lookup, the lookup sequence point is the parents
596 * sequence point, and it only needs to revalidate the parent dentry.
598 * For a positive lookup, we need to move both the parent and the
599 * dentry from the RCU domain to be properly refcounted. And the
600 * sequence number in the dentry validates *both* dentry counters,
601 * since we checked the sequence number of the parent after we got
602 * the child sequence number. So we know the parent must still
603 * be valid if the child sequence number is still valid.
606 if (read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
608 BUG_ON(nd
->inode
!= parent
->d_inode
);
610 if (!lockref_get_not_dead(&dentry
->d_lockref
))
612 if (read_seqcount_retry(&dentry
->d_seq
, nd
->seq
))
617 * Sequence counts matched. Now make sure that the root is
618 * still valid and get it if required.
620 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
621 spin_lock(&fs
->lock
);
622 if (nd
->root
.mnt
!= fs
->root
.mnt
|| nd
->root
.dentry
!= fs
->root
.dentry
)
623 goto unlock_and_drop_dentry
;
625 spin_unlock(&fs
->lock
);
631 unlock_and_drop_dentry
:
632 spin_unlock(&fs
->lock
);
640 if (!(nd
->flags
& LOOKUP_ROOT
))
645 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
647 return dentry
->d_op
->d_revalidate(dentry
, flags
);
651 * complete_walk - successful completion of path walk
652 * @nd: pointer nameidata
654 * If we had been in RCU mode, drop out of it and legitimize nd->path.
655 * Revalidate the final result, unless we'd already done that during
656 * the path walk or the filesystem doesn't ask for it. Return 0 on
657 * success, -error on failure. In case of failure caller does not
658 * need to drop nd->path.
660 static int complete_walk(struct nameidata
*nd
)
662 struct dentry
*dentry
= nd
->path
.dentry
;
665 if (nd
->flags
& LOOKUP_RCU
) {
666 nd
->flags
&= ~LOOKUP_RCU
;
667 if (!(nd
->flags
& LOOKUP_ROOT
))
670 if (!legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
)) {
674 if (unlikely(!lockref_get_not_dead(&dentry
->d_lockref
))) {
676 mntput(nd
->path
.mnt
);
679 if (read_seqcount_retry(&dentry
->d_seq
, nd
->seq
)) {
682 mntput(nd
->path
.mnt
);
688 if (likely(!(nd
->flags
& LOOKUP_JUMPED
)))
691 if (likely(!(dentry
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)))
694 status
= dentry
->d_op
->d_weak_revalidate(dentry
, nd
->flags
);
705 static __always_inline
void set_root(struct nameidata
*nd
)
707 get_fs_root(current
->fs
, &nd
->root
);
710 static __always_inline
unsigned set_root_rcu(struct nameidata
*nd
)
712 struct fs_struct
*fs
= current
->fs
;
716 seq
= read_seqcount_begin(&fs
->seq
);
718 res
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
719 } while (read_seqcount_retry(&fs
->seq
, seq
));
723 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
726 if (path
->mnt
!= nd
->path
.mnt
)
730 static inline void path_to_nameidata(const struct path
*path
,
731 struct nameidata
*nd
)
733 if (!(nd
->flags
& LOOKUP_RCU
)) {
734 dput(nd
->path
.dentry
);
735 if (nd
->path
.mnt
!= path
->mnt
)
736 mntput(nd
->path
.mnt
);
738 nd
->path
.mnt
= path
->mnt
;
739 nd
->path
.dentry
= path
->dentry
;
743 * Helper to directly jump to a known parsed path from ->follow_link,
744 * caller must have taken a reference to path beforehand.
746 void nd_jump_link(struct nameidata
*nd
, struct path
*path
)
751 nd
->inode
= nd
->path
.dentry
->d_inode
;
752 nd
->flags
|= LOOKUP_JUMPED
;
755 static inline void put_link(struct nameidata
*nd
)
757 struct saved
*last
= nd
->stack
+ nd
->depth
;
758 struct inode
*inode
= last
->link
.dentry
->d_inode
;
759 if (last
->cookie
&& inode
->i_op
->put_link
)
760 inode
->i_op
->put_link(last
->link
.dentry
, last
->cookie
);
761 path_put(&last
->link
);
764 int sysctl_protected_symlinks __read_mostly
= 0;
765 int sysctl_protected_hardlinks __read_mostly
= 0;
768 * may_follow_link - Check symlink following for unsafe situations
769 * @link: The path of the symlink
770 * @nd: nameidata pathwalk data
772 * In the case of the sysctl_protected_symlinks sysctl being enabled,
773 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
774 * in a sticky world-writable directory. This is to protect privileged
775 * processes from failing races against path names that may change out
776 * from under them by way of other users creating malicious symlinks.
777 * It will permit symlinks to be followed only when outside a sticky
778 * world-writable directory, or when the uid of the symlink and follower
779 * match, or when the directory owner matches the symlink's owner.
781 * Returns 0 if following the symlink is allowed, -ve on error.
783 static inline int may_follow_link(struct path
*link
, struct nameidata
*nd
)
785 const struct inode
*inode
;
786 const struct inode
*parent
;
788 if (!sysctl_protected_symlinks
)
791 /* Allowed if owner and follower match. */
792 inode
= link
->dentry
->d_inode
;
793 if (uid_eq(current_cred()->fsuid
, inode
->i_uid
))
796 /* Allowed if parent directory not sticky and world-writable. */
797 parent
= nd
->path
.dentry
->d_inode
;
798 if ((parent
->i_mode
& (S_ISVTX
|S_IWOTH
)) != (S_ISVTX
|S_IWOTH
))
801 /* Allowed if parent directory and link owner match. */
802 if (uid_eq(parent
->i_uid
, inode
->i_uid
))
805 audit_log_link_denied("follow_link", link
);
806 path_put_conditional(link
, nd
);
812 * safe_hardlink_source - Check for safe hardlink conditions
813 * @inode: the source inode to hardlink from
815 * Return false if at least one of the following conditions:
816 * - inode is not a regular file
818 * - inode is setgid and group-exec
819 * - access failure for read and write
821 * Otherwise returns true.
823 static bool safe_hardlink_source(struct inode
*inode
)
825 umode_t mode
= inode
->i_mode
;
827 /* Special files should not get pinned to the filesystem. */
831 /* Setuid files should not get pinned to the filesystem. */
835 /* Executable setgid files should not get pinned to the filesystem. */
836 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
))
839 /* Hardlinking to unreadable or unwritable sources is dangerous. */
840 if (inode_permission(inode
, MAY_READ
| MAY_WRITE
))
847 * may_linkat - Check permissions for creating a hardlink
848 * @link: the source to hardlink from
850 * Block hardlink when all of:
851 * - sysctl_protected_hardlinks enabled
852 * - fsuid does not match inode
853 * - hardlink source is unsafe (see safe_hardlink_source() above)
856 * Returns 0 if successful, -ve on error.
858 static int may_linkat(struct path
*link
)
860 const struct cred
*cred
;
863 if (!sysctl_protected_hardlinks
)
866 cred
= current_cred();
867 inode
= link
->dentry
->d_inode
;
869 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
870 * otherwise, it must be a safe source.
872 if (uid_eq(cred
->fsuid
, inode
->i_uid
) || safe_hardlink_source(inode
) ||
876 audit_log_link_denied("linkat", link
);
880 static __always_inline
881 const char *get_link(struct nameidata
*nd
)
883 struct saved
*last
= nd
->stack
+ nd
->depth
;
884 struct dentry
*dentry
= nd
->link
.dentry
;
885 struct inode
*inode
= dentry
->d_inode
;
889 BUG_ON(nd
->flags
& LOOKUP_RCU
);
891 if (nd
->link
.mnt
== nd
->path
.mnt
)
892 mntget(nd
->link
.mnt
);
894 if (unlikely(current
->total_link_count
>= MAXSYMLINKS
)) {
897 return ERR_PTR(-ELOOP
);
900 last
->link
= nd
->link
;
904 current
->total_link_count
++;
906 touch_atime(&last
->link
);
908 error
= security_inode_follow_link(dentry
);
909 res
= ERR_PTR(error
);
913 nd
->last_type
= LAST_BIND
;
916 res
= inode
->i_op
->follow_link(dentry
, &last
->cookie
, nd
);
920 path_put(&last
->link
);
926 static int follow_up_rcu(struct path
*path
)
928 struct mount
*mnt
= real_mount(path
->mnt
);
929 struct mount
*parent
;
930 struct dentry
*mountpoint
;
932 parent
= mnt
->mnt_parent
;
933 if (&parent
->mnt
== path
->mnt
)
935 mountpoint
= mnt
->mnt_mountpoint
;
936 path
->dentry
= mountpoint
;
937 path
->mnt
= &parent
->mnt
;
942 * follow_up - Find the mountpoint of path's vfsmount
944 * Given a path, find the mountpoint of its source file system.
945 * Replace @path with the path of the mountpoint in the parent mount.
948 * Return 1 if we went up a level and 0 if we were already at the
951 int follow_up(struct path
*path
)
953 struct mount
*mnt
= real_mount(path
->mnt
);
954 struct mount
*parent
;
955 struct dentry
*mountpoint
;
957 read_seqlock_excl(&mount_lock
);
958 parent
= mnt
->mnt_parent
;
960 read_sequnlock_excl(&mount_lock
);
963 mntget(&parent
->mnt
);
964 mountpoint
= dget(mnt
->mnt_mountpoint
);
965 read_sequnlock_excl(&mount_lock
);
967 path
->dentry
= mountpoint
;
969 path
->mnt
= &parent
->mnt
;
972 EXPORT_SYMBOL(follow_up
);
975 * Perform an automount
976 * - return -EISDIR to tell follow_managed() to stop and return the path we
979 static int follow_automount(struct path
*path
, unsigned flags
,
982 struct vfsmount
*mnt
;
985 if (!path
->dentry
->d_op
|| !path
->dentry
->d_op
->d_automount
)
988 /* We don't want to mount if someone's just doing a stat -
989 * unless they're stat'ing a directory and appended a '/' to
992 * We do, however, want to mount if someone wants to open or
993 * create a file of any type under the mountpoint, wants to
994 * traverse through the mountpoint or wants to open the
995 * mounted directory. Also, autofs may mark negative dentries
996 * as being automount points. These will need the attentions
997 * of the daemon to instantiate them before they can be used.
999 if (!(flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
1000 LOOKUP_OPEN
| LOOKUP_CREATE
| LOOKUP_AUTOMOUNT
)) &&
1001 path
->dentry
->d_inode
)
1004 current
->total_link_count
++;
1005 if (current
->total_link_count
>= 40)
1008 mnt
= path
->dentry
->d_op
->d_automount(path
);
1011 * The filesystem is allowed to return -EISDIR here to indicate
1012 * it doesn't want to automount. For instance, autofs would do
1013 * this so that its userspace daemon can mount on this dentry.
1015 * However, we can only permit this if it's a terminal point in
1016 * the path being looked up; if it wasn't then the remainder of
1017 * the path is inaccessible and we should say so.
1019 if (PTR_ERR(mnt
) == -EISDIR
&& (flags
& LOOKUP_PARENT
))
1021 return PTR_ERR(mnt
);
1024 if (!mnt
) /* mount collision */
1027 if (!*need_mntput
) {
1028 /* lock_mount() may release path->mnt on error */
1030 *need_mntput
= true;
1032 err
= finish_automount(mnt
, path
);
1036 /* Someone else made a mount here whilst we were busy */
1041 path
->dentry
= dget(mnt
->mnt_root
);
1050 * Handle a dentry that is managed in some way.
1051 * - Flagged for transit management (autofs)
1052 * - Flagged as mountpoint
1053 * - Flagged as automount point
1055 * This may only be called in refwalk mode.
1057 * Serialization is taken care of in namespace.c
1059 static int follow_managed(struct path
*path
, unsigned flags
)
1061 struct vfsmount
*mnt
= path
->mnt
; /* held by caller, must be left alone */
1063 bool need_mntput
= false;
1066 /* Given that we're not holding a lock here, we retain the value in a
1067 * local variable for each dentry as we look at it so that we don't see
1068 * the components of that value change under us */
1069 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1070 managed
&= DCACHE_MANAGED_DENTRY
,
1071 unlikely(managed
!= 0)) {
1072 /* Allow the filesystem to manage the transit without i_mutex
1074 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1075 BUG_ON(!path
->dentry
->d_op
);
1076 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1077 ret
= path
->dentry
->d_op
->d_manage(path
->dentry
, false);
1082 /* Transit to a mounted filesystem. */
1083 if (managed
& DCACHE_MOUNTED
) {
1084 struct vfsmount
*mounted
= lookup_mnt(path
);
1089 path
->mnt
= mounted
;
1090 path
->dentry
= dget(mounted
->mnt_root
);
1095 /* Something is mounted on this dentry in another
1096 * namespace and/or whatever was mounted there in this
1097 * namespace got unmounted before lookup_mnt() could
1101 /* Handle an automount point */
1102 if (managed
& DCACHE_NEED_AUTOMOUNT
) {
1103 ret
= follow_automount(path
, flags
, &need_mntput
);
1109 /* We didn't change the current path point */
1113 if (need_mntput
&& path
->mnt
== mnt
)
1117 return ret
< 0 ? ret
: need_mntput
;
1120 int follow_down_one(struct path
*path
)
1122 struct vfsmount
*mounted
;
1124 mounted
= lookup_mnt(path
);
1128 path
->mnt
= mounted
;
1129 path
->dentry
= dget(mounted
->mnt_root
);
1134 EXPORT_SYMBOL(follow_down_one
);
1136 static inline int managed_dentry_rcu(struct dentry
*dentry
)
1138 return (dentry
->d_flags
& DCACHE_MANAGE_TRANSIT
) ?
1139 dentry
->d_op
->d_manage(dentry
, true) : 0;
1143 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1144 * we meet a managed dentry that would need blocking.
1146 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
,
1147 struct inode
**inode
)
1150 struct mount
*mounted
;
1152 * Don't forget we might have a non-mountpoint managed dentry
1153 * that wants to block transit.
1155 switch (managed_dentry_rcu(path
->dentry
)) {
1165 if (!d_mountpoint(path
->dentry
))
1166 return !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1168 mounted
= __lookup_mnt(path
->mnt
, path
->dentry
);
1171 path
->mnt
= &mounted
->mnt
;
1172 path
->dentry
= mounted
->mnt
.mnt_root
;
1173 nd
->flags
|= LOOKUP_JUMPED
;
1174 nd
->seq
= read_seqcount_begin(&path
->dentry
->d_seq
);
1176 * Update the inode too. We don't need to re-check the
1177 * dentry sequence number here after this d_inode read,
1178 * because a mount-point is always pinned.
1180 *inode
= path
->dentry
->d_inode
;
1182 return !read_seqretry(&mount_lock
, nd
->m_seq
) &&
1183 !(path
->dentry
->d_flags
& DCACHE_NEED_AUTOMOUNT
);
1186 static int follow_dotdot_rcu(struct nameidata
*nd
)
1188 struct inode
*inode
= nd
->inode
;
1193 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1194 nd
->path
.mnt
== nd
->root
.mnt
) {
1197 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1198 struct dentry
*old
= nd
->path
.dentry
;
1199 struct dentry
*parent
= old
->d_parent
;
1202 inode
= parent
->d_inode
;
1203 seq
= read_seqcount_begin(&parent
->d_seq
);
1204 if (read_seqcount_retry(&old
->d_seq
, nd
->seq
))
1206 nd
->path
.dentry
= parent
;
1210 if (!follow_up_rcu(&nd
->path
))
1212 inode
= nd
->path
.dentry
->d_inode
;
1213 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1215 while (d_mountpoint(nd
->path
.dentry
)) {
1216 struct mount
*mounted
;
1217 mounted
= __lookup_mnt(nd
->path
.mnt
, nd
->path
.dentry
);
1220 nd
->path
.mnt
= &mounted
->mnt
;
1221 nd
->path
.dentry
= mounted
->mnt
.mnt_root
;
1222 inode
= nd
->path
.dentry
->d_inode
;
1223 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1224 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1231 nd
->flags
&= ~LOOKUP_RCU
;
1232 if (!(nd
->flags
& LOOKUP_ROOT
))
1233 nd
->root
.mnt
= NULL
;
1239 * Follow down to the covering mount currently visible to userspace. At each
1240 * point, the filesystem owning that dentry may be queried as to whether the
1241 * caller is permitted to proceed or not.
1243 int follow_down(struct path
*path
)
1248 while (managed
= ACCESS_ONCE(path
->dentry
->d_flags
),
1249 unlikely(managed
& DCACHE_MANAGED_DENTRY
)) {
1250 /* Allow the filesystem to manage the transit without i_mutex
1253 * We indicate to the filesystem if someone is trying to mount
1254 * something here. This gives autofs the chance to deny anyone
1255 * other than its daemon the right to mount on its
1258 * The filesystem may sleep at this point.
1260 if (managed
& DCACHE_MANAGE_TRANSIT
) {
1261 BUG_ON(!path
->dentry
->d_op
);
1262 BUG_ON(!path
->dentry
->d_op
->d_manage
);
1263 ret
= path
->dentry
->d_op
->d_manage(
1264 path
->dentry
, false);
1266 return ret
== -EISDIR
? 0 : ret
;
1269 /* Transit to a mounted filesystem. */
1270 if (managed
& DCACHE_MOUNTED
) {
1271 struct vfsmount
*mounted
= lookup_mnt(path
);
1276 path
->mnt
= mounted
;
1277 path
->dentry
= dget(mounted
->mnt_root
);
1281 /* Don't handle automount points here */
1286 EXPORT_SYMBOL(follow_down
);
1289 * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
1291 static void follow_mount(struct path
*path
)
1293 while (d_mountpoint(path
->dentry
)) {
1294 struct vfsmount
*mounted
= lookup_mnt(path
);
1299 path
->mnt
= mounted
;
1300 path
->dentry
= dget(mounted
->mnt_root
);
1304 static void follow_dotdot(struct nameidata
*nd
)
1310 struct dentry
*old
= nd
->path
.dentry
;
1312 if (nd
->path
.dentry
== nd
->root
.dentry
&&
1313 nd
->path
.mnt
== nd
->root
.mnt
) {
1316 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
1317 /* rare case of legitimate dget_parent()... */
1318 nd
->path
.dentry
= dget_parent(nd
->path
.dentry
);
1322 if (!follow_up(&nd
->path
))
1325 follow_mount(&nd
->path
);
1326 nd
->inode
= nd
->path
.dentry
->d_inode
;
1330 * This looks up the name in dcache, possibly revalidates the old dentry and
1331 * allocates a new one if not found or not valid. In the need_lookup argument
1332 * returns whether i_op->lookup is necessary.
1334 * dir->d_inode->i_mutex must be held
1336 static struct dentry
*lookup_dcache(struct qstr
*name
, struct dentry
*dir
,
1337 unsigned int flags
, bool *need_lookup
)
1339 struct dentry
*dentry
;
1342 *need_lookup
= false;
1343 dentry
= d_lookup(dir
, name
);
1345 if (dentry
->d_flags
& DCACHE_OP_REVALIDATE
) {
1346 error
= d_revalidate(dentry
, flags
);
1347 if (unlikely(error
<= 0)) {
1350 return ERR_PTR(error
);
1352 d_invalidate(dentry
);
1361 dentry
= d_alloc(dir
, name
);
1362 if (unlikely(!dentry
))
1363 return ERR_PTR(-ENOMEM
);
1365 *need_lookup
= true;
1371 * Call i_op->lookup on the dentry. The dentry must be negative and
1374 * dir->d_inode->i_mutex must be held
1376 static struct dentry
*lookup_real(struct inode
*dir
, struct dentry
*dentry
,
1381 /* Don't create child dentry for a dead directory. */
1382 if (unlikely(IS_DEADDIR(dir
))) {
1384 return ERR_PTR(-ENOENT
);
1387 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1388 if (unlikely(old
)) {
1395 static struct dentry
*__lookup_hash(struct qstr
*name
,
1396 struct dentry
*base
, unsigned int flags
)
1399 struct dentry
*dentry
;
1401 dentry
= lookup_dcache(name
, base
, flags
, &need_lookup
);
1405 return lookup_real(base
->d_inode
, dentry
, flags
);
1409 * It's more convoluted than I'd like it to be, but... it's still fairly
1410 * small and for now I'd prefer to have fast path as straight as possible.
1411 * It _is_ time-critical.
1413 static int lookup_fast(struct nameidata
*nd
,
1414 struct path
*path
, struct inode
**inode
)
1416 struct vfsmount
*mnt
= nd
->path
.mnt
;
1417 struct dentry
*dentry
, *parent
= nd
->path
.dentry
;
1423 * Rename seqlock is not required here because in the off chance
1424 * of a false negative due to a concurrent rename, we're going to
1425 * do the non-racy lookup, below.
1427 if (nd
->flags
& LOOKUP_RCU
) {
1430 dentry
= __d_lookup_rcu(parent
, &nd
->last
, &seq
);
1435 * This sequence count validates that the inode matches
1436 * the dentry name information from lookup.
1438 *inode
= dentry
->d_inode
;
1439 negative
= d_is_negative(dentry
);
1440 if (read_seqcount_retry(&dentry
->d_seq
, seq
))
1446 * This sequence count validates that the parent had no
1447 * changes while we did the lookup of the dentry above.
1449 * The memory barrier in read_seqcount_begin of child is
1450 * enough, we can use __read_seqcount_retry here.
1452 if (__read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
1456 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
)) {
1457 status
= d_revalidate(dentry
, nd
->flags
);
1458 if (unlikely(status
<= 0)) {
1459 if (status
!= -ECHILD
)
1465 path
->dentry
= dentry
;
1466 if (likely(__follow_mount_rcu(nd
, path
, inode
)))
1469 if (unlazy_walk(nd
, dentry
))
1472 dentry
= __d_lookup(parent
, &nd
->last
);
1475 if (unlikely(!dentry
))
1478 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
) && need_reval
)
1479 status
= d_revalidate(dentry
, nd
->flags
);
1480 if (unlikely(status
<= 0)) {
1485 d_invalidate(dentry
);
1490 if (unlikely(d_is_negative(dentry
))) {
1495 path
->dentry
= dentry
;
1496 err
= follow_managed(path
, nd
->flags
);
1497 if (unlikely(err
< 0)) {
1498 path_put_conditional(path
, nd
);
1502 nd
->flags
|= LOOKUP_JUMPED
;
1503 *inode
= path
->dentry
->d_inode
;
1510 /* Fast lookup failed, do it the slow way */
1511 static int lookup_slow(struct nameidata
*nd
, struct path
*path
)
1513 struct dentry
*dentry
, *parent
;
1516 parent
= nd
->path
.dentry
;
1517 BUG_ON(nd
->inode
!= parent
->d_inode
);
1519 mutex_lock(&parent
->d_inode
->i_mutex
);
1520 dentry
= __lookup_hash(&nd
->last
, parent
, nd
->flags
);
1521 mutex_unlock(&parent
->d_inode
->i_mutex
);
1523 return PTR_ERR(dentry
);
1524 path
->mnt
= nd
->path
.mnt
;
1525 path
->dentry
= dentry
;
1526 err
= follow_managed(path
, nd
->flags
);
1527 if (unlikely(err
< 0)) {
1528 path_put_conditional(path
, nd
);
1532 nd
->flags
|= LOOKUP_JUMPED
;
1536 static inline int may_lookup(struct nameidata
*nd
)
1538 if (nd
->flags
& LOOKUP_RCU
) {
1539 int err
= inode_permission(nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1542 if (unlazy_walk(nd
, NULL
))
1545 return inode_permission(nd
->inode
, MAY_EXEC
);
1548 static inline int handle_dots(struct nameidata
*nd
, int type
)
1550 if (type
== LAST_DOTDOT
) {
1551 if (nd
->flags
& LOOKUP_RCU
) {
1552 if (follow_dotdot_rcu(nd
))
1560 static void terminate_walk(struct nameidata
*nd
)
1562 if (!(nd
->flags
& LOOKUP_RCU
)) {
1563 path_put(&nd
->path
);
1565 nd
->flags
&= ~LOOKUP_RCU
;
1566 if (!(nd
->flags
& LOOKUP_ROOT
))
1567 nd
->root
.mnt
= NULL
;
1573 * Do we need to follow links? We _really_ want to be able
1574 * to do this check without having to look at inode->i_op,
1575 * so we keep a cache of "no, this doesn't need follow_link"
1576 * for the common case.
1578 static inline int should_follow_link(struct dentry
*dentry
, int follow
)
1580 return unlikely(d_is_symlink(dentry
)) ? follow
: 0;
1583 static int walk_component(struct nameidata
*nd
, int follow
)
1586 struct inode
*inode
;
1589 * "." and ".." are special - ".." especially so because it has
1590 * to be able to know about the current root directory and
1591 * parent relationships.
1593 if (unlikely(nd
->last_type
!= LAST_NORM
))
1594 return handle_dots(nd
, nd
->last_type
);
1595 err
= lookup_fast(nd
, &path
, &inode
);
1596 if (unlikely(err
)) {
1600 err
= lookup_slow(nd
, &path
);
1604 inode
= path
.dentry
->d_inode
;
1606 if (d_is_negative(path
.dentry
))
1610 if (should_follow_link(path
.dentry
, follow
)) {
1611 if (nd
->flags
& LOOKUP_RCU
) {
1612 if (unlikely(nd
->path
.mnt
!= path
.mnt
||
1613 unlazy_walk(nd
, path
.dentry
))) {
1618 BUG_ON(inode
!= path
.dentry
->d_inode
);
1622 path_to_nameidata(&path
, nd
);
1627 path_to_nameidata(&path
, nd
);
1634 * We can do the critical dentry name comparison and hashing
1635 * operations one word at a time, but we are limited to:
1637 * - Architectures with fast unaligned word accesses. We could
1638 * do a "get_unaligned()" if this helps and is sufficiently
1641 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
1642 * do not trap on the (extremely unlikely) case of a page
1643 * crossing operation.
1645 * - Furthermore, we need an efficient 64-bit compile for the
1646 * 64-bit case in order to generate the "number of bytes in
1647 * the final mask". Again, that could be replaced with a
1648 * efficient population count instruction or similar.
1650 #ifdef CONFIG_DCACHE_WORD_ACCESS
1652 #include <asm/word-at-a-time.h>
1656 static inline unsigned int fold_hash(unsigned long hash
)
1658 return hash_64(hash
, 32);
1661 #else /* 32-bit case */
1663 #define fold_hash(x) (x)
1667 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1669 unsigned long a
, mask
;
1670 unsigned long hash
= 0;
1673 a
= load_unaligned_zeropad(name
);
1674 if (len
< sizeof(unsigned long))
1678 name
+= sizeof(unsigned long);
1679 len
-= sizeof(unsigned long);
1683 mask
= bytemask_from_count(len
);
1686 return fold_hash(hash
);
1688 EXPORT_SYMBOL(full_name_hash
);
1691 * Calculate the length and hash of the path component, and
1692 * return the "hash_len" as the result.
1694 static inline u64
hash_name(const char *name
)
1696 unsigned long a
, b
, adata
, bdata
, mask
, hash
, len
;
1697 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
1700 len
= -sizeof(unsigned long);
1702 hash
= (hash
+ a
) * 9;
1703 len
+= sizeof(unsigned long);
1704 a
= load_unaligned_zeropad(name
+len
);
1705 b
= a
^ REPEAT_BYTE('/');
1706 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
1708 adata
= prep_zero_mask(a
, adata
, &constants
);
1709 bdata
= prep_zero_mask(b
, bdata
, &constants
);
1711 mask
= create_zero_mask(adata
| bdata
);
1713 hash
+= a
& zero_bytemask(mask
);
1714 len
+= find_zero(mask
);
1715 return hashlen_create(fold_hash(hash
), len
);
1720 unsigned int full_name_hash(const unsigned char *name
, unsigned int len
)
1722 unsigned long hash
= init_name_hash();
1724 hash
= partial_name_hash(*name
++, hash
);
1725 return end_name_hash(hash
);
1727 EXPORT_SYMBOL(full_name_hash
);
1730 * We know there's a real path component here of at least
1733 static inline u64
hash_name(const char *name
)
1735 unsigned long hash
= init_name_hash();
1736 unsigned long len
= 0, c
;
1738 c
= (unsigned char)*name
;
1741 hash
= partial_name_hash(c
, hash
);
1742 c
= (unsigned char)name
[len
];
1743 } while (c
&& c
!= '/');
1744 return hashlen_create(end_name_hash(hash
), len
);
1751 * This is the basic name resolution function, turning a pathname into
1752 * the final dentry. We expect 'base' to be positive and a directory.
1754 * Returns 0 and nd will have valid dentry and mnt on success.
1755 * Returns error and drops reference to input namei data on failure.
1757 static int link_path_walk(const char *name
, struct nameidata
*nd
)
1767 /* At this point we know we have a real path component. */
1772 err
= may_lookup(nd
);
1776 hash_len
= hash_name(name
);
1779 if (name
[0] == '.') switch (hashlen_len(hash_len
)) {
1781 if (name
[1] == '.') {
1783 nd
->flags
|= LOOKUP_JUMPED
;
1789 if (likely(type
== LAST_NORM
)) {
1790 struct dentry
*parent
= nd
->path
.dentry
;
1791 nd
->flags
&= ~LOOKUP_JUMPED
;
1792 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
1793 struct qstr
this = { { .hash_len
= hash_len
}, .name
= name
};
1794 err
= parent
->d_op
->d_hash(parent
, &this);
1797 hash_len
= this.hash_len
;
1802 nd
->last
.hash_len
= hash_len
;
1803 nd
->last
.name
= name
;
1804 nd
->last_type
= type
;
1806 name
+= hashlen_len(hash_len
);
1810 * If it wasn't NUL, we know it was '/'. Skip that
1811 * slash, and continue until no more slashes.
1815 } while (unlikely(*name
== '/'));
1819 err
= walk_component(nd
, LOOKUP_FOLLOW
);
1827 err
= nd_alloc_stack(nd
);
1828 if (unlikely(err
)) {
1829 path_to_nameidata(&nd
->link
, nd
);
1836 if (unlikely(IS_ERR(s
))) {
1850 path_put(&nd
->path
);
1851 nd
->path
= nd
->root
;
1852 path_get(&nd
->root
);
1853 nd
->flags
|= LOOKUP_JUMPED
;
1854 while (unlikely(*++s
== '/'))
1857 nd
->inode
= nd
->path
.dentry
->d_inode
;
1858 nd
->stack
[nd
->depth
- 1].name
= name
;
1865 if (!d_can_lookup(nd
->path
.dentry
)) {
1872 while (unlikely(nd
->depth
> 1)) {
1879 if (unlikely(nd
->depth
> 1)) {
1880 name
= nd
->stack
[nd
->depth
- 1].name
;
1881 err
= walk_component(nd
, LOOKUP_FOLLOW
);
1890 static int path_init(int dfd
, const struct filename
*name
, unsigned int flags
,
1891 struct nameidata
*nd
)
1894 const char *s
= name
->name
;
1896 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1897 nd
->flags
= flags
| LOOKUP_JUMPED
| LOOKUP_PARENT
;
1900 if (flags
& LOOKUP_ROOT
) {
1901 struct dentry
*root
= nd
->root
.dentry
;
1902 struct inode
*inode
= root
->d_inode
;
1904 if (!d_can_lookup(root
))
1906 retval
= inode_permission(inode
, MAY_EXEC
);
1910 nd
->path
= nd
->root
;
1912 if (flags
& LOOKUP_RCU
) {
1914 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1915 nd
->m_seq
= read_seqbegin(&mount_lock
);
1917 path_get(&nd
->path
);
1922 nd
->root
.mnt
= NULL
;
1924 nd
->m_seq
= read_seqbegin(&mount_lock
);
1926 if (flags
& LOOKUP_RCU
) {
1928 nd
->seq
= set_root_rcu(nd
);
1931 path_get(&nd
->root
);
1933 nd
->path
= nd
->root
;
1934 } else if (dfd
== AT_FDCWD
) {
1935 if (flags
& LOOKUP_RCU
) {
1936 struct fs_struct
*fs
= current
->fs
;
1942 seq
= read_seqcount_begin(&fs
->seq
);
1944 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1945 } while (read_seqcount_retry(&fs
->seq
, seq
));
1947 get_fs_pwd(current
->fs
, &nd
->path
);
1950 /* Caller must check execute permissions on the starting path component */
1951 struct fd f
= fdget_raw(dfd
);
1952 struct dentry
*dentry
;
1957 dentry
= f
.file
->f_path
.dentry
;
1960 if (!d_can_lookup(dentry
)) {
1966 nd
->path
= f
.file
->f_path
;
1967 if (flags
& LOOKUP_RCU
) {
1968 if (f
.flags
& FDPUT_FPUT
)
1970 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
1973 path_get(&nd
->path
);
1978 nd
->inode
= nd
->path
.dentry
->d_inode
;
1979 if (!(flags
& LOOKUP_RCU
))
1981 if (likely(!read_seqcount_retry(&nd
->path
.dentry
->d_seq
, nd
->seq
)))
1983 if (!(nd
->flags
& LOOKUP_ROOT
))
1984 nd
->root
.mnt
= NULL
;
1988 current
->total_link_count
= 0;
1989 return link_path_walk(s
, nd
);
1992 static void path_cleanup(struct nameidata
*nd
)
1994 if (nd
->root
.mnt
&& !(nd
->flags
& LOOKUP_ROOT
)) {
1995 path_put(&nd
->root
);
1996 nd
->root
.mnt
= NULL
;
1998 if (unlikely(nd
->base
))
2002 static int trailing_symlink(struct nameidata
*nd
)
2005 int error
= may_follow_link(&nd
->link
, nd
);
2006 if (unlikely(error
))
2008 nd
->flags
|= LOOKUP_PARENT
;
2010 if (unlikely(IS_ERR(s
)))
2017 path_put(&nd
->path
);
2018 nd
->path
= nd
->root
;
2019 path_get(&nd
->root
);
2020 nd
->flags
|= LOOKUP_JUMPED
;
2022 nd
->inode
= nd
->path
.dentry
->d_inode
;
2023 error
= link_path_walk(s
, nd
);
2024 if (unlikely(error
))
2029 static inline int lookup_last(struct nameidata
*nd
)
2031 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
2032 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2034 nd
->flags
&= ~LOOKUP_PARENT
;
2035 return walk_component(nd
, nd
->flags
& LOOKUP_FOLLOW
);
2038 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2039 static int path_lookupat(int dfd
, const struct filename
*name
,
2040 unsigned int flags
, struct nameidata
*nd
)
2045 * Path walking is largely split up into 2 different synchronisation
2046 * schemes, rcu-walk and ref-walk (explained in
2047 * Documentation/filesystems/path-lookup.txt). These share much of the
2048 * path walk code, but some things particularly setup, cleanup, and
2049 * following mounts are sufficiently divergent that functions are
2050 * duplicated. Typically there is a function foo(), and its RCU
2051 * analogue, foo_rcu().
2053 * -ECHILD is the error number of choice (just to avoid clashes) that
2054 * is returned if some aspect of an rcu-walk fails. Such an error must
2055 * be handled by restarting a traditional ref-walk (which will always
2056 * be able to complete).
2058 err
= path_init(dfd
, name
, flags
, nd
);
2059 if (!err
&& !(flags
& LOOKUP_PARENT
)) {
2060 err
= lookup_last(nd
);
2062 err
= trailing_symlink(nd
);
2065 err
= lookup_last(nd
);
2071 err
= complete_walk(nd
);
2073 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
) {
2074 if (!d_can_lookup(nd
->path
.dentry
)) {
2075 path_put(&nd
->path
);
2084 static int filename_lookup(int dfd
, struct filename
*name
,
2085 unsigned int flags
, struct nameidata
*nd
)
2090 retval
= path_lookupat(dfd
, name
, flags
| LOOKUP_RCU
, nd
);
2092 if (unlikely(retval
== -ECHILD
))
2093 retval
= path_lookupat(dfd
, name
, flags
, nd
);
2094 if (unlikely(retval
== -ESTALE
))
2095 retval
= path_lookupat(dfd
, name
, flags
| LOOKUP_REVAL
, nd
);
2097 if (likely(!retval
))
2098 audit_inode(name
, nd
->path
.dentry
, flags
& LOOKUP_PARENT
);
2099 restore_nameidata(nd
);
2103 /* does lookup, returns the object with parent locked */
2104 struct dentry
*kern_path_locked(const char *name
, struct path
*path
)
2106 struct filename
*filename
= getname_kernel(name
);
2107 struct nameidata nd
;
2111 if (IS_ERR(filename
))
2112 return ERR_CAST(filename
);
2114 err
= filename_lookup(AT_FDCWD
, filename
, LOOKUP_PARENT
, &nd
);
2119 if (nd
.last_type
!= LAST_NORM
) {
2121 d
= ERR_PTR(-EINVAL
);
2124 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2125 d
= __lookup_hash(&nd
.last
, nd
.path
.dentry
, 0);
2127 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2137 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
2139 struct nameidata nd
;
2140 struct filename
*filename
= getname_kernel(name
);
2141 int res
= PTR_ERR(filename
);
2143 if (!IS_ERR(filename
)) {
2144 res
= filename_lookup(AT_FDCWD
, filename
, flags
, &nd
);
2151 EXPORT_SYMBOL(kern_path
);
2154 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2155 * @dentry: pointer to dentry of the base directory
2156 * @mnt: pointer to vfs mount of the base directory
2157 * @name: pointer to file name
2158 * @flags: lookup flags
2159 * @path: pointer to struct path to fill
2161 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
2162 const char *name
, unsigned int flags
,
2165 struct filename
*filename
= getname_kernel(name
);
2166 int err
= PTR_ERR(filename
);
2168 BUG_ON(flags
& LOOKUP_PARENT
);
2170 /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */
2171 if (!IS_ERR(filename
)) {
2172 struct nameidata nd
;
2173 nd
.root
.dentry
= dentry
;
2175 err
= filename_lookup(AT_FDCWD
, filename
,
2176 flags
| LOOKUP_ROOT
, &nd
);
2183 EXPORT_SYMBOL(vfs_path_lookup
);
2186 * lookup_one_len - filesystem helper to lookup single pathname component
2187 * @name: pathname component to lookup
2188 * @base: base directory to lookup from
2189 * @len: maximum length @len should be interpreted to
2191 * Note that this routine is purely a helper for filesystem usage and should
2192 * not be called by generic code.
2194 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2200 WARN_ON_ONCE(!mutex_is_locked(&base
->d_inode
->i_mutex
));
2204 this.hash
= full_name_hash(name
, len
);
2206 return ERR_PTR(-EACCES
);
2208 if (unlikely(name
[0] == '.')) {
2209 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2210 return ERR_PTR(-EACCES
);
2214 c
= *(const unsigned char *)name
++;
2215 if (c
== '/' || c
== '\0')
2216 return ERR_PTR(-EACCES
);
2219 * See if the low-level filesystem might want
2220 * to use its own hash..
2222 if (base
->d_flags
& DCACHE_OP_HASH
) {
2223 int err
= base
->d_op
->d_hash(base
, &this);
2225 return ERR_PTR(err
);
2228 err
= inode_permission(base
->d_inode
, MAY_EXEC
);
2230 return ERR_PTR(err
);
2232 return __lookup_hash(&this, base
, 0);
2234 EXPORT_SYMBOL(lookup_one_len
);
2236 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
2237 struct path
*path
, int *empty
)
2239 struct nameidata nd
;
2240 struct filename
*tmp
= getname_flags(name
, flags
, empty
);
2241 int err
= PTR_ERR(tmp
);
2244 BUG_ON(flags
& LOOKUP_PARENT
);
2246 err
= filename_lookup(dfd
, tmp
, flags
, &nd
);
2254 int user_path_at(int dfd
, const char __user
*name
, unsigned flags
,
2257 return user_path_at_empty(dfd
, name
, flags
, path
, NULL
);
2259 EXPORT_SYMBOL(user_path_at
);
2262 * NB: most callers don't do anything directly with the reference to the
2263 * to struct filename, but the nd->last pointer points into the name string
2264 * allocated by getname. So we must hold the reference to it until all
2265 * path-walking is complete.
2267 static struct filename
*
2268 user_path_parent(int dfd
, const char __user
*path
,
2269 struct path
*parent
,
2274 struct nameidata nd
;
2275 struct filename
*s
= getname(path
);
2278 /* only LOOKUP_REVAL is allowed in extra flags */
2279 flags
&= LOOKUP_REVAL
;
2284 error
= filename_lookup(dfd
, s
, flags
| LOOKUP_PARENT
, &nd
);
2287 return ERR_PTR(error
);
2291 *type
= nd
.last_type
;
2297 * mountpoint_last - look up last component for umount
2298 * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
2299 * @path: pointer to container for result
2301 * This is a special lookup_last function just for umount. In this case, we
2302 * need to resolve the path without doing any revalidation.
2304 * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
2305 * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
2306 * in almost all cases, this lookup will be served out of the dcache. The only
2307 * cases where it won't are if nd->last refers to a symlink or the path is
2308 * bogus and it doesn't exist.
2311 * -error: if there was an error during lookup. This includes -ENOENT if the
2312 * lookup found a negative dentry. The nd->path reference will also be
2315 * 0: if we successfully resolved nd->path and found it to not to be a
2316 * symlink that needs to be followed. "path" will also be populated.
2317 * The nd->path reference will also be put.
2319 * 1: if we successfully resolved nd->last and found it to be a symlink
2320 * that needs to be followed. "path" will be populated with the path
2321 * to the link, and nd->path will *not* be put.
2324 mountpoint_last(struct nameidata
*nd
, struct path
*path
)
2327 struct dentry
*dentry
;
2328 struct dentry
*dir
= nd
->path
.dentry
;
2330 /* If we're in rcuwalk, drop out of it to handle last component */
2331 if (nd
->flags
& LOOKUP_RCU
) {
2332 if (unlazy_walk(nd
, NULL
)) {
2338 nd
->flags
&= ~LOOKUP_PARENT
;
2340 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
2341 error
= handle_dots(nd
, nd
->last_type
);
2344 dentry
= dget(nd
->path
.dentry
);
2348 mutex_lock(&dir
->d_inode
->i_mutex
);
2349 dentry
= d_lookup(dir
, &nd
->last
);
2352 * No cached dentry. Mounted dentries are pinned in the cache,
2353 * so that means that this dentry is probably a symlink or the
2354 * path doesn't actually point to a mounted dentry.
2356 dentry
= d_alloc(dir
, &nd
->last
);
2359 mutex_unlock(&dir
->d_inode
->i_mutex
);
2362 dentry
= lookup_real(dir
->d_inode
, dentry
, nd
->flags
);
2363 error
= PTR_ERR(dentry
);
2364 if (IS_ERR(dentry
)) {
2365 mutex_unlock(&dir
->d_inode
->i_mutex
);
2369 mutex_unlock(&dir
->d_inode
->i_mutex
);
2372 if (d_is_negative(dentry
)) {
2377 path
->dentry
= dentry
;
2378 path
->mnt
= nd
->path
.mnt
;
2379 if (should_follow_link(dentry
, nd
->flags
& LOOKUP_FOLLOW
)) {
2392 * path_mountpoint - look up a path to be umounted
2393 * @dfd: directory file descriptor to start walk from
2394 * @name: full pathname to walk
2395 * @path: pointer to container for result
2396 * @flags: lookup flags
2398 * Look up the given name, but don't attempt to revalidate the last component.
2399 * Returns 0 and "path" will be valid on success; Returns error otherwise.
2402 path_mountpoint(int dfd
, const struct filename
*name
, struct path
*path
,
2403 struct nameidata
*nd
, unsigned int flags
)
2405 int err
= path_init(dfd
, name
, flags
, nd
);
2409 err
= mountpoint_last(nd
, path
);
2411 err
= trailing_symlink(nd
);
2414 err
= mountpoint_last(nd
, path
);
2423 filename_mountpoint(int dfd
, struct filename
*name
, struct path
*path
,
2426 struct nameidata nd
;
2429 return PTR_ERR(name
);
2431 error
= path_mountpoint(dfd
, name
, path
, &nd
, flags
| LOOKUP_RCU
);
2432 if (unlikely(error
== -ECHILD
))
2433 error
= path_mountpoint(dfd
, name
, path
, &nd
, flags
);
2434 if (unlikely(error
== -ESTALE
))
2435 error
= path_mountpoint(dfd
, name
, path
, &nd
, flags
| LOOKUP_REVAL
);
2437 audit_inode(name
, path
->dentry
, 0);
2438 restore_nameidata(&nd
);
2444 * user_path_mountpoint_at - lookup a path from userland in order to umount it
2445 * @dfd: directory file descriptor
2446 * @name: pathname from userland
2447 * @flags: lookup flags
2448 * @path: pointer to container to hold result
2450 * A umount is a special case for path walking. We're not actually interested
2451 * in the inode in this situation, and ESTALE errors can be a problem. We
2452 * simply want track down the dentry and vfsmount attached at the mountpoint
2453 * and avoid revalidating the last component.
2455 * Returns 0 and populates "path" on success.
2458 user_path_mountpoint_at(int dfd
, const char __user
*name
, unsigned int flags
,
2461 return filename_mountpoint(dfd
, getname(name
), path
, flags
);
2465 kern_path_mountpoint(int dfd
, const char *name
, struct path
*path
,
2468 return filename_mountpoint(dfd
, getname_kernel(name
), path
, flags
);
2470 EXPORT_SYMBOL(kern_path_mountpoint
);
2472 int __check_sticky(struct inode
*dir
, struct inode
*inode
)
2474 kuid_t fsuid
= current_fsuid();
2476 if (uid_eq(inode
->i_uid
, fsuid
))
2478 if (uid_eq(dir
->i_uid
, fsuid
))
2480 return !capable_wrt_inode_uidgid(inode
, CAP_FOWNER
);
2482 EXPORT_SYMBOL(__check_sticky
);
2485 * Check whether we can remove a link victim from directory dir, check
2486 * whether the type of victim is right.
2487 * 1. We can't do it if dir is read-only (done in permission())
2488 * 2. We should have write and exec permissions on dir
2489 * 3. We can't remove anything from append-only dir
2490 * 4. We can't do anything with immutable dir (done in permission())
2491 * 5. If the sticky bit on dir is set we should either
2492 * a. be owner of dir, or
2493 * b. be owner of victim, or
2494 * c. have CAP_FOWNER capability
2495 * 6. If the victim is append-only or immutable we can't do antyhing with
2496 * links pointing to it.
2497 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2498 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2499 * 9. We can't remove a root or mountpoint.
2500 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
2501 * nfs_async_unlink().
2503 static int may_delete(struct inode
*dir
, struct dentry
*victim
, bool isdir
)
2505 struct inode
*inode
= victim
->d_inode
;
2508 if (d_is_negative(victim
))
2512 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
2513 audit_inode_child(dir
, victim
, AUDIT_TYPE_CHILD_DELETE
);
2515 error
= inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2521 if (check_sticky(dir
, inode
) || IS_APPEND(inode
) ||
2522 IS_IMMUTABLE(inode
) || IS_SWAPFILE(inode
))
2525 if (!d_is_dir(victim
))
2527 if (IS_ROOT(victim
))
2529 } else if (d_is_dir(victim
))
2531 if (IS_DEADDIR(dir
))
2533 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2538 /* Check whether we can create an object with dentry child in directory
2540 * 1. We can't do it if child already exists (open has special treatment for
2541 * this case, but since we are inlined it's OK)
2542 * 2. We can't do it if dir is read-only (done in permission())
2543 * 3. We should have write and exec permissions on dir
2544 * 4. We can't do it if dir is immutable (done in permission())
2546 static inline int may_create(struct inode
*dir
, struct dentry
*child
)
2548 audit_inode_child(dir
, child
, AUDIT_TYPE_CHILD_CREATE
);
2551 if (IS_DEADDIR(dir
))
2553 return inode_permission(dir
, MAY_WRITE
| MAY_EXEC
);
2557 * p1 and p2 should be directories on the same fs.
2559 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2564 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2568 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2570 p
= d_ancestor(p2
, p1
);
2572 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2573 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2577 p
= d_ancestor(p1
, p2
);
2579 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2580 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
2584 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2585 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT2
);
2588 EXPORT_SYMBOL(lock_rename
);
2590 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
2592 mutex_unlock(&p1
->d_inode
->i_mutex
);
2594 mutex_unlock(&p2
->d_inode
->i_mutex
);
2595 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
2598 EXPORT_SYMBOL(unlock_rename
);
2600 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
2603 int error
= may_create(dir
, dentry
);
2607 if (!dir
->i_op
->create
)
2608 return -EACCES
; /* shouldn't it be ENOSYS? */
2611 error
= security_inode_create(dir
, dentry
, mode
);
2614 error
= dir
->i_op
->create(dir
, dentry
, mode
, want_excl
);
2616 fsnotify_create(dir
, dentry
);
2619 EXPORT_SYMBOL(vfs_create
);
2621 static int may_open(struct path
*path
, int acc_mode
, int flag
)
2623 struct dentry
*dentry
= path
->dentry
;
2624 struct inode
*inode
= dentry
->d_inode
;
2634 switch (inode
->i_mode
& S_IFMT
) {
2638 if (acc_mode
& MAY_WRITE
)
2643 if (path
->mnt
->mnt_flags
& MNT_NODEV
)
2652 error
= inode_permission(inode
, acc_mode
);
2657 * An append-only file must be opened in append mode for writing.
2659 if (IS_APPEND(inode
)) {
2660 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
2666 /* O_NOATIME can only be set by the owner or superuser */
2667 if (flag
& O_NOATIME
&& !inode_owner_or_capable(inode
))
2673 static int handle_truncate(struct file
*filp
)
2675 struct path
*path
= &filp
->f_path
;
2676 struct inode
*inode
= path
->dentry
->d_inode
;
2677 int error
= get_write_access(inode
);
2681 * Refuse to truncate files with mandatory locks held on them.
2683 error
= locks_verify_locked(filp
);
2685 error
= security_path_truncate(path
);
2687 error
= do_truncate(path
->dentry
, 0,
2688 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
2691 put_write_access(inode
);
2695 static inline int open_to_namei_flags(int flag
)
2697 if ((flag
& O_ACCMODE
) == 3)
2702 static int may_o_create(struct path
*dir
, struct dentry
*dentry
, umode_t mode
)
2704 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
2708 error
= inode_permission(dir
->dentry
->d_inode
, MAY_WRITE
| MAY_EXEC
);
2712 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
2716 * Attempt to atomically look up, create and open a file from a negative
2719 * Returns 0 if successful. The file will have been created and attached to
2720 * @file by the filesystem calling finish_open().
2722 * Returns 1 if the file was looked up only or didn't need creating. The
2723 * caller will need to perform the open themselves. @path will have been
2724 * updated to point to the new dentry. This may be negative.
2726 * Returns an error code otherwise.
2728 static int atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
2729 struct path
*path
, struct file
*file
,
2730 const struct open_flags
*op
,
2731 bool got_write
, bool need_lookup
,
2734 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
2735 unsigned open_flag
= open_to_namei_flags(op
->open_flag
);
2739 int create_error
= 0;
2740 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
2743 BUG_ON(dentry
->d_inode
);
2745 /* Don't create child dentry for a dead directory. */
2746 if (unlikely(IS_DEADDIR(dir
))) {
2752 if ((open_flag
& O_CREAT
) && !IS_POSIXACL(dir
))
2753 mode
&= ~current_umask();
2755 excl
= (open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
);
2757 open_flag
&= ~O_TRUNC
;
2760 * Checking write permission is tricky, bacuse we don't know if we are
2761 * going to actually need it: O_CREAT opens should work as long as the
2762 * file exists. But checking existence breaks atomicity. The trick is
2763 * to check access and if not granted clear O_CREAT from the flags.
2765 * Another problem is returing the "right" error value (e.g. for an
2766 * O_EXCL open we want to return EEXIST not EROFS).
2768 if (((open_flag
& (O_CREAT
| O_TRUNC
)) ||
2769 (open_flag
& O_ACCMODE
) != O_RDONLY
) && unlikely(!got_write
)) {
2770 if (!(open_flag
& O_CREAT
)) {
2772 * No O_CREATE -> atomicity not a requirement -> fall
2773 * back to lookup + open
2776 } else if (open_flag
& (O_EXCL
| O_TRUNC
)) {
2777 /* Fall back and fail with the right error */
2778 create_error
= -EROFS
;
2781 /* No side effects, safe to clear O_CREAT */
2782 create_error
= -EROFS
;
2783 open_flag
&= ~O_CREAT
;
2787 if (open_flag
& O_CREAT
) {
2788 error
= may_o_create(&nd
->path
, dentry
, mode
);
2790 create_error
= error
;
2791 if (open_flag
& O_EXCL
)
2793 open_flag
&= ~O_CREAT
;
2797 if (nd
->flags
& LOOKUP_DIRECTORY
)
2798 open_flag
|= O_DIRECTORY
;
2800 file
->f_path
.dentry
= DENTRY_NOT_SET
;
2801 file
->f_path
.mnt
= nd
->path
.mnt
;
2802 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
, open_flag
, mode
,
2805 if (create_error
&& error
== -ENOENT
)
2806 error
= create_error
;
2810 if (error
) { /* returned 1, that is */
2811 if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
2815 if (file
->f_path
.dentry
) {
2817 dentry
= file
->f_path
.dentry
;
2819 if (*opened
& FILE_CREATED
)
2820 fsnotify_create(dir
, dentry
);
2821 if (!dentry
->d_inode
) {
2822 WARN_ON(*opened
& FILE_CREATED
);
2824 error
= create_error
;
2828 if (excl
&& !(*opened
& FILE_CREATED
)) {
2837 * We didn't have the inode before the open, so check open permission
2840 acc_mode
= op
->acc_mode
;
2841 if (*opened
& FILE_CREATED
) {
2842 WARN_ON(!(open_flag
& O_CREAT
));
2843 fsnotify_create(dir
, dentry
);
2844 acc_mode
= MAY_OPEN
;
2846 error
= may_open(&file
->f_path
, acc_mode
, open_flag
);
2856 dentry
= lookup_real(dir
, dentry
, nd
->flags
);
2858 return PTR_ERR(dentry
);
2861 int open_flag
= op
->open_flag
;
2863 error
= create_error
;
2864 if ((open_flag
& O_EXCL
)) {
2865 if (!dentry
->d_inode
)
2867 } else if (!dentry
->d_inode
) {
2869 } else if ((open_flag
& O_TRUNC
) &&
2873 /* will fail later, go on to get the right error */
2877 path
->dentry
= dentry
;
2878 path
->mnt
= nd
->path
.mnt
;
2883 * Look up and maybe create and open the last component.
2885 * Must be called with i_mutex held on parent.
2887 * Returns 0 if the file was successfully atomically created (if necessary) and
2888 * opened. In this case the file will be returned attached to @file.
2890 * Returns 1 if the file was not completely opened at this time, though lookups
2891 * and creations will have been performed and the dentry returned in @path will
2892 * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
2893 * specified then a negative dentry may be returned.
2895 * An error code is returned otherwise.
2897 * FILE_CREATE will be set in @*opened if the dentry was created and will be
2898 * cleared otherwise prior to returning.
2900 static int lookup_open(struct nameidata
*nd
, struct path
*path
,
2902 const struct open_flags
*op
,
2903 bool got_write
, int *opened
)
2905 struct dentry
*dir
= nd
->path
.dentry
;
2906 struct inode
*dir_inode
= dir
->d_inode
;
2907 struct dentry
*dentry
;
2911 *opened
&= ~FILE_CREATED
;
2912 dentry
= lookup_dcache(&nd
->last
, dir
, nd
->flags
, &need_lookup
);
2914 return PTR_ERR(dentry
);
2916 /* Cached positive dentry: will open in f_op->open */
2917 if (!need_lookup
&& dentry
->d_inode
)
2920 if ((nd
->flags
& LOOKUP_OPEN
) && dir_inode
->i_op
->atomic_open
) {
2921 return atomic_open(nd
, dentry
, path
, file
, op
, got_write
,
2922 need_lookup
, opened
);
2926 BUG_ON(dentry
->d_inode
);
2928 dentry
= lookup_real(dir_inode
, dentry
, nd
->flags
);
2930 return PTR_ERR(dentry
);
2933 /* Negative dentry, just create the file */
2934 if (!dentry
->d_inode
&& (op
->open_flag
& O_CREAT
)) {
2935 umode_t mode
= op
->mode
;
2936 if (!IS_POSIXACL(dir
->d_inode
))
2937 mode
&= ~current_umask();
2939 * This write is needed to ensure that a
2940 * rw->ro transition does not occur between
2941 * the time when the file is created and when
2942 * a permanent write count is taken through
2943 * the 'struct file' in finish_open().
2949 *opened
|= FILE_CREATED
;
2950 error
= security_path_mknod(&nd
->path
, dentry
, mode
, 0);
2953 error
= vfs_create(dir
->d_inode
, dentry
, mode
,
2954 nd
->flags
& LOOKUP_EXCL
);
2959 path
->dentry
= dentry
;
2960 path
->mnt
= nd
->path
.mnt
;
2969 * Handle the last step of open()
2971 static int do_last(struct nameidata
*nd
,
2972 struct file
*file
, const struct open_flags
*op
,
2973 int *opened
, struct filename
*name
)
2975 struct dentry
*dir
= nd
->path
.dentry
;
2976 int open_flag
= op
->open_flag
;
2977 bool will_truncate
= (open_flag
& O_TRUNC
) != 0;
2978 bool got_write
= false;
2979 int acc_mode
= op
->acc_mode
;
2980 struct inode
*inode
;
2981 struct path save_parent
= { .dentry
= NULL
, .mnt
= NULL
};
2983 bool retried
= false;
2986 nd
->flags
&= ~LOOKUP_PARENT
;
2987 nd
->flags
|= op
->intent
;
2989 if (nd
->last_type
!= LAST_NORM
) {
2990 error
= handle_dots(nd
, nd
->last_type
);
2996 if (!(open_flag
& O_CREAT
)) {
2997 if (nd
->last
.name
[nd
->last
.len
])
2998 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2999 /* we _can_ be in RCU mode here */
3000 error
= lookup_fast(nd
, &path
, &inode
);
3007 BUG_ON(nd
->inode
!= dir
->d_inode
);
3009 /* create side of things */
3011 * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
3012 * has been cleared when we got to the last component we are
3015 error
= complete_walk(nd
);
3019 audit_inode(name
, dir
, LOOKUP_PARENT
);
3021 /* trailing slashes? */
3022 if (nd
->last
.name
[nd
->last
.len
])
3027 if (op
->open_flag
& (O_CREAT
| O_TRUNC
| O_WRONLY
| O_RDWR
)) {
3028 error
= mnt_want_write(nd
->path
.mnt
);
3032 * do _not_ fail yet - we might not need that or fail with
3033 * a different error; let lookup_open() decide; we'll be
3034 * dropping this one anyway.
3037 mutex_lock(&dir
->d_inode
->i_mutex
);
3038 error
= lookup_open(nd
, &path
, file
, op
, got_write
, opened
);
3039 mutex_unlock(&dir
->d_inode
->i_mutex
);
3045 if ((*opened
& FILE_CREATED
) ||
3046 !S_ISREG(file_inode(file
)->i_mode
))
3047 will_truncate
= false;
3049 audit_inode(name
, file
->f_path
.dentry
, 0);
3053 if (*opened
& FILE_CREATED
) {
3054 /* Don't check for write permission, don't truncate */
3055 open_flag
&= ~O_TRUNC
;
3056 will_truncate
= false;
3057 acc_mode
= MAY_OPEN
;
3058 path_to_nameidata(&path
, nd
);
3059 goto finish_open_created
;
3063 * create/update audit record if it already exists.
3065 if (d_is_positive(path
.dentry
))
3066 audit_inode(name
, path
.dentry
, 0);
3069 * If atomic_open() acquired write access it is dropped now due to
3070 * possible mount and symlink following (this might be optimized away if
3074 mnt_drop_write(nd
->path
.mnt
);
3079 if ((open_flag
& (O_EXCL
| O_CREAT
)) == (O_EXCL
| O_CREAT
))
3082 error
= follow_managed(&path
, nd
->flags
);
3087 nd
->flags
|= LOOKUP_JUMPED
;
3089 BUG_ON(nd
->flags
& LOOKUP_RCU
);
3090 inode
= path
.dentry
->d_inode
;
3092 if (d_is_negative(path
.dentry
)) {
3093 path_to_nameidata(&path
, nd
);
3097 if (should_follow_link(path
.dentry
, nd
->flags
& LOOKUP_FOLLOW
)) {
3098 if (nd
->flags
& LOOKUP_RCU
) {
3099 if (unlikely(nd
->path
.mnt
!= path
.mnt
||
3100 unlazy_walk(nd
, path
.dentry
))) {
3105 BUG_ON(inode
!= path
.dentry
->d_inode
);
3110 if (unlikely(d_is_symlink(path
.dentry
)) && !(open_flag
& O_PATH
)) {
3111 path_to_nameidata(&path
, nd
);
3116 if ((nd
->flags
& LOOKUP_RCU
) || nd
->path
.mnt
!= path
.mnt
) {
3117 path_to_nameidata(&path
, nd
);
3119 save_parent
.dentry
= nd
->path
.dentry
;
3120 save_parent
.mnt
= mntget(path
.mnt
);
3121 nd
->path
.dentry
= path
.dentry
;
3125 /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
3127 error
= complete_walk(nd
);
3129 path_put(&save_parent
);
3132 audit_inode(name
, nd
->path
.dentry
, 0);
3134 if ((open_flag
& O_CREAT
) && d_is_dir(nd
->path
.dentry
))
3137 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !d_can_lookup(nd
->path
.dentry
))
3139 if (!d_is_reg(nd
->path
.dentry
))
3140 will_truncate
= false;
3142 if (will_truncate
) {
3143 error
= mnt_want_write(nd
->path
.mnt
);
3148 finish_open_created
:
3149 error
= may_open(&nd
->path
, acc_mode
, open_flag
);
3153 BUG_ON(*opened
& FILE_OPENED
); /* once it's opened, it's opened */
3154 error
= vfs_open(&nd
->path
, file
, current_cred());
3156 *opened
|= FILE_OPENED
;
3158 if (error
== -EOPENSTALE
)
3163 error
= open_check_o_direct(file
);
3166 error
= ima_file_check(file
, op
->acc_mode
, *opened
);
3170 if (will_truncate
) {
3171 error
= handle_truncate(file
);
3177 mnt_drop_write(nd
->path
.mnt
);
3178 path_put(&save_parent
);
3183 path_put_conditional(&path
, nd
);
3190 /* If no saved parent or already retried then can't retry */
3191 if (!save_parent
.dentry
|| retried
)
3194 BUG_ON(save_parent
.dentry
!= dir
);
3195 path_put(&nd
->path
);
3196 nd
->path
= save_parent
;
3197 nd
->inode
= dir
->d_inode
;
3198 save_parent
.mnt
= NULL
;
3199 save_parent
.dentry
= NULL
;
3201 mnt_drop_write(nd
->path
.mnt
);
3208 static int do_tmpfile(int dfd
, struct filename
*pathname
,
3209 struct nameidata
*nd
, int flags
,
3210 const struct open_flags
*op
,
3211 struct file
*file
, int *opened
)
3213 static const struct qstr name
= QSTR_INIT("/", 1);
3214 struct dentry
*dentry
, *child
;
3216 int error
= path_lookupat(dfd
, pathname
,
3217 flags
| LOOKUP_DIRECTORY
, nd
);
3218 if (unlikely(error
))
3220 error
= mnt_want_write(nd
->path
.mnt
);
3221 if (unlikely(error
))
3223 /* we want directory to be writable */
3224 error
= inode_permission(nd
->inode
, MAY_WRITE
| MAY_EXEC
);
3227 dentry
= nd
->path
.dentry
;
3228 dir
= dentry
->d_inode
;
3229 if (!dir
->i_op
->tmpfile
) {
3230 error
= -EOPNOTSUPP
;
3233 child
= d_alloc(dentry
, &name
);
3234 if (unlikely(!child
)) {
3238 nd
->flags
&= ~LOOKUP_DIRECTORY
;
3239 nd
->flags
|= op
->intent
;
3240 dput(nd
->path
.dentry
);
3241 nd
->path
.dentry
= child
;
3242 error
= dir
->i_op
->tmpfile(dir
, nd
->path
.dentry
, op
->mode
);
3245 audit_inode(pathname
, nd
->path
.dentry
, 0);
3246 /* Don't check for other permissions, the inode was just created */
3247 error
= may_open(&nd
->path
, MAY_OPEN
, op
->open_flag
);
3250 file
->f_path
.mnt
= nd
->path
.mnt
;
3251 error
= finish_open(file
, nd
->path
.dentry
, NULL
, opened
);
3254 error
= open_check_o_direct(file
);
3257 } else if (!(op
->open_flag
& O_EXCL
)) {
3258 struct inode
*inode
= file_inode(file
);
3259 spin_lock(&inode
->i_lock
);
3260 inode
->i_state
|= I_LINKABLE
;
3261 spin_unlock(&inode
->i_lock
);
3264 mnt_drop_write(nd
->path
.mnt
);
3266 path_put(&nd
->path
);
3270 static struct file
*path_openat(int dfd
, struct filename
*pathname
,
3271 struct nameidata
*nd
, const struct open_flags
*op
, int flags
)
3277 file
= get_empty_filp();
3281 file
->f_flags
= op
->open_flag
;
3283 if (unlikely(file
->f_flags
& __O_TMPFILE
)) {
3284 error
= do_tmpfile(dfd
, pathname
, nd
, flags
, op
, file
, &opened
);
3288 error
= path_init(dfd
, pathname
, flags
, nd
);
3289 if (unlikely(error
))
3292 error
= do_last(nd
, file
, op
, &opened
, pathname
);
3293 while (unlikely(error
> 0)) { /* trailing symlink */
3294 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
3295 error
= trailing_symlink(nd
);
3296 if (unlikely(error
))
3298 error
= do_last(nd
, file
, op
, &opened
, pathname
);
3304 if (!(opened
& FILE_OPENED
)) {
3308 if (unlikely(error
)) {
3309 if (error
== -EOPENSTALE
) {
3310 if (flags
& LOOKUP_RCU
)
3315 file
= ERR_PTR(error
);
3320 struct file
*do_filp_open(int dfd
, struct filename
*pathname
,
3321 const struct open_flags
*op
)
3323 struct nameidata nd
;
3324 int flags
= op
->lookup_flags
;
3328 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
| LOOKUP_RCU
);
3329 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
3330 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
);
3331 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
3332 filp
= path_openat(dfd
, pathname
, &nd
, op
, flags
| LOOKUP_REVAL
);
3333 restore_nameidata(&nd
);
3337 struct file
*do_file_open_root(struct dentry
*dentry
, struct vfsmount
*mnt
,
3338 const char *name
, const struct open_flags
*op
)
3340 struct nameidata nd
;
3342 struct filename
*filename
;
3343 int flags
= op
->lookup_flags
| LOOKUP_ROOT
;
3346 nd
.root
.dentry
= dentry
;
3349 if (d_is_symlink(dentry
) && op
->intent
& LOOKUP_OPEN
)
3350 return ERR_PTR(-ELOOP
);
3352 filename
= getname_kernel(name
);
3353 if (unlikely(IS_ERR(filename
)))
3354 return ERR_CAST(filename
);
3356 file
= path_openat(-1, filename
, &nd
, op
, flags
| LOOKUP_RCU
);
3357 if (unlikely(file
== ERR_PTR(-ECHILD
)))
3358 file
= path_openat(-1, filename
, &nd
, op
, flags
);
3359 if (unlikely(file
== ERR_PTR(-ESTALE
)))
3360 file
= path_openat(-1, filename
, &nd
, op
, flags
| LOOKUP_REVAL
);
3361 restore_nameidata(&nd
);
3366 static struct dentry
*filename_create(int dfd
, struct filename
*name
,
3367 struct path
*path
, unsigned int lookup_flags
)
3369 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
3370 struct nameidata nd
;
3373 bool is_dir
= (lookup_flags
& LOOKUP_DIRECTORY
);
3376 * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
3377 * other flags passed in are ignored!
3379 lookup_flags
&= LOOKUP_REVAL
;
3381 error
= filename_lookup(dfd
, name
, LOOKUP_PARENT
|lookup_flags
, &nd
);
3383 return ERR_PTR(error
);
3386 * Yucky last component or no last component at all?
3387 * (foo/., foo/.., /////)
3389 if (nd
.last_type
!= LAST_NORM
)
3391 nd
.flags
&= ~LOOKUP_PARENT
;
3392 nd
.flags
|= LOOKUP_CREATE
| LOOKUP_EXCL
;
3394 /* don't fail immediately if it's r/o, at least try to report other errors */
3395 err2
= mnt_want_write(nd
.path
.mnt
);
3397 * Do the final lookup.
3399 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3400 dentry
= __lookup_hash(&nd
.last
, nd
.path
.dentry
, nd
.flags
);
3405 if (d_is_positive(dentry
))
3409 * Special case - lookup gave negative, but... we had foo/bar/
3410 * From the vfs_mknod() POV we just have a negative dentry -
3411 * all is fine. Let's be bastards - you had / on the end, you've
3412 * been asking for (non-existent) directory. -ENOENT for you.
3414 if (unlikely(!is_dir
&& nd
.last
.name
[nd
.last
.len
])) {
3418 if (unlikely(err2
)) {
3426 dentry
= ERR_PTR(error
);
3428 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
3430 mnt_drop_write(nd
.path
.mnt
);
3436 struct dentry
*kern_path_create(int dfd
, const char *pathname
,
3437 struct path
*path
, unsigned int lookup_flags
)
3439 struct filename
*filename
= getname_kernel(pathname
);
3442 if (IS_ERR(filename
))
3443 return ERR_CAST(filename
);
3444 res
= filename_create(dfd
, filename
, path
, lookup_flags
);
3448 EXPORT_SYMBOL(kern_path_create
);
3450 void done_path_create(struct path
*path
, struct dentry
*dentry
)
3453 mutex_unlock(&path
->dentry
->d_inode
->i_mutex
);
3454 mnt_drop_write(path
->mnt
);
3457 EXPORT_SYMBOL(done_path_create
);
3459 struct dentry
*user_path_create(int dfd
, const char __user
*pathname
,
3460 struct path
*path
, unsigned int lookup_flags
)
3462 struct filename
*tmp
= getname(pathname
);
3465 return ERR_CAST(tmp
);
3466 res
= filename_create(dfd
, tmp
, path
, lookup_flags
);
3470 EXPORT_SYMBOL(user_path_create
);
3472 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3474 int error
= may_create(dir
, dentry
);
3479 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
3482 if (!dir
->i_op
->mknod
)
3485 error
= devcgroup_inode_mknod(mode
, dev
);
3489 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
3493 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
3495 fsnotify_create(dir
, dentry
);
3498 EXPORT_SYMBOL(vfs_mknod
);
3500 static int may_mknod(umode_t mode
)
3502 switch (mode
& S_IFMT
) {
3508 case 0: /* zero mode translates to S_IFREG */
3517 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
3520 struct dentry
*dentry
;
3523 unsigned int lookup_flags
= 0;
3525 error
= may_mknod(mode
);
3529 dentry
= user_path_create(dfd
, filename
, &path
, lookup_flags
);
3531 return PTR_ERR(dentry
);
3533 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3534 mode
&= ~current_umask();
3535 error
= security_path_mknod(&path
, dentry
, mode
, dev
);
3538 switch (mode
& S_IFMT
) {
3539 case 0: case S_IFREG
:
3540 error
= vfs_create(path
.dentry
->d_inode
,dentry
,mode
,true);
3542 case S_IFCHR
: case S_IFBLK
:
3543 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,
3544 new_decode_dev(dev
));
3546 case S_IFIFO
: case S_IFSOCK
:
3547 error
= vfs_mknod(path
.dentry
->d_inode
,dentry
,mode
,0);
3551 done_path_create(&path
, dentry
);
3552 if (retry_estale(error
, lookup_flags
)) {
3553 lookup_flags
|= LOOKUP_REVAL
;
3559 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
3561 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
3564 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
3566 int error
= may_create(dir
, dentry
);
3567 unsigned max_links
= dir
->i_sb
->s_max_links
;
3572 if (!dir
->i_op
->mkdir
)
3575 mode
&= (S_IRWXUGO
|S_ISVTX
);
3576 error
= security_inode_mkdir(dir
, dentry
, mode
);
3580 if (max_links
&& dir
->i_nlink
>= max_links
)
3583 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
3585 fsnotify_mkdir(dir
, dentry
);
3588 EXPORT_SYMBOL(vfs_mkdir
);
3590 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, umode_t
, mode
)
3592 struct dentry
*dentry
;
3595 unsigned int lookup_flags
= LOOKUP_DIRECTORY
;
3598 dentry
= user_path_create(dfd
, pathname
, &path
, lookup_flags
);
3600 return PTR_ERR(dentry
);
3602 if (!IS_POSIXACL(path
.dentry
->d_inode
))
3603 mode
&= ~current_umask();
3604 error
= security_path_mkdir(&path
, dentry
, mode
);
3606 error
= vfs_mkdir(path
.dentry
->d_inode
, dentry
, mode
);
3607 done_path_create(&path
, dentry
);
3608 if (retry_estale(error
, lookup_flags
)) {
3609 lookup_flags
|= LOOKUP_REVAL
;
3615 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, umode_t
, mode
)
3617 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
3621 * The dentry_unhash() helper will try to drop the dentry early: we
3622 * should have a usage count of 1 if we're the only user of this
3623 * dentry, and if that is true (possibly after pruning the dcache),
3624 * then we drop the dentry now.
3626 * A low-level filesystem can, if it choses, legally
3629 * if (!d_unhashed(dentry))
3632 * if it cannot handle the case of removing a directory
3633 * that is still in use by something else..
3635 void dentry_unhash(struct dentry
*dentry
)
3637 shrink_dcache_parent(dentry
);
3638 spin_lock(&dentry
->d_lock
);
3639 if (dentry
->d_lockref
.count
== 1)
3641 spin_unlock(&dentry
->d_lock
);
3643 EXPORT_SYMBOL(dentry_unhash
);
3645 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
3647 int error
= may_delete(dir
, dentry
, 1);
3652 if (!dir
->i_op
->rmdir
)
3656 mutex_lock(&dentry
->d_inode
->i_mutex
);
3659 if (is_local_mountpoint(dentry
))
3662 error
= security_inode_rmdir(dir
, dentry
);
3666 shrink_dcache_parent(dentry
);
3667 error
= dir
->i_op
->rmdir(dir
, dentry
);
3671 dentry
->d_inode
->i_flags
|= S_DEAD
;
3673 detach_mounts(dentry
);
3676 mutex_unlock(&dentry
->d_inode
->i_mutex
);
3682 EXPORT_SYMBOL(vfs_rmdir
);
3684 static long do_rmdir(int dfd
, const char __user
*pathname
)
3687 struct filename
*name
;
3688 struct dentry
*dentry
;
3692 unsigned int lookup_flags
= 0;
3694 name
= user_path_parent(dfd
, pathname
,
3695 &path
, &last
, &type
, lookup_flags
);
3697 return PTR_ERR(name
);
3711 error
= mnt_want_write(path
.mnt
);
3715 mutex_lock_nested(&path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3716 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3717 error
= PTR_ERR(dentry
);
3720 if (!dentry
->d_inode
) {
3724 error
= security_path_rmdir(&path
, dentry
);
3727 error
= vfs_rmdir(path
.dentry
->d_inode
, dentry
);
3731 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3732 mnt_drop_write(path
.mnt
);
3736 if (retry_estale(error
, lookup_flags
)) {
3737 lookup_flags
|= LOOKUP_REVAL
;
3743 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
3745 return do_rmdir(AT_FDCWD
, pathname
);
3749 * vfs_unlink - unlink a filesystem object
3750 * @dir: parent directory
3752 * @delegated_inode: returns victim inode, if the inode is delegated.
3754 * The caller must hold dir->i_mutex.
3756 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
3757 * return a reference to the inode in delegated_inode. The caller
3758 * should then break the delegation on that inode and retry. Because
3759 * breaking a delegation may take a long time, the caller should drop
3760 * dir->i_mutex before doing so.
3762 * Alternatively, a caller may pass NULL for delegated_inode. This may
3763 * be appropriate for callers that expect the underlying filesystem not
3764 * to be NFS exported.
3766 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
, struct inode
**delegated_inode
)
3768 struct inode
*target
= dentry
->d_inode
;
3769 int error
= may_delete(dir
, dentry
, 0);
3774 if (!dir
->i_op
->unlink
)
3777 mutex_lock(&target
->i_mutex
);
3778 if (is_local_mountpoint(dentry
))
3781 error
= security_inode_unlink(dir
, dentry
);
3783 error
= try_break_deleg(target
, delegated_inode
);
3786 error
= dir
->i_op
->unlink(dir
, dentry
);
3789 detach_mounts(dentry
);
3794 mutex_unlock(&target
->i_mutex
);
3796 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
3797 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
3798 fsnotify_link_count(target
);
3804 EXPORT_SYMBOL(vfs_unlink
);
3807 * Make sure that the actual truncation of the file will occur outside its
3808 * directory's i_mutex. Truncate can take a long time if there is a lot of
3809 * writeout happening, and we don't want to prevent access to the directory
3810 * while waiting on the I/O.
3812 static long do_unlinkat(int dfd
, const char __user
*pathname
)
3815 struct filename
*name
;
3816 struct dentry
*dentry
;
3820 struct inode
*inode
= NULL
;
3821 struct inode
*delegated_inode
= NULL
;
3822 unsigned int lookup_flags
= 0;
3824 name
= user_path_parent(dfd
, pathname
,
3825 &path
, &last
, &type
, lookup_flags
);
3827 return PTR_ERR(name
);
3830 if (type
!= LAST_NORM
)
3833 error
= mnt_want_write(path
.mnt
);
3837 mutex_lock_nested(&path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
3838 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
3839 error
= PTR_ERR(dentry
);
3840 if (!IS_ERR(dentry
)) {
3841 /* Why not before? Because we want correct error value */
3842 if (last
.name
[last
.len
])
3844 inode
= dentry
->d_inode
;
3845 if (d_is_negative(dentry
))
3848 error
= security_path_unlink(&path
, dentry
);
3851 error
= vfs_unlink(path
.dentry
->d_inode
, dentry
, &delegated_inode
);
3855 mutex_unlock(&path
.dentry
->d_inode
->i_mutex
);
3857 iput(inode
); /* truncate the inode here */
3859 if (delegated_inode
) {
3860 error
= break_deleg_wait(&delegated_inode
);
3864 mnt_drop_write(path
.mnt
);
3868 if (retry_estale(error
, lookup_flags
)) {
3869 lookup_flags
|= LOOKUP_REVAL
;
3876 if (d_is_negative(dentry
))
3878 else if (d_is_dir(dentry
))
3885 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
3887 if ((flag
& ~AT_REMOVEDIR
) != 0)
3890 if (flag
& AT_REMOVEDIR
)
3891 return do_rmdir(dfd
, pathname
);
3893 return do_unlinkat(dfd
, pathname
);
3896 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
3898 return do_unlinkat(AT_FDCWD
, pathname
);
3901 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
3903 int error
= may_create(dir
, dentry
);
3908 if (!dir
->i_op
->symlink
)
3911 error
= security_inode_symlink(dir
, dentry
, oldname
);
3915 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
3917 fsnotify_create(dir
, dentry
);
3920 EXPORT_SYMBOL(vfs_symlink
);
3922 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
3923 int, newdfd
, const char __user
*, newname
)
3926 struct filename
*from
;
3927 struct dentry
*dentry
;
3929 unsigned int lookup_flags
= 0;
3931 from
= getname(oldname
);
3933 return PTR_ERR(from
);
3935 dentry
= user_path_create(newdfd
, newname
, &path
, lookup_flags
);
3936 error
= PTR_ERR(dentry
);
3940 error
= security_path_symlink(&path
, dentry
, from
->name
);
3942 error
= vfs_symlink(path
.dentry
->d_inode
, dentry
, from
->name
);
3943 done_path_create(&path
, dentry
);
3944 if (retry_estale(error
, lookup_flags
)) {
3945 lookup_flags
|= LOOKUP_REVAL
;
3953 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
3955 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
3959 * vfs_link - create a new link
3960 * @old_dentry: object to be linked
3962 * @new_dentry: where to create the new link
3963 * @delegated_inode: returns inode needing a delegation break
3965 * The caller must hold dir->i_mutex
3967 * If vfs_link discovers a delegation on the to-be-linked file in need
3968 * of breaking, it will return -EWOULDBLOCK and return a reference to the
3969 * inode in delegated_inode. The caller should then break the delegation
3970 * and retry. Because breaking a delegation may take a long time, the
3971 * caller should drop the i_mutex before doing so.
3973 * Alternatively, a caller may pass NULL for delegated_inode. This may
3974 * be appropriate for callers that expect the underlying filesystem not
3975 * to be NFS exported.
3977 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
, struct inode
**delegated_inode
)
3979 struct inode
*inode
= old_dentry
->d_inode
;
3980 unsigned max_links
= dir
->i_sb
->s_max_links
;
3986 error
= may_create(dir
, new_dentry
);
3990 if (dir
->i_sb
!= inode
->i_sb
)
3994 * A link to an append-only or immutable file cannot be created.
3996 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
3998 if (!dir
->i_op
->link
)
4000 if (S_ISDIR(inode
->i_mode
))
4003 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
4007 mutex_lock(&inode
->i_mutex
);
4008 /* Make sure we don't allow creating hardlink to an unlinked file */
4009 if (inode
->i_nlink
== 0 && !(inode
->i_state
& I_LINKABLE
))
4011 else if (max_links
&& inode
->i_nlink
>= max_links
)
4014 error
= try_break_deleg(inode
, delegated_inode
);
4016 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
4019 if (!error
&& (inode
->i_state
& I_LINKABLE
)) {
4020 spin_lock(&inode
->i_lock
);
4021 inode
->i_state
&= ~I_LINKABLE
;
4022 spin_unlock(&inode
->i_lock
);
4024 mutex_unlock(&inode
->i_mutex
);
4026 fsnotify_link(dir
, inode
, new_dentry
);
4029 EXPORT_SYMBOL(vfs_link
);
4032 * Hardlinks are often used in delicate situations. We avoid
4033 * security-related surprises by not following symlinks on the
4036 * We don't follow them on the oldname either to be compatible
4037 * with linux 2.0, and to avoid hard-linking to directories
4038 * and other special files. --ADM
4040 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
4041 int, newdfd
, const char __user
*, newname
, int, flags
)
4043 struct dentry
*new_dentry
;
4044 struct path old_path
, new_path
;
4045 struct inode
*delegated_inode
= NULL
;
4049 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0)
4052 * To use null names we require CAP_DAC_READ_SEARCH
4053 * This ensures that not everyone will be able to create
4054 * handlink using the passed filedescriptor.
4056 if (flags
& AT_EMPTY_PATH
) {
4057 if (!capable(CAP_DAC_READ_SEARCH
))
4062 if (flags
& AT_SYMLINK_FOLLOW
)
4063 how
|= LOOKUP_FOLLOW
;
4065 error
= user_path_at(olddfd
, oldname
, how
, &old_path
);
4069 new_dentry
= user_path_create(newdfd
, newname
, &new_path
,
4070 (how
& LOOKUP_REVAL
));
4071 error
= PTR_ERR(new_dentry
);
4072 if (IS_ERR(new_dentry
))
4076 if (old_path
.mnt
!= new_path
.mnt
)
4078 error
= may_linkat(&old_path
);
4079 if (unlikely(error
))
4081 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
4084 error
= vfs_link(old_path
.dentry
, new_path
.dentry
->d_inode
, new_dentry
, &delegated_inode
);
4086 done_path_create(&new_path
, new_dentry
);
4087 if (delegated_inode
) {
4088 error
= break_deleg_wait(&delegated_inode
);
4090 path_put(&old_path
);
4094 if (retry_estale(error
, how
)) {
4095 path_put(&old_path
);
4096 how
|= LOOKUP_REVAL
;
4100 path_put(&old_path
);
4105 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
4107 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4111 * vfs_rename - rename a filesystem object
4112 * @old_dir: parent of source
4113 * @old_dentry: source
4114 * @new_dir: parent of destination
4115 * @new_dentry: destination
4116 * @delegated_inode: returns an inode needing a delegation break
4117 * @flags: rename flags
4119 * The caller must hold multiple mutexes--see lock_rename()).
4121 * If vfs_rename discovers a delegation in need of breaking at either
4122 * the source or destination, it will return -EWOULDBLOCK and return a
4123 * reference to the inode in delegated_inode. The caller should then
4124 * break the delegation and retry. Because breaking a delegation may
4125 * take a long time, the caller should drop all locks before doing
4128 * Alternatively, a caller may pass NULL for delegated_inode. This may
4129 * be appropriate for callers that expect the underlying filesystem not
4130 * to be NFS exported.
4132 * The worst of all namespace operations - renaming directory. "Perverted"
4133 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4135 * a) we can get into loop creation.
4136 * b) race potential - two innocent renames can create a loop together.
4137 * That's where 4.4 screws up. Current fix: serialization on
4138 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
4140 * c) we have to lock _four_ objects - parents and victim (if it exists),
4141 * and source (if it is not a directory).
4142 * And that - after we got ->i_mutex on parents (until then we don't know
4143 * whether the target exists). Solution: try to be smart with locking
4144 * order for inodes. We rely on the fact that tree topology may change
4145 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
4146 * move will be locked. Thus we can rank directories by the tree
4147 * (ancestors first) and rank all non-directories after them.
4148 * That works since everybody except rename does "lock parent, lookup,
4149 * lock child" and rename is under ->s_vfs_rename_mutex.
4150 * HOWEVER, it relies on the assumption that any object with ->lookup()
4151 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4152 * we'd better make sure that there's no link(2) for them.
4153 * d) conversion from fhandle to dentry may come in the wrong moment - when
4154 * we are removing the target. Solution: we will have to grab ->i_mutex
4155 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
4156 * ->i_mutex on parents, which works but leads to some truly excessive
4159 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
4160 struct inode
*new_dir
, struct dentry
*new_dentry
,
4161 struct inode
**delegated_inode
, unsigned int flags
)
4164 bool is_dir
= d_is_dir(old_dentry
);
4165 const unsigned char *old_name
;
4166 struct inode
*source
= old_dentry
->d_inode
;
4167 struct inode
*target
= new_dentry
->d_inode
;
4168 bool new_is_dir
= false;
4169 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
4171 if (source
== target
)
4174 error
= may_delete(old_dir
, old_dentry
, is_dir
);
4179 error
= may_create(new_dir
, new_dentry
);
4181 new_is_dir
= d_is_dir(new_dentry
);
4183 if (!(flags
& RENAME_EXCHANGE
))
4184 error
= may_delete(new_dir
, new_dentry
, is_dir
);
4186 error
= may_delete(new_dir
, new_dentry
, new_is_dir
);
4191 if (!old_dir
->i_op
->rename
&& !old_dir
->i_op
->rename2
)
4194 if (flags
&& !old_dir
->i_op
->rename2
)
4198 * If we are going to change the parent - check write permissions,
4199 * we'll need to flip '..'.
4201 if (new_dir
!= old_dir
) {
4203 error
= inode_permission(source
, MAY_WRITE
);
4207 if ((flags
& RENAME_EXCHANGE
) && new_is_dir
) {
4208 error
= inode_permission(target
, MAY_WRITE
);
4214 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
,
4219 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
4221 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4222 lock_two_nondirectories(source
, target
);
4224 mutex_lock(&target
->i_mutex
);
4227 if (is_local_mountpoint(old_dentry
) || is_local_mountpoint(new_dentry
))
4230 if (max_links
&& new_dir
!= old_dir
) {
4232 if (is_dir
&& !new_is_dir
&& new_dir
->i_nlink
>= max_links
)
4234 if ((flags
& RENAME_EXCHANGE
) && !is_dir
&& new_is_dir
&&
4235 old_dir
->i_nlink
>= max_links
)
4238 if (is_dir
&& !(flags
& RENAME_EXCHANGE
) && target
)
4239 shrink_dcache_parent(new_dentry
);
4241 error
= try_break_deleg(source
, delegated_inode
);
4245 if (target
&& !new_is_dir
) {
4246 error
= try_break_deleg(target
, delegated_inode
);
4250 if (!old_dir
->i_op
->rename2
) {
4251 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
,
4252 new_dir
, new_dentry
);
4254 WARN_ON(old_dir
->i_op
->rename
!= NULL
);
4255 error
= old_dir
->i_op
->rename2(old_dir
, old_dentry
,
4256 new_dir
, new_dentry
, flags
);
4261 if (!(flags
& RENAME_EXCHANGE
) && target
) {
4263 target
->i_flags
|= S_DEAD
;
4264 dont_mount(new_dentry
);
4265 detach_mounts(new_dentry
);
4267 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
)) {
4268 if (!(flags
& RENAME_EXCHANGE
))
4269 d_move(old_dentry
, new_dentry
);
4271 d_exchange(old_dentry
, new_dentry
);
4274 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4275 unlock_two_nondirectories(source
, target
);
4277 mutex_unlock(&target
->i_mutex
);
4280 fsnotify_move(old_dir
, new_dir
, old_name
, is_dir
,
4281 !(flags
& RENAME_EXCHANGE
) ? target
: NULL
, old_dentry
);
4282 if (flags
& RENAME_EXCHANGE
) {
4283 fsnotify_move(new_dir
, old_dir
, old_dentry
->d_name
.name
,
4284 new_is_dir
, NULL
, new_dentry
);
4287 fsnotify_oldname_free(old_name
);
4291 EXPORT_SYMBOL(vfs_rename
);
4293 SYSCALL_DEFINE5(renameat2
, int, olddfd
, const char __user
*, oldname
,
4294 int, newdfd
, const char __user
*, newname
, unsigned int, flags
)
4296 struct dentry
*old_dentry
, *new_dentry
;
4297 struct dentry
*trap
;
4298 struct path old_path
, new_path
;
4299 struct qstr old_last
, new_last
;
4300 int old_type
, new_type
;
4301 struct inode
*delegated_inode
= NULL
;
4302 struct filename
*from
;
4303 struct filename
*to
;
4304 unsigned int lookup_flags
= 0, target_flags
= LOOKUP_RENAME_TARGET
;
4305 bool should_retry
= false;
4308 if (flags
& ~(RENAME_NOREPLACE
| RENAME_EXCHANGE
| RENAME_WHITEOUT
))
4311 if ((flags
& (RENAME_NOREPLACE
| RENAME_WHITEOUT
)) &&
4312 (flags
& RENAME_EXCHANGE
))
4315 if ((flags
& RENAME_WHITEOUT
) && !capable(CAP_MKNOD
))
4318 if (flags
& RENAME_EXCHANGE
)
4322 from
= user_path_parent(olddfd
, oldname
,
4323 &old_path
, &old_last
, &old_type
, lookup_flags
);
4325 error
= PTR_ERR(from
);
4329 to
= user_path_parent(newdfd
, newname
,
4330 &new_path
, &new_last
, &new_type
, lookup_flags
);
4332 error
= PTR_ERR(to
);
4337 if (old_path
.mnt
!= new_path
.mnt
)
4341 if (old_type
!= LAST_NORM
)
4344 if (flags
& RENAME_NOREPLACE
)
4346 if (new_type
!= LAST_NORM
)
4349 error
= mnt_want_write(old_path
.mnt
);
4354 trap
= lock_rename(new_path
.dentry
, old_path
.dentry
);
4356 old_dentry
= __lookup_hash(&old_last
, old_path
.dentry
, lookup_flags
);
4357 error
= PTR_ERR(old_dentry
);
4358 if (IS_ERR(old_dentry
))
4360 /* source must exist */
4362 if (d_is_negative(old_dentry
))
4364 new_dentry
= __lookup_hash(&new_last
, new_path
.dentry
, lookup_flags
| target_flags
);
4365 error
= PTR_ERR(new_dentry
);
4366 if (IS_ERR(new_dentry
))
4369 if ((flags
& RENAME_NOREPLACE
) && d_is_positive(new_dentry
))
4371 if (flags
& RENAME_EXCHANGE
) {
4373 if (d_is_negative(new_dentry
))
4376 if (!d_is_dir(new_dentry
)) {
4378 if (new_last
.name
[new_last
.len
])
4382 /* unless the source is a directory trailing slashes give -ENOTDIR */
4383 if (!d_is_dir(old_dentry
)) {
4385 if (old_last
.name
[old_last
.len
])
4387 if (!(flags
& RENAME_EXCHANGE
) && new_last
.name
[new_last
.len
])
4390 /* source should not be ancestor of target */
4392 if (old_dentry
== trap
)
4394 /* target should not be an ancestor of source */
4395 if (!(flags
& RENAME_EXCHANGE
))
4397 if (new_dentry
== trap
)
4400 error
= security_path_rename(&old_path
, old_dentry
,
4401 &new_path
, new_dentry
, flags
);
4404 error
= vfs_rename(old_path
.dentry
->d_inode
, old_dentry
,
4405 new_path
.dentry
->d_inode
, new_dentry
,
4406 &delegated_inode
, flags
);
4412 unlock_rename(new_path
.dentry
, old_path
.dentry
);
4413 if (delegated_inode
) {
4414 error
= break_deleg_wait(&delegated_inode
);
4418 mnt_drop_write(old_path
.mnt
);
4420 if (retry_estale(error
, lookup_flags
))
4421 should_retry
= true;
4422 path_put(&new_path
);
4425 path_put(&old_path
);
4428 should_retry
= false;
4429 lookup_flags
|= LOOKUP_REVAL
;
4436 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
4437 int, newdfd
, const char __user
*, newname
)
4439 return sys_renameat2(olddfd
, oldname
, newdfd
, newname
, 0);
4442 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
4444 return sys_renameat2(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
4447 int vfs_whiteout(struct inode
*dir
, struct dentry
*dentry
)
4449 int error
= may_create(dir
, dentry
);
4453 if (!dir
->i_op
->mknod
)
4456 return dir
->i_op
->mknod(dir
, dentry
,
4457 S_IFCHR
| WHITEOUT_MODE
, WHITEOUT_DEV
);
4459 EXPORT_SYMBOL(vfs_whiteout
);
4461 int readlink_copy(char __user
*buffer
, int buflen
, const char *link
)
4463 int len
= PTR_ERR(link
);
4468 if (len
> (unsigned) buflen
)
4470 if (copy_to_user(buffer
, link
, len
))
4475 EXPORT_SYMBOL(readlink_copy
);
4478 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
4479 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
4480 * using) it for any given inode is up to filesystem.
4482 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4485 const char *link
= dentry
->d_inode
->i_link
;
4489 link
= dentry
->d_inode
->i_op
->follow_link(dentry
, &cookie
, NULL
);
4491 return PTR_ERR(link
);
4493 res
= readlink_copy(buffer
, buflen
, link
);
4494 if (cookie
&& dentry
->d_inode
->i_op
->put_link
)
4495 dentry
->d_inode
->i_op
->put_link(dentry
, cookie
);
4498 EXPORT_SYMBOL(generic_readlink
);
4500 /* get the link contents into pagecache */
4501 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
4505 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
4506 page
= read_mapping_page(mapping
, 0, NULL
);
4511 nd_terminate_link(kaddr
, dentry
->d_inode
->i_size
, PAGE_SIZE
- 1);
4515 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
4517 struct page
*page
= NULL
;
4518 int res
= readlink_copy(buffer
, buflen
, page_getlink(dentry
, &page
));
4521 page_cache_release(page
);
4525 EXPORT_SYMBOL(page_readlink
);
4527 const char *page_follow_link_light(struct dentry
*dentry
, void **cookie
, struct nameidata
*nd
)
4529 struct page
*page
= NULL
;
4530 char *res
= page_getlink(dentry
, &page
);
4535 EXPORT_SYMBOL(page_follow_link_light
);
4537 void page_put_link(struct dentry
*dentry
, void *cookie
)
4539 struct page
*page
= cookie
;
4541 page_cache_release(page
);
4543 EXPORT_SYMBOL(page_put_link
);
4546 * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
4548 int __page_symlink(struct inode
*inode
, const char *symname
, int len
, int nofs
)
4550 struct address_space
*mapping
= inode
->i_mapping
;
4555 unsigned int flags
= AOP_FLAG_UNINTERRUPTIBLE
;
4557 flags
|= AOP_FLAG_NOFS
;
4560 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
4561 flags
, &page
, &fsdata
);
4565 kaddr
= kmap_atomic(page
);
4566 memcpy(kaddr
, symname
, len
-1);
4567 kunmap_atomic(kaddr
);
4569 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
4576 mark_inode_dirty(inode
);
4581 EXPORT_SYMBOL(__page_symlink
);
4583 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
4585 return __page_symlink(inode
, symname
, len
,
4586 !(mapping_gfp_mask(inode
->i_mapping
) & __GFP_FS
));
4588 EXPORT_SYMBOL(page_symlink
);
4590 const struct inode_operations page_symlink_inode_operations
= {
4591 .readlink
= generic_readlink
,
4592 .follow_link
= page_follow_link_light
,
4593 .put_link
= page_put_link
,
4595 EXPORT_SYMBOL(page_symlink_inode_operations
);