1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 1991, 1992 Linus Torvalds
9 * Some corrections by tytso.
12 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
15 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
18 #include <linux/init.h>
19 #include <linux/export.h>
20 #include <linux/kernel.h>
21 #include <linux/slab.h>
23 #include <linux/filelock.h>
24 #include <linux/namei.h>
25 #include <linux/pagemap.h>
26 #include <linux/sched/mm.h>
27 #include <linux/fsnotify.h>
28 #include <linux/personality.h>
29 #include <linux/security.h>
30 #include <linux/ima.h>
31 #include <linux/syscalls.h>
32 #include <linux/mount.h>
33 #include <linux/audit.h>
34 #include <linux/capability.h>
35 #include <linux/file.h>
36 #include <linux/fcntl.h>
37 #include <linux/device_cgroup.h>
38 #include <linux/fs_struct.h>
39 #include <linux/posix_acl.h>
40 #include <linux/hash.h>
41 #include <linux/bitops.h>
42 #include <linux/init_task.h>
43 #include <linux/uaccess.h>
48 /* [Feb-1997 T. Schoebel-Theuer]
49 * Fundamental changes in the pathname lookup mechanisms (namei)
50 * were necessary because of omirr. The reason is that omirr needs
51 * to know the _real_ pathname, not the user-supplied one, in case
52 * of symlinks (and also when transname replacements occur).
54 * The new code replaces the old recursive symlink resolution with
55 * an iterative one (in case of non-nested symlink chains). It does
56 * this with calls to <fs>_follow_link().
57 * As a side effect, dir_namei(), _namei() and follow_link() are now
58 * replaced with a single function lookup_dentry() that can handle all
59 * the special cases of the former code.
61 * With the new dcache, the pathname is stored at each inode, at least as
62 * long as the refcount of the inode is positive. As a side effect, the
63 * size of the dcache depends on the inode cache and thus is dynamic.
65 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
66 * resolution to correspond with current state of the code.
68 * Note that the symlink resolution is not *completely* iterative.
69 * There is still a significant amount of tail- and mid- recursion in
70 * the algorithm. Also, note that <fs>_readlink() is not used in
71 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
72 * may return different results than <fs>_follow_link(). Many virtual
73 * filesystems (including /proc) exhibit this behavior.
76 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
77 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
78 * and the name already exists in form of a symlink, try to create the new
79 * name indicated by the symlink. The old code always complained that the
80 * name already exists, due to not following the symlink even if its target
81 * is nonexistent. The new semantics affects also mknod() and link() when
82 * the name is a symlink pointing to a non-existent name.
84 * I don't know which semantics is the right one, since I have no access
85 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
86 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
87 * "old" one. Personally, I think the new semantics is much more logical.
88 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
89 * file does succeed in both HP-UX and SunOs, but not in Solaris
90 * and in the old Linux semantics.
93 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
94 * semantics. See the comments in "open_namei" and "do_link" below.
96 * [10-Sep-98 Alan Modra] Another symlink change.
99 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
100 * inside the path - always follow.
101 * in the last component in creation/removal/renaming - never follow.
102 * if LOOKUP_FOLLOW passed - follow.
103 * if the pathname has trailing slashes - follow.
104 * otherwise - don't follow.
105 * (applied in that order).
107 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
108 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
109 * During the 2.4 we need to fix the userland stuff depending on it -
110 * hopefully we will be able to get rid of that wart in 2.5. So far only
111 * XEmacs seems to be relying on it...
114 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
115 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
116 * any extra contention...
119 /* In order to reduce some races, while at the same time doing additional
120 * checking and hopefully speeding things up, we copy filenames to the
121 * kernel data space before using them..
123 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
124 * PATH_MAX includes the nul terminator --RR.
127 #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname))
130 getname_flags(const char __user
*filename
, int flags
, int *empty
)
132 struct filename
*result
;
136 result
= audit_reusename(filename
);
140 result
= __getname();
141 if (unlikely(!result
))
142 return ERR_PTR(-ENOMEM
);
145 * First, try to embed the struct filename inside the names_cache
148 kname
= (char *)result
->iname
;
149 result
->name
= kname
;
151 len
= strncpy_from_user(kname
, filename
, EMBEDDED_NAME_MAX
);
152 if (unlikely(len
< 0)) {
158 * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
159 * separate struct filename so we can dedicate the entire
160 * names_cache allocation for the pathname, and re-do the copy from
163 if (unlikely(len
== EMBEDDED_NAME_MAX
)) {
164 const size_t size
= offsetof(struct filename
, iname
[1]);
165 kname
= (char *)result
;
168 * size is chosen that way we to guarantee that
169 * result->iname[0] is within the same object and that
170 * kname can't be equal to result->iname, no matter what.
172 result
= kzalloc(size
, GFP_KERNEL
);
173 if (unlikely(!result
)) {
175 return ERR_PTR(-ENOMEM
);
177 result
->name
= kname
;
178 len
= strncpy_from_user(kname
, filename
, PATH_MAX
);
179 if (unlikely(len
< 0)) {
184 if (unlikely(len
== PATH_MAX
)) {
187 return ERR_PTR(-ENAMETOOLONG
);
192 /* The empty path is special. */
193 if (unlikely(!len
)) {
196 if (!(flags
& LOOKUP_EMPTY
)) {
198 return ERR_PTR(-ENOENT
);
202 result
->uptr
= filename
;
203 result
->aname
= NULL
;
204 audit_getname(result
);
209 getname_uflags(const char __user
*filename
, int uflags
)
211 int flags
= (uflags
& AT_EMPTY_PATH
) ? LOOKUP_EMPTY
: 0;
213 return getname_flags(filename
, flags
, NULL
);
217 getname(const char __user
* filename
)
219 return getname_flags(filename
, 0, NULL
);
223 getname_kernel(const char * filename
)
225 struct filename
*result
;
226 int len
= strlen(filename
) + 1;
228 result
= __getname();
229 if (unlikely(!result
))
230 return ERR_PTR(-ENOMEM
);
232 if (len
<= EMBEDDED_NAME_MAX
) {
233 result
->name
= (char *)result
->iname
;
234 } else if (len
<= PATH_MAX
) {
235 const size_t size
= offsetof(struct filename
, iname
[1]);
236 struct filename
*tmp
;
238 tmp
= kmalloc(size
, GFP_KERNEL
);
239 if (unlikely(!tmp
)) {
241 return ERR_PTR(-ENOMEM
);
243 tmp
->name
= (char *)result
;
247 return ERR_PTR(-ENAMETOOLONG
);
249 memcpy((char *)result
->name
, filename
, len
);
251 result
->aname
= NULL
;
253 audit_getname(result
);
258 void putname(struct filename
*name
)
263 BUG_ON(name
->refcnt
<= 0);
265 if (--name
->refcnt
> 0)
268 if (name
->name
!= name
->iname
) {
269 __putname(name
->name
);
276 * check_acl - perform ACL permission checking
277 * @idmap: idmap of the mount the inode was found from
278 * @inode: inode to check permissions on
279 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...)
281 * This function performs the ACL permission checking. Since this function
282 * retrieve POSIX acls it needs to know whether it is called from a blocking or
283 * non-blocking context and thus cares about the MAY_NOT_BLOCK bit.
285 * If the inode has been found through an idmapped mount the idmap of
286 * the vfsmount must be passed through @idmap. This function will then take
287 * care to map the inode according to @idmap before checking permissions.
288 * On non-idmapped mounts or if permission checking is to be performed on the
289 * raw inode simply passs @nop_mnt_idmap.
291 static int check_acl(struct mnt_idmap
*idmap
,
292 struct inode
*inode
, int mask
)
294 #ifdef CONFIG_FS_POSIX_ACL
295 struct posix_acl
*acl
;
297 if (mask
& MAY_NOT_BLOCK
) {
298 acl
= get_cached_acl_rcu(inode
, ACL_TYPE_ACCESS
);
301 /* no ->get_inode_acl() calls in RCU mode... */
302 if (is_uncached_acl(acl
))
304 return posix_acl_permission(idmap
, inode
, acl
, mask
);
307 acl
= get_inode_acl(inode
, ACL_TYPE_ACCESS
);
311 int error
= posix_acl_permission(idmap
, inode
, acl
, mask
);
312 posix_acl_release(acl
);
321 * acl_permission_check - perform basic UNIX permission checking
322 * @idmap: idmap of the mount the inode was found from
323 * @inode: inode to check permissions on
324 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...)
326 * This function performs the basic UNIX permission checking. Since this
327 * function may retrieve POSIX acls it needs to know whether it is called from a
328 * blocking or non-blocking context and thus cares about the MAY_NOT_BLOCK bit.
330 * If the inode has been found through an idmapped mount the idmap of
331 * the vfsmount must be passed through @idmap. This function will then take
332 * care to map the inode according to @idmap before checking permissions.
333 * On non-idmapped mounts or if permission checking is to be performed on the
334 * raw inode simply passs @nop_mnt_idmap.
336 static int acl_permission_check(struct mnt_idmap
*idmap
,
337 struct inode
*inode
, int mask
)
339 unsigned int mode
= inode
->i_mode
;
342 /* Are we the owner? If so, ACL's don't matter */
343 vfsuid
= i_uid_into_vfsuid(idmap
, inode
);
344 if (likely(vfsuid_eq_kuid(vfsuid
, current_fsuid()))) {
347 return (mask
& ~mode
) ? -EACCES
: 0;
350 /* Do we have ACL's? */
351 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
)) {
352 int error
= check_acl(idmap
, inode
, mask
);
353 if (error
!= -EAGAIN
)
357 /* Only RWX matters for group/other mode bits */
361 * Are the group permissions different from
362 * the other permissions in the bits we care
363 * about? Need to check group ownership if so.
365 if (mask
& (mode
^ (mode
>> 3))) {
366 vfsgid_t vfsgid
= i_gid_into_vfsgid(idmap
, inode
);
367 if (vfsgid_in_group_p(vfsgid
))
371 /* Bits in 'mode' clear that we require? */
372 return (mask
& ~mode
) ? -EACCES
: 0;
376 * generic_permission - check for access rights on a Posix-like filesystem
377 * @idmap: idmap of the mount the inode was found from
378 * @inode: inode to check access rights for
379 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC,
380 * %MAY_NOT_BLOCK ...)
382 * Used to check for read/write/execute permissions on a file.
383 * We use "fsuid" for this, letting us set arbitrary permissions
384 * for filesystem access without changing the "normal" uids which
385 * are used for other things.
387 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
388 * request cannot be satisfied (eg. requires blocking or too much complexity).
389 * It would then be called again in ref-walk mode.
391 * If the inode has been found through an idmapped mount the idmap of
392 * the vfsmount must be passed through @idmap. This function will then take
393 * care to map the inode according to @idmap before checking permissions.
394 * On non-idmapped mounts or if permission checking is to be performed on the
395 * raw inode simply passs @nop_mnt_idmap.
397 int generic_permission(struct mnt_idmap
*idmap
, struct inode
*inode
,
403 * Do the basic permission checks.
405 ret
= acl_permission_check(idmap
, inode
, mask
);
409 if (S_ISDIR(inode
->i_mode
)) {
410 /* DACs are overridable for directories */
411 if (!(mask
& MAY_WRITE
))
412 if (capable_wrt_inode_uidgid(idmap
, inode
,
413 CAP_DAC_READ_SEARCH
))
415 if (capable_wrt_inode_uidgid(idmap
, inode
,
422 * Searching includes executable on directories, else just read.
424 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
425 if (mask
== MAY_READ
)
426 if (capable_wrt_inode_uidgid(idmap
, inode
,
427 CAP_DAC_READ_SEARCH
))
430 * Read/write DACs are always overridable.
431 * Executable DACs are overridable when there is
432 * at least one exec bit set.
434 if (!(mask
& MAY_EXEC
) || (inode
->i_mode
& S_IXUGO
))
435 if (capable_wrt_inode_uidgid(idmap
, inode
,
441 EXPORT_SYMBOL(generic_permission
);
444 * do_inode_permission - UNIX permission checking
445 * @idmap: idmap of the mount the inode was found from
446 * @inode: inode to check permissions on
447 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...)
449 * We _really_ want to just do "generic_permission()" without
450 * even looking at the inode->i_op values. So we keep a cache
451 * flag in inode->i_opflags, that says "this has not special
452 * permission function, use the fast case".
454 static inline int do_inode_permission(struct mnt_idmap
*idmap
,
455 struct inode
*inode
, int mask
)
457 if (unlikely(!(inode
->i_opflags
& IOP_FASTPERM
))) {
458 if (likely(inode
->i_op
->permission
))
459 return inode
->i_op
->permission(idmap
, inode
, mask
);
461 /* This gets set once for the inode lifetime */
462 spin_lock(&inode
->i_lock
);
463 inode
->i_opflags
|= IOP_FASTPERM
;
464 spin_unlock(&inode
->i_lock
);
466 return generic_permission(idmap
, inode
, mask
);
470 * sb_permission - Check superblock-level permissions
471 * @sb: Superblock of inode to check permission on
472 * @inode: Inode to check permission on
473 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
475 * Separate out file-system wide checks from inode-specific permission checks.
477 static int sb_permission(struct super_block
*sb
, struct inode
*inode
, int mask
)
479 if (unlikely(mask
& MAY_WRITE
)) {
480 umode_t mode
= inode
->i_mode
;
482 /* Nobody gets write access to a read-only fs. */
483 if (sb_rdonly(sb
) && (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
490 * inode_permission - Check for access rights to a given inode
491 * @idmap: idmap of the mount the inode was found from
492 * @inode: Inode to check permission on
493 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
495 * Check for read/write/execute permissions on an inode. We use fs[ug]id for
496 * this, letting us set arbitrary permissions for filesystem access without
497 * changing the "normal" UIDs which are used for other things.
499 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
501 int inode_permission(struct mnt_idmap
*idmap
,
502 struct inode
*inode
, int mask
)
506 retval
= sb_permission(inode
->i_sb
, inode
, mask
);
510 if (unlikely(mask
& MAY_WRITE
)) {
512 * Nobody gets write access to an immutable file.
514 if (IS_IMMUTABLE(inode
))
518 * Updating mtime will likely cause i_uid and i_gid to be
519 * written back improperly if their true value is unknown
522 if (HAS_UNMAPPED_ID(idmap
, inode
))
526 retval
= do_inode_permission(idmap
, inode
, mask
);
530 retval
= devcgroup_inode_permission(inode
, mask
);
534 return security_inode_permission(inode
, mask
);
536 EXPORT_SYMBOL(inode_permission
);
539 * path_get - get a reference to a path
540 * @path: path to get the reference to
542 * Given a path increment the reference count to the dentry and the vfsmount.
544 void path_get(const struct path
*path
)
549 EXPORT_SYMBOL(path_get
);
552 * path_put - put a reference to a path
553 * @path: path to put the reference to
555 * Given a path decrement the reference count to the dentry and the vfsmount.
557 void path_put(const struct path
*path
)
562 EXPORT_SYMBOL(path_put
);
564 #define EMBEDDED_LEVELS 2
569 struct inode
*inode
; /* path.dentry.d_inode */
570 unsigned int flags
, state
;
571 unsigned seq
, next_seq
, m_seq
, r_seq
;
574 int total_link_count
;
577 struct delayed_call done
;
580 } *stack
, internal
[EMBEDDED_LEVELS
];
581 struct filename
*name
;
582 struct nameidata
*saved
;
587 } __randomize_layout
;
589 #define ND_ROOT_PRESET 1
590 #define ND_ROOT_GRABBED 2
593 static void __set_nameidata(struct nameidata
*p
, int dfd
, struct filename
*name
)
595 struct nameidata
*old
= current
->nameidata
;
596 p
->stack
= p
->internal
;
601 p
->path
.dentry
= NULL
;
602 p
->total_link_count
= old
? old
->total_link_count
: 0;
604 current
->nameidata
= p
;
607 static inline void set_nameidata(struct nameidata
*p
, int dfd
, struct filename
*name
,
608 const struct path
*root
)
610 __set_nameidata(p
, dfd
, name
);
612 if (unlikely(root
)) {
613 p
->state
= ND_ROOT_PRESET
;
618 static void restore_nameidata(void)
620 struct nameidata
*now
= current
->nameidata
, *old
= now
->saved
;
622 current
->nameidata
= old
;
624 old
->total_link_count
= now
->total_link_count
;
625 if (now
->stack
!= now
->internal
)
629 static bool nd_alloc_stack(struct nameidata
*nd
)
633 p
= kmalloc_array(MAXSYMLINKS
, sizeof(struct saved
),
634 nd
->flags
& LOOKUP_RCU
? GFP_ATOMIC
: GFP_KERNEL
);
637 memcpy(p
, nd
->internal
, sizeof(nd
->internal
));
643 * path_connected - Verify that a dentry is below mnt.mnt_root
645 * Rename can sometimes move a file or directory outside of a bind
646 * mount, path_connected allows those cases to be detected.
648 static bool path_connected(struct vfsmount
*mnt
, struct dentry
*dentry
)
650 struct super_block
*sb
= mnt
->mnt_sb
;
652 /* Bind mounts can have disconnected paths */
653 if (mnt
->mnt_root
== sb
->s_root
)
656 return is_subdir(dentry
, mnt
->mnt_root
);
659 static void drop_links(struct nameidata
*nd
)
663 struct saved
*last
= nd
->stack
+ i
;
664 do_delayed_call(&last
->done
);
665 clear_delayed_call(&last
->done
);
669 static void leave_rcu(struct nameidata
*nd
)
671 nd
->flags
&= ~LOOKUP_RCU
;
672 nd
->seq
= nd
->next_seq
= 0;
676 static void terminate_walk(struct nameidata
*nd
)
679 if (!(nd
->flags
& LOOKUP_RCU
)) {
682 for (i
= 0; i
< nd
->depth
; i
++)
683 path_put(&nd
->stack
[i
].link
);
684 if (nd
->state
& ND_ROOT_GRABBED
) {
686 nd
->state
&= ~ND_ROOT_GRABBED
;
693 nd
->path
.dentry
= NULL
;
696 /* path_put is needed afterwards regardless of success or failure */
697 static bool __legitimize_path(struct path
*path
, unsigned seq
, unsigned mseq
)
699 int res
= __legitimize_mnt(path
->mnt
, mseq
);
706 if (unlikely(!lockref_get_not_dead(&path
->dentry
->d_lockref
))) {
710 return !read_seqcount_retry(&path
->dentry
->d_seq
, seq
);
713 static inline bool legitimize_path(struct nameidata
*nd
,
714 struct path
*path
, unsigned seq
)
716 return __legitimize_path(path
, seq
, nd
->m_seq
);
719 static bool legitimize_links(struct nameidata
*nd
)
722 if (unlikely(nd
->flags
& LOOKUP_CACHED
)) {
727 for (i
= 0; i
< nd
->depth
; i
++) {
728 struct saved
*last
= nd
->stack
+ i
;
729 if (unlikely(!legitimize_path(nd
, &last
->link
, last
->seq
))) {
738 static bool legitimize_root(struct nameidata
*nd
)
740 /* Nothing to do if nd->root is zero or is managed by the VFS user. */
741 if (!nd
->root
.mnt
|| (nd
->state
& ND_ROOT_PRESET
))
743 nd
->state
|= ND_ROOT_GRABBED
;
744 return legitimize_path(nd
, &nd
->root
, nd
->root_seq
);
748 * Path walking has 2 modes, rcu-walk and ref-walk (see
749 * Documentation/filesystems/path-lookup.txt). In situations when we can't
750 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
751 * normal reference counts on dentries and vfsmounts to transition to ref-walk
752 * mode. Refcounts are grabbed at the last known good point before rcu-walk
753 * got stuck, so ref-walk may continue from there. If this is not successful
754 * (eg. a seqcount has changed), then failure is returned and it's up to caller
755 * to restart the path walk from the beginning in ref-walk mode.
759 * try_to_unlazy - try to switch to ref-walk mode.
760 * @nd: nameidata pathwalk data
761 * Returns: true on success, false on failure
763 * try_to_unlazy attempts to legitimize the current nd->path and nd->root
765 * Must be called from rcu-walk context.
766 * Nothing should touch nameidata between try_to_unlazy() failure and
769 static bool try_to_unlazy(struct nameidata
*nd
)
771 struct dentry
*parent
= nd
->path
.dentry
;
773 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
775 if (unlikely(!legitimize_links(nd
)))
777 if (unlikely(!legitimize_path(nd
, &nd
->path
, nd
->seq
)))
779 if (unlikely(!legitimize_root(nd
)))
782 BUG_ON(nd
->inode
!= parent
->d_inode
);
787 nd
->path
.dentry
= NULL
;
794 * try_to_unlazy_next - try to switch to ref-walk mode.
795 * @nd: nameidata pathwalk data
796 * @dentry: next dentry to step into
797 * Returns: true on success, false on failure
799 * Similar to try_to_unlazy(), but here we have the next dentry already
800 * picked by rcu-walk and want to legitimize that in addition to the current
801 * nd->path and nd->root for ref-walk mode. Must be called from rcu-walk context.
802 * Nothing should touch nameidata between try_to_unlazy_next() failure and
805 static bool try_to_unlazy_next(struct nameidata
*nd
, struct dentry
*dentry
)
808 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
810 if (unlikely(!legitimize_links(nd
)))
812 res
= __legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
);
818 if (unlikely(!lockref_get_not_dead(&nd
->path
.dentry
->d_lockref
)))
822 * We need to move both the parent and the dentry from the RCU domain
823 * to be properly refcounted. And the sequence number in the dentry
824 * validates *both* dentry counters, since we checked the sequence
825 * number of the parent after we got the child sequence number. So we
826 * know the parent must still be valid if the child sequence number is
828 if (unlikely(!lockref_get_not_dead(&dentry
->d_lockref
)))
830 if (read_seqcount_retry(&dentry
->d_seq
, nd
->next_seq
))
833 * Sequence counts matched. Now make sure that the root is
834 * still valid and get it if required.
836 if (unlikely(!legitimize_root(nd
)))
844 nd
->path
.dentry
= NULL
;
854 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
856 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
))
857 return dentry
->d_op
->d_revalidate(dentry
, flags
);
863 * complete_walk - successful completion of path walk
864 * @nd: pointer nameidata
866 * If we had been in RCU mode, drop out of it and legitimize nd->path.
867 * Revalidate the final result, unless we'd already done that during
868 * the path walk or the filesystem doesn't ask for it. Return 0 on
869 * success, -error on failure. In case of failure caller does not
870 * need to drop nd->path.
872 static int complete_walk(struct nameidata
*nd
)
874 struct dentry
*dentry
= nd
->path
.dentry
;
877 if (nd
->flags
& LOOKUP_RCU
) {
879 * We don't want to zero nd->root for scoped-lookups or
880 * externally-managed nd->root.
882 if (!(nd
->state
& ND_ROOT_PRESET
))
883 if (!(nd
->flags
& LOOKUP_IS_SCOPED
))
885 nd
->flags
&= ~LOOKUP_CACHED
;
886 if (!try_to_unlazy(nd
))
890 if (unlikely(nd
->flags
& LOOKUP_IS_SCOPED
)) {
892 * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't
893 * ever step outside the root during lookup" and should already
894 * be guaranteed by the rest of namei, we want to avoid a namei
895 * BUG resulting in userspace being given a path that was not
896 * scoped within the root at some point during the lookup.
898 * So, do a final sanity-check to make sure that in the
899 * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED)
900 * we won't silently return an fd completely outside of the
901 * requested root to userspace.
903 * Userspace could move the path outside the root after this
904 * check, but as discussed elsewhere this is not a concern (the
905 * resolved file was inside the root at some point).
907 if (!path_is_under(&nd
->path
, &nd
->root
))
911 if (likely(!(nd
->state
& ND_JUMPED
)))
914 if (likely(!(dentry
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)))
917 status
= dentry
->d_op
->d_weak_revalidate(dentry
, nd
->flags
);
927 static int set_root(struct nameidata
*nd
)
929 struct fs_struct
*fs
= current
->fs
;
932 * Jumping to the real root in a scoped-lookup is a BUG in namei, but we
933 * still have to ensure it doesn't happen because it will cause a breakout
936 if (WARN_ON(nd
->flags
& LOOKUP_IS_SCOPED
))
937 return -ENOTRECOVERABLE
;
939 if (nd
->flags
& LOOKUP_RCU
) {
943 seq
= read_seqcount_begin(&fs
->seq
);
945 nd
->root_seq
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
946 } while (read_seqcount_retry(&fs
->seq
, seq
));
948 get_fs_root(fs
, &nd
->root
);
949 nd
->state
|= ND_ROOT_GRABBED
;
954 static int nd_jump_root(struct nameidata
*nd
)
956 if (unlikely(nd
->flags
& LOOKUP_BENEATH
))
958 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
)) {
959 /* Absolute path arguments to path_init() are allowed. */
960 if (nd
->path
.mnt
!= NULL
&& nd
->path
.mnt
!= nd
->root
.mnt
)
964 int error
= set_root(nd
);
968 if (nd
->flags
& LOOKUP_RCU
) {
972 nd
->inode
= d
->d_inode
;
973 nd
->seq
= nd
->root_seq
;
974 if (read_seqcount_retry(&d
->d_seq
, nd
->seq
))
980 nd
->inode
= nd
->path
.dentry
->d_inode
;
982 nd
->state
|= ND_JUMPED
;
987 * Helper to directly jump to a known parsed path from ->get_link,
988 * caller must have taken a reference to path beforehand.
990 int nd_jump_link(const struct path
*path
)
993 struct nameidata
*nd
= current
->nameidata
;
995 if (unlikely(nd
->flags
& LOOKUP_NO_MAGICLINKS
))
999 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
)) {
1000 if (nd
->path
.mnt
!= path
->mnt
)
1003 /* Not currently safe for scoped-lookups. */
1004 if (unlikely(nd
->flags
& LOOKUP_IS_SCOPED
))
1007 path_put(&nd
->path
);
1009 nd
->inode
= nd
->path
.dentry
->d_inode
;
1010 nd
->state
|= ND_JUMPED
;
1018 static inline void put_link(struct nameidata
*nd
)
1020 struct saved
*last
= nd
->stack
+ --nd
->depth
;
1021 do_delayed_call(&last
->done
);
1022 if (!(nd
->flags
& LOOKUP_RCU
))
1023 path_put(&last
->link
);
1026 static int sysctl_protected_symlinks __read_mostly
;
1027 static int sysctl_protected_hardlinks __read_mostly
;
1028 static int sysctl_protected_fifos __read_mostly
;
1029 static int sysctl_protected_regular __read_mostly
;
1031 #ifdef CONFIG_SYSCTL
1032 static struct ctl_table namei_sysctls
[] = {
1034 .procname
= "protected_symlinks",
1035 .data
= &sysctl_protected_symlinks
,
1036 .maxlen
= sizeof(int),
1038 .proc_handler
= proc_dointvec_minmax
,
1039 .extra1
= SYSCTL_ZERO
,
1040 .extra2
= SYSCTL_ONE
,
1043 .procname
= "protected_hardlinks",
1044 .data
= &sysctl_protected_hardlinks
,
1045 .maxlen
= sizeof(int),
1047 .proc_handler
= proc_dointvec_minmax
,
1048 .extra1
= SYSCTL_ZERO
,
1049 .extra2
= SYSCTL_ONE
,
1052 .procname
= "protected_fifos",
1053 .data
= &sysctl_protected_fifos
,
1054 .maxlen
= sizeof(int),
1056 .proc_handler
= proc_dointvec_minmax
,
1057 .extra1
= SYSCTL_ZERO
,
1058 .extra2
= SYSCTL_TWO
,
1061 .procname
= "protected_regular",
1062 .data
= &sysctl_protected_regular
,
1063 .maxlen
= sizeof(int),
1065 .proc_handler
= proc_dointvec_minmax
,
1066 .extra1
= SYSCTL_ZERO
,
1067 .extra2
= SYSCTL_TWO
,
1072 static int __init
init_fs_namei_sysctls(void)
1074 register_sysctl_init("fs", namei_sysctls
);
1077 fs_initcall(init_fs_namei_sysctls
);
1079 #endif /* CONFIG_SYSCTL */
1082 * may_follow_link - Check symlink following for unsafe situations
1083 * @nd: nameidata pathwalk data
1085 * In the case of the sysctl_protected_symlinks sysctl being enabled,
1086 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
1087 * in a sticky world-writable directory. This is to protect privileged
1088 * processes from failing races against path names that may change out
1089 * from under them by way of other users creating malicious symlinks.
1090 * It will permit symlinks to be followed only when outside a sticky
1091 * world-writable directory, or when the uid of the symlink and follower
1092 * match, or when the directory owner matches the symlink's owner.
1094 * Returns 0 if following the symlink is allowed, -ve on error.
1096 static inline int may_follow_link(struct nameidata
*nd
, const struct inode
*inode
)
1098 struct mnt_idmap
*idmap
;
1101 if (!sysctl_protected_symlinks
)
1104 idmap
= mnt_idmap(nd
->path
.mnt
);
1105 vfsuid
= i_uid_into_vfsuid(idmap
, inode
);
1106 /* Allowed if owner and follower match. */
1107 if (vfsuid_eq_kuid(vfsuid
, current_fsuid()))
1110 /* Allowed if parent directory not sticky and world-writable. */
1111 if ((nd
->dir_mode
& (S_ISVTX
|S_IWOTH
)) != (S_ISVTX
|S_IWOTH
))
1114 /* Allowed if parent directory and link owner match. */
1115 if (vfsuid_valid(nd
->dir_vfsuid
) && vfsuid_eq(nd
->dir_vfsuid
, vfsuid
))
1118 if (nd
->flags
& LOOKUP_RCU
)
1121 audit_inode(nd
->name
, nd
->stack
[0].link
.dentry
, 0);
1122 audit_log_path_denied(AUDIT_ANOM_LINK
, "follow_link");
1127 * safe_hardlink_source - Check for safe hardlink conditions
1128 * @idmap: idmap of the mount the inode was found from
1129 * @inode: the source inode to hardlink from
1131 * Return false if at least one of the following conditions:
1132 * - inode is not a regular file
1134 * - inode is setgid and group-exec
1135 * - access failure for read and write
1137 * Otherwise returns true.
1139 static bool safe_hardlink_source(struct mnt_idmap
*idmap
,
1140 struct inode
*inode
)
1142 umode_t mode
= inode
->i_mode
;
1144 /* Special files should not get pinned to the filesystem. */
1148 /* Setuid files should not get pinned to the filesystem. */
1152 /* Executable setgid files should not get pinned to the filesystem. */
1153 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
))
1156 /* Hardlinking to unreadable or unwritable sources is dangerous. */
1157 if (inode_permission(idmap
, inode
, MAY_READ
| MAY_WRITE
))
1164 * may_linkat - Check permissions for creating a hardlink
1165 * @idmap: idmap of the mount the inode was found from
1166 * @link: the source to hardlink from
1168 * Block hardlink when all of:
1169 * - sysctl_protected_hardlinks enabled
1170 * - fsuid does not match inode
1171 * - hardlink source is unsafe (see safe_hardlink_source() above)
1172 * - not CAP_FOWNER in a namespace with the inode owner uid mapped
1174 * If the inode has been found through an idmapped mount the idmap of
1175 * the vfsmount must be passed through @idmap. This function will then take
1176 * care to map the inode according to @idmap before checking permissions.
1177 * On non-idmapped mounts or if permission checking is to be performed on the
1178 * raw inode simply pass @nop_mnt_idmap.
1180 * Returns 0 if successful, -ve on error.
1182 int may_linkat(struct mnt_idmap
*idmap
, const struct path
*link
)
1184 struct inode
*inode
= link
->dentry
->d_inode
;
1186 /* Inode writeback is not safe when the uid or gid are invalid. */
1187 if (!vfsuid_valid(i_uid_into_vfsuid(idmap
, inode
)) ||
1188 !vfsgid_valid(i_gid_into_vfsgid(idmap
, inode
)))
1191 if (!sysctl_protected_hardlinks
)
1194 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
1195 * otherwise, it must be a safe source.
1197 if (safe_hardlink_source(idmap
, inode
) ||
1198 inode_owner_or_capable(idmap
, inode
))
1201 audit_log_path_denied(AUDIT_ANOM_LINK
, "linkat");
1206 * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory
1207 * should be allowed, or not, on files that already
1209 * @idmap: idmap of the mount the inode was found from
1210 * @nd: nameidata pathwalk data
1211 * @inode: the inode of the file to open
1213 * Block an O_CREAT open of a FIFO (or a regular file) when:
1214 * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled
1215 * - the file already exists
1216 * - we are in a sticky directory
1217 * - we don't own the file
1218 * - the owner of the directory doesn't own the file
1219 * - the directory is world writable
1220 * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2
1221 * the directory doesn't have to be world writable: being group writable will
1224 * If the inode has been found through an idmapped mount the idmap of
1225 * the vfsmount must be passed through @idmap. This function will then take
1226 * care to map the inode according to @idmap before checking permissions.
1227 * On non-idmapped mounts or if permission checking is to be performed on the
1228 * raw inode simply pass @nop_mnt_idmap.
1230 * Returns 0 if the open is allowed, -ve on error.
1232 static int may_create_in_sticky(struct mnt_idmap
*idmap
,
1233 struct nameidata
*nd
, struct inode
*const inode
)
1235 umode_t dir_mode
= nd
->dir_mode
;
1236 vfsuid_t dir_vfsuid
= nd
->dir_vfsuid
;
1238 if ((!sysctl_protected_fifos
&& S_ISFIFO(inode
->i_mode
)) ||
1239 (!sysctl_protected_regular
&& S_ISREG(inode
->i_mode
)) ||
1240 likely(!(dir_mode
& S_ISVTX
)) ||
1241 vfsuid_eq(i_uid_into_vfsuid(idmap
, inode
), dir_vfsuid
) ||
1242 vfsuid_eq_kuid(i_uid_into_vfsuid(idmap
, inode
), current_fsuid()))
1245 if (likely(dir_mode
& 0002) ||
1247 ((sysctl_protected_fifos
>= 2 && S_ISFIFO(inode
->i_mode
)) ||
1248 (sysctl_protected_regular
>= 2 && S_ISREG(inode
->i_mode
))))) {
1249 const char *operation
= S_ISFIFO(inode
->i_mode
) ?
1250 "sticky_create_fifo" :
1251 "sticky_create_regular";
1252 audit_log_path_denied(AUDIT_ANOM_CREAT
, operation
);
1259 * follow_up - Find the mountpoint of path's vfsmount
1261 * Given a path, find the mountpoint of its source file system.
1262 * Replace @path with the path of the mountpoint in the parent mount.
1265 * Return 1 if we went up a level and 0 if we were already at the
1268 int follow_up(struct path
*path
)
1270 struct mount
*mnt
= real_mount(path
->mnt
);
1271 struct mount
*parent
;
1272 struct dentry
*mountpoint
;
1274 read_seqlock_excl(&mount_lock
);
1275 parent
= mnt
->mnt_parent
;
1276 if (parent
== mnt
) {
1277 read_sequnlock_excl(&mount_lock
);
1280 mntget(&parent
->mnt
);
1281 mountpoint
= dget(mnt
->mnt_mountpoint
);
1282 read_sequnlock_excl(&mount_lock
);
1284 path
->dentry
= mountpoint
;
1286 path
->mnt
= &parent
->mnt
;
1289 EXPORT_SYMBOL(follow_up
);
1291 static bool choose_mountpoint_rcu(struct mount
*m
, const struct path
*root
,
1292 struct path
*path
, unsigned *seqp
)
1294 while (mnt_has_parent(m
)) {
1295 struct dentry
*mountpoint
= m
->mnt_mountpoint
;
1298 if (unlikely(root
->dentry
== mountpoint
&&
1299 root
->mnt
== &m
->mnt
))
1301 if (mountpoint
!= m
->mnt
.mnt_root
) {
1302 path
->mnt
= &m
->mnt
;
1303 path
->dentry
= mountpoint
;
1304 *seqp
= read_seqcount_begin(&mountpoint
->d_seq
);
1311 static bool choose_mountpoint(struct mount
*m
, const struct path
*root
,
1318 unsigned seq
, mseq
= read_seqbegin(&mount_lock
);
1320 found
= choose_mountpoint_rcu(m
, root
, path
, &seq
);
1321 if (unlikely(!found
)) {
1322 if (!read_seqretry(&mount_lock
, mseq
))
1325 if (likely(__legitimize_path(path
, seq
, mseq
)))
1337 * Perform an automount
1338 * - return -EISDIR to tell follow_managed() to stop and return the path we
1341 static int follow_automount(struct path
*path
, int *count
, unsigned lookup_flags
)
1343 struct dentry
*dentry
= path
->dentry
;
1345 /* We don't want to mount if someone's just doing a stat -
1346 * unless they're stat'ing a directory and appended a '/' to
1349 * We do, however, want to mount if someone wants to open or
1350 * create a file of any type under the mountpoint, wants to
1351 * traverse through the mountpoint or wants to open the
1352 * mounted directory. Also, autofs may mark negative dentries
1353 * as being automount points. These will need the attentions
1354 * of the daemon to instantiate them before they can be used.
1356 if (!(lookup_flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
1357 LOOKUP_OPEN
| LOOKUP_CREATE
| LOOKUP_AUTOMOUNT
)) &&
1361 if (count
&& (*count
)++ >= MAXSYMLINKS
)
1364 return finish_automount(dentry
->d_op
->d_automount(path
), path
);
1368 * mount traversal - out-of-line part. One note on ->d_flags accesses -
1369 * dentries are pinned but not locked here, so negative dentry can go
1370 * positive right under us. Use of smp_load_acquire() provides a barrier
1371 * sufficient for ->d_inode and ->d_flags consistency.
1373 static int __traverse_mounts(struct path
*path
, unsigned flags
, bool *jumped
,
1374 int *count
, unsigned lookup_flags
)
1376 struct vfsmount
*mnt
= path
->mnt
;
1377 bool need_mntput
= false;
1380 while (flags
& DCACHE_MANAGED_DENTRY
) {
1381 /* Allow the filesystem to manage the transit without i_mutex
1383 if (flags
& DCACHE_MANAGE_TRANSIT
) {
1384 ret
= path
->dentry
->d_op
->d_manage(path
, false);
1385 flags
= smp_load_acquire(&path
->dentry
->d_flags
);
1390 if (flags
& DCACHE_MOUNTED
) { // something's mounted on it..
1391 struct vfsmount
*mounted
= lookup_mnt(path
);
1392 if (mounted
) { // ... in our namespace
1396 path
->mnt
= mounted
;
1397 path
->dentry
= dget(mounted
->mnt_root
);
1398 // here we know it's positive
1399 flags
= path
->dentry
->d_flags
;
1405 if (!(flags
& DCACHE_NEED_AUTOMOUNT
))
1408 // uncovered automount point
1409 ret
= follow_automount(path
, count
, lookup_flags
);
1410 flags
= smp_load_acquire(&path
->dentry
->d_flags
);
1417 // possible if you race with several mount --move
1418 if (need_mntput
&& path
->mnt
== mnt
)
1420 if (!ret
&& unlikely(d_flags_negative(flags
)))
1422 *jumped
= need_mntput
;
1426 static inline int traverse_mounts(struct path
*path
, bool *jumped
,
1427 int *count
, unsigned lookup_flags
)
1429 unsigned flags
= smp_load_acquire(&path
->dentry
->d_flags
);
1432 if (likely(!(flags
& DCACHE_MANAGED_DENTRY
))) {
1434 if (unlikely(d_flags_negative(flags
)))
1438 return __traverse_mounts(path
, flags
, jumped
, count
, lookup_flags
);
1441 int follow_down_one(struct path
*path
)
1443 struct vfsmount
*mounted
;
1445 mounted
= lookup_mnt(path
);
1449 path
->mnt
= mounted
;
1450 path
->dentry
= dget(mounted
->mnt_root
);
1455 EXPORT_SYMBOL(follow_down_one
);
1458 * Follow down to the covering mount currently visible to userspace. At each
1459 * point, the filesystem owning that dentry may be queried as to whether the
1460 * caller is permitted to proceed or not.
1462 int follow_down(struct path
*path
, unsigned int flags
)
1464 struct vfsmount
*mnt
= path
->mnt
;
1466 int ret
= traverse_mounts(path
, &jumped
, NULL
, flags
);
1468 if (path
->mnt
!= mnt
)
1472 EXPORT_SYMBOL(follow_down
);
1475 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1476 * we meet a managed dentry that would need blocking.
1478 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
)
1480 struct dentry
*dentry
= path
->dentry
;
1481 unsigned int flags
= dentry
->d_flags
;
1483 if (likely(!(flags
& DCACHE_MANAGED_DENTRY
)))
1486 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
))
1491 * Don't forget we might have a non-mountpoint managed dentry
1492 * that wants to block transit.
1494 if (unlikely(flags
& DCACHE_MANAGE_TRANSIT
)) {
1495 int res
= dentry
->d_op
->d_manage(path
, true);
1497 return res
== -EISDIR
;
1498 flags
= dentry
->d_flags
;
1501 if (flags
& DCACHE_MOUNTED
) {
1502 struct mount
*mounted
= __lookup_mnt(path
->mnt
, dentry
);
1504 path
->mnt
= &mounted
->mnt
;
1505 dentry
= path
->dentry
= mounted
->mnt
.mnt_root
;
1506 nd
->state
|= ND_JUMPED
;
1507 nd
->next_seq
= read_seqcount_begin(&dentry
->d_seq
);
1508 flags
= dentry
->d_flags
;
1509 // makes sure that non-RCU pathwalk could reach
1511 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1515 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1518 return !(flags
& DCACHE_NEED_AUTOMOUNT
);
1522 static inline int handle_mounts(struct nameidata
*nd
, struct dentry
*dentry
,
1528 path
->mnt
= nd
->path
.mnt
;
1529 path
->dentry
= dentry
;
1530 if (nd
->flags
& LOOKUP_RCU
) {
1531 unsigned int seq
= nd
->next_seq
;
1532 if (likely(__follow_mount_rcu(nd
, path
)))
1534 // *path and nd->next_seq might've been clobbered
1535 path
->mnt
= nd
->path
.mnt
;
1536 path
->dentry
= dentry
;
1538 if (!try_to_unlazy_next(nd
, dentry
))
1541 ret
= traverse_mounts(path
, &jumped
, &nd
->total_link_count
, nd
->flags
);
1543 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
))
1546 nd
->state
|= ND_JUMPED
;
1548 if (unlikely(ret
)) {
1550 if (path
->mnt
!= nd
->path
.mnt
)
1557 * This looks up the name in dcache and possibly revalidates the found dentry.
1558 * NULL is returned if the dentry does not exist in the cache.
1560 static struct dentry
*lookup_dcache(const struct qstr
*name
,
1564 struct dentry
*dentry
= d_lookup(dir
, name
);
1566 int error
= d_revalidate(dentry
, flags
);
1567 if (unlikely(error
<= 0)) {
1569 d_invalidate(dentry
);
1571 return ERR_PTR(error
);
1578 * Parent directory has inode locked exclusive. This is one
1579 * and only case when ->lookup() gets called on non in-lookup
1580 * dentries - as the matter of fact, this only gets called
1581 * when directory is guaranteed to have no in-lookup children
1584 static struct dentry
*__lookup_hash(const struct qstr
*name
,
1585 struct dentry
*base
, unsigned int flags
)
1587 struct dentry
*dentry
= lookup_dcache(name
, base
, flags
);
1589 struct inode
*dir
= base
->d_inode
;
1594 /* Don't create child dentry for a dead directory. */
1595 if (unlikely(IS_DEADDIR(dir
)))
1596 return ERR_PTR(-ENOENT
);
1598 dentry
= d_alloc(base
, name
);
1599 if (unlikely(!dentry
))
1600 return ERR_PTR(-ENOMEM
);
1602 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1603 if (unlikely(old
)) {
1610 static struct dentry
*lookup_fast(struct nameidata
*nd
)
1612 struct dentry
*dentry
, *parent
= nd
->path
.dentry
;
1616 * Rename seqlock is not required here because in the off chance
1617 * of a false negative due to a concurrent rename, the caller is
1618 * going to fall back to non-racy lookup.
1620 if (nd
->flags
& LOOKUP_RCU
) {
1621 dentry
= __d_lookup_rcu(parent
, &nd
->last
, &nd
->next_seq
);
1622 if (unlikely(!dentry
)) {
1623 if (!try_to_unlazy(nd
))
1624 return ERR_PTR(-ECHILD
);
1629 * This sequence count validates that the parent had no
1630 * changes while we did the lookup of the dentry above.
1632 if (read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
1633 return ERR_PTR(-ECHILD
);
1635 status
= d_revalidate(dentry
, nd
->flags
);
1636 if (likely(status
> 0))
1638 if (!try_to_unlazy_next(nd
, dentry
))
1639 return ERR_PTR(-ECHILD
);
1640 if (status
== -ECHILD
)
1641 /* we'd been told to redo it in non-rcu mode */
1642 status
= d_revalidate(dentry
, nd
->flags
);
1644 dentry
= __d_lookup(parent
, &nd
->last
);
1645 if (unlikely(!dentry
))
1647 status
= d_revalidate(dentry
, nd
->flags
);
1649 if (unlikely(status
<= 0)) {
1651 d_invalidate(dentry
);
1653 return ERR_PTR(status
);
1658 /* Fast lookup failed, do it the slow way */
1659 static struct dentry
*__lookup_slow(const struct qstr
*name
,
1663 struct dentry
*dentry
, *old
;
1664 struct inode
*inode
= dir
->d_inode
;
1665 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq
);
1667 /* Don't go there if it's already dead */
1668 if (unlikely(IS_DEADDIR(inode
)))
1669 return ERR_PTR(-ENOENT
);
1671 dentry
= d_alloc_parallel(dir
, name
, &wq
);
1674 if (unlikely(!d_in_lookup(dentry
))) {
1675 int error
= d_revalidate(dentry
, flags
);
1676 if (unlikely(error
<= 0)) {
1678 d_invalidate(dentry
);
1683 dentry
= ERR_PTR(error
);
1686 old
= inode
->i_op
->lookup(inode
, dentry
, flags
);
1687 d_lookup_done(dentry
);
1688 if (unlikely(old
)) {
1696 static struct dentry
*lookup_slow(const struct qstr
*name
,
1700 struct inode
*inode
= dir
->d_inode
;
1702 inode_lock_shared(inode
);
1703 res
= __lookup_slow(name
, dir
, flags
);
1704 inode_unlock_shared(inode
);
1708 static inline int may_lookup(struct mnt_idmap
*idmap
,
1709 struct nameidata
*nd
)
1711 if (nd
->flags
& LOOKUP_RCU
) {
1712 int err
= inode_permission(idmap
, nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1713 if (err
!= -ECHILD
|| !try_to_unlazy(nd
))
1716 return inode_permission(idmap
, nd
->inode
, MAY_EXEC
);
1719 static int reserve_stack(struct nameidata
*nd
, struct path
*link
)
1721 if (unlikely(nd
->total_link_count
++ >= MAXSYMLINKS
))
1724 if (likely(nd
->depth
!= EMBEDDED_LEVELS
))
1726 if (likely(nd
->stack
!= nd
->internal
))
1728 if (likely(nd_alloc_stack(nd
)))
1731 if (nd
->flags
& LOOKUP_RCU
) {
1732 // we need to grab link before we do unlazy. And we can't skip
1733 // unlazy even if we fail to grab the link - cleanup needs it
1734 bool grabbed_link
= legitimize_path(nd
, link
, nd
->next_seq
);
1736 if (!try_to_unlazy(nd
) || !grabbed_link
)
1739 if (nd_alloc_stack(nd
))
1745 enum {WALK_TRAILING
= 1, WALK_MORE
= 2, WALK_NOFOLLOW
= 4};
1747 static const char *pick_link(struct nameidata
*nd
, struct path
*link
,
1748 struct inode
*inode
, int flags
)
1752 int error
= reserve_stack(nd
, link
);
1754 if (unlikely(error
)) {
1755 if (!(nd
->flags
& LOOKUP_RCU
))
1757 return ERR_PTR(error
);
1759 last
= nd
->stack
+ nd
->depth
++;
1761 clear_delayed_call(&last
->done
);
1762 last
->seq
= nd
->next_seq
;
1764 if (flags
& WALK_TRAILING
) {
1765 error
= may_follow_link(nd
, inode
);
1766 if (unlikely(error
))
1767 return ERR_PTR(error
);
1770 if (unlikely(nd
->flags
& LOOKUP_NO_SYMLINKS
) ||
1771 unlikely(link
->mnt
->mnt_flags
& MNT_NOSYMFOLLOW
))
1772 return ERR_PTR(-ELOOP
);
1774 if (!(nd
->flags
& LOOKUP_RCU
)) {
1775 touch_atime(&last
->link
);
1777 } else if (atime_needs_update(&last
->link
, inode
)) {
1778 if (!try_to_unlazy(nd
))
1779 return ERR_PTR(-ECHILD
);
1780 touch_atime(&last
->link
);
1783 error
= security_inode_follow_link(link
->dentry
, inode
,
1784 nd
->flags
& LOOKUP_RCU
);
1785 if (unlikely(error
))
1786 return ERR_PTR(error
);
1788 res
= READ_ONCE(inode
->i_link
);
1790 const char * (*get
)(struct dentry
*, struct inode
*,
1791 struct delayed_call
*);
1792 get
= inode
->i_op
->get_link
;
1793 if (nd
->flags
& LOOKUP_RCU
) {
1794 res
= get(NULL
, inode
, &last
->done
);
1795 if (res
== ERR_PTR(-ECHILD
) && try_to_unlazy(nd
))
1796 res
= get(link
->dentry
, inode
, &last
->done
);
1798 res
= get(link
->dentry
, inode
, &last
->done
);
1806 error
= nd_jump_root(nd
);
1807 if (unlikely(error
))
1808 return ERR_PTR(error
);
1809 while (unlikely(*++res
== '/'))
1814 all_done
: // pure jump
1820 * Do we need to follow links? We _really_ want to be able
1821 * to do this check without having to look at inode->i_op,
1822 * so we keep a cache of "no, this doesn't need follow_link"
1823 * for the common case.
1825 * NOTE: dentry must be what nd->next_seq had been sampled from.
1827 static const char *step_into(struct nameidata
*nd
, int flags
,
1828 struct dentry
*dentry
)
1831 struct inode
*inode
;
1832 int err
= handle_mounts(nd
, dentry
, &path
);
1835 return ERR_PTR(err
);
1836 inode
= path
.dentry
->d_inode
;
1837 if (likely(!d_is_symlink(path
.dentry
)) ||
1838 ((flags
& WALK_TRAILING
) && !(nd
->flags
& LOOKUP_FOLLOW
)) ||
1839 (flags
& WALK_NOFOLLOW
)) {
1840 /* not a symlink or should not follow */
1841 if (nd
->flags
& LOOKUP_RCU
) {
1842 if (read_seqcount_retry(&path
.dentry
->d_seq
, nd
->next_seq
))
1843 return ERR_PTR(-ECHILD
);
1844 if (unlikely(!inode
))
1845 return ERR_PTR(-ENOENT
);
1847 dput(nd
->path
.dentry
);
1848 if (nd
->path
.mnt
!= path
.mnt
)
1849 mntput(nd
->path
.mnt
);
1853 nd
->seq
= nd
->next_seq
;
1856 if (nd
->flags
& LOOKUP_RCU
) {
1857 /* make sure that d_is_symlink above matches inode */
1858 if (read_seqcount_retry(&path
.dentry
->d_seq
, nd
->next_seq
))
1859 return ERR_PTR(-ECHILD
);
1861 if (path
.mnt
== nd
->path
.mnt
)
1864 return pick_link(nd
, &path
, inode
, flags
);
1867 static struct dentry
*follow_dotdot_rcu(struct nameidata
*nd
)
1869 struct dentry
*parent
, *old
;
1871 if (path_equal(&nd
->path
, &nd
->root
))
1873 if (unlikely(nd
->path
.dentry
== nd
->path
.mnt
->mnt_root
)) {
1876 if (!choose_mountpoint_rcu(real_mount(nd
->path
.mnt
),
1877 &nd
->root
, &path
, &seq
))
1879 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
))
1880 return ERR_PTR(-ECHILD
);
1882 nd
->inode
= path
.dentry
->d_inode
;
1884 // makes sure that non-RCU pathwalk could reach this state
1885 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1886 return ERR_PTR(-ECHILD
);
1887 /* we know that mountpoint was pinned */
1889 old
= nd
->path
.dentry
;
1890 parent
= old
->d_parent
;
1891 nd
->next_seq
= read_seqcount_begin(&parent
->d_seq
);
1892 // makes sure that non-RCU pathwalk could reach this state
1893 if (read_seqcount_retry(&old
->d_seq
, nd
->seq
))
1894 return ERR_PTR(-ECHILD
);
1895 if (unlikely(!path_connected(nd
->path
.mnt
, parent
)))
1896 return ERR_PTR(-ECHILD
);
1899 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1900 return ERR_PTR(-ECHILD
);
1901 if (unlikely(nd
->flags
& LOOKUP_BENEATH
))
1902 return ERR_PTR(-ECHILD
);
1903 nd
->next_seq
= nd
->seq
;
1904 return nd
->path
.dentry
;
1907 static struct dentry
*follow_dotdot(struct nameidata
*nd
)
1909 struct dentry
*parent
;
1911 if (path_equal(&nd
->path
, &nd
->root
))
1913 if (unlikely(nd
->path
.dentry
== nd
->path
.mnt
->mnt_root
)) {
1916 if (!choose_mountpoint(real_mount(nd
->path
.mnt
),
1919 path_put(&nd
->path
);
1921 nd
->inode
= path
.dentry
->d_inode
;
1922 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
))
1923 return ERR_PTR(-EXDEV
);
1925 /* rare case of legitimate dget_parent()... */
1926 parent
= dget_parent(nd
->path
.dentry
);
1927 if (unlikely(!path_connected(nd
->path
.mnt
, parent
))) {
1929 return ERR_PTR(-ENOENT
);
1934 if (unlikely(nd
->flags
& LOOKUP_BENEATH
))
1935 return ERR_PTR(-EXDEV
);
1936 return dget(nd
->path
.dentry
);
1939 static const char *handle_dots(struct nameidata
*nd
, int type
)
1941 if (type
== LAST_DOTDOT
) {
1942 const char *error
= NULL
;
1943 struct dentry
*parent
;
1945 if (!nd
->root
.mnt
) {
1946 error
= ERR_PTR(set_root(nd
));
1950 if (nd
->flags
& LOOKUP_RCU
)
1951 parent
= follow_dotdot_rcu(nd
);
1953 parent
= follow_dotdot(nd
);
1955 return ERR_CAST(parent
);
1956 error
= step_into(nd
, WALK_NOFOLLOW
, parent
);
1957 if (unlikely(error
))
1960 if (unlikely(nd
->flags
& LOOKUP_IS_SCOPED
)) {
1962 * If there was a racing rename or mount along our
1963 * path, then we can't be sure that ".." hasn't jumped
1964 * above nd->root (and so userspace should retry or use
1968 if (__read_seqcount_retry(&mount_lock
.seqcount
, nd
->m_seq
))
1969 return ERR_PTR(-EAGAIN
);
1970 if (__read_seqcount_retry(&rename_lock
.seqcount
, nd
->r_seq
))
1971 return ERR_PTR(-EAGAIN
);
1977 static const char *walk_component(struct nameidata
*nd
, int flags
)
1979 struct dentry
*dentry
;
1981 * "." and ".." are special - ".." especially so because it has
1982 * to be able to know about the current root directory and
1983 * parent relationships.
1985 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
1986 if (!(flags
& WALK_MORE
) && nd
->depth
)
1988 return handle_dots(nd
, nd
->last_type
);
1990 dentry
= lookup_fast(nd
);
1992 return ERR_CAST(dentry
);
1993 if (unlikely(!dentry
)) {
1994 dentry
= lookup_slow(&nd
->last
, nd
->path
.dentry
, nd
->flags
);
1996 return ERR_CAST(dentry
);
1998 if (!(flags
& WALK_MORE
) && nd
->depth
)
2000 return step_into(nd
, flags
, dentry
);
2004 * We can do the critical dentry name comparison and hashing
2005 * operations one word at a time, but we are limited to:
2007 * - Architectures with fast unaligned word accesses. We could
2008 * do a "get_unaligned()" if this helps and is sufficiently
2011 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
2012 * do not trap on the (extremely unlikely) case of a page
2013 * crossing operation.
2015 * - Furthermore, we need an efficient 64-bit compile for the
2016 * 64-bit case in order to generate the "number of bytes in
2017 * the final mask". Again, that could be replaced with a
2018 * efficient population count instruction or similar.
2020 #ifdef CONFIG_DCACHE_WORD_ACCESS
2022 #include <asm/word-at-a-time.h>
2026 /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */
2028 #elif defined(CONFIG_64BIT)
2030 * Register pressure in the mixing function is an issue, particularly
2031 * on 32-bit x86, but almost any function requires one state value and
2032 * one temporary. Instead, use a function designed for two state values
2033 * and no temporaries.
2035 * This function cannot create a collision in only two iterations, so
2036 * we have two iterations to achieve avalanche. In those two iterations,
2037 * we have six layers of mixing, which is enough to spread one bit's
2038 * influence out to 2^6 = 64 state bits.
2040 * Rotate constants are scored by considering either 64 one-bit input
2041 * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the
2042 * probability of that delta causing a change to each of the 128 output
2043 * bits, using a sample of random initial states.
2045 * The Shannon entropy of the computed probabilities is then summed
2046 * to produce a score. Ideally, any input change has a 50% chance of
2047 * toggling any given output bit.
2049 * Mixing scores (in bits) for (12,45):
2050 * Input delta: 1-bit 2-bit
2051 * 1 round: 713.3 42542.6
2052 * 2 rounds: 2753.7 140389.8
2053 * 3 rounds: 5954.1 233458.2
2054 * 4 rounds: 7862.6 256672.2
2055 * Perfect: 8192 258048
2056 * (64*128) (64*63/2 * 128)
2058 #define HASH_MIX(x, y, a) \
2060 y ^= x, x = rol64(x,12),\
2061 x += y, y = rol64(y,45),\
2065 * Fold two longs into one 32-bit hash value. This must be fast, but
2066 * latency isn't quite as critical, as there is a fair bit of additional
2067 * work done before the hash value is used.
2069 static inline unsigned int fold_hash(unsigned long x
, unsigned long y
)
2071 y
^= x
* GOLDEN_RATIO_64
;
2072 y
*= GOLDEN_RATIO_64
;
2076 #else /* 32-bit case */
2079 * Mixing scores (in bits) for (7,20):
2080 * Input delta: 1-bit 2-bit
2081 * 1 round: 330.3 9201.6
2082 * 2 rounds: 1246.4 25475.4
2083 * 3 rounds: 1907.1 31295.1
2084 * 4 rounds: 2042.3 31718.6
2085 * Perfect: 2048 31744
2086 * (32*64) (32*31/2 * 64)
2088 #define HASH_MIX(x, y, a) \
2090 y ^= x, x = rol32(x, 7),\
2091 x += y, y = rol32(y,20),\
2094 static inline unsigned int fold_hash(unsigned long x
, unsigned long y
)
2096 /* Use arch-optimized multiply if one exists */
2097 return __hash_32(y
^ __hash_32(x
));
2103 * Return the hash of a string of known length. This is carfully
2104 * designed to match hash_name(), which is the more critical function.
2105 * In particular, we must end by hashing a final word containing 0..7
2106 * payload bytes, to match the way that hash_name() iterates until it
2107 * finds the delimiter after the name.
2109 unsigned int full_name_hash(const void *salt
, const char *name
, unsigned int len
)
2111 unsigned long a
, x
= 0, y
= (unsigned long)salt
;
2116 a
= load_unaligned_zeropad(name
);
2117 if (len
< sizeof(unsigned long))
2120 name
+= sizeof(unsigned long);
2121 len
-= sizeof(unsigned long);
2123 x
^= a
& bytemask_from_count(len
);
2125 return fold_hash(x
, y
);
2127 EXPORT_SYMBOL(full_name_hash
);
2129 /* Return the "hash_len" (hash and length) of a null-terminated string */
2130 u64
hashlen_string(const void *salt
, const char *name
)
2132 unsigned long a
= 0, x
= 0, y
= (unsigned long)salt
;
2133 unsigned long adata
, mask
, len
;
2134 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
2141 len
+= sizeof(unsigned long);
2143 a
= load_unaligned_zeropad(name
+len
);
2144 } while (!has_zero(a
, &adata
, &constants
));
2146 adata
= prep_zero_mask(a
, adata
, &constants
);
2147 mask
= create_zero_mask(adata
);
2148 x
^= a
& zero_bytemask(mask
);
2150 return hashlen_create(fold_hash(x
, y
), len
+ find_zero(mask
));
2152 EXPORT_SYMBOL(hashlen_string
);
2155 * Calculate the length and hash of the path component, and
2156 * return the "hash_len" as the result.
2158 static inline u64
hash_name(const void *salt
, const char *name
)
2160 unsigned long a
= 0, b
, x
= 0, y
= (unsigned long)salt
;
2161 unsigned long adata
, bdata
, mask
, len
;
2162 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
2169 len
+= sizeof(unsigned long);
2171 a
= load_unaligned_zeropad(name
+len
);
2172 b
= a
^ REPEAT_BYTE('/');
2173 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
2175 adata
= prep_zero_mask(a
, adata
, &constants
);
2176 bdata
= prep_zero_mask(b
, bdata
, &constants
);
2177 mask
= create_zero_mask(adata
| bdata
);
2178 x
^= a
& zero_bytemask(mask
);
2180 return hashlen_create(fold_hash(x
, y
), len
+ find_zero(mask
));
2183 #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */
2185 /* Return the hash of a string of known length */
2186 unsigned int full_name_hash(const void *salt
, const char *name
, unsigned int len
)
2188 unsigned long hash
= init_name_hash(salt
);
2190 hash
= partial_name_hash((unsigned char)*name
++, hash
);
2191 return end_name_hash(hash
);
2193 EXPORT_SYMBOL(full_name_hash
);
2195 /* Return the "hash_len" (hash and length) of a null-terminated string */
2196 u64
hashlen_string(const void *salt
, const char *name
)
2198 unsigned long hash
= init_name_hash(salt
);
2199 unsigned long len
= 0, c
;
2201 c
= (unsigned char)*name
;
2204 hash
= partial_name_hash(c
, hash
);
2205 c
= (unsigned char)name
[len
];
2207 return hashlen_create(end_name_hash(hash
), len
);
2209 EXPORT_SYMBOL(hashlen_string
);
2212 * We know there's a real path component here of at least
2215 static inline u64
hash_name(const void *salt
, const char *name
)
2217 unsigned long hash
= init_name_hash(salt
);
2218 unsigned long len
= 0, c
;
2220 c
= (unsigned char)*name
;
2223 hash
= partial_name_hash(c
, hash
);
2224 c
= (unsigned char)name
[len
];
2225 } while (c
&& c
!= '/');
2226 return hashlen_create(end_name_hash(hash
), len
);
2233 * This is the basic name resolution function, turning a pathname into
2234 * the final dentry. We expect 'base' to be positive and a directory.
2236 * Returns 0 and nd will have valid dentry and mnt on success.
2237 * Returns error and drops reference to input namei data on failure.
2239 static int link_path_walk(const char *name
, struct nameidata
*nd
)
2241 int depth
= 0; // depth <= nd->depth
2244 nd
->last_type
= LAST_ROOT
;
2245 nd
->flags
|= LOOKUP_PARENT
;
2247 return PTR_ERR(name
);
2251 nd
->dir_mode
= 0; // short-circuit the 'hardening' idiocy
2255 /* At this point we know we have a real path component. */
2257 struct mnt_idmap
*idmap
;
2262 idmap
= mnt_idmap(nd
->path
.mnt
);
2263 err
= may_lookup(idmap
, nd
);
2267 hash_len
= hash_name(nd
->path
.dentry
, name
);
2270 if (name
[0] == '.') switch (hashlen_len(hash_len
)) {
2272 if (name
[1] == '.') {
2274 nd
->state
|= ND_JUMPED
;
2280 if (likely(type
== LAST_NORM
)) {
2281 struct dentry
*parent
= nd
->path
.dentry
;
2282 nd
->state
&= ~ND_JUMPED
;
2283 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
2284 struct qstr
this = { { .hash_len
= hash_len
}, .name
= name
};
2285 err
= parent
->d_op
->d_hash(parent
, &this);
2288 hash_len
= this.hash_len
;
2293 nd
->last
.hash_len
= hash_len
;
2294 nd
->last
.name
= name
;
2295 nd
->last_type
= type
;
2297 name
+= hashlen_len(hash_len
);
2301 * If it wasn't NUL, we know it was '/'. Skip that
2302 * slash, and continue until no more slashes.
2306 } while (unlikely(*name
== '/'));
2307 if (unlikely(!*name
)) {
2309 /* pathname or trailing symlink, done */
2311 nd
->dir_vfsuid
= i_uid_into_vfsuid(idmap
, nd
->inode
);
2312 nd
->dir_mode
= nd
->inode
->i_mode
;
2313 nd
->flags
&= ~LOOKUP_PARENT
;
2316 /* last component of nested symlink */
2317 name
= nd
->stack
[--depth
].name
;
2318 link
= walk_component(nd
, 0);
2320 /* not the last component */
2321 link
= walk_component(nd
, WALK_MORE
);
2323 if (unlikely(link
)) {
2325 return PTR_ERR(link
);
2326 /* a symlink to follow */
2327 nd
->stack
[depth
++].name
= name
;
2331 if (unlikely(!d_can_lookup(nd
->path
.dentry
))) {
2332 if (nd
->flags
& LOOKUP_RCU
) {
2333 if (!try_to_unlazy(nd
))
2341 /* must be paired with terminate_walk() */
2342 static const char *path_init(struct nameidata
*nd
, unsigned flags
)
2345 const char *s
= nd
->name
->name
;
2347 /* LOOKUP_CACHED requires RCU, ask caller to retry */
2348 if ((flags
& (LOOKUP_RCU
| LOOKUP_CACHED
)) == LOOKUP_CACHED
)
2349 return ERR_PTR(-EAGAIN
);
2352 flags
&= ~LOOKUP_RCU
;
2353 if (flags
& LOOKUP_RCU
)
2356 nd
->seq
= nd
->next_seq
= 0;
2359 nd
->state
|= ND_JUMPED
;
2361 nd
->m_seq
= __read_seqcount_begin(&mount_lock
.seqcount
);
2362 nd
->r_seq
= __read_seqcount_begin(&rename_lock
.seqcount
);
2365 if (nd
->state
& ND_ROOT_PRESET
) {
2366 struct dentry
*root
= nd
->root
.dentry
;
2367 struct inode
*inode
= root
->d_inode
;
2368 if (*s
&& unlikely(!d_can_lookup(root
)))
2369 return ERR_PTR(-ENOTDIR
);
2370 nd
->path
= nd
->root
;
2372 if (flags
& LOOKUP_RCU
) {
2373 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2374 nd
->root_seq
= nd
->seq
;
2376 path_get(&nd
->path
);
2381 nd
->root
.mnt
= NULL
;
2383 /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */
2384 if (*s
== '/' && !(flags
& LOOKUP_IN_ROOT
)) {
2385 error
= nd_jump_root(nd
);
2386 if (unlikely(error
))
2387 return ERR_PTR(error
);
2391 /* Relative pathname -- get the starting-point it is relative to. */
2392 if (nd
->dfd
== AT_FDCWD
) {
2393 if (flags
& LOOKUP_RCU
) {
2394 struct fs_struct
*fs
= current
->fs
;
2398 seq
= read_seqcount_begin(&fs
->seq
);
2400 nd
->inode
= nd
->path
.dentry
->d_inode
;
2401 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2402 } while (read_seqcount_retry(&fs
->seq
, seq
));
2404 get_fs_pwd(current
->fs
, &nd
->path
);
2405 nd
->inode
= nd
->path
.dentry
->d_inode
;
2408 /* Caller must check execute permissions on the starting path component */
2409 struct fd f
= fdget_raw(nd
->dfd
);
2410 struct dentry
*dentry
;
2413 return ERR_PTR(-EBADF
);
2415 dentry
= f
.file
->f_path
.dentry
;
2417 if (*s
&& unlikely(!d_can_lookup(dentry
))) {
2419 return ERR_PTR(-ENOTDIR
);
2422 nd
->path
= f
.file
->f_path
;
2423 if (flags
& LOOKUP_RCU
) {
2424 nd
->inode
= nd
->path
.dentry
->d_inode
;
2425 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2427 path_get(&nd
->path
);
2428 nd
->inode
= nd
->path
.dentry
->d_inode
;
2433 /* For scoped-lookups we need to set the root to the dirfd as well. */
2434 if (flags
& LOOKUP_IS_SCOPED
) {
2435 nd
->root
= nd
->path
;
2436 if (flags
& LOOKUP_RCU
) {
2437 nd
->root_seq
= nd
->seq
;
2439 path_get(&nd
->root
);
2440 nd
->state
|= ND_ROOT_GRABBED
;
2446 static inline const char *lookup_last(struct nameidata
*nd
)
2448 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
2449 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2451 return walk_component(nd
, WALK_TRAILING
);
2454 static int handle_lookup_down(struct nameidata
*nd
)
2456 if (!(nd
->flags
& LOOKUP_RCU
))
2457 dget(nd
->path
.dentry
);
2458 nd
->next_seq
= nd
->seq
;
2459 return PTR_ERR(step_into(nd
, WALK_NOFOLLOW
, nd
->path
.dentry
));
2462 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2463 static int path_lookupat(struct nameidata
*nd
, unsigned flags
, struct path
*path
)
2465 const char *s
= path_init(nd
, flags
);
2468 if (unlikely(flags
& LOOKUP_DOWN
) && !IS_ERR(s
)) {
2469 err
= handle_lookup_down(nd
);
2470 if (unlikely(err
< 0))
2474 while (!(err
= link_path_walk(s
, nd
)) &&
2475 (s
= lookup_last(nd
)) != NULL
)
2477 if (!err
&& unlikely(nd
->flags
& LOOKUP_MOUNTPOINT
)) {
2478 err
= handle_lookup_down(nd
);
2479 nd
->state
&= ~ND_JUMPED
; // no d_weak_revalidate(), please...
2482 err
= complete_walk(nd
);
2484 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
)
2485 if (!d_can_lookup(nd
->path
.dentry
))
2489 nd
->path
.mnt
= NULL
;
2490 nd
->path
.dentry
= NULL
;
2496 int filename_lookup(int dfd
, struct filename
*name
, unsigned flags
,
2497 struct path
*path
, struct path
*root
)
2500 struct nameidata nd
;
2502 return PTR_ERR(name
);
2503 set_nameidata(&nd
, dfd
, name
, root
);
2504 retval
= path_lookupat(&nd
, flags
| LOOKUP_RCU
, path
);
2505 if (unlikely(retval
== -ECHILD
))
2506 retval
= path_lookupat(&nd
, flags
, path
);
2507 if (unlikely(retval
== -ESTALE
))
2508 retval
= path_lookupat(&nd
, flags
| LOOKUP_REVAL
, path
);
2510 if (likely(!retval
))
2511 audit_inode(name
, path
->dentry
,
2512 flags
& LOOKUP_MOUNTPOINT
? AUDIT_INODE_NOEVAL
: 0);
2513 restore_nameidata();
2517 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2518 static int path_parentat(struct nameidata
*nd
, unsigned flags
,
2519 struct path
*parent
)
2521 const char *s
= path_init(nd
, flags
);
2522 int err
= link_path_walk(s
, nd
);
2524 err
= complete_walk(nd
);
2527 nd
->path
.mnt
= NULL
;
2528 nd
->path
.dentry
= NULL
;
2534 /* Note: this does not consume "name" */
2535 static int filename_parentat(int dfd
, struct filename
*name
,
2536 unsigned int flags
, struct path
*parent
,
2537 struct qstr
*last
, int *type
)
2540 struct nameidata nd
;
2543 return PTR_ERR(name
);
2544 set_nameidata(&nd
, dfd
, name
, NULL
);
2545 retval
= path_parentat(&nd
, flags
| LOOKUP_RCU
, parent
);
2546 if (unlikely(retval
== -ECHILD
))
2547 retval
= path_parentat(&nd
, flags
, parent
);
2548 if (unlikely(retval
== -ESTALE
))
2549 retval
= path_parentat(&nd
, flags
| LOOKUP_REVAL
, parent
);
2550 if (likely(!retval
)) {
2552 *type
= nd
.last_type
;
2553 audit_inode(name
, parent
->dentry
, AUDIT_INODE_PARENT
);
2555 restore_nameidata();
2559 /* does lookup, returns the object with parent locked */
2560 static struct dentry
*__kern_path_locked(struct filename
*name
, struct path
*path
)
2566 error
= filename_parentat(AT_FDCWD
, name
, 0, path
, &last
, &type
);
2568 return ERR_PTR(error
);
2569 if (unlikely(type
!= LAST_NORM
)) {
2571 return ERR_PTR(-EINVAL
);
2573 inode_lock_nested(path
->dentry
->d_inode
, I_MUTEX_PARENT
);
2574 d
= __lookup_hash(&last
, path
->dentry
, 0);
2576 inode_unlock(path
->dentry
->d_inode
);
2582 struct dentry
*kern_path_locked(const char *name
, struct path
*path
)
2584 struct filename
*filename
= getname_kernel(name
);
2585 struct dentry
*res
= __kern_path_locked(filename
, path
);
2591 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
2593 struct filename
*filename
= getname_kernel(name
);
2594 int ret
= filename_lookup(AT_FDCWD
, filename
, flags
, path
, NULL
);
2600 EXPORT_SYMBOL(kern_path
);
2603 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2604 * @dentry: pointer to dentry of the base directory
2605 * @mnt: pointer to vfs mount of the base directory
2606 * @name: pointer to file name
2607 * @flags: lookup flags
2608 * @path: pointer to struct path to fill
2610 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
2611 const char *name
, unsigned int flags
,
2614 struct filename
*filename
;
2615 struct path root
= {.mnt
= mnt
, .dentry
= dentry
};
2618 filename
= getname_kernel(name
);
2619 /* the first argument of filename_lookup() is ignored with root */
2620 ret
= filename_lookup(AT_FDCWD
, filename
, flags
, path
, &root
);
2624 EXPORT_SYMBOL(vfs_path_lookup
);
2626 static int lookup_one_common(struct mnt_idmap
*idmap
,
2627 const char *name
, struct dentry
*base
, int len
,
2632 this->hash
= full_name_hash(base
, name
, len
);
2636 if (unlikely(name
[0] == '.')) {
2637 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2642 unsigned int c
= *(const unsigned char *)name
++;
2643 if (c
== '/' || c
== '\0')
2647 * See if the low-level filesystem might want
2648 * to use its own hash..
2650 if (base
->d_flags
& DCACHE_OP_HASH
) {
2651 int err
= base
->d_op
->d_hash(base
, this);
2656 return inode_permission(idmap
, base
->d_inode
, MAY_EXEC
);
2660 * try_lookup_one_len - filesystem helper to lookup single pathname component
2661 * @name: pathname component to lookup
2662 * @base: base directory to lookup from
2663 * @len: maximum length @len should be interpreted to
2665 * Look up a dentry by name in the dcache, returning NULL if it does not
2666 * currently exist. The function does not try to create a dentry.
2668 * Note that this routine is purely a helper for filesystem usage and should
2669 * not be called by generic code.
2671 * The caller must hold base->i_mutex.
2673 struct dentry
*try_lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2678 WARN_ON_ONCE(!inode_is_locked(base
->d_inode
));
2680 err
= lookup_one_common(&nop_mnt_idmap
, name
, base
, len
, &this);
2682 return ERR_PTR(err
);
2684 return lookup_dcache(&this, base
, 0);
2686 EXPORT_SYMBOL(try_lookup_one_len
);
2689 * lookup_one_len - filesystem helper to lookup single pathname component
2690 * @name: pathname component to lookup
2691 * @base: base directory to lookup from
2692 * @len: maximum length @len should be interpreted to
2694 * Note that this routine is purely a helper for filesystem usage and should
2695 * not be called by generic code.
2697 * The caller must hold base->i_mutex.
2699 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2701 struct dentry
*dentry
;
2705 WARN_ON_ONCE(!inode_is_locked(base
->d_inode
));
2707 err
= lookup_one_common(&nop_mnt_idmap
, name
, base
, len
, &this);
2709 return ERR_PTR(err
);
2711 dentry
= lookup_dcache(&this, base
, 0);
2712 return dentry
? dentry
: __lookup_slow(&this, base
, 0);
2714 EXPORT_SYMBOL(lookup_one_len
);
2717 * lookup_one - filesystem helper to lookup single pathname component
2718 * @idmap: idmap of the mount the lookup is performed from
2719 * @name: pathname component to lookup
2720 * @base: base directory to lookup from
2721 * @len: maximum length @len should be interpreted to
2723 * Note that this routine is purely a helper for filesystem usage and should
2724 * not be called by generic code.
2726 * The caller must hold base->i_mutex.
2728 struct dentry
*lookup_one(struct mnt_idmap
*idmap
, const char *name
,
2729 struct dentry
*base
, int len
)
2731 struct dentry
*dentry
;
2735 WARN_ON_ONCE(!inode_is_locked(base
->d_inode
));
2737 err
= lookup_one_common(idmap
, name
, base
, len
, &this);
2739 return ERR_PTR(err
);
2741 dentry
= lookup_dcache(&this, base
, 0);
2742 return dentry
? dentry
: __lookup_slow(&this, base
, 0);
2744 EXPORT_SYMBOL(lookup_one
);
2747 * lookup_one_unlocked - filesystem helper to lookup single pathname component
2748 * @idmap: idmap of the mount the lookup is performed from
2749 * @name: pathname component to lookup
2750 * @base: base directory to lookup from
2751 * @len: maximum length @len should be interpreted to
2753 * Note that this routine is purely a helper for filesystem usage and should
2754 * not be called by generic code.
2756 * Unlike lookup_one_len, it should be called without the parent
2757 * i_mutex held, and will take the i_mutex itself if necessary.
2759 struct dentry
*lookup_one_unlocked(struct mnt_idmap
*idmap
,
2760 const char *name
, struct dentry
*base
,
2767 err
= lookup_one_common(idmap
, name
, base
, len
, &this);
2769 return ERR_PTR(err
);
2771 ret
= lookup_dcache(&this, base
, 0);
2773 ret
= lookup_slow(&this, base
, 0);
2776 EXPORT_SYMBOL(lookup_one_unlocked
);
2779 * lookup_one_positive_unlocked - filesystem helper to lookup single
2780 * pathname component
2781 * @idmap: idmap of the mount the lookup is performed from
2782 * @name: pathname component to lookup
2783 * @base: base directory to lookup from
2784 * @len: maximum length @len should be interpreted to
2786 * This helper will yield ERR_PTR(-ENOENT) on negatives. The helper returns
2787 * known positive or ERR_PTR(). This is what most of the users want.
2789 * Note that pinned negative with unlocked parent _can_ become positive at any
2790 * time, so callers of lookup_one_unlocked() need to be very careful; pinned
2791 * positives have >d_inode stable, so this one avoids such problems.
2793 * Note that this routine is purely a helper for filesystem usage and should
2794 * not be called by generic code.
2796 * The helper should be called without i_mutex held.
2798 struct dentry
*lookup_one_positive_unlocked(struct mnt_idmap
*idmap
,
2800 struct dentry
*base
, int len
)
2802 struct dentry
*ret
= lookup_one_unlocked(idmap
, name
, base
, len
);
2804 if (!IS_ERR(ret
) && d_flags_negative(smp_load_acquire(&ret
->d_flags
))) {
2806 ret
= ERR_PTR(-ENOENT
);
2810 EXPORT_SYMBOL(lookup_one_positive_unlocked
);
2813 * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
2814 * @name: pathname component to lookup
2815 * @base: base directory to lookup from
2816 * @len: maximum length @len should be interpreted to
2818 * Note that this routine is purely a helper for filesystem usage and should
2819 * not be called by generic code.
2821 * Unlike lookup_one_len, it should be called without the parent
2822 * i_mutex held, and will take the i_mutex itself if necessary.
2824 struct dentry
*lookup_one_len_unlocked(const char *name
,
2825 struct dentry
*base
, int len
)
2827 return lookup_one_unlocked(&nop_mnt_idmap
, name
, base
, len
);
2829 EXPORT_SYMBOL(lookup_one_len_unlocked
);
2832 * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT)
2833 * on negatives. Returns known positive or ERR_PTR(); that's what
2834 * most of the users want. Note that pinned negative with unlocked parent
2835 * _can_ become positive at any time, so callers of lookup_one_len_unlocked()
2836 * need to be very careful; pinned positives have ->d_inode stable, so
2837 * this one avoids such problems.
2839 struct dentry
*lookup_positive_unlocked(const char *name
,
2840 struct dentry
*base
, int len
)
2842 return lookup_one_positive_unlocked(&nop_mnt_idmap
, name
, base
, len
);
2844 EXPORT_SYMBOL(lookup_positive_unlocked
);
2846 #ifdef CONFIG_UNIX98_PTYS
2847 int path_pts(struct path
*path
)
2849 /* Find something mounted on "pts" in the same directory as
2852 struct dentry
*parent
= dget_parent(path
->dentry
);
2853 struct dentry
*child
;
2854 struct qstr
this = QSTR_INIT("pts", 3);
2856 if (unlikely(!path_connected(path
->mnt
, parent
))) {
2861 path
->dentry
= parent
;
2862 child
= d_hash_and_lookup(parent
, &this);
2866 path
->dentry
= child
;
2868 follow_down(path
, 0);
2873 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
2874 struct path
*path
, int *empty
)
2876 struct filename
*filename
= getname_flags(name
, flags
, empty
);
2877 int ret
= filename_lookup(dfd
, filename
, flags
, path
, NULL
);
2882 EXPORT_SYMBOL(user_path_at_empty
);
2884 int __check_sticky(struct mnt_idmap
*idmap
, struct inode
*dir
,
2885 struct inode
*inode
)
2887 kuid_t fsuid
= current_fsuid();
2889 if (vfsuid_eq_kuid(i_uid_into_vfsuid(idmap
, inode
), fsuid
))
2891 if (vfsuid_eq_kuid(i_uid_into_vfsuid(idmap
, dir
), fsuid
))
2893 return !capable_wrt_inode_uidgid(idmap
, inode
, CAP_FOWNER
);
2895 EXPORT_SYMBOL(__check_sticky
);
2898 * Check whether we can remove a link victim from directory dir, check
2899 * whether the type of victim is right.
2900 * 1. We can't do it if dir is read-only (done in permission())
2901 * 2. We should have write and exec permissions on dir
2902 * 3. We can't remove anything from append-only dir
2903 * 4. We can't do anything with immutable dir (done in permission())
2904 * 5. If the sticky bit on dir is set we should either
2905 * a. be owner of dir, or
2906 * b. be owner of victim, or
2907 * c. have CAP_FOWNER capability
2908 * 6. If the victim is append-only or immutable we can't do antyhing with
2909 * links pointing to it.
2910 * 7. If the victim has an unknown uid or gid we can't change the inode.
2911 * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2912 * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2913 * 10. We can't remove a root or mountpoint.
2914 * 11. We don't allow removal of NFS sillyrenamed files; it's handled by
2915 * nfs_async_unlink().
2917 static int may_delete(struct mnt_idmap
*idmap
, struct inode
*dir
,
2918 struct dentry
*victim
, bool isdir
)
2920 struct inode
*inode
= d_backing_inode(victim
);
2923 if (d_is_negative(victim
))
2927 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
2929 /* Inode writeback is not safe when the uid or gid are invalid. */
2930 if (!vfsuid_valid(i_uid_into_vfsuid(idmap
, inode
)) ||
2931 !vfsgid_valid(i_gid_into_vfsgid(idmap
, inode
)))
2934 audit_inode_child(dir
, victim
, AUDIT_TYPE_CHILD_DELETE
);
2936 error
= inode_permission(idmap
, dir
, MAY_WRITE
| MAY_EXEC
);
2942 if (check_sticky(idmap
, dir
, inode
) || IS_APPEND(inode
) ||
2943 IS_IMMUTABLE(inode
) || IS_SWAPFILE(inode
) ||
2944 HAS_UNMAPPED_ID(idmap
, inode
))
2947 if (!d_is_dir(victim
))
2949 if (IS_ROOT(victim
))
2951 } else if (d_is_dir(victim
))
2953 if (IS_DEADDIR(dir
))
2955 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2960 /* Check whether we can create an object with dentry child in directory
2962 * 1. We can't do it if child already exists (open has special treatment for
2963 * this case, but since we are inlined it's OK)
2964 * 2. We can't do it if dir is read-only (done in permission())
2965 * 3. We can't do it if the fs can't represent the fsuid or fsgid.
2966 * 4. We should have write and exec permissions on dir
2967 * 5. We can't do it if dir is immutable (done in permission())
2969 static inline int may_create(struct mnt_idmap
*idmap
,
2970 struct inode
*dir
, struct dentry
*child
)
2972 audit_inode_child(dir
, child
, AUDIT_TYPE_CHILD_CREATE
);
2975 if (IS_DEADDIR(dir
))
2977 if (!fsuidgid_has_mapping(dir
->i_sb
, idmap
))
2980 return inode_permission(idmap
, dir
, MAY_WRITE
| MAY_EXEC
);
2984 * p1 and p2 should be directories on the same fs.
2986 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2991 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
2995 mutex_lock(&p1
->d_sb
->s_vfs_rename_mutex
);
2997 p
= d_ancestor(p2
, p1
);
2999 inode_lock_nested(p2
->d_inode
, I_MUTEX_PARENT
);
3000 inode_lock_nested(p1
->d_inode
, I_MUTEX_CHILD
);
3004 p
= d_ancestor(p1
, p2
);
3006 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
3007 inode_lock_nested(p2
->d_inode
, I_MUTEX_CHILD
);
3011 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
3012 inode_lock_nested(p2
->d_inode
, I_MUTEX_PARENT2
);
3015 EXPORT_SYMBOL(lock_rename
);
3017 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
3019 inode_unlock(p1
->d_inode
);
3021 inode_unlock(p2
->d_inode
);
3022 mutex_unlock(&p1
->d_sb
->s_vfs_rename_mutex
);
3025 EXPORT_SYMBOL(unlock_rename
);
3028 * mode_strip_umask - handle vfs umask stripping
3029 * @dir: parent directory of the new inode
3030 * @mode: mode of the new inode to be created in @dir
3032 * Umask stripping depends on whether or not the filesystem supports POSIX
3033 * ACLs. If the filesystem doesn't support it umask stripping is done directly
3034 * in here. If the filesystem does support POSIX ACLs umask stripping is
3035 * deferred until the filesystem calls posix_acl_create().
3039 static inline umode_t
mode_strip_umask(const struct inode
*dir
, umode_t mode
)
3041 if (!IS_POSIXACL(dir
))
3042 mode
&= ~current_umask();
3047 * vfs_prepare_mode - prepare the mode to be used for a new inode
3048 * @idmap: idmap of the mount the inode was found from
3049 * @dir: parent directory of the new inode
3050 * @mode: mode of the new inode
3051 * @mask_perms: allowed permission by the vfs
3052 * @type: type of file to be created
3054 * This helper consolidates and enforces vfs restrictions on the @mode of a new
3055 * object to be created.
3057 * Umask stripping depends on whether the filesystem supports POSIX ACLs (see
3058 * the kernel documentation for mode_strip_umask()). Moving umask stripping
3059 * after setgid stripping allows the same ordering for both non-POSIX ACL and
3060 * POSIX ACL supporting filesystems.
3062 * Note that it's currently valid for @type to be 0 if a directory is created.
3063 * Filesystems raise that flag individually and we need to check whether each
3064 * filesystem can deal with receiving S_IFDIR from the vfs before we enforce a
3067 * Returns: mode to be passed to the filesystem
3069 static inline umode_t
vfs_prepare_mode(struct mnt_idmap
*idmap
,
3070 const struct inode
*dir
, umode_t mode
,
3071 umode_t mask_perms
, umode_t type
)
3073 mode
= mode_strip_sgid(idmap
, dir
, mode
);
3074 mode
= mode_strip_umask(dir
, mode
);
3077 * Apply the vfs mandated allowed permission mask and set the type of
3078 * file to be created before we call into the filesystem.
3080 mode
&= (mask_perms
& ~S_IFMT
);
3081 mode
|= (type
& S_IFMT
);
3087 * vfs_create - create new file
3088 * @idmap: idmap of the mount the inode was found from
3089 * @dir: inode of @dentry
3090 * @dentry: pointer to dentry of the base directory
3091 * @mode: mode of the new file
3092 * @want_excl: whether the file must not yet exist
3094 * Create a new file.
3096 * If the inode has been found through an idmapped mount the idmap of
3097 * the vfsmount must be passed through @idmap. This function will then take
3098 * care to map the inode according to @idmap before checking permissions.
3099 * On non-idmapped mounts or if permission checking is to be performed on the
3100 * raw inode simply passs @nop_mnt_idmap.
3102 int vfs_create(struct mnt_idmap
*idmap
, struct inode
*dir
,
3103 struct dentry
*dentry
, umode_t mode
, bool want_excl
)
3107 error
= may_create(idmap
, dir
, dentry
);
3111 if (!dir
->i_op
->create
)
3112 return -EACCES
; /* shouldn't it be ENOSYS? */
3114 mode
= vfs_prepare_mode(idmap
, dir
, mode
, S_IALLUGO
, S_IFREG
);
3115 error
= security_inode_create(dir
, dentry
, mode
);
3118 error
= dir
->i_op
->create(idmap
, dir
, dentry
, mode
, want_excl
);
3120 fsnotify_create(dir
, dentry
);
3123 EXPORT_SYMBOL(vfs_create
);
3125 int vfs_mkobj(struct dentry
*dentry
, umode_t mode
,
3126 int (*f
)(struct dentry
*, umode_t
, void *),
3129 struct inode
*dir
= dentry
->d_parent
->d_inode
;
3130 int error
= may_create(&nop_mnt_idmap
, dir
, dentry
);
3136 error
= security_inode_create(dir
, dentry
, mode
);
3139 error
= f(dentry
, mode
, arg
);
3141 fsnotify_create(dir
, dentry
);
3144 EXPORT_SYMBOL(vfs_mkobj
);
3146 bool may_open_dev(const struct path
*path
)
3148 return !(path
->mnt
->mnt_flags
& MNT_NODEV
) &&
3149 !(path
->mnt
->mnt_sb
->s_iflags
& SB_I_NODEV
);
3152 static int may_open(struct mnt_idmap
*idmap
, const struct path
*path
,
3153 int acc_mode
, int flag
)
3155 struct dentry
*dentry
= path
->dentry
;
3156 struct inode
*inode
= dentry
->d_inode
;
3162 switch (inode
->i_mode
& S_IFMT
) {
3166 if (acc_mode
& MAY_WRITE
)
3168 if (acc_mode
& MAY_EXEC
)
3173 if (!may_open_dev(path
))
3178 if (acc_mode
& MAY_EXEC
)
3183 if ((acc_mode
& MAY_EXEC
) && path_noexec(path
))
3188 error
= inode_permission(idmap
, inode
, MAY_OPEN
| acc_mode
);
3193 * An append-only file must be opened in append mode for writing.
3195 if (IS_APPEND(inode
)) {
3196 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
3202 /* O_NOATIME can only be set by the owner or superuser */
3203 if (flag
& O_NOATIME
&& !inode_owner_or_capable(idmap
, inode
))
3209 static int handle_truncate(struct mnt_idmap
*idmap
, struct file
*filp
)
3211 const struct path
*path
= &filp
->f_path
;
3212 struct inode
*inode
= path
->dentry
->d_inode
;
3213 int error
= get_write_access(inode
);
3217 error
= security_file_truncate(filp
);
3219 error
= do_truncate(idmap
, path
->dentry
, 0,
3220 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
3223 put_write_access(inode
);
3227 static inline int open_to_namei_flags(int flag
)
3229 if ((flag
& O_ACCMODE
) == 3)
3234 static int may_o_create(struct mnt_idmap
*idmap
,
3235 const struct path
*dir
, struct dentry
*dentry
,
3238 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
3242 if (!fsuidgid_has_mapping(dir
->dentry
->d_sb
, idmap
))
3245 error
= inode_permission(idmap
, dir
->dentry
->d_inode
,
3246 MAY_WRITE
| MAY_EXEC
);
3250 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
3254 * Attempt to atomically look up, create and open a file from a negative
3257 * Returns 0 if successful. The file will have been created and attached to
3258 * @file by the filesystem calling finish_open().
3260 * If the file was looked up only or didn't need creating, FMODE_OPENED won't
3261 * be set. The caller will need to perform the open themselves. @path will
3262 * have been updated to point to the new dentry. This may be negative.
3264 * Returns an error code otherwise.
3266 static struct dentry
*atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
3268 int open_flag
, umode_t mode
)
3270 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
3271 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
3274 if (nd
->flags
& LOOKUP_DIRECTORY
)
3275 open_flag
|= O_DIRECTORY
;
3277 file
->f_path
.dentry
= DENTRY_NOT_SET
;
3278 file
->f_path
.mnt
= nd
->path
.mnt
;
3279 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
,
3280 open_to_namei_flags(open_flag
), mode
);
3281 d_lookup_done(dentry
);
3283 if (file
->f_mode
& FMODE_OPENED
) {
3284 if (unlikely(dentry
!= file
->f_path
.dentry
)) {
3286 dentry
= dget(file
->f_path
.dentry
);
3288 } else if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
3291 if (file
->f_path
.dentry
) {
3293 dentry
= file
->f_path
.dentry
;
3295 if (unlikely(d_is_negative(dentry
)))
3301 dentry
= ERR_PTR(error
);
3307 * Look up and maybe create and open the last component.
3309 * Must be called with parent locked (exclusive in O_CREAT case).
3311 * Returns 0 on success, that is, if
3312 * the file was successfully atomically created (if necessary) and opened, or
3313 * the file was not completely opened at this time, though lookups and
3314 * creations were performed.
3315 * These case are distinguished by presence of FMODE_OPENED on file->f_mode.
3316 * In the latter case dentry returned in @path might be negative if O_CREAT
3317 * hadn't been specified.
3319 * An error code is returned on failure.
3321 static struct dentry
*lookup_open(struct nameidata
*nd
, struct file
*file
,
3322 const struct open_flags
*op
,
3325 struct mnt_idmap
*idmap
;
3326 struct dentry
*dir
= nd
->path
.dentry
;
3327 struct inode
*dir_inode
= dir
->d_inode
;
3328 int open_flag
= op
->open_flag
;
3329 struct dentry
*dentry
;
3330 int error
, create_error
= 0;
3331 umode_t mode
= op
->mode
;
3332 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq
);
3334 if (unlikely(IS_DEADDIR(dir_inode
)))
3335 return ERR_PTR(-ENOENT
);
3337 file
->f_mode
&= ~FMODE_CREATED
;
3338 dentry
= d_lookup(dir
, &nd
->last
);
3341 dentry
= d_alloc_parallel(dir
, &nd
->last
, &wq
);
3345 if (d_in_lookup(dentry
))
3348 error
= d_revalidate(dentry
, nd
->flags
);
3349 if (likely(error
> 0))
3353 d_invalidate(dentry
);
3357 if (dentry
->d_inode
) {
3358 /* Cached positive dentry: will open in f_op->open */
3363 * Checking write permission is tricky, bacuse we don't know if we are
3364 * going to actually need it: O_CREAT opens should work as long as the
3365 * file exists. But checking existence breaks atomicity. The trick is
3366 * to check access and if not granted clear O_CREAT from the flags.
3368 * Another problem is returing the "right" error value (e.g. for an
3369 * O_EXCL open we want to return EEXIST not EROFS).
3371 if (unlikely(!got_write
))
3372 open_flag
&= ~O_TRUNC
;
3373 idmap
= mnt_idmap(nd
->path
.mnt
);
3374 if (open_flag
& O_CREAT
) {
3375 if (open_flag
& O_EXCL
)
3376 open_flag
&= ~O_TRUNC
;
3377 mode
= vfs_prepare_mode(idmap
, dir
->d_inode
, mode
, mode
, mode
);
3378 if (likely(got_write
))
3379 create_error
= may_o_create(idmap
, &nd
->path
,
3382 create_error
= -EROFS
;
3385 open_flag
&= ~O_CREAT
;
3386 if (dir_inode
->i_op
->atomic_open
) {
3387 dentry
= atomic_open(nd
, dentry
, file
, open_flag
, mode
);
3388 if (unlikely(create_error
) && dentry
== ERR_PTR(-ENOENT
))
3389 dentry
= ERR_PTR(create_error
);
3393 if (d_in_lookup(dentry
)) {
3394 struct dentry
*res
= dir_inode
->i_op
->lookup(dir_inode
, dentry
,
3396 d_lookup_done(dentry
);
3397 if (unlikely(res
)) {
3399 error
= PTR_ERR(res
);
3407 /* Negative dentry, just create the file */
3408 if (!dentry
->d_inode
&& (open_flag
& O_CREAT
)) {
3409 file
->f_mode
|= FMODE_CREATED
;
3410 audit_inode_child(dir_inode
, dentry
, AUDIT_TYPE_CHILD_CREATE
);
3411 if (!dir_inode
->i_op
->create
) {
3416 error
= dir_inode
->i_op
->create(idmap
, dir_inode
, dentry
,
3417 mode
, open_flag
& O_EXCL
);
3421 if (unlikely(create_error
) && !dentry
->d_inode
) {
3422 error
= create_error
;
3429 return ERR_PTR(error
);
3432 static const char *open_last_lookups(struct nameidata
*nd
,
3433 struct file
*file
, const struct open_flags
*op
)
3435 struct dentry
*dir
= nd
->path
.dentry
;
3436 int open_flag
= op
->open_flag
;
3437 bool got_write
= false;
3438 struct dentry
*dentry
;
3441 nd
->flags
|= op
->intent
;
3443 if (nd
->last_type
!= LAST_NORM
) {
3446 return handle_dots(nd
, nd
->last_type
);
3449 if (!(open_flag
& O_CREAT
)) {
3450 if (nd
->last
.name
[nd
->last
.len
])
3451 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
3452 /* we _can_ be in RCU mode here */
3453 dentry
= lookup_fast(nd
);
3455 return ERR_CAST(dentry
);
3459 BUG_ON(nd
->flags
& LOOKUP_RCU
);
3461 /* create side of things */
3462 if (nd
->flags
& LOOKUP_RCU
) {
3463 if (!try_to_unlazy(nd
))
3464 return ERR_PTR(-ECHILD
);
3466 audit_inode(nd
->name
, dir
, AUDIT_INODE_PARENT
);
3467 /* trailing slashes? */
3468 if (unlikely(nd
->last
.name
[nd
->last
.len
]))
3469 return ERR_PTR(-EISDIR
);
3472 if (open_flag
& (O_CREAT
| O_TRUNC
| O_WRONLY
| O_RDWR
)) {
3473 got_write
= !mnt_want_write(nd
->path
.mnt
);
3475 * do _not_ fail yet - we might not need that or fail with
3476 * a different error; let lookup_open() decide; we'll be
3477 * dropping this one anyway.
3480 if (open_flag
& O_CREAT
)
3481 inode_lock(dir
->d_inode
);
3483 inode_lock_shared(dir
->d_inode
);
3484 dentry
= lookup_open(nd
, file
, op
, got_write
);
3485 if (!IS_ERR(dentry
) && (file
->f_mode
& FMODE_CREATED
))
3486 fsnotify_create(dir
->d_inode
, dentry
);
3487 if (open_flag
& O_CREAT
)
3488 inode_unlock(dir
->d_inode
);
3490 inode_unlock_shared(dir
->d_inode
);
3493 mnt_drop_write(nd
->path
.mnt
);
3496 return ERR_CAST(dentry
);
3498 if (file
->f_mode
& (FMODE_OPENED
| FMODE_CREATED
)) {
3499 dput(nd
->path
.dentry
);
3500 nd
->path
.dentry
= dentry
;
3507 res
= step_into(nd
, WALK_TRAILING
, dentry
);
3509 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
3514 * Handle the last step of open()
3516 static int do_open(struct nameidata
*nd
,
3517 struct file
*file
, const struct open_flags
*op
)
3519 struct mnt_idmap
*idmap
;
3520 int open_flag
= op
->open_flag
;
3525 if (!(file
->f_mode
& (FMODE_OPENED
| FMODE_CREATED
))) {
3526 error
= complete_walk(nd
);
3530 if (!(file
->f_mode
& FMODE_CREATED
))
3531 audit_inode(nd
->name
, nd
->path
.dentry
, 0);
3532 idmap
= mnt_idmap(nd
->path
.mnt
);
3533 if (open_flag
& O_CREAT
) {
3534 if ((open_flag
& O_EXCL
) && !(file
->f_mode
& FMODE_CREATED
))
3536 if (d_is_dir(nd
->path
.dentry
))
3538 error
= may_create_in_sticky(idmap
, nd
,
3539 d_backing_inode(nd
->path
.dentry
));
3540 if (unlikely(error
))
3543 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !d_can_lookup(nd
->path
.dentry
))
3546 do_truncate
= false;
3547 acc_mode
= op
->acc_mode
;
3548 if (file
->f_mode
& FMODE_CREATED
) {
3549 /* Don't check for write permission, don't truncate */
3550 open_flag
&= ~O_TRUNC
;
3552 } else if (d_is_reg(nd
->path
.dentry
) && open_flag
& O_TRUNC
) {
3553 error
= mnt_want_write(nd
->path
.mnt
);
3558 error
= may_open(idmap
, &nd
->path
, acc_mode
, open_flag
);
3559 if (!error
&& !(file
->f_mode
& FMODE_OPENED
))
3560 error
= vfs_open(&nd
->path
, file
);
3562 error
= ima_file_check(file
, op
->acc_mode
);
3563 if (!error
&& do_truncate
)
3564 error
= handle_truncate(idmap
, file
);
3565 if (unlikely(error
> 0)) {
3570 mnt_drop_write(nd
->path
.mnt
);
3575 * vfs_tmpfile - create tmpfile
3576 * @idmap: idmap of the mount the inode was found from
3577 * @dentry: pointer to dentry of the base directory
3578 * @mode: mode of the new tmpfile
3581 * Create a temporary file.
3583 * If the inode has been found through an idmapped mount the idmap of
3584 * the vfsmount must be passed through @idmap. This function will then take
3585 * care to map the inode according to @idmap before checking permissions.
3586 * On non-idmapped mounts or if permission checking is to be performed on the
3587 * raw inode simply passs @nop_mnt_idmap.
3589 static int vfs_tmpfile(struct mnt_idmap
*idmap
,
3590 const struct path
*parentpath
,
3591 struct file
*file
, umode_t mode
)
3593 struct dentry
*child
;
3594 struct inode
*dir
= d_inode(parentpath
->dentry
);
3595 struct inode
*inode
;
3597 int open_flag
= file
->f_flags
;
3599 /* we want directory to be writable */
3600 error
= inode_permission(idmap
, dir
, MAY_WRITE
| MAY_EXEC
);
3603 if (!dir
->i_op
->tmpfile
)
3605 child
= d_alloc(parentpath
->dentry
, &slash_name
);
3606 if (unlikely(!child
))
3608 file
->f_path
.mnt
= parentpath
->mnt
;
3609 file
->f_path
.dentry
= child
;
3610 mode
= vfs_prepare_mode(idmap
, dir
, mode
, mode
, mode
);
3611 error
= dir
->i_op
->tmpfile(idmap
, dir
, file
, mode
);
3615 /* Don't check for other permissions, the inode was just created */
3616 error
= may_open(idmap
, &file
->f_path
, 0, file
->f_flags
);
3619 inode
= file_inode(file
);
3620 if (!(open_flag
& O_EXCL
)) {
3621 spin_lock(&inode
->i_lock
);
3622 inode
->i_state
|= I_LINKABLE
;
3623 spin_unlock(&inode
->i_lock
);
3625 ima_post_create_tmpfile(idmap
, inode
);
3630 * vfs_tmpfile_open - open a tmpfile for kernel internal use
3631 * @idmap: idmap of the mount the inode was found from
3632 * @parentpath: path of the base directory
3633 * @mode: mode of the new tmpfile
3635 * @cred: credentials for open
3637 * Create and open a temporary file. The file is not accounted in nr_files,
3638 * hence this is only for kernel internal use, and must not be installed into
3639 * file tables or such.
3641 struct file
*vfs_tmpfile_open(struct mnt_idmap
*idmap
,
3642 const struct path
*parentpath
,
3643 umode_t mode
, int open_flag
, const struct cred
*cred
)
3648 file
= alloc_empty_file_noaccount(open_flag
, cred
);
3649 if (!IS_ERR(file
)) {
3650 error
= vfs_tmpfile(idmap
, parentpath
, file
, mode
);
3653 file
= ERR_PTR(error
);
3658 EXPORT_SYMBOL(vfs_tmpfile_open
);
3660 static int do_tmpfile(struct nameidata
*nd
, unsigned flags
,
3661 const struct open_flags
*op
,
3665 int error
= path_lookupat(nd
, flags
| LOOKUP_DIRECTORY
, &path
);
3667 if (unlikely(error
))
3669 error
= mnt_want_write(path
.mnt
);
3670 if (unlikely(error
))
3672 error
= vfs_tmpfile(mnt_idmap(path
.mnt
), &path
, file
, op
->mode
);
3675 audit_inode(nd
->name
, file
->f_path
.dentry
, 0);
3677 mnt_drop_write(path
.mnt
);
3683 static int do_o_path(struct nameidata
*nd
, unsigned flags
, struct file
*file
)
3686 int error
= path_lookupat(nd
, flags
, &path
);
3688 audit_inode(nd
->name
, path
.dentry
, 0);
3689 error
= vfs_open(&path
, file
);
3695 static struct file
*path_openat(struct nameidata
*nd
,
3696 const struct open_flags
*op
, unsigned flags
)
3701 file
= alloc_empty_file(op
->open_flag
, current_cred());
3705 if (unlikely(file
->f_flags
& __O_TMPFILE
)) {
3706 error
= do_tmpfile(nd
, flags
, op
, file
);
3707 } else if (unlikely(file
->f_flags
& O_PATH
)) {
3708 error
= do_o_path(nd
, flags
, file
);
3710 const char *s
= path_init(nd
, flags
);
3711 while (!(error
= link_path_walk(s
, nd
)) &&
3712 (s
= open_last_lookups(nd
, file
, op
)) != NULL
)
3715 error
= do_open(nd
, file
, op
);
3718 if (likely(!error
)) {
3719 if (likely(file
->f_mode
& FMODE_OPENED
))
3725 if (error
== -EOPENSTALE
) {
3726 if (flags
& LOOKUP_RCU
)
3731 return ERR_PTR(error
);
3734 struct file
*do_filp_open(int dfd
, struct filename
*pathname
,
3735 const struct open_flags
*op
)
3737 struct nameidata nd
;
3738 int flags
= op
->lookup_flags
;
3741 set_nameidata(&nd
, dfd
, pathname
, NULL
);
3742 filp
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3743 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
3744 filp
= path_openat(&nd
, op
, flags
);
3745 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
3746 filp
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3747 restore_nameidata();
3751 struct file
*do_file_open_root(const struct path
*root
,
3752 const char *name
, const struct open_flags
*op
)
3754 struct nameidata nd
;
3756 struct filename
*filename
;
3757 int flags
= op
->lookup_flags
;
3759 if (d_is_symlink(root
->dentry
) && op
->intent
& LOOKUP_OPEN
)
3760 return ERR_PTR(-ELOOP
);
3762 filename
= getname_kernel(name
);
3763 if (IS_ERR(filename
))
3764 return ERR_CAST(filename
);
3766 set_nameidata(&nd
, -1, filename
, root
);
3767 file
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3768 if (unlikely(file
== ERR_PTR(-ECHILD
)))
3769 file
= path_openat(&nd
, op
, flags
);
3770 if (unlikely(file
== ERR_PTR(-ESTALE
)))
3771 file
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3772 restore_nameidata();
3777 static struct dentry
*filename_create(int dfd
, struct filename
*name
,
3778 struct path
*path
, unsigned int lookup_flags
)
3780 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
3782 bool want_dir
= lookup_flags
& LOOKUP_DIRECTORY
;
3783 unsigned int reval_flag
= lookup_flags
& LOOKUP_REVAL
;
3784 unsigned int create_flags
= LOOKUP_CREATE
| LOOKUP_EXCL
;
3789 error
= filename_parentat(dfd
, name
, reval_flag
, path
, &last
, &type
);
3791 return ERR_PTR(error
);
3794 * Yucky last component or no last component at all?
3795 * (foo/., foo/.., /////)
3797 if (unlikely(type
!= LAST_NORM
))
3800 /* don't fail immediately if it's r/o, at least try to report other errors */
3801 err2
= mnt_want_write(path
->mnt
);
3803 * Do the final lookup. Suppress 'create' if there is a trailing
3804 * '/', and a directory wasn't requested.
3806 if (last
.name
[last
.len
] && !want_dir
)
3808 inode_lock_nested(path
->dentry
->d_inode
, I_MUTEX_PARENT
);
3809 dentry
= __lookup_hash(&last
, path
->dentry
, reval_flag
| create_flags
);
3814 if (d_is_positive(dentry
))
3818 * Special case - lookup gave negative, but... we had foo/bar/
3819 * From the vfs_mknod() POV we just have a negative dentry -
3820 * all is fine. Let's be bastards - you had / on the end, you've
3821 * been asking for (non-existent) directory. -ENOENT for you.
3823 if (unlikely(!create_flags
)) {
3827 if (unlikely(err2
)) {
3834 dentry
= ERR_PTR(error
);
3836 inode_unlock(path
->dentry
->d_inode
);
3838 mnt_drop_write(path
->mnt
);
3844 struct dentry
*kern_path_create(int dfd
, const char *pathname
,
3845 struct path
*path
, unsigned int lookup_flags
)
3847 struct filename
*filename
= getname_kernel(pathname
);
3848 struct dentry
*res
= filename_create(dfd
, filename
, path
, lookup_flags
);
3853 EXPORT_SYMBOL(kern_path_create
);
3855 void done_path_create(struct path
*path
, struct dentry
*dentry
)
3858 inode_unlock(path
->dentry
->d_inode
);
3859 mnt_drop_write(path
->mnt
);
3862 EXPORT_SYMBOL(done_path_create
);
3864 inline struct dentry
*user_path_create(int dfd
, const char __user
*pathname
,
3865 struct path
*path
, unsigned int lookup_flags
)
3867 struct filename
*filename
= getname(pathname
);
3868 struct dentry
*res
= filename_create(dfd
, filename
, path
, lookup_flags
);
3873 EXPORT_SYMBOL(user_path_create
);
3876 * vfs_mknod - create device node or file
3877 * @idmap: idmap of the mount the inode was found from
3878 * @dir: inode of @dentry
3879 * @dentry: pointer to dentry of the base directory
3880 * @mode: mode of the new device node or file
3881 * @dev: device number of device to create
3883 * Create a device node or file.
3885 * If the inode has been found through an idmapped mount the idmap of
3886 * the vfsmount must be passed through @idmap. This function will then take
3887 * care to map the inode according to @idmap before checking permissions.
3888 * On non-idmapped mounts or if permission checking is to be performed on the
3889 * raw inode simply passs @nop_mnt_idmap.
3891 int vfs_mknod(struct mnt_idmap
*idmap
, struct inode
*dir
,
3892 struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3894 bool is_whiteout
= S_ISCHR(mode
) && dev
== WHITEOUT_DEV
;
3895 int error
= may_create(idmap
, dir
, dentry
);
3900 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !is_whiteout
&&
3901 !capable(CAP_MKNOD
))
3904 if (!dir
->i_op
->mknod
)
3907 mode
= vfs_prepare_mode(idmap
, dir
, mode
, mode
, mode
);
3908 error
= devcgroup_inode_mknod(mode
, dev
);
3912 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
3916 error
= dir
->i_op
->mknod(idmap
, dir
, dentry
, mode
, dev
);
3918 fsnotify_create(dir
, dentry
);
3921 EXPORT_SYMBOL(vfs_mknod
);
3923 static int may_mknod(umode_t mode
)
3925 switch (mode
& S_IFMT
) {
3931 case 0: /* zero mode translates to S_IFREG */
3940 static int do_mknodat(int dfd
, struct filename
*name
, umode_t mode
,
3943 struct mnt_idmap
*idmap
;
3944 struct dentry
*dentry
;
3947 unsigned int lookup_flags
= 0;
3949 error
= may_mknod(mode
);
3953 dentry
= filename_create(dfd
, name
, &path
, lookup_flags
);
3954 error
= PTR_ERR(dentry
);
3958 error
= security_path_mknod(&path
, dentry
,
3959 mode_strip_umask(path
.dentry
->d_inode
, mode
), dev
);
3963 idmap
= mnt_idmap(path
.mnt
);
3964 switch (mode
& S_IFMT
) {
3965 case 0: case S_IFREG
:
3966 error
= vfs_create(idmap
, path
.dentry
->d_inode
,
3967 dentry
, mode
, true);
3969 ima_post_path_mknod(idmap
, dentry
);
3971 case S_IFCHR
: case S_IFBLK
:
3972 error
= vfs_mknod(idmap
, path
.dentry
->d_inode
,
3973 dentry
, mode
, new_decode_dev(dev
));
3975 case S_IFIFO
: case S_IFSOCK
:
3976 error
= vfs_mknod(idmap
, path
.dentry
->d_inode
,
3981 done_path_create(&path
, dentry
);
3982 if (retry_estale(error
, lookup_flags
)) {
3983 lookup_flags
|= LOOKUP_REVAL
;
3991 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
3994 return do_mknodat(dfd
, getname(filename
), mode
, dev
);
3997 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
3999 return do_mknodat(AT_FDCWD
, getname(filename
), mode
, dev
);
4003 * vfs_mkdir - create directory
4004 * @idmap: idmap of the mount the inode was found from
4005 * @dir: inode of @dentry
4006 * @dentry: pointer to dentry of the base directory
4007 * @mode: mode of the new directory
4009 * Create a directory.
4011 * If the inode has been found through an idmapped mount the idmap of
4012 * the vfsmount must be passed through @idmap. This function will then take
4013 * care to map the inode according to @idmap before checking permissions.
4014 * On non-idmapped mounts or if permission checking is to be performed on the
4015 * raw inode simply passs @nop_mnt_idmap.
4017 int vfs_mkdir(struct mnt_idmap
*idmap
, struct inode
*dir
,
4018 struct dentry
*dentry
, umode_t mode
)
4021 unsigned max_links
= dir
->i_sb
->s_max_links
;
4023 error
= may_create(idmap
, dir
, dentry
);
4027 if (!dir
->i_op
->mkdir
)
4030 mode
= vfs_prepare_mode(idmap
, dir
, mode
, S_IRWXUGO
| S_ISVTX
, 0);
4031 error
= security_inode_mkdir(dir
, dentry
, mode
);
4035 if (max_links
&& dir
->i_nlink
>= max_links
)
4038 error
= dir
->i_op
->mkdir(idmap
, dir
, dentry
, mode
);
4040 fsnotify_mkdir(dir
, dentry
);
4043 EXPORT_SYMBOL(vfs_mkdir
);
4045 int do_mkdirat(int dfd
, struct filename
*name
, umode_t mode
)
4047 struct dentry
*dentry
;
4050 unsigned int lookup_flags
= LOOKUP_DIRECTORY
;
4053 dentry
= filename_create(dfd
, name
, &path
, lookup_flags
);
4054 error
= PTR_ERR(dentry
);
4058 error
= security_path_mkdir(&path
, dentry
,
4059 mode_strip_umask(path
.dentry
->d_inode
, mode
));
4061 error
= vfs_mkdir(mnt_idmap(path
.mnt
), path
.dentry
->d_inode
,
4064 done_path_create(&path
, dentry
);
4065 if (retry_estale(error
, lookup_flags
)) {
4066 lookup_flags
|= LOOKUP_REVAL
;
4074 SYSCALL_DEFINE3(mkdirat
, int, dfd
, const char __user
*, pathname
, umode_t
, mode
)
4076 return do_mkdirat(dfd
, getname(pathname
), mode
);
4079 SYSCALL_DEFINE2(mkdir
, const char __user
*, pathname
, umode_t
, mode
)
4081 return do_mkdirat(AT_FDCWD
, getname(pathname
), mode
);
4085 * vfs_rmdir - remove directory
4086 * @idmap: idmap of the mount the inode was found from
4087 * @dir: inode of @dentry
4088 * @dentry: pointer to dentry of the base directory
4090 * Remove a directory.
4092 * If the inode has been found through an idmapped mount the idmap of
4093 * the vfsmount must be passed through @idmap. This function will then take
4094 * care to map the inode according to @idmap before checking permissions.
4095 * On non-idmapped mounts or if permission checking is to be performed on the
4096 * raw inode simply passs @nop_mnt_idmap.
4098 int vfs_rmdir(struct mnt_idmap
*idmap
, struct inode
*dir
,
4099 struct dentry
*dentry
)
4101 int error
= may_delete(idmap
, dir
, dentry
, 1);
4106 if (!dir
->i_op
->rmdir
)
4110 inode_lock(dentry
->d_inode
);
4113 if (is_local_mountpoint(dentry
) ||
4114 (dentry
->d_inode
->i_flags
& S_KERNEL_FILE
))
4117 error
= security_inode_rmdir(dir
, dentry
);
4121 error
= dir
->i_op
->rmdir(dir
, dentry
);
4125 shrink_dcache_parent(dentry
);
4126 dentry
->d_inode
->i_flags
|= S_DEAD
;
4128 detach_mounts(dentry
);
4131 inode_unlock(dentry
->d_inode
);
4134 d_delete_notify(dir
, dentry
);
4137 EXPORT_SYMBOL(vfs_rmdir
);
4139 int do_rmdir(int dfd
, struct filename
*name
)
4142 struct dentry
*dentry
;
4146 unsigned int lookup_flags
= 0;
4148 error
= filename_parentat(dfd
, name
, lookup_flags
, &path
, &last
, &type
);
4164 error
= mnt_want_write(path
.mnt
);
4168 inode_lock_nested(path
.dentry
->d_inode
, I_MUTEX_PARENT
);
4169 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
4170 error
= PTR_ERR(dentry
);
4173 if (!dentry
->d_inode
) {
4177 error
= security_path_rmdir(&path
, dentry
);
4180 error
= vfs_rmdir(mnt_idmap(path
.mnt
), path
.dentry
->d_inode
, dentry
);
4184 inode_unlock(path
.dentry
->d_inode
);
4185 mnt_drop_write(path
.mnt
);
4188 if (retry_estale(error
, lookup_flags
)) {
4189 lookup_flags
|= LOOKUP_REVAL
;
4197 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
4199 return do_rmdir(AT_FDCWD
, getname(pathname
));
4203 * vfs_unlink - unlink a filesystem object
4204 * @idmap: idmap of the mount the inode was found from
4205 * @dir: parent directory
4207 * @delegated_inode: returns victim inode, if the inode is delegated.
4209 * The caller must hold dir->i_mutex.
4211 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
4212 * return a reference to the inode in delegated_inode. The caller
4213 * should then break the delegation on that inode and retry. Because
4214 * breaking a delegation may take a long time, the caller should drop
4215 * dir->i_mutex before doing so.
4217 * Alternatively, a caller may pass NULL for delegated_inode. This may
4218 * be appropriate for callers that expect the underlying filesystem not
4219 * to be NFS exported.
4221 * If the inode has been found through an idmapped mount the idmap of
4222 * the vfsmount must be passed through @idmap. This function will then take
4223 * care to map the inode according to @idmap before checking permissions.
4224 * On non-idmapped mounts or if permission checking is to be performed on the
4225 * raw inode simply passs @nop_mnt_idmap.
4227 int vfs_unlink(struct mnt_idmap
*idmap
, struct inode
*dir
,
4228 struct dentry
*dentry
, struct inode
**delegated_inode
)
4230 struct inode
*target
= dentry
->d_inode
;
4231 int error
= may_delete(idmap
, dir
, dentry
, 0);
4236 if (!dir
->i_op
->unlink
)
4240 if (IS_SWAPFILE(target
))
4242 else if (is_local_mountpoint(dentry
))
4245 error
= security_inode_unlink(dir
, dentry
);
4247 error
= try_break_deleg(target
, delegated_inode
);
4250 error
= dir
->i_op
->unlink(dir
, dentry
);
4253 detach_mounts(dentry
);
4258 inode_unlock(target
);
4260 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
4261 if (!error
&& dentry
->d_flags
& DCACHE_NFSFS_RENAMED
) {
4262 fsnotify_unlink(dir
, dentry
);
4263 } else if (!error
) {
4264 fsnotify_link_count(target
);
4265 d_delete_notify(dir
, dentry
);
4270 EXPORT_SYMBOL(vfs_unlink
);
4273 * Make sure that the actual truncation of the file will occur outside its
4274 * directory's i_mutex. Truncate can take a long time if there is a lot of
4275 * writeout happening, and we don't want to prevent access to the directory
4276 * while waiting on the I/O.
4278 int do_unlinkat(int dfd
, struct filename
*name
)
4281 struct dentry
*dentry
;
4285 struct inode
*inode
= NULL
;
4286 struct inode
*delegated_inode
= NULL
;
4287 unsigned int lookup_flags
= 0;
4289 error
= filename_parentat(dfd
, name
, lookup_flags
, &path
, &last
, &type
);
4294 if (type
!= LAST_NORM
)
4297 error
= mnt_want_write(path
.mnt
);
4301 inode_lock_nested(path
.dentry
->d_inode
, I_MUTEX_PARENT
);
4302 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
4303 error
= PTR_ERR(dentry
);
4304 if (!IS_ERR(dentry
)) {
4306 /* Why not before? Because we want correct error value */
4307 if (last
.name
[last
.len
])
4309 inode
= dentry
->d_inode
;
4310 if (d_is_negative(dentry
))
4313 error
= security_path_unlink(&path
, dentry
);
4316 error
= vfs_unlink(mnt_idmap(path
.mnt
), path
.dentry
->d_inode
,
4317 dentry
, &delegated_inode
);
4321 inode_unlock(path
.dentry
->d_inode
);
4323 iput(inode
); /* truncate the inode here */
4325 if (delegated_inode
) {
4326 error
= break_deleg_wait(&delegated_inode
);
4330 mnt_drop_write(path
.mnt
);
4333 if (retry_estale(error
, lookup_flags
)) {
4334 lookup_flags
|= LOOKUP_REVAL
;
4343 if (d_is_negative(dentry
))
4345 else if (d_is_dir(dentry
))
4352 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
4354 if ((flag
& ~AT_REMOVEDIR
) != 0)
4357 if (flag
& AT_REMOVEDIR
)
4358 return do_rmdir(dfd
, getname(pathname
));
4359 return do_unlinkat(dfd
, getname(pathname
));
4362 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
4364 return do_unlinkat(AT_FDCWD
, getname(pathname
));
4368 * vfs_symlink - create symlink
4369 * @idmap: idmap of the mount the inode was found from
4370 * @dir: inode of @dentry
4371 * @dentry: pointer to dentry of the base directory
4372 * @oldname: name of the file to link to
4376 * If the inode has been found through an idmapped mount the idmap of
4377 * the vfsmount must be passed through @idmap. This function will then take
4378 * care to map the inode according to @idmap before checking permissions.
4379 * On non-idmapped mounts or if permission checking is to be performed on the
4380 * raw inode simply passs @nop_mnt_idmap.
4382 int vfs_symlink(struct mnt_idmap
*idmap
, struct inode
*dir
,
4383 struct dentry
*dentry
, const char *oldname
)
4387 error
= may_create(idmap
, dir
, dentry
);
4391 if (!dir
->i_op
->symlink
)
4394 error
= security_inode_symlink(dir
, dentry
, oldname
);
4398 error
= dir
->i_op
->symlink(idmap
, dir
, dentry
, oldname
);
4400 fsnotify_create(dir
, dentry
);
4403 EXPORT_SYMBOL(vfs_symlink
);
4405 int do_symlinkat(struct filename
*from
, int newdfd
, struct filename
*to
)
4408 struct dentry
*dentry
;
4410 unsigned int lookup_flags
= 0;
4413 error
= PTR_ERR(from
);
4417 dentry
= filename_create(newdfd
, to
, &path
, lookup_flags
);
4418 error
= PTR_ERR(dentry
);
4422 error
= security_path_symlink(&path
, dentry
, from
->name
);
4424 error
= vfs_symlink(mnt_idmap(path
.mnt
), path
.dentry
->d_inode
,
4425 dentry
, from
->name
);
4426 done_path_create(&path
, dentry
);
4427 if (retry_estale(error
, lookup_flags
)) {
4428 lookup_flags
|= LOOKUP_REVAL
;
4437 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
4438 int, newdfd
, const char __user
*, newname
)
4440 return do_symlinkat(getname(oldname
), newdfd
, getname(newname
));
4443 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
4445 return do_symlinkat(getname(oldname
), AT_FDCWD
, getname(newname
));
4449 * vfs_link - create a new link
4450 * @old_dentry: object to be linked
4451 * @idmap: idmap of the mount
4453 * @new_dentry: where to create the new link
4454 * @delegated_inode: returns inode needing a delegation break
4456 * The caller must hold dir->i_mutex
4458 * If vfs_link discovers a delegation on the to-be-linked file in need
4459 * of breaking, it will return -EWOULDBLOCK and return a reference to the
4460 * inode in delegated_inode. The caller should then break the delegation
4461 * and retry. Because breaking a delegation may take a long time, the
4462 * caller should drop the i_mutex before doing so.
4464 * Alternatively, a caller may pass NULL for delegated_inode. This may
4465 * be appropriate for callers that expect the underlying filesystem not
4466 * to be NFS exported.
4468 * If the inode has been found through an idmapped mount the idmap of
4469 * the vfsmount must be passed through @idmap. This function will then take
4470 * care to map the inode according to @idmap before checking permissions.
4471 * On non-idmapped mounts or if permission checking is to be performed on the
4472 * raw inode simply passs @nop_mnt_idmap.
4474 int vfs_link(struct dentry
*old_dentry
, struct mnt_idmap
*idmap
,
4475 struct inode
*dir
, struct dentry
*new_dentry
,
4476 struct inode
**delegated_inode
)
4478 struct inode
*inode
= old_dentry
->d_inode
;
4479 unsigned max_links
= dir
->i_sb
->s_max_links
;
4485 error
= may_create(idmap
, dir
, new_dentry
);
4489 if (dir
->i_sb
!= inode
->i_sb
)
4493 * A link to an append-only or immutable file cannot be created.
4495 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
4498 * Updating the link count will likely cause i_uid and i_gid to
4499 * be writen back improperly if their true value is unknown to
4502 if (HAS_UNMAPPED_ID(idmap
, inode
))
4504 if (!dir
->i_op
->link
)
4506 if (S_ISDIR(inode
->i_mode
))
4509 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
4514 /* Make sure we don't allow creating hardlink to an unlinked file */
4515 if (inode
->i_nlink
== 0 && !(inode
->i_state
& I_LINKABLE
))
4517 else if (max_links
&& inode
->i_nlink
>= max_links
)
4520 error
= try_break_deleg(inode
, delegated_inode
);
4522 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
4525 if (!error
&& (inode
->i_state
& I_LINKABLE
)) {
4526 spin_lock(&inode
->i_lock
);
4527 inode
->i_state
&= ~I_LINKABLE
;
4528 spin_unlock(&inode
->i_lock
);
4530 inode_unlock(inode
);
4532 fsnotify_link(dir
, inode
, new_dentry
);
4535 EXPORT_SYMBOL(vfs_link
);
4538 * Hardlinks are often used in delicate situations. We avoid
4539 * security-related surprises by not following symlinks on the
4542 * We don't follow them on the oldname either to be compatible
4543 * with linux 2.0, and to avoid hard-linking to directories
4544 * and other special files. --ADM
4546 int do_linkat(int olddfd
, struct filename
*old
, int newdfd
,
4547 struct filename
*new, int flags
)
4549 struct mnt_idmap
*idmap
;
4550 struct dentry
*new_dentry
;
4551 struct path old_path
, new_path
;
4552 struct inode
*delegated_inode
= NULL
;
4556 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0) {
4561 * To use null names we require CAP_DAC_READ_SEARCH
4562 * This ensures that not everyone will be able to create
4563 * handlink using the passed filedescriptor.
4565 if (flags
& AT_EMPTY_PATH
&& !capable(CAP_DAC_READ_SEARCH
)) {
4570 if (flags
& AT_SYMLINK_FOLLOW
)
4571 how
|= LOOKUP_FOLLOW
;
4573 error
= filename_lookup(olddfd
, old
, how
, &old_path
, NULL
);
4577 new_dentry
= filename_create(newdfd
, new, &new_path
,
4578 (how
& LOOKUP_REVAL
));
4579 error
= PTR_ERR(new_dentry
);
4580 if (IS_ERR(new_dentry
))
4584 if (old_path
.mnt
!= new_path
.mnt
)
4586 idmap
= mnt_idmap(new_path
.mnt
);
4587 error
= may_linkat(idmap
, &old_path
);
4588 if (unlikely(error
))
4590 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
4593 error
= vfs_link(old_path
.dentry
, idmap
, new_path
.dentry
->d_inode
,
4594 new_dentry
, &delegated_inode
);
4596 done_path_create(&new_path
, new_dentry
);
4597 if (delegated_inode
) {
4598 error
= break_deleg_wait(&delegated_inode
);
4600 path_put(&old_path
);
4604 if (retry_estale(error
, how
)) {
4605 path_put(&old_path
);
4606 how
|= LOOKUP_REVAL
;
4610 path_put(&old_path
);
4618 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
4619 int, newdfd
, const char __user
*, newname
, int, flags
)
4621 return do_linkat(olddfd
, getname_uflags(oldname
, flags
),
4622 newdfd
, getname(newname
), flags
);
4625 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
4627 return do_linkat(AT_FDCWD
, getname(oldname
), AT_FDCWD
, getname(newname
), 0);
4631 * vfs_rename - rename a filesystem object
4632 * @rd: pointer to &struct renamedata info
4634 * The caller must hold multiple mutexes--see lock_rename()).
4636 * If vfs_rename discovers a delegation in need of breaking at either
4637 * the source or destination, it will return -EWOULDBLOCK and return a
4638 * reference to the inode in delegated_inode. The caller should then
4639 * break the delegation and retry. Because breaking a delegation may
4640 * take a long time, the caller should drop all locks before doing
4643 * Alternatively, a caller may pass NULL for delegated_inode. This may
4644 * be appropriate for callers that expect the underlying filesystem not
4645 * to be NFS exported.
4647 * The worst of all namespace operations - renaming directory. "Perverted"
4648 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4651 * a) we can get into loop creation.
4652 * b) race potential - two innocent renames can create a loop together.
4653 * That's where 4.4 screws up. Current fix: serialization on
4654 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
4656 * c) we have to lock _four_ objects - parents and victim (if it exists),
4657 * and source (if it is not a directory).
4658 * And that - after we got ->i_mutex on parents (until then we don't know
4659 * whether the target exists). Solution: try to be smart with locking
4660 * order for inodes. We rely on the fact that tree topology may change
4661 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
4662 * move will be locked. Thus we can rank directories by the tree
4663 * (ancestors first) and rank all non-directories after them.
4664 * That works since everybody except rename does "lock parent, lookup,
4665 * lock child" and rename is under ->s_vfs_rename_mutex.
4666 * HOWEVER, it relies on the assumption that any object with ->lookup()
4667 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4668 * we'd better make sure that there's no link(2) for them.
4669 * d) conversion from fhandle to dentry may come in the wrong moment - when
4670 * we are removing the target. Solution: we will have to grab ->i_mutex
4671 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
4672 * ->i_mutex on parents, which works but leads to some truly excessive
4675 int vfs_rename(struct renamedata
*rd
)
4678 struct inode
*old_dir
= rd
->old_dir
, *new_dir
= rd
->new_dir
;
4679 struct dentry
*old_dentry
= rd
->old_dentry
;
4680 struct dentry
*new_dentry
= rd
->new_dentry
;
4681 struct inode
**delegated_inode
= rd
->delegated_inode
;
4682 unsigned int flags
= rd
->flags
;
4683 bool is_dir
= d_is_dir(old_dentry
);
4684 struct inode
*source
= old_dentry
->d_inode
;
4685 struct inode
*target
= new_dentry
->d_inode
;
4686 bool new_is_dir
= false;
4687 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
4688 struct name_snapshot old_name
;
4690 if (source
== target
)
4693 error
= may_delete(rd
->old_mnt_idmap
, old_dir
, old_dentry
, is_dir
);
4698 error
= may_create(rd
->new_mnt_idmap
, new_dir
, new_dentry
);
4700 new_is_dir
= d_is_dir(new_dentry
);
4702 if (!(flags
& RENAME_EXCHANGE
))
4703 error
= may_delete(rd
->new_mnt_idmap
, new_dir
,
4704 new_dentry
, is_dir
);
4706 error
= may_delete(rd
->new_mnt_idmap
, new_dir
,
4707 new_dentry
, new_is_dir
);
4712 if (!old_dir
->i_op
->rename
)
4716 * If we are going to change the parent - check write permissions,
4717 * we'll need to flip '..'.
4719 if (new_dir
!= old_dir
) {
4721 error
= inode_permission(rd
->old_mnt_idmap
, source
,
4726 if ((flags
& RENAME_EXCHANGE
) && new_is_dir
) {
4727 error
= inode_permission(rd
->new_mnt_idmap
, target
,
4734 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
,
4739 take_dentry_name_snapshot(&old_name
, old_dentry
);
4741 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4742 lock_two_nondirectories(source
, target
);
4747 if (IS_SWAPFILE(source
) || (target
&& IS_SWAPFILE(target
)))
4751 if (is_local_mountpoint(old_dentry
) || is_local_mountpoint(new_dentry
))
4754 if (max_links
&& new_dir
!= old_dir
) {
4756 if (is_dir
&& !new_is_dir
&& new_dir
->i_nlink
>= max_links
)
4758 if ((flags
& RENAME_EXCHANGE
) && !is_dir
&& new_is_dir
&&
4759 old_dir
->i_nlink
>= max_links
)
4763 error
= try_break_deleg(source
, delegated_inode
);
4767 if (target
&& !new_is_dir
) {
4768 error
= try_break_deleg(target
, delegated_inode
);
4772 error
= old_dir
->i_op
->rename(rd
->new_mnt_idmap
, old_dir
, old_dentry
,
4773 new_dir
, new_dentry
, flags
);
4777 if (!(flags
& RENAME_EXCHANGE
) && target
) {
4779 shrink_dcache_parent(new_dentry
);
4780 target
->i_flags
|= S_DEAD
;
4782 dont_mount(new_dentry
);
4783 detach_mounts(new_dentry
);
4785 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
)) {
4786 if (!(flags
& RENAME_EXCHANGE
))
4787 d_move(old_dentry
, new_dentry
);
4789 d_exchange(old_dentry
, new_dentry
);
4792 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4793 unlock_two_nondirectories(source
, target
);
4795 inode_unlock(target
);
4798 fsnotify_move(old_dir
, new_dir
, &old_name
.name
, is_dir
,
4799 !(flags
& RENAME_EXCHANGE
) ? target
: NULL
, old_dentry
);
4800 if (flags
& RENAME_EXCHANGE
) {
4801 fsnotify_move(new_dir
, old_dir
, &old_dentry
->d_name
,
4802 new_is_dir
, NULL
, new_dentry
);
4805 release_dentry_name_snapshot(&old_name
);
4809 EXPORT_SYMBOL(vfs_rename
);
4811 int do_renameat2(int olddfd
, struct filename
*from
, int newdfd
,
4812 struct filename
*to
, unsigned int flags
)
4814 struct renamedata rd
;
4815 struct dentry
*old_dentry
, *new_dentry
;
4816 struct dentry
*trap
;
4817 struct path old_path
, new_path
;
4818 struct qstr old_last
, new_last
;
4819 int old_type
, new_type
;
4820 struct inode
*delegated_inode
= NULL
;
4821 unsigned int lookup_flags
= 0, target_flags
= LOOKUP_RENAME_TARGET
;
4822 bool should_retry
= false;
4823 int error
= -EINVAL
;
4825 if (flags
& ~(RENAME_NOREPLACE
| RENAME_EXCHANGE
| RENAME_WHITEOUT
))
4828 if ((flags
& (RENAME_NOREPLACE
| RENAME_WHITEOUT
)) &&
4829 (flags
& RENAME_EXCHANGE
))
4832 if (flags
& RENAME_EXCHANGE
)
4836 error
= filename_parentat(olddfd
, from
, lookup_flags
, &old_path
,
4837 &old_last
, &old_type
);
4841 error
= filename_parentat(newdfd
, to
, lookup_flags
, &new_path
, &new_last
,
4847 if (old_path
.mnt
!= new_path
.mnt
)
4851 if (old_type
!= LAST_NORM
)
4854 if (flags
& RENAME_NOREPLACE
)
4856 if (new_type
!= LAST_NORM
)
4859 error
= mnt_want_write(old_path
.mnt
);
4864 trap
= lock_rename(new_path
.dentry
, old_path
.dentry
);
4866 old_dentry
= __lookup_hash(&old_last
, old_path
.dentry
, lookup_flags
);
4867 error
= PTR_ERR(old_dentry
);
4868 if (IS_ERR(old_dentry
))
4870 /* source must exist */
4872 if (d_is_negative(old_dentry
))
4874 new_dentry
= __lookup_hash(&new_last
, new_path
.dentry
, lookup_flags
| target_flags
);
4875 error
= PTR_ERR(new_dentry
);
4876 if (IS_ERR(new_dentry
))
4879 if ((flags
& RENAME_NOREPLACE
) && d_is_positive(new_dentry
))
4881 if (flags
& RENAME_EXCHANGE
) {
4883 if (d_is_negative(new_dentry
))
4886 if (!d_is_dir(new_dentry
)) {
4888 if (new_last
.name
[new_last
.len
])
4892 /* unless the source is a directory trailing slashes give -ENOTDIR */
4893 if (!d_is_dir(old_dentry
)) {
4895 if (old_last
.name
[old_last
.len
])
4897 if (!(flags
& RENAME_EXCHANGE
) && new_last
.name
[new_last
.len
])
4900 /* source should not be ancestor of target */
4902 if (old_dentry
== trap
)
4904 /* target should not be an ancestor of source */
4905 if (!(flags
& RENAME_EXCHANGE
))
4907 if (new_dentry
== trap
)
4910 error
= security_path_rename(&old_path
, old_dentry
,
4911 &new_path
, new_dentry
, flags
);
4915 rd
.old_dir
= old_path
.dentry
->d_inode
;
4916 rd
.old_dentry
= old_dentry
;
4917 rd
.old_mnt_idmap
= mnt_idmap(old_path
.mnt
);
4918 rd
.new_dir
= new_path
.dentry
->d_inode
;
4919 rd
.new_dentry
= new_dentry
;
4920 rd
.new_mnt_idmap
= mnt_idmap(new_path
.mnt
);
4921 rd
.delegated_inode
= &delegated_inode
;
4923 error
= vfs_rename(&rd
);
4929 unlock_rename(new_path
.dentry
, old_path
.dentry
);
4930 if (delegated_inode
) {
4931 error
= break_deleg_wait(&delegated_inode
);
4935 mnt_drop_write(old_path
.mnt
);
4937 if (retry_estale(error
, lookup_flags
))
4938 should_retry
= true;
4939 path_put(&new_path
);
4941 path_put(&old_path
);
4943 should_retry
= false;
4944 lookup_flags
|= LOOKUP_REVAL
;
4953 SYSCALL_DEFINE5(renameat2
, int, olddfd
, const char __user
*, oldname
,
4954 int, newdfd
, const char __user
*, newname
, unsigned int, flags
)
4956 return do_renameat2(olddfd
, getname(oldname
), newdfd
, getname(newname
),
4960 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
4961 int, newdfd
, const char __user
*, newname
)
4963 return do_renameat2(olddfd
, getname(oldname
), newdfd
, getname(newname
),
4967 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
4969 return do_renameat2(AT_FDCWD
, getname(oldname
), AT_FDCWD
,
4970 getname(newname
), 0);
4973 int readlink_copy(char __user
*buffer
, int buflen
, const char *link
)
4975 int len
= PTR_ERR(link
);
4980 if (len
> (unsigned) buflen
)
4982 if (copy_to_user(buffer
, link
, len
))
4989 * vfs_readlink - copy symlink body into userspace buffer
4990 * @dentry: dentry on which to get symbolic link
4991 * @buffer: user memory pointer
4992 * @buflen: size of buffer
4994 * Does not touch atime. That's up to the caller if necessary
4996 * Does not call security hook.
4998 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
5000 struct inode
*inode
= d_inode(dentry
);
5001 DEFINE_DELAYED_CALL(done
);
5005 if (unlikely(!(inode
->i_opflags
& IOP_DEFAULT_READLINK
))) {
5006 if (unlikely(inode
->i_op
->readlink
))
5007 return inode
->i_op
->readlink(dentry
, buffer
, buflen
);
5009 if (!d_is_symlink(dentry
))
5012 spin_lock(&inode
->i_lock
);
5013 inode
->i_opflags
|= IOP_DEFAULT_READLINK
;
5014 spin_unlock(&inode
->i_lock
);
5017 link
= READ_ONCE(inode
->i_link
);
5019 link
= inode
->i_op
->get_link(dentry
, inode
, &done
);
5021 return PTR_ERR(link
);
5023 res
= readlink_copy(buffer
, buflen
, link
);
5024 do_delayed_call(&done
);
5027 EXPORT_SYMBOL(vfs_readlink
);
5030 * vfs_get_link - get symlink body
5031 * @dentry: dentry on which to get symbolic link
5032 * @done: caller needs to free returned data with this
5034 * Calls security hook and i_op->get_link() on the supplied inode.
5036 * It does not touch atime. That's up to the caller if necessary.
5038 * Does not work on "special" symlinks like /proc/$$/fd/N
5040 const char *vfs_get_link(struct dentry
*dentry
, struct delayed_call
*done
)
5042 const char *res
= ERR_PTR(-EINVAL
);
5043 struct inode
*inode
= d_inode(dentry
);
5045 if (d_is_symlink(dentry
)) {
5046 res
= ERR_PTR(security_inode_readlink(dentry
));
5048 res
= inode
->i_op
->get_link(dentry
, inode
, done
);
5052 EXPORT_SYMBOL(vfs_get_link
);
5054 /* get the link contents into pagecache */
5055 const char *page_get_link(struct dentry
*dentry
, struct inode
*inode
,
5056 struct delayed_call
*callback
)
5060 struct address_space
*mapping
= inode
->i_mapping
;
5063 page
= find_get_page(mapping
, 0);
5065 return ERR_PTR(-ECHILD
);
5066 if (!PageUptodate(page
)) {
5068 return ERR_PTR(-ECHILD
);
5071 page
= read_mapping_page(mapping
, 0, NULL
);
5075 set_delayed_call(callback
, page_put_link
, page
);
5076 BUG_ON(mapping_gfp_mask(mapping
) & __GFP_HIGHMEM
);
5077 kaddr
= page_address(page
);
5078 nd_terminate_link(kaddr
, inode
->i_size
, PAGE_SIZE
- 1);
5082 EXPORT_SYMBOL(page_get_link
);
5084 void page_put_link(void *arg
)
5088 EXPORT_SYMBOL(page_put_link
);
5090 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
5092 DEFINE_DELAYED_CALL(done
);
5093 int res
= readlink_copy(buffer
, buflen
,
5094 page_get_link(dentry
, d_inode(dentry
),
5096 do_delayed_call(&done
);
5099 EXPORT_SYMBOL(page_readlink
);
5101 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
5103 struct address_space
*mapping
= inode
->i_mapping
;
5104 const struct address_space_operations
*aops
= mapping
->a_ops
;
5105 bool nofs
= !mapping_gfp_constraint(mapping
, __GFP_FS
);
5107 void *fsdata
= NULL
;
5113 flags
= memalloc_nofs_save();
5114 err
= aops
->write_begin(NULL
, mapping
, 0, len
-1, &page
, &fsdata
);
5116 memalloc_nofs_restore(flags
);
5120 memcpy(page_address(page
), symname
, len
-1);
5122 err
= aops
->write_end(NULL
, mapping
, 0, len
-1, len
-1,
5129 mark_inode_dirty(inode
);
5134 EXPORT_SYMBOL(page_symlink
);
5136 const struct inode_operations page_symlink_inode_operations
= {
5137 .get_link
= page_get_link
,
5139 EXPORT_SYMBOL(page_symlink_inode_operations
);