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/namei.h>
24 #include <linux/pagemap.h>
25 #include <linux/sched/mm.h>
26 #include <linux/fsnotify.h>
27 #include <linux/personality.h>
28 #include <linux/security.h>
29 #include <linux/ima.h>
30 #include <linux/syscalls.h>
31 #include <linux/mount.h>
32 #include <linux/audit.h>
33 #include <linux/capability.h>
34 #include <linux/file.h>
35 #include <linux/fcntl.h>
36 #include <linux/device_cgroup.h>
37 #include <linux/fs_struct.h>
38 #include <linux/posix_acl.h>
39 #include <linux/hash.h>
40 #include <linux/bitops.h>
41 #include <linux/init_task.h>
42 #include <linux/uaccess.h>
47 /* [Feb-1997 T. Schoebel-Theuer]
48 * Fundamental changes in the pathname lookup mechanisms (namei)
49 * were necessary because of omirr. The reason is that omirr needs
50 * to know the _real_ pathname, not the user-supplied one, in case
51 * of symlinks (and also when transname replacements occur).
53 * The new code replaces the old recursive symlink resolution with
54 * an iterative one (in case of non-nested symlink chains). It does
55 * this with calls to <fs>_follow_link().
56 * As a side effect, dir_namei(), _namei() and follow_link() are now
57 * replaced with a single function lookup_dentry() that can handle all
58 * the special cases of the former code.
60 * With the new dcache, the pathname is stored at each inode, at least as
61 * long as the refcount of the inode is positive. As a side effect, the
62 * size of the dcache depends on the inode cache and thus is dynamic.
64 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
65 * resolution to correspond with current state of the code.
67 * Note that the symlink resolution is not *completely* iterative.
68 * There is still a significant amount of tail- and mid- recursion in
69 * the algorithm. Also, note that <fs>_readlink() is not used in
70 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
71 * may return different results than <fs>_follow_link(). Many virtual
72 * filesystems (including /proc) exhibit this behavior.
75 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
76 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
77 * and the name already exists in form of a symlink, try to create the new
78 * name indicated by the symlink. The old code always complained that the
79 * name already exists, due to not following the symlink even if its target
80 * is nonexistent. The new semantics affects also mknod() and link() when
81 * the name is a symlink pointing to a non-existent name.
83 * I don't know which semantics is the right one, since I have no access
84 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
85 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
86 * "old" one. Personally, I think the new semantics is much more logical.
87 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
88 * file does succeed in both HP-UX and SunOs, but not in Solaris
89 * and in the old Linux semantics.
92 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
93 * semantics. See the comments in "open_namei" and "do_link" below.
95 * [10-Sep-98 Alan Modra] Another symlink change.
98 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
99 * inside the path - always follow.
100 * in the last component in creation/removal/renaming - never follow.
101 * if LOOKUP_FOLLOW passed - follow.
102 * if the pathname has trailing slashes - follow.
103 * otherwise - don't follow.
104 * (applied in that order).
106 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
107 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
108 * During the 2.4 we need to fix the userland stuff depending on it -
109 * hopefully we will be able to get rid of that wart in 2.5. So far only
110 * XEmacs seems to be relying on it...
113 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
114 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
115 * any extra contention...
118 /* In order to reduce some races, while at the same time doing additional
119 * checking and hopefully speeding things up, we copy filenames to the
120 * kernel data space before using them..
122 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
123 * PATH_MAX includes the nul terminator --RR.
126 #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname))
129 getname_flags(const char __user
*filename
, int flags
, int *empty
)
131 struct filename
*result
;
135 result
= audit_reusename(filename
);
139 result
= __getname();
140 if (unlikely(!result
))
141 return ERR_PTR(-ENOMEM
);
144 * First, try to embed the struct filename inside the names_cache
147 kname
= (char *)result
->iname
;
148 result
->name
= kname
;
150 len
= strncpy_from_user(kname
, filename
, EMBEDDED_NAME_MAX
);
151 if (unlikely(len
< 0)) {
157 * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
158 * separate struct filename so we can dedicate the entire
159 * names_cache allocation for the pathname, and re-do the copy from
162 if (unlikely(len
== EMBEDDED_NAME_MAX
)) {
163 const size_t size
= offsetof(struct filename
, iname
[1]);
164 kname
= (char *)result
;
167 * size is chosen that way we to guarantee that
168 * result->iname[0] is within the same object and that
169 * kname can't be equal to result->iname, no matter what.
171 result
= kzalloc(size
, GFP_KERNEL
);
172 if (unlikely(!result
)) {
174 return ERR_PTR(-ENOMEM
);
176 result
->name
= kname
;
177 len
= strncpy_from_user(kname
, filename
, PATH_MAX
);
178 if (unlikely(len
< 0)) {
183 if (unlikely(len
== PATH_MAX
)) {
186 return ERR_PTR(-ENAMETOOLONG
);
191 /* The empty path is special. */
192 if (unlikely(!len
)) {
195 if (!(flags
& LOOKUP_EMPTY
)) {
197 return ERR_PTR(-ENOENT
);
201 result
->uptr
= filename
;
202 result
->aname
= NULL
;
203 audit_getname(result
);
208 getname_uflags(const char __user
*filename
, int uflags
)
210 int flags
= (uflags
& AT_EMPTY_PATH
) ? LOOKUP_EMPTY
: 0;
212 return getname_flags(filename
, flags
, NULL
);
216 getname(const char __user
* filename
)
218 return getname_flags(filename
, 0, NULL
);
222 getname_kernel(const char * filename
)
224 struct filename
*result
;
225 int len
= strlen(filename
) + 1;
227 result
= __getname();
228 if (unlikely(!result
))
229 return ERR_PTR(-ENOMEM
);
231 if (len
<= EMBEDDED_NAME_MAX
) {
232 result
->name
= (char *)result
->iname
;
233 } else if (len
<= PATH_MAX
) {
234 const size_t size
= offsetof(struct filename
, iname
[1]);
235 struct filename
*tmp
;
237 tmp
= kmalloc(size
, GFP_KERNEL
);
238 if (unlikely(!tmp
)) {
240 return ERR_PTR(-ENOMEM
);
242 tmp
->name
= (char *)result
;
246 return ERR_PTR(-ENAMETOOLONG
);
248 memcpy((char *)result
->name
, filename
, len
);
250 result
->aname
= NULL
;
252 audit_getname(result
);
257 void putname(struct filename
*name
)
262 BUG_ON(name
->refcnt
<= 0);
264 if (--name
->refcnt
> 0)
267 if (name
->name
!= name
->iname
) {
268 __putname(name
->name
);
275 * check_acl - perform ACL permission checking
276 * @mnt_userns: user namespace of the mount the inode was found from
277 * @inode: inode to check permissions on
278 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...)
280 * This function performs the ACL permission checking. Since this function
281 * retrieve POSIX acls it needs to know whether it is called from a blocking or
282 * non-blocking context and thus cares about the MAY_NOT_BLOCK bit.
284 * If the inode has been found through an idmapped mount the user namespace of
285 * the vfsmount must be passed through @mnt_userns. This function will then take
286 * care to map the inode according to @mnt_userns before checking permissions.
287 * On non-idmapped mounts or if permission checking is to be performed on the
288 * raw inode simply passs init_user_ns.
290 static int check_acl(struct user_namespace
*mnt_userns
,
291 struct inode
*inode
, int mask
)
293 #ifdef CONFIG_FS_POSIX_ACL
294 struct posix_acl
*acl
;
296 if (mask
& MAY_NOT_BLOCK
) {
297 acl
= get_cached_acl_rcu(inode
, ACL_TYPE_ACCESS
);
300 /* no ->get_inode_acl() calls in RCU mode... */
301 if (is_uncached_acl(acl
))
303 return posix_acl_permission(mnt_userns
, inode
, acl
, mask
);
306 acl
= get_inode_acl(inode
, ACL_TYPE_ACCESS
);
310 int error
= posix_acl_permission(mnt_userns
, inode
, acl
, mask
);
311 posix_acl_release(acl
);
320 * acl_permission_check - perform basic UNIX permission checking
321 * @mnt_userns: user namespace of the mount the inode was found from
322 * @inode: inode to check permissions on
323 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...)
325 * This function performs the basic UNIX permission checking. Since this
326 * function may retrieve POSIX acls it needs to know whether it is called from a
327 * blocking or non-blocking context and thus cares about the MAY_NOT_BLOCK bit.
329 * If the inode has been found through an idmapped mount the user namespace of
330 * the vfsmount must be passed through @mnt_userns. This function will then take
331 * care to map the inode according to @mnt_userns before checking permissions.
332 * On non-idmapped mounts or if permission checking is to be performed on the
333 * raw inode simply passs init_user_ns.
335 static int acl_permission_check(struct user_namespace
*mnt_userns
,
336 struct inode
*inode
, int mask
)
338 unsigned int mode
= inode
->i_mode
;
341 /* Are we the owner? If so, ACL's don't matter */
342 vfsuid
= i_uid_into_vfsuid(mnt_userns
, inode
);
343 if (likely(vfsuid_eq_kuid(vfsuid
, current_fsuid()))) {
346 return (mask
& ~mode
) ? -EACCES
: 0;
349 /* Do we have ACL's? */
350 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
)) {
351 int error
= check_acl(mnt_userns
, inode
, mask
);
352 if (error
!= -EAGAIN
)
356 /* Only RWX matters for group/other mode bits */
360 * Are the group permissions different from
361 * the other permissions in the bits we care
362 * about? Need to check group ownership if so.
364 if (mask
& (mode
^ (mode
>> 3))) {
365 vfsgid_t vfsgid
= i_gid_into_vfsgid(mnt_userns
, inode
);
366 if (vfsgid_in_group_p(vfsgid
))
370 /* Bits in 'mode' clear that we require? */
371 return (mask
& ~mode
) ? -EACCES
: 0;
375 * generic_permission - check for access rights on a Posix-like filesystem
376 * @mnt_userns: user namespace of the mount the inode was found from
377 * @inode: inode to check access rights for
378 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC,
379 * %MAY_NOT_BLOCK ...)
381 * Used to check for read/write/execute permissions on a file.
382 * We use "fsuid" for this, letting us set arbitrary permissions
383 * for filesystem access without changing the "normal" uids which
384 * are used for other things.
386 * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
387 * request cannot be satisfied (eg. requires blocking or too much complexity).
388 * It would then be called again in ref-walk mode.
390 * If the inode has been found through an idmapped mount the user namespace of
391 * the vfsmount must be passed through @mnt_userns. This function will then take
392 * care to map the inode according to @mnt_userns before checking permissions.
393 * On non-idmapped mounts or if permission checking is to be performed on the
394 * raw inode simply passs init_user_ns.
396 int generic_permission(struct user_namespace
*mnt_userns
, struct inode
*inode
,
402 * Do the basic permission checks.
404 ret
= acl_permission_check(mnt_userns
, inode
, mask
);
408 if (S_ISDIR(inode
->i_mode
)) {
409 /* DACs are overridable for directories */
410 if (!(mask
& MAY_WRITE
))
411 if (capable_wrt_inode_uidgid(mnt_userns
, inode
,
412 CAP_DAC_READ_SEARCH
))
414 if (capable_wrt_inode_uidgid(mnt_userns
, inode
,
421 * Searching includes executable on directories, else just read.
423 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
424 if (mask
== MAY_READ
)
425 if (capable_wrt_inode_uidgid(mnt_userns
, inode
,
426 CAP_DAC_READ_SEARCH
))
429 * Read/write DACs are always overridable.
430 * Executable DACs are overridable when there is
431 * at least one exec bit set.
433 if (!(mask
& MAY_EXEC
) || (inode
->i_mode
& S_IXUGO
))
434 if (capable_wrt_inode_uidgid(mnt_userns
, inode
,
440 EXPORT_SYMBOL(generic_permission
);
443 * do_inode_permission - UNIX permission checking
444 * @mnt_userns: user namespace of the mount the inode was found from
445 * @inode: inode to check permissions on
446 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...)
448 * We _really_ want to just do "generic_permission()" without
449 * even looking at the inode->i_op values. So we keep a cache
450 * flag in inode->i_opflags, that says "this has not special
451 * permission function, use the fast case".
453 static inline int do_inode_permission(struct user_namespace
*mnt_userns
,
454 struct inode
*inode
, int mask
)
456 if (unlikely(!(inode
->i_opflags
& IOP_FASTPERM
))) {
457 if (likely(inode
->i_op
->permission
))
458 return inode
->i_op
->permission(mnt_userns
, inode
, mask
);
460 /* This gets set once for the inode lifetime */
461 spin_lock(&inode
->i_lock
);
462 inode
->i_opflags
|= IOP_FASTPERM
;
463 spin_unlock(&inode
->i_lock
);
465 return generic_permission(mnt_userns
, inode
, mask
);
469 * sb_permission - Check superblock-level permissions
470 * @sb: Superblock of inode to check permission on
471 * @inode: Inode to check permission on
472 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
474 * Separate out file-system wide checks from inode-specific permission checks.
476 static int sb_permission(struct super_block
*sb
, struct inode
*inode
, int mask
)
478 if (unlikely(mask
& MAY_WRITE
)) {
479 umode_t mode
= inode
->i_mode
;
481 /* Nobody gets write access to a read-only fs. */
482 if (sb_rdonly(sb
) && (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
489 * inode_permission - Check for access rights to a given inode
490 * @mnt_userns: User namespace of the mount the inode was found from
491 * @inode: Inode to check permission on
492 * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
494 * Check for read/write/execute permissions on an inode. We use fs[ug]id for
495 * this, letting us set arbitrary permissions for filesystem access without
496 * changing the "normal" UIDs which are used for other things.
498 * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
500 int inode_permission(struct user_namespace
*mnt_userns
,
501 struct inode
*inode
, int mask
)
505 retval
= sb_permission(inode
->i_sb
, inode
, mask
);
509 if (unlikely(mask
& MAY_WRITE
)) {
511 * Nobody gets write access to an immutable file.
513 if (IS_IMMUTABLE(inode
))
517 * Updating mtime will likely cause i_uid and i_gid to be
518 * written back improperly if their true value is unknown
521 if (HAS_UNMAPPED_ID(mnt_userns
, inode
))
525 retval
= do_inode_permission(mnt_userns
, inode
, mask
);
529 retval
= devcgroup_inode_permission(inode
, mask
);
533 return security_inode_permission(inode
, mask
);
535 EXPORT_SYMBOL(inode_permission
);
538 * path_get - get a reference to a path
539 * @path: path to get the reference to
541 * Given a path increment the reference count to the dentry and the vfsmount.
543 void path_get(const struct path
*path
)
548 EXPORT_SYMBOL(path_get
);
551 * path_put - put a reference to a path
552 * @path: path to put the reference to
554 * Given a path decrement the reference count to the dentry and the vfsmount.
556 void path_put(const struct path
*path
)
561 EXPORT_SYMBOL(path_put
);
563 #define EMBEDDED_LEVELS 2
568 struct inode
*inode
; /* path.dentry.d_inode */
569 unsigned int flags
, state
;
570 unsigned seq
, next_seq
, m_seq
, r_seq
;
573 int total_link_count
;
576 struct delayed_call done
;
579 } *stack
, internal
[EMBEDDED_LEVELS
];
580 struct filename
*name
;
581 struct nameidata
*saved
;
586 } __randomize_layout
;
588 #define ND_ROOT_PRESET 1
589 #define ND_ROOT_GRABBED 2
592 static void __set_nameidata(struct nameidata
*p
, int dfd
, struct filename
*name
)
594 struct nameidata
*old
= current
->nameidata
;
595 p
->stack
= p
->internal
;
600 p
->path
.dentry
= NULL
;
601 p
->total_link_count
= old
? old
->total_link_count
: 0;
603 current
->nameidata
= p
;
606 static inline void set_nameidata(struct nameidata
*p
, int dfd
, struct filename
*name
,
607 const struct path
*root
)
609 __set_nameidata(p
, dfd
, name
);
611 if (unlikely(root
)) {
612 p
->state
= ND_ROOT_PRESET
;
617 static void restore_nameidata(void)
619 struct nameidata
*now
= current
->nameidata
, *old
= now
->saved
;
621 current
->nameidata
= old
;
623 old
->total_link_count
= now
->total_link_count
;
624 if (now
->stack
!= now
->internal
)
628 static bool nd_alloc_stack(struct nameidata
*nd
)
632 p
= kmalloc_array(MAXSYMLINKS
, sizeof(struct saved
),
633 nd
->flags
& LOOKUP_RCU
? GFP_ATOMIC
: GFP_KERNEL
);
636 memcpy(p
, nd
->internal
, sizeof(nd
->internal
));
642 * path_connected - Verify that a dentry is below mnt.mnt_root
644 * Rename can sometimes move a file or directory outside of a bind
645 * mount, path_connected allows those cases to be detected.
647 static bool path_connected(struct vfsmount
*mnt
, struct dentry
*dentry
)
649 struct super_block
*sb
= mnt
->mnt_sb
;
651 /* Bind mounts can have disconnected paths */
652 if (mnt
->mnt_root
== sb
->s_root
)
655 return is_subdir(dentry
, mnt
->mnt_root
);
658 static void drop_links(struct nameidata
*nd
)
662 struct saved
*last
= nd
->stack
+ i
;
663 do_delayed_call(&last
->done
);
664 clear_delayed_call(&last
->done
);
668 static void leave_rcu(struct nameidata
*nd
)
670 nd
->flags
&= ~LOOKUP_RCU
;
671 nd
->seq
= nd
->next_seq
= 0;
675 static void terminate_walk(struct nameidata
*nd
)
678 if (!(nd
->flags
& LOOKUP_RCU
)) {
681 for (i
= 0; i
< nd
->depth
; i
++)
682 path_put(&nd
->stack
[i
].link
);
683 if (nd
->state
& ND_ROOT_GRABBED
) {
685 nd
->state
&= ~ND_ROOT_GRABBED
;
692 nd
->path
.dentry
= NULL
;
695 /* path_put is needed afterwards regardless of success or failure */
696 static bool __legitimize_path(struct path
*path
, unsigned seq
, unsigned mseq
)
698 int res
= __legitimize_mnt(path
->mnt
, mseq
);
705 if (unlikely(!lockref_get_not_dead(&path
->dentry
->d_lockref
))) {
709 return !read_seqcount_retry(&path
->dentry
->d_seq
, seq
);
712 static inline bool legitimize_path(struct nameidata
*nd
,
713 struct path
*path
, unsigned seq
)
715 return __legitimize_path(path
, seq
, nd
->m_seq
);
718 static bool legitimize_links(struct nameidata
*nd
)
721 if (unlikely(nd
->flags
& LOOKUP_CACHED
)) {
726 for (i
= 0; i
< nd
->depth
; i
++) {
727 struct saved
*last
= nd
->stack
+ i
;
728 if (unlikely(!legitimize_path(nd
, &last
->link
, last
->seq
))) {
737 static bool legitimize_root(struct nameidata
*nd
)
739 /* Nothing to do if nd->root is zero or is managed by the VFS user. */
740 if (!nd
->root
.mnt
|| (nd
->state
& ND_ROOT_PRESET
))
742 nd
->state
|= ND_ROOT_GRABBED
;
743 return legitimize_path(nd
, &nd
->root
, nd
->root_seq
);
747 * Path walking has 2 modes, rcu-walk and ref-walk (see
748 * Documentation/filesystems/path-lookup.txt). In situations when we can't
749 * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
750 * normal reference counts on dentries and vfsmounts to transition to ref-walk
751 * mode. Refcounts are grabbed at the last known good point before rcu-walk
752 * got stuck, so ref-walk may continue from there. If this is not successful
753 * (eg. a seqcount has changed), then failure is returned and it's up to caller
754 * to restart the path walk from the beginning in ref-walk mode.
758 * try_to_unlazy - try to switch to ref-walk mode.
759 * @nd: nameidata pathwalk data
760 * Returns: true on success, false on failure
762 * try_to_unlazy attempts to legitimize the current nd->path and nd->root
764 * Must be called from rcu-walk context.
765 * Nothing should touch nameidata between try_to_unlazy() failure and
768 static bool try_to_unlazy(struct nameidata
*nd
)
770 struct dentry
*parent
= nd
->path
.dentry
;
772 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
774 if (unlikely(!legitimize_links(nd
)))
776 if (unlikely(!legitimize_path(nd
, &nd
->path
, nd
->seq
)))
778 if (unlikely(!legitimize_root(nd
)))
781 BUG_ON(nd
->inode
!= parent
->d_inode
);
786 nd
->path
.dentry
= NULL
;
793 * try_to_unlazy_next - try to switch to ref-walk mode.
794 * @nd: nameidata pathwalk data
795 * @dentry: next dentry to step into
796 * Returns: true on success, false on failure
798 * Similar to try_to_unlazy(), but here we have the next dentry already
799 * picked by rcu-walk and want to legitimize that in addition to the current
800 * nd->path and nd->root for ref-walk mode. Must be called from rcu-walk context.
801 * Nothing should touch nameidata between try_to_unlazy_next() failure and
804 static bool try_to_unlazy_next(struct nameidata
*nd
, struct dentry
*dentry
)
807 BUG_ON(!(nd
->flags
& LOOKUP_RCU
));
809 if (unlikely(!legitimize_links(nd
)))
811 res
= __legitimize_mnt(nd
->path
.mnt
, nd
->m_seq
);
817 if (unlikely(!lockref_get_not_dead(&nd
->path
.dentry
->d_lockref
)))
821 * We need to move both the parent and the dentry from the RCU domain
822 * to be properly refcounted. And the sequence number in the dentry
823 * validates *both* dentry counters, since we checked the sequence
824 * number of the parent after we got the child sequence number. So we
825 * know the parent must still be valid if the child sequence number is
827 if (unlikely(!lockref_get_not_dead(&dentry
->d_lockref
)))
829 if (read_seqcount_retry(&dentry
->d_seq
, nd
->next_seq
))
832 * Sequence counts matched. Now make sure that the root is
833 * still valid and get it if required.
835 if (unlikely(!legitimize_root(nd
)))
843 nd
->path
.dentry
= NULL
;
853 static inline int d_revalidate(struct dentry
*dentry
, unsigned int flags
)
855 if (unlikely(dentry
->d_flags
& DCACHE_OP_REVALIDATE
))
856 return dentry
->d_op
->d_revalidate(dentry
, flags
);
862 * complete_walk - successful completion of path walk
863 * @nd: pointer nameidata
865 * If we had been in RCU mode, drop out of it and legitimize nd->path.
866 * Revalidate the final result, unless we'd already done that during
867 * the path walk or the filesystem doesn't ask for it. Return 0 on
868 * success, -error on failure. In case of failure caller does not
869 * need to drop nd->path.
871 static int complete_walk(struct nameidata
*nd
)
873 struct dentry
*dentry
= nd
->path
.dentry
;
876 if (nd
->flags
& LOOKUP_RCU
) {
878 * We don't want to zero nd->root for scoped-lookups or
879 * externally-managed nd->root.
881 if (!(nd
->state
& ND_ROOT_PRESET
))
882 if (!(nd
->flags
& LOOKUP_IS_SCOPED
))
884 nd
->flags
&= ~LOOKUP_CACHED
;
885 if (!try_to_unlazy(nd
))
889 if (unlikely(nd
->flags
& LOOKUP_IS_SCOPED
)) {
891 * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't
892 * ever step outside the root during lookup" and should already
893 * be guaranteed by the rest of namei, we want to avoid a namei
894 * BUG resulting in userspace being given a path that was not
895 * scoped within the root at some point during the lookup.
897 * So, do a final sanity-check to make sure that in the
898 * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED)
899 * we won't silently return an fd completely outside of the
900 * requested root to userspace.
902 * Userspace could move the path outside the root after this
903 * check, but as discussed elsewhere this is not a concern (the
904 * resolved file was inside the root at some point).
906 if (!path_is_under(&nd
->path
, &nd
->root
))
910 if (likely(!(nd
->state
& ND_JUMPED
)))
913 if (likely(!(dentry
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
)))
916 status
= dentry
->d_op
->d_weak_revalidate(dentry
, nd
->flags
);
926 static int set_root(struct nameidata
*nd
)
928 struct fs_struct
*fs
= current
->fs
;
931 * Jumping to the real root in a scoped-lookup is a BUG in namei, but we
932 * still have to ensure it doesn't happen because it will cause a breakout
935 if (WARN_ON(nd
->flags
& LOOKUP_IS_SCOPED
))
936 return -ENOTRECOVERABLE
;
938 if (nd
->flags
& LOOKUP_RCU
) {
942 seq
= read_seqcount_begin(&fs
->seq
);
944 nd
->root_seq
= __read_seqcount_begin(&nd
->root
.dentry
->d_seq
);
945 } while (read_seqcount_retry(&fs
->seq
, seq
));
947 get_fs_root(fs
, &nd
->root
);
948 nd
->state
|= ND_ROOT_GRABBED
;
953 static int nd_jump_root(struct nameidata
*nd
)
955 if (unlikely(nd
->flags
& LOOKUP_BENEATH
))
957 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
)) {
958 /* Absolute path arguments to path_init() are allowed. */
959 if (nd
->path
.mnt
!= NULL
&& nd
->path
.mnt
!= nd
->root
.mnt
)
963 int error
= set_root(nd
);
967 if (nd
->flags
& LOOKUP_RCU
) {
971 nd
->inode
= d
->d_inode
;
972 nd
->seq
= nd
->root_seq
;
973 if (read_seqcount_retry(&d
->d_seq
, nd
->seq
))
979 nd
->inode
= nd
->path
.dentry
->d_inode
;
981 nd
->state
|= ND_JUMPED
;
986 * Helper to directly jump to a known parsed path from ->get_link,
987 * caller must have taken a reference to path beforehand.
989 int nd_jump_link(const struct path
*path
)
992 struct nameidata
*nd
= current
->nameidata
;
994 if (unlikely(nd
->flags
& LOOKUP_NO_MAGICLINKS
))
998 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
)) {
999 if (nd
->path
.mnt
!= path
->mnt
)
1002 /* Not currently safe for scoped-lookups. */
1003 if (unlikely(nd
->flags
& LOOKUP_IS_SCOPED
))
1006 path_put(&nd
->path
);
1008 nd
->inode
= nd
->path
.dentry
->d_inode
;
1009 nd
->state
|= ND_JUMPED
;
1017 static inline void put_link(struct nameidata
*nd
)
1019 struct saved
*last
= nd
->stack
+ --nd
->depth
;
1020 do_delayed_call(&last
->done
);
1021 if (!(nd
->flags
& LOOKUP_RCU
))
1022 path_put(&last
->link
);
1025 static int sysctl_protected_symlinks __read_mostly
;
1026 static int sysctl_protected_hardlinks __read_mostly
;
1027 static int sysctl_protected_fifos __read_mostly
;
1028 static int sysctl_protected_regular __read_mostly
;
1030 #ifdef CONFIG_SYSCTL
1031 static struct ctl_table namei_sysctls
[] = {
1033 .procname
= "protected_symlinks",
1034 .data
= &sysctl_protected_symlinks
,
1035 .maxlen
= sizeof(int),
1037 .proc_handler
= proc_dointvec_minmax
,
1038 .extra1
= SYSCTL_ZERO
,
1039 .extra2
= SYSCTL_ONE
,
1042 .procname
= "protected_hardlinks",
1043 .data
= &sysctl_protected_hardlinks
,
1044 .maxlen
= sizeof(int),
1046 .proc_handler
= proc_dointvec_minmax
,
1047 .extra1
= SYSCTL_ZERO
,
1048 .extra2
= SYSCTL_ONE
,
1051 .procname
= "protected_fifos",
1052 .data
= &sysctl_protected_fifos
,
1053 .maxlen
= sizeof(int),
1055 .proc_handler
= proc_dointvec_minmax
,
1056 .extra1
= SYSCTL_ZERO
,
1057 .extra2
= SYSCTL_TWO
,
1060 .procname
= "protected_regular",
1061 .data
= &sysctl_protected_regular
,
1062 .maxlen
= sizeof(int),
1064 .proc_handler
= proc_dointvec_minmax
,
1065 .extra1
= SYSCTL_ZERO
,
1066 .extra2
= SYSCTL_TWO
,
1071 static int __init
init_fs_namei_sysctls(void)
1073 register_sysctl_init("fs", namei_sysctls
);
1076 fs_initcall(init_fs_namei_sysctls
);
1078 #endif /* CONFIG_SYSCTL */
1081 * may_follow_link - Check symlink following for unsafe situations
1082 * @nd: nameidata pathwalk data
1084 * In the case of the sysctl_protected_symlinks sysctl being enabled,
1085 * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
1086 * in a sticky world-writable directory. This is to protect privileged
1087 * processes from failing races against path names that may change out
1088 * from under them by way of other users creating malicious symlinks.
1089 * It will permit symlinks to be followed only when outside a sticky
1090 * world-writable directory, or when the uid of the symlink and follower
1091 * match, or when the directory owner matches the symlink's owner.
1093 * Returns 0 if following the symlink is allowed, -ve on error.
1095 static inline int may_follow_link(struct nameidata
*nd
, const struct inode
*inode
)
1097 struct user_namespace
*mnt_userns
;
1100 if (!sysctl_protected_symlinks
)
1103 mnt_userns
= mnt_user_ns(nd
->path
.mnt
);
1104 vfsuid
= i_uid_into_vfsuid(mnt_userns
, inode
);
1105 /* Allowed if owner and follower match. */
1106 if (vfsuid_eq_kuid(vfsuid
, current_fsuid()))
1109 /* Allowed if parent directory not sticky and world-writable. */
1110 if ((nd
->dir_mode
& (S_ISVTX
|S_IWOTH
)) != (S_ISVTX
|S_IWOTH
))
1113 /* Allowed if parent directory and link owner match. */
1114 if (vfsuid_valid(nd
->dir_vfsuid
) && vfsuid_eq(nd
->dir_vfsuid
, vfsuid
))
1117 if (nd
->flags
& LOOKUP_RCU
)
1120 audit_inode(nd
->name
, nd
->stack
[0].link
.dentry
, 0);
1121 audit_log_path_denied(AUDIT_ANOM_LINK
, "follow_link");
1126 * safe_hardlink_source - Check for safe hardlink conditions
1127 * @mnt_userns: user namespace of the mount the inode was found from
1128 * @inode: the source inode to hardlink from
1130 * Return false if at least one of the following conditions:
1131 * - inode is not a regular file
1133 * - inode is setgid and group-exec
1134 * - access failure for read and write
1136 * Otherwise returns true.
1138 static bool safe_hardlink_source(struct user_namespace
*mnt_userns
,
1139 struct inode
*inode
)
1141 umode_t mode
= inode
->i_mode
;
1143 /* Special files should not get pinned to the filesystem. */
1147 /* Setuid files should not get pinned to the filesystem. */
1151 /* Executable setgid files should not get pinned to the filesystem. */
1152 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
))
1155 /* Hardlinking to unreadable or unwritable sources is dangerous. */
1156 if (inode_permission(mnt_userns
, inode
, MAY_READ
| MAY_WRITE
))
1163 * may_linkat - Check permissions for creating a hardlink
1164 * @mnt_userns: user namespace of the mount the inode was found from
1165 * @link: the source to hardlink from
1167 * Block hardlink when all of:
1168 * - sysctl_protected_hardlinks enabled
1169 * - fsuid does not match inode
1170 * - hardlink source is unsafe (see safe_hardlink_source() above)
1171 * - not CAP_FOWNER in a namespace with the inode owner uid mapped
1173 * If the inode has been found through an idmapped mount the user namespace of
1174 * the vfsmount must be passed through @mnt_userns. This function will then take
1175 * care to map the inode according to @mnt_userns before checking permissions.
1176 * On non-idmapped mounts or if permission checking is to be performed on the
1177 * raw inode simply passs init_user_ns.
1179 * Returns 0 if successful, -ve on error.
1181 int may_linkat(struct user_namespace
*mnt_userns
, const struct path
*link
)
1183 struct inode
*inode
= link
->dentry
->d_inode
;
1185 /* Inode writeback is not safe when the uid or gid are invalid. */
1186 if (!vfsuid_valid(i_uid_into_vfsuid(mnt_userns
, inode
)) ||
1187 !vfsgid_valid(i_gid_into_vfsgid(mnt_userns
, inode
)))
1190 if (!sysctl_protected_hardlinks
)
1193 /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
1194 * otherwise, it must be a safe source.
1196 if (safe_hardlink_source(mnt_userns
, inode
) ||
1197 inode_owner_or_capable(mnt_userns
, inode
))
1200 audit_log_path_denied(AUDIT_ANOM_LINK
, "linkat");
1205 * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory
1206 * should be allowed, or not, on files that already
1208 * @mnt_userns: user namespace of the mount the inode was found from
1209 * @nd: nameidata pathwalk data
1210 * @inode: the inode of the file to open
1212 * Block an O_CREAT open of a FIFO (or a regular file) when:
1213 * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled
1214 * - the file already exists
1215 * - we are in a sticky directory
1216 * - we don't own the file
1217 * - the owner of the directory doesn't own the file
1218 * - the directory is world writable
1219 * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2
1220 * the directory doesn't have to be world writable: being group writable will
1223 * If the inode has been found through an idmapped mount the user namespace of
1224 * the vfsmount must be passed through @mnt_userns. This function will then take
1225 * care to map the inode according to @mnt_userns before checking permissions.
1226 * On non-idmapped mounts or if permission checking is to be performed on the
1227 * raw inode simply passs init_user_ns.
1229 * Returns 0 if the open is allowed, -ve on error.
1231 static int may_create_in_sticky(struct user_namespace
*mnt_userns
,
1232 struct nameidata
*nd
, struct inode
*const inode
)
1234 umode_t dir_mode
= nd
->dir_mode
;
1235 vfsuid_t dir_vfsuid
= nd
->dir_vfsuid
;
1237 if ((!sysctl_protected_fifos
&& S_ISFIFO(inode
->i_mode
)) ||
1238 (!sysctl_protected_regular
&& S_ISREG(inode
->i_mode
)) ||
1239 likely(!(dir_mode
& S_ISVTX
)) ||
1240 vfsuid_eq(i_uid_into_vfsuid(mnt_userns
, inode
), dir_vfsuid
) ||
1241 vfsuid_eq_kuid(i_uid_into_vfsuid(mnt_userns
, inode
), current_fsuid()))
1244 if (likely(dir_mode
& 0002) ||
1246 ((sysctl_protected_fifos
>= 2 && S_ISFIFO(inode
->i_mode
)) ||
1247 (sysctl_protected_regular
>= 2 && S_ISREG(inode
->i_mode
))))) {
1248 const char *operation
= S_ISFIFO(inode
->i_mode
) ?
1249 "sticky_create_fifo" :
1250 "sticky_create_regular";
1251 audit_log_path_denied(AUDIT_ANOM_CREAT
, operation
);
1258 * follow_up - Find the mountpoint of path's vfsmount
1260 * Given a path, find the mountpoint of its source file system.
1261 * Replace @path with the path of the mountpoint in the parent mount.
1264 * Return 1 if we went up a level and 0 if we were already at the
1267 int follow_up(struct path
*path
)
1269 struct mount
*mnt
= real_mount(path
->mnt
);
1270 struct mount
*parent
;
1271 struct dentry
*mountpoint
;
1273 read_seqlock_excl(&mount_lock
);
1274 parent
= mnt
->mnt_parent
;
1275 if (parent
== mnt
) {
1276 read_sequnlock_excl(&mount_lock
);
1279 mntget(&parent
->mnt
);
1280 mountpoint
= dget(mnt
->mnt_mountpoint
);
1281 read_sequnlock_excl(&mount_lock
);
1283 path
->dentry
= mountpoint
;
1285 path
->mnt
= &parent
->mnt
;
1288 EXPORT_SYMBOL(follow_up
);
1290 static bool choose_mountpoint_rcu(struct mount
*m
, const struct path
*root
,
1291 struct path
*path
, unsigned *seqp
)
1293 while (mnt_has_parent(m
)) {
1294 struct dentry
*mountpoint
= m
->mnt_mountpoint
;
1297 if (unlikely(root
->dentry
== mountpoint
&&
1298 root
->mnt
== &m
->mnt
))
1300 if (mountpoint
!= m
->mnt
.mnt_root
) {
1301 path
->mnt
= &m
->mnt
;
1302 path
->dentry
= mountpoint
;
1303 *seqp
= read_seqcount_begin(&mountpoint
->d_seq
);
1310 static bool choose_mountpoint(struct mount
*m
, const struct path
*root
,
1317 unsigned seq
, mseq
= read_seqbegin(&mount_lock
);
1319 found
= choose_mountpoint_rcu(m
, root
, path
, &seq
);
1320 if (unlikely(!found
)) {
1321 if (!read_seqretry(&mount_lock
, mseq
))
1324 if (likely(__legitimize_path(path
, seq
, mseq
)))
1336 * Perform an automount
1337 * - return -EISDIR to tell follow_managed() to stop and return the path we
1340 static int follow_automount(struct path
*path
, int *count
, unsigned lookup_flags
)
1342 struct dentry
*dentry
= path
->dentry
;
1344 /* We don't want to mount if someone's just doing a stat -
1345 * unless they're stat'ing a directory and appended a '/' to
1348 * We do, however, want to mount if someone wants to open or
1349 * create a file of any type under the mountpoint, wants to
1350 * traverse through the mountpoint or wants to open the
1351 * mounted directory. Also, autofs may mark negative dentries
1352 * as being automount points. These will need the attentions
1353 * of the daemon to instantiate them before they can be used.
1355 if (!(lookup_flags
& (LOOKUP_PARENT
| LOOKUP_DIRECTORY
|
1356 LOOKUP_OPEN
| LOOKUP_CREATE
| LOOKUP_AUTOMOUNT
)) &&
1360 if (count
&& (*count
)++ >= MAXSYMLINKS
)
1363 return finish_automount(dentry
->d_op
->d_automount(path
), path
);
1367 * mount traversal - out-of-line part. One note on ->d_flags accesses -
1368 * dentries are pinned but not locked here, so negative dentry can go
1369 * positive right under us. Use of smp_load_acquire() provides a barrier
1370 * sufficient for ->d_inode and ->d_flags consistency.
1372 static int __traverse_mounts(struct path
*path
, unsigned flags
, bool *jumped
,
1373 int *count
, unsigned lookup_flags
)
1375 struct vfsmount
*mnt
= path
->mnt
;
1376 bool need_mntput
= false;
1379 while (flags
& DCACHE_MANAGED_DENTRY
) {
1380 /* Allow the filesystem to manage the transit without i_mutex
1382 if (flags
& DCACHE_MANAGE_TRANSIT
) {
1383 ret
= path
->dentry
->d_op
->d_manage(path
, false);
1384 flags
= smp_load_acquire(&path
->dentry
->d_flags
);
1389 if (flags
& DCACHE_MOUNTED
) { // something's mounted on it..
1390 struct vfsmount
*mounted
= lookup_mnt(path
);
1391 if (mounted
) { // ... in our namespace
1395 path
->mnt
= mounted
;
1396 path
->dentry
= dget(mounted
->mnt_root
);
1397 // here we know it's positive
1398 flags
= path
->dentry
->d_flags
;
1404 if (!(flags
& DCACHE_NEED_AUTOMOUNT
))
1407 // uncovered automount point
1408 ret
= follow_automount(path
, count
, lookup_flags
);
1409 flags
= smp_load_acquire(&path
->dentry
->d_flags
);
1416 // possible if you race with several mount --move
1417 if (need_mntput
&& path
->mnt
== mnt
)
1419 if (!ret
&& unlikely(d_flags_negative(flags
)))
1421 *jumped
= need_mntput
;
1425 static inline int traverse_mounts(struct path
*path
, bool *jumped
,
1426 int *count
, unsigned lookup_flags
)
1428 unsigned flags
= smp_load_acquire(&path
->dentry
->d_flags
);
1431 if (likely(!(flags
& DCACHE_MANAGED_DENTRY
))) {
1433 if (unlikely(d_flags_negative(flags
)))
1437 return __traverse_mounts(path
, flags
, jumped
, count
, lookup_flags
);
1440 int follow_down_one(struct path
*path
)
1442 struct vfsmount
*mounted
;
1444 mounted
= lookup_mnt(path
);
1448 path
->mnt
= mounted
;
1449 path
->dentry
= dget(mounted
->mnt_root
);
1454 EXPORT_SYMBOL(follow_down_one
);
1457 * Follow down to the covering mount currently visible to userspace. At each
1458 * point, the filesystem owning that dentry may be queried as to whether the
1459 * caller is permitted to proceed or not.
1461 int follow_down(struct path
*path
)
1463 struct vfsmount
*mnt
= path
->mnt
;
1465 int ret
= traverse_mounts(path
, &jumped
, NULL
, 0);
1467 if (path
->mnt
!= mnt
)
1471 EXPORT_SYMBOL(follow_down
);
1474 * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
1475 * we meet a managed dentry that would need blocking.
1477 static bool __follow_mount_rcu(struct nameidata
*nd
, struct path
*path
)
1479 struct dentry
*dentry
= path
->dentry
;
1480 unsigned int flags
= dentry
->d_flags
;
1482 if (likely(!(flags
& DCACHE_MANAGED_DENTRY
)))
1485 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
))
1490 * Don't forget we might have a non-mountpoint managed dentry
1491 * that wants to block transit.
1493 if (unlikely(flags
& DCACHE_MANAGE_TRANSIT
)) {
1494 int res
= dentry
->d_op
->d_manage(path
, true);
1496 return res
== -EISDIR
;
1497 flags
= dentry
->d_flags
;
1500 if (flags
& DCACHE_MOUNTED
) {
1501 struct mount
*mounted
= __lookup_mnt(path
->mnt
, dentry
);
1503 path
->mnt
= &mounted
->mnt
;
1504 dentry
= path
->dentry
= mounted
->mnt
.mnt_root
;
1505 nd
->state
|= ND_JUMPED
;
1506 nd
->next_seq
= read_seqcount_begin(&dentry
->d_seq
);
1507 flags
= dentry
->d_flags
;
1508 // makes sure that non-RCU pathwalk could reach
1510 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1514 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1517 return !(flags
& DCACHE_NEED_AUTOMOUNT
);
1521 static inline int handle_mounts(struct nameidata
*nd
, struct dentry
*dentry
,
1527 path
->mnt
= nd
->path
.mnt
;
1528 path
->dentry
= dentry
;
1529 if (nd
->flags
& LOOKUP_RCU
) {
1530 unsigned int seq
= nd
->next_seq
;
1531 if (likely(__follow_mount_rcu(nd
, path
)))
1533 // *path and nd->next_seq might've been clobbered
1534 path
->mnt
= nd
->path
.mnt
;
1535 path
->dentry
= dentry
;
1537 if (!try_to_unlazy_next(nd
, dentry
))
1540 ret
= traverse_mounts(path
, &jumped
, &nd
->total_link_count
, nd
->flags
);
1542 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
))
1545 nd
->state
|= ND_JUMPED
;
1547 if (unlikely(ret
)) {
1549 if (path
->mnt
!= nd
->path
.mnt
)
1556 * This looks up the name in dcache and possibly revalidates the found dentry.
1557 * NULL is returned if the dentry does not exist in the cache.
1559 static struct dentry
*lookup_dcache(const struct qstr
*name
,
1563 struct dentry
*dentry
= d_lookup(dir
, name
);
1565 int error
= d_revalidate(dentry
, flags
);
1566 if (unlikely(error
<= 0)) {
1568 d_invalidate(dentry
);
1570 return ERR_PTR(error
);
1577 * Parent directory has inode locked exclusive. This is one
1578 * and only case when ->lookup() gets called on non in-lookup
1579 * dentries - as the matter of fact, this only gets called
1580 * when directory is guaranteed to have no in-lookup children
1583 static struct dentry
*__lookup_hash(const struct qstr
*name
,
1584 struct dentry
*base
, unsigned int flags
)
1586 struct dentry
*dentry
= lookup_dcache(name
, base
, flags
);
1588 struct inode
*dir
= base
->d_inode
;
1593 /* Don't create child dentry for a dead directory. */
1594 if (unlikely(IS_DEADDIR(dir
)))
1595 return ERR_PTR(-ENOENT
);
1597 dentry
= d_alloc(base
, name
);
1598 if (unlikely(!dentry
))
1599 return ERR_PTR(-ENOMEM
);
1601 old
= dir
->i_op
->lookup(dir
, dentry
, flags
);
1602 if (unlikely(old
)) {
1609 static struct dentry
*lookup_fast(struct nameidata
*nd
)
1611 struct dentry
*dentry
, *parent
= nd
->path
.dentry
;
1615 * Rename seqlock is not required here because in the off chance
1616 * of a false negative due to a concurrent rename, the caller is
1617 * going to fall back to non-racy lookup.
1619 if (nd
->flags
& LOOKUP_RCU
) {
1620 dentry
= __d_lookup_rcu(parent
, &nd
->last
, &nd
->next_seq
);
1621 if (unlikely(!dentry
)) {
1622 if (!try_to_unlazy(nd
))
1623 return ERR_PTR(-ECHILD
);
1628 * This sequence count validates that the parent had no
1629 * changes while we did the lookup of the dentry above.
1631 if (read_seqcount_retry(&parent
->d_seq
, nd
->seq
))
1632 return ERR_PTR(-ECHILD
);
1634 status
= d_revalidate(dentry
, nd
->flags
);
1635 if (likely(status
> 0))
1637 if (!try_to_unlazy_next(nd
, dentry
))
1638 return ERR_PTR(-ECHILD
);
1639 if (status
== -ECHILD
)
1640 /* we'd been told to redo it in non-rcu mode */
1641 status
= d_revalidate(dentry
, nd
->flags
);
1643 dentry
= __d_lookup(parent
, &nd
->last
);
1644 if (unlikely(!dentry
))
1646 status
= d_revalidate(dentry
, nd
->flags
);
1648 if (unlikely(status
<= 0)) {
1650 d_invalidate(dentry
);
1652 return ERR_PTR(status
);
1657 /* Fast lookup failed, do it the slow way */
1658 static struct dentry
*__lookup_slow(const struct qstr
*name
,
1662 struct dentry
*dentry
, *old
;
1663 struct inode
*inode
= dir
->d_inode
;
1664 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq
);
1666 /* Don't go there if it's already dead */
1667 if (unlikely(IS_DEADDIR(inode
)))
1668 return ERR_PTR(-ENOENT
);
1670 dentry
= d_alloc_parallel(dir
, name
, &wq
);
1673 if (unlikely(!d_in_lookup(dentry
))) {
1674 int error
= d_revalidate(dentry
, flags
);
1675 if (unlikely(error
<= 0)) {
1677 d_invalidate(dentry
);
1682 dentry
= ERR_PTR(error
);
1685 old
= inode
->i_op
->lookup(inode
, dentry
, flags
);
1686 d_lookup_done(dentry
);
1687 if (unlikely(old
)) {
1695 static struct dentry
*lookup_slow(const struct qstr
*name
,
1699 struct inode
*inode
= dir
->d_inode
;
1701 inode_lock_shared(inode
);
1702 res
= __lookup_slow(name
, dir
, flags
);
1703 inode_unlock_shared(inode
);
1707 static inline int may_lookup(struct user_namespace
*mnt_userns
,
1708 struct nameidata
*nd
)
1710 if (nd
->flags
& LOOKUP_RCU
) {
1711 int err
= inode_permission(mnt_userns
, nd
->inode
, MAY_EXEC
|MAY_NOT_BLOCK
);
1712 if (err
!= -ECHILD
|| !try_to_unlazy(nd
))
1715 return inode_permission(mnt_userns
, nd
->inode
, MAY_EXEC
);
1718 static int reserve_stack(struct nameidata
*nd
, struct path
*link
)
1720 if (unlikely(nd
->total_link_count
++ >= MAXSYMLINKS
))
1723 if (likely(nd
->depth
!= EMBEDDED_LEVELS
))
1725 if (likely(nd
->stack
!= nd
->internal
))
1727 if (likely(nd_alloc_stack(nd
)))
1730 if (nd
->flags
& LOOKUP_RCU
) {
1731 // we need to grab link before we do unlazy. And we can't skip
1732 // unlazy even if we fail to grab the link - cleanup needs it
1733 bool grabbed_link
= legitimize_path(nd
, link
, nd
->next_seq
);
1735 if (!try_to_unlazy(nd
) || !grabbed_link
)
1738 if (nd_alloc_stack(nd
))
1744 enum {WALK_TRAILING
= 1, WALK_MORE
= 2, WALK_NOFOLLOW
= 4};
1746 static const char *pick_link(struct nameidata
*nd
, struct path
*link
,
1747 struct inode
*inode
, int flags
)
1751 int error
= reserve_stack(nd
, link
);
1753 if (unlikely(error
)) {
1754 if (!(nd
->flags
& LOOKUP_RCU
))
1756 return ERR_PTR(error
);
1758 last
= nd
->stack
+ nd
->depth
++;
1760 clear_delayed_call(&last
->done
);
1761 last
->seq
= nd
->next_seq
;
1763 if (flags
& WALK_TRAILING
) {
1764 error
= may_follow_link(nd
, inode
);
1765 if (unlikely(error
))
1766 return ERR_PTR(error
);
1769 if (unlikely(nd
->flags
& LOOKUP_NO_SYMLINKS
) ||
1770 unlikely(link
->mnt
->mnt_flags
& MNT_NOSYMFOLLOW
))
1771 return ERR_PTR(-ELOOP
);
1773 if (!(nd
->flags
& LOOKUP_RCU
)) {
1774 touch_atime(&last
->link
);
1776 } else if (atime_needs_update(&last
->link
, inode
)) {
1777 if (!try_to_unlazy(nd
))
1778 return ERR_PTR(-ECHILD
);
1779 touch_atime(&last
->link
);
1782 error
= security_inode_follow_link(link
->dentry
, inode
,
1783 nd
->flags
& LOOKUP_RCU
);
1784 if (unlikely(error
))
1785 return ERR_PTR(error
);
1787 res
= READ_ONCE(inode
->i_link
);
1789 const char * (*get
)(struct dentry
*, struct inode
*,
1790 struct delayed_call
*);
1791 get
= inode
->i_op
->get_link
;
1792 if (nd
->flags
& LOOKUP_RCU
) {
1793 res
= get(NULL
, inode
, &last
->done
);
1794 if (res
== ERR_PTR(-ECHILD
) && try_to_unlazy(nd
))
1795 res
= get(link
->dentry
, inode
, &last
->done
);
1797 res
= get(link
->dentry
, inode
, &last
->done
);
1805 error
= nd_jump_root(nd
);
1806 if (unlikely(error
))
1807 return ERR_PTR(error
);
1808 while (unlikely(*++res
== '/'))
1813 all_done
: // pure jump
1819 * Do we need to follow links? We _really_ want to be able
1820 * to do this check without having to look at inode->i_op,
1821 * so we keep a cache of "no, this doesn't need follow_link"
1822 * for the common case.
1824 * NOTE: dentry must be what nd->next_seq had been sampled from.
1826 static const char *step_into(struct nameidata
*nd
, int flags
,
1827 struct dentry
*dentry
)
1830 struct inode
*inode
;
1831 int err
= handle_mounts(nd
, dentry
, &path
);
1834 return ERR_PTR(err
);
1835 inode
= path
.dentry
->d_inode
;
1836 if (likely(!d_is_symlink(path
.dentry
)) ||
1837 ((flags
& WALK_TRAILING
) && !(nd
->flags
& LOOKUP_FOLLOW
)) ||
1838 (flags
& WALK_NOFOLLOW
)) {
1839 /* not a symlink or should not follow */
1840 if (nd
->flags
& LOOKUP_RCU
) {
1841 if (read_seqcount_retry(&path
.dentry
->d_seq
, nd
->next_seq
))
1842 return ERR_PTR(-ECHILD
);
1843 if (unlikely(!inode
))
1844 return ERR_PTR(-ENOENT
);
1846 dput(nd
->path
.dentry
);
1847 if (nd
->path
.mnt
!= path
.mnt
)
1848 mntput(nd
->path
.mnt
);
1852 nd
->seq
= nd
->next_seq
;
1855 if (nd
->flags
& LOOKUP_RCU
) {
1856 /* make sure that d_is_symlink above matches inode */
1857 if (read_seqcount_retry(&path
.dentry
->d_seq
, nd
->next_seq
))
1858 return ERR_PTR(-ECHILD
);
1860 if (path
.mnt
== nd
->path
.mnt
)
1863 return pick_link(nd
, &path
, inode
, flags
);
1866 static struct dentry
*follow_dotdot_rcu(struct nameidata
*nd
)
1868 struct dentry
*parent
, *old
;
1870 if (path_equal(&nd
->path
, &nd
->root
))
1872 if (unlikely(nd
->path
.dentry
== nd
->path
.mnt
->mnt_root
)) {
1875 if (!choose_mountpoint_rcu(real_mount(nd
->path
.mnt
),
1876 &nd
->root
, &path
, &seq
))
1878 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
))
1879 return ERR_PTR(-ECHILD
);
1881 nd
->inode
= path
.dentry
->d_inode
;
1883 // makes sure that non-RCU pathwalk could reach this state
1884 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1885 return ERR_PTR(-ECHILD
);
1886 /* we know that mountpoint was pinned */
1888 old
= nd
->path
.dentry
;
1889 parent
= old
->d_parent
;
1890 nd
->next_seq
= read_seqcount_begin(&parent
->d_seq
);
1891 // makes sure that non-RCU pathwalk could reach this state
1892 if (read_seqcount_retry(&old
->d_seq
, nd
->seq
))
1893 return ERR_PTR(-ECHILD
);
1894 if (unlikely(!path_connected(nd
->path
.mnt
, parent
)))
1895 return ERR_PTR(-ECHILD
);
1898 if (read_seqretry(&mount_lock
, nd
->m_seq
))
1899 return ERR_PTR(-ECHILD
);
1900 if (unlikely(nd
->flags
& LOOKUP_BENEATH
))
1901 return ERR_PTR(-ECHILD
);
1902 nd
->next_seq
= nd
->seq
;
1903 return nd
->path
.dentry
;
1906 static struct dentry
*follow_dotdot(struct nameidata
*nd
)
1908 struct dentry
*parent
;
1910 if (path_equal(&nd
->path
, &nd
->root
))
1912 if (unlikely(nd
->path
.dentry
== nd
->path
.mnt
->mnt_root
)) {
1915 if (!choose_mountpoint(real_mount(nd
->path
.mnt
),
1918 path_put(&nd
->path
);
1920 nd
->inode
= path
.dentry
->d_inode
;
1921 if (unlikely(nd
->flags
& LOOKUP_NO_XDEV
))
1922 return ERR_PTR(-EXDEV
);
1924 /* rare case of legitimate dget_parent()... */
1925 parent
= dget_parent(nd
->path
.dentry
);
1926 if (unlikely(!path_connected(nd
->path
.mnt
, parent
))) {
1928 return ERR_PTR(-ENOENT
);
1933 if (unlikely(nd
->flags
& LOOKUP_BENEATH
))
1934 return ERR_PTR(-EXDEV
);
1935 return dget(nd
->path
.dentry
);
1938 static const char *handle_dots(struct nameidata
*nd
, int type
)
1940 if (type
== LAST_DOTDOT
) {
1941 const char *error
= NULL
;
1942 struct dentry
*parent
;
1944 if (!nd
->root
.mnt
) {
1945 error
= ERR_PTR(set_root(nd
));
1949 if (nd
->flags
& LOOKUP_RCU
)
1950 parent
= follow_dotdot_rcu(nd
);
1952 parent
= follow_dotdot(nd
);
1954 return ERR_CAST(parent
);
1955 error
= step_into(nd
, WALK_NOFOLLOW
, parent
);
1956 if (unlikely(error
))
1959 if (unlikely(nd
->flags
& LOOKUP_IS_SCOPED
)) {
1961 * If there was a racing rename or mount along our
1962 * path, then we can't be sure that ".." hasn't jumped
1963 * above nd->root (and so userspace should retry or use
1967 if (__read_seqcount_retry(&mount_lock
.seqcount
, nd
->m_seq
))
1968 return ERR_PTR(-EAGAIN
);
1969 if (__read_seqcount_retry(&rename_lock
.seqcount
, nd
->r_seq
))
1970 return ERR_PTR(-EAGAIN
);
1976 static const char *walk_component(struct nameidata
*nd
, int flags
)
1978 struct dentry
*dentry
;
1980 * "." and ".." are special - ".." especially so because it has
1981 * to be able to know about the current root directory and
1982 * parent relationships.
1984 if (unlikely(nd
->last_type
!= LAST_NORM
)) {
1985 if (!(flags
& WALK_MORE
) && nd
->depth
)
1987 return handle_dots(nd
, nd
->last_type
);
1989 dentry
= lookup_fast(nd
);
1991 return ERR_CAST(dentry
);
1992 if (unlikely(!dentry
)) {
1993 dentry
= lookup_slow(&nd
->last
, nd
->path
.dentry
, nd
->flags
);
1995 return ERR_CAST(dentry
);
1997 if (!(flags
& WALK_MORE
) && nd
->depth
)
1999 return step_into(nd
, flags
, dentry
);
2003 * We can do the critical dentry name comparison and hashing
2004 * operations one word at a time, but we are limited to:
2006 * - Architectures with fast unaligned word accesses. We could
2007 * do a "get_unaligned()" if this helps and is sufficiently
2010 * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
2011 * do not trap on the (extremely unlikely) case of a page
2012 * crossing operation.
2014 * - Furthermore, we need an efficient 64-bit compile for the
2015 * 64-bit case in order to generate the "number of bytes in
2016 * the final mask". Again, that could be replaced with a
2017 * efficient population count instruction or similar.
2019 #ifdef CONFIG_DCACHE_WORD_ACCESS
2021 #include <asm/word-at-a-time.h>
2025 /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */
2027 #elif defined(CONFIG_64BIT)
2029 * Register pressure in the mixing function is an issue, particularly
2030 * on 32-bit x86, but almost any function requires one state value and
2031 * one temporary. Instead, use a function designed for two state values
2032 * and no temporaries.
2034 * This function cannot create a collision in only two iterations, so
2035 * we have two iterations to achieve avalanche. In those two iterations,
2036 * we have six layers of mixing, which is enough to spread one bit's
2037 * influence out to 2^6 = 64 state bits.
2039 * Rotate constants are scored by considering either 64 one-bit input
2040 * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the
2041 * probability of that delta causing a change to each of the 128 output
2042 * bits, using a sample of random initial states.
2044 * The Shannon entropy of the computed probabilities is then summed
2045 * to produce a score. Ideally, any input change has a 50% chance of
2046 * toggling any given output bit.
2048 * Mixing scores (in bits) for (12,45):
2049 * Input delta: 1-bit 2-bit
2050 * 1 round: 713.3 42542.6
2051 * 2 rounds: 2753.7 140389.8
2052 * 3 rounds: 5954.1 233458.2
2053 * 4 rounds: 7862.6 256672.2
2054 * Perfect: 8192 258048
2055 * (64*128) (64*63/2 * 128)
2057 #define HASH_MIX(x, y, a) \
2059 y ^= x, x = rol64(x,12),\
2060 x += y, y = rol64(y,45),\
2064 * Fold two longs into one 32-bit hash value. This must be fast, but
2065 * latency isn't quite as critical, as there is a fair bit of additional
2066 * work done before the hash value is used.
2068 static inline unsigned int fold_hash(unsigned long x
, unsigned long y
)
2070 y
^= x
* GOLDEN_RATIO_64
;
2071 y
*= GOLDEN_RATIO_64
;
2075 #else /* 32-bit case */
2078 * Mixing scores (in bits) for (7,20):
2079 * Input delta: 1-bit 2-bit
2080 * 1 round: 330.3 9201.6
2081 * 2 rounds: 1246.4 25475.4
2082 * 3 rounds: 1907.1 31295.1
2083 * 4 rounds: 2042.3 31718.6
2084 * Perfect: 2048 31744
2085 * (32*64) (32*31/2 * 64)
2087 #define HASH_MIX(x, y, a) \
2089 y ^= x, x = rol32(x, 7),\
2090 x += y, y = rol32(y,20),\
2093 static inline unsigned int fold_hash(unsigned long x
, unsigned long y
)
2095 /* Use arch-optimized multiply if one exists */
2096 return __hash_32(y
^ __hash_32(x
));
2102 * Return the hash of a string of known length. This is carfully
2103 * designed to match hash_name(), which is the more critical function.
2104 * In particular, we must end by hashing a final word containing 0..7
2105 * payload bytes, to match the way that hash_name() iterates until it
2106 * finds the delimiter after the name.
2108 unsigned int full_name_hash(const void *salt
, const char *name
, unsigned int len
)
2110 unsigned long a
, x
= 0, y
= (unsigned long)salt
;
2115 a
= load_unaligned_zeropad(name
);
2116 if (len
< sizeof(unsigned long))
2119 name
+= sizeof(unsigned long);
2120 len
-= sizeof(unsigned long);
2122 x
^= a
& bytemask_from_count(len
);
2124 return fold_hash(x
, y
);
2126 EXPORT_SYMBOL(full_name_hash
);
2128 /* Return the "hash_len" (hash and length) of a null-terminated string */
2129 u64
hashlen_string(const void *salt
, const char *name
)
2131 unsigned long a
= 0, x
= 0, y
= (unsigned long)salt
;
2132 unsigned long adata
, mask
, len
;
2133 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
2140 len
+= sizeof(unsigned long);
2142 a
= load_unaligned_zeropad(name
+len
);
2143 } while (!has_zero(a
, &adata
, &constants
));
2145 adata
= prep_zero_mask(a
, adata
, &constants
);
2146 mask
= create_zero_mask(adata
);
2147 x
^= a
& zero_bytemask(mask
);
2149 return hashlen_create(fold_hash(x
, y
), len
+ find_zero(mask
));
2151 EXPORT_SYMBOL(hashlen_string
);
2154 * Calculate the length and hash of the path component, and
2155 * return the "hash_len" as the result.
2157 static inline u64
hash_name(const void *salt
, const char *name
)
2159 unsigned long a
= 0, b
, x
= 0, y
= (unsigned long)salt
;
2160 unsigned long adata
, bdata
, mask
, len
;
2161 const struct word_at_a_time constants
= WORD_AT_A_TIME_CONSTANTS
;
2168 len
+= sizeof(unsigned long);
2170 a
= load_unaligned_zeropad(name
+len
);
2171 b
= a
^ REPEAT_BYTE('/');
2172 } while (!(has_zero(a
, &adata
, &constants
) | has_zero(b
, &bdata
, &constants
)));
2174 adata
= prep_zero_mask(a
, adata
, &constants
);
2175 bdata
= prep_zero_mask(b
, bdata
, &constants
);
2176 mask
= create_zero_mask(adata
| bdata
);
2177 x
^= a
& zero_bytemask(mask
);
2179 return hashlen_create(fold_hash(x
, y
), len
+ find_zero(mask
));
2182 #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */
2184 /* Return the hash of a string of known length */
2185 unsigned int full_name_hash(const void *salt
, const char *name
, unsigned int len
)
2187 unsigned long hash
= init_name_hash(salt
);
2189 hash
= partial_name_hash((unsigned char)*name
++, hash
);
2190 return end_name_hash(hash
);
2192 EXPORT_SYMBOL(full_name_hash
);
2194 /* Return the "hash_len" (hash and length) of a null-terminated string */
2195 u64
hashlen_string(const void *salt
, const char *name
)
2197 unsigned long hash
= init_name_hash(salt
);
2198 unsigned long len
= 0, c
;
2200 c
= (unsigned char)*name
;
2203 hash
= partial_name_hash(c
, hash
);
2204 c
= (unsigned char)name
[len
];
2206 return hashlen_create(end_name_hash(hash
), len
);
2208 EXPORT_SYMBOL(hashlen_string
);
2211 * We know there's a real path component here of at least
2214 static inline u64
hash_name(const void *salt
, const char *name
)
2216 unsigned long hash
= init_name_hash(salt
);
2217 unsigned long len
= 0, c
;
2219 c
= (unsigned char)*name
;
2222 hash
= partial_name_hash(c
, hash
);
2223 c
= (unsigned char)name
[len
];
2224 } while (c
&& c
!= '/');
2225 return hashlen_create(end_name_hash(hash
), len
);
2232 * This is the basic name resolution function, turning a pathname into
2233 * the final dentry. We expect 'base' to be positive and a directory.
2235 * Returns 0 and nd will have valid dentry and mnt on success.
2236 * Returns error and drops reference to input namei data on failure.
2238 static int link_path_walk(const char *name
, struct nameidata
*nd
)
2240 int depth
= 0; // depth <= nd->depth
2243 nd
->last_type
= LAST_ROOT
;
2244 nd
->flags
|= LOOKUP_PARENT
;
2246 return PTR_ERR(name
);
2250 nd
->dir_mode
= 0; // short-circuit the 'hardening' idiocy
2254 /* At this point we know we have a real path component. */
2256 struct user_namespace
*mnt_userns
;
2261 mnt_userns
= mnt_user_ns(nd
->path
.mnt
);
2262 err
= may_lookup(mnt_userns
, nd
);
2266 hash_len
= hash_name(nd
->path
.dentry
, name
);
2269 if (name
[0] == '.') switch (hashlen_len(hash_len
)) {
2271 if (name
[1] == '.') {
2273 nd
->state
|= ND_JUMPED
;
2279 if (likely(type
== LAST_NORM
)) {
2280 struct dentry
*parent
= nd
->path
.dentry
;
2281 nd
->state
&= ~ND_JUMPED
;
2282 if (unlikely(parent
->d_flags
& DCACHE_OP_HASH
)) {
2283 struct qstr
this = { { .hash_len
= hash_len
}, .name
= name
};
2284 err
= parent
->d_op
->d_hash(parent
, &this);
2287 hash_len
= this.hash_len
;
2292 nd
->last
.hash_len
= hash_len
;
2293 nd
->last
.name
= name
;
2294 nd
->last_type
= type
;
2296 name
+= hashlen_len(hash_len
);
2300 * If it wasn't NUL, we know it was '/'. Skip that
2301 * slash, and continue until no more slashes.
2305 } while (unlikely(*name
== '/'));
2306 if (unlikely(!*name
)) {
2308 /* pathname or trailing symlink, done */
2310 nd
->dir_vfsuid
= i_uid_into_vfsuid(mnt_userns
, nd
->inode
);
2311 nd
->dir_mode
= nd
->inode
->i_mode
;
2312 nd
->flags
&= ~LOOKUP_PARENT
;
2315 /* last component of nested symlink */
2316 name
= nd
->stack
[--depth
].name
;
2317 link
= walk_component(nd
, 0);
2319 /* not the last component */
2320 link
= walk_component(nd
, WALK_MORE
);
2322 if (unlikely(link
)) {
2324 return PTR_ERR(link
);
2325 /* a symlink to follow */
2326 nd
->stack
[depth
++].name
= name
;
2330 if (unlikely(!d_can_lookup(nd
->path
.dentry
))) {
2331 if (nd
->flags
& LOOKUP_RCU
) {
2332 if (!try_to_unlazy(nd
))
2340 /* must be paired with terminate_walk() */
2341 static const char *path_init(struct nameidata
*nd
, unsigned flags
)
2344 const char *s
= nd
->name
->name
;
2346 /* LOOKUP_CACHED requires RCU, ask caller to retry */
2347 if ((flags
& (LOOKUP_RCU
| LOOKUP_CACHED
)) == LOOKUP_CACHED
)
2348 return ERR_PTR(-EAGAIN
);
2351 flags
&= ~LOOKUP_RCU
;
2352 if (flags
& LOOKUP_RCU
)
2355 nd
->seq
= nd
->next_seq
= 0;
2358 nd
->state
|= ND_JUMPED
;
2360 nd
->m_seq
= __read_seqcount_begin(&mount_lock
.seqcount
);
2361 nd
->r_seq
= __read_seqcount_begin(&rename_lock
.seqcount
);
2364 if (nd
->state
& ND_ROOT_PRESET
) {
2365 struct dentry
*root
= nd
->root
.dentry
;
2366 struct inode
*inode
= root
->d_inode
;
2367 if (*s
&& unlikely(!d_can_lookup(root
)))
2368 return ERR_PTR(-ENOTDIR
);
2369 nd
->path
= nd
->root
;
2371 if (flags
& LOOKUP_RCU
) {
2372 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2373 nd
->root_seq
= nd
->seq
;
2375 path_get(&nd
->path
);
2380 nd
->root
.mnt
= NULL
;
2382 /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */
2383 if (*s
== '/' && !(flags
& LOOKUP_IN_ROOT
)) {
2384 error
= nd_jump_root(nd
);
2385 if (unlikely(error
))
2386 return ERR_PTR(error
);
2390 /* Relative pathname -- get the starting-point it is relative to. */
2391 if (nd
->dfd
== AT_FDCWD
) {
2392 if (flags
& LOOKUP_RCU
) {
2393 struct fs_struct
*fs
= current
->fs
;
2397 seq
= read_seqcount_begin(&fs
->seq
);
2399 nd
->inode
= nd
->path
.dentry
->d_inode
;
2400 nd
->seq
= __read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2401 } while (read_seqcount_retry(&fs
->seq
, seq
));
2403 get_fs_pwd(current
->fs
, &nd
->path
);
2404 nd
->inode
= nd
->path
.dentry
->d_inode
;
2407 /* Caller must check execute permissions on the starting path component */
2408 struct fd f
= fdget_raw(nd
->dfd
);
2409 struct dentry
*dentry
;
2412 return ERR_PTR(-EBADF
);
2414 dentry
= f
.file
->f_path
.dentry
;
2416 if (*s
&& unlikely(!d_can_lookup(dentry
))) {
2418 return ERR_PTR(-ENOTDIR
);
2421 nd
->path
= f
.file
->f_path
;
2422 if (flags
& LOOKUP_RCU
) {
2423 nd
->inode
= nd
->path
.dentry
->d_inode
;
2424 nd
->seq
= read_seqcount_begin(&nd
->path
.dentry
->d_seq
);
2426 path_get(&nd
->path
);
2427 nd
->inode
= nd
->path
.dentry
->d_inode
;
2432 /* For scoped-lookups we need to set the root to the dirfd as well. */
2433 if (flags
& LOOKUP_IS_SCOPED
) {
2434 nd
->root
= nd
->path
;
2435 if (flags
& LOOKUP_RCU
) {
2436 nd
->root_seq
= nd
->seq
;
2438 path_get(&nd
->root
);
2439 nd
->state
|= ND_ROOT_GRABBED
;
2445 static inline const char *lookup_last(struct nameidata
*nd
)
2447 if (nd
->last_type
== LAST_NORM
&& nd
->last
.name
[nd
->last
.len
])
2448 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
2450 return walk_component(nd
, WALK_TRAILING
);
2453 static int handle_lookup_down(struct nameidata
*nd
)
2455 if (!(nd
->flags
& LOOKUP_RCU
))
2456 dget(nd
->path
.dentry
);
2457 nd
->next_seq
= nd
->seq
;
2458 return PTR_ERR(step_into(nd
, WALK_NOFOLLOW
, nd
->path
.dentry
));
2461 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2462 static int path_lookupat(struct nameidata
*nd
, unsigned flags
, struct path
*path
)
2464 const char *s
= path_init(nd
, flags
);
2467 if (unlikely(flags
& LOOKUP_DOWN
) && !IS_ERR(s
)) {
2468 err
= handle_lookup_down(nd
);
2469 if (unlikely(err
< 0))
2473 while (!(err
= link_path_walk(s
, nd
)) &&
2474 (s
= lookup_last(nd
)) != NULL
)
2476 if (!err
&& unlikely(nd
->flags
& LOOKUP_MOUNTPOINT
)) {
2477 err
= handle_lookup_down(nd
);
2478 nd
->state
&= ~ND_JUMPED
; // no d_weak_revalidate(), please...
2481 err
= complete_walk(nd
);
2483 if (!err
&& nd
->flags
& LOOKUP_DIRECTORY
)
2484 if (!d_can_lookup(nd
->path
.dentry
))
2488 nd
->path
.mnt
= NULL
;
2489 nd
->path
.dentry
= NULL
;
2495 int filename_lookup(int dfd
, struct filename
*name
, unsigned flags
,
2496 struct path
*path
, struct path
*root
)
2499 struct nameidata nd
;
2501 return PTR_ERR(name
);
2502 set_nameidata(&nd
, dfd
, name
, root
);
2503 retval
= path_lookupat(&nd
, flags
| LOOKUP_RCU
, path
);
2504 if (unlikely(retval
== -ECHILD
))
2505 retval
= path_lookupat(&nd
, flags
, path
);
2506 if (unlikely(retval
== -ESTALE
))
2507 retval
= path_lookupat(&nd
, flags
| LOOKUP_REVAL
, path
);
2509 if (likely(!retval
))
2510 audit_inode(name
, path
->dentry
,
2511 flags
& LOOKUP_MOUNTPOINT
? AUDIT_INODE_NOEVAL
: 0);
2512 restore_nameidata();
2516 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
2517 static int path_parentat(struct nameidata
*nd
, unsigned flags
,
2518 struct path
*parent
)
2520 const char *s
= path_init(nd
, flags
);
2521 int err
= link_path_walk(s
, nd
);
2523 err
= complete_walk(nd
);
2526 nd
->path
.mnt
= NULL
;
2527 nd
->path
.dentry
= NULL
;
2533 /* Note: this does not consume "name" */
2534 static int filename_parentat(int dfd
, struct filename
*name
,
2535 unsigned int flags
, struct path
*parent
,
2536 struct qstr
*last
, int *type
)
2539 struct nameidata nd
;
2542 return PTR_ERR(name
);
2543 set_nameidata(&nd
, dfd
, name
, NULL
);
2544 retval
= path_parentat(&nd
, flags
| LOOKUP_RCU
, parent
);
2545 if (unlikely(retval
== -ECHILD
))
2546 retval
= path_parentat(&nd
, flags
, parent
);
2547 if (unlikely(retval
== -ESTALE
))
2548 retval
= path_parentat(&nd
, flags
| LOOKUP_REVAL
, parent
);
2549 if (likely(!retval
)) {
2551 *type
= nd
.last_type
;
2552 audit_inode(name
, parent
->dentry
, AUDIT_INODE_PARENT
);
2554 restore_nameidata();
2558 /* does lookup, returns the object with parent locked */
2559 static struct dentry
*__kern_path_locked(struct filename
*name
, struct path
*path
)
2565 error
= filename_parentat(AT_FDCWD
, name
, 0, path
, &last
, &type
);
2567 return ERR_PTR(error
);
2568 if (unlikely(type
!= LAST_NORM
)) {
2570 return ERR_PTR(-EINVAL
);
2572 inode_lock_nested(path
->dentry
->d_inode
, I_MUTEX_PARENT
);
2573 d
= __lookup_hash(&last
, path
->dentry
, 0);
2575 inode_unlock(path
->dentry
->d_inode
);
2581 struct dentry
*kern_path_locked(const char *name
, struct path
*path
)
2583 struct filename
*filename
= getname_kernel(name
);
2584 struct dentry
*res
= __kern_path_locked(filename
, path
);
2590 int kern_path(const char *name
, unsigned int flags
, struct path
*path
)
2592 struct filename
*filename
= getname_kernel(name
);
2593 int ret
= filename_lookup(AT_FDCWD
, filename
, flags
, path
, NULL
);
2599 EXPORT_SYMBOL(kern_path
);
2602 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
2603 * @dentry: pointer to dentry of the base directory
2604 * @mnt: pointer to vfs mount of the base directory
2605 * @name: pointer to file name
2606 * @flags: lookup flags
2607 * @path: pointer to struct path to fill
2609 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
2610 const char *name
, unsigned int flags
,
2613 struct filename
*filename
;
2614 struct path root
= {.mnt
= mnt
, .dentry
= dentry
};
2617 filename
= getname_kernel(name
);
2618 /* the first argument of filename_lookup() is ignored with root */
2619 ret
= filename_lookup(AT_FDCWD
, filename
, flags
, path
, &root
);
2623 EXPORT_SYMBOL(vfs_path_lookup
);
2625 static int lookup_one_common(struct user_namespace
*mnt_userns
,
2626 const char *name
, struct dentry
*base
, int len
,
2631 this->hash
= full_name_hash(base
, name
, len
);
2635 if (unlikely(name
[0] == '.')) {
2636 if (len
< 2 || (len
== 2 && name
[1] == '.'))
2641 unsigned int c
= *(const unsigned char *)name
++;
2642 if (c
== '/' || c
== '\0')
2646 * See if the low-level filesystem might want
2647 * to use its own hash..
2649 if (base
->d_flags
& DCACHE_OP_HASH
) {
2650 int err
= base
->d_op
->d_hash(base
, this);
2655 return inode_permission(mnt_userns
, base
->d_inode
, MAY_EXEC
);
2659 * try_lookup_one_len - filesystem helper to lookup single pathname component
2660 * @name: pathname component to lookup
2661 * @base: base directory to lookup from
2662 * @len: maximum length @len should be interpreted to
2664 * Look up a dentry by name in the dcache, returning NULL if it does not
2665 * currently exist. The function does not try to create a dentry.
2667 * Note that this routine is purely a helper for filesystem usage and should
2668 * not be called by generic code.
2670 * The caller must hold base->i_mutex.
2672 struct dentry
*try_lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2677 WARN_ON_ONCE(!inode_is_locked(base
->d_inode
));
2679 err
= lookup_one_common(&init_user_ns
, name
, base
, len
, &this);
2681 return ERR_PTR(err
);
2683 return lookup_dcache(&this, base
, 0);
2685 EXPORT_SYMBOL(try_lookup_one_len
);
2688 * lookup_one_len - filesystem helper to lookup single pathname component
2689 * @name: pathname component to lookup
2690 * @base: base directory to lookup from
2691 * @len: maximum length @len should be interpreted to
2693 * Note that this routine is purely a helper for filesystem usage and should
2694 * not be called by generic code.
2696 * The caller must hold base->i_mutex.
2698 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
2700 struct dentry
*dentry
;
2704 WARN_ON_ONCE(!inode_is_locked(base
->d_inode
));
2706 err
= lookup_one_common(&init_user_ns
, name
, base
, len
, &this);
2708 return ERR_PTR(err
);
2710 dentry
= lookup_dcache(&this, base
, 0);
2711 return dentry
? dentry
: __lookup_slow(&this, base
, 0);
2713 EXPORT_SYMBOL(lookup_one_len
);
2716 * lookup_one - filesystem helper to lookup single pathname component
2717 * @mnt_userns: user namespace of the mount the lookup is performed from
2718 * @name: pathname component to lookup
2719 * @base: base directory to lookup from
2720 * @len: maximum length @len should be interpreted to
2722 * Note that this routine is purely a helper for filesystem usage and should
2723 * not be called by generic code.
2725 * The caller must hold base->i_mutex.
2727 struct dentry
*lookup_one(struct user_namespace
*mnt_userns
, const char *name
,
2728 struct dentry
*base
, int len
)
2730 struct dentry
*dentry
;
2734 WARN_ON_ONCE(!inode_is_locked(base
->d_inode
));
2736 err
= lookup_one_common(mnt_userns
, name
, base
, len
, &this);
2738 return ERR_PTR(err
);
2740 dentry
= lookup_dcache(&this, base
, 0);
2741 return dentry
? dentry
: __lookup_slow(&this, base
, 0);
2743 EXPORT_SYMBOL(lookup_one
);
2746 * lookup_one_unlocked - filesystem helper to lookup single pathname component
2747 * @mnt_userns: idmapping of the mount the lookup is performed from
2748 * @name: pathname component to lookup
2749 * @base: base directory to lookup from
2750 * @len: maximum length @len should be interpreted to
2752 * Note that this routine is purely a helper for filesystem usage and should
2753 * not be called by generic code.
2755 * Unlike lookup_one_len, it should be called without the parent
2756 * i_mutex held, and will take the i_mutex itself if necessary.
2758 struct dentry
*lookup_one_unlocked(struct user_namespace
*mnt_userns
,
2759 const char *name
, struct dentry
*base
,
2766 err
= lookup_one_common(mnt_userns
, name
, base
, len
, &this);
2768 return ERR_PTR(err
);
2770 ret
= lookup_dcache(&this, base
, 0);
2772 ret
= lookup_slow(&this, base
, 0);
2775 EXPORT_SYMBOL(lookup_one_unlocked
);
2778 * lookup_one_positive_unlocked - filesystem helper to lookup single
2779 * pathname component
2780 * @mnt_userns: idmapping of the mount the lookup is performed from
2781 * @name: pathname component to lookup
2782 * @base: base directory to lookup from
2783 * @len: maximum length @len should be interpreted to
2785 * This helper will yield ERR_PTR(-ENOENT) on negatives. The helper returns
2786 * known positive or ERR_PTR(). This is what most of the users want.
2788 * Note that pinned negative with unlocked parent _can_ become positive at any
2789 * time, so callers of lookup_one_unlocked() need to be very careful; pinned
2790 * positives have >d_inode stable, so this one avoids such problems.
2792 * Note that this routine is purely a helper for filesystem usage and should
2793 * not be called by generic code.
2795 * The helper should be called without i_mutex held.
2797 struct dentry
*lookup_one_positive_unlocked(struct user_namespace
*mnt_userns
,
2799 struct dentry
*base
, int len
)
2801 struct dentry
*ret
= lookup_one_unlocked(mnt_userns
, name
, base
, len
);
2803 if (!IS_ERR(ret
) && d_flags_negative(smp_load_acquire(&ret
->d_flags
))) {
2805 ret
= ERR_PTR(-ENOENT
);
2809 EXPORT_SYMBOL(lookup_one_positive_unlocked
);
2812 * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
2813 * @name: pathname component to lookup
2814 * @base: base directory to lookup from
2815 * @len: maximum length @len should be interpreted to
2817 * Note that this routine is purely a helper for filesystem usage and should
2818 * not be called by generic code.
2820 * Unlike lookup_one_len, it should be called without the parent
2821 * i_mutex held, and will take the i_mutex itself if necessary.
2823 struct dentry
*lookup_one_len_unlocked(const char *name
,
2824 struct dentry
*base
, int len
)
2826 return lookup_one_unlocked(&init_user_ns
, name
, base
, len
);
2828 EXPORT_SYMBOL(lookup_one_len_unlocked
);
2831 * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT)
2832 * on negatives. Returns known positive or ERR_PTR(); that's what
2833 * most of the users want. Note that pinned negative with unlocked parent
2834 * _can_ become positive at any time, so callers of lookup_one_len_unlocked()
2835 * need to be very careful; pinned positives have ->d_inode stable, so
2836 * this one avoids such problems.
2838 struct dentry
*lookup_positive_unlocked(const char *name
,
2839 struct dentry
*base
, int len
)
2841 return lookup_one_positive_unlocked(&init_user_ns
, name
, base
, len
);
2843 EXPORT_SYMBOL(lookup_positive_unlocked
);
2845 #ifdef CONFIG_UNIX98_PTYS
2846 int path_pts(struct path
*path
)
2848 /* Find something mounted on "pts" in the same directory as
2851 struct dentry
*parent
= dget_parent(path
->dentry
);
2852 struct dentry
*child
;
2853 struct qstr
this = QSTR_INIT("pts", 3);
2855 if (unlikely(!path_connected(path
->mnt
, parent
))) {
2860 path
->dentry
= parent
;
2861 child
= d_hash_and_lookup(parent
, &this);
2865 path
->dentry
= child
;
2872 int user_path_at_empty(int dfd
, const char __user
*name
, unsigned flags
,
2873 struct path
*path
, int *empty
)
2875 struct filename
*filename
= getname_flags(name
, flags
, empty
);
2876 int ret
= filename_lookup(dfd
, filename
, flags
, path
, NULL
);
2881 EXPORT_SYMBOL(user_path_at_empty
);
2883 int __check_sticky(struct user_namespace
*mnt_userns
, struct inode
*dir
,
2884 struct inode
*inode
)
2886 kuid_t fsuid
= current_fsuid();
2888 if (vfsuid_eq_kuid(i_uid_into_vfsuid(mnt_userns
, inode
), fsuid
))
2890 if (vfsuid_eq_kuid(i_uid_into_vfsuid(mnt_userns
, dir
), fsuid
))
2892 return !capable_wrt_inode_uidgid(mnt_userns
, inode
, CAP_FOWNER
);
2894 EXPORT_SYMBOL(__check_sticky
);
2897 * Check whether we can remove a link victim from directory dir, check
2898 * whether the type of victim is right.
2899 * 1. We can't do it if dir is read-only (done in permission())
2900 * 2. We should have write and exec permissions on dir
2901 * 3. We can't remove anything from append-only dir
2902 * 4. We can't do anything with immutable dir (done in permission())
2903 * 5. If the sticky bit on dir is set we should either
2904 * a. be owner of dir, or
2905 * b. be owner of victim, or
2906 * c. have CAP_FOWNER capability
2907 * 6. If the victim is append-only or immutable we can't do antyhing with
2908 * links pointing to it.
2909 * 7. If the victim has an unknown uid or gid we can't change the inode.
2910 * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR.
2911 * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR.
2912 * 10. We can't remove a root or mountpoint.
2913 * 11. We don't allow removal of NFS sillyrenamed files; it's handled by
2914 * nfs_async_unlink().
2916 static int may_delete(struct user_namespace
*mnt_userns
, struct inode
*dir
,
2917 struct dentry
*victim
, bool isdir
)
2919 struct inode
*inode
= d_backing_inode(victim
);
2922 if (d_is_negative(victim
))
2926 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
2928 /* Inode writeback is not safe when the uid or gid are invalid. */
2929 if (!vfsuid_valid(i_uid_into_vfsuid(mnt_userns
, inode
)) ||
2930 !vfsgid_valid(i_gid_into_vfsgid(mnt_userns
, inode
)))
2933 audit_inode_child(dir
, victim
, AUDIT_TYPE_CHILD_DELETE
);
2935 error
= inode_permission(mnt_userns
, dir
, MAY_WRITE
| MAY_EXEC
);
2941 if (check_sticky(mnt_userns
, dir
, inode
) || IS_APPEND(inode
) ||
2942 IS_IMMUTABLE(inode
) || IS_SWAPFILE(inode
) ||
2943 HAS_UNMAPPED_ID(mnt_userns
, inode
))
2946 if (!d_is_dir(victim
))
2948 if (IS_ROOT(victim
))
2950 } else if (d_is_dir(victim
))
2952 if (IS_DEADDIR(dir
))
2954 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
2959 /* Check whether we can create an object with dentry child in directory
2961 * 1. We can't do it if child already exists (open has special treatment for
2962 * this case, but since we are inlined it's OK)
2963 * 2. We can't do it if dir is read-only (done in permission())
2964 * 3. We can't do it if the fs can't represent the fsuid or fsgid.
2965 * 4. We should have write and exec permissions on dir
2966 * 5. We can't do it if dir is immutable (done in permission())
2968 static inline int may_create(struct user_namespace
*mnt_userns
,
2969 struct inode
*dir
, struct dentry
*child
)
2971 audit_inode_child(dir
, child
, AUDIT_TYPE_CHILD_CREATE
);
2974 if (IS_DEADDIR(dir
))
2976 if (!fsuidgid_has_mapping(dir
->i_sb
, mnt_userns
))
2979 return inode_permission(mnt_userns
, dir
, MAY_WRITE
| MAY_EXEC
);
2983 * p1 and p2 should be directories on the same fs.
2985 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
2990 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
2994 mutex_lock(&p1
->d_sb
->s_vfs_rename_mutex
);
2996 p
= d_ancestor(p2
, p1
);
2998 inode_lock_nested(p2
->d_inode
, I_MUTEX_PARENT
);
2999 inode_lock_nested(p1
->d_inode
, I_MUTEX_CHILD
);
3003 p
= d_ancestor(p1
, p2
);
3005 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
3006 inode_lock_nested(p2
->d_inode
, I_MUTEX_CHILD
);
3010 inode_lock_nested(p1
->d_inode
, I_MUTEX_PARENT
);
3011 inode_lock_nested(p2
->d_inode
, I_MUTEX_PARENT2
);
3014 EXPORT_SYMBOL(lock_rename
);
3016 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
3018 inode_unlock(p1
->d_inode
);
3020 inode_unlock(p2
->d_inode
);
3021 mutex_unlock(&p1
->d_sb
->s_vfs_rename_mutex
);
3024 EXPORT_SYMBOL(unlock_rename
);
3027 * mode_strip_umask - handle vfs umask stripping
3028 * @dir: parent directory of the new inode
3029 * @mode: mode of the new inode to be created in @dir
3031 * Umask stripping depends on whether or not the filesystem supports POSIX
3032 * ACLs. If the filesystem doesn't support it umask stripping is done directly
3033 * in here. If the filesystem does support POSIX ACLs umask stripping is
3034 * deferred until the filesystem calls posix_acl_create().
3038 static inline umode_t
mode_strip_umask(const struct inode
*dir
, umode_t mode
)
3040 if (!IS_POSIXACL(dir
))
3041 mode
&= ~current_umask();
3046 * vfs_prepare_mode - prepare the mode to be used for a new inode
3047 * @mnt_userns: user namespace of the mount the inode was found from
3048 * @dir: parent directory of the new inode
3049 * @mode: mode of the new inode
3050 * @mask_perms: allowed permission by the vfs
3051 * @type: type of file to be created
3053 * This helper consolidates and enforces vfs restrictions on the @mode of a new
3054 * object to be created.
3056 * Umask stripping depends on whether the filesystem supports POSIX ACLs (see
3057 * the kernel documentation for mode_strip_umask()). Moving umask stripping
3058 * after setgid stripping allows the same ordering for both non-POSIX ACL and
3059 * POSIX ACL supporting filesystems.
3061 * Note that it's currently valid for @type to be 0 if a directory is created.
3062 * Filesystems raise that flag individually and we need to check whether each
3063 * filesystem can deal with receiving S_IFDIR from the vfs before we enforce a
3066 * Returns: mode to be passed to the filesystem
3068 static inline umode_t
vfs_prepare_mode(struct user_namespace
*mnt_userns
,
3069 const struct inode
*dir
, umode_t mode
,
3070 umode_t mask_perms
, umode_t type
)
3072 mode
= mode_strip_sgid(mnt_userns
, dir
, mode
);
3073 mode
= mode_strip_umask(dir
, mode
);
3076 * Apply the vfs mandated allowed permission mask and set the type of
3077 * file to be created before we call into the filesystem.
3079 mode
&= (mask_perms
& ~S_IFMT
);
3080 mode
|= (type
& S_IFMT
);
3086 * vfs_create - create new file
3087 * @mnt_userns: user namespace of the mount the inode was found from
3088 * @dir: inode of @dentry
3089 * @dentry: pointer to dentry of the base directory
3090 * @mode: mode of the new file
3091 * @want_excl: whether the file must not yet exist
3093 * Create a new file.
3095 * If the inode has been found through an idmapped mount the user namespace of
3096 * the vfsmount must be passed through @mnt_userns. This function will then take
3097 * care to map the inode according to @mnt_userns before checking permissions.
3098 * On non-idmapped mounts or if permission checking is to be performed on the
3099 * raw inode simply passs init_user_ns.
3101 int vfs_create(struct user_namespace
*mnt_userns
, struct inode
*dir
,
3102 struct dentry
*dentry
, umode_t mode
, bool want_excl
)
3104 int error
= may_create(mnt_userns
, dir
, dentry
);
3108 if (!dir
->i_op
->create
)
3109 return -EACCES
; /* shouldn't it be ENOSYS? */
3111 mode
= vfs_prepare_mode(mnt_userns
, dir
, mode
, S_IALLUGO
, S_IFREG
);
3112 error
= security_inode_create(dir
, dentry
, mode
);
3115 error
= dir
->i_op
->create(mnt_userns
, dir
, dentry
, mode
, want_excl
);
3117 fsnotify_create(dir
, dentry
);
3120 EXPORT_SYMBOL(vfs_create
);
3122 int vfs_mkobj(struct dentry
*dentry
, umode_t mode
,
3123 int (*f
)(struct dentry
*, umode_t
, void *),
3126 struct inode
*dir
= dentry
->d_parent
->d_inode
;
3127 int error
= may_create(&init_user_ns
, dir
, dentry
);
3133 error
= security_inode_create(dir
, dentry
, mode
);
3136 error
= f(dentry
, mode
, arg
);
3138 fsnotify_create(dir
, dentry
);
3141 EXPORT_SYMBOL(vfs_mkobj
);
3143 bool may_open_dev(const struct path
*path
)
3145 return !(path
->mnt
->mnt_flags
& MNT_NODEV
) &&
3146 !(path
->mnt
->mnt_sb
->s_iflags
& SB_I_NODEV
);
3149 static int may_open(struct user_namespace
*mnt_userns
, const struct path
*path
,
3150 int acc_mode
, int flag
)
3152 struct dentry
*dentry
= path
->dentry
;
3153 struct inode
*inode
= dentry
->d_inode
;
3159 switch (inode
->i_mode
& S_IFMT
) {
3163 if (acc_mode
& MAY_WRITE
)
3165 if (acc_mode
& MAY_EXEC
)
3170 if (!may_open_dev(path
))
3175 if (acc_mode
& MAY_EXEC
)
3180 if ((acc_mode
& MAY_EXEC
) && path_noexec(path
))
3185 error
= inode_permission(mnt_userns
, inode
, MAY_OPEN
| acc_mode
);
3190 * An append-only file must be opened in append mode for writing.
3192 if (IS_APPEND(inode
)) {
3193 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
3199 /* O_NOATIME can only be set by the owner or superuser */
3200 if (flag
& O_NOATIME
&& !inode_owner_or_capable(mnt_userns
, inode
))
3206 static int handle_truncate(struct user_namespace
*mnt_userns
, struct file
*filp
)
3208 const struct path
*path
= &filp
->f_path
;
3209 struct inode
*inode
= path
->dentry
->d_inode
;
3210 int error
= get_write_access(inode
);
3214 error
= security_file_truncate(filp
);
3216 error
= do_truncate(mnt_userns
, path
->dentry
, 0,
3217 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
3220 put_write_access(inode
);
3224 static inline int open_to_namei_flags(int flag
)
3226 if ((flag
& O_ACCMODE
) == 3)
3231 static int may_o_create(struct user_namespace
*mnt_userns
,
3232 const struct path
*dir
, struct dentry
*dentry
,
3235 int error
= security_path_mknod(dir
, dentry
, mode
, 0);
3239 if (!fsuidgid_has_mapping(dir
->dentry
->d_sb
, mnt_userns
))
3242 error
= inode_permission(mnt_userns
, dir
->dentry
->d_inode
,
3243 MAY_WRITE
| MAY_EXEC
);
3247 return security_inode_create(dir
->dentry
->d_inode
, dentry
, mode
);
3251 * Attempt to atomically look up, create and open a file from a negative
3254 * Returns 0 if successful. The file will have been created and attached to
3255 * @file by the filesystem calling finish_open().
3257 * If the file was looked up only or didn't need creating, FMODE_OPENED won't
3258 * be set. The caller will need to perform the open themselves. @path will
3259 * have been updated to point to the new dentry. This may be negative.
3261 * Returns an error code otherwise.
3263 static struct dentry
*atomic_open(struct nameidata
*nd
, struct dentry
*dentry
,
3265 int open_flag
, umode_t mode
)
3267 struct dentry
*const DENTRY_NOT_SET
= (void *) -1UL;
3268 struct inode
*dir
= nd
->path
.dentry
->d_inode
;
3271 if (nd
->flags
& LOOKUP_DIRECTORY
)
3272 open_flag
|= O_DIRECTORY
;
3274 file
->f_path
.dentry
= DENTRY_NOT_SET
;
3275 file
->f_path
.mnt
= nd
->path
.mnt
;
3276 error
= dir
->i_op
->atomic_open(dir
, dentry
, file
,
3277 open_to_namei_flags(open_flag
), mode
);
3278 d_lookup_done(dentry
);
3280 if (file
->f_mode
& FMODE_OPENED
) {
3281 if (unlikely(dentry
!= file
->f_path
.dentry
)) {
3283 dentry
= dget(file
->f_path
.dentry
);
3285 } else if (WARN_ON(file
->f_path
.dentry
== DENTRY_NOT_SET
)) {
3288 if (file
->f_path
.dentry
) {
3290 dentry
= file
->f_path
.dentry
;
3292 if (unlikely(d_is_negative(dentry
)))
3298 dentry
= ERR_PTR(error
);
3304 * Look up and maybe create and open the last component.
3306 * Must be called with parent locked (exclusive in O_CREAT case).
3308 * Returns 0 on success, that is, if
3309 * the file was successfully atomically created (if necessary) and opened, or
3310 * the file was not completely opened at this time, though lookups and
3311 * creations were performed.
3312 * These case are distinguished by presence of FMODE_OPENED on file->f_mode.
3313 * In the latter case dentry returned in @path might be negative if O_CREAT
3314 * hadn't been specified.
3316 * An error code is returned on failure.
3318 static struct dentry
*lookup_open(struct nameidata
*nd
, struct file
*file
,
3319 const struct open_flags
*op
,
3322 struct user_namespace
*mnt_userns
;
3323 struct dentry
*dir
= nd
->path
.dentry
;
3324 struct inode
*dir_inode
= dir
->d_inode
;
3325 int open_flag
= op
->open_flag
;
3326 struct dentry
*dentry
;
3327 int error
, create_error
= 0;
3328 umode_t mode
= op
->mode
;
3329 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq
);
3331 if (unlikely(IS_DEADDIR(dir_inode
)))
3332 return ERR_PTR(-ENOENT
);
3334 file
->f_mode
&= ~FMODE_CREATED
;
3335 dentry
= d_lookup(dir
, &nd
->last
);
3338 dentry
= d_alloc_parallel(dir
, &nd
->last
, &wq
);
3342 if (d_in_lookup(dentry
))
3345 error
= d_revalidate(dentry
, nd
->flags
);
3346 if (likely(error
> 0))
3350 d_invalidate(dentry
);
3354 if (dentry
->d_inode
) {
3355 /* Cached positive dentry: will open in f_op->open */
3360 * Checking write permission is tricky, bacuse we don't know if we are
3361 * going to actually need it: O_CREAT opens should work as long as the
3362 * file exists. But checking existence breaks atomicity. The trick is
3363 * to check access and if not granted clear O_CREAT from the flags.
3365 * Another problem is returing the "right" error value (e.g. for an
3366 * O_EXCL open we want to return EEXIST not EROFS).
3368 if (unlikely(!got_write
))
3369 open_flag
&= ~O_TRUNC
;
3370 mnt_userns
= mnt_user_ns(nd
->path
.mnt
);
3371 if (open_flag
& O_CREAT
) {
3372 if (open_flag
& O_EXCL
)
3373 open_flag
&= ~O_TRUNC
;
3374 mode
= vfs_prepare_mode(mnt_userns
, dir
->d_inode
, mode
, mode
, mode
);
3375 if (likely(got_write
))
3376 create_error
= may_o_create(mnt_userns
, &nd
->path
,
3379 create_error
= -EROFS
;
3382 open_flag
&= ~O_CREAT
;
3383 if (dir_inode
->i_op
->atomic_open
) {
3384 dentry
= atomic_open(nd
, dentry
, file
, open_flag
, mode
);
3385 if (unlikely(create_error
) && dentry
== ERR_PTR(-ENOENT
))
3386 dentry
= ERR_PTR(create_error
);
3390 if (d_in_lookup(dentry
)) {
3391 struct dentry
*res
= dir_inode
->i_op
->lookup(dir_inode
, dentry
,
3393 d_lookup_done(dentry
);
3394 if (unlikely(res
)) {
3396 error
= PTR_ERR(res
);
3404 /* Negative dentry, just create the file */
3405 if (!dentry
->d_inode
&& (open_flag
& O_CREAT
)) {
3406 file
->f_mode
|= FMODE_CREATED
;
3407 audit_inode_child(dir_inode
, dentry
, AUDIT_TYPE_CHILD_CREATE
);
3408 if (!dir_inode
->i_op
->create
) {
3413 error
= dir_inode
->i_op
->create(mnt_userns
, dir_inode
, dentry
,
3414 mode
, open_flag
& O_EXCL
);
3418 if (unlikely(create_error
) && !dentry
->d_inode
) {
3419 error
= create_error
;
3426 return ERR_PTR(error
);
3429 static const char *open_last_lookups(struct nameidata
*nd
,
3430 struct file
*file
, const struct open_flags
*op
)
3432 struct dentry
*dir
= nd
->path
.dentry
;
3433 int open_flag
= op
->open_flag
;
3434 bool got_write
= false;
3435 struct dentry
*dentry
;
3438 nd
->flags
|= op
->intent
;
3440 if (nd
->last_type
!= LAST_NORM
) {
3443 return handle_dots(nd
, nd
->last_type
);
3446 if (!(open_flag
& O_CREAT
)) {
3447 if (nd
->last
.name
[nd
->last
.len
])
3448 nd
->flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
3449 /* we _can_ be in RCU mode here */
3450 dentry
= lookup_fast(nd
);
3452 return ERR_CAST(dentry
);
3456 BUG_ON(nd
->flags
& LOOKUP_RCU
);
3458 /* create side of things */
3459 if (nd
->flags
& LOOKUP_RCU
) {
3460 if (!try_to_unlazy(nd
))
3461 return ERR_PTR(-ECHILD
);
3463 audit_inode(nd
->name
, dir
, AUDIT_INODE_PARENT
);
3464 /* trailing slashes? */
3465 if (unlikely(nd
->last
.name
[nd
->last
.len
]))
3466 return ERR_PTR(-EISDIR
);
3469 if (open_flag
& (O_CREAT
| O_TRUNC
| O_WRONLY
| O_RDWR
)) {
3470 got_write
= !mnt_want_write(nd
->path
.mnt
);
3472 * do _not_ fail yet - we might not need that or fail with
3473 * a different error; let lookup_open() decide; we'll be
3474 * dropping this one anyway.
3477 if (open_flag
& O_CREAT
)
3478 inode_lock(dir
->d_inode
);
3480 inode_lock_shared(dir
->d_inode
);
3481 dentry
= lookup_open(nd
, file
, op
, got_write
);
3482 if (!IS_ERR(dentry
) && (file
->f_mode
& FMODE_CREATED
))
3483 fsnotify_create(dir
->d_inode
, dentry
);
3484 if (open_flag
& O_CREAT
)
3485 inode_unlock(dir
->d_inode
);
3487 inode_unlock_shared(dir
->d_inode
);
3490 mnt_drop_write(nd
->path
.mnt
);
3493 return ERR_CAST(dentry
);
3495 if (file
->f_mode
& (FMODE_OPENED
| FMODE_CREATED
)) {
3496 dput(nd
->path
.dentry
);
3497 nd
->path
.dentry
= dentry
;
3504 res
= step_into(nd
, WALK_TRAILING
, dentry
);
3506 nd
->flags
&= ~(LOOKUP_OPEN
|LOOKUP_CREATE
|LOOKUP_EXCL
);
3511 * Handle the last step of open()
3513 static int do_open(struct nameidata
*nd
,
3514 struct file
*file
, const struct open_flags
*op
)
3516 struct user_namespace
*mnt_userns
;
3517 int open_flag
= op
->open_flag
;
3522 if (!(file
->f_mode
& (FMODE_OPENED
| FMODE_CREATED
))) {
3523 error
= complete_walk(nd
);
3527 if (!(file
->f_mode
& FMODE_CREATED
))
3528 audit_inode(nd
->name
, nd
->path
.dentry
, 0);
3529 mnt_userns
= mnt_user_ns(nd
->path
.mnt
);
3530 if (open_flag
& O_CREAT
) {
3531 if ((open_flag
& O_EXCL
) && !(file
->f_mode
& FMODE_CREATED
))
3533 if (d_is_dir(nd
->path
.dentry
))
3535 error
= may_create_in_sticky(mnt_userns
, nd
,
3536 d_backing_inode(nd
->path
.dentry
));
3537 if (unlikely(error
))
3540 if ((nd
->flags
& LOOKUP_DIRECTORY
) && !d_can_lookup(nd
->path
.dentry
))
3543 do_truncate
= false;
3544 acc_mode
= op
->acc_mode
;
3545 if (file
->f_mode
& FMODE_CREATED
) {
3546 /* Don't check for write permission, don't truncate */
3547 open_flag
&= ~O_TRUNC
;
3549 } else if (d_is_reg(nd
->path
.dentry
) && open_flag
& O_TRUNC
) {
3550 error
= mnt_want_write(nd
->path
.mnt
);
3555 error
= may_open(mnt_userns
, &nd
->path
, acc_mode
, open_flag
);
3556 if (!error
&& !(file
->f_mode
& FMODE_OPENED
))
3557 error
= vfs_open(&nd
->path
, file
);
3559 error
= ima_file_check(file
, op
->acc_mode
);
3560 if (!error
&& do_truncate
)
3561 error
= handle_truncate(mnt_userns
, file
);
3562 if (unlikely(error
> 0)) {
3567 mnt_drop_write(nd
->path
.mnt
);
3572 * vfs_tmpfile - create tmpfile
3573 * @mnt_userns: user namespace of the mount the inode was found from
3574 * @dentry: pointer to dentry of the base directory
3575 * @mode: mode of the new tmpfile
3578 * Create a temporary file.
3580 * If the inode has been found through an idmapped mount the user namespace of
3581 * the vfsmount must be passed through @mnt_userns. This function will then take
3582 * care to map the inode according to @mnt_userns before checking permissions.
3583 * On non-idmapped mounts or if permission checking is to be performed on the
3584 * raw inode simply passs init_user_ns.
3586 static int vfs_tmpfile(struct user_namespace
*mnt_userns
,
3587 const struct path
*parentpath
,
3588 struct file
*file
, umode_t mode
)
3590 struct dentry
*child
;
3591 struct inode
*dir
= d_inode(parentpath
->dentry
);
3592 struct inode
*inode
;
3594 int open_flag
= file
->f_flags
;
3596 /* we want directory to be writable */
3597 error
= inode_permission(mnt_userns
, dir
, MAY_WRITE
| MAY_EXEC
);
3600 if (!dir
->i_op
->tmpfile
)
3602 child
= d_alloc(parentpath
->dentry
, &slash_name
);
3603 if (unlikely(!child
))
3605 file
->f_path
.mnt
= parentpath
->mnt
;
3606 file
->f_path
.dentry
= child
;
3607 mode
= vfs_prepare_mode(mnt_userns
, dir
, mode
, mode
, mode
);
3608 error
= dir
->i_op
->tmpfile(mnt_userns
, dir
, file
, mode
);
3612 /* Don't check for other permissions, the inode was just created */
3613 error
= may_open(mnt_userns
, &file
->f_path
, 0, file
->f_flags
);
3616 inode
= file_inode(file
);
3617 if (!(open_flag
& O_EXCL
)) {
3618 spin_lock(&inode
->i_lock
);
3619 inode
->i_state
|= I_LINKABLE
;
3620 spin_unlock(&inode
->i_lock
);
3622 ima_post_create_tmpfile(mnt_userns
, inode
);
3627 * vfs_tmpfile_open - open a tmpfile for kernel internal use
3628 * @mnt_userns: user namespace of the mount the inode was found from
3629 * @parentpath: path of the base directory
3630 * @mode: mode of the new tmpfile
3632 * @cred: credentials for open
3634 * Create and open a temporary file. The file is not accounted in nr_files,
3635 * hence this is only for kernel internal use, and must not be installed into
3636 * file tables or such.
3638 struct file
*vfs_tmpfile_open(struct user_namespace
*mnt_userns
,
3639 const struct path
*parentpath
,
3640 umode_t mode
, int open_flag
, const struct cred
*cred
)
3645 file
= alloc_empty_file_noaccount(open_flag
, cred
);
3646 if (!IS_ERR(file
)) {
3647 error
= vfs_tmpfile(mnt_userns
, parentpath
, file
, mode
);
3650 file
= ERR_PTR(error
);
3655 EXPORT_SYMBOL(vfs_tmpfile_open
);
3657 static int do_tmpfile(struct nameidata
*nd
, unsigned flags
,
3658 const struct open_flags
*op
,
3661 struct user_namespace
*mnt_userns
;
3663 int error
= path_lookupat(nd
, flags
| LOOKUP_DIRECTORY
, &path
);
3665 if (unlikely(error
))
3667 error
= mnt_want_write(path
.mnt
);
3668 if (unlikely(error
))
3670 mnt_userns
= mnt_user_ns(path
.mnt
);
3671 error
= vfs_tmpfile(mnt_userns
, &path
, file
, op
->mode
);
3674 audit_inode(nd
->name
, file
->f_path
.dentry
, 0);
3676 mnt_drop_write(path
.mnt
);
3682 static int do_o_path(struct nameidata
*nd
, unsigned flags
, struct file
*file
)
3685 int error
= path_lookupat(nd
, flags
, &path
);
3687 audit_inode(nd
->name
, path
.dentry
, 0);
3688 error
= vfs_open(&path
, file
);
3694 static struct file
*path_openat(struct nameidata
*nd
,
3695 const struct open_flags
*op
, unsigned flags
)
3700 file
= alloc_empty_file(op
->open_flag
, current_cred());
3704 if (unlikely(file
->f_flags
& __O_TMPFILE
)) {
3705 error
= do_tmpfile(nd
, flags
, op
, file
);
3706 } else if (unlikely(file
->f_flags
& O_PATH
)) {
3707 error
= do_o_path(nd
, flags
, file
);
3709 const char *s
= path_init(nd
, flags
);
3710 while (!(error
= link_path_walk(s
, nd
)) &&
3711 (s
= open_last_lookups(nd
, file
, op
)) != NULL
)
3714 error
= do_open(nd
, file
, op
);
3717 if (likely(!error
)) {
3718 if (likely(file
->f_mode
& FMODE_OPENED
))
3724 if (error
== -EOPENSTALE
) {
3725 if (flags
& LOOKUP_RCU
)
3730 return ERR_PTR(error
);
3733 struct file
*do_filp_open(int dfd
, struct filename
*pathname
,
3734 const struct open_flags
*op
)
3736 struct nameidata nd
;
3737 int flags
= op
->lookup_flags
;
3740 set_nameidata(&nd
, dfd
, pathname
, NULL
);
3741 filp
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3742 if (unlikely(filp
== ERR_PTR(-ECHILD
)))
3743 filp
= path_openat(&nd
, op
, flags
);
3744 if (unlikely(filp
== ERR_PTR(-ESTALE
)))
3745 filp
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3746 restore_nameidata();
3750 struct file
*do_file_open_root(const struct path
*root
,
3751 const char *name
, const struct open_flags
*op
)
3753 struct nameidata nd
;
3755 struct filename
*filename
;
3756 int flags
= op
->lookup_flags
;
3758 if (d_is_symlink(root
->dentry
) && op
->intent
& LOOKUP_OPEN
)
3759 return ERR_PTR(-ELOOP
);
3761 filename
= getname_kernel(name
);
3762 if (IS_ERR(filename
))
3763 return ERR_CAST(filename
);
3765 set_nameidata(&nd
, -1, filename
, root
);
3766 file
= path_openat(&nd
, op
, flags
| LOOKUP_RCU
);
3767 if (unlikely(file
== ERR_PTR(-ECHILD
)))
3768 file
= path_openat(&nd
, op
, flags
);
3769 if (unlikely(file
== ERR_PTR(-ESTALE
)))
3770 file
= path_openat(&nd
, op
, flags
| LOOKUP_REVAL
);
3771 restore_nameidata();
3776 static struct dentry
*filename_create(int dfd
, struct filename
*name
,
3777 struct path
*path
, unsigned int lookup_flags
)
3779 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
3781 bool want_dir
= lookup_flags
& LOOKUP_DIRECTORY
;
3782 unsigned int reval_flag
= lookup_flags
& LOOKUP_REVAL
;
3783 unsigned int create_flags
= LOOKUP_CREATE
| LOOKUP_EXCL
;
3788 error
= filename_parentat(dfd
, name
, reval_flag
, path
, &last
, &type
);
3790 return ERR_PTR(error
);
3793 * Yucky last component or no last component at all?
3794 * (foo/., foo/.., /////)
3796 if (unlikely(type
!= LAST_NORM
))
3799 /* don't fail immediately if it's r/o, at least try to report other errors */
3800 err2
= mnt_want_write(path
->mnt
);
3802 * Do the final lookup. Suppress 'create' if there is a trailing
3803 * '/', and a directory wasn't requested.
3805 if (last
.name
[last
.len
] && !want_dir
)
3807 inode_lock_nested(path
->dentry
->d_inode
, I_MUTEX_PARENT
);
3808 dentry
= __lookup_hash(&last
, path
->dentry
, reval_flag
| create_flags
);
3813 if (d_is_positive(dentry
))
3817 * Special case - lookup gave negative, but... we had foo/bar/
3818 * From the vfs_mknod() POV we just have a negative dentry -
3819 * all is fine. Let's be bastards - you had / on the end, you've
3820 * been asking for (non-existent) directory. -ENOENT for you.
3822 if (unlikely(!create_flags
)) {
3826 if (unlikely(err2
)) {
3833 dentry
= ERR_PTR(error
);
3835 inode_unlock(path
->dentry
->d_inode
);
3837 mnt_drop_write(path
->mnt
);
3843 struct dentry
*kern_path_create(int dfd
, const char *pathname
,
3844 struct path
*path
, unsigned int lookup_flags
)
3846 struct filename
*filename
= getname_kernel(pathname
);
3847 struct dentry
*res
= filename_create(dfd
, filename
, path
, lookup_flags
);
3852 EXPORT_SYMBOL(kern_path_create
);
3854 void done_path_create(struct path
*path
, struct dentry
*dentry
)
3857 inode_unlock(path
->dentry
->d_inode
);
3858 mnt_drop_write(path
->mnt
);
3861 EXPORT_SYMBOL(done_path_create
);
3863 inline struct dentry
*user_path_create(int dfd
, const char __user
*pathname
,
3864 struct path
*path
, unsigned int lookup_flags
)
3866 struct filename
*filename
= getname(pathname
);
3867 struct dentry
*res
= filename_create(dfd
, filename
, path
, lookup_flags
);
3872 EXPORT_SYMBOL(user_path_create
);
3875 * vfs_mknod - create device node or file
3876 * @mnt_userns: user namespace of the mount the inode was found from
3877 * @dir: inode of @dentry
3878 * @dentry: pointer to dentry of the base directory
3879 * @mode: mode of the new device node or file
3880 * @dev: device number of device to create
3882 * Create a device node or file.
3884 * If the inode has been found through an idmapped mount the user namespace of
3885 * the vfsmount must be passed through @mnt_userns. This function will then take
3886 * care to map the inode according to @mnt_userns before checking permissions.
3887 * On non-idmapped mounts or if permission checking is to be performed on the
3888 * raw inode simply passs init_user_ns.
3890 int vfs_mknod(struct user_namespace
*mnt_userns
, struct inode
*dir
,
3891 struct dentry
*dentry
, umode_t mode
, dev_t dev
)
3893 bool is_whiteout
= S_ISCHR(mode
) && dev
== WHITEOUT_DEV
;
3894 int error
= may_create(mnt_userns
, dir
, dentry
);
3899 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !is_whiteout
&&
3900 !capable(CAP_MKNOD
))
3903 if (!dir
->i_op
->mknod
)
3906 mode
= vfs_prepare_mode(mnt_userns
, dir
, mode
, mode
, mode
);
3907 error
= devcgroup_inode_mknod(mode
, dev
);
3911 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
3915 error
= dir
->i_op
->mknod(mnt_userns
, dir
, dentry
, mode
, dev
);
3917 fsnotify_create(dir
, dentry
);
3920 EXPORT_SYMBOL(vfs_mknod
);
3922 static int may_mknod(umode_t mode
)
3924 switch (mode
& S_IFMT
) {
3930 case 0: /* zero mode translates to S_IFREG */
3939 static int do_mknodat(int dfd
, struct filename
*name
, umode_t mode
,
3942 struct user_namespace
*mnt_userns
;
3943 struct dentry
*dentry
;
3946 unsigned int lookup_flags
= 0;
3948 error
= may_mknod(mode
);
3952 dentry
= filename_create(dfd
, name
, &path
, lookup_flags
);
3953 error
= PTR_ERR(dentry
);
3957 error
= security_path_mknod(&path
, dentry
,
3958 mode_strip_umask(path
.dentry
->d_inode
, mode
), dev
);
3962 mnt_userns
= mnt_user_ns(path
.mnt
);
3963 switch (mode
& S_IFMT
) {
3964 case 0: case S_IFREG
:
3965 error
= vfs_create(mnt_userns
, path
.dentry
->d_inode
,
3966 dentry
, mode
, true);
3968 ima_post_path_mknod(mnt_userns
, dentry
);
3970 case S_IFCHR
: case S_IFBLK
:
3971 error
= vfs_mknod(mnt_userns
, path
.dentry
->d_inode
,
3972 dentry
, mode
, new_decode_dev(dev
));
3974 case S_IFIFO
: case S_IFSOCK
:
3975 error
= vfs_mknod(mnt_userns
, path
.dentry
->d_inode
,
3980 done_path_create(&path
, dentry
);
3981 if (retry_estale(error
, lookup_flags
)) {
3982 lookup_flags
|= LOOKUP_REVAL
;
3990 SYSCALL_DEFINE4(mknodat
, int, dfd
, const char __user
*, filename
, umode_t
, mode
,
3993 return do_mknodat(dfd
, getname(filename
), mode
, dev
);
3996 SYSCALL_DEFINE3(mknod
, const char __user
*, filename
, umode_t
, mode
, unsigned, dev
)
3998 return do_mknodat(AT_FDCWD
, getname(filename
), mode
, dev
);
4002 * vfs_mkdir - create directory
4003 * @mnt_userns: user namespace of the mount the inode was found from
4004 * @dir: inode of @dentry
4005 * @dentry: pointer to dentry of the base directory
4006 * @mode: mode of the new directory
4008 * Create a directory.
4010 * If the inode has been found through an idmapped mount the user namespace of
4011 * the vfsmount must be passed through @mnt_userns. This function will then take
4012 * care to map the inode according to @mnt_userns before checking permissions.
4013 * On non-idmapped mounts or if permission checking is to be performed on the
4014 * raw inode simply passs init_user_ns.
4016 int vfs_mkdir(struct user_namespace
*mnt_userns
, struct inode
*dir
,
4017 struct dentry
*dentry
, umode_t mode
)
4019 int error
= may_create(mnt_userns
, dir
, dentry
);
4020 unsigned max_links
= dir
->i_sb
->s_max_links
;
4025 if (!dir
->i_op
->mkdir
)
4028 mode
= vfs_prepare_mode(mnt_userns
, dir
, mode
, S_IRWXUGO
| S_ISVTX
, 0);
4029 error
= security_inode_mkdir(dir
, dentry
, mode
);
4033 if (max_links
&& dir
->i_nlink
>= max_links
)
4036 error
= dir
->i_op
->mkdir(mnt_userns
, dir
, dentry
, mode
);
4038 fsnotify_mkdir(dir
, dentry
);
4041 EXPORT_SYMBOL(vfs_mkdir
);
4043 int do_mkdirat(int dfd
, struct filename
*name
, umode_t mode
)
4045 struct dentry
*dentry
;
4048 unsigned int lookup_flags
= LOOKUP_DIRECTORY
;
4051 dentry
= filename_create(dfd
, name
, &path
, lookup_flags
);
4052 error
= PTR_ERR(dentry
);
4056 error
= security_path_mkdir(&path
, dentry
,
4057 mode_strip_umask(path
.dentry
->d_inode
, mode
));
4059 struct user_namespace
*mnt_userns
;
4060 mnt_userns
= mnt_user_ns(path
.mnt
);
4061 error
= vfs_mkdir(mnt_userns
, path
.dentry
->d_inode
, dentry
,
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 * @mnt_userns: user namespace 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 user namespace of
4093 * the vfsmount must be passed through @mnt_userns. This function will then take
4094 * care to map the inode according to @mnt_userns before checking permissions.
4095 * On non-idmapped mounts or if permission checking is to be performed on the
4096 * raw inode simply passs init_user_ns.
4098 int vfs_rmdir(struct user_namespace
*mnt_userns
, struct inode
*dir
,
4099 struct dentry
*dentry
)
4101 int error
= may_delete(mnt_userns
, 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
)
4141 struct user_namespace
*mnt_userns
;
4143 struct dentry
*dentry
;
4147 unsigned int lookup_flags
= 0;
4149 error
= filename_parentat(dfd
, name
, lookup_flags
, &path
, &last
, &type
);
4165 error
= mnt_want_write(path
.mnt
);
4169 inode_lock_nested(path
.dentry
->d_inode
, I_MUTEX_PARENT
);
4170 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
4171 error
= PTR_ERR(dentry
);
4174 if (!dentry
->d_inode
) {
4178 error
= security_path_rmdir(&path
, dentry
);
4181 mnt_userns
= mnt_user_ns(path
.mnt
);
4182 error
= vfs_rmdir(mnt_userns
, path
.dentry
->d_inode
, dentry
);
4186 inode_unlock(path
.dentry
->d_inode
);
4187 mnt_drop_write(path
.mnt
);
4190 if (retry_estale(error
, lookup_flags
)) {
4191 lookup_flags
|= LOOKUP_REVAL
;
4199 SYSCALL_DEFINE1(rmdir
, const char __user
*, pathname
)
4201 return do_rmdir(AT_FDCWD
, getname(pathname
));
4205 * vfs_unlink - unlink a filesystem object
4206 * @mnt_userns: user namespace of the mount the inode was found from
4207 * @dir: parent directory
4209 * @delegated_inode: returns victim inode, if the inode is delegated.
4211 * The caller must hold dir->i_mutex.
4213 * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
4214 * return a reference to the inode in delegated_inode. The caller
4215 * should then break the delegation on that inode and retry. Because
4216 * breaking a delegation may take a long time, the caller should drop
4217 * dir->i_mutex before doing so.
4219 * Alternatively, a caller may pass NULL for delegated_inode. This may
4220 * be appropriate for callers that expect the underlying filesystem not
4221 * to be NFS exported.
4223 * If the inode has been found through an idmapped mount the user namespace of
4224 * the vfsmount must be passed through @mnt_userns. This function will then take
4225 * care to map the inode according to @mnt_userns before checking permissions.
4226 * On non-idmapped mounts or if permission checking is to be performed on the
4227 * raw inode simply passs init_user_ns.
4229 int vfs_unlink(struct user_namespace
*mnt_userns
, struct inode
*dir
,
4230 struct dentry
*dentry
, struct inode
**delegated_inode
)
4232 struct inode
*target
= dentry
->d_inode
;
4233 int error
= may_delete(mnt_userns
, dir
, dentry
, 0);
4238 if (!dir
->i_op
->unlink
)
4242 if (IS_SWAPFILE(target
))
4244 else if (is_local_mountpoint(dentry
))
4247 error
= security_inode_unlink(dir
, dentry
);
4249 error
= try_break_deleg(target
, delegated_inode
);
4252 error
= dir
->i_op
->unlink(dir
, dentry
);
4255 detach_mounts(dentry
);
4260 inode_unlock(target
);
4262 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
4263 if (!error
&& dentry
->d_flags
& DCACHE_NFSFS_RENAMED
) {
4264 fsnotify_unlink(dir
, dentry
);
4265 } else if (!error
) {
4266 fsnotify_link_count(target
);
4267 d_delete_notify(dir
, dentry
);
4272 EXPORT_SYMBOL(vfs_unlink
);
4275 * Make sure that the actual truncation of the file will occur outside its
4276 * directory's i_mutex. Truncate can take a long time if there is a lot of
4277 * writeout happening, and we don't want to prevent access to the directory
4278 * while waiting on the I/O.
4280 int do_unlinkat(int dfd
, struct filename
*name
)
4283 struct dentry
*dentry
;
4287 struct inode
*inode
= NULL
;
4288 struct inode
*delegated_inode
= NULL
;
4289 unsigned int lookup_flags
= 0;
4291 error
= filename_parentat(dfd
, name
, lookup_flags
, &path
, &last
, &type
);
4296 if (type
!= LAST_NORM
)
4299 error
= mnt_want_write(path
.mnt
);
4303 inode_lock_nested(path
.dentry
->d_inode
, I_MUTEX_PARENT
);
4304 dentry
= __lookup_hash(&last
, path
.dentry
, lookup_flags
);
4305 error
= PTR_ERR(dentry
);
4306 if (!IS_ERR(dentry
)) {
4307 struct user_namespace
*mnt_userns
;
4309 /* Why not before? Because we want correct error value */
4310 if (last
.name
[last
.len
])
4312 inode
= dentry
->d_inode
;
4313 if (d_is_negative(dentry
))
4316 error
= security_path_unlink(&path
, dentry
);
4319 mnt_userns
= mnt_user_ns(path
.mnt
);
4320 error
= vfs_unlink(mnt_userns
, path
.dentry
->d_inode
, dentry
,
4325 inode_unlock(path
.dentry
->d_inode
);
4327 iput(inode
); /* truncate the inode here */
4329 if (delegated_inode
) {
4330 error
= break_deleg_wait(&delegated_inode
);
4334 mnt_drop_write(path
.mnt
);
4337 if (retry_estale(error
, lookup_flags
)) {
4338 lookup_flags
|= LOOKUP_REVAL
;
4347 if (d_is_negative(dentry
))
4349 else if (d_is_dir(dentry
))
4356 SYSCALL_DEFINE3(unlinkat
, int, dfd
, const char __user
*, pathname
, int, flag
)
4358 if ((flag
& ~AT_REMOVEDIR
) != 0)
4361 if (flag
& AT_REMOVEDIR
)
4362 return do_rmdir(dfd
, getname(pathname
));
4363 return do_unlinkat(dfd
, getname(pathname
));
4366 SYSCALL_DEFINE1(unlink
, const char __user
*, pathname
)
4368 return do_unlinkat(AT_FDCWD
, getname(pathname
));
4372 * vfs_symlink - create symlink
4373 * @mnt_userns: user namespace of the mount the inode was found from
4374 * @dir: inode of @dentry
4375 * @dentry: pointer to dentry of the base directory
4376 * @oldname: name of the file to link to
4380 * If the inode has been found through an idmapped mount the user namespace of
4381 * the vfsmount must be passed through @mnt_userns. This function will then take
4382 * care to map the inode according to @mnt_userns before checking permissions.
4383 * On non-idmapped mounts or if permission checking is to be performed on the
4384 * raw inode simply passs init_user_ns.
4386 int vfs_symlink(struct user_namespace
*mnt_userns
, struct inode
*dir
,
4387 struct dentry
*dentry
, const char *oldname
)
4389 int error
= may_create(mnt_userns
, dir
, dentry
);
4394 if (!dir
->i_op
->symlink
)
4397 error
= security_inode_symlink(dir
, dentry
, oldname
);
4401 error
= dir
->i_op
->symlink(mnt_userns
, dir
, dentry
, oldname
);
4403 fsnotify_create(dir
, dentry
);
4406 EXPORT_SYMBOL(vfs_symlink
);
4408 int do_symlinkat(struct filename
*from
, int newdfd
, struct filename
*to
)
4411 struct dentry
*dentry
;
4413 unsigned int lookup_flags
= 0;
4416 error
= PTR_ERR(from
);
4420 dentry
= filename_create(newdfd
, to
, &path
, lookup_flags
);
4421 error
= PTR_ERR(dentry
);
4425 error
= security_path_symlink(&path
, dentry
, from
->name
);
4427 struct user_namespace
*mnt_userns
;
4429 mnt_userns
= mnt_user_ns(path
.mnt
);
4430 error
= vfs_symlink(mnt_userns
, path
.dentry
->d_inode
, dentry
,
4433 done_path_create(&path
, dentry
);
4434 if (retry_estale(error
, lookup_flags
)) {
4435 lookup_flags
|= LOOKUP_REVAL
;
4444 SYSCALL_DEFINE3(symlinkat
, const char __user
*, oldname
,
4445 int, newdfd
, const char __user
*, newname
)
4447 return do_symlinkat(getname(oldname
), newdfd
, getname(newname
));
4450 SYSCALL_DEFINE2(symlink
, const char __user
*, oldname
, const char __user
*, newname
)
4452 return do_symlinkat(getname(oldname
), AT_FDCWD
, getname(newname
));
4456 * vfs_link - create a new link
4457 * @old_dentry: object to be linked
4458 * @mnt_userns: the user namespace of the mount
4460 * @new_dentry: where to create the new link
4461 * @delegated_inode: returns inode needing a delegation break
4463 * The caller must hold dir->i_mutex
4465 * If vfs_link discovers a delegation on the to-be-linked file in need
4466 * of breaking, it will return -EWOULDBLOCK and return a reference to the
4467 * inode in delegated_inode. The caller should then break the delegation
4468 * and retry. Because breaking a delegation may take a long time, the
4469 * caller should drop the i_mutex before doing so.
4471 * Alternatively, a caller may pass NULL for delegated_inode. This may
4472 * be appropriate for callers that expect the underlying filesystem not
4473 * to be NFS exported.
4475 * If the inode has been found through an idmapped mount the user namespace of
4476 * the vfsmount must be passed through @mnt_userns. This function will then take
4477 * care to map the inode according to @mnt_userns before checking permissions.
4478 * On non-idmapped mounts or if permission checking is to be performed on the
4479 * raw inode simply passs init_user_ns.
4481 int vfs_link(struct dentry
*old_dentry
, struct user_namespace
*mnt_userns
,
4482 struct inode
*dir
, struct dentry
*new_dentry
,
4483 struct inode
**delegated_inode
)
4485 struct inode
*inode
= old_dentry
->d_inode
;
4486 unsigned max_links
= dir
->i_sb
->s_max_links
;
4492 error
= may_create(mnt_userns
, dir
, new_dentry
);
4496 if (dir
->i_sb
!= inode
->i_sb
)
4500 * A link to an append-only or immutable file cannot be created.
4502 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
4505 * Updating the link count will likely cause i_uid and i_gid to
4506 * be writen back improperly if their true value is unknown to
4509 if (HAS_UNMAPPED_ID(mnt_userns
, inode
))
4511 if (!dir
->i_op
->link
)
4513 if (S_ISDIR(inode
->i_mode
))
4516 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
4521 /* Make sure we don't allow creating hardlink to an unlinked file */
4522 if (inode
->i_nlink
== 0 && !(inode
->i_state
& I_LINKABLE
))
4524 else if (max_links
&& inode
->i_nlink
>= max_links
)
4527 error
= try_break_deleg(inode
, delegated_inode
);
4529 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
4532 if (!error
&& (inode
->i_state
& I_LINKABLE
)) {
4533 spin_lock(&inode
->i_lock
);
4534 inode
->i_state
&= ~I_LINKABLE
;
4535 spin_unlock(&inode
->i_lock
);
4537 inode_unlock(inode
);
4539 fsnotify_link(dir
, inode
, new_dentry
);
4542 EXPORT_SYMBOL(vfs_link
);
4545 * Hardlinks are often used in delicate situations. We avoid
4546 * security-related surprises by not following symlinks on the
4549 * We don't follow them on the oldname either to be compatible
4550 * with linux 2.0, and to avoid hard-linking to directories
4551 * and other special files. --ADM
4553 int do_linkat(int olddfd
, struct filename
*old
, int newdfd
,
4554 struct filename
*new, int flags
)
4556 struct user_namespace
*mnt_userns
;
4557 struct dentry
*new_dentry
;
4558 struct path old_path
, new_path
;
4559 struct inode
*delegated_inode
= NULL
;
4563 if ((flags
& ~(AT_SYMLINK_FOLLOW
| AT_EMPTY_PATH
)) != 0) {
4568 * To use null names we require CAP_DAC_READ_SEARCH
4569 * This ensures that not everyone will be able to create
4570 * handlink using the passed filedescriptor.
4572 if (flags
& AT_EMPTY_PATH
&& !capable(CAP_DAC_READ_SEARCH
)) {
4577 if (flags
& AT_SYMLINK_FOLLOW
)
4578 how
|= LOOKUP_FOLLOW
;
4580 error
= filename_lookup(olddfd
, old
, how
, &old_path
, NULL
);
4584 new_dentry
= filename_create(newdfd
, new, &new_path
,
4585 (how
& LOOKUP_REVAL
));
4586 error
= PTR_ERR(new_dentry
);
4587 if (IS_ERR(new_dentry
))
4591 if (old_path
.mnt
!= new_path
.mnt
)
4593 mnt_userns
= mnt_user_ns(new_path
.mnt
);
4594 error
= may_linkat(mnt_userns
, &old_path
);
4595 if (unlikely(error
))
4597 error
= security_path_link(old_path
.dentry
, &new_path
, new_dentry
);
4600 error
= vfs_link(old_path
.dentry
, mnt_userns
, new_path
.dentry
->d_inode
,
4601 new_dentry
, &delegated_inode
);
4603 done_path_create(&new_path
, new_dentry
);
4604 if (delegated_inode
) {
4605 error
= break_deleg_wait(&delegated_inode
);
4607 path_put(&old_path
);
4611 if (retry_estale(error
, how
)) {
4612 path_put(&old_path
);
4613 how
|= LOOKUP_REVAL
;
4617 path_put(&old_path
);
4625 SYSCALL_DEFINE5(linkat
, int, olddfd
, const char __user
*, oldname
,
4626 int, newdfd
, const char __user
*, newname
, int, flags
)
4628 return do_linkat(olddfd
, getname_uflags(oldname
, flags
),
4629 newdfd
, getname(newname
), flags
);
4632 SYSCALL_DEFINE2(link
, const char __user
*, oldname
, const char __user
*, newname
)
4634 return do_linkat(AT_FDCWD
, getname(oldname
), AT_FDCWD
, getname(newname
), 0);
4638 * vfs_rename - rename a filesystem object
4639 * @rd: pointer to &struct renamedata info
4641 * The caller must hold multiple mutexes--see lock_rename()).
4643 * If vfs_rename discovers a delegation in need of breaking at either
4644 * the source or destination, it will return -EWOULDBLOCK and return a
4645 * reference to the inode in delegated_inode. The caller should then
4646 * break the delegation and retry. Because breaking a delegation may
4647 * take a long time, the caller should drop all locks before doing
4650 * Alternatively, a caller may pass NULL for delegated_inode. This may
4651 * be appropriate for callers that expect the underlying filesystem not
4652 * to be NFS exported.
4654 * The worst of all namespace operations - renaming directory. "Perverted"
4655 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
4658 * a) we can get into loop creation.
4659 * b) race potential - two innocent renames can create a loop together.
4660 * That's where 4.4 screws up. Current fix: serialization on
4661 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
4663 * c) we have to lock _four_ objects - parents and victim (if it exists),
4664 * and source (if it is not a directory).
4665 * And that - after we got ->i_mutex on parents (until then we don't know
4666 * whether the target exists). Solution: try to be smart with locking
4667 * order for inodes. We rely on the fact that tree topology may change
4668 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
4669 * move will be locked. Thus we can rank directories by the tree
4670 * (ancestors first) and rank all non-directories after them.
4671 * That works since everybody except rename does "lock parent, lookup,
4672 * lock child" and rename is under ->s_vfs_rename_mutex.
4673 * HOWEVER, it relies on the assumption that any object with ->lookup()
4674 * has no more than 1 dentry. If "hybrid" objects will ever appear,
4675 * we'd better make sure that there's no link(2) for them.
4676 * d) conversion from fhandle to dentry may come in the wrong moment - when
4677 * we are removing the target. Solution: we will have to grab ->i_mutex
4678 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
4679 * ->i_mutex on parents, which works but leads to some truly excessive
4682 int vfs_rename(struct renamedata
*rd
)
4685 struct inode
*old_dir
= rd
->old_dir
, *new_dir
= rd
->new_dir
;
4686 struct dentry
*old_dentry
= rd
->old_dentry
;
4687 struct dentry
*new_dentry
= rd
->new_dentry
;
4688 struct inode
**delegated_inode
= rd
->delegated_inode
;
4689 unsigned int flags
= rd
->flags
;
4690 bool is_dir
= d_is_dir(old_dentry
);
4691 struct inode
*source
= old_dentry
->d_inode
;
4692 struct inode
*target
= new_dentry
->d_inode
;
4693 bool new_is_dir
= false;
4694 unsigned max_links
= new_dir
->i_sb
->s_max_links
;
4695 struct name_snapshot old_name
;
4697 if (source
== target
)
4700 error
= may_delete(rd
->old_mnt_userns
, old_dir
, old_dentry
, is_dir
);
4705 error
= may_create(rd
->new_mnt_userns
, new_dir
, new_dentry
);
4707 new_is_dir
= d_is_dir(new_dentry
);
4709 if (!(flags
& RENAME_EXCHANGE
))
4710 error
= may_delete(rd
->new_mnt_userns
, new_dir
,
4711 new_dentry
, is_dir
);
4713 error
= may_delete(rd
->new_mnt_userns
, new_dir
,
4714 new_dentry
, new_is_dir
);
4719 if (!old_dir
->i_op
->rename
)
4723 * If we are going to change the parent - check write permissions,
4724 * we'll need to flip '..'.
4726 if (new_dir
!= old_dir
) {
4728 error
= inode_permission(rd
->old_mnt_userns
, source
,
4733 if ((flags
& RENAME_EXCHANGE
) && new_is_dir
) {
4734 error
= inode_permission(rd
->new_mnt_userns
, target
,
4741 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
,
4746 take_dentry_name_snapshot(&old_name
, old_dentry
);
4748 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4749 lock_two_nondirectories(source
, target
);
4754 if (IS_SWAPFILE(source
) || (target
&& IS_SWAPFILE(target
)))
4758 if (is_local_mountpoint(old_dentry
) || is_local_mountpoint(new_dentry
))
4761 if (max_links
&& new_dir
!= old_dir
) {
4763 if (is_dir
&& !new_is_dir
&& new_dir
->i_nlink
>= max_links
)
4765 if ((flags
& RENAME_EXCHANGE
) && !is_dir
&& new_is_dir
&&
4766 old_dir
->i_nlink
>= max_links
)
4770 error
= try_break_deleg(source
, delegated_inode
);
4774 if (target
&& !new_is_dir
) {
4775 error
= try_break_deleg(target
, delegated_inode
);
4779 error
= old_dir
->i_op
->rename(rd
->new_mnt_userns
, old_dir
, old_dentry
,
4780 new_dir
, new_dentry
, flags
);
4784 if (!(flags
& RENAME_EXCHANGE
) && target
) {
4786 shrink_dcache_parent(new_dentry
);
4787 target
->i_flags
|= S_DEAD
;
4789 dont_mount(new_dentry
);
4790 detach_mounts(new_dentry
);
4792 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
)) {
4793 if (!(flags
& RENAME_EXCHANGE
))
4794 d_move(old_dentry
, new_dentry
);
4796 d_exchange(old_dentry
, new_dentry
);
4799 if (!is_dir
|| (flags
& RENAME_EXCHANGE
))
4800 unlock_two_nondirectories(source
, target
);
4802 inode_unlock(target
);
4805 fsnotify_move(old_dir
, new_dir
, &old_name
.name
, is_dir
,
4806 !(flags
& RENAME_EXCHANGE
) ? target
: NULL
, old_dentry
);
4807 if (flags
& RENAME_EXCHANGE
) {
4808 fsnotify_move(new_dir
, old_dir
, &old_dentry
->d_name
,
4809 new_is_dir
, NULL
, new_dentry
);
4812 release_dentry_name_snapshot(&old_name
);
4816 EXPORT_SYMBOL(vfs_rename
);
4818 int do_renameat2(int olddfd
, struct filename
*from
, int newdfd
,
4819 struct filename
*to
, unsigned int flags
)
4821 struct renamedata rd
;
4822 struct dentry
*old_dentry
, *new_dentry
;
4823 struct dentry
*trap
;
4824 struct path old_path
, new_path
;
4825 struct qstr old_last
, new_last
;
4826 int old_type
, new_type
;
4827 struct inode
*delegated_inode
= NULL
;
4828 unsigned int lookup_flags
= 0, target_flags
= LOOKUP_RENAME_TARGET
;
4829 bool should_retry
= false;
4830 int error
= -EINVAL
;
4832 if (flags
& ~(RENAME_NOREPLACE
| RENAME_EXCHANGE
| RENAME_WHITEOUT
))
4835 if ((flags
& (RENAME_NOREPLACE
| RENAME_WHITEOUT
)) &&
4836 (flags
& RENAME_EXCHANGE
))
4839 if (flags
& RENAME_EXCHANGE
)
4843 error
= filename_parentat(olddfd
, from
, lookup_flags
, &old_path
,
4844 &old_last
, &old_type
);
4848 error
= filename_parentat(newdfd
, to
, lookup_flags
, &new_path
, &new_last
,
4854 if (old_path
.mnt
!= new_path
.mnt
)
4858 if (old_type
!= LAST_NORM
)
4861 if (flags
& RENAME_NOREPLACE
)
4863 if (new_type
!= LAST_NORM
)
4866 error
= mnt_want_write(old_path
.mnt
);
4871 trap
= lock_rename(new_path
.dentry
, old_path
.dentry
);
4873 old_dentry
= __lookup_hash(&old_last
, old_path
.dentry
, lookup_flags
);
4874 error
= PTR_ERR(old_dentry
);
4875 if (IS_ERR(old_dentry
))
4877 /* source must exist */
4879 if (d_is_negative(old_dentry
))
4881 new_dentry
= __lookup_hash(&new_last
, new_path
.dentry
, lookup_flags
| target_flags
);
4882 error
= PTR_ERR(new_dentry
);
4883 if (IS_ERR(new_dentry
))
4886 if ((flags
& RENAME_NOREPLACE
) && d_is_positive(new_dentry
))
4888 if (flags
& RENAME_EXCHANGE
) {
4890 if (d_is_negative(new_dentry
))
4893 if (!d_is_dir(new_dentry
)) {
4895 if (new_last
.name
[new_last
.len
])
4899 /* unless the source is a directory trailing slashes give -ENOTDIR */
4900 if (!d_is_dir(old_dentry
)) {
4902 if (old_last
.name
[old_last
.len
])
4904 if (!(flags
& RENAME_EXCHANGE
) && new_last
.name
[new_last
.len
])
4907 /* source should not be ancestor of target */
4909 if (old_dentry
== trap
)
4911 /* target should not be an ancestor of source */
4912 if (!(flags
& RENAME_EXCHANGE
))
4914 if (new_dentry
== trap
)
4917 error
= security_path_rename(&old_path
, old_dentry
,
4918 &new_path
, new_dentry
, flags
);
4922 rd
.old_dir
= old_path
.dentry
->d_inode
;
4923 rd
.old_dentry
= old_dentry
;
4924 rd
.old_mnt_userns
= mnt_user_ns(old_path
.mnt
);
4925 rd
.new_dir
= new_path
.dentry
->d_inode
;
4926 rd
.new_dentry
= new_dentry
;
4927 rd
.new_mnt_userns
= mnt_user_ns(new_path
.mnt
);
4928 rd
.delegated_inode
= &delegated_inode
;
4930 error
= vfs_rename(&rd
);
4936 unlock_rename(new_path
.dentry
, old_path
.dentry
);
4937 if (delegated_inode
) {
4938 error
= break_deleg_wait(&delegated_inode
);
4942 mnt_drop_write(old_path
.mnt
);
4944 if (retry_estale(error
, lookup_flags
))
4945 should_retry
= true;
4946 path_put(&new_path
);
4948 path_put(&old_path
);
4950 should_retry
= false;
4951 lookup_flags
|= LOOKUP_REVAL
;
4960 SYSCALL_DEFINE5(renameat2
, int, olddfd
, const char __user
*, oldname
,
4961 int, newdfd
, const char __user
*, newname
, unsigned int, flags
)
4963 return do_renameat2(olddfd
, getname(oldname
), newdfd
, getname(newname
),
4967 SYSCALL_DEFINE4(renameat
, int, olddfd
, const char __user
*, oldname
,
4968 int, newdfd
, const char __user
*, newname
)
4970 return do_renameat2(olddfd
, getname(oldname
), newdfd
, getname(newname
),
4974 SYSCALL_DEFINE2(rename
, const char __user
*, oldname
, const char __user
*, newname
)
4976 return do_renameat2(AT_FDCWD
, getname(oldname
), AT_FDCWD
,
4977 getname(newname
), 0);
4980 int readlink_copy(char __user
*buffer
, int buflen
, const char *link
)
4982 int len
= PTR_ERR(link
);
4987 if (len
> (unsigned) buflen
)
4989 if (copy_to_user(buffer
, link
, len
))
4996 * vfs_readlink - copy symlink body into userspace buffer
4997 * @dentry: dentry on which to get symbolic link
4998 * @buffer: user memory pointer
4999 * @buflen: size of buffer
5001 * Does not touch atime. That's up to the caller if necessary
5003 * Does not call security hook.
5005 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
5007 struct inode
*inode
= d_inode(dentry
);
5008 DEFINE_DELAYED_CALL(done
);
5012 if (unlikely(!(inode
->i_opflags
& IOP_DEFAULT_READLINK
))) {
5013 if (unlikely(inode
->i_op
->readlink
))
5014 return inode
->i_op
->readlink(dentry
, buffer
, buflen
);
5016 if (!d_is_symlink(dentry
))
5019 spin_lock(&inode
->i_lock
);
5020 inode
->i_opflags
|= IOP_DEFAULT_READLINK
;
5021 spin_unlock(&inode
->i_lock
);
5024 link
= READ_ONCE(inode
->i_link
);
5026 link
= inode
->i_op
->get_link(dentry
, inode
, &done
);
5028 return PTR_ERR(link
);
5030 res
= readlink_copy(buffer
, buflen
, link
);
5031 do_delayed_call(&done
);
5034 EXPORT_SYMBOL(vfs_readlink
);
5037 * vfs_get_link - get symlink body
5038 * @dentry: dentry on which to get symbolic link
5039 * @done: caller needs to free returned data with this
5041 * Calls security hook and i_op->get_link() on the supplied inode.
5043 * It does not touch atime. That's up to the caller if necessary.
5045 * Does not work on "special" symlinks like /proc/$$/fd/N
5047 const char *vfs_get_link(struct dentry
*dentry
, struct delayed_call
*done
)
5049 const char *res
= ERR_PTR(-EINVAL
);
5050 struct inode
*inode
= d_inode(dentry
);
5052 if (d_is_symlink(dentry
)) {
5053 res
= ERR_PTR(security_inode_readlink(dentry
));
5055 res
= inode
->i_op
->get_link(dentry
, inode
, done
);
5059 EXPORT_SYMBOL(vfs_get_link
);
5061 /* get the link contents into pagecache */
5062 const char *page_get_link(struct dentry
*dentry
, struct inode
*inode
,
5063 struct delayed_call
*callback
)
5067 struct address_space
*mapping
= inode
->i_mapping
;
5070 page
= find_get_page(mapping
, 0);
5072 return ERR_PTR(-ECHILD
);
5073 if (!PageUptodate(page
)) {
5075 return ERR_PTR(-ECHILD
);
5078 page
= read_mapping_page(mapping
, 0, NULL
);
5082 set_delayed_call(callback
, page_put_link
, page
);
5083 BUG_ON(mapping_gfp_mask(mapping
) & __GFP_HIGHMEM
);
5084 kaddr
= page_address(page
);
5085 nd_terminate_link(kaddr
, inode
->i_size
, PAGE_SIZE
- 1);
5089 EXPORT_SYMBOL(page_get_link
);
5091 void page_put_link(void *arg
)
5095 EXPORT_SYMBOL(page_put_link
);
5097 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
5099 DEFINE_DELAYED_CALL(done
);
5100 int res
= readlink_copy(buffer
, buflen
,
5101 page_get_link(dentry
, d_inode(dentry
),
5103 do_delayed_call(&done
);
5106 EXPORT_SYMBOL(page_readlink
);
5108 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
5110 struct address_space
*mapping
= inode
->i_mapping
;
5111 const struct address_space_operations
*aops
= mapping
->a_ops
;
5112 bool nofs
= !mapping_gfp_constraint(mapping
, __GFP_FS
);
5114 void *fsdata
= NULL
;
5120 flags
= memalloc_nofs_save();
5121 err
= aops
->write_begin(NULL
, mapping
, 0, len
-1, &page
, &fsdata
);
5123 memalloc_nofs_restore(flags
);
5127 memcpy(page_address(page
), symname
, len
-1);
5129 err
= aops
->write_end(NULL
, mapping
, 0, len
-1, len
-1,
5136 mark_inode_dirty(inode
);
5141 EXPORT_SYMBOL(page_symlink
);
5143 const struct inode_operations page_symlink_inode_operations
= {
5144 .get_link
= page_get_link
,
5146 EXPORT_SYMBOL(page_symlink_inode_operations
);