1 // SPDX-License-Identifier: GPL-2.0-only
5 Extended attribute handling.
7 Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
8 Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
9 Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
12 #include <linux/slab.h>
13 #include <linux/file.h>
14 #include <linux/xattr.h>
15 #include <linux/mount.h>
16 #include <linux/namei.h>
17 #include <linux/security.h>
18 #include <linux/evm.h>
19 #include <linux/syscalls.h>
20 #include <linux/export.h>
21 #include <linux/fsnotify.h>
22 #include <linux/audit.h>
23 #include <linux/vmalloc.h>
24 #include <linux/posix_acl_xattr.h>
26 #include <linux/uaccess.h>
29 strcmp_prefix(const char *a
, const char *a_prefix
)
31 while (*a_prefix
&& *a
== *a_prefix
) {
35 return *a_prefix
? NULL
: a
;
39 * In order to implement different sets of xattr operations for each xattr
40 * prefix, a filesystem should create a null-terminated array of struct
41 * xattr_handler (one for each prefix) and hang a pointer to it off of the
42 * s_xattr field of the superblock.
44 #define for_each_xattr_handler(handlers, handler) \
46 for ((handler) = *(handlers)++; \
48 (handler) = *(handlers)++)
51 * Find the xattr_handler with the matching prefix.
53 static const struct xattr_handler
*
54 xattr_resolve_name(struct inode
*inode
, const char **name
)
56 const struct xattr_handler
**handlers
= inode
->i_sb
->s_xattr
;
57 const struct xattr_handler
*handler
;
59 if (!(inode
->i_opflags
& IOP_XATTR
)) {
60 if (unlikely(is_bad_inode(inode
)))
62 return ERR_PTR(-EOPNOTSUPP
);
64 for_each_xattr_handler(handlers
, handler
) {
67 n
= strcmp_prefix(*name
, xattr_prefix(handler
));
69 if (!handler
->prefix
^ !*n
) {
72 return ERR_PTR(-EINVAL
);
78 return ERR_PTR(-EOPNOTSUPP
);
82 * Check permissions for extended attribute access. This is a bit complicated
83 * because different namespaces have very different rules.
86 xattr_permission(struct user_namespace
*mnt_userns
, struct inode
*inode
,
87 const char *name
, int mask
)
90 * We can never set or remove an extended attribute on a read-only
91 * filesystem or on an immutable / append-only inode.
93 if (mask
& MAY_WRITE
) {
94 if (IS_IMMUTABLE(inode
) || IS_APPEND(inode
))
97 * Updating an xattr will likely cause i_uid and i_gid
98 * to be writen back improperly if their true value is
101 if (HAS_UNMAPPED_ID(mnt_userns
, inode
))
106 * No restriction for security.* and system.* from the VFS. Decision
107 * on these is left to the underlying filesystem / security module.
109 if (!strncmp(name
, XATTR_SECURITY_PREFIX
, XATTR_SECURITY_PREFIX_LEN
) ||
110 !strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
114 * The trusted.* namespace can only be accessed by privileged users.
116 if (!strncmp(name
, XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
)) {
117 if (!capable(CAP_SYS_ADMIN
))
118 return (mask
& MAY_WRITE
) ? -EPERM
: -ENODATA
;
123 * In the user.* namespace, only regular files and directories can have
124 * extended attributes. For sticky directories, only the owner and
125 * privileged users can write attributes.
127 if (!strncmp(name
, XATTR_USER_PREFIX
, XATTR_USER_PREFIX_LEN
)) {
128 if (!S_ISREG(inode
->i_mode
) && !S_ISDIR(inode
->i_mode
))
129 return (mask
& MAY_WRITE
) ? -EPERM
: -ENODATA
;
130 if (S_ISDIR(inode
->i_mode
) && (inode
->i_mode
& S_ISVTX
) &&
131 (mask
& MAY_WRITE
) &&
132 !inode_owner_or_capable(mnt_userns
, inode
))
136 return inode_permission(mnt_userns
, inode
, mask
);
140 * Look for any handler that deals with the specified namespace.
143 xattr_supported_namespace(struct inode
*inode
, const char *prefix
)
145 const struct xattr_handler
**handlers
= inode
->i_sb
->s_xattr
;
146 const struct xattr_handler
*handler
;
149 if (!(inode
->i_opflags
& IOP_XATTR
)) {
150 if (unlikely(is_bad_inode(inode
)))
155 preflen
= strlen(prefix
);
157 for_each_xattr_handler(handlers
, handler
) {
158 if (!strncmp(xattr_prefix(handler
), prefix
, preflen
))
164 EXPORT_SYMBOL(xattr_supported_namespace
);
167 __vfs_setxattr(struct user_namespace
*mnt_userns
, struct dentry
*dentry
,
168 struct inode
*inode
, const char *name
, const void *value
,
169 size_t size
, int flags
)
171 const struct xattr_handler
*handler
;
173 handler
= xattr_resolve_name(inode
, &name
);
175 return PTR_ERR(handler
);
179 value
= ""; /* empty EA, do not remove */
180 return handler
->set(handler
, mnt_userns
, dentry
, inode
, name
, value
,
183 EXPORT_SYMBOL(__vfs_setxattr
);
186 * __vfs_setxattr_noperm - perform setxattr operation without performing
189 * @mnt_userns: user namespace of the mount the inode was found from
190 * @dentry: object to perform setxattr on
191 * @name: xattr name to set
192 * @value: value to set @name to
193 * @size: size of @value
194 * @flags: flags to pass into filesystem operations
196 * returns the result of the internal setxattr or setsecurity operations.
198 * This function requires the caller to lock the inode's i_mutex before it
199 * is executed. It also assumes that the caller will make the appropriate
202 int __vfs_setxattr_noperm(struct user_namespace
*mnt_userns
,
203 struct dentry
*dentry
, const char *name
,
204 const void *value
, size_t size
, int flags
)
206 struct inode
*inode
= dentry
->d_inode
;
208 int issec
= !strncmp(name
, XATTR_SECURITY_PREFIX
,
209 XATTR_SECURITY_PREFIX_LEN
);
212 inode
->i_flags
&= ~S_NOSEC
;
213 if (inode
->i_opflags
& IOP_XATTR
) {
214 error
= __vfs_setxattr(mnt_userns
, dentry
, inode
, name
, value
,
217 fsnotify_xattr(dentry
);
218 security_inode_post_setxattr(dentry
, name
, value
,
222 if (unlikely(is_bad_inode(inode
)))
225 if (error
== -EAGAIN
) {
229 const char *suffix
= name
+ XATTR_SECURITY_PREFIX_LEN
;
231 error
= security_inode_setsecurity(inode
, suffix
, value
,
234 fsnotify_xattr(dentry
);
240 EXPORT_SYMBOL_GPL(__vfs_setxattr_noperm
);
243 * __vfs_setxattr_locked - set an extended attribute while holding the inode
246 * @mnt_userns: user namespace of the mount of the target inode
247 * @dentry: object to perform setxattr on
248 * @name: xattr name to set
249 * @value: value to set @name to
250 * @size: size of @value
251 * @flags: flags to pass into filesystem operations
252 * @delegated_inode: on return, will contain an inode pointer that
253 * a delegation was broken on, NULL if none.
256 __vfs_setxattr_locked(struct user_namespace
*mnt_userns
, struct dentry
*dentry
,
257 const char *name
, const void *value
, size_t size
,
258 int flags
, struct inode
**delegated_inode
)
260 struct inode
*inode
= dentry
->d_inode
;
263 error
= xattr_permission(mnt_userns
, inode
, name
, MAY_WRITE
);
267 error
= security_inode_setxattr(mnt_userns
, dentry
, name
, value
, size
,
272 error
= try_break_deleg(inode
, delegated_inode
);
276 error
= __vfs_setxattr_noperm(mnt_userns
, dentry
, name
, value
,
282 EXPORT_SYMBOL_GPL(__vfs_setxattr_locked
);
285 vfs_setxattr(struct user_namespace
*mnt_userns
, struct dentry
*dentry
,
286 const char *name
, const void *value
, size_t size
, int flags
)
288 struct inode
*inode
= dentry
->d_inode
;
289 struct inode
*delegated_inode
= NULL
;
290 const void *orig_value
= value
;
293 if (size
&& strcmp(name
, XATTR_NAME_CAPS
) == 0) {
294 error
= cap_convert_nscap(mnt_userns
, dentry
, &value
, size
);
302 error
= __vfs_setxattr_locked(mnt_userns
, dentry
, name
, value
, size
,
303 flags
, &delegated_inode
);
306 if (delegated_inode
) {
307 error
= break_deleg_wait(&delegated_inode
);
311 if (value
!= orig_value
)
316 EXPORT_SYMBOL_GPL(vfs_setxattr
);
319 xattr_getsecurity(struct user_namespace
*mnt_userns
, struct inode
*inode
,
320 const char *name
, void *value
, size_t size
)
325 if (!value
|| !size
) {
326 len
= security_inode_getsecurity(mnt_userns
, inode
, name
,
331 len
= security_inode_getsecurity(mnt_userns
, inode
, name
, &buffer
,
339 memcpy(value
, buffer
, len
);
347 * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
349 * Allocate memory, if not already allocated, or re-allocate correct size,
350 * before retrieving the extended attribute.
352 * Returns the result of alloc, if failed, or the getxattr operation.
355 vfs_getxattr_alloc(struct user_namespace
*mnt_userns
, struct dentry
*dentry
,
356 const char *name
, char **xattr_value
, size_t xattr_size
,
359 const struct xattr_handler
*handler
;
360 struct inode
*inode
= dentry
->d_inode
;
361 char *value
= *xattr_value
;
364 error
= xattr_permission(mnt_userns
, inode
, name
, MAY_READ
);
368 handler
= xattr_resolve_name(inode
, &name
);
370 return PTR_ERR(handler
);
373 error
= handler
->get(handler
, dentry
, inode
, name
, NULL
, 0);
377 if (!value
|| (error
> xattr_size
)) {
378 value
= krealloc(*xattr_value
, error
+ 1, flags
);
381 memset(value
, 0, error
+ 1);
384 error
= handler
->get(handler
, dentry
, inode
, name
, value
, error
);
385 *xattr_value
= value
;
388 EXPORT_SYMBOL_GPL(vfs_getxattr_alloc
);
391 __vfs_getxattr(struct dentry
*dentry
, struct inode
*inode
, const char *name
,
392 void *value
, size_t size
)
394 const struct xattr_handler
*handler
;
396 handler
= xattr_resolve_name(inode
, &name
);
398 return PTR_ERR(handler
);
401 return handler
->get(handler
, dentry
, inode
, name
, value
, size
);
403 EXPORT_SYMBOL(__vfs_getxattr
);
406 vfs_getxattr(struct user_namespace
*mnt_userns
, struct dentry
*dentry
,
407 const char *name
, void *value
, size_t size
)
409 struct inode
*inode
= dentry
->d_inode
;
412 error
= xattr_permission(mnt_userns
, inode
, name
, MAY_READ
);
416 error
= security_inode_getxattr(dentry
, name
);
420 if (!strncmp(name
, XATTR_SECURITY_PREFIX
,
421 XATTR_SECURITY_PREFIX_LEN
)) {
422 const char *suffix
= name
+ XATTR_SECURITY_PREFIX_LEN
;
423 int ret
= xattr_getsecurity(mnt_userns
, inode
, suffix
, value
,
426 * Only overwrite the return value if a security module
427 * is actually active.
429 if (ret
== -EOPNOTSUPP
)
434 return __vfs_getxattr(dentry
, inode
, name
, value
, size
);
436 EXPORT_SYMBOL_GPL(vfs_getxattr
);
439 vfs_listxattr(struct dentry
*dentry
, char *list
, size_t size
)
441 struct inode
*inode
= d_inode(dentry
);
444 error
= security_inode_listxattr(dentry
);
447 if (inode
->i_op
->listxattr
&& (inode
->i_opflags
& IOP_XATTR
)) {
448 error
= inode
->i_op
->listxattr(dentry
, list
, size
);
450 error
= security_inode_listsecurity(inode
, list
, size
);
451 if (size
&& error
> size
)
456 EXPORT_SYMBOL_GPL(vfs_listxattr
);
459 __vfs_removexattr(struct user_namespace
*mnt_userns
, struct dentry
*dentry
,
462 struct inode
*inode
= d_inode(dentry
);
463 const struct xattr_handler
*handler
;
465 handler
= xattr_resolve_name(inode
, &name
);
467 return PTR_ERR(handler
);
470 return handler
->set(handler
, mnt_userns
, dentry
, inode
, name
, NULL
, 0,
473 EXPORT_SYMBOL(__vfs_removexattr
);
476 * __vfs_removexattr_noperm - perform removexattr operation without
477 * performing permission checks.
479 * @dentry - object to perform setxattr on
480 * @name - xattr name to set
482 * returns the result of the internal setxattr or setsecurity operations.
484 * This function requires the caller to lock the inode's i_mutex before it
485 * is executed. It also assumes that the caller will make the appropriate
489 __vfs_removexattr_noperm(struct user_namespace
*mnt_userns
,
490 struct dentry
*dentry
, const char *name
)
494 error
=__vfs_removexattr(mnt_userns
, dentry
, name
);
496 fsnotify_xattr(dentry
);
497 evm_inode_post_removexattr(dentry
, name
);
501 EXPORT_SYMBOL_GPL(__vfs_removexattr_noperm
);
504 * __vfs_removexattr_locked - set an extended attribute while holding the inode
507 * @mnt_userns: user namespace of the mount of the target inode
508 * @dentry: object to perform setxattr on
509 * @name: name of xattr to remove
510 * @delegated_inode: on return, will contain an inode pointer that
511 * a delegation was broken on, NULL if none.
514 __vfs_removexattr_locked(struct user_namespace
*mnt_userns
,
515 struct dentry
*dentry
, const char *name
,
516 struct inode
**delegated_inode
)
518 struct inode
*inode
= dentry
->d_inode
;
521 error
= xattr_permission(mnt_userns
, inode
, name
, MAY_WRITE
);
525 error
= security_inode_removexattr(mnt_userns
, dentry
, name
);
529 error
= try_break_deleg(inode
, delegated_inode
);
533 error
= __vfs_removexattr_noperm(mnt_userns
, dentry
, name
);
538 EXPORT_SYMBOL_GPL(__vfs_removexattr_locked
);
541 vfs_removexattr(struct user_namespace
*mnt_userns
, struct dentry
*dentry
,
544 struct inode
*inode
= dentry
->d_inode
;
545 struct inode
*delegated_inode
= NULL
;
550 error
= __vfs_removexattr_locked(mnt_userns
, dentry
,
551 name
, &delegated_inode
);
554 if (delegated_inode
) {
555 error
= break_deleg_wait(&delegated_inode
);
562 EXPORT_SYMBOL_GPL(vfs_removexattr
);
565 * Extended attribute SET operations
568 setxattr(struct user_namespace
*mnt_userns
, struct dentry
*d
,
569 const char __user
*name
, const void __user
*value
, size_t size
,
574 char kname
[XATTR_NAME_MAX
+ 1];
576 if (flags
& ~(XATTR_CREATE
|XATTR_REPLACE
))
579 error
= strncpy_from_user(kname
, name
, sizeof(kname
));
580 if (error
== 0 || error
== sizeof(kname
))
586 if (size
> XATTR_SIZE_MAX
)
588 kvalue
= kvmalloc(size
, GFP_KERNEL
);
591 if (copy_from_user(kvalue
, value
, size
)) {
595 if ((strcmp(kname
, XATTR_NAME_POSIX_ACL_ACCESS
) == 0) ||
596 (strcmp(kname
, XATTR_NAME_POSIX_ACL_DEFAULT
) == 0))
597 posix_acl_fix_xattr_from_user(mnt_userns
, d_inode(d
),
601 error
= vfs_setxattr(mnt_userns
, d
, kname
, kvalue
, size
, flags
);
608 static int path_setxattr(const char __user
*pathname
,
609 const char __user
*name
, const void __user
*value
,
610 size_t size
, int flags
, unsigned int lookup_flags
)
616 error
= user_path_at(AT_FDCWD
, pathname
, lookup_flags
, &path
);
619 error
= mnt_want_write(path
.mnt
);
621 error
= setxattr(mnt_user_ns(path
.mnt
), path
.dentry
, name
,
623 mnt_drop_write(path
.mnt
);
626 if (retry_estale(error
, lookup_flags
)) {
627 lookup_flags
|= LOOKUP_REVAL
;
633 SYSCALL_DEFINE5(setxattr
, const char __user
*, pathname
,
634 const char __user
*, name
, const void __user
*, value
,
635 size_t, size
, int, flags
)
637 return path_setxattr(pathname
, name
, value
, size
, flags
, LOOKUP_FOLLOW
);
640 SYSCALL_DEFINE5(lsetxattr
, const char __user
*, pathname
,
641 const char __user
*, name
, const void __user
*, value
,
642 size_t, size
, int, flags
)
644 return path_setxattr(pathname
, name
, value
, size
, flags
, 0);
647 SYSCALL_DEFINE5(fsetxattr
, int, fd
, const char __user
*, name
,
648 const void __user
*,value
, size_t, size
, int, flags
)
650 struct fd f
= fdget(fd
);
656 error
= mnt_want_write_file(f
.file
);
658 error
= setxattr(file_mnt_user_ns(f
.file
),
659 f
.file
->f_path
.dentry
, name
,
661 mnt_drop_write_file(f
.file
);
668 * Extended attribute GET operations
671 getxattr(struct user_namespace
*mnt_userns
, struct dentry
*d
,
672 const char __user
*name
, void __user
*value
, size_t size
)
676 char kname
[XATTR_NAME_MAX
+ 1];
678 error
= strncpy_from_user(kname
, name
, sizeof(kname
));
679 if (error
== 0 || error
== sizeof(kname
))
685 if (size
> XATTR_SIZE_MAX
)
686 size
= XATTR_SIZE_MAX
;
687 kvalue
= kvzalloc(size
, GFP_KERNEL
);
692 error
= vfs_getxattr(mnt_userns
, d
, kname
, kvalue
, size
);
694 if ((strcmp(kname
, XATTR_NAME_POSIX_ACL_ACCESS
) == 0) ||
695 (strcmp(kname
, XATTR_NAME_POSIX_ACL_DEFAULT
) == 0))
696 posix_acl_fix_xattr_to_user(mnt_userns
, d_inode(d
),
698 if (size
&& copy_to_user(value
, kvalue
, error
))
700 } else if (error
== -ERANGE
&& size
>= XATTR_SIZE_MAX
) {
701 /* The file system tried to returned a value bigger
702 than XATTR_SIZE_MAX bytes. Not possible. */
711 static ssize_t
path_getxattr(const char __user
*pathname
,
712 const char __user
*name
, void __user
*value
,
713 size_t size
, unsigned int lookup_flags
)
718 error
= user_path_at(AT_FDCWD
, pathname
, lookup_flags
, &path
);
721 error
= getxattr(mnt_user_ns(path
.mnt
), path
.dentry
, name
, value
, size
);
723 if (retry_estale(error
, lookup_flags
)) {
724 lookup_flags
|= LOOKUP_REVAL
;
730 SYSCALL_DEFINE4(getxattr
, const char __user
*, pathname
,
731 const char __user
*, name
, void __user
*, value
, size_t, size
)
733 return path_getxattr(pathname
, name
, value
, size
, LOOKUP_FOLLOW
);
736 SYSCALL_DEFINE4(lgetxattr
, const char __user
*, pathname
,
737 const char __user
*, name
, void __user
*, value
, size_t, size
)
739 return path_getxattr(pathname
, name
, value
, size
, 0);
742 SYSCALL_DEFINE4(fgetxattr
, int, fd
, const char __user
*, name
,
743 void __user
*, value
, size_t, size
)
745 struct fd f
= fdget(fd
);
746 ssize_t error
= -EBADF
;
751 error
= getxattr(file_mnt_user_ns(f
.file
), f
.file
->f_path
.dentry
,
758 * Extended attribute LIST operations
761 listxattr(struct dentry
*d
, char __user
*list
, size_t size
)
767 if (size
> XATTR_LIST_MAX
)
768 size
= XATTR_LIST_MAX
;
769 klist
= kvmalloc(size
, GFP_KERNEL
);
774 error
= vfs_listxattr(d
, klist
, size
);
776 if (size
&& copy_to_user(list
, klist
, error
))
778 } else if (error
== -ERANGE
&& size
>= XATTR_LIST_MAX
) {
779 /* The file system tried to returned a list bigger
780 than XATTR_LIST_MAX bytes. Not possible. */
789 static ssize_t
path_listxattr(const char __user
*pathname
, char __user
*list
,
790 size_t size
, unsigned int lookup_flags
)
795 error
= user_path_at(AT_FDCWD
, pathname
, lookup_flags
, &path
);
798 error
= listxattr(path
.dentry
, list
, size
);
800 if (retry_estale(error
, lookup_flags
)) {
801 lookup_flags
|= LOOKUP_REVAL
;
807 SYSCALL_DEFINE3(listxattr
, const char __user
*, pathname
, char __user
*, list
,
810 return path_listxattr(pathname
, list
, size
, LOOKUP_FOLLOW
);
813 SYSCALL_DEFINE3(llistxattr
, const char __user
*, pathname
, char __user
*, list
,
816 return path_listxattr(pathname
, list
, size
, 0);
819 SYSCALL_DEFINE3(flistxattr
, int, fd
, char __user
*, list
, size_t, size
)
821 struct fd f
= fdget(fd
);
822 ssize_t error
= -EBADF
;
827 error
= listxattr(f
.file
->f_path
.dentry
, list
, size
);
833 * Extended attribute REMOVE operations
836 removexattr(struct user_namespace
*mnt_userns
, struct dentry
*d
,
837 const char __user
*name
)
840 char kname
[XATTR_NAME_MAX
+ 1];
842 error
= strncpy_from_user(kname
, name
, sizeof(kname
));
843 if (error
== 0 || error
== sizeof(kname
))
848 return vfs_removexattr(mnt_userns
, d
, kname
);
851 static int path_removexattr(const char __user
*pathname
,
852 const char __user
*name
, unsigned int lookup_flags
)
857 error
= user_path_at(AT_FDCWD
, pathname
, lookup_flags
, &path
);
860 error
= mnt_want_write(path
.mnt
);
862 error
= removexattr(mnt_user_ns(path
.mnt
), path
.dentry
, name
);
863 mnt_drop_write(path
.mnt
);
866 if (retry_estale(error
, lookup_flags
)) {
867 lookup_flags
|= LOOKUP_REVAL
;
873 SYSCALL_DEFINE2(removexattr
, const char __user
*, pathname
,
874 const char __user
*, name
)
876 return path_removexattr(pathname
, name
, LOOKUP_FOLLOW
);
879 SYSCALL_DEFINE2(lremovexattr
, const char __user
*, pathname
,
880 const char __user
*, name
)
882 return path_removexattr(pathname
, name
, 0);
885 SYSCALL_DEFINE2(fremovexattr
, int, fd
, const char __user
*, name
)
887 struct fd f
= fdget(fd
);
893 error
= mnt_want_write_file(f
.file
);
895 error
= removexattr(file_mnt_user_ns(f
.file
),
896 f
.file
->f_path
.dentry
, name
);
897 mnt_drop_write_file(f
.file
);
904 * Combine the results of the list() operation from every xattr_handler in the
908 generic_listxattr(struct dentry
*dentry
, char *buffer
, size_t buffer_size
)
910 const struct xattr_handler
*handler
, **handlers
= dentry
->d_sb
->s_xattr
;
911 unsigned int size
= 0;
914 for_each_xattr_handler(handlers
, handler
) {
915 if (!handler
->name
||
916 (handler
->list
&& !handler
->list(dentry
)))
918 size
+= strlen(handler
->name
) + 1;
924 for_each_xattr_handler(handlers
, handler
) {
925 if (!handler
->name
||
926 (handler
->list
&& !handler
->list(dentry
)))
928 len
= strlen(handler
->name
);
929 if (len
+ 1 > buffer_size
)
931 memcpy(buf
, handler
->name
, len
+ 1);
933 buffer_size
-= len
+ 1;
939 EXPORT_SYMBOL(generic_listxattr
);
942 * xattr_full_name - Compute full attribute name from suffix
944 * @handler: handler of the xattr_handler operation
945 * @name: name passed to the xattr_handler operation
947 * The get and set xattr handler operations are called with the remainder of
948 * the attribute name after skipping the handler's prefix: for example, "foo"
949 * is passed to the get operation of a handler with prefix "user." to get
950 * attribute "user.foo". The full name is still "there" in the name though.
952 * Note: the list xattr handler operation when called from the vfs is passed a
953 * NULL name; some file systems use this operation internally, with varying
956 const char *xattr_full_name(const struct xattr_handler
*handler
,
959 size_t prefix_len
= strlen(xattr_prefix(handler
));
961 return name
- prefix_len
;
963 EXPORT_SYMBOL(xattr_full_name
);
966 * Allocate new xattr and copy in the value; but leave the name to callers.
968 struct simple_xattr
*simple_xattr_alloc(const void *value
, size_t size
)
970 struct simple_xattr
*new_xattr
;
974 len
= sizeof(*new_xattr
) + size
;
975 if (len
< sizeof(*new_xattr
))
978 new_xattr
= kvmalloc(len
, GFP_KERNEL
);
982 new_xattr
->size
= size
;
983 memcpy(new_xattr
->value
, value
, size
);
988 * xattr GET operation for in-memory/pseudo filesystems
990 int simple_xattr_get(struct simple_xattrs
*xattrs
, const char *name
,
991 void *buffer
, size_t size
)
993 struct simple_xattr
*xattr
;
996 spin_lock(&xattrs
->lock
);
997 list_for_each_entry(xattr
, &xattrs
->head
, list
) {
998 if (strcmp(name
, xattr
->name
))
1003 if (size
< xattr
->size
)
1006 memcpy(buffer
, xattr
->value
, xattr
->size
);
1010 spin_unlock(&xattrs
->lock
);
1015 * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
1016 * @xattrs: target simple_xattr list
1017 * @name: name of the extended attribute
1018 * @value: value of the xattr. If %NULL, will remove the attribute.
1019 * @size: size of the new xattr
1020 * @flags: %XATTR_{CREATE|REPLACE}
1021 * @removed_size: returns size of the removed xattr, -1 if none removed
1023 * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
1024 * with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist;
1025 * otherwise, fails with -ENODATA.
1027 * Returns 0 on success, -errno on failure.
1029 int simple_xattr_set(struct simple_xattrs
*xattrs
, const char *name
,
1030 const void *value
, size_t size
, int flags
,
1031 ssize_t
*removed_size
)
1033 struct simple_xattr
*xattr
;
1034 struct simple_xattr
*new_xattr
= NULL
;
1040 /* value == NULL means remove */
1042 new_xattr
= simple_xattr_alloc(value
, size
);
1046 new_xattr
->name
= kstrdup(name
, GFP_KERNEL
);
1047 if (!new_xattr
->name
) {
1053 spin_lock(&xattrs
->lock
);
1054 list_for_each_entry(xattr
, &xattrs
->head
, list
) {
1055 if (!strcmp(name
, xattr
->name
)) {
1056 if (flags
& XATTR_CREATE
) {
1059 } else if (new_xattr
) {
1060 list_replace(&xattr
->list
, &new_xattr
->list
);
1062 *removed_size
= xattr
->size
;
1064 list_del(&xattr
->list
);
1066 *removed_size
= xattr
->size
;
1071 if (flags
& XATTR_REPLACE
) {
1075 list_add(&new_xattr
->list
, &xattrs
->head
);
1079 spin_unlock(&xattrs
->lock
);
1088 static bool xattr_is_trusted(const char *name
)
1090 return !strncmp(name
, XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
);
1093 static int xattr_list_one(char **buffer
, ssize_t
*remaining_size
,
1096 size_t len
= strlen(name
) + 1;
1098 if (*remaining_size
< len
)
1100 memcpy(*buffer
, name
, len
);
1103 *remaining_size
-= len
;
1108 * xattr LIST operation for in-memory/pseudo filesystems
1110 ssize_t
simple_xattr_list(struct inode
*inode
, struct simple_xattrs
*xattrs
,
1111 char *buffer
, size_t size
)
1113 bool trusted
= capable(CAP_SYS_ADMIN
);
1114 struct simple_xattr
*xattr
;
1115 ssize_t remaining_size
= size
;
1118 #ifdef CONFIG_FS_POSIX_ACL
1119 if (IS_POSIXACL(inode
)) {
1121 err
= xattr_list_one(&buffer
, &remaining_size
,
1122 XATTR_NAME_POSIX_ACL_ACCESS
);
1126 if (inode
->i_default_acl
) {
1127 err
= xattr_list_one(&buffer
, &remaining_size
,
1128 XATTR_NAME_POSIX_ACL_DEFAULT
);
1135 spin_lock(&xattrs
->lock
);
1136 list_for_each_entry(xattr
, &xattrs
->head
, list
) {
1137 /* skip "trusted." attributes for unprivileged callers */
1138 if (!trusted
&& xattr_is_trusted(xattr
->name
))
1141 err
= xattr_list_one(&buffer
, &remaining_size
, xattr
->name
);
1145 spin_unlock(&xattrs
->lock
);
1147 return err
? err
: size
- remaining_size
;
1151 * Adds an extended attribute to the list
1153 void simple_xattr_list_add(struct simple_xattrs
*xattrs
,
1154 struct simple_xattr
*new_xattr
)
1156 spin_lock(&xattrs
->lock
);
1157 list_add(&new_xattr
->list
, &xattrs
->head
);
1158 spin_unlock(&xattrs
->lock
);