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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 File: fs/xattr.c
4
5 Extended attribute handling.
6
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>
10 */
11#include <linux/fs.h>
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>
25
26#include <linux/uaccess.h>
27
28static const char *
29strcmp_prefix(const char *a, const char *a_prefix)
30{
31 while (*a_prefix && *a == *a_prefix) {
32 a++;
33 a_prefix++;
34 }
35 return *a_prefix ? NULL : a;
36}
37
38/*
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.
43 */
44#define for_each_xattr_handler(handlers, handler) \
45 if (handlers) \
46 for ((handler) = *(handlers)++; \
47 (handler) != NULL; \
48 (handler) = *(handlers)++)
49
50/*
51 * Find the xattr_handler with the matching prefix.
52 */
53static const struct xattr_handler *
54xattr_resolve_name(struct inode *inode, const char **name)
55{
56 const struct xattr_handler **handlers = inode->i_sb->s_xattr;
57 const struct xattr_handler *handler;
58
59 if (!(inode->i_opflags & IOP_XATTR)) {
60 if (unlikely(is_bad_inode(inode)))
61 return ERR_PTR(-EIO);
62 return ERR_PTR(-EOPNOTSUPP);
63 }
64 for_each_xattr_handler(handlers, handler) {
65 const char *n;
66
67 n = strcmp_prefix(*name, xattr_prefix(handler));
68 if (n) {
69 if (!handler->prefix ^ !*n) {
70 if (*n)
71 continue;
72 return ERR_PTR(-EINVAL);
73 }
74 *name = n;
75 return handler;
76 }
77 }
78 return ERR_PTR(-EOPNOTSUPP);
79}
80
81/*
82 * Check permissions for extended attribute access. This is a bit complicated
83 * because different namespaces have very different rules.
84 */
85static int
86xattr_permission(struct inode *inode, const char *name, int mask)
87{
88 /*
89 * We can never set or remove an extended attribute on a read-only
90 * filesystem or on an immutable / append-only inode.
91 */
92 if (mask & MAY_WRITE) {
93 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
94 return -EPERM;
95 /*
96 * Updating an xattr will likely cause i_uid and i_gid
97 * to be writen back improperly if their true value is
98 * unknown to the vfs.
99 */
100 if (HAS_UNMAPPED_ID(inode))
101 return -EPERM;
102 }
103
104 /*
105 * No restriction for security.* and system.* from the VFS. Decision
106 * on these is left to the underlying filesystem / security module.
107 */
108 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
109 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
110 return 0;
111
112 /*
113 * The trusted.* namespace can only be accessed by privileged users.
114 */
115 if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
116 if (!capable(CAP_SYS_ADMIN))
117 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
118 return 0;
119 }
120
121 /*
122 * In the user.* namespace, only regular files and directories can have
123 * extended attributes. For sticky directories, only the owner and
124 * privileged users can write attributes.
125 */
126 if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
127 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
128 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
129 if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
130 (mask & MAY_WRITE) && !inode_owner_or_capable(inode))
131 return -EPERM;
132 }
133
134 return inode_permission(inode, mask);
135}
136
137int
138__vfs_setxattr(struct dentry *dentry, struct inode *inode, const char *name,
139 const void *value, size_t size, int flags)
140{
141 const struct xattr_handler *handler;
142
143 handler = xattr_resolve_name(inode, &name);
144 if (IS_ERR(handler))
145 return PTR_ERR(handler);
146 if (!handler->set)
147 return -EOPNOTSUPP;
148 if (size == 0)
149 value = ""; /* empty EA, do not remove */
150 return handler->set(handler, dentry, inode, name, value, size, flags);
151}
152EXPORT_SYMBOL(__vfs_setxattr);
153
154/**
155 * __vfs_setxattr_noperm - perform setxattr operation without performing
156 * permission checks.
157 *
158 * @dentry - object to perform setxattr on
159 * @name - xattr name to set
160 * @value - value to set @name to
161 * @size - size of @value
162 * @flags - flags to pass into filesystem operations
163 *
164 * returns the result of the internal setxattr or setsecurity operations.
165 *
166 * This function requires the caller to lock the inode's i_mutex before it
167 * is executed. It also assumes that the caller will make the appropriate
168 * permission checks.
169 */
170int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
171 const void *value, size_t size, int flags)
172{
173 struct inode *inode = dentry->d_inode;
174 int error = -EAGAIN;
175 int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
176 XATTR_SECURITY_PREFIX_LEN);
177
178 if (issec)
179 inode->i_flags &= ~S_NOSEC;
180 if (inode->i_opflags & IOP_XATTR) {
181 error = __vfs_setxattr(dentry, inode, name, value, size, flags);
182 if (!error) {
183 fsnotify_xattr(dentry);
184 security_inode_post_setxattr(dentry, name, value,
185 size, flags);
186 }
187 } else {
188 if (unlikely(is_bad_inode(inode)))
189 return -EIO;
190 }
191 if (error == -EAGAIN) {
192 error = -EOPNOTSUPP;
193
194 if (issec) {
195 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
196
197 error = security_inode_setsecurity(inode, suffix, value,
198 size, flags);
199 if (!error)
200 fsnotify_xattr(dentry);
201 }
202 }
203
204 return error;
205}
206
207
208int
209vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
210 size_t size, int flags)
211{
212 struct inode *inode = dentry->d_inode;
213 int error;
214
215 error = xattr_permission(inode, name, MAY_WRITE);
216 if (error)
217 return error;
218
219 inode_lock(inode);
220 error = security_inode_setxattr(dentry, name, value, size, flags);
221 if (error)
222 goto out;
223
224 error = __vfs_setxattr_noperm(dentry, name, value, size, flags);
225
226out:
227 inode_unlock(inode);
228 return error;
229}
230EXPORT_SYMBOL_GPL(vfs_setxattr);
231
232static ssize_t
233xattr_getsecurity(struct inode *inode, const char *name, void *value,
234 size_t size)
235{
236 void *buffer = NULL;
237 ssize_t len;
238
239 if (!value || !size) {
240 len = security_inode_getsecurity(inode, name, &buffer, false);
241 goto out_noalloc;
242 }
243
244 len = security_inode_getsecurity(inode, name, &buffer, true);
245 if (len < 0)
246 return len;
247 if (size < len) {
248 len = -ERANGE;
249 goto out;
250 }
251 memcpy(value, buffer, len);
252out:
253 kfree(buffer);
254out_noalloc:
255 return len;
256}
257
258/*
259 * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
260 *
261 * Allocate memory, if not already allocated, or re-allocate correct size,
262 * before retrieving the extended attribute.
263 *
264 * Returns the result of alloc, if failed, or the getxattr operation.
265 */
266ssize_t
267vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value,
268 size_t xattr_size, gfp_t flags)
269{
270 const struct xattr_handler *handler;
271 struct inode *inode = dentry->d_inode;
272 char *value = *xattr_value;
273 int error;
274
275 error = xattr_permission(inode, name, MAY_READ);
276 if (error)
277 return error;
278
279 handler = xattr_resolve_name(inode, &name);
280 if (IS_ERR(handler))
281 return PTR_ERR(handler);
282 if (!handler->get)
283 return -EOPNOTSUPP;
284 error = handler->get(handler, dentry, inode, name, NULL, 0);
285 if (error < 0)
286 return error;
287
288 if (!value || (error > xattr_size)) {
289 value = krealloc(*xattr_value, error + 1, flags);
290 if (!value)
291 return -ENOMEM;
292 memset(value, 0, error + 1);
293 }
294
295 error = handler->get(handler, dentry, inode, name, value, error);
296 *xattr_value = value;
297 return error;
298}
299
300ssize_t
301__vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
302 void *value, size_t size)
303{
304 const struct xattr_handler *handler;
305
306 handler = xattr_resolve_name(inode, &name);
307 if (IS_ERR(handler))
308 return PTR_ERR(handler);
309 if (!handler->get)
310 return -EOPNOTSUPP;
311 return handler->get(handler, dentry, inode, name, value, size);
312}
313EXPORT_SYMBOL(__vfs_getxattr);
314
315ssize_t
316vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
317{
318 struct inode *inode = dentry->d_inode;
319 int error;
320
321 error = xattr_permission(inode, name, MAY_READ);
322 if (error)
323 return error;
324
325 error = security_inode_getxattr(dentry, name);
326 if (error)
327 return error;
328
329 if (!strncmp(name, XATTR_SECURITY_PREFIX,
330 XATTR_SECURITY_PREFIX_LEN)) {
331 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
332 int ret = xattr_getsecurity(inode, suffix, value, size);
333 /*
334 * Only overwrite the return value if a security module
335 * is actually active.
336 */
337 if (ret == -EOPNOTSUPP)
338 goto nolsm;
339 return ret;
340 }
341nolsm:
342 return __vfs_getxattr(dentry, inode, name, value, size);
343}
344EXPORT_SYMBOL_GPL(vfs_getxattr);
345
346ssize_t
347vfs_listxattr(struct dentry *dentry, char *list, size_t size)
348{
349 struct inode *inode = d_inode(dentry);
350 ssize_t error;
351
352 error = security_inode_listxattr(dentry);
353 if (error)
354 return error;
355 if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) {
356 error = inode->i_op->listxattr(dentry, list, size);
357 } else {
358 error = security_inode_listsecurity(inode, list, size);
359 if (size && error > size)
360 error = -ERANGE;
361 }
362 return error;
363}
364EXPORT_SYMBOL_GPL(vfs_listxattr);
365
366int
367__vfs_removexattr(struct dentry *dentry, const char *name)
368{
369 struct inode *inode = d_inode(dentry);
370 const struct xattr_handler *handler;
371
372 handler = xattr_resolve_name(inode, &name);
373 if (IS_ERR(handler))
374 return PTR_ERR(handler);
375 if (!handler->set)
376 return -EOPNOTSUPP;
377 return handler->set(handler, dentry, inode, name, NULL, 0, XATTR_REPLACE);
378}
379EXPORT_SYMBOL(__vfs_removexattr);
380
381int
382vfs_removexattr(struct dentry *dentry, const char *name)
383{
384 struct inode *inode = dentry->d_inode;
385 int error;
386
387 error = xattr_permission(inode, name, MAY_WRITE);
388 if (error)
389 return error;
390
391 inode_lock(inode);
392 error = security_inode_removexattr(dentry, name);
393 if (error)
394 goto out;
395
396 error = __vfs_removexattr(dentry, name);
397
398 if (!error) {
399 fsnotify_xattr(dentry);
400 evm_inode_post_removexattr(dentry, name);
401 }
402
403out:
404 inode_unlock(inode);
405 return error;
406}
407EXPORT_SYMBOL_GPL(vfs_removexattr);
408
409
410/*
411 * Extended attribute SET operations
412 */
413static long
414setxattr(struct dentry *d, const char __user *name, const void __user *value,
415 size_t size, int flags)
416{
417 int error;
418 void *kvalue = NULL;
419 char kname[XATTR_NAME_MAX + 1];
420
421 if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
422 return -EINVAL;
423
424 error = strncpy_from_user(kname, name, sizeof(kname));
425 if (error == 0 || error == sizeof(kname))
426 error = -ERANGE;
427 if (error < 0)
428 return error;
429
430 if (size) {
431 if (size > XATTR_SIZE_MAX)
432 return -E2BIG;
433 kvalue = kvmalloc(size, GFP_KERNEL);
434 if (!kvalue)
435 return -ENOMEM;
436 if (copy_from_user(kvalue, value, size)) {
437 error = -EFAULT;
438 goto out;
439 }
440 if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
441 (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
442 posix_acl_fix_xattr_from_user(kvalue, size);
443 else if (strcmp(kname, XATTR_NAME_CAPS) == 0) {
444 error = cap_convert_nscap(d, &kvalue, size);
445 if (error < 0)
446 goto out;
447 size = error;
448 }
449 }
450
451 error = vfs_setxattr(d, kname, kvalue, size, flags);
452out:
453 kvfree(kvalue);
454
455 return error;
456}
457
458static int path_setxattr(const char __user *pathname,
459 const char __user *name, const void __user *value,
460 size_t size, int flags, unsigned int lookup_flags)
461{
462 struct path path;
463 int error;
464retry:
465 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
466 if (error)
467 return error;
468 error = mnt_want_write(path.mnt);
469 if (!error) {
470 error = setxattr(path.dentry, name, value, size, flags);
471 mnt_drop_write(path.mnt);
472 }
473 path_put(&path);
474 if (retry_estale(error, lookup_flags)) {
475 lookup_flags |= LOOKUP_REVAL;
476 goto retry;
477 }
478 return error;
479}
480
481SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
482 const char __user *, name, const void __user *, value,
483 size_t, size, int, flags)
484{
485 return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW);
486}
487
488SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
489 const char __user *, name, const void __user *, value,
490 size_t, size, int, flags)
491{
492 return path_setxattr(pathname, name, value, size, flags, 0);
493}
494
495SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
496 const void __user *,value, size_t, size, int, flags)
497{
498 struct fd f = fdget(fd);
499 int error = -EBADF;
500
501 if (!f.file)
502 return error;
503 audit_file(f.file);
504 error = mnt_want_write_file(f.file);
505 if (!error) {
506 error = setxattr(f.file->f_path.dentry, name, value, size, flags);
507 mnt_drop_write_file(f.file);
508 }
509 fdput(f);
510 return error;
511}
512
513/*
514 * Extended attribute GET operations
515 */
516static ssize_t
517getxattr(struct dentry *d, const char __user *name, void __user *value,
518 size_t size)
519{
520 ssize_t error;
521 void *kvalue = NULL;
522 char kname[XATTR_NAME_MAX + 1];
523
524 error = strncpy_from_user(kname, name, sizeof(kname));
525 if (error == 0 || error == sizeof(kname))
526 error = -ERANGE;
527 if (error < 0)
528 return error;
529
530 if (size) {
531 if (size > XATTR_SIZE_MAX)
532 size = XATTR_SIZE_MAX;
533 kvalue = kvzalloc(size, GFP_KERNEL);
534 if (!kvalue)
535 return -ENOMEM;
536 }
537
538 error = vfs_getxattr(d, kname, kvalue, size);
539 if (error > 0) {
540 if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
541 (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
542 posix_acl_fix_xattr_to_user(kvalue, error);
543 if (size && copy_to_user(value, kvalue, error))
544 error = -EFAULT;
545 } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
546 /* The file system tried to returned a value bigger
547 than XATTR_SIZE_MAX bytes. Not possible. */
548 error = -E2BIG;
549 }
550
551 kvfree(kvalue);
552
553 return error;
554}
555
556static ssize_t path_getxattr(const char __user *pathname,
557 const char __user *name, void __user *value,
558 size_t size, unsigned int lookup_flags)
559{
560 struct path path;
561 ssize_t error;
562retry:
563 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
564 if (error)
565 return error;
566 error = getxattr(path.dentry, name, value, size);
567 path_put(&path);
568 if (retry_estale(error, lookup_flags)) {
569 lookup_flags |= LOOKUP_REVAL;
570 goto retry;
571 }
572 return error;
573}
574
575SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
576 const char __user *, name, void __user *, value, size_t, size)
577{
578 return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW);
579}
580
581SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
582 const char __user *, name, void __user *, value, size_t, size)
583{
584 return path_getxattr(pathname, name, value, size, 0);
585}
586
587SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
588 void __user *, value, size_t, size)
589{
590 struct fd f = fdget(fd);
591 ssize_t error = -EBADF;
592
593 if (!f.file)
594 return error;
595 audit_file(f.file);
596 error = getxattr(f.file->f_path.dentry, name, value, size);
597 fdput(f);
598 return error;
599}
600
601/*
602 * Extended attribute LIST operations
603 */
604static ssize_t
605listxattr(struct dentry *d, char __user *list, size_t size)
606{
607 ssize_t error;
608 char *klist = NULL;
609
610 if (size) {
611 if (size > XATTR_LIST_MAX)
612 size = XATTR_LIST_MAX;
613 klist = kvmalloc(size, GFP_KERNEL);
614 if (!klist)
615 return -ENOMEM;
616 }
617
618 error = vfs_listxattr(d, klist, size);
619 if (error > 0) {
620 if (size && copy_to_user(list, klist, error))
621 error = -EFAULT;
622 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
623 /* The file system tried to returned a list bigger
624 than XATTR_LIST_MAX bytes. Not possible. */
625 error = -E2BIG;
626 }
627
628 kvfree(klist);
629
630 return error;
631}
632
633static ssize_t path_listxattr(const char __user *pathname, char __user *list,
634 size_t size, unsigned int lookup_flags)
635{
636 struct path path;
637 ssize_t error;
638retry:
639 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
640 if (error)
641 return error;
642 error = listxattr(path.dentry, list, size);
643 path_put(&path);
644 if (retry_estale(error, lookup_flags)) {
645 lookup_flags |= LOOKUP_REVAL;
646 goto retry;
647 }
648 return error;
649}
650
651SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
652 size_t, size)
653{
654 return path_listxattr(pathname, list, size, LOOKUP_FOLLOW);
655}
656
657SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
658 size_t, size)
659{
660 return path_listxattr(pathname, list, size, 0);
661}
662
663SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
664{
665 struct fd f = fdget(fd);
666 ssize_t error = -EBADF;
667
668 if (!f.file)
669 return error;
670 audit_file(f.file);
671 error = listxattr(f.file->f_path.dentry, list, size);
672 fdput(f);
673 return error;
674}
675
676/*
677 * Extended attribute REMOVE operations
678 */
679static long
680removexattr(struct dentry *d, const char __user *name)
681{
682 int error;
683 char kname[XATTR_NAME_MAX + 1];
684
685 error = strncpy_from_user(kname, name, sizeof(kname));
686 if (error == 0 || error == sizeof(kname))
687 error = -ERANGE;
688 if (error < 0)
689 return error;
690
691 return vfs_removexattr(d, kname);
692}
693
694static int path_removexattr(const char __user *pathname,
695 const char __user *name, unsigned int lookup_flags)
696{
697 struct path path;
698 int error;
699retry:
700 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
701 if (error)
702 return error;
703 error = mnt_want_write(path.mnt);
704 if (!error) {
705 error = removexattr(path.dentry, name);
706 mnt_drop_write(path.mnt);
707 }
708 path_put(&path);
709 if (retry_estale(error, lookup_flags)) {
710 lookup_flags |= LOOKUP_REVAL;
711 goto retry;
712 }
713 return error;
714}
715
716SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
717 const char __user *, name)
718{
719 return path_removexattr(pathname, name, LOOKUP_FOLLOW);
720}
721
722SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
723 const char __user *, name)
724{
725 return path_removexattr(pathname, name, 0);
726}
727
728SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
729{
730 struct fd f = fdget(fd);
731 int error = -EBADF;
732
733 if (!f.file)
734 return error;
735 audit_file(f.file);
736 error = mnt_want_write_file(f.file);
737 if (!error) {
738 error = removexattr(f.file->f_path.dentry, name);
739 mnt_drop_write_file(f.file);
740 }
741 fdput(f);
742 return error;
743}
744
745/*
746 * Combine the results of the list() operation from every xattr_handler in the
747 * list.
748 */
749ssize_t
750generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
751{
752 const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
753 unsigned int size = 0;
754
755 if (!buffer) {
756 for_each_xattr_handler(handlers, handler) {
757 if (!handler->name ||
758 (handler->list && !handler->list(dentry)))
759 continue;
760 size += strlen(handler->name) + 1;
761 }
762 } else {
763 char *buf = buffer;
764 size_t len;
765
766 for_each_xattr_handler(handlers, handler) {
767 if (!handler->name ||
768 (handler->list && !handler->list(dentry)))
769 continue;
770 len = strlen(handler->name);
771 if (len + 1 > buffer_size)
772 return -ERANGE;
773 memcpy(buf, handler->name, len + 1);
774 buf += len + 1;
775 buffer_size -= len + 1;
776 }
777 size = buf - buffer;
778 }
779 return size;
780}
781EXPORT_SYMBOL(generic_listxattr);
782
783/**
784 * xattr_full_name - Compute full attribute name from suffix
785 *
786 * @handler: handler of the xattr_handler operation
787 * @name: name passed to the xattr_handler operation
788 *
789 * The get and set xattr handler operations are called with the remainder of
790 * the attribute name after skipping the handler's prefix: for example, "foo"
791 * is passed to the get operation of a handler with prefix "user." to get
792 * attribute "user.foo". The full name is still "there" in the name though.
793 *
794 * Note: the list xattr handler operation when called from the vfs is passed a
795 * NULL name; some file systems use this operation internally, with varying
796 * semantics.
797 */
798const char *xattr_full_name(const struct xattr_handler *handler,
799 const char *name)
800{
801 size_t prefix_len = strlen(xattr_prefix(handler));
802
803 return name - prefix_len;
804}
805EXPORT_SYMBOL(xattr_full_name);
806
807/*
808 * Allocate new xattr and copy in the value; but leave the name to callers.
809 */
810struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
811{
812 struct simple_xattr *new_xattr;
813 size_t len;
814
815 /* wrap around? */
816 len = sizeof(*new_xattr) + size;
817 if (len < sizeof(*new_xattr))
818 return NULL;
819
820 new_xattr = kmalloc(len, GFP_KERNEL);
821 if (!new_xattr)
822 return NULL;
823
824 new_xattr->size = size;
825 memcpy(new_xattr->value, value, size);
826 return new_xattr;
827}
828
829/*
830 * xattr GET operation for in-memory/pseudo filesystems
831 */
832int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
833 void *buffer, size_t size)
834{
835 struct simple_xattr *xattr;
836 int ret = -ENODATA;
837
838 spin_lock(&xattrs->lock);
839 list_for_each_entry(xattr, &xattrs->head, list) {
840 if (strcmp(name, xattr->name))
841 continue;
842
843 ret = xattr->size;
844 if (buffer) {
845 if (size < xattr->size)
846 ret = -ERANGE;
847 else
848 memcpy(buffer, xattr->value, xattr->size);
849 }
850 break;
851 }
852 spin_unlock(&xattrs->lock);
853 return ret;
854}
855
856/**
857 * simple_xattr_set - xattr SET operation for in-memory/pseudo filesystems
858 * @xattrs: target simple_xattr list
859 * @name: name of the extended attribute
860 * @value: value of the xattr. If %NULL, will remove the attribute.
861 * @size: size of the new xattr
862 * @flags: %XATTR_{CREATE|REPLACE}
863 *
864 * %XATTR_CREATE is set, the xattr shouldn't exist already; otherwise fails
865 * with -EEXIST. If %XATTR_REPLACE is set, the xattr should exist;
866 * otherwise, fails with -ENODATA.
867 *
868 * Returns 0 on success, -errno on failure.
869 */
870int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
871 const void *value, size_t size, int flags)
872{
873 struct simple_xattr *xattr;
874 struct simple_xattr *new_xattr = NULL;
875 int err = 0;
876
877 /* value == NULL means remove */
878 if (value) {
879 new_xattr = simple_xattr_alloc(value, size);
880 if (!new_xattr)
881 return -ENOMEM;
882
883 new_xattr->name = kstrdup(name, GFP_KERNEL);
884 if (!new_xattr->name) {
885 kfree(new_xattr);
886 return -ENOMEM;
887 }
888 }
889
890 spin_lock(&xattrs->lock);
891 list_for_each_entry(xattr, &xattrs->head, list) {
892 if (!strcmp(name, xattr->name)) {
893 if (flags & XATTR_CREATE) {
894 xattr = new_xattr;
895 err = -EEXIST;
896 } else if (new_xattr) {
897 list_replace(&xattr->list, &new_xattr->list);
898 } else {
899 list_del(&xattr->list);
900 }
901 goto out;
902 }
903 }
904 if (flags & XATTR_REPLACE) {
905 xattr = new_xattr;
906 err = -ENODATA;
907 } else {
908 list_add(&new_xattr->list, &xattrs->head);
909 xattr = NULL;
910 }
911out:
912 spin_unlock(&xattrs->lock);
913 if (xattr) {
914 kfree(xattr->name);
915 kfree(xattr);
916 }
917 return err;
918
919}
920
921static bool xattr_is_trusted(const char *name)
922{
923 return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
924}
925
926static int xattr_list_one(char **buffer, ssize_t *remaining_size,
927 const char *name)
928{
929 size_t len = strlen(name) + 1;
930 if (*buffer) {
931 if (*remaining_size < len)
932 return -ERANGE;
933 memcpy(*buffer, name, len);
934 *buffer += len;
935 }
936 *remaining_size -= len;
937 return 0;
938}
939
940/*
941 * xattr LIST operation for in-memory/pseudo filesystems
942 */
943ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
944 char *buffer, size_t size)
945{
946 bool trusted = capable(CAP_SYS_ADMIN);
947 struct simple_xattr *xattr;
948 ssize_t remaining_size = size;
949 int err = 0;
950
951#ifdef CONFIG_FS_POSIX_ACL
952 if (IS_POSIXACL(inode)) {
953 if (inode->i_acl) {
954 err = xattr_list_one(&buffer, &remaining_size,
955 XATTR_NAME_POSIX_ACL_ACCESS);
956 if (err)
957 return err;
958 }
959 if (inode->i_default_acl) {
960 err = xattr_list_one(&buffer, &remaining_size,
961 XATTR_NAME_POSIX_ACL_DEFAULT);
962 if (err)
963 return err;
964 }
965 }
966#endif
967
968 spin_lock(&xattrs->lock);
969 list_for_each_entry(xattr, &xattrs->head, list) {
970 /* skip "trusted." attributes for unprivileged callers */
971 if (!trusted && xattr_is_trusted(xattr->name))
972 continue;
973
974 err = xattr_list_one(&buffer, &remaining_size, xattr->name);
975 if (err)
976 break;
977 }
978 spin_unlock(&xattrs->lock);
979
980 return err ? err : size - remaining_size;
981}
982
983/*
984 * Adds an extended attribute to the list
985 */
986void simple_xattr_list_add(struct simple_xattrs *xattrs,
987 struct simple_xattr *new_xattr)
988{
989 spin_lock(&xattrs->lock);
990 list_add(&new_xattr->list, &xattrs->head);
991 spin_unlock(&xattrs->lock);
992}
1/*
2 File: fs/xattr.c
3
4 Extended attribute handling.
5
6 Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
7 Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
8 Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
9 */
10#include <linux/fs.h>
11#include <linux/slab.h>
12#include <linux/file.h>
13#include <linux/xattr.h>
14#include <linux/mount.h>
15#include <linux/namei.h>
16#include <linux/security.h>
17#include <linux/syscalls.h>
18#include <linux/module.h>
19#include <linux/fsnotify.h>
20#include <linux/audit.h>
21#include <asm/uaccess.h>
22
23
24/*
25 * Check permissions for extended attribute access. This is a bit complicated
26 * because different namespaces have very different rules.
27 */
28static int
29xattr_permission(struct inode *inode, const char *name, int mask)
30{
31 /*
32 * We can never set or remove an extended attribute on a read-only
33 * filesystem or on an immutable / append-only inode.
34 */
35 if (mask & MAY_WRITE) {
36 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
37 return -EPERM;
38 }
39
40 /*
41 * No restriction for security.* and system.* from the VFS. Decision
42 * on these is left to the underlying filesystem / security module.
43 */
44 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
45 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
46 return 0;
47
48 /*
49 * The trusted.* namespace can only be accessed by privileged users.
50 */
51 if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
52 if (!capable(CAP_SYS_ADMIN))
53 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
54 return 0;
55 }
56
57 /*
58 * In the user.* namespace, only regular files and directories can have
59 * extended attributes. For sticky directories, only the owner and
60 * privileged users can write attributes.
61 */
62 if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
63 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
64 return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
65 if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
66 (mask & MAY_WRITE) && !inode_owner_or_capable(inode))
67 return -EPERM;
68 }
69
70 return inode_permission(inode, mask);
71}
72
73/**
74 * __vfs_setxattr_noperm - perform setxattr operation without performing
75 * permission checks.
76 *
77 * @dentry - object to perform setxattr on
78 * @name - xattr name to set
79 * @value - value to set @name to
80 * @size - size of @value
81 * @flags - flags to pass into filesystem operations
82 *
83 * returns the result of the internal setxattr or setsecurity operations.
84 *
85 * This function requires the caller to lock the inode's i_mutex before it
86 * is executed. It also assumes that the caller will make the appropriate
87 * permission checks.
88 */
89int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
90 const void *value, size_t size, int flags)
91{
92 struct inode *inode = dentry->d_inode;
93 int error = -EOPNOTSUPP;
94 int issec = !strncmp(name, XATTR_SECURITY_PREFIX,
95 XATTR_SECURITY_PREFIX_LEN);
96
97 if (issec)
98 inode->i_flags &= ~S_NOSEC;
99 if (inode->i_op->setxattr) {
100 error = inode->i_op->setxattr(dentry, name, value, size, flags);
101 if (!error) {
102 fsnotify_xattr(dentry);
103 security_inode_post_setxattr(dentry, name, value,
104 size, flags);
105 }
106 } else if (issec) {
107 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
108 error = security_inode_setsecurity(inode, suffix, value,
109 size, flags);
110 if (!error)
111 fsnotify_xattr(dentry);
112 }
113
114 return error;
115}
116
117
118int
119vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
120 size_t size, int flags)
121{
122 struct inode *inode = dentry->d_inode;
123 int error;
124
125 error = xattr_permission(inode, name, MAY_WRITE);
126 if (error)
127 return error;
128
129 mutex_lock(&inode->i_mutex);
130 error = security_inode_setxattr(dentry, name, value, size, flags);
131 if (error)
132 goto out;
133
134 error = __vfs_setxattr_noperm(dentry, name, value, size, flags);
135
136out:
137 mutex_unlock(&inode->i_mutex);
138 return error;
139}
140EXPORT_SYMBOL_GPL(vfs_setxattr);
141
142ssize_t
143xattr_getsecurity(struct inode *inode, const char *name, void *value,
144 size_t size)
145{
146 void *buffer = NULL;
147 ssize_t len;
148
149 if (!value || !size) {
150 len = security_inode_getsecurity(inode, name, &buffer, false);
151 goto out_noalloc;
152 }
153
154 len = security_inode_getsecurity(inode, name, &buffer, true);
155 if (len < 0)
156 return len;
157 if (size < len) {
158 len = -ERANGE;
159 goto out;
160 }
161 memcpy(value, buffer, len);
162out:
163 security_release_secctx(buffer, len);
164out_noalloc:
165 return len;
166}
167EXPORT_SYMBOL_GPL(xattr_getsecurity);
168
169ssize_t
170vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
171{
172 struct inode *inode = dentry->d_inode;
173 int error;
174
175 error = xattr_permission(inode, name, MAY_READ);
176 if (error)
177 return error;
178
179 error = security_inode_getxattr(dentry, name);
180 if (error)
181 return error;
182
183 if (!strncmp(name, XATTR_SECURITY_PREFIX,
184 XATTR_SECURITY_PREFIX_LEN)) {
185 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
186 int ret = xattr_getsecurity(inode, suffix, value, size);
187 /*
188 * Only overwrite the return value if a security module
189 * is actually active.
190 */
191 if (ret == -EOPNOTSUPP)
192 goto nolsm;
193 return ret;
194 }
195nolsm:
196 if (inode->i_op->getxattr)
197 error = inode->i_op->getxattr(dentry, name, value, size);
198 else
199 error = -EOPNOTSUPP;
200
201 return error;
202}
203EXPORT_SYMBOL_GPL(vfs_getxattr);
204
205ssize_t
206vfs_listxattr(struct dentry *d, char *list, size_t size)
207{
208 ssize_t error;
209
210 error = security_inode_listxattr(d);
211 if (error)
212 return error;
213 error = -EOPNOTSUPP;
214 if (d->d_inode->i_op->listxattr) {
215 error = d->d_inode->i_op->listxattr(d, list, size);
216 } else {
217 error = security_inode_listsecurity(d->d_inode, list, size);
218 if (size && error > size)
219 error = -ERANGE;
220 }
221 return error;
222}
223EXPORT_SYMBOL_GPL(vfs_listxattr);
224
225int
226vfs_removexattr(struct dentry *dentry, const char *name)
227{
228 struct inode *inode = dentry->d_inode;
229 int error;
230
231 if (!inode->i_op->removexattr)
232 return -EOPNOTSUPP;
233
234 error = xattr_permission(inode, name, MAY_WRITE);
235 if (error)
236 return error;
237
238 error = security_inode_removexattr(dentry, name);
239 if (error)
240 return error;
241
242 mutex_lock(&inode->i_mutex);
243 error = inode->i_op->removexattr(dentry, name);
244 mutex_unlock(&inode->i_mutex);
245
246 if (!error)
247 fsnotify_xattr(dentry);
248 return error;
249}
250EXPORT_SYMBOL_GPL(vfs_removexattr);
251
252
253/*
254 * Extended attribute SET operations
255 */
256static long
257setxattr(struct dentry *d, const char __user *name, const void __user *value,
258 size_t size, int flags)
259{
260 int error;
261 void *kvalue = NULL;
262 char kname[XATTR_NAME_MAX + 1];
263
264 if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
265 return -EINVAL;
266
267 error = strncpy_from_user(kname, name, sizeof(kname));
268 if (error == 0 || error == sizeof(kname))
269 error = -ERANGE;
270 if (error < 0)
271 return error;
272
273 if (size) {
274 if (size > XATTR_SIZE_MAX)
275 return -E2BIG;
276 kvalue = memdup_user(value, size);
277 if (IS_ERR(kvalue))
278 return PTR_ERR(kvalue);
279 }
280
281 error = vfs_setxattr(d, kname, kvalue, size, flags);
282 kfree(kvalue);
283 return error;
284}
285
286SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
287 const char __user *, name, const void __user *, value,
288 size_t, size, int, flags)
289{
290 struct path path;
291 int error;
292
293 error = user_path(pathname, &path);
294 if (error)
295 return error;
296 error = mnt_want_write(path.mnt);
297 if (!error) {
298 error = setxattr(path.dentry, name, value, size, flags);
299 mnt_drop_write(path.mnt);
300 }
301 path_put(&path);
302 return error;
303}
304
305SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
306 const char __user *, name, const void __user *, value,
307 size_t, size, int, flags)
308{
309 struct path path;
310 int error;
311
312 error = user_lpath(pathname, &path);
313 if (error)
314 return error;
315 error = mnt_want_write(path.mnt);
316 if (!error) {
317 error = setxattr(path.dentry, name, value, size, flags);
318 mnt_drop_write(path.mnt);
319 }
320 path_put(&path);
321 return error;
322}
323
324SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
325 const void __user *,value, size_t, size, int, flags)
326{
327 struct file *f;
328 struct dentry *dentry;
329 int error = -EBADF;
330
331 f = fget(fd);
332 if (!f)
333 return error;
334 dentry = f->f_path.dentry;
335 audit_inode(NULL, dentry);
336 error = mnt_want_write_file(f);
337 if (!error) {
338 error = setxattr(dentry, name, value, size, flags);
339 mnt_drop_write(f->f_path.mnt);
340 }
341 fput(f);
342 return error;
343}
344
345/*
346 * Extended attribute GET operations
347 */
348static ssize_t
349getxattr(struct dentry *d, const char __user *name, void __user *value,
350 size_t size)
351{
352 ssize_t error;
353 void *kvalue = NULL;
354 char kname[XATTR_NAME_MAX + 1];
355
356 error = strncpy_from_user(kname, name, sizeof(kname));
357 if (error == 0 || error == sizeof(kname))
358 error = -ERANGE;
359 if (error < 0)
360 return error;
361
362 if (size) {
363 if (size > XATTR_SIZE_MAX)
364 size = XATTR_SIZE_MAX;
365 kvalue = kzalloc(size, GFP_KERNEL);
366 if (!kvalue)
367 return -ENOMEM;
368 }
369
370 error = vfs_getxattr(d, kname, kvalue, size);
371 if (error > 0) {
372 if (size && copy_to_user(value, kvalue, error))
373 error = -EFAULT;
374 } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
375 /* The file system tried to returned a value bigger
376 than XATTR_SIZE_MAX bytes. Not possible. */
377 error = -E2BIG;
378 }
379 kfree(kvalue);
380 return error;
381}
382
383SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
384 const char __user *, name, void __user *, value, size_t, size)
385{
386 struct path path;
387 ssize_t error;
388
389 error = user_path(pathname, &path);
390 if (error)
391 return error;
392 error = getxattr(path.dentry, name, value, size);
393 path_put(&path);
394 return error;
395}
396
397SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
398 const char __user *, name, void __user *, value, size_t, size)
399{
400 struct path path;
401 ssize_t error;
402
403 error = user_lpath(pathname, &path);
404 if (error)
405 return error;
406 error = getxattr(path.dentry, name, value, size);
407 path_put(&path);
408 return error;
409}
410
411SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
412 void __user *, value, size_t, size)
413{
414 struct file *f;
415 ssize_t error = -EBADF;
416
417 f = fget(fd);
418 if (!f)
419 return error;
420 audit_inode(NULL, f->f_path.dentry);
421 error = getxattr(f->f_path.dentry, name, value, size);
422 fput(f);
423 return error;
424}
425
426/*
427 * Extended attribute LIST operations
428 */
429static ssize_t
430listxattr(struct dentry *d, char __user *list, size_t size)
431{
432 ssize_t error;
433 char *klist = NULL;
434
435 if (size) {
436 if (size > XATTR_LIST_MAX)
437 size = XATTR_LIST_MAX;
438 klist = kmalloc(size, GFP_KERNEL);
439 if (!klist)
440 return -ENOMEM;
441 }
442
443 error = vfs_listxattr(d, klist, size);
444 if (error > 0) {
445 if (size && copy_to_user(list, klist, error))
446 error = -EFAULT;
447 } else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
448 /* The file system tried to returned a list bigger
449 than XATTR_LIST_MAX bytes. Not possible. */
450 error = -E2BIG;
451 }
452 kfree(klist);
453 return error;
454}
455
456SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
457 size_t, size)
458{
459 struct path path;
460 ssize_t error;
461
462 error = user_path(pathname, &path);
463 if (error)
464 return error;
465 error = listxattr(path.dentry, list, size);
466 path_put(&path);
467 return error;
468}
469
470SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
471 size_t, size)
472{
473 struct path path;
474 ssize_t error;
475
476 error = user_lpath(pathname, &path);
477 if (error)
478 return error;
479 error = listxattr(path.dentry, list, size);
480 path_put(&path);
481 return error;
482}
483
484SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
485{
486 struct file *f;
487 ssize_t error = -EBADF;
488
489 f = fget(fd);
490 if (!f)
491 return error;
492 audit_inode(NULL, f->f_path.dentry);
493 error = listxattr(f->f_path.dentry, list, size);
494 fput(f);
495 return error;
496}
497
498/*
499 * Extended attribute REMOVE operations
500 */
501static long
502removexattr(struct dentry *d, const char __user *name)
503{
504 int error;
505 char kname[XATTR_NAME_MAX + 1];
506
507 error = strncpy_from_user(kname, name, sizeof(kname));
508 if (error == 0 || error == sizeof(kname))
509 error = -ERANGE;
510 if (error < 0)
511 return error;
512
513 return vfs_removexattr(d, kname);
514}
515
516SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
517 const char __user *, name)
518{
519 struct path path;
520 int error;
521
522 error = user_path(pathname, &path);
523 if (error)
524 return error;
525 error = mnt_want_write(path.mnt);
526 if (!error) {
527 error = removexattr(path.dentry, name);
528 mnt_drop_write(path.mnt);
529 }
530 path_put(&path);
531 return error;
532}
533
534SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
535 const char __user *, name)
536{
537 struct path path;
538 int error;
539
540 error = user_lpath(pathname, &path);
541 if (error)
542 return error;
543 error = mnt_want_write(path.mnt);
544 if (!error) {
545 error = removexattr(path.dentry, name);
546 mnt_drop_write(path.mnt);
547 }
548 path_put(&path);
549 return error;
550}
551
552SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
553{
554 struct file *f;
555 struct dentry *dentry;
556 int error = -EBADF;
557
558 f = fget(fd);
559 if (!f)
560 return error;
561 dentry = f->f_path.dentry;
562 audit_inode(NULL, dentry);
563 error = mnt_want_write_file(f);
564 if (!error) {
565 error = removexattr(dentry, name);
566 mnt_drop_write(f->f_path.mnt);
567 }
568 fput(f);
569 return error;
570}
571
572
573static const char *
574strcmp_prefix(const char *a, const char *a_prefix)
575{
576 while (*a_prefix && *a == *a_prefix) {
577 a++;
578 a_prefix++;
579 }
580 return *a_prefix ? NULL : a;
581}
582
583/*
584 * In order to implement different sets of xattr operations for each xattr
585 * prefix with the generic xattr API, a filesystem should create a
586 * null-terminated array of struct xattr_handler (one for each prefix) and
587 * hang a pointer to it off of the s_xattr field of the superblock.
588 *
589 * The generic_fooxattr() functions will use this list to dispatch xattr
590 * operations to the correct xattr_handler.
591 */
592#define for_each_xattr_handler(handlers, handler) \
593 for ((handler) = *(handlers)++; \
594 (handler) != NULL; \
595 (handler) = *(handlers)++)
596
597/*
598 * Find the xattr_handler with the matching prefix.
599 */
600static const struct xattr_handler *
601xattr_resolve_name(const struct xattr_handler **handlers, const char **name)
602{
603 const struct xattr_handler *handler;
604
605 if (!*name)
606 return NULL;
607
608 for_each_xattr_handler(handlers, handler) {
609 const char *n = strcmp_prefix(*name, handler->prefix);
610 if (n) {
611 *name = n;
612 break;
613 }
614 }
615 return handler;
616}
617
618/*
619 * Find the handler for the prefix and dispatch its get() operation.
620 */
621ssize_t
622generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size)
623{
624 const struct xattr_handler *handler;
625
626 handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
627 if (!handler)
628 return -EOPNOTSUPP;
629 return handler->get(dentry, name, buffer, size, handler->flags);
630}
631
632/*
633 * Combine the results of the list() operation from every xattr_handler in the
634 * list.
635 */
636ssize_t
637generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
638{
639 const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr;
640 unsigned int size = 0;
641
642 if (!buffer) {
643 for_each_xattr_handler(handlers, handler) {
644 size += handler->list(dentry, NULL, 0, NULL, 0,
645 handler->flags);
646 }
647 } else {
648 char *buf = buffer;
649
650 for_each_xattr_handler(handlers, handler) {
651 size = handler->list(dentry, buf, buffer_size,
652 NULL, 0, handler->flags);
653 if (size > buffer_size)
654 return -ERANGE;
655 buf += size;
656 buffer_size -= size;
657 }
658 size = buf - buffer;
659 }
660 return size;
661}
662
663/*
664 * Find the handler for the prefix and dispatch its set() operation.
665 */
666int
667generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
668{
669 const struct xattr_handler *handler;
670
671 if (size == 0)
672 value = ""; /* empty EA, do not remove */
673 handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
674 if (!handler)
675 return -EOPNOTSUPP;
676 return handler->set(dentry, name, value, size, flags, handler->flags);
677}
678
679/*
680 * Find the handler for the prefix and dispatch its set() operation to remove
681 * any associated extended attribute.
682 */
683int
684generic_removexattr(struct dentry *dentry, const char *name)
685{
686 const struct xattr_handler *handler;
687
688 handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
689 if (!handler)
690 return -EOPNOTSUPP;
691 return handler->set(dentry, name, NULL, 0,
692 XATTR_REPLACE, handler->flags);
693}
694
695EXPORT_SYMBOL(generic_getxattr);
696EXPORT_SYMBOL(generic_listxattr);
697EXPORT_SYMBOL(generic_setxattr);
698EXPORT_SYMBOL(generic_removexattr);