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