xref: /openbmc/linux/fs/posix_acl.c (revision 37bc1539)
1 /*
2  * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org>
3  *
4  * Fixes from William Schumacher incorporated on 15 March 2001.
5  *    (Reported by Charles Bertsch, <CBertsch@microtest.com>).
6  */
7 
8 /*
9  *  This file contains generic functions for manipulating
10  *  POSIX 1003.1e draft standard 17 ACLs.
11  */
12 
13 #include <linux/kernel.h>
14 #include <linux/slab.h>
15 #include <linux/atomic.h>
16 #include <linux/fs.h>
17 #include <linux/sched.h>
18 #include <linux/posix_acl.h>
19 #include <linux/posix_acl_xattr.h>
20 #include <linux/xattr.h>
21 #include <linux/export.h>
22 #include <linux/user_namespace.h>
23 
24 EXPORT_SYMBOL(posix_acl_init);
25 EXPORT_SYMBOL(posix_acl_alloc);
26 EXPORT_SYMBOL(posix_acl_valid);
27 EXPORT_SYMBOL(posix_acl_equiv_mode);
28 EXPORT_SYMBOL(posix_acl_from_mode);
29 
30 struct posix_acl *get_acl(struct inode *inode, int type)
31 {
32 	struct posix_acl *acl;
33 
34 	acl = get_cached_acl(inode, type);
35 	if (acl != ACL_NOT_CACHED)
36 		return acl;
37 
38 	if (!IS_POSIXACL(inode))
39 		return NULL;
40 
41 	/*
42 	 * A filesystem can force a ACL callback by just never filling the
43 	 * ACL cache. But normally you'd fill the cache either at inode
44 	 * instantiation time, or on the first ->get_acl call.
45 	 *
46 	 * If the filesystem doesn't have a get_acl() function at all, we'll
47 	 * just create the negative cache entry.
48 	 */
49 	if (!inode->i_op->get_acl) {
50 		set_cached_acl(inode, type, NULL);
51 		return NULL;
52 	}
53 	return inode->i_op->get_acl(inode, type);
54 }
55 EXPORT_SYMBOL(get_acl);
56 
57 /*
58  * Init a fresh posix_acl
59  */
60 void
61 posix_acl_init(struct posix_acl *acl, int count)
62 {
63 	atomic_set(&acl->a_refcount, 1);
64 	acl->a_count = count;
65 }
66 
67 /*
68  * Allocate a new ACL with the specified number of entries.
69  */
70 struct posix_acl *
71 posix_acl_alloc(int count, gfp_t flags)
72 {
73 	const size_t size = sizeof(struct posix_acl) +
74 	                    count * sizeof(struct posix_acl_entry);
75 	struct posix_acl *acl = kmalloc(size, flags);
76 	if (acl)
77 		posix_acl_init(acl, count);
78 	return acl;
79 }
80 
81 /*
82  * Clone an ACL.
83  */
84 static struct posix_acl *
85 posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
86 {
87 	struct posix_acl *clone = NULL;
88 
89 	if (acl) {
90 		int size = sizeof(struct posix_acl) + acl->a_count *
91 		           sizeof(struct posix_acl_entry);
92 		clone = kmemdup(acl, size, flags);
93 		if (clone)
94 			atomic_set(&clone->a_refcount, 1);
95 	}
96 	return clone;
97 }
98 
99 /*
100  * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
101  */
102 int
103 posix_acl_valid(const struct posix_acl *acl)
104 {
105 	const struct posix_acl_entry *pa, *pe;
106 	int state = ACL_USER_OBJ;
107 	kuid_t prev_uid = INVALID_UID;
108 	kgid_t prev_gid = INVALID_GID;
109 	int needs_mask = 0;
110 
111 	FOREACH_ACL_ENTRY(pa, acl, pe) {
112 		if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
113 			return -EINVAL;
114 		switch (pa->e_tag) {
115 			case ACL_USER_OBJ:
116 				if (state == ACL_USER_OBJ) {
117 					state = ACL_USER;
118 					break;
119 				}
120 				return -EINVAL;
121 
122 			case ACL_USER:
123 				if (state != ACL_USER)
124 					return -EINVAL;
125 				if (!uid_valid(pa->e_uid))
126 					return -EINVAL;
127 				if (uid_valid(prev_uid) &&
128 				    uid_lte(pa->e_uid, prev_uid))
129 					return -EINVAL;
130 				prev_uid = pa->e_uid;
131 				needs_mask = 1;
132 				break;
133 
134 			case ACL_GROUP_OBJ:
135 				if (state == ACL_USER) {
136 					state = ACL_GROUP;
137 					break;
138 				}
139 				return -EINVAL;
140 
141 			case ACL_GROUP:
142 				if (state != ACL_GROUP)
143 					return -EINVAL;
144 				if (!gid_valid(pa->e_gid))
145 					return -EINVAL;
146 				if (gid_valid(prev_gid) &&
147 				    gid_lte(pa->e_gid, prev_gid))
148 					return -EINVAL;
149 				prev_gid = pa->e_gid;
150 				needs_mask = 1;
151 				break;
152 
153 			case ACL_MASK:
154 				if (state != ACL_GROUP)
155 					return -EINVAL;
156 				state = ACL_OTHER;
157 				break;
158 
159 			case ACL_OTHER:
160 				if (state == ACL_OTHER ||
161 				    (state == ACL_GROUP && !needs_mask)) {
162 					state = 0;
163 					break;
164 				}
165 				return -EINVAL;
166 
167 			default:
168 				return -EINVAL;
169 		}
170 	}
171 	if (state == 0)
172 		return 0;
173 	return -EINVAL;
174 }
175 
176 /*
177  * Returns 0 if the acl can be exactly represented in the traditional
178  * file mode permission bits, or else 1. Returns -E... on error.
179  */
180 int
181 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
182 {
183 	const struct posix_acl_entry *pa, *pe;
184 	umode_t mode = 0;
185 	int not_equiv = 0;
186 
187 	FOREACH_ACL_ENTRY(pa, acl, pe) {
188 		switch (pa->e_tag) {
189 			case ACL_USER_OBJ:
190 				mode |= (pa->e_perm & S_IRWXO) << 6;
191 				break;
192 			case ACL_GROUP_OBJ:
193 				mode |= (pa->e_perm & S_IRWXO) << 3;
194 				break;
195 			case ACL_OTHER:
196 				mode |= pa->e_perm & S_IRWXO;
197 				break;
198 			case ACL_MASK:
199 				mode = (mode & ~S_IRWXG) |
200 				       ((pa->e_perm & S_IRWXO) << 3);
201 				not_equiv = 1;
202 				break;
203 			case ACL_USER:
204 			case ACL_GROUP:
205 				not_equiv = 1;
206 				break;
207 			default:
208 				return -EINVAL;
209 		}
210 	}
211         if (mode_p)
212                 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
213         return not_equiv;
214 }
215 
216 /*
217  * Create an ACL representing the file mode permission bits of an inode.
218  */
219 struct posix_acl *
220 posix_acl_from_mode(umode_t mode, gfp_t flags)
221 {
222 	struct posix_acl *acl = posix_acl_alloc(3, flags);
223 	if (!acl)
224 		return ERR_PTR(-ENOMEM);
225 
226 	acl->a_entries[0].e_tag  = ACL_USER_OBJ;
227 	acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
228 
229 	acl->a_entries[1].e_tag  = ACL_GROUP_OBJ;
230 	acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
231 
232 	acl->a_entries[2].e_tag  = ACL_OTHER;
233 	acl->a_entries[2].e_perm = (mode & S_IRWXO);
234 	return acl;
235 }
236 
237 /*
238  * Return 0 if current is granted want access to the inode
239  * by the acl. Returns -E... otherwise.
240  */
241 int
242 posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
243 {
244 	const struct posix_acl_entry *pa, *pe, *mask_obj;
245 	int found = 0;
246 
247 	want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
248 
249 	FOREACH_ACL_ENTRY(pa, acl, pe) {
250                 switch(pa->e_tag) {
251                         case ACL_USER_OBJ:
252 				/* (May have been checked already) */
253 				if (uid_eq(inode->i_uid, current_fsuid()))
254                                         goto check_perm;
255                                 break;
256                         case ACL_USER:
257 				if (uid_eq(pa->e_uid, current_fsuid()))
258                                         goto mask;
259 				break;
260                         case ACL_GROUP_OBJ:
261                                 if (in_group_p(inode->i_gid)) {
262 					found = 1;
263 					if ((pa->e_perm & want) == want)
264 						goto mask;
265                                 }
266 				break;
267                         case ACL_GROUP:
268 				if (in_group_p(pa->e_gid)) {
269 					found = 1;
270 					if ((pa->e_perm & want) == want)
271 						goto mask;
272                                 }
273                                 break;
274                         case ACL_MASK:
275                                 break;
276                         case ACL_OTHER:
277 				if (found)
278 					return -EACCES;
279 				else
280 					goto check_perm;
281 			default:
282 				return -EIO;
283                 }
284         }
285 	return -EIO;
286 
287 mask:
288 	for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
289 		if (mask_obj->e_tag == ACL_MASK) {
290 			if ((pa->e_perm & mask_obj->e_perm & want) == want)
291 				return 0;
292 			return -EACCES;
293 		}
294 	}
295 
296 check_perm:
297 	if ((pa->e_perm & want) == want)
298 		return 0;
299 	return -EACCES;
300 }
301 
302 /*
303  * Modify acl when creating a new inode. The caller must ensure the acl is
304  * only referenced once.
305  *
306  * mode_p initially must contain the mode parameter to the open() / creat()
307  * system calls. All permissions that are not granted by the acl are removed.
308  * The permissions in the acl are changed to reflect the mode_p parameter.
309  */
310 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
311 {
312 	struct posix_acl_entry *pa, *pe;
313 	struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
314 	umode_t mode = *mode_p;
315 	int not_equiv = 0;
316 
317 	/* assert(atomic_read(acl->a_refcount) == 1); */
318 
319 	FOREACH_ACL_ENTRY(pa, acl, pe) {
320                 switch(pa->e_tag) {
321                         case ACL_USER_OBJ:
322 				pa->e_perm &= (mode >> 6) | ~S_IRWXO;
323 				mode &= (pa->e_perm << 6) | ~S_IRWXU;
324 				break;
325 
326 			case ACL_USER:
327 			case ACL_GROUP:
328 				not_equiv = 1;
329 				break;
330 
331                         case ACL_GROUP_OBJ:
332 				group_obj = pa;
333                                 break;
334 
335                         case ACL_OTHER:
336 				pa->e_perm &= mode | ~S_IRWXO;
337 				mode &= pa->e_perm | ~S_IRWXO;
338                                 break;
339 
340                         case ACL_MASK:
341 				mask_obj = pa;
342 				not_equiv = 1;
343                                 break;
344 
345 			default:
346 				return -EIO;
347                 }
348         }
349 
350 	if (mask_obj) {
351 		mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
352 		mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
353 	} else {
354 		if (!group_obj)
355 			return -EIO;
356 		group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
357 		mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
358 	}
359 
360 	*mode_p = (*mode_p & ~S_IRWXUGO) | mode;
361         return not_equiv;
362 }
363 
364 /*
365  * Modify the ACL for the chmod syscall.
366  */
367 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
368 {
369 	struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
370 	struct posix_acl_entry *pa, *pe;
371 
372 	/* assert(atomic_read(acl->a_refcount) == 1); */
373 
374 	FOREACH_ACL_ENTRY(pa, acl, pe) {
375 		switch(pa->e_tag) {
376 			case ACL_USER_OBJ:
377 				pa->e_perm = (mode & S_IRWXU) >> 6;
378 				break;
379 
380 			case ACL_USER:
381 			case ACL_GROUP:
382 				break;
383 
384 			case ACL_GROUP_OBJ:
385 				group_obj = pa;
386 				break;
387 
388 			case ACL_MASK:
389 				mask_obj = pa;
390 				break;
391 
392 			case ACL_OTHER:
393 				pa->e_perm = (mode & S_IRWXO);
394 				break;
395 
396 			default:
397 				return -EIO;
398 		}
399 	}
400 
401 	if (mask_obj) {
402 		mask_obj->e_perm = (mode & S_IRWXG) >> 3;
403 	} else {
404 		if (!group_obj)
405 			return -EIO;
406 		group_obj->e_perm = (mode & S_IRWXG) >> 3;
407 	}
408 
409 	return 0;
410 }
411 
412 int
413 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
414 {
415 	struct posix_acl *clone = posix_acl_clone(*acl, gfp);
416 	int err = -ENOMEM;
417 	if (clone) {
418 		err = posix_acl_create_masq(clone, mode_p);
419 		if (err < 0) {
420 			posix_acl_release(clone);
421 			clone = NULL;
422 		}
423 	}
424 	posix_acl_release(*acl);
425 	*acl = clone;
426 	return err;
427 }
428 EXPORT_SYMBOL(__posix_acl_create);
429 
430 int
431 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
432 {
433 	struct posix_acl *clone = posix_acl_clone(*acl, gfp);
434 	int err = -ENOMEM;
435 	if (clone) {
436 		err = __posix_acl_chmod_masq(clone, mode);
437 		if (err) {
438 			posix_acl_release(clone);
439 			clone = NULL;
440 		}
441 	}
442 	posix_acl_release(*acl);
443 	*acl = clone;
444 	return err;
445 }
446 EXPORT_SYMBOL(__posix_acl_chmod);
447 
448 int
449 posix_acl_chmod(struct inode *inode, umode_t mode)
450 {
451 	struct posix_acl *acl;
452 	int ret = 0;
453 
454 	if (!IS_POSIXACL(inode))
455 		return 0;
456 	if (!inode->i_op->set_acl)
457 		return -EOPNOTSUPP;
458 
459 	acl = get_acl(inode, ACL_TYPE_ACCESS);
460 	if (IS_ERR_OR_NULL(acl))
461 		return PTR_ERR(acl);
462 
463 	ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
464 	if (ret)
465 		return ret;
466 	ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
467 	posix_acl_release(acl);
468 	return ret;
469 }
470 EXPORT_SYMBOL(posix_acl_chmod);
471 
472 int
473 posix_acl_create(struct inode *dir, umode_t *mode,
474 		struct posix_acl **default_acl, struct posix_acl **acl)
475 {
476 	struct posix_acl *p;
477 	int ret;
478 
479 	if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
480 		goto no_acl;
481 
482 	p = get_acl(dir, ACL_TYPE_DEFAULT);
483 	if (IS_ERR(p))
484 		return PTR_ERR(p);
485 
486 	if (!p) {
487 		*mode &= ~current_umask();
488 		goto no_acl;
489 	}
490 
491 	*acl = posix_acl_clone(p, GFP_NOFS);
492 	if (!*acl)
493 		return -ENOMEM;
494 
495 	ret = posix_acl_create_masq(*acl, mode);
496 	if (ret < 0) {
497 		posix_acl_release(*acl);
498 		return -ENOMEM;
499 	}
500 
501 	if (ret == 0) {
502 		posix_acl_release(*acl);
503 		*acl = NULL;
504 	}
505 
506 	if (!S_ISDIR(*mode)) {
507 		posix_acl_release(p);
508 		*default_acl = NULL;
509 	} else {
510 		*default_acl = p;
511 	}
512 	return 0;
513 
514 no_acl:
515 	*default_acl = NULL;
516 	*acl = NULL;
517 	return 0;
518 }
519 EXPORT_SYMBOL_GPL(posix_acl_create);
520 
521 /*
522  * Fix up the uids and gids in posix acl extended attributes in place.
523  */
524 static void posix_acl_fix_xattr_userns(
525 	struct user_namespace *to, struct user_namespace *from,
526 	void *value, size_t size)
527 {
528 	posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
529 	posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
530 	int count;
531 	kuid_t uid;
532 	kgid_t gid;
533 
534 	if (!value)
535 		return;
536 	if (size < sizeof(posix_acl_xattr_header))
537 		return;
538 	if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
539 		return;
540 
541 	count = posix_acl_xattr_count(size);
542 	if (count < 0)
543 		return;
544 	if (count == 0)
545 		return;
546 
547 	for (end = entry + count; entry != end; entry++) {
548 		switch(le16_to_cpu(entry->e_tag)) {
549 		case ACL_USER:
550 			uid = make_kuid(from, le32_to_cpu(entry->e_id));
551 			entry->e_id = cpu_to_le32(from_kuid(to, uid));
552 			break;
553 		case ACL_GROUP:
554 			gid = make_kgid(from, le32_to_cpu(entry->e_id));
555 			entry->e_id = cpu_to_le32(from_kgid(to, gid));
556 			break;
557 		default:
558 			break;
559 		}
560 	}
561 }
562 
563 void posix_acl_fix_xattr_from_user(void *value, size_t size)
564 {
565 	struct user_namespace *user_ns = current_user_ns();
566 	if (user_ns == &init_user_ns)
567 		return;
568 	posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
569 }
570 
571 void posix_acl_fix_xattr_to_user(void *value, size_t size)
572 {
573 	struct user_namespace *user_ns = current_user_ns();
574 	if (user_ns == &init_user_ns)
575 		return;
576 	posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
577 }
578 
579 /*
580  * Convert from extended attribute to in-memory representation.
581  */
582 struct posix_acl *
583 posix_acl_from_xattr(struct user_namespace *user_ns,
584 		     const void *value, size_t size)
585 {
586 	posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
587 	posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
588 	int count;
589 	struct posix_acl *acl;
590 	struct posix_acl_entry *acl_e;
591 
592 	if (!value)
593 		return NULL;
594 	if (size < sizeof(posix_acl_xattr_header))
595 		 return ERR_PTR(-EINVAL);
596 	if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
597 		return ERR_PTR(-EOPNOTSUPP);
598 
599 	count = posix_acl_xattr_count(size);
600 	if (count < 0)
601 		return ERR_PTR(-EINVAL);
602 	if (count == 0)
603 		return NULL;
604 
605 	acl = posix_acl_alloc(count, GFP_NOFS);
606 	if (!acl)
607 		return ERR_PTR(-ENOMEM);
608 	acl_e = acl->a_entries;
609 
610 	for (end = entry + count; entry != end; acl_e++, entry++) {
611 		acl_e->e_tag  = le16_to_cpu(entry->e_tag);
612 		acl_e->e_perm = le16_to_cpu(entry->e_perm);
613 
614 		switch(acl_e->e_tag) {
615 			case ACL_USER_OBJ:
616 			case ACL_GROUP_OBJ:
617 			case ACL_MASK:
618 			case ACL_OTHER:
619 				break;
620 
621 			case ACL_USER:
622 				acl_e->e_uid =
623 					make_kuid(user_ns,
624 						  le32_to_cpu(entry->e_id));
625 				if (!uid_valid(acl_e->e_uid))
626 					goto fail;
627 				break;
628 			case ACL_GROUP:
629 				acl_e->e_gid =
630 					make_kgid(user_ns,
631 						  le32_to_cpu(entry->e_id));
632 				if (!gid_valid(acl_e->e_gid))
633 					goto fail;
634 				break;
635 
636 			default:
637 				goto fail;
638 		}
639 	}
640 	return acl;
641 
642 fail:
643 	posix_acl_release(acl);
644 	return ERR_PTR(-EINVAL);
645 }
646 EXPORT_SYMBOL (posix_acl_from_xattr);
647 
648 /*
649  * Convert from in-memory to extended attribute representation.
650  */
651 int
652 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
653 		   void *buffer, size_t size)
654 {
655 	posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
656 	posix_acl_xattr_entry *ext_entry = ext_acl->a_entries;
657 	int real_size, n;
658 
659 	real_size = posix_acl_xattr_size(acl->a_count);
660 	if (!buffer)
661 		return real_size;
662 	if (real_size > size)
663 		return -ERANGE;
664 
665 	ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
666 
667 	for (n=0; n < acl->a_count; n++, ext_entry++) {
668 		const struct posix_acl_entry *acl_e = &acl->a_entries[n];
669 		ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
670 		ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
671 		switch(acl_e->e_tag) {
672 		case ACL_USER:
673 			ext_entry->e_id =
674 				cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
675 			break;
676 		case ACL_GROUP:
677 			ext_entry->e_id =
678 				cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
679 			break;
680 		default:
681 			ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
682 			break;
683 		}
684 	}
685 	return real_size;
686 }
687 EXPORT_SYMBOL (posix_acl_to_xattr);
688 
689 static int
690 posix_acl_xattr_get(struct dentry *dentry, const char *name,
691 		void *value, size_t size, int type)
692 {
693 	struct posix_acl *acl;
694 	int error;
695 
696 	if (!IS_POSIXACL(dentry->d_inode))
697 		return -EOPNOTSUPP;
698 	if (S_ISLNK(dentry->d_inode->i_mode))
699 		return -EOPNOTSUPP;
700 
701 	acl = get_acl(dentry->d_inode, type);
702 	if (IS_ERR(acl))
703 		return PTR_ERR(acl);
704 	if (acl == NULL)
705 		return -ENODATA;
706 
707 	error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
708 	posix_acl_release(acl);
709 
710 	return error;
711 }
712 
713 static int
714 posix_acl_xattr_set(struct dentry *dentry, const char *name,
715 		const void *value, size_t size, int flags, int type)
716 {
717 	struct inode *inode = dentry->d_inode;
718 	struct posix_acl *acl = NULL;
719 	int ret;
720 
721 	if (!IS_POSIXACL(inode))
722 		return -EOPNOTSUPP;
723 	if (!inode->i_op->set_acl)
724 		return -EOPNOTSUPP;
725 
726 	if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
727 		return value ? -EACCES : 0;
728 	if (!inode_owner_or_capable(inode))
729 		return -EPERM;
730 
731 	if (value) {
732 		acl = posix_acl_from_xattr(&init_user_ns, value, size);
733 		if (IS_ERR(acl))
734 			return PTR_ERR(acl);
735 
736 		if (acl) {
737 			ret = posix_acl_valid(acl);
738 			if (ret)
739 				goto out;
740 		}
741 	}
742 
743 	ret = inode->i_op->set_acl(inode, acl, type);
744 out:
745 	posix_acl_release(acl);
746 	return ret;
747 }
748 
749 static size_t
750 posix_acl_xattr_list(struct dentry *dentry, char *list, size_t list_size,
751 		const char *name, size_t name_len, int type)
752 {
753 	const char *xname;
754 	size_t size;
755 
756 	if (!IS_POSIXACL(dentry->d_inode))
757 		return -EOPNOTSUPP;
758 	if (S_ISLNK(dentry->d_inode->i_mode))
759 		return -EOPNOTSUPP;
760 
761 	if (type == ACL_TYPE_ACCESS)
762 		xname = POSIX_ACL_XATTR_ACCESS;
763 	else
764 		xname = POSIX_ACL_XATTR_DEFAULT;
765 
766 	size = strlen(xname) + 1;
767 	if (list && size <= list_size)
768 		memcpy(list, xname, size);
769 	return size;
770 }
771 
772 const struct xattr_handler posix_acl_access_xattr_handler = {
773 	.prefix = POSIX_ACL_XATTR_ACCESS,
774 	.flags = ACL_TYPE_ACCESS,
775 	.list = posix_acl_xattr_list,
776 	.get = posix_acl_xattr_get,
777 	.set = posix_acl_xattr_set,
778 };
779 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
780 
781 const struct xattr_handler posix_acl_default_xattr_handler = {
782 	.prefix = POSIX_ACL_XATTR_DEFAULT,
783 	.flags = ACL_TYPE_DEFAULT,
784 	.list = posix_acl_xattr_list,
785 	.get = posix_acl_xattr_get,
786 	.set = posix_acl_xattr_set,
787 };
788 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
789