1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org>
4 *
5 * Fixes from William Schumacher incorporated on 15 March 2001.
6 * (Reported by Charles Bertsch, <CBertsch@microtest.com>).
7 */
8
9 /*
10 * This file contains generic functions for manipulating
11 * POSIX 1003.1e draft standard 17 ACLs.
12 */
13
14 #include <linux/kernel.h>
15 #include <linux/slab.h>
16 #include <linux/atomic.h>
17 #include <linux/fs.h>
18 #include <linux/sched.h>
19 #include <linux/cred.h>
20 #include <linux/posix_acl.h>
21 #include <linux/posix_acl_xattr.h>
22 #include <linux/xattr.h>
23 #include <linux/export.h>
24 #include <linux/user_namespace.h>
25
acl_by_type(struct inode * inode,int type)26 static struct posix_acl **acl_by_type(struct inode *inode, int type)
27 {
28 switch (type) {
29 case ACL_TYPE_ACCESS:
30 return &inode->i_acl;
31 case ACL_TYPE_DEFAULT:
32 return &inode->i_default_acl;
33 default:
34 BUG();
35 }
36 }
37
get_cached_acl(struct inode * inode,int type)38 struct posix_acl *get_cached_acl(struct inode *inode, int type)
39 {
40 struct posix_acl **p = acl_by_type(inode, type);
41 struct posix_acl *acl;
42
43 for (;;) {
44 rcu_read_lock();
45 acl = rcu_dereference(*p);
46 if (!acl || is_uncached_acl(acl) ||
47 refcount_inc_not_zero(&acl->a_refcount))
48 break;
49 rcu_read_unlock();
50 cpu_relax();
51 }
52 rcu_read_unlock();
53 return acl;
54 }
55 EXPORT_SYMBOL(get_cached_acl);
56
get_cached_acl_rcu(struct inode * inode,int type)57 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
58 {
59 return rcu_dereference(*acl_by_type(inode, type));
60 }
61 EXPORT_SYMBOL(get_cached_acl_rcu);
62
set_cached_acl(struct inode * inode,int type,struct posix_acl * acl)63 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
64 {
65 struct posix_acl **p = acl_by_type(inode, type);
66 struct posix_acl *old;
67
68 old = xchg(p, posix_acl_dup(acl));
69 if (!is_uncached_acl(old))
70 posix_acl_release(old);
71 }
72 EXPORT_SYMBOL(set_cached_acl);
73
__forget_cached_acl(struct posix_acl ** p)74 static void __forget_cached_acl(struct posix_acl **p)
75 {
76 struct posix_acl *old;
77
78 old = xchg(p, ACL_NOT_CACHED);
79 if (!is_uncached_acl(old))
80 posix_acl_release(old);
81 }
82
forget_cached_acl(struct inode * inode,int type)83 void forget_cached_acl(struct inode *inode, int type)
84 {
85 __forget_cached_acl(acl_by_type(inode, type));
86 }
87 EXPORT_SYMBOL(forget_cached_acl);
88
forget_all_cached_acls(struct inode * inode)89 void forget_all_cached_acls(struct inode *inode)
90 {
91 __forget_cached_acl(&inode->i_acl);
92 __forget_cached_acl(&inode->i_default_acl);
93 }
94 EXPORT_SYMBOL(forget_all_cached_acls);
95
get_acl(struct inode * inode,int type)96 struct posix_acl *get_acl(struct inode *inode, int type)
97 {
98 void *sentinel;
99 struct posix_acl **p;
100 struct posix_acl *acl;
101
102 /*
103 * The sentinel is used to detect when another operation like
104 * set_cached_acl() or forget_cached_acl() races with get_acl().
105 * It is guaranteed that is_uncached_acl(sentinel) is true.
106 */
107
108 acl = get_cached_acl(inode, type);
109 if (!is_uncached_acl(acl))
110 return acl;
111
112 if (!IS_POSIXACL(inode))
113 return NULL;
114
115 sentinel = uncached_acl_sentinel(current);
116 p = acl_by_type(inode, type);
117
118 /*
119 * If the ACL isn't being read yet, set our sentinel. Otherwise, the
120 * current value of the ACL will not be ACL_NOT_CACHED and so our own
121 * sentinel will not be set; another task will update the cache. We
122 * could wait for that other task to complete its job, but it's easier
123 * to just call ->get_acl to fetch the ACL ourself. (This is going to
124 * be an unlikely race.)
125 */
126 if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED)
127 /* fall through */ ;
128
129 /*
130 * Normally, the ACL returned by ->get_acl will be cached.
131 * A filesystem can prevent that by calling
132 * forget_cached_acl(inode, type) in ->get_acl.
133 *
134 * If the filesystem doesn't have a get_acl() function at all, we'll
135 * just create the negative cache entry.
136 */
137 if (!inode->i_op->get_acl) {
138 set_cached_acl(inode, type, NULL);
139 return NULL;
140 }
141 acl = inode->i_op->get_acl(inode, type);
142
143 if (IS_ERR(acl)) {
144 /*
145 * Remove our sentinel so that we don't block future attempts
146 * to cache the ACL.
147 */
148 cmpxchg(p, sentinel, ACL_NOT_CACHED);
149 return acl;
150 }
151
152 /*
153 * Cache the result, but only if our sentinel is still in place.
154 */
155 posix_acl_dup(acl);
156 if (unlikely(cmpxchg(p, sentinel, acl) != sentinel))
157 posix_acl_release(acl);
158 return acl;
159 }
160 EXPORT_SYMBOL(get_acl);
161
162 /*
163 * Init a fresh posix_acl
164 */
165 void
posix_acl_init(struct posix_acl * acl,int count)166 posix_acl_init(struct posix_acl *acl, int count)
167 {
168 refcount_set(&acl->a_refcount, 1);
169 acl->a_count = count;
170 }
171 EXPORT_SYMBOL(posix_acl_init);
172
173 /*
174 * Allocate a new ACL with the specified number of entries.
175 */
176 struct posix_acl *
posix_acl_alloc(int count,gfp_t flags)177 posix_acl_alloc(int count, gfp_t flags)
178 {
179 const size_t size = sizeof(struct posix_acl) +
180 count * sizeof(struct posix_acl_entry);
181 struct posix_acl *acl = kmalloc(size, flags);
182 if (acl)
183 posix_acl_init(acl, count);
184 return acl;
185 }
186 EXPORT_SYMBOL(posix_acl_alloc);
187
188 /*
189 * Clone an ACL.
190 */
191 static struct posix_acl *
posix_acl_clone(const struct posix_acl * acl,gfp_t flags)192 posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
193 {
194 struct posix_acl *clone = NULL;
195
196 if (acl) {
197 int size = sizeof(struct posix_acl) + acl->a_count *
198 sizeof(struct posix_acl_entry);
199 clone = kmemdup(acl, size, flags);
200 if (clone)
201 refcount_set(&clone->a_refcount, 1);
202 }
203 return clone;
204 }
205
206 /*
207 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
208 */
209 int
posix_acl_valid(struct user_namespace * user_ns,const struct posix_acl * acl)210 posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl)
211 {
212 const struct posix_acl_entry *pa, *pe;
213 int state = ACL_USER_OBJ;
214 int needs_mask = 0;
215
216 FOREACH_ACL_ENTRY(pa, acl, pe) {
217 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
218 return -EINVAL;
219 switch (pa->e_tag) {
220 case ACL_USER_OBJ:
221 if (state == ACL_USER_OBJ) {
222 state = ACL_USER;
223 break;
224 }
225 return -EINVAL;
226
227 case ACL_USER:
228 if (state != ACL_USER)
229 return -EINVAL;
230 if (!kuid_has_mapping(user_ns, pa->e_uid))
231 return -EINVAL;
232 needs_mask = 1;
233 break;
234
235 case ACL_GROUP_OBJ:
236 if (state == ACL_USER) {
237 state = ACL_GROUP;
238 break;
239 }
240 return -EINVAL;
241
242 case ACL_GROUP:
243 if (state != ACL_GROUP)
244 return -EINVAL;
245 if (!kgid_has_mapping(user_ns, pa->e_gid))
246 return -EINVAL;
247 needs_mask = 1;
248 break;
249
250 case ACL_MASK:
251 if (state != ACL_GROUP)
252 return -EINVAL;
253 state = ACL_OTHER;
254 break;
255
256 case ACL_OTHER:
257 if (state == ACL_OTHER ||
258 (state == ACL_GROUP && !needs_mask)) {
259 state = 0;
260 break;
261 }
262 return -EINVAL;
263
264 default:
265 return -EINVAL;
266 }
267 }
268 if (state == 0)
269 return 0;
270 return -EINVAL;
271 }
272 EXPORT_SYMBOL(posix_acl_valid);
273
274 /*
275 * Returns 0 if the acl can be exactly represented in the traditional
276 * file mode permission bits, or else 1. Returns -E... on error.
277 */
278 int
posix_acl_equiv_mode(const struct posix_acl * acl,umode_t * mode_p)279 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
280 {
281 const struct posix_acl_entry *pa, *pe;
282 umode_t mode = 0;
283 int not_equiv = 0;
284
285 /*
286 * A null ACL can always be presented as mode bits.
287 */
288 if (!acl)
289 return 0;
290
291 FOREACH_ACL_ENTRY(pa, acl, pe) {
292 switch (pa->e_tag) {
293 case ACL_USER_OBJ:
294 mode |= (pa->e_perm & S_IRWXO) << 6;
295 break;
296 case ACL_GROUP_OBJ:
297 mode |= (pa->e_perm & S_IRWXO) << 3;
298 break;
299 case ACL_OTHER:
300 mode |= pa->e_perm & S_IRWXO;
301 break;
302 case ACL_MASK:
303 mode = (mode & ~S_IRWXG) |
304 ((pa->e_perm & S_IRWXO) << 3);
305 not_equiv = 1;
306 break;
307 case ACL_USER:
308 case ACL_GROUP:
309 not_equiv = 1;
310 break;
311 default:
312 return -EINVAL;
313 }
314 }
315 if (mode_p)
316 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
317 return not_equiv;
318 }
319 EXPORT_SYMBOL(posix_acl_equiv_mode);
320
321 /*
322 * Create an ACL representing the file mode permission bits of an inode.
323 */
324 struct posix_acl *
posix_acl_from_mode(umode_t mode,gfp_t flags)325 posix_acl_from_mode(umode_t mode, gfp_t flags)
326 {
327 struct posix_acl *acl = posix_acl_alloc(3, flags);
328 if (!acl)
329 return ERR_PTR(-ENOMEM);
330
331 acl->a_entries[0].e_tag = ACL_USER_OBJ;
332 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
333
334 acl->a_entries[1].e_tag = ACL_GROUP_OBJ;
335 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
336
337 acl->a_entries[2].e_tag = ACL_OTHER;
338 acl->a_entries[2].e_perm = (mode & S_IRWXO);
339 return acl;
340 }
341 EXPORT_SYMBOL(posix_acl_from_mode);
342
343 /*
344 * Return 0 if current is granted want access to the inode
345 * by the acl. Returns -E... otherwise.
346 */
347 int
posix_acl_permission(struct inode * inode,const struct posix_acl * acl,int want)348 posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
349 {
350 const struct posix_acl_entry *pa, *pe, *mask_obj;
351 int found = 0;
352
353 want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
354
355 FOREACH_ACL_ENTRY(pa, acl, pe) {
356 switch(pa->e_tag) {
357 case ACL_USER_OBJ:
358 /* (May have been checked already) */
359 if (uid_eq(inode->i_uid, current_fsuid()))
360 goto check_perm;
361 break;
362 case ACL_USER:
363 if (uid_eq(pa->e_uid, current_fsuid()))
364 goto mask;
365 break;
366 case ACL_GROUP_OBJ:
367 if (in_group_p(inode->i_gid)) {
368 found = 1;
369 if ((pa->e_perm & want) == want)
370 goto mask;
371 }
372 break;
373 case ACL_GROUP:
374 if (in_group_p(pa->e_gid)) {
375 found = 1;
376 if ((pa->e_perm & want) == want)
377 goto mask;
378 }
379 break;
380 case ACL_MASK:
381 break;
382 case ACL_OTHER:
383 if (found)
384 return -EACCES;
385 else
386 goto check_perm;
387 default:
388 return -EIO;
389 }
390 }
391 return -EIO;
392
393 mask:
394 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
395 if (mask_obj->e_tag == ACL_MASK) {
396 if ((pa->e_perm & mask_obj->e_perm & want) == want)
397 return 0;
398 return -EACCES;
399 }
400 }
401
402 check_perm:
403 if ((pa->e_perm & want) == want)
404 return 0;
405 return -EACCES;
406 }
407
408 /*
409 * Modify acl when creating a new inode. The caller must ensure the acl is
410 * only referenced once.
411 *
412 * mode_p initially must contain the mode parameter to the open() / creat()
413 * system calls. All permissions that are not granted by the acl are removed.
414 * The permissions in the acl are changed to reflect the mode_p parameter.
415 */
posix_acl_create_masq(struct posix_acl * acl,umode_t * mode_p)416 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
417 {
418 struct posix_acl_entry *pa, *pe;
419 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
420 umode_t mode = *mode_p;
421 int not_equiv = 0;
422
423 /* assert(atomic_read(acl->a_refcount) == 1); */
424
425 FOREACH_ACL_ENTRY(pa, acl, pe) {
426 switch(pa->e_tag) {
427 case ACL_USER_OBJ:
428 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
429 mode &= (pa->e_perm << 6) | ~S_IRWXU;
430 break;
431
432 case ACL_USER:
433 case ACL_GROUP:
434 not_equiv = 1;
435 break;
436
437 case ACL_GROUP_OBJ:
438 group_obj = pa;
439 break;
440
441 case ACL_OTHER:
442 pa->e_perm &= mode | ~S_IRWXO;
443 mode &= pa->e_perm | ~S_IRWXO;
444 break;
445
446 case ACL_MASK:
447 mask_obj = pa;
448 not_equiv = 1;
449 break;
450
451 default:
452 return -EIO;
453 }
454 }
455
456 if (mask_obj) {
457 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
458 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
459 } else {
460 if (!group_obj)
461 return -EIO;
462 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
463 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
464 }
465
466 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
467 return not_equiv;
468 }
469
470 /*
471 * Modify the ACL for the chmod syscall.
472 */
__posix_acl_chmod_masq(struct posix_acl * acl,umode_t mode)473 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
474 {
475 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
476 struct posix_acl_entry *pa, *pe;
477
478 /* assert(atomic_read(acl->a_refcount) == 1); */
479
480 FOREACH_ACL_ENTRY(pa, acl, pe) {
481 switch(pa->e_tag) {
482 case ACL_USER_OBJ:
483 pa->e_perm = (mode & S_IRWXU) >> 6;
484 break;
485
486 case ACL_USER:
487 case ACL_GROUP:
488 break;
489
490 case ACL_GROUP_OBJ:
491 group_obj = pa;
492 break;
493
494 case ACL_MASK:
495 mask_obj = pa;
496 break;
497
498 case ACL_OTHER:
499 pa->e_perm = (mode & S_IRWXO);
500 break;
501
502 default:
503 return -EIO;
504 }
505 }
506
507 if (mask_obj) {
508 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
509 } else {
510 if (!group_obj)
511 return -EIO;
512 group_obj->e_perm = (mode & S_IRWXG) >> 3;
513 }
514
515 return 0;
516 }
517
518 int
__posix_acl_create(struct posix_acl ** acl,gfp_t gfp,umode_t * mode_p)519 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
520 {
521 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
522 int err = -ENOMEM;
523 if (clone) {
524 err = posix_acl_create_masq(clone, mode_p);
525 if (err < 0) {
526 posix_acl_release(clone);
527 clone = NULL;
528 }
529 }
530 posix_acl_release(*acl);
531 *acl = clone;
532 return err;
533 }
534 EXPORT_SYMBOL(__posix_acl_create);
535
536 int
__posix_acl_chmod(struct posix_acl ** acl,gfp_t gfp,umode_t mode)537 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
538 {
539 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
540 int err = -ENOMEM;
541 if (clone) {
542 err = __posix_acl_chmod_masq(clone, mode);
543 if (err) {
544 posix_acl_release(clone);
545 clone = NULL;
546 }
547 }
548 posix_acl_release(*acl);
549 *acl = clone;
550 return err;
551 }
552 EXPORT_SYMBOL(__posix_acl_chmod);
553
554 int
posix_acl_chmod(struct inode * inode,umode_t mode)555 posix_acl_chmod(struct inode *inode, umode_t mode)
556 {
557 struct posix_acl *acl;
558 int ret = 0;
559
560 if (!IS_POSIXACL(inode))
561 return 0;
562 if (!inode->i_op->set_acl)
563 return -EOPNOTSUPP;
564
565 acl = get_acl(inode, ACL_TYPE_ACCESS);
566 if (IS_ERR_OR_NULL(acl)) {
567 if (acl == ERR_PTR(-EOPNOTSUPP))
568 return 0;
569 return PTR_ERR(acl);
570 }
571
572 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
573 if (ret)
574 return ret;
575 ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
576 posix_acl_release(acl);
577 return ret;
578 }
579 EXPORT_SYMBOL(posix_acl_chmod);
580
581 int
posix_acl_create(struct inode * dir,umode_t * mode,struct posix_acl ** default_acl,struct posix_acl ** acl)582 posix_acl_create(struct inode *dir, umode_t *mode,
583 struct posix_acl **default_acl, struct posix_acl **acl)
584 {
585 struct posix_acl *p;
586 struct posix_acl *clone;
587 int ret;
588
589 *acl = NULL;
590 *default_acl = NULL;
591
592 if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
593 return 0;
594
595 p = get_acl(dir, ACL_TYPE_DEFAULT);
596 if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
597 *mode &= ~current_umask();
598 return 0;
599 }
600 if (IS_ERR(p))
601 return PTR_ERR(p);
602
603 ret = -ENOMEM;
604 clone = posix_acl_clone(p, GFP_NOFS);
605 if (!clone)
606 goto err_release;
607
608 ret = posix_acl_create_masq(clone, mode);
609 if (ret < 0)
610 goto err_release_clone;
611
612 if (ret == 0)
613 posix_acl_release(clone);
614 else
615 *acl = clone;
616
617 if (!S_ISDIR(*mode))
618 posix_acl_release(p);
619 else
620 *default_acl = p;
621
622 return 0;
623
624 err_release_clone:
625 posix_acl_release(clone);
626 err_release:
627 posix_acl_release(p);
628 return ret;
629 }
630 EXPORT_SYMBOL_GPL(posix_acl_create);
631
632 /**
633 * posix_acl_update_mode - update mode in set_acl
634 *
635 * Update the file mode when setting an ACL: compute the new file permission
636 * bits based on the ACL. In addition, if the ACL is equivalent to the new
637 * file mode, set *acl to NULL to indicate that no ACL should be set.
638 *
639 * As with chmod, clear the setgit bit if the caller is not in the owning group
640 * or capable of CAP_FSETID (see inode_change_ok).
641 *
642 * Called from set_acl inode operations.
643 */
posix_acl_update_mode(struct inode * inode,umode_t * mode_p,struct posix_acl ** acl)644 int posix_acl_update_mode(struct inode *inode, umode_t *mode_p,
645 struct posix_acl **acl)
646 {
647 umode_t mode = inode->i_mode;
648 int error;
649
650 error = posix_acl_equiv_mode(*acl, &mode);
651 if (error < 0)
652 return error;
653 if (error == 0)
654 *acl = NULL;
655 if (!in_group_p(inode->i_gid) &&
656 !capable_wrt_inode_uidgid(inode, CAP_FSETID))
657 mode &= ~S_ISGID;
658 *mode_p = mode;
659 return 0;
660 }
661 EXPORT_SYMBOL(posix_acl_update_mode);
662
663 /*
664 * Fix up the uids and gids in posix acl extended attributes in place.
665 */
posix_acl_fix_xattr_userns(struct user_namespace * to,struct user_namespace * from,void * value,size_t size)666 static void posix_acl_fix_xattr_userns(
667 struct user_namespace *to, struct user_namespace *from,
668 void *value, size_t size)
669 {
670 struct posix_acl_xattr_header *header = value;
671 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
672 int count;
673 kuid_t uid;
674 kgid_t gid;
675
676 if (!value)
677 return;
678 if (size < sizeof(struct posix_acl_xattr_header))
679 return;
680 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
681 return;
682
683 count = posix_acl_xattr_count(size);
684 if (count < 0)
685 return;
686 if (count == 0)
687 return;
688
689 for (end = entry + count; entry != end; entry++) {
690 switch(le16_to_cpu(entry->e_tag)) {
691 case ACL_USER:
692 uid = make_kuid(from, le32_to_cpu(entry->e_id));
693 entry->e_id = cpu_to_le32(from_kuid(to, uid));
694 break;
695 case ACL_GROUP:
696 gid = make_kgid(from, le32_to_cpu(entry->e_id));
697 entry->e_id = cpu_to_le32(from_kgid(to, gid));
698 break;
699 default:
700 break;
701 }
702 }
703 }
704
posix_acl_fix_xattr_from_user(void * value,size_t size)705 void posix_acl_fix_xattr_from_user(void *value, size_t size)
706 {
707 struct user_namespace *user_ns = current_user_ns();
708 if (user_ns == &init_user_ns)
709 return;
710 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
711 }
712
posix_acl_fix_xattr_to_user(void * value,size_t size)713 void posix_acl_fix_xattr_to_user(void *value, size_t size)
714 {
715 struct user_namespace *user_ns = current_user_ns();
716 if (user_ns == &init_user_ns)
717 return;
718 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
719 }
720
721 /*
722 * Convert from extended attribute to in-memory representation.
723 */
724 struct posix_acl *
posix_acl_from_xattr(struct user_namespace * user_ns,const void * value,size_t size)725 posix_acl_from_xattr(struct user_namespace *user_ns,
726 const void *value, size_t size)
727 {
728 const struct posix_acl_xattr_header *header = value;
729 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
730 int count;
731 struct posix_acl *acl;
732 struct posix_acl_entry *acl_e;
733
734 if (!value)
735 return NULL;
736 if (size < sizeof(struct posix_acl_xattr_header))
737 return ERR_PTR(-EINVAL);
738 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
739 return ERR_PTR(-EOPNOTSUPP);
740
741 count = posix_acl_xattr_count(size);
742 if (count < 0)
743 return ERR_PTR(-EINVAL);
744 if (count == 0)
745 return NULL;
746
747 acl = posix_acl_alloc(count, GFP_NOFS);
748 if (!acl)
749 return ERR_PTR(-ENOMEM);
750 acl_e = acl->a_entries;
751
752 for (end = entry + count; entry != end; acl_e++, entry++) {
753 acl_e->e_tag = le16_to_cpu(entry->e_tag);
754 acl_e->e_perm = le16_to_cpu(entry->e_perm);
755
756 switch(acl_e->e_tag) {
757 case ACL_USER_OBJ:
758 case ACL_GROUP_OBJ:
759 case ACL_MASK:
760 case ACL_OTHER:
761 break;
762
763 case ACL_USER:
764 acl_e->e_uid =
765 make_kuid(user_ns,
766 le32_to_cpu(entry->e_id));
767 if (!uid_valid(acl_e->e_uid))
768 goto fail;
769 break;
770 case ACL_GROUP:
771 acl_e->e_gid =
772 make_kgid(user_ns,
773 le32_to_cpu(entry->e_id));
774 if (!gid_valid(acl_e->e_gid))
775 goto fail;
776 break;
777
778 default:
779 goto fail;
780 }
781 }
782 return acl;
783
784 fail:
785 posix_acl_release(acl);
786 return ERR_PTR(-EINVAL);
787 }
788 EXPORT_SYMBOL (posix_acl_from_xattr);
789
790 /*
791 * Convert from in-memory to extended attribute representation.
792 */
793 int
posix_acl_to_xattr(struct user_namespace * user_ns,const struct posix_acl * acl,void * buffer,size_t size)794 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
795 void *buffer, size_t size)
796 {
797 struct posix_acl_xattr_header *ext_acl = buffer;
798 struct posix_acl_xattr_entry *ext_entry;
799 int real_size, n;
800
801 real_size = posix_acl_xattr_size(acl->a_count);
802 if (!buffer)
803 return real_size;
804 if (real_size > size)
805 return -ERANGE;
806
807 ext_entry = (void *)(ext_acl + 1);
808 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
809
810 for (n=0; n < acl->a_count; n++, ext_entry++) {
811 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
812 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag);
813 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
814 switch(acl_e->e_tag) {
815 case ACL_USER:
816 ext_entry->e_id =
817 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
818 break;
819 case ACL_GROUP:
820 ext_entry->e_id =
821 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
822 break;
823 default:
824 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
825 break;
826 }
827 }
828 return real_size;
829 }
830 EXPORT_SYMBOL (posix_acl_to_xattr);
831
832 static int
posix_acl_xattr_get(const struct xattr_handler * handler,struct dentry * unused,struct inode * inode,const char * name,void * value,size_t size)833 posix_acl_xattr_get(const struct xattr_handler *handler,
834 struct dentry *unused, struct inode *inode,
835 const char *name, void *value, size_t size)
836 {
837 struct posix_acl *acl;
838 int error;
839
840 if (!IS_POSIXACL(inode))
841 return -EOPNOTSUPP;
842 if (S_ISLNK(inode->i_mode))
843 return -EOPNOTSUPP;
844
845 acl = get_acl(inode, handler->flags);
846 if (IS_ERR(acl))
847 return PTR_ERR(acl);
848 if (acl == NULL)
849 return -ENODATA;
850
851 error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
852 posix_acl_release(acl);
853
854 return error;
855 }
856
857 int
set_posix_acl(struct inode * inode,int type,struct posix_acl * acl)858 set_posix_acl(struct inode *inode, int type, struct posix_acl *acl)
859 {
860 if (!IS_POSIXACL(inode))
861 return -EOPNOTSUPP;
862 if (!inode->i_op->set_acl)
863 return -EOPNOTSUPP;
864
865 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
866 return acl ? -EACCES : 0;
867 if (!inode_owner_or_capable(inode))
868 return -EPERM;
869
870 if (acl) {
871 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
872 if (ret)
873 return ret;
874 }
875 return inode->i_op->set_acl(inode, acl, type);
876 }
877 EXPORT_SYMBOL(set_posix_acl);
878
879 static int
posix_acl_xattr_set(const struct xattr_handler * handler,struct dentry * unused,struct inode * inode,const char * name,const void * value,size_t size,int flags)880 posix_acl_xattr_set(const struct xattr_handler *handler,
881 struct dentry *unused, struct inode *inode,
882 const char *name, const void *value,
883 size_t size, int flags)
884 {
885 struct posix_acl *acl = NULL;
886 int ret;
887
888 if (value) {
889 acl = posix_acl_from_xattr(&init_user_ns, value, size);
890 if (IS_ERR(acl))
891 return PTR_ERR(acl);
892 }
893 ret = set_posix_acl(inode, handler->flags, acl);
894 posix_acl_release(acl);
895 return ret;
896 }
897
898 static bool
posix_acl_xattr_list(struct dentry * dentry)899 posix_acl_xattr_list(struct dentry *dentry)
900 {
901 return IS_POSIXACL(d_backing_inode(dentry));
902 }
903
904 const struct xattr_handler posix_acl_access_xattr_handler = {
905 .name = XATTR_NAME_POSIX_ACL_ACCESS,
906 .flags = ACL_TYPE_ACCESS,
907 .list = posix_acl_xattr_list,
908 .get = posix_acl_xattr_get,
909 .set = posix_acl_xattr_set,
910 };
911 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
912
913 const struct xattr_handler posix_acl_default_xattr_handler = {
914 .name = XATTR_NAME_POSIX_ACL_DEFAULT,
915 .flags = ACL_TYPE_DEFAULT,
916 .list = posix_acl_xattr_list,
917 .get = posix_acl_xattr_get,
918 .set = posix_acl_xattr_set,
919 };
920 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
921
simple_set_acl(struct inode * inode,struct posix_acl * acl,int type)922 int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
923 {
924 int error;
925
926 if (type == ACL_TYPE_ACCESS) {
927 error = posix_acl_update_mode(inode,
928 &inode->i_mode, &acl);
929 if (error)
930 return error;
931 }
932
933 inode->i_ctime = current_time(inode);
934 set_cached_acl(inode, type, acl);
935 return 0;
936 }
937
simple_acl_create(struct inode * dir,struct inode * inode)938 int simple_acl_create(struct inode *dir, struct inode *inode)
939 {
940 struct posix_acl *default_acl, *acl;
941 int error;
942
943 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
944 if (error)
945 return error;
946
947 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
948 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
949
950 if (default_acl)
951 posix_acl_release(default_acl);
952 if (acl)
953 posix_acl_release(acl);
954 return 0;
955 }
956
