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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
24static struct posix_acl **acl_by_type(struct inode *inode, int type)
25{
26 switch (type) {
27 case ACL_TYPE_ACCESS:
28 return &inode->i_acl;
29 case ACL_TYPE_DEFAULT:
30 return &inode->i_default_acl;
31 default:
32 BUG();
33 }
34}
35
36struct posix_acl *get_cached_acl(struct inode *inode, int type)
37{
38 struct posix_acl **p = acl_by_type(inode, type);
39 struct posix_acl *acl;
40
41 for (;;) {
42 rcu_read_lock();
43 acl = rcu_dereference(*p);
44 if (!acl || is_uncached_acl(acl) ||
45 atomic_inc_not_zero(&acl->a_refcount))
46 break;
47 rcu_read_unlock();
48 cpu_relax();
49 }
50 rcu_read_unlock();
51 return acl;
52}
53EXPORT_SYMBOL(get_cached_acl);
54
55struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
56{
57 return rcu_dereference(*acl_by_type(inode, type));
58}
59EXPORT_SYMBOL(get_cached_acl_rcu);
60
61void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
62{
63 struct posix_acl **p = acl_by_type(inode, type);
64 struct posix_acl *old;
65
66 old = xchg(p, posix_acl_dup(acl));
67 if (!is_uncached_acl(old))
68 posix_acl_release(old);
69}
70EXPORT_SYMBOL(set_cached_acl);
71
72static void __forget_cached_acl(struct posix_acl **p)
73{
74 struct posix_acl *old;
75
76 old = xchg(p, ACL_NOT_CACHED);
77 if (!is_uncached_acl(old))
78 posix_acl_release(old);
79}
80
81void forget_cached_acl(struct inode *inode, int type)
82{
83 __forget_cached_acl(acl_by_type(inode, type));
84}
85EXPORT_SYMBOL(forget_cached_acl);
86
87void forget_all_cached_acls(struct inode *inode)
88{
89 __forget_cached_acl(&inode->i_acl);
90 __forget_cached_acl(&inode->i_default_acl);
91}
92EXPORT_SYMBOL(forget_all_cached_acls);
93
94struct posix_acl *get_acl(struct inode *inode, int type)
95{
96 void *sentinel;
97 struct posix_acl **p;
98 struct posix_acl *acl;
99
100 /*
101 * The sentinel is used to detect when another operation like
102 * set_cached_acl() or forget_cached_acl() races with get_acl().
103 * It is guaranteed that is_uncached_acl(sentinel) is true.
104 */
105
106 acl = get_cached_acl(inode, type);
107 if (!is_uncached_acl(acl))
108 return acl;
109
110 if (!IS_POSIXACL(inode))
111 return NULL;
112
113 sentinel = uncached_acl_sentinel(current);
114 p = acl_by_type(inode, type);
115
116 /*
117 * If the ACL isn't being read yet, set our sentinel. Otherwise, the
118 * current value of the ACL will not be ACL_NOT_CACHED and so our own
119 * sentinel will not be set; another task will update the cache. We
120 * could wait for that other task to complete its job, but it's easier
121 * to just call ->get_acl to fetch the ACL ourself. (This is going to
122 * be an unlikely race.)
123 */
124 if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED)
125 /* fall through */ ;
126
127 /*
128 * Normally, the ACL returned by ->get_acl will be cached.
129 * A filesystem can prevent that by calling
130 * forget_cached_acl(inode, type) in ->get_acl.
131 *
132 * If the filesystem doesn't have a get_acl() function at all, we'll
133 * just create the negative cache entry.
134 */
135 if (!inode->i_op->get_acl) {
136 set_cached_acl(inode, type, NULL);
137 return NULL;
138 }
139 acl = inode->i_op->get_acl(inode, type);
140
141 if (IS_ERR(acl)) {
142 /*
143 * Remove our sentinel so that we don't block future attempts
144 * to cache the ACL.
145 */
146 cmpxchg(p, sentinel, ACL_NOT_CACHED);
147 return acl;
148 }
149
150 /*
151 * Cache the result, but only if our sentinel is still in place.
152 */
153 posix_acl_dup(acl);
154 if (unlikely(cmpxchg(p, sentinel, acl) != sentinel))
155 posix_acl_release(acl);
156 return acl;
157}
158EXPORT_SYMBOL(get_acl);
159
160/*
161 * Init a fresh posix_acl
162 */
163void
164posix_acl_init(struct posix_acl *acl, int count)
165{
166 atomic_set(&acl->a_refcount, 1);
167 acl->a_count = count;
168}
169EXPORT_SYMBOL(posix_acl_init);
170
171/*
172 * Allocate a new ACL with the specified number of entries.
173 */
174struct posix_acl *
175posix_acl_alloc(int count, gfp_t flags)
176{
177 const size_t size = sizeof(struct posix_acl) +
178 count * sizeof(struct posix_acl_entry);
179 struct posix_acl *acl = kmalloc(size, flags);
180 if (acl)
181 posix_acl_init(acl, count);
182 return acl;
183}
184EXPORT_SYMBOL(posix_acl_alloc);
185
186/*
187 * Clone an ACL.
188 */
189static struct posix_acl *
190posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
191{
192 struct posix_acl *clone = NULL;
193
194 if (acl) {
195 int size = sizeof(struct posix_acl) + acl->a_count *
196 sizeof(struct posix_acl_entry);
197 clone = kmemdup(acl, size, flags);
198 if (clone)
199 atomic_set(&clone->a_refcount, 1);
200 }
201 return clone;
202}
203
204/*
205 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
206 */
207int
208posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl)
209{
210 const struct posix_acl_entry *pa, *pe;
211 int state = ACL_USER_OBJ;
212 int needs_mask = 0;
213
214 FOREACH_ACL_ENTRY(pa, acl, pe) {
215 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
216 return -EINVAL;
217 switch (pa->e_tag) {
218 case ACL_USER_OBJ:
219 if (state == ACL_USER_OBJ) {
220 state = ACL_USER;
221 break;
222 }
223 return -EINVAL;
224
225 case ACL_USER:
226 if (state != ACL_USER)
227 return -EINVAL;
228 if (!kuid_has_mapping(user_ns, pa->e_uid))
229 return -EINVAL;
230 needs_mask = 1;
231 break;
232
233 case ACL_GROUP_OBJ:
234 if (state == ACL_USER) {
235 state = ACL_GROUP;
236 break;
237 }
238 return -EINVAL;
239
240 case ACL_GROUP:
241 if (state != ACL_GROUP)
242 return -EINVAL;
243 if (!kgid_has_mapping(user_ns, pa->e_gid))
244 return -EINVAL;
245 needs_mask = 1;
246 break;
247
248 case ACL_MASK:
249 if (state != ACL_GROUP)
250 return -EINVAL;
251 state = ACL_OTHER;
252 break;
253
254 case ACL_OTHER:
255 if (state == ACL_OTHER ||
256 (state == ACL_GROUP && !needs_mask)) {
257 state = 0;
258 break;
259 }
260 return -EINVAL;
261
262 default:
263 return -EINVAL;
264 }
265 }
266 if (state == 0)
267 return 0;
268 return -EINVAL;
269}
270EXPORT_SYMBOL(posix_acl_valid);
271
272/*
273 * Returns 0 if the acl can be exactly represented in the traditional
274 * file mode permission bits, or else 1. Returns -E... on error.
275 */
276int
277posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
278{
279 const struct posix_acl_entry *pa, *pe;
280 umode_t mode = 0;
281 int not_equiv = 0;
282
283 /*
284 * A null ACL can always be presented as mode bits.
285 */
286 if (!acl)
287 return 0;
288
289 FOREACH_ACL_ENTRY(pa, acl, pe) {
290 switch (pa->e_tag) {
291 case ACL_USER_OBJ:
292 mode |= (pa->e_perm & S_IRWXO) << 6;
293 break;
294 case ACL_GROUP_OBJ:
295 mode |= (pa->e_perm & S_IRWXO) << 3;
296 break;
297 case ACL_OTHER:
298 mode |= pa->e_perm & S_IRWXO;
299 break;
300 case ACL_MASK:
301 mode = (mode & ~S_IRWXG) |
302 ((pa->e_perm & S_IRWXO) << 3);
303 not_equiv = 1;
304 break;
305 case ACL_USER:
306 case ACL_GROUP:
307 not_equiv = 1;
308 break;
309 default:
310 return -EINVAL;
311 }
312 }
313 if (mode_p)
314 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
315 return not_equiv;
316}
317EXPORT_SYMBOL(posix_acl_equiv_mode);
318
319/*
320 * Create an ACL representing the file mode permission bits of an inode.
321 */
322struct posix_acl *
323posix_acl_from_mode(umode_t mode, gfp_t flags)
324{
325 struct posix_acl *acl = posix_acl_alloc(3, flags);
326 if (!acl)
327 return ERR_PTR(-ENOMEM);
328
329 acl->a_entries[0].e_tag = ACL_USER_OBJ;
330 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
331
332 acl->a_entries[1].e_tag = ACL_GROUP_OBJ;
333 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
334
335 acl->a_entries[2].e_tag = ACL_OTHER;
336 acl->a_entries[2].e_perm = (mode & S_IRWXO);
337 return acl;
338}
339EXPORT_SYMBOL(posix_acl_from_mode);
340
341/*
342 * Return 0 if current is granted want access to the inode
343 * by the acl. Returns -E... otherwise.
344 */
345int
346posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
347{
348 const struct posix_acl_entry *pa, *pe, *mask_obj;
349 int found = 0;
350
351 want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
352
353 FOREACH_ACL_ENTRY(pa, acl, pe) {
354 switch(pa->e_tag) {
355 case ACL_USER_OBJ:
356 /* (May have been checked already) */
357 if (uid_eq(inode->i_uid, current_fsuid()))
358 goto check_perm;
359 break;
360 case ACL_USER:
361 if (uid_eq(pa->e_uid, current_fsuid()))
362 goto mask;
363 break;
364 case ACL_GROUP_OBJ:
365 if (in_group_p(inode->i_gid)) {
366 found = 1;
367 if ((pa->e_perm & want) == want)
368 goto mask;
369 }
370 break;
371 case ACL_GROUP:
372 if (in_group_p(pa->e_gid)) {
373 found = 1;
374 if ((pa->e_perm & want) == want)
375 goto mask;
376 }
377 break;
378 case ACL_MASK:
379 break;
380 case ACL_OTHER:
381 if (found)
382 return -EACCES;
383 else
384 goto check_perm;
385 default:
386 return -EIO;
387 }
388 }
389 return -EIO;
390
391mask:
392 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
393 if (mask_obj->e_tag == ACL_MASK) {
394 if ((pa->e_perm & mask_obj->e_perm & want) == want)
395 return 0;
396 return -EACCES;
397 }
398 }
399
400check_perm:
401 if ((pa->e_perm & want) == want)
402 return 0;
403 return -EACCES;
404}
405
406/*
407 * Modify acl when creating a new inode. The caller must ensure the acl is
408 * only referenced once.
409 *
410 * mode_p initially must contain the mode parameter to the open() / creat()
411 * system calls. All permissions that are not granted by the acl are removed.
412 * The permissions in the acl are changed to reflect the mode_p parameter.
413 */
414static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
415{
416 struct posix_acl_entry *pa, *pe;
417 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
418 umode_t mode = *mode_p;
419 int not_equiv = 0;
420
421 /* assert(atomic_read(acl->a_refcount) == 1); */
422
423 FOREACH_ACL_ENTRY(pa, acl, pe) {
424 switch(pa->e_tag) {
425 case ACL_USER_OBJ:
426 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
427 mode &= (pa->e_perm << 6) | ~S_IRWXU;
428 break;
429
430 case ACL_USER:
431 case ACL_GROUP:
432 not_equiv = 1;
433 break;
434
435 case ACL_GROUP_OBJ:
436 group_obj = pa;
437 break;
438
439 case ACL_OTHER:
440 pa->e_perm &= mode | ~S_IRWXO;
441 mode &= pa->e_perm | ~S_IRWXO;
442 break;
443
444 case ACL_MASK:
445 mask_obj = pa;
446 not_equiv = 1;
447 break;
448
449 default:
450 return -EIO;
451 }
452 }
453
454 if (mask_obj) {
455 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
456 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
457 } else {
458 if (!group_obj)
459 return -EIO;
460 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
461 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
462 }
463
464 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
465 return not_equiv;
466}
467
468/*
469 * Modify the ACL for the chmod syscall.
470 */
471static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
472{
473 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
474 struct posix_acl_entry *pa, *pe;
475
476 /* assert(atomic_read(acl->a_refcount) == 1); */
477
478 FOREACH_ACL_ENTRY(pa, acl, pe) {
479 switch(pa->e_tag) {
480 case ACL_USER_OBJ:
481 pa->e_perm = (mode & S_IRWXU) >> 6;
482 break;
483
484 case ACL_USER:
485 case ACL_GROUP:
486 break;
487
488 case ACL_GROUP_OBJ:
489 group_obj = pa;
490 break;
491
492 case ACL_MASK:
493 mask_obj = pa;
494 break;
495
496 case ACL_OTHER:
497 pa->e_perm = (mode & S_IRWXO);
498 break;
499
500 default:
501 return -EIO;
502 }
503 }
504
505 if (mask_obj) {
506 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
507 } else {
508 if (!group_obj)
509 return -EIO;
510 group_obj->e_perm = (mode & S_IRWXG) >> 3;
511 }
512
513 return 0;
514}
515
516int
517__posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
518{
519 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
520 int err = -ENOMEM;
521 if (clone) {
522 err = posix_acl_create_masq(clone, mode_p);
523 if (err < 0) {
524 posix_acl_release(clone);
525 clone = NULL;
526 }
527 }
528 posix_acl_release(*acl);
529 *acl = clone;
530 return err;
531}
532EXPORT_SYMBOL(__posix_acl_create);
533
534int
535__posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
536{
537 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
538 int err = -ENOMEM;
539 if (clone) {
540 err = __posix_acl_chmod_masq(clone, mode);
541 if (err) {
542 posix_acl_release(clone);
543 clone = NULL;
544 }
545 }
546 posix_acl_release(*acl);
547 *acl = clone;
548 return err;
549}
550EXPORT_SYMBOL(__posix_acl_chmod);
551
552int
553posix_acl_chmod(struct inode *inode, umode_t mode)
554{
555 struct posix_acl *acl;
556 int ret = 0;
557
558 if (!IS_POSIXACL(inode))
559 return 0;
560 if (!inode->i_op->set_acl)
561 return -EOPNOTSUPP;
562
563 acl = get_acl(inode, ACL_TYPE_ACCESS);
564 if (IS_ERR_OR_NULL(acl)) {
565 if (acl == ERR_PTR(-EOPNOTSUPP))
566 return 0;
567 return PTR_ERR(acl);
568 }
569
570 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
571 if (ret)
572 return ret;
573 ret = inode->i_op->set_acl(inode, acl, ACL_TYPE_ACCESS);
574 posix_acl_release(acl);
575 return ret;
576}
577EXPORT_SYMBOL(posix_acl_chmod);
578
579int
580posix_acl_create(struct inode *dir, umode_t *mode,
581 struct posix_acl **default_acl, struct posix_acl **acl)
582{
583 struct posix_acl *p;
584 struct posix_acl *clone;
585 int ret;
586
587 *acl = NULL;
588 *default_acl = NULL;
589
590 if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
591 return 0;
592
593 p = get_acl(dir, ACL_TYPE_DEFAULT);
594 if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
595 *mode &= ~current_umask();
596 return 0;
597 }
598 if (IS_ERR(p))
599 return PTR_ERR(p);
600
601 ret = -ENOMEM;
602 clone = posix_acl_clone(p, GFP_NOFS);
603 if (!clone)
604 goto err_release;
605
606 ret = posix_acl_create_masq(clone, mode);
607 if (ret < 0)
608 goto err_release_clone;
609
610 if (ret == 0)
611 posix_acl_release(clone);
612 else
613 *acl = clone;
614
615 if (!S_ISDIR(*mode))
616 posix_acl_release(p);
617 else
618 *default_acl = p;
619
620 return 0;
621
622err_release_clone:
623 posix_acl_release(clone);
624err_release:
625 posix_acl_release(p);
626 return ret;
627}
628EXPORT_SYMBOL_GPL(posix_acl_create);
629
630/**
631 * posix_acl_update_mode - update mode in set_acl
632 *
633 * Update the file mode when setting an ACL: compute the new file permission
634 * bits based on the ACL. In addition, if the ACL is equivalent to the new
635 * file mode, set *acl to NULL to indicate that no ACL should be set.
636 *
637 * As with chmod, clear the setgit bit if the caller is not in the owning group
638 * or capable of CAP_FSETID (see inode_change_ok).
639 *
640 * Called from set_acl inode operations.
641 */
642int posix_acl_update_mode(struct inode *inode, umode_t *mode_p,
643 struct posix_acl **acl)
644{
645 umode_t mode = inode->i_mode;
646 int error;
647
648 error = posix_acl_equiv_mode(*acl, &mode);
649 if (error < 0)
650 return error;
651 if (error == 0)
652 *acl = NULL;
653 if (!in_group_p(inode->i_gid) &&
654 !capable_wrt_inode_uidgid(inode, CAP_FSETID))
655 mode &= ~S_ISGID;
656 *mode_p = mode;
657 return 0;
658}
659EXPORT_SYMBOL(posix_acl_update_mode);
660
661/*
662 * Fix up the uids and gids in posix acl extended attributes in place.
663 */
664static void posix_acl_fix_xattr_userns(
665 struct user_namespace *to, struct user_namespace *from,
666 void *value, size_t size)
667{
668 struct posix_acl_xattr_header *header = value;
669 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
670 int count;
671 kuid_t uid;
672 kgid_t gid;
673
674 if (!value)
675 return;
676 if (size < sizeof(struct posix_acl_xattr_header))
677 return;
678 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
679 return;
680
681 count = posix_acl_xattr_count(size);
682 if (count < 0)
683 return;
684 if (count == 0)
685 return;
686
687 for (end = entry + count; entry != end; entry++) {
688 switch(le16_to_cpu(entry->e_tag)) {
689 case ACL_USER:
690 uid = make_kuid(from, le32_to_cpu(entry->e_id));
691 entry->e_id = cpu_to_le32(from_kuid(to, uid));
692 break;
693 case ACL_GROUP:
694 gid = make_kgid(from, le32_to_cpu(entry->e_id));
695 entry->e_id = cpu_to_le32(from_kgid(to, gid));
696 break;
697 default:
698 break;
699 }
700 }
701}
702
703void posix_acl_fix_xattr_from_user(void *value, size_t size)
704{
705 struct user_namespace *user_ns = current_user_ns();
706 if (user_ns == &init_user_ns)
707 return;
708 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
709}
710
711void posix_acl_fix_xattr_to_user(void *value, size_t size)
712{
713 struct user_namespace *user_ns = current_user_ns();
714 if (user_ns == &init_user_ns)
715 return;
716 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
717}
718
719/*
720 * Convert from extended attribute to in-memory representation.
721 */
722struct posix_acl *
723posix_acl_from_xattr(struct user_namespace *user_ns,
724 const void *value, size_t size)
725{
726 const struct posix_acl_xattr_header *header = value;
727 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
728 int count;
729 struct posix_acl *acl;
730 struct posix_acl_entry *acl_e;
731
732 if (!value)
733 return NULL;
734 if (size < sizeof(struct posix_acl_xattr_header))
735 return ERR_PTR(-EINVAL);
736 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
737 return ERR_PTR(-EOPNOTSUPP);
738
739 count = posix_acl_xattr_count(size);
740 if (count < 0)
741 return ERR_PTR(-EINVAL);
742 if (count == 0)
743 return NULL;
744
745 acl = posix_acl_alloc(count, GFP_NOFS);
746 if (!acl)
747 return ERR_PTR(-ENOMEM);
748 acl_e = acl->a_entries;
749
750 for (end = entry + count; entry != end; acl_e++, entry++) {
751 acl_e->e_tag = le16_to_cpu(entry->e_tag);
752 acl_e->e_perm = le16_to_cpu(entry->e_perm);
753
754 switch(acl_e->e_tag) {
755 case ACL_USER_OBJ:
756 case ACL_GROUP_OBJ:
757 case ACL_MASK:
758 case ACL_OTHER:
759 break;
760
761 case ACL_USER:
762 acl_e->e_uid =
763 make_kuid(user_ns,
764 le32_to_cpu(entry->e_id));
765 if (!uid_valid(acl_e->e_uid))
766 goto fail;
767 break;
768 case ACL_GROUP:
769 acl_e->e_gid =
770 make_kgid(user_ns,
771 le32_to_cpu(entry->e_id));
772 if (!gid_valid(acl_e->e_gid))
773 goto fail;
774 break;
775
776 default:
777 goto fail;
778 }
779 }
780 return acl;
781
782fail:
783 posix_acl_release(acl);
784 return ERR_PTR(-EINVAL);
785}
786EXPORT_SYMBOL (posix_acl_from_xattr);
787
788/*
789 * Convert from in-memory to extended attribute representation.
790 */
791int
792posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
793 void *buffer, size_t size)
794{
795 struct posix_acl_xattr_header *ext_acl = buffer;
796 struct posix_acl_xattr_entry *ext_entry;
797 int real_size, n;
798
799 real_size = posix_acl_xattr_size(acl->a_count);
800 if (!buffer)
801 return real_size;
802 if (real_size > size)
803 return -ERANGE;
804
805 ext_entry = (void *)(ext_acl + 1);
806 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
807
808 for (n=0; n < acl->a_count; n++, ext_entry++) {
809 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
810 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag);
811 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
812 switch(acl_e->e_tag) {
813 case ACL_USER:
814 ext_entry->e_id =
815 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
816 break;
817 case ACL_GROUP:
818 ext_entry->e_id =
819 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
820 break;
821 default:
822 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
823 break;
824 }
825 }
826 return real_size;
827}
828EXPORT_SYMBOL (posix_acl_to_xattr);
829
830static int
831posix_acl_xattr_get(const struct xattr_handler *handler,
832 struct dentry *unused, struct inode *inode,
833 const char *name, void *value, size_t size)
834{
835 struct posix_acl *acl;
836 int error;
837
838 if (!IS_POSIXACL(inode))
839 return -EOPNOTSUPP;
840 if (S_ISLNK(inode->i_mode))
841 return -EOPNOTSUPP;
842
843 acl = get_acl(inode, handler->flags);
844 if (IS_ERR(acl))
845 return PTR_ERR(acl);
846 if (acl == NULL)
847 return -ENODATA;
848
849 error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
850 posix_acl_release(acl);
851
852 return error;
853}
854
855int
856set_posix_acl(struct inode *inode, int type, struct posix_acl *acl)
857{
858 if (!IS_POSIXACL(inode))
859 return -EOPNOTSUPP;
860 if (!inode->i_op->set_acl)
861 return -EOPNOTSUPP;
862
863 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
864 return acl ? -EACCES : 0;
865 if (!inode_owner_or_capable(inode))
866 return -EPERM;
867
868 if (acl) {
869 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
870 if (ret)
871 return ret;
872 }
873 return inode->i_op->set_acl(inode, acl, type);
874}
875EXPORT_SYMBOL(set_posix_acl);
876
877static int
878posix_acl_xattr_set(const struct xattr_handler *handler,
879 struct dentry *unused, struct inode *inode,
880 const char *name, const void *value,
881 size_t size, int flags)
882{
883 struct posix_acl *acl = NULL;
884 int ret;
885
886 if (value) {
887 acl = posix_acl_from_xattr(&init_user_ns, value, size);
888 if (IS_ERR(acl))
889 return PTR_ERR(acl);
890 }
891 ret = set_posix_acl(inode, handler->flags, acl);
892 posix_acl_release(acl);
893 return ret;
894}
895
896static bool
897posix_acl_xattr_list(struct dentry *dentry)
898{
899 return IS_POSIXACL(d_backing_inode(dentry));
900}
901
902const struct xattr_handler posix_acl_access_xattr_handler = {
903 .name = XATTR_NAME_POSIX_ACL_ACCESS,
904 .flags = ACL_TYPE_ACCESS,
905 .list = posix_acl_xattr_list,
906 .get = posix_acl_xattr_get,
907 .set = posix_acl_xattr_set,
908};
909EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
910
911const struct xattr_handler posix_acl_default_xattr_handler = {
912 .name = XATTR_NAME_POSIX_ACL_DEFAULT,
913 .flags = ACL_TYPE_DEFAULT,
914 .list = posix_acl_xattr_list,
915 .get = posix_acl_xattr_get,
916 .set = posix_acl_xattr_set,
917};
918EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
919
920int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
921{
922 int error;
923
924 if (type == ACL_TYPE_ACCESS) {
925 error = posix_acl_update_mode(inode,
926 &inode->i_mode, &acl);
927 if (error)
928 return error;
929 }
930
931 inode->i_ctime = current_time(inode);
932 set_cached_acl(inode, type, acl);
933 return 0;
934}
935
936int simple_acl_create(struct inode *dir, struct inode *inode)
937{
938 struct posix_acl *default_acl, *acl;
939 int error;
940
941 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
942 if (error)
943 return error;
944
945 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
946 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
947
948 if (default_acl)
949 posix_acl_release(default_acl);
950 if (acl)
951 posix_acl_release(acl);
952 return 0;
953}
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#include <linux/namei.h>
26#include <linux/mnt_idmapping.h>
27#include <linux/iversion.h>
28#include <linux/security.h>
29#include <linux/evm.h>
30#include <linux/fsnotify.h>
31#include <linux/filelock.h>
32
33#include "internal.h"
34
35static struct posix_acl **acl_by_type(struct inode *inode, int type)
36{
37 switch (type) {
38 case ACL_TYPE_ACCESS:
39 return &inode->i_acl;
40 case ACL_TYPE_DEFAULT:
41 return &inode->i_default_acl;
42 default:
43 BUG();
44 }
45}
46
47struct posix_acl *get_cached_acl(struct inode *inode, int type)
48{
49 struct posix_acl **p = acl_by_type(inode, type);
50 struct posix_acl *acl;
51
52 for (;;) {
53 rcu_read_lock();
54 acl = rcu_dereference(*p);
55 if (!acl || is_uncached_acl(acl) ||
56 refcount_inc_not_zero(&acl->a_refcount))
57 break;
58 rcu_read_unlock();
59 cpu_relax();
60 }
61 rcu_read_unlock();
62 return acl;
63}
64EXPORT_SYMBOL(get_cached_acl);
65
66struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
67{
68 struct posix_acl *acl = rcu_dereference(*acl_by_type(inode, type));
69
70 if (acl == ACL_DONT_CACHE) {
71 struct posix_acl *ret;
72
73 ret = inode->i_op->get_inode_acl(inode, type, LOOKUP_RCU);
74 if (!IS_ERR(ret))
75 acl = ret;
76 }
77
78 return acl;
79}
80EXPORT_SYMBOL(get_cached_acl_rcu);
81
82void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
83{
84 struct posix_acl **p = acl_by_type(inode, type);
85 struct posix_acl *old;
86
87 old = xchg(p, posix_acl_dup(acl));
88 if (!is_uncached_acl(old))
89 posix_acl_release(old);
90}
91EXPORT_SYMBOL(set_cached_acl);
92
93static void __forget_cached_acl(struct posix_acl **p)
94{
95 struct posix_acl *old;
96
97 old = xchg(p, ACL_NOT_CACHED);
98 if (!is_uncached_acl(old))
99 posix_acl_release(old);
100}
101
102void forget_cached_acl(struct inode *inode, int type)
103{
104 __forget_cached_acl(acl_by_type(inode, type));
105}
106EXPORT_SYMBOL(forget_cached_acl);
107
108void forget_all_cached_acls(struct inode *inode)
109{
110 __forget_cached_acl(&inode->i_acl);
111 __forget_cached_acl(&inode->i_default_acl);
112}
113EXPORT_SYMBOL(forget_all_cached_acls);
114
115static struct posix_acl *__get_acl(struct mnt_idmap *idmap,
116 struct dentry *dentry, struct inode *inode,
117 int type)
118{
119 struct posix_acl *sentinel;
120 struct posix_acl **p;
121 struct posix_acl *acl;
122
123 /*
124 * The sentinel is used to detect when another operation like
125 * set_cached_acl() or forget_cached_acl() races with get_inode_acl().
126 * It is guaranteed that is_uncached_acl(sentinel) is true.
127 */
128
129 acl = get_cached_acl(inode, type);
130 if (!is_uncached_acl(acl))
131 return acl;
132
133 if (!IS_POSIXACL(inode))
134 return NULL;
135
136 sentinel = uncached_acl_sentinel(current);
137 p = acl_by_type(inode, type);
138
139 /*
140 * If the ACL isn't being read yet, set our sentinel. Otherwise, the
141 * current value of the ACL will not be ACL_NOT_CACHED and so our own
142 * sentinel will not be set; another task will update the cache. We
143 * could wait for that other task to complete its job, but it's easier
144 * to just call ->get_inode_acl to fetch the ACL ourself. (This is
145 * going to be an unlikely race.)
146 */
147 cmpxchg(p, ACL_NOT_CACHED, sentinel);
148
149 /*
150 * Normally, the ACL returned by ->get{_inode}_acl will be cached.
151 * A filesystem can prevent that by calling
152 * forget_cached_acl(inode, type) in ->get{_inode}_acl.
153 *
154 * If the filesystem doesn't have a get{_inode}_ acl() function at all,
155 * we'll just create the negative cache entry.
156 */
157 if (dentry && inode->i_op->get_acl) {
158 acl = inode->i_op->get_acl(idmap, dentry, type);
159 } else if (inode->i_op->get_inode_acl) {
160 acl = inode->i_op->get_inode_acl(inode, type, false);
161 } else {
162 set_cached_acl(inode, type, NULL);
163 return NULL;
164 }
165 if (IS_ERR(acl)) {
166 /*
167 * Remove our sentinel so that we don't block future attempts
168 * to cache the ACL.
169 */
170 cmpxchg(p, sentinel, ACL_NOT_CACHED);
171 return acl;
172 }
173
174 /*
175 * Cache the result, but only if our sentinel is still in place.
176 */
177 posix_acl_dup(acl);
178 if (unlikely(!try_cmpxchg(p, &sentinel, acl)))
179 posix_acl_release(acl);
180 return acl;
181}
182
183struct posix_acl *get_inode_acl(struct inode *inode, int type)
184{
185 return __get_acl(&nop_mnt_idmap, NULL, inode, type);
186}
187EXPORT_SYMBOL(get_inode_acl);
188
189/*
190 * Init a fresh posix_acl
191 */
192void
193posix_acl_init(struct posix_acl *acl, int count)
194{
195 refcount_set(&acl->a_refcount, 1);
196 acl->a_count = count;
197}
198EXPORT_SYMBOL(posix_acl_init);
199
200/*
201 * Allocate a new ACL with the specified number of entries.
202 */
203struct posix_acl *
204posix_acl_alloc(int count, gfp_t flags)
205{
206 const size_t size = sizeof(struct posix_acl) +
207 count * sizeof(struct posix_acl_entry);
208 struct posix_acl *acl = kmalloc(size, flags);
209 if (acl)
210 posix_acl_init(acl, count);
211 return acl;
212}
213EXPORT_SYMBOL(posix_acl_alloc);
214
215/*
216 * Clone an ACL.
217 */
218struct posix_acl *
219posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
220{
221 struct posix_acl *clone = NULL;
222
223 if (acl) {
224 int size = sizeof(struct posix_acl) + acl->a_count *
225 sizeof(struct posix_acl_entry);
226 clone = kmemdup(acl, size, flags);
227 if (clone)
228 refcount_set(&clone->a_refcount, 1);
229 }
230 return clone;
231}
232EXPORT_SYMBOL_GPL(posix_acl_clone);
233
234/*
235 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
236 */
237int
238posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl)
239{
240 const struct posix_acl_entry *pa, *pe;
241 int state = ACL_USER_OBJ;
242 int needs_mask = 0;
243
244 FOREACH_ACL_ENTRY(pa, acl, pe) {
245 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
246 return -EINVAL;
247 switch (pa->e_tag) {
248 case ACL_USER_OBJ:
249 if (state == ACL_USER_OBJ) {
250 state = ACL_USER;
251 break;
252 }
253 return -EINVAL;
254
255 case ACL_USER:
256 if (state != ACL_USER)
257 return -EINVAL;
258 if (!kuid_has_mapping(user_ns, pa->e_uid))
259 return -EINVAL;
260 needs_mask = 1;
261 break;
262
263 case ACL_GROUP_OBJ:
264 if (state == ACL_USER) {
265 state = ACL_GROUP;
266 break;
267 }
268 return -EINVAL;
269
270 case ACL_GROUP:
271 if (state != ACL_GROUP)
272 return -EINVAL;
273 if (!kgid_has_mapping(user_ns, pa->e_gid))
274 return -EINVAL;
275 needs_mask = 1;
276 break;
277
278 case ACL_MASK:
279 if (state != ACL_GROUP)
280 return -EINVAL;
281 state = ACL_OTHER;
282 break;
283
284 case ACL_OTHER:
285 if (state == ACL_OTHER ||
286 (state == ACL_GROUP && !needs_mask)) {
287 state = 0;
288 break;
289 }
290 return -EINVAL;
291
292 default:
293 return -EINVAL;
294 }
295 }
296 if (state == 0)
297 return 0;
298 return -EINVAL;
299}
300EXPORT_SYMBOL(posix_acl_valid);
301
302/*
303 * Returns 0 if the acl can be exactly represented in the traditional
304 * file mode permission bits, or else 1. Returns -E... on error.
305 */
306int
307posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
308{
309 const struct posix_acl_entry *pa, *pe;
310 umode_t mode = 0;
311 int not_equiv = 0;
312
313 /*
314 * A null ACL can always be presented as mode bits.
315 */
316 if (!acl)
317 return 0;
318
319 FOREACH_ACL_ENTRY(pa, acl, pe) {
320 switch (pa->e_tag) {
321 case ACL_USER_OBJ:
322 mode |= (pa->e_perm & S_IRWXO) << 6;
323 break;
324 case ACL_GROUP_OBJ:
325 mode |= (pa->e_perm & S_IRWXO) << 3;
326 break;
327 case ACL_OTHER:
328 mode |= pa->e_perm & S_IRWXO;
329 break;
330 case ACL_MASK:
331 mode = (mode & ~S_IRWXG) |
332 ((pa->e_perm & S_IRWXO) << 3);
333 not_equiv = 1;
334 break;
335 case ACL_USER:
336 case ACL_GROUP:
337 not_equiv = 1;
338 break;
339 default:
340 return -EINVAL;
341 }
342 }
343 if (mode_p)
344 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
345 return not_equiv;
346}
347EXPORT_SYMBOL(posix_acl_equiv_mode);
348
349/*
350 * Create an ACL representing the file mode permission bits of an inode.
351 */
352struct posix_acl *
353posix_acl_from_mode(umode_t mode, gfp_t flags)
354{
355 struct posix_acl *acl = posix_acl_alloc(3, flags);
356 if (!acl)
357 return ERR_PTR(-ENOMEM);
358
359 acl->a_entries[0].e_tag = ACL_USER_OBJ;
360 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
361
362 acl->a_entries[1].e_tag = ACL_GROUP_OBJ;
363 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
364
365 acl->a_entries[2].e_tag = ACL_OTHER;
366 acl->a_entries[2].e_perm = (mode & S_IRWXO);
367 return acl;
368}
369EXPORT_SYMBOL(posix_acl_from_mode);
370
371/*
372 * Return 0 if current is granted want access to the inode
373 * by the acl. Returns -E... otherwise.
374 */
375int
376posix_acl_permission(struct mnt_idmap *idmap, struct inode *inode,
377 const struct posix_acl *acl, int want)
378{
379 const struct posix_acl_entry *pa, *pe, *mask_obj;
380 struct user_namespace *fs_userns = i_user_ns(inode);
381 int found = 0;
382 vfsuid_t vfsuid;
383 vfsgid_t vfsgid;
384
385 want &= MAY_READ | MAY_WRITE | MAY_EXEC;
386
387 FOREACH_ACL_ENTRY(pa, acl, pe) {
388 switch(pa->e_tag) {
389 case ACL_USER_OBJ:
390 /* (May have been checked already) */
391 vfsuid = i_uid_into_vfsuid(idmap, inode);
392 if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
393 goto check_perm;
394 break;
395 case ACL_USER:
396 vfsuid = make_vfsuid(idmap, fs_userns,
397 pa->e_uid);
398 if (vfsuid_eq_kuid(vfsuid, current_fsuid()))
399 goto mask;
400 break;
401 case ACL_GROUP_OBJ:
402 vfsgid = i_gid_into_vfsgid(idmap, inode);
403 if (vfsgid_in_group_p(vfsgid)) {
404 found = 1;
405 if ((pa->e_perm & want) == want)
406 goto mask;
407 }
408 break;
409 case ACL_GROUP:
410 vfsgid = make_vfsgid(idmap, fs_userns,
411 pa->e_gid);
412 if (vfsgid_in_group_p(vfsgid)) {
413 found = 1;
414 if ((pa->e_perm & want) == want)
415 goto mask;
416 }
417 break;
418 case ACL_MASK:
419 break;
420 case ACL_OTHER:
421 if (found)
422 return -EACCES;
423 else
424 goto check_perm;
425 default:
426 return -EIO;
427 }
428 }
429 return -EIO;
430
431mask:
432 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
433 if (mask_obj->e_tag == ACL_MASK) {
434 if ((pa->e_perm & mask_obj->e_perm & want) == want)
435 return 0;
436 return -EACCES;
437 }
438 }
439
440check_perm:
441 if ((pa->e_perm & want) == want)
442 return 0;
443 return -EACCES;
444}
445
446/*
447 * Modify acl when creating a new inode. The caller must ensure the acl is
448 * only referenced once.
449 *
450 * mode_p initially must contain the mode parameter to the open() / creat()
451 * system calls. All permissions that are not granted by the acl are removed.
452 * The permissions in the acl are changed to reflect the mode_p parameter.
453 */
454static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
455{
456 struct posix_acl_entry *pa, *pe;
457 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
458 umode_t mode = *mode_p;
459 int not_equiv = 0;
460
461 /* assert(atomic_read(acl->a_refcount) == 1); */
462
463 FOREACH_ACL_ENTRY(pa, acl, pe) {
464 switch(pa->e_tag) {
465 case ACL_USER_OBJ:
466 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
467 mode &= (pa->e_perm << 6) | ~S_IRWXU;
468 break;
469
470 case ACL_USER:
471 case ACL_GROUP:
472 not_equiv = 1;
473 break;
474
475 case ACL_GROUP_OBJ:
476 group_obj = pa;
477 break;
478
479 case ACL_OTHER:
480 pa->e_perm &= mode | ~S_IRWXO;
481 mode &= pa->e_perm | ~S_IRWXO;
482 break;
483
484 case ACL_MASK:
485 mask_obj = pa;
486 not_equiv = 1;
487 break;
488
489 default:
490 return -EIO;
491 }
492 }
493
494 if (mask_obj) {
495 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
496 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
497 } else {
498 if (!group_obj)
499 return -EIO;
500 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
501 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
502 }
503
504 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
505 return not_equiv;
506}
507
508/*
509 * Modify the ACL for the chmod syscall.
510 */
511static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
512{
513 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
514 struct posix_acl_entry *pa, *pe;
515
516 /* assert(atomic_read(acl->a_refcount) == 1); */
517
518 FOREACH_ACL_ENTRY(pa, acl, pe) {
519 switch(pa->e_tag) {
520 case ACL_USER_OBJ:
521 pa->e_perm = (mode & S_IRWXU) >> 6;
522 break;
523
524 case ACL_USER:
525 case ACL_GROUP:
526 break;
527
528 case ACL_GROUP_OBJ:
529 group_obj = pa;
530 break;
531
532 case ACL_MASK:
533 mask_obj = pa;
534 break;
535
536 case ACL_OTHER:
537 pa->e_perm = (mode & S_IRWXO);
538 break;
539
540 default:
541 return -EIO;
542 }
543 }
544
545 if (mask_obj) {
546 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
547 } else {
548 if (!group_obj)
549 return -EIO;
550 group_obj->e_perm = (mode & S_IRWXG) >> 3;
551 }
552
553 return 0;
554}
555
556int
557__posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
558{
559 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
560 int err = -ENOMEM;
561 if (clone) {
562 err = posix_acl_create_masq(clone, mode_p);
563 if (err < 0) {
564 posix_acl_release(clone);
565 clone = NULL;
566 }
567 }
568 posix_acl_release(*acl);
569 *acl = clone;
570 return err;
571}
572EXPORT_SYMBOL(__posix_acl_create);
573
574int
575__posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
576{
577 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
578 int err = -ENOMEM;
579 if (clone) {
580 err = __posix_acl_chmod_masq(clone, mode);
581 if (err) {
582 posix_acl_release(clone);
583 clone = NULL;
584 }
585 }
586 posix_acl_release(*acl);
587 *acl = clone;
588 return err;
589}
590EXPORT_SYMBOL(__posix_acl_chmod);
591
592/**
593 * posix_acl_chmod - chmod a posix acl
594 *
595 * @idmap: idmap of the mount @inode was found from
596 * @dentry: dentry to check permissions on
597 * @mode: the new mode of @inode
598 *
599 * If the dentry has been found through an idmapped mount the idmap of
600 * the vfsmount must be passed through @idmap. This function will then
601 * take care to map the inode according to @idmap before checking
602 * permissions. On non-idmapped mounts or if permission checking is to be
603 * performed on the raw inode simply pass @nop_mnt_idmap.
604 */
605int
606 posix_acl_chmod(struct mnt_idmap *idmap, struct dentry *dentry,
607 umode_t mode)
608{
609 struct inode *inode = d_inode(dentry);
610 struct posix_acl *acl;
611 int ret = 0;
612
613 if (!IS_POSIXACL(inode))
614 return 0;
615 if (!inode->i_op->set_acl)
616 return -EOPNOTSUPP;
617
618 acl = get_inode_acl(inode, ACL_TYPE_ACCESS);
619 if (IS_ERR_OR_NULL(acl)) {
620 if (acl == ERR_PTR(-EOPNOTSUPP))
621 return 0;
622 return PTR_ERR(acl);
623 }
624
625 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
626 if (ret)
627 return ret;
628 ret = inode->i_op->set_acl(idmap, dentry, acl, ACL_TYPE_ACCESS);
629 posix_acl_release(acl);
630 return ret;
631}
632EXPORT_SYMBOL(posix_acl_chmod);
633
634int
635posix_acl_create(struct inode *dir, umode_t *mode,
636 struct posix_acl **default_acl, struct posix_acl **acl)
637{
638 struct posix_acl *p;
639 struct posix_acl *clone;
640 int ret;
641
642 *acl = NULL;
643 *default_acl = NULL;
644
645 if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
646 return 0;
647
648 p = get_inode_acl(dir, ACL_TYPE_DEFAULT);
649 if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
650 *mode &= ~current_umask();
651 return 0;
652 }
653 if (IS_ERR(p))
654 return PTR_ERR(p);
655
656 ret = -ENOMEM;
657 clone = posix_acl_clone(p, GFP_NOFS);
658 if (!clone)
659 goto err_release;
660
661 ret = posix_acl_create_masq(clone, mode);
662 if (ret < 0)
663 goto err_release_clone;
664
665 if (ret == 0)
666 posix_acl_release(clone);
667 else
668 *acl = clone;
669
670 if (!S_ISDIR(*mode))
671 posix_acl_release(p);
672 else
673 *default_acl = p;
674
675 return 0;
676
677err_release_clone:
678 posix_acl_release(clone);
679err_release:
680 posix_acl_release(p);
681 return ret;
682}
683EXPORT_SYMBOL_GPL(posix_acl_create);
684
685/**
686 * posix_acl_update_mode - update mode in set_acl
687 * @idmap: idmap of the mount @inode was found from
688 * @inode: target inode
689 * @mode_p: mode (pointer) for update
690 * @acl: acl pointer
691 *
692 * Update the file mode when setting an ACL: compute the new file permission
693 * bits based on the ACL. In addition, if the ACL is equivalent to the new
694 * file mode, set *@acl to NULL to indicate that no ACL should be set.
695 *
696 * As with chmod, clear the setgid bit if the caller is not in the owning group
697 * or capable of CAP_FSETID (see inode_change_ok).
698 *
699 * If the inode has been found through an idmapped mount the idmap of
700 * the vfsmount must be passed through @idmap. This function will then
701 * take care to map the inode according to @idmap before checking
702 * permissions. On non-idmapped mounts or if permission checking is to be
703 * performed on the raw inode simply pass @nop_mnt_idmap.
704 *
705 * Called from set_acl inode operations.
706 */
707int posix_acl_update_mode(struct mnt_idmap *idmap,
708 struct inode *inode, umode_t *mode_p,
709 struct posix_acl **acl)
710{
711 umode_t mode = inode->i_mode;
712 int error;
713
714 error = posix_acl_equiv_mode(*acl, &mode);
715 if (error < 0)
716 return error;
717 if (error == 0)
718 *acl = NULL;
719 if (!vfsgid_in_group_p(i_gid_into_vfsgid(idmap, inode)) &&
720 !capable_wrt_inode_uidgid(idmap, inode, CAP_FSETID))
721 mode &= ~S_ISGID;
722 *mode_p = mode;
723 return 0;
724}
725EXPORT_SYMBOL(posix_acl_update_mode);
726
727/*
728 * Fix up the uids and gids in posix acl extended attributes in place.
729 */
730static int posix_acl_fix_xattr_common(const void *value, size_t size)
731{
732 const struct posix_acl_xattr_header *header = value;
733 int count;
734
735 if (!header)
736 return -EINVAL;
737 if (size < sizeof(struct posix_acl_xattr_header))
738 return -EINVAL;
739 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
740 return -EOPNOTSUPP;
741
742 count = posix_acl_xattr_count(size);
743 if (count < 0)
744 return -EINVAL;
745 if (count == 0)
746 return 0;
747
748 return count;
749}
750
751/**
752 * posix_acl_from_xattr - convert POSIX ACLs from backing store to VFS format
753 * @userns: the filesystem's idmapping
754 * @value: the uapi representation of POSIX ACLs
755 * @size: the size of @void
756 *
757 * Filesystems that store POSIX ACLs in the unaltered uapi format should use
758 * posix_acl_from_xattr() when reading them from the backing store and
759 * converting them into the struct posix_acl VFS format. The helper is
760 * specifically intended to be called from the acl inode operation.
761 *
762 * The posix_acl_from_xattr() function will map the raw {g,u}id values stored
763 * in ACL_{GROUP,USER} entries into idmapping in @userns.
764 *
765 * Note that posix_acl_from_xattr() does not take idmapped mounts into account.
766 * If it did it calling it from the get acl inode operation would return POSIX
767 * ACLs mapped according to an idmapped mount which would mean that the value
768 * couldn't be cached for the filesystem. Idmapped mounts are taken into
769 * account on the fly during permission checking or right at the VFS -
770 * userspace boundary before reporting them to the user.
771 *
772 * Return: Allocated struct posix_acl on success, NULL for a valid header but
773 * without actual POSIX ACL entries, or ERR_PTR() encoded error code.
774 */
775struct posix_acl *posix_acl_from_xattr(struct user_namespace *userns,
776 const void *value, size_t size)
777{
778 const struct posix_acl_xattr_header *header = value;
779 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
780 int count;
781 struct posix_acl *acl;
782 struct posix_acl_entry *acl_e;
783
784 count = posix_acl_fix_xattr_common(value, size);
785 if (count < 0)
786 return ERR_PTR(count);
787 if (count == 0)
788 return NULL;
789
790 acl = posix_acl_alloc(count, GFP_NOFS);
791 if (!acl)
792 return ERR_PTR(-ENOMEM);
793 acl_e = acl->a_entries;
794
795 for (end = entry + count; entry != end; acl_e++, entry++) {
796 acl_e->e_tag = le16_to_cpu(entry->e_tag);
797 acl_e->e_perm = le16_to_cpu(entry->e_perm);
798
799 switch(acl_e->e_tag) {
800 case ACL_USER_OBJ:
801 case ACL_GROUP_OBJ:
802 case ACL_MASK:
803 case ACL_OTHER:
804 break;
805
806 case ACL_USER:
807 acl_e->e_uid = make_kuid(userns,
808 le32_to_cpu(entry->e_id));
809 if (!uid_valid(acl_e->e_uid))
810 goto fail;
811 break;
812 case ACL_GROUP:
813 acl_e->e_gid = make_kgid(userns,
814 le32_to_cpu(entry->e_id));
815 if (!gid_valid(acl_e->e_gid))
816 goto fail;
817 break;
818
819 default:
820 goto fail;
821 }
822 }
823 return acl;
824
825fail:
826 posix_acl_release(acl);
827 return ERR_PTR(-EINVAL);
828}
829EXPORT_SYMBOL (posix_acl_from_xattr);
830
831/*
832 * Convert from in-memory to extended attribute representation.
833 */
834int
835posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
836 void *buffer, size_t size)
837{
838 struct posix_acl_xattr_header *ext_acl = buffer;
839 struct posix_acl_xattr_entry *ext_entry;
840 int real_size, n;
841
842 real_size = posix_acl_xattr_size(acl->a_count);
843 if (!buffer)
844 return real_size;
845 if (real_size > size)
846 return -ERANGE;
847
848 ext_entry = (void *)(ext_acl + 1);
849 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
850
851 for (n=0; n < acl->a_count; n++, ext_entry++) {
852 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
853 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag);
854 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
855 switch(acl_e->e_tag) {
856 case ACL_USER:
857 ext_entry->e_id =
858 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
859 break;
860 case ACL_GROUP:
861 ext_entry->e_id =
862 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
863 break;
864 default:
865 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
866 break;
867 }
868 }
869 return real_size;
870}
871EXPORT_SYMBOL (posix_acl_to_xattr);
872
873/**
874 * vfs_posix_acl_to_xattr - convert from kernel to userspace representation
875 * @idmap: idmap of the mount
876 * @inode: inode the posix acls are set on
877 * @acl: the posix acls as represented by the vfs
878 * @buffer: the buffer into which to convert @acl
879 * @size: size of @buffer
880 *
881 * This converts @acl from the VFS representation in the filesystem idmapping
882 * to the uapi form reportable to userspace. And mount and caller idmappings
883 * are handled appropriately.
884 *
885 * Return: On success, the size of the stored uapi posix acls, on error a
886 * negative errno.
887 */
888static ssize_t vfs_posix_acl_to_xattr(struct mnt_idmap *idmap,
889 struct inode *inode,
890 const struct posix_acl *acl, void *buffer,
891 size_t size)
892
893{
894 struct posix_acl_xattr_header *ext_acl = buffer;
895 struct posix_acl_xattr_entry *ext_entry;
896 struct user_namespace *fs_userns, *caller_userns;
897 ssize_t real_size, n;
898 vfsuid_t vfsuid;
899 vfsgid_t vfsgid;
900
901 real_size = posix_acl_xattr_size(acl->a_count);
902 if (!buffer)
903 return real_size;
904 if (real_size > size)
905 return -ERANGE;
906
907 ext_entry = (void *)(ext_acl + 1);
908 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
909
910 fs_userns = i_user_ns(inode);
911 caller_userns = current_user_ns();
912 for (n=0; n < acl->a_count; n++, ext_entry++) {
913 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
914 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag);
915 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
916 switch(acl_e->e_tag) {
917 case ACL_USER:
918 vfsuid = make_vfsuid(idmap, fs_userns, acl_e->e_uid);
919 ext_entry->e_id = cpu_to_le32(from_kuid(
920 caller_userns, vfsuid_into_kuid(vfsuid)));
921 break;
922 case ACL_GROUP:
923 vfsgid = make_vfsgid(idmap, fs_userns, acl_e->e_gid);
924 ext_entry->e_id = cpu_to_le32(from_kgid(
925 caller_userns, vfsgid_into_kgid(vfsgid)));
926 break;
927 default:
928 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
929 break;
930 }
931 }
932 return real_size;
933}
934
935int
936set_posix_acl(struct mnt_idmap *idmap, struct dentry *dentry,
937 int type, struct posix_acl *acl)
938{
939 struct inode *inode = d_inode(dentry);
940
941 if (!IS_POSIXACL(inode))
942 return -EOPNOTSUPP;
943 if (!inode->i_op->set_acl)
944 return -EOPNOTSUPP;
945
946 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
947 return acl ? -EACCES : 0;
948 if (!inode_owner_or_capable(idmap, inode))
949 return -EPERM;
950
951 if (acl) {
952 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
953 if (ret)
954 return ret;
955 }
956 return inode->i_op->set_acl(idmap, dentry, acl, type);
957}
958EXPORT_SYMBOL(set_posix_acl);
959
960int posix_acl_listxattr(struct inode *inode, char **buffer,
961 ssize_t *remaining_size)
962{
963 int err;
964
965 if (!IS_POSIXACL(inode))
966 return 0;
967
968 if (inode->i_acl) {
969 err = xattr_list_one(buffer, remaining_size,
970 XATTR_NAME_POSIX_ACL_ACCESS);
971 if (err)
972 return err;
973 }
974
975 if (inode->i_default_acl) {
976 err = xattr_list_one(buffer, remaining_size,
977 XATTR_NAME_POSIX_ACL_DEFAULT);
978 if (err)
979 return err;
980 }
981
982 return 0;
983}
984
985static bool
986posix_acl_xattr_list(struct dentry *dentry)
987{
988 return IS_POSIXACL(d_backing_inode(dentry));
989}
990
991/*
992 * nop_posix_acl_access - legacy xattr handler for access POSIX ACLs
993 *
994 * This is the legacy POSIX ACL access xattr handler. It is used by some
995 * filesystems to implement their ->listxattr() inode operation. New code
996 * should never use them.
997 */
998const struct xattr_handler nop_posix_acl_access = {
999 .name = XATTR_NAME_POSIX_ACL_ACCESS,
1000 .list = posix_acl_xattr_list,
1001};
1002EXPORT_SYMBOL_GPL(nop_posix_acl_access);
1003
1004/*
1005 * nop_posix_acl_default - legacy xattr handler for default POSIX ACLs
1006 *
1007 * This is the legacy POSIX ACL default xattr handler. It is used by some
1008 * filesystems to implement their ->listxattr() inode operation. New code
1009 * should never use them.
1010 */
1011const struct xattr_handler nop_posix_acl_default = {
1012 .name = XATTR_NAME_POSIX_ACL_DEFAULT,
1013 .list = posix_acl_xattr_list,
1014};
1015EXPORT_SYMBOL_GPL(nop_posix_acl_default);
1016
1017int simple_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
1018 struct posix_acl *acl, int type)
1019{
1020 int error;
1021 struct inode *inode = d_inode(dentry);
1022
1023 if (type == ACL_TYPE_ACCESS) {
1024 error = posix_acl_update_mode(idmap, inode,
1025 &inode->i_mode, &acl);
1026 if (error)
1027 return error;
1028 }
1029
1030 inode_set_ctime_current(inode);
1031 if (IS_I_VERSION(inode))
1032 inode_inc_iversion(inode);
1033 set_cached_acl(inode, type, acl);
1034 return 0;
1035}
1036
1037int simple_acl_create(struct inode *dir, struct inode *inode)
1038{
1039 struct posix_acl *default_acl, *acl;
1040 int error;
1041
1042 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
1043 if (error)
1044 return error;
1045
1046 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
1047 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
1048
1049 if (default_acl)
1050 posix_acl_release(default_acl);
1051 if (acl)
1052 posix_acl_release(acl);
1053 return 0;
1054}
1055
1056static int vfs_set_acl_idmapped_mnt(struct mnt_idmap *idmap,
1057 struct user_namespace *fs_userns,
1058 struct posix_acl *acl)
1059{
1060 for (int n = 0; n < acl->a_count; n++) {
1061 struct posix_acl_entry *acl_e = &acl->a_entries[n];
1062
1063 switch (acl_e->e_tag) {
1064 case ACL_USER:
1065 acl_e->e_uid = from_vfsuid(idmap, fs_userns,
1066 VFSUIDT_INIT(acl_e->e_uid));
1067 break;
1068 case ACL_GROUP:
1069 acl_e->e_gid = from_vfsgid(idmap, fs_userns,
1070 VFSGIDT_INIT(acl_e->e_gid));
1071 break;
1072 }
1073 }
1074
1075 return 0;
1076}
1077
1078/**
1079 * vfs_set_acl - set posix acls
1080 * @idmap: idmap of the mount
1081 * @dentry: the dentry based on which to set the posix acls
1082 * @acl_name: the name of the posix acl
1083 * @kacl: the posix acls in the appropriate VFS format
1084 *
1085 * This function sets @kacl. The caller must all posix_acl_release() on @kacl
1086 * afterwards.
1087 *
1088 * Return: On success 0, on error negative errno.
1089 */
1090int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
1091 const char *acl_name, struct posix_acl *kacl)
1092{
1093 int acl_type;
1094 int error;
1095 struct inode *inode = d_inode(dentry);
1096 struct inode *delegated_inode = NULL;
1097
1098 acl_type = posix_acl_type(acl_name);
1099 if (acl_type < 0)
1100 return -EINVAL;
1101
1102 if (kacl) {
1103 /*
1104 * If we're on an idmapped mount translate from mount specific
1105 * vfs{g,u}id_t into global filesystem k{g,u}id_t.
1106 * Afterwards we can cache the POSIX ACLs filesystem wide and -
1107 * if this is a filesystem with a backing store - ultimately
1108 * translate them to backing store values.
1109 */
1110 error = vfs_set_acl_idmapped_mnt(idmap, i_user_ns(inode), kacl);
1111 if (error)
1112 return error;
1113 }
1114
1115retry_deleg:
1116 inode_lock(inode);
1117
1118 /*
1119 * We only care about restrictions the inode struct itself places upon
1120 * us otherwise POSIX ACLs aren't subject to any VFS restrictions.
1121 */
1122 error = may_write_xattr(idmap, inode);
1123 if (error)
1124 goto out_inode_unlock;
1125
1126 error = security_inode_set_acl(idmap, dentry, acl_name, kacl);
1127 if (error)
1128 goto out_inode_unlock;
1129
1130 error = try_break_deleg(inode, &delegated_inode);
1131 if (error)
1132 goto out_inode_unlock;
1133
1134 if (likely(!is_bad_inode(inode)))
1135 error = set_posix_acl(idmap, dentry, acl_type, kacl);
1136 else
1137 error = -EIO;
1138 if (!error) {
1139 fsnotify_xattr(dentry);
1140 evm_inode_post_set_acl(dentry, acl_name, kacl);
1141 }
1142
1143out_inode_unlock:
1144 inode_unlock(inode);
1145
1146 if (delegated_inode) {
1147 error = break_deleg_wait(&delegated_inode);
1148 if (!error)
1149 goto retry_deleg;
1150 }
1151
1152 return error;
1153}
1154EXPORT_SYMBOL_GPL(vfs_set_acl);
1155
1156/**
1157 * vfs_get_acl - get posix acls
1158 * @idmap: idmap of the mount
1159 * @dentry: the dentry based on which to retrieve the posix acls
1160 * @acl_name: the name of the posix acl
1161 *
1162 * This function retrieves @kacl from the filesystem. The caller must all
1163 * posix_acl_release() on @kacl.
1164 *
1165 * Return: On success POSIX ACLs in VFS format, on error negative errno.
1166 */
1167struct posix_acl *vfs_get_acl(struct mnt_idmap *idmap,
1168 struct dentry *dentry, const char *acl_name)
1169{
1170 struct inode *inode = d_inode(dentry);
1171 struct posix_acl *acl;
1172 int acl_type, error;
1173
1174 acl_type = posix_acl_type(acl_name);
1175 if (acl_type < 0)
1176 return ERR_PTR(-EINVAL);
1177
1178 /*
1179 * The VFS has no restrictions on reading POSIX ACLs so calling
1180 * something like xattr_permission() isn't needed. Only LSMs get a say.
1181 */
1182 error = security_inode_get_acl(idmap, dentry, acl_name);
1183 if (error)
1184 return ERR_PTR(error);
1185
1186 if (!IS_POSIXACL(inode))
1187 return ERR_PTR(-EOPNOTSUPP);
1188 if (S_ISLNK(inode->i_mode))
1189 return ERR_PTR(-EOPNOTSUPP);
1190
1191 acl = __get_acl(idmap, dentry, inode, acl_type);
1192 if (IS_ERR(acl))
1193 return acl;
1194 if (!acl)
1195 return ERR_PTR(-ENODATA);
1196
1197 return acl;
1198}
1199EXPORT_SYMBOL_GPL(vfs_get_acl);
1200
1201/**
1202 * vfs_remove_acl - remove posix acls
1203 * @idmap: idmap of the mount
1204 * @dentry: the dentry based on which to retrieve the posix acls
1205 * @acl_name: the name of the posix acl
1206 *
1207 * This function removes posix acls.
1208 *
1209 * Return: On success 0, on error negative errno.
1210 */
1211int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry,
1212 const char *acl_name)
1213{
1214 int acl_type;
1215 int error;
1216 struct inode *inode = d_inode(dentry);
1217 struct inode *delegated_inode = NULL;
1218
1219 acl_type = posix_acl_type(acl_name);
1220 if (acl_type < 0)
1221 return -EINVAL;
1222
1223retry_deleg:
1224 inode_lock(inode);
1225
1226 /*
1227 * We only care about restrictions the inode struct itself places upon
1228 * us otherwise POSIX ACLs aren't subject to any VFS restrictions.
1229 */
1230 error = may_write_xattr(idmap, inode);
1231 if (error)
1232 goto out_inode_unlock;
1233
1234 error = security_inode_remove_acl(idmap, dentry, acl_name);
1235 if (error)
1236 goto out_inode_unlock;
1237
1238 error = try_break_deleg(inode, &delegated_inode);
1239 if (error)
1240 goto out_inode_unlock;
1241
1242 if (likely(!is_bad_inode(inode)))
1243 error = set_posix_acl(idmap, dentry, acl_type, NULL);
1244 else
1245 error = -EIO;
1246 if (!error) {
1247 fsnotify_xattr(dentry);
1248 evm_inode_post_remove_acl(idmap, dentry, acl_name);
1249 }
1250
1251out_inode_unlock:
1252 inode_unlock(inode);
1253
1254 if (delegated_inode) {
1255 error = break_deleg_wait(&delegated_inode);
1256 if (!error)
1257 goto retry_deleg;
1258 }
1259
1260 return error;
1261}
1262EXPORT_SYMBOL_GPL(vfs_remove_acl);
1263
1264int do_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
1265 const char *acl_name, const void *kvalue, size_t size)
1266{
1267 int error;
1268 struct posix_acl *acl = NULL;
1269
1270 if (size) {
1271 /*
1272 * Note that posix_acl_from_xattr() uses GFP_NOFS when it
1273 * probably doesn't need to here.
1274 */
1275 acl = posix_acl_from_xattr(current_user_ns(), kvalue, size);
1276 if (IS_ERR(acl))
1277 return PTR_ERR(acl);
1278 }
1279
1280 error = vfs_set_acl(idmap, dentry, acl_name, acl);
1281 posix_acl_release(acl);
1282 return error;
1283}
1284
1285ssize_t do_get_acl(struct mnt_idmap *idmap, struct dentry *dentry,
1286 const char *acl_name, void *kvalue, size_t size)
1287{
1288 ssize_t error;
1289 struct posix_acl *acl;
1290
1291 acl = vfs_get_acl(idmap, dentry, acl_name);
1292 if (IS_ERR(acl))
1293 return PTR_ERR(acl);
1294
1295 error = vfs_posix_acl_to_xattr(idmap, d_inode(dentry),
1296 acl, kvalue, size);
1297 posix_acl_release(acl);
1298 return error;
1299}