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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
26static 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
38struct 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}
55EXPORT_SYMBOL(get_cached_acl);
56
57struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
58{
59 return rcu_dereference(*acl_by_type(inode, type));
60}
61EXPORT_SYMBOL(get_cached_acl_rcu);
62
63void 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}
72EXPORT_SYMBOL(set_cached_acl);
73
74static 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
83void forget_cached_acl(struct inode *inode, int type)
84{
85 __forget_cached_acl(acl_by_type(inode, type));
86}
87EXPORT_SYMBOL(forget_cached_acl);
88
89void forget_all_cached_acls(struct inode *inode)
90{
91 __forget_cached_acl(&inode->i_acl);
92 __forget_cached_acl(&inode->i_default_acl);
93}
94EXPORT_SYMBOL(forget_all_cached_acls);
95
96struct 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}
160EXPORT_SYMBOL(get_acl);
161
162/*
163 * Init a fresh posix_acl
164 */
165void
166posix_acl_init(struct posix_acl *acl, int count)
167{
168 refcount_set(&acl->a_refcount, 1);
169 acl->a_count = count;
170}
171EXPORT_SYMBOL(posix_acl_init);
172
173/*
174 * Allocate a new ACL with the specified number of entries.
175 */
176struct posix_acl *
177posix_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}
186EXPORT_SYMBOL(posix_acl_alloc);
187
188/*
189 * Clone an ACL.
190 */
191static struct posix_acl *
192posix_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 */
209int
210posix_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}
272EXPORT_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 */
278int
279posix_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}
319EXPORT_SYMBOL(posix_acl_equiv_mode);
320
321/*
322 * Create an ACL representing the file mode permission bits of an inode.
323 */
324struct posix_acl *
325posix_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}
341EXPORT_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 */
347int
348posix_acl_permission(struct user_namespace *mnt_userns, struct inode *inode,
349 const struct posix_acl *acl, int want)
350{
351 const struct posix_acl_entry *pa, *pe, *mask_obj;
352 int found = 0;
353 kuid_t uid;
354 kgid_t gid;
355
356 want &= MAY_READ | MAY_WRITE | MAY_EXEC;
357
358 FOREACH_ACL_ENTRY(pa, acl, pe) {
359 switch(pa->e_tag) {
360 case ACL_USER_OBJ:
361 /* (May have been checked already) */
362 uid = i_uid_into_mnt(mnt_userns, inode);
363 if (uid_eq(uid, current_fsuid()))
364 goto check_perm;
365 break;
366 case ACL_USER:
367 uid = kuid_into_mnt(mnt_userns, pa->e_uid);
368 if (uid_eq(uid, current_fsuid()))
369 goto mask;
370 break;
371 case ACL_GROUP_OBJ:
372 gid = i_gid_into_mnt(mnt_userns, inode);
373 if (in_group_p(gid)) {
374 found = 1;
375 if ((pa->e_perm & want) == want)
376 goto mask;
377 }
378 break;
379 case ACL_GROUP:
380 gid = kgid_into_mnt(mnt_userns, pa->e_gid);
381 if (in_group_p(gid)) {
382 found = 1;
383 if ((pa->e_perm & want) == want)
384 goto mask;
385 }
386 break;
387 case ACL_MASK:
388 break;
389 case ACL_OTHER:
390 if (found)
391 return -EACCES;
392 else
393 goto check_perm;
394 default:
395 return -EIO;
396 }
397 }
398 return -EIO;
399
400mask:
401 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
402 if (mask_obj->e_tag == ACL_MASK) {
403 if ((pa->e_perm & mask_obj->e_perm & want) == want)
404 return 0;
405 return -EACCES;
406 }
407 }
408
409check_perm:
410 if ((pa->e_perm & want) == want)
411 return 0;
412 return -EACCES;
413}
414
415/*
416 * Modify acl when creating a new inode. The caller must ensure the acl is
417 * only referenced once.
418 *
419 * mode_p initially must contain the mode parameter to the open() / creat()
420 * system calls. All permissions that are not granted by the acl are removed.
421 * The permissions in the acl are changed to reflect the mode_p parameter.
422 */
423static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
424{
425 struct posix_acl_entry *pa, *pe;
426 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
427 umode_t mode = *mode_p;
428 int not_equiv = 0;
429
430 /* assert(atomic_read(acl->a_refcount) == 1); */
431
432 FOREACH_ACL_ENTRY(pa, acl, pe) {
433 switch(pa->e_tag) {
434 case ACL_USER_OBJ:
435 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
436 mode &= (pa->e_perm << 6) | ~S_IRWXU;
437 break;
438
439 case ACL_USER:
440 case ACL_GROUP:
441 not_equiv = 1;
442 break;
443
444 case ACL_GROUP_OBJ:
445 group_obj = pa;
446 break;
447
448 case ACL_OTHER:
449 pa->e_perm &= mode | ~S_IRWXO;
450 mode &= pa->e_perm | ~S_IRWXO;
451 break;
452
453 case ACL_MASK:
454 mask_obj = pa;
455 not_equiv = 1;
456 break;
457
458 default:
459 return -EIO;
460 }
461 }
462
463 if (mask_obj) {
464 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
465 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
466 } else {
467 if (!group_obj)
468 return -EIO;
469 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
470 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
471 }
472
473 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
474 return not_equiv;
475}
476
477/*
478 * Modify the ACL for the chmod syscall.
479 */
480static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
481{
482 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
483 struct posix_acl_entry *pa, *pe;
484
485 /* assert(atomic_read(acl->a_refcount) == 1); */
486
487 FOREACH_ACL_ENTRY(pa, acl, pe) {
488 switch(pa->e_tag) {
489 case ACL_USER_OBJ:
490 pa->e_perm = (mode & S_IRWXU) >> 6;
491 break;
492
493 case ACL_USER:
494 case ACL_GROUP:
495 break;
496
497 case ACL_GROUP_OBJ:
498 group_obj = pa;
499 break;
500
501 case ACL_MASK:
502 mask_obj = pa;
503 break;
504
505 case ACL_OTHER:
506 pa->e_perm = (mode & S_IRWXO);
507 break;
508
509 default:
510 return -EIO;
511 }
512 }
513
514 if (mask_obj) {
515 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
516 } else {
517 if (!group_obj)
518 return -EIO;
519 group_obj->e_perm = (mode & S_IRWXG) >> 3;
520 }
521
522 return 0;
523}
524
525int
526__posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
527{
528 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
529 int err = -ENOMEM;
530 if (clone) {
531 err = posix_acl_create_masq(clone, mode_p);
532 if (err < 0) {
533 posix_acl_release(clone);
534 clone = NULL;
535 }
536 }
537 posix_acl_release(*acl);
538 *acl = clone;
539 return err;
540}
541EXPORT_SYMBOL(__posix_acl_create);
542
543int
544__posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
545{
546 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
547 int err = -ENOMEM;
548 if (clone) {
549 err = __posix_acl_chmod_masq(clone, mode);
550 if (err) {
551 posix_acl_release(clone);
552 clone = NULL;
553 }
554 }
555 posix_acl_release(*acl);
556 *acl = clone;
557 return err;
558}
559EXPORT_SYMBOL(__posix_acl_chmod);
560
561/**
562 * posix_acl_chmod - chmod a posix acl
563 *
564 * @mnt_userns: user namespace of the mount @inode was found from
565 * @inode: inode to check permissions on
566 * @mode: the new mode of @inode
567 *
568 * If the inode has been found through an idmapped mount the user namespace of
569 * the vfsmount must be passed through @mnt_userns. This function will then
570 * take care to map the inode according to @mnt_userns before checking
571 * permissions. On non-idmapped mounts or if permission checking is to be
572 * performed on the raw inode simply passs init_user_ns.
573 */
574int
575 posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode,
576 umode_t mode)
577{
578 struct posix_acl *acl;
579 int ret = 0;
580
581 if (!IS_POSIXACL(inode))
582 return 0;
583 if (!inode->i_op->set_acl)
584 return -EOPNOTSUPP;
585
586 acl = get_acl(inode, ACL_TYPE_ACCESS);
587 if (IS_ERR_OR_NULL(acl)) {
588 if (acl == ERR_PTR(-EOPNOTSUPP))
589 return 0;
590 return PTR_ERR(acl);
591 }
592
593 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
594 if (ret)
595 return ret;
596 ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS);
597 posix_acl_release(acl);
598 return ret;
599}
600EXPORT_SYMBOL(posix_acl_chmod);
601
602int
603posix_acl_create(struct inode *dir, umode_t *mode,
604 struct posix_acl **default_acl, struct posix_acl **acl)
605{
606 struct posix_acl *p;
607 struct posix_acl *clone;
608 int ret;
609
610 *acl = NULL;
611 *default_acl = NULL;
612
613 if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
614 return 0;
615
616 p = get_acl(dir, ACL_TYPE_DEFAULT);
617 if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
618 *mode &= ~current_umask();
619 return 0;
620 }
621 if (IS_ERR(p))
622 return PTR_ERR(p);
623
624 ret = -ENOMEM;
625 clone = posix_acl_clone(p, GFP_NOFS);
626 if (!clone)
627 goto err_release;
628
629 ret = posix_acl_create_masq(clone, mode);
630 if (ret < 0)
631 goto err_release_clone;
632
633 if (ret == 0)
634 posix_acl_release(clone);
635 else
636 *acl = clone;
637
638 if (!S_ISDIR(*mode))
639 posix_acl_release(p);
640 else
641 *default_acl = p;
642
643 return 0;
644
645err_release_clone:
646 posix_acl_release(clone);
647err_release:
648 posix_acl_release(p);
649 return ret;
650}
651EXPORT_SYMBOL_GPL(posix_acl_create);
652
653/**
654 * posix_acl_update_mode - update mode in set_acl
655 * @mnt_userns: user namespace of the mount @inode was found from
656 * @inode: target inode
657 * @mode_p: mode (pointer) for update
658 * @acl: acl pointer
659 *
660 * Update the file mode when setting an ACL: compute the new file permission
661 * bits based on the ACL. In addition, if the ACL is equivalent to the new
662 * file mode, set *@acl to NULL to indicate that no ACL should be set.
663 *
664 * As with chmod, clear the setgid bit if the caller is not in the owning group
665 * or capable of CAP_FSETID (see inode_change_ok).
666 *
667 * If the inode has been found through an idmapped mount the user namespace of
668 * the vfsmount must be passed through @mnt_userns. This function will then
669 * take care to map the inode according to @mnt_userns before checking
670 * permissions. On non-idmapped mounts or if permission checking is to be
671 * performed on the raw inode simply passs init_user_ns.
672 *
673 * Called from set_acl inode operations.
674 */
675int posix_acl_update_mode(struct user_namespace *mnt_userns,
676 struct inode *inode, umode_t *mode_p,
677 struct posix_acl **acl)
678{
679 umode_t mode = inode->i_mode;
680 int error;
681
682 error = posix_acl_equiv_mode(*acl, &mode);
683 if (error < 0)
684 return error;
685 if (error == 0)
686 *acl = NULL;
687 if (!in_group_p(i_gid_into_mnt(mnt_userns, inode)) &&
688 !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
689 mode &= ~S_ISGID;
690 *mode_p = mode;
691 return 0;
692}
693EXPORT_SYMBOL(posix_acl_update_mode);
694
695/*
696 * Fix up the uids and gids in posix acl extended attributes in place.
697 */
698static void posix_acl_fix_xattr_userns(
699 struct user_namespace *to, struct user_namespace *from,
700 struct user_namespace *mnt_userns,
701 void *value, size_t size, bool from_user)
702{
703 struct posix_acl_xattr_header *header = value;
704 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
705 int count;
706 kuid_t uid;
707 kgid_t gid;
708
709 if (!value)
710 return;
711 if (size < sizeof(struct posix_acl_xattr_header))
712 return;
713 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
714 return;
715
716 count = posix_acl_xattr_count(size);
717 if (count < 0)
718 return;
719 if (count == 0)
720 return;
721
722 for (end = entry + count; entry != end; entry++) {
723 switch(le16_to_cpu(entry->e_tag)) {
724 case ACL_USER:
725 uid = make_kuid(from, le32_to_cpu(entry->e_id));
726 if (from_user)
727 uid = kuid_from_mnt(mnt_userns, uid);
728 else
729 uid = kuid_into_mnt(mnt_userns, uid);
730 entry->e_id = cpu_to_le32(from_kuid(to, uid));
731 break;
732 case ACL_GROUP:
733 gid = make_kgid(from, le32_to_cpu(entry->e_id));
734 if (from_user)
735 gid = kgid_from_mnt(mnt_userns, gid);
736 else
737 gid = kgid_into_mnt(mnt_userns, gid);
738 entry->e_id = cpu_to_le32(from_kgid(to, gid));
739 break;
740 default:
741 break;
742 }
743 }
744}
745
746void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns,
747 void *value, size_t size)
748{
749 struct user_namespace *user_ns = current_user_ns();
750 if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
751 return;
752 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, mnt_userns, value,
753 size, true);
754}
755
756void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns,
757 void *value, size_t size)
758{
759 struct user_namespace *user_ns = current_user_ns();
760 if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
761 return;
762 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, mnt_userns, value,
763 size, false);
764}
765
766/*
767 * Convert from extended attribute to in-memory representation.
768 */
769struct posix_acl *
770posix_acl_from_xattr(struct user_namespace *user_ns,
771 const void *value, size_t size)
772{
773 const struct posix_acl_xattr_header *header = value;
774 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
775 int count;
776 struct posix_acl *acl;
777 struct posix_acl_entry *acl_e;
778
779 if (!value)
780 return NULL;
781 if (size < sizeof(struct posix_acl_xattr_header))
782 return ERR_PTR(-EINVAL);
783 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
784 return ERR_PTR(-EOPNOTSUPP);
785
786 count = posix_acl_xattr_count(size);
787 if (count < 0)
788 return ERR_PTR(-EINVAL);
789 if (count == 0)
790 return NULL;
791
792 acl = posix_acl_alloc(count, GFP_NOFS);
793 if (!acl)
794 return ERR_PTR(-ENOMEM);
795 acl_e = acl->a_entries;
796
797 for (end = entry + count; entry != end; acl_e++, entry++) {
798 acl_e->e_tag = le16_to_cpu(entry->e_tag);
799 acl_e->e_perm = le16_to_cpu(entry->e_perm);
800
801 switch(acl_e->e_tag) {
802 case ACL_USER_OBJ:
803 case ACL_GROUP_OBJ:
804 case ACL_MASK:
805 case ACL_OTHER:
806 break;
807
808 case ACL_USER:
809 acl_e->e_uid =
810 make_kuid(user_ns,
811 le32_to_cpu(entry->e_id));
812 if (!uid_valid(acl_e->e_uid))
813 goto fail;
814 break;
815 case ACL_GROUP:
816 acl_e->e_gid =
817 make_kgid(user_ns,
818 le32_to_cpu(entry->e_id));
819 if (!gid_valid(acl_e->e_gid))
820 goto fail;
821 break;
822
823 default:
824 goto fail;
825 }
826 }
827 return acl;
828
829fail:
830 posix_acl_release(acl);
831 return ERR_PTR(-EINVAL);
832}
833EXPORT_SYMBOL (posix_acl_from_xattr);
834
835/*
836 * Convert from in-memory to extended attribute representation.
837 */
838int
839posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
840 void *buffer, size_t size)
841{
842 struct posix_acl_xattr_header *ext_acl = buffer;
843 struct posix_acl_xattr_entry *ext_entry;
844 int real_size, n;
845
846 real_size = posix_acl_xattr_size(acl->a_count);
847 if (!buffer)
848 return real_size;
849 if (real_size > size)
850 return -ERANGE;
851
852 ext_entry = (void *)(ext_acl + 1);
853 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
854
855 for (n=0; n < acl->a_count; n++, ext_entry++) {
856 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
857 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag);
858 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
859 switch(acl_e->e_tag) {
860 case ACL_USER:
861 ext_entry->e_id =
862 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
863 break;
864 case ACL_GROUP:
865 ext_entry->e_id =
866 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
867 break;
868 default:
869 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
870 break;
871 }
872 }
873 return real_size;
874}
875EXPORT_SYMBOL (posix_acl_to_xattr);
876
877static int
878posix_acl_xattr_get(const struct xattr_handler *handler,
879 struct dentry *unused, struct inode *inode,
880 const char *name, void *value, size_t size)
881{
882 struct posix_acl *acl;
883 int error;
884
885 if (!IS_POSIXACL(inode))
886 return -EOPNOTSUPP;
887 if (S_ISLNK(inode->i_mode))
888 return -EOPNOTSUPP;
889
890 acl = get_acl(inode, handler->flags);
891 if (IS_ERR(acl))
892 return PTR_ERR(acl);
893 if (acl == NULL)
894 return -ENODATA;
895
896 error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
897 posix_acl_release(acl);
898
899 return error;
900}
901
902int
903set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode,
904 int type, struct posix_acl *acl)
905{
906 if (!IS_POSIXACL(inode))
907 return -EOPNOTSUPP;
908 if (!inode->i_op->set_acl)
909 return -EOPNOTSUPP;
910
911 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
912 return acl ? -EACCES : 0;
913 if (!inode_owner_or_capable(mnt_userns, inode))
914 return -EPERM;
915
916 if (acl) {
917 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
918 if (ret)
919 return ret;
920 }
921 return inode->i_op->set_acl(mnt_userns, inode, acl, type);
922}
923EXPORT_SYMBOL(set_posix_acl);
924
925static int
926posix_acl_xattr_set(const struct xattr_handler *handler,
927 struct user_namespace *mnt_userns,
928 struct dentry *unused, struct inode *inode,
929 const char *name, const void *value, size_t size,
930 int flags)
931{
932 struct posix_acl *acl = NULL;
933 int ret;
934
935 if (value) {
936 acl = posix_acl_from_xattr(&init_user_ns, value, size);
937 if (IS_ERR(acl))
938 return PTR_ERR(acl);
939 }
940 ret = set_posix_acl(mnt_userns, inode, handler->flags, acl);
941 posix_acl_release(acl);
942 return ret;
943}
944
945static bool
946posix_acl_xattr_list(struct dentry *dentry)
947{
948 return IS_POSIXACL(d_backing_inode(dentry));
949}
950
951const struct xattr_handler posix_acl_access_xattr_handler = {
952 .name = XATTR_NAME_POSIX_ACL_ACCESS,
953 .flags = ACL_TYPE_ACCESS,
954 .list = posix_acl_xattr_list,
955 .get = posix_acl_xattr_get,
956 .set = posix_acl_xattr_set,
957};
958EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
959
960const struct xattr_handler posix_acl_default_xattr_handler = {
961 .name = XATTR_NAME_POSIX_ACL_DEFAULT,
962 .flags = ACL_TYPE_DEFAULT,
963 .list = posix_acl_xattr_list,
964 .get = posix_acl_xattr_get,
965 .set = posix_acl_xattr_set,
966};
967EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
968
969int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
970 struct posix_acl *acl, int type)
971{
972 int error;
973
974 if (type == ACL_TYPE_ACCESS) {
975 error = posix_acl_update_mode(mnt_userns, inode,
976 &inode->i_mode, &acl);
977 if (error)
978 return error;
979 }
980
981 inode->i_ctime = current_time(inode);
982 set_cached_acl(inode, type, acl);
983 return 0;
984}
985
986int simple_acl_create(struct inode *dir, struct inode *inode)
987{
988 struct posix_acl *default_acl, *acl;
989 int error;
990
991 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
992 if (error)
993 return error;
994
995 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
996 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
997
998 if (default_acl)
999 posix_acl_release(default_acl);
1000 if (acl)
1001 posix_acl_release(acl);
1002 return 0;
1003}