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