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