1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2002,2003 by Andreas Gruenbacher <a.gruenbacher@computer.org>
4 *
5 * Fixes from William Schumacher incorporated on 15 March 2001.
6 * (Reported by Charles Bertsch, <CBertsch@microtest.com>).
7 */
8
9 /*
10 * This file contains generic functions for manipulating
11 * POSIX 1003.1e draft standard 17 ACLs.
12 */
13
14 #include <linux/kernel.h>
15 #include <linux/slab.h>
16 #include <linux/atomic.h>
17 #include <linux/fs.h>
18 #include <linux/sched.h>
19 #include <linux/cred.h>
20 #include <linux/posix_acl.h>
21 #include <linux/posix_acl_xattr.h>
22 #include <linux/xattr.h>
23 #include <linux/export.h>
24 #include <linux/user_namespace.h>
25 #include <linux/namei.h>
26
acl_by_type(struct inode * inode,int type)27 static struct posix_acl **acl_by_type(struct inode *inode, int type)
28 {
29 switch (type) {
30 case ACL_TYPE_ACCESS:
31 return &inode->i_acl;
32 case ACL_TYPE_DEFAULT:
33 return &inode->i_default_acl;
34 default:
35 BUG();
36 }
37 }
38
get_cached_acl(struct inode * inode,int type)39 struct posix_acl *get_cached_acl(struct inode *inode, int type)
40 {
41 struct posix_acl **p = acl_by_type(inode, type);
42 struct posix_acl *acl;
43
44 for (;;) {
45 rcu_read_lock();
46 acl = rcu_dereference(*p);
47 if (!acl || is_uncached_acl(acl) ||
48 refcount_inc_not_zero(&acl->a_refcount))
49 break;
50 rcu_read_unlock();
51 cpu_relax();
52 }
53 rcu_read_unlock();
54 return acl;
55 }
56 EXPORT_SYMBOL(get_cached_acl);
57
get_cached_acl_rcu(struct inode * inode,int type)58 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
59 {
60 struct posix_acl *acl = rcu_dereference(*acl_by_type(inode, type));
61
62 if (acl == ACL_DONT_CACHE) {
63 struct posix_acl *ret;
64
65 ret = inode->i_op->get_acl(inode, type, LOOKUP_RCU);
66 if (!IS_ERR(ret))
67 acl = ret;
68 }
69
70 return acl;
71 }
72 EXPORT_SYMBOL(get_cached_acl_rcu);
73
set_cached_acl(struct inode * inode,int type,struct posix_acl * acl)74 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
75 {
76 struct posix_acl **p = acl_by_type(inode, type);
77 struct posix_acl *old;
78
79 old = xchg(p, posix_acl_dup(acl));
80 if (!is_uncached_acl(old))
81 posix_acl_release(old);
82 }
83 EXPORT_SYMBOL(set_cached_acl);
84
__forget_cached_acl(struct posix_acl ** p)85 static void __forget_cached_acl(struct posix_acl **p)
86 {
87 struct posix_acl *old;
88
89 old = xchg(p, ACL_NOT_CACHED);
90 if (!is_uncached_acl(old))
91 posix_acl_release(old);
92 }
93
forget_cached_acl(struct inode * inode,int type)94 void forget_cached_acl(struct inode *inode, int type)
95 {
96 __forget_cached_acl(acl_by_type(inode, type));
97 }
98 EXPORT_SYMBOL(forget_cached_acl);
99
forget_all_cached_acls(struct inode * inode)100 void forget_all_cached_acls(struct inode *inode)
101 {
102 __forget_cached_acl(&inode->i_acl);
103 __forget_cached_acl(&inode->i_default_acl);
104 }
105 EXPORT_SYMBOL(forget_all_cached_acls);
106
get_acl(struct inode * inode,int type)107 struct posix_acl *get_acl(struct inode *inode, int type)
108 {
109 void *sentinel;
110 struct posix_acl **p;
111 struct posix_acl *acl;
112
113 /*
114 * The sentinel is used to detect when another operation like
115 * set_cached_acl() or forget_cached_acl() races with get_acl().
116 * It is guaranteed that is_uncached_acl(sentinel) is true.
117 */
118
119 acl = get_cached_acl(inode, type);
120 if (!is_uncached_acl(acl))
121 return acl;
122
123 if (!IS_POSIXACL(inode))
124 return NULL;
125
126 sentinel = uncached_acl_sentinel(current);
127 p = acl_by_type(inode, type);
128
129 /*
130 * If the ACL isn't being read yet, set our sentinel. Otherwise, the
131 * current value of the ACL will not be ACL_NOT_CACHED and so our own
132 * sentinel will not be set; another task will update the cache. We
133 * could wait for that other task to complete its job, but it's easier
134 * to just call ->get_acl to fetch the ACL ourself. (This is going to
135 * be an unlikely race.)
136 */
137 if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED)
138 /* fall through */ ;
139
140 /*
141 * Normally, the ACL returned by ->get_acl will be cached.
142 * A filesystem can prevent that by calling
143 * forget_cached_acl(inode, type) in ->get_acl.
144 *
145 * If the filesystem doesn't have a get_acl() function at all, we'll
146 * just create the negative cache entry.
147 */
148 if (!inode->i_op->get_acl) {
149 set_cached_acl(inode, type, NULL);
150 return NULL;
151 }
152 acl = inode->i_op->get_acl(inode, type, false);
153
154 if (IS_ERR(acl)) {
155 /*
156 * Remove our sentinel so that we don't block future attempts
157 * to cache the ACL.
158 */
159 cmpxchg(p, sentinel, ACL_NOT_CACHED);
160 return acl;
161 }
162
163 /*
164 * Cache the result, but only if our sentinel is still in place.
165 */
166 posix_acl_dup(acl);
167 if (unlikely(cmpxchg(p, sentinel, acl) != sentinel))
168 posix_acl_release(acl);
169 return acl;
170 }
171 EXPORT_SYMBOL(get_acl);
172
173 /*
174 * Init a fresh posix_acl
175 */
176 void
posix_acl_init(struct posix_acl * acl,int count)177 posix_acl_init(struct posix_acl *acl, int count)
178 {
179 refcount_set(&acl->a_refcount, 1);
180 acl->a_count = count;
181 }
182 EXPORT_SYMBOL(posix_acl_init);
183
184 /*
185 * Allocate a new ACL with the specified number of entries.
186 */
187 struct posix_acl *
posix_acl_alloc(int count,gfp_t flags)188 posix_acl_alloc(int count, gfp_t flags)
189 {
190 const size_t size = sizeof(struct posix_acl) +
191 count * sizeof(struct posix_acl_entry);
192 struct posix_acl *acl = kmalloc(size, flags);
193 if (acl)
194 posix_acl_init(acl, count);
195 return acl;
196 }
197 EXPORT_SYMBOL(posix_acl_alloc);
198
199 /*
200 * Clone an ACL.
201 */
202 static struct posix_acl *
posix_acl_clone(const struct posix_acl * acl,gfp_t flags)203 posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
204 {
205 struct posix_acl *clone = NULL;
206
207 if (acl) {
208 int size = sizeof(struct posix_acl) + acl->a_count *
209 sizeof(struct posix_acl_entry);
210 clone = kmemdup(acl, size, flags);
211 if (clone)
212 refcount_set(&clone->a_refcount, 1);
213 }
214 return clone;
215 }
216
217 /*
218 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
219 */
220 int
posix_acl_valid(struct user_namespace * user_ns,const struct posix_acl * acl)221 posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl)
222 {
223 const struct posix_acl_entry *pa, *pe;
224 int state = ACL_USER_OBJ;
225 int needs_mask = 0;
226
227 FOREACH_ACL_ENTRY(pa, acl, pe) {
228 if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
229 return -EINVAL;
230 switch (pa->e_tag) {
231 case ACL_USER_OBJ:
232 if (state == ACL_USER_OBJ) {
233 state = ACL_USER;
234 break;
235 }
236 return -EINVAL;
237
238 case ACL_USER:
239 if (state != ACL_USER)
240 return -EINVAL;
241 if (!kuid_has_mapping(user_ns, pa->e_uid))
242 return -EINVAL;
243 needs_mask = 1;
244 break;
245
246 case ACL_GROUP_OBJ:
247 if (state == ACL_USER) {
248 state = ACL_GROUP;
249 break;
250 }
251 return -EINVAL;
252
253 case ACL_GROUP:
254 if (state != ACL_GROUP)
255 return -EINVAL;
256 if (!kgid_has_mapping(user_ns, pa->e_gid))
257 return -EINVAL;
258 needs_mask = 1;
259 break;
260
261 case ACL_MASK:
262 if (state != ACL_GROUP)
263 return -EINVAL;
264 state = ACL_OTHER;
265 break;
266
267 case ACL_OTHER:
268 if (state == ACL_OTHER ||
269 (state == ACL_GROUP && !needs_mask)) {
270 state = 0;
271 break;
272 }
273 return -EINVAL;
274
275 default:
276 return -EINVAL;
277 }
278 }
279 if (state == 0)
280 return 0;
281 return -EINVAL;
282 }
283 EXPORT_SYMBOL(posix_acl_valid);
284
285 /*
286 * Returns 0 if the acl can be exactly represented in the traditional
287 * file mode permission bits, or else 1. Returns -E... on error.
288 */
289 int
posix_acl_equiv_mode(const struct posix_acl * acl,umode_t * mode_p)290 posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p)
291 {
292 const struct posix_acl_entry *pa, *pe;
293 umode_t mode = 0;
294 int not_equiv = 0;
295
296 /*
297 * A null ACL can always be presented as mode bits.
298 */
299 if (!acl)
300 return 0;
301
302 FOREACH_ACL_ENTRY(pa, acl, pe) {
303 switch (pa->e_tag) {
304 case ACL_USER_OBJ:
305 mode |= (pa->e_perm & S_IRWXO) << 6;
306 break;
307 case ACL_GROUP_OBJ:
308 mode |= (pa->e_perm & S_IRWXO) << 3;
309 break;
310 case ACL_OTHER:
311 mode |= pa->e_perm & S_IRWXO;
312 break;
313 case ACL_MASK:
314 mode = (mode & ~S_IRWXG) |
315 ((pa->e_perm & S_IRWXO) << 3);
316 not_equiv = 1;
317 break;
318 case ACL_USER:
319 case ACL_GROUP:
320 not_equiv = 1;
321 break;
322 default:
323 return -EINVAL;
324 }
325 }
326 if (mode_p)
327 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
328 return not_equiv;
329 }
330 EXPORT_SYMBOL(posix_acl_equiv_mode);
331
332 /*
333 * Create an ACL representing the file mode permission bits of an inode.
334 */
335 struct posix_acl *
posix_acl_from_mode(umode_t mode,gfp_t flags)336 posix_acl_from_mode(umode_t mode, gfp_t flags)
337 {
338 struct posix_acl *acl = posix_acl_alloc(3, flags);
339 if (!acl)
340 return ERR_PTR(-ENOMEM);
341
342 acl->a_entries[0].e_tag = ACL_USER_OBJ;
343 acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
344
345 acl->a_entries[1].e_tag = ACL_GROUP_OBJ;
346 acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
347
348 acl->a_entries[2].e_tag = ACL_OTHER;
349 acl->a_entries[2].e_perm = (mode & S_IRWXO);
350 return acl;
351 }
352 EXPORT_SYMBOL(posix_acl_from_mode);
353
354 /*
355 * Return 0 if current is granted want access to the inode
356 * by the acl. Returns -E... otherwise.
357 */
358 int
posix_acl_permission(struct user_namespace * mnt_userns,struct inode * inode,const struct posix_acl * acl,int want)359 posix_acl_permission(struct user_namespace *mnt_userns, struct inode *inode,
360 const struct posix_acl *acl, int want)
361 {
362 const struct posix_acl_entry *pa, *pe, *mask_obj;
363 int found = 0;
364 kuid_t uid;
365 kgid_t gid;
366
367 want &= MAY_READ | MAY_WRITE | MAY_EXEC;
368
369 FOREACH_ACL_ENTRY(pa, acl, pe) {
370 switch(pa->e_tag) {
371 case ACL_USER_OBJ:
372 /* (May have been checked already) */
373 uid = i_uid_into_mnt(mnt_userns, inode);
374 if (uid_eq(uid, current_fsuid()))
375 goto check_perm;
376 break;
377 case ACL_USER:
378 uid = kuid_into_mnt(mnt_userns, pa->e_uid);
379 if (uid_eq(uid, current_fsuid()))
380 goto mask;
381 break;
382 case ACL_GROUP_OBJ:
383 gid = i_gid_into_mnt(mnt_userns, inode);
384 if (in_group_p(gid)) {
385 found = 1;
386 if ((pa->e_perm & want) == want)
387 goto mask;
388 }
389 break;
390 case ACL_GROUP:
391 gid = kgid_into_mnt(mnt_userns, pa->e_gid);
392 if (in_group_p(gid)) {
393 found = 1;
394 if ((pa->e_perm & want) == want)
395 goto mask;
396 }
397 break;
398 case ACL_MASK:
399 break;
400 case ACL_OTHER:
401 if (found)
402 return -EACCES;
403 else
404 goto check_perm;
405 default:
406 return -EIO;
407 }
408 }
409 return -EIO;
410
411 mask:
412 for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
413 if (mask_obj->e_tag == ACL_MASK) {
414 if ((pa->e_perm & mask_obj->e_perm & want) == want)
415 return 0;
416 return -EACCES;
417 }
418 }
419
420 check_perm:
421 if ((pa->e_perm & want) == want)
422 return 0;
423 return -EACCES;
424 }
425
426 /*
427 * Modify acl when creating a new inode. The caller must ensure the acl is
428 * only referenced once.
429 *
430 * mode_p initially must contain the mode parameter to the open() / creat()
431 * system calls. All permissions that are not granted by the acl are removed.
432 * The permissions in the acl are changed to reflect the mode_p parameter.
433 */
posix_acl_create_masq(struct posix_acl * acl,umode_t * mode_p)434 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
435 {
436 struct posix_acl_entry *pa, *pe;
437 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
438 umode_t mode = *mode_p;
439 int not_equiv = 0;
440
441 /* assert(atomic_read(acl->a_refcount) == 1); */
442
443 FOREACH_ACL_ENTRY(pa, acl, pe) {
444 switch(pa->e_tag) {
445 case ACL_USER_OBJ:
446 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
447 mode &= (pa->e_perm << 6) | ~S_IRWXU;
448 break;
449
450 case ACL_USER:
451 case ACL_GROUP:
452 not_equiv = 1;
453 break;
454
455 case ACL_GROUP_OBJ:
456 group_obj = pa;
457 break;
458
459 case ACL_OTHER:
460 pa->e_perm &= mode | ~S_IRWXO;
461 mode &= pa->e_perm | ~S_IRWXO;
462 break;
463
464 case ACL_MASK:
465 mask_obj = pa;
466 not_equiv = 1;
467 break;
468
469 default:
470 return -EIO;
471 }
472 }
473
474 if (mask_obj) {
475 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
476 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
477 } else {
478 if (!group_obj)
479 return -EIO;
480 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
481 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
482 }
483
484 *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
485 return not_equiv;
486 }
487
488 /*
489 * Modify the ACL for the chmod syscall.
490 */
__posix_acl_chmod_masq(struct posix_acl * acl,umode_t mode)491 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
492 {
493 struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
494 struct posix_acl_entry *pa, *pe;
495
496 /* assert(atomic_read(acl->a_refcount) == 1); */
497
498 FOREACH_ACL_ENTRY(pa, acl, pe) {
499 switch(pa->e_tag) {
500 case ACL_USER_OBJ:
501 pa->e_perm = (mode & S_IRWXU) >> 6;
502 break;
503
504 case ACL_USER:
505 case ACL_GROUP:
506 break;
507
508 case ACL_GROUP_OBJ:
509 group_obj = pa;
510 break;
511
512 case ACL_MASK:
513 mask_obj = pa;
514 break;
515
516 case ACL_OTHER:
517 pa->e_perm = (mode & S_IRWXO);
518 break;
519
520 default:
521 return -EIO;
522 }
523 }
524
525 if (mask_obj) {
526 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
527 } else {
528 if (!group_obj)
529 return -EIO;
530 group_obj->e_perm = (mode & S_IRWXG) >> 3;
531 }
532
533 return 0;
534 }
535
536 int
__posix_acl_create(struct posix_acl ** acl,gfp_t gfp,umode_t * mode_p)537 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
538 {
539 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
540 int err = -ENOMEM;
541 if (clone) {
542 err = posix_acl_create_masq(clone, mode_p);
543 if (err < 0) {
544 posix_acl_release(clone);
545 clone = NULL;
546 }
547 }
548 posix_acl_release(*acl);
549 *acl = clone;
550 return err;
551 }
552 EXPORT_SYMBOL(__posix_acl_create);
553
554 int
__posix_acl_chmod(struct posix_acl ** acl,gfp_t gfp,umode_t mode)555 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
556 {
557 struct posix_acl *clone = posix_acl_clone(*acl, gfp);
558 int err = -ENOMEM;
559 if (clone) {
560 err = __posix_acl_chmod_masq(clone, mode);
561 if (err) {
562 posix_acl_release(clone);
563 clone = NULL;
564 }
565 }
566 posix_acl_release(*acl);
567 *acl = clone;
568 return err;
569 }
570 EXPORT_SYMBOL(__posix_acl_chmod);
571
572 /**
573 * posix_acl_chmod - chmod a posix acl
574 *
575 * @mnt_userns: user namespace of the mount @inode was found from
576 * @inode: inode to check permissions on
577 * @mode: the new mode of @inode
578 *
579 * If the inode has been found through an idmapped mount the user namespace of
580 * the vfsmount must be passed through @mnt_userns. This function will then
581 * take care to map the inode according to @mnt_userns before checking
582 * permissions. On non-idmapped mounts or if permission checking is to be
583 * performed on the raw inode simply passs init_user_ns.
584 */
585 int
posix_acl_chmod(struct user_namespace * mnt_userns,struct inode * inode,umode_t mode)586 posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode,
587 umode_t mode)
588 {
589 struct posix_acl *acl;
590 int ret = 0;
591
592 if (!IS_POSIXACL(inode))
593 return 0;
594 if (!inode->i_op->set_acl)
595 return -EOPNOTSUPP;
596
597 acl = get_acl(inode, ACL_TYPE_ACCESS);
598 if (IS_ERR_OR_NULL(acl)) {
599 if (acl == ERR_PTR(-EOPNOTSUPP))
600 return 0;
601 return PTR_ERR(acl);
602 }
603
604 ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
605 if (ret)
606 return ret;
607 ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS);
608 posix_acl_release(acl);
609 return ret;
610 }
611 EXPORT_SYMBOL(posix_acl_chmod);
612
613 int
posix_acl_create(struct inode * dir,umode_t * mode,struct posix_acl ** default_acl,struct posix_acl ** acl)614 posix_acl_create(struct inode *dir, umode_t *mode,
615 struct posix_acl **default_acl, struct posix_acl **acl)
616 {
617 struct posix_acl *p;
618 struct posix_acl *clone;
619 int ret;
620
621 *acl = NULL;
622 *default_acl = NULL;
623
624 if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
625 return 0;
626
627 p = get_acl(dir, ACL_TYPE_DEFAULT);
628 if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
629 *mode &= ~current_umask();
630 return 0;
631 }
632 if (IS_ERR(p))
633 return PTR_ERR(p);
634
635 ret = -ENOMEM;
636 clone = posix_acl_clone(p, GFP_NOFS);
637 if (!clone)
638 goto err_release;
639
640 ret = posix_acl_create_masq(clone, mode);
641 if (ret < 0)
642 goto err_release_clone;
643
644 if (ret == 0)
645 posix_acl_release(clone);
646 else
647 *acl = clone;
648
649 if (!S_ISDIR(*mode))
650 posix_acl_release(p);
651 else
652 *default_acl = p;
653
654 return 0;
655
656 err_release_clone:
657 posix_acl_release(clone);
658 err_release:
659 posix_acl_release(p);
660 return ret;
661 }
662 EXPORT_SYMBOL_GPL(posix_acl_create);
663
664 /**
665 * posix_acl_update_mode - update mode in set_acl
666 * @mnt_userns: user namespace of the mount @inode was found from
667 * @inode: target inode
668 * @mode_p: mode (pointer) for update
669 * @acl: acl pointer
670 *
671 * Update the file mode when setting an ACL: compute the new file permission
672 * bits based on the ACL. In addition, if the ACL is equivalent to the new
673 * file mode, set *@acl to NULL to indicate that no ACL should be set.
674 *
675 * As with chmod, clear the setgid bit if the caller is not in the owning group
676 * or capable of CAP_FSETID (see inode_change_ok).
677 *
678 * If the inode has been found through an idmapped mount the user namespace of
679 * the vfsmount must be passed through @mnt_userns. This function will then
680 * take care to map the inode according to @mnt_userns before checking
681 * permissions. On non-idmapped mounts or if permission checking is to be
682 * performed on the raw inode simply passs init_user_ns.
683 *
684 * Called from set_acl inode operations.
685 */
posix_acl_update_mode(struct user_namespace * mnt_userns,struct inode * inode,umode_t * mode_p,struct posix_acl ** acl)686 int posix_acl_update_mode(struct user_namespace *mnt_userns,
687 struct inode *inode, umode_t *mode_p,
688 struct posix_acl **acl)
689 {
690 umode_t mode = inode->i_mode;
691 int error;
692
693 error = posix_acl_equiv_mode(*acl, &mode);
694 if (error < 0)
695 return error;
696 if (error == 0)
697 *acl = NULL;
698 if (!in_group_p(i_gid_into_mnt(mnt_userns, inode)) &&
699 !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
700 mode &= ~S_ISGID;
701 *mode_p = mode;
702 return 0;
703 }
704 EXPORT_SYMBOL(posix_acl_update_mode);
705
706 /*
707 * Fix up the uids and gids in posix acl extended attributes in place.
708 */
posix_acl_fix_xattr_userns(struct user_namespace * to,struct user_namespace * from,struct user_namespace * mnt_userns,void * value,size_t size,bool from_user)709 static void posix_acl_fix_xattr_userns(
710 struct user_namespace *to, struct user_namespace *from,
711 struct user_namespace *mnt_userns,
712 void *value, size_t size, bool from_user)
713 {
714 struct posix_acl_xattr_header *header = value;
715 struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
716 int count;
717 kuid_t uid;
718 kgid_t gid;
719
720 if (!value)
721 return;
722 if (size < sizeof(struct posix_acl_xattr_header))
723 return;
724 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
725 return;
726
727 count = posix_acl_xattr_count(size);
728 if (count < 0)
729 return;
730 if (count == 0)
731 return;
732
733 for (end = entry + count; entry != end; entry++) {
734 switch(le16_to_cpu(entry->e_tag)) {
735 case ACL_USER:
736 uid = make_kuid(from, le32_to_cpu(entry->e_id));
737 if (from_user)
738 uid = kuid_from_mnt(mnt_userns, uid);
739 else
740 uid = kuid_into_mnt(mnt_userns, uid);
741 entry->e_id = cpu_to_le32(from_kuid(to, uid));
742 break;
743 case ACL_GROUP:
744 gid = make_kgid(from, le32_to_cpu(entry->e_id));
745 if (from_user)
746 gid = kgid_from_mnt(mnt_userns, gid);
747 else
748 gid = kgid_into_mnt(mnt_userns, gid);
749 entry->e_id = cpu_to_le32(from_kgid(to, gid));
750 break;
751 default:
752 break;
753 }
754 }
755 }
756
posix_acl_fix_xattr_from_user(struct user_namespace * mnt_userns,void * value,size_t size)757 void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns,
758 void *value, size_t size)
759 {
760 struct user_namespace *user_ns = current_user_ns();
761 if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
762 return;
763 posix_acl_fix_xattr_userns(&init_user_ns, user_ns, mnt_userns, value,
764 size, true);
765 }
766
posix_acl_fix_xattr_to_user(struct user_namespace * mnt_userns,void * value,size_t size)767 void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns,
768 void *value, size_t size)
769 {
770 struct user_namespace *user_ns = current_user_ns();
771 if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
772 return;
773 posix_acl_fix_xattr_userns(user_ns, &init_user_ns, mnt_userns, value,
774 size, false);
775 }
776
777 /*
778 * Convert from extended attribute to in-memory representation.
779 */
780 struct posix_acl *
posix_acl_from_xattr(struct user_namespace * user_ns,const void * value,size_t size)781 posix_acl_from_xattr(struct user_namespace *user_ns,
782 const void *value, size_t size)
783 {
784 const struct posix_acl_xattr_header *header = value;
785 const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
786 int count;
787 struct posix_acl *acl;
788 struct posix_acl_entry *acl_e;
789
790 if (!value)
791 return NULL;
792 if (size < sizeof(struct posix_acl_xattr_header))
793 return ERR_PTR(-EINVAL);
794 if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
795 return ERR_PTR(-EOPNOTSUPP);
796
797 count = posix_acl_xattr_count(size);
798 if (count < 0)
799 return ERR_PTR(-EINVAL);
800 if (count == 0)
801 return NULL;
802
803 acl = posix_acl_alloc(count, GFP_NOFS);
804 if (!acl)
805 return ERR_PTR(-ENOMEM);
806 acl_e = acl->a_entries;
807
808 for (end = entry + count; entry != end; acl_e++, entry++) {
809 acl_e->e_tag = le16_to_cpu(entry->e_tag);
810 acl_e->e_perm = le16_to_cpu(entry->e_perm);
811
812 switch(acl_e->e_tag) {
813 case ACL_USER_OBJ:
814 case ACL_GROUP_OBJ:
815 case ACL_MASK:
816 case ACL_OTHER:
817 break;
818
819 case ACL_USER:
820 acl_e->e_uid =
821 make_kuid(user_ns,
822 le32_to_cpu(entry->e_id));
823 if (!uid_valid(acl_e->e_uid))
824 goto fail;
825 break;
826 case ACL_GROUP:
827 acl_e->e_gid =
828 make_kgid(user_ns,
829 le32_to_cpu(entry->e_id));
830 if (!gid_valid(acl_e->e_gid))
831 goto fail;
832 break;
833
834 default:
835 goto fail;
836 }
837 }
838 return acl;
839
840 fail:
841 posix_acl_release(acl);
842 return ERR_PTR(-EINVAL);
843 }
844 EXPORT_SYMBOL (posix_acl_from_xattr);
845
846 /*
847 * Convert from in-memory to extended attribute representation.
848 */
849 int
posix_acl_to_xattr(struct user_namespace * user_ns,const struct posix_acl * acl,void * buffer,size_t size)850 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
851 void *buffer, size_t size)
852 {
853 struct posix_acl_xattr_header *ext_acl = buffer;
854 struct posix_acl_xattr_entry *ext_entry;
855 int real_size, n;
856
857 real_size = posix_acl_xattr_size(acl->a_count);
858 if (!buffer)
859 return real_size;
860 if (real_size > size)
861 return -ERANGE;
862
863 ext_entry = (void *)(ext_acl + 1);
864 ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
865
866 for (n=0; n < acl->a_count; n++, ext_entry++) {
867 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
868 ext_entry->e_tag = cpu_to_le16(acl_e->e_tag);
869 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
870 switch(acl_e->e_tag) {
871 case ACL_USER:
872 ext_entry->e_id =
873 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
874 break;
875 case ACL_GROUP:
876 ext_entry->e_id =
877 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
878 break;
879 default:
880 ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
881 break;
882 }
883 }
884 return real_size;
885 }
886 EXPORT_SYMBOL (posix_acl_to_xattr);
887
888 static int
posix_acl_xattr_get(const struct xattr_handler * handler,struct dentry * unused,struct inode * inode,const char * name,void * value,size_t size)889 posix_acl_xattr_get(const struct xattr_handler *handler,
890 struct dentry *unused, struct inode *inode,
891 const char *name, void *value, size_t size)
892 {
893 struct posix_acl *acl;
894 int error;
895
896 if (!IS_POSIXACL(inode))
897 return -EOPNOTSUPP;
898 if (S_ISLNK(inode->i_mode))
899 return -EOPNOTSUPP;
900
901 acl = get_acl(inode, handler->flags);
902 if (IS_ERR(acl))
903 return PTR_ERR(acl);
904 if (acl == NULL)
905 return -ENODATA;
906
907 error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
908 posix_acl_release(acl);
909
910 return error;
911 }
912
913 int
set_posix_acl(struct user_namespace * mnt_userns,struct inode * inode,int type,struct posix_acl * acl)914 set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode,
915 int type, struct posix_acl *acl)
916 {
917 if (!IS_POSIXACL(inode))
918 return -EOPNOTSUPP;
919 if (!inode->i_op->set_acl)
920 return -EOPNOTSUPP;
921
922 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
923 return acl ? -EACCES : 0;
924 if (!inode_owner_or_capable(mnt_userns, inode))
925 return -EPERM;
926
927 if (acl) {
928 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
929 if (ret)
930 return ret;
931 }
932 return inode->i_op->set_acl(mnt_userns, inode, acl, type);
933 }
934 EXPORT_SYMBOL(set_posix_acl);
935
936 static int
posix_acl_xattr_set(const struct xattr_handler * handler,struct user_namespace * mnt_userns,struct dentry * unused,struct inode * inode,const char * name,const void * value,size_t size,int flags)937 posix_acl_xattr_set(const struct xattr_handler *handler,
938 struct user_namespace *mnt_userns,
939 struct dentry *unused, struct inode *inode,
940 const char *name, const void *value, size_t size,
941 int flags)
942 {
943 struct posix_acl *acl = NULL;
944 int ret;
945
946 if (value) {
947 acl = posix_acl_from_xattr(&init_user_ns, value, size);
948 if (IS_ERR(acl))
949 return PTR_ERR(acl);
950 }
951 ret = set_posix_acl(mnt_userns, inode, handler->flags, acl);
952 posix_acl_release(acl);
953 return ret;
954 }
955
956 static bool
posix_acl_xattr_list(struct dentry * dentry)957 posix_acl_xattr_list(struct dentry *dentry)
958 {
959 return IS_POSIXACL(d_backing_inode(dentry));
960 }
961
962 const struct xattr_handler posix_acl_access_xattr_handler = {
963 .name = XATTR_NAME_POSIX_ACL_ACCESS,
964 .flags = ACL_TYPE_ACCESS,
965 .list = posix_acl_xattr_list,
966 .get = posix_acl_xattr_get,
967 .set = posix_acl_xattr_set,
968 };
969 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
970
971 const struct xattr_handler posix_acl_default_xattr_handler = {
972 .name = XATTR_NAME_POSIX_ACL_DEFAULT,
973 .flags = ACL_TYPE_DEFAULT,
974 .list = posix_acl_xattr_list,
975 .get = posix_acl_xattr_get,
976 .set = posix_acl_xattr_set,
977 };
978 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
979
simple_set_acl(struct user_namespace * mnt_userns,struct inode * inode,struct posix_acl * acl,int type)980 int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
981 struct posix_acl *acl, int type)
982 {
983 int error;
984
985 if (type == ACL_TYPE_ACCESS) {
986 error = posix_acl_update_mode(mnt_userns, inode,
987 &inode->i_mode, &acl);
988 if (error)
989 return error;
990 }
991
992 inode->i_ctime = current_time(inode);
993 set_cached_acl(inode, type, acl);
994 return 0;
995 }
996
simple_acl_create(struct inode * dir,struct inode * inode)997 int simple_acl_create(struct inode *dir, struct inode *inode)
998 {
999 struct posix_acl *default_acl, *acl;
1000 int error;
1001
1002 error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
1003 if (error)
1004 return error;
1005
1006 set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
1007 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
1008
1009 if (default_acl)
1010 posix_acl_release(default_acl);
1011 if (acl)
1012 posix_acl_release(acl);
1013 return 0;
1014 }
1015
