blob: c9d48dc784953fa4af62f9af58dfbb56ed2faa70
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 | |
24 | static 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 | |
36 | struct 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 | } |
53 | EXPORT_SYMBOL(get_cached_acl); |
54 | |
55 | struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type) |
56 | { |
57 | return rcu_dereference(*acl_by_type(inode, type)); |
58 | } |
59 | EXPORT_SYMBOL(get_cached_acl_rcu); |
60 | |
61 | void 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 | } |
70 | EXPORT_SYMBOL(set_cached_acl); |
71 | |
72 | static 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 | |
81 | void forget_cached_acl(struct inode *inode, int type) |
82 | { |
83 | __forget_cached_acl(acl_by_type(inode, type)); |
84 | } |
85 | EXPORT_SYMBOL(forget_cached_acl); |
86 | |
87 | void forget_all_cached_acls(struct inode *inode) |
88 | { |
89 | __forget_cached_acl(&inode->i_acl); |
90 | __forget_cached_acl(&inode->i_default_acl); |
91 | } |
92 | EXPORT_SYMBOL(forget_all_cached_acls); |
93 | |
94 | struct 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 | } |
158 | EXPORT_SYMBOL(get_acl); |
159 | |
160 | /* |
161 | * Init a fresh posix_acl |
162 | */ |
163 | void |
164 | posix_acl_init(struct posix_acl *acl, int count) |
165 | { |
166 | atomic_set(&acl->a_refcount, 1); |
167 | acl->a_count = count; |
168 | } |
169 | EXPORT_SYMBOL(posix_acl_init); |
170 | |
171 | /* |
172 | * Allocate a new ACL with the specified number of entries. |
173 | */ |
174 | struct posix_acl * |
175 | posix_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 | } |
184 | EXPORT_SYMBOL(posix_acl_alloc); |
185 | |
186 | /* |
187 | * Clone an ACL. |
188 | */ |
189 | static struct posix_acl * |
190 | posix_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 | */ |
207 | int |
208 | posix_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 | } |
270 | EXPORT_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 | */ |
276 | int |
277 | posix_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 | } |
317 | EXPORT_SYMBOL(posix_acl_equiv_mode); |
318 | |
319 | /* |
320 | * Create an ACL representing the file mode permission bits of an inode. |
321 | */ |
322 | struct posix_acl * |
323 | posix_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 | } |
339 | EXPORT_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 | */ |
345 | int |
346 | posix_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 | |
391 | mask: |
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 | |
400 | check_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 | */ |
414 | static 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 | */ |
471 | static 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 | |
516 | int |
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 | } |
532 | EXPORT_SYMBOL(__posix_acl_create); |
533 | |
534 | int |
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 | } |
550 | EXPORT_SYMBOL(__posix_acl_chmod); |
551 | |
552 | int |
553 | posix_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 | } |
577 | EXPORT_SYMBOL(posix_acl_chmod); |
578 | |
579 | int |
580 | posix_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 | |
622 | err_release_clone: |
623 | posix_acl_release(clone); |
624 | err_release: |
625 | posix_acl_release(p); |
626 | return ret; |
627 | } |
628 | EXPORT_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 | */ |
642 | int 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 | } |
659 | EXPORT_SYMBOL(posix_acl_update_mode); |
660 | |
661 | /* |
662 | * Fix up the uids and gids in posix acl extended attributes in place. |
663 | */ |
664 | static 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 | |
703 | void 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 | |
711 | void 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 | */ |
722 | struct posix_acl * |
723 | posix_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 | |
782 | fail: |
783 | posix_acl_release(acl); |
784 | return ERR_PTR(-EINVAL); |
785 | } |
786 | EXPORT_SYMBOL (posix_acl_from_xattr); |
787 | |
788 | /* |
789 | * Convert from in-memory to extended attribute representation. |
790 | */ |
791 | int |
792 | posix_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 | } |
828 | EXPORT_SYMBOL (posix_acl_to_xattr); |
829 | |
830 | static int |
831 | posix_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 | |
855 | int |
856 | set_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 | } |
875 | EXPORT_SYMBOL(set_posix_acl); |
876 | |
877 | static int |
878 | posix_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 | |
896 | static bool |
897 | posix_acl_xattr_list(struct dentry *dentry) |
898 | { |
899 | return IS_POSIXACL(d_backing_inode(dentry)); |
900 | } |
901 | |
902 | const 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 | }; |
909 | EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler); |
910 | |
911 | const 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 | }; |
918 | EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler); |
919 | |
920 | int 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 | |
936 | int 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 | } |
954 |