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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 | ||
26 | static 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 | ||
38 | struct 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 | } | |
55 | EXPORT_SYMBOL(get_cached_acl); | |
56 | ||
57 | struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type) | |
58 | { | |
59 | return rcu_dereference(*acl_by_type(inode, type)); | |
60 | } | |
61 | EXPORT_SYMBOL(get_cached_acl_rcu); | |
62 | ||
63 | void 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 | } | |
72 | EXPORT_SYMBOL(set_cached_acl); | |
73 | ||
74 | static 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 | ||
83 | void forget_cached_acl(struct inode *inode, int type) | |
84 | { | |
85 | __forget_cached_acl(acl_by_type(inode, type)); | |
86 | } | |
87 | EXPORT_SYMBOL(forget_cached_acl); | |
88 | ||
89 | void forget_all_cached_acls(struct inode *inode) | |
90 | { | |
91 | __forget_cached_acl(&inode->i_acl); | |
92 | __forget_cached_acl(&inode->i_default_acl); | |
93 | } | |
94 | EXPORT_SYMBOL(forget_all_cached_acls); | |
95 | ||
96 | struct 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 | } | |
160 | EXPORT_SYMBOL(get_acl); | |
161 | ||
162 | /* | |
163 | * Init a fresh posix_acl | |
164 | */ | |
165 | void | |
166 | posix_acl_init(struct posix_acl *acl, int count) | |
167 | { | |
168 | refcount_set(&acl->a_refcount, 1); | |
169 | acl->a_count = count; | |
170 | } | |
171 | EXPORT_SYMBOL(posix_acl_init); | |
172 | ||
173 | /* | |
174 | * Allocate a new ACL with the specified number of entries. | |
175 | */ | |
176 | struct posix_acl * | |
177 | posix_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 | } | |
186 | EXPORT_SYMBOL(posix_acl_alloc); | |
187 | ||
188 | /* | |
189 | * Clone an ACL. | |
190 | */ | |
191 | static struct posix_acl * | |
192 | posix_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 | */ | |
209 | int | |
210 | posix_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 | } | |
272 | EXPORT_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 | */ | |
278 | int | |
279 | posix_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 | } | |
319 | EXPORT_SYMBOL(posix_acl_equiv_mode); | |
320 | ||
321 | /* | |
322 | * Create an ACL representing the file mode permission bits of an inode. | |
323 | */ | |
324 | struct posix_acl * | |
325 | posix_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 | } | |
341 | EXPORT_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 | */ | |
347 | int | |
348 | posix_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 | ||
393 | mask: | |
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 | ||
402 | check_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 | */ | |
416 | static 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 | */ | |
473 | static 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 | ||
518 | int | |
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 | } | |
534 | EXPORT_SYMBOL(__posix_acl_create); | |
535 | ||
536 | int | |
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 | } | |
552 | EXPORT_SYMBOL(__posix_acl_chmod); | |
553 | ||
554 | int | |
555 | posix_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 | } | |
579 | EXPORT_SYMBOL(posix_acl_chmod); | |
580 | ||
581 | int | |
582 | posix_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 | ||
624 | err_release_clone: | |
625 | posix_acl_release(clone); | |
626 | err_release: | |
627 | posix_acl_release(p); | |
628 | return ret; | |
629 | } | |
630 | EXPORT_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 | */ | |
644 | int 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 | } | |
661 | EXPORT_SYMBOL(posix_acl_update_mode); | |
662 | ||
663 | /* | |
664 | * Fix up the uids and gids in posix acl extended attributes in place. | |
665 | */ | |
666 | static 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 | ||
705 | void 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 | ||
713 | void 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 | */ | |
724 | struct posix_acl * | |
725 | posix_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 | ||
784 | fail: | |
785 | posix_acl_release(acl); | |
786 | return ERR_PTR(-EINVAL); | |
787 | } | |
788 | EXPORT_SYMBOL (posix_acl_from_xattr); | |
789 | ||
790 | /* | |
791 | * Convert from in-memory to extended attribute representation. | |
792 | */ | |
793 | int | |
794 | posix_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 | } | |
830 | EXPORT_SYMBOL (posix_acl_to_xattr); | |
831 | ||
832 | static int | |
833 | posix_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 | ||
857 | int | |
858 | set_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 | } | |
877 | EXPORT_SYMBOL(set_posix_acl); | |
878 | ||
879 | static int | |
880 | posix_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 | ||
898 | static bool | |
899 | posix_acl_xattr_list(struct dentry *dentry) | |
900 | { | |
901 | return IS_POSIXACL(d_backing_inode(dentry)); | |
902 | } | |
903 | ||
904 | const 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 | }; | |
911 | EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler); | |
912 | ||
913 | const 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 | }; | |
920 | EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler); | |
921 | ||
922 | int 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 | ||
938 | int 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 | } |