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