GNU Linux-libre 5.19-rc6-gnu
[releases.git] / fs / posix_acl.c
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 #include <linux/mnt_idmapping.h>
27
28 static struct posix_acl **acl_by_type(struct inode *inode, int type)
29 {
30         switch (type) {
31         case ACL_TYPE_ACCESS:
32                 return &inode->i_acl;
33         case ACL_TYPE_DEFAULT:
34                 return &inode->i_default_acl;
35         default:
36                 BUG();
37         }
38 }
39
40 struct posix_acl *get_cached_acl(struct inode *inode, int type)
41 {
42         struct posix_acl **p = acl_by_type(inode, type);
43         struct posix_acl *acl;
44
45         for (;;) {
46                 rcu_read_lock();
47                 acl = rcu_dereference(*p);
48                 if (!acl || is_uncached_acl(acl) ||
49                     refcount_inc_not_zero(&acl->a_refcount))
50                         break;
51                 rcu_read_unlock();
52                 cpu_relax();
53         }
54         rcu_read_unlock();
55         return acl;
56 }
57 EXPORT_SYMBOL(get_cached_acl);
58
59 struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
60 {
61         struct posix_acl *acl = rcu_dereference(*acl_by_type(inode, type));
62
63         if (acl == ACL_DONT_CACHE) {
64                 struct posix_acl *ret;
65
66                 ret = inode->i_op->get_acl(inode, type, LOOKUP_RCU);
67                 if (!IS_ERR(ret))
68                         acl = ret;
69         }
70
71         return acl;
72 }
73 EXPORT_SYMBOL(get_cached_acl_rcu);
74
75 void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl)
76 {
77         struct posix_acl **p = acl_by_type(inode, type);
78         struct posix_acl *old;
79
80         old = xchg(p, posix_acl_dup(acl));
81         if (!is_uncached_acl(old))
82                 posix_acl_release(old);
83 }
84 EXPORT_SYMBOL(set_cached_acl);
85
86 static void __forget_cached_acl(struct posix_acl **p)
87 {
88         struct posix_acl *old;
89
90         old = xchg(p, ACL_NOT_CACHED);
91         if (!is_uncached_acl(old))
92                 posix_acl_release(old);
93 }
94
95 void forget_cached_acl(struct inode *inode, int type)
96 {
97         __forget_cached_acl(acl_by_type(inode, type));
98 }
99 EXPORT_SYMBOL(forget_cached_acl);
100
101 void forget_all_cached_acls(struct inode *inode)
102 {
103         __forget_cached_acl(&inode->i_acl);
104         __forget_cached_acl(&inode->i_default_acl);
105 }
106 EXPORT_SYMBOL(forget_all_cached_acls);
107
108 struct posix_acl *get_acl(struct inode *inode, int type)
109 {
110         void *sentinel;
111         struct posix_acl **p;
112         struct posix_acl *acl;
113
114         /*
115          * The sentinel is used to detect when another operation like
116          * set_cached_acl() or forget_cached_acl() races with get_acl().
117          * It is guaranteed that is_uncached_acl(sentinel) is true.
118          */
119
120         acl = get_cached_acl(inode, type);
121         if (!is_uncached_acl(acl))
122                 return acl;
123
124         if (!IS_POSIXACL(inode))
125                 return NULL;
126
127         sentinel = uncached_acl_sentinel(current);
128         p = acl_by_type(inode, type);
129
130         /*
131          * If the ACL isn't being read yet, set our sentinel.  Otherwise, the
132          * current value of the ACL will not be ACL_NOT_CACHED and so our own
133          * sentinel will not be set; another task will update the cache.  We
134          * could wait for that other task to complete its job, but it's easier
135          * to just call ->get_acl to fetch the ACL ourself.  (This is going to
136          * be an unlikely race.)
137          */
138         cmpxchg(p, ACL_NOT_CACHED, sentinel);
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
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 *
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 *
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
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
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 *
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
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 = mapped_kuid_fs(mnt_userns,
379                                                      i_user_ns(inode),
380                                                      pa->e_uid);
381                                 if (uid_eq(uid, current_fsuid()))
382                                         goto mask;
383                                 break;
384                         case ACL_GROUP_OBJ:
385                                 gid = i_gid_into_mnt(mnt_userns, inode);
386                                 if (in_group_p(gid)) {
387                                         found = 1;
388                                         if ((pa->e_perm & want) == want)
389                                                 goto mask;
390                                 }
391                                 break;
392                         case ACL_GROUP:
393                                 gid = mapped_kgid_fs(mnt_userns,
394                                                      i_user_ns(inode),
395                                                      pa->e_gid);
396                                 if (in_group_p(gid)) {
397                                         found = 1;
398                                         if ((pa->e_perm & want) == want)
399                                                 goto mask;
400                                 }
401                                 break;
402                         case ACL_MASK:
403                                 break;
404                         case ACL_OTHER:
405                                 if (found)
406                                         return -EACCES;
407                                 else
408                                         goto check_perm;
409                         default:
410                                 return -EIO;
411                 }
412         }
413         return -EIO;
414
415 mask:
416         for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
417                 if (mask_obj->e_tag == ACL_MASK) {
418                         if ((pa->e_perm & mask_obj->e_perm & want) == want)
419                                 return 0;
420                         return -EACCES;
421                 }
422         }
423
424 check_perm:
425         if ((pa->e_perm & want) == want)
426                 return 0;
427         return -EACCES;
428 }
429
430 /*
431  * Modify acl when creating a new inode. The caller must ensure the acl is
432  * only referenced once.
433  *
434  * mode_p initially must contain the mode parameter to the open() / creat()
435  * system calls. All permissions that are not granted by the acl are removed.
436  * The permissions in the acl are changed to reflect the mode_p parameter.
437  */
438 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
439 {
440         struct posix_acl_entry *pa, *pe;
441         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
442         umode_t mode = *mode_p;
443         int not_equiv = 0;
444
445         /* assert(atomic_read(acl->a_refcount) == 1); */
446
447         FOREACH_ACL_ENTRY(pa, acl, pe) {
448                 switch(pa->e_tag) {
449                         case ACL_USER_OBJ:
450                                 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
451                                 mode &= (pa->e_perm << 6) | ~S_IRWXU;
452                                 break;
453
454                         case ACL_USER:
455                         case ACL_GROUP:
456                                 not_equiv = 1;
457                                 break;
458
459                         case ACL_GROUP_OBJ:
460                                 group_obj = pa;
461                                 break;
462
463                         case ACL_OTHER:
464                                 pa->e_perm &= mode | ~S_IRWXO;
465                                 mode &= pa->e_perm | ~S_IRWXO;
466                                 break;
467
468                         case ACL_MASK:
469                                 mask_obj = pa;
470                                 not_equiv = 1;
471                                 break;
472
473                         default:
474                                 return -EIO;
475                 }
476         }
477
478         if (mask_obj) {
479                 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
480                 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
481         } else {
482                 if (!group_obj)
483                         return -EIO;
484                 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
485                 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
486         }
487
488         *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
489         return not_equiv;
490 }
491
492 /*
493  * Modify the ACL for the chmod syscall.
494  */
495 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
496 {
497         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
498         struct posix_acl_entry *pa, *pe;
499
500         /* assert(atomic_read(acl->a_refcount) == 1); */
501
502         FOREACH_ACL_ENTRY(pa, acl, pe) {
503                 switch(pa->e_tag) {
504                         case ACL_USER_OBJ:
505                                 pa->e_perm = (mode & S_IRWXU) >> 6;
506                                 break;
507
508                         case ACL_USER:
509                         case ACL_GROUP:
510                                 break;
511
512                         case ACL_GROUP_OBJ:
513                                 group_obj = pa;
514                                 break;
515
516                         case ACL_MASK:
517                                 mask_obj = pa;
518                                 break;
519
520                         case ACL_OTHER:
521                                 pa->e_perm = (mode & S_IRWXO);
522                                 break;
523
524                         default:
525                                 return -EIO;
526                 }
527         }
528
529         if (mask_obj) {
530                 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
531         } else {
532                 if (!group_obj)
533                         return -EIO;
534                 group_obj->e_perm = (mode & S_IRWXG) >> 3;
535         }
536
537         return 0;
538 }
539
540 int
541 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
542 {
543         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
544         int err = -ENOMEM;
545         if (clone) {
546                 err = posix_acl_create_masq(clone, mode_p);
547                 if (err < 0) {
548                         posix_acl_release(clone);
549                         clone = NULL;
550                 }
551         }
552         posix_acl_release(*acl);
553         *acl = clone;
554         return err;
555 }
556 EXPORT_SYMBOL(__posix_acl_create);
557
558 int
559 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
560 {
561         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
562         int err = -ENOMEM;
563         if (clone) {
564                 err = __posix_acl_chmod_masq(clone, mode);
565                 if (err) {
566                         posix_acl_release(clone);
567                         clone = NULL;
568                 }
569         }
570         posix_acl_release(*acl);
571         *acl = clone;
572         return err;
573 }
574 EXPORT_SYMBOL(__posix_acl_chmod);
575
576 /**
577  * posix_acl_chmod - chmod a posix acl
578  *
579  * @mnt_userns: user namespace of the mount @inode was found from
580  * @inode:      inode to check permissions on
581  * @mode:       the new mode of @inode
582  *
583  * If the inode has been found through an idmapped mount the user namespace of
584  * the vfsmount must be passed through @mnt_userns. This function will then
585  * take care to map the inode according to @mnt_userns before checking
586  * permissions. On non-idmapped mounts or if permission checking is to be
587  * performed on the raw inode simply passs init_user_ns.
588  */
589 int
590  posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode,
591                     umode_t mode)
592 {
593         struct posix_acl *acl;
594         int ret = 0;
595
596         if (!IS_POSIXACL(inode))
597                 return 0;
598         if (!inode->i_op->set_acl)
599                 return -EOPNOTSUPP;
600
601         acl = get_acl(inode, ACL_TYPE_ACCESS);
602         if (IS_ERR_OR_NULL(acl)) {
603                 if (acl == ERR_PTR(-EOPNOTSUPP))
604                         return 0;
605                 return PTR_ERR(acl);
606         }
607
608         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
609         if (ret)
610                 return ret;
611         ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS);
612         posix_acl_release(acl);
613         return ret;
614 }
615 EXPORT_SYMBOL(posix_acl_chmod);
616
617 int
618 posix_acl_create(struct inode *dir, umode_t *mode,
619                 struct posix_acl **default_acl, struct posix_acl **acl)
620 {
621         struct posix_acl *p;
622         struct posix_acl *clone;
623         int ret;
624
625         *acl = NULL;
626         *default_acl = NULL;
627
628         if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
629                 return 0;
630
631         p = get_acl(dir, ACL_TYPE_DEFAULT);
632         if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
633                 *mode &= ~current_umask();
634                 return 0;
635         }
636         if (IS_ERR(p))
637                 return PTR_ERR(p);
638
639         ret = -ENOMEM;
640         clone = posix_acl_clone(p, GFP_NOFS);
641         if (!clone)
642                 goto err_release;
643
644         ret = posix_acl_create_masq(clone, mode);
645         if (ret < 0)
646                 goto err_release_clone;
647
648         if (ret == 0)
649                 posix_acl_release(clone);
650         else
651                 *acl = clone;
652
653         if (!S_ISDIR(*mode))
654                 posix_acl_release(p);
655         else
656                 *default_acl = p;
657
658         return 0;
659
660 err_release_clone:
661         posix_acl_release(clone);
662 err_release:
663         posix_acl_release(p);
664         return ret;
665 }
666 EXPORT_SYMBOL_GPL(posix_acl_create);
667
668 /**
669  * posix_acl_update_mode  -  update mode in set_acl
670  * @mnt_userns: user namespace of the mount @inode was found from
671  * @inode:      target inode
672  * @mode_p:     mode (pointer) for update
673  * @acl:        acl pointer
674  *
675  * Update the file mode when setting an ACL: compute the new file permission
676  * bits based on the ACL.  In addition, if the ACL is equivalent to the new
677  * file mode, set *@acl to NULL to indicate that no ACL should be set.
678  *
679  * As with chmod, clear the setgid bit if the caller is not in the owning group
680  * or capable of CAP_FSETID (see inode_change_ok).
681  *
682  * If the inode has been found through an idmapped mount the user namespace of
683  * the vfsmount must be passed through @mnt_userns. This function will then
684  * take care to map the inode according to @mnt_userns before checking
685  * permissions. On non-idmapped mounts or if permission checking is to be
686  * performed on the raw inode simply passs init_user_ns.
687  *
688  * Called from set_acl inode operations.
689  */
690 int posix_acl_update_mode(struct user_namespace *mnt_userns,
691                           struct inode *inode, umode_t *mode_p,
692                           struct posix_acl **acl)
693 {
694         umode_t mode = inode->i_mode;
695         int error;
696
697         error = posix_acl_equiv_mode(*acl, &mode);
698         if (error < 0)
699                 return error;
700         if (error == 0)
701                 *acl = NULL;
702         if (!in_group_p(i_gid_into_mnt(mnt_userns, inode)) &&
703             !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
704                 mode &= ~S_ISGID;
705         *mode_p = mode;
706         return 0;
707 }
708 EXPORT_SYMBOL(posix_acl_update_mode);
709
710 /*
711  * Fix up the uids and gids in posix acl extended attributes in place.
712  */
713 static void posix_acl_fix_xattr_userns(
714         struct user_namespace *to, struct user_namespace *from,
715         struct user_namespace *mnt_userns,
716         void *value, size_t size, bool from_user)
717 {
718         struct posix_acl_xattr_header *header = value;
719         struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
720         int count;
721         kuid_t uid;
722         kgid_t gid;
723
724         if (!value)
725                 return;
726         if (size < sizeof(struct posix_acl_xattr_header))
727                 return;
728         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
729                 return;
730
731         count = posix_acl_xattr_count(size);
732         if (count < 0)
733                 return;
734         if (count == 0)
735                 return;
736
737         for (end = entry + count; entry != end; entry++) {
738                 switch(le16_to_cpu(entry->e_tag)) {
739                 case ACL_USER:
740                         uid = make_kuid(from, le32_to_cpu(entry->e_id));
741                         if (from_user)
742                                 uid = mapped_kuid_user(mnt_userns, &init_user_ns, uid);
743                         else
744                                 uid = mapped_kuid_fs(mnt_userns, &init_user_ns, uid);
745                         entry->e_id = cpu_to_le32(from_kuid(to, uid));
746                         break;
747                 case ACL_GROUP:
748                         gid = make_kgid(from, le32_to_cpu(entry->e_id));
749                         if (from_user)
750                                 gid = mapped_kgid_user(mnt_userns, &init_user_ns, gid);
751                         else
752                                 gid = mapped_kgid_fs(mnt_userns, &init_user_ns, gid);
753                         entry->e_id = cpu_to_le32(from_kgid(to, gid));
754                         break;
755                 default:
756                         break;
757                 }
758         }
759 }
760
761 void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns,
762                                    struct inode *inode,
763                                    void *value, size_t size)
764 {
765         struct user_namespace *user_ns = current_user_ns();
766
767         /* Leave ids untouched on non-idmapped mounts. */
768         if (no_idmapping(mnt_userns, i_user_ns(inode)))
769                 mnt_userns = &init_user_ns;
770         if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
771                 return;
772         posix_acl_fix_xattr_userns(&init_user_ns, user_ns, mnt_userns, value,
773                                    size, true);
774 }
775
776 void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns,
777                                  struct inode *inode,
778                                  void *value, size_t size)
779 {
780         struct user_namespace *user_ns = current_user_ns();
781
782         /* Leave ids untouched on non-idmapped mounts. */
783         if (no_idmapping(mnt_userns, i_user_ns(inode)))
784                 mnt_userns = &init_user_ns;
785         if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
786                 return;
787         posix_acl_fix_xattr_userns(user_ns, &init_user_ns, mnt_userns, value,
788                                    size, false);
789 }
790
791 /*
792  * Convert from extended attribute to in-memory representation.
793  */
794 struct posix_acl *
795 posix_acl_from_xattr(struct user_namespace *user_ns,
796                      const void *value, size_t size)
797 {
798         const struct posix_acl_xattr_header *header = value;
799         const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
800         int count;
801         struct posix_acl *acl;
802         struct posix_acl_entry *acl_e;
803
804         if (!value)
805                 return NULL;
806         if (size < sizeof(struct posix_acl_xattr_header))
807                  return ERR_PTR(-EINVAL);
808         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
809                 return ERR_PTR(-EOPNOTSUPP);
810
811         count = posix_acl_xattr_count(size);
812         if (count < 0)
813                 return ERR_PTR(-EINVAL);
814         if (count == 0)
815                 return NULL;
816         
817         acl = posix_acl_alloc(count, GFP_NOFS);
818         if (!acl)
819                 return ERR_PTR(-ENOMEM);
820         acl_e = acl->a_entries;
821         
822         for (end = entry + count; entry != end; acl_e++, entry++) {
823                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
824                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
825
826                 switch(acl_e->e_tag) {
827                         case ACL_USER_OBJ:
828                         case ACL_GROUP_OBJ:
829                         case ACL_MASK:
830                         case ACL_OTHER:
831                                 break;
832
833                         case ACL_USER:
834                                 acl_e->e_uid =
835                                         make_kuid(user_ns,
836                                                   le32_to_cpu(entry->e_id));
837                                 if (!uid_valid(acl_e->e_uid))
838                                         goto fail;
839                                 break;
840                         case ACL_GROUP:
841                                 acl_e->e_gid =
842                                         make_kgid(user_ns,
843                                                   le32_to_cpu(entry->e_id));
844                                 if (!gid_valid(acl_e->e_gid))
845                                         goto fail;
846                                 break;
847
848                         default:
849                                 goto fail;
850                 }
851         }
852         return acl;
853
854 fail:
855         posix_acl_release(acl);
856         return ERR_PTR(-EINVAL);
857 }
858 EXPORT_SYMBOL (posix_acl_from_xattr);
859
860 /*
861  * Convert from in-memory to extended attribute representation.
862  */
863 int
864 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
865                    void *buffer, size_t size)
866 {
867         struct posix_acl_xattr_header *ext_acl = buffer;
868         struct posix_acl_xattr_entry *ext_entry;
869         int real_size, n;
870
871         real_size = posix_acl_xattr_size(acl->a_count);
872         if (!buffer)
873                 return real_size;
874         if (real_size > size)
875                 return -ERANGE;
876
877         ext_entry = (void *)(ext_acl + 1);
878         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
879
880         for (n=0; n < acl->a_count; n++, ext_entry++) {
881                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
882                 ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
883                 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
884                 switch(acl_e->e_tag) {
885                 case ACL_USER:
886                         ext_entry->e_id =
887                                 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
888                         break;
889                 case ACL_GROUP:
890                         ext_entry->e_id =
891                                 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
892                         break;
893                 default:
894                         ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
895                         break;
896                 }
897         }
898         return real_size;
899 }
900 EXPORT_SYMBOL (posix_acl_to_xattr);
901
902 static int
903 posix_acl_xattr_get(const struct xattr_handler *handler,
904                     struct dentry *unused, struct inode *inode,
905                     const char *name, void *value, size_t size)
906 {
907         struct posix_acl *acl;
908         int error;
909
910         if (!IS_POSIXACL(inode))
911                 return -EOPNOTSUPP;
912         if (S_ISLNK(inode->i_mode))
913                 return -EOPNOTSUPP;
914
915         acl = get_acl(inode, handler->flags);
916         if (IS_ERR(acl))
917                 return PTR_ERR(acl);
918         if (acl == NULL)
919                 return -ENODATA;
920
921         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
922         posix_acl_release(acl);
923
924         return error;
925 }
926
927 int
928 set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode,
929               int type, struct posix_acl *acl)
930 {
931         if (!IS_POSIXACL(inode))
932                 return -EOPNOTSUPP;
933         if (!inode->i_op->set_acl)
934                 return -EOPNOTSUPP;
935
936         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
937                 return acl ? -EACCES : 0;
938         if (!inode_owner_or_capable(mnt_userns, inode))
939                 return -EPERM;
940
941         if (acl) {
942                 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
943                 if (ret)
944                         return ret;
945         }
946         return inode->i_op->set_acl(mnt_userns, inode, acl, type);
947 }
948 EXPORT_SYMBOL(set_posix_acl);
949
950 static int
951 posix_acl_xattr_set(const struct xattr_handler *handler,
952                            struct user_namespace *mnt_userns,
953                            struct dentry *unused, struct inode *inode,
954                            const char *name, const void *value, size_t size,
955                            int flags)
956 {
957         struct posix_acl *acl = NULL;
958         int ret;
959
960         if (value) {
961                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
962                 if (IS_ERR(acl))
963                         return PTR_ERR(acl);
964         }
965         ret = set_posix_acl(mnt_userns, inode, handler->flags, acl);
966         posix_acl_release(acl);
967         return ret;
968 }
969
970 static bool
971 posix_acl_xattr_list(struct dentry *dentry)
972 {
973         return IS_POSIXACL(d_backing_inode(dentry));
974 }
975
976 const struct xattr_handler posix_acl_access_xattr_handler = {
977         .name = XATTR_NAME_POSIX_ACL_ACCESS,
978         .flags = ACL_TYPE_ACCESS,
979         .list = posix_acl_xattr_list,
980         .get = posix_acl_xattr_get,
981         .set = posix_acl_xattr_set,
982 };
983 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
984
985 const struct xattr_handler posix_acl_default_xattr_handler = {
986         .name = XATTR_NAME_POSIX_ACL_DEFAULT,
987         .flags = ACL_TYPE_DEFAULT,
988         .list = posix_acl_xattr_list,
989         .get = posix_acl_xattr_get,
990         .set = posix_acl_xattr_set,
991 };
992 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
993
994 int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
995                    struct posix_acl *acl, int type)
996 {
997         int error;
998
999         if (type == ACL_TYPE_ACCESS) {
1000                 error = posix_acl_update_mode(mnt_userns, inode,
1001                                 &inode->i_mode, &acl);
1002                 if (error)
1003                         return error;
1004         }
1005
1006         inode->i_ctime = current_time(inode);
1007         set_cached_acl(inode, type, acl);
1008         return 0;
1009 }
1010
1011 int simple_acl_create(struct inode *dir, struct inode *inode)
1012 {
1013         struct posix_acl *default_acl, *acl;
1014         int error;
1015
1016         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
1017         if (error)
1018                 return error;
1019
1020         set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
1021         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
1022
1023         if (default_acl)
1024                 posix_acl_release(default_acl);
1025         if (acl)
1026                 posix_acl_release(acl);
1027         return 0;
1028 }