scsi: target: core: Get rid of warning in compare_and_write_do_cmp()
[linux-2.6-microblaze.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
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 user_namespace *mnt_userns, struct inode *inode,
349                      const struct posix_acl *acl, int want)
350 {
351         const struct posix_acl_entry *pa, *pe, *mask_obj;
352         int found = 0;
353         kuid_t uid;
354         kgid_t gid;
355
356         want &= MAY_READ | MAY_WRITE | MAY_EXEC;
357
358         FOREACH_ACL_ENTRY(pa, acl, pe) {
359                 switch(pa->e_tag) {
360                         case ACL_USER_OBJ:
361                                 /* (May have been checked already) */
362                                 uid = i_uid_into_mnt(mnt_userns, inode);
363                                 if (uid_eq(uid, current_fsuid()))
364                                         goto check_perm;
365                                 break;
366                         case ACL_USER:
367                                 uid = kuid_into_mnt(mnt_userns, pa->e_uid);
368                                 if (uid_eq(uid, current_fsuid()))
369                                         goto mask;
370                                 break;
371                         case ACL_GROUP_OBJ:
372                                 gid = i_gid_into_mnt(mnt_userns, inode);
373                                 if (in_group_p(gid)) {
374                                         found = 1;
375                                         if ((pa->e_perm & want) == want)
376                                                 goto mask;
377                                 }
378                                 break;
379                         case ACL_GROUP:
380                                 gid = kgid_into_mnt(mnt_userns, pa->e_gid);
381                                 if (in_group_p(gid)) {
382                                         found = 1;
383                                         if ((pa->e_perm & want) == want)
384                                                 goto mask;
385                                 }
386                                 break;
387                         case ACL_MASK:
388                                 break;
389                         case ACL_OTHER:
390                                 if (found)
391                                         return -EACCES;
392                                 else
393                                         goto check_perm;
394                         default:
395                                 return -EIO;
396                 }
397         }
398         return -EIO;
399
400 mask:
401         for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
402                 if (mask_obj->e_tag == ACL_MASK) {
403                         if ((pa->e_perm & mask_obj->e_perm & want) == want)
404                                 return 0;
405                         return -EACCES;
406                 }
407         }
408
409 check_perm:
410         if ((pa->e_perm & want) == want)
411                 return 0;
412         return -EACCES;
413 }
414
415 /*
416  * Modify acl when creating a new inode. The caller must ensure the acl is
417  * only referenced once.
418  *
419  * mode_p initially must contain the mode parameter to the open() / creat()
420  * system calls. All permissions that are not granted by the acl are removed.
421  * The permissions in the acl are changed to reflect the mode_p parameter.
422  */
423 static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
424 {
425         struct posix_acl_entry *pa, *pe;
426         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
427         umode_t mode = *mode_p;
428         int not_equiv = 0;
429
430         /* assert(atomic_read(acl->a_refcount) == 1); */
431
432         FOREACH_ACL_ENTRY(pa, acl, pe) {
433                 switch(pa->e_tag) {
434                         case ACL_USER_OBJ:
435                                 pa->e_perm &= (mode >> 6) | ~S_IRWXO;
436                                 mode &= (pa->e_perm << 6) | ~S_IRWXU;
437                                 break;
438
439                         case ACL_USER:
440                         case ACL_GROUP:
441                                 not_equiv = 1;
442                                 break;
443
444                         case ACL_GROUP_OBJ:
445                                 group_obj = pa;
446                                 break;
447
448                         case ACL_OTHER:
449                                 pa->e_perm &= mode | ~S_IRWXO;
450                                 mode &= pa->e_perm | ~S_IRWXO;
451                                 break;
452
453                         case ACL_MASK:
454                                 mask_obj = pa;
455                                 not_equiv = 1;
456                                 break;
457
458                         default:
459                                 return -EIO;
460                 }
461         }
462
463         if (mask_obj) {
464                 mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
465                 mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
466         } else {
467                 if (!group_obj)
468                         return -EIO;
469                 group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
470                 mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
471         }
472
473         *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
474         return not_equiv;
475 }
476
477 /*
478  * Modify the ACL for the chmod syscall.
479  */
480 static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
481 {
482         struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
483         struct posix_acl_entry *pa, *pe;
484
485         /* assert(atomic_read(acl->a_refcount) == 1); */
486
487         FOREACH_ACL_ENTRY(pa, acl, pe) {
488                 switch(pa->e_tag) {
489                         case ACL_USER_OBJ:
490                                 pa->e_perm = (mode & S_IRWXU) >> 6;
491                                 break;
492
493                         case ACL_USER:
494                         case ACL_GROUP:
495                                 break;
496
497                         case ACL_GROUP_OBJ:
498                                 group_obj = pa;
499                                 break;
500
501                         case ACL_MASK:
502                                 mask_obj = pa;
503                                 break;
504
505                         case ACL_OTHER:
506                                 pa->e_perm = (mode & S_IRWXO);
507                                 break;
508
509                         default:
510                                 return -EIO;
511                 }
512         }
513
514         if (mask_obj) {
515                 mask_obj->e_perm = (mode & S_IRWXG) >> 3;
516         } else {
517                 if (!group_obj)
518                         return -EIO;
519                 group_obj->e_perm = (mode & S_IRWXG) >> 3;
520         }
521
522         return 0;
523 }
524
525 int
526 __posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
527 {
528         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
529         int err = -ENOMEM;
530         if (clone) {
531                 err = posix_acl_create_masq(clone, mode_p);
532                 if (err < 0) {
533                         posix_acl_release(clone);
534                         clone = NULL;
535                 }
536         }
537         posix_acl_release(*acl);
538         *acl = clone;
539         return err;
540 }
541 EXPORT_SYMBOL(__posix_acl_create);
542
543 int
544 __posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
545 {
546         struct posix_acl *clone = posix_acl_clone(*acl, gfp);
547         int err = -ENOMEM;
548         if (clone) {
549                 err = __posix_acl_chmod_masq(clone, mode);
550                 if (err) {
551                         posix_acl_release(clone);
552                         clone = NULL;
553                 }
554         }
555         posix_acl_release(*acl);
556         *acl = clone;
557         return err;
558 }
559 EXPORT_SYMBOL(__posix_acl_chmod);
560
561 /**
562  * posix_acl_chmod - chmod a posix acl
563  *
564  * @mnt_userns: user namespace of the mount @inode was found from
565  * @inode:      inode to check permissions on
566  * @mode:       the new mode of @inode
567  *
568  * If the inode has been found through an idmapped mount the user namespace of
569  * the vfsmount must be passed through @mnt_userns. This function will then
570  * take care to map the inode according to @mnt_userns before checking
571  * permissions. On non-idmapped mounts or if permission checking is to be
572  * performed on the raw inode simply passs init_user_ns.
573  */
574 int
575  posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode,
576                     umode_t mode)
577 {
578         struct posix_acl *acl;
579         int ret = 0;
580
581         if (!IS_POSIXACL(inode))
582                 return 0;
583         if (!inode->i_op->set_acl)
584                 return -EOPNOTSUPP;
585
586         acl = get_acl(inode, ACL_TYPE_ACCESS);
587         if (IS_ERR_OR_NULL(acl)) {
588                 if (acl == ERR_PTR(-EOPNOTSUPP))
589                         return 0;
590                 return PTR_ERR(acl);
591         }
592
593         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
594         if (ret)
595                 return ret;
596         ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS);
597         posix_acl_release(acl);
598         return ret;
599 }
600 EXPORT_SYMBOL(posix_acl_chmod);
601
602 int
603 posix_acl_create(struct inode *dir, umode_t *mode,
604                 struct posix_acl **default_acl, struct posix_acl **acl)
605 {
606         struct posix_acl *p;
607         struct posix_acl *clone;
608         int ret;
609
610         *acl = NULL;
611         *default_acl = NULL;
612
613         if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
614                 return 0;
615
616         p = get_acl(dir, ACL_TYPE_DEFAULT);
617         if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
618                 *mode &= ~current_umask();
619                 return 0;
620         }
621         if (IS_ERR(p))
622                 return PTR_ERR(p);
623
624         ret = -ENOMEM;
625         clone = posix_acl_clone(p, GFP_NOFS);
626         if (!clone)
627                 goto err_release;
628
629         ret = posix_acl_create_masq(clone, mode);
630         if (ret < 0)
631                 goto err_release_clone;
632
633         if (ret == 0)
634                 posix_acl_release(clone);
635         else
636                 *acl = clone;
637
638         if (!S_ISDIR(*mode))
639                 posix_acl_release(p);
640         else
641                 *default_acl = p;
642
643         return 0;
644
645 err_release_clone:
646         posix_acl_release(clone);
647 err_release:
648         posix_acl_release(p);
649         return ret;
650 }
651 EXPORT_SYMBOL_GPL(posix_acl_create);
652
653 /**
654  * posix_acl_update_mode  -  update mode in set_acl
655  * @mnt_userns: user namespace of the mount @inode was found from
656  * @inode:      target inode
657  * @mode_p:     mode (pointer) for update
658  * @acl:        acl pointer
659  *
660  * Update the file mode when setting an ACL: compute the new file permission
661  * bits based on the ACL.  In addition, if the ACL is equivalent to the new
662  * file mode, set *@acl to NULL to indicate that no ACL should be set.
663  *
664  * As with chmod, clear the setgid bit if the caller is not in the owning group
665  * or capable of CAP_FSETID (see inode_change_ok).
666  *
667  * If the inode has been found through an idmapped mount the user namespace of
668  * the vfsmount must be passed through @mnt_userns. This function will then
669  * take care to map the inode according to @mnt_userns before checking
670  * permissions. On non-idmapped mounts or if permission checking is to be
671  * performed on the raw inode simply passs init_user_ns.
672  *
673  * Called from set_acl inode operations.
674  */
675 int posix_acl_update_mode(struct user_namespace *mnt_userns,
676                           struct inode *inode, umode_t *mode_p,
677                           struct posix_acl **acl)
678 {
679         umode_t mode = inode->i_mode;
680         int error;
681
682         error = posix_acl_equiv_mode(*acl, &mode);
683         if (error < 0)
684                 return error;
685         if (error == 0)
686                 *acl = NULL;
687         if (!in_group_p(i_gid_into_mnt(mnt_userns, inode)) &&
688             !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
689                 mode &= ~S_ISGID;
690         *mode_p = mode;
691         return 0;
692 }
693 EXPORT_SYMBOL(posix_acl_update_mode);
694
695 /*
696  * Fix up the uids and gids in posix acl extended attributes in place.
697  */
698 static void posix_acl_fix_xattr_userns(
699         struct user_namespace *to, struct user_namespace *from,
700         struct user_namespace *mnt_userns,
701         void *value, size_t size, bool from_user)
702 {
703         struct posix_acl_xattr_header *header = value;
704         struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end;
705         int count;
706         kuid_t uid;
707         kgid_t gid;
708
709         if (!value)
710                 return;
711         if (size < sizeof(struct posix_acl_xattr_header))
712                 return;
713         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
714                 return;
715
716         count = posix_acl_xattr_count(size);
717         if (count < 0)
718                 return;
719         if (count == 0)
720                 return;
721
722         for (end = entry + count; entry != end; entry++) {
723                 switch(le16_to_cpu(entry->e_tag)) {
724                 case ACL_USER:
725                         uid = make_kuid(from, le32_to_cpu(entry->e_id));
726                         if (from_user)
727                                 uid = kuid_from_mnt(mnt_userns, uid);
728                         else
729                                 uid = kuid_into_mnt(mnt_userns, uid);
730                         entry->e_id = cpu_to_le32(from_kuid(to, uid));
731                         break;
732                 case ACL_GROUP:
733                         gid = make_kgid(from, le32_to_cpu(entry->e_id));
734                         if (from_user)
735                                 gid = kgid_from_mnt(mnt_userns, gid);
736                         else
737                                 gid = kgid_into_mnt(mnt_userns, gid);
738                         entry->e_id = cpu_to_le32(from_kgid(to, gid));
739                         break;
740                 default:
741                         break;
742                 }
743         }
744 }
745
746 void posix_acl_fix_xattr_from_user(struct user_namespace *mnt_userns,
747                                    void *value, size_t size)
748 {
749         struct user_namespace *user_ns = current_user_ns();
750         if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
751                 return;
752         posix_acl_fix_xattr_userns(&init_user_ns, user_ns, mnt_userns, value,
753                                    size, true);
754 }
755
756 void posix_acl_fix_xattr_to_user(struct user_namespace *mnt_userns,
757                                  void *value, size_t size)
758 {
759         struct user_namespace *user_ns = current_user_ns();
760         if ((user_ns == &init_user_ns) && (mnt_userns == &init_user_ns))
761                 return;
762         posix_acl_fix_xattr_userns(user_ns, &init_user_ns, mnt_userns, value,
763                                    size, false);
764 }
765
766 /*
767  * Convert from extended attribute to in-memory representation.
768  */
769 struct posix_acl *
770 posix_acl_from_xattr(struct user_namespace *user_ns,
771                      const void *value, size_t size)
772 {
773         const struct posix_acl_xattr_header *header = value;
774         const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end;
775         int count;
776         struct posix_acl *acl;
777         struct posix_acl_entry *acl_e;
778
779         if (!value)
780                 return NULL;
781         if (size < sizeof(struct posix_acl_xattr_header))
782                  return ERR_PTR(-EINVAL);
783         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
784                 return ERR_PTR(-EOPNOTSUPP);
785
786         count = posix_acl_xattr_count(size);
787         if (count < 0)
788                 return ERR_PTR(-EINVAL);
789         if (count == 0)
790                 return NULL;
791         
792         acl = posix_acl_alloc(count, GFP_NOFS);
793         if (!acl)
794                 return ERR_PTR(-ENOMEM);
795         acl_e = acl->a_entries;
796         
797         for (end = entry + count; entry != end; acl_e++, entry++) {
798                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
799                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
800
801                 switch(acl_e->e_tag) {
802                         case ACL_USER_OBJ:
803                         case ACL_GROUP_OBJ:
804                         case ACL_MASK:
805                         case ACL_OTHER:
806                                 break;
807
808                         case ACL_USER:
809                                 acl_e->e_uid =
810                                         make_kuid(user_ns,
811                                                   le32_to_cpu(entry->e_id));
812                                 if (!uid_valid(acl_e->e_uid))
813                                         goto fail;
814                                 break;
815                         case ACL_GROUP:
816                                 acl_e->e_gid =
817                                         make_kgid(user_ns,
818                                                   le32_to_cpu(entry->e_id));
819                                 if (!gid_valid(acl_e->e_gid))
820                                         goto fail;
821                                 break;
822
823                         default:
824                                 goto fail;
825                 }
826         }
827         return acl;
828
829 fail:
830         posix_acl_release(acl);
831         return ERR_PTR(-EINVAL);
832 }
833 EXPORT_SYMBOL (posix_acl_from_xattr);
834
835 /*
836  * Convert from in-memory to extended attribute representation.
837  */
838 int
839 posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl,
840                    void *buffer, size_t size)
841 {
842         struct posix_acl_xattr_header *ext_acl = buffer;
843         struct posix_acl_xattr_entry *ext_entry;
844         int real_size, n;
845
846         real_size = posix_acl_xattr_size(acl->a_count);
847         if (!buffer)
848                 return real_size;
849         if (real_size > size)
850                 return -ERANGE;
851
852         ext_entry = (void *)(ext_acl + 1);
853         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
854
855         for (n=0; n < acl->a_count; n++, ext_entry++) {
856                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
857                 ext_entry->e_tag  = cpu_to_le16(acl_e->e_tag);
858                 ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
859                 switch(acl_e->e_tag) {
860                 case ACL_USER:
861                         ext_entry->e_id =
862                                 cpu_to_le32(from_kuid(user_ns, acl_e->e_uid));
863                         break;
864                 case ACL_GROUP:
865                         ext_entry->e_id =
866                                 cpu_to_le32(from_kgid(user_ns, acl_e->e_gid));
867                         break;
868                 default:
869                         ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
870                         break;
871                 }
872         }
873         return real_size;
874 }
875 EXPORT_SYMBOL (posix_acl_to_xattr);
876
877 static int
878 posix_acl_xattr_get(const struct xattr_handler *handler,
879                     struct dentry *unused, struct inode *inode,
880                     const char *name, void *value, size_t size)
881 {
882         struct posix_acl *acl;
883         int error;
884
885         if (!IS_POSIXACL(inode))
886                 return -EOPNOTSUPP;
887         if (S_ISLNK(inode->i_mode))
888                 return -EOPNOTSUPP;
889
890         acl = get_acl(inode, handler->flags);
891         if (IS_ERR(acl))
892                 return PTR_ERR(acl);
893         if (acl == NULL)
894                 return -ENODATA;
895
896         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
897         posix_acl_release(acl);
898
899         return error;
900 }
901
902 int
903 set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode,
904               int type, struct posix_acl *acl)
905 {
906         if (!IS_POSIXACL(inode))
907                 return -EOPNOTSUPP;
908         if (!inode->i_op->set_acl)
909                 return -EOPNOTSUPP;
910
911         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
912                 return acl ? -EACCES : 0;
913         if (!inode_owner_or_capable(mnt_userns, inode))
914                 return -EPERM;
915
916         if (acl) {
917                 int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl);
918                 if (ret)
919                         return ret;
920         }
921         return inode->i_op->set_acl(mnt_userns, inode, acl, type);
922 }
923 EXPORT_SYMBOL(set_posix_acl);
924
925 static int
926 posix_acl_xattr_set(const struct xattr_handler *handler,
927                            struct user_namespace *mnt_userns,
928                            struct dentry *unused, struct inode *inode,
929                            const char *name, const void *value, size_t size,
930                            int flags)
931 {
932         struct posix_acl *acl = NULL;
933         int ret;
934
935         if (value) {
936                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
937                 if (IS_ERR(acl))
938                         return PTR_ERR(acl);
939         }
940         ret = set_posix_acl(mnt_userns, inode, handler->flags, acl);
941         posix_acl_release(acl);
942         return ret;
943 }
944
945 static bool
946 posix_acl_xattr_list(struct dentry *dentry)
947 {
948         return IS_POSIXACL(d_backing_inode(dentry));
949 }
950
951 const struct xattr_handler posix_acl_access_xattr_handler = {
952         .name = XATTR_NAME_POSIX_ACL_ACCESS,
953         .flags = ACL_TYPE_ACCESS,
954         .list = posix_acl_xattr_list,
955         .get = posix_acl_xattr_get,
956         .set = posix_acl_xattr_set,
957 };
958 EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler);
959
960 const struct xattr_handler posix_acl_default_xattr_handler = {
961         .name = XATTR_NAME_POSIX_ACL_DEFAULT,
962         .flags = ACL_TYPE_DEFAULT,
963         .list = posix_acl_xattr_list,
964         .get = posix_acl_xattr_get,
965         .set = posix_acl_xattr_set,
966 };
967 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
968
969 int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
970                    struct posix_acl *acl, int type)
971 {
972         int error;
973
974         if (type == ACL_TYPE_ACCESS) {
975                 error = posix_acl_update_mode(mnt_userns, inode,
976                                 &inode->i_mode, &acl);
977                 if (error)
978                         return error;
979         }
980
981         inode->i_ctime = current_time(inode);
982         set_cached_acl(inode, type, acl);
983         return 0;
984 }
985
986 int simple_acl_create(struct inode *dir, struct inode *inode)
987 {
988         struct posix_acl *default_acl, *acl;
989         int error;
990
991         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
992         if (error)
993                 return error;
994
995         set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
996         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
997
998         if (default_acl)
999                 posix_acl_release(default_acl);
1000         if (acl)
1001                 posix_acl_release(acl);
1002         return 0;
1003 }