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Linux/fs/posix_acl.c

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

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