Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6
[linux-2.6] / fs / ext4 / acl.c
1 /*
2  * linux/fs/ext4/acl.c
3  *
4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5  */
6
7 #include <linux/init.h>
8 #include <linux/sched.h>
9 #include <linux/slab.h>
10 #include <linux/capability.h>
11 #include <linux/fs.h>
12 #include "ext4_jbd2.h"
13 #include "ext4.h"
14 #include "xattr.h"
15 #include "acl.h"
16
17 /*
18  * Convert from filesystem to in-memory representation.
19  */
20 static struct posix_acl *
21 ext4_acl_from_disk(const void *value, size_t size)
22 {
23         const char *end = (char *)value + size;
24         int n, count;
25         struct posix_acl *acl;
26
27         if (!value)
28                 return NULL;
29         if (size < sizeof(ext4_acl_header))
30                  return ERR_PTR(-EINVAL);
31         if (((ext4_acl_header *)value)->a_version !=
32             cpu_to_le32(EXT4_ACL_VERSION))
33                 return ERR_PTR(-EINVAL);
34         value = (char *)value + sizeof(ext4_acl_header);
35         count = ext4_acl_count(size);
36         if (count < 0)
37                 return ERR_PTR(-EINVAL);
38         if (count == 0)
39                 return NULL;
40         acl = posix_acl_alloc(count, GFP_NOFS);
41         if (!acl)
42                 return ERR_PTR(-ENOMEM);
43         for (n = 0; n < count; n++) {
44                 ext4_acl_entry *entry =
45                         (ext4_acl_entry *)value;
46                 if ((char *)value + sizeof(ext4_acl_entry_short) > end)
47                         goto fail;
48                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
49                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
50
51                 switch (acl->a_entries[n].e_tag) {
52                 case ACL_USER_OBJ:
53                 case ACL_GROUP_OBJ:
54                 case ACL_MASK:
55                 case ACL_OTHER:
56                         value = (char *)value +
57                                 sizeof(ext4_acl_entry_short);
58                         acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
59                         break;
60
61                 case ACL_USER:
62                 case ACL_GROUP:
63                         value = (char *)value + sizeof(ext4_acl_entry);
64                         if ((char *)value > end)
65                                 goto fail;
66                         acl->a_entries[n].e_id =
67                                 le32_to_cpu(entry->e_id);
68                         break;
69
70                 default:
71                         goto fail;
72                 }
73         }
74         if (value != end)
75                 goto fail;
76         return acl;
77
78 fail:
79         posix_acl_release(acl);
80         return ERR_PTR(-EINVAL);
81 }
82
83 /*
84  * Convert from in-memory to filesystem representation.
85  */
86 static void *
87 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
88 {
89         ext4_acl_header *ext_acl;
90         char *e;
91         size_t n;
92
93         *size = ext4_acl_size(acl->a_count);
94         ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
95                         sizeof(ext4_acl_entry), GFP_NOFS);
96         if (!ext_acl)
97                 return ERR_PTR(-ENOMEM);
98         ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
99         e = (char *)ext_acl + sizeof(ext4_acl_header);
100         for (n = 0; n < acl->a_count; n++) {
101                 ext4_acl_entry *entry = (ext4_acl_entry *)e;
102                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
103                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
104                 switch (acl->a_entries[n].e_tag) {
105                 case ACL_USER:
106                 case ACL_GROUP:
107                         entry->e_id = cpu_to_le32(acl->a_entries[n].e_id);
108                         e += sizeof(ext4_acl_entry);
109                         break;
110
111                 case ACL_USER_OBJ:
112                 case ACL_GROUP_OBJ:
113                 case ACL_MASK:
114                 case ACL_OTHER:
115                         e += sizeof(ext4_acl_entry_short);
116                         break;
117
118                 default:
119                         goto fail;
120                 }
121         }
122         return (char *)ext_acl;
123
124 fail:
125         kfree(ext_acl);
126         return ERR_PTR(-EINVAL);
127 }
128
129 static inline struct posix_acl *
130 ext4_iget_acl(struct inode *inode, struct posix_acl **i_acl)
131 {
132         struct posix_acl *acl = ACCESS_ONCE(*i_acl);
133
134         if (acl) {
135                 spin_lock(&inode->i_lock);
136                 acl = *i_acl;
137                 if (acl != EXT4_ACL_NOT_CACHED)
138                         acl = posix_acl_dup(acl);
139                 spin_unlock(&inode->i_lock);
140         }
141
142         return acl;
143 }
144
145 static inline void
146 ext4_iset_acl(struct inode *inode, struct posix_acl **i_acl,
147                 struct posix_acl *acl)
148 {
149         spin_lock(&inode->i_lock);
150         if (*i_acl != EXT4_ACL_NOT_CACHED)
151                 posix_acl_release(*i_acl);
152         *i_acl = posix_acl_dup(acl);
153         spin_unlock(&inode->i_lock);
154 }
155
156 /*
157  * Inode operation get_posix_acl().
158  *
159  * inode->i_mutex: don't care
160  */
161 static struct posix_acl *
162 ext4_get_acl(struct inode *inode, int type)
163 {
164         struct ext4_inode_info *ei = EXT4_I(inode);
165         int name_index;
166         char *value = NULL;
167         struct posix_acl *acl;
168         int retval;
169
170         if (!test_opt(inode->i_sb, POSIX_ACL))
171                 return NULL;
172
173         switch (type) {
174         case ACL_TYPE_ACCESS:
175                 acl = ext4_iget_acl(inode, &ei->i_acl);
176                 if (acl != EXT4_ACL_NOT_CACHED)
177                         return acl;
178                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
179                 break;
180
181         case ACL_TYPE_DEFAULT:
182                 acl = ext4_iget_acl(inode, &ei->i_default_acl);
183                 if (acl != EXT4_ACL_NOT_CACHED)
184                         return acl;
185                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
186                 break;
187
188         default:
189                 return ERR_PTR(-EINVAL);
190         }
191         retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
192         if (retval > 0) {
193                 value = kmalloc(retval, GFP_NOFS);
194                 if (!value)
195                         return ERR_PTR(-ENOMEM);
196                 retval = ext4_xattr_get(inode, name_index, "", value, retval);
197         }
198         if (retval > 0)
199                 acl = ext4_acl_from_disk(value, retval);
200         else if (retval == -ENODATA || retval == -ENOSYS)
201                 acl = NULL;
202         else
203                 acl = ERR_PTR(retval);
204         kfree(value);
205
206         if (!IS_ERR(acl)) {
207                 switch (type) {
208                 case ACL_TYPE_ACCESS:
209                         ext4_iset_acl(inode, &ei->i_acl, acl);
210                         break;
211
212                 case ACL_TYPE_DEFAULT:
213                         ext4_iset_acl(inode, &ei->i_default_acl, acl);
214                         break;
215                 }
216         }
217         return acl;
218 }
219
220 /*
221  * Set the access or default ACL of an inode.
222  *
223  * inode->i_mutex: down unless called from ext4_new_inode
224  */
225 static int
226 ext4_set_acl(handle_t *handle, struct inode *inode, int type,
227              struct posix_acl *acl)
228 {
229         struct ext4_inode_info *ei = EXT4_I(inode);
230         int name_index;
231         void *value = NULL;
232         size_t size = 0;
233         int error;
234
235         if (S_ISLNK(inode->i_mode))
236                 return -EOPNOTSUPP;
237
238         switch (type) {
239         case ACL_TYPE_ACCESS:
240                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
241                 if (acl) {
242                         mode_t mode = inode->i_mode;
243                         error = posix_acl_equiv_mode(acl, &mode);
244                         if (error < 0)
245                                 return error;
246                         else {
247                                 inode->i_mode = mode;
248                                 ext4_mark_inode_dirty(handle, inode);
249                                 if (error == 0)
250                                         acl = NULL;
251                         }
252                 }
253                 break;
254
255         case ACL_TYPE_DEFAULT:
256                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
257                 if (!S_ISDIR(inode->i_mode))
258                         return acl ? -EACCES : 0;
259                 break;
260
261         default:
262                 return -EINVAL;
263         }
264         if (acl) {
265                 value = ext4_acl_to_disk(acl, &size);
266                 if (IS_ERR(value))
267                         return (int)PTR_ERR(value);
268         }
269
270         error = ext4_xattr_set_handle(handle, inode, name_index, "",
271                                       value, size, 0);
272
273         kfree(value);
274         if (!error) {
275                 switch (type) {
276                 case ACL_TYPE_ACCESS:
277                         ext4_iset_acl(inode, &ei->i_acl, acl);
278                         break;
279
280                 case ACL_TYPE_DEFAULT:
281                         ext4_iset_acl(inode, &ei->i_default_acl, acl);
282                         break;
283                 }
284         }
285         return error;
286 }
287
288 static int
289 ext4_check_acl(struct inode *inode, int mask)
290 {
291         struct posix_acl *acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
292
293         if (IS_ERR(acl))
294                 return PTR_ERR(acl);
295         if (acl) {
296                 int error = posix_acl_permission(inode, acl, mask);
297                 posix_acl_release(acl);
298                 return error;
299         }
300
301         return -EAGAIN;
302 }
303
304 int
305 ext4_permission(struct inode *inode, int mask)
306 {
307         return generic_permission(inode, mask, ext4_check_acl);
308 }
309
310 /*
311  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
312  *
313  * dir->i_mutex: down
314  * inode->i_mutex: up (access to inode is still exclusive)
315  */
316 int
317 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
318 {
319         struct posix_acl *acl = NULL;
320         int error = 0;
321
322         if (!S_ISLNK(inode->i_mode)) {
323                 if (test_opt(dir->i_sb, POSIX_ACL)) {
324                         acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT);
325                         if (IS_ERR(acl))
326                                 return PTR_ERR(acl);
327                 }
328                 if (!acl)
329                         inode->i_mode &= ~current_umask();
330         }
331         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
332                 struct posix_acl *clone;
333                 mode_t mode;
334
335                 if (S_ISDIR(inode->i_mode)) {
336                         error = ext4_set_acl(handle, inode,
337                                              ACL_TYPE_DEFAULT, acl);
338                         if (error)
339                                 goto cleanup;
340                 }
341                 clone = posix_acl_clone(acl, GFP_NOFS);
342                 error = -ENOMEM;
343                 if (!clone)
344                         goto cleanup;
345
346                 mode = inode->i_mode;
347                 error = posix_acl_create_masq(clone, &mode);
348                 if (error >= 0) {
349                         inode->i_mode = mode;
350                         if (error > 0) {
351                                 /* This is an extended ACL */
352                                 error = ext4_set_acl(handle, inode,
353                                                      ACL_TYPE_ACCESS, clone);
354                         }
355                 }
356                 posix_acl_release(clone);
357         }
358 cleanup:
359         posix_acl_release(acl);
360         return error;
361 }
362
363 /*
364  * Does chmod for an inode that may have an Access Control List. The
365  * inode->i_mode field must be updated to the desired value by the caller
366  * before calling this function.
367  * Returns 0 on success, or a negative error number.
368  *
369  * We change the ACL rather than storing some ACL entries in the file
370  * mode permission bits (which would be more efficient), because that
371  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
372  * for directories) are added. There are no more bits available in the
373  * file mode.
374  *
375  * inode->i_mutex: down
376  */
377 int
378 ext4_acl_chmod(struct inode *inode)
379 {
380         struct posix_acl *acl, *clone;
381         int error;
382
383         if (S_ISLNK(inode->i_mode))
384                 return -EOPNOTSUPP;
385         if (!test_opt(inode->i_sb, POSIX_ACL))
386                 return 0;
387         acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
388         if (IS_ERR(acl) || !acl)
389                 return PTR_ERR(acl);
390         clone = posix_acl_clone(acl, GFP_KERNEL);
391         posix_acl_release(acl);
392         if (!clone)
393                 return -ENOMEM;
394         error = posix_acl_chmod_masq(clone, inode->i_mode);
395         if (!error) {
396                 handle_t *handle;
397                 int retries = 0;
398
399         retry:
400                 handle = ext4_journal_start(inode,
401                                 EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
402                 if (IS_ERR(handle)) {
403                         error = PTR_ERR(handle);
404                         ext4_std_error(inode->i_sb, error);
405                         goto out;
406                 }
407                 error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
408                 ext4_journal_stop(handle);
409                 if (error == -ENOSPC &&
410                     ext4_should_retry_alloc(inode->i_sb, &retries))
411                         goto retry;
412         }
413 out:
414         posix_acl_release(clone);
415         return error;
416 }
417
418 /*
419  * Extended attribute handlers
420  */
421 static size_t
422 ext4_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len,
423                            const char *name, size_t name_len)
424 {
425         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
426
427         if (!test_opt(inode->i_sb, POSIX_ACL))
428                 return 0;
429         if (list && size <= list_len)
430                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
431         return size;
432 }
433
434 static size_t
435 ext4_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len,
436                             const char *name, size_t name_len)
437 {
438         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
439
440         if (!test_opt(inode->i_sb, POSIX_ACL))
441                 return 0;
442         if (list && size <= list_len)
443                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
444         return size;
445 }
446
447 static int
448 ext4_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
449 {
450         struct posix_acl *acl;
451         int error;
452
453         if (!test_opt(inode->i_sb, POSIX_ACL))
454                 return -EOPNOTSUPP;
455
456         acl = ext4_get_acl(inode, type);
457         if (IS_ERR(acl))
458                 return PTR_ERR(acl);
459         if (acl == NULL)
460                 return -ENODATA;
461         error = posix_acl_to_xattr(acl, buffer, size);
462         posix_acl_release(acl);
463
464         return error;
465 }
466
467 static int
468 ext4_xattr_get_acl_access(struct inode *inode, const char *name,
469                           void *buffer, size_t size)
470 {
471         if (strcmp(name, "") != 0)
472                 return -EINVAL;
473         return ext4_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
474 }
475
476 static int
477 ext4_xattr_get_acl_default(struct inode *inode, const char *name,
478                            void *buffer, size_t size)
479 {
480         if (strcmp(name, "") != 0)
481                 return -EINVAL;
482         return ext4_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
483 }
484
485 static int
486 ext4_xattr_set_acl(struct inode *inode, int type, const void *value,
487                    size_t size)
488 {
489         handle_t *handle;
490         struct posix_acl *acl;
491         int error, retries = 0;
492
493         if (!test_opt(inode->i_sb, POSIX_ACL))
494                 return -EOPNOTSUPP;
495         if (!is_owner_or_cap(inode))
496                 return -EPERM;
497
498         if (value) {
499                 acl = posix_acl_from_xattr(value, size);
500                 if (IS_ERR(acl))
501                         return PTR_ERR(acl);
502                 else if (acl) {
503                         error = posix_acl_valid(acl);
504                         if (error)
505                                 goto release_and_out;
506                 }
507         } else
508                 acl = NULL;
509
510 retry:
511         handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
512         if (IS_ERR(handle))
513                 return PTR_ERR(handle);
514         error = ext4_set_acl(handle, inode, type, acl);
515         ext4_journal_stop(handle);
516         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
517                 goto retry;
518
519 release_and_out:
520         posix_acl_release(acl);
521         return error;
522 }
523
524 static int
525 ext4_xattr_set_acl_access(struct inode *inode, const char *name,
526                           const void *value, size_t size, int flags)
527 {
528         if (strcmp(name, "") != 0)
529                 return -EINVAL;
530         return ext4_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
531 }
532
533 static int
534 ext4_xattr_set_acl_default(struct inode *inode, const char *name,
535                            const void *value, size_t size, int flags)
536 {
537         if (strcmp(name, "") != 0)
538                 return -EINVAL;
539         return ext4_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
540 }
541
542 struct xattr_handler ext4_xattr_acl_access_handler = {
543         .prefix = POSIX_ACL_XATTR_ACCESS,
544         .list   = ext4_xattr_list_acl_access,
545         .get    = ext4_xattr_get_acl_access,
546         .set    = ext4_xattr_set_acl_access,
547 };
548
549 struct xattr_handler ext4_xattr_acl_default_handler = {
550         .prefix = POSIX_ACL_XATTR_DEFAULT,
551         .list   = ext4_xattr_list_acl_default,
552         .get    = ext4_xattr_get_acl_default,
553         .set    = ext4_xattr_set_acl_default,
554 };