reiserfs: fixup xattr_root caching
[linux-2.6.git] / fs / ext3 / acl.c
1 /*
2  * linux/fs/ext3/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 <linux/ext3_jbd.h>
13 #include <linux/ext3_fs.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 ext3_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(ext3_acl_header))
30                  return ERR_PTR(-EINVAL);
31         if (((ext3_acl_header *)value)->a_version !=
32             cpu_to_le32(EXT3_ACL_VERSION))
33                 return ERR_PTR(-EINVAL);
34         value = (char *)value + sizeof(ext3_acl_header);
35         count = ext3_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                 ext3_acl_entry *entry =
45                         (ext3_acl_entry *)value;
46                 if ((char *)value + sizeof(ext3_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                 switch(acl->a_entries[n].e_tag) {
51                         case ACL_USER_OBJ:
52                         case ACL_GROUP_OBJ:
53                         case ACL_MASK:
54                         case ACL_OTHER:
55                                 value = (char *)value +
56                                         sizeof(ext3_acl_entry_short);
57                                 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
58                                 break;
59
60                         case ACL_USER:
61                         case ACL_GROUP:
62                                 value = (char *)value + sizeof(ext3_acl_entry);
63                                 if ((char *)value > end)
64                                         goto fail;
65                                 acl->a_entries[n].e_id =
66                                         le32_to_cpu(entry->e_id);
67                                 break;
68
69                         default:
70                                 goto fail;
71                 }
72         }
73         if (value != end)
74                 goto fail;
75         return acl;
76
77 fail:
78         posix_acl_release(acl);
79         return ERR_PTR(-EINVAL);
80 }
81
82 /*
83  * Convert from in-memory to filesystem representation.
84  */
85 static void *
86 ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
87 {
88         ext3_acl_header *ext_acl;
89         char *e;
90         size_t n;
91
92         *size = ext3_acl_size(acl->a_count);
93         ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
94                         sizeof(ext3_acl_entry), GFP_NOFS);
95         if (!ext_acl)
96                 return ERR_PTR(-ENOMEM);
97         ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
98         e = (char *)ext_acl + sizeof(ext3_acl_header);
99         for (n=0; n < acl->a_count; n++) {
100                 ext3_acl_entry *entry = (ext3_acl_entry *)e;
101                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
102                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
103                 switch(acl->a_entries[n].e_tag) {
104                         case ACL_USER:
105                         case ACL_GROUP:
106                                 entry->e_id =
107                                         cpu_to_le32(acl->a_entries[n].e_id);
108                                 e += sizeof(ext3_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(ext3_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 ext3_iget_acl(struct inode *inode, struct posix_acl **i_acl)
131 {
132         struct posix_acl *acl = EXT3_ACL_NOT_CACHED;
133
134         spin_lock(&inode->i_lock);
135         if (*i_acl != EXT3_ACL_NOT_CACHED)
136                 acl = posix_acl_dup(*i_acl);
137         spin_unlock(&inode->i_lock);
138
139         return acl;
140 }
141
142 static inline void
143 ext3_iset_acl(struct inode *inode, struct posix_acl **i_acl,
144                   struct posix_acl *acl)
145 {
146         spin_lock(&inode->i_lock);
147         if (*i_acl != EXT3_ACL_NOT_CACHED)
148                 posix_acl_release(*i_acl);
149         *i_acl = posix_acl_dup(acl);
150         spin_unlock(&inode->i_lock);
151 }
152
153 /*
154  * Inode operation get_posix_acl().
155  *
156  * inode->i_mutex: don't care
157  */
158 static struct posix_acl *
159 ext3_get_acl(struct inode *inode, int type)
160 {
161         struct ext3_inode_info *ei = EXT3_I(inode);
162         int name_index;
163         char *value = NULL;
164         struct posix_acl *acl;
165         int retval;
166
167         if (!test_opt(inode->i_sb, POSIX_ACL))
168                 return NULL;
169
170         switch(type) {
171                 case ACL_TYPE_ACCESS:
172                         acl = ext3_iget_acl(inode, &ei->i_acl);
173                         if (acl != EXT3_ACL_NOT_CACHED)
174                                 return acl;
175                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
176                         break;
177
178                 case ACL_TYPE_DEFAULT:
179                         acl = ext3_iget_acl(inode, &ei->i_default_acl);
180                         if (acl != EXT3_ACL_NOT_CACHED)
181                                 return acl;
182                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
183                         break;
184
185                 default:
186                         return ERR_PTR(-EINVAL);
187         }
188         retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
189         if (retval > 0) {
190                 value = kmalloc(retval, GFP_NOFS);
191                 if (!value)
192                         return ERR_PTR(-ENOMEM);
193                 retval = ext3_xattr_get(inode, name_index, "", value, retval);
194         }
195         if (retval > 0)
196                 acl = ext3_acl_from_disk(value, retval);
197         else if (retval == -ENODATA || retval == -ENOSYS)
198                 acl = NULL;
199         else
200                 acl = ERR_PTR(retval);
201         kfree(value);
202
203         if (!IS_ERR(acl)) {
204                 switch(type) {
205                         case ACL_TYPE_ACCESS:
206                                 ext3_iset_acl(inode, &ei->i_acl, acl);
207                                 break;
208
209                         case ACL_TYPE_DEFAULT:
210                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
211                                 break;
212                 }
213         }
214         return acl;
215 }
216
217 /*
218  * Set the access or default ACL of an inode.
219  *
220  * inode->i_mutex: down unless called from ext3_new_inode
221  */
222 static int
223 ext3_set_acl(handle_t *handle, struct inode *inode, int type,
224              struct posix_acl *acl)
225 {
226         struct ext3_inode_info *ei = EXT3_I(inode);
227         int name_index;
228         void *value = NULL;
229         size_t size = 0;
230         int error;
231
232         if (S_ISLNK(inode->i_mode))
233                 return -EOPNOTSUPP;
234
235         switch(type) {
236                 case ACL_TYPE_ACCESS:
237                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
238                         if (acl) {
239                                 mode_t mode = inode->i_mode;
240                                 error = posix_acl_equiv_mode(acl, &mode);
241                                 if (error < 0)
242                                         return error;
243                                 else {
244                                         inode->i_mode = mode;
245                                         ext3_mark_inode_dirty(handle, inode);
246                                         if (error == 0)
247                                                 acl = NULL;
248                                 }
249                         }
250                         break;
251
252                 case ACL_TYPE_DEFAULT:
253                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
254                         if (!S_ISDIR(inode->i_mode))
255                                 return acl ? -EACCES : 0;
256                         break;
257
258                 default:
259                         return -EINVAL;
260         }
261         if (acl) {
262                 value = ext3_acl_to_disk(acl, &size);
263                 if (IS_ERR(value))
264                         return (int)PTR_ERR(value);
265         }
266
267         error = ext3_xattr_set_handle(handle, inode, name_index, "",
268                                       value, size, 0);
269
270         kfree(value);
271         if (!error) {
272                 switch(type) {
273                         case ACL_TYPE_ACCESS:
274                                 ext3_iset_acl(inode, &ei->i_acl, acl);
275                                 break;
276
277                         case ACL_TYPE_DEFAULT:
278                                 ext3_iset_acl(inode, &ei->i_default_acl, acl);
279                                 break;
280                 }
281         }
282         return error;
283 }
284
285 static int
286 ext3_check_acl(struct inode *inode, int mask)
287 {
288         struct posix_acl *acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
289
290         if (IS_ERR(acl))
291                 return PTR_ERR(acl);
292         if (acl) {
293                 int error = posix_acl_permission(inode, acl, mask);
294                 posix_acl_release(acl);
295                 return error;
296         }
297
298         return -EAGAIN;
299 }
300
301 int
302 ext3_permission(struct inode *inode, int mask)
303 {
304         return generic_permission(inode, mask, ext3_check_acl);
305 }
306
307 /*
308  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
309  *
310  * dir->i_mutex: down
311  * inode->i_mutex: up (access to inode is still exclusive)
312  */
313 int
314 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
315 {
316         struct posix_acl *acl = NULL;
317         int error = 0;
318
319         if (!S_ISLNK(inode->i_mode)) {
320                 if (test_opt(dir->i_sb, POSIX_ACL)) {
321                         acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
322                         if (IS_ERR(acl))
323                                 return PTR_ERR(acl);
324                 }
325                 if (!acl)
326                         inode->i_mode &= ~current_umask();
327         }
328         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
329                 struct posix_acl *clone;
330                 mode_t mode;
331
332                 if (S_ISDIR(inode->i_mode)) {
333                         error = ext3_set_acl(handle, inode,
334                                              ACL_TYPE_DEFAULT, acl);
335                         if (error)
336                                 goto cleanup;
337                 }
338                 clone = posix_acl_clone(acl, GFP_NOFS);
339                 error = -ENOMEM;
340                 if (!clone)
341                         goto cleanup;
342
343                 mode = inode->i_mode;
344                 error = posix_acl_create_masq(clone, &mode);
345                 if (error >= 0) {
346                         inode->i_mode = mode;
347                         if (error > 0) {
348                                 /* This is an extended ACL */
349                                 error = ext3_set_acl(handle, inode,
350                                                      ACL_TYPE_ACCESS, clone);
351                         }
352                 }
353                 posix_acl_release(clone);
354         }
355 cleanup:
356         posix_acl_release(acl);
357         return error;
358 }
359
360 /*
361  * Does chmod for an inode that may have an Access Control List. The
362  * inode->i_mode field must be updated to the desired value by the caller
363  * before calling this function.
364  * Returns 0 on success, or a negative error number.
365  *
366  * We change the ACL rather than storing some ACL entries in the file
367  * mode permission bits (which would be more efficient), because that
368  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
369  * for directories) are added. There are no more bits available in the
370  * file mode.
371  *
372  * inode->i_mutex: down
373  */
374 int
375 ext3_acl_chmod(struct inode *inode)
376 {
377         struct posix_acl *acl, *clone;
378         int error;
379
380         if (S_ISLNK(inode->i_mode))
381                 return -EOPNOTSUPP;
382         if (!test_opt(inode->i_sb, POSIX_ACL))
383                 return 0;
384         acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
385         if (IS_ERR(acl) || !acl)
386                 return PTR_ERR(acl);
387         clone = posix_acl_clone(acl, GFP_KERNEL);
388         posix_acl_release(acl);
389         if (!clone)
390                 return -ENOMEM;
391         error = posix_acl_chmod_masq(clone, inode->i_mode);
392         if (!error) {
393                 handle_t *handle;
394                 int retries = 0;
395
396         retry:
397                 handle = ext3_journal_start(inode,
398                                 EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
399                 if (IS_ERR(handle)) {
400                         error = PTR_ERR(handle);
401                         ext3_std_error(inode->i_sb, error);
402                         goto out;
403                 }
404                 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
405                 ext3_journal_stop(handle);
406                 if (error == -ENOSPC &&
407                     ext3_should_retry_alloc(inode->i_sb, &retries))
408                         goto retry;
409         }
410 out:
411         posix_acl_release(clone);
412         return error;
413 }
414
415 /*
416  * Extended attribute handlers
417  */
418 static size_t
419 ext3_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len,
420                            const char *name, size_t name_len)
421 {
422         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
423
424         if (!test_opt(inode->i_sb, POSIX_ACL))
425                 return 0;
426         if (list && size <= list_len)
427                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
428         return size;
429 }
430
431 static size_t
432 ext3_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len,
433                             const char *name, size_t name_len)
434 {
435         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
436
437         if (!test_opt(inode->i_sb, POSIX_ACL))
438                 return 0;
439         if (list && size <= list_len)
440                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
441         return size;
442 }
443
444 static int
445 ext3_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
446 {
447         struct posix_acl *acl;
448         int error;
449
450         if (!test_opt(inode->i_sb, POSIX_ACL))
451                 return -EOPNOTSUPP;
452
453         acl = ext3_get_acl(inode, type);
454         if (IS_ERR(acl))
455                 return PTR_ERR(acl);
456         if (acl == NULL)
457                 return -ENODATA;
458         error = posix_acl_to_xattr(acl, buffer, size);
459         posix_acl_release(acl);
460
461         return error;
462 }
463
464 static int
465 ext3_xattr_get_acl_access(struct inode *inode, const char *name,
466                           void *buffer, size_t size)
467 {
468         if (strcmp(name, "") != 0)
469                 return -EINVAL;
470         return ext3_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
471 }
472
473 static int
474 ext3_xattr_get_acl_default(struct inode *inode, const char *name,
475                            void *buffer, size_t size)
476 {
477         if (strcmp(name, "") != 0)
478                 return -EINVAL;
479         return ext3_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
480 }
481
482 static int
483 ext3_xattr_set_acl(struct inode *inode, int type, const void *value,
484                    size_t size)
485 {
486         handle_t *handle;
487         struct posix_acl *acl;
488         int error, retries = 0;
489
490         if (!test_opt(inode->i_sb, POSIX_ACL))
491                 return -EOPNOTSUPP;
492         if (!is_owner_or_cap(inode))
493                 return -EPERM;
494
495         if (value) {
496                 acl = posix_acl_from_xattr(value, size);
497                 if (IS_ERR(acl))
498                         return PTR_ERR(acl);
499                 else if (acl) {
500                         error = posix_acl_valid(acl);
501                         if (error)
502                                 goto release_and_out;
503                 }
504         } else
505                 acl = NULL;
506
507 retry:
508         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
509         if (IS_ERR(handle))
510                 return PTR_ERR(handle);
511         error = ext3_set_acl(handle, inode, type, acl);
512         ext3_journal_stop(handle);
513         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
514                 goto retry;
515
516 release_and_out:
517         posix_acl_release(acl);
518         return error;
519 }
520
521 static int
522 ext3_xattr_set_acl_access(struct inode *inode, const char *name,
523                           const void *value, size_t size, int flags)
524 {
525         if (strcmp(name, "") != 0)
526                 return -EINVAL;
527         return ext3_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
528 }
529
530 static int
531 ext3_xattr_set_acl_default(struct inode *inode, const char *name,
532                            const void *value, size_t size, int flags)
533 {
534         if (strcmp(name, "") != 0)
535                 return -EINVAL;
536         return ext3_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
537 }
538
539 struct xattr_handler ext3_xattr_acl_access_handler = {
540         .prefix = POSIX_ACL_XATTR_ACCESS,
541         .list   = ext3_xattr_list_acl_access,
542         .get    = ext3_xattr_get_acl_access,
543         .set    = ext3_xattr_set_acl_access,
544 };
545
546 struct xattr_handler ext3_xattr_acl_default_handler = {
547         .prefix = POSIX_ACL_XATTR_DEFAULT,
548         .list   = ext3_xattr_list_acl_default,
549         .get    = ext3_xattr_get_acl_default,
550         .set    = ext3_xattr_set_acl_default,
551 };