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/fs.h>
11 #include <linux/ext3_jbd.h>
12 #include <linux/ext3_fs.h>
13 #include "xattr.h"
14 #include "acl.h"
15
16 /*
17 * Convert from filesystem to in-memory representation.
18 */
19 static struct posix_acl *
20 ext3_acl_from_disk(const void *value, size_t size)
21 {
22 const char *end = (char *)value + size;
23 int n, count;
24 struct posix_acl *acl;
25
26 if (!value)
27 return NULL;
28 if (size < sizeof(ext3_acl_header))
29 return ERR_PTR(-EINVAL);
30 if (((ext3_acl_header *)value)->a_version !=
31 cpu_to_le32(EXT3_ACL_VERSION))
32 return ERR_PTR(-EINVAL);
33 value = (char *)value + sizeof(ext3_acl_header);
34 count = ext3_acl_count(size);
35 if (count < 0)
36 return ERR_PTR(-EINVAL);
37 if (count == 0)
38 return NULL;
39 acl = posix_acl_alloc(count, GFP_KERNEL);
40 if (!acl)
41 return ERR_PTR(-ENOMEM);
42 for (n=0; n < count; n++) {
43 ext3_acl_entry *entry =
44 (ext3_acl_entry *)value;
45 if ((char *)value + sizeof(ext3_acl_entry_short) > end)
46 goto fail;
47 acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
48 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
49 switch(acl->a_entries[n].e_tag) {
50 case ACL_USER_OBJ:
51 case ACL_GROUP_OBJ:
52 case ACL_MASK:
53 case ACL_OTHER:
54 value = (char *)value +
55 sizeof(ext3_acl_entry_short);
56 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
57 break;
58
59 case ACL_USER:
60 case ACL_GROUP:
61 value = (char *)value + sizeof(ext3_acl_entry);
62 if ((char *)value > end)
63 goto fail;
64 acl->a_entries[n].e_id =
65 le32_to_cpu(entry->e_id);
66 break;
67
68 default:
69 goto fail;
70 }
71 }
72 if (value != end)
73 goto fail;
74 return acl;
75
76 fail:
77 posix_acl_release(acl);
78 return ERR_PTR(-EINVAL);
79 }
80
81 /*
82 * Convert from in-memory to filesystem representation.
83 */
84 static void *
85 ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
86 {
87 ext3_acl_header *ext_acl;
88 char *e;
89 size_t n;
90
91 *size = ext3_acl_size(acl->a_count);
92 ext_acl = (ext3_acl_header *)kmalloc(sizeof(ext3_acl_header) +
93 acl->a_count * sizeof(ext3_acl_entry), GFP_KERNEL);
94 if (!ext_acl)
95 return ERR_PTR(-ENOMEM);
96 ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
97 e = (char *)ext_acl + sizeof(ext3_acl_header);
98 for (n=0; n < acl->a_count; n++) {
99 ext3_acl_entry *entry = (ext3_acl_entry *)e;
100 entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
101 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
102 switch(acl->a_entries[n].e_tag) {
103 case ACL_USER:
104 case ACL_GROUP:
105 entry->e_id =
106 cpu_to_le32(acl->a_entries[n].e_id);
107 e += sizeof(ext3_acl_entry);
108 break;
109
110 case ACL_USER_OBJ:
111 case ACL_GROUP_OBJ:
112 case ACL_MASK:
113 case ACL_OTHER:
114 e += sizeof(ext3_acl_entry_short);
115 break;
116
117 default:
118 goto fail;
119 }
120 }
121 return (char *)ext_acl;
122
123 fail:
124 kfree(ext_acl);
125 return ERR_PTR(-EINVAL);
126 }
127
128 static inline struct posix_acl *
129 ext3_iget_acl(struct inode *inode, struct posix_acl **i_acl)
130 {
131 struct posix_acl *acl = EXT3_ACL_NOT_CACHED;
132
133 spin_lock(&inode->i_lock);
134 if (*i_acl != EXT3_ACL_NOT_CACHED)
135 acl = posix_acl_dup(*i_acl);
136 spin_unlock(&inode->i_lock);
137
138 return acl;
139 }
140
141 static inline void
142 ext3_iset_acl(struct inode *inode, struct posix_acl **i_acl,
143 struct posix_acl *acl)
144 {
145 spin_lock(&inode->i_lock);
146 if (*i_acl != EXT3_ACL_NOT_CACHED)
147 posix_acl_release(*i_acl);
148 *i_acl = posix_acl_dup(acl);
149 spin_unlock(&inode->i_lock);
150 }
151
152 /*
153 * Inode operation get_posix_acl().
154 *
155 * inode->i_sem: don't care
156 */
157 static struct posix_acl *
158 ext3_get_acl(struct inode *inode, int type)
159 {
160 struct ext3_inode_info *ei = EXT3_I(inode);
161 int name_index;
162 char *value = NULL;
163 struct posix_acl *acl;
164 int retval;
165
166 if (!test_opt(inode->i_sb, POSIX_ACL))
167 return NULL;
168
169 switch(type) {
170 case ACL_TYPE_ACCESS:
171 acl = ext3_iget_acl(inode, &ei->i_acl);
172 if (acl != EXT3_ACL_NOT_CACHED)
173 return acl;
174 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
175 break;
176
177 case ACL_TYPE_DEFAULT:
178 acl = ext3_iget_acl(inode, &ei->i_default_acl);
179 if (acl != EXT3_ACL_NOT_CACHED)
180 return acl;
181 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
182 break;
183
184 default:
185 return ERR_PTR(-EINVAL);
186 }
187 retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
188 if (retval > 0) {
189 value = kmalloc(retval, GFP_KERNEL);
190 if (!value)
191 return ERR_PTR(-ENOMEM);
192 retval = ext3_xattr_get(inode, name_index, "", value, retval);
193 }
194 if (retval > 0)
195 acl = ext3_acl_from_disk(value, retval);
196 else if (retval == -ENODATA || retval == -ENOSYS)
197 acl = NULL;
198 else
199 acl = ERR_PTR(retval);
200 if (value)
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_sem: 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;
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 if (value)
271 kfree(value);
272 if (!error) {
273 switch(type) {
274 case ACL_TYPE_ACCESS:
275 ext3_iset_acl(inode, &ei->i_acl, acl);
276 break;
277
278 case ACL_TYPE_DEFAULT:
279 ext3_iset_acl(inode, &ei->i_default_acl, acl);
280 break;
281 }
282 }
283 return error;
284 }
285
286 static int
287 ext3_check_acl(struct inode *inode, int mask)
288 {
289 struct posix_acl *acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
290
291 if (acl) {
292 int error = posix_acl_permission(inode, acl, mask);
293 posix_acl_release(acl);
294 return error;
295 }
296
297 return -EAGAIN;
298 }
299
300 int
301 ext3_permission(struct inode *inode, int mask, struct nameidata *nd)
302 {
303 return generic_permission(inode, mask, ext3_check_acl);
304 }
305
306 /*
307 * Initialize the ACLs of a new inode. Called from ext3_new_inode.
308 *
309 * dir->i_sem: down
310 * inode->i_sem: up (access to inode is still exclusive)
311 */
312 int
313 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
314 {
315 struct posix_acl *acl = NULL;
316 int error = 0;
317
318 if (!S_ISLNK(inode->i_mode)) {
319 if (test_opt(dir->i_sb, POSIX_ACL)) {
320 acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
321 if (IS_ERR(acl))
322 return PTR_ERR(acl);
323 }
324 if (!acl)
325 inode->i_mode &= ~current->fs->umask;
326 }
327 if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
328 struct posix_acl *clone;
329 mode_t mode;
330
331 if (S_ISDIR(inode->i_mode)) {
332 error = ext3_set_acl(handle, inode,
333 ACL_TYPE_DEFAULT, acl);
334 if (error)
335 goto cleanup;
336 }
337 clone = posix_acl_clone(acl, GFP_KERNEL);
338 error = -ENOMEM;
339 if (!clone)
340 goto cleanup;
341
342 mode = inode->i_mode;
343 error = posix_acl_create_masq(clone, &mode);
344 if (error >= 0) {
345 inode->i_mode = mode;
346 if (error > 0) {
347 /* This is an extended ACL */
348 error = ext3_set_acl(handle, inode,
349 ACL_TYPE_ACCESS, clone);
350 }
351 }
352 posix_acl_release(clone);
353 }
354 cleanup:
355 posix_acl_release(acl);
356 return error;
357 }
358
359 /*
360 * Does chmod for an inode that may have an Access Control List. The
361 * inode->i_mode field must be updated to the desired value by the caller
362 * before calling this function.
363 * Returns 0 on success, or a negative error number.
364 *
365 * We change the ACL rather than storing some ACL entries in the file
366 * mode permission bits (which would be more efficient), because that
367 * would break once additional permissions (like ACL_APPEND, ACL_DELETE
368 * for directories) are added. There are no more bits available in the
369 * file mode.
370 *
371 * inode->i_sem: down
372 */
373 int
374 ext3_acl_chmod(struct inode *inode)
375 {
376 struct posix_acl *acl, *clone;
377 int error;
378
379 if (S_ISLNK(inode->i_mode))
380 return -EOPNOTSUPP;
381 if (!test_opt(inode->i_sb, POSIX_ACL))
382 return 0;
383 acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
384 if (IS_ERR(acl) || !acl)
385 return PTR_ERR(acl);
386 clone = posix_acl_clone(acl, GFP_KERNEL);
387 posix_acl_release(acl);
388 if (!clone)
389 return -ENOMEM;
390 error = posix_acl_chmod_masq(clone, inode->i_mode);
391 if (!error) {
392 handle_t *handle;
393 int retries = 0;
394
395 retry:
396 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
397 if (IS_ERR(handle)) {
398 error = PTR_ERR(handle);
399 ext3_std_error(inode->i_sb, error);
400 goto out;
401 }
402 error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
403 ext3_journal_stop(handle);
404 if (error == -ENOSPC &&
405 ext3_should_retry_alloc(inode->i_sb, &retries))
406 goto retry;
407 }
408 out:
409 posix_acl_release(clone);
410 return error;
411 }
412
413 /*
414 * Extended attribute handlers
415 */
416 static size_t
417 ext3_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len,
418 const char *name, size_t name_len)
419 {
420 const size_t size = sizeof(XATTR_NAME_ACL_ACCESS);
421
422 if (!test_opt(inode->i_sb, POSIX_ACL))
423 return 0;
424 if (list && size <= list_len)
425 memcpy(list, XATTR_NAME_ACL_ACCESS, size);
426 return size;
427 }
428
429 static size_t
430 ext3_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len,
431 const char *name, size_t name_len)
432 {
433 const size_t size = sizeof(XATTR_NAME_ACL_DEFAULT);
434
435 if (!test_opt(inode->i_sb, POSIX_ACL))
436 return 0;
437 if (list && size <= list_len)
438 memcpy(list, XATTR_NAME_ACL_DEFAULT, size);
439 return size;
440 }
441
442 static int
443 ext3_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
444 {
445 struct posix_acl *acl;
446 int error;
447
448 if (!test_opt(inode->i_sb, POSIX_ACL))
449 return -EOPNOTSUPP;
450
451 acl = ext3_get_acl(inode, type);
452 if (IS_ERR(acl))
453 return PTR_ERR(acl);
454 if (acl == NULL)
455 return -ENODATA;
456 error = posix_acl_to_xattr(acl, buffer, size);
457 posix_acl_release(acl);
458
459 return error;
460 }
461
462 static int
463 ext3_xattr_get_acl_access(struct inode *inode, const char *name,
464 void *buffer, size_t size)
465 {
466 if (strcmp(name, "") != 0)
467 return -EINVAL;
468 return ext3_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
469 }
470
471 static int
472 ext3_xattr_get_acl_default(struct inode *inode, const char *name,
473 void *buffer, size_t size)
474 {
475 if (strcmp(name, "") != 0)
476 return -EINVAL;
477 return ext3_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
478 }
479
480 static int
481 ext3_xattr_set_acl(struct inode *inode, int type, const void *value,
482 size_t size)
483 {
484 handle_t *handle;
485 struct posix_acl *acl;
486 int error, retries = 0;
487
488 if (!test_opt(inode->i_sb, POSIX_ACL))
489 return -EOPNOTSUPP;
490 if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
491 return -EPERM;
492
493 if (value) {
494 acl = posix_acl_from_xattr(value, size);
495 if (IS_ERR(acl))
496 return PTR_ERR(acl);
497 else if (acl) {
498 error = posix_acl_valid(acl);
499 if (error)
500 goto release_and_out;
501 }
502 } else
503 acl = NULL;
504
505 retry:
506 handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS);
507 if (IS_ERR(handle))
508 return PTR_ERR(handle);
509 error = ext3_set_acl(handle, inode, type, acl);
510 ext3_journal_stop(handle);
511 if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
512 goto retry;
513
514 release_and_out:
515 posix_acl_release(acl);
516 return error;
517 }
518
519 static int
520 ext3_xattr_set_acl_access(struct inode *inode, const char *name,
521 const void *value, size_t size, int flags)
522 {
523 if (strcmp(name, "") != 0)
524 return -EINVAL;
525 return ext3_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
526 }
527
528 static int
529 ext3_xattr_set_acl_default(struct inode *inode, const char *name,
530 const void *value, size_t size, int flags)
531 {
532 if (strcmp(name, "") != 0)
533 return -EINVAL;
534 return ext3_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
535 }
536
537 struct xattr_handler ext3_xattr_acl_access_handler = {
538 .prefix = XATTR_NAME_ACL_ACCESS,
539 .list = ext3_xattr_list_acl_access,
540 .get = ext3_xattr_get_acl_access,
541 .set = ext3_xattr_set_acl_access,
542 };
543
544 struct xattr_handler ext3_xattr_acl_default_handler = {
545 .prefix = XATTR_NAME_ACL_DEFAULT,
546 .list = ext3_xattr_list_acl_default,
547 .get = ext3_xattr_get_acl_default,
548 .set = ext3_xattr_set_acl_default,
549 };
550
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