1 /*
2 * linux/fs/ext2/acl.c
3 *
4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
5 */
6
7 #include <linux/capability.h>
8 #include <linux/init.h>
9 #include <linux/sched.h>
10 #include <linux/slab.h>
11 #include <linux/fs.h>
12 #include "ext2.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 ext2_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(ext2_acl_header))
29 return ERR_PTR(-EINVAL);
30 if (((ext2_acl_header *)value)->a_version !=
31 cpu_to_le32(EXT2_ACL_VERSION))
32 return ERR_PTR(-EINVAL);
33 value = (char *)value + sizeof(ext2_acl_header);
34 count = ext2_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 ext2_acl_entry *entry =
44 (ext2_acl_entry *)value;
45 if ((char *)value + sizeof(ext2_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(ext2_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(ext2_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 ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
86 {
87 ext2_acl_header *ext_acl;
88 char *e;
89 size_t n;
90
91 *size = ext2_acl_size(acl->a_count);
92 ext_acl = (ext2_acl_header *)kmalloc(sizeof(ext2_acl_header) +
93 acl->a_count * sizeof(ext2_acl_entry), GFP_KERNEL);
94 if (!ext_acl)
95 return ERR_PTR(-ENOMEM);
96 ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
97 e = (char *)ext_acl + sizeof(ext2_acl_header);
98 for (n=0; n < acl->a_count; n++) {
99 ext2_acl_entry *entry = (ext2_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(ext2_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(ext2_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 ext2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
130 {
131 struct posix_acl *acl = EXT2_ACL_NOT_CACHED;
132
133 spin_lock(&inode->i_lock);
134 if (*i_acl != EXT2_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 ext2_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 != EXT2_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->i_mutex: don't care
154 */
155 static struct posix_acl *
156 ext2_get_acl(struct inode *inode, int type)
157 {
158 struct ext2_inode_info *ei = EXT2_I(inode);
159 int name_index;
160 char *value = NULL;
161 struct posix_acl *acl;
162 int retval;
163
164 if (!test_opt(inode->i_sb, POSIX_ACL))
165 return NULL;
166
167 switch(type) {
168 case ACL_TYPE_ACCESS:
169 acl = ext2_iget_acl(inode, &ei->i_acl);
170 if (acl != EXT2_ACL_NOT_CACHED)
171 return acl;
172 name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
173 break;
174
175 case ACL_TYPE_DEFAULT:
176 acl = ext2_iget_acl(inode, &ei->i_default_acl);
177 if (acl != EXT2_ACL_NOT_CACHED)
178 return acl;
179 name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
180 break;
181
182 default:
183 return ERR_PTR(-EINVAL);
184 }
185 retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
186 if (retval > 0) {
187 value = kmalloc(retval, GFP_KERNEL);
188 if (!value)
189 return ERR_PTR(-ENOMEM);
190 retval = ext2_xattr_get(inode, name_index, "", value, retval);
191 }
192 if (retval > 0)
193 acl = ext2_acl_from_disk(value, retval);
194 else if (retval == -ENODATA || retval == -ENOSYS)
195 acl = NULL;
196 else
197 acl = ERR_PTR(retval);
198 kfree(value);
199
200 if (!IS_ERR(acl)) {
201 switch(type) {
202 case ACL_TYPE_ACCESS:
203 ext2_iset_acl(inode, &ei->i_acl, acl);
204 break;
205
206 case ACL_TYPE_DEFAULT:
207 ext2_iset_acl(inode, &ei->i_default_acl, acl);
208 break;
209 }
210 }
211 return acl;
212 }
213
214 /*
215 * inode->i_mutex: down
216 */
217 static int
218 ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
219 {
220 struct ext2_inode_info *ei = EXT2_I(inode);
221 int name_index;
222 void *value = NULL;
223 size_t size = 0;
224 int error;
225
226 if (S_ISLNK(inode->i_mode))
227 return -EOPNOTSUPP;
228 if (!test_opt(inode->i_sb, POSIX_ACL))
229 return 0;
230
231 switch(type) {
232 case ACL_TYPE_ACCESS:
233 name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
234 if (acl) {
235 mode_t mode = inode->i_mode;
236 error = posix_acl_equiv_mode(acl, &mode);
237 if (error < 0)
238 return error;
239 else {
240 inode->i_mode = mode;
241 mark_inode_dirty(inode);
242 if (error == 0)
243 acl = NULL;
244 }
245 }
246 break;
247
248 case ACL_TYPE_DEFAULT:
249 name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
250 if (!S_ISDIR(inode->i_mode))
251 return acl ? -EACCES : 0;
252 break;
253
254 default:
255 return -EINVAL;
256 }
257 if (acl) {
258 value = ext2_acl_to_disk(acl, &size);
259 if (IS_ERR(value))
260 return (int)PTR_ERR(value);
261 }
262
263 error = ext2_xattr_set(inode, name_index, "", value, size, 0);
264
265 kfree(value);
266 if (!error) {
267 switch(type) {
268 case ACL_TYPE_ACCESS:
269 ext2_iset_acl(inode, &ei->i_acl, acl);
270 break;
271
272 case ACL_TYPE_DEFAULT:
273 ext2_iset_acl(inode, &ei->i_default_acl, acl);
274 break;
275 }
276 }
277 return error;
278 }
279
280 static int
281 ext2_check_acl(struct inode *inode, int mask)
282 {
283 struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
284
285 if (IS_ERR(acl))
286 return PTR_ERR(acl);
287 if (acl) {
288 int error = posix_acl_permission(inode, acl, mask);
289 posix_acl_release(acl);
290 return error;
291 }
292
293 return -EAGAIN;
294 }
295
296 int
297 ext2_permission(struct inode *inode, int mask, struct nameidata *nd)
298 {
299 return generic_permission(inode, mask, ext2_check_acl);
300 }
301
302 /*
303 * Initialize the ACLs of a new inode. Called from ext2_new_inode.
304 *
305 * dir->i_mutex: down
306 * inode->i_mutex: up (access to inode is still exclusive)
307 */
308 int
309 ext2_init_acl(struct inode *inode, struct inode *dir)
310 {
311 struct posix_acl *acl = NULL;
312 int error = 0;
313
314 if (!S_ISLNK(inode->i_mode)) {
315 if (test_opt(dir->i_sb, POSIX_ACL)) {
316 acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
317 if (IS_ERR(acl))
318 return PTR_ERR(acl);
319 }
320 if (!acl)
321 inode->i_mode &= ~current->fs->umask;
322 }
323 if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
324 struct posix_acl *clone;
325 mode_t mode;
326
327 if (S_ISDIR(inode->i_mode)) {
328 error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
329 if (error)
330 goto cleanup;
331 }
332 clone = posix_acl_clone(acl, GFP_KERNEL);
333 error = -ENOMEM;
334 if (!clone)
335 goto cleanup;
336 mode = inode->i_mode;
337 error = posix_acl_create_masq(clone, &mode);
338 if (error >= 0) {
339 inode->i_mode = mode;
340 if (error > 0) {
341 /* This is an extended ACL */
342 error = ext2_set_acl(inode,
343 ACL_TYPE_ACCESS, clone);
344 }
345 }
346 posix_acl_release(clone);
347 }
348 cleanup:
349 posix_acl_release(acl);
350 return error;
351 }
352
353 /*
354 * Does chmod for an inode that may have an Access Control List. The
355 * inode->i_mode field must be updated to the desired value by the caller
356 * before calling this function.
357 * Returns 0 on success, or a negative error number.
358 *
359 * We change the ACL rather than storing some ACL entries in the file
360 * mode permission bits (which would be more efficient), because that
361 * would break once additional permissions (like ACL_APPEND, ACL_DELETE
362 * for directories) are added. There are no more bits available in the
363 * file mode.
364 *
365 * inode->i_mutex: down
366 */
367 int
368 ext2_acl_chmod(struct inode *inode)
369 {
370 struct posix_acl *acl, *clone;
371 int error;
372
373 if (!test_opt(inode->i_sb, POSIX_ACL))
374 return 0;
375 if (S_ISLNK(inode->i_mode))
376 return -EOPNOTSUPP;
377 acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
378 if (IS_ERR(acl) || !acl)
379 return PTR_ERR(acl);
380 clone = posix_acl_clone(acl, GFP_KERNEL);
381 posix_acl_release(acl);
382 if (!clone)
383 return -ENOMEM;
384 error = posix_acl_chmod_masq(clone, inode->i_mode);
385 if (!error)
386 error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
387 posix_acl_release(clone);
388 return error;
389 }
390
391 /*
392 * Extended attribut handlers
393 */
394 static size_t
395 ext2_xattr_list_acl_access(struct inode *inode, char *list, size_t list_size,
396 const char *name, size_t name_len)
397 {
398 const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
399
400 if (!test_opt(inode->i_sb, POSIX_ACL))
401 return 0;
402 if (list && size <= list_size)
403 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
404 return size;
405 }
406
407 static size_t
408 ext2_xattr_list_acl_default(struct inode *inode, char *list, size_t list_size,
409 const char *name, size_t name_len)
410 {
411 const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
412
413 if (!test_opt(inode->i_sb, POSIX_ACL))
414 return 0;
415 if (list && size <= list_size)
416 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
417 return size;
418 }
419
420 static int
421 ext2_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
422 {
423 struct posix_acl *acl;
424 int error;
425
426 if (!test_opt(inode->i_sb, POSIX_ACL))
427 return -EOPNOTSUPP;
428
429 acl = ext2_get_acl(inode, type);
430 if (IS_ERR(acl))
431 return PTR_ERR(acl);
432 if (acl == NULL)
433 return -ENODATA;
434 error = posix_acl_to_xattr(acl, buffer, size);
435 posix_acl_release(acl);
436
437 return error;
438 }
439
440 static int
441 ext2_xattr_get_acl_access(struct inode *inode, const char *name,
442 void *buffer, size_t size)
443 {
444 if (strcmp(name, "") != 0)
445 return -EINVAL;
446 return ext2_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
447 }
448
449 static int
450 ext2_xattr_get_acl_default(struct inode *inode, const char *name,
451 void *buffer, size_t size)
452 {
453 if (strcmp(name, "") != 0)
454 return -EINVAL;
455 return ext2_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
456 }
457
458 static int
459 ext2_xattr_set_acl(struct inode *inode, int type, const void *value,
460 size_t size)
461 {
462 struct posix_acl *acl;
463 int error;
464
465 if (!test_opt(inode->i_sb, POSIX_ACL))
466 return -EOPNOTSUPP;
467 if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
468 return -EPERM;
469
470 if (value) {
471 acl = posix_acl_from_xattr(value, size);
472 if (IS_ERR(acl))
473 return PTR_ERR(acl);
474 else if (acl) {
475 error = posix_acl_valid(acl);
476 if (error)
477 goto release_and_out;
478 }
479 } else
480 acl = NULL;
481
482 error = ext2_set_acl(inode, type, acl);
483
484 release_and_out:
485 posix_acl_release(acl);
486 return error;
487 }
488
489 static int
490 ext2_xattr_set_acl_access(struct inode *inode, const char *name,
491 const void *value, size_t size, int flags)
492 {
493 if (strcmp(name, "") != 0)
494 return -EINVAL;
495 return ext2_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
496 }
497
498 static int
499 ext2_xattr_set_acl_default(struct inode *inode, const char *name,
500 const void *value, size_t size, int flags)
501 {
502 if (strcmp(name, "") != 0)
503 return -EINVAL;
504 return ext2_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
505 }
506
507 struct xattr_handler ext2_xattr_acl_access_handler = {
508 .prefix = POSIX_ACL_XATTR_ACCESS,
509 .list = ext2_xattr_list_acl_access,
510 .get = ext2_xattr_get_acl_access,
511 .set = ext2_xattr_set_acl_access,
512 };
513
514 struct xattr_handler ext2_xattr_acl_default_handler = {
515 .prefix = POSIX_ACL_XATTR_DEFAULT,
516 .list = ext2_xattr_list_acl_default,
517 .get = ext2_xattr_get_acl_default,
518 .set = ext2_xattr_set_acl_default,
519 };
520
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