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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 | /* |
130 | * Inode operation get_posix_acl(). |
131 | * |
132 | * inode->i_mutex: don't care |
133 | */ |
134 | static struct posix_acl * |
135 | ext4_get_acl(struct inode *inode, int type) |
136 | { |
137 | int name_index; |
138 | char *value = NULL; |
139 | struct posix_acl *acl; |
140 | int retval; |
141 | |
142 | if (!test_opt(inode->i_sb, POSIX_ACL)) |
143 | return NULL; |
144 | |
145 | acl = get_cached_acl(inode, type); |
146 | if (acl != ACL_NOT_CACHED) |
147 | return acl; |
148 | |
149 | switch (type) { |
150 | case ACL_TYPE_ACCESS: |
151 | name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; |
152 | break; |
153 | case ACL_TYPE_DEFAULT: |
154 | name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; |
155 | break; |
156 | default: |
157 | BUG(); |
158 | } |
159 | retval = ext4_xattr_get(inode, name_index, "", NULL, 0); |
160 | if (retval > 0) { |
161 | value = kmalloc(retval, GFP_NOFS); |
162 | if (!value) |
163 | return ERR_PTR(-ENOMEM); |
164 | retval = ext4_xattr_get(inode, name_index, "", value, retval); |
165 | } |
166 | if (retval > 0) |
167 | acl = ext4_acl_from_disk(value, retval); |
168 | else if (retval == -ENODATA || retval == -ENOSYS) |
169 | acl = NULL; |
170 | else |
171 | acl = ERR_PTR(retval); |
172 | kfree(value); |
173 | |
174 | if (!IS_ERR(acl)) |
175 | set_cached_acl(inode, type, acl); |
176 | |
177 | return acl; |
178 | } |
179 | |
180 | /* |
181 | * Set the access or default ACL of an inode. |
182 | * |
183 | * inode->i_mutex: down unless called from ext4_new_inode |
184 | */ |
185 | static int |
186 | ext4_set_acl(handle_t *handle, struct inode *inode, int type, |
187 | struct posix_acl *acl) |
188 | { |
189 | int name_index; |
190 | void *value = NULL; |
191 | size_t size = 0; |
192 | int error; |
193 | |
194 | if (S_ISLNK(inode->i_mode)) |
195 | return -EOPNOTSUPP; |
196 | |
197 | switch (type) { |
198 | case ACL_TYPE_ACCESS: |
199 | name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; |
200 | if (acl) { |
201 | mode_t mode = inode->i_mode; |
202 | error = posix_acl_equiv_mode(acl, &mode); |
203 | if (error < 0) |
204 | return error; |
205 | else { |
206 | inode->i_mode = mode; |
207 | ext4_mark_inode_dirty(handle, inode); |
208 | if (error == 0) |
209 | acl = NULL; |
210 | } |
211 | } |
212 | break; |
213 | |
214 | case ACL_TYPE_DEFAULT: |
215 | name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT; |
216 | if (!S_ISDIR(inode->i_mode)) |
217 | return acl ? -EACCES : 0; |
218 | break; |
219 | |
220 | default: |
221 | return -EINVAL; |
222 | } |
223 | if (acl) { |
224 | value = ext4_acl_to_disk(acl, &size); |
225 | if (IS_ERR(value)) |
226 | return (int)PTR_ERR(value); |
227 | } |
228 | |
229 | error = ext4_xattr_set_handle(handle, inode, name_index, "", |
230 | value, size, 0); |
231 | |
232 | kfree(value); |
233 | if (!error) |
234 | set_cached_acl(inode, type, acl); |
235 | |
236 | return error; |
237 | } |
238 | |
239 | static int |
240 | ext4_check_acl(struct inode *inode, int mask) |
241 | { |
242 | struct posix_acl *acl = ext4_get_acl(inode, ACL_TYPE_ACCESS); |
243 | |
244 | if (IS_ERR(acl)) |
245 | return PTR_ERR(acl); |
246 | if (acl) { |
247 | int error = posix_acl_permission(inode, acl, mask); |
248 | posix_acl_release(acl); |
249 | return error; |
250 | } |
251 | |
252 | return -EAGAIN; |
253 | } |
254 | |
255 | int |
256 | ext4_permission(struct inode *inode, int mask) |
257 | { |
258 | return generic_permission(inode, mask, ext4_check_acl); |
259 | } |
260 | |
261 | /* |
262 | * Initialize the ACLs of a new inode. Called from ext4_new_inode. |
263 | * |
264 | * dir->i_mutex: down |
265 | * inode->i_mutex: up (access to inode is still exclusive) |
266 | */ |
267 | int |
268 | ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir) |
269 | { |
270 | struct posix_acl *acl = NULL; |
271 | int error = 0; |
272 | |
273 | if (!S_ISLNK(inode->i_mode)) { |
274 | if (test_opt(dir->i_sb, POSIX_ACL)) { |
275 | acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT); |
276 | if (IS_ERR(acl)) |
277 | return PTR_ERR(acl); |
278 | } |
279 | if (!acl) |
280 | inode->i_mode &= ~current_umask(); |
281 | } |
282 | if (test_opt(inode->i_sb, POSIX_ACL) && acl) { |
283 | struct posix_acl *clone; |
284 | mode_t mode; |
285 | |
286 | if (S_ISDIR(inode->i_mode)) { |
287 | error = ext4_set_acl(handle, inode, |
288 | ACL_TYPE_DEFAULT, acl); |
289 | if (error) |
290 | goto cleanup; |
291 | } |
292 | clone = posix_acl_clone(acl, GFP_NOFS); |
293 | error = -ENOMEM; |
294 | if (!clone) |
295 | goto cleanup; |
296 | |
297 | mode = inode->i_mode; |
298 | error = posix_acl_create_masq(clone, &mode); |
299 | if (error >= 0) { |
300 | inode->i_mode = mode; |
301 | if (error > 0) { |
302 | /* This is an extended ACL */ |
303 | error = ext4_set_acl(handle, inode, |
304 | ACL_TYPE_ACCESS, clone); |
305 | } |
306 | } |
307 | posix_acl_release(clone); |
308 | } |
309 | cleanup: |
310 | posix_acl_release(acl); |
311 | return error; |
312 | } |
313 | |
314 | /* |
315 | * Does chmod for an inode that may have an Access Control List. The |
316 | * inode->i_mode field must be updated to the desired value by the caller |
317 | * before calling this function. |
318 | * Returns 0 on success, or a negative error number. |
319 | * |
320 | * We change the ACL rather than storing some ACL entries in the file |
321 | * mode permission bits (which would be more efficient), because that |
322 | * would break once additional permissions (like ACL_APPEND, ACL_DELETE |
323 | * for directories) are added. There are no more bits available in the |
324 | * file mode. |
325 | * |
326 | * inode->i_mutex: down |
327 | */ |
328 | int |
329 | ext4_acl_chmod(struct inode *inode) |
330 | { |
331 | struct posix_acl *acl, *clone; |
332 | int error; |
333 | |
334 | if (S_ISLNK(inode->i_mode)) |
335 | return -EOPNOTSUPP; |
336 | if (!test_opt(inode->i_sb, POSIX_ACL)) |
337 | return 0; |
338 | acl = ext4_get_acl(inode, ACL_TYPE_ACCESS); |
339 | if (IS_ERR(acl) || !acl) |
340 | return PTR_ERR(acl); |
341 | clone = posix_acl_clone(acl, GFP_KERNEL); |
342 | posix_acl_release(acl); |
343 | if (!clone) |
344 | return -ENOMEM; |
345 | error = posix_acl_chmod_masq(clone, inode->i_mode); |
346 | if (!error) { |
347 | handle_t *handle; |
348 | int retries = 0; |
349 | |
350 | retry: |
351 | handle = ext4_journal_start(inode, |
352 | EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); |
353 | if (IS_ERR(handle)) { |
354 | error = PTR_ERR(handle); |
355 | ext4_std_error(inode->i_sb, error); |
356 | goto out; |
357 | } |
358 | error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, clone); |
359 | ext4_journal_stop(handle); |
360 | if (error == -ENOSPC && |
361 | ext4_should_retry_alloc(inode->i_sb, &retries)) |
362 | goto retry; |
363 | } |
364 | out: |
365 | posix_acl_release(clone); |
366 | return error; |
367 | } |
368 | |
369 | /* |
370 | * Extended attribute handlers |
371 | */ |
372 | static size_t |
373 | ext4_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len, |
374 | const char *name, size_t name_len) |
375 | { |
376 | const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS); |
377 | |
378 | if (!test_opt(inode->i_sb, POSIX_ACL)) |
379 | return 0; |
380 | if (list && size <= list_len) |
381 | memcpy(list, POSIX_ACL_XATTR_ACCESS, size); |
382 | return size; |
383 | } |
384 | |
385 | static size_t |
386 | ext4_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len, |
387 | const char *name, size_t name_len) |
388 | { |
389 | const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT); |
390 | |
391 | if (!test_opt(inode->i_sb, POSIX_ACL)) |
392 | return 0; |
393 | if (list && size <= list_len) |
394 | memcpy(list, POSIX_ACL_XATTR_DEFAULT, size); |
395 | return size; |
396 | } |
397 | |
398 | static int |
399 | ext4_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size) |
400 | { |
401 | struct posix_acl *acl; |
402 | int error; |
403 | |
404 | if (!test_opt(inode->i_sb, POSIX_ACL)) |
405 | return -EOPNOTSUPP; |
406 | |
407 | acl = ext4_get_acl(inode, type); |
408 | if (IS_ERR(acl)) |
409 | return PTR_ERR(acl); |
410 | if (acl == NULL) |
411 | return -ENODATA; |
412 | error = posix_acl_to_xattr(acl, buffer, size); |
413 | posix_acl_release(acl); |
414 | |
415 | return error; |
416 | } |
417 | |
418 | static int |
419 | ext4_xattr_get_acl_access(struct inode *inode, const char *name, |
420 | void *buffer, size_t size) |
421 | { |
422 | if (strcmp(name, "") != 0) |
423 | return -EINVAL; |
424 | return ext4_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size); |
425 | } |
426 | |
427 | static int |
428 | ext4_xattr_get_acl_default(struct inode *inode, const char *name, |
429 | void *buffer, size_t size) |
430 | { |
431 | if (strcmp(name, "") != 0) |
432 | return -EINVAL; |
433 | return ext4_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size); |
434 | } |
435 | |
436 | static int |
437 | ext4_xattr_set_acl(struct inode *inode, int type, const void *value, |
438 | size_t size) |
439 | { |
440 | handle_t *handle; |
441 | struct posix_acl *acl; |
442 | int error, retries = 0; |
443 | |
444 | if (!test_opt(inode->i_sb, POSIX_ACL)) |
445 | return -EOPNOTSUPP; |
446 | if (!is_owner_or_cap(inode)) |
447 | return -EPERM; |
448 | |
449 | if (value) { |
450 | acl = posix_acl_from_xattr(value, size); |
451 | if (IS_ERR(acl)) |
452 | return PTR_ERR(acl); |
453 | else if (acl) { |
454 | error = posix_acl_valid(acl); |
455 | if (error) |
456 | goto release_and_out; |
457 | } |
458 | } else |
459 | acl = NULL; |
460 | |
461 | retry: |
462 | handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb)); |
463 | if (IS_ERR(handle)) |
464 | return PTR_ERR(handle); |
465 | error = ext4_set_acl(handle, inode, type, acl); |
466 | ext4_journal_stop(handle); |
467 | if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) |
468 | goto retry; |
469 | |
470 | release_and_out: |
471 | posix_acl_release(acl); |
472 | return error; |
473 | } |
474 | |
475 | static int |
476 | ext4_xattr_set_acl_access(struct inode *inode, const char *name, |
477 | const void *value, size_t size, int flags) |
478 | { |
479 | if (strcmp(name, "") != 0) |
480 | return -EINVAL; |
481 | return ext4_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size); |
482 | } |
483 | |
484 | static int |
485 | ext4_xattr_set_acl_default(struct inode *inode, const char *name, |
486 | const void *value, size_t size, int flags) |
487 | { |
488 | if (strcmp(name, "") != 0) |
489 | return -EINVAL; |
490 | return ext4_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size); |
491 | } |
492 | |
493 | struct xattr_handler ext4_xattr_acl_access_handler = { |
494 | .prefix = POSIX_ACL_XATTR_ACCESS, |
495 | .list = ext4_xattr_list_acl_access, |
496 | .get = ext4_xattr_get_acl_access, |
497 | .set = ext4_xattr_set_acl_access, |
498 | }; |
499 | |
500 | struct xattr_handler ext4_xattr_acl_default_handler = { |
501 | .prefix = POSIX_ACL_XATTR_DEFAULT, |
502 | .list = ext4_xattr_list_acl_default, |
503 | .get = ext4_xattr_get_acl_default, |
504 | .set = ext4_xattr_set_acl_default, |
505 | }; |
506 |
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