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ef14f0c1 CH |
1 | /* |
2 | * Copyright (c) 2008, Christoph Hellwig | |
3 | * All Rights Reserved. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or | |
6 | * modify it under the terms of the GNU General Public License as | |
7 | * published by the Free Software Foundation. | |
8 | * | |
9 | * This program is distributed in the hope that it would be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write the Free Software Foundation, | |
16 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
17 | */ | |
18 | #include "xfs.h" | |
19 | #include "xfs_acl.h" | |
20 | #include "xfs_attr.h" | |
21 | #include "xfs_bmap_btree.h" | |
22 | #include "xfs_inode.h" | |
23 | #include "xfs_vnodeops.h" | |
24 | #include <linux/xattr.h> | |
25 | #include <linux/posix_acl_xattr.h> | |
26 | ||
27 | ||
28 | #define XFS_ACL_NOT_CACHED ((void *)-1) | |
29 | ||
30 | /* | |
31 | * Locking scheme: | |
32 | * - all ACL updates are protected by inode->i_mutex, which is taken before | |
33 | * calling into this file. | |
34 | * - access and updates to the ip->i_acl and ip->i_default_acl pointers are | |
35 | * protected by inode->i_lock. | |
36 | */ | |
37 | ||
38 | STATIC struct posix_acl * | |
39 | xfs_acl_from_disk(struct xfs_acl *aclp) | |
40 | { | |
41 | struct posix_acl_entry *acl_e; | |
42 | struct posix_acl *acl; | |
43 | struct xfs_acl_entry *ace; | |
44 | int count, i; | |
45 | ||
46 | count = be32_to_cpu(aclp->acl_cnt); | |
47 | ||
48 | acl = posix_acl_alloc(count, GFP_KERNEL); | |
49 | if (!acl) | |
50 | return ERR_PTR(-ENOMEM); | |
51 | ||
52 | for (i = 0; i < count; i++) { | |
53 | acl_e = &acl->a_entries[i]; | |
54 | ace = &aclp->acl_entry[i]; | |
55 | ||
56 | /* | |
57 | * The tag is 32 bits on disk and 16 bits in core. | |
58 | * | |
59 | * Because every access to it goes through the core | |
60 | * format first this is not a problem. | |
61 | */ | |
62 | acl_e->e_tag = be32_to_cpu(ace->ae_tag); | |
63 | acl_e->e_perm = be16_to_cpu(ace->ae_perm); | |
64 | ||
65 | switch (acl_e->e_tag) { | |
66 | case ACL_USER: | |
67 | case ACL_GROUP: | |
68 | acl_e->e_id = be32_to_cpu(ace->ae_id); | |
69 | break; | |
70 | case ACL_USER_OBJ: | |
71 | case ACL_GROUP_OBJ: | |
72 | case ACL_MASK: | |
73 | case ACL_OTHER: | |
74 | acl_e->e_id = ACL_UNDEFINED_ID; | |
75 | break; | |
76 | default: | |
77 | goto fail; | |
78 | } | |
79 | } | |
80 | return acl; | |
81 | ||
82 | fail: | |
83 | posix_acl_release(acl); | |
84 | return ERR_PTR(-EINVAL); | |
85 | } | |
86 | ||
87 | STATIC void | |
88 | xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl) | |
89 | { | |
90 | const struct posix_acl_entry *acl_e; | |
91 | struct xfs_acl_entry *ace; | |
92 | int i; | |
93 | ||
94 | aclp->acl_cnt = cpu_to_be32(acl->a_count); | |
95 | for (i = 0; i < acl->a_count; i++) { | |
96 | ace = &aclp->acl_entry[i]; | |
97 | acl_e = &acl->a_entries[i]; | |
98 | ||
99 | ace->ae_tag = cpu_to_be32(acl_e->e_tag); | |
100 | ace->ae_id = cpu_to_be32(acl_e->e_id); | |
101 | ace->ae_perm = cpu_to_be16(acl_e->e_perm); | |
102 | } | |
103 | } | |
104 | ||
105 | /* | |
106 | * Update the cached ACL pointer in the inode. | |
107 | * | |
108 | * Because we don't hold any locks while reading/writing the attribute | |
109 | * from/to disk another thread could have raced and updated the cached | |
110 | * ACL value before us. In that case we release the previous cached value | |
111 | * and update it with our new value. | |
112 | */ | |
113 | STATIC void | |
114 | xfs_update_cached_acl(struct inode *inode, struct posix_acl **p_acl, | |
115 | struct posix_acl *acl) | |
116 | { | |
117 | spin_lock(&inode->i_lock); | |
118 | if (*p_acl && *p_acl != XFS_ACL_NOT_CACHED) | |
119 | posix_acl_release(*p_acl); | |
120 | *p_acl = posix_acl_dup(acl); | |
121 | spin_unlock(&inode->i_lock); | |
122 | } | |
123 | ||
124 | struct posix_acl * | |
125 | xfs_get_acl(struct inode *inode, int type) | |
126 | { | |
127 | struct xfs_inode *ip = XFS_I(inode); | |
128 | struct posix_acl *acl = NULL, **p_acl; | |
129 | struct xfs_acl *xfs_acl; | |
130 | int len = sizeof(struct xfs_acl); | |
131 | char *ea_name; | |
132 | int error; | |
133 | ||
134 | switch (type) { | |
135 | case ACL_TYPE_ACCESS: | |
136 | ea_name = SGI_ACL_FILE; | |
137 | p_acl = &ip->i_acl; | |
138 | break; | |
139 | case ACL_TYPE_DEFAULT: | |
140 | ea_name = SGI_ACL_DEFAULT; | |
141 | p_acl = &ip->i_default_acl; | |
142 | break; | |
143 | default: | |
144 | return ERR_PTR(-EINVAL); | |
145 | } | |
146 | ||
147 | spin_lock(&inode->i_lock); | |
148 | if (*p_acl != XFS_ACL_NOT_CACHED) | |
149 | acl = posix_acl_dup(*p_acl); | |
150 | spin_unlock(&inode->i_lock); | |
151 | ||
152 | /* | |
153 | * If we have a cached ACLs value just return it, not need to | |
154 | * go out to the disk. | |
155 | */ | |
156 | if (acl) | |
157 | return acl; | |
158 | ||
159 | xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL); | |
160 | if (!xfs_acl) | |
161 | return ERR_PTR(-ENOMEM); | |
162 | ||
163 | error = -xfs_attr_get(ip, ea_name, (char *)xfs_acl, &len, ATTR_ROOT); | |
164 | if (error) { | |
165 | /* | |
166 | * If the attribute doesn't exist make sure we have a negative | |
167 | * cache entry, for any other error assume it is transient and | |
168 | * leave the cache entry as XFS_ACL_NOT_CACHED. | |
169 | */ | |
170 | if (error == -ENOATTR) { | |
171 | acl = NULL; | |
172 | goto out_update_cache; | |
173 | } | |
174 | goto out; | |
175 | } | |
176 | ||
177 | acl = xfs_acl_from_disk(xfs_acl); | |
178 | if (IS_ERR(acl)) | |
179 | goto out; | |
180 | ||
181 | out_update_cache: | |
182 | xfs_update_cached_acl(inode, p_acl, acl); | |
183 | out: | |
184 | kfree(xfs_acl); | |
185 | return acl; | |
186 | } | |
187 | ||
188 | STATIC int | |
189 | xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl) | |
190 | { | |
191 | struct xfs_inode *ip = XFS_I(inode); | |
192 | struct posix_acl **p_acl; | |
193 | char *ea_name; | |
194 | int error; | |
195 | ||
196 | if (S_ISLNK(inode->i_mode)) | |
197 | return -EOPNOTSUPP; | |
198 | ||
199 | switch (type) { | |
200 | case ACL_TYPE_ACCESS: | |
201 | ea_name = SGI_ACL_FILE; | |
202 | p_acl = &ip->i_acl; | |
203 | break; | |
204 | case ACL_TYPE_DEFAULT: | |
205 | if (!S_ISDIR(inode->i_mode)) | |
206 | return acl ? -EACCES : 0; | |
207 | ea_name = SGI_ACL_DEFAULT; | |
208 | p_acl = &ip->i_default_acl; | |
209 | break; | |
210 | default: | |
211 | return -EINVAL; | |
212 | } | |
213 | ||
214 | if (acl) { | |
215 | struct xfs_acl *xfs_acl; | |
216 | int len; | |
217 | ||
218 | xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL); | |
219 | if (!xfs_acl) | |
220 | return -ENOMEM; | |
221 | ||
222 | xfs_acl_to_disk(xfs_acl, acl); | |
223 | len = sizeof(struct xfs_acl) - | |
224 | (sizeof(struct xfs_acl_entry) * | |
225 | (XFS_ACL_MAX_ENTRIES - acl->a_count)); | |
226 | ||
227 | error = -xfs_attr_set(ip, ea_name, (char *)xfs_acl, | |
228 | len, ATTR_ROOT); | |
229 | ||
230 | kfree(xfs_acl); | |
231 | } else { | |
232 | /* | |
233 | * A NULL ACL argument means we want to remove the ACL. | |
234 | */ | |
235 | error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT); | |
236 | ||
237 | /* | |
238 | * If the attribute didn't exist to start with that's fine. | |
239 | */ | |
240 | if (error == -ENOATTR) | |
241 | error = 0; | |
242 | } | |
243 | ||
244 | if (!error) | |
245 | xfs_update_cached_acl(inode, p_acl, acl); | |
246 | return error; | |
247 | } | |
248 | ||
249 | int | |
250 | xfs_check_acl(struct inode *inode, int mask) | |
251 | { | |
252 | struct xfs_inode *ip = XFS_I(inode); | |
253 | struct posix_acl *acl; | |
254 | int error = -EAGAIN; | |
255 | ||
256 | xfs_itrace_entry(ip); | |
257 | ||
258 | /* | |
259 | * If there is no attribute fork no ACL exists on this inode and | |
260 | * we can skip the whole exercise. | |
261 | */ | |
262 | if (!XFS_IFORK_Q(ip)) | |
263 | return -EAGAIN; | |
264 | ||
265 | acl = xfs_get_acl(inode, ACL_TYPE_ACCESS); | |
266 | if (IS_ERR(acl)) | |
267 | return PTR_ERR(acl); | |
268 | if (acl) { | |
269 | error = posix_acl_permission(inode, acl, mask); | |
270 | posix_acl_release(acl); | |
271 | } | |
272 | ||
273 | return error; | |
274 | } | |
275 | ||
276 | static int | |
277 | xfs_set_mode(struct inode *inode, mode_t mode) | |
278 | { | |
279 | int error = 0; | |
280 | ||
281 | if (mode != inode->i_mode) { | |
282 | struct iattr iattr; | |
283 | ||
284 | iattr.ia_valid = ATTR_MODE; | |
285 | iattr.ia_mode = mode; | |
286 | ||
287 | error = -xfs_setattr(XFS_I(inode), &iattr, XFS_ATTR_NOACL); | |
288 | } | |
289 | ||
290 | return error; | |
291 | } | |
292 | ||
293 | static int | |
294 | xfs_acl_exists(struct inode *inode, char *name) | |
295 | { | |
296 | int len = sizeof(struct xfs_acl); | |
297 | ||
298 | return (xfs_attr_get(XFS_I(inode), name, NULL, &len, | |
299 | ATTR_ROOT|ATTR_KERNOVAL) == 0); | |
300 | } | |
301 | ||
302 | int | |
303 | posix_acl_access_exists(struct inode *inode) | |
304 | { | |
305 | return xfs_acl_exists(inode, SGI_ACL_FILE); | |
306 | } | |
307 | ||
308 | int | |
309 | posix_acl_default_exists(struct inode *inode) | |
310 | { | |
311 | if (!S_ISDIR(inode->i_mode)) | |
312 | return 0; | |
313 | return xfs_acl_exists(inode, SGI_ACL_DEFAULT); | |
314 | } | |
315 | ||
316 | /* | |
317 | * No need for i_mutex because the inode is not yet exposed to the VFS. | |
318 | */ | |
319 | int | |
320 | xfs_inherit_acl(struct inode *inode, struct posix_acl *default_acl) | |
321 | { | |
322 | struct posix_acl *clone; | |
323 | mode_t mode; | |
324 | int error = 0, inherit = 0; | |
325 | ||
326 | if (S_ISDIR(inode->i_mode)) { | |
327 | error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl); | |
328 | if (error) | |
329 | return error; | |
330 | } | |
331 | ||
332 | clone = posix_acl_clone(default_acl, GFP_KERNEL); | |
333 | if (!clone) | |
334 | return -ENOMEM; | |
335 | ||
336 | mode = inode->i_mode; | |
337 | error = posix_acl_create_masq(clone, &mode); | |
338 | if (error < 0) | |
339 | goto out_release_clone; | |
340 | ||
341 | /* | |
342 | * If posix_acl_create_masq returns a positive value we need to | |
343 | * inherit a permission that can't be represented using the Unix | |
344 | * mode bits and we actually need to set an ACL. | |
345 | */ | |
346 | if (error > 0) | |
347 | inherit = 1; | |
348 | ||
349 | error = xfs_set_mode(inode, mode); | |
350 | if (error) | |
351 | goto out_release_clone; | |
352 | ||
353 | if (inherit) | |
354 | error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone); | |
355 | ||
356 | out_release_clone: | |
357 | posix_acl_release(clone); | |
358 | return error; | |
359 | } | |
360 | ||
361 | int | |
362 | xfs_acl_chmod(struct inode *inode) | |
363 | { | |
364 | struct posix_acl *acl, *clone; | |
365 | int error; | |
366 | ||
367 | if (S_ISLNK(inode->i_mode)) | |
368 | return -EOPNOTSUPP; | |
369 | ||
370 | acl = xfs_get_acl(inode, ACL_TYPE_ACCESS); | |
371 | if (IS_ERR(acl) || !acl) | |
372 | return PTR_ERR(acl); | |
373 | ||
374 | clone = posix_acl_clone(acl, GFP_KERNEL); | |
375 | posix_acl_release(acl); | |
376 | if (!clone) | |
377 | return -ENOMEM; | |
378 | ||
379 | error = posix_acl_chmod_masq(clone, inode->i_mode); | |
380 | if (!error) | |
381 | error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone); | |
382 | ||
383 | posix_acl_release(clone); | |
384 | return error; | |
385 | } | |
386 | ||
387 | void | |
388 | xfs_inode_init_acls(struct xfs_inode *ip) | |
389 | { | |
390 | /* | |
391 | * No need for locking, inode is not live yet. | |
392 | */ | |
393 | ip->i_acl = XFS_ACL_NOT_CACHED; | |
394 | ip->i_default_acl = XFS_ACL_NOT_CACHED; | |
395 | } | |
396 | ||
397 | void | |
398 | xfs_inode_clear_acls(struct xfs_inode *ip) | |
399 | { | |
400 | /* | |
401 | * No need for locking here, the inode is not live anymore | |
402 | * and just about to be freed. | |
403 | */ | |
404 | if (ip->i_acl != XFS_ACL_NOT_CACHED) | |
405 | posix_acl_release(ip->i_acl); | |
406 | if (ip->i_default_acl != XFS_ACL_NOT_CACHED) | |
407 | posix_acl_release(ip->i_default_acl); | |
408 | } | |
409 | ||
410 | ||
411 | /* | |
412 | * System xattr handlers. | |
413 | * | |
414 | * Currently Posix ACLs are the only system namespace extended attribute | |
415 | * handlers supported by XFS, so we just implement the handlers here. | |
416 | * If we ever support other system extended attributes this will need | |
417 | * some refactoring. | |
418 | */ | |
419 | ||
420 | static int | |
421 | xfs_decode_acl(const char *name) | |
422 | { | |
423 | if (strcmp(name, "posix_acl_access") == 0) | |
424 | return ACL_TYPE_ACCESS; | |
425 | else if (strcmp(name, "posix_acl_default") == 0) | |
426 | return ACL_TYPE_DEFAULT; | |
427 | return -EINVAL; | |
428 | } | |
429 | ||
430 | static int | |
431 | xfs_xattr_system_get(struct inode *inode, const char *name, | |
432 | void *value, size_t size) | |
433 | { | |
434 | struct posix_acl *acl; | |
435 | int type, error; | |
436 | ||
437 | type = xfs_decode_acl(name); | |
438 | if (type < 0) | |
439 | return type; | |
440 | ||
441 | acl = xfs_get_acl(inode, type); | |
442 | if (IS_ERR(acl)) | |
443 | return PTR_ERR(acl); | |
444 | if (acl == NULL) | |
445 | return -ENODATA; | |
446 | ||
447 | error = posix_acl_to_xattr(acl, value, size); | |
448 | posix_acl_release(acl); | |
449 | ||
450 | return error; | |
451 | } | |
452 | ||
453 | static int | |
454 | xfs_xattr_system_set(struct inode *inode, const char *name, | |
455 | const void *value, size_t size, int flags) | |
456 | { | |
457 | struct posix_acl *acl = NULL; | |
458 | int error = 0, type; | |
459 | ||
460 | type = xfs_decode_acl(name); | |
461 | if (type < 0) | |
462 | return type; | |
463 | if (flags & XATTR_CREATE) | |
464 | return -EINVAL; | |
465 | if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) | |
466 | return value ? -EACCES : 0; | |
467 | if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER)) | |
468 | return -EPERM; | |
469 | ||
470 | if (!value) | |
471 | goto set_acl; | |
472 | ||
473 | acl = posix_acl_from_xattr(value, size); | |
474 | if (!acl) { | |
475 | /* | |
476 | * acl_set_file(3) may request that we set default ACLs with | |
477 | * zero length -- defend (gracefully) against that here. | |
478 | */ | |
479 | goto out; | |
480 | } | |
481 | if (IS_ERR(acl)) { | |
482 | error = PTR_ERR(acl); | |
483 | goto out; | |
484 | } | |
485 | ||
486 | error = posix_acl_valid(acl); | |
487 | if (error) | |
488 | goto out_release; | |
489 | ||
490 | error = -EINVAL; | |
491 | if (acl->a_count > XFS_ACL_MAX_ENTRIES) | |
492 | goto out_release; | |
493 | ||
494 | if (type == ACL_TYPE_ACCESS) { | |
495 | mode_t mode = inode->i_mode; | |
496 | error = posix_acl_equiv_mode(acl, &mode); | |
497 | ||
498 | if (error <= 0) { | |
499 | posix_acl_release(acl); | |
500 | acl = NULL; | |
501 | ||
502 | if (error < 0) | |
503 | return error; | |
504 | } | |
505 | ||
506 | error = xfs_set_mode(inode, mode); | |
507 | if (error) | |
508 | goto out_release; | |
509 | } | |
510 | ||
511 | set_acl: | |
512 | error = xfs_set_acl(inode, type, acl); | |
513 | out_release: | |
514 | posix_acl_release(acl); | |
515 | out: | |
516 | return error; | |
517 | } | |
518 | ||
519 | struct xattr_handler xfs_xattr_system_handler = { | |
520 | .prefix = XATTR_SYSTEM_PREFIX, | |
521 | .get = xfs_xattr_system_get, | |
522 | .set = xfs_xattr_system_set, | |
523 | }; |