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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 | ||
ef14f0c1 CH |
28 | /* |
29 | * Locking scheme: | |
30 | * - all ACL updates are protected by inode->i_mutex, which is taken before | |
31 | * calling into this file. | |
ef14f0c1 CH |
32 | */ |
33 | ||
34 | STATIC struct posix_acl * | |
35 | xfs_acl_from_disk(struct xfs_acl *aclp) | |
36 | { | |
37 | struct posix_acl_entry *acl_e; | |
38 | struct posix_acl *acl; | |
39 | struct xfs_acl_entry *ace; | |
40 | int count, i; | |
41 | ||
42 | count = be32_to_cpu(aclp->acl_cnt); | |
43 | ||
44 | acl = posix_acl_alloc(count, GFP_KERNEL); | |
45 | if (!acl) | |
46 | return ERR_PTR(-ENOMEM); | |
47 | ||
48 | for (i = 0; i < count; i++) { | |
49 | acl_e = &acl->a_entries[i]; | |
50 | ace = &aclp->acl_entry[i]; | |
51 | ||
52 | /* | |
53 | * The tag is 32 bits on disk and 16 bits in core. | |
54 | * | |
55 | * Because every access to it goes through the core | |
56 | * format first this is not a problem. | |
57 | */ | |
58 | acl_e->e_tag = be32_to_cpu(ace->ae_tag); | |
59 | acl_e->e_perm = be16_to_cpu(ace->ae_perm); | |
60 | ||
61 | switch (acl_e->e_tag) { | |
62 | case ACL_USER: | |
63 | case ACL_GROUP: | |
64 | acl_e->e_id = be32_to_cpu(ace->ae_id); | |
65 | break; | |
66 | case ACL_USER_OBJ: | |
67 | case ACL_GROUP_OBJ: | |
68 | case ACL_MASK: | |
69 | case ACL_OTHER: | |
70 | acl_e->e_id = ACL_UNDEFINED_ID; | |
71 | break; | |
72 | default: | |
73 | goto fail; | |
74 | } | |
75 | } | |
76 | return acl; | |
77 | ||
78 | fail: | |
79 | posix_acl_release(acl); | |
80 | return ERR_PTR(-EINVAL); | |
81 | } | |
82 | ||
83 | STATIC void | |
84 | xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl) | |
85 | { | |
86 | const struct posix_acl_entry *acl_e; | |
87 | struct xfs_acl_entry *ace; | |
88 | int i; | |
89 | ||
90 | aclp->acl_cnt = cpu_to_be32(acl->a_count); | |
91 | for (i = 0; i < acl->a_count; i++) { | |
92 | ace = &aclp->acl_entry[i]; | |
93 | acl_e = &acl->a_entries[i]; | |
94 | ||
95 | ace->ae_tag = cpu_to_be32(acl_e->e_tag); | |
96 | ace->ae_id = cpu_to_be32(acl_e->e_id); | |
97 | ace->ae_perm = cpu_to_be16(acl_e->e_perm); | |
98 | } | |
99 | } | |
100 | ||
ef14f0c1 CH |
101 | struct posix_acl * |
102 | xfs_get_acl(struct inode *inode, int type) | |
103 | { | |
104 | struct xfs_inode *ip = XFS_I(inode); | |
1cbd20d8 | 105 | struct posix_acl *acl; |
ef14f0c1 CH |
106 | struct xfs_acl *xfs_acl; |
107 | int len = sizeof(struct xfs_acl); | |
108 | char *ea_name; | |
109 | int error; | |
110 | ||
1cbd20d8 AV |
111 | acl = get_cached_acl(inode, type); |
112 | if (acl != ACL_NOT_CACHED) | |
113 | return acl; | |
114 | ||
ef14f0c1 CH |
115 | switch (type) { |
116 | case ACL_TYPE_ACCESS: | |
117 | ea_name = SGI_ACL_FILE; | |
ef14f0c1 CH |
118 | break; |
119 | case ACL_TYPE_DEFAULT: | |
120 | ea_name = SGI_ACL_DEFAULT; | |
ef14f0c1 CH |
121 | break; |
122 | default: | |
1cbd20d8 | 123 | BUG(); |
ef14f0c1 CH |
124 | } |
125 | ||
ef14f0c1 CH |
126 | /* |
127 | * If we have a cached ACLs value just return it, not need to | |
128 | * go out to the disk. | |
129 | */ | |
ef14f0c1 CH |
130 | |
131 | xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL); | |
132 | if (!xfs_acl) | |
133 | return ERR_PTR(-ENOMEM); | |
134 | ||
135 | error = -xfs_attr_get(ip, ea_name, (char *)xfs_acl, &len, ATTR_ROOT); | |
136 | if (error) { | |
137 | /* | |
138 | * If the attribute doesn't exist make sure we have a negative | |
139 | * cache entry, for any other error assume it is transient and | |
1cbd20d8 | 140 | * leave the cache entry as ACL_NOT_CACHED. |
ef14f0c1 CH |
141 | */ |
142 | if (error == -ENOATTR) { | |
143 | acl = NULL; | |
144 | goto out_update_cache; | |
145 | } | |
146 | goto out; | |
147 | } | |
148 | ||
149 | acl = xfs_acl_from_disk(xfs_acl); | |
150 | if (IS_ERR(acl)) | |
151 | goto out; | |
152 | ||
153 | out_update_cache: | |
1cbd20d8 | 154 | set_cached_acl(inode, type, acl); |
ef14f0c1 CH |
155 | out: |
156 | kfree(xfs_acl); | |
157 | return acl; | |
158 | } | |
159 | ||
160 | STATIC int | |
161 | xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl) | |
162 | { | |
163 | struct xfs_inode *ip = XFS_I(inode); | |
ef14f0c1 CH |
164 | char *ea_name; |
165 | int error; | |
166 | ||
167 | if (S_ISLNK(inode->i_mode)) | |
168 | return -EOPNOTSUPP; | |
169 | ||
170 | switch (type) { | |
171 | case ACL_TYPE_ACCESS: | |
172 | ea_name = SGI_ACL_FILE; | |
ef14f0c1 CH |
173 | break; |
174 | case ACL_TYPE_DEFAULT: | |
175 | if (!S_ISDIR(inode->i_mode)) | |
176 | return acl ? -EACCES : 0; | |
177 | ea_name = SGI_ACL_DEFAULT; | |
ef14f0c1 CH |
178 | break; |
179 | default: | |
180 | return -EINVAL; | |
181 | } | |
182 | ||
183 | if (acl) { | |
184 | struct xfs_acl *xfs_acl; | |
185 | int len; | |
186 | ||
187 | xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL); | |
188 | if (!xfs_acl) | |
189 | return -ENOMEM; | |
190 | ||
191 | xfs_acl_to_disk(xfs_acl, acl); | |
192 | len = sizeof(struct xfs_acl) - | |
193 | (sizeof(struct xfs_acl_entry) * | |
194 | (XFS_ACL_MAX_ENTRIES - acl->a_count)); | |
195 | ||
196 | error = -xfs_attr_set(ip, ea_name, (char *)xfs_acl, | |
197 | len, ATTR_ROOT); | |
198 | ||
199 | kfree(xfs_acl); | |
200 | } else { | |
201 | /* | |
202 | * A NULL ACL argument means we want to remove the ACL. | |
203 | */ | |
204 | error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT); | |
205 | ||
206 | /* | |
207 | * If the attribute didn't exist to start with that's fine. | |
208 | */ | |
209 | if (error == -ENOATTR) | |
210 | error = 0; | |
211 | } | |
212 | ||
213 | if (!error) | |
1cbd20d8 | 214 | set_cached_acl(inode, type, acl); |
ef14f0c1 CH |
215 | return error; |
216 | } | |
217 | ||
218 | int | |
219 | xfs_check_acl(struct inode *inode, int mask) | |
220 | { | |
221 | struct xfs_inode *ip = XFS_I(inode); | |
222 | struct posix_acl *acl; | |
223 | int error = -EAGAIN; | |
224 | ||
225 | xfs_itrace_entry(ip); | |
226 | ||
227 | /* | |
228 | * If there is no attribute fork no ACL exists on this inode and | |
229 | * we can skip the whole exercise. | |
230 | */ | |
231 | if (!XFS_IFORK_Q(ip)) | |
232 | return -EAGAIN; | |
233 | ||
234 | acl = xfs_get_acl(inode, ACL_TYPE_ACCESS); | |
235 | if (IS_ERR(acl)) | |
236 | return PTR_ERR(acl); | |
237 | if (acl) { | |
238 | error = posix_acl_permission(inode, acl, mask); | |
239 | posix_acl_release(acl); | |
240 | } | |
241 | ||
242 | return error; | |
243 | } | |
244 | ||
245 | static int | |
246 | xfs_set_mode(struct inode *inode, mode_t mode) | |
247 | { | |
248 | int error = 0; | |
249 | ||
250 | if (mode != inode->i_mode) { | |
251 | struct iattr iattr; | |
252 | ||
253 | iattr.ia_valid = ATTR_MODE; | |
254 | iattr.ia_mode = mode; | |
255 | ||
256 | error = -xfs_setattr(XFS_I(inode), &iattr, XFS_ATTR_NOACL); | |
257 | } | |
258 | ||
259 | return error; | |
260 | } | |
261 | ||
262 | static int | |
263 | xfs_acl_exists(struct inode *inode, char *name) | |
264 | { | |
265 | int len = sizeof(struct xfs_acl); | |
266 | ||
267 | return (xfs_attr_get(XFS_I(inode), name, NULL, &len, | |
268 | ATTR_ROOT|ATTR_KERNOVAL) == 0); | |
269 | } | |
270 | ||
271 | int | |
272 | posix_acl_access_exists(struct inode *inode) | |
273 | { | |
274 | return xfs_acl_exists(inode, SGI_ACL_FILE); | |
275 | } | |
276 | ||
277 | int | |
278 | posix_acl_default_exists(struct inode *inode) | |
279 | { | |
280 | if (!S_ISDIR(inode->i_mode)) | |
281 | return 0; | |
282 | return xfs_acl_exists(inode, SGI_ACL_DEFAULT); | |
283 | } | |
284 | ||
285 | /* | |
286 | * No need for i_mutex because the inode is not yet exposed to the VFS. | |
287 | */ | |
288 | int | |
289 | xfs_inherit_acl(struct inode *inode, struct posix_acl *default_acl) | |
290 | { | |
291 | struct posix_acl *clone; | |
292 | mode_t mode; | |
293 | int error = 0, inherit = 0; | |
294 | ||
295 | if (S_ISDIR(inode->i_mode)) { | |
296 | error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl); | |
297 | if (error) | |
298 | return error; | |
299 | } | |
300 | ||
301 | clone = posix_acl_clone(default_acl, GFP_KERNEL); | |
302 | if (!clone) | |
303 | return -ENOMEM; | |
304 | ||
305 | mode = inode->i_mode; | |
306 | error = posix_acl_create_masq(clone, &mode); | |
307 | if (error < 0) | |
308 | goto out_release_clone; | |
309 | ||
310 | /* | |
311 | * If posix_acl_create_masq returns a positive value we need to | |
312 | * inherit a permission that can't be represented using the Unix | |
313 | * mode bits and we actually need to set an ACL. | |
314 | */ | |
315 | if (error > 0) | |
316 | inherit = 1; | |
317 | ||
318 | error = xfs_set_mode(inode, mode); | |
319 | if (error) | |
320 | goto out_release_clone; | |
321 | ||
322 | if (inherit) | |
323 | error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone); | |
324 | ||
325 | out_release_clone: | |
326 | posix_acl_release(clone); | |
327 | return error; | |
328 | } | |
329 | ||
330 | int | |
331 | xfs_acl_chmod(struct inode *inode) | |
332 | { | |
333 | struct posix_acl *acl, *clone; | |
334 | int error; | |
335 | ||
336 | if (S_ISLNK(inode->i_mode)) | |
337 | return -EOPNOTSUPP; | |
338 | ||
339 | acl = xfs_get_acl(inode, ACL_TYPE_ACCESS); | |
340 | if (IS_ERR(acl) || !acl) | |
341 | return PTR_ERR(acl); | |
342 | ||
343 | clone = posix_acl_clone(acl, GFP_KERNEL); | |
344 | posix_acl_release(acl); | |
345 | if (!clone) | |
346 | return -ENOMEM; | |
347 | ||
348 | error = posix_acl_chmod_masq(clone, inode->i_mode); | |
349 | if (!error) | |
350 | error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone); | |
351 | ||
352 | posix_acl_release(clone); | |
353 | return error; | |
354 | } | |
355 | ||
ef14f0c1 CH |
356 | /* |
357 | * System xattr handlers. | |
358 | * | |
359 | * Currently Posix ACLs are the only system namespace extended attribute | |
360 | * handlers supported by XFS, so we just implement the handlers here. | |
361 | * If we ever support other system extended attributes this will need | |
362 | * some refactoring. | |
363 | */ | |
364 | ||
365 | static int | |
366 | xfs_decode_acl(const char *name) | |
367 | { | |
368 | if (strcmp(name, "posix_acl_access") == 0) | |
369 | return ACL_TYPE_ACCESS; | |
370 | else if (strcmp(name, "posix_acl_default") == 0) | |
371 | return ACL_TYPE_DEFAULT; | |
372 | return -EINVAL; | |
373 | } | |
374 | ||
375 | static int | |
376 | xfs_xattr_system_get(struct inode *inode, const char *name, | |
377 | void *value, size_t size) | |
378 | { | |
379 | struct posix_acl *acl; | |
380 | int type, error; | |
381 | ||
382 | type = xfs_decode_acl(name); | |
383 | if (type < 0) | |
384 | return type; | |
385 | ||
386 | acl = xfs_get_acl(inode, type); | |
387 | if (IS_ERR(acl)) | |
388 | return PTR_ERR(acl); | |
389 | if (acl == NULL) | |
390 | return -ENODATA; | |
391 | ||
392 | error = posix_acl_to_xattr(acl, value, size); | |
393 | posix_acl_release(acl); | |
394 | ||
395 | return error; | |
396 | } | |
397 | ||
398 | static int | |
399 | xfs_xattr_system_set(struct inode *inode, const char *name, | |
400 | const void *value, size_t size, int flags) | |
401 | { | |
402 | struct posix_acl *acl = NULL; | |
403 | int error = 0, type; | |
404 | ||
405 | type = xfs_decode_acl(name); | |
406 | if (type < 0) | |
407 | return type; | |
408 | if (flags & XATTR_CREATE) | |
409 | return -EINVAL; | |
410 | if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) | |
411 | return value ? -EACCES : 0; | |
412 | if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER)) | |
413 | return -EPERM; | |
414 | ||
415 | if (!value) | |
416 | goto set_acl; | |
417 | ||
418 | acl = posix_acl_from_xattr(value, size); | |
419 | if (!acl) { | |
420 | /* | |
421 | * acl_set_file(3) may request that we set default ACLs with | |
422 | * zero length -- defend (gracefully) against that here. | |
423 | */ | |
424 | goto out; | |
425 | } | |
426 | if (IS_ERR(acl)) { | |
427 | error = PTR_ERR(acl); | |
428 | goto out; | |
429 | } | |
430 | ||
431 | error = posix_acl_valid(acl); | |
432 | if (error) | |
433 | goto out_release; | |
434 | ||
435 | error = -EINVAL; | |
436 | if (acl->a_count > XFS_ACL_MAX_ENTRIES) | |
437 | goto out_release; | |
438 | ||
439 | if (type == ACL_TYPE_ACCESS) { | |
440 | mode_t mode = inode->i_mode; | |
441 | error = posix_acl_equiv_mode(acl, &mode); | |
442 | ||
443 | if (error <= 0) { | |
444 | posix_acl_release(acl); | |
445 | acl = NULL; | |
446 | ||
447 | if (error < 0) | |
448 | return error; | |
449 | } | |
450 | ||
451 | error = xfs_set_mode(inode, mode); | |
452 | if (error) | |
453 | goto out_release; | |
454 | } | |
455 | ||
456 | set_acl: | |
457 | error = xfs_set_acl(inode, type, acl); | |
458 | out_release: | |
459 | posix_acl_release(acl); | |
460 | out: | |
461 | return error; | |
462 | } | |
463 | ||
464 | struct xattr_handler xfs_xattr_system_handler = { | |
465 | .prefix = XATTR_SYSTEM_PREFIX, | |
466 | .get = xfs_xattr_system_get, | |
467 | .set = xfs_xattr_system_set, | |
468 | }; |