Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/fs/posix_acl.c | |
3 | * | |
4 | * Copyright (C) 2002 by Andreas Gruenbacher <a.gruenbacher@computer.org> | |
5 | * | |
6 | * Fixes from William Schumacher incorporated on 15 March 2001. | |
7 | * (Reported by Charles Bertsch, <CBertsch@microtest.com>). | |
8 | */ | |
9 | ||
10 | /* | |
11 | * This file contains generic functions for manipulating | |
12 | * POSIX 1003.1e draft standard 17 ACLs. | |
13 | */ | |
14 | ||
15 | #include <linux/kernel.h> | |
16 | #include <linux/slab.h> | |
60063497 | 17 | #include <linux/atomic.h> |
1da177e4 LT |
18 | #include <linux/fs.h> |
19 | #include <linux/sched.h> | |
20 | #include <linux/posix_acl.h> | |
630d9c47 | 21 | #include <linux/export.h> |
1da177e4 LT |
22 | |
23 | #include <linux/errno.h> | |
24 | ||
0afaa120 AM |
25 | struct posix_acl **acl_by_type(struct inode *inode, int type) |
26 | { | |
27 | switch (type) { | |
28 | case ACL_TYPE_ACCESS: | |
29 | return &inode->i_acl; | |
30 | case ACL_TYPE_DEFAULT: | |
31 | return &inode->i_default_acl; | |
32 | default: | |
33 | BUG(); | |
34 | } | |
35 | } | |
36 | EXPORT_SYMBOL(acl_by_type); | |
37 | ||
38 | struct posix_acl *get_cached_acl(struct inode *inode, int type) | |
39 | { | |
40 | struct posix_acl **p = acl_by_type(inode, type); | |
41 | struct posix_acl *acl = ACCESS_ONCE(*p); | |
42 | if (acl) { | |
43 | spin_lock(&inode->i_lock); | |
44 | acl = *p; | |
45 | if (acl != ACL_NOT_CACHED) | |
46 | acl = posix_acl_dup(acl); | |
47 | spin_unlock(&inode->i_lock); | |
48 | } | |
49 | return acl; | |
50 | } | |
51 | EXPORT_SYMBOL(get_cached_acl); | |
52 | ||
53 | struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type) | |
54 | { | |
55 | return rcu_dereference(*acl_by_type(inode, type)); | |
56 | } | |
57 | EXPORT_SYMBOL(get_cached_acl_rcu); | |
58 | ||
59 | void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl) | |
60 | { | |
61 | struct posix_acl **p = acl_by_type(inode, type); | |
62 | struct posix_acl *old; | |
63 | spin_lock(&inode->i_lock); | |
64 | old = *p; | |
65 | rcu_assign_pointer(*p, posix_acl_dup(acl)); | |
66 | spin_unlock(&inode->i_lock); | |
67 | if (old != ACL_NOT_CACHED) | |
68 | posix_acl_release(old); | |
69 | } | |
70 | EXPORT_SYMBOL(set_cached_acl); | |
71 | ||
72 | void forget_cached_acl(struct inode *inode, int type) | |
73 | { | |
74 | struct posix_acl **p = acl_by_type(inode, type); | |
75 | struct posix_acl *old; | |
76 | spin_lock(&inode->i_lock); | |
77 | old = *p; | |
78 | *p = ACL_NOT_CACHED; | |
79 | spin_unlock(&inode->i_lock); | |
80 | if (old != ACL_NOT_CACHED) | |
81 | posix_acl_release(old); | |
82 | } | |
83 | EXPORT_SYMBOL(forget_cached_acl); | |
84 | ||
85 | void forget_all_cached_acls(struct inode *inode) | |
86 | { | |
87 | struct posix_acl *old_access, *old_default; | |
88 | spin_lock(&inode->i_lock); | |
89 | old_access = inode->i_acl; | |
90 | old_default = inode->i_default_acl; | |
91 | inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED; | |
92 | spin_unlock(&inode->i_lock); | |
93 | if (old_access != ACL_NOT_CACHED) | |
94 | posix_acl_release(old_access); | |
95 | if (old_default != ACL_NOT_CACHED) | |
96 | posix_acl_release(old_default); | |
97 | } | |
98 | EXPORT_SYMBOL(forget_all_cached_acls); | |
1da177e4 | 99 | |
f61f6da0 CL |
100 | /* |
101 | * Init a fresh posix_acl | |
102 | */ | |
103 | void | |
104 | posix_acl_init(struct posix_acl *acl, int count) | |
105 | { | |
106 | atomic_set(&acl->a_refcount, 1); | |
107 | acl->a_count = count; | |
108 | } | |
0afaa120 | 109 | EXPORT_SYMBOL(posix_acl_init); |
f61f6da0 | 110 | |
1da177e4 LT |
111 | /* |
112 | * Allocate a new ACL with the specified number of entries. | |
113 | */ | |
114 | struct posix_acl * | |
dd0fc66f | 115 | posix_acl_alloc(int count, gfp_t flags) |
1da177e4 LT |
116 | { |
117 | const size_t size = sizeof(struct posix_acl) + | |
118 | count * sizeof(struct posix_acl_entry); | |
119 | struct posix_acl *acl = kmalloc(size, flags); | |
f61f6da0 CL |
120 | if (acl) |
121 | posix_acl_init(acl, count); | |
1da177e4 LT |
122 | return acl; |
123 | } | |
0afaa120 | 124 | EXPORT_SYMBOL(posix_acl_alloc); |
1da177e4 LT |
125 | |
126 | /* | |
127 | * Clone an ACL. | |
128 | */ | |
edde854e | 129 | static struct posix_acl * |
dd0fc66f | 130 | posix_acl_clone(const struct posix_acl *acl, gfp_t flags) |
1da177e4 LT |
131 | { |
132 | struct posix_acl *clone = NULL; | |
133 | ||
134 | if (acl) { | |
135 | int size = sizeof(struct posix_acl) + acl->a_count * | |
136 | sizeof(struct posix_acl_entry); | |
52978be6 AD |
137 | clone = kmemdup(acl, size, flags); |
138 | if (clone) | |
1da177e4 | 139 | atomic_set(&clone->a_refcount, 1); |
1da177e4 LT |
140 | } |
141 | return clone; | |
142 | } | |
143 | ||
144 | /* | |
145 | * Check if an acl is valid. Returns 0 if it is, or -E... otherwise. | |
146 | */ | |
147 | int | |
148 | posix_acl_valid(const struct posix_acl *acl) | |
149 | { | |
150 | const struct posix_acl_entry *pa, *pe; | |
151 | int state = ACL_USER_OBJ; | |
1da177e4 LT |
152 | int needs_mask = 0; |
153 | ||
154 | FOREACH_ACL_ENTRY(pa, acl, pe) { | |
155 | if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE)) | |
156 | return -EINVAL; | |
157 | switch (pa->e_tag) { | |
158 | case ACL_USER_OBJ: | |
159 | if (state == ACL_USER_OBJ) { | |
1da177e4 LT |
160 | state = ACL_USER; |
161 | break; | |
162 | } | |
163 | return -EINVAL; | |
164 | ||
165 | case ACL_USER: | |
166 | if (state != ACL_USER) | |
167 | return -EINVAL; | |
2f6f0654 | 168 | if (!uid_valid(pa->e_uid)) |
1da177e4 | 169 | return -EINVAL; |
1da177e4 LT |
170 | needs_mask = 1; |
171 | break; | |
172 | ||
173 | case ACL_GROUP_OBJ: | |
174 | if (state == ACL_USER) { | |
1da177e4 LT |
175 | state = ACL_GROUP; |
176 | break; | |
177 | } | |
178 | return -EINVAL; | |
179 | ||
180 | case ACL_GROUP: | |
181 | if (state != ACL_GROUP) | |
182 | return -EINVAL; | |
2f6f0654 EB |
183 | if (!gid_valid(pa->e_gid)) |
184 | return -EINVAL; | |
1da177e4 LT |
185 | needs_mask = 1; |
186 | break; | |
187 | ||
188 | case ACL_MASK: | |
189 | if (state != ACL_GROUP) | |
190 | return -EINVAL; | |
191 | state = ACL_OTHER; | |
192 | break; | |
193 | ||
194 | case ACL_OTHER: | |
195 | if (state == ACL_OTHER || | |
196 | (state == ACL_GROUP && !needs_mask)) { | |
197 | state = 0; | |
198 | break; | |
199 | } | |
200 | return -EINVAL; | |
201 | ||
202 | default: | |
203 | return -EINVAL; | |
204 | } | |
205 | } | |
206 | if (state == 0) | |
207 | return 0; | |
208 | return -EINVAL; | |
209 | } | |
0afaa120 | 210 | EXPORT_SYMBOL(posix_acl_valid); |
1da177e4 LT |
211 | |
212 | /* | |
213 | * Returns 0 if the acl can be exactly represented in the traditional | |
214 | * file mode permission bits, or else 1. Returns -E... on error. | |
215 | */ | |
216 | int | |
d6952123 | 217 | posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p) |
1da177e4 LT |
218 | { |
219 | const struct posix_acl_entry *pa, *pe; | |
d6952123 | 220 | umode_t mode = 0; |
1da177e4 LT |
221 | int not_equiv = 0; |
222 | ||
223 | FOREACH_ACL_ENTRY(pa, acl, pe) { | |
224 | switch (pa->e_tag) { | |
225 | case ACL_USER_OBJ: | |
226 | mode |= (pa->e_perm & S_IRWXO) << 6; | |
227 | break; | |
228 | case ACL_GROUP_OBJ: | |
229 | mode |= (pa->e_perm & S_IRWXO) << 3; | |
230 | break; | |
231 | case ACL_OTHER: | |
232 | mode |= pa->e_perm & S_IRWXO; | |
233 | break; | |
234 | case ACL_MASK: | |
235 | mode = (mode & ~S_IRWXG) | | |
236 | ((pa->e_perm & S_IRWXO) << 3); | |
237 | not_equiv = 1; | |
238 | break; | |
239 | case ACL_USER: | |
240 | case ACL_GROUP: | |
241 | not_equiv = 1; | |
242 | break; | |
243 | default: | |
244 | return -EINVAL; | |
245 | } | |
246 | } | |
247 | if (mode_p) | |
248 | *mode_p = (*mode_p & ~S_IRWXUGO) | mode; | |
249 | return not_equiv; | |
250 | } | |
0afaa120 | 251 | EXPORT_SYMBOL(posix_acl_equiv_mode); |
1da177e4 LT |
252 | |
253 | /* | |
254 | * Create an ACL representing the file mode permission bits of an inode. | |
255 | */ | |
256 | struct posix_acl * | |
3a5fba19 | 257 | posix_acl_from_mode(umode_t mode, gfp_t flags) |
1da177e4 LT |
258 | { |
259 | struct posix_acl *acl = posix_acl_alloc(3, flags); | |
260 | if (!acl) | |
261 | return ERR_PTR(-ENOMEM); | |
262 | ||
263 | acl->a_entries[0].e_tag = ACL_USER_OBJ; | |
1da177e4 LT |
264 | acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6; |
265 | ||
266 | acl->a_entries[1].e_tag = ACL_GROUP_OBJ; | |
1da177e4 LT |
267 | acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3; |
268 | ||
269 | acl->a_entries[2].e_tag = ACL_OTHER; | |
1da177e4 LT |
270 | acl->a_entries[2].e_perm = (mode & S_IRWXO); |
271 | return acl; | |
272 | } | |
0afaa120 | 273 | EXPORT_SYMBOL(posix_acl_from_mode); |
1da177e4 LT |
274 | |
275 | /* | |
276 | * Return 0 if current is granted want access to the inode | |
277 | * by the acl. Returns -E... otherwise. | |
278 | */ | |
279 | int | |
280 | posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want) | |
281 | { | |
282 | const struct posix_acl_entry *pa, *pe, *mask_obj; | |
283 | int found = 0; | |
284 | ||
d124b60a AG |
285 | want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK; |
286 | ||
1da177e4 LT |
287 | FOREACH_ACL_ENTRY(pa, acl, pe) { |
288 | switch(pa->e_tag) { | |
289 | case ACL_USER_OBJ: | |
290 | /* (May have been checked already) */ | |
2f6f0654 | 291 | if (uid_eq(inode->i_uid, current_fsuid())) |
1da177e4 LT |
292 | goto check_perm; |
293 | break; | |
294 | case ACL_USER: | |
2f6f0654 | 295 | if (uid_eq(pa->e_uid, current_fsuid())) |
1da177e4 LT |
296 | goto mask; |
297 | break; | |
298 | case ACL_GROUP_OBJ: | |
299 | if (in_group_p(inode->i_gid)) { | |
300 | found = 1; | |
301 | if ((pa->e_perm & want) == want) | |
302 | goto mask; | |
303 | } | |
304 | break; | |
305 | case ACL_GROUP: | |
2f6f0654 | 306 | if (in_group_p(pa->e_gid)) { |
1da177e4 LT |
307 | found = 1; |
308 | if ((pa->e_perm & want) == want) | |
309 | goto mask; | |
310 | } | |
311 | break; | |
312 | case ACL_MASK: | |
313 | break; | |
314 | case ACL_OTHER: | |
315 | if (found) | |
316 | return -EACCES; | |
317 | else | |
318 | goto check_perm; | |
319 | default: | |
320 | return -EIO; | |
321 | } | |
322 | } | |
323 | return -EIO; | |
324 | ||
325 | mask: | |
326 | for (mask_obj = pa+1; mask_obj != pe; mask_obj++) { | |
327 | if (mask_obj->e_tag == ACL_MASK) { | |
328 | if ((pa->e_perm & mask_obj->e_perm & want) == want) | |
329 | return 0; | |
330 | return -EACCES; | |
331 | } | |
332 | } | |
333 | ||
334 | check_perm: | |
335 | if ((pa->e_perm & want) == want) | |
336 | return 0; | |
337 | return -EACCES; | |
338 | } | |
339 | ||
340 | /* | |
341 | * Modify acl when creating a new inode. The caller must ensure the acl is | |
342 | * only referenced once. | |
343 | * | |
344 | * mode_p initially must contain the mode parameter to the open() / creat() | |
345 | * system calls. All permissions that are not granted by the acl are removed. | |
346 | * The permissions in the acl are changed to reflect the mode_p parameter. | |
347 | */ | |
d3fb6120 | 348 | static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p) |
1da177e4 LT |
349 | { |
350 | struct posix_acl_entry *pa, *pe; | |
351 | struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; | |
d3fb6120 | 352 | umode_t mode = *mode_p; |
1da177e4 LT |
353 | int not_equiv = 0; |
354 | ||
355 | /* assert(atomic_read(acl->a_refcount) == 1); */ | |
356 | ||
357 | FOREACH_ACL_ENTRY(pa, acl, pe) { | |
358 | switch(pa->e_tag) { | |
359 | case ACL_USER_OBJ: | |
360 | pa->e_perm &= (mode >> 6) | ~S_IRWXO; | |
361 | mode &= (pa->e_perm << 6) | ~S_IRWXU; | |
362 | break; | |
363 | ||
364 | case ACL_USER: | |
365 | case ACL_GROUP: | |
366 | not_equiv = 1; | |
367 | break; | |
368 | ||
369 | case ACL_GROUP_OBJ: | |
370 | group_obj = pa; | |
371 | break; | |
372 | ||
373 | case ACL_OTHER: | |
374 | pa->e_perm &= mode | ~S_IRWXO; | |
375 | mode &= pa->e_perm | ~S_IRWXO; | |
376 | break; | |
377 | ||
378 | case ACL_MASK: | |
379 | mask_obj = pa; | |
380 | not_equiv = 1; | |
381 | break; | |
382 | ||
383 | default: | |
384 | return -EIO; | |
385 | } | |
386 | } | |
387 | ||
388 | if (mask_obj) { | |
389 | mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO; | |
390 | mode &= (mask_obj->e_perm << 3) | ~S_IRWXG; | |
391 | } else { | |
392 | if (!group_obj) | |
393 | return -EIO; | |
394 | group_obj->e_perm &= (mode >> 3) | ~S_IRWXO; | |
395 | mode &= (group_obj->e_perm << 3) | ~S_IRWXG; | |
396 | } | |
397 | ||
398 | *mode_p = (*mode_p & ~S_IRWXUGO) | mode; | |
399 | return not_equiv; | |
400 | } | |
401 | ||
402 | /* | |
403 | * Modify the ACL for the chmod syscall. | |
404 | */ | |
86bc704d | 405 | static int posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode) |
1da177e4 LT |
406 | { |
407 | struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; | |
408 | struct posix_acl_entry *pa, *pe; | |
409 | ||
410 | /* assert(atomic_read(acl->a_refcount) == 1); */ | |
411 | ||
412 | FOREACH_ACL_ENTRY(pa, acl, pe) { | |
413 | switch(pa->e_tag) { | |
414 | case ACL_USER_OBJ: | |
415 | pa->e_perm = (mode & S_IRWXU) >> 6; | |
416 | break; | |
417 | ||
418 | case ACL_USER: | |
419 | case ACL_GROUP: | |
420 | break; | |
421 | ||
422 | case ACL_GROUP_OBJ: | |
423 | group_obj = pa; | |
424 | break; | |
425 | ||
426 | case ACL_MASK: | |
427 | mask_obj = pa; | |
428 | break; | |
429 | ||
430 | case ACL_OTHER: | |
431 | pa->e_perm = (mode & S_IRWXO); | |
432 | break; | |
433 | ||
434 | default: | |
435 | return -EIO; | |
436 | } | |
437 | } | |
438 | ||
439 | if (mask_obj) { | |
440 | mask_obj->e_perm = (mode & S_IRWXG) >> 3; | |
441 | } else { | |
442 | if (!group_obj) | |
443 | return -EIO; | |
444 | group_obj->e_perm = (mode & S_IRWXG) >> 3; | |
445 | } | |
446 | ||
447 | return 0; | |
448 | } | |
bc26ab5f | 449 | |
826cae2f | 450 | int |
d3fb6120 | 451 | posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p) |
826cae2f AV |
452 | { |
453 | struct posix_acl *clone = posix_acl_clone(*acl, gfp); | |
454 | int err = -ENOMEM; | |
455 | if (clone) { | |
456 | err = posix_acl_create_masq(clone, mode_p); | |
457 | if (err < 0) { | |
458 | posix_acl_release(clone); | |
459 | clone = NULL; | |
460 | } | |
461 | } | |
462 | posix_acl_release(*acl); | |
463 | *acl = clone; | |
464 | return err; | |
465 | } | |
466 | EXPORT_SYMBOL(posix_acl_create); | |
467 | ||
bc26ab5f | 468 | int |
86bc704d | 469 | posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode) |
bc26ab5f AV |
470 | { |
471 | struct posix_acl *clone = posix_acl_clone(*acl, gfp); | |
472 | int err = -ENOMEM; | |
473 | if (clone) { | |
474 | err = posix_acl_chmod_masq(clone, mode); | |
475 | if (err) { | |
476 | posix_acl_release(clone); | |
477 | clone = NULL; | |
478 | } | |
479 | } | |
480 | posix_acl_release(*acl); | |
481 | *acl = clone; | |
482 | return err; | |
483 | } | |
484 | EXPORT_SYMBOL(posix_acl_chmod); |