Commit | Line | Data |
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1da177e4 LT |
1 | /* keyring.c: keyring handling |
2 | * | |
3e30148c | 3 | * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved. |
1da177e4 LT |
4 | * Written by David Howells (dhowells@redhat.com) |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/sched.h> | |
15 | #include <linux/slab.h> | |
29db9190 | 16 | #include <linux/security.h> |
1da177e4 LT |
17 | #include <linux/seq_file.h> |
18 | #include <linux/err.h> | |
19 | #include <asm/uaccess.h> | |
20 | #include "internal.h" | |
21 | ||
22 | /* | |
23 | * when plumbing the depths of the key tree, this sets a hard limit set on how | |
24 | * deep we're willing to go | |
25 | */ | |
26 | #define KEYRING_SEARCH_MAX_DEPTH 6 | |
27 | ||
28 | /* | |
29 | * we keep all named keyrings in a hash to speed looking them up | |
30 | */ | |
31 | #define KEYRING_NAME_HASH_SIZE (1 << 5) | |
32 | ||
33 | static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE]; | |
34 | static DEFINE_RWLOCK(keyring_name_lock); | |
35 | ||
36 | static inline unsigned keyring_hash(const char *desc) | |
37 | { | |
38 | unsigned bucket = 0; | |
39 | ||
40 | for (; *desc; desc++) | |
41 | bucket += (unsigned char) *desc; | |
42 | ||
43 | return bucket & (KEYRING_NAME_HASH_SIZE - 1); | |
44 | } | |
45 | ||
46 | /* | |
47 | * the keyring type definition | |
48 | */ | |
49 | static int keyring_instantiate(struct key *keyring, | |
50 | const void *data, size_t datalen); | |
51 | static int keyring_duplicate(struct key *keyring, const struct key *source); | |
52 | static int keyring_match(const struct key *keyring, const void *criterion); | |
53 | static void keyring_destroy(struct key *keyring); | |
54 | static void keyring_describe(const struct key *keyring, struct seq_file *m); | |
55 | static long keyring_read(const struct key *keyring, | |
56 | char __user *buffer, size_t buflen); | |
57 | ||
58 | struct key_type key_type_keyring = { | |
59 | .name = "keyring", | |
60 | .def_datalen = sizeof(struct keyring_list), | |
61 | .instantiate = keyring_instantiate, | |
62 | .duplicate = keyring_duplicate, | |
63 | .match = keyring_match, | |
64 | .destroy = keyring_destroy, | |
65 | .describe = keyring_describe, | |
66 | .read = keyring_read, | |
67 | }; | |
68 | ||
69 | /* | |
70 | * semaphore to serialise link/link calls to prevent two link calls in parallel | |
71 | * introducing a cycle | |
72 | */ | |
73 | DECLARE_RWSEM(keyring_serialise_link_sem); | |
74 | ||
75 | /*****************************************************************************/ | |
76 | /* | |
77 | * publish the name of a keyring so that it can be found by name (if it has | |
78 | * one) | |
79 | */ | |
80 | void keyring_publish_name(struct key *keyring) | |
81 | { | |
82 | int bucket; | |
83 | ||
84 | if (keyring->description) { | |
85 | bucket = keyring_hash(keyring->description); | |
86 | ||
87 | write_lock(&keyring_name_lock); | |
88 | ||
89 | if (!keyring_name_hash[bucket].next) | |
90 | INIT_LIST_HEAD(&keyring_name_hash[bucket]); | |
91 | ||
92 | list_add_tail(&keyring->type_data.link, | |
93 | &keyring_name_hash[bucket]); | |
94 | ||
95 | write_unlock(&keyring_name_lock); | |
96 | } | |
97 | ||
98 | } /* end keyring_publish_name() */ | |
99 | ||
100 | /*****************************************************************************/ | |
101 | /* | |
102 | * initialise a keyring | |
103 | * - we object if we were given any data | |
104 | */ | |
105 | static int keyring_instantiate(struct key *keyring, | |
106 | const void *data, size_t datalen) | |
107 | { | |
108 | int ret; | |
109 | ||
110 | ret = -EINVAL; | |
111 | if (datalen == 0) { | |
112 | /* make the keyring available by name if it has one */ | |
113 | keyring_publish_name(keyring); | |
114 | ret = 0; | |
115 | } | |
116 | ||
117 | return ret; | |
118 | ||
119 | } /* end keyring_instantiate() */ | |
120 | ||
121 | /*****************************************************************************/ | |
122 | /* | |
123 | * duplicate the list of subscribed keys from a source keyring into this one | |
124 | */ | |
125 | static int keyring_duplicate(struct key *keyring, const struct key *source) | |
126 | { | |
127 | struct keyring_list *sklist, *klist; | |
128 | unsigned max; | |
129 | size_t size; | |
130 | int loop, ret; | |
131 | ||
132 | const unsigned limit = | |
a4014d8f | 133 | (PAGE_SIZE - sizeof(*klist)) / sizeof(struct key *); |
1da177e4 LT |
134 | |
135 | ret = 0; | |
1da177e4 | 136 | |
76d8aeab DH |
137 | /* find out how many keys are currently linked */ |
138 | rcu_read_lock(); | |
139 | sklist = rcu_dereference(source->payload.subscriptions); | |
140 | max = 0; | |
141 | if (sklist) | |
1da177e4 | 142 | max = sklist->nkeys; |
76d8aeab DH |
143 | rcu_read_unlock(); |
144 | ||
145 | /* allocate a new payload and stuff load with key links */ | |
146 | if (max > 0) { | |
1da177e4 LT |
147 | BUG_ON(max > limit); |
148 | ||
149 | max = (max + 3) & ~3; | |
150 | if (max > limit) | |
151 | max = limit; | |
152 | ||
153 | ret = -ENOMEM; | |
a4014d8f | 154 | size = sizeof(*klist) + sizeof(struct key *) * max; |
1da177e4 LT |
155 | klist = kmalloc(size, GFP_KERNEL); |
156 | if (!klist) | |
157 | goto error; | |
158 | ||
76d8aeab DH |
159 | /* set links */ |
160 | rcu_read_lock(); | |
161 | sklist = rcu_dereference(source->payload.subscriptions); | |
162 | ||
1da177e4 LT |
163 | klist->maxkeys = max; |
164 | klist->nkeys = sklist->nkeys; | |
165 | memcpy(klist->keys, | |
166 | sklist->keys, | |
a4014d8f | 167 | sklist->nkeys * sizeof(struct key *)); |
1da177e4 LT |
168 | |
169 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
170 | atomic_inc(&klist->keys[loop]->usage); | |
171 | ||
76d8aeab DH |
172 | rcu_read_unlock(); |
173 | ||
174 | rcu_assign_pointer(keyring->payload.subscriptions, klist); | |
1da177e4 LT |
175 | ret = 0; |
176 | } | |
177 | ||
178 | error: | |
179 | return ret; | |
180 | ||
181 | } /* end keyring_duplicate() */ | |
182 | ||
183 | /*****************************************************************************/ | |
184 | /* | |
185 | * match keyrings on their name | |
186 | */ | |
187 | static int keyring_match(const struct key *keyring, const void *description) | |
188 | { | |
189 | return keyring->description && | |
190 | strcmp(keyring->description, description) == 0; | |
191 | ||
192 | } /* end keyring_match() */ | |
193 | ||
194 | /*****************************************************************************/ | |
195 | /* | |
196 | * dispose of the data dangling from the corpse of a keyring | |
197 | */ | |
198 | static void keyring_destroy(struct key *keyring) | |
199 | { | |
200 | struct keyring_list *klist; | |
201 | int loop; | |
202 | ||
203 | if (keyring->description) { | |
204 | write_lock(&keyring_name_lock); | |
94efe72f DH |
205 | |
206 | if (keyring->type_data.link.next != NULL && | |
207 | !list_empty(&keyring->type_data.link)) | |
208 | list_del(&keyring->type_data.link); | |
209 | ||
1da177e4 LT |
210 | write_unlock(&keyring_name_lock); |
211 | } | |
212 | ||
76d8aeab | 213 | klist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
214 | if (klist) { |
215 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
216 | key_put(klist->keys[loop]); | |
217 | kfree(klist); | |
218 | } | |
219 | ||
220 | } /* end keyring_destroy() */ | |
221 | ||
222 | /*****************************************************************************/ | |
223 | /* | |
224 | * describe the keyring | |
225 | */ | |
226 | static void keyring_describe(const struct key *keyring, struct seq_file *m) | |
227 | { | |
228 | struct keyring_list *klist; | |
229 | ||
230 | if (keyring->description) { | |
231 | seq_puts(m, keyring->description); | |
232 | } | |
233 | else { | |
234 | seq_puts(m, "[anon]"); | |
235 | } | |
236 | ||
76d8aeab DH |
237 | rcu_read_lock(); |
238 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
239 | if (klist) |
240 | seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys); | |
241 | else | |
242 | seq_puts(m, ": empty"); | |
76d8aeab | 243 | rcu_read_unlock(); |
1da177e4 LT |
244 | |
245 | } /* end keyring_describe() */ | |
246 | ||
247 | /*****************************************************************************/ | |
248 | /* | |
249 | * read a list of key IDs from the keyring's contents | |
76d8aeab | 250 | * - the keyring's semaphore is read-locked |
1da177e4 LT |
251 | */ |
252 | static long keyring_read(const struct key *keyring, | |
253 | char __user *buffer, size_t buflen) | |
254 | { | |
255 | struct keyring_list *klist; | |
256 | struct key *key; | |
257 | size_t qty, tmp; | |
258 | int loop, ret; | |
259 | ||
260 | ret = 0; | |
76d8aeab | 261 | klist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
262 | |
263 | if (klist) { | |
264 | /* calculate how much data we could return */ | |
265 | qty = klist->nkeys * sizeof(key_serial_t); | |
266 | ||
267 | if (buffer && buflen > 0) { | |
268 | if (buflen > qty) | |
269 | buflen = qty; | |
270 | ||
271 | /* copy the IDs of the subscribed keys into the | |
272 | * buffer */ | |
273 | ret = -EFAULT; | |
274 | ||
275 | for (loop = 0; loop < klist->nkeys; loop++) { | |
276 | key = klist->keys[loop]; | |
277 | ||
278 | tmp = sizeof(key_serial_t); | |
279 | if (tmp > buflen) | |
280 | tmp = buflen; | |
281 | ||
282 | if (copy_to_user(buffer, | |
283 | &key->serial, | |
284 | tmp) != 0) | |
285 | goto error; | |
286 | ||
287 | buflen -= tmp; | |
288 | if (buflen == 0) | |
289 | break; | |
290 | buffer += tmp; | |
291 | } | |
292 | } | |
293 | ||
294 | ret = qty; | |
295 | } | |
296 | ||
297 | error: | |
298 | return ret; | |
299 | ||
300 | } /* end keyring_read() */ | |
301 | ||
302 | /*****************************************************************************/ | |
303 | /* | |
304 | * allocate a keyring and link into the destination keyring | |
305 | */ | |
306 | struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, | |
307 | int not_in_quota, struct key *dest) | |
308 | { | |
309 | struct key *keyring; | |
310 | int ret; | |
311 | ||
312 | keyring = key_alloc(&key_type_keyring, description, | |
29db9190 DH |
313 | uid, gid, |
314 | (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, | |
315 | not_in_quota); | |
1da177e4 LT |
316 | |
317 | if (!IS_ERR(keyring)) { | |
3e30148c | 318 | ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); |
1da177e4 LT |
319 | if (ret < 0) { |
320 | key_put(keyring); | |
321 | keyring = ERR_PTR(ret); | |
322 | } | |
323 | } | |
324 | ||
325 | return keyring; | |
326 | ||
327 | } /* end keyring_alloc() */ | |
328 | ||
329 | /*****************************************************************************/ | |
330 | /* | |
331 | * search the supplied keyring tree for a key that matches the criterion | |
332 | * - perform a breadth-then-depth search up to the prescribed limit | |
333 | * - we only find keys on which we have search permission | |
334 | * - we use the supplied match function to see if the description (or other | |
335 | * feature of interest) matches | |
3e30148c | 336 | * - we rely on RCU to prevent the keyring lists from disappearing on us |
1da177e4 LT |
337 | * - we return -EAGAIN if we didn't find any matching key |
338 | * - we return -ENOKEY if we only found negative matching keys | |
664cceb0 | 339 | * - we propagate the possession attribute from the keyring ref to the key ref |
1da177e4 | 340 | */ |
664cceb0 DH |
341 | key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
342 | struct task_struct *context, | |
343 | struct key_type *type, | |
344 | const void *description, | |
345 | key_match_func_t match) | |
1da177e4 LT |
346 | { |
347 | struct { | |
76d8aeab | 348 | struct keyring_list *keylist; |
1da177e4 LT |
349 | int kix; |
350 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
351 | ||
352 | struct keyring_list *keylist; | |
353 | struct timespec now; | |
664cceb0 DH |
354 | unsigned long possessed; |
355 | struct key *keyring, *key; | |
356 | key_ref_t key_ref; | |
1da177e4 | 357 | long err; |
76d8aeab | 358 | int sp, kix; |
1da177e4 | 359 | |
664cceb0 DH |
360 | keyring = key_ref_to_ptr(keyring_ref); |
361 | possessed = is_key_possessed(keyring_ref); | |
1da177e4 LT |
362 | key_check(keyring); |
363 | ||
364 | /* top keyring must have search permission to begin the search */ | |
29db9190 DH |
365 | err = key_task_permission(keyring_ref, context, KEY_SEARCH); |
366 | if (err < 0) { | |
367 | key_ref = ERR_PTR(err); | |
1da177e4 | 368 | goto error; |
29db9190 | 369 | } |
1da177e4 | 370 | |
664cceb0 | 371 | key_ref = ERR_PTR(-ENOTDIR); |
1da177e4 LT |
372 | if (keyring->type != &key_type_keyring) |
373 | goto error; | |
374 | ||
664cceb0 DH |
375 | rcu_read_lock(); |
376 | ||
1da177e4 LT |
377 | now = current_kernel_time(); |
378 | err = -EAGAIN; | |
379 | sp = 0; | |
380 | ||
381 | /* start processing a new keyring */ | |
664cceb0 | 382 | descend: |
76d8aeab | 383 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
384 | goto not_this_keyring; |
385 | ||
76d8aeab | 386 | keylist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
387 | if (!keylist) |
388 | goto not_this_keyring; | |
389 | ||
390 | /* iterate through the keys in this keyring first */ | |
391 | for (kix = 0; kix < keylist->nkeys; kix++) { | |
392 | key = keylist->keys[kix]; | |
393 | ||
394 | /* ignore keys not of this type */ | |
395 | if (key->type != type) | |
396 | continue; | |
397 | ||
398 | /* skip revoked keys and expired keys */ | |
76d8aeab | 399 | if (test_bit(KEY_FLAG_REVOKED, &key->flags)) |
1da177e4 LT |
400 | continue; |
401 | ||
402 | if (key->expiry && now.tv_sec >= key->expiry) | |
403 | continue; | |
404 | ||
405 | /* keys that don't match */ | |
406 | if (!match(key, description)) | |
407 | continue; | |
408 | ||
409 | /* key must have search permissions */ | |
29db9190 DH |
410 | if (key_task_permission(make_key_ref(key, possessed), |
411 | context, KEY_SEARCH) < 0) | |
1da177e4 LT |
412 | continue; |
413 | ||
414 | /* we set a different error code if we find a negative key */ | |
76d8aeab | 415 | if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) { |
1da177e4 LT |
416 | err = -ENOKEY; |
417 | continue; | |
418 | } | |
419 | ||
420 | goto found; | |
421 | } | |
422 | ||
423 | /* search through the keyrings nested in this one */ | |
424 | kix = 0; | |
664cceb0 | 425 | ascend: |
76d8aeab | 426 | for (; kix < keylist->nkeys; kix++) { |
1da177e4 LT |
427 | key = keylist->keys[kix]; |
428 | if (key->type != &key_type_keyring) | |
76d8aeab | 429 | continue; |
1da177e4 LT |
430 | |
431 | /* recursively search nested keyrings | |
432 | * - only search keyrings for which we have search permission | |
433 | */ | |
434 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
76d8aeab | 435 | continue; |
1da177e4 | 436 | |
0f6ed7c2 DH |
437 | if (key_task_permission(make_key_ref(key, possessed), |
438 | context, KEY_SEARCH) < 0) | |
76d8aeab | 439 | continue; |
1da177e4 LT |
440 | |
441 | /* stack the current position */ | |
76d8aeab | 442 | stack[sp].keylist = keylist; |
1da177e4 LT |
443 | stack[sp].kix = kix; |
444 | sp++; | |
445 | ||
446 | /* begin again with the new keyring */ | |
447 | keyring = key; | |
448 | goto descend; | |
1da177e4 LT |
449 | } |
450 | ||
451 | /* the keyring we're looking at was disqualified or didn't contain a | |
452 | * matching key */ | |
664cceb0 | 453 | not_this_keyring: |
1da177e4 LT |
454 | if (sp > 0) { |
455 | /* resume the processing of a keyring higher up in the tree */ | |
456 | sp--; | |
76d8aeab | 457 | keylist = stack[sp].keylist; |
1da177e4 LT |
458 | kix = stack[sp].kix + 1; |
459 | goto ascend; | |
460 | } | |
461 | ||
664cceb0 DH |
462 | key_ref = ERR_PTR(err); |
463 | goto error_2; | |
1da177e4 LT |
464 | |
465 | /* we found a viable match */ | |
664cceb0 | 466 | found: |
1da177e4 | 467 | atomic_inc(&key->usage); |
1da177e4 | 468 | key_check(key); |
664cceb0 DH |
469 | key_ref = make_key_ref(key, possessed); |
470 | error_2: | |
76d8aeab | 471 | rcu_read_unlock(); |
664cceb0 DH |
472 | error: |
473 | return key_ref; | |
1da177e4 LT |
474 | |
475 | } /* end keyring_search_aux() */ | |
476 | ||
477 | /*****************************************************************************/ | |
478 | /* | |
479 | * search the supplied keyring tree for a key that matches the criterion | |
480 | * - perform a breadth-then-depth search up to the prescribed limit | |
481 | * - we only find keys on which we have search permission | |
482 | * - we readlock the keyrings as we search down the tree | |
483 | * - we return -EAGAIN if we didn't find any matching key | |
484 | * - we return -ENOKEY if we only found negative matching keys | |
485 | */ | |
664cceb0 DH |
486 | key_ref_t keyring_search(key_ref_t keyring, |
487 | struct key_type *type, | |
488 | const char *description) | |
1da177e4 | 489 | { |
3e30148c DH |
490 | if (!type->match) |
491 | return ERR_PTR(-ENOKEY); | |
492 | ||
493 | return keyring_search_aux(keyring, current, | |
494 | type, description, type->match); | |
1da177e4 LT |
495 | |
496 | } /* end keyring_search() */ | |
497 | ||
498 | EXPORT_SYMBOL(keyring_search); | |
499 | ||
500 | /*****************************************************************************/ | |
501 | /* | |
502 | * search the given keyring only (no recursion) | |
503 | * - keyring must be locked by caller | |
504 | */ | |
664cceb0 DH |
505 | key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
506 | const struct key_type *ktype, | |
507 | const char *description, | |
508 | key_perm_t perm) | |
1da177e4 LT |
509 | { |
510 | struct keyring_list *klist; | |
664cceb0 DH |
511 | unsigned long possessed; |
512 | struct key *keyring, *key; | |
1da177e4 LT |
513 | int loop; |
514 | ||
664cceb0 DH |
515 | keyring = key_ref_to_ptr(keyring_ref); |
516 | possessed = is_key_possessed(keyring_ref); | |
517 | ||
76d8aeab DH |
518 | rcu_read_lock(); |
519 | ||
520 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
521 | if (klist) { |
522 | for (loop = 0; loop < klist->nkeys; loop++) { | |
523 | key = klist->keys[loop]; | |
524 | ||
525 | if (key->type == ktype && | |
3e30148c DH |
526 | (!key->type->match || |
527 | key->type->match(key, description)) && | |
664cceb0 | 528 | key_permission(make_key_ref(key, possessed), |
db1d1d57 | 529 | perm) == 0 && |
76d8aeab | 530 | !test_bit(KEY_FLAG_REVOKED, &key->flags) |
1da177e4 LT |
531 | ) |
532 | goto found; | |
533 | } | |
534 | } | |
535 | ||
664cceb0 DH |
536 | rcu_read_unlock(); |
537 | return ERR_PTR(-ENOKEY); | |
1da177e4 LT |
538 | |
539 | found: | |
540 | atomic_inc(&key->usage); | |
76d8aeab | 541 | rcu_read_unlock(); |
664cceb0 | 542 | return make_key_ref(key, possessed); |
1da177e4 LT |
543 | |
544 | } /* end __keyring_search_one() */ | |
545 | ||
3e30148c DH |
546 | /*****************************************************************************/ |
547 | /* | |
548 | * search for an instantiation authorisation key matching a target key | |
549 | * - the RCU read lock must be held by the caller | |
550 | * - a target_id of zero specifies any valid token | |
551 | */ | |
552 | struct key *keyring_search_instkey(struct key *keyring, | |
553 | key_serial_t target_id) | |
554 | { | |
555 | struct request_key_auth *rka; | |
556 | struct keyring_list *klist; | |
557 | struct key *instkey; | |
558 | int loop; | |
559 | ||
560 | klist = rcu_dereference(keyring->payload.subscriptions); | |
561 | if (klist) { | |
562 | for (loop = 0; loop < klist->nkeys; loop++) { | |
563 | instkey = klist->keys[loop]; | |
564 | ||
565 | if (instkey->type != &key_type_request_key_auth) | |
566 | continue; | |
567 | ||
568 | rka = instkey->payload.data; | |
569 | if (target_id && rka->target_key->serial != target_id) | |
570 | continue; | |
571 | ||
572 | /* the auth key is revoked during instantiation */ | |
573 | if (!test_bit(KEY_FLAG_REVOKED, &instkey->flags)) | |
574 | goto found; | |
575 | ||
576 | instkey = ERR_PTR(-EKEYREVOKED); | |
577 | goto error; | |
578 | } | |
579 | } | |
580 | ||
581 | instkey = ERR_PTR(-EACCES); | |
582 | goto error; | |
583 | ||
584 | found: | |
585 | atomic_inc(&instkey->usage); | |
586 | error: | |
587 | return instkey; | |
588 | ||
589 | } /* end keyring_search_instkey() */ | |
590 | ||
1da177e4 LT |
591 | /*****************************************************************************/ |
592 | /* | |
593 | * find a keyring with the specified name | |
594 | * - all named keyrings are searched | |
595 | * - only find keyrings with search permission for the process | |
596 | * - only find keyrings with a serial number greater than the one specified | |
597 | */ | |
598 | struct key *find_keyring_by_name(const char *name, key_serial_t bound) | |
599 | { | |
600 | struct key *keyring; | |
601 | int bucket; | |
602 | ||
603 | keyring = ERR_PTR(-EINVAL); | |
604 | if (!name) | |
605 | goto error; | |
606 | ||
607 | bucket = keyring_hash(name); | |
608 | ||
609 | read_lock(&keyring_name_lock); | |
610 | ||
611 | if (keyring_name_hash[bucket].next) { | |
612 | /* search this hash bucket for a keyring with a matching name | |
613 | * that's readable and that hasn't been revoked */ | |
614 | list_for_each_entry(keyring, | |
615 | &keyring_name_hash[bucket], | |
616 | type_data.link | |
617 | ) { | |
76d8aeab | 618 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
619 | continue; |
620 | ||
621 | if (strcmp(keyring->description, name) != 0) | |
622 | continue; | |
623 | ||
0f6ed7c2 DH |
624 | if (key_permission(make_key_ref(keyring, 0), |
625 | KEY_SEARCH) < 0) | |
1da177e4 LT |
626 | continue; |
627 | ||
628 | /* found a potential candidate, but we still need to | |
629 | * check the serial number */ | |
630 | if (keyring->serial <= bound) | |
631 | continue; | |
632 | ||
633 | /* we've got a match */ | |
634 | atomic_inc(&keyring->usage); | |
635 | read_unlock(&keyring_name_lock); | |
636 | goto error; | |
637 | } | |
638 | } | |
639 | ||
640 | read_unlock(&keyring_name_lock); | |
641 | keyring = ERR_PTR(-ENOKEY); | |
642 | ||
643 | error: | |
644 | return keyring; | |
645 | ||
646 | } /* end find_keyring_by_name() */ | |
647 | ||
648 | /*****************************************************************************/ | |
649 | /* | |
650 | * see if a cycle will will be created by inserting acyclic tree B in acyclic | |
651 | * tree A at the topmost level (ie: as a direct child of A) | |
652 | * - since we are adding B to A at the top level, checking for cycles should | |
653 | * just be a matter of seeing if node A is somewhere in tree B | |
654 | */ | |
655 | static int keyring_detect_cycle(struct key *A, struct key *B) | |
656 | { | |
657 | struct { | |
76d8aeab | 658 | struct keyring_list *keylist; |
1da177e4 LT |
659 | int kix; |
660 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
661 | ||
662 | struct keyring_list *keylist; | |
663 | struct key *subtree, *key; | |
664 | int sp, kix, ret; | |
665 | ||
76d8aeab DH |
666 | rcu_read_lock(); |
667 | ||
1da177e4 LT |
668 | ret = -EDEADLK; |
669 | if (A == B) | |
76d8aeab | 670 | goto cycle_detected; |
1da177e4 LT |
671 | |
672 | subtree = B; | |
673 | sp = 0; | |
674 | ||
675 | /* start processing a new keyring */ | |
676 | descend: | |
76d8aeab | 677 | if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
1da177e4 LT |
678 | goto not_this_keyring; |
679 | ||
76d8aeab | 680 | keylist = rcu_dereference(subtree->payload.subscriptions); |
1da177e4 LT |
681 | if (!keylist) |
682 | goto not_this_keyring; | |
683 | kix = 0; | |
684 | ||
685 | ascend: | |
686 | /* iterate through the remaining keys in this keyring */ | |
687 | for (; kix < keylist->nkeys; kix++) { | |
688 | key = keylist->keys[kix]; | |
689 | ||
690 | if (key == A) | |
691 | goto cycle_detected; | |
692 | ||
693 | /* recursively check nested keyrings */ | |
694 | if (key->type == &key_type_keyring) { | |
695 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
696 | goto too_deep; | |
697 | ||
698 | /* stack the current position */ | |
76d8aeab | 699 | stack[sp].keylist = keylist; |
1da177e4 LT |
700 | stack[sp].kix = kix; |
701 | sp++; | |
702 | ||
703 | /* begin again with the new keyring */ | |
704 | subtree = key; | |
705 | goto descend; | |
706 | } | |
707 | } | |
708 | ||
709 | /* the keyring we're looking at was disqualified or didn't contain a | |
710 | * matching key */ | |
711 | not_this_keyring: | |
1da177e4 LT |
712 | if (sp > 0) { |
713 | /* resume the checking of a keyring higher up in the tree */ | |
714 | sp--; | |
76d8aeab | 715 | keylist = stack[sp].keylist; |
1da177e4 LT |
716 | kix = stack[sp].kix + 1; |
717 | goto ascend; | |
718 | } | |
719 | ||
720 | ret = 0; /* no cycles detected */ | |
721 | ||
722 | error: | |
76d8aeab | 723 | rcu_read_unlock(); |
1da177e4 LT |
724 | return ret; |
725 | ||
726 | too_deep: | |
727 | ret = -ELOOP; | |
76d8aeab DH |
728 | goto error; |
729 | ||
1da177e4 LT |
730 | cycle_detected: |
731 | ret = -EDEADLK; | |
1da177e4 LT |
732 | goto error; |
733 | ||
734 | } /* end keyring_detect_cycle() */ | |
735 | ||
76d8aeab DH |
736 | /*****************************************************************************/ |
737 | /* | |
738 | * dispose of a keyring list after the RCU grace period | |
739 | */ | |
740 | static void keyring_link_rcu_disposal(struct rcu_head *rcu) | |
741 | { | |
742 | struct keyring_list *klist = | |
743 | container_of(rcu, struct keyring_list, rcu); | |
744 | ||
745 | kfree(klist); | |
746 | ||
747 | } /* end keyring_link_rcu_disposal() */ | |
748 | ||
1da177e4 LT |
749 | /*****************************************************************************/ |
750 | /* | |
751 | * link a key into to a keyring | |
76d8aeab | 752 | * - must be called with the keyring's semaphore write-locked |
1da177e4 LT |
753 | */ |
754 | int __key_link(struct key *keyring, struct key *key) | |
755 | { | |
756 | struct keyring_list *klist, *nklist; | |
757 | unsigned max; | |
758 | size_t size; | |
759 | int ret; | |
760 | ||
761 | ret = -EKEYREVOKED; | |
76d8aeab | 762 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
763 | goto error; |
764 | ||
765 | ret = -ENOTDIR; | |
766 | if (keyring->type != &key_type_keyring) | |
767 | goto error; | |
768 | ||
769 | /* serialise link/link calls to prevent parallel calls causing a | |
770 | * cycle when applied to two keyring in opposite orders */ | |
771 | down_write(&keyring_serialise_link_sem); | |
772 | ||
773 | /* check that we aren't going to create a cycle adding one keyring to | |
774 | * another */ | |
775 | if (key->type == &key_type_keyring) { | |
776 | ret = keyring_detect_cycle(keyring, key); | |
777 | if (ret < 0) | |
778 | goto error2; | |
779 | } | |
780 | ||
781 | /* check that we aren't going to overrun the user's quota */ | |
782 | ret = key_payload_reserve(keyring, | |
783 | keyring->datalen + KEYQUOTA_LINK_BYTES); | |
784 | if (ret < 0) | |
785 | goto error2; | |
786 | ||
787 | klist = keyring->payload.subscriptions; | |
788 | ||
789 | if (klist && klist->nkeys < klist->maxkeys) { | |
790 | /* there's sufficient slack space to add directly */ | |
791 | atomic_inc(&key->usage); | |
792 | ||
76d8aeab DH |
793 | klist->keys[klist->nkeys] = key; |
794 | smp_wmb(); | |
795 | klist->nkeys++; | |
796 | smp_wmb(); | |
1da177e4 LT |
797 | |
798 | ret = 0; | |
799 | } | |
800 | else { | |
801 | /* grow the key list */ | |
802 | max = 4; | |
803 | if (klist) | |
804 | max += klist->maxkeys; | |
805 | ||
806 | ret = -ENFILE; | |
76d8aeab DH |
807 | if (max > 65535) |
808 | goto error3; | |
a4014d8f | 809 | size = sizeof(*klist) + sizeof(struct key *) * max; |
1da177e4 LT |
810 | if (size > PAGE_SIZE) |
811 | goto error3; | |
812 | ||
813 | ret = -ENOMEM; | |
814 | nklist = kmalloc(size, GFP_KERNEL); | |
815 | if (!nklist) | |
816 | goto error3; | |
817 | nklist->maxkeys = max; | |
818 | nklist->nkeys = 0; | |
819 | ||
820 | if (klist) { | |
821 | nklist->nkeys = klist->nkeys; | |
822 | memcpy(nklist->keys, | |
823 | klist->keys, | |
824 | sizeof(struct key *) * klist->nkeys); | |
825 | } | |
826 | ||
827 | /* add the key into the new space */ | |
828 | atomic_inc(&key->usage); | |
1da177e4 | 829 | nklist->keys[nklist->nkeys++] = key; |
76d8aeab DH |
830 | |
831 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); | |
1da177e4 LT |
832 | |
833 | /* dispose of the old keyring list */ | |
76d8aeab DH |
834 | if (klist) |
835 | call_rcu(&klist->rcu, keyring_link_rcu_disposal); | |
1da177e4 LT |
836 | |
837 | ret = 0; | |
838 | } | |
839 | ||
840 | error2: | |
841 | up_write(&keyring_serialise_link_sem); | |
842 | error: | |
843 | return ret; | |
844 | ||
845 | error3: | |
846 | /* undo the quota changes */ | |
847 | key_payload_reserve(keyring, | |
848 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
849 | goto error2; | |
850 | ||
851 | } /* end __key_link() */ | |
852 | ||
853 | /*****************************************************************************/ | |
854 | /* | |
855 | * link a key to a keyring | |
856 | */ | |
857 | int key_link(struct key *keyring, struct key *key) | |
858 | { | |
859 | int ret; | |
860 | ||
861 | key_check(keyring); | |
862 | key_check(key); | |
863 | ||
864 | down_write(&keyring->sem); | |
865 | ret = __key_link(keyring, key); | |
866 | up_write(&keyring->sem); | |
867 | ||
868 | return ret; | |
869 | ||
870 | } /* end key_link() */ | |
871 | ||
872 | EXPORT_SYMBOL(key_link); | |
873 | ||
76d8aeab DH |
874 | /*****************************************************************************/ |
875 | /* | |
876 | * dispose of a keyring list after the RCU grace period, freeing the unlinked | |
877 | * key | |
878 | */ | |
879 | static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) | |
880 | { | |
881 | struct keyring_list *klist = | |
882 | container_of(rcu, struct keyring_list, rcu); | |
883 | ||
884 | key_put(klist->keys[klist->delkey]); | |
885 | kfree(klist); | |
886 | ||
887 | } /* end keyring_unlink_rcu_disposal() */ | |
888 | ||
1da177e4 LT |
889 | /*****************************************************************************/ |
890 | /* | |
891 | * unlink the first link to a key from a keyring | |
892 | */ | |
893 | int key_unlink(struct key *keyring, struct key *key) | |
894 | { | |
76d8aeab | 895 | struct keyring_list *klist, *nklist; |
1da177e4 LT |
896 | int loop, ret; |
897 | ||
898 | key_check(keyring); | |
899 | key_check(key); | |
900 | ||
901 | ret = -ENOTDIR; | |
902 | if (keyring->type != &key_type_keyring) | |
903 | goto error; | |
904 | ||
905 | down_write(&keyring->sem); | |
906 | ||
907 | klist = keyring->payload.subscriptions; | |
908 | if (klist) { | |
909 | /* search the keyring for the key */ | |
910 | for (loop = 0; loop < klist->nkeys; loop++) | |
911 | if (klist->keys[loop] == key) | |
912 | goto key_is_present; | |
913 | } | |
914 | ||
915 | up_write(&keyring->sem); | |
916 | ret = -ENOENT; | |
917 | goto error; | |
918 | ||
76d8aeab DH |
919 | key_is_present: |
920 | /* we need to copy the key list for RCU purposes */ | |
a4014d8f DH |
921 | nklist = kmalloc(sizeof(*klist) + |
922 | sizeof(struct key *) * klist->maxkeys, | |
76d8aeab DH |
923 | GFP_KERNEL); |
924 | if (!nklist) | |
925 | goto nomem; | |
926 | nklist->maxkeys = klist->maxkeys; | |
927 | nklist->nkeys = klist->nkeys - 1; | |
928 | ||
929 | if (loop > 0) | |
930 | memcpy(&nklist->keys[0], | |
931 | &klist->keys[0], | |
a4014d8f | 932 | loop * sizeof(struct key *)); |
76d8aeab DH |
933 | |
934 | if (loop < nklist->nkeys) | |
935 | memcpy(&nklist->keys[loop], | |
936 | &klist->keys[loop + 1], | |
a4014d8f | 937 | (nklist->nkeys - loop) * sizeof(struct key *)); |
76d8aeab | 938 | |
1da177e4 LT |
939 | /* adjust the user's quota */ |
940 | key_payload_reserve(keyring, | |
941 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
942 | ||
76d8aeab | 943 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
1da177e4 | 944 | |
76d8aeab | 945 | up_write(&keyring->sem); |
1da177e4 | 946 | |
76d8aeab DH |
947 | /* schedule for later cleanup */ |
948 | klist->delkey = loop; | |
949 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
1da177e4 | 950 | |
1da177e4 LT |
951 | ret = 0; |
952 | ||
76d8aeab | 953 | error: |
1da177e4 | 954 | return ret; |
76d8aeab DH |
955 | nomem: |
956 | ret = -ENOMEM; | |
957 | up_write(&keyring->sem); | |
958 | goto error; | |
1da177e4 LT |
959 | |
960 | } /* end key_unlink() */ | |
961 | ||
962 | EXPORT_SYMBOL(key_unlink); | |
963 | ||
76d8aeab DH |
964 | /*****************************************************************************/ |
965 | /* | |
966 | * dispose of a keyring list after the RCU grace period, releasing the keys it | |
967 | * links to | |
968 | */ | |
969 | static void keyring_clear_rcu_disposal(struct rcu_head *rcu) | |
970 | { | |
971 | struct keyring_list *klist; | |
972 | int loop; | |
973 | ||
974 | klist = container_of(rcu, struct keyring_list, rcu); | |
975 | ||
976 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
977 | key_put(klist->keys[loop]); | |
978 | ||
979 | kfree(klist); | |
980 | ||
981 | } /* end keyring_clear_rcu_disposal() */ | |
982 | ||
1da177e4 LT |
983 | /*****************************************************************************/ |
984 | /* | |
985 | * clear the specified process keyring | |
986 | * - implements keyctl(KEYCTL_CLEAR) | |
987 | */ | |
988 | int keyring_clear(struct key *keyring) | |
989 | { | |
990 | struct keyring_list *klist; | |
76d8aeab | 991 | int ret; |
1da177e4 LT |
992 | |
993 | ret = -ENOTDIR; | |
994 | if (keyring->type == &key_type_keyring) { | |
995 | /* detach the pointer block with the locks held */ | |
996 | down_write(&keyring->sem); | |
997 | ||
998 | klist = keyring->payload.subscriptions; | |
999 | if (klist) { | |
1000 | /* adjust the quota */ | |
1001 | key_payload_reserve(keyring, | |
1002 | sizeof(struct keyring_list)); | |
1003 | ||
76d8aeab DH |
1004 | rcu_assign_pointer(keyring->payload.subscriptions, |
1005 | NULL); | |
1da177e4 LT |
1006 | } |
1007 | ||
1008 | up_write(&keyring->sem); | |
1009 | ||
1010 | /* free the keys after the locks have been dropped */ | |
76d8aeab DH |
1011 | if (klist) |
1012 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1da177e4 LT |
1013 | |
1014 | ret = 0; | |
1015 | } | |
1016 | ||
1017 | return ret; | |
1018 | ||
1019 | } /* end keyring_clear() */ | |
1020 | ||
1021 | EXPORT_SYMBOL(keyring_clear); |