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