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