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 | */ | |
1ae8f407 | 71 | static DECLARE_RWSEM(keyring_serialise_link_sem); |
1da177e4 LT |
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, | |
7e047ef5 | 243 | struct task_struct *ctx, unsigned long flags, |
d720024e | 244 | struct key *dest) |
1da177e4 LT |
245 | { |
246 | struct key *keyring; | |
247 | int ret; | |
248 | ||
249 | keyring = key_alloc(&key_type_keyring, description, | |
d720024e | 250 | uid, gid, ctx, |
29db9190 | 251 | (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, |
7e047ef5 | 252 | flags); |
1da177e4 LT |
253 | |
254 | if (!IS_ERR(keyring)) { | |
3e30148c | 255 | ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); |
1da177e4 LT |
256 | if (ret < 0) { |
257 | key_put(keyring); | |
258 | keyring = ERR_PTR(ret); | |
259 | } | |
260 | } | |
261 | ||
262 | return keyring; | |
263 | ||
264 | } /* end keyring_alloc() */ | |
265 | ||
266 | /*****************************************************************************/ | |
267 | /* | |
268 | * search the supplied keyring tree for a key that matches the criterion | |
269 | * - perform a breadth-then-depth search up to the prescribed limit | |
270 | * - we only find keys on which we have search permission | |
271 | * - we use the supplied match function to see if the description (or other | |
272 | * feature of interest) matches | |
3e30148c | 273 | * - we rely on RCU to prevent the keyring lists from disappearing on us |
1da177e4 LT |
274 | * - we return -EAGAIN if we didn't find any matching key |
275 | * - we return -ENOKEY if we only found negative matching keys | |
664cceb0 | 276 | * - we propagate the possession attribute from the keyring ref to the key ref |
1da177e4 | 277 | */ |
664cceb0 DH |
278 | key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
279 | struct task_struct *context, | |
280 | struct key_type *type, | |
281 | const void *description, | |
282 | key_match_func_t match) | |
1da177e4 LT |
283 | { |
284 | struct { | |
76d8aeab | 285 | struct keyring_list *keylist; |
1da177e4 LT |
286 | int kix; |
287 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
288 | ||
289 | struct keyring_list *keylist; | |
290 | struct timespec now; | |
664cceb0 DH |
291 | unsigned long possessed; |
292 | struct key *keyring, *key; | |
293 | key_ref_t key_ref; | |
1da177e4 | 294 | long err; |
76d8aeab | 295 | int sp, kix; |
1da177e4 | 296 | |
664cceb0 DH |
297 | keyring = key_ref_to_ptr(keyring_ref); |
298 | possessed = is_key_possessed(keyring_ref); | |
1da177e4 LT |
299 | key_check(keyring); |
300 | ||
301 | /* top keyring must have search permission to begin the search */ | |
29db9190 DH |
302 | err = key_task_permission(keyring_ref, context, KEY_SEARCH); |
303 | if (err < 0) { | |
304 | key_ref = ERR_PTR(err); | |
1da177e4 | 305 | goto error; |
29db9190 | 306 | } |
1da177e4 | 307 | |
664cceb0 | 308 | key_ref = ERR_PTR(-ENOTDIR); |
1da177e4 LT |
309 | if (keyring->type != &key_type_keyring) |
310 | goto error; | |
311 | ||
664cceb0 DH |
312 | rcu_read_lock(); |
313 | ||
1da177e4 LT |
314 | now = current_kernel_time(); |
315 | err = -EAGAIN; | |
316 | sp = 0; | |
317 | ||
318 | /* start processing a new keyring */ | |
664cceb0 | 319 | descend: |
76d8aeab | 320 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
321 | goto not_this_keyring; |
322 | ||
76d8aeab | 323 | keylist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
324 | if (!keylist) |
325 | goto not_this_keyring; | |
326 | ||
327 | /* iterate through the keys in this keyring first */ | |
328 | for (kix = 0; kix < keylist->nkeys; kix++) { | |
329 | key = keylist->keys[kix]; | |
330 | ||
331 | /* ignore keys not of this type */ | |
332 | if (key->type != type) | |
333 | continue; | |
334 | ||
335 | /* skip revoked keys and expired keys */ | |
76d8aeab | 336 | if (test_bit(KEY_FLAG_REVOKED, &key->flags)) |
1da177e4 LT |
337 | continue; |
338 | ||
339 | if (key->expiry && now.tv_sec >= key->expiry) | |
340 | continue; | |
341 | ||
342 | /* keys that don't match */ | |
343 | if (!match(key, description)) | |
344 | continue; | |
345 | ||
346 | /* key must have search permissions */ | |
29db9190 DH |
347 | if (key_task_permission(make_key_ref(key, possessed), |
348 | context, KEY_SEARCH) < 0) | |
1da177e4 LT |
349 | continue; |
350 | ||
351 | /* we set a different error code if we find a negative key */ | |
76d8aeab | 352 | if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) { |
1da177e4 LT |
353 | err = -ENOKEY; |
354 | continue; | |
355 | } | |
356 | ||
357 | goto found; | |
358 | } | |
359 | ||
360 | /* search through the keyrings nested in this one */ | |
361 | kix = 0; | |
664cceb0 | 362 | ascend: |
76d8aeab | 363 | for (; kix < keylist->nkeys; kix++) { |
1da177e4 LT |
364 | key = keylist->keys[kix]; |
365 | if (key->type != &key_type_keyring) | |
76d8aeab | 366 | continue; |
1da177e4 LT |
367 | |
368 | /* recursively search nested keyrings | |
369 | * - only search keyrings for which we have search permission | |
370 | */ | |
371 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
76d8aeab | 372 | continue; |
1da177e4 | 373 | |
0f6ed7c2 DH |
374 | if (key_task_permission(make_key_ref(key, possessed), |
375 | context, KEY_SEARCH) < 0) | |
76d8aeab | 376 | continue; |
1da177e4 LT |
377 | |
378 | /* stack the current position */ | |
76d8aeab | 379 | stack[sp].keylist = keylist; |
1da177e4 LT |
380 | stack[sp].kix = kix; |
381 | sp++; | |
382 | ||
383 | /* begin again with the new keyring */ | |
384 | keyring = key; | |
385 | goto descend; | |
1da177e4 LT |
386 | } |
387 | ||
388 | /* the keyring we're looking at was disqualified or didn't contain a | |
389 | * matching key */ | |
664cceb0 | 390 | not_this_keyring: |
1da177e4 LT |
391 | if (sp > 0) { |
392 | /* resume the processing of a keyring higher up in the tree */ | |
393 | sp--; | |
76d8aeab | 394 | keylist = stack[sp].keylist; |
1da177e4 LT |
395 | kix = stack[sp].kix + 1; |
396 | goto ascend; | |
397 | } | |
398 | ||
664cceb0 DH |
399 | key_ref = ERR_PTR(err); |
400 | goto error_2; | |
1da177e4 LT |
401 | |
402 | /* we found a viable match */ | |
664cceb0 | 403 | found: |
1da177e4 | 404 | atomic_inc(&key->usage); |
1da177e4 | 405 | key_check(key); |
664cceb0 DH |
406 | key_ref = make_key_ref(key, possessed); |
407 | error_2: | |
76d8aeab | 408 | rcu_read_unlock(); |
664cceb0 DH |
409 | error: |
410 | return key_ref; | |
1da177e4 LT |
411 | |
412 | } /* end keyring_search_aux() */ | |
413 | ||
414 | /*****************************************************************************/ | |
415 | /* | |
416 | * search the supplied keyring tree for a key that matches the criterion | |
417 | * - perform a breadth-then-depth search up to the prescribed limit | |
418 | * - we only find keys on which we have search permission | |
419 | * - we readlock the keyrings as we search down the tree | |
420 | * - we return -EAGAIN if we didn't find any matching key | |
421 | * - we return -ENOKEY if we only found negative matching keys | |
422 | */ | |
664cceb0 DH |
423 | key_ref_t keyring_search(key_ref_t keyring, |
424 | struct key_type *type, | |
425 | const char *description) | |
1da177e4 | 426 | { |
3e30148c DH |
427 | if (!type->match) |
428 | return ERR_PTR(-ENOKEY); | |
429 | ||
430 | return keyring_search_aux(keyring, current, | |
431 | type, description, type->match); | |
1da177e4 LT |
432 | |
433 | } /* end keyring_search() */ | |
434 | ||
435 | EXPORT_SYMBOL(keyring_search); | |
436 | ||
437 | /*****************************************************************************/ | |
438 | /* | |
439 | * search the given keyring only (no recursion) | |
440 | * - keyring must be locked by caller | |
c3a9d654 | 441 | * - caller must guarantee that the keyring is a keyring |
1da177e4 | 442 | */ |
664cceb0 DH |
443 | key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
444 | const struct key_type *ktype, | |
445 | const char *description, | |
446 | key_perm_t perm) | |
1da177e4 LT |
447 | { |
448 | struct keyring_list *klist; | |
664cceb0 DH |
449 | unsigned long possessed; |
450 | struct key *keyring, *key; | |
1da177e4 LT |
451 | int loop; |
452 | ||
664cceb0 DH |
453 | keyring = key_ref_to_ptr(keyring_ref); |
454 | possessed = is_key_possessed(keyring_ref); | |
455 | ||
76d8aeab DH |
456 | rcu_read_lock(); |
457 | ||
458 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
459 | if (klist) { |
460 | for (loop = 0; loop < klist->nkeys; loop++) { | |
461 | key = klist->keys[loop]; | |
462 | ||
463 | if (key->type == ktype && | |
3e30148c DH |
464 | (!key->type->match || |
465 | key->type->match(key, description)) && | |
664cceb0 | 466 | key_permission(make_key_ref(key, possessed), |
db1d1d57 | 467 | perm) == 0 && |
76d8aeab | 468 | !test_bit(KEY_FLAG_REVOKED, &key->flags) |
1da177e4 LT |
469 | ) |
470 | goto found; | |
471 | } | |
472 | } | |
473 | ||
664cceb0 DH |
474 | rcu_read_unlock(); |
475 | return ERR_PTR(-ENOKEY); | |
1da177e4 LT |
476 | |
477 | found: | |
478 | atomic_inc(&key->usage); | |
76d8aeab | 479 | rcu_read_unlock(); |
664cceb0 | 480 | return make_key_ref(key, possessed); |
1da177e4 LT |
481 | |
482 | } /* end __keyring_search_one() */ | |
483 | ||
484 | /*****************************************************************************/ | |
485 | /* | |
486 | * find a keyring with the specified name | |
487 | * - all named keyrings are searched | |
488 | * - only find keyrings with search permission for the process | |
489 | * - only find keyrings with a serial number greater than the one specified | |
490 | */ | |
491 | struct key *find_keyring_by_name(const char *name, key_serial_t bound) | |
492 | { | |
493 | struct key *keyring; | |
494 | int bucket; | |
495 | ||
496 | keyring = ERR_PTR(-EINVAL); | |
497 | if (!name) | |
498 | goto error; | |
499 | ||
500 | bucket = keyring_hash(name); | |
501 | ||
502 | read_lock(&keyring_name_lock); | |
503 | ||
504 | if (keyring_name_hash[bucket].next) { | |
505 | /* search this hash bucket for a keyring with a matching name | |
506 | * that's readable and that hasn't been revoked */ | |
507 | list_for_each_entry(keyring, | |
508 | &keyring_name_hash[bucket], | |
509 | type_data.link | |
510 | ) { | |
76d8aeab | 511 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
512 | continue; |
513 | ||
514 | if (strcmp(keyring->description, name) != 0) | |
515 | continue; | |
516 | ||
0f6ed7c2 DH |
517 | if (key_permission(make_key_ref(keyring, 0), |
518 | KEY_SEARCH) < 0) | |
1da177e4 LT |
519 | continue; |
520 | ||
521 | /* found a potential candidate, but we still need to | |
522 | * check the serial number */ | |
523 | if (keyring->serial <= bound) | |
524 | continue; | |
525 | ||
526 | /* we've got a match */ | |
527 | atomic_inc(&keyring->usage); | |
528 | read_unlock(&keyring_name_lock); | |
529 | goto error; | |
530 | } | |
531 | } | |
532 | ||
533 | read_unlock(&keyring_name_lock); | |
534 | keyring = ERR_PTR(-ENOKEY); | |
535 | ||
536 | error: | |
537 | return keyring; | |
538 | ||
539 | } /* end find_keyring_by_name() */ | |
540 | ||
541 | /*****************************************************************************/ | |
542 | /* | |
543 | * see if a cycle will will be created by inserting acyclic tree B in acyclic | |
544 | * tree A at the topmost level (ie: as a direct child of A) | |
545 | * - since we are adding B to A at the top level, checking for cycles should | |
546 | * just be a matter of seeing if node A is somewhere in tree B | |
547 | */ | |
548 | static int keyring_detect_cycle(struct key *A, struct key *B) | |
549 | { | |
550 | struct { | |
76d8aeab | 551 | struct keyring_list *keylist; |
1da177e4 LT |
552 | int kix; |
553 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
554 | ||
555 | struct keyring_list *keylist; | |
556 | struct key *subtree, *key; | |
557 | int sp, kix, ret; | |
558 | ||
76d8aeab DH |
559 | rcu_read_lock(); |
560 | ||
1da177e4 LT |
561 | ret = -EDEADLK; |
562 | if (A == B) | |
76d8aeab | 563 | goto cycle_detected; |
1da177e4 LT |
564 | |
565 | subtree = B; | |
566 | sp = 0; | |
567 | ||
568 | /* start processing a new keyring */ | |
569 | descend: | |
76d8aeab | 570 | if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
1da177e4 LT |
571 | goto not_this_keyring; |
572 | ||
76d8aeab | 573 | keylist = rcu_dereference(subtree->payload.subscriptions); |
1da177e4 LT |
574 | if (!keylist) |
575 | goto not_this_keyring; | |
576 | kix = 0; | |
577 | ||
578 | ascend: | |
579 | /* iterate through the remaining keys in this keyring */ | |
580 | for (; kix < keylist->nkeys; kix++) { | |
581 | key = keylist->keys[kix]; | |
582 | ||
583 | if (key == A) | |
584 | goto cycle_detected; | |
585 | ||
586 | /* recursively check nested keyrings */ | |
587 | if (key->type == &key_type_keyring) { | |
588 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
589 | goto too_deep; | |
590 | ||
591 | /* stack the current position */ | |
76d8aeab | 592 | stack[sp].keylist = keylist; |
1da177e4 LT |
593 | stack[sp].kix = kix; |
594 | sp++; | |
595 | ||
596 | /* begin again with the new keyring */ | |
597 | subtree = key; | |
598 | goto descend; | |
599 | } | |
600 | } | |
601 | ||
602 | /* the keyring we're looking at was disqualified or didn't contain a | |
603 | * matching key */ | |
604 | not_this_keyring: | |
1da177e4 LT |
605 | if (sp > 0) { |
606 | /* resume the checking of a keyring higher up in the tree */ | |
607 | sp--; | |
76d8aeab | 608 | keylist = stack[sp].keylist; |
1da177e4 LT |
609 | kix = stack[sp].kix + 1; |
610 | goto ascend; | |
611 | } | |
612 | ||
613 | ret = 0; /* no cycles detected */ | |
614 | ||
615 | error: | |
76d8aeab | 616 | rcu_read_unlock(); |
1da177e4 LT |
617 | return ret; |
618 | ||
619 | too_deep: | |
620 | ret = -ELOOP; | |
76d8aeab DH |
621 | goto error; |
622 | ||
1da177e4 LT |
623 | cycle_detected: |
624 | ret = -EDEADLK; | |
1da177e4 LT |
625 | goto error; |
626 | ||
627 | } /* end keyring_detect_cycle() */ | |
628 | ||
76d8aeab DH |
629 | /*****************************************************************************/ |
630 | /* | |
631 | * dispose of a keyring list after the RCU grace period | |
632 | */ | |
633 | static void keyring_link_rcu_disposal(struct rcu_head *rcu) | |
634 | { | |
635 | struct keyring_list *klist = | |
636 | container_of(rcu, struct keyring_list, rcu); | |
637 | ||
638 | kfree(klist); | |
639 | ||
640 | } /* end keyring_link_rcu_disposal() */ | |
641 | ||
cab8eb59 DH |
642 | /*****************************************************************************/ |
643 | /* | |
644 | * dispose of a keyring list after the RCU grace period, freeing the unlinked | |
645 | * key | |
646 | */ | |
647 | static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) | |
648 | { | |
649 | struct keyring_list *klist = | |
650 | container_of(rcu, struct keyring_list, rcu); | |
651 | ||
652 | key_put(klist->keys[klist->delkey]); | |
653 | kfree(klist); | |
654 | ||
655 | } /* end keyring_unlink_rcu_disposal() */ | |
656 | ||
1da177e4 LT |
657 | /*****************************************************************************/ |
658 | /* | |
659 | * link a key into to a keyring | |
76d8aeab | 660 | * - must be called with the keyring's semaphore write-locked |
cab8eb59 | 661 | * - discard already extant link to matching key if there is one |
1da177e4 LT |
662 | */ |
663 | int __key_link(struct key *keyring, struct key *key) | |
664 | { | |
665 | struct keyring_list *klist, *nklist; | |
666 | unsigned max; | |
667 | size_t size; | |
cab8eb59 | 668 | int loop, ret; |
1da177e4 LT |
669 | |
670 | ret = -EKEYREVOKED; | |
76d8aeab | 671 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
672 | goto error; |
673 | ||
674 | ret = -ENOTDIR; | |
675 | if (keyring->type != &key_type_keyring) | |
676 | goto error; | |
677 | ||
678 | /* serialise link/link calls to prevent parallel calls causing a | |
679 | * cycle when applied to two keyring in opposite orders */ | |
680 | down_write(&keyring_serialise_link_sem); | |
681 | ||
682 | /* check that we aren't going to create a cycle adding one keyring to | |
683 | * another */ | |
684 | if (key->type == &key_type_keyring) { | |
685 | ret = keyring_detect_cycle(keyring, key); | |
686 | if (ret < 0) | |
687 | goto error2; | |
688 | } | |
689 | ||
cab8eb59 DH |
690 | /* see if there's a matching key we can displace */ |
691 | klist = keyring->payload.subscriptions; | |
692 | ||
693 | if (klist && klist->nkeys > 0) { | |
694 | struct key_type *type = key->type; | |
695 | ||
696 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { | |
697 | if (klist->keys[loop]->type == type && | |
698 | strcmp(klist->keys[loop]->description, | |
699 | key->description) == 0 | |
700 | ) { | |
701 | /* found a match - replace with new key */ | |
702 | size = sizeof(struct key *) * klist->maxkeys; | |
703 | size += sizeof(*klist); | |
704 | BUG_ON(size > PAGE_SIZE); | |
705 | ||
706 | ret = -ENOMEM; | |
707 | nklist = kmalloc(size, GFP_KERNEL); | |
708 | if (!nklist) | |
709 | goto error2; | |
710 | ||
711 | memcpy(nklist, klist, size); | |
712 | ||
713 | /* replace matched key */ | |
714 | atomic_inc(&key->usage); | |
715 | nklist->keys[loop] = key; | |
716 | ||
717 | rcu_assign_pointer( | |
718 | keyring->payload.subscriptions, | |
719 | nklist); | |
720 | ||
721 | /* dispose of the old keyring list and the | |
722 | * displaced key */ | |
723 | klist->delkey = loop; | |
724 | call_rcu(&klist->rcu, | |
725 | keyring_unlink_rcu_disposal); | |
726 | ||
727 | goto done; | |
728 | } | |
729 | } | |
730 | } | |
731 | ||
1da177e4 LT |
732 | /* check that we aren't going to overrun the user's quota */ |
733 | ret = key_payload_reserve(keyring, | |
734 | keyring->datalen + KEYQUOTA_LINK_BYTES); | |
735 | if (ret < 0) | |
736 | goto error2; | |
737 | ||
738 | klist = keyring->payload.subscriptions; | |
739 | ||
740 | if (klist && klist->nkeys < klist->maxkeys) { | |
741 | /* there's sufficient slack space to add directly */ | |
742 | atomic_inc(&key->usage); | |
743 | ||
76d8aeab DH |
744 | klist->keys[klist->nkeys] = key; |
745 | smp_wmb(); | |
746 | klist->nkeys++; | |
747 | smp_wmb(); | |
1da177e4 LT |
748 | } |
749 | else { | |
750 | /* grow the key list */ | |
751 | max = 4; | |
752 | if (klist) | |
753 | max += klist->maxkeys; | |
754 | ||
755 | ret = -ENFILE; | |
76d8aeab DH |
756 | if (max > 65535) |
757 | goto error3; | |
a4014d8f | 758 | size = sizeof(*klist) + sizeof(struct key *) * max; |
1da177e4 LT |
759 | if (size > PAGE_SIZE) |
760 | goto error3; | |
761 | ||
762 | ret = -ENOMEM; | |
763 | nklist = kmalloc(size, GFP_KERNEL); | |
764 | if (!nklist) | |
765 | goto error3; | |
766 | nklist->maxkeys = max; | |
767 | nklist->nkeys = 0; | |
768 | ||
769 | if (klist) { | |
770 | nklist->nkeys = klist->nkeys; | |
771 | memcpy(nklist->keys, | |
772 | klist->keys, | |
773 | sizeof(struct key *) * klist->nkeys); | |
774 | } | |
775 | ||
776 | /* add the key into the new space */ | |
777 | atomic_inc(&key->usage); | |
1da177e4 | 778 | nklist->keys[nklist->nkeys++] = key; |
76d8aeab DH |
779 | |
780 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); | |
1da177e4 LT |
781 | |
782 | /* dispose of the old keyring list */ | |
76d8aeab DH |
783 | if (klist) |
784 | call_rcu(&klist->rcu, keyring_link_rcu_disposal); | |
1da177e4 LT |
785 | } |
786 | ||
cab8eb59 DH |
787 | done: |
788 | ret = 0; | |
789 | error2: | |
1da177e4 | 790 | up_write(&keyring_serialise_link_sem); |
cab8eb59 | 791 | error: |
1da177e4 LT |
792 | return ret; |
793 | ||
cab8eb59 | 794 | error3: |
1da177e4 LT |
795 | /* undo the quota changes */ |
796 | key_payload_reserve(keyring, | |
797 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
798 | goto error2; | |
799 | ||
800 | } /* end __key_link() */ | |
801 | ||
802 | /*****************************************************************************/ | |
803 | /* | |
804 | * link a key to a keyring | |
805 | */ | |
806 | int key_link(struct key *keyring, struct key *key) | |
807 | { | |
808 | int ret; | |
809 | ||
810 | key_check(keyring); | |
811 | key_check(key); | |
812 | ||
813 | down_write(&keyring->sem); | |
814 | ret = __key_link(keyring, key); | |
815 | up_write(&keyring->sem); | |
816 | ||
817 | return ret; | |
818 | ||
819 | } /* end key_link() */ | |
820 | ||
821 | EXPORT_SYMBOL(key_link); | |
822 | ||
823 | /*****************************************************************************/ | |
824 | /* | |
825 | * unlink the first link to a key from a keyring | |
826 | */ | |
827 | int key_unlink(struct key *keyring, struct key *key) | |
828 | { | |
76d8aeab | 829 | struct keyring_list *klist, *nklist; |
1da177e4 LT |
830 | int loop, ret; |
831 | ||
832 | key_check(keyring); | |
833 | key_check(key); | |
834 | ||
835 | ret = -ENOTDIR; | |
836 | if (keyring->type != &key_type_keyring) | |
837 | goto error; | |
838 | ||
839 | down_write(&keyring->sem); | |
840 | ||
841 | klist = keyring->payload.subscriptions; | |
842 | if (klist) { | |
843 | /* search the keyring for the key */ | |
844 | for (loop = 0; loop < klist->nkeys; loop++) | |
845 | if (klist->keys[loop] == key) | |
846 | goto key_is_present; | |
847 | } | |
848 | ||
849 | up_write(&keyring->sem); | |
850 | ret = -ENOENT; | |
851 | goto error; | |
852 | ||
76d8aeab DH |
853 | key_is_present: |
854 | /* we need to copy the key list for RCU purposes */ | |
a4014d8f DH |
855 | nklist = kmalloc(sizeof(*klist) + |
856 | sizeof(struct key *) * klist->maxkeys, | |
76d8aeab DH |
857 | GFP_KERNEL); |
858 | if (!nklist) | |
859 | goto nomem; | |
860 | nklist->maxkeys = klist->maxkeys; | |
861 | nklist->nkeys = klist->nkeys - 1; | |
862 | ||
863 | if (loop > 0) | |
864 | memcpy(&nklist->keys[0], | |
865 | &klist->keys[0], | |
a4014d8f | 866 | loop * sizeof(struct key *)); |
76d8aeab DH |
867 | |
868 | if (loop < nklist->nkeys) | |
869 | memcpy(&nklist->keys[loop], | |
870 | &klist->keys[loop + 1], | |
a4014d8f | 871 | (nklist->nkeys - loop) * sizeof(struct key *)); |
76d8aeab | 872 | |
1da177e4 LT |
873 | /* adjust the user's quota */ |
874 | key_payload_reserve(keyring, | |
875 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
876 | ||
76d8aeab | 877 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
1da177e4 | 878 | |
76d8aeab | 879 | up_write(&keyring->sem); |
1da177e4 | 880 | |
76d8aeab DH |
881 | /* schedule for later cleanup */ |
882 | klist->delkey = loop; | |
883 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
1da177e4 | 884 | |
1da177e4 LT |
885 | ret = 0; |
886 | ||
76d8aeab | 887 | error: |
1da177e4 | 888 | return ret; |
76d8aeab DH |
889 | nomem: |
890 | ret = -ENOMEM; | |
891 | up_write(&keyring->sem); | |
892 | goto error; | |
1da177e4 LT |
893 | |
894 | } /* end key_unlink() */ | |
895 | ||
896 | EXPORT_SYMBOL(key_unlink); | |
897 | ||
76d8aeab DH |
898 | /*****************************************************************************/ |
899 | /* | |
900 | * dispose of a keyring list after the RCU grace period, releasing the keys it | |
901 | * links to | |
902 | */ | |
903 | static void keyring_clear_rcu_disposal(struct rcu_head *rcu) | |
904 | { | |
905 | struct keyring_list *klist; | |
906 | int loop; | |
907 | ||
908 | klist = container_of(rcu, struct keyring_list, rcu); | |
909 | ||
910 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
911 | key_put(klist->keys[loop]); | |
912 | ||
913 | kfree(klist); | |
914 | ||
915 | } /* end keyring_clear_rcu_disposal() */ | |
916 | ||
1da177e4 LT |
917 | /*****************************************************************************/ |
918 | /* | |
919 | * clear the specified process keyring | |
920 | * - implements keyctl(KEYCTL_CLEAR) | |
921 | */ | |
922 | int keyring_clear(struct key *keyring) | |
923 | { | |
924 | struct keyring_list *klist; | |
76d8aeab | 925 | int ret; |
1da177e4 LT |
926 | |
927 | ret = -ENOTDIR; | |
928 | if (keyring->type == &key_type_keyring) { | |
929 | /* detach the pointer block with the locks held */ | |
930 | down_write(&keyring->sem); | |
931 | ||
932 | klist = keyring->payload.subscriptions; | |
933 | if (klist) { | |
934 | /* adjust the quota */ | |
935 | key_payload_reserve(keyring, | |
936 | sizeof(struct keyring_list)); | |
937 | ||
76d8aeab DH |
938 | rcu_assign_pointer(keyring->payload.subscriptions, |
939 | NULL); | |
1da177e4 LT |
940 | } |
941 | ||
942 | up_write(&keyring->sem); | |
943 | ||
944 | /* free the keys after the locks have been dropped */ | |
76d8aeab DH |
945 | if (klist) |
946 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1da177e4 LT |
947 | |
948 | ret = 0; | |
949 | } | |
950 | ||
951 | return ret; | |
952 | ||
953 | } /* end keyring_clear() */ | |
954 | ||
955 | EXPORT_SYMBOL(keyring_clear); |