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 | 51 | static int keyring_match(const struct key *keyring, const void *criterion); |
31204ed9 | 52 | static void keyring_revoke(struct key *keyring); |
1da177e4 LT |
53 | static void keyring_destroy(struct key *keyring); |
54 | static void keyring_describe(const struct key *keyring, struct seq_file *m); | |
55 | static long keyring_read(const struct key *keyring, | |
56 | char __user *buffer, size_t buflen); | |
57 | ||
58 | struct key_type key_type_keyring = { | |
59 | .name = "keyring", | |
60 | .def_datalen = sizeof(struct keyring_list), | |
61 | .instantiate = keyring_instantiate, | |
1da177e4 | 62 | .match = keyring_match, |
31204ed9 | 63 | .revoke = keyring_revoke, |
1da177e4 LT |
64 | .destroy = keyring_destroy, |
65 | .describe = keyring_describe, | |
66 | .read = keyring_read, | |
67 | }; | |
68 | ||
69 | /* | |
70 | * semaphore to serialise link/link calls to prevent two link calls in parallel | |
71 | * introducing a cycle | |
72 | */ | |
1ae8f407 | 73 | static DECLARE_RWSEM(keyring_serialise_link_sem); |
1da177e4 LT |
74 | |
75 | /*****************************************************************************/ | |
76 | /* | |
77 | * publish the name of a keyring so that it can be found by name (if it has | |
78 | * one) | |
79 | */ | |
80 | void keyring_publish_name(struct key *keyring) | |
81 | { | |
82 | int bucket; | |
83 | ||
84 | if (keyring->description) { | |
85 | bucket = keyring_hash(keyring->description); | |
86 | ||
87 | write_lock(&keyring_name_lock); | |
88 | ||
89 | if (!keyring_name_hash[bucket].next) | |
90 | INIT_LIST_HEAD(&keyring_name_hash[bucket]); | |
91 | ||
92 | list_add_tail(&keyring->type_data.link, | |
93 | &keyring_name_hash[bucket]); | |
94 | ||
95 | write_unlock(&keyring_name_lock); | |
96 | } | |
97 | ||
98 | } /* end keyring_publish_name() */ | |
99 | ||
100 | /*****************************************************************************/ | |
101 | /* | |
102 | * initialise a keyring | |
103 | * - we object if we were given any data | |
104 | */ | |
105 | static int keyring_instantiate(struct key *keyring, | |
106 | const void *data, size_t datalen) | |
107 | { | |
108 | int ret; | |
109 | ||
110 | ret = -EINVAL; | |
111 | if (datalen == 0) { | |
112 | /* make the keyring available by name if it has one */ | |
113 | keyring_publish_name(keyring); | |
114 | ret = 0; | |
115 | } | |
116 | ||
117 | return ret; | |
118 | ||
119 | } /* end keyring_instantiate() */ | |
120 | ||
1da177e4 LT |
121 | /*****************************************************************************/ |
122 | /* | |
123 | * match keyrings on their name | |
124 | */ | |
125 | static int keyring_match(const struct key *keyring, const void *description) | |
126 | { | |
127 | return keyring->description && | |
128 | strcmp(keyring->description, description) == 0; | |
129 | ||
130 | } /* end keyring_match() */ | |
131 | ||
132 | /*****************************************************************************/ | |
133 | /* | |
134 | * dispose of the data dangling from the corpse of a keyring | |
135 | */ | |
136 | static void keyring_destroy(struct key *keyring) | |
137 | { | |
138 | struct keyring_list *klist; | |
139 | int loop; | |
140 | ||
141 | if (keyring->description) { | |
142 | write_lock(&keyring_name_lock); | |
94efe72f DH |
143 | |
144 | if (keyring->type_data.link.next != NULL && | |
145 | !list_empty(&keyring->type_data.link)) | |
146 | list_del(&keyring->type_data.link); | |
147 | ||
1da177e4 LT |
148 | write_unlock(&keyring_name_lock); |
149 | } | |
150 | ||
76d8aeab | 151 | klist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
152 | if (klist) { |
153 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
154 | key_put(klist->keys[loop]); | |
155 | kfree(klist); | |
156 | } | |
157 | ||
158 | } /* end keyring_destroy() */ | |
159 | ||
160 | /*****************************************************************************/ | |
161 | /* | |
162 | * describe the keyring | |
163 | */ | |
164 | static void keyring_describe(const struct key *keyring, struct seq_file *m) | |
165 | { | |
166 | struct keyring_list *klist; | |
167 | ||
168 | if (keyring->description) { | |
169 | seq_puts(m, keyring->description); | |
170 | } | |
171 | else { | |
172 | seq_puts(m, "[anon]"); | |
173 | } | |
174 | ||
76d8aeab DH |
175 | rcu_read_lock(); |
176 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
177 | if (klist) |
178 | seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys); | |
179 | else | |
180 | seq_puts(m, ": empty"); | |
76d8aeab | 181 | rcu_read_unlock(); |
1da177e4 LT |
182 | |
183 | } /* end keyring_describe() */ | |
184 | ||
185 | /*****************************************************************************/ | |
186 | /* | |
187 | * read a list of key IDs from the keyring's contents | |
76d8aeab | 188 | * - the keyring's semaphore is read-locked |
1da177e4 LT |
189 | */ |
190 | static long keyring_read(const struct key *keyring, | |
191 | char __user *buffer, size_t buflen) | |
192 | { | |
193 | struct keyring_list *klist; | |
194 | struct key *key; | |
195 | size_t qty, tmp; | |
196 | int loop, ret; | |
197 | ||
198 | ret = 0; | |
76d8aeab | 199 | klist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
200 | |
201 | if (klist) { | |
202 | /* calculate how much data we could return */ | |
203 | qty = klist->nkeys * sizeof(key_serial_t); | |
204 | ||
205 | if (buffer && buflen > 0) { | |
206 | if (buflen > qty) | |
207 | buflen = qty; | |
208 | ||
209 | /* copy the IDs of the subscribed keys into the | |
210 | * buffer */ | |
211 | ret = -EFAULT; | |
212 | ||
213 | for (loop = 0; loop < klist->nkeys; loop++) { | |
214 | key = klist->keys[loop]; | |
215 | ||
216 | tmp = sizeof(key_serial_t); | |
217 | if (tmp > buflen) | |
218 | tmp = buflen; | |
219 | ||
220 | if (copy_to_user(buffer, | |
221 | &key->serial, | |
222 | tmp) != 0) | |
223 | goto error; | |
224 | ||
225 | buflen -= tmp; | |
226 | if (buflen == 0) | |
227 | break; | |
228 | buffer += tmp; | |
229 | } | |
230 | } | |
231 | ||
232 | ret = qty; | |
233 | } | |
234 | ||
235 | error: | |
236 | return ret; | |
237 | ||
238 | } /* end keyring_read() */ | |
239 | ||
240 | /*****************************************************************************/ | |
241 | /* | |
242 | * allocate a keyring and link into the destination keyring | |
243 | */ | |
244 | struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, | |
7e047ef5 | 245 | struct task_struct *ctx, unsigned long flags, |
d720024e | 246 | struct key *dest) |
1da177e4 LT |
247 | { |
248 | struct key *keyring; | |
249 | int ret; | |
250 | ||
251 | keyring = key_alloc(&key_type_keyring, description, | |
d720024e | 252 | uid, gid, ctx, |
29db9190 | 253 | (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, |
7e047ef5 | 254 | flags); |
1da177e4 LT |
255 | |
256 | if (!IS_ERR(keyring)) { | |
3e30148c | 257 | ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); |
1da177e4 LT |
258 | if (ret < 0) { |
259 | key_put(keyring); | |
260 | keyring = ERR_PTR(ret); | |
261 | } | |
262 | } | |
263 | ||
264 | return keyring; | |
265 | ||
266 | } /* end keyring_alloc() */ | |
267 | ||
268 | /*****************************************************************************/ | |
269 | /* | |
270 | * search the supplied keyring tree for a key that matches the criterion | |
271 | * - perform a breadth-then-depth search up to the prescribed limit | |
272 | * - we only find keys on which we have search permission | |
273 | * - we use the supplied match function to see if the description (or other | |
274 | * feature of interest) matches | |
3e30148c | 275 | * - we rely on RCU to prevent the keyring lists from disappearing on us |
1da177e4 LT |
276 | * - we return -EAGAIN if we didn't find any matching key |
277 | * - we return -ENOKEY if we only found negative matching keys | |
664cceb0 | 278 | * - we propagate the possession attribute from the keyring ref to the key ref |
1da177e4 | 279 | */ |
664cceb0 DH |
280 | key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
281 | struct task_struct *context, | |
282 | struct key_type *type, | |
283 | const void *description, | |
284 | key_match_func_t match) | |
1da177e4 LT |
285 | { |
286 | struct { | |
76d8aeab | 287 | struct keyring_list *keylist; |
1da177e4 LT |
288 | int kix; |
289 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
290 | ||
291 | struct keyring_list *keylist; | |
292 | struct timespec now; | |
664cceb0 DH |
293 | unsigned long possessed; |
294 | struct key *keyring, *key; | |
295 | key_ref_t key_ref; | |
1da177e4 | 296 | long err; |
76d8aeab | 297 | int sp, kix; |
1da177e4 | 298 | |
664cceb0 DH |
299 | keyring = key_ref_to_ptr(keyring_ref); |
300 | possessed = is_key_possessed(keyring_ref); | |
1da177e4 LT |
301 | key_check(keyring); |
302 | ||
303 | /* top keyring must have search permission to begin the search */ | |
29db9190 DH |
304 | err = key_task_permission(keyring_ref, context, KEY_SEARCH); |
305 | if (err < 0) { | |
306 | key_ref = ERR_PTR(err); | |
1da177e4 | 307 | goto error; |
29db9190 | 308 | } |
1da177e4 | 309 | |
664cceb0 | 310 | key_ref = ERR_PTR(-ENOTDIR); |
1da177e4 LT |
311 | if (keyring->type != &key_type_keyring) |
312 | goto error; | |
313 | ||
664cceb0 DH |
314 | rcu_read_lock(); |
315 | ||
1da177e4 LT |
316 | now = current_kernel_time(); |
317 | err = -EAGAIN; | |
318 | sp = 0; | |
319 | ||
320 | /* start processing a new keyring */ | |
664cceb0 | 321 | descend: |
76d8aeab | 322 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
323 | goto not_this_keyring; |
324 | ||
76d8aeab | 325 | keylist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
326 | if (!keylist) |
327 | goto not_this_keyring; | |
328 | ||
329 | /* iterate through the keys in this keyring first */ | |
330 | for (kix = 0; kix < keylist->nkeys; kix++) { | |
331 | key = keylist->keys[kix]; | |
332 | ||
333 | /* ignore keys not of this type */ | |
334 | if (key->type != type) | |
335 | continue; | |
336 | ||
337 | /* skip revoked keys and expired keys */ | |
76d8aeab | 338 | if (test_bit(KEY_FLAG_REVOKED, &key->flags)) |
1da177e4 LT |
339 | continue; |
340 | ||
341 | if (key->expiry && now.tv_sec >= key->expiry) | |
342 | continue; | |
343 | ||
344 | /* keys that don't match */ | |
345 | if (!match(key, description)) | |
346 | continue; | |
347 | ||
348 | /* key must have search permissions */ | |
29db9190 DH |
349 | if (key_task_permission(make_key_ref(key, possessed), |
350 | context, KEY_SEARCH) < 0) | |
1da177e4 LT |
351 | continue; |
352 | ||
353 | /* we set a different error code if we find a negative key */ | |
76d8aeab | 354 | if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) { |
1da177e4 LT |
355 | err = -ENOKEY; |
356 | continue; | |
357 | } | |
358 | ||
359 | goto found; | |
360 | } | |
361 | ||
362 | /* search through the keyrings nested in this one */ | |
363 | kix = 0; | |
664cceb0 | 364 | ascend: |
76d8aeab | 365 | for (; kix < keylist->nkeys; kix++) { |
1da177e4 LT |
366 | key = keylist->keys[kix]; |
367 | if (key->type != &key_type_keyring) | |
76d8aeab | 368 | continue; |
1da177e4 LT |
369 | |
370 | /* recursively search nested keyrings | |
371 | * - only search keyrings for which we have search permission | |
372 | */ | |
373 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
76d8aeab | 374 | continue; |
1da177e4 | 375 | |
0f6ed7c2 DH |
376 | if (key_task_permission(make_key_ref(key, possessed), |
377 | context, KEY_SEARCH) < 0) | |
76d8aeab | 378 | continue; |
1da177e4 LT |
379 | |
380 | /* stack the current position */ | |
76d8aeab | 381 | stack[sp].keylist = keylist; |
1da177e4 LT |
382 | stack[sp].kix = kix; |
383 | sp++; | |
384 | ||
385 | /* begin again with the new keyring */ | |
386 | keyring = key; | |
387 | goto descend; | |
1da177e4 LT |
388 | } |
389 | ||
390 | /* the keyring we're looking at was disqualified or didn't contain a | |
391 | * matching key */ | |
664cceb0 | 392 | not_this_keyring: |
1da177e4 LT |
393 | if (sp > 0) { |
394 | /* resume the processing of a keyring higher up in the tree */ | |
395 | sp--; | |
76d8aeab | 396 | keylist = stack[sp].keylist; |
1da177e4 LT |
397 | kix = stack[sp].kix + 1; |
398 | goto ascend; | |
399 | } | |
400 | ||
664cceb0 DH |
401 | key_ref = ERR_PTR(err); |
402 | goto error_2; | |
1da177e4 LT |
403 | |
404 | /* we found a viable match */ | |
664cceb0 | 405 | found: |
1da177e4 | 406 | atomic_inc(&key->usage); |
1da177e4 | 407 | key_check(key); |
664cceb0 DH |
408 | key_ref = make_key_ref(key, possessed); |
409 | error_2: | |
76d8aeab | 410 | rcu_read_unlock(); |
664cceb0 DH |
411 | error: |
412 | return key_ref; | |
1da177e4 LT |
413 | |
414 | } /* end keyring_search_aux() */ | |
415 | ||
416 | /*****************************************************************************/ | |
417 | /* | |
418 | * search the supplied keyring tree for a key that matches the criterion | |
419 | * - perform a breadth-then-depth search up to the prescribed limit | |
420 | * - we only find keys on which we have search permission | |
421 | * - we readlock the keyrings as we search down the tree | |
422 | * - we return -EAGAIN if we didn't find any matching key | |
423 | * - we return -ENOKEY if we only found negative matching keys | |
424 | */ | |
664cceb0 DH |
425 | key_ref_t keyring_search(key_ref_t keyring, |
426 | struct key_type *type, | |
427 | const char *description) | |
1da177e4 | 428 | { |
3e30148c DH |
429 | if (!type->match) |
430 | return ERR_PTR(-ENOKEY); | |
431 | ||
432 | return keyring_search_aux(keyring, current, | |
433 | type, description, type->match); | |
1da177e4 LT |
434 | |
435 | } /* end keyring_search() */ | |
436 | ||
437 | EXPORT_SYMBOL(keyring_search); | |
438 | ||
439 | /*****************************************************************************/ | |
440 | /* | |
441 | * search the given keyring only (no recursion) | |
442 | * - keyring must be locked by caller | |
c3a9d654 | 443 | * - caller must guarantee that the keyring is a keyring |
1da177e4 | 444 | */ |
664cceb0 DH |
445 | key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
446 | const struct key_type *ktype, | |
447 | const char *description, | |
448 | key_perm_t perm) | |
1da177e4 LT |
449 | { |
450 | struct keyring_list *klist; | |
664cceb0 DH |
451 | unsigned long possessed; |
452 | struct key *keyring, *key; | |
1da177e4 LT |
453 | int loop; |
454 | ||
664cceb0 DH |
455 | keyring = key_ref_to_ptr(keyring_ref); |
456 | possessed = is_key_possessed(keyring_ref); | |
457 | ||
76d8aeab DH |
458 | rcu_read_lock(); |
459 | ||
460 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
461 | if (klist) { |
462 | for (loop = 0; loop < klist->nkeys; loop++) { | |
463 | key = klist->keys[loop]; | |
464 | ||
465 | if (key->type == ktype && | |
3e30148c DH |
466 | (!key->type->match || |
467 | key->type->match(key, description)) && | |
664cceb0 | 468 | key_permission(make_key_ref(key, possessed), |
db1d1d57 | 469 | perm) == 0 && |
76d8aeab | 470 | !test_bit(KEY_FLAG_REVOKED, &key->flags) |
1da177e4 LT |
471 | ) |
472 | goto found; | |
473 | } | |
474 | } | |
475 | ||
664cceb0 DH |
476 | rcu_read_unlock(); |
477 | return ERR_PTR(-ENOKEY); | |
1da177e4 LT |
478 | |
479 | found: | |
480 | atomic_inc(&key->usage); | |
76d8aeab | 481 | rcu_read_unlock(); |
664cceb0 | 482 | return make_key_ref(key, possessed); |
1da177e4 LT |
483 | |
484 | } /* end __keyring_search_one() */ | |
485 | ||
486 | /*****************************************************************************/ | |
487 | /* | |
488 | * find a keyring with the specified name | |
489 | * - all named keyrings are searched | |
490 | * - only find keyrings with search permission for the process | |
491 | * - only find keyrings with a serial number greater than the one specified | |
492 | */ | |
493 | struct key *find_keyring_by_name(const char *name, key_serial_t bound) | |
494 | { | |
495 | struct key *keyring; | |
496 | int bucket; | |
497 | ||
498 | keyring = ERR_PTR(-EINVAL); | |
499 | if (!name) | |
500 | goto error; | |
501 | ||
502 | bucket = keyring_hash(name); | |
503 | ||
504 | read_lock(&keyring_name_lock); | |
505 | ||
506 | if (keyring_name_hash[bucket].next) { | |
507 | /* search this hash bucket for a keyring with a matching name | |
508 | * that's readable and that hasn't been revoked */ | |
509 | list_for_each_entry(keyring, | |
510 | &keyring_name_hash[bucket], | |
511 | type_data.link | |
512 | ) { | |
76d8aeab | 513 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
514 | continue; |
515 | ||
516 | if (strcmp(keyring->description, name) != 0) | |
517 | continue; | |
518 | ||
0f6ed7c2 DH |
519 | if (key_permission(make_key_ref(keyring, 0), |
520 | KEY_SEARCH) < 0) | |
1da177e4 LT |
521 | continue; |
522 | ||
523 | /* found a potential candidate, but we still need to | |
524 | * check the serial number */ | |
525 | if (keyring->serial <= bound) | |
526 | continue; | |
527 | ||
528 | /* we've got a match */ | |
529 | atomic_inc(&keyring->usage); | |
530 | read_unlock(&keyring_name_lock); | |
531 | goto error; | |
532 | } | |
533 | } | |
534 | ||
535 | read_unlock(&keyring_name_lock); | |
536 | keyring = ERR_PTR(-ENOKEY); | |
537 | ||
538 | error: | |
539 | return keyring; | |
540 | ||
541 | } /* end find_keyring_by_name() */ | |
542 | ||
543 | /*****************************************************************************/ | |
544 | /* | |
545 | * see if a cycle will will be created by inserting acyclic tree B in acyclic | |
546 | * tree A at the topmost level (ie: as a direct child of A) | |
547 | * - since we are adding B to A at the top level, checking for cycles should | |
548 | * just be a matter of seeing if node A is somewhere in tree B | |
549 | */ | |
550 | static int keyring_detect_cycle(struct key *A, struct key *B) | |
551 | { | |
552 | struct { | |
76d8aeab | 553 | struct keyring_list *keylist; |
1da177e4 LT |
554 | int kix; |
555 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
556 | ||
557 | struct keyring_list *keylist; | |
558 | struct key *subtree, *key; | |
559 | int sp, kix, ret; | |
560 | ||
76d8aeab DH |
561 | rcu_read_lock(); |
562 | ||
1da177e4 LT |
563 | ret = -EDEADLK; |
564 | if (A == B) | |
76d8aeab | 565 | goto cycle_detected; |
1da177e4 LT |
566 | |
567 | subtree = B; | |
568 | sp = 0; | |
569 | ||
570 | /* start processing a new keyring */ | |
571 | descend: | |
76d8aeab | 572 | if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
1da177e4 LT |
573 | goto not_this_keyring; |
574 | ||
76d8aeab | 575 | keylist = rcu_dereference(subtree->payload.subscriptions); |
1da177e4 LT |
576 | if (!keylist) |
577 | goto not_this_keyring; | |
578 | kix = 0; | |
579 | ||
580 | ascend: | |
581 | /* iterate through the remaining keys in this keyring */ | |
582 | for (; kix < keylist->nkeys; kix++) { | |
583 | key = keylist->keys[kix]; | |
584 | ||
585 | if (key == A) | |
586 | goto cycle_detected; | |
587 | ||
588 | /* recursively check nested keyrings */ | |
589 | if (key->type == &key_type_keyring) { | |
590 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
591 | goto too_deep; | |
592 | ||
593 | /* stack the current position */ | |
76d8aeab | 594 | stack[sp].keylist = keylist; |
1da177e4 LT |
595 | stack[sp].kix = kix; |
596 | sp++; | |
597 | ||
598 | /* begin again with the new keyring */ | |
599 | subtree = key; | |
600 | goto descend; | |
601 | } | |
602 | } | |
603 | ||
604 | /* the keyring we're looking at was disqualified or didn't contain a | |
605 | * matching key */ | |
606 | not_this_keyring: | |
1da177e4 LT |
607 | if (sp > 0) { |
608 | /* resume the checking of a keyring higher up in the tree */ | |
609 | sp--; | |
76d8aeab | 610 | keylist = stack[sp].keylist; |
1da177e4 LT |
611 | kix = stack[sp].kix + 1; |
612 | goto ascend; | |
613 | } | |
614 | ||
615 | ret = 0; /* no cycles detected */ | |
616 | ||
617 | error: | |
76d8aeab | 618 | rcu_read_unlock(); |
1da177e4 LT |
619 | return ret; |
620 | ||
621 | too_deep: | |
622 | ret = -ELOOP; | |
76d8aeab DH |
623 | goto error; |
624 | ||
1da177e4 LT |
625 | cycle_detected: |
626 | ret = -EDEADLK; | |
1da177e4 LT |
627 | goto error; |
628 | ||
629 | } /* end keyring_detect_cycle() */ | |
630 | ||
76d8aeab DH |
631 | /*****************************************************************************/ |
632 | /* | |
633 | * dispose of a keyring list after the RCU grace period | |
634 | */ | |
635 | static void keyring_link_rcu_disposal(struct rcu_head *rcu) | |
636 | { | |
637 | struct keyring_list *klist = | |
638 | container_of(rcu, struct keyring_list, rcu); | |
639 | ||
640 | kfree(klist); | |
641 | ||
642 | } /* end keyring_link_rcu_disposal() */ | |
643 | ||
cab8eb59 DH |
644 | /*****************************************************************************/ |
645 | /* | |
646 | * dispose of a keyring list after the RCU grace period, freeing the unlinked | |
647 | * key | |
648 | */ | |
649 | static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) | |
650 | { | |
651 | struct keyring_list *klist = | |
652 | container_of(rcu, struct keyring_list, rcu); | |
653 | ||
654 | key_put(klist->keys[klist->delkey]); | |
655 | kfree(klist); | |
656 | ||
657 | } /* end keyring_unlink_rcu_disposal() */ | |
658 | ||
1da177e4 LT |
659 | /*****************************************************************************/ |
660 | /* | |
661 | * link a key into to a keyring | |
76d8aeab | 662 | * - must be called with the keyring's semaphore write-locked |
cab8eb59 | 663 | * - discard already extant link to matching key if there is one |
1da177e4 LT |
664 | */ |
665 | int __key_link(struct key *keyring, struct key *key) | |
666 | { | |
667 | struct keyring_list *klist, *nklist; | |
668 | unsigned max; | |
669 | size_t size; | |
cab8eb59 | 670 | int loop, ret; |
1da177e4 LT |
671 | |
672 | ret = -EKEYREVOKED; | |
76d8aeab | 673 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
674 | goto error; |
675 | ||
676 | ret = -ENOTDIR; | |
677 | if (keyring->type != &key_type_keyring) | |
678 | goto error; | |
679 | ||
680 | /* serialise link/link calls to prevent parallel calls causing a | |
681 | * cycle when applied to two keyring in opposite orders */ | |
682 | down_write(&keyring_serialise_link_sem); | |
683 | ||
684 | /* check that we aren't going to create a cycle adding one keyring to | |
685 | * another */ | |
686 | if (key->type == &key_type_keyring) { | |
687 | ret = keyring_detect_cycle(keyring, key); | |
688 | if (ret < 0) | |
689 | goto error2; | |
690 | } | |
691 | ||
cab8eb59 DH |
692 | /* see if there's a matching key we can displace */ |
693 | klist = keyring->payload.subscriptions; | |
694 | ||
695 | if (klist && klist->nkeys > 0) { | |
696 | struct key_type *type = key->type; | |
697 | ||
698 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { | |
699 | if (klist->keys[loop]->type == type && | |
700 | strcmp(klist->keys[loop]->description, | |
701 | key->description) == 0 | |
702 | ) { | |
703 | /* found a match - replace with new key */ | |
704 | size = sizeof(struct key *) * klist->maxkeys; | |
705 | size += sizeof(*klist); | |
706 | BUG_ON(size > PAGE_SIZE); | |
707 | ||
708 | ret = -ENOMEM; | |
48ad504e | 709 | nklist = kmemdup(klist, size, GFP_KERNEL); |
cab8eb59 DH |
710 | if (!nklist) |
711 | goto error2; | |
712 | ||
cab8eb59 DH |
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); | |
31204ed9 DH |
956 | |
957 | /*****************************************************************************/ | |
958 | /* | |
959 | * dispose of the links from a revoked keyring | |
960 | * - called with the key sem write-locked | |
961 | */ | |
962 | static void keyring_revoke(struct key *keyring) | |
963 | { | |
964 | struct keyring_list *klist = keyring->payload.subscriptions; | |
965 | ||
966 | /* adjust the quota */ | |
967 | key_payload_reserve(keyring, 0); | |
968 | ||
969 | if (klist) { | |
970 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
971 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
972 | } | |
973 | ||
974 | } /* end keyring_revoke() */ |