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Commit | Line | Data |
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69664cf1 | 1 | /* Keyring handling |
1da177e4 | 2 | * |
69664cf1 | 3 | * Copyright (C) 2004-2005, 2008 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> | |
e9e349b0 | 19 | #include <keys/keyring-type.h> |
512ea3bc | 20 | #include <linux/uaccess.h> |
1da177e4 LT |
21 | #include "internal.h" |
22 | ||
f0641cba DH |
23 | #define rcu_dereference_locked_keyring(keyring) \ |
24 | (rcu_dereference_protected( \ | |
25 | (keyring)->payload.subscriptions, \ | |
26 | rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem))) | |
27 | ||
ceb73c12 DH |
28 | #define KEY_LINK_FIXQUOTA 1UL |
29 | ||
1da177e4 | 30 | /* |
973c9f4f DH |
31 | * When plumbing the depths of the key tree, this sets a hard limit |
32 | * set on how deep we're willing to go. | |
1da177e4 LT |
33 | */ |
34 | #define KEYRING_SEARCH_MAX_DEPTH 6 | |
35 | ||
36 | /* | |
973c9f4f | 37 | * We keep all named keyrings in a hash to speed looking them up. |
1da177e4 LT |
38 | */ |
39 | #define KEYRING_NAME_HASH_SIZE (1 << 5) | |
40 | ||
41 | static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE]; | |
42 | static DEFINE_RWLOCK(keyring_name_lock); | |
43 | ||
44 | static inline unsigned keyring_hash(const char *desc) | |
45 | { | |
46 | unsigned bucket = 0; | |
47 | ||
48 | for (; *desc; desc++) | |
c5b60b5e | 49 | bucket += (unsigned char)*desc; |
1da177e4 LT |
50 | |
51 | return bucket & (KEYRING_NAME_HASH_SIZE - 1); | |
52 | } | |
53 | ||
54 | /* | |
973c9f4f DH |
55 | * The keyring key type definition. Keyrings are simply keys of this type and |
56 | * can be treated as ordinary keys in addition to having their own special | |
57 | * operations. | |
1da177e4 LT |
58 | */ |
59 | static int keyring_instantiate(struct key *keyring, | |
60 | const void *data, size_t datalen); | |
1da177e4 | 61 | static int keyring_match(const struct key *keyring, const void *criterion); |
31204ed9 | 62 | static void keyring_revoke(struct key *keyring); |
1da177e4 LT |
63 | static void keyring_destroy(struct key *keyring); |
64 | static void keyring_describe(const struct key *keyring, struct seq_file *m); | |
65 | static long keyring_read(const struct key *keyring, | |
66 | char __user *buffer, size_t buflen); | |
67 | ||
68 | struct key_type key_type_keyring = { | |
69 | .name = "keyring", | |
70 | .def_datalen = sizeof(struct keyring_list), | |
71 | .instantiate = keyring_instantiate, | |
1da177e4 | 72 | .match = keyring_match, |
31204ed9 | 73 | .revoke = keyring_revoke, |
1da177e4 LT |
74 | .destroy = keyring_destroy, |
75 | .describe = keyring_describe, | |
76 | .read = keyring_read, | |
77 | }; | |
7318226e DH |
78 | EXPORT_SYMBOL(key_type_keyring); |
79 | ||
1da177e4 | 80 | /* |
973c9f4f DH |
81 | * Semaphore to serialise link/link calls to prevent two link calls in parallel |
82 | * introducing a cycle. | |
1da177e4 | 83 | */ |
1ae8f407 | 84 | static DECLARE_RWSEM(keyring_serialise_link_sem); |
1da177e4 | 85 | |
1da177e4 | 86 | /* |
973c9f4f DH |
87 | * Publish the name of a keyring so that it can be found by name (if it has |
88 | * one). | |
1da177e4 | 89 | */ |
69664cf1 | 90 | static void keyring_publish_name(struct key *keyring) |
1da177e4 LT |
91 | { |
92 | int bucket; | |
93 | ||
94 | if (keyring->description) { | |
95 | bucket = keyring_hash(keyring->description); | |
96 | ||
97 | write_lock(&keyring_name_lock); | |
98 | ||
99 | if (!keyring_name_hash[bucket].next) | |
100 | INIT_LIST_HEAD(&keyring_name_hash[bucket]); | |
101 | ||
102 | list_add_tail(&keyring->type_data.link, | |
103 | &keyring_name_hash[bucket]); | |
104 | ||
105 | write_unlock(&keyring_name_lock); | |
106 | } | |
a8b17ed0 | 107 | } |
1da177e4 | 108 | |
1da177e4 | 109 | /* |
973c9f4f DH |
110 | * Initialise a keyring. |
111 | * | |
112 | * Returns 0 on success, -EINVAL if given any data. | |
1da177e4 LT |
113 | */ |
114 | static int keyring_instantiate(struct key *keyring, | |
115 | const void *data, size_t datalen) | |
116 | { | |
117 | int ret; | |
118 | ||
119 | ret = -EINVAL; | |
120 | if (datalen == 0) { | |
121 | /* make the keyring available by name if it has one */ | |
122 | keyring_publish_name(keyring); | |
123 | ret = 0; | |
124 | } | |
125 | ||
126 | return ret; | |
a8b17ed0 | 127 | } |
1da177e4 | 128 | |
1da177e4 | 129 | /* |
973c9f4f | 130 | * Match keyrings on their name |
1da177e4 LT |
131 | */ |
132 | static int keyring_match(const struct key *keyring, const void *description) | |
133 | { | |
134 | return keyring->description && | |
135 | strcmp(keyring->description, description) == 0; | |
a8b17ed0 | 136 | } |
1da177e4 | 137 | |
1da177e4 | 138 | /* |
973c9f4f DH |
139 | * Clean up a keyring when it is destroyed. Unpublish its name if it had one |
140 | * and dispose of its data. | |
1da177e4 LT |
141 | */ |
142 | static void keyring_destroy(struct key *keyring) | |
143 | { | |
144 | struct keyring_list *klist; | |
145 | int loop; | |
146 | ||
147 | if (keyring->description) { | |
148 | write_lock(&keyring_name_lock); | |
94efe72f DH |
149 | |
150 | if (keyring->type_data.link.next != NULL && | |
151 | !list_empty(&keyring->type_data.link)) | |
152 | list_del(&keyring->type_data.link); | |
153 | ||
1da177e4 LT |
154 | write_unlock(&keyring_name_lock); |
155 | } | |
156 | ||
e7b0a61b PM |
157 | klist = rcu_dereference_check(keyring->payload.subscriptions, |
158 | rcu_read_lock_held() || | |
159 | atomic_read(&keyring->usage) == 0); | |
1da177e4 LT |
160 | if (klist) { |
161 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
162 | key_put(klist->keys[loop]); | |
163 | kfree(klist); | |
164 | } | |
a8b17ed0 | 165 | } |
1da177e4 | 166 | |
1da177e4 | 167 | /* |
973c9f4f | 168 | * Describe a keyring for /proc. |
1da177e4 LT |
169 | */ |
170 | static void keyring_describe(const struct key *keyring, struct seq_file *m) | |
171 | { | |
172 | struct keyring_list *klist; | |
173 | ||
c8563473 | 174 | if (keyring->description) |
1da177e4 | 175 | seq_puts(m, keyring->description); |
c8563473 | 176 | else |
1da177e4 | 177 | seq_puts(m, "[anon]"); |
1da177e4 | 178 | |
76d8aeab DH |
179 | rcu_read_lock(); |
180 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
181 | if (klist) |
182 | seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys); | |
183 | else | |
184 | seq_puts(m, ": empty"); | |
76d8aeab | 185 | rcu_read_unlock(); |
a8b17ed0 | 186 | } |
1da177e4 | 187 | |
1da177e4 | 188 | /* |
973c9f4f DH |
189 | * Read a list of key IDs from the keyring's contents in binary form |
190 | * | |
191 | * The keyring's semaphore is read-locked by the caller. | |
1da177e4 LT |
192 | */ |
193 | static long keyring_read(const struct key *keyring, | |
194 | char __user *buffer, size_t buflen) | |
195 | { | |
196 | struct keyring_list *klist; | |
197 | struct key *key; | |
198 | size_t qty, tmp; | |
199 | int loop, ret; | |
200 | ||
201 | ret = 0; | |
f0641cba | 202 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
203 | if (klist) { |
204 | /* calculate how much data we could return */ | |
205 | qty = klist->nkeys * sizeof(key_serial_t); | |
206 | ||
207 | if (buffer && buflen > 0) { | |
208 | if (buflen > qty) | |
209 | buflen = qty; | |
210 | ||
211 | /* copy the IDs of the subscribed keys into the | |
212 | * buffer */ | |
213 | ret = -EFAULT; | |
214 | ||
215 | for (loop = 0; loop < klist->nkeys; loop++) { | |
216 | key = klist->keys[loop]; | |
217 | ||
218 | tmp = sizeof(key_serial_t); | |
219 | if (tmp > buflen) | |
220 | tmp = buflen; | |
221 | ||
222 | if (copy_to_user(buffer, | |
223 | &key->serial, | |
224 | tmp) != 0) | |
225 | goto error; | |
226 | ||
227 | buflen -= tmp; | |
228 | if (buflen == 0) | |
229 | break; | |
230 | buffer += tmp; | |
231 | } | |
232 | } | |
233 | ||
234 | ret = qty; | |
235 | } | |
236 | ||
c5b60b5e | 237 | error: |
1da177e4 | 238 | return ret; |
a8b17ed0 | 239 | } |
1da177e4 | 240 | |
1da177e4 | 241 | /* |
973c9f4f | 242 | * Allocate a keyring and link into the destination keyring. |
1da177e4 LT |
243 | */ |
244 | struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, | |
d84f4f99 | 245 | const struct cred *cred, 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, | |
d84f4f99 | 252 | uid, gid, cred, |
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; | |
a8b17ed0 | 265 | } |
1da177e4 | 266 | |
973c9f4f DH |
267 | /** |
268 | * keyring_search_aux - Search a keyring tree for a key matching some criteria | |
269 | * @keyring_ref: A pointer to the keyring with possession indicator. | |
270 | * @cred: The credentials to use for permissions checks. | |
271 | * @type: The type of key to search for. | |
272 | * @description: Parameter for @match. | |
273 | * @match: Function to rule on whether or not a key is the one required. | |
274 | * | |
275 | * Search the supplied keyring tree for a key that matches the criteria given. | |
276 | * The root keyring and any linked keyrings must grant Search permission to the | |
277 | * caller to be searchable and keys can only be found if they too grant Search | |
278 | * to the caller. The possession flag on the root keyring pointer controls use | |
279 | * of the possessor bits in permissions checking of the entire tree. In | |
280 | * addition, the LSM gets to forbid keyring searches and key matches. | |
281 | * | |
282 | * The search is performed as a breadth-then-depth search up to the prescribed | |
283 | * limit (KEYRING_SEARCH_MAX_DEPTH). | |
284 | * | |
285 | * Keys are matched to the type provided and are then filtered by the match | |
286 | * function, which is given the description to use in any way it sees fit. The | |
287 | * match function may use any attributes of a key that it wishes to to | |
288 | * determine the match. Normally the match function from the key type would be | |
289 | * used. | |
290 | * | |
291 | * RCU is used to prevent the keyring key lists from disappearing without the | |
292 | * need to take lots of locks. | |
293 | * | |
294 | * Returns a pointer to the found key and increments the key usage count if | |
295 | * successful; -EAGAIN if no matching keys were found, or if expired or revoked | |
296 | * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the | |
297 | * specified keyring wasn't a keyring. | |
298 | * | |
299 | * In the case of a successful return, the possession attribute from | |
300 | * @keyring_ref is propagated to the returned key reference. | |
1da177e4 | 301 | */ |
664cceb0 | 302 | key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
d84f4f99 | 303 | const struct cred *cred, |
664cceb0 DH |
304 | struct key_type *type, |
305 | const void *description, | |
306 | key_match_func_t match) | |
1da177e4 LT |
307 | { |
308 | struct { | |
76d8aeab | 309 | struct keyring_list *keylist; |
1da177e4 LT |
310 | int kix; |
311 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
312 | ||
313 | struct keyring_list *keylist; | |
314 | struct timespec now; | |
dceba994 | 315 | unsigned long possessed, kflags; |
664cceb0 DH |
316 | struct key *keyring, *key; |
317 | key_ref_t key_ref; | |
1da177e4 | 318 | long err; |
76d8aeab | 319 | int sp, kix; |
1da177e4 | 320 | |
664cceb0 DH |
321 | keyring = key_ref_to_ptr(keyring_ref); |
322 | possessed = is_key_possessed(keyring_ref); | |
1da177e4 LT |
323 | key_check(keyring); |
324 | ||
325 | /* top keyring must have search permission to begin the search */ | |
512ea3bc | 326 | err = key_task_permission(keyring_ref, cred, KEY_SEARCH); |
29db9190 DH |
327 | if (err < 0) { |
328 | key_ref = ERR_PTR(err); | |
1da177e4 | 329 | goto error; |
29db9190 | 330 | } |
1da177e4 | 331 | |
664cceb0 | 332 | key_ref = ERR_PTR(-ENOTDIR); |
1da177e4 LT |
333 | if (keyring->type != &key_type_keyring) |
334 | goto error; | |
335 | ||
664cceb0 DH |
336 | rcu_read_lock(); |
337 | ||
1da177e4 LT |
338 | now = current_kernel_time(); |
339 | err = -EAGAIN; | |
340 | sp = 0; | |
341 | ||
dceba994 KC |
342 | /* firstly we should check to see if this top-level keyring is what we |
343 | * are looking for */ | |
344 | key_ref = ERR_PTR(-EAGAIN); | |
345 | kflags = keyring->flags; | |
346 | if (keyring->type == type && match(keyring, description)) { | |
347 | key = keyring; | |
348 | ||
349 | /* check it isn't negative and hasn't expired or been | |
350 | * revoked */ | |
351 | if (kflags & (1 << KEY_FLAG_REVOKED)) | |
352 | goto error_2; | |
353 | if (key->expiry && now.tv_sec >= key->expiry) | |
354 | goto error_2; | |
fdd1b945 | 355 | key_ref = ERR_PTR(key->type_data.reject_error); |
dceba994 KC |
356 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) |
357 | goto error_2; | |
358 | goto found; | |
359 | } | |
360 | ||
361 | /* otherwise, the top keyring must not be revoked, expired, or | |
362 | * negatively instantiated if we are to search it */ | |
363 | key_ref = ERR_PTR(-EAGAIN); | |
364 | if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) || | |
365 | (keyring->expiry && now.tv_sec >= keyring->expiry)) | |
366 | goto error_2; | |
367 | ||
1da177e4 | 368 | /* start processing a new keyring */ |
664cceb0 | 369 | descend: |
76d8aeab | 370 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
371 | goto not_this_keyring; |
372 | ||
76d8aeab | 373 | keylist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
374 | if (!keylist) |
375 | goto not_this_keyring; | |
376 | ||
377 | /* iterate through the keys in this keyring first */ | |
378 | for (kix = 0; kix < keylist->nkeys; kix++) { | |
379 | key = keylist->keys[kix]; | |
dceba994 | 380 | kflags = key->flags; |
1da177e4 LT |
381 | |
382 | /* ignore keys not of this type */ | |
383 | if (key->type != type) | |
384 | continue; | |
385 | ||
386 | /* skip revoked keys and expired keys */ | |
dceba994 | 387 | if (kflags & (1 << KEY_FLAG_REVOKED)) |
1da177e4 LT |
388 | continue; |
389 | ||
390 | if (key->expiry && now.tv_sec >= key->expiry) | |
391 | continue; | |
392 | ||
393 | /* keys that don't match */ | |
394 | if (!match(key, description)) | |
395 | continue; | |
396 | ||
397 | /* key must have search permissions */ | |
29db9190 | 398 | if (key_task_permission(make_key_ref(key, possessed), |
d84f4f99 | 399 | cred, KEY_SEARCH) < 0) |
1da177e4 LT |
400 | continue; |
401 | ||
dceba994 KC |
402 | /* we set a different error code if we pass a negative key */ |
403 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) { | |
fdd1b945 | 404 | err = key->type_data.reject_error; |
1da177e4 LT |
405 | continue; |
406 | } | |
407 | ||
408 | goto found; | |
409 | } | |
410 | ||
411 | /* search through the keyrings nested in this one */ | |
412 | kix = 0; | |
664cceb0 | 413 | ascend: |
76d8aeab | 414 | for (; kix < keylist->nkeys; kix++) { |
1da177e4 LT |
415 | key = keylist->keys[kix]; |
416 | if (key->type != &key_type_keyring) | |
76d8aeab | 417 | continue; |
1da177e4 LT |
418 | |
419 | /* recursively search nested keyrings | |
420 | * - only search keyrings for which we have search permission | |
421 | */ | |
422 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
76d8aeab | 423 | continue; |
1da177e4 | 424 | |
0f6ed7c2 | 425 | if (key_task_permission(make_key_ref(key, possessed), |
d84f4f99 | 426 | cred, KEY_SEARCH) < 0) |
76d8aeab | 427 | continue; |
1da177e4 LT |
428 | |
429 | /* stack the current position */ | |
76d8aeab | 430 | stack[sp].keylist = keylist; |
1da177e4 LT |
431 | stack[sp].kix = kix; |
432 | sp++; | |
433 | ||
434 | /* begin again with the new keyring */ | |
435 | keyring = key; | |
436 | goto descend; | |
1da177e4 LT |
437 | } |
438 | ||
439 | /* the keyring we're looking at was disqualified or didn't contain a | |
440 | * matching key */ | |
664cceb0 | 441 | not_this_keyring: |
1da177e4 LT |
442 | if (sp > 0) { |
443 | /* resume the processing of a keyring higher up in the tree */ | |
444 | sp--; | |
76d8aeab | 445 | keylist = stack[sp].keylist; |
1da177e4 LT |
446 | kix = stack[sp].kix + 1; |
447 | goto ascend; | |
448 | } | |
449 | ||
664cceb0 DH |
450 | key_ref = ERR_PTR(err); |
451 | goto error_2; | |
1da177e4 LT |
452 | |
453 | /* we found a viable match */ | |
664cceb0 | 454 | found: |
1da177e4 | 455 | atomic_inc(&key->usage); |
1da177e4 | 456 | key_check(key); |
664cceb0 DH |
457 | key_ref = make_key_ref(key, possessed); |
458 | error_2: | |
76d8aeab | 459 | rcu_read_unlock(); |
664cceb0 DH |
460 | error: |
461 | return key_ref; | |
a8b17ed0 | 462 | } |
1da177e4 | 463 | |
973c9f4f DH |
464 | /** |
465 | * keyring_search - Search the supplied keyring tree for a matching key | |
466 | * @keyring: The root of the keyring tree to be searched. | |
467 | * @type: The type of keyring we want to find. | |
468 | * @description: The name of the keyring we want to find. | |
469 | * | |
470 | * As keyring_search_aux() above, but using the current task's credentials and | |
471 | * type's default matching function. | |
1da177e4 | 472 | */ |
664cceb0 DH |
473 | key_ref_t keyring_search(key_ref_t keyring, |
474 | struct key_type *type, | |
475 | const char *description) | |
1da177e4 | 476 | { |
3e30148c DH |
477 | if (!type->match) |
478 | return ERR_PTR(-ENOKEY); | |
479 | ||
d84f4f99 | 480 | return keyring_search_aux(keyring, current->cred, |
3e30148c | 481 | type, description, type->match); |
a8b17ed0 | 482 | } |
1da177e4 LT |
483 | EXPORT_SYMBOL(keyring_search); |
484 | ||
1da177e4 | 485 | /* |
973c9f4f DH |
486 | * Search the given keyring only (no recursion). |
487 | * | |
488 | * The caller must guarantee that the keyring is a keyring and that the | |
489 | * permission is granted to search the keyring as no check is made here. | |
490 | * | |
491 | * RCU is used to make it unnecessary to lock the keyring key list here. | |
492 | * | |
493 | * Returns a pointer to the found key with usage count incremented if | |
494 | * successful and returns -ENOKEY if not found. Revoked keys and keys not | |
495 | * providing the requested permission are skipped over. | |
496 | * | |
497 | * If successful, the possession indicator is propagated from the keyring ref | |
498 | * to the returned key reference. | |
1da177e4 | 499 | */ |
664cceb0 DH |
500 | key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
501 | const struct key_type *ktype, | |
502 | const char *description, | |
503 | key_perm_t perm) | |
1da177e4 LT |
504 | { |
505 | struct keyring_list *klist; | |
664cceb0 DH |
506 | unsigned long possessed; |
507 | struct key *keyring, *key; | |
1da177e4 LT |
508 | int loop; |
509 | ||
664cceb0 DH |
510 | keyring = key_ref_to_ptr(keyring_ref); |
511 | possessed = is_key_possessed(keyring_ref); | |
512 | ||
76d8aeab DH |
513 | rcu_read_lock(); |
514 | ||
515 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
516 | if (klist) { |
517 | for (loop = 0; loop < klist->nkeys; loop++) { | |
518 | key = klist->keys[loop]; | |
519 | ||
520 | if (key->type == ktype && | |
3e30148c DH |
521 | (!key->type->match || |
522 | key->type->match(key, description)) && | |
664cceb0 | 523 | key_permission(make_key_ref(key, possessed), |
db1d1d57 | 524 | perm) == 0 && |
76d8aeab | 525 | !test_bit(KEY_FLAG_REVOKED, &key->flags) |
1da177e4 LT |
526 | ) |
527 | goto found; | |
528 | } | |
529 | } | |
530 | ||
664cceb0 DH |
531 | rcu_read_unlock(); |
532 | return ERR_PTR(-ENOKEY); | |
1da177e4 | 533 | |
c5b60b5e | 534 | found: |
1da177e4 | 535 | atomic_inc(&key->usage); |
76d8aeab | 536 | rcu_read_unlock(); |
664cceb0 | 537 | return make_key_ref(key, possessed); |
a8b17ed0 | 538 | } |
1da177e4 | 539 | |
1da177e4 | 540 | /* |
973c9f4f DH |
541 | * Find a keyring with the specified name. |
542 | * | |
543 | * All named keyrings in the current user namespace are searched, provided they | |
544 | * grant Search permission directly to the caller (unless this check is | |
545 | * skipped). Keyrings whose usage points have reached zero or who have been | |
546 | * revoked are skipped. | |
547 | * | |
548 | * Returns a pointer to the keyring with the keyring's refcount having being | |
549 | * incremented on success. -ENOKEY is returned if a key could not be found. | |
1da177e4 | 550 | */ |
69664cf1 | 551 | struct key *find_keyring_by_name(const char *name, bool skip_perm_check) |
1da177e4 LT |
552 | { |
553 | struct key *keyring; | |
554 | int bucket; | |
555 | ||
1da177e4 | 556 | if (!name) |
cea7daa3 | 557 | return ERR_PTR(-EINVAL); |
1da177e4 LT |
558 | |
559 | bucket = keyring_hash(name); | |
560 | ||
561 | read_lock(&keyring_name_lock); | |
562 | ||
563 | if (keyring_name_hash[bucket].next) { | |
564 | /* search this hash bucket for a keyring with a matching name | |
565 | * that's readable and that hasn't been revoked */ | |
566 | list_for_each_entry(keyring, | |
567 | &keyring_name_hash[bucket], | |
568 | type_data.link | |
569 | ) { | |
2ea190d0 SH |
570 | if (keyring->user->user_ns != current_user_ns()) |
571 | continue; | |
572 | ||
76d8aeab | 573 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
574 | continue; |
575 | ||
576 | if (strcmp(keyring->description, name) != 0) | |
577 | continue; | |
578 | ||
69664cf1 DH |
579 | if (!skip_perm_check && |
580 | key_permission(make_key_ref(keyring, 0), | |
0f6ed7c2 | 581 | KEY_SEARCH) < 0) |
1da177e4 LT |
582 | continue; |
583 | ||
cea7daa3 TO |
584 | /* we've got a match but we might end up racing with |
585 | * key_cleanup() if the keyring is currently 'dead' | |
586 | * (ie. it has a zero usage count) */ | |
587 | if (!atomic_inc_not_zero(&keyring->usage)) | |
588 | continue; | |
589 | goto out; | |
1da177e4 LT |
590 | } |
591 | } | |
592 | ||
1da177e4 | 593 | keyring = ERR_PTR(-ENOKEY); |
cea7daa3 TO |
594 | out: |
595 | read_unlock(&keyring_name_lock); | |
1da177e4 | 596 | return keyring; |
a8b17ed0 | 597 | } |
1da177e4 | 598 | |
1da177e4 | 599 | /* |
973c9f4f DH |
600 | * See if a cycle will will be created by inserting acyclic tree B in acyclic |
601 | * tree A at the topmost level (ie: as a direct child of A). | |
602 | * | |
603 | * Since we are adding B to A at the top level, checking for cycles should just | |
604 | * be a matter of seeing if node A is somewhere in tree B. | |
1da177e4 LT |
605 | */ |
606 | static int keyring_detect_cycle(struct key *A, struct key *B) | |
607 | { | |
608 | struct { | |
76d8aeab | 609 | struct keyring_list *keylist; |
1da177e4 LT |
610 | int kix; |
611 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
612 | ||
613 | struct keyring_list *keylist; | |
614 | struct key *subtree, *key; | |
615 | int sp, kix, ret; | |
616 | ||
76d8aeab DH |
617 | rcu_read_lock(); |
618 | ||
1da177e4 LT |
619 | ret = -EDEADLK; |
620 | if (A == B) | |
76d8aeab | 621 | goto cycle_detected; |
1da177e4 LT |
622 | |
623 | subtree = B; | |
624 | sp = 0; | |
625 | ||
626 | /* start processing a new keyring */ | |
c5b60b5e | 627 | descend: |
76d8aeab | 628 | if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
1da177e4 LT |
629 | goto not_this_keyring; |
630 | ||
76d8aeab | 631 | keylist = rcu_dereference(subtree->payload.subscriptions); |
1da177e4 LT |
632 | if (!keylist) |
633 | goto not_this_keyring; | |
634 | kix = 0; | |
635 | ||
c5b60b5e | 636 | ascend: |
1da177e4 LT |
637 | /* iterate through the remaining keys in this keyring */ |
638 | for (; kix < keylist->nkeys; kix++) { | |
639 | key = keylist->keys[kix]; | |
640 | ||
641 | if (key == A) | |
642 | goto cycle_detected; | |
643 | ||
644 | /* recursively check nested keyrings */ | |
645 | if (key->type == &key_type_keyring) { | |
646 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
647 | goto too_deep; | |
648 | ||
649 | /* stack the current position */ | |
76d8aeab | 650 | stack[sp].keylist = keylist; |
1da177e4 LT |
651 | stack[sp].kix = kix; |
652 | sp++; | |
653 | ||
654 | /* begin again with the new keyring */ | |
655 | subtree = key; | |
656 | goto descend; | |
657 | } | |
658 | } | |
659 | ||
660 | /* the keyring we're looking at was disqualified or didn't contain a | |
661 | * matching key */ | |
c5b60b5e | 662 | not_this_keyring: |
1da177e4 LT |
663 | if (sp > 0) { |
664 | /* resume the checking of a keyring higher up in the tree */ | |
665 | sp--; | |
76d8aeab | 666 | keylist = stack[sp].keylist; |
1da177e4 LT |
667 | kix = stack[sp].kix + 1; |
668 | goto ascend; | |
669 | } | |
670 | ||
671 | ret = 0; /* no cycles detected */ | |
672 | ||
c5b60b5e | 673 | error: |
76d8aeab | 674 | rcu_read_unlock(); |
1da177e4 LT |
675 | return ret; |
676 | ||
c5b60b5e | 677 | too_deep: |
1da177e4 | 678 | ret = -ELOOP; |
76d8aeab DH |
679 | goto error; |
680 | ||
c5b60b5e | 681 | cycle_detected: |
1da177e4 | 682 | ret = -EDEADLK; |
1da177e4 | 683 | goto error; |
a8b17ed0 | 684 | } |
1da177e4 | 685 | |
cab8eb59 | 686 | /* |
973c9f4f | 687 | * Dispose of a keyring list after the RCU grace period, freeing the unlinked |
cab8eb59 DH |
688 | * key |
689 | */ | |
690 | static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) | |
691 | { | |
692 | struct keyring_list *klist = | |
693 | container_of(rcu, struct keyring_list, rcu); | |
694 | ||
4be929be | 695 | if (klist->delkey != USHRT_MAX) |
f70e2e06 | 696 | key_put(klist->keys[klist->delkey]); |
cab8eb59 | 697 | kfree(klist); |
f70e2e06 | 698 | } |
cab8eb59 | 699 | |
1da177e4 | 700 | /* |
973c9f4f | 701 | * Preallocate memory so that a key can be linked into to a keyring. |
1da177e4 | 702 | */ |
f70e2e06 | 703 | int __key_link_begin(struct key *keyring, const struct key_type *type, |
ceb73c12 | 704 | const char *description, unsigned long *_prealloc) |
f70e2e06 | 705 | __acquires(&keyring->sem) |
1da177e4 LT |
706 | { |
707 | struct keyring_list *klist, *nklist; | |
ceb73c12 | 708 | unsigned long prealloc; |
1da177e4 LT |
709 | unsigned max; |
710 | size_t size; | |
cab8eb59 | 711 | int loop, ret; |
1da177e4 | 712 | |
f70e2e06 | 713 | kenter("%d,%s,%s,", key_serial(keyring), type->name, description); |
1da177e4 | 714 | |
1da177e4 | 715 | if (keyring->type != &key_type_keyring) |
f70e2e06 DH |
716 | return -ENOTDIR; |
717 | ||
718 | down_write(&keyring->sem); | |
719 | ||
720 | ret = -EKEYREVOKED; | |
721 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) | |
722 | goto error_krsem; | |
1da177e4 | 723 | |
f70e2e06 DH |
724 | /* serialise link/link calls to prevent parallel calls causing a cycle |
725 | * when linking two keyring in opposite orders */ | |
726 | if (type == &key_type_keyring) | |
553d603c DH |
727 | down_write(&keyring_serialise_link_sem); |
728 | ||
f70e2e06 | 729 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 | 730 | |
cab8eb59 | 731 | /* see if there's a matching key we can displace */ |
cab8eb59 | 732 | if (klist && klist->nkeys > 0) { |
cab8eb59 DH |
733 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { |
734 | if (klist->keys[loop]->type == type && | |
735 | strcmp(klist->keys[loop]->description, | |
f70e2e06 | 736 | description) == 0 |
cab8eb59 | 737 | ) { |
f70e2e06 DH |
738 | /* found a match - we'll replace this one with |
739 | * the new key */ | |
cab8eb59 DH |
740 | size = sizeof(struct key *) * klist->maxkeys; |
741 | size += sizeof(*klist); | |
742 | BUG_ON(size > PAGE_SIZE); | |
743 | ||
744 | ret = -ENOMEM; | |
48ad504e | 745 | nklist = kmemdup(klist, size, GFP_KERNEL); |
cab8eb59 | 746 | if (!nklist) |
f70e2e06 | 747 | goto error_sem; |
cab8eb59 | 748 | |
f70e2e06 DH |
749 | /* note replacement slot */ |
750 | klist->delkey = nklist->delkey = loop; | |
ceb73c12 | 751 | prealloc = (unsigned long)nklist; |
cab8eb59 DH |
752 | goto done; |
753 | } | |
754 | } | |
755 | } | |
756 | ||
1da177e4 LT |
757 | /* check that we aren't going to overrun the user's quota */ |
758 | ret = key_payload_reserve(keyring, | |
759 | keyring->datalen + KEYQUOTA_LINK_BYTES); | |
760 | if (ret < 0) | |
f70e2e06 | 761 | goto error_sem; |
1da177e4 | 762 | |
1da177e4 | 763 | if (klist && klist->nkeys < klist->maxkeys) { |
f70e2e06 DH |
764 | /* there's sufficient slack space to append directly */ |
765 | nklist = NULL; | |
ceb73c12 | 766 | prealloc = KEY_LINK_FIXQUOTA; |
512ea3bc | 767 | } else { |
1da177e4 LT |
768 | /* grow the key list */ |
769 | max = 4; | |
770 | if (klist) | |
771 | max += klist->maxkeys; | |
772 | ||
773 | ret = -ENFILE; | |
4be929be | 774 | if (max > USHRT_MAX - 1) |
f70e2e06 | 775 | goto error_quota; |
a4014d8f | 776 | size = sizeof(*klist) + sizeof(struct key *) * max; |
1da177e4 | 777 | if (size > PAGE_SIZE) |
f70e2e06 | 778 | goto error_quota; |
1da177e4 LT |
779 | |
780 | ret = -ENOMEM; | |
781 | nklist = kmalloc(size, GFP_KERNEL); | |
782 | if (!nklist) | |
f70e2e06 | 783 | goto error_quota; |
1da177e4 | 784 | |
f70e2e06 | 785 | nklist->maxkeys = max; |
1da177e4 | 786 | if (klist) { |
f70e2e06 | 787 | memcpy(nklist->keys, klist->keys, |
1da177e4 | 788 | sizeof(struct key *) * klist->nkeys); |
f70e2e06 DH |
789 | nklist->delkey = klist->nkeys; |
790 | nklist->nkeys = klist->nkeys + 1; | |
4be929be | 791 | klist->delkey = USHRT_MAX; |
f70e2e06 DH |
792 | } else { |
793 | nklist->nkeys = 1; | |
794 | nklist->delkey = 0; | |
1da177e4 LT |
795 | } |
796 | ||
797 | /* add the key into the new space */ | |
f70e2e06 | 798 | nklist->keys[nklist->delkey] = NULL; |
1da177e4 LT |
799 | } |
800 | ||
ceb73c12 | 801 | prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA; |
cab8eb59 | 802 | done: |
ceb73c12 | 803 | *_prealloc = prealloc; |
f70e2e06 DH |
804 | kleave(" = 0"); |
805 | return 0; | |
1da177e4 | 806 | |
f70e2e06 | 807 | error_quota: |
1da177e4 LT |
808 | /* undo the quota changes */ |
809 | key_payload_reserve(keyring, | |
810 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
f70e2e06 DH |
811 | error_sem: |
812 | if (type == &key_type_keyring) | |
813 | up_write(&keyring_serialise_link_sem); | |
814 | error_krsem: | |
815 | up_write(&keyring->sem); | |
816 | kleave(" = %d", ret); | |
817 | return ret; | |
818 | } | |
1da177e4 | 819 | |
f70e2e06 | 820 | /* |
973c9f4f DH |
821 | * Check already instantiated keys aren't going to be a problem. |
822 | * | |
823 | * The caller must have called __key_link_begin(). Don't need to call this for | |
824 | * keys that were created since __key_link_begin() was called. | |
f70e2e06 DH |
825 | */ |
826 | int __key_link_check_live_key(struct key *keyring, struct key *key) | |
827 | { | |
828 | if (key->type == &key_type_keyring) | |
829 | /* check that we aren't going to create a cycle by linking one | |
830 | * keyring to another */ | |
831 | return keyring_detect_cycle(keyring, key); | |
832 | return 0; | |
833 | } | |
834 | ||
835 | /* | |
973c9f4f DH |
836 | * Link a key into to a keyring. |
837 | * | |
838 | * Must be called with __key_link_begin() having being called. Discards any | |
839 | * already extant link to matching key if there is one, so that each keyring | |
840 | * holds at most one link to any given key of a particular type+description | |
841 | * combination. | |
f70e2e06 DH |
842 | */ |
843 | void __key_link(struct key *keyring, struct key *key, | |
ceb73c12 | 844 | unsigned long *_prealloc) |
f70e2e06 DH |
845 | { |
846 | struct keyring_list *klist, *nklist; | |
847 | ||
ceb73c12 DH |
848 | nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA); |
849 | *_prealloc = 0; | |
f70e2e06 DH |
850 | |
851 | kenter("%d,%d,%p", keyring->serial, key->serial, nklist); | |
852 | ||
853 | klist = rcu_dereference_protected(keyring->payload.subscriptions, | |
854 | rwsem_is_locked(&keyring->sem)); | |
855 | ||
856 | atomic_inc(&key->usage); | |
857 | ||
858 | /* there's a matching key we can displace or an empty slot in a newly | |
859 | * allocated list we can fill */ | |
860 | if (nklist) { | |
861 | kdebug("replace %hu/%hu/%hu", | |
862 | nklist->delkey, nklist->nkeys, nklist->maxkeys); | |
863 | ||
864 | nklist->keys[nklist->delkey] = key; | |
865 | ||
866 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); | |
867 | ||
868 | /* dispose of the old keyring list and, if there was one, the | |
869 | * displaced key */ | |
870 | if (klist) { | |
871 | kdebug("dispose %hu/%hu/%hu", | |
872 | klist->delkey, klist->nkeys, klist->maxkeys); | |
873 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
874 | } | |
875 | } else { | |
876 | /* there's sufficient slack space to append directly */ | |
877 | klist->keys[klist->nkeys] = key; | |
878 | smp_wmb(); | |
879 | klist->nkeys++; | |
880 | } | |
881 | } | |
882 | ||
883 | /* | |
973c9f4f DH |
884 | * Finish linking a key into to a keyring. |
885 | * | |
886 | * Must be called with __key_link_begin() having being called. | |
f70e2e06 DH |
887 | */ |
888 | void __key_link_end(struct key *keyring, struct key_type *type, | |
ceb73c12 | 889 | unsigned long prealloc) |
f70e2e06 DH |
890 | __releases(&keyring->sem) |
891 | { | |
892 | BUG_ON(type == NULL); | |
893 | BUG_ON(type->name == NULL); | |
ceb73c12 | 894 | kenter("%d,%s,%lx", keyring->serial, type->name, prealloc); |
f70e2e06 DH |
895 | |
896 | if (type == &key_type_keyring) | |
897 | up_write(&keyring_serialise_link_sem); | |
898 | ||
899 | if (prealloc) { | |
ceb73c12 DH |
900 | if (prealloc & KEY_LINK_FIXQUOTA) |
901 | key_payload_reserve(keyring, | |
902 | keyring->datalen - | |
903 | KEYQUOTA_LINK_BYTES); | |
904 | kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA)); | |
f70e2e06 DH |
905 | } |
906 | up_write(&keyring->sem); | |
907 | } | |
1da177e4 | 908 | |
973c9f4f DH |
909 | /** |
910 | * key_link - Link a key to a keyring | |
911 | * @keyring: The keyring to make the link in. | |
912 | * @key: The key to link to. | |
913 | * | |
914 | * Make a link in a keyring to a key, such that the keyring holds a reference | |
915 | * on that key and the key can potentially be found by searching that keyring. | |
916 | * | |
917 | * This function will write-lock the keyring's semaphore and will consume some | |
918 | * of the user's key data quota to hold the link. | |
919 | * | |
920 | * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, | |
921 | * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is | |
922 | * full, -EDQUOT if there is insufficient key data quota remaining to add | |
923 | * another link or -ENOMEM if there's insufficient memory. | |
924 | * | |
925 | * It is assumed that the caller has checked that it is permitted for a link to | |
926 | * be made (the keyring should have Write permission and the key Link | |
927 | * permission). | |
1da177e4 LT |
928 | */ |
929 | int key_link(struct key *keyring, struct key *key) | |
930 | { | |
ceb73c12 | 931 | unsigned long prealloc; |
1da177e4 LT |
932 | int ret; |
933 | ||
934 | key_check(keyring); | |
935 | key_check(key); | |
936 | ||
f70e2e06 DH |
937 | ret = __key_link_begin(keyring, key->type, key->description, &prealloc); |
938 | if (ret == 0) { | |
939 | ret = __key_link_check_live_key(keyring, key); | |
940 | if (ret == 0) | |
941 | __key_link(keyring, key, &prealloc); | |
942 | __key_link_end(keyring, key->type, prealloc); | |
943 | } | |
1da177e4 LT |
944 | |
945 | return ret; | |
f70e2e06 | 946 | } |
1da177e4 LT |
947 | EXPORT_SYMBOL(key_link); |
948 | ||
973c9f4f DH |
949 | /** |
950 | * key_unlink - Unlink the first link to a key from a keyring. | |
951 | * @keyring: The keyring to remove the link from. | |
952 | * @key: The key the link is to. | |
953 | * | |
954 | * Remove a link from a keyring to a key. | |
955 | * | |
956 | * This function will write-lock the keyring's semaphore. | |
957 | * | |
958 | * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if | |
959 | * the key isn't linked to by the keyring or -ENOMEM if there's insufficient | |
960 | * memory. | |
961 | * | |
962 | * It is assumed that the caller has checked that it is permitted for a link to | |
963 | * be removed (the keyring should have Write permission; no permissions are | |
964 | * required on the key). | |
1da177e4 LT |
965 | */ |
966 | int key_unlink(struct key *keyring, struct key *key) | |
967 | { | |
76d8aeab | 968 | struct keyring_list *klist, *nklist; |
1da177e4 LT |
969 | int loop, ret; |
970 | ||
971 | key_check(keyring); | |
972 | key_check(key); | |
973 | ||
974 | ret = -ENOTDIR; | |
975 | if (keyring->type != &key_type_keyring) | |
976 | goto error; | |
977 | ||
978 | down_write(&keyring->sem); | |
979 | ||
f0641cba | 980 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
981 | if (klist) { |
982 | /* search the keyring for the key */ | |
983 | for (loop = 0; loop < klist->nkeys; loop++) | |
984 | if (klist->keys[loop] == key) | |
985 | goto key_is_present; | |
986 | } | |
987 | ||
988 | up_write(&keyring->sem); | |
989 | ret = -ENOENT; | |
990 | goto error; | |
991 | ||
76d8aeab DH |
992 | key_is_present: |
993 | /* we need to copy the key list for RCU purposes */ | |
a4014d8f DH |
994 | nklist = kmalloc(sizeof(*klist) + |
995 | sizeof(struct key *) * klist->maxkeys, | |
76d8aeab DH |
996 | GFP_KERNEL); |
997 | if (!nklist) | |
998 | goto nomem; | |
999 | nklist->maxkeys = klist->maxkeys; | |
1000 | nklist->nkeys = klist->nkeys - 1; | |
1001 | ||
1002 | if (loop > 0) | |
1003 | memcpy(&nklist->keys[0], | |
1004 | &klist->keys[0], | |
a4014d8f | 1005 | loop * sizeof(struct key *)); |
76d8aeab DH |
1006 | |
1007 | if (loop < nklist->nkeys) | |
1008 | memcpy(&nklist->keys[loop], | |
1009 | &klist->keys[loop + 1], | |
a4014d8f | 1010 | (nklist->nkeys - loop) * sizeof(struct key *)); |
76d8aeab | 1011 | |
1da177e4 LT |
1012 | /* adjust the user's quota */ |
1013 | key_payload_reserve(keyring, | |
1014 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
1015 | ||
76d8aeab | 1016 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
1da177e4 | 1017 | |
76d8aeab | 1018 | up_write(&keyring->sem); |
1da177e4 | 1019 | |
76d8aeab DH |
1020 | /* schedule for later cleanup */ |
1021 | klist->delkey = loop; | |
1022 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
1da177e4 | 1023 | |
1da177e4 LT |
1024 | ret = 0; |
1025 | ||
76d8aeab | 1026 | error: |
1da177e4 | 1027 | return ret; |
76d8aeab DH |
1028 | nomem: |
1029 | ret = -ENOMEM; | |
1030 | up_write(&keyring->sem); | |
1031 | goto error; | |
a8b17ed0 | 1032 | } |
1da177e4 LT |
1033 | EXPORT_SYMBOL(key_unlink); |
1034 | ||
76d8aeab | 1035 | /* |
973c9f4f DH |
1036 | * Dispose of a keyring list after the RCU grace period, releasing the keys it |
1037 | * links to. | |
76d8aeab DH |
1038 | */ |
1039 | static void keyring_clear_rcu_disposal(struct rcu_head *rcu) | |
1040 | { | |
1041 | struct keyring_list *klist; | |
1042 | int loop; | |
1043 | ||
1044 | klist = container_of(rcu, struct keyring_list, rcu); | |
1045 | ||
1046 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
1047 | key_put(klist->keys[loop]); | |
1048 | ||
1049 | kfree(klist); | |
a8b17ed0 | 1050 | } |
76d8aeab | 1051 | |
973c9f4f DH |
1052 | /** |
1053 | * keyring_clear - Clear a keyring | |
1054 | * @keyring: The keyring to clear. | |
1055 | * | |
1056 | * Clear the contents of the specified keyring. | |
1057 | * | |
1058 | * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring. | |
1da177e4 LT |
1059 | */ |
1060 | int keyring_clear(struct key *keyring) | |
1061 | { | |
1062 | struct keyring_list *klist; | |
76d8aeab | 1063 | int ret; |
1da177e4 LT |
1064 | |
1065 | ret = -ENOTDIR; | |
1066 | if (keyring->type == &key_type_keyring) { | |
1067 | /* detach the pointer block with the locks held */ | |
1068 | down_write(&keyring->sem); | |
1069 | ||
f0641cba | 1070 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
1071 | if (klist) { |
1072 | /* adjust the quota */ | |
1073 | key_payload_reserve(keyring, | |
1074 | sizeof(struct keyring_list)); | |
1075 | ||
76d8aeab DH |
1076 | rcu_assign_pointer(keyring->payload.subscriptions, |
1077 | NULL); | |
1da177e4 LT |
1078 | } |
1079 | ||
1080 | up_write(&keyring->sem); | |
1081 | ||
1082 | /* free the keys after the locks have been dropped */ | |
76d8aeab DH |
1083 | if (klist) |
1084 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1da177e4 LT |
1085 | |
1086 | ret = 0; | |
1087 | } | |
1088 | ||
1089 | return ret; | |
a8b17ed0 | 1090 | } |
1da177e4 | 1091 | EXPORT_SYMBOL(keyring_clear); |
31204ed9 | 1092 | |
31204ed9 | 1093 | /* |
973c9f4f DH |
1094 | * Dispose of the links from a revoked keyring. |
1095 | * | |
1096 | * This is called with the key sem write-locked. | |
31204ed9 DH |
1097 | */ |
1098 | static void keyring_revoke(struct key *keyring) | |
1099 | { | |
f0641cba DH |
1100 | struct keyring_list *klist; |
1101 | ||
1102 | klist = rcu_dereference_locked_keyring(keyring); | |
31204ed9 DH |
1103 | |
1104 | /* adjust the quota */ | |
1105 | key_payload_reserve(keyring, 0); | |
1106 | ||
1107 | if (klist) { | |
1108 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1109 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1110 | } | |
a8b17ed0 | 1111 | } |
5d135440 DH |
1112 | |
1113 | /* | |
973c9f4f | 1114 | * Determine whether a key is dead. |
5d135440 DH |
1115 | */ |
1116 | static bool key_is_dead(struct key *key, time_t limit) | |
1117 | { | |
1118 | return test_bit(KEY_FLAG_DEAD, &key->flags) || | |
1119 | (key->expiry > 0 && key->expiry <= limit); | |
1120 | } | |
1121 | ||
1122 | /* | |
973c9f4f DH |
1123 | * Collect garbage from the contents of a keyring, replacing the old list with |
1124 | * a new one with the pointers all shuffled down. | |
1125 | * | |
1126 | * Dead keys are classed as oned that are flagged as being dead or are revoked, | |
1127 | * expired or negative keys that were revoked or expired before the specified | |
1128 | * limit. | |
5d135440 DH |
1129 | */ |
1130 | void keyring_gc(struct key *keyring, time_t limit) | |
1131 | { | |
1132 | struct keyring_list *klist, *new; | |
1133 | struct key *key; | |
1134 | int loop, keep, max; | |
1135 | ||
c08ef808 | 1136 | kenter("{%x,%s}", key_serial(keyring), keyring->description); |
5d135440 DH |
1137 | |
1138 | down_write(&keyring->sem); | |
1139 | ||
f0641cba | 1140 | klist = rcu_dereference_locked_keyring(keyring); |
5d135440 | 1141 | if (!klist) |
c08ef808 | 1142 | goto no_klist; |
5d135440 DH |
1143 | |
1144 | /* work out how many subscriptions we're keeping */ | |
1145 | keep = 0; | |
1146 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
c08ef808 | 1147 | if (!key_is_dead(klist->keys[loop], limit)) |
5d135440 DH |
1148 | keep++; |
1149 | ||
1150 | if (keep == klist->nkeys) | |
1151 | goto just_return; | |
1152 | ||
1153 | /* allocate a new keyring payload */ | |
1154 | max = roundup(keep, 4); | |
1155 | new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *), | |
1156 | GFP_KERNEL); | |
1157 | if (!new) | |
c08ef808 | 1158 | goto nomem; |
5d135440 DH |
1159 | new->maxkeys = max; |
1160 | new->nkeys = 0; | |
1161 | new->delkey = 0; | |
1162 | ||
1163 | /* install the live keys | |
1164 | * - must take care as expired keys may be updated back to life | |
1165 | */ | |
1166 | keep = 0; | |
1167 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { | |
1168 | key = klist->keys[loop]; | |
1169 | if (!key_is_dead(key, limit)) { | |
1170 | if (keep >= max) | |
1171 | goto discard_new; | |
1172 | new->keys[keep++] = key_get(key); | |
1173 | } | |
1174 | } | |
1175 | new->nkeys = keep; | |
1176 | ||
1177 | /* adjust the quota */ | |
1178 | key_payload_reserve(keyring, | |
1179 | sizeof(struct keyring_list) + | |
1180 | KEYQUOTA_LINK_BYTES * keep); | |
1181 | ||
1182 | if (keep == 0) { | |
1183 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1184 | kfree(new); | |
1185 | } else { | |
1186 | rcu_assign_pointer(keyring->payload.subscriptions, new); | |
1187 | } | |
1188 | ||
1189 | up_write(&keyring->sem); | |
1190 | ||
1191 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1192 | kleave(" [yes]"); | |
1193 | return; | |
1194 | ||
1195 | discard_new: | |
1196 | new->nkeys = keep; | |
1197 | keyring_clear_rcu_disposal(&new->rcu); | |
c08ef808 DH |
1198 | up_write(&keyring->sem); |
1199 | kleave(" [discard]"); | |
1200 | return; | |
1201 | ||
5d135440 DH |
1202 | just_return: |
1203 | up_write(&keyring->sem); | |
c08ef808 DH |
1204 | kleave(" [no dead]"); |
1205 | return; | |
1206 | ||
1207 | no_klist: | |
1208 | up_write(&keyring->sem); | |
1209 | kleave(" [no_klist]"); | |
1210 | return; | |
1211 | ||
1212 | nomem: | |
1213 | up_write(&keyring->sem); | |
1214 | kleave(" [oom]"); | |
5d135440 | 1215 | } |