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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 | 157 | klist = rcu_dereference_check(keyring->payload.subscriptions, |
e7b0a61b | 158 | atomic_read(&keyring->usage) == 0); |
1da177e4 LT |
159 | if (klist) { |
160 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
161 | key_put(klist->keys[loop]); | |
162 | kfree(klist); | |
163 | } | |
a8b17ed0 | 164 | } |
1da177e4 | 165 | |
1da177e4 | 166 | /* |
973c9f4f | 167 | * Describe a keyring for /proc. |
1da177e4 LT |
168 | */ |
169 | static void keyring_describe(const struct key *keyring, struct seq_file *m) | |
170 | { | |
171 | struct keyring_list *klist; | |
172 | ||
c8563473 | 173 | if (keyring->description) |
1da177e4 | 174 | seq_puts(m, keyring->description); |
c8563473 | 175 | else |
1da177e4 | 176 | seq_puts(m, "[anon]"); |
1da177e4 | 177 | |
78b7280c DH |
178 | if (key_is_instantiated(keyring)) { |
179 | rcu_read_lock(); | |
180 | klist = rcu_dereference(keyring->payload.subscriptions); | |
181 | if (klist) | |
182 | seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys); | |
183 | else | |
184 | seq_puts(m, ": empty"); | |
185 | rcu_read_unlock(); | |
186 | } | |
a8b17ed0 | 187 | } |
1da177e4 | 188 | |
1da177e4 | 189 | /* |
973c9f4f DH |
190 | * Read a list of key IDs from the keyring's contents in binary form |
191 | * | |
192 | * The keyring's semaphore is read-locked by the caller. | |
1da177e4 LT |
193 | */ |
194 | static long keyring_read(const struct key *keyring, | |
195 | char __user *buffer, size_t buflen) | |
196 | { | |
197 | struct keyring_list *klist; | |
198 | struct key *key; | |
199 | size_t qty, tmp; | |
200 | int loop, ret; | |
201 | ||
202 | ret = 0; | |
f0641cba | 203 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
204 | if (klist) { |
205 | /* calculate how much data we could return */ | |
206 | qty = klist->nkeys * sizeof(key_serial_t); | |
207 | ||
208 | if (buffer && buflen > 0) { | |
209 | if (buflen > qty) | |
210 | buflen = qty; | |
211 | ||
212 | /* copy the IDs of the subscribed keys into the | |
213 | * buffer */ | |
214 | ret = -EFAULT; | |
215 | ||
216 | for (loop = 0; loop < klist->nkeys; loop++) { | |
217 | key = klist->keys[loop]; | |
218 | ||
219 | tmp = sizeof(key_serial_t); | |
220 | if (tmp > buflen) | |
221 | tmp = buflen; | |
222 | ||
223 | if (copy_to_user(buffer, | |
224 | &key->serial, | |
225 | tmp) != 0) | |
226 | goto error; | |
227 | ||
228 | buflen -= tmp; | |
229 | if (buflen == 0) | |
230 | break; | |
231 | buffer += tmp; | |
232 | } | |
233 | } | |
234 | ||
235 | ret = qty; | |
236 | } | |
237 | ||
c5b60b5e | 238 | error: |
1da177e4 | 239 | return ret; |
a8b17ed0 | 240 | } |
1da177e4 | 241 | |
1da177e4 | 242 | /* |
973c9f4f | 243 | * Allocate a keyring and link into the destination keyring. |
1da177e4 LT |
244 | */ |
245 | struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, | |
d84f4f99 | 246 | const struct cred *cred, unsigned long flags, |
d720024e | 247 | struct key *dest) |
1da177e4 LT |
248 | { |
249 | struct key *keyring; | |
250 | int ret; | |
251 | ||
252 | keyring = key_alloc(&key_type_keyring, description, | |
d84f4f99 | 253 | uid, gid, cred, |
29db9190 | 254 | (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, |
7e047ef5 | 255 | flags); |
1da177e4 LT |
256 | |
257 | if (!IS_ERR(keyring)) { | |
3e30148c | 258 | ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); |
1da177e4 LT |
259 | if (ret < 0) { |
260 | key_put(keyring); | |
261 | keyring = ERR_PTR(ret); | |
262 | } | |
263 | } | |
264 | ||
265 | return keyring; | |
a8b17ed0 | 266 | } |
1da177e4 | 267 | |
973c9f4f DH |
268 | /** |
269 | * keyring_search_aux - Search a keyring tree for a key matching some criteria | |
270 | * @keyring_ref: A pointer to the keyring with possession indicator. | |
271 | * @cred: The credentials to use for permissions checks. | |
272 | * @type: The type of key to search for. | |
273 | * @description: Parameter for @match. | |
274 | * @match: Function to rule on whether or not a key is the one required. | |
78b7280c | 275 | * @no_state_check: Don't check if a matching key is bad |
973c9f4f DH |
276 | * |
277 | * Search the supplied keyring tree for a key that matches the criteria given. | |
278 | * The root keyring and any linked keyrings must grant Search permission to the | |
279 | * caller to be searchable and keys can only be found if they too grant Search | |
280 | * to the caller. The possession flag on the root keyring pointer controls use | |
281 | * of the possessor bits in permissions checking of the entire tree. In | |
282 | * addition, the LSM gets to forbid keyring searches and key matches. | |
283 | * | |
284 | * The search is performed as a breadth-then-depth search up to the prescribed | |
285 | * limit (KEYRING_SEARCH_MAX_DEPTH). | |
286 | * | |
287 | * Keys are matched to the type provided and are then filtered by the match | |
288 | * function, which is given the description to use in any way it sees fit. The | |
289 | * match function may use any attributes of a key that it wishes to to | |
290 | * determine the match. Normally the match function from the key type would be | |
291 | * used. | |
292 | * | |
293 | * RCU is used to prevent the keyring key lists from disappearing without the | |
294 | * need to take lots of locks. | |
295 | * | |
296 | * Returns a pointer to the found key and increments the key usage count if | |
297 | * successful; -EAGAIN if no matching keys were found, or if expired or revoked | |
298 | * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the | |
299 | * specified keyring wasn't a keyring. | |
300 | * | |
301 | * In the case of a successful return, the possession attribute from | |
302 | * @keyring_ref is propagated to the returned key reference. | |
1da177e4 | 303 | */ |
664cceb0 | 304 | key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
d84f4f99 | 305 | const struct cred *cred, |
664cceb0 DH |
306 | struct key_type *type, |
307 | const void *description, | |
78b7280c DH |
308 | key_match_func_t match, |
309 | bool no_state_check) | |
1da177e4 LT |
310 | { |
311 | struct { | |
76d8aeab | 312 | struct keyring_list *keylist; |
1da177e4 LT |
313 | int kix; |
314 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
315 | ||
316 | struct keyring_list *keylist; | |
317 | struct timespec now; | |
dceba994 | 318 | unsigned long possessed, kflags; |
664cceb0 DH |
319 | struct key *keyring, *key; |
320 | key_ref_t key_ref; | |
1da177e4 | 321 | long err; |
76d8aeab | 322 | int sp, kix; |
1da177e4 | 323 | |
664cceb0 DH |
324 | keyring = key_ref_to_ptr(keyring_ref); |
325 | possessed = is_key_possessed(keyring_ref); | |
1da177e4 LT |
326 | key_check(keyring); |
327 | ||
328 | /* top keyring must have search permission to begin the search */ | |
512ea3bc | 329 | err = key_task_permission(keyring_ref, cred, KEY_SEARCH); |
29db9190 DH |
330 | if (err < 0) { |
331 | key_ref = ERR_PTR(err); | |
1da177e4 | 332 | goto error; |
29db9190 | 333 | } |
1da177e4 | 334 | |
664cceb0 | 335 | key_ref = ERR_PTR(-ENOTDIR); |
1da177e4 LT |
336 | if (keyring->type != &key_type_keyring) |
337 | goto error; | |
338 | ||
664cceb0 DH |
339 | rcu_read_lock(); |
340 | ||
1da177e4 LT |
341 | now = current_kernel_time(); |
342 | err = -EAGAIN; | |
343 | sp = 0; | |
344 | ||
dceba994 KC |
345 | /* firstly we should check to see if this top-level keyring is what we |
346 | * are looking for */ | |
347 | key_ref = ERR_PTR(-EAGAIN); | |
348 | kflags = keyring->flags; | |
349 | if (keyring->type == type && match(keyring, description)) { | |
350 | key = keyring; | |
78b7280c DH |
351 | if (no_state_check) |
352 | goto found; | |
dceba994 KC |
353 | |
354 | /* check it isn't negative and hasn't expired or been | |
355 | * revoked */ | |
356 | if (kflags & (1 << KEY_FLAG_REVOKED)) | |
357 | goto error_2; | |
358 | if (key->expiry && now.tv_sec >= key->expiry) | |
359 | goto error_2; | |
fdd1b945 | 360 | key_ref = ERR_PTR(key->type_data.reject_error); |
dceba994 KC |
361 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) |
362 | goto error_2; | |
363 | goto found; | |
364 | } | |
365 | ||
366 | /* otherwise, the top keyring must not be revoked, expired, or | |
367 | * negatively instantiated if we are to search it */ | |
368 | key_ref = ERR_PTR(-EAGAIN); | |
369 | if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) || | |
370 | (keyring->expiry && now.tv_sec >= keyring->expiry)) | |
371 | goto error_2; | |
372 | ||
1da177e4 | 373 | /* start processing a new keyring */ |
664cceb0 | 374 | descend: |
76d8aeab | 375 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
376 | goto not_this_keyring; |
377 | ||
76d8aeab | 378 | keylist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
379 | if (!keylist) |
380 | goto not_this_keyring; | |
381 | ||
382 | /* iterate through the keys in this keyring first */ | |
383 | for (kix = 0; kix < keylist->nkeys; kix++) { | |
384 | key = keylist->keys[kix]; | |
dceba994 | 385 | kflags = key->flags; |
1da177e4 LT |
386 | |
387 | /* ignore keys not of this type */ | |
388 | if (key->type != type) | |
389 | continue; | |
390 | ||
391 | /* skip revoked keys and expired keys */ | |
78b7280c DH |
392 | if (!no_state_check) { |
393 | if (kflags & (1 << KEY_FLAG_REVOKED)) | |
394 | continue; | |
1da177e4 | 395 | |
78b7280c DH |
396 | if (key->expiry && now.tv_sec >= key->expiry) |
397 | continue; | |
398 | } | |
1da177e4 LT |
399 | |
400 | /* keys that don't match */ | |
401 | if (!match(key, description)) | |
402 | continue; | |
403 | ||
404 | /* key must have search permissions */ | |
29db9190 | 405 | if (key_task_permission(make_key_ref(key, possessed), |
d84f4f99 | 406 | cred, KEY_SEARCH) < 0) |
1da177e4 LT |
407 | continue; |
408 | ||
78b7280c DH |
409 | if (no_state_check) |
410 | goto found; | |
411 | ||
dceba994 KC |
412 | /* we set a different error code if we pass a negative key */ |
413 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) { | |
fdd1b945 | 414 | err = key->type_data.reject_error; |
1da177e4 LT |
415 | continue; |
416 | } | |
417 | ||
418 | goto found; | |
419 | } | |
420 | ||
421 | /* search through the keyrings nested in this one */ | |
422 | kix = 0; | |
664cceb0 | 423 | ascend: |
76d8aeab | 424 | for (; kix < keylist->nkeys; kix++) { |
1da177e4 LT |
425 | key = keylist->keys[kix]; |
426 | if (key->type != &key_type_keyring) | |
76d8aeab | 427 | continue; |
1da177e4 LT |
428 | |
429 | /* recursively search nested keyrings | |
430 | * - only search keyrings for which we have search permission | |
431 | */ | |
432 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
76d8aeab | 433 | continue; |
1da177e4 | 434 | |
0f6ed7c2 | 435 | if (key_task_permission(make_key_ref(key, possessed), |
d84f4f99 | 436 | cred, KEY_SEARCH) < 0) |
76d8aeab | 437 | continue; |
1da177e4 LT |
438 | |
439 | /* stack the current position */ | |
76d8aeab | 440 | stack[sp].keylist = keylist; |
1da177e4 LT |
441 | stack[sp].kix = kix; |
442 | sp++; | |
443 | ||
444 | /* begin again with the new keyring */ | |
445 | keyring = key; | |
446 | goto descend; | |
1da177e4 LT |
447 | } |
448 | ||
449 | /* the keyring we're looking at was disqualified or didn't contain a | |
450 | * matching key */ | |
664cceb0 | 451 | not_this_keyring: |
1da177e4 LT |
452 | if (sp > 0) { |
453 | /* resume the processing of a keyring higher up in the tree */ | |
454 | sp--; | |
76d8aeab | 455 | keylist = stack[sp].keylist; |
1da177e4 LT |
456 | kix = stack[sp].kix + 1; |
457 | goto ascend; | |
458 | } | |
459 | ||
664cceb0 DH |
460 | key_ref = ERR_PTR(err); |
461 | goto error_2; | |
1da177e4 LT |
462 | |
463 | /* we found a viable match */ | |
664cceb0 | 464 | found: |
1da177e4 | 465 | atomic_inc(&key->usage); |
1da177e4 | 466 | key_check(key); |
664cceb0 DH |
467 | key_ref = make_key_ref(key, possessed); |
468 | error_2: | |
76d8aeab | 469 | rcu_read_unlock(); |
664cceb0 DH |
470 | error: |
471 | return key_ref; | |
a8b17ed0 | 472 | } |
1da177e4 | 473 | |
973c9f4f DH |
474 | /** |
475 | * keyring_search - Search the supplied keyring tree for a matching key | |
476 | * @keyring: The root of the keyring tree to be searched. | |
477 | * @type: The type of keyring we want to find. | |
478 | * @description: The name of the keyring we want to find. | |
479 | * | |
480 | * As keyring_search_aux() above, but using the current task's credentials and | |
481 | * type's default matching function. | |
1da177e4 | 482 | */ |
664cceb0 DH |
483 | key_ref_t keyring_search(key_ref_t keyring, |
484 | struct key_type *type, | |
485 | const char *description) | |
1da177e4 | 486 | { |
3e30148c DH |
487 | if (!type->match) |
488 | return ERR_PTR(-ENOKEY); | |
489 | ||
d84f4f99 | 490 | return keyring_search_aux(keyring, current->cred, |
78b7280c | 491 | type, description, type->match, false); |
a8b17ed0 | 492 | } |
1da177e4 LT |
493 | EXPORT_SYMBOL(keyring_search); |
494 | ||
1da177e4 | 495 | /* |
973c9f4f DH |
496 | * Search the given keyring only (no recursion). |
497 | * | |
498 | * The caller must guarantee that the keyring is a keyring and that the | |
499 | * permission is granted to search the keyring as no check is made here. | |
500 | * | |
501 | * RCU is used to make it unnecessary to lock the keyring key list here. | |
502 | * | |
503 | * Returns a pointer to the found key with usage count incremented if | |
504 | * successful and returns -ENOKEY if not found. Revoked keys and keys not | |
505 | * providing the requested permission are skipped over. | |
506 | * | |
507 | * If successful, the possession indicator is propagated from the keyring ref | |
508 | * to the returned key reference. | |
1da177e4 | 509 | */ |
664cceb0 DH |
510 | key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
511 | const struct key_type *ktype, | |
512 | const char *description, | |
513 | key_perm_t perm) | |
1da177e4 LT |
514 | { |
515 | struct keyring_list *klist; | |
664cceb0 DH |
516 | unsigned long possessed; |
517 | struct key *keyring, *key; | |
1da177e4 LT |
518 | int loop; |
519 | ||
664cceb0 DH |
520 | keyring = key_ref_to_ptr(keyring_ref); |
521 | possessed = is_key_possessed(keyring_ref); | |
522 | ||
76d8aeab DH |
523 | rcu_read_lock(); |
524 | ||
525 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
526 | if (klist) { |
527 | for (loop = 0; loop < klist->nkeys; loop++) { | |
528 | key = klist->keys[loop]; | |
529 | ||
530 | if (key->type == ktype && | |
3e30148c DH |
531 | (!key->type->match || |
532 | key->type->match(key, description)) && | |
664cceb0 | 533 | key_permission(make_key_ref(key, possessed), |
db1d1d57 | 534 | perm) == 0 && |
76d8aeab | 535 | !test_bit(KEY_FLAG_REVOKED, &key->flags) |
1da177e4 LT |
536 | ) |
537 | goto found; | |
538 | } | |
539 | } | |
540 | ||
664cceb0 DH |
541 | rcu_read_unlock(); |
542 | return ERR_PTR(-ENOKEY); | |
1da177e4 | 543 | |
c5b60b5e | 544 | found: |
1da177e4 | 545 | atomic_inc(&key->usage); |
76d8aeab | 546 | rcu_read_unlock(); |
664cceb0 | 547 | return make_key_ref(key, possessed); |
a8b17ed0 | 548 | } |
1da177e4 | 549 | |
1da177e4 | 550 | /* |
973c9f4f DH |
551 | * Find a keyring with the specified name. |
552 | * | |
553 | * All named keyrings in the current user namespace are searched, provided they | |
554 | * grant Search permission directly to the caller (unless this check is | |
555 | * skipped). Keyrings whose usage points have reached zero or who have been | |
556 | * revoked are skipped. | |
557 | * | |
558 | * Returns a pointer to the keyring with the keyring's refcount having being | |
559 | * incremented on success. -ENOKEY is returned if a key could not be found. | |
1da177e4 | 560 | */ |
69664cf1 | 561 | struct key *find_keyring_by_name(const char *name, bool skip_perm_check) |
1da177e4 LT |
562 | { |
563 | struct key *keyring; | |
564 | int bucket; | |
565 | ||
1da177e4 | 566 | if (!name) |
cea7daa3 | 567 | return ERR_PTR(-EINVAL); |
1da177e4 LT |
568 | |
569 | bucket = keyring_hash(name); | |
570 | ||
571 | read_lock(&keyring_name_lock); | |
572 | ||
573 | if (keyring_name_hash[bucket].next) { | |
574 | /* search this hash bucket for a keyring with a matching name | |
575 | * that's readable and that hasn't been revoked */ | |
576 | list_for_each_entry(keyring, | |
577 | &keyring_name_hash[bucket], | |
578 | type_data.link | |
579 | ) { | |
2ea190d0 SH |
580 | if (keyring->user->user_ns != current_user_ns()) |
581 | continue; | |
582 | ||
76d8aeab | 583 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
584 | continue; |
585 | ||
586 | if (strcmp(keyring->description, name) != 0) | |
587 | continue; | |
588 | ||
69664cf1 DH |
589 | if (!skip_perm_check && |
590 | key_permission(make_key_ref(keyring, 0), | |
0f6ed7c2 | 591 | KEY_SEARCH) < 0) |
1da177e4 LT |
592 | continue; |
593 | ||
cea7daa3 TO |
594 | /* we've got a match but we might end up racing with |
595 | * key_cleanup() if the keyring is currently 'dead' | |
596 | * (ie. it has a zero usage count) */ | |
597 | if (!atomic_inc_not_zero(&keyring->usage)) | |
598 | continue; | |
599 | goto out; | |
1da177e4 LT |
600 | } |
601 | } | |
602 | ||
1da177e4 | 603 | keyring = ERR_PTR(-ENOKEY); |
cea7daa3 TO |
604 | out: |
605 | read_unlock(&keyring_name_lock); | |
1da177e4 | 606 | return keyring; |
a8b17ed0 | 607 | } |
1da177e4 | 608 | |
1da177e4 | 609 | /* |
973c9f4f DH |
610 | * See if a cycle will will be created by inserting acyclic tree B in acyclic |
611 | * tree A at the topmost level (ie: as a direct child of A). | |
612 | * | |
613 | * Since we are adding B to A at the top level, checking for cycles should just | |
614 | * be a matter of seeing if node A is somewhere in tree B. | |
1da177e4 LT |
615 | */ |
616 | static int keyring_detect_cycle(struct key *A, struct key *B) | |
617 | { | |
618 | struct { | |
76d8aeab | 619 | struct keyring_list *keylist; |
1da177e4 LT |
620 | int kix; |
621 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
622 | ||
623 | struct keyring_list *keylist; | |
624 | struct key *subtree, *key; | |
625 | int sp, kix, ret; | |
626 | ||
76d8aeab DH |
627 | rcu_read_lock(); |
628 | ||
1da177e4 LT |
629 | ret = -EDEADLK; |
630 | if (A == B) | |
76d8aeab | 631 | goto cycle_detected; |
1da177e4 LT |
632 | |
633 | subtree = B; | |
634 | sp = 0; | |
635 | ||
636 | /* start processing a new keyring */ | |
c5b60b5e | 637 | descend: |
76d8aeab | 638 | if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
1da177e4 LT |
639 | goto not_this_keyring; |
640 | ||
76d8aeab | 641 | keylist = rcu_dereference(subtree->payload.subscriptions); |
1da177e4 LT |
642 | if (!keylist) |
643 | goto not_this_keyring; | |
644 | kix = 0; | |
645 | ||
c5b60b5e | 646 | ascend: |
1da177e4 LT |
647 | /* iterate through the remaining keys in this keyring */ |
648 | for (; kix < keylist->nkeys; kix++) { | |
649 | key = keylist->keys[kix]; | |
650 | ||
651 | if (key == A) | |
652 | goto cycle_detected; | |
653 | ||
654 | /* recursively check nested keyrings */ | |
655 | if (key->type == &key_type_keyring) { | |
656 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
657 | goto too_deep; | |
658 | ||
659 | /* stack the current position */ | |
76d8aeab | 660 | stack[sp].keylist = keylist; |
1da177e4 LT |
661 | stack[sp].kix = kix; |
662 | sp++; | |
663 | ||
664 | /* begin again with the new keyring */ | |
665 | subtree = key; | |
666 | goto descend; | |
667 | } | |
668 | } | |
669 | ||
670 | /* the keyring we're looking at was disqualified or didn't contain a | |
671 | * matching key */ | |
c5b60b5e | 672 | not_this_keyring: |
1da177e4 LT |
673 | if (sp > 0) { |
674 | /* resume the checking of a keyring higher up in the tree */ | |
675 | sp--; | |
76d8aeab | 676 | keylist = stack[sp].keylist; |
1da177e4 LT |
677 | kix = stack[sp].kix + 1; |
678 | goto ascend; | |
679 | } | |
680 | ||
681 | ret = 0; /* no cycles detected */ | |
682 | ||
c5b60b5e | 683 | error: |
76d8aeab | 684 | rcu_read_unlock(); |
1da177e4 LT |
685 | return ret; |
686 | ||
c5b60b5e | 687 | too_deep: |
1da177e4 | 688 | ret = -ELOOP; |
76d8aeab DH |
689 | goto error; |
690 | ||
c5b60b5e | 691 | cycle_detected: |
1da177e4 | 692 | ret = -EDEADLK; |
1da177e4 | 693 | goto error; |
a8b17ed0 | 694 | } |
1da177e4 | 695 | |
cab8eb59 | 696 | /* |
973c9f4f | 697 | * Dispose of a keyring list after the RCU grace period, freeing the unlinked |
cab8eb59 DH |
698 | * key |
699 | */ | |
700 | static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) | |
701 | { | |
702 | struct keyring_list *klist = | |
703 | container_of(rcu, struct keyring_list, rcu); | |
704 | ||
4be929be | 705 | if (klist->delkey != USHRT_MAX) |
f70e2e06 | 706 | key_put(klist->keys[klist->delkey]); |
cab8eb59 | 707 | kfree(klist); |
f70e2e06 | 708 | } |
cab8eb59 | 709 | |
1da177e4 | 710 | /* |
973c9f4f | 711 | * Preallocate memory so that a key can be linked into to a keyring. |
1da177e4 | 712 | */ |
f70e2e06 | 713 | int __key_link_begin(struct key *keyring, const struct key_type *type, |
ceb73c12 | 714 | const char *description, unsigned long *_prealloc) |
f70e2e06 | 715 | __acquires(&keyring->sem) |
1da177e4 LT |
716 | { |
717 | struct keyring_list *klist, *nklist; | |
ceb73c12 | 718 | unsigned long prealloc; |
1da177e4 LT |
719 | unsigned max; |
720 | size_t size; | |
cab8eb59 | 721 | int loop, ret; |
1da177e4 | 722 | |
f70e2e06 | 723 | kenter("%d,%s,%s,", key_serial(keyring), type->name, description); |
1da177e4 | 724 | |
1da177e4 | 725 | if (keyring->type != &key_type_keyring) |
f70e2e06 DH |
726 | return -ENOTDIR; |
727 | ||
728 | down_write(&keyring->sem); | |
729 | ||
730 | ret = -EKEYREVOKED; | |
731 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) | |
732 | goto error_krsem; | |
1da177e4 | 733 | |
f70e2e06 DH |
734 | /* serialise link/link calls to prevent parallel calls causing a cycle |
735 | * when linking two keyring in opposite orders */ | |
736 | if (type == &key_type_keyring) | |
553d603c DH |
737 | down_write(&keyring_serialise_link_sem); |
738 | ||
f70e2e06 | 739 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 | 740 | |
cab8eb59 | 741 | /* see if there's a matching key we can displace */ |
cab8eb59 | 742 | if (klist && klist->nkeys > 0) { |
cab8eb59 DH |
743 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { |
744 | if (klist->keys[loop]->type == type && | |
745 | strcmp(klist->keys[loop]->description, | |
f70e2e06 | 746 | description) == 0 |
cab8eb59 | 747 | ) { |
f70e2e06 DH |
748 | /* found a match - we'll replace this one with |
749 | * the new key */ | |
cab8eb59 DH |
750 | size = sizeof(struct key *) * klist->maxkeys; |
751 | size += sizeof(*klist); | |
752 | BUG_ON(size > PAGE_SIZE); | |
753 | ||
754 | ret = -ENOMEM; | |
48ad504e | 755 | nklist = kmemdup(klist, size, GFP_KERNEL); |
cab8eb59 | 756 | if (!nklist) |
f70e2e06 | 757 | goto error_sem; |
cab8eb59 | 758 | |
f70e2e06 DH |
759 | /* note replacement slot */ |
760 | klist->delkey = nklist->delkey = loop; | |
ceb73c12 | 761 | prealloc = (unsigned long)nklist; |
cab8eb59 DH |
762 | goto done; |
763 | } | |
764 | } | |
765 | } | |
766 | ||
1da177e4 LT |
767 | /* check that we aren't going to overrun the user's quota */ |
768 | ret = key_payload_reserve(keyring, | |
769 | keyring->datalen + KEYQUOTA_LINK_BYTES); | |
770 | if (ret < 0) | |
f70e2e06 | 771 | goto error_sem; |
1da177e4 | 772 | |
1da177e4 | 773 | if (klist && klist->nkeys < klist->maxkeys) { |
f70e2e06 DH |
774 | /* there's sufficient slack space to append directly */ |
775 | nklist = NULL; | |
ceb73c12 | 776 | prealloc = KEY_LINK_FIXQUOTA; |
512ea3bc | 777 | } else { |
1da177e4 LT |
778 | /* grow the key list */ |
779 | max = 4; | |
780 | if (klist) | |
781 | max += klist->maxkeys; | |
782 | ||
783 | ret = -ENFILE; | |
4be929be | 784 | if (max > USHRT_MAX - 1) |
f70e2e06 | 785 | goto error_quota; |
a4014d8f | 786 | size = sizeof(*klist) + sizeof(struct key *) * max; |
1da177e4 | 787 | if (size > PAGE_SIZE) |
f70e2e06 | 788 | goto error_quota; |
1da177e4 LT |
789 | |
790 | ret = -ENOMEM; | |
791 | nklist = kmalloc(size, GFP_KERNEL); | |
792 | if (!nklist) | |
f70e2e06 | 793 | goto error_quota; |
1da177e4 | 794 | |
f70e2e06 | 795 | nklist->maxkeys = max; |
1da177e4 | 796 | if (klist) { |
f70e2e06 | 797 | memcpy(nklist->keys, klist->keys, |
1da177e4 | 798 | sizeof(struct key *) * klist->nkeys); |
f70e2e06 DH |
799 | nklist->delkey = klist->nkeys; |
800 | nklist->nkeys = klist->nkeys + 1; | |
4be929be | 801 | klist->delkey = USHRT_MAX; |
f70e2e06 DH |
802 | } else { |
803 | nklist->nkeys = 1; | |
804 | nklist->delkey = 0; | |
1da177e4 LT |
805 | } |
806 | ||
807 | /* add the key into the new space */ | |
f70e2e06 | 808 | nklist->keys[nklist->delkey] = NULL; |
1da177e4 LT |
809 | } |
810 | ||
ceb73c12 | 811 | prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA; |
cab8eb59 | 812 | done: |
ceb73c12 | 813 | *_prealloc = prealloc; |
f70e2e06 DH |
814 | kleave(" = 0"); |
815 | return 0; | |
1da177e4 | 816 | |
f70e2e06 | 817 | error_quota: |
1da177e4 LT |
818 | /* undo the quota changes */ |
819 | key_payload_reserve(keyring, | |
820 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
f70e2e06 DH |
821 | error_sem: |
822 | if (type == &key_type_keyring) | |
823 | up_write(&keyring_serialise_link_sem); | |
824 | error_krsem: | |
825 | up_write(&keyring->sem); | |
826 | kleave(" = %d", ret); | |
827 | return ret; | |
828 | } | |
1da177e4 | 829 | |
f70e2e06 | 830 | /* |
973c9f4f DH |
831 | * Check already instantiated keys aren't going to be a problem. |
832 | * | |
833 | * The caller must have called __key_link_begin(). Don't need to call this for | |
834 | * keys that were created since __key_link_begin() was called. | |
f70e2e06 DH |
835 | */ |
836 | int __key_link_check_live_key(struct key *keyring, struct key *key) | |
837 | { | |
838 | if (key->type == &key_type_keyring) | |
839 | /* check that we aren't going to create a cycle by linking one | |
840 | * keyring to another */ | |
841 | return keyring_detect_cycle(keyring, key); | |
842 | return 0; | |
843 | } | |
844 | ||
845 | /* | |
973c9f4f DH |
846 | * Link a key into to a keyring. |
847 | * | |
848 | * Must be called with __key_link_begin() having being called. Discards any | |
849 | * already extant link to matching key if there is one, so that each keyring | |
850 | * holds at most one link to any given key of a particular type+description | |
851 | * combination. | |
f70e2e06 DH |
852 | */ |
853 | void __key_link(struct key *keyring, struct key *key, | |
ceb73c12 | 854 | unsigned long *_prealloc) |
f70e2e06 DH |
855 | { |
856 | struct keyring_list *klist, *nklist; | |
857 | ||
ceb73c12 DH |
858 | nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA); |
859 | *_prealloc = 0; | |
f70e2e06 DH |
860 | |
861 | kenter("%d,%d,%p", keyring->serial, key->serial, nklist); | |
862 | ||
6d528b08 | 863 | klist = rcu_dereference_locked_keyring(keyring); |
f70e2e06 DH |
864 | |
865 | atomic_inc(&key->usage); | |
866 | ||
867 | /* there's a matching key we can displace or an empty slot in a newly | |
868 | * allocated list we can fill */ | |
869 | if (nklist) { | |
870 | kdebug("replace %hu/%hu/%hu", | |
871 | nklist->delkey, nklist->nkeys, nklist->maxkeys); | |
872 | ||
873 | nklist->keys[nklist->delkey] = key; | |
874 | ||
875 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); | |
876 | ||
877 | /* dispose of the old keyring list and, if there was one, the | |
878 | * displaced key */ | |
879 | if (klist) { | |
880 | kdebug("dispose %hu/%hu/%hu", | |
881 | klist->delkey, klist->nkeys, klist->maxkeys); | |
882 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
883 | } | |
884 | } else { | |
885 | /* there's sufficient slack space to append directly */ | |
886 | klist->keys[klist->nkeys] = key; | |
887 | smp_wmb(); | |
888 | klist->nkeys++; | |
889 | } | |
890 | } | |
891 | ||
892 | /* | |
973c9f4f DH |
893 | * Finish linking a key into to a keyring. |
894 | * | |
895 | * Must be called with __key_link_begin() having being called. | |
f70e2e06 DH |
896 | */ |
897 | void __key_link_end(struct key *keyring, struct key_type *type, | |
ceb73c12 | 898 | unsigned long prealloc) |
f70e2e06 DH |
899 | __releases(&keyring->sem) |
900 | { | |
901 | BUG_ON(type == NULL); | |
902 | BUG_ON(type->name == NULL); | |
ceb73c12 | 903 | kenter("%d,%s,%lx", keyring->serial, type->name, prealloc); |
f70e2e06 DH |
904 | |
905 | if (type == &key_type_keyring) | |
906 | up_write(&keyring_serialise_link_sem); | |
907 | ||
908 | if (prealloc) { | |
ceb73c12 DH |
909 | if (prealloc & KEY_LINK_FIXQUOTA) |
910 | key_payload_reserve(keyring, | |
911 | keyring->datalen - | |
912 | KEYQUOTA_LINK_BYTES); | |
913 | kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA)); | |
f70e2e06 DH |
914 | } |
915 | up_write(&keyring->sem); | |
916 | } | |
1da177e4 | 917 | |
973c9f4f DH |
918 | /** |
919 | * key_link - Link a key to a keyring | |
920 | * @keyring: The keyring to make the link in. | |
921 | * @key: The key to link to. | |
922 | * | |
923 | * Make a link in a keyring to a key, such that the keyring holds a reference | |
924 | * on that key and the key can potentially be found by searching that keyring. | |
925 | * | |
926 | * This function will write-lock the keyring's semaphore and will consume some | |
927 | * of the user's key data quota to hold the link. | |
928 | * | |
929 | * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, | |
930 | * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is | |
931 | * full, -EDQUOT if there is insufficient key data quota remaining to add | |
932 | * another link or -ENOMEM if there's insufficient memory. | |
933 | * | |
934 | * It is assumed that the caller has checked that it is permitted for a link to | |
935 | * be made (the keyring should have Write permission and the key Link | |
936 | * permission). | |
1da177e4 LT |
937 | */ |
938 | int key_link(struct key *keyring, struct key *key) | |
939 | { | |
ceb73c12 | 940 | unsigned long prealloc; |
1da177e4 LT |
941 | int ret; |
942 | ||
943 | key_check(keyring); | |
944 | key_check(key); | |
945 | ||
f70e2e06 DH |
946 | ret = __key_link_begin(keyring, key->type, key->description, &prealloc); |
947 | if (ret == 0) { | |
948 | ret = __key_link_check_live_key(keyring, key); | |
949 | if (ret == 0) | |
950 | __key_link(keyring, key, &prealloc); | |
951 | __key_link_end(keyring, key->type, prealloc); | |
952 | } | |
1da177e4 LT |
953 | |
954 | return ret; | |
f70e2e06 | 955 | } |
1da177e4 LT |
956 | EXPORT_SYMBOL(key_link); |
957 | ||
973c9f4f DH |
958 | /** |
959 | * key_unlink - Unlink the first link to a key from a keyring. | |
960 | * @keyring: The keyring to remove the link from. | |
961 | * @key: The key the link is to. | |
962 | * | |
963 | * Remove a link from a keyring to a key. | |
964 | * | |
965 | * This function will write-lock the keyring's semaphore. | |
966 | * | |
967 | * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if | |
968 | * the key isn't linked to by the keyring or -ENOMEM if there's insufficient | |
969 | * memory. | |
970 | * | |
971 | * It is assumed that the caller has checked that it is permitted for a link to | |
972 | * be removed (the keyring should have Write permission; no permissions are | |
973 | * required on the key). | |
1da177e4 LT |
974 | */ |
975 | int key_unlink(struct key *keyring, struct key *key) | |
976 | { | |
76d8aeab | 977 | struct keyring_list *klist, *nklist; |
1da177e4 LT |
978 | int loop, ret; |
979 | ||
980 | key_check(keyring); | |
981 | key_check(key); | |
982 | ||
983 | ret = -ENOTDIR; | |
984 | if (keyring->type != &key_type_keyring) | |
985 | goto error; | |
986 | ||
987 | down_write(&keyring->sem); | |
988 | ||
f0641cba | 989 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
990 | if (klist) { |
991 | /* search the keyring for the key */ | |
992 | for (loop = 0; loop < klist->nkeys; loop++) | |
993 | if (klist->keys[loop] == key) | |
994 | goto key_is_present; | |
995 | } | |
996 | ||
997 | up_write(&keyring->sem); | |
998 | ret = -ENOENT; | |
999 | goto error; | |
1000 | ||
76d8aeab DH |
1001 | key_is_present: |
1002 | /* we need to copy the key list for RCU purposes */ | |
a4014d8f DH |
1003 | nklist = kmalloc(sizeof(*klist) + |
1004 | sizeof(struct key *) * klist->maxkeys, | |
76d8aeab DH |
1005 | GFP_KERNEL); |
1006 | if (!nklist) | |
1007 | goto nomem; | |
1008 | nklist->maxkeys = klist->maxkeys; | |
1009 | nklist->nkeys = klist->nkeys - 1; | |
1010 | ||
1011 | if (loop > 0) | |
1012 | memcpy(&nklist->keys[0], | |
1013 | &klist->keys[0], | |
a4014d8f | 1014 | loop * sizeof(struct key *)); |
76d8aeab DH |
1015 | |
1016 | if (loop < nklist->nkeys) | |
1017 | memcpy(&nklist->keys[loop], | |
1018 | &klist->keys[loop + 1], | |
a4014d8f | 1019 | (nklist->nkeys - loop) * sizeof(struct key *)); |
76d8aeab | 1020 | |
1da177e4 LT |
1021 | /* adjust the user's quota */ |
1022 | key_payload_reserve(keyring, | |
1023 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
1024 | ||
76d8aeab | 1025 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
1da177e4 | 1026 | |
76d8aeab | 1027 | up_write(&keyring->sem); |
1da177e4 | 1028 | |
76d8aeab DH |
1029 | /* schedule for later cleanup */ |
1030 | klist->delkey = loop; | |
1031 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
1da177e4 | 1032 | |
1da177e4 LT |
1033 | ret = 0; |
1034 | ||
76d8aeab | 1035 | error: |
1da177e4 | 1036 | return ret; |
76d8aeab DH |
1037 | nomem: |
1038 | ret = -ENOMEM; | |
1039 | up_write(&keyring->sem); | |
1040 | goto error; | |
a8b17ed0 | 1041 | } |
1da177e4 LT |
1042 | EXPORT_SYMBOL(key_unlink); |
1043 | ||
76d8aeab | 1044 | /* |
973c9f4f DH |
1045 | * Dispose of a keyring list after the RCU grace period, releasing the keys it |
1046 | * links to. | |
76d8aeab DH |
1047 | */ |
1048 | static void keyring_clear_rcu_disposal(struct rcu_head *rcu) | |
1049 | { | |
1050 | struct keyring_list *klist; | |
1051 | int loop; | |
1052 | ||
1053 | klist = container_of(rcu, struct keyring_list, rcu); | |
1054 | ||
1055 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
1056 | key_put(klist->keys[loop]); | |
1057 | ||
1058 | kfree(klist); | |
a8b17ed0 | 1059 | } |
76d8aeab | 1060 | |
973c9f4f DH |
1061 | /** |
1062 | * keyring_clear - Clear a keyring | |
1063 | * @keyring: The keyring to clear. | |
1064 | * | |
1065 | * Clear the contents of the specified keyring. | |
1066 | * | |
1067 | * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring. | |
1da177e4 LT |
1068 | */ |
1069 | int keyring_clear(struct key *keyring) | |
1070 | { | |
1071 | struct keyring_list *klist; | |
76d8aeab | 1072 | int ret; |
1da177e4 LT |
1073 | |
1074 | ret = -ENOTDIR; | |
1075 | if (keyring->type == &key_type_keyring) { | |
1076 | /* detach the pointer block with the locks held */ | |
1077 | down_write(&keyring->sem); | |
1078 | ||
f0641cba | 1079 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
1080 | if (klist) { |
1081 | /* adjust the quota */ | |
1082 | key_payload_reserve(keyring, | |
1083 | sizeof(struct keyring_list)); | |
1084 | ||
76d8aeab DH |
1085 | rcu_assign_pointer(keyring->payload.subscriptions, |
1086 | NULL); | |
1da177e4 LT |
1087 | } |
1088 | ||
1089 | up_write(&keyring->sem); | |
1090 | ||
1091 | /* free the keys after the locks have been dropped */ | |
76d8aeab DH |
1092 | if (klist) |
1093 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1da177e4 LT |
1094 | |
1095 | ret = 0; | |
1096 | } | |
1097 | ||
1098 | return ret; | |
a8b17ed0 | 1099 | } |
1da177e4 | 1100 | EXPORT_SYMBOL(keyring_clear); |
31204ed9 | 1101 | |
31204ed9 | 1102 | /* |
973c9f4f DH |
1103 | * Dispose of the links from a revoked keyring. |
1104 | * | |
1105 | * This is called with the key sem write-locked. | |
31204ed9 DH |
1106 | */ |
1107 | static void keyring_revoke(struct key *keyring) | |
1108 | { | |
f0641cba DH |
1109 | struct keyring_list *klist; |
1110 | ||
1111 | klist = rcu_dereference_locked_keyring(keyring); | |
31204ed9 DH |
1112 | |
1113 | /* adjust the quota */ | |
1114 | key_payload_reserve(keyring, 0); | |
1115 | ||
1116 | if (klist) { | |
1117 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1118 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1119 | } | |
a8b17ed0 | 1120 | } |
5d135440 DH |
1121 | |
1122 | /* | |
973c9f4f | 1123 | * Determine whether a key is dead. |
5d135440 DH |
1124 | */ |
1125 | static bool key_is_dead(struct key *key, time_t limit) | |
1126 | { | |
1127 | return test_bit(KEY_FLAG_DEAD, &key->flags) || | |
1128 | (key->expiry > 0 && key->expiry <= limit); | |
1129 | } | |
1130 | ||
1131 | /* | |
973c9f4f DH |
1132 | * Collect garbage from the contents of a keyring, replacing the old list with |
1133 | * a new one with the pointers all shuffled down. | |
1134 | * | |
1135 | * Dead keys are classed as oned that are flagged as being dead or are revoked, | |
1136 | * expired or negative keys that were revoked or expired before the specified | |
1137 | * limit. | |
5d135440 DH |
1138 | */ |
1139 | void keyring_gc(struct key *keyring, time_t limit) | |
1140 | { | |
1141 | struct keyring_list *klist, *new; | |
1142 | struct key *key; | |
1143 | int loop, keep, max; | |
1144 | ||
c08ef808 | 1145 | kenter("{%x,%s}", key_serial(keyring), keyring->description); |
5d135440 DH |
1146 | |
1147 | down_write(&keyring->sem); | |
1148 | ||
f0641cba | 1149 | klist = rcu_dereference_locked_keyring(keyring); |
5d135440 | 1150 | if (!klist) |
c08ef808 | 1151 | goto no_klist; |
5d135440 DH |
1152 | |
1153 | /* work out how many subscriptions we're keeping */ | |
1154 | keep = 0; | |
1155 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
c08ef808 | 1156 | if (!key_is_dead(klist->keys[loop], limit)) |
5d135440 DH |
1157 | keep++; |
1158 | ||
1159 | if (keep == klist->nkeys) | |
1160 | goto just_return; | |
1161 | ||
1162 | /* allocate a new keyring payload */ | |
1163 | max = roundup(keep, 4); | |
1164 | new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *), | |
1165 | GFP_KERNEL); | |
1166 | if (!new) | |
c08ef808 | 1167 | goto nomem; |
5d135440 DH |
1168 | new->maxkeys = max; |
1169 | new->nkeys = 0; | |
1170 | new->delkey = 0; | |
1171 | ||
1172 | /* install the live keys | |
1173 | * - must take care as expired keys may be updated back to life | |
1174 | */ | |
1175 | keep = 0; | |
1176 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { | |
1177 | key = klist->keys[loop]; | |
1178 | if (!key_is_dead(key, limit)) { | |
1179 | if (keep >= max) | |
1180 | goto discard_new; | |
1181 | new->keys[keep++] = key_get(key); | |
1182 | } | |
1183 | } | |
1184 | new->nkeys = keep; | |
1185 | ||
1186 | /* adjust the quota */ | |
1187 | key_payload_reserve(keyring, | |
1188 | sizeof(struct keyring_list) + | |
1189 | KEYQUOTA_LINK_BYTES * keep); | |
1190 | ||
1191 | if (keep == 0) { | |
1192 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1193 | kfree(new); | |
1194 | } else { | |
1195 | rcu_assign_pointer(keyring->payload.subscriptions, new); | |
1196 | } | |
1197 | ||
1198 | up_write(&keyring->sem); | |
1199 | ||
1200 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1201 | kleave(" [yes]"); | |
1202 | return; | |
1203 | ||
1204 | discard_new: | |
1205 | new->nkeys = keep; | |
1206 | keyring_clear_rcu_disposal(&new->rcu); | |
c08ef808 DH |
1207 | up_write(&keyring->sem); |
1208 | kleave(" [discard]"); | |
1209 | return; | |
1210 | ||
5d135440 DH |
1211 | just_return: |
1212 | up_write(&keyring->sem); | |
c08ef808 DH |
1213 | kleave(" [no dead]"); |
1214 | return; | |
1215 | ||
1216 | no_klist: | |
1217 | up_write(&keyring->sem); | |
1218 | kleave(" [no_klist]"); | |
1219 | return; | |
1220 | ||
1221 | nomem: | |
1222 | up_write(&keyring->sem); | |
1223 | kleave(" [oom]"); | |
5d135440 | 1224 | } |