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 | ||
233e4735 DH |
28 | #define rcu_deref_link_locked(klist, index, keyring) \ |
29 | (rcu_dereference_protected( \ | |
30 | (klist)->keys[index], \ | |
31 | rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem))) | |
32 | ||
31d5a79d DH |
33 | #define MAX_KEYRING_LINKS \ |
34 | min_t(size_t, USHRT_MAX - 1, \ | |
35 | ((PAGE_SIZE - sizeof(struct keyring_list)) / sizeof(struct key *))) | |
36 | ||
ceb73c12 DH |
37 | #define KEY_LINK_FIXQUOTA 1UL |
38 | ||
1da177e4 | 39 | /* |
973c9f4f DH |
40 | * When plumbing the depths of the key tree, this sets a hard limit |
41 | * set on how deep we're willing to go. | |
1da177e4 LT |
42 | */ |
43 | #define KEYRING_SEARCH_MAX_DEPTH 6 | |
44 | ||
45 | /* | |
973c9f4f | 46 | * We keep all named keyrings in a hash to speed looking them up. |
1da177e4 LT |
47 | */ |
48 | #define KEYRING_NAME_HASH_SIZE (1 << 5) | |
49 | ||
50 | static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE]; | |
51 | static DEFINE_RWLOCK(keyring_name_lock); | |
52 | ||
53 | static inline unsigned keyring_hash(const char *desc) | |
54 | { | |
55 | unsigned bucket = 0; | |
56 | ||
57 | for (; *desc; desc++) | |
c5b60b5e | 58 | bucket += (unsigned char)*desc; |
1da177e4 LT |
59 | |
60 | return bucket & (KEYRING_NAME_HASH_SIZE - 1); | |
61 | } | |
62 | ||
63 | /* | |
973c9f4f DH |
64 | * The keyring key type definition. Keyrings are simply keys of this type and |
65 | * can be treated as ordinary keys in addition to having their own special | |
66 | * operations. | |
1da177e4 LT |
67 | */ |
68 | static int keyring_instantiate(struct key *keyring, | |
cf7f601c | 69 | struct key_preparsed_payload *prep); |
1da177e4 | 70 | static int keyring_match(const struct key *keyring, const void *criterion); |
31204ed9 | 71 | static void keyring_revoke(struct key *keyring); |
1da177e4 LT |
72 | static void keyring_destroy(struct key *keyring); |
73 | static void keyring_describe(const struct key *keyring, struct seq_file *m); | |
74 | static long keyring_read(const struct key *keyring, | |
75 | char __user *buffer, size_t buflen); | |
76 | ||
77 | struct key_type key_type_keyring = { | |
78 | .name = "keyring", | |
79 | .def_datalen = sizeof(struct keyring_list), | |
80 | .instantiate = keyring_instantiate, | |
1da177e4 | 81 | .match = keyring_match, |
31204ed9 | 82 | .revoke = keyring_revoke, |
1da177e4 LT |
83 | .destroy = keyring_destroy, |
84 | .describe = keyring_describe, | |
85 | .read = keyring_read, | |
86 | }; | |
7318226e DH |
87 | EXPORT_SYMBOL(key_type_keyring); |
88 | ||
1da177e4 | 89 | /* |
973c9f4f DH |
90 | * Semaphore to serialise link/link calls to prevent two link calls in parallel |
91 | * introducing a cycle. | |
1da177e4 | 92 | */ |
1ae8f407 | 93 | static DECLARE_RWSEM(keyring_serialise_link_sem); |
1da177e4 | 94 | |
1da177e4 | 95 | /* |
973c9f4f DH |
96 | * Publish the name of a keyring so that it can be found by name (if it has |
97 | * one). | |
1da177e4 | 98 | */ |
69664cf1 | 99 | static void keyring_publish_name(struct key *keyring) |
1da177e4 LT |
100 | { |
101 | int bucket; | |
102 | ||
103 | if (keyring->description) { | |
104 | bucket = keyring_hash(keyring->description); | |
105 | ||
106 | write_lock(&keyring_name_lock); | |
107 | ||
108 | if (!keyring_name_hash[bucket].next) | |
109 | INIT_LIST_HEAD(&keyring_name_hash[bucket]); | |
110 | ||
111 | list_add_tail(&keyring->type_data.link, | |
112 | &keyring_name_hash[bucket]); | |
113 | ||
114 | write_unlock(&keyring_name_lock); | |
115 | } | |
a8b17ed0 | 116 | } |
1da177e4 | 117 | |
1da177e4 | 118 | /* |
973c9f4f DH |
119 | * Initialise a keyring. |
120 | * | |
121 | * Returns 0 on success, -EINVAL if given any data. | |
1da177e4 LT |
122 | */ |
123 | static int keyring_instantiate(struct key *keyring, | |
cf7f601c | 124 | struct key_preparsed_payload *prep) |
1da177e4 LT |
125 | { |
126 | int ret; | |
127 | ||
128 | ret = -EINVAL; | |
cf7f601c | 129 | if (prep->datalen == 0) { |
1da177e4 LT |
130 | /* make the keyring available by name if it has one */ |
131 | keyring_publish_name(keyring); | |
132 | ret = 0; | |
133 | } | |
134 | ||
135 | return ret; | |
a8b17ed0 | 136 | } |
1da177e4 | 137 | |
1da177e4 | 138 | /* |
973c9f4f | 139 | * Match keyrings on their name |
1da177e4 LT |
140 | */ |
141 | static int keyring_match(const struct key *keyring, const void *description) | |
142 | { | |
143 | return keyring->description && | |
144 | strcmp(keyring->description, description) == 0; | |
a8b17ed0 | 145 | } |
1da177e4 | 146 | |
1da177e4 | 147 | /* |
973c9f4f DH |
148 | * Clean up a keyring when it is destroyed. Unpublish its name if it had one |
149 | * and dispose of its data. | |
233e4735 DH |
150 | * |
151 | * The garbage collector detects the final key_put(), removes the keyring from | |
152 | * the serial number tree and then does RCU synchronisation before coming here, | |
153 | * so we shouldn't need to worry about code poking around here with the RCU | |
154 | * readlock held by this time. | |
1da177e4 LT |
155 | */ |
156 | static void keyring_destroy(struct key *keyring) | |
157 | { | |
158 | struct keyring_list *klist; | |
159 | int loop; | |
160 | ||
161 | if (keyring->description) { | |
162 | write_lock(&keyring_name_lock); | |
94efe72f DH |
163 | |
164 | if (keyring->type_data.link.next != NULL && | |
165 | !list_empty(&keyring->type_data.link)) | |
166 | list_del(&keyring->type_data.link); | |
167 | ||
1da177e4 LT |
168 | write_unlock(&keyring_name_lock); |
169 | } | |
170 | ||
233e4735 | 171 | klist = rcu_access_pointer(keyring->payload.subscriptions); |
1da177e4 LT |
172 | if (klist) { |
173 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
233e4735 | 174 | key_put(rcu_access_pointer(klist->keys[loop])); |
1da177e4 LT |
175 | kfree(klist); |
176 | } | |
a8b17ed0 | 177 | } |
1da177e4 | 178 | |
1da177e4 | 179 | /* |
973c9f4f | 180 | * Describe a keyring for /proc. |
1da177e4 LT |
181 | */ |
182 | static void keyring_describe(const struct key *keyring, struct seq_file *m) | |
183 | { | |
184 | struct keyring_list *klist; | |
185 | ||
c8563473 | 186 | if (keyring->description) |
1da177e4 | 187 | seq_puts(m, keyring->description); |
c8563473 | 188 | else |
1da177e4 | 189 | seq_puts(m, "[anon]"); |
1da177e4 | 190 | |
78b7280c DH |
191 | if (key_is_instantiated(keyring)) { |
192 | rcu_read_lock(); | |
193 | klist = rcu_dereference(keyring->payload.subscriptions); | |
194 | if (klist) | |
195 | seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys); | |
196 | else | |
197 | seq_puts(m, ": empty"); | |
198 | rcu_read_unlock(); | |
199 | } | |
a8b17ed0 | 200 | } |
1da177e4 | 201 | |
1da177e4 | 202 | /* |
973c9f4f DH |
203 | * Read a list of key IDs from the keyring's contents in binary form |
204 | * | |
205 | * The keyring's semaphore is read-locked by the caller. | |
1da177e4 LT |
206 | */ |
207 | static long keyring_read(const struct key *keyring, | |
208 | char __user *buffer, size_t buflen) | |
209 | { | |
210 | struct keyring_list *klist; | |
211 | struct key *key; | |
212 | size_t qty, tmp; | |
213 | int loop, ret; | |
214 | ||
215 | ret = 0; | |
f0641cba | 216 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
217 | if (klist) { |
218 | /* calculate how much data we could return */ | |
219 | qty = klist->nkeys * sizeof(key_serial_t); | |
220 | ||
221 | if (buffer && buflen > 0) { | |
222 | if (buflen > qty) | |
223 | buflen = qty; | |
224 | ||
225 | /* copy the IDs of the subscribed keys into the | |
226 | * buffer */ | |
227 | ret = -EFAULT; | |
228 | ||
229 | for (loop = 0; loop < klist->nkeys; loop++) { | |
233e4735 DH |
230 | key = rcu_deref_link_locked(klist, loop, |
231 | keyring); | |
1da177e4 LT |
232 | |
233 | tmp = sizeof(key_serial_t); | |
234 | if (tmp > buflen) | |
235 | tmp = buflen; | |
236 | ||
237 | if (copy_to_user(buffer, | |
238 | &key->serial, | |
239 | tmp) != 0) | |
240 | goto error; | |
241 | ||
242 | buflen -= tmp; | |
243 | if (buflen == 0) | |
244 | break; | |
245 | buffer += tmp; | |
246 | } | |
247 | } | |
248 | ||
249 | ret = qty; | |
250 | } | |
251 | ||
c5b60b5e | 252 | error: |
1da177e4 | 253 | return ret; |
a8b17ed0 | 254 | } |
1da177e4 | 255 | |
1da177e4 | 256 | /* |
973c9f4f | 257 | * Allocate a keyring and link into the destination keyring. |
1da177e4 | 258 | */ |
9a56c2db | 259 | struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, |
96b5c8fe DH |
260 | const struct cred *cred, key_perm_t perm, |
261 | unsigned long flags, struct key *dest) | |
1da177e4 LT |
262 | { |
263 | struct key *keyring; | |
264 | int ret; | |
265 | ||
266 | keyring = key_alloc(&key_type_keyring, description, | |
96b5c8fe | 267 | uid, gid, cred, perm, flags); |
1da177e4 | 268 | if (!IS_ERR(keyring)) { |
3e30148c | 269 | ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); |
1da177e4 LT |
270 | if (ret < 0) { |
271 | key_put(keyring); | |
272 | keyring = ERR_PTR(ret); | |
273 | } | |
274 | } | |
275 | ||
276 | return keyring; | |
a8b17ed0 | 277 | } |
f8aa23a5 | 278 | EXPORT_SYMBOL(keyring_alloc); |
1da177e4 | 279 | |
973c9f4f DH |
280 | /** |
281 | * keyring_search_aux - Search a keyring tree for a key matching some criteria | |
282 | * @keyring_ref: A pointer to the keyring with possession indicator. | |
283 | * @cred: The credentials to use for permissions checks. | |
284 | * @type: The type of key to search for. | |
285 | * @description: Parameter for @match. | |
286 | * @match: Function to rule on whether or not a key is the one required. | |
78b7280c | 287 | * @no_state_check: Don't check if a matching key is bad |
973c9f4f DH |
288 | * |
289 | * Search the supplied keyring tree for a key that matches the criteria given. | |
290 | * The root keyring and any linked keyrings must grant Search permission to the | |
291 | * caller to be searchable and keys can only be found if they too grant Search | |
292 | * to the caller. The possession flag on the root keyring pointer controls use | |
293 | * of the possessor bits in permissions checking of the entire tree. In | |
294 | * addition, the LSM gets to forbid keyring searches and key matches. | |
295 | * | |
296 | * The search is performed as a breadth-then-depth search up to the prescribed | |
297 | * limit (KEYRING_SEARCH_MAX_DEPTH). | |
298 | * | |
299 | * Keys are matched to the type provided and are then filtered by the match | |
300 | * function, which is given the description to use in any way it sees fit. The | |
301 | * match function may use any attributes of a key that it wishes to to | |
302 | * determine the match. Normally the match function from the key type would be | |
303 | * used. | |
304 | * | |
305 | * RCU is used to prevent the keyring key lists from disappearing without the | |
306 | * need to take lots of locks. | |
307 | * | |
308 | * Returns a pointer to the found key and increments the key usage count if | |
309 | * successful; -EAGAIN if no matching keys were found, or if expired or revoked | |
310 | * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the | |
311 | * specified keyring wasn't a keyring. | |
312 | * | |
313 | * In the case of a successful return, the possession attribute from | |
314 | * @keyring_ref is propagated to the returned key reference. | |
1da177e4 | 315 | */ |
664cceb0 | 316 | key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
d84f4f99 | 317 | const struct cred *cred, |
664cceb0 DH |
318 | struct key_type *type, |
319 | const void *description, | |
78b7280c DH |
320 | key_match_func_t match, |
321 | bool no_state_check) | |
1da177e4 LT |
322 | { |
323 | struct { | |
31d5a79d DH |
324 | /* Need a separate keylist pointer for RCU purposes */ |
325 | struct key *keyring; | |
76d8aeab | 326 | struct keyring_list *keylist; |
1da177e4 LT |
327 | int kix; |
328 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
329 | ||
330 | struct keyring_list *keylist; | |
331 | struct timespec now; | |
a5b4bd28 | 332 | unsigned long kflags; |
664cceb0 DH |
333 | struct key *keyring, *key; |
334 | key_ref_t key_ref; | |
a5b4bd28 | 335 | bool possessed; |
1da177e4 | 336 | long err; |
efde8b6e | 337 | int sp, nkeys, kix; |
1da177e4 | 338 | |
664cceb0 DH |
339 | keyring = key_ref_to_ptr(keyring_ref); |
340 | possessed = is_key_possessed(keyring_ref); | |
1da177e4 LT |
341 | key_check(keyring); |
342 | ||
343 | /* top keyring must have search permission to begin the search */ | |
512ea3bc | 344 | err = key_task_permission(keyring_ref, cred, KEY_SEARCH); |
29db9190 DH |
345 | if (err < 0) { |
346 | key_ref = ERR_PTR(err); | |
1da177e4 | 347 | goto error; |
29db9190 | 348 | } |
1da177e4 | 349 | |
664cceb0 | 350 | key_ref = ERR_PTR(-ENOTDIR); |
1da177e4 LT |
351 | if (keyring->type != &key_type_keyring) |
352 | goto error; | |
353 | ||
664cceb0 DH |
354 | rcu_read_lock(); |
355 | ||
1da177e4 LT |
356 | now = current_kernel_time(); |
357 | err = -EAGAIN; | |
358 | sp = 0; | |
359 | ||
dceba994 KC |
360 | /* firstly we should check to see if this top-level keyring is what we |
361 | * are looking for */ | |
362 | key_ref = ERR_PTR(-EAGAIN); | |
363 | kflags = keyring->flags; | |
364 | if (keyring->type == type && match(keyring, description)) { | |
365 | key = keyring; | |
78b7280c DH |
366 | if (no_state_check) |
367 | goto found; | |
dceba994 KC |
368 | |
369 | /* check it isn't negative and hasn't expired or been | |
370 | * revoked */ | |
371 | if (kflags & (1 << KEY_FLAG_REVOKED)) | |
372 | goto error_2; | |
373 | if (key->expiry && now.tv_sec >= key->expiry) | |
374 | goto error_2; | |
fdd1b945 | 375 | key_ref = ERR_PTR(key->type_data.reject_error); |
dceba994 KC |
376 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) |
377 | goto error_2; | |
378 | goto found; | |
379 | } | |
380 | ||
381 | /* otherwise, the top keyring must not be revoked, expired, or | |
382 | * negatively instantiated if we are to search it */ | |
383 | key_ref = ERR_PTR(-EAGAIN); | |
fd75815f DH |
384 | if (kflags & ((1 << KEY_FLAG_INVALIDATED) | |
385 | (1 << KEY_FLAG_REVOKED) | | |
386 | (1 << KEY_FLAG_NEGATIVE)) || | |
dceba994 KC |
387 | (keyring->expiry && now.tv_sec >= keyring->expiry)) |
388 | goto error_2; | |
389 | ||
1da177e4 | 390 | /* start processing a new keyring */ |
664cceb0 | 391 | descend: |
fd75815f DH |
392 | kflags = keyring->flags; |
393 | if (kflags & ((1 << KEY_FLAG_INVALIDATED) | | |
394 | (1 << KEY_FLAG_REVOKED))) | |
1da177e4 LT |
395 | goto not_this_keyring; |
396 | ||
76d8aeab | 397 | keylist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
398 | if (!keylist) |
399 | goto not_this_keyring; | |
400 | ||
401 | /* iterate through the keys in this keyring first */ | |
efde8b6e DH |
402 | nkeys = keylist->nkeys; |
403 | smp_rmb(); | |
404 | for (kix = 0; kix < nkeys; kix++) { | |
233e4735 | 405 | key = rcu_dereference(keylist->keys[kix]); |
dceba994 | 406 | kflags = key->flags; |
1da177e4 LT |
407 | |
408 | /* ignore keys not of this type */ | |
409 | if (key->type != type) | |
410 | continue; | |
411 | ||
fd75815f | 412 | /* skip invalidated, revoked and expired keys */ |
78b7280c | 413 | if (!no_state_check) { |
fd75815f DH |
414 | if (kflags & ((1 << KEY_FLAG_INVALIDATED) | |
415 | (1 << KEY_FLAG_REVOKED))) | |
78b7280c | 416 | continue; |
1da177e4 | 417 | |
78b7280c DH |
418 | if (key->expiry && now.tv_sec >= key->expiry) |
419 | continue; | |
420 | } | |
1da177e4 LT |
421 | |
422 | /* keys that don't match */ | |
423 | if (!match(key, description)) | |
424 | continue; | |
425 | ||
426 | /* key must have search permissions */ | |
29db9190 | 427 | if (key_task_permission(make_key_ref(key, possessed), |
d84f4f99 | 428 | cred, KEY_SEARCH) < 0) |
1da177e4 LT |
429 | continue; |
430 | ||
78b7280c DH |
431 | if (no_state_check) |
432 | goto found; | |
433 | ||
dceba994 KC |
434 | /* we set a different error code if we pass a negative key */ |
435 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) { | |
fdd1b945 | 436 | err = key->type_data.reject_error; |
1da177e4 LT |
437 | continue; |
438 | } | |
439 | ||
440 | goto found; | |
441 | } | |
442 | ||
443 | /* search through the keyrings nested in this one */ | |
444 | kix = 0; | |
664cceb0 | 445 | ascend: |
efde8b6e DH |
446 | nkeys = keylist->nkeys; |
447 | smp_rmb(); | |
448 | for (; kix < nkeys; kix++) { | |
233e4735 | 449 | key = rcu_dereference(keylist->keys[kix]); |
1da177e4 | 450 | if (key->type != &key_type_keyring) |
76d8aeab | 451 | continue; |
1da177e4 LT |
452 | |
453 | /* recursively search nested keyrings | |
454 | * - only search keyrings for which we have search permission | |
455 | */ | |
456 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
76d8aeab | 457 | continue; |
1da177e4 | 458 | |
0f6ed7c2 | 459 | if (key_task_permission(make_key_ref(key, possessed), |
d84f4f99 | 460 | cred, KEY_SEARCH) < 0) |
76d8aeab | 461 | continue; |
1da177e4 LT |
462 | |
463 | /* stack the current position */ | |
31d5a79d | 464 | stack[sp].keyring = keyring; |
76d8aeab | 465 | stack[sp].keylist = keylist; |
1da177e4 LT |
466 | stack[sp].kix = kix; |
467 | sp++; | |
468 | ||
469 | /* begin again with the new keyring */ | |
470 | keyring = key; | |
471 | goto descend; | |
1da177e4 LT |
472 | } |
473 | ||
474 | /* the keyring we're looking at was disqualified or didn't contain a | |
475 | * matching key */ | |
664cceb0 | 476 | not_this_keyring: |
1da177e4 LT |
477 | if (sp > 0) { |
478 | /* resume the processing of a keyring higher up in the tree */ | |
479 | sp--; | |
31d5a79d | 480 | keyring = stack[sp].keyring; |
76d8aeab | 481 | keylist = stack[sp].keylist; |
1da177e4 LT |
482 | kix = stack[sp].kix + 1; |
483 | goto ascend; | |
484 | } | |
485 | ||
664cceb0 DH |
486 | key_ref = ERR_PTR(err); |
487 | goto error_2; | |
1da177e4 LT |
488 | |
489 | /* we found a viable match */ | |
664cceb0 | 490 | found: |
1da177e4 | 491 | atomic_inc(&key->usage); |
31d5a79d DH |
492 | key->last_used_at = now.tv_sec; |
493 | keyring->last_used_at = now.tv_sec; | |
494 | while (sp > 0) | |
495 | stack[--sp].keyring->last_used_at = now.tv_sec; | |
1da177e4 | 496 | key_check(key); |
664cceb0 DH |
497 | key_ref = make_key_ref(key, possessed); |
498 | error_2: | |
76d8aeab | 499 | rcu_read_unlock(); |
664cceb0 DH |
500 | error: |
501 | return key_ref; | |
a8b17ed0 | 502 | } |
1da177e4 | 503 | |
973c9f4f DH |
504 | /** |
505 | * keyring_search - Search the supplied keyring tree for a matching key | |
506 | * @keyring: The root of the keyring tree to be searched. | |
507 | * @type: The type of keyring we want to find. | |
508 | * @description: The name of the keyring we want to find. | |
509 | * | |
510 | * As keyring_search_aux() above, but using the current task's credentials and | |
511 | * type's default matching function. | |
1da177e4 | 512 | */ |
664cceb0 DH |
513 | key_ref_t keyring_search(key_ref_t keyring, |
514 | struct key_type *type, | |
515 | const char *description) | |
1da177e4 | 516 | { |
3e30148c DH |
517 | if (!type->match) |
518 | return ERR_PTR(-ENOKEY); | |
519 | ||
d84f4f99 | 520 | return keyring_search_aux(keyring, current->cred, |
78b7280c | 521 | type, description, type->match, false); |
a8b17ed0 | 522 | } |
1da177e4 LT |
523 | EXPORT_SYMBOL(keyring_search); |
524 | ||
1da177e4 | 525 | /* |
973c9f4f DH |
526 | * Search the given keyring only (no recursion). |
527 | * | |
528 | * The caller must guarantee that the keyring is a keyring and that the | |
529 | * permission is granted to search the keyring as no check is made here. | |
530 | * | |
531 | * RCU is used to make it unnecessary to lock the keyring key list here. | |
532 | * | |
533 | * Returns a pointer to the found key with usage count incremented if | |
534 | * successful and returns -ENOKEY if not found. Revoked keys and keys not | |
535 | * providing the requested permission are skipped over. | |
536 | * | |
537 | * If successful, the possession indicator is propagated from the keyring ref | |
538 | * to the returned key reference. | |
1da177e4 | 539 | */ |
664cceb0 | 540 | key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
16feef43 | 541 | const struct keyring_index_key *index_key, |
664cceb0 | 542 | key_perm_t perm) |
1da177e4 LT |
543 | { |
544 | struct keyring_list *klist; | |
664cceb0 | 545 | struct key *keyring, *key; |
a5b4bd28 | 546 | bool possessed; |
efde8b6e | 547 | int nkeys, loop; |
1da177e4 | 548 | |
664cceb0 DH |
549 | keyring = key_ref_to_ptr(keyring_ref); |
550 | possessed = is_key_possessed(keyring_ref); | |
551 | ||
76d8aeab DH |
552 | rcu_read_lock(); |
553 | ||
554 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 | 555 | if (klist) { |
efde8b6e DH |
556 | nkeys = klist->nkeys; |
557 | smp_rmb(); | |
558 | for (loop = 0; loop < nkeys ; loop++) { | |
233e4735 | 559 | key = rcu_dereference(klist->keys[loop]); |
16feef43 | 560 | if (key->type == index_key->type && |
3e30148c | 561 | (!key->type->match || |
16feef43 | 562 | key->type->match(key, index_key->description)) && |
664cceb0 | 563 | key_permission(make_key_ref(key, possessed), |
db1d1d57 | 564 | perm) == 0 && |
fd75815f DH |
565 | !(key->flags & ((1 << KEY_FLAG_INVALIDATED) | |
566 | (1 << KEY_FLAG_REVOKED))) | |
1da177e4 LT |
567 | ) |
568 | goto found; | |
569 | } | |
570 | } | |
571 | ||
664cceb0 DH |
572 | rcu_read_unlock(); |
573 | return ERR_PTR(-ENOKEY); | |
1da177e4 | 574 | |
c5b60b5e | 575 | found: |
1da177e4 | 576 | atomic_inc(&key->usage); |
31d5a79d DH |
577 | keyring->last_used_at = key->last_used_at = |
578 | current_kernel_time().tv_sec; | |
76d8aeab | 579 | rcu_read_unlock(); |
664cceb0 | 580 | return make_key_ref(key, possessed); |
a8b17ed0 | 581 | } |
1da177e4 | 582 | |
1da177e4 | 583 | /* |
973c9f4f DH |
584 | * Find a keyring with the specified name. |
585 | * | |
586 | * All named keyrings in the current user namespace are searched, provided they | |
587 | * grant Search permission directly to the caller (unless this check is | |
588 | * skipped). Keyrings whose usage points have reached zero or who have been | |
589 | * revoked are skipped. | |
590 | * | |
591 | * Returns a pointer to the keyring with the keyring's refcount having being | |
592 | * incremented on success. -ENOKEY is returned if a key could not be found. | |
1da177e4 | 593 | */ |
69664cf1 | 594 | struct key *find_keyring_by_name(const char *name, bool skip_perm_check) |
1da177e4 LT |
595 | { |
596 | struct key *keyring; | |
597 | int bucket; | |
598 | ||
1da177e4 | 599 | if (!name) |
cea7daa3 | 600 | return ERR_PTR(-EINVAL); |
1da177e4 LT |
601 | |
602 | bucket = keyring_hash(name); | |
603 | ||
604 | read_lock(&keyring_name_lock); | |
605 | ||
606 | if (keyring_name_hash[bucket].next) { | |
607 | /* search this hash bucket for a keyring with a matching name | |
608 | * that's readable and that hasn't been revoked */ | |
609 | list_for_each_entry(keyring, | |
610 | &keyring_name_hash[bucket], | |
611 | type_data.link | |
612 | ) { | |
9a56c2db | 613 | if (!kuid_has_mapping(current_user_ns(), keyring->user->uid)) |
2ea190d0 SH |
614 | continue; |
615 | ||
76d8aeab | 616 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
617 | continue; |
618 | ||
619 | if (strcmp(keyring->description, name) != 0) | |
620 | continue; | |
621 | ||
69664cf1 DH |
622 | if (!skip_perm_check && |
623 | key_permission(make_key_ref(keyring, 0), | |
0f6ed7c2 | 624 | KEY_SEARCH) < 0) |
1da177e4 LT |
625 | continue; |
626 | ||
cea7daa3 TO |
627 | /* we've got a match but we might end up racing with |
628 | * key_cleanup() if the keyring is currently 'dead' | |
629 | * (ie. it has a zero usage count) */ | |
630 | if (!atomic_inc_not_zero(&keyring->usage)) | |
631 | continue; | |
31d5a79d | 632 | keyring->last_used_at = current_kernel_time().tv_sec; |
cea7daa3 | 633 | goto out; |
1da177e4 LT |
634 | } |
635 | } | |
636 | ||
1da177e4 | 637 | keyring = ERR_PTR(-ENOKEY); |
cea7daa3 TO |
638 | out: |
639 | read_unlock(&keyring_name_lock); | |
1da177e4 | 640 | return keyring; |
a8b17ed0 | 641 | } |
1da177e4 | 642 | |
1da177e4 | 643 | /* |
973c9f4f DH |
644 | * See if a cycle will will be created by inserting acyclic tree B in acyclic |
645 | * tree A at the topmost level (ie: as a direct child of A). | |
646 | * | |
647 | * Since we are adding B to A at the top level, checking for cycles should just | |
648 | * be a matter of seeing if node A is somewhere in tree B. | |
1da177e4 LT |
649 | */ |
650 | static int keyring_detect_cycle(struct key *A, struct key *B) | |
651 | { | |
652 | struct { | |
76d8aeab | 653 | struct keyring_list *keylist; |
1da177e4 LT |
654 | int kix; |
655 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
656 | ||
657 | struct keyring_list *keylist; | |
658 | struct key *subtree, *key; | |
efde8b6e | 659 | int sp, nkeys, kix, ret; |
1da177e4 | 660 | |
76d8aeab DH |
661 | rcu_read_lock(); |
662 | ||
1da177e4 LT |
663 | ret = -EDEADLK; |
664 | if (A == B) | |
76d8aeab | 665 | goto cycle_detected; |
1da177e4 LT |
666 | |
667 | subtree = B; | |
668 | sp = 0; | |
669 | ||
670 | /* start processing a new keyring */ | |
c5b60b5e | 671 | descend: |
76d8aeab | 672 | if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
1da177e4 LT |
673 | goto not_this_keyring; |
674 | ||
76d8aeab | 675 | keylist = rcu_dereference(subtree->payload.subscriptions); |
1da177e4 LT |
676 | if (!keylist) |
677 | goto not_this_keyring; | |
678 | kix = 0; | |
679 | ||
c5b60b5e | 680 | ascend: |
1da177e4 | 681 | /* iterate through the remaining keys in this keyring */ |
efde8b6e DH |
682 | nkeys = keylist->nkeys; |
683 | smp_rmb(); | |
684 | for (; kix < nkeys; kix++) { | |
233e4735 | 685 | key = rcu_dereference(keylist->keys[kix]); |
1da177e4 LT |
686 | |
687 | if (key == A) | |
688 | goto cycle_detected; | |
689 | ||
690 | /* recursively check nested keyrings */ | |
691 | if (key->type == &key_type_keyring) { | |
692 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
693 | goto too_deep; | |
694 | ||
695 | /* stack the current position */ | |
76d8aeab | 696 | stack[sp].keylist = keylist; |
1da177e4 LT |
697 | stack[sp].kix = kix; |
698 | sp++; | |
699 | ||
700 | /* begin again with the new keyring */ | |
701 | subtree = key; | |
702 | goto descend; | |
703 | } | |
704 | } | |
705 | ||
706 | /* the keyring we're looking at was disqualified or didn't contain a | |
707 | * matching key */ | |
c5b60b5e | 708 | not_this_keyring: |
1da177e4 LT |
709 | if (sp > 0) { |
710 | /* resume the checking of a keyring higher up in the tree */ | |
711 | sp--; | |
76d8aeab | 712 | keylist = stack[sp].keylist; |
1da177e4 LT |
713 | kix = stack[sp].kix + 1; |
714 | goto ascend; | |
715 | } | |
716 | ||
717 | ret = 0; /* no cycles detected */ | |
718 | ||
c5b60b5e | 719 | error: |
76d8aeab | 720 | rcu_read_unlock(); |
1da177e4 LT |
721 | return ret; |
722 | ||
c5b60b5e | 723 | too_deep: |
1da177e4 | 724 | ret = -ELOOP; |
76d8aeab DH |
725 | goto error; |
726 | ||
c5b60b5e | 727 | cycle_detected: |
1da177e4 | 728 | ret = -EDEADLK; |
1da177e4 | 729 | goto error; |
a8b17ed0 | 730 | } |
1da177e4 | 731 | |
cab8eb59 | 732 | /* |
973c9f4f | 733 | * Dispose of a keyring list after the RCU grace period, freeing the unlinked |
cab8eb59 DH |
734 | * key |
735 | */ | |
736 | static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) | |
737 | { | |
738 | struct keyring_list *klist = | |
739 | container_of(rcu, struct keyring_list, rcu); | |
740 | ||
4be929be | 741 | if (klist->delkey != USHRT_MAX) |
233e4735 | 742 | key_put(rcu_access_pointer(klist->keys[klist->delkey])); |
cab8eb59 | 743 | kfree(klist); |
f70e2e06 | 744 | } |
cab8eb59 | 745 | |
1da177e4 | 746 | /* |
973c9f4f | 747 | * Preallocate memory so that a key can be linked into to a keyring. |
1da177e4 | 748 | */ |
16feef43 DH |
749 | int __key_link_begin(struct key *keyring, const struct keyring_index_key *index_key, |
750 | unsigned long *_prealloc) | |
f70e2e06 | 751 | __acquires(&keyring->sem) |
423b9788 | 752 | __acquires(&keyring_serialise_link_sem) |
1da177e4 LT |
753 | { |
754 | struct keyring_list *klist, *nklist; | |
ceb73c12 | 755 | unsigned long prealloc; |
1da177e4 | 756 | unsigned max; |
31d5a79d | 757 | time_t lowest_lru; |
1da177e4 | 758 | size_t size; |
31d5a79d | 759 | int loop, lru, ret; |
1da177e4 | 760 | |
16feef43 DH |
761 | kenter("%d,%s,%s,", |
762 | key_serial(keyring), index_key->type->name, index_key->description); | |
1da177e4 | 763 | |
1da177e4 | 764 | if (keyring->type != &key_type_keyring) |
f70e2e06 DH |
765 | return -ENOTDIR; |
766 | ||
767 | down_write(&keyring->sem); | |
768 | ||
769 | ret = -EKEYREVOKED; | |
770 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) | |
771 | goto error_krsem; | |
1da177e4 | 772 | |
f70e2e06 DH |
773 | /* serialise link/link calls to prevent parallel calls causing a cycle |
774 | * when linking two keyring in opposite orders */ | |
16feef43 | 775 | if (index_key->type == &key_type_keyring) |
553d603c DH |
776 | down_write(&keyring_serialise_link_sem); |
777 | ||
f70e2e06 | 778 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 | 779 | |
cab8eb59 | 780 | /* see if there's a matching key we can displace */ |
31d5a79d | 781 | lru = -1; |
cab8eb59 | 782 | if (klist && klist->nkeys > 0) { |
31d5a79d | 783 | lowest_lru = TIME_T_MAX; |
cab8eb59 | 784 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { |
233e4735 DH |
785 | struct key *key = rcu_deref_link_locked(klist, loop, |
786 | keyring); | |
16feef43 DH |
787 | if (key->type == index_key->type && |
788 | strcmp(key->description, index_key->description) == 0) { | |
233e4735 DH |
789 | /* Found a match - we'll replace the link with |
790 | * one to the new key. We record the slot | |
791 | * position. | |
792 | */ | |
793 | klist->delkey = loop; | |
794 | prealloc = 0; | |
cab8eb59 DH |
795 | goto done; |
796 | } | |
31d5a79d DH |
797 | if (key->last_used_at < lowest_lru) { |
798 | lowest_lru = key->last_used_at; | |
799 | lru = loop; | |
800 | } | |
cab8eb59 DH |
801 | } |
802 | } | |
803 | ||
31d5a79d DH |
804 | /* If the keyring is full then do an LRU discard */ |
805 | if (klist && | |
806 | klist->nkeys == klist->maxkeys && | |
807 | klist->maxkeys >= MAX_KEYRING_LINKS) { | |
808 | kdebug("LRU discard %d\n", lru); | |
809 | klist->delkey = lru; | |
810 | prealloc = 0; | |
811 | goto done; | |
812 | } | |
813 | ||
1da177e4 LT |
814 | /* check that we aren't going to overrun the user's quota */ |
815 | ret = key_payload_reserve(keyring, | |
816 | keyring->datalen + KEYQUOTA_LINK_BYTES); | |
817 | if (ret < 0) | |
f70e2e06 | 818 | goto error_sem; |
1da177e4 | 819 | |
1da177e4 | 820 | if (klist && klist->nkeys < klist->maxkeys) { |
f70e2e06 | 821 | /* there's sufficient slack space to append directly */ |
233e4735 | 822 | klist->delkey = klist->nkeys; |
ceb73c12 | 823 | prealloc = KEY_LINK_FIXQUOTA; |
512ea3bc | 824 | } else { |
1da177e4 LT |
825 | /* grow the key list */ |
826 | max = 4; | |
31d5a79d | 827 | if (klist) { |
1da177e4 | 828 | max += klist->maxkeys; |
31d5a79d DH |
829 | if (max > MAX_KEYRING_LINKS) |
830 | max = MAX_KEYRING_LINKS; | |
831 | BUG_ON(max <= klist->maxkeys); | |
832 | } | |
1da177e4 | 833 | |
a4014d8f | 834 | size = sizeof(*klist) + sizeof(struct key *) * max; |
1da177e4 LT |
835 | |
836 | ret = -ENOMEM; | |
837 | nklist = kmalloc(size, GFP_KERNEL); | |
838 | if (!nklist) | |
f70e2e06 | 839 | goto error_quota; |
1da177e4 | 840 | |
f70e2e06 | 841 | nklist->maxkeys = max; |
1da177e4 | 842 | if (klist) { |
f70e2e06 | 843 | memcpy(nklist->keys, klist->keys, |
1da177e4 | 844 | sizeof(struct key *) * klist->nkeys); |
f70e2e06 DH |
845 | nklist->delkey = klist->nkeys; |
846 | nklist->nkeys = klist->nkeys + 1; | |
4be929be | 847 | klist->delkey = USHRT_MAX; |
f70e2e06 DH |
848 | } else { |
849 | nklist->nkeys = 1; | |
850 | nklist->delkey = 0; | |
1da177e4 LT |
851 | } |
852 | ||
853 | /* add the key into the new space */ | |
233e4735 DH |
854 | RCU_INIT_POINTER(nklist->keys[nklist->delkey], NULL); |
855 | prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA; | |
1da177e4 LT |
856 | } |
857 | ||
cab8eb59 | 858 | done: |
ceb73c12 | 859 | *_prealloc = prealloc; |
f70e2e06 DH |
860 | kleave(" = 0"); |
861 | return 0; | |
1da177e4 | 862 | |
f70e2e06 | 863 | error_quota: |
1da177e4 LT |
864 | /* undo the quota changes */ |
865 | key_payload_reserve(keyring, | |
866 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
f70e2e06 | 867 | error_sem: |
16feef43 | 868 | if (index_key->type == &key_type_keyring) |
f70e2e06 DH |
869 | up_write(&keyring_serialise_link_sem); |
870 | error_krsem: | |
871 | up_write(&keyring->sem); | |
872 | kleave(" = %d", ret); | |
873 | return ret; | |
874 | } | |
1da177e4 | 875 | |
f70e2e06 | 876 | /* |
973c9f4f DH |
877 | * Check already instantiated keys aren't going to be a problem. |
878 | * | |
879 | * The caller must have called __key_link_begin(). Don't need to call this for | |
880 | * keys that were created since __key_link_begin() was called. | |
f70e2e06 DH |
881 | */ |
882 | int __key_link_check_live_key(struct key *keyring, struct key *key) | |
883 | { | |
884 | if (key->type == &key_type_keyring) | |
885 | /* check that we aren't going to create a cycle by linking one | |
886 | * keyring to another */ | |
887 | return keyring_detect_cycle(keyring, key); | |
888 | return 0; | |
889 | } | |
890 | ||
891 | /* | |
973c9f4f DH |
892 | * Link a key into to a keyring. |
893 | * | |
894 | * Must be called with __key_link_begin() having being called. Discards any | |
895 | * already extant link to matching key if there is one, so that each keyring | |
896 | * holds at most one link to any given key of a particular type+description | |
897 | * combination. | |
f70e2e06 DH |
898 | */ |
899 | void __key_link(struct key *keyring, struct key *key, | |
ceb73c12 | 900 | unsigned long *_prealloc) |
f70e2e06 DH |
901 | { |
902 | struct keyring_list *klist, *nklist; | |
233e4735 | 903 | struct key *discard; |
f70e2e06 | 904 | |
ceb73c12 DH |
905 | nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA); |
906 | *_prealloc = 0; | |
f70e2e06 DH |
907 | |
908 | kenter("%d,%d,%p", keyring->serial, key->serial, nklist); | |
909 | ||
6d528b08 | 910 | klist = rcu_dereference_locked_keyring(keyring); |
f70e2e06 DH |
911 | |
912 | atomic_inc(&key->usage); | |
31d5a79d DH |
913 | keyring->last_used_at = key->last_used_at = |
914 | current_kernel_time().tv_sec; | |
f70e2e06 DH |
915 | |
916 | /* there's a matching key we can displace or an empty slot in a newly | |
917 | * allocated list we can fill */ | |
918 | if (nklist) { | |
233e4735 | 919 | kdebug("reissue %hu/%hu/%hu", |
f70e2e06 DH |
920 | nklist->delkey, nklist->nkeys, nklist->maxkeys); |
921 | ||
233e4735 | 922 | RCU_INIT_POINTER(nklist->keys[nklist->delkey], key); |
f70e2e06 DH |
923 | |
924 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); | |
925 | ||
926 | /* dispose of the old keyring list and, if there was one, the | |
927 | * displaced key */ | |
928 | if (klist) { | |
929 | kdebug("dispose %hu/%hu/%hu", | |
930 | klist->delkey, klist->nkeys, klist->maxkeys); | |
931 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
932 | } | |
233e4735 DH |
933 | } else if (klist->delkey < klist->nkeys) { |
934 | kdebug("replace %hu/%hu/%hu", | |
935 | klist->delkey, klist->nkeys, klist->maxkeys); | |
936 | ||
937 | discard = rcu_dereference_protected( | |
938 | klist->keys[klist->delkey], | |
939 | rwsem_is_locked(&keyring->sem)); | |
940 | rcu_assign_pointer(klist->keys[klist->delkey], key); | |
941 | /* The garbage collector will take care of RCU | |
942 | * synchronisation */ | |
943 | key_put(discard); | |
f70e2e06 DH |
944 | } else { |
945 | /* there's sufficient slack space to append directly */ | |
233e4735 DH |
946 | kdebug("append %hu/%hu/%hu", |
947 | klist->delkey, klist->nkeys, klist->maxkeys); | |
948 | ||
949 | RCU_INIT_POINTER(klist->keys[klist->delkey], key); | |
f70e2e06 DH |
950 | smp_wmb(); |
951 | klist->nkeys++; | |
952 | } | |
953 | } | |
954 | ||
955 | /* | |
973c9f4f DH |
956 | * Finish linking a key into to a keyring. |
957 | * | |
958 | * Must be called with __key_link_begin() having being called. | |
f70e2e06 | 959 | */ |
16feef43 DH |
960 | void __key_link_end(struct key *keyring, |
961 | const struct keyring_index_key *index_key, | |
ceb73c12 | 962 | unsigned long prealloc) |
f70e2e06 | 963 | __releases(&keyring->sem) |
423b9788 | 964 | __releases(&keyring_serialise_link_sem) |
f70e2e06 | 965 | { |
16feef43 DH |
966 | BUG_ON(index_key->type == NULL); |
967 | BUG_ON(index_key->type->name == NULL); | |
968 | kenter("%d,%s,%lx", keyring->serial, index_key->type->name, prealloc); | |
f70e2e06 | 969 | |
16feef43 | 970 | if (index_key->type == &key_type_keyring) |
f70e2e06 DH |
971 | up_write(&keyring_serialise_link_sem); |
972 | ||
973 | if (prealloc) { | |
ceb73c12 DH |
974 | if (prealloc & KEY_LINK_FIXQUOTA) |
975 | key_payload_reserve(keyring, | |
976 | keyring->datalen - | |
977 | KEYQUOTA_LINK_BYTES); | |
978 | kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA)); | |
f70e2e06 DH |
979 | } |
980 | up_write(&keyring->sem); | |
981 | } | |
1da177e4 | 982 | |
973c9f4f DH |
983 | /** |
984 | * key_link - Link a key to a keyring | |
985 | * @keyring: The keyring to make the link in. | |
986 | * @key: The key to link to. | |
987 | * | |
988 | * Make a link in a keyring to a key, such that the keyring holds a reference | |
989 | * on that key and the key can potentially be found by searching that keyring. | |
990 | * | |
991 | * This function will write-lock the keyring's semaphore and will consume some | |
992 | * of the user's key data quota to hold the link. | |
993 | * | |
994 | * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, | |
995 | * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is | |
996 | * full, -EDQUOT if there is insufficient key data quota remaining to add | |
997 | * another link or -ENOMEM if there's insufficient memory. | |
998 | * | |
999 | * It is assumed that the caller has checked that it is permitted for a link to | |
1000 | * be made (the keyring should have Write permission and the key Link | |
1001 | * permission). | |
1da177e4 LT |
1002 | */ |
1003 | int key_link(struct key *keyring, struct key *key) | |
1004 | { | |
ceb73c12 | 1005 | unsigned long prealloc; |
1da177e4 LT |
1006 | int ret; |
1007 | ||
1008 | key_check(keyring); | |
1009 | key_check(key); | |
1010 | ||
16feef43 | 1011 | ret = __key_link_begin(keyring, &key->index_key, &prealloc); |
f70e2e06 DH |
1012 | if (ret == 0) { |
1013 | ret = __key_link_check_live_key(keyring, key); | |
1014 | if (ret == 0) | |
1015 | __key_link(keyring, key, &prealloc); | |
16feef43 | 1016 | __key_link_end(keyring, &key->index_key, prealloc); |
f70e2e06 | 1017 | } |
1da177e4 LT |
1018 | |
1019 | return ret; | |
f70e2e06 | 1020 | } |
1da177e4 LT |
1021 | EXPORT_SYMBOL(key_link); |
1022 | ||
973c9f4f DH |
1023 | /** |
1024 | * key_unlink - Unlink the first link to a key from a keyring. | |
1025 | * @keyring: The keyring to remove the link from. | |
1026 | * @key: The key the link is to. | |
1027 | * | |
1028 | * Remove a link from a keyring to a key. | |
1029 | * | |
1030 | * This function will write-lock the keyring's semaphore. | |
1031 | * | |
1032 | * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if | |
1033 | * the key isn't linked to by the keyring or -ENOMEM if there's insufficient | |
1034 | * memory. | |
1035 | * | |
1036 | * It is assumed that the caller has checked that it is permitted for a link to | |
1037 | * be removed (the keyring should have Write permission; no permissions are | |
1038 | * required on the key). | |
1da177e4 LT |
1039 | */ |
1040 | int key_unlink(struct key *keyring, struct key *key) | |
1041 | { | |
76d8aeab | 1042 | struct keyring_list *klist, *nklist; |
1da177e4 LT |
1043 | int loop, ret; |
1044 | ||
1045 | key_check(keyring); | |
1046 | key_check(key); | |
1047 | ||
1048 | ret = -ENOTDIR; | |
1049 | if (keyring->type != &key_type_keyring) | |
1050 | goto error; | |
1051 | ||
1052 | down_write(&keyring->sem); | |
1053 | ||
f0641cba | 1054 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
1055 | if (klist) { |
1056 | /* search the keyring for the key */ | |
1057 | for (loop = 0; loop < klist->nkeys; loop++) | |
233e4735 | 1058 | if (rcu_access_pointer(klist->keys[loop]) == key) |
1da177e4 LT |
1059 | goto key_is_present; |
1060 | } | |
1061 | ||
1062 | up_write(&keyring->sem); | |
1063 | ret = -ENOENT; | |
1064 | goto error; | |
1065 | ||
76d8aeab DH |
1066 | key_is_present: |
1067 | /* we need to copy the key list for RCU purposes */ | |
a4014d8f DH |
1068 | nklist = kmalloc(sizeof(*klist) + |
1069 | sizeof(struct key *) * klist->maxkeys, | |
76d8aeab DH |
1070 | GFP_KERNEL); |
1071 | if (!nklist) | |
1072 | goto nomem; | |
1073 | nklist->maxkeys = klist->maxkeys; | |
1074 | nklist->nkeys = klist->nkeys - 1; | |
1075 | ||
1076 | if (loop > 0) | |
1077 | memcpy(&nklist->keys[0], | |
1078 | &klist->keys[0], | |
a4014d8f | 1079 | loop * sizeof(struct key *)); |
76d8aeab DH |
1080 | |
1081 | if (loop < nklist->nkeys) | |
1082 | memcpy(&nklist->keys[loop], | |
1083 | &klist->keys[loop + 1], | |
a4014d8f | 1084 | (nklist->nkeys - loop) * sizeof(struct key *)); |
76d8aeab | 1085 | |
1da177e4 LT |
1086 | /* adjust the user's quota */ |
1087 | key_payload_reserve(keyring, | |
1088 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
1089 | ||
76d8aeab | 1090 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
1da177e4 | 1091 | |
76d8aeab | 1092 | up_write(&keyring->sem); |
1da177e4 | 1093 | |
76d8aeab DH |
1094 | /* schedule for later cleanup */ |
1095 | klist->delkey = loop; | |
1096 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
1da177e4 | 1097 | |
1da177e4 LT |
1098 | ret = 0; |
1099 | ||
76d8aeab | 1100 | error: |
1da177e4 | 1101 | return ret; |
76d8aeab DH |
1102 | nomem: |
1103 | ret = -ENOMEM; | |
1104 | up_write(&keyring->sem); | |
1105 | goto error; | |
a8b17ed0 | 1106 | } |
1da177e4 LT |
1107 | EXPORT_SYMBOL(key_unlink); |
1108 | ||
76d8aeab | 1109 | /* |
973c9f4f DH |
1110 | * Dispose of a keyring list after the RCU grace period, releasing the keys it |
1111 | * links to. | |
76d8aeab DH |
1112 | */ |
1113 | static void keyring_clear_rcu_disposal(struct rcu_head *rcu) | |
1114 | { | |
1115 | struct keyring_list *klist; | |
1116 | int loop; | |
1117 | ||
1118 | klist = container_of(rcu, struct keyring_list, rcu); | |
1119 | ||
1120 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
233e4735 | 1121 | key_put(rcu_access_pointer(klist->keys[loop])); |
76d8aeab DH |
1122 | |
1123 | kfree(klist); | |
a8b17ed0 | 1124 | } |
76d8aeab | 1125 | |
973c9f4f DH |
1126 | /** |
1127 | * keyring_clear - Clear a keyring | |
1128 | * @keyring: The keyring to clear. | |
1129 | * | |
1130 | * Clear the contents of the specified keyring. | |
1131 | * | |
1132 | * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring. | |
1da177e4 LT |
1133 | */ |
1134 | int keyring_clear(struct key *keyring) | |
1135 | { | |
1136 | struct keyring_list *klist; | |
76d8aeab | 1137 | int ret; |
1da177e4 LT |
1138 | |
1139 | ret = -ENOTDIR; | |
1140 | if (keyring->type == &key_type_keyring) { | |
1141 | /* detach the pointer block with the locks held */ | |
1142 | down_write(&keyring->sem); | |
1143 | ||
f0641cba | 1144 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
1145 | if (klist) { |
1146 | /* adjust the quota */ | |
1147 | key_payload_reserve(keyring, | |
1148 | sizeof(struct keyring_list)); | |
1149 | ||
76d8aeab DH |
1150 | rcu_assign_pointer(keyring->payload.subscriptions, |
1151 | NULL); | |
1da177e4 LT |
1152 | } |
1153 | ||
1154 | up_write(&keyring->sem); | |
1155 | ||
1156 | /* free the keys after the locks have been dropped */ | |
76d8aeab DH |
1157 | if (klist) |
1158 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1da177e4 LT |
1159 | |
1160 | ret = 0; | |
1161 | } | |
1162 | ||
1163 | return ret; | |
a8b17ed0 | 1164 | } |
1da177e4 | 1165 | EXPORT_SYMBOL(keyring_clear); |
31204ed9 | 1166 | |
31204ed9 | 1167 | /* |
973c9f4f DH |
1168 | * Dispose of the links from a revoked keyring. |
1169 | * | |
1170 | * This is called with the key sem write-locked. | |
31204ed9 DH |
1171 | */ |
1172 | static void keyring_revoke(struct key *keyring) | |
1173 | { | |
f0641cba DH |
1174 | struct keyring_list *klist; |
1175 | ||
1176 | klist = rcu_dereference_locked_keyring(keyring); | |
31204ed9 DH |
1177 | |
1178 | /* adjust the quota */ | |
1179 | key_payload_reserve(keyring, 0); | |
1180 | ||
1181 | if (klist) { | |
1182 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1183 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1184 | } | |
a8b17ed0 | 1185 | } |
5d135440 | 1186 | |
5d135440 | 1187 | /* |
973c9f4f DH |
1188 | * Collect garbage from the contents of a keyring, replacing the old list with |
1189 | * a new one with the pointers all shuffled down. | |
1190 | * | |
1191 | * Dead keys are classed as oned that are flagged as being dead or are revoked, | |
1192 | * expired or negative keys that were revoked or expired before the specified | |
1193 | * limit. | |
5d135440 DH |
1194 | */ |
1195 | void keyring_gc(struct key *keyring, time_t limit) | |
1196 | { | |
1197 | struct keyring_list *klist, *new; | |
1198 | struct key *key; | |
1199 | int loop, keep, max; | |
1200 | ||
c08ef808 | 1201 | kenter("{%x,%s}", key_serial(keyring), keyring->description); |
5d135440 DH |
1202 | |
1203 | down_write(&keyring->sem); | |
1204 | ||
f0641cba | 1205 | klist = rcu_dereference_locked_keyring(keyring); |
5d135440 | 1206 | if (!klist) |
c08ef808 | 1207 | goto no_klist; |
5d135440 DH |
1208 | |
1209 | /* work out how many subscriptions we're keeping */ | |
1210 | keep = 0; | |
1211 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
233e4735 DH |
1212 | if (!key_is_dead(rcu_deref_link_locked(klist, loop, keyring), |
1213 | limit)) | |
5d135440 DH |
1214 | keep++; |
1215 | ||
1216 | if (keep == klist->nkeys) | |
1217 | goto just_return; | |
1218 | ||
1219 | /* allocate a new keyring payload */ | |
1220 | max = roundup(keep, 4); | |
1221 | new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *), | |
1222 | GFP_KERNEL); | |
1223 | if (!new) | |
c08ef808 | 1224 | goto nomem; |
5d135440 DH |
1225 | new->maxkeys = max; |
1226 | new->nkeys = 0; | |
1227 | new->delkey = 0; | |
1228 | ||
1229 | /* install the live keys | |
1230 | * - must take care as expired keys may be updated back to life | |
1231 | */ | |
1232 | keep = 0; | |
1233 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { | |
233e4735 | 1234 | key = rcu_deref_link_locked(klist, loop, keyring); |
5d135440 DH |
1235 | if (!key_is_dead(key, limit)) { |
1236 | if (keep >= max) | |
1237 | goto discard_new; | |
233e4735 | 1238 | RCU_INIT_POINTER(new->keys[keep++], key_get(key)); |
5d135440 DH |
1239 | } |
1240 | } | |
1241 | new->nkeys = keep; | |
1242 | ||
1243 | /* adjust the quota */ | |
1244 | key_payload_reserve(keyring, | |
1245 | sizeof(struct keyring_list) + | |
1246 | KEYQUOTA_LINK_BYTES * keep); | |
1247 | ||
1248 | if (keep == 0) { | |
1249 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1250 | kfree(new); | |
1251 | } else { | |
1252 | rcu_assign_pointer(keyring->payload.subscriptions, new); | |
1253 | } | |
1254 | ||
1255 | up_write(&keyring->sem); | |
1256 | ||
1257 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1258 | kleave(" [yes]"); | |
1259 | return; | |
1260 | ||
1261 | discard_new: | |
1262 | new->nkeys = keep; | |
1263 | keyring_clear_rcu_disposal(&new->rcu); | |
c08ef808 DH |
1264 | up_write(&keyring->sem); |
1265 | kleave(" [discard]"); | |
1266 | return; | |
1267 | ||
5d135440 DH |
1268 | just_return: |
1269 | up_write(&keyring->sem); | |
c08ef808 DH |
1270 | kleave(" [no dead]"); |
1271 | return; | |
1272 | ||
1273 | no_klist: | |
1274 | up_write(&keyring->sem); | |
1275 | kleave(" [no_klist]"); | |
1276 | return; | |
1277 | ||
1278 | nomem: | |
1279 | up_write(&keyring->sem); | |
1280 | kleave(" [oom]"); | |
5d135440 | 1281 | } |