Commit | Line | Data |
---|---|---|
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> |
1da177e4 LT |
20 | #include <asm/uaccess.h> |
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 | ||
1da177e4 LT |
28 | /* |
29 | * when plumbing the depths of the key tree, this sets a hard limit set on how | |
30 | * deep we're willing to go | |
31 | */ | |
32 | #define KEYRING_SEARCH_MAX_DEPTH 6 | |
33 | ||
34 | /* | |
35 | * we keep all named keyrings in a hash to speed looking them up | |
36 | */ | |
37 | #define KEYRING_NAME_HASH_SIZE (1 << 5) | |
38 | ||
39 | static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE]; | |
40 | static DEFINE_RWLOCK(keyring_name_lock); | |
41 | ||
42 | static inline unsigned keyring_hash(const char *desc) | |
43 | { | |
44 | unsigned bucket = 0; | |
45 | ||
46 | for (; *desc; desc++) | |
47 | bucket += (unsigned char) *desc; | |
48 | ||
49 | return bucket & (KEYRING_NAME_HASH_SIZE - 1); | |
50 | } | |
51 | ||
52 | /* | |
53 | * the keyring type definition | |
54 | */ | |
55 | static int keyring_instantiate(struct key *keyring, | |
56 | const void *data, size_t datalen); | |
1da177e4 | 57 | static int keyring_match(const struct key *keyring, const void *criterion); |
31204ed9 | 58 | static void keyring_revoke(struct key *keyring); |
1da177e4 LT |
59 | static void keyring_destroy(struct key *keyring); |
60 | static void keyring_describe(const struct key *keyring, struct seq_file *m); | |
61 | static long keyring_read(const struct key *keyring, | |
62 | char __user *buffer, size_t buflen); | |
63 | ||
64 | struct key_type key_type_keyring = { | |
65 | .name = "keyring", | |
66 | .def_datalen = sizeof(struct keyring_list), | |
67 | .instantiate = keyring_instantiate, | |
1da177e4 | 68 | .match = keyring_match, |
31204ed9 | 69 | .revoke = keyring_revoke, |
1da177e4 LT |
70 | .destroy = keyring_destroy, |
71 | .describe = keyring_describe, | |
72 | .read = keyring_read, | |
73 | }; | |
74 | ||
7318226e DH |
75 | EXPORT_SYMBOL(key_type_keyring); |
76 | ||
1da177e4 LT |
77 | /* |
78 | * semaphore to serialise link/link calls to prevent two link calls in parallel | |
79 | * introducing a cycle | |
80 | */ | |
1ae8f407 | 81 | static DECLARE_RWSEM(keyring_serialise_link_sem); |
1da177e4 LT |
82 | |
83 | /*****************************************************************************/ | |
84 | /* | |
85 | * publish the name of a keyring so that it can be found by name (if it has | |
86 | * one) | |
87 | */ | |
69664cf1 | 88 | static void keyring_publish_name(struct key *keyring) |
1da177e4 LT |
89 | { |
90 | int bucket; | |
91 | ||
92 | if (keyring->description) { | |
93 | bucket = keyring_hash(keyring->description); | |
94 | ||
95 | write_lock(&keyring_name_lock); | |
96 | ||
97 | if (!keyring_name_hash[bucket].next) | |
98 | INIT_LIST_HEAD(&keyring_name_hash[bucket]); | |
99 | ||
100 | list_add_tail(&keyring->type_data.link, | |
101 | &keyring_name_hash[bucket]); | |
102 | ||
103 | write_unlock(&keyring_name_lock); | |
104 | } | |
105 | ||
106 | } /* end keyring_publish_name() */ | |
107 | ||
108 | /*****************************************************************************/ | |
109 | /* | |
110 | * initialise a keyring | |
111 | * - we object if we were given any data | |
112 | */ | |
113 | static int keyring_instantiate(struct key *keyring, | |
114 | const void *data, size_t datalen) | |
115 | { | |
116 | int ret; | |
117 | ||
118 | ret = -EINVAL; | |
119 | if (datalen == 0) { | |
120 | /* make the keyring available by name if it has one */ | |
121 | keyring_publish_name(keyring); | |
122 | ret = 0; | |
123 | } | |
124 | ||
125 | return ret; | |
126 | ||
127 | } /* end keyring_instantiate() */ | |
128 | ||
1da177e4 LT |
129 | /*****************************************************************************/ |
130 | /* | |
131 | * match keyrings on their name | |
132 | */ | |
133 | static int keyring_match(const struct key *keyring, const void *description) | |
134 | { | |
135 | return keyring->description && | |
136 | strcmp(keyring->description, description) == 0; | |
137 | ||
138 | } /* end keyring_match() */ | |
139 | ||
140 | /*****************************************************************************/ | |
141 | /* | |
142 | * dispose of the data dangling from the corpse of a keyring | |
143 | */ | |
144 | static void keyring_destroy(struct key *keyring) | |
145 | { | |
146 | struct keyring_list *klist; | |
147 | int loop; | |
148 | ||
149 | if (keyring->description) { | |
150 | write_lock(&keyring_name_lock); | |
94efe72f DH |
151 | |
152 | if (keyring->type_data.link.next != NULL && | |
153 | !list_empty(&keyring->type_data.link)) | |
154 | list_del(&keyring->type_data.link); | |
155 | ||
1da177e4 LT |
156 | write_unlock(&keyring_name_lock); |
157 | } | |
158 | ||
e7b0a61b PM |
159 | klist = rcu_dereference_check(keyring->payload.subscriptions, |
160 | rcu_read_lock_held() || | |
161 | atomic_read(&keyring->usage) == 0); | |
1da177e4 LT |
162 | if (klist) { |
163 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
164 | key_put(klist->keys[loop]); | |
165 | kfree(klist); | |
166 | } | |
167 | ||
168 | } /* end keyring_destroy() */ | |
169 | ||
170 | /*****************************************************************************/ | |
171 | /* | |
172 | * describe the keyring | |
173 | */ | |
174 | static void keyring_describe(const struct key *keyring, struct seq_file *m) | |
175 | { | |
176 | struct keyring_list *klist; | |
177 | ||
178 | if (keyring->description) { | |
179 | seq_puts(m, keyring->description); | |
180 | } | |
181 | else { | |
182 | seq_puts(m, "[anon]"); | |
183 | } | |
184 | ||
76d8aeab DH |
185 | rcu_read_lock(); |
186 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
187 | if (klist) |
188 | seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys); | |
189 | else | |
190 | seq_puts(m, ": empty"); | |
76d8aeab | 191 | rcu_read_unlock(); |
1da177e4 LT |
192 | |
193 | } /* end keyring_describe() */ | |
194 | ||
195 | /*****************************************************************************/ | |
196 | /* | |
197 | * read a list of key IDs from the keyring's contents | |
76d8aeab | 198 | * - the keyring's semaphore is read-locked |
1da177e4 LT |
199 | */ |
200 | static long keyring_read(const struct key *keyring, | |
201 | char __user *buffer, size_t buflen) | |
202 | { | |
203 | struct keyring_list *klist; | |
204 | struct key *key; | |
205 | size_t qty, tmp; | |
206 | int loop, ret; | |
207 | ||
208 | ret = 0; | |
f0641cba | 209 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
210 | if (klist) { |
211 | /* calculate how much data we could return */ | |
212 | qty = klist->nkeys * sizeof(key_serial_t); | |
213 | ||
214 | if (buffer && buflen > 0) { | |
215 | if (buflen > qty) | |
216 | buflen = qty; | |
217 | ||
218 | /* copy the IDs of the subscribed keys into the | |
219 | * buffer */ | |
220 | ret = -EFAULT; | |
221 | ||
222 | for (loop = 0; loop < klist->nkeys; loop++) { | |
223 | key = klist->keys[loop]; | |
224 | ||
225 | tmp = sizeof(key_serial_t); | |
226 | if (tmp > buflen) | |
227 | tmp = buflen; | |
228 | ||
229 | if (copy_to_user(buffer, | |
230 | &key->serial, | |
231 | tmp) != 0) | |
232 | goto error; | |
233 | ||
234 | buflen -= tmp; | |
235 | if (buflen == 0) | |
236 | break; | |
237 | buffer += tmp; | |
238 | } | |
239 | } | |
240 | ||
241 | ret = qty; | |
242 | } | |
243 | ||
244 | error: | |
245 | return ret; | |
246 | ||
247 | } /* end keyring_read() */ | |
248 | ||
249 | /*****************************************************************************/ | |
250 | /* | |
251 | * allocate a keyring and link into the destination keyring | |
252 | */ | |
253 | struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, | |
d84f4f99 | 254 | const struct cred *cred, unsigned long flags, |
d720024e | 255 | struct key *dest) |
1da177e4 LT |
256 | { |
257 | struct key *keyring; | |
258 | int ret; | |
259 | ||
260 | keyring = key_alloc(&key_type_keyring, description, | |
d84f4f99 | 261 | uid, gid, cred, |
29db9190 | 262 | (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, |
7e047ef5 | 263 | flags); |
1da177e4 LT |
264 | |
265 | if (!IS_ERR(keyring)) { | |
3e30148c | 266 | ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); |
1da177e4 LT |
267 | if (ret < 0) { |
268 | key_put(keyring); | |
269 | keyring = ERR_PTR(ret); | |
270 | } | |
271 | } | |
272 | ||
273 | return keyring; | |
274 | ||
275 | } /* end keyring_alloc() */ | |
276 | ||
277 | /*****************************************************************************/ | |
278 | /* | |
279 | * search the supplied keyring tree for a key that matches the criterion | |
280 | * - perform a breadth-then-depth search up to the prescribed limit | |
281 | * - we only find keys on which we have search permission | |
282 | * - we use the supplied match function to see if the description (or other | |
283 | * feature of interest) matches | |
3e30148c | 284 | * - we rely on RCU to prevent the keyring lists from disappearing on us |
1da177e4 LT |
285 | * - we return -EAGAIN if we didn't find any matching key |
286 | * - we return -ENOKEY if we only found negative matching keys | |
664cceb0 | 287 | * - we propagate the possession attribute from the keyring ref to the key ref |
1da177e4 | 288 | */ |
664cceb0 | 289 | key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
d84f4f99 | 290 | const struct cred *cred, |
664cceb0 DH |
291 | struct key_type *type, |
292 | const void *description, | |
293 | key_match_func_t match) | |
1da177e4 LT |
294 | { |
295 | struct { | |
76d8aeab | 296 | struct keyring_list *keylist; |
1da177e4 LT |
297 | int kix; |
298 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
299 | ||
300 | struct keyring_list *keylist; | |
301 | struct timespec now; | |
dceba994 | 302 | unsigned long possessed, kflags; |
664cceb0 DH |
303 | struct key *keyring, *key; |
304 | key_ref_t key_ref; | |
1da177e4 | 305 | long err; |
76d8aeab | 306 | int sp, kix; |
1da177e4 | 307 | |
664cceb0 DH |
308 | keyring = key_ref_to_ptr(keyring_ref); |
309 | possessed = is_key_possessed(keyring_ref); | |
1da177e4 LT |
310 | key_check(keyring); |
311 | ||
312 | /* top keyring must have search permission to begin the search */ | |
d84f4f99 | 313 | err = key_task_permission(keyring_ref, cred, KEY_SEARCH); |
29db9190 DH |
314 | if (err < 0) { |
315 | key_ref = ERR_PTR(err); | |
1da177e4 | 316 | goto error; |
29db9190 | 317 | } |
1da177e4 | 318 | |
664cceb0 | 319 | key_ref = ERR_PTR(-ENOTDIR); |
1da177e4 LT |
320 | if (keyring->type != &key_type_keyring) |
321 | goto error; | |
322 | ||
664cceb0 DH |
323 | rcu_read_lock(); |
324 | ||
1da177e4 LT |
325 | now = current_kernel_time(); |
326 | err = -EAGAIN; | |
327 | sp = 0; | |
328 | ||
dceba994 KC |
329 | /* firstly we should check to see if this top-level keyring is what we |
330 | * are looking for */ | |
331 | key_ref = ERR_PTR(-EAGAIN); | |
332 | kflags = keyring->flags; | |
333 | if (keyring->type == type && match(keyring, description)) { | |
334 | key = keyring; | |
335 | ||
336 | /* check it isn't negative and hasn't expired or been | |
337 | * revoked */ | |
338 | if (kflags & (1 << KEY_FLAG_REVOKED)) | |
339 | goto error_2; | |
340 | if (key->expiry && now.tv_sec >= key->expiry) | |
341 | goto error_2; | |
342 | key_ref = ERR_PTR(-ENOKEY); | |
343 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) | |
344 | goto error_2; | |
345 | goto found; | |
346 | } | |
347 | ||
348 | /* otherwise, the top keyring must not be revoked, expired, or | |
349 | * negatively instantiated if we are to search it */ | |
350 | key_ref = ERR_PTR(-EAGAIN); | |
351 | if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) || | |
352 | (keyring->expiry && now.tv_sec >= keyring->expiry)) | |
353 | goto error_2; | |
354 | ||
1da177e4 | 355 | /* start processing a new keyring */ |
664cceb0 | 356 | descend: |
76d8aeab | 357 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
358 | goto not_this_keyring; |
359 | ||
76d8aeab | 360 | keylist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
361 | if (!keylist) |
362 | goto not_this_keyring; | |
363 | ||
364 | /* iterate through the keys in this keyring first */ | |
365 | for (kix = 0; kix < keylist->nkeys; kix++) { | |
366 | key = keylist->keys[kix]; | |
dceba994 | 367 | kflags = key->flags; |
1da177e4 LT |
368 | |
369 | /* ignore keys not of this type */ | |
370 | if (key->type != type) | |
371 | continue; | |
372 | ||
373 | /* skip revoked keys and expired keys */ | |
dceba994 | 374 | if (kflags & (1 << KEY_FLAG_REVOKED)) |
1da177e4 LT |
375 | continue; |
376 | ||
377 | if (key->expiry && now.tv_sec >= key->expiry) | |
378 | continue; | |
379 | ||
380 | /* keys that don't match */ | |
381 | if (!match(key, description)) | |
382 | continue; | |
383 | ||
384 | /* key must have search permissions */ | |
29db9190 | 385 | if (key_task_permission(make_key_ref(key, possessed), |
d84f4f99 | 386 | cred, KEY_SEARCH) < 0) |
1da177e4 LT |
387 | continue; |
388 | ||
dceba994 KC |
389 | /* we set a different error code if we pass a negative key */ |
390 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) { | |
1da177e4 LT |
391 | err = -ENOKEY; |
392 | continue; | |
393 | } | |
394 | ||
395 | goto found; | |
396 | } | |
397 | ||
398 | /* search through the keyrings nested in this one */ | |
399 | kix = 0; | |
664cceb0 | 400 | ascend: |
76d8aeab | 401 | for (; kix < keylist->nkeys; kix++) { |
1da177e4 LT |
402 | key = keylist->keys[kix]; |
403 | if (key->type != &key_type_keyring) | |
76d8aeab | 404 | continue; |
1da177e4 LT |
405 | |
406 | /* recursively search nested keyrings | |
407 | * - only search keyrings for which we have search permission | |
408 | */ | |
409 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
76d8aeab | 410 | continue; |
1da177e4 | 411 | |
0f6ed7c2 | 412 | if (key_task_permission(make_key_ref(key, possessed), |
d84f4f99 | 413 | cred, KEY_SEARCH) < 0) |
76d8aeab | 414 | continue; |
1da177e4 LT |
415 | |
416 | /* stack the current position */ | |
76d8aeab | 417 | stack[sp].keylist = keylist; |
1da177e4 LT |
418 | stack[sp].kix = kix; |
419 | sp++; | |
420 | ||
421 | /* begin again with the new keyring */ | |
422 | keyring = key; | |
423 | goto descend; | |
1da177e4 LT |
424 | } |
425 | ||
426 | /* the keyring we're looking at was disqualified or didn't contain a | |
427 | * matching key */ | |
664cceb0 | 428 | not_this_keyring: |
1da177e4 LT |
429 | if (sp > 0) { |
430 | /* resume the processing of a keyring higher up in the tree */ | |
431 | sp--; | |
76d8aeab | 432 | keylist = stack[sp].keylist; |
1da177e4 LT |
433 | kix = stack[sp].kix + 1; |
434 | goto ascend; | |
435 | } | |
436 | ||
664cceb0 DH |
437 | key_ref = ERR_PTR(err); |
438 | goto error_2; | |
1da177e4 LT |
439 | |
440 | /* we found a viable match */ | |
664cceb0 | 441 | found: |
1da177e4 | 442 | atomic_inc(&key->usage); |
1da177e4 | 443 | key_check(key); |
664cceb0 DH |
444 | key_ref = make_key_ref(key, possessed); |
445 | error_2: | |
76d8aeab | 446 | rcu_read_unlock(); |
664cceb0 DH |
447 | error: |
448 | return key_ref; | |
1da177e4 LT |
449 | |
450 | } /* end keyring_search_aux() */ | |
451 | ||
452 | /*****************************************************************************/ | |
453 | /* | |
454 | * search the supplied keyring tree for a key that matches the criterion | |
455 | * - perform a breadth-then-depth search up to the prescribed limit | |
456 | * - we only find keys on which we have search permission | |
457 | * - we readlock the keyrings as we search down the tree | |
458 | * - we return -EAGAIN if we didn't find any matching key | |
459 | * - we return -ENOKEY if we only found negative matching keys | |
460 | */ | |
664cceb0 DH |
461 | key_ref_t keyring_search(key_ref_t keyring, |
462 | struct key_type *type, | |
463 | const char *description) | |
1da177e4 | 464 | { |
3e30148c DH |
465 | if (!type->match) |
466 | return ERR_PTR(-ENOKEY); | |
467 | ||
d84f4f99 | 468 | return keyring_search_aux(keyring, current->cred, |
3e30148c | 469 | type, description, type->match); |
1da177e4 LT |
470 | |
471 | } /* end keyring_search() */ | |
472 | ||
473 | EXPORT_SYMBOL(keyring_search); | |
474 | ||
475 | /*****************************************************************************/ | |
476 | /* | |
477 | * search the given keyring only (no recursion) | |
478 | * - keyring must be locked by caller | |
c3a9d654 | 479 | * - caller must guarantee that the keyring is a keyring |
1da177e4 | 480 | */ |
664cceb0 DH |
481 | key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
482 | const struct key_type *ktype, | |
483 | const char *description, | |
484 | key_perm_t perm) | |
1da177e4 LT |
485 | { |
486 | struct keyring_list *klist; | |
664cceb0 DH |
487 | unsigned long possessed; |
488 | struct key *keyring, *key; | |
1da177e4 LT |
489 | int loop; |
490 | ||
664cceb0 DH |
491 | keyring = key_ref_to_ptr(keyring_ref); |
492 | possessed = is_key_possessed(keyring_ref); | |
493 | ||
76d8aeab DH |
494 | rcu_read_lock(); |
495 | ||
496 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
497 | if (klist) { |
498 | for (loop = 0; loop < klist->nkeys; loop++) { | |
499 | key = klist->keys[loop]; | |
500 | ||
501 | if (key->type == ktype && | |
3e30148c DH |
502 | (!key->type->match || |
503 | key->type->match(key, description)) && | |
664cceb0 | 504 | key_permission(make_key_ref(key, possessed), |
db1d1d57 | 505 | perm) == 0 && |
76d8aeab | 506 | !test_bit(KEY_FLAG_REVOKED, &key->flags) |
1da177e4 LT |
507 | ) |
508 | goto found; | |
509 | } | |
510 | } | |
511 | ||
664cceb0 DH |
512 | rcu_read_unlock(); |
513 | return ERR_PTR(-ENOKEY); | |
1da177e4 LT |
514 | |
515 | found: | |
516 | atomic_inc(&key->usage); | |
76d8aeab | 517 | rcu_read_unlock(); |
664cceb0 | 518 | return make_key_ref(key, possessed); |
1da177e4 LT |
519 | |
520 | } /* end __keyring_search_one() */ | |
521 | ||
522 | /*****************************************************************************/ | |
523 | /* | |
524 | * find a keyring with the specified name | |
525 | * - all named keyrings are searched | |
69664cf1 | 526 | * - normally only finds keyrings with search permission for the current process |
1da177e4 | 527 | */ |
69664cf1 | 528 | struct key *find_keyring_by_name(const char *name, bool skip_perm_check) |
1da177e4 LT |
529 | { |
530 | struct key *keyring; | |
531 | int bucket; | |
532 | ||
1da177e4 | 533 | if (!name) |
cea7daa3 | 534 | return ERR_PTR(-EINVAL); |
1da177e4 LT |
535 | |
536 | bucket = keyring_hash(name); | |
537 | ||
538 | read_lock(&keyring_name_lock); | |
539 | ||
540 | if (keyring_name_hash[bucket].next) { | |
541 | /* search this hash bucket for a keyring with a matching name | |
542 | * that's readable and that hasn't been revoked */ | |
543 | list_for_each_entry(keyring, | |
544 | &keyring_name_hash[bucket], | |
545 | type_data.link | |
546 | ) { | |
2ea190d0 SH |
547 | if (keyring->user->user_ns != current_user_ns()) |
548 | continue; | |
549 | ||
76d8aeab | 550 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
551 | continue; |
552 | ||
553 | if (strcmp(keyring->description, name) != 0) | |
554 | continue; | |
555 | ||
69664cf1 DH |
556 | if (!skip_perm_check && |
557 | key_permission(make_key_ref(keyring, 0), | |
0f6ed7c2 | 558 | KEY_SEARCH) < 0) |
1da177e4 LT |
559 | continue; |
560 | ||
cea7daa3 TO |
561 | /* we've got a match but we might end up racing with |
562 | * key_cleanup() if the keyring is currently 'dead' | |
563 | * (ie. it has a zero usage count) */ | |
564 | if (!atomic_inc_not_zero(&keyring->usage)) | |
565 | continue; | |
566 | goto out; | |
1da177e4 LT |
567 | } |
568 | } | |
569 | ||
1da177e4 | 570 | keyring = ERR_PTR(-ENOKEY); |
cea7daa3 TO |
571 | out: |
572 | read_unlock(&keyring_name_lock); | |
1da177e4 LT |
573 | return keyring; |
574 | ||
575 | } /* end find_keyring_by_name() */ | |
576 | ||
577 | /*****************************************************************************/ | |
578 | /* | |
579 | * see if a cycle will will be created by inserting acyclic tree B in acyclic | |
580 | * tree A at the topmost level (ie: as a direct child of A) | |
581 | * - since we are adding B to A at the top level, checking for cycles should | |
582 | * just be a matter of seeing if node A is somewhere in tree B | |
583 | */ | |
584 | static int keyring_detect_cycle(struct key *A, struct key *B) | |
585 | { | |
586 | struct { | |
76d8aeab | 587 | struct keyring_list *keylist; |
1da177e4 LT |
588 | int kix; |
589 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
590 | ||
591 | struct keyring_list *keylist; | |
592 | struct key *subtree, *key; | |
593 | int sp, kix, ret; | |
594 | ||
76d8aeab DH |
595 | rcu_read_lock(); |
596 | ||
1da177e4 LT |
597 | ret = -EDEADLK; |
598 | if (A == B) | |
76d8aeab | 599 | goto cycle_detected; |
1da177e4 LT |
600 | |
601 | subtree = B; | |
602 | sp = 0; | |
603 | ||
604 | /* start processing a new keyring */ | |
605 | descend: | |
76d8aeab | 606 | if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
1da177e4 LT |
607 | goto not_this_keyring; |
608 | ||
76d8aeab | 609 | keylist = rcu_dereference(subtree->payload.subscriptions); |
1da177e4 LT |
610 | if (!keylist) |
611 | goto not_this_keyring; | |
612 | kix = 0; | |
613 | ||
614 | ascend: | |
615 | /* iterate through the remaining keys in this keyring */ | |
616 | for (; kix < keylist->nkeys; kix++) { | |
617 | key = keylist->keys[kix]; | |
618 | ||
619 | if (key == A) | |
620 | goto cycle_detected; | |
621 | ||
622 | /* recursively check nested keyrings */ | |
623 | if (key->type == &key_type_keyring) { | |
624 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
625 | goto too_deep; | |
626 | ||
627 | /* stack the current position */ | |
76d8aeab | 628 | stack[sp].keylist = keylist; |
1da177e4 LT |
629 | stack[sp].kix = kix; |
630 | sp++; | |
631 | ||
632 | /* begin again with the new keyring */ | |
633 | subtree = key; | |
634 | goto descend; | |
635 | } | |
636 | } | |
637 | ||
638 | /* the keyring we're looking at was disqualified or didn't contain a | |
639 | * matching key */ | |
640 | not_this_keyring: | |
1da177e4 LT |
641 | if (sp > 0) { |
642 | /* resume the checking of a keyring higher up in the tree */ | |
643 | sp--; | |
76d8aeab | 644 | keylist = stack[sp].keylist; |
1da177e4 LT |
645 | kix = stack[sp].kix + 1; |
646 | goto ascend; | |
647 | } | |
648 | ||
649 | ret = 0; /* no cycles detected */ | |
650 | ||
651 | error: | |
76d8aeab | 652 | rcu_read_unlock(); |
1da177e4 LT |
653 | return ret; |
654 | ||
655 | too_deep: | |
656 | ret = -ELOOP; | |
76d8aeab DH |
657 | goto error; |
658 | ||
1da177e4 LT |
659 | cycle_detected: |
660 | ret = -EDEADLK; | |
1da177e4 LT |
661 | goto error; |
662 | ||
663 | } /* end keyring_detect_cycle() */ | |
664 | ||
76d8aeab DH |
665 | /*****************************************************************************/ |
666 | /* | |
667 | * dispose of a keyring list after the RCU grace period | |
668 | */ | |
669 | static void keyring_link_rcu_disposal(struct rcu_head *rcu) | |
670 | { | |
671 | struct keyring_list *klist = | |
672 | container_of(rcu, struct keyring_list, rcu); | |
673 | ||
674 | kfree(klist); | |
675 | ||
676 | } /* end keyring_link_rcu_disposal() */ | |
677 | ||
cab8eb59 DH |
678 | /*****************************************************************************/ |
679 | /* | |
680 | * dispose of a keyring list after the RCU grace period, freeing the unlinked | |
681 | * key | |
682 | */ | |
683 | static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) | |
684 | { | |
685 | struct keyring_list *klist = | |
686 | container_of(rcu, struct keyring_list, rcu); | |
687 | ||
688 | key_put(klist->keys[klist->delkey]); | |
689 | kfree(klist); | |
690 | ||
691 | } /* end keyring_unlink_rcu_disposal() */ | |
692 | ||
1da177e4 LT |
693 | /*****************************************************************************/ |
694 | /* | |
695 | * link a key into to a keyring | |
76d8aeab | 696 | * - must be called with the keyring's semaphore write-locked |
cab8eb59 | 697 | * - discard already extant link to matching key if there is one |
1da177e4 LT |
698 | */ |
699 | int __key_link(struct key *keyring, struct key *key) | |
700 | { | |
701 | struct keyring_list *klist, *nklist; | |
702 | unsigned max; | |
703 | size_t size; | |
cab8eb59 | 704 | int loop, ret; |
1da177e4 LT |
705 | |
706 | ret = -EKEYREVOKED; | |
76d8aeab | 707 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
708 | goto error; |
709 | ||
710 | ret = -ENOTDIR; | |
711 | if (keyring->type != &key_type_keyring) | |
712 | goto error; | |
713 | ||
714 | /* serialise link/link calls to prevent parallel calls causing a | |
715 | * cycle when applied to two keyring in opposite orders */ | |
716 | down_write(&keyring_serialise_link_sem); | |
717 | ||
718 | /* check that we aren't going to create a cycle adding one keyring to | |
719 | * another */ | |
720 | if (key->type == &key_type_keyring) { | |
721 | ret = keyring_detect_cycle(keyring, key); | |
722 | if (ret < 0) | |
723 | goto error2; | |
724 | } | |
725 | ||
cab8eb59 | 726 | /* see if there's a matching key we can displace */ |
f0641cba | 727 | klist = rcu_dereference_locked_keyring(keyring); |
cab8eb59 DH |
728 | if (klist && klist->nkeys > 0) { |
729 | struct key_type *type = key->type; | |
730 | ||
731 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { | |
732 | if (klist->keys[loop]->type == type && | |
733 | strcmp(klist->keys[loop]->description, | |
734 | key->description) == 0 | |
735 | ) { | |
736 | /* found a match - replace with new key */ | |
737 | size = sizeof(struct key *) * klist->maxkeys; | |
738 | size += sizeof(*klist); | |
739 | BUG_ON(size > PAGE_SIZE); | |
740 | ||
741 | ret = -ENOMEM; | |
48ad504e | 742 | nklist = kmemdup(klist, size, GFP_KERNEL); |
cab8eb59 DH |
743 | if (!nklist) |
744 | goto error2; | |
745 | ||
cab8eb59 DH |
746 | /* replace matched key */ |
747 | atomic_inc(&key->usage); | |
748 | nklist->keys[loop] = key; | |
749 | ||
750 | rcu_assign_pointer( | |
751 | keyring->payload.subscriptions, | |
752 | nklist); | |
753 | ||
754 | /* dispose of the old keyring list and the | |
755 | * displaced key */ | |
756 | klist->delkey = loop; | |
757 | call_rcu(&klist->rcu, | |
758 | keyring_unlink_rcu_disposal); | |
759 | ||
760 | goto done; | |
761 | } | |
762 | } | |
763 | } | |
764 | ||
1da177e4 LT |
765 | /* check that we aren't going to overrun the user's quota */ |
766 | ret = key_payload_reserve(keyring, | |
767 | keyring->datalen + KEYQUOTA_LINK_BYTES); | |
768 | if (ret < 0) | |
769 | goto error2; | |
770 | ||
1da177e4 LT |
771 | if (klist && klist->nkeys < klist->maxkeys) { |
772 | /* there's sufficient slack space to add directly */ | |
773 | atomic_inc(&key->usage); | |
774 | ||
76d8aeab DH |
775 | klist->keys[klist->nkeys] = key; |
776 | smp_wmb(); | |
777 | klist->nkeys++; | |
778 | smp_wmb(); | |
1da177e4 LT |
779 | } |
780 | else { | |
781 | /* grow the key list */ | |
782 | max = 4; | |
783 | if (klist) | |
784 | max += klist->maxkeys; | |
785 | ||
786 | ret = -ENFILE; | |
76d8aeab DH |
787 | if (max > 65535) |
788 | goto error3; | |
a4014d8f | 789 | size = sizeof(*klist) + sizeof(struct key *) * max; |
1da177e4 LT |
790 | if (size > PAGE_SIZE) |
791 | goto error3; | |
792 | ||
793 | ret = -ENOMEM; | |
794 | nklist = kmalloc(size, GFP_KERNEL); | |
795 | if (!nklist) | |
796 | goto error3; | |
797 | nklist->maxkeys = max; | |
798 | nklist->nkeys = 0; | |
799 | ||
800 | if (klist) { | |
801 | nklist->nkeys = klist->nkeys; | |
802 | memcpy(nklist->keys, | |
803 | klist->keys, | |
804 | sizeof(struct key *) * klist->nkeys); | |
805 | } | |
806 | ||
807 | /* add the key into the new space */ | |
808 | atomic_inc(&key->usage); | |
1da177e4 | 809 | nklist->keys[nklist->nkeys++] = key; |
76d8aeab DH |
810 | |
811 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); | |
1da177e4 LT |
812 | |
813 | /* dispose of the old keyring list */ | |
76d8aeab DH |
814 | if (klist) |
815 | call_rcu(&klist->rcu, keyring_link_rcu_disposal); | |
1da177e4 LT |
816 | } |
817 | ||
cab8eb59 DH |
818 | done: |
819 | ret = 0; | |
820 | error2: | |
1da177e4 | 821 | up_write(&keyring_serialise_link_sem); |
cab8eb59 | 822 | error: |
1da177e4 LT |
823 | return ret; |
824 | ||
cab8eb59 | 825 | error3: |
1da177e4 LT |
826 | /* undo the quota changes */ |
827 | key_payload_reserve(keyring, | |
828 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
829 | goto error2; | |
830 | ||
831 | } /* end __key_link() */ | |
832 | ||
833 | /*****************************************************************************/ | |
834 | /* | |
835 | * link a key to a keyring | |
836 | */ | |
837 | int key_link(struct key *keyring, struct key *key) | |
838 | { | |
839 | int ret; | |
840 | ||
841 | key_check(keyring); | |
842 | key_check(key); | |
843 | ||
844 | down_write(&keyring->sem); | |
845 | ret = __key_link(keyring, key); | |
846 | up_write(&keyring->sem); | |
847 | ||
848 | return ret; | |
849 | ||
850 | } /* end key_link() */ | |
851 | ||
852 | EXPORT_SYMBOL(key_link); | |
853 | ||
854 | /*****************************************************************************/ | |
855 | /* | |
856 | * unlink the first link to a key from a keyring | |
857 | */ | |
858 | int key_unlink(struct key *keyring, struct key *key) | |
859 | { | |
76d8aeab | 860 | struct keyring_list *klist, *nklist; |
1da177e4 LT |
861 | int loop, ret; |
862 | ||
863 | key_check(keyring); | |
864 | key_check(key); | |
865 | ||
866 | ret = -ENOTDIR; | |
867 | if (keyring->type != &key_type_keyring) | |
868 | goto error; | |
869 | ||
870 | down_write(&keyring->sem); | |
871 | ||
f0641cba | 872 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
873 | if (klist) { |
874 | /* search the keyring for the key */ | |
875 | for (loop = 0; loop < klist->nkeys; loop++) | |
876 | if (klist->keys[loop] == key) | |
877 | goto key_is_present; | |
878 | } | |
879 | ||
880 | up_write(&keyring->sem); | |
881 | ret = -ENOENT; | |
882 | goto error; | |
883 | ||
76d8aeab DH |
884 | key_is_present: |
885 | /* we need to copy the key list for RCU purposes */ | |
a4014d8f DH |
886 | nklist = kmalloc(sizeof(*klist) + |
887 | sizeof(struct key *) * klist->maxkeys, | |
76d8aeab DH |
888 | GFP_KERNEL); |
889 | if (!nklist) | |
890 | goto nomem; | |
891 | nklist->maxkeys = klist->maxkeys; | |
892 | nklist->nkeys = klist->nkeys - 1; | |
893 | ||
894 | if (loop > 0) | |
895 | memcpy(&nklist->keys[0], | |
896 | &klist->keys[0], | |
a4014d8f | 897 | loop * sizeof(struct key *)); |
76d8aeab DH |
898 | |
899 | if (loop < nklist->nkeys) | |
900 | memcpy(&nklist->keys[loop], | |
901 | &klist->keys[loop + 1], | |
a4014d8f | 902 | (nklist->nkeys - loop) * sizeof(struct key *)); |
76d8aeab | 903 | |
1da177e4 LT |
904 | /* adjust the user's quota */ |
905 | key_payload_reserve(keyring, | |
906 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
907 | ||
76d8aeab | 908 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
1da177e4 | 909 | |
76d8aeab | 910 | up_write(&keyring->sem); |
1da177e4 | 911 | |
76d8aeab DH |
912 | /* schedule for later cleanup */ |
913 | klist->delkey = loop; | |
914 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
1da177e4 | 915 | |
1da177e4 LT |
916 | ret = 0; |
917 | ||
76d8aeab | 918 | error: |
1da177e4 | 919 | return ret; |
76d8aeab DH |
920 | nomem: |
921 | ret = -ENOMEM; | |
922 | up_write(&keyring->sem); | |
923 | goto error; | |
1da177e4 LT |
924 | |
925 | } /* end key_unlink() */ | |
926 | ||
927 | EXPORT_SYMBOL(key_unlink); | |
928 | ||
76d8aeab DH |
929 | /*****************************************************************************/ |
930 | /* | |
931 | * dispose of a keyring list after the RCU grace period, releasing the keys it | |
932 | * links to | |
933 | */ | |
934 | static void keyring_clear_rcu_disposal(struct rcu_head *rcu) | |
935 | { | |
936 | struct keyring_list *klist; | |
937 | int loop; | |
938 | ||
939 | klist = container_of(rcu, struct keyring_list, rcu); | |
940 | ||
941 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
942 | key_put(klist->keys[loop]); | |
943 | ||
944 | kfree(klist); | |
945 | ||
946 | } /* end keyring_clear_rcu_disposal() */ | |
947 | ||
1da177e4 LT |
948 | /*****************************************************************************/ |
949 | /* | |
950 | * clear the specified process keyring | |
951 | * - implements keyctl(KEYCTL_CLEAR) | |
952 | */ | |
953 | int keyring_clear(struct key *keyring) | |
954 | { | |
955 | struct keyring_list *klist; | |
76d8aeab | 956 | int ret; |
1da177e4 LT |
957 | |
958 | ret = -ENOTDIR; | |
959 | if (keyring->type == &key_type_keyring) { | |
960 | /* detach the pointer block with the locks held */ | |
961 | down_write(&keyring->sem); | |
962 | ||
f0641cba | 963 | klist = rcu_dereference_locked_keyring(keyring); |
1da177e4 LT |
964 | if (klist) { |
965 | /* adjust the quota */ | |
966 | key_payload_reserve(keyring, | |
967 | sizeof(struct keyring_list)); | |
968 | ||
76d8aeab DH |
969 | rcu_assign_pointer(keyring->payload.subscriptions, |
970 | NULL); | |
1da177e4 LT |
971 | } |
972 | ||
973 | up_write(&keyring->sem); | |
974 | ||
975 | /* free the keys after the locks have been dropped */ | |
76d8aeab DH |
976 | if (klist) |
977 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1da177e4 LT |
978 | |
979 | ret = 0; | |
980 | } | |
981 | ||
982 | return ret; | |
983 | ||
984 | } /* end keyring_clear() */ | |
985 | ||
986 | EXPORT_SYMBOL(keyring_clear); | |
31204ed9 DH |
987 | |
988 | /*****************************************************************************/ | |
989 | /* | |
990 | * dispose of the links from a revoked keyring | |
991 | * - called with the key sem write-locked | |
992 | */ | |
993 | static void keyring_revoke(struct key *keyring) | |
994 | { | |
f0641cba DH |
995 | struct keyring_list *klist; |
996 | ||
997 | klist = rcu_dereference_locked_keyring(keyring); | |
31204ed9 DH |
998 | |
999 | /* adjust the quota */ | |
1000 | key_payload_reserve(keyring, 0); | |
1001 | ||
1002 | if (klist) { | |
1003 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1004 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1005 | } | |
1006 | ||
1007 | } /* end keyring_revoke() */ | |
5d135440 DH |
1008 | |
1009 | /* | |
1010 | * Determine whether a key is dead | |
1011 | */ | |
1012 | static bool key_is_dead(struct key *key, time_t limit) | |
1013 | { | |
1014 | return test_bit(KEY_FLAG_DEAD, &key->flags) || | |
1015 | (key->expiry > 0 && key->expiry <= limit); | |
1016 | } | |
1017 | ||
1018 | /* | |
1019 | * Collect garbage from the contents of a keyring | |
1020 | */ | |
1021 | void keyring_gc(struct key *keyring, time_t limit) | |
1022 | { | |
1023 | struct keyring_list *klist, *new; | |
1024 | struct key *key; | |
1025 | int loop, keep, max; | |
1026 | ||
c08ef808 | 1027 | kenter("{%x,%s}", key_serial(keyring), keyring->description); |
5d135440 DH |
1028 | |
1029 | down_write(&keyring->sem); | |
1030 | ||
f0641cba | 1031 | klist = rcu_dereference_locked_keyring(keyring); |
5d135440 | 1032 | if (!klist) |
c08ef808 | 1033 | goto no_klist; |
5d135440 DH |
1034 | |
1035 | /* work out how many subscriptions we're keeping */ | |
1036 | keep = 0; | |
1037 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
c08ef808 | 1038 | if (!key_is_dead(klist->keys[loop], limit)) |
5d135440 DH |
1039 | keep++; |
1040 | ||
1041 | if (keep == klist->nkeys) | |
1042 | goto just_return; | |
1043 | ||
1044 | /* allocate a new keyring payload */ | |
1045 | max = roundup(keep, 4); | |
1046 | new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *), | |
1047 | GFP_KERNEL); | |
1048 | if (!new) | |
c08ef808 | 1049 | goto nomem; |
5d135440 DH |
1050 | new->maxkeys = max; |
1051 | new->nkeys = 0; | |
1052 | new->delkey = 0; | |
1053 | ||
1054 | /* install the live keys | |
1055 | * - must take care as expired keys may be updated back to life | |
1056 | */ | |
1057 | keep = 0; | |
1058 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { | |
1059 | key = klist->keys[loop]; | |
1060 | if (!key_is_dead(key, limit)) { | |
1061 | if (keep >= max) | |
1062 | goto discard_new; | |
1063 | new->keys[keep++] = key_get(key); | |
1064 | } | |
1065 | } | |
1066 | new->nkeys = keep; | |
1067 | ||
1068 | /* adjust the quota */ | |
1069 | key_payload_reserve(keyring, | |
1070 | sizeof(struct keyring_list) + | |
1071 | KEYQUOTA_LINK_BYTES * keep); | |
1072 | ||
1073 | if (keep == 0) { | |
1074 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1075 | kfree(new); | |
1076 | } else { | |
1077 | rcu_assign_pointer(keyring->payload.subscriptions, new); | |
1078 | } | |
1079 | ||
1080 | up_write(&keyring->sem); | |
1081 | ||
1082 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1083 | kleave(" [yes]"); | |
1084 | return; | |
1085 | ||
1086 | discard_new: | |
1087 | new->nkeys = keep; | |
1088 | keyring_clear_rcu_disposal(&new->rcu); | |
c08ef808 DH |
1089 | up_write(&keyring->sem); |
1090 | kleave(" [discard]"); | |
1091 | return; | |
1092 | ||
5d135440 DH |
1093 | just_return: |
1094 | up_write(&keyring->sem); | |
c08ef808 DH |
1095 | kleave(" [no dead]"); |
1096 | return; | |
1097 | ||
1098 | no_klist: | |
1099 | up_write(&keyring->sem); | |
1100 | kleave(" [no_klist]"); | |
1101 | return; | |
1102 | ||
1103 | nomem: | |
1104 | up_write(&keyring->sem); | |
1105 | kleave(" [oom]"); | |
5d135440 | 1106 | } |