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> |
1da177e4 LT |
20 | #include <asm/uaccess.h> |
21 | #include "internal.h" | |
22 | ||
23 | /* | |
24 | * when plumbing the depths of the key tree, this sets a hard limit set on how | |
25 | * deep we're willing to go | |
26 | */ | |
27 | #define KEYRING_SEARCH_MAX_DEPTH 6 | |
28 | ||
29 | /* | |
30 | * we keep all named keyrings in a hash to speed looking them up | |
31 | */ | |
32 | #define KEYRING_NAME_HASH_SIZE (1 << 5) | |
33 | ||
34 | static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE]; | |
35 | static DEFINE_RWLOCK(keyring_name_lock); | |
36 | ||
37 | static inline unsigned keyring_hash(const char *desc) | |
38 | { | |
39 | unsigned bucket = 0; | |
40 | ||
41 | for (; *desc; desc++) | |
42 | bucket += (unsigned char) *desc; | |
43 | ||
44 | return bucket & (KEYRING_NAME_HASH_SIZE - 1); | |
45 | } | |
46 | ||
47 | /* | |
48 | * the keyring type definition | |
49 | */ | |
50 | static int keyring_instantiate(struct key *keyring, | |
51 | const void *data, size_t datalen); | |
1da177e4 | 52 | static int keyring_match(const struct key *keyring, const void *criterion); |
31204ed9 | 53 | static void keyring_revoke(struct key *keyring); |
1da177e4 LT |
54 | static void keyring_destroy(struct key *keyring); |
55 | static void keyring_describe(const struct key *keyring, struct seq_file *m); | |
56 | static long keyring_read(const struct key *keyring, | |
57 | char __user *buffer, size_t buflen); | |
58 | ||
59 | struct key_type key_type_keyring = { | |
60 | .name = "keyring", | |
61 | .def_datalen = sizeof(struct keyring_list), | |
62 | .instantiate = keyring_instantiate, | |
1da177e4 | 63 | .match = keyring_match, |
31204ed9 | 64 | .revoke = keyring_revoke, |
1da177e4 LT |
65 | .destroy = keyring_destroy, |
66 | .describe = keyring_describe, | |
67 | .read = keyring_read, | |
68 | }; | |
69 | ||
7318226e DH |
70 | EXPORT_SYMBOL(key_type_keyring); |
71 | ||
1da177e4 LT |
72 | /* |
73 | * semaphore to serialise link/link calls to prevent two link calls in parallel | |
74 | * introducing a cycle | |
75 | */ | |
1ae8f407 | 76 | static DECLARE_RWSEM(keyring_serialise_link_sem); |
1da177e4 LT |
77 | |
78 | /*****************************************************************************/ | |
79 | /* | |
80 | * publish the name of a keyring so that it can be found by name (if it has | |
81 | * one) | |
82 | */ | |
69664cf1 | 83 | static void keyring_publish_name(struct key *keyring) |
1da177e4 LT |
84 | { |
85 | int bucket; | |
86 | ||
87 | if (keyring->description) { | |
88 | bucket = keyring_hash(keyring->description); | |
89 | ||
90 | write_lock(&keyring_name_lock); | |
91 | ||
92 | if (!keyring_name_hash[bucket].next) | |
93 | INIT_LIST_HEAD(&keyring_name_hash[bucket]); | |
94 | ||
95 | list_add_tail(&keyring->type_data.link, | |
96 | &keyring_name_hash[bucket]); | |
97 | ||
98 | write_unlock(&keyring_name_lock); | |
99 | } | |
100 | ||
101 | } /* end keyring_publish_name() */ | |
102 | ||
103 | /*****************************************************************************/ | |
104 | /* | |
105 | * initialise a keyring | |
106 | * - we object if we were given any data | |
107 | */ | |
108 | static int keyring_instantiate(struct key *keyring, | |
109 | const void *data, size_t datalen) | |
110 | { | |
111 | int ret; | |
112 | ||
113 | ret = -EINVAL; | |
114 | if (datalen == 0) { | |
115 | /* make the keyring available by name if it has one */ | |
116 | keyring_publish_name(keyring); | |
117 | ret = 0; | |
118 | } | |
119 | ||
120 | return ret; | |
121 | ||
122 | } /* end keyring_instantiate() */ | |
123 | ||
1da177e4 LT |
124 | /*****************************************************************************/ |
125 | /* | |
126 | * match keyrings on their name | |
127 | */ | |
128 | static int keyring_match(const struct key *keyring, const void *description) | |
129 | { | |
130 | return keyring->description && | |
131 | strcmp(keyring->description, description) == 0; | |
132 | ||
133 | } /* end keyring_match() */ | |
134 | ||
135 | /*****************************************************************************/ | |
136 | /* | |
137 | * dispose of the data dangling from the corpse of a keyring | |
138 | */ | |
139 | static void keyring_destroy(struct key *keyring) | |
140 | { | |
141 | struct keyring_list *klist; | |
142 | int loop; | |
143 | ||
144 | if (keyring->description) { | |
145 | write_lock(&keyring_name_lock); | |
94efe72f DH |
146 | |
147 | if (keyring->type_data.link.next != NULL && | |
148 | !list_empty(&keyring->type_data.link)) | |
149 | list_del(&keyring->type_data.link); | |
150 | ||
1da177e4 LT |
151 | write_unlock(&keyring_name_lock); |
152 | } | |
153 | ||
e7b0a61b PM |
154 | klist = rcu_dereference_check(keyring->payload.subscriptions, |
155 | rcu_read_lock_held() || | |
156 | atomic_read(&keyring->usage) == 0); | |
1da177e4 LT |
157 | if (klist) { |
158 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
159 | key_put(klist->keys[loop]); | |
160 | kfree(klist); | |
161 | } | |
162 | ||
163 | } /* end keyring_destroy() */ | |
164 | ||
165 | /*****************************************************************************/ | |
166 | /* | |
167 | * describe the keyring | |
168 | */ | |
169 | static void keyring_describe(const struct key *keyring, struct seq_file *m) | |
170 | { | |
171 | struct keyring_list *klist; | |
172 | ||
173 | if (keyring->description) { | |
174 | seq_puts(m, keyring->description); | |
175 | } | |
176 | else { | |
177 | seq_puts(m, "[anon]"); | |
178 | } | |
179 | ||
76d8aeab DH |
180 | rcu_read_lock(); |
181 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
182 | if (klist) |
183 | seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys); | |
184 | else | |
185 | seq_puts(m, ": empty"); | |
76d8aeab | 186 | rcu_read_unlock(); |
1da177e4 LT |
187 | |
188 | } /* end keyring_describe() */ | |
189 | ||
190 | /*****************************************************************************/ | |
191 | /* | |
192 | * read a list of key IDs from the keyring's contents | |
76d8aeab | 193 | * - the keyring's semaphore is read-locked |
1da177e4 LT |
194 | */ |
195 | static long keyring_read(const struct key *keyring, | |
196 | char __user *buffer, size_t buflen) | |
197 | { | |
198 | struct keyring_list *klist; | |
199 | struct key *key; | |
200 | size_t qty, tmp; | |
201 | int loop, ret; | |
202 | ||
203 | ret = 0; | |
b59ec78c | 204 | klist = keyring->payload.subscriptions; |
1da177e4 LT |
205 | |
206 | if (klist) { | |
207 | /* calculate how much data we could return */ | |
208 | qty = klist->nkeys * sizeof(key_serial_t); | |
209 | ||
210 | if (buffer && buflen > 0) { | |
211 | if (buflen > qty) | |
212 | buflen = qty; | |
213 | ||
214 | /* copy the IDs of the subscribed keys into the | |
215 | * buffer */ | |
216 | ret = -EFAULT; | |
217 | ||
218 | for (loop = 0; loop < klist->nkeys; loop++) { | |
219 | key = klist->keys[loop]; | |
220 | ||
221 | tmp = sizeof(key_serial_t); | |
222 | if (tmp > buflen) | |
223 | tmp = buflen; | |
224 | ||
225 | if (copy_to_user(buffer, | |
226 | &key->serial, | |
227 | tmp) != 0) | |
228 | goto error; | |
229 | ||
230 | buflen -= tmp; | |
231 | if (buflen == 0) | |
232 | break; | |
233 | buffer += tmp; | |
234 | } | |
235 | } | |
236 | ||
237 | ret = qty; | |
238 | } | |
239 | ||
240 | error: | |
241 | return ret; | |
242 | ||
243 | } /* end keyring_read() */ | |
244 | ||
245 | /*****************************************************************************/ | |
246 | /* | |
247 | * allocate a keyring and link into the destination keyring | |
248 | */ | |
249 | struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, | |
d84f4f99 | 250 | const struct cred *cred, unsigned long flags, |
d720024e | 251 | struct key *dest) |
1da177e4 LT |
252 | { |
253 | struct key *keyring; | |
254 | int ret; | |
255 | ||
256 | keyring = key_alloc(&key_type_keyring, description, | |
d84f4f99 | 257 | uid, gid, cred, |
29db9190 | 258 | (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, |
7e047ef5 | 259 | flags); |
1da177e4 LT |
260 | |
261 | if (!IS_ERR(keyring)) { | |
3e30148c | 262 | ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); |
1da177e4 LT |
263 | if (ret < 0) { |
264 | key_put(keyring); | |
265 | keyring = ERR_PTR(ret); | |
266 | } | |
267 | } | |
268 | ||
269 | return keyring; | |
270 | ||
271 | } /* end keyring_alloc() */ | |
272 | ||
273 | /*****************************************************************************/ | |
274 | /* | |
275 | * search the supplied keyring tree for a key that matches the criterion | |
276 | * - perform a breadth-then-depth search up to the prescribed limit | |
277 | * - we only find keys on which we have search permission | |
278 | * - we use the supplied match function to see if the description (or other | |
279 | * feature of interest) matches | |
3e30148c | 280 | * - we rely on RCU to prevent the keyring lists from disappearing on us |
1da177e4 LT |
281 | * - we return -EAGAIN if we didn't find any matching key |
282 | * - we return -ENOKEY if we only found negative matching keys | |
664cceb0 | 283 | * - we propagate the possession attribute from the keyring ref to the key ref |
1da177e4 | 284 | */ |
664cceb0 | 285 | key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
d84f4f99 | 286 | const struct cred *cred, |
664cceb0 DH |
287 | struct key_type *type, |
288 | const void *description, | |
289 | key_match_func_t match) | |
1da177e4 LT |
290 | { |
291 | struct { | |
76d8aeab | 292 | struct keyring_list *keylist; |
1da177e4 LT |
293 | int kix; |
294 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
295 | ||
296 | struct keyring_list *keylist; | |
297 | struct timespec now; | |
dceba994 | 298 | unsigned long possessed, kflags; |
664cceb0 DH |
299 | struct key *keyring, *key; |
300 | key_ref_t key_ref; | |
1da177e4 | 301 | long err; |
76d8aeab | 302 | int sp, kix; |
1da177e4 | 303 | |
664cceb0 DH |
304 | keyring = key_ref_to_ptr(keyring_ref); |
305 | possessed = is_key_possessed(keyring_ref); | |
1da177e4 LT |
306 | key_check(keyring); |
307 | ||
308 | /* top keyring must have search permission to begin the search */ | |
d84f4f99 | 309 | err = key_task_permission(keyring_ref, cred, KEY_SEARCH); |
29db9190 DH |
310 | if (err < 0) { |
311 | key_ref = ERR_PTR(err); | |
1da177e4 | 312 | goto error; |
29db9190 | 313 | } |
1da177e4 | 314 | |
664cceb0 | 315 | key_ref = ERR_PTR(-ENOTDIR); |
1da177e4 LT |
316 | if (keyring->type != &key_type_keyring) |
317 | goto error; | |
318 | ||
664cceb0 DH |
319 | rcu_read_lock(); |
320 | ||
1da177e4 LT |
321 | now = current_kernel_time(); |
322 | err = -EAGAIN; | |
323 | sp = 0; | |
324 | ||
dceba994 KC |
325 | /* firstly we should check to see if this top-level keyring is what we |
326 | * are looking for */ | |
327 | key_ref = ERR_PTR(-EAGAIN); | |
328 | kflags = keyring->flags; | |
329 | if (keyring->type == type && match(keyring, description)) { | |
330 | key = keyring; | |
331 | ||
332 | /* check it isn't negative and hasn't expired or been | |
333 | * revoked */ | |
334 | if (kflags & (1 << KEY_FLAG_REVOKED)) | |
335 | goto error_2; | |
336 | if (key->expiry && now.tv_sec >= key->expiry) | |
337 | goto error_2; | |
338 | key_ref = ERR_PTR(-ENOKEY); | |
339 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) | |
340 | goto error_2; | |
341 | goto found; | |
342 | } | |
343 | ||
344 | /* otherwise, the top keyring must not be revoked, expired, or | |
345 | * negatively instantiated if we are to search it */ | |
346 | key_ref = ERR_PTR(-EAGAIN); | |
347 | if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) || | |
348 | (keyring->expiry && now.tv_sec >= keyring->expiry)) | |
349 | goto error_2; | |
350 | ||
1da177e4 | 351 | /* start processing a new keyring */ |
664cceb0 | 352 | descend: |
76d8aeab | 353 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
354 | goto not_this_keyring; |
355 | ||
76d8aeab | 356 | keylist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
357 | if (!keylist) |
358 | goto not_this_keyring; | |
359 | ||
360 | /* iterate through the keys in this keyring first */ | |
361 | for (kix = 0; kix < keylist->nkeys; kix++) { | |
362 | key = keylist->keys[kix]; | |
dceba994 | 363 | kflags = key->flags; |
1da177e4 LT |
364 | |
365 | /* ignore keys not of this type */ | |
366 | if (key->type != type) | |
367 | continue; | |
368 | ||
369 | /* skip revoked keys and expired keys */ | |
dceba994 | 370 | if (kflags & (1 << KEY_FLAG_REVOKED)) |
1da177e4 LT |
371 | continue; |
372 | ||
373 | if (key->expiry && now.tv_sec >= key->expiry) | |
374 | continue; | |
375 | ||
376 | /* keys that don't match */ | |
377 | if (!match(key, description)) | |
378 | continue; | |
379 | ||
380 | /* key must have search permissions */ | |
29db9190 | 381 | if (key_task_permission(make_key_ref(key, possessed), |
d84f4f99 | 382 | cred, KEY_SEARCH) < 0) |
1da177e4 LT |
383 | continue; |
384 | ||
dceba994 KC |
385 | /* we set a different error code if we pass a negative key */ |
386 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) { | |
1da177e4 LT |
387 | err = -ENOKEY; |
388 | continue; | |
389 | } | |
390 | ||
391 | goto found; | |
392 | } | |
393 | ||
394 | /* search through the keyrings nested in this one */ | |
395 | kix = 0; | |
664cceb0 | 396 | ascend: |
76d8aeab | 397 | for (; kix < keylist->nkeys; kix++) { |
1da177e4 LT |
398 | key = keylist->keys[kix]; |
399 | if (key->type != &key_type_keyring) | |
76d8aeab | 400 | continue; |
1da177e4 LT |
401 | |
402 | /* recursively search nested keyrings | |
403 | * - only search keyrings for which we have search permission | |
404 | */ | |
405 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
76d8aeab | 406 | continue; |
1da177e4 | 407 | |
0f6ed7c2 | 408 | if (key_task_permission(make_key_ref(key, possessed), |
d84f4f99 | 409 | cred, KEY_SEARCH) < 0) |
76d8aeab | 410 | continue; |
1da177e4 LT |
411 | |
412 | /* stack the current position */ | |
76d8aeab | 413 | stack[sp].keylist = keylist; |
1da177e4 LT |
414 | stack[sp].kix = kix; |
415 | sp++; | |
416 | ||
417 | /* begin again with the new keyring */ | |
418 | keyring = key; | |
419 | goto descend; | |
1da177e4 LT |
420 | } |
421 | ||
422 | /* the keyring we're looking at was disqualified or didn't contain a | |
423 | * matching key */ | |
664cceb0 | 424 | not_this_keyring: |
1da177e4 LT |
425 | if (sp > 0) { |
426 | /* resume the processing of a keyring higher up in the tree */ | |
427 | sp--; | |
76d8aeab | 428 | keylist = stack[sp].keylist; |
1da177e4 LT |
429 | kix = stack[sp].kix + 1; |
430 | goto ascend; | |
431 | } | |
432 | ||
664cceb0 DH |
433 | key_ref = ERR_PTR(err); |
434 | goto error_2; | |
1da177e4 LT |
435 | |
436 | /* we found a viable match */ | |
664cceb0 | 437 | found: |
1da177e4 | 438 | atomic_inc(&key->usage); |
1da177e4 | 439 | key_check(key); |
664cceb0 DH |
440 | key_ref = make_key_ref(key, possessed); |
441 | error_2: | |
76d8aeab | 442 | rcu_read_unlock(); |
664cceb0 DH |
443 | error: |
444 | return key_ref; | |
1da177e4 LT |
445 | |
446 | } /* end keyring_search_aux() */ | |
447 | ||
448 | /*****************************************************************************/ | |
449 | /* | |
450 | * search the supplied keyring tree for a key that matches the criterion | |
451 | * - perform a breadth-then-depth search up to the prescribed limit | |
452 | * - we only find keys on which we have search permission | |
453 | * - we readlock the keyrings as we search down the tree | |
454 | * - we return -EAGAIN if we didn't find any matching key | |
455 | * - we return -ENOKEY if we only found negative matching keys | |
456 | */ | |
664cceb0 DH |
457 | key_ref_t keyring_search(key_ref_t keyring, |
458 | struct key_type *type, | |
459 | const char *description) | |
1da177e4 | 460 | { |
3e30148c DH |
461 | if (!type->match) |
462 | return ERR_PTR(-ENOKEY); | |
463 | ||
d84f4f99 | 464 | return keyring_search_aux(keyring, current->cred, |
3e30148c | 465 | type, description, type->match); |
1da177e4 LT |
466 | |
467 | } /* end keyring_search() */ | |
468 | ||
469 | EXPORT_SYMBOL(keyring_search); | |
470 | ||
471 | /*****************************************************************************/ | |
472 | /* | |
473 | * search the given keyring only (no recursion) | |
474 | * - keyring must be locked by caller | |
c3a9d654 | 475 | * - caller must guarantee that the keyring is a keyring |
1da177e4 | 476 | */ |
664cceb0 DH |
477 | key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
478 | const struct key_type *ktype, | |
479 | const char *description, | |
480 | key_perm_t perm) | |
1da177e4 LT |
481 | { |
482 | struct keyring_list *klist; | |
664cceb0 DH |
483 | unsigned long possessed; |
484 | struct key *keyring, *key; | |
1da177e4 LT |
485 | int loop; |
486 | ||
664cceb0 DH |
487 | keyring = key_ref_to_ptr(keyring_ref); |
488 | possessed = is_key_possessed(keyring_ref); | |
489 | ||
76d8aeab DH |
490 | rcu_read_lock(); |
491 | ||
492 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
493 | if (klist) { |
494 | for (loop = 0; loop < klist->nkeys; loop++) { | |
495 | key = klist->keys[loop]; | |
496 | ||
497 | if (key->type == ktype && | |
3e30148c DH |
498 | (!key->type->match || |
499 | key->type->match(key, description)) && | |
664cceb0 | 500 | key_permission(make_key_ref(key, possessed), |
db1d1d57 | 501 | perm) == 0 && |
76d8aeab | 502 | !test_bit(KEY_FLAG_REVOKED, &key->flags) |
1da177e4 LT |
503 | ) |
504 | goto found; | |
505 | } | |
506 | } | |
507 | ||
664cceb0 DH |
508 | rcu_read_unlock(); |
509 | return ERR_PTR(-ENOKEY); | |
1da177e4 LT |
510 | |
511 | found: | |
512 | atomic_inc(&key->usage); | |
76d8aeab | 513 | rcu_read_unlock(); |
664cceb0 | 514 | return make_key_ref(key, possessed); |
1da177e4 LT |
515 | |
516 | } /* end __keyring_search_one() */ | |
517 | ||
518 | /*****************************************************************************/ | |
519 | /* | |
520 | * find a keyring with the specified name | |
521 | * - all named keyrings are searched | |
69664cf1 | 522 | * - normally only finds keyrings with search permission for the current process |
1da177e4 | 523 | */ |
69664cf1 | 524 | struct key *find_keyring_by_name(const char *name, bool skip_perm_check) |
1da177e4 LT |
525 | { |
526 | struct key *keyring; | |
527 | int bucket; | |
528 | ||
1da177e4 | 529 | if (!name) |
cea7daa3 | 530 | return ERR_PTR(-EINVAL); |
1da177e4 LT |
531 | |
532 | bucket = keyring_hash(name); | |
533 | ||
534 | read_lock(&keyring_name_lock); | |
535 | ||
536 | if (keyring_name_hash[bucket].next) { | |
537 | /* search this hash bucket for a keyring with a matching name | |
538 | * that's readable and that hasn't been revoked */ | |
539 | list_for_each_entry(keyring, | |
540 | &keyring_name_hash[bucket], | |
541 | type_data.link | |
542 | ) { | |
2ea190d0 SH |
543 | if (keyring->user->user_ns != current_user_ns()) |
544 | continue; | |
545 | ||
76d8aeab | 546 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
547 | continue; |
548 | ||
549 | if (strcmp(keyring->description, name) != 0) | |
550 | continue; | |
551 | ||
69664cf1 DH |
552 | if (!skip_perm_check && |
553 | key_permission(make_key_ref(keyring, 0), | |
0f6ed7c2 | 554 | KEY_SEARCH) < 0) |
1da177e4 LT |
555 | continue; |
556 | ||
cea7daa3 TO |
557 | /* we've got a match but we might end up racing with |
558 | * key_cleanup() if the keyring is currently 'dead' | |
559 | * (ie. it has a zero usage count) */ | |
560 | if (!atomic_inc_not_zero(&keyring->usage)) | |
561 | continue; | |
562 | goto out; | |
1da177e4 LT |
563 | } |
564 | } | |
565 | ||
1da177e4 | 566 | keyring = ERR_PTR(-ENOKEY); |
cea7daa3 TO |
567 | out: |
568 | read_unlock(&keyring_name_lock); | |
1da177e4 LT |
569 | return keyring; |
570 | ||
571 | } /* end find_keyring_by_name() */ | |
572 | ||
573 | /*****************************************************************************/ | |
574 | /* | |
575 | * see if a cycle will will be created by inserting acyclic tree B in acyclic | |
576 | * tree A at the topmost level (ie: as a direct child of A) | |
577 | * - since we are adding B to A at the top level, checking for cycles should | |
578 | * just be a matter of seeing if node A is somewhere in tree B | |
579 | */ | |
580 | static int keyring_detect_cycle(struct key *A, struct key *B) | |
581 | { | |
582 | struct { | |
76d8aeab | 583 | struct keyring_list *keylist; |
1da177e4 LT |
584 | int kix; |
585 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
586 | ||
587 | struct keyring_list *keylist; | |
588 | struct key *subtree, *key; | |
589 | int sp, kix, ret; | |
590 | ||
76d8aeab DH |
591 | rcu_read_lock(); |
592 | ||
1da177e4 LT |
593 | ret = -EDEADLK; |
594 | if (A == B) | |
76d8aeab | 595 | goto cycle_detected; |
1da177e4 LT |
596 | |
597 | subtree = B; | |
598 | sp = 0; | |
599 | ||
600 | /* start processing a new keyring */ | |
601 | descend: | |
76d8aeab | 602 | if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
1da177e4 LT |
603 | goto not_this_keyring; |
604 | ||
76d8aeab | 605 | keylist = rcu_dereference(subtree->payload.subscriptions); |
1da177e4 LT |
606 | if (!keylist) |
607 | goto not_this_keyring; | |
608 | kix = 0; | |
609 | ||
610 | ascend: | |
611 | /* iterate through the remaining keys in this keyring */ | |
612 | for (; kix < keylist->nkeys; kix++) { | |
613 | key = keylist->keys[kix]; | |
614 | ||
615 | if (key == A) | |
616 | goto cycle_detected; | |
617 | ||
618 | /* recursively check nested keyrings */ | |
619 | if (key->type == &key_type_keyring) { | |
620 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
621 | goto too_deep; | |
622 | ||
623 | /* stack the current position */ | |
76d8aeab | 624 | stack[sp].keylist = keylist; |
1da177e4 LT |
625 | stack[sp].kix = kix; |
626 | sp++; | |
627 | ||
628 | /* begin again with the new keyring */ | |
629 | subtree = key; | |
630 | goto descend; | |
631 | } | |
632 | } | |
633 | ||
634 | /* the keyring we're looking at was disqualified or didn't contain a | |
635 | * matching key */ | |
636 | not_this_keyring: | |
1da177e4 LT |
637 | if (sp > 0) { |
638 | /* resume the checking of a keyring higher up in the tree */ | |
639 | sp--; | |
76d8aeab | 640 | keylist = stack[sp].keylist; |
1da177e4 LT |
641 | kix = stack[sp].kix + 1; |
642 | goto ascend; | |
643 | } | |
644 | ||
645 | ret = 0; /* no cycles detected */ | |
646 | ||
647 | error: | |
76d8aeab | 648 | rcu_read_unlock(); |
1da177e4 LT |
649 | return ret; |
650 | ||
651 | too_deep: | |
652 | ret = -ELOOP; | |
76d8aeab DH |
653 | goto error; |
654 | ||
1da177e4 LT |
655 | cycle_detected: |
656 | ret = -EDEADLK; | |
1da177e4 LT |
657 | goto error; |
658 | ||
659 | } /* end keyring_detect_cycle() */ | |
660 | ||
76d8aeab DH |
661 | /*****************************************************************************/ |
662 | /* | |
663 | * dispose of a keyring list after the RCU grace period | |
664 | */ | |
665 | static void keyring_link_rcu_disposal(struct rcu_head *rcu) | |
666 | { | |
667 | struct keyring_list *klist = | |
668 | container_of(rcu, struct keyring_list, rcu); | |
669 | ||
670 | kfree(klist); | |
671 | ||
672 | } /* end keyring_link_rcu_disposal() */ | |
673 | ||
cab8eb59 DH |
674 | /*****************************************************************************/ |
675 | /* | |
676 | * dispose of a keyring list after the RCU grace period, freeing the unlinked | |
677 | * key | |
678 | */ | |
679 | static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) | |
680 | { | |
681 | struct keyring_list *klist = | |
682 | container_of(rcu, struct keyring_list, rcu); | |
683 | ||
684 | key_put(klist->keys[klist->delkey]); | |
685 | kfree(klist); | |
686 | ||
687 | } /* end keyring_unlink_rcu_disposal() */ | |
688 | ||
1da177e4 LT |
689 | /*****************************************************************************/ |
690 | /* | |
691 | * link a key into to a keyring | |
76d8aeab | 692 | * - must be called with the keyring's semaphore write-locked |
cab8eb59 | 693 | * - discard already extant link to matching key if there is one |
1da177e4 LT |
694 | */ |
695 | int __key_link(struct key *keyring, struct key *key) | |
696 | { | |
697 | struct keyring_list *klist, *nklist; | |
698 | unsigned max; | |
699 | size_t size; | |
cab8eb59 | 700 | int loop, ret; |
1da177e4 LT |
701 | |
702 | ret = -EKEYREVOKED; | |
76d8aeab | 703 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
704 | goto error; |
705 | ||
706 | ret = -ENOTDIR; | |
707 | if (keyring->type != &key_type_keyring) | |
708 | goto error; | |
709 | ||
710 | /* serialise link/link calls to prevent parallel calls causing a | |
711 | * cycle when applied to two keyring in opposite orders */ | |
712 | down_write(&keyring_serialise_link_sem); | |
713 | ||
714 | /* check that we aren't going to create a cycle adding one keyring to | |
715 | * another */ | |
716 | if (key->type == &key_type_keyring) { | |
717 | ret = keyring_detect_cycle(keyring, key); | |
718 | if (ret < 0) | |
719 | goto error2; | |
720 | } | |
721 | ||
cab8eb59 DH |
722 | /* see if there's a matching key we can displace */ |
723 | klist = keyring->payload.subscriptions; | |
724 | ||
725 | if (klist && klist->nkeys > 0) { | |
726 | struct key_type *type = key->type; | |
727 | ||
728 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { | |
729 | if (klist->keys[loop]->type == type && | |
730 | strcmp(klist->keys[loop]->description, | |
731 | key->description) == 0 | |
732 | ) { | |
733 | /* found a match - replace with new key */ | |
734 | size = sizeof(struct key *) * klist->maxkeys; | |
735 | size += sizeof(*klist); | |
736 | BUG_ON(size > PAGE_SIZE); | |
737 | ||
738 | ret = -ENOMEM; | |
48ad504e | 739 | nklist = kmemdup(klist, size, GFP_KERNEL); |
cab8eb59 DH |
740 | if (!nklist) |
741 | goto error2; | |
742 | ||
cab8eb59 DH |
743 | /* replace matched key */ |
744 | atomic_inc(&key->usage); | |
745 | nklist->keys[loop] = key; | |
746 | ||
747 | rcu_assign_pointer( | |
748 | keyring->payload.subscriptions, | |
749 | nklist); | |
750 | ||
751 | /* dispose of the old keyring list and the | |
752 | * displaced key */ | |
753 | klist->delkey = loop; | |
754 | call_rcu(&klist->rcu, | |
755 | keyring_unlink_rcu_disposal); | |
756 | ||
757 | goto done; | |
758 | } | |
759 | } | |
760 | } | |
761 | ||
1da177e4 LT |
762 | /* check that we aren't going to overrun the user's quota */ |
763 | ret = key_payload_reserve(keyring, | |
764 | keyring->datalen + KEYQUOTA_LINK_BYTES); | |
765 | if (ret < 0) | |
766 | goto error2; | |
767 | ||
768 | klist = keyring->payload.subscriptions; | |
769 | ||
770 | if (klist && klist->nkeys < klist->maxkeys) { | |
771 | /* there's sufficient slack space to add directly */ | |
772 | atomic_inc(&key->usage); | |
773 | ||
76d8aeab DH |
774 | klist->keys[klist->nkeys] = key; |
775 | smp_wmb(); | |
776 | klist->nkeys++; | |
777 | smp_wmb(); | |
1da177e4 LT |
778 | } |
779 | else { | |
780 | /* grow the key list */ | |
781 | max = 4; | |
782 | if (klist) | |
783 | max += klist->maxkeys; | |
784 | ||
785 | ret = -ENFILE; | |
76d8aeab DH |
786 | if (max > 65535) |
787 | goto error3; | |
a4014d8f | 788 | size = sizeof(*klist) + sizeof(struct key *) * max; |
1da177e4 LT |
789 | if (size > PAGE_SIZE) |
790 | goto error3; | |
791 | ||
792 | ret = -ENOMEM; | |
793 | nklist = kmalloc(size, GFP_KERNEL); | |
794 | if (!nklist) | |
795 | goto error3; | |
796 | nklist->maxkeys = max; | |
797 | nklist->nkeys = 0; | |
798 | ||
799 | if (klist) { | |
800 | nklist->nkeys = klist->nkeys; | |
801 | memcpy(nklist->keys, | |
802 | klist->keys, | |
803 | sizeof(struct key *) * klist->nkeys); | |
804 | } | |
805 | ||
806 | /* add the key into the new space */ | |
807 | atomic_inc(&key->usage); | |
1da177e4 | 808 | nklist->keys[nklist->nkeys++] = key; |
76d8aeab DH |
809 | |
810 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); | |
1da177e4 LT |
811 | |
812 | /* dispose of the old keyring list */ | |
76d8aeab DH |
813 | if (klist) |
814 | call_rcu(&klist->rcu, keyring_link_rcu_disposal); | |
1da177e4 LT |
815 | } |
816 | ||
cab8eb59 DH |
817 | done: |
818 | ret = 0; | |
819 | error2: | |
1da177e4 | 820 | up_write(&keyring_serialise_link_sem); |
cab8eb59 | 821 | error: |
1da177e4 LT |
822 | return ret; |
823 | ||
cab8eb59 | 824 | error3: |
1da177e4 LT |
825 | /* undo the quota changes */ |
826 | key_payload_reserve(keyring, | |
827 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
828 | goto error2; | |
829 | ||
830 | } /* end __key_link() */ | |
831 | ||
832 | /*****************************************************************************/ | |
833 | /* | |
834 | * link a key to a keyring | |
835 | */ | |
836 | int key_link(struct key *keyring, struct key *key) | |
837 | { | |
838 | int ret; | |
839 | ||
840 | key_check(keyring); | |
841 | key_check(key); | |
842 | ||
843 | down_write(&keyring->sem); | |
844 | ret = __key_link(keyring, key); | |
845 | up_write(&keyring->sem); | |
846 | ||
847 | return ret; | |
848 | ||
849 | } /* end key_link() */ | |
850 | ||
851 | EXPORT_SYMBOL(key_link); | |
852 | ||
853 | /*****************************************************************************/ | |
854 | /* | |
855 | * unlink the first link to a key from a keyring | |
856 | */ | |
857 | int key_unlink(struct key *keyring, struct key *key) | |
858 | { | |
76d8aeab | 859 | struct keyring_list *klist, *nklist; |
1da177e4 LT |
860 | int loop, ret; |
861 | ||
862 | key_check(keyring); | |
863 | key_check(key); | |
864 | ||
865 | ret = -ENOTDIR; | |
866 | if (keyring->type != &key_type_keyring) | |
867 | goto error; | |
868 | ||
869 | down_write(&keyring->sem); | |
870 | ||
871 | klist = keyring->payload.subscriptions; | |
872 | if (klist) { | |
873 | /* search the keyring for the key */ | |
874 | for (loop = 0; loop < klist->nkeys; loop++) | |
875 | if (klist->keys[loop] == key) | |
876 | goto key_is_present; | |
877 | } | |
878 | ||
879 | up_write(&keyring->sem); | |
880 | ret = -ENOENT; | |
881 | goto error; | |
882 | ||
76d8aeab DH |
883 | key_is_present: |
884 | /* we need to copy the key list for RCU purposes */ | |
a4014d8f DH |
885 | nklist = kmalloc(sizeof(*klist) + |
886 | sizeof(struct key *) * klist->maxkeys, | |
76d8aeab DH |
887 | GFP_KERNEL); |
888 | if (!nklist) | |
889 | goto nomem; | |
890 | nklist->maxkeys = klist->maxkeys; | |
891 | nklist->nkeys = klist->nkeys - 1; | |
892 | ||
893 | if (loop > 0) | |
894 | memcpy(&nklist->keys[0], | |
895 | &klist->keys[0], | |
a4014d8f | 896 | loop * sizeof(struct key *)); |
76d8aeab DH |
897 | |
898 | if (loop < nklist->nkeys) | |
899 | memcpy(&nklist->keys[loop], | |
900 | &klist->keys[loop + 1], | |
a4014d8f | 901 | (nklist->nkeys - loop) * sizeof(struct key *)); |
76d8aeab | 902 | |
1da177e4 LT |
903 | /* adjust the user's quota */ |
904 | key_payload_reserve(keyring, | |
905 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
906 | ||
76d8aeab | 907 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
1da177e4 | 908 | |
76d8aeab | 909 | up_write(&keyring->sem); |
1da177e4 | 910 | |
76d8aeab DH |
911 | /* schedule for later cleanup */ |
912 | klist->delkey = loop; | |
913 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
1da177e4 | 914 | |
1da177e4 LT |
915 | ret = 0; |
916 | ||
76d8aeab | 917 | error: |
1da177e4 | 918 | return ret; |
76d8aeab DH |
919 | nomem: |
920 | ret = -ENOMEM; | |
921 | up_write(&keyring->sem); | |
922 | goto error; | |
1da177e4 LT |
923 | |
924 | } /* end key_unlink() */ | |
925 | ||
926 | EXPORT_SYMBOL(key_unlink); | |
927 | ||
76d8aeab DH |
928 | /*****************************************************************************/ |
929 | /* | |
930 | * dispose of a keyring list after the RCU grace period, releasing the keys it | |
931 | * links to | |
932 | */ | |
933 | static void keyring_clear_rcu_disposal(struct rcu_head *rcu) | |
934 | { | |
935 | struct keyring_list *klist; | |
936 | int loop; | |
937 | ||
938 | klist = container_of(rcu, struct keyring_list, rcu); | |
939 | ||
940 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
941 | key_put(klist->keys[loop]); | |
942 | ||
943 | kfree(klist); | |
944 | ||
945 | } /* end keyring_clear_rcu_disposal() */ | |
946 | ||
1da177e4 LT |
947 | /*****************************************************************************/ |
948 | /* | |
949 | * clear the specified process keyring | |
950 | * - implements keyctl(KEYCTL_CLEAR) | |
951 | */ | |
952 | int keyring_clear(struct key *keyring) | |
953 | { | |
954 | struct keyring_list *klist; | |
76d8aeab | 955 | int ret; |
1da177e4 LT |
956 | |
957 | ret = -ENOTDIR; | |
958 | if (keyring->type == &key_type_keyring) { | |
959 | /* detach the pointer block with the locks held */ | |
960 | down_write(&keyring->sem); | |
961 | ||
962 | klist = keyring->payload.subscriptions; | |
963 | if (klist) { | |
964 | /* adjust the quota */ | |
965 | key_payload_reserve(keyring, | |
966 | sizeof(struct keyring_list)); | |
967 | ||
76d8aeab DH |
968 | rcu_assign_pointer(keyring->payload.subscriptions, |
969 | NULL); | |
1da177e4 LT |
970 | } |
971 | ||
972 | up_write(&keyring->sem); | |
973 | ||
974 | /* free the keys after the locks have been dropped */ | |
76d8aeab DH |
975 | if (klist) |
976 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1da177e4 LT |
977 | |
978 | ret = 0; | |
979 | } | |
980 | ||
981 | return ret; | |
982 | ||
983 | } /* end keyring_clear() */ | |
984 | ||
985 | EXPORT_SYMBOL(keyring_clear); | |
31204ed9 DH |
986 | |
987 | /*****************************************************************************/ | |
988 | /* | |
989 | * dispose of the links from a revoked keyring | |
990 | * - called with the key sem write-locked | |
991 | */ | |
992 | static void keyring_revoke(struct key *keyring) | |
993 | { | |
994 | struct keyring_list *klist = keyring->payload.subscriptions; | |
995 | ||
996 | /* adjust the quota */ | |
997 | key_payload_reserve(keyring, 0); | |
998 | ||
999 | if (klist) { | |
1000 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1001 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1002 | } | |
1003 | ||
1004 | } /* end keyring_revoke() */ | |
5d135440 DH |
1005 | |
1006 | /* | |
1007 | * Determine whether a key is dead | |
1008 | */ | |
1009 | static bool key_is_dead(struct key *key, time_t limit) | |
1010 | { | |
1011 | return test_bit(KEY_FLAG_DEAD, &key->flags) || | |
1012 | (key->expiry > 0 && key->expiry <= limit); | |
1013 | } | |
1014 | ||
1015 | /* | |
1016 | * Collect garbage from the contents of a keyring | |
1017 | */ | |
1018 | void keyring_gc(struct key *keyring, time_t limit) | |
1019 | { | |
1020 | struct keyring_list *klist, *new; | |
1021 | struct key *key; | |
1022 | int loop, keep, max; | |
1023 | ||
c08ef808 | 1024 | kenter("{%x,%s}", key_serial(keyring), keyring->description); |
5d135440 DH |
1025 | |
1026 | down_write(&keyring->sem); | |
1027 | ||
1028 | klist = keyring->payload.subscriptions; | |
1029 | if (!klist) | |
c08ef808 | 1030 | goto no_klist; |
5d135440 DH |
1031 | |
1032 | /* work out how many subscriptions we're keeping */ | |
1033 | keep = 0; | |
1034 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
c08ef808 | 1035 | if (!key_is_dead(klist->keys[loop], limit)) |
5d135440 DH |
1036 | keep++; |
1037 | ||
1038 | if (keep == klist->nkeys) | |
1039 | goto just_return; | |
1040 | ||
1041 | /* allocate a new keyring payload */ | |
1042 | max = roundup(keep, 4); | |
1043 | new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *), | |
1044 | GFP_KERNEL); | |
1045 | if (!new) | |
c08ef808 | 1046 | goto nomem; |
5d135440 DH |
1047 | new->maxkeys = max; |
1048 | new->nkeys = 0; | |
1049 | new->delkey = 0; | |
1050 | ||
1051 | /* install the live keys | |
1052 | * - must take care as expired keys may be updated back to life | |
1053 | */ | |
1054 | keep = 0; | |
1055 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { | |
1056 | key = klist->keys[loop]; | |
1057 | if (!key_is_dead(key, limit)) { | |
1058 | if (keep >= max) | |
1059 | goto discard_new; | |
1060 | new->keys[keep++] = key_get(key); | |
1061 | } | |
1062 | } | |
1063 | new->nkeys = keep; | |
1064 | ||
1065 | /* adjust the quota */ | |
1066 | key_payload_reserve(keyring, | |
1067 | sizeof(struct keyring_list) + | |
1068 | KEYQUOTA_LINK_BYTES * keep); | |
1069 | ||
1070 | if (keep == 0) { | |
1071 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1072 | kfree(new); | |
1073 | } else { | |
1074 | rcu_assign_pointer(keyring->payload.subscriptions, new); | |
1075 | } | |
1076 | ||
1077 | up_write(&keyring->sem); | |
1078 | ||
1079 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1080 | kleave(" [yes]"); | |
1081 | return; | |
1082 | ||
1083 | discard_new: | |
1084 | new->nkeys = keep; | |
1085 | keyring_clear_rcu_disposal(&new->rcu); | |
c08ef808 DH |
1086 | up_write(&keyring->sem); |
1087 | kleave(" [discard]"); | |
1088 | return; | |
1089 | ||
5d135440 DH |
1090 | just_return: |
1091 | up_write(&keyring->sem); | |
c08ef808 DH |
1092 | kleave(" [no dead]"); |
1093 | return; | |
1094 | ||
1095 | no_klist: | |
1096 | up_write(&keyring->sem); | |
1097 | kleave(" [no_klist]"); | |
1098 | return; | |
1099 | ||
1100 | nomem: | |
1101 | up_write(&keyring->sem); | |
1102 | kleave(" [oom]"); | |
5d135440 | 1103 | } |