Commit | Line | Data |
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1da177e4 LT |
1 | /* keyring.c: keyring handling |
2 | * | |
3e30148c | 3 | * Copyright (C) 2004-5 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> | |
19 | #include <asm/uaccess.h> | |
20 | #include "internal.h" | |
21 | ||
22 | /* | |
23 | * when plumbing the depths of the key tree, this sets a hard limit set on how | |
24 | * deep we're willing to go | |
25 | */ | |
26 | #define KEYRING_SEARCH_MAX_DEPTH 6 | |
27 | ||
28 | /* | |
29 | * we keep all named keyrings in a hash to speed looking them up | |
30 | */ | |
31 | #define KEYRING_NAME_HASH_SIZE (1 << 5) | |
32 | ||
33 | static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE]; | |
34 | static DEFINE_RWLOCK(keyring_name_lock); | |
35 | ||
36 | static inline unsigned keyring_hash(const char *desc) | |
37 | { | |
38 | unsigned bucket = 0; | |
39 | ||
40 | for (; *desc; desc++) | |
41 | bucket += (unsigned char) *desc; | |
42 | ||
43 | return bucket & (KEYRING_NAME_HASH_SIZE - 1); | |
44 | } | |
45 | ||
46 | /* | |
47 | * the keyring type definition | |
48 | */ | |
49 | static int keyring_instantiate(struct key *keyring, | |
50 | const void *data, size_t datalen); | |
1da177e4 | 51 | static int keyring_match(const struct key *keyring, const void *criterion); |
31204ed9 | 52 | static void keyring_revoke(struct key *keyring); |
1da177e4 LT |
53 | static void keyring_destroy(struct key *keyring); |
54 | static void keyring_describe(const struct key *keyring, struct seq_file *m); | |
55 | static long keyring_read(const struct key *keyring, | |
56 | char __user *buffer, size_t buflen); | |
57 | ||
58 | struct key_type key_type_keyring = { | |
59 | .name = "keyring", | |
60 | .def_datalen = sizeof(struct keyring_list), | |
61 | .instantiate = keyring_instantiate, | |
1da177e4 | 62 | .match = keyring_match, |
31204ed9 | 63 | .revoke = keyring_revoke, |
1da177e4 LT |
64 | .destroy = keyring_destroy, |
65 | .describe = keyring_describe, | |
66 | .read = keyring_read, | |
67 | }; | |
68 | ||
7318226e DH |
69 | EXPORT_SYMBOL(key_type_keyring); |
70 | ||
1da177e4 LT |
71 | /* |
72 | * semaphore to serialise link/link calls to prevent two link calls in parallel | |
73 | * introducing a cycle | |
74 | */ | |
1ae8f407 | 75 | static DECLARE_RWSEM(keyring_serialise_link_sem); |
1da177e4 LT |
76 | |
77 | /*****************************************************************************/ | |
78 | /* | |
79 | * publish the name of a keyring so that it can be found by name (if it has | |
80 | * one) | |
81 | */ | |
82 | void keyring_publish_name(struct key *keyring) | |
83 | { | |
84 | int bucket; | |
85 | ||
86 | if (keyring->description) { | |
87 | bucket = keyring_hash(keyring->description); | |
88 | ||
89 | write_lock(&keyring_name_lock); | |
90 | ||
91 | if (!keyring_name_hash[bucket].next) | |
92 | INIT_LIST_HEAD(&keyring_name_hash[bucket]); | |
93 | ||
94 | list_add_tail(&keyring->type_data.link, | |
95 | &keyring_name_hash[bucket]); | |
96 | ||
97 | write_unlock(&keyring_name_lock); | |
98 | } | |
99 | ||
100 | } /* end keyring_publish_name() */ | |
101 | ||
102 | /*****************************************************************************/ | |
103 | /* | |
104 | * initialise a keyring | |
105 | * - we object if we were given any data | |
106 | */ | |
107 | static int keyring_instantiate(struct key *keyring, | |
108 | const void *data, size_t datalen) | |
109 | { | |
110 | int ret; | |
111 | ||
112 | ret = -EINVAL; | |
113 | if (datalen == 0) { | |
114 | /* make the keyring available by name if it has one */ | |
115 | keyring_publish_name(keyring); | |
116 | ret = 0; | |
117 | } | |
118 | ||
119 | return ret; | |
120 | ||
121 | } /* end keyring_instantiate() */ | |
122 | ||
1da177e4 LT |
123 | /*****************************************************************************/ |
124 | /* | |
125 | * match keyrings on their name | |
126 | */ | |
127 | static int keyring_match(const struct key *keyring, const void *description) | |
128 | { | |
129 | return keyring->description && | |
130 | strcmp(keyring->description, description) == 0; | |
131 | ||
132 | } /* end keyring_match() */ | |
133 | ||
134 | /*****************************************************************************/ | |
135 | /* | |
136 | * dispose of the data dangling from the corpse of a keyring | |
137 | */ | |
138 | static void keyring_destroy(struct key *keyring) | |
139 | { | |
140 | struct keyring_list *klist; | |
141 | int loop; | |
142 | ||
143 | if (keyring->description) { | |
144 | write_lock(&keyring_name_lock); | |
94efe72f DH |
145 | |
146 | if (keyring->type_data.link.next != NULL && | |
147 | !list_empty(&keyring->type_data.link)) | |
148 | list_del(&keyring->type_data.link); | |
149 | ||
1da177e4 LT |
150 | write_unlock(&keyring_name_lock); |
151 | } | |
152 | ||
76d8aeab | 153 | klist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
154 | if (klist) { |
155 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
156 | key_put(klist->keys[loop]); | |
157 | kfree(klist); | |
158 | } | |
159 | ||
160 | } /* end keyring_destroy() */ | |
161 | ||
162 | /*****************************************************************************/ | |
163 | /* | |
164 | * describe the keyring | |
165 | */ | |
166 | static void keyring_describe(const struct key *keyring, struct seq_file *m) | |
167 | { | |
168 | struct keyring_list *klist; | |
169 | ||
170 | if (keyring->description) { | |
171 | seq_puts(m, keyring->description); | |
172 | } | |
173 | else { | |
174 | seq_puts(m, "[anon]"); | |
175 | } | |
176 | ||
76d8aeab DH |
177 | rcu_read_lock(); |
178 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
179 | if (klist) |
180 | seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys); | |
181 | else | |
182 | seq_puts(m, ": empty"); | |
76d8aeab | 183 | rcu_read_unlock(); |
1da177e4 LT |
184 | |
185 | } /* end keyring_describe() */ | |
186 | ||
187 | /*****************************************************************************/ | |
188 | /* | |
189 | * read a list of key IDs from the keyring's contents | |
76d8aeab | 190 | * - the keyring's semaphore is read-locked |
1da177e4 LT |
191 | */ |
192 | static long keyring_read(const struct key *keyring, | |
193 | char __user *buffer, size_t buflen) | |
194 | { | |
195 | struct keyring_list *klist; | |
196 | struct key *key; | |
197 | size_t qty, tmp; | |
198 | int loop, ret; | |
199 | ||
200 | ret = 0; | |
76d8aeab | 201 | klist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
202 | |
203 | if (klist) { | |
204 | /* calculate how much data we could return */ | |
205 | qty = klist->nkeys * sizeof(key_serial_t); | |
206 | ||
207 | if (buffer && buflen > 0) { | |
208 | if (buflen > qty) | |
209 | buflen = qty; | |
210 | ||
211 | /* copy the IDs of the subscribed keys into the | |
212 | * buffer */ | |
213 | ret = -EFAULT; | |
214 | ||
215 | for (loop = 0; loop < klist->nkeys; loop++) { | |
216 | key = klist->keys[loop]; | |
217 | ||
218 | tmp = sizeof(key_serial_t); | |
219 | if (tmp > buflen) | |
220 | tmp = buflen; | |
221 | ||
222 | if (copy_to_user(buffer, | |
223 | &key->serial, | |
224 | tmp) != 0) | |
225 | goto error; | |
226 | ||
227 | buflen -= tmp; | |
228 | if (buflen == 0) | |
229 | break; | |
230 | buffer += tmp; | |
231 | } | |
232 | } | |
233 | ||
234 | ret = qty; | |
235 | } | |
236 | ||
237 | error: | |
238 | return ret; | |
239 | ||
240 | } /* end keyring_read() */ | |
241 | ||
242 | /*****************************************************************************/ | |
243 | /* | |
244 | * allocate a keyring and link into the destination keyring | |
245 | */ | |
246 | struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, | |
7e047ef5 | 247 | struct task_struct *ctx, unsigned long flags, |
d720024e | 248 | struct key *dest) |
1da177e4 LT |
249 | { |
250 | struct key *keyring; | |
251 | int ret; | |
252 | ||
253 | keyring = key_alloc(&key_type_keyring, description, | |
d720024e | 254 | uid, gid, ctx, |
29db9190 | 255 | (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL, |
7e047ef5 | 256 | flags); |
1da177e4 LT |
257 | |
258 | if (!IS_ERR(keyring)) { | |
3e30148c | 259 | ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); |
1da177e4 LT |
260 | if (ret < 0) { |
261 | key_put(keyring); | |
262 | keyring = ERR_PTR(ret); | |
263 | } | |
264 | } | |
265 | ||
266 | return keyring; | |
267 | ||
268 | } /* end keyring_alloc() */ | |
269 | ||
270 | /*****************************************************************************/ | |
271 | /* | |
272 | * search the supplied keyring tree for a key that matches the criterion | |
273 | * - perform a breadth-then-depth search up to the prescribed limit | |
274 | * - we only find keys on which we have search permission | |
275 | * - we use the supplied match function to see if the description (or other | |
276 | * feature of interest) matches | |
3e30148c | 277 | * - we rely on RCU to prevent the keyring lists from disappearing on us |
1da177e4 LT |
278 | * - we return -EAGAIN if we didn't find any matching key |
279 | * - we return -ENOKEY if we only found negative matching keys | |
664cceb0 | 280 | * - we propagate the possession attribute from the keyring ref to the key ref |
1da177e4 | 281 | */ |
664cceb0 DH |
282 | key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
283 | struct task_struct *context, | |
284 | struct key_type *type, | |
285 | const void *description, | |
286 | key_match_func_t match) | |
1da177e4 LT |
287 | { |
288 | struct { | |
76d8aeab | 289 | struct keyring_list *keylist; |
1da177e4 LT |
290 | int kix; |
291 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
292 | ||
293 | struct keyring_list *keylist; | |
294 | struct timespec now; | |
dceba994 | 295 | unsigned long possessed, kflags; |
664cceb0 DH |
296 | struct key *keyring, *key; |
297 | key_ref_t key_ref; | |
1da177e4 | 298 | long err; |
76d8aeab | 299 | int sp, kix; |
1da177e4 | 300 | |
664cceb0 DH |
301 | keyring = key_ref_to_ptr(keyring_ref); |
302 | possessed = is_key_possessed(keyring_ref); | |
1da177e4 LT |
303 | key_check(keyring); |
304 | ||
305 | /* top keyring must have search permission to begin the search */ | |
29db9190 DH |
306 | err = key_task_permission(keyring_ref, context, KEY_SEARCH); |
307 | if (err < 0) { | |
308 | key_ref = ERR_PTR(err); | |
1da177e4 | 309 | goto error; |
29db9190 | 310 | } |
1da177e4 | 311 | |
664cceb0 | 312 | key_ref = ERR_PTR(-ENOTDIR); |
1da177e4 LT |
313 | if (keyring->type != &key_type_keyring) |
314 | goto error; | |
315 | ||
664cceb0 DH |
316 | rcu_read_lock(); |
317 | ||
1da177e4 LT |
318 | now = current_kernel_time(); |
319 | err = -EAGAIN; | |
320 | sp = 0; | |
321 | ||
dceba994 KC |
322 | /* firstly we should check to see if this top-level keyring is what we |
323 | * are looking for */ | |
324 | key_ref = ERR_PTR(-EAGAIN); | |
325 | kflags = keyring->flags; | |
326 | if (keyring->type == type && match(keyring, description)) { | |
327 | key = keyring; | |
328 | ||
329 | /* check it isn't negative and hasn't expired or been | |
330 | * revoked */ | |
331 | if (kflags & (1 << KEY_FLAG_REVOKED)) | |
332 | goto error_2; | |
333 | if (key->expiry && now.tv_sec >= key->expiry) | |
334 | goto error_2; | |
335 | key_ref = ERR_PTR(-ENOKEY); | |
336 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) | |
337 | goto error_2; | |
338 | goto found; | |
339 | } | |
340 | ||
341 | /* otherwise, the top keyring must not be revoked, expired, or | |
342 | * negatively instantiated if we are to search it */ | |
343 | key_ref = ERR_PTR(-EAGAIN); | |
344 | if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) || | |
345 | (keyring->expiry && now.tv_sec >= keyring->expiry)) | |
346 | goto error_2; | |
347 | ||
1da177e4 | 348 | /* start processing a new keyring */ |
664cceb0 | 349 | descend: |
76d8aeab | 350 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
351 | goto not_this_keyring; |
352 | ||
76d8aeab | 353 | keylist = rcu_dereference(keyring->payload.subscriptions); |
1da177e4 LT |
354 | if (!keylist) |
355 | goto not_this_keyring; | |
356 | ||
357 | /* iterate through the keys in this keyring first */ | |
358 | for (kix = 0; kix < keylist->nkeys; kix++) { | |
359 | key = keylist->keys[kix]; | |
dceba994 | 360 | kflags = key->flags; |
1da177e4 LT |
361 | |
362 | /* ignore keys not of this type */ | |
363 | if (key->type != type) | |
364 | continue; | |
365 | ||
366 | /* skip revoked keys and expired keys */ | |
dceba994 | 367 | if (kflags & (1 << KEY_FLAG_REVOKED)) |
1da177e4 LT |
368 | continue; |
369 | ||
370 | if (key->expiry && now.tv_sec >= key->expiry) | |
371 | continue; | |
372 | ||
373 | /* keys that don't match */ | |
374 | if (!match(key, description)) | |
375 | continue; | |
376 | ||
377 | /* key must have search permissions */ | |
29db9190 DH |
378 | if (key_task_permission(make_key_ref(key, possessed), |
379 | context, KEY_SEARCH) < 0) | |
1da177e4 LT |
380 | continue; |
381 | ||
dceba994 KC |
382 | /* we set a different error code if we pass a negative key */ |
383 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) { | |
1da177e4 LT |
384 | err = -ENOKEY; |
385 | continue; | |
386 | } | |
387 | ||
388 | goto found; | |
389 | } | |
390 | ||
391 | /* search through the keyrings nested in this one */ | |
392 | kix = 0; | |
664cceb0 | 393 | ascend: |
76d8aeab | 394 | for (; kix < keylist->nkeys; kix++) { |
1da177e4 LT |
395 | key = keylist->keys[kix]; |
396 | if (key->type != &key_type_keyring) | |
76d8aeab | 397 | continue; |
1da177e4 LT |
398 | |
399 | /* recursively search nested keyrings | |
400 | * - only search keyrings for which we have search permission | |
401 | */ | |
402 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
76d8aeab | 403 | continue; |
1da177e4 | 404 | |
0f6ed7c2 DH |
405 | if (key_task_permission(make_key_ref(key, possessed), |
406 | context, KEY_SEARCH) < 0) | |
76d8aeab | 407 | continue; |
1da177e4 LT |
408 | |
409 | /* stack the current position */ | |
76d8aeab | 410 | stack[sp].keylist = keylist; |
1da177e4 LT |
411 | stack[sp].kix = kix; |
412 | sp++; | |
413 | ||
414 | /* begin again with the new keyring */ | |
415 | keyring = key; | |
416 | goto descend; | |
1da177e4 LT |
417 | } |
418 | ||
419 | /* the keyring we're looking at was disqualified or didn't contain a | |
420 | * matching key */ | |
664cceb0 | 421 | not_this_keyring: |
1da177e4 LT |
422 | if (sp > 0) { |
423 | /* resume the processing of a keyring higher up in the tree */ | |
424 | sp--; | |
76d8aeab | 425 | keylist = stack[sp].keylist; |
1da177e4 LT |
426 | kix = stack[sp].kix + 1; |
427 | goto ascend; | |
428 | } | |
429 | ||
664cceb0 DH |
430 | key_ref = ERR_PTR(err); |
431 | goto error_2; | |
1da177e4 LT |
432 | |
433 | /* we found a viable match */ | |
664cceb0 | 434 | found: |
1da177e4 | 435 | atomic_inc(&key->usage); |
1da177e4 | 436 | key_check(key); |
664cceb0 DH |
437 | key_ref = make_key_ref(key, possessed); |
438 | error_2: | |
76d8aeab | 439 | rcu_read_unlock(); |
664cceb0 DH |
440 | error: |
441 | return key_ref; | |
1da177e4 LT |
442 | |
443 | } /* end keyring_search_aux() */ | |
444 | ||
445 | /*****************************************************************************/ | |
446 | /* | |
447 | * search the supplied keyring tree for a key that matches the criterion | |
448 | * - perform a breadth-then-depth search up to the prescribed limit | |
449 | * - we only find keys on which we have search permission | |
450 | * - we readlock the keyrings as we search down the tree | |
451 | * - we return -EAGAIN if we didn't find any matching key | |
452 | * - we return -ENOKEY if we only found negative matching keys | |
453 | */ | |
664cceb0 DH |
454 | key_ref_t keyring_search(key_ref_t keyring, |
455 | struct key_type *type, | |
456 | const char *description) | |
1da177e4 | 457 | { |
3e30148c DH |
458 | if (!type->match) |
459 | return ERR_PTR(-ENOKEY); | |
460 | ||
461 | return keyring_search_aux(keyring, current, | |
462 | type, description, type->match); | |
1da177e4 LT |
463 | |
464 | } /* end keyring_search() */ | |
465 | ||
466 | EXPORT_SYMBOL(keyring_search); | |
467 | ||
468 | /*****************************************************************************/ | |
469 | /* | |
470 | * search the given keyring only (no recursion) | |
471 | * - keyring must be locked by caller | |
c3a9d654 | 472 | * - caller must guarantee that the keyring is a keyring |
1da177e4 | 473 | */ |
664cceb0 DH |
474 | key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
475 | const struct key_type *ktype, | |
476 | const char *description, | |
477 | key_perm_t perm) | |
1da177e4 LT |
478 | { |
479 | struct keyring_list *klist; | |
664cceb0 DH |
480 | unsigned long possessed; |
481 | struct key *keyring, *key; | |
1da177e4 LT |
482 | int loop; |
483 | ||
664cceb0 DH |
484 | keyring = key_ref_to_ptr(keyring_ref); |
485 | possessed = is_key_possessed(keyring_ref); | |
486 | ||
76d8aeab DH |
487 | rcu_read_lock(); |
488 | ||
489 | klist = rcu_dereference(keyring->payload.subscriptions); | |
1da177e4 LT |
490 | if (klist) { |
491 | for (loop = 0; loop < klist->nkeys; loop++) { | |
492 | key = klist->keys[loop]; | |
493 | ||
494 | if (key->type == ktype && | |
3e30148c DH |
495 | (!key->type->match || |
496 | key->type->match(key, description)) && | |
664cceb0 | 497 | key_permission(make_key_ref(key, possessed), |
db1d1d57 | 498 | perm) == 0 && |
76d8aeab | 499 | !test_bit(KEY_FLAG_REVOKED, &key->flags) |
1da177e4 LT |
500 | ) |
501 | goto found; | |
502 | } | |
503 | } | |
504 | ||
664cceb0 DH |
505 | rcu_read_unlock(); |
506 | return ERR_PTR(-ENOKEY); | |
1da177e4 LT |
507 | |
508 | found: | |
509 | atomic_inc(&key->usage); | |
76d8aeab | 510 | rcu_read_unlock(); |
664cceb0 | 511 | return make_key_ref(key, possessed); |
1da177e4 LT |
512 | |
513 | } /* end __keyring_search_one() */ | |
514 | ||
515 | /*****************************************************************************/ | |
516 | /* | |
517 | * find a keyring with the specified name | |
518 | * - all named keyrings are searched | |
519 | * - only find keyrings with search permission for the process | |
520 | * - only find keyrings with a serial number greater than the one specified | |
521 | */ | |
522 | struct key *find_keyring_by_name(const char *name, key_serial_t bound) | |
523 | { | |
524 | struct key *keyring; | |
525 | int bucket; | |
526 | ||
527 | keyring = ERR_PTR(-EINVAL); | |
528 | if (!name) | |
529 | goto error; | |
530 | ||
531 | bucket = keyring_hash(name); | |
532 | ||
533 | read_lock(&keyring_name_lock); | |
534 | ||
535 | if (keyring_name_hash[bucket].next) { | |
536 | /* search this hash bucket for a keyring with a matching name | |
537 | * that's readable and that hasn't been revoked */ | |
538 | list_for_each_entry(keyring, | |
539 | &keyring_name_hash[bucket], | |
540 | type_data.link | |
541 | ) { | |
76d8aeab | 542 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
543 | continue; |
544 | ||
545 | if (strcmp(keyring->description, name) != 0) | |
546 | continue; | |
547 | ||
0f6ed7c2 DH |
548 | if (key_permission(make_key_ref(keyring, 0), |
549 | KEY_SEARCH) < 0) | |
1da177e4 LT |
550 | continue; |
551 | ||
552 | /* found a potential candidate, but we still need to | |
553 | * check the serial number */ | |
554 | if (keyring->serial <= bound) | |
555 | continue; | |
556 | ||
557 | /* we've got a match */ | |
558 | atomic_inc(&keyring->usage); | |
559 | read_unlock(&keyring_name_lock); | |
560 | goto error; | |
561 | } | |
562 | } | |
563 | ||
564 | read_unlock(&keyring_name_lock); | |
565 | keyring = ERR_PTR(-ENOKEY); | |
566 | ||
567 | error: | |
568 | return keyring; | |
569 | ||
570 | } /* end find_keyring_by_name() */ | |
571 | ||
572 | /*****************************************************************************/ | |
573 | /* | |
574 | * see if a cycle will will be created by inserting acyclic tree B in acyclic | |
575 | * tree A at the topmost level (ie: as a direct child of A) | |
576 | * - since we are adding B to A at the top level, checking for cycles should | |
577 | * just be a matter of seeing if node A is somewhere in tree B | |
578 | */ | |
579 | static int keyring_detect_cycle(struct key *A, struct key *B) | |
580 | { | |
581 | struct { | |
76d8aeab | 582 | struct keyring_list *keylist; |
1da177e4 LT |
583 | int kix; |
584 | } stack[KEYRING_SEARCH_MAX_DEPTH]; | |
585 | ||
586 | struct keyring_list *keylist; | |
587 | struct key *subtree, *key; | |
588 | int sp, kix, ret; | |
589 | ||
76d8aeab DH |
590 | rcu_read_lock(); |
591 | ||
1da177e4 LT |
592 | ret = -EDEADLK; |
593 | if (A == B) | |
76d8aeab | 594 | goto cycle_detected; |
1da177e4 LT |
595 | |
596 | subtree = B; | |
597 | sp = 0; | |
598 | ||
599 | /* start processing a new keyring */ | |
600 | descend: | |
76d8aeab | 601 | if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
1da177e4 LT |
602 | goto not_this_keyring; |
603 | ||
76d8aeab | 604 | keylist = rcu_dereference(subtree->payload.subscriptions); |
1da177e4 LT |
605 | if (!keylist) |
606 | goto not_this_keyring; | |
607 | kix = 0; | |
608 | ||
609 | ascend: | |
610 | /* iterate through the remaining keys in this keyring */ | |
611 | for (; kix < keylist->nkeys; kix++) { | |
612 | key = keylist->keys[kix]; | |
613 | ||
614 | if (key == A) | |
615 | goto cycle_detected; | |
616 | ||
617 | /* recursively check nested keyrings */ | |
618 | if (key->type == &key_type_keyring) { | |
619 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) | |
620 | goto too_deep; | |
621 | ||
622 | /* stack the current position */ | |
76d8aeab | 623 | stack[sp].keylist = keylist; |
1da177e4 LT |
624 | stack[sp].kix = kix; |
625 | sp++; | |
626 | ||
627 | /* begin again with the new keyring */ | |
628 | subtree = key; | |
629 | goto descend; | |
630 | } | |
631 | } | |
632 | ||
633 | /* the keyring we're looking at was disqualified or didn't contain a | |
634 | * matching key */ | |
635 | not_this_keyring: | |
1da177e4 LT |
636 | if (sp > 0) { |
637 | /* resume the checking of a keyring higher up in the tree */ | |
638 | sp--; | |
76d8aeab | 639 | keylist = stack[sp].keylist; |
1da177e4 LT |
640 | kix = stack[sp].kix + 1; |
641 | goto ascend; | |
642 | } | |
643 | ||
644 | ret = 0; /* no cycles detected */ | |
645 | ||
646 | error: | |
76d8aeab | 647 | rcu_read_unlock(); |
1da177e4 LT |
648 | return ret; |
649 | ||
650 | too_deep: | |
651 | ret = -ELOOP; | |
76d8aeab DH |
652 | goto error; |
653 | ||
1da177e4 LT |
654 | cycle_detected: |
655 | ret = -EDEADLK; | |
1da177e4 LT |
656 | goto error; |
657 | ||
658 | } /* end keyring_detect_cycle() */ | |
659 | ||
76d8aeab DH |
660 | /*****************************************************************************/ |
661 | /* | |
662 | * dispose of a keyring list after the RCU grace period | |
663 | */ | |
664 | static void keyring_link_rcu_disposal(struct rcu_head *rcu) | |
665 | { | |
666 | struct keyring_list *klist = | |
667 | container_of(rcu, struct keyring_list, rcu); | |
668 | ||
669 | kfree(klist); | |
670 | ||
671 | } /* end keyring_link_rcu_disposal() */ | |
672 | ||
cab8eb59 DH |
673 | /*****************************************************************************/ |
674 | /* | |
675 | * dispose of a keyring list after the RCU grace period, freeing the unlinked | |
676 | * key | |
677 | */ | |
678 | static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) | |
679 | { | |
680 | struct keyring_list *klist = | |
681 | container_of(rcu, struct keyring_list, rcu); | |
682 | ||
683 | key_put(klist->keys[klist->delkey]); | |
684 | kfree(klist); | |
685 | ||
686 | } /* end keyring_unlink_rcu_disposal() */ | |
687 | ||
1da177e4 LT |
688 | /*****************************************************************************/ |
689 | /* | |
690 | * link a key into to a keyring | |
76d8aeab | 691 | * - must be called with the keyring's semaphore write-locked |
cab8eb59 | 692 | * - discard already extant link to matching key if there is one |
1da177e4 LT |
693 | */ |
694 | int __key_link(struct key *keyring, struct key *key) | |
695 | { | |
696 | struct keyring_list *klist, *nklist; | |
697 | unsigned max; | |
698 | size_t size; | |
cab8eb59 | 699 | int loop, ret; |
1da177e4 LT |
700 | |
701 | ret = -EKEYREVOKED; | |
76d8aeab | 702 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
1da177e4 LT |
703 | goto error; |
704 | ||
705 | ret = -ENOTDIR; | |
706 | if (keyring->type != &key_type_keyring) | |
707 | goto error; | |
708 | ||
709 | /* serialise link/link calls to prevent parallel calls causing a | |
710 | * cycle when applied to two keyring in opposite orders */ | |
711 | down_write(&keyring_serialise_link_sem); | |
712 | ||
713 | /* check that we aren't going to create a cycle adding one keyring to | |
714 | * another */ | |
715 | if (key->type == &key_type_keyring) { | |
716 | ret = keyring_detect_cycle(keyring, key); | |
717 | if (ret < 0) | |
718 | goto error2; | |
719 | } | |
720 | ||
cab8eb59 DH |
721 | /* see if there's a matching key we can displace */ |
722 | klist = keyring->payload.subscriptions; | |
723 | ||
724 | if (klist && klist->nkeys > 0) { | |
725 | struct key_type *type = key->type; | |
726 | ||
727 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { | |
728 | if (klist->keys[loop]->type == type && | |
729 | strcmp(klist->keys[loop]->description, | |
730 | key->description) == 0 | |
731 | ) { | |
732 | /* found a match - replace with new key */ | |
733 | size = sizeof(struct key *) * klist->maxkeys; | |
734 | size += sizeof(*klist); | |
735 | BUG_ON(size > PAGE_SIZE); | |
736 | ||
737 | ret = -ENOMEM; | |
48ad504e | 738 | nklist = kmemdup(klist, size, GFP_KERNEL); |
cab8eb59 DH |
739 | if (!nklist) |
740 | goto error2; | |
741 | ||
cab8eb59 DH |
742 | /* replace matched key */ |
743 | atomic_inc(&key->usage); | |
744 | nklist->keys[loop] = key; | |
745 | ||
746 | rcu_assign_pointer( | |
747 | keyring->payload.subscriptions, | |
748 | nklist); | |
749 | ||
750 | /* dispose of the old keyring list and the | |
751 | * displaced key */ | |
752 | klist->delkey = loop; | |
753 | call_rcu(&klist->rcu, | |
754 | keyring_unlink_rcu_disposal); | |
755 | ||
756 | goto done; | |
757 | } | |
758 | } | |
759 | } | |
760 | ||
1da177e4 LT |
761 | /* check that we aren't going to overrun the user's quota */ |
762 | ret = key_payload_reserve(keyring, | |
763 | keyring->datalen + KEYQUOTA_LINK_BYTES); | |
764 | if (ret < 0) | |
765 | goto error2; | |
766 | ||
767 | klist = keyring->payload.subscriptions; | |
768 | ||
769 | if (klist && klist->nkeys < klist->maxkeys) { | |
770 | /* there's sufficient slack space to add directly */ | |
771 | atomic_inc(&key->usage); | |
772 | ||
76d8aeab DH |
773 | klist->keys[klist->nkeys] = key; |
774 | smp_wmb(); | |
775 | klist->nkeys++; | |
776 | smp_wmb(); | |
1da177e4 LT |
777 | } |
778 | else { | |
779 | /* grow the key list */ | |
780 | max = 4; | |
781 | if (klist) | |
782 | max += klist->maxkeys; | |
783 | ||
784 | ret = -ENFILE; | |
76d8aeab DH |
785 | if (max > 65535) |
786 | goto error3; | |
a4014d8f | 787 | size = sizeof(*klist) + sizeof(struct key *) * max; |
1da177e4 LT |
788 | if (size > PAGE_SIZE) |
789 | goto error3; | |
790 | ||
791 | ret = -ENOMEM; | |
792 | nklist = kmalloc(size, GFP_KERNEL); | |
793 | if (!nklist) | |
794 | goto error3; | |
795 | nklist->maxkeys = max; | |
796 | nklist->nkeys = 0; | |
797 | ||
798 | if (klist) { | |
799 | nklist->nkeys = klist->nkeys; | |
800 | memcpy(nklist->keys, | |
801 | klist->keys, | |
802 | sizeof(struct key *) * klist->nkeys); | |
803 | } | |
804 | ||
805 | /* add the key into the new space */ | |
806 | atomic_inc(&key->usage); | |
1da177e4 | 807 | nklist->keys[nklist->nkeys++] = key; |
76d8aeab DH |
808 | |
809 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); | |
1da177e4 LT |
810 | |
811 | /* dispose of the old keyring list */ | |
76d8aeab DH |
812 | if (klist) |
813 | call_rcu(&klist->rcu, keyring_link_rcu_disposal); | |
1da177e4 LT |
814 | } |
815 | ||
cab8eb59 DH |
816 | done: |
817 | ret = 0; | |
818 | error2: | |
1da177e4 | 819 | up_write(&keyring_serialise_link_sem); |
cab8eb59 | 820 | error: |
1da177e4 LT |
821 | return ret; |
822 | ||
cab8eb59 | 823 | error3: |
1da177e4 LT |
824 | /* undo the quota changes */ |
825 | key_payload_reserve(keyring, | |
826 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
827 | goto error2; | |
828 | ||
829 | } /* end __key_link() */ | |
830 | ||
831 | /*****************************************************************************/ | |
832 | /* | |
833 | * link a key to a keyring | |
834 | */ | |
835 | int key_link(struct key *keyring, struct key *key) | |
836 | { | |
837 | int ret; | |
838 | ||
839 | key_check(keyring); | |
840 | key_check(key); | |
841 | ||
842 | down_write(&keyring->sem); | |
843 | ret = __key_link(keyring, key); | |
844 | up_write(&keyring->sem); | |
845 | ||
846 | return ret; | |
847 | ||
848 | } /* end key_link() */ | |
849 | ||
850 | EXPORT_SYMBOL(key_link); | |
851 | ||
852 | /*****************************************************************************/ | |
853 | /* | |
854 | * unlink the first link to a key from a keyring | |
855 | */ | |
856 | int key_unlink(struct key *keyring, struct key *key) | |
857 | { | |
76d8aeab | 858 | struct keyring_list *klist, *nklist; |
1da177e4 LT |
859 | int loop, ret; |
860 | ||
861 | key_check(keyring); | |
862 | key_check(key); | |
863 | ||
864 | ret = -ENOTDIR; | |
865 | if (keyring->type != &key_type_keyring) | |
866 | goto error; | |
867 | ||
868 | down_write(&keyring->sem); | |
869 | ||
870 | klist = keyring->payload.subscriptions; | |
871 | if (klist) { | |
872 | /* search the keyring for the key */ | |
873 | for (loop = 0; loop < klist->nkeys; loop++) | |
874 | if (klist->keys[loop] == key) | |
875 | goto key_is_present; | |
876 | } | |
877 | ||
878 | up_write(&keyring->sem); | |
879 | ret = -ENOENT; | |
880 | goto error; | |
881 | ||
76d8aeab DH |
882 | key_is_present: |
883 | /* we need to copy the key list for RCU purposes */ | |
a4014d8f DH |
884 | nklist = kmalloc(sizeof(*klist) + |
885 | sizeof(struct key *) * klist->maxkeys, | |
76d8aeab DH |
886 | GFP_KERNEL); |
887 | if (!nklist) | |
888 | goto nomem; | |
889 | nklist->maxkeys = klist->maxkeys; | |
890 | nklist->nkeys = klist->nkeys - 1; | |
891 | ||
892 | if (loop > 0) | |
893 | memcpy(&nklist->keys[0], | |
894 | &klist->keys[0], | |
a4014d8f | 895 | loop * sizeof(struct key *)); |
76d8aeab DH |
896 | |
897 | if (loop < nklist->nkeys) | |
898 | memcpy(&nklist->keys[loop], | |
899 | &klist->keys[loop + 1], | |
a4014d8f | 900 | (nklist->nkeys - loop) * sizeof(struct key *)); |
76d8aeab | 901 | |
1da177e4 LT |
902 | /* adjust the user's quota */ |
903 | key_payload_reserve(keyring, | |
904 | keyring->datalen - KEYQUOTA_LINK_BYTES); | |
905 | ||
76d8aeab | 906 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
1da177e4 | 907 | |
76d8aeab | 908 | up_write(&keyring->sem); |
1da177e4 | 909 | |
76d8aeab DH |
910 | /* schedule for later cleanup */ |
911 | klist->delkey = loop; | |
912 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); | |
1da177e4 | 913 | |
1da177e4 LT |
914 | ret = 0; |
915 | ||
76d8aeab | 916 | error: |
1da177e4 | 917 | return ret; |
76d8aeab DH |
918 | nomem: |
919 | ret = -ENOMEM; | |
920 | up_write(&keyring->sem); | |
921 | goto error; | |
1da177e4 LT |
922 | |
923 | } /* end key_unlink() */ | |
924 | ||
925 | EXPORT_SYMBOL(key_unlink); | |
926 | ||
76d8aeab DH |
927 | /*****************************************************************************/ |
928 | /* | |
929 | * dispose of a keyring list after the RCU grace period, releasing the keys it | |
930 | * links to | |
931 | */ | |
932 | static void keyring_clear_rcu_disposal(struct rcu_head *rcu) | |
933 | { | |
934 | struct keyring_list *klist; | |
935 | int loop; | |
936 | ||
937 | klist = container_of(rcu, struct keyring_list, rcu); | |
938 | ||
939 | for (loop = klist->nkeys - 1; loop >= 0; loop--) | |
940 | key_put(klist->keys[loop]); | |
941 | ||
942 | kfree(klist); | |
943 | ||
944 | } /* end keyring_clear_rcu_disposal() */ | |
945 | ||
1da177e4 LT |
946 | /*****************************************************************************/ |
947 | /* | |
948 | * clear the specified process keyring | |
949 | * - implements keyctl(KEYCTL_CLEAR) | |
950 | */ | |
951 | int keyring_clear(struct key *keyring) | |
952 | { | |
953 | struct keyring_list *klist; | |
76d8aeab | 954 | int ret; |
1da177e4 LT |
955 | |
956 | ret = -ENOTDIR; | |
957 | if (keyring->type == &key_type_keyring) { | |
958 | /* detach the pointer block with the locks held */ | |
959 | down_write(&keyring->sem); | |
960 | ||
961 | klist = keyring->payload.subscriptions; | |
962 | if (klist) { | |
963 | /* adjust the quota */ | |
964 | key_payload_reserve(keyring, | |
965 | sizeof(struct keyring_list)); | |
966 | ||
76d8aeab DH |
967 | rcu_assign_pointer(keyring->payload.subscriptions, |
968 | NULL); | |
1da177e4 LT |
969 | } |
970 | ||
971 | up_write(&keyring->sem); | |
972 | ||
973 | /* free the keys after the locks have been dropped */ | |
76d8aeab DH |
974 | if (klist) |
975 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1da177e4 LT |
976 | |
977 | ret = 0; | |
978 | } | |
979 | ||
980 | return ret; | |
981 | ||
982 | } /* end keyring_clear() */ | |
983 | ||
984 | EXPORT_SYMBOL(keyring_clear); | |
31204ed9 DH |
985 | |
986 | /*****************************************************************************/ | |
987 | /* | |
988 | * dispose of the links from a revoked keyring | |
989 | * - called with the key sem write-locked | |
990 | */ | |
991 | static void keyring_revoke(struct key *keyring) | |
992 | { | |
993 | struct keyring_list *klist = keyring->payload.subscriptions; | |
994 | ||
995 | /* adjust the quota */ | |
996 | key_payload_reserve(keyring, 0); | |
997 | ||
998 | if (klist) { | |
999 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); | |
1000 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); | |
1001 | } | |
1002 | ||
1003 | } /* end keyring_revoke() */ |