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1da177e4 LT |
1 | /* key.c: basic authentication token and access key management |
2 | * | |
3 | * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. | |
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> | |
16 | #include <linux/workqueue.h> | |
17 | #include <linux/err.h> | |
18 | #include "internal.h" | |
19 | ||
20 | static kmem_cache_t *key_jar; | |
21 | static key_serial_t key_serial_next = 3; | |
22 | struct rb_root key_serial_tree; /* tree of keys indexed by serial */ | |
23 | DEFINE_SPINLOCK(key_serial_lock); | |
24 | ||
25 | struct rb_root key_user_tree; /* tree of quota records indexed by UID */ | |
26 | DEFINE_SPINLOCK(key_user_lock); | |
27 | ||
28 | static LIST_HEAD(key_types_list); | |
29 | static DECLARE_RWSEM(key_types_sem); | |
30 | ||
31 | static void key_cleanup(void *data); | |
32 | static DECLARE_WORK(key_cleanup_task, key_cleanup, NULL); | |
33 | ||
34 | /* we serialise key instantiation and link */ | |
35 | DECLARE_RWSEM(key_construction_sem); | |
36 | ||
37 | /* any key who's type gets unegistered will be re-typed to this */ | |
38 | struct key_type key_type_dead = { | |
39 | .name = "dead", | |
40 | }; | |
41 | ||
42 | #ifdef KEY_DEBUGGING | |
43 | void __key_check(const struct key *key) | |
44 | { | |
45 | printk("__key_check: key %p {%08x} should be {%08x}\n", | |
46 | key, key->magic, KEY_DEBUG_MAGIC); | |
47 | BUG(); | |
48 | } | |
49 | #endif | |
50 | ||
51 | /*****************************************************************************/ | |
52 | /* | |
53 | * get the key quota record for a user, allocating a new record if one doesn't | |
54 | * already exist | |
55 | */ | |
56 | struct key_user *key_user_lookup(uid_t uid) | |
57 | { | |
58 | struct key_user *candidate = NULL, *user; | |
59 | struct rb_node *parent = NULL; | |
60 | struct rb_node **p; | |
61 | ||
62 | try_again: | |
63 | p = &key_user_tree.rb_node; | |
64 | spin_lock(&key_user_lock); | |
65 | ||
66 | /* search the tree for a user record with a matching UID */ | |
67 | while (*p) { | |
68 | parent = *p; | |
69 | user = rb_entry(parent, struct key_user, node); | |
70 | ||
71 | if (uid < user->uid) | |
72 | p = &(*p)->rb_left; | |
73 | else if (uid > user->uid) | |
74 | p = &(*p)->rb_right; | |
75 | else | |
76 | goto found; | |
77 | } | |
78 | ||
79 | /* if we get here, we failed to find a match in the tree */ | |
80 | if (!candidate) { | |
81 | /* allocate a candidate user record if we don't already have | |
82 | * one */ | |
83 | spin_unlock(&key_user_lock); | |
84 | ||
85 | user = NULL; | |
86 | candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL); | |
87 | if (unlikely(!candidate)) | |
88 | goto out; | |
89 | ||
90 | /* the allocation may have scheduled, so we need to repeat the | |
91 | * search lest someone else added the record whilst we were | |
92 | * asleep */ | |
93 | goto try_again; | |
94 | } | |
95 | ||
96 | /* if we get here, then the user record still hadn't appeared on the | |
97 | * second pass - so we use the candidate record */ | |
98 | atomic_set(&candidate->usage, 1); | |
99 | atomic_set(&candidate->nkeys, 0); | |
100 | atomic_set(&candidate->nikeys, 0); | |
101 | candidate->uid = uid; | |
102 | candidate->qnkeys = 0; | |
103 | candidate->qnbytes = 0; | |
104 | spin_lock_init(&candidate->lock); | |
105 | INIT_LIST_HEAD(&candidate->consq); | |
106 | ||
107 | rb_link_node(&candidate->node, parent, p); | |
108 | rb_insert_color(&candidate->node, &key_user_tree); | |
109 | spin_unlock(&key_user_lock); | |
110 | user = candidate; | |
111 | goto out; | |
112 | ||
113 | /* okay - we found a user record for this UID */ | |
114 | found: | |
115 | atomic_inc(&user->usage); | |
116 | spin_unlock(&key_user_lock); | |
117 | if (candidate) | |
118 | kfree(candidate); | |
119 | out: | |
120 | return user; | |
121 | ||
122 | } /* end key_user_lookup() */ | |
123 | ||
124 | /*****************************************************************************/ | |
125 | /* | |
126 | * dispose of a user structure | |
127 | */ | |
128 | void key_user_put(struct key_user *user) | |
129 | { | |
130 | if (atomic_dec_and_lock(&user->usage, &key_user_lock)) { | |
131 | rb_erase(&user->node, &key_user_tree); | |
132 | spin_unlock(&key_user_lock); | |
133 | ||
134 | kfree(user); | |
135 | } | |
136 | ||
137 | } /* end key_user_put() */ | |
138 | ||
139 | /*****************************************************************************/ | |
140 | /* | |
141 | * insert a key with a fixed serial number | |
142 | */ | |
143 | static void __init __key_insert_serial(struct key *key) | |
144 | { | |
145 | struct rb_node *parent, **p; | |
146 | struct key *xkey; | |
147 | ||
148 | parent = NULL; | |
149 | p = &key_serial_tree.rb_node; | |
150 | ||
151 | while (*p) { | |
152 | parent = *p; | |
153 | xkey = rb_entry(parent, struct key, serial_node); | |
154 | ||
155 | if (key->serial < xkey->serial) | |
156 | p = &(*p)->rb_left; | |
157 | else if (key->serial > xkey->serial) | |
158 | p = &(*p)->rb_right; | |
159 | else | |
160 | BUG(); | |
161 | } | |
162 | ||
163 | /* we've found a suitable hole - arrange for this key to occupy it */ | |
164 | rb_link_node(&key->serial_node, parent, p); | |
165 | rb_insert_color(&key->serial_node, &key_serial_tree); | |
166 | ||
167 | } /* end __key_insert_serial() */ | |
168 | ||
169 | /*****************************************************************************/ | |
170 | /* | |
171 | * assign a key the next unique serial number | |
172 | * - we work through all the serial numbers between 2 and 2^31-1 in turn and | |
173 | * then wrap | |
174 | */ | |
175 | static inline void key_alloc_serial(struct key *key) | |
176 | { | |
177 | struct rb_node *parent, **p; | |
178 | struct key *xkey; | |
179 | ||
180 | spin_lock(&key_serial_lock); | |
181 | ||
182 | /* propose a likely serial number and look for a hole for it in the | |
183 | * serial number tree */ | |
184 | key->serial = key_serial_next; | |
185 | if (key->serial < 3) | |
186 | key->serial = 3; | |
187 | key_serial_next = key->serial + 1; | |
188 | ||
189 | parent = NULL; | |
190 | p = &key_serial_tree.rb_node; | |
191 | ||
192 | while (*p) { | |
193 | parent = *p; | |
194 | xkey = rb_entry(parent, struct key, serial_node); | |
195 | ||
196 | if (key->serial < xkey->serial) | |
197 | p = &(*p)->rb_left; | |
198 | else if (key->serial > xkey->serial) | |
199 | p = &(*p)->rb_right; | |
200 | else | |
201 | goto serial_exists; | |
202 | } | |
203 | goto insert_here; | |
204 | ||
205 | /* we found a key with the proposed serial number - walk the tree from | |
206 | * that point looking for the next unused serial number */ | |
207 | serial_exists: | |
208 | for (;;) { | |
209 | key->serial = key_serial_next; | |
210 | if (key->serial < 2) | |
211 | key->serial = 2; | |
212 | key_serial_next = key->serial + 1; | |
213 | ||
214 | if (!parent->rb_parent) | |
215 | p = &key_serial_tree.rb_node; | |
216 | else if (parent->rb_parent->rb_left == parent) | |
217 | p = &parent->rb_parent->rb_left; | |
218 | else | |
219 | p = &parent->rb_parent->rb_right; | |
220 | ||
221 | parent = rb_next(parent); | |
222 | if (!parent) | |
223 | break; | |
224 | ||
225 | xkey = rb_entry(parent, struct key, serial_node); | |
226 | if (key->serial < xkey->serial) | |
227 | goto insert_here; | |
228 | } | |
229 | ||
230 | /* we've found a suitable hole - arrange for this key to occupy it */ | |
231 | insert_here: | |
232 | rb_link_node(&key->serial_node, parent, p); | |
233 | rb_insert_color(&key->serial_node, &key_serial_tree); | |
234 | ||
235 | spin_unlock(&key_serial_lock); | |
236 | ||
237 | } /* end key_alloc_serial() */ | |
238 | ||
239 | /*****************************************************************************/ | |
240 | /* | |
241 | * allocate a key of the specified type | |
242 | * - update the user's quota to reflect the existence of the key | |
243 | * - called from a key-type operation with key_types_sem read-locked by either | |
244 | * key_create_or_update() or by key_duplicate(); this prevents unregistration | |
245 | * of the key type | |
246 | * - upon return the key is as yet uninstantiated; the caller needs to either | |
247 | * instantiate the key or discard it before returning | |
248 | */ | |
249 | struct key *key_alloc(struct key_type *type, const char *desc, | |
250 | uid_t uid, gid_t gid, key_perm_t perm, | |
251 | int not_in_quota) | |
252 | { | |
253 | struct key_user *user = NULL; | |
254 | struct key *key; | |
255 | size_t desclen, quotalen; | |
256 | ||
257 | key = ERR_PTR(-EINVAL); | |
258 | if (!desc || !*desc) | |
259 | goto error; | |
260 | ||
261 | desclen = strlen(desc) + 1; | |
262 | quotalen = desclen + type->def_datalen; | |
263 | ||
264 | /* get hold of the key tracking for this user */ | |
265 | user = key_user_lookup(uid); | |
266 | if (!user) | |
267 | goto no_memory_1; | |
268 | ||
269 | /* check that the user's quota permits allocation of another key and | |
270 | * its description */ | |
271 | if (!not_in_quota) { | |
272 | spin_lock(&user->lock); | |
273 | if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS && | |
274 | user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES | |
275 | ) | |
276 | goto no_quota; | |
277 | ||
278 | user->qnkeys++; | |
279 | user->qnbytes += quotalen; | |
280 | spin_unlock(&user->lock); | |
281 | } | |
282 | ||
283 | /* allocate and initialise the key and its description */ | |
284 | key = kmem_cache_alloc(key_jar, SLAB_KERNEL); | |
285 | if (!key) | |
286 | goto no_memory_2; | |
287 | ||
288 | if (desc) { | |
289 | key->description = kmalloc(desclen, GFP_KERNEL); | |
290 | if (!key->description) | |
291 | goto no_memory_3; | |
292 | ||
293 | memcpy(key->description, desc, desclen); | |
294 | } | |
295 | ||
296 | atomic_set(&key->usage, 1); | |
297 | rwlock_init(&key->lock); | |
298 | init_rwsem(&key->sem); | |
299 | key->type = type; | |
300 | key->user = user; | |
301 | key->quotalen = quotalen; | |
302 | key->datalen = type->def_datalen; | |
303 | key->uid = uid; | |
304 | key->gid = gid; | |
305 | key->perm = perm; | |
306 | key->flags = 0; | |
307 | key->expiry = 0; | |
308 | key->payload.data = NULL; | |
309 | ||
310 | if (!not_in_quota) | |
311 | key->flags |= KEY_FLAG_IN_QUOTA; | |
312 | ||
313 | memset(&key->type_data, 0, sizeof(key->type_data)); | |
314 | ||
315 | #ifdef KEY_DEBUGGING | |
316 | key->magic = KEY_DEBUG_MAGIC; | |
317 | #endif | |
318 | ||
319 | /* publish the key by giving it a serial number */ | |
320 | atomic_inc(&user->nkeys); | |
321 | key_alloc_serial(key); | |
322 | ||
323 | error: | |
324 | return key; | |
325 | ||
326 | no_memory_3: | |
327 | kmem_cache_free(key_jar, key); | |
328 | no_memory_2: | |
329 | if (!not_in_quota) { | |
330 | spin_lock(&user->lock); | |
331 | user->qnkeys--; | |
332 | user->qnbytes -= quotalen; | |
333 | spin_unlock(&user->lock); | |
334 | } | |
335 | key_user_put(user); | |
336 | no_memory_1: | |
337 | key = ERR_PTR(-ENOMEM); | |
338 | goto error; | |
339 | ||
340 | no_quota: | |
341 | spin_unlock(&user->lock); | |
342 | key_user_put(user); | |
343 | key = ERR_PTR(-EDQUOT); | |
344 | goto error; | |
345 | ||
346 | } /* end key_alloc() */ | |
347 | ||
348 | EXPORT_SYMBOL(key_alloc); | |
349 | ||
350 | /*****************************************************************************/ | |
351 | /* | |
352 | * reserve an amount of quota for the key's payload | |
353 | */ | |
354 | int key_payload_reserve(struct key *key, size_t datalen) | |
355 | { | |
356 | int delta = (int) datalen - key->datalen; | |
357 | int ret = 0; | |
358 | ||
359 | key_check(key); | |
360 | ||
361 | /* contemplate the quota adjustment */ | |
362 | if (delta != 0 && key->flags & KEY_FLAG_IN_QUOTA) { | |
363 | spin_lock(&key->user->lock); | |
364 | ||
365 | if (delta > 0 && | |
366 | key->user->qnbytes + delta > KEYQUOTA_MAX_BYTES | |
367 | ) { | |
368 | ret = -EDQUOT; | |
369 | } | |
370 | else { | |
371 | key->user->qnbytes += delta; | |
372 | key->quotalen += delta; | |
373 | } | |
374 | spin_unlock(&key->user->lock); | |
375 | } | |
376 | ||
377 | /* change the recorded data length if that didn't generate an error */ | |
378 | if (ret == 0) | |
379 | key->datalen = datalen; | |
380 | ||
381 | return ret; | |
382 | ||
383 | } /* end key_payload_reserve() */ | |
384 | ||
385 | EXPORT_SYMBOL(key_payload_reserve); | |
386 | ||
387 | /*****************************************************************************/ | |
388 | /* | |
389 | * instantiate a key and link it into the target keyring atomically | |
390 | * - called with the target keyring's semaphore writelocked | |
391 | */ | |
392 | static int __key_instantiate_and_link(struct key *key, | |
393 | const void *data, | |
394 | size_t datalen, | |
395 | struct key *keyring) | |
396 | { | |
397 | int ret, awaken; | |
398 | ||
399 | key_check(key); | |
400 | key_check(keyring); | |
401 | ||
402 | awaken = 0; | |
403 | ret = -EBUSY; | |
404 | ||
405 | down_write(&key_construction_sem); | |
406 | ||
407 | /* can't instantiate twice */ | |
408 | if (!(key->flags & KEY_FLAG_INSTANTIATED)) { | |
409 | /* instantiate the key */ | |
410 | ret = key->type->instantiate(key, data, datalen); | |
411 | ||
412 | if (ret == 0) { | |
413 | /* mark the key as being instantiated */ | |
414 | write_lock(&key->lock); | |
415 | ||
416 | atomic_inc(&key->user->nikeys); | |
417 | key->flags |= KEY_FLAG_INSTANTIATED; | |
418 | ||
419 | if (key->flags & KEY_FLAG_USER_CONSTRUCT) { | |
420 | key->flags &= ~KEY_FLAG_USER_CONSTRUCT; | |
421 | awaken = 1; | |
422 | } | |
423 | ||
424 | write_unlock(&key->lock); | |
425 | ||
426 | /* and link it into the destination keyring */ | |
427 | if (keyring) | |
428 | ret = __key_link(keyring, key); | |
429 | } | |
430 | } | |
431 | ||
432 | up_write(&key_construction_sem); | |
433 | ||
434 | /* wake up anyone waiting for a key to be constructed */ | |
435 | if (awaken) | |
436 | wake_up_all(&request_key_conswq); | |
437 | ||
438 | return ret; | |
439 | ||
440 | } /* end __key_instantiate_and_link() */ | |
441 | ||
442 | /*****************************************************************************/ | |
443 | /* | |
444 | * instantiate a key and link it into the target keyring atomically | |
445 | */ | |
446 | int key_instantiate_and_link(struct key *key, | |
447 | const void *data, | |
448 | size_t datalen, | |
449 | struct key *keyring) | |
450 | { | |
451 | int ret; | |
452 | ||
453 | if (keyring) | |
454 | down_write(&keyring->sem); | |
455 | ||
456 | ret = __key_instantiate_and_link(key, data, datalen, keyring); | |
457 | ||
458 | if (keyring) | |
459 | up_write(&keyring->sem); | |
460 | ||
461 | return ret; | |
462 | } /* end key_instantiate_and_link() */ | |
463 | ||
464 | EXPORT_SYMBOL(key_instantiate_and_link); | |
465 | ||
466 | /*****************************************************************************/ | |
467 | /* | |
468 | * negatively instantiate a key and link it into the target keyring atomically | |
469 | */ | |
470 | int key_negate_and_link(struct key *key, | |
471 | unsigned timeout, | |
472 | struct key *keyring) | |
473 | { | |
474 | struct timespec now; | |
475 | int ret, awaken; | |
476 | ||
477 | key_check(key); | |
478 | key_check(keyring); | |
479 | ||
480 | awaken = 0; | |
481 | ret = -EBUSY; | |
482 | ||
483 | if (keyring) | |
484 | down_write(&keyring->sem); | |
485 | ||
486 | down_write(&key_construction_sem); | |
487 | ||
488 | /* can't instantiate twice */ | |
489 | if (!(key->flags & KEY_FLAG_INSTANTIATED)) { | |
490 | /* mark the key as being negatively instantiated */ | |
491 | write_lock(&key->lock); | |
492 | ||
493 | atomic_inc(&key->user->nikeys); | |
494 | key->flags |= KEY_FLAG_INSTANTIATED | KEY_FLAG_NEGATIVE; | |
495 | now = current_kernel_time(); | |
496 | key->expiry = now.tv_sec + timeout; | |
497 | ||
498 | if (key->flags & KEY_FLAG_USER_CONSTRUCT) { | |
499 | key->flags &= ~KEY_FLAG_USER_CONSTRUCT; | |
500 | awaken = 1; | |
501 | } | |
502 | ||
503 | write_unlock(&key->lock); | |
504 | ret = 0; | |
505 | ||
506 | /* and link it into the destination keyring */ | |
507 | if (keyring) | |
508 | ret = __key_link(keyring, key); | |
509 | } | |
510 | ||
511 | up_write(&key_construction_sem); | |
512 | ||
513 | if (keyring) | |
514 | up_write(&keyring->sem); | |
515 | ||
516 | /* wake up anyone waiting for a key to be constructed */ | |
517 | if (awaken) | |
518 | wake_up_all(&request_key_conswq); | |
519 | ||
520 | return ret; | |
521 | ||
522 | } /* end key_negate_and_link() */ | |
523 | ||
524 | EXPORT_SYMBOL(key_negate_and_link); | |
525 | ||
526 | /*****************************************************************************/ | |
527 | /* | |
528 | * do cleaning up in process context so that we don't have to disable | |
529 | * interrupts all over the place | |
530 | */ | |
531 | static void key_cleanup(void *data) | |
532 | { | |
533 | struct rb_node *_n; | |
534 | struct key *key; | |
535 | ||
536 | go_again: | |
537 | /* look for a dead key in the tree */ | |
538 | spin_lock(&key_serial_lock); | |
539 | ||
540 | for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) { | |
541 | key = rb_entry(_n, struct key, serial_node); | |
542 | ||
543 | if (atomic_read(&key->usage) == 0) | |
544 | goto found_dead_key; | |
545 | } | |
546 | ||
547 | spin_unlock(&key_serial_lock); | |
548 | return; | |
549 | ||
550 | found_dead_key: | |
551 | /* we found a dead key - once we've removed it from the tree, we can | |
552 | * drop the lock */ | |
553 | rb_erase(&key->serial_node, &key_serial_tree); | |
554 | spin_unlock(&key_serial_lock); | |
555 | ||
556 | /* deal with the user's key tracking and quota */ | |
557 | if (key->flags & KEY_FLAG_IN_QUOTA) { | |
558 | spin_lock(&key->user->lock); | |
559 | key->user->qnkeys--; | |
560 | key->user->qnbytes -= key->quotalen; | |
561 | spin_unlock(&key->user->lock); | |
562 | } | |
563 | ||
564 | atomic_dec(&key->user->nkeys); | |
565 | if (key->flags & KEY_FLAG_INSTANTIATED) | |
566 | atomic_dec(&key->user->nikeys); | |
567 | ||
568 | key_user_put(key->user); | |
569 | ||
570 | /* now throw away the key memory */ | |
571 | if (key->type->destroy) | |
572 | key->type->destroy(key); | |
573 | ||
574 | kfree(key->description); | |
575 | ||
576 | #ifdef KEY_DEBUGGING | |
577 | key->magic = KEY_DEBUG_MAGIC_X; | |
578 | #endif | |
579 | kmem_cache_free(key_jar, key); | |
580 | ||
581 | /* there may, of course, be more than one key to destroy */ | |
582 | goto go_again; | |
583 | ||
584 | } /* end key_cleanup() */ | |
585 | ||
586 | /*****************************************************************************/ | |
587 | /* | |
588 | * dispose of a reference to a key | |
589 | * - when all the references are gone, we schedule the cleanup task to come and | |
590 | * pull it out of the tree in definite process context | |
591 | */ | |
592 | void key_put(struct key *key) | |
593 | { | |
594 | if (key) { | |
595 | key_check(key); | |
596 | ||
597 | if (atomic_dec_and_test(&key->usage)) | |
598 | schedule_work(&key_cleanup_task); | |
599 | } | |
600 | ||
601 | } /* end key_put() */ | |
602 | ||
603 | EXPORT_SYMBOL(key_put); | |
604 | ||
605 | /*****************************************************************************/ | |
606 | /* | |
607 | * find a key by its serial number | |
608 | */ | |
609 | struct key *key_lookup(key_serial_t id) | |
610 | { | |
611 | struct rb_node *n; | |
612 | struct key *key; | |
613 | ||
614 | spin_lock(&key_serial_lock); | |
615 | ||
616 | /* search the tree for the specified key */ | |
617 | n = key_serial_tree.rb_node; | |
618 | while (n) { | |
619 | key = rb_entry(n, struct key, serial_node); | |
620 | ||
621 | if (id < key->serial) | |
622 | n = n->rb_left; | |
623 | else if (id > key->serial) | |
624 | n = n->rb_right; | |
625 | else | |
626 | goto found; | |
627 | } | |
628 | ||
629 | not_found: | |
630 | key = ERR_PTR(-ENOKEY); | |
631 | goto error; | |
632 | ||
633 | found: | |
634 | /* pretent doesn't exist if it's dead */ | |
635 | if (atomic_read(&key->usage) == 0 || | |
636 | (key->flags & KEY_FLAG_DEAD) || | |
637 | key->type == &key_type_dead) | |
638 | goto not_found; | |
639 | ||
640 | /* this races with key_put(), but that doesn't matter since key_put() | |
641 | * doesn't actually change the key | |
642 | */ | |
643 | atomic_inc(&key->usage); | |
644 | ||
645 | error: | |
646 | spin_unlock(&key_serial_lock); | |
647 | return key; | |
648 | ||
649 | } /* end key_lookup() */ | |
650 | ||
651 | /*****************************************************************************/ | |
652 | /* | |
653 | * find and lock the specified key type against removal | |
654 | * - we return with the sem readlocked | |
655 | */ | |
656 | struct key_type *key_type_lookup(const char *type) | |
657 | { | |
658 | struct key_type *ktype; | |
659 | ||
660 | down_read(&key_types_sem); | |
661 | ||
662 | /* look up the key type to see if it's one of the registered kernel | |
663 | * types */ | |
664 | list_for_each_entry(ktype, &key_types_list, link) { | |
665 | if (strcmp(ktype->name, type) == 0) | |
666 | goto found_kernel_type; | |
667 | } | |
668 | ||
669 | up_read(&key_types_sem); | |
670 | ktype = ERR_PTR(-ENOKEY); | |
671 | ||
672 | found_kernel_type: | |
673 | return ktype; | |
674 | ||
675 | } /* end key_type_lookup() */ | |
676 | ||
677 | /*****************************************************************************/ | |
678 | /* | |
679 | * unlock a key type | |
680 | */ | |
681 | void key_type_put(struct key_type *ktype) | |
682 | { | |
683 | up_read(&key_types_sem); | |
684 | ||
685 | } /* end key_type_put() */ | |
686 | ||
687 | /*****************************************************************************/ | |
688 | /* | |
689 | * attempt to update an existing key | |
690 | * - the key has an incremented refcount | |
691 | * - we need to put the key if we get an error | |
692 | */ | |
693 | static inline struct key *__key_update(struct key *key, const void *payload, | |
694 | size_t plen) | |
695 | { | |
696 | int ret; | |
697 | ||
698 | /* need write permission on the key to update it */ | |
699 | ret = -EACCES; | |
700 | if (!key_permission(key, KEY_WRITE)) | |
701 | goto error; | |
702 | ||
703 | ret = -EEXIST; | |
704 | if (!key->type->update) | |
705 | goto error; | |
706 | ||
707 | down_write(&key->sem); | |
708 | ||
709 | ret = key->type->update(key, payload, plen); | |
710 | ||
711 | if (ret == 0) { | |
712 | /* updating a negative key instantiates it */ | |
713 | write_lock(&key->lock); | |
714 | key->flags &= ~KEY_FLAG_NEGATIVE; | |
715 | write_unlock(&key->lock); | |
716 | } | |
717 | ||
718 | up_write(&key->sem); | |
719 | ||
720 | if (ret < 0) | |
721 | goto error; | |
722 | out: | |
723 | return key; | |
724 | ||
725 | error: | |
726 | key_put(key); | |
727 | key = ERR_PTR(ret); | |
728 | goto out; | |
729 | ||
730 | } /* end __key_update() */ | |
731 | ||
732 | /*****************************************************************************/ | |
733 | /* | |
734 | * search the specified keyring for a key of the same description; if one is | |
735 | * found, update it, otherwise add a new one | |
736 | */ | |
737 | struct key *key_create_or_update(struct key *keyring, | |
738 | const char *type, | |
739 | const char *description, | |
740 | const void *payload, | |
741 | size_t plen, | |
742 | int not_in_quota) | |
743 | { | |
744 | struct key_type *ktype; | |
745 | struct key *key = NULL; | |
746 | key_perm_t perm; | |
747 | int ret; | |
748 | ||
749 | key_check(keyring); | |
750 | ||
751 | /* look up the key type to see if it's one of the registered kernel | |
752 | * types */ | |
753 | ktype = key_type_lookup(type); | |
754 | if (IS_ERR(ktype)) { | |
755 | key = ERR_PTR(-ENODEV); | |
756 | goto error; | |
757 | } | |
758 | ||
759 | ret = -EINVAL; | |
760 | if (!ktype->match || !ktype->instantiate) | |
761 | goto error_2; | |
762 | ||
763 | /* search for an existing key of the same type and description in the | |
764 | * destination keyring | |
765 | */ | |
766 | down_write(&keyring->sem); | |
767 | ||
768 | key = __keyring_search_one(keyring, ktype, description, 0); | |
769 | if (!IS_ERR(key)) | |
770 | goto found_matching_key; | |
771 | ||
772 | /* if we're going to allocate a new key, we're going to have to modify | |
773 | * the keyring */ | |
774 | ret = -EACCES; | |
775 | if (!key_permission(keyring, KEY_WRITE)) | |
776 | goto error_3; | |
777 | ||
778 | /* decide on the permissions we want */ | |
779 | perm = KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK; | |
780 | ||
781 | if (ktype->read) | |
782 | perm |= KEY_USR_READ; | |
783 | ||
784 | if (ktype == &key_type_keyring || ktype->update) | |
785 | perm |= KEY_USR_WRITE; | |
786 | ||
787 | /* allocate a new key */ | |
788 | key = key_alloc(ktype, description, current->fsuid, current->fsgid, | |
789 | perm, not_in_quota); | |
790 | if (IS_ERR(key)) { | |
791 | ret = PTR_ERR(key); | |
792 | goto error_3; | |
793 | } | |
794 | ||
795 | /* instantiate it and link it into the target keyring */ | |
796 | ret = __key_instantiate_and_link(key, payload, plen, keyring); | |
797 | if (ret < 0) { | |
798 | key_put(key); | |
799 | key = ERR_PTR(ret); | |
800 | } | |
801 | ||
802 | error_3: | |
803 | up_write(&keyring->sem); | |
804 | error_2: | |
805 | key_type_put(ktype); | |
806 | error: | |
807 | return key; | |
808 | ||
809 | found_matching_key: | |
810 | /* we found a matching key, so we're going to try to update it | |
811 | * - we can drop the locks first as we have the key pinned | |
812 | */ | |
813 | up_write(&keyring->sem); | |
814 | key_type_put(ktype); | |
815 | ||
816 | key = __key_update(key, payload, plen); | |
817 | goto error; | |
818 | ||
819 | } /* end key_create_or_update() */ | |
820 | ||
821 | EXPORT_SYMBOL(key_create_or_update); | |
822 | ||
823 | /*****************************************************************************/ | |
824 | /* | |
825 | * update a key | |
826 | */ | |
827 | int key_update(struct key *key, const void *payload, size_t plen) | |
828 | { | |
829 | int ret; | |
830 | ||
831 | key_check(key); | |
832 | ||
833 | /* the key must be writable */ | |
834 | ret = -EACCES; | |
835 | if (!key_permission(key, KEY_WRITE)) | |
836 | goto error; | |
837 | ||
838 | /* attempt to update it if supported */ | |
839 | ret = -EOPNOTSUPP; | |
840 | if (key->type->update) { | |
841 | down_write(&key->sem); | |
842 | ret = key->type->update(key, payload, plen); | |
843 | ||
844 | if (ret == 0) { | |
845 | /* updating a negative key instantiates it */ | |
846 | write_lock(&key->lock); | |
847 | key->flags &= ~KEY_FLAG_NEGATIVE; | |
848 | write_unlock(&key->lock); | |
849 | } | |
850 | ||
851 | up_write(&key->sem); | |
852 | } | |
853 | ||
854 | error: | |
855 | return ret; | |
856 | ||
857 | } /* end key_update() */ | |
858 | ||
859 | EXPORT_SYMBOL(key_update); | |
860 | ||
861 | /*****************************************************************************/ | |
862 | /* | |
863 | * duplicate a key, potentially with a revised description | |
864 | * - must be supported by the keytype (keyrings for instance can be duplicated) | |
865 | */ | |
866 | struct key *key_duplicate(struct key *source, const char *desc) | |
867 | { | |
868 | struct key *key; | |
869 | int ret; | |
870 | ||
871 | key_check(source); | |
872 | ||
873 | if (!desc) | |
874 | desc = source->description; | |
875 | ||
876 | down_read(&key_types_sem); | |
877 | ||
878 | ret = -EINVAL; | |
879 | if (!source->type->duplicate) | |
880 | goto error; | |
881 | ||
882 | /* allocate and instantiate a key */ | |
883 | key = key_alloc(source->type, desc, current->fsuid, current->fsgid, | |
884 | source->perm, 0); | |
885 | if (IS_ERR(key)) | |
886 | goto error_k; | |
887 | ||
888 | down_read(&source->sem); | |
889 | ret = key->type->duplicate(key, source); | |
890 | up_read(&source->sem); | |
891 | if (ret < 0) | |
892 | goto error2; | |
893 | ||
894 | atomic_inc(&key->user->nikeys); | |
895 | ||
896 | write_lock(&key->lock); | |
897 | key->flags |= KEY_FLAG_INSTANTIATED; | |
898 | write_unlock(&key->lock); | |
899 | ||
900 | error_k: | |
901 | up_read(&key_types_sem); | |
902 | out: | |
903 | return key; | |
904 | ||
905 | error2: | |
906 | key_put(key); | |
907 | error: | |
908 | up_read(&key_types_sem); | |
909 | key = ERR_PTR(ret); | |
910 | goto out; | |
911 | ||
912 | } /* end key_duplicate() */ | |
913 | ||
914 | /*****************************************************************************/ | |
915 | /* | |
916 | * revoke a key | |
917 | */ | |
918 | void key_revoke(struct key *key) | |
919 | { | |
920 | key_check(key); | |
921 | ||
922 | /* make sure no one's trying to change or use the key when we mark | |
923 | * it */ | |
924 | down_write(&key->sem); | |
925 | write_lock(&key->lock); | |
926 | key->flags |= KEY_FLAG_REVOKED; | |
927 | write_unlock(&key->lock); | |
928 | up_write(&key->sem); | |
929 | ||
930 | } /* end key_revoke() */ | |
931 | ||
932 | EXPORT_SYMBOL(key_revoke); | |
933 | ||
934 | /*****************************************************************************/ | |
935 | /* | |
936 | * register a type of key | |
937 | */ | |
938 | int register_key_type(struct key_type *ktype) | |
939 | { | |
940 | struct key_type *p; | |
941 | int ret; | |
942 | ||
943 | ret = -EEXIST; | |
944 | down_write(&key_types_sem); | |
945 | ||
946 | /* disallow key types with the same name */ | |
947 | list_for_each_entry(p, &key_types_list, link) { | |
948 | if (strcmp(p->name, ktype->name) == 0) | |
949 | goto out; | |
950 | } | |
951 | ||
952 | /* store the type */ | |
953 | list_add(&ktype->link, &key_types_list); | |
954 | ret = 0; | |
955 | ||
956 | out: | |
957 | up_write(&key_types_sem); | |
958 | return ret; | |
959 | ||
960 | } /* end register_key_type() */ | |
961 | ||
962 | EXPORT_SYMBOL(register_key_type); | |
963 | ||
964 | /*****************************************************************************/ | |
965 | /* | |
966 | * unregister a type of key | |
967 | */ | |
968 | void unregister_key_type(struct key_type *ktype) | |
969 | { | |
970 | struct rb_node *_n; | |
971 | struct key *key; | |
972 | ||
973 | down_write(&key_types_sem); | |
974 | ||
975 | /* withdraw the key type */ | |
976 | list_del_init(&ktype->link); | |
977 | ||
978 | /* need to withdraw all keys of this type */ | |
979 | spin_lock(&key_serial_lock); | |
980 | ||
981 | for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) { | |
982 | key = rb_entry(_n, struct key, serial_node); | |
983 | ||
984 | if (key->type != ktype) | |
985 | continue; | |
986 | ||
987 | write_lock(&key->lock); | |
988 | key->type = &key_type_dead; | |
989 | write_unlock(&key->lock); | |
990 | ||
991 | /* there shouldn't be anyone looking at the description or | |
992 | * payload now */ | |
993 | if (ktype->destroy) | |
994 | ktype->destroy(key); | |
995 | memset(&key->payload, 0xbd, sizeof(key->payload)); | |
996 | } | |
997 | ||
998 | spin_unlock(&key_serial_lock); | |
999 | up_write(&key_types_sem); | |
1000 | ||
1001 | } /* end unregister_key_type() */ | |
1002 | ||
1003 | EXPORT_SYMBOL(unregister_key_type); | |
1004 | ||
1005 | /*****************************************************************************/ | |
1006 | /* | |
1007 | * initialise the key management stuff | |
1008 | */ | |
1009 | void __init key_init(void) | |
1010 | { | |
1011 | /* allocate a slab in which we can store keys */ | |
1012 | key_jar = kmem_cache_create("key_jar", sizeof(struct key), | |
1013 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1014 | ||
1015 | /* add the special key types */ | |
1016 | list_add_tail(&key_type_keyring.link, &key_types_list); | |
1017 | list_add_tail(&key_type_dead.link, &key_types_list); | |
1018 | list_add_tail(&key_type_user.link, &key_types_list); | |
1019 | ||
1020 | /* record the root user tracking */ | |
1021 | rb_link_node(&root_key_user.node, | |
1022 | NULL, | |
1023 | &key_user_tree.rb_node); | |
1024 | ||
1025 | rb_insert_color(&root_key_user.node, | |
1026 | &key_user_tree); | |
1027 | ||
1028 | /* record root's user standard keyrings */ | |
1029 | key_check(&root_user_keyring); | |
1030 | key_check(&root_session_keyring); | |
1031 | ||
1032 | __key_insert_serial(&root_user_keyring); | |
1033 | __key_insert_serial(&root_session_keyring); | |
1034 | ||
1035 | keyring_publish_name(&root_user_keyring); | |
1036 | keyring_publish_name(&root_session_keyring); | |
1037 | ||
1038 | /* link the two root keyrings together */ | |
1039 | key_link(&root_session_keyring, &root_user_keyring); | |
1040 | } /* end key_init() */ |