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1 | /* Basic authentication token and access key management | |
2 | * | |
3 | * Copyright (C) 2004-2008 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/poison.h> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/security.h> | |
18 | #include <linux/workqueue.h> | |
19 | #include <linux/random.h> | |
20 | #include <linux/err.h> | |
21 | #include <linux/user_namespace.h> | |
22 | #include "internal.h" | |
23 | ||
24 | static struct kmem_cache *key_jar; | |
25 | struct rb_root key_serial_tree; /* tree of keys indexed by serial */ | |
26 | DEFINE_SPINLOCK(key_serial_lock); | |
27 | ||
28 | struct rb_root key_user_tree; /* tree of quota records indexed by UID */ | |
29 | DEFINE_SPINLOCK(key_user_lock); | |
30 | ||
31 | unsigned int key_quota_root_maxkeys = 200; /* root's key count quota */ | |
32 | unsigned int key_quota_root_maxbytes = 20000; /* root's key space quota */ | |
33 | unsigned int key_quota_maxkeys = 200; /* general key count quota */ | |
34 | unsigned int key_quota_maxbytes = 20000; /* general key space quota */ | |
35 | ||
36 | static LIST_HEAD(key_types_list); | |
37 | static DECLARE_RWSEM(key_types_sem); | |
38 | ||
39 | static void key_cleanup(struct work_struct *work); | |
40 | static DECLARE_WORK(key_cleanup_task, key_cleanup); | |
41 | ||
42 | /* we serialise key instantiation and link */ | |
43 | DEFINE_MUTEX(key_construction_mutex); | |
44 | ||
45 | /* any key who's type gets unegistered will be re-typed to this */ | |
46 | static struct key_type key_type_dead = { | |
47 | .name = "dead", | |
48 | }; | |
49 | ||
50 | #ifdef KEY_DEBUGGING | |
51 | void __key_check(const struct key *key) | |
52 | { | |
53 | printk("__key_check: key %p {%08x} should be {%08x}\n", | |
54 | key, key->magic, KEY_DEBUG_MAGIC); | |
55 | BUG(); | |
56 | } | |
57 | #endif | |
58 | ||
59 | /*****************************************************************************/ | |
60 | /* | |
61 | * get the key quota record for a user, allocating a new record if one doesn't | |
62 | * already exist | |
63 | */ | |
64 | struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns) | |
65 | { | |
66 | struct key_user *candidate = NULL, *user; | |
67 | struct rb_node *parent = NULL; | |
68 | struct rb_node **p; | |
69 | ||
70 | try_again: | |
71 | p = &key_user_tree.rb_node; | |
72 | spin_lock(&key_user_lock); | |
73 | ||
74 | /* search the tree for a user record with a matching UID */ | |
75 | while (*p) { | |
76 | parent = *p; | |
77 | user = rb_entry(parent, struct key_user, node); | |
78 | ||
79 | if (uid < user->uid) | |
80 | p = &(*p)->rb_left; | |
81 | else if (uid > user->uid) | |
82 | p = &(*p)->rb_right; | |
83 | else if (user_ns < user->user_ns) | |
84 | p = &(*p)->rb_left; | |
85 | else if (user_ns > user->user_ns) | |
86 | p = &(*p)->rb_right; | |
87 | else | |
88 | goto found; | |
89 | } | |
90 | ||
91 | /* if we get here, we failed to find a match in the tree */ | |
92 | if (!candidate) { | |
93 | /* allocate a candidate user record if we don't already have | |
94 | * one */ | |
95 | spin_unlock(&key_user_lock); | |
96 | ||
97 | user = NULL; | |
98 | candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL); | |
99 | if (unlikely(!candidate)) | |
100 | goto out; | |
101 | ||
102 | /* the allocation may have scheduled, so we need to repeat the | |
103 | * search lest someone else added the record whilst we were | |
104 | * asleep */ | |
105 | goto try_again; | |
106 | } | |
107 | ||
108 | /* if we get here, then the user record still hadn't appeared on the | |
109 | * second pass - so we use the candidate record */ | |
110 | atomic_set(&candidate->usage, 1); | |
111 | atomic_set(&candidate->nkeys, 0); | |
112 | atomic_set(&candidate->nikeys, 0); | |
113 | candidate->uid = uid; | |
114 | candidate->user_ns = get_user_ns(user_ns); | |
115 | candidate->qnkeys = 0; | |
116 | candidate->qnbytes = 0; | |
117 | spin_lock_init(&candidate->lock); | |
118 | mutex_init(&candidate->cons_lock); | |
119 | ||
120 | rb_link_node(&candidate->node, parent, p); | |
121 | rb_insert_color(&candidate->node, &key_user_tree); | |
122 | spin_unlock(&key_user_lock); | |
123 | user = candidate; | |
124 | goto out; | |
125 | ||
126 | /* okay - we found a user record for this UID */ | |
127 | found: | |
128 | atomic_inc(&user->usage); | |
129 | spin_unlock(&key_user_lock); | |
130 | kfree(candidate); | |
131 | out: | |
132 | return user; | |
133 | ||
134 | } /* end key_user_lookup() */ | |
135 | ||
136 | /*****************************************************************************/ | |
137 | /* | |
138 | * dispose of a user structure | |
139 | */ | |
140 | void key_user_put(struct key_user *user) | |
141 | { | |
142 | if (atomic_dec_and_lock(&user->usage, &key_user_lock)) { | |
143 | rb_erase(&user->node, &key_user_tree); | |
144 | spin_unlock(&key_user_lock); | |
145 | put_user_ns(user->user_ns); | |
146 | ||
147 | kfree(user); | |
148 | } | |
149 | ||
150 | } /* end key_user_put() */ | |
151 | ||
152 | /*****************************************************************************/ | |
153 | /* | |
154 | * assign a key the next unique serial number | |
155 | * - these are assigned randomly to avoid security issues through covert | |
156 | * channel problems | |
157 | */ | |
158 | static inline void key_alloc_serial(struct key *key) | |
159 | { | |
160 | struct rb_node *parent, **p; | |
161 | struct key *xkey; | |
162 | ||
163 | /* propose a random serial number and look for a hole for it in the | |
164 | * serial number tree */ | |
165 | do { | |
166 | get_random_bytes(&key->serial, sizeof(key->serial)); | |
167 | ||
168 | key->serial >>= 1; /* negative numbers are not permitted */ | |
169 | } while (key->serial < 3); | |
170 | ||
171 | spin_lock(&key_serial_lock); | |
172 | ||
173 | attempt_insertion: | |
174 | parent = NULL; | |
175 | p = &key_serial_tree.rb_node; | |
176 | ||
177 | while (*p) { | |
178 | parent = *p; | |
179 | xkey = rb_entry(parent, struct key, serial_node); | |
180 | ||
181 | if (key->serial < xkey->serial) | |
182 | p = &(*p)->rb_left; | |
183 | else if (key->serial > xkey->serial) | |
184 | p = &(*p)->rb_right; | |
185 | else | |
186 | goto serial_exists; | |
187 | } | |
188 | ||
189 | /* we've found a suitable hole - arrange for this key to occupy it */ | |
190 | rb_link_node(&key->serial_node, parent, p); | |
191 | rb_insert_color(&key->serial_node, &key_serial_tree); | |
192 | ||
193 | spin_unlock(&key_serial_lock); | |
194 | return; | |
195 | ||
196 | /* we found a key with the proposed serial number - walk the tree from | |
197 | * that point looking for the next unused serial number */ | |
198 | serial_exists: | |
199 | for (;;) { | |
200 | key->serial++; | |
201 | if (key->serial < 3) { | |
202 | key->serial = 3; | |
203 | goto attempt_insertion; | |
204 | } | |
205 | ||
206 | parent = rb_next(parent); | |
207 | if (!parent) | |
208 | goto attempt_insertion; | |
209 | ||
210 | xkey = rb_entry(parent, struct key, serial_node); | |
211 | if (key->serial < xkey->serial) | |
212 | goto attempt_insertion; | |
213 | } | |
214 | ||
215 | } /* end key_alloc_serial() */ | |
216 | ||
217 | /*****************************************************************************/ | |
218 | /* | |
219 | * allocate a key of the specified type | |
220 | * - update the user's quota to reflect the existence of the key | |
221 | * - called from a key-type operation with key_types_sem read-locked by | |
222 | * key_create_or_update() | |
223 | * - this prevents unregistration of the key type | |
224 | * - upon return the key is as yet uninstantiated; the caller needs to either | |
225 | * instantiate the key or discard it before returning | |
226 | */ | |
227 | struct key *key_alloc(struct key_type *type, const char *desc, | |
228 | uid_t uid, gid_t gid, const struct cred *cred, | |
229 | key_perm_t perm, unsigned long flags) | |
230 | { | |
231 | struct key_user *user = NULL; | |
232 | struct key *key; | |
233 | size_t desclen, quotalen; | |
234 | int ret; | |
235 | ||
236 | key = ERR_PTR(-EINVAL); | |
237 | if (!desc || !*desc) | |
238 | goto error; | |
239 | ||
240 | desclen = strlen(desc) + 1; | |
241 | quotalen = desclen + type->def_datalen; | |
242 | ||
243 | /* get hold of the key tracking for this user */ | |
244 | user = key_user_lookup(uid, cred->user->user_ns); | |
245 | if (!user) | |
246 | goto no_memory_1; | |
247 | ||
248 | /* check that the user's quota permits allocation of another key and | |
249 | * its description */ | |
250 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { | |
251 | unsigned maxkeys = (uid == 0) ? | |
252 | key_quota_root_maxkeys : key_quota_maxkeys; | |
253 | unsigned maxbytes = (uid == 0) ? | |
254 | key_quota_root_maxbytes : key_quota_maxbytes; | |
255 | ||
256 | spin_lock(&user->lock); | |
257 | if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) { | |
258 | if (user->qnkeys + 1 >= maxkeys || | |
259 | user->qnbytes + quotalen >= maxbytes || | |
260 | user->qnbytes + quotalen < user->qnbytes) | |
261 | goto no_quota; | |
262 | } | |
263 | ||
264 | user->qnkeys++; | |
265 | user->qnbytes += quotalen; | |
266 | spin_unlock(&user->lock); | |
267 | } | |
268 | ||
269 | /* allocate and initialise the key and its description */ | |
270 | key = kmem_cache_alloc(key_jar, GFP_KERNEL); | |
271 | if (!key) | |
272 | goto no_memory_2; | |
273 | ||
274 | if (desc) { | |
275 | key->description = kmemdup(desc, desclen, GFP_KERNEL); | |
276 | if (!key->description) | |
277 | goto no_memory_3; | |
278 | } | |
279 | ||
280 | atomic_set(&key->usage, 1); | |
281 | init_rwsem(&key->sem); | |
282 | key->type = type; | |
283 | key->user = user; | |
284 | key->quotalen = quotalen; | |
285 | key->datalen = type->def_datalen; | |
286 | key->uid = uid; | |
287 | key->gid = gid; | |
288 | key->perm = perm; | |
289 | key->flags = 0; | |
290 | key->expiry = 0; | |
291 | key->payload.data = NULL; | |
292 | key->security = NULL; | |
293 | ||
294 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) | |
295 | key->flags |= 1 << KEY_FLAG_IN_QUOTA; | |
296 | ||
297 | memset(&key->type_data, 0, sizeof(key->type_data)); | |
298 | ||
299 | #ifdef KEY_DEBUGGING | |
300 | key->magic = KEY_DEBUG_MAGIC; | |
301 | #endif | |
302 | ||
303 | /* let the security module know about the key */ | |
304 | ret = security_key_alloc(key, cred, flags); | |
305 | if (ret < 0) | |
306 | goto security_error; | |
307 | ||
308 | /* publish the key by giving it a serial number */ | |
309 | atomic_inc(&user->nkeys); | |
310 | key_alloc_serial(key); | |
311 | ||
312 | error: | |
313 | return key; | |
314 | ||
315 | security_error: | |
316 | kfree(key->description); | |
317 | kmem_cache_free(key_jar, key); | |
318 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { | |
319 | spin_lock(&user->lock); | |
320 | user->qnkeys--; | |
321 | user->qnbytes -= quotalen; | |
322 | spin_unlock(&user->lock); | |
323 | } | |
324 | key_user_put(user); | |
325 | key = ERR_PTR(ret); | |
326 | goto error; | |
327 | ||
328 | no_memory_3: | |
329 | kmem_cache_free(key_jar, key); | |
330 | no_memory_2: | |
331 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { | |
332 | spin_lock(&user->lock); | |
333 | user->qnkeys--; | |
334 | user->qnbytes -= quotalen; | |
335 | spin_unlock(&user->lock); | |
336 | } | |
337 | key_user_put(user); | |
338 | no_memory_1: | |
339 | key = ERR_PTR(-ENOMEM); | |
340 | goto error; | |
341 | ||
342 | no_quota: | |
343 | spin_unlock(&user->lock); | |
344 | key_user_put(user); | |
345 | key = ERR_PTR(-EDQUOT); | |
346 | goto error; | |
347 | ||
348 | } /* end key_alloc() */ | |
349 | ||
350 | EXPORT_SYMBOL(key_alloc); | |
351 | ||
352 | /*****************************************************************************/ | |
353 | /* | |
354 | * reserve an amount of quota for the key's payload | |
355 | */ | |
356 | int key_payload_reserve(struct key *key, size_t datalen) | |
357 | { | |
358 | int delta = (int)datalen - key->datalen; | |
359 | int ret = 0; | |
360 | ||
361 | key_check(key); | |
362 | ||
363 | /* contemplate the quota adjustment */ | |
364 | if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) { | |
365 | unsigned maxbytes = (key->user->uid == 0) ? | |
366 | key_quota_root_maxbytes : key_quota_maxbytes; | |
367 | ||
368 | spin_lock(&key->user->lock); | |
369 | ||
370 | if (delta > 0 && | |
371 | (key->user->qnbytes + delta >= maxbytes || | |
372 | key->user->qnbytes + delta < key->user->qnbytes)) { | |
373 | ret = -EDQUOT; | |
374 | } | |
375 | else { | |
376 | key->user->qnbytes += delta; | |
377 | key->quotalen += delta; | |
378 | } | |
379 | spin_unlock(&key->user->lock); | |
380 | } | |
381 | ||
382 | /* change the recorded data length if that didn't generate an error */ | |
383 | if (ret == 0) | |
384 | key->datalen = datalen; | |
385 | ||
386 | return ret; | |
387 | ||
388 | } /* end key_payload_reserve() */ | |
389 | ||
390 | EXPORT_SYMBOL(key_payload_reserve); | |
391 | ||
392 | /*****************************************************************************/ | |
393 | /* | |
394 | * instantiate a key and link it into the target keyring atomically | |
395 | * - called with the target keyring's semaphore writelocked | |
396 | */ | |
397 | static int __key_instantiate_and_link(struct key *key, | |
398 | const void *data, | |
399 | size_t datalen, | |
400 | struct key *keyring, | |
401 | struct key *authkey, | |
402 | struct keyring_list **_prealloc) | |
403 | { | |
404 | int ret, awaken; | |
405 | ||
406 | key_check(key); | |
407 | key_check(keyring); | |
408 | ||
409 | awaken = 0; | |
410 | ret = -EBUSY; | |
411 | ||
412 | mutex_lock(&key_construction_mutex); | |
413 | ||
414 | /* can't instantiate twice */ | |
415 | if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { | |
416 | /* instantiate the key */ | |
417 | ret = key->type->instantiate(key, data, datalen); | |
418 | ||
419 | if (ret == 0) { | |
420 | /* mark the key as being instantiated */ | |
421 | atomic_inc(&key->user->nikeys); | |
422 | set_bit(KEY_FLAG_INSTANTIATED, &key->flags); | |
423 | ||
424 | if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) | |
425 | awaken = 1; | |
426 | ||
427 | /* and link it into the destination keyring */ | |
428 | if (keyring) | |
429 | __key_link(keyring, key, _prealloc); | |
430 | ||
431 | /* disable the authorisation key */ | |
432 | if (authkey) | |
433 | key_revoke(authkey); | |
434 | } | |
435 | } | |
436 | ||
437 | mutex_unlock(&key_construction_mutex); | |
438 | ||
439 | /* wake up anyone waiting for a key to be constructed */ | |
440 | if (awaken) | |
441 | wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); | |
442 | ||
443 | return ret; | |
444 | ||
445 | } /* end __key_instantiate_and_link() */ | |
446 | ||
447 | /*****************************************************************************/ | |
448 | /* | |
449 | * instantiate a key and link it into the target keyring atomically | |
450 | */ | |
451 | int key_instantiate_and_link(struct key *key, | |
452 | const void *data, | |
453 | size_t datalen, | |
454 | struct key *keyring, | |
455 | struct key *authkey) | |
456 | { | |
457 | struct keyring_list *prealloc; | |
458 | int ret; | |
459 | ||
460 | if (keyring) { | |
461 | ret = __key_link_begin(keyring, key->type, key->description, | |
462 | &prealloc); | |
463 | if (ret < 0) | |
464 | return ret; | |
465 | } | |
466 | ||
467 | ret = __key_instantiate_and_link(key, data, datalen, keyring, authkey, | |
468 | &prealloc); | |
469 | ||
470 | if (keyring) | |
471 | __key_link_end(keyring, key->type, prealloc); | |
472 | ||
473 | return ret; | |
474 | ||
475 | } /* end key_instantiate_and_link() */ | |
476 | ||
477 | EXPORT_SYMBOL(key_instantiate_and_link); | |
478 | ||
479 | /*****************************************************************************/ | |
480 | /* | |
481 | * negatively instantiate a key and link it into the target keyring atomically | |
482 | */ | |
483 | int key_negate_and_link(struct key *key, | |
484 | unsigned timeout, | |
485 | struct key *keyring, | |
486 | struct key *authkey) | |
487 | { | |
488 | struct keyring_list *prealloc; | |
489 | struct timespec now; | |
490 | int ret, awaken, link_ret = 0; | |
491 | ||
492 | key_check(key); | |
493 | key_check(keyring); | |
494 | ||
495 | awaken = 0; | |
496 | ret = -EBUSY; | |
497 | ||
498 | if (keyring) | |
499 | link_ret = __key_link_begin(keyring, key->type, | |
500 | key->description, &prealloc); | |
501 | ||
502 | mutex_lock(&key_construction_mutex); | |
503 | ||
504 | /* can't instantiate twice */ | |
505 | if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { | |
506 | /* mark the key as being negatively instantiated */ | |
507 | atomic_inc(&key->user->nikeys); | |
508 | set_bit(KEY_FLAG_NEGATIVE, &key->flags); | |
509 | set_bit(KEY_FLAG_INSTANTIATED, &key->flags); | |
510 | now = current_kernel_time(); | |
511 | key->expiry = now.tv_sec + timeout; | |
512 | key_schedule_gc(key->expiry + key_gc_delay); | |
513 | ||
514 | if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) | |
515 | awaken = 1; | |
516 | ||
517 | ret = 0; | |
518 | ||
519 | /* and link it into the destination keyring */ | |
520 | if (keyring && link_ret == 0) | |
521 | __key_link(keyring, key, &prealloc); | |
522 | ||
523 | /* disable the authorisation key */ | |
524 | if (authkey) | |
525 | key_revoke(authkey); | |
526 | } | |
527 | ||
528 | mutex_unlock(&key_construction_mutex); | |
529 | ||
530 | if (keyring) | |
531 | __key_link_end(keyring, key->type, prealloc); | |
532 | ||
533 | /* wake up anyone waiting for a key to be constructed */ | |
534 | if (awaken) | |
535 | wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); | |
536 | ||
537 | return ret == 0 ? link_ret : ret; | |
538 | ||
539 | } /* end key_negate_and_link() */ | |
540 | ||
541 | EXPORT_SYMBOL(key_negate_and_link); | |
542 | ||
543 | /*****************************************************************************/ | |
544 | /* | |
545 | * do cleaning up in process context so that we don't have to disable | |
546 | * interrupts all over the place | |
547 | */ | |
548 | static void key_cleanup(struct work_struct *work) | |
549 | { | |
550 | struct rb_node *_n; | |
551 | struct key *key; | |
552 | ||
553 | go_again: | |
554 | /* look for a dead key in the tree */ | |
555 | spin_lock(&key_serial_lock); | |
556 | ||
557 | for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) { | |
558 | key = rb_entry(_n, struct key, serial_node); | |
559 | ||
560 | if (atomic_read(&key->usage) == 0) | |
561 | goto found_dead_key; | |
562 | } | |
563 | ||
564 | spin_unlock(&key_serial_lock); | |
565 | return; | |
566 | ||
567 | found_dead_key: | |
568 | /* we found a dead key - once we've removed it from the tree, we can | |
569 | * drop the lock */ | |
570 | rb_erase(&key->serial_node, &key_serial_tree); | |
571 | spin_unlock(&key_serial_lock); | |
572 | ||
573 | key_check(key); | |
574 | ||
575 | security_key_free(key); | |
576 | ||
577 | /* deal with the user's key tracking and quota */ | |
578 | if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) { | |
579 | spin_lock(&key->user->lock); | |
580 | key->user->qnkeys--; | |
581 | key->user->qnbytes -= key->quotalen; | |
582 | spin_unlock(&key->user->lock); | |
583 | } | |
584 | ||
585 | atomic_dec(&key->user->nkeys); | |
586 | if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) | |
587 | atomic_dec(&key->user->nikeys); | |
588 | ||
589 | key_user_put(key->user); | |
590 | ||
591 | /* now throw away the key memory */ | |
592 | if (key->type->destroy) | |
593 | key->type->destroy(key); | |
594 | ||
595 | kfree(key->description); | |
596 | ||
597 | #ifdef KEY_DEBUGGING | |
598 | key->magic = KEY_DEBUG_MAGIC_X; | |
599 | #endif | |
600 | kmem_cache_free(key_jar, key); | |
601 | ||
602 | /* there may, of course, be more than one key to destroy */ | |
603 | goto go_again; | |
604 | ||
605 | } /* end key_cleanup() */ | |
606 | ||
607 | /*****************************************************************************/ | |
608 | /* | |
609 | * dispose of a reference to a key | |
610 | * - when all the references are gone, we schedule the cleanup task to come and | |
611 | * pull it out of the tree in definite process context | |
612 | */ | |
613 | void key_put(struct key *key) | |
614 | { | |
615 | if (key) { | |
616 | key_check(key); | |
617 | ||
618 | if (atomic_dec_and_test(&key->usage)) | |
619 | schedule_work(&key_cleanup_task); | |
620 | } | |
621 | ||
622 | } /* end key_put() */ | |
623 | ||
624 | EXPORT_SYMBOL(key_put); | |
625 | ||
626 | /*****************************************************************************/ | |
627 | /* | |
628 | * find a key by its serial number | |
629 | */ | |
630 | struct key *key_lookup(key_serial_t id) | |
631 | { | |
632 | struct rb_node *n; | |
633 | struct key *key; | |
634 | ||
635 | spin_lock(&key_serial_lock); | |
636 | ||
637 | /* search the tree for the specified key */ | |
638 | n = key_serial_tree.rb_node; | |
639 | while (n) { | |
640 | key = rb_entry(n, struct key, serial_node); | |
641 | ||
642 | if (id < key->serial) | |
643 | n = n->rb_left; | |
644 | else if (id > key->serial) | |
645 | n = n->rb_right; | |
646 | else | |
647 | goto found; | |
648 | } | |
649 | ||
650 | not_found: | |
651 | key = ERR_PTR(-ENOKEY); | |
652 | goto error; | |
653 | ||
654 | found: | |
655 | /* pretend it doesn't exist if it is awaiting deletion */ | |
656 | if (atomic_read(&key->usage) == 0) | |
657 | goto not_found; | |
658 | ||
659 | /* this races with key_put(), but that doesn't matter since key_put() | |
660 | * doesn't actually change the key | |
661 | */ | |
662 | atomic_inc(&key->usage); | |
663 | ||
664 | error: | |
665 | spin_unlock(&key_serial_lock); | |
666 | return key; | |
667 | ||
668 | } /* end key_lookup() */ | |
669 | ||
670 | /*****************************************************************************/ | |
671 | /* | |
672 | * find and lock the specified key type against removal | |
673 | * - we return with the sem readlocked | |
674 | */ | |
675 | struct key_type *key_type_lookup(const char *type) | |
676 | { | |
677 | struct key_type *ktype; | |
678 | ||
679 | down_read(&key_types_sem); | |
680 | ||
681 | /* look up the key type to see if it's one of the registered kernel | |
682 | * types */ | |
683 | list_for_each_entry(ktype, &key_types_list, link) { | |
684 | if (strcmp(ktype->name, type) == 0) | |
685 | goto found_kernel_type; | |
686 | } | |
687 | ||
688 | up_read(&key_types_sem); | |
689 | ktype = ERR_PTR(-ENOKEY); | |
690 | ||
691 | found_kernel_type: | |
692 | return ktype; | |
693 | ||
694 | } /* end key_type_lookup() */ | |
695 | ||
696 | /*****************************************************************************/ | |
697 | /* | |
698 | * unlock a key type | |
699 | */ | |
700 | void key_type_put(struct key_type *ktype) | |
701 | { | |
702 | up_read(&key_types_sem); | |
703 | ||
704 | } /* end key_type_put() */ | |
705 | ||
706 | /*****************************************************************************/ | |
707 | /* | |
708 | * attempt to update an existing key | |
709 | * - the key has an incremented refcount | |
710 | * - we need to put the key if we get an error | |
711 | */ | |
712 | static inline key_ref_t __key_update(key_ref_t key_ref, | |
713 | const void *payload, size_t plen) | |
714 | { | |
715 | struct key *key = key_ref_to_ptr(key_ref); | |
716 | int ret; | |
717 | ||
718 | /* need write permission on the key to update it */ | |
719 | ret = key_permission(key_ref, KEY_WRITE); | |
720 | if (ret < 0) | |
721 | goto error; | |
722 | ||
723 | ret = -EEXIST; | |
724 | if (!key->type->update) | |
725 | goto error; | |
726 | ||
727 | down_write(&key->sem); | |
728 | ||
729 | ret = key->type->update(key, payload, plen); | |
730 | if (ret == 0) | |
731 | /* updating a negative key instantiates it */ | |
732 | clear_bit(KEY_FLAG_NEGATIVE, &key->flags); | |
733 | ||
734 | up_write(&key->sem); | |
735 | ||
736 | if (ret < 0) | |
737 | goto error; | |
738 | out: | |
739 | return key_ref; | |
740 | ||
741 | error: | |
742 | key_put(key); | |
743 | key_ref = ERR_PTR(ret); | |
744 | goto out; | |
745 | ||
746 | } /* end __key_update() */ | |
747 | ||
748 | /*****************************************************************************/ | |
749 | /* | |
750 | * search the specified keyring for a key of the same description; if one is | |
751 | * found, update it, otherwise add a new one | |
752 | */ | |
753 | key_ref_t key_create_or_update(key_ref_t keyring_ref, | |
754 | const char *type, | |
755 | const char *description, | |
756 | const void *payload, | |
757 | size_t plen, | |
758 | key_perm_t perm, | |
759 | unsigned long flags) | |
760 | { | |
761 | struct keyring_list *prealloc; | |
762 | const struct cred *cred = current_cred(); | |
763 | struct key_type *ktype; | |
764 | struct key *keyring, *key = NULL; | |
765 | key_ref_t key_ref; | |
766 | int ret; | |
767 | ||
768 | /* look up the key type to see if it's one of the registered kernel | |
769 | * types */ | |
770 | ktype = key_type_lookup(type); | |
771 | if (IS_ERR(ktype)) { | |
772 | key_ref = ERR_PTR(-ENODEV); | |
773 | goto error; | |
774 | } | |
775 | ||
776 | key_ref = ERR_PTR(-EINVAL); | |
777 | if (!ktype->match || !ktype->instantiate) | |
778 | goto error_2; | |
779 | ||
780 | keyring = key_ref_to_ptr(keyring_ref); | |
781 | ||
782 | key_check(keyring); | |
783 | ||
784 | key_ref = ERR_PTR(-ENOTDIR); | |
785 | if (keyring->type != &key_type_keyring) | |
786 | goto error_2; | |
787 | ||
788 | ret = __key_link_begin(keyring, ktype, description, &prealloc); | |
789 | if (ret < 0) | |
790 | goto error_2; | |
791 | ||
792 | /* if we're going to allocate a new key, we're going to have | |
793 | * to modify the keyring */ | |
794 | ret = key_permission(keyring_ref, KEY_WRITE); | |
795 | if (ret < 0) { | |
796 | key_ref = ERR_PTR(ret); | |
797 | goto error_3; | |
798 | } | |
799 | ||
800 | /* if it's possible to update this type of key, search for an existing | |
801 | * key of the same type and description in the destination keyring and | |
802 | * update that instead if possible | |
803 | */ | |
804 | if (ktype->update) { | |
805 | key_ref = __keyring_search_one(keyring_ref, ktype, description, | |
806 | 0); | |
807 | if (!IS_ERR(key_ref)) | |
808 | goto found_matching_key; | |
809 | } | |
810 | ||
811 | /* if the client doesn't provide, decide on the permissions we want */ | |
812 | if (perm == KEY_PERM_UNDEF) { | |
813 | perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR; | |
814 | perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR; | |
815 | ||
816 | if (ktype->read) | |
817 | perm |= KEY_POS_READ | KEY_USR_READ; | |
818 | ||
819 | if (ktype == &key_type_keyring || ktype->update) | |
820 | perm |= KEY_USR_WRITE; | |
821 | } | |
822 | ||
823 | /* allocate a new key */ | |
824 | key = key_alloc(ktype, description, cred->fsuid, cred->fsgid, cred, | |
825 | perm, flags); | |
826 | if (IS_ERR(key)) { | |
827 | key_ref = ERR_CAST(key); | |
828 | goto error_3; | |
829 | } | |
830 | ||
831 | /* instantiate it and link it into the target keyring */ | |
832 | ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL, | |
833 | &prealloc); | |
834 | if (ret < 0) { | |
835 | key_put(key); | |
836 | key_ref = ERR_PTR(ret); | |
837 | goto error_3; | |
838 | } | |
839 | ||
840 | key_ref = make_key_ref(key, is_key_possessed(keyring_ref)); | |
841 | ||
842 | error_3: | |
843 | __key_link_end(keyring, ktype, prealloc); | |
844 | error_2: | |
845 | key_type_put(ktype); | |
846 | error: | |
847 | return key_ref; | |
848 | ||
849 | found_matching_key: | |
850 | /* we found a matching key, so we're going to try to update it | |
851 | * - we can drop the locks first as we have the key pinned | |
852 | */ | |
853 | __key_link_end(keyring, ktype, prealloc); | |
854 | key_type_put(ktype); | |
855 | ||
856 | key_ref = __key_update(key_ref, payload, plen); | |
857 | goto error; | |
858 | ||
859 | } /* end key_create_or_update() */ | |
860 | ||
861 | EXPORT_SYMBOL(key_create_or_update); | |
862 | ||
863 | /*****************************************************************************/ | |
864 | /* | |
865 | * update a key | |
866 | */ | |
867 | int key_update(key_ref_t key_ref, const void *payload, size_t plen) | |
868 | { | |
869 | struct key *key = key_ref_to_ptr(key_ref); | |
870 | int ret; | |
871 | ||
872 | key_check(key); | |
873 | ||
874 | /* the key must be writable */ | |
875 | ret = key_permission(key_ref, KEY_WRITE); | |
876 | if (ret < 0) | |
877 | goto error; | |
878 | ||
879 | /* attempt to update it if supported */ | |
880 | ret = -EOPNOTSUPP; | |
881 | if (key->type->update) { | |
882 | down_write(&key->sem); | |
883 | ||
884 | ret = key->type->update(key, payload, plen); | |
885 | if (ret == 0) | |
886 | /* updating a negative key instantiates it */ | |
887 | clear_bit(KEY_FLAG_NEGATIVE, &key->flags); | |
888 | ||
889 | up_write(&key->sem); | |
890 | } | |
891 | ||
892 | error: | |
893 | return ret; | |
894 | ||
895 | } /* end key_update() */ | |
896 | ||
897 | EXPORT_SYMBOL(key_update); | |
898 | ||
899 | /*****************************************************************************/ | |
900 | /* | |
901 | * revoke a key | |
902 | */ | |
903 | void key_revoke(struct key *key) | |
904 | { | |
905 | struct timespec now; | |
906 | time_t time; | |
907 | ||
908 | key_check(key); | |
909 | ||
910 | /* make sure no one's trying to change or use the key when we mark it | |
911 | * - we tell lockdep that we might nest because we might be revoking an | |
912 | * authorisation key whilst holding the sem on a key we've just | |
913 | * instantiated | |
914 | */ | |
915 | down_write_nested(&key->sem, 1); | |
916 | if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) && | |
917 | key->type->revoke) | |
918 | key->type->revoke(key); | |
919 | ||
920 | /* set the death time to no more than the expiry time */ | |
921 | now = current_kernel_time(); | |
922 | time = now.tv_sec; | |
923 | if (key->revoked_at == 0 || key->revoked_at > time) { | |
924 | key->revoked_at = time; | |
925 | key_schedule_gc(key->revoked_at + key_gc_delay); | |
926 | } | |
927 | ||
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 | /* mark all the keys of this type dead */ | |
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 | key->type = &key_type_dead; | |
986 | set_bit(KEY_FLAG_DEAD, &key->flags); | |
987 | } | |
988 | } | |
989 | ||
990 | spin_unlock(&key_serial_lock); | |
991 | ||
992 | /* make sure everyone revalidates their keys */ | |
993 | synchronize_rcu(); | |
994 | ||
995 | /* we should now be able to destroy the payloads of all the keys of | |
996 | * this type with impunity */ | |
997 | spin_lock(&key_serial_lock); | |
998 | ||
999 | for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) { | |
1000 | key = rb_entry(_n, struct key, serial_node); | |
1001 | ||
1002 | if (key->type == ktype) { | |
1003 | if (ktype->destroy) | |
1004 | ktype->destroy(key); | |
1005 | memset(&key->payload, KEY_DESTROY, sizeof(key->payload)); | |
1006 | } | |
1007 | } | |
1008 | ||
1009 | spin_unlock(&key_serial_lock); | |
1010 | up_write(&key_types_sem); | |
1011 | ||
1012 | key_schedule_gc(0); | |
1013 | ||
1014 | } /* end unregister_key_type() */ | |
1015 | ||
1016 | EXPORT_SYMBOL(unregister_key_type); | |
1017 | ||
1018 | /*****************************************************************************/ | |
1019 | /* | |
1020 | * initialise the key management stuff | |
1021 | */ | |
1022 | void __init key_init(void) | |
1023 | { | |
1024 | /* allocate a slab in which we can store keys */ | |
1025 | key_jar = kmem_cache_create("key_jar", sizeof(struct key), | |
1026 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
1027 | ||
1028 | /* add the special key types */ | |
1029 | list_add_tail(&key_type_keyring.link, &key_types_list); | |
1030 | list_add_tail(&key_type_dead.link, &key_types_list); | |
1031 | list_add_tail(&key_type_user.link, &key_types_list); | |
1032 | ||
1033 | /* record the root user tracking */ | |
1034 | rb_link_node(&root_key_user.node, | |
1035 | NULL, | |
1036 | &key_user_tree.rb_node); | |
1037 | ||
1038 | rb_insert_color(&root_key_user.node, | |
1039 | &key_user_tree); | |
1040 | ||
1041 | } /* end key_init() */ |