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1da177e4 LT |
1 | /* key.c: basic authentication token and access key management |
2 | * | |
3dccff8d | 3 | * Copyright (C) 2004-6 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> | |
a7807a32 | 14 | #include <linux/poison.h> |
1da177e4 LT |
15 | #include <linux/sched.h> |
16 | #include <linux/slab.h> | |
29db9190 | 17 | #include <linux/security.h> |
1da177e4 | 18 | #include <linux/workqueue.h> |
e51f6d34 | 19 | #include <linux/random.h> |
1da177e4 LT |
20 | #include <linux/err.h> |
21 | #include "internal.h" | |
22 | ||
e18b890b | 23 | static struct kmem_cache *key_jar; |
1da177e4 LT |
24 | struct rb_root key_serial_tree; /* tree of keys indexed by serial */ |
25 | DEFINE_SPINLOCK(key_serial_lock); | |
26 | ||
27 | struct rb_root key_user_tree; /* tree of quota records indexed by UID */ | |
28 | DEFINE_SPINLOCK(key_user_lock); | |
29 | ||
30 | static LIST_HEAD(key_types_list); | |
31 | static DECLARE_RWSEM(key_types_sem); | |
32 | ||
65f27f38 DH |
33 | static void key_cleanup(struct work_struct *work); |
34 | static DECLARE_WORK(key_cleanup_task, key_cleanup); | |
1da177e4 LT |
35 | |
36 | /* we serialise key instantiation and link */ | |
37 | DECLARE_RWSEM(key_construction_sem); | |
38 | ||
39 | /* any key who's type gets unegistered will be re-typed to this */ | |
1ae8f407 | 40 | static struct key_type key_type_dead = { |
1da177e4 LT |
41 | .name = "dead", |
42 | }; | |
43 | ||
44 | #ifdef KEY_DEBUGGING | |
45 | void __key_check(const struct key *key) | |
46 | { | |
47 | printk("__key_check: key %p {%08x} should be {%08x}\n", | |
48 | key, key->magic, KEY_DEBUG_MAGIC); | |
49 | BUG(); | |
50 | } | |
51 | #endif | |
52 | ||
53 | /*****************************************************************************/ | |
54 | /* | |
55 | * get the key quota record for a user, allocating a new record if one doesn't | |
56 | * already exist | |
57 | */ | |
58 | struct key_user *key_user_lookup(uid_t uid) | |
59 | { | |
60 | struct key_user *candidate = NULL, *user; | |
61 | struct rb_node *parent = NULL; | |
62 | struct rb_node **p; | |
63 | ||
64 | try_again: | |
65 | p = &key_user_tree.rb_node; | |
66 | spin_lock(&key_user_lock); | |
67 | ||
68 | /* search the tree for a user record with a matching UID */ | |
69 | while (*p) { | |
70 | parent = *p; | |
71 | user = rb_entry(parent, struct key_user, node); | |
72 | ||
73 | if (uid < user->uid) | |
74 | p = &(*p)->rb_left; | |
75 | else if (uid > user->uid) | |
76 | p = &(*p)->rb_right; | |
77 | else | |
78 | goto found; | |
79 | } | |
80 | ||
81 | /* if we get here, we failed to find a match in the tree */ | |
82 | if (!candidate) { | |
83 | /* allocate a candidate user record if we don't already have | |
84 | * one */ | |
85 | spin_unlock(&key_user_lock); | |
86 | ||
87 | user = NULL; | |
88 | candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL); | |
89 | if (unlikely(!candidate)) | |
90 | goto out; | |
91 | ||
92 | /* the allocation may have scheduled, so we need to repeat the | |
93 | * search lest someone else added the record whilst we were | |
94 | * asleep */ | |
95 | goto try_again; | |
96 | } | |
97 | ||
98 | /* if we get here, then the user record still hadn't appeared on the | |
99 | * second pass - so we use the candidate record */ | |
100 | atomic_set(&candidate->usage, 1); | |
101 | atomic_set(&candidate->nkeys, 0); | |
102 | atomic_set(&candidate->nikeys, 0); | |
103 | candidate->uid = uid; | |
104 | candidate->qnkeys = 0; | |
105 | candidate->qnbytes = 0; | |
106 | spin_lock_init(&candidate->lock); | |
107 | INIT_LIST_HEAD(&candidate->consq); | |
108 | ||
109 | rb_link_node(&candidate->node, parent, p); | |
110 | rb_insert_color(&candidate->node, &key_user_tree); | |
111 | spin_unlock(&key_user_lock); | |
112 | user = candidate; | |
113 | goto out; | |
114 | ||
115 | /* okay - we found a user record for this UID */ | |
116 | found: | |
117 | atomic_inc(&user->usage); | |
118 | spin_unlock(&key_user_lock); | |
a7f988ba | 119 | kfree(candidate); |
1da177e4 LT |
120 | out: |
121 | return user; | |
122 | ||
123 | } /* end key_user_lookup() */ | |
124 | ||
125 | /*****************************************************************************/ | |
126 | /* | |
127 | * dispose of a user structure | |
128 | */ | |
129 | void key_user_put(struct key_user *user) | |
130 | { | |
131 | if (atomic_dec_and_lock(&user->usage, &key_user_lock)) { | |
132 | rb_erase(&user->node, &key_user_tree); | |
133 | spin_unlock(&key_user_lock); | |
134 | ||
135 | kfree(user); | |
136 | } | |
137 | ||
138 | } /* end key_user_put() */ | |
139 | ||
140 | /*****************************************************************************/ | |
141 | /* | |
142 | * insert a key with a fixed serial number | |
143 | */ | |
144 | static void __init __key_insert_serial(struct key *key) | |
145 | { | |
146 | struct rb_node *parent, **p; | |
147 | struct key *xkey; | |
148 | ||
149 | parent = NULL; | |
150 | p = &key_serial_tree.rb_node; | |
151 | ||
152 | while (*p) { | |
153 | parent = *p; | |
154 | xkey = rb_entry(parent, struct key, serial_node); | |
155 | ||
156 | if (key->serial < xkey->serial) | |
157 | p = &(*p)->rb_left; | |
158 | else if (key->serial > xkey->serial) | |
159 | p = &(*p)->rb_right; | |
160 | else | |
161 | BUG(); | |
162 | } | |
163 | ||
164 | /* we've found a suitable hole - arrange for this key to occupy it */ | |
165 | rb_link_node(&key->serial_node, parent, p); | |
166 | rb_insert_color(&key->serial_node, &key_serial_tree); | |
167 | ||
168 | } /* end __key_insert_serial() */ | |
169 | ||
170 | /*****************************************************************************/ | |
171 | /* | |
172 | * assign a key the next unique serial number | |
e51f6d34 ML |
173 | * - these are assigned randomly to avoid security issues through covert |
174 | * channel problems | |
1da177e4 LT |
175 | */ |
176 | static inline void key_alloc_serial(struct key *key) | |
177 | { | |
178 | struct rb_node *parent, **p; | |
179 | struct key *xkey; | |
180 | ||
e51f6d34 | 181 | /* propose a random serial number and look for a hole for it in the |
1da177e4 | 182 | * serial number tree */ |
e51f6d34 ML |
183 | do { |
184 | get_random_bytes(&key->serial, sizeof(key->serial)); | |
185 | ||
186 | key->serial >>= 1; /* negative numbers are not permitted */ | |
187 | } while (key->serial < 3); | |
188 | ||
189 | spin_lock(&key_serial_lock); | |
1da177e4 | 190 | |
9ad0830f | 191 | attempt_insertion: |
1da177e4 LT |
192 | parent = NULL; |
193 | p = &key_serial_tree.rb_node; | |
194 | ||
195 | while (*p) { | |
196 | parent = *p; | |
197 | xkey = rb_entry(parent, struct key, serial_node); | |
198 | ||
199 | if (key->serial < xkey->serial) | |
200 | p = &(*p)->rb_left; | |
201 | else if (key->serial > xkey->serial) | |
202 | p = &(*p)->rb_right; | |
203 | else | |
204 | goto serial_exists; | |
205 | } | |
9ad0830f DH |
206 | |
207 | /* we've found a suitable hole - arrange for this key to occupy it */ | |
208 | rb_link_node(&key->serial_node, parent, p); | |
209 | rb_insert_color(&key->serial_node, &key_serial_tree); | |
210 | ||
211 | spin_unlock(&key_serial_lock); | |
212 | return; | |
1da177e4 LT |
213 | |
214 | /* we found a key with the proposed serial number - walk the tree from | |
215 | * that point looking for the next unused serial number */ | |
e51f6d34 | 216 | serial_exists: |
1da177e4 | 217 | for (;;) { |
e51f6d34 | 218 | key->serial++; |
9ad0830f DH |
219 | if (key->serial < 3) { |
220 | key->serial = 3; | |
221 | goto attempt_insertion; | |
222 | } | |
1da177e4 LT |
223 | |
224 | parent = rb_next(parent); | |
225 | if (!parent) | |
9ad0830f | 226 | goto attempt_insertion; |
1da177e4 LT |
227 | |
228 | xkey = rb_entry(parent, struct key, serial_node); | |
229 | if (key->serial < xkey->serial) | |
9ad0830f | 230 | goto attempt_insertion; |
1da177e4 LT |
231 | } |
232 | ||
1da177e4 LT |
233 | } /* end key_alloc_serial() */ |
234 | ||
235 | /*****************************************************************************/ | |
236 | /* | |
237 | * allocate a key of the specified type | |
238 | * - update the user's quota to reflect the existence of the key | |
8d9067bd DH |
239 | * - called from a key-type operation with key_types_sem read-locked by |
240 | * key_create_or_update() | |
241 | * - this prevents unregistration of the key type | |
1da177e4 LT |
242 | * - upon return the key is as yet uninstantiated; the caller needs to either |
243 | * instantiate the key or discard it before returning | |
244 | */ | |
245 | struct key *key_alloc(struct key_type *type, const char *desc, | |
d720024e | 246 | uid_t uid, gid_t gid, struct task_struct *ctx, |
7e047ef5 | 247 | key_perm_t perm, unsigned long flags) |
1da177e4 LT |
248 | { |
249 | struct key_user *user = NULL; | |
250 | struct key *key; | |
251 | size_t desclen, quotalen; | |
29db9190 | 252 | int ret; |
1da177e4 LT |
253 | |
254 | key = ERR_PTR(-EINVAL); | |
255 | if (!desc || !*desc) | |
256 | goto error; | |
257 | ||
258 | desclen = strlen(desc) + 1; | |
259 | quotalen = desclen + type->def_datalen; | |
260 | ||
261 | /* get hold of the key tracking for this user */ | |
262 | user = key_user_lookup(uid); | |
263 | if (!user) | |
264 | goto no_memory_1; | |
265 | ||
266 | /* check that the user's quota permits allocation of another key and | |
267 | * its description */ | |
7e047ef5 | 268 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { |
1da177e4 | 269 | spin_lock(&user->lock); |
7e047ef5 DH |
270 | if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) { |
271 | if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS || | |
272 | user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES | |
273 | ) | |
274 | goto no_quota; | |
275 | } | |
1da177e4 LT |
276 | |
277 | user->qnkeys++; | |
278 | user->qnbytes += quotalen; | |
279 | spin_unlock(&user->lock); | |
280 | } | |
281 | ||
282 | /* allocate and initialise the key and its description */ | |
e94b1766 | 283 | key = kmem_cache_alloc(key_jar, GFP_KERNEL); |
1da177e4 LT |
284 | if (!key) |
285 | goto no_memory_2; | |
286 | ||
287 | if (desc) { | |
48ad504e | 288 | key->description = kmemdup(desc, desclen, GFP_KERNEL); |
1da177e4 LT |
289 | if (!key->description) |
290 | goto no_memory_3; | |
1da177e4 LT |
291 | } |
292 | ||
293 | atomic_set(&key->usage, 1); | |
1da177e4 LT |
294 | init_rwsem(&key->sem); |
295 | key->type = type; | |
296 | key->user = user; | |
297 | key->quotalen = quotalen; | |
298 | key->datalen = type->def_datalen; | |
299 | key->uid = uid; | |
300 | key->gid = gid; | |
301 | key->perm = perm; | |
302 | key->flags = 0; | |
303 | key->expiry = 0; | |
304 | key->payload.data = NULL; | |
29db9190 | 305 | key->security = NULL; |
1da177e4 | 306 | |
7e047ef5 | 307 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) |
76d8aeab | 308 | key->flags |= 1 << KEY_FLAG_IN_QUOTA; |
1da177e4 LT |
309 | |
310 | memset(&key->type_data, 0, sizeof(key->type_data)); | |
311 | ||
312 | #ifdef KEY_DEBUGGING | |
313 | key->magic = KEY_DEBUG_MAGIC; | |
314 | #endif | |
315 | ||
29db9190 | 316 | /* let the security module know about the key */ |
7e047ef5 | 317 | ret = security_key_alloc(key, ctx, flags); |
29db9190 DH |
318 | if (ret < 0) |
319 | goto security_error; | |
320 | ||
1da177e4 LT |
321 | /* publish the key by giving it a serial number */ |
322 | atomic_inc(&user->nkeys); | |
323 | key_alloc_serial(key); | |
324 | ||
29db9190 | 325 | error: |
1da177e4 LT |
326 | return key; |
327 | ||
29db9190 DH |
328 | security_error: |
329 | kfree(key->description); | |
1da177e4 | 330 | kmem_cache_free(key_jar, key); |
7e047ef5 | 331 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { |
1da177e4 LT |
332 | spin_lock(&user->lock); |
333 | user->qnkeys--; | |
334 | user->qnbytes -= quotalen; | |
335 | spin_unlock(&user->lock); | |
336 | } | |
337 | key_user_put(user); | |
29db9190 DH |
338 | key = ERR_PTR(ret); |
339 | goto error; | |
340 | ||
341 | no_memory_3: | |
342 | kmem_cache_free(key_jar, key); | |
343 | no_memory_2: | |
7e047ef5 | 344 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { |
29db9190 DH |
345 | spin_lock(&user->lock); |
346 | user->qnkeys--; | |
347 | user->qnbytes -= quotalen; | |
348 | spin_unlock(&user->lock); | |
349 | } | |
350 | key_user_put(user); | |
351 | no_memory_1: | |
1da177e4 LT |
352 | key = ERR_PTR(-ENOMEM); |
353 | goto error; | |
354 | ||
29db9190 | 355 | no_quota: |
1da177e4 LT |
356 | spin_unlock(&user->lock); |
357 | key_user_put(user); | |
358 | key = ERR_PTR(-EDQUOT); | |
359 | goto error; | |
360 | ||
361 | } /* end key_alloc() */ | |
362 | ||
363 | EXPORT_SYMBOL(key_alloc); | |
364 | ||
365 | /*****************************************************************************/ | |
366 | /* | |
367 | * reserve an amount of quota for the key's payload | |
368 | */ | |
369 | int key_payload_reserve(struct key *key, size_t datalen) | |
370 | { | |
371 | int delta = (int) datalen - key->datalen; | |
372 | int ret = 0; | |
373 | ||
374 | key_check(key); | |
375 | ||
376 | /* contemplate the quota adjustment */ | |
76d8aeab | 377 | if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) { |
1da177e4 LT |
378 | spin_lock(&key->user->lock); |
379 | ||
380 | if (delta > 0 && | |
381 | key->user->qnbytes + delta > KEYQUOTA_MAX_BYTES | |
382 | ) { | |
383 | ret = -EDQUOT; | |
384 | } | |
385 | else { | |
386 | key->user->qnbytes += delta; | |
387 | key->quotalen += delta; | |
388 | } | |
389 | spin_unlock(&key->user->lock); | |
390 | } | |
391 | ||
392 | /* change the recorded data length if that didn't generate an error */ | |
393 | if (ret == 0) | |
394 | key->datalen = datalen; | |
395 | ||
396 | return ret; | |
397 | ||
398 | } /* end key_payload_reserve() */ | |
399 | ||
400 | EXPORT_SYMBOL(key_payload_reserve); | |
401 | ||
402 | /*****************************************************************************/ | |
403 | /* | |
404 | * instantiate a key and link it into the target keyring atomically | |
405 | * - called with the target keyring's semaphore writelocked | |
406 | */ | |
407 | static int __key_instantiate_and_link(struct key *key, | |
408 | const void *data, | |
409 | size_t datalen, | |
3e30148c DH |
410 | struct key *keyring, |
411 | struct key *instkey) | |
1da177e4 LT |
412 | { |
413 | int ret, awaken; | |
414 | ||
415 | key_check(key); | |
416 | key_check(keyring); | |
417 | ||
418 | awaken = 0; | |
419 | ret = -EBUSY; | |
420 | ||
421 | down_write(&key_construction_sem); | |
422 | ||
423 | /* can't instantiate twice */ | |
76d8aeab | 424 | if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { |
1da177e4 LT |
425 | /* instantiate the key */ |
426 | ret = key->type->instantiate(key, data, datalen); | |
427 | ||
428 | if (ret == 0) { | |
429 | /* mark the key as being instantiated */ | |
1da177e4 | 430 | atomic_inc(&key->user->nikeys); |
76d8aeab | 431 | set_bit(KEY_FLAG_INSTANTIATED, &key->flags); |
1da177e4 | 432 | |
76d8aeab | 433 | if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) |
1da177e4 | 434 | awaken = 1; |
1da177e4 LT |
435 | |
436 | /* and link it into the destination keyring */ | |
437 | if (keyring) | |
438 | ret = __key_link(keyring, key); | |
3e30148c DH |
439 | |
440 | /* disable the authorisation key */ | |
441 | if (instkey) | |
442 | key_revoke(instkey); | |
1da177e4 LT |
443 | } |
444 | } | |
445 | ||
446 | up_write(&key_construction_sem); | |
447 | ||
448 | /* wake up anyone waiting for a key to be constructed */ | |
449 | if (awaken) | |
450 | wake_up_all(&request_key_conswq); | |
451 | ||
452 | return ret; | |
453 | ||
454 | } /* end __key_instantiate_and_link() */ | |
455 | ||
456 | /*****************************************************************************/ | |
457 | /* | |
458 | * instantiate a key and link it into the target keyring atomically | |
459 | */ | |
460 | int key_instantiate_and_link(struct key *key, | |
461 | const void *data, | |
462 | size_t datalen, | |
3e30148c DH |
463 | struct key *keyring, |
464 | struct key *instkey) | |
1da177e4 LT |
465 | { |
466 | int ret; | |
467 | ||
468 | if (keyring) | |
469 | down_write(&keyring->sem); | |
470 | ||
3e30148c | 471 | ret = __key_instantiate_and_link(key, data, datalen, keyring, instkey); |
1da177e4 LT |
472 | |
473 | if (keyring) | |
474 | up_write(&keyring->sem); | |
475 | ||
476 | return ret; | |
3e30148c | 477 | |
1da177e4 LT |
478 | } /* end key_instantiate_and_link() */ |
479 | ||
480 | EXPORT_SYMBOL(key_instantiate_and_link); | |
481 | ||
482 | /*****************************************************************************/ | |
483 | /* | |
484 | * negatively instantiate a key and link it into the target keyring atomically | |
485 | */ | |
486 | int key_negate_and_link(struct key *key, | |
487 | unsigned timeout, | |
3e30148c DH |
488 | struct key *keyring, |
489 | struct key *instkey) | |
1da177e4 LT |
490 | { |
491 | struct timespec now; | |
492 | int ret, awaken; | |
493 | ||
494 | key_check(key); | |
495 | key_check(keyring); | |
496 | ||
497 | awaken = 0; | |
498 | ret = -EBUSY; | |
499 | ||
500 | if (keyring) | |
501 | down_write(&keyring->sem); | |
502 | ||
503 | down_write(&key_construction_sem); | |
504 | ||
505 | /* can't instantiate twice */ | |
76d8aeab | 506 | if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { |
1da177e4 | 507 | /* mark the key as being negatively instantiated */ |
1da177e4 | 508 | atomic_inc(&key->user->nikeys); |
76d8aeab DH |
509 | set_bit(KEY_FLAG_NEGATIVE, &key->flags); |
510 | set_bit(KEY_FLAG_INSTANTIATED, &key->flags); | |
1da177e4 LT |
511 | now = current_kernel_time(); |
512 | key->expiry = now.tv_sec + timeout; | |
513 | ||
76d8aeab | 514 | if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) |
1da177e4 | 515 | awaken = 1; |
1da177e4 | 516 | |
1da177e4 LT |
517 | ret = 0; |
518 | ||
519 | /* and link it into the destination keyring */ | |
520 | if (keyring) | |
521 | ret = __key_link(keyring, key); | |
3e30148c DH |
522 | |
523 | /* disable the authorisation key */ | |
524 | if (instkey) | |
525 | key_revoke(instkey); | |
1da177e4 LT |
526 | } |
527 | ||
528 | up_write(&key_construction_sem); | |
529 | ||
530 | if (keyring) | |
531 | up_write(&keyring->sem); | |
532 | ||
533 | /* wake up anyone waiting for a key to be constructed */ | |
534 | if (awaken) | |
535 | wake_up_all(&request_key_conswq); | |
536 | ||
537 | return 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 | */ | |
65f27f38 | 548 | static void key_cleanup(struct work_struct *work) |
1da177e4 LT |
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 | ||
76d8aeab DH |
573 | key_check(key); |
574 | ||
29db9190 DH |
575 | security_key_free(key); |
576 | ||
1da177e4 | 577 | /* deal with the user's key tracking and quota */ |
76d8aeab | 578 | if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) { |
1da177e4 LT |
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); | |
76d8aeab | 586 | if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) |
1da177e4 LT |
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: | |
76d8aeab | 655 | /* pretend it doesn't exist if it's dead */ |
1da177e4 | 656 | if (atomic_read(&key->usage) == 0 || |
76d8aeab | 657 | test_bit(KEY_FLAG_DEAD, &key->flags) || |
1da177e4 LT |
658 | key->type == &key_type_dead) |
659 | goto not_found; | |
660 | ||
661 | /* this races with key_put(), but that doesn't matter since key_put() | |
662 | * doesn't actually change the key | |
663 | */ | |
664 | atomic_inc(&key->usage); | |
665 | ||
666 | error: | |
667 | spin_unlock(&key_serial_lock); | |
668 | return key; | |
669 | ||
670 | } /* end key_lookup() */ | |
671 | ||
672 | /*****************************************************************************/ | |
673 | /* | |
674 | * find and lock the specified key type against removal | |
675 | * - we return with the sem readlocked | |
676 | */ | |
677 | struct key_type *key_type_lookup(const char *type) | |
678 | { | |
679 | struct key_type *ktype; | |
680 | ||
681 | down_read(&key_types_sem); | |
682 | ||
683 | /* look up the key type to see if it's one of the registered kernel | |
684 | * types */ | |
685 | list_for_each_entry(ktype, &key_types_list, link) { | |
686 | if (strcmp(ktype->name, type) == 0) | |
687 | goto found_kernel_type; | |
688 | } | |
689 | ||
690 | up_read(&key_types_sem); | |
691 | ktype = ERR_PTR(-ENOKEY); | |
692 | ||
693 | found_kernel_type: | |
694 | return ktype; | |
695 | ||
696 | } /* end key_type_lookup() */ | |
697 | ||
698 | /*****************************************************************************/ | |
699 | /* | |
700 | * unlock a key type | |
701 | */ | |
702 | void key_type_put(struct key_type *ktype) | |
703 | { | |
704 | up_read(&key_types_sem); | |
705 | ||
706 | } /* end key_type_put() */ | |
707 | ||
708 | /*****************************************************************************/ | |
709 | /* | |
710 | * attempt to update an existing key | |
711 | * - the key has an incremented refcount | |
712 | * - we need to put the key if we get an error | |
713 | */ | |
664cceb0 DH |
714 | static inline key_ref_t __key_update(key_ref_t key_ref, |
715 | const void *payload, size_t plen) | |
1da177e4 | 716 | { |
664cceb0 | 717 | struct key *key = key_ref_to_ptr(key_ref); |
1da177e4 LT |
718 | int ret; |
719 | ||
720 | /* need write permission on the key to update it */ | |
29db9190 DH |
721 | ret = key_permission(key_ref, KEY_WRITE); |
722 | if (ret < 0) | |
1da177e4 LT |
723 | goto error; |
724 | ||
725 | ret = -EEXIST; | |
726 | if (!key->type->update) | |
727 | goto error; | |
728 | ||
729 | down_write(&key->sem); | |
730 | ||
731 | ret = key->type->update(key, payload, plen); | |
76d8aeab | 732 | if (ret == 0) |
1da177e4 | 733 | /* updating a negative key instantiates it */ |
76d8aeab | 734 | clear_bit(KEY_FLAG_NEGATIVE, &key->flags); |
1da177e4 LT |
735 | |
736 | up_write(&key->sem); | |
737 | ||
738 | if (ret < 0) | |
739 | goto error; | |
664cceb0 DH |
740 | out: |
741 | return key_ref; | |
1da177e4 | 742 | |
664cceb0 | 743 | error: |
1da177e4 | 744 | key_put(key); |
664cceb0 | 745 | key_ref = ERR_PTR(ret); |
1da177e4 LT |
746 | goto out; |
747 | ||
748 | } /* end __key_update() */ | |
749 | ||
750 | /*****************************************************************************/ | |
751 | /* | |
752 | * search the specified keyring for a key of the same description; if one is | |
753 | * found, update it, otherwise add a new one | |
754 | */ | |
664cceb0 DH |
755 | key_ref_t key_create_or_update(key_ref_t keyring_ref, |
756 | const char *type, | |
757 | const char *description, | |
758 | const void *payload, | |
759 | size_t plen, | |
7e047ef5 | 760 | unsigned long flags) |
1da177e4 LT |
761 | { |
762 | struct key_type *ktype; | |
664cceb0 | 763 | struct key *keyring, *key = NULL; |
1da177e4 | 764 | key_perm_t perm; |
664cceb0 | 765 | key_ref_t key_ref; |
1da177e4 LT |
766 | int ret; |
767 | ||
1da177e4 LT |
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)) { | |
664cceb0 | 772 | key_ref = ERR_PTR(-ENODEV); |
1da177e4 LT |
773 | goto error; |
774 | } | |
775 | ||
664cceb0 | 776 | key_ref = ERR_PTR(-EINVAL); |
1da177e4 LT |
777 | if (!ktype->match || !ktype->instantiate) |
778 | goto error_2; | |
779 | ||
664cceb0 DH |
780 | keyring = key_ref_to_ptr(keyring_ref); |
781 | ||
782 | key_check(keyring); | |
783 | ||
c3a9d654 DH |
784 | key_ref = ERR_PTR(-ENOTDIR); |
785 | if (keyring->type != &key_type_keyring) | |
786 | goto error_2; | |
787 | ||
664cceb0 DH |
788 | down_write(&keyring->sem); |
789 | ||
790 | /* if we're going to allocate a new key, we're going to have | |
791 | * to modify the keyring */ | |
29db9190 DH |
792 | ret = key_permission(keyring_ref, KEY_WRITE); |
793 | if (ret < 0) { | |
794 | key_ref = ERR_PTR(ret); | |
664cceb0 | 795 | goto error_3; |
29db9190 | 796 | } |
664cceb0 | 797 | |
1d9b7d97 DH |
798 | /* if it's possible to update this type of key, search for an existing |
799 | * key of the same type and description in the destination keyring and | |
800 | * update that instead if possible | |
1da177e4 | 801 | */ |
1d9b7d97 DH |
802 | if (ktype->update) { |
803 | key_ref = __keyring_search_one(keyring_ref, ktype, description, | |
804 | 0); | |
805 | if (!IS_ERR(key_ref)) | |
806 | goto found_matching_key; | |
807 | } | |
1da177e4 | 808 | |
1da177e4 | 809 | /* decide on the permissions we want */ |
29db9190 DH |
810 | perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR; |
811 | perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR; | |
1da177e4 LT |
812 | |
813 | if (ktype->read) | |
664cceb0 | 814 | perm |= KEY_POS_READ | KEY_USR_READ; |
1da177e4 LT |
815 | |
816 | if (ktype == &key_type_keyring || ktype->update) | |
817 | perm |= KEY_USR_WRITE; | |
818 | ||
819 | /* allocate a new key */ | |
820 | key = key_alloc(ktype, description, current->fsuid, current->fsgid, | |
7e047ef5 | 821 | current, perm, flags); |
1da177e4 | 822 | if (IS_ERR(key)) { |
664cceb0 | 823 | key_ref = ERR_PTR(PTR_ERR(key)); |
1da177e4 LT |
824 | goto error_3; |
825 | } | |
826 | ||
827 | /* instantiate it and link it into the target keyring */ | |
3e30148c | 828 | ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL); |
1da177e4 LT |
829 | if (ret < 0) { |
830 | key_put(key); | |
664cceb0 DH |
831 | key_ref = ERR_PTR(ret); |
832 | goto error_3; | |
1da177e4 LT |
833 | } |
834 | ||
664cceb0 DH |
835 | key_ref = make_key_ref(key, is_key_possessed(keyring_ref)); |
836 | ||
1da177e4 LT |
837 | error_3: |
838 | up_write(&keyring->sem); | |
839 | error_2: | |
840 | key_type_put(ktype); | |
841 | error: | |
664cceb0 | 842 | return key_ref; |
1da177e4 LT |
843 | |
844 | found_matching_key: | |
845 | /* we found a matching key, so we're going to try to update it | |
846 | * - we can drop the locks first as we have the key pinned | |
847 | */ | |
848 | up_write(&keyring->sem); | |
849 | key_type_put(ktype); | |
850 | ||
664cceb0 | 851 | key_ref = __key_update(key_ref, payload, plen); |
1da177e4 LT |
852 | goto error; |
853 | ||
854 | } /* end key_create_or_update() */ | |
855 | ||
856 | EXPORT_SYMBOL(key_create_or_update); | |
857 | ||
858 | /*****************************************************************************/ | |
859 | /* | |
860 | * update a key | |
861 | */ | |
664cceb0 | 862 | int key_update(key_ref_t key_ref, const void *payload, size_t plen) |
1da177e4 | 863 | { |
664cceb0 | 864 | struct key *key = key_ref_to_ptr(key_ref); |
1da177e4 LT |
865 | int ret; |
866 | ||
867 | key_check(key); | |
868 | ||
869 | /* the key must be writable */ | |
29db9190 DH |
870 | ret = key_permission(key_ref, KEY_WRITE); |
871 | if (ret < 0) | |
1da177e4 LT |
872 | goto error; |
873 | ||
874 | /* attempt to update it if supported */ | |
875 | ret = -EOPNOTSUPP; | |
876 | if (key->type->update) { | |
877 | down_write(&key->sem); | |
1da177e4 | 878 | |
29db9190 | 879 | ret = key->type->update(key, payload, plen); |
76d8aeab | 880 | if (ret == 0) |
1da177e4 | 881 | /* updating a negative key instantiates it */ |
76d8aeab | 882 | clear_bit(KEY_FLAG_NEGATIVE, &key->flags); |
1da177e4 LT |
883 | |
884 | up_write(&key->sem); | |
885 | } | |
886 | ||
887 | error: | |
888 | return ret; | |
889 | ||
890 | } /* end key_update() */ | |
891 | ||
892 | EXPORT_SYMBOL(key_update); | |
893 | ||
1da177e4 LT |
894 | /*****************************************************************************/ |
895 | /* | |
896 | * revoke a key | |
897 | */ | |
898 | void key_revoke(struct key *key) | |
899 | { | |
900 | key_check(key); | |
901 | ||
902 | /* make sure no one's trying to change or use the key when we mark | |
903 | * it */ | |
904 | down_write(&key->sem); | |
76d8aeab | 905 | set_bit(KEY_FLAG_REVOKED, &key->flags); |
04c567d9 DH |
906 | |
907 | if (key->type->revoke) | |
908 | key->type->revoke(key); | |
909 | ||
1da177e4 LT |
910 | up_write(&key->sem); |
911 | ||
912 | } /* end key_revoke() */ | |
913 | ||
914 | EXPORT_SYMBOL(key_revoke); | |
915 | ||
916 | /*****************************************************************************/ | |
917 | /* | |
918 | * register a type of key | |
919 | */ | |
920 | int register_key_type(struct key_type *ktype) | |
921 | { | |
922 | struct key_type *p; | |
923 | int ret; | |
924 | ||
925 | ret = -EEXIST; | |
926 | down_write(&key_types_sem); | |
927 | ||
928 | /* disallow key types with the same name */ | |
929 | list_for_each_entry(p, &key_types_list, link) { | |
930 | if (strcmp(p->name, ktype->name) == 0) | |
931 | goto out; | |
932 | } | |
933 | ||
934 | /* store the type */ | |
935 | list_add(&ktype->link, &key_types_list); | |
936 | ret = 0; | |
937 | ||
938 | out: | |
939 | up_write(&key_types_sem); | |
940 | return ret; | |
941 | ||
942 | } /* end register_key_type() */ | |
943 | ||
944 | EXPORT_SYMBOL(register_key_type); | |
945 | ||
946 | /*****************************************************************************/ | |
947 | /* | |
948 | * unregister a type of key | |
949 | */ | |
950 | void unregister_key_type(struct key_type *ktype) | |
951 | { | |
952 | struct rb_node *_n; | |
953 | struct key *key; | |
954 | ||
955 | down_write(&key_types_sem); | |
956 | ||
957 | /* withdraw the key type */ | |
958 | list_del_init(&ktype->link); | |
959 | ||
76d8aeab | 960 | /* mark all the keys of this type dead */ |
1da177e4 LT |
961 | spin_lock(&key_serial_lock); |
962 | ||
963 | for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) { | |
964 | key = rb_entry(_n, struct key, serial_node); | |
965 | ||
76d8aeab DH |
966 | if (key->type == ktype) |
967 | key->type = &key_type_dead; | |
968 | } | |
969 | ||
970 | spin_unlock(&key_serial_lock); | |
971 | ||
972 | /* make sure everyone revalidates their keys */ | |
b2b18660 | 973 | synchronize_rcu(); |
76d8aeab DH |
974 | |
975 | /* we should now be able to destroy the payloads of all the keys of | |
976 | * this type with impunity */ | |
977 | spin_lock(&key_serial_lock); | |
1da177e4 | 978 | |
76d8aeab DH |
979 | for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) { |
980 | key = rb_entry(_n, struct key, serial_node); | |
1da177e4 | 981 | |
76d8aeab DH |
982 | if (key->type == ktype) { |
983 | if (ktype->destroy) | |
984 | ktype->destroy(key); | |
a7807a32 | 985 | memset(&key->payload, KEY_DESTROY, sizeof(key->payload)); |
76d8aeab | 986 | } |
1da177e4 LT |
987 | } |
988 | ||
989 | spin_unlock(&key_serial_lock); | |
990 | up_write(&key_types_sem); | |
991 | ||
992 | } /* end unregister_key_type() */ | |
993 | ||
994 | EXPORT_SYMBOL(unregister_key_type); | |
995 | ||
996 | /*****************************************************************************/ | |
997 | /* | |
998 | * initialise the key management stuff | |
999 | */ | |
1000 | void __init key_init(void) | |
1001 | { | |
1002 | /* allocate a slab in which we can store keys */ | |
1003 | key_jar = kmem_cache_create("key_jar", sizeof(struct key), | |
20c2df83 | 1004 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 LT |
1005 | |
1006 | /* add the special key types */ | |
1007 | list_add_tail(&key_type_keyring.link, &key_types_list); | |
1008 | list_add_tail(&key_type_dead.link, &key_types_list); | |
1009 | list_add_tail(&key_type_user.link, &key_types_list); | |
1010 | ||
1011 | /* record the root user tracking */ | |
1012 | rb_link_node(&root_key_user.node, | |
1013 | NULL, | |
1014 | &key_user_tree.rb_node); | |
1015 | ||
1016 | rb_insert_color(&root_key_user.node, | |
1017 | &key_user_tree); | |
1018 | ||
1019 | /* record root's user standard keyrings */ | |
1020 | key_check(&root_user_keyring); | |
1021 | key_check(&root_session_keyring); | |
1022 | ||
1023 | __key_insert_serial(&root_user_keyring); | |
1024 | __key_insert_serial(&root_session_keyring); | |
1025 | ||
1026 | keyring_publish_name(&root_user_keyring); | |
1027 | keyring_publish_name(&root_session_keyring); | |
1028 | ||
1029 | /* link the two root keyrings together */ | |
1030 | key_link(&root_session_keyring, &root_user_keyring); | |
76d8aeab | 1031 | |
1da177e4 | 1032 | } /* end key_init() */ |