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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 | * Get the key quota record for a user, allocating a new record if one doesn't |
61 | * already exist. |
62 | */ |
63 | struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns) |
64 | { |
65 | struct key_user *candidate = NULL, *user; |
66 | struct rb_node *parent = NULL; |
67 | struct rb_node **p; |
68 | |
69 | try_again: |
70 | p = &key_user_tree.rb_node; |
71 | spin_lock(&key_user_lock); |
72 | |
73 | /* search the tree for a user record with a matching UID */ |
74 | while (*p) { |
75 | parent = *p; |
76 | user = rb_entry(parent, struct key_user, node); |
77 | |
78 | if (uid < user->uid) |
79 | p = &(*p)->rb_left; |
80 | else if (uid > user->uid) |
81 | p = &(*p)->rb_right; |
82 | else if (user_ns < user->user_ns) |
83 | p = &(*p)->rb_left; |
84 | else if (user_ns > user->user_ns) |
85 | p = &(*p)->rb_right; |
86 | else |
87 | goto found; |
88 | } |
89 | |
90 | /* if we get here, we failed to find a match in the tree */ |
91 | if (!candidate) { |
92 | /* allocate a candidate user record if we don't already have |
93 | * one */ |
94 | spin_unlock(&key_user_lock); |
95 | |
96 | user = NULL; |
97 | candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL); |
98 | if (unlikely(!candidate)) |
99 | goto out; |
100 | |
101 | /* the allocation may have scheduled, so we need to repeat the |
102 | * search lest someone else added the record whilst we were |
103 | * asleep */ |
104 | goto try_again; |
105 | } |
106 | |
107 | /* if we get here, then the user record still hadn't appeared on the |
108 | * second pass - so we use the candidate record */ |
109 | atomic_set(&candidate->usage, 1); |
110 | atomic_set(&candidate->nkeys, 0); |
111 | atomic_set(&candidate->nikeys, 0); |
112 | candidate->uid = uid; |
113 | candidate->user_ns = get_user_ns(user_ns); |
114 | candidate->qnkeys = 0; |
115 | candidate->qnbytes = 0; |
116 | spin_lock_init(&candidate->lock); |
117 | mutex_init(&candidate->cons_lock); |
118 | |
119 | rb_link_node(&candidate->node, parent, p); |
120 | rb_insert_color(&candidate->node, &key_user_tree); |
121 | spin_unlock(&key_user_lock); |
122 | user = candidate; |
123 | goto out; |
124 | |
125 | /* okay - we found a user record for this UID */ |
126 | found: |
127 | atomic_inc(&user->usage); |
128 | spin_unlock(&key_user_lock); |
129 | kfree(candidate); |
130 | out: |
131 | return user; |
132 | } |
133 | |
134 | /* |
135 | * Dispose of a user structure |
136 | */ |
137 | void key_user_put(struct key_user *user) |
138 | { |
139 | if (atomic_dec_and_lock(&user->usage, &key_user_lock)) { |
140 | rb_erase(&user->node, &key_user_tree); |
141 | spin_unlock(&key_user_lock); |
142 | put_user_ns(user->user_ns); |
143 | |
144 | kfree(user); |
145 | } |
146 | } |
147 | |
148 | /* |
149 | * Allocate a serial number for a key. These are assigned randomly to avoid |
150 | * security issues through covert channel problems. |
151 | */ |
152 | static inline void key_alloc_serial(struct key *key) |
153 | { |
154 | struct rb_node *parent, **p; |
155 | struct key *xkey; |
156 | |
157 | /* propose a random serial number and look for a hole for it in the |
158 | * serial number tree */ |
159 | do { |
160 | get_random_bytes(&key->serial, sizeof(key->serial)); |
161 | |
162 | key->serial >>= 1; /* negative numbers are not permitted */ |
163 | } while (key->serial < 3); |
164 | |
165 | spin_lock(&key_serial_lock); |
166 | |
167 | attempt_insertion: |
168 | parent = NULL; |
169 | p = &key_serial_tree.rb_node; |
170 | |
171 | while (*p) { |
172 | parent = *p; |
173 | xkey = rb_entry(parent, struct key, serial_node); |
174 | |
175 | if (key->serial < xkey->serial) |
176 | p = &(*p)->rb_left; |
177 | else if (key->serial > xkey->serial) |
178 | p = &(*p)->rb_right; |
179 | else |
180 | goto serial_exists; |
181 | } |
182 | |
183 | /* we've found a suitable hole - arrange for this key to occupy it */ |
184 | rb_link_node(&key->serial_node, parent, p); |
185 | rb_insert_color(&key->serial_node, &key_serial_tree); |
186 | |
187 | spin_unlock(&key_serial_lock); |
188 | return; |
189 | |
190 | /* we found a key with the proposed serial number - walk the tree from |
191 | * that point looking for the next unused serial number */ |
192 | serial_exists: |
193 | for (;;) { |
194 | key->serial++; |
195 | if (key->serial < 3) { |
196 | key->serial = 3; |
197 | goto attempt_insertion; |
198 | } |
199 | |
200 | parent = rb_next(parent); |
201 | if (!parent) |
202 | goto attempt_insertion; |
203 | |
204 | xkey = rb_entry(parent, struct key, serial_node); |
205 | if (key->serial < xkey->serial) |
206 | goto attempt_insertion; |
207 | } |
208 | } |
209 | |
210 | /** |
211 | * key_alloc - Allocate a key of the specified type. |
212 | * @type: The type of key to allocate. |
213 | * @desc: The key description to allow the key to be searched out. |
214 | * @uid: The owner of the new key. |
215 | * @gid: The group ID for the new key's group permissions. |
216 | * @cred: The credentials specifying UID namespace. |
217 | * @perm: The permissions mask of the new key. |
218 | * @flags: Flags specifying quota properties. |
219 | * |
220 | * Allocate a key of the specified type with the attributes given. The key is |
221 | * returned in an uninstantiated state and the caller needs to instantiate the |
222 | * key before returning. |
223 | * |
224 | * The user's key count quota is updated to reflect the creation of the key and |
225 | * the user's key data quota has the default for the key type reserved. The |
226 | * instantiation function should amend this as necessary. If insufficient |
227 | * quota is available, -EDQUOT will be returned. |
228 | * |
229 | * The LSM security modules can prevent a key being created, in which case |
230 | * -EACCES will be returned. |
231 | * |
232 | * Returns a pointer to the new key if successful and an error code otherwise. |
233 | * |
234 | * Note that the caller needs to ensure the key type isn't uninstantiated. |
235 | * Internally this can be done by locking key_types_sem. Externally, this can |
236 | * be done by either never unregistering the key type, or making sure |
237 | * key_alloc() calls don't race with module unloading. |
238 | */ |
239 | struct key *key_alloc(struct key_type *type, const char *desc, |
240 | uid_t uid, gid_t gid, const struct cred *cred, |
241 | key_perm_t perm, unsigned long flags) |
242 | { |
243 | struct key_user *user = NULL; |
244 | struct key *key; |
245 | size_t desclen, quotalen; |
246 | int ret; |
247 | |
248 | key = ERR_PTR(-EINVAL); |
249 | if (!desc || !*desc) |
250 | goto error; |
251 | |
252 | desclen = strlen(desc) + 1; |
253 | quotalen = desclen + type->def_datalen; |
254 | |
255 | /* get hold of the key tracking for this user */ |
256 | user = key_user_lookup(uid, cred->user->user_ns); |
257 | if (!user) |
258 | goto no_memory_1; |
259 | |
260 | /* check that the user's quota permits allocation of another key and |
261 | * its description */ |
262 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { |
263 | unsigned maxkeys = (uid == 0) ? |
264 | key_quota_root_maxkeys : key_quota_maxkeys; |
265 | unsigned maxbytes = (uid == 0) ? |
266 | key_quota_root_maxbytes : key_quota_maxbytes; |
267 | |
268 | spin_lock(&user->lock); |
269 | if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) { |
270 | if (user->qnkeys + 1 >= maxkeys || |
271 | user->qnbytes + quotalen >= maxbytes || |
272 | user->qnbytes + quotalen < user->qnbytes) |
273 | goto no_quota; |
274 | } |
275 | |
276 | user->qnkeys++; |
277 | user->qnbytes += quotalen; |
278 | spin_unlock(&user->lock); |
279 | } |
280 | |
281 | /* allocate and initialise the key and its description */ |
282 | key = kmem_cache_alloc(key_jar, GFP_KERNEL); |
283 | if (!key) |
284 | goto no_memory_2; |
285 | |
286 | if (desc) { |
287 | key->description = kmemdup(desc, desclen, GFP_KERNEL); |
288 | if (!key->description) |
289 | goto no_memory_3; |
290 | } |
291 | |
292 | atomic_set(&key->usage, 1); |
293 | init_rwsem(&key->sem); |
294 | key->type = type; |
295 | key->user = user; |
296 | key->quotalen = quotalen; |
297 | key->datalen = type->def_datalen; |
298 | key->uid = uid; |
299 | key->gid = gid; |
300 | key->perm = perm; |
301 | key->flags = 0; |
302 | key->expiry = 0; |
303 | key->payload.data = NULL; |
304 | key->security = NULL; |
305 | |
306 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) |
307 | key->flags |= 1 << KEY_FLAG_IN_QUOTA; |
308 | |
309 | memset(&key->type_data, 0, sizeof(key->type_data)); |
310 | |
311 | #ifdef KEY_DEBUGGING |
312 | key->magic = KEY_DEBUG_MAGIC; |
313 | #endif |
314 | |
315 | /* let the security module know about the key */ |
316 | ret = security_key_alloc(key, cred, flags); |
317 | if (ret < 0) |
318 | goto security_error; |
319 | |
320 | /* publish the key by giving it a serial number */ |
321 | atomic_inc(&user->nkeys); |
322 | key_alloc_serial(key); |
323 | |
324 | error: |
325 | return key; |
326 | |
327 | security_error: |
328 | kfree(key->description); |
329 | kmem_cache_free(key_jar, key); |
330 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { |
331 | spin_lock(&user->lock); |
332 | user->qnkeys--; |
333 | user->qnbytes -= quotalen; |
334 | spin_unlock(&user->lock); |
335 | } |
336 | key_user_put(user); |
337 | key = ERR_PTR(ret); |
338 | goto error; |
339 | |
340 | no_memory_3: |
341 | kmem_cache_free(key_jar, key); |
342 | no_memory_2: |
343 | if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { |
344 | spin_lock(&user->lock); |
345 | user->qnkeys--; |
346 | user->qnbytes -= quotalen; |
347 | spin_unlock(&user->lock); |
348 | } |
349 | key_user_put(user); |
350 | no_memory_1: |
351 | key = ERR_PTR(-ENOMEM); |
352 | goto error; |
353 | |
354 | no_quota: |
355 | spin_unlock(&user->lock); |
356 | key_user_put(user); |
357 | key = ERR_PTR(-EDQUOT); |
358 | goto error; |
359 | } |
360 | EXPORT_SYMBOL(key_alloc); |
361 | |
362 | /** |
363 | * key_payload_reserve - Adjust data quota reservation for the key's payload |
364 | * @key: The key to make the reservation for. |
365 | * @datalen: The amount of data payload the caller now wants. |
366 | * |
367 | * Adjust the amount of the owning user's key data quota that a key reserves. |
368 | * If the amount is increased, then -EDQUOT may be returned if there isn't |
369 | * enough free quota available. |
370 | * |
371 | * If successful, 0 is returned. |
372 | */ |
373 | int key_payload_reserve(struct key *key, size_t datalen) |
374 | { |
375 | int delta = (int)datalen - key->datalen; |
376 | int ret = 0; |
377 | |
378 | key_check(key); |
379 | |
380 | /* contemplate the quota adjustment */ |
381 | if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) { |
382 | unsigned maxbytes = (key->user->uid == 0) ? |
383 | key_quota_root_maxbytes : key_quota_maxbytes; |
384 | |
385 | spin_lock(&key->user->lock); |
386 | |
387 | if (delta > 0 && |
388 | (key->user->qnbytes + delta >= maxbytes || |
389 | key->user->qnbytes + delta < key->user->qnbytes)) { |
390 | ret = -EDQUOT; |
391 | } |
392 | else { |
393 | key->user->qnbytes += delta; |
394 | key->quotalen += delta; |
395 | } |
396 | spin_unlock(&key->user->lock); |
397 | } |
398 | |
399 | /* change the recorded data length if that didn't generate an error */ |
400 | if (ret == 0) |
401 | key->datalen = datalen; |
402 | |
403 | return ret; |
404 | } |
405 | EXPORT_SYMBOL(key_payload_reserve); |
406 | |
407 | /* |
408 | * Instantiate a key and link it into the target keyring atomically. Must be |
409 | * called with the target keyring's semaphore writelocked. The target key's |
410 | * semaphore need not be locked as instantiation is serialised by |
411 | * key_construction_mutex. |
412 | */ |
413 | static int __key_instantiate_and_link(struct key *key, |
414 | const void *data, |
415 | size_t datalen, |
416 | struct key *keyring, |
417 | struct key *authkey, |
418 | unsigned long *_prealloc) |
419 | { |
420 | int ret, awaken; |
421 | |
422 | key_check(key); |
423 | key_check(keyring); |
424 | |
425 | awaken = 0; |
426 | ret = -EBUSY; |
427 | |
428 | mutex_lock(&key_construction_mutex); |
429 | |
430 | /* can't instantiate twice */ |
431 | if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { |
432 | /* instantiate the key */ |
433 | ret = key->type->instantiate(key, data, datalen); |
434 | |
435 | if (ret == 0) { |
436 | /* mark the key as being instantiated */ |
437 | atomic_inc(&key->user->nikeys); |
438 | set_bit(KEY_FLAG_INSTANTIATED, &key->flags); |
439 | |
440 | if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) |
441 | awaken = 1; |
442 | |
443 | /* and link it into the destination keyring */ |
444 | if (keyring) |
445 | __key_link(keyring, key, _prealloc); |
446 | |
447 | /* disable the authorisation key */ |
448 | if (authkey) |
449 | key_revoke(authkey); |
450 | } |
451 | } |
452 | |
453 | mutex_unlock(&key_construction_mutex); |
454 | |
455 | /* wake up anyone waiting for a key to be constructed */ |
456 | if (awaken) |
457 | wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); |
458 | |
459 | return ret; |
460 | } |
461 | |
462 | /** |
463 | * key_instantiate_and_link - Instantiate a key and link it into the keyring. |
464 | * @key: The key to instantiate. |
465 | * @data: The data to use to instantiate the keyring. |
466 | * @datalen: The length of @data. |
467 | * @keyring: Keyring to create a link in on success (or NULL). |
468 | * @authkey: The authorisation token permitting instantiation. |
469 | * |
470 | * Instantiate a key that's in the uninstantiated state using the provided data |
471 | * and, if successful, link it in to the destination keyring if one is |
472 | * supplied. |
473 | * |
474 | * If successful, 0 is returned, the authorisation token is revoked and anyone |
475 | * waiting for the key is woken up. If the key was already instantiated, |
476 | * -EBUSY will be returned. |
477 | */ |
478 | int key_instantiate_and_link(struct key *key, |
479 | const void *data, |
480 | size_t datalen, |
481 | struct key *keyring, |
482 | struct key *authkey) |
483 | { |
484 | unsigned long prealloc; |
485 | int ret; |
486 | |
487 | if (keyring) { |
488 | ret = __key_link_begin(keyring, key->type, key->description, |
489 | &prealloc); |
490 | if (ret < 0) |
491 | return ret; |
492 | } |
493 | |
494 | ret = __key_instantiate_and_link(key, data, datalen, keyring, authkey, |
495 | &prealloc); |
496 | |
497 | if (keyring) |
498 | __key_link_end(keyring, key->type, prealloc); |
499 | |
500 | return ret; |
501 | } |
502 | |
503 | EXPORT_SYMBOL(key_instantiate_and_link); |
504 | |
505 | /** |
506 | * key_negate_and_link - Negatively instantiate a key and link it into the keyring. |
507 | * @key: The key to instantiate. |
508 | * @timeout: The timeout on the negative key. |
509 | * @keyring: Keyring to create a link in on success (or NULL). |
510 | * @authkey: The authorisation token permitting instantiation. |
511 | * |
512 | * Negatively instantiate a key that's in the uninstantiated state and, if |
513 | * successful, set its timeout and link it in to the destination keyring if one |
514 | * is supplied. The key and any links to the key will be automatically garbage |
515 | * collected after the timeout expires. |
516 | * |
517 | * Negative keys are used to rate limit repeated request_key() calls by causing |
518 | * them to return -ENOKEY until the negative key expires. |
519 | * |
520 | * If successful, 0 is returned, the authorisation token is revoked and anyone |
521 | * waiting for the key is woken up. If the key was already instantiated, |
522 | * -EBUSY will be returned. |
523 | */ |
524 | int key_negate_and_link(struct key *key, |
525 | unsigned timeout, |
526 | struct key *keyring, |
527 | struct key *authkey) |
528 | { |
529 | unsigned long prealloc; |
530 | struct timespec now; |
531 | int ret, awaken, link_ret = 0; |
532 | |
533 | key_check(key); |
534 | key_check(keyring); |
535 | |
536 | awaken = 0; |
537 | ret = -EBUSY; |
538 | |
539 | if (keyring) |
540 | link_ret = __key_link_begin(keyring, key->type, |
541 | key->description, &prealloc); |
542 | |
543 | mutex_lock(&key_construction_mutex); |
544 | |
545 | /* can't instantiate twice */ |
546 | if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { |
547 | /* mark the key as being negatively instantiated */ |
548 | atomic_inc(&key->user->nikeys); |
549 | set_bit(KEY_FLAG_NEGATIVE, &key->flags); |
550 | set_bit(KEY_FLAG_INSTANTIATED, &key->flags); |
551 | now = current_kernel_time(); |
552 | key->expiry = now.tv_sec + timeout; |
553 | key_schedule_gc(key->expiry + key_gc_delay); |
554 | |
555 | if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) |
556 | awaken = 1; |
557 | |
558 | ret = 0; |
559 | |
560 | /* and link it into the destination keyring */ |
561 | if (keyring && link_ret == 0) |
562 | __key_link(keyring, key, &prealloc); |
563 | |
564 | /* disable the authorisation key */ |
565 | if (authkey) |
566 | key_revoke(authkey); |
567 | } |
568 | |
569 | mutex_unlock(&key_construction_mutex); |
570 | |
571 | if (keyring) |
572 | __key_link_end(keyring, key->type, prealloc); |
573 | |
574 | /* wake up anyone waiting for a key to be constructed */ |
575 | if (awaken) |
576 | wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); |
577 | |
578 | return ret == 0 ? link_ret : ret; |
579 | } |
580 | |
581 | EXPORT_SYMBOL(key_negate_and_link); |
582 | |
583 | /* |
584 | * Garbage collect keys in process context so that we don't have to disable |
585 | * interrupts all over the place. |
586 | * |
587 | * key_put() schedules this rather than trying to do the cleanup itself, which |
588 | * means key_put() doesn't have to sleep. |
589 | */ |
590 | static void key_cleanup(struct work_struct *work) |
591 | { |
592 | struct rb_node *_n; |
593 | struct key *key; |
594 | |
595 | go_again: |
596 | /* look for a dead key in the tree */ |
597 | spin_lock(&key_serial_lock); |
598 | |
599 | for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) { |
600 | key = rb_entry(_n, struct key, serial_node); |
601 | |
602 | if (atomic_read(&key->usage) == 0) |
603 | goto found_dead_key; |
604 | } |
605 | |
606 | spin_unlock(&key_serial_lock); |
607 | return; |
608 | |
609 | found_dead_key: |
610 | /* we found a dead key - once we've removed it from the tree, we can |
611 | * drop the lock */ |
612 | rb_erase(&key->serial_node, &key_serial_tree); |
613 | spin_unlock(&key_serial_lock); |
614 | |
615 | key_check(key); |
616 | |
617 | security_key_free(key); |
618 | |
619 | /* deal with the user's key tracking and quota */ |
620 | if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) { |
621 | spin_lock(&key->user->lock); |
622 | key->user->qnkeys--; |
623 | key->user->qnbytes -= key->quotalen; |
624 | spin_unlock(&key->user->lock); |
625 | } |
626 | |
627 | atomic_dec(&key->user->nkeys); |
628 | if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) |
629 | atomic_dec(&key->user->nikeys); |
630 | |
631 | key_user_put(key->user); |
632 | |
633 | /* now throw away the key memory */ |
634 | if (key->type->destroy) |
635 | key->type->destroy(key); |
636 | |
637 | kfree(key->description); |
638 | |
639 | #ifdef KEY_DEBUGGING |
640 | key->magic = KEY_DEBUG_MAGIC_X; |
641 | #endif |
642 | kmem_cache_free(key_jar, key); |
643 | |
644 | /* there may, of course, be more than one key to destroy */ |
645 | goto go_again; |
646 | } |
647 | |
648 | /** |
649 | * key_put - Discard a reference to a key. |
650 | * @key: The key to discard a reference from. |
651 | * |
652 | * Discard a reference to a key, and when all the references are gone, we |
653 | * schedule the cleanup task to come and pull it out of the tree in process |
654 | * context at some later time. |
655 | */ |
656 | void key_put(struct key *key) |
657 | { |
658 | if (key) { |
659 | key_check(key); |
660 | |
661 | if (atomic_dec_and_test(&key->usage)) |
662 | schedule_work(&key_cleanup_task); |
663 | } |
664 | } |
665 | EXPORT_SYMBOL(key_put); |
666 | |
667 | /* |
668 | * Find a key by its serial number. |
669 | */ |
670 | struct key *key_lookup(key_serial_t id) |
671 | { |
672 | struct rb_node *n; |
673 | struct key *key; |
674 | |
675 | spin_lock(&key_serial_lock); |
676 | |
677 | /* search the tree for the specified key */ |
678 | n = key_serial_tree.rb_node; |
679 | while (n) { |
680 | key = rb_entry(n, struct key, serial_node); |
681 | |
682 | if (id < key->serial) |
683 | n = n->rb_left; |
684 | else if (id > key->serial) |
685 | n = n->rb_right; |
686 | else |
687 | goto found; |
688 | } |
689 | |
690 | not_found: |
691 | key = ERR_PTR(-ENOKEY); |
692 | goto error; |
693 | |
694 | found: |
695 | /* pretend it doesn't exist if it is awaiting deletion */ |
696 | if (atomic_read(&key->usage) == 0) |
697 | goto not_found; |
698 | |
699 | /* this races with key_put(), but that doesn't matter since key_put() |
700 | * doesn't actually change the key |
701 | */ |
702 | atomic_inc(&key->usage); |
703 | |
704 | error: |
705 | spin_unlock(&key_serial_lock); |
706 | return key; |
707 | } |
708 | |
709 | /* |
710 | * Find and lock the specified key type against removal. |
711 | * |
712 | * We return with the sem read-locked if successful. If the type wasn't |
713 | * available -ENOKEY is returned instead. |
714 | */ |
715 | struct key_type *key_type_lookup(const char *type) |
716 | { |
717 | struct key_type *ktype; |
718 | |
719 | down_read(&key_types_sem); |
720 | |
721 | /* look up the key type to see if it's one of the registered kernel |
722 | * types */ |
723 | list_for_each_entry(ktype, &key_types_list, link) { |
724 | if (strcmp(ktype->name, type) == 0) |
725 | goto found_kernel_type; |
726 | } |
727 | |
728 | up_read(&key_types_sem); |
729 | ktype = ERR_PTR(-ENOKEY); |
730 | |
731 | found_kernel_type: |
732 | return ktype; |
733 | } |
734 | |
735 | /* |
736 | * Unlock a key type locked by key_type_lookup(). |
737 | */ |
738 | void key_type_put(struct key_type *ktype) |
739 | { |
740 | up_read(&key_types_sem); |
741 | } |
742 | |
743 | /* |
744 | * Attempt to update an existing key. |
745 | * |
746 | * The key is given to us with an incremented refcount that we need to discard |
747 | * if we get an error. |
748 | */ |
749 | static inline key_ref_t __key_update(key_ref_t key_ref, |
750 | const void *payload, size_t plen) |
751 | { |
752 | struct key *key = key_ref_to_ptr(key_ref); |
753 | int ret; |
754 | |
755 | /* need write permission on the key to update it */ |
756 | ret = key_permission(key_ref, KEY_WRITE); |
757 | if (ret < 0) |
758 | goto error; |
759 | |
760 | ret = -EEXIST; |
761 | if (!key->type->update) |
762 | goto error; |
763 | |
764 | down_write(&key->sem); |
765 | |
766 | ret = key->type->update(key, payload, plen); |
767 | if (ret == 0) |
768 | /* updating a negative key instantiates it */ |
769 | clear_bit(KEY_FLAG_NEGATIVE, &key->flags); |
770 | |
771 | up_write(&key->sem); |
772 | |
773 | if (ret < 0) |
774 | goto error; |
775 | out: |
776 | return key_ref; |
777 | |
778 | error: |
779 | key_put(key); |
780 | key_ref = ERR_PTR(ret); |
781 | goto out; |
782 | } |
783 | |
784 | /** |
785 | * key_create_or_update - Update or create and instantiate a key. |
786 | * @keyring_ref: A pointer to the destination keyring with possession flag. |
787 | * @type: The type of key. |
788 | * @description: The searchable description for the key. |
789 | * @payload: The data to use to instantiate or update the key. |
790 | * @plen: The length of @payload. |
791 | * @perm: The permissions mask for a new key. |
792 | * @flags: The quota flags for a new key. |
793 | * |
794 | * Search the destination keyring for a key of the same description and if one |
795 | * is found, update it, otherwise create and instantiate a new one and create a |
796 | * link to it from that keyring. |
797 | * |
798 | * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be |
799 | * concocted. |
800 | * |
801 | * Returns a pointer to the new key if successful, -ENODEV if the key type |
802 | * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the |
803 | * caller isn't permitted to modify the keyring or the LSM did not permit |
804 | * creation of the key. |
805 | * |
806 | * On success, the possession flag from the keyring ref will be tacked on to |
807 | * the key ref before it is returned. |
808 | */ |
809 | key_ref_t key_create_or_update(key_ref_t keyring_ref, |
810 | const char *type, |
811 | const char *description, |
812 | const void *payload, |
813 | size_t plen, |
814 | key_perm_t perm, |
815 | unsigned long flags) |
816 | { |
817 | unsigned long prealloc; |
818 | const struct cred *cred = current_cred(); |
819 | struct key_type *ktype; |
820 | struct key *keyring, *key = NULL; |
821 | key_ref_t key_ref; |
822 | int ret; |
823 | |
824 | /* look up the key type to see if it's one of the registered kernel |
825 | * types */ |
826 | ktype = key_type_lookup(type); |
827 | if (IS_ERR(ktype)) { |
828 | key_ref = ERR_PTR(-ENODEV); |
829 | goto error; |
830 | } |
831 | |
832 | key_ref = ERR_PTR(-EINVAL); |
833 | if (!ktype->match || !ktype->instantiate) |
834 | goto error_2; |
835 | |
836 | keyring = key_ref_to_ptr(keyring_ref); |
837 | |
838 | key_check(keyring); |
839 | |
840 | key_ref = ERR_PTR(-ENOTDIR); |
841 | if (keyring->type != &key_type_keyring) |
842 | goto error_2; |
843 | |
844 | ret = __key_link_begin(keyring, ktype, description, &prealloc); |
845 | if (ret < 0) |
846 | goto error_2; |
847 | |
848 | /* if we're going to allocate a new key, we're going to have |
849 | * to modify the keyring */ |
850 | ret = key_permission(keyring_ref, KEY_WRITE); |
851 | if (ret < 0) { |
852 | key_ref = ERR_PTR(ret); |
853 | goto error_3; |
854 | } |
855 | |
856 | /* if it's possible to update this type of key, search for an existing |
857 | * key of the same type and description in the destination keyring and |
858 | * update that instead if possible |
859 | */ |
860 | if (ktype->update) { |
861 | key_ref = __keyring_search_one(keyring_ref, ktype, description, |
862 | 0); |
863 | if (!IS_ERR(key_ref)) |
864 | goto found_matching_key; |
865 | } |
866 | |
867 | /* if the client doesn't provide, decide on the permissions we want */ |
868 | if (perm == KEY_PERM_UNDEF) { |
869 | perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR; |
870 | perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR; |
871 | |
872 | if (ktype->read) |
873 | perm |= KEY_POS_READ | KEY_USR_READ; |
874 | |
875 | if (ktype == &key_type_keyring || ktype->update) |
876 | perm |= KEY_USR_WRITE; |
877 | } |
878 | |
879 | /* allocate a new key */ |
880 | key = key_alloc(ktype, description, cred->fsuid, cred->fsgid, cred, |
881 | perm, flags); |
882 | if (IS_ERR(key)) { |
883 | key_ref = ERR_CAST(key); |
884 | goto error_3; |
885 | } |
886 | |
887 | /* instantiate it and link it into the target keyring */ |
888 | ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL, |
889 | &prealloc); |
890 | if (ret < 0) { |
891 | key_put(key); |
892 | key_ref = ERR_PTR(ret); |
893 | goto error_3; |
894 | } |
895 | |
896 | key_ref = make_key_ref(key, is_key_possessed(keyring_ref)); |
897 | |
898 | error_3: |
899 | __key_link_end(keyring, ktype, prealloc); |
900 | error_2: |
901 | key_type_put(ktype); |
902 | error: |
903 | return key_ref; |
904 | |
905 | found_matching_key: |
906 | /* we found a matching key, so we're going to try to update it |
907 | * - we can drop the locks first as we have the key pinned |
908 | */ |
909 | __key_link_end(keyring, ktype, prealloc); |
910 | key_type_put(ktype); |
911 | |
912 | key_ref = __key_update(key_ref, payload, plen); |
913 | goto error; |
914 | } |
915 | EXPORT_SYMBOL(key_create_or_update); |
916 | |
917 | /** |
918 | * key_update - Update a key's contents. |
919 | * @key_ref: The pointer (plus possession flag) to the key. |
920 | * @payload: The data to be used to update the key. |
921 | * @plen: The length of @payload. |
922 | * |
923 | * Attempt to update the contents of a key with the given payload data. The |
924 | * caller must be granted Write permission on the key. Negative keys can be |
925 | * instantiated by this method. |
926 | * |
927 | * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key |
928 | * type does not support updating. The key type may return other errors. |
929 | */ |
930 | int key_update(key_ref_t key_ref, const void *payload, size_t plen) |
931 | { |
932 | struct key *key = key_ref_to_ptr(key_ref); |
933 | int ret; |
934 | |
935 | key_check(key); |
936 | |
937 | /* the key must be writable */ |
938 | ret = key_permission(key_ref, KEY_WRITE); |
939 | if (ret < 0) |
940 | goto error; |
941 | |
942 | /* attempt to update it if supported */ |
943 | ret = -EOPNOTSUPP; |
944 | if (key->type->update) { |
945 | down_write(&key->sem); |
946 | |
947 | ret = key->type->update(key, payload, plen); |
948 | if (ret == 0) |
949 | /* updating a negative key instantiates it */ |
950 | clear_bit(KEY_FLAG_NEGATIVE, &key->flags); |
951 | |
952 | up_write(&key->sem); |
953 | } |
954 | |
955 | error: |
956 | return ret; |
957 | } |
958 | EXPORT_SYMBOL(key_update); |
959 | |
960 | /** |
961 | * key_revoke - Revoke a key. |
962 | * @key: The key to be revoked. |
963 | * |
964 | * Mark a key as being revoked and ask the type to free up its resources. The |
965 | * revocation timeout is set and the key and all its links will be |
966 | * automatically garbage collected after key_gc_delay amount of time if they |
967 | * are not manually dealt with first. |
968 | */ |
969 | void key_revoke(struct key *key) |
970 | { |
971 | struct timespec now; |
972 | time_t time; |
973 | |
974 | key_check(key); |
975 | |
976 | /* make sure no one's trying to change or use the key when we mark it |
977 | * - we tell lockdep that we might nest because we might be revoking an |
978 | * authorisation key whilst holding the sem on a key we've just |
979 | * instantiated |
980 | */ |
981 | down_write_nested(&key->sem, 1); |
982 | if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) && |
983 | key->type->revoke) |
984 | key->type->revoke(key); |
985 | |
986 | /* set the death time to no more than the expiry time */ |
987 | now = current_kernel_time(); |
988 | time = now.tv_sec; |
989 | if (key->revoked_at == 0 || key->revoked_at > time) { |
990 | key->revoked_at = time; |
991 | key_schedule_gc(key->revoked_at + key_gc_delay); |
992 | } |
993 | |
994 | up_write(&key->sem); |
995 | } |
996 | EXPORT_SYMBOL(key_revoke); |
997 | |
998 | /** |
999 | * register_key_type - Register a type of key. |
1000 | * @ktype: The new key type. |
1001 | * |
1002 | * Register a new key type. |
1003 | * |
1004 | * Returns 0 on success or -EEXIST if a type of this name already exists. |
1005 | */ |
1006 | int register_key_type(struct key_type *ktype) |
1007 | { |
1008 | struct key_type *p; |
1009 | int ret; |
1010 | |
1011 | ret = -EEXIST; |
1012 | down_write(&key_types_sem); |
1013 | |
1014 | /* disallow key types with the same name */ |
1015 | list_for_each_entry(p, &key_types_list, link) { |
1016 | if (strcmp(p->name, ktype->name) == 0) |
1017 | goto out; |
1018 | } |
1019 | |
1020 | /* store the type */ |
1021 | list_add(&ktype->link, &key_types_list); |
1022 | ret = 0; |
1023 | |
1024 | out: |
1025 | up_write(&key_types_sem); |
1026 | return ret; |
1027 | } |
1028 | EXPORT_SYMBOL(register_key_type); |
1029 | |
1030 | /** |
1031 | * unregister_key_type - Unregister a type of key. |
1032 | * @ktype: The key type. |
1033 | * |
1034 | * Unregister a key type and mark all the extant keys of this type as dead. |
1035 | * Those keys of this type are then destroyed to get rid of their payloads and |
1036 | * they and their links will be garbage collected as soon as possible. |
1037 | */ |
1038 | void unregister_key_type(struct key_type *ktype) |
1039 | { |
1040 | struct rb_node *_n; |
1041 | struct key *key; |
1042 | |
1043 | down_write(&key_types_sem); |
1044 | |
1045 | /* withdraw the key type */ |
1046 | list_del_init(&ktype->link); |
1047 | |
1048 | /* mark all the keys of this type dead */ |
1049 | spin_lock(&key_serial_lock); |
1050 | |
1051 | for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) { |
1052 | key = rb_entry(_n, struct key, serial_node); |
1053 | |
1054 | if (key->type == ktype) { |
1055 | key->type = &key_type_dead; |
1056 | set_bit(KEY_FLAG_DEAD, &key->flags); |
1057 | } |
1058 | } |
1059 | |
1060 | spin_unlock(&key_serial_lock); |
1061 | |
1062 | /* make sure everyone revalidates their keys */ |
1063 | synchronize_rcu(); |
1064 | |
1065 | /* we should now be able to destroy the payloads of all the keys of |
1066 | * this type with impunity */ |
1067 | spin_lock(&key_serial_lock); |
1068 | |
1069 | for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) { |
1070 | key = rb_entry(_n, struct key, serial_node); |
1071 | |
1072 | if (key->type == ktype) { |
1073 | if (ktype->destroy) |
1074 | ktype->destroy(key); |
1075 | memset(&key->payload, KEY_DESTROY, sizeof(key->payload)); |
1076 | } |
1077 | } |
1078 | |
1079 | spin_unlock(&key_serial_lock); |
1080 | up_write(&key_types_sem); |
1081 | |
1082 | key_schedule_gc(0); |
1083 | } |
1084 | EXPORT_SYMBOL(unregister_key_type); |
1085 | |
1086 | /* |
1087 | * Initialise the key management state. |
1088 | */ |
1089 | void __init key_init(void) |
1090 | { |
1091 | /* allocate a slab in which we can store keys */ |
1092 | key_jar = kmem_cache_create("key_jar", sizeof(struct key), |
1093 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1094 | |
1095 | /* add the special key types */ |
1096 | list_add_tail(&key_type_keyring.link, &key_types_list); |
1097 | list_add_tail(&key_type_dead.link, &key_types_list); |
1098 | list_add_tail(&key_type_user.link, &key_types_list); |
1099 | |
1100 | /* record the root user tracking */ |
1101 | rb_link_node(&root_key_user.node, |
1102 | NULL, |
1103 | &key_user_tree.rb_node); |
1104 | |
1105 | rb_insert_color(&root_key_user.node, |
1106 | &key_user_tree); |
1107 | } |
1108 |
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