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KEYS: Merge the type-specific data with the payload data
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76181c13 1/* Basic authentication token and access key management
1da177e4 2 *
69664cf1 3 * Copyright (C) 2004-2008 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
8bc16dea 23struct kmem_cache *key_jar;
1da177e4
LT
24struct rb_root key_serial_tree; /* tree of keys indexed by serial */
25DEFINE_SPINLOCK(key_serial_lock);
26
27struct rb_root key_user_tree; /* tree of quota records indexed by UID */
28DEFINE_SPINLOCK(key_user_lock);
29
738c5d19
SD
30unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
31unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
0b77f5bf
DH
32unsigned int key_quota_maxkeys = 200; /* general key count quota */
33unsigned int key_quota_maxbytes = 20000; /* general key space quota */
34
1da177e4
LT
35static LIST_HEAD(key_types_list);
36static DECLARE_RWSEM(key_types_sem);
37
973c9f4f 38/* We serialise key instantiation and link */
76181c13 39DEFINE_MUTEX(key_construction_mutex);
1da177e4 40
1da177e4
LT
41#ifdef KEY_DEBUGGING
42void __key_check(const struct key *key)
43{
44 printk("__key_check: key %p {%08x} should be {%08x}\n",
45 key, key->magic, KEY_DEBUG_MAGIC);
46 BUG();
47}
48#endif
49
1da177e4 50/*
973c9f4f
DH
51 * Get the key quota record for a user, allocating a new record if one doesn't
52 * already exist.
1da177e4 53 */
9a56c2db 54struct key_user *key_user_lookup(kuid_t uid)
1da177e4
LT
55{
56 struct key_user *candidate = NULL, *user;
57 struct rb_node *parent = NULL;
58 struct rb_node **p;
59
973c9f4f 60try_again:
1da177e4
LT
61 p = &key_user_tree.rb_node;
62 spin_lock(&key_user_lock);
63
64 /* search the tree for a user record with a matching UID */
65 while (*p) {
66 parent = *p;
67 user = rb_entry(parent, struct key_user, node);
68
9a56c2db 69 if (uid_lt(uid, user->uid))
1da177e4 70 p = &(*p)->rb_left;
9a56c2db 71 else if (uid_gt(uid, user->uid))
1d1e9756 72 p = &(*p)->rb_right;
1da177e4
LT
73 else
74 goto found;
75 }
76
77 /* if we get here, we failed to find a match in the tree */
78 if (!candidate) {
79 /* allocate a candidate user record if we don't already have
80 * one */
81 spin_unlock(&key_user_lock);
82
83 user = NULL;
84 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
85 if (unlikely(!candidate))
86 goto out;
87
88 /* the allocation may have scheduled, so we need to repeat the
89 * search lest someone else added the record whilst we were
90 * asleep */
91 goto try_again;
92 }
93
94 /* if we get here, then the user record still hadn't appeared on the
95 * second pass - so we use the candidate record */
96 atomic_set(&candidate->usage, 1);
97 atomic_set(&candidate->nkeys, 0);
98 atomic_set(&candidate->nikeys, 0);
99 candidate->uid = uid;
100 candidate->qnkeys = 0;
101 candidate->qnbytes = 0;
102 spin_lock_init(&candidate->lock);
76181c13 103 mutex_init(&candidate->cons_lock);
1da177e4
LT
104
105 rb_link_node(&candidate->node, parent, p);
106 rb_insert_color(&candidate->node, &key_user_tree);
107 spin_unlock(&key_user_lock);
108 user = candidate;
109 goto out;
110
111 /* okay - we found a user record for this UID */
973c9f4f 112found:
1da177e4
LT
113 atomic_inc(&user->usage);
114 spin_unlock(&key_user_lock);
a7f988ba 115 kfree(candidate);
973c9f4f 116out:
1da177e4 117 return user;
a8b17ed0 118}
1da177e4 119
1da177e4 120/*
973c9f4f 121 * Dispose of a user structure
1da177e4
LT
122 */
123void key_user_put(struct key_user *user)
124{
125 if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
126 rb_erase(&user->node, &key_user_tree);
127 spin_unlock(&key_user_lock);
128
129 kfree(user);
130 }
a8b17ed0 131}
1da177e4 132
1da177e4 133/*
973c9f4f
DH
134 * Allocate a serial number for a key. These are assigned randomly to avoid
135 * security issues through covert channel problems.
1da177e4
LT
136 */
137static inline void key_alloc_serial(struct key *key)
138{
139 struct rb_node *parent, **p;
140 struct key *xkey;
141
e51f6d34 142 /* propose a random serial number and look for a hole for it in the
1da177e4 143 * serial number tree */
e51f6d34
ML
144 do {
145 get_random_bytes(&key->serial, sizeof(key->serial));
146
147 key->serial >>= 1; /* negative numbers are not permitted */
148 } while (key->serial < 3);
149
150 spin_lock(&key_serial_lock);
1da177e4 151
9ad0830f 152attempt_insertion:
1da177e4
LT
153 parent = NULL;
154 p = &key_serial_tree.rb_node;
155
156 while (*p) {
157 parent = *p;
158 xkey = rb_entry(parent, struct key, serial_node);
159
160 if (key->serial < xkey->serial)
161 p = &(*p)->rb_left;
162 else if (key->serial > xkey->serial)
163 p = &(*p)->rb_right;
164 else
165 goto serial_exists;
166 }
9ad0830f
DH
167
168 /* we've found a suitable hole - arrange for this key to occupy it */
169 rb_link_node(&key->serial_node, parent, p);
170 rb_insert_color(&key->serial_node, &key_serial_tree);
171
172 spin_unlock(&key_serial_lock);
173 return;
1da177e4
LT
174
175 /* we found a key with the proposed serial number - walk the tree from
176 * that point looking for the next unused serial number */
e51f6d34 177serial_exists:
1da177e4 178 for (;;) {
e51f6d34 179 key->serial++;
9ad0830f
DH
180 if (key->serial < 3) {
181 key->serial = 3;
182 goto attempt_insertion;
183 }
1da177e4
LT
184
185 parent = rb_next(parent);
186 if (!parent)
9ad0830f 187 goto attempt_insertion;
1da177e4
LT
188
189 xkey = rb_entry(parent, struct key, serial_node);
190 if (key->serial < xkey->serial)
9ad0830f 191 goto attempt_insertion;
1da177e4 192 }
a8b17ed0 193}
1da177e4 194
973c9f4f
DH
195/**
196 * key_alloc - Allocate a key of the specified type.
197 * @type: The type of key to allocate.
198 * @desc: The key description to allow the key to be searched out.
199 * @uid: The owner of the new key.
200 * @gid: The group ID for the new key's group permissions.
201 * @cred: The credentials specifying UID namespace.
202 * @perm: The permissions mask of the new key.
203 * @flags: Flags specifying quota properties.
204 *
205 * Allocate a key of the specified type with the attributes given. The key is
206 * returned in an uninstantiated state and the caller needs to instantiate the
207 * key before returning.
208 *
209 * The user's key count quota is updated to reflect the creation of the key and
210 * the user's key data quota has the default for the key type reserved. The
211 * instantiation function should amend this as necessary. If insufficient
212 * quota is available, -EDQUOT will be returned.
213 *
214 * The LSM security modules can prevent a key being created, in which case
215 * -EACCES will be returned.
216 *
217 * Returns a pointer to the new key if successful and an error code otherwise.
218 *
219 * Note that the caller needs to ensure the key type isn't uninstantiated.
220 * Internally this can be done by locking key_types_sem. Externally, this can
221 * be done by either never unregistering the key type, or making sure
222 * key_alloc() calls don't race with module unloading.
1da177e4
LT
223 */
224struct key *key_alloc(struct key_type *type, const char *desc,
9a56c2db 225 kuid_t uid, kgid_t gid, const struct cred *cred,
7e047ef5 226 key_perm_t perm, unsigned long flags)
1da177e4
LT
227{
228 struct key_user *user = NULL;
229 struct key *key;
230 size_t desclen, quotalen;
29db9190 231 int ret;
1da177e4
LT
232
233 key = ERR_PTR(-EINVAL);
234 if (!desc || !*desc)
235 goto error;
236
b9fffa38
DH
237 if (type->vet_description) {
238 ret = type->vet_description(desc);
239 if (ret < 0) {
240 key = ERR_PTR(ret);
241 goto error;
242 }
243 }
244
16feef43
DH
245 desclen = strlen(desc);
246 quotalen = desclen + 1 + type->def_datalen;
1da177e4
LT
247
248 /* get hold of the key tracking for this user */
9a56c2db 249 user = key_user_lookup(uid);
1da177e4
LT
250 if (!user)
251 goto no_memory_1;
252
253 /* check that the user's quota permits allocation of another key and
254 * its description */
7e047ef5 255 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
9a56c2db 256 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
0b77f5bf 257 key_quota_root_maxkeys : key_quota_maxkeys;
9a56c2db 258 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
0b77f5bf
DH
259 key_quota_root_maxbytes : key_quota_maxbytes;
260
1da177e4 261 spin_lock(&user->lock);
7e047ef5 262 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
0b77f5bf
DH
263 if (user->qnkeys + 1 >= maxkeys ||
264 user->qnbytes + quotalen >= maxbytes ||
265 user->qnbytes + quotalen < user->qnbytes)
7e047ef5
DH
266 goto no_quota;
267 }
1da177e4
LT
268
269 user->qnkeys++;
270 user->qnbytes += quotalen;
271 spin_unlock(&user->lock);
272 }
273
274 /* allocate and initialise the key and its description */
2480f57f 275 key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
1da177e4
LT
276 if (!key)
277 goto no_memory_2;
278
5057975a
DC
279 key->index_key.desc_len = desclen;
280 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
27720e75 281 if (!key->index_key.description)
5057975a 282 goto no_memory_3;
1da177e4
LT
283
284 atomic_set(&key->usage, 1);
1da177e4 285 init_rwsem(&key->sem);
7845bc39 286 lockdep_set_class(&key->sem, &type->lock_class);
16feef43 287 key->index_key.type = type;
1da177e4
LT
288 key->user = user;
289 key->quotalen = quotalen;
290 key->datalen = type->def_datalen;
291 key->uid = uid;
292 key->gid = gid;
293 key->perm = perm;
1da177e4 294
7e047ef5 295 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
76d8aeab 296 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
008643b8
DH
297 if (flags & KEY_ALLOC_TRUSTED)
298 key->flags |= 1 << KEY_FLAG_TRUSTED;
1da177e4 299
1da177e4
LT
300#ifdef KEY_DEBUGGING
301 key->magic = KEY_DEBUG_MAGIC;
302#endif
303
29db9190 304 /* let the security module know about the key */
d84f4f99 305 ret = security_key_alloc(key, cred, flags);
29db9190
DH
306 if (ret < 0)
307 goto security_error;
308
1da177e4
LT
309 /* publish the key by giving it a serial number */
310 atomic_inc(&user->nkeys);
311 key_alloc_serial(key);
312
29db9190 313error:
1da177e4
LT
314 return key;
315
29db9190
DH
316security_error:
317 kfree(key->description);
1da177e4 318 kmem_cache_free(key_jar, key);
7e047ef5 319 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
1da177e4
LT
320 spin_lock(&user->lock);
321 user->qnkeys--;
322 user->qnbytes -= quotalen;
323 spin_unlock(&user->lock);
324 }
325 key_user_put(user);
29db9190
DH
326 key = ERR_PTR(ret);
327 goto error;
328
329no_memory_3:
330 kmem_cache_free(key_jar, key);
331no_memory_2:
7e047ef5 332 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
29db9190
DH
333 spin_lock(&user->lock);
334 user->qnkeys--;
335 user->qnbytes -= quotalen;
336 spin_unlock(&user->lock);
337 }
338 key_user_put(user);
339no_memory_1:
1da177e4
LT
340 key = ERR_PTR(-ENOMEM);
341 goto error;
342
29db9190 343no_quota:
1da177e4
LT
344 spin_unlock(&user->lock);
345 key_user_put(user);
346 key = ERR_PTR(-EDQUOT);
347 goto error;
a8b17ed0 348}
1da177e4
LT
349EXPORT_SYMBOL(key_alloc);
350
973c9f4f
DH
351/**
352 * key_payload_reserve - Adjust data quota reservation for the key's payload
353 * @key: The key to make the reservation for.
354 * @datalen: The amount of data payload the caller now wants.
355 *
356 * Adjust the amount of the owning user's key data quota that a key reserves.
357 * If the amount is increased, then -EDQUOT may be returned if there isn't
358 * enough free quota available.
359 *
360 * If successful, 0 is returned.
1da177e4
LT
361 */
362int key_payload_reserve(struct key *key, size_t datalen)
363{
c5b60b5e 364 int delta = (int)datalen - key->datalen;
1da177e4
LT
365 int ret = 0;
366
367 key_check(key);
368
369 /* contemplate the quota adjustment */
76d8aeab 370 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
9a56c2db 371 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
0b77f5bf
DH
372 key_quota_root_maxbytes : key_quota_maxbytes;
373
1da177e4
LT
374 spin_lock(&key->user->lock);
375
376 if (delta > 0 &&
0b77f5bf
DH
377 (key->user->qnbytes + delta >= maxbytes ||
378 key->user->qnbytes + delta < key->user->qnbytes)) {
1da177e4
LT
379 ret = -EDQUOT;
380 }
381 else {
382 key->user->qnbytes += delta;
383 key->quotalen += delta;
384 }
385 spin_unlock(&key->user->lock);
386 }
387
388 /* change the recorded data length if that didn't generate an error */
389 if (ret == 0)
390 key->datalen = datalen;
391
392 return ret;
a8b17ed0 393}
1da177e4
LT
394EXPORT_SYMBOL(key_payload_reserve);
395
1da177e4 396/*
973c9f4f
DH
397 * Instantiate a key and link it into the target keyring atomically. Must be
398 * called with the target keyring's semaphore writelocked. The target key's
399 * semaphore need not be locked as instantiation is serialised by
400 * key_construction_mutex.
1da177e4
LT
401 */
402static int __key_instantiate_and_link(struct key *key,
cf7f601c 403 struct key_preparsed_payload *prep,
3e30148c 404 struct key *keyring,
f70e2e06 405 struct key *authkey,
b2a4df20 406 struct assoc_array_edit **_edit)
1da177e4
LT
407{
408 int ret, awaken;
409
410 key_check(key);
411 key_check(keyring);
412
413 awaken = 0;
414 ret = -EBUSY;
415
76181c13 416 mutex_lock(&key_construction_mutex);
1da177e4
LT
417
418 /* can't instantiate twice */
76d8aeab 419 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
1da177e4 420 /* instantiate the key */
cf7f601c 421 ret = key->type->instantiate(key, prep);
1da177e4
LT
422
423 if (ret == 0) {
424 /* mark the key as being instantiated */
1da177e4 425 atomic_inc(&key->user->nikeys);
76d8aeab 426 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
1da177e4 427
76d8aeab 428 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
1da177e4 429 awaken = 1;
1da177e4
LT
430
431 /* and link it into the destination keyring */
432 if (keyring)
b2a4df20 433 __key_link(key, _edit);
3e30148c
DH
434
435 /* disable the authorisation key */
d84f4f99
DH
436 if (authkey)
437 key_revoke(authkey);
7dfa0ca6
DH
438
439 if (prep->expiry != TIME_T_MAX) {
440 key->expiry = prep->expiry;
441 key_schedule_gc(prep->expiry + key_gc_delay);
442 }
1da177e4
LT
443 }
444 }
445
76181c13 446 mutex_unlock(&key_construction_mutex);
1da177e4
LT
447
448 /* wake up anyone waiting for a key to be constructed */
449 if (awaken)
76181c13 450 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
1da177e4
LT
451
452 return ret;
a8b17ed0 453}
1da177e4 454
973c9f4f
DH
455/**
456 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
457 * @key: The key to instantiate.
458 * @data: The data to use to instantiate the keyring.
459 * @datalen: The length of @data.
460 * @keyring: Keyring to create a link in on success (or NULL).
461 * @authkey: The authorisation token permitting instantiation.
462 *
463 * Instantiate a key that's in the uninstantiated state using the provided data
464 * and, if successful, link it in to the destination keyring if one is
465 * supplied.
466 *
467 * If successful, 0 is returned, the authorisation token is revoked and anyone
468 * waiting for the key is woken up. If the key was already instantiated,
469 * -EBUSY will be returned.
1da177e4
LT
470 */
471int key_instantiate_and_link(struct key *key,
472 const void *data,
473 size_t datalen,
3e30148c 474 struct key *keyring,
d84f4f99 475 struct key *authkey)
1da177e4 476{
cf7f601c 477 struct key_preparsed_payload prep;
b2a4df20 478 struct assoc_array_edit *edit;
1da177e4
LT
479 int ret;
480
cf7f601c
DH
481 memset(&prep, 0, sizeof(prep));
482 prep.data = data;
483 prep.datalen = datalen;
484 prep.quotalen = key->type->def_datalen;
7dfa0ca6 485 prep.expiry = TIME_T_MAX;
cf7f601c
DH
486 if (key->type->preparse) {
487 ret = key->type->preparse(&prep);
488 if (ret < 0)
489 goto error;
490 }
491
f70e2e06 492 if (keyring) {
b2a4df20 493 ret = __key_link_begin(keyring, &key->index_key, &edit);
f70e2e06 494 if (ret < 0)
4d8c0250 495 goto error;
f70e2e06 496 }
1da177e4 497
b2a4df20 498 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
1da177e4
LT
499
500 if (keyring)
b2a4df20 501 __key_link_end(keyring, &key->index_key, edit);
1da177e4 502
4d8c0250 503error:
cf7f601c
DH
504 if (key->type->preparse)
505 key->type->free_preparse(&prep);
1da177e4 506 return ret;
a8b17ed0 507}
1da177e4
LT
508
509EXPORT_SYMBOL(key_instantiate_and_link);
510
973c9f4f 511/**
fdd1b945 512 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
973c9f4f
DH
513 * @key: The key to instantiate.
514 * @timeout: The timeout on the negative key.
fdd1b945 515 * @error: The error to return when the key is hit.
973c9f4f
DH
516 * @keyring: Keyring to create a link in on success (or NULL).
517 * @authkey: The authorisation token permitting instantiation.
518 *
519 * Negatively instantiate a key that's in the uninstantiated state and, if
fdd1b945
DH
520 * successful, set its timeout and stored error and link it in to the
521 * destination keyring if one is supplied. The key and any links to the key
522 * will be automatically garbage collected after the timeout expires.
973c9f4f
DH
523 *
524 * Negative keys are used to rate limit repeated request_key() calls by causing
fdd1b945
DH
525 * them to return the stored error code (typically ENOKEY) until the negative
526 * key expires.
973c9f4f
DH
527 *
528 * If successful, 0 is returned, the authorisation token is revoked and anyone
529 * waiting for the key is woken up. If the key was already instantiated,
530 * -EBUSY will be returned.
1da177e4 531 */
fdd1b945 532int key_reject_and_link(struct key *key,
1da177e4 533 unsigned timeout,
fdd1b945 534 unsigned error,
3e30148c 535 struct key *keyring,
d84f4f99 536 struct key *authkey)
1da177e4 537{
b2a4df20 538 struct assoc_array_edit *edit;
1da177e4 539 struct timespec now;
f70e2e06 540 int ret, awaken, link_ret = 0;
1da177e4
LT
541
542 key_check(key);
543 key_check(keyring);
544
545 awaken = 0;
546 ret = -EBUSY;
547
548 if (keyring)
b2a4df20 549 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
1da177e4 550
76181c13 551 mutex_lock(&key_construction_mutex);
1da177e4
LT
552
553 /* can't instantiate twice */
76d8aeab 554 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
1da177e4 555 /* mark the key as being negatively instantiated */
1da177e4 556 atomic_inc(&key->user->nikeys);
146aa8b1 557 key->reject_error = -error;
74792b00 558 smp_wmb();
76d8aeab
DH
559 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
560 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
1da177e4
LT
561 now = current_kernel_time();
562 key->expiry = now.tv_sec + timeout;
c08ef808 563 key_schedule_gc(key->expiry + key_gc_delay);
1da177e4 564
76d8aeab 565 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
1da177e4 566 awaken = 1;
1da177e4 567
1da177e4
LT
568 ret = 0;
569
570 /* and link it into the destination keyring */
f70e2e06 571 if (keyring && link_ret == 0)
b2a4df20 572 __key_link(key, &edit);
3e30148c
DH
573
574 /* disable the authorisation key */
d84f4f99
DH
575 if (authkey)
576 key_revoke(authkey);
1da177e4
LT
577 }
578
76181c13 579 mutex_unlock(&key_construction_mutex);
1da177e4
LT
580
581 if (keyring)
b2a4df20 582 __key_link_end(keyring, &key->index_key, edit);
1da177e4
LT
583
584 /* wake up anyone waiting for a key to be constructed */
585 if (awaken)
76181c13 586 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
1da177e4 587
f70e2e06 588 return ret == 0 ? link_ret : ret;
a8b17ed0 589}
fdd1b945 590EXPORT_SYMBOL(key_reject_and_link);
1da177e4 591
973c9f4f
DH
592/**
593 * key_put - Discard a reference to a key.
594 * @key: The key to discard a reference from.
595 *
596 * Discard a reference to a key, and when all the references are gone, we
597 * schedule the cleanup task to come and pull it out of the tree in process
598 * context at some later time.
1da177e4
LT
599 */
600void key_put(struct key *key)
601{
602 if (key) {
603 key_check(key);
604
605 if (atomic_dec_and_test(&key->usage))
3b07e9ca 606 schedule_work(&key_gc_work);
1da177e4 607 }
a8b17ed0 608}
1da177e4
LT
609EXPORT_SYMBOL(key_put);
610
1da177e4 611/*
973c9f4f 612 * Find a key by its serial number.
1da177e4
LT
613 */
614struct key *key_lookup(key_serial_t id)
615{
616 struct rb_node *n;
617 struct key *key;
618
619 spin_lock(&key_serial_lock);
620
621 /* search the tree for the specified key */
622 n = key_serial_tree.rb_node;
623 while (n) {
624 key = rb_entry(n, struct key, serial_node);
625
626 if (id < key->serial)
627 n = n->rb_left;
628 else if (id > key->serial)
629 n = n->rb_right;
630 else
631 goto found;
632 }
633
973c9f4f 634not_found:
1da177e4
LT
635 key = ERR_PTR(-ENOKEY);
636 goto error;
637
973c9f4f 638found:
5593122e
DH
639 /* pretend it doesn't exist if it is awaiting deletion */
640 if (atomic_read(&key->usage) == 0)
1da177e4
LT
641 goto not_found;
642
643 /* this races with key_put(), but that doesn't matter since key_put()
644 * doesn't actually change the key
645 */
ccc3e6d9 646 __key_get(key);
1da177e4 647
973c9f4f 648error:
1da177e4
LT
649 spin_unlock(&key_serial_lock);
650 return key;
a8b17ed0 651}
1da177e4 652
1da177e4 653/*
973c9f4f
DH
654 * Find and lock the specified key type against removal.
655 *
656 * We return with the sem read-locked if successful. If the type wasn't
657 * available -ENOKEY is returned instead.
1da177e4
LT
658 */
659struct key_type *key_type_lookup(const char *type)
660{
661 struct key_type *ktype;
662
663 down_read(&key_types_sem);
664
665 /* look up the key type to see if it's one of the registered kernel
666 * types */
667 list_for_each_entry(ktype, &key_types_list, link) {
668 if (strcmp(ktype->name, type) == 0)
669 goto found_kernel_type;
670 }
671
672 up_read(&key_types_sem);
673 ktype = ERR_PTR(-ENOKEY);
674
973c9f4f 675found_kernel_type:
1da177e4 676 return ktype;
a8b17ed0 677}
1da177e4 678
59e6b9c1
BS
679void key_set_timeout(struct key *key, unsigned timeout)
680{
681 struct timespec now;
682 time_t expiry = 0;
683
684 /* make the changes with the locks held to prevent races */
685 down_write(&key->sem);
686
687 if (timeout > 0) {
688 now = current_kernel_time();
689 expiry = now.tv_sec + timeout;
690 }
691
692 key->expiry = expiry;
693 key_schedule_gc(key->expiry + key_gc_delay);
694
695 up_write(&key->sem);
696}
697EXPORT_SYMBOL_GPL(key_set_timeout);
698
1da177e4 699/*
973c9f4f 700 * Unlock a key type locked by key_type_lookup().
1da177e4
LT
701 */
702void key_type_put(struct key_type *ktype)
703{
704 up_read(&key_types_sem);
a8b17ed0 705}
1da177e4 706
1da177e4 707/*
973c9f4f
DH
708 * Attempt to update an existing key.
709 *
710 * The key is given to us with an incremented refcount that we need to discard
711 * if we get an error.
1da177e4 712 */
664cceb0 713static inline key_ref_t __key_update(key_ref_t key_ref,
cf7f601c 714 struct key_preparsed_payload *prep)
1da177e4 715{
664cceb0 716 struct key *key = key_ref_to_ptr(key_ref);
1da177e4
LT
717 int ret;
718
719 /* need write permission on the key to update it */
f5895943 720 ret = key_permission(key_ref, KEY_NEED_WRITE);
29db9190 721 if (ret < 0)
1da177e4
LT
722 goto error;
723
724 ret = -EEXIST;
725 if (!key->type->update)
726 goto error;
727
728 down_write(&key->sem);
729
cf7f601c 730 ret = key->type->update(key, prep);
76d8aeab 731 if (ret == 0)
1da177e4 732 /* updating a negative key instantiates it */
76d8aeab 733 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
1da177e4
LT
734
735 up_write(&key->sem);
736
737 if (ret < 0)
738 goto error;
664cceb0
DH
739out:
740 return key_ref;
1da177e4 741
664cceb0 742error:
1da177e4 743 key_put(key);
664cceb0 744 key_ref = ERR_PTR(ret);
1da177e4 745 goto out;
a8b17ed0 746}
1da177e4 747
973c9f4f
DH
748/**
749 * key_create_or_update - Update or create and instantiate a key.
750 * @keyring_ref: A pointer to the destination keyring with possession flag.
751 * @type: The type of key.
752 * @description: The searchable description for the key.
753 * @payload: The data to use to instantiate or update the key.
754 * @plen: The length of @payload.
755 * @perm: The permissions mask for a new key.
756 * @flags: The quota flags for a new key.
757 *
758 * Search the destination keyring for a key of the same description and if one
759 * is found, update it, otherwise create and instantiate a new one and create a
760 * link to it from that keyring.
761 *
762 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
763 * concocted.
764 *
765 * Returns a pointer to the new key if successful, -ENODEV if the key type
766 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
767 * caller isn't permitted to modify the keyring or the LSM did not permit
768 * creation of the key.
769 *
770 * On success, the possession flag from the keyring ref will be tacked on to
771 * the key ref before it is returned.
1da177e4 772 */
664cceb0
DH
773key_ref_t key_create_or_update(key_ref_t keyring_ref,
774 const char *type,
775 const char *description,
776 const void *payload,
777 size_t plen,
6b79ccb5 778 key_perm_t perm,
7e047ef5 779 unsigned long flags)
1da177e4 780{
16feef43
DH
781 struct keyring_index_key index_key = {
782 .description = description,
783 };
cf7f601c 784 struct key_preparsed_payload prep;
b2a4df20 785 struct assoc_array_edit *edit;
d84f4f99 786 const struct cred *cred = current_cred();
664cceb0 787 struct key *keyring, *key = NULL;
664cceb0 788 key_ref_t key_ref;
1da177e4
LT
789 int ret;
790
1da177e4
LT
791 /* look up the key type to see if it's one of the registered kernel
792 * types */
16feef43
DH
793 index_key.type = key_type_lookup(type);
794 if (IS_ERR(index_key.type)) {
664cceb0 795 key_ref = ERR_PTR(-ENODEV);
1da177e4
LT
796 goto error;
797 }
798
664cceb0 799 key_ref = ERR_PTR(-EINVAL);
c06cfb08 800 if (!index_key.type->instantiate ||
16feef43 801 (!index_key.description && !index_key.type->preparse))
cf7f601c 802 goto error_put_type;
1da177e4 803
664cceb0
DH
804 keyring = key_ref_to_ptr(keyring_ref);
805
806 key_check(keyring);
807
c3a9d654
DH
808 key_ref = ERR_PTR(-ENOTDIR);
809 if (keyring->type != &key_type_keyring)
cf7f601c
DH
810 goto error_put_type;
811
812 memset(&prep, 0, sizeof(prep));
813 prep.data = payload;
814 prep.datalen = plen;
16feef43 815 prep.quotalen = index_key.type->def_datalen;
008643b8 816 prep.trusted = flags & KEY_ALLOC_TRUSTED;
7dfa0ca6 817 prep.expiry = TIME_T_MAX;
16feef43
DH
818 if (index_key.type->preparse) {
819 ret = index_key.type->preparse(&prep);
cf7f601c
DH
820 if (ret < 0) {
821 key_ref = ERR_PTR(ret);
4d8c0250 822 goto error_free_prep;
cf7f601c 823 }
16feef43
DH
824 if (!index_key.description)
825 index_key.description = prep.description;
cf7f601c 826 key_ref = ERR_PTR(-EINVAL);
16feef43 827 if (!index_key.description)
cf7f601c
DH
828 goto error_free_prep;
829 }
16feef43 830 index_key.desc_len = strlen(index_key.description);
c3a9d654 831
008643b8
DH
832 key_ref = ERR_PTR(-EPERM);
833 if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags))
834 goto error_free_prep;
835 flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0;
836
b2a4df20 837 ret = __key_link_begin(keyring, &index_key, &edit);
cf7f601c
DH
838 if (ret < 0) {
839 key_ref = ERR_PTR(ret);
840 goto error_free_prep;
841 }
664cceb0
DH
842
843 /* if we're going to allocate a new key, we're going to have
844 * to modify the keyring */
f5895943 845 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
29db9190
DH
846 if (ret < 0) {
847 key_ref = ERR_PTR(ret);
cf7f601c 848 goto error_link_end;
29db9190 849 }
664cceb0 850
1d9b7d97
DH
851 /* if it's possible to update this type of key, search for an existing
852 * key of the same type and description in the destination keyring and
853 * update that instead if possible
1da177e4 854 */
16feef43 855 if (index_key.type->update) {
b2a4df20
DH
856 key_ref = find_key_to_update(keyring_ref, &index_key);
857 if (key_ref)
1d9b7d97
DH
858 goto found_matching_key;
859 }
1da177e4 860
6b79ccb5
AR
861 /* if the client doesn't provide, decide on the permissions we want */
862 if (perm == KEY_PERM_UNDEF) {
863 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
96b5c8fe 864 perm |= KEY_USR_VIEW;
1da177e4 865
16feef43 866 if (index_key.type->read)
96b5c8fe 867 perm |= KEY_POS_READ;
1da177e4 868
16feef43
DH
869 if (index_key.type == &key_type_keyring ||
870 index_key.type->update)
96b5c8fe 871 perm |= KEY_POS_WRITE;
6b79ccb5 872 }
1da177e4
LT
873
874 /* allocate a new key */
16feef43
DH
875 key = key_alloc(index_key.type, index_key.description,
876 cred->fsuid, cred->fsgid, cred, perm, flags);
1da177e4 877 if (IS_ERR(key)) {
e231c2ee 878 key_ref = ERR_CAST(key);
cf7f601c 879 goto error_link_end;
1da177e4
LT
880 }
881
882 /* instantiate it and link it into the target keyring */
b2a4df20 883 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
1da177e4
LT
884 if (ret < 0) {
885 key_put(key);
664cceb0 886 key_ref = ERR_PTR(ret);
cf7f601c 887 goto error_link_end;
1da177e4
LT
888 }
889
664cceb0
DH
890 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
891
cf7f601c 892error_link_end:
b2a4df20 893 __key_link_end(keyring, &index_key, edit);
cf7f601c 894error_free_prep:
16feef43
DH
895 if (index_key.type->preparse)
896 index_key.type->free_preparse(&prep);
cf7f601c 897error_put_type:
16feef43 898 key_type_put(index_key.type);
cf7f601c 899error:
664cceb0 900 return key_ref;
1da177e4
LT
901
902 found_matching_key:
903 /* we found a matching key, so we're going to try to update it
904 * - we can drop the locks first as we have the key pinned
905 */
b2a4df20 906 __key_link_end(keyring, &index_key, edit);
1da177e4 907
cf7f601c
DH
908 key_ref = __key_update(key_ref, &prep);
909 goto error_free_prep;
a8b17ed0 910}
1da177e4
LT
911EXPORT_SYMBOL(key_create_or_update);
912
973c9f4f
DH
913/**
914 * key_update - Update a key's contents.
915 * @key_ref: The pointer (plus possession flag) to the key.
916 * @payload: The data to be used to update the key.
917 * @plen: The length of @payload.
918 *
919 * Attempt to update the contents of a key with the given payload data. The
920 * caller must be granted Write permission on the key. Negative keys can be
921 * instantiated by this method.
922 *
923 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
924 * type does not support updating. The key type may return other errors.
1da177e4 925 */
664cceb0 926int key_update(key_ref_t key_ref, const void *payload, size_t plen)
1da177e4 927{
cf7f601c 928 struct key_preparsed_payload prep;
664cceb0 929 struct key *key = key_ref_to_ptr(key_ref);
1da177e4
LT
930 int ret;
931
932 key_check(key);
933
934 /* the key must be writable */
f5895943 935 ret = key_permission(key_ref, KEY_NEED_WRITE);
29db9190 936 if (ret < 0)
1da177e4
LT
937 goto error;
938
939 /* attempt to update it if supported */
940 ret = -EOPNOTSUPP;
cf7f601c
DH
941 if (!key->type->update)
942 goto error;
1da177e4 943
cf7f601c
DH
944 memset(&prep, 0, sizeof(prep));
945 prep.data = payload;
946 prep.datalen = plen;
947 prep.quotalen = key->type->def_datalen;
7dfa0ca6 948 prep.expiry = TIME_T_MAX;
cf7f601c
DH
949 if (key->type->preparse) {
950 ret = key->type->preparse(&prep);
951 if (ret < 0)
952 goto error;
1da177e4
LT
953 }
954
cf7f601c
DH
955 down_write(&key->sem);
956
957 ret = key->type->update(key, &prep);
958 if (ret == 0)
959 /* updating a negative key instantiates it */
960 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
961
962 up_write(&key->sem);
963
4d8c0250 964error:
cf7f601c
DH
965 if (key->type->preparse)
966 key->type->free_preparse(&prep);
1da177e4 967 return ret;
a8b17ed0 968}
1da177e4
LT
969EXPORT_SYMBOL(key_update);
970
973c9f4f
DH
971/**
972 * key_revoke - Revoke a key.
973 * @key: The key to be revoked.
974 *
975 * Mark a key as being revoked and ask the type to free up its resources. The
976 * revocation timeout is set and the key and all its links will be
977 * automatically garbage collected after key_gc_delay amount of time if they
978 * are not manually dealt with first.
1da177e4
LT
979 */
980void key_revoke(struct key *key)
981{
5d135440
DH
982 struct timespec now;
983 time_t time;
984
1da177e4
LT
985 key_check(key);
986
76181c13
DH
987 /* make sure no one's trying to change or use the key when we mark it
988 * - we tell lockdep that we might nest because we might be revoking an
989 * authorisation key whilst holding the sem on a key we've just
990 * instantiated
991 */
992 down_write_nested(&key->sem, 1);
993 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
994 key->type->revoke)
04c567d9
DH
995 key->type->revoke(key);
996
5d135440
DH
997 /* set the death time to no more than the expiry time */
998 now = current_kernel_time();
999 time = now.tv_sec;
1000 if (key->revoked_at == 0 || key->revoked_at > time) {
1001 key->revoked_at = time;
c08ef808 1002 key_schedule_gc(key->revoked_at + key_gc_delay);
5d135440
DH
1003 }
1004
1da177e4 1005 up_write(&key->sem);
a8b17ed0 1006}
1da177e4
LT
1007EXPORT_SYMBOL(key_revoke);
1008
fd75815f
DH
1009/**
1010 * key_invalidate - Invalidate a key.
1011 * @key: The key to be invalidated.
1012 *
1013 * Mark a key as being invalidated and have it cleaned up immediately. The key
1014 * is ignored by all searches and other operations from this point.
1015 */
1016void key_invalidate(struct key *key)
1017{
1018 kenter("%d", key_serial(key));
1019
1020 key_check(key);
1021
1022 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1023 down_write_nested(&key->sem, 1);
1024 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1025 key_schedule_gc_links();
1026 up_write(&key->sem);
1027 }
1028}
1029EXPORT_SYMBOL(key_invalidate);
1030
6a09d17b
DH
1031/**
1032 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1033 * @key: The key to be instantiated
1034 * @prep: The preparsed data to load.
1035 *
1036 * Instantiate a key from preparsed data. We assume we can just copy the data
1037 * in directly and clear the old pointers.
1038 *
1039 * This can be pointed to directly by the key type instantiate op pointer.
1040 */
1041int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1042{
1043 int ret;
1044
1045 pr_devel("==>%s()\n", __func__);
1046
1047 ret = key_payload_reserve(key, prep->quotalen);
1048 if (ret == 0) {
146aa8b1
DH
1049 rcu_assign_keypointer(key, prep->payload.data[0]);
1050 key->payload.data[1] = prep->payload.data[1];
1051 key->payload.data[2] = prep->payload.data[2];
1052 key->payload.data[3] = prep->payload.data[3];
1053 prep->payload.data[0] = NULL;
1054 prep->payload.data[1] = NULL;
1055 prep->payload.data[2] = NULL;
1056 prep->payload.data[3] = NULL;
6a09d17b
DH
1057 }
1058 pr_devel("<==%s() = %d\n", __func__, ret);
1059 return ret;
1060}
1061EXPORT_SYMBOL(generic_key_instantiate);
1062
973c9f4f
DH
1063/**
1064 * register_key_type - Register a type of key.
1065 * @ktype: The new key type.
1066 *
1067 * Register a new key type.
1068 *
1069 * Returns 0 on success or -EEXIST if a type of this name already exists.
1da177e4
LT
1070 */
1071int register_key_type(struct key_type *ktype)
1072{
1073 struct key_type *p;
1074 int ret;
1075
7845bc39
DH
1076 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1077
1da177e4
LT
1078 ret = -EEXIST;
1079 down_write(&key_types_sem);
1080
1081 /* disallow key types with the same name */
1082 list_for_each_entry(p, &key_types_list, link) {
1083 if (strcmp(p->name, ktype->name) == 0)
1084 goto out;
1085 }
1086
1087 /* store the type */
1088 list_add(&ktype->link, &key_types_list);
1eb1bcf5
DH
1089
1090 pr_notice("Key type %s registered\n", ktype->name);
1da177e4
LT
1091 ret = 0;
1092
973c9f4f 1093out:
1da177e4
LT
1094 up_write(&key_types_sem);
1095 return ret;
a8b17ed0 1096}
1da177e4
LT
1097EXPORT_SYMBOL(register_key_type);
1098
973c9f4f
DH
1099/**
1100 * unregister_key_type - Unregister a type of key.
1101 * @ktype: The key type.
1102 *
1103 * Unregister a key type and mark all the extant keys of this type as dead.
1104 * Those keys of this type are then destroyed to get rid of their payloads and
1105 * they and their links will be garbage collected as soon as possible.
1da177e4
LT
1106 */
1107void unregister_key_type(struct key_type *ktype)
1108{
1da177e4 1109 down_write(&key_types_sem);
1da177e4 1110 list_del_init(&ktype->link);
0c061b57
DH
1111 downgrade_write(&key_types_sem);
1112 key_gc_keytype(ktype);
1eb1bcf5 1113 pr_notice("Key type %s unregistered\n", ktype->name);
0c061b57 1114 up_read(&key_types_sem);
a8b17ed0 1115}
1da177e4
LT
1116EXPORT_SYMBOL(unregister_key_type);
1117
1da177e4 1118/*
973c9f4f 1119 * Initialise the key management state.
1da177e4
LT
1120 */
1121void __init key_init(void)
1122{
1123 /* allocate a slab in which we can store keys */
1124 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
20c2df83 1125 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1da177e4
LT
1126
1127 /* add the special key types */
1128 list_add_tail(&key_type_keyring.link, &key_types_list);
1129 list_add_tail(&key_type_dead.link, &key_types_list);
1130 list_add_tail(&key_type_user.link, &key_types_list);
9f6ed2ca 1131 list_add_tail(&key_type_logon.link, &key_types_list);
1da177e4
LT
1132
1133 /* record the root user tracking */
1134 rb_link_node(&root_key_user.node,
1135 NULL,
1136 &key_user_tree.rb_node);
1137
1138 rb_insert_color(&root_key_user.node,
1139 &key_user_tree);
a8b17ed0 1140}