blob: 80de8c3e9cc3ea49c79e6525b0ce17b22076ac3e [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* key.c: basic authentication token and access key management
2 *
David Howells3dccff82006-03-25 03:06:51 -08003 * Copyright (C) 2004-6 Red Hat, Inc. All Rights Reserved.
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 * 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>
Randy Dunlapa7807a32006-06-27 02:53:54 -070014#include <linux/poison.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/sched.h>
16#include <linux/slab.h>
David Howells29db9192005-10-30 15:02:44 -080017#include <linux/security.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/workqueue.h>
Michael LeMaye51f6d32006-06-26 00:24:54 -070019#include <linux/random.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/err.h>
21#include "internal.h"
22
23static kmem_cache_t *key_jar;
Linus Torvalds1da177e2005-04-16 15:20:36 -070024struct 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
30static LIST_HEAD(key_types_list);
31static DECLARE_RWSEM(key_types_sem);
32
33static void key_cleanup(void *data);
34static DECLARE_WORK(key_cleanup_task, key_cleanup, NULL);
35
36/* we serialise key instantiation and link */
37DECLARE_RWSEM(key_construction_sem);
38
39/* any key who's type gets unegistered will be re-typed to this */
Adrian Bunk1ae8f402006-01-06 00:11:25 -080040static struct key_type key_type_dead = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 .name = "dead",
42};
43
44#ifdef KEY_DEBUGGING
45void __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 */
58struct 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);
Jesper Juhla7f988b2005-11-07 01:01:35 -0800119 kfree(candidate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 out:
121 return user;
122
123} /* end key_user_lookup() */
124
125/*****************************************************************************/
126/*
127 * dispose of a user structure
128 */
129void 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 */
144static 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
Michael LeMaye51f6d32006-06-26 00:24:54 -0700173 * - these are assigned randomly to avoid security issues through covert
174 * channel problems
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 */
176static inline void key_alloc_serial(struct key *key)
177{
178 struct rb_node *parent, **p;
179 struct key *xkey;
180
Michael LeMaye51f6d32006-06-26 00:24:54 -0700181 /* propose a random serial number and look for a hole for it in the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 * serial number tree */
Michael LeMaye51f6d32006-06-26 00:24:54 -0700183 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);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190
191 parent = NULL;
192 p = &key_serial_tree.rb_node;
193
194 while (*p) {
195 parent = *p;
196 xkey = rb_entry(parent, struct key, serial_node);
197
198 if (key->serial < xkey->serial)
199 p = &(*p)->rb_left;
200 else if (key->serial > xkey->serial)
201 p = &(*p)->rb_right;
202 else
203 goto serial_exists;
204 }
205 goto insert_here;
206
207 /* we found a key with the proposed serial number - walk the tree from
208 * that point looking for the next unused serial number */
Michael LeMaye51f6d32006-06-26 00:24:54 -0700209serial_exists:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 for (;;) {
Michael LeMaye51f6d32006-06-26 00:24:54 -0700211 key->serial++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 if (key->serial < 2)
213 key->serial = 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214
David Woodhousefed306f2006-04-21 13:16:49 +0100215 if (!rb_parent(parent))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 p = &key_serial_tree.rb_node;
David Woodhousefed306f2006-04-21 13:16:49 +0100217 else if (rb_parent(parent)->rb_left == parent)
218 p = &(rb_parent(parent)->rb_left);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 else
David Woodhousefed306f2006-04-21 13:16:49 +0100220 p = &(rb_parent(parent)->rb_right);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221
222 parent = rb_next(parent);
223 if (!parent)
224 break;
225
226 xkey = rb_entry(parent, struct key, serial_node);
227 if (key->serial < xkey->serial)
228 goto insert_here;
229 }
230
231 /* we've found a suitable hole - arrange for this key to occupy it */
Michael LeMaye51f6d32006-06-26 00:24:54 -0700232insert_here:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 rb_link_node(&key->serial_node, parent, p);
234 rb_insert_color(&key->serial_node, &key_serial_tree);
235
236 spin_unlock(&key_serial_lock);
237
238} /* end key_alloc_serial() */
239
240/*****************************************************************************/
241/*
242 * allocate a key of the specified type
243 * - update the user's quota to reflect the existence of the key
David Howells8d9067b2006-01-06 00:11:24 -0800244 * - called from a key-type operation with key_types_sem read-locked by
245 * key_create_or_update()
246 * - this prevents unregistration of the key type
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 * - upon return the key is as yet uninstantiated; the caller needs to either
248 * instantiate the key or discard it before returning
249 */
250struct key *key_alloc(struct key_type *type, const char *desc,
Michael LeMayd7200242006-06-22 14:47:17 -0700251 uid_t uid, gid_t gid, struct task_struct *ctx,
David Howells7e047ef2006-06-26 00:24:50 -0700252 key_perm_t perm, unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253{
254 struct key_user *user = NULL;
255 struct key *key;
256 size_t desclen, quotalen;
David Howells29db9192005-10-30 15:02:44 -0800257 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258
259 key = ERR_PTR(-EINVAL);
260 if (!desc || !*desc)
261 goto error;
262
263 desclen = strlen(desc) + 1;
264 quotalen = desclen + type->def_datalen;
265
266 /* get hold of the key tracking for this user */
267 user = key_user_lookup(uid);
268 if (!user)
269 goto no_memory_1;
270
271 /* check that the user's quota permits allocation of another key and
272 * its description */
David Howells7e047ef2006-06-26 00:24:50 -0700273 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 spin_lock(&user->lock);
David Howells7e047ef2006-06-26 00:24:50 -0700275 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
276 if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
277 user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
278 )
279 goto no_quota;
280 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281
282 user->qnkeys++;
283 user->qnbytes += quotalen;
284 spin_unlock(&user->lock);
285 }
286
287 /* allocate and initialise the key and its description */
288 key = kmem_cache_alloc(key_jar, SLAB_KERNEL);
289 if (!key)
290 goto no_memory_2;
291
292 if (desc) {
293 key->description = kmalloc(desclen, GFP_KERNEL);
294 if (!key->description)
295 goto no_memory_3;
296
297 memcpy(key->description, desc, desclen);
298 }
299
300 atomic_set(&key->usage, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 init_rwsem(&key->sem);
302 key->type = type;
303 key->user = user;
304 key->quotalen = quotalen;
305 key->datalen = type->def_datalen;
306 key->uid = uid;
307 key->gid = gid;
308 key->perm = perm;
309 key->flags = 0;
310 key->expiry = 0;
311 key->payload.data = NULL;
David Howells29db9192005-10-30 15:02:44 -0800312 key->security = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313
David Howells7e047ef2006-06-26 00:24:50 -0700314 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
David Howells76d8aea2005-06-23 22:00:49 -0700315 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316
317 memset(&key->type_data, 0, sizeof(key->type_data));
318
319#ifdef KEY_DEBUGGING
320 key->magic = KEY_DEBUG_MAGIC;
321#endif
322
David Howells29db9192005-10-30 15:02:44 -0800323 /* let the security module know about the key */
David Howells7e047ef2006-06-26 00:24:50 -0700324 ret = security_key_alloc(key, ctx, flags);
David Howells29db9192005-10-30 15:02:44 -0800325 if (ret < 0)
326 goto security_error;
327
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 /* publish the key by giving it a serial number */
329 atomic_inc(&user->nkeys);
330 key_alloc_serial(key);
331
David Howells29db9192005-10-30 15:02:44 -0800332error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 return key;
334
David Howells29db9192005-10-30 15:02:44 -0800335security_error:
336 kfree(key->description);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 kmem_cache_free(key_jar, key);
David Howells7e047ef2006-06-26 00:24:50 -0700338 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 spin_lock(&user->lock);
340 user->qnkeys--;
341 user->qnbytes -= quotalen;
342 spin_unlock(&user->lock);
343 }
344 key_user_put(user);
David Howells29db9192005-10-30 15:02:44 -0800345 key = ERR_PTR(ret);
346 goto error;
347
348no_memory_3:
349 kmem_cache_free(key_jar, key);
350no_memory_2:
David Howells7e047ef2006-06-26 00:24:50 -0700351 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
David Howells29db9192005-10-30 15:02:44 -0800352 spin_lock(&user->lock);
353 user->qnkeys--;
354 user->qnbytes -= quotalen;
355 spin_unlock(&user->lock);
356 }
357 key_user_put(user);
358no_memory_1:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 key = ERR_PTR(-ENOMEM);
360 goto error;
361
David Howells29db9192005-10-30 15:02:44 -0800362no_quota:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 spin_unlock(&user->lock);
364 key_user_put(user);
365 key = ERR_PTR(-EDQUOT);
366 goto error;
367
368} /* end key_alloc() */
369
370EXPORT_SYMBOL(key_alloc);
371
372/*****************************************************************************/
373/*
374 * reserve an amount of quota for the key's payload
375 */
376int key_payload_reserve(struct key *key, size_t datalen)
377{
378 int delta = (int) datalen - key->datalen;
379 int ret = 0;
380
381 key_check(key);
382
383 /* contemplate the quota adjustment */
David Howells76d8aea2005-06-23 22:00:49 -0700384 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 spin_lock(&key->user->lock);
386
387 if (delta > 0 &&
388 key->user->qnbytes + delta > KEYQUOTA_MAX_BYTES
389 ) {
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} /* end key_payload_reserve() */
406
407EXPORT_SYMBOL(key_payload_reserve);
408
409/*****************************************************************************/
410/*
411 * instantiate a key and link it into the target keyring atomically
412 * - called with the target keyring's semaphore writelocked
413 */
414static int __key_instantiate_and_link(struct key *key,
415 const void *data,
416 size_t datalen,
David Howells3e301482005-06-23 22:00:56 -0700417 struct key *keyring,
418 struct key *instkey)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419{
420 int ret, awaken;
421
422 key_check(key);
423 key_check(keyring);
424
425 awaken = 0;
426 ret = -EBUSY;
427
428 down_write(&key_construction_sem);
429
430 /* can't instantiate twice */
David Howells76d8aea2005-06-23 22:00:49 -0700431 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 /* instantiate the key */
433 ret = key->type->instantiate(key, data, datalen);
434
435 if (ret == 0) {
436 /* mark the key as being instantiated */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 atomic_inc(&key->user->nikeys);
David Howells76d8aea2005-06-23 22:00:49 -0700438 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439
David Howells76d8aea2005-06-23 22:00:49 -0700440 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 awaken = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442
443 /* and link it into the destination keyring */
444 if (keyring)
445 ret = __key_link(keyring, key);
David Howells3e301482005-06-23 22:00:56 -0700446
447 /* disable the authorisation key */
448 if (instkey)
449 key_revoke(instkey);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 }
451 }
452
453 up_write(&key_construction_sem);
454
455 /* wake up anyone waiting for a key to be constructed */
456 if (awaken)
457 wake_up_all(&request_key_conswq);
458
459 return ret;
460
461} /* end __key_instantiate_and_link() */
462
463/*****************************************************************************/
464/*
465 * instantiate a key and link it into the target keyring atomically
466 */
467int key_instantiate_and_link(struct key *key,
468 const void *data,
469 size_t datalen,
David Howells3e301482005-06-23 22:00:56 -0700470 struct key *keyring,
471 struct key *instkey)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472{
473 int ret;
474
475 if (keyring)
476 down_write(&keyring->sem);
477
David Howells3e301482005-06-23 22:00:56 -0700478 ret = __key_instantiate_and_link(key, data, datalen, keyring, instkey);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700479
480 if (keyring)
481 up_write(&keyring->sem);
482
483 return ret;
David Howells3e301482005-06-23 22:00:56 -0700484
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485} /* end key_instantiate_and_link() */
486
487EXPORT_SYMBOL(key_instantiate_and_link);
488
489/*****************************************************************************/
490/*
491 * negatively instantiate a key and link it into the target keyring atomically
492 */
493int key_negate_and_link(struct key *key,
494 unsigned timeout,
David Howells3e301482005-06-23 22:00:56 -0700495 struct key *keyring,
496 struct key *instkey)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497{
498 struct timespec now;
499 int ret, awaken;
500
501 key_check(key);
502 key_check(keyring);
503
504 awaken = 0;
505 ret = -EBUSY;
506
507 if (keyring)
508 down_write(&keyring->sem);
509
510 down_write(&key_construction_sem);
511
512 /* can't instantiate twice */
David Howells76d8aea2005-06-23 22:00:49 -0700513 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514 /* mark the key as being negatively instantiated */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 atomic_inc(&key->user->nikeys);
David Howells76d8aea2005-06-23 22:00:49 -0700516 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
517 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 now = current_kernel_time();
519 key->expiry = now.tv_sec + timeout;
520
David Howells76d8aea2005-06-23 22:00:49 -0700521 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 awaken = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 ret = 0;
525
526 /* and link it into the destination keyring */
527 if (keyring)
528 ret = __key_link(keyring, key);
David Howells3e301482005-06-23 22:00:56 -0700529
530 /* disable the authorisation key */
531 if (instkey)
532 key_revoke(instkey);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 }
534
535 up_write(&key_construction_sem);
536
537 if (keyring)
538 up_write(&keyring->sem);
539
540 /* wake up anyone waiting for a key to be constructed */
541 if (awaken)
542 wake_up_all(&request_key_conswq);
543
544 return ret;
545
546} /* end key_negate_and_link() */
547
548EXPORT_SYMBOL(key_negate_and_link);
549
550/*****************************************************************************/
551/*
552 * do cleaning up in process context so that we don't have to disable
553 * interrupts all over the place
554 */
555static void key_cleanup(void *data)
556{
557 struct rb_node *_n;
558 struct key *key;
559
560 go_again:
561 /* look for a dead key in the tree */
562 spin_lock(&key_serial_lock);
563
564 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
565 key = rb_entry(_n, struct key, serial_node);
566
567 if (atomic_read(&key->usage) == 0)
568 goto found_dead_key;
569 }
570
571 spin_unlock(&key_serial_lock);
572 return;
573
574 found_dead_key:
575 /* we found a dead key - once we've removed it from the tree, we can
576 * drop the lock */
577 rb_erase(&key->serial_node, &key_serial_tree);
578 spin_unlock(&key_serial_lock);
579
David Howells76d8aea2005-06-23 22:00:49 -0700580 key_check(key);
581
David Howells29db9192005-10-30 15:02:44 -0800582 security_key_free(key);
583
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 /* deal with the user's key tracking and quota */
David Howells76d8aea2005-06-23 22:00:49 -0700585 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 spin_lock(&key->user->lock);
587 key->user->qnkeys--;
588 key->user->qnbytes -= key->quotalen;
589 spin_unlock(&key->user->lock);
590 }
591
592 atomic_dec(&key->user->nkeys);
David Howells76d8aea2005-06-23 22:00:49 -0700593 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 atomic_dec(&key->user->nikeys);
595
596 key_user_put(key->user);
597
598 /* now throw away the key memory */
599 if (key->type->destroy)
600 key->type->destroy(key);
601
602 kfree(key->description);
603
604#ifdef KEY_DEBUGGING
605 key->magic = KEY_DEBUG_MAGIC_X;
606#endif
607 kmem_cache_free(key_jar, key);
608
609 /* there may, of course, be more than one key to destroy */
610 goto go_again;
611
612} /* end key_cleanup() */
613
614/*****************************************************************************/
615/*
616 * dispose of a reference to a key
617 * - when all the references are gone, we schedule the cleanup task to come and
618 * pull it out of the tree in definite process context
619 */
620void key_put(struct key *key)
621{
622 if (key) {
623 key_check(key);
624
625 if (atomic_dec_and_test(&key->usage))
626 schedule_work(&key_cleanup_task);
627 }
628
629} /* end key_put() */
630
631EXPORT_SYMBOL(key_put);
632
633/*****************************************************************************/
634/*
635 * find a key by its serial number
636 */
637struct key *key_lookup(key_serial_t id)
638{
639 struct rb_node *n;
640 struct key *key;
641
642 spin_lock(&key_serial_lock);
643
644 /* search the tree for the specified key */
645 n = key_serial_tree.rb_node;
646 while (n) {
647 key = rb_entry(n, struct key, serial_node);
648
649 if (id < key->serial)
650 n = n->rb_left;
651 else if (id > key->serial)
652 n = n->rb_right;
653 else
654 goto found;
655 }
656
657 not_found:
658 key = ERR_PTR(-ENOKEY);
659 goto error;
660
661 found:
David Howells76d8aea2005-06-23 22:00:49 -0700662 /* pretend it doesn't exist if it's dead */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663 if (atomic_read(&key->usage) == 0 ||
David Howells76d8aea2005-06-23 22:00:49 -0700664 test_bit(KEY_FLAG_DEAD, &key->flags) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -0700665 key->type == &key_type_dead)
666 goto not_found;
667
668 /* this races with key_put(), but that doesn't matter since key_put()
669 * doesn't actually change the key
670 */
671 atomic_inc(&key->usage);
672
673 error:
674 spin_unlock(&key_serial_lock);
675 return key;
676
677} /* end key_lookup() */
678
679/*****************************************************************************/
680/*
681 * find and lock the specified key type against removal
682 * - we return with the sem readlocked
683 */
684struct key_type *key_type_lookup(const char *type)
685{
686 struct key_type *ktype;
687
688 down_read(&key_types_sem);
689
690 /* look up the key type to see if it's one of the registered kernel
691 * types */
692 list_for_each_entry(ktype, &key_types_list, link) {
693 if (strcmp(ktype->name, type) == 0)
694 goto found_kernel_type;
695 }
696
697 up_read(&key_types_sem);
698 ktype = ERR_PTR(-ENOKEY);
699
700 found_kernel_type:
701 return ktype;
702
703} /* end key_type_lookup() */
704
705/*****************************************************************************/
706/*
707 * unlock a key type
708 */
709void key_type_put(struct key_type *ktype)
710{
711 up_read(&key_types_sem);
712
713} /* end key_type_put() */
714
715/*****************************************************************************/
716/*
717 * attempt to update an existing key
718 * - the key has an incremented refcount
719 * - we need to put the key if we get an error
720 */
David Howells664cceb2005-09-28 17:03:15 +0100721static inline key_ref_t __key_update(key_ref_t key_ref,
722 const void *payload, size_t plen)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723{
David Howells664cceb2005-09-28 17:03:15 +0100724 struct key *key = key_ref_to_ptr(key_ref);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 int ret;
726
727 /* need write permission on the key to update it */
David Howells29db9192005-10-30 15:02:44 -0800728 ret = key_permission(key_ref, KEY_WRITE);
729 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 goto error;
731
732 ret = -EEXIST;
733 if (!key->type->update)
734 goto error;
735
736 down_write(&key->sem);
737
738 ret = key->type->update(key, payload, plen);
David Howells76d8aea2005-06-23 22:00:49 -0700739 if (ret == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 /* updating a negative key instantiates it */
David Howells76d8aea2005-06-23 22:00:49 -0700741 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742
743 up_write(&key->sem);
744
745 if (ret < 0)
746 goto error;
David Howells664cceb2005-09-28 17:03:15 +0100747out:
748 return key_ref;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749
David Howells664cceb2005-09-28 17:03:15 +0100750error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751 key_put(key);
David Howells664cceb2005-09-28 17:03:15 +0100752 key_ref = ERR_PTR(ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 goto out;
754
755} /* end __key_update() */
756
757/*****************************************************************************/
758/*
759 * search the specified keyring for a key of the same description; if one is
760 * found, update it, otherwise add a new one
761 */
David Howells664cceb2005-09-28 17:03:15 +0100762key_ref_t key_create_or_update(key_ref_t keyring_ref,
763 const char *type,
764 const char *description,
765 const void *payload,
766 size_t plen,
David Howells7e047ef2006-06-26 00:24:50 -0700767 unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768{
769 struct key_type *ktype;
David Howells664cceb2005-09-28 17:03:15 +0100770 struct key *keyring, *key = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771 key_perm_t perm;
David Howells664cceb2005-09-28 17:03:15 +0100772 key_ref_t key_ref;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 int ret;
774
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 /* look up the key type to see if it's one of the registered kernel
776 * types */
777 ktype = key_type_lookup(type);
778 if (IS_ERR(ktype)) {
David Howells664cceb2005-09-28 17:03:15 +0100779 key_ref = ERR_PTR(-ENODEV);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 goto error;
781 }
782
David Howells664cceb2005-09-28 17:03:15 +0100783 key_ref = ERR_PTR(-EINVAL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 if (!ktype->match || !ktype->instantiate)
785 goto error_2;
786
David Howells664cceb2005-09-28 17:03:15 +0100787 keyring = key_ref_to_ptr(keyring_ref);
788
789 key_check(keyring);
790
David Howellsc3a9d652006-04-10 15:15:21 +0100791 key_ref = ERR_PTR(-ENOTDIR);
792 if (keyring->type != &key_type_keyring)
793 goto error_2;
794
David Howells664cceb2005-09-28 17:03:15 +0100795 down_write(&keyring->sem);
796
797 /* if we're going to allocate a new key, we're going to have
798 * to modify the keyring */
David Howells29db9192005-10-30 15:02:44 -0800799 ret = key_permission(keyring_ref, KEY_WRITE);
800 if (ret < 0) {
801 key_ref = ERR_PTR(ret);
David Howells664cceb2005-09-28 17:03:15 +0100802 goto error_3;
David Howells29db9192005-10-30 15:02:44 -0800803 }
David Howells664cceb2005-09-28 17:03:15 +0100804
David Howells1d9b7d92006-03-25 03:06:52 -0800805 /* if it's possible to update this type of key, search for an existing
806 * key of the same type and description in the destination keyring and
807 * update that instead if possible
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 */
David Howells1d9b7d92006-03-25 03:06:52 -0800809 if (ktype->update) {
810 key_ref = __keyring_search_one(keyring_ref, ktype, description,
811 0);
812 if (!IS_ERR(key_ref))
813 goto found_matching_key;
814 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 /* decide on the permissions we want */
David Howells29db9192005-10-30 15:02:44 -0800817 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
818 perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819
820 if (ktype->read)
David Howells664cceb2005-09-28 17:03:15 +0100821 perm |= KEY_POS_READ | KEY_USR_READ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822
823 if (ktype == &key_type_keyring || ktype->update)
824 perm |= KEY_USR_WRITE;
825
826 /* allocate a new key */
827 key = key_alloc(ktype, description, current->fsuid, current->fsgid,
David Howells7e047ef2006-06-26 00:24:50 -0700828 current, perm, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829 if (IS_ERR(key)) {
David Howells664cceb2005-09-28 17:03:15 +0100830 key_ref = ERR_PTR(PTR_ERR(key));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 goto error_3;
832 }
833
834 /* instantiate it and link it into the target keyring */
David Howells3e301482005-06-23 22:00:56 -0700835 ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700836 if (ret < 0) {
837 key_put(key);
David Howells664cceb2005-09-28 17:03:15 +0100838 key_ref = ERR_PTR(ret);
839 goto error_3;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840 }
841
David Howells664cceb2005-09-28 17:03:15 +0100842 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
843
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844 error_3:
845 up_write(&keyring->sem);
846 error_2:
847 key_type_put(ktype);
848 error:
David Howells664cceb2005-09-28 17:03:15 +0100849 return key_ref;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850
851 found_matching_key:
852 /* we found a matching key, so we're going to try to update it
853 * - we can drop the locks first as we have the key pinned
854 */
855 up_write(&keyring->sem);
856 key_type_put(ktype);
857
David Howells664cceb2005-09-28 17:03:15 +0100858 key_ref = __key_update(key_ref, payload, plen);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859 goto error;
860
861} /* end key_create_or_update() */
862
863EXPORT_SYMBOL(key_create_or_update);
864
865/*****************************************************************************/
866/*
867 * update a key
868 */
David Howells664cceb2005-09-28 17:03:15 +0100869int key_update(key_ref_t key_ref, const void *payload, size_t plen)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870{
David Howells664cceb2005-09-28 17:03:15 +0100871 struct key *key = key_ref_to_ptr(key_ref);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 int ret;
873
874 key_check(key);
875
876 /* the key must be writable */
David Howells29db9192005-10-30 15:02:44 -0800877 ret = key_permission(key_ref, KEY_WRITE);
878 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700879 goto error;
880
881 /* attempt to update it if supported */
882 ret = -EOPNOTSUPP;
883 if (key->type->update) {
884 down_write(&key->sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885
David Howells29db9192005-10-30 15:02:44 -0800886 ret = key->type->update(key, payload, plen);
David Howells76d8aea2005-06-23 22:00:49 -0700887 if (ret == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888 /* updating a negative key instantiates it */
David Howells76d8aea2005-06-23 22:00:49 -0700889 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890
891 up_write(&key->sem);
892 }
893
894 error:
895 return ret;
896
897} /* end key_update() */
898
899EXPORT_SYMBOL(key_update);
900
901/*****************************************************************************/
902/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 * revoke a key
904 */
905void key_revoke(struct key *key)
906{
907 key_check(key);
908
909 /* make sure no one's trying to change or use the key when we mark
910 * it */
911 down_write(&key->sem);
David Howells76d8aea2005-06-23 22:00:49 -0700912 set_bit(KEY_FLAG_REVOKED, &key->flags);
David Howells04c567d2006-06-22 14:47:18 -0700913
914 if (key->type->revoke)
915 key->type->revoke(key);
916
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 up_write(&key->sem);
918
919} /* end key_revoke() */
920
921EXPORT_SYMBOL(key_revoke);
922
923/*****************************************************************************/
924/*
925 * register a type of key
926 */
927int register_key_type(struct key_type *ktype)
928{
929 struct key_type *p;
930 int ret;
931
932 ret = -EEXIST;
933 down_write(&key_types_sem);
934
935 /* disallow key types with the same name */
936 list_for_each_entry(p, &key_types_list, link) {
937 if (strcmp(p->name, ktype->name) == 0)
938 goto out;
939 }
940
941 /* store the type */
942 list_add(&ktype->link, &key_types_list);
943 ret = 0;
944
945 out:
946 up_write(&key_types_sem);
947 return ret;
948
949} /* end register_key_type() */
950
951EXPORT_SYMBOL(register_key_type);
952
953/*****************************************************************************/
954/*
955 * unregister a type of key
956 */
957void unregister_key_type(struct key_type *ktype)
958{
959 struct rb_node *_n;
960 struct key *key;
961
962 down_write(&key_types_sem);
963
964 /* withdraw the key type */
965 list_del_init(&ktype->link);
966
David Howells76d8aea2005-06-23 22:00:49 -0700967 /* mark all the keys of this type dead */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 spin_lock(&key_serial_lock);
969
970 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
971 key = rb_entry(_n, struct key, serial_node);
972
David Howells76d8aea2005-06-23 22:00:49 -0700973 if (key->type == ktype)
974 key->type = &key_type_dead;
975 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700976
David Howells76d8aea2005-06-23 22:00:49 -0700977 spin_unlock(&key_serial_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978
David Howells76d8aea2005-06-23 22:00:49 -0700979 /* make sure everyone revalidates their keys */
Paul E. McKenneyb2b18662005-06-25 14:55:38 -0700980 synchronize_rcu();
David Howells76d8aea2005-06-23 22:00:49 -0700981
982 /* we should now be able to destroy the payloads of all the keys of
983 * this type with impunity */
984 spin_lock(&key_serial_lock);
985
986 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
987 key = rb_entry(_n, struct key, serial_node);
988
989 if (key->type == ktype) {
990 if (ktype->destroy)
991 ktype->destroy(key);
Randy Dunlapa7807a32006-06-27 02:53:54 -0700992 memset(&key->payload, KEY_DESTROY, sizeof(key->payload));
David Howells76d8aea2005-06-23 22:00:49 -0700993 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994 }
995
996 spin_unlock(&key_serial_lock);
997 up_write(&key_types_sem);
998
999} /* end unregister_key_type() */
1000
1001EXPORT_SYMBOL(unregister_key_type);
1002
1003/*****************************************************************************/
1004/*
1005 * initialise the key management stuff
1006 */
1007void __init key_init(void)
1008{
1009 /* allocate a slab in which we can store keys */
1010 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1011 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1012
1013 /* add the special key types */
1014 list_add_tail(&key_type_keyring.link, &key_types_list);
1015 list_add_tail(&key_type_dead.link, &key_types_list);
1016 list_add_tail(&key_type_user.link, &key_types_list);
1017
1018 /* record the root user tracking */
1019 rb_link_node(&root_key_user.node,
1020 NULL,
1021 &key_user_tree.rb_node);
1022
1023 rb_insert_color(&root_key_user.node,
1024 &key_user_tree);
1025
1026 /* record root's user standard keyrings */
1027 key_check(&root_user_keyring);
1028 key_check(&root_session_keyring);
1029
1030 __key_insert_serial(&root_user_keyring);
1031 __key_insert_serial(&root_session_keyring);
1032
1033 keyring_publish_name(&root_user_keyring);
1034 keyring_publish_name(&root_session_keyring);
1035
1036 /* link the two root keyrings together */
1037 key_link(&root_session_keyring, &root_user_keyring);
David Howells76d8aea2005-06-23 22:00:49 -07001038
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039} /* end key_init() */