summaryrefslogtreecommitdiffstats
path: root/net/mac80211/key.c
blob: 19b480de4bbcbfa498f1d520ca9db8f798d26cce (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
 * Copyright 2007-2008	Johannes Berg <johannes@sipsolutions.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/if_ether.h>
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/rtnetlink.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "debugfs_key.h"
#include "aes_ccm.h"
#include "aes_cmac.h"


/**
 * DOC: Key handling basics
 *
 * Key handling in mac80211 is done based on per-interface (sub_if_data)
 * keys and per-station keys. Since each station belongs to an interface,
 * each station key also belongs to that interface.
 *
 * Hardware acceleration is done on a best-effort basis, for each key
 * that is eligible the hardware is asked to enable that key but if
 * it cannot do that they key is simply kept for software encryption.
 * There is currently no way of knowing this except by looking into
 * debugfs.
 *
 * All key operations are protected internally so you can call them at
 * any time.
 *
 * Within mac80211, key references are, just as STA structure references,
 * protected by RCU. Note, however, that some things are unprotected,
 * namely the key->sta dereferences within the hardware acceleration
 * functions. This means that sta_info_destroy() must flush the key todo
 * list.
 *
 * All the direct key list manipulation functions must not sleep because
 * they can operate on STA info structs that are protected by RCU.
 */

static const u8 bcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };

/* key mutex: used to synchronise todo runners */
static DEFINE_MUTEX(key_mutex);
static DEFINE_SPINLOCK(todo_lock);
static LIST_HEAD(todo_list);

static void key_todo(struct work_struct *work)
{
	ieee80211_key_todo();
}

static DECLARE_WORK(todo_work, key_todo);

/**
 * add_todo - add todo item for a key
 *
 * @key: key to add to do item for
 * @flag: todo flag(s)
 */
static void add_todo(struct ieee80211_key *key, u32 flag)
{
	if (!key)
		return;

	spin_lock(&todo_lock);
	key->flags |= flag;
	/*
	 * Remove again if already on the list so that we move it to the end.
	 */
	if (!list_empty(&key->todo))
		list_del(&key->todo);
	list_add_tail(&key->todo, &todo_list);
	schedule_work(&todo_work);
	spin_unlock(&todo_lock);
}

/**
 * ieee80211_key_lock - lock the mac80211 key operation lock
 *
 * This locks the (global) mac80211 key operation lock, all
 * key operations must be done under this lock.
 */
static void ieee80211_key_lock(void)
{
	mutex_lock(&key_mutex);
}

/**
 * ieee80211_key_unlock - unlock the mac80211 key operation lock
 */
static void ieee80211_key_unlock(void)
{
	mutex_unlock(&key_mutex);
}

static void assert_key_lock(void)
{
	WARN_ON(!mutex_is_locked(&key_mutex));
}

static struct ieee80211_sta *get_sta_for_key(struct ieee80211_key *key)
{
	if (key->sta)
		return &key->sta->sta;

	return NULL;
}

static void ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
{
	struct ieee80211_sub_if_data *sdata;
	struct ieee80211_sta *sta;
	int ret;

	assert_key_lock();
	might_sleep();

	if (!key->local->ops->set_key)
		return;

	sta = get_sta_for_key(key);

	sdata = key->sdata;
	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
		sdata = container_of(sdata->bss,
				     struct ieee80211_sub_if_data,
				     u.ap);

	ret = key->local->ops->set_key(local_to_hw(key->local), SET_KEY,
				       &sdata->vif, sta, &key->conf);

	if (!ret) {
		spin_lock(&todo_lock);
		key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
		spin_unlock(&todo_lock);
	}

	if (ret && ret != -ENOSPC && ret != -EOPNOTSUPP)
		printk(KERN_ERR "mac80211-%s: failed to set key "
		       "(%d, %pM) to hardware (%d)\n",
		       wiphy_name(key->local->hw.wiphy),
		       key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);
}

static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
{
	struct ieee80211_sub_if_data *sdata;
	struct ieee80211_sta *sta;
	int ret;

	assert_key_lock();
	might_sleep();

	if (!key || !key->local->ops->set_key)
		return;

	spin_lock(&todo_lock);
	if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
		spin_unlock(&todo_lock);
		return;
	}
	spin_unlock(&todo_lock);

	sta = get_sta_for_key(key);
	sdata = key->sdata;

	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
		sdata = container_of(sdata->bss,
				     struct ieee80211_sub_if_data,
				     u.ap);

	ret = key->local->ops->set_key(local_to_hw(key->local), DISABLE_KEY,
				       &sdata->vif, sta, &key->conf);

	if (ret)
		printk(KERN_ERR "mac80211-%s: failed to remove key "
		       "(%d, %pM) from hardware (%d)\n",
		       wiphy_name(key->local->hw.wiphy),
		       key->conf.keyidx, sta ? sta->addr : bcast_addr, ret);

	spin_lock(&todo_lock);
	key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
	spin_unlock(&todo_lock);
}

static void __ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata,
					int idx)
{
	struct ieee80211_key *key = NULL;

	if (idx >= 0 && idx < NUM_DEFAULT_KEYS)
		key = sdata->keys[idx];

	rcu_assign_pointer(sdata->default_key, key);

	if (key)
		add_todo(key, KEY_FLAG_TODO_DEFKEY);
}

void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx)
{
	unsigned long flags;

	spin_lock_irqsave(&sdata->local->key_lock, flags);
	__ieee80211_set_default_key(sdata, idx);
	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
}

static void
__ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata, int idx)
{
	struct ieee80211_key *key = NULL;

	if (idx >= NUM_DEFAULT_KEYS &&
	    idx < NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS)
		key = sdata->keys[idx];

	rcu_assign_pointer(sdata->default_mgmt_key, key);

	if (key)
		add_todo(key, KEY_FLAG_TODO_DEFMGMTKEY);
}

void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
				    int idx)
{
	unsigned long flags;

	spin_lock_irqsave(&sdata->local->key_lock, flags);
	__ieee80211_set_default_mgmt_key(sdata, idx);
	spin_unlock_irqrestore(&sdata->local->key_lock, flags);
}


static void __ieee80211_key_replace(struct ieee80211_sub_if_data *sdata,
				    struct sta_info *sta,
				    struct ieee80211_key *old,
				    struct ieee80211_key *new)
{
	int idx, defkey, defmgmtkey;

	if (new)
		list_add(&new->list, &sdata->key_list);

	if (sta) {
		rcu_assign_pointer(sta->key, new);
	} else {
		WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);

		if (old)
			idx = old->conf.keyidx;
		else
			idx = new->conf.keyidx;

		defkey = old && sdata->default_key == old;
		defmgmtkey = old && sdata->default_mgmt_key == old;

		if (defkey && !new)
			__ieee80211_set_default_key(sdata, -1);
		if (defmgmtkey && !new)
			__ieee80211_set_default_mgmt_key(sdata, -1);

		rcu_assign_pointer(sdata->keys[idx], new);
		if (defkey && new)
			__ieee80211_set_default_key(sdata, new->conf.keyidx);
		if (defmgmtkey && new)
			__ieee80211_set_default_mgmt_key(sdata,
							 new->conf.keyidx);
	}

	if (old) {
		/*
		 * We'll use an empty list to indicate that the key
		 * has already been removed.
		 */
		list_del_init(&old->list);
	}
}

struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
					  int idx,
					  size_t key_len,
					  const u8 *key_data)
{
	struct ieee80211_key *key;

	BUG_ON(idx < 0 || idx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS);

	key = kzalloc(sizeof(struct ieee80211_key) + key_len, GFP_KERNEL);
	if (!key)
		return NULL;

	/*
	 * Default to software encryption; we'll later upload the
	 * key to the hardware if possible.
	 */
	key->conf.flags = 0;
	key->flags = 0;

	key->conf.alg = alg;
	key->conf.keyidx = idx;
	key->conf.keylen = key_len;
	switch (alg) {
	case ALG_WEP:
		key->conf.iv_len = WEP_IV_LEN;
		key->conf.icv_len = WEP_ICV_LEN;
		break;
	case ALG_TKIP:
		key->conf.iv_len = TKIP_IV_LEN;
		key->conf.icv_len = TKIP_ICV_LEN;
		break;
	case ALG_CCMP:
		key->conf.iv_len = CCMP_HDR_LEN;
		key->conf.icv_len = CCMP_MIC_LEN;
		break;
	case ALG_AES_CMAC:
		key->conf.iv_len = 0;
		key->conf.icv_len = sizeof(struct ieee80211_mmie);
		break;
	}
	memcpy(key->conf.key, key_data, key_len);
	INIT_LIST_HEAD(&key->list);
	INIT_LIST_HEAD(&key->todo);

	if (alg == ALG_CCMP) {
		/*
		 * Initialize AES key state here as an optimization so that
		 * it does not need to be initialized for every packet.
		 */
		key->u.ccmp.tfm = ieee80211_aes_key_setup_encrypt(key_data);
		if (!key->u.ccmp.tfm) {
			kfree(key);
			return NULL;
		}
	}

	if (alg == ALG_AES_CMAC) {
		/*
		 * Initialize AES key state here as an optimization so that
		 * it does not need to be initialized for every packet.
		 */
		key->u.aes_cmac.tfm =
			ieee80211_aes_cmac_key_setup(key_data);
		if (!key->u.aes_cmac.tfm) {
			kfree(key);
			return NULL;
		}
	}

	return key;
}

void ieee80211_key_link(struct ieee80211_key *key,
			struct ieee80211_sub_if_data *sdata,
			struct sta_info *sta)
{
	struct ieee80211_key *old_key;
	unsigned long flags;
	int idx;

	BUG_ON(!sdata);
	BUG_ON(!key);

	idx = key->conf.keyidx;
	key->local = sdata->local;
	key->sdata = sdata;
	key->sta = sta;

	if (sta) {
		/*
		 * some hardware cannot handle TKIP with QoS, so
		 * we indicate whether QoS could be in use.
		 */
		if (test_sta_flags(sta, WLAN_STA_WME))
			key->conf.flags |= IEEE80211_KEY_FLAG_WMM_STA;

		/*
		 * This key is for a specific sta interface,
		 * inform the driver that it should try to store
		 * this key as pairwise key.
		 */
		key->conf.flags |= IEEE80211_KEY_FLAG_PAIRWISE;
	} else {
		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
			struct sta_info *ap;

			/*
			 * We're getting a sta pointer in,
			 * so must be under RCU read lock.
			 */

			/* same here, the AP could be using QoS */
			ap = sta_info_get(key->local, key->sdata->u.sta.bssid);
			if (ap) {
				if (test_sta_flags(ap, WLAN_STA_WME))
					key->conf.flags |=
						IEEE80211_KEY_FLAG_WMM_STA;
			}
		}
	}

	spin_lock_irqsave(&sdata->local->key_lock, flags);

	if (sta)
		old_key = sta->key;
	else
		old_key = sdata->keys[idx];

	__ieee80211_key_replace(sdata, sta, old_key, key);

	spin_unlock_irqrestore(&sdata->local->key_lock, flags);

	/* free old key later */
	add_todo(old_key, KEY_FLAG_TODO_DELETE);

	add_todo(key, KEY_FLAG_TODO_ADD_DEBUGFS);
	if (netif_running(sdata->dev))
		add_todo(key, KEY_FLAG_TODO_HWACCEL_ADD);
}

static void __ieee80211_key_free(struct ieee80211_key *key)
{
	/*
	 * Replace key with nothingness if it was ever used.
	 */
	if (key->sdata)
		__ieee80211_key_replace(key->sdata, key->sta,
					key, NULL);

	add_todo(key, KEY_FLAG_TODO_DELETE);
}

void ieee80211_key_free(struct ieee80211_key *key)
{
	unsigned long flags;

	if (!key)
		return;

	if (!key->sdata) {
		/* The key has not been linked yet, simply free it
		 * and don't Oops */
		if (key->conf.alg == ALG_CCMP)
			ieee80211_aes_key_free(key->u.ccmp.tfm);
		kfree(key);
		return;
	}

	spin_lock_irqsave(&key->sdata->local->key_lock, flags);
	__ieee80211_key_free(key);
	spin_unlock_irqrestore(&key->sdata->local->key_lock, flags);
}

/*
 * To be safe against concurrent manipulations of the list (which shouldn't
 * actually happen) we need to hold the spinlock. But under the spinlock we
 * can't actually do much, so we defer processing to the todo list. Then run
 * the todo list to be sure the operation and possibly previously pending
 * operations are completed.
 */
static void ieee80211_todo_for_each_key(struct ieee80211_sub_if_data *sdata,
					u32 todo_flags)
{
	struct ieee80211_key *key;
	unsigned long flags;

	might_sleep();

	spin_lock_irqsave(&sdata->local->key_lock, flags);
	list_for_each_entry(key, &sdata->key_list, list)
		add_todo(key, todo_flags);
	spin_unlock_irqrestore(&sdata->local->key_lock, flags);

	ieee80211_key_todo();
}

void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
{
	ASSERT_RTNL();

	if (WARN_ON(!netif_running(sdata->dev)))
		return;

	ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_ADD);
}

void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
{
	ASSERT_RTNL();

	ieee80211_todo_for_each_key(sdata, KEY_FLAG_TODO_HWACCEL_REMOVE);
}

static void __ieee80211_key_destroy(struct ieee80211_key *key)
{
	if (!key)
		return;

	ieee80211_key_disable_hw_accel(key);

	if (key->conf.alg == ALG_CCMP)
		ieee80211_aes_key_free(key->u.ccmp.tfm);
	if (key->conf.alg == ALG_AES_CMAC)
		ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
	ieee80211_debugfs_key_remove(key);

	kfree(key);
}

static void __ieee80211_key_todo(void)
{
	struct ieee80211_key *key;
	bool work_done;
	u32 todoflags;

	/*
	 * NB: sta_info_destroy relies on this!
	 */
	synchronize_rcu();

	spin_lock(&todo_lock);
	while (!list_empty(&todo_list)) {
		key = list_first_entry(&todo_list, struct ieee80211_key, todo);
		list_del_init(&key->todo);
		todoflags = key->flags & (KEY_FLAG_TODO_ADD_DEBUGFS |
					  KEY_FLAG_TODO_DEFKEY |
					  KEY_FLAG_TODO_DEFMGMTKEY |
					  KEY_FLAG_TODO_HWACCEL_ADD |
					  KEY_FLAG_TODO_HWACCEL_REMOVE |
					  KEY_FLAG_TODO_DELETE);
		key->flags &= ~todoflags;
		spin_unlock(&todo_lock);

		work_done = false;

		if (todoflags & KEY_FLAG_TODO_ADD_DEBUGFS) {
			ieee80211_debugfs_key_add(key);
			work_done = true;
		}
		if (todoflags & KEY_FLAG_TODO_DEFKEY) {
			ieee80211_debugfs_key_remove_default(key->sdata);
			ieee80211_debugfs_key_add_default(key->sdata);
			work_done = true;
		}
		if (todoflags & KEY_FLAG_TODO_DEFMGMTKEY) {
			ieee80211_debugfs_key_remove_mgmt_default(key->sdata);
			ieee80211_debugfs_key_add_mgmt_default(key->sdata);
			work_done = true;
		}
		if (todoflags & KEY_FLAG_TODO_HWACCEL_ADD) {
			ieee80211_key_enable_hw_accel(key);
			work_done = true;
		}
		if (todoflags & KEY_FLAG_TODO_HWACCEL_REMOVE) {
			ieee80211_key_disable_hw_accel(key);
			work_done = true;
		}
		if (todoflags & KEY_FLAG_TODO_DELETE) {
			__ieee80211_key_destroy(key);
			work_done = true;
		}

		WARN_ON(!work_done);

		spin_lock(&todo_lock);
	}
	spin_unlock(&todo_lock);
}

void ieee80211_key_todo(void)
{
	ieee80211_key_lock();
	__ieee80211_key_todo();
	ieee80211_key_unlock();
}

void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_key *key, *tmp;
	unsigned long flags;

	ieee80211_key_lock();

	ieee80211_debugfs_key_remove_default(sdata);
	ieee80211_debugfs_key_remove_mgmt_default(sdata);

	spin_lock_irqsave(&sdata->local->key_lock, flags);
	list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
		__ieee80211_key_free(key);
	spin_unlock_irqrestore(&sdata->local->key_lock, flags);

	__ieee80211_key_todo();

	ieee80211_key_unlock();
}
OpenPOWER on IntegriCloud