aboutsummaryrefslogtreecommitdiffstats
path: root/net/mac80211/key.c
blob: af3c56482c80b519d97d166373c05860b47f28dd (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
/*
 * 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 <linux/slab.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "driver-ops.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 algorithms
 * that are implemented in software,  for each key the hardware is asked
 * to enable that key for offloading but if it cannot do that the key is
 * simply kept for software encryption (unless it is for an algorithm
 * that isn't implemented in software).
 * There is currently no way of knowing whether a key is handled in SW
 * or HW except by looking into debugfs.
 *
 * All key management is internally protected by a mutex. Within all
 * other parts of 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
 * remove the key which waits for an RCU grace period.
 */

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

static void assert_key_lock(struct ieee80211_local *local)
{
	lockdep_assert_held(&local->key_mtx);
}

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

	return NULL;
}

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

	might_sleep();

	if (!key->local->ops->set_key)
		goto out_unsupported;

	assert_key_lock(key->local);

	sta = get_sta_for_key(key);

	/*
	 * If this is a per-STA GTK, check if it
	 * is supported; if not, return.
	 */
	if (sta && !(key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE) &&
	    !(key->local->hw.flags & IEEE80211_HW_SUPPORTS_PER_STA_GTK))
		goto out_unsupported;

	sdata = key->sdata;
	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
		/*
		 * The driver doesn't know anything about VLAN interfaces.
		 * Hence, don't send GTKs for VLAN interfaces to the driver.
		 */
		if (!(key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE))
			goto out_unsupported;
		sdata = container_of(sdata->bss,
				     struct ieee80211_sub_if_data,
				     u.ap);
	}

	ret = drv_set_key(key->local, SET_KEY, sdata, sta, &key->conf);

	if (!ret) {
		key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
		return 0;
	}

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

 out_unsupported:
	switch (key->conf.cipher) {
	case WLAN_CIPHER_SUITE_WEP40:
	case WLAN_CIPHER_SUITE_WEP104:
	case WLAN_CIPHER_SUITE_TKIP:
	case WLAN_CIPHER_SUITE_CCMP:
	case WLAN_CIPHER_SUITE_AES_CMAC:
		/* all of these we can do in software */
		return 0;
	default:
		return -EINVAL;
	}
}

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

	might_sleep();

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

	assert_key_lock(key->local);

	if (!(key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
		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 = drv_set_key(key->local, DISABLE_KEY, sdata,
			  sta, &key->conf);

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

	key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
}

void ieee80211_key_removed(struct ieee80211_key_conf *key_conf)
{
	struct ieee80211_key *key;

	key = container_of(key_conf, struct ieee80211_key, conf);

	might_sleep();
	assert_key_lock(key->local);

	key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;

	/*
	 * Flush TX path to avoid attempts to use this key
	 * after this function returns. Until then, drivers
	 * must be prepared to handle the key.
	 */
	synchronize_rcu();
}
EXPORT_SYMBOL_GPL(ieee80211_key_removed);

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

	assert_key_lock(sdata->local);

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

	if (uni)
		rcu_assign_pointer(sdata->default_unicast_key, key);
	if (multi)
		rcu_assign_pointer(sdata->default_multicast_key, key);

	ieee80211_debugfs_key_update_default(sdata);
}

void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx,
			       bool uni, bool multi)
{
	mutex_lock(&sdata->local->key_mtx);
	__ieee80211_set_default_key(sdata, idx, uni, multi);
	mutex_unlock(&sdata->local->key_mtx);
}

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

	assert_key_lock(sdata->local);

	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);

	ieee80211_debugfs_key_update_default(sdata);
}

void ieee80211_set_default_mgmt_key(struct ieee80211_sub_if_data *sdata,
				    int idx)
{
	mutex_lock(&sdata->local->key_mtx);
	__ieee80211_set_default_mgmt_key(sdata, idx);
	mutex_unlock(&sdata->local->key_mtx);
}


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

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

	if (sta && pairwise) {
		rcu_assign_pointer(sta->ptk, new);
	} else if (sta) {
		if (old)
			idx = old->conf.keyidx;
		else
			idx = new->conf.keyidx;
		rcu_assign_pointer(sta->gtk[idx], new);
	} else {
		WARN_ON(new && old && new->conf.keyidx != old->conf.keyidx);

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

		defunikey = old && sdata->default_unicast_key == old;
		defmultikey = old && sdata->default_multicast_key == old;
		defmgmtkey = old && sdata->default_mgmt_key == old;

		if (defunikey && !new)
			__ieee80211_set_default_key(sdata, -1, true, false);
		if (defmultikey && !new)
			__ieee80211_set_default_key(sdata, -1, false, true);
		if (defmgmtkey && !new)
			__ieee80211_set_default_mgmt_key(sdata, -1);

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

	if (old)
		list_del(&old->list);
}

struct ieee80211_key *ieee80211_key_alloc(u32 cipher, int idx, size_t key_len,
					  const u8 *key_data,
					  size_t seq_len, const u8 *seq)
{
	struct ieee80211_key *key;
	int i, j, err;

	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 ERR_PTR(-ENOMEM);

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

	key->conf.cipher = cipher;
	key->conf.keyidx = idx;
	key->conf.keylen = key_len;
	switch (cipher) {
	case WLAN_CIPHER_SUITE_WEP40:
	case WLAN_CIPHER_SUITE_WEP104:
		key->conf.iv_len = WEP_IV_LEN;
		key->conf.icv_len = WEP_ICV_LEN;
		break;
	case WLAN_CIPHER_SUITE_TKIP:
		key->conf.iv_len = TKIP_IV_LEN;
		key->conf.icv_len = TKIP_ICV_LEN;
		if (seq) {
			for (i = 0; i < NUM_RX_DATA_QUEUES; i++) {
				key->u.tkip.rx[i].iv32 =
					get_unaligned_le32(&seq[2]);
				key->u.tkip.rx[i].iv16 =
					get_unaligned_le16(seq);
			}
		}
		break;
	case WLAN_CIPHER_SUITE_CCMP:
		key->conf.iv_len = CCMP_HDR_LEN;
		key->conf.icv_len = CCMP_MIC_LEN;
		if (seq) {
			for (i = 0; i < NUM_RX_DATA_QUEUES + 1; i++)
				for (j = 0; j < CCMP_PN_LEN; j++)
					key->u.ccmp.rx_pn[i][j] =
						seq[CCMP_PN_LEN - j - 1];
		}
		/*
		 * 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 (IS_ERR(key->u.ccmp.tfm)) {
			err = PTR_ERR(key->u.ccmp.tfm);
			kfree(key);
			return ERR_PTR(err);
		}
		break;
	case WLAN_CIPHER_SUITE_AES_CMAC:
		key->conf.iv_len = 0;
		key->conf.icv_len = sizeof(struct ieee80211_mmie);
		if (seq)
			for (j = 0; j < 6; j++)
				key->u.aes_cmac.rx_pn[j] = seq[6 - j - 1];
		/*
		 * 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 (IS_ERR(key->u.aes_cmac.tfm)) {
			err = PTR_ERR(key->u.aes_cmac.tfm);
			kfree(key);
			return ERR_PTR(err);
		}
		break;
	}
	memcpy(key->conf.key, key_data, key_len);
	INIT_LIST_HEAD(&key->list);

	return key;
}

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

	/*
	 * Synchronize so the TX path can no longer be using
	 * this key before we free/remove it.
	 */
	synchronize_rcu();

	if (key->local)
		ieee80211_key_disable_hw_accel(key);

	if (key->conf.cipher == WLAN_CIPHER_SUITE_CCMP)
		ieee80211_aes_key_free(key->u.ccmp.tfm);
	if (key->conf.cipher == WLAN_CIPHER_SUITE_AES_CMAC)
		ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
	if (key->local)
		ieee80211_debugfs_key_remove(key);

	kfree(key);
}

int ieee80211_key_link(struct ieee80211_key *key,
		       struct ieee80211_sub_if_data *sdata,
		       struct sta_info *sta)
{
	struct ieee80211_key *old_key;
	int idx, ret;
	bool pairwise;

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

	pairwise = key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE;
	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;
	} else {
		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
			struct sta_info *ap;

			/*
			 * We're getting a sta pointer in, so must be under
			 * appropriate locking for sta_info_get().
			 */

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

	mutex_lock(&sdata->local->key_mtx);

	if (sta && pairwise)
		old_key = sta->ptk;
	else if (sta)
		old_key = sta->gtk[idx];
	else
		old_key = sdata->keys[idx];

	__ieee80211_key_replace(sdata, sta, pairwise, old_key, key);
	__ieee80211_key_destroy(old_key);

	ieee80211_debugfs_key_add(key);

	ret = ieee80211_key_enable_hw_accel(key);

	mutex_unlock(&sdata->local->key_mtx);

	return ret;
}

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->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE,
				key, NULL);
	__ieee80211_key_destroy(key);
}

void ieee80211_key_free(struct ieee80211_local *local,
			struct ieee80211_key *key)
{
	if (!key)
		return;

	mutex_lock(&local->key_mtx);
	__ieee80211_key_free(key);
	mutex_unlock(&local->key_mtx);
}

void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_key *key;

	ASSERT_RTNL();

	if (WARN_ON(!ieee80211_sdata_running(sdata)))
		return;

	mutex_lock(&sdata->local->key_mtx);

	list_for_each_entry(key, &sdata->key_list, list)
		ieee80211_key_enable_hw_accel(key);

	mutex_unlock(&sdata->local->key_mtx);
}

void ieee80211_disable_keys(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_key *key;

	ASSERT_RTNL();

	mutex_lock(&sdata->local->key_mtx);

	list_for_each_entry(key, &sdata->key_list, list)
		ieee80211_key_disable_hw_accel(key);

	mutex_unlock(&sdata->local->key_mtx);
}

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

	mutex_lock(&sdata->local->key_mtx);

	ieee80211_debugfs_key_remove_mgmt_default(sdata);

	list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
		__ieee80211_key_free(key);

	ieee80211_debugfs_key_update_default(sdata);

	mutex_unlock(&sdata->local->key_mtx);
}