summaryrefslogtreecommitdiff
path: root/net/mac80211/wpa.c
blob: 4d05ad9403aeed594d87f5d6eeb70b2b8ac4625b (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
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
/*
 * Copyright 2002-2004, Instant802 Networks, Inc.
 * Copyright 2008, Jouni Malinen <j@w1.fi>
 *
 * 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/netdevice.h>
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/compiler.h>
#include <linux/ieee80211.h>
#include <linux/gfp.h>
#include <asm/unaligned.h>
#include <net/mac80211.h>
#include <crypto/aes.h>

#include "ieee80211_i.h"
#include "michael.h"
#include "tkip.h"
#include "aes_ccm.h"
#include "aes_cmac.h"
#include "wpa.h"

ieee80211_tx_result
ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
{
	u8 *data, *key, *mic;
	size_t data_len;
	unsigned int hdrlen;
	struct ieee80211_hdr *hdr;
	struct sk_buff *skb = tx->skb;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	int tail;

	hdr = (struct ieee80211_hdr *)skb->data;
	if (!tx->key || tx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP ||
	    skb->len < 24 || !ieee80211_is_data_present(hdr->frame_control))
		return TX_CONTINUE;

	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	if (skb->len < hdrlen)
		return TX_DROP;

	data = skb->data + hdrlen;
	data_len = skb->len - hdrlen;

	if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE)) {
		/* Need to use software crypto for the test */
		info->control.hw_key = NULL;
	}

	if (info->control.hw_key &&
	    (info->flags & IEEE80211_TX_CTL_DONTFRAG ||
	     tx->local->ops->set_frag_threshold) &&
	    !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
		/* hwaccel - with no need for SW-generated MMIC */
		return TX_CONTINUE;
	}

	tail = MICHAEL_MIC_LEN;
	if (!info->control.hw_key)
		tail += TKIP_ICV_LEN;

	if (WARN_ON(skb_tailroom(skb) < tail ||
		    skb_headroom(skb) < TKIP_IV_LEN))
		return TX_DROP;

	key = &tx->key->conf.key[NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY];
	mic = skb_put(skb, MICHAEL_MIC_LEN);
	michael_mic(key, hdr, data, data_len, mic);
	if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE))
		mic[0]++;

	return TX_CONTINUE;
}


ieee80211_rx_result
ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
{
	u8 *data, *key = NULL;
	size_t data_len;
	unsigned int hdrlen;
	u8 mic[MICHAEL_MIC_LEN];
	struct sk_buff *skb = rx->skb;
	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;

	/*
	 * it makes no sense to check for MIC errors on anything other
	 * than data frames.
	 */
	if (!ieee80211_is_data_present(hdr->frame_control))
		return RX_CONTINUE;

	/*
	 * No way to verify the MIC if the hardware stripped it or
	 * the IV with the key index. In this case we have solely rely
	 * on the driver to set RX_FLAG_MMIC_ERROR in the event of a
	 * MIC failure report.
	 */
	if (status->flag & (RX_FLAG_MMIC_STRIPPED | RX_FLAG_IV_STRIPPED)) {
		if (status->flag & RX_FLAG_MMIC_ERROR)
			goto mic_fail;

		if (!(status->flag & RX_FLAG_IV_STRIPPED) && rx->key)
			goto update_iv;

		return RX_CONTINUE;
	}

	/*
	 * Some hardware seems to generate Michael MIC failure reports; even
	 * though, the frame was not encrypted with TKIP and therefore has no
	 * MIC. Ignore the flag them to avoid triggering countermeasures.
	 */
	if (!rx->key || rx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP ||
	    !(status->flag & RX_FLAG_DECRYPTED))
		return RX_CONTINUE;

	if (rx->sdata->vif.type == NL80211_IFTYPE_AP && rx->key->conf.keyidx) {
		/*
		 * APs with pairwise keys should never receive Michael MIC
		 * errors for non-zero keyidx because these are reserved for
		 * group keys and only the AP is sending real multicast
		 * frames in the BSS. (
		 */
		return RX_DROP_UNUSABLE;
	}

	if (status->flag & RX_FLAG_MMIC_ERROR)
		goto mic_fail;

	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	if (skb->len < hdrlen + MICHAEL_MIC_LEN)
		return RX_DROP_UNUSABLE;

	if (skb_linearize(rx->skb))
		return RX_DROP_UNUSABLE;
	hdr = (void *)skb->data;

	data = skb->data + hdrlen;
	data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
	key = &rx->key->conf.key[NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY];
	michael_mic(key, hdr, data, data_len, mic);
	if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0)
		goto mic_fail;

	/* remove Michael MIC from payload */
	skb_trim(skb, skb->len - MICHAEL_MIC_LEN);

update_iv:
	/* update IV in key information to be able to detect replays */
	rx->key->u.tkip.rx[rx->security_idx].iv32 = rx->tkip_iv32;
	rx->key->u.tkip.rx[rx->security_idx].iv16 = rx->tkip_iv16;

	return RX_CONTINUE;

mic_fail:
	/*
	 * In some cases the key can be unset - e.g. a multicast packet, in
	 * a driver that supports HW encryption. Send up the key idx only if
	 * the key is set.
	 */
	mac80211_ev_michael_mic_failure(rx->sdata,
					rx->key ? rx->key->conf.keyidx : -1,
					(void *) skb->data, NULL, GFP_ATOMIC);
	return RX_DROP_UNUSABLE;
}


static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
{
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
	struct ieee80211_key *key = tx->key;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	unsigned long flags;
	unsigned int hdrlen;
	int len, tail;
	u8 *pos;

	if (info->control.hw_key &&
	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
		/* hwaccel - with no need for software-generated IV */
		return 0;
	}

	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	len = skb->len - hdrlen;

	if (info->control.hw_key)
		tail = 0;
	else
		tail = TKIP_ICV_LEN;

	if (WARN_ON(skb_tailroom(skb) < tail ||
		    skb_headroom(skb) < TKIP_IV_LEN))
		return -1;

	pos = skb_push(skb, TKIP_IV_LEN);
	memmove(pos, pos + TKIP_IV_LEN, hdrlen);
	pos += hdrlen;

	/* the HW only needs room for the IV, but not the actual IV */
	if (info->control.hw_key &&
	    (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
		return 0;

	/* Increase IV for the frame */
	spin_lock_irqsave(&key->u.tkip.txlock, flags);
	key->u.tkip.tx.iv16++;
	if (key->u.tkip.tx.iv16 == 0)
		key->u.tkip.tx.iv32++;
	pos = ieee80211_tkip_add_iv(pos, key);
	spin_unlock_irqrestore(&key->u.tkip.txlock, flags);

	/* hwaccel - with software IV */
	if (info->control.hw_key)
		return 0;

	/* Add room for ICV */
	skb_put(skb, TKIP_ICV_LEN);

	return ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
					   key, skb, pos, len);
}


ieee80211_tx_result
ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
{
	struct sk_buff *skb;

	ieee80211_tx_set_protected(tx);

	skb_queue_walk(&tx->skbs, skb) {
		if (tkip_encrypt_skb(tx, skb) < 0)
			return TX_DROP;
	}

	return TX_CONTINUE;
}


ieee80211_rx_result
ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
{
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
	int hdrlen, res, hwaccel = 0;
	struct ieee80211_key *key = rx->key;
	struct sk_buff *skb = rx->skb;
	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);

	hdrlen = ieee80211_hdrlen(hdr->frame_control);

	if (!ieee80211_is_data(hdr->frame_control))
		return RX_CONTINUE;

	if (!rx->sta || skb->len - hdrlen < 12)
		return RX_DROP_UNUSABLE;

	/* it may be possible to optimize this a bit more */
	if (skb_linearize(rx->skb))
		return RX_DROP_UNUSABLE;
	hdr = (void *)skb->data;

	/*
	 * Let TKIP code verify IV, but skip decryption.
	 * In the case where hardware checks the IV as well,
	 * we don't even get here, see ieee80211_rx_h_decrypt()
	 */
	if (status->flag & RX_FLAG_DECRYPTED)
		hwaccel = 1;

	res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
					  key, skb->data + hdrlen,
					  skb->len - hdrlen, rx->sta->sta.addr,
					  hdr->addr1, hwaccel, rx->security_idx,
					  &rx->tkip_iv32,
					  &rx->tkip_iv16);
	if (res != TKIP_DECRYPT_OK)
		return RX_DROP_UNUSABLE;

	/* Trim ICV */
	skb_trim(skb, skb->len - TKIP_ICV_LEN);

	/* Remove IV */
	memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
	skb_pull(skb, TKIP_IV_LEN);

	return RX_CONTINUE;
}


static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
				int encrypted)
{
	__le16 mask_fc;
	int a4_included, mgmt;
	u8 qos_tid;
	u8 *b_0, *aad;
	u16 data_len, len_a;
	unsigned int hdrlen;
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;

	memset(scratch, 0, 6 * AES_BLOCK_SIZE);

	b_0 = scratch + 3 * AES_BLOCK_SIZE;
	aad = scratch + 4 * AES_BLOCK_SIZE;

	/*
	 * Mask FC: zero subtype b4 b5 b6 (if not mgmt)
	 * Retry, PwrMgt, MoreData; set Protected
	 */
	mgmt = ieee80211_is_mgmt(hdr->frame_control);
	mask_fc = hdr->frame_control;
	mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY |
				IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
	if (!mgmt)
		mask_fc &= ~cpu_to_le16(0x0070);
	mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);

	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	len_a = hdrlen - 2;
	a4_included = ieee80211_has_a4(hdr->frame_control);

	if (ieee80211_is_data_qos(hdr->frame_control))
		qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
	else
		qos_tid = 0;

	data_len = skb->len - hdrlen - CCMP_HDR_LEN;
	if (encrypted)
		data_len -= CCMP_MIC_LEN;

	/* First block, b_0 */
	b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
	/* Nonce: Nonce Flags | A2 | PN
	 * Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7)
	 */
	b_0[1] = qos_tid | (mgmt << 4);
	memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
	memcpy(&b_0[8], pn, CCMP_PN_LEN);
	/* l(m) */
	put_unaligned_be16(data_len, &b_0[14]);

	/* AAD (extra authenticate-only data) / masked 802.11 header
	 * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
	put_unaligned_be16(len_a, &aad[0]);
	put_unaligned(mask_fc, (__le16 *)&aad[2]);
	memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);

	/* Mask Seq#, leave Frag# */
	aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
	aad[23] = 0;

	if (a4_included) {
		memcpy(&aad[24], hdr->addr4, ETH_ALEN);
		aad[30] = qos_tid;
		aad[31] = 0;
	} else {
		memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
		aad[24] = qos_tid;
	}
}


static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
{
	hdr[0] = pn[5];
	hdr[1] = pn[4];
	hdr[2] = 0;
	hdr[3] = 0x20 | (key_id << 6);
	hdr[4] = pn[3];
	hdr[5] = pn[2];
	hdr[6] = pn[1];
	hdr[7] = pn[0];
}


static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr)
{
	pn[0] = hdr[7];
	pn[1] = hdr[6];
	pn[2] = hdr[5];
	pn[3] = hdr[4];
	pn[4] = hdr[1];
	pn[5] = hdr[0];
}


static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
{
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
	struct ieee80211_key *key = tx->key;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	int hdrlen, len, tail;
	u8 *pos;
	u8 pn[6];
	u64 pn64;
	u8 scratch[6 * AES_BLOCK_SIZE];

	if (info->control.hw_key &&
	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
		/*
		 * hwaccel has no need for preallocated room for CCMP
		 * header or MIC fields
		 */
		return 0;
	}

	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	len = skb->len - hdrlen;

	if (info->control.hw_key)
		tail = 0;
	else
		tail = CCMP_MIC_LEN;

	if (WARN_ON(skb_tailroom(skb) < tail ||
		    skb_headroom(skb) < CCMP_HDR_LEN))
		return -1;

	pos = skb_push(skb, CCMP_HDR_LEN);
	memmove(pos, pos + CCMP_HDR_LEN, hdrlen);

	/* the HW only needs room for the IV, but not the actual IV */
	if (info->control.hw_key &&
	    (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
		return 0;

	hdr = (struct ieee80211_hdr *) pos;
	pos += hdrlen;

	pn64 = atomic64_inc_return(&key->u.ccmp.tx_pn);

	pn[5] = pn64;
	pn[4] = pn64 >> 8;
	pn[3] = pn64 >> 16;
	pn[2] = pn64 >> 24;
	pn[1] = pn64 >> 32;
	pn[0] = pn64 >> 40;

	ccmp_pn2hdr(pos, pn, key->conf.keyidx);

	/* hwaccel - with software CCMP header */
	if (info->control.hw_key)
		return 0;

	pos += CCMP_HDR_LEN;
	ccmp_special_blocks(skb, pn, scratch, 0);
	ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, scratch, pos, len,
				  pos, skb_put(skb, CCMP_MIC_LEN));

	return 0;
}


ieee80211_tx_result
ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
{
	struct sk_buff *skb;

	ieee80211_tx_set_protected(tx);

	skb_queue_walk(&tx->skbs, skb) {
		if (ccmp_encrypt_skb(tx, skb) < 0)
			return TX_DROP;
	}

	return TX_CONTINUE;
}


ieee80211_rx_result
ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
{
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
	int hdrlen;
	struct ieee80211_key *key = rx->key;
	struct sk_buff *skb = rx->skb;
	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
	u8 pn[CCMP_PN_LEN];
	int data_len;
	int queue;

	hdrlen = ieee80211_hdrlen(hdr->frame_control);

	if (!ieee80211_is_data(hdr->frame_control) &&
	    !ieee80211_is_robust_mgmt_frame(hdr))
		return RX_CONTINUE;

	data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
	if (!rx->sta || data_len < 0)
		return RX_DROP_UNUSABLE;

	if (status->flag & RX_FLAG_DECRYPTED) {
		if (!pskb_may_pull(rx->skb, hdrlen + CCMP_HDR_LEN))
			return RX_DROP_UNUSABLE;
	} else {
		if (skb_linearize(rx->skb))
			return RX_DROP_UNUSABLE;
	}

	ccmp_hdr2pn(pn, skb->data + hdrlen);

	queue = rx->security_idx;

	if (memcmp(pn, key->u.ccmp.rx_pn[queue], CCMP_PN_LEN) <= 0) {
		key->u.ccmp.replays++;
		return RX_DROP_UNUSABLE;
	}

	if (!(status->flag & RX_FLAG_DECRYPTED)) {
		u8 scratch[6 * AES_BLOCK_SIZE];
		/* hardware didn't decrypt/verify MIC */
		ccmp_special_blocks(skb, pn, scratch, 1);

		if (ieee80211_aes_ccm_decrypt(
			    key->u.ccmp.tfm, scratch,
			    skb->data + hdrlen + CCMP_HDR_LEN, data_len,
			    skb->data + skb->len - CCMP_MIC_LEN,
			    skb->data + hdrlen + CCMP_HDR_LEN))
			return RX_DROP_UNUSABLE;
	}

	memcpy(key->u.ccmp.rx_pn[queue], pn, CCMP_PN_LEN);

	/* Remove CCMP header and MIC */
	if (pskb_trim(skb, skb->len - CCMP_MIC_LEN))
		return RX_DROP_UNUSABLE;
	memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
	skb_pull(skb, CCMP_HDR_LEN);

	return RX_CONTINUE;
}


static void bip_aad(struct sk_buff *skb, u8 *aad)
{
	/* BIP AAD: FC(masked) || A1 || A2 || A3 */

	/* FC type/subtype */
	aad[0] = skb->data[0];
	/* Mask FC Retry, PwrMgt, MoreData flags to zero */
	aad[1] = skb->data[1] & ~(BIT(4) | BIT(5) | BIT(6));
	/* A1 || A2 || A3 */
	memcpy(aad + 2, skb->data + 4, 3 * ETH_ALEN);
}


static inline void bip_ipn_set64(u8 *d, u64 pn)
{
	*d++ = pn;
	*d++ = pn >> 8;
	*d++ = pn >> 16;
	*d++ = pn >> 24;
	*d++ = pn >> 32;
	*d = pn >> 40;
}

static inline void bip_ipn_swap(u8 *d, const u8 *s)
{
	*d++ = s[5];
	*d++ = s[4];
	*d++ = s[3];
	*d++ = s[2];
	*d++ = s[1];
	*d = s[0];
}


ieee80211_tx_result
ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
{
	struct sk_buff *skb;
	struct ieee80211_tx_info *info;
	struct ieee80211_key *key = tx->key;
	struct ieee80211_mmie *mmie;
	u8 aad[20];
	u64 pn64;

	if (WARN_ON(skb_queue_len(&tx->skbs) != 1))
		return TX_DROP;

	skb = skb_peek(&tx->skbs);

	info = IEEE80211_SKB_CB(skb);

	if (info->control.hw_key)
		return TX_CONTINUE;

	if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie)))
		return TX_DROP;

	mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie));
	mmie->element_id = WLAN_EID_MMIE;
	mmie->length = sizeof(*mmie) - 2;
	mmie->key_id = cpu_to_le16(key->conf.keyidx);

	/* PN = PN + 1 */
	pn64 = atomic64_inc_return(&key->u.aes_cmac.tx_pn);

	bip_ipn_set64(mmie->sequence_number, pn64);

	bip_aad(skb, aad);

	/*
	 * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64)
	 */
	ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
			   skb->data + 24, skb->len - 24, mmie->mic);

	return TX_CONTINUE;
}


ieee80211_rx_result
ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
{
	struct sk_buff *skb = rx->skb;
	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
	struct ieee80211_key *key = rx->key;
	struct ieee80211_mmie *mmie;
	u8 aad[20], mic[8], ipn[6];
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;

	if (!ieee80211_is_mgmt(hdr->frame_control))
		return RX_CONTINUE;

	/* management frames are already linear */

	if (skb->len < 24 + sizeof(*mmie))
		return RX_DROP_UNUSABLE;

	mmie = (struct ieee80211_mmie *)
		(skb->data + skb->len - sizeof(*mmie));
	if (mmie->element_id != WLAN_EID_MMIE ||
	    mmie->length != sizeof(*mmie) - 2)
		return RX_DROP_UNUSABLE; /* Invalid MMIE */

	bip_ipn_swap(ipn, mmie->sequence_number);

	if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) {
		key->u.aes_cmac.replays++;
		return RX_DROP_UNUSABLE;
	}

	if (!(status->flag & RX_FLAG_DECRYPTED)) {
		/* hardware didn't decrypt/verify MIC */
		bip_aad(skb, aad);
		ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
				   skb->data + 24, skb->len - 24, mic);
		if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
			key->u.aes_cmac.icverrors++;
			return RX_DROP_UNUSABLE;
		}
	}

	memcpy(key->u.aes_cmac.rx_pn, ipn, 6);

	/* Remove MMIE */
	skb_trim(skb, skb->len - sizeof(*mmie));

	return RX_CONTINUE;
}

ieee80211_tx_result
ieee80211_crypto_hw_encrypt(struct ieee80211_tx_data *tx)
{
	struct sk_buff *skb;
	struct ieee80211_tx_info *info = NULL;

	skb_queue_walk(&tx->skbs, skb) {
		info  = IEEE80211_SKB_CB(skb);

		/* handle hw-only algorithm */
		if (!info->control.hw_key)
			return TX_DROP;
	}

	ieee80211_tx_set_protected(tx);

	return TX_CONTINUE;
}