xref: /openbmc/linux/net/mac80211/wpa.c (revision 9d749629)
1 /*
2  * Copyright 2002-2004, Instant802 Networks, Inc.
3  * Copyright 2008, Jouni Malinen <j@w1.fi>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  */
9 
10 #include <linux/netdevice.h>
11 #include <linux/types.h>
12 #include <linux/skbuff.h>
13 #include <linux/compiler.h>
14 #include <linux/ieee80211.h>
15 #include <linux/gfp.h>
16 #include <asm/unaligned.h>
17 #include <net/mac80211.h>
18 #include <crypto/aes.h>
19 
20 #include "ieee80211_i.h"
21 #include "michael.h"
22 #include "tkip.h"
23 #include "aes_ccm.h"
24 #include "aes_cmac.h"
25 #include "wpa.h"
26 
27 ieee80211_tx_result
28 ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
29 {
30 	u8 *data, *key, *mic;
31 	size_t data_len;
32 	unsigned int hdrlen;
33 	struct ieee80211_hdr *hdr;
34 	struct sk_buff *skb = tx->skb;
35 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
36 	int tail;
37 
38 	hdr = (struct ieee80211_hdr *)skb->data;
39 	if (!tx->key || tx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP ||
40 	    skb->len < 24 || !ieee80211_is_data_present(hdr->frame_control))
41 		return TX_CONTINUE;
42 
43 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
44 	if (skb->len < hdrlen)
45 		return TX_DROP;
46 
47 	data = skb->data + hdrlen;
48 	data_len = skb->len - hdrlen;
49 
50 	if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE)) {
51 		/* Need to use software crypto for the test */
52 		info->control.hw_key = NULL;
53 	}
54 
55 	if (info->control.hw_key &&
56 	    (info->flags & IEEE80211_TX_CTL_DONTFRAG ||
57 	     tx->local->ops->set_frag_threshold) &&
58 	    !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
59 		/* hwaccel - with no need for SW-generated MMIC */
60 		return TX_CONTINUE;
61 	}
62 
63 	tail = MICHAEL_MIC_LEN;
64 	if (!info->control.hw_key)
65 		tail += TKIP_ICV_LEN;
66 
67 	if (WARN_ON(skb_tailroom(skb) < tail ||
68 		    skb_headroom(skb) < TKIP_IV_LEN))
69 		return TX_DROP;
70 
71 	key = &tx->key->conf.key[NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY];
72 	mic = skb_put(skb, MICHAEL_MIC_LEN);
73 	michael_mic(key, hdr, data, data_len, mic);
74 	if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE))
75 		mic[0]++;
76 
77 	return TX_CONTINUE;
78 }
79 
80 
81 ieee80211_rx_result
82 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
83 {
84 	u8 *data, *key = NULL;
85 	size_t data_len;
86 	unsigned int hdrlen;
87 	u8 mic[MICHAEL_MIC_LEN];
88 	struct sk_buff *skb = rx->skb;
89 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
90 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
91 
92 	/*
93 	 * it makes no sense to check for MIC errors on anything other
94 	 * than data frames.
95 	 */
96 	if (!ieee80211_is_data_present(hdr->frame_control))
97 		return RX_CONTINUE;
98 
99 	/*
100 	 * No way to verify the MIC if the hardware stripped it or
101 	 * the IV with the key index. In this case we have solely rely
102 	 * on the driver to set RX_FLAG_MMIC_ERROR in the event of a
103 	 * MIC failure report.
104 	 */
105 	if (status->flag & (RX_FLAG_MMIC_STRIPPED | RX_FLAG_IV_STRIPPED)) {
106 		if (status->flag & RX_FLAG_MMIC_ERROR)
107 			goto mic_fail_no_key;
108 
109 		if (!(status->flag & RX_FLAG_IV_STRIPPED) && rx->key &&
110 		    rx->key->conf.cipher == WLAN_CIPHER_SUITE_TKIP)
111 			goto update_iv;
112 
113 		return RX_CONTINUE;
114 	}
115 
116 	/*
117 	 * Some hardware seems to generate Michael MIC failure reports; even
118 	 * though, the frame was not encrypted with TKIP and therefore has no
119 	 * MIC. Ignore the flag them to avoid triggering countermeasures.
120 	 */
121 	if (!rx->key || rx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP ||
122 	    !(status->flag & RX_FLAG_DECRYPTED))
123 		return RX_CONTINUE;
124 
125 	if (rx->sdata->vif.type == NL80211_IFTYPE_AP && rx->key->conf.keyidx) {
126 		/*
127 		 * APs with pairwise keys should never receive Michael MIC
128 		 * errors for non-zero keyidx because these are reserved for
129 		 * group keys and only the AP is sending real multicast
130 		 * frames in the BSS. (
131 		 */
132 		return RX_DROP_UNUSABLE;
133 	}
134 
135 	if (status->flag & RX_FLAG_MMIC_ERROR)
136 		goto mic_fail;
137 
138 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
139 	if (skb->len < hdrlen + MICHAEL_MIC_LEN)
140 		return RX_DROP_UNUSABLE;
141 
142 	if (skb_linearize(rx->skb))
143 		return RX_DROP_UNUSABLE;
144 	hdr = (void *)skb->data;
145 
146 	data = skb->data + hdrlen;
147 	data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
148 	key = &rx->key->conf.key[NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY];
149 	michael_mic(key, hdr, data, data_len, mic);
150 	if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0)
151 		goto mic_fail;
152 
153 	/* remove Michael MIC from payload */
154 	skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
155 
156 update_iv:
157 	/* update IV in key information to be able to detect replays */
158 	rx->key->u.tkip.rx[rx->security_idx].iv32 = rx->tkip_iv32;
159 	rx->key->u.tkip.rx[rx->security_idx].iv16 = rx->tkip_iv16;
160 
161 	return RX_CONTINUE;
162 
163 mic_fail:
164 	rx->key->u.tkip.mic_failures++;
165 
166 mic_fail_no_key:
167 	/*
168 	 * In some cases the key can be unset - e.g. a multicast packet, in
169 	 * a driver that supports HW encryption. Send up the key idx only if
170 	 * the key is set.
171 	 */
172 	mac80211_ev_michael_mic_failure(rx->sdata,
173 					rx->key ? rx->key->conf.keyidx : -1,
174 					(void *) skb->data, NULL, GFP_ATOMIC);
175 	return RX_DROP_UNUSABLE;
176 }
177 
178 
179 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
180 {
181 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
182 	struct ieee80211_key *key = tx->key;
183 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
184 	unsigned int hdrlen;
185 	int len, tail;
186 	u8 *pos;
187 
188 	if (info->control.hw_key &&
189 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
190 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
191 		/* hwaccel - with no need for software-generated IV */
192 		return 0;
193 	}
194 
195 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
196 	len = skb->len - hdrlen;
197 
198 	if (info->control.hw_key)
199 		tail = 0;
200 	else
201 		tail = TKIP_ICV_LEN;
202 
203 	if (WARN_ON(skb_tailroom(skb) < tail ||
204 		    skb_headroom(skb) < TKIP_IV_LEN))
205 		return -1;
206 
207 	pos = skb_push(skb, TKIP_IV_LEN);
208 	memmove(pos, pos + TKIP_IV_LEN, hdrlen);
209 	skb_set_network_header(skb, skb_network_offset(skb) + TKIP_IV_LEN);
210 	pos += hdrlen;
211 
212 	/* the HW only needs room for the IV, but not the actual IV */
213 	if (info->control.hw_key &&
214 	    (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
215 		return 0;
216 
217 	/* Increase IV for the frame */
218 	spin_lock(&key->u.tkip.txlock);
219 	key->u.tkip.tx.iv16++;
220 	if (key->u.tkip.tx.iv16 == 0)
221 		key->u.tkip.tx.iv32++;
222 	pos = ieee80211_tkip_add_iv(pos, key);
223 	spin_unlock(&key->u.tkip.txlock);
224 
225 	/* hwaccel - with software IV */
226 	if (info->control.hw_key)
227 		return 0;
228 
229 	/* Add room for ICV */
230 	skb_put(skb, TKIP_ICV_LEN);
231 
232 	return ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
233 					   key, skb, pos, len);
234 }
235 
236 
237 ieee80211_tx_result
238 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
239 {
240 	struct sk_buff *skb;
241 
242 	ieee80211_tx_set_protected(tx);
243 
244 	skb_queue_walk(&tx->skbs, skb) {
245 		if (tkip_encrypt_skb(tx, skb) < 0)
246 			return TX_DROP;
247 	}
248 
249 	return TX_CONTINUE;
250 }
251 
252 
253 ieee80211_rx_result
254 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
255 {
256 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
257 	int hdrlen, res, hwaccel = 0;
258 	struct ieee80211_key *key = rx->key;
259 	struct sk_buff *skb = rx->skb;
260 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
261 
262 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
263 
264 	if (!ieee80211_is_data(hdr->frame_control))
265 		return RX_CONTINUE;
266 
267 	if (!rx->sta || skb->len - hdrlen < 12)
268 		return RX_DROP_UNUSABLE;
269 
270 	/* it may be possible to optimize this a bit more */
271 	if (skb_linearize(rx->skb))
272 		return RX_DROP_UNUSABLE;
273 	hdr = (void *)skb->data;
274 
275 	/*
276 	 * Let TKIP code verify IV, but skip decryption.
277 	 * In the case where hardware checks the IV as well,
278 	 * we don't even get here, see ieee80211_rx_h_decrypt()
279 	 */
280 	if (status->flag & RX_FLAG_DECRYPTED)
281 		hwaccel = 1;
282 
283 	res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
284 					  key, skb->data + hdrlen,
285 					  skb->len - hdrlen, rx->sta->sta.addr,
286 					  hdr->addr1, hwaccel, rx->security_idx,
287 					  &rx->tkip_iv32,
288 					  &rx->tkip_iv16);
289 	if (res != TKIP_DECRYPT_OK)
290 		return RX_DROP_UNUSABLE;
291 
292 	/* Trim ICV */
293 	skb_trim(skb, skb->len - TKIP_ICV_LEN);
294 
295 	/* Remove IV */
296 	memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
297 	skb_pull(skb, TKIP_IV_LEN);
298 
299 	return RX_CONTINUE;
300 }
301 
302 
303 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
304 				int encrypted)
305 {
306 	__le16 mask_fc;
307 	int a4_included, mgmt;
308 	u8 qos_tid;
309 	u8 *b_0, *aad;
310 	u16 data_len, len_a;
311 	unsigned int hdrlen;
312 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
313 
314 	memset(scratch, 0, 6 * AES_BLOCK_SIZE);
315 
316 	b_0 = scratch + 3 * AES_BLOCK_SIZE;
317 	aad = scratch + 4 * AES_BLOCK_SIZE;
318 
319 	/*
320 	 * Mask FC: zero subtype b4 b5 b6 (if not mgmt)
321 	 * Retry, PwrMgt, MoreData; set Protected
322 	 */
323 	mgmt = ieee80211_is_mgmt(hdr->frame_control);
324 	mask_fc = hdr->frame_control;
325 	mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY |
326 				IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
327 	if (!mgmt)
328 		mask_fc &= ~cpu_to_le16(0x0070);
329 	mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
330 
331 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
332 	len_a = hdrlen - 2;
333 	a4_included = ieee80211_has_a4(hdr->frame_control);
334 
335 	if (ieee80211_is_data_qos(hdr->frame_control))
336 		qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
337 	else
338 		qos_tid = 0;
339 
340 	data_len = skb->len - hdrlen - CCMP_HDR_LEN;
341 	if (encrypted)
342 		data_len -= CCMP_MIC_LEN;
343 
344 	/* First block, b_0 */
345 	b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
346 	/* Nonce: Nonce Flags | A2 | PN
347 	 * Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7)
348 	 */
349 	b_0[1] = qos_tid | (mgmt << 4);
350 	memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
351 	memcpy(&b_0[8], pn, CCMP_PN_LEN);
352 	/* l(m) */
353 	put_unaligned_be16(data_len, &b_0[14]);
354 
355 	/* AAD (extra authenticate-only data) / masked 802.11 header
356 	 * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
357 	put_unaligned_be16(len_a, &aad[0]);
358 	put_unaligned(mask_fc, (__le16 *)&aad[2]);
359 	memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
360 
361 	/* Mask Seq#, leave Frag# */
362 	aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
363 	aad[23] = 0;
364 
365 	if (a4_included) {
366 		memcpy(&aad[24], hdr->addr4, ETH_ALEN);
367 		aad[30] = qos_tid;
368 		aad[31] = 0;
369 	} else {
370 		memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
371 		aad[24] = qos_tid;
372 	}
373 }
374 
375 
376 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
377 {
378 	hdr[0] = pn[5];
379 	hdr[1] = pn[4];
380 	hdr[2] = 0;
381 	hdr[3] = 0x20 | (key_id << 6);
382 	hdr[4] = pn[3];
383 	hdr[5] = pn[2];
384 	hdr[6] = pn[1];
385 	hdr[7] = pn[0];
386 }
387 
388 
389 static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr)
390 {
391 	pn[0] = hdr[7];
392 	pn[1] = hdr[6];
393 	pn[2] = hdr[5];
394 	pn[3] = hdr[4];
395 	pn[4] = hdr[1];
396 	pn[5] = hdr[0];
397 }
398 
399 
400 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
401 {
402 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
403 	struct ieee80211_key *key = tx->key;
404 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
405 	int hdrlen, len, tail;
406 	u8 *pos;
407 	u8 pn[6];
408 	u64 pn64;
409 	u8 scratch[6 * AES_BLOCK_SIZE];
410 
411 	if (info->control.hw_key &&
412 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
413 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
414 		/*
415 		 * hwaccel has no need for preallocated room for CCMP
416 		 * header or MIC fields
417 		 */
418 		return 0;
419 	}
420 
421 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
422 	len = skb->len - hdrlen;
423 
424 	if (info->control.hw_key)
425 		tail = 0;
426 	else
427 		tail = CCMP_MIC_LEN;
428 
429 	if (WARN_ON(skb_tailroom(skb) < tail ||
430 		    skb_headroom(skb) < CCMP_HDR_LEN))
431 		return -1;
432 
433 	pos = skb_push(skb, CCMP_HDR_LEN);
434 	memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
435 	skb_set_network_header(skb, skb_network_offset(skb) + CCMP_HDR_LEN);
436 
437 	/* the HW only needs room for the IV, but not the actual IV */
438 	if (info->control.hw_key &&
439 	    (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
440 		return 0;
441 
442 	hdr = (struct ieee80211_hdr *) pos;
443 	pos += hdrlen;
444 
445 	pn64 = atomic64_inc_return(&key->u.ccmp.tx_pn);
446 
447 	pn[5] = pn64;
448 	pn[4] = pn64 >> 8;
449 	pn[3] = pn64 >> 16;
450 	pn[2] = pn64 >> 24;
451 	pn[1] = pn64 >> 32;
452 	pn[0] = pn64 >> 40;
453 
454 	ccmp_pn2hdr(pos, pn, key->conf.keyidx);
455 
456 	/* hwaccel - with software CCMP header */
457 	if (info->control.hw_key)
458 		return 0;
459 
460 	pos += CCMP_HDR_LEN;
461 	ccmp_special_blocks(skb, pn, scratch, 0);
462 	ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, scratch, pos, len,
463 				  pos, skb_put(skb, CCMP_MIC_LEN));
464 
465 	return 0;
466 }
467 
468 
469 ieee80211_tx_result
470 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
471 {
472 	struct sk_buff *skb;
473 
474 	ieee80211_tx_set_protected(tx);
475 
476 	skb_queue_walk(&tx->skbs, skb) {
477 		if (ccmp_encrypt_skb(tx, skb) < 0)
478 			return TX_DROP;
479 	}
480 
481 	return TX_CONTINUE;
482 }
483 
484 
485 ieee80211_rx_result
486 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
487 {
488 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
489 	int hdrlen;
490 	struct ieee80211_key *key = rx->key;
491 	struct sk_buff *skb = rx->skb;
492 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
493 	u8 pn[CCMP_PN_LEN];
494 	int data_len;
495 	int queue;
496 
497 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
498 
499 	if (!ieee80211_is_data(hdr->frame_control) &&
500 	    !ieee80211_is_robust_mgmt_frame(hdr))
501 		return RX_CONTINUE;
502 
503 	data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
504 	if (!rx->sta || data_len < 0)
505 		return RX_DROP_UNUSABLE;
506 
507 	if (status->flag & RX_FLAG_DECRYPTED) {
508 		if (!pskb_may_pull(rx->skb, hdrlen + CCMP_HDR_LEN))
509 			return RX_DROP_UNUSABLE;
510 	} else {
511 		if (skb_linearize(rx->skb))
512 			return RX_DROP_UNUSABLE;
513 	}
514 
515 	ccmp_hdr2pn(pn, skb->data + hdrlen);
516 
517 	queue = rx->security_idx;
518 
519 	if (memcmp(pn, key->u.ccmp.rx_pn[queue], CCMP_PN_LEN) <= 0) {
520 		key->u.ccmp.replays++;
521 		return RX_DROP_UNUSABLE;
522 	}
523 
524 	if (!(status->flag & RX_FLAG_DECRYPTED)) {
525 		u8 scratch[6 * AES_BLOCK_SIZE];
526 		/* hardware didn't decrypt/verify MIC */
527 		ccmp_special_blocks(skb, pn, scratch, 1);
528 
529 		if (ieee80211_aes_ccm_decrypt(
530 			    key->u.ccmp.tfm, scratch,
531 			    skb->data + hdrlen + CCMP_HDR_LEN, data_len,
532 			    skb->data + skb->len - CCMP_MIC_LEN,
533 			    skb->data + hdrlen + CCMP_HDR_LEN))
534 			return RX_DROP_UNUSABLE;
535 	}
536 
537 	memcpy(key->u.ccmp.rx_pn[queue], pn, CCMP_PN_LEN);
538 
539 	/* Remove CCMP header and MIC */
540 	if (pskb_trim(skb, skb->len - CCMP_MIC_LEN))
541 		return RX_DROP_UNUSABLE;
542 	memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
543 	skb_pull(skb, CCMP_HDR_LEN);
544 
545 	return RX_CONTINUE;
546 }
547 
548 
549 static void bip_aad(struct sk_buff *skb, u8 *aad)
550 {
551 	__le16 mask_fc;
552 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
553 
554 	/* BIP AAD: FC(masked) || A1 || A2 || A3 */
555 
556 	/* FC type/subtype */
557 	/* Mask FC Retry, PwrMgt, MoreData flags to zero */
558 	mask_fc = hdr->frame_control;
559 	mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY | IEEE80211_FCTL_PM |
560 				IEEE80211_FCTL_MOREDATA);
561 	put_unaligned(mask_fc, (__le16 *) &aad[0]);
562 	/* A1 || A2 || A3 */
563 	memcpy(aad + 2, &hdr->addr1, 3 * ETH_ALEN);
564 }
565 
566 
567 static inline void bip_ipn_set64(u8 *d, u64 pn)
568 {
569 	*d++ = pn;
570 	*d++ = pn >> 8;
571 	*d++ = pn >> 16;
572 	*d++ = pn >> 24;
573 	*d++ = pn >> 32;
574 	*d = pn >> 40;
575 }
576 
577 static inline void bip_ipn_swap(u8 *d, const u8 *s)
578 {
579 	*d++ = s[5];
580 	*d++ = s[4];
581 	*d++ = s[3];
582 	*d++ = s[2];
583 	*d++ = s[1];
584 	*d = s[0];
585 }
586 
587 
588 ieee80211_tx_result
589 ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
590 {
591 	struct sk_buff *skb;
592 	struct ieee80211_tx_info *info;
593 	struct ieee80211_key *key = tx->key;
594 	struct ieee80211_mmie *mmie;
595 	u8 aad[20];
596 	u64 pn64;
597 
598 	if (WARN_ON(skb_queue_len(&tx->skbs) != 1))
599 		return TX_DROP;
600 
601 	skb = skb_peek(&tx->skbs);
602 
603 	info = IEEE80211_SKB_CB(skb);
604 
605 	if (info->control.hw_key)
606 		return TX_CONTINUE;
607 
608 	if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie)))
609 		return TX_DROP;
610 
611 	mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie));
612 	mmie->element_id = WLAN_EID_MMIE;
613 	mmie->length = sizeof(*mmie) - 2;
614 	mmie->key_id = cpu_to_le16(key->conf.keyidx);
615 
616 	/* PN = PN + 1 */
617 	pn64 = atomic64_inc_return(&key->u.aes_cmac.tx_pn);
618 
619 	bip_ipn_set64(mmie->sequence_number, pn64);
620 
621 	bip_aad(skb, aad);
622 
623 	/*
624 	 * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64)
625 	 */
626 	ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
627 			   skb->data + 24, skb->len - 24, mmie->mic);
628 
629 	return TX_CONTINUE;
630 }
631 
632 
633 ieee80211_rx_result
634 ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
635 {
636 	struct sk_buff *skb = rx->skb;
637 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
638 	struct ieee80211_key *key = rx->key;
639 	struct ieee80211_mmie *mmie;
640 	u8 aad[20], mic[8], ipn[6];
641 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
642 
643 	if (!ieee80211_is_mgmt(hdr->frame_control))
644 		return RX_CONTINUE;
645 
646 	/* management frames are already linear */
647 
648 	if (skb->len < 24 + sizeof(*mmie))
649 		return RX_DROP_UNUSABLE;
650 
651 	mmie = (struct ieee80211_mmie *)
652 		(skb->data + skb->len - sizeof(*mmie));
653 	if (mmie->element_id != WLAN_EID_MMIE ||
654 	    mmie->length != sizeof(*mmie) - 2)
655 		return RX_DROP_UNUSABLE; /* Invalid MMIE */
656 
657 	bip_ipn_swap(ipn, mmie->sequence_number);
658 
659 	if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) {
660 		key->u.aes_cmac.replays++;
661 		return RX_DROP_UNUSABLE;
662 	}
663 
664 	if (!(status->flag & RX_FLAG_DECRYPTED)) {
665 		/* hardware didn't decrypt/verify MIC */
666 		bip_aad(skb, aad);
667 		ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
668 				   skb->data + 24, skb->len - 24, mic);
669 		if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
670 			key->u.aes_cmac.icverrors++;
671 			return RX_DROP_UNUSABLE;
672 		}
673 	}
674 
675 	memcpy(key->u.aes_cmac.rx_pn, ipn, 6);
676 
677 	/* Remove MMIE */
678 	skb_trim(skb, skb->len - sizeof(*mmie));
679 
680 	return RX_CONTINUE;
681 }
682 
683 ieee80211_tx_result
684 ieee80211_crypto_hw_encrypt(struct ieee80211_tx_data *tx)
685 {
686 	struct sk_buff *skb;
687 	struct ieee80211_tx_info *info = NULL;
688 
689 	skb_queue_walk(&tx->skbs, skb) {
690 		info  = IEEE80211_SKB_CB(skb);
691 
692 		/* handle hw-only algorithm */
693 		if (!info->control.hw_key)
694 			return TX_DROP;
695 	}
696 
697 	ieee80211_tx_set_protected(tx);
698 
699 	return TX_CONTINUE;
700 }
701