xref: /openbmc/linux/net/mac80211/wpa.c (revision fd589a8f) 
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/slab.h>
13 #include <linux/skbuff.h>
14 #include <linux/compiler.h>
15 #include <linux/ieee80211.h>
16 #include <asm/unaligned.h>
17 #include <net/mac80211.h>
18 
19 #include "ieee80211_i.h"
20 #include "michael.h"
21 #include "tkip.h"
22 #include "aes_ccm.h"
23 #include "aes_cmac.h"
24 #include "wpa.h"
25 
26 ieee80211_tx_result
27 ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
28 {
29 	u8 *data, *key, *mic, key_offset;
30 	size_t data_len;
31 	unsigned int hdrlen;
32 	struct ieee80211_hdr *hdr;
33 	struct sk_buff *skb = tx->skb;
34 	int authenticator;
35 	int wpa_test = 0;
36 	int tail;
37 
38 	hdr = (struct ieee80211_hdr *)skb->data;
39 	if (!tx->key || tx->key->conf.alg != ALG_TKIP || skb->len < 24 ||
40 	    !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 ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
51 	    !(tx->flags & IEEE80211_TX_FRAGMENTED) &&
52 	    !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) &&
53 	    !wpa_test) {
54 		/* hwaccel - with no need for preallocated room for MMIC */
55 		return TX_CONTINUE;
56 	}
57 
58 	tail = MICHAEL_MIC_LEN;
59 	if (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
60 		tail += TKIP_ICV_LEN;
61 
62 	if (WARN_ON(skb_tailroom(skb) < tail ||
63 		    skb_headroom(skb) < TKIP_IV_LEN))
64 		return TX_DROP;
65 
66 #if 0
67 	authenticator = fc & IEEE80211_FCTL_FROMDS; /* FIX */
68 #else
69 	authenticator = 1;
70 #endif
71 	key_offset = authenticator ?
72 		NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY :
73 		NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY;
74 	key = &tx->key->conf.key[key_offset];
75 	mic = skb_put(skb, MICHAEL_MIC_LEN);
76 	michael_mic(key, hdr, data, data_len, mic);
77 
78 	return TX_CONTINUE;
79 }
80 
81 
82 ieee80211_rx_result
83 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
84 {
85 	u8 *data, *key = NULL, key_offset;
86 	size_t data_len;
87 	unsigned int hdrlen;
88 	struct ieee80211_hdr *hdr;
89 	u8 mic[MICHAEL_MIC_LEN];
90 	struct sk_buff *skb = rx->skb;
91 	int authenticator = 1, wpa_test = 0;
92 
93 	/* No way to verify the MIC if the hardware stripped it */
94 	if (rx->status->flag & RX_FLAG_MMIC_STRIPPED)
95 		return RX_CONTINUE;
96 
97 	hdr = (struct ieee80211_hdr *)skb->data;
98 	if (!rx->key || rx->key->conf.alg != ALG_TKIP ||
99 	    !ieee80211_has_protected(hdr->frame_control) ||
100 	    !ieee80211_is_data_present(hdr->frame_control))
101 		return RX_CONTINUE;
102 
103 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
104 	if (skb->len < hdrlen + MICHAEL_MIC_LEN)
105 		return RX_DROP_UNUSABLE;
106 
107 	data = skb->data + hdrlen;
108 	data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
109 
110 #if 0
111 	authenticator = fc & IEEE80211_FCTL_TODS; /* FIX */
112 #else
113 	authenticator = 1;
114 #endif
115 	key_offset = authenticator ?
116 		NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY :
117 		NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY;
118 	key = &rx->key->conf.key[key_offset];
119 	michael_mic(key, hdr, data, data_len, mic);
120 	if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0 || wpa_test) {
121 		if (!(rx->flags & IEEE80211_RX_RA_MATCH))
122 			return RX_DROP_UNUSABLE;
123 
124 		mac80211_ev_michael_mic_failure(rx->sdata, rx->key->conf.keyidx,
125 						(void *) skb->data, NULL,
126 						GFP_ATOMIC);
127 		return RX_DROP_UNUSABLE;
128 	}
129 
130 	/* remove Michael MIC from payload */
131 	skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
132 
133 	/* update IV in key information to be able to detect replays */
134 	rx->key->u.tkip.rx[rx->queue].iv32 = rx->tkip_iv32;
135 	rx->key->u.tkip.rx[rx->queue].iv16 = rx->tkip_iv16;
136 
137 	return RX_CONTINUE;
138 }
139 
140 
141 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
142 {
143 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
144 	struct ieee80211_key *key = tx->key;
145 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
146 	unsigned int hdrlen;
147 	int len, tail;
148 	u8 *pos;
149 
150 	if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
151 	    !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
152 		/* hwaccel - with no need for preallocated room for IV/ICV */
153 		info->control.hw_key = &tx->key->conf;
154 		return 0;
155 	}
156 
157 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
158 	len = skb->len - hdrlen;
159 
160 	if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
161 		tail = 0;
162 	else
163 		tail = TKIP_ICV_LEN;
164 
165 	if (WARN_ON(skb_tailroom(skb) < tail ||
166 		    skb_headroom(skb) < TKIP_IV_LEN))
167 		return -1;
168 
169 	pos = skb_push(skb, TKIP_IV_LEN);
170 	memmove(pos, pos + TKIP_IV_LEN, hdrlen);
171 	pos += hdrlen;
172 
173 	/* Increase IV for the frame */
174 	key->u.tkip.tx.iv16++;
175 	if (key->u.tkip.tx.iv16 == 0)
176 		key->u.tkip.tx.iv32++;
177 
178 	if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
179 		/* hwaccel - with preallocated room for IV */
180 		ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
181 
182 		info->control.hw_key = &tx->key->conf;
183 		return 0;
184 	}
185 
186 	/* Add room for ICV */
187 	skb_put(skb, TKIP_ICV_LEN);
188 
189 	hdr = (struct ieee80211_hdr *) skb->data;
190 	ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
191 				    key, pos, len, hdr->addr2);
192 	return 0;
193 }
194 
195 
196 ieee80211_tx_result
197 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
198 {
199 	struct sk_buff *skb = tx->skb;
200 
201 	ieee80211_tx_set_protected(tx);
202 
203 	do {
204 		if (tkip_encrypt_skb(tx, skb) < 0)
205 			return TX_DROP;
206 	} while ((skb = skb->next));
207 
208 	return TX_CONTINUE;
209 }
210 
211 
212 ieee80211_rx_result
213 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
214 {
215 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
216 	int hdrlen, res, hwaccel = 0, wpa_test = 0;
217 	struct ieee80211_key *key = rx->key;
218 	struct sk_buff *skb = rx->skb;
219 
220 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
221 
222 	if (!ieee80211_is_data(hdr->frame_control))
223 		return RX_CONTINUE;
224 
225 	if (!rx->sta || skb->len - hdrlen < 12)
226 		return RX_DROP_UNUSABLE;
227 
228 	if (rx->status->flag & RX_FLAG_DECRYPTED) {
229 		if (rx->status->flag & RX_FLAG_IV_STRIPPED) {
230 			/*
231 			 * Hardware took care of all processing, including
232 			 * replay protection, and stripped the ICV/IV so
233 			 * we cannot do any checks here.
234 			 */
235 			return RX_CONTINUE;
236 		}
237 
238 		/* let TKIP code verify IV, but skip decryption */
239 		hwaccel = 1;
240 	}
241 
242 	res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
243 					  key, skb->data + hdrlen,
244 					  skb->len - hdrlen, rx->sta->sta.addr,
245 					  hdr->addr1, hwaccel, rx->queue,
246 					  &rx->tkip_iv32,
247 					  &rx->tkip_iv16);
248 	if (res != TKIP_DECRYPT_OK || wpa_test)
249 		return RX_DROP_UNUSABLE;
250 
251 	/* Trim ICV */
252 	skb_trim(skb, skb->len - TKIP_ICV_LEN);
253 
254 	/* Remove IV */
255 	memmove(skb->data + TKIP_IV_LEN, skb->data, hdrlen);
256 	skb_pull(skb, TKIP_IV_LEN);
257 
258 	return RX_CONTINUE;
259 }
260 
261 
262 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
263 				int encrypted)
264 {
265 	__le16 mask_fc;
266 	int a4_included, mgmt;
267 	u8 qos_tid;
268 	u8 *b_0, *aad;
269 	u16 data_len, len_a;
270 	unsigned int hdrlen;
271 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
272 
273 	b_0 = scratch + 3 * AES_BLOCK_LEN;
274 	aad = scratch + 4 * AES_BLOCK_LEN;
275 
276 	/*
277 	 * Mask FC: zero subtype b4 b5 b6 (if not mgmt)
278 	 * Retry, PwrMgt, MoreData; set Protected
279 	 */
280 	mgmt = ieee80211_is_mgmt(hdr->frame_control);
281 	mask_fc = hdr->frame_control;
282 	mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY |
283 				IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
284 	if (!mgmt)
285 		mask_fc &= ~cpu_to_le16(0x0070);
286 	mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
287 
288 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
289 	len_a = hdrlen - 2;
290 	a4_included = ieee80211_has_a4(hdr->frame_control);
291 
292 	if (ieee80211_is_data_qos(hdr->frame_control))
293 		qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
294 	else
295 		qos_tid = 0;
296 
297 	data_len = skb->len - hdrlen - CCMP_HDR_LEN;
298 	if (encrypted)
299 		data_len -= CCMP_MIC_LEN;
300 
301 	/* First block, b_0 */
302 	b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
303 	/* Nonce: Nonce Flags | A2 | PN
304 	 * Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7)
305 	 */
306 	b_0[1] = qos_tid | (mgmt << 4);
307 	memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
308 	memcpy(&b_0[8], pn, CCMP_PN_LEN);
309 	/* l(m) */
310 	put_unaligned_be16(data_len, &b_0[14]);
311 
312 	/* AAD (extra authenticate-only data) / masked 802.11 header
313 	 * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
314 	put_unaligned_be16(len_a, &aad[0]);
315 	put_unaligned(mask_fc, (__le16 *)&aad[2]);
316 	memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
317 
318 	/* Mask Seq#, leave Frag# */
319 	aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
320 	aad[23] = 0;
321 
322 	if (a4_included) {
323 		memcpy(&aad[24], hdr->addr4, ETH_ALEN);
324 		aad[30] = qos_tid;
325 		aad[31] = 0;
326 	} else {
327 		memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
328 		aad[24] = qos_tid;
329 	}
330 }
331 
332 
333 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
334 {
335 	hdr[0] = pn[5];
336 	hdr[1] = pn[4];
337 	hdr[2] = 0;
338 	hdr[3] = 0x20 | (key_id << 6);
339 	hdr[4] = pn[3];
340 	hdr[5] = pn[2];
341 	hdr[6] = pn[1];
342 	hdr[7] = pn[0];
343 }
344 
345 
346 static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr)
347 {
348 	pn[0] = hdr[7];
349 	pn[1] = hdr[6];
350 	pn[2] = hdr[5];
351 	pn[3] = hdr[4];
352 	pn[4] = hdr[1];
353 	pn[5] = hdr[0];
354 }
355 
356 
357 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
358 {
359 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
360 	struct ieee80211_key *key = tx->key;
361 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
362 	int hdrlen, len, tail;
363 	u8 *pos, *pn;
364 	int i;
365 	bool skip_hw;
366 
367 	skip_hw = (tx->key->conf.flags & IEEE80211_KEY_FLAG_SW_MGMT) &&
368 		ieee80211_is_mgmt(hdr->frame_control);
369 
370 	if ((tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) &&
371 	    !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
372 	    !skip_hw) {
373 		/* hwaccel - with no need for preallocated room for CCMP
374 		 * header or MIC fields */
375 		info->control.hw_key = &tx->key->conf;
376 		return 0;
377 	}
378 
379 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
380 	len = skb->len - hdrlen;
381 
382 	if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
383 		tail = 0;
384 	else
385 		tail = CCMP_MIC_LEN;
386 
387 	if (WARN_ON(skb_tailroom(skb) < tail ||
388 		    skb_headroom(skb) < CCMP_HDR_LEN))
389 		return -1;
390 
391 	pos = skb_push(skb, CCMP_HDR_LEN);
392 	memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
393 	hdr = (struct ieee80211_hdr *) pos;
394 	pos += hdrlen;
395 
396 	/* PN = PN + 1 */
397 	pn = key->u.ccmp.tx_pn;
398 
399 	for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
400 		pn[i]++;
401 		if (pn[i])
402 			break;
403 	}
404 
405 	ccmp_pn2hdr(pos, pn, key->conf.keyidx);
406 
407 	if ((key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) && !skip_hw) {
408 		/* hwaccel - with preallocated room for CCMP header */
409 		info->control.hw_key = &tx->key->conf;
410 		return 0;
411 	}
412 
413 	pos += CCMP_HDR_LEN;
414 	ccmp_special_blocks(skb, pn, key->u.ccmp.tx_crypto_buf, 0);
415 	ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, key->u.ccmp.tx_crypto_buf, pos, len,
416 				  pos, skb_put(skb, CCMP_MIC_LEN));
417 
418 	return 0;
419 }
420 
421 
422 ieee80211_tx_result
423 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
424 {
425 	struct sk_buff *skb = tx->skb;
426 
427 	ieee80211_tx_set_protected(tx);
428 
429 	do {
430 		if (ccmp_encrypt_skb(tx, skb) < 0)
431 			return TX_DROP;
432 	} while ((skb = skb->next));
433 
434 	return TX_CONTINUE;
435 }
436 
437 
438 ieee80211_rx_result
439 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
440 {
441 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
442 	int hdrlen;
443 	struct ieee80211_key *key = rx->key;
444 	struct sk_buff *skb = rx->skb;
445 	u8 pn[CCMP_PN_LEN];
446 	int data_len;
447 
448 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
449 
450 	if (!ieee80211_is_data(hdr->frame_control) &&
451 	    !ieee80211_is_robust_mgmt_frame(hdr))
452 		return RX_CONTINUE;
453 
454 	data_len = skb->len - hdrlen - CCMP_HDR_LEN - CCMP_MIC_LEN;
455 	if (!rx->sta || data_len < 0)
456 		return RX_DROP_UNUSABLE;
457 
458 	if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
459 	    (rx->status->flag & RX_FLAG_IV_STRIPPED))
460 		return RX_CONTINUE;
461 
462 	ccmp_hdr2pn(pn, skb->data + hdrlen);
463 
464 	if (memcmp(pn, key->u.ccmp.rx_pn[rx->queue], CCMP_PN_LEN) <= 0) {
465 		key->u.ccmp.replays++;
466 		return RX_DROP_UNUSABLE;
467 	}
468 
469 	if (!(rx->status->flag & RX_FLAG_DECRYPTED)) {
470 		/* hardware didn't decrypt/verify MIC */
471 		ccmp_special_blocks(skb, pn, key->u.ccmp.rx_crypto_buf, 1);
472 
473 		if (ieee80211_aes_ccm_decrypt(
474 			    key->u.ccmp.tfm, key->u.ccmp.rx_crypto_buf,
475 			    skb->data + hdrlen + CCMP_HDR_LEN, data_len,
476 			    skb->data + skb->len - CCMP_MIC_LEN,
477 			    skb->data + hdrlen + CCMP_HDR_LEN))
478 			return RX_DROP_UNUSABLE;
479 	}
480 
481 	memcpy(key->u.ccmp.rx_pn[rx->queue], pn, CCMP_PN_LEN);
482 
483 	/* Remove CCMP header and MIC */
484 	skb_trim(skb, skb->len - CCMP_MIC_LEN);
485 	memmove(skb->data + CCMP_HDR_LEN, skb->data, hdrlen);
486 	skb_pull(skb, CCMP_HDR_LEN);
487 
488 	return RX_CONTINUE;
489 }
490 
491 
492 static void bip_aad(struct sk_buff *skb, u8 *aad)
493 {
494 	/* BIP AAD: FC(masked) || A1 || A2 || A3 */
495 
496 	/* FC type/subtype */
497 	aad[0] = skb->data[0];
498 	/* Mask FC Retry, PwrMgt, MoreData flags to zero */
499 	aad[1] = skb->data[1] & ~(BIT(4) | BIT(5) | BIT(6));
500 	/* A1 || A2 || A3 */
501 	memcpy(aad + 2, skb->data + 4, 3 * ETH_ALEN);
502 }
503 
504 
505 static inline void bip_ipn_swap(u8 *d, const u8 *s)
506 {
507 	*d++ = s[5];
508 	*d++ = s[4];
509 	*d++ = s[3];
510 	*d++ = s[2];
511 	*d++ = s[1];
512 	*d = s[0];
513 }
514 
515 
516 ieee80211_tx_result
517 ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
518 {
519 	struct sk_buff *skb = tx->skb;
520 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
521 	struct ieee80211_key *key = tx->key;
522 	struct ieee80211_mmie *mmie;
523 	u8 *pn, aad[20];
524 	int i;
525 
526 	if (tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
527 		/* hwaccel */
528 		info->control.hw_key = &tx->key->conf;
529 		return 0;
530 	}
531 
532 	if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie)))
533 		return TX_DROP;
534 
535 	mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie));
536 	mmie->element_id = WLAN_EID_MMIE;
537 	mmie->length = sizeof(*mmie) - 2;
538 	mmie->key_id = cpu_to_le16(key->conf.keyidx);
539 
540 	/* PN = PN + 1 */
541 	pn = key->u.aes_cmac.tx_pn;
542 
543 	for (i = sizeof(key->u.aes_cmac.tx_pn) - 1; i >= 0; i--) {
544 		pn[i]++;
545 		if (pn[i])
546 			break;
547 	}
548 	bip_ipn_swap(mmie->sequence_number, pn);
549 
550 	bip_aad(skb, aad);
551 
552 	/*
553 	 * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64)
554 	 */
555 	ieee80211_aes_cmac(key->u.aes_cmac.tfm, key->u.aes_cmac.tx_crypto_buf,
556 			   aad, skb->data + 24, skb->len - 24, mmie->mic);
557 
558 	return TX_CONTINUE;
559 }
560 
561 
562 ieee80211_rx_result
563 ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
564 {
565 	struct sk_buff *skb = rx->skb;
566 	struct ieee80211_key *key = rx->key;
567 	struct ieee80211_mmie *mmie;
568 	u8 aad[20], mic[8], ipn[6];
569 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
570 
571 	if (!ieee80211_is_mgmt(hdr->frame_control))
572 		return RX_CONTINUE;
573 
574 	if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
575 	    (rx->status->flag & RX_FLAG_IV_STRIPPED))
576 		return RX_CONTINUE;
577 
578 	if (skb->len < 24 + sizeof(*mmie))
579 		return RX_DROP_UNUSABLE;
580 
581 	mmie = (struct ieee80211_mmie *)
582 		(skb->data + skb->len - sizeof(*mmie));
583 	if (mmie->element_id != WLAN_EID_MMIE ||
584 	    mmie->length != sizeof(*mmie) - 2)
585 		return RX_DROP_UNUSABLE; /* Invalid MMIE */
586 
587 	bip_ipn_swap(ipn, mmie->sequence_number);
588 
589 	if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) {
590 		key->u.aes_cmac.replays++;
591 		return RX_DROP_UNUSABLE;
592 	}
593 
594 	if (!(rx->status->flag & RX_FLAG_DECRYPTED)) {
595 		/* hardware didn't decrypt/verify MIC */
596 		bip_aad(skb, aad);
597 		ieee80211_aes_cmac(key->u.aes_cmac.tfm,
598 				   key->u.aes_cmac.rx_crypto_buf, aad,
599 				   skb->data + 24, skb->len - 24, mic);
600 		if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
601 			key->u.aes_cmac.icverrors++;
602 			return RX_DROP_UNUSABLE;
603 		}
604 	}
605 
606 	memcpy(key->u.aes_cmac.rx_pn, ipn, 6);
607 
608 	/* Remove MMIE */
609 	skb_trim(skb, skb->len - sizeof(*mmie));
610 
611 	return RX_CONTINUE;
612 }
613