xref: /openbmc/linux/net/mac80211/wpa.c (revision 3c6a73cc)
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 += IEEE80211_TKIP_ICV_LEN;
66 
67 	if (WARN(skb_tailroom(skb) < tail ||
68 		 skb_headroom(skb) < IEEE80211_TKIP_IV_LEN,
69 		 "mmic: not enough head/tail (%d/%d,%d/%d)\n",
70 		 skb_headroom(skb), IEEE80211_TKIP_IV_LEN,
71 		 skb_tailroom(skb), tail))
72 		return TX_DROP;
73 
74 	key = &tx->key->conf.key[NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY];
75 	mic = skb_put(skb, MICHAEL_MIC_LEN);
76 	michael_mic(key, hdr, data, data_len, mic);
77 	if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE))
78 		mic[0]++;
79 
80 	return TX_CONTINUE;
81 }
82 
83 
84 ieee80211_rx_result
85 ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
86 {
87 	u8 *data, *key = NULL;
88 	size_t data_len;
89 	unsigned int hdrlen;
90 	u8 mic[MICHAEL_MIC_LEN];
91 	struct sk_buff *skb = rx->skb;
92 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
93 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
94 
95 	/*
96 	 * it makes no sense to check for MIC errors on anything other
97 	 * than data frames.
98 	 */
99 	if (!ieee80211_is_data_present(hdr->frame_control))
100 		return RX_CONTINUE;
101 
102 	/*
103 	 * No way to verify the MIC if the hardware stripped it or
104 	 * the IV with the key index. In this case we have solely rely
105 	 * on the driver to set RX_FLAG_MMIC_ERROR in the event of a
106 	 * MIC failure report.
107 	 */
108 	if (status->flag & (RX_FLAG_MMIC_STRIPPED | RX_FLAG_IV_STRIPPED)) {
109 		if (status->flag & RX_FLAG_MMIC_ERROR)
110 			goto mic_fail_no_key;
111 
112 		if (!(status->flag & RX_FLAG_IV_STRIPPED) && rx->key &&
113 		    rx->key->conf.cipher == WLAN_CIPHER_SUITE_TKIP)
114 			goto update_iv;
115 
116 		return RX_CONTINUE;
117 	}
118 
119 	/*
120 	 * Some hardware seems to generate Michael MIC failure reports; even
121 	 * though, the frame was not encrypted with TKIP and therefore has no
122 	 * MIC. Ignore the flag them to avoid triggering countermeasures.
123 	 */
124 	if (!rx->key || rx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP ||
125 	    !(status->flag & RX_FLAG_DECRYPTED))
126 		return RX_CONTINUE;
127 
128 	if (rx->sdata->vif.type == NL80211_IFTYPE_AP && rx->key->conf.keyidx) {
129 		/*
130 		 * APs with pairwise keys should never receive Michael MIC
131 		 * errors for non-zero keyidx because these are reserved for
132 		 * group keys and only the AP is sending real multicast
133 		 * frames in the BSS.
134 		 */
135 		return RX_DROP_UNUSABLE;
136 	}
137 
138 	if (status->flag & RX_FLAG_MMIC_ERROR)
139 		goto mic_fail;
140 
141 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
142 	if (skb->len < hdrlen + MICHAEL_MIC_LEN)
143 		return RX_DROP_UNUSABLE;
144 
145 	if (skb_linearize(rx->skb))
146 		return RX_DROP_UNUSABLE;
147 	hdr = (void *)skb->data;
148 
149 	data = skb->data + hdrlen;
150 	data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
151 	key = &rx->key->conf.key[NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY];
152 	michael_mic(key, hdr, data, data_len, mic);
153 	if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0)
154 		goto mic_fail;
155 
156 	/* remove Michael MIC from payload */
157 	skb_trim(skb, skb->len - MICHAEL_MIC_LEN);
158 
159 update_iv:
160 	/* update IV in key information to be able to detect replays */
161 	rx->key->u.tkip.rx[rx->security_idx].iv32 = rx->tkip_iv32;
162 	rx->key->u.tkip.rx[rx->security_idx].iv16 = rx->tkip_iv16;
163 
164 	return RX_CONTINUE;
165 
166 mic_fail:
167 	rx->key->u.tkip.mic_failures++;
168 
169 mic_fail_no_key:
170 	/*
171 	 * In some cases the key can be unset - e.g. a multicast packet, in
172 	 * a driver that supports HW encryption. Send up the key idx only if
173 	 * the key is set.
174 	 */
175 	mac80211_ev_michael_mic_failure(rx->sdata,
176 					rx->key ? rx->key->conf.keyidx : -1,
177 					(void *) skb->data, NULL, GFP_ATOMIC);
178 	return RX_DROP_UNUSABLE;
179 }
180 
181 
182 static int tkip_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
183 {
184 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
185 	struct ieee80211_key *key = tx->key;
186 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
187 	unsigned int hdrlen;
188 	int len, tail;
189 	u8 *pos;
190 
191 	if (info->control.hw_key &&
192 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
193 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
194 		/* hwaccel - with no need for software-generated IV */
195 		return 0;
196 	}
197 
198 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
199 	len = skb->len - hdrlen;
200 
201 	if (info->control.hw_key)
202 		tail = 0;
203 	else
204 		tail = IEEE80211_TKIP_ICV_LEN;
205 
206 	if (WARN_ON(skb_tailroom(skb) < tail ||
207 		    skb_headroom(skb) < IEEE80211_TKIP_IV_LEN))
208 		return -1;
209 
210 	pos = skb_push(skb, IEEE80211_TKIP_IV_LEN);
211 	memmove(pos, pos + IEEE80211_TKIP_IV_LEN, hdrlen);
212 	skb_set_network_header(skb, skb_network_offset(skb) +
213 				    IEEE80211_TKIP_IV_LEN);
214 	pos += hdrlen;
215 
216 	/* the HW only needs room for the IV, but not the actual IV */
217 	if (info->control.hw_key &&
218 	    (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
219 		return 0;
220 
221 	/* Increase IV for the frame */
222 	spin_lock(&key->u.tkip.txlock);
223 	key->u.tkip.tx.iv16++;
224 	if (key->u.tkip.tx.iv16 == 0)
225 		key->u.tkip.tx.iv32++;
226 	pos = ieee80211_tkip_add_iv(pos, key);
227 	spin_unlock(&key->u.tkip.txlock);
228 
229 	/* hwaccel - with software IV */
230 	if (info->control.hw_key)
231 		return 0;
232 
233 	/* Add room for ICV */
234 	skb_put(skb, IEEE80211_TKIP_ICV_LEN);
235 
236 	return ieee80211_tkip_encrypt_data(tx->local->wep_tx_tfm,
237 					   key, skb, pos, len);
238 }
239 
240 
241 ieee80211_tx_result
242 ieee80211_crypto_tkip_encrypt(struct ieee80211_tx_data *tx)
243 {
244 	struct sk_buff *skb;
245 
246 	ieee80211_tx_set_protected(tx);
247 
248 	skb_queue_walk(&tx->skbs, skb) {
249 		if (tkip_encrypt_skb(tx, skb) < 0)
250 			return TX_DROP;
251 	}
252 
253 	return TX_CONTINUE;
254 }
255 
256 
257 ieee80211_rx_result
258 ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
259 {
260 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
261 	int hdrlen, res, hwaccel = 0;
262 	struct ieee80211_key *key = rx->key;
263 	struct sk_buff *skb = rx->skb;
264 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
265 
266 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
267 
268 	if (!ieee80211_is_data(hdr->frame_control))
269 		return RX_CONTINUE;
270 
271 	if (!rx->sta || skb->len - hdrlen < 12)
272 		return RX_DROP_UNUSABLE;
273 
274 	/* it may be possible to optimize this a bit more */
275 	if (skb_linearize(rx->skb))
276 		return RX_DROP_UNUSABLE;
277 	hdr = (void *)skb->data;
278 
279 	/*
280 	 * Let TKIP code verify IV, but skip decryption.
281 	 * In the case where hardware checks the IV as well,
282 	 * we don't even get here, see ieee80211_rx_h_decrypt()
283 	 */
284 	if (status->flag & RX_FLAG_DECRYPTED)
285 		hwaccel = 1;
286 
287 	res = ieee80211_tkip_decrypt_data(rx->local->wep_rx_tfm,
288 					  key, skb->data + hdrlen,
289 					  skb->len - hdrlen, rx->sta->sta.addr,
290 					  hdr->addr1, hwaccel, rx->security_idx,
291 					  &rx->tkip_iv32,
292 					  &rx->tkip_iv16);
293 	if (res != TKIP_DECRYPT_OK)
294 		return RX_DROP_UNUSABLE;
295 
296 	/* Trim ICV */
297 	skb_trim(skb, skb->len - IEEE80211_TKIP_ICV_LEN);
298 
299 	/* Remove IV */
300 	memmove(skb->data + IEEE80211_TKIP_IV_LEN, skb->data, hdrlen);
301 	skb_pull(skb, IEEE80211_TKIP_IV_LEN);
302 
303 	return RX_CONTINUE;
304 }
305 
306 
307 static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *b_0, u8 *aad)
308 {
309 	__le16 mask_fc;
310 	int a4_included, mgmt;
311 	u8 qos_tid;
312 	u16 len_a;
313 	unsigned int hdrlen;
314 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
315 
316 	/*
317 	 * Mask FC: zero subtype b4 b5 b6 (if not mgmt)
318 	 * Retry, PwrMgt, MoreData; set Protected
319 	 */
320 	mgmt = ieee80211_is_mgmt(hdr->frame_control);
321 	mask_fc = hdr->frame_control;
322 	mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY |
323 				IEEE80211_FCTL_PM | IEEE80211_FCTL_MOREDATA);
324 	if (!mgmt)
325 		mask_fc &= ~cpu_to_le16(0x0070);
326 	mask_fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
327 
328 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
329 	len_a = hdrlen - 2;
330 	a4_included = ieee80211_has_a4(hdr->frame_control);
331 
332 	if (ieee80211_is_data_qos(hdr->frame_control))
333 		qos_tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
334 	else
335 		qos_tid = 0;
336 
337 	/* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC
338 	 * mode authentication are not allowed to collide, yet both are derived
339 	 * from this vector b_0. We only set L := 1 here to indicate that the
340 	 * data size can be represented in (L+1) bytes. The CCM layer will take
341 	 * care of storing the data length in the top (L+1) bytes and setting
342 	 * and clearing the other bits as is required to derive the two IVs.
343 	 */
344 	b_0[0] = 0x1;
345 
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, IEEE80211_CCMP_PN_LEN);
352 
353 	/* AAD (extra authenticate-only data) / masked 802.11 header
354 	 * FC | A1 | A2 | A3 | SC | [A4] | [QC] */
355 	put_unaligned_be16(len_a, &aad[0]);
356 	put_unaligned(mask_fc, (__le16 *)&aad[2]);
357 	memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);
358 
359 	/* Mask Seq#, leave Frag# */
360 	aad[22] = *((u8 *) &hdr->seq_ctrl) & 0x0f;
361 	aad[23] = 0;
362 
363 	if (a4_included) {
364 		memcpy(&aad[24], hdr->addr4, ETH_ALEN);
365 		aad[30] = qos_tid;
366 		aad[31] = 0;
367 	} else {
368 		memset(&aad[24], 0, ETH_ALEN + IEEE80211_QOS_CTL_LEN);
369 		aad[24] = qos_tid;
370 	}
371 }
372 
373 
374 static inline void ccmp_pn2hdr(u8 *hdr, u8 *pn, int key_id)
375 {
376 	hdr[0] = pn[5];
377 	hdr[1] = pn[4];
378 	hdr[2] = 0;
379 	hdr[3] = 0x20 | (key_id << 6);
380 	hdr[4] = pn[3];
381 	hdr[5] = pn[2];
382 	hdr[6] = pn[1];
383 	hdr[7] = pn[0];
384 }
385 
386 
387 static inline void ccmp_hdr2pn(u8 *pn, u8 *hdr)
388 {
389 	pn[0] = hdr[7];
390 	pn[1] = hdr[6];
391 	pn[2] = hdr[5];
392 	pn[3] = hdr[4];
393 	pn[4] = hdr[1];
394 	pn[5] = hdr[0];
395 }
396 
397 
398 static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
399 {
400 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
401 	struct ieee80211_key *key = tx->key;
402 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
403 	int hdrlen, len, tail;
404 	u8 *pos;
405 	u8 pn[6];
406 	u64 pn64;
407 	u8 aad[2 * AES_BLOCK_SIZE];
408 	u8 b_0[AES_BLOCK_SIZE];
409 
410 	if (info->control.hw_key &&
411 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
412 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE) &&
413 	    !((info->control.hw_key->flags &
414 	       IEEE80211_KEY_FLAG_GENERATE_IV_MGMT) &&
415 	      ieee80211_is_mgmt(hdr->frame_control))) {
416 		/*
417 		 * hwaccel has no need for preallocated room for CCMP
418 		 * header or MIC fields
419 		 */
420 		return 0;
421 	}
422 
423 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
424 	len = skb->len - hdrlen;
425 
426 	if (info->control.hw_key)
427 		tail = 0;
428 	else
429 		tail = IEEE80211_CCMP_MIC_LEN;
430 
431 	if (WARN_ON(skb_tailroom(skb) < tail ||
432 		    skb_headroom(skb) < IEEE80211_CCMP_HDR_LEN))
433 		return -1;
434 
435 	pos = skb_push(skb, IEEE80211_CCMP_HDR_LEN);
436 	memmove(pos, pos + IEEE80211_CCMP_HDR_LEN, hdrlen);
437 	skb_set_network_header(skb, skb_network_offset(skb) +
438 				    IEEE80211_CCMP_HDR_LEN);
439 
440 	/* the HW only needs room for the IV, but not the actual IV */
441 	if (info->control.hw_key &&
442 	    (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
443 		return 0;
444 
445 	hdr = (struct ieee80211_hdr *) pos;
446 	pos += hdrlen;
447 
448 	pn64 = atomic64_inc_return(&key->u.ccmp.tx_pn);
449 
450 	pn[5] = pn64;
451 	pn[4] = pn64 >> 8;
452 	pn[3] = pn64 >> 16;
453 	pn[2] = pn64 >> 24;
454 	pn[1] = pn64 >> 32;
455 	pn[0] = pn64 >> 40;
456 
457 	ccmp_pn2hdr(pos, pn, key->conf.keyidx);
458 
459 	/* hwaccel - with software CCMP header */
460 	if (info->control.hw_key)
461 		return 0;
462 
463 	pos += IEEE80211_CCMP_HDR_LEN;
464 	ccmp_special_blocks(skb, pn, b_0, aad);
465 	ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, b_0, aad, pos, len,
466 				  skb_put(skb, IEEE80211_CCMP_MIC_LEN));
467 
468 	return 0;
469 }
470 
471 
472 ieee80211_tx_result
473 ieee80211_crypto_ccmp_encrypt(struct ieee80211_tx_data *tx)
474 {
475 	struct sk_buff *skb;
476 
477 	ieee80211_tx_set_protected(tx);
478 
479 	skb_queue_walk(&tx->skbs, skb) {
480 		if (ccmp_encrypt_skb(tx, skb) < 0)
481 			return TX_DROP;
482 	}
483 
484 	return TX_CONTINUE;
485 }
486 
487 
488 ieee80211_rx_result
489 ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
490 {
491 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
492 	int hdrlen;
493 	struct ieee80211_key *key = rx->key;
494 	struct sk_buff *skb = rx->skb;
495 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
496 	u8 pn[IEEE80211_CCMP_PN_LEN];
497 	int data_len;
498 	int queue;
499 
500 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
501 
502 	if (!ieee80211_is_data(hdr->frame_control) &&
503 	    !ieee80211_is_robust_mgmt_frame(skb))
504 		return RX_CONTINUE;
505 
506 	data_len = skb->len - hdrlen - IEEE80211_CCMP_HDR_LEN -
507 		   IEEE80211_CCMP_MIC_LEN;
508 	if (!rx->sta || data_len < 0)
509 		return RX_DROP_UNUSABLE;
510 
511 	if (status->flag & RX_FLAG_DECRYPTED) {
512 		if (!pskb_may_pull(rx->skb, hdrlen + IEEE80211_CCMP_HDR_LEN))
513 			return RX_DROP_UNUSABLE;
514 	} else {
515 		if (skb_linearize(rx->skb))
516 			return RX_DROP_UNUSABLE;
517 	}
518 
519 	ccmp_hdr2pn(pn, skb->data + hdrlen);
520 
521 	queue = rx->security_idx;
522 
523 	if (memcmp(pn, key->u.ccmp.rx_pn[queue], IEEE80211_CCMP_PN_LEN) <= 0) {
524 		key->u.ccmp.replays++;
525 		return RX_DROP_UNUSABLE;
526 	}
527 
528 	if (!(status->flag & RX_FLAG_DECRYPTED)) {
529 		u8 aad[2 * AES_BLOCK_SIZE];
530 		u8 b_0[AES_BLOCK_SIZE];
531 		/* hardware didn't decrypt/verify MIC */
532 		ccmp_special_blocks(skb, pn, b_0, aad);
533 
534 		if (ieee80211_aes_ccm_decrypt(
535 			    key->u.ccmp.tfm, b_0, aad,
536 			    skb->data + hdrlen + IEEE80211_CCMP_HDR_LEN,
537 			    data_len,
538 			    skb->data + skb->len - IEEE80211_CCMP_MIC_LEN))
539 			return RX_DROP_UNUSABLE;
540 	}
541 
542 	memcpy(key->u.ccmp.rx_pn[queue], pn, IEEE80211_CCMP_PN_LEN);
543 
544 	/* Remove CCMP header and MIC */
545 	if (pskb_trim(skb, skb->len - IEEE80211_CCMP_MIC_LEN))
546 		return RX_DROP_UNUSABLE;
547 	memmove(skb->data + IEEE80211_CCMP_HDR_LEN, skb->data, hdrlen);
548 	skb_pull(skb, IEEE80211_CCMP_HDR_LEN);
549 
550 	return RX_CONTINUE;
551 }
552 
553 static ieee80211_tx_result
554 ieee80211_crypto_cs_encrypt(struct ieee80211_tx_data *tx,
555 			    struct sk_buff *skb)
556 {
557 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
558 	struct ieee80211_key *key = tx->key;
559 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
560 	const struct ieee80211_cipher_scheme *cs = key->sta->cipher_scheme;
561 	int hdrlen;
562 	u8 *pos;
563 
564 	if (info->control.hw_key &&
565 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
566 		/* hwaccel has no need for preallocated head room */
567 		return TX_CONTINUE;
568 	}
569 
570 	if (unlikely(skb_headroom(skb) < cs->hdr_len &&
571 		     pskb_expand_head(skb, cs->hdr_len, 0, GFP_ATOMIC)))
572 		return TX_DROP;
573 
574 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
575 
576 	pos = skb_push(skb, cs->hdr_len);
577 	memmove(pos, pos + cs->hdr_len, hdrlen);
578 	skb_set_network_header(skb, skb_network_offset(skb) + cs->hdr_len);
579 
580 	return TX_CONTINUE;
581 }
582 
583 static inline int ieee80211_crypto_cs_pn_compare(u8 *pn1, u8 *pn2, int len)
584 {
585 	int i;
586 
587 	/* pn is little endian */
588 	for (i = len - 1; i >= 0; i--) {
589 		if (pn1[i] < pn2[i])
590 			return -1;
591 		else if (pn1[i] > pn2[i])
592 			return 1;
593 	}
594 
595 	return 0;
596 }
597 
598 static ieee80211_rx_result
599 ieee80211_crypto_cs_decrypt(struct ieee80211_rx_data *rx)
600 {
601 	struct ieee80211_key *key = rx->key;
602 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
603 	const struct ieee80211_cipher_scheme *cs = NULL;
604 	int hdrlen = ieee80211_hdrlen(hdr->frame_control);
605 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
606 	int data_len;
607 	u8 *rx_pn;
608 	u8 *skb_pn;
609 	u8 qos_tid;
610 
611 	if (!rx->sta || !rx->sta->cipher_scheme ||
612 	    !(status->flag & RX_FLAG_DECRYPTED))
613 		return RX_DROP_UNUSABLE;
614 
615 	if (!ieee80211_is_data(hdr->frame_control))
616 		return RX_CONTINUE;
617 
618 	cs = rx->sta->cipher_scheme;
619 
620 	data_len = rx->skb->len - hdrlen - cs->hdr_len;
621 
622 	if (data_len < 0)
623 		return RX_DROP_UNUSABLE;
624 
625 	if (ieee80211_is_data_qos(hdr->frame_control))
626 		qos_tid = *ieee80211_get_qos_ctl(hdr) &
627 				IEEE80211_QOS_CTL_TID_MASK;
628 	else
629 		qos_tid = 0;
630 
631 	if (skb_linearize(rx->skb))
632 		return RX_DROP_UNUSABLE;
633 
634 	hdr = (struct ieee80211_hdr *)rx->skb->data;
635 
636 	rx_pn = key->u.gen.rx_pn[qos_tid];
637 	skb_pn = rx->skb->data + hdrlen + cs->pn_off;
638 
639 	if (ieee80211_crypto_cs_pn_compare(skb_pn, rx_pn, cs->pn_len) <= 0)
640 		return RX_DROP_UNUSABLE;
641 
642 	memcpy(rx_pn, skb_pn, cs->pn_len);
643 
644 	/* remove security header and MIC */
645 	if (pskb_trim(rx->skb, rx->skb->len - cs->mic_len))
646 		return RX_DROP_UNUSABLE;
647 
648 	memmove(rx->skb->data + cs->hdr_len, rx->skb->data, hdrlen);
649 	skb_pull(rx->skb, cs->hdr_len);
650 
651 	return RX_CONTINUE;
652 }
653 
654 static void bip_aad(struct sk_buff *skb, u8 *aad)
655 {
656 	__le16 mask_fc;
657 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
658 
659 	/* BIP AAD: FC(masked) || A1 || A2 || A3 */
660 
661 	/* FC type/subtype */
662 	/* Mask FC Retry, PwrMgt, MoreData flags to zero */
663 	mask_fc = hdr->frame_control;
664 	mask_fc &= ~cpu_to_le16(IEEE80211_FCTL_RETRY | IEEE80211_FCTL_PM |
665 				IEEE80211_FCTL_MOREDATA);
666 	put_unaligned(mask_fc, (__le16 *) &aad[0]);
667 	/* A1 || A2 || A3 */
668 	memcpy(aad + 2, &hdr->addr1, 3 * ETH_ALEN);
669 }
670 
671 
672 static inline void bip_ipn_set64(u8 *d, u64 pn)
673 {
674 	*d++ = pn;
675 	*d++ = pn >> 8;
676 	*d++ = pn >> 16;
677 	*d++ = pn >> 24;
678 	*d++ = pn >> 32;
679 	*d = pn >> 40;
680 }
681 
682 static inline void bip_ipn_swap(u8 *d, const u8 *s)
683 {
684 	*d++ = s[5];
685 	*d++ = s[4];
686 	*d++ = s[3];
687 	*d++ = s[2];
688 	*d++ = s[1];
689 	*d = s[0];
690 }
691 
692 
693 ieee80211_tx_result
694 ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
695 {
696 	struct sk_buff *skb;
697 	struct ieee80211_tx_info *info;
698 	struct ieee80211_key *key = tx->key;
699 	struct ieee80211_mmie *mmie;
700 	u8 aad[20];
701 	u64 pn64;
702 
703 	if (WARN_ON(skb_queue_len(&tx->skbs) != 1))
704 		return TX_DROP;
705 
706 	skb = skb_peek(&tx->skbs);
707 
708 	info = IEEE80211_SKB_CB(skb);
709 
710 	if (info->control.hw_key)
711 		return TX_CONTINUE;
712 
713 	if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie)))
714 		return TX_DROP;
715 
716 	mmie = (struct ieee80211_mmie *) skb_put(skb, sizeof(*mmie));
717 	mmie->element_id = WLAN_EID_MMIE;
718 	mmie->length = sizeof(*mmie) - 2;
719 	mmie->key_id = cpu_to_le16(key->conf.keyidx);
720 
721 	/* PN = PN + 1 */
722 	pn64 = atomic64_inc_return(&key->u.aes_cmac.tx_pn);
723 
724 	bip_ipn_set64(mmie->sequence_number, pn64);
725 
726 	bip_aad(skb, aad);
727 
728 	/*
729 	 * MIC = AES-128-CMAC(IGTK, AAD || Management Frame Body || MMIE, 64)
730 	 */
731 	ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
732 			   skb->data + 24, skb->len - 24, mmie->mic);
733 
734 	return TX_CONTINUE;
735 }
736 
737 
738 ieee80211_rx_result
739 ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx)
740 {
741 	struct sk_buff *skb = rx->skb;
742 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
743 	struct ieee80211_key *key = rx->key;
744 	struct ieee80211_mmie *mmie;
745 	u8 aad[20], mic[8], ipn[6];
746 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
747 
748 	if (!ieee80211_is_mgmt(hdr->frame_control))
749 		return RX_CONTINUE;
750 
751 	/* management frames are already linear */
752 
753 	if (skb->len < 24 + sizeof(*mmie))
754 		return RX_DROP_UNUSABLE;
755 
756 	mmie = (struct ieee80211_mmie *)
757 		(skb->data + skb->len - sizeof(*mmie));
758 	if (mmie->element_id != WLAN_EID_MMIE ||
759 	    mmie->length != sizeof(*mmie) - 2)
760 		return RX_DROP_UNUSABLE; /* Invalid MMIE */
761 
762 	bip_ipn_swap(ipn, mmie->sequence_number);
763 
764 	if (memcmp(ipn, key->u.aes_cmac.rx_pn, 6) <= 0) {
765 		key->u.aes_cmac.replays++;
766 		return RX_DROP_UNUSABLE;
767 	}
768 
769 	if (!(status->flag & RX_FLAG_DECRYPTED)) {
770 		/* hardware didn't decrypt/verify MIC */
771 		bip_aad(skb, aad);
772 		ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
773 				   skb->data + 24, skb->len - 24, mic);
774 		if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
775 			key->u.aes_cmac.icverrors++;
776 			return RX_DROP_UNUSABLE;
777 		}
778 	}
779 
780 	memcpy(key->u.aes_cmac.rx_pn, ipn, 6);
781 
782 	/* Remove MMIE */
783 	skb_trim(skb, skb->len - sizeof(*mmie));
784 
785 	return RX_CONTINUE;
786 }
787 
788 ieee80211_tx_result
789 ieee80211_crypto_hw_encrypt(struct ieee80211_tx_data *tx)
790 {
791 	struct sk_buff *skb;
792 	struct ieee80211_tx_info *info = NULL;
793 	ieee80211_tx_result res;
794 
795 	skb_queue_walk(&tx->skbs, skb) {
796 		info  = IEEE80211_SKB_CB(skb);
797 
798 		/* handle hw-only algorithm */
799 		if (!info->control.hw_key)
800 			return TX_DROP;
801 
802 		if (tx->key->sta->cipher_scheme) {
803 			res = ieee80211_crypto_cs_encrypt(tx, skb);
804 			if (res != TX_CONTINUE)
805 				return res;
806 		}
807 	}
808 
809 	ieee80211_tx_set_protected(tx);
810 
811 	return TX_CONTINUE;
812 }
813 
814 ieee80211_rx_result
815 ieee80211_crypto_hw_decrypt(struct ieee80211_rx_data *rx)
816 {
817 	if (rx->sta && rx->sta->cipher_scheme)
818 		return ieee80211_crypto_cs_decrypt(rx);
819 
820 	return RX_DROP_UNUSABLE;
821 }
822