1 /*-
2  * Copyright (c) 2002-2008 Sam Leffler, Errno Consulting
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  */
25 
26 #include <sys/cdefs.h>
27 __FBSDID("$FreeBSD$");
28 
29 /*
30  * IEEE 802.11i AES-CCMP crypto support.
31  *
32  * Part of this module is derived from similar code in the Host
33  * AP driver. The code is used with the consent of the author and
34  * it's license is included below.
35  */
36 #include "opt_wlan.h"
37 
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/mbuf.h>
41 #include <sys/malloc.h>
42 #include <sys/kernel.h>
43 #include <sys/module.h>
44 
45 #include <sys/socket.h>
46 
47 #include <net/if.h>
48 #include <net/if_media.h>
49 #include <net/ethernet.h>
50 
51 #include <netproto/802_11/ieee80211_var.h>
52 
53 #include <crypto/rijndael/rijndael.h>
54 
55 #define AES_BLOCK_LEN 16
56 
57 struct ccmp_ctx {
58 	struct ieee80211vap *cc_vap;	/* for diagnostics+statistics */
59 	struct ieee80211com *cc_ic;
60 	rijndael_ctx	     cc_aes;
61 };
62 
63 static	void *ccmp_attach(struct ieee80211vap *, struct ieee80211_key *);
64 static	void ccmp_detach(struct ieee80211_key *);
65 static	int ccmp_setkey(struct ieee80211_key *);
66 static	void ccmp_setiv(struct ieee80211_key *, uint8_t *);
67 static	int ccmp_encap(struct ieee80211_key *, struct mbuf *);
68 static	int ccmp_decap(struct ieee80211_key *, struct mbuf *, int);
69 static	int ccmp_enmic(struct ieee80211_key *, struct mbuf *, int);
70 static	int ccmp_demic(struct ieee80211_key *, struct mbuf *, int);
71 
72 static const struct ieee80211_cipher ccmp = {
73 	.ic_name	= "AES-CCM",
74 	.ic_cipher	= IEEE80211_CIPHER_AES_CCM,
75 	.ic_header	= IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN +
76 			  IEEE80211_WEP_EXTIVLEN,
77 	.ic_trailer	= IEEE80211_WEP_MICLEN,
78 	.ic_miclen	= 0,
79 	.ic_attach	= ccmp_attach,
80 	.ic_detach	= ccmp_detach,
81 	.ic_setkey	= ccmp_setkey,
82 	.ic_setiv	= ccmp_setiv,
83 	.ic_encap	= ccmp_encap,
84 	.ic_decap	= ccmp_decap,
85 	.ic_enmic	= ccmp_enmic,
86 	.ic_demic	= ccmp_demic,
87 };
88 
89 static	int ccmp_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
90 static	int ccmp_decrypt(struct ieee80211_key *, u_int64_t pn,
91 		struct mbuf *, int hdrlen);
92 
93 /* number of references from net80211 layer */
94 static	int nrefs = 0;
95 
96 static void *
97 ccmp_attach(struct ieee80211vap *vap, struct ieee80211_key *k)
98 {
99 	struct ccmp_ctx *ctx;
100 
101 #if defined(__DragonFly__)
102 	ctx = (struct ccmp_ctx *) kmalloc(sizeof(struct ccmp_ctx),
103 		M_80211_CRYPTO, M_INTWAIT | M_ZERO);
104 #else
105 	ctx = (struct ccmp_ctx *) IEEE80211_MALLOC(sizeof(struct ccmp_ctx),
106 		M_80211_CRYPTO, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
107 #endif
108 	if (ctx == NULL) {
109 		vap->iv_stats.is_crypto_nomem++;
110 		return NULL;
111 	}
112 	ctx->cc_vap = vap;
113 	ctx->cc_ic = vap->iv_ic;
114 	nrefs++;			/* NB: we assume caller locking */
115 	return ctx;
116 }
117 
118 static void
119 ccmp_detach(struct ieee80211_key *k)
120 {
121 	struct ccmp_ctx *ctx = k->wk_private;
122 
123 	IEEE80211_FREE(ctx, M_80211_CRYPTO);
124 	KASSERT(nrefs > 0, ("imbalanced attach/detach"));
125 	nrefs--;			/* NB: we assume caller locking */
126 }
127 
128 static int
129 ccmp_setkey(struct ieee80211_key *k)
130 {
131 	struct ccmp_ctx *ctx = k->wk_private;
132 
133 	if (k->wk_keylen != (128/NBBY)) {
134 		IEEE80211_DPRINTF(ctx->cc_vap, IEEE80211_MSG_CRYPTO,
135 			"%s: Invalid key length %u, expecting %u\n",
136 			__func__, k->wk_keylen, 128/NBBY);
137 		return 0;
138 	}
139 	if (k->wk_flags & IEEE80211_KEY_SWENCRYPT)
140 		rijndael_set_key(&ctx->cc_aes, k->wk_key, k->wk_keylen*NBBY);
141 	return 1;
142 }
143 
144 static void
145 ccmp_setiv(struct ieee80211_key *k, uint8_t *ivp)
146 {
147 	struct ccmp_ctx *ctx = k->wk_private;
148 	struct ieee80211vap *vap = ctx->cc_vap;
149 	uint8_t keyid;
150 
151 	keyid = ieee80211_crypto_get_keyid(vap, k) << 6;
152 
153 	k->wk_keytsc++;
154 	ivp[0] = k->wk_keytsc >> 0;		/* PN0 */
155 	ivp[1] = k->wk_keytsc >> 8;		/* PN1 */
156 	ivp[2] = 0;				/* Reserved */
157 	ivp[3] = keyid | IEEE80211_WEP_EXTIV;	/* KeyID | ExtID */
158 	ivp[4] = k->wk_keytsc >> 16;		/* PN2 */
159 	ivp[5] = k->wk_keytsc >> 24;		/* PN3 */
160 	ivp[6] = k->wk_keytsc >> 32;		/* PN4 */
161 	ivp[7] = k->wk_keytsc >> 40;		/* PN5 */
162 }
163 
164 /*
165  * Add privacy headers appropriate for the specified key.
166  */
167 static int
168 ccmp_encap(struct ieee80211_key *k, struct mbuf *m)
169 {
170 	struct ccmp_ctx *ctx = k->wk_private;
171 	struct ieee80211com *ic = ctx->cc_ic;
172 	uint8_t *ivp;
173 	int hdrlen;
174 
175 	hdrlen = ieee80211_hdrspace(ic, mtod(m, void *));
176 
177 	/*
178 	 * Copy down 802.11 header and add the IV, KeyID, and ExtIV.
179 	 */
180 	M_PREPEND(m, ccmp.ic_header, M_NOWAIT);
181 	if (m == NULL)
182 		return 0;
183 	ivp = mtod(m, uint8_t *);
184 	bcopy(ivp + ccmp.ic_header, ivp, hdrlen);
185 	ivp += hdrlen;
186 
187 	ccmp_setiv(k, ivp);
188 
189 	/*
190 	 * Finally, do software encrypt if needed.
191 	 */
192 	if ((k->wk_flags & IEEE80211_KEY_SWENCRYPT) &&
193 	    !ccmp_encrypt(k, m, hdrlen))
194 		return 0;
195 
196 	return 1;
197 }
198 
199 /*
200  * Add MIC to the frame as needed.
201  */
202 static int
203 ccmp_enmic(struct ieee80211_key *k, struct mbuf *m, int force)
204 {
205 
206 	return 1;
207 }
208 
209 static __inline uint64_t
210 READ_6(uint8_t b0, uint8_t b1, uint8_t b2, uint8_t b3, uint8_t b4, uint8_t b5)
211 {
212 	uint32_t iv32 = (b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24);
213 	uint16_t iv16 = (b4 << 0) | (b5 << 8);
214 	return (((uint64_t)iv16) << 32) | iv32;
215 }
216 
217 /*
218  * Validate and strip privacy headers (and trailer) for a
219  * received frame. The specified key should be correct but
220  * is also verified.
221  */
222 static int
223 ccmp_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen)
224 {
225 	struct ccmp_ctx *ctx = k->wk_private;
226 	struct ieee80211vap *vap = ctx->cc_vap;
227 	struct ieee80211_frame *wh;
228 	uint8_t *ivp, tid;
229 	uint64_t pn;
230 
231 	/*
232 	 * Header should have extended IV and sequence number;
233 	 * verify the former and validate the latter.
234 	 */
235 	wh = mtod(m, struct ieee80211_frame *);
236 	ivp = mtod(m, uint8_t *) + hdrlen;
237 	if ((ivp[IEEE80211_WEP_IVLEN] & IEEE80211_WEP_EXTIV) == 0) {
238 		/*
239 		 * No extended IV; discard frame.
240 		 */
241 		IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
242 			"%s", "missing ExtIV for AES-CCM cipher");
243 		vap->iv_stats.is_rx_ccmpformat++;
244 		return 0;
245 	}
246 	tid = ieee80211_gettid(wh);
247 	pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
248 	if (pn <= k->wk_keyrsc[tid] &&
249 	    (k->wk_flags & IEEE80211_KEY_NOREPLAY) == 0) {
250 		/*
251 		 * Replay violation.
252 		 */
253 		ieee80211_notify_replay_failure(vap, wh, k, pn, tid);
254 		vap->iv_stats.is_rx_ccmpreplay++;
255 		return 0;
256 	}
257 
258 	/*
259 	 * Check if the device handled the decrypt in hardware.
260 	 * If so we just strip the header; otherwise we need to
261 	 * handle the decrypt in software.  Note that for the
262 	 * latter we leave the header in place for use in the
263 	 * decryption work.
264 	 */
265 	if ((k->wk_flags & IEEE80211_KEY_SWDECRYPT) &&
266 	    !ccmp_decrypt(k, pn, m, hdrlen))
267 		return 0;
268 
269 	/*
270 	 * Copy up 802.11 header and strip crypto bits.
271 	 */
272 	bcopy(mtod(m, void *), mtod(m, uint8_t *) + ccmp.ic_header, hdrlen);
273 	m_adj(m, ccmp.ic_header);
274 	m_adj(m, -ccmp.ic_trailer);
275 
276 	/*
277 	 * Ok to update rsc now.
278 	 */
279 	k->wk_keyrsc[tid] = pn;
280 
281 	return 1;
282 }
283 
284 /*
285  * Verify and strip MIC from the frame.
286  */
287 static int
288 ccmp_demic(struct ieee80211_key *k, struct mbuf *m, int force)
289 {
290 	return 1;
291 }
292 
293 static __inline void
294 xor_block(uint8_t *b, const uint8_t *a, size_t len)
295 {
296 	int i;
297 	for (i = 0; i < len; i++)
298 		b[i] ^= a[i];
299 }
300 
301 /*
302  * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
303  *
304  * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
305  *
306  * This program is free software; you can redistribute it and/or modify
307  * it under the terms of the GNU General Public License version 2 as
308  * published by the Free Software Foundation. See README and COPYING for
309  * more details.
310  *
311  * Alternatively, this software may be distributed under the terms of BSD
312  * license.
313  */
314 
315 static void
316 ccmp_init_blocks(rijndael_ctx *ctx, struct ieee80211_frame *wh,
317 	u_int64_t pn, size_t dlen,
318 	uint8_t b0[AES_BLOCK_LEN], uint8_t aad[2 * AES_BLOCK_LEN],
319 	uint8_t auth[AES_BLOCK_LEN], uint8_t s0[AES_BLOCK_LEN])
320 {
321 #define	IS_QOS_DATA(wh)	IEEE80211_QOS_HAS_SEQ(wh)
322 
323 	/* CCM Initial Block:
324 	 * Flag (Include authentication header, M=3 (8-octet MIC),
325 	 *       L=1 (2-octet Dlen))
326 	 * Nonce: 0x00 | A2 | PN
327 	 * Dlen */
328 	b0[0] = 0x59;
329 	/* NB: b0[1] set below */
330 	IEEE80211_ADDR_COPY(b0 + 2, wh->i_addr2);
331 	b0[8] = pn >> 40;
332 	b0[9] = pn >> 32;
333 	b0[10] = pn >> 24;
334 	b0[11] = pn >> 16;
335 	b0[12] = pn >> 8;
336 	b0[13] = pn >> 0;
337 	b0[14] = (dlen >> 8) & 0xff;
338 	b0[15] = dlen & 0xff;
339 
340 	/* AAD:
341 	 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
342 	 * A1 | A2 | A3
343 	 * SC with bits 4..15 (seq#) masked to zero
344 	 * A4 (if present)
345 	 * QC (if present)
346 	 */
347 	aad[0] = 0;	/* AAD length >> 8 */
348 	/* NB: aad[1] set below */
349 	aad[2] = wh->i_fc[0] & 0x8f;	/* XXX magic #s */
350 	aad[3] = wh->i_fc[1] & 0xc7;	/* XXX magic #s */
351 	/* NB: we know 3 addresses are contiguous */
352 	memcpy(aad + 4, wh->i_addr1, 3 * IEEE80211_ADDR_LEN);
353 	aad[22] = wh->i_seq[0] & IEEE80211_SEQ_FRAG_MASK;
354 	aad[23] = 0; /* all bits masked */
355 	/*
356 	 * Construct variable-length portion of AAD based
357 	 * on whether this is a 4-address frame/QOS frame.
358 	 * We always zero-pad to 32 bytes before running it
359 	 * through the cipher.
360 	 *
361 	 * We also fill in the priority bits of the CCM
362 	 * initial block as we know whether or not we have
363 	 * a QOS frame.
364 	 */
365 	if (IEEE80211_IS_DSTODS(wh)) {
366 		IEEE80211_ADDR_COPY(aad + 24,
367 			((struct ieee80211_frame_addr4 *)wh)->i_addr4);
368 		if (IS_QOS_DATA(wh)) {
369 			struct ieee80211_qosframe_addr4 *qwh4 =
370 				(struct ieee80211_qosframe_addr4 *) wh;
371 			aad[30] = qwh4->i_qos[0] & 0x0f;/* just priority bits */
372 			aad[31] = 0;
373 			b0[1] = aad[30];
374 			aad[1] = 22 + IEEE80211_ADDR_LEN + 2;
375 		} else {
376 			*(uint16_t *)&aad[30] = 0;
377 			b0[1] = 0;
378 			aad[1] = 22 + IEEE80211_ADDR_LEN;
379 		}
380 	} else {
381 		if (IS_QOS_DATA(wh)) {
382 			struct ieee80211_qosframe *qwh =
383 				(struct ieee80211_qosframe*) wh;
384 			aad[24] = qwh->i_qos[0] & 0x0f;	/* just priority bits */
385 			aad[25] = 0;
386 			b0[1] = aad[24];
387 			aad[1] = 22 + 2;
388 		} else {
389 			*(uint16_t *)&aad[24] = 0;
390 			b0[1] = 0;
391 			aad[1] = 22;
392 		}
393 		*(uint16_t *)&aad[26] = 0;
394 		*(uint32_t *)&aad[28] = 0;
395 	}
396 
397 	/* Start with the first block and AAD */
398 	rijndael_encrypt(ctx, b0, auth);
399 	xor_block(auth, aad, AES_BLOCK_LEN);
400 	rijndael_encrypt(ctx, auth, auth);
401 	xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
402 	rijndael_encrypt(ctx, auth, auth);
403 	b0[0] &= 0x07;
404 	b0[14] = b0[15] = 0;
405 	rijndael_encrypt(ctx, b0, s0);
406 #undef	IS_QOS_DATA
407 }
408 
409 #define	CCMP_ENCRYPT(_i, _b, _b0, _pos, _e, _len) do {	\
410 	/* Authentication */				\
411 	xor_block(_b, _pos, _len);			\
412 	rijndael_encrypt(&ctx->cc_aes, _b, _b);		\
413 	/* Encryption, with counter */			\
414 	_b0[14] = (_i >> 8) & 0xff;			\
415 	_b0[15] = _i & 0xff;				\
416 	rijndael_encrypt(&ctx->cc_aes, _b0, _e);	\
417 	xor_block(_pos, _e, _len);			\
418 } while (0)
419 
420 static int
421 ccmp_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
422 {
423 	struct ccmp_ctx *ctx = key->wk_private;
424 	struct ieee80211_frame *wh;
425 	struct mbuf *m = m0;
426 	int data_len, i, space;
427 	uint8_t aad[2 * AES_BLOCK_LEN], b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN],
428 		e[AES_BLOCK_LEN], s0[AES_BLOCK_LEN];
429 	uint8_t *pos;
430 
431 	ctx->cc_vap->iv_stats.is_crypto_ccmp++;
432 
433 	wh = mtod(m, struct ieee80211_frame *);
434 	data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header);
435 	ccmp_init_blocks(&ctx->cc_aes, wh, key->wk_keytsc,
436 		data_len, b0, aad, b, s0);
437 
438 	i = 1;
439 	pos = mtod(m, uint8_t *) + hdrlen + ccmp.ic_header;
440 	/* NB: assumes header is entirely in first mbuf */
441 	space = m->m_len - (hdrlen + ccmp.ic_header);
442 	for (;;) {
443 		if (space > data_len)
444 			space = data_len;
445 		/*
446 		 * Do full blocks.
447 		 */
448 		while (space >= AES_BLOCK_LEN) {
449 			CCMP_ENCRYPT(i, b, b0, pos, e, AES_BLOCK_LEN);
450 			pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
451 			data_len -= AES_BLOCK_LEN;
452 			i++;
453 		}
454 		if (data_len <= 0)		/* no more data */
455 			break;
456 		m = m->m_next;
457 		if (m == NULL) {		/* last buffer */
458 			if (space != 0) {
459 				/*
460 				 * Short last block.
461 				 */
462 				CCMP_ENCRYPT(i, b, b0, pos, e, space);
463 			}
464 			break;
465 		}
466 		if (space != 0) {
467 			uint8_t *pos_next;
468 			int space_next;
469 			int len, dl, sp;
470 			struct mbuf *n;
471 
472 			/*
473 			 * Block straddles one or more mbufs, gather data
474 			 * into the block buffer b, apply the cipher, then
475 			 * scatter the results back into the mbuf chain.
476 			 * The buffer will automatically get space bytes
477 			 * of data at offset 0 copied in+out by the
478 			 * CCMP_ENCRYPT request so we must take care of
479 			 * the remaining data.
480 			 */
481 			n = m;
482 			dl = data_len;
483 			sp = space;
484 			for (;;) {
485 				pos_next = mtod(n, uint8_t *);
486 				len = min(dl, AES_BLOCK_LEN);
487 				space_next = len > sp ? len - sp : 0;
488 				if (n->m_len >= space_next) {
489 					/*
490 					 * This mbuf has enough data; just grab
491 					 * what we need and stop.
492 					 */
493 					xor_block(b+sp, pos_next, space_next);
494 					break;
495 				}
496 				/*
497 				 * This mbuf's contents are insufficient,
498 				 * take 'em all and prepare to advance to
499 				 * the next mbuf.
500 				 */
501 				xor_block(b+sp, pos_next, n->m_len);
502 				sp += n->m_len, dl -= n->m_len;
503 				n = n->m_next;
504 				if (n == NULL)
505 					break;
506 			}
507 
508 			CCMP_ENCRYPT(i, b, b0, pos, e, space);
509 
510 			/* NB: just like above, but scatter data to mbufs */
511 			dl = data_len;
512 			sp = space;
513 			for (;;) {
514 				pos_next = mtod(m, uint8_t *);
515 				len = min(dl, AES_BLOCK_LEN);
516 				space_next = len > sp ? len - sp : 0;
517 				if (m->m_len >= space_next) {
518 					xor_block(pos_next, e+sp, space_next);
519 					break;
520 				}
521 				xor_block(pos_next, e+sp, m->m_len);
522 				sp += m->m_len, dl -= m->m_len;
523 				m = m->m_next;
524 				if (m == NULL)
525 					goto done;
526 			}
527 			/*
528 			 * Do bookkeeping.  m now points to the last mbuf
529 			 * we grabbed data from.  We know we consumed a
530 			 * full block of data as otherwise we'd have hit
531 			 * the end of the mbuf chain, so deduct from data_len.
532 			 * Otherwise advance the block number (i) and setup
533 			 * pos+space to reflect contents of the new mbuf.
534 			 */
535 			data_len -= AES_BLOCK_LEN;
536 			i++;
537 			pos = pos_next + space_next;
538 			space = m->m_len - space_next;
539 		} else {
540 			/*
541 			 * Setup for next buffer.
542 			 */
543 			pos = mtod(m, uint8_t *);
544 			space = m->m_len;
545 		}
546 	}
547 done:
548 	/* tack on MIC */
549 	xor_block(b, s0, ccmp.ic_trailer);
550 	return m_append(m0, ccmp.ic_trailer, b);
551 }
552 #undef CCMP_ENCRYPT
553 
554 #define	CCMP_DECRYPT(_i, _b, _b0, _pos, _a, _len) do {	\
555 	/* Decrypt, with counter */			\
556 	_b0[14] = (_i >> 8) & 0xff;			\
557 	_b0[15] = _i & 0xff;				\
558 	rijndael_encrypt(&ctx->cc_aes, _b0, _b);	\
559 	xor_block(_pos, _b, _len);			\
560 	/* Authentication */				\
561 	xor_block(_a, _pos, _len);			\
562 	rijndael_encrypt(&ctx->cc_aes, _a, _a);		\
563 } while (0)
564 
565 static int
566 ccmp_decrypt(struct ieee80211_key *key, u_int64_t pn, struct mbuf *m, int hdrlen)
567 {
568 	struct ccmp_ctx *ctx = key->wk_private;
569 	struct ieee80211vap *vap = ctx->cc_vap;
570 	struct ieee80211_frame *wh;
571 	uint8_t aad[2 * AES_BLOCK_LEN];
572 	uint8_t b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN], a[AES_BLOCK_LEN];
573 	uint8_t mic[AES_BLOCK_LEN];
574 	size_t data_len;
575 	int i;
576 	uint8_t *pos;
577 	u_int space;
578 
579 	ctx->cc_vap->iv_stats.is_crypto_ccmp++;
580 
581 	wh = mtod(m, struct ieee80211_frame *);
582 	data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header + ccmp.ic_trailer);
583 	ccmp_init_blocks(&ctx->cc_aes, wh, pn, data_len, b0, aad, a, b);
584 	m_copydata(m, m->m_pkthdr.len - ccmp.ic_trailer, ccmp.ic_trailer, mic);
585 	xor_block(mic, b, ccmp.ic_trailer);
586 
587 	i = 1;
588 	pos = mtod(m, uint8_t *) + hdrlen + ccmp.ic_header;
589 	space = m->m_len - (hdrlen + ccmp.ic_header);
590 	for (;;) {
591 		if (space > data_len)
592 			space = data_len;
593 		while (space >= AES_BLOCK_LEN) {
594 			CCMP_DECRYPT(i, b, b0, pos, a, AES_BLOCK_LEN);
595 			pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
596 			data_len -= AES_BLOCK_LEN;
597 			i++;
598 		}
599 		if (data_len <= 0)		/* no more data */
600 			break;
601 		m = m->m_next;
602 		if (m == NULL) {		/* last buffer */
603 			if (space != 0)		/* short last block */
604 				CCMP_DECRYPT(i, b, b0, pos, a, space);
605 			break;
606 		}
607 		if (space != 0) {
608 			uint8_t *pos_next;
609 			u_int space_next;
610 			u_int len;
611 
612 			/*
613 			 * Block straddles buffers, split references.  We
614 			 * do not handle splits that require >2 buffers
615 			 * since rx'd frames are never badly fragmented
616 			 * because drivers typically recv in clusters.
617 			 */
618 			pos_next = mtod(m, uint8_t *);
619 			len = min(data_len, AES_BLOCK_LEN);
620 			space_next = len > space ? len - space : 0;
621 			KASSERT(m->m_len >= space_next,
622 				("not enough data in following buffer, "
623 				"m_len %u need %u\n", m->m_len, space_next));
624 
625 			xor_block(b+space, pos_next, space_next);
626 			CCMP_DECRYPT(i, b, b0, pos, a, space);
627 			xor_block(pos_next, b+space, space_next);
628 			data_len -= len;
629 			i++;
630 
631 			pos = pos_next + space_next;
632 			space = m->m_len - space_next;
633 		} else {
634 			/*
635 			 * Setup for next buffer.
636 			 */
637 			pos = mtod(m, uint8_t *);
638 			space = m->m_len;
639 		}
640 	}
641 	if (memcmp(mic, a, ccmp.ic_trailer) != 0) {
642 		IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
643 		    "%s", "AES-CCM decrypt failed; MIC mismatch");
644 		vap->iv_stats.is_rx_ccmpmic++;
645 		return 0;
646 	}
647 	return 1;
648 }
649 #undef CCMP_DECRYPT
650 
651 /*
652  * Module glue.
653  */
654 IEEE80211_CRYPTO_MODULE(ccmp, 1);
655