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_var.h>
49 #include <net/if_media.h>
50 #include <net/ethernet.h>
51 
52 #include <netproto/802_11/ieee80211_var.h>
53 
54 #include <crypto/rijndael/rijndael.h>
55 
56 #define AES_BLOCK_LEN 16
57 
58 struct ccmp_ctx {
59 	struct ieee80211vap *cc_vap;	/* for diagnostics+statistics */
60 	struct ieee80211com *cc_ic;
61 	rijndael_ctx	     cc_aes;
62 };
63 
64 static	void *ccmp_attach(struct ieee80211vap *, struct ieee80211_key *);
65 static	void ccmp_detach(struct ieee80211_key *);
66 static	int ccmp_setkey(struct ieee80211_key *);
67 static	void ccmp_setiv(struct ieee80211_key *, uint8_t *);
68 static	int ccmp_encap(struct ieee80211_key *, struct mbuf *);
69 static	int ccmp_decap(struct ieee80211_key *, struct mbuf *, int);
70 static	int ccmp_enmic(struct ieee80211_key *, struct mbuf *, int);
71 static	int ccmp_demic(struct ieee80211_key *, struct mbuf *, int);
72 
73 static const struct ieee80211_cipher ccmp = {
74 	.ic_name	= "AES-CCM",
75 	.ic_cipher	= IEEE80211_CIPHER_AES_CCM,
76 	.ic_header	= IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN +
77 			  IEEE80211_WEP_EXTIVLEN,
78 	.ic_trailer	= IEEE80211_WEP_MICLEN,
79 	.ic_miclen	= 0,
80 	.ic_attach	= ccmp_attach,
81 	.ic_detach	= ccmp_detach,
82 	.ic_setkey	= ccmp_setkey,
83 	.ic_setiv	= ccmp_setiv,
84 	.ic_encap	= ccmp_encap,
85 	.ic_decap	= ccmp_decap,
86 	.ic_enmic	= ccmp_enmic,
87 	.ic_demic	= ccmp_demic,
88 };
89 
90 static	int ccmp_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
91 static	int ccmp_decrypt(struct ieee80211_key *, u_int64_t pn,
92 		struct mbuf *, int hdrlen);
93 
94 /* number of references from net80211 layer */
95 static	int nrefs = 0;
96 
97 static void *
98 ccmp_attach(struct ieee80211vap *vap, struct ieee80211_key *k)
99 {
100 	struct ccmp_ctx *ctx;
101 
102 #if defined(__DragonFly__)
103 	ctx = (struct ccmp_ctx *) kmalloc(sizeof(struct ccmp_ctx),
104 		M_80211_CRYPTO, M_INTWAIT | M_ZERO);
105 #else
106 	ctx = (struct ccmp_ctx *) IEEE80211_MALLOC(sizeof(struct ccmp_ctx),
107 		M_80211_CRYPTO, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
108 #endif
109 	if (ctx == NULL) {
110 		vap->iv_stats.is_crypto_nomem++;
111 		return NULL;
112 	}
113 	ctx->cc_vap = vap;
114 	ctx->cc_ic = vap->iv_ic;
115 	nrefs++;			/* NB: we assume caller locking */
116 	return ctx;
117 }
118 
119 static void
120 ccmp_detach(struct ieee80211_key *k)
121 {
122 	struct ccmp_ctx *ctx = k->wk_private;
123 
124 	IEEE80211_FREE(ctx, M_80211_CRYPTO);
125 	KASSERT(nrefs > 0, ("imbalanced attach/detach"));
126 	nrefs--;			/* NB: we assume caller locking */
127 }
128 
129 static int
130 ccmp_setkey(struct ieee80211_key *k)
131 {
132 	struct ccmp_ctx *ctx = k->wk_private;
133 
134 	if (k->wk_keylen != (128/NBBY)) {
135 		IEEE80211_DPRINTF(ctx->cc_vap, IEEE80211_MSG_CRYPTO,
136 			"%s: Invalid key length %u, expecting %u\n",
137 			__func__, k->wk_keylen, 128/NBBY);
138 		return 0;
139 	}
140 	if (k->wk_flags & IEEE80211_KEY_SWENCRYPT)
141 		rijndael_set_key(&ctx->cc_aes, k->wk_key, k->wk_keylen*NBBY);
142 	return 1;
143 }
144 
145 static void
146 ccmp_setiv(struct ieee80211_key *k, uint8_t *ivp)
147 {
148 	struct ccmp_ctx *ctx = k->wk_private;
149 	struct ieee80211vap *vap = ctx->cc_vap;
150 	uint8_t keyid;
151 
152 	keyid = ieee80211_crypto_get_keyid(vap, k) << 6;
153 
154 	k->wk_keytsc++;
155 	ivp[0] = k->wk_keytsc >> 0;		/* PN0 */
156 	ivp[1] = k->wk_keytsc >> 8;		/* PN1 */
157 	ivp[2] = 0;				/* Reserved */
158 	ivp[3] = keyid | IEEE80211_WEP_EXTIV;	/* KeyID | ExtID */
159 	ivp[4] = k->wk_keytsc >> 16;		/* PN2 */
160 	ivp[5] = k->wk_keytsc >> 24;		/* PN3 */
161 	ivp[6] = k->wk_keytsc >> 32;		/* PN4 */
162 	ivp[7] = k->wk_keytsc >> 40;		/* PN5 */
163 }
164 
165 /*
166  * Add privacy headers appropriate for the specified key.
167  */
168 static int
169 ccmp_encap(struct ieee80211_key *k, struct mbuf *m)
170 {
171 	struct ccmp_ctx *ctx = k->wk_private;
172 	struct ieee80211com *ic = ctx->cc_ic;
173 	uint8_t *ivp;
174 	int hdrlen;
175 
176 	hdrlen = ieee80211_hdrspace(ic, mtod(m, void *));
177 
178 	/*
179 	 * Copy down 802.11 header and add the IV, KeyID, and ExtIV.
180 	 */
181 	M_PREPEND(m, ccmp.ic_header, M_NOWAIT);
182 	if (m == NULL)
183 		return 0;
184 	ivp = mtod(m, uint8_t *);
185 	bcopy(ivp + ccmp.ic_header, ivp, hdrlen);
186 	ivp += hdrlen;
187 
188 	ccmp_setiv(k, ivp);
189 
190 	/*
191 	 * Finally, do software encrypt if needed.
192 	 */
193 	if ((k->wk_flags & IEEE80211_KEY_SWENCRYPT) &&
194 	    !ccmp_encrypt(k, m, hdrlen))
195 		return 0;
196 
197 	return 1;
198 }
199 
200 /*
201  * Add MIC to the frame as needed.
202  */
203 static int
204 ccmp_enmic(struct ieee80211_key *k, struct mbuf *m, int force)
205 {
206 
207 	return 1;
208 }
209 
210 static __inline uint64_t
211 READ_6(uint8_t b0, uint8_t b1, uint8_t b2, uint8_t b3, uint8_t b4, uint8_t b5)
212 {
213 	uint32_t iv32 = (b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24);
214 	uint16_t iv16 = (b4 << 0) | (b5 << 8);
215 	return (((uint64_t)iv16) << 32) | iv32;
216 }
217 
218 /*
219  * Validate and strip privacy headers (and trailer) for a
220  * received frame. The specified key should be correct but
221  * is also verified.
222  */
223 static int
224 ccmp_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen)
225 {
226 	struct ccmp_ctx *ctx = k->wk_private;
227 	struct ieee80211vap *vap = ctx->cc_vap;
228 	struct ieee80211_frame *wh;
229 	uint8_t *ivp, tid;
230 	uint64_t pn;
231 
232 	/*
233 	 * Header should have extended IV and sequence number;
234 	 * verify the former and validate the latter.
235 	 */
236 	wh = mtod(m, struct ieee80211_frame *);
237 	ivp = mtod(m, uint8_t *) + hdrlen;
238 	if ((ivp[IEEE80211_WEP_IVLEN] & IEEE80211_WEP_EXTIV) == 0) {
239 		/*
240 		 * No extended IV; discard frame.
241 		 */
242 		IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
243 			"%s", "missing ExtIV for AES-CCM cipher");
244 		vap->iv_stats.is_rx_ccmpformat++;
245 		return 0;
246 	}
247 	tid = ieee80211_gettid(wh);
248 	pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
249 	if (pn <= k->wk_keyrsc[tid] &&
250 	    (k->wk_flags & IEEE80211_KEY_NOREPLAY) == 0) {
251 		/*
252 		 * Replay violation.
253 		 */
254 		ieee80211_notify_replay_failure(vap, wh, k, pn, tid);
255 		vap->iv_stats.is_rx_ccmpreplay++;
256 		return 0;
257 	}
258 
259 	/*
260 	 * Check if the device handled the decrypt in hardware.
261 	 * If so we just strip the header; otherwise we need to
262 	 * handle the decrypt in software.  Note that for the
263 	 * latter we leave the header in place for use in the
264 	 * decryption work.
265 	 */
266 	if ((k->wk_flags & IEEE80211_KEY_SWDECRYPT) &&
267 	    !ccmp_decrypt(k, pn, m, hdrlen))
268 		return 0;
269 
270 	/*
271 	 * Copy up 802.11 header and strip crypto bits.
272 	 */
273 	bcopy(mtod(m, void *), mtod(m, uint8_t *) + ccmp.ic_header, hdrlen);
274 	m_adj(m, ccmp.ic_header);
275 	m_adj(m, -ccmp.ic_trailer);
276 
277 	/*
278 	 * Ok to update rsc now.
279 	 */
280 	k->wk_keyrsc[tid] = pn;
281 
282 	return 1;
283 }
284 
285 /*
286  * Verify and strip MIC from the frame.
287  */
288 static int
289 ccmp_demic(struct ieee80211_key *k, struct mbuf *m, int force)
290 {
291 	return 1;
292 }
293 
294 static __inline void
295 xor_block(uint8_t *b, const uint8_t *a, size_t len)
296 {
297 	int i;
298 	for (i = 0; i < len; i++)
299 		b[i] ^= a[i];
300 }
301 
302 /*
303  * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
304  *
305  * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
306  *
307  * This program is free software; you can redistribute it and/or modify
308  * it under the terms of the GNU General Public License version 2 as
309  * published by the Free Software Foundation. See README and COPYING for
310  * more details.
311  *
312  * Alternatively, this software may be distributed under the terms of BSD
313  * license.
314  */
315 
316 static void
317 ccmp_init_blocks(rijndael_ctx *ctx, struct ieee80211_frame *wh,
318 	u_int64_t pn, size_t dlen,
319 	uint8_t b0[AES_BLOCK_LEN], uint8_t aad[2 * AES_BLOCK_LEN],
320 	uint8_t auth[AES_BLOCK_LEN], uint8_t s0[AES_BLOCK_LEN])
321 {
322 #define	IS_QOS_DATA(wh)	IEEE80211_QOS_HAS_SEQ(wh)
323 
324 	/* CCM Initial Block:
325 	 * Flag (Include authentication header, M=3 (8-octet MIC),
326 	 *       L=1 (2-octet Dlen))
327 	 * Nonce: 0x00 | A2 | PN
328 	 * Dlen */
329 	b0[0] = 0x59;
330 	/* NB: b0[1] set below */
331 	IEEE80211_ADDR_COPY(b0 + 2, wh->i_addr2);
332 	b0[8] = pn >> 40;
333 	b0[9] = pn >> 32;
334 	b0[10] = pn >> 24;
335 	b0[11] = pn >> 16;
336 	b0[12] = pn >> 8;
337 	b0[13] = pn >> 0;
338 	b0[14] = (dlen >> 8) & 0xff;
339 	b0[15] = dlen & 0xff;
340 
341 	/* AAD:
342 	 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
343 	 * A1 | A2 | A3
344 	 * SC with bits 4..15 (seq#) masked to zero
345 	 * A4 (if present)
346 	 * QC (if present)
347 	 */
348 	aad[0] = 0;	/* AAD length >> 8 */
349 	/* NB: aad[1] set below */
350 	aad[2] = wh->i_fc[0] & 0x8f;	/* XXX magic #s */
351 	aad[3] = wh->i_fc[1] & 0xc7;	/* XXX magic #s */
352 	/* NB: we know 3 addresses are contiguous */
353 	memcpy(aad + 4, wh->i_addr1, 3 * IEEE80211_ADDR_LEN);
354 	aad[22] = wh->i_seq[0] & IEEE80211_SEQ_FRAG_MASK;
355 	aad[23] = 0; /* all bits masked */
356 	/*
357 	 * Construct variable-length portion of AAD based
358 	 * on whether this is a 4-address frame/QOS frame.
359 	 * We always zero-pad to 32 bytes before running it
360 	 * through the cipher.
361 	 *
362 	 * We also fill in the priority bits of the CCM
363 	 * initial block as we know whether or not we have
364 	 * a QOS frame.
365 	 */
366 	if (IEEE80211_IS_DSTODS(wh)) {
367 		IEEE80211_ADDR_COPY(aad + 24,
368 			((struct ieee80211_frame_addr4 *)wh)->i_addr4);
369 		if (IS_QOS_DATA(wh)) {
370 			struct ieee80211_qosframe_addr4 *qwh4 =
371 				(struct ieee80211_qosframe_addr4 *) wh;
372 			aad[30] = qwh4->i_qos[0] & 0x0f;/* just priority bits */
373 			aad[31] = 0;
374 			b0[1] = aad[30];
375 			aad[1] = 22 + IEEE80211_ADDR_LEN + 2;
376 		} else {
377 			*(uint16_t *)&aad[30] = 0;
378 			b0[1] = 0;
379 			aad[1] = 22 + IEEE80211_ADDR_LEN;
380 		}
381 	} else {
382 		if (IS_QOS_DATA(wh)) {
383 			struct ieee80211_qosframe *qwh =
384 				(struct ieee80211_qosframe*) wh;
385 			aad[24] = qwh->i_qos[0] & 0x0f;	/* just priority bits */
386 			aad[25] = 0;
387 			b0[1] = aad[24];
388 			aad[1] = 22 + 2;
389 		} else {
390 			*(uint16_t *)&aad[24] = 0;
391 			b0[1] = 0;
392 			aad[1] = 22;
393 		}
394 		*(uint16_t *)&aad[26] = 0;
395 		*(uint32_t *)&aad[28] = 0;
396 	}
397 
398 	/* Start with the first block and AAD */
399 	rijndael_encrypt(ctx, b0, auth);
400 	xor_block(auth, aad, AES_BLOCK_LEN);
401 	rijndael_encrypt(ctx, auth, auth);
402 	xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
403 	rijndael_encrypt(ctx, auth, auth);
404 	b0[0] &= 0x07;
405 	b0[14] = b0[15] = 0;
406 	rijndael_encrypt(ctx, b0, s0);
407 #undef	IS_QOS_DATA
408 }
409 
410 #define	CCMP_ENCRYPT(_i, _b, _b0, _pos, _e, _len) do {	\
411 	/* Authentication */				\
412 	xor_block(_b, _pos, _len);			\
413 	rijndael_encrypt(&ctx->cc_aes, _b, _b);		\
414 	/* Encryption, with counter */			\
415 	_b0[14] = (_i >> 8) & 0xff;			\
416 	_b0[15] = _i & 0xff;				\
417 	rijndael_encrypt(&ctx->cc_aes, _b0, _e);	\
418 	xor_block(_pos, _e, _len);			\
419 } while (0)
420 
421 static int
422 ccmp_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
423 {
424 	struct ccmp_ctx *ctx = key->wk_private;
425 	struct ieee80211_frame *wh;
426 	struct mbuf *m = m0;
427 	int data_len, i, space;
428 	uint8_t aad[2 * AES_BLOCK_LEN], b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN],
429 		e[AES_BLOCK_LEN], s0[AES_BLOCK_LEN];
430 	uint8_t *pos;
431 
432 	ctx->cc_vap->iv_stats.is_crypto_ccmp++;
433 
434 	wh = mtod(m, struct ieee80211_frame *);
435 	data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header);
436 	ccmp_init_blocks(&ctx->cc_aes, wh, key->wk_keytsc,
437 		data_len, b0, aad, b, s0);
438 
439 	i = 1;
440 	pos = mtod(m, uint8_t *) + hdrlen + ccmp.ic_header;
441 	/* NB: assumes header is entirely in first mbuf */
442 	space = m->m_len - (hdrlen + ccmp.ic_header);
443 	for (;;) {
444 		if (space > data_len)
445 			space = data_len;
446 		/*
447 		 * Do full blocks.
448 		 */
449 		while (space >= AES_BLOCK_LEN) {
450 			CCMP_ENCRYPT(i, b, b0, pos, e, AES_BLOCK_LEN);
451 			pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
452 			data_len -= AES_BLOCK_LEN;
453 			i++;
454 		}
455 		if (data_len <= 0)		/* no more data */
456 			break;
457 		m = m->m_next;
458 		if (m == NULL) {		/* last buffer */
459 			if (space != 0) {
460 				/*
461 				 * Short last block.
462 				 */
463 				CCMP_ENCRYPT(i, b, b0, pos, e, space);
464 			}
465 			break;
466 		}
467 		if (space != 0) {
468 			uint8_t *pos_next;
469 			int space_next;
470 			int len, dl, sp;
471 			struct mbuf *n;
472 
473 			/*
474 			 * Block straddles one or more mbufs, gather data
475 			 * into the block buffer b, apply the cipher, then
476 			 * scatter the results back into the mbuf chain.
477 			 * The buffer will automatically get space bytes
478 			 * of data at offset 0 copied in+out by the
479 			 * CCMP_ENCRYPT request so we must take care of
480 			 * the remaining data.
481 			 */
482 			n = m;
483 			dl = data_len;
484 			sp = space;
485 			for (;;) {
486 				pos_next = mtod(n, uint8_t *);
487 				len = min(dl, AES_BLOCK_LEN);
488 				space_next = len > sp ? len - sp : 0;
489 				if (n->m_len >= space_next) {
490 					/*
491 					 * This mbuf has enough data; just grab
492 					 * what we need and stop.
493 					 */
494 					xor_block(b+sp, pos_next, space_next);
495 					break;
496 				}
497 				/*
498 				 * This mbuf's contents are insufficient,
499 				 * take 'em all and prepare to advance to
500 				 * the next mbuf.
501 				 */
502 				xor_block(b+sp, pos_next, n->m_len);
503 				sp += n->m_len, dl -= n->m_len;
504 				n = n->m_next;
505 				if (n == NULL)
506 					break;
507 			}
508 
509 			CCMP_ENCRYPT(i, b, b0, pos, e, space);
510 
511 			/* NB: just like above, but scatter data to mbufs */
512 			dl = data_len;
513 			sp = space;
514 			for (;;) {
515 				pos_next = mtod(m, uint8_t *);
516 				len = min(dl, AES_BLOCK_LEN);
517 				space_next = len > sp ? len - sp : 0;
518 				if (m->m_len >= space_next) {
519 					xor_block(pos_next, e+sp, space_next);
520 					break;
521 				}
522 				xor_block(pos_next, e+sp, m->m_len);
523 				sp += m->m_len, dl -= m->m_len;
524 				m = m->m_next;
525 				if (m == NULL)
526 					goto done;
527 			}
528 			/*
529 			 * Do bookkeeping.  m now points to the last mbuf
530 			 * we grabbed data from.  We know we consumed a
531 			 * full block of data as otherwise we'd have hit
532 			 * the end of the mbuf chain, so deduct from data_len.
533 			 * Otherwise advance the block number (i) and setup
534 			 * pos+space to reflect contents of the new mbuf.
535 			 */
536 			data_len -= AES_BLOCK_LEN;
537 			i++;
538 			pos = pos_next + space_next;
539 			space = m->m_len - space_next;
540 		} else {
541 			/*
542 			 * Setup for next buffer.
543 			 */
544 			pos = mtod(m, uint8_t *);
545 			space = m->m_len;
546 		}
547 	}
548 done:
549 	/* tack on MIC */
550 	xor_block(b, s0, ccmp.ic_trailer);
551 	return m_append(m0, ccmp.ic_trailer, b);
552 }
553 #undef CCMP_ENCRYPT
554 
555 #define	CCMP_DECRYPT(_i, _b, _b0, _pos, _a, _len) do {	\
556 	/* Decrypt, with counter */			\
557 	_b0[14] = (_i >> 8) & 0xff;			\
558 	_b0[15] = _i & 0xff;				\
559 	rijndael_encrypt(&ctx->cc_aes, _b0, _b);	\
560 	xor_block(_pos, _b, _len);			\
561 	/* Authentication */				\
562 	xor_block(_a, _pos, _len);			\
563 	rijndael_encrypt(&ctx->cc_aes, _a, _a);		\
564 } while (0)
565 
566 static int
567 ccmp_decrypt(struct ieee80211_key *key, u_int64_t pn, struct mbuf *m, int hdrlen)
568 {
569 	struct ccmp_ctx *ctx = key->wk_private;
570 	struct ieee80211vap *vap = ctx->cc_vap;
571 	struct ieee80211_frame *wh;
572 	uint8_t aad[2 * AES_BLOCK_LEN];
573 	uint8_t b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN], a[AES_BLOCK_LEN];
574 	uint8_t mic[AES_BLOCK_LEN];
575 	size_t data_len;
576 	int i;
577 	uint8_t *pos;
578 	u_int space;
579 
580 	ctx->cc_vap->iv_stats.is_crypto_ccmp++;
581 
582 	wh = mtod(m, struct ieee80211_frame *);
583 	data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header + ccmp.ic_trailer);
584 	ccmp_init_blocks(&ctx->cc_aes, wh, pn, data_len, b0, aad, a, b);
585 	m_copydata(m, m->m_pkthdr.len - ccmp.ic_trailer, ccmp.ic_trailer, mic);
586 	xor_block(mic, b, ccmp.ic_trailer);
587 
588 	i = 1;
589 	pos = mtod(m, uint8_t *) + hdrlen + ccmp.ic_header;
590 	space = m->m_len - (hdrlen + ccmp.ic_header);
591 	for (;;) {
592 		if (space > data_len)
593 			space = data_len;
594 		while (space >= AES_BLOCK_LEN) {
595 			CCMP_DECRYPT(i, b, b0, pos, a, AES_BLOCK_LEN);
596 			pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
597 			data_len -= AES_BLOCK_LEN;
598 			i++;
599 		}
600 		if (data_len <= 0)		/* no more data */
601 			break;
602 		m = m->m_next;
603 		if (m == NULL) {		/* last buffer */
604 			if (space != 0)		/* short last block */
605 				CCMP_DECRYPT(i, b, b0, pos, a, space);
606 			break;
607 		}
608 		if (space != 0) {
609 			uint8_t *pos_next;
610 			u_int space_next;
611 			u_int len;
612 
613 			/*
614 			 * Block straddles buffers, split references.  We
615 			 * do not handle splits that require >2 buffers
616 			 * since rx'd frames are never badly fragmented
617 			 * because drivers typically recv in clusters.
618 			 */
619 			pos_next = mtod(m, uint8_t *);
620 			len = min(data_len, AES_BLOCK_LEN);
621 			space_next = len > space ? len - space : 0;
622 			KASSERT(m->m_len >= space_next,
623 				("not enough data in following buffer, "
624 				"m_len %u need %u\n", m->m_len, space_next));
625 
626 			xor_block(b+space, pos_next, space_next);
627 			CCMP_DECRYPT(i, b, b0, pos, a, space);
628 			xor_block(pos_next, b+space, space_next);
629 			data_len -= len;
630 			i++;
631 
632 			pos = pos_next + space_next;
633 			space = m->m_len - space_next;
634 		} else {
635 			/*
636 			 * Setup for next buffer.
637 			 */
638 			pos = mtod(m, uint8_t *);
639 			space = m->m_len;
640 		}
641 	}
642 	if (memcmp(mic, a, ccmp.ic_trailer) != 0) {
643 		IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
644 		    "%s", "AES-CCM decrypt failed; MIC mismatch");
645 		vap->iv_stats.is_rx_ccmpmic++;
646 		return 0;
647 	}
648 	return 1;
649 }
650 #undef CCMP_DECRYPT
651 
652 /*
653  * Module glue.
654  */
655 IEEE80211_CRYPTO_MODULE(ccmp, 1);
656