xref: /freebsd/sys/net80211/ieee80211_crypto_ccmp.c (revision 3642298923e528d795e3a30ec165d2b469e28b40)
1 /*-
2  * Copyright (c) 2002-2005 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  * 3. The name of the author may not be used to endorse or promote products
14  *    derived from this software without specific prior written permission.
15  *
16  * Alternatively, this software may be distributed under the terms of the
17  * GNU General Public License ("GPL") version 2 as published by the Free
18  * Software Foundation.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34 
35 /*
36  * IEEE 802.11i AES-CCMP crypto support.
37  *
38  * Part of this module is derived from similar code in the Host
39  * AP driver. The code is used with the consent of the author and
40  * it's license is included below.
41  */
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/mbuf.h>
45 #include <sys/malloc.h>
46 #include <sys/kernel.h>
47 #include <sys/module.h>
48 
49 #include <sys/socket.h>
50 
51 #include <net/if.h>
52 #include <net/if_media.h>
53 #include <net/ethernet.h>
54 
55 #include <net80211/ieee80211_var.h>
56 
57 #include <crypto/rijndael/rijndael.h>
58 
59 #define AES_BLOCK_LEN 16
60 
61 struct ccmp_ctx {
62 	struct ieee80211com *cc_ic;	/* for diagnostics */
63 	rijndael_ctx	     cc_aes;
64 };
65 
66 static	void *ccmp_attach(struct ieee80211com *, struct ieee80211_key *);
67 static	void ccmp_detach(struct ieee80211_key *);
68 static	int ccmp_setkey(struct ieee80211_key *);
69 static	int ccmp_encap(struct ieee80211_key *k, struct mbuf *, u_int8_t keyid);
70 static	int ccmp_decap(struct ieee80211_key *, struct mbuf *, int);
71 static	int ccmp_enmic(struct ieee80211_key *, struct mbuf *, int);
72 static	int ccmp_demic(struct ieee80211_key *, struct mbuf *, int);
73 
74 static const struct ieee80211_cipher ccmp = {
75 	.ic_name	= "AES-CCM",
76 	.ic_cipher	= IEEE80211_CIPHER_AES_CCM,
77 	.ic_header	= IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN +
78 			  IEEE80211_WEP_EXTIVLEN,
79 	.ic_trailer	= IEEE80211_WEP_MICLEN,
80 	.ic_miclen	= 0,
81 	.ic_attach	= ccmp_attach,
82 	.ic_detach	= ccmp_detach,
83 	.ic_setkey	= ccmp_setkey,
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 static void *
95 ccmp_attach(struct ieee80211com *ic, struct ieee80211_key *k)
96 {
97 	struct ccmp_ctx *ctx;
98 
99 	MALLOC(ctx, struct ccmp_ctx *, sizeof(struct ccmp_ctx),
100 		M_DEVBUF, M_NOWAIT | M_ZERO);
101 	if (ctx == NULL) {
102 		ic->ic_stats.is_crypto_nomem++;
103 		return NULL;
104 	}
105 	ctx->cc_ic = ic;
106 	return ctx;
107 }
108 
109 static void
110 ccmp_detach(struct ieee80211_key *k)
111 {
112 	struct ccmp_ctx *ctx = k->wk_private;
113 
114 	FREE(ctx, M_DEVBUF);
115 }
116 
117 static int
118 ccmp_setkey(struct ieee80211_key *k)
119 {
120 	struct ccmp_ctx *ctx = k->wk_private;
121 
122 	if (k->wk_keylen != (128/NBBY)) {
123 		IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
124 			"%s: Invalid key length %u, expecting %u\n",
125 			__func__, k->wk_keylen, 128/NBBY);
126 		return 0;
127 	}
128 	if (k->wk_flags & IEEE80211_KEY_SWCRYPT)
129 		rijndael_set_key(&ctx->cc_aes, k->wk_key, k->wk_keylen*NBBY);
130 	return 1;
131 }
132 
133 /*
134  * Add privacy headers appropriate for the specified key.
135  */
136 static int
137 ccmp_encap(struct ieee80211_key *k, struct mbuf *m, u_int8_t keyid)
138 {
139 	struct ccmp_ctx *ctx = k->wk_private;
140 	struct ieee80211com *ic = ctx->cc_ic;
141 	u_int8_t *ivp;
142 	int hdrlen;
143 
144 	hdrlen = ieee80211_hdrspace(ic, mtod(m, void *));
145 
146 	/*
147 	 * Copy down 802.11 header and add the IV, KeyID, and ExtIV.
148 	 */
149 	M_PREPEND(m, ccmp.ic_header, M_NOWAIT);
150 	if (m == NULL)
151 		return 0;
152 	ivp = mtod(m, u_int8_t *);
153 	ovbcopy(ivp + ccmp.ic_header, ivp, hdrlen);
154 	ivp += hdrlen;
155 
156 	k->wk_keytsc++;		/* XXX wrap at 48 bits */
157 	ivp[0] = k->wk_keytsc >> 0;		/* PN0 */
158 	ivp[1] = k->wk_keytsc >> 8;		/* PN1 */
159 	ivp[2] = 0;				/* Reserved */
160 	ivp[3] = keyid | IEEE80211_WEP_EXTIV;	/* KeyID | ExtID */
161 	ivp[4] = k->wk_keytsc >> 16;		/* PN2 */
162 	ivp[5] = k->wk_keytsc >> 24;		/* PN3 */
163 	ivp[6] = k->wk_keytsc >> 32;		/* PN4 */
164 	ivp[7] = k->wk_keytsc >> 40;		/* PN5 */
165 
166 	/*
167 	 * Finally, do software encrypt if neeed.
168 	 */
169 	if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
170 	    !ccmp_encrypt(k, m, hdrlen))
171 		return 0;
172 
173 	return 1;
174 }
175 
176 /*
177  * Add MIC to the frame as needed.
178  */
179 static int
180 ccmp_enmic(struct ieee80211_key *k, struct mbuf *m, int force)
181 {
182 
183 	return 1;
184 }
185 
186 static __inline uint64_t
187 READ_6(uint8_t b0, uint8_t b1, uint8_t b2, uint8_t b3, uint8_t b4, uint8_t b5)
188 {
189 	uint32_t iv32 = (b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24);
190 	uint16_t iv16 = (b4 << 0) | (b5 << 8);
191 	return (((uint64_t)iv16) << 32) | iv32;
192 }
193 
194 /*
195  * Validate and strip privacy headers (and trailer) for a
196  * received frame. The specified key should be correct but
197  * is also verified.
198  */
199 static int
200 ccmp_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen)
201 {
202 	struct ccmp_ctx *ctx = k->wk_private;
203 	struct ieee80211_frame *wh;
204 	uint8_t *ivp;
205 	uint64_t pn;
206 
207 	/*
208 	 * Header should have extended IV and sequence number;
209 	 * verify the former and validate the latter.
210 	 */
211 	wh = mtod(m, struct ieee80211_frame *);
212 	ivp = mtod(m, uint8_t *) + hdrlen;
213 	if ((ivp[IEEE80211_WEP_IVLEN] & IEEE80211_WEP_EXTIV) == 0) {
214 		/*
215 		 * No extended IV; discard frame.
216 		 */
217 		IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
218 			"[%s] Missing ExtIV for AES-CCM cipher\n",
219 			ether_sprintf(wh->i_addr2));
220 		ctx->cc_ic->ic_stats.is_rx_ccmpformat++;
221 		return 0;
222 	}
223 	pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
224 	if (pn <= k->wk_keyrsc) {
225 		/*
226 		 * Replay violation.
227 		 */
228 		ieee80211_notify_replay_failure(ctx->cc_ic, wh, k, pn);
229 		ctx->cc_ic->ic_stats.is_rx_ccmpreplay++;
230 		return 0;
231 	}
232 
233 	/*
234 	 * Check if the device handled the decrypt in hardware.
235 	 * If so we just strip the header; otherwise we need to
236 	 * handle the decrypt in software.  Note that for the
237 	 * latter we leave the header in place for use in the
238 	 * decryption work.
239 	 */
240 	if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
241 	    !ccmp_decrypt(k, pn, m, hdrlen))
242 		return 0;
243 
244 	/*
245 	 * Copy up 802.11 header and strip crypto bits.
246 	 */
247 	ovbcopy(mtod(m, void *), mtod(m, u_int8_t *) + ccmp.ic_header, hdrlen);
248 	m_adj(m, ccmp.ic_header);
249 	m_adj(m, -ccmp.ic_trailer);
250 
251 	/*
252 	 * Ok to update rsc now.
253 	 */
254 	k->wk_keyrsc = pn;
255 
256 	return 1;
257 }
258 
259 /*
260  * Verify and strip MIC from the frame.
261  */
262 static int
263 ccmp_demic(struct ieee80211_key *k, struct mbuf *m, int force)
264 {
265 	return 1;
266 }
267 
268 static __inline void
269 xor_block(uint8_t *b, const uint8_t *a, size_t len)
270 {
271 	int i;
272 	for (i = 0; i < len; i++)
273 		b[i] ^= a[i];
274 }
275 
276 /*
277  * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
278  *
279  * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
280  *
281  * This program is free software; you can redistribute it and/or modify
282  * it under the terms of the GNU General Public License version 2 as
283  * published by the Free Software Foundation. See README and COPYING for
284  * more details.
285  *
286  * Alternatively, this software may be distributed under the terms of BSD
287  * license.
288  */
289 
290 static void
291 ccmp_init_blocks(rijndael_ctx *ctx, struct ieee80211_frame *wh,
292 	u_int64_t pn, size_t dlen,
293 	uint8_t b0[AES_BLOCK_LEN], uint8_t aad[2 * AES_BLOCK_LEN],
294 	uint8_t auth[AES_BLOCK_LEN], uint8_t s0[AES_BLOCK_LEN])
295 {
296 #define	IS_4ADDRESS(wh) \
297 	((wh->i_fc[1] & IEEE80211_FC1_DIR_MASK) == IEEE80211_FC1_DIR_DSTODS)
298 #define	IS_QOS_DATA(wh)	IEEE80211_QOS_HAS_SEQ(wh)
299 
300 	/* CCM Initial Block:
301 	 * Flag (Include authentication header, M=3 (8-octet MIC),
302 	 *       L=1 (2-octet Dlen))
303 	 * Nonce: 0x00 | A2 | PN
304 	 * Dlen */
305 	b0[0] = 0x59;
306 	/* NB: b0[1] set below */
307 	IEEE80211_ADDR_COPY(b0 + 2, wh->i_addr2);
308 	b0[8] = pn >> 40;
309 	b0[9] = pn >> 32;
310 	b0[10] = pn >> 24;
311 	b0[11] = pn >> 16;
312 	b0[12] = pn >> 8;
313 	b0[13] = pn >> 0;
314 	b0[14] = (dlen >> 8) & 0xff;
315 	b0[15] = dlen & 0xff;
316 
317 	/* AAD:
318 	 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
319 	 * A1 | A2 | A3
320 	 * SC with bits 4..15 (seq#) masked to zero
321 	 * A4 (if present)
322 	 * QC (if present)
323 	 */
324 	aad[0] = 0;	/* AAD length >> 8 */
325 	/* NB: aad[1] set below */
326 	aad[2] = wh->i_fc[0] & 0x8f;	/* XXX magic #s */
327 	aad[3] = wh->i_fc[1] & 0xc7;	/* XXX magic #s */
328 	/* NB: we know 3 addresses are contiguous */
329 	memcpy(aad + 4, wh->i_addr1, 3 * IEEE80211_ADDR_LEN);
330 	aad[22] = wh->i_seq[0] & IEEE80211_SEQ_FRAG_MASK;
331 	aad[23] = 0; /* all bits masked */
332 	/*
333 	 * Construct variable-length portion of AAD based
334 	 * on whether this is a 4-address frame/QOS frame.
335 	 * We always zero-pad to 32 bytes before running it
336 	 * through the cipher.
337 	 *
338 	 * We also fill in the priority bits of the CCM
339 	 * initial block as we know whether or not we have
340 	 * a QOS frame.
341 	 */
342 	if (IS_4ADDRESS(wh)) {
343 		IEEE80211_ADDR_COPY(aad + 24,
344 			((struct ieee80211_frame_addr4 *)wh)->i_addr4);
345 		if (IS_QOS_DATA(wh)) {
346 			struct ieee80211_qosframe_addr4 *qwh4 =
347 				(struct ieee80211_qosframe_addr4 *) wh;
348 			aad[30] = qwh4->i_qos[0] & 0x0f;/* just priority bits */
349 			aad[31] = 0;
350 			b0[1] = aad[30];
351 			aad[1] = 22 + IEEE80211_ADDR_LEN + 2;
352 		} else {
353 			*(u_int16_t *)&aad[30] = 0;
354 			b0[1] = 0;
355 			aad[1] = 22 + IEEE80211_ADDR_LEN;
356 		}
357 	} else {
358 		if (IS_QOS_DATA(wh)) {
359 			struct ieee80211_qosframe *qwh =
360 				(struct ieee80211_qosframe*) wh;
361 			aad[24] = qwh->i_qos[0] & 0x0f;	/* just priority bits */
362 			aad[25] = 0;
363 			b0[1] = aad[24];
364 			aad[1] = 22 + 2;
365 		} else {
366 			*(u_int16_t *)&aad[24] = 0;
367 			b0[1] = 0;
368 			aad[1] = 22;
369 		}
370 		*(u_int16_t *)&aad[26] = 0;
371 		*(u_int32_t *)&aad[28] = 0;
372 	}
373 
374 	/* Start with the first block and AAD */
375 	rijndael_encrypt(ctx, b0, auth);
376 	xor_block(auth, aad, AES_BLOCK_LEN);
377 	rijndael_encrypt(ctx, auth, auth);
378 	xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
379 	rijndael_encrypt(ctx, auth, auth);
380 	b0[0] &= 0x07;
381 	b0[14] = b0[15] = 0;
382 	rijndael_encrypt(ctx, b0, s0);
383 #undef	IS_QOS_DATA
384 #undef	IS_4ADDRESS
385 }
386 
387 #define	CCMP_ENCRYPT(_i, _b, _b0, _pos, _e, _len) do {	\
388 	/* Authentication */				\
389 	xor_block(_b, _pos, _len);			\
390 	rijndael_encrypt(&ctx->cc_aes, _b, _b);		\
391 	/* Encryption, with counter */			\
392 	_b0[14] = (_i >> 8) & 0xff;			\
393 	_b0[15] = _i & 0xff;				\
394 	rijndael_encrypt(&ctx->cc_aes, _b0, _e);	\
395 	xor_block(_pos, _e, _len);			\
396 } while (0)
397 
398 static int
399 ccmp_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen)
400 {
401 	struct ccmp_ctx *ctx = key->wk_private;
402 	struct ieee80211_frame *wh;
403 	struct mbuf *m = m0;
404 	int data_len, i, space;
405 	uint8_t aad[2 * AES_BLOCK_LEN], b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN],
406 		e[AES_BLOCK_LEN], s0[AES_BLOCK_LEN];
407 	uint8_t *pos;
408 
409 	ctx->cc_ic->ic_stats.is_crypto_ccmp++;
410 
411 	wh = mtod(m, struct ieee80211_frame *);
412 	data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header);
413 	ccmp_init_blocks(&ctx->cc_aes, wh, key->wk_keytsc,
414 		data_len, b0, aad, b, s0);
415 
416 	i = 1;
417 	pos = mtod(m, uint8_t *) + hdrlen + ccmp.ic_header;
418 	/* NB: assumes header is entirely in first mbuf */
419 	space = m->m_len - (hdrlen + ccmp.ic_header);
420 	for (;;) {
421 		if (space > data_len)
422 			space = data_len;
423 		/*
424 		 * Do full blocks.
425 		 */
426 		while (space >= AES_BLOCK_LEN) {
427 			CCMP_ENCRYPT(i, b, b0, pos, e, AES_BLOCK_LEN);
428 			pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
429 			data_len -= AES_BLOCK_LEN;
430 			i++;
431 		}
432 		if (data_len <= 0)		/* no more data */
433 			break;
434 		m = m->m_next;
435 		if (m == NULL) {		/* last buffer */
436 			if (space != 0) {
437 				/*
438 				 * Short last block.
439 				 */
440 				CCMP_ENCRYPT(i, b, b0, pos, e, space);
441 			}
442 			break;
443 		}
444 		if (space != 0) {
445 			uint8_t *pos_next;
446 			int space_next;
447 			int len, dl, sp;
448 			struct mbuf *n;
449 
450 			/*
451 			 * Block straddles one or more mbufs, gather data
452 			 * into the block buffer b, apply the cipher, then
453 			 * scatter the results back into the mbuf chain.
454 			 * The buffer will automatically get space bytes
455 			 * of data at offset 0 copied in+out by the
456 			 * CCMP_ENCRYPT request so we must take care of
457 			 * the remaining data.
458 			 */
459 			n = m;
460 			dl = data_len;
461 			sp = space;
462 			for (;;) {
463 				pos_next = mtod(n, uint8_t *);
464 				len = min(dl, AES_BLOCK_LEN);
465 				space_next = len > sp ? len - sp : 0;
466 				if (n->m_len >= space_next) {
467 					/*
468 					 * This mbuf has enough data; just grab
469 					 * what we need and stop.
470 					 */
471 					xor_block(b+sp, pos_next, space_next);
472 					break;
473 				}
474 				/*
475 				 * This mbuf's contents are insufficient,
476 				 * take 'em all and prepare to advance to
477 				 * the next mbuf.
478 				 */
479 				xor_block(b+sp, pos_next, n->m_len);
480 				sp += n->m_len, dl -= n->m_len;
481 				n = n->m_next;
482 				if (n == NULL)
483 					break;
484 			}
485 
486 			CCMP_ENCRYPT(i, b, b0, pos, e, space);
487 
488 			/* NB: just like above, but scatter data to mbufs */
489 			dl = data_len;
490 			sp = space;
491 			for (;;) {
492 				pos_next = mtod(m, uint8_t *);
493 				len = min(dl, AES_BLOCK_LEN);
494 				space_next = len > sp ? len - sp : 0;
495 				if (m->m_len >= space_next) {
496 					xor_block(pos_next, e+sp, space_next);
497 					break;
498 				}
499 				xor_block(pos_next, e+sp, m->m_len);
500 				sp += m->m_len, dl -= m->m_len;
501 				m = m->m_next;
502 				if (m == NULL)
503 					goto done;
504 			}
505 			/*
506 			 * Do bookkeeping.  m now points to the last mbuf
507 			 * we grabbed data from.  We know we consumed a
508 			 * full block of data as otherwise we'd have hit
509 			 * the end of the mbuf chain, so deduct from data_len.
510 			 * Otherwise advance the block number (i) and setup
511 			 * pos+space to reflect contents of the new mbuf.
512 			 */
513 			data_len -= AES_BLOCK_LEN;
514 			i++;
515 			pos = pos_next + space_next;
516 			space = m->m_len - space_next;
517 		} else {
518 			/*
519 			 * Setup for next buffer.
520 			 */
521 			pos = mtod(m, uint8_t *);
522 			space = m->m_len;
523 		}
524 	}
525 done:
526 	/* tack on MIC */
527 	xor_block(b, s0, ccmp.ic_trailer);
528 	return m_append(m0, ccmp.ic_trailer, b);
529 }
530 #undef CCMP_ENCRYPT
531 
532 #define	CCMP_DECRYPT(_i, _b, _b0, _pos, _a, _len) do {	\
533 	/* Decrypt, with counter */			\
534 	_b0[14] = (_i >> 8) & 0xff;			\
535 	_b0[15] = _i & 0xff;				\
536 	rijndael_encrypt(&ctx->cc_aes, _b0, _b);	\
537 	xor_block(_pos, _b, _len);			\
538 	/* Authentication */				\
539 	xor_block(_a, _pos, _len);			\
540 	rijndael_encrypt(&ctx->cc_aes, _a, _a);		\
541 } while (0)
542 
543 static int
544 ccmp_decrypt(struct ieee80211_key *key, u_int64_t pn, struct mbuf *m, int hdrlen)
545 {
546 	struct ccmp_ctx *ctx = key->wk_private;
547 	struct ieee80211_frame *wh;
548 	uint8_t aad[2 * AES_BLOCK_LEN];
549 	uint8_t b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN], a[AES_BLOCK_LEN];
550 	uint8_t mic[AES_BLOCK_LEN];
551 	size_t data_len;
552 	int i;
553 	uint8_t *pos;
554 	u_int space;
555 
556 	ctx->cc_ic->ic_stats.is_crypto_ccmp++;
557 
558 	wh = mtod(m, struct ieee80211_frame *);
559 	data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header + ccmp.ic_trailer);
560 	ccmp_init_blocks(&ctx->cc_aes, wh, pn, data_len, b0, aad, a, b);
561 	m_copydata(m, m->m_pkthdr.len - ccmp.ic_trailer, ccmp.ic_trailer, mic);
562 	xor_block(mic, b, ccmp.ic_trailer);
563 
564 	i = 1;
565 	pos = mtod(m, uint8_t *) + hdrlen + ccmp.ic_header;
566 	space = m->m_len - (hdrlen + ccmp.ic_header);
567 	for (;;) {
568 		if (space > data_len)
569 			space = data_len;
570 		while (space >= AES_BLOCK_LEN) {
571 			CCMP_DECRYPT(i, b, b0, pos, a, AES_BLOCK_LEN);
572 			pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
573 			data_len -= AES_BLOCK_LEN;
574 			i++;
575 		}
576 		if (data_len <= 0)		/* no more data */
577 			break;
578 		m = m->m_next;
579 		if (m == NULL) {		/* last buffer */
580 			if (space != 0)		/* short last block */
581 				CCMP_DECRYPT(i, b, b0, pos, a, space);
582 			break;
583 		}
584 		if (space != 0) {
585 			uint8_t *pos_next;
586 			u_int space_next;
587 			u_int len;
588 
589 			/*
590 			 * Block straddles buffers, split references.  We
591 			 * do not handle splits that require >2 buffers
592 			 * since rx'd frames are never badly fragmented
593 			 * because drivers typically recv in clusters.
594 			 */
595 			pos_next = mtod(m, uint8_t *);
596 			len = min(data_len, AES_BLOCK_LEN);
597 			space_next = len > space ? len - space : 0;
598 			KASSERT(m->m_len >= space_next,
599 				("not enough data in following buffer, "
600 				"m_len %u need %u\n", m->m_len, space_next));
601 
602 			xor_block(b+space, pos_next, space_next);
603 			CCMP_DECRYPT(i, b, b0, pos, a, space);
604 			xor_block(pos_next, b+space, space_next);
605 			data_len -= len;
606 			i++;
607 
608 			pos = pos_next + space_next;
609 			space = m->m_len - space_next;
610 		} else {
611 			/*
612 			 * Setup for next buffer.
613 			 */
614 			pos = mtod(m, uint8_t *);
615 			space = m->m_len;
616 		}
617 	}
618 	if (memcmp(mic, a, ccmp.ic_trailer) != 0) {
619 		IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
620 			"[%s] AES-CCM decrypt failed; MIC mismatch\n",
621 			ether_sprintf(wh->i_addr2));
622 		ctx->cc_ic->ic_stats.is_rx_ccmpmic++;
623 		return 0;
624 	}
625 	return 1;
626 }
627 #undef CCMP_DECRYPT
628 
629 /*
630  * Module glue.
631  */
632 static int
633 ccmp_modevent(module_t mod, int type, void *unused)
634 {
635 	switch (type) {
636 	case MOD_LOAD:
637 		ieee80211_crypto_register(&ccmp);
638 		return 0;
639 	case MOD_UNLOAD:
640 		ieee80211_crypto_unregister(&ccmp);
641 		return 0;
642 	}
643 	return EINVAL;
644 }
645 
646 static moduledata_t ccmp_mod = {
647 	"wlan_ccmp",
648 	ccmp_modevent,
649 	0
650 };
651 DECLARE_MODULE(wlan_ccmp, ccmp_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
652 MODULE_VERSION(wlan_ccmp, 1);
653 MODULE_DEPEND(wlan_ccmp, wlan, 1, 1, 1);
654