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ieee80211_crypto_ccmp.c revision 1.1.1.2
      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: src/sys/net80211/ieee80211_crypto_ccmp.c,v 1.7 2005/07/11 03:06:23 sam Exp $");
     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 (at) 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