drivers/qtn/wlan/ieee80211_crypto_ccmp.c - kernel/quantenna - Git at Google

 /*-
  * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * Alternatively, this software may be distributed under the terms of the
  * GNU General Public License ("GPL") version 2 as published by the Free
  * Software Foundation.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * $Id: ieee80211_crypto_ccmp.c 2144 2007-02-21 20:58:48Z proski $
  */

 /*
  * IEEE 802.11i AES-CCMP crypto support.
  *
  * Part of this module is derived from similar code in the Host
  * AP driver. The code is used with the consent of the author and
  * it's license is included below.
  */
 #ifndef AUTOCONF_INCLUDED
 #include <linux/config.h>
 #endif
 #include <linux/version.h>
 #include <linux/module.h>
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
 #include <linux/random.h>
 #include <linux/init.h>

 #include <linux/crypto.h>
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4,7,0)
 #include <linux/scatterlist.h>
 #else
 #include <asm/scatterlist.h>
 #endif

 #include "net80211/if_media.h"

 #include "net80211/ieee80211_var.h"

 #define AES_BLOCK_LEN 16

 struct ccmp_ctx {
 	struct ieee80211vap *cc_vap;	/* for diagnostics + statistics */
 	struct ieee80211com *cc_ic;
 	struct crypto_cipher *cc_tfm;
 };

 static void *ccmp_attach(struct ieee80211vap *, struct ieee80211_key *);
 static void ccmp_detach(struct ieee80211_key *);
 static int ccmp_setkey(struct ieee80211_key *);
 static int ccmp_encap(struct ieee80211_key *, struct sk_buff *, u_int8_t);
 static int ccmp_decap(struct ieee80211_key *, struct sk_buff *, int);
 static int ccmp_enmic(struct ieee80211_key *, struct sk_buff *, int);
 static int ccmp_demic(struct ieee80211_key *, struct sk_buff *, int);

 static const struct ieee80211_cipher ccmp = {
 	.ic_name	= "AES-CCM",
 	.ic_cipher	= IEEE80211_CIPHER_AES_CCM,
 	.ic_header	= IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN +
 			  IEEE80211_WEP_EXTIVLEN,
 	.ic_trailer	= IEEE80211_WEP_MICLEN,
 	.ic_miclen	= 0,
 	.ic_attach	= ccmp_attach,
 	.ic_detach	= ccmp_detach,
 	.ic_setkey	= ccmp_setkey,
 	.ic_encap	= ccmp_encap,
 	.ic_decap	= ccmp_decap,
 	.ic_enmic	= ccmp_enmic,
 	.ic_demic	= ccmp_demic,
 };

 static int ccmp_encrypt(struct ieee80211_key *, struct sk_buff *, int);
 static int ccmp_decrypt(struct ieee80211_key *, u_int64_t, struct sk_buff *, int);

 static void *
 ccmp_attach(struct ieee80211vap *vap, struct ieee80211_key *k)
 {
 	struct ccmp_ctx *ctx;

 	_MOD_INC_USE(THIS_MODULE, return NULL);

 	MALLOC(ctx, struct ccmp_ctx *, sizeof(struct ccmp_ctx),
 		M_DEVBUF, M_NOWAIT | M_ZERO);
 	if (ctx == NULL) {
 		vap->iv_stats.is_crypto_nomem++;
 		_MOD_DEC_USE(THIS_MODULE);
 		return NULL;
 	}

 	ctx->cc_vap = vap;
 	ctx->cc_ic = vap->iv_ic;
 	return ctx;
 }

 static void
 ccmp_detach(struct ieee80211_key *k)
 {
 	struct ccmp_ctx *ctx = k->wk_private;

 	if (ctx->cc_tfm != NULL)
 		crypto_free_cipher(ctx->cc_tfm);
 	FREE(ctx, M_DEVBUF);

 	_MOD_DEC_USE(THIS_MODULE);
 }

 static int
 ccmp_setkey(struct ieee80211_key *k)
 {
 	struct ccmp_ctx *ctx = k->wk_private;

 	if (k->wk_keylen != (128 / NBBY)) {
 		IEEE80211_DPRINTF(ctx->cc_vap, IEEE80211_MSG_CRYPTO,
 			"%s: Invalid key length %u, expecting %u\n",
 			__func__, k->wk_keylen, 128 / NBBY);
 		return 0;
 	}

 	if (k->wk_flags & IEEE80211_KEY_SWCRYPT) {
 		if (ctx->cc_tfm == NULL)
 			ctx->cc_tfm = crypto_alloc_cipher("aes", 0,
 							  CRYPTO_ALG_ASYNC);

 		if (ctx->cc_tfm == NULL) {
 			IEEE80211_DPRINTF(ctx->cc_vap, IEEE80211_MSG_CRYPTO,
 				"%s: Tried to add a software crypto key, but software crypto not available\n",
 				__func__);
 			return 0;
 		}

 		crypto_cipher_setkey(ctx->cc_tfm, k->wk_key, k->wk_keylen);
 	}
 	return 1;
 }

 /*
  * Add privacy headers appropriate for the specified key.
  */
 static int
 ccmp_encap(struct ieee80211_key *k, struct sk_buff *skb, u_int8_t keyid)
 {
 	struct ccmp_ctx *ctx = k->wk_private;
 	struct ieee80211com *ic = ctx->cc_ic;
 	u_int8_t *ivp;
 	int hdrlen;

 	hdrlen = ieee80211_hdrspace(ic, skb->data);

 	/*
 	 * Copy down 802.11 header and add the IV, KeyID, and ExtIV.
 	 */
 	ivp = skb_push(skb, ccmp.ic_header);
 	memmove(ivp, ivp + ccmp.ic_header, hdrlen);
 	ivp += hdrlen;

 	k->wk_keytsc++;		/* XXX wrap at 48 bits */
 	ivp[0] = k->wk_keytsc >> 0;		/* PN0 */
 	ivp[1] = k->wk_keytsc >> 8;		/* PN1 */
 	ivp[2] = 0;				/* Reserved */
 	ivp[3] = keyid | IEEE80211_WEP_EXTIV;	/* KeyID | ExtID */
 	ivp[4] = k->wk_keytsc >> 16;		/* PN2 */
 	ivp[5] = k->wk_keytsc >> 24;		/* PN3 */
 	ivp[6] = k->wk_keytsc >> 32;		/* PN4 */
 	ivp[7] = k->wk_keytsc >> 40;		/* PN5 */

 	/*
 	 * Finally, do software encrypt if neeed.
 	 */
 	if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
 	    !ccmp_encrypt(k, skb, hdrlen))
 		return 0;

 	return 1;
 }

 /*
  * Add MIC to the frame as needed.
  */
 static int
 ccmp_enmic(struct ieee80211_key *k, struct sk_buff *skb, int force)
 {
 	return 1;
 }

 static __inline uint64_t
 READ_6(uint8_t b0, uint8_t b1, uint8_t b2, uint8_t b3, uint8_t b4, uint8_t b5)
 {
 	uint32_t iv32 = (b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24);
 	uint16_t iv16 = (b4 << 0) | (b5 << 8);
 	return (((uint64_t)iv16) << 32) | iv32;
 }

 /*
  * Validate and strip privacy headers (and trailer) for a
  * received frame. The specified key should be correct but
  * is also verified.
  */
 static int
 ccmp_decap(struct ieee80211_key *k, struct sk_buff *skb, int hdrlen)
 {
 	struct ccmp_ctx *ctx = k->wk_private;
 	struct ieee80211vap *vap = ctx->cc_vap;
 	struct ieee80211_frame *wh;
 	uint8_t *ivp;
 	uint64_t pn;
 	u_int8_t tid;

 	/*
 	 * Header should have extended IV and sequence number;
 	 * verify the former and validate the latter.
 	 */
 	wh = (struct ieee80211_frame *)skb->data;
 	ivp = skb->data + hdrlen;
 	if ((ivp[IEEE80211_WEP_IVLEN] & IEEE80211_WEP_EXTIV) == 0) {
 		/*
 		 * No extended IV; discard frame.
 		 */
 		IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
 			"%s", "Missing ExtIV for AES-CCM cipher");
 		vap->iv_stats.is_rx_ccmpformat++;
 		return 0;
 	}
 	tid = 0;
 	if (IEEE80211_QOS_HAS_SEQ(wh))
 		tid = ((struct ieee80211_qosframe *)wh)->i_qos[0] & IEEE80211_QOS_TID;
 	/* NB: assume IEEE80211_WEP_MINLEN covers the extended IV */
 	pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
 	if (pn <= k->wk_keyrsc[tid]) {
 		/*
 		 * Replay violation.
 		 */
 		ieee80211_notify_replay_failure(vap, wh, k, pn);
 		vap->iv_stats.is_rx_ccmpreplay++;
 		return 0;
 	}

 	/*
 	 * Check if the device handled the decrypt in hardware.
 	 * If so we just strip the header; otherwise we need to
 	 * handle the decrypt in software.  Note that for the
 	 * latter we leave the header in place for use in the
 	 * decryption work.
 	 */
 	if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
 	    !ccmp_decrypt(k, pn, skb, hdrlen))
 		return 0;

 	/*
 	 * Copy up 802.11 header and strip crypto bits.
 	 */
 	memmove(skb->data + ccmp.ic_header, skb->data, hdrlen);
 	skb_pull(skb, ccmp.ic_header);
 	while (skb->next != NULL)
 		skb = skb->next;
 	skb_trim(skb, skb->len - ccmp.ic_trailer);

 	/*
 	 * Ok to update rsc now.
 	 */
 	k->wk_keyrsc[tid] = pn;

 	return 1;
 }

 /*
  * Verify and strip MIC from the frame.
  */
 static int
 ccmp_demic(struct ieee80211_key *k, struct sk_buff *skb, int hdrlen)
 {
 	return 1;
 }

 static __inline void
 xor_block(u8 *b, const u8 *a, size_t len)
 {
 	int i;
 	for (i = 0; i < len; i++)
 		b[i] ^= a[i];
 }

 static void
 rijndael_encrypt(struct crypto_cipher *tfm, const void *src, void *dst)
 {
 	crypto_cipher_encrypt_one(tfm, dst, src);
 }

 /*
  * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
  *
  * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation. See README and COPYING for
  * more details.
  *
  * Alternatively, this software may be distributed under the terms of BSD
  * license.
  */

 static void
 ccmp_init_blocks(struct crypto_cipher *tfm, struct ieee80211_frame *wh,
 	u_int64_t pn, size_t dlen,
 	uint8_t b0[AES_BLOCK_LEN], uint8_t aad[2 * AES_BLOCK_LEN],
 	uint8_t auth[AES_BLOCK_LEN], uint8_t s0[AES_BLOCK_LEN])
 {
 #define	IS_QOS_DATA(wh)	IEEE80211_QOS_HAS_SEQ(wh)

 	/* CCM Initial Block:
 	 * Flag (Include authentication header, M=3 (8-octet MIC),
 	 *       L=1 (2-octet Dlen))
 	 * Nonce: 0x00 | A2 | PN
 	 * Dlen */
 	b0[0] = 0x59;
 	/* NB: b0[1] set below */
 	IEEE80211_ADDR_COPY(b0 + 2, wh->i_addr2);
 	b0[8] = pn >> 40;
 	b0[9] = pn >> 32;
 	b0[10] = pn >> 24;
 	b0[11] = pn >> 16;
 	b0[12] = pn >> 8;
 	b0[13] = pn >> 0;
 	b0[14] = (dlen >> 8) & 0xff;
 	b0[15] = dlen & 0xff;

 	/* AAD:
 	 * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
 	 * A1 | A2 | A3
 	 * SC with bits 4..15 (seq#) masked to zero
 	 * A4 (if present)
 	 * QC (if present)
 	 */
 	aad[0] = 0;	/* AAD length >> 8 */
 	/* NB: aad[1] set below */
 	aad[2] = wh->i_fc[0] & 0x8f;	/* XXX magic #s */
 	aad[3] = wh->i_fc[1] & 0xc7;	/* XXX magic #s */
 	/* NB: we know 3 addresses are contiguous */
 	memcpy(aad + 4, wh->i_addr1, 3 * IEEE80211_ADDR_LEN);
 	aad[22] = wh->i_seq[0] & IEEE80211_SEQ_FRAG_MASK;
 	aad[23] = 0; /* all bits masked */
 	/*
 	 * Construct variable-length portion of AAD based
 	 * on whether this is a 4-address frame/QOS frame.
 	 * We always zero-pad to 32 bytes before running it
 	 * through the cipher.
 	 *
 	 * We also fill in the priority bits of the CCM
 	 * initial block as we know whether or not we have
 	 * a QOS frame.
 	 */
 	if (IEEE80211_IS_4ADDRESS(wh)) {
 		IEEE80211_ADDR_COPY(aad + 24,
 			((struct ieee80211_frame_addr4 *)wh)->i_addr4);
 		if (IS_QOS_DATA(wh)) {
 			struct ieee80211_qosframe_addr4 *qwh4 =
 				(struct ieee80211_qosframe_addr4 *) wh;
 			aad[30] = qwh4->i_qos[0] & 0x0f;/* just priority bits */
 			aad[31] = 0;
 			b0[1] = aad[30];
 			aad[1] = 22 + IEEE80211_ADDR_LEN + 2;
 		} else {
 			*(u_int16_t *)&aad[30] = 0;
 			b0[1] = 0;
 			aad[1] = 22 + IEEE80211_ADDR_LEN;
 		}
 	} else {
 		if (IS_QOS_DATA(wh)) {
 			struct ieee80211_qosframe *qwh =
 				(struct ieee80211_qosframe*) wh;
 			aad[24] = qwh->i_qos[0] & 0x0f;	/* just priority bits */
 			aad[25] = 0;
 			b0[1] = aad[24];
 			aad[1] = 22 + 2;
 		} else {
 			*(u_int16_t *)&aad[24] = 0;
 			b0[1] = 0;
 			aad[1] = 22;
 		}
 		*(u_int16_t *)&aad[26] = 0;
 		*(u_int32_t *)&aad[28] = 0;
 	}

 	/* Start with the first block and AAD */
 	rijndael_encrypt(tfm, b0, auth);
 	xor_block(auth, aad, AES_BLOCK_LEN);
 	rijndael_encrypt(tfm, auth, auth);
 	xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
 	rijndael_encrypt(tfm, auth, auth);
 	b0[0] &= 0x07;
 	b0[14] = b0[15] = 0;
 	rijndael_encrypt(tfm, b0, s0);
 #undef	IS_QOS_DATA
 }

 #define	CCMP_ENCRYPT(_i, _b, _b0, _pos, _e, _len) do {	\
 	/* Authentication */				\
 	xor_block(_b, _pos, _len);			\
 	rijndael_encrypt(ctx->cc_tfm, _b, _b);		\
 	/* Encryption, with counter */			\
 	_b0[14] = (_i >> 8) & 0xff;			\
 	_b0[15] = _i & 0xff;				\
 	rijndael_encrypt(ctx->cc_tfm, _b0, _e);		\
 	xor_block(_pos, _e, _len);			\
 } while (0)

 static int
 ccmp_encrypt(struct ieee80211_key *key, struct sk_buff *skb0, int hdrlen)
 {
 	struct ccmp_ctx *ctx = key->wk_private;
 	struct ieee80211_frame *wh = (struct ieee80211_frame *) skb0->data;
 	struct sk_buff *skb;
 	int data_len, i;
 	uint8_t aad[2 * AES_BLOCK_LEN], b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN];
 	uint8_t e[AES_BLOCK_LEN], s0[AES_BLOCK_LEN];
 	uint8_t *mic, *pos;
 	u_int space;

 	ctx->cc_vap->iv_stats.is_crypto_ccmp++;

 	skb = skb0;
 	data_len = skb->len;
 	while (skb->next != NULL) {
 		skb = skb->next;
 		data_len += skb->len;
 	}
 	data_len -= hdrlen + ccmp.ic_header;
 	if (skb_tailroom(skb) < ccmp.ic_trailer) {
 		/* NB: should not happen */
 		IEEE80211_NOTE_MAC(ctx->cc_vap, IEEE80211_MSG_CRYPTO,
 			wh->i_addr1, "No room for %s MIC, tailroom %u",
 			ccmp.ic_name, skb_tailroom(skb));
 		/* XXX statistic */
 		return 0;
 	}
 	ccmp_init_blocks(ctx->cc_tfm, wh, key->wk_keytsc,
 		data_len, b0, aad, b, s0);

 	i = 1;
 	skb = skb0;
 	pos = skb->data + hdrlen + ccmp.ic_header;
 	/* NB: assumes header is entirely in first skbuf */
 	space = skb->len - (hdrlen + ccmp.ic_header);
 	for (;;) {
 		if (space > data_len)
 			space = data_len;
 		/*
 		 * Do full blocks.
 		 */
 		while (space >= AES_BLOCK_LEN) {
 			CCMP_ENCRYPT(i, b, b0, pos, e, AES_BLOCK_LEN);
 			pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
 			data_len -= AES_BLOCK_LEN;
 			i++;
 		}
 		if (data_len <= 0)		/* no more data */
 			break;
 		if (skb->next == NULL) {	/* last buffer */
 			if (space != 0) {
 				/*
 				 * Short last block.
 				 */
 				CCMP_ENCRYPT(i, b, b0, pos, e, space);
 			}
 			break;
 		}
 		skb = skb->next;
 		if (space != 0) {
 			uint8_t *pos_next;
 			u_int space_next;
 			u_int len;

 			/*
 			 * Block straddles buffers, split references.  We
 			 * do not handle splits that require >2 buffers.
 			 */
 			pos_next = skb->data;
 			len = min(data_len, AES_BLOCK_LEN);
 			space_next = len > space ? len - space : 0;
 			KASSERT(skb->len >= space_next,
 				("not enough data in following buffer, "
 				"skb len %u need %u\n", skb->len, space_next));

 			xor_block(b + space, pos_next, space_next);
 			CCMP_ENCRYPT(i, b, b0, pos, e, space);
 			xor_block(pos_next, e + space, space_next);
 			data_len -= len;
 			/* XXX could check for data_len <= 0 */
 			i++;

 			pos = pos_next + space_next;
 			space = skb->len - space_next;
 		} else {
 			/*
 			 * Setup for next buffer.
 			 */
 			pos = skb->data;
 			space = skb->len;
 		}
 	}
 	/* tack on MIC */
 	mic = skb_put(skb, ccmp.ic_trailer);
 	for (i = 0; i < ccmp.ic_trailer; i++)
 		mic[i] = b[i] ^ s0[i];
 	return 1;
 }
 #undef CCMP_ENCRYPT

 #define	CCMP_DECRYPT(_i, _b, _b0, _pos, _a, _len) do {	\
 	/* Decrypt, with counter */			\
 	_b0[14] = (_i >> 8) & 0xff;			\
 	_b0[15] = _i & 0xff;				\
 	rijndael_encrypt(ctx->cc_tfm, _b0, _b);		\
 	xor_block(_pos, _b, _len);			\
 	/* Authentication */				\
 	xor_block(_a, _pos, _len);			\
 	rijndael_encrypt(ctx->cc_tfm, _a, _a);		\
 } while (0)

 static int
 ccmp_decrypt(struct ieee80211_key *key, u_int64_t pn, struct sk_buff *skb0, int hdrlen)
 {
 	struct ccmp_ctx *ctx = key->wk_private;
 	struct ieee80211_frame *wh = (struct ieee80211_frame *) skb0->data;
 	struct sk_buff *skb;
 	uint8_t aad[2 * AES_BLOCK_LEN];
 	uint8_t b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN], a[AES_BLOCK_LEN];
 	size_t data_len;
 	int i;
 	uint8_t *pos, *mic;
 	u_int space;

 	ctx->cc_vap->iv_stats.is_crypto_ccmp++;

 	skb = skb0;
 	data_len = skb->len;
 	while (skb->next != NULL) {
 		skb = skb->next;
 		data_len += skb->len;
 	}
 	data_len -= hdrlen + ccmp.ic_header + ccmp.ic_trailer;
 	/* NB: skb left pointing at last in chain */
 	ccmp_init_blocks(ctx->cc_tfm, wh, pn, data_len, b0, aad, a, b);
 	/* NB: this is the last in the chain */
 	/* XXX assert skb->len >= ccmp.ic_trailer */
 	mic = skb->data + skb->len - ccmp.ic_trailer;
 	xor_block(mic, b, ccmp.ic_trailer);

 	i = 1;
 	skb = skb0;
 	pos = skb->data + hdrlen + ccmp.ic_header;
 	space = skb->len - (hdrlen + ccmp.ic_header);
 	for (;;) {
 		if (space > data_len)
 			space = data_len;
 		while (space >= AES_BLOCK_LEN) {
 			CCMP_DECRYPT(i, b, b0, pos, a, AES_BLOCK_LEN);
 			pos += AES_BLOCK_LEN;
 			space -= AES_BLOCK_LEN;
 			data_len -= AES_BLOCK_LEN;
 			i++;
 		}
 		if (data_len <= 0)		/* no more data */
 			break;
 		skb = skb->next;
 		if (skb == NULL) {		/* last buffer */
 			if (space != 0)		/* short last block */
 				CCMP_DECRYPT(i, b, b0, pos, a, space);
 			break;
 		}
 		if (space != 0) {
 			uint8_t *pos_next;
 			u_int space_next;
 			u_int len;

 			/*
 			 * Block straddles buffers, split references.  We
 			 * do not handle splits that require >2 buffers.
 			 */
 			pos_next = skb->data;
 			len = min(data_len, (size_t) AES_BLOCK_LEN);
 			space_next = len > space ? len - space : 0;
 			KASSERT(skb->len >= space_next,
 				("not enough data in following buffer, "
 				"skb len %u need %u\n", skb->len, space_next));

 			xor_block(b+space, pos_next, space_next);
 			CCMP_DECRYPT(i, b, b0, pos, a, space);
 			xor_block(pos_next, b+space, space_next);
 			data_len -= len;
 			i++;

 			pos = pos_next + space_next;
 			space = skb->len - space_next;
 		} else {
 			/*
 			 * Setup for next buffer.
 			 */
 			pos = skb->data;
 			space = skb->len;
 		}
 	}

 	if (memcmp(mic, a, ccmp.ic_trailer) != 0) {
 		IEEE80211_NOTE_MAC(ctx->cc_vap, IEEE80211_MSG_CRYPTO,
 			wh->i_addr2,
 			"AES-CCM decrypt failed; MIC mismatch (keyix %u, rsc %llu)",
 			key->wk_keyix, pn);
 		ctx->cc_vap->iv_stats.is_rx_ccmpmic++;
 		return 0;
 	}
 	return 1;
 }
 #undef CCMP_DECRYPT

 /*
  * Module glue.
  */

 MODULE_AUTHOR("Errno Consulting, Sam Leffler");
 MODULE_DESCRIPTION("802.11 wireless support: AES-CCM cipher");
 #ifdef MODULE_LICENSE
 MODULE_LICENSE("Dual BSD/GPL");
 #endif

 static int __init
 init_crypto_ccmp(void)
 {
 	ieee80211_crypto_register(&ccmp);
 	return 0;
 }
 module_init(init_crypto_ccmp);

 static void __exit
 exit_crypto_ccmp(void)
 {
 	ieee80211_crypto_unregister(&ccmp);
 }
 module_exit(exit_crypto_ccmp);
	/*-
	* Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. The name of the author may not be used to endorse or promote products
	* derived from this software without specific prior written permission.
	*
	* Alternatively, this software may be distributed under the terms of the
	* GNU General Public License ("GPL") version 2 as published by the Free
	* Software Foundation.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	* $Id: ieee80211_crypto_ccmp.c 2144 2007-02-21 20:58:48Z proski $
	*/

	/*
	* IEEE 802.11i AES-CCMP crypto support.
	*
	* Part of this module is derived from similar code in the Host
	* AP driver. The code is used with the consent of the author and
	* it's license is included below.
	*/
	#ifndef AUTOCONF_INCLUDED
	#include <linux/config.h>
	#endif
	#include <linux/version.h>
	#include <linux/module.h>
	#include <linux/skbuff.h>
	#include <linux/netdevice.h>
	#include <linux/random.h>
	#include <linux/init.h>

	#include <linux/crypto.h>
	#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,7,0)
	#include <linux/scatterlist.h>
	#else
	#include <asm/scatterlist.h>
	#endif

	#include "net80211/if_media.h"

	#include "net80211/ieee80211_var.h"

	#define AES_BLOCK_LEN 16

	struct ccmp_ctx {
	struct ieee80211vap cc_vap; / for diagnostics + statistics */
	struct ieee80211com *cc_ic;
	struct crypto_cipher *cc_tfm;
	};

	static void ccmp_attach(struct ieee80211vap , struct ieee80211_key *);
	static void ccmp_detach(struct ieee80211_key *);
	static int ccmp_setkey(struct ieee80211_key *);
	static int ccmp_encap(struct ieee80211_key , struct sk_buff , u_int8_t);
	static int ccmp_decap(struct ieee80211_key , struct sk_buff , int);
	static int ccmp_enmic(struct ieee80211_key , struct sk_buff , int);
	static int ccmp_demic(struct ieee80211_key , struct sk_buff , int);

	static const struct ieee80211_cipher ccmp = {
	.ic_name = "AES-CCM",
	.ic_cipher = IEEE80211_CIPHER_AES_CCM,
	.ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN +
	IEEE80211_WEP_EXTIVLEN,
	.ic_trailer = IEEE80211_WEP_MICLEN,
	.ic_miclen = 0,
	.ic_attach = ccmp_attach,
	.ic_detach = ccmp_detach,
	.ic_setkey = ccmp_setkey,
	.ic_encap = ccmp_encap,
	.ic_decap = ccmp_decap,
	.ic_enmic = ccmp_enmic,
	.ic_demic = ccmp_demic,
	};

	static int ccmp_encrypt(struct ieee80211_key , struct sk_buff , int);
	static int ccmp_decrypt(struct ieee80211_key , u_int64_t, struct sk_buff , int);

	static void *
	ccmp_attach(struct ieee80211vap vap, struct ieee80211_key k)
	{
	struct ccmp_ctx *ctx;

	_MOD_INC_USE(THIS_MODULE, return NULL);

	MALLOC(ctx, struct ccmp_ctx *, sizeof(struct ccmp_ctx),
	M_DEVBUF, M_NOWAIT \| M_ZERO);
	if (ctx == NULL) {
	vap->iv_stats.is_crypto_nomem++;
	_MOD_DEC_USE(THIS_MODULE);
	return NULL;
	}

	ctx->cc_vap = vap;
	ctx->cc_ic = vap->iv_ic;
	return ctx;
	}

	static void
	ccmp_detach(struct ieee80211_key *k)
	{
	struct ccmp_ctx *ctx = k->wk_private;

	if (ctx->cc_tfm != NULL)
	crypto_free_cipher(ctx->cc_tfm);
	FREE(ctx, M_DEVBUF);

	_MOD_DEC_USE(THIS_MODULE);
	}

	static int
	ccmp_setkey(struct ieee80211_key *k)
	{
	struct ccmp_ctx *ctx = k->wk_private;

	if (k->wk_keylen != (128 / NBBY)) {
	IEEE80211_DPRINTF(ctx->cc_vap, IEEE80211_MSG_CRYPTO,
	"%s: Invalid key length %u, expecting %u\n",
	__func__, k->wk_keylen, 128 / NBBY);
	return 0;
	}

	if (k->wk_flags & IEEE80211_KEY_SWCRYPT) {
	if (ctx->cc_tfm == NULL)
	ctx->cc_tfm = crypto_alloc_cipher("aes", 0,
	CRYPTO_ALG_ASYNC);

	if (ctx->cc_tfm == NULL) {
	IEEE80211_DPRINTF(ctx->cc_vap, IEEE80211_MSG_CRYPTO,
	"%s: Tried to add a software crypto key, but software crypto not available\n",
	__func__);
	return 0;
	}

	crypto_cipher_setkey(ctx->cc_tfm, k->wk_key, k->wk_keylen);
	}
	return 1;
	}

	/*
	* Add privacy headers appropriate for the specified key.
	*/
	static int
	ccmp_encap(struct ieee80211_key k, struct sk_buff skb, u_int8_t keyid)
	{
	struct ccmp_ctx *ctx = k->wk_private;
	struct ieee80211com *ic = ctx->cc_ic;
	u_int8_t *ivp;
	int hdrlen;

	hdrlen = ieee80211_hdrspace(ic, skb->data);

	/*
	* Copy down 802.11 header and add the IV, KeyID, and ExtIV.
	*/
	ivp = skb_push(skb, ccmp.ic_header);
	memmove(ivp, ivp + ccmp.ic_header, hdrlen);
	ivp += hdrlen;

	k->wk_keytsc++; /* XXX wrap at 48 bits */
	ivp[0] = k->wk_keytsc >> 0; /* PN0 */
	ivp[1] = k->wk_keytsc >> 8; /* PN1 */
	ivp[2] = 0; /* Reserved */
	ivp[3] = keyid \| IEEE80211_WEP_EXTIV; /* KeyID \| ExtID */
	ivp[4] = k->wk_keytsc >> 16; /* PN2 */
	ivp[5] = k->wk_keytsc >> 24; /* PN3 */
	ivp[6] = k->wk_keytsc >> 32; /* PN4 */
	ivp[7] = k->wk_keytsc >> 40; /* PN5 */

	/*
	* Finally, do software encrypt if neeed.
	*/
	if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
	!ccmp_encrypt(k, skb, hdrlen))
	return 0;

	return 1;
	}

	/*
	* Add MIC to the frame as needed.
	*/
	static int
	ccmp_enmic(struct ieee80211_key k, struct sk_buff skb, int force)
	{
	return 1;
	}

	static __inline uint64_t
	READ_6(uint8_t b0, uint8_t b1, uint8_t b2, uint8_t b3, uint8_t b4, uint8_t b5)
	{
	uint32_t iv32 = (b0 << 0) \| (b1 << 8) \| (b2 << 16) \| (b3 << 24);
	uint16_t iv16 = (b4 << 0) \| (b5 << 8);
	return (((uint64_t)iv16) << 32) \| iv32;
	}

	/*
	* Validate and strip privacy headers (and trailer) for a
	* received frame. The specified key should be correct but
	* is also verified.
	*/
	static int
	ccmp_decap(struct ieee80211_key k, struct sk_buff skb, int hdrlen)
	{
	struct ccmp_ctx *ctx = k->wk_private;
	struct ieee80211vap *vap = ctx->cc_vap;
	struct ieee80211_frame *wh;
	uint8_t *ivp;
	uint64_t pn;
	u_int8_t tid;

	/*
	* Header should have extended IV and sequence number;
	* verify the former and validate the latter.
	*/
	wh = (struct ieee80211_frame *)skb->data;
	ivp = skb->data + hdrlen;
	if ((ivp[IEEE80211_WEP_IVLEN] & IEEE80211_WEP_EXTIV) == 0) {
	/*
	* No extended IV; discard frame.
	*/
	IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2,
	"%s", "Missing ExtIV for AES-CCM cipher");
	vap->iv_stats.is_rx_ccmpformat++;
	return 0;
	}
	tid = 0;
	if (IEEE80211_QOS_HAS_SEQ(wh))
	tid = ((struct ieee80211_qosframe *)wh)->i_qos[0] & IEEE80211_QOS_TID;
	/* NB: assume IEEE80211_WEP_MINLEN covers the extended IV */
	pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
	if (pn <= k->wk_keyrsc[tid]) {
	/*
	* Replay violation.
	*/
	ieee80211_notify_replay_failure(vap, wh, k, pn);
	vap->iv_stats.is_rx_ccmpreplay++;
	return 0;
	}

	/*
	* Check if the device handled the decrypt in hardware.
	* If so we just strip the header; otherwise we need to
	* handle the decrypt in software. Note that for the
	* latter we leave the header in place for use in the
	* decryption work.
	*/
	if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
	!ccmp_decrypt(k, pn, skb, hdrlen))
	return 0;

	/*
	* Copy up 802.11 header and strip crypto bits.
	*/
	memmove(skb->data + ccmp.ic_header, skb->data, hdrlen);
	skb_pull(skb, ccmp.ic_header);
	while (skb->next != NULL)
	skb = skb->next;
	skb_trim(skb, skb->len - ccmp.ic_trailer);

	/*
	* Ok to update rsc now.
	*/
	k->wk_keyrsc[tid] = pn;

	return 1;
	}

	/*
	* Verify and strip MIC from the frame.
	*/
	static int
	ccmp_demic(struct ieee80211_key k, struct sk_buff skb, int hdrlen)
	{
	return 1;
	}

	static __inline void
	xor_block(u8 b, const u8 a, size_t len)
	{
	int i;
	for (i = 0; i < len; i++)
	b[i] ^= a[i];
	}

	static void
	rijndael_encrypt(struct crypto_cipher tfm, const void src, void *dst)
	{
	crypto_cipher_encrypt_one(tfm, dst, src);
	}

	/*
	* Host AP crypt: host-based CCMP encryption implementation for Host AP driver
	*
	* Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation. See README and COPYING for
	* more details.
	*
	* Alternatively, this software may be distributed under the terms of BSD
	* license.
	*/

	static void
	ccmp_init_blocks(struct crypto_cipher tfm, struct ieee80211_frame wh,
	u_int64_t pn, size_t dlen,
	uint8_t b0[AES_BLOCK_LEN], uint8_t aad[2 * AES_BLOCK_LEN],
	uint8_t auth[AES_BLOCK_LEN], uint8_t s0[AES_BLOCK_LEN])
	{
	#define IS_QOS_DATA(wh) IEEE80211_QOS_HAS_SEQ(wh)

	/* CCM Initial Block:
	* Flag (Include authentication header, M=3 (8-octet MIC),
	* L=1 (2-octet Dlen))
	* Nonce: 0x00 \| A2 \| PN
	* Dlen */
	b0[0] = 0x59;
	/* NB: b0[1] set below */
	IEEE80211_ADDR_COPY(b0 + 2, wh->i_addr2);
	b0[8] = pn >> 40;
	b0[9] = pn >> 32;
	b0[10] = pn >> 24;
	b0[11] = pn >> 16;
	b0[12] = pn >> 8;
	b0[13] = pn >> 0;
	b0[14] = (dlen >> 8) & 0xff;
	b0[15] = dlen & 0xff;

	/* AAD:
	* FC with bits 4..6 and 11..13 masked to zero; 14 is always one
	* A1 \| A2 \| A3
	* SC with bits 4..15 (seq#) masked to zero
	* A4 (if present)
	* QC (if present)
	*/
	aad[0] = 0; /* AAD length >> 8 */
	/* NB: aad[1] set below */
	aad[2] = wh->i_fc[0] & 0x8f; /* XXX magic #s */
	aad[3] = wh->i_fc[1] & 0xc7; /* XXX magic #s */
	/* NB: we know 3 addresses are contiguous */
	memcpy(aad + 4, wh->i_addr1, 3 * IEEE80211_ADDR_LEN);
	aad[22] = wh->i_seq[0] & IEEE80211_SEQ_FRAG_MASK;
	aad[23] = 0; /* all bits masked */
	/*
	* Construct variable-length portion of AAD based
	* on whether this is a 4-address frame/QOS frame.
	* We always zero-pad to 32 bytes before running it
	* through the cipher.
	*
	* We also fill in the priority bits of the CCM
	* initial block as we know whether or not we have
	* a QOS frame.
	*/
	if (IEEE80211_IS_4ADDRESS(wh)) {
	IEEE80211_ADDR_COPY(aad + 24,
	((struct ieee80211_frame_addr4 *)wh)->i_addr4);
	if (IS_QOS_DATA(wh)) {
	struct ieee80211_qosframe_addr4 *qwh4 =
	(struct ieee80211_qosframe_addr4 *) wh;
	aad[30] = qwh4->i_qos[0] & 0x0f;/* just priority bits */
	aad[31] = 0;
	b0[1] = aad[30];
	aad[1] = 22 + IEEE80211_ADDR_LEN + 2;
	} else {
	(u_int16_t )&aad[30] = 0;
	b0[1] = 0;
	aad[1] = 22 + IEEE80211_ADDR_LEN;
	}
	} else {
	if (IS_QOS_DATA(wh)) {
	struct ieee80211_qosframe *qwh =
	(struct ieee80211_qosframe*) wh;
	aad[24] = qwh->i_qos[0] & 0x0f; /* just priority bits */
	aad[25] = 0;
	b0[1] = aad[24];
	aad[1] = 22 + 2;
	} else {
	(u_int16_t )&aad[24] = 0;
	b0[1] = 0;
	aad[1] = 22;
	}
	(u_int16_t )&aad[26] = 0;
	(u_int32_t )&aad[28] = 0;
	}

	/* Start with the first block and AAD */
	rijndael_encrypt(tfm, b0, auth);
	xor_block(auth, aad, AES_BLOCK_LEN);
	rijndael_encrypt(tfm, auth, auth);
	xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
	rijndael_encrypt(tfm, auth, auth);
	b0[0] &= 0x07;
	b0[14] = b0[15] = 0;
	rijndael_encrypt(tfm, b0, s0);
	#undef IS_QOS_DATA
	}

	#define CCMP_ENCRYPT(_i, _b, _b0, _pos, _e, _len) do { \
	/* Authentication */ \
	xor_block(_b, _pos, _len); \
	rijndael_encrypt(ctx->cc_tfm, _b, _b); \
	/* Encryption, with counter */ \
	_b0[14] = (_i >> 8) & 0xff; \
	_b0[15] = _i & 0xff; \
	rijndael_encrypt(ctx->cc_tfm, _b0, _e); \
	xor_block(_pos, _e, _len); \
	} while (0)

	static int
	ccmp_encrypt(struct ieee80211_key key, struct sk_buff skb0, int hdrlen)
	{
	struct ccmp_ctx *ctx = key->wk_private;
	struct ieee80211_frame wh = (struct ieee80211_frame ) skb0->data;
	struct sk_buff *skb;
	int data_len, i;
	uint8_t aad[2 * AES_BLOCK_LEN], b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN];
	uint8_t e[AES_BLOCK_LEN], s0[AES_BLOCK_LEN];
	uint8_t mic, pos;
	u_int space;

	ctx->cc_vap->iv_stats.is_crypto_ccmp++;

	skb = skb0;
	data_len = skb->len;
	while (skb->next != NULL) {
	skb = skb->next;
	data_len += skb->len;
	}
	data_len -= hdrlen + ccmp.ic_header;
	if (skb_tailroom(skb) < ccmp.ic_trailer) {
	/* NB: should not happen */
	IEEE80211_NOTE_MAC(ctx->cc_vap, IEEE80211_MSG_CRYPTO,
	wh->i_addr1, "No room for %s MIC, tailroom %u",
	ccmp.ic_name, skb_tailroom(skb));
	/* XXX statistic */
	return 0;
	}
	ccmp_init_blocks(ctx->cc_tfm, wh, key->wk_keytsc,
	data_len, b0, aad, b, s0);

	i = 1;
	skb = skb0;
	pos = skb->data + hdrlen + ccmp.ic_header;
	/* NB: assumes header is entirely in first skbuf */
	space = skb->len - (hdrlen + ccmp.ic_header);
	for (;;) {
	if (space > data_len)
	space = data_len;
	/*
	* Do full blocks.
	*/
	while (space >= AES_BLOCK_LEN) {
	CCMP_ENCRYPT(i, b, b0, pos, e, AES_BLOCK_LEN);
	pos += AES_BLOCK_LEN, space -= AES_BLOCK_LEN;
	data_len -= AES_BLOCK_LEN;
	i++;
	}
	if (data_len <= 0) /* no more data */
	break;
	if (skb->next == NULL) { /* last buffer */
	if (space != 0) {
	/*
	* Short last block.
	*/
	CCMP_ENCRYPT(i, b, b0, pos, e, space);
	}
	break;
	}
	skb = skb->next;
	if (space != 0) {
	uint8_t *pos_next;
	u_int space_next;
	u_int len;

	/*
	* Block straddles buffers, split references. We
	* do not handle splits that require >2 buffers.
	*/
	pos_next = skb->data;
	len = min(data_len, AES_BLOCK_LEN);
	space_next = len > space ? len - space : 0;
	KASSERT(skb->len >= space_next,
	("not enough data in following buffer, "
	"skb len %u need %u\n", skb->len, space_next));

	xor_block(b + space, pos_next, space_next);
	CCMP_ENCRYPT(i, b, b0, pos, e, space);
	xor_block(pos_next, e + space, space_next);
	data_len -= len;
	/* XXX could check for data_len <= 0 */
	i++;

	pos = pos_next + space_next;
	space = skb->len - space_next;
	} else {
	/*
	* Setup for next buffer.
	*/
	pos = skb->data;
	space = skb->len;
	}
	}
	/* tack on MIC */
	mic = skb_put(skb, ccmp.ic_trailer);
	for (i = 0; i < ccmp.ic_trailer; i++)
	mic[i] = b[i] ^ s0[i];
	return 1;
	}
	#undef CCMP_ENCRYPT

	#define CCMP_DECRYPT(_i, _b, _b0, _pos, _a, _len) do { \
	/* Decrypt, with counter */ \
	_b0[14] = (_i >> 8) & 0xff; \
	_b0[15] = _i & 0xff; \
	rijndael_encrypt(ctx->cc_tfm, _b0, _b); \
	xor_block(_pos, _b, _len); \
	/* Authentication */ \
	xor_block(_a, _pos, _len); \
	rijndael_encrypt(ctx->cc_tfm, _a, _a); \
	} while (0)

	static int
	ccmp_decrypt(struct ieee80211_key key, u_int64_t pn, struct sk_buff skb0, int hdrlen)
	{
	struct ccmp_ctx *ctx = key->wk_private;
	struct ieee80211_frame wh = (struct ieee80211_frame ) skb0->data;
	struct sk_buff *skb;
	uint8_t aad[2 * AES_BLOCK_LEN];
	uint8_t b0[AES_BLOCK_LEN], b[AES_BLOCK_LEN], a[AES_BLOCK_LEN];
	size_t data_len;
	int i;
	uint8_t pos, mic;
	u_int space;

	ctx->cc_vap->iv_stats.is_crypto_ccmp++;

	skb = skb0;
	data_len = skb->len;
	while (skb->next != NULL) {
	skb = skb->next;
	data_len += skb->len;
	}
	data_len -= hdrlen + ccmp.ic_header + ccmp.ic_trailer;
	/* NB: skb left pointing at last in chain */
	ccmp_init_blocks(ctx->cc_tfm, wh, pn, data_len, b0, aad, a, b);
	/* NB: this is the last in the chain */
	/* XXX assert skb->len >= ccmp.ic_trailer */
	mic = skb->data + skb->len - ccmp.ic_trailer;
	xor_block(mic, b, ccmp.ic_trailer);

	i = 1;
	skb = skb0;
	pos = skb->data + hdrlen + ccmp.ic_header;
	space = skb->len - (hdrlen + ccmp.ic_header);
	for (;;) {
	if (space > data_len)
	space = data_len;
	while (space >= AES_BLOCK_LEN) {
	CCMP_DECRYPT(i, b, b0, pos, a, AES_BLOCK_LEN);
	pos += AES_BLOCK_LEN;
	space -= AES_BLOCK_LEN;
	data_len -= AES_BLOCK_LEN;
	i++;
	}
	if (data_len <= 0) /* no more data */
	break;
	skb = skb->next;
	if (skb == NULL) { /* last buffer */
	if (space != 0) /* short last block */
	CCMP_DECRYPT(i, b, b0, pos, a, space);
	break;
	}
	if (space != 0) {
	uint8_t *pos_next;
	u_int space_next;
	u_int len;

	/*
	* Block straddles buffers, split references. We
	* do not handle splits that require >2 buffers.
	*/
	pos_next = skb->data;
	len = min(data_len, (size_t) AES_BLOCK_LEN);
	space_next = len > space ? len - space : 0;
	KASSERT(skb->len >= space_next,
	("not enough data in following buffer, "
	"skb len %u need %u\n", skb->len, space_next));

	xor_block(b+space, pos_next, space_next);
	CCMP_DECRYPT(i, b, b0, pos, a, space);
	xor_block(pos_next, b+space, space_next);
	data_len -= len;
	i++;

	pos = pos_next + space_next;
	space = skb->len - space_next;
	} else {
	/*
	* Setup for next buffer.
	*/
	pos = skb->data;
	space = skb->len;
	}
	}

	if (memcmp(mic, a, ccmp.ic_trailer) != 0) {
	IEEE80211_NOTE_MAC(ctx->cc_vap, IEEE80211_MSG_CRYPTO,
	wh->i_addr2,
	"AES-CCM decrypt failed; MIC mismatch (keyix %u, rsc %llu)",
	key->wk_keyix, pn);
	ctx->cc_vap->iv_stats.is_rx_ccmpmic++;
	return 0;
	}
	return 1;
	}
	#undef CCMP_DECRYPT

	/*
	* Module glue.
	*/

	MODULE_AUTHOR("Errno Consulting, Sam Leffler");
	MODULE_DESCRIPTION("802.11 wireless support: AES-CCM cipher");
	#ifdef MODULE_LICENSE
	MODULE_LICENSE("Dual BSD/GPL");
	#endif

	static int __init
	init_crypto_ccmp(void)
	{
	ieee80211_crypto_register(&ccmp);
	return 0;
	}
	module_init(init_crypto_ccmp);

	static void __exit
	exit_crypto_ccmp(void)
	{
	ieee80211_crypto_unregister(&ccmp);
	}
	module_exit(exit_crypto_ccmp);