update madwifi

[linux-2.6/zen-sources.git] / drivers / net / wireless / madwifi / net80211 / ieee80211_crypto_ccmp.c

/*-
 * 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 3734 2008-06-19 16:58:07Z 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
 * its 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>
#include <asm/scatterlist.h>

#include "if_media.h"

#include <net80211/ieee80211_var.h>

#define AES_BLOCK_LEN 16

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
#define crypto_cipher   crypto_tfm
#endif

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, 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;
        int status = 1;

        _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++;
                status = 0;
        }

/* This function crypto_alloc_foo might sleep. Therefore:
 * Context: process */
        if (k->wk_flags & IEEE80211_KEY_SWCRYPT) {
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
                ctx->cc_tfm = crypto_alloc_tfm("aes", 0);
#else
                ctx->cc_tfm = crypto_alloc_cipher("aes", 0,
                                CRYPTO_ALG_ASYNC);
                if (IS_ERR(ctx->cc_tfm))
                        ctx->cc_tfm = NULL;
#endif
        
                if (ctx->cc_tfm == NULL) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
                                        "%s: kernel support for AES "
                                        "cryptography is not available; the "
                                        "module may not be loaded.\n", 
                                        __func__);
                        FREE(ctx, M_DEVBUF);
                        ctx = NULL;
                        vap->iv_stats.is_crypto_nocipher++;
                        status = 0;
                }
        }

        if (!status)
                _MOD_DEC_USE(THIS_MODULE);
        else {
                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)
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
                crypto_free_tfm(ctx->cc_tfm);
#else
                crypto_free_cipher(ctx->cc_tfm);
#endif
        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)
                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_sw)
{
        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 && 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, int force_sw)
{
        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)
{
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,19)
        crypto_cipher_encrypt_one(tfm, dst, src);
#else
        struct scatterlist sg_src;
        struct scatterlist sg_dst;

        sg_src.page = virt_to_page(src);
        sg_src.offset = offset_in_page(src);
        sg_src.length = AES_BLOCK_LEN;

        sg_dst.page = virt_to_page(dst);
        sg_dst.offset = offset_in_page(dst);
        sg_dst.length = AES_BLOCK_LEN;
        crypto_cipher_encrypt(tfm, &sg_dst, &sg_src, AES_BLOCK_LEN);
#endif
}

/*
 * 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_4ADDRESS(wh) \
        ((wh->i_fc[1] & IEEE80211_FC1_DIR_MASK) == IEEE80211_FC1_DIR_DSTODS)
#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 (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
#undef  IS_4ADDRESS
}

#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", 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", 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, (unsigned long long)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);