io/net80211/net80211_crypto_tkip.c

	net80211_crypto_tkip.c revision a399b7655a1d835aa8606c2b29e4e777baac8635
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2001 Atsushi Onoe
 * 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.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * IEEE 802.11i TKIP crypto support.
 */
#include <sys/byteorder.h>
#include <sys/crypto/common.h>
#include <sys/crypto/api.h>
#include <sys/crc32.h>
#include <sys/random.h>
#include "net80211_impl.h"

static void *tkip_attach(struct ieee80211com *, struct ieee80211_key *);
static void tkip_detach(struct ieee80211_key *);
static int tkip_setkey(struct ieee80211_key *);
static int tkip_encap(struct ieee80211_key *, mblk_t *, uint8_t);
static int tkip_decap(struct ieee80211_key *, mblk_t *, int);
static int tkip_enmic(struct ieee80211_key *, mblk_t *, int);
static int tkip_demic(struct ieee80211_key *, mblk_t *, int);

const struct ieee80211_cipher tkip  = {
    "TKIP",
    IEEE80211_CIPHER_TKIP,
    IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN +
        IEEE80211_WEP_EXTIVLEN,
    IEEE80211_WEP_CRCLEN,
    IEEE80211_WEP_MICLEN,
    tkip_attach,
    tkip_detach,
    tkip_setkey,
    tkip_encap,
    tkip_decap,
    tkip_enmic,
    tkip_demic,
};

struct tkip_ctx {
    struct ieee80211com *tc_ic;     /* for diagnostics */
    uint16_t        tx_ttak[5];
    int         tx_phase1_done;
    uint8_t         tx_rc4key[16];
    uint16_t        rx_ttak[5];
    int         rx_phase1_done;
    uint8_t         rx_rc4key[16];
    uint64_t        rx_rsc;     /* held until MIC verified */
};

/* ARGSUSED */
static void *
tkip_attach(struct ieee80211com *ic, struct ieee80211_key *k)
{
    struct tkip_ctx *ctx;

    ctx = kmem_zalloc(sizeof (struct tkip_ctx), KM_SLEEP);
    if (ctx == NULL)
        return (NULL);

    ctx->tc_ic = ic;
    return (ctx);
}

static void
tkip_detach(struct ieee80211_key *k)
{
    struct tkip_ctx *ctx = k->wk_private;

    if (ctx != NULL)
        kmem_free(ctx, sizeof (struct tkip_ctx));
}

static int
tkip_setkey(struct ieee80211_key *k)
{
    if (k->wk_keylen != (128/NBBY))
        return (0);

    k->wk_keytsc = 1;       /* TSC starts at 1 */
    return (1);
}

/*
 * Add privacy headers appropriate for the specified key.
 */
static int
tkip_encap(struct ieee80211_key *k, mblk_t *mp, uint8_t keyid)
{
    struct tkip_ctx *ctx = k->wk_private;
    struct ieee80211com *ic = ctx->tc_ic;
    uint8_t *ivp;
    int hdrlen;

    /*
     * Handle TKIP counter measures requirement.
     */
    if (ic->ic_flags & IEEE80211_F_COUNTERM)
        return (0);

    hdrlen = ieee80211_hdrspace(mp->b_rptr);
    /*
     * Copy down 802.11 header and add the IV, KeyID, and ExtIV.
     */
    ivp = mp->b_rptr;
    ivp += hdrlen;

    ivp[0] = k->wk_keytsc >> 8;     /* TSC1 */
    ivp[1] = (ivp[0] | 0x20) & 0x7f;    /* WEP seed */
    ivp[2] = k->wk_keytsc >> 0;     /* TSC0 */
    ivp[3] = keyid | IEEE80211_WEP_EXTIV;   /* KeyID | ExtID */
    ivp[4] = k->wk_keytsc >> 16;        /* TSC2 */
    ivp[5] = k->wk_keytsc >> 24;        /* TSC3 */
    ivp[6] = k->wk_keytsc >> 32;        /* TSC4 */
    ivp[7] = k->wk_keytsc >> 40;        /* TSC5 */

    /*
     * NB: software TKIP is not supported.
     */
    if (k->wk_flags & IEEE80211_KEY_SWCRYPT)
        return (0);
    else
        k->wk_keytsc++;     /* wrap at 48 bits */

    return (1);
}

uint64_t
ieee80211_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.  If necessary, decrypt the frame using
 * the specified key.
 */
static int
tkip_decap(struct ieee80211_key *k, mblk_t *mp, int hdrlen)
{
    struct tkip_ctx *ctx = k->wk_private;
    struct ieee80211com *ic = ctx->tc_ic;
    struct ieee80211_frame tmp;
    uint8_t *ivp;
    uint64_t pn;

    /*
     * Header should have extended IV and sequence number;
     * verify the former and validate the latter.
     */
    ivp = mp->b_rptr + hdrlen;
    if ((ivp[IEEE80211_WEP_IVLEN] & IEEE80211_WEP_EXTIV) == 0) {
        /*
         * No extended IV; discard frame.
         */
        return (0);
    }
    /*
     * Handle TKIP counter measures requirement.
     */
    if (ic->ic_flags & IEEE80211_F_COUNTERM)
        return (0);

    /* NB: assume IEEEE80211_WEP_MINLEN covers the extended IV */
    pn = ieee80211_read_6(ivp[2], ivp[0], ivp[4], ivp[5], ivp[6], ivp[7]);
    ctx->rx_rsc = pn;
    if (ctx->rx_rsc <= k->wk_keyrsc)
        return (0);
    /*
     * NB: We can't update the rsc in the key until MIC is verified.
     *
     * We assume we are not preempted between doing the check above
     * and updating wk_keyrsc when stripping the MIC in tkip_demic.
     * Otherwise we might process another packet and discard it as
     * a replay.
     */

    /*
     * NB: software TKIP is not supported.
     */
    if (k->wk_flags & IEEE80211_KEY_SWCRYPT)
        return (0);

    /*
     * Copy up 802.11 header and strip crypto bits.
     */
    bcopy(mp->b_rptr, &tmp, hdrlen);
    bcopy(&tmp, mp->b_rptr + tkip.ic_header, hdrlen);
    mp->b_rptr += tkip.ic_header;
    mp->b_wptr -= tkip.ic_trailer;

    return (1);
}

/*
 * Add MIC to the frame as needed.
 */
/* ARGSUSED */
static int
tkip_enmic(struct ieee80211_key *k, mblk_t *mp, int force)
{
    return (1);
}

/*
 * Verify and strip MIC from the frame.
 */
/* ARGSUSED */
static int
tkip_demic(struct ieee80211_key *k, mblk_t *mp, int force)
{
    struct tkip_ctx *ctx = k->wk_private;

    /*
     * NB: software TKIP is not supported.
     */
    if (k->wk_flags & IEEE80211_KEY_SWMIC)
        return (0);
    /*
     * Strip MIC from the tail.
     */
    mp->b_wptr -= tkip.ic_miclen;
    /*
     * Ok to update rsc now that MIC has been verified.
     */
    k->wk_keyrsc = ctx->rx_rsc;

    return (1);
}