/*      $NetBSD: ieee80211_crypto_ccmp.c,v 1.20 2023/06/24 05:12:03 msaitoh Exp $       */

/*
 * 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.
 */

#include <sys/cdefs.h>
#ifdef __FreeBSD__
__FBSDID("$FreeBSD: src/sys/net80211/ieee80211_crypto_ccmp.c,v 1.7 2005/07/11 03:06:23 sam Exp $");
#endif
#ifdef __NetBSD__
__KERNEL_RCSID(0, "$NetBSD: ieee80211_crypto_ccmp.c,v 1.20 2023/06/24 05:12:03 msaitoh Exp $");
#endif

/*
 * 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.
 */
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/mbuf.h>
#include <sys/systm.h>

#include <sys/socket.h>

#include <net/if.h>
#include <net/if_ether.h>
#include <net/if_media.h>

#include <net80211/ieee80211_var.h>

#include <crypto/aes/aes.h>
#include <crypto/aes/aes_ccm.h>
#include <crypto/aes/aes_ccm_mbuf.h>

#define AES_BLOCK_LEN 16

struct ccmp_ctx {
        struct aesenc cc_aes;
        struct ieee80211com *cc_ic;     /* for diagnostics */
};

static  void *ccmp_attach(struct ieee80211com *, struct ieee80211_key *);
static  void ccmp_detach(struct ieee80211_key *);
static  int ccmp_setkey(struct ieee80211_key *);
static  int ccmp_encap(struct ieee80211_key *k, struct mbuf *, u_int8_t keyid);
static  int ccmp_decap(struct ieee80211_key *, struct mbuf *, int);
static  int ccmp_enmic(struct ieee80211_key *, struct mbuf *, int);
static  int ccmp_demic(struct ieee80211_key *, struct mbuf *, int);

const struct ieee80211_cipher 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,
};

#define ccmp    ieee80211_cipher_ccmp

static  int ccmp_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen);
static  int ccmp_decrypt(struct ieee80211_key *, u_int64_t pn,
                struct mbuf *, int hdrlen);

static void *
ccmp_attach(struct ieee80211com *ic, struct ieee80211_key *k)
{
        struct ccmp_ctx *ctx;

        ctx = kmem_intr_zalloc(sizeof(*ctx), KM_NOSLEEP);
        if (ctx == NULL) {
                ic->ic_stats.is_crypto_nomem++;
                return NULL;
        }
        ctx->cc_ic = ic;
        return ctx;
}

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

        kmem_intr_free(ctx, sizeof(*ctx));
}

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_ic, 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)
                aes_setenckey128(&ctx->cc_aes, k->wk_key);
        return 1;
}

/*
 * Add privacy headers appropriate for the specified key.
 */
static int
ccmp_encap(struct ieee80211_key *k, struct mbuf *m, 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, mtod(m, void *));
        ivp = mtod(m, u_int8_t *) + 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 need.
         */
        if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) &&
            !ccmp_encrypt(k, m, hdrlen))
                return 0;

        return 1;
}

/*
 * Add MIC to the frame as needed.
 */
static int
ccmp_enmic(struct ieee80211_key *k, struct mbuf *m,
    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 mbuf *m, int hdrlen)
{
        struct ccmp_ctx *ctx = k->wk_private;
        struct ieee80211_frame *wh;
        uint8_t *ivp;
        uint64_t pn;

        /*
         * Header should have extended IV and sequence number;
         * verify the former and validate the latter.
         */
        wh = mtod(m, struct ieee80211_frame *);
        ivp = mtod(m, uint8_t *) + hdrlen;
        if ((ivp[IEEE80211_WEP_IVLEN] & IEEE80211_WEP_EXTIV) == 0) {
                /*
                 * No extended IV; discard frame.
                 */
                IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
                        "[%s] Missing ExtIV for AES-CCM cipher\n",
                        ether_sprintf(wh->i_addr2));
                ctx->cc_ic->ic_stats.is_rx_ccmpformat++;
                return 0;
        }
        pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
        if (pn <= k->wk_keyrsc) {
                /*
                 * Replay violation.
                 */
                ieee80211_notify_replay_failure(ctx->cc_ic, wh, k, pn);
                ctx->cc_ic->ic_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, m, hdrlen))
                return 0;

        /*
         * Copy up 802.11 header and strip crypto bits.
         */
        memmove(mtod(m, u_int8_t *) + ccmp.ic_header, mtod(m, void *), hdrlen);
        m_adj(m, ccmp.ic_header);
        m_adj(m, -ccmp.ic_trailer);

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

        return 1;
}

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

/*
 * 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 aesenc *ctx, struct ieee80211_frame *wh,
    u_int64_t pn, size_t data_len, struct aes_ccm *aes_ccm)
{
        uint8_t nonce[13];
        uint8_t ad[32];
        uint8_t qos;
        size_t adlen;

#define IS_4ADDRESS(wh) \
        ((wh->i_fc[1] & IEEE80211_FC1_DIR_MASK) == IEEE80211_FC1_DIR_DSTODS)
#define IS_QOS_DATA(wh) ieee80211_has_qos(wh)

        /* nonce[0] is qos, determined later */
        IEEE80211_ADDR_COPY(nonce + 1, wh->i_addr2);
        nonce[7] = pn >> 40;
        nonce[8] = pn >> 32;
        nonce[9] = pn >> 24;
        nonce[10] = pn >> 16;
        nonce[11] = pn >> 8;
        nonce[12] = pn >> 0;

        ad[0] = wh->i_fc[0] & 0x8f;     /* XXX magic #s */
        ad[1] = wh->i_fc[1] & 0xc7;     /* XXX magic #s */
        /* NB: we know 3 addresses are contiguous */
        memcpy(ad + 2, wh->i_addr1, 3 * IEEE80211_ADDR_LEN);
        ad[20] = wh->i_seq[0] & IEEE80211_SEQ_FRAG_MASK;
        ad[21] = 0; /* all bits masked */

        /*
         * Construct variable-length portion of AAD based
         * on whether this is a 4-address frame/QOS frame.
         *
         * 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(ad + 22,
                    ((const struct ieee80211_frame_addr4 *)wh)->i_addr4);
                if (IS_QOS_DATA(wh)) {
                        const struct ieee80211_qosframe_addr4 *qwh4 =
                            (const struct ieee80211_qosframe_addr4 *)wh;
                        qos = qwh4->i_qos[0] & 0x0f; /* just priority bits */
                        ad[28] = qos;
                        ad[29] = 0;
                        adlen = 22 + IEEE80211_ADDR_LEN + 2;
                } else {
                        qos = 0;
                        adlen = 22 + IEEE80211_ADDR_LEN;
                }
        } else {
                if (IS_QOS_DATA(wh)) {
                        const struct ieee80211_qosframe *qwh =
                            (const struct ieee80211_qosframe *)wh;
                        qos = qwh->i_qos[0] & 0x0f; /* just priority bits */
                        ad[22] = qos;
                        ad[23] = 0;
                        adlen = 22 + 2;
                } else {
                        qos = 0;
                        adlen = 22;
                }
        }
        nonce[0] = qos;

        aes_ccm_init(aes_ccm, AES_128_NROUNDS, ctx, 2 /* L, counter octets */,
            IEEE80211_WEP_MICLEN, nonce, sizeof nonce, ad, adlen, data_len);

#undef  IS_QOS_DATA
#undef  IS_4ADDRESS
}

static int
ccmp_encrypt(struct ieee80211_key *key, struct mbuf *m, int hdrlen)
{
        struct ccmp_ctx *ctx = key->wk_private;
        struct ieee80211_frame *wh;
        struct aes_ccm aes_ccm;
        size_t data_len;
        uint8_t mic[IEEE80211_WEP_MICLEN];

        KASSERT(hdrlen >= 0);
        KASSERT(hdrlen < m->m_pkthdr.len);
        KASSERT(ccmp.ic_header <= m->m_pkthdr.len - hdrlen);

        ctx->cc_ic->ic_stats.is_crypto_ccmp++;

        wh = mtod(m, struct ieee80211_frame *);
        data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header);
        ccmp_init_blocks(&ctx->cc_aes, wh, key->wk_keytsc, data_len, &aes_ccm);
        aes_ccm_enc_mbuf(&aes_ccm, m, hdrlen + ccmp.ic_header, data_len, mic);

        return m_append(m, ccmp.ic_trailer, mic);
}

static int
ccmp_decrypt(struct ieee80211_key *key, u_int64_t pn, struct mbuf *m,
    int hdrlen)
{
        struct ccmp_ctx *ctx = key->wk_private;
        struct ieee80211_frame *wh;
        struct aes_ccm aes_ccm;
        size_t data_len;
        uint8_t mic[IEEE80211_WEP_MICLEN];

        KASSERT(hdrlen >= 0);
        KASSERT(hdrlen < m->m_pkthdr.len);
        KASSERT(ccmp.ic_header < m->m_pkthdr.len - hdrlen);
        KASSERT(ccmp.ic_trailer < m->m_pkthdr.len - (hdrlen + ccmp.ic_header));

        ctx->cc_ic->ic_stats.is_crypto_ccmp++;

        wh = mtod(m, struct ieee80211_frame *);
        data_len = m->m_pkthdr.len - (hdrlen + ccmp.ic_header + ccmp.ic_trailer);
        ccmp_init_blocks(&ctx->cc_aes, wh, pn, data_len, &aes_ccm);
        m_copydata(m, m->m_pkthdr.len - ccmp.ic_trailer, ccmp.ic_trailer, mic);

        if (!aes_ccm_dec_mbuf(&aes_ccm, m, hdrlen + ccmp.ic_header, data_len,
                mic)) {
                IEEE80211_DPRINTF(ctx->cc_ic, IEEE80211_MSG_CRYPTO,
                    "[%s] AES-CCM decrypt failed; MIC mismatch\n",
                    ether_sprintf(wh->i_addr2));
                ctx->cc_ic->ic_stats.is_rx_ccmpmic++;
                return 0;
        }

        return 1;
}

IEEE80211_CRYPTO_SETUP(ccmp_register)
{
        ieee80211_crypto_register(&ccmp);
}