ieee80211_crypto_ccmp.c.svn-base

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/*-
 * 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.
 *
 * $Id$
 */

/*
 * 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 <[e-mail]>
 *