FreeBSD-5.3/sys/net80211/ieee80211_crypto.c
/*-
* Copyright (c) 2001 Atsushi Onoe
* Copyright (c) 2002, 2003 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>
__FBSDID("$FreeBSD: src/sys/net80211/ieee80211_crypto.c,v 1.3 2003/10/17 23:15:30 sam Exp $");
#include "opt_inet.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/endian.h>
#include <sys/errno.h>
#include <sys/bus.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <machine/atomic.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_media.h>
#include <net/if_arp.h>
#include <net/ethernet.h>
#include <net/if_llc.h>
#include <net80211/ieee80211_var.h>
#include <net/bpf.h>
#ifdef INET
#include <netinet/in.h>
#include <netinet/if_ether.h>
#endif
#include <crypto/rc4/rc4.h>
#define arc4_ctxlen() sizeof (struct rc4_state)
#define arc4_setkey(_c,_k,_l) rc4_init(_c,_k,_l)
#define arc4_encrypt(_c,_d,_s,_l) rc4_crypt(_c,_s,_d,_l)
static void ieee80211_crc_init(void);
static u_int32_t ieee80211_crc_update(u_int32_t crc, u_int8_t *buf, int len);
void
ieee80211_crypto_attach(struct ifnet *ifp)
{
struct ieee80211com *ic = (void *)ifp;
/*
* Setup crypto support.
*/
ieee80211_crc_init();
ic->ic_iv = arc4random();
}
void
ieee80211_crypto_detach(struct ifnet *ifp)
{
struct ieee80211com *ic = (void *)ifp;
if (ic->ic_wep_ctx != NULL) {
free(ic->ic_wep_ctx, M_DEVBUF);
ic->ic_wep_ctx = NULL;
}
}
struct mbuf *
ieee80211_wep_crypt(struct ifnet *ifp, struct mbuf *m0, int txflag)
{
struct ieee80211com *ic = (void *)ifp;
struct mbuf *m, *n, *n0;
struct ieee80211_frame *wh;
int i, left, len, moff, noff, kid;
u_int32_t iv, crc;
u_int8_t *ivp;
void *ctx;
u_int8_t keybuf[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE];
u_int8_t crcbuf[IEEE80211_WEP_CRCLEN];
n0 = NULL;
if ((ctx = ic->ic_wep_ctx) == NULL) {
ctx = malloc(arc4_ctxlen(), M_DEVBUF, M_NOWAIT);
if (ctx == NULL) {
ic->ic_stats.is_crypto_nomem++;
goto fail;
}
ic->ic_wep_ctx = ctx;
}
m = m0;
left = m->m_pkthdr.len;
MGET(n, M_DONTWAIT, m->m_type);
n0 = n;
if (n == NULL) {
if (txflag)
ic->ic_stats.is_tx_nombuf++;
else
ic->ic_stats.is_rx_nombuf++;
goto fail;
}
M_MOVE_PKTHDR(n, m);
len = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN + IEEE80211_WEP_CRCLEN;
if (txflag) {
n->m_pkthdr.len += len;
} else {
n->m_pkthdr.len -= len;
left -= len;
}
n->m_len = MHLEN;
if (n->m_pkthdr.len >= MINCLSIZE) {
MCLGET(n, M_DONTWAIT);
if (n->m_flags & M_EXT)
n->m_len = n->m_ext.ext_size;
}
len = sizeof(struct ieee80211_frame);
memcpy(mtod(n, caddr_t), mtod(m, caddr_t), len);
wh = mtod(n, struct ieee80211_frame *);
left -= len;
moff = len;
noff = len;
if (txflag) {
kid = ic->ic_wep_txkey;
wh->i_fc[1] |= IEEE80211_FC1_WEP;
iv = ic->ic_iv;
/*
* Skip 'bad' IVs from Fluhrer/Mantin/Shamir:
* (B, 255, N) with 3 <= B < 8
*/
if (iv >= 0x03ff00 &&
(iv & 0xf8ff00) == 0x00ff00)
iv += 0x000100;
ic->ic_iv = iv + 1;
/* put iv in little endian to prepare 802.11i */
ivp = mtod(n, u_int8_t *) + noff;
for (i = 0; i < IEEE80211_WEP_IVLEN; i++) {
ivp[i] = iv & 0xff;
iv >>= 8;
}
ivp[IEEE80211_WEP_IVLEN] = kid << 6; /* pad and keyid */
noff += IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN;
} else {
wh->i_fc[1] &= ~IEEE80211_FC1_WEP;
ivp = mtod(m, u_int8_t *) + moff;
kid = ivp[IEEE80211_WEP_IVLEN] >> 6;
moff += IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN;
}
memcpy(keybuf, ivp, IEEE80211_WEP_IVLEN);
memcpy(keybuf + IEEE80211_WEP_IVLEN, ic->ic_nw_keys[kid].wk_key,
ic->ic_nw_keys[kid].wk_len);
arc4_setkey(ctx, keybuf,
IEEE80211_WEP_IVLEN + ic->ic_nw_keys[kid].wk_len);
/* encrypt with calculating CRC */
crc = ~0;
while (left > 0) {
len = m->m_len - moff;
if (len == 0) {
m = m->m_next;
moff = 0;
continue;
}
if (len > n->m_len - noff) {
len = n->m_len - noff;
if (len == 0) {
MGET(n->m_next, M_DONTWAIT, n->m_type);
if (n->m_next == NULL) {
if (txflag)
ic->ic_stats.is_tx_nombuf++;
else
ic->ic_stats.is_rx_nombuf++;
goto fail;
}
n = n->m_next;
n->m_len = MLEN;
if (left >= MINCLSIZE) {
MCLGET(n, M_DONTWAIT);
if (n->m_flags & M_EXT)
n->m_len = n->m_ext.ext_size;
}
noff = 0;
continue;
}
}
if (len > left)
len = left;
arc4_encrypt(ctx, mtod(n, caddr_t) + noff,
mtod(m, caddr_t) + moff, len);
if (txflag)
crc = ieee80211_crc_update(crc,
mtod(m, u_int8_t *) + moff, len);
else
crc = ieee80211_crc_update(crc,
mtod(n, u_int8_t *) + noff, len);
left -= len;
moff += len;
noff += len;
}
crc = ~crc;
if (txflag) {
*(u_int32_t *)crcbuf = htole32(crc);
if (n->m_len >= noff + sizeof(crcbuf))
n->m_len = noff + sizeof(crcbuf);
else {
n->m_len = noff;
MGET(n->m_next, M_DONTWAIT, n->m_type);
if (n->m_next == NULL) {
ic->ic_stats.is_tx_nombuf++;
goto fail;
}
n = n->m_next;
n->m_len = sizeof(crcbuf);
noff = 0;
}
arc4_encrypt(ctx, mtod(n, caddr_t) + noff, crcbuf,
sizeof(crcbuf));
} else {
n->m_len = noff;
for (noff = 0; noff < sizeof(crcbuf); noff += len) {
len = sizeof(crcbuf) - noff;
if (len > m->m_len - moff)
len = m->m_len - moff;
if (len > 0)
arc4_encrypt(ctx, crcbuf + noff,
mtod(m, caddr_t) + moff, len);
m = m->m_next;
moff = 0;
}
if (crc != le32toh(*(u_int32_t *)crcbuf)) {
#ifdef IEEE80211_DEBUG
if (ieee80211_debug) {
if_printf(ifp, "decrypt CRC error\n");
if (ieee80211_debug > 1)
ieee80211_dump_pkt(n0->m_data,
n0->m_len, -1, -1);
}
#endif
ic->ic_stats.is_rx_decryptcrc++;
goto fail;
}
}
m_freem(m0);
return n0;
fail:
m_freem(m0);
m_freem(n0);
return NULL;
}
/*
* CRC 32 -- routine from RFC 2083
*/
/* Table of CRCs of all 8-bit messages */
static u_int32_t ieee80211_crc_table[256];
/* Make the table for a fast CRC. */
static void
ieee80211_crc_init(void)
{
u_int32_t c;
int n, k;
for (n = 0; n < 256; n++) {
c = (u_int32_t)n;
for (k = 0; k < 8; k++) {
if (c & 1)
c = 0xedb88320UL ^ (c >> 1);
else
c = c >> 1;
}
ieee80211_crc_table[n] = c;
}
}
/*
* Update a running CRC with the bytes buf[0..len-1]--the CRC
* should be initialized to all 1's, and the transmitted value
* is the 1's complement of the final running CRC
*/
static u_int32_t
ieee80211_crc_update(u_int32_t crc, u_int8_t *buf, int len)
{
u_int8_t *endbuf;
for (endbuf = buf + len; buf < endbuf; buf++)
crc = ieee80211_crc_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);
return crc;
}