ieee80211_crypto.c revision 1.3
1 /* $NetBSD: ieee80211_crypto.c,v 1.3 2003/09/14 01:14:54 dyoung Exp $ */ 2 /*- 3 * Copyright (c) 2001 Atsushi Onoe 4 * Copyright (c) 2002, 2003 Sam Leffler, Errno Consulting 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 18 * Alternatively, this software may be distributed under the terms of the 19 * GNU General Public License ("GPL") version 2 as published by the Free 20 * Software Foundation. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 #ifdef __FreeBSD__ 36 __FBSDID("$FreeBSD: src/sys/net80211/ieee80211_crypto.c,v 1.2 2003/06/27 05:13:52 sam Exp $"); 37 #else 38 __KERNEL_RCSID(0, "$NetBSD: ieee80211_crypto.c,v 1.3 2003/09/14 01:14:54 dyoung Exp $"); 39 #endif 40 41 #include "opt_inet.h" 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/mbuf.h> 46 #include <sys/malloc.h> 47 #include <sys/kernel.h> 48 #include <sys/socket.h> 49 #include <sys/sockio.h> 50 #include <sys/endian.h> 51 #include <sys/errno.h> 52 #include <sys/bus.h> 53 #include <sys/proc.h> 54 #include <sys/sysctl.h> 55 56 #ifdef __FreeBSD__ 57 #include <machine/atomic.h> 58 #endif 59 60 #include <net/if.h> 61 #include <net/if_dl.h> 62 #include <net/if_media.h> 63 #include <net/if_arp.h> 64 #ifdef __FreeBSD__ 65 #include <net/ethernet.h> 66 #endif 67 #include <net/if_llc.h> 68 69 #include <net80211/ieee80211_var.h> 70 71 #include <net/bpf.h> 72 73 #ifdef INET 74 #include <netinet/in.h> 75 #include <netinet/if_ether.h> 76 #endif 77 78 #ifdef __FreeBSD__ 79 #include <crypto/rc4/rc4.h> 80 #define arc4_ctxlen() sizeof (struct rc4_state) 81 #define arc4_setkey(_c,_k,_l) rc4_init(_c,_k,_l) 82 #define arc4_encrypt(_c,_d,_s,_l) rc4_crypt(_c,_s,_d,_l) 83 #else 84 #include <crypto/arc4/arc4.h> 85 #endif 86 87 static void ieee80211_crc_init(void); 88 static u_int32_t ieee80211_crc_update(u_int32_t crc, u_int8_t *buf, int len); 89 90 void 91 ieee80211_crypto_attach(struct ifnet *ifp) 92 { 93 struct ieee80211com *ic = (void *)ifp; 94 95 /* 96 * Setup crypto support. 97 */ 98 ieee80211_crc_init(); 99 ic->ic_iv = arc4random(); 100 } 101 102 void 103 ieee80211_crypto_detach(struct ifnet *ifp) 104 { 105 struct ieee80211com *ic = (void *)ifp; 106 107 if (ic->ic_wep_ctx != NULL) { 108 free(ic->ic_wep_ctx, M_DEVBUF); 109 ic->ic_wep_ctx = NULL; 110 } 111 } 112 113 struct mbuf * 114 ieee80211_wep_crypt(struct ifnet *ifp, struct mbuf *m0, int txflag) 115 { 116 struct ieee80211com *ic = (void *)ifp; 117 struct mbuf *m, *n, *n0; 118 struct ieee80211_frame *wh; 119 int i, left, len, moff, noff, kid; 120 u_int32_t iv, crc; 121 u_int8_t *ivp; 122 void *ctx; 123 u_int8_t keybuf[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE]; 124 u_int8_t crcbuf[IEEE80211_WEP_CRCLEN]; 125 126 n0 = NULL; 127 if ((ctx = ic->ic_wep_ctx) == NULL) { 128 ctx = malloc(arc4_ctxlen(), M_DEVBUF, M_NOWAIT); 129 if (ctx == NULL) 130 goto fail; 131 ic->ic_wep_ctx = ctx; 132 } 133 m = m0; 134 left = m->m_pkthdr.len; 135 MGET(n, M_DONTWAIT, m->m_type); 136 n0 = n; 137 if (n == NULL) 138 goto fail; 139 M_MOVE_PKTHDR(n, m); 140 len = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN + IEEE80211_WEP_CRCLEN; 141 if (txflag) { 142 n->m_pkthdr.len += len; 143 } else { 144 n->m_pkthdr.len -= len; 145 left -= len; 146 } 147 n->m_len = MHLEN; 148 if (n->m_pkthdr.len >= MINCLSIZE) { 149 MCLGET(n, M_DONTWAIT); 150 if (n->m_flags & M_EXT) 151 n->m_len = n->m_ext.ext_size; 152 } 153 len = sizeof(struct ieee80211_frame); 154 memcpy(mtod(n, caddr_t), mtod(m, caddr_t), len); 155 wh = mtod(n, struct ieee80211_frame *); 156 left -= len; 157 moff = len; 158 noff = len; 159 if (txflag) { 160 kid = ic->ic_wep_txkey; 161 wh->i_fc[1] |= IEEE80211_FC1_WEP; 162 iv = ic->ic_iv; 163 /* 164 * Skip 'bad' IVs from Fluhrer/Mantin/Shamir: 165 * (B, 255, N) with 3 <= B < 8 166 */ 167 if (iv >= 0x03ff00 && 168 (iv & 0xf8ff00) == 0x00ff00) 169 iv += 0x000100; 170 ic->ic_iv = iv + 1; 171 /* put iv in little endian to prepare 802.11i */ 172 ivp = mtod(n, u_int8_t *) + noff; 173 for (i = 0; i < IEEE80211_WEP_IVLEN; i++) { 174 ivp[i] = iv & 0xff; 175 iv >>= 8; 176 } 177 ivp[IEEE80211_WEP_IVLEN] = kid << 6; /* pad and keyid */ 178 noff += IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN; 179 } else { 180 wh->i_fc[1] &= ~IEEE80211_FC1_WEP; 181 ivp = mtod(m, u_int8_t *) + moff; 182 kid = ivp[IEEE80211_WEP_IVLEN] >> 6; 183 moff += IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN; 184 } 185 memcpy(keybuf, ivp, IEEE80211_WEP_IVLEN); 186 memcpy(keybuf + IEEE80211_WEP_IVLEN, ic->ic_nw_keys[kid].wk_key, 187 ic->ic_nw_keys[kid].wk_len); 188 arc4_setkey(ctx, keybuf, 189 IEEE80211_WEP_IVLEN + ic->ic_nw_keys[kid].wk_len); 190 191 /* encrypt with calculating CRC */ 192 crc = ~0; 193 while (left > 0) { 194 len = m->m_len - moff; 195 if (len == 0) { 196 m = m->m_next; 197 moff = 0; 198 continue; 199 } 200 if (len > n->m_len - noff) { 201 len = n->m_len - noff; 202 if (len == 0) { 203 MGET(n->m_next, M_DONTWAIT, n->m_type); 204 if (n->m_next == NULL) 205 goto fail; 206 n = n->m_next; 207 n->m_len = MLEN; 208 if (left >= MINCLSIZE) { 209 MCLGET(n, M_DONTWAIT); 210 if (n->m_flags & M_EXT) 211 n->m_len = n->m_ext.ext_size; 212 } 213 noff = 0; 214 continue; 215 } 216 } 217 if (len > left) 218 len = left; 219 arc4_encrypt(ctx, mtod(n, caddr_t) + noff, 220 mtod(m, caddr_t) + moff, len); 221 if (txflag) 222 crc = ieee80211_crc_update(crc, 223 mtod(m, u_int8_t *) + moff, len); 224 else 225 crc = ieee80211_crc_update(crc, 226 mtod(n, u_int8_t *) + noff, len); 227 left -= len; 228 moff += len; 229 noff += len; 230 } 231 crc = ~crc; 232 if (txflag) { 233 *(u_int32_t *)crcbuf = htole32(crc); 234 if (n->m_len >= noff + sizeof(crcbuf)) 235 n->m_len = noff + sizeof(crcbuf); 236 else { 237 n->m_len = noff; 238 MGET(n->m_next, M_DONTWAIT, n->m_type); 239 if (n->m_next == NULL) 240 goto fail; 241 n = n->m_next; 242 n->m_len = sizeof(crcbuf); 243 noff = 0; 244 } 245 arc4_encrypt(ctx, mtod(n, caddr_t) + noff, crcbuf, 246 sizeof(crcbuf)); 247 } else { 248 n->m_len = noff; 249 for (noff = 0; noff < sizeof(crcbuf); noff += len) { 250 len = sizeof(crcbuf) - noff; 251 if (len > m->m_len - moff) 252 len = m->m_len - moff; 253 if (len > 0) 254 arc4_encrypt(ctx, crcbuf + noff, 255 mtod(m, caddr_t) + moff, len); 256 m = m->m_next; 257 moff = 0; 258 } 259 if (crc != le32toh(*(u_int32_t *)crcbuf)) { 260 #ifdef IEEE80211_DEBUG 261 if (ieee80211_debug) { 262 if_printf(ifp, "decrypt CRC error\n"); 263 if (ieee80211_debug > 1) 264 ieee80211_dump_pkt(n0->m_data, 265 n0->m_len, -1, -1); 266 } 267 #endif 268 goto fail; 269 } 270 } 271 m_freem(m0); 272 return n0; 273 274 fail: 275 m_freem(m0); 276 m_freem(n0); 277 return NULL; 278 } 279 280 /* 281 * CRC 32 -- routine from RFC 2083 282 */ 283 284 /* Table of CRCs of all 8-bit messages */ 285 static u_int32_t ieee80211_crc_table[256]; 286 287 /* Make the table for a fast CRC. */ 288 static void 289 ieee80211_crc_init(void) 290 { 291 u_int32_t c; 292 int n, k; 293 294 for (n = 0; n < 256; n++) { 295 c = (u_int32_t)n; 296 for (k = 0; k < 8; k++) { 297 if (c & 1) 298 c = 0xedb88320UL ^ (c >> 1); 299 else 300 c = c >> 1; 301 } 302 ieee80211_crc_table[n] = c; 303 } 304 } 305 306 /* 307 * Update a running CRC with the bytes buf[0..len-1]--the CRC 308 * should be initialized to all 1's, and the transmitted value 309 * is the 1's complement of the final running CRC 310 */ 311 312 static u_int32_t 313 ieee80211_crc_update(u_int32_t crc, u_int8_t *buf, int len) 314 { 315 u_int8_t *endbuf; 316 317 for (endbuf = buf + len; buf < endbuf; buf++) 318 crc = ieee80211_crc_table[(crc ^ *buf) & 0xff] ^ (crc >> 8); 319 return crc; 320 } 321
Indexes created Tue Sep 23 22:09:46 GMT 2025