| 1 | /*- |
| 2 | * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions |
| 7 | * are met: |
| 8 | * 1. Redistributions of source code must retain the above copyright |
| 9 | * notice, this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer in the |
| 12 | * documentation and/or other materials provided with the distribution. |
| 13 | * 3. The name of the author may not be used to endorse or promote products |
| 14 | * derived from this software without specific prior written permission. |
| 15 | * |
| 16 | * Alternatively, this software may be distributed under the terms of the |
| 17 | * GNU General Public License ("GPL") version 2 as published by the Free |
| 18 | * Software Foundation. |
| 19 | * |
| 20 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 21 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 22 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 23 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 24 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 25 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 26 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 27 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 28 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 29 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 30 | */ |
| 31 | |
| 32 | #include <sys/cdefs.h> |
| 33 | #ifdef __FreeBSD__ |
| 34 | __FBSDID("$FreeBSD: src/sys/net80211/ieee80211_crypto_wep.c,v 1.7 2005/06/10 16:11:24 sam Exp $" ); |
| 35 | #endif |
| 36 | #ifdef __NetBSD__ |
| 37 | __KERNEL_RCSID(0, "$NetBSD: ieee80211_crypto_wep.c,v 1.9 2016/10/09 14:50:20 christos Exp $" ); |
| 38 | #endif |
| 39 | |
| 40 | /* |
| 41 | * IEEE 802.11 WEP crypto support. |
| 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/endian.h> |
| 49 | |
| 50 | #include <sys/socket.h> |
| 51 | |
| 52 | #include <net/if.h> |
| 53 | #include <net/if_ether.h> |
| 54 | #include <net/if_media.h> |
| 55 | |
| 56 | #include <net80211/ieee80211_var.h> |
| 57 | |
| 58 | static void *wep_attach(struct ieee80211com *, struct ieee80211_key *); |
| 59 | static void wep_detach(struct ieee80211_key *); |
| 60 | static int wep_setkey(struct ieee80211_key *); |
| 61 | static int wep_encap(struct ieee80211_key *, struct mbuf *, u_int8_t keyid); |
| 62 | static int wep_decap(struct ieee80211_key *, struct mbuf *, int hdrlen); |
| 63 | static int wep_enmic(struct ieee80211_key *, struct mbuf *, int); |
| 64 | static int wep_demic(struct ieee80211_key *, struct mbuf *, int); |
| 65 | |
| 66 | const struct ieee80211_cipher ieee80211_cipher_wep = { |
| 67 | .ic_name = "WEP" , |
| 68 | .ic_cipher = IEEE80211_CIPHER_WEP, |
| 69 | .ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN, |
| 70 | .ic_trailer = IEEE80211_WEP_CRCLEN, |
| 71 | .ic_miclen = 0, |
| 72 | .ic_attach = wep_attach, |
| 73 | .ic_detach = wep_detach, |
| 74 | .ic_setkey = wep_setkey, |
| 75 | .ic_encap = wep_encap, |
| 76 | .ic_decap = wep_decap, |
| 77 | .ic_enmic = wep_enmic, |
| 78 | .ic_demic = wep_demic, |
| 79 | }; |
| 80 | |
| 81 | #define wep ieee80211_cipher_wep |
| 82 | |
| 83 | static int wep_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen); |
| 84 | static int wep_decrypt(struct ieee80211_key *, struct mbuf *, int hdrlen); |
| 85 | |
| 86 | struct wep_ctx { |
| 87 | struct ieee80211com *wc_ic; /* for diagnostics */ |
| 88 | u_int32_t wc_iv; /* initial vector for crypto */ |
| 89 | }; |
| 90 | |
| 91 | static void * |
| 92 | wep_attach(struct ieee80211com *ic, struct ieee80211_key *k) |
| 93 | { |
| 94 | struct wep_ctx *ctx; |
| 95 | |
| 96 | ctx = malloc(sizeof(struct wep_ctx), |
| 97 | M_DEVBUF, M_NOWAIT | M_ZERO); |
| 98 | if (ctx == NULL) { |
| 99 | ic->ic_stats.is_crypto_nomem++; |
| 100 | return NULL; |
| 101 | } |
| 102 | |
| 103 | ctx->wc_ic = ic; |
| 104 | get_random_bytes(&ctx->wc_iv, sizeof(ctx->wc_iv)); |
| 105 | return ctx; |
| 106 | } |
| 107 | |
| 108 | static void |
| 109 | wep_detach(struct ieee80211_key *k) |
| 110 | { |
| 111 | struct wep_ctx *ctx = k->wk_private; |
| 112 | |
| 113 | free(ctx, M_DEVBUF); |
| 114 | } |
| 115 | |
| 116 | static int |
| 117 | wep_setkey(struct ieee80211_key *k) |
| 118 | { |
| 119 | return k->wk_keylen >= 40/NBBY; |
| 120 | } |
| 121 | |
| 122 | /* |
| 123 | * Add privacy headers appropriate for the specified key. |
| 124 | */ |
| 125 | static int |
| 126 | wep_encap(struct ieee80211_key *k, struct mbuf *m, u_int8_t keyid) |
| 127 | { |
| 128 | struct wep_ctx *ctx = k->wk_private; |
| 129 | struct ieee80211com *ic = ctx->wc_ic; |
| 130 | u_int32_t iv; |
| 131 | u_int8_t *ivp; |
| 132 | int hdrlen; |
| 133 | |
| 134 | hdrlen = ieee80211_hdrspace(ic, mtod(m, void *)); |
| 135 | |
| 136 | /* |
| 137 | * Copy down 802.11 header and add the IV + KeyID. |
| 138 | */ |
| 139 | M_PREPEND(m, wep.ic_header, M_NOWAIT); |
| 140 | if (m == NULL) |
| 141 | return 0; |
| 142 | ivp = mtod(m, u_int8_t *); |
| 143 | ovbcopy(ivp + wep.ic_header, ivp, hdrlen); |
| 144 | ivp += hdrlen; |
| 145 | |
| 146 | /* |
| 147 | * XXX |
| 148 | * IV must not duplicate during the lifetime of the key. |
| 149 | * But no mechanism to renew keys is defined in IEEE 802.11 |
| 150 | * for WEP. And the IV may be duplicated at other stations |
| 151 | * because the session key itself is shared. So we use a |
| 152 | * pseudo random IV for now, though it is not the right way. |
| 153 | * |
| 154 | * NB: Rather than use a strictly random IV we select a |
| 155 | * random one to start and then increment the value for |
| 156 | * each frame. This is an explicit tradeoff between |
| 157 | * overhead and security. Given the basic insecurity of |
| 158 | * WEP this seems worthwhile. |
| 159 | */ |
| 160 | |
| 161 | /* |
| 162 | * Skip 'bad' IVs from Fluhrer/Mantin/Shamir: |
| 163 | * (B, 255, N) with 3 <= B < 16 and 0 <= N <= 255 |
| 164 | */ |
| 165 | iv = ctx->wc_iv; |
| 166 | if ((iv & 0xff00) == 0xff00) { |
| 167 | int B = (iv & 0xff0000) >> 16; |
| 168 | if (3 <= B && B < 16) |
| 169 | iv += 0x0100; |
| 170 | } |
| 171 | ctx->wc_iv = iv + 1; |
| 172 | |
| 173 | /* |
| 174 | * NB: Preserve byte order of IV for packet |
| 175 | * sniffers; it doesn't matter otherwise. |
| 176 | */ |
| 177 | #if _BYTE_ORDER == _BIG_ENDIAN |
| 178 | ivp[0] = iv >> 0; |
| 179 | ivp[1] = iv >> 8; |
| 180 | ivp[2] = iv >> 16; |
| 181 | #else |
| 182 | ivp[2] = iv >> 0; |
| 183 | ivp[1] = iv >> 8; |
| 184 | ivp[0] = iv >> 16; |
| 185 | #endif |
| 186 | ivp[3] = keyid; |
| 187 | |
| 188 | /* |
| 189 | * Finally, do software encrypt if neeed. |
| 190 | */ |
| 191 | if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) && |
| 192 | !wep_encrypt(k, m, hdrlen)) |
| 193 | return 0; |
| 194 | |
| 195 | return 1; |
| 196 | } |
| 197 | |
| 198 | /* |
| 199 | * Add MIC to the frame as needed. |
| 200 | */ |
| 201 | static int |
| 202 | wep_enmic(struct ieee80211_key *k, struct mbuf *m, |
| 203 | int force) |
| 204 | { |
| 205 | |
| 206 | return 1; |
| 207 | } |
| 208 | |
| 209 | /* |
| 210 | * Validate and strip privacy headers (and trailer) for a |
| 211 | * received frame. If necessary, decrypt the frame using |
| 212 | * the specified key. |
| 213 | */ |
| 214 | static int |
| 215 | wep_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen) |
| 216 | { |
| 217 | struct wep_ctx *ctx = k->wk_private; |
| 218 | struct ieee80211_frame *wh; |
| 219 | |
| 220 | wh = mtod(m, struct ieee80211_frame *); |
| 221 | |
| 222 | /* |
| 223 | * Check if the device handled the decrypt in hardware. |
| 224 | * If so we just strip the header; otherwise we need to |
| 225 | * handle the decrypt in software. |
| 226 | */ |
| 227 | if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) && |
| 228 | !wep_decrypt(k, m, hdrlen)) { |
| 229 | IEEE80211_DPRINTF(ctx->wc_ic, IEEE80211_MSG_CRYPTO, |
| 230 | "[%s] WEP ICV mismatch on decrypt\n" , |
| 231 | ether_sprintf(wh->i_addr2)); |
| 232 | ctx->wc_ic->ic_stats.is_rx_wepfail++; |
| 233 | return 0; |
| 234 | } |
| 235 | |
| 236 | /* |
| 237 | * Copy up 802.11 header and strip crypto bits. |
| 238 | */ |
| 239 | ovbcopy(mtod(m, void *), mtod(m, u_int8_t *) + wep.ic_header, hdrlen); |
| 240 | m_adj(m, wep.ic_header); |
| 241 | m_adj(m, -wep.ic_trailer); |
| 242 | |
| 243 | return 1; |
| 244 | } |
| 245 | |
| 246 | /* |
| 247 | * Verify and strip MIC from the frame. |
| 248 | */ |
| 249 | static int |
| 250 | wep_demic(struct ieee80211_key *k, struct mbuf *skb, |
| 251 | int force) |
| 252 | { |
| 253 | return 1; |
| 254 | } |
| 255 | |
| 256 | static const uint32_t crc32_table[256] = { |
| 257 | 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L, |
| 258 | 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L, |
| 259 | 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L, |
| 260 | 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL, |
| 261 | 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L, |
| 262 | 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L, |
| 263 | 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L, |
| 264 | 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL, |
| 265 | 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L, |
| 266 | 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL, |
| 267 | 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, |
| 268 | 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L, |
| 269 | 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L, |
| 270 | 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL, |
| 271 | 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL, |
| 272 | 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L, |
| 273 | 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL, |
| 274 | 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L, |
| 275 | 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L, |
| 276 | 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L, |
| 277 | 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL, |
| 278 | 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L, |
| 279 | 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L, |
| 280 | 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL, |
| 281 | 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L, |
| 282 | 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L, |
| 283 | 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L, |
| 284 | 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L, |
| 285 | 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L, |
| 286 | 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL, |
| 287 | 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL, |
| 288 | 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L, |
| 289 | 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L, |
| 290 | 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL, |
| 291 | 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL, |
| 292 | 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L, |
| 293 | 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL, |
| 294 | 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L, |
| 295 | 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL, |
| 296 | 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L, |
| 297 | 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL, |
| 298 | 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L, |
| 299 | 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L, |
| 300 | 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL, |
| 301 | 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L, |
| 302 | 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L, |
| 303 | 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, |
| 304 | 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L, |
| 305 | 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L, |
| 306 | 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L, |
| 307 | 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL, |
| 308 | 0x2d02ef8dL |
| 309 | }; |
| 310 | |
| 311 | static int |
| 312 | wep_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen) |
| 313 | { |
| 314 | #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0) |
| 315 | struct wep_ctx *ctx = key->wk_private; |
| 316 | struct mbuf *m = m0; |
| 317 | u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE]; |
| 318 | uint8_t icv[IEEE80211_WEP_CRCLEN]; |
| 319 | uint32_t i, j, k, crc; |
| 320 | size_t buflen, data_len; |
| 321 | uint8_t S[256]; |
| 322 | uint8_t *pos; |
| 323 | u_int off, keylen; |
| 324 | |
| 325 | ctx->wc_ic->ic_stats.is_crypto_wep++; |
| 326 | |
| 327 | /* NB: this assumes the header was pulled up */ |
| 328 | memcpy(rc4key, mtod(m, u_int8_t *) + hdrlen, IEEE80211_WEP_IVLEN); |
| 329 | memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen); |
| 330 | |
| 331 | /* Setup RC4 state */ |
| 332 | for (i = 0; i < 256; i++) |
| 333 | S[i] = i; |
| 334 | j = 0; |
| 335 | keylen = key->wk_keylen + IEEE80211_WEP_IVLEN; |
| 336 | for (i = 0; i < 256; i++) { |
| 337 | j = (j + S[i] + rc4key[i % keylen]) & 0xff; |
| 338 | S_SWAP(i, j); |
| 339 | } |
| 340 | |
| 341 | off = hdrlen + wep.ic_header; |
| 342 | data_len = m->m_pkthdr.len - off; |
| 343 | |
| 344 | /* Compute CRC32 over unencrypted data and apply RC4 to data */ |
| 345 | crc = ~0; |
| 346 | i = j = 0; |
| 347 | pos = mtod(m, uint8_t *) + off; |
| 348 | buflen = m->m_len - off; |
| 349 | for (;;) { |
| 350 | if (buflen > data_len) |
| 351 | buflen = data_len; |
| 352 | data_len -= buflen; |
| 353 | for (k = 0; k < buflen; k++) { |
| 354 | crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8); |
| 355 | i = (i + 1) & 0xff; |
| 356 | j = (j + S[i]) & 0xff; |
| 357 | S_SWAP(i, j); |
| 358 | *pos++ ^= S[(S[i] + S[j]) & 0xff]; |
| 359 | } |
| 360 | if (m->m_next == NULL) { |
| 361 | if (data_len != 0) { /* out of data */ |
| 362 | IEEE80211_DPRINTF(ctx->wc_ic, |
| 363 | IEEE80211_MSG_CRYPTO, |
| 364 | "[%s] out of data for WEP (data_len %zu)\n" , |
| 365 | ether_sprintf(mtod(m0, |
| 366 | struct ieee80211_frame *)->i_addr2), |
| 367 | data_len); |
| 368 | return 0; |
| 369 | } |
| 370 | break; |
| 371 | } |
| 372 | m = m->m_next; |
| 373 | pos = mtod(m, uint8_t *); |
| 374 | buflen = m->m_len; |
| 375 | } |
| 376 | crc = ~crc; |
| 377 | |
| 378 | /* Append little-endian CRC32 and encrypt it to produce ICV */ |
| 379 | icv[0] = crc; |
| 380 | icv[1] = crc >> 8; |
| 381 | icv[2] = crc >> 16; |
| 382 | icv[3] = crc >> 24; |
| 383 | for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) { |
| 384 | i = (i + 1) & 0xff; |
| 385 | j = (j + S[i]) & 0xff; |
| 386 | S_SWAP(i, j); |
| 387 | icv[k] ^= S[(S[i] + S[j]) & 0xff]; |
| 388 | } |
| 389 | return m_append(m0, IEEE80211_WEP_CRCLEN, icv); |
| 390 | #undef S_SWAP |
| 391 | } |
| 392 | |
| 393 | static int |
| 394 | wep_decrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen) |
| 395 | { |
| 396 | #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0) |
| 397 | struct wep_ctx *ctx = key->wk_private; |
| 398 | struct mbuf *m = m0; |
| 399 | u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE]; |
| 400 | uint8_t icv[IEEE80211_WEP_CRCLEN]; |
| 401 | uint32_t i, j, k, crc; |
| 402 | size_t buflen, data_len; |
| 403 | uint8_t S[256]; |
| 404 | uint8_t *pos; |
| 405 | u_int off, keylen; |
| 406 | |
| 407 | ctx->wc_ic->ic_stats.is_crypto_wep++; |
| 408 | |
| 409 | /* NB: this assumes the header was pulled up */ |
| 410 | memcpy(rc4key, mtod(m, u_int8_t *) + hdrlen, IEEE80211_WEP_IVLEN); |
| 411 | memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen); |
| 412 | |
| 413 | /* Setup RC4 state */ |
| 414 | for (i = 0; i < 256; i++) |
| 415 | S[i] = i; |
| 416 | j = 0; |
| 417 | keylen = key->wk_keylen + IEEE80211_WEP_IVLEN; |
| 418 | for (i = 0; i < 256; i++) { |
| 419 | j = (j + S[i] + rc4key[i % keylen]) & 0xff; |
| 420 | S_SWAP(i, j); |
| 421 | } |
| 422 | |
| 423 | off = hdrlen + wep.ic_header; |
| 424 | data_len = m->m_pkthdr.len - (off + wep.ic_trailer); |
| 425 | |
| 426 | /* Compute CRC32 over unencrypted data and apply RC4 to data */ |
| 427 | crc = ~0; |
| 428 | i = j = 0; |
| 429 | pos = mtod(m, uint8_t *) + off; |
| 430 | buflen = m->m_len - off; |
| 431 | for (;;) { |
| 432 | if (buflen > data_len) |
| 433 | buflen = data_len; |
| 434 | data_len -= buflen; |
| 435 | for (k = 0; k < buflen; k++) { |
| 436 | i = (i + 1) & 0xff; |
| 437 | j = (j + S[i]) & 0xff; |
| 438 | S_SWAP(i, j); |
| 439 | *pos ^= S[(S[i] + S[j]) & 0xff]; |
| 440 | crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8); |
| 441 | pos++; |
| 442 | } |
| 443 | m = m->m_next; |
| 444 | if (m == NULL) { |
| 445 | if (data_len != 0) { /* out of data */ |
| 446 | IEEE80211_DPRINTF(ctx->wc_ic, |
| 447 | IEEE80211_MSG_CRYPTO, |
| 448 | "[%s] out of data for WEP (data_len %zu)\n" , |
| 449 | ether_sprintf(mtod(m0, |
| 450 | struct ieee80211_frame *)->i_addr2), |
| 451 | data_len); |
| 452 | return 0; |
| 453 | } |
| 454 | break; |
| 455 | } |
| 456 | pos = mtod(m, uint8_t *); |
| 457 | buflen = m->m_len; |
| 458 | } |
| 459 | crc = ~crc; |
| 460 | |
| 461 | /* Encrypt little-endian CRC32 and verify that it matches with |
| 462 | * received ICV */ |
| 463 | icv[0] = crc; |
| 464 | icv[1] = crc >> 8; |
| 465 | icv[2] = crc >> 16; |
| 466 | icv[3] = crc >> 24; |
| 467 | for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) { |
| 468 | i = (i + 1) & 0xff; |
| 469 | j = (j + S[i]) & 0xff; |
| 470 | S_SWAP(i, j); |
| 471 | /* XXX assumes ICV is contiguous in mbuf */ |
| 472 | if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *pos++) { |
| 473 | /* ICV mismatch - drop frame */ |
| 474 | return 0; |
| 475 | } |
| 476 | } |
| 477 | return 1; |
| 478 | #undef S_SWAP |
| 479 | } |
| 480 | |
| 481 | IEEE80211_CRYPTO_SETUP(wep_register) |
| 482 | { |
| 483 | ieee80211_crypto_register(&wep); |
| 484 | } |
| 485 | |