Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/net80211/ieee80211_crypto_wep.c
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1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2002-2008 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 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include <sys/cdefs.h> 29 __FBSDID("$FreeBSD$"); 30 31 /* 32 * IEEE 802.11 WEP crypto support. 33 */ 34 #include "opt_wlan.h" 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/mbuf.h> 39 #include <sys/malloc.h> 40 #include <sys/kernel.h> 41 #include <sys/module.h> 42 #include <sys/endian.h> 43 44 #include <sys/socket.h> 45 46 #include <net/if.h> 47 #include <net/if_media.h> 48 #include <net/ethernet.h> 49 50 #include <net80211/ieee80211_var.h> 51 52 static void *wep_attach(struct ieee80211vap *, struct ieee80211_key *); 53 static void wep_detach(struct ieee80211_key *); 54 static int wep_setkey(struct ieee80211_key *); 55 static void wep_setiv(struct ieee80211_key *, uint8_t *); 56 static int wep_encap(struct ieee80211_key *, struct mbuf *); 57 static int wep_decap(struct ieee80211_key *, struct mbuf *, int); 58 static int wep_enmic(struct ieee80211_key *, struct mbuf *, int); 59 static int wep_demic(struct ieee80211_key *, struct mbuf *, int); 60 61 static const struct ieee80211_cipher wep = { 62 .ic_name = "WEP", 63 .ic_cipher = IEEE80211_CIPHER_WEP, 64 .ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN, 65 .ic_trailer = IEEE80211_WEP_CRCLEN, 66 .ic_miclen = 0, 67 .ic_attach = wep_attach, 68 .ic_detach = wep_detach, 69 .ic_setkey = wep_setkey, 70 .ic_setiv = wep_setiv, 71 .ic_encap = wep_encap, 72 .ic_decap = wep_decap, 73 .ic_enmic = wep_enmic, 74 .ic_demic = wep_demic, 75 }; 76 77 static int wep_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen); 78 static int wep_decrypt(struct ieee80211_key *, struct mbuf *, int hdrlen); 79 80 struct wep_ctx { 81 struct ieee80211vap *wc_vap; /* for diagnostics+statistics */ 82 struct ieee80211com *wc_ic; 83 uint32_t wc_iv; /* initial vector for crypto */ 84 }; 85 86 /* number of references from net80211 layer */ 87 static int nrefs = 0; 88 89 static void * 90 wep_attach(struct ieee80211vap *vap, struct ieee80211_key *k) 91 { 92 struct wep_ctx *ctx; 93 94 ctx = (struct wep_ctx *) IEEE80211_MALLOC(sizeof(struct wep_ctx), 95 M_80211_CRYPTO, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO); 96 if (ctx == NULL) { 97 vap->iv_stats.is_crypto_nomem++; 98 return NULL; 99 } 100 101 ctx->wc_vap = vap; 102 ctx->wc_ic = vap->iv_ic; 103 net80211_get_random_bytes(&ctx->wc_iv, sizeof(ctx->wc_iv)); 104 nrefs++; /* NB: we assume caller locking */ 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 IEEE80211_FREE(ctx, M_80211_CRYPTO); 114 KASSERT(nrefs > 0, ("imbalanced attach/detach")); 115 nrefs--; /* NB: we assume caller locking */ 116 } 117 118 static int 119 wep_setkey(struct ieee80211_key *k) 120 { 121 return k->wk_keylen >= 40/NBBY; 122 } 123 124 static void 125 wep_setiv(struct ieee80211_key *k, uint8_t *ivp) 126 { 127 struct wep_ctx *ctx = k->wk_private; 128 struct ieee80211vap *vap = ctx->wc_vap; 129 uint32_t iv; 130 uint8_t keyid; 131 132 keyid = ieee80211_crypto_get_keyid(vap, k) << 6; 133 134 /* 135 * XXX 136 * IV must not duplicate during the lifetime of the key. 137 * But no mechanism to renew keys is defined in IEEE 802.11 138 * for WEP. And the IV may be duplicated at other stations 139 * because the session key itself is shared. So we use a 140 * pseudo random IV for now, though it is not the right way. 141 * 142 * NB: Rather than use a strictly random IV we select a 143 * random one to start and then increment the value for 144 * each frame. This is an explicit tradeoff between 145 * overhead and security. Given the basic insecurity of 146 * WEP this seems worthwhile. 147 */ 148 149 /* 150 * Skip 'bad' IVs from Fluhrer/Mantin/Shamir: 151 * (B, 255, N) with 3 <= B < 16 and 0 <= N <= 255 152 */ 153 iv = ctx->wc_iv; 154 if ((iv & 0xff00) == 0xff00) { 155 int B = (iv & 0xff0000) >> 16; 156 if (3 <= B && B < 16) 157 iv += 0x0100; 158 } 159 ctx->wc_iv = iv + 1; 160 161 /* 162 * NB: Preserve byte order of IV for packet 163 * sniffers; it doesn't matter otherwise. 164 */ 165 #if _BYTE_ORDER == _BIG_ENDIAN 166 ivp[0] = iv >> 0; 167 ivp[1] = iv >> 8; 168 ivp[2] = iv >> 16; 169 #else 170 ivp[2] = iv >> 0; 171 ivp[1] = iv >> 8; 172 ivp[0] = iv >> 16; 173 #endif 174 ivp[3] = keyid; 175 } 176 177 /* 178 * Add privacy headers appropriate for the specified key. 179 */ 180 static int 181 wep_encap(struct ieee80211_key *k, struct mbuf *m) 182 { 183 struct wep_ctx *ctx = k->wk_private; 184 struct ieee80211com *ic = ctx->wc_ic; 185 struct ieee80211_frame *wh; 186 uint8_t *ivp; 187 int hdrlen; 188 int is_mgmt; 189 190 hdrlen = ieee80211_hdrspace(ic, mtod(m, void *)); 191 wh = mtod(m, struct ieee80211_frame *); 192 is_mgmt = IEEE80211_IS_MGMT(wh); 193 194 /* 195 * Check to see if IV is required. 196 */ 197 if (is_mgmt && (k->wk_flags & IEEE80211_KEY_NOIVMGT)) 198 return 1; 199 if ((! is_mgmt) && (k->wk_flags & IEEE80211_KEY_NOIV)) 200 return 1; 201 202 /* 203 * Copy down 802.11 header and add the IV + KeyID. 204 */ 205 M_PREPEND(m, wep.ic_header, IEEE80211_M_NOWAIT); 206 if (m == NULL) 207 return 0; 208 ivp = mtod(m, uint8_t *); 209 ovbcopy(ivp + wep.ic_header, ivp, hdrlen); 210 ivp += hdrlen; 211 212 wep_setiv(k, ivp); 213 214 /* 215 * Finally, do software encrypt if needed. 216 */ 217 if ((k->wk_flags & IEEE80211_KEY_SWENCRYPT) && 218 !wep_encrypt(k, m, hdrlen)) 219 return 0; 220 221 return 1; 222 } 223 224 /* 225 * Add MIC to the frame as needed. 226 */ 227 static int 228 wep_enmic(struct ieee80211_key *k, struct mbuf *m, int force) 229 { 230 231 return 1; 232 } 233 234 /* 235 * Validate and strip privacy headers (and trailer) for a 236 * received frame. If necessary, decrypt the frame using 237 * the specified key. 238 */ 239 static int 240 wep_decap(struct ieee80211_key *k, struct mbuf *m, int hdrlen) 241 { 242 struct wep_ctx *ctx = k->wk_private; 243 struct ieee80211vap *vap = ctx->wc_vap; 244 const struct ieee80211_rx_stats *rxs; 245 246 rxs = ieee80211_get_rx_params_ptr(m); 247 248 if ((rxs != NULL) && (rxs->c_pktflags & IEEE80211_RX_F_IV_STRIP)) 249 goto finish; 250 251 /* 252 * Check if the device handled the decrypt in hardware. 253 * If so we just strip the header; otherwise we need to 254 * handle the decrypt in software. 255 */ 256 if ((k->wk_flags & IEEE80211_KEY_SWDECRYPT) && 257 !wep_decrypt(k, m, hdrlen)) { 258 #ifdef IEEE80211_DEBUG 259 struct ieee80211_frame *wh; 260 261 wh = mtod(m, struct ieee80211_frame *); 262 #endif 263 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, wh->i_addr2, 264 "%s", "WEP ICV mismatch on decrypt"); 265 vap->iv_stats.is_rx_wepfail++; 266 return 0; 267 } 268 269 /* 270 * Copy up 802.11 header and strip crypto bits. 271 */ 272 ovbcopy(mtod(m, void *), mtod(m, uint8_t *) + wep.ic_header, hdrlen); 273 m_adj(m, wep.ic_header); 274 275 finish: 276 /* XXX TODO: do we have to strip this for offload devices? */ 277 m_adj(m, -wep.ic_trailer); 278 279 return 1; 280 } 281 282 /* 283 * Verify and strip MIC from the frame. 284 */ 285 static int 286 wep_demic(struct ieee80211_key *k, struct mbuf *skb, int force) 287 { 288 return 1; 289 } 290 291 static const uint32_t crc32_table[256] = { 292 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L, 293 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L, 294 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L, 295 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL, 296 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L, 297 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L, 298 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L, 299 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL, 300 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L, 301 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL, 302 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, 303 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L, 304 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L, 305 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL, 306 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL, 307 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L, 308 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL, 309 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L, 310 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L, 311 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L, 312 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL, 313 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L, 314 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L, 315 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL, 316 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L, 317 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L, 318 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L, 319 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L, 320 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L, 321 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL, 322 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL, 323 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L, 324 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L, 325 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL, 326 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL, 327 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L, 328 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL, 329 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L, 330 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL, 331 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L, 332 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL, 333 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L, 334 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L, 335 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL, 336 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L, 337 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L, 338 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, 339 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L, 340 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L, 341 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L, 342 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL, 343 0x2d02ef8dL 344 }; 345 346 static int 347 wep_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen) 348 { 349 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0) 350 struct wep_ctx *ctx = key->wk_private; 351 struct ieee80211vap *vap = ctx->wc_vap; 352 struct mbuf *m = m0; 353 uint8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE]; 354 uint8_t icv[IEEE80211_WEP_CRCLEN]; 355 uint32_t i, j, k, crc; 356 size_t buflen, data_len; 357 uint8_t S[256]; 358 uint8_t *pos; 359 u_int off, keylen; 360 361 vap->iv_stats.is_crypto_wep++; 362 363 /* NB: this assumes the header was pulled up */ 364 memcpy(rc4key, mtod(m, uint8_t *) + hdrlen, IEEE80211_WEP_IVLEN); 365 memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen); 366 367 /* Setup RC4 state */ 368 for (i = 0; i < 256; i++) 369 S[i] = i; 370 j = 0; 371 keylen = key->wk_keylen + IEEE80211_WEP_IVLEN; 372 for (i = 0; i < 256; i++) { 373 j = (j + S[i] + rc4key[i % keylen]) & 0xff; 374 S_SWAP(i, j); 375 } 376 377 off = hdrlen + wep.ic_header; 378 data_len = m->m_pkthdr.len - off; 379 380 /* Compute CRC32 over unencrypted data and apply RC4 to data */ 381 crc = ~0; 382 i = j = 0; 383 pos = mtod(m, uint8_t *) + off; 384 buflen = m->m_len - off; 385 for (;;) { 386 if (buflen > data_len) 387 buflen = data_len; 388 data_len -= buflen; 389 for (k = 0; k < buflen; k++) { 390 crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8); 391 i = (i + 1) & 0xff; 392 j = (j + S[i]) & 0xff; 393 S_SWAP(i, j); 394 *pos++ ^= S[(S[i] + S[j]) & 0xff]; 395 } 396 if (m->m_next == NULL) { 397 if (data_len != 0) { /* out of data */ 398 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, 399 ether_sprintf(mtod(m0, 400 struct ieee80211_frame *)->i_addr2), 401 "out of data for WEP (data_len %zu)", 402 data_len); 403 /* XXX stat */ 404 return 0; 405 } 406 break; 407 } 408 m = m->m_next; 409 pos = mtod(m, uint8_t *); 410 buflen = m->m_len; 411 } 412 crc = ~crc; 413 414 /* Append little-endian CRC32 and encrypt it to produce ICV */ 415 icv[0] = crc; 416 icv[1] = crc >> 8; 417 icv[2] = crc >> 16; 418 icv[3] = crc >> 24; 419 for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) { 420 i = (i + 1) & 0xff; 421 j = (j + S[i]) & 0xff; 422 S_SWAP(i, j); 423 icv[k] ^= S[(S[i] + S[j]) & 0xff]; 424 } 425 return m_append(m0, IEEE80211_WEP_CRCLEN, icv); 426 #undef S_SWAP 427 } 428 429 static int 430 wep_decrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen) 431 { 432 #define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0) 433 struct wep_ctx *ctx = key->wk_private; 434 struct ieee80211vap *vap = ctx->wc_vap; 435 struct mbuf *m = m0; 436 uint8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE]; 437 uint8_t icv[IEEE80211_WEP_CRCLEN]; 438 uint32_t i, j, k, crc; 439 size_t buflen, data_len; 440 uint8_t S[256]; 441 uint8_t *pos; 442 u_int off, keylen; 443 444 vap->iv_stats.is_crypto_wep++; 445 446 /* NB: this assumes the header was pulled up */ 447 memcpy(rc4key, mtod(m, uint8_t *) + hdrlen, IEEE80211_WEP_IVLEN); 448 memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen); 449 450 /* Setup RC4 state */ 451 for (i = 0; i < 256; i++) 452 S[i] = i; 453 j = 0; 454 keylen = key->wk_keylen + IEEE80211_WEP_IVLEN; 455 for (i = 0; i < 256; i++) { 456 j = (j + S[i] + rc4key[i % keylen]) & 0xff; 457 S_SWAP(i, j); 458 } 459 460 off = hdrlen + wep.ic_header; 461 data_len = m->m_pkthdr.len - (off + wep.ic_trailer); 462 463 /* Compute CRC32 over unencrypted data and apply RC4 to data */ 464 crc = ~0; 465 i = j = 0; 466 pos = mtod(m, uint8_t *) + off; 467 buflen = m->m_len - off; 468 for (;;) { 469 if (buflen > data_len) 470 buflen = data_len; 471 data_len -= buflen; 472 for (k = 0; k < buflen; k++) { 473 i = (i + 1) & 0xff; 474 j = (j + S[i]) & 0xff; 475 S_SWAP(i, j); 476 *pos ^= S[(S[i] + S[j]) & 0xff]; 477 crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8); 478 pos++; 479 } 480 m = m->m_next; 481 if (m == NULL) { 482 if (data_len != 0) { /* out of data */ 483 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO, 484 mtod(m0, struct ieee80211_frame *)->i_addr2, 485 "out of data for WEP (data_len %zu)", 486 data_len); 487 return 0; 488 } 489 break; 490 } 491 pos = mtod(m, uint8_t *); 492 buflen = m->m_len; 493 } 494 crc = ~crc; 495 496 /* Encrypt little-endian CRC32 and verify that it matches with 497 * received ICV */ 498 icv[0] = crc; 499 icv[1] = crc >> 8; 500 icv[2] = crc >> 16; 501 icv[3] = crc >> 24; 502 for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) { 503 i = (i + 1) & 0xff; 504 j = (j + S[i]) & 0xff; 505 S_SWAP(i, j); 506 /* XXX assumes ICV is contiguous in mbuf */ 507 if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *pos++) { 508 /* ICV mismatch - drop frame */ 509 return 0; 510 } 511 } 512 return 1; 513 #undef S_SWAP 514 } 515 516 /* 517 * Module glue. 518 */ 519 IEEE80211_CRYPTO_MODULE(wep, 1);
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