diff options
Diffstat (limited to 'sys/net80211/ieee80211_crypto_wep.c')
| -rw-r--r-- | sys/net80211/ieee80211_crypto_wep.c | 499 |
1 files changed, 499 insertions, 0 deletions
diff --git a/sys/net80211/ieee80211_crypto_wep.c b/sys/net80211/ieee80211_crypto_wep.c new file mode 100644 index 0000000..2edb5bb --- /dev/null +++ b/sys/net80211/ieee80211_crypto_wep.c @@ -0,0 +1,499 @@ +/*- + * Copyright (c) 2002-2004 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("$FreeBSD$"); + +/* + * IEEE 802.11 WEP crypto support. + */ +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/mbuf.h> +#include <sys/malloc.h> +#include <sys/kernel.h> +#include <sys/module.h> +#include <sys/endian.h> + +#include <sys/socket.h> + +#include <net/if.h> +#include <net/if_media.h> +#include <net/ethernet.h> + +#include <net80211/ieee80211_var.h> + +static void *wep_attach(struct ieee80211com *, struct ieee80211_key *); +static void wep_detach(struct ieee80211_key *); +static int wep_setkey(struct ieee80211_key *); +static int wep_encap(struct ieee80211_key *, struct mbuf *, u_int8_t keyid); +static int wep_decap(struct ieee80211_key *, struct mbuf *); +static int wep_enmic(struct ieee80211_key *, struct mbuf *); +static int wep_demic(struct ieee80211_key *, struct mbuf *); + +static const struct ieee80211_cipher wep = { + .ic_name = "WEP", + .ic_cipher = IEEE80211_CIPHER_WEP, + .ic_header = IEEE80211_WEP_IVLEN + IEEE80211_WEP_KIDLEN, + .ic_trailer = IEEE80211_WEP_CRCLEN, + .ic_miclen = 0, + .ic_attach = wep_attach, + .ic_detach = wep_detach, + .ic_setkey = wep_setkey, + .ic_encap = wep_encap, + .ic_decap = wep_decap, + .ic_enmic = wep_enmic, + .ic_demic = wep_demic, +}; + +static int wep_encrypt(struct ieee80211_key *, struct mbuf *, int hdrlen); +static int wep_decrypt(struct ieee80211_key *, struct mbuf *, int hdrlen); + +struct wep_ctx { + struct ieee80211com *wc_ic; /* for diagnostics */ + u_int32_t wc_iv; /* initial vector for crypto */ +}; + +static void * +wep_attach(struct ieee80211com *ic, struct ieee80211_key *k) +{ + struct wep_ctx *ctx; + + MALLOC(ctx, struct wep_ctx *, sizeof(struct wep_ctx), + M_DEVBUF, M_NOWAIT | M_ZERO); + if (ctx == NULL) { + ic->ic_stats.is_crypto_nomem++; + return NULL; + } + + ctx->wc_ic = ic; + get_random_bytes(&ctx->wc_iv, sizeof(ctx->wc_iv)); + return ctx; +} + +static void +wep_detach(struct ieee80211_key *k) +{ + struct wep_ctx *ctx = k->wk_private; + + FREE(ctx, M_DEVBUF); +} + +static int +wep_setkey(struct ieee80211_key *k) +{ + return k->wk_keylen >= 40/NBBY; +} + +/* + * Add privacy headers appropriate for the specified key. + */ +static int +wep_encap(struct ieee80211_key *k, struct mbuf *m, u_int8_t keyid) +{ + struct wep_ctx *ctx = k->wk_private; + u_int32_t iv; + u_int8_t *ivp; + int hdrlen; + + hdrlen = ieee80211_hdrsize(mtod(m, void *)); + + /* + * Copy down 802.11 header and add the IV + KeyID. + */ + M_PREPEND(m, wep.ic_header, M_NOWAIT); + if (m == NULL) + return 0; + ivp = mtod(m, u_int8_t *); + ovbcopy(ivp + wep.ic_header, ivp, hdrlen); + ivp += hdrlen; + + /* + * XXX + * IV must not duplicate during the lifetime of the key. + * But no mechanism to renew keys is defined in IEEE 802.11 + * for WEP. And the IV may be duplicated at other stations + * because the session key itself is shared. So we use a + * pseudo random IV for now, though it is not the right way. + * + * NB: Rather than use a strictly random IV we select a + * random one to start and then increment the value for + * each frame. This is an explicit tradeoff between + * overhead and security. Given the basic insecurity of + * WEP this seems worthwhile. + */ + + /* + * Skip 'bad' IVs from Fluhrer/Mantin/Shamir: + * (B, 255, N) with 3 <= B < 16 and 0 <= N <= 255 + */ + iv = ctx->wc_iv; + if ((iv & 0xff00) == 0xff00) { + int B = (iv & 0xff0000) >> 16; + if (3 <= B && B < 16) + iv += 0x0100; + } + ctx->wc_iv = iv + 1; + + /* + * NB: Preserve byte order of IV for packet + * sniffers; it doesn't matter otherwise. + */ +#if _BYTE_ORDER == _BIG_ENDIAN + ivp[0] = iv >> 0; + ivp[1] = iv >> 8; + ivp[2] = iv >> 16; +#else + ivp[2] = iv >> 0; + ivp[1] = iv >> 8; + ivp[0] = iv >> 16; +#endif + ivp[3] = keyid; + + /* + * Finally, do software encrypt if neeed. + */ + if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) && + !wep_encrypt(k, m, hdrlen)) + return 0; + + return 1; +} + +/* + * Add MIC to the frame as needed. + */ +static int +wep_enmic(struct ieee80211_key *k, struct mbuf *m) +{ + + return 1; +} + +/* + * Validate and strip privacy headers (and trailer) for a + * received frame. If necessary, decrypt the frame using + * the specified key. + */ +static int +wep_decap(struct ieee80211_key *k, struct mbuf *m) +{ + struct wep_ctx *ctx = k->wk_private; + struct ieee80211_frame *wh; + int hdrlen; + + wh = mtod(m, struct ieee80211_frame *); + hdrlen = ieee80211_hdrsize(wh); + + /* + * 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. + */ + if ((k->wk_flags & IEEE80211_KEY_SWCRYPT) && + !wep_decrypt(k, m, hdrlen)) { + IEEE80211_DPRINTF(ctx->wc_ic, IEEE80211_MSG_CRYPTO, + "[%s] WEP ICV mismatch on decrypt\n", + ether_sprintf(wh->i_addr2)); + ctx->wc_ic->ic_stats.is_rx_wepfail++; + return 0; + } + + /* + * Copy up 802.11 header and strip crypto bits. + */ + ovbcopy(mtod(m, void *), mtod(m, u_int8_t *) + wep.ic_header, hdrlen); + m_adj(m, wep.ic_header); + m_adj(m, -wep.ic_trailer); + + return 1; +} + +/* + * Verify and strip MIC from the frame. + */ +static int +wep_demic(struct ieee80211_key *k, struct mbuf *skb) +{ + return 1; +} + +static const uint32_t crc32_table[256] = { + 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L, + 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L, + 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L, + 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL, + 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L, + 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L, + 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L, + 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL, + 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L, + 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL, + 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, + 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L, + 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L, + 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL, + 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL, + 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L, + 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL, + 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L, + 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L, + 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L, + 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL, + 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L, + 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L, + 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL, + 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L, + 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L, + 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L, + 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L, + 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L, + 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL, + 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL, + 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L, + 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L, + 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL, + 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL, + 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L, + 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL, + 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L, + 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL, + 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L, + 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL, + 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L, + 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L, + 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL, + 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L, + 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L, + 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, + 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L, + 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L, + 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L, + 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL, + 0x2d02ef8dL +}; + +static int +wep_encrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen) +{ +#define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0) + struct wep_ctx *ctx = key->wk_private; + struct mbuf *m = m0; + u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE]; + uint8_t icv[IEEE80211_WEP_CRCLEN]; + uint32_t i, j, k, crc; + size_t buflen, data_len; + uint8_t S[256]; + uint8_t *pos; + u_int off, keylen; + + ctx->wc_ic->ic_stats.is_crypto_wep++; + + /* NB: this assumes the header was pulled up */ + memcpy(rc4key, mtod(m, u_int8_t *) + hdrlen, IEEE80211_WEP_IVLEN); + memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen); + + /* Setup RC4 state */ + for (i = 0; i < 256; i++) + S[i] = i; + j = 0; + keylen = key->wk_keylen + IEEE80211_WEP_IVLEN; + for (i = 0; i < 256; i++) { + j = (j + S[i] + rc4key[i % keylen]) & 0xff; + S_SWAP(i, j); + } + + off = hdrlen + wep.ic_header; + data_len = m->m_pkthdr.len - off; + + /* Compute CRC32 over unencrypted data and apply RC4 to data */ + crc = ~0; + i = j = 0; + pos = mtod(m, uint8_t *) + off; + buflen = m->m_len - off; + for (;;) { + if (buflen > data_len) + buflen = data_len; + data_len -= buflen; + for (k = 0; k < buflen; k++) { + crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8); + i = (i + 1) & 0xff; + j = (j + S[i]) & 0xff; + S_SWAP(i, j); + *pos++ ^= S[(S[i] + S[j]) & 0xff]; + } + if (m->m_next == NULL) { + if (data_len != 0) { /* out of data */ + IEEE80211_DPRINTF(ctx->wc_ic, + IEEE80211_MSG_CRYPTO, + "[%s] out of data for WEP (data_len %u)\n", + ether_sprintf(mtod(m0, + struct ieee80211_frame *)->i_addr2), + data_len); + return 0; + } + break; + } + m = m->m_next; + pos = mtod(m, uint8_t *); + buflen = m->m_len; + } + crc = ~crc; + + /* Append little-endian CRC32 and encrypt it to produce ICV */ + icv[0] = crc; + icv[1] = crc >> 8; + icv[2] = crc >> 16; + icv[3] = crc >> 24; + for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) { + i = (i + 1) & 0xff; + j = (j + S[i]) & 0xff; + S_SWAP(i, j); + icv[k] ^= S[(S[i] + S[j]) & 0xff]; + } + return m_append(m0, IEEE80211_WEP_CRCLEN, icv); +#undef S_SWAP +} + +static int +wep_decrypt(struct ieee80211_key *key, struct mbuf *m0, int hdrlen) +{ +#define S_SWAP(a,b) do { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; } while(0) + struct wep_ctx *ctx = key->wk_private; + struct mbuf *m = m0; + u_int8_t rc4key[IEEE80211_WEP_IVLEN + IEEE80211_KEYBUF_SIZE]; + uint8_t icv[IEEE80211_WEP_CRCLEN]; + uint32_t i, j, k, crc; + size_t buflen, data_len; + uint8_t S[256]; + uint8_t *pos; + u_int off, keylen; + + ctx->wc_ic->ic_stats.is_crypto_wep++; + + /* NB: this assumes the header was pulled up */ + memcpy(rc4key, mtod(m, u_int8_t *) + hdrlen, IEEE80211_WEP_IVLEN); + memcpy(rc4key + IEEE80211_WEP_IVLEN, key->wk_key, key->wk_keylen); + + /* Setup RC4 state */ + for (i = 0; i < 256; i++) + S[i] = i; + j = 0; + keylen = key->wk_keylen + IEEE80211_WEP_IVLEN; + for (i = 0; i < 256; i++) { + j = (j + S[i] + rc4key[i % keylen]) & 0xff; + S_SWAP(i, j); + } + + off = hdrlen + wep.ic_header; + data_len = m->m_pkthdr.len - (off + wep.ic_trailer), + + /* Compute CRC32 over unencrypted data and apply RC4 to data */ + crc = ~0; + i = j = 0; + pos = mtod(m, uint8_t *) + off; + buflen = m->m_len - off; + for (;;) { + if (buflen > data_len) + buflen = data_len; + data_len -= buflen; + for (k = 0; k < buflen; k++) { + i = (i + 1) & 0xff; + j = (j + S[i]) & 0xff; + S_SWAP(i, j); + *pos ^= S[(S[i] + S[j]) & 0xff]; + crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8); + pos++; + } + m = m->m_next; + if (m == NULL) { + if (data_len != 0) { /* out of data */ + IEEE80211_DPRINTF(ctx->wc_ic, + IEEE80211_MSG_CRYPTO, + "[%s] out of data for WEP (data_len %u)\n", + ether_sprintf(mtod(m0, + struct ieee80211_frame *)->i_addr2), + data_len); + return 0; + } + break; + } + pos = mtod(m, uint8_t *); + buflen = m->m_len; + } + crc = ~crc; + + /* Encrypt little-endian CRC32 and verify that it matches with + * received ICV */ + icv[0] = crc; + icv[1] = crc >> 8; + icv[2] = crc >> 16; + icv[3] = crc >> 24; + for (k = 0; k < IEEE80211_WEP_CRCLEN; k++) { + i = (i + 1) & 0xff; + j = (j + S[i]) & 0xff; + S_SWAP(i, j); + /* XXX assumes ICV is contiguous in mbuf */ + if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *pos++) { + /* ICV mismatch - drop frame */ + return 0; + } + } + return 1; +#undef S_SWAP +} + +/* + * Module glue. + */ +static int +wep_modevent(module_t mod, int type, void *unused) +{ + switch (type) { + case MOD_LOAD: + ieee80211_crypto_register(&wep); + return 0; + case MOD_UNLOAD: + ieee80211_crypto_unregister(&wep); + return 0; + } + return EINVAL; +} + +static moduledata_t wep_mod = { + "wlan_wep", + wep_modevent, + 0 +}; +DECLARE_MODULE(wlan_wep, wep_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST); +MODULE_VERSION(wlan_wep, 1); +MODULE_DEPEND(wlan_wep, wlan, 1, 1, 1); +MODULE_DEPEND(wlan_wep, rc4, 1, 1, 1); |
