/* * Copyright (c) 2009 Joshua Oreman . * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of the * License, or any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301, USA. */ FILE_LICENCE ( GPL2_OR_LATER ); #include #include #include #include #include #include #include #include #include #include #include /** @file * * Backend for WPA using the TKIP encryption standard. */ /** Context for one direction of TKIP, either encryption or decryption */ struct tkip_dir_ctx { /** High 32 bits of last sequence counter value used */ u32 tsc_hi; /** Low 32 bits of last sequence counter value used */ u16 tsc_lo; /** MAC address used to derive TTAK */ u8 mac[ETH_ALEN]; /** If TRUE, TTAK is valid */ u16 ttak_ok; /** TKIP-mixed transmit address and key, depends on tsc_hi and MAC */ u16 ttak[5]; }; /** Context for TKIP encryption and decryption */ struct tkip_ctx { /** Temporal key to use */ struct tkip_tk tk; /** State for encryption */ struct tkip_dir_ctx enc; /** State for decryption */ struct tkip_dir_ctx dec; }; /** Header structure at the beginning of TKIP frame data */ struct tkip_head { u8 tsc1; /**< High byte of low 16 bits of TSC */ u8 seed1; /**< Second byte of WEP seed */ u8 tsc0; /**< Low byte of TSC */ u8 kid; /**< Key ID and ExtIV byte */ u32 tsc_hi; /**< High 32 bits of TSC, as an ExtIV */ } __attribute__ (( packed )); /** TKIP header overhead (IV + KID + ExtIV) */ #define TKIP_HEAD_LEN 8 /** TKIP trailer overhead (MIC + ICV) [assumes unfragmented] */ #define TKIP_FOOT_LEN 12 /** TKIP MIC length */ #define TKIP_MIC_LEN 8 /** TKIP ICV length */ #define TKIP_ICV_LEN 4 /** TKIP S-box */ static const u16 Sbox[256] = { 0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154, 0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A, 0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B, 0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B, 0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F, 0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F, 0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5, 0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F, 0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB, 0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397, 0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED, 0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A, 0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194, 0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3, 0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104, 0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D, 0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39, 0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695, 0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83, 0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76, 0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4, 0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B, 0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0, 0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018, 0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751, 0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85, 0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12, 0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9, 0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7, 0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A, 0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8, 0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A, }; /** * Perform S-box mapping on a 16-bit value * * @v v Value to perform S-box mapping on * @ret Sv S-box mapped value */ static inline u16 S ( u16 v ) { return Sbox[v & 0xFF] ^ bswap_16 ( Sbox[v >> 8] ); } /** * Rotate 16-bit value right * * @v v Value to rotate * @v bits Number of bits to rotate by * @ret rotv Rotated value */ static inline u16 ror16 ( u16 v, int bits ) { return ( v >> bits ) | ( v << ( 16 - bits ) ); } /** * Rotate 32-bit value right * * @v v Value to rotate * @v bits Number of bits to rotate by * @ret rotv Rotated value */ static inline u32 ror32 ( u32 v, int bits ) { return ( v >> bits ) | ( v << ( 32 - bits ) ); } /** * Rotate 32-bit value left * * @v v Value to rotate * @v bits Number of bits to rotate by * @ret rotv Rotated value */ static inline u32 rol32 ( u32 v, int bits ) { return ( v << bits ) | ( v >> ( 32 - bits ) ); } /** * Initialise TKIP state and install key * * @v crypto TKIP cryptosystem structure * @v key Pointer to tkip_tk to install * @v keylen Length of key (32 bytes) * @v rsc Initial receive sequence counter */ static int tkip_init ( struct net80211_crypto *crypto, const void *key, int keylen, const void *rsc ) { struct tkip_ctx *ctx = crypto->priv; const u8 *rscb = rsc; if ( keylen != sizeof ( ctx->tk ) ) return -EINVAL; if ( rscb ) { ctx->dec.tsc_lo = ( rscb[1] << 8 ) | rscb[0]; ctx->dec.tsc_hi = ( ( rscb[5] << 24 ) | ( rscb[4] << 16 ) | ( rscb[3] << 8 ) | rscb[2] ); } memcpy ( &ctx->tk, key, sizeof ( ctx->tk ) ); return 0; } /** * Perform TKIP key mixing, phase 1 * * @v dctx TKIP directional context * @v tk TKIP temporal key * @v mac MAC address of transmitter * * This recomputes the TTAK in @a dctx if necessary, and sets * @c dctx->ttak_ok. */ static void tkip_mix_1 ( struct tkip_dir_ctx *dctx, struct tkip_tk *tk, u8 *mac ) { int i, j; if ( dctx->ttak_ok && ! memcmp ( mac, dctx->mac, ETH_ALEN ) ) return; memcpy ( dctx->mac, mac, ETH_ALEN ); dctx->ttak[0] = dctx->tsc_hi & 0xFFFF; dctx->ttak[1] = dctx->tsc_hi >> 16; dctx->ttak[2] = ( mac[1] << 8 ) | mac[0]; dctx->ttak[3] = ( mac[3] << 8 ) | mac[2]; dctx->ttak[4] = ( mac[5] << 8 ) | mac[4]; for ( i = 0; i < 8; i++ ) { j = 2 * ( i & 1 ); dctx->ttak[0] += S ( dctx->ttak[4] ^ ( ( tk->key[1 + j] << 8 ) | tk->key[0 + j] ) ); dctx->ttak[1] += S ( dctx->ttak[0] ^ ( ( tk->key[5 + j] << 8 ) | tk->key[4 + j] ) ); dctx->ttak[2] += S ( dctx->ttak[1] ^ ( ( tk->key[9 + j] << 8 ) | tk->key[8 + j] ) ); dctx->ttak[3] += S ( dctx->ttak[2] ^ ( ( tk->key[13+ j] << 8 ) | tk->key[12+ j] ) ); dctx->ttak[4] += S ( dctx->ttak[3] ^ ( ( tk->key[1 + j] << 8 ) | tk->key[0 + j] ) ) + i; } dctx->ttak_ok = 1; } /** * Perform TKIP key mixing, phase 2 * * @v dctx TKIP directional context * @v tk TKIP temporal key * @ret key ARC4 key, 16 bytes long */ static void tkip_mix_2 ( struct tkip_dir_ctx *dctx, struct tkip_tk *tk, void *key ) { u8 *kb = key; u16 ppk[6]; int i; memcpy ( ppk, dctx->ttak, sizeof ( dctx->ttak ) ); ppk[5] = dctx->ttak[4] + dctx->tsc_lo; ppk[0] += S ( ppk[5] ^ ( ( tk->key[1] << 8 ) | tk->key[0] ) ); ppk[1] += S ( ppk[0] ^ ( ( tk->key[3] << 8 ) | tk->key[2] ) ); ppk[2] += S ( ppk[1] ^ ( ( tk->key[5] << 8 ) | tk->key[4] ) ); ppk[3] += S ( ppk[2] ^ ( ( tk->key[7] << 8 ) | tk->key[6] ) ); ppk[4] += S ( ppk[3] ^ ( ( tk->key[9] << 8 ) | tk->key[8] ) ); ppk[5] += S ( ppk[4] ^ ( ( tk->key[11] << 8 ) | tk->key[10] ) ); ppk[0] += ror16 ( ppk[5] ^ ( ( tk->key[13] << 8 ) | tk->key[12] ), 1 ); ppk[1] += ror16 ( ppk[0] ^ ( ( tk->key[15] << 8 ) | tk->key[14] ), 1 ); ppk[2] += ror16 ( ppk[1], 1 ); ppk[3] += ror16 ( ppk[2], 1 ); ppk[4] += ror16 ( ppk[3], 1 ); ppk[5] += ror16 ( ppk[4], 1 ); kb[0] = dctx->tsc_lo >> 8; kb[1] = ( ( dctx->tsc_lo >> 8 ) | 0x20 ) & 0x7F; kb[2] = dctx->tsc_lo & 0xFF; kb[3] = ( ( ppk[5] ^ ( ( tk->key[1] << 8 ) | tk->key[0] ) ) >> 1 ) & 0xFF; for ( i = 0; i < 6; i++ ) { kb[4 + 2*i] = ppk[i] & 0xFF; kb[5 + 2*i] = ppk[i] >> 8; } } /** * Update Michael message integrity code based on next 32-bit word of data * * @v V Michael code state (two 32-bit words) * @v word Next 32-bit word of data */ static void tkip_feed_michael ( u32 *V, u32 word ) { V[0] ^= word; V[1] ^= rol32 ( V[0], 17 ); V[0] += V[1]; V[1] ^= ( ( V[0] & 0xFF00FF00 ) >> 8 ) | ( ( V[0] & 0x00FF00FF ) << 8 ); V[0] += V[1]; V[1] ^= rol32 ( V[0], 3 ); V[0] += V[1]; V[1] ^= ror32 ( V[0], 2 ); V[0] += V[1]; } /** * Calculate Michael message integrity code * * @v key MIC key to use (8 bytes) * @v da Destination link-layer address * @v sa Source link-layer address * @v data Start of data to calculate over * @v len Length of header + data * @ret mic Calculated Michael MIC (8 bytes) */ static void tkip_michael ( const void *key, const void *da, const void *sa, const void *data, size_t len, void *mic ) { u32 V[2]; /* V[0] = "l", V[1] = "r" in 802.11 */ union { u8 byte[12]; u32 word[3]; } cap; const u8 *ptr = data; const u8 *end = ptr + len; int i; memcpy ( V, key, sizeof ( V ) ); V[0] = le32_to_cpu ( V[0] ); V[1] = le32_to_cpu ( V[1] ); /* Feed in header (we assume non-QoS, so Priority = 0) */ memcpy ( &cap.byte[0], da, ETH_ALEN ); memcpy ( &cap.byte[6], sa, ETH_ALEN ); tkip_feed_michael ( V, le32_to_cpu ( cap.word[0] ) ); tkip_feed_michael ( V, le32_to_cpu ( cap.word[1] ) ); tkip_feed_michael ( V, le32_to_cpu ( cap.word[2] ) ); tkip_feed_michael ( V, 0 ); /* Feed in data */ while ( ptr + 4 <= end ) { tkip_feed_michael ( V, le32_to_cpu ( *( u32 * ) ptr ) ); ptr += 4; } /* Add unaligned part and padding */ for ( i = 0; ptr < end; i++ ) cap.byte[i] = *ptr++; cap.byte[i++] = 0x5a; for ( ; i < 8; i++ ) cap.byte[i] = 0; /* Feed in padding */ tkip_feed_michael ( V, le32_to_cpu ( cap.word[0] ) ); tkip_feed_michael ( V, le32_to_cpu ( cap.word[1] ) ); /* Output MIC */ V[0] = cpu_to_le32 ( V[0] ); V[1] = cpu_to_le32 ( V[1] ); memcpy ( mic, V, sizeof ( V ) ); } /** * Encrypt a packet using TKIP * * @v crypto TKIP cryptosystem * @v iob I/O buffer containing cleartext packet * @ret eiob I/O buffer containing encrypted packet */ static struct io_buffer * tkip_encrypt ( struct net80211_crypto *crypto, struct io_buffer *iob ) { struct tkip_ctx *ctx = crypto->priv; struct ieee80211_frame *hdr = iob->data; struct io_buffer *eiob; struct arc4_ctx arc4; u8 key[16]; struct tkip_head head; u8 mic[8]; u32 icv; const int hdrlen = IEEE80211_TYP_FRAME_HEADER_LEN; int datalen = iob_len ( iob ) - hdrlen; ctx->enc.tsc_lo++; if ( ctx->enc.tsc_lo == 0 ) { ctx->enc.tsc_hi++; ctx->enc.ttak_ok = 0; } tkip_mix_1 ( &ctx->enc, &ctx->tk, hdr->addr2 ); tkip_mix_2 ( &ctx->enc, &ctx->tk, key ); eiob = alloc_iob ( iob_len ( iob ) + TKIP_HEAD_LEN + TKIP_FOOT_LEN ); if ( ! eiob ) return NULL; /* Copy frame header */ memcpy ( iob_put ( eiob, hdrlen ), iob->data, hdrlen ); hdr = eiob->data; hdr->fc |= IEEE80211_FC_PROTECTED; /* Fill in IV and key ID byte, and extended IV */ memcpy ( &head, key, 3 ); head.kid = 0x20; /* have Extended IV, key ID 0 */ head.tsc_hi = cpu_to_le32 ( ctx->enc.tsc_hi ); memcpy ( iob_put ( eiob, sizeof ( head ) ), &head, sizeof ( head ) ); /* Copy and encrypt the data */ cipher_setkey ( &arc4_algorithm, &arc4, key, 16 ); cipher_encrypt ( &arc4_algorithm, &arc4, iob->data + hdrlen, iob_put ( eiob, datalen ), datalen ); /* Add MIC */ hdr = iob->data; tkip_michael ( &ctx->tk.mic.tx, hdr->addr3, hdr->addr2, iob->data + hdrlen, datalen, mic ); cipher_encrypt ( &arc4_algorithm, &arc4, mic, iob_put ( eiob, sizeof ( mic ) ), sizeof ( mic ) ); /* Add ICV */ icv = crc32_le ( ~0, iob->data + hdrlen, datalen ); icv = crc32_le ( icv, mic, sizeof ( mic ) ); icv = cpu_to_le32 ( ~icv ); cipher_encrypt ( &arc4_algorithm, &arc4, &icv, iob_put ( eiob, TKIP_ICV_LEN ), TKIP_ICV_LEN ); DBGC2 ( ctx, "WPA-TKIP %p: encrypted packet %p -> %p\n", ctx, iob, eiob ); return eiob; } /** * Decrypt a packet using TKIP * * @v crypto TKIP cryptosystem * @v eiob I/O buffer containing encrypted packet * @ret iob I/O buffer containing cleartext packet */ static struct io_buffer * tkip_decrypt ( struct net80211_crypto *crypto, struct io_buffer *eiob ) { struct tkip_ctx *ctx = crypto->priv; struct ieee80211_frame *hdr; struct io_buffer *iob; const int hdrlen = IEEE80211_TYP_FRAME_HEADER_LEN; int datalen = iob_len ( eiob ) - hdrlen - TKIP_HEAD_LEN - TKIP_FOOT_LEN; struct tkip_head *head; struct arc4_ctx arc4; u16 rx_tsc_lo; u8 key[16]; u8 mic[8]; u32 icv, crc; iob = alloc_iob ( hdrlen + datalen + TKIP_FOOT_LEN ); if ( ! iob ) return NULL; /* Copy frame header */ memcpy ( iob_put ( iob, hdrlen ), eiob->data, hdrlen ); hdr = iob->data; hdr->fc &= ~IEEE80211_FC_PROTECTED; /* Check and update TSC */ head = eiob->data + hdrlen; rx_tsc_lo = ( head->tsc1 << 8 ) | head->tsc0; if ( head->tsc_hi < ctx->dec.tsc_hi || ( head->tsc_hi == ctx->dec.tsc_hi && rx_tsc_lo <= ctx->dec.tsc_lo ) ) { DBGC ( ctx, "WPA-TKIP %p: packet received out of order " "(%08x:%04x <= %08x:%04x)\n", ctx, head->tsc_hi, rx_tsc_lo, ctx->dec.tsc_hi, ctx->dec.tsc_lo ); free_iob ( iob ); return NULL; } ctx->dec.tsc_lo = rx_tsc_lo; if ( ctx->dec.tsc_hi != head->tsc_hi ) { ctx->dec.ttak_ok = 0; ctx->dec.tsc_hi = head->tsc_hi; } /* Calculate key */ tkip_mix_1 ( &ctx->dec, &ctx->tk, hdr->addr2 ); tkip_mix_2 ( &ctx->dec, &ctx->tk, key ); /* Copy-decrypt data, MIC, ICV */ cipher_setkey ( &arc4_algorithm, &arc4, key, 16 ); cipher_decrypt ( &arc4_algorithm, &arc4, eiob->data + hdrlen + TKIP_HEAD_LEN, iob_put ( iob, datalen ), datalen + TKIP_FOOT_LEN ); /* Check ICV */ icv = le32_to_cpu ( *( u32 * ) ( iob->tail + TKIP_MIC_LEN ) ); crc = ~crc32_le ( ~0, iob->data + hdrlen, datalen + TKIP_MIC_LEN ); if ( crc != icv ) { DBGC ( ctx, "WPA-TKIP %p CRC mismatch: expect %08x, get %08x\n", ctx, icv, crc ); free_iob ( iob ); return NULL; } /* Check MIC */ tkip_michael ( &ctx->tk.mic.rx, hdr->addr1, hdr->addr3, iob->data + hdrlen, datalen, mic ); if ( memcmp ( mic, iob->tail, TKIP_MIC_LEN ) != 0 ) { DBGC ( ctx, "WPA-TKIP %p ALERT! MIC failure\n", ctx ); /* XXX we should do the countermeasures here */ free_iob ( iob ); return NULL; } DBGC2 ( ctx, "WPA-TKIP %p: decrypted packet %p -> %p\n", ctx, eiob, iob ); return iob; } /** TKIP cryptosystem */ struct net80211_crypto tkip_crypto __net80211_crypto = { .algorithm = NET80211_CRYPT_TKIP, .init = tkip_init, .encrypt = tkip_encrypt, .decrypt = tkip_decrypt, .priv_len = sizeof ( struct tkip_ctx ), }; /** * Calculate HMAC-MD5 MIC for EAPOL-Key frame * * @v kck Key Confirmation Key, 16 bytes * @v msg Message to calculate MIC over * @v len Number of bytes to calculate MIC over * @ret mic Calculated MIC, 16 bytes long */ static void tkip_kie_mic ( const void *kck, const void *msg, size_t len, void *mic ) { uint8_t ctx[MD5_CTX_SIZE]; u8 kckb[16]; size_t kck_len = 16; memcpy ( kckb, kck, kck_len ); hmac_init ( &md5_algorithm, ctx, kckb, &kck_len ); hmac_update ( &md5_algorithm, ctx, msg, len ); hmac_final ( &md5_algorithm, ctx, kckb, &kck_len, mic ); } /** * Decrypt key data in EAPOL-Key frame * * @v kek Key Encryption Key, 16 bytes * @v iv Initialisation vector, 16 bytes * @v msg Message to decrypt * @v len Length of message * @ret msg Decrypted message in place of original * @ret len Unchanged * @ret rc Always 0 for success */ static int tkip_kie_decrypt ( const void *kek, const void *iv, void *msg, u16 *len ) { u8 key[32]; memcpy ( key, iv, 16 ); memcpy ( key + 16, kek, 16 ); arc4_skip ( key, 32, 256, msg, msg, *len ); return 0; } /** TKIP-style key integrity and encryption handler */ struct wpa_kie tkip_kie __wpa_kie = { .version = EAPOL_KEY_VERSION_WPA, .mic = tkip_kie_mic, .decrypt = tkip_kie_decrypt, };