| /* |
| * Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>. |
| * |
| * 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 <string.h> |
| #include <ipxe/net80211.h> |
| #include <ipxe/crypto.h> |
| #include <ipxe/hmac.h> |
| #include <ipxe/sha1.h> |
| #include <ipxe/md5.h> |
| #include <ipxe/crc32.h> |
| #include <ipxe/arc4.h> |
| #include <ipxe/wpa.h> |
| #include <byteswap.h> |
| #include <errno.h> |
| |
| /** @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, |
| }; |