mirror of https://github.com/ipxe/ipxe.git
[wpa] Add TKIP backend (legacy RC4-based cryptosystem)
Signed-off-by: Marty Connor <mdc@etherboot.org>pull/1/head
Joshua Oreman
Marty Connor
parent
0758111345
commit
8106cb130b
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@ -38,3 +38,8 @@ REQUIRE_OBJECT ( wireless_errors );
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#ifdef CRYPTO_80211_WEP
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REQUIRE_OBJECT ( wep );
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#endif
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#ifdef CRYPTO_80211_WPA
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REQUIRE_OBJECT ( wpa_psk );
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REQUIRE_OBJECT ( wpa_tkip );
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#endif
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@ -69,7 +69,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
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*
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*/
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#define CRYPTO_80211_WEP /* WEP encryption (deprecated and insecure!) */
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#define CRYPTO_80211_WPA_PSK /* WPA "Personal" frontend using a passphrase */
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#define CRYPTO_80211_WPA /* WPA Personal, authenticating with passphrase */
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/*
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* Name resolution modules
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@ -163,6 +163,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
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#define ERRFILE_eapol ( ERRFILE_NET | 0x00250000 )
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#define ERRFILE_wpa ( ERRFILE_NET | 0x00260000 )
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#define ERRFILE_wpa_psk ( ERRFILE_NET | 0x00270000 )
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#define ERRFILE_wpa_tkip ( ERRFILE_NET | 0x00280000 )
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#define ERRFILE_image ( ERRFILE_IMAGE | 0x00000000 )
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#define ERRFILE_elf ( ERRFILE_IMAGE | 0x00010000 )
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@ -0,0 +1,586 @@
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/*
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* Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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FILE_LICENCE ( GPL2_OR_LATER );
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#include <gpxe/net80211.h>
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#include <gpxe/crypto.h>
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#include <gpxe/hmac.h>
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#include <gpxe/sha1.h>
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#include <gpxe/md5.h>
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#include <gpxe/crc32.h>
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#include <gpxe/arc4.h>
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#include <gpxe/wpa.h>
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#include <byteswap.h>
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#include <errno.h>
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/** @file
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*
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* Backend for WPA using the TKIP encryption standard.
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*/
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/** Context for one direction of TKIP, either encryption or decryption */
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struct tkip_dir_ctx
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{
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/** High 32 bits of last sequence counter value used */
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u32 tsc_hi;
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/** Low 32 bits of last sequence counter value used */
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u16 tsc_lo;
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/** MAC address used to derive TTAK */
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u8 mac[ETH_ALEN];
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/** If TRUE, TTAK is valid */
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u16 ttak_ok;
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/** TKIP-mixed transmit address and key, depends on tsc_hi and MAC */
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u16 ttak[5];
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};
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/** Context for TKIP encryption and decryption */
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struct tkip_ctx
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{
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/** Temporal key to use */
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struct tkip_tk tk;
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/** State for encryption */
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struct tkip_dir_ctx enc;
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/** State for decryption */
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struct tkip_dir_ctx dec;
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};
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/** Header structure at the beginning of TKIP frame data */
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struct tkip_head
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{
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u8 tsc1; /**< High byte of low 16 bits of TSC */
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u8 seed1; /**< Second byte of WEP seed */
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u8 tsc0; /**< Low byte of TSC */
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u8 kid; /**< Key ID and ExtIV byte */
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u32 tsc_hi; /**< High 32 bits of TSC, as an ExtIV */
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} __attribute__ (( packed ));
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/** TKIP header overhead (IV + KID + ExtIV) */
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#define TKIP_HEAD_LEN 8
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/** TKIP trailer overhead (MIC + ICV) [assumes unfragmented] */
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#define TKIP_FOOT_LEN 12
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/** TKIP MIC length */
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#define TKIP_MIC_LEN 8
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/** TKIP ICV length */
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#define TKIP_ICV_LEN 4
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/** TKIP S-box */
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static const u16 Sbox[256] = {
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0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154,
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0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A,
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0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B,
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0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B,
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0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F,
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0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F,
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0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5,
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0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F,
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0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB,
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0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397,
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0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED,
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0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A,
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0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194,
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0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3,
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0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104,
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0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D,
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0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39,
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0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695,
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0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83,
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0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76,
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0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4,
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0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B,
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0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0,
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0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018,
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0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751,
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0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85,
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0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12,
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0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9,
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0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7,
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0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A,
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0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8,
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0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A,
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};
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/**
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* Perform S-box mapping on a 16-bit value
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*
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* @v v Value to perform S-box mapping on
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* @ret Sv S-box mapped value
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*/
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static inline u16 S ( u16 v )
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{
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return Sbox[v & 0xFF] ^ swap16 ( Sbox[v >> 8] );
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}
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/**
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* Rotate 16-bit value right
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*
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* @v v Value to rotate
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* @v bits Number of bits to rotate by
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* @ret rotv Rotated value
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*/
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static inline u16 ror16 ( u16 v, int bits )
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{
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return ( v >> bits ) | ( v << ( 16 - bits ) );
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}
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/**
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* Rotate 32-bit value right
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*
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* @v v Value to rotate
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* @v bits Number of bits to rotate by
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* @ret rotv Rotated value
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*/
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static inline u32 ror32 ( u32 v, int bits )
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{
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return ( v >> bits ) | ( v << ( 32 - bits ) );
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}
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/**
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* Rotate 32-bit value left
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*
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* @v v Value to rotate
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* @v bits Number of bits to rotate by
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* @ret rotv Rotated value
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*/
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static inline u32 rol32 ( u32 v, int bits )
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{
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return ( v << bits ) | ( v >> ( 32 - bits ) );
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}
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/**
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* Initialise TKIP state and install key
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*
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* @v crypto TKIP cryptosystem structure
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* @v key Pointer to tkip_tk to install
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* @v keylen Length of key (32 bytes)
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* @v rsc Initial receive sequence counter
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*/
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static int tkip_init ( struct net80211_crypto *crypto, const void *key,
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int keylen, const void *rsc )
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{
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struct tkip_ctx *ctx = crypto->priv;
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const u8 *rscb = rsc;
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if ( keylen != sizeof ( ctx->tk ) )
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return -EINVAL;
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if ( rscb ) {
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ctx->dec.tsc_lo = ( rscb[1] << 8 ) | rscb[0];
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ctx->dec.tsc_hi = ( ( rscb[5] << 24 ) | ( rscb[4] << 16 ) |
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( rscb[3] << 8 ) | rscb[2] );
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}
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memcpy ( &ctx->tk, key, sizeof ( ctx->tk ) );
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return 0;
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}
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/**
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* Perform TKIP key mixing, phase 1
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*
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* @v dctx TKIP directional context
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* @v tk TKIP temporal key
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* @v mac MAC address of transmitter
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*
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* This recomputes the TTAK in @a dctx if necessary, and sets
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* @c dctx->ttak_ok.
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*/
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static void tkip_mix_1 ( struct tkip_dir_ctx *dctx, struct tkip_tk *tk, u8 *mac )
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{
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int i, j;
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if ( dctx->ttak_ok && ! memcmp ( mac, dctx->mac, ETH_ALEN ) )
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return;
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memcpy ( dctx->mac, mac, ETH_ALEN );
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dctx->ttak[0] = dctx->tsc_hi & 0xFFFF;
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dctx->ttak[1] = dctx->tsc_hi >> 16;
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dctx->ttak[2] = ( mac[1] << 8 ) | mac[0];
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dctx->ttak[3] = ( mac[3] << 8 ) | mac[2];
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dctx->ttak[4] = ( mac[5] << 8 ) | mac[4];
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for ( i = 0; i < 8; i++ ) {
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j = 2 * ( i & 1 );
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dctx->ttak[0] += S ( dctx->ttak[4] ^ ( ( tk->key[1 + j] << 8 ) |
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tk->key[0 + j] ) );
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dctx->ttak[1] += S ( dctx->ttak[0] ^ ( ( tk->key[5 + j] << 8 ) |
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tk->key[4 + j] ) );
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dctx->ttak[2] += S ( dctx->ttak[1] ^ ( ( tk->key[9 + j] << 8 ) |
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tk->key[8 + j] ) );
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dctx->ttak[3] += S ( dctx->ttak[2] ^ ( ( tk->key[13+ j] << 8 ) |
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tk->key[12+ j] ) );
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dctx->ttak[4] += S ( dctx->ttak[3] ^ ( ( tk->key[1 + j] << 8 ) |
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tk->key[0 + j] ) ) + i;
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}
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dctx->ttak_ok = 1;
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}
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/**
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* Perform TKIP key mixing, phase 2
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*
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* @v dctx TKIP directional context
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* @v tk TKIP temporal key
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* @ret key ARC4 key, 16 bytes long
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*/
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static void tkip_mix_2 ( struct tkip_dir_ctx *dctx, struct tkip_tk *tk,
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void *key )
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{
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u8 *kb = key;
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u16 ppk[6];
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int i;
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memcpy ( ppk, dctx->ttak, sizeof ( dctx->ttak ) );
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ppk[5] = dctx->ttak[4] + dctx->tsc_lo;
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ppk[0] += S ( ppk[5] ^ ( ( tk->key[1] << 8 ) | tk->key[0] ) );
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ppk[1] += S ( ppk[0] ^ ( ( tk->key[3] << 8 ) | tk->key[2] ) );
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ppk[2] += S ( ppk[1] ^ ( ( tk->key[5] << 8 ) | tk->key[4] ) );
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ppk[3] += S ( ppk[2] ^ ( ( tk->key[7] << 8 ) | tk->key[6] ) );
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ppk[4] += S ( ppk[3] ^ ( ( tk->key[9] << 8 ) | tk->key[8] ) );
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ppk[5] += S ( ppk[4] ^ ( ( tk->key[11] << 8 ) | tk->key[10] ) );
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ppk[0] += ror16 ( ppk[5] ^ ( ( tk->key[13] << 8 ) | tk->key[12] ), 1 );
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ppk[1] += ror16 ( ppk[0] ^ ( ( tk->key[15] << 8 ) | tk->key[14] ), 1 );
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ppk[2] += ror16 ( ppk[1], 1 );
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ppk[3] += ror16 ( ppk[2], 1 );
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ppk[4] += ror16 ( ppk[3], 1 );
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ppk[5] += ror16 ( ppk[4], 1 );
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kb[0] = dctx->tsc_lo >> 8;
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kb[1] = ( ( dctx->tsc_lo >> 8 ) | 0x20 ) & 0x7F;
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kb[2] = dctx->tsc_lo & 0xFF;
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kb[3] = ( ( ppk[5] ^ ( ( tk->key[1] << 8 ) | tk->key[0] ) ) >> 1 )
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& 0xFF;
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for ( i = 0; i < 6; i++ ) {
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kb[4 + 2*i] = ppk[i] & 0xFF;
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kb[5 + 2*i] = ppk[i] >> 8;
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}
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}
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/**
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* Update Michael message integrity code based on next 32-bit word of data
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*
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* @v V Michael code state (two 32-bit words)
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* @v word Next 32-bit word of data
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*/
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static void tkip_feed_michael ( u32 *V, u32 word )
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{
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V[0] ^= word;
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V[1] ^= rol32 ( V[0], 17 );
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V[0] += V[1];
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V[1] ^= ( ( V[0] & 0xFF00FF00 ) >> 8 ) | ( ( V[0] & 0x00FF00FF ) << 8 );
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V[0] += V[1];
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V[1] ^= rol32 ( V[0], 3 );
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V[0] += V[1];
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V[1] ^= ror32 ( V[0], 2 );
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V[0] += V[1];
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}
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/**
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* Calculate Michael message integrity code
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*
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* @v key MIC key to use (8 bytes)
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* @v da Destination link-layer address
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* @v sa Source link-layer address
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* @v data Start of data to calculate over
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* @v len Length of header + data
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* @ret mic Calculated Michael MIC (8 bytes)
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*/
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static void tkip_michael ( const void *key, const void *da, const void *sa,
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const void *data, size_t len, void *mic )
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{
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u32 V[2]; /* V[0] = "l", V[1] = "r" in 802.11 */
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union {
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u8 byte[12];
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u32 word[3];
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} cap;
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const u8 *ptr = data;
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const u8 *end = ptr + len;
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int i;
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memcpy ( V, key, sizeof ( V ) );
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V[0] = le32_to_cpu ( V[0] );
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V[1] = le32_to_cpu ( V[1] );
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/* Feed in header (we assume non-QoS, so Priority = 0) */
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memcpy ( &cap.byte[0], da, ETH_ALEN );
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memcpy ( &cap.byte[6], sa, ETH_ALEN );
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tkip_feed_michael ( V, le32_to_cpu ( cap.word[0] ) );
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tkip_feed_michael ( V, le32_to_cpu ( cap.word[1] ) );
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tkip_feed_michael ( V, le32_to_cpu ( cap.word[2] ) );
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tkip_feed_michael ( V, 0 );
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/* Feed in data */
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while ( ptr + 4 <= end ) {
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tkip_feed_michael ( V, le32_to_cpu ( *( u32 * ) ptr ) );
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ptr += 4;
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}
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/* Add unaligned part and padding */
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for ( i = 0; ptr < end; i++ )
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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 )
|
||||
{
|
||||
struct md5_ctx md5;
|
||||
u8 kckb[16];
|
||||
size_t kck_len = 16;
|
||||
|
||||
memcpy ( kckb, kck, kck_len );
|
||||
|
||||
hmac_init ( &md5_algorithm, &md5, kckb, &kck_len );
|
||||
hmac_update ( &md5_algorithm, &md5, msg, len );
|
||||
hmac_final ( &md5_algorithm, &md5, 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,
|
||||
};
|
||||
Loading…
Reference in New Issue