cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ttpci-eeprom.c (3985B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3    Retrieve encoded MAC address from 24C16 serial 2-wire EEPROM,
      4    decode it and store it in the associated adapter struct for
      5    use by dvb_net.c
      6
      7    This card appear to have the 24C16 write protect held to ground,
      8    thus permitting normal read/write operation. Theoretically it
      9    would be possible to write routines to burn a different (encoded)
     10    MAC address into the EEPROM.
     11
     12    Robert Schlabbach	GMX
     13    Michael Glaum	KVH Industries
     14    Holger Waechtler	Convergence
     15
     16    Copyright (C) 2002-2003 Ralph Metzler <rjkm@metzlerbros.de>
     17			    Metzler Brothers Systementwicklung GbR
     18
     19
     20*/
     21
     22#include <asm/errno.h>
     23#include <linux/init.h>
     24#include <linux/module.h>
     25#include <linux/string.h>
     26#include <linux/i2c.h>
     27#include <linux/etherdevice.h>
     28
     29#include "ttpci-eeprom.h"
     30
     31#if 1
     32#define dprintk(x...) do { printk(x); } while (0)
     33#else
     34#define dprintk(x...) do { } while (0)
     35#endif
     36
     37
     38static int check_mac_tt(u8 *buf)
     39{
     40	int i;
     41	u16 tmp = 0xffff;
     42
     43	for (i = 0; i < 8; i++) {
     44		tmp  = (tmp << 8) | ((tmp >> 8) ^ buf[i]);
     45		tmp ^= (tmp >> 4) & 0x0f;
     46		tmp ^= (tmp << 12) ^ ((tmp & 0xff) << 5);
     47	}
     48	tmp ^= 0xffff;
     49	return (((tmp >> 8) ^ buf[8]) | ((tmp & 0xff) ^ buf[9]));
     50}
     51
     52static int getmac_tt(u8 * decodedMAC, u8 * encodedMAC)
     53{
     54	u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
     55		       0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
     56		       0x1d, 0x36, 0x64, 0x78};
     57	u8 data[20];
     58	int i;
     59
     60	/* In case there is a sig check failure have the orig contents available */
     61	memcpy(data, encodedMAC, 20);
     62
     63	for (i = 0; i < 20; i++)
     64		data[i] ^= xor[i];
     65	for (i = 0; i < 10; i++)
     66		data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
     67			>> ((data[2 * i + 1] >> 6) & 3);
     68
     69	if (check_mac_tt(data))
     70		return -ENODEV;
     71
     72	decodedMAC[0] = data[2]; decodedMAC[1] = data[1]; decodedMAC[2] = data[0];
     73	decodedMAC[3] = data[6]; decodedMAC[4] = data[5]; decodedMAC[5] = data[4];
     74	return 0;
     75}
     76
     77int ttpci_eeprom_decode_mac(u8 *decodedMAC, u8 *encodedMAC)
     78{
     79	u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
     80		       0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
     81		       0x1d, 0x36, 0x64, 0x78};
     82	u8 data[20];
     83	int i;
     84
     85	memcpy(data, encodedMAC, 20);
     86
     87	for (i = 0; i < 20; i++)
     88		data[i] ^= xor[i];
     89	for (i = 0; i < 10; i++)
     90		data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
     91			>> ((data[2 * i + 1] >> 6) & 3);
     92
     93	if (check_mac_tt(data))
     94		return -ENODEV;
     95
     96	decodedMAC[0] = data[2];
     97	decodedMAC[1] = data[1];
     98	decodedMAC[2] = data[0];
     99	decodedMAC[3] = data[6];
    100	decodedMAC[4] = data[5];
    101	decodedMAC[5] = data[4];
    102	return 0;
    103}
    104EXPORT_SYMBOL(ttpci_eeprom_decode_mac);
    105
    106static int ttpci_eeprom_read_encodedMAC(struct i2c_adapter *adapter, u8 * encodedMAC)
    107{
    108	int ret;
    109	u8 b0[] = { 0xcc };
    110
    111	struct i2c_msg msg[] = {
    112		{ .addr = 0x50, .flags = 0, .buf = b0, .len = 1 },
    113		{ .addr = 0x50, .flags = I2C_M_RD, .buf = encodedMAC, .len = 20 }
    114	};
    115
    116	/* dprintk("%s\n", __func__); */
    117
    118	ret = i2c_transfer(adapter, msg, 2);
    119
    120	if (ret != 2)		/* Assume EEPROM isn't there */
    121		return (-ENODEV);
    122
    123	return 0;
    124}
    125
    126
    127int ttpci_eeprom_parse_mac(struct i2c_adapter *adapter, u8 *proposed_mac)
    128{
    129	int ret;
    130	u8 encodedMAC[20];
    131	u8 decodedMAC[6];
    132
    133	ret = ttpci_eeprom_read_encodedMAC(adapter, encodedMAC);
    134
    135	if (ret != 0) {		/* Will only be -ENODEV */
    136		dprintk("Couldn't read from EEPROM: not there?\n");
    137		eth_zero_addr(proposed_mac);
    138		return ret;
    139	}
    140
    141	ret = getmac_tt(decodedMAC, encodedMAC);
    142	if( ret != 0 ) {
    143		dprintk("adapter failed MAC signature check\n");
    144		dprintk("encoded MAC from EEPROM was %*phC",
    145			(int)sizeof(encodedMAC), &encodedMAC);
    146		eth_zero_addr(proposed_mac);
    147		return ret;
    148	}
    149
    150	memcpy(proposed_mac, decodedMAC, 6);
    151	dprintk("adapter has MAC addr = %pM\n", decodedMAC);
    152	return 0;
    153}
    154
    155EXPORT_SYMBOL(ttpci_eeprom_parse_mac);
    156
    157MODULE_LICENSE("GPL");
    158MODULE_AUTHOR("Ralph Metzler, Marcus Metzler, others");
    159MODULE_DESCRIPTION("Decode dvb_net MAC address from EEPROM of PCI DVB cards made by Siemens, Technotrend, Hauppauge");