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			75 lines
		
	
	
		
			1.6 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			75 lines
		
	
	
		
			1.6 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/* intelmetool
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 *
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 * Copyright (C) 2013-2016 Philipp Deppenwiese <zaolin@das-labor.org>,
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 * Copyright (C) 2013-2016 Alexander Couzens <lynxis@fe80.eu>
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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
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 * the 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,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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 * GNU General Public License for more details.
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 */
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include "msr.h"
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#ifndef __DARWIN__
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static int fd_msr = 0;
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static int rdmsr(int addr, uint64_t *msr)
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{
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	if (lseek(fd_msr, (off_t) addr, SEEK_SET) == -1) {
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		perror("Could not lseek() to MSR");
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		close(fd_msr);
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		return -1;
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	}
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	if (read(fd_msr, msr, 8) == 8) {
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		close(fd_msr);
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		return 0;
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	}
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	if (errno == EIO) {
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		perror("IO error couldn't read MSR.");
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		close(fd_msr);
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		/* On older platforms the MSR might not exists */
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		return -2;
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	}
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	perror("Couldn't read() MSR");
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	close(fd_msr);
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	return -1;
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}
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#endif
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int msr_bootguard(uint64_t *msr, int debug)
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{
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#ifndef __DARWIN__
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	fd_msr = open("/dev/cpu/0/msr", O_RDONLY);
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	if (fd_msr < 0) {
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		perror("Error while opening /dev/cpu/0/msr");
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		printf("Did you run 'modprobe msr'?\n");
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		return -1;
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	}
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	if (rdmsr(MSR_BOOTGUARD, msr) < 0)
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		return -1;
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#endif
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	if (!debug)
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		*msr &= ~0xff;
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	return 0;
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}
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