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 (at your option) 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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