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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2018 Facebook Inc
* Copyright (C) 2015-2016 Intel Corp.
* (Written by Andrey Petrov <andrey.petrov@intel.com> for Intel Corp.)
* (Written by Alexandru Gagniuc <alexandrux.gagniuc@intel.com> for Intel Corp.)
*
* 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; version 2 of the License.
*
* 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.
*/
#include <security/vboot/antirollback.h>
#include <program_loading.h>
#include <security/vboot/vboot_common.h>
#include <vb2_api.h>
#include <security/tpm/tss.h>
#include <fsp/memory_init.h>
#include <console/console.h>
#include <string.h>
void mrc_cache_update_hash(const uint8_t *data, size_t size)
{
uint8_t data_hash[VB2_SHA256_DIGEST_SIZE];
static const uint8_t dead_hash[VB2_SHA256_DIGEST_SIZE] = {
0xba, 0xad, 0xda, 0x1a, /* BAADDA1A */
0xde, 0xad, 0xde, 0xad, /* DEADDEAD */
0xde, 0xad, 0xda, 0x1a, /* DEADDA1A */
0xba, 0xad, 0xba, 0xad, /* BAADBAAD */
0xba, 0xad, 0xda, 0x1a, /* BAADDA1A */
0xde, 0xad, 0xde, 0xad, /* DEADDEAD */
0xde, 0xad, 0xda, 0x1a, /* DEADDA1A */
0xba, 0xad, 0xba, 0xad, /* BAADBAAD */
};
const uint8_t *hash_ptr = data_hash;
/* We do not store normal mode data hash in TPM. */
if (!vboot_recovery_mode_enabled())
return;
/* Initialize TPM driver. */
if (tlcl_lib_init() != VB2_SUCCESS) {
printk(BIOS_ERR, "MRC: TPM driver initialization failed.\n");
return;
}
/* Calculate hash of data generated by MRC. */
if (vb2_digest_buffer(data, size, VB2_HASH_SHA256, data_hash,
sizeof(data_hash))) {
printk(BIOS_ERR, "MRC: SHA-256 calculation failed for data. "
"Not updating TPM hash space.\n");
/*
* Since data is being updated in recovery cache, the hash
* currently stored in TPM recovery hash space is no longer
* valid. If we are not able to calculate hash of the data being
* updated, reset all the bits in TPM recovery hash space to
* pre-defined hash pattern.
*/
hash_ptr = dead_hash;
}
/* Write hash of data to TPM space. */
if (antirollback_write_space_rec_hash(hash_ptr, VB2_SHA256_DIGEST_SIZE)
!= TPM_SUCCESS) {
printk(BIOS_ERR, "MRC: Could not save hash to TPM.\n");
return;
}
printk(BIOS_INFO, "MRC: TPM MRC hash updated successfully.\n");
}
int mrc_cache_verify_hash(const uint8_t *data, size_t size)
{
uint8_t data_hash[VB2_SHA256_DIGEST_SIZE];
uint8_t tpm_hash[VB2_SHA256_DIGEST_SIZE];
/* We do not store normal mode data hash in TPM. */
if (!vboot_recovery_mode_enabled())
return 1;
/* Calculate hash of data read from RECOVERY_MRC_CACHE. */
if (vb2_digest_buffer(data, size, VB2_HASH_SHA256, data_hash,
sizeof(data_hash))) {
printk(BIOS_ERR, "MRC: SHA-256 calculation failed for data.\n");
return 0;
}
/* Initialize TPM driver. */
if (tlcl_lib_init() != VB2_SUCCESS) {
printk(BIOS_ERR, "MRC: TPM driver initialization failed.\n");
return 0;
}
/* Read hash of MRC data saved in TPM. */
if (antirollback_read_space_rec_hash(tpm_hash, sizeof(tpm_hash))
!= TPM_SUCCESS) {
printk(BIOS_ERR, "MRC: Could not read hash from TPM.\n");
return 0;
}
if (memcmp(tpm_hash, data_hash, sizeof(tpm_hash))) {
printk(BIOS_ERR, "MRC: Hash comparison failed.\n");
return 0;
}
printk(BIOS_INFO, "MRC: Hash comparison successful. "
"Using data from RECOVERY_MRC_CACHE\n");
return 1;
}
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