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/* SPDX-License-Identifier: GPL-2.0-only */
#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 <security/vboot/mrc_cache_hash_tpm.h>
#include <console/console.h>
#include <string.h>
void mrc_cache_update_hash(uint32_t index, 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;
/* 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 mrc cache, the hash
* currently stored in TPM 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 hash
* space to pre-defined hash pattern.
*/
hash_ptr = dead_hash;
}
/* Write hash of data to TPM space. */
if (antirollback_write_space_mrc_hash(index, 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 idx 0x%x updated successfully.\n", index);
}
int mrc_cache_verify_hash(uint32_t index, const uint8_t *data, size_t size)
{
uint8_t data_hash[VB2_SHA256_DIGEST_SIZE];
uint8_t tpm_hash[VB2_SHA256_DIGEST_SIZE];
/* Calculate hash of data read from 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_mrc_hash(index, 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 idx 0x%x comparison successful.\n", index);
return 1;
}
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