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/* SPDX-License-Identifier: GPL-2.0-only */
#include <security/vboot/antirollback.h>
#include <program_loading.h>
#include <vb2_api.h>
#include <security/tpm/tss.h>
#include <security/vboot/misc.h>
#include <security/vboot/vbios_cache_hash_tpm.h>
#include <console/console.h>
#include <string.h>
void vbios_cache_update_hash(const uint8_t *data, size_t size)
{
struct vb2_hash hash;
tpm_result_t rc = TPM_SUCCESS;
/* Initialize TPM driver. */
rc = tlcl_lib_init();
if (rc != TPM_SUCCESS) {
printk(BIOS_ERR, "VBIOS_CACHE: TPM driver initialization failed with error %#x.\n", rc);
return;
}
/* Calculate hash of vbios data. */
if (vb2_hash_calculate(vboot_hwcrypto_allowed(), data, size,
VB2_HASH_SHA256, &hash)) {
printk(BIOS_ERR, "VBIOS_CACHE: SHA-256 calculation failed for data; "
"clearing TPM hash space.\n");
/*
* Since data is being updated in vbios 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 zero to invalidate it.
*/
memset(hash.raw, 0, VB2_SHA256_DIGEST_SIZE);
}
/* Write hash of data to TPM space. */
rc = antirollback_write_space_vbios_hash(hash.sha256, sizeof(hash.sha256));
if (rc != TPM_SUCCESS) {
printk(BIOS_ERR, "VBIOS_CACHE: Could not save hash to TPM with error %#x.\n", rc);
return;
}
printk(BIOS_INFO, "VBIOS_CACHE: TPM NV idx %#x updated successfully.\n",
VBIOS_CACHE_NV_INDEX);
}
enum cb_err vbios_cache_verify_hash(const uint8_t *data, size_t size)
{
struct vb2_hash tpm_hash = { .algo = VB2_HASH_SHA256 };
tpm_result_t rc = TPM_SUCCESS;
/* Initialize TPM driver. */
rc = tlcl_lib_init();
if (rc != TPM_SUCCESS) {
printk(BIOS_ERR, "VBIOS_CACHE: TPM driver initialization failed with error %#x.\n", rc);
return CB_ERR;
}
/* Read hash of VBIOS data saved in TPM. */
rc = antirollback_read_space_vbios_hash(tpm_hash.sha256, sizeof(tpm_hash.sha256));
if (rc != TPM_SUCCESS) {
printk(BIOS_ERR, "VBIOS_CACHE: Could not read hash from TPM with error %#x.\n", rc);
return CB_ERR;
}
/* Calculate hash of data read from VBIOS FMAP CACHE and compare. */
if (vb2_hash_verify(vboot_hwcrypto_allowed(), data, size, &tpm_hash)) {
printk(BIOS_ERR, "VBIOS_CACHE: Hash comparison failed.\n");
return CB_ERR;
}
printk(BIOS_INFO, "VBIOS_CACHE: Hash idx %#x comparison successful.\n",
VBIOS_CACHE_NV_INDEX);
return CB_SUCCESS;
}
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