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/*
* This file is part of the coreboot project.
*
* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
* Copyright 2017 Facebook Inc.
*
* 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 <console/cbmem_console.h>
#include <console/console.h>
#include <reset.h>
#include <security/tpm/tspi.h>
#include <security/tpm/tss.h>
#include <stdlib.h>
#include <string.h>
#if IS_ENABLED(CONFIG_TPM1)
static uint32_t tpm1_invoke_state_machine(void)
{
uint8_t disable;
uint8_t deactivated;
uint32_t result = TPM_SUCCESS;
/* Check that the TPM is enabled and activated. */
result = tlcl_get_flags(&disable, &deactivated, NULL);
if (result != TPM_SUCCESS) {
printk(BIOS_ERR, "TPM: Can't read capabilities.\n");
return result;
}
if (!!deactivated != IS_ENABLED(CONFIG_TPM_DEACTIVATE)) {
printk(BIOS_INFO,
"TPM: Unexpected TPM deactivated state. Toggling...\n");
result = tlcl_set_deactivated(!deactivated);
if (result != TPM_SUCCESS) {
printk(BIOS_ERR,
"TPM: Can't toggle deactivated state.\n");
return result;
}
deactivated = !deactivated;
result = TPM_E_MUST_REBOOT;
}
if (disable && !deactivated) {
printk(BIOS_INFO, "TPM: disabled (%d). Enabling...\n", disable);
result = tlcl_set_enable();
if (result != TPM_SUCCESS) {
printk(BIOS_ERR, "TPM: Can't set enabled state.\n");
return result;
}
printk(BIOS_INFO, "TPM: Must reboot to re-enable\n");
result = TPM_E_MUST_REBOOT;
}
return result;
}
#endif
/*
* tpm_setup starts the TPM and establishes the root of trust for the
* anti-rollback mechanism. SetupTPM can fail for three reasons. 1 A bug. 2 a
* TPM hardware failure. 3 An unexpected TPM state due to some attack. In
* general we cannot easily distinguish the kind of failure, so our strategy is
* to reboot in recovery mode in all cases. The recovery mode calls SetupTPM
* again, which executes (almost) the same sequence of operations. There is a
* good chance that, if recovery mode was entered because of a TPM failure, the
* failure will repeat itself. (In general this is impossible to guarantee
* because we have no way of creating the exact TPM initial state at the
* previous boot.) In recovery mode, we ignore the failure and continue, thus
* giving the recovery kernel a chance to fix things (that's why we don't set
* bGlobalLock). The choice is between a knowingly insecure device and a
* bricked device.
*
* As a side note, observe that we go through considerable hoops to avoid using
* the STCLEAR permissions for the index spaces. We do this to avoid writing
* to the TPM flashram at every reboot or wake-up, because of concerns about
* the durability of the NVRAM.
*/
uint32_t tpm_setup(int s3flag)
{
uint32_t result;
result = tlcl_lib_init();
if (result != TPM_SUCCESS) {
printk(BIOS_ERR, "TPM: Can't initialize.\n");
goto out;
}
/* Handle special init for S3 resume path */
if (s3flag) {
result = tlcl_resume();
if (result == TPM_E_INVALID_POSTINIT)
printk(BIOS_INFO, "TPM: Already initialized.\n");
return TPM_SUCCESS;
}
result = tlcl_startup();
if (result != TPM_SUCCESS) {
printk(BIOS_ERR, "TPM: Can't run startup command.\n");
goto out;
}
result = tlcl_assert_physical_presence();
if (result != TPM_SUCCESS) {
/*
* It is possible that the TPM was delivered with the physical
* presence command disabled. This tries enabling it, then
* tries asserting PP again.
*/
result = tlcl_physical_presence_cmd_enable();
if (result != TPM_SUCCESS) {
printk(
BIOS_ERR,
"TPM: Can't enable physical presence command.\n");
goto out;
}
result = tlcl_assert_physical_presence();
if (result != TPM_SUCCESS) {
printk(BIOS_ERR,
"TPM: Can't assert physical presence.\n");
goto out;
}
}
#if IS_ENABLED(CONFIG_TPM1)
result = tpm1_invoke_state_machine();
if (result != TPM_SUCCESS)
return result;
#endif
out:
if (result != TPM_SUCCESS)
post_code(POST_TPM_FAILURE);
else
printk(BIOS_INFO, "TPM: setup succeeded\n");
return result;
}
uint32_t tpm_clear_and_reenable(void)
{
uint32_t result;
printk(BIOS_INFO, "TPM: Clear and re-enable\n");
result = tlcl_force_clear();
if (result != TPM_SUCCESS) {
printk(BIOS_ERR, "TPM: Can't initiate a force clear.\n");
return result;
}
#if IS_ENABLED(CONFIG_TPM1)
result = tlcl_set_enable();
if (result != TPM_SUCCESS) {
printk(BIOS_ERR, "TPM: Can't set enabled state.\n");
return result;
}
result = tlcl_set_deactivated(0);
if (result != TPM_SUCCESS) {
printk(BIOS_ERR, "TPM: Can't set deactivated state.\n");
return result;
}
#endif
return TPM_SUCCESS;
}
uint32_t tpm_extend_pcr(int pcr, uint8_t *digest,
size_t digest_len, const char *name)
{
uint32_t result;
if (!digest)
return TPM_E_IOERROR;
result = tlcl_extend(pcr, digest, NULL);
if (result != TPM_SUCCESS)
return result;
tcpa_log_add_table_entry(name, pcr, digest, digest_len);
return TPM_SUCCESS;
}
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