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/*
* Copyright (c) 2022 Arm Limited. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*
* DRTM measurements into TPM PCRs.
*
* Authors:
* Lucian Paul-Trifu <lucian.paultrifu@gmail.com>
*
*/
#include <assert.h>
#include <common/debug.h>
#include <drivers/auth/crypto_mod.h>
#include <drivers/measured_boot/event_log/event_log.h>
#include "drtm_main.h"
#include "drtm_measurements.h"
#include <lib/xlat_tables/xlat_tables_v2.h>
/* Event Log buffer */
static uint8_t drtm_event_log[PLAT_DRTM_EVENT_LOG_MAX_SIZE];
/*
* Calculate and write hash of various payloads as per DRTM specification
* to Event Log.
*
* @param[in] data_base Address of data
* @param[in] data_size Size of data
* @param[in] event_type Type of Event
* @param[in] event_name Name of the Event
* @return:
* 0 = success
* < 0 = error
*/
static int drtm_event_log_measure_and_record(uintptr_t data_base,
uint32_t data_size,
uint32_t event_type,
const char *event_name,
unsigned int pcr)
{
int rc;
unsigned char hash_data[CRYPTO_MD_MAX_SIZE];
event_log_metadata_t metadata = {0};
metadata.name = event_name;
metadata.pcr = pcr;
/*
* Measure the payloads requested by D-CRTM and DCE commponents
* Hash algorithm decided by the Event Log driver at build-time
*/
rc = event_log_measure(data_base, data_size, hash_data);
if (rc != 0) {
return rc;
}
/* Record the mesasurement in the EventLog buffer */
event_log_record(hash_data, event_type, &metadata);
return 0;
}
/*
* Initialise Event Log global variables, used during the recording
* of various payload measurements into the Event Log buffer
*
* @param[in] event_log_start Base address of Event Log buffer
* @param[in] event_log_finish End address of Event Log buffer,
* it is a first byte past end of the
* buffer
*/
static void drtm_event_log_init(uint8_t *event_log_start,
uint8_t *event_log_finish)
{
event_log_buf_init(event_log_start, event_log_finish);
event_log_write_specid_event();
}
enum drtm_retc drtm_take_measurements(const struct_drtm_dl_args *a)
{
int rc;
uintptr_t dlme_img_mapping;
uint64_t dlme_img_ep;
size_t dlme_img_mapping_bytes;
uint8_t drtm_null_data = 0U;
uint8_t pcr_schema = DL_ARGS_GET_PCR_SCHEMA(a);
const char *drtm_event_arm_sep_data = "ARM_DRTM";
/* Initialise the EventLog driver */
drtm_event_log_init(drtm_event_log, drtm_event_log +
sizeof(drtm_event_log));
/**
* Measurements extended into PCR-17.
*
* PCR-17: Measure the DCE image. Extend digest of (char)0 into PCR-17
* since the D-CRTM and the DCE are not separate.
*/
rc = drtm_event_log_measure_and_record((uintptr_t)&drtm_null_data,
sizeof(drtm_null_data),
DRTM_EVENT_ARM_DCE, NULL,
PCR_17);
CHECK_RC(rc, drtm_event_log_measure_and_record(DRTM_EVENT_ARM_DCE));
/* PCR-17: Measure the PCR schema DRTM launch argument. */
rc = drtm_event_log_measure_and_record((uintptr_t)&pcr_schema,
sizeof(pcr_schema),
DRTM_EVENT_ARM_PCR_SCHEMA,
NULL, PCR_17);
CHECK_RC(rc,
drtm_event_log_measure_and_record(DRTM_EVENT_ARM_PCR_SCHEMA));
/* PCR-17: Measure the enable state of external-debug, and trace. */
/*
* TODO: Measure the enable state of external-debug and trace. This should
* be returned through a platform-specific hook.
*/
/* PCR-17: Measure the security lifecycle state. */
/*
* TODO: Measure the security lifecycle state. This is an implementation-
* defined value, retrieved through an implementation-defined mechanisms.
*/
/*
* PCR-17: Optionally measure the NWd DCE.
* It is expected that such subsequent DCE stages are signed and verified.
* Whether they are measured in addition to signing is implementation
* -defined.
* Here the choice is to not measure any NWd DCE, in favour of PCR value
* resilience to any NWd DCE updates.
*/
/* PCR-17: End of DCE measurements. */
rc = drtm_event_log_measure_and_record((uintptr_t)drtm_event_arm_sep_data,
strlen(drtm_event_arm_sep_data),
DRTM_EVENT_ARM_SEPARATOR, NULL,
PCR_17);
CHECK_RC(rc, drtm_event_log_measure_and_record(DRTM_EVENT_ARM_SEPARATOR));
/**
* Measurements extended into PCR-18.
*
* PCR-18: Measure the PCR schema DRTM launch argument.
*/
rc = drtm_event_log_measure_and_record((uintptr_t)&pcr_schema,
sizeof(pcr_schema),
DRTM_EVENT_ARM_PCR_SCHEMA,
NULL, PCR_18);
CHECK_RC(rc,
drtm_event_log_measure_and_record(DRTM_EVENT_ARM_PCR_SCHEMA));
/*
* PCR-18: Measure the public key used to verify DCE image(s) signatures.
* Extend digest of (char)0, since we do not expect the NWd DCE to be
* present.
*/
assert(a->dce_nwd_size == 0);
rc = drtm_event_log_measure_and_record((uintptr_t)&drtm_null_data,
sizeof(drtm_null_data),
DRTM_EVENT_ARM_DCE_PUBKEY,
NULL, PCR_18);
CHECK_RC(rc,
drtm_event_log_measure_and_record(DRTM_EVENT_ARM_DCE_PUBKEY));
/* PCR-18: Measure the DLME image. */
dlme_img_mapping_bytes = page_align(a->dlme_img_size, UP);
rc = mmap_add_dynamic_region_alloc_va(a->dlme_paddr + a->dlme_img_off,
&dlme_img_mapping,
dlme_img_mapping_bytes, MT_RO_DATA | MT_NS);
if (rc) {
WARN("DRTM: %s: mmap_add_dynamic_region() failed rc=%d\n",
__func__, rc);
return INTERNAL_ERROR;
}
rc = drtm_event_log_measure_and_record(dlme_img_mapping, a->dlme_img_size,
DRTM_EVENT_ARM_DLME, NULL,
PCR_18);
CHECK_RC(rc, drtm_event_log_measure_and_record(DRTM_EVENT_ARM_DLME));
rc = mmap_remove_dynamic_region(dlme_img_mapping, dlme_img_mapping_bytes);
CHECK_RC(rc, mmap_remove_dynamic_region);
/* PCR-18: Measure the DLME image entry point. */
dlme_img_ep = DL_ARGS_GET_DLME_ENTRY_POINT(a);
drtm_event_log_measure_and_record((uintptr_t)&dlme_img_ep,
sizeof(dlme_img_ep),
DRTM_EVENT_ARM_DLME_EP, NULL,
PCR_18);
CHECK_RC(rc, drtm_event_log_measure_and_record(DRTM_EVENT_ARM_DLME_EP));
/* PCR-18: End of DCE measurements. */
rc = drtm_event_log_measure_and_record((uintptr_t)drtm_event_arm_sep_data,
strlen(drtm_event_arm_sep_data),
DRTM_EVENT_ARM_SEPARATOR, NULL,
PCR_18);
CHECK_RC(rc,
drtm_event_log_measure_and_record(DRTM_EVENT_ARM_SEPARATOR));
/*
* If the DCE is unable to log a measurement because there is no available
* space in the event log region, the DCE must extend a hash of the value
* 0xFF (1 byte in size) into PCR[17] and PCR[18] and enter remediation.
*/
return SUCCESS;
}
void drtm_serialise_event_log(uint8_t *dst, size_t *event_log_size_out)
{
*event_log_size_out = event_log_get_cur_size(drtm_event_log);
memcpy(dst, drtm_event_log, *event_log_size_out);
}
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