lib/efi_loader/efi_tcg2.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Defines APIs that allow an OS to interact with UEFI firmware to query
 * information about the device.
 * https://trustedcomputinggroup.org/resource/tcg-efi-protocol-specification/
 *
 * Copyright (c) 2020, Linaro Limited
 */

#define LOG_CATEGORY LOGC_EFI
#include <common.h>
#include <dm.h>
#include <efi_loader.h>
#include <efi_tcg2.h>
#include <log.h>
#include <version.h>
#include <tpm-v2.h>
#include <u-boot/sha1.h>
#include <u-boot/sha256.h>
#include <u-boot/sha512.h>
#include <linux/unaligned/access_ok.h>
#include <linux/unaligned/generic.h>
#include <hexdump.h>

struct event_log_buffer {
	void *buffer;
	void *final_buffer;
	size_t pos; /* eventlog position */
	size_t final_pos; /* final events config table position */
	size_t last_event_size;
	bool get_event_called;
	bool truncated;
};

static struct event_log_buffer event_log;
/*
 * When requesting TPM2_CAP_TPM_PROPERTIES the value is on a standard offset.
 * Since the current tpm2_get_capability() response buffers starts at
 * 'union tpmu_capabilities data' of 'struct tpms_capability_data', calculate
 * the response size and offset once for all consumers
 */
#define TPM2_RESPONSE_BUFFER_SIZE (sizeof(struct tpms_capability_data) - \
				   offsetof(struct tpms_capability_data, data))
#define properties_offset (offsetof(struct tpml_tagged_tpm_property, tpm_property) + \
			   offsetof(struct tpms_tagged_property, value))

static const efi_guid_t efi_guid_tcg2_protocol = EFI_TCG2_PROTOCOL_GUID;
static const efi_guid_t efi_guid_final_events = EFI_TCG2_FINAL_EVENTS_TABLE_GUID;

struct digest_info {
	u16 hash_alg;
	u32 hash_mask;
	u16 hash_len;
};

const static struct digest_info hash_algo_list[] = {
	{
		TPM2_ALG_SHA1,
		EFI_TCG2_BOOT_HASH_ALG_SHA1,
		TPM2_SHA1_DIGEST_SIZE,
	},
	{
		TPM2_ALG_SHA256,
		EFI_TCG2_BOOT_HASH_ALG_SHA256,
		TPM2_SHA256_DIGEST_SIZE,
	},
	{
		TPM2_ALG_SHA384,
		EFI_TCG2_BOOT_HASH_ALG_SHA384,
		TPM2_SHA384_DIGEST_SIZE,
	},
	{
		TPM2_ALG_SHA512,
		EFI_TCG2_BOOT_HASH_ALG_SHA512,
		TPM2_SHA512_DIGEST_SIZE,
	},
};

#define MAX_HASH_COUNT ARRAY_SIZE(hash_algo_list)

/**
 * alg_to_mask - Get a TCG hash mask for algorithms
 *
 * @hash_alg: TCG defined algorithm
 *
 * @Return: TCG hashing algorithm bitmaps, 0 if the algorithm is not supported
 */
static u32 alg_to_mask(u16 hash_alg)
{
	int i;

	for (i = 0; i < MAX_HASH_COUNT; i++) {
		if (hash_algo_list[i].hash_alg == hash_alg)
			return hash_algo_list[i].hash_mask;
	}

	return 0;
}

/**
 * alg_to_len - Get a TCG hash len for algorithms
 *
 * @hash_alg: TCG defined algorithm
 *
 * @Return: len of chosen algorithm, 0 if the algorithm is not supported
 */
static u16 alg_to_len(u16 hash_alg)
{
	int i;

	for (i = 0; i < MAX_HASH_COUNT; i++) {
		if (hash_algo_list[i].hash_alg == hash_alg)
			return hash_algo_list[i].hash_len;
	}

	return 0;
}

static u32 tcg_event_final_size(struct tpml_digest_values *digest_list)
{
	u32 len;
	int i;

	len = offsetof(struct tcg_pcr_event2, digests);
	len += offsetof(struct tpml_digest_values, digests);
	for (i = 0; i < digest_list->count; i++) {
		u16 hash_alg = digest_list->digests[i].hash_alg;

		len += offsetof(struct tpmt_ha, digest);
		len += alg_to_len(hash_alg);
	}
	len += sizeof(u32); /* tcg_pcr_event2 event_size*/

	return len;
}

/* tcg2_pcr_extend - Extend PCRs for a TPM2 device for a given tpml_digest_values
 *
 * @dev:		device
 * @digest_list:	list of digest algorithms to extend
 *
 * @Return: status code
 */
static efi_status_t tcg2_pcr_extend(struct udevice *dev, u32 pcr_index,
				    struct tpml_digest_values *digest_list)
{
	u32 rc;
	int i;

	for (i = 0; i < digest_list->count; i++) {
		u32 alg = digest_list->digests[i].hash_alg;

		rc = tpm2_pcr_extend(dev, pcr_index, alg,
				     (u8 *)&digest_list->digests[i].digest,
				     alg_to_len(alg));
		if (rc) {
			EFI_PRINT("Failed to extend PCR\n");
			return EFI_DEVICE_ERROR;
		}
	}

	return EFI_SUCCESS;
}

/* tcg2_agile_log_append - Append an agile event to out eventlog
 *
 * @pcr_index:		PCR index
 * @event_type:		type of event added
 * @digest_list:	list of digest algorithms to add
 * @size:		size of event
 * @event:		event to add
 *
 * @Return: status code
 */
static efi_status_t tcg2_agile_log_append(u32 pcr_index, u32 event_type,
					  struct tpml_digest_values *digest_list,
					  u32 size, u8 event[])
{
	void *log = (void *)((uintptr_t)event_log.buffer + event_log.pos);
	size_t pos;
	int i;
	u32 event_size;

	if (event_log.get_event_called)
		log = (void *)((uintptr_t)event_log.final_buffer +
			       event_log.final_pos);

	/*
	 * size refers to the length of event[] only, we need to check against
	 * the final tcg_pcr_event2 size
	 */
	event_size = size + tcg_event_final_size(digest_list);
	if (event_log.pos + event_size > TPM2_EVENT_LOG_SIZE ||
	    event_log.final_pos + event_size > TPM2_EVENT_LOG_SIZE) {
		event_log.truncated = true;
		return EFI_VOLUME_FULL;
	}

	put_unaligned_le32(pcr_index, log);
	pos = offsetof(struct tcg_pcr_event2, event_type);
	put_unaligned_le32(event_type, (void *)((uintptr_t)log + pos));
	pos = offsetof(struct tcg_pcr_event2, digests); /* count */
	put_unaligned_le32(digest_list->count, (void *)((uintptr_t)log + pos));

	pos += offsetof(struct tpml_digest_values, digests);
	for (i = 0; i < digest_list->count; i++) {
		u16 hash_alg = digest_list->digests[i].hash_alg;
		u8 *digest = (u8 *)&digest_list->digests[i].digest;

		put_unaligned_le16(hash_alg, (void *)((uintptr_t)log + pos));
		pos += offsetof(struct tpmt_ha, digest);
		memcpy((void *)((uintptr_t)log + pos), digest, alg_to_len(hash_alg));
		pos += alg_to_len(hash_alg);
	}

	put_unaligned_le32(size, (void *)((uintptr_t)log + pos));
	pos += sizeof(u32); /* tcg_pcr_event2 event_size*/
	memcpy((void *)((uintptr_t)log + pos), event, size);
	pos += size;

	/* make sure the calculated buffer is what we checked against */
	if (pos != event_size)
		return EFI_INVALID_PARAMETER;

	/* if GetEventLog hasn't been called update the normal log */
	if (!event_log.get_event_called) {
		event_log.pos += pos;
		event_log.last_event_size = pos;
	} else {
	/* if GetEventLog has been called update config table log */
		struct efi_tcg2_final_events_table *final_event;

		final_event =
			(struct efi_tcg2_final_events_table *)(event_log.final_buffer);
		final_event->number_of_events++;
		event_log.final_pos += pos;
	}

	return EFI_SUCCESS;
}

/**
 * platform_get_tpm_device() - retrieve TPM device
 *
 * This function retrieves the udevice implementing a TPM
 *
 * This function may be overridden if special initialization is needed.
 *
 * @dev:	udevice
 * Return:	status code
 */
__weak efi_status_t platform_get_tpm2_device(struct udevice **dev)
{
	for_each_tpm_device(*dev) {
		/* Only support TPMv2 devices */
		if (tpm_get_version(*dev) == TPM_V2)
			return EFI_SUCCESS;
	}

	return EFI_NOT_FOUND;
}

/**
 * tpm2_get_max_command_size() - get the supported max command size
 *
 * @dev:		TPM device
 * @max_command_size:	output buffer for the size
 *
 * Return: 0 on success, -1 on error
 */
static int tpm2_get_max_command_size(struct udevice *dev, u16 *max_command_size)
{
	u8 response[TPM2_RESPONSE_BUFFER_SIZE];
	u32 ret;

	memset(response, 0, sizeof(response));
	ret = tpm2_get_capability(dev, TPM2_CAP_TPM_PROPERTIES,
				  TPM2_PT_MAX_COMMAND_SIZE, response, 1);
	if (ret)
		return -1;

	*max_command_size = (uint16_t)get_unaligned_be32(response +
							 properties_offset);

	return 0;
}

/**
 * tpm2_get_max_response_size() - get the supported max response size
 *
 * @dev:		TPM device
 * @max_response_size:	output buffer for the size
 *
 * Return: 0 on success, -1 on error
 */
static int tpm2_get_max_response_size(struct udevice *dev,
				      u16 *max_response_size)
{
	u8 response[TPM2_RESPONSE_BUFFER_SIZE];
	u32 ret;

	memset(response, 0, sizeof(response));
	ret = tpm2_get_capability(dev, TPM2_CAP_TPM_PROPERTIES,
				  TPM2_PT_MAX_RESPONSE_SIZE, response, 1);
	if (ret)
		return -1;

	*max_response_size = (uint16_t)get_unaligned_be32(response +
							  properties_offset);

	return 0;
}

/**
 * tpm2_get_manufacturer_id() - get the manufacturer ID
 *
 * @dev:		TPM device
 * @manufacturer_id:	output buffer for the id
 *
 * Return: 0 on success, -1 on error
 */
static int tpm2_get_manufacturer_id(struct udevice *dev, u32 *manufacturer_id)
{
	u8 response[TPM2_RESPONSE_BUFFER_SIZE];
	u32 ret;

	memset(response, 0, sizeof(response));
	ret = tpm2_get_capability(dev, TPM2_CAP_TPM_PROPERTIES,
				  TPM2_PT_MANUFACTURER, response, 1);
	if (ret)
		return -1;

	*manufacturer_id = get_unaligned_be32(response + properties_offset);

	return 0;
}

/**
 * tpm2_get_num_pcr() - get the number of PCRs
 *
 * @dev:		TPM device
 * @manufacturer_id:	output buffer for the number
 *
 * Return: 0 on success, -1 on error
 */
static int tpm2_get_num_pcr(struct udevice *dev, u32 *num_pcr)
{
	u8 response[TPM2_RESPONSE_BUFFER_SIZE];
	u32 ret;

	memset(response, 0, sizeof(response));
	ret = tpm2_get_capability(dev, TPM2_CAP_TPM_PROPERTIES,
				  TPM2_PT_PCR_COUNT, response, 1);
	if (ret)
		return -1;

	*num_pcr = get_unaligned_be32(response + properties_offset);
	if (*num_pcr > TPM2_MAX_PCRS)
		return -1;

	return 0;
}

/**
 * is_active_pcr() - Check if a supported algorithm is active
 *
 * @dev:		TPM device
 * @selection:		struct of PCR information
 *
 * Return: true if PCR is active
 */
static bool is_active_pcr(struct tpms_pcr_selection *selection)
{
	int i;
	/*
	 * check the pcr_select. If at least one of the PCRs supports the
	 * algorithm add it on the active ones
	 */
	for (i = 0; i < selection->size_of_select; i++) {
		if (selection->pcr_select[i])
			return true;
	}

	return false;
}

/**
 * tpm2_get_pcr_info() - get the supported, active PCRs and number of banks
 *
 * @dev:		TPM device
 * @supported_pcr:	bitmask with the algorithms supported
 * @active_pcr:		bitmask with the active algorithms
 * @pcr_banks:		number of PCR banks
 *
 * Return: 0 on success, -1 on error
 */
static int tpm2_get_pcr_info(struct udevice *dev, u32 *supported_pcr,
			     u32 *active_pcr, u32 *pcr_banks)
{
	u8 response[TPM2_RESPONSE_BUFFER_SIZE];
	struct tpml_pcr_selection pcrs;
	u32 ret, num_pcr;
	int i, tpm_ret;

	memset(response, 0, sizeof(response));
	ret = tpm2_get_capability(dev, TPM2_CAP_PCRS, 0, response, 1);
	if (ret)
		goto out;

	pcrs.count = get_unaligned_be32(response);
	/*
	 * We only support 5 algorithms for now so check against that
	 * instead of TPM2_NUM_PCR_BANKS
	 */
	if (pcrs.count > MAX_HASH_COUNT || pcrs.count < 1)
		goto out;

	tpm_ret = tpm2_get_num_pcr(dev, &num_pcr);
	if (tpm_ret)
		goto out;

	for (i = 0; i < pcrs.count; i++) {
		/*
		 * Definition of TPMS_PCR_SELECTION Structure
		 * hash: u16
		 * size_of_select: u8
		 * pcr_select: u8 array
		 *
		 * The offsets depend on the number of the device PCRs
		 * so we have to calculate them based on that
		 */
		u32 hash_offset = offsetof(struct tpml_pcr_selection, selection) +
			i * offsetof(struct tpms_pcr_selection, pcr_select) +
			i * ((num_pcr + 7) / 8);
		u32 size_select_offset =
			hash_offset + offsetof(struct tpms_pcr_selection,
					       size_of_select);
		u32 pcr_select_offset =
			hash_offset + offsetof(struct tpms_pcr_selection,
					       pcr_select);

		pcrs.selection[i].hash =
			get_unaligned_be16(response + hash_offset);
		pcrs.selection[i].size_of_select =
			__get_unaligned_be(response + size_select_offset);
		if (pcrs.selection[i].size_of_select > TPM2_PCR_SELECT_MAX)
			goto out;
		/* copy the array of pcr_select */
		memcpy(pcrs.selection[i].pcr_select, response + pcr_select_offset,
		       pcrs.selection[i].size_of_select);
	}

	for (i = 0; i < pcrs.count; i++) {
		u32 hash_mask = alg_to_mask(pcrs.selection[i].hash);

		if (hash_mask) {
			*supported_pcr |= hash_mask;
			if (is_active_pcr(&pcrs.selection[i]))
				*active_pcr |= hash_mask;
		} else {
			EFI_PRINT("Unknown algorithm %x\n", pcrs.selection[i].hash);
		}
	}

	*pcr_banks = pcrs.count;

	return 0;
out:
	return -1;
}

/**
 * __get_active_pcr_banks() - returns the currently active PCR banks
 *
 * @active_pcr_banks:		pointer for receiving the bitmap of currently
 *				active PCR banks
 *
 * Return:	status code
 */
static efi_status_t __get_active_pcr_banks(u32 *active_pcr_banks)
{
	struct udevice *dev;
	u32 active, supported, pcr_banks;
	efi_status_t ret;
	int err;

	ret = platform_get_tpm2_device(&dev);
	if (ret != EFI_SUCCESS)
		goto out;

	err = tpm2_get_pcr_info(dev, &supported, &active, &pcr_banks);
	if (err) {
		ret = EFI_DEVICE_ERROR;
		goto out;
	}

	*active_pcr_banks = active;

out:
	return ret;
}

/* tcg2_create_digest - create a list of digests of the supported PCR banks
 *			for a given memory range
 *
 * @input:		input memory
 * @length:		length of buffer to calculate the digest
 * @digest_list:	list of digests to fill in
 *
 * Return:		status code
 */
static efi_status_t tcg2_create_digest(const u8 *input, u32 length,
				       struct tpml_digest_values *digest_list)
{
	sha1_context ctx;
	sha256_context ctx_256;
	sha512_context ctx_512;
	u8 final[TPM2_ALG_SHA512];
	efi_status_t ret;
	u32 active;
	int i;

	ret = __get_active_pcr_banks(&active);
	if (ret != EFI_SUCCESS)
		return ret;

	digest_list->count = 0;
	for (i = 0; i < MAX_HASH_COUNT; i++) {
		u16 hash_alg = hash_algo_list[i].hash_alg;

		if (!(active & alg_to_mask(hash_alg)))
			continue;
		switch (hash_alg) {
		case TPM2_ALG_SHA1:
			sha1_starts(&ctx);
			sha1_update(&ctx, input, length);
			sha1_finish(&ctx, final);
			digest_list->count++;
			break;
		case TPM2_ALG_SHA256:
			sha256_starts(&ctx_256);
			sha256_update(&ctx_256, input, length);
			sha256_finish(&ctx_256, final);
			digest_list->count++;
			break;
		case TPM2_ALG_SHA384:
			sha384_starts(&ctx_512);
			sha384_update(&ctx_512, input, length);
			sha384_finish(&ctx_512, final);
			digest_list->count++;
			break;
		case TPM2_ALG_SHA512:
			sha512_starts(&ctx_512);
			sha512_update(&ctx_512, input, length);
			sha512_finish(&ctx_512, final);
			digest_list->count++;
			break;
		default:
			EFI_PRINT("Unsupported algorithm %x\n", hash_alg);
			return EFI_INVALID_PARAMETER;
		}
		digest_list->digests[i].hash_alg = hash_alg;
		memcpy(&digest_list->digests[i].digest, final, (u32)alg_to_len(hash_alg));
	}

	return EFI_SUCCESS;
}

/**
 * efi_tcg2_get_capability() - protocol capability information and state information
 *
 * @this:		TCG2 protocol instance
 * @capability:		caller allocated memory with size field to the size of
 *			the structure allocated

 * Return:	status code
 */
static efi_status_t EFIAPI
efi_tcg2_get_capability(struct efi_tcg2_protocol *this,
			struct efi_tcg2_boot_service_capability *capability)
{
	struct udevice *dev;
	efi_status_t efi_ret;
	int ret;

	EFI_ENTRY("%p, %p", this, capability);

	if (!this || !capability) {
		efi_ret = EFI_INVALID_PARAMETER;
		goto out;
	}

	if (capability->size < boot_service_capability_min) {
		capability->size = boot_service_capability_min;
		efi_ret = EFI_BUFFER_TOO_SMALL;
		goto out;
	}

	if (capability->size < sizeof(*capability)) {
		capability->size = sizeof(*capability);
		efi_ret = EFI_BUFFER_TOO_SMALL;
		goto out;
	}

	capability->structure_version.major = 1;
	capability->structure_version.minor = 1;
	capability->protocol_version.major = 1;
	capability->protocol_version.minor = 1;

	efi_ret = platform_get_tpm2_device(&dev);
	if (efi_ret != EFI_SUCCESS) {
		capability->supported_event_logs = 0;
		capability->hash_algorithm_bitmap = 0;
		capability->tpm_present_flag = false;
		capability->max_command_size = 0;
		capability->max_response_size = 0;
		capability->manufacturer_id = 0;
		capability->number_of_pcr_banks = 0;
		capability->active_pcr_banks = 0;

		efi_ret = EFI_SUCCESS;
		goto out;
	}

	/* We only allow a TPMv2 device to register the EFI protocol */
	capability->supported_event_logs = TCG2_EVENT_LOG_FORMAT_TCG_2;

	capability->tpm_present_flag = true;

	/* Supported and active PCRs */
	capability->hash_algorithm_bitmap = 0;
	capability->active_pcr_banks = 0;
	ret = tpm2_get_pcr_info(dev, &capability->hash_algorithm_bitmap,
				&capability->active_pcr_banks,
				&capability->number_of_pcr_banks);
	if (ret) {
		efi_ret = EFI_DEVICE_ERROR;
		goto out;
	}

	/* Max command size */
	ret = tpm2_get_max_command_size(dev, &capability->max_command_size);
	if (ret) {
		efi_ret = EFI_DEVICE_ERROR;
		goto out;
	}

	/* Max response size */
	ret = tpm2_get_max_response_size(dev, &capability->max_response_size);
	if (ret) {
		efi_ret = EFI_DEVICE_ERROR;
		goto out;
	}

	/* Manufacturer ID */
	ret = tpm2_get_manufacturer_id(dev, &capability->manufacturer_id);
	if (ret) {
		efi_ret = EFI_DEVICE_ERROR;
		goto out;
	}

	return EFI_EXIT(EFI_SUCCESS);
out:
	return EFI_EXIT(efi_ret);
}

/**
 * efi_tcg2_get_eventlog() -	retrieve the the address of an event log and its
 *				last entry
 *
 * @this:			TCG2 protocol instance
 * @log_format:			type of event log format
 * @event_log_location:		pointer to the memory address of the event log
 * @event_log_last_entry:	pointer to the address of the start of the last
 *				entry in the event log in memory, if log contains
 *				more than 1 entry
 * @event_log_truncated:	set to true, if the Event Log is missing at i
 *				least one entry
 *
 * Return:	status code
 */
static efi_status_t EFIAPI
efi_tcg2_get_eventlog(struct efi_tcg2_protocol *this,
		      efi_tcg_event_log_format log_format,
		      u64 *event_log_location, u64 *event_log_last_entry,
		      bool *event_log_truncated)
{
	efi_status_t ret = EFI_SUCCESS;
	struct udevice *dev;

	EFI_ENTRY("%p, %u, %p, %p,  %p", this, log_format, event_log_location,
		  event_log_last_entry, event_log_truncated);

	ret = platform_get_tpm2_device(&dev);
	if (ret != EFI_SUCCESS) {
		event_log_location = NULL;
		event_log_last_entry = NULL;
		*event_log_truncated = false;
		ret = EFI_SUCCESS;
		goto out;
	}
	*event_log_location = (uintptr_t)event_log.buffer;
	*event_log_last_entry = (uintptr_t)(event_log.buffer + event_log.pos -
					    event_log.last_event_size);
	*event_log_truncated = event_log.truncated;
	event_log.get_event_called = true;

out:
	return EFI_EXIT(ret);
}

/**
 * efi_tcg2_hash_log_extend_event() - extend and optionally log events
 *
 * @this:			TCG2 protocol instance
 * @flags:			bitmap providing additional information on the
 *				operation
 * @data_to_hash:		physical address of the start of the data buffer
 *				to be hashed
 * @data_to_hash_len:		the length in bytes of the buffer referenced by
 *				data_to_hash
 * @efi_tcg_event:		pointer to data buffer containing information
 *				about the event
 *
 * Return:	status code
 */
static efi_status_t EFIAPI
efi_tcg2_hash_log_extend_event(struct efi_tcg2_protocol *this, u64 flags,
			       u64 data_to_hash, u64 data_to_hash_len,
			       struct efi_tcg2_event *efi_tcg_event)
{
	struct udevice *dev;
	efi_status_t ret;
	u32 event_type, pcr_index, event_size;
	struct tpml_digest_values digest_list;

	EFI_ENTRY("%p, %llu, %llu, %llu, %p", this, flags, data_to_hash,
		  data_to_hash_len, efi_tcg_event);

	if (!this || !data_to_hash || !efi_tcg_event) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}

	ret = platform_get_tpm2_device(&dev);
	if (ret != EFI_SUCCESS)
		goto out;

	if (efi_tcg_event->size < efi_tcg_event->header.header_size +
	    sizeof(u32)) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}

	if (efi_tcg_event->header.pcr_index < 0 ||
	    efi_tcg_event->header.pcr_index > TPM2_MAX_PCRS) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}

	/*
	 * if PE_COFF_IMAGE is set we need to make sure the image is not
	 * corrupted, verify it and hash the PE/COFF image in accordance with
	 * the  procedure  specified  in  "Calculating  the  PE  Image  Hash"
	 * section  of the "Windows Authenticode Portable Executable Signature
	 * Format"
	 * Not supported for now
	 */
	if (flags & PE_COFF_IMAGE) {
		ret = EFI_UNSUPPORTED;
		goto out;
	}

	pcr_index = efi_tcg_event->header.pcr_index;
	event_type = efi_tcg_event->header.event_type;

	ret = tcg2_create_digest((u8 *)data_to_hash, data_to_hash_len,
				 &digest_list);
	if (ret != EFI_SUCCESS)
		goto out;

	ret = tcg2_pcr_extend(dev, pcr_index, &digest_list);
	if (ret != EFI_SUCCESS)
		goto out;

	if (flags & EFI_TCG2_EXTEND_ONLY) {
		if (event_log.truncated)
			ret = EFI_VOLUME_FULL;
		goto out;
	}

	/*
	 * The efi_tcg_event size includes the size component and the
	 * headersize
	 */
	event_size = efi_tcg_event->size - sizeof(efi_tcg_event->size) -
		efi_tcg_event->header.header_size;
	ret = tcg2_agile_log_append(pcr_index, event_type, &digest_list,
				    event_size, efi_tcg_event->event);
out:
	return EFI_EXIT(ret);
}

/**
 * efi_tcg2_submit_command() - Send command to the TPM
 *
 * @this:			TCG2 protocol instance
 * @input_param_block_size:	size of the TPM input parameter block
 * @input_param_block:		pointer to the TPM input parameter block
 * @output_param_block_size:	size of the TPM output parameter block
 * @output_param_block:		pointer to the TPM output parameter block
 *
 * Return:	status code
 */
static efi_status_t EFIAPI
efi_tcg2_submit_command(struct efi_tcg2_protocol *this,
			u32 input_param_block_size, u8 *input_param_block,
			u32 output_param_block_size, u8 *output_param_block)
{
	return EFI_UNSUPPORTED;
}

/**
 * efi_tcg2_get_active_pcr_banks() - returns the currently active PCR banks
 *
 * @this:			TCG2 protocol instance
 * @active_pcr_banks:		pointer for receiving the bitmap of currently
 *				active PCR banks
 *
 * Return:	status code
 */
static efi_status_t EFIAPI
efi_tcg2_get_active_pcr_banks(struct efi_tcg2_protocol *this,
			      u32 *active_pcr_banks)
{
	efi_status_t ret;

	EFI_ENTRY("%p, %p", this, active_pcr_banks);
	ret = __get_active_pcr_banks(active_pcr_banks);

	return EFI_EXIT(ret);
}

/**
 * efi_tcg2_set_active_pcr_banks() - sets the currently active PCR banks
 *
 * @this:			TCG2 protocol instance
 * @active_pcr_banks:		bitmap of the requested active PCR banks
 *
 * Return:	status code
 */
static efi_status_t EFIAPI
efi_tcg2_set_active_pcr_banks(struct efi_tcg2_protocol *this,
			      u32 active_pcr_banks)
{
	return EFI_UNSUPPORTED;
}

/**
 * efi_tcg2_get_result_of_set_active_pcr_banks() - retrieve result for previous
 *						   set_active_pcr_banks()
 *
 * @this:			TCG2 protocol instance
 * @operation_present:		non-zero value to indicate a
 *				set_active_pcr_banks operation was
 *				invoked during last boot
 * @response:			result value could be returned
 *
 * Return:	status code
 */
static efi_status_t EFIAPI
efi_tcg2_get_result_of_set_active_pcr_banks(struct efi_tcg2_protocol *this,
					    u32 *operation_present, u32 *response)
{
	return EFI_UNSUPPORTED;
}

static const struct efi_tcg2_protocol efi_tcg2_protocol = {
	.get_capability = efi_tcg2_get_capability,
	.get_eventlog = efi_tcg2_get_eventlog,
	.hash_log_extend_event = efi_tcg2_hash_log_extend_event,
	.submit_command = efi_tcg2_submit_command,
	.get_active_pcr_banks = efi_tcg2_get_active_pcr_banks,
	.set_active_pcr_banks = efi_tcg2_set_active_pcr_banks,
	.get_result_of_set_active_pcr_banks = efi_tcg2_get_result_of_set_active_pcr_banks,
};

/**
 * create_specid_event() - Create the first event in the eventlog
 *
 * @dev:			tpm device
 * @event_header:		Pointer to the final event header
 * @event_size:			final spec event size
 *
 * Return:	status code
 */
static efi_status_t create_specid_event(struct udevice *dev, void *buffer,
					size_t *event_size)
{
	struct tcg_efi_spec_id_event *spec_event;
	size_t spec_event_size;
	efi_status_t ret = EFI_DEVICE_ERROR;
	u32 active, supported;
	int err, i;

	/*
	 * Create Spec event. This needs to be the first event in the log
	 * according to the TCG EFI protocol spec
	 */

	/* Setup specID event data */
	spec_event = (struct tcg_efi_spec_id_event *)buffer;
	memcpy(spec_event->signature, TCG_EFI_SPEC_ID_EVENT_SIGNATURE_03,
	       sizeof(spec_event->signature));
	put_unaligned_le32(0, &spec_event->platform_class); /* type client */
	spec_event->spec_version_minor =
		TCG_EFI_SPEC_ID_EVENT_SPEC_VERSION_MINOR_TPM2;
	spec_event->spec_version_major =
		TCG_EFI_SPEC_ID_EVENT_SPEC_VERSION_MAJOR_TPM2;
	spec_event->spec_errata =
		TCG_EFI_SPEC_ID_EVENT_SPEC_VERSION_ERRATA_TPM2;
	spec_event->uintn_size = sizeof(efi_uintn_t) / sizeof(u32);

	err = tpm2_get_pcr_info(dev, &supported, &active,
				&spec_event->number_of_algorithms);
	if (err)
		goto out;
	if (spec_event->number_of_algorithms > MAX_HASH_COUNT ||
	    spec_event->number_of_algorithms < 1)
		goto out;

	for (i = 0; i < spec_event->number_of_algorithms; i++) {
		u16 hash_alg = hash_algo_list[i].hash_alg;
		u16 hash_len = hash_algo_list[i].hash_len;

		if (active && alg_to_mask(hash_alg)) {
			put_unaligned_le16(hash_alg,
					   &spec_event->digest_sizes[i].algorithm_id);
			put_unaligned_le16(hash_len,
					   &spec_event->digest_sizes[i].digest_size);
		}
	}
	/*
	 * the size of the spec event and placement of vendor_info_size
	 * depends on supported algoriths
	 */
	spec_event_size =
		offsetof(struct tcg_efi_spec_id_event, digest_sizes) +
		spec_event->number_of_algorithms * sizeof(spec_event->digest_sizes[0]);
	/* no vendor info for us */
	memset(buffer + spec_event_size, 0,
	       sizeof(spec_event->vendor_info_size));
	spec_event_size += sizeof(spec_event->vendor_info_size);
	*event_size = spec_event_size;

	return EFI_SUCCESS;

out:
	return ret;
}

/**
 * tcg2_uninit - remove the final event table and free efi memory on failures
 */
void tcg2_uninit(void)
{
	efi_status_t ret;

	ret = efi_install_configuration_table(&efi_guid_final_events, NULL);
	if (ret != EFI_SUCCESS)
		log_err("Failed to delete final events config table\n");

	efi_free_pool(event_log.buffer);
	event_log.buffer = NULL;
	efi_free_pool(event_log.final_buffer);
	event_log.final_buffer = NULL;
}

/**
 * create_final_event() - Create the final event and install the config
 *			defined by the TCG EFI spec
 */
static efi_status_t create_final_event(void)
{
	struct efi_tcg2_final_events_table *final_event;
	efi_status_t ret;

	/*
	 * All events generated after the invocation of
	 * EFI_TCG2_GET_EVENT_LOGS need to be stored in an instance of an
	 * EFI_CONFIGURATION_TABLE
	 */
	ret = efi_allocate_pool(EFI_ACPI_MEMORY_NVS, TPM2_EVENT_LOG_SIZE,
				&event_log.final_buffer);
	if (ret != EFI_SUCCESS)
		goto out;

	memset(event_log.final_buffer, 0xff, TPM2_EVENT_LOG_SIZE);
	final_event = event_log.final_buffer;
	final_event->number_of_events = 0;
	final_event->version = EFI_TCG2_FINAL_EVENTS_TABLE_VERSION;
	event_log.final_pos = sizeof(*final_event);
	ret = efi_install_configuration_table(&efi_guid_final_events,
					      final_event);
out:
	return ret;
}

/**
 * efi_init_event_log() - initialize an eventlog
 */
static efi_status_t efi_init_event_log(void)
{
	/*
	 * vendor_info_size is currently set to 0, we need to change the length
	 * and allocate the flexible array member if this changes
	 */
	struct tcg_pcr_event *event_header = NULL;
	struct udevice *dev;
	size_t spec_event_size;
	efi_status_t ret;

	ret = platform_get_tpm2_device(&dev);
	if (ret != EFI_SUCCESS)
		goto out;

	ret = efi_allocate_pool(EFI_BOOT_SERVICES_DATA, TPM2_EVENT_LOG_SIZE,
				(void **)&event_log.buffer);
	if (ret != EFI_SUCCESS)
		goto out;

	/*
	 * initialize log area as 0xff so the OS can easily figure out the
	 * last log entry
	 */
	memset(event_log.buffer, 0xff, TPM2_EVENT_LOG_SIZE);
	event_log.pos = 0;
	event_log.last_event_size = 0;
	event_log.get_event_called = false;
	event_log.truncated = false;

	/*
	 * The log header is defined to be in SHA1 event log entry format.
	 * Setup event header
	 */
	event_header =  (struct tcg_pcr_event *)event_log.buffer;
	put_unaligned_le32(0, &event_header->pcr_index);
	put_unaligned_le32(EV_NO_ACTION, &event_header->event_type);
	memset(&event_header->digest, 0, sizeof(event_header->digest));
	ret = create_specid_event(dev, (void *)((uintptr_t)event_log.buffer + sizeof(*event_header)),
				  &spec_event_size);
	if (ret != EFI_SUCCESS)
		goto out;
	put_unaligned_le32(spec_event_size, &event_header->event_size);
	event_log.pos = spec_event_size + sizeof(*event_header);
	event_log.last_event_size = event_log.pos;

	ret = create_final_event();
	if (ret != EFI_SUCCESS)
		goto out;

	return EFI_SUCCESS;
out:
	tcg2_uninit();
	return ret;
}

/**
 * efi_append_scrtm_version - Append an S-CRTM EV_S_CRTM_VERSION event on the
 *			      eventlog and extend the PCRs
 *
 * @dev:	TPM device
 *
 * @Return:	status code
 */
static efi_status_t efi_append_scrtm_version(struct udevice *dev)
{
	struct tpml_digest_values digest_list;
	u8 ver[] = U_BOOT_VERSION_STRING;
	const int pcr_index = 0;
	efi_status_t ret;

	ret = tcg2_create_digest(ver, sizeof(ver), &digest_list);
	if (ret != EFI_SUCCESS)
		goto out;

	ret = tcg2_pcr_extend(dev, pcr_index, &digest_list);
	if (ret != EFI_SUCCESS)
		goto out;

	ret = tcg2_agile_log_append(pcr_index, EV_S_CRTM_VERSION, &digest_list,
				    sizeof(ver), ver);

out:
	return ret;
}

/**
 * efi_tcg2_register() - register EFI_TCG2_PROTOCOL
 *
 * If a TPM2 device is available, the TPM TCG2 Protocol is registered
 *
 * Return:	An error status is only returned if adding the protocol fails.
 */
efi_status_t efi_tcg2_register(void)
{
	efi_status_t ret = EFI_SUCCESS;
	struct udevice *dev;

	ret = platform_get_tpm2_device(&dev);
	if (ret != EFI_SUCCESS) {
		log_warning("Unable to find TPMv2 device\n");
		ret = EFI_SUCCESS;
		goto out;
	}

	ret = efi_init_event_log();
	if (ret != EFI_SUCCESS)
		goto fail;

	ret = efi_append_scrtm_version(dev);
	if (ret != EFI_SUCCESS)
		goto out;

	ret = efi_add_protocol(efi_root, &efi_guid_tcg2_protocol,
			       (void *)&efi_tcg2_protocol);
	if (ret != EFI_SUCCESS) {
		log_err("Cannot install EFI_TCG2_PROTOCOL\n");
		goto fail;
	}

out:
	return ret;
fail:
	tcg2_uninit();
	return ret;
}