core/pta/attestation.c

// SPDX-License-Identifier: BSD-2-Clause
/*
 * Copyright (C) 2021, Huawei Technologies Co., Ltd
 */

#include <config.h>
#include <crypto/crypto.h>
#include <kernel/linker.h>
#include <kernel/pseudo_ta.h>
#include <kernel/ts_store.h>
#include <kernel/user_access.h>
#include <kernel/user_mode_ctx.h>
#include <mm/file.h>
#include <pta_attestation.h>
#include <stdlib.h>
#include <string.h>
#include <tee/entry_std.h>
#include <tee/tee_fs.h>
#include <tee/tee_pobj.h>
#include <tee/uuid.h>
#include <utee_defines.h>

#define PTA_NAME "attestation.pta"

#define MAX_KEY_SIZE 4096

static TEE_UUID pta_uuid = PTA_ATTESTATION_UUID;

static struct rsa_keypair *key;

static const uint8_t key_file_name[] = "key";

static TEE_Result allocate_key(void)
{
	assert(!key);

	key = calloc(1, sizeof(*key));
	if (!key)
		return TEE_ERROR_OUT_OF_MEMORY;

	COMPILE_TIME_ASSERT(CFG_ATTESTATION_PTA_KEY_SIZE <= MAX_KEY_SIZE);
	return crypto_acipher_alloc_rsa_keypair(key, MAX_KEY_SIZE);
}

static void free_key(void)
{
	crypto_acipher_free_rsa_keypair(key);
	free(key);
	key = NULL;
}

static TEE_Result generate_key(void)
{
	uint32_t e = TEE_U32_TO_BIG_ENDIAN(65537);
	TEE_Result res = TEE_ERROR_GENERIC;

	res = allocate_key();
	if (res)
		goto err;

	res = crypto_bignum_bin2bn((uint8_t *)&e, sizeof(e), key->e);
	if (res)
		goto err;

	/*
	 * For security reasons, the RSA modulus size has to be at least the
	 * size of the data to be signed.
	 */
	DMSG("Generating %u bit RSA key pair", CFG_ATTESTATION_PTA_KEY_SIZE);
	COMPILE_TIME_ASSERT(CFG_ATTESTATION_PTA_KEY_SIZE >=
			    TEE_SHA256_HASH_SIZE);
	res = crypto_acipher_gen_rsa_key(key, CFG_ATTESTATION_PTA_KEY_SIZE);
	if (!res)
		goto out;

err:
	free_key();
out:
	return res;
}

/*
 * Return values:
 * > 0 : Number of bytes written to buf
 *   0 : @sz too large (> UINT16_MAX) or @buf_sz too small
 */
static size_t serialize_bignum(uint8_t *buf, size_t buf_sz, struct bignum *bn)
{
	uint8_t *p = buf;
	size_t sz = crypto_bignum_num_bytes(bn);
	uint16_t val = TEE_U16_TO_BIG_ENDIAN(sz);
	size_t total_sz = sizeof(val) + sz;

	if (sz > UINT16_MAX || total_sz > buf_sz)
		return 0;

	memcpy(p, &val, sizeof(val));
	p += sizeof(val);

	crypto_bignum_bn2bin(bn, p);

	return total_sz;
}

static size_t bufsize(size_t e_sz, size_t d_sz, size_t n_sz)
{
	/*
	 * Serialized key pair is 3 bignums (e, p and n) plus their sizes
	 * encoded as uint16_t.
	 */
	return e_sz + d_sz + n_sz + 3 * sizeof(uint16_t);
}

static TEE_Result serialize_key(uint8_t *buf, size_t size)
{
	TEE_Result res = TEE_ERROR_GENERIC;
	uint8_t *p = buf;
	size_t needed_sz = 0;
	size_t e_sz = 0;
	size_t d_sz = 0;
	size_t n_sz = 0;
	size_t sz = 0;

	assert(key);

	e_sz = crypto_bignum_num_bytes(key->e);
	d_sz = crypto_bignum_num_bytes(key->d);
	n_sz = crypto_bignum_num_bytes(key->n);
	if (e_sz > UINT16_MAX || d_sz > UINT16_MAX || n_sz > UINT16_MAX)
		goto err;

	needed_sz = bufsize(e_sz, d_sz, n_sz);
	if (size < needed_sz)
		goto err;

	sz = serialize_bignum(p, needed_sz, key->e);
	if (!sz)
		goto err;
	p += sz;
	needed_sz -= sz;
	sz = serialize_bignum(p, needed_sz, key->d);
	if (!sz)
		goto err;
	p += sz;
	needed_sz -= sz;
	sz = serialize_bignum(p, needed_sz, key->n);
	if (!sz)
		goto err;
	needed_sz -= sz;
	assert(!needed_sz);

	return TEE_SUCCESS;
err:
	return res;
}

static size_t deserialize_bignum(uint8_t *buf, size_t max_sz, struct bignum *bn)
{
	TEE_Result res = TEE_ERROR_GENERIC;
	uint8_t *p = buf;
	uint16_t val = 0;
	size_t sz = 0;

	if (max_sz < sizeof(val))
		return 0;

	memcpy(&val, p, sizeof(val));
	sz = TEE_U16_FROM_BIG_ENDIAN(val);
	p += sizeof(val);
	max_sz -= sizeof(val);
	if (max_sz < sz)
		return 0;

	res = crypto_bignum_bin2bn(p, sz, bn);
	if (res)
		return 0;

	return sizeof(val) + sz;
}

static TEE_Result deserialize_key(uint8_t *buf, size_t buf_sz)
{
	TEE_Result res = TEE_ERROR_GENERIC;
	uint8_t *p = buf;
	size_t sz = 0;

	res = allocate_key();
	if (res)
		return res;

	sz = deserialize_bignum(p, buf_sz, key->e);
	if (!sz)
		goto err;
	p += sz;
	buf_sz -= sz;
	sz = deserialize_bignum(p, buf_sz, key->d);
	if (!sz)
		goto err;
	p += sz;
	buf_sz -= sz;
	sz = deserialize_bignum(p, buf_sz, key->n);
	if (!sz)
		goto err;

	return TEE_SUCCESS;
err:
	free_key();
	return TEE_ERROR_GENERIC;
}

static TEE_Result sec_storage_obj_read(TEE_UUID *uuid, uint32_t storage_id,
				       const uint8_t *obj_id,
				       size_t obj_id_len,
				       uint8_t *data, size_t *len,
				       size_t offset, uint32_t flags)
{
	const struct tee_file_operations *fops = NULL;
	TEE_Result res = TEE_ERROR_BAD_STATE;
	struct tee_file_handle *fh = NULL;
	struct tee_pobj *po = NULL;
	size_t file_size = 0;
	size_t read_len = 0;

	fops = tee_svc_storage_file_ops(storage_id);
	if (!fops)
		return TEE_ERROR_NOT_IMPLEMENTED;

	if (obj_id_len > TEE_OBJECT_ID_MAX_LEN)
		return TEE_ERROR_BAD_PARAMETERS;

	res = tee_pobj_get(uuid, (void *)obj_id, obj_id_len, flags,
			   TEE_POBJ_USAGE_OPEN, fops, &po);
	if (res)
		return res;

	res = po->fops->open(po, &file_size, &fh);
	if (res)
		goto out;

	read_len = *len;
	res = po->fops->read(fh, offset, data, NULL, &read_len);
	if (res == TEE_ERROR_CORRUPT_OBJECT) {
		EMSG("Object corrupt");
		po->fops->remove(po);
	} else if (!res) {
		*len = read_len;
	}

	po->fops->close(&fh);
out:
	tee_pobj_release(po);

	return res;
}

static TEE_Result sec_storage_obj_write(TEE_UUID *uuid, uint32_t storage_id,
					const uint8_t *obj_id,
					size_t obj_id_len,
					const uint8_t *data, size_t len,
					size_t offset, uint32_t flags)

{
	const struct tee_file_operations *fops = NULL;
	struct tee_file_handle *fh = NULL;
	TEE_Result res = TEE_SUCCESS;
	struct tee_pobj *po = NULL;

	fops = tee_svc_storage_file_ops(storage_id);
	if (!fops)
		return TEE_ERROR_NOT_IMPLEMENTED;

	if (obj_id_len > TEE_OBJECT_ID_MAX_LEN)
		return TEE_ERROR_BAD_PARAMETERS;

	res = tee_pobj_get(uuid, (void *)obj_id, obj_id_len, flags,
			   TEE_POBJ_USAGE_OPEN, fops, &po);
	if (res)
		return res;

	res = po->fops->open(po, NULL, &fh);
	if (res == TEE_ERROR_ITEM_NOT_FOUND)
		res = po->fops->create(po, false, NULL, 0, NULL, 0,
				       NULL, NULL, 0, &fh);
	if (!res) {
		res = po->fops->write(fh, offset, data, NULL, len);
		po->fops->close(&fh);
	}

	tee_pobj_release(po);

	return res;
}

static TEE_Result load_key(uint8_t *buf, size_t size)
{
	TEE_Result res = TEE_ERROR_GENERIC;

	DMSG("Loading RSA key pair from secure storage");
	res = sec_storage_obj_read(&pta_uuid, TEE_STORAGE_PRIVATE,
				   key_file_name, sizeof(key_file_name) - 1,
				   buf, &size, 0, TEE_DATA_FLAG_ACCESS_READ);
	if (res)
		return res;
	DMSG("Read %zu bytes", size);
	res = deserialize_key(buf, size);
	if (!res)
		DMSG("Loaded %zu bit key pair", crypto_bignum_num_bits(key->n));

	return res;
}

static TEE_Result write_key(uint8_t *buf, size_t size)
{
	TEE_Result res = TEE_ERROR_GENERIC;

	DMSG("Saving key pair");
	res = serialize_key(buf, size);
	if (res)
		return res;

	res = sec_storage_obj_write(&pta_uuid, TEE_STORAGE_PRIVATE,
				    key_file_name, sizeof(key_file_name) - 1,
				    buf, size, 0, TEE_DATA_FLAG_ACCESS_WRITE);
	if (!res)
		DMSG("Wrote %zu bytes", size);
	return res;
}

static TEE_Result init_key(void)
{
	TEE_Result res = TEE_SUCCESS;
	uint8_t *buf = NULL;
	size_t size = 0;

	if (!key) {
		/*
		 * e is 65537 so its bignum size is 3 bytes. d and n can be up
		 * to MAX_KEY_SIZE bits.
		 */
		size = bufsize(3, MAX_KEY_SIZE / 8, MAX_KEY_SIZE / 8);
		buf = calloc(1, size);
		if (!buf) {
			res = TEE_ERROR_OUT_OF_MEMORY;
			goto out;
		}
		res = load_key(buf, size);
		if (res == TEE_ERROR_ITEM_NOT_FOUND) {
			res = generate_key();
			if (res)
				goto out;
			res = write_key(buf, size);
		}
	}
out:
	free(buf);
	return res;
}

static TEE_Result cmd_get_pubkey(uint32_t param_types,
				 TEE_Param params[TEE_NUM_PARAMS])
{
	TEE_Result res = TEE_ERROR_GENERIC;
	uint8_t *e = params[0].memref.buffer;
	size_t *e_out_sz = &params[0].memref.size;
	uint8_t *n = params[1].memref.buffer;
	size_t *n_out_sz = &params[1].memref.size;
	size_t sz = 0;

	if (param_types != TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_OUTPUT,
					   TEE_PARAM_TYPE_MEMREF_OUTPUT,
					   TEE_PARAM_TYPE_VALUE_OUTPUT,
					   TEE_PARAM_TYPE_NONE))
		return TEE_ERROR_BAD_PARAMETERS;

	res = init_key();
	if (res)
		return res;

	sz = crypto_bignum_num_bytes(key->e);
	if (*e_out_sz >= sz)
		crypto_bignum_bn2bin(key->e, e);
	else
		res = TEE_ERROR_SHORT_BUFFER;
	*e_out_sz = sz;

	sz = crypto_bignum_num_bytes(key->n);
	if (*n_out_sz >= sz)
		crypto_bignum_bn2bin(key->n, n);
	else
		res = TEE_ERROR_SHORT_BUFFER;
	*n_out_sz = sz;

	params[2].value.a = TEE_ALG_RSASSA_PKCS1_PSS_MGF1_SHA256;

	return res;
}

static TEE_Result hash_binary(const TEE_UUID *uuid, uint8_t *hash)
{
	TEE_Result res = TEE_ERROR_ITEM_NOT_FOUND;
	unsigned int tag_len = FILE_TAG_SIZE;
	const struct ts_store_ops *ops = NULL;
	struct ts_store_handle *h = NULL;

	SCATTERED_ARRAY_FOREACH(ops, ta_stores, struct ts_store_ops) {
		res = ops->open(uuid, &h);
		if (!res)
			break;  /* TA found */
	}
	if (res)
		return res;

	/*
	 * Output hash size is assumed to be the same size as the file tag
	 * size which is the size of the digest in the TA shdr. If one or the
	 * other changes, additional hashing will be needed.
	 */
	COMPILE_TIME_ASSERT(FILE_TAG_SIZE == TEE_SHA256_HASH_SIZE);
	assert(ops);
	res = ops->get_tag(h, hash, &tag_len);
	if (res)
		goto out;

	DMSG("TA %pUl hash:", uuid);
	DHEXDUMP(hash, TEE_SHA256_HASH_SIZE);
out:
	ops->close(h);
	return res;
}

/* Hash @nonce and @hash into @digest */
static TEE_Result digest_nonce_and_hash(uint8_t *digest, uint8_t *nonce,
					size_t nonce_sz, uint8_t *hash)
{
	TEE_Result res = TEE_SUCCESS;
	void *ctx = NULL;

	res = crypto_hash_alloc_ctx(&ctx, TEE_ALG_SHA256);
	if (res)
		return res;
	res = crypto_hash_init(ctx);
	if (res)
		goto out;
	res = crypto_hash_update(ctx, nonce, nonce_sz);
	if (res)
		goto out;
	res = crypto_hash_update(ctx, hash, TEE_SHA256_HASH_SIZE);
	if (res)
		goto out;
	res = crypto_hash_final(ctx, digest, TEE_SHA256_HASH_SIZE);
out:
	crypto_hash_free_ctx(ctx);
	return res;
}

static TEE_Result sign_digest(uint8_t *sig, size_t sig_len,
			      const uint8_t *digest)
{
	return crypto_acipher_rsassa_sign(TEE_ALG_RSASSA_PKCS1_PSS_MGF1_SHA256,
					  key,
					  TEE_SHA256_HASH_SIZE, /* salt len */
					  digest, TEE_SHA256_HASH_SIZE,
					  sig, &sig_len);
}

/*
 * Sign the first 32 bytes contained in @buf and append signature
 * out = [ hash | sig(sha256(nonce | hash)) ]
 *         ^^^^   ^^^^^^^^^^^^^^^^^^^^^^^^^
 *          32B                modulus size
 */
static TEE_Result sign_buffer(uint8_t *buf, size_t buf_sz, uint8_t *nonce,
			      size_t nonce_sz)
{
	uint8_t digest[TEE_SHA256_HASH_SIZE] = { };
	TEE_Result res = TEE_SUCCESS;

	res = digest_nonce_and_hash(digest, nonce, nonce_sz, buf);
	if (res)
		return res;
	return sign_digest(buf + TEE_SHA256_HASH_SIZE,
			   buf_sz - TEE_SHA256_HASH_SIZE, digest);
}

/*
 * Is region valid for hashing?
 * Exclude writable regions as well as those that are not specific to the TA
 * (ldelf, kernel or temporary mappings).
 */
static bool is_region_valid(struct vm_region *r)
{
	uint32_t dontwant = VM_FLAG_EPHEMERAL | VM_FLAG_PERMANENT |
			    VM_FLAG_LDELF;
	uint32_t want = VM_FLAG_READONLY;

	return ((r->flags & want) == want && !(r->flags & dontwant));
}

/*
 * With this comparison function, we're hashing the smaller regions first.
 * Regions of equal size are ordered based on their content (memcmp()).
 * Identical regions can be in any order since they will yield the same hash
 * anyways.
 */
static int cmp_regions(const void *a, const void *b)
{
	const struct vm_region *r1 = *(const struct vm_region **)a;
	const struct vm_region *r2 = *(const struct vm_region **)b;

	if (r1->size < r2->size)
		return -1;

	if (r1->size > r2->size)
		return 1;

	return memcmp((void *)r1->va, (void *)r2->va, r1->size);
}

static TEE_Result hash_regions(struct vm_info *vm_info, uint8_t *hash)
{
	TEE_Result res = TEE_SUCCESS;
	struct vm_region *r = NULL;
	struct vm_region **regions = NULL;
	size_t nregions = 0;
	void *ctx = NULL;
	size_t i = 0;

	res = crypto_hash_alloc_ctx(&ctx, TEE_ALG_SHA256);
	if (res)
		return res;

	res = crypto_hash_init(ctx);
	if (res)
		goto out;

	/*
	 * Make an array of region pointers so we can use qsort() to order it.
	 */

	TAILQ_FOREACH(r, &vm_info->regions, link)
		if (is_region_valid(r))
			nregions++;

	regions = malloc(nregions * sizeof(*regions));
	if (!regions) {
		res = TEE_ERROR_OUT_OF_MEMORY;
		goto out;
	}

	TAILQ_FOREACH(r, &vm_info->regions, link)
		if (is_region_valid(r))
			regions[i++] = r;

	enter_user_access();

	/*
	 * Sort regions so that they are in a consistent order even when TA ASLR
	 * is enabled.
	 */
	qsort(regions, nregions, sizeof(*regions), cmp_regions);

	/* Hash regions in order */
	for (i = 0; i < nregions; i++) {
		r = regions[i];
		DMSG("va %p size %zu", (void *)r->va, r->size);
		res = crypto_hash_update(ctx, (uint8_t *)r->va, r->size);
		if (res)
			break;
	}

	exit_user_access();

	if (res)
		goto out;

	res = crypto_hash_final(ctx, hash, TEE_SHA256_HASH_SIZE);
out:
	free(regions);
	crypto_hash_free_ctx(ctx);
	return res;
}

static TEE_Result cmd_get_ta_shdr_digest(uint32_t param_types,
					 TEE_Param params[TEE_NUM_PARAMS])
{
	TEE_UUID *uuid = params[0].memref.buffer;
	size_t uuid_sz = params[0].memref.size;
	uint8_t *nonce = params[1].memref.buffer;
	size_t nonce_sz = params[1].memref.size;
	uint8_t *out = params[2].memref.buffer;
	size_t out_sz = params[2].memref.size;
	size_t min_out_sz = 0;
	TEE_Result res = TEE_SUCCESS;

	if (param_types != TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_INPUT,
					   TEE_PARAM_TYPE_MEMREF_INPUT,
					   TEE_PARAM_TYPE_MEMREF_OUTPUT,
					   TEE_PARAM_TYPE_NONE))
		return TEE_ERROR_BAD_PARAMETERS;

	if (uuid_sz != sizeof(*uuid))
		return TEE_ERROR_BAD_PARAMETERS;

	if (!nonce || !nonce_sz)
		return TEE_ERROR_BAD_PARAMETERS;

	if (!out && out_sz)
		return TEE_ERROR_BAD_PARAMETERS;

	res = init_key();
	if (res)
		return res;

	min_out_sz = TEE_SHA256_HASH_SIZE + crypto_bignum_num_bytes(key->n);
	params[2].memref.size = min_out_sz;
	if (out_sz < min_out_sz)
		return TEE_ERROR_SHORT_BUFFER;
	out_sz = min_out_sz;

	res = hash_binary(uuid, out);
	if (res)
		return res;
	return sign_buffer(out, out_sz, nonce, nonce_sz);
}

static TEE_Result cmd_hash_ta_memory(uint32_t param_types,
				     TEE_Param params[TEE_NUM_PARAMS])
{
	uint8_t *nonce = params[0].memref.buffer;
	size_t nonce_sz = params[0].memref.size;
	uint8_t *out = params[1].memref.buffer;
	size_t out_sz = params[1].memref.size;
	struct user_mode_ctx *uctx = NULL;
	TEE_Result res = TEE_SUCCESS;
	struct ts_session *s = NULL;
	size_t min_out_sz = 0;

	if (param_types != TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_INPUT,
					   TEE_PARAM_TYPE_MEMREF_OUTPUT,
					   TEE_PARAM_TYPE_NONE,
					   TEE_PARAM_TYPE_NONE))
		return TEE_ERROR_BAD_PARAMETERS;

	if (!nonce || !nonce_sz)
		return TEE_ERROR_BAD_PARAMETERS;

	if (!out && out_sz)
		return TEE_ERROR_BAD_PARAMETERS;

	/* Check that we're called from a user TA */
	s = ts_get_calling_session();
	if (!s)
		return TEE_ERROR_ACCESS_DENIED;
	uctx = to_user_mode_ctx(s->ctx);
	if (!uctx)
		return TEE_ERROR_ACCESS_DENIED;

	res = init_key();
	if (res)
		return res;

	min_out_sz = TEE_SHA256_HASH_SIZE + crypto_bignum_num_bytes(key->n);
	params[1].memref.size = min_out_sz;
	if (out_sz < min_out_sz)
		return TEE_ERROR_SHORT_BUFFER;
	out_sz = min_out_sz;

	s = ts_pop_current_session();
	res = hash_regions(&uctx->vm_info, out);
	ts_push_current_session(s);
	if (res)
		return res;

	return sign_buffer(out, out_sz, nonce, nonce_sz);
}

static TEE_Result cmd_hash_tee_memory(uint32_t param_types,
				      TEE_Param params[TEE_NUM_PARAMS])
{
	uint8_t *nonce = params[0].memref.buffer;
	size_t nonce_sz = params[0].memref.size;
	uint8_t *out = params[1].memref.buffer;
	size_t out_sz = params[1].memref.size;
	TEE_Result res = TEE_SUCCESS;
	size_t min_out_sz = 0;
	void *ctx = NULL;

	if (param_types != TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_INPUT,
					   TEE_PARAM_TYPE_MEMREF_OUTPUT,
					   TEE_PARAM_TYPE_NONE,
					   TEE_PARAM_TYPE_NONE))
		return TEE_ERROR_BAD_PARAMETERS;

	if (!nonce || !nonce_sz)
		return TEE_ERROR_BAD_PARAMETERS;

	if (!out && out_sz)
		return TEE_ERROR_BAD_PARAMETERS;

	res = init_key();
	if (res)
		return res;

	min_out_sz = TEE_SHA256_HASH_SIZE + crypto_bignum_num_bytes(key->n);
	params[1].memref.size = min_out_sz;
	if (out_sz < min_out_sz)
		return TEE_ERROR_SHORT_BUFFER;
	out_sz = min_out_sz;

	res = crypto_hash_alloc_ctx(&ctx, TEE_ALG_SHA256);
	if (res)
		return res;
	res = crypto_hash_init(ctx);
	if (res)
		goto out;
	res = crypto_hash_update(ctx, __text_start,
				 __text_data_start - __text_start);
	if (res)
		goto out;
	res = crypto_hash_update(ctx, __text_data_end,
				 __text_end - __text_data_end);
	if (IS_ENABLED(CFG_WITH_PAGER)) {
		res = crypto_hash_update(ctx, __text_init_start,
					 __text_init_end - __text_init_start);
		if (res)
			goto out;
		res = crypto_hash_update(ctx, __text_pageable_start,
					 __text_pageable_end -
						__text_pageable_start);
		if (res)
			goto out;
	}
	if (res)
		goto out;
	res = crypto_hash_update(ctx, __rodata_start,
				 __rodata_end - __rodata_start);
	if (res)
		goto out;
	if (IS_ENABLED(CFG_WITH_PAGER)) {
		res = crypto_hash_update(ctx, __rodata_init_start,
					 __rodata_init_end -
						__rodata_init_start);
		if (res)
			goto out;
		res = crypto_hash_update(ctx, __rodata_pageable_start,
					 __rodata_pageable_end -
						__rodata_pageable_start);
		if (res)
			goto out;
	}
	res = crypto_hash_final(ctx, out, TEE_SHA256_HASH_SIZE);
	if (res)
		goto out;

	DHEXDUMP(out, TEE_SHA256_HASH_SIZE);

	res = sign_buffer(out, out_sz, nonce, nonce_sz);
out:
	crypto_hash_free_ctx(ctx);
	return res;
}

static TEE_Result invoke_command(void *sess_ctx __unused, uint32_t cmd_id,
				 uint32_t param_types,
				 TEE_Param params[TEE_NUM_PARAMS])
{
	TEE_Result res = TEE_ERROR_BAD_PARAMETERS;
	TEE_Result res2 = TEE_ERROR_GENERIC;
	TEE_Param bparams[TEE_NUM_PARAMS] = { };
	TEE_Param *eparams = NULL;

	res = to_bounce_params(param_types, params, bparams, &eparams);
	if (res)
		return res;

	switch (cmd_id) {
	case PTA_ATTESTATION_GET_PUBKEY:
		res = cmd_get_pubkey(param_types, eparams);
		break;
	case PTA_ATTESTATION_GET_TA_SHDR_DIGEST:
		res = cmd_get_ta_shdr_digest(param_types, eparams);
		break;
	case PTA_ATTESTATION_HASH_TA_MEMORY:
		res = cmd_hash_ta_memory(param_types, eparams);
		break;
	case PTA_ATTESTATION_HASH_TEE_MEMORY:
		res = cmd_hash_tee_memory(param_types, eparams);
		break;
	default:
		break;
	}

	res2 = from_bounce_params(param_types, params, bparams, eparams);
	if (!res && res2)
		res = res2;

	return res;
}

pseudo_ta_register(.uuid = PTA_ATTESTATION_UUID, .name = PTA_NAME,
		   .flags = PTA_DEFAULT_FLAGS,
		   .invoke_command_entry_point = invoke_command);