xref: /optee_os/lib/libmbedtls/core/aes_ctr.c (revision 9c525fe4cdfe48d2394afe8440a56e7db36cc91f)

// SPDX-License-Identifier: BSD-2-Clause
/*
 * Copyright (C) 2019, Linaro Limited
 * Copyright (C) 2021, Huawei Technologies Co., Ltd
 */

#include <assert.h>
#include <compiler.h>
#include <crypto/crypto_accel.h>
#include <crypto/crypto.h>
#include <crypto/crypto_impl.h>
#include <mbedtls/aes.h>
#include <stdlib.h>
#include <string.h>
#include <tee_api_types.h>
#include <utee_defines.h>
#include <util.h>

#include "mbed_helpers.h"

struct mbed_aes_ctr_ctx {
	struct crypto_cipher_ctx ctx;
	mbedtls_aes_context aes_ctx;
	size_t nc_off;
	unsigned char counter[TEE_AES_BLOCK_SIZE];
	unsigned char block[TEE_AES_BLOCK_SIZE];
};

static const struct crypto_cipher_ops mbed_aes_ctr_ops;

static struct mbed_aes_ctr_ctx *to_aes_ctr_ctx(struct crypto_cipher_ctx *ctx)
{
	assert(ctx && ctx->ops == &mbed_aes_ctr_ops);

	return container_of(ctx, struct mbed_aes_ctr_ctx, ctx);
}

static TEE_Result mbed_aes_ctr_init(struct crypto_cipher_ctx *ctx,
				    TEE_OperationMode mode __unused,
				    const uint8_t *key1, size_t key1_len,
				    const uint8_t *key2 __unused,
				    size_t key2_len __unused,
				    const uint8_t *iv, size_t iv_len)
{
	struct mbed_aes_ctr_ctx *c = to_aes_ctr_ctx(ctx);

	if (iv_len != sizeof(c->counter))
		return TEE_ERROR_BAD_PARAMETERS;
	memcpy(c->counter, iv, sizeof(c->counter));

	mbedtls_aes_init(&c->aes_ctx);
	c->nc_off = 0;

	if (mbedtls_aes_setkey_enc(&c->aes_ctx, key1, key1_len * 8))
		return TEE_ERROR_BAD_STATE;

	return TEE_SUCCESS;
}

static TEE_Result mbed_aes_ctr_update(struct crypto_cipher_ctx *ctx,
				      bool last_block __unused,
				      const uint8_t *data, size_t len,
				      uint8_t *dst)
{
	struct mbed_aes_ctr_ctx *c = to_aes_ctr_ctx(ctx);

	if (mbedtls_aes_crypt_ctr(&c->aes_ctx, len, &c->nc_off, c->counter,
				   c->block, data, dst))
		return TEE_ERROR_BAD_STATE;

	return TEE_SUCCESS;
}

static void mbed_aes_ctr_final(struct crypto_cipher_ctx *ctx)
{
	struct mbed_aes_ctr_ctx *c = to_aes_ctr_ctx(ctx);

	mbedtls_aes_free(&c->aes_ctx);
	memset(c->block, 0, sizeof(c->block));
}

static void mbed_aes_ctr_free_ctx(struct crypto_cipher_ctx *ctx)
{
	free(to_aes_ctr_ctx(ctx));
}

static void mbed_aes_ctr_copy_state(struct crypto_cipher_ctx *dst_ctx,
				    struct crypto_cipher_ctx *src_ctx)
{
	struct mbed_aes_ctr_ctx *src = to_aes_ctr_ctx(src_ctx);
	struct mbed_aes_ctr_ctx *dst = to_aes_ctr_ctx(dst_ctx);

	memcpy(dst->counter, src->counter, sizeof(dst->counter));
	memcpy(dst->block, src->block, sizeof(dst->block));
	dst->nc_off = src->nc_off;
	mbed_copy_mbedtls_aes_context(&dst->aes_ctx, &src->aes_ctx);
}

static const struct crypto_cipher_ops mbed_aes_ctr_ops = {
	.init = mbed_aes_ctr_init,
	.update = mbed_aes_ctr_update,
	.final = mbed_aes_ctr_final,
	.free_ctx = mbed_aes_ctr_free_ctx,
	.copy_state = mbed_aes_ctr_copy_state,
};

TEE_Result crypto_aes_ctr_alloc_ctx(struct crypto_cipher_ctx **ctx_ret)
{
	struct mbed_aes_ctr_ctx *c = NULL;

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

	c->ctx.ops = &mbed_aes_ctr_ops;
	*ctx_ret = &c->ctx;

	return TEE_SUCCESS;
}

#if defined(MBEDTLS_AES_ALT)
static void next_ctr(unsigned char stream_block[16], mbedtls_aes_context *ctx,
		     unsigned char nonce_counter[16])
{
	const unsigned char zeroes[16] = { 0 };

	crypto_accel_aes_ctr_be_enc(stream_block, zeroes, ctx->key,
				    ctx->round_count, 1, nonce_counter);
}

int mbedtls_aes_crypt_ctr(mbedtls_aes_context *ctx, size_t length,
			  size_t *nc_off, unsigned char nonce_counter[16],
			  unsigned char stream_block[16],
			  const unsigned char *input, unsigned char *output)
{
	size_t offs = 0;

	if (*nc_off >= 16)
		return MBEDTLS_ERR_AES_BAD_INPUT_DATA;

	/*
	 * If the stream_block is in use, continue until done or
	 * stream_block is consumed.
	 */
	while (*nc_off) {
		output[offs] = stream_block[*nc_off] ^ input[offs];
		offs++;
		*nc_off = (*nc_off + 1) % 16;
		if (offs == length)
			return 0;
	}

	if ((length - offs) >= 16) {
		size_t block_count = (length - offs) / 16;

		crypto_accel_aes_ctr_be_enc(output + offs, input + offs,
					    ctx->key, ctx->round_count,
					    block_count, nonce_counter);
		offs += block_count * 16;
	}

	while (offs < length) {
		if (!*nc_off)
			next_ctr(stream_block, ctx, nonce_counter);
		output[offs] = stream_block[*nc_off] ^ input[offs];
		offs++;
		*nc_off = (*nc_off + 1) % 16;
	}

	return 0;
}
#endif /*MBEDTLS_AES_ALT*/