160 lines
3.1 KiB
C
160 lines
3.1 KiB
C
/*
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* Copyright (c) 2019, NXP
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/init.h>
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#include <zephyr/device.h>
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#include <zephyr/drivers/entropy.h>
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#include <zephyr/kernel.h>
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#include <string.h>
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#if defined(CONFIG_MBEDTLS)
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#if !defined(CONFIG_MBEDTLS_CFG_FILE)
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#include "mbedtls/config.h"
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#else
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#include CONFIG_MBEDTLS_CFG_FILE
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#endif /* CONFIG_MBEDTLS_CFG_FILE */
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#include <mbedtls/ctr_drbg.h>
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#elif defined(CONFIG_TINYCRYPT)
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#include <tinycrypt/ctr_prng.h>
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#include <tinycrypt/aes.h>
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#include <tinycrypt/constants.h>
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#endif /* CONFIG_MBEDTLS */
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/*
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* entropy_dev is initialized at runtime to allow first time initialization
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* of the ctr_drbg engine.
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*/
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static const struct device *entropy_dev;
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static const unsigned char drbg_seed[] = CONFIG_CS_CTR_DRBG_PERSONALIZATION;
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static bool ctr_initialised;
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static struct k_mutex ctr_lock;
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#if defined(CONFIG_MBEDTLS)
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static mbedtls_ctr_drbg_context ctr_ctx;
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static int ctr_drbg_entropy_func(void *ctx, unsigned char *buf, size_t len)
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{
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return entropy_get_entropy(entropy_dev, (void *)buf, len);
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}
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#elif defined(CONFIG_TINYCRYPT)
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static TCCtrPrng_t ctr_ctx;
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#endif /* CONFIG_MBEDTLS */
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static int ctr_drbg_initialize(void)
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{
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int ret;
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entropy_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_entropy));
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if (!device_is_ready(entropy_dev)) {
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__ASSERT(0, "Entropy device %s not ready", entropy_dev->name);
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return -ENODEV;
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}
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#if defined(CONFIG_MBEDTLS)
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mbedtls_ctr_drbg_init(&ctr_ctx);
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ret = mbedtls_ctr_drbg_seed(&ctr_ctx,
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ctr_drbg_entropy_func,
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NULL,
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drbg_seed,
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sizeof(drbg_seed));
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if (ret != 0) {
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mbedtls_ctr_drbg_free(&ctr_ctx);
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return -EIO;
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}
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#elif defined(CONFIG_TINYCRYPT)
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uint8_t entropy[TC_AES_KEY_SIZE + TC_AES_BLOCK_SIZE];
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ret = entropy_get_entropy(entropy_dev, (void *)&entropy,
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sizeof(entropy));
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if (ret != 0) {
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return -EIO;
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}
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ret = tc_ctr_prng_init(&ctr_ctx,
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(uint8_t *)&entropy,
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sizeof(entropy),
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(uint8_t *)drbg_seed,
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sizeof(drbg_seed));
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if (ret == TC_CRYPTO_FAIL) {
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return -EIO;
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}
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#endif
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ctr_initialised = true;
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return 0;
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}
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int z_impl_sys_csrand_get(void *dst, uint32_t outlen)
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{
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int ret;
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k_mutex_lock(&ctr_lock, K_FOREVER);
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if (unlikely(!ctr_initialised)) {
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ret = ctr_drbg_initialize();
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if (ret != 0) {
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ret = -EIO;
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goto end;
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}
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}
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#if defined(CONFIG_MBEDTLS)
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ret = mbedtls_ctr_drbg_random(&ctr_ctx, (unsigned char *)dst, outlen);
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#elif defined(CONFIG_TINYCRYPT)
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uint8_t entropy[TC_AES_KEY_SIZE + TC_AES_BLOCK_SIZE];
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ret = tc_ctr_prng_generate(&ctr_ctx, 0, 0, (uint8_t *)dst, outlen);
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if (ret == TC_CRYPTO_SUCCESS) {
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ret = 0;
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} else if (ret == TC_CTR_PRNG_RESEED_REQ) {
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ret = entropy_get_entropy(entropy_dev,
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(void *)&entropy, sizeof(entropy));
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if (ret != 0) {
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ret = -EIO;
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goto end;
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}
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ret = tc_ctr_prng_reseed(&ctr_ctx,
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entropy,
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sizeof(entropy),
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drbg_seed,
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sizeof(drbg_seed));
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ret = tc_ctr_prng_generate(&ctr_ctx, 0, 0,
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(uint8_t *)dst, outlen);
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ret = (ret == TC_CRYPTO_SUCCESS) ? 0 : -EIO;
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} else {
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ret = -EIO;
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}
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#endif
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end:
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k_mutex_unlock(&ctr_lock);
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return ret;
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}
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