6216c6cf5b
Create syscalls to make possible using random APIs from user mode threads. These APIs can have different implementations, like using entropy driver or Xoroshiro128. Some of these implementations also have some globals to preserve state between calls. Make it run entire in user space would require user adding these globals to their memeory domains and/or grant access to entropy device. Syscalls simplify its usage. Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
153 lines
3 KiB
C
153 lines
3 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 <init.h>
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#include <device.h>
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#include <drivers/entropy.h>
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#include <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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static K_SEM_DEFINE(state_sem, 1, 1);
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static struct device *entropy_driver;
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static const unsigned char drbg_seed[] = CONFIG_CS_CTR_DRBG_PERSONALIZATION;
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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(ctx, (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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/* Only one entropy device exists, so this is safe even
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* if the whole operation isn't atomic.
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*/
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entropy_driver = device_get_binding(DT_CHOSEN_ZEPHYR_ENTROPY_LABEL);
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if (!entropy_driver) {
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__ASSERT((entropy_driver != NULL),
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"Device driver for %s (DT_CHOSEN_ZEPHYR_ENTROPY_LABEL) not found. "
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"Check your build configuration!",
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DT_CHOSEN_ZEPHYR_ENTROPY_LABEL);
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return -EINVAL;
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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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entropy_driver,
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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_driver, (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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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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unsigned int key = irq_lock();
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if (unlikely(!entropy_driver)) {
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ret = ctr_drbg_initialize();
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if (ret != 0) {
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return ret;
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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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entropy_get_entropy(entropy_driver,
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(void *)&entropy, sizeof(entropy));
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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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irq_unlock(key);
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return ret;
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}
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