81 lines
1.8 KiB
C
81 lines
1.8 KiB
C
/*
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* Copyright (c) 2017 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/sys/atomic.h>
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#include <zephyr/kernel.h>
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#include <zephyr/drivers/entropy.h>
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#include <string.h>
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static const struct device *const entropy_dev =
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DEVICE_DT_GET(DT_CHOSEN(zephyr_entropy));
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static int rand_get(uint8_t *dst, size_t outlen, bool csrand)
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{
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uint32_t random_num;
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int ret;
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__ASSERT(device_is_ready(entropy_dev), "Entropy device %s not ready",
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entropy_dev->name);
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ret = entropy_get_entropy(entropy_dev, dst, outlen);
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if (unlikely(ret < 0)) {
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/* Don't try to fill the buffer in case of
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* cryptographically secure random numbers, just
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* propagate the driver error.
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*/
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if (csrand) {
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return ret;
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}
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/* Use system timer in case the entropy device couldn't deliver
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* 32-bit of data. There's not much that can be done in this
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* situation. An __ASSERT() isn't used here as the HWRNG might
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* still be gathering entropy during early boot situations.
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*/
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uint32_t len = 0;
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uint32_t blocksize = 4;
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while (len < outlen) {
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size_t copylen = outlen - len;
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if (copylen > blocksize) {
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copylen = blocksize;
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}
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random_num = k_cycle_get_32();
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(void)memcpy(&(dst[len]), &random_num, copylen);
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len += copylen;
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}
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}
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return 0;
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}
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#if defined(CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR)
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void z_impl_sys_rand_get(void *dst, size_t outlen)
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{
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rand_get(dst, outlen, false);
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}
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#endif /* CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR */
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#if defined(CONFIG_HARDWARE_DEVICE_CS_GENERATOR)
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int z_impl_sys_csrand_get(void *dst, size_t outlen)
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{
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if (rand_get(dst, outlen, true) != 0) {
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/* Is it the only error it should return ? entropy_sam
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* can return -ETIMEDOUT for example
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*/
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return -EIO;
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}
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return 0;
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}
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#endif /* CONFIG_HARDWARE_DEVICE_CS_GENERATOR */
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