101 lines
2.5 KiB
C
101 lines
2.5 KiB
C
/*
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* Copyright (c) 2018 Oticon A/S
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Pseudo-random entropy generator for the ARCH_POSIX architecture:
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* Following the principle of reproducibility of the native_posix board
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* this entropy device will always generate the same random sequence when
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* initialized with the same seed
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*
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* This entropy source should only be used for testing.
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*/
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#include "device.h"
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#include "entropy.h"
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#include "init.h"
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#include "misc/util.h"
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#include <stdlib.h>
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#include <string.h>
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#include "posix_trace.h"
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#include "soc.h"
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#include "cmdline.h" /* native_posix command line options header */
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static unsigned int seed = 0x5678;
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static int entropy_native_posix_get_entropy(struct device *dev, u8_t *buffer,
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u16_t length)
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{
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ARG_UNUSED(dev);
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while (length) {
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/*
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* Note that only 1 thread (Zephyr thread or HW models), runs at
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* a time, therefore there is no need to use random_r()
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*/
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long int value = random();
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size_t to_copy = MIN(length, sizeof(long int));
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memcpy(buffer, &value, to_copy);
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buffer += to_copy;
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length -= to_copy;
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}
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return 0;
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}
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static int entropy_native_posix_get_entropy_isr(struct device *dev, u8_t *buf,
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u16_t len, u32_t flags)
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{
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ARG_UNUSED(flags);
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/*
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* entropy_native_posix_get_entropy() is also safe for ISRs
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* and always produces data.
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*/
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return entropy_native_posix_get_entropy(dev, buf, len);
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}
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static int entropy_native_posix_init(struct device *dev)
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{
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ARG_UNUSED(dev);
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srandom(seed);
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posix_print_warning("WARNING: "
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"Using a test - not safe - entropy source\n");
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return 0;
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}
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static const struct entropy_driver_api entropy_native_posix_api_funcs = {
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.get_entropy = entropy_native_posix_get_entropy,
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.get_entropy_isr = entropy_native_posix_get_entropy_isr
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};
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DEVICE_AND_API_INIT(entropy_native_posix, CONFIG_ENTROPY_NAME,
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entropy_native_posix_init, NULL, NULL,
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PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
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&entropy_native_posix_api_funcs);
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static void add_fake_entropy_option(void)
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{
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static struct args_struct_t entropy_options[] = {
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/*
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* Fields:
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* manual, mandatory, switch,
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* option_name, var_name ,type,
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* destination, callback,
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* description
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*/
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{false, false, false,
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"seed", "r_seed", 'u',
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(void *)&seed, NULL,
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"A 32-bit integer seed value for the entropy device, such as "
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"97229 (decimal), 0x17BCD (hex), or 0275715 (octal)"},
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ARG_TABLE_ENDMARKER
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};
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native_add_command_line_opts(entropy_options);
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}
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NATIVE_TASK(add_fake_entropy_option, PRE_BOOT_1, 10);
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