rdrand_sanitytest.c
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/*
* Copyright 2018 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "testutil.h"
#include <openssl/opensslconf.h>
#if (defined(__i386) || defined(__i386__) || defined(_M_IX86) || \
defined(__x86_64) || defined(__x86_64__) || \
defined(_M_AMD64) || defined (_M_X64)) && defined(OPENSSL_CPUID_OBJ)
size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf, size_t len);
size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf, size_t len);
void OPENSSL_cpuid_setup(void);
extern unsigned int OPENSSL_ia32cap_P[4];
static int sanity_check_bytes(size_t (*rng)(unsigned char *, size_t),
int rounds, int min_failures, int max_retries, int max_zero_words)
{
int testresult = 0;
unsigned char prior[31] = {0}, buf[31] = {0}, check[7];
int failures = 0, zero_words = 0;
int i;
for (i = 0; i < rounds; i++) {
size_t generated = 0;
int retry;
for (retry = 0; retry < max_retries; retry++) {
generated = rng(buf, sizeof(buf));
if (generated == sizeof(buf))
break;
failures++;
}
/*-
* Verify that we don't have too many unexpected runs of zeroes,
* implying that we might be accidentally using the 32-bit RDRAND
* instead of the 64-bit one on 64-bit systems.
*/
size_t j;
for (j = 0; j < sizeof(buf) - 1; j++) {
if (buf[j] == 0 && buf[j+1] == 0) {
zero_words++;
}
}
if (!TEST_int_eq(generated, sizeof(buf)))
goto end;
if (!TEST_false(!memcmp(prior, buf, sizeof(buf))))
goto end;
/* Verify that the last 7 bytes of buf aren't all the same value */
unsigned char *tail = &buf[sizeof(buf) - sizeof(check)];
memset(check, tail[0], 7);
if (!TEST_false(!memcmp(check, tail, sizeof(check))))
goto end;
/* Save the result and make sure it's different next time */
memcpy(prior, buf, sizeof(buf));
}
if (!TEST_int_le(zero_words, max_zero_words))
goto end;
if (!TEST_int_ge(failures, min_failures))
goto end;
testresult = 1;
end:
return testresult;
}
static int sanity_check_rdrand_bytes(void)
{
return sanity_check_bytes(OPENSSL_ia32_rdrand_bytes, 1000, 0, 10, 10);
}
static int sanity_check_rdseed_bytes(void)
{
/*-
* RDSEED may take many retries to succeed; note that this is effectively
* multiplied by the 8x retry loop in asm, and failure probabilities are
* increased by the fact that we need either 4 or 8 samples depending on
* the platform.
*/
return sanity_check_bytes(OPENSSL_ia32_rdseed_bytes, 1000, 1, 10000, 10);
}
int setup_tests(void)
{
OPENSSL_cpuid_setup();
int have_rdseed = (OPENSSL_ia32cap_P[2] & (1 << 18)) != 0;
int have_rdrand = (OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0;
if (have_rdrand) {
ADD_TEST(sanity_check_rdrand_bytes);
}
if (have_rdseed) {
ADD_TEST(sanity_check_rdseed_bytes);
}
return 1;
}
#else
int setup_tests(void)
{
return 1;
}
#endif