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/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#define BR_ENABLE_INTRINSICS 1
#include "inner.h"
#if BR_USE_URANDOM
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#endif
#if BR_USE_WIN32_RAND
#include <windows.h>
#include <wincrypt.h>
#pragma comment(lib, "advapi32")
#endif
#if BR_RDRAND
BR_TARGETS_X86_UP
BR_TARGET("rdrnd")
static int
seeder_rdrand(const br_prng_class **ctx)
{
unsigned char tmp[32];
size_t u;
for (u = 0; u < sizeof tmp; u += sizeof(uint32_t)) {
int j;
uint32_t x;
/*
* We use the 32-bit intrinsic so that code is compatible
* with both 32-bit and 64-bit architectures.
*
* Intel recommends trying at least 10 times in case of
* failure.
*/
for (j = 0; j < 10; j ++) {
if (_rdrand32_step(&x)) {
goto next_word;
}
}
return 0;
next_word:
br_enc32le(tmp + u, x);
}
(*ctx)->update(ctx, tmp, sizeof tmp);
return 1;
}
BR_TARGETS_X86_DOWN
static int
rdrand_supported(void)
{
/*
* The RDRND support is bit 30 of ECX, as returned by CPUID.
*/
return br_cpuid(0, 0, 0x40000000, 0);
}
#endif
#if BR_USE_URANDOM
static int
seeder_urandom(const br_prng_class **ctx)
{
int f;
f = open("/dev/urandom", O_RDONLY);
if (f >= 0) {
unsigned char tmp[32];
size_t u;
for (u = 0; u < sizeof tmp;) {
ssize_t len;
len = read(f, tmp + u, (sizeof tmp) - u);
if (len < 0) {
if (errno == EINTR) {
continue;
}
break;
}
u += (size_t)len;
}
close(f);
if (u == sizeof tmp) {
(*ctx)->update(ctx, tmp, sizeof tmp);
return 1;
}
}
return 0;
}
#endif
#if BR_USE_WIN32_RAND
static int
seeder_win32(const br_prng_class **ctx)
{
HCRYPTPROV hp;
if (CryptAcquireContext(&hp, 0, 0, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
{
BYTE buf[32];
BOOL r;
r = CryptGenRandom(hp, sizeof buf, buf);
CryptReleaseContext(hp, 0);
if (r) {
(*ctx)->update(ctx, buf, sizeof buf);
return 1;
}
}
return 0;
}
#endif
/* see bearssl_rand.h */
br_prng_seeder
br_prng_seeder_system(const char **name)
{
#if BR_RDRAND
if (rdrand_supported()) {
if (name != NULL) {
*name = "rdrand";
}
return &seeder_rdrand;
}
#endif
#if BR_USE_URANDOM
if (name != NULL) {
*name = "urandom";
}
return &seeder_urandom;
#elif BR_USE_WIN32_RAND
if (name != NULL) {
*name = "win32";
}
return &seeder_win32;
#else
if (name != NULL) {
*name = "none";
}
return 0;
#endif
}
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