monero/src/crypto/random.c
moneromooo-monero d539be3359
crypto: make clear generate_random_bytes is not thread safe
And add a thread safe version to encourage proper use
2016-05-15 00:05:59 +01:00

144 lines
4.1 KiB
C

// Copyright (c) 2014-2016, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
#include <assert.h>
#include <stddef.h>
#include <string.h>
#include "hash-ops.h"
#include "initializer.h"
#include "random.h"
static void generate_system_random_bytes(size_t n, void *result);
#if defined(_WIN32)
#include <windows.h>
#include <wincrypt.h>
static void generate_system_random_bytes(size_t n, void *result) {
HCRYPTPROV prov;
#define must_succeed(x) do if (!(x)) abort(); while (0)
must_succeed(CryptAcquireContext(&prov, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_SILENT));
must_succeed(CryptGenRandom(prov, (DWORD)n, result));
must_succeed(CryptReleaseContext(prov, 0));
#undef must_succeed
}
#else
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
static void generate_system_random_bytes(size_t n, void *result) {
int fd;
if ((fd = open("/dev/urandom", O_RDONLY | O_NOCTTY | O_CLOEXEC)) < 0) {
err(EXIT_FAILURE, "open /dev/urandom");
}
for (;;) {
ssize_t res = read(fd, result, n);
if ((size_t) res == n) {
break;
}
if (res < 0) {
if (errno != EINTR) {
err(EXIT_FAILURE, "read /dev/urandom");
}
} else if (res == 0) {
errx(EXIT_FAILURE, "read /dev/urandom: end of file");
} else {
result = padd(result, (size_t) res);
n -= (size_t) res;
}
}
if (close(fd) < 0) {
err(EXIT_FAILURE, "close /dev/urandom");
}
}
#endif
static union hash_state state;
#if !defined(NDEBUG)
static volatile int curstate; /* To catch thread safety problems. */
#endif
FINALIZER(deinit_random) {
#if !defined(NDEBUG)
assert(curstate == 1);
curstate = 0;
#endif
memset(&state, 0, sizeof(union hash_state));
}
INITIALIZER(init_random) {
generate_system_random_bytes(32, &state);
REGISTER_FINALIZER(deinit_random);
#if !defined(NDEBUG)
assert(curstate == 0);
curstate = 1;
#endif
}
void generate_random_bytes_not_thread_safe(size_t n, void *result) {
#if !defined(NDEBUG)
assert(curstate == 1);
curstate = 2;
#endif
if (n == 0) {
#if !defined(NDEBUG)
assert(curstate == 2);
curstate = 1;
#endif
return;
}
for (;;) {
hash_permutation(&state);
if (n <= HASH_DATA_AREA) {
memcpy(result, &state, n);
#if !defined(NDEBUG)
assert(curstate == 2);
curstate = 1;
#endif
return;
} else {
memcpy(result, &state, HASH_DATA_AREA);
result = padd(result, HASH_DATA_AREA);
n -= HASH_DATA_AREA;
}
}
}