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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2017 The Starwels developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <random.h>
#include <crypto/sha512.h>
#include <support/cleanse.h>
#ifdef WIN32
#include <compat.h> // for Windows API
#include <wincrypt.h>
#endif
#include <util.h> // for LogPrint()
#include <utilstrencodings.h> // for GetTime()
#include <stdlib.h>
#include <limits>
#include <chrono>
#include <thread>
#ifndef WIN32
#include <sys/time.h>
#endif
#ifdef HAVE_SYS_GETRANDOM
#include <sys/syscall.h>
#include <linux/random.h>
#endif
#if defined(HAVE_GETENTROPY) || (defined(HAVE_GETENTROPY_RAND) && defined(MAC_OSX))
#include <unistd.h>
#endif
#if defined(HAVE_GETENTROPY_RAND) && defined(MAC_OSX)
#include <sys/random.h>
#endif
#ifdef HAVE_SYSCTL_ARND
#include <sys/sysctl.h>
#endif
#include <mutex>
#if defined(__x86_64__) || defined(__amd64__) || defined(__i386__)
#include <cpuid.h>
#endif
#include <openssl/err.h>
#include <openssl/rand.h>
[[noreturn]] static void RandFailure()
{
LogPrintf("Failed to read randomness, aborting\n");
std::abort();
}
static inline int64_t GetPerformanceCounter()
{
// Read the hardware time stamp counter when available.
// See https://en.wikipedia.org/wiki/Time_Stamp_Counter for more information.
#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
return __rdtsc();
#elif !defined(_MSC_VER) && defined(__i386__)
uint64_t r = 0;
__asm__ volatile ("rdtsc" : "=A"(r)); // Constrain the r variable to the eax:edx pair.
return r;
#elif !defined(_MSC_VER) && (defined(__x86_64__) || defined(__amd64__))
uint64_t r1 = 0, r2 = 0;
__asm__ volatile ("rdtsc" : "=a"(r1), "=d"(r2)); // Constrain r1 to rax and r2 to rdx.
return (r2 << 32) | r1;
#else
// Fall back to using C++11 clock (usually microsecond or nanosecond precision)
return std::chrono::high_resolution_clock::now().time_since_epoch().count();
#endif
}
#if defined(__x86_64__) || defined(__amd64__) || defined(__i386__)
static std::atomic<bool> hwrand_initialized{false};
static bool rdrand_supported = false;
static constexpr uint32_t CPUID_F1_ECX_RDRAND = 0x40000000;
static void RDRandInit()
{
uint32_t eax, ebx, ecx, edx;
if (__get_cpuid(1, &eax, &ebx, &ecx, &edx) && (ecx & CPUID_F1_ECX_RDRAND)) {
LogPrintf("Using RdRand as an additional entropy source\n");
rdrand_supported = true;
}
hwrand_initialized.store(true);
}
#else
static void RDRandInit() {}
#endif
static bool GetHWRand(unsigned char* ent32) {
#if defined(__x86_64__) || defined(__amd64__) || defined(__i386__)
assert(hwrand_initialized.load(std::memory_order_relaxed));
if (rdrand_supported) {
uint8_t ok;
// Not all assemblers support the rdrand instruction, write it in hex.
#ifdef __i386__
for (int iter = 0; iter < 4; ++iter) {
uint32_t r1, r2;
__asm__ volatile (".byte 0x0f, 0xc7, 0xf0;" // rdrand %eax
".byte 0x0f, 0xc7, 0xf2;" // rdrand %edx
"setc %2" :
"=a"(r1), "=d"(r2), "=q"(ok) :: "cc");
if (!ok) return false;
WriteLE32(ent32 + 8 * iter, r1);
WriteLE32(ent32 + 8 * iter + 4, r2);
}
#else
uint64_t r1, r2, r3, r4;
__asm__ volatile (".byte 0x48, 0x0f, 0xc7, 0xf0, " // rdrand %rax
"0x48, 0x0f, 0xc7, 0xf3, " // rdrand %rbx
"0x48, 0x0f, 0xc7, 0xf1, " // rdrand %rcx
"0x48, 0x0f, 0xc7, 0xf2; " // rdrand %rdx
"setc %4" :
"=a"(r1), "=b"(r2), "=c"(r3), "=d"(r4), "=q"(ok) :: "cc");
if (!ok) return false;
WriteLE64(ent32, r1);
WriteLE64(ent32 + 8, r2);
WriteLE64(ent32 + 16, r3);
WriteLE64(ent32 + 24, r4);
#endif
return true;
}
#endif
return false;
}
void RandAddSeed()
{
// Seed with CPU performance counter
int64_t nCounter = GetPerformanceCounter();
RAND_add(&nCounter, sizeof(nCounter), 1.5);
memory_cleanse((void*)&nCounter, sizeof(nCounter));
}
static void RandAddSeedPerfmon()
{
RandAddSeed();
#ifdef WIN32
// Don't need this on Linux, OpenSSL automatically uses /dev/urandom
// Seed with the entire set of perfmon data
// This can take up to 2 seconds, so only do it every 10 minutes
static int64_t nLastPerfmon;
if (GetTime() < nLastPerfmon + 10 * 60)
return;
nLastPerfmon = GetTime();
std::vector<unsigned char> vData(250000, 0);
long ret = 0;
unsigned long nSize = 0;
const size_t nMaxSize = 10000000; // Bail out at more than 10MB of performance data
while (true) {
nSize = vData.size();
ret = RegQueryValueExA(HKEY_PERFORMANCE_DATA, "Global", nullptr, nullptr, vData.data(), &nSize);
if (ret != ERROR_MORE_DATA || vData.size() >= nMaxSize)
break;
vData.resize(std::max((vData.size() * 3) / 2, nMaxSize)); // Grow size of buffer exponentially
}
RegCloseKey(HKEY_PERFORMANCE_DATA);
if (ret == ERROR_SUCCESS) {
RAND_add(vData.data(), nSize, nSize / 100.0);
memory_cleanse(vData.data(), nSize);
LogPrint(BCLog::RAND, "%s: %lu bytes\n", __func__, nSize);
} else {
static bool warned = false; // Warn only once
if (!warned) {
LogPrintf("%s: Warning: RegQueryValueExA(HKEY_PERFORMANCE_DATA) failed with code %i\n", __func__, ret);
warned = true;
}
}
#endif
}
#ifndef WIN32
/** Fallback: get 32 bytes of system entropy from /dev/urandom. The most
* compatible way to get cryptographic randomness on UNIX-ish platforms.
*/
void GetDevURandom(unsigned char *ent32)
{
int f = open("/dev/urandom", O_RDONLY);
if (f == -1) {
RandFailure();
}
int have = 0;
do {
ssize_t n = read(f, ent32 + have, NUM_OS_RANDOM_BYTES - have);
if (n <= 0 || n + have > NUM_OS_RANDOM_BYTES) {
close(f);
RandFailure();
}
have += n;
} while (have < NUM_OS_RANDOM_BYTES);
close(f);
}
#endif
/** Get 32 bytes of system entropy. */
void GetOSRand(unsigned char *ent32)
{
#if defined(WIN32)
HCRYPTPROV hProvider;
int ret = CryptAcquireContextW(&hProvider, nullptr, nullptr, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
if (!ret) {
RandFailure();
}
ret = CryptGenRandom(hProvider, NUM_OS_RANDOM_BYTES, ent32);
if (!ret) {
RandFailure();
}
CryptReleaseContext(hProvider, 0);
#elif defined(HAVE_SYS_GETRANDOM)
/* Linux. From the getrandom(2) man page:
* "If the urandom source has been initialized, reads of up to 256 bytes
* will always return as many bytes as requested and will not be
* interrupted by signals."
*/
int rv = syscall(SYS_getrandom, ent32, NUM_OS_RANDOM_BYTES, 0);
if (rv != NUM_OS_RANDOM_BYTES) {
if (rv < 0 && errno == ENOSYS) {
/* Fallback for kernel <3.17: the return value will be -1 and errno
* ENOSYS if the syscall is not available, in that case fall back
* to /dev/urandom.
*/
GetDevURandom(ent32);
} else {
RandFailure();
}
}
#elif defined(HAVE_GETENTROPY) && defined(__OpenBSD__)
/* On OpenBSD this can return up to 256 bytes of entropy, will return an
* error if more are requested.
* The call cannot return less than the requested number of bytes.
getentropy is explicitly limited to openbsd here, as a similar (but not
the same) function may exist on other platforms via glibc.
*/
if (getentropy(ent32, NUM_OS_RANDOM_BYTES) != 0) {
RandFailure();
}
#elif defined(HAVE_GETENTROPY_RAND) && defined(MAC_OSX)
// We need a fallback for OSX < 10.12
if (&getentropy != nullptr) {
if (getentropy(ent32, NUM_OS_RANDOM_BYTES) != 0) {
RandFailure();
}
} else {
GetDevURandom(ent32);
}
#elif defined(HAVE_SYSCTL_ARND)
/* FreeBSD and similar. It is possible for the call to return less
* bytes than requested, so need to read in a loop.
*/
static const int name[2] = {CTL_KERN, KERN_ARND};
int have = 0;
do {
size_t len = NUM_OS_RANDOM_BYTES - have;
if (sysctl(name, ARRAYLEN(name), ent32 + have, &len, nullptr, 0) != 0) {
RandFailure();
}
have += len;
} while (have < NUM_OS_RANDOM_BYTES);
#else
/* Fall back to /dev/urandom if there is no specific method implemented to
* get system entropy for this OS.
*/
GetDevURandom(ent32);
#endif
}
void GetRandBytes(unsigned char* buf, int num)
{
if (RAND_bytes(buf, num) != 1) {
RandFailure();
}
}
static void AddDataToRng(void* data, size_t len);
void RandAddSeedSleep()
{
int64_t nPerfCounter1 = GetPerformanceCounter();
std::this_thread::sleep_for(std::chrono::milliseconds(1));
int64_t nPerfCounter2 = GetPerformanceCounter();
// Combine with and update state
AddDataToRng(&nPerfCounter1, sizeof(nPerfCounter1));
AddDataToRng(&nPerfCounter2, sizeof(nPerfCounter2));
memory_cleanse(&nPerfCounter1, sizeof(nPerfCounter1));
memory_cleanse(&nPerfCounter2, sizeof(nPerfCounter2));
}
static std::mutex cs_rng_state;
static unsigned char rng_state[32] = {0};
static uint64_t rng_counter = 0;
static void AddDataToRng(void* data, size_t len) {
CSHA512 hasher;
hasher.Write((const unsigned char*)&len, sizeof(len));
hasher.Write((const unsigned char*)data, len);
unsigned char buf[64];
{
std::unique_lock<std::mutex> lock(cs_rng_state);
hasher.Write(rng_state, sizeof(rng_state));
hasher.Write((const unsigned char*)&rng_counter, sizeof(rng_counter));
++rng_counter;
hasher.Finalize(buf);
memcpy(rng_state, buf + 32, 32);
}
memory_cleanse(buf, 64);
}
void GetStrongRandBytes(unsigned char* out, int num)
{
assert(num <= 32);
CSHA512 hasher;
unsigned char buf[64];
// First source: OpenSSL's RNG
RandAddSeedPerfmon();
GetRandBytes(buf, 32);
hasher.Write(buf, 32);
// Second source: OS RNG
GetOSRand(buf);
hasher.Write(buf, 32);
// Third source: HW RNG, if available.
if (GetHWRand(buf)) {
hasher.Write(buf, 32);
}
// Combine with and update state
{
std::unique_lock<std::mutex> lock(cs_rng_state);
hasher.Write(rng_state, sizeof(rng_state));
hasher.Write((const unsigned char*)&rng_counter, sizeof(rng_counter));
++rng_counter;
hasher.Finalize(buf);
memcpy(rng_state, buf + 32, 32);
}
// Produce output
memcpy(out, buf, num);
memory_cleanse(buf, 64);
}
uint64_t GetRand(uint64_t nMax)
{
if (nMax == 0)
return 0;
// The range of the random source must be a multiple of the modulus
// to give every possible output value an equal possibility
uint64_t nRange = (std::numeric_limits<uint64_t>::max() / nMax) * nMax;
uint64_t nRand = 0;
do {
GetRandBytes((unsigned char*)&nRand, sizeof(nRand));
} while (nRand >= nRange);
return (nRand % nMax);
}
int GetRandInt(int nMax)
{
return GetRand(nMax);
}
uint256 GetRandHash()
{
uint256 hash;
GetRandBytes((unsigned char*)&hash, sizeof(hash));
return hash;
}
void FastRandomContext::RandomSeed()
{
uint256 seed = GetRandHash();
rng.SetKey(seed.begin(), 32);
requires_seed = false;
}
uint256 FastRandomContext::rand256()
{
if (bytebuf_size < 32) {
FillByteBuffer();
}
uint256 ret;
memcpy(ret.begin(), bytebuf + 64 - bytebuf_size, 32);
bytebuf_size -= 32;
return ret;
}
std::vector<unsigned char> FastRandomContext::randbytes(size_t len)
{
std::vector<unsigned char> ret(len);
if (len > 0) {
rng.Output(&ret[0], len);
}
return ret;
}
FastRandomContext::FastRandomContext(const uint256& seed) : requires_seed(false), bytebuf_size(0), bitbuf_size(0)
{
rng.SetKey(seed.begin(), 32);
}
bool Random_SanityCheck()
{
uint64_t start = GetPerformanceCounter();
/* This does not measure the quality of randomness, but it does test that
* OSRandom() overwrites all 32 bytes of the output given a maximum
* number of tries.
*/
static const ssize_t MAX_TRIES = 1024;
uint8_t data[NUM_OS_RANDOM_BYTES];
bool overwritten[NUM_OS_RANDOM_BYTES] = {}; /* Tracks which bytes have been overwritten at least once */
int num_overwritten;
int tries = 0;
/* Loop until all bytes have been overwritten at least once, or max number tries reached */
do {
memset(data, 0, NUM_OS_RANDOM_BYTES);
GetOSRand(data);
for (int x=0; x < NUM_OS_RANDOM_BYTES; ++x) {
overwritten[x] |= (data[x] != 0);
}
num_overwritten = 0;
for (int x=0; x < NUM_OS_RANDOM_BYTES; ++x) {
if (overwritten[x]) {
num_overwritten += 1;
}
}
tries += 1;
} while (num_overwritten < NUM_OS_RANDOM_BYTES && tries < MAX_TRIES);
if (num_overwritten != NUM_OS_RANDOM_BYTES) return false; /* If this failed, bailed out after too many tries */
// Check that GetPerformanceCounter increases at least during a GetOSRand() call + 1ms sleep.
std::this_thread::sleep_for(std::chrono::milliseconds(1));
uint64_t stop = GetPerformanceCounter();
if (stop == start) return false;
// We called GetPerformanceCounter. Use it as entropy.
RAND_add((const unsigned char*)&start, sizeof(start), 1);
RAND_add((const unsigned char*)&stop, sizeof(stop), 1);
return true;
}
FastRandomContext::FastRandomContext(bool fDeterministic) : requires_seed(!fDeterministic), bytebuf_size(0), bitbuf_size(0)
{
if (!fDeterministic) {
return;
}
uint256 seed;
rng.SetKey(seed.begin(), 32);
}
void RandomInit()
{
RDRandInit();
}