diff --git a/src/random.cpp b/src/random.cpp index 3e0c7610d..e66b9655a 100644 --- a/src/random.cpp +++ b/src/random.cpp @@ -1,486 +1,501 @@ // Copyright (c) 2009-2010 Satoshi Nakamoto // Copyright (c) 2009-2016 The Bitcoin Core developers // Distributed under the MIT software license, see the accompanying // file COPYING or http://www.opensource.org/licenses/mit-license.php. #include #ifdef WIN32 #include // for Windows API #include #endif #include #include // for LogPrint() #include #include // for WAIT_LOCK #include // for GetTime() #include #include #include #include #include #include #include #ifndef WIN32 #include #include #endif #ifdef HAVE_SYS_GETRANDOM #include #include #endif #if defined(HAVE_GETENTROPY) || \ (defined(HAVE_GETENTROPY_RAND) && defined(MAC_OSX)) #include #endif #if defined(HAVE_GETENTROPY_RAND) && defined(MAC_OSX) #include #endif #ifdef HAVE_SYSCTL_ARND #include #include // for ARRAYLEN #endif #if defined(__x86_64__) || defined(__amd64__) || defined(__i386__) #include #endif [[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; // Constrain the r variable to the eax:edx pair. __asm__ volatile("rdtsc" : "=A"(r)); return r; #elif !defined(_MSC_VER) && (defined(__x86_64__) || defined(__amd64__)) uint64_t r1 = 0, r2 = 0; // Constrain r1 to rax and r2 to rdx. __asm__ volatile("rdtsc" : "=a"(r1), "=d"(r2)); 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 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(uint8_t *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 vData(250000, 0); long ret = 0; unsigned long nSize = 0; // Bail out at more than 10MB of performance data const size_t nMaxSize = 10000000; 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; } // Grow size of buffer exponentially vData.resize(std::max((vData.size() * 3) / 2, nMaxSize)); } 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 { // Warn only once static bool warned = false; 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. */ static void GetDevURandom(uint8_t *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(uint8_t *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(uint8_t *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 Mutex cs_rng_state; static uint8_t rng_state[32] = {0}; static uint64_t rng_counter = 0; static void AddDataToRng(void *data, size_t len) { CSHA512 hasher; hasher.Write((const uint8_t *)&len, sizeof(len)); hasher.Write((const uint8_t *)data, len); uint8_t buf[64]; { WAIT_LOCK(cs_rng_state, lock); hasher.Write(rng_state, sizeof(rng_state)); hasher.Write((const uint8_t *)&rng_counter, sizeof(rng_counter)); ++rng_counter; hasher.Finalize(buf); memcpy(rng_state, buf + 32, 32); } memory_cleanse(buf, 64); } void GetStrongRandBytes(uint8_t *out, int num) { assert(num <= 32); CSHA512 hasher; uint8_t 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 { WAIT_LOCK(cs_rng_state, lock); hasher.Write(rng_state, sizeof(rng_state)); hasher.Write((const uint8_t *)&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::max() / nMax) * nMax; uint64_t nRand = 0; do { GetRandBytes((uint8_t *)&nRand, sizeof(nRand)); } while (nRand >= nRange); return (nRand % nMax); } int GetRandInt(int nMax) { return GetRand(nMax); } uint256 GetRandHash() { uint256 hash; GetRandBytes((uint8_t *)&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 FastRandomContext::randbytes(size_t len) { if (requires_seed) { RandomSeed(); } std::vector 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]; /* Tracks which bytes have been overwritten at least once */ bool overwritten[NUM_OS_RANDOM_BYTES] = {}; 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 this failed, bailed out after too many tries */ if (num_overwritten != NUM_OS_RANDOM_BYTES) { return false; } // 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 uint8_t *)&start, sizeof(start), 1); RAND_add((const uint8_t *)&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); } +FastRandomContext &FastRandomContext:: +operator=(FastRandomContext &&from) noexcept { + requires_seed = from.requires_seed; + rng = from.rng; + std::copy(std::begin(from.bytebuf), std::end(from.bytebuf), + std::begin(bytebuf)); + bytebuf_size = from.bytebuf_size; + bitbuf = from.bitbuf; + bitbuf_size = from.bitbuf_size; + from.requires_seed = true; + from.bytebuf_size = 0; + from.bitbuf_size = 0; + return *this; +} + void RandomInit() { RDRandInit(); } diff --git a/src/random.h b/src/random.h index 01fe64442..40d8392f7 100644 --- a/src/random.h +++ b/src/random.h @@ -1,184 +1,196 @@ // Copyright (c) 2009-2010 Satoshi Nakamoto // Copyright (c) 2009-2016 The Bitcoin Core developers // Distributed under the MIT software license, see the accompanying // file COPYING or http://www.opensource.org/licenses/mit-license.php. #ifndef BITCOIN_RANDOM_H #define BITCOIN_RANDOM_H #include #include #include #include #include /** * Seed OpenSSL PRNG with additional entropy data. */ void RandAddSeed(); /** * Functions to gather random data via the OpenSSL PRNG */ void GetRandBytes(uint8_t *buf, int num); uint64_t GetRand(uint64_t nMax); int GetRandInt(int nMax); uint256 GetRandHash(); /** * Add a little bit of randomness to the output of GetStrongRangBytes. * This sleeps for a millisecond, so should only be called when there is no * other work to be done. */ void RandAddSeedSleep(); /** * Function to gather random data from multiple sources, failing whenever any of * those source fail to provide a result. */ void GetStrongRandBytes(uint8_t *buf, int num); /** * Fast randomness source. This is seeded once with secure random data, but is * completely deterministic and insecure after that. * This class is not thread-safe. */ class FastRandomContext { private: bool requires_seed; ChaCha20 rng; uint8_t bytebuf[64]; int bytebuf_size; uint64_t bitbuf; int bitbuf_size; void RandomSeed(); void FillByteBuffer() { if (requires_seed) { RandomSeed(); } rng.Output(bytebuf, sizeof(bytebuf)); bytebuf_size = sizeof(bytebuf); } void FillBitBuffer() { bitbuf = rand64(); bitbuf_size = 64; } public: explicit FastRandomContext(bool fDeterministic = false); /** Initialize with explicit seed (only for testing) */ explicit FastRandomContext(const uint256 &seed); + // Do not permit copying a FastRandomContext (move it, or create a new one + // to get reseeded). + FastRandomContext(const FastRandomContext &) = delete; + FastRandomContext(FastRandomContext &&) = delete; + FastRandomContext &operator=(const FastRandomContext &) = delete; + + /** + * Move a FastRandomContext. If the original one is used again, it will be + * reseeded. + */ + FastRandomContext &operator=(FastRandomContext &&from) noexcept; + /** Generate a random 64-bit integer. */ uint64_t rand64() { if (bytebuf_size < 8) { FillByteBuffer(); } uint64_t ret = ReadLE64(bytebuf + 64 - bytebuf_size); bytebuf_size -= 8; return ret; } /** Generate a random (bits)-bit integer. */ uint64_t randbits(int bits) { if (bits == 0) { return 0; } else if (bits > 32) { return rand64() >> (64 - bits); } else { if (bitbuf_size < bits) { FillBitBuffer(); } uint64_t ret = bitbuf & (~uint64_t(0) >> (64 - bits)); bitbuf >>= bits; bitbuf_size -= bits; return ret; } } /** Generate a random integer in the range [0..range). */ uint64_t randrange(uint64_t range) { --range; int bits = CountBits(range); while (true) { uint64_t ret = randbits(bits); if (ret <= range) { return ret; } } } /** Generate random bytes. */ std::vector randbytes(size_t len); /** Generate a random 32-bit integer. */ uint32_t rand32() { return randbits(32); } /** generate a random uint256. */ uint256 rand256(); /** Generate a random boolean. */ bool randbool() { return randbits(1); } // Compatibility with the C++11 UniformRandomBitGenerator concept typedef uint64_t result_type; static constexpr uint64_t min() { return 0; } static constexpr uint64_t max() { return std::numeric_limits::max(); } inline uint64_t operator()() { return rand64(); } }; /** * More efficient than using std::shuffle on a FastRandomContext. * * This is more efficient as std::shuffle will consume entropy in groups of * 64 bits at the time and throw away most. * * This also works around a bug in libstdc++ std::shuffle that may cause * type::operator=(type&&) to be invoked on itself, which the library's * debug mode detects and panics on. This is a known issue, see * https://stackoverflow.com/questions/22915325/avoiding-self-assignment-in-stdshuffle */ template void Shuffle(I first, I last, R &&rng) { while (first != last) { size_t j = rng.randrange(last - first); if (j) { using std::swap; swap(*first, *(first + j)); } ++first; } } /** * Number of random bytes returned by GetOSRand. * When changing this constant make sure to change all call sites, and make * sure that the underlying OS APIs for all platforms support the number. * (many cap out at 256 bytes). */ static const ssize_t NUM_OS_RANDOM_BYTES = 32; /** * Get 32 bytes of system entropy. Do not use this in application code: use * GetStrongRandBytes instead. */ void GetOSRand(uint8_t *ent32); /** * Check that OS randomness is available and returning the requested number of * bytes. */ bool Random_SanityCheck(); /** Initialize the RNG. */ void RandomInit(); #endif // BITCOIN_RANDOM_H