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