95 lines
3.0 KiB
C++
95 lines
3.0 KiB
C++
//===-- RandomNumberGenerator.cpp - Implement RNG class -------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements deterministic random number generation (RNG).
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// The current implementation is NOT cryptographically secure as it uses
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// the C++11 <random> facilities.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/RandomNumberGenerator.h"
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#include "DebugOptions.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#ifdef _WIN32
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#include "llvm/Support/Windows/WindowsSupport.h"
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#else
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#include "Unix/Unix.h"
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#endif
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using namespace llvm;
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#define DEBUG_TYPE "rng"
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namespace {
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struct CreateSeed {
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static void *call() {
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return new cl::opt<uint64_t>(
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"rng-seed", cl::value_desc("seed"), cl::Hidden,
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cl::desc("Seed for the random number generator"), cl::init(0));
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}
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};
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} // namespace
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static ManagedStatic<cl::opt<uint64_t>, CreateSeed> Seed;
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void llvm::initRandomSeedOptions() { *Seed; }
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RandomNumberGenerator::RandomNumberGenerator(StringRef Salt) {
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LLVM_DEBUG(if (*Seed == 0) dbgs()
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<< "Warning! Using unseeded random number generator.\n");
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// Combine seed and salts using std::seed_seq.
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// Data: Seed-low, Seed-high, Salt
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// Note: std::seed_seq can only store 32-bit values, even though we
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// are using a 64-bit RNG. This isn't a problem since the Mersenne
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// twister constructor copies these correctly into its initial state.
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std::vector<uint32_t> Data;
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Data.resize(2 + Salt.size());
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Data[0] = *Seed;
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Data[1] = *Seed >> 32;
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llvm::copy(Salt, Data.begin() + 2);
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std::seed_seq SeedSeq(Data.begin(), Data.end());
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Generator.seed(SeedSeq);
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}
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RandomNumberGenerator::result_type RandomNumberGenerator::operator()() {
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return Generator();
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}
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// Get random vector of specified size
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std::error_code llvm::getRandomBytes(void *Buffer, size_t Size) {
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#ifdef _WIN32
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HCRYPTPROV hProvider;
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if (CryptAcquireContext(&hProvider, 0, 0, PROV_RSA_FULL,
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CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
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ScopedCryptContext ScopedHandle(hProvider);
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if (CryptGenRandom(hProvider, Size, static_cast<BYTE *>(Buffer)))
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return std::error_code();
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}
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return std::error_code(GetLastError(), std::system_category());
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#else
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int Fd = open("/dev/urandom", O_RDONLY);
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if (Fd != -1) {
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std::error_code Ret;
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ssize_t BytesRead = read(Fd, Buffer, Size);
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if (BytesRead == -1)
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Ret = std::error_code(errno, std::system_category());
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else if (BytesRead != static_cast<ssize_t>(Size))
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Ret = std::error_code(EIO, std::system_category());
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if (close(Fd) == -1)
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Ret = std::error_code(errno, std::system_category());
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return Ret;
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}
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return std::error_code(errno, std::system_category());
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#endif
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}
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