| // Copyright 2012 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include"base/rand_util.h" |
| |
| #include<windows.h> |
| |
| #include<stddef.h> |
| #include<stdint.h> |
| |
| #include<algorithm> |
| #include<atomic> |
| #include<limits> |
| |
| #include"base/check.h" |
| #include"base/feature_list.h" |
| #include"third_party/boringssl/src/include/openssl/rand.h" |
| |
| // Prototype for ProcessPrng. |
| // See: https://learn.microsoft.com/en-us/windows/win32/seccng/processprng |
| extern"C"{ |
| BOOL WINAPIProcessPrng(PBYTE pbData, SIZE_T cbData); |
| } |
| |
| namespace base{ |
| |
| namespace internal{ |
| |
| namespace{ |
| |
| // The BoringSSl helpers are duplicated in rand_util_fuchsia.cc and |
| // rand_util_posix.cc. |
| std::atomic<bool> g_use_boringssl; |
| |
| BASE_FEATURE(kUseBoringSSLForRandBytes, |
| "UseBoringSSLForRandBytes", |
| FEATURE_DISABLED_BY_DEFAULT); |
| |
| }// namespace |
| |
| voidConfigureBoringSSLBackedRandBytesFieldTrial(){ |
| g_use_boringssl.store(FeatureList::IsEnabled(kUseBoringSSLForRandBytes), |
| std::memory_order_relaxed); |
| } |
| |
| boolUseBoringSSLForRandBytes(){ |
| return g_use_boringssl.load(std::memory_order_relaxed); |
| } |
| |
| }// namespace internal |
| |
| namespace{ |
| |
| // Import bcryptprimitives!ProcessPrng rather than cryptbase!RtlGenRandom to |
| // avoid opening a handle to \\Device\KsecDD in the renderer. |
| decltype(&ProcessPrng)GetProcessPrng(){ |
| HMODULE hmod=LoadLibraryW(L"bcryptprimitives.dll"); |
| CHECK(hmod); |
| decltype(&ProcessPrng) process_prng_fn= |
| reinterpret_cast<decltype(&ProcessPrng)>( |
| GetProcAddress(hmod,"ProcessPrng")); |
| CHECK(process_prng_fn); |
| return process_prng_fn; |
| } |
| |
| voidRandBytesInternal(span<uint8_t> output,bool avoid_allocation){ |
| if(!avoid_allocation&& internal::UseBoringSSLForRandBytes()){ |
| // BoringSSL's RAND_bytes always returns 1. Any error aborts the program. |
| (void)RAND_bytes(output.data(), output.size()); |
| return; |
| } |
| |
| staticdecltype(&ProcessPrng) process_prng_fn=GetProcessPrng(); |
| BOOL success= |
| process_prng_fn(static_cast<BYTE*>(output.data()), output.size()); |
| // ProcessPrng is documented to always return TRUE. |
| CHECK(success); |
| } |
| |
| }// namespace |
| |
| voidRandBytes(span<uint8_t> output){ |
| RandBytesInternal(output,/*avoid_allocation=*/false); |
| } |
| |
| namespace internal{ |
| |
| doubleRandDoubleAvoidAllocation(){ |
| uint64_t number; |
| RandBytesInternal(byte_span_from_ref(number), |
| /*avoid_allocation=*/true); |
| // This transformation is explained in rand_util.cc. |
| return(number>>11)*0x1.0p-53; |
| } |
| |
| }// namespace internal |
| |
| }// namespace base |
