Util: added secure_zero_memory with type safety checks

CMakeLists.txt

@@ -32,6 +32,8 @@ option(DEV_DEBUG "[Developer only] Compile a debug build" OFF)
 
 set_property(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} PROPERTY VS_STARTUP_PROJECT p2pool)
 
+set(BUILD_TESTING OFF CACHE BOOL "CMake's CTest module")
+
 if (CMAKE_CXX_COMPILER_ID MATCHES MSVC)
 	include(cmake/msvc_libs.cmake)
 endif()

src/p2pool.cpp

@@ -806,6 +806,7 @@ void p2pool::send_aux_job_donation()
 	}
 
 	Params::AuthorKey key;
+	ON_SCOPE_LEAVE([&key](){ secure_zero_memory(key); });
 
 	if (f.tellg() != static_cast<std::streampos>(sizeof(key))) {
 		LOGERR(1, "send_aux_job_donation: " << m_params->m_authorKeyFile << " has an invalid size");
@@ -869,8 +870,6 @@ void p2pool::send_aux_job_donation()
 		return;
 	}
 
-	OPENSSL_cleanse(&key, sizeof(key));
-
 	job.insert(job.end(), signature, signature + sizeof(signature));
 
 	m_p2pServer->broadcast_aux_job_donation_async(job.data(), static_cast<uint32_t>(job.size()), timestamp);

src/util.cpp

@@ -124,6 +124,32 @@ void fixup_path(std::string& path)
 	}
 }
 
+// Tell the compiler to not optimize secure_zero_memory and hope that it listens
+
+#ifdef _MSC_VER
+#pragma optimize("", off)
+#endif
+
+void
+#if defined(__clang__)
+__attribute__((optnone))
+#elif defined(__GNUC__)
+__attribute__((optimize("O0")))
+#endif
+secure_zero_memory(volatile void* data, size_t size)
+{
+	volatile uint8_t* p = reinterpret_cast<volatile uint8_t*>(data);
+	volatile uint8_t* e = reinterpret_cast<volatile uint8_t*>(data) + size;
+
+	while (p < e) {
+		*(p++) = 0;
+	}
+}
+
+#ifdef _MSC_VER
+#pragma optimize("", on)
+#endif
+
 const uint8_t ED25519_MASTER_PUBLIC_KEY[32] = {51,175,37,73,203,241,188,115,195,255,123,53,218,120,90,74,186,240,82,178,67,139,124,91,180,106,188,181,187,51,236,10};
 
 std::string DATA_DIR;

src/util.h

@@ -386,6 +386,17 @@ std::string p2pool_version();
 
 void fixup_path(std::string& path);
 
+void secure_zero_memory(volatile void* data, size_t size);
+
+template<typename T>
+FORCEINLINE void secure_zero_memory(T& value)
+{
+	static_assert(!std::is_pointer_v<T>, "Trying to zero a pointer instead of data it points to");
+	static_assert(std::is_trivially_copyable_v<T>, "Trying to zero a complex data type");
+
+	secure_zero_memory(&value, sizeof(T));
+}
+
 } // namespace p2pool
 
 void memory_tracking_start();