blob: 003b2c734d347688776e0ecf70dba35e3c27be23 [file] [log] [blame]
// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/chrome_cleaner/engines/target/libraries.h"
#include <windows.h>
#include <delayimp.h>
#include <stdint.h>
#include <string.h>
#include <map>
#include <unordered_map>
#include <utility>
#include "base/callback.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/native_library.h"
#include "base/strings/string16.h"
#include "base/strings/string_piece.h"
#include "base/strings/utf_string_conversions.h"
#include "chrome/chrome_cleaner/engines/common/engine_resources.h"
#include "chrome/chrome_cleaner/os/digest_verifier.h"
#include "chrome/chrome_cleaner/os/file_path_sanitization.h"
#include "chrome/chrome_cleaner/os/resource_util.h"
#include "chrome/chrome_cleaner/os/system_util.h"
#include "chrome/chrome_cleaner/settings/settings.h"
#include "sandbox/win/src/sandbox_factory.h"
namespace chrome_cleaner {
namespace {
internal::LibraryPostExtractionCallback* g_post_extraction_callback = nullptr;
// Extracts engine DLLs from the embedded resources and writes them on disk.
// Should be called before any call to an engine library.
bool ExtractEmbeddedLibraries(Engine::Name engine,
const base::FilePath& extraction_dir) {
std::unordered_map<base::string16, int> resource_names_to_id =
for (const auto& name_id : resource_names_to_id) {
LOG(INFO) << "Extracting " << name_id.first << " to "
<< extraction_dir.value();
base::StringPiece library_data;
bool success =
LoadResourceOfKind(name_id.second, L"LIBRARY", &library_data);
if (!success) {
LOG(ERROR) << "Failed to load " << name_id.first << " from resources";
return false;
if (base::WriteFile(extraction_dir.Append(name_id.first),, library_data.size()) < 0) {
PLOG(ERROR) << "Failed to write " << name_id.first;
return false;
if (g_post_extraction_callback)
return true;
void VerifyEngineLibraryAllowed(Engine::Name engine,
const base::string16& requested_library) {
if (Settings::GetInstance()->run_without_sandbox_for_testing())
if (GetLibrariesToLoad(engine).count(requested_library) &&
!sandbox::SandboxFactory::GetTargetServices()) {
// Deny the load.
LOG(FATAL) << "Aborting due to attempt to load " << requested_library
<< " outside sandbox";
void VerifyRunningInSandbox() {
if (Settings::GetInstance()->run_without_sandbox_for_testing())
<< "Attempt to load engine libraries outside of the sandbox process";
extern "C" FARPROC WINAPI DllLoadHook(unsigned dliNotify, PDelayLoadInfo pdli) {
switch (dliNotify) {
case dliNotePreLoadLibrary: {
const base::string16 requested_library = base::ASCIIToUTF16(pdli->szDll);
const Engine::Name engine = Settings::GetInstance()->engine();
VerifyEngineLibraryAllowed(engine, requested_library);
const std::unordered_map<base::string16, base::string16>
library_replacements = GetLibraryTestReplacements(engine);
if (library_replacements.count(requested_library)) {
// Try loading the original DLL first, then try the replacement.
HMODULE library = ::LoadLibrary(requested_library.c_str());
if (library == nullptr) {
const base::string16& fallback_library =
PLOG(WARNING) << "Could not load " << requested_library
<< "; falling back to " << fallback_library;
library = ::LoadLibrary(fallback_library.c_str());
PLOG_IF(FATAL, library == nullptr)
<< "Failed to load " << fallback_library;
return reinterpret_cast<FARPROC>(library);
return nullptr;
return nullptr;
extern "C" const PfnDliHook __pfnDliNotifyHook2 = DllLoadHook;
} // namespace
namespace internal {
void SetLibraryPostExtractionCallbackForTesting(
LibraryPostExtractionCallback post_extraction_callback) {
g_post_extraction_callback = new LibraryPostExtractionCallback();
*g_post_extraction_callback = std::move(post_extraction_callback);
void ClearLibraryPostExtractionCallbackForTesting() {
delete g_post_extraction_callback;
g_post_extraction_callback = nullptr;
} // namespace internal
bool LoadAndValidateLibraries(Engine::Name engine,
const base::FilePath& extraction_dir) {
// This function is invoked in the sandbox target process before LowerToken is
// called, so the process will have read access to the DLL files. For
// libraries using DELAYLOAD, DllLoadHook will also be called some time later
// (when the first attempt is made to access a symbol defined in the library.)
// This should happen after LowerToken.
// Calling LoadLibrary here will just load the library into memory, but not
// update the DELAYLOAD thunks to point to its symbols, so it won't be used
// for anything. But it does mean that DllLoadHook will succeed in "loading"
// the library even if the sandbox would usually block access (because it
// just gets another handle to the library already in memory.) DllLoadHooks
// will then update the thunks so that the library is actually used.
// Some engine libraries are dynamically loaded by the engine, not through
// DELAYLOAD. Again calling LoadLibrary here will allow the engine to access
// them despite the sandbox. Also it will mark the file in use, ensuring that
// the version that is validated here is not overwritten before it is loaded.
const std::set<base::string16> libraries_to_load = GetLibrariesToLoad(engine);
if (libraries_to_load.empty())
return true;
// Proceed even if the library extraction fails. It happens to the elevated
// cleaner process as it is executed in the same directory as the non-elevated
// one, and the directory already has libraries on the disk. If the libraries
// are corrupted, DigestVerifier will catch it below.
ExtractEmbeddedLibraries(engine, extraction_dir);
// If modules might be replaced for testing, disable validation and do not
// fail on loading errors. The real DLL's may not be present, so don't abort
// just because they can't be loaded.
const bool enable_validation = GetLibraryTestReplacements(engine).empty();
<< "Library validation should not be disabled in official build";
scoped_refptr<DigestVerifier> digest_verifier =
// Load all libraries and validate them if required.
for (const base::string16& library_name : libraries_to_load) {
base::FilePath dll_path = extraction_dir.Append(library_name);
// Open a handle to the DLL before verifying it.
base::NativeLibraryLoadError error;
base::LoadNativeLibrary(dll_path, &error); // Return value leaks.
if (error.code && enable_validation) {
LOG(ERROR) << "Error loading library " << SanitizePath(dll_path) << ": "
<< error.ToString();
return false;
if (enable_validation && !digest_verifier->IsKnownFile(dll_path)) {
LOG(ERROR) << SanitizePath(dll_path) << " does not have a valid digest";
return false;
return true;
} // namespace chrome_cleaner