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// Copyright 2017 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/browser/conflicts/enumerate_shell_extensions_win.h"
#include <utility>
#include "base/bind.h"
#include "base/files/file_path.h"
#include "base/memory/ref_counted.h"
#include "base/sequenced_task_runner.h"
#include "base/strings/string16.h"
#include "base/strings/stringprintf.h"
#include "base/task/post_task.h"
#include "base/task/task_traits.h"
#include "base/threading/scoped_blocking_call.h"
#include "base/threading/sequenced_task_runner_handle.h"
#include "base/win/registry.h"
#include "chrome/browser/conflicts/module_info_util_win.h"
// The following link explains how Shell extensions are registered on Windows.
// Different types of handlers can be applied to different types of Shell
// objects.
// https://docs.microsoft.com/en-us/windows/desktop/shell/reg-shell-exts
namespace {
// The different kinds of shell objects that can be affected by a shell
// extension.
constexpr wchar_t kEverything[] = L"*";
constexpr wchar_t kAllFileSystemObjects[] = L"AllFileSystemObjects";
constexpr wchar_t kDesktopBackground[] = L"DesktopBackground";
constexpr wchar_t kDirectory[] = L"Directory";
constexpr wchar_t kDirectoryBackground[] = L"Directory\\Background";
constexpr wchar_t kDrive[] = L"Drive";
constexpr wchar_t kFolder[] = L"Folder";
constexpr wchar_t kNetServer[] = L"NetServer";
constexpr wchar_t kNetShare[] = L"NetShare";
constexpr wchar_t kNetwork[] = L"Network";
constexpr wchar_t kPrinters[] = L"Printers";
// Retrieves the path to the registry key that contains all the shell extensions
// of type |shell_extension_type| that apply to |shell_object_type|.
base::string16 GetShellExtensionTypePath(const wchar_t* shell_extension_type,
const wchar_t* shell_object_type) {
return base::StringPrintf(L"%ls\\shellex\\%ls", shell_object_type,
shell_extension_type);
}
// Returns the path to the DLL for an InProcServer32 registration.
base::FilePath GetInProcServerPath(const wchar_t* guid) {
base::string16 key = base::StringPrintf(kClassIdRegistryKeyFormat, guid);
base::win::RegKey clsid;
if (clsid.Open(HKEY_CLASSES_ROOT, key.c_str(), KEY_QUERY_VALUE) !=
ERROR_SUCCESS) {
return base::FilePath();
}
base::string16 dll_path;
if (clsid.ReadValue(L"", &dll_path) != ERROR_SUCCESS)
return base::FilePath();
return base::FilePath(std::move(dll_path));
}
// Reads all the shell extensions of type |shell_extension_type| that are
// applied to |shell_object_types| and forwards them to |callback|.
void ReadShellExtensions(
const wchar_t* shell_extension_type,
const wchar_t* shell_object_type,
const base::RepeatingCallback<void(const base::FilePath&)>& callback) {
base::string16 path =
GetShellExtensionTypePath(shell_extension_type, shell_object_type);
DCHECK_NE(path.back(), L'\\');
base::string16 guid;
for (base::win::RegistryKeyIterator iter(HKEY_CLASSES_ROOT, path.c_str());
iter.Valid(); ++iter) {
base::string16 shell_extension_reg_path = path + L"\\" + iter.Name();
base::win::RegKey reg_key(
HKEY_CLASSES_ROOT, shell_extension_reg_path.c_str(), KEY_QUERY_VALUE);
if (!reg_key.Valid())
continue;
guid.clear();
reg_key.ReadValue(nullptr, &guid);
if (guid.empty())
continue;
base::FilePath shell_extension_path = GetInProcServerPath(guid.c_str());
if (shell_extension_path.empty())
continue;
callback.Run(shell_extension_path);
}
}
// Reads all the shell extensions that are in the Approved list and forwards
// them to |callback|.
void ReadApprovedShellExtensions(
HKEY parent,
const base::RepeatingCallback<void(const base::FilePath&)>& callback) {
for (base::win::RegistryValueIterator iter(
parent, kApprovedShellExtensionRegistryKey);
iter.Valid(); ++iter) {
// Skip the key's default value.
if (!*iter.Name())
continue;
base::FilePath shell_extension_path = GetInProcServerPath(iter.Name());
if (shell_extension_path.empty())
continue;
callback.Run(shell_extension_path);
}
}
// Reads all the shell extensions of type ColumnHandlers.
void ReadColumnHandlers(
const base::RepeatingCallback<void(const base::FilePath&)>& callback) {
// Column handlers can only be applied to folders.
ReadShellExtensions(L"ColumnHandlers", kFolder, callback);
}
// Reads all the shell extensions of type CopyHookHandlers.
void ReadCopyHookHandlers(
const base::RepeatingCallback<void(const base::FilePath&)>& callback) {
static constexpr const wchar_t* kSupportedShellObjects[] = {
kDirectory, kPrinters,
};
for (const auto* shell_object : kSupportedShellObjects)
ReadShellExtensions(L"CopyHookHandlers", shell_object, callback);
}
// Reads all the shell extensions of type DragDropHandlers.
void ReadDragDropHandlers(
const base::RepeatingCallback<void(const base::FilePath&)>& callback) {
static constexpr const wchar_t* kSupportedShellObjects[] = {
kDirectory, kDrive, kFolder,
};
for (const auto* shell_object : kSupportedShellObjects)
ReadShellExtensions(L"DragDropHandlers", shell_object, callback);
}
// Reads all the shell extensions of type ContextMenuHandlers and
// PropertySheetHandlers.
void ReadContextMenuAndPropertySheetHandlers(
const base::RepeatingCallback<void(const base::FilePath&)>& callback) {
static constexpr const wchar_t* kHandlerTypes[] = {
L"ContextMenuHandlers", L"PropertySheetHandlers",
};
// This list is not exhaustive and does not cover cases where a shell
// extension is installed for a specific file extension or a specific
// executable. It should still pick up all the general-purpose shell
// extensions.
static constexpr const wchar_t* kSupportedShellObjects[] = {
kEverything,
kAllFileSystemObjects,
kFolder,
kDirectory,
kDirectoryBackground,
kDesktopBackground,
kDrive,
kNetwork,
kNetShare,
kNetServer,
kPrinters,
};
for (const auto* handler_type : kHandlerTypes) {
for (const auto* shell_object : kSupportedShellObjects)
ReadShellExtensions(handler_type, shell_object, callback);
}
}
// Retrieves the module size and time date stamp for the shell extension and
// forwards it to the callback on |task_runner|.
void OnShellExtensionPathEnumerated(
scoped_refptr<base::SequencedTaskRunner> task_runner,
OnShellExtensionEnumeratedCallback on_shell_extension_enumerated,
const base::FilePath& path) {
uint32_t size_of_image = 0;
uint32_t time_date_stamp = 0;
if (!GetModuleImageSizeAndTimeDateStamp(path, &size_of_image,
&time_date_stamp)) {
return;
}
task_runner->PostTask(
FROM_HERE, base::BindRepeating(std::move(on_shell_extension_enumerated),
path, size_of_image, time_date_stamp));
}
void EnumerateShellExtensionsOnBlockingSequence(
scoped_refptr<base::SequencedTaskRunner> task_runner,
OnShellExtensionEnumeratedCallback on_shell_extension_enumerated,
base::OnceClosure on_enumeration_finished) {
internal::EnumerateShellExtensionPaths(
base::BindRepeating(&OnShellExtensionPathEnumerated, task_runner,
std::move(on_shell_extension_enumerated)));
task_runner->PostTask(FROM_HERE, std::move(on_enumeration_finished));
}
} // namespace
const wchar_t kApprovedShellExtensionRegistryKey[] =
L"Software\\Microsoft\\Windows\\CurrentVersion\\Shell Extensions\\Approved";
void EnumerateShellExtensions(
OnShellExtensionEnumeratedCallback on_shell_extension_enumerated,
base::OnceClosure on_enumeration_finished) {
base::PostTaskWithTraits(
FROM_HERE,
{base::MayBlock(), base::TaskPriority::BEST_EFFORT,
base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN},
base::BindOnce(&EnumerateShellExtensionsOnBlockingSequence,
base::SequencedTaskRunnerHandle::Get(),
std::move(on_shell_extension_enumerated),
std::move(on_enumeration_finished)));
}
namespace internal {
void EnumerateShellExtensionPaths(
const base::RepeatingCallback<void(const base::FilePath&)>& callback) {
base::ScopedBlockingCall scoped_blocking_call(base::BlockingType::MAY_BLOCK);
ReadApprovedShellExtensions(HKEY_LOCAL_MACHINE, callback);
ReadApprovedShellExtensions(HKEY_CURRENT_USER, callback);
ReadColumnHandlers(callback);
ReadCopyHookHandlers(callback);
ReadDragDropHandlers(callback);
ReadContextMenuAndPropertySheetHandlers(callback);
}
} // namespace internal