// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40285824): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
#include "chrome/install_static/policy_path_parser.h"
#include <assert.h>
#include <shlobj.h>
#include <stddef.h>
#include <stdlib.h>
#include <wtsapi32.h>
#include <memory>
namespace {
constexpr WCHAR kMachineNamePolicyVarName[] = L"${machine_name}";
constexpr WCHAR kUserNamePolicyVarName[] = L"${user_name}";
constexpr WCHAR kWinDocumentsFolderVarName[] = L"${documents}";
constexpr WCHAR kWinLocalAppDataFolderVarName[] = L"${local_app_data}";
constexpr WCHAR kWinRoamingAppDataFolderVarName[] = L"${roaming_app_data}";
constexpr WCHAR kWinProfileFolderVarName[] = L"${profile}";
constexpr WCHAR kWinProgramDataFolderVarName[] = L"${global_app_data}";
constexpr WCHAR kWinProgramFilesFolderVarName[] = L"${program_files}";
constexpr WCHAR kWinWindowsFolderVarName[] = L"${windows}";
constexpr WCHAR kWinClientName[] = L"${client_name}";
constexpr WCHAR kWinSessionName[] = L"${session_name}";
struct WinFolderNamesToCSIDLMapping {
const WCHAR* name;
int id;
};
// Mapping from variable names to Windows CSIDL ids.
constexpr WinFolderNamesToCSIDLMapping kWinFolderMapping[] = {
{kWinWindowsFolderVarName, CSIDL_WINDOWS},
{kWinProgramFilesFolderVarName, CSIDL_PROGRAM_FILES},
{kWinProgramDataFolderVarName, CSIDL_COMMON_APPDATA},
{kWinProfileFolderVarName, CSIDL_PROFILE},
{kWinLocalAppDataFolderVarName, CSIDL_LOCAL_APPDATA},
{kWinRoamingAppDataFolderVarName, CSIDL_APPDATA},
{kWinDocumentsFolderVarName, CSIDL_PERSONAL}};
template <class FunctionType>
struct ScopedFunctionHelper {
ScopedFunctionHelper(const wchar_t* library_name, const char* function_name) {
library_ = LoadLibrary(library_name);
assert(library_);
if (library_) {
// Strip off any leading :: that may have come from stringifying the
// function's name.
if (function_name[0] == ':' && function_name[1] == ':' &&
function_name[2] && function_name[2] != ':') {
function_name += 2;
}
function_ = reinterpret_cast<FunctionType*>(
GetProcAddress(library_, function_name));
assert(function_);
}
}
~ScopedFunctionHelper() {
if (library_)
FreeLibrary(library_);
}
template <class... Args>
auto operator()(Args... a) {
return function_(a...);
}
private:
HMODULE library_;
FunctionType* function_;
};
#define SCOPED_LOAD_FUNCTION(library, function) \
ScopedFunctionHelper<decltype(function)>(library, #function)
} // namespace
namespace install_static {
// Replaces all variable occurrences in the policy string with the respective
// system settings values.
// Note that this uses GetProcAddress to load DLLs that cannot be loaded before
// the blacklist in the DllMain of chrome_elf has been applied. This function
// should only be used after DllMain() has run.
std::wstring ExpandPathVariables(const std::wstring& untranslated_string) {
std::wstring result(untranslated_string);
if (result.length() == 0)
return result;
// Sanitize quotes in case of any around the whole string.
if (result.length() > 1 &&
((result.front() == L'"' && result.back() == L'"') ||
(result.front() == L'\'' && result.back() == L'\''))) {
// Strip first and last char which should be matching quotes now.
result.pop_back();
result.erase(0, 1);
}
auto sh_get_special_folder_path =
SCOPED_LOAD_FUNCTION(L"shell32.dll", ::SHGetSpecialFolderPathW);
// First translate all path variables we recognize.
for (size_t i = 0; i < _countof(kWinFolderMapping); ++i) {
size_t position = result.find(kWinFolderMapping[i].name);
if (position != std::wstring::npos) {
size_t variable_length = wcslen(kWinFolderMapping[i].name);
WCHAR path[MAX_PATH];
if (!sh_get_special_folder_path(nullptr, path, kWinFolderMapping[i].id,
false)) {
path[0] = 0;
}
std::wstring path_string(path);
// Remove a trailing slash if there is any but also only if the rest of
// the string contains one right after to avoid ending in a drive only
// value situation. This usually won't happen but if the value of this
// special folder is the root of a drive it will be presented as D:\.
if (!path_string.empty() && path_string.back() == L'\\' &&
result.length() > position + variable_length &&
result[position + variable_length] == L'\\') {
path_string.pop_back();
}
result.replace(position, variable_length, path_string);
}
}
// Next translate other windows specific variables.
auto get_user_name = SCOPED_LOAD_FUNCTION(L"advapi32.dll", ::GetUserNameW);
size_t position = result.find(kUserNamePolicyVarName);
if (position != std::wstring::npos) {
DWORD return_length = 0;
get_user_name(nullptr, &return_length);
if (return_length != 0) {
std::unique_ptr<WCHAR[]> username(new WCHAR[return_length]);
get_user_name(username.get(), &return_length);
std::wstring username_string(username.get());
result.replace(position, wcslen(kUserNamePolicyVarName), username_string);
}
}
position = result.find(kMachineNamePolicyVarName);
if (position != std::wstring::npos) {
DWORD return_length = 0;
::GetComputerNameEx(ComputerNamePhysicalDnsHostname, nullptr,
&return_length);
if (return_length != 0) {
std::unique_ptr<WCHAR[]> machinename(new WCHAR[return_length]);
::GetComputerNameEx(ComputerNamePhysicalDnsHostname, machinename.get(),
&return_length);
std::wstring machinename_string(machinename.get());
result.replace(position, wcslen(kMachineNamePolicyVarName),
machinename_string);
}
}
auto wts_query_session_information =
SCOPED_LOAD_FUNCTION(L"wtsapi32.dll", ::WTSQuerySessionInformationW);
auto wts_free_memory = SCOPED_LOAD_FUNCTION(L"wtsapi32.dll", ::WTSFreeMemory);
position = result.find(kWinClientName);
if (position != std::wstring::npos) {
LPWSTR buffer = nullptr;
DWORD buffer_length = 0;
if (wts_query_session_information(WTS_CURRENT_SERVER, WTS_CURRENT_SESSION,
WTSClientName, &buffer, &buffer_length)) {
std::wstring clientname_string(buffer);
result.replace(position, wcslen(kWinClientName), clientname_string);
wts_free_memory(buffer);
}
}
position = result.find(kWinSessionName);
if (position != std::wstring::npos) {
LPWSTR buffer = nullptr;
DWORD buffer_length = 0;
if (wts_query_session_information(WTS_CURRENT_SERVER, WTS_CURRENT_SESSION,
WTSWinStationName, &buffer,
&buffer_length)) {
std::wstring sessionname_string(buffer);
result.replace(position, wcslen(kWinSessionName), sessionname_string);
wts_free_memory(buffer);
}
}
// TODO(pastarmovj): Consider reorganizing this code once there are even more
// variables to be supported. The search for the var and its replacement can
// be extracted as common functionality.
return result;
}
} // namespace install_static
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