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- // Copyright 2018 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/elevation_service/elevated_recovery_impl.h"
- #include <objbase.h>
- #include <string>
- #include <utility>
- #include "base/base_paths.h"
- #include "base/bind.h"
- #include "base/callback_helpers.h"
- #include "base/command_line.h"
- #include "base/files/file_enumerator.h"
- #include "base/files/file_path.h"
- #include "base/files/file_util.h"
- #include "base/files/scoped_temp_dir.h"
- #include "base/logging.h"
- #include "base/path_service.h"
- #include "base/process/launch.h"
- #include "base/process/process.h"
- #include "base/strings/utf_string_conversions.h"
- #include "base/version.h"
- #include "base/win/scoped_process_information.h"
- #include "chrome/install_static/install_util.h"
- #include "third_party/zlib/google/zip.h"
- namespace elevation_service {
- namespace {
- // Input CRX files over 10 MB are considered invalid.
- constexpr int64_t kMaxFileSize = 10u * 1000u * 1000u;
- // The hard-coded file name that the Recovery CRX is copied to.
- constexpr base::FilePath::CharType kCRXFileName[] =
- FILE_PATH_LITERAL("ChromeRecoveryCRX.crx");
- // The hard-coded Recovery subdirectory where the CRX is unpacked and executed.
- constexpr base::FilePath::CharType kRecoveryDirectory[] =
- FILE_PATH_LITERAL("ChromeRecovery");
- // The hard-coded Recovery executable. This file comes from the CRX, and we
- // create an elevated process from it.
- constexpr base::FilePath::CharType kRecoveryExeName[] =
- FILE_PATH_LITERAL("ChromeRecovery.exe");
- // The hard-coded SHA256 of the SubjectPublicKeyInfo used to sign the Recovery
- // CRX which contains ChromeRecovery.exe.
- std::vector<uint8_t> GetRecoveryCRXHash() {
- return std::vector<uint8_t>{0x5f, 0x94, 0xe0, 0x3c, 0x64, 0x30, 0x9f, 0xbc,
- 0xfe, 0x00, 0x9a, 0x27, 0x3e, 0x52, 0xbf, 0xa5,
- 0x84, 0xb9, 0xb3, 0x75, 0x07, 0x29, 0xde, 0xfa,
- 0x32, 0x76, 0xd9, 0x93, 0xb5, 0xa3, 0xce, 0x02};
- }
- // This function is only meant to be called when a Windows API function errors
- // out, and the corresponding ::GetLastResult is expected to be set to an error.
- // There could be cases where ::GetLastError() is not set correctly, this
- // function returns E_FAIL in those cases.
- HRESULT HRESULTFromLastError() {
- const auto error_code = ::GetLastError();
- return (error_code != ERROR_SUCCESS) ? HRESULT_FROM_WIN32(error_code)
- : E_FAIL;
- }
- // Opens and returns the COM caller's |process| given the process id, or the
- // current process if |proc_id| is 0.
- HRESULT OpenCallingProcess(uint32_t proc_id, base::Process* process) {
- DCHECK(proc_id);
- DCHECK(process);
- HRESULT hr = ::CoImpersonateClient();
- if (FAILED(hr))
- return hr;
- base::ScopedClosureRunner revert_to_self(
- base::BindOnce([]() { ::CoRevertToSelf(); }));
- *process = base::Process::OpenWithAccess(proc_id, PROCESS_DUP_HANDLE);
- return process->IsValid() ? S_OK : HRESULTFromLastError();
- }
- // Opens and returns a base::File instance for the |file_path|. We impersonate
- // the COM caller when opening the base::File instance. This is to ensure that
- // the COM caller has access to the file.
- HRESULT OpenFileImpersonated(const base::FilePath& file_path,
- int flags,
- base::File* file) {
- DCHECK(file);
- HRESULT hr = ::CoImpersonateClient();
- if (FAILED(hr))
- return hr;
- base::ScopedClosureRunner revert_to_self(
- base::BindOnce([]() { ::CoRevertToSelf(); }));
- file->Initialize(file_path, flags);
- if (!file->IsValid())
- return HRESULTFromLastError();
- if (::GetFileType(file->GetPlatformFile()) != FILE_TYPE_DISK)
- return E_INVALIDARG;
- int64_t from_length = file->GetLength();
- return from_length > 0 && from_length < kMaxFileSize ? S_OK : E_INVALIDARG;
- }
- // Opens |from| while impersonating the COM caller, and then copies the contents
- // of |from| to |to|. |from| is opened impersonated to ensure that the COM
- // caller has access to the file.
- HRESULT CopyFileImpersonated(const base::FilePath from,
- const base::FilePath& to) {
- base::File from_file;
- HRESULT hr =
- OpenFileImpersonated(from,
- base::File::FLAG_READ | base::File::FLAG_OPEN |
- base::File::FLAG_WIN_SEQUENTIAL_SCAN,
- &from_file);
- if (FAILED(hr))
- return hr;
- base::File to_file;
- to_file.Initialize(to, base::File::FLAG_WRITE |
- base::File::FLAG_CREATE_ALWAYS |
- base::File::FLAG_WIN_SEQUENTIAL_SCAN);
- if (!to_file.IsValid())
- return HRESULTFromLastError();
- constexpr size_t kBufferSize = 0x10000;
- std::vector<char> buffer(kBufferSize);
- for (uint64_t total_bytes_read = 0;;) {
- const int bytes_read =
- from_file.ReadAtCurrentPos(buffer.data(), buffer.size());
- if (bytes_read < 0)
- return HRESULTFromLastError();
- if (bytes_read == 0)
- return S_OK;
- total_bytes_read += bytes_read;
- if (total_bytes_read > kMaxFileSize)
- return E_INVALIDARG;
- const int bytes_written = to_file.WriteAtCurrentPos(&buffer[0], bytes_read);
- if (bytes_written < 0)
- return HRESULTFromLastError();
- if (bytes_written != bytes_read)
- return E_UNEXPECTED;
- }
- NOTREACHED();
- return S_OK;
- }
- // Validates the provided CRX using the |crx_hash|, and if validation succeeds,
- // unpacks the CRX under |unpack_under_path|. Returns the unpacked CRX
- // directory in |unpacked_crx_dir|.
- HRESULT ValidateAndUnpackCRX(const base::FilePath& from_crx_path,
- const crx_file::VerifierFormat& crx_format,
- const std::vector<uint8_t>& crx_hash,
- const base::FilePath& unpack_under_path,
- base::ScopedTempDir* unpacked_crx_dir) {
- DCHECK(unpacked_crx_dir);
- base::ScopedTempDir to_dir;
- if (!to_dir.CreateUniqueTempDirUnderPath(unpack_under_path))
- return HRESULTFromLastError();
- const base::FilePath to_crx_path = to_dir.GetPath().Append(kCRXFileName);
- // Copy |from_crx_path| impersonated. This is to prevent us from copying files
- // that may not be accessible to the calling COM user.
- HRESULT hr = CopyFileImpersonated(from_crx_path, to_crx_path);
- if (FAILED(hr))
- return hr;
- std::string public_key;
- if (crx_file::Verify(to_crx_path, crx_format, {crx_hash}, {}, &public_key,
- nullptr, /*compressed_verified_contents=*/nullptr) !=
- crx_file::VerifierResult::OK_FULL) {
- return CRYPT_E_NO_MATCH;
- }
- if (!zip::Unzip(to_crx_path, to_dir.GetPath()))
- return E_UNEXPECTED;
- LOG_IF(WARNING, !base::DeleteFile(to_crx_path));
- LOG_IF(WARNING, !unpacked_crx_dir->Set(to_dir.Take()));
- return S_OK;
- }
- // Runs the executable |path_and_name| with the provided |args|. The returned
- // |proc_handle| is a process handle that is valid for the |calling_process|
- // process.
- HRESULT LaunchCmd(const base::CommandLine& command_line,
- const base::Process& calling_process,
- base::win::ScopedHandle* proc_handle) {
- DCHECK(!command_line.GetCommandLineString().empty());
- DCHECK(proc_handle);
- base::LaunchOptions options = {};
- options.feedback_cursor_off = true;
- base::GetTempDir(&options.current_directory);
- base::Process proc = base::LaunchProcess(command_line, options);
- if (!proc.IsValid())
- return HRESULTFromLastError();
- HANDLE duplicate_proc_handle = nullptr;
- constexpr DWORD desired_access =
- PROCESS_QUERY_LIMITED_INFORMATION | SYNCHRONIZE;
- bool res = ::DuplicateHandle(
- ::GetCurrentProcess(), // Current process.
- proc.Handle(), // Process handle to duplicate.
- calling_process.Handle(), // Process receiving the handle.
- &duplicate_proc_handle, // Duplicated handle.
- desired_access, // Access requested for the new handle.
- FALSE, // Don't inherit the new handle.
- 0) != 0;
- if (!res)
- return HRESULTFromLastError();
- proc_handle->Set(duplicate_proc_handle);
- return S_OK;
- }
- HRESULT ValidateCRXArgs(const std::wstring& browser_appid,
- const std::wstring& browser_version,
- const std::wstring& session_id) {
- if (!browser_appid.empty()) {
- GUID guid = {};
- HRESULT hr = ::IIDFromString(browser_appid.c_str(), &guid);
- if (FAILED(hr))
- return hr;
- }
- const base::Version version(base::WideToASCII(browser_version));
- if (!version.IsValid())
- return E_INVALIDARG;
- GUID session_guid = {};
- return ::IIDFromString(session_id.c_str(), &session_guid);
- }
- // Deletes all the files and subdirectories within |directory_path|. Errors are
- // ignored.
- void DeleteDirectoryFiles(const base::FilePath& directory_path) {
- base::FileEnumerator file_enum(
- directory_path, false,
- base::FileEnumerator::FILES | base::FileEnumerator::DIRECTORIES);
- for (base::FilePath current = file_enum.Next(); !current.empty();
- current = file_enum.Next()) {
- base::DeletePathRecursively(current);
- }
- }
- // Schedules deletion after reboot of |dir_name| as well as all the files and
- // subdirectories within |dir_name|. Errors are ignored.
- void ScheduleDirectoryForDeletion(const base::FilePath& dir_name) {
- // First schedule all the files within |dir_name| for deletion.
- base::FileEnumerator file_enum(dir_name, false, base::FileEnumerator::FILES);
- for (base::FilePath file = file_enum.Next(); !file.empty();
- file = file_enum.Next()) {
- base::DeleteFileAfterReboot(file);
- }
- // Then recurse to all the subdirectories.
- base::FileEnumerator dir_enum(dir_name, false,
- base::FileEnumerator::DIRECTORIES);
- for (base::FilePath sub_dir = dir_enum.Next(); !sub_dir.empty();
- sub_dir = dir_enum.Next()) {
- ScheduleDirectoryForDeletion(sub_dir);
- }
- // Now schedule the empty directory itself.
- base::DeleteFileAfterReboot(dir_name);
- }
- // Returns the ChromeRecovery directory under Google\Chrome. For machine
- // installs, this directory is under %ProgramFiles%, which is writeable only by
- // adminstrators. We use this secure directory to validate and unpack the CRX to
- // prevent tampering.
- HRESULT GetChromeRecoveryDirectory(base::FilePath* dir) {
- base::FilePath recovery_dir;
- if (!base::PathService::Get(base::DIR_EXE, &recovery_dir))
- return HRESULTFromLastError();
- recovery_dir = recovery_dir.DirName().DirName().Append(kRecoveryDirectory);
- *dir = std::move(recovery_dir);
- return S_OK;
- }
- } // namespace
- HRESULT CleanupChromeRecoveryDirectory() {
- base::FilePath recovery_dir;
- HRESULT hr = GetChromeRecoveryDirectory(&recovery_dir);
- if (FAILED(hr))
- return hr;
- DeleteDirectoryFiles(recovery_dir);
- return S_OK;
- }
- HRESULT RunChromeRecoveryCRX(const base::FilePath& crx_path,
- const std::wstring& browser_appid,
- const std::wstring& browser_version,
- const std::wstring& session_id,
- uint32_t caller_proc_id,
- base::win::ScopedHandle* proc_handle) {
- if (crx_path.empty() || !caller_proc_id || !proc_handle)
- return E_INVALIDARG;
- HRESULT hr = ValidateCRXArgs(browser_appid, browser_version, session_id);
- if (FAILED(hr))
- return hr;
- base::CommandLine args(base::CommandLine::NO_PROGRAM);
- if (!browser_appid.empty())
- args.AppendSwitchNative("appguid", browser_appid);
- args.AppendSwitchNative("browser-version", browser_version);
- args.AppendSwitchNative("sessionid", session_id);
- args.AppendSwitch("system");
- base::FilePath unpack_dir;
- hr = GetChromeRecoveryDirectory(&unpack_dir);
- if (FAILED(hr))
- return hr;
- return RunCRX(crx_path, args,
- crx_file::VerifierFormat::CRX3_WITH_PUBLISHER_PROOF,
- GetRecoveryCRXHash(), unpack_dir,
- base::FilePath(kRecoveryExeName), caller_proc_id, proc_handle);
- }
- HRESULT RunCRX(const base::FilePath& crx_path,
- const base::CommandLine& args,
- const crx_file::VerifierFormat& crx_format,
- const std::vector<uint8_t>& crx_hash,
- const base::FilePath& unpack_under_path,
- const base::FilePath& exe_filename,
- uint32_t caller_proc_id,
- base::win::ScopedHandle* proc_handle) {
- DCHECK(!crx_path.empty());
- DCHECK(!crx_hash.empty());
- DCHECK(!unpack_under_path.empty());
- DCHECK(!exe_filename.empty());
- DCHECK(caller_proc_id);
- DCHECK(proc_handle);
- base::Process calling_process;
- HRESULT hr = OpenCallingProcess(caller_proc_id, &calling_process);
- if (FAILED(hr))
- return hr;
- base::ScopedTempDir unpacked_crx_dir;
- hr = ValidateAndUnpackCRX(crx_path, crx_format, crx_hash, unpack_under_path,
- &unpacked_crx_dir);
- if (FAILED(hr))
- return hr;
- const base::FilePath path_and_name =
- unpacked_crx_dir.GetPath().Append(exe_filename);
- base::CommandLine command_line(path_and_name);
- command_line.AppendArguments(args, false);
- base::win::ScopedHandle scoped_proc_handle;
- hr = LaunchCmd(command_line, calling_process, &scoped_proc_handle);
- if (FAILED(hr))
- return hr;
- ScheduleDirectoryForDeletion(unpacked_crx_dir.Take());
- *proc_handle = std::move(scoped_proc_handle);
- return hr;
- }
- } // namespace elevation_service
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