root/remoting/host/win/wts_session_process_delegate.cc

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DEFINITIONS

This source file includes following definitions.
  1. Initialize
  2. Stop
  3. LaunchProcess
  4. Send
  5. CloseChannel
  6. KillProcess
  7. OnIOCompleted
  8. OnMessageReceived
  9. OnChannelConnected
  10. OnChannelError
  11. DoLaunchProcess
  12. DrainJobNotifications
  13. DrainJobNotificationsCompleted
  14. InitializeJob
  15. InitializeJobCompleted
  16. OnActiveProcessZero
  17. ReportFatalError
  18. ReportProcessLaunched
  19. Initialize
  20. LaunchProcess
  21. Send
  22. CloseChannel
  23. KillProcess

// Copyright (c) 2012 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.
//
// This file implements the Windows service controlling Me2Me host processes
// running within user sessions.

#include "remoting/host/win/wts_session_process_delegate.h"

#include "base/bind.h"
#include "base/command_line.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/message_loop/message_loop.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/utf_string_conversions.h"
#include "base/thread_task_runner_handle.h"
#include "base/win/scoped_handle.h"
#include "base/win/windows_version.h"
#include "ipc/ipc_channel.h"
#include "ipc/ipc_channel_proxy.h"
#include "ipc/ipc_listener.h"
#include "ipc/ipc_message.h"
#include "remoting/host/host_main.h"
#include "remoting/host/ipc_constants.h"
#include "remoting/host/ipc_util.h"
#include "remoting/host/win/launch_process_with_token.h"
#include "remoting/host/win/worker_process_launcher.h"
#include "remoting/host/win/wts_terminal_monitor.h"
#include "remoting/host/worker_process_ipc_delegate.h"

using base::win::ScopedHandle;

// Name of the default session desktop.
const char kDefaultDesktopName[] = "winsta0\\default";

namespace remoting {

// A private class actually implementing the functionality provided by
// |WtsSessionProcessDelegate|. This class is ref-counted and implements
// asynchronous fire-and-forget shutdown.
class WtsSessionProcessDelegate::Core
    : public base::RefCountedThreadSafe<Core>,
      public base::MessagePumpForIO::IOHandler,
      public IPC::Listener {
 public:
  Core(scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
       scoped_ptr<CommandLine> target,
       bool launch_elevated,
       const std::string& channel_security);

  // Initializes the object returning true on success.
  bool Initialize(uint32 session_id);

  // Stops the object asynchronously.
  void Stop();

  // Mirrors WorkerProcessLauncher::Delegate.
  void LaunchProcess(WorkerProcessLauncher* event_handler);
  void Send(IPC::Message* message);
  void CloseChannel();
  void KillProcess();

 private:
  friend class base::RefCountedThreadSafe<Core>;
  virtual ~Core();

  // base::MessagePumpForIO::IOHandler implementation.
  virtual void OnIOCompleted(base::MessagePumpForIO::IOContext* context,
                             DWORD bytes_transferred,
                             DWORD error) OVERRIDE;

  // IPC::Listener implementation.
  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
  virtual void OnChannelConnected(int32 peer_pid) OVERRIDE;
  virtual void OnChannelError() OVERRIDE;

  // The actual implementation of LaunchProcess()
  void DoLaunchProcess();

  // Drains the completion port queue to make sure that all job object
  // notifications have been received.
  void DrainJobNotifications();

  // Notified that the completion port queue has been drained.
  void DrainJobNotificationsCompleted();

  // Creates and initializes the job object that will sandbox the launched child
  // processes.
  void InitializeJob(scoped_ptr<base::win::ScopedHandle> job);

  // Notified that the job object initialization is complete.
  void InitializeJobCompleted(scoped_ptr<base::win::ScopedHandle> job);

  // Called when the number of processes running in the job reaches zero.
  void OnActiveProcessZero();

  void ReportFatalError();
  void ReportProcessLaunched(base::win::ScopedHandle worker_process);

  // The task runner all public methods of this class should be called on.
  scoped_refptr<base::SingleThreadTaskRunner> caller_task_runner_;

  // The task runner serving job object notifications.
  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;

  // The server end of the IPC channel used to communicate to the worker
  // process.
  scoped_ptr<IPC::ChannelProxy> channel_;

  // Security descriptor (as SDDL) to be applied to |channel_|.
  std::string channel_security_;

  WorkerProcessLauncher* event_handler_;

  // Pointer to GetNamedPipeClientProcessId() API if it is available.
  typedef BOOL (WINAPI * GetNamedPipeClientProcessIdFn)(HANDLE, DWORD*);
  GetNamedPipeClientProcessIdFn get_named_pipe_client_pid_;

  // The job object used to control the lifetime of child processes.
  base::win::ScopedHandle job_;

  // True if the worker process should be launched elevated.
  bool launch_elevated_;

  // True if a laucnh attemp is pending.
  bool launch_pending_;

  // The named pipe used as the transport by |channel_|.
  base::win::ScopedHandle pipe_;

  // The token to be used to launch a process in a different session.
  base::win::ScopedHandle session_token_;

  // Command line of the launched process.
  scoped_ptr<CommandLine> target_command_;

  // The handle of the worker process, if launched.
  base::win::ScopedHandle worker_process_;

  DISALLOW_COPY_AND_ASSIGN(Core);
};

WtsSessionProcessDelegate::Core::Core(
    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
    scoped_ptr<CommandLine> target_command,
    bool launch_elevated,
    const std::string& channel_security)
    : caller_task_runner_(base::ThreadTaskRunnerHandle::Get()),
      io_task_runner_(io_task_runner),
      channel_security_(channel_security),
      event_handler_(NULL),
      get_named_pipe_client_pid_(NULL),
      launch_elevated_(launch_elevated),
      launch_pending_(false),
      target_command_(target_command.Pass()) {
}

bool WtsSessionProcessDelegate::Core::Initialize(uint32 session_id) {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  // Windows XP does not support elevation.
  if (base::win::GetVersion() < base::win::VERSION_VISTA)
    launch_elevated_ = false;

  if (launch_elevated_) {
    // GetNamedPipeClientProcessId() is available starting from Vista.
    HMODULE kernel32 = ::GetModuleHandle(L"kernel32.dll");
    CHECK(kernel32 != NULL);

    get_named_pipe_client_pid_ =
        reinterpret_cast<GetNamedPipeClientProcessIdFn>(
            GetProcAddress(kernel32, "GetNamedPipeClientProcessId"));
    CHECK(get_named_pipe_client_pid_ != NULL);

    ScopedHandle job;
    job.Set(CreateJobObject(NULL, NULL));
    if (!job.IsValid()) {
      LOG_GETLASTERROR(ERROR) << "Failed to create a job object";
      return false;
    }

    // Limit the number of active processes in the job to two (the helper
    // process performing elevation and the worker process itself) and make sure
    // that all processes will be killed once the job object is destroyed.
    JOBOBJECT_EXTENDED_LIMIT_INFORMATION info;
    memset(&info, 0, sizeof(info));
    info.BasicLimitInformation.LimitFlags = JOB_OBJECT_LIMIT_ACTIVE_PROCESS |
        JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE;
    info.BasicLimitInformation.ActiveProcessLimit = 2;
    if (!SetInformationJobObject(job,
                                 JobObjectExtendedLimitInformation,
                                 &info,
                                 sizeof(info))) {
      LOG_GETLASTERROR(ERROR) << "Failed to set limits on the job object";
      return false;
    }

    // ScopedHandle is not compatible with base::Passed, so we wrap it to
    // a scoped pointer.
    scoped_ptr<ScopedHandle> job_wrapper(new ScopedHandle());
    *job_wrapper = job.Pass();

    // To receive job object notifications the job object is registered with
    // the completion port represented by |io_task_runner|. The registration has
    // to be done on the I/O thread because
    // MessageLoopForIO::RegisterJobObject() can only be called via
    // MessageLoopForIO::current().
    io_task_runner_->PostTask(
        FROM_HERE,
        base::Bind(&Core::InitializeJob, this, base::Passed(&job_wrapper)));
  }

  // Create a session token for the launched process.
  return CreateSessionToken(session_id, &session_token_);
}

void WtsSessionProcessDelegate::Core::Stop() {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  KillProcess();

  // Drain the completion queue to make sure all job object notifications have
  // been received.
  DrainJobNotificationsCompleted();
}

void WtsSessionProcessDelegate::Core::LaunchProcess(
    WorkerProcessLauncher* event_handler) {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());
  DCHECK(!event_handler_);

  event_handler_ = event_handler;
  DoLaunchProcess();
}

void WtsSessionProcessDelegate::Core::Send(IPC::Message* message) {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  if (channel_) {
    channel_->Send(message);
  } else {
    delete message;
  }
}

void WtsSessionProcessDelegate::Core::CloseChannel() {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  channel_.reset();
  pipe_.Close();
}

void WtsSessionProcessDelegate::Core::KillProcess() {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  channel_.reset();
  event_handler_ = NULL;
  launch_pending_ = false;
  pipe_.Close();

  if (launch_elevated_) {
    if (job_.IsValid())
      TerminateJobObject(job_, CONTROL_C_EXIT);
  } else {
    if (worker_process_.IsValid())
      TerminateProcess(worker_process_, CONTROL_C_EXIT);
  }

  worker_process_.Close();
}

WtsSessionProcessDelegate::Core::~Core() {
  DCHECK(!channel_);
  DCHECK(!event_handler_);
  DCHECK(!pipe_.IsValid());
  DCHECK(!worker_process_.IsValid());
}

void WtsSessionProcessDelegate::Core::OnIOCompleted(
    base::MessagePumpForIO::IOContext* context,
    DWORD bytes_transferred,
    DWORD error) {
  DCHECK(io_task_runner_->BelongsToCurrentThread());

  // |bytes_transferred| is used in job object notifications to supply
  // the message ID; |context| carries process ID.
  if (bytes_transferred == JOB_OBJECT_MSG_ACTIVE_PROCESS_ZERO) {
    caller_task_runner_->PostTask(FROM_HERE,
                                  base::Bind(&Core::OnActiveProcessZero, this));
  }
}

bool WtsSessionProcessDelegate::Core::OnMessageReceived(
    const IPC::Message& message) {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  return event_handler_->OnMessageReceived(message);
}

void WtsSessionProcessDelegate::Core::OnChannelConnected(int32 peer_pid) {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  // Report the worker PID now if the worker process is launched indirectly.
  // Note that in this case the pipe's security descriptor is the only
  // protection against a malicious processed connecting to the pipe.
  if (launch_elevated_) {
    DWORD pid;
    if (!get_named_pipe_client_pid_(pipe_, &pid)) {
      LOG_GETLASTERROR(ERROR) << "Failed to retrive PID of the client";
      ReportFatalError();
      return;
    }

    if (pid != static_cast<DWORD>(peer_pid)) {
      LOG(ERROR) << "The actual client PID " << pid
                 << " does not match the one reported by the client: "
                 << peer_pid;
      ReportFatalError();
      return;
    }

    DWORD desired_access =
        SYNCHRONIZE | PROCESS_DUP_HANDLE | PROCESS_QUERY_INFORMATION;
    ScopedHandle worker_process(OpenProcess(desired_access, false, pid));
    if (!worker_process.IsValid()) {
      LOG_GETLASTERROR(ERROR) << "Failed to open process " << pid;
      ReportFatalError();
      return;
    }

    ReportProcessLaunched(worker_process.Pass());
  }

  if (event_handler_)
    event_handler_->OnChannelConnected(peer_pid);
}

void WtsSessionProcessDelegate::Core::OnChannelError() {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  event_handler_->OnChannelError();
}

void WtsSessionProcessDelegate::Core::DoLaunchProcess() {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());
  DCHECK(!channel_);
  DCHECK(!pipe_.IsValid());
  DCHECK(!worker_process_.IsValid());

  CommandLine command_line(target_command_->argv());
  if (launch_elevated_) {
    // The job object is not ready. Retry starting the host process later.
    if (!job_.IsValid()) {
      launch_pending_ = true;
      return;
    }

    // Construct the helper binary name.
    base::FilePath helper_binary;
    if (!GetInstalledBinaryPath(kHostBinaryName, &helper_binary)) {
      ReportFatalError();
      return;
    }

    // Create the command line passing the name of the IPC channel to use and
    // copying known switches from the caller's command line.
    command_line.SetProgram(helper_binary);
    command_line.AppendSwitchPath(kElevateSwitchName,
                                  target_command_->GetProgram());
  }

  // Create the server end of the IPC channel.
  std::string channel_name = IPC::Channel::GenerateUniqueRandomChannelID();
  ScopedHandle pipe;
  if (!CreateIpcChannel(channel_name, channel_security_, &pipe)) {
    ReportFatalError();
    return;
  }

  // Wrap the pipe into an IPC channel.
  scoped_ptr<IPC::ChannelProxy> channel(new IPC::ChannelProxy(
      IPC::ChannelHandle(pipe),
      IPC::Channel::MODE_SERVER,
      this,
      io_task_runner_));

  // Pass the name of the IPC channel to use.
  command_line.AppendSwitchNative(kDaemonPipeSwitchName,
                                  base::UTF8ToWide(channel_name));

  // Try to launch the process.
  ScopedHandle worker_process;
  ScopedHandle worker_thread;
  if (!LaunchProcessWithToken(command_line.GetProgram(),
                              command_line.GetCommandLineString(),
                              session_token_,
                              NULL,
                              NULL,
                              false,
                              CREATE_SUSPENDED | CREATE_BREAKAWAY_FROM_JOB,
                              base::UTF8ToUTF16(kDefaultDesktopName).c_str(),
                              &worker_process,
                              &worker_thread)) {
    ReportFatalError();
    return;
  }

  if (launch_elevated_) {
    if (!AssignProcessToJobObject(job_, worker_process)) {
      LOG_GETLASTERROR(ERROR)
          << "Failed to assign the worker to the job object";
      ReportFatalError();
      return;
    }
  }

  if (!ResumeThread(worker_thread)) {
    LOG_GETLASTERROR(ERROR) << "Failed to resume the worker thread";
    ReportFatalError();
    return;
  }

  channel_ = channel.Pass();
  pipe_ = pipe.Pass();

  // Report success if the worker process is lauched directly. Otherwise, PID of
  // the client connected to the pipe will be used later. See
  // OnChannelConnected().
  if (!launch_elevated_)
    ReportProcessLaunched(worker_process.Pass());
}

void WtsSessionProcessDelegate::Core::DrainJobNotifications() {
  DCHECK(io_task_runner_->BelongsToCurrentThread());

  // DrainJobNotifications() is posted after the job object is destroyed, so
  // by this time all notifications from the job object have been processed
  // already. Let the main thread know that the queue has been drained.
  caller_task_runner_->PostTask(FROM_HERE, base::Bind(
      &Core::DrainJobNotificationsCompleted, this));
}

void WtsSessionProcessDelegate::Core::DrainJobNotificationsCompleted() {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  if (job_.IsValid()) {
    job_.Close();

    // Drain the completion queue to make sure all job object notification have
    // been received.
    io_task_runner_->PostTask(FROM_HERE, base::Bind(
        &Core::DrainJobNotifications, this));
  }
}

void WtsSessionProcessDelegate::Core::InitializeJob(
    scoped_ptr<base::win::ScopedHandle> job) {
  DCHECK(io_task_runner_->BelongsToCurrentThread());

  // Register to receive job notifications via the I/O thread's completion port.
  if (!base::MessageLoopForIO::current()->RegisterJobObject(job->Get(), this)) {
    LOG_GETLASTERROR(ERROR)
        << "Failed to associate the job object with a completion port";
    return;
  }

  // Let the main thread know that initialization is complete.
  caller_task_runner_->PostTask(FROM_HERE, base::Bind(
      &Core::InitializeJobCompleted, this, base::Passed(&job)));
}

void WtsSessionProcessDelegate::Core::InitializeJobCompleted(
    scoped_ptr<ScopedHandle> job) {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());
  DCHECK(!job_.IsValid());

  job_ = job->Pass();

  if (launch_pending_)
    DoLaunchProcess();
}

void WtsSessionProcessDelegate::Core::OnActiveProcessZero() {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  if (launch_pending_) {
    LOG(ERROR) << "The worker process exited before connecting via IPC.";
    launch_pending_ = false;
    ReportFatalError();
  }
}

void WtsSessionProcessDelegate::Core::ReportFatalError() {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());

  channel_.reset();
  pipe_.Close();

  WorkerProcessLauncher* event_handler = event_handler_;
  event_handler_ = NULL;
  event_handler->OnFatalError();
}

void WtsSessionProcessDelegate::Core::ReportProcessLaunched(
    base::win::ScopedHandle worker_process) {
  DCHECK(caller_task_runner_->BelongsToCurrentThread());
  DCHECK(!worker_process_.IsValid());

  worker_process_ = worker_process.Pass();

  // Report a handle that can be used to wait for the worker process completion,
  // query information about the process and duplicate handles.
  DWORD desired_access =
      SYNCHRONIZE | PROCESS_DUP_HANDLE | PROCESS_QUERY_INFORMATION;
  HANDLE temp_handle;
  if (!DuplicateHandle(GetCurrentProcess(),
                       worker_process_,
                       GetCurrentProcess(),
                       &temp_handle,
                       desired_access,
                       FALSE,
                       0)) {
    LOG_GETLASTERROR(ERROR) << "Failed to duplicate a handle";
    ReportFatalError();
    return;
  }
  ScopedHandle limited_handle(temp_handle);

  event_handler_->OnProcessLaunched(limited_handle.Pass());
}

WtsSessionProcessDelegate::WtsSessionProcessDelegate(
    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
    scoped_ptr<CommandLine> target_command,
    bool launch_elevated,
    const std::string& channel_security) {
  core_ = new Core(io_task_runner,
                   target_command.Pass(),
                   launch_elevated,
                   channel_security);
}

WtsSessionProcessDelegate::~WtsSessionProcessDelegate() {
  core_->Stop();
}

bool WtsSessionProcessDelegate::Initialize(uint32 session_id) {
  return core_->Initialize(session_id);
}

void WtsSessionProcessDelegate::LaunchProcess(
    WorkerProcessLauncher* event_handler) {
  core_->LaunchProcess(event_handler);
}

void WtsSessionProcessDelegate::Send(IPC::Message* message) {
  core_->Send(message);
}

void WtsSessionProcessDelegate::CloseChannel() {
  core_->CloseChannel();
}

void WtsSessionProcessDelegate::KillProcess() {
  core_->KillProcess();
}

} // namespace remoting

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