components/proximity_auth/unlock_manager.cc

// Copyright 2015 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 "components/proximity_auth/unlock_manager.h"

#include "base/bind.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/time/default_tick_clock.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "components/proximity_auth/logging/logging.h"
#include "components/proximity_auth/messenger.h"
#include "components/proximity_auth/metrics.h"
#include "components/proximity_auth/proximity_auth_client.h"
#include "components/proximity_auth/proximity_monitor_impl.h"
#include "components/proximity_auth/remote_device.h"
#include "components/proximity_auth/secure_context.h"
#include "device/bluetooth/bluetooth_adapter_factory.h"

#if defined(OS_CHROMEOS)
#include "chromeos/dbus/dbus_thread_manager.h"

using chromeos::DBusThreadManager;
#endif  // defined(OS_CHROMEOS)

namespace proximity_auth {
namespace {

// The maximum amount of time, in seconds, that the unlock manager can stay in
// the 'waking up' state after resuming from sleep.
const int kWakingUpDurationSecs = 15;

// The limit, in seconds, on the elapsed time for an auth attempt. If an auth
// attempt exceeds this limit, it will time out and be rejected. This is
// provided as a failsafe, in case something goes wrong.
const int kAuthAttemptTimeoutSecs = 5;

// Returns the remote device's security settings state, for metrics,
// corresponding to a remote status update.
metrics::RemoteSecuritySettingsState GetRemoteSecuritySettingsState(
    const RemoteStatusUpdate& status_update) {
  switch (status_update.secure_screen_lock_state) {
    case SECURE_SCREEN_LOCK_STATE_UNKNOWN:
      return metrics::RemoteSecuritySettingsState::UNKNOWN;

    case SECURE_SCREEN_LOCK_DISABLED:
      switch (status_update.trust_agent_state) {
        case TRUST_AGENT_UNSUPPORTED:
          return metrics::RemoteSecuritySettingsState::
              SCREEN_LOCK_DISABLED_TRUST_AGENT_UNSUPPORTED;
        case TRUST_AGENT_DISABLED:
          return metrics::RemoteSecuritySettingsState::
              SCREEN_LOCK_DISABLED_TRUST_AGENT_DISABLED;
        case TRUST_AGENT_ENABLED:
          return metrics::RemoteSecuritySettingsState::
              SCREEN_LOCK_DISABLED_TRUST_AGENT_ENABLED;
      }

    case SECURE_SCREEN_LOCK_ENABLED:
      switch (status_update.trust_agent_state) {
        case TRUST_AGENT_UNSUPPORTED:
          return metrics::RemoteSecuritySettingsState::
              SCREEN_LOCK_ENABLED_TRUST_AGENT_UNSUPPORTED;
        case TRUST_AGENT_DISABLED:
          return metrics::RemoteSecuritySettingsState::
              SCREEN_LOCK_ENABLED_TRUST_AGENT_DISABLED;
        case TRUST_AGENT_ENABLED:
          return metrics::RemoteSecuritySettingsState::
              SCREEN_LOCK_ENABLED_TRUST_AGENT_ENABLED;
      }
  }

  NOTREACHED();
  return metrics::RemoteSecuritySettingsState::UNKNOWN;
}

}  // namespace

UnlockManager::UnlockManager(
    ProximityAuthSystem::ScreenlockType screenlock_type,
    ProximityAuthClient* proximity_auth_client)
    : screenlock_type_(screenlock_type),
      life_cycle_(nullptr),
      proximity_auth_client_(proximity_auth_client),
      is_locked_(false),
      is_attempting_auth_(false),
      is_waking_up_(false),
      screenlock_state_(ScreenlockState::INACTIVE),
      clear_waking_up_state_weak_ptr_factory_(this),
      reject_auth_attempt_weak_ptr_factory_(this),
      weak_ptr_factory_(this) {
  ScreenlockBridge* screenlock_bridge = ScreenlockBridge::Get();
  screenlock_bridge->AddObserver(this);
  OnScreenLockedOrUnlocked(screenlock_bridge->IsLocked());

#if defined(OS_CHROMEOS)
  DBusThreadManager::Get()->GetPowerManagerClient()->AddObserver(this);
#endif  // defined(OS_CHROMEOS)
  SetWakingUpState(true);

  if (device::BluetoothAdapterFactory::IsBluetoothAdapterAvailable()) {
    device::BluetoothAdapterFactory::GetAdapter(
        base::Bind(&UnlockManager::OnBluetoothAdapterInitialized,
                   weak_ptr_factory_.GetWeakPtr()));
  }
}

UnlockManager::~UnlockManager() {
  if (GetMessenger())
    GetMessenger()->RemoveObserver(this);

  ScreenlockBridge::Get()->RemoveObserver(this);

#if defined(OS_CHROMEOS)
  DBusThreadManager::Get()->GetPowerManagerClient()->RemoveObserver(this);
#endif  // defined(OS_CHROMEOS)

  if (bluetooth_adapter_)
    bluetooth_adapter_->RemoveObserver(this);
}

bool UnlockManager::IsUnlockAllowed() {
  return (remote_screenlock_state_ &&
          *remote_screenlock_state_ == RemoteScreenlockState::UNLOCKED &&
          life_cycle_ &&
          life_cycle_->GetState() ==
              RemoteDeviceLifeCycle::State::SECURE_CHANNEL_ESTABLISHED &&
          proximity_monitor_ && proximity_monitor_->IsUnlockAllowed() &&
          (screenlock_type_ != ProximityAuthSystem::SIGN_IN ||
           (GetMessenger() && GetMessenger()->SupportsSignIn())));
}

void UnlockManager::SetRemoteDeviceLifeCycle(
    RemoteDeviceLifeCycle* life_cycle) {
  if (GetMessenger())
    GetMessenger()->RemoveObserver(this);

  life_cycle_ = life_cycle;
  if (life_cycle_) {
    proximity_monitor_ = CreateProximityMonitor(life_cycle->GetRemoteDevice());
    SetWakingUpState(true);
  } else {
    proximity_monitor_.reset();
  }

  UpdateLockScreen();
}

void UnlockManager::OnLifeCycleStateChanged() {
  RemoteDeviceLifeCycle::State state = life_cycle_->GetState();
  PA_LOG(INFO) << "[Unlock] RemoteDeviceLifeCycle state changed: "
               << static_cast<int>(state);

  remote_screenlock_state_.reset();
  if (state == RemoteDeviceLifeCycle::State::SECURE_CHANNEL_ESTABLISHED)
    GetMessenger()->AddObserver(this);

  if (state == RemoteDeviceLifeCycle::State::AUTHENTICATION_FAILED)
    SetWakingUpState(false);

  UpdateLockScreen();
}

void UnlockManager::OnUnlockEventSent(bool success) {
  if (!is_attempting_auth_) {
    PA_LOG(ERROR) << "[Unlock] Sent easy_unlock event, but no auth attempted.";
    return;
  }

  AcceptAuthAttempt(success);
}

void UnlockManager::OnRemoteStatusUpdate(
    const RemoteStatusUpdate& status_update) {
  PA_LOG(INFO) << "[Unlock] Status Update: ("
               << "user_present=" << status_update.user_presence << ", "
               << "secure_screen_lock="
               << status_update.secure_screen_lock_state << ", "
               << "trust_agent=" << status_update.trust_agent_state << ")";
  metrics::RecordRemoteSecuritySettingsState(
      GetRemoteSecuritySettingsState(status_update));

  remote_screenlock_state_.reset(new RemoteScreenlockState(
      GetScreenlockStateFromRemoteUpdate(status_update)));

  // This also calls |UpdateLockScreen()|
  SetWakingUpState(false);
}

void UnlockManager::OnDecryptResponse(const std::string& decrypted_bytes) {
  if (!is_attempting_auth_) {
    PA_LOG(ERROR) << "[Unlock] Decrypt response received but not attempting "
                  << "auth.";
    return;
  }

  if (decrypted_bytes.empty()) {
    PA_LOG(WARNING) << "[Unlock] Failed to decrypt sign-in challenge.";
    AcceptAuthAttempt(false);
  } else {
    sign_in_secret_.reset(new std::string(decrypted_bytes));
    GetMessenger()->DispatchUnlockEvent();
  }
}

void UnlockManager::OnUnlockResponse(bool success) {
  if (!is_attempting_auth_) {
    PA_LOG(ERROR) << "[Unlock] Unlock response received but not attempting "
                  << "auth.";
    return;
  }

  PA_LOG(INFO) << "[Unlock] Unlock response from remote device: "
               << (success ? "success" : "failure");
  if (success)
    GetMessenger()->DispatchUnlockEvent();
  else
    AcceptAuthAttempt(false);
}

void UnlockManager::OnDisconnected() {
  GetMessenger()->RemoveObserver(this);
}

void UnlockManager::OnScreenDidLock(
    ScreenlockBridge::LockHandler::ScreenType screen_type) {
  OnScreenLockedOrUnlocked(true);
}

void UnlockManager::OnScreenDidUnlock(
    ScreenlockBridge::LockHandler::ScreenType screen_type) {
  OnScreenLockedOrUnlocked(false);
}

void UnlockManager::OnFocusedUserChanged(const AccountId& account_id) {}

void UnlockManager::OnScreenLockedOrUnlocked(bool is_locked) {
  // TODO(tengs): Chrome will only start connecting to the phone when
  // the screen is locked, for privacy reasons. We should reinvestigate
  // this behaviour if we want automatic locking.
  if (is_locked && bluetooth_adapter_ && bluetooth_adapter_->IsPowered() &&
      life_cycle_ &&
      life_cycle_->GetState() ==
          RemoteDeviceLifeCycle::State::FINDING_CONNECTION) {
    SetWakingUpState(true);
  }

  is_locked_ = is_locked;
  UpdateProximityMonitorState();
}

void UnlockManager::OnBluetoothAdapterInitialized(
    scoped_refptr<device::BluetoothAdapter> adapter) {
  bluetooth_adapter_ = adapter;
  bluetooth_adapter_->AddObserver(this);
}

void UnlockManager::AdapterPresentChanged(device::BluetoothAdapter* adapter,
                                          bool present) {
  UpdateLockScreen();
}

void UnlockManager::AdapterPoweredChanged(device::BluetoothAdapter* adapter,
                                          bool powered) {
  UpdateLockScreen();
}

#if defined(OS_CHROMEOS)
void UnlockManager::SuspendDone(const base::TimeDelta& sleep_duration) {
  SetWakingUpState(true);
}
#endif  // defined(OS_CHROMEOS)

void UnlockManager::OnAuthAttempted(
    ScreenlockBridge::LockHandler::AuthType auth_type) {
  if (is_attempting_auth_) {
    PA_LOG(INFO) << "[Unlock] Already attempting auth.";
    return;
  }

  if (auth_type != ScreenlockBridge::LockHandler::USER_CLICK)
    return;

  is_attempting_auth_ = true;

  if (!life_cycle_) {
    PA_LOG(ERROR) << "[Unlock] No life_cycle active when auth is attempted";
    AcceptAuthAttempt(false);
    UpdateLockScreen();
    return;
  }

  if (!IsUnlockAllowed()) {
    AcceptAuthAttempt(false);
    UpdateLockScreen();
    return;
  }

  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
      FROM_HERE,
      base::Bind(&UnlockManager::AcceptAuthAttempt,
                 reject_auth_attempt_weak_ptr_factory_.GetWeakPtr(), false),
      base::TimeDelta::FromSeconds(kAuthAttemptTimeoutSecs));

  if (screenlock_type_ == ProximityAuthSystem::SIGN_IN) {
    SendSignInChallenge();
  } else {
    if (GetMessenger()->SupportsSignIn()) {
      GetMessenger()->RequestUnlock();
    } else {
      PA_LOG(INFO) << "[Unlock] Protocol v3.1 not supported, skipping "
                   << "request_unlock.";
      GetMessenger()->DispatchUnlockEvent();
    }
  }
}

std::unique_ptr<ProximityMonitor> UnlockManager::CreateProximityMonitor(
    const RemoteDevice& remote_device) {
  return base::MakeUnique<ProximityMonitorImpl>(
      remote_device, base::WrapUnique(new base::DefaultTickClock()));
}

void UnlockManager::SendSignInChallenge() {
  if (!life_cycle_ || !GetMessenger() || !GetMessenger()->GetSecureContext()) {
    PA_LOG(ERROR) << "Not ready to send sign-in challenge";
    return;
  }

  RemoteDevice remote_device = life_cycle_->GetRemoteDevice();
  proximity_auth_client_->GetChallengeForUserAndDevice(
      remote_device.user_id, remote_device.public_key,
      GetMessenger()->GetSecureContext()->GetChannelBindingData(),
      base::Bind(&UnlockManager::OnGotSignInChallenge,
                 weak_ptr_factory_.GetWeakPtr()));
}

void UnlockManager::OnGotSignInChallenge(const std::string& challenge) {
  PA_LOG(INFO) << "Got sign-in challenge, sending for decryption...";
  GetMessenger()->RequestDecryption(challenge);
}

ScreenlockState UnlockManager::GetScreenlockState() {
  if (!life_cycle_ ||
      life_cycle_->GetState() == RemoteDeviceLifeCycle::State::STOPPED)
    return ScreenlockState::INACTIVE;

  if (IsUnlockAllowed())
    return ScreenlockState::AUTHENTICATED;

  if (life_cycle_->GetState() ==
      RemoteDeviceLifeCycle::State::AUTHENTICATION_FAILED)
    return ScreenlockState::PHONE_NOT_AUTHENTICATED;

  if (is_waking_up_)
    return ScreenlockState::BLUETOOTH_CONNECTING;

  if (!bluetooth_adapter_ || !bluetooth_adapter_->IsPowered())
    return ScreenlockState::NO_BLUETOOTH;

  Messenger* messenger = GetMessenger();
  if (screenlock_type_ == ProximityAuthSystem::SIGN_IN && messenger &&
      !messenger->SupportsSignIn())
    return ScreenlockState::PHONE_UNSUPPORTED;

  // If the RSSI is too low, then the remote device is nowhere near the local
  // device. This message should take priority over messages about screen lock
  // states.
  if (!proximity_monitor_->IsUnlockAllowed() &&
      !proximity_monitor_->IsInRssiRange())
    return ScreenlockState::RSSI_TOO_LOW;

  if (remote_screenlock_state_) {
    switch (*remote_screenlock_state_) {
      case RemoteScreenlockState::DISABLED:
        return ScreenlockState::PHONE_NOT_LOCKABLE;

      case RemoteScreenlockState::LOCKED:
        if (proximity_monitor_->GetStrategy() ==
                ProximityMonitor::Strategy::CHECK_TRANSMIT_POWER &&
            !proximity_monitor_->IsUnlockAllowed()) {
          return ScreenlockState::PHONE_LOCKED_AND_TX_POWER_TOO_HIGH;
        }
        return ScreenlockState::PHONE_LOCKED;

      case RemoteScreenlockState::UNKNOWN:
        return ScreenlockState::PHONE_UNSUPPORTED;

      case RemoteScreenlockState::UNLOCKED:
        // Handled by the code below.
        break;
    }
  }

  if (!proximity_monitor_->IsUnlockAllowed()) {
    ProximityMonitor::Strategy strategy = proximity_monitor_->GetStrategy();
    if (strategy != ProximityMonitor::Strategy::CHECK_TRANSMIT_POWER) {
      // CHECK_RSSI should have been handled above, and no other states should
      // prevent unlocking.
      PA_LOG(ERROR) << "[Unlock] Invalid ProximityMonitor strategy: "
                    << static_cast<int>(strategy);
      return ScreenlockState::NO_PHONE;
    }
    return ScreenlockState::TX_POWER_TOO_HIGH;
  }

  return ScreenlockState::NO_PHONE;
}

void UnlockManager::UpdateLockScreen() {
  UpdateProximityMonitorState();

  ScreenlockState new_state = GetScreenlockState();
  if (screenlock_state_ == new_state)
    return;

  proximity_auth_client_->UpdateScreenlockState(new_state);
  screenlock_state_ = new_state;
}

void UnlockManager::UpdateProximityMonitorState() {
  if (!proximity_monitor_)
    return;

  if (is_locked_ && life_cycle_ &&
      life_cycle_->GetState() ==
          RemoteDeviceLifeCycle::State::SECURE_CHANNEL_ESTABLISHED) {
    proximity_monitor_->Start();
  } else {
    proximity_monitor_->Stop();
  }
}

void UnlockManager::SetWakingUpState(bool is_waking_up) {
  is_waking_up_ = is_waking_up;

  // Clear the waking up state after a timeout.
  clear_waking_up_state_weak_ptr_factory_.InvalidateWeakPtrs();
  if (is_waking_up_) {
    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
        FROM_HERE,
        base::Bind(&UnlockManager::SetWakingUpState,
                   clear_waking_up_state_weak_ptr_factory_.GetWeakPtr(), false),
        base::TimeDelta::FromSeconds(kWakingUpDurationSecs));
  }

  UpdateLockScreen();
}

void UnlockManager::AcceptAuthAttempt(bool should_accept) {
  if (!is_attempting_auth_)
    return;

  // Cancel the pending task to time out the auth attempt.
  reject_auth_attempt_weak_ptr_factory_.InvalidateWeakPtrs();

  if (should_accept)
    proximity_monitor_->RecordProximityMetricsOnAuthSuccess();

  is_attempting_auth_ = false;
  if (screenlock_type_ == ProximityAuthSystem::SIGN_IN) {
    PA_LOG(INFO) << "Finalizing sign-in...";
    proximity_auth_client_->FinalizeSignin(
        should_accept && sign_in_secret_ ? *sign_in_secret_ : std::string());
  } else {
    PA_LOG(INFO) << "Finalizing unlock...";
    proximity_auth_client_->FinalizeUnlock(should_accept);
  }
}

UnlockManager::RemoteScreenlockState
UnlockManager::GetScreenlockStateFromRemoteUpdate(RemoteStatusUpdate update) {
  switch (update.secure_screen_lock_state) {
    case SECURE_SCREEN_LOCK_DISABLED:
      return RemoteScreenlockState::DISABLED;

    case SECURE_SCREEN_LOCK_ENABLED:
      if (update.user_presence == USER_PRESENT)
        return RemoteScreenlockState::UNLOCKED;

      return RemoteScreenlockState::LOCKED;

    case SECURE_SCREEN_LOCK_STATE_UNKNOWN:
      return RemoteScreenlockState::UNKNOWN;
  }

  NOTREACHED();
  return RemoteScreenlockState::UNKNOWN;
}

Messenger* UnlockManager::GetMessenger() {
  // TODO(tengs): We should use a weak pointer to hold the Messenger instance
  // instead.
  if (!life_cycle_)
    return nullptr;
  return life_cycle_->GetMessenger();
}

}  // namespace proximity_auth