chrome/browser/chromeos/system/device_disabling_manager.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_CHROMEOS_SYSTEM_DEVICE_DISABLING_MANAGER_H_
   6 #define CHROME_BROWSER_CHROMEOS_SYSTEM_DEVICE_DISABLING_MANAGER_H_
   7
   8 #include <string>
   9
  10 #include "base/callback.h"
  11 #include "base/macros.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/memory/weak_ptr.h"
  14 #include "base/observer_list.h"
  15 #include "chrome/browser/chromeos/settings/cros_settings.h"
  16
  17 namespace policy {
  18 class BrowserPolicyConnectorChromeOS;
  19 }
  20
  21 namespace user_manager {
  22 class UserManager;
  23 }
  24
  25 namespace chromeos {
  26 namespace system {
  27
  28 // If an enrolled device is lost or stolen, it can be remotely disabled by its
  29 // owner. The disabling is triggered in two different ways, depending on the
  30 // state the device is in:
  31 // - If the device has been wiped, it will perform a hash dance during OOBE to
  32 //   find out whether any persistent state has been stored for it on the server.
  33 //   If so, persistent state is retrieved as a |DeviceStateRetrievalResponse|
  34 //   protobuf, parsed and written to the |prefs::kServerBackedDeviceState| local
  35 //   state pref. At the appropriate place in the OOBE flow, the
  36 //   |WizardController| will call CheckWhetherDeviceDisabledDuringOOBE() to find
  37 //   out whether the device is disabled, causing it to either show or skip the
  38 //   device disabled screen.
  39 // - If the device has not been wiped, the disabled state is retrieved with
  40 //   every device policy fetch as part of the |PolicyData| protobuf, parsed and
  41 //   written to the |chromeos::kDeviceDisabled| cros setting. This class
  42 //   monitors the cros setting. When the device becomes disabled, one of two
  43 //   actions is taken:
  44 //   1) If no session is in progress, the device disabled screen is shown
  45 //      immediately.
  46 //   2) If a session is in progress, the session is terminated. After Chrome has
  47 //      restarted on the login screen, the disabled screen is shown per 1).
  48 //   This ensures that when a device is disabled, there is never any user
  49 //   session running in the backround.
  50 //   When the device is re-enabled, Chrome is restarted once more to resume the
  51 //   regular login screen flows from a known-good point.
  52 class DeviceDisablingManager {
  53  public:
  54   using DeviceDisabledCheckCallback = base::Callback<void(bool)>;
  55
  56   class Observer {
  57    public:
  58     virtual ~Observer();
  59
  60     virtual void OnDisabledMessageChanged(
  61      const std::string& disabled_message) = 0;
  62
  63    private:
  64     DISALLOW_ASSIGN(Observer);
  65   };
  66
  67   class Delegate {
  68    public:
  69     virtual ~Delegate();
  70
  71     // Terminate the current session (if any) and restart Chrome to show the
  72     // login screen.
  73     virtual void RestartToLoginScreen() = 0;
  74
  75     // Show the device disabled screen.
  76     virtual void ShowDeviceDisabledScreen() = 0;
  77
  78    private:
  79     DISALLOW_ASSIGN(Delegate);
  80   };
  81
  82   // |delegate| must outlive |this|.
  83   DeviceDisablingManager(Delegate* delegate,
  84                          CrosSettings* cros_settings,
  85                          user_manager::UserManager* user_manager);
  86   ~DeviceDisablingManager();
  87
  88   void AddObserver(Observer* observer);
  89   void RemoveObserver(Observer* observer);
  90
  91   // Returns the cached domain that owns the device. The domain is only
  92   // guaranteed to be up to date if the disabled screen was triggered.
  93   const std::string& enrollment_domain() const { return enrollment_domain_; }
  94
  95   // Returns the cached disabled message. The message is only guaranteed to be
  96   // up to date if the disabled screen was triggered.
  97   const std::string& disabled_message() const { return disabled_message_; }
  98
  99   // Performs a check whether the device is disabled during OOBE. |callback|
 100   // will be invoked with the result of the check.
 101   void CheckWhetherDeviceDisabledDuringOOBE(
 102       const DeviceDisabledCheckCallback& callback);
 103
 104   // Whenever trusted cros settings indicate that the device is disabled, this
 105   // method should be used to check whether the device disabling is to be
 106   // honored. If this method returns false, the device should not be disabled.
 107   static bool HonorDeviceDisablingDuringNormalOperation();
 108
 109  private:
 110   void Init();
 111
 112   // Cache the disabled message and inform observers if it changed.
 113   void CacheDisabledMessageAndNotify(const std::string& disabled_message);
 114
 115   void UpdateFromCrosSettings();
 116
 117   Delegate* delegate_;
 118   policy::BrowserPolicyConnectorChromeOS* browser_policy_connector_;
 119   CrosSettings* cros_settings_;
 120   user_manager::UserManager* user_manager_;
 121
 122   base::ObserverList<Observer> observers_;
 123
 124   scoped_ptr<CrosSettings::ObserverSubscription> device_disabled_subscription_;
 125   scoped_ptr<CrosSettings::ObserverSubscription> disabled_message_subscription_;
 126
 127   // Indicates whether the device was disabled when the cros settings were last
 128   // read.
 129   bool device_disabled_;
 130
 131   // A cached copy of the domain that owns the device.
 132   std::string enrollment_domain_;
 133
 134   // A cached copy of the message to show on the device disabled screen.
 135   std::string disabled_message_;
 136
 137   base::WeakPtrFactory<DeviceDisablingManager> weak_factory_;
 138
 139   DISALLOW_COPY_AND_ASSIGN(DeviceDisablingManager);
 140 };
 141
 142 }  // namespace system
 143 }  // namespace chromeos
 144
 145 #endif  // CHROME_BROWSER_CHROMEOS_SYSTEM_DEVICE_DISABLING_MANAGER_H_