[EasyUnlock] Force user to enter their password after 20 hours.

components/proximity_auth/proximity_auth_system.cc

 // Copyright 2014 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/proximity_auth_system.h"
 
+#include "base/sys_info.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/proximity_auth/logging/logging.h"
 #include "components/proximity_auth/proximity_auth_client.h"
+#include "components/proximity_auth/proximity_auth_pref_manager.h"
 #include "components/proximity_auth/remote_device_life_cycle_impl.h"
 #include "components/proximity_auth/unlock_manager_impl.h"
 
 namespace proximity_auth {
 
+namespace {
+
+// The maximum number of hours permitted before the user is forced is use their
+// password to authenticate.
+const int64_t kPasswordReauthPeriodHours = 20;
+
+}  // namespace
+
 ProximityAuthSystem::ProximityAuthSystem(
     ScreenlockType screenlock_type,
     ProximityAuthClient* proximity_auth_client)
     : proximity_auth_client_(proximity_auth_client),
       unlock_manager_(
           new UnlockManagerImpl(screenlock_type, proximity_auth_client)),
       suspended_(false),
       started_(false),
       weak_ptr_factory_(this) {}
 
@@ skipping 116 matching lines @@
     }
   }
 
   if (remote_devices_map_.find(account_id) == remote_devices_map_.end() ||
       remote_devices_map_[account_id].size() == 0) {
     PA_LOG(INFO) << "User " << account_id.Serialize()
                  << " does not have a RemoteDevice.";
     return;
   }
 
+  if (ShouldForcePassword()) {
+    PA_LOG(INFO) << "Forcing password reauth.";
+    proximity_auth_client_->UpdateScreenlockState(
+        ScreenlockState::PASSWORD_REAUTH);
+    return;
+  }
+
   // TODO(tengs): We currently assume each user has only one RemoteDevice, so we
   // can simply take the first item in the list.
   cryptauth::RemoteDevice remote_device = remote_devices_map_[account_id][0];
   if (!suspended_) {
     PA_LOG(INFO) << "Creating RemoteDeviceLifeCycle for focused user: "
                  << account_id.Serialize();
     remote_device_life_cycle_ = CreateRemoteDeviceLifeCycle(remote_device);
     unlock_manager_->SetRemoteDeviceLifeCycle(remote_device_life_cycle_.get());
     remote_device_life_cycle_->AddObserver(this);
     remote_device_life_cycle_->Start();
   }
 }
 
+bool ProximityAuthSystem::ShouldForcePassword() {
+  // TODO(tengs): Revisit this when adding tests.
+  if (!base::SysInfo::IsRunningOnChromeOS())
+    return false;
+
+  // TODO(tengs): Put this force password reauth logic behind an enterprise
+  // policy. See crbug.com/724717.
+  ProximityAuthPrefManager pref_manager(
+      proximity_auth_client_->GetPrefService());
+  int64_t now_ms = base::Time::Now().ToJavaTime();
+  int64_t last_password_ms = pref_manager.GetLastPasswordEntryTimestampMs();
+
+  if (now_ms < last_password_ms) {
+    PA_LOG(ERROR) << "Invalid last password timestamp: now=" << now_ms
+                  << ", last_password=" << last_password_ms;
+    return true;
+  }
+
+  return base::TimeDelta::FromMilliseconds(now_ms - last_password_ms) >
+         base::TimeDelta::FromHours(kPasswordReauthPeriodHours);
+}
+
 }  // proximity_auth