services: devicepolicy: Restore backup service as system

Restoring the backup service must be performed by either system
or root otherwise it will cause a SecurityException. This patch
clears the uid, performs the call as system and then restores it.

Fixes the following CTS tests:

com.android.cts.devicepolicy.CustomDeviceOwnerTest
  -- testOwnerChangedBroadcast
  -- testSilentPackageInstall

com.android.cts.devicepolicy.DeviceOwnerTest
  -- testCaCertManagement
  -- testCannotSetDeviceOwnerAgain
  -- testDeviceOwnerSetup
  -- testKeyManagement
  -- testLockTask
  -- testSystemUpdatePolicy
  -- testWifiConfigLockdown

com.android.cts.devicepolicy.MixedDeviceOwnerTest
  -- testAccountManagement
  -- testApplicationRestrictions
  -- testDelegatedCertInstaller
  -- testPermissionGrant
  -- testPermissionGrantPreMApp
  -- testPermissionMixedPolicies
  -- testPermissionPolicy
  -- testPermissionPrompts
  -- testPersistentIntentResolving
  -- testScreenCaptureDisabled

Change-Id: Ia26222f1fece14217554459c42679f82f7ceb980

1 files changed, 3 insertions, 0 deletions

diff --git a/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java b/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java
index 3901082..b2cb2ff 100644
--- a/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java
+++ b/services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java
@@ -4268,12 +4268,15 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {
                 mDeviceOwner.writeOwnerFile();
                 updateDeviceOwnerLocked();
                 // Restore backup manager.
+                long ident = Binder.clearCallingIdentity();
                 try {
                     IBackupManager ibm = IBackupManager.Stub.asInterface(
                             ServiceManager.getService(Context.BACKUP_SERVICE));
                     ibm.setBackupServiceActive(UserHandle.USER_OWNER, true);
                 } catch (RemoteException e) {
                     throw new IllegalStateException("Failed activating backup service.", e);
+                } finally {
+                    Binder.restoreCallingIdentity(ident);
                 }
             }
         }