I'm trying to run an app on the android emulator with full kiosk mode. So I wrote a DeviceAdminReceiver: Here's the MainActivity: And finally here's the AndroidManifest.xml: > The problem is that this line in MainActivity throw this exception: I already have a device_admin.xml in resources/xml with a device-admin tag, does it need more configuration? Or is the issue else

Xamarin MAUI No Active Admin Security Exception (Kiosk mode app)

I’m trying to run an app on the android emulator with full kiosk mode. So I wrote a DeviceAdminReceiver:

public class AdminReceiver : DeviceAdminReceiver
{

    public override void OnEnabled(Context context, Intent intent)
    {
        base.OnEnabled(context, intent);
        Log.Info("Device Admin: ", "Enabled");
    }

    public override void OnDisabled(Context context, Intent intent)
    {
        base.OnDisabled(context, intent);
        Log.Info("Device Admin: ", "Disabled");
    }
}

Here’s the MainActivity:

[Activity(Theme = "@style/Maui.SplashTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize)]
[IntentFilter(new[] { Intent.ActionMain }, Categories = new[] { Intent.CategoryHome, Intent.CategoryDefault })]
public class MainActivity : MauiAppCompatActivity
{
    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        SetFullscreenFlags();
        var devicePolicyManager = (DevicePolicyManager)GetSystemService(Context.DevicePolicyService);
        var deviceAdminComponent = new ComponentName(this, Java.Lang.Class.FromType(typeof(AdminReceiver)));
        var intent = new Intent(DevicePolicyManager.ActionAddDeviceAdmin);
        intent.PutExtra(DevicePolicyManager.ExtraDeviceAdmin, deviceAdminComponent);
        intent.PutExtra(DevicePolicyManager.ExtraAddExplanation, "Device administrator");
        StartActivity(intent);
        
        devicePolicyManager.SetLockTaskPackages(deviceAdminComponent, new[] { PackageName });
        StartLockTask();
       
    }

private void SetFullscreenFlags()
    {
        Window.SetFlags(WindowManagerFlags.Fullscreen, WindowManagerFlags.Fullscreen);

        if (Build.VERSION.SdkInt >= BuildVersionCodes.R)
        {
            Window.SetDecorFitsSystemWindows(true);
            var controller = Window.InsetsController;
            if (controller is not null)
            {
                controller.Hide(WindowInsets.Type.StatusBars() | WindowInsets.Type.NavigationBars());
            }
        }
        else
        {
            Window.DecorView.SystemUiVisibility = (StatusBarVisibility)
                                     (SystemUiFlags.LowProfile
                                     | SystemUiFlags.Fullscreen
                                     | SystemUiFlags.LayoutFullscreen
                                     | SystemUiFlags.HideNavigation
                                     | SystemUiFlags.LayoutHideNavigation
                                     | SystemUiFlags.Immersive
                                     | SystemUiFlags.ImmersiveSticky);
        }
    }

And finally here’s the AndroidManifest.xml:

<uses-sdk android:minSdkVersion="21" android:targetSdkVersion="30" />
<application android:allowBackup="true" android:icon="@mipmap/appicon" android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true">
    <receiver
        android:name=".AdminReceiver"
        android:permission="android.permission.BIND_DEVICE_ADMIN">
        <meta-data
            android:name="android.app.device_admin"
            android:resource="@xml/device_admin" />
        <intent-filter>
            <action android:name="android.app.action.DEVICE_ADMIN_ENABLED" />
            <action android:name="android.app.action.DEVICE_ADMIN_DISABLED" />
        </intent-filter>
    </receiver>
    <receiver android:name=".BootReceiver">
        <intent-filter>
            <action android:name="android.intent.action.PROFILE_PROVISIONING_COMPLETE"/>
            <action android:name="android.intent.action.BOOT_COMPLETED" />
        </intent-filter>
    </receiver>
</application>

The problem is that this line in MainActivity throw this exception:

devicePolicyManager.SetLockTaskPackages(deviceAdminComponent, new[] { PackageName });

Java.Lang.SecurityException: 'No active admin ComponentInfo{com.companyName.TestApp/crc6463b464086cdcaa12.AdminReceiver}'

I already have a device_admin.xml in resources/xml with a device-admin tag, does it need more configuration? Or is the issue else where? Or maybe i’m instanciating two difference admin receiver?

Note: I already did the procedure to allow this app as device admin on the emulator and run the command via android debug bridge setting it as device owner:

dpm set-device-owner com.companyName.TestApp/.AdminReceiver

Answer

Can you ensure that you are actually registering your BroadcastReceiver with attributes on the class instead of modifying the AndroidManifest.xml manually. I think what is throwing you off is that if you don’t register the receiver, it will get named as <md5 sum>.AdminReceiver. However, when you are adding the reciever as .AdminReceiver in the AndroidManifest.xml, then Android will inflate that as <package name>.AdminReciever. So your AdminReceiver won’t get called.

So try something like:

[BroadcastReceiver(
    Name = "your.packagename.AdminReceiver",
    Description = "@string/device_owner_description",
    Label = "My Device Admin Receiver",
    Permission = Manifest.Permission.BindDeviceAdmin)]
[MetaData("android.app.device_admin", Resource = "@xml/device_admin")]
public class AdminReceiver : DeviceAdminReceiver
{
}

Then you should remove your entry in the manifest.

If you need to filter specific intents, you can also add the [IntentFilter] attribute to add those, but it shouldn’t be necessary for device admin.

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Answer