Grant USB permissions as device owner

Question

A device owner can grant runtime permissions to a third-party app using DevicePolicyManager.setPermissionGrantState() to avoid user prompts.

But is there any way for a device owner to grant USB permissions as well, so that this app gets access to plugged USB devices without user prompt ?

I've tried to call UsbManager.grantPermission() (with reflection) but it raises a SecurityException since it requires the MANAGE_USB permission which is granted only to system apps (and not to device owner, obviously).

NB: I'm looking for a solution working on a non-root & non-custom Android system, the device owner app is set using Android Enterprise provisioning methods.

Bywoods

Take a look here, if it helps: #13648047 – Hexagonal

@GauravMall Unfortunately all the suggested answers require to be a system app – Bywoods

Yeah, sorry, that detail just passed over my head. I don't know how. Did it help you, however? – Hexagonal

@GauravMall Not really. Surprinsingly it feels like an impossible thing to do. – Bywoods

Did you find a solution for it? Even UsbManager.grantPermission() (with reflection) deosn't work anymore on Android 9 with root system app – Brownley

found solution for Android 9 https://mcmap.net/q/340966/-bypass-android-usb-host-permission-confirmation-dialog-on-android-9 – Brownley

@Brownley this solution requires root access – Bywoods

@fiddler yes, I know. But it's the only possible solution – Brownley

@Brownley gives me an error: "W/System.err: java.lang.reflect.InvocationTargetException" in "grantDevicePermissionMethod.invoke(iUsbManager, usbDevice,appInfo.uid); " – Yorgo

Answer 1

There is a special system config to disable USB permission dialogs: https://github.com/aosp-mirror/platform_frameworks_base/blob/8ff4a5a5b510e724b25ac00369696594bb0c9fdc/core/res/res/values/config.xml#L2283

Maybe you can also change it at runtime with root privileges using setprop.

Another way is to customize the UsbUserSettingsManager class, specifically this method: https://android.googlesource.com/platform/frameworks/base.git/+/master/services/usb/java/com/android/server/usb/UsbUserSettingsManager.java#178

I assumed that as a device owner you have full control over your ROM source code.

Dogger

Unfortunately this is not a custom ROM and I don't have root access. The device owner app is set using standard provisioning methods. Therefore I cannot use any of these solutions. – Bywoods

Maybe your device owner app could declare the appropriate intent filter and react to plugging in of the USB device by calling grantDevicePermission() on UsbManager for a uid of the third party app which it can get in some other way? The idea is similar to what is done in onDestroy() here: android.googlesource.com/platform/frameworks/base/+/… – Dogger

I've just tried it, but unfortunately the UsbManager.grantPermission() methods require the MANAGE_USB permission which is only granted to system & privileged app, but not device owner apps. – Bywoods

Did you manage to find any way to do it without OS source code ? – Eyesight

Did anyone find an adb prop to toggle this config parameter? It looks like it is built in at build time and not exposed through ADB. – Corrody

One could use adb shell setprop persist.sys.usb.config_disableUsbPermissionDialogs true, but on my device it does not work.... – Kerplunk

Answer 2

It's a bit old, but hopefully it helps s.o. else. I've been using this for granting permission to apps

public boolean setPermissionGrantState (ComponentName admin, 
                String packageName, 
                String permission, 
                int grantState)

Link: https://developer.android.com/reference/android/app/admin/DevicePolicyManager#setPermissionGrantState(android.content.ComponentName,%20java.lang.String,%20java.lang.String,%20int)

Blatt

AFAIK that doesn't work with USB permissions (I already mentioned this method in my question) – Bywoods