Android runtime permissions for System app

Question

I'm building an android app and made it as system app by placing it under /system/priv-app (building AOSP) Android OS version : 6.0.1 (api 23)

ApplicationInfo ai = packageManager.getApplicationInfo(
                    packageName, 0);
            // Check if FLAG_SYSTEM or FLAG_UPDATED_SYSTEM_APP are set.
            if (ai != null
                    && (ai.flags & (ApplicationInfo.FLAG_SYSTEM | ApplicationInfo.FLAG_UPDATED_SYSTEM_APP)) != 0) {
                return true;
            }

This code retuns true (for system app)

I've read that system apps will have all the runtime permissions like location, storage, etc.

But it is still asking for permissions (system dialog) for location and storage.

What i've tried ?

1) used this permission in manifest "android.Manifest.permission.GRANT_RUNTIME_PERMISSIONS"

2) added few lines of code in framework

   services/core/java/com/android/server/pm/DefaultPermissionGrantPolicy.java

as mentioned here

but still app is asking for permissions.

note* : i'm also looking to get permissions for android.permission.WRITE_SETTINGS , WRITE_SECURE_SETTINGS and Draw over other apps without asking/prompting the user

One more note :*

This app is for a custom hardware with custom OS, i have access to all of framework code

Answer 1

At first, dump your package service and inspect the package has correct flag and permissions. If your app is privileged, privateFlags must have PRIVILEGED . If your app is privileged, all Runtime permissions are granted if it is requested in the manifest. However I'm not sure this is true on Android 6.0.

adb shell dumpsys package

Packages:
  Package [com.android.systemui] (4dfb5a):
....
  flags=[ SYSTEM HAS_CODE PERSISTENT ]
  privateFlags=[ PRIVILEGED DEFAULT_TO_DEVICE_PROTECTED_STORAGE DIRECT_BOOT_AWARE RESIZEABLE_ACTIVITIES ]
  dataDir=/data/user_de/0/com.android.systemui
....
  pkgFlags=[ SYSTEM HAS_CODE PERSISTENT ]
  declared permissions:
    com.android.systemui.permission.SELF: prot=signature, INSTALLED
  requested permissions:
    android.permission.RECEIVE_BOOT_COMPLETED
    android.permission.READ_EXTERNAL_STORAGE
....
  install permissions:
    android.permission.REAL_GET_TASKS: granted=true
    android.permission.REMOTE_AUDIO_PLAYBACK: granted=true

And please have a look this answer