Allow root uid to listen for uid state changes across users.

ActivityManager.checkUidPermission() doesn't exempt root uids
similar to other permission checking methods. While we
investigate why, switch to a different permission checking
method.

Bug: 385438310
Test: atest ./tests/app/src/android/app/cts/ActivityManagerFgsBgStartTest.java
Flag: EXEMPT bugfix
Change-Id: I6f254f08f3dafe0156f2f6a77f3ef7ad461a0e65

1 files changed, 5 insertions, 2 deletions

diff --git a/services/core/java/com/android/server/am/UidObserverController.java b/services/core/java/com/android/server/am/UidObserverController.java
index 7eeec32cf24a..f58e3f85bb26 100644
--- a/services/core/java/com/android/server/am/UidObserverController.java
+++ b/services/core/java/com/android/server/am/UidObserverController.java
@@ -31,6 +31,7 @@ import android.os.Binder;
 import android.os.Handler;
 import android.os.IBinder;
 import android.os.Message;
+import android.os.Process;
 import android.os.RemoteCallbackList;
 import android.os.RemoteException;
 import android.os.SystemClock;
@@ -90,10 +91,12 @@ public class UidObserverController {
                 + UUID.randomUUID().toString());
 
         synchronized (mLock) {
+            final boolean canInteractAcrossUsers = ActivityManager.checkComponentPermission(
+                    INTERACT_ACROSS_USERS_FULL, callingUid, Process.INVALID_UID, true)
+                            == PackageManager.PERMISSION_GRANTED;
             mUidObservers.register(observer, new UidObserverRegistration(callingUid,
                     callingPackage, which, cutpoint,
-                    ActivityManager.checkUidPermission(INTERACT_ACROSS_USERS_FULL, callingUid)
-                    == PackageManager.PERMISSION_GRANTED, uids, token));
+                    canInteractAcrossUsers, uids, token));
         }
 
         return token;