Adds caller check to getAllPackages()

This change enforces that only system, root or shell may call
getAllPackages(), a hidden API that shares all package names regardless
of user, instant app or package visibility rules.

Bug: 174661955
Merged-In: I77460ae19a4d41151577646441f11e2eddbb741a
(cherry picked from commit cca5bf9282)

Change-Id: I630cfd7c3be9bf6f2a6b8e132f6b8dda6b7fa274

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

@@ -5793,6 +5793,11 @@ public class PackageManagerService extends IPackageManager.Stub
     @Override
     public List<String> getAllPackages() {
         final int callingUid = Binder.getCallingUid();
+        // enforceSystemOrRootOrShell:
+        if (callingUid != Process.SYSTEM_UID && callingUid != Process.ROOT_UID
+                && callingUid != Process.SHELL_UID) {
+            throw new SecurityException("getAllPackages is limited to privileged callers");
+        }
         final int callingUserId = UserHandle.getUserId(callingUid);
         synchronized (mPackages) {
             if (canViewInstantApps(callingUid, callingUserId)) {