Consistent dump() permission checking.

This change introduces new methods on DumpUtils that can check if the
caller has DUMP and/or PACKAGE_USAGE_STATS access.  It then moves all
existing dump() methods to use these checks so that we emit
consistent error messages.

Test: cts-tradefed run commandAndExit cts-dev -m CtsSecurityTestCases -t android.security.cts.ServicePermissionsTest
Bug: 32806790
Change-Id: Iaff6b9506818ee082b1e169c89ebe1001b3bfeca
diff --git a/services/core/java/com/android/server/DropBoxManagerService.java b/services/core/java/com/android/server/DropBoxManagerService.java
index 040d22c..894bca3 100644
--- a/services/core/java/com/android/server/DropBoxManagerService.java
+++ b/services/core/java/com/android/server/DropBoxManagerService.java
@@ -40,6 +40,7 @@
 import libcore.io.IoUtils;
 
 import com.android.internal.os.IDropBoxManagerService;
+import com.android.internal.util.DumpUtils;
 
 import java.io.BufferedOutputStream;
 import java.io.File;
@@ -350,11 +351,7 @@
     }
 
     public synchronized void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
-        if (getContext().checkCallingOrSelfPermission(android.Manifest.permission.DUMP)
-                != PackageManager.PERMISSION_GRANTED) {
-            pw.println("Permission Denial: Can't dump DropBoxManagerService");
-            return;
-        }
+        if (!DumpUtils.checkDumpPermission(getContext(), TAG, pw)) return;
 
         try {
             init();