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

services/core/java/com/android/server/NsdService.java

@@ -41,6 +41,7 @@ import java.util.HashMap;
 import java.util.concurrent.CountDownLatch;
 
 import com.android.internal.util.AsyncChannel;
+import com.android.internal.util.DumpUtils;
 import com.android.internal.util.Protocol;
 import com.android.internal.util.State;
 import com.android.internal.util.StateMachine;
@@ -811,13 +812,7 @@ public class NsdService extends INsdManager.Stub {
 
     @Override
     public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
-        if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.DUMP)
-                != PackageManager.PERMISSION_GRANTED) {
-            pw.println("Permission Denial: can't dump ServiceDiscoverService from from pid="
-                    + Binder.getCallingPid()
-                    + ", uid=" + Binder.getCallingUid());
-            return;
-        }
+        if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;
 
         for (ClientInfo client : mClients.values()) {
             pw.println("Client Info");

services/core/java/com/android/server/net/NetworkStatsService.java

@@ -122,6 +122,7 @@ import android.util.proto.ProtoOutputStream;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.net.VpnInfo;
 import com.android.internal.util.ArrayUtils;
+import com.android.internal.util.DumpUtils;
 import com.android.internal.util.FileRotator;
 import com.android.internal.util.IndentingPrintWriter;
 import com.android.server.EventLogTags;
@@ -1234,7 +1235,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
 
     @Override
     protected void dump(FileDescriptor fd, PrintWriter rawWriter, String[] args) {
-        mContext.enforceCallingOrSelfPermission(DUMP, TAG);
+        if (!DumpUtils.checkDumpPermission(mContext, TAG, rawWriter)) return;
 
         long duration = DateUtils.DAY_IN_MILLIS;
         final HashSet<String> argSet = new HashSet<String>();