Use Vpn rules (not firewall) for always-on VPN

Firewall rules don't work on 464xlat because they were created under
an assumption that there's only one address for the server and it's
ipv4, which doesn't go so well when we're on an ipv6-only network.

Bug: 33159037
Test: runtest -x net/java/com/android/server/connectivity/VpnTest.java
Change-Id: Id331526367fe13838874961da194b07bd50d4c97

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

@@ -3702,17 +3702,9 @@ public class ConnectivityService extends IConnectivityManager.Stub
             existing.shutdown();
         }
 
-        try {
+        if (tracker != null) {
-            if (tracker != null) {
+            mLockdownTracker = tracker;
-                mNetd.setFirewallEnabled(true);
+            mLockdownTracker.init();
-                mNetd.setFirewallInterfaceRule("lo", true);
-                mLockdownTracker = tracker;
-                mLockdownTracker.init();
-            } else {
-                mNetd.setFirewallEnabled(false);
-            }
-        } catch (RemoteException e) {
-            // ignored; NMS lives inside system_server
         }
     }
 

tests/net/java/com/android/server/connectivity/VpnTest.java

@@ -27,6 +27,7 @@ import android.annotation.UserIdInt;
 import android.app.AppOpsManager;
 import android.app.NotificationManager;
 import android.content.Context;
+import android.content.Intent;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.UserInfo;
@@ -42,6 +43,8 @@ import android.test.suitebuilder.annotation.SmallTest;
 import android.util.ArrayMap;
 import android.util.ArraySet;
 
+import com.android.internal.net.VpnConfig;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Map;
@@ -101,8 +104,10 @@ public class VpnTest extends AndroidTestCase {
     @Override
     public void setUp() throws Exception {
         MockitoAnnotations.initMocks(this);
+
         when(mContext.getPackageManager()).thenReturn(mPackageManager);
         setMockedPackages(mPackages);
+
         when(mContext.getPackageName()).thenReturn(Vpn.class.getPackage().getName());
         when(mContext.getSystemService(eq(Context.USER_SERVICE))).thenReturn(mUserManager);
         when(mContext.getSystemService(eq(Context.APP_OPS_SERVICE))).thenReturn(mAppOps);
@@ -257,6 +262,58 @@ public class VpnTest extends AndroidTestCase {
         }));
     }
 
+    @SmallTest
+    public void testLockdownRuleRepeatability() throws Exception {
+        final Vpn vpn = createVpn(primaryUser.id);
+
+        // Given legacy lockdown is already enabled,
+        vpn.setLockdown(true);
+        verify(mNetService, times(1)).setAllowOnlyVpnForUids(
+                eq(true), aryEq(new UidRange[] {UidRange.createForUser(primaryUser.id)}));
+
+        // Enabling legacy lockdown twice should do nothing.
+        vpn.setLockdown(true);
+        verify(mNetService, times(1)).setAllowOnlyVpnForUids(anyBoolean(), any(UidRange[].class));
+
+        // And disabling should remove the rules exactly once.
+        vpn.setLockdown(false);
+        verify(mNetService, times(1)).setAllowOnlyVpnForUids(
+                eq(false), aryEq(new UidRange[] {UidRange.createForUser(primaryUser.id)}));
+
+        // Removing the lockdown again should have no effect.
+        vpn.setLockdown(false);
+        verify(mNetService, times(2)).setAllowOnlyVpnForUids(anyBoolean(), any(UidRange[].class));
+    }
+
+    @SmallTest
+    public void testLockdownRuleReversibility() throws Exception {
+        final Vpn vpn = createVpn(primaryUser.id);
+
+        final UidRange[] entireUser = {
+            UidRange.createForUser(primaryUser.id)
+        };
+        final UidRange[] exceptPkg0 = {
+            new UidRange(entireUser[0].start, entireUser[0].start + PKG_UIDS[0] - 1),
+            new UidRange(entireUser[0].start + PKG_UIDS[0] + 1, entireUser[0].stop)
+        };
+
+        final InOrder order = inOrder(mNetService);
+
+        // Given lockdown is enabled with no package (legacy VPN),
+        vpn.setLockdown(true);
+        order.verify(mNetService).setAllowOnlyVpnForUids(eq(true), aryEq(entireUser));
+
+        // When a new VPN package is set the rules should change to cover that package.
+        vpn.prepare(null, PKGS[0]);
+        order.verify(mNetService).setAllowOnlyVpnForUids(eq(false), aryEq(entireUser));
+        order.verify(mNetService).setAllowOnlyVpnForUids(eq(true), aryEq(exceptPkg0));
+
+        // When that VPN package is unset, everything should be undone again in reverse.
+        vpn.prepare(null, VpnConfig.LEGACY_VPN);
+        order.verify(mNetService).setAllowOnlyVpnForUids(eq(false), aryEq(exceptPkg0));
+        order.verify(mNetService).setAllowOnlyVpnForUids(eq(true), aryEq(entireUser));
+    }
+
     @SmallTest
     public void testNotificationShownForAlwaysOnApp() {
         final UserHandle userHandle = UserHandle.of(primaryUser.id);