Restrict VPN Diagnostics callbacks to underlying networks.

ConnectivityDiagnosticsCallbacks should only be invoked for the
underlying networks declared by active VPNs. This encourages VPN apps to
declare their underlying networks.

The previous permission model for VPNs allowed active VPNs to receive
callbacks on any network.

Bug: 148903617
Test: atest FrameworksNetTests
Change-Id: Ic08cdd2e2532580fda0fd3034e2bdff27e0ff84b
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index 5f0a53c..f060368 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -7890,10 +7890,13 @@
             return false;
         }
 
+        final Network[] underlyingNetworks;
         synchronized (mVpns) {
-            if (getVpnIfOwner(callbackUid) != null) {
-                return true;
-            }
+            final Vpn vpn = getVpnIfOwner(callbackUid);
+            underlyingNetworks = (vpn == null) ? null : vpn.getUnderlyingNetworks();
+        }
+        if (underlyingNetworks != null) {
+            if (Arrays.asList(underlyingNetworks).contains(nai.network)) return true;
         }
 
         // Administrator UIDs also contains the Owner UID
diff --git a/tests/net/java/com/android/server/ConnectivityServiceTest.java b/tests/net/java/com/android/server/ConnectivityServiceTest.java
index 6985415..5149d41 100644
--- a/tests/net/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/net/java/com/android/server/ConnectivityServiceTest.java
@@ -307,6 +307,8 @@
 
     private static final long TIMESTAMP = 1234L;
 
+    private static final int NET_ID = 110;
+
     private static final String CLAT_PREFIX = "v4-";
     private static final String MOBILE_IFNAME = "test_rmnet_data0";
     private static final String WIFI_IFNAME = "test_wlan0";
@@ -1016,6 +1018,7 @@
         private int mVpnType = VpnManager.TYPE_VPN_SERVICE;
 
         private VpnInfo mVpnInfo;
+        private Network[] mUnderlyingNetworks;
 
         public MockVpn(int userId) {
             super(startHandlerThreadAndReturnLooper(), mServiceContext, mNetworkManagementService,
@@ -1105,9 +1108,21 @@
             return super.getVpnInfo();
         }
 
-        private void setVpnInfo(VpnInfo vpnInfo) {
+        private synchronized void setVpnInfo(VpnInfo vpnInfo) {
             mVpnInfo = vpnInfo;
         }
+
+        @Override
+        public synchronized Network[] getUnderlyingNetworks() {
+            if (mUnderlyingNetworks != null) return mUnderlyingNetworks;
+
+            return super.getUnderlyingNetworks();
+        }
+
+        /** Don't override behavior for {@link Vpn#setUnderlyingNetworks}. */
+        private synchronized void overrideUnderlyingNetworks(Network[] underlyingNetworks) {
+            mUnderlyingNetworks = underlyingNetworks;
+        }
     }
 
     private void mockVpn(int uid) {
@@ -6774,9 +6789,10 @@
 
     @Test
     public void testCheckConnectivityDiagnosticsPermissionsActiveVpn() throws Exception {
+        final Network network = new Network(NET_ID);
         final NetworkAgentInfo naiWithoutUid =
                 new NetworkAgentInfo(
-                        null, null, null, null, null, new NetworkCapabilities(), 0,
+                        null, null, network, null, null, new NetworkCapabilities(), 0,
                         mServiceContext, null, null, mService, null, null, null, 0);
 
         setupLocationPermissions(Build.VERSION_CODES.Q, true, AppOpsManager.OPSTR_FINE_LOCATION,
@@ -6789,11 +6805,19 @@
         info.ownerUid = Process.myUid();
         info.vpnIface = "interface";
         mMockVpn.setVpnInfo(info);
+        mMockVpn.overrideUnderlyingNetworks(new Network[] {network});
         assertTrue(
                 "Active VPN permission not applied",
                 mService.checkConnectivityDiagnosticsPermissions(
                         Process.myPid(), Process.myUid(), naiWithoutUid,
                         mContext.getOpPackageName()));
+
+        mMockVpn.overrideUnderlyingNetworks(null);
+        assertFalse(
+                "VPN shouldn't receive callback on non-underlying network",
+                mService.checkConnectivityDiagnosticsPermissions(
+                        Process.myPid(), Process.myUid(), naiWithoutUid,
+                        mContext.getOpPackageName()));
     }
 
     @Test