Add internal support for IPsec forward policies

This change adds support for IPsec forward policies, which are necessary
for packets to be allowed to be forwarded to another interface, as is
the case with tethering. This is necessary and useful only within the
system server, and as such is not exposed as a public API.

This change is safe, since the addition of a FWD policy on IPsec tunnel
interfaces will by default block forwarded traffic (as would be the case
without this patch). In the event that the (system) owner of the tunnel
requires support for forwarded packets (eg tethering), this patch allows
application of transforms in the FWD direction as well.

This will be used to ensure that the VCN can be used as the underlying
network for the purposes of tethering.

Bug: 185495453
Test: atest IpSecServiceTest
Test: atest IpSecServiceParameterizedTest
Test: manual testing with tethering over VCN
Change-Id: I74ecea71f1954029f6fbdbe34598c82e0aac386b

1 files changed, 85 insertions, 15 deletions

diff --git a/tests/net/java/com/android/server/IpSecServiceParameterizedTest.java b/tests/net/java/com/android/server/IpSecServiceParameterizedTest.java
index 32c95f149979..cf2c9c783ac7 100644
--- a/tests/net/java/com/android/server/IpSecServiceParameterizedTest.java
+++ b/tests/net/java/com/android/server/IpSecServiceParameterizedTest.java
@@ -16,9 +16,14 @@
 
 package com.android.server;
 
+import static android.content.pm.PackageManager.PERMISSION_DENIED;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.net.INetd.IF_STATE_DOWN;
 import static android.net.INetd.IF_STATE_UP;
+import static android.net.IpSecManager.DIRECTION_FWD;
+import static android.net.IpSecManager.DIRECTION_IN;
+import static android.net.IpSecManager.DIRECTION_OUT;
+import static android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK;
 import static android.system.OsConstants.AF_INET;
 import static android.system.OsConstants.AF_INET6;
 
@@ -56,6 +61,7 @@ import android.os.Binder;
 import android.os.ParcelFileDescriptor;
 import android.system.Os;
 import android.test.mock.MockContext;
+import android.util.ArraySet;
 
 import androidx.test.filters.SmallTest;
 
@@ -71,6 +77,7 @@ import java.net.Inet4Address;
 import java.net.Socket;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Set;
 
 /** Unit tests for {@link IpSecService}. */
 @SmallTest
@@ -119,7 +126,18 @@ public class IpSecServiceParameterizedTest {
     AppOpsManager mMockAppOps = mock(AppOpsManager.class);
     ConnectivityManager mMockConnectivityMgr = mock(ConnectivityManager.class);
 
-    MockContext mMockContext = new MockContext() {
+    TestContext mTestContext = new TestContext();
+
+    private class TestContext extends MockContext {
+        private Set<String> mAllowedPermissions = new ArraySet<>(Arrays.asList(
+                android.Manifest.permission.MANAGE_IPSEC_TUNNELS,
+                android.Manifest.permission.NETWORK_STACK,
+                PERMISSION_MAINLINE_NETWORK_STACK));
+
+        private void setAllowedPermissions(String... permissions) {
+            mAllowedPermissions = new ArraySet<>(permissions);
+        }
+
         @Override
         public Object getSystemService(String name) {
             switch(name) {
@@ -147,20 +165,22 @@ public class IpSecServiceParameterizedTest {
 
         @Override
         public void enforceCallingOrSelfPermission(String permission, String message) {
-            if (permission == android.Manifest.permission.MANAGE_IPSEC_TUNNELS) {
+            if (mAllowedPermissions.contains(permission)) {
                 return;
+            } else {
+                throw new SecurityException("Unavailable permission requested");
             }
-            throw new SecurityException("Unavailable permission requested");
         }
 
         @Override
         public int checkCallingOrSelfPermission(String permission) {
-            if (android.Manifest.permission.NETWORK_STACK.equals(permission)) {
+            if (mAllowedPermissions.contains(permission)) {
                 return PERMISSION_GRANTED;
+            } else {
+                return PERMISSION_DENIED;
             }
-            throw new UnsupportedOperationException();
         }
-    };
+    }
 
     INetd mMockNetd;
     PackageManager mMockPkgMgr;
@@ -194,7 +214,7 @@ public class IpSecServiceParameterizedTest {
         mMockNetd = mock(INetd.class);
         mMockPkgMgr = mock(PackageManager.class);
         mMockIpSecSrvConfig = mock(IpSecService.IpSecServiceConfiguration.class);
-        mIpSecService = new IpSecService(mMockContext, mMockIpSecSrvConfig);
+        mIpSecService = new IpSecService(mTestContext, mMockIpSecSrvConfig);
 
         // Injecting mock netd
         when(mMockIpSecSrvConfig.getNetdInstance()).thenReturn(mMockNetd);
@@ -664,6 +684,21 @@ public class IpSecServiceParameterizedTest {
 
         assertNotNull(createTunnelResp);
         assertEquals(IpSecManager.Status.OK, createTunnelResp.status);
+        for (int direction : new int[] {DIRECTION_IN, DIRECTION_OUT, DIRECTION_FWD}) {
+            for (int selAddrFamily : ADDRESS_FAMILIES) {
+                verify(mMockNetd).ipSecAddSecurityPolicy(
+                        eq(mUid),
+                        eq(selAddrFamily),
+                        eq(direction),
+                        anyString(),
+                        anyString(),
+                        eq(0),
+                        anyInt(), // iKey/oKey
+                        anyInt(), // mask
+                        eq(createTunnelResp.resourceId));
+            }
+        }
+
         return createTunnelResp;
     }
 
@@ -798,16 +833,51 @@ public class IpSecServiceParameterizedTest {
     }
 
     @Test
-    public void testApplyTunnelModeTransform() throws Exception {
-        verifyApplyTunnelModeTransformCommon(false);
+    public void testApplyTunnelModeTransformOutbound() throws Exception {
+        verifyApplyTunnelModeTransformCommon(false /* closeSpiBeforeApply */, DIRECTION_OUT);
     }
 
     @Test
-    public void testApplyTunnelModeTransformReleasedSpi() throws Exception {
-        verifyApplyTunnelModeTransformCommon(true);
+    public void testApplyTunnelModeTransformOutboundNonNetworkStack() throws Exception {
+        mTestContext.setAllowedPermissions(android.Manifest.permission.MANAGE_IPSEC_TUNNELS);
+        verifyApplyTunnelModeTransformCommon(false /* closeSpiBeforeApply */, DIRECTION_OUT);
     }
 
-    public void verifyApplyTunnelModeTransformCommon(boolean closeSpiBeforeApply) throws Exception {
+    @Test
+    public void testApplyTunnelModeTransformOutboundReleasedSpi() throws Exception {
+        verifyApplyTunnelModeTransformCommon(true /* closeSpiBeforeApply */, DIRECTION_OUT);
+    }
+
+    @Test
+    public void testApplyTunnelModeTransformInbound() throws Exception {
+        verifyApplyTunnelModeTransformCommon(true /* closeSpiBeforeApply */, DIRECTION_IN);
+    }
+
+    @Test
+    public void testApplyTunnelModeTransformInboundNonNetworkStack() throws Exception {
+        mTestContext.setAllowedPermissions(android.Manifest.permission.MANAGE_IPSEC_TUNNELS);
+        verifyApplyTunnelModeTransformCommon(true /* closeSpiBeforeApply */, DIRECTION_IN);
+    }
+
+    @Test
+    public void testApplyTunnelModeTransformForward() throws Exception {
+        verifyApplyTunnelModeTransformCommon(true /* closeSpiBeforeApply */, DIRECTION_FWD);
+    }
+
+    @Test
+    public void testApplyTunnelModeTransformForwardNonNetworkStack() throws Exception {
+        mTestContext.setAllowedPermissions(android.Manifest.permission.MANAGE_IPSEC_TUNNELS);
+
+        try {
+            verifyApplyTunnelModeTransformCommon(true /* closeSpiBeforeApply */, DIRECTION_FWD);
+            fail("Expected security exception due to use of forward policies without NETWORK_STACK"
+                     + " or MAINLINE_NETWORK_STACK permission");
+        } catch (SecurityException expected) {
+        }
+    }
+
+    public void verifyApplyTunnelModeTransformCommon(boolean closeSpiBeforeApply, int direction)
+            throws Exception {
         IpSecConfig ipSecConfig = new IpSecConfig();
         ipSecConfig.setMode(IpSecTransform.MODE_TUNNEL);
         addDefaultSpisAndRemoteAddrToIpSecConfig(ipSecConfig);
@@ -825,17 +895,17 @@ public class IpSecServiceParameterizedTest {
         int transformResourceId = createTransformResp.resourceId;
         int tunnelResourceId = createTunnelResp.resourceId;
         mIpSecService.applyTunnelModeTransform(
-                tunnelResourceId, IpSecManager.DIRECTION_OUT, transformResourceId, BLESSED_PACKAGE);
+                tunnelResourceId, direction, transformResourceId, BLESSED_PACKAGE);
 
         for (int selAddrFamily : ADDRESS_FAMILIES) {
             verify(mMockNetd)
                     .ipSecUpdateSecurityPolicy(
                             eq(mUid),
                             eq(selAddrFamily),
-                            eq(IpSecManager.DIRECTION_OUT),
+                            eq(direction),
                             anyString(),
                             anyString(),
-                            eq(TEST_SPI),
+                            eq(direction == DIRECTION_OUT ? TEST_SPI : 0),
                             anyInt(), // iKey/oKey
                             anyInt(), // mask
                             eq(tunnelResourceId));