Add filtering for IPsec algorithms in IKEv2 VPNs

This commit adds support for validating and filtering IPsec algorithms.
Without a public API exposing IKEv2 algorithms (and their respective
public APIs), the allowedAlgorithms can only filter the proposals for
IPsec (Child) SA algorithms.

Additionally, this removes the HMAC_SHA1 from the IKE SA's integrity
algorithm proposals due to insecurity

Bug: 153701879
Test: FrameworksNetTests passing, new tests added
Change-Id: I7e61a1612692db275b751330af5bacbf86836a8c

tests/net/java/android/net/Ikev2VpnProfileTest.java

@@ -40,7 +40,10 @@ import java.security.KeyPair;
 import java.security.KeyPairGenerator;
 import java.security.PrivateKey;
 import java.security.cert.X509Certificate;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Date;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 
 import javax.security.auth.x500.X500Principal;
@@ -106,6 +109,7 @@ public class Ikev2VpnProfileTest {
         assertTrue(profile.isBypassable());
         assertTrue(profile.isMetered());
         assertEquals(TEST_MTU, profile.getMaxMtu());
+        assertEquals(Ikev2VpnProfile.DEFAULT_ALGORITHMS, profile.getAllowedAlgorithms());
     }
 
     @Test
@@ -159,6 +163,78 @@ public class Ikev2VpnProfileTest {
         assertNull(profile.getUserCert());
     }
 
+    @Test
+    public void testBuildWithAllowedAlgorithmsAead() throws Exception {
+        final Ikev2VpnProfile.Builder builder = getBuilderWithDefaultOptions();
+        builder.setAuthPsk(PSK_BYTES);
+
+        List<String> allowedAlgorithms = Arrays.asList(IpSecAlgorithm.AUTH_CRYPT_AES_GCM);
+        builder.setAllowedAlgorithms(allowedAlgorithms);
+
+        final Ikev2VpnProfile profile = builder.build();
+        assertEquals(allowedAlgorithms, profile.getAllowedAlgorithms());
+    }
+
+    @Test
+    public void testBuildWithAllowedAlgorithmsNormal() throws Exception {
+        final Ikev2VpnProfile.Builder builder = getBuilderWithDefaultOptions();
+        builder.setAuthPsk(PSK_BYTES);
+
+        List<String> allowedAlgorithms =
+                Arrays.asList(IpSecAlgorithm.AUTH_HMAC_SHA512, IpSecAlgorithm.CRYPT_AES_CBC);
+        builder.setAllowedAlgorithms(allowedAlgorithms);
+
+        final Ikev2VpnProfile profile = builder.build();
+        assertEquals(allowedAlgorithms, profile.getAllowedAlgorithms());
+    }
+
+    @Test
+    public void testSetAllowedAlgorithmsEmptyList() throws Exception {
+        final Ikev2VpnProfile.Builder builder = getBuilderWithDefaultOptions();
+
+        try {
+            builder.setAllowedAlgorithms(new ArrayList<>());
+            fail("Expected exception due to no valid algorithm set");
+        } catch (IllegalArgumentException expected) {
+        }
+    }
+
+    @Test
+    public void testSetAllowedAlgorithmsInvalidList() throws Exception {
+        final Ikev2VpnProfile.Builder builder = getBuilderWithDefaultOptions();
+        List<String> allowedAlgorithms = new ArrayList<>();
+
+        try {
+            builder.setAllowedAlgorithms(Arrays.asList(IpSecAlgorithm.AUTH_HMAC_SHA256));
+            fail("Expected exception due to missing encryption");
+        } catch (IllegalArgumentException expected) {
+        }
+
+        try {
+            builder.setAllowedAlgorithms(Arrays.asList(IpSecAlgorithm.CRYPT_AES_CBC));
+            fail("Expected exception due to missing authentication");
+        } catch (IllegalArgumentException expected) {
+        }
+    }
+
+    @Test
+    public void testSetAllowedAlgorithmsInsecureAlgorithm() throws Exception {
+        final Ikev2VpnProfile.Builder builder = getBuilderWithDefaultOptions();
+        List<String> allowedAlgorithms = new ArrayList<>();
+
+        try {
+            builder.setAllowedAlgorithms(Arrays.asList(IpSecAlgorithm.AUTH_HMAC_MD5));
+            fail("Expected exception due to insecure algorithm");
+        } catch (IllegalArgumentException expected) {
+        }
+
+        try {
+            builder.setAllowedAlgorithms(Arrays.asList(IpSecAlgorithm.AUTH_HMAC_SHA1));
+            fail("Expected exception due to insecure algorithm");
+        } catch (IllegalArgumentException expected) {
+        }
+    }
+
     @Test
     public void testBuildNoAuthMethodSet() throws Exception {
         final Ikev2VpnProfile.Builder builder = getBuilderWithDefaultOptions();