/* * Copyright (C) 2020 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.android.server.connectivity; import static android.net.ConnectivityManager.NetworkCallback; import static android.net.ipsec.ike.SaProposal.DH_GROUP_2048_BIT_MODP; import static android.net.ipsec.ike.SaProposal.ENCRYPTION_ALGORITHM_AES_CBC; import static android.net.ipsec.ike.SaProposal.ENCRYPTION_ALGORITHM_AES_GCM_12; import static android.net.ipsec.ike.SaProposal.ENCRYPTION_ALGORITHM_AES_GCM_16; import static android.net.ipsec.ike.SaProposal.ENCRYPTION_ALGORITHM_AES_GCM_8; import static android.net.ipsec.ike.SaProposal.INTEGRITY_ALGORITHM_AES_XCBC_96; import static android.net.ipsec.ike.SaProposal.INTEGRITY_ALGORITHM_HMAC_SHA2_256_128; import static android.net.ipsec.ike.SaProposal.INTEGRITY_ALGORITHM_HMAC_SHA2_384_192; import static android.net.ipsec.ike.SaProposal.INTEGRITY_ALGORITHM_HMAC_SHA2_512_256; import static android.net.ipsec.ike.SaProposal.KEY_LEN_AES_128; import static android.net.ipsec.ike.SaProposal.KEY_LEN_AES_192; import static android.net.ipsec.ike.SaProposal.KEY_LEN_AES_256; import static android.net.ipsec.ike.SaProposal.PSEUDORANDOM_FUNCTION_AES128_XCBC; import static android.net.ipsec.ike.SaProposal.PSEUDORANDOM_FUNCTION_HMAC_SHA1; import android.annotation.NonNull; import android.content.Context; import android.net.Ikev2VpnProfile; import android.net.InetAddresses; import android.net.IpPrefix; import android.net.IpSecAlgorithm; import android.net.IpSecTransform; import android.net.Network; import android.net.RouteInfo; import android.net.eap.EapSessionConfig; import android.net.ipsec.ike.ChildSaProposal; import android.net.ipsec.ike.ChildSessionCallback; import android.net.ipsec.ike.ChildSessionConfiguration; import android.net.ipsec.ike.ChildSessionParams; import android.net.ipsec.ike.IkeFqdnIdentification; import android.net.ipsec.ike.IkeIdentification; import android.net.ipsec.ike.IkeIpv4AddrIdentification; import android.net.ipsec.ike.IkeIpv6AddrIdentification; import android.net.ipsec.ike.IkeKeyIdIdentification; import android.net.ipsec.ike.IkeRfc822AddrIdentification; import android.net.ipsec.ike.IkeSaProposal; import android.net.ipsec.ike.IkeSessionCallback; import android.net.ipsec.ike.IkeSessionConfiguration; import android.net.ipsec.ike.IkeSessionParams; import android.net.ipsec.ike.IkeTrafficSelector; import android.net.ipsec.ike.TunnelModeChildSessionParams; import android.net.ipsec.ike.exceptions.IkeException; import android.net.ipsec.ike.exceptions.IkeProtocolException; import android.net.util.IpRange; import android.system.OsConstants; import android.util.Log; import com.android.internal.net.VpnProfile; import com.android.internal.util.HexDump; import java.net.Inet4Address; import java.net.Inet6Address; import java.net.InetAddress; import java.util.ArrayList; import java.util.Arrays; import java.util.Collection; import java.util.HashSet; import java.util.List; /** * Utility class to build and convert IKEv2/IPsec parameters. * * @hide */ public class VpnIkev2Utils { private static final String TAG = VpnIkev2Utils.class.getSimpleName(); // TODO: Use IKE library exposed constants when @SystemApi is updated. /** IANA-defined 3072 group for use in IKEv2 */ private static final int DH_GROUP_3072_BIT_MODP = 15; /** IANA-defined 4096 group for use in IKEv2 */ private static final int DH_GROUP_4096_BIT_MODP = 16; static IkeSessionParams buildIkeSessionParams( @NonNull Context context, @NonNull Ikev2VpnProfile profile, @NonNull Network network) { final IkeIdentification localId = parseIkeIdentification(profile.getUserIdentity()); final IkeIdentification remoteId = parseIkeIdentification(profile.getServerAddr()); final IkeSessionParams.Builder ikeOptionsBuilder = new IkeSessionParams.Builder(context) .setServerHostname(profile.getServerAddr()) .setNetwork(network) .setLocalIdentification(localId) .setRemoteIdentification(remoteId); setIkeAuth(profile, ikeOptionsBuilder); for (final IkeSaProposal ikeProposal : getIkeSaProposals()) { ikeOptionsBuilder.addSaProposal(ikeProposal); } return ikeOptionsBuilder.build(); } static ChildSessionParams buildChildSessionParams(List allowedAlgorithms) { final TunnelModeChildSessionParams.Builder childOptionsBuilder = new TunnelModeChildSessionParams.Builder(); for (final ChildSaProposal childProposal : getChildSaProposals(allowedAlgorithms)) { childOptionsBuilder.addSaProposal(childProposal); } childOptionsBuilder.addInternalAddressRequest(OsConstants.AF_INET); childOptionsBuilder.addInternalAddressRequest(OsConstants.AF_INET6); childOptionsBuilder.addInternalDnsServerRequest(OsConstants.AF_INET); childOptionsBuilder.addInternalDnsServerRequest(OsConstants.AF_INET6); return childOptionsBuilder.build(); } private static void setIkeAuth( @NonNull Ikev2VpnProfile profile, @NonNull IkeSessionParams.Builder builder) { switch (profile.getType()) { case VpnProfile.TYPE_IKEV2_IPSEC_USER_PASS: final EapSessionConfig eapConfig = new EapSessionConfig.Builder() .setEapMsChapV2Config(profile.getUsername(), profile.getPassword()) .build(); builder.setAuthEap(profile.getServerRootCaCert(), eapConfig); break; case VpnProfile.TYPE_IKEV2_IPSEC_PSK: builder.setAuthPsk(profile.getPresharedKey()); break; case VpnProfile.TYPE_IKEV2_IPSEC_RSA: builder.setAuthDigitalSignature( profile.getServerRootCaCert(), profile.getUserCert(), profile.getRsaPrivateKey()); break; default: throw new IllegalArgumentException("Unknown auth method set"); } } private static List getIkeSaProposals() { // TODO: Add ability to filter this when IKEv2 API is made Public API final List proposals = new ArrayList<>(); // Encryption Algorithms: Currently only AES_CBC is supported. final IkeSaProposal.Builder normalModeBuilder = new IkeSaProposal.Builder(); // Currently only AES_CBC is supported. normalModeBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_CBC, KEY_LEN_AES_256); normalModeBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_CBC, KEY_LEN_AES_192); normalModeBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_CBC, KEY_LEN_AES_128); // Authentication/Integrity Algorithms normalModeBuilder.addIntegrityAlgorithm(INTEGRITY_ALGORITHM_HMAC_SHA2_512_256); normalModeBuilder.addIntegrityAlgorithm(INTEGRITY_ALGORITHM_HMAC_SHA2_384_192); normalModeBuilder.addIntegrityAlgorithm(INTEGRITY_ALGORITHM_HMAC_SHA2_256_128); normalModeBuilder.addIntegrityAlgorithm(INTEGRITY_ALGORITHM_AES_XCBC_96); // Add AEAD options final IkeSaProposal.Builder aeadBuilder = new IkeSaProposal.Builder(); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_16, KEY_LEN_AES_256); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_12, KEY_LEN_AES_256); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_8, KEY_LEN_AES_256); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_16, KEY_LEN_AES_192); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_12, KEY_LEN_AES_192); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_8, KEY_LEN_AES_192); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_16, KEY_LEN_AES_128); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_12, KEY_LEN_AES_128); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_8, KEY_LEN_AES_128); // Add dh, prf for both builders for (final IkeSaProposal.Builder builder : Arrays.asList(normalModeBuilder, aeadBuilder)) { builder.addDhGroup(DH_GROUP_4096_BIT_MODP); builder.addDhGroup(DH_GROUP_3072_BIT_MODP); builder.addDhGroup(DH_GROUP_2048_BIT_MODP); builder.addPseudorandomFunction(PSEUDORANDOM_FUNCTION_AES128_XCBC); builder.addPseudorandomFunction(PSEUDORANDOM_FUNCTION_HMAC_SHA1); } proposals.add(normalModeBuilder.build()); proposals.add(aeadBuilder.build()); return proposals; } /** Builds a child SA proposal based on the allowed IPsec algorithms */ private static List getChildSaProposals(List allowedAlgorithms) { final List proposals = new ArrayList<>(); // Add non-AEAD options if (Ikev2VpnProfile.hasNormalModeAlgorithms(allowedAlgorithms)) { final ChildSaProposal.Builder normalModeBuilder = new ChildSaProposal.Builder(); // Encryption Algorithms: // AES-CBC is currently the only supported encryption algorithm. normalModeBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_CBC, KEY_LEN_AES_256); normalModeBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_CBC, KEY_LEN_AES_192); normalModeBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_CBC, KEY_LEN_AES_128); // Authentication/Integrity Algorithms: // Guaranteed by Ikev2VpnProfile constructor to contain at least one of these. if (allowedAlgorithms.contains(IpSecAlgorithm.AUTH_HMAC_SHA512)) { normalModeBuilder.addIntegrityAlgorithm(INTEGRITY_ALGORITHM_HMAC_SHA2_512_256); } if (allowedAlgorithms.contains(IpSecAlgorithm.AUTH_HMAC_SHA384)) { normalModeBuilder.addIntegrityAlgorithm(INTEGRITY_ALGORITHM_HMAC_SHA2_384_192); } if (allowedAlgorithms.contains(IpSecAlgorithm.AUTH_HMAC_SHA256)) { normalModeBuilder.addIntegrityAlgorithm(INTEGRITY_ALGORITHM_HMAC_SHA2_256_128); } ChildSaProposal proposal = normalModeBuilder.build(); if (proposal.getIntegrityAlgorithms().isEmpty()) { // Should be impossible; Verified in Ikev2VpnProfile. Log.wtf(TAG, "Missing integrity algorithm when buildling Child SA proposal"); } else { proposals.add(normalModeBuilder.build()); } } // Add AEAD options if (Ikev2VpnProfile.hasAeadAlgorithms(allowedAlgorithms)) { final ChildSaProposal.Builder aeadBuilder = new ChildSaProposal.Builder(); // AES-GCM is currently the only supported AEAD algorithm aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_16, KEY_LEN_AES_256); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_12, KEY_LEN_AES_256); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_8, KEY_LEN_AES_256); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_16, KEY_LEN_AES_192); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_12, KEY_LEN_AES_192); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_8, KEY_LEN_AES_192); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_16, KEY_LEN_AES_128); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_12, KEY_LEN_AES_128); aeadBuilder.addEncryptionAlgorithm(ENCRYPTION_ALGORITHM_AES_GCM_8, KEY_LEN_AES_128); proposals.add(aeadBuilder.build()); } return proposals; } static class IkeSessionCallbackImpl implements IkeSessionCallback { private final String mTag; private final Vpn.IkeV2VpnRunnerCallback mCallback; private final Network mNetwork; IkeSessionCallbackImpl(String tag, Vpn.IkeV2VpnRunnerCallback callback, Network network) { mTag = tag; mCallback = callback; mNetwork = network; } @Override public void onOpened(@NonNull IkeSessionConfiguration ikeSessionConfig) { Log.d(mTag, "IkeOpened for network " + mNetwork); // Nothing to do here. } @Override public void onClosed() { Log.d(mTag, "IkeClosed for network " + mNetwork); mCallback.onSessionLost(mNetwork); // Server requested session closure. Retry? } @Override public void onClosedExceptionally(@NonNull IkeException exception) { Log.d(mTag, "IkeClosedExceptionally for network " + mNetwork, exception); mCallback.onSessionLost(mNetwork); } @Override public void onError(@NonNull IkeProtocolException exception) { Log.d(mTag, "IkeError for network " + mNetwork, exception); // Non-fatal, log and continue. } } static class ChildSessionCallbackImpl implements ChildSessionCallback { private final String mTag; private final Vpn.IkeV2VpnRunnerCallback mCallback; private final Network mNetwork; ChildSessionCallbackImpl(String tag, Vpn.IkeV2VpnRunnerCallback callback, Network network) { mTag = tag; mCallback = callback; mNetwork = network; } @Override public void onOpened(@NonNull ChildSessionConfiguration childConfig) { Log.d(mTag, "ChildOpened for network " + mNetwork); mCallback.onChildOpened(mNetwork, childConfig); } @Override public void onClosed() { Log.d(mTag, "ChildClosed for network " + mNetwork); mCallback.onSessionLost(mNetwork); } @Override public void onClosedExceptionally(@NonNull IkeException exception) { Log.d(mTag, "ChildClosedExceptionally for network " + mNetwork, exception); mCallback.onSessionLost(mNetwork); } @Override public void onIpSecTransformCreated(@NonNull IpSecTransform transform, int direction) { Log.d(mTag, "ChildTransformCreated; Direction: " + direction + "; network " + mNetwork); mCallback.onChildTransformCreated(mNetwork, transform, direction); } @Override public void onIpSecTransformDeleted(@NonNull IpSecTransform transform, int direction) { // Nothing to be done; no references to the IpSecTransform are held by the // Ikev2VpnRunner (or this callback class), and this transform will be closed by the // IKE library. Log.d(mTag, "ChildTransformDeleted; Direction: " + direction + "; for network " + mNetwork); } } static class Ikev2VpnNetworkCallback extends NetworkCallback { private final String mTag; private final Vpn.IkeV2VpnRunnerCallback mCallback; Ikev2VpnNetworkCallback(String tag, Vpn.IkeV2VpnRunnerCallback callback) { mTag = tag; mCallback = callback; } @Override public void onAvailable(@NonNull Network network) { Log.d(mTag, "Starting IKEv2/IPsec session on new network: " + network); mCallback.onDefaultNetworkChanged(network); } @Override public void onLost(@NonNull Network network) { Log.d(mTag, "Tearing down; lost network: " + network); mCallback.onSessionLost(network); } } /** * Identity parsing logic using similar logic to open source implementations of IKEv2 * *

This method does NOT support using type-prefixes (eg 'fqdn:' or 'keyid'), or ASN.1 encoded * identities. */ private static IkeIdentification parseIkeIdentification(@NonNull String identityStr) { // TODO: Add identity formatting to public API javadocs. if (identityStr.contains("@")) { if (identityStr.startsWith("@#")) { // KEY_ID final String hexStr = identityStr.substring(2); return new IkeKeyIdIdentification(HexDump.hexStringToByteArray(hexStr)); } else if (identityStr.startsWith("@@")) { // RFC822 (USER_FQDN) return new IkeRfc822AddrIdentification(identityStr.substring(2)); } else if (identityStr.startsWith("@")) { // FQDN return new IkeFqdnIdentification(identityStr.substring(1)); } else { // RFC822 (USER_FQDN) return new IkeRfc822AddrIdentification(identityStr); } } else if (InetAddresses.isNumericAddress(identityStr)) { final InetAddress addr = InetAddresses.parseNumericAddress(identityStr); if (addr instanceof Inet4Address) { // IPv4 return new IkeIpv4AddrIdentification((Inet4Address) addr); } else if (addr instanceof Inet6Address) { // IPv6 return new IkeIpv6AddrIdentification((Inet6Address) addr); } else { throw new IllegalArgumentException("IP version not supported"); } } else { if (identityStr.contains(":")) { // KEY_ID return new IkeKeyIdIdentification(identityStr.getBytes()); } else { // FQDN return new IkeFqdnIdentification(identityStr); } } } static Collection getRoutesFromTrafficSelectors( List trafficSelectors) { final HashSet routes = new HashSet<>(); for (final IkeTrafficSelector selector : trafficSelectors) { for (final IpPrefix prefix : new IpRange(selector.startingAddress, selector.endingAddress).asIpPrefixes()) { routes.add(new RouteInfo(prefix, null)); } } return routes; } }