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Commit b39f4d74 authored by Hungming Chen's avatar Hungming Chen
Browse files

[NFCT.NS.3] Add netfilter conntrack event monitor 

A preparation for starting monitoring conntrack event. Only the
netlink message header has been parsed for now. Need follow-up
commits to parse the netfilter message header and conntrack
attributes.

Test: atest TetheringCoverageTest
Change-Id: I71ca6cf75206fe8da7b5bb775b8debee6ab996b4
parent 3854f606

common/moduleutils/Android.bp

+1 −0
Original line number Original line Diff line number Diff line
@@ -50,6 +50,7 @@ filegroup { 
filegroup {

filegroup {

    name: "tethering-module-utils-srcs",

    name: "tethering-module-utils-srcs",

    srcs: [

    srcs: [

        "src/android/net/ip/ConntrackMonitor.java",

        "src/android/net/ip/InterfaceController.java",

        "src/android/net/ip/InterfaceController.java",

        "src/android/net/ip/IpNeighborMonitor.java",

        "src/android/net/ip/IpNeighborMonitor.java",

        "src/android/net/ip/NetlinkMonitor.java",

        "src/android/net/ip/NetlinkMonitor.java",

common/moduleutils/src/android/net/ip/ConntrackMonitor.java

0 → 100644
+79 −0
Original line number Original line Diff line number Diff line 
/*

 * 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 android.net.ip;



import android.net.netlink.ConntrackMessage;

import android.net.netlink.NetlinkMessage;

import android.net.util.SharedLog;

import android.os.Handler;

import android.system.OsConstants;



import androidx.annotation.NonNull;



/**

 * ConntrackMonitor.

 *

 * Monitors the netfilter conntrack notifications and presents to callers

 * ConntrackEvents describing each event.

 *

 * @hide

 */

public class ConntrackMonitor extends NetlinkMonitor {

    private static final String TAG = ConntrackMonitor.class.getSimpleName();

    private static final boolean DBG = false;

    private static final boolean VDBG = false;



    // Reference kernel/uapi/linux/netfilter/nfnetlink_compat.h

    public static final int NF_NETLINK_CONNTRACK_NEW = 1;

    public static final int NF_NETLINK_CONNTRACK_UPDATE = 2;

    public static final int NF_NETLINK_CONNTRACK_DESTROY = 4;



    /**

     * A class for describing parsed netfilter conntrack events.

     */

    public static class ConntrackEvent { /*TODO*/ }



    /**

     * A callback to caller for conntrack event.

     */

    public interface ConntrackEventConsumer {

        /**

         * Every conntrack event received on the netlink socket is passed in

         * here.

         */

        void accept(@NonNull ConntrackEvent event);

    }



    private final ConntrackEventConsumer mConsumer;



    public ConntrackMonitor(@NonNull Handler h, @NonNull SharedLog log,

            @NonNull ConntrackEventConsumer cb) {

        super(h, log, TAG, OsConstants.NETLINK_NETFILTER, NF_NETLINK_CONNTRACK_NEW

                | NF_NETLINK_CONNTRACK_UPDATE | NF_NETLINK_CONNTRACK_DESTROY);

        mConsumer = cb;

    }



    @Override

    public void processNetlinkMessage(NetlinkMessage nlMsg, final long whenMs) {

        if (!(nlMsg instanceof ConntrackMessage)) {

            mLog.e("non-conntrack msg: " + nlMsg);

            return;

        }



        mConsumer.accept(new ConntrackEvent() /* TODO */);

    }

}

common/netlinkclient/src/android/net/netlink/ConntrackMessage.java

+23 −4
Original line number Original line Diff line number Diff line
@@ -39,9 +39,6 @@ import java.nio.ByteOrder; 
public class ConntrackMessage extends NetlinkMessage {

public class ConntrackMessage extends NetlinkMessage {

    public static final int STRUCT_SIZE = StructNlMsgHdr.STRUCT_SIZE + StructNfGenMsg.STRUCT_SIZE;

    public static final int STRUCT_SIZE = StructNlMsgHdr.STRUCT_SIZE + StructNfGenMsg.STRUCT_SIZE;





    public static final short NFNL_SUBSYS_CTNETLINK = 1;

    public static final short IPCTNL_MSG_CT_NEW = 0;



    // enum ctattr_type

    // enum ctattr_type

    public static final short CTA_TUPLE_ORIG  = 1;

    public static final short CTA_TUPLE_ORIG  = 1;

    public static final short CTA_TUPLE_REPLY = 2;

    public static final short CTA_TUPLE_REPLY = 2;
@@ -84,7 +81,8 @@ public class ConntrackMessage extends NetlinkMessage { 




        final ConntrackMessage ctmsg = new ConntrackMessage();

        final ConntrackMessage ctmsg = new ConntrackMessage();

        ctmsg.mHeader.nlmsg_len = bytes.length;

        ctmsg.mHeader.nlmsg_len = bytes.length;

        ctmsg.mHeader.nlmsg_type = (NFNL_SUBSYS_CTNETLINK << 8) | IPCTNL_MSG_CT_NEW;

        ctmsg.mHeader.nlmsg_type = (NetlinkConstants.NFNL_SUBSYS_CTNETLINK << 8)

                | NetlinkConstants.IPCTNL_MSG_CT_NEW;

        ctmsg.mHeader.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_REPLACE;

        ctmsg.mHeader.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_REPLACE;

        ctmsg.mHeader.nlmsg_seq = 1;

        ctmsg.mHeader.nlmsg_seq = 1;

        ctmsg.pack(byteBuffer);

        ctmsg.pack(byteBuffer);
@@ -95,6 +93,22 @@ public class ConntrackMessage extends NetlinkMessage { 
        return bytes;

        return bytes;

    }

    }





    /**

     * Parses a netfilter conntrack message from a {@link ByteBuffer}.

     *

     * @param header the netlink message header.

     * @param byteBuffer The buffer from which to parse the netfilter conntrack message.

     * @return the parsed netfilter conntrack message, or {@code null} if the netfilter conntrack

     *         message could not be parsed successfully (for example, if it was truncated).

     */

    public static ConntrackMessage parse(StructNlMsgHdr header, ByteBuffer byteBuffer) {

        // Just build the netlink header for now and pretend the whole message was consumed.

        // TODO: Parse the netfilter message header and conntrack attributes.

        final ConntrackMessage conntrackMsg = new ConntrackMessage(header);

        byteBuffer.position(byteBuffer.limit());

        return conntrackMsg;

    }



    protected StructNfGenMsg mNfGenMsg;

    protected StructNfGenMsg mNfGenMsg;





    private ConntrackMessage() {

    private ConntrackMessage() {
@@ -102,6 +116,11 @@ public class ConntrackMessage extends NetlinkMessage { 
        mNfGenMsg = new StructNfGenMsg((byte) OsConstants.AF_INET);

        mNfGenMsg = new StructNfGenMsg((byte) OsConstants.AF_INET);

    }

    }





    private ConntrackMessage(StructNlMsgHdr header) {

        super(header);

        mNfGenMsg = null;

    }



    public void pack(ByteBuffer byteBuffer) {

    public void pack(ByteBuffer byteBuffer) {

        mHeader.pack(byteBuffer);

        mHeader.pack(byteBuffer);

        mNfGenMsg.pack(byteBuffer);

        mNfGenMsg.pack(byteBuffer);

common/netlinkclient/src/android/net/netlink/NetlinkConstants.java

+68 −27
Original line number Original line Diff line number Diff line
@@ -27,8 +27,10 @@ import java.nio.ByteBuffer; 
 *

 *

 * Values taken from:

 * Values taken from:

 *

 *

 *     &lt;linux_src&gt;/include/uapi/linux/netlink.h

 *     include/uapi/linux/netfilter/nfnetlink.h

 *     &lt;linux_src&gt;/include/uapi/linux/rtnetlink.h

 *     include/uapi/linux/netfilter/nfnetlink_conntrack.h

 *     include/uapi/linux/netlink.h

 *     include/uapi/linux/rtnetlink.h

 *

 *

 * @hide

 * @hide

 */

 */
@@ -104,7 +106,21 @@ public class NetlinkConstants { 
    public static final short RTM_GETRULE                   = 34;

    public static final short RTM_GETRULE                   = 34;

    public static final short RTM_NEWNDUSEROPT              = 68;

    public static final short RTM_NEWNDUSEROPT              = 68;





    /* see &lt;linux_src&gt;/include/uapi/linux/sock_diag.h */

    // Netfilter netlink message types are presented by two bytes: high byte subsystem and

    // low byte operation. See the macro NFNL_SUBSYS_ID and NFNL_MSG_TYPE in

    // include/uapi/linux/netfilter/nfnetlink.h

    public static final short NFNL_SUBSYS_CTNETLINK         = 1;



    public static final short IPCTNL_MSG_CT_NEW             = 0;

    public static final short IPCTNL_MSG_CT_GET             = 1;

    public static final short IPCTNL_MSG_CT_DELETE          = 2;

    public static final short IPCTNL_MSG_CT_GET_CTRZERO     = 3;

    public static final short IPCTNL_MSG_CT_GET_STATS_CPU   = 4;

    public static final short IPCTNL_MSG_CT_GET_STATS       = 5;

    public static final short IPCTNL_MSG_CT_GET_DYING       = 6;

    public static final short IPCTNL_MSG_CT_GET_UNCONFIRMED = 7;



    /* see include/uapi/linux/sock_diag.h */

    public static final short SOCK_DIAG_BY_FAMILY = 20;

    public static final short SOCK_DIAG_BY_FAMILY = 20;





    // Netlink groups.

    // Netlink groups.
@@ -163,6 +179,30 @@ public class NetlinkConstants { 
        }

        }

    }

    }





    /**

     * Convert a netlink message type to a string for NETLINK_NETFILTER.

     */

    @NonNull

    private static String stringForNfMsgType(short nlmType) {

        final byte subsysId = (byte) (nlmType >> 8);

        final byte msgType = (byte) nlmType;

        switch (subsysId) {

            case NFNL_SUBSYS_CTNETLINK:

                switch (msgType) {

                    case IPCTNL_MSG_CT_NEW: return "IPCTNL_MSG_CT_NEW";

                    case IPCTNL_MSG_CT_GET: return "IPCTNL_MSG_CT_GET";

                    case IPCTNL_MSG_CT_DELETE: return "IPCTNL_MSG_CT_DELETE";

                    case IPCTNL_MSG_CT_GET_CTRZERO: return "IPCTNL_MSG_CT_GET_CTRZERO";

                    case IPCTNL_MSG_CT_GET_STATS_CPU: return "IPCTNL_MSG_CT_GET_STATS_CPU";

                    case IPCTNL_MSG_CT_GET_STATS: return "IPCTNL_MSG_CT_GET_STATS";

                    case IPCTNL_MSG_CT_GET_DYING: return "IPCTNL_MSG_CT_GET_DYING";

                    case IPCTNL_MSG_CT_GET_UNCONFIRMED: return "IPCTNL_MSG_CT_GET_UNCONFIRMED";

                }

                break;

        }

        return "unknown NETFILTER type: " + String.valueOf(nlmType);

    }



    /**

    /**

     * Convert a netlink message type to a string by netlink family.

     * Convert a netlink message type to a string by netlink family.

     */

     */
@@ -177,6 +217,7 @@ public class NetlinkConstants { 
        // not constant.

        // not constant.

        if (nlFamily == OsConstants.NETLINK_ROUTE) return stringForRtMsgType(nlmType);

        if (nlFamily == OsConstants.NETLINK_ROUTE) return stringForRtMsgType(nlmType);

        if (nlFamily == OsConstants.NETLINK_INET_DIAG) return stringForInetDiagMsgType(nlmType);

        if (nlFamily == OsConstants.NETLINK_INET_DIAG) return stringForInetDiagMsgType(nlmType);

        if (nlFamily == OsConstants.NETLINK_NETFILTER) return stringForNfMsgType(nlmType);





        return "unknown type: " + String.valueOf(nlmType);

        return "unknown type: " + String.valueOf(nlmType);

    }

    }

common/netlinkclient/src/android/net/netlink/NetlinkMessage.java

+16 −0
Original line number Original line Diff line number Diff line
@@ -74,6 +74,9 @@ public class NetlinkMessage { 
        if (nlFamily == OsConstants.NETLINK_INET_DIAG) {

        if (nlFamily == OsConstants.NETLINK_INET_DIAG) {

            return parseInetDiagMessage(nlmsghdr, byteBuffer);

            return parseInetDiagMessage(nlmsghdr, byteBuffer);

        }

        }

        if (nlFamily == OsConstants.NETLINK_NETFILTER) {

            return parseNfMessage(nlmsghdr, byteBuffer);

        }





        return null;

        return null;

    }

    }
@@ -136,4 +139,17 @@ public class NetlinkMessage { 
            default: return null;

            default: return null;

        }

        }

    }

    }



    @Nullable

    private static NetlinkMessage parseNfMessage(@NonNull StructNlMsgHdr nlmsghdr,

            @NonNull ByteBuffer byteBuffer) {

        switch (nlmsghdr.nlmsg_type) {

            case NetlinkConstants.NFNL_SUBSYS_CTNETLINK << 8

                    | NetlinkConstants.IPCTNL_MSG_CT_NEW:

            case NetlinkConstants.NFNL_SUBSYS_CTNETLINK << 8

                    | NetlinkConstants.IPCTNL_MSG_CT_DELETE:

                return (NetlinkMessage) ConntrackMessage.parse(nlmsghdr, byteBuffer);

            default: return null;

        }

    }

}
 
}