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Commit 83e2e0e8 authored by Raphael Kim's avatar Raphael Kim
Browse files

[CDM] remove platform version exchange protocol 

Bug: 280846138
Test: Tested manually from raven (U) -> r11 (T)
Change-Id: I78d4b6cd334963d44e1081f97f190e83da8ea5ee
parent 0bdf223f

services/companion/java/com/android/server/companion/transport/CompanionTransportManager.java

+16 −105
Original line number Diff line number Diff line
@@ -19,10 +19,8 @@ package com.android.server.companion.transport; 
import static android.Manifest.permission.DELIVER_COMPANION_MESSAGES;



import static com.android.server.companion.transport.Transport.MESSAGE_REQUEST_PERMISSION_RESTORE;

import static com.android.server.companion.transport.Transport.MESSAGE_REQUEST_PLATFORM_INFO;



import android.annotation.NonNull;

import android.annotation.Nullable;

import android.annotation.SuppressLint;

import android.app.ActivityManagerInternal;

import android.companion.AssociationInfo;
@@ -33,7 +31,6 @@ import android.content.pm.ApplicationInfo; 
import android.content.pm.PackageManager.NameNotFoundException;

import android.os.Binder;

import android.os.Build;

import android.os.IBinder;

import android.os.ParcelFileDescriptor;

import android.os.RemoteCallbackList;

import android.os.RemoteException;
@@ -46,7 +43,6 @@ import com.android.server.companion.AssociationStore; 


import java.io.FileDescriptor;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.charset.StandardCharsets;

import java.util.ArrayList;

import java.util.List;
@@ -58,19 +54,8 @@ public class CompanionTransportManager { 
    private static final String TAG = "CDM_CompanionTransportManager";

    private static final boolean DEBUG = false;



    private static final int SECURE_CHANNEL_AVAILABLE_SDK = Build.VERSION_CODES.UPSIDE_DOWN_CAKE;

    private static final int NON_ANDROID = -1;



    private boolean mSecureTransportEnabled = true;



    private static boolean isRequest(int message) {

        return (message & 0xFF000000) == 0x63000000;

    }



    private static boolean isResponse(int message) {

        return (message & 0xFF000000) == 0x33000000;

    }



    private final Context mContext;

    private final AssociationStore mAssociationStore;
@@ -84,10 +69,6 @@ public class CompanionTransportManager { 
    @NonNull

    private final SparseArray<IOnMessageReceivedListener> mMessageListeners = new SparseArray<>();





    @Nullable

    private Transport mTempTransport;



    public CompanionTransportManager(Context context, AssociationStore associationStore) {

        mContext = context;

        mAssociationStore = associationStore;
@@ -199,7 +180,8 @@ public class CompanionTransportManager { 
                detachSystemDataTransport(packageName, userId, associationId);

            }



            initializeTransport(associationId, fd);

            // TODO: Implement new API to pass a PSK

            initializeTransport(associationId, fd, null);



            notifyOnTransportsChanged();

        }
@@ -237,107 +219,36 @@ public class CompanionTransportManager { 
        });

    }



    private void initializeTransport(int associationId, ParcelFileDescriptor fd) {

    private void initializeTransport(int associationId,

                                     ParcelFileDescriptor fd,

                                     byte[] preSharedKey) {

        Slog.i(TAG, "Initializing transport");

        Transport transport;

        if (!isSecureTransportEnabled()) {

            Transport transport = new RawTransport(associationId, fd, mContext);

            addMessageListenersToTransport(transport);

            transport.start();

            synchronized (mTransports) {

                mTransports.put(associationId, transport);

            }

            Slog.i(TAG, "RawTransport is created");

            return;

        }



        // Exchange platform info to decide which transport should be created

        mTempTransport = new RawTransport(associationId, fd, mContext);

        addMessageListenersToTransport(mTempTransport);

        IOnMessageReceivedListener listener = new IOnMessageReceivedListener() {

            @Override

            public void onMessageReceived(int associationId, byte[] data) throws RemoteException {

                synchronized (mTransports) {

                    onPlatformInfoReceived(associationId, data);

                }

            }



            @Override

            public IBinder asBinder() {

                return null;

            }

        };

        mTempTransport.addListener(MESSAGE_REQUEST_PLATFORM_INFO, listener);

        mTempTransport.start();



        int sdk = Build.VERSION.SDK_INT;

        String release = Build.VERSION.RELEASE;

        // data format: | SDK_INT (int) | release length (int) | release |

        final ByteBuffer data = ByteBuffer.allocate(4 + 4 + release.getBytes().length)

                .putInt(sdk)

                .putInt(release.getBytes().length)

                .put(release.getBytes());



        // TODO: it should check if preSharedKey is given

        try {

            mTempTransport.sendMessage(MESSAGE_REQUEST_PLATFORM_INFO, data.array());

        } catch (IOException e) {

            Slog.e(TAG, "Failed to exchange platform info");

        }

    }



    /**

     * Depending on the remote platform info to decide which transport should be created

     */

    private void onPlatformInfoReceived(int associationId, byte[] data) {

        if (mTempTransport.getAssociationId() != associationId) {

            return;

        }

        // TODO: it should check if preSharedKey is given



        ByteBuffer buffer = ByteBuffer.wrap(data);

        int remoteSdk = buffer.getInt();

        byte[] remoteRelease = new byte[buffer.getInt()];

        buffer.get(remoteRelease);



        Slog.i(TAG, "Remote device SDK: " + remoteSdk + ", release:" + new String(remoteRelease));



        Transport transport = mTempTransport;

        mTempTransport.stop();



        int sdk = Build.VERSION.SDK_INT;

        String release = Build.VERSION.RELEASE;



        if (sdk < SECURE_CHANNEL_AVAILABLE_SDK || remoteSdk < SECURE_CHANNEL_AVAILABLE_SDK) {

            // If either device is Android T or below, use raw channel

            // TODO: depending on the release version, either

            //       1) using a RawTransport for old T versions

            //       2) or an Ukey2 handshaked transport for UKey2 backported T versions

            Slog.d(TAG, "Secure channel is not supported. Using raw transport");

            transport = new RawTransport(transport.getAssociationId(), transport.getFd(), mContext);

            // If secure transport is explicitly disabled for testing, use raw transport

            Slog.i(TAG, "Secure channel is disabled. Creating raw transport");

            transport = new RawTransport(associationId, fd, mContext);

        } else if (Build.isDebuggable()) {

            // If device is debug build, use hardcoded test key for authentication

            Slog.d(TAG, "Creating an unauthenticated secure channel");

            final byte[] testKey = "CDM".getBytes(StandardCharsets.UTF_8);

            transport = new SecureTransport(transport.getAssociationId(), transport.getFd(),

                    mContext, testKey, null);

        } else if (sdk == NON_ANDROID || remoteSdk == NON_ANDROID) {

            transport = new SecureTransport(associationId, fd, mContext, testKey, null);

        } else if (preSharedKey != null) {

            // If either device is not Android, then use app-specific pre-shared key

            // TODO: pass in a real preSharedKey

            Slog.d(TAG, "Creating a PSK-authenticated secure channel");

            transport = new SecureTransport(transport.getAssociationId(), transport.getFd(),

                    mContext, new byte[0], null);

            transport = new SecureTransport(associationId, fd, mContext, preSharedKey, null);

        } else {

            // If none of the above applies, then use secure channel with attestation verification

            Slog.d(TAG, "Creating a secure channel");

            transport = new SecureTransport(transport.getAssociationId(), transport.getFd(),

                    mContext);

            transport = new SecureTransport(associationId, fd, mContext);

        }



        addMessageListenersToTransport(transport);

        transport.start();

        synchronized (mTransports) {

            mTransports.put(transport.getAssociationId(), transport);

            mTransports.put(associationId, transport);

        }

        // Doesn't need to notifyTransportsChanged here, it'll be done in attachSystemDataTransport



    }



    public Future<?> requestPermissionRestore(int associationId, byte[] data) {

services/companion/java/com/android/server/companion/transport/RawTransport.java

+3 −3
Original line number Diff line number Diff line
@@ -35,7 +35,7 @@ class RawTransport extends Transport { 
    }



    @Override

    public void start() {

    void start() {

        if (DEBUG) {

            Slog.d(TAG, "Starting raw transport.");

        }
@@ -54,7 +54,7 @@ class RawTransport extends Transport { 
    }



    @Override

    public void stop() {

    void stop() {

        if (DEBUG) {

            Slog.d(TAG, "Stopping raw transport.");

        }
@@ -62,7 +62,7 @@ class RawTransport extends Transport { 
    }



    @Override

    public void close() {

    void close() {

        stop();



        if (DEBUG) {

services/companion/java/com/android/server/companion/transport/SecureTransport.java

+3 −3
Original line number Diff line number Diff line
@@ -51,18 +51,18 @@ class SecureTransport extends Transport implements SecureChannel.Callback { 
    }



    @Override

    public void start() {

    void start() {

        mSecureChannel.start();

    }



    @Override

    public void stop() {

    void stop() {

        mSecureChannel.stop();

        mShouldProcessRequests = false;

    }



    @Override

    public void close() {

    void close() {

        mSecureChannel.close();

        mShouldProcessRequests = false;

    }

services/companion/java/com/android/server/companion/transport/Transport.java

+3 −9
Original line number Diff line number Diff line
@@ -47,7 +47,6 @@ public abstract class Transport { 
    protected static final boolean DEBUG = Build.IS_DEBUGGABLE;



    static final int MESSAGE_REQUEST_PING = 0x63807378; // ?PIN

    public static final int MESSAGE_REQUEST_PLATFORM_INFO = 0x63807073; // ?PFI

    public static final int MESSAGE_REQUEST_CONTEXT_SYNC = 0x63678883; // ?CXS

    public static final int MESSAGE_REQUEST_PERMISSION_RESTORE = 0x63826983; // ?RES
@@ -113,17 +112,17 @@ public abstract class Transport { 
    /**

     * Start listening to messages.

     */

    public abstract void start();

    abstract void start();



    /**

     * Soft stop listening to the incoming data without closing the streams.

     */

    public abstract void stop();

    abstract void stop();



    /**

     * Stop listening to the incoming data and close the streams.

     */

    public abstract void close();

    abstract void close();



    protected abstract void sendMessage(int message, int sequence, @NonNull byte[] data)

            throws IOException;
@@ -183,11 +182,6 @@ public abstract class Transport { 
                sendMessage(MESSAGE_RESPONSE_SUCCESS, sequence, data);

                break;

            }

            case MESSAGE_REQUEST_PLATFORM_INFO: {

                callback(message, data);

                // DO NOT SEND A RESPONSE!

                break;

            }

            case MESSAGE_REQUEST_CONTEXT_SYNC: {

                callback(message, data);

                sendMessage(MESSAGE_RESPONSE_SUCCESS, sequence, EmptyArray.BYTE);