Monitor interface added and update bpf interface map

Have BpfInterfaceMapUpdater to update bpf interface map: adding
the interface and index mapping to bpf interface map when interface
added.

Bug: 215095957
Test: atest FrameworkNetTests

Change-Id: I2189a50c4869cfc0c33fc6f0228f40ee9f3ac1d4

service-t/Sources.bp

@@ -26,6 +26,8 @@ filegroup {
     srcs: [
         "src/com/android/server/net/NetworkIdentity*.java",
         "src/com/android/server/net/NetworkStats*.java",
+        "src/com/android/server/net/BpfInterfaceMapUpdater.java",
+        "src/com/android/server/net/InterfaceMapValue.java",
     ],
     path: "src",
     visibility: [
@@ -97,3 +99,28 @@ filegroup {
         "//packages/modules/Connectivity:__subpackages__",
     ],
 }
+
+cc_library_shared {
+    name: "libcom_android_net_module_util_jni",
+    min_sdk_version: "30",
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-parameter",
+        "-Wthread-safety",
+    ],
+    srcs: [
+        "jni/onload.cpp",
+    ],
+    stl: "libc++_static",
+    static_libs: [
+        "libnet_utils_device_common_bpfjni",
+    ],
+    shared_libs: [
+        "liblog",
+        "libnativehelper",
+    ],
+    apex_available: [
+        "//apex_available:platform",
+    ],
+}

service-t/jni/onload.cpp

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+#include <nativehelper/JNIHelp.h>
+#include <log/log.h>
+
+namespace android {
+
+int register_com_android_net_module_util_BpfMap(JNIEnv* env, char const* class_name);
+
+extern "C" jint JNI_OnLoad(JavaVM* vm, void*) {
+    JNIEnv *env;
+    if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK) {
+        ALOGE("GetEnv failed");
+        return JNI_ERR;
+    }
+
+    if (register_com_android_net_module_util_BpfMap(env,
+            "com/android/net/module/util/BpfMap") < 0) return JNI_ERR;
+
+    return JNI_VERSION_1_6;
+}
+
+};
+

service-t/src/com/android/server/net/BpfInterfaceMapUpdater.java

@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2022 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.net;
+
+import android.content.Context;
+import android.net.INetd;
+import android.os.Handler;
+import android.os.IBinder;
+import android.os.RemoteException;
+import android.os.ServiceSpecificException;
+import android.system.ErrnoException;
+import android.util.Log;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.net.module.util.BaseNetdUnsolicitedEventListener;
+import com.android.net.module.util.BpfMap;
+import com.android.net.module.util.IBpfMap;
+import com.android.net.module.util.InterfaceParams;
+import com.android.net.module.util.Struct.U32;
+
+/**
+ * Monitor interface added (without removed) and right interface name and its index to bpf map.
+ */
+public class BpfInterfaceMapUpdater {
+    private static final String TAG = BpfInterfaceMapUpdater.class.getSimpleName();
+    // This is current path but may be changed soon.
+    private static final String IFACE_INDEX_NAME_MAP_PATH =
+            "/sys/fs/bpf/map_netd_iface_index_name_map";
+    private final IBpfMap<U32, InterfaceMapValue> mBpfMap;
+    private final INetd mNetd;
+    private final Handler mHandler;
+    private final Dependencies mDeps;
+
+    public BpfInterfaceMapUpdater(Context ctx, Handler handler) {
+        this(ctx, handler, new Dependencies());
+    }
+
+    @VisibleForTesting
+    public BpfInterfaceMapUpdater(Context ctx, Handler handler, Dependencies deps) {
+        mDeps = deps;
+        mBpfMap = deps.getInterfaceMap();
+        mNetd = deps.getINetd(ctx);
+        mHandler = handler;
+    }
+
+    /**
+     * Dependencies of BpfInerfaceMapUpdater, for injection in tests.
+     */
+    @VisibleForTesting
+    public static class Dependencies {
+        /** Create BpfMap for updating interface and index mapping. */
+        public IBpfMap<U32, InterfaceMapValue> getInterfaceMap() {
+            try {
+                return new BpfMap<>(IFACE_INDEX_NAME_MAP_PATH, BpfMap.BPF_F_RDWR,
+                    U32.class, InterfaceMapValue.class);
+            } catch (ErrnoException e) {
+                Log.e(TAG, "Cannot create interface map: " + e);
+                return null;
+            }
+        }
+
+        /** Get InterfaceParams for giving interface name. */
+        public InterfaceParams getInterfaceParams(String ifaceName) {
+            return InterfaceParams.getByName(ifaceName);
+        }
+
+        /** Get INetd binder object. */
+        public INetd getINetd(Context ctx) {
+            return INetd.Stub.asInterface((IBinder) ctx.getSystemService(Context.NETD_SERVICE));
+        }
+    }
+
+    /**
+     * Start listening interface update event.
+     * Query current interface names before listening.
+     */
+    public void start() {
+        mHandler.post(() -> {
+            if (mBpfMap == null) {
+                Log.wtf(TAG, "Fail to start: Null bpf map");
+                return;
+            }
+
+            try {
+                // TODO: use a NetlinkMonitor and listen for RTM_NEWLINK messages instead.
+                mNetd.registerUnsolicitedEventListener(new InterfaceChangeObserver());
+            } catch (RemoteException e) {
+                Log.wtf(TAG, "Unable to register netd UnsolicitedEventListener, " + e);
+            }
+
+            final String[] ifaces;
+            try {
+                // TODO: use a netlink dump to get the current interface list.
+                ifaces = mNetd.interfaceGetList();
+            } catch (RemoteException | ServiceSpecificException e) {
+                Log.wtf(TAG, "Unable to query interface names by netd, " + e);
+                return;
+            }
+
+            for (String ifaceName : ifaces) {
+                addInterface(ifaceName);
+            }
+        });
+    }
+
+    private void addInterface(String ifaceName) {
+        final InterfaceParams iface = mDeps.getInterfaceParams(ifaceName);
+        if (iface == null) {
+            Log.e(TAG, "Unable to get InterfaceParams for " + ifaceName);
+            return;
+        }
+
+        try {
+            mBpfMap.updateEntry(new U32(iface.index), new InterfaceMapValue(ifaceName));
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Unable to update entry for " + ifaceName + ", " + e);
+        }
+    }
+
+    private class InterfaceChangeObserver extends BaseNetdUnsolicitedEventListener {
+        @Override
+        public void onInterfaceAdded(String ifName) {
+            mHandler.post(() -> addInterface(ifName));
+        }
+    }
+}

service-t/src/com/android/server/net/InterfaceMapValue.java

@@ -0,0 +1,35 @@
+/*
+ * 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.net;
+
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.Struct.Field;
+import com.android.net.module.util.Struct.Type;
+
+/**
+ * The value of bpf interface index map which is used for NetworkStatsService.
+ */
+public class InterfaceMapValue extends Struct {
+    @Field(order = 0, type = Type.ByteArray, arraysize = 16)
+    public final byte[] interfaceName;
+
+    public InterfaceMapValue(String iface) {
+        final byte[] ifaceArray = iface.getBytes();
+        interfaceName = new byte[16];
+        // All array bytes after the interface name, if any, must be 0.
+        System.arraycopy(ifaceArray, 0, interfaceName, 0, ifaceArray.length);
+    }
+}

service-t/src/com/android/server/net/NetworkStatsService.java

@@ -356,6 +356,9 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     @NonNull
     private final LocationPermissionChecker mLocationPermissionChecker;
 
+    @NonNull
+    private final BpfInterfaceMapUpdater mInterfaceMapUpdater;
+
     private static @NonNull File getDefaultSystemDir() {
         return new File(Environment.getDataDirectory(), "system");
     }
@@ -453,6 +456,8 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         mContentObserver = mDeps.makeContentObserver(mHandler, mSettings,
                 mNetworkStatsSubscriptionsMonitor);
         mLocationPermissionChecker = mDeps.makeLocationPermissionChecker(mContext);
+        mInterfaceMapUpdater = mDeps.makeBpfInterfaceMapUpdater(mContext, mHandler);
+        mInterfaceMapUpdater.start();
     }
 
     /**
@@ -507,6 +512,13 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
         public LocationPermissionChecker makeLocationPermissionChecker(final Context context) {
             return new LocationPermissionChecker(context);
         }
+
+        /** Create BpfInterfaceMapUpdater to update bpf interface map. */
+        @NonNull
+        public BpfInterfaceMapUpdater makeBpfInterfaceMapUpdater(
+                @NonNull Context ctx, @NonNull Handler handler) {
+            return new BpfInterfaceMapUpdater(ctx, handler);
+        }
     }
 
     /**