Bpf Util Lib in Common Location

Add bpf lib to load and attach BPF programs in commonly accesible
location.

Bug: 179733303

Change-Id: I17b68abb14e816e7210bc603ffda44e10fb73d2f

staticlibs/Android.bp

@@ -112,6 +112,7 @@ java_library {
     srcs: [
         "device/com/android/net/module/util/BpfBitmap.java",
         "device/com/android/net/module/util/BpfMap.java",
+        "device/com/android/net/module/util/BpfUtils.java",
         "device/com/android/net/module/util/HexDump.java",
         "device/com/android/net/module/util/IBpfMap.java",
         "device/com/android/net/module/util/JniUtil.java",

staticlibs/device/com/android/net/module/util/BpfUtils.java

@@ -0,0 +1,69 @@
+/*
+ * 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.net.module.util;
+
+import androidx.annotation.NonNull;
+
+import java.io.IOException;
+
+/**
+ * The classes and the methods for BPF utilization.
+ *
+ * {@hide}
+ */
+public class BpfUtils {
+    static {
+        System.loadLibrary(JniUtil.getJniLibraryName(BpfUtils.class.getPackage()));
+    }
+
+    // Defined in include/uapi/linux/bpf.h. Only adding the CGROUPS currently being used for now.
+    public static final int BPF_CGROUP_INET_INGRESS = 0;
+    public static final int BPF_CGROUP_INET_EGRESS = 1;
+    public static final int BPF_CGROUP_INET4_BIND = 8;
+    public static final int BPF_CGROUP_INET6_BIND = 9;
+
+
+    /**
+     * Attach BPF program to CGROUP
+     */
+    public static void attachProgram(int type, @NonNull String programPath,
+            @NonNull String cgroupPath, int flags) throws IOException {
+        native_attachProgramToCgroup(type, programPath, cgroupPath, flags);
+    }
+
+    /**
+     * Detach BPF program from CGROUP
+     */
+    public static void detachProgram(int type, @NonNull String cgroupPath)
+            throws IOException {
+        native_detachProgramFromCgroup(type, cgroupPath);
+    }
+
+    /**
+     * Detach single BPF program from CGROUP
+     */
+    public static void detachSingleProgram(int type, @NonNull String programPath,
+            @NonNull String cgroupPath) throws IOException {
+        native_detachSingleProgramFromCgroup(type, programPath, cgroupPath);
+    }
+
+    private static native boolean native_attachProgramToCgroup(int type, String programPath,
+            String cgroupPath, int flags) throws IOException;
+    private static native boolean native_detachProgramFromCgroup(int type, String cgroupPath)
+            throws IOException;
+    private static native boolean native_detachSingleProgramFromCgroup(int type,
+            String programPath, String cgroupPath) throws IOException;
+}

staticlibs/native/bpfutiljni/Android.bp

@@ -0,0 +1,44 @@
+// 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 {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_library_static {
+    name: "libnet_utils_device_common_bpfutils",
+    srcs: ["com_android_net_module_util_BpfUtils.cpp"],
+    header_libs: [
+        "bpf_syscall_wrappers",
+        "jni_headers",
+    ],
+    shared_libs: [
+        "libbase",
+        "liblog",
+        "libnativehelper_compat_libc++",
+    ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-parameter",
+    ],
+    min_sdk_version: "30",
+    apex_available: [
+        "com.android.tethering",
+        "//apex_available:platform",
+    ],
+    visibility: [
+        "//packages/modules/Connectivity/service",
+    ],
+}

staticlibs/native/bpfutiljni/com_android_net_module_util_BpfUtils.cpp

@@ -0,0 +1,132 @@
+/*
+ * 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 <android-base/unique_fd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <jni.h>
+#include <nativehelper/JNIHelp.h>
+#include <nativehelper/ScopedLocalRef.h>
+#include <nativehelper/scoped_utf_chars.h>
+#include <string.h>
+#include <sys/socket.h>
+
+#include "BpfSyscallWrappers.h"
+
+namespace android {
+
+using base::unique_fd;
+
+// If attach fails throw error and return false.
+static jboolean com_android_net_module_util_BpfUtil_attachProgramToCgroup(JNIEnv *env,
+        jobject clazz, jint type, jstring bpfProgPath, jstring cgroupPath, jint flags) {
+
+    ScopedUtfChars dirPath(env, cgroupPath);
+    unique_fd cg_fd(open(dirPath.c_str(), O_DIRECTORY | O_RDONLY | O_CLOEXEC));
+    if (cg_fd == -1) {
+        jniThrowExceptionFmt(env, "java/io/IOException",
+                             "Failed to open the cgroup directory %s: %s",
+                             dirPath.c_str(), strerror(errno));
+        return false;
+    }
+
+    ScopedUtfChars bpfProg(env, bpfProgPath);
+    unique_fd bpf_fd(bpf::retrieveProgram(bpfProg.c_str()));
+    if (bpf_fd == -1) {
+        jniThrowExceptionFmt(env, "java/io/IOException",
+                             "Failed to retrieve bpf program from %s: %s",
+                             bpfProg.c_str(), strerror(errno));
+        return false;
+    }
+    if (bpf::attachProgram((bpf_attach_type) type, bpf_fd, cg_fd, flags)) {
+        jniThrowExceptionFmt(env, "java/io/IOException",
+                             "Failed to attach bpf program %s to %s: %s",
+                             bpfProg.c_str(), dirPath.c_str(), strerror(errno));
+        return false;
+    }
+    return true;
+}
+
+// If detach fails throw error and return false.
+static jboolean com_android_net_module_util_BpfUtil_detachProgramFromCgroup(JNIEnv *env,
+        jobject clazz, jint type, jstring cgroupPath) {
+
+    ScopedUtfChars dirPath(env, cgroupPath);
+    unique_fd cg_fd(open(dirPath.c_str(), O_DIRECTORY | O_RDONLY | O_CLOEXEC));
+    if (cg_fd == -1) {
+        jniThrowExceptionFmt(env, "java/io/IOException",
+                             "Failed to open the cgroup directory %s: %s",
+                             dirPath.c_str(), strerror(errno));
+        return false;
+    }
+
+    if (bpf::detachProgram((bpf_attach_type) type, cg_fd)) {
+        jniThrowExceptionFmt(env, "Failed to detach bpf program from %s: %s",
+                dirPath.c_str(), strerror(errno));
+        return false;
+    }
+    return true;
+}
+
+// If detach single program fails throw error and return false.
+static jboolean com_android_net_module_util_BpfUtil_detachSingleProgramFromCgroup(JNIEnv *env,
+        jobject clazz, jint type, jstring bpfProgPath, jstring cgroupPath) {
+
+    ScopedUtfChars dirPath(env, cgroupPath);
+    unique_fd cg_fd(open(dirPath.c_str(), O_DIRECTORY | O_RDONLY | O_CLOEXEC));
+    if (cg_fd == -1) {
+        jniThrowExceptionFmt(env, "java/io/IOException",
+                             "Failed to open the cgroup directory %s: %s",
+                             dirPath.c_str(), strerror(errno));
+        return false;
+    }
+
+    ScopedUtfChars bpfProg(env, bpfProgPath);
+    unique_fd bpf_fd(bpf::retrieveProgram(bpfProg.c_str()));
+    if (bpf_fd == -1) {
+        jniThrowExceptionFmt(env, "java/io/IOException",
+                             "Failed to retrieve bpf program from %s: %s",
+                             bpfProg.c_str(), strerror(errno));
+        return false;
+    }
+    if (bpf::detachSingleProgram((bpf_attach_type) type, bpf_fd, cg_fd)) {
+        jniThrowExceptionFmt(env, "Failed to detach bpf program %s from %s: %s",
+                bpfProg.c_str(), dirPath.c_str(), strerror(errno));
+        return false;
+    }
+    return true;
+}
+
+/*
+ * JNI registration.
+ */
+static const JNINativeMethod gMethods[] = {
+    /* name, signature, funcPtr */
+    { "native_attachProgramToCgroup", "(ILjava/lang/String;Ljava/lang/String;I)Z",
+        (void*) com_android_net_module_util_BpfUtil_attachProgramToCgroup },
+    { "native_detachProgramFromCgroup", "(ILjava/lang/String;)Z",
+        (void*) com_android_net_module_util_BpfUtil_detachProgramFromCgroup },
+    { "native_detachSingleProgramFromCgroup", "(ILjava/lang/String;Ljava/lang/String;)Z",
+        (void*) com_android_net_module_util_BpfUtil_detachSingleProgramFromCgroup },
+};
+
+int register_com_android_net_module_util_BpfUtils(JNIEnv* env, char const* class_name) {
+    return jniRegisterNativeMethods(env,
+            class_name,
+            gMethods, NELEM(gMethods));
+}
+
+}; // namespace android