bpfmap: Move to Common Util Location

Multiple packages need access to bpf maps. Moving to common
location to allow access from all necessary packages.

Test: atest BpfMapTest
Bug: 179733303

Change-Id: Idae7b620c15c781b2e7980c3a3157f396cfaf66e
diff --git a/staticlibs/native/bpf_syscall_wrappers/Android.bp b/staticlibs/native/bpf_syscall_wrappers/Android.bp
index 136342c..1416b6b 100644
--- a/staticlibs/native/bpf_syscall_wrappers/Android.bp
+++ b/staticlibs/native/bpf_syscall_wrappers/Android.bp
@@ -33,6 +33,7 @@
         "com.android.tethering",
     ],
     visibility: [
+        "//frameworks/libs/net/common/native/bpfmapjni",
         "//packages/modules/Connectivity/service",
         "//packages/modules/Connectivity/Tethering",
         "//system/bpf/libbpf_android",
diff --git a/staticlibs/native/bpfmapjni/Android.bp b/staticlibs/native/bpfmapjni/Android.bp
new file mode 100644
index 0000000..edbae7c
--- /dev/null
+++ b/staticlibs/native/bpfmapjni/Android.bp
@@ -0,0 +1,44 @@
+// Copyright (C) 2021 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: "libbpfmapjni",
+    srcs: ["com_android_net_module_util_BpfMap.cpp"],
+    header_libs: [
+        "bpf_syscall_wrappers",
+        "jni_headers",
+    ],
+    shared_libs: [
+        "liblog",
+        "libnativehelper_compat_libc++",
+    ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-parameter",
+    ],
+    sdk_version: "30",
+    min_sdk_version: "30",
+    apex_available: [
+        "com.android.tethering",
+        "//apex_available:platform",
+    ],
+    visibility: [
+        "//packages/modules/Connectivity/Tethering",
+    ],
+}
diff --git a/staticlibs/native/bpfmapjni/com_android_net_module_util_BpfMap.cpp b/staticlibs/native/bpfmapjni/com_android_net_module_util_BpfMap.cpp
new file mode 100644
index 0000000..e25e17d
--- /dev/null
+++ b/staticlibs/native/bpfmapjni/com_android_net_module_util_BpfMap.cpp
@@ -0,0 +1,136 @@
+/*
+ * 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.
+ */
+
+#include <errno.h>
+#include <jni.h>
+#include <nativehelper/JNIHelp.h>
+#include <nativehelper/ScopedLocalRef.h>
+
+#include "nativehelper/scoped_primitive_array.h"
+#include "nativehelper/scoped_utf_chars.h"
+
+#define BPF_FD_JUST_USE_INT
+#include "BpfSyscallWrappers.h"
+
+namespace android {
+
+static jint com_android_net_module_util_BpfMap_closeMap(JNIEnv *env, jobject clazz,
+        jint fd) {
+    int ret = close(fd);
+
+    if (ret) jniThrowErrnoException(env, "closeMap", errno);
+
+    return ret;
+}
+
+static jint com_android_net_module_util_BpfMap_bpfFdGet(JNIEnv *env, jobject clazz,
+        jstring path, jint mode) {
+    ScopedUtfChars pathname(env, path);
+
+    jint fd = bpf::bpfFdGet(pathname.c_str(), static_cast<unsigned>(mode));
+
+    if (fd < 0) jniThrowErrnoException(env, "bpfFdGet", errno);
+
+    return fd;
+}
+
+static void com_android_net_module_util_BpfMap_writeToMapEntry(JNIEnv *env, jobject clazz,
+        jint fd, jbyteArray key, jbyteArray value, jint flags) {
+    ScopedByteArrayRO keyRO(env, key);
+    ScopedByteArrayRO valueRO(env, value);
+
+    int ret = bpf::writeToMapEntry(static_cast<int>(fd), keyRO.get(), valueRO.get(),
+            static_cast<int>(flags));
+
+    if (ret) jniThrowErrnoException(env, "writeToMapEntry", errno);
+}
+
+static jboolean throwIfNotEnoent(JNIEnv *env, const char* functionName, int ret, int err) {
+    if (ret == 0) return true;
+
+    if (err != ENOENT) jniThrowErrnoException(env, functionName, err);
+    return false;
+}
+
+static jboolean com_android_net_module_util_BpfMap_deleteMapEntry(JNIEnv *env, jobject clazz,
+        jint fd, jbyteArray key) {
+    ScopedByteArrayRO keyRO(env, key);
+
+    // On success, zero is returned.  If the element is not found, -1 is returned and errno is set
+    // to ENOENT.
+    int ret = bpf::deleteMapEntry(static_cast<int>(fd), keyRO.get());
+
+    return throwIfNotEnoent(env, "deleteMapEntry", ret, errno);
+}
+
+static jboolean com_android_net_module_util_BpfMap_getNextMapKey(JNIEnv *env, jobject clazz,
+        jint fd, jbyteArray key, jbyteArray nextKey) {
+    // If key is found, the operation returns zero and sets the next key pointer to the key of the
+    // next element.  If key is not found, the operation returns zero and sets the next key pointer
+    // to the key of the first element.  If key is the last element, -1 is returned and errno is
+    // set to ENOENT.  Other possible errno values are ENOMEM, EFAULT, EPERM, and EINVAL.
+    ScopedByteArrayRW nextKeyRW(env, nextKey);
+    int ret;
+    if (key == nullptr) {
+        // Called by getFirstKey. Find the first key in the map.
+        ret = bpf::getNextMapKey(static_cast<int>(fd), nullptr, nextKeyRW.get());
+    } else {
+        ScopedByteArrayRO keyRO(env, key);
+        ret = bpf::getNextMapKey(static_cast<int>(fd), keyRO.get(), nextKeyRW.get());
+    }
+
+    return throwIfNotEnoent(env, "getNextMapKey", ret, errno);
+}
+
+static jboolean com_android_net_module_util_BpfMap_findMapEntry(JNIEnv *env, jobject clazz,
+        jint fd, jbyteArray key, jbyteArray value) {
+    ScopedByteArrayRO keyRO(env, key);
+    ScopedByteArrayRW valueRW(env, value);
+
+    // If an element is found, the operation returns zero and stores the element's value into
+    // "value".  If no element is found, the operation returns -1 and sets errno to ENOENT.
+    int ret = bpf::findMapEntry(static_cast<int>(fd), keyRO.get(), valueRW.get());
+
+    return throwIfNotEnoent(env, "findMapEntry", ret, errno);
+}
+
+/*
+ * JNI registration.
+ */
+static const JNINativeMethod gMethods[] = {
+    /* name, signature, funcPtr */
+    { "closeMap", "(I)I",
+        (void*) com_android_net_module_util_BpfMap_closeMap },
+    { "bpfFdGet", "(Ljava/lang/String;I)I",
+        (void*) com_android_net_module_util_BpfMap_bpfFdGet },
+    { "writeToMapEntry", "(I[B[BI)V",
+        (void*) com_android_net_module_util_BpfMap_writeToMapEntry },
+    { "deleteMapEntry", "(I[B)Z",
+        (void*) com_android_net_module_util_BpfMap_deleteMapEntry },
+    { "getNextMapKey", "(I[B[B)Z",
+        (void*) com_android_net_module_util_BpfMap_getNextMapKey },
+    { "findMapEntry", "(I[B[B)Z",
+        (void*) com_android_net_module_util_BpfMap_findMapEntry },
+
+};
+
+int register_com_android_net_module_util_BpfMap(JNIEnv* env, char const* class_name) {
+    return jniRegisterNativeMethods(env,
+            class_name,
+            gMethods, NELEM(gMethods));
+}
+
+}; // namespace android