diff --git a/netd/BpfHandler.cpp b/netd/BpfHandler.cpp
new file mode 100644
index 0000000..3cd5e13
--- /dev/null
+++ b/netd/BpfHandler.cpp
@@ -0,0 +1,212 @@
+/**
+ * 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.
+ */
+
+#define LOG_TAG "BpfHandler"
+
+#include "BpfHandler.h"
+
+#include <linux/bpf.h>
+
+#include <android-base/unique_fd.h>
+#include <bpf/WaitForProgsLoaded.h>
+#include <log/log.h>
+#include <netdutils/UidConstants.h>
+#include <private/android_filesystem_config.h>
+
+#include "BpfSyscallWrappers.h"
+
+namespace android {
+namespace net {
+
+using base::unique_fd;
+using bpf::NONEXISTENT_COOKIE;
+using bpf::getSocketCookie;
+using bpf::retrieveProgram;
+using netdutils::Status;
+using netdutils::statusFromErrno;
+
+constexpr int PER_UID_STATS_ENTRIES_LIMIT = 500;
+// At most 90% of the stats map may be used by tagged traffic entries. This ensures
+// that 10% of the map is always available to count untagged traffic, one entry per UID.
+// Otherwise, apps would be able to avoid data usage accounting entirely by filling up the
+// map with tagged traffic entries.
+constexpr int TOTAL_UID_STATS_ENTRIES_LIMIT = STATS_MAP_SIZE * 0.9;
+
+static_assert(STATS_MAP_SIZE - TOTAL_UID_STATS_ENTRIES_LIMIT > 100,
+              "The limit for stats map is to high, stats data may be lost due to overflow");
+
+static Status attachProgramToCgroup(const char* programPath, const unique_fd& cgroupFd,
+                                    bpf_attach_type type) {
+    unique_fd cgroupProg(retrieveProgram(programPath));
+    if (cgroupProg == -1) {
+        int ret = errno;
+        ALOGE("Failed to get program from %s: %s", programPath, strerror(ret));
+        return statusFromErrno(ret, "cgroup program get failed");
+    }
+    if (android::bpf::attachProgram(type, cgroupProg, cgroupFd)) {
+        int ret = errno;
+        ALOGE("Program from %s attach failed: %s", programPath, strerror(ret));
+        return statusFromErrno(ret, "program attach failed");
+    }
+    return netdutils::status::ok;
+}
+
+static Status initPrograms(const char* cg2_path) {
+    unique_fd cg_fd(open(cg2_path, O_DIRECTORY | O_RDONLY | O_CLOEXEC));
+    if (cg_fd == -1) {
+        int ret = errno;
+        ALOGE("Failed to open the cgroup directory: %s", strerror(ret));
+        return statusFromErrno(ret, "Open the cgroup directory failed");
+    }
+    RETURN_IF_NOT_OK(attachProgramToCgroup(BPF_EGRESS_PROG_PATH, cg_fd, BPF_CGROUP_INET_EGRESS));
+    RETURN_IF_NOT_OK(attachProgramToCgroup(BPF_INGRESS_PROG_PATH, cg_fd, BPF_CGROUP_INET_INGRESS));
+
+    // For the devices that support cgroup socket filter, the socket filter
+    // should be loaded successfully by bpfloader. So we attach the filter to
+    // cgroup if the program is pinned properly.
+    // TODO: delete the if statement once all devices should support cgroup
+    // socket filter (ie. the minimum kernel version required is 4.14).
+    if (!access(CGROUP_SOCKET_PROG_PATH, F_OK)) {
+        RETURN_IF_NOT_OK(
+                attachProgramToCgroup(CGROUP_SOCKET_PROG_PATH, cg_fd, BPF_CGROUP_INET_SOCK_CREATE));
+    }
+    return netdutils::status::ok;
+}
+
+BpfHandler::BpfHandler()
+    : mPerUidStatsEntriesLimit(PER_UID_STATS_ENTRIES_LIMIT),
+      mTotalUidStatsEntriesLimit(TOTAL_UID_STATS_ENTRIES_LIMIT) {}
+
+BpfHandler::BpfHandler(uint32_t perUidLimit, uint32_t totalLimit)
+    : mPerUidStatsEntriesLimit(perUidLimit), mTotalUidStatsEntriesLimit(totalLimit) {}
+
+Status BpfHandler::init(const char* cg2_path) {
+    // Make sure BPF programs are loaded before doing anything
+    android::bpf::waitForProgsLoaded();
+    ALOGI("BPF programs are loaded");
+
+    RETURN_IF_NOT_OK(initPrograms(cg2_path));
+    RETURN_IF_NOT_OK(initMaps());
+
+    return netdutils::status::ok;
+}
+
+Status BpfHandler::initMaps() {
+    std::lock_guard guard(mMutex);
+    RETURN_IF_NOT_OK(mCookieTagMap.init(COOKIE_TAG_MAP_PATH));
+    RETURN_IF_NOT_OK(mStatsMapA.init(STATS_MAP_A_PATH));
+    RETURN_IF_NOT_OK(mStatsMapB.init(STATS_MAP_B_PATH));
+    RETURN_IF_NOT_OK(mConfigurationMap.init(CONFIGURATION_MAP_PATH));
+    RETURN_IF_NOT_OK(mConfigurationMap.writeValue(CURRENT_STATS_MAP_CONFIGURATION_KEY, SELECT_MAP_A,
+                                                  BPF_ANY));
+    RETURN_IF_NOT_OK(mUidPermissionMap.init(UID_PERMISSION_MAP_PATH));
+
+    return netdutils::status::ok;
+}
+
+bool BpfHandler::hasUpdateDeviceStatsPermission(uid_t uid) {
+    // This implementation is the same logic as method ActivityManager#checkComponentPermission.
+    // It implies that the real uid can never be the same as PER_USER_RANGE.
+    uint32_t appId = uid % PER_USER_RANGE;
+    auto permission = mUidPermissionMap.readValue(appId);
+    if (permission.ok() && (permission.value() & BPF_PERMISSION_UPDATE_DEVICE_STATS)) {
+        return true;
+    }
+    return ((appId == AID_ROOT) || (appId == AID_SYSTEM) || (appId == AID_DNS));
+}
+
+int BpfHandler::tagSocket(int sockFd, uint32_t tag, uid_t chargeUid, uid_t realUid) {
+    std::lock_guard guard(mMutex);
+    if (chargeUid != realUid && !hasUpdateDeviceStatsPermission(realUid)) {
+        return -EPERM;
+    }
+
+    uint64_t sock_cookie = getSocketCookie(sockFd);
+    if (sock_cookie == NONEXISTENT_COOKIE) return -errno;
+    UidTagValue newKey = {.uid = (uint32_t)chargeUid, .tag = tag};
+
+    uint32_t totalEntryCount = 0;
+    uint32_t perUidEntryCount = 0;
+    // Now we go through the stats map and count how many entries are associated
+    // with chargeUid. If the uid entry hit the limit for each chargeUid, we block
+    // the request to prevent the map from overflow. It is safe here to iterate
+    // over the map since when mMutex is hold, system server cannot toggle
+    // the live stats map and clean it. So nobody can delete entries from the map.
+    const auto countUidStatsEntries = [chargeUid, &totalEntryCount, &perUidEntryCount](
+                                              const StatsKey& key,
+                                              const BpfMap<StatsKey, StatsValue>&) {
+        if (key.uid == chargeUid) {
+            perUidEntryCount++;
+        }
+        totalEntryCount++;
+        return base::Result<void>();
+    };
+    auto configuration = mConfigurationMap.readValue(CURRENT_STATS_MAP_CONFIGURATION_KEY);
+    if (!configuration.ok()) {
+        ALOGE("Failed to get current configuration: %s, fd: %d",
+              strerror(configuration.error().code()), mConfigurationMap.getMap().get());
+        return -configuration.error().code();
+    }
+    if (configuration.value() != SELECT_MAP_A && configuration.value() != SELECT_MAP_B) {
+        ALOGE("unknown configuration value: %d", configuration.value());
+        return -EINVAL;
+    }
+
+    BpfMap<StatsKey, StatsValue>& currentMap =
+            (configuration.value() == SELECT_MAP_A) ? mStatsMapA : mStatsMapB;
+    base::Result<void> res = currentMap.iterate(countUidStatsEntries);
+    if (!res.ok()) {
+        ALOGE("Failed to count the stats entry in map %d: %s", currentMap.getMap().get(),
+              strerror(res.error().code()));
+        return -res.error().code();
+    }
+
+    if (totalEntryCount > mTotalUidStatsEntriesLimit ||
+        perUidEntryCount > mPerUidStatsEntriesLimit) {
+        ALOGE("Too many stats entries in the map, total count: %u, chargeUid(%u) count: %u,"
+              " blocking tag request to prevent map overflow",
+              totalEntryCount, chargeUid, perUidEntryCount);
+        return -EMFILE;
+    }
+    // Update the tag information of a socket to the cookieUidMap. Use BPF_ANY
+    // flag so it will insert a new entry to the map if that value doesn't exist
+    // yet. And update the tag if there is already a tag stored. Since the eBPF
+    // program in kernel only read this map, and is protected by rcu read lock. It
+    // should be fine to cocurrently update the map while eBPF program is running.
+    res = mCookieTagMap.writeValue(sock_cookie, newKey, BPF_ANY);
+    if (!res.ok()) {
+        ALOGE("Failed to tag the socket: %s, fd: %d", strerror(res.error().code()),
+              mCookieTagMap.getMap().get());
+        return -res.error().code();
+    }
+    return 0;
+}
+
+int BpfHandler::untagSocket(int sockFd) {
+    std::lock_guard guard(mMutex);
+    uint64_t sock_cookie = getSocketCookie(sockFd);
+
+    if (sock_cookie == NONEXISTENT_COOKIE) return -errno;
+    base::Result<void> res = mCookieTagMap.deleteValue(sock_cookie);
+    if (!res.ok()) {
+        ALOGE("Failed to untag socket: %s\n", strerror(res.error().code()));
+        return -res.error().code();
+    }
+    return 0;
+}
+
+}  // namespace net
+}  // namespace android