diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 145eade..d2c0e18 100644
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -126,6 +126,7 @@
 import android.net.ConnectivitySettingsManager;
 import android.net.DataStallReportParcelable;
 import android.net.DnsResolverServiceManager;
+import android.net.DscpPolicy;
 import android.net.ICaptivePortal;
 import android.net.IConnectivityDiagnosticsCallback;
 import android.net.IConnectivityManager;
@@ -220,6 +221,7 @@
 import android.os.UserManager;
 import android.provider.Settings;
 import android.sysprop.NetworkProperties;
+import android.system.ErrnoException;
 import android.telephony.TelephonyManager;
 import android.text.TextUtils;
 import android.util.ArrayMap;
@@ -250,6 +252,7 @@
 import com.android.server.connectivity.ConnectivityFlags;
 import com.android.server.connectivity.DnsManager;
 import com.android.server.connectivity.DnsManager.PrivateDnsValidationUpdate;
+import com.android.server.connectivity.DscpPolicyTracker;
 import com.android.server.connectivity.FullScore;
 import com.android.server.connectivity.KeepaliveTracker;
 import com.android.server.connectivity.LingerMonitor;
@@ -389,6 +392,7 @@
     protected IDnsResolver mDnsResolver;
     @VisibleForTesting
     protected INetd mNetd;
+    private DscpPolicyTracker mDscpPolicyTracker = null;
     private NetworkStatsManager mStatsManager;
     private NetworkPolicyManager mPolicyManager;
     private final NetdCallback mNetdCallback;
@@ -1489,6 +1493,12 @@
                 new NetworkScore.Builder().setLegacyInt(0).build(), mContext, null,
                 new NetworkAgentConfig(), this, null, null, 0, INVALID_UID,
                 mLingerDelayMs, mQosCallbackTracker, mDeps);
+
+        try {
+            mDscpPolicyTracker = new DscpPolicyTracker();
+        } catch (ErrnoException e) {
+            loge("Unable to create DscpPolicyTracker");
+        }
     }
 
     private static NetworkCapabilities createDefaultNetworkCapabilitiesForUid(int uid) {
@@ -3406,6 +3416,25 @@
                     nai.setLingerDuration((int) arg.second);
                     break;
                 }
+                case NetworkAgent.EVENT_ADD_DSCP_POLICY: {
+                    DscpPolicy policy = (DscpPolicy) arg.second;
+                    if (mDscpPolicyTracker != null) {
+                        mDscpPolicyTracker.addDscpPolicy(nai, policy);
+                    }
+                    break;
+                }
+                case NetworkAgent.EVENT_REMOVE_DSCP_POLICY: {
+                    if (mDscpPolicyTracker != null) {
+                        mDscpPolicyTracker.removeDscpPolicy(nai, (int) arg.second);
+                    }
+                    break;
+                }
+                case NetworkAgent.EVENT_REMOVE_ALL_DSCP_POLICIES: {
+                    if (mDscpPolicyTracker != null) {
+                        mDscpPolicyTracker.removeAllDscpPolicies(nai);
+                    }
+                    break;
+                }
             }
         }
 
diff --git a/service/src/com/android/server/connectivity/DscpPolicyTracker.java b/service/src/com/android/server/connectivity/DscpPolicyTracker.java
new file mode 100644
index 0000000..0512a44
--- /dev/null
+++ b/service/src/com/android/server/connectivity/DscpPolicyTracker.java
@@ -0,0 +1,275 @@
+/*
+ * 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 com.android.server.connectivity;
+
+import static android.net.DscpPolicy.STATUS_DELETED;
+import static android.net.DscpPolicy.STATUS_INSUFFICIENT_PROCESSING_RESOURCES;
+import static android.net.DscpPolicy.STATUS_POLICY_NOT_FOUND;
+import static android.net.DscpPolicy.STATUS_SUCCESS;
+import static android.system.OsConstants.ETH_P_ALL;
+
+import android.annotation.NonNull;
+import android.net.DscpPolicy;
+import android.os.RemoteException;
+import android.system.ErrnoException;
+import android.util.Log;
+import android.util.SparseIntArray;
+
+import com.android.net.module.util.BpfMap;
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.TcUtils;
+
+import java.io.IOException;
+import java.net.Inet4Address;
+import java.net.Inet6Address;
+import java.net.NetworkInterface;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * DscpPolicyTracker has a single entry point from ConnectivityService handler.
+ * This guarantees that all code runs on the same thread and no locking is needed.
+ */
+public class DscpPolicyTracker {
+    static {
+        System.loadLibrary("com_android_connectivity_com_android_net_module_util_jni");
+    }
+
+    // After tethering and clat priorities.
+    static final short PRIO_DSCP = 5;
+
+    private static final String TAG = DscpPolicyTracker.class.getSimpleName();
+    private static final String PROG_PATH =
+            "/sys/fs/bpf/prog_dscp_policy_schedcls_set_dscp";
+    // Name is "map + *.o + map_name + map". Can probably shorten this
+    private static final String IPV4_POLICY_MAP_PATH = makeMapPath(
+            "dscp_policy_ipv4_dscp_policies");
+    private static final String IPV6_POLICY_MAP_PATH = makeMapPath(
+            "dscp_policy_ipv6_dscp_policies");
+    private static final int MAX_POLICIES = 16;
+
+    private static String makeMapPath(String which) {
+        return "/sys/fs/bpf/map_" + which + "_map";
+    }
+
+    private Set<String> mAttachedIfaces;
+
+    private final BpfMap<Struct.U32, DscpPolicyValue> mBpfDscpIpv4Policies;
+    private final BpfMap<Struct.U32, DscpPolicyValue> mBpfDscpIpv6Policies;
+    private final SparseIntArray mPolicyIdToBpfMapIndex;
+
+    public DscpPolicyTracker() throws ErrnoException {
+        mAttachedIfaces = new HashSet<String>();
+
+        mPolicyIdToBpfMapIndex = new SparseIntArray(MAX_POLICIES);
+        mBpfDscpIpv4Policies = new BpfMap<Struct.U32, DscpPolicyValue>(IPV4_POLICY_MAP_PATH,
+                BpfMap.BPF_F_RDWR, Struct.U32.class, DscpPolicyValue.class);
+        mBpfDscpIpv6Policies = new BpfMap<Struct.U32, DscpPolicyValue>(IPV6_POLICY_MAP_PATH,
+                BpfMap.BPF_F_RDWR, Struct.U32.class, DscpPolicyValue.class);
+    }
+
+    private int getFirstFreeIndex() {
+        for (int i = 0; i < MAX_POLICIES; i++) {
+            if (mPolicyIdToBpfMapIndex.indexOfValue(i) < 0) return i;
+        }
+        return MAX_POLICIES;
+    }
+
+    private void sendStatus(NetworkAgentInfo nai, int policyId, int status) {
+        try {
+            nai.networkAgent.onDscpPolicyStatusUpdated(policyId, status);
+        } catch (RemoteException e) {
+            Log.d(TAG, "Failed update policy status: ", e);
+        }
+    }
+
+    private boolean matchesIpv4(DscpPolicy policy) {
+        return ((policy.getDestinationAddress() == null
+                       || policy.getDestinationAddress() instanceof Inet4Address)
+            && (policy.getSourceAddress() == null
+                        || policy.getSourceAddress() instanceof Inet4Address));
+    }
+
+    private boolean matchesIpv6(DscpPolicy policy) {
+        return ((policy.getDestinationAddress() == null
+                       || policy.getDestinationAddress() instanceof Inet6Address)
+            && (policy.getSourceAddress() == null
+                        || policy.getSourceAddress() instanceof Inet6Address));
+    }
+
+    private int addDscpPolicyInternal(DscpPolicy policy) {
+        // If there is no existing policy with a matching ID, and we are already at
+        // the maximum number of policies then return INSUFFICIENT_PROCESSING_RESOURCES.
+        final int existingIndex = mPolicyIdToBpfMapIndex.get(policy.getPolicyId(), -1);
+        if (existingIndex == -1 && mPolicyIdToBpfMapIndex.size() >= MAX_POLICIES) {
+            return STATUS_INSUFFICIENT_PROCESSING_RESOURCES;
+        }
+
+        // Currently all classifiers are supported, if any are removed return
+        // STATUS_REQUESTED_CLASSIFIER_NOT_SUPPORTED,
+        // and for any other generic error STATUS_REQUEST_DECLINED
+
+        int addIndex = 0;
+        // If a policy with a matching ID exists, replace it, otherwise use the next free
+        // index for the policy.
+        if (existingIndex != -1) {
+            addIndex = mPolicyIdToBpfMapIndex.get(policy.getPolicyId());
+        } else {
+            addIndex = getFirstFreeIndex();
+        }
+
+        try {
+            mPolicyIdToBpfMapIndex.put(policy.getPolicyId(), addIndex);
+
+            // Add v4 policy to mBpfDscpIpv4Policies if source and destination address
+            // are both null or if they are both instances of Inet6Address.
+            if (matchesIpv4(policy)) {
+                mBpfDscpIpv4Policies.insertOrReplaceEntry(
+                        new Struct.U32(addIndex),
+                        new DscpPolicyValue(policy.getSourceAddress(),
+                            policy.getDestinationAddress(),
+                            policy.getSourcePort(), policy.getDestinationPortRange(),
+                            (short) policy.getProtocol(), (short) policy.getDscpValue()));
+            }
+
+            // Add v6 policy to mBpfDscpIpv6Policies if source and destination address
+            // are both null or if they are both instances of Inet6Address.
+            if (matchesIpv6(policy)) {
+                mBpfDscpIpv6Policies.insertOrReplaceEntry(
+                        new Struct.U32(addIndex),
+                        new DscpPolicyValue(policy.getSourceAddress(),
+                                policy.getDestinationAddress(),
+                                policy.getSourcePort(), policy.getDestinationPortRange(),
+                                (short) policy.getProtocol(), (short) policy.getDscpValue()));
+            }
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Failed to insert policy into map: ", e);
+            return STATUS_INSUFFICIENT_PROCESSING_RESOURCES;
+        }
+
+        return STATUS_SUCCESS;
+    }
+
+    /**
+     * Add the provided DSCP policy to the bpf map. Attach bpf program dscp_policy to iface
+     * if not already attached. Response will be sent back to nai with status.
+     *
+     * STATUS_SUCCESS - if policy was added successfully
+     * STATUS_INSUFFICIENT_PROCESSING_RESOURCES - if max policies were already set
+     */
+    public void addDscpPolicy(NetworkAgentInfo nai, DscpPolicy policy) {
+        if (!mAttachedIfaces.contains(nai.linkProperties.getInterfaceName())) {
+            if (!attachProgram(nai.linkProperties.getInterfaceName())) {
+                Log.e(TAG, "Unable to attach program");
+                sendStatus(nai, policy.getPolicyId(), STATUS_INSUFFICIENT_PROCESSING_RESOURCES);
+                return;
+            }
+        }
+
+        int status = addDscpPolicyInternal(policy);
+        sendStatus(nai, policy.getPolicyId(), status);
+    }
+
+    private void removePolicyFromMap(NetworkAgentInfo nai, int policyId, int index) {
+        int status = STATUS_POLICY_NOT_FOUND;
+        try {
+            mBpfDscpIpv4Policies.replaceEntry(new Struct.U32(index), DscpPolicyValue.NONE);
+            mBpfDscpIpv6Policies.replaceEntry(new Struct.U32(index), DscpPolicyValue.NONE);
+            status = STATUS_DELETED;
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Failed to delete policy from map: ", e);
+        }
+
+        sendStatus(nai, policyId, status);
+    }
+
+    /**
+     * Remove specified DSCP policy and detach program if no other policies are active.
+     */
+    public void removeDscpPolicy(NetworkAgentInfo nai, int policyId) {
+        if (!mAttachedIfaces.contains(nai.linkProperties.getInterfaceName())) {
+            // Nothing to remove since program is not attached. Send update back for policy id.
+            sendStatus(nai, policyId, STATUS_POLICY_NOT_FOUND);
+            return;
+        }
+
+        if (mPolicyIdToBpfMapIndex.get(policyId, -1) != -1) {
+            removePolicyFromMap(nai, policyId, mPolicyIdToBpfMapIndex.get(policyId));
+            mPolicyIdToBpfMapIndex.delete(policyId);
+        }
+
+        // TODO: detach should only occur if no more policies are present on the nai's iface.
+        if (mPolicyIdToBpfMapIndex.size() == 0) {
+            detachProgram(nai.linkProperties.getInterfaceName());
+        }
+    }
+
+    /**
+     * Remove all DSCP policies and detach program.
+     */
+    // TODO: Remove all should only remove policies from corresponding nai iface.
+    public void removeAllDscpPolicies(NetworkAgentInfo nai) {
+        if (!mAttachedIfaces.contains(nai.linkProperties.getInterfaceName())) {
+            // Nothing to remove since program is not attached. Send update for policy
+            // id 0. The status update must contain a policy ID, and 0 is an invalid id.
+            sendStatus(nai, 0, STATUS_SUCCESS);
+            return;
+        }
+
+        for (int i = 0; i < mPolicyIdToBpfMapIndex.size(); i++) {
+            removePolicyFromMap(nai, mPolicyIdToBpfMapIndex.keyAt(i),
+                    mPolicyIdToBpfMapIndex.valueAt(i));
+        }
+        mPolicyIdToBpfMapIndex.clear();
+
+        // Can detach program since no policies are active.
+        detachProgram(nai.linkProperties.getInterfaceName());
+    }
+
+    /**
+     * Attach BPF program
+     */
+    private boolean attachProgram(@NonNull String iface) {
+        // TODO: attach needs to be per iface not program.
+
+        try {
+            NetworkInterface netIface = NetworkInterface.getByName(iface);
+            TcUtils.tcFilterAddDevBpf(netIface.getIndex(), false, PRIO_DSCP, (short) ETH_P_ALL,
+                    PROG_PATH);
+        } catch (IOException e) {
+            Log.e(TAG, "Unable to attach to TC on " + iface + ": " + e);
+            return false;
+        }
+        mAttachedIfaces.add(iface);
+        return true;
+    }
+
+    /**
+     * Detach BPF program
+     */
+    public void detachProgram(@NonNull String iface) {
+        try {
+            NetworkInterface netIface = NetworkInterface.getByName(iface);
+            if (netIface != null) {
+                TcUtils.tcFilterDelDev(netIface.getIndex(), false, PRIO_DSCP, (short) ETH_P_ALL);
+            }
+        } catch (IOException e) {
+            Log.e(TAG, "Unable to detach to TC on " + iface + ": " + e);
+        }
+        mAttachedIfaces.remove(iface);
+    }
+}
diff --git a/service/src/com/android/server/connectivity/DscpPolicyValue.java b/service/src/com/android/server/connectivity/DscpPolicyValue.java
new file mode 100644
index 0000000..cb40306
--- /dev/null
+++ b/service/src/com/android/server/connectivity/DscpPolicyValue.java
@@ -0,0 +1,180 @@
+/*
+ * 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 com.android.server.connectivity;
+
+import android.util.Log;
+import android.util.Range;
+
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.Struct.Field;
+import com.android.net.module.util.Struct.Type;
+
+import java.net.Inet4Address;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+/** Value type for DSCP setting and rewriting to DSCP policy BPF maps. */
+public class DscpPolicyValue extends Struct {
+    private static final String TAG = DscpPolicyValue.class.getSimpleName();
+
+    // TODO: add the interface index.
+    @Field(order = 0, type = Type.ByteArray, arraysize = 16)
+    public final byte[] src46;
+
+    @Field(order = 1, type = Type.ByteArray, arraysize = 16)
+    public final byte[] dst46;
+
+    @Field(order = 2, type = Type.UBE16)
+    public final int srcPort;
+
+    @Field(order = 3, type = Type.UBE16)
+    public final int dstPortStart;
+
+    @Field(order = 4, type = Type.UBE16)
+    public final int dstPortEnd;
+
+    @Field(order = 5, type = Type.U8)
+    public final short proto;
+
+    @Field(order = 6, type = Type.U8)
+    public final short dscp;
+
+    @Field(order = 7, type = Type.U8, padding = 3)
+    public final short mask;
+
+    private static final int SRC_IP_MASK = 0x1;
+    private static final int DST_IP_MASK = 0x02;
+    private static final int SRC_PORT_MASK = 0x4;
+    private static final int DST_PORT_MASK = 0x8;
+    private static final int PROTO_MASK = 0x10;
+
+    private boolean ipEmpty(final byte[] ip) {
+        for (int i = 0; i < ip.length; i++) {
+            if (ip[i] != 0) return false;
+        }
+        return true;
+    }
+
+    private byte[] toIpv4MappedAddressBytes(InetAddress ia) {
+        final byte[] addr6 = new byte[16];
+        if (ia != null) {
+            final byte[] addr4 = ia.getAddress();
+            addr6[10] = (byte) 0xff;
+            addr6[11] = (byte) 0xff;
+            addr6[12] = addr4[0];
+            addr6[13] = addr4[1];
+            addr6[14] = addr4[2];
+            addr6[15] = addr4[3];
+        }
+        return addr6;
+    }
+
+    private byte[] toAddressField(InetAddress addr) {
+        if (addr == null) {
+            return EMPTY_ADDRESS_FIELD;
+        } else if (addr instanceof Inet4Address) {
+            return toIpv4MappedAddressBytes(addr);
+        } else {
+            return addr.getAddress();
+        }
+    }
+
+    private static final byte[] EMPTY_ADDRESS_FIELD =
+            InetAddress.parseNumericAddress("::").getAddress();
+
+    private short makeMask(final byte[] src46, final byte[] dst46, final int srcPort,
+            final int dstPortStart, final short proto, final short dscp) {
+        short mask = 0;
+        if (src46 != EMPTY_ADDRESS_FIELD) {
+            mask |= SRC_IP_MASK;
+        }
+        if (dst46 != EMPTY_ADDRESS_FIELD) {
+            mask |=  DST_IP_MASK;
+        }
+        if (srcPort != -1) {
+            mask |=  SRC_PORT_MASK;
+        }
+        if (dstPortStart != -1 && dstPortEnd != -1) {
+            mask |=  DST_PORT_MASK;
+        }
+        if (proto != -1) {
+            mask |=  PROTO_MASK;
+        }
+        return mask;
+    }
+
+    // This constructor is necessary for BpfMap#getValue since all values must be
+    // in the constructor.
+    public DscpPolicyValue(final InetAddress src46, final InetAddress dst46, final int srcPort,
+            final int dstPortStart, final int dstPortEnd, final short proto,
+            final short dscp) {
+        this.src46 = toAddressField(src46);
+        this.dst46 = toAddressField(dst46);
+
+        // These params need to be stored as 0 because uints are used in BpfMap.
+        // If they are -1 BpfMap write will throw errors.
+        this.srcPort = srcPort != -1 ? srcPort : 0;
+        this.dstPortStart = dstPortStart != -1 ? dstPortStart : 0;
+        this.dstPortEnd = dstPortEnd != -1 ? dstPortEnd : 0;
+        this.proto = proto != -1 ? proto : 0;
+
+        this.dscp = dscp;
+        // Use member variables for IP since byte[] is needed and api variables for everything else
+        // so -1 is passed into mask if parameter is not present.
+        this.mask = makeMask(this.src46, this.dst46, srcPort, dstPortStart, proto, dscp);
+    }
+
+    public DscpPolicyValue(final InetAddress src46, final InetAddress dst46, final int srcPort,
+            final Range<Integer> dstPort, final short proto,
+            final short dscp) {
+        this(src46, dst46, srcPort, dstPort != null ? dstPort.getLower() : -1,
+                dstPort != null ? dstPort.getUpper() : -1, proto, dscp);
+    }
+
+    public static final DscpPolicyValue NONE = new DscpPolicyValue(
+            null /* src46 */, null /* dst46 */, -1 /* srcPort */,
+            -1 /* dstPortStart */, -1 /* dstPortEnd */, (short) -1 /* proto */,
+            (short) 0 /* dscp */);
+
+    @Override
+    public String toString() {
+        String srcIpString = "empty";
+        String dstIpString = "empty";
+
+        // Separate try/catch for IP's so it's easier to debug.
+        try {
+            srcIpString = InetAddress.getByAddress(src46).getHostAddress();
+        }  catch (UnknownHostException e) {
+            Log.e(TAG, "Invalid SRC IP address", e);
+        }
+
+        try {
+            dstIpString = InetAddress.getByAddress(src46).getHostAddress();
+        }  catch (UnknownHostException e) {
+            Log.e(TAG, "Invalid DST IP address", e);
+        }
+
+        try {
+            return String.format(
+                    "src46: %s, dst46: %s, srcPort: %d, dstPortStart: %d, dstPortEnd: %d,"
+                    + " protocol: %d, dscp %s", srcIpString, dstIpString, srcPort, dstPortStart,
+                    dstPortEnd, proto, dscp);
+        } catch (IllegalArgumentException e) {
+            return String.format("String format error: " + e);
+        }
+    }
+}
diff --git a/service/src/com/android/server/connectivity/NetworkAgentInfo.java b/service/src/com/android/server/connectivity/NetworkAgentInfo.java
index b7f3ed9..1a7248a 100644
--- a/service/src/com/android/server/connectivity/NetworkAgentInfo.java
+++ b/service/src/com/android/server/connectivity/NetworkAgentInfo.java
@@ -24,6 +24,7 @@
 import android.annotation.Nullable;
 import android.content.Context;
 import android.net.CaptivePortalData;
+import android.net.DscpPolicy;
 import android.net.IDnsResolver;
 import android.net.INetd;
 import android.net.INetworkAgent;
@@ -700,6 +701,24 @@
             mHandler.obtainMessage(NetworkAgent.EVENT_LINGER_DURATION_CHANGED,
                     new Pair<>(NetworkAgentInfo.this, durationMs)).sendToTarget();
         }
+
+        @Override
+        public void sendAddDscpPolicy(final DscpPolicy policy) {
+            mHandler.obtainMessage(NetworkAgent.EVENT_ADD_DSCP_POLICY,
+                    new Pair<>(NetworkAgentInfo.this, policy)).sendToTarget();
+        }
+
+        @Override
+        public void sendRemoveDscpPolicy(final int policyId) {
+            mHandler.obtainMessage(NetworkAgent.EVENT_REMOVE_DSCP_POLICY,
+                    new Pair<>(NetworkAgentInfo.this, policyId)).sendToTarget();
+        }
+
+        @Override
+        public void sendRemoveAllDscpPolicies() {
+            mHandler.obtainMessage(NetworkAgent.EVENT_REMOVE_ALL_DSCP_POLICIES,
+                    new Pair<>(NetworkAgentInfo.this, null)).sendToTarget();
+        }
     }
 
     /**