1 /*
2  * Copyright (C) 2022 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #pragma once
18 
19 /* -=-=-=-=-= WARNING -=-=-=-=-=-
20  *
21  * DO *NOT* *EVER* CHANGE THIS CONSTANT
22  *
23  * This is aidl::android::net::INetd::CLAT_MARK but we can't use that from
24  * pure C code (ie. the eBPF clat program).
25  *
26  * It must match the iptables rules setup by netd on Android T.
27  *
28  * This mark value is used by the eBPF clatd program to mark ingress non-offloaded clat
29  * packets for later dropping in ip6tables bw_raw_PREROUTING.
30  * They need to be dropped *after* the clat daemon (via receive on an AF_PACKET socket)
31  * sees them and thus cannot be dropped from the bpf program itself.
32  */
33 static const uint32_t CLAT_MARK = 0xDEADC1A7;
34