1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2023, SUSE. */
 3
 4#include "vmlinux.h"
 5#include <bpf/bpf_tracing.h>
 6#include "bpf_tracing_net.h"
 7
 8char _license[] SEC("license") = "GPL";
 9int pid;
10
11SEC("fmod_ret/update_socket_protocol")
12int BPF_PROG(mptcpify, int family, int type, int protocol)
13{
14	if (bpf_get_current_pid_tgid() >> 32 != pid)
15		return protocol;
16
17	if ((family == AF_INET || family == AF_INET6) &&
18	    type == SOCK_STREAM &&
19	    (!protocol || protocol == IPPROTO_TCP)) {
20		return IPPROTO_MPTCP;
21	}
22
23	return protocol;
24}