[RFC bpf-next v7 3/6] selftests/bpf: Add mptcpify program

[Geliang Tang]

This patch implements a new test program mptcpify: if the family is
AF_INET or AF_INET6, the type is SOCK_STREAM, and the protocol ID is
0 or IPPROTO_TCP, set it to IPPROTO_MPTCP.

It will be hooked in update_socket_protocol().

Signed-off-by: Geliang Tang <geliang.tang at suse.com>
---
 tools/testing/selftests/bpf/progs/mptcpify.c | 25 ++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/mptcpify.c

diff --git a/tools/testing/selftests/bpf/progs/mptcpify.c b/tools/testing/selftests/bpf/progs/mptcpify.c
new file mode 100644
index 000000000000..9cf1febe982d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/mptcpify.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023, SUSE. */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+#define	AF_INET		2
+#define	AF_INET6	10
+#define	SOCK_STREAM	1
+#define	IPPROTO_TCP	6
+#define	IPPROTO_MPTCP	262
+
+SEC("fmod_ret/update_socket_protocol")
+int BPF_PROG(mptcpify, int family, int type, int protocol)
+{
+	if ((family == AF_INET || family == AF_INET6) &&
+	    type == SOCK_STREAM &&
+	    (!protocol || protocol == IPPROTO_TCP)) {
+		return IPPROTO_MPTCP;
+	}
+
+	return protocol;
+}
-- 
2.35.3