1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/stddef.h>
4 #include <linux/bpf.h>
5 #include <sys/types.h>
6 #include <sys/socket.h>
7 #include <bpf/bpf_helpers.h>
8 #include <bpf/bpf_endian.h>
9 
10 static __always_inline int bind_prog(struct bpf_sock_addr *ctx, int family)
11 {
12 	struct bpf_sock *sk;
13 
14 	sk = ctx->sk;
15 	if (!sk)
16 		return 0;
17 
18 	if (sk->family != family)
19 		return 0;
20 
21 	if (ctx->type != SOCK_STREAM)
22 		return 0;
23 
24 	/* Return 1 OR'ed with the first bit set to indicate
25 	 * that CAP_NET_BIND_SERVICE should be bypassed.
26 	 */
27 	if (ctx->user_port == bpf_htons(111))
28 		return (1 | 2);
29 
30 	return 1;
31 }
32 
33 SEC("cgroup/bind4")
34 int bind_v4_prog(struct bpf_sock_addr *ctx)
35 {
36 	return bind_prog(ctx, AF_INET);
37 }
38 
39 SEC("cgroup/bind6")
40 int bind_v6_prog(struct bpf_sock_addr *ctx)
41 {
42 	return bind_prog(ctx, AF_INET6);
43 }
44 
45 char _license[] SEC("license") = "GPL";
46