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Commit 1e215300 authored by Nikita V. Shirokov's avatar Nikita V. Shirokov Committed by Daniel Borkmann
Browse files

bpf: add TCP_SAVE_SYN/TCP_SAVED_SYN options for bpf_(set|get)sockopt 



Adding support for two new bpf get/set sockopts: TCP_SAVE_SYN (set)
and TCP_SAVED_SYN (get). This would allow for bpf program to build
logic based on data from ingress SYN packet (e.g. doing tcp's tos/
tclass reflection (see sample prog)) and do it transparently from
userspace program point of view.

Signed-off-by: default avatarNikita V. Shirokov <tehnerd@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 72962167

net/core/filter.c

+21 −4
Original line number Diff line number Diff line
@@ -4007,6 +4007,12 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock, 
					tp->snd_ssthresh = val;

				}

				break;

			case TCP_SAVE_SYN:

				if (val < 0 || val > 1)

					ret = -EINVAL;

				else

					tp->save_syn = val;

				break;

			default:

				ret = -EINVAL;

			}
@@ -4032,21 +4038,32 @@ static const struct bpf_func_proto bpf_setsockopt_proto = { 
BPF_CALL_5(bpf_getsockopt, struct bpf_sock_ops_kern *, bpf_sock,

	   int, level, int, optname, char *, optval, int, optlen)

{

	struct inet_connection_sock *icsk;

	struct sock *sk = bpf_sock->sk;

	struct tcp_sock *tp;



	if (!sk_fullsock(sk))

		goto err_clear;



#ifdef CONFIG_INET

	if (level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) {

		if (optname == TCP_CONGESTION) {

			struct inet_connection_sock *icsk = inet_csk(sk);

		switch (optname) {

		case TCP_CONGESTION:

			icsk = inet_csk(sk);



			if (!icsk->icsk_ca_ops || optlen <= 1)

				goto err_clear;

			strncpy(optval, icsk->icsk_ca_ops->name, optlen);

			optval[optlen - 1] = 0;

		} else {

			break;

		case TCP_SAVED_SYN:

			tp = tcp_sk(sk);



			if (optlen <= 0 || !tp->saved_syn ||

			    optlen > tp->saved_syn[0])

				goto err_clear;

			memcpy(optval, tp->saved_syn + 1, optlen);

			break;

		default:

			goto err_clear;

		}

	} else if (level == SOL_IP) {