Commit cb811109 authored by Prankur gupta's avatar Prankur gupta Committed by Alexei Starovoitov
Browse files

bpf: Adds support for setting window clamp 



Adds a new bpf_setsockopt for TCP sockets, TCP_BPF_WINDOW_CLAMP,
which sets the maximum receiver window size. It will be useful for
limiting receiver window based on RTT.

Signed-off-by: default avatarPrankur gupta <prankgup@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201202213152.435886-2-prankgup@fb.com
parent 2faa7328

include/net/tcp.h

+1 −0
Original line number Diff line number Diff line
@@ -406,6 +406,7 @@ void tcp_syn_ack_timeout(const struct request_sock *req); 
int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,

		int flags, int *addr_len);

int tcp_set_rcvlowat(struct sock *sk, int val);

int tcp_set_window_clamp(struct sock *sk, int val);

void tcp_data_ready(struct sock *sk);

#ifdef CONFIG_MMU

int tcp_mmap(struct file *file, struct socket *sock,

net/core/filter.c

+3 −0
Original line number Diff line number Diff line
@@ -4910,6 +4910,9 @@ static int _bpf_setsockopt(struct sock *sk, int level, int optname, 
				tp->notsent_lowat = val;

				sk->sk_write_space(sk);

				break;

			case TCP_WINDOW_CLAMP:

				ret = tcp_set_window_clamp(sk, val);

				break;

			default:

				ret = -EINVAL;

			}

net/ipv4/tcp.c

+16 −9
Original line number Diff line number Diff line
@@ -3022,6 +3022,21 @@ int tcp_sock_set_keepcnt(struct sock *sk, int val) 
}

EXPORT_SYMBOL(tcp_sock_set_keepcnt);



int tcp_set_window_clamp(struct sock *sk, int val)

{

	struct tcp_sock *tp = tcp_sk(sk);



	if (!val) {

		if (sk->sk_state != TCP_CLOSE)

			return -EINVAL;

		tp->window_clamp = 0;

	} else {

		tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?

			SOCK_MIN_RCVBUF / 2 : val;

	}

	return 0;

}



/*

 *	Socket option code for TCP.

 */
@@ -3235,15 +3250,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname, 
		break;



	case TCP_WINDOW_CLAMP:

		if (!val) {

			if (sk->sk_state != TCP_CLOSE) {

				err = -EINVAL;

				break;

			}

			tp->window_clamp = 0;

		} else

			tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ?

						SOCK_MIN_RCVBUF / 2 : val;

		err = tcp_set_window_clamp(sk, val);

		break;



	case TCP_QUICKACK:

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