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bpf: Adds support for setting window clamp

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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: Prankur gupta <prankgup@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201202213152.435886-2-prankgup@fb.com
This commit is contained in:
Prankur gupta 2020-12-02 13:31:51 -08:00 committed by Alexei Starovoitov
parent 2faa7328f5
commit cb81110997
3 changed files with 20 additions and 9 deletions
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1
include/net/tcp.h
View File

@ -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,

3
net/core/filter.c
View File

@ -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;
}

25
net/ipv4/tcp.c
View File

@ -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: