From cb81110997d1f5097f29dd8e49d32a1fc55cbf86 Mon Sep 17 00:00:00 2001 From: Prankur gupta Date: Wed, 2 Dec 2020 13:31:51 -0800 Subject: [PATCH] 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: Prankur gupta Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201202213152.435886-2-prankgup@fb.com --- include/net/tcp.h | 1 + net/core/filter.c | 3 +++ net/ipv4/tcp.c | 25 ++++++++++++++++--------- 3 files changed, 20 insertions(+), 9 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 4aba0f069b05..347a76f176b4 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -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, diff --git a/net/core/filter.c b/net/core/filter.c index 21d91dcf0260..77001a35768f 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -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; } diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index b2bc3d7fe9e8..17379f6dd955 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -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: -- 2.11.0