[PATCH net-next v4 05/16] bpf: Support for setting initial receive window
From: Lawrence Brakmo <hidden>
Date: 2017-06-28 17:31:31
Subsystem:
bpf [general] (safe dynamic programs and tools), networking [general], networking [tcp], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
This patch adds suppport for setting the initial advertized window from within a BPF_SOCK_OPS program. This can be used to support larger initial cwnd values in environments where it is known to be safe. Signed-off-by: Lawrence Brakmo <redacted> --- include/net/tcp.h | 10 ++++++++++ include/uapi/linux/bpf.h | 4 ++++ net/ipv4/tcp_minisocks.c | 9 ++++++++- net/ipv4/tcp_output.c | 7 ++++++- 4 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index cd9ef63..af404aa 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h@@ -2069,4 +2069,14 @@ static inline u32 tcp_timeout_init(struct sock *sk, bool is_req_sock) return timeout; } +static inline u32 tcp_rwnd_init_bpf(struct sock *sk, bool is_req_sock) +{ + int rwnd; + + rwnd = tcp_call_bpf(sk, is_req_sock, BPF_SOCK_OPS_RWND_INIT); + + if (rwnd < 0) + rwnd = 0; + return rwnd; +} #endif /* _TCP_H */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4174668..cdec348 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h@@ -749,6 +749,10 @@ enum { BPF_SOCK_OPS_TIMEOUT_INIT, /* Should return SYN-RTO value to use or * -1 if default value should be used */ + BPF_SOCK_OPS_RWND_INIT, /* Should return initial advertized + * window (in packets) or -1 if default + * value should be used + */ }; #endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index d30ee31..bbaf3c6 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c@@ -351,6 +351,7 @@ void tcp_openreq_init_rwin(struct request_sock *req, int full_space = tcp_full_space(sk_listener); u32 window_clamp; __u8 rcv_wscale; + u32 rcv_wnd; int mss; mss = tcp_mss_clamp(tp, dst_metric_advmss(dst));
@@ -363,6 +364,12 @@ void tcp_openreq_init_rwin(struct request_sock *req, (req->rsk_window_clamp > full_space || req->rsk_window_clamp == 0)) req->rsk_window_clamp = full_space; + rcv_wnd = tcp_rwnd_init_bpf((struct sock *)req, true); + if (rcv_wnd == 0) + rcv_wnd = dst_metric(dst, RTAX_INITRWND); + else if (full_space < rcv_wnd * mss) + full_space = rcv_wnd * mss; + /* tcp_full_space because it is guaranteed to be the first packet */ tcp_select_initial_window(full_space, mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0),
@@ -370,7 +377,7 @@ void tcp_openreq_init_rwin(struct request_sock *req, &req->rsk_window_clamp, ireq->wscale_ok, &rcv_wscale, - dst_metric(dst, RTAX_INITRWND)); + rcv_wnd); ireq->rcv_wscale = rcv_wscale; } EXPORT_SYMBOL(tcp_openreq_init_rwin);
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 5e478a1..e5f623f 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c@@ -3267,6 +3267,7 @@ static void tcp_connect_init(struct sock *sk) const struct dst_entry *dst = __sk_dst_get(sk); struct tcp_sock *tp = tcp_sk(sk); __u8 rcv_wscale; + u32 rcv_wnd; /* We'll fix this up when we get a response from the other end. * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT.
@@ -3300,13 +3301,17 @@ static void tcp_connect_init(struct sock *sk) (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) tp->window_clamp = tcp_full_space(sk); + rcv_wnd = tcp_rwnd_init_bpf(sk, false); + if (rcv_wnd == 0) + rcv_wnd = dst_metric(dst, RTAX_INITRWND); + tcp_select_initial_window(tcp_full_space(sk), tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), &tp->rcv_wnd, &tp->window_clamp, sock_net(sk)->ipv4.sysctl_tcp_window_scaling, &rcv_wscale, - dst_metric(dst, RTAX_INITRWND)); + rcv_wnd); tp->rx_opt.rcv_wscale = rcv_wscale; tp->rcv_ssthresh = tp->rcv_wnd;
--
2.9.3