From patchwork Mon Nov 9 16:53:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mao Wenan X-Patchwork-Id: 1396917 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4CVHC608pMz9sRR for ; Tue, 10 Nov 2020 03:54:10 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730863AbgKIQyG (ORCPT ); Mon, 9 Nov 2020 11:54:06 -0500 Received: from out30-54.freemail.mail.aliyun.com ([115.124.30.54]:59444 "EHLO out30-54.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730202AbgKIQyF (ORCPT ); Mon, 9 Nov 2020 11:54:05 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R921e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=wenan.mao@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0UEoLgHG_1604940832; Received: from VM20200710-3.tbsite.net(mailfrom:wenan.mao@linux.alibaba.com fp:SMTPD_---0UEoLgHG_1604940832) by smtp.aliyun-inc.com(127.0.0.1); Tue, 10 Nov 2020 00:54:00 +0800 From: Mao Wenan To: edumazet@google.com, davem@davemloft.net, kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org, kuba@kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Mao Wenan Subject: [PATCH net v3] net: Update window_clamp if SOCK_RCVBUF is set Date: Tue, 10 Nov 2020 00:53:50 +0800 Message-Id: <1604940830-74688-1-git-send-email-wenan.mao@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: References: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When net.ipv4.tcp_syncookies=1 and syn flood is happened, cookie_v4_check or cookie_v6_check tries to redo what tcp_v4_send_synack or tcp_v6_send_synack did, rsk_window_clamp will be changed if SOCK_RCVBUF is set, which will make rcv_wscale is different, the client still operates with initial window scale and can overshot granted window, the client use the initial scale but local server use new scale to advertise window value, and session work abnormally. Fixes: e88c64f0a425 ("tcp: allow effective reduction of TCP's rcv-buffer via setsockopt") Signed-off-by: Mao Wenan --- v3: add local variable full_space, add fixes tag. v2: fix for ipv6. net/ipv4/syncookies.c | 7 ++++++- net/ipv6/syncookies.c | 8 +++++++- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c index 6ac473b..eea4698 100644 --- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -327,6 +327,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb) struct inet_request_sock *ireq; struct tcp_request_sock *treq; struct tcp_sock *tp = tcp_sk(sk); + int full_space = tcp_full_space(sk); const struct tcphdr *th = tcp_hdr(skb); __u32 cookie = ntohl(th->ack_seq) - 1; struct sock *ret = sk; @@ -427,8 +428,12 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb) /* Try to redo what tcp_v4_send_synack did. */ req->rsk_window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW); + /* limit the window selection if the user enforce a smaller rx buffer */ + if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && + (req->rsk_window_clamp > full_space || req->rsk_window_clamp == 0)) + req->rsk_window_clamp = full_space; - tcp_select_initial_window(sk, tcp_full_space(sk), req->mss, + tcp_select_initial_window(sk, full_space, req->mss, &req->rsk_rcv_wnd, &req->rsk_window_clamp, ireq->wscale_ok, &rcv_wscale, dst_metric(&rt->dst, RTAX_INITRWND)); diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c index e796a64..5b09bb6 100644 --- a/net/ipv6/syncookies.c +++ b/net/ipv6/syncookies.c @@ -132,6 +132,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb) struct tcp_request_sock *treq; struct ipv6_pinfo *np = inet6_sk(sk); struct tcp_sock *tp = tcp_sk(sk); + int full_space = tcp_full_space(sk); const struct tcphdr *th = tcp_hdr(skb); __u32 cookie = ntohl(th->ack_seq) - 1; struct sock *ret = sk; @@ -241,7 +242,12 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb) } req->rsk_window_clamp = tp->window_clamp ? :dst_metric(dst, RTAX_WINDOW); - tcp_select_initial_window(sk, tcp_full_space(sk), req->mss, + /* limit the window selection if the user enforce a smaller rx buffer */ + if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && + (req->rsk_window_clamp > full_space || req->rsk_window_clamp == 0)) + req->rsk_window_clamp = full_space; + + tcp_select_initial_window(sk, full_space, req->mss, &req->rsk_rcv_wnd, &req->rsk_window_clamp, ireq->wscale_ok, &rcv_wscale, dst_metric(dst, RTAX_INITRWND));