From patchwork Tue Nov 17 13:05:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 325435 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BFAFC2D0E4 for ; Tue, 17 Nov 2020 13:12:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C8273246BC for ; Tue, 17 Nov 2020 13:12:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="E/YVvBbe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729657AbgKQNLp (ORCPT ); Tue, 17 Nov 2020 08:11:45 -0500 Received: from mail.kernel.org ([198.145.29.99]:41440 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729684AbgKQNLk (ORCPT ); Tue, 17 Nov 2020 08:11:40 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 445922151B; Tue, 17 Nov 2020 13:11:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605618699; bh=m+sQWvrHBDpseuELJ6B+axcZo0qC0fNk2XlDA3S34nY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E/YVvBbe6CCbOstkxI9xmfxzr4ijEmemm2qR/YfgekWOuRLQNeEyfF8n6HuPaLn8f 7USNL7ocZxuK36AjyHa0mXvmAZloDCADfqh7cOj5TSLNfnUhvdfH1wBOqeiysq6fHF tyVDVhNdzcHVezX55+PatljKdO5l/32A/ZGJSF70= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mao Wenan , Eric Dumazet , Jakub Kicinski Subject: [PATCH 4.9 56/78] net: Update window_clamp if SOCK_RCVBUF is set Date: Tue, 17 Nov 2020 14:05:22 +0100 Message-Id: <20201117122111.852475280@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201117122109.116890262@linuxfoundation.org> References: <20201117122109.116890262@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mao Wenan [ Upstream commit 909172a149749242990a6e64cb55d55460d4e417 ] 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 Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/1604967391-123737-1-git-send-email-wenan.mao@linux.alibaba.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/ipv4/syncookies.c | 9 +++++++-- net/ipv6/syncookies.c | 10 ++++++++-- 2 files changed, 15 insertions(+), 4 deletions(-) --- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -304,7 +304,7 @@ struct sock *cookie_v4_check(struct sock __u32 cookie = ntohl(th->ack_seq) - 1; struct sock *ret = sk; struct request_sock *req; - int mss; + int full_space, mss; struct rtable *rt; __u8 rcv_wscale; struct flowi4 fl4; @@ -388,8 +388,13 @@ struct sock *cookie_v4_check(struct sock /* 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 */ + full_space = tcp_full_space(sk); + 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(tcp_full_space(sk), req->mss, + tcp_select_initial_window(full_space, req->mss, &req->rsk_rcv_wnd, &req->rsk_window_clamp, ireq->wscale_ok, &rcv_wscale, dst_metric(&rt->dst, RTAX_INITRWND)); --- a/net/ipv6/syncookies.c +++ b/net/ipv6/syncookies.c @@ -143,7 +143,7 @@ struct sock *cookie_v6_check(struct sock __u32 cookie = ntohl(th->ack_seq) - 1; struct sock *ret = sk; struct request_sock *req; - int mss; + int full_space, mss; struct dst_entry *dst; __u8 rcv_wscale; @@ -236,7 +236,13 @@ struct sock *cookie_v6_check(struct sock } req->rsk_window_clamp = tp->window_clamp ? :dst_metric(dst, RTAX_WINDOW); - tcp_select_initial_window(tcp_full_space(sk), req->mss, + /* limit the window selection if the user enforce a smaller rx buffer */ + full_space = tcp_full_space(sk); + 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(full_space, req->mss, &req->rsk_rcv_wnd, &req->rsk_window_clamp, ireq->wscale_ok, &rcv_wscale, dst_metric(dst, RTAX_INITRWND));