From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78112C32772 for ; Tue, 23 Aug 2022 11:23:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236827AbiHWLXB (ORCPT ); Tue, 23 Aug 2022 07:23:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37498 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244023AbiHWLRj (ORCPT ); Tue, 23 Aug 2022 07:17:39 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2665689820; Tue, 23 Aug 2022 02:21:18 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id BB6C1B81C65; Tue, 23 Aug 2022 09:21:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE683C433C1; Tue, 23 Aug 2022 09:21:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661246476; bh=NeHKc98R14zR8ENVc6BjZmsKaav6RKSz1RkV7bt+kvw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F7xeaFzpwMmWzbZ3xVDtZ/wvZ8VnadjaRCMVidxCDQmq102/90AlKoek+uvhbTS3+ Fhmzdakof7QdPMRORflGHwGH3r3uTFUrXe/p07Bp6eDPFDHNZKQ68JEVvnEy2DcgUz SVKUmyKEkvJqc0Se6bWluQz/FkDxlsrJcUXEB3so= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yonglong Li , Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.4 122/389] tcp: make retransmitted SKB fit into the send window Date: Tue, 23 Aug 2022 10:23:20 +0200 Message-Id: <20220823080120.701174987@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080115.331990024@linuxfoundation.org> References: <20220823080115.331990024@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yonglong Li [ Upstream commit 536a6c8e05f95e3d1118c40ae8b3022ee2d05d52 ] current code of __tcp_retransmit_skb only check TCP_SKB_CB(skb)->seq in send window, and TCP_SKB_CB(skb)->seq_end maybe out of send window. If receiver has shrunk his window, and skb is out of new window, it should retransmit a smaller portion of the payload. test packetdrill script: 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 fcntl(3, F_GETFL) = 0x2 (flags O_RDWR) +0 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 +0 connect(3, ..., ...) = -1 EINPROGRESS (Operation now in progress) +0 > S 0:0(0) win 65535 +.05 < S. 0:0(0) ack 1 win 6000 +0 > . 1:1(0) ack 1 +0 write(3, ..., 10000) = 10000 +0 > . 1:2001(2000) ack 1 win 65535 +0 > . 2001:4001(2000) ack 1 win 65535 +0 > . 4001:6001(2000) ack 1 win 65535 +.05 < . 1:1(0) ack 4001 win 1001 and tcpdump show: 192.168.226.67.55 > 192.0.2.1.8080: Flags [.], seq 1:2001, ack 1, win 65535, length 2000 192.168.226.67.55 > 192.0.2.1.8080: Flags [.], seq 2001:4001, ack 1, win 65535, length 2000 192.168.226.67.55 > 192.0.2.1.8080: Flags [P.], seq 4001:5001, ack 1, win 65535, length 1000 192.168.226.67.55 > 192.0.2.1.8080: Flags [.], seq 5001:6001, ack 1, win 65535, length 1000 192.0.2.1.8080 > 192.168.226.67.55: Flags [.], ack 4001, win 1001, length 0 192.168.226.67.55 > 192.0.2.1.8080: Flags [.], seq 5001:6001, ack 1, win 65535, length 1000 192.168.226.67.55 > 192.0.2.1.8080: Flags [P.], seq 4001:5001, ack 1, win 65535, length 1000 when cient retract window to 1001, send window is [4001,5002], but TLP send 5001-6001 packet which is out of send window. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Yonglong Li Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/1657532838-20200-1-git-send-email-liyonglong@chinatelecom.cn Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/tcp_output.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index ef749a47768a..fa7fb30e4b59 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2911,7 +2911,7 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) struct tcp_sock *tp = tcp_sk(sk); unsigned int cur_mss; int diff, len, err; - + int avail_wnd; /* Inconclusive MTU probe */ if (icsk->icsk_mtup.probe_size) @@ -2941,17 +2941,25 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) return -EHOSTUNREACH; /* Routing failure or similar. */ cur_mss = tcp_current_mss(sk); + avail_wnd = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; /* If receiver has shrunk his window, and skb is out of * new window, do not retransmit it. The exception is the * case, when window is shrunk to zero. In this case - * our retransmit serves as a zero window probe. + * our retransmit of one segment serves as a zero window probe. */ - if (!before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp)) && - TCP_SKB_CB(skb)->seq != tp->snd_una) - return -EAGAIN; + if (avail_wnd <= 0) { + if (TCP_SKB_CB(skb)->seq != tp->snd_una) + return -EAGAIN; + avail_wnd = cur_mss; + } len = cur_mss * segs; + if (len > avail_wnd) { + len = rounddown(avail_wnd, cur_mss); + if (!len) + len = avail_wnd; + } if (skb->len > len) { if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len, cur_mss, GFP_ATOMIC)) @@ -2965,8 +2973,9 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) diff -= tcp_skb_pcount(skb); if (diff) tcp_adjust_pcount(sk, skb, diff); - if (skb->len < cur_mss) - tcp_retrans_try_collapse(sk, skb, cur_mss); + avail_wnd = min_t(int, avail_wnd, cur_mss); + if (skb->len < avail_wnd) + tcp_retrans_try_collapse(sk, skb, avail_wnd); } /* RFC3168, section 6.1.1.1. ECN fallback */ -- 2.35.1