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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 A9744C4338F for ; Mon, 16 Aug 2021 20:51:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A5E160E76 for ; Mon, 16 Aug 2021 20:51:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233194AbhHPUwX (ORCPT ); Mon, 16 Aug 2021 16:52:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231783AbhHPUwW (ORCPT ); Mon, 16 Aug 2021 16:52:22 -0400 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F072CC061764 for ; Mon, 16 Aug 2021 13:51:50 -0700 (PDT) Received: by mail-pj1-x1033.google.com with SMTP id bo18so28571745pjb.0 for ; Mon, 16 Aug 2021 13:51:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=QNjLAMi+CxbQNlMbdfMf25HypiSkR+DmhakI6VpxXA0=; b=s7qhenr+bDstqR1GKR+J66HFpXEjg0p/97bIbOkWy9TiVs8Swa9rTHUYH5XbcfMWGB N4JytoFqPSFTaFMiF2SouGgxKFnh8+J2mHntp7WrnSpULymUxwMG80f7+oS+LkutABYQ TThLdLY3bB60UTvmt6bC0HIGnDKn6LNKWFM4ujw1BvPa+cKHMTxKn2y3ArfX12ka+g60 tgA/ztqJuREsv+RaAJ1LiODH10sm6EYE6ARECH+xLQ2zxqghjwTbefyCXSiu1CtF9LD/ 0mu8YZuOslFnqpk0mgYx6wbyKk99okGl/Qm37ZwQ8AmbH3nk3uLyCUxVfv9Sw6fkCbX2 XYIw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=QNjLAMi+CxbQNlMbdfMf25HypiSkR+DmhakI6VpxXA0=; b=C+6k8BQDl2UV3N8ts33X/W3mpD50g4luwgJfdoRm1k6zEfH3VKUb9uYkrzufkeM581 71a4RcWsqv5p/HquqzDGQp1OgVQQtnyp5d0hzOLMCQKRi7rKRESImNmns4JL0z6vU8tg LKt5v/r3uJgV5ZOxXVo6OId95pRKBRWWtB1Kw61WQu+wBqPPjfBMqiJAars5VXaoQfB3 RtqVrVhXnUXvJR9Y1iPLkhJJMqLa9jtwfeIUuttjp6JwKNexRDZiYuJy+kMa8jkexTMO YZXRtz4LlV2mGuYgZu7XB6q3lDDLqnweisY4/b9m6zcOZ2nqyheI/qRCAjAhQC+BK40R HNGg== X-Gm-Message-State: AOAM530JewHkiZ7XhgjDHysinEtKqzcNZ8JsyuaFvdMgIsuvV/7HZ4Al 3oKkIKWAefXFZXOgRsUHtDxvM9sgoJaBGA== X-Google-Smtp-Source: ABdhPJwFKavWiZ3Dezs+ZOs3vQX53fXnpVkQ+ckap/TcYSIFVSMwhXM3ayD5hsMMV4I+uej00H+O2A== X-Received: by 2002:a17:902:9a02:b029:118:307e:a9dd with SMTP id v2-20020a1709029a02b0290118307ea9ddmr51053plp.47.1629147110301; Mon, 16 Aug 2021 13:51:50 -0700 (PDT) Received: from lukehsiao.c.googlers.com.com (190.40.105.34.bc.googleusercontent.com. [34.105.40.190]) by smtp.gmail.com with ESMTPSA id t30sm64087pgl.47.2021.08.16.13.51.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Aug 2021 13:51:49 -0700 (PDT) From: Luke Hsiao To: David Miller Cc: netdev@vger.kernel.org, Luke Hsiao , Neal Cardwell , Yuchung Cheng , Eric Dumazet Subject: [PATCH net-next] tcp: enable data-less, empty-cookie SYN with TFO_SERVER_COOKIE_NOT_REQD Date: Mon, 16 Aug 2021 20:51:06 +0000 Message-Id: <20210816205105.2533289-1-luke.w.hsiao@gmail.com> X-Mailer: git-send-email 2.33.0.rc1.237.g0d66db33f3-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Luke Hsiao Since the original TFO server code was implemented in commit 168a8f58059a22feb9e9a2dcc1b8053dbbbc12ef ("tcp: TCP Fast Open Server - main code path") the TFO server code has supported the sysctl bit flag TFO_SERVER_COOKIE_NOT_REQD. Currently, when the TFO_SERVER_ENABLE and TFO_SERVER_COOKIE_NOT_REQD sysctl bit flags are set, a server connection will accept a SYN with N bytes of data (N > 0) that has no TFO cookie, create a new fast open connection, process the incoming data in the SYN, and make the connection ready for accepting. After accepting, the connection is ready for read()/recvmsg() to read the N bytes of data in the SYN, ready for write()/sendmsg() calls and data transmissions to transmit data. This commit changes an edge case in this feature by changing this behavior to apply to (N >= 0) bytes of data in the SYN rather than only (N > 0) bytes of data in the SYN. Now, a server will accept a data-less SYN without a TFO cookie if TFO_SERVER_COOKIE_NOT_REQD is set. Caveat! While this enables a new kind of TFO (data-less empty-cookie SYN), some firewall rules setup may not work if they assume such packets are not legit TFOs and will filter them. Signed-off-by: Luke Hsiao Acked-by: Neal Cardwell Acked-by: Yuchung Cheng Signed-off-by: Eric Dumazet --- net/ipv4/tcp_fastopen.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c index 62ba8d0f2c60..59412d6354a0 100644 --- a/net/ipv4/tcp_fastopen.c +++ b/net/ipv4/tcp_fastopen.c @@ -368,8 +368,7 @@ struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, return NULL; } - if (syn_data && - tcp_fastopen_no_cookie(sk, dst, TFO_SERVER_COOKIE_NOT_REQD)) + if (tcp_fastopen_no_cookie(sk, dst, TFO_SERVER_COOKIE_NOT_REQD)) goto fastopen; if (foc->len == 0) { -- 2.33.0.rc1.237.g0d66db33f3-goog