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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable 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 078DDC433E0 for ; Fri, 12 Jun 2020 10:15:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D6FEB206A4 for ; Fri, 12 Jun 2020 10:15:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="b9KwvlW4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725868AbgFLKPv (ORCPT ); Fri, 12 Jun 2020 06:15:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44964 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726275AbgFLKPh (ORCPT ); Fri, 12 Jun 2020 06:15:37 -0400 Received: from mail-lj1-x242.google.com (mail-lj1-x242.google.com [IPv6:2a00:1450:4864:20::242]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 638D8C08C5C1 for ; Fri, 12 Jun 2020 03:15:36 -0700 (PDT) Received: by mail-lj1-x242.google.com with SMTP id e4so10467663ljn.4 for ; Fri, 12 Jun 2020 03:15:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=/gbHlr0KqPDkStZANGWcajnn6OdrqVI8OcC2DaXaFRY=; b=b9KwvlW4LejDyrkRYv5SvjtOE6OMNofyEWm9A7xUh1tcYnGbI0lRXrPHJQSjFa/zXC 06OdNtxbEmQS6HkUgkxADSsmxgI0buOOKVSZb6+n8z43YEcJ6nBbnhyRCkAokVq7ha/i Afjz5FYNc1SGY1zJXPJhIs5GxkJQtz774QDLk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=/gbHlr0KqPDkStZANGWcajnn6OdrqVI8OcC2DaXaFRY=; b=pomgGYodSBAPD927SB6bersEDQywRqngj36k+FFOZb1hLOG65r7TVwj0fQSfA5uXNu Sy4rHxhjDy9a0TOH+JtQrAXu2Bey/+b4ZfnfHWUjdOOvxjLfSvnhSxQWJbEvnq7Huta9 z876xcSjZaWfIGKxq+n7KAieiqCbYm363Ft6ESq2yVmVf7Eu+v8usQ9gkNPJQd8U6LP9 Ef6+J78W7mXSWJd/wioqHIPvQOhA/ujWVyF2e3ticfPknvDp4H/QbguPL545iDfxzZ9z YR0j1MEG+KOERatsbkSp+uE4hQFCKktywIG8YnLLnA4avlWYa8edUkl87LQ9S4o7mhwQ ouRw== X-Gm-Message-State: AOAM533Hh0Qb3yqg7+f2Q5/jyYp4EyPQ3XgbW4m43jLbGI6P1s048Tsz DkJzFhJHSUQ4TeVO0VNQmg5nRQ== X-Google-Smtp-Source: ABdhPJwBFZTgyd1+YZ2YR2Zp9TGIIZadEUbsi3pQARgJGt4sMdi7U4PqKKM6y5drMqNORdkgBwb4cA== X-Received: by 2002:a2e:5c2:: with SMTP id 185mr6083410ljf.260.1591956934738; Fri, 12 Jun 2020 03:15:34 -0700 (PDT) Received: from toad ([2a02:a310:c262:aa00:b35e:8938:2c2a:ba8b]) by smtp.gmail.com with ESMTPSA id t7sm1659609lfq.64.2020.06.12.03.15.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jun 2020 03:15:34 -0700 (PDT) Date: Fri, 12 Jun 2020 12:15:26 +0200 From: Jakub Sitnicki To: Sabrina Dubroca Cc: netdev@vger.kernel.org, John Fastabend , Daniel Borkmann , bpf@vger.kernel.org Subject: Re: [PATCH bpf] bpf: tcp: recv() should return 0 when the peer socket is closed Message-ID: <20200612121526.4810a073@toad> In-Reply-To: <26038a28c21fea5d04d4bd4744c5686d3f2e5504.1591784177.git.sd@queasysnail.net> References: <26038a28c21fea5d04d4bd4744c5686d3f2e5504.1591784177.git.sd@queasysnail.net> X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, 10 Jun 2020 12:19:43 +0200 Sabrina Dubroca wrote: > If the peer is closed, we will never get more data, so > tcp_bpf_wait_data will get stuck forever. In case we passed > MSG_DONTWAIT to recv(), we get EAGAIN but we should actually get > 0. > > From man 2 recv: > > RETURN VALUE > > When a stream socket peer has performed an orderly shutdown, the > return value will be 0 (the traditional "end-of-file" return). > > This patch makes tcp_bpf_wait_data always return 1 when the peer > socket has been shutdown. Either we have data available, and it would > have returned 1 anyway, or there isn't, in which case we'll call > tcp_recvmsg which does the right thing in this situation. > > Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") > Signed-off-by: Sabrina Dubroca > --- > net/ipv4/tcp_bpf.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c > index 2b915aafda42..7aa68f4aae6c 100644 > --- a/net/ipv4/tcp_bpf.c > +++ b/net/ipv4/tcp_bpf.c > @@ -245,6 +245,9 @@ static int tcp_bpf_wait_data(struct sock *sk, struct sk_psock *psock, > DEFINE_WAIT_FUNC(wait, woken_wake_function); > int ret = 0; > > + if (sk->sk_shutdown & RCV_SHUTDOWN) > + return 1; > + > if (!timeo) > return ret; > Acked-by: Jakub Sitnicki