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 C3A16C77B61 for ; Fri, 7 Apr 2023 17:17:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230136AbjDGRRP (ORCPT ); Fri, 7 Apr 2023 13:17:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230089AbjDGRRF (ORCPT ); Fri, 7 Apr 2023 13:17:05 -0400 Received: from mail-pj1-x102f.google.com (mail-pj1-x102f.google.com [IPv6:2607:f8b0:4864:20::102f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5DE63AD13; Fri, 7 Apr 2023 10:17:04 -0700 (PDT) Received: by mail-pj1-x102f.google.com with SMTP id j14-20020a17090a7e8e00b002448c0a8813so4058839pjl.0; Fri, 07 Apr 2023 10:17:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1680887824; x=1683479824; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=npUFrgc9AMRZVGcro/ogjr8k13SD8DOZ44oHkdjV4t4=; b=XMjaFxT4qPJZ/qPHHviVTKJbV7gm8wzXRihKy4mXI07ldiKjeoyNpjqkhIip8Zn2pI V/RhMz4vgx17AnS9Yi1BdKkSu8gX5bBaIZj8JRT7T3vJhmSyJjz5sTr08eBaDx+6VFAV Fk5cMpae1cowigmoO0ouJQpOXNo5MlLmkg0VsUltB/VjjrLz/0xMVZp4Fzzrztz+g2fF LjgMhEB7rOYkV/SsXuOpyNJd4CWWJi7W/fDpNWUa4NImEjPDQvQrQYa2uOYYO6MnMh26 34Ob5cpOYjcF64NzWRRNdfw6DRSB4BUqzvpOZchy0lJLEtH8U2VQ28FuDujmBTSnjwgS 2u/A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680887824; x=1683479824; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=npUFrgc9AMRZVGcro/ogjr8k13SD8DOZ44oHkdjV4t4=; b=q9lVefT4MO+9VP8hplN5wfE2PSNtxO45FgJ12i6PRrmM2XnHv7bQRexSO5vQudd/V+ /0N0j8hiz1EgesVp0RWHXbbERsT7K0UDvJQchfjwhuwLHbNGaLaow98GbgFmHjgfoyFY WcajamsPaHD8TsYM5k/V4dEdYQMiUBcMxxqfzfOBdd0IQcY7/JoksoAkzeDFNdCKpiSN mN2JNBftivmC9kZUvYLZ5v7Pl4zMI+LraEsGqZDgbPHDyi4wMgBlGYvtbPDBUgt9vEqK qZtBV8nhJeGYTjoOjDXEHQSkof0VvL8eIhZTeszHsyhdDZamRpl9lDGBoF7phVeiMJfs JJ2g== X-Gm-Message-State: AAQBX9dhb2OvPvQEEY0ME0zFJHXp0hwJYfvAXzQyJL5gUyg0Hkio08mr 3XrbHV9ZRV4vgvzFjpjetfw= X-Google-Smtp-Source: AKy350Z4ogj2gKuE7PmxSmHZ1tsiSQTaiGrFwRsWzacWeUNk/G2wKxD07oY5isLrlQ7WS1HnJPB9mg== X-Received: by 2002:a17:902:e850:b0:1a5:7ce:2015 with SMTP id t16-20020a170902e85000b001a507ce2015mr4202537plg.16.1680887823869; Fri, 07 Apr 2023 10:17:03 -0700 (PDT) Received: from john.lan ([98.97.116.126]) by smtp.gmail.com with ESMTPSA id p1-20020a1709028a8100b0019b0937003esm3185425plo.150.2023.04.07.10.17.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Apr 2023 10:17:03 -0700 (PDT) From: John Fastabend To: jakub@cloudflare.com, daniel@iogearbox.net, lmb@isovalent.com, edumazet@google.com Cc: john.fastabend@gmail.com, bpf@vger.kernel.org, netdev@vger.kernel.org, ast@kernel.org, andrii@kernel.org, will@isovalent.com Subject: [PATCH bpf v6 04/12] bpf: sockmap, handle fin correctly Date: Fri, 7 Apr 2023 10:16:46 -0700 Message-Id: <20230407171654.107311-5-john.fastabend@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20230407171654.107311-1-john.fastabend@gmail.com> References: <20230407171654.107311-1-john.fastabend@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The sockmap code is returning EAGAIN after a FIN packet is received and no more data is on the receive queue. Correct behavior is to return 0 to the user and the user can then close the socket. The EAGAIN causes many apps to retry which masks the problem. Eventually the socket is evicted from the sockmap because its released from sockmap sock free handling. The issue creates a delay and can cause some errors on application side. To fix this check on sk_msg_recvmsg side if length is zero and FIN flag is set then set return to zero. A selftest will be added to check this condition. Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()") Tested-by: William Findlay Signed-off-by: John Fastabend --- net/ipv4/tcp_bpf.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index ebf917511937..804bd0c247d0 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -174,6 +174,24 @@ static int tcp_msg_wait_data(struct sock *sk, struct sk_psock *psock, return ret; } +static bool is_next_msg_fin(struct sk_psock *psock) +{ + struct scatterlist *sge; + struct sk_msg *msg_rx; + int i; + + msg_rx = sk_psock_peek_msg(psock); + i = msg_rx->sg.start; + sge = sk_msg_elem(msg_rx, i); + if (!sge->length) { + struct sk_buff *skb = msg_rx->skb; + + if (skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) + return true; + } + return false; +} + static int tcp_bpf_recvmsg_parser(struct sock *sk, struct msghdr *msg, size_t len, @@ -196,6 +214,19 @@ static int tcp_bpf_recvmsg_parser(struct sock *sk, lock_sock(sk); msg_bytes_ready: copied = sk_msg_recvmsg(sk, psock, msg, len, flags); + /* The typical case for EFAULT is the socket was gracefully + * shutdown with a FIN pkt. So check here the other case is + * some error on copy_page_to_iter which would be unexpected. + * On fin return correct return code to zero. + */ + if (copied == -EFAULT) { + bool is_fin = is_next_msg_fin(psock); + + if (is_fin) { + copied = 0; + goto out; + } + } if (!copied) { long timeo; int data; -- 2.33.0