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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 B9DF0C282DD for ; Wed, 8 Jan 2020 18:17:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9A88320678 for ; Wed, 8 Jan 2020 18:17:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728474AbgAHSRy (ORCPT ); Wed, 8 Jan 2020 13:17:54 -0500 Received: from www62.your-server.de ([213.133.104.62]:55474 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727507AbgAHSRy (ORCPT ); Wed, 8 Jan 2020 13:17:54 -0500 Received: from sslproxy06.your-server.de ([78.46.172.3]) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1ipFtw-0008N1-I5; Wed, 08 Jan 2020 19:17:52 +0100 Received: from [2001:1620:665:0:5795:5b0a:e5d5:5944] (helo=linux-3.fritz.box) by sslproxy06.your-server.de with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1ipFtw-000387-9i; Wed, 08 Jan 2020 19:17:52 +0100 Subject: Re: [PATCH] bpf/sockmap: read psock ingress_msg before sk_receive_queue To: John Fastabend , Lingpeng Chen Cc: netdev@vger.kernel.org, bpf@vger.kernel.org References: <5e15526d2ebb6_68832ae93d7145c08c@john-XPS-13-9370.notmuch> <20200108045708.31240-1-forrest0579@gmail.com> <20200108170259.GA7665@linux-3.fritz.box> <5e161913342f2_67ea2afd262665bc1c@john-XPS-13-9370.notmuch> From: Daniel Borkmann Message-ID: Date: Wed, 8 Jan 2020 19:17:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <5e161913342f2_67ea2afd262665bc1c@john-XPS-13-9370.notmuch> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.101.4/25688/Wed Jan 8 10:56:24 2020) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 1/8/20 7:01 PM, John Fastabend wrote: > Daniel Borkmann wrote: >> On Wed, Jan 08, 2020 at 12:57:08PM +0800, Lingpeng Chen wrote: >>> Right now in tcp_bpf_recvmsg, sock read data first from sk_receive_queue >>> if not empty than psock->ingress_msg otherwise. If a FIN packet arrives >>> and there's also some data in psock->ingress_msg, the data in >>> psock->ingress_msg will be purged. It is always happen when request to a >>> HTTP1.0 server like python SimpleHTTPServer since the server send FIN >>> packet after data is sent out. >>> >>> Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface") >>> Reported-by: Arika Chen >>> Suggested-by: Arika Chen >>> Signed-off-by: Lingpeng Chen >>> Signed-off-by: John Fastabend >>> --- >>> net/ipv4/tcp_bpf.c | 7 ++++--- >>> 1 file changed, 4 insertions(+), 3 deletions(-) >>> >>> diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c >>> index e38705165ac9..f7e902868fce 100644 >>> --- a/net/ipv4/tcp_bpf.c >>> +++ b/net/ipv4/tcp_bpf.c >>> @@ -123,12 +123,13 @@ int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, >>> >>> if (unlikely(flags & MSG_ERRQUEUE)) >>> return inet_recv_error(sk, msg, len, addr_len); >> >> Shouldn't we also move the error queue handling below the psock test as >> well and let tcp_recvmsg() natively do it in case of !psock? >> > > You mean the MSG_ERRQUEUE flag handling? If the user sets MSG_ERRQUEUE > they expect to receive any queued errors it would be wrong to return > psock data in this case if psock is attached and has data on queue and > user passes MSG_ERRQUEUE flag. > > MSG_ERRQUEUE (since Linux 2.2) > This flag specifies that queued errors should be received from the socket > error queue. The error is passed in an ancillary message with a type > dependent on the protocol (for IPv4 IP_RECVERR). The user should supply > a buffer of sufficient size. See cmsg(3) and ip(7) for more information. > The payload of the original packet that caused the error is passed as > normal data via msg_iovec. The original destination address of the > datagram that caused the error is supplied via msg_name. > > I believe it needs to be where it is. I meant that it should have looked as follows (aka moving both below the psock test) ... psock = sk_psock_get(sk); if (unlikely(!psock)) return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); if (unlikely(flags & MSG_ERRQUEUE)) return inet_recv_error(sk, msg, len, addr_len); if (!skb_queue_empty(&sk->sk_receive_queue) && [...] ... since when detached it's handled already via tcp_recvmsg() internals. >>> - if (!skb_queue_empty(&sk->sk_receive_queue)) >>> - return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); >>> >>> psock = sk_psock_get(sk); >>> if (unlikely(!psock)) >>> return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); >>> + if (!skb_queue_empty(&sk->sk_receive_queue) && >>> + sk_psock_queue_empty(psock)) >>> + return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); >>> lock_sock(sk); >>> msg_bytes_ready: >>> copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags); >>> @@ -139,7 +140,7 @@ int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, >>> timeo = sock_rcvtimeo(sk, nonblock); >>> data = tcp_bpf_wait_data(sk, psock, flags, timeo, &err); >>> if (data) { >>> - if (skb_queue_empty(&sk->sk_receive_queue)) >>> + if (!sk_psock_queue_empty(psock)) >>> goto msg_bytes_ready; >>> release_sock(sk); >>> sk_psock_put(sk, psock); >>> -- >>> 2.17.1 >>> > >