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=-1.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED 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 76EB1C10F0E for ; Thu, 18 Apr 2019 12:02:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3C92B2183E for ; Thu, 18 Apr 2019 12:02:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="YXVo9k6F" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388896AbfDRMCC (ORCPT ); Thu, 18 Apr 2019 08:02:02 -0400 Received: from mail-oi1-f180.google.com ([209.85.167.180]:40050 "EHLO mail-oi1-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388686AbfDRMCB (ORCPT ); Thu, 18 Apr 2019 08:02:01 -0400 Received: by mail-oi1-f180.google.com with SMTP id f196so1381220oib.7 for ; Thu, 18 Apr 2019 05:02:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=mwOA7MCLceKP2ikMwqM6FJhE49lGJ+2E7rn+lLHTXsM=; b=YXVo9k6FhnYcIb7fNqNfPhiDBUe6AtUkKMI2dMi8CKgNyGjacmMfnCaA+DEXWViwEM lr3MoIpHmGYHZqC6JhxdjqR2TU4nLkUznN6xnfI6qpCWJMVk+KSB1KOSj7qwfZbNqXPp i2fZCD2piRY/IcHHop3U4RWuT72uVPFaImZac= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=mwOA7MCLceKP2ikMwqM6FJhE49lGJ+2E7rn+lLHTXsM=; b=FRk46G3T7hLuTSClFHYIHEO+YAEMwzH4Wosyi99EiyDJeIj/3g3nqW24PiFCMWOAQ8 DIHFBsQsGo9v38GCpRKecOpTcehkHP867AuHVAsBl2xWG+yZtg8S8tsLbFiRiZNdhDSM hB9d5hVKScDnR6aLmMmV19LaWcTvUgg85GrBViqUPlaPRd49rdJmCmq0PhQUZsRGyh0P b75czmcL2y0URMjjF42fRkwJoyVIQd1iUe009q36mAur7+k3Lfr5htkXaE38mTah+Ogp zIumvuJ81KUYWk1ElOu2SB9ty7JzV3nrGJm3GjTFF1Lhqa6hX4zYnWq4qX/hxRoxSWpk vQTQ== X-Gm-Message-State: APjAAAXzQJniQivxJpLmX9XtnyqnGrLW/3ibAWcT7ELb8mmEqiIk6PtR Q0G7E9s3ekt8uQFCcoqBseF2QvZwYghZccR2KI2MSbNnmJBMkA== X-Google-Smtp-Source: APXvYqz7BeVQSwoTxxJnaCVdmhC2CRmBNg3qJYdLCcGTGVh76Mr628SLII7+79lFDUl/whgKOSaatASfXNcSbsdELdo= X-Received: by 2002:aca:d482:: with SMTP id l124mr1542433oig.102.1555588921012; Thu, 18 Apr 2019 05:02:01 -0700 (PDT) MIME-Version: 1.0 References: <20190416150002.cbkih4lfrna4ywdu@breakpoint.cc> In-Reply-To: <20190416150002.cbkih4lfrna4ywdu@breakpoint.cc> From: Lorenz Bauer Date: Thu, 18 Apr 2019 14:01:49 +0200 Message-ID: Subject: Re: Question re. skb_orphan for TPROXY To: Florian Westphal Cc: herbert@gondor.apana.org.au, netdev@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hello Florian, Thank you, that makes sense. I guess that technically early demux also relies on the skb_orphan call to function? I think that's what confused me. Best Lorenz On Tue, 16 Apr 2019 at 17:00, Florian Westphal wrote: > > Lorenz Bauer wrote: > > Apologies for contacting you out of the blue. I'm currently trying to > > understand how TPROXY works under the hood. As part of this endeavour, > > I've stumbled upon the commit attached to this email. > > > > From the commit message I infer that somewhere, TPROXY relies on a > > check of skb->sk == NULL to function. However, I can't figure out > > where! I've traced TPROXY from NF_HOOK(NF_INET_PRE_ROUTING) just after > > the call to skb_orphan to __inet_lookup_skb / skb_steal_sock called > > from the TCP and UDP receive functions, and as far as I can tell there > > is no such check. Can you maybe shed some light on this? > > Without the skb_orphan udp/tcp might steal tunnel/ppp etc. socket > instead of tproxy assigned tcp/udp socket. -- Lorenz Bauer | Systems Engineer 25 Lavington St., London SE1 0NZ www.cloudflare.com