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 E9721C433FE for ; Wed, 4 May 2022 14:47:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351490AbiEDOu5 (ORCPT ); Wed, 4 May 2022 10:50:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36986 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348352AbiEDOu4 (ORCPT ); Wed, 4 May 2022 10:50:56 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 835A520F5F for ; Wed, 4 May 2022 07:47:20 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0C5D361ABC for ; Wed, 4 May 2022 14:47:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34828C385A4; Wed, 4 May 2022 14:47:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651675639; bh=PLZXDj27tTjL0KPBU5yjckijQTuSmMtJCHBpBr5Pj1U=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=GM2UL9fG2R1TBQNIAuwbyydG9PLKizmOgCfBO+5ZShGxuxpr4mpBWG64QJz86poQE mcTKXMB9kcN9y7BgNHzyfuoQEr0CBkU5NQYL75YXewPVN2qvLOYO2A5TN7RdkqPff4 dqkICd2ULPcZi5x21tltXxG4CfObGcQuntUpEFt7G/zHr4Zh4kPEG061H1ZgSgbfmi s66swfKqaPtTuCk9YNP/r1D/tUwi6YpEKzjGzLhLwaSZqrRkGbycaDbLBoIynSXwT4 q2B/jX2YVm4bM8KwnkaqUfWUHLuYTx3pJu8gBKcuQYtLJSruDsJlL8c0pNJpWMDkNG TwVFJ5VDVLExw== Date: Wed, 4 May 2022 07:47:18 -0700 From: Jakub Kicinski To: Paolo Abeni Cc: Jamal Hadi Salim , netdev@vger.kernel.org, Cong Wang , Jiri Pirko Subject: Re: [PATCH net] net/sched: act_pedit: really ensure the skb is writable Message-ID: <20220504074718.146a5724@kernel.org> In-Reply-To: References: <6c1230ee0f348230a833f92063ff2f5fbae58b94.1651584976.git.pabeni@redhat.com> <7e4682da-6ed6-17cf-8e5a-dff7925aef1d@mojatatu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 04 May 2022 10:52:59 +0200 Paolo Abeni wrote: > On Tue, 2022-05-03 at 16:10 -0400, Jamal Hadi Salim wrote: > > What was the tc pedit command that triggered this? > > From the mptcp self-tests, mptcp_join.sh: > > tc -n $ns2 filter add dev ns2eth$i egress \ > protocol ip prio 1000 \ > handle 42 fw \ > action pedit munge offset 148 u8 invert \ > pipe csum tcp \ > index 100 || exit 1 > > It's used to corrupt a packet so that TCP csum is still correct while > the MPTCP one is not. > > The relevant part is that the touched offset is outside the skb head. > > > Can we add it to tdc tests? > > What happens in the mptcp self-tests it that an almost simultaneous > mptcp-level reinjection on another device using the same cloned data > get unintentionally corrupted and we catch it - when it sporadically > happens - via the MPTCP mibs. > > While we could add the above pedit command, but I fear that a > meaningful test for the issue addressed here not fit the tdc > infrastructure easily. For testing stuff like this would it be possible to inject packets with no headers pulled and frags in pages we marked read-only? We can teach netdevsim to do it. Obviously not as a pre-requisite for this patch.