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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,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 B2585C43387 for ; Thu, 17 Jan 2019 23:55:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A88220851 for ; Thu, 17 Jan 2019 23:55:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727018AbfAQXz3 (ORCPT ); Thu, 17 Jan 2019 18:55:29 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:34324 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726008AbfAQXz3 (ORCPT ); Thu, 17 Jan 2019 18:55:29 -0500 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::bf5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 5A17714B98824; Thu, 17 Jan 2019 15:55:28 -0800 (PST) Date: Thu, 17 Jan 2019 15:55:27 -0800 (PST) Message-Id: <20190117.155527.717258097202066512.davem@davemloft.net> To: nicolas.dichtel@6wind.com Cc: netdev@vger.kernel.org, willemb@google.com, maximmi@mellanox.com Subject: Re: [PATCH net v2] af_packet: fix raw sockets over 6in4 tunnel From: David Miller In-Reply-To: <20190117102722.14474-1-nicolas.dichtel@6wind.com> References: <20190117102722.14474-1-nicolas.dichtel@6wind.com> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 17 Jan 2019 15:55:28 -0800 (PST) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Nicolas Dichtel Date: Thu, 17 Jan 2019 11:27:22 +0100 > Since commit cb9f1b783850, scapy (which uses an AF_PACKET socket in > SOCK_RAW mode) is unable to send a basic icmp packet over a sit tunnel: > > Here is a example of the setup: > $ ip link set ntfp2 up > $ ip addr add 10.125.0.1/24 dev ntfp2 > $ ip tunnel add tun1 mode sit ttl 64 local 10.125.0.1 remote 10.125.0.2 dev ntfp2 > $ ip addr add fd00:cafe:cafe::1/128 dev tun1 > $ ip link set dev tun1 up > $ ip route add fd00:200::/64 dev tun1 > $ scapy >>>> p = [] >>>> p += IPv6(src='fd00:100::1', dst='fd00:200::1')/ICMPv6EchoRequest() >>>> send(p, count=1, inter=0.1) >>>> quit() > $ ip -s link ls dev tun1 | grep -A1 "TX.*errors" > TX: bytes packets errors dropped carrier collsns > 0 0 1 0 0 0 > > The problem is that the network offset is set to the hard_header_len of the > output device (tun1, ie 14 + 20) and in our case, because the packet is > small (48 bytes) the pskb_inet_may_pull() fails (it tries to pull 40 bytes > (ipv6 header) starting from the network offset). > > This problem is more generally related to device with variable hard header > length. To avoid a too intrusive patch in the current release, a (ugly) > workaround is proposed in this patch. It has to be cleaned up in net-next. > > Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=993675a3100b1 > Link: http://patchwork.ozlabs.org/patch/1024489/ > Fixes: cb9f1b783850 ("ip: validate header length on virtual device xmit") > CC: Willem de Bruijn > CC: Maxim Mikityanskiy > Signed-off-by: Nicolas Dichtel > --- > > v1 -> v2: > reset nh offset only for small packets sent on a variable hard hdr len device Applied.