From patchwork Fri Jan 15 12:27:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 364543 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 06445C432C3 for ; Fri, 15 Jan 2021 13:04:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFF342256F for ; Fri, 15 Jan 2021 13:04:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733241AbhAONEC (ORCPT ); Fri, 15 Jan 2021 08:04:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:37364 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732762AbhAOMbl (ORCPT ); Fri, 15 Jan 2021 07:31:41 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 434D8239D0; Fri, 15 Jan 2021 12:31:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610713885; bh=1saCcVLhoLc7kxDg4py+J6DxUvLBCh6SIjzoNJqgJD8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YLyBSxd1CYOIQzfAKx/1tCSV/EoFbHq6x628j9TVrFdJWj4DrKWk3CSm/w/vdV1hW df8KsVTin0toUsxmYAiI2Om4nkGoP661Bvct05DjMN2dS7VGULL/6Xfqo3M0WZa6oW aKfqybPNeEQ0/RpldS05M+xoztIdw9SlDE8eeFaU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stefano Brivio , Florian Westphal , Pablo Neira Ayuso , Jakub Kicinski Subject: [PATCH 4.14 05/28] net: fix pmtu check in nopmtudisc mode Date: Fri, 15 Jan 2021 13:27:42 +0100 Message-Id: <20210115121957.006577531@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210115121956.731354372@linuxfoundation.org> References: <20210115121956.731354372@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Florian Westphal [ Upstream commit 50c661670f6a3908c273503dfa206dfc7aa54c07 ] For some reason ip_tunnel insist on setting the DF bit anyway when the inner header has the DF bit set, EVEN if the tunnel was configured with 'nopmtudisc'. This means that the script added in the previous commit cannot be made to work by adding the 'nopmtudisc' flag to the ip tunnel configuration. Doing so breaks connectivity even for the without-conntrack/netfilter scenario. When nopmtudisc is set, the tunnel will skip the mtu check, so no icmp error is sent to client. Then, because inner header has DF set, the outer header gets added with DF bit set as well. IP stack then sends an error to itself because the packet exceeds the device MTU. Fixes: 23a3647bc4f93 ("ip_tunnels: Use skb-len to PMTU check.") Cc: Stefano Brivio Signed-off-by: Florian Westphal Acked-by: Pablo Neira Ayuso Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/ipv4/ip_tunnel.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/net/ipv4/ip_tunnel.c +++ b/net/ipv4/ip_tunnel.c @@ -752,7 +752,11 @@ void ip_tunnel_xmit(struct sk_buff *skb, goto tx_error; } - if (tnl_update_pmtu(dev, skb, rt, tnl_params->frag_off, inner_iph)) { + df = tnl_params->frag_off; + if (skb->protocol == htons(ETH_P_IP) && !tunnel->ignore_df) + df |= (inner_iph->frag_off & htons(IP_DF)); + + if (tnl_update_pmtu(dev, skb, rt, df, inner_iph)) { ip_rt_put(rt); goto tx_error; } @@ -780,10 +784,6 @@ void ip_tunnel_xmit(struct sk_buff *skb, ttl = ip4_dst_hoplimit(&rt->dst); } - df = tnl_params->frag_off; - if (skb->protocol == htons(ETH_P_IP) && !tunnel->ignore_df) - df |= (inner_iph->frag_off&htons(IP_DF)); - max_headroom = LL_RESERVED_SPACE(rt->dst.dev) + sizeof(struct iphdr) + rt->dst.header_len + ip_encap_hlen(&tunnel->encap); if (max_headroom > dev->needed_headroom)