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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 B7263CA90AF for ; Wed, 13 May 2020 09:47:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 97C442492E for ; Wed, 13 May 2020 09:47:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589363261; bh=fhNrhicOFpTPi5d4hyZ4np9bnClrHaWnKQSRWxqvbFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=cAApHdzPtq7OVKgr5yru0oXZ5pcBDvVvfpbAAbGrJaj++aW6WWkt1XSHh7I+JBqXL 8w26OY70Ht8sH0r59F3U5Eqt7BOhGC/KT7NmU3sYFvWwqCw705l/zvR/C3HS/c6suw LvQFUMICzygpPi3Uqw0MMY5sd/UQZKBL/UMiCKjQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732902AbgEMJrk (ORCPT ); Wed, 13 May 2020 05:47:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:45346 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732856AbgEMJrZ (ORCPT ); Wed, 13 May 2020 05:47:25 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6C6FD20769; Wed, 13 May 2020 09:47:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589363244; bh=fhNrhicOFpTPi5d4hyZ4np9bnClrHaWnKQSRWxqvbFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OoO+qGREg+K0OyExCbCntt/fqFY0axSmv/ifa4hzfseq0D2cZCKpjPC1GFbMRche2 oBMFD0N+8KMK+PqdsfGZi+y2RPLhzRWzphW1KEf5A26/D5YTKRQRyB5JUM2jnK6Az7 m6t2BDP7h08hQK9LwoHCwAFQFYDu7YLg4JPpmBII= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guillaume Nault , Florian Westphal , Pablo Neira Ayuso Subject: [PATCH 4.19 44/48] netfilter: nat: never update the UDP checksum when its 0 Date: Wed, 13 May 2020 11:45:10 +0200 Message-Id: <20200513094403.869182531@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200513094351.100352960@linuxfoundation.org> References: <20200513094351.100352960@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Guillaume Nault commit ea64d8d6c675c0bb712689b13810301de9d8f77a upstream. If the UDP header of a local VXLAN endpoint is NAT-ed, and the VXLAN device has disabled UDP checksums and enabled Tx checksum offloading, then the skb passed to udp_manip_pkt() has hdr->check == 0 (outer checksum disabled) and skb->ip_summed == CHECKSUM_PARTIAL (inner packet checksum offloaded). Because of the ->ip_summed value, udp_manip_pkt() tries to update the outer checksum with the new address and port, leading to an invalid checksum sent on the wire, as the original null checksum obviously didn't take the old address and port into account. So, we can't take ->ip_summed into account in udp_manip_pkt(), as it might not refer to the checksum we're acting on. Instead, we can base the decision to update the UDP checksum entirely on the value of hdr->check, because it's null if and only if checksum is disabled: * A fully computed checksum can't be 0, since a 0 checksum is represented by the CSUM_MANGLED_0 value instead. * A partial checksum can't be 0, since the pseudo-header always adds at least one non-zero value (the UDP protocol type 0x11) and adding more values to the sum can't make it wrap to 0 as the carry is then added to the wrapped number. * A disabled checksum uses the special value 0. The problem seems to be there from day one, although it was probably not visible before UDP tunnels were implemented. Fixes: 5b1158e909ec ("[NETFILTER]: Add NAT support for nf_conntrack") Signed-off-by: Guillaume Nault Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman --- net/netfilter/nf_nat_proto_udp.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/net/netfilter/nf_nat_proto_udp.c +++ b/net/netfilter/nf_nat_proto_udp.c @@ -66,15 +66,14 @@ static bool udp_manip_pkt(struct sk_buff enum nf_nat_manip_type maniptype) { struct udphdr *hdr; - bool do_csum; if (!skb_make_writable(skb, hdroff + sizeof(*hdr))) return false; hdr = (struct udphdr *)(skb->data + hdroff); - do_csum = hdr->check || skb->ip_summed == CHECKSUM_PARTIAL; + __udp_manip_pkt(skb, l3proto, iphdroff, hdr, tuple, maniptype, + !!hdr->check); - __udp_manip_pkt(skb, l3proto, iphdroff, hdr, tuple, maniptype, do_csum); return true; }