Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752840AbdLMLVG (ORCPT ); Wed, 13 Dec 2017 06:21:06 -0500 Received: from ec2-13-54-119-68.ap-southeast-2.compute.amazonaws.com ([13.54.119.68]:58080 "EHLO mail.hermana.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752274AbdLMLVD (ORCPT ); Wed, 13 Dec 2017 06:21:03 -0500 X-Greylist: delayed 352 seconds by postgrey-1.27 at vger.kernel.org; Wed, 13 Dec 2017 06:21:03 EST From: Brendan McGrath To: "David S . Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Brendan McGrath Subject: [PATCH] ipv6: ip6mr: Recalc UDP checksum before forwarding Date: Wed, 13 Dec 2017 22:20:48 +1100 Message-Id: <1513164048-21368-1-git-send-email-redmcg@redmandi.dyndns.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1261 Lines: 42 Currently, when forwarding from a Virtual Interface to a Physical Interface, ip_summed is set to a value of CHECKSUM_UNNECESSARY and the UDP checksum has not been calculated. When the packet is then forwarded by a Multicast Router, the checksum value is left as is and therefore rejected by the receiving machine(s). This patch ensures the checksum is recalculated before forwarding. Signed-off-by: Brendan McGrath --- It's a bit ugly putting UDP specific code in this spot - but I'm not aware of any other protocols that are: a) multicast; b) forwarded; and c) checksummed net/ipv6/ip6mr.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c index 890f9bda..ee4370a 100644 --- a/net/ipv6/ip6mr.c +++ b/net/ipv6/ip6mr.c @@ -2077,6 +2077,13 @@ static int ip6mr_forward2(struct net *net, struct mr6_table *mrt, ipv6h = ipv6_hdr(skb); ipv6h->hop_limit--; + if (ipv6h->nexthdr == NEXTHDR_UDP && + skb->ip_summed != CHECKSUM_PARTIAL) { + struct udphdr *uh = udp_hdr(skb); + udp6_set_csum(false, skb, &ipv6_hdr(skb)->saddr, + &ipv6_hdr(skb)->daddr, ntohs(uh->len)); + } + IP6CB(skb)->flags |= IP6SKB_FORWARDED; return NF_HOOK(NFPROTO_IPV6, NF_INET_FORWARD, -- 2.7.4