From: Alexander Duyck Subject: [PATCH] vti6: Add pmtu handling to vti6_xmit. Date: Fri, 29 May 2015 11:28:26 -0700 Message-ID: <20150529182709.2147.78230.stgit@ahduyck-vm-fedora22> References: <5567695F.6070505@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-crypto@vger.kernel.org To: steffen.klassert@secunet.com, davem@davemloft.net, herbert@gondor.apana.org.au Return-path: Received: from mx1.redhat.com ([209.132.183.28]:39349 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161065AbbE2S22 (ORCPT ); Fri, 29 May 2015 14:28:28 -0400 In-Reply-To: <5567695F.6070505@gmail.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: From: Steffen Klassert We currently rely on the PMTU discovery of xfrm. However if a packet is localy sent, the PMTU mechanism of xfrm tries to to local socket notification what might not work for applications like ping that don't check for this. So add pmtu handling to vti6_xmit to report MTU changes immediately. Signed-off-by: Steffen Klassert Signed-off-by: Alexander Duyck --- So this version is slightly modified to cover the IPv4 case in addition to the IPv6 case. With this patch I was able to run netperf over either an IPv4 or IPv6 address routed over the ip6_vti tunnel. net/ipv6/ip6_vti.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c index d25209657edc..3b5c1ea50d2f 100644 --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -435,6 +435,7 @@ vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl) struct net_device *tdev; struct xfrm_state *x; int err = -1; + int mtu; if (!dst) goto tx_err_link_failure; @@ -468,6 +469,19 @@ vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl) skb_dst_set(skb, dst); skb->dev = skb_dst(skb)->dev; + mtu = dst_mtu(dst); + if (!skb->ignore_df && skb->len > mtu) { + skb_dst(skb)->ops->update_pmtu(dst, NULL, skb, mtu); + + if (skb->protocol == htons(ETH_P_IPV6)) + icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); + else + icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, + htonl(mtu)); + + return -EMSGSIZE; + } + err = dst_output(skb); if (net_xmit_eval(err) == 0) { struct pcpu_sw_netstats *tstats = this_cpu_ptr(dev->tstats);