From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steffen Klassert Subject: [PATCH 3/3] vti: Add pmtu handling to vti_xmit. Date: Wed, 4 May 2016 07:40:54 +0200 Message-ID: <1462340454-27922-4-git-send-email-steffen.klassert@secunet.com> References: <1462340454-27922-1-git-send-email-steffen.klassert@secunet.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Herbert Xu , Steffen Klassert , To: David Miller Return-path: Received: from a.mx.secunet.com ([62.96.220.36]:56700 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751383AbcEDFlL (ORCPT ); Wed, 4 May 2016 01:41:11 -0400 In-Reply-To: <1462340454-27922-1-git-send-email-steffen.klassert@secunet.com> Sender: netdev-owner@vger.kernel.org List-ID: We currently rely on the PMTU discovery of xfrm. However if a packet is locally sent, the PMTU mechanism of xfrm tries to do local socket notification what might not work for applications like ping that don't check for this. So add pmtu handling to vti_xmit to report MTU changes immediately. Reported-by: Mark McKinstry Signed-off-by: Steffen Klassert --- net/ipv4/ip_vti.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c index 5cf10b7..a917903 100644 --- a/net/ipv4/ip_vti.c +++ b/net/ipv4/ip_vti.c @@ -156,6 +156,7 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev, struct dst_entry *dst = skb_dst(skb); struct net_device *tdev; /* Device to other host */ int err; + int mtu; if (!dst) { dev->stats.tx_carrier_errors++; @@ -192,6 +193,23 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev, tunnel->err_count = 0; } + mtu = dst_mtu(dst); + if (skb->len > mtu) { + skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu); + if (skb->protocol == htons(ETH_P_IP)) { + icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, + htonl(mtu)); + } else { + if (mtu < IPV6_MIN_MTU) + mtu = IPV6_MIN_MTU; + + icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); + } + + dst_release(dst); + goto tx_error; + } + skb_scrub_packet(skb, !net_eq(tunnel->net, dev_net(dev))); skb_dst_set(skb, dst); skb->dev = skb_dst(skb)->dev; -- 1.9.1