From d6af1a31cc72fbd558c7eddbc36f61bf09d1cf6a Mon Sep 17 00:00:00 2001 From: Steffen Klassert Date: Wed, 16 Mar 2016 10:17:37 +0100 Subject: [PATCH] vti: Add pmtu handling to vti_xmit. 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 5cf10b777b7e..a917903d5e97 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; -- 2.20.1