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 <[email protected]>
Signed-off-by: Steffen Klassert <[email protected]>
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 @@
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 @@
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;
