vti6: Add pmtu handling to vti6_xmit.

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 <[email protected]> Signed-off-by: Alexander Duyck <[email protected]> Signed-off-by: David S. Miller <[email protected]>
mrcsosa · Jun 1, 2015 · ccd740c · ccd740c
1 parent 18ec898
commit ccd740c
Showing 1 changed file with 14 additions and 0 deletions.
diff --git 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);