Commit 5f379ef5 authored Aug 02, 2018 by Georg Kohmann Committed by David S. Miller Aug 05, 2018

ipv6: icmp: Updating pmtu for link local route



When a ICMPV6_PKT_TOOBIG is received from a link local address the pmtu will
be updated on a route with an arbitrary interface index. Subsequent packets
sent back to the same link local address may therefore end up not
considering the updated pmtu.

Current behavior breaks TAHI v6LC4.1.4 Reduce PMTU On-link. Referring to RFC
1981: Section 3: "Note that Path MTU Discovery must be performed even in
cases where a node "thinks" a destination is attached to the same link as
itself. In a situation such as when a neighboring router acts as proxy [ND]
for some destination, the destination can to appear to be directly
connected but is in fact more than one hop away."

Using the interface index from the incoming ICMPV6_PKT_TOOBIG when updating
the pmtu.

Signed-off-by: Georg Kohmann <geokohma@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 91305f28

net/ipv6/icmp.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -92,7 +92,7 @@ static void icmpv6_err(struct sk_buff skb, struct inet6_skb_parm opt,
		struct net *net = dev_net(skb->dev);

		if (type == ICMPV6_PKT_TOOBIG)
		ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
		ip6_update_pmtu(skb, net, info, skb->dev->ifindex, 0, sock_net_uid(net, NULL));
		else if (type == NDISC_REDIRECT)
		ip6_redirect(skb, net, skb->dev->ifindex, 0,
		sock_net_uid(net, NULL));

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