Commit b881ef76 authored by John Heffner's avatar John Heffner Committed by David S. Miller

[IPV6]: MTU discovery check in ip6_fragment()

Adds a check in ip6_fragment() mirroring ip_fragment() for packets
that we can't fragment, and sends an ICMP Packet Too Big message
in response.
Signed-off-by: default avatarJohn Heffner <>
Signed-off-by: default avatarDavid S. Miller <>
parent fd44de7c
......@@ -567,6 +567,19 @@ static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
nexthdr = *prevhdr;
mtu = dst_mtu(&rt->u.dst);
/* We must not fragment if the socket is set to force MTU discovery
* or if the skb it not generated by a local socket. (This last
* check should be redundant, but it's free.)
if (!np || np->pmtudisc >= IPV6_PMTUDISC_DO) {
skb->dev = skb->dst->dev;
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGFAILS);
return -EMSGSIZE;
if (np && np->frag_size < mtu) {
if (np->frag_size)
mtu = np->frag_size;
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment