Re: [PATCH 2/2] ipvs: Extend MTU check to account for IPv6 NAT defrag changes

Jesper Dangaard Brouer
2012-08-28T09:03:27Z

On Mon, 2012-08-27 at 18:20 +0300, Julian Anastasov wrote:
> Hello,
>
> On Mon, 27 Aug 2012, Jesper Dangaard Brouer wrote:
>
> > This patch is necessary, to make IPVS work, after Patrick McHardys
> > IPv6 NAT defragmentation changes.
> >
> > Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
> > ---
> >
> > I would appriciate, if someone (e.g. Julian) double check the tunnel mode code.
>
> Sure
>
> > --Jesper
> >
> > net/netfilter/ipvs/ip_vs_xmit.c | 16 +++++++++++++---
> > 1 files changed, 13 insertions(+), 3 deletions(-)
> >
> > @@ -956,8 +963,11 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
> > skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
> >
> > /* MTU checking: Special for tunnel mode */
> > - if (mtu < ntohs(old_iph->payload_len) + sizeof(struct ipv6hdr) &&

I guess:
ntohs(old_iph->payload_len) + sizeof(struct ipv6hdr)
Is the same as:
skb->len

> > - !skb_is_gso(skb)) {
> > + if ((!IP6CB(skb)->frag_max_size &&
> > + (mtu < ntohs(old_iph->payload_len) + sizeof(struct ipv6hdr) &&
> > + !skb_is_gso(skb)))
> > + || IP6CB(skb)->frag_max_size + sizeof(struct ipv6hdr) > mtu) {

>
> mtu is already reduced with the new outer header size,
> may be we can just call __mtu_check_toobig_v6 with mtu?

To Julian, is the extra sizeof(struct ipv6hdr) addition to
frag_max_size, wrong? (as the mtu is already reduced)

If above statements hold, I think we can simply use
__mtu_check_toobig_v6() also for the tunnel case :-)

--Jesper