Re: [PATCH V2 2/2] ipvs: Extend MTU check to account for IPv6 NAT defrag changes

Eric Dumazet
2012-08-28T14:49:19Z

On Tue, 2012-08-28 at 16:23 +0200, 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>
> ---
> In V2: the tunnel mode is no longer a special case.
>
> net/netfilter/ipvs/ip_vs_xmit.c | 9 ++++++++-
> 1 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
> index 67a3978..56f6d5d 100644
> --- a/net/netfilter/ipvs/ip_vs_xmit.c
> +++ b/net/netfilter/ipvs/ip_vs_xmit.c
> @@ -88,7 +88,14 @@ __ip_vs_dst_check(struct ip_vs_dest *dest, u32 rtos)
> static inline bool
> __mtu_check_toobig_v6(const struct sk_buff *skb, u32 mtu)
> {
> - if (skb->len > mtu && !skb_is_gso(skb)) {
> + if (IP6CB(skb)->frag_max_size) {
> + /* frag_max_size tell us that, this packet have been
> + * defragmented by netfilter IPv6 conntrack module.
> + */
> + if (IP6CB(skb)->frag_max_size > mtu)
> + return true; /* largest fragment violate MTU */
> + }
> + else if (skb->len > mtu && !skb_is_gso(skb)) {
> return true; /* Packet size violate MTU size */
> }

Couldnt you use a single test ?

if (IP6CB(skb)->frag_max_size > mtu)
return true;

if (skb->len > mtu && !skb_is_gso(skb))
return true;