Florian Westphal <fw@xxxxxxxxx> wrote:
> consider a bridge with mtu 9000, but end host sending smaller
> packets to another host with mtu < 9000.
>
> In this case, after reassembly, bridge+defrag would refragment,
> and then attempt to send the reassembled packet as long as it
> was below 9k.
>
> Instead we have to cap by the largest fragment size seen.
>
> Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
> ---
> No Fixes tag, seems this problem has always existed.
> tested in kvm with both ipv4 and ipv6 and following setup:
>
> client (mtu 1500) --- bridge(mtu 9k) --- client (mtu 1500)
>
> bridge (incl. all ports) have 9k mtu.
>
> without this patch, ping/ping6 only works for sizes <= 1500
> and > 9000.
grrr. it breaks the normal path...
> diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
> index 95087e6e8258..81889afee212 100644
> --- a/net/bridge/br_netfilter_hooks.c
> +++ b/net/bridge/br_netfilter_hooks.c
> @@ -721,18 +721,19 @@ static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb)
>
> static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
> {
> - struct nf_bridge_info *nf_bridge;
> - unsigned int mtu_reserved;
> + struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
> + unsigned int mtu, mtu_reserved;
>
> mtu_reserved = nf_bridge_mtu_reduction(skb);
> + mtu = nf_bridge->frag_max_size;
This can be 0, I'll send a v2.
--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
