On Fri, 25 May 2007 10:17:50 +0200
Adam Osuchowski <adwol@xxxxxxx> wrote:
> There is a problem with fragmented IP packet sent within 802.1Q tagged
> ethernet frame through bridge. Problem exists when conntrack is enabled
> (i.e. nf_conntrack_ipv4 module is loaded). Then, such packets are not
> fragmented again (after prior reassembling on bridge device) during
> passing it to bridge enslaved NIC. It cause MTU exceeding and as a result
> dropping packet.
>
> Problem exists from kernel version 2.6.17 to 2.6.21.3 inclusive.
>
> Below, there is a patch to fix it.
>
> Regards.
>
>
> --- linux-2.6.21.3.orig/net/bridge/br_netfilter.c 2007-05-25 09:56:15.000000000 +0200
> +++ linux-2.6.21.3/net/bridge/br_netfilter.c 2007-05-25 10:11:42.000000000 +0200
> @@ -731,7 +731,7 @@
>
> static int br_nf_dev_queue_xmit(struct sk_buff *skb)
> {
> - if (skb->protocol == htons(ETH_P_IP) &&
> + if ((skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb)) &&
> skb->len > skb->dev->mtu &&
> !skb_is_gso(skb))
> return ip_fragment(skb, br_dev_queue_push_xmit);
It would be better to account for the tag in the length check.
Something like
if (skb->protocol == htons(ETH_P_IP) &&
skb->len > skb->dev->mtu - (IS_VLAN_IP(skb) ? VLAN_HLEN : 0) &&
!skb_is_gso(skb))
return ip_fragment ...
--
Stephen Hemminger <shemminger@xxxxxxxxxxxxxxxxxxxx>
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