[Bridge] [BUG] Dropping fragmented IP packets within VLAN
frames on bridge
Stephen Hemminger
shemminger at linux-foundation.org
Fri May 25 11:00:13 PDT 2007
On Fri, 25 May 2007 19:49:25 +0200
Adam Osuchowski <adwol at zonk.pl> wrote:
> Stephen Hemminger wrote:
> > 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 ...
>
> It isn't good solution because one of IS_VLAN_IP() necessary condition is
>
> skb->protocol == htons(ETH_P_8021Q)
>
> which is, of course, mutually exclusive with
>
> skb->protocol == htons(ETH_P_IP)
>
> from br_nf_dev_queue_xmit(). IMHO, one should check length of ETH_P_IP
> and ETH_P_8021Q frames separately:
>
> if (((skb->protocol == htons(ETH_P_IP) && skb->len > skb->dev->mtu) ||
> (IS_VLAN_IP(skb) && skb->len > skb->dev->mtu - VLAN_HLEN)) &&
> !skb_is_gso(skb))
> return ip_fragment ...
There is a function in br_forward.c that handles VLAN packet length
maybe use that
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