Linux Ethernet Bridging - Apr 2007 - [Bridge] VLAN handling in br_netfilter.c:br_nf_pre_routing

On Tue, 15 Aug 2006 23:31:21 -0400
"Jon Sjoberg" <jsjoberg@djasolutions.com> wrote:
> Hi all,
> 
> Noticed that br_nf_pre_routing has some code to handle VLANs, but does not
> update the nh header.  This appears to cause the IP validity checks to fail
> (i.e. "if (iph->ihl < 5...").
> 
> There is a check:
> if (skb->protocol == __constant_htons(ETH_P_8021Q)){
> sk_pull(skb, VLAN_HLEN);
> }
> 
> If this was changed to:
> if (skb->protocol == __constant_htons(ETH_P_8021Q)){
> sk_pull(skb, VLAN_HLEN);
> skb->nh.raw += VLAN_HLEN;
> }
> 
> the checks pass.  Note that this updated behavior is already doen elsewhere
> in the code.
> 
> Thanks,
> Jon
You are looking at old code, it was fixed in the current 2.6 tree.
The skb_pull had to be changed to skb_pull_rcsum as well.

Hi all,

Noticed that br_nf_pre_routing has some code to handle VLANs, but does not
update the nh header.  This appears to cause the IP validity checks to fail
(i.e. "if (iph->ihl < 5...").

There is a check:
if (skb->protocol == __constant_htons(ETH_P_8021Q)){
sk_pull(skb, VLAN_HLEN);
}

If this was changed to:
if (skb->protocol == __constant_htons(ETH_P_8021Q)){
sk_pull(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}

the checks pass.  Note that this updated behavior is already doen elsewhere
in the code.

Thanks,
Jon
----------------------------------------------------------------
Jon Sjoberg
DJA Solutions
E-mail: jsjoberg@djasolutions.com
Phone: 978.448.3659