Re: PROBLEM: Software injected vlan tagged packets are unable to be identified using recent BPF modifications

[Ani Sinha <ani () aristanetworks com>]

On Mon, Jan 7, 2013 at 4:05 PM, Paul Pearce <pearce () cs berkeley edu> wrote:
> Hello folks,
>
> PROBLEM:
>
> vlan tagged packets that are injected via software are not picked up
> by filters using recent (kernel commit
> f3335031b9452baebfe49b8b5e55d3fe0c4677d1)
> BPF vlan modifications. I suspect this is a problem with the Linux
> kernel.
>
> linux-netdev and tcpdump-workers are both cc'd.

Just to be clear, up until now we did not see this issue because the
BPF filter code generated by libpcap would always look into packet
offsets for vlan tag information. With the patch that I submitted to
tcpdump-workers a day ago, it no longer looks into the packet but in
the skb meta data (which is the right thing to do going forward). This
breaks raw packets. We will have to handle this in the kernel to fix
it.

ani
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