[ieee80211] [patch] BPF taps not working for ieee80211 interfaces in monitor mode

[Adrian Chadd]

On 9 October 2013 17:27, Patrick Kelsey <kelsey at ieee.org> wrote:

> Hi,
>
> A bug was introduced in r254082 that results in BPF taps never being
> enabled for ieee80211 interfaces that are in monitor mode.
>
> Before r254082, bpf_track() in sys/net80211/ieee80211_freebsd.c was
> identifying ieee80211 interfaces by checking to see if the value of
> the ifp->if_start pointer was equal to ieee80211_start.  r254082 was a
> move away from using if_start to using if_transmit in the ieee80211
> stack, and bpf_track() was correspondingly updated to check the value
> of ifp->if_transmit against ieee80211_vap_transmit.  The problem is
> that ifp->if_transmit is set to null_transmit by
> ieee80211_vap_attach() in sys/net80211/ieee80211.c for interfaces that
> are in monitor mode (code that has been in place since r195846).
>
> One fix that resolves the issue is to use what is likely to be a more
> stable signature in the check in bpf_track().
>
> A patch against r256155 is attached.
>

Hi!

Good catch!

Yeah, this is all very dirty code that needs to be ripped out.

I'll get this committed ASAP.

Thanks!


-adrian