[PATCH] DPP: respond to GAS on the same channel it was received on

[Jouni Malinen]

On Wed, Mar 03, 2021 at 09:53:33AM +0000, Michal Kazior wrote:
> When I was testing dpp_auth_init on an AP with
> Enrollee on a different channel from the AP I was
> getting failures. This happened on hwsim in UML
> with time-travel for me. I don't recall seeing
> this with real devices, presumably because of lax
> offchan implementation.

Is this with a hwsim test case that already exists in hostap.git? Does
it fail every time in your test setup?

> The AP reported the following logs (grepped):
> 
> > 1614762426.860212: RX_ACTION category 4 action 10 sa 02:00:00:00:01:00 da 02:00:00:00:00:00 len 227 freq 2412
> > 1614762426.860212: wlan0: GAS: GAS Initial Request from 02:00:00:00:01:00 (dialog token 239)
> > 1614762426.860233: DPP: Wait for Configuration Result
> > 1614762426.860234: nl80211: Send Action frame (ifindex=5, freq=2462 MHz wait=0 ms no_cck=0 offchanok=0)
> > 1614762428.861186: DPP: Timeout while waiting for Configuration Result
> > 1614762428.861186: wlan0: DPP-CONF-FAILED

Can you please share the full debug log for this? I'd like to understand
what exactly happened with the channel negotiation here.

> I'm not sure if this is the right thing to do. And
> there seems to be more cases where APs freq is
> used instead of the GAS req freq that could
> potentially be updated. There's at least the GAS
> comeback case I don't handle here. This as-is does
> help with my hwsim test though.
> 
> On one hand it seems perhaps the Enrollee should
> try to do GAS on the APs channel. But is it well
> equiped/informed to do so? I'm not familiar with
> the spec that much.

DPP configuration exchange (GAS) is supposed to happen on the same
channel on which the last frame of DPP authentication exchange happened.

-- 
Jouni Malinen                                            PGP id EFC895FA