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

Jouni Malinen j at w1.fi
Sat Mar 6 10:03:45 GMT 2021

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

More information about the Hostap mailing list