Re: [PATCH 3/3] OWE: allow adding new STAs w/o DH IEs when OWE is offloaded

On Thu, Feb 13, 2020 at 08:51:24AM +0000, Sergey Matyukevich wrote:
> Drivers/cards supporting SME internally may perform OWE offloading to
> hostapd. This can be done using EVENT_UPDATE_DH mechanism and appropriate
> handler hostapd_notif_update_dh_ie. When this mechanism is in use, then
> hostapd creates STA entries for OWE processing and reports DH information
> element to driver. After association is completed, driver notifies hostapd
> that new STA is ready using EVENT_ASSOC mechanism and appropriate handler
> hostapd_notif_assoc.
> 
> Currently the availability of DH IEs is validated in both events by the
> function wpa_validate_wpa_ie. However for EVENT_ASSOC this is needed only
> for non-SME drivers. For SME drivers this may be redundant since during
> processing of OWE offload STA entry has been already added and OWE PMK
> has been already created.
> 
> This patch modifies OWE processing so that drivers performing OWE offload
> may not pass DH IE in EVENT_ASSOC. For this purpose the following changes
> have been introduced. Function wpa_validate_wpa_ie is modified so that it
> does not report failure if DH IE is not provided. DH IE availability is
> checked in owe_assoc_req_process in the case if previously derived
> OWE PMK is not available. Besides, availability of DH IE is verified
> in handle_assoc(check_assoc_ies).

Why would a driver not pass Diffied-Hellman Parameter element in
EVENT_ASSOC? data->assoc_info.req_ies is supposed to include _all_ IEs
received in the (Re)Association Request frame. I would not want to make
an exception on that if that results in drivers hiding IEs that were
included in that frame.

-- 
Jouni Malinen                                            PGP id EFC895FA