Return-path: Received: from mail-wi0-f180.google.com ([209.85.212.180]:33696 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752467AbbGBK2j convert rfc822-to-8bit (ORCPT ); Thu, 2 Jul 2015 06:28:39 -0400 Received: by wiwl6 with SMTP id l6so192139627wiw.0 for ; Thu, 02 Jul 2015 03:28:38 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1435826335.2285.6.camel@sipsolutions.net> References: <1435826335.2285.6.camel@sipsolutions.net> Date: Thu, 2 Jul 2015 12:28:38 +0200 Message-ID: (sfid-20150702_122844_436901_45CA62A9) Subject: Re: Association race when acting as AP? From: Michal Kazior To: Johannes Berg Cc: linux-wireless , "hostap@lists.shmoo.com" Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 2 July 2015 at 10:38, Johannes Berg wrote: > [please try to send w/o html if you're CC'ing the linux-wireless list] Ah, sorry. I suspect the "plain text mode" in gmail/www got disabled for some reason for that e-mail.. >> To me this looks like a race in hostapd. The station should be >> installed to driver _before_ sending Assoc Resp frame, not after. My >> quick-n-dirty hack seems to help: >> > [...] >> Is anyone aware of this problem already? Anyone working on it? Any >> gotchas I should be aware of before I go into fixing this in a proper >> way? Or am I missing something and this isn't actually a problem? > > The TI folks had a similar patch that broke open networks, not sure > what was wrong there. > > Ultimately, depending on the nl80211 capabilities, the station should > in fact be added (as unauthenticated) before even sending the > authentication response frame, and then stepping through the stages > appropriately. While I think it does make sense (I thought of this too, sounds desirable) I think it wouldn't solve the race problem entirely. The station might no longer be rejected with Deauth but may end up confusing AP's internal/offloaded STA powersave state depending on implementation detail (what do you do when you receive NullFunc from a station that you don't know assoc id of or isn't fully initialized as associated?). I.e. station should be transitioned to Assoc state before sending the Assoc Resp frame. > It should also react to errors by sending a negative association > response I guess. Good point. Michał