Received-SPF: pass (google.com: best guess record for domain of linux-wireless-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH 04/11] wil6210: fix PTK re-key race
To:     Alexander Wetzel <alexander@wetzel-home.de>,
        Arend Van Spriel <arend.vanspriel@broadcom.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        Maya Erez <merez@codeaurora.org>
Cc:     Ahmad Masri <amasri@codeaurora.org>,
        linux-wireless@vger.kernel.org, wil6210@qti.qualcomm.com
References: <1567931575-27984-5-git-send-email-merez@codeaurora.org>
 <20190910132315.D7AC7602F2@smtp.codeaurora.org>
 <7b636313-fa4a-5ee4-935a-ba2ed5dde1e5@wetzel-home.de>
 <2c6bc637-62c2-020c-ab83-d2e1677d96b2@gmail.com>
 <5716f475-856e-7fd2-637b-67927f4f78bc@wetzel-home.de>
 <74c0e328-320c-0999-836e-1bfb0fa224ff@broadcom.com>
 <13f699ef-16c2-3ba7-79a0-0934f5e39368@gmail.com>
 <46f1141c-929c-9686-017d-fe4305d9c922@wetzel-home.de>
From:   Denis Kenzior <denkenz@gmail.com>
Message-ID: <31dd258c-7ff5-005b-9dee-b4753e3e5250@gmail.com>
Date:   Tue, 17 Sep 2019 10:32:08 -0500
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <46f1141c-929c-9686-017d-fe4305d9c922@wetzel-home.de>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

Hi Alexander,

> And that the intend of it is to replace the "old" path.
Correct.

> 
> So the best way forward here would be to
> 
> 1) implement the patch here to work around the problem without 
> control_port or the theoretical QDISC bypass
> 2) start implementing control port for the future.
> 
> correct?
> 

I don't know what the right answer is, but it seems strange to me that 
we developed a 'better way', upstreamed it several years ago, but are 
still trying to kludge around adding special flags to what is now 
considered a legacy approach.  Also disconcerting that not a single 
fullmac driver has added support for this 'better way' yet.

> 
>> CONTROL_PORT was added specifically to take care of the re-keying 
>> races and can be extended with additional attributes over time, as 
>> needed (perhaps for extended key id, etc).  Also note that in our 
>> testing CONTROL_PORT is _way_ faster than PAE socket...
>>
> 
> Extended Key ID is pretty robust when rekeying and the driver/card only 
> has to take care to not mix KeyIDs within one A-MPDU. It's no problem 
> encrypting eapol#4 with the new key. You can even encrypt it at the 
> initial connect and it will work. Basically all races the "classical" 
> rekey has to work around go away.
> 
> For "normal" rekeys it's working pretty well with ath9k and iwlwifi even 
> without control_port and just learned some weeks ago that QDISC could 
> still cause issues...

Okay, if control port doesn't need to handle extended keys then even better.

By the way, thanks for your earlier explanation (upthread).

Regards,
-Denis