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Date:   Mon, 25 May 2020 12:58:14 +0200
From:   Stanislaw Gruszka <stf_xl@wp.pl>
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     Julian Calaby <julian.calaby@gmail.com>,
        Rui Salvaterra <rsalvaterra@gmail.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        Larry Finger <Larry.Finger@lwfinger.net>,
        linux-wireless@vger.kernel.org
Subject: Re: [RFC PATCH] rt2800lib: unconditionally enable MFP
Message-ID: <20200525105814.GA926693@wp.pl>
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On Mon, May 25, 2020 at 11:49:56AM +0200, Johannes Berg wrote:
> On Mon, 2020-05-25 at 11:31 +0200, Stanislaw Gruszka wrote:
> > On Mon, May 25, 2020 at 11:15:29AM +0200, Johannes Berg wrote:
> > > On Sun, 2020-05-24 at 14:39 +0200, Stanislaw Gruszka wrote:
> > > > > And once mac80211 is smart enough to make those decisions, couldn't we
> > > > > just enable MFP by default?
> > > 
> > > For the record, I don't think we'd really want to add such a thing to
> > > mac80211 ... easier done in the driver.
> > > 
> > > > If we will have indicator from mac80211 that MFP is configured, we can
> > > > just return -EOPNOTSUPP from rt2x00mac_set_key() for CCMP and that will
> > > > make MFP work without specifying nohwcrypt module parameter - software
> > > > encryption will be used anyway.
> > > 
> > > Not sure mac80211 really knows? Hmm.
> > 
> > After looking at this a bit more, seems we have indicator of MFP being
> > used in ieee80211_sta structure.
> 
> Yeah, where's my head ... sorry.
> 
> > So maybe adding check like below
> > will allow to remove nohwcrypt rt2x00 requirement for MFP ?
> 
> Seems reasonable, but will still do _everything_ in software for such
> connections. Still better than not connecting, I guess.

Yeah, and at least without nohwcrypt=y we can still use HW encryption
for non-MFP stations.

Rui, feel free to repost your patch with additional sta->mfp check.

If someone is willing to implement mt76 approach to have HW encryption offload
for MFP+CCMP, I'll be happy to review patch. From other hand, most people will
use MFP with modern ciphers anyway, so I'm not sure how much need is for such
patch.

Stanislaw