Re: [PATCH wpan-next 0/2] ieee802154: Beaconing support

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Alexander Aring <aahringo@redhat.com>
Cc: Michael Richardson <mcr@sandelman.ca>,
	Alexander Aring <alex.aring@gmail.com>,
	Stefan Schmidt <stefan@datenfreihafen.org>,
	linux-wpan@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Eric Dumazet <edumazet@google.com>,
	netdev@vger.kernel.org, David Girault <david.girault@qorvo.com>,
	Romuald Despres <romuald.despres@qorvo.com>,
	Frederic Blain <frederic.blain@qorvo.com>,
	Nicolas Schodet <nico@ni.fr.eu.org>,
	Guilhem Imberton <guilhem.imberton@qorvo.com>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Subject: Re: [PATCH wpan-next 0/2] ieee802154: Beaconing support
Date: Mon, 30 Jan 2023 10:50:51 +0100	[thread overview]
Message-ID: <20230130105051.24926c5f@xps-13> (raw)
In-Reply-To: <CAK-6q+ix3PybA-Af-QRRZ2BwSLYH76SnqhRCsmRpiy_6PFrorw@mail.gmail.com>

Hello,

aahringo@redhat.com wrote on Fri, 27 Jan 2023 20:57:08 -0500:

> Hi,
> 
> On Fri, Jan 27, 2023 at 2:52 PM Michael Richardson <mcr@sandelman.ca> wrote:
> >
> >
> > Alexander Aring <aahringo@redhat.com> wrote:  
> >     >> - MLME ops without feedback constraints like beacons -> should go
> >     >> through the hot path, but not through the whole net stack, so
> >     >> ieee802154_subif_start_xmit()
> >     >>  
> >  
> >     > it will bypass the qdisc handling (+ some other things which are around
> >     > there). The current difference is what I see llsec handling and other
> >     > things which might be around there?

Not exactly, because llsec handling is not done in the net/ stack, but
right inside the ieee802154 transmit callbacks, so I'd say it will be
quite easy to tweak when we have a clear view of what we want in terms
of encryption/integrity checking/signatures.

> >     > It depends if other "MLME-ops" need
> >     > to be e.g. encrypted or not.  
> >
> > I haven't followed the whole thread.
> > So I am neither agreeing nor disagreeing, just clarifying.
> > Useful beacons are "signed" (have integrity applied), but not encrypted.
> >  
> 
> I see. But that means they need to be going through llsec, just the
> payload isn't encrypted and the MIC is appended to provide integrity.
> 
> > It's important for userspace to be able to receive them, even if we don't
> > have a key that can verify them.  AFAIK, we have no specific interface to
> > receive beacons.
> >  
> 
> This can be done over multiple ways. Either over a socket
> communication or if they appear rarely we can put them into a netlink
> event. In my opinion we already put that in a higher level API in
> passive scan to interpret the receiving of a beacon on kernel level
> and trigger netlink events.

Indeed.

> I am not sure how HardMAC transceivers handle them on the transceiver
> side only or if they ever provide them to the next layer or not?
> For SoftMAC you can actually create a AF_PACKET raw socket, and you
> should see everything which bypass hardware address filters and kernel
> filters. Then an application can listen to them.

Thanks,
Miquèl