Linux Ethernet Bridging - Oct 2022 - [Bridge] [PATCH v8 net-next 10/12] net: dsa: mv88e6xxx: mac-auth/MAB implementation

On Fri, Oct 21, 2022 at 07:18:59PM +0200, netdev at kapio-technology.com
wrote:
> On 2022-10-21 18:30, Vladimir Oltean wrote:
> > On Fri, Oct 21, 2022 at 03:16:21PM +0200, netdev at
kapio-technology.com wrote:
> > > As it is now in the bridge, the locked port part is handled
before learning
> > > in the ingress data path, so with BR_LEARNING and BR_PORT_LOCKED,
I think it
> > > will work as it does now except link local packages.
> > 
> > If link-local learning is enabled on a locked port, I think those
> > addresses should also be learned with the BR_FDB_LOCKED flag. The
> > creation of those locked FDB entries can be further suppressed by the
> > BROPT_NO_LL_LEARN flag.
> > 
> > > If your suggestion of BR_LEARNING causing BR_FDB_LOCKED on a
locked port, I
> > > guess it would be implemented under br_fdb_update() and
BR_LEARNING +
> > > BR_PORT_LOCKED would go together, forcing BR_LEARNING in this
case, thus also
> > > for all drivers?
> > 
> > Yes, basically where this is placed right now (in
br_handle_frame_finish):
> 
> As I don't know what implications it would have for other drivers to
have learning
> forced enabled on locked ports, I cannot say if it is a good idea or not.
> Right now learning is not forced either way as is, but the consensus is
that learning
> should be off with locked ports, which it would be either way in the common
case I
> think.
I don't think I fully understand what you mean by forcing BR_LEARNING.
A bridge port gets created with a default set of flags as can be seen in
new_nbp().
Those flags include BR_LEARNING but don't include BR_PORT_LOCKED.

The user can decide he wants to make the port use 802.1X without MAB, so
he enables BR_PORT_LOCKED and disables BR_LEARNING, all with the same
netlink command (ip link set swp0 type bridge_slave learning off locked on).

How was the driver forced into anything?

On 2022-10-21 19:30, Vladimir Oltean wrote:
> On Fri, Oct 21, 2022 at 07:18:59PM +0200, netdev at kapio-technology.com 
> wrote:
>> On 2022-10-21 18:30, Vladimir Oltean wrote:
>> > On Fri, Oct 21, 2022 at 03:16:21PM +0200, netdev at
kapio-technology.com wrote:
>> > > As it is now in the bridge, the locked port part is handled
before learning
>> > > in the ingress data path, so with BR_LEARNING and
BR_PORT_LOCKED, I think it
>> > > will work as it does now except link local packages.
>> >
>> > If link-local learning is enabled on a locked port, I think those
>> > addresses should also be learned with the BR_FDB_LOCKED flag. The
>> > creation of those locked FDB entries can be further suppressed by
the
>> > BROPT_NO_LL_LEARN flag.
>> >
>> > > If your suggestion of BR_LEARNING causing BR_FDB_LOCKED on a
locked port, I
>> > > guess it would be implemented under br_fdb_update() and
BR_LEARNING +
>> > > BR_PORT_LOCKED would go together, forcing BR_LEARNING in this
case, thus also
>> > > for all drivers?
>> >
>> > Yes, basically where this is placed right now (in
br_handle_frame_finish):
>> 
>> As I don't know what implications it would have for other drivers
to
>> have learning
>> forced enabled on locked ports, I cannot say if it is a good idea or 
>> not.
>> Right now learning is not forced either way as is, but the consensus 
>> is that learning
>> should be off with locked ports, which it would be either way in the 
>> common case I
>> think.
> 
> I don't think I fully understand what you mean by forcing BR_LEARNING.
> A bridge port gets created with a default set of flags as can be seen
> in new_nbp().
> Those flags include BR_LEARNING but don't include BR_PORT_LOCKED.
> 
> The user can decide he wants to make the port use 802.1X without MAB, 
> so
> he enables BR_PORT_LOCKED and disables BR_LEARNING, all with the same
> netlink command (ip link set swp0 type bridge_slave learning off locked 
> on).
> 
> How was the driver forced into anything?
Well, with this change, to have MAB working, the bridge would need 
learning on
of course, but how things work with the bridge according to the flags, 
they
should also work in the offloaded case if you ask me. There should be no
difference between the two, thus MAB in drivers would have to be with
learning on.