Re: [PATCH v5 net-next 6/6] selftests: forwarding: add test of MAC-Auth Bypass to locked port tests

[netdev]

On 2022-09-12 11:08, Ido Schimmel wrote:
> On Sun, Sep 11, 2022 at 11:23:55AM +0200, netdev@xxxxxxxxxxxxxxxxxxxx 
> wrote:
> > On 2022-09-11 02:13, Vladimir Oltean wrote:
> > > On Fri, Sep 09, 2022 at 03:11:56PM +0200, netdev@xxxxxxxxxxxxxxxxxxxx
> > > wrote:
> > > > > > > On Wed, Sep 07, 2022 at 11:10:07PM +0200, netdev@xxxxxxxxxxxxxxxxxxxx wrote:
> > > > > > > > I am at the blackhole driver implementation now, as I suppose that the
> > > > > > > > iproute2 command should work with the mv88e6xxx driver when adding blackhole
> > > > > > > > entries (with a added selftest)?
> > > > > > > > I decided to add the blackhole feature as new ops for drivers with functions
> > > > > > > > blackhole_fdb_add() and blackhole_fdb_del(). Do you agree with that approach?
> > > > > > >
> > > > > > > I assume you are talking about extending 'dsa_switch_ops'?
> > > > > >
> > > > > > Yes, that is the idea.
> > > > > >
> > > > > > > If so, it's up to the DSA maintainers to decide.
> > > > >
> > > > > What will be the usefulness of adding a blackhole FDB entry from user
> > > > > space?
> > > >
> > > > With the software bridge it could be used to signal a untrusted host
> > > > in
> > > > connection with a locked port entry attempt. I don't see so much use
> > > > other
> > > > that test purposes with the driver though.
> > >
> > > Not a huge selling point, to be honest. Can't the blackhole flag remain
> > > settable only in the device -> bridge direction, with user space just
> > > reading it?
> >
> > That is possible, but it would of course not make sense to have 
> > selftests of
> > the feature as that would not work unless there is a driver with this
> > capability (now just mv88e6xxx).
>
> The new "blackhole" flag requires changes in the bridge driver and
> without allowing user space to add such entries, the only way to test
> these changes is with mv88e6xxx which many of us do not have...

I am now building from new system (comp), and the kernel selftests are 
not being installed correctly, so I haven't been able to run the 
selftests yet.

I have made a blackhole selftest, which looks like this:

test_blackhole_fdb()
{
        RET=0

        check_blackhole_fdb_support || return 0

        tcpdump_start $h2
        $MZ $h1 -q -t udp -a $h1 -b $h2
        tcpdump_stop
        tcpdump_show | grep -q udp
        check_err $? "test_blackhole_fdb: No packet seen on initial"
        tcpdump_cleanup

        bridge fdb add `mac_get $h2` dev br0 blackhole
        bridge fdb show dev br0 | grep -q "blackhole"
        check_err $? "test_blackhole_fdb: No blackhole FDB entry found"

        tcpdump_start $h2
        $MZ $h1 -q -t udp -a $h1 -b $h2
        tcpdump_stop
        tcpdump_show | grep -q udp
        check_fail $? "test_blackhole_fdb: packet seen with blackhole 
fdb entry"
        tcpdump_cleanup

        bridge fdb del `mac_get $h2` dev br0 blackhole
        bridge fdb show dev br0 | grep -q "blackhole"
        check_fail $? "test_blackhole_fdb: Blackhole FDB entry not 
deleted"

        tcpdump_start $h2
        $MZ $h1 -q -t udp -a $h1 -b $h2
        tcpdump_stop
        tcpdump_show | grep -q udp
        check_err $? "test_blackhole_fdb: No packet seen after removing 
blackhole FDB entry"
        tcpdump_cleanup

        log_test "Blackhole FDB entry test"
}

the setup is simple and is the same as in bridge_sticky_fdb.sh.

Does the test look sound or is there obvious mistakes?