linux-kernel - Re: [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB implementation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <86r16u6o46.fsf@gmail.com>
Date:   Tue, 22 Mar 2022 15:47:05 +0100
From:   Hans Schultz <schultz.hans@...il.com>
To:     Hans Schultz <schultz.hans@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Hans Schultz <schultz.hans@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>, davem@...emloft.net, kuba@...nel.org,
        netdev@...r.kernel.org, Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Ivan Vecera <ivecera@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Ido Schimmel <idosch@...dia.com>, linux-kernel@...r.kernel.org,
        bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net-next 3/3] net: dsa: mv88e6xxx: mac-auth/MAB
 implementation

On tis, mar 22, 2022 at 14:21, Hans Schultz <schultz.hans@...il.com> wrote:
> On tis, mar 22, 2022 at 13:08, Vladimir Oltean <olteanv@...il.com> wrote:
>> On Tue, Mar 22, 2022 at 12:01:13PM +0100, Hans Schultz wrote:
>>> On fre, mar 18, 2022 at 15:19, Vladimir Oltean <olteanv@...il.com> wrote:
>>> > On Fri, Mar 18, 2022 at 02:10:26PM +0100, Hans Schultz wrote:
>>> >> In the offloaded case there is no difference between static and dynamic
>>> >> flags, which I see as a general issue. (The resulting ATU entry is static
>>> >> in either case.)
>>> >
>>> > It _is_ a problem. We had the same problem with the is_local bit.
>>> > Independently of this series, you can add the dynamic bit to struct
>>> > switchdev_notifier_fdb_info and make drivers reject it.
>>> >
>>> >> These FDB entries are removed when link goes down (soft or hard). The
>>> >> zero DPV entries that the new code introduces age out after 5 minutes,
>>> >> while the locked flagged FDB entries are removed by link down (thus the
>>> >> FDB and the ATU are not in sync in this case).
>>> >
>>> > Ok, so don't let them disappear from hardware, refresh them from the
>>> > driver, since user space and the bridge driver expect that they are
>>> > still there.
>>> 
>>> I have now tested with two extra unmanaged switches (each connected to a
>>> seperate port on our managed switch, and when migrating from one port to
>>> another, there is member violations, but as the initial entry ages out,
>>> a new miss violation occurs and the new port adds the locked entry. In
>>> this case I only see one locked entry, either on the initial port or
>>> later on the port the host migrated to (via switch).
>>> 
>>> If I refresh the ATU entries indefinitly, then this migration will for
>>> sure not work, and with the member violation suppressed, it will be
>>> silent about it.
>>
>> Manual says that migrations should trigger miss violations if configured
>> adequately, is this not the case?
>>
> Yes, but that depends on the ATU entries ageing out. As it is now, it works.
>
>>> So I don't think it is a good idea to refresh the ATU entries
>>> indefinitely.
>>> 
>>> Another issue I see, is that there is a deadlock or similar issue when
>>> receiving violations and running 'bridge fdb show' (it seemed that
>>> member violations also caused this, but not sure yet...), as the unit
>>> freezes, not to return...

I have now verified that it is only on miss violations that the problem
occurs, so it seems that there is a deadlock (with 'bridge fdb show')
somehow with the nl lock that the handling of ATU miss violations
acquires.

>>
>> Have you enabled lockdep, debug atomic sleep, detect hung tasks, things
>> like that?
>
> No, I haven't looked deeper into it yet. Maybe I was hoping someone had
> an idea... but I guess it cannot be a netlink deadlock?