netdev - Re: [PATCH net] net: bridge: switchdev: don't notify FDB entries with "master dynamic"

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: <ZDbVgqV9JT7Ru96j@shredder>
Date:   Wed, 12 Apr 2023 19:00:02 +0300
From:   Ido Schimmel <idosch@...dia.com>
To:     Vladimir Oltean <vladimir.oltean@....com>
Cc:     netdev@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        "Hans J. Schultz" <netdev@...io-technology.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Ivan Vecera <ivecera@...hat.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Arkadi Sharshevsky <arkadis@...lanox.com>,
        Ido Schimmel <idosch@...lanox.com>,
        bridge@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net: bridge: switchdev: don't notify FDB entries
 with "master dynamic"

On Wed, Apr 12, 2023 at 05:27:33PM +0300, Vladimir Oltean wrote:
> How are extern_learn FDB entries processed by spectrum's
> SWITCHDEV_FDB_ADD_TO_DEVICE handler?

No different than "BR_FDB_STATIC", which is a bug I'm aware of and
intend to fix in net-next when I get the time (together with all the
other combinations enabled by the bridge). Entry has ageing disabled,
but can roam in which case it becomes age-able.

TBH, I think most devices don't handle "BR_FDB_STATIC" correctly. In the
Linux bridge, "BR_FDB_STATIC" only means ageing disabled. The entry can
still roam, but remains "static". I believe that in most devices out
there "static" means no roaming and no ageing which is equivalent to
"BR_FDB_STATIC | BR_FDB_STICKY". Mentioned in your commit message as
well: "As for the hardware FDB entry, that's static, it doesn't move
when the station roams."

As it stands, the situation is far from perfect, but the patch doesn't
solve a regression (always broken) and will introduce one. My suggestion
allows you to move forward and solve the "dynamic" case, so let's
proceed with that unless there's a better alternative.