netdev - Re: PROBLEM: (DSA/Microchip): 802.1Q-Header lost on KSZ9477-DSA ingress without bridge

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: <CANn89iKxjxdiMdmFvz6hH-XaH4wNQiweo27cqh=W-gC7UT_OLA@mail.gmail.com>
Date:   Tue, 4 Aug 2020 13:36:56 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     "Gaube, Marvin (THSE-TL1)" <Marvin.Gaube@...at.de>,
        Florian Fainelli <f.fainelli@...il.com>,
        Woojung Huh <woojung.huh@...rochip.com>,
        Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: PROBLEM: (DSA/Microchip): 802.1Q-Header lost on KSZ9477-DSA
 ingress without bridge

On Tue, Aug 4, 2020 at 12:43 PM Vladimir Oltean <olteanv@...il.com> wrote:
>
> On Tue, Aug 04, 2020 at 12:40:24PM -0700, Eric Dumazet wrote:
> > On Tue, Aug 4, 2020 at 12:29 PM Vladimir Oltean <olteanv@...il.com> wrote:
> > >
> > > On Tue, Aug 04, 2020 at 07:54:18AM -0700, Eric Dumazet wrote:
> > > >
> > > > My 2013 commit was a bug fix, and hinted that in the future (eg in
> > > > net-next tree) the stop-the-bleed could be refined.
> > > >
> > > > +               /* Note: we might in the future use prio bits
> > > > +                * and set skb->priority like in vlan_do_receive()
> > > > +                * For the time being, just ignore Priority Code Point
> > > > +                */
> > > > +               skb->vlan_tci = 0;
> > > >
> > > > If you believe this can be done, this is great.
> > >
> > > Do you have a reproducer for that bug? I am willing to spend some time
> > > understand what is going on. This has nothing to do with priority. You
> > > vaguely described a problem with 802.1p (VLAN 0) and used that as an
> > > excuse to clear the entire vlan hwaccel tag regardless of VLAN ID. I'm
> > > curious because we also now have commit 36b2f61a42c2 ("net: handle
> > > 802.1P vlan 0 packets properly") in that general area, and I simply want
> > > to know if your patch still serves a valid purpose or not.
> > >
> >
> > I do not have a repro, the patch seemed to help at that time,
> > according to the reporter.
>
> Do you mind if I respectfully revert then? It's clear that the patch has
> loopholes already (it clears the vlan if it's hwaccel, but leaves it
> alone if it isn't) and that the proper solution should be different
> anyway.

Clearly the situation before the patch was not good, it seems well
explained in the changelog.

If you want to revert, you will need to convince the bug has been
solved in another way.

So it seems you might have to repro the initial problem.