git: 68a46f11eada - main - e1000: Restore VF interface random MAC

[Shawn Webb]

Could ether_gen_addr be updated to take into account the zero'd
hostuuid and handle appropriately like you mentioned below? 

On Thu, Apr 15, 2021 at 03:12:14PM -0500, Kyle Evans wrote:
> I think it'd be the right choice, but it needs a little work first.
> e.g., it's not a good fit right now for VMs that don't use loader, for
> instance, because it relies on the hostuuid actually being somewhat
> unique or else it generates the same MAC address across different VMs
> and you end up with conflicts in the broadcast domain. I think there's
> a good argument to make for having it check if the hostuuid is the
> default all-0 hostuuid and just generating a random address as this
> does right now. I might go ahead and prepare such a change and
> document the KPI in the process.
> 
> On Thu, Apr 15, 2021 at 3:06 PM Kevin Bowling <kevin.bowling at kev009.com> wrote:
> >
> > I would like to discuss this further, it crossed my mind, but none of
> > the intel drivers currently use it.  If this is the right KPI I think
> > a review should be prepared that updates e1000, ixgbe (ixv), ixl
> > (iavf) in one go.
> >
> > Regards,
> > Kevin
> >
> > On Thu, Apr 15, 2021 at 12:36 PM Kyle Evans <kevans at freebsd.org> wrote:
> > >
> > > On Thu, Apr 15, 2021 at 2:32 PM Ronald Klop <ronald-lists at klop.ws> wrote:
> > > >
> > > > On 4/15/21 8:48 PM, Kevin Bowling wrote:
> > > > > The branch main has been updated by kbowling (ports committer):
> > > > >
> > > > > URL: https://cgit.FreeBSD.org/src/commit/?id=68a46f11eadab48a1da9e3d3900569a6a1ce142e
> > > > >
> > > > > commit 68a46f11eadab48a1da9e3d3900569a6a1ce142e
> > > > > Author:     Kevin Bowling <kbowling at FreeBSD.org>
> > > > > AuthorDate: 2021-04-15 18:45:02 +0000
> > > > > Commit:     Kevin Bowling <kbowling at FreeBSD.org>
> > > > > CommitDate: 2021-04-15 18:45:02 +0000
> > > > >
> > > > >      e1000: Restore VF interface random MAC
> > > > >
> > > > >      Restore 525e07418c77 after the iflib conversion of igb(4). This
> > > > >      reenables random MAC address generation when attaching to a VF with a
> > > > >      zeroed MAC.
> > > > >
> > > > >      PR:             253535
> > > > >      Reported by:    Balaev PA <mail at void.so>
> > > > >      Reviewed by:    markj
> > > > >      MFC after:      2 weeks
> > > > >      Differential Revision:  https://reviews.freebsd.org/D29785
> > > > > ---
> > > > >   sys/dev/e1000/if_em.c | 21 ++++++++++++++++++---
> > > > >   1 file changed, 18 insertions(+), 3 deletions(-)
> > > > >
> > > > > diff --git a/sys/dev/e1000/if_em.c b/sys/dev/e1000/if_em.c
> > > > > index 6f022c80c01c..79a617b3342f 100644
> > > > > --- a/sys/dev/e1000/if_em.c
> > > > > +++ b/sys/dev/e1000/if_em.c
> > > > > @@ -1061,9 +1061,17 @@ em_if_attach_pre(if_ctx_t ctx)
> > > > >       }
> > > > >
> > > > >       if (!em_is_valid_ether_addr(hw->mac.addr)) {
> > > > > -             device_printf(dev, "Invalid MAC address\n");
> > > > > -             error = EIO;
> > > > > -             goto err_late;
> > > > > +             if (adapter->vf_ifp) {
> > > > > +                     u8 addr[ETHER_ADDR_LEN];
> > > > > +                     arc4rand(&addr, sizeof(addr), 0);
> > > > > +                     addr[0] &= 0xFE;
> > > > > +                     addr[0] |= 0x02;
> > > > > +                     bcopy(addr, hw->mac.addr, sizeof(addr));
> > > > > +             } else {
> > > > > +                     device_printf(dev, "Invalid MAC address\n");
> > > > > +                     error = EIO;
> > > > > +                     goto err_late;
> > > > > +             }
> > > >
> > > >
> > > > Just curious. Would ether_gen_addr() be useful here?
> > > > It is implemented in net/if_ethersubr.c.
> > > >
> > >
> > > I had asked myself the same question, but I suspect these machines may
> > > not necessarily have a hostuuid preloaded to avoid collisions from the
> > > generated addresses.
> > >
> > > Thanks,
> > >
> > > Kyle Evans
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-- 
Shawn Webb
Cofounder / Security Engineer
HardenedBSD

https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/raw/master/Shawn_Webb/03A4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc
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