netdev - Re: [PATCH net-next v9 3/4] virtio_net: Extend virtio to use VF datapath when available

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: <20180502184326-mutt-send-email-mst@kernel.org>
Date:   Wed, 2 May 2018 18:47:27 +0300
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     "Samudrala, Sridhar" <sridhar.samudrala@...el.com>,
        stephen@...workplumber.org, davem@...emloft.net,
        netdev@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        virtio-dev@...ts.oasis-open.org, jesse.brandeburg@...el.com,
        alexander.h.duyck@...el.com, kubakici@...pl, jasowang@...hat.com,
        loseweigh@...il.com, aaron.f.brown@...el.com
Subject: Re: [PATCH net-next v9 3/4] virtio_net: Extend virtio to use VF
 datapath when available

On Wed, May 02, 2018 at 09:50:21AM +0200, Jiri Pirko wrote:
> Wed, May 02, 2018 at 02:20:26AM CEST, sridhar.samudrala@...el.com wrote:
> >On 4/30/2018 12:20 AM, Jiri Pirko wrote:
> >> 
> >> > > Now I try to change mac of the failover master:
> >> > > [root@...t1 ~]# ip link set ens3 addr 52:54:00:b2:a7:f3
> >> > > RTNETLINK answers: Operation not supported
> >> > > 
> >> > > That I did expect to work. I would expect this would change the mac of
> >> > > the master and both standby and primary slaves.
> >> > If a VF is untrusted, a VM will not able to change its MAC and moreover
> >> Note that at this point, I have no VF. So I'm not sure why you mention
> >> that.
> >> 
> >> 
> >> > in this mode we are assuming that the hypervisor has assigned the MAC and
> >> > guest is not expected to change the MAC.
> >> Wait, for ordinary old-fashioned virtio_net, as a VM user, I can change
> >> mac and all works fine. How is this different? Change mac on "failover
> >> instance" should work and should propagate the mac down to its slaves.
> >> 
> >> 
> >> > For the initial implementation, i would propose not allowing the guest to
> >> > change the MAC of failover or standby dev.
> >> I see no reason for such restriction.
> >> 
> >
> >It is true that a VM user can change mac address of a normal virtio-net interface,
> >however when it is in STANDBY mode i think we should not allow this change specifically
> >because we are creating a failover instance based on a MAC that is assigned by the
> >hypervisor.
> >
> >Moreover,  in a cloud environment i would think that PF/hypervisor assigns a MAC to
> >the VF and it cannot be changed by the guest.
> 
> So that is easy. You allow the change of the mac and in the "failover"
> mac change implementation you propagate the change down to slaves. If
> one slave does not support the change, you bail out. And since VF does

I wish people would say primary/standby and not "VF" :)

> not allow it as you say, once it will be enslaved, the mac change could
> not be done. Seems like a correct behavior to me


what if primary does not allow mac changes and is attached after
mac is changed on standy?


> and is in-sync with how
> bond/team behaves.

I think in the end virtio can just block MAC changes for simplicity.

I personally don't see softmac as a must have feature in v1,
we can add it later.

What's the situation with init scripts and whether it's
possible to make them work well would be a better question.

> 
> >
> >So for the initial implementation, do you see any issues with having this restriction
> >in STANDBY mode.
> >
> >