RE: [PATCH v2] ixgbe: make VLAN filter conditional

[Hiroshi Shimamoto]

> On Fri, 2015-03-06 at 06:04 +0000, Hiroshi Shimamoto wrote:
> > > From: Hiroshi Shimamoto <h-shimamoto@xxxxxxxxxxxxx>
> > >
> > > Disable hardware VLAN filtering if netdev->features VLAN flag is
> > dropped.
> > >
> > > In SR-IOV case, there is a use case which needs to disable VLAN
> > filter.
> > > For example, we need to make a network function with VF in
> > virtualized
> > > environment. That network function may be a software switch, a
> > router
> > > or etc. It means that that network function will be an end point
> > which
> > > terminates many VLANs.
> > >
> > > In the current implementation, VLAN filtering always be turned on
> > and
> > > VF can receive only 63 VLANs. It means that only 63 VLANs can be
> > terminated
> > > in one NIC.
> > >
> > > With this patch, if the user turns VLAN filtering off on the host,
> > VF
> > > can receive every VLAN packet.
> > >
> > > This VLAN filtering can be turned on or off when SR-IOV is disabled,
> > if not
> > > the operation is rejected.
> >
> > Hi,
> >
> > any comment about this?
> > I added a warning message and prevent operation during SR-IOV is
> > enabled.
> 
> Yes, the warning message you added says nothing of the huge security
> hole this exposes.  We need a message the correctly expresses the
> dangers in turning this off.

hm okay.
Do you mean I should add a message like "this causes SECURITY issue", right?

> 
> Also it does not appear that you addressed Ben Hutchings concerns, as I
> asked.  Correct me if I am wrong and you did address Ben's concerns.

I think Ben's suggestion is to prevent turn VLAN filtering back on during
VFs are used because that breaks guest's behavior.
I added the code that make it impossible. We cannot turn on (or off) if
the NIC has VFs.

thanks,
Hiroshi