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

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Date:	Fri, 6 Mar 2015 09:46:41 +0000
From:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
To:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
CC:	"e1000-devel@...ts.sourceforge.net" 
	<e1000-devel@...ts.sourceforge.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"Choi, Sy Jong" <sy.jong.choi@...el.com>,
	Hayato Momma <h-momma@...jp.nec.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"ben@...adent.org.uk" <ben@...adent.org.uk>
Subject: RE: [PATCH v2] ixgbe: make VLAN filter conditional

> On Fri, 2015-03-06 at 06:04 +0000, Hiroshi Shimamoto wrote:
> > > From: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
> > >
> > > 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