Date:	Wed, 27 May 2015 02:00:36 +0000
From:	"Rose, Gregory V" <gregory.v.rose@...el.com>
To:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>,
	"Skidmore, Donald C" <donald.c.skidmore@...el.com>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	"intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>
CC:	"nhorman@...hat.com" <nhorman@...hat.com>,
	"jogreene@...hat.com" <jogreene@...hat.com>,
	Linux Netdev List <netdev@...r.kernel.org>,
	"Choi, Sy Jong" <sy.jong.choi@...el.com>,
	Rony Efraim <ronye@...lanox.com>,
	"David Miller" <davem@...emloft.net>,
	Edward Cree <ecree@...arflare.com>,
	Or Gerlitz <gerlitz.or@...il.com>,
	"sassmann@...hat.com" <sassmann@...hat.com>
Subject: RE: [PATCH v5 3/3] ixgbe: Add new ndo to trust VF


> -----Original Message-----
> From: Hiroshi Shimamoto [mailto:h-shimamoto@...jp.nec.com]
> Sent: Tuesday, May 26, 2015 5:28 PM
> To: Rose, Gregory V; Skidmore, Donald C; Kirsher, Jeffrey T; intel-wired-
> lan@...ts.osuosl.org
> Cc: nhorman@...hat.com; jogreene@...hat.com; Linux Netdev List; Choi, Sy
> Jong; Rony Efraim; David Miller; Edward Cree; Or Gerlitz;
> sassmann@...hat.com
> Subject: RE: [PATCH v5 3/3] ixgbe: Add new ndo to trust VF
> 
> > > -----Original Message-----
> > > From: Skidmore, Donald C
> > > Sent: Tuesday, May 26, 2015 10:46 AM
> > > To: Hiroshi Shimamoto; Rose, Gregory V; Kirsher, Jeffrey T;
> > > intel-wired- lan@...ts.osuosl.org
> > > Cc: nhorman@...hat.com; jogreene@...hat.com; Linux Netdev List;
> > > Choi, Sy Jong; Rony Efraim; David Miller; Edward Cree; Or Gerlitz;
> > > sassmann@...hat.com
> > > Subject: RE: [PATCH v5 3/3] ixgbe: Add new ndo to trust VF
> > >
> > >
> >
> > [snip]
> >
> > >
> > > > -----Original Message-----
> > > > From: Hiroshi Shimamoto [mailto:h-shimamoto@...jp.nec.com]
> > > > Sent: Monday, May 25, 2015 6:00 PM
> > > > To: Skidmore, Donald C; Rose, Gregory V; Kirsher, Jeffrey T;
> > > > intel-wired- lan@...ts.osuosl.org
> > > > Cc: nhorman@...hat.com; jogreene@...hat.com; Linux Netdev List;
> > > > Choi, Sy Jong; Rony Efraim; David Miller; Edward Cree; Or Gerlitz;
> > > > sassmann@...hat.com
> > > > Subject: RE: [PATCH v5 3/3] ixgbe: Add new ndo to trust VF
> > > >
> > > >
> > > > Do you mean that VF should care about it is trusted or not?
> > > > Should VF request MC Promisc again when it's trusted?
> > > > Or, do you mean VF never be trusted during its (or VM's) lifetime?
> > >
> > > I think the VF shouldn't directly know whether it is trusted or not
> >
> > That's completely irrevelant.  The person administering the PF will be
> > the person who provided trusted privileges to the VF.  He'll then
> > *tell* or somehow other communicate to the person administering the VF
> (probably himself/herself) and then proceed to execute commands on that VF
> that require trusted privileges.
> >
> > If the VF does not have trusted privileges then the commands to add
> > VLAN filters, set promiscuous modes, and any other privileged commands
> will fail.
> >
> > Let's not get too fancy with this.  It's simple - the host VMM admin
> > provides trusted privileges to the VF.  The person administering the
> > VF (if in fact it is not the same person, it usually will be) will
> proceed to do things that require VF trusted privileges.
> 
> Now I think that it's better to have an interface between PF and VF to
> know the VF is trusted.
> Otherwise VM cannot know whether its VF is trusted, that prevents
> automatic operations.

Agreed, it would be silly for the VF to have privileges but not know that it can use them!  

> Or add another communicating interface outside of ixgbe PF-VF mbox API?

We can't depend on any given vendor specific interface.  I'd add a very clear comment in the 
Physical Function ndo op that gives a VF trusted privileges that it is up to the driver to notify the VF driver.  But yes, in the case of Intel drivers the mailbox or admin queue (for i40e) would be the mechanism to do that.  I know you have some ixgbe patches that coincide with this patch so that's a good place to look.

> 
> >
> >
> > .  It
> > > should request MC Promisc and get it if it is trusted and not if it
> > > is not trusted.  So if you (as the system admin know you have a VF
> > > that will need to request MC Promisc make sure you promote that VF
> > > to trusted before assigning it to a VM.  That way when it requests
> > > MC Promisc the PF will be able to grant it.
> > >
> >
> > Multicast promiscuous should be allowed for the VFs.  We already allow
> > VFs to set whatever multicast filters they want so if they want to go
> > into MPE then so what?  We don't care.  It's not a security risk.
> > Right now, without any modification, the VF can set 30 multicast
> > filters and listen.  It can then remove those and set another 30 filters
> and listen.  And so on and so on.  So if a VF can already listen on any MC
> filter it wants then why this artificial restriction on MC promiscuous
> mode.
> 
> I'm fine with that, previously I mentioned about that.
> Without resetting PF, we can listen every MC packet which hash was set.
> PF reset will restore the last 30 MC addresses per VF.
> 
> Also there is a single hash entries table, all VFs will got a MC packet
> which hash was set in the table. If a VF user set a filter, other users
> will receive that MC packet.
> 
> >
> > We don't care about this case. Unicast promiscuous is the security risk
> and I think we've handled that.
> 
> So, should we separate the discussion, about trusting VF operation and
> about MC promiscuous?

Yes.  And to my mind it shouldn't really be in the context of virtual function privilege or trust.

> 
> >
> > >
> > > >
> > > > And what do you think about being untrusted from trusted state?
> > >
> > > This is an interesting question.  If we allowed a VM to go from
> > > trusted -> untrusted we would have to turn off any "special"
> > > configuration that trusted allowed.  Maybe in such cases we could
> > > reset the PF?  And of course require all the "special" configuration
> > > (MC Promisc) to default to off after being reset.
> > >
> >
> > To remove privileges from a VF that you're already set to privileged
> > will require destruction of the VF VSI and VFLR to the VF - after it
> comes up it can't do any further privileged operations.
> 
> yeah, sounds good to reset VF on changing privilege.
> 
> >
> > [snip
> >
> > > This too is a valid point.  Currently we would just not do it (MC
> > > Promisc) and the VF would have to figure that out for itself.
> > > Passing a NAK back to the VF might be nicer. :)  Of course I assumed
> > > the sysadm would know that he/she wanted to give a VF trusted status
> > > and would do that before the VF was even assigned to a VM, so the
> > > issue would never come up.  Maybe that is not valid for your use case?
> >
> > Let's not worry about MC promiscuous mode.  As I pointed out above we
> > already let VFs set any MC address filters they want so that horse has
> already left the barn.
> 
> Do you think that VF MC promiscuous mode isn't needed to handle under
> trusted mode, right?

Correct, that's my opinion on it given the fact that historically there has never been any restriction on setting MC addresses by the VF. See my comments above in the respect.

Thanks and regards Hiroshi,

- Greg

> 
> thanks,
> Hiroshi
> 
> >
> > Focus on getting the VF privileged mode configuration going and then
> > we're well on our way to accomplishing what we need to do.
> >
> > - Greg

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