[Openib-windows] RE: [openib-general] mthca FMR correctness (andmemory windows)

[Doug O'Neil]

Disregard, wrong list.

- Doug

> -----Original Message-----
> From: openib-windows-bounces at openib.org [mailto:openib-windows-
> bounces at openib.org] On Behalf Of Doug O'Neil
> Sent: Monday, March 20, 2006 5:22 PM
> To: Talpey, Thomas
> Cc: openib-windows at openib.org
> Subject: [Openib-windows] RE: [openib-general] mthca FMR correctness
> (andmemory windows)
> 
> 
> 
> > -----Original Message-----
> > From: openib-general-bounces at openib.org [mailto:openib-general-
> > bounces at openib.org] On Behalf Of Talpey, Thomas
> > Sent: Monday, March 20, 2006 5:00 PM
> > To: Roland Dreier
> > Cc: openib-general at openib.org
> > Subject: Re: [openib-general] mthca FMR correctness (and memory
> windows)
> >
> > At 07:50 PM 3/20/2006, Roland Dreier wrote:
> > >    Thomas> Yes, I know about binding on a separate queue. That
> > >    Thomas> doesn't work, because windows are semantically not
> > >    Thomas> fungible (for security reasons).
> > >
> > >Can you elaborate on the issue of fungibility?  If one entity has
two
> > >QPs, one of which it's using for traffic and one of which it's
using
> > >for MW binds, I don't see any security issue (beyond the fact that
> > >you've now given up ordering of operations between the QPs).
> >
> > If I can snoop or guess rkeys (not a huge challenge with 32 bits),
and
> > if I can use them on an arbitrary queuepair, then I can handily peek
> and
> > poke at memory that does not belong to me.
> >
> > For this reason, iWARP requires its steering tags to be scoped to a
> single
> > connection.
> 
> >From iWarp RDMA Verbs Section 5.2
> 
>   "When a data transfer takes place, if the STag refers to an
>   MR, then the PD ID of the MR is validated against the PD ID of the
>   QP. If they do not match, the data transfer generates an error and
>   no data transfer takes place. If the STag refers to an MW, then the
>   PD ID of the MW is validated against the PD ID of the QP when the MW
>   is Bound to the QP. When a data transfer takes place, the QP ID of
>   the MW is validated against the QP ID of the QP."
> 
> Tom, I read the above as an STag that represents a MR can be used by
any
> QP with the same PD ID. STags that represent a MW must be used on the
> same QP that created them.
> 
> - Doug
> 
> > This leverages the IP security model and provides correctness.
> > It is true that IB implementations generally don't do this. They
> should.
> >
> > Tom.
> >
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