Re: [PATCH] docs: security: Confidential computing intro and threat model

From: James Bottomley <jejb@linux.ibm.com>
To: "Reshetova, Elena" <elena.reshetova@intel.com>, "Christopherson, ,
	Sean" <seanjc@google.com>, Carlos Bilbao <carlos.bilbao@amd.com>
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Subject: Re: [PATCH] docs: security: Confidential computing intro and threat model
Date: Wed, 26 Apr 2023 11:18:03 -0400	[thread overview]
Message-ID: <7502e1af0615c08167076ff452fc69ebf316c730.camel@linux.ibm.com> (raw)
In-Reply-To: <DM8PR11MB575046B6DAA17B41FFED8080E7659@DM8PR11MB5750.namprd11.prod.outlook.com>

On Wed, 2023-04-26 at 13:32 +0000, Reshetova, Elena wrote:
> > On Mon, Mar 27, 2023, Carlos Bilbao wrote:
[...]
> > > +provide stronger security guarantees to their clients (usually
> > > referred to +as tenants) by excluding all the CSP's
> > > infrastructure and SW out of the +tenant's Trusted Computing Base
> > > (TCB).
> > 
> > This is inaccurate, the provider may still have software and/or
> > hardware in the TCB.
> 
> Well, this is the end goal where we want to be, the practical
> deployment can differ of course. We can rephrase that it "allows to
> exclude all the CSP's infrastructure and SW out of tenant's TCB." 

That's getting even more inaccurate.  To run  in a Cloud with CoCo you
usually have to insert some provided code, like OVMF and, for AMD, the
SVSM.  These are often customized by the CSP to suit the cloud
infrastructure, so you're running their code.  The goal, I think, is to
make sure you only run code you trust (some of which may come from the
CSP) in your TCB, which is very different from the statement above.

James