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

[Carlos Bilbao <carlos.bilbao@amd.com>]

On 4/27/23 7:29 AM, Reshetova, Elena wrote:
>> On Wed, Apr 26, 2023, Carlos Bilbao wrote:
>>> On 4/26/23 2:53 PM, Sean Christopherson wrote:
>>>> On Wed, Apr 26, 2023, Carlos Bilbao wrote:
>>>>> On 4/26/23 10:51 AM, Sean Christopherson wrote:
>>>>>> This document is named confidential-computing.rst, not tdx-and-snp.rst.
>> Not
>>>>>> explicitly mentioning SEV doesn't magically warp reality to make
>> descriptions like
>>>>>> this one from security/secrets/coco.rst disappear:
>>>>>>
>>>>>>   Introduction
>>>>>>   ============
>>>>>>
>>>>>>   Confidential Computing (coco) hardware such as AMD SEV (Secure
>> Encrypted
>>>>>>   Virtualization) allows guest owners to inject secrets into the VMs
>>>>>>   memory without the host/hypervisor being able to read them.
>>>>>>
>>>>>> My complaint about this document being too Intel/AMD centric isn't that it
>> doesn't
>>>>>> mention other implementations, it's that the doc describes CoCo purely
>> from the
>>>>>> narrow viewpoint of Intel TDX and AMD SNP, and to be blunt, reads like a
>> press
>>>>>> release and not an objective overview of CoCo.
>>>>>
>>>>> Be specific about the parts of the document that you feel are too
>>>>> AMD/Intel centric, and we will correct them.
>>>>
>>>> The whole thing?  There aren't specific parts that are too SNP/TDX centric, the
>>>> entire tone and approach of the document is wrong.  As I responded to Dave,
>> I
>>>> would feel differently if the document were named tdx-and-snp-threat-
>> model.rst,
>>>> but this patch proposes a generic confidential-computing.rst and presents the
>>>> SNP+TDX confidential VM use case as if it's the *only* confidential computing
>> use
>>>> case.
>>>
>>> What part of us describing the current Linux kernel threat model or
>>> defining basic concepts of confidential computing is SNP/TDX centric?
>>>
>>> IMHO, simply stating that "the whole thing" is wrong and that you don't
>>> like the "tone", is not making a good enough case for us to change
>>> anything, including the name of the document.
>>
>> I honestly don't know how to respond since you are either unable or unwilling to
>> see the problems with naming a document "confidential computing" and then
>> talking
>> only about one very, very specific flavor of confidential computing as if that is
>> the only flavor of confidential computing.
> 
> This is simply an unfair statement. I replied yesterday on this particular angle, i.e.
> let's think on how to name this properly: explained our thinking behind using the 
> "Confidential Cloud Computing" term (with references to academia using it) and asked
> what the better name should be. I didn’t get a reply to that, but here you say we
> are not willing to cooperate...
> 
> So I don’t think it is fair to say that we don’t take feedback! 
> 
> I agree with Dave that I think the goal of this document is not to come up with a
> fancy name (I am fine with call it anything), but to introduce kernel developers to the 
> new Linux threat model angle for this-particular-use-case-of-confidential-computing.
> So that when we submit the hardening mechanisms in the future people are 
> already familiar with why we need to do this and we don’t have to repeat this story 
> again and again. 

Yes! To reiterate, there's two things we definitely wish to do:

1. Narrow down the problem: This new document can be specific to CoCo in
   virtual environments. v2 should be clear about that.

2. Gather feedback: we already received some input about potential bias
   toward TDX/SNP, which should be addressed on v2.

Thanks,
Carlos

> 
> Best Regards,
> Elena.