RE: [PATCH 0/6] Add Hygon SEV support

From: Pascal Van Leeuwen <pvanleeuwen@insidesecure.com>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Hao Feng" <fenghao@hygon.cn>,
	"'Tom Lendacky '" <thomas.lendacky@amd.com>,
	"'Gary Hook '" <gary.hook@amd.com>,
	"'Herbert Xu '" <herbert@gondor.apana.org.au>,
	"' David S. Miller '" <davem@davemloft.net>,
	"'Janakarajan Natarajan '" <Janakarajan.Natarajan@amd.com>,
	"'Joerg Roedel '" <joro@8bytes.org>,
	"' Radim Krčmář '" <rkrcmar@redhat.com>,
	"'Thomas Gleixner '" <tglx@linutronix.de>,
	"'Ingo Molnar '" <mingo@redhat.com>,
	"'Borislav Petkov '" <bp@alien8.de>,
	"' H. Peter Anvin '" <hpa@zytor.com>
Cc: 'Zhaohui Du ' <duzhaohui@hygon.cn>,
	'Zhiwei Ying ' <yingzhiwei@hygon.cn>, 'Wen Pu ' <puwen@hygon.cn>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 0/6] Add Hygon SEV support
Date: Tue, 16 Apr 2019 09:08:49 +0000	[thread overview]
Message-ID: <DBBPR09MB3526D65B174254E791553545D2240@DBBPR09MB3526.eurprd09.prod.outlook.com> (raw)
In-Reply-To: <985108b1-6d51-4458-48de-c5b96c5f14f9@redhat.com>

> >
> > Uhm ... no, the fact that something is actually *useful* to
> potentially
> > a billion plus people doesn't mean anything ...
>
> Useful does not mean secure, does it?  PKZIP encryption was certainly
> useful back in the day, but it was not secure.
>
"Secure" is a relative term anyway. There's always a trade-off between
performance, cost, power consumption and security. Different use cases
require different levels of security. IMHO that decision should be up
to the application / user / market, and not up to some software
engineers that are not experts on the subject matter anyway (but I am
hopeful that some people here are, in fact, experts to some extent).

> "Freedom" didn't apply when Speck was proposed for inclusion in Linux,
> and I would like to make sure I don't make a mistake when adding crypto
> interfaces.  If SM2/3/4 were broken, I couldn't care less if someone
> HAS to use them, they can patch their kernel.
>
Is Speck actually used in any real-life protocol or application?
I did not follow the Speck discussion but I have a hunch that was a far
more important reason not to include it than it being a weak cipher or
it's shady NSA origins ...

And yes, they can always fork the kernel and do their own stuff with it,
but that's going to be a support nightmare for people - like us - wanting
to add HW acceleration on top of that. And yes, "we" can do SM3 & SM4.
Full disclosure: it is in my/our interest to keep SM3 & SM4 in the tree.

>  But if they're not then I appreciate that you wrote to correct me,
> it's helpful.  Please
> understand that 99% of the community has not ever heard of anything but
> SHA-{1,2,3}, ECDSA, Ed25519, AES.  If somebody comes up with a patch
> with "strange" crypto, it's up to them to say that they are secure---
> and again, the key word is secure, not useful.
>
I recognise the fact that most people are not experts on the subject
matter. However, there's a lot you can find out in a short Google session
before you start a discussion on incorrect assumptions ...
Anyway, always happy to educate people a bit.

Regards,

Pascal van Leeuwen
Silicon IP Architect, Multi-Protocol Engines @ Inside Secure