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From: "Daniel P. Smith" <dpsmith@apertussolutions.com>
To: Matthew Garrett <mjg59@google.com>
Cc: Ross Philipson <ross.philipson@oracle.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	linux-doc@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	trenchboot-devel@googlegroups.com
Subject: Re: [RFC PATCH 00/12] x86: Trenchboot secure late launch Linux kernel support
Date: Thu, 26 Mar 2020 19:55:05 -0400
Message-ID: <f64bc672-0c6e-d3f5-4b6c-4e60186d720c@apertussolutions.com> (raw)
In-Reply-To: <CACdnJuvxSaF96PkCiDp5u+599+bU5SnXRgLyWetaOKa0+1UqAg@mail.gmail.com>

On 3/26/20 6:41 PM, Matthew Garrett wrote:
> On Thu, Mar 26, 2020 at 3:37 PM Daniel P. Smith
> <dpsmith@apertussolutions.com> wrote:
>> On 3/26/20 4:54 PM, Matthew Garrett wrote:
>>> PCs depend on the availability of EFI runtime services - it's not
>>> possible to just assert that they're untrusted and so unsupported. The
>>> TPM code is part of boot services which (based on your design) are
>>> unavailable at this point, so I agree that you need your own
>>> implementation.
>>>
>>
>> I appreciate this has been a heated area of debate, but with all due
>> respect that might be a slight over statement w.r.t. dependency on
>> runtime services and not what I was saying about the trustworthiness of
>> UEFI. If I have a UEFI platform, I trust EFI to boot the system but that
>> does not mean I have to trust it to measure my OS kernel or manage the
>> running system. Secure Launch provides a means to start a measurement
>> trust chain starting with CPU taking the first measurement and then I
>> can do things like disabling runtime services in the kernel or do crazy
>> things like using the dynamic launch to switch to a minimal temporary
>> kernel that can do high trust operations such as interfacing with
>> entities outside your trust boundary, e.g. runtime services.
> 
> I understand. However, it is *necessary* for EFI runtime services to
> be available somehow, and this design needs to make that possible.
> Either EFI runtime services need to be considered part of the TCB, or
> we need a mechanism to re-verify the state of the system after making
> an EFI call (such as Andy's suggestion).
> 

Yes if you are on UEFI you will eventually need to deal with RS during
the system's lifetime, unless you don't want to patch your firmware
which I won't comment on what kind of idea that is. And yes I have been
chatting with a few people in the LinuxBoot community about re-verifying
the RS. The answer seemed to be that it might be possible but it doesn't
look like it will be trivial.

>> Please understand I really do not want my own implementation. I tried to
>> see if we could just #include in the minimal needed parts from the
>> in-tree TPM driver but could not find a clean way to do so. Perhaps
>> there might be a future opportunity to collaborate with the TPM driver
>> maintainers to refactor in a way that we can just reuse instead of
>> reimplement.
> 
> I think it's reasonable to assert that boot services can't be part of
> the TCB in this case, and as a result you're justified in not using
> the firmware's TPM implementation. However, we still need a solution
> for access to runtime services.
> 


      reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-25 19:43 Ross Philipson
2020-03-25 19:43 ` [RFC PATCH 01/12] x86: Secure Launch Kconfig Ross Philipson
2020-03-26 18:06   ` Daniel Kiper
2020-03-26 19:42     ` Ross Philipson
2020-03-25 19:43 ` [RFC PATCH 02/12] x86: Secure Launch main header file Ross Philipson
2020-03-26 19:00   ` Daniel Kiper
2020-03-25 19:43 ` [RFC PATCH 03/12] x86: Add early SHA support for Secure Launch early measurements Ross Philipson
2020-03-26  3:44   ` Andy Lutomirski
2020-03-26 22:49     ` Daniel P. Smith
2020-03-25 19:43 ` [RFC PATCH 04/12] x86: Add early TPM TIS/CRB interface support for Secure Launch Ross Philipson
2020-03-25 19:43 ` [RFC PATCH 05/12] x86: Add early TPM1.2/TPM2.0 " Ross Philipson
2020-03-25 19:43 ` [RFC PATCH 06/12] x86: Add early general TPM " Ross Philipson
2020-03-25 19:43 ` [RFC PATCH 07/12] x86: Secure Launch kernel early boot stub Ross Philipson
2020-03-25 19:43 ` [RFC PATCH 08/12] x86: Secure Launch kernel late " Ross Philipson
2020-03-25 19:43 ` [RFC PATCH 09/12] x86: Secure Launch SMP bringup support Ross Philipson
2020-03-25 19:43 ` [RFC PATCH 10/12] x86: Secure Launch adding event log securityfs Ross Philipson
2020-03-25 20:21   ` Matthew Garrett
2020-03-25 21:43     ` Daniel P. Smith
2020-03-25 19:43 ` [RFC PATCH 11/12] kexec: Secure Launch kexec SEXIT support Ross Philipson
2020-03-25 19:43 ` [RFC PATCH 12/12] tpm: Allow locality 2 to be set when initializing the TPM for Secure Launch Ross Philipson
2020-03-25 20:29 ` [RFC PATCH 00/12] x86: Trenchboot secure late launch Linux kernel support Matthew Garrett
2020-03-25 22:51   ` Andy Lutomirski
2020-03-26 20:50     ` Daniel P. Smith
2020-03-26 23:13       ` Andy Lutomirski
2020-05-11 19:00         ` Daniel P. Smith
2020-03-26 13:40   ` Daniel Kiper
2020-03-26 20:19     ` Matthew Garrett
2020-03-26 20:33       ` Andy Lutomirski
2020-03-26 20:40         ` Matthew Garrett
2020-03-26 20:59           ` Daniel P. Smith
2020-03-26 21:07           ` Andy Lutomirski
2020-03-26 21:28             ` Matthew Garrett
2020-03-26 22:52               ` Andy Lutomirski
2020-03-26 22:59                 ` Matthew Garrett
2020-03-26 23:04                   ` Andy Lutomirski
2020-03-27  0:01                     ` Daniel P. Smith
2020-03-26 23:50                 ` Daniel P. Smith
2020-05-11 19:00       ` Daniel P. Smith
2020-03-26 20:50   ` Daniel P. Smith
2020-03-26 20:54     ` Matthew Garrett
2020-03-26 22:37       ` Daniel P. Smith
2020-03-26 22:41         ` Matthew Garrett
2020-03-26 23:55           ` Daniel P. Smith [this message]

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