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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 18:37:20 -0400
Message-ID: <8199b81d-7230-44d9-bddf-92af562fe6b1@apertussolutions.com> (raw)
In-Reply-To: <CACdnJusRATYv3Une5r14KHJVEg5COVW9B_BNViUXjavSxZ6d5A@mail.gmail.com>

On 3/26/20 4:54 PM, Matthew Garrett wrote:
> On Thu, Mar 26, 2020 at 1:50 PM Daniel P. Smith
> <dpsmith@apertussolutions.com> wrote:
>> It is not part of the EFI entry point as we are not entering the kernel
>> from EFI but I will address that further in my response to Andy. The
>> expectation is that if you are on an UEFI platform then EBS should have
>> already been called.
> 
> Ok. In that case should the EFI boot stub optionally be calling this
> instead of startup_32?
> 
>> With respect to using the firmware's TPM code, one
>> of the purposes of a TCG Dynamic Launch is to remove the firmware from
>> the code being trusted in making the integrity measurement of the
>> kernel. I trust the firmware to initialize the hardware because I have
>> to and it does give a trust chain, aka the SRTM, that can attest to what
>> was used during that process. When the OS kernel is being started that
>> trust chain has become weak (or even broken). I want a new trust chain
>> that can provide better footing for asserting the integrity of the
>> kernel and this is what Dynamic Launch gives us. I would like to think I
>> did a fair job explaining this at LSS last fall[1][2] and would
>> recommend those that are curious to review the slides/watch the
>> presentation.
> 
> 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.

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.


  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 [this message]
2020-03-26 22:41         ` Matthew Garrett
2020-03-26 23:55           ` Daniel P. Smith

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