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Date:   Thu, 7 Jul 2022 05:46:40 -0400
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Subject: Re: Linux DRTM on UEFI platforms
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To:     The development of GNU GRUB <grub-devel@gnu.org>,
        Brendan Trotter <btrotter@gmail.com>
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Matthew Garrett <mjg59@srcf.ucam.org>,
        Daniel Kiper <daniel.kiper@oracle.com>,
        Alec Brown <alec.r.brown@oracle.com>,
        Kanth Ghatraju <kanth.ghatraju@oracle.com>,
        Ross Philipson <ross.philipson@oracle.com>,
        "piotr.krol@3mdeb.com" <piotr.krol@3mdeb.com>,
        "krystian.hebel@3mdeb.com" <krystian.hebel@3mdeb.com>,
        "persaur@gmail.com" <persaur@gmail.com>,
        "Yoder, Stuart" <stuart.yoder@arm.com>,
        Andrew Cooper <andrew.cooper3@citrix.com>,
        "michal.zygowski@3mdeb.com" <michal.zygowski@3mdeb.com>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        "lukasz@hawrylko.pl" <lukasz@hawrylko.pl>,
        linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org,
        James Morris <jmorris@namei.org>
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From:   "Daniel P. Smith" <dpsmith@apertussolutions.com>
In-Reply-To: <CAELHeEfZ-feZnexp7Gx3VAJPerENcoO1Uccbe3xxUX95jvLUdA@mail.gmail.com>
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On 7/5/22 20:03, Brendan Trotter wrote:
> Hi,

Greetings!

Not sure why I got dropped from distro, but no worries.

> On Wed, Jul 6, 2022 at 4:52 AM Daniel P. Smith
> <dpsmith@apertussolutions.com> wrote:
>> On 6/10/22 12:40, Ard Biesheuvel wrote:> On Thu, 19 May 2022 at 22:59,
>> To help provide clarity, consider the following flows for comparison,
>>
>> Normal/existing efi-stub:
>>    EFI -> efi-stub -> head_64.S
>>
>> Proposed secure launch:
>>    EFI -> efi-stub -> dl-handler -> [cpu] -> sl_stub ->head_64.S
> 
> For more clarity; the entire point is to ensure that the kernel only
> has to trust itself and the CPU/TPM hardware (and does not have to
> trust a potentially malicious boot loader)..Any attempt to avoid a
> one-off solution for Linux is an attempt to weaken security.

Please elaborate so I might understand how this entrypoint allows for 
the kernel to only trust itself and the CPU/TPM.

> The only correct approach is "efi-stub -> head_64.S -> kernel's own
> secure init"; where (on UEFI systems) neither GRUB nor Trenchboot has
> a valid reason to exist and should never be installed.
> 
> 
> Cheers,
> 
> Brendan

v/r,
dps