linux-kernel - Re: [PATCH v2] x86/efi: Add additional efi tables for unencrypted mapping checks

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Message-ID: <CAKv+Gu8M5LMjA+JnJ57+BU4jmpgz0OqLyt1W9LXj_UDH=5DgjQ@mail.gmail.com>
Date:   Tue, 25 Feb 2020 20:28:26 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2] x86/efi: Add additional efi tables for unencrypted
 mapping checks

On Tue, 25 Feb 2020 at 20:21, Tom Lendacky <thomas.lendacky@....com> wrote:
>
> On 2/25/20 12:12 PM, Ard Biesheuvel wrote:
> > On Tue, 25 Feb 2020 at 19:10, Tom Lendacky <thomas.lendacky@....com> wrote:
> >>
> >> On 2/25/20 11:58 AM, Ard Biesheuvel wrote:
> >>> On Tue, 25 Feb 2020 at 18:54, Tom Lendacky <thomas.lendacky@....com> wrote:
> >>>>
> >>>> On 2/25/20 11:45 AM, Ard Biesheuvel wrote:
> >>>>> On Tue, 25 Feb 2020 at 18:41, Tom Lendacky <thomas.lendacky@....com> wrote:
> >>>>>>
> >>>>>> When booting with SME active, EFI tables must be mapped unencrypted since
> >>>>>> they were built by UEFI in unencrypted memory. Update the list of tables
> >>>>>> to be checked during early_memremap() processing to account for new EFI
> >>>>>> tables.
> >>>>>>
> >>>>>> This fixes a bug where an EFI TPM log table has been created by UEFI, but
> >>>>>> it lives in memory that has been marked as usable rather than reserved.
> >>>>>>
> >>>>>> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> >>>>>>
> >>>>>> ---
> >>>>>> Changes since v1:
> >>>>>> - Re-spun against EFI tree
> >>>>>
> >>>>> Which one? Surely not the one in the link I included?
> >>>>
> >>>> I did a git clone of
> >>>>
> >>>>   git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi.git
> >>>>
> >>>> and checked out branch next. Not sure what I missed...
> >>>>
> >>>
> >>> Weird. Do you see commit 5d288dbd88606d8f215c7138b10649115d79cadd on
> >>> that branch? It removes rng_seed from struct efi, hence my request to
> >>> rebase your patch.
> >>
> >> I had just assumed you wanted a cleaner version and didn't realize that
> >> rng_seed was removed from struct efi. My bad for not building.
> >>
> >>>
> >>> IMO, best is to simply drop the 'static' from rng_seed, rename it to
> >>> efi_rng_seed, and drop an extern declaration in linux/efi.h so it is
> >>> accessible from your code. I'm reluctant to put it back in struct efi.
> >>
> >> Ok, I'll re-work the patch.
> >>
> >
> > OK
> >
> > Btw if you want the TPM part of the fix to go to -stable, better to
> > split them in two (and I'll put a cc:stable on the tpm one)
>
> I had thought about stable, but the fix gets tricky since the two tables
> were added at different times (4.16 and 5.3) and the efi_tables array was
> moved from drivers/firmware/efi/efi.c to arch/x86/platform/efi/efi.c in 5.4.
>
> I could do the two TPM tables each as their own patch and add an
> appropriate Cc: stable # v4.16.x-, etc., if you don't think that's
> overkill. The array move shouldn't be too hard to adjust for in stable.
> Thoughts?
>

So v5.4/v5.5 seems straight-forward then, no? Once that one is in, we
can do one specially for v4.19