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Message-ID: <97b69bc79a5d9246f7a399510908c7b95b2e95e7.camel@linux.ibm.com>
Date: Fri, 16 Jan 2026 11:38:39 -0500
From: Mimi Zohar <zohar@...ux.ibm.com>
To: Ard Biesheuvel <ardb@...nel.org>
Cc: Coiby Xu <coxu@...hat.com>, linux-integrity@...r.kernel.org,
Heiko
Carstens <hca@...ux.ibm.com>,
Roberto Sassu
<roberto.sassu@...weicloud.com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Madhavan Srinivasan <maddy@...ux.ibm.com>,
Michael Ellerman <mpe@...erman.id.au>,
Nicholas Piggin
<npiggin@...il.com>,
"Christophe Leroy (CS GROUP)" <chleroy@...nel.org>,
Vasily Gorbik <gor@...ux.ibm.com>,
Alexander Gordeev
<agordeev@...ux.ibm.com>,
Christian Borntraeger
<borntraeger@...ux.ibm.com>,
Sven Schnelle <svens@...ux.ibm.com>,
Thomas
Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
Borislav
Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
"H.
Peter Anvin" <hpa@...or.com>,
Roberto Sassu <roberto.sassu@...wei.com>,
Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
Eric Snowberg
<eric.snowberg@...cle.com>,
Paul Moore <paul@...l-moore.com>, James Morris
<jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>,
Jarkko
Sakkinen <jarkko@...nel.org>,
"moderated list:ARM64 PORT (AARCH64
ARCHITECTURE)" <linux-arm-kernel@...ts.infradead.org>,
open list
<linux-kernel@...r.kernel.org>,
"open list:LINUX FOR POWERPC (32-BIT AND
64-BIT)" <linuxppc-dev@...ts.ozlabs.org>,
"open list:S390 ARCHITECTURE"
<linux-s390@...r.kernel.org>,
"open list:EXTENSIBLE FIRMWARE INTERFACE
(EFI)" <linux-efi@...r.kernel.org>,
"open list:SECURITY SUBSYSTEM"
<linux-security-module@...r.kernel.org>,
"open
list:KEYS/KEYRINGS_INTEGRITY" <keyrings@...r.kernel.org>
Subject: Re: [PATCH 1/3] integrity: Make arch_ima_get_secureboot
integrity-wide
On Fri, 2026-01-16 at 14:18 +0100, Ard Biesheuvel wrote:
> On Fri, 16 Jan 2026 at 14:11, Mimi Zohar <zohar@...ux.ibm.com> wrote:
> >
> > On Fri, 2026-01-16 at 10:41 +0100, Ard Biesheuvel wrote:
> > > On Thu, 15 Jan 2026 at 01:43, Coiby Xu <coxu@...hat.com> wrote:
> > > >
> > > > EVM and other LSMs need the ability to query the secure boot status of
> > > > the system, without directly calling the IMA arch_ima_get_secureboot
> > > > function. Refactor the secure boot status check into a general,
> > > > integrity-wide function named arch_integrity_get_secureboot.
> > > >
> > > > Define a new Kconfig option CONFIG_INTEGRITY_SECURE_BOOT, which is
> > > > automatically configured by the supported architectures. The existing
> > > > IMA_SECURE_AND_OR_TRUSTED_BOOT Kconfig loads the architecture specific
> > > > IMA policy based on the refactored secure boot status code.
> > > >
> > > > Reported-and-suggested-by: Mimi Zohar <zohar@...ux.ibm.com>
> > > > Suggested-by: Roberto Sassu <roberto.sassu@...weicloud.com>
> > > > Signed-off-by: Coiby Xu <coxu@...hat.com>
> > > > ---
> > > > arch/arm64/Kconfig | 1 +
> > > > arch/powerpc/Kconfig | 1 +
> > > > arch/powerpc/kernel/Makefile | 2 +-
> > > > arch/powerpc/kernel/ima_arch.c | 5 --
> > > > arch/powerpc/kernel/integrity_sb_arch.c | 13 +++++
> > > > arch/s390/Kconfig | 1 +
> > > > arch/s390/kernel/Makefile | 1 +
> > > > arch/s390/kernel/ima_arch.c | 6 --
> > > > arch/s390/kernel/integrity_sb_arch.c | 9 +++
> > > > arch/x86/Kconfig | 1 +
> > > > arch/x86/include/asm/efi.h | 4 +-
> > > > arch/x86/platform/efi/efi.c | 2 +-
> > > > include/linux/ima.h | 7 +--
> > > > include/linux/integrity.h | 8 +++
> > > > security/integrity/Kconfig | 6 ++
> > > > security/integrity/Makefile | 3 +
> > > > security/integrity/efi_secureboot.c | 56 +++++++++++++++++++
> > > > security/integrity/ima/ima_appraise.c | 2 +-
> > > > security/integrity/ima/ima_efi.c | 47 +---------------
> > > > security/integrity/ima/ima_main.c | 4 +-
> > > > security/integrity/platform_certs/load_uefi.c | 2 +-
> > > > 21 files changed, 111 insertions(+), 70 deletions(-)
> > > > create mode 100644 arch/powerpc/kernel/integrity_sb_arch.c
> > > > create mode 100644 arch/s390/kernel/integrity_sb_arch.c
> > > > create mode 100644 security/integrity/efi_secureboot.c
> > > >
> > > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > > > index 93173f0a09c7..4c265b7386bb 100644
> > > > --- a/arch/arm64/Kconfig
> > > > +++ b/arch/arm64/Kconfig
> > > > @@ -2427,6 +2427,7 @@ config EFI
> > > > select EFI_STUB
> > > > select EFI_GENERIC_STUB
> > > > imply IMA_SECURE_AND_OR_TRUSTED_BOOT
> > > > + imply INTEGRITY_SECURE_BOOT
> > >
> > > This allows both to be en/disabled individually, which I don't think
> > > is what we want. It also results in more churn across the
> > > arch-specific Kconfigs than needed.
> > >
> > > Wouldn't it be better if IMA_SECURE_AND_OR_TRUSTED_BOOT 'select'ed
> > > INTEGRITY_SECURE_BOOT in its Kconfig definition?
> >
> > As much as possible, EVM (and other LSMs) shouldn't be dependent on another LSM,
> > in this case IMA, being configured.
>
> Sure, but that is not my point.
>
> This arrangement allows for IMA_SECURE_AND_OR_TRUSTED_BOOT to be
> enabled without INTEGRITY_SECURE_BOOT, resulting in the stub
> implementation of arch_integrity_get_secureboot() being used, which
> always returns false.
I understand your concern, but instead of "select"ing INTEGRITY_SECURE_BOOT from
IMA_SECURE_AND_OR_TRUSTED_BOOT, how making IMA_SECURE_AND_OR_TRUSTED_BOOT
dependent on both IMA_ARCH_POLICY and INTEGRITY_SECURE_BOOT.
Including the "imply INTEGRITY_SECURE_BOOT" here in the arch Kconfig allows EVM
to query the secure boot state without relying on IMA_SECURE_AND_OR_TRUSTED_BOOT
being configured.
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