linux-kernel - Re: [PATCH 1/3] integrity: Make arch_ima_get

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Message-ID: <CAMj1kXHsJNZoUEnbD1y=v4Ftuv9d2c08VckRV7ru4k4P83vZbQ@mail.gmail.com>
Date: Fri, 16 Jan 2026 14:18:48 +0100
From: Ard Biesheuvel <ardb@...nel.org>
To: Mimi Zohar <zohar@...ux.ibm.com>
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, 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.