On Fri, 16 Jan 2026 at 17:39, Mimi Zohar <[email protected]> wrote: > > On Fri, 2026-01-16 at 14:18 +0100, Ard Biesheuvel wrote: > > On Fri, 16 Jan 2026 at 14:11, Mimi Zohar <[email protected]> wrote: > > > > > > On Fri, 2026-01-16 at 10:41 +0100, Ard Biesheuvel wrote: > > > > On Thu, 15 Jan 2026 at 01:43, Coiby Xu <[email protected]> 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 <[email protected]> > > > > > Suggested-by: Roberto Sassu <[email protected]> > > > > > Signed-off-by: Coiby Xu <[email protected]> > > > > > --- > > > > > 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. >
Given that INTEGRITY_SECURE_BOOT has no dependencies of its own, afaict, selecting it is the least disruptive option, as otherwise, existing configs will disable IMA_SECURE_AND_OR_TRUSTED_BOOT as the kernel is being upgraded. But conceptually, I agree that they are equivalent. > 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. Yes, I understand that this is the whole point of the exercise. But 'imply' should be used with care, and in this case, implying both from CONFIG_EFI really makes little sense. INTEGRITY_SECURE_BOOT should be selected by options that need the functionality, not 'implied' by options that might provide it.
