Re: [PATCH v3] ima: add a new CONFIG for loading arch-specific policies

[Philipp Rudo <prudo@linux.ibm.com>]

On Sun,  8 Mar 2020 20:57:51 -0400
Nayna Jain <nayna@linux.ibm.com> wrote:

> From: Nayna Jain <nayna@linux.vnet.ibm.com>
> 
> Every time a new architecture defines the IMA architecture specific
> functions - arch_ima_get_secureboot() and arch_ima_get_policy(), the IMA
> include file needs to be updated. To avoid this "noise", this patch
> defines a new IMA Kconfig IMA_SECURE_AND_OR_TRUSTED_BOOT option, allowing
> the different architectures to select it.
> 
> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
> Acked-by: Ard Biesheuvel <ardb@kernel.org>
> Cc: Ard Biesheuvel <ardb@kernel.org>
> Cc: Philipp Rudo <prudo@linux.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> ---
> v3:
> * Removes CONFIG_IMA dependency. Thanks Ard.
> * Updated the patch with improvements suggested by Michael. It now uses
> "imply" instead of "select". Thanks Michael.
> * Replaced the CONFIG_IMA in x86 and s390 with new config, else it was
> resulting in redefinition when the IMA_SECURE_AND_OR_TRUSTED_BOOT
> is not enabled. Thanks to Mimi for identifying the problem.
> * Removed "#ifdef EFI" check in the arch/x86/Makefile for compiling
> ima_arch.c file.
> * Ard, Thanks for your Acked-by. I have changed the arch/x86/Makefile in
> this version. Can you please review again and confirm ?
> * Rudo, Thanks for your review. I have changed arch/s390/Makefile as well.
> Can you also please review again ?

Looks good to me

for the s390 part
Acked-by: Philipp Rudo <prudo@linux.ibm.com>

Thanks
Philipp

> 
> v2:
> * Fixed the issue identified by Mimi. Thanks Mimi, Ard, Heiko and Michael for
> discussing the fix.
> 
>  arch/powerpc/Kconfig           | 1 +
>  arch/s390/Kconfig              | 1 +
>  arch/s390/kernel/Makefile      | 2 +-
>  arch/x86/Kconfig               | 1 +
>  arch/x86/kernel/Makefile       | 4 +---
>  include/linux/ima.h            | 3 +--
>  security/integrity/ima/Kconfig | 7 +++++++
>  7 files changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 497b7d0b2d7e..5b9f1cba2a44 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -979,6 +979,7 @@ config PPC_SECURE_BOOT
>  	bool
>  	depends on PPC_POWERNV
>  	depends on IMA_ARCH_POLICY
> +	imply IMA_SECURE_AND_OR_TRUSTED_BOOT
>  	help
>  	  Systems with firmware secure boot enabled need to define security
>  	  policies to extend secure boot to the OS. This config allows a user
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index 8abe77536d9d..59c216af6264 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -195,6 +195,7 @@ config S390
>  	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
>  	select SWIOTLB
>  	select GENERIC_ALLOCATOR
> +	imply IMA_SECURE_AND_OR_TRUSTED_BOOT
>  
>  
>  config SCHED_OMIT_FRAME_POINTER
> diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
> index 2b1203cf7be6..578a6fa82ea4 100644
> --- a/arch/s390/kernel/Makefile
> +++ b/arch/s390/kernel/Makefile
> @@ -70,7 +70,7 @@ obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
>  obj-$(CONFIG_KEXEC_FILE)	+= machine_kexec_file.o kexec_image.o
>  obj-$(CONFIG_KEXEC_FILE)	+= kexec_elf.o
>  
> -obj-$(CONFIG_IMA)		+= ima_arch.o
> +obj-$(CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT)	+= ima_arch.o
>  
>  obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o perf_cpum_cf_common.o
>  obj-$(CONFIG_PERF_EVENTS)	+= perf_cpum_cf.o perf_cpum_sf.o
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index beea77046f9b..dcf5b1729f7c 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -230,6 +230,7 @@ config X86
>  	select VIRT_TO_BUS
>  	select X86_FEATURE_NAMES		if PROC_FS
>  	select PROC_PID_ARCH_STATUS		if PROC_FS
> +	imply IMA_SECURE_AND_OR_TRUSTED_BOOT    if EFI
>  
>  config INSTRUCTION_DECODER
>  	def_bool y
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 9b294c13809a..cfef37a27def 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -154,6 +154,4 @@ ifeq ($(CONFIG_X86_64),y)
>  	obj-y				+= vsmp_64.o
>  endif
>  
> -ifdef CONFIG_EFI
> -obj-$(CONFIG_IMA)			+= ima_arch.o
> -endif
> +obj-$(CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT)	+= ima_arch.o
> diff --git a/include/linux/ima.h b/include/linux/ima.h
> index 1659217e9b60..aefe758f4466 100644
> --- a/include/linux/ima.h
> +++ b/include/linux/ima.h
> @@ -30,8 +30,7 @@ extern void ima_kexec_cmdline(const void *buf, int size);
>  extern void ima_add_kexec_buffer(struct kimage *image);
>  #endif
>  
> -#if (defined(CONFIG_X86) && defined(CONFIG_EFI)) || defined(CONFIG_S390) \
> -	|| defined(CONFIG_PPC_SECURE_BOOT)
> +#ifdef CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT
>  extern bool arch_ima_get_secureboot(void);
>  extern const char * const *arch_get_ima_policy(void);
>  #else
> diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
> index 3f3ee4e2eb0d..edde88dbe576 100644
> --- a/security/integrity/ima/Kconfig
> +++ b/security/integrity/ima/Kconfig
> @@ -327,3 +327,10 @@ config IMA_QUEUE_EARLY_BOOT_KEYS
>  	depends on IMA_MEASURE_ASYMMETRIC_KEYS
>  	depends on SYSTEM_TRUSTED_KEYRING
>  	default y
> +
> +config IMA_SECURE_AND_OR_TRUSTED_BOOT
> +       bool
> +       depends on IMA_ARCH_POLICY
> +       help
> +          This option is selected by architectures to enable secure and/or
> +          trusted boot based on IMA runtime policies.