linux-kernel - Re: [PATCH v2] ima: add a new CONFIG for loading arch-specific policies

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Message-ID: <CAKv+Gu831SRo+Di6WgKTex40TcOVqNQAdeNLtfQpPdgnvrxucw@mail.gmail.com>
Date:   Wed, 4 Mar 2020 08:14:42 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Nayna Jain <nayna@...ux.ibm.com>
Cc:     linux-integrity <linux-integrity@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        linux-s390 <linux-s390@...r.kernel.org>,
        Philipp Rudo <prudo@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] ima: add a new CONFIG for loading arch-specific policies

On Wed, 4 Mar 2020 at 03:34, Nayna Jain <nayna@...ux.ibm.com> wrote:
>
> 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@...ux-foundation.org>
> Signed-off-by: Nayna Jain <nayna@...ux.ibm.com>
> Cc: Ard Biesheuvel <ardb@...nel.org>
> Cc: Philipp Rudo <prudo@...ux.ibm.com>
> Cc: Michael Ellerman <mpe@...erman.id.au>

Acked-by: Ard Biesheuvel <ardb@...nel.org>

for the x86 bits, but I'm not an x86 maintainer. Also, you may need to
split this if you want to permit arch maintainers to pick up their
parts individually.


> ---
> 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/x86/Kconfig               | 1 +
>  include/linux/ima.h            | 3 +--
>  security/integrity/ima/Kconfig | 9 +++++++++
>  5 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 497b7d0b2d7e..a5cfde432983 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
> +       select 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..4a502fbcb800 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
> +       select IMA_SECURE_AND_OR_TRUSTED_BOOT if IMA_ARCH_POLICY
>
>
>  config SCHED_OMIT_FRAME_POINTER
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index beea77046f9b..7f5bfaf0cbd2 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
> +       select IMA_SECURE_AND_OR_TRUSTED_BOOT   if EFI && IMA_ARCH_POLICY
>
>  config INSTRUCTION_DECODER
>         def_bool y
> 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..d17972aa413a 100644
> --- a/security/integrity/ima/Kconfig
> +++ b/security/integrity/ima/Kconfig
> @@ -327,3 +327,12 @@ 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
> +       depends on IMA_ARCH_POLICY

Doesn't the latter already depend on the former?

> +       default n
> +       help
> +          This option is selected by architectures to enable secure and/or
> +          trusted boot based on IMA runtime policies.
> --
> 2.13.6
>