linux-kernel - Re: [PATCH v7 4/4] powerpc: load firmware trusted keys/hashes into kernel keyring

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Message-ID: <87eeyi4scd.fsf@mpe.ellerman.id.au>
Date:   Fri, 08 Nov 2019 20:42:26 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Eric Richter <erichte@...ux.ibm.com>, linuxppc-dev@...abs.org,
        linux-efi@...r.kernel.org, linux-integrity@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Jeremy Kerr <jk@...abs.org>,
        Matthew Garret <matthew.garret@...ula.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Claudio Carvalho <cclaudio@...ux.ibm.com>,
        George Wilson <gcwilson@...ux.ibm.com>,
        Elaine Palmer <erpalmer@...ibm.com>,
        Eric Ricther <erichte@...ux.ibm.com>,
        Oliver O'Halloran <oohall@...il.com>,
        Nayna Jain <nayna@...ux.ibm.com>
Subject: Re: [PATCH v7 4/4] powerpc: load firmware trusted keys/hashes into kernel keyring

Eric Richter <erichte@...ux.ibm.com> writes:
> From: Nayna Jain <nayna@...ux.ibm.com>
>
> The keys used to verify the Host OS kernel are managed by firmware as
> secure variables. This patch loads the verification keys into the .platform
> keyring and revocation hashes into .blacklist keyring. This enables
> verification and loading of the kernels signed by the boot time keys which
> are trusted by firmware.
>
> Signed-off-by: Nayna Jain <nayna@...ux.ibm.com>
> Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
> Signed-off-by: Eric Richter <erichte@...ux.ibm.com>
> ---
>  arch/powerpc/Kconfig                          |  1 +
>  security/integrity/Kconfig                    |  8 ++
>  security/integrity/Makefile                   |  4 +-
>  .../integrity/platform_certs/load_powerpc.c   | 98 +++++++++++++++++++
>  4 files changed, 110 insertions(+), 1 deletion(-)
>  create mode 100644 security/integrity/platform_certs/load_powerpc.c
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index cabc091f3fe1..498967a5ef4e 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -939,6 +939,7 @@ config PPC_SECURE_BOOT
>  	bool
>  	depends on PPC_POWERNV
>  	depends on IMA_ARCH_POLICY
> +	select LOAD_PPC_KEYS

This gave me a warning:

WARNING: unmet direct dependencies detected for LOAD_PPC_KEYS
  Depends on [n]: INTEGRITY [=y] && INTEGRITY_PLATFORM_KEYRING [=n] && PPC_SECURE_BOOT [=y]
  Selected by [y]:
  - PPC_SECURE_BOOT [=y] && PPC_POWERNV [=y] && IMA_ARCH_POLICY [=y]

I think you should probably just drop the select ..

> diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig
> index 0bae6adb63a9..26abee23e4e3 100644
> --- a/security/integrity/Kconfig
> +++ b/security/integrity/Kconfig
> @@ -72,6 +72,14 @@ config LOAD_IPL_KEYS
>         depends on S390
>         def_bool y
>  
> +config LOAD_PPC_KEYS
> +	bool "Enable loading of platform and blacklisted keys for POWER"
> +	depends on INTEGRITY_PLATFORM_KEYRING
> +	depends on PPC_SECURE_BOOT
> +	help
> +	  Enable loading of keys to the .platform keyring and blacklisted
> +	  hashes to the .blacklist keyring for powerpc based platforms.

And instead make this default y, if you think it should be enabled by
default when its prerequisites are met.

cheers