linux-kernel - Re: [PATCH v8 4/8] powerpc/ima: add measurement rules to ima arch specific policy

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Date:   Sat, 19 Oct 2019 20:16:50 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Nayna Jain <nayna@...ux.ibm.com>, linuxppc-dev@...abs.org,
        linux-efi@...r.kernel.org, linux-integrity@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>,
        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>,
        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>,
        Prakhar Srivastava <prsriva02@...il.com>,
        Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
Subject: Re: [PATCH v8 4/8] powerpc/ima: add measurement rules to ima arch
 specific policy

On Sat, 2019-10-19 at 14:06 -0400, Nayna Jain wrote:
> This patch adds the measurement rules to the arch specific policies on
> trusted boot enabled systems.

This version does not add rules to the existing arch specific policy,
but defines an arch specific trusted boot only policy and a combined
secure and trusted boot policy.

> 
> Signed-off-by: Nayna Jain <nayna@...ux.ibm.com>
> ---
>  arch/powerpc/kernel/ima_arch.c | 34 +++++++++++++++++++++++++++++++++-
>  1 file changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/ima_arch.c b/arch/powerpc/kernel/ima_arch.c
> index 65d82ee74ea4..710872ea8f35 100644
> --- a/arch/powerpc/kernel/ima_arch.c
> +++ b/arch/powerpc/kernel/ima_arch.c
> @@ -26,6 +26,32 @@ static const char *const secure_rules[] = {
>  	NULL
>  };
>  
> +/*
> + * The "measure_rules" are enabled only on "trustedboot" enabled systems.

Please update the policy name to reflect the new "trusted_rules" name.

> + * These rules add the kexec kernel image and kernel modules file hashes to
> + * the IMA measurement list.
> + */
> +static const char *const trusted_rules[] = {
> +	"measure func=KEXEC_KERNEL_CHECK",
> +	"measure func=MODULE_CHECK",
> +	NULL
> +};
> +
> +/*
> + * The "secure_and_trusted_rules" contains rules for both the secure boot and
> + * trusted boot. The "template=ima-modsig" option includes the appended
> + * signature, when available, in the IMA measurement list.
> + */
> +static const char *const secure_and_trusted_rules[] = {
> +	"measure func=KEXEC_KERNEL_CHECK template=ima-modsig",
> +	"measure func=MODULE_CHECK template=ima-modsig",
> +	"appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig",
> +#ifndef CONFIG_MODULE_SIG_FORCE
> +	"appraise func=MODULE_CHECK appraise_type=imasig|modsig",
> +#endif
> +	NULL
> +};
> +
>  /*
>   * Returns the relevant IMA arch-specific policies based on the system secure
>   * boot state.
> @@ -33,7 +59,13 @@ static const char *const secure_rules[] = {
>  const char *const *arch_get_ima_policy(void)
>  {
>  	if (is_ppc_secureboot_enabled())
> -		return secure_rules;
> +		if (is_ppc_trustedboot_enabled())
> +			return secure_and_trusted_rules;
> +		else
> +			return secure_rules;
> +	else
> +		if (is_ppc_trustedboot_enabled())

No need for the "if" statement to be on a separate line.  Please
combine the "else" and "if" statements.

Mimi

> +			return trusted_rules;
>  
>  	return NULL;
>  }