linux-kernel - Re: [PATCH] ima: require signed IMA policy when UEFI secure boot is enabled

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Date:   Tue, 04 Jul 2023 08:57:10 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Coiby Xu <coxu@...hat.com>, linux-integrity@...r.kernel.org
Cc:     Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        Paul Moore <paul@...l-moore.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        "open list:SECURITY SUBSYSTEM" 
        <linux-security-module@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ima: require signed IMA policy when UEFI secure boot is
 enabled

On Mon, 2023-07-03 at 19:54 +0800, Coiby Xu wrote:
> With the introduction of the .machine keyring for UEFI-based systems,
> users are able to add custom CAs keys via MOK. This allow users to sign
> their own IMA polices. For the sake of security, mandate signed IMA
> policy when UEFI secure boot is enabled.
> 
> Suggested-by: Mimi Zohar <zohar@...ux.ibm.com>
> Signed-off-by: Coiby Xu <coxu@...hat.com>
> ---
>  security/integrity/ima/ima_efi.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/security/integrity/ima/ima_efi.c b/security/integrity/ima/ima_efi.c
> index 9db66fe310d4..bb2881759505 100644
> --- a/security/integrity/ima/ima_efi.c
> +++ b/security/integrity/ima/ima_efi.c
> @@ -58,6 +58,9 @@ static const char * const sb_arch_rules[] = {
>  #if !IS_ENABLED(CONFIG_MODULE_SIG)
>  	"appraise func=MODULE_CHECK appraise_type=imasig",
>  #endif
> +#if IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING) && IS_ENABLED(CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY)
> +	"appraise func=POLICY_CHECK appraise_type=imasig",
> +#endif /* CONFIG_INTEGRITY_MACHINE_KEYRING && IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY */
>  	"measure func=MODULE_CHECK",
>  	NULL
>  };

Thanks, Coiby.

Using IS_ENABLED() is not wrong, but unnecessary.  IS_BUILTIN()
suffices.

-- 
thanks,

Mimi