linux-kernel - Re: [PATCH 10/12] ima: Move validation of the keyrings conditional into ima_validate

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Date:   Thu, 25 Jun 2020 14:50:17 -0500
From:   Tyler Hicks <tyhicks@...ux.microsoft.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>
Cc:     James Morris <jmorris@...ei.org>,
        "Serge E . Hallyn" <serge@...lyn.com>,
        Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
        Prakhar Srivastava <prsriva02@...il.com>,
        linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org
Subject: Re: [PATCH 10/12] ima: Move validation of the keyrings conditional
 into ima_validate_rule()

On 2020-06-22 19:32:34, Tyler Hicks wrote:
> Use ima_validate_rule() to ensure that the combination of a hook
> function and the keyrings conditional is valid and that the keyrings
> conditional is not specified without an explicit KEY_CHECK func
> conditional. This is a code cleanup and has no user-facing change.
> 
> Signed-off-by: Tyler Hicks <tyhicks@...ux.microsoft.com>
> ---
>  security/integrity/ima/ima_policy.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 514baf24d6a5..ae2ec2a9cdb9 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -999,6 +999,12 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
>  		case KEXEC_KERNEL_CHECK:
>  		case KEXEC_INITRAMFS_CHECK:
>  		case POLICY_CHECK:
> +			if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
> +					     IMA_UID | IMA_FOWNER | IMA_FSUUID |
> +					     IMA_INMASK | IMA_EUID | IMA_PCR |
> +					     IMA_FSNAME))

I accidentally left these out:

 (IMA_DIGSIG_REQUIRED | IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED | IMA_CHECK_BLACKLIST)

I'll add them in v2.

Tyler

> +				return false;
> +
>  			break;
>  		case KEXEC_CMDLINE:
>  			if (entry->action & ~(MEASURE | DONT_MEASURE))
> @@ -1026,7 +1032,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
>  		default:
>  			return false;
>  		}
> -	}
> +	} else if (entry->flags & IMA_KEYRINGS)
> +		return false;
>  
>  	return true;
>  }
> @@ -1208,7 +1215,6 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
>  			keyrings_len = strlen(args[0].from) + 1;
>  
>  			if ((entry->keyrings) ||
> -			    (entry->func != KEY_CHECK) ||
>  			    (keyrings_len < 2)) {
>  				result = -EINVAL;
>  				break;
> -- 
> 2.25.1