[PATCH 2/2] ima: Fail rule parsing when asymmetric key measurement isn't supportable

[Lakshmi Ramasubramanian]

On 7/27/20 7:08 AM, Tyler Hicks wrote:
> Measuring keys is currently only supported for asymmetric keys. In the
> future, this might change.
> 
> For now, the "func=KEY_CHECK" and "keyrings=" options are only
> appropriate when CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS is enabled. Make
> this clear at policy load so that IMA policy authors don't assume that
> these policy language constructs are supported.
> 
> Fixes: 2b60c0ecedf8 ("IMA: Read keyrings= option from the IMA policy")
> Fixes: 5808611cccb2 ("IMA: Add KEY_CHECK func to measure keys")
> Suggested-by: Nayna Jain <nayna at linux.ibm.com>
> Signed-off-by: Tyler Hicks <tyhicks at linux.microsoft.com>
> ---
>   security/integrity/ima/ima_policy.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index c328cfa0fc49..05f012fd3dca 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -1233,7 +1233,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
>   				entry->func = POLICY_CHECK;
>   			else if (strcmp(args[0].from, "KEXEC_CMDLINE") == 0)
>   				entry->func = KEXEC_CMDLINE;
> -			else if (strcmp(args[0].from, "KEY_CHECK") == 0)
> +			else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) &&
> +				 strcmp(args[0].from, "KEY_CHECK") == 0)
>   				entry->func = KEY_CHECK;
>   			else
>   				result = -EINVAL;
> @@ -1290,7 +1291,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
>   		case Opt_keyrings:
>   			ima_log_string(ab, "keyrings", args[0].from);
>   
> -			if (entry->keyrings) {
> +			if (!IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) ||
> +			    entry->keyrings) {
>   				result = -EINVAL;
>   				break;
>   			}
> 

Reviewed-by: Lakshmi Ramasubramanian <nramas at linux.microsoft.com>