[RFC PATCH] ima: require secure_boot rules in lockdown mode

[Mimi Zohar]

On Thu, 2017-11-02 at 17:11 +0000, David Howells wrote:
> I've made the revisions suggested.  See the attached patch.

It looks good, except for a mistake in the original I patch posted.

> ---
> commit 721c0994b824b91acd3c412abe55ae41287fc64d
> Author: Mimi Zohar <zohar at linux.vnet.ibm.com>
> Date:   Mon Oct 23 11:59:47 2017 -0400
> 
>     ima: require secure_boot rules in lockdown mode
>     
>     Require the "secure_boot" rules, whether or not it is specified
>     on the boot command line, for both the builtin and custom policies
>     in secure boot lockdown mode.
>     
>     Signed-off-by: Mimi Zohar <zohar at linux.vnet.ibm.com>
>     Signed-off-by: David Howells <dhowells at redhat.com>
> 
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 95209a5f8595..f64f2be2dc0c 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -427,14 +427,21 @@ void ima_update_policy_flag(void)
>   */
>  void __init ima_init_policy(void)
>  {
> -	int i, measure_entries, appraise_entries, secure_boot_entries;
> +	int i;
> +	int measure_entries = 0;
> +	int appraise_entries = 0;
> +	int secure_boot_entries = 0;
> +	bool kernel_locked_down = kernel_is_locked_down();

kernel_is_locked_down() requires a string.

Mimi

> 
>  	/* if !ima_policy set entries = 0 so we load NO default rules */
> -	measure_entries = ima_policy ? ARRAY_SIZE(dont_measure_rules) : 0;
> -	appraise_entries = ima_use_appraise_tcb ?
> -			 ARRAY_SIZE(default_appraise_rules) : 0;
> -	secure_boot_entries = ima_use_secure_boot ?
> -			ARRAY_SIZE(secure_boot_rules) : 0;
> +	if (ima_policy)
> +		measure_entries = ARRAY_SIZE(dont_measure_rules);
> +
> +	if (ima_use_appraise_tcb)
> +		appraise_entries = ARRAY_SIZE(default_appraise_rules);
> +
> +	if (ima_use_secure_boot || kernel_locked_down)
> +		secure_boot_entries = ARRAY_SIZE(secure_boot_rules);
> 
>  	for (i = 0; i < measure_entries; i++)
>  		list_add_tail(&dont_measure_rules[i].list, &ima_default_rules);
> @@ -455,11 +462,23 @@ void __init ima_init_policy(void)
> 
>  	/*
>  	 * Insert the appraise rules requiring file signatures, prior to
> -	 * any other appraise rules.
> +	 * any other appraise rules.  In secure boot lock-down mode, also
> +	 * require these appraise rules for custom policies.
>  	 */
> -	for (i = 0; i < secure_boot_entries; i++)
> -		list_add_tail(&secure_boot_rules[i].list,
> -			      &ima_default_rules);
> +	for (i = 0; i < secure_boot_entries; i++) {
> +		struct ima_rule_entry *entry;
> +
> +		/* Include for builtin policies */
> +		list_add_tail(&secure_boot_rules[i].list, &ima_default_rules);
> +
> +		/* Include for custom policies */
> +		if (kernel_locked_down) {
> +			entry = kmemdup(&secure_boot_rules[i], sizeof(*entry),
> +					GFP_KERNEL);
> +			if (entry)
> +				list_add_tail(&entry->list, &ima_policy_rules);
> +		}
> +	}
> 
>  	for (i = 0; i < appraise_entries; i++) {
>  		list_add_tail(&default_appraise_rules[i].list,
> --
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