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Message-Id: <1538050608.3459.83.camel@linux.ibm.com>
Date: Thu, 27 Sep 2018 08:16:48 -0400
From: Mimi Zohar <zohar@...ux.ibm.com>
To: Nayna Jain <nayna@...ux.vnet.ibm.com>,
linux-integrity@...r.kernel.org
Cc: linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org,
linux-kernel@...r.kernel.org, dhowells@...hat.com,
jforbes@...hat.com
Subject: Re: [PATCH v4 3/6] ima: refactor ima_init_policy()
On Wed, 2018-09-26 at 17:52 +0530, Nayna Jain wrote:
> This patch removes the code duplication in ima_init_policy() by defining
> a new function named add_rules().
Thanks! The patch looks good, but let's expand on this just a bit.
Rules can be added to the initial IMA policy, the custom policy or
both, based on a mask (IMA_DEFAULT_POLICY, IMA_CUSTOM_POLICY).
Mimi
>
> Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
> ---
> security/integrity/ima/ima_policy.c | 98 +++++++++++++++++++++----------------
> 1 file changed, 57 insertions(+), 41 deletions(-)
>
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 8c9499867c91..d5b327320d3a 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -58,6 +58,8 @@ enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
>
> enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB };
>
> +enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY };
> +
> struct ima_rule_entry {
> struct list_head list;
> int action;
> @@ -473,6 +475,33 @@ static int ima_appraise_flag(enum ima_hooks func)
> return 0;
> }
>
> +static void add_rules(struct ima_rule_entry *entries, int count,
> + enum policy_rule_list file)
> +{
> + int i = 0;
> +
> + for (i = 0; i < count; i++) {
> + struct ima_rule_entry *entry;
> +
> + if (file & IMA_DEFAULT_POLICY)
> + list_add_tail(&entries[i].list, &ima_default_rules);
> +
> + if (file & IMA_CUSTOM_POLICY) {
> + entry = kmemdup(&entries[i], sizeof(*entry),
> + GFP_KERNEL);
> + if (!entry)
> + continue;
> +
> + INIT_LIST_HEAD(&entry->list);
> + list_add_tail(&entry->list, &ima_policy_rules);
> + }
> + if (entries[i].action == APPRAISE)
> + temp_ima_appraise |= ima_appraise_flag(entries[i].func);
> + if (entries[i].func == POLICY_CHECK)
> + temp_ima_appraise |= IMA_APPRAISE_POLICY;
> + }
> +}
> +
> /**
> * ima_init_policy - initialize the default measure rules.
> *
> @@ -481,28 +510,23 @@ static int ima_appraise_flag(enum ima_hooks func)
> */
> void __init ima_init_policy(void)
> {
> - int i, measure_entries, appraise_entries, secure_boot_entries;
> -
> - /* 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;
> + int build_appraise_entries;
>
> - for (i = 0; i < measure_entries; i++)
> - list_add_tail(&dont_measure_rules[i].list, &ima_default_rules);
> + /* if !ima_policy, we load NO default rules */
> + if (ima_policy)
> + add_rules(dont_measure_rules, ARRAY_SIZE(dont_measure_rules),
> + IMA_DEFAULT_POLICY);
>
> switch (ima_policy) {
> case ORIGINAL_TCB:
> - for (i = 0; i < ARRAY_SIZE(original_measurement_rules); i++)
> - list_add_tail(&original_measurement_rules[i].list,
> - &ima_default_rules);
> + add_rules(original_measurement_rules,
> + ARRAY_SIZE(original_measurement_rules),
> + IMA_DEFAULT_POLICY);
> break;
> case DEFAULT_TCB:
> - for (i = 0; i < ARRAY_SIZE(default_measurement_rules); i++)
> - list_add_tail(&default_measurement_rules[i].list,
> - &ima_default_rules);
> + add_rules(default_measurement_rules,
> + ARRAY_SIZE(default_measurement_rules),
> + IMA_DEFAULT_POLICY);
> default:
> break;
> }
> @@ -511,38 +535,30 @@ void __init ima_init_policy(void)
> * Insert the builtin "secure_boot" policy rules requiring file
> * signatures, prior to any other appraise rules.
> */
> - for (i = 0; i < secure_boot_entries; i++) {
> - list_add_tail(&secure_boot_rules[i].list, &ima_default_rules);
> - temp_ima_appraise |=
> - ima_appraise_flag(secure_boot_rules[i].func);
> - }
> + if (ima_use_secure_boot)
> + add_rules(secure_boot_rules, ARRAY_SIZE(secure_boot_rules),
> + IMA_DEFAULT_POLICY);
>
> /*
> * Insert the build time appraise rules requiring file signatures
> * for both the initial and custom policies, prior to other appraise
> - * rules.
> + * rules. As the secure boot rules includes all of the build time
> + * rules, include either one or the other set of rules, but not both.
> */
> - for (i = 0; i < ARRAY_SIZE(build_appraise_rules); i++) {
> - struct ima_rule_entry *entry;
> -
> - if (!secure_boot_entries)
> - list_add_tail(&build_appraise_rules[i].list,
> - &ima_default_rules);
> -
> - entry = kmemdup(&build_appraise_rules[i], sizeof(*entry),
> - GFP_KERNEL);
> - if (entry)
> - list_add_tail(&entry->list, &ima_policy_rules);
> - build_ima_appraise |=
> - ima_appraise_flag(build_appraise_rules[i].func);
> + build_appraise_entries = ARRAY_SIZE(build_appraise_rules);
> + if (build_appraise_entries) {
> + if (ima_use_secure_boot)
> + add_rules(build_appraise_rules, build_appraise_entries,
> + IMA_CUSTOM_POLICY);
> + else
> + add_rules(build_appraise_rules, build_appraise_entries,
> + IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
> }
>
> - for (i = 0; i < appraise_entries; i++) {
> - list_add_tail(&default_appraise_rules[i].list,
> - &ima_default_rules);
> - if (default_appraise_rules[i].func == POLICY_CHECK)
> - temp_ima_appraise |= IMA_APPRAISE_POLICY;
> - }
> + if (ima_use_appraise_tcb)
> + add_rules(default_appraise_rules,
> + ARRAY_SIZE(default_appraise_rules),
> + IMA_DEFAULT_POLICY);
>
> ima_rules = &ima_default_rules;
> ima_update_policy_flag();
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