[PATCH v2 3/6] ima: refactor ima_init_policy()

Nayna Jain
2018-09-14T08:00:02Z

This patch removes the code duplication in ima_init_policy() by defining
a new function named add_rules().

Signed-off-by: Nayna Jain <nayna@linux.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..b58906a05736 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();
--
2.13.6