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-rw-r--r--security/integrity/ima/ima_policy.c30
1 files changed, 27 insertions, 3 deletions
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 31d677f7c65..4719bbf1641 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -45,9 +45,17 @@ struct ima_measure_rule_entry {
} lsm[MAX_LSM_RULES];
};
-/* Without LSM specific knowledge, the default policy can only be
+/*
+ * Without LSM specific knowledge, the default policy can only be
* written in terms of .action, .func, .mask, .fsmagic, and .uid
*/
+
+/*
+ * The minimum rule set to allow for full TCB coverage. Measures all files
+ * opened or mmap for exec and everything read by root. Dangerous because
+ * normal users can easily run the machine out of memory simply building
+ * and running executables.
+ */
static struct ima_measure_rule_entry default_rules[] = {
{.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,.flags = IMA_FSMAGIC},
{.action = DONT_MEASURE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
@@ -59,6 +67,8 @@ static struct ima_measure_rule_entry default_rules[] = {
.flags = IMA_FUNC | IMA_MASK},
{.action = MEASURE,.func = BPRM_CHECK,.mask = MAY_EXEC,
.flags = IMA_FUNC | IMA_MASK},
+ {.action = MEASURE,.func = PATH_CHECK,.mask = MAY_READ,.uid = 0,
+ .flags = IMA_FUNC | IMA_MASK | IMA_UID},
};
static LIST_HEAD(measure_default_rules);
@@ -67,6 +77,14 @@ static struct list_head *ima_measure;
static DEFINE_MUTEX(ima_measure_mutex);
+static bool ima_use_tcb __initdata;
+static int __init default_policy_setup(char *str)
+{
+ ima_use_tcb = 1;
+ return 1;
+}
+__setup("ima_tcb", default_policy_setup);
+
/**
* ima_match_rules - determine whether an inode matches the measure rule.
* @rule: a pointer to a rule
@@ -162,9 +180,15 @@ int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask)
*/
void ima_init_policy(void)
{
- int i;
+ int i, entries;
+
+ /* if !ima_use_tcb set entries = 0 so we load NO default rules */
+ if (ima_use_tcb)
+ entries = ARRAY_SIZE(default_rules);
+ else
+ entries = 0;
- for (i = 0; i < ARRAY_SIZE(default_rules); i++)
+ for (i = 0; i < entries; i++)
list_add_tail(&default_rules[i].list, &measure_default_rules);
ima_measure = &measure_default_rules;
}