On 11/20/20 6:30 AM, Mimi Zohar wrote:
Hi Mimi,
On Thu, 2020-11-19 at 15:26 -0800, Tushar Sugandhi wrote:
From: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
The IMA hook to measure kernel critical data, namely
ima_measure_critical_data(), could be called before a custom IMA policy
is loaded.
Define a new critical data builtin policy to allow measuring
early kernel integrity critical data before a custom IMA policy is
loaded.
Everything needing to be said seems to be included in the second
sentence. Does the first sentence add anything? "Define a new
critical data builtin policy" makes for a good Subject line.
Agreed - will update.
Add critical data to built-in IMA rules if the kernel command line
contains "ima_policy=critical_data".
The boot command line parameters are defined in Documentation/admin-
guide/kernel-parameters.txt. Please update "ima_policy".
Will do.
Signed-off-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
---
security/integrity/ima/ima_policy.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index c9e52dab0638..119604a3efa0 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -206,6 +206,10 @@ static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
.flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
};
+static struct ima_rule_entry critical_data_rules[] __ro_after_init = {
+ {.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC},
+};
+
/* An array of architecture specific rules */
static struct ima_rule_entry *arch_policy_entry __ro_after_init;
@@ -228,6 +232,7 @@ __setup("ima_tcb", default_measure_policy_setup);
static bool ima_use_appraise_tcb __initdata;
static bool ima_use_secure_boot __initdata;
+static bool ima_use_critical_data __ro_after_init;
Unlike ima_fail_unverifiable_sigs, ima_use_critical_data is only used
during __init. Please change "__ro_after_init" to "__initdata". (The
critical data policy itself is defined properly as __ro_after_init.)
Will do.
static bool ima_fail_unverifiable_sigs __ro_after_init;
static int __init policy_setup(char *str)
{
@@ -242,6 +247,8 @@ static int __init policy_setup(char *str)
ima_use_appraise_tcb = true;
else if (strcmp(p, "secure_boot") == 0)
ima_use_secure_boot = true;
+ else if (strcmp(p, "critical_data") == 0)
+ ima_use_critical_data = true;
else if (strcmp(p, "fail_securely") == 0)
ima_fail_unverifiable_sigs = true;
else
@@ -875,6 +882,11 @@ void __init ima_init_policy(void)
ARRAY_SIZE(default_appraise_rules),
IMA_DEFAULT_POLICY);
+ if (ima_use_critical_data)
+ add_rules(critical_data_rules,
+ ARRAY_SIZE(critical_data_rules),
+ IMA_DEFAULT_POLICY);
+
ima_update_policy_flag();
}
thanks,
-lakshmi
