ima: Fail rule parsing when asymmetric key measurement isn't supportable

Measuring keys is currently only supported for asymmetric keys. In the
future, this might change.

For now, the "func=KEY_CHECK" and "keyrings=" options are only
appropriate when CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS is enabled. Make
this clear at policy load so that IMA policy authors don't assume that
these policy language constructs are supported.

Fixes: 2b60c0ecedf8 ("IMA: Read keyrings= option from the IMA policy")
Fixes: 5808611cccb2 ("IMA: Add KEY_CHECK func to measure keys")
Suggested-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Reviewed-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index ea224f0..fe1df37 100644 (file)
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1233,7 +1233,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
                                entry->func = POLICY_CHECK;
                        else if (strcmp(args[0].from, "KEXEC_CMDLINE") == 0)
                                entry->func = KEXEC_CMDLINE;
-                       else if (strcmp(args[0].from, "KEY_CHECK") == 0)
+                       else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) &&
+                                strcmp(args[0].from, "KEY_CHECK") == 0)
                                entry->func = KEY_CHECK;
                        else
                                result = -EINVAL;
@@ -1290,7 +1291,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
                case Opt_keyrings:
                        ima_log_string(ab, "keyrings", args[0].from);
 
-                       if (entry->keyrings) {
+                       if (!IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) ||
+                           entry->keyrings) {
                                result = -EINVAL;
                                break;
                        }