Buffer based hook functions, such as KEXEC_CMDLINE and KEY_CHECK, can
only measure. The process_buffer_measurement() function quietly ignores
all actions except measure so make this behavior clear at the time of
policy load.

The parsing of the keyrings conditional had a check to ensure that it
was only specified with measure actions but the check should be on the
hook function and not the keyrings conditional since
"appraise func=KEY_CHECK" is not a valid rule.

Fixes: b0935123a183 ("IMA: Define a new hook to measure the kexec boot command line arguments")
Fixes: 5808611cccb2 ("IMA: Add KEY_CHECK func to measure keys")
Signed-off-by: Tyler Hicks <redacted>
---
 security/integrity/ima/ima_policy.c | 36 +++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index ee5152ecd3d9..ecc234b956a2 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c

@@ -979,6 +979,39 @@ static void check_template_modsig(const struct ima_template_desc *template)
 #undef MSG
 }
 
+static bool ima_validate_rule(struct ima_rule_entry *entry)
+{
+	if (entry->action == UNKNOWN)
+		return false;
+
+	if (entry->flags & IMA_FUNC) {
+		switch (entry->func) {
+		case NONE:
+		case FILE_CHECK:
+		case MMAP_CHECK:
+		case BPRM_CHECK:
+		case CREDS_CHECK:
+		case POST_SETATTR:
+		case MODULE_CHECK:
+		case FIRMWARE_CHECK:
+		case KEXEC_KERNEL_CHECK:
+		case KEXEC_INITRAMFS_CHECK:
+		case POLICY_CHECK:
+			break;
+		case KEXEC_CMDLINE:
+		case KEY_CHECK:
+			if (entry->action & ~(MEASURE | DONT_MEASURE))
+				return false;
+
+			break;
+		default:
+			return false;
+		}
+	}
+
+	return true;
+}
+