ima: Do not audit if CONFIG_INTEGRITY_AUDIT is not set

If Integrity is not auditing, IMA shouldn't audit, either.
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

security/integrity/ima/Kconfig

@@ -12,6 +12,7 @@ config IMA
 	select TCG_TIS if TCG_TPM && X86
 	select TCG_CRB if TCG_TPM && ACPI
 	select TCG_IBMVTPM if TCG_TPM && PPC_PSERIES
+	select INTEGRITY_AUDIT if AUDIT
 	help
 	  The Trusted Computing Group(TCG) runtime Integrity
 	  Measurement Architecture(IMA) maintains a list of hash

security/integrity/ima/ima_policy.c

@@ -657,6 +657,9 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
 			      bool (*rule_operator)(kuid_t, kuid_t))
 {
+	if (!ab)
+		return;
+
 	if (rule_operator == &uid_gt)
 		audit_log_format(ab, "%s>", key);
 	else if (rule_operator == &uid_lt)
@@ -678,7 +681,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 	bool uid_token;
 	int result = 0;
 
-	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
+	ab = integrity_audit_log_start(NULL, GFP_KERNEL,
+				       AUDIT_INTEGRITY_RULE);
 
 	entry->uid = INVALID_UID;
 	entry->fowner = INVALID_UID;

security/integrity/integrity.h

@@ -15,6 +15,7 @@
 #include <linux/integrity.h>
 #include <crypto/sha.h>
 #include <linux/key.h>
+#include <linux/audit.h>
 
 /* iint action cache flags */
 #define IMA_MEASURE		0x00000001
@@ -199,6 +200,13 @@ static inline void evm_load_x509(void)
 void integrity_audit_msg(int audit_msgno, struct inode *inode,
 			 const unsigned char *fname, const char *op,
 			 const char *cause, int result, int info);
+
+static inline struct audit_buffer *
+integrity_audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, int type)
+{
+	return audit_log_start(ctx, gfp_mask, type);
+}
+
 #else
 static inline void integrity_audit_msg(int audit_msgno, struct inode *inode,
 				       const unsigned char *fname,
@@ -206,4 +214,11 @@ static inline void integrity_audit_msg(int audit_msgno, struct inode *inode,
 				       int result, int info)
 {
 }
+
+static inline struct audit_buffer *
+integrity_audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, int type)
+{
+	return NULL;
+}
+
 #endif