audit: refactor audit_receive_msg() to clarify AUDIT_*_RULE* cases

audit_receive_msg() needlessly contained a fallthrough case that called
audit_receive_filter(), containing no common code between the cases.  Separate
them to make the logic clearer.  Refactor AUDIT_LIST_RULES, AUDIT_ADD_RULE,
AUDIT_DEL_RULE cases to create audit_rule_change(), audit_list_rules_send()
functions.  This should not functionally change the logic.
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>

include/linux/audit.h

@@ -461,8 +461,10 @@ extern int		    audit_update_lsm_rules(void);
 				/* Private API (for audit.c only) */
 extern int audit_filter_user(int type);
 extern int audit_filter_type(int type);
-extern int  audit_receive_filter(int type, __u32 portid, int seq,
+extern int audit_rule_change(int type, __u32 portid, int seq,
 				void *data, size_t datasz);
+extern int audit_list_rules_send(__u32 portid, int seq);
+
 extern int audit_enabled;
 #else /* CONFIG_AUDIT */
 static inline __printf(4, 5)

kernel/audit.c

@@ -903,11 +903,12 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 			audit_log_end(ab);
 			return -EPERM;
 		}
-		/* fallthrough */
-	case AUDIT_LIST_RULES:
-		err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid,
+		err = audit_rule_change(msg_type, NETLINK_CB(skb).portid,
 					   seq, data, nlmsg_len(nlh));
 		break;
+	case AUDIT_LIST_RULES:
+		err = audit_list_rules_send(NETLINK_CB(skb).portid, seq);
+		break;
 	case AUDIT_TRIM:
 		audit_trim_trees();
 		audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);

kernel/auditfilter.c

@@ -1023,23 +1023,57 @@ static void audit_log_rule_change(char *action, struct audit_krule *rule, int re
 }
 
 /**
- * audit_receive_filter - apply all rules to the specified message type
+ * audit_rule_change - apply all rules to the specified message type
  * @type: audit message type
  * @portid: target port id for netlink audit messages
  * @seq: netlink audit message sequence (serial) number
  * @data: payload data
  * @datasz: size of payload data
  */
-int audit_receive_filter(int type, __u32 portid, int seq, void *data,
+int audit_rule_change(int type, __u32 portid, int seq, void *data,
 			size_t datasz)
 {
-	struct task_struct *tsk;
-	struct audit_netlink_list *dest;
 	int err = 0;
 	struct audit_entry *entry;
 
 	switch (type) {
-	case AUDIT_LIST_RULES:
+	case AUDIT_ADD_RULE:
+		entry = audit_data_to_entry(data, datasz);
+		if (IS_ERR(entry))
+			return PTR_ERR(entry);
+
+		err = audit_add_rule(entry);
+		audit_log_rule_change("add rule", &entry->rule, !err);
+		if (err)
+			audit_free_rule(entry);
+		break;
+	case AUDIT_DEL_RULE:
+		entry = audit_data_to_entry(data, datasz);
+		if (IS_ERR(entry))
+			return PTR_ERR(entry);
+
+		err = audit_del_rule(entry);
+		audit_log_rule_change("remove rule", &entry->rule, !err);
+		audit_free_rule(entry);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return err;
+}
+
+/**
+ * audit_list_rules_send - list the audit rules
+ * @portid: target portid for netlink audit messages
+ * @seq: netlink audit message sequence (serial) number
+ */
+int audit_list_rules_send(__u32 portid, int seq)
+{
+	struct task_struct *tsk;
+	struct audit_netlink_list *dest;
+	int err = 0;
+
 	/* We can't just spew out the rules here because we might fill
 	 * the available socket buffer space and deadlock waiting for
 	 * auditctl to read from it... which isn't ever going to
@@ -1063,29 +1097,6 @@ int audit_receive_filter(int type, __u32 portid, int seq, void *data,
 		kfree(dest);
 		err = PTR_ERR(tsk);
 	}
-		break;
-	case AUDIT_ADD_RULE:
-		entry = audit_data_to_entry(data, datasz);
-		if (IS_ERR(entry))
-			return PTR_ERR(entry);
-
-		err = audit_add_rule(entry);
-		audit_log_rule_change("add rule", &entry->rule, !err);
-		if (err)
-			audit_free_rule(entry);
-		break;
-	case AUDIT_DEL_RULE:
-		entry = audit_data_to_entry(data, datasz);
-		if (IS_ERR(entry))
-			return PTR_ERR(entry);
-
-		err = audit_del_rule(entry);
-		audit_log_rule_change("remove rule", &entry->rule, !err);
-		audit_free_rule(entry);
-		break;
-	default:
-		return -EINVAL;
-	}
 
 	return err;
 }