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 */
+		err = audit_rule_change(msg_type, NETLINK_CB(skb).portid,
-	case AUDIT_LIST_RULES:
-		err = audit_receive_filter(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

@@ -1023,47 +1023,20 @@ 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)
+			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:
-		/* 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
-		 * happen if we're actually running in the context of auditctl
-		 * trying to _send_ the stuff */
-
-		dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
-		if (!dest)
-			return -ENOMEM;
-		dest->portid = portid;
-		dest->pid = task_pid_vnr(current);
-		skb_queue_head_init(&dest->q);
-
-		mutex_lock(&audit_filter_mutex);
-		audit_list_rules(portid, seq, &dest->q);
-		mutex_unlock(&audit_filter_mutex);
-
-		tsk = kthread_run(audit_send_list, dest, "audit_send_list");
-		if (IS_ERR(tsk)) {
-			skb_queue_purge(&dest->q);
-			kfree(dest);
-			err = PTR_ERR(tsk);
-		}
-		break;
 	case AUDIT_ADD_RULE:
 		entry = audit_data_to_entry(data, datasz);
 		if (IS_ERR(entry))
@@ -1090,6 +1063,44 @@ int audit_receive_filter(int type, __u32 portid, int seq, void *data,
 	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
+	 * happen if we're actually running in the context of auditctl
+	 * trying to _send_ the stuff */
+
+	dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
+	if (!dest)
+		return -ENOMEM;
+	dest->portid = portid;
+	dest->pid = task_pid_vnr(current);
+	skb_queue_head_init(&dest->q);
+
+	mutex_lock(&audit_filter_mutex);
+	audit_list_rules(portid, seq, &dest->q);
+	mutex_unlock(&audit_filter_mutex);
+
+	tsk = kthread_run(audit_send_list, dest, "audit_send_list");
+	if (IS_ERR(tsk)) {
+		skb_queue_purge(&dest->q);
+		kfree(dest);
+		err = PTR_ERR(tsk);
+	}
+
+	return err;
+}
+
 int audit_comparator(u32 left, u32 op, u32 right)
 {
 	switch (op) {