boolean isSuperUser(String userName) {
    Configuration conf      = getConf();
    String        ipAddress = HMSHandler.getIPAddress();
    ProxyUsers.refreshSuperUserGroupsConfiguration(conf);
    return (MetaStoreServerUtils.checkUserHasHostProxyPrivileges(userName, conf, ipAddress));
  }
HiveMetaStoreAuthorizer :  Do authorization checks on MetaStore Events in MetaStorePreEventListener
ql/src/java/org/apache/hadoop/hive/ql/security/authorization/plugin/metastore/HiveMetaStoreAuthorizer.java