code: func badPrefix(fpath string) error {
  	var badprefixes = []string{"/usr"}
  
  	for _, prefix := range badprefixes {
  		if fpath == prefix || strings.HasPrefix(fpath, fmt.Sprintf("%s/", prefix)) {
  			return fmt.Errorf("Relabeling content in %s is not allowed.", prefix)
  		}
  	}
  	return nil
  }
docs: // Prevent users from relabing system files