PHP / AJAX发布安全性

Question

On my website I have the following javascript/ajax code that is called when a user submits the logon form.

The login form then checks the information and passes back messages and PASS or ERROR.

On a success message I would then like the ajax to redirect to the php code again to double check for a valid logon before setting up the session, is this necessary? how would i "redirect" from within ajax whilst retaining the $_POST data?

//login form ajax
$("#login-form").submit(
function() {

  $("#FormMessages").removeClass().addClass('alert alert-info').html(
      '<img src="images/loading.gif" /> Validating....').fadeIn(500);

  $.ajax({
    url: $("#login-form").attr('action'),
    dataType: 'json',
    type: 'POST',
    data: {
      username : $('#email').val(),
      password : $('#password').val()
    },

    success: function(data){
      if (data.status == 'PASS') {
        $("#FormMessages").fadeTo(
            100,
            0.1,
            function() 
            {

              $(this).html('Logging In...').removeClass().addClass(
                  'alert alert-success').fadeTo(450, 1,
                  function() {
                    document.location = curUrl;
                  });
            });

      } else {
        $("#FormMessages").fadeTo(
            200,
            0.1,
            function() 
            {                    
                $(this).html('<h4>Error!</h4>')
                    .removeClass().addClass('alert alert-danger')
                    .fadeTo(450, 1);

              $("#FormMessages").append('<ul>');
              $(data.messages).each(function(i,obj) {
                $("#FormMessages").append(''+obj+'');

                });
              $("#FormMessages").append('');                  
            });
      }

    }
  });


  return false;
});

Thanks for reading!