How symfony2 know user was logged in

I have Bundle like. My idea is: all users must be login before access

app_dev.php/app/
app_dev.php/home/

or app_dev.php/home/show

AppBundle
   Controller
       LoginController.php
           indexAction() {
               echo "you can access right now";
           }
           loginAction() {
               $session = $this->getRequest()->getSession();
               if ($session->has('login')) {
                   //redirect to home/index
               }else {
                   //render login form
               }
           }
           checkAction(Request $request) {
               if($request->getMethod()=='POST') {
                    // check user input (username && password) in database
                    if (ok){
                         $session->set('login', 'true');
                         //redirect to home/index
                    }
                    else {
                         //redirect to login/index
                    }
               }else {
                    //redirect to login/index
               }
           }
           logoutAction() {
               //remove login session
               // redirect to login/index
           }
       HomeController.php
               indexAction() {
                   echo "page1";
               }
               showAction() {
                   echo "page2";
              }

My security.yml like

security:
   firewalls:
       # the login page has to be accessible for everybody
       app_login:
         pattern:  ^/app/login$
            anonymous: ~
            security: false

        secured_area:
            pattern:    ^/app
            form_login:
                check_path: /app/check
                login_path: /app/login
            logout:
                path: /app/logout
                target: /app

My routing.yml like

app_index:
    path:     /
    defaults: { _controller: ExAppBundle:Login:index }
app_login:
    path:     /login
    defaults: { _controller: ExAppBundle:Login:login }
app_check:
    path:     /check
    defaults: { _controller: ExAppBundle:Login:check }

app_logout:
    path:     /logout
    defaults: { _controller: ExAppBundle:Login:logout }

app_home_show:
    path:     /home/show
    defaults: { _controller: ExAppBundle:Home:show }

app_home_index:
    path:     /home
    defaults: { _controller: ExAppBundle:Home:index }

But that redirect to login form always. How talk to symfony know user has logged in. Thanks!