configuring-security.asciidoc

title	order	layout
Configuring Security for TypeScript Views	80	page

Configuring Security for TypeScript Views

When developing server-side views, endpoint access control is done by using regular java approaches: servlet-container based security, third party libraries, or session based solutions.

This article describes all the pieces needed for securing client centric applications.

How to secure server-side endpoints

The first step is to configure authorization of each endpoint that the application exposes.

Default security options

Consider the basic Vaadin endpoint defined in the following class:

CounterEndpoint.java

@Endpoint
public class CounterEndpoint {
    public int addOne(int number) {
        return number + 1;
    }
}

Vaadin access control features is enabled by default for any endpoint method: if not specified in Java code explicitly, before invoking an endpoint method, the presence of Principal object in the the request is required. The HttpServletRequest#getUserPrincipal() Java API is used for the check.

At this point, the servlet container or the application needs to be configured appropriately to handle user authentication. This is described in the Adding a Login Form with Spring Security and Configuring Servlet-Container Authentication articles.

Other security options

In order to change the default behavior, a security Java annotation should either be placed on the endpoint class or on the endpoint method. There are the following annotations:

• @PermitAll Same as no annotations, allows any authenticated user to call a method via the request.

• @RolesAllowed Grants access to users having the roles specified in the annotation value. Roles are covered in the next section.

• @DenyAll Disallows to call the method via the request by anyone.

• @AnonymousAllowed Permits anyone to call the method via the request without the authorization.

A security annotation that is placed on a class is applied to any public method of this class that has no security annotations. If the method has security annotations, any class-level annotation is discarded and only method ones are applied.

If there are multiple annotations specified on some entity, the following rules are applied:

• DenyAll overrides other annotations

• AnonymousAllowed overrides RolesAllowed and PermitAll

• RolesAllowed overrides PermitAll

Example:

MyEndpoint.java

@Endpoint
@DenyAll
public class MyEndpoint {

  public void deniedMethod() {
    // Not possible to call by any request due to class-level annotation
  }

  @AnonymousAllowed
  public void anonymousMethod() {
    // Possible to call by any request (even without
    // authorization) since method level annotation
    // overrides class-level one
  }

  @PermitAll
  public void permittedToAllMethod() {
    // Permitted to all authenticated users, same as if
    // there were no security annotations on the class
    // and the methods.
    // Since there's a `@DenyAll` annotation is on the
    // class, we specify this one on a method to override
    // the class one.
  }

  @RolesAllowed("ROLE_ADMIN")
  public void permittedToRoleMethod() {
    // Permited to all authenticated users belonging
    // to the ROLE_ADMIN
  }
}

Defining user permissions

As mentioned in the previous section, every user can have roles and may affect his ability to access some endpoint methods. This section explains how to specify those for each user.

Vaadin endpoints checks the existence of roles by using the HttpServletRequest#isUserInRole(String) Java API.

Once the servlet container has been configured to handle user authentication, when the server receives a request for the secured endpoint, user and its roles are checked, and if everything is alright, the method is executed.

Accessing user information in an endpoint method

When access to the UserPrincipal is required in an endpoint, call the VaadinRequest.getCurrent() method to access the HttpServletRequest API.

EchoEndpoint.java

@Endpoint
public class EchoEndpoint {
    public String saySomething(String message) {
        return VaadinRequest.getCurrent().getUserPrincipal().getName() + " says: " + message;
    }
}

frontend/index.ts

import * as endpoint from './generated/EchoEndpoint';

endpoint
    .saySomething("It's snowing in Turku")
    .then(response => console.log(response));

Checking authentication in client side

Please read the Checking Authentication article if in the client side it is needed to know whether a user is authenticated.

CSRF protection of Vaadin endpoints

Vaadin endpoints are protected from CSRF attacks using the same approach with the rest of Vaadin. See the Cross-Site Request Forgery section in the security guide for more details.