test(ex/skate_web/auth_controller): test for csrf failure (#2586)

* test(ex/skate_web/auth_controller): test for csrf failure

* feat(ex/skate_web/auth_controller): redirect csrf issues to login

* test:feat(ex/skate_web/auth_controller): test that second failure returns existing behaviour

* feat(ex/skate_web/auth_controller): only redirect to login on first CSRF error

* cleanup(ex/skate_web/auth_controller): delete "retry" session variable on second try

* cleanup(ex/skate_web/auth_controller): replace failure with module attribute `@ueberauth_csrf_failure`

lib/skate_web/controllers/auth_controller.ex

@@ -70,6 +70,34 @@ defmodule SkateWeb.AuthController do
     |> redirect(to: ~p"/")
   end
 
+  def callback(
+        %{
+          assigns: %{
+            ueberauth_failure:
+              %Ueberauth.Failure{
+                provider: :keycloak,
+                errors: [%Ueberauth.Failure.Error{message_key: "csrf_attack"}]
+              } = auth_struct
+          }
+        } = conn,
+        _params
+      ) do
+    Logger.error(
+      "#{__MODULE__} keycloak callback csrf ueberauth_failure struct=#{Kernel.inspect(auth_struct)}"
+    )
+
+    if get_session(conn, :keycloak_csrf_retry) == 1 do
+      conn
+      |> delete_session(:keycloak_csrf_retry)
+      |> send_resp(:unauthorized, "unauthenticated")
+    else
+      conn
+      |> put_session(:keycloak_csrf_retry, 1)
+      |> Guardian.Plug.sign_out(AuthManager, [])
+      |> redirect(to: ~p"/auth/keycloak")
+    end
+  end
+
   def callback(
         %{assigns: %{ueberauth_failure: %{provider: :keycloak} = auth_struct}} = conn,
         _params

test/skate_web/controllers/auth_controller_test.exs

@@ -134,6 +134,32 @@ defmodule SkateWeb.AuthControllerTest do
 
       assert response(conn, :unauthorized) == "unauthenticated"
     end
+
+    @ueberauth_csrf_failure %Ueberauth.Failure{
+      provider: :keycloak,
+      errors: [%Ueberauth.Failure.Error{message_key: "csrf_attack"}]
+    }
+
+    test "retries login on first ueberauth CSRF failure", %{conn: conn} do
+      conn =
+        conn
+        |> init_test_session(%{username: "test_username"})
+        |> assign(:ueberauth_failure, @ueberauth_csrf_failure)
+        |> get(~p"/auth/keycloak/callback")
+
+      assert redirected_to(conn, :found) == ~p"/auth/keycloak"
+    end
+
+    test "when CSRF error is encountered again, returns unauthenticated", %{conn: conn} do
+      conn =
+        conn
+        |> init_test_session(%{username: "test_username"})
+        |> assign(:ueberauth_failure, @ueberauth_csrf_failure)
+        |> put_session(:keycloak_csrf_retry, 1)
+        |> get(~p"/auth/keycloak/callback")
+
+      assert response(conn, :unauthorized) == "unauthenticated"
+    end
   end
 
   describe "GET /auth/keycloak/logout" do