bug symfony#59146 [Security] Use the session only if it is started when using SameOriginCsrfTokenManager (Thibault G)

This PR was merged into the 7.2 branch.

Discussion
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[Security] Use the session only if it is started when using `SameOriginCsrfTokenManager`

| Q             | A
| ------------- | ---
| Branch?       | 7.2
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        | Fix symfony#59092
| License       | MIT

If I understand well, the `SameOriginCsrfTokenManager` has been created to provide a stateless way of creating CSRF tokens and therefore allow pages with CSRF tokens to be cached.

When using `Symfony\Component\Security\Csrf\SameOriginCsrfTokenManager`, I think an additionnal check must be done to ensure that the session is started in addition to verifying that it exists. If not, the CSRF strategy used will be persisted everytime in the session and the stateless check (used with the `#[Route]` attribute parameter) will therefore never pass.

Commits
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1327e38 [Security] Use the session only if it is started when using `SameOriginCsrfTokenManager`

Author: fabpot

src/Symfony/Component/Security/Csrf/SameOriginCsrfTokenManager.php

@@ -207,9 +207,17 @@ public function clearCookies(Request $request, Response $response): void
 
     public function persistStrategy(Request $request): void
     {
-        if ($request->hasSession(true) && $request->attributes->has($this->cookieName)) {
-            $request->getSession()->set($this->cookieName, $request->attributes->get($this->cookieName));
+        if (!$request->attributes->has($this->cookieName)
+            || !$request->hasSession(true)
+            || !($session = $request->getSession())->isStarted()
+        ) {
+            return;
         }
+
+        $usageIndexValue = $session instanceof Session ? $usageIndexReference = &$session->getUsageIndex() : 0;
+        $usageIndexReference = \PHP_INT_MIN;
+        $session->set($this->cookieName, $request->attributes->get($this->cookieName));
+        $usageIndexReference = $usageIndexValue;
     }
 
     public function onKernelResponse(ResponseEvent $event): void

src/Symfony/Component/Security/Csrf/Tests/SameOriginCsrfTokenManagerTest.php

@@ -221,9 +221,11 @@ public function testClearCookies()
         $this->assertTrue($response->headers->has('Set-Cookie'));
     }
 
-    public function testPersistStrategyWithSession()
+    public function testPersistStrategyWithStartedSession()
     {
         $session = $this->createMock(Session::class);
+        $session->method('isStarted')->willReturn(true);
+
         $request = new Request();
         $request->setSession($session);
         $request->attributes->set('csrf-token', 2 << 8);
@@ -233,6 +235,19 @@ public function testPersistStrategyWithSession()
         $this->csrfTokenManager->persistStrategy($request);
     }
 
+    public function testPersistStrategyWithSessionNotStarted()
+    {
+        $session = $this->createMock(Session::class);
+
+        $request = new Request();
+        $request->setSession($session);
+        $request->attributes->set('csrf-token', 2 << 8);
+
+        $session->expects($this->never())->method('set');
+
+        $this->csrfTokenManager->persistStrategy($request);
+    }
+
     public function testOnKernelResponse()
     {
         $request = new Request([], [], ['csrf-token' => 2], ['csrf-token_test' => 'csrf-token']);