New Data Voter Article (continuation)

cookbook/map.rst.inc

@@ -127,6 +127,7 @@
   * :doc:`/cookbook/security/remember_me`
   * :doc:`/cookbook/security/impersonating_user`
   * :doc:`/cookbook/security/voters`
+  * :doc:`/cookbook/security/voters_data_permission`
   * :doc:`/cookbook/security/acl`
   * :doc:`/cookbook/security/acl_advanced`
   * :doc:`/cookbook/security/force_https`

cookbook/security/acl.rst

@@ -14,7 +14,7 @@ the ACL system comes in.
     Using ACL's isn't trivial, and for simpler use cases, it may be overkill.
     If your permission logic could be described by just writing some code (e.g.
     to check if a Blog is owned by the current User), then consider using
-    :doc:`voters </cookbook/security/voters>`. A voter is passed the object
+    :doc:`voters </cookbook/security/voters_data_permission>`. A voter is passed the object
     being voted on, which you can use to make complex decisions and effectively
     implement your own ACL. Enforcing authorization (e.g. the ``isGranted``
     part) will look similar to what you see in this entry, but your voter

cookbook/security/index.rst

@@ -8,6 +8,7 @@ Security
     remember_me
     impersonating_user
     voters
+    voters_data_permission
     acl
     acl_advanced
     force_https

cookbook/security/voter_interface.rst.inc

@@ -0,0 +1,24 @@
+.. code-block:: php
+
+    interface VoterInterface
+    {
+        public function supportsAttribute($attribute);
+        public function supportsClass($class);
+        public function vote(TokenInterface $token, $post, array $attributes);
+    }
+
+The :method:`Symfony\\Component\\Security\\Core\\Authorization\\Voter\\VoterInterface::supportsAttribute`
+method is used to check if the voter supports the given user attribute (i.e:
+a role like ``ROLE_USER``, an ACL ``EDIT``, etc.).
+
+The :method:`Symfony\\Component\\Security\\Core\\Authorization\\Voter\\VoterInterface::supportsClass`
+method is used to check if the voter supports the class of the object whose
+access is being checked.
+
+The :method:`Symfony\\Component\\Security\\Core\\Authorization\\Voter\\VoterInterface::vote`
+method must implement the business logic that verifies whether or not the
+user has access. This method must return one of the following values:
+
+* ``VoterInterface::ACCESS_GRANTED``: The authorization will be granted by this voter;
+* ``VoterInterface::ACCESS_ABSTAIN``: The voter cannot decide if authorization should be granted;
+* ``VoterInterface::ACCESS_DENIED``: The authorization will be denied by this voter.

cookbook/security/voters.rst

@@ -21,28 +21,7 @@ A custom voter must implement
 :class:`Symfony\\Component\\Security\\Core\\Authorization\\Voter\\VoterInterface`,
 which requires the following three methods:
 
-.. code-block:: php
-
-    interface VoterInterface
-    {
-        public function supportsAttribute($attribute);
-        public function supportsClass($class);
-        public function vote(TokenInterface $token, $object, array $attributes);
-    }
-
-The ``supportsAttribute()`` method is used to check if the voter supports
-the given user attribute (i.e: a role, an ACL, etc.).
-
-The ``supportsClass()`` method is used to check if the voter supports the
-class of the object whose access is being checked (doesn't apply to this entry).
-
-The ``vote()`` method must implement the business logic that verifies whether
-or not the user is granted access. This method must return one of the following
-values:
-
-* ``VoterInterface::ACCESS_GRANTED``: The authorization will be granted by this voter;
-* ``VoterInterface::ACCESS_ABSTAIN``: The voter cannot decide if authorization should be granted;
-* ``VoterInterface::ACCESS_DENIED``: The authorization will be denied by this voter.
+.. include:: /cookbook/security/voter_interface.rst.inc
 
 In this example, you'll check if the user's IP address matches against a list of
 blacklisted addresses and "something" will be the application. If the user's IP is blacklisted, you'll return

cookbook/security/voters_data_permission.rst

@@ -0,0 +1,223 @@
+.. index::
+   single: Security; Data Permission Voters
+
+How to Use Voters to Check User Permissions
+===========================================
+
+In Symfony2 you can check the permission to access data by using the
+:doc:`ACL module </cookbook/security/acl>`, which is a bit overwhelming
+for many applications. A much easier solution is to work with custom voters,
+which are like simple conditional statements.
+
+.. seealso::
+
+    Voters can also be used in other ways, like, for example, blacklisting IP
+    addresses from the entire application: ":doc:`/cookbook/security/voters`".
+
+.. tip::
+
+    Take a look at the
+    :doc:`authorization </components/security/authorization>`
+    chapter for an even deeper understanding on voters.
+
+How Symfony Uses Voters
+-----------------------
+
+In order to use voters, you have to understand how Symfony works with them.
+All voters are called each time you use the ``isGranted()`` method on Symfony's
+security context (i.e. the ``security.context`` service). Each decides if
+the current user should have access to some resource.
+
+Ultimately, Symfony uses one of three different approaches on what to do
+with the feedback from all voters: affirmative, consensus and unanimous.
+
+For more information take a look at ":ref:`the section about access decision managers <components-security-access-decision-manager>`".
+
+The Voter Interface
+-------------------
+
+A custom voter must implement
+:class:`Symfony\\Component\\Security\\Core\\Authorization\\Voter\\VoterInterface`,
+which has this structure:
+
+.. include:: /cookbook/security/voter_interface.rst.inc
+
+In this example, the voter will check if the user has access to a specific
+object according to your custom conditions (e.g. they must be the owner of
+the object). If the condition fails, you'll return
+``VoterInterface::ACCESS_DENIED``, otherwise you'll return
+``VoterInterface::ACCESS_GRANTED``. In case the responsibility for this decision
+does not belong to this voter, it will return ``VoterInterface::ACCESS_ABSTAIN``.
+
+Creating the Custom Voter
+-------------------------
+
+The goal is to create a voter that checks to see if a user has access to
+view or edit a particular object. Here's an example implementation:
+
+    // src/Acme/DemoBundle/Security/Authorization/Voter/PostVoter.php
+    namespace Acme\DemoBundle\Security\Authorization\Voter;
+
+    use Symfony\Component\Security\Core\Exception\InvalidArgumentException;
+    use Symfony\Component\DependencyInjection\ContainerInterface;
+    use Symfony\Component\Security\Core\Authorization\Voter\VoterInterface;
+    use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
+    use Symfony\Component\Security\Core\User\UserInterface;
+    use Acme\DemoBundle\Entity\Post;
+
+    class PostVoter implements VoterInterface
+    {
+        const VIEW = 'view';
+        const EDIT = 'edit';
+
+        public function supportsAttribute($attribute)
+        {
+            return in_array($attribute, array(
+                self::VIEW,
+                self::EDIT,
+            ));
+        }
+
+        public function supportsClass($obj)
+        {
+            return $obj instanceof Post;
+        }
+
+        /**
+         * @var \Acme\DemoBundle\Entity\Post $post
+         */
+        public function vote(TokenInterface $token, $post, array $attributes)
+        {
+            // check if class of this object is supported by this voter
+            if (!$this->supportsClass($post)) {
+                return VoterInterface::ACCESS_ABSTAIN;
+            }
+
+            // check if voter is used correct, only allow one attribute for a check
+            // this isn't a requirement, it's just the way we want our voter to work
+            if(1 !== count($attributes)) {
+                throw new InvalidArgumentException(
+                    'Only one attribute is allowed for VIEW or EDIT'
+                );
+            }
+
+            // set the attribute to check against
+            $attribute = $attributes[0];
+
+            // get current logged in user
+            $user = $token->getUser();
+
+            // check if the given attribute is covered by this voter
+            if (!$this->supportsAttribute($attribute)) {
+                return VoterInterface::ACCESS_ABSTAIN;
+            }
+
+            // make sure there is a user object (i.e. that the user is logged in)
+            if (!$user instanceof UserInterface) {
+                return VoterInterface::ACCESS_DENIED;
+            }
+
+            switch($attribute) {
+                case 'view':
+                    // the data object could have for example a method isPrivate()
+                    // which checks the Boolean attribute $private
+                    if (!$post->isPrivate()) {
+                        return VoterInterface::ACCESS_GRANTED;
+                    }
+                    break;
+
+                case 'edit':
+                    // we assume that our data object has a method getOwner() to
+                    // get the current owner user entity for this data object
+                    if ($user->getId() === $post->getOwner()->getId()) {
+                        return VoterInterface::ACCESS_GRANTED;
+                    }
+                    break;
+            }
+        }
+    }
+
+That's it! The voter is done. The next step is to inject the voter into
+the security layer.
+
+Declaring the Voter as a Service
+--------------------------------
+
+To inject the voter into the security layer, you must declare it as a service
+and tag it with ``security.voter``:
+
+.. configuration-block::
+
+    .. code-block:: yaml
+
+        # src/Acme/DemoBundle/Resources/config/services.yml
+        services:
+            security.access.post_voter:
+                class:      Acme\DemoBundle\Security\Authorization\Voter\PostVoter
+                public:     false
+                tags:
+                   - { name: security.voter }
+
+    .. code-block:: xml
+
+        <!-- src/Acme/DemoBundle/Resources/config/services.xml -->
+        <?xml version="1.0" encoding="UTF-8" ?>
+        <container xmlns="http://symfony.com/schema/dic/services"
+            xsi:schemaLocation="http://symfony.com/schema/dic/services
+                http://symfony.com/schema/dic/services/services-1.0.xsd">
+            <services>
+                <service id="security.access.post_document_voter"
+                    class="Acme\DemoBundle\Security\Authorization\Voter\PostVoter"
+                    public="false">
+                    <tag name="security.voter" />
+                </service>
+            </services>
+        </container>
+
+    .. code-block:: php
+
+        // src/Acme/DemoBundle/Resources/config/services.php
+        $container
+            ->register(
+                    'security.access.post_document_voter',
+                    'Acme\DemoBundle\Security\Authorization\Voter\PostVoter'
+            )
+            ->addTag('security.voter')
+        ;
+
+How to Use the Voter in a Controller
+------------------------------------
+
+The registered voter will then always be asked as soon as the method ``isGranted()``
+from the security context is called.
+
+.. code-block:: php
+
+    // src/Acme/DemoBundle/Controller/PostController.php
+    namespace Acme\DemoBundle\Controller;
+
+    use Symfony\Bundle\FrameworkBundle\Controller\Controller;
+    use Symfony\Component\HttpFoundation\Response;
+    use Symfony\Component\Security\Core\Exception\AccessDeniedException;
+
+    class PostController extends Controller
+    {
+        public function showAction()
+        {
+            // get a Post instance
+            $post = ...;
+
+            // keep in mind, this will call all registered security voters
+            if (false === $this->get('security.context')->isGranted('view', $post)) {
+                throw new AccessDeniedException('Unauthorised access!');
+            }
+
+            $product = $this->getDoctrine()
+                ->getRepository('AcmeStoreBundle:Post')
+                ->find($id);
+
+            return new Response('<h1>'.$post->getName().'</h1>');
+        }
+    }
+
+It's that easy!