Simple Acl controlled Application

In this tutorial you will create a simple application with Authentication and Access Control Lists. This tutorial assumes you have read the Blog tutorial, and you are familiar with Code Generation with Bake. You should have some experience with CakePHP, and be familiar with MVC concepts. This tutorial is a brief introduction to the `AuthComponent <http://api.cakephp.org/class/auth-component>`_ and `AclComponent <http://api.cakephp.org/class/acl-component>`_.

What you will need

  1. A running web server. We’re going to assume you’re using Apache, though the instructions for using other servers should be very similar. We might have to play a little with the server configuration, but most folks can get Cake up and running without any configuration at all.
  2. Basic PHP knowledge. The more object-oriented programming you’ve done, the better: but fear not if you’re a procedural fan.

Preparing our Application

First, let’s get a copy of fresh Cake code.

To get a fresh download, visit the CakePHP project at Cakeforge: http://cakeforge.org/projects/cakephp/ and download the stable release. For this tutorial you need 1.2.x.x

You can also checkout/export a fresh copy of our trunk code at: https://svn.cakephp.org/repo/trunk/cake/1.2.x.x/

Once you’ve got a fresh copy of cake setup your database.php config file, and change the value of Security.salt in your app/config/core.php. From there we will build a simple database schema to build our application on. Execute the following SQL statements into your database.

CREATE TABLE users (
    id INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(255) NOT NULL UNIQUE,
    password CHAR(40) NOT NULL,
    group_id INT(11) NOT NULL,
    created DATETIME,
    modified DATETIME
);


CREATE TABLE groups (
    id INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    created DATETIME,
    modified DATETIME
);


CREATE TABLE posts (
    id INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
    user_id INT(11) NOT NULL,
    title VARCHAR(255) NOT NULL,
    body TEXT,
    created DATETIME,
    modified DATETIME
);

CREATE TABLE widgets (
    id INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    part_no VARCHAR(12),
    quantity INT(11)
);

These are the tables we will be using to build the rest of our application. Once we have the table structure in the database we can start cooking. Use Code Generation with Bake to quickly create your models, controllers, and views.

To use cake bake, call “cake bake all” and this will list the 4 tables you inserted into mySQL. Select “1 (Group).”, and follow the prompts. Repeat for the other 3 tables, and this will have generated the 4 controllers, models and your views for you.

Avoid using Scaffold here. The generation of the ACOs will be seriously affected if you bake the controllers with the Scaffold feature.

While baking the Models cake will automagically detect the associations between your Models (or relations between your tables). Let cake supply the correct hasMany and belongsTo associations. If you are prompted to pick hasOne or hasMany, generally speaking you’ll need a hasMany (only) relationships for this tutorial.

Leave out admin routing for now, this is a complicated enough subject without them. Also be sure not to add either the Acl or Auth Components to any of your controllers as you are baking them. We’ll be doing that soon enough. You should now have models, controllers, and baked views for your users, groups, posts and widgets.

Preparing to Add Auth

We now have a functioning CRUD application. Bake should have setup all the relations we need, if not add them in now. There are a few other pieces that need to be added before we can add the Auth and Acl components. First add a login and logout action to your UsersController.

function login() {
    //Auth Magic
}

function logout() {
    //Leave empty for now.
}

Then create the following view file for login at app/views/users/login.ctp:

<?php
$session->flash('auth');
echo $form->create('User', array('action' => 'login'));
echo $form->inputs(array(
    'legend' => __('Login', true),
    'username',
    'password'
));
echo $form->end('Login');
?>

We don’t need to worry about adding anything to hash passwords, as AuthComponent will do this for us automatically when creating/editing users, and when they login, once configured properly. Furthermore, if you hash incoming passwords manually AuthComponent will not be able to log you in at all. As it will hash them again, and they will not match.

Next we need to make some modifications to AppController. If you don’t have /app/app_controller.php, create it. Note that this goes in /app/, not /app/controllers/. Since we want our entire site controlled with Auth and Acl, we will set them up in AppController.

<?php
class AppController extends Controller {
    var $components = array('Acl', 'Session', 'Auth');

    function beforeFilter() {
        //Configure AuthComponent
        $this->Auth->authorize = 'actions';
        $this->Auth->loginAction = array('controller' => 'users', 'action' => 'login');
        $this->Auth->logoutRedirect = array('controller' => 'users', 'action' => 'login');
        $this->Auth->loginRedirect = array('controller' => 'posts', 'action' => 'add');
    }
}
?>

Before we set up the ACL at all we will need to add some users and groups. With AuthComponent in use we will not be able to access any of our actions, as we are not logged in. We will now add some exceptions so AuthComponent will allow us to create some groups and users. In both your GroupsController and your UsersController Add the following.

function beforeFilter() {
    parent::beforeFilter();
    $this->Auth->allow('*');
}

These statements tell AuthComponent to allow public access to all actions. This is only temporary and will be removed once we get a few users and groups into our database. Don’t add any users or groups just yet though.

Initialize the Db Acl tables

Before we create any users or groups we will want to connect them to the Acl. However, we do not at this time have any Acl tables and if you try to view any pages right now, you will get a missing table error (“Error: Database table acos for model Aco was not found.”). To remove these errors we need to run a schema file. In a shell run the following:

cake schema create DbAcl

This schema will prompt you to drop and create the tables. Say yes to dropping and creating the tables.

If you don’t have shell access, or are having trouble using the console, you can run the sql file found in /path/to/app/config/sql/db_acl.sql.

With the controllers setup for data entry, and the Acl tables initialized we are ready to go right? Not entirely, we still have a bit of work to do in the user and group models. Namely, making them auto-magically attach to the Acl.

Acts As a Requester

For Auth and Acl to work properly we need to associate our users and groups to rows in the Acl tables. In order to do this we will use the AclBehavior. The AclBehavior allows for the automagic connection of models with the Acl tables. Its use requires an implementation of parentNode() on your model. In our User model we will add the following.

var $name = 'User';
var $belongsTo = array('Group');
var $actsAs = array('Acl' => 'requester');

function parentNode() {
    if (!$this->id && empty($this->data)) {
        return null;
    }
    $data = $this->data;
    if (empty($this->data)) {
        $data = $this->read();
    }
    if (empty($data['User']['group_id'])) {
        return null;
    } else {
        return array('Group' => array('id' => $data['User']['group_id']));
    }
}

Then in our Group Model Add the following:

var $actsAs = array('Acl' => array('type' => 'requester'));

function parentNode() {
    return null;
}

What this does, is tie the Group and User models to the Acl, and tell CakePHP that every-time you make a User or Group you want an entry on the aros table as well. This makes Acl management a piece of cake as your AROs become transparently tied to your users and groups tables. So anytime you create or delete a user/group the Aro table is updated.

Our controllers and models are now prepped for adding some initial data, and our Group and User models are bound to the Acl table. So add some groups and users using the baked forms by browsing to http://example.com/groups/add and http://example.com/users/add. I made the following groups:

  • administrators
  • managers
  • users

I also created a user in each group so I had a user of each different access group to test with later. Write everything down or use easy passwords so you don’t forget. If you do a SELECT * FROM aros; from a mysql prompt you should get something like the following:

+----+-----------+-------+-------------+-------+------+------+
| id | parent_id | model | foreign_key | alias | lft  | rght |
+----+-----------+-------+-------------+-------+------+------+
|  1 |      NULL | Group |           1 | NULL  |    1 |    4 |
|  2 |      NULL | Group |           2 | NULL  |    5 |    8 |
|  3 |      NULL | Group |           3 | NULL  |    9 |   12 |
|  4 |         1 | User  |           1 | NULL  |    2 |    3 |
|  5 |         2 | User  |           2 | NULL  |    6 |    7 |
|  6 |         3 | User  |           3 | NULL  |   10 |   11 |
+----+-----------+-------+-------------+-------+------+------+
6 rows in set (0.00 sec)

This shows us that we have 3 groups and 3 users. The users are nested inside the groups, which means we can set permissions on a per-group or per-user basis.

When modifying a user, you must manually update the ARO. This code should be executed wherever you’re updating the user information:

// Check if their permission group is changing
$oldgroupid = $this->User->field('group_id');
if ($oldgroupid !== $this->data['User']['group_id']) {
    $aro =& $this->Acl->Aro;
    $user = $aro->findByForeignKeyAndModel($this->data['User']['id'], 'User');
    $group = $aro->findByForeignKeyAndModel($this->data['User']['group_id'], 'Group');

    // Save to ARO table
    $aro->id = $user['Aro']['id'];
    $aro->save(array('parent_id' => $group['Aro']['id']));
}

An alternative to the above Aro update after group_id is changed, is to add the below to your User model. Then you don’t have to worry about duplicate code.

/**
 * After save callback
 *
 * Update the aro for the user.
 *
 * @access public
 * @return void
 */
function afterSave($created) {
        if (!$created) {
            $parent = $this->parentNode();
            $parent = $this->node($parent);
            $node = $this->node();
            $aro = $node[0];
            $aro['Aro']['parent_id'] = $parent[0]['Aro']['id'];
            $this->Aro->save($aro);
        }
}

Creating ACOs

Now that we have our users and groups (aros), we can begin inputting our existing controllers into the Acl and setting permissions for our groups and users, as well as enabling login / logout.

Our AROs are automatically creating themselves when new users and groups are created. What about a way to auto-generate ACOs from our controllers and their actions? Well unfortunately there is no magic way in CakePHP’s core to accomplish this. The core classes offer a few ways to manually create ACO’s though. You can create ACO objects from the Acl shell or You can use the AclComponent. Creating Acos from the shell looks like:

cake acl create aco root controllers

While using the AclComponent would look like:

$this->Acl->Aco->create(array('parent_id' => null, 'alias' => 'controllers'));
$this->Acl->Aco->save();

Both of these examples would create our ‘root’ or top level ACO which is going to be called ‘controllers’. The purpose of this root node is to make it easy to allow/deny access on a global application scope, and allow the use of the Acl for purposes not related to controllers/actions such as checking model record permissions. As we will be using a global root ACO we need to make a small modification to our AuthComponent configuration. AuthComponent needs to know about the existence of this root node, so that when making ACL checks it can use the correct node path when looking up controllers/actions. In AppController add the following to the beforeFilter:

$this->Auth->actionPath = 'controllers/';

An Automated tool for creating ACOs

As mentioned before, there is no pre-built way to input all of our controllers and actions into the Acl. However, we all hate doing repetitive things like typing in what could be hundreds of actions in a large application. We’ve whipped up an automated set of functions to build the ACO table. These functions will look at every controller in your application. It will add any non-private, non Controller methods to the Acl table, nicely nested underneath the owning controller. You can add and run this in your AppController or any controller for that matter, just be sure to remove it before putting your application into production.

    function build_acl() {
        if (!Configure::read('debug')) {
            return $this->_stop();
        }
        $log = array();

        $aco =& $this->Acl->Aco;
        $root = $aco->node('controllers');
        if (!$root) {
            $aco->create(array('parent_id' => null, 'model' => null, 'alias' => 'controllers'));
            $root = $aco->save();
            $root['Aco']['id'] = $aco->id;
            $log[] = 'Created Aco node for controllers';
        } else {
            $root = $root[0];
        }

        App::import('Core', 'File');
        $Controllers = Configure::listObjects('controller');
        $appIndex = array_search('App', $Controllers);
        if ($appIndex !== false ) {
            unset($Controllers[$appIndex]);
        }
        $baseMethods = get_class_methods('Controller');
        $baseMethods[] = 'buildAcl';

        $Plugins = $this->_getPluginControllerNames();
        $Controllers = array_merge($Controllers, $Plugins);

        // look at each controller in app/controllers
        foreach ($Controllers as $ctrlName) {
            $methods = $this->_getClassMethods($this->_getPluginControllerPath($ctrlName));

            // Do all Plugins First
            if ($this->_isPlugin($ctrlName)){
                $pluginNode = $aco->node('controllers/'.$this->_getPluginName($ctrlName));
                if (!$pluginNode) {
                    $aco->create(array('parent_id' => $root['Aco']['id'], 'model' => null, 'alias' => $this->_getPluginName($ctrlName)));
                    $pluginNode = $aco->save();
                    $pluginNode['Aco']['id'] = $aco->id;
                    $log[] = 'Created Aco node for ' . $this->_getPluginName($ctrlName) . ' Plugin';
                }
            }
            // find / make controller node
            $controllerNode = $aco->node('controllers/'.$ctrlName);
            if (!$controllerNode) {
                if ($this->_isPlugin($ctrlName)){
                    $pluginNode = $aco->node('controllers/' . $this->_getPluginName($ctrlName));
                    $aco->create(array('parent_id' => $pluginNode['0']['Aco']['id'], 'model' => null, 'alias' => $this->_getPluginControllerName($ctrlName)));
                    $controllerNode = $aco->save();
                    $controllerNode['Aco']['id'] = $aco->id;
                    $log[] = 'Created Aco node for ' . $this->_getPluginControllerName($ctrlName) . ' ' . $this->_getPluginName($ctrlName) . ' Plugin Controller';
                } else {
                    $aco->create(array('parent_id' => $root['Aco']['id'], 'model' => null, 'alias' => $ctrlName));
                    $controllerNode = $aco->save();
                    $controllerNode['Aco']['id'] = $aco->id;
                    $log[] = 'Created Aco node for ' . $ctrlName;
                }
            } else {
                $controllerNode = $controllerNode[0];
            }

            //clean the methods. to remove those in Controller and private actions.
            foreach ($methods as $k => $method) {
                if (strpos($method, '_', 0) === 0) {
                    unset($methods[$k]);
                    continue;
                }
                if (in_array($method, $baseMethods)) {
                    unset($methods[$k]);
                    continue;
                }
                $methodNode = $aco->node('controllers/'.$ctrlName.'/'.$method);
                if (!$methodNode) {
                    $aco->create(array('parent_id' => $controllerNode['Aco']['id'], 'model' => null, 'alias' => $method));
                    $methodNode = $aco->save();
                    $log[] = 'Created Aco node for '. $method;
                }
            }
        }
        if(count($log)>0) {
            debug($log);
        }
    }

    function _getClassMethods($ctrlName = null) {
        App::import('Controller', $ctrlName);
        if (strlen(strstr($ctrlName, '.')) > 0) {
            // plugin's controller
            $num = strpos($ctrlName, '.');
            $ctrlName = substr($ctrlName, $num+1);
        }
        $ctrlclass = $ctrlName . 'Controller';
        $methods = get_class_methods($ctrlclass);

        // Add scaffold defaults if scaffolds are being used
        $properties = get_class_vars($ctrlclass);
        if (array_key_exists('scaffold',$properties)) {
            if($properties['scaffold'] == 'admin') {
                $methods = array_merge($methods, array('admin_add', 'admin_edit', 'admin_index', 'admin_view', 'admin_delete'));
            } else {
                $methods = array_merge($methods, array('add', 'edit', 'index', 'view', 'delete'));
            }
        }
        return $methods;
    }

    function _isPlugin($ctrlName = null) {
        $arr = String::tokenize($ctrlName, '/');
        if (count($arr) > 1) {
            return true;
        } else {
            return false;
        }
    }

    function _getPluginControllerPath($ctrlName = null) {
        $arr = String::tokenize($ctrlName, '/');
        if (count($arr) == 2) {
            return $arr[0] . '.' . $arr[1];
        } else {
            return $arr[0];
        }
    }

    function _getPluginName($ctrlName = null) {
        $arr = String::tokenize($ctrlName, '/');
        if (count($arr) == 2) {
            return $arr[0];
        } else {
            return false;
        }
    }

    function _getPluginControllerName($ctrlName = null) {
        $arr = String::tokenize($ctrlName, '/');
        if (count($arr) == 2) {
            return $arr[1];
        } else {
            return false;
        }
    }

/**
 * Get the names of the plugin controllers ...
 *
 * This function will get an array of the plugin controller names, and
 * also makes sure the controllers are available for us to get the
 * method names by doing an App::import for each plugin controller.
 *
 * @return array of plugin names.
 *
 */
    function _getPluginControllerNames() {
        App::import('Core', 'File', 'Folder');
        $paths = Configure::getInstance();
        $folder =& new Folder();
        $folder->cd(APP . 'plugins');

        // Get the list of plugins
        $Plugins = $folder->read();
        $Plugins = $Plugins[0];
        $arr = array();

        // Loop through the plugins
        foreach($Plugins as $pluginName) {
            // Change directory to the plugin
            $didCD = $folder->cd(APP . 'plugins'. DS . $pluginName . DS . 'controllers');
            // Get a list of the files that have a file name that ends
            // with controller.php
            $files = $folder->findRecursive('.*_controller\.php');

            // Loop through the controllers we found in the plugins directory
            foreach($files as $fileName) {
                // Get the base file name
                $file = basename($fileName);

                // Get the controller name
                $file = Inflector::camelize(substr($file, 0, strlen($file)-strlen('_controller.php')));
                if (!preg_match('/^'. Inflector::humanize($pluginName). 'App/', $file)) {
                    if (!App::import('Controller', $pluginName.'.'.$file)) {
                        debug('Error importing '.$file.' for plugin '.$pluginName);
                    } else {
                        /// Now prepend the Plugin name ...
                        // This is required to allow us to fetch the method names.
                        $arr[] = Inflector::humanize($pluginName) . "/" . $file;
                    }
                }
            }
        }
        return $arr;
    }

Now run the action in your browser, eg. http://localhost/groups/build_acl, This will build your ACO table.

You might want to keep this function around as it will add new ACO’s for all of the controllers & actions that are in your application any time you run it. It does not remove nodes for actions that no longer exist though. Now that all the heavy lifting is done, we need to set up some permissions, and remove the code that disabled AuthComponent earlier.

The original code on this page did not take into account that you might use plugins for your application, and in order for you to have seamless plugin support in your Acl-controlled application, we have updated the above code to automatically include the correct plugins wherever necessary. Note that running this action will place some debug statements at the top of your browser page as to what Plugin/Controller/Action was added to the ACO tree and what was not.

Setting up permissions

Creating permissions much like creating ACO’s has no magic solution, nor will I be providing one. To allow ARO’s access to ACO’s from the shell interface use the AclShell. For more information on how to use it consult the aclShell help which can be accessed by running:

cake acl help

* needs to be quoted (‘*’)

To allow with the AclComponent do the following:

$this->Acl->allow($aroAlias, $acoAlias);

We are going to add in a few allow/deny statements now. Add the following to a temporary function in your UsersController and visit the address in your browser to run them. If you do a SELECT * FROM aros_acos you should see a whole pile of 1’s and 0’s. Once you’ve confirmed your permissions are set remove the function.

function initDB() {
    $group =& $this->User->Group;
    //Allow admins to everything
    $group->id = 1;
    $this->Acl->allow($group, 'controllers');

    //allow managers to posts and widgets
    $group->id = 2;
    $this->Acl->deny($group, 'controllers');
    $this->Acl->allow($group, 'controllers/Posts');
    $this->Acl->allow($group, 'controllers/Widgets');

    //allow users to only add and edit on posts and widgets
    $group->id = 3;
    $this->Acl->deny($group, 'controllers');
    $this->Acl->allow($group, 'controllers/Posts/add');
    $this->Acl->allow($group, 'controllers/Posts/edit');
    $this->Acl->allow($group, 'controllers/Widgets/add');
    $this->Acl->allow($group, 'controllers/Widgets/edit');
}

We now have set up some basic access rules. We’ve allowed administrators to everything. Managers can access everything in posts and widgets. While users can only access add and edit in posts & widgets.

We had to get a reference of a Group model and modify its id to be able to specify the ARO we wanted, this is due to how AclBehavior works. AclBehavior does not set the alias field in the aros table so we must use an object reference or an array to reference the ARO we want.

You may have noticed that I deliberately left out index and view from my Acl permissions. We are going to make view and index public actions in PostsController and WidgetsController. This allows non-authorized users to view these pages, making them public pages. However, at any time you can remove these actions from AuthComponent::allowedActions and the permissions for view and edit will revert to those in the Acl.

Now we want to take out the references to Auth->allowedActions in your users and groups controllers. Then add the following to your posts and widgets controllers:

function beforeFilter() {
    parent::beforeFilter();
    $this->Auth->allowedActions = array('index', 'view');
}

This removes the ‘off switches’ we put in earlier on the users and groups controllers, and gives public access on the index and view actions in posts and widgets controllers. In AppController::beforeFilter() add the following:

$this->Auth->allowedActions = array('display');

This makes the ‘display’ action public. This will keep our PagesController::display() public. This is important as often the default routing has this action as the home page for you application.

Logging in

Our application is now under access control, and any attempt to view non-public pages will redirect you to the login page. However, we will need to create a login view before anyone can login. Add the following to app/views/users/login.ctp if you haven’t done so already.

<h2>Login</h2>
<?php
echo $form->create('User', array('url' => array('controller' => 'users', 'action' =>'login')));
echo $form->input('User.username');
echo $form->input('User.password');
echo $form->end('Login');
?>

If a user is already logged in, redirect him:

function login() {
    if ($this->Session->read('Auth.User')) {
        $this->Session->setFlash('You are logged in!');
        $this->redirect('/', null, false);
    }
}

You may also want to add a flash() for Auth messages to your layout. Copy the default core layout - found at cake/libs/view/layouts/default.ctp - to your app layouts folder if you haven’t done so already. In app/views/layouts/default.ctp add

$session->flash('auth');

You should now be able to login and everything should work auto-magically. When access is denied Auth messages will be displayed if you added the $session->flash('auth')

Logout

Now onto the logout. Earlier we left this function blank, now is the time to fill it. In UsersController::logout() add the following:

$this->Session->setFlash('Good-Bye');
$this->redirect($this->Auth->logout());

This sets a Session flash message and logs out the User using Auth’s logout method. Auth’s logout method basically deletes the Auth Session Key and returns a url that can be used in a redirect. If there is other session data that needs to be deleted as well add that code here.

All done

You should now have an application controlled by Auth and Acl. Users permissions are set at the group level, but you can set them by user at the same time. You can also set permissions on a global and per-controller and per-action basis. Furthermore, you have a reusable block of code to easily expand your ACO table as your app grows.