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WP SAML Auth

Contributors: getpantheon, danielbachhuber, Outlandish Josh
Tags: authentication, SAML
Requires at least: 4.4
Tested up to: 5.0
Stable tag: 0.5.1
License: GPLv2 or later
License URI: http://www.gnu.org/licenses/gpl-2.0.html

SAML authentication for WordPress.

Description

Travis CI CircleCI

SAML authentication for WordPress, using the bundled OneLogin SAML library or optionally installed SimpleSAMLphp. OneLogin provides a SAML authentication bridge; SimpleSAMLphp provides SAML plus a variety of other authentication mechanisms. This plugin acts as a bridge between WordPress and the authentication library.

If your organization uses Google Apps, integrating Google Apps with WP SAML Auth takes just a few steps.

The standard user flow looks like this:

  • User can log in via SAML using a button added to the standard WordPress login view.
  • When the button is clicked, the user is handed off to the authentication library. With OneLogin, the user is redirected to the SAML identity provider. With SimpleSAMLphp, the user is redirected to the SimpleSAMLphp install.
  • Once the user is authenticated with the identity provider, they're redirected back to WordPress and signed in to their account. A new WordPress user will be created if none exists (although this behavior can be disabled).
  • When the user logs out of WordPress, they are also logged out of the identity provider.

A set of configuration options allow you to change the plugin's default behavior. For instance, permit_wp_login=>false will force all authentication to go through the SAML identity provider, bypassing wp-login.php. Similiarly, auto_provision=>false will disable automatic creation of new WordPress users.

See installation instructions for full configuration details.

Installation

This plugin requires access to a functioning SAML identity provider. If all you need is SAML authentication, then you should use the bundled OneLogin SAML library. If you have more complex authentication needs, then you can also use a SimpleSAMLphp installation running in the same environment.

To install SimpleSAMLphp locally for testing purposes, the Identity Provider QuickStart is a good place to start. On Pantheon, the SimpleSAMLphp web directory needs to be symlinked to ~/code/simplesaml to be properly handled by Nginx. Read the docs for more details about configuring SimpleSAMLphp on Pantheon.

Because SAML authentication is handled as a part of the login flow, your SAML identity provider will need to send responses back to wp-login.php. For instance, if your domain is pantheon.io, then you'd use http://pantheon.io/wp-login.php as your AssertionConsumerService configuration value.

Once you have access to a SAML identity provider, you can configure this plugin using a filter included in your theme's functions.php file or a mu-plugin:

function wpsax_filter_option( $value, $option_name ) {
    $defaults = array(
        /**
         * Type of SAML connection bridge to use.
         *
         * 'internal' uses OneLogin bundled library; 'simplesamlphp' uses SimpleSAMLphp.
         *
         * Defaults to SimpleSAMLphp for backwards compatibility.
         *
         * @param string
         */
        'connection_type' => 'internal',
        /**
         * Configuration options for OneLogin library use.
         *
         * See comments with "Required:" for values you absolutely need to configure.
         *
         * @param array
         */
        'internal_config'        => array(
            // Validation of SAML responses is required.
            'strict'       => true,
            'debug'        => defined( 'WP_DEBUG' ) && WP_DEBUG ? true : false,
            'baseurl'      => home_url(),
            'sp'           => array(
                'entityId' => 'urn:' . parse_url( home_url(), PHP_URL_HOST ),
                'assertionConsumerService' => array(
                    'url'  => wp_login_url(),
                    'binding' => 'urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST',
                ),
            ),
            'idp'          => array(
                // Required: Set based on provider's supplied value.
                'entityId' => '',
                'singleSignOnService' => array(
                    // Required: Set based on provider's supplied value.
                    'url'  => '',
                    'binding' => 'urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect',
                ),
                'singleLogoutService' => array(
                    // Required: Set based on provider's supplied value.
                    'url'  => '',
                    'binding' => 'urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect',
                ),
                // Required: Contents of the IDP's public x509 certificate.
                // Use file_get_contents() to load certificate contents into scope.
                'x509cert' => '',
                // Optional: Instead of using the x509 cert, you can specify the fingerprint and algorithm.
                'certFingerprint' => '',
                'certFingerprintAlgorithm' => '',
            ),
        ),
        /**
         * Path to SimpleSAMLphp autoloader.
         *
         * Follow the standard implementation by installing SimpleSAMLphp
         * alongside the plugin, and provide the path to its autoloader.
         * Alternatively, this plugin will work if it can find the
         * `SimpleSAML_Auth_Simple` class.
         *
         * @param string
         */
        'simplesamlphp_autoload' => dirname( __FILE__ ) . '/simplesamlphp/lib/_autoload.php',
        /**
         * Authentication source to pass to SimpleSAMLphp
         *
         * This must be one of your configured identity providers in
         * SimpleSAMLphp. If the identity provider isn't configured
         * properly, the plugin will not work properly.
         *
         * @param string
         */
        'auth_source'            => 'default-sp',
        /**
         * Whether or not to automatically provision new WordPress users.
         *
         * When WordPress is presented with a SAML user without a
         * corresponding WordPress account, it can either create a new user
         * or display an error that the user needs to contact the site
         * administrator.
         *
         * @param bool
         */
        'auto_provision'         => true,
        /**
         * Whether or not to permit logging in with username and password.
         *
         * If this feature is disabled, all authentication requests will be
         * channeled through SimpleSAMLphp.
         *
         * @param bool
         */
        'permit_wp_login'        => true,
        /**
         * Attribute by which to get a WordPress user for a SAML user.
         *
         * @param string Supported options are 'email' and 'login'.
         */
        'get_user_by'            => 'email',
        /**
         * SAML attribute which includes the user_login value for a user.
         *
         * @param string
         */
        'user_login_attribute'   => 'uid',
        /**
         * SAML attribute which includes the user_email value for a user.
         *
         * @param string
         */
        'user_email_attribute'   => 'mail',
        /**
         * SAML attribute which includes the display_name value for a user.
         *
         * @param string
         */
        'display_name_attribute' => 'display_name',
        /**
         * SAML attribute which includes the first_name value for a user.
         *
         * @param string
         */
        'first_name_attribute' => 'first_name',
        /**
         * SAML attribute which includes the last_name value for a user.
         *
         * @param string
         */
        'last_name_attribute' => 'last_name',
        /**
         * Default WordPress role to grant when provisioning new users.
         *
         * @param string
         */
        'default_role'           => get_option( 'default_role' ),
    );
    $value = isset( $defaults[ $option_name ] ) ? $defaults[ $option_name ] : $value;
    return $value;
}
add_filter( 'wp_saml_auth_option', 'wpsax_filter_option', 10, 2 );

If you need to adapt authentication behavior based on the SAML response, you can do so with the wp_saml_auth_pre_authentication filter:

/**
 * Reject authentication if $attributes doesn't include the authorized group.
 */
add_filter( 'wp_saml_auth_pre_authentication', function( $ret, $attributes ) {
    if ( empty( $attributes['group'] ) || ! in_array( 'administrators', $attributes['group'] ) ) {
        return new WP_Error( 'unauthorized-group', "Sorry, you're not a member of an authorized group." );
    }
    return $ret;
}, 10, 2 );

WP-CLI Commands

This plugin implements a variety of WP-CLI commands. All commands are grouped into the wp saml-auth namespace.

$ wp help saml-auth

NAME

  wp saml-auth

DESCRIPTION

  Configure and manage the WP SAML Auth plugin.

SYNOPSIS

  wp saml-auth <command>

SUBCOMMANDS

  scaffold-config      Scaffold a configuration filter to customize WP SAML Auth usage.

Use wp help saml-auth <command> to learn more about each command.

Contributing

The best way to contribute to the development of this plugin is by participating on the GitHub project:

https://github.com/pantheon-systems/wp-saml-auth

Pull requests and issues are welcome!

You may notice there are two sets of tests running, on two different services:

  • Travis CI runs the PHPUnit test suite, which mocks interactions with SimpleSAMLphp.
  • Circle CI runs the Behat test suite against a Pantheon site, to ensure the plugin's compatibility with the Pantheon platform. This includes configuring a fully-functional instance of SimpleSAMLphp.

Both of these test suites can be run locally, with a varying amount of setup.

PHPUnit requires the WordPress PHPUnit test suite, and access to a database with name wordpress_test. If you haven't already configured the test suite locally, you can run bash bin/install-wp-tests.sh wordpress_test root '' localhost.

Behat requires a Pantheon site. Once you've created the site, you'll need install Terminus, and set the TERMINUS_TOKEN, TERMINUS_SITE, and TERMINUS_ENV environment variables. Then, you can run ./bin/behat-prepare.sh to prepare the site for the test suite.

Frequently Asked Questions

Can I update an existing WordPress user's data when they log back in?

If you'd like to make sure the user's display name, first name, and last name are updated in WordPress when they log back in, you can use the following code snippet:

/**
 * Update user attributes after a user has logged in via SAML.
 */
add_action( 'wp_saml_auth_existing_user_authenticated', function( $existing_user, $attributes ) {
    $user_args = array(
        'ID' => $existing_user->ID,
    );
    foreach ( array( 'display_name', 'first_name', 'last_name' ) as $type ) {
        $attribute          = \WP_SAML_Auth::get_option( "{$type}_attribute" );
        $user_args[ $type ] = ! empty( $attributes[ $attribute ][0] ) ? $attributes[ $attribute ][0] : '';
    }
    wp_update_user( $user_args );
}, 10, 2 );

The wp_saml_auth_existing_user_authenticated action fires after the user has successfully authenticated with the SAML IdP. The code snippet then uses a pattern similar to WP SAML Auth to fetch display name, first name, and last name from the SAML response. Lastly, the code snippet updates the existing WordPress user object.

How do I use SimpleSAMLphp and WP SAML Auth on a multi web node environment?

Because SimpleSAMLphp uses PHP sessions to manage user authentication, it will work unreliably or not at all on a server configuration with multiple web nodes. This is because PHP's default session handler uses the filesystem, and each web node has a different filesystem. Fortunately, there's a way around this.

First, install and activate the WP Native PHP Sessions plugin, which registers a database-based PHP session handler for WordPress to use.

Next, modify SimpleSAMLphp's www/_include.php file to require wp-load.php. If you installed SimpleSAMLphp within the wp-saml-auth directory, you'd edit wp-saml-auth/simplesamlphp/www/_include.php to include:

<?php
require_once dirname( dirname( dirname( dirname( dirname( dirname( __FILE__ ) ) ) ) ) ) . '/wp-load.php';

Note: the declaration does need to be at the top of _include.php, to ensure WordPress (and thus the session handling) is loaded before SimpleSAMLphp.

There is no third step. Because SimpleSAMLphp loads WordPress, which has WP Native PHP Sessions active, SimpleSAMLphp and WP SAML Auth will be able to communicate to one another on a multi web node environment.

Changelog

0.5.1 (November 15, 2018)

  • Introduces a wp_saml_auth_attributes filter to permit modifying SAML response attributes before they're processed by WordPress [#136].

0.5.0 (November 7, 2018)

  • Updates onelogin/php-saml to v3.0.0 for PHP 7.2 support [#133].

0.4.0 (September 5, 2018)

  • Updates onelogin/php-saml from v2.13.0 to v2.14.0 [#127].

0.3.11 (July 18, 2018)

  • Provides an error message explicitly for when SAML response attributes are missing [#125].

0.3.10 (June 28, 2018)

  • Ensures redirect_to URLs don't lose query parameters by encoding with rawurlencode() [#124].
  • Adds French localization.

0.3.9 (March 29, 2018)

  • Fixes PHP notice by using namespaced SimpleSAMLphp class if available [#118].
  • Updates onelogin/php-saml from v2.12.0 to v2.13.0

0.3.8 (February 26, 2018)

  • Redirects to action=wp-saml-auth when redirect_to is persisted, to ensure authentication is handled [#115].

0.3.7 (February 13, 2018)

  • Persists redirect_to value in a more accurate manner, as a follow up to the change in v0.3.6 [#113].

0.3.6 (February 7, 2018)

  • Prevents WordPress from dropping authentication cookie when user is redirected to login from /wp-admin/ URLs [#112].

0.3.5 (January 19, 2018)

  • Substitutes wp-login.php string with parse_url( wp_login_url(), PHP_URL_PATH ) for compatibility with plugins and functions that alter the standard login url [#109].

0.3.4 (December 22, 2017)

  • Permits internal connection type to be used without signout URL, for integration with Google Apps [#106].

0.3.3 (November 28, 2017)

  • Forwards 'redirect_to' parameter to SAML Authentication to enable deep links [#103].

0.3.2 (November 9, 2017)

  • Updates onelogin/php-saml dependency from v2.10.7 to v2.12.0 [#90, #99].

0.3.1 (July 12, 2017)

  • Passes $attributes to wp_saml_auth_insert_user filter, so user creation behavior can be modified based on SAML response.

0.3.0 (June 29, 2017)

  • Includes OneLogin's PHP SAML library for SAML auth without SimpleSAMLphp. See "Installation" for configuration instructions.
  • Fixes handling of SAMLResponse when permit_wp_login=true.

0.2.2 (May 24, 2017)

  • Introduces a wp_saml_auth_login_strings filter to permit login text strings to be filterable.
  • Introduces a wp_saml_auth_pre_authentication filter to allow authentication behavior to be adapted based on SAML response.
  • Improves error message when required SAML response attribute is missing.
  • Corrects project name in composer.json.

0.2.1 (March 22, 2017)

  • Introduces wp_saml_auth_new_user_authenticated and wp_saml_auth_existing_user_authenticated actions to permit themes / plugins to run a callback post-authentication.
  • Runs Behat test suite against latest stable SimpleSAMLphp, instead of a pinned version.

0.2.0 (March 7, 2017)

  • Introduces wp saml-auth scaffold-config, a WP-CLI command to scaffold a configuration filter to customize WP SAML Auth usage.
  • Redirects back to WordPress after SimpleSAMLPHP authentication.
  • Variety of test suite improvements.

0.1.0 (April 18, 2016)

  • Initial release.