Allow regenerating site secret

9 files changed, 331 insertions, 3 deletions

diff --git a/actions/admin/site/regenerate_secret.php b/actions/admin/site/regenerate_secret.php
new file mode 100644
index 000000000..3112fb5f3
--- /dev/null
+++ b/actions/admin/site/regenerate_secret.php
@@ -0,0 +1,11 @@
+<?php
+/**
+ * Generate a new site secret
+ */
+
+init_site_secret();
+elgg_reset_system_cache();
+
+system_message(elgg_echo('admin:site:secret_regenerated'));
+
+forward(REFERER);
diff --git a/engine/classes/ElggCrypto.php b/engine/classes/ElggCrypto.php
new file mode 100644
index 000000000..b6a8b2024
--- /dev/null
+++ b/engine/classes/ElggCrypto.php
@@ -0,0 +1,208 @@
+<?php
+/**
+ * ElggCrypto
+ *
+ * @package    Elgg.Core
+ * @subpackage Crypto
+ *
+ * @access private
+ */
+class ElggCrypto {
+
+	/**
+	 * Character set for temp passwords (no risk of embedded profanity/glyphs that look similar)
+	 */
+	const CHARS_PASSWORD = 'bcdfghjklmnpqrstvwxyz2346789';
+
+	/**
+	 * Generate a string of highly randomized bytes (over the full 8-bit range).
+	 *
+	 * @param int $length Number of bytes needed
+	 * @return string Random bytes
+	 *
+	 * @author George Argyros <argyros.george@gmail.com>
+	 * @copyright 2012, George Argyros. All rights reserved.
+	 * @license Modified BSD
+	 * @link https://github.com/GeorgeArgyros/Secure-random-bytes-in-PHP/blob/master/srand.php Original
+	 *
+	 * Redistribution and use in source and binary forms, with or without
+	 * modification, are permitted provided that the following conditions are met:
+	 *    * Redistributions of source code must retain the above copyright
+	 *      notice, this list of conditions and the following disclaimer.
+	 *    * Redistributions in binary form must reproduce the above copyright
+	 *      notice, this list of conditions and the following disclaimer in the
+	 *      documentation and/or other materials provided with the distribution.
+	 *    * Neither the name of the <organization> nor the
+	 *      names of its contributors may be used to endorse or promote products
+	 *      derived from this software without specific prior written permission.
+	 *
+	 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+	 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+	 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+	 * DISCLAIMED. IN NO EVENT SHALL GEORGE ARGYROS BE LIABLE FOR ANY
+	 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+	 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+	 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+	 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+	 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+	 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+	 */
+	public function getRandomBytes($length) {
+		/**
+		 * Our primary choice for a cryptographic strong randomness function is
+		 * openssl_random_pseudo_bytes.
+		 */
+		$SSLstr = '4'; // http://xkcd.com/221/
+		if (function_exists('openssl_random_pseudo_bytes')
+				&& (version_compare(PHP_VERSION, '5.3.4') >= 0 || substr(PHP_OS, 0, 3) !== 'WIN')) {
+			$SSLstr = openssl_random_pseudo_bytes($length, $strong);
+			if ($strong) {
+				return $SSLstr;
+			}
+		}
+
+		/**
+		 * If mcrypt extension is available then we use it to gather entropy from
+		 * the operating system's PRNG. This is better than reading /dev/urandom
+		 * directly since it avoids reading larger blocks of data than needed.
+		 * Older versions of mcrypt_create_iv may be broken or take too much time
+		 * to finish so we only use this function with PHP 5.3.7 and above.
+		 * @see https://bugs.php.net/bug.php?id=55169
+		 */
+		if (function_exists('mcrypt_create_iv')
+				&& (version_compare(PHP_VERSION, '5.3.7') >= 0 || substr(PHP_OS, 0, 3) !== 'WIN')) {
+			$str = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
+			if ($str !== false) {
+				return $str;
+			}
+		}
+
+		/**
+		 * No build-in crypto randomness function found. We collect any entropy
+		 * available in the PHP core PRNGs along with some filesystem info and memory
+		 * stats. To make this data cryptographically strong we add data either from
+		 * /dev/urandom or if its unavailable, we gather entropy by measuring the
+		 * time needed to compute a number of SHA-1 hashes.
+		 */
+		$str = '';
+		$bits_per_round = 2; // bits of entropy collected in each clock drift round
+		$msec_per_round = 400; // expected running time of each round in microseconds
+		$hash_len = 20; // SHA-1 Hash length
+		$total = $length; // total bytes of entropy to collect
+
+		$handle = @fopen('/dev/urandom', 'rb');
+		if ($handle && function_exists('stream_set_read_buffer')) {
+			@stream_set_read_buffer($handle, 0);
+		}
+
+		do {
+			$bytes = ($total > $hash_len)? $hash_len : $total;
+			$total -= $bytes;
+
+			//collect any entropy available from the PHP system and filesystem
+			$entropy = rand() . uniqid(mt_rand(), true) . $SSLstr;
+			$entropy .= implode('', @fstat(@fopen( __FILE__, 'r')));
+			$entropy .= memory_get_usage() . getmypid();
+			$entropy .= serialize($_ENV) . serialize($_SERVER);
+			if (function_exists('posix_times')) {
+				$entropy .= serialize(posix_times());
+			}
+			if (function_exists('zend_thread_id')) {
+				$entropy .= zend_thread_id();
+			}
+
+			if ($handle) {
+				$entropy .= @fread($handle, $bytes);
+			} else  {
+				// Measure the time that the operations will take on average
+				for ($i = 0; $i < 3; $i++) {
+					$c1 = microtime(true);
+					$var = sha1(mt_rand());
+					for ($j = 0; $j < 50; $j++) {
+						$var = sha1($var);
+					}
+					$c2 = microtime(true);
+					$entropy .= $c1 . $c2;
+				}
+
+				// Based on the above measurement determine the total rounds
+				// in order to bound the total running time.
+				$rounds = (int) ($msec_per_round * 50 / (int) (($c2 - $c1) * 1000000));
+
+				// Take the additional measurements. On average we can expect
+				// at least $bits_per_round bits of entropy from each measurement.
+				$iter = $bytes * (int) (ceil(8 / $bits_per_round));
+
+				for ($i = 0; $i < $iter; $i++) {
+					$c1 = microtime();
+					$var = sha1(mt_rand());
+					for ($j = 0; $j < $rounds; $j++) {
+						$var = sha1($var);
+					}
+					$c2 = microtime();
+					$entropy .= $c1 . $c2;
+				}
+			}
+
+			// We assume sha1 is a deterministic extractor for the $entropy variable.
+			$str .= sha1($entropy, true);
+
+		} while ($length > strlen($str));
+
+		if ($handle) {
+			@fclose($handle);
+		}
+
+		return substr($str, 0, $length);
+	}
+
+	/**
+	 * Generate a random string of specified length.
+	 *
+	 * Uses supplied character list for generating the new string.
+	 * If no character list provided - uses Base64 URL character set.
+	 *
+	 * @param  int         $length Desired length of the string
+	 * @param  string|null $chars  Characters to be chosen from randomly. If not given, the Base64 URL
+	 *                             charset will be used.
+	 *
+	 * @return string The random string
+	 *
+	 * @throws InvalidArgumentException
+	 *
+	 * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+	 * @license   http://framework.zend.com/license/new-bsd New BSD License
+	 *
+	 * @see https://github.com/zendframework/zf2/blob/master/library/Zend/Math/Rand.php#L179
+	 */
+	public static function getRandomString($length, $chars = null) {
+		if ($length < 1) {
+			throw new InvalidArgumentException('Length should be >= 1');
+		}
+
+		if (empty($chars)) {
+			$numBytes = ceil($length * 0.75);
+			$bytes    = self::getRandomBytes($numBytes);
+			$string = substr(rtrim(base64_encode($bytes), '='), 0, $length);
+
+			// Base64 URL
+			return strtr($string, '+/', '-_');
+		}
+
+		$listLen = strlen($chars);
+
+		if ($listLen == 1) {
+			return str_repeat($chars, $length);
+		}
+
+		$bytes  = self::getRandomBytes($length);
+		$pos    = 0;
+		$result = '';
+		for ($i = 0; $i < $length; $i++) {
+			$pos     = ($pos + ord($bytes[$i])) % $listLen;
+			$result .= $chars[$pos];
+		}
+
+		return $result;
+	}
+}
diff --git a/engine/lib/actions.php b/engine/lib/actions.php
index 56936f582..8047914ac 100644
--- a/engine/lib/actions.php
+++ b/engine/lib/actions.php
@@ -364,16 +364,19 @@ function generate_action_token($timestamp) {
 }
 
 /**
- * Initialise the site secret hash.
+ * Initialise the site secret (32 bytes: "z" to indicate format + 186-bit key in Base64 URL).
  *
  * Used during installation and saves as a datalist.
  *
+ * Note: Old secrets were hex encoded.
+ *
  * @return mixed The site secret hash or false
  * @access private
  * @todo Move to better file.
  */
 function init_site_secret() {
-	$secret = md5(rand() . microtime());
+	$secret = 'z' . ElggCrypto::getRandomString(31);
+
 	if (datalist_set('__site_secret__', $secret)) {
 		return $secret;
 	}
@@ -400,6 +403,26 @@ function get_site_secret() {
 }
 
 /**
+ * Get the strength of the site secret
+ *
+ * @return string "strong", "moderate", or "weak"
+ * @access private
+ */
+function _elgg_get_site_secret_strength() {
+	$secret = get_site_secret();
+	if ($secret[0] !== 'z') {
+		$rand_max = getrandmax();
+		if ($rand_max < pow(2, 16)) {
+			return 'weak';
+		}
+		if ($rand_max < pow(2, 32)) {
+			return 'moderate';
+		}
+	}
+	return 'strong';
+}
+
+/**
  * Check if an action is registered and its script exists.
  *
  * @param string $action Action name
diff --git a/engine/lib/admin.php b/engine/lib/admin.php
index 7f82108c0..f36f29668 100644
--- a/engine/lib/admin.php
+++ b/engine/lib/admin.php
@@ -236,6 +236,7 @@ function admin_init() {
 	elgg_register_action('admin/site/update_advanced', '', 'admin');
 	elgg_register_action('admin/site/flush_cache', '', 'admin');
 	elgg_register_action('admin/site/unlock_upgrade', '', 'admin');
+	elgg_register_action('admin/site/regenerate_secret', '', 'admin');
 
 	elgg_register_action('admin/menu/save', '', 'admin');
 
@@ -291,6 +292,7 @@ function admin_init() {
 	elgg_register_admin_menu_item('configure', 'settings', null, 100);
 	elgg_register_admin_menu_item('configure', 'basic', 'settings', 10);
 	elgg_register_admin_menu_item('configure', 'advanced', 'settings', 20);
+	elgg_register_admin_menu_item('configure', 'advanced/site_secret', 'settings', 25);
 	elgg_register_admin_menu_item('configure', 'menu_items', 'appearance', 30);
 	elgg_register_admin_menu_item('configure', 'profile_fields', 'appearance', 40);
 	// default widgets is added via an event handler elgg_default_widgets_init() in widgets.php
diff --git a/engine/lib/upgrades/2013060900-1.8.15-site_secret-404fc165cf9e0ac9.php b/engine/lib/upgrades/2013060900-1.8.15-site_secret-404fc165cf9e0ac9.php
new file mode 100644
index 000000000..b5b614762
--- /dev/null
+++ b/engine/lib/upgrades/2013060900-1.8.15-site_secret-404fc165cf9e0ac9.php
@@ -0,0 +1,13 @@
+<?php
+/**
+ * Elgg 1.8.15 upgrade 2013060900
+ * site_secret
+ *
+ * Description
+ */
+
+$strength = _elgg_get_site_secret_strength();
+
+if ($strength !== 'strong') {
+	elgg_add_admin_notice('weak_site_key', elgg_echo("upgrade:site_secret_warning:$strength"));
+}
diff --git a/languages/en.php b/languages/en.php
index ad4831db7..4eed63d4c 100644
--- a/languages/en.php
+++ b/languages/en.php
@@ -597,10 +597,24 @@ $english = array(
 	'admin:settings' => 'Settings',
 	'admin:settings:basic' => 'Basic Settings',
 	'admin:settings:advanced' => 'Advanced Settings',
+	'admin:settings:advanced/site_secret' => 'Site Secret',
 	'admin:site:description' => "This admin panel allows you to control global settings for your site. Choose an option below to get started.",
+	'admin:settings:advanced:site_secret' => 'Site Secret',
 	'admin:site:opt:linktext' => "Configure site...",
 	'admin:site:access:warning' => "Changing the access setting only affects the permissions on content created in the future.",
 
+	'admin:site:secret:intro' => 'Elgg uses a key to create security tokens for various purposes.',
+	'admin:site:secret_regenerated' => "Your site secret has been regenerated.",
+	'admin:site:secret:regenerate' => "Regenerate site secret",
+	'admin:site:secret:regenerate:help' => "Note: This may inconvenience some users by invalidating tokens used in \"remember me\" cookies, e-mail validation requests, invitation codes, etc.",
+	'site_secret:current_strength' => 'Key Strength',
+	'site_secret:strength:weak' => "Weak",
+	'site_secret:strength_msg:weak' => "We strongly recommend that you regenerate your site secret.",
+	'site_secret:strength:moderate' => "Moderate",
+	'site_secret:strength_msg:moderate' => "We recommend you regenerate your site secret for the best site security.",
+	'site_secret:strength:strong' => "Strong",
+	'site_secret:strength_msg:strong' => "&#x2713; Your site secret is sufficiently strong.",
+
 	'admin:dashboard' => 'Dashboard',
 	'admin:widget:online_users' => 'Online users',
 	'admin:widget:online_users:help' => 'Lists the users currently on the site',
@@ -1064,7 +1078,7 @@ Once you have logged in, we highly recommend that you change your password.
 	'upgrade:unlock' => 'Unlock upgrade',
 	'upgrade:unlock:confirm' => "The database is locked for another upgrade. Running concurrent upgrades is dangerous. You should only continue if you know there is not another upgrade running. Unlock?",
 	'upgrade:locked' => "Cannot upgrade. Another upgrade is running. To clear the upgrade lock, visit the Admin section.",
-	'upgrade:unlock:success' => "Upgrade unlocked suscessfully.",
+	'upgrade:unlock:success' => "Upgrade unlocked successfully.",
 	'upgrade:unable_to_upgrade' => 'Unable to upgrade.',
 	'upgrade:unable_to_upgrade_info' =>
 		'This installation cannot be upgraded because legacy views
@@ -1079,6 +1093,8 @@ Once you have logged in, we highly recommend that you change your password.
 
 	'update:twitter_api:deactivated' => 'Twitter API (previously Twitter Service) was deactivated during the upgrade. Please activate it manually if required.',
 	'update:oauth_api:deactivated' => 'OAuth API (previously OAuth Lib) was deactivated during the upgrade.  Please activate it manually if required.',
+	'upgrade:site_secret_warning:moderate' => "You are encouraged to regenerate your site key to improve system security. See Configure &gt; Site Secret",
+	'upgrade:site_secret_warning:weak' => "You are strongly encouraged to regenerate your site key to improve system security. See Configure &gt; Site Secret",
 
 	'deprecated:function' => '%s() was deprecated by %s()',
 
diff --git a/views/default/admin/settings/advanced/site_secret.php b/views/default/admin/settings/advanced/site_secret.php
new file mode 100644
index 000000000..e70ac7ab6
--- /dev/null
+++ b/views/default/admin/settings/advanced/site_secret.php
@@ -0,0 +1,11 @@
+<?php
+/**
+ * Elgg administration site secret settings
+ *
+ * @package Elgg
+ * @subpackage Core
+ */
+
+echo elgg_view_form('admin/site/regenerate_secret', array(), array(
+	'strength' => _elgg_get_site_secret_strength(),
+));
diff --git a/views/default/css/admin.php b/views/default/css/admin.php
index 3896ded5d..c435621b2 100644
--- a/views/default/css/admin.php
+++ b/views/default/css/admin.php
@@ -1544,6 +1544,26 @@ table.mceLayout {
 }
 
 /* ***************************************
+    SITE SECRET
+*************************************** */
+.elgg-form-admin-site-regenerate-secret table {
+	width: 60%;
+	margin: 1em auto;
+}
+td.elgg-strength-strong,
+td.elgg-strength-strong h4 {
+	background: #DFF0D8; color: #468847;
+}
+td.elgg-strength-moderate,
+td.elgg-strength-moderate h4 {
+	background: #FCF8E3; color: #C09853;
+}
+td.elgg-strength-weak,
+td.elgg-strength-weak h4 {
+	background: #F2DEDE; color: #B94A48;
+}
+
+/* ***************************************
 	HELPERS
 *************************************** */
 .hidden {
diff --git a/views/default/forms/admin/site/regenerate_secret.php b/views/default/forms/admin/site/regenerate_secret.php
new file mode 100644
index 000000000..af269b801
--- /dev/null
+++ b/views/default/forms/admin/site/regenerate_secret.php
@@ -0,0 +1,24 @@
+<?php
+
+$strength = $vars['strength'];
+
+?>
+<p><?php echo elgg_echo('admin:site:secret:intro'); ?></p>
+
+<table class="elgg-table">
+	<tr>
+		<th><?php echo elgg_echo('site_secret:current_strength'); ?></th>
+		<td class="elgg-strength-<?php echo $strength; ?>">
+			<h4><?php echo elgg_echo("site_secret:strength:$strength"); ?></h4>
+			<div><?php echo elgg_echo("site_secret:strength_msg:$strength"); ?></div>
+		</td>
+	</tr>
+</table>
+
+<div class="elgg-foot">
+	<?php echo elgg_view('input/submit', array(
+			'value' => elgg_echo('admin:site:secret:regenerate'),
+			'class' => 'elgg-requires-confirmation elgg-button elgg-button-submit',
+		)); ?>
+	<p class="elgg-text-help mts"><?php echo elgg_echo('admin:site:secret:regenerate:help'); ?></p>
+</div>