Rework session handling; add CSRF tokens and autologin

includes/config.inc.php-dist

@@ -20,6 +20,9 @@ $allowzoneadd = FALSE;  # Allow normal users to add zones
 
 $authdb  = "../etc/pdns.users.sqlite3";
 
+# Set a random generated secret to enable auto-login and long living csrf tokens
+// $secret = '...';
+
 $templates = array();
 /*
 $templates[] = array(
@@ -57,5 +60,3 @@ if (!file_exists($authdb)) {
     $salt = bin2hex(openssl_random_pseudo_bytes(16));
     $db->exec("INSERT INTO users (emailaddress, password, isadmin) VALUES ('admin', '".crypt("admin", '$6$'.$salt)."', 1)");
 }
-
-?>

includes/session.inc.php

@@ -4,102 +4,286 @@ include_once('config.inc.php');
 include_once('misc.inc.php');
 include_once('wefactauth.inc.php');
 
-session_start();
+global $current_user;
 
-function is_logged_in() {
-    if (isset($_SESSION['logged_in']) && $_SESSION['logged_in'] == "true") {
-        return TRUE;
+$current_user = false;
+
+// session startup
+function _set_current_user($username, $is_admin = false, $has_csrf_token = false, $is_api = false) {
+    global $current_user;
+
+    $current_user = array(
+        'username' => $username,
+        'is_admin' => $is_admin,
+        'has_csrf_token' => $has_csrf_token,
+        'is_api' => $is_api,
+    );
+}
+
+function _check_csrf_token($user) {
+    global $secret;
+
+    if (isset($_SERVER['HTTP_X_CSRF_TOKEN']) && $_SERVER['HTTP_X_CSRF_TOKEN']) {
+        $found_token = $_SERVER['HTTP_X_CSRF_TOKEN'];
+    } elseif (isset($_POST['csrf-token']) && $_POST['csrf-token']) {
+        $found_token = $_POST['csrf-token'];
     } else {
-        global $adminapikey;
-        global $adminapiips;
+        $found_token = '';
+    }
 
-        if (isset($adminapikey) && isset($adminapiips)) {
-            if (array_search($_SERVER['REMOTE_ADDR'], $adminapiips) !== FALSE) {
-                if ($_POST['adminapikey'] == $adminapikey) {
-                    # Allow this request, fake that we're logged in.
-                    set_logged_in('admin');
-                    set_is_adminuser();
-                    $_SESSION['apientrance'] = 'true';
-                    return TRUE;
-                }
-            }
+    if (isset($secret) && $secret) {
+        # if we have a secret keep csrf-token valid across logins
+        $csrf_hmac_secret = hash_pbkdf2('sha256', 'csrf_hmac', $secret, 100, 0, true);
+        $userinfo = base64_encode($user['emailaddress']) . ':' . base64_encode($user['password']);
+        $csrf_token = base64_encode(hash_hmac('sha256', $userinfo, $csrf_hmac_secret, true));
+    } else {
+        # without secret create new token for each session
+        if (!isset($_SESSION['csrf_token'])) {
+            $_SESSION['csrf_token'] = base64_encode(openssl_random_pseudo_bytes(32));
         }
-        return FALSE;
+        $csrf_token = $_SESSION['csrf_token'];
     }
-}
 
-function set_apiuser() {
-    $_SESSION['apientrance'] = 'true';
-}
-
-function is_apiuser() {
-    if (isset($_SESSION['apientrance']) && $_SESSION['apientrance'] = 'true') {
-        return TRUE;
+    if ($found_token === $csrf_token) {
+        global $current_user;
+        $current_user['has_csrf_token'] = true;
     }
-    return FALSE;
+
+    define('CSRF_TOKEN', $csrf_token);
+    header("X-CSRF-Token: ${csrf_token}");
 }
 
-function set_logged_in($login_user) {
-    $_SESSION['logged_in'] = 'true';
-    $_SESSION['username']  = $login_user;
-}
+function enc_secret($message) {
+    global $secret;
 
-function set_is_adminuser() {
-    $_SESSION['is_adminuser'] = 'true';
-}
+    if (isset($secret) && $secret) {
+        $enc_secret = hash_pbkdf2('sha256', 'encryption', $secret, 100, 0, true);
+        $hmac_secret = hash_pbkdf2('sha256', 'encryption_hmac', $secret, 100, 0, true);
 
-function is_adminuser() {
-    if (isset($_SESSION['is_adminuser']) && $_SESSION['is_adminuser'] == 'true') {
-        return TRUE;
-    } else {
-        return FALSE;
+        $mcrypt = mcrypt_module_open(MCRYPT_RIJNDAEL_256, '', MCRYPT_MODE_CBC, '') or die('missing mcrypt');
+
+        # add PKCS#7 padding
+        $blocksize = mcrypt_get_block_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
+        $padlength = $blocksize - (strlen($message) % $blocksize);
+        $message .= str_repeat(chr($padlength), $padlength);
+
+        $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
+        $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
+        $ciphertext = $iv . mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $enc_secret, $message, MCRYPT_MODE_CBC, $iv);
+        mcrypt_module_close($mcrypt);
+
+        $mac = hash_hmac('sha256', $ciphertext, $hmac_secret, true);
+        return 'enc:' . base64_encode($ciphertext) . ':' . base64_encode($mac);
     }
+
+    return base64_encode($message);
 }
 
-function get_sess_user() {
-    return $_SESSION['username'];
+function dec_secret($code) {
+    global $secret;
+    $is_encrypted = (substr($code, 0, 4) === 'enc:');
+    if (isset($secret) && $secret) {
+        if (!$is_encrypted) return false;
+
+        $msg = explode(':', $code);
+        if (3 != count($msg)) return false;
+
+        $enc_secret = hash_pbkdf2('sha256', 'encryption', $secret, 100, 0, true);
+        $hmac_secret = hash_pbkdf2('sha256', 'encryption_hmac', $secret, 100, 0, true);
+
+        $msg[1] = base64_decode($msg[1]);
+        $msg[2] = base64_decode($msg[2]);
+
+        $mac = hash_hmac('sha256', $msg[1], $hmac_secret, true);
+        # compare hashes first: this should prevent any timing leak
+        if (hash('sha256', $mac, true) !== hash('sha256', $msg[2], true)) return false;
+        if ($mac !== $msg[2]) return false;
+
+        $mcrypt = mcrypt_module_open(MCRYPT_RIJNDAEL_256, '', MCRYPT_MODE_CBC, '') or die('missing mcrypt');
+        $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
+        $iv = substr($msg[1], 0, $iv_size);
+        $ciphertext = substr($msg[1], $iv_size);
+        $plaintext = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $enc_secret, $ciphertext, MCRYPT_MODE_CBC, $iv);
+        mcrypt_module_close($mcrypt);
+
+        # remove PKCS#7 padding
+        $len = strlen($plaintext);
+        $padlength = ord($plaintext[$len-1]);
+        $plaintext = substr($plaintext, 0, $len - $padlength);
+
+        return $plaintext;
+    }
+
+    if ($is_encrypted) return false;
+    return base64_decode($code);
 }
 
-function logout() {
-    session_destroy();
+function _unset_cookie($name) {
+    $is_ssl = isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off';
+    setcookie($name, null, -1, null, null, $is_ssl);
+}
+
+function _store_auto_login($value) {
+    $is_ssl = isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off';
+    // set for 30 days
+    setcookie('NSEDIT_AUTOLOGIN', $value, time()+60*60*24*30, null, null, $is_ssl);
 }
 
 function try_login() {
-    global $wefactapiurl;
-    global $wefactapikey;
-
     if (isset($_POST['username']) and isset($_POST['password'])) {
-        if (valid_user($_POST['username']) === FALSE) {
-            return FALSE;
-        }
-        $do_local_auth = 1;
+        if (_try_login($_POST['username'], $_POST['password'])) {
+            global $secret;
 
-        if (isset($wefactapiurl) && isset($wefactapikey)) {
-            $wefact = do_wefact_auth($_POST['username'], $_POST['password']);
-            if ($wefact === FALSE) {
-                return FALSE;
-            }
-            if ($wefact !== -1) {
-                $do_local_auth = 0;
+            # only store if we have a secret.
+            if ($secret && isset($_POST['autologin']) && $_POST['autologin']) {
+                _store_auto_login(enc_secret(json_encode(array(
+                    'username' => $_POST['username'],
+                    'password' => $_POST['password']))));
             }
+            return true;
         }
-
-        if ($do_local_auth == 1) {
-            if (do_db_auth($_POST['username'], $_POST['password']) === FALSE) {
-                return FALSE;
-            }
-        }
-
-        $userinfo = get_user_info($_POST['username']);
-
-        set_logged_in($_POST['username']);
-        if (isset($userinfo['isadmin']) && $userinfo['isadmin'] == 1) {
-            set_is_adminuser();
-        }
-        return TRUE;
     }
-
-    return FALSE;
+    return false;
 }
 
-?>
+function _try_login($username, $password) {
+    global $wefactapiurl, $wefactapikey;
+
+    if (!valid_user($username)) {
+        return false;
+    }
+
+    $do_local_auth = true;
+
+    if (isset($wefactapiurl) && isset($wefactapikey)) {
+        $wefact = do_wefact_auth($username, $password);
+        if (false === $wefact ) {
+            return false;
+        }
+        if (-1 !== $wefact) {
+            $do_local_auth = false;
+        }
+    }
+
+    if ($do_local_auth && !do_db_auth($username, $password)) {
+        return false;
+    }
+
+    $user = get_user_info($username);
+    if (!$user) {
+        return false;
+    } else {
+        _set_current_user($username, (bool) $user['isadmin']);
+
+        if (session_id()) {
+            session_unset();
+            session_destroy();
+        }
+        session_start() or die('session failure: could not start session');
+        session_regenerate_id(true) or die('session failure: regenerated id failed');
+        session_unset();
+        $_SESSION['username'] = $username;
+
+        # requires session:
+        _check_csrf_token($user);
+        return true;
+    }
+}
+
+function _check_session() {
+    global $adminapikey, $adminapiips;
+
+    $is_ssl = isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off';
+    session_set_cookie_params(30*60, null, null, $is_ssl, true);
+    session_name('NSEDIT_SESSION');
+
+    if (isset($adminapikey) && '' !== $adminapikey && isset($adminapiips) && isset($_POST['adminapikey'])) {
+        if (false !== array_search($_SERVER['REMOTE_ADDR'], $adminapiips)
+            and $_POST['adminapikey'] === $adminapikey)
+        {
+            # Allow this request, fake that we're logged in as user.
+            return _set_current_user('admin', true, true, true);
+        }
+        else
+        {
+            header('Status: 403 Forbidden');
+            exit(0);
+        }
+    }
+
+    if (isset($_COOKIE['NSEDIT_SESSION'])) {
+        if (session_start() && isset($_SESSION['username'])) {
+            $user = get_user_info($_SESSION['username']);
+            if (!$user) {
+                session_destroy();
+                session_unset();
+            } else {
+                _set_current_user($_SESSION['username'], (bool) $user['isadmin']);
+                _check_csrf_token($user);
+                return;
+            }
+        }
+        // failed: remove cookie
+        _unset_cookie('NSEDIT_SESSION');
+    }
+
+    if (isset($_COOKIE['NSEDIT_AUTOLOGIN'])) {
+        $login = json_decode(dec_secret($_COOKIE['NSEDIT_AUTOLOGIN']), 1);
+        if ($login and isset($login['username']) and isset($login['password'])
+            and _try_login($login['username'], $login['password'])) {
+            _store_auto_login($_COOKIE['NSEDIT_AUTOLOGIN']); # reset cookie
+            return;
+        }
+
+        // failed: remove cookie
+        _unset_cookie('NSEDIT_AUTOLOGIN');
+    }
+}
+
+# auto load session if possible
+_check_session();
+
+function is_logged_in() {
+    global $current_user;
+    return (bool) $current_user;
+}
+
+# GET/HEAD requests only require a logged in user (they shouldn't trigger any
+# "writes"); all other requests require the X-CSRF-Token to be present.
+function is_csrf_safe() {
+    global $current_user;
+
+    switch ($_SERVER['REQUEST_METHOD']) {
+    case 'GET':
+    case 'HEAD':
+        return is_logged_in();
+    default:
+        return (bool) $current_user && (bool) $current_user['has_csrf_token'];
+    }
+}
+
+function is_apiuser() {
+    global $current_user;
+    return $current_user && (bool) $current_user['is_api'];
+}
+
+function is_adminuser() {
+    global $current_user;
+    return $current_user && (bool) $current_user['is_admin'];
+}
+
+function get_sess_user() {
+    global $current_user;
+    return $current_user ? $current_user['username'] : null;
+}
+
+function logout() {
+    @session_destroy();
+    @session_unset();
+    if (isset($_COOKIE['NSEDIT_AUTOLOGIN'])) {
+        _unset_cookie('NSEDIT_AUTOLOGIN');
+    }
+    if (isset($_COOKIE['NSEDIT_SESSION'])) {
+        _unset_cookie('NSEDIT_SESSION');
+    }
+}

includes/wefactauth.inc.php

@@ -78,5 +78,3 @@ function do_wefact_auth($u, $p) {
         return -1;
     }
 }
-
-?>

index.php

@@ -7,12 +7,11 @@ include_once('includes/misc.inc.php');
 if (isset($_GET['logout']) or isset($_POST['logout'])) {
     logout();
     header("Location: index.php");
+    exit(0);
 }
 
-if (!is_logged_in() and isset($_POST['formname']) && $_POST['formname'] == "loginform") {
-    if (try_login() === TRUE) {
-        set_logged_in($_POST['username']);
-    } else {
+if (!is_logged_in() and isset($_POST['formname']) and $_POST['formname'] === "loginform") {
+    if (!try_login()) {
         $errormsg = "Error while trying to authenticate you\n";
     }
 }
@@ -54,18 +53,28 @@ if (!is_logged_in()) {
             <table>
                 <tr>
                     <td class="label">Username:</td>
-                    <td><input id="username" type="text" name="username"/></td>
+                    <td><input id="username" type="text" name="username"></td>
                 </tr>
                 <tr>
                     <td class="label">Password:</td>
-                    <td><input type="password" name="password"/></td>
+                    <td><input type="password" name="password"></td>
                 </tr>
+                <?php
+                if (isset($secret) && $secret) {
+                ?>
+                <tr>
+                    <td class="label">Remember me:</td>
+                    <td><input type="checkbox" name="autologin" value="1"></td>
+                </tr>
+                <?php
+                }
+                ?>
                 <tr>
                     <td></td>
-                    <td><input type="submit" name="submit" value="Log me in!"/></td>
+                    <td><input type="submit" name="submit" value="Log me in!"></td>
                 </tr>
             </table>
-            <input type="hidden" name="formname" value="loginform"/>
+            <input type="hidden" name="formname" value="loginform">
         </form>
     </div>
 </div>
@@ -113,6 +122,21 @@ exit(0);
     <? } ?>
 </div>
 <script type="text/javascript">
+window.csrf_token = '<?php echo CSRF_TOKEN ?>';
+
+$(document).ready(function () {
+    function csrfSafeMethod(method) {
+        // these HTTP methods do not require CSRF protection
+        return (/^(GET|HEAD|OPTIONS|TRACE)$/.test(method));
+    }
+    $.ajaxSetup({
+        beforeSend: function(xhr, settings) {
+            if (!csrfSafeMethod(settings.type) && !this.crossDomain) {
+                xhr.setRequestHeader("X-CSRF-Token", window.csrf_token);
+            }
+        }
+    });
+});
 
 function displayDnssecIcon(zone) {
     if (zone.record.dnssec == true) {
@@ -670,4 +694,3 @@ $(document).ready(function () {
 </script>
 </body>
 </html>
-

users.php

@@ -4,7 +4,7 @@ include_once('includes/config.inc.php');
 include_once('includes/session.inc.php');
 include_once('includes/misc.inc.php');
 
-if (!is_logged_in()) {
+if (!is_csrf_safe()) {
     header('Status: 403');
     header('Location: ./index.php');
     jtable_respond(null, 'error', "Authentication required");
@@ -96,5 +96,3 @@ default:
     jtable_respond(null, 'error', 'Invalid action');
     break;
 }
-
-?>

zones.php

@@ -4,7 +4,7 @@ include_once('includes/config.inc.php');
 include_once('includes/session.inc.php');
 include_once('includes/misc.inc.php');
 
-if (!is_logged_in()) {
+if (!is_csrf_safe()) {
     header('Status: 403');
     header('Location: ./index.php');
     jtable_respond(null, 'error', "Authentication required");
@@ -605,5 +605,3 @@ default:
     jtable_respond(null, 'error', 'No such action');
     break;
 }
-
-?>