functions/auth.php

   1 <?php
   2
   3 /**
   4  * auth.php
   5  *
   6  * Contains functions used to do authentication.
   7  *
   8  * Dependencies:
   9  *  functions/global.php
  10  *  functions/strings.php.
  11  *
  12  * @copyright 1999-2011 The SquirrelMail Project Team
  13  * @license http://opensource.org/licenses/gpl-license.php GNU Public License
  14  * @version $Id$
  15  * @package squirrelmail
  16  */
  17
  18
  19 /**
  20  * Detect whether user is logged in
  21  *
  22  * Function is similar to is_logged_in() function. If user is logged in, function
  23  * returns true. If user is not logged in or session is expired, function saves $_POST
  24  * and PAGE_NAME in session and returns false. POST information is saved in
  25  * 'session_expired_post' variable, PAGE_NAME is saved in 'session_expired_location'.
  26  *
  27  * This function optionally checks the referrer of this page request.  If the
  28  * administrator wants to impose a check that the referrer of this page request
  29  * is another page on the same domain (otherwise, the page request is likely
  30  * the result of a XSS or phishing attack), then they need to specify the
  31  * acceptable referrer domain in a variable named $check_referrer in
  32  * config/config.php (or the configuration tool) for which the value is
  33  * usually the same as the $domain setting (for example:
  34  *    $check_referrer = 'example.com';
  35  * However, in some cases (where proxy servers are in use, etc.), the
  36  * acceptable referrer might be different.  If $check_referrer is set to
  37  * "###DOMAIN###", then the current value of $domain is used (useful in
  38  * situations where $domain might change at runtime (when using the Login
  39  * Manager plugin to host multiple domains with one SquirrelMail installation,
  40  * for example)):
  41  *    $check_referrer = '###DOMAIN###';
  42  * NOTE HOWEVER, that referrer checks are not foolproof - they can be spoofed
  43  * by browsers, and some browsers intentionally don't send them, in which
  44  * case SquirrelMail silently ignores referrer checks.
  45  *
  46  * Script that uses this function instead of is_logged_in() function, must handle user
  47  * level messages.
  48  * @return boolean
  49  * @since 1.5.1
  50  */
  51 function sqauth_is_logged_in() {
  52
  53     global $check_referrer, $domain;
  54     if (!sqgetGlobalVar('HTTP_REFERER', $referrer, SQ_SERVER)) $referrer = '';
  55     if ($check_referrer == '###DOMAIN###') $check_referrer = $domain;
  56     if (!empty($check_referrer)) {
  57         $ssl_check_referrer = 'https://' . $check_referrer;
  58         $plain_check_referrer = 'http://' . $check_referrer;
  59     }
  60     if (sqsession_is_registered('user_is_logged_in')
  61      && (!$check_referrer || empty($referrer)
  62       || ($check_referrer && !empty($referrer)
  63        && (strpos(strtolower($referrer), strtolower($plain_check_referrer)) === 0
  64         || strpos(strtolower($referrer), strtolower($ssl_check_referrer)) === 0)))) {
  65         return true;
  66     }
  67
  68     //  First we store some information in the new session to prevent
  69     //  information-loss.
  70     $session_expired_post = $_POST;
  71     if (defined('PAGE_NAME'))
  72         $session_expired_location = PAGE_NAME;
  73     else
  74         $session_expired_location = '';
  75
  76     if (!sqsession_is_registered('session_expired_post')) {
  77         sqsession_register($session_expired_post,'session_expired_post');
  78     }
  79     if (!sqsession_is_registered('session_expired_location')) {
  80         sqsession_register($session_expired_location,'session_expired_location');
  81     }
  82
  83     session_write_close();
  84
  85     return false;
  86 }
  87
  88 /**
  89  * Reads and decodes stored user password information
  90  *
  91  * Direct access to password information is deprecated.
  92  * @return string password in plain text
  93  * @since 1.5.1
  94  */
  95 function sqauth_read_password() {
  96     global $currentHookName;
  97     if ($currentHookName == 'login_verified') global $key;
  98
  99     sqgetGlobalVar('key',         $key,       SQ_COOKIE);
 100     sqgetGlobalVar('onetimepad',  $onetimepad,SQ_SESSION);
 101
 102     return OneTimePadDecrypt($key, $onetimepad);
 103 }
 104
 105 /**
 106  * Saves or updates user password information
 107  *
 108  * This function is used to update the password information that
 109  * SquirrelMail stores in the existing PHP session. It does NOT
 110  * modify the password stored in the authentication system used
 111  * by the IMAP server.
 112  *
 113  * This function must be called before any html output is started.
 114  * Direct access to password information is deprecated. The saved
 115  * password information is available only to the SquirrelMail script
 116  * that is called/executed AFTER the current one. If your script
 117  * needs access to the saved password after a sqauth_save_password()
 118  * call, use the returned OTP encrypted key.
 119  *
 120  * @param string $pass password
 121  *
 122  * @return string Password encrypted with OTP. In case the script
 123  *                wants to access the password information before
 124  *                the end of its execution.
 125  *
 126  * @since 1.5.1
 127  *
 128  */
 129 function sqauth_save_password($pass) {
 130     sqgetGlobalVar('base_uri',    $base_uri,   SQ_SESSION);
 131
 132     $onetimepad = OneTimePadCreate(strlen($pass));
 133     sqsession_register($onetimepad,'onetimepad');
 134     $key = OneTimePadEncrypt($pass, $onetimepad);
 135     sqsetcookie('key', $key, false, $base_uri);
 136     return $key;
 137 }
 138
 139 /**
 140  * Given the challenge from the server, supply the response using cram-md5 (See
 141  * RFC 2195 for details)
 142  *
 143  * @param string $username User ID
 144  * @param string $password User password supplied by User
 145  * @param string $challenge The challenge supplied by the server
 146  * @return string The response to be sent to the IMAP server
 147  * @since 1.4.0
 148  */
 149 function cram_md5_response ($username,$password,$challenge) {
 150     $challenge=base64_decode($challenge);
 151     $hash=bin2hex(hmac_md5($challenge,$password));
 152     $response=base64_encode($username . " " . $hash) . "\r\n";
 153     return $response;
 154 }
 155
 156 /**
 157  * Return Digest-MD5 response.
 158  * Given the challenge from the server, calculate and return the
 159  * response-string for digest-md5 authentication.  (See RFC 2831 for more
 160  * details)
 161  *
 162  * @param string $username User ID
 163  * @param string $password User password supplied by User
 164  * @param string $challenge The challenge supplied by the server
 165  * @param string $service The service name, usually 'imap'; it is used to
 166  *   define the digest-uri.
 167  * @param string $host The host name, usually the server's FQDN; it is used to
 168  *   define the digest-uri.
 169  * @param string $authz Authorization ID (since 1.5.2)
 170  * @return string The response to be sent to the IMAP server
 171  * @since 1.4.0
 172  */
 173 function digest_md5_response ($username,$password,$challenge,$service,$host,$authz='') {
 174     $result=digest_md5_parse_challenge($challenge);
 175     //FIXME we should check that $result contains the expected values that we use below
 176
 177     // verify server supports qop=auth
 178     // $qop = explode(",",$result['qop']);
 179     //if (!in_array("auth",$qop)) {
 180     // rfc2831: client MUST fail if no qop methods supported
 181     // return false;
 182     //}
 183     $cnonce = base64_encode(bin2hex(hmac_md5(microtime())));
 184     $ncount = "00000001";
 185
 186     /* This can be auth (authentication only), auth-int (integrity protection), or
 187        auth-conf (confidentiality protection).  Right now only auth is supported.
 188        DO NOT CHANGE THIS VALUE */
 189     $qop_value = "auth";
 190
 191     $digest_uri_value = $service . '/' . $host;
 192
 193     // build the $response_value
 194     //FIXME This will probably break badly if a server sends more than one realm
 195     $string_a1 = utf8_encode($username).":";
 196     $string_a1 .= utf8_encode($result['realm']).":";
 197     $string_a1 .= utf8_encode($password);
 198     $string_a1 = hmac_md5($string_a1);
 199     $A1 = $string_a1 . ":" . $result['nonce'] . ":" . $cnonce;
 200     if(!empty($authz)) {
 201         $A1 .= ":" . utf8_encode($authz);
 202     }
 203     $A1 = bin2hex(hmac_md5($A1));
 204     $A2 = "AUTHENTICATE:$digest_uri_value";
 205     // If qop is auth-int or auth-conf, A2 gets a little extra
 206     if ($qop_value != 'auth') {
 207         $A2 .= ':00000000000000000000000000000000';
 208     }
 209     $A2 = bin2hex(hmac_md5($A2));
 210
 211     $string_response = $result['nonce'] . ':' . $ncount . ':' . $cnonce . ':' . $qop_value;
 212     $response_value = bin2hex(hmac_md5($A1.":".$string_response.":".$A2));
 213
 214     $reply = 'charset=utf-8,username="' . $username . '",realm="' . $result["realm"] . '",';
 215     $reply .= 'nonce="' . $result['nonce'] . '",nc=' . $ncount . ',cnonce="' . $cnonce . '",';
 216     $reply .= "digest-uri=\"$digest_uri_value\",response=$response_value";
 217     $reply .= ',qop=' . $qop_value;
 218     if(!empty($authz)) {
 219         $reply .= ',authzid=' . $authz;
 220     }
 221     $reply = base64_encode($reply);
 222     return $reply . "\r\n";
 223
 224 }
 225
 226 /**
 227  * Parse Digest-MD5 challenge.
 228  * This function parses the challenge sent during DIGEST-MD5 authentication and
 229  * returns an array. See the RFC for details on what's in the challenge string.
 230  *
 231  * @param string $challenge Digest-MD5 Challenge
 232  * @return array Digest-MD5 challenge decoded data
 233  * @since 1.4.0
 234  */
 235 function digest_md5_parse_challenge($challenge) {
 236     $challenge=base64_decode($challenge);
 237     $parsed = array();
 238     while (!empty($challenge)) {
 239         if ($challenge{0} == ',') { // First char is a comma, must not be 1st time through loop
 240             $challenge=substr($challenge,1);
 241         }
 242         $key=explode('=',$challenge,2);
 243         $challenge=$key[1];
 244         $key=$key[0];
 245         if ($challenge{0} == '"') {
 246             // We're in a quoted value
 247             // Drop the first quote, since we don't care about it
 248             $challenge=substr($challenge,1);
 249             // Now explode() to the next quote, which is the end of our value
 250             $val=explode('"',$challenge,2);
 251             $challenge=$val[1]; // The rest of the challenge, work on it in next iteration of loop
 252             $value=explode(',',$val[0]);
 253             // Now, for those quoted values that are only 1 piece..
 254             if (sizeof($value) == 1) {
 255                 $value=$value[0];  // Convert to non-array
 256             }
 257         } else {
 258             // We're in a "simple" value - explode to next comma
 259             $val=explode(',',$challenge,2);
 260             if (isset($val[1])) {
 261                 $challenge=$val[1];
 262             } else {
 263                 unset($challenge);
 264             }
 265             $value=$val[0];
 266         }
 267         $parsed["$key"]=$value;
 268     } // End of while loop
 269     return $parsed;
 270 }
 271
 272 /**
 273   * Creates a HMAC digest that can be used for authentication purposes
 274   * See RFCs 2104, 2617, 2831
 275   *
 276   * Uses PHP's Hash extension if available (enabled by default in PHP
 277   * 5.1.2+ - see http://www.php.net/manual/en/hash.requirements.php
 278   * or, if installed on earlier PHP versions, the PECL hash module -
 279   * see http://pecl.php.net/package/hash
 280   *
 281   * Otherwise, will attempt to use the Mhash extension - see
 282   * http://www.php.net/manual/en/mhash.requirements.php
 283   *
 284   * Finally, a fall-back custom implementation is used if none of
 285   * the above are available.
 286   *
 287   * @param string $data The data to be encoded/hashed
 288   * @param string $key The (shared) secret key that will be used
 289   *                    to build the keyed hash.  This argument is
 290   *                    technically optional, but only for internal
 291   *                    use (when the custom hash implementation is
 292   *                    being used) - external callers should always
 293   *                    specify a value for this argument.
 294   *
 295   * @return string The HMAC-MD5 digest string
 296   * @since 1.4.0
 297   *
 298   */
 299 function hmac_md5($data, $key='') {
 300
 301     // use PHP's native Hash extension if possible
 302     //
 303     if (function_exists('hash_hmac'))
 304         return pack('H*', hash_hmac('md5', $data, $key));
 305
 306
 307     // otherwise, use (obsolete) mhash extension if available
 308     //
 309     if (extension_loaded('mhash')) {
 310
 311         if ($key == '')
 312             $mhash = mhash(MHASH_MD5, $data);
 313         else
 314             $mhash = mhash(MHASH_MD5, $data, $key);
 315
 316         return $mhash;
 317     }
 318
 319
 320     // or, our own implementation...
 321     //
 322     if (!$key)
 323         return pack('H*', md5($data));
 324
 325     $key = str_pad($key, 64, chr(0x00));
 326
 327     if (strlen($key) > 64)
 328         $key = pack("H*", md5($key));
 329
 330     $k_ipad = $key ^ str_repeat(chr(0x36), 64);
 331     $k_opad = $key ^ str_repeat(chr(0x5c), 64);
 332
 333     $hmac = hmac_md5($k_opad . pack('H*', md5($k_ipad . $data)));
 334
 335     return $hmac;
 336
 337 }
 338
 339 /**
 340  * Fillin user and password based on SMTP auth settings.
 341  *
 342  * @param string $user Reference to SMTP username
 343  * @param string $pass Reference to SMTP password (unencrypted)
 344  * @since 1.4.11
 345  */
 346 function get_smtp_user(&$user, &$pass) {
 347     global $username, $smtp_auth_mech,
 348            $smtp_sitewide_user, $smtp_sitewide_pass;
 349
 350     if ($smtp_auth_mech == 'none') {
 351         $user = '';
 352         $pass = '';
 353     } elseif ( isset($smtp_sitewide_user) && isset($smtp_sitewide_pass) &&
 354                !empty($smtp_sitewide_user)) {
 355         $user = $smtp_sitewide_user;
 356         $pass = $smtp_sitewide_pass;
 357     } else {
 358         $user = $username;
 359         $pass = sqauth_read_password();
 360     }
 361
 362     // plugin authors note: override $user or $pass by
 363     // directly changing the arguments array contents
 364     // in your plugin e.g., $args[0] = 'new_username';
 365     //
 366     $temp = array(&$user, &$pass);
 367     do_hook('smtp_auth', $temp);
 368 }