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 1999-2009 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         $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($check_referrer)) === 0
  64         || strpos(strtolower($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     sqgetGlobalVar('key',         $key,       SQ_COOKIE);
  97     sqgetGlobalVar('onetimepad',  $onetimepad,SQ_SESSION);
  98
  99     return OneTimePadDecrypt($key, $onetimepad);
 100 }
 101
 102 /**
 103  * Saves or updates user password information
 104  *
 105  * This function is used to update the password information that
 106  * SquirrelMail stores in the existing PHP session. It does NOT
 107  * modify the password stored in the authentication system used
 108  * by the IMAP server.
 109  *
 110  * This function must be called before any html output is started.
 111  * Direct access to password information is deprecated. The saved
 112  * password information is available only to the SquirrelMail script
 113  * that is called/executed AFTER the current one. If your script
 114  * needs access to the saved password after a sqauth_save_password()
 115  * call, use the returned OTP encrypted key.
 116  *
 117  * @param string $pass password
 118  *
 119  * @return string Password encrypted with OTP. In case the script
 120  *                wants to access the password information before
 121  *                the end of its execution.
 122  *
 123  * @since 1.5.1
 124  *
 125  */
 126 function sqauth_save_password($pass) {
 127     sqgetGlobalVar('base_uri',    $base_uri,   SQ_SESSION);
 128
 129     $onetimepad = OneTimePadCreate(strlen($pass));
 130     sqsession_register($onetimepad,'onetimepad');
 131     $key = OneTimePadEncrypt($pass, $onetimepad);
 132     sqsetcookie('key', $key, false, $base_uri);
 133     return $key;
 134 }
 135
 136 /**
 137  * Given the challenge from the server, supply the response using cram-md5 (See
 138  * RFC 2195 for details)
 139  *
 140  * @param string $username User ID
 141  * @param string $password User password supplied by User
 142  * @param string $challenge The challenge supplied by the server
 143  * @return string The response to be sent to the IMAP server
 144  * @since 1.4.0
 145  */
 146 function cram_md5_response ($username,$password,$challenge) {
 147     $challenge=base64_decode($challenge);
 148     $hash=bin2hex(hmac_md5($challenge,$password));
 149     $response=base64_encode($username . " " . $hash) . "\r\n";
 150     return $response;
 151 }
 152
 153 /**
 154  * Return Digest-MD5 response.
 155  * Given the challenge from the server, calculate and return the
 156  * response-string for digest-md5 authentication.  (See RFC 2831 for more
 157  * details)
 158  *
 159  * @param string $username User ID
 160  * @param string $password User password supplied by User
 161  * @param string $challenge The challenge supplied by the server
 162  * @param string $service The service name, usually 'imap'; it is used to
 163  *   define the digest-uri.
 164  * @param string $host The host name, usually the server's FQDN; it is used to
 165  *   define the digest-uri.
 166  * @param string $authz Authorization ID (since 1.5.2)
 167  * @return string The response to be sent to the IMAP server
 168  * @since 1.4.0
 169  */
 170 function digest_md5_response ($username,$password,$challenge,$service,$host,$authz='') {
 171     $result=digest_md5_parse_challenge($challenge);
 172     //FIXME we should check that $result contains the expected values that we use below
 173
 174     // verify server supports qop=auth
 175     // $qop = explode(",",$result['qop']);
 176     //if (!in_array("auth",$qop)) {
 177     // rfc2831: client MUST fail if no qop methods supported
 178     // return false;
 179     //}
 180     $cnonce = base64_encode(bin2hex(hmac_md5(microtime())));
 181     $ncount = "00000001";
 182
 183     /* This can be auth (authentication only), auth-int (integrity protection), or
 184        auth-conf (confidentiality protection).  Right now only auth is supported.
 185        DO NOT CHANGE THIS VALUE */
 186     $qop_value = "auth";
 187
 188     $digest_uri_value = $service . '/' . $host;
 189
 190     // build the $response_value
 191     //FIXME This will probably break badly if a server sends more than one realm
 192     $string_a1 = utf8_encode($username).":";
 193     $string_a1 .= utf8_encode($result['realm']).":";
 194     $string_a1 .= utf8_encode($password);
 195     $string_a1 = hmac_md5($string_a1);
 196     $A1 = $string_a1 . ":" . $result['nonce'] . ":" . $cnonce;
 197     if(!empty($authz)) {
 198         $A1 .= ":" . utf8_encode($authz);
 199     }
 200     $A1 = bin2hex(hmac_md5($A1));
 201     $A2 = "AUTHENTICATE:$digest_uri_value";
 202     // If qop is auth-int or auth-conf, A2 gets a little extra
 203     if ($qop_value != 'auth') {
 204         $A2 .= ':00000000000000000000000000000000';
 205     }
 206     $A2 = bin2hex(hmac_md5($A2));
 207
 208     $string_response = $result['nonce'] . ':' . $ncount . ':' . $cnonce . ':' . $qop_value;
 209     $response_value = bin2hex(hmac_md5($A1.":".$string_response.":".$A2));
 210
 211     $reply = 'charset=utf-8,username="' . $username . '",realm="' . $result["realm"] . '",';
 212     $reply .= 'nonce="' . $result['nonce'] . '",nc=' . $ncount . ',cnonce="' . $cnonce . '",';
 213     $reply .= "digest-uri=\"$digest_uri_value\",response=$response_value";
 214     $reply .= ',qop=' . $qop_value;
 215     if(!empty($authz)) {
 216         $reply .= ',authzid=' . $authz;
 217     }
 218     $reply = base64_encode($reply);
 219     return $reply . "\r\n";
 220
 221 }
 222
 223 /**
 224  * Parse Digest-MD5 challenge.
 225  * This function parses the challenge sent during DIGEST-MD5 authentication and
 226  * returns an array. See the RFC for details on what's in the challenge string.
 227  *
 228  * @param string $challenge Digest-MD5 Challenge
 229  * @return array Digest-MD5 challenge decoded data
 230  * @since 1.4.0
 231  */
 232 function digest_md5_parse_challenge($challenge) {
 233     $challenge=base64_decode($challenge);
 234     $parsed = array();
 235     while (!empty($challenge)) {
 236         if ($challenge{0} == ',') { // First char is a comma, must not be 1st time through loop
 237             $challenge=substr($challenge,1);
 238         }
 239         $key=explode('=',$challenge,2);
 240         $challenge=$key[1];
 241         $key=$key[0];
 242         if ($challenge{0} == '"') {
 243             // We're in a quoted value
 244             // Drop the first quote, since we don't care about it
 245             $challenge=substr($challenge,1);
 246             // Now explode() to the next quote, which is the end of our value
 247             $val=explode('"',$challenge,2);
 248             $challenge=$val[1]; // The rest of the challenge, work on it in next iteration of loop
 249             $value=explode(',',$val[0]);
 250             // Now, for those quoted values that are only 1 piece..
 251             if (sizeof($value) == 1) {
 252                 $value=$value[0];  // Convert to non-array
 253             }
 254         } else {
 255             // We're in a "simple" value - explode to next comma
 256             $val=explode(',',$challenge,2);
 257             if (isset($val[1])) {
 258                 $challenge=$val[1];
 259             } else {
 260                 unset($challenge);
 261             }
 262             $value=$val[0];
 263         }
 264         $parsed["$key"]=$value;
 265     } // End of while loop
 266     return $parsed;
 267 }
 268
 269 /**
 270  * Creates a HMAC digest that can be used for auth purposes
 271  * See RFCs 2104, 2617, 2831
 272  * Uses mhash() extension if available
 273  *
 274  * @param string $data Data to apply hash function to.
 275  * @param string $key Optional key, which, if supplied, will be used to
 276  * calculate data's HMAC.
 277  * @return string HMAC Digest string
 278  * @since 1.4.0
 279  */
 280 function hmac_md5($data, $key='') {
 281     if (extension_loaded('mhash')) {
 282         if ($key== '') {
 283             $mhash=mhash(MHASH_MD5,$data);
 284         } else {
 285             $mhash=mhash(MHASH_MD5,$data,$key);
 286         }
 287         return $mhash;
 288     }
 289     if (!$key) {
 290         return pack('H*',md5($data));
 291     }
 292     $key = str_pad($key,64,chr(0x00));
 293     if (strlen($key) > 64) {
 294         $key = pack("H*",md5($key));
 295     }
 296     $k_ipad =  $key ^ str_repeat(chr(0x36), 64) ;
 297     $k_opad =  $key ^ str_repeat(chr(0x5c), 64) ;
 298     /* Heh, let's get recursive. */
 299     $hmac=hmac_md5($k_opad . pack("H*",md5($k_ipad . $data)) );
 300     return $hmac;
 301 }
 302
 303 /**
 304  * Fillin user and password based on SMTP auth settings.
 305  *
 306  * @param string $user Reference to SMTP username
 307  * @param string $pass Reference to SMTP password (unencrypted)
 308  * @since 1.4.11
 309  */
 310 function get_smtp_user(&$user, &$pass) {
 311     global $username, $smtp_auth_mech,
 312            $smtp_sitewide_user, $smtp_sitewide_pass;
 313
 314     if ($smtp_auth_mech == 'none') {
 315         $user = '';
 316         $pass = '';
 317     } elseif ( isset($smtp_sitewide_user) && isset($smtp_sitewide_pass) &&
 318                !empty($smtp_sitewide_user)) {
 319         $user = $smtp_sitewide_user;
 320         $pass = $smtp_sitewide_pass;
 321     } else {
 322         $user = $username;
 323         $pass = sqauth_read_password();
 324     }
 325
 326     // plugin authors note: override $user or $pass by
 327     // directly changing the arguments array contents
 328     // in your plugin e.g., $args[0] = 'new_username';
 329     //
 330     $temp = array(&$user, &$pass);
 331     do_hook('smtp_auth', $temp);
 332 }