src/Util/HTTPSignature.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2021, the Friendica project
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Util;
  23
  24 use Friendica\Core\Logger;
  25 use Friendica\Database\Database;
  26 use Friendica\Database\DBA;
  27 use Friendica\DI;
  28 use Friendica\Model\APContact;
  29 use Friendica\Model\Contact;
  30 use Friendica\Model\User;
  31 use Friendica\Network\CurlResult;
  32 use Friendica\Network\IHTTPResult;
  33
  34 /**
  35  * Implements HTTP Signatures per draft-cavage-http-signatures-07.
  36  *
  37  * Ported from Hubzilla: https://framagit.org/hubzilla/core/blob/master/Zotlabs/Web/HTTPSig.php
  38  *
  39  * Other parts of the code for HTTP signing are taken from the Osada project.
  40  * https://framagit.org/macgirvin/osada
  41  *
  42  * @see https://tools.ietf.org/html/draft-cavage-http-signatures-07
  43  */
  44
  45 class HTTPSignature
  46 {
  47         // See draft-cavage-http-signatures-08
  48         /**
  49          * Verifies a magic request
  50          *
  51          * @param $key
  52          *
  53          * @return array with verification data
  54          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
  55          */
  56         public static function verifyMagic($key)
  57         {
  58                 $headers   = null;
  59                 $spoofable = false;
  60                 $result = [
  61                         'signer'         => '',
  62                         'header_signed'  => false,
  63                         'header_valid'   => false
  64                 ];
  65
  66                 // Decide if $data arrived via controller submission or curl.
  67                 $headers = [];
  68                 $headers['(request-target)'] = strtolower($_SERVER['REQUEST_METHOD']).' '.$_SERVER['REQUEST_URI'];
  69
  70                 foreach ($_SERVER as $k => $v) {
  71                         if (strpos($k, 'HTTP_') === 0) {
  72                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
  73                                 $headers[$field] = $v;
  74                         }
  75                 }
  76
  77                 $sig_block = null;
  78
  79                 $sig_block = self::parseSigheader($headers['authorization']);
  80
  81                 if (!$sig_block) {
  82                         Logger::log('no signature provided.');
  83                         return $result;
  84                 }
  85
  86                 $result['header_signed'] = true;
  87
  88                 $signed_headers = $sig_block['headers'];
  89                 if (!$signed_headers) {
  90                         $signed_headers = ['date'];
  91                 }
  92
  93                 $signed_data = '';
  94                 foreach ($signed_headers as $h) {
  95                         if (array_key_exists($h, $headers)) {
  96                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
  97                         }
  98                         if (strpos($h, '.')) {
  99                                 $spoofable = true;
 100                         }
 101                 }
 102
 103                 $signed_data = rtrim($signed_data, "\n");
 104
 105                 $algorithm = 'sha512';
 106
 107                 if ($key && function_exists($key)) {
 108                         $result['signer'] = $sig_block['keyId'];
 109                         $key = $key($sig_block['keyId']);
 110                 }
 111
 112                 Logger::log('Got keyID ' . $sig_block['keyId'], Logger::DEBUG);
 113
 114                 if (!$key) {
 115                         return $result;
 116                 }
 117
 118                 $x = Crypto::rsaVerify($signed_data, $sig_block['signature'], $key, $algorithm);
 119
 120                 Logger::log('verified: ' . $x, Logger::DEBUG);
 121
 122                 if (!$x) {
 123                         return $result;
 124                 }
 125
 126                 if (!$spoofable) {
 127                         $result['header_valid'] = true;
 128                 }
 129
 130                 return $result;
 131         }
 132
 133         /**
 134          * @param array   $head
 135          * @param string  $prvkey
 136          * @param string  $keyid (optional, default 'Key')
 137          *
 138          * @return array
 139          */
 140         public static function createSig($head, $prvkey, $keyid = 'Key')
 141         {
 142                 $return_headers = [];
 143
 144                 $alg = 'sha512';
 145                 $algorithm = 'rsa-sha512';
 146
 147                 $x = self::sign($head, $prvkey, $alg);
 148
 149                 $headerval = 'keyId="' . $keyid . '",algorithm="' . $algorithm
 150                         . '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
 151
 152                 $sighead = 'Authorization: Signature ' . $headerval;
 153
 154                 if ($head) {
 155                         foreach ($head as $k => $v) {
 156                                 $return_headers[] = $k . ': ' . $v;
 157                         }
 158                 }
 159
 160                 $return_headers[] = $sighead;
 161
 162                 return $return_headers;
 163         }
 164
 165         /**
 166          * @param array  $head
 167          * @param string $prvkey
 168          * @param string $alg (optional) default 'sha256'
 169          *
 170          * @return array
 171          */
 172         private static function sign($head, $prvkey, $alg = 'sha256')
 173         {
 174                 $ret = [];
 175                 $headers = '';
 176                 $fields  = '';
 177
 178                 foreach ($head as $k => $v) {
 179                         $headers .= strtolower($k) . ': ' . trim($v) . "\n";
 180                         if ($fields) {
 181                                 $fields .= ' ';
 182                         }
 183                         $fields .= strtolower($k);
 184                 }
 185                 // strip the trailing linefeed
 186                 $headers = rtrim($headers, "\n");
 187
 188                 $sig = base64_encode(Crypto::rsaSign($headers, $prvkey, $alg));
 189
 190                 $ret['headers']   = $fields;
 191                 $ret['signature'] = $sig;
 192
 193                 return $ret;
 194         }
 195
 196         /**
 197          * @param string $header
 198          * @return array associative array with
 199          *   - \e string \b keyID
 200          *   - \e string \b created
 201          *   - \e string \b expires
 202          *   - \e string \b algorithm
 203          *   - \e array  \b headers
 204          *   - \e string \b signature
 205          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 206          */
 207         public static function parseSigheader($header)
 208         {
 209                 // Remove obsolete folds
 210                 $header = preg_replace('/\n\s+/', ' ', $header);
 211
 212                 $token = "[!#$%&'*+.^_`|~0-9A-Za-z-]";
 213
 214                 $quotedString = '"(?:\\\\.|[^"\\\\])*"';
 215
 216                 $regex = "/($token+)=($quotedString|$token+)/ism";
 217
 218                 $matches = [];
 219                 preg_match_all($regex, $header, $matches, PREG_SET_ORDER);
 220
 221                 $headers = [];
 222                 foreach ($matches as $match) {
 223                         $headers[$match[1]] = trim($match[2] ?: $match[3], '"');
 224                 }
 225
 226                 // if the header is encrypted, decrypt with (default) site private key and continue
 227                 if (!empty($headers['iv'])) {
 228                         $header = self::decryptSigheader($headers, DI::config()->get('system', 'prvkey'));
 229                         return self::parseSigheader($header);
 230                 }
 231
 232                 $return = [
 233                         'keyId'     => $headers['keyId'] ?? '',
 234                         'algorithm' => $headers['algorithm'] ?? 'rsa-sha256',
 235                         'created'   => $headers['created'] ?? null,
 236                         'expires'   => $headers['expires'] ?? null,
 237                         'headers'   => explode(' ', $headers['headers'] ?? ''),
 238                         'signature' => base64_decode(preg_replace('/\s+/', '', $headers['signature'] ?? '')),
 239                 ];
 240
 241                 if (!empty($return['signature']) && !empty($return['algorithm']) && empty($return['headers'])) {
 242                         $return['headers'] = ['date'];
 243                 }
 244
 245                 return $return;
 246         }
 247
 248         /**
 249          * @param array  $headers Signature headers
 250          * @param string $prvkey  The site private key
 251          * @return string Decrypted signature string
 252          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 253          */
 254         private static function decryptSigheader(array $headers, string $prvkey)
 255         {
 256                 if (!empty($headers['iv']) && !empty($headers['key']) && !empty($headers['data'])) {
 257                         return Crypto::unencapsulate($headers, $prvkey);
 258                 }
 259
 260                 return '';
 261         }
 262
 263         /*
 264          * Functions for ActivityPub
 265          */
 266
 267         /**
 268          * Transmit given data to a target for a user
 269          *
 270          * @param array   $data   Data that is about to be send
 271          * @param string  $target The URL of the inbox
 272          * @param integer $uid    User id of the sender
 273          *
 274          * @return boolean Was the transmission successful?
 275          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 276          */
 277         public static function transmit($data, $target, $uid)
 278         {
 279                 $owner = User::getOwnerDataById($uid);
 280
 281                 if (!$owner) {
 282                         return;
 283                 }
 284
 285                 $content = json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
 286
 287                 // Header data that is about to be signed.
 288                 $host = parse_url($target, PHP_URL_HOST);
 289                 $path = parse_url($target, PHP_URL_PATH);
 290                 $digest = 'SHA-256=' . base64_encode(hash('sha256', $content, true));
 291                 $content_length = strlen($content);
 292                 $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 293
 294                 $headers = [
 295                         'Date' => $date,
 296                         'Content-Length' => $content_length,
 297                         'Digest' => $digest,
 298                         'Host' => $host
 299                 ];
 300
 301                 $signed_data = "(request-target): post " . $path . "\ndate: ". $date . "\ncontent-length: " . $content_length . "\ndigest: " . $digest . "\nhost: " . $host;
 302
 303                 $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 304
 305                 $headers['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date content-length digest host",signature="' . $signature . '"';
 306
 307                 $headers['Content-Type'] = 'application/activity+json';
 308
 309                 $postResult = DI::httpRequest()->post($target, $content, $headers);
 310                 $return_code = $postResult->getReturnCode();
 311
 312                 Logger::log('Transmit to ' . $target . ' returned ' . $return_code, Logger::DEBUG);
 313
 314                 $success = ($return_code >= 200) && ($return_code <= 299);
 315
 316                 self::setInboxStatus($target, $success);
 317
 318                 return $success;
 319         }
 320
 321         /**
 322          * Set the delivery status for a given inbox
 323          *
 324          * @param string  $url     The URL of the inbox
 325          * @param boolean $success Transmission status
 326          * @param boolean $shared  The inbox is a shared inbox
 327          */
 328         static public function setInboxStatus($url, $success, $shared = false)
 329         {
 330                 $now = DateTimeFormat::utcNow();
 331
 332                 $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 333                 if (!DBA::isResult($status)) {
 334                         DBA::insert('inbox-status', ['url' => $url, 'created' => $now, 'shared' => $shared], Database::INSERT_IGNORE);
 335                         $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 336                 }
 337
 338                 if ($success) {
 339                         $fields = ['success' => $now];
 340                 } else {
 341                         $fields = ['failure' => $now];
 342                 }
 343
 344                 if ($status['failure'] > DBA::NULL_DATETIME) {
 345                         $new_previous_stamp = strtotime($status['failure']);
 346                         $old_previous_stamp = strtotime($status['previous']);
 347
 348                         // Only set "previous" with at least one day difference.
 349                         // We use this to assure to not accidentally archive too soon.
 350                         if (($new_previous_stamp - $old_previous_stamp) >= 86400) {
 351                                 $fields['previous'] = $status['failure'];
 352                         }
 353                 }
 354
 355                 if (!$success) {
 356                         if ($status['success'] <= DBA::NULL_DATETIME) {
 357                                 $stamp1 = strtotime($status['created']);
 358                         } else {
 359                                 $stamp1 = strtotime($status['success']);
 360                         }
 361
 362                         $stamp2 = strtotime($now);
 363                         $previous_stamp = strtotime($status['previous']);
 364
 365                         // Archive the inbox when there had been failures for five days.
 366                         // Additionally ensure that at least one previous attempt has to be in between.
 367                         if ((($stamp2 - $stamp1) >= 86400 * 5) && ($previous_stamp > $stamp1)) {
 368                                 $fields['archive'] = true;
 369                         }
 370                 } else {
 371                         $fields['archive'] = false;
 372                 }
 373
 374                 DBA::update('inbox-status', $fields, ['url' => $url]);
 375         }
 376
 377         /**
 378          * Fetches JSON data for a user
 379          *
 380          * @param string  $request request url
 381          * @param integer $uid     User id of the requester
 382          *
 383          * @return array JSON array
 384          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 385          */
 386         public static function fetch($request, $uid)
 387         {
 388                 $curlResult = self::fetchRaw($request, $uid);
 389
 390                 if (empty($curlResult)) {
 391                         return false;
 392                 }
 393
 394                 if (!$curlResult->isSuccess() || empty($curlResult->getBody())) {
 395                         return false;
 396                 }
 397
 398                 $content = json_decode($curlResult->getBody(), true);
 399                 if (empty($content) || !is_array($content)) {
 400                         return false;
 401                 }
 402
 403                 return $content;
 404         }
 405
 406         /**
 407          * Fetches raw data for a user
 408          *
 409          * @param string  $request request url
 410          * @param integer $uid     User id of the requester
 411          * @param boolean $binary  TRUE if asked to return binary results (file download) (default is "false")
 412          * @param array   $opts    (optional parameters) assoziative array with:
 413          *                         'accept_content' => supply Accept: header with 'accept_content' as the value
 414          *                         'timeout' => int Timeout in seconds, default system config value or 60 seconds
 415          *                         'nobody' => only return the header
 416          *                         'cookiejar' => path to cookie jar file
 417          *
 418          * @return IHTTPResult CurlResult
 419          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 420          */
 421         public static function fetchRaw($request, $uid = 0, $opts = ['accept_content' => ['application/activity+json', 'application/ld+json']])
 422         {
 423                 $header = [];
 424
 425                 if (!empty($uid)) {
 426                         $owner = User::getOwnerDataById($uid);
 427                         if (!$owner) {
 428                                 return;
 429                         }
 430                 } else {
 431                         $owner = User::getSystemAccount();
 432                         if (!$owner) {
 433                                 return;
 434                         }
 435                 }
 436
 437                 if (!empty($owner['uprvkey'])) {
 438                         // Header data that is about to be signed.
 439                         $host = parse_url($request, PHP_URL_HOST);
 440                         $path = parse_url($request, PHP_URL_PATH);
 441                         $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 442
 443                         $header['Date'] = $date;
 444                         $header['Host'] = $host;
 445
 446                         $signed_data = "(request-target): get " . $path . "\ndate: ". $date . "\nhost: " . $host;
 447
 448                         $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 449
 450                         $header['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date host",signature="' . $signature . '"';
 451                 }
 452
 453                 $curl_opts = $opts;
 454                 $curl_opts['header'] = $header;
 455
 456                 if (!empty($opts['nobody'])) {
 457                         $curlResult = DI::httpRequest()->head($request, $curl_opts);
 458                 } else {
 459                         $curlResult = DI::httpRequest()->get($request, $curl_opts);
 460                 }
 461                 $return_code = $curlResult->getReturnCode();
 462
 463                 Logger::log('Fetched for user ' . $uid . ' from ' . $request . ' returned ' . $return_code, Logger::DEBUG);
 464
 465                 return $curlResult;
 466         }
 467
 468         /**
 469          * Gets a signer from a given HTTP request
 470          *
 471          * @param $content
 472          * @param $http_headers
 473          *
 474          * @return string Signer
 475          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 476          */
 477         public static function getSigner($content, $http_headers)
 478         {
 479                 if (empty($http_headers['HTTP_SIGNATURE'])) {
 480                         Logger::info('No HTTP_SIGNATURE header');
 481                         return false;
 482                 }
 483
 484                 if (!empty($content)) {
 485                         $object = json_decode($content, true);
 486                         if (empty($object)) {
 487                                 Logger::info('No object');
 488                                 return false;
 489                         }
 490
 491                         $actor = JsonLD::fetchElement($object, 'actor', 'id');
 492                 } else {
 493                         $actor = '';
 494                 }
 495
 496                 $headers = [];
 497                 $headers['(request-target)'] = strtolower($http_headers['REQUEST_METHOD']) . ' ' . parse_url($http_headers['REQUEST_URI'], PHP_URL_PATH);
 498
 499                 // First take every header
 500                 foreach ($http_headers as $k => $v) {
 501                         $field = str_replace('_', '-', strtolower($k));
 502                         $headers[$field] = $v;
 503                 }
 504
 505                 // Now add every http header
 506                 foreach ($http_headers as $k => $v) {
 507                         if (strpos($k, 'HTTP_') === 0) {
 508                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
 509                                 $headers[$field] = $v;
 510                         }
 511                 }
 512
 513                 $sig_block = self::parseSigHeader($http_headers['HTTP_SIGNATURE']);
 514
 515                 if (empty($sig_block) || empty($sig_block['headers']) || empty($sig_block['keyId'])) {
 516                         Logger::info('No headers or keyId');
 517                         return false;
 518                 }
 519
 520                 $signed_data = '';
 521                 foreach ($sig_block['headers'] as $h) {
 522                         if (array_key_exists($h, $headers)) {
 523                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
 524                         }
 525                 }
 526                 $signed_data = rtrim($signed_data, "\n");
 527
 528                 if (empty($signed_data)) {
 529                         Logger::info('Signed data is empty');
 530                         return false;
 531                 }
 532
 533                 $algorithm = null;
 534
 535                 // Wildcard value where signing algorithm should be derived from keyId
 536                 // @see https://tools.ietf.org/html/draft-ietf-httpbis-message-signatures-00#section-4.1
 537                 // Defaulting to SHA256 as it seems to be the prevalent implementation
 538                 // @see https://arewehs2019yet.vpzom.click
 539                 if ($sig_block['algorithm'] === 'hs2019') {
 540                         $algorithm = 'sha256';
 541                 }
 542
 543                 if ($sig_block['algorithm'] === 'rsa-sha256') {
 544                         $algorithm = 'sha256';
 545                 }
 546
 547                 if ($sig_block['algorithm'] === 'rsa-sha512') {
 548                         $algorithm = 'sha512';
 549                 }
 550
 551                 if (empty($algorithm)) {
 552                         Logger::info('No alagorithm');
 553                         return false;
 554                 }
 555
 556                 $key = self::fetchKey($sig_block['keyId'], $actor);
 557                 if (empty($key)) {
 558                         Logger::info('Empty key');
 559                         return false;
 560                 }
 561
 562                 if (!empty($key['url']) && !empty($key['type']) && ($key['type'] == 'Tombstone')) {
 563                         Logger::info('Actor is a tombstone', ['key' => $key]);
 564
 565                         if (!Contact::isLocal($key['url'])) {
 566                                 // We now delete everything that we possibly knew from this actor
 567                                 Contact::deleteContactByUrl($key['url']);
 568                         }
 569                         return null;
 570                 }
 571
 572                 if (empty($key['pubkey'])) {
 573                         Logger::info('Empty pubkey');
 574                         return false;
 575                 }
 576
 577                 if (!Crypto::rsaVerify($signed_data, $sig_block['signature'], $key['pubkey'], $algorithm)) {
 578                         Logger::info('Verification failed');
 579                         return false;
 580                 }
 581
 582                 $hasGoodSignedContent = false;
 583
 584                 // Check the digest when it is part of the signed data
 585                 if (!empty($content) && in_array('digest', $sig_block['headers'])) {
 586                         $digest = explode('=', $headers['digest'], 2);
 587                         if ($digest[0] === 'SHA-256') {
 588                                 $hashalg = 'sha256';
 589                         }
 590                         if ($digest[0] === 'SHA-512') {
 591                                 $hashalg = 'sha512';
 592                         }
 593
 594                         /// @todo add all hashes from the rfc
 595
 596                         if (!empty($hashalg) && base64_encode(hash($hashalg, $content, true)) != $digest[1]) {
 597                                 Logger::info('Digest does not match');
 598                                 return false;
 599                         }
 600
 601                         $hasGoodSignedContent = true;
 602                 }
 603
 604                 //  Check if the signed date field is in an acceptable range
 605                 if (in_array('date', $sig_block['headers'])) {
 606                         $diff = abs(strtotime($headers['date']) - time());
 607                         if ($diff > 300) {
 608                                 Logger::log("Header date '" . $headers['date'] . "' is with " . $diff . " seconds out of the 300 second frame. The signature is invalid.");
 609                                 return false;
 610                         }
 611                         $hasGoodSignedContent = true;
 612                 }
 613
 614                 // Check the content-length when it is part of the signed data
 615                 if (in_array('content-length', $sig_block['headers'])) {
 616                         if (strlen($content) != $headers['content-length']) {
 617                                 Logger::info('Content length does not match');
 618                                 return false;
 619                         }
 620                 }
 621
 622                 // Ensure that the authentication had been done with some content
 623                 // Without this check someone could authenticate with fakeable data
 624                 if (!$hasGoodSignedContent) {
 625                         Logger::info('No good signed content');
 626                         return false;
 627                 }
 628
 629                 return $key['url'];
 630         }
 631
 632         /**
 633          * fetches a key for a given id and actor
 634          *
 635          * @param $id
 636          * @param $actor
 637          *
 638          * @return array with actor url and public key
 639          * @throws \Exception
 640          */
 641         private static function fetchKey($id, $actor)
 642         {
 643                 $url = (strpos($id, '#') ? substr($id, 0, strpos($id, '#')) : $id);
 644
 645                 $profile = APContact::getByURL($url);
 646                 if (!empty($profile)) {
 647                         Logger::info('Taking key from id', ['id' => $id]);
 648                         return ['url' => $url, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 649                 } elseif ($url != $actor) {
 650                         $profile = APContact::getByURL($actor);
 651                         if (!empty($profile)) {
 652                                 Logger::info('Taking key from actor', ['actor' => $actor]);
 653                                 return ['url' => $actor, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 654                         }
 655                 }
 656
 657                 Logger::notice('Key could not be fetched', ['url' => $url, 'actor' => $actor]);
 658                 return false;
 659         }
 660 }