src/Util/HTTPSignature.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2022, 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\HTTPClient\Client\HttpClientOptions;
  32
  33 /**
  34  * Implements HTTP Signatures per draft-cavage-http-signatures-07.
  35  *
  36  * Ported from Hubzilla: https://framagit.org/hubzilla/core/blob/master/Zotlabs/Web/HTTPSig.php
  37  *
  38  * Other parts of the code for HTTP signing are taken from the Osada project.
  39  * https://framagit.org/macgirvin/osada
  40  *
  41  * @see https://tools.ietf.org/html/draft-cavage-http-signatures-07
  42  */
  43
  44 class HTTPSignature
  45 {
  46         // See draft-cavage-http-signatures-08
  47         /**
  48          * Verifies a magic request
  49          *
  50          * @param $key
  51          *
  52          * @return array with verification data
  53          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
  54          */
  55         public static function verifyMagic($key)
  56         {
  57                 $headers   = null;
  58                 $spoofable = false;
  59                 $result = [
  60                         'signer'         => '',
  61                         'header_signed'  => false,
  62                         'header_valid'   => false
  63                 ];
  64
  65                 // Decide if $data arrived via controller submission or curl.
  66                 $headers = [];
  67                 $headers['(request-target)'] = strtolower(DI::args()->getMethod()).' '.$_SERVER['REQUEST_URI'];
  68
  69                 foreach ($_SERVER as $k => $v) {
  70                         if (strpos($k, 'HTTP_') === 0) {
  71                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
  72                                 $headers[$field] = $v;
  73                         }
  74                 }
  75
  76                 $sig_block = null;
  77
  78                 $sig_block = self::parseSigheader($headers['authorization']);
  79
  80                 if (!$sig_block) {
  81                         Logger::notice('no signature provided.');
  82                         return $result;
  83                 }
  84
  85                 $result['header_signed'] = true;
  86
  87                 $signed_headers = $sig_block['headers'];
  88                 if (!$signed_headers) {
  89                         $signed_headers = ['date'];
  90                 }
  91
  92                 $signed_data = '';
  93                 foreach ($signed_headers as $h) {
  94                         if (array_key_exists($h, $headers)) {
  95                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
  96                         }
  97                         if (strpos($h, '.')) {
  98                                 $spoofable = true;
  99                         }
 100                 }
 101
 102                 $signed_data = rtrim($signed_data, "\n");
 103
 104                 $algorithm = 'sha512';
 105
 106                 if ($key && function_exists($key)) {
 107                         $result['signer'] = $sig_block['keyId'];
 108                         $key = $key($sig_block['keyId']);
 109                 }
 110
 111                 Logger::info('Got keyID ' . $sig_block['keyId']);
 112
 113                 if (!$key) {
 114                         return $result;
 115                 }
 116
 117                 $x = Crypto::rsaVerify($signed_data, $sig_block['signature'], $key, $algorithm);
 118
 119                 Logger::info('verified: ' . $x);
 120
 121                 if (!$x) {
 122                         return $result;
 123                 }
 124
 125                 if (!$spoofable) {
 126                         $result['header_valid'] = true;
 127                 }
 128
 129                 return $result;
 130         }
 131
 132         /**
 133          * @param array   $head
 134          * @param string  $prvkey
 135          * @param string  $keyid (optional, default 'Key')
 136          *
 137          * @return array
 138          */
 139         public static function createSig($head, $prvkey, $keyid = 'Key')
 140         {
 141                 $return_headers = [];
 142                 if (!empty($head)) {
 143                         $return_headers = $head;
 144                 }
 145
 146                 $alg = 'sha512';
 147                 $algorithm = 'rsa-sha512';
 148
 149                 $x = self::sign($head, $prvkey, $alg);
 150
 151                 $headerval = 'keyId="' . $keyid . '",algorithm="' . $algorithm
 152                         . '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
 153
 154                 $return_headers['Authorization'] = ['Signature ' . $headerval];
 155
 156                 return $return_headers;
 157         }
 158
 159         /**
 160          * @param array  $head
 161          * @param string $prvkey
 162          * @param string $alg (optional) default 'sha256'
 163          *
 164          * @return array
 165          */
 166         private static function sign($head, $prvkey, $alg = 'sha256')
 167         {
 168                 $ret = [];
 169                 $headers = '';
 170                 $fields  = '';
 171
 172                 foreach ($head as $k => $v) {
 173                         if (is_array($v)) {
 174                                 $v = implode(', ', $v);
 175                         }
 176                         $headers .= strtolower($k) . ': ' . trim($v) . "\n";
 177                         if ($fields) {
 178                                 $fields .= ' ';
 179                         }
 180                         $fields .= strtolower($k);
 181                 }
 182                 // strip the trailing linefeed
 183                 $headers = rtrim($headers, "\n");
 184
 185                 $sig = base64_encode(Crypto::rsaSign($headers, $prvkey, $alg));
 186
 187                 $ret['headers']   = $fields;
 188                 $ret['signature'] = $sig;
 189
 190                 return $ret;
 191         }
 192
 193         /**
 194          * @param string $header
 195          * @return array associative array with
 196          *   - \e string \b keyID
 197          *   - \e string \b created
 198          *   - \e string \b expires
 199          *   - \e string \b algorithm
 200          *   - \e array  \b headers
 201          *   - \e string \b signature
 202          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 203          */
 204         public static function parseSigheader($header)
 205         {
 206                 // Remove obsolete folds
 207                 $header = preg_replace('/\n\s+/', ' ', $header);
 208
 209                 $token = "[!#$%&'*+.^_`|~0-9A-Za-z-]";
 210
 211                 $quotedString = '"(?:\\\\.|[^"\\\\])*"';
 212
 213                 $regex = "/($token+)=($quotedString|$token+)/ism";
 214
 215                 $matches = [];
 216                 preg_match_all($regex, $header, $matches, PREG_SET_ORDER);
 217
 218                 $headers = [];
 219                 foreach ($matches as $match) {
 220                         $headers[$match[1]] = trim($match[2] ?: $match[3], '"');
 221                 }
 222
 223                 // if the header is encrypted, decrypt with (default) site private key and continue
 224                 if (!empty($headers['iv'])) {
 225                         $header = self::decryptSigheader($headers, DI::config()->get('system', 'prvkey'));
 226                         return self::parseSigheader($header);
 227                 }
 228
 229                 $return = [
 230                         'keyId'     => $headers['keyId'] ?? '',
 231                         'algorithm' => $headers['algorithm'] ?? 'rsa-sha256',
 232                         'created'   => $headers['created'] ?? null,
 233                         'expires'   => $headers['expires'] ?? null,
 234                         'headers'   => explode(' ', $headers['headers'] ?? ''),
 235                         'signature' => base64_decode(preg_replace('/\s+/', '', $headers['signature'] ?? '')),
 236                 ];
 237
 238                 if (!empty($return['signature']) && !empty($return['algorithm']) && empty($return['headers'])) {
 239                         $return['headers'] = ['date'];
 240                 }
 241
 242                 return $return;
 243         }
 244
 245         /**
 246          * @param array  $headers Signature headers
 247          * @param string $prvkey  The site private key
 248          * @return string Decrypted signature string
 249          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 250          */
 251         private static function decryptSigheader(array $headers, string $prvkey)
 252         {
 253                 if (!empty($headers['iv']) && !empty($headers['key']) && !empty($headers['data'])) {
 254                         return Crypto::unencapsulate($headers, $prvkey);
 255                 }
 256
 257                 return '';
 258         }
 259
 260         /*
 261          * Functions for ActivityPub
 262          */
 263
 264         /**
 265          * Transmit given data to a target for a user
 266          *
 267          * @param array   $data   Data that is about to be send
 268          * @param string  $target The URL of the inbox
 269          * @param integer $uid    User id of the sender
 270          *
 271          * @return boolean Was the transmission successful?
 272          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 273          */
 274         public static function transmit($data, $target, $uid)
 275         {
 276                 $owner = User::getOwnerDataById($uid);
 277
 278                 if (!$owner) {
 279                         return;
 280                 }
 281
 282                 $content = json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
 283
 284                 // Header data that is about to be signed.
 285                 $host = parse_url($target, PHP_URL_HOST);
 286                 $path = parse_url($target, PHP_URL_PATH);
 287                 $digest = 'SHA-256=' . base64_encode(hash('sha256', $content, true));
 288                 $content_length = strlen($content);
 289                 $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 290
 291                 $headers = [
 292                         'Date' => $date,
 293                         'Content-Length' => $content_length,
 294                         'Digest' => $digest,
 295                         'Host' => $host
 296                 ];
 297
 298                 $signed_data = "(request-target): post " . $path . "\ndate: ". $date . "\ncontent-length: " . $content_length . "\ndigest: " . $digest . "\nhost: " . $host;
 299
 300                 $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 301
 302                 $headers['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date content-length digest host",signature="' . $signature . '"';
 303
 304                 $headers['Content-Type'] = 'application/activity+json';
 305
 306                 $postResult = DI::httpClient()->post($target, $content, $headers);
 307                 $return_code = $postResult->getReturnCode();
 308
 309                 Logger::info('Transmit to ' . $target . ' returned ' . $return_code);
 310
 311                 $success = ($return_code >= 200) && ($return_code <= 299);
 312
 313                 self::setInboxStatus($target, $success);
 314
 315                 return $success;
 316         }
 317
 318         /**
 319          * Set the delivery status for a given inbox
 320          *
 321          * @param string  $url     The URL of the inbox
 322          * @param boolean $success Transmission status
 323          * @param boolean $shared  The inbox is a shared inbox
 324          */
 325         static public function setInboxStatus($url, $success, $shared = false)
 326         {
 327                 $now = DateTimeFormat::utcNow();
 328
 329                 $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 330                 if (!DBA::isResult($status)) {
 331                         DBA::insert('inbox-status', ['url' => $url, 'created' => $now, 'shared' => $shared], Database::INSERT_IGNORE);
 332                         $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 333                 }
 334
 335                 if ($success) {
 336                         $fields = ['success' => $now];
 337                 } else {
 338                         $fields = ['failure' => $now];
 339                 }
 340
 341                 if ($status['failure'] > DBA::NULL_DATETIME) {
 342                         $new_previous_stamp = strtotime($status['failure']);
 343                         $old_previous_stamp = strtotime($status['previous']);
 344
 345                         // Only set "previous" with at least one day difference.
 346                         // We use this to assure to not accidentally archive too soon.
 347                         if (($new_previous_stamp - $old_previous_stamp) >= 86400) {
 348                                 $fields['previous'] = $status['failure'];
 349                         }
 350                 }
 351
 352                 if (!$success) {
 353                         if ($status['success'] <= DBA::NULL_DATETIME) {
 354                                 $stamp1 = strtotime($status['created']);
 355                         } else {
 356                                 $stamp1 = strtotime($status['success']);
 357                         }
 358
 359                         $stamp2 = strtotime($now);
 360                         $previous_stamp = strtotime($status['previous']);
 361
 362                         // Archive the inbox when there had been failures for five days.
 363                         // Additionally ensure that at least one previous attempt has to be in between.
 364                         if ((($stamp2 - $stamp1) >= 86400 * 5) && ($previous_stamp > $stamp1)) {
 365                                 $fields['archive'] = true;
 366                         }
 367                 } else {
 368                         $fields['archive'] = false;
 369                 }
 370
 371                 DBA::update('inbox-status', $fields, ['url' => $url]);
 372         }
 373
 374         /**
 375          * Fetches JSON data for a user
 376          *
 377          * @param string  $request request url
 378          * @param integer $uid     User id of the requester
 379          *
 380          * @return array JSON array
 381          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 382          */
 383         public static function fetch($request, $uid)
 384         {
 385                 $curlResult = self::fetchRaw($request, $uid);
 386
 387                 if (empty($curlResult)) {
 388                         return false;
 389                 }
 390
 391                 if (!$curlResult->isSuccess() || empty($curlResult->getBody())) {
 392                         return false;
 393                 }
 394
 395                 $content = json_decode($curlResult->getBody(), true);
 396                 if (empty($content) || !is_array($content)) {
 397                         return false;
 398                 }
 399
 400                 return $content;
 401         }
 402
 403         /**
 404          * Fetches raw data for a user
 405          *
 406          * @param string  $request request url
 407          * @param integer $uid     User id of the requester
 408          * @param boolean $binary  TRUE if asked to return binary results (file download) (default is "false")
 409          * @param array   $opts    (optional parameters) assoziative array with:
 410          *                         'accept_content' => supply Accept: header with 'accept_content' as the value
 411          *                         'timeout' => int Timeout in seconds, default system config value or 60 seconds
 412          *                         'nobody' => only return the header
 413          *                         'cookiejar' => path to cookie jar file
 414          *
 415          * @return \Friendica\Network\HTTPClient\Capability\ICanHandleHttpResponses CurlResult
 416          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 417          */
 418         public static function fetchRaw($request, $uid = 0, $opts = ['accept_content' => ['application/activity+json, application/ld+json; profile="https://www.w3.org/ns/activitystreams"']])
 419         {
 420                 $header = [];
 421
 422                 if (!empty($uid)) {
 423                         $owner = User::getOwnerDataById($uid);
 424                         if (!$owner) {
 425                                 return;
 426                         }
 427                 } else {
 428                         $owner = User::getSystemAccount();
 429                         if (!$owner) {
 430                                 return;
 431                         }
 432                 }
 433
 434                 if (!empty($owner['uprvkey'])) {
 435                         // Header data that is about to be signed.
 436                         $host = parse_url($request, PHP_URL_HOST);
 437                         $path = parse_url($request, PHP_URL_PATH);
 438                         $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 439
 440                         $header['Date'] = $date;
 441                         $header['Host'] = $host;
 442
 443                         $signed_data = "(request-target): get " . $path . "\ndate: ". $date . "\nhost: " . $host;
 444
 445                         $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 446
 447                         $header['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date host",signature="' . $signature . '"';
 448                 }
 449
 450                 $curl_opts                             = $opts;
 451                 $curl_opts[HttpClientOptions::HEADERS] = $header;
 452
 453                 if (!empty($opts['nobody'])) {
 454                         $curlResult = DI::httpClient()->head($request, $curl_opts);
 455                 } else {
 456                         $curlResult = DI::httpClient()->get($request, $curl_opts);
 457                 }
 458                 $return_code = $curlResult->getReturnCode();
 459
 460                 Logger::info('Fetched for user ' . $uid . ' from ' . $request . ' returned ' . $return_code);
 461
 462                 return $curlResult;
 463         }
 464
 465         /**
 466          * Gets a signer from a given HTTP request
 467          *
 468          * @param $content
 469          * @param $http_headers
 470          *
 471          * @return string Signer
 472          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 473          */
 474         public static function getSigner($content, $http_headers)
 475         {
 476                 if (empty($http_headers['HTTP_SIGNATURE'])) {
 477                         Logger::debug('No HTTP_SIGNATURE header');
 478                         return false;
 479                 }
 480
 481                 if (!empty($content)) {
 482                         $object = json_decode($content, true);
 483                         if (empty($object)) {
 484                                 Logger::info('No object');
 485                                 return false;
 486                         }
 487
 488                         $actor = JsonLD::fetchElement($object, 'actor', 'id');
 489                 } else {
 490                         $actor = '';
 491                 }
 492
 493                 $headers = [];
 494                 $headers['(request-target)'] = strtolower(DI::args()->getMethod()) . ' ' . parse_url($http_headers['REQUEST_URI'], PHP_URL_PATH);
 495
 496                 // First take every header
 497                 foreach ($http_headers as $k => $v) {
 498                         $field = str_replace('_', '-', strtolower($k));
 499                         $headers[$field] = $v;
 500                 }
 501
 502                 // Now add every http header
 503                 foreach ($http_headers as $k => $v) {
 504                         if (strpos($k, 'HTTP_') === 0) {
 505                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
 506                                 $headers[$field] = $v;
 507                         }
 508                 }
 509
 510                 $sig_block = self::parseSigHeader($http_headers['HTTP_SIGNATURE']);
 511
 512                 if (empty($sig_block) || empty($sig_block['headers']) || empty($sig_block['keyId'])) {
 513                         Logger::info('No headers or keyId');
 514                         return false;
 515                 }
 516
 517                 $signed_data = '';
 518                 foreach ($sig_block['headers'] as $h) {
 519                         if (array_key_exists($h, $headers)) {
 520                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
 521                         }
 522                 }
 523                 $signed_data = rtrim($signed_data, "\n");
 524
 525                 if (empty($signed_data)) {
 526                         Logger::info('Signed data is empty');
 527                         return false;
 528                 }
 529
 530                 $algorithm = null;
 531
 532                 // Wildcard value where signing algorithm should be derived from keyId
 533                 // @see https://tools.ietf.org/html/draft-ietf-httpbis-message-signatures-00#section-4.1
 534                 // Defaulting to SHA256 as it seems to be the prevalent implementation
 535                 // @see https://arewehs2019yet.vpzom.click
 536                 if ($sig_block['algorithm'] === 'hs2019') {
 537                         $algorithm = 'sha256';
 538                 }
 539
 540                 if ($sig_block['algorithm'] === 'rsa-sha256') {
 541                         $algorithm = 'sha256';
 542                 }
 543
 544                 if ($sig_block['algorithm'] === 'rsa-sha512') {
 545                         $algorithm = 'sha512';
 546                 }
 547
 548                 if (empty($algorithm)) {
 549                         Logger::info('No alagorithm');
 550                         return false;
 551                 }
 552
 553                 $key = self::fetchKey($sig_block['keyId'], $actor);
 554                 if (empty($key)) {
 555                         Logger::info('Empty key');
 556                         return false;
 557                 }
 558
 559                 if (!empty($key['url']) && !empty($key['type']) && ($key['type'] == 'Tombstone')) {
 560                         Logger::info('Actor is a tombstone', ['key' => $key]);
 561
 562                         if (!Contact::isLocal($key['url'])) {
 563                                 // We now delete everything that we possibly knew from this actor
 564                                 Contact::deleteContactByUrl($key['url']);
 565                         }
 566                         return null;
 567                 }
 568
 569                 if (empty($key['pubkey'])) {
 570                         Logger::info('Empty pubkey');
 571                         return false;
 572                 }
 573
 574                 if (!Crypto::rsaVerify($signed_data, $sig_block['signature'], $key['pubkey'], $algorithm)) {
 575                         Logger::info('Verification failed');
 576                         return false;
 577                 }
 578
 579                 $hasGoodSignedContent = false;
 580
 581                 // Check the digest when it is part of the signed data
 582                 if (!empty($content) && in_array('digest', $sig_block['headers'])) {
 583                         $digest = explode('=', $headers['digest'], 2);
 584                         if ($digest[0] === 'SHA-256') {
 585                                 $hashalg = 'sha256';
 586                         }
 587                         if ($digest[0] === 'SHA-512') {
 588                                 $hashalg = 'sha512';
 589                         }
 590
 591                         /// @todo add all hashes from the rfc
 592
 593                         if (!empty($hashalg) && base64_encode(hash($hashalg, $content, true)) != $digest[1]) {
 594                                 Logger::info('Digest does not match');
 595                                 return false;
 596                         }
 597
 598                         $hasGoodSignedContent = true;
 599                 }
 600
 601                 //  Check if the signed date field is in an acceptable range
 602                 if (in_array('date', $sig_block['headers'])) {
 603                         $diff = abs(strtotime($headers['date']) - time());
 604                         if ($diff > 300) {
 605                                 Logger::notice("Header date '" . $headers['date'] . "' is with " . $diff . " seconds out of the 300 second frame. The signature is invalid.");
 606                                 return false;
 607                         }
 608                         $hasGoodSignedContent = true;
 609                 }
 610
 611                 // Check the content-length when it is part of the signed data
 612                 if (in_array('content-length', $sig_block['headers'])) {
 613                         if (strlen($content) != $headers['content-length']) {
 614                                 Logger::info('Content length does not match');
 615                                 return false;
 616                         }
 617                 }
 618
 619                 // Ensure that the authentication had been done with some content
 620                 // Without this check someone could authenticate with fakeable data
 621                 if (!$hasGoodSignedContent) {
 622                         Logger::info('No good signed content');
 623                         return false;
 624                 }
 625
 626                 return $key['url'];
 627         }
 628
 629         /**
 630          * fetches a key for a given id and actor
 631          *
 632          * @param $id
 633          * @param $actor
 634          *
 635          * @return array with actor url and public key
 636          * @throws \Exception
 637          */
 638         private static function fetchKey($id, $actor)
 639         {
 640                 $url = (strpos($id, '#') ? substr($id, 0, strpos($id, '#')) : $id);
 641
 642                 $profile = APContact::getByURL($url);
 643                 if (!empty($profile)) {
 644                         Logger::info('Taking key from id', ['id' => $id]);
 645                         return ['url' => $url, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 646                 } elseif ($url != $actor) {
 647                         $profile = APContact::getByURL($actor);
 648                         if (!empty($profile)) {
 649                                 Logger::info('Taking key from actor', ['actor' => $actor]);
 650                                 return ['url' => $actor, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 651                         }
 652                 }
 653
 654                 Logger::notice('Key could not be fetched', ['url' => $url, 'actor' => $actor]);
 655                 return false;
 656         }
 657 }