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Differences Between: [Versions 310 and 401] [Versions 311 and 401] [Versions 39 and 401] [Versions 401 and 403]

   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  use auth_lti\local\ltiadvantage\entity\user_migration_claim;
  18  
  19  defined('MOODLE_INTERNAL') || die();
  20  
  21  require_once($CFG->libdir.'/authlib.php');
  22  require_once($CFG->libdir.'/accesslib.php');
  23  
  24  /**
  25   * LTI Authentication plugin.
  26   *
  27   * @package auth_lti
  28   * @copyright 2016 Mark Nelson <markn@moodle.com>
  29   * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  30   */
  31  class auth_plugin_lti extends \auth_plugin_base {
  32  
  33      /**
  34       * @var int constant representing the automatic account provisioning mode.
  35       * On first launch, for a previously unbound user, this mode dictates that a new Moodle account will be created automatically
  36       * for the user and bound to their platform credentials {iss, sub}.
  37       */
  38      public const PROVISIONING_MODE_AUTO_ONLY = 1;
  39  
  40      /**
  41       * @var int constant representing the prompt for new or existing provisioning mode.
  42       * On first launch, for a previously unbound user, the mode dictates that the launch user will be presented with an options
  43       * view, allowing them to select either 'link an existing account' or 'create a new account for me'.
  44       */
  45      public const PROVISIONING_MODE_PROMPT_NEW_EXISTING = 2;
  46  
  47      /**
  48       * @var int constant representing the prompt for existing only provisioning mode.
  49       * On first launch, for a previously unbound user, the mode dictates that the launch user will be presented with a view allowing
  50       * them to link an existing account only. This is useful for situations like deep linking, where an existing account is needed.
  51       */
  52      public const PROVISIONING_MODE_PROMPT_EXISTING_ONLY = 3;
  53  
  54      /**
  55       * Constructor.
  56       */
  57      public function __construct() {
  58          $this->authtype = 'lti';
  59      }
  60  
  61      /**
  62       * Users can not log in via the traditional login form.
  63       *
  64       * @param string $username The username
  65       * @param string $password The password
  66       * @return bool Authentication success or failure
  67       */
  68      public function user_login($username, $password) {
  69          return false;
  70      }
  71  
  72      /**
  73       * Authenticate the user based on the unique {iss, sub} tuple present in the OIDC JWT.
  74       *
  75       * This method ensures a Moodle user account has been found or is created, that the user is linked to the relevant
  76       * LTI Advantage credentials (iss, sub) and that the user account is logged in.
  77       *
  78       * Launch code can therefore rely on this method to get a session before doing things like calling require_login().
  79       *
  80       * This method supports two workflows:
  81       * 1. Automatic account provisioning - where the complete_login() call will ALWAYS create/find a user and return to
  82       * calling code directly. No user interaction is required.
  83       *
  84       * 2. Manual account provisioning - where the complete_login() call will redirect ONLY ONCE to a login page,
  85       * where the user can decide whether to use an automatically provisioned account, or bind an existing user account.
  86       * When the decision has been made, the relevant account is bound and the user is redirected back to $returnurl.
  87       * Once an account has been bound via this selection process, subsequent calls to complete_login() will return to
  88       * calling code directly. Any calling code must provide its $returnurl to support the return from the account
  89       * selection process and must also take care to cache any JWT data appropriately, since the return will not inlude
  90       * that information.
  91       *
  92       * Which workflow is chosen depends on the roles present in the JWT.
  93       * For teachers/admins, manual provisioning will take place. These user type are likely to have existing accounts.
  94       * For learners, automatic provisioning will take place.
  95       *
  96       * Migration of legacy users is supported, however, only for the Learner role (automatic provisioning). Admins and
  97       * teachers are likely to have existing accounts and we want them to be able to select and bind these, rather than
  98       * binding an automatically provisioned legacy account which doesn't represent their real user account.
  99       *
 100       * The JWT data must be verified elsewhere. The code here assumes its integrity/authenticity.
 101       *
 102       * @param array $launchdata the JWT data provided in the link launch.
 103       * @param moodle_url $returnurl the local URL to return to if authentication workflows are required.
 104       * @param int $provisioningmode the desired account provisioning mode, which controls the auth flow for unbound users.
 105       * @param array $legacyconsumersecrets an array of secrets used by the legacy consumer if a migration claim exists.
 106       * @throws coding_exception if the specified provisioning mode is invalid.
 107       */
 108      public function complete_login(array $launchdata, moodle_url $returnurl, int $provisioningmode,
 109              array $legacyconsumersecrets = []): void {
 110  
 111          // The platform user is already linked with a user account.
 112          if ($this->get_user_binding($launchdata['iss'], $launchdata['sub'])) {
 113              // Always sync the PII, regardless of whether we're already authenticated as this user or not.
 114              $user = $this->find_or_create_user_from_launch($launchdata, true);
 115  
 116              if (isloggedin()) {
 117                  // If a different user is currently logged in, authenticate the linked user instead.
 118                  global $USER;
 119                  if ((int) $USER->id !== $user->id) {
 120                      complete_user_login($user);
 121                  }
 122                  // If the linked user is already logged in, skip the call to complete_user_login() because this affects deep linking
 123                  // workflows on sites publishing and consuming resources on the same site, due to the regenerated sesskey.
 124                  return;
 125              } else {
 126                  complete_user_login($user);
 127                  return;
 128              }
 129          }
 130  
 131          // The platform user is not bound to a user account, check provisioning mode now.
 132          if (!$this->is_valid_provisioning_mode($provisioningmode)) {
 133              throw new coding_exception('Invalid account provisioning mode provided to complete_login().');
 134          }
 135  
 136          switch ($provisioningmode) {
 137              case self::PROVISIONING_MODE_AUTO_ONLY:
 138                  // Automatic provisioning - this will create/migrate a user account and log the user in.
 139                  complete_user_login($this->find_or_create_user_from_launch($launchdata, true, $legacyconsumersecrets));
 140                  break;
 141              case self::PROVISIONING_MODE_PROMPT_NEW_EXISTING:
 142              case self::PROVISIONING_MODE_PROMPT_EXISTING_ONLY:
 143              default:
 144                  // Allow linking an existing account or creation of a new account via an intermediate account options page.
 145                  // Cache the relevant data and take the user to the account options page.
 146                  // Note: This mode also depends on the global auth config 'authpreventaccountcreation'. If set, only existing
 147                  // accounts can be bound in this provisioning mode.
 148                  global $SESSION;
 149                  $SESSION->auth_lti = (object)[
 150                      'launchdata' => $launchdata,
 151                      'returnurl' => $returnurl,
 152                      'provisioningmode' => $provisioningmode
 153                  ];
 154                  redirect(new moodle_url('/auth/lti/login.php', [
 155                      'sesskey' => sesskey(),
 156                  ]));
 157                  break;
 158          }
 159      }
 160  
 161      /**
 162       * Get a Moodle user account for the LTI user based on the user details returned by a NRPS 2 membership call.
 163       *
 164       * This method expects a single member structure, in array format, as defined here:
 165       * See: https://www.imsglobal.org/spec/lti-nrps/v2p0#membership-container-media-type.
 166       *
 167       * This method supports migration of user accounts used in legacy launches, provided the legacy consumerkey corresponding to
 168       * to the legacy consumer is provided. Calling code will have verified the migration claim during initial launches and should
 169       * have the consumer key mapped to the deployment, ready to pass in.
 170       *
 171       * @param array $member the member data, in array format.
 172       * @param string $iss the issuer to which the member relates.
 173       * @param string $legacyconsumerkey optional consumer key mapped to the deployment to facilitate user migration.
 174       * @return stdClass a Moodle user record.
 175       */
 176      public function find_or_create_user_from_membership(array $member, string $iss,
 177              string $legacyconsumerkey = ''): stdClass {
 178  
 179          // Picture is not synced with membership-based auths because sync tasks may wish to perform slow operations like this a
 180          // different way.
 181          unset($member['picture']);
 182  
 183          if ($binduser = $this->get_user_binding($iss, $member['user_id'])) {
 184              $user = \core_user::get_user((int) $binduser);
 185              $this->update_user_account($user, $member, $iss);
 186              return \core_user::get_user($user->id);
 187          } else {
 188              if (!empty($legacyconsumerkey)) {
 189                  // Consumer key is required to attempt user migration because legacy users were identified by a
 190                  // username consisting of the consumer key and user id.
 191                  // See the legacy \enrol_lti\helper::create_username() for details.
 192                  $legacyuserid = $member['lti11_legacy_user_id'] ?? $member['user_id'];
 193                  $username = 'enrol_lti' .
 194                      sha1($legacyconsumerkey . '::' . $legacyconsumerkey . ':' . $legacyuserid);
 195                  if ($user = \core_user::get_user_by_username($username)) {
 196                      $this->create_user_binding($iss, $member['user_id'], $user->id);
 197                      $this->update_user_account($user, $member, $iss);
 198                      return \core_user::get_user($user->id);
 199                  }
 200              }
 201              $user = $this->create_new_account($member, $iss);
 202              return \core_user::get_user($user->id);
 203          }
 204      }
 205  
 206      /**
 207       * Get a Moodle user account for the LTI user corresponding to the user defined in a link launch.
 208       *
 209       * This method supports migration of user accounts used in legacy launches, provided the legacy consumer secrets corresponding
 210       * to the legacy consumer are provided. If calling code wishes migration to be role-specific, it should check roles accordingly
 211       * itself and pass relevant data in - as auth_plugin_lti::complete_login() does.
 212       *
 213       * @param array $launchdata all data in the decoded JWT including iss and sub.
 214       * @param bool $syncpicture whether to sync the user's picture with the picture sent in the launch.
 215       * @param array $legacyconsumersecrets all secrets found for the legacy consumer, facilitating user migration.
 216       * @return stdClass the Moodle user who is mapped to the platform user identified in the JWT data.
 217       */
 218      public function find_or_create_user_from_launch(array $launchdata, bool $syncpicture = false,
 219              array $legacyconsumersecrets = []): stdClass {
 220  
 221          if (!$syncpicture) {
 222              unset($launchdata['picture']);
 223          }
 224  
 225          if ($binduser = $this->get_user_binding($launchdata['iss'], $launchdata['sub'])) {
 226              $user = \core_user::get_user((int) $binduser);
 227              $this->update_user_account($user, $launchdata, $launchdata['iss']);
 228              return \core_user::get_user($user->id);
 229          } else {
 230              // Is the intent to migrate a user account used in legacy launches?
 231              if (!empty($legacyconsumersecrets)) {
 232                  try {
 233                      // Validate the migration claim and try to find a legacy user.
 234                      $usermigrationclaim = new user_migration_claim($launchdata, $legacyconsumersecrets);
 235                      $username = 'enrol_lti' .
 236                          sha1($usermigrationclaim->get_consumer_key() . '::' .
 237                          $usermigrationclaim->get_consumer_key() .':' .$usermigrationclaim->get_user_id());
 238                      if ($user = \core_user::get_user_by_username($username)) {
 239                          $this->create_user_binding($launchdata['iss'], $launchdata['sub'], $user->id);
 240                          $this->update_user_account($user, $launchdata, $launchdata['iss']);
 241                          return \core_user::get_user($user->id);
 242                      }
 243                  } catch (Exception $e) {
 244                      // There was an issue validating the user migration claim. We don't want to fail auth entirely though.
 245                      // Rather, we want to fall back to new account creation and log the attempt.
 246                      debugging("There was a problem migrating the LTI user '{$launchdata['sub']}' on the platform " .
 247                          "'{$launchdata['iss']}'. The migration claim could not be validated. A new account will be created.");
 248                  }
 249              }
 250              $user = $this->create_new_account($launchdata, $launchdata['iss']);
 251              $this->update_user_account($user, $launchdata, $launchdata['iss']);
 252              return \core_user::get_user($user->id);
 253          }
 254      }
 255  
 256      /**
 257       * Create a binding between the LTI user, as identified by {iss, sub} tuple and the user id.
 258       *
 259       * @param string $iss the issuer URL identifying the platform to which to user belongs.
 260       * @param string $sub the sub string identifying the user on the platform.
 261       * @param int $userid the id of the Moodle user account to bind.
 262       */
 263      public function create_user_binding(string $iss, string $sub, int $userid): void {
 264          global $DB;
 265  
 266          $timenow = time();
 267          $issuer256 = hash('sha256', $iss);
 268          $sub256 = hash('sha256', $sub);
 269          if ($DB->record_exists('auth_lti_linked_login', ['issuer256' => $issuer256, 'sub256' => $sub256])) {
 270              return;
 271          }
 272          $rec = [
 273              'userid' => $userid,
 274              'issuer' => $iss,
 275              'issuer256' => $issuer256,
 276              'sub' => $sub,
 277              'sub256' => $sub256,
 278              'timecreated' => $timenow,
 279              'timemodified' => $timenow
 280          ];
 281          $DB->insert_record('auth_lti_linked_login', $rec);
 282      }
 283  
 284      /**
 285       * Gets the id of the linked Moodle user account for an LTI user, or null if not found.
 286       *
 287       * @param string $issuer the issuer to which the user belongs.
 288       * @param string $sub the sub string identifying the user on the issuer.
 289       * @return int|null the id of the corresponding Moodle user record, or null if not found.
 290       */
 291      public function get_user_binding(string $issuer, string $sub): ?int {
 292          global $DB;
 293          $issuer256 = hash('sha256', $issuer);
 294          $sub256 = hash('sha256', $sub);
 295          try {
 296              $binduser = $DB->get_field('auth_lti_linked_login', 'userid',
 297                  ['issuer256' => $issuer256, 'sub256' => $sub256], MUST_EXIST);
 298          } catch (\dml_exception $e) {
 299              $binduser = null;
 300          }
 301          return $binduser;
 302      }
 303  
 304      /**
 305       * Check whether a provisioning mode is valid or not.
 306       *
 307       * @param int $mode the mode
 308       * @return bool true if valid for use, false otherwise.
 309       */
 310      protected function is_valid_provisioning_mode(int $mode): bool {
 311          $validmodes = [
 312              self::PROVISIONING_MODE_AUTO_ONLY,
 313              self::PROVISIONING_MODE_PROMPT_NEW_EXISTING,
 314              self::PROVISIONING_MODE_PROMPT_EXISTING_ONLY
 315          ];
 316          return in_array($mode, $validmodes);
 317      }
 318  
 319      /**
 320       * Create a new user account based on the user data either in the launch JWT or from a membership call.
 321       *
 322       * @param array $userdata the user data coming from either a launch or membership service call.
 323       * @param string $iss the issuer to which the user belongs.
 324       * @return stdClass a complete Moodle user record.
 325       */
 326      protected function create_new_account(array $userdata, string $iss): stdClass {
 327  
 328          global $CFG;
 329          require_once($CFG->dirroot.'/user/lib.php');
 330  
 331          // Launches and membership calls handle the user id differently.
 332          // Launch uses 'sub', whereas member uses 'user_id'.
 333          $userid = !empty($userdata['sub']) ? $userdata['sub'] : $userdata['user_id'];
 334  
 335          $user = new stdClass();
 336          $user->username = 'enrol_lti_13_' . sha1($iss . '_' . $userid);
 337          // If the email was stripped/not set then fill it with a default one.
 338          // This stops the user from being redirected to edit their profile page.
 339          $email = !empty($userdata['email']) ? $userdata['email'] :
 340              'enrol_lti_13_' . sha1($iss . '_' . $userid) . "@example.com";
 341          $email = \core_user::clean_field($email, 'email');
 342          $user->email = $email;
 343          $user->auth = 'lti';
 344          $user->mnethostid = $CFG->mnet_localhost_id;
 345          $user->firstname = $userdata['given_name'] ?? $userid;
 346          $user->lastname = $userdata['family_name'] ?? $iss;
 347          $user->password = '';
 348          $user->confirmed = 1;
 349          $user->id = user_create_user($user, false);
 350  
 351          // Link this user with the LTI credentials for future use.
 352          $this->create_user_binding($iss, $userid, $user->id);
 353  
 354          return (object) get_complete_user_data('id', $user->id);
 355      }
 356  
 357      /**
 358       * Update the personal fields of the user account, based on data present in either a launch of member sync call.
 359       *
 360       * @param stdClass $user the Moodle user account to update.
 361       * @param array $userdata the user data coming from either a launch or membership service call.
 362       * @param string $iss the issuer to which the user belongs.
 363       */
 364      protected function update_user_account(stdClass $user, array $userdata, string $iss): void {
 365          global $CFG;
 366          require_once($CFG->dirroot.'/user/lib.php');
 367          if ($user->auth !== 'lti') {
 368              return;
 369          }
 370  
 371          // Launches and membership calls handle the user id differently.
 372          // Launch uses 'sub', whereas member uses 'user_id'.
 373          $platformuserid = !empty($userdata['sub']) ? $userdata['sub'] : $userdata['user_id'];
 374          $email = !empty($userdata['email']) ? $userdata['email'] :
 375              'enrol_lti_13_' . sha1($iss . '_' . $platformuserid) . "@example.com";
 376          $email = \core_user::clean_field($email, 'email');
 377          $update = [
 378              'id' => $user->id,
 379              'firstname' => $userdata['given_name'] ?? $platformuserid,
 380              'lastname' => $userdata['family_name'] ?? $iss,
 381              'email' => $email
 382          ];
 383          $userfieldstocompare = array_intersect_key((array) $user, $update);
 384  
 385          if (!empty(array_diff($update, $userfieldstocompare))) {
 386              user_update_user($update); // Only update if there's a change.
 387          }
 388  
 389          if (!empty($userdata['picture'])) {
 390              try {
 391                  $this->update_user_picture($user->id, $userdata['picture']);
 392              } catch (Exception $e) {
 393                  debugging("Error syncing the profile picture for user '$user->id' during LTI authentication.");
 394              }
 395          }
 396      }
 397  
 398      /**
 399       * Update the user's picture with the image stored at $url.
 400       *
 401       * @param int $userid the id of the user to update.
 402       * @param string $url the string URL where the new image can be found.
 403       * @throws moodle_exception if there were any problems updating the picture.
 404       */
 405      protected function update_user_picture(int $userid, string $url): void {
 406          global $CFG, $DB;
 407  
 408          require_once($CFG->libdir . '/filelib.php');
 409          require_once($CFG->libdir . '/gdlib.php');
 410  
 411          $fs = get_file_storage();
 412  
 413          $context = \context_user::instance($userid, MUST_EXIST);
 414          $fs->delete_area_files($context->id, 'user', 'newicon');
 415  
 416          $filerecord = array(
 417              'contextid' => $context->id,
 418              'component' => 'user',
 419              'filearea' => 'newicon',
 420              'itemid' => 0,
 421              'filepath' => '/'
 422          );
 423  
 424          $urlparams = array(
 425              'calctimeout' => false,
 426              'timeout' => 5,
 427              'skipcertverify' => true,
 428              'connecttimeout' => 5
 429          );
 430  
 431          try {
 432              $fs->create_file_from_url($filerecord, $url, $urlparams);
 433          } catch (\file_exception $e) {
 434              throw new moodle_exception(get_string($e->errorcode, $e->module, $e->a));
 435          }
 436  
 437          $iconfile = $fs->get_area_files($context->id, 'user', 'newicon', false, 'itemid', false);
 438  
 439          // There should only be one.
 440          $iconfile = reset($iconfile);
 441  
 442          // Something went wrong while creating temp file - remove the uploaded file.
 443          if (!$iconfile = $iconfile->copy_content_to_temp()) {
 444              $fs->delete_area_files($context->id, 'user', 'newicon');
 445              throw new moodle_exception('There was a problem copying the profile picture to temp.');
 446          }
 447  
 448          // Copy file to temporary location and the send it for processing icon.
 449          $newpicture = (int) process_new_icon($context, 'user', 'icon', 0, $iconfile);
 450          // Delete temporary file.
 451          @unlink($iconfile);
 452          // Remove uploaded file.
 453          $fs->delete_area_files($context->id, 'user', 'newicon');
 454          // Set the user's picture.
 455          $DB->set_field('user', 'picture', $newpicture, array('id' => $userid));
 456      }
 457  }