Issue 8714: Make redirects more secure

mod/redir.php

@@ -31,6 +31,9 @@ use Friendica\Util\Network;
 use Friendica\Util\Strings;
 
 function redir_init(App $a) {
+	if (!Session::isAuthenticated()) {
+		throw new \Friendica\Network\HTTPException\ForbiddenException(DI::l10n()->t('Access denied.'));
+	}
 
 	$url = $_GET['url'] ?? '';
 	$quiet = !empty($_GET['quiet']) ? '&quiet=1' : '';
@@ -44,19 +47,21 @@ function redir_init(App $a) {
 	// Try magic auth before the legacy stuff
 	redir_magic($a, $cid, $url);
 
-	if (!empty($cid)) {
+	if (empty($cid)) {
+		throw new \Friendica\Network\HTTPException\NotFoundException(DI::l10n()->t('Contact not found.'));
+	}
+
 	$fields = ['id', 'uid', 'nurl', 'url', 'addr', 'name', 'network', 'poll', 'issued-id', 'dfrn-id', 'duplex', 'pending'];
 	$contact = DBA::selectFirst('contact', $fields, ['id' => $cid, 'uid' => [0, local_user()]]);
 	if (!DBA::isResult($contact)) {
-			notice(DI::l10n()->t('Contact not found.'));
+		throw new \Friendica\Network\HTTPException\NotFoundException(DI::l10n()->t('Contact not found.'));
-			DI::baseUrl()->redirect();
 	}
 
 	$contact_url = $contact['url'];
 
-		if (!Session::isAuthenticated() // Visitors (not logged in or not remotes) can't authenticate.
+	if (!empty($a->contact['id']) && $a->contact['id'] == $cid) {
-			|| (!empty($a->contact['id']) && $a->contact['id'] == $cid)) // Local user is already authenticated.
+		// Local user is already authenticated.
-		{
+		redir_check_url($contact_url, $url);
 		$a->redirect($url ?: $contact_url);
 	}
 
@@ -71,6 +76,7 @@ function redir_init(App $a) {
 
 		if (!empty($a->contact['id']) && $a->contact['id'] == $cid) {
 			// Local user is already authenticated.
+			redir_check_url($contact_url, $url);
 			$target_url = $url ?: $contact_url;
 			Logger::log($contact['name'] . " is already authenticated. Redirecting to " . $target_url, Logger::DEBUG);
 			$a->redirect($target_url);
@@ -87,6 +93,7 @@ function redir_init(App $a) {
 		// contact.
 		if (($host == $remotehost) && (Session::getRemoteContactID(Session::get('visitor_visiting')) == Session::get('visitor_id'))) {
 			// Remote user is already authenticated.
+			redir_check_url($contact_url, $url);
 			$target_url = $url ?: $contact_url;
 			Logger::log($contact['name'] . " is already authenticated. Redirecting to " . $target_url, Logger::DEBUG);
 			$a->redirect($target_url);
@@ -118,14 +125,17 @@ function redir_init(App $a) {
 
 		System::externalRedirect($contact['poll'] . '?dfrn_id=' . $dfrn_id
 			. '&dfrn_version=' . DFRN_PROTOCOL_VERSION . '&type=profile&sec=' . $sec . $dest . $quiet);
+
+		redir_check_url($contact_url, $url);
+		$url = $url ?: $contact_url;
 	}
 
-		$url = $url ?: $contact_url;
+	if (empty($url)) {
+		throw new \Friendica\Network\HTTPException\NotFoundException(DI::l10n()->t('Contact not found.'));
 	}
 
 	// If we don't have a connected contact, redirect with
 	// the 'zrl' parameter.
-	if (!empty($url)) {
 	$my_profile = Profile::getMyURL();
 
 	if (!empty($my_profile) && !Strings::compareLink($my_profile, $url)) {
@@ -138,10 +148,6 @@ function redir_init(App $a) {
 	$a->redirect($url);
 }
 
-	notice(DI::l10n()->t('Contact not found.'));
-	DI::baseUrl()->redirect();
-}
-
 function redir_magic($a, $cid, $url)
 {
 	$visitor = Profile::getMyURL();
@@ -152,15 +158,10 @@ function redir_magic($a, $cid, $url)
 	$contact = DBA::selectFirst('contact', ['url'], ['id' => $cid]);
 	if (!DBA::isResult($contact)) {
 		Logger::info('Contact not found', ['id' => $cid]);
-		// Shouldn't happen under normal conditions
+		throw new \Friendica\Network\HTTPException\NotFoundException(DI::l10n()->t('Contact not found.'));
-		notice(DI::l10n()->t('Contact not found.'));
-		if (!empty($url)) {
-			System::externalRedirect($url);
-		} else {
-			DI::baseUrl()->redirect();
-		}
 	} else {
 		$contact_url = $contact['url'];
+		redir_check_url($contact_url, $url);
 		$target_url = $url ?: $contact_url;
 	}
 
@@ -184,3 +185,20 @@ function redir_magic($a, $cid, $url)
 		Logger::info('No magic for contact', ['contact' => $contact_url]);
 	}
 }
+
+function redir_check_url(string $contact_url, string $url)
+{
+	if (empty($contact_url) || empty($url)) {
+		return;
+	}
+
+	$url_host = parse_url($url, PHP_URL_HOST);
+	$contact_url_host = parse_url($contact_url, PHP_URL_HOST);
+
+	if ($url_host == $contact_url_host) {
+		return;
+	}
+
+	Logger::error('URL check host mismatch', ['contact' => $contact_url, 'url' => $url]);
+	throw new \Friendica\Network\HTTPException\ForbiddenException(DI::l10n()->t('Access denied.'));
+}