257 lines
8.1 KiB
PHP
257 lines
8.1 KiB
PHP
<?php
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/**
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* @package Grav\Common
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*
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* @copyright Copyright (c) 2015 - 2021 Trilby Media, LLC. All rights reserved.
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* @license MIT License; see LICENSE file for details.
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*/
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namespace Grav\Common;
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use enshrined\svgSanitize\Sanitizer;
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use Exception;
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use Grav\Common\Config\Config;
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use Grav\Common\Filesystem\Folder;
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use Grav\Common\Page\Pages;
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use function chr;
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use function count;
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use function is_array;
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use function is_string;
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/**
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* Class Security
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* @package Grav\Common
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*/
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class Security
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{
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/**
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* Sanitize SVG string for XSS code
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*
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* @param string $svg
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* @return string
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*/
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public static function sanitizeSvgString(string $svg): string
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{
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if (Grav::instance()['config']->get('security.sanitize_svg')) {
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$sanitizer = new Sanitizer();
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$sanitized = $sanitizer->sanitize($svg);
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if (is_string($sanitized)) {
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$svg = $sanitized;
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}
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}
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return $svg;
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}
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/**
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* Sanitize SVG for XSS code
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*
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* @param string $file
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* @return void
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*/
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public static function sanitizeSVG(string $file): void
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{
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if (file_exists($file) && Grav::instance()['config']->get('security.sanitize_svg')) {
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$sanitizer = new Sanitizer();
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$original_svg = file_get_contents($file);
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$clean_svg = $sanitizer->sanitize($original_svg);
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// Quarantine bad SVG files and throw exception
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if ($clean_svg !== false ) {
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file_put_contents($file, $clean_svg);
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} else {
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$quarantine_file = basename($file);
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$quarantine_dir = 'log://quarantine';
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Folder::mkdir($quarantine_dir);
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file_put_contents("$quarantine_dir/$quarantine_file", $original_svg);
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unlink($file);
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throw new Exception('SVG could not be sanitized, it has been moved to the logs/quarantine folder');
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}
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}
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}
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/**
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* Detect XSS code in Grav pages
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*
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* @param Pages $pages
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* @param bool $route
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* @param callable|null $status
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* @return array
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*/
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public static function detectXssFromPages(Pages $pages, $route = true, callable $status = null)
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{
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$routes = $pages->routes();
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// Remove duplicate for homepage
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unset($routes['/']);
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$list = [];
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// This needs Symfony 4.1 to work
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$status && $status([
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'type' => 'count',
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'steps' => count($routes),
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]);
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foreach ($routes as $path) {
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$status && $status([
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'type' => 'progress',
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]);
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try {
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$page = $pages->get($path);
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// call the content to load/cache it
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$header = (array) $page->header();
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$content = $page->value('content');
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$data = ['header' => $header, 'content' => $content];
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$results = Security::detectXssFromArray($data);
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if (!empty($results)) {
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if ($route) {
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$list[$page->route()] = $results;
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} else {
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$list[$page->filePathClean()] = $results;
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}
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}
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} catch (Exception $e) {
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continue;
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}
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}
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return $list;
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}
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/**
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* Detect XSS in an array or strings such as $_POST or $_GET
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*
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* @param array $array Array such as $_POST or $_GET
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* @param array|null $options Extra options to be passed.
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* @param string $prefix Prefix for returned values.
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* @return array Returns flatten list of potentially dangerous input values, such as 'data.content'.
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*/
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public static function detectXssFromArray(array $array, string $prefix = '', array $options = null)
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{
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if (null === $options) {
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$options = static::getXssDefaults();
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}
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$list = [];
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foreach ($array as $key => $value) {
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if (is_array($value)) {
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$list[] = static::detectXssFromArray($value, $prefix . $key . '.', $options);
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}
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if ($result = static::detectXss($value, $options)) {
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$list[] = [$prefix . $key => $result];
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}
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}
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if (!empty($list)) {
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return array_merge(...$list);
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}
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return $list;
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}
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/**
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* Determine if string potentially has a XSS attack. This simple function does not catch all XSS and it is likely to
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*
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* return false positives because of it tags all potentially dangerous HTML tags and attributes without looking into
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* their content.
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*
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* @param string|null $string The string to run XSS detection logic on
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* @param array|null $options
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* @return string|null Type of XSS vector if the given `$string` may contain XSS, false otherwise.
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*
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* Copies the code from: https://github.com/symphonycms/xssfilter/blob/master/extension.driver.php#L138
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*/
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public static function detectXss($string, array $options = null): ?string
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{
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// Skip any null or non string values
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if (null === $string || !is_string($string) || empty($string)) {
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return null;
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}
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if (null === $options) {
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$options = static::getXssDefaults();
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}
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$enabled_rules = (array)($options['enabled_rules'] ?? null);
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$dangerous_tags = (array)($options['dangerous_tags'] ?? null);
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if (!$dangerous_tags) {
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$enabled_rules['dangerous_tags'] = false;
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}
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$invalid_protocols = (array)($options['invalid_protocols'] ?? null);
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if (!$invalid_protocols) {
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$enabled_rules['invalid_protocols'] = false;
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}
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$enabled_rules = array_filter($enabled_rules, static function ($val) { return !empty($val); });
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if (!$enabled_rules) {
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return null;
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}
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// Keep a copy of the original string before cleaning up
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$orig = $string;
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// URL decode
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$string = urldecode($string);
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// Convert Hexadecimals
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$string = (string)preg_replace_callback('!(&#|\\\)[xX]([0-9a-fA-F]+);?!u', function ($m) {
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return chr(hexdec($m[2]));
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}, $string);
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// Clean up entities
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$string = preg_replace('!(�+[0-9]+)!u', '$1;', $string);
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// Decode entities
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$string = html_entity_decode($string, ENT_NOQUOTES, 'UTF-8');
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// Strip whitespace characters
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$string = preg_replace('!\s!u', '', $string);
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// Set the patterns we'll test against
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$patterns = [
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// Match any attribute starting with "on" or xmlns
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'on_events' => '#(<[^>]+[[a-z\x00-\x20\"\'\/])([\s\/]on|\sxmlns)[a-z].*=>?#iUu',
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// Match javascript:, livescript:, vbscript:, mocha:, feed: and data: protocols
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'invalid_protocols' => '#(' . implode('|', array_map('preg_quote', $invalid_protocols, ['#'])) . '):\S.*?#iUu',
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// Match -moz-bindings
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'moz_binding' => '#-moz-binding[a-z\x00-\x20]*:#u',
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// Match style attributes
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'html_inline_styles' => '#(<[^>]+[a-z\x00-\x20\"\'\/])(style=[^>]*(url\:|x\:expression).*)>?#iUu',
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// Match potentially dangerous tags
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'dangerous_tags' => '#</*(' . implode('|', array_map('preg_quote', $dangerous_tags, ['#'])) . ')[^>]*>?#ui'
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];
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// Iterate over rules and return label if fail
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foreach ($patterns as $name => $regex) {
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if (!empty($enabled_rules[$name])) {
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if (preg_match($regex, $string) || preg_match($regex, $orig)) {
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return $name;
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}
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}
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}
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return false;
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}
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public static function getXssDefaults(): array
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{
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/** @var Config $config */
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$config = Grav::instance()['config'];
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return [
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'enabled_rules' => $config->get('security.xss_enabled'),
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'dangerous_tags' => array_map('trim', $config->get('security.xss_dangerous_tags')),
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'invalid_protocols' => array_map('trim', $config->get('security.xss_invalid_protocols')),
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];
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}
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}
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