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<?php |
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namespace LeKoala\DeferBackend; |
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use SilverStripe\Control\Director; |
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use SilverStripe\Control\HTTPResponse; |
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use SilverStripe\Core\Config\Configurable; |
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use SilverStripe\View\TemplateGlobalProvider; |
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/** |
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* A dead simple csp provider |
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* |
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* @link https://csp.withgoogle.com/docs/strict-csp.html |
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* @link https://content-security-policy.com/strict-dynamic/ |
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*/ |
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class CspProvider implements TemplateGlobalProvider |
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{ |
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use Configurable; |
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/** |
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* @config |
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* @var string |
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*/ |
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private static $default_referrer_policy = "no-referrer-when-downgrade"; |
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/** |
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* @config |
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* @var bool |
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*/ |
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private static $enable_hsts = true; |
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/** |
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* @config |
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* @var string |
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*/ |
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private static $hsts_header = 'max-age=300; includeSubDomains; preload; always;'; |
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/** |
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* @config |
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* @var bool |
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*/ |
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private static $enable_csp = false; |
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/** |
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* @config |
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* @var string |
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*/ |
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private static $frame_ancestors = "'self'"; |
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/** |
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* @config |
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* @var string |
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*/ |
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private static $frame_options = "SAMEORIGIN"; |
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/** |
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* @config |
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* @var string |
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*/ |
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private static $csp_report_uri = null; |
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/** |
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* @config |
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* @var bool |
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*/ |
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private static $csp_report_only = true; |
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/** |
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* @var string |
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*/ |
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protected static $csp_nonce = null; |
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/** |
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* Allows calling getCspNonce in the template for script inclusion |
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* |
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* @return array<string,string> |
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*/ |
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public static function get_template_global_variables() |
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{ |
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return [ |
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'getCspNonce' => 'getCspNonce' |
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]; |
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} |
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/** |
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* @link https://content-security-policy.com/nonce/ |
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* @return string |
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*/ |
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public static function getCspNonce() |
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{ |
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if (!self::$csp_nonce) { |
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self::$csp_nonce = str_replace(["/", "+"], "", base64_encode(random_bytes(18))); |
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} |
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return self::$csp_nonce; |
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} |
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/** |
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* Allow setting nonce from an external source |
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* @param string $nonce |
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* @return void |
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*/ |
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public static function setCspNonce($nonce) |
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{ |
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self::$csp_nonce = $nonce; |
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} |
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/** |
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* @param HTTPResponse $response |
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* @return HTTPResponse |
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*/ |
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public static function addSecurityHeaders(HTTPResponse $response) |
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{ |
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$config = self::config(); |
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// @link https://web.dev/referrer-best-practices/ |
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if ($config->default_referrer_policy) { |
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$response->addHeader('Referrer-Policy', $config->default_referrer_policy); |
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} |
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// enable HTTP Strict Transport Security |
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if ($config->enable_hsts && $config->hsts_header && Director::is_https()) { |
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$response->addHeader('Strict-Transport-Security', $config->hsts_header); |
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} |
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// |
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if ($config->frame_options) { |
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if (!$response->getHeader('X-Frame-Options')) { |
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$response->addHeader('X-Frame-Options', $config->frame_options); |
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} |
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} |
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return $response; |
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} |
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/** |
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* Add CSP to the response using a flexible strict dynamic way |
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* |
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* @param HTTPResponse $response |
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* @return void |
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*/ |
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public static function addCspHeaders(HTTPResponse $response) |
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{ |
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// Only supported in https |
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if (!Director::is_https()) { |
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return; |
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} |
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$config = self::config(); |
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// Only add if enabled in config |
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if (!$config->enable_csp) { |
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return; |
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} |
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$csp = "default-src 'self' data:"; |
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$csp .= ';'; |
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$csp .= "script-src 'nonce-" . self::getCspNonce() . "' 'strict-dynamic' 'unsafe-inline' 'unsafe-eval' https: http:;"; |
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$csp .= "style-src * 'unsafe-inline';"; |
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$csp .= "object-src 'self';"; |
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$csp .= "img-src * data:;"; |
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$csp .= "font-src * data:;"; |
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// @link https://cheatsheetseries.owasp.org/cheatsheets/Clickjacking_Defense_Cheat_Sheet.html#content-security-policy-frame-ancestors-examples |
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if ($config->frame_ancestors) { |
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$csp .= "frame-ancestors " . $config->frame_ancestors . ";"; |
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} |
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$report = $config->csp_report_uri; |
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$reportOnly = $config->csp_report_only; |
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if ($report) { |
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$csp .= "report-uri " . $report; |
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} |
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$headerName = 'Content-Security-Policy'; |
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if ($report && $reportOnly) { |
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$headerName = 'Content-Security-Policy-Report-Only'; |
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} |
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$response->addHeader($headerName, $csp); |
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} |
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} |
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lekoala /
silverstripe-defer-backend
