%PDF-
%PDF-
Mini Shell
Mini Shell
<?php
/**
* Handle sending Content-Security-Policy headers
*
* @see https://www.w3.org/TR/CSP2/
*
* Copyright © 2015–2018 Brian Wolff
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @since 1.32
* @file
*/
class ContentSecurityPolicy {
const REPORT_ONLY_MODE = 1;
const FULL_MODE = 2;
/** @var string The nonce to use for inline scripts (from OutputPage) */
private $nonce;
/** @var Config The site configuration object */
private $mwConfig;
/** @var WebResponse */
private $response;
/**
* @param string $nonce
* @param WebResponse $response
* @param Config $mwConfig
*/
public function __construct( $nonce, WebResponse $response, Config $mwConfig ) {
$this->nonce = $nonce;
$this->response = $response;
$this->mwConfig = $mwConfig;
}
/**
* Send a single CSP header based on a given policy config.
*
* @note Most callers will probably want ContentSecurityPolicy::sendHeaders() instead.
* @param array $csp ContentSecurityPolicy configuration
* @param int $reportOnly self::*_MODE constant
*/
public function sendCSPHeader( $csp, $reportOnly ) {
$policy = $this->makeCSPDirectives( $csp, $reportOnly );
$headerName = $this->getHeaderName( $reportOnly );
if ( $policy ) {
$this->response->header(
"$headerName: $policy"
);
}
}
/**
* Send CSP headers based on wiki config
*
* Main method that callers are expected to use
* @param IContextSource $context A context object, the associated OutputPage
* object must be the one that the page in question was generated with.
*/
public static function sendHeaders( IContextSource $context ) {
$out = $context->getOutput();
$csp = new ContentSecurityPolicy(
$out->getCSPNonce(),
$context->getRequest()->response(),
$context->getConfig()
);
$cspConfig = $context->getConfig()->get( 'CSPHeader' );
$cspConfigReportOnly = $context->getConfig()->get( 'CSPReportOnlyHeader' );
$csp->sendCSPHeader( $cspConfig, self::FULL_MODE );
$csp->sendCSPHeader( $cspConfigReportOnly, self::REPORT_ONLY_MODE );
// This used to insert a <meta> tag here, per advice at
// https://blogs.dropbox.com/tech/2015/09/unsafe-inline-and-nonce-deployment/
// The goal was to prevent nonce from working after the page hit onready,
// This would help in old browsers that didn't support nonces, and
// also assist for varnish-cached pages which repeat nonces.
// However, this is incompatible with how resource loader storage works
// via mw.domEval() so it was removed.
}
/**
* Get the name of the HTTP header to use.
*
* @param int $reportOnly Either self::REPORT_ONLY_MODE or self::FULL_MODE
* @return string Name of http header
*/
private function getHeaderName( $reportOnly ) {
if ( $reportOnly === self::REPORT_ONLY_MODE ) {
return 'Content-Security-Policy-Report-Only';
} elseif ( $reportOnly === self::FULL_MODE ) {
return 'Content-Security-Policy';
}
throw new UnexpectedValueException( $reportOnly );
}
/**
* Determine what CSP policies to set for this page
*
* @param array|bool $config Policy configuration (Either $wgCSPHeader or $wgCSPReportOnlyHeader)
* @param int $mode self::REPORT_ONLY_MODE, self::FULL_MODE
* @return string Policy directives, or empty string for no policy.
*/
private function makeCSPDirectives( $policyConfig, $mode ) {
if ( $policyConfig === false ) {
// CSP is disabled
return '';
}
if ( $policyConfig === true ) {
$policyConfig = [];
}
$mwConfig = $this->mwConfig;
$additionalSelfUrls = $this->getAdditionalSelfUrls();
$additionalSelfUrlsScript = $this->getAdditionalSelfUrlsScript();
// If no default-src is sent at all, it
// seems browsers (or at least some), interpret
// that as allow anything, but the spec seems
// to imply that data: and blob: should be
// blocked.
$defaultSrc = [ '*', 'data:', 'blob:' ];
$cssSrc = false;
$imgSrc = false;
$scriptSrc = [ "'unsafe-eval'", "'self'" ];
if ( !isset( $policyConfig['useNonces'] ) || $policyConfig['useNonces'] ) {
$scriptSrc[] = "'nonce-" . $this->nonce . "'";
}
$scriptSrc = array_merge( $scriptSrc, $additionalSelfUrlsScript );
if ( isset( $policyConfig['script-src'] )
&& is_array( $policyConfig['script-src'] )
) {
foreach ( $policyConfig['script-src'] as $src ) {
$scriptSrc[] = $this->escapeUrlForCSP( $src );
}
}
// Note: default on if unspecified.
if ( ( !isset( $policyConfig['unsafeFallback'] )
|| $policyConfig['unsafeFallback'] )
) {
// unsafe-inline should be ignored on browsers
// that support 'nonce-foo' sources.
// Some older versions of firefox don't follow this
// rule, but new browsers do. (Should be for at least
// firefox 40+).
$scriptSrc[] = "'unsafe-inline'";
}
// If default source option set to true or
// an array of urls, set a restrictive default-src.
// If set to false, we send a lenient default-src,
// see the code above where $defaultSrc is set initially.
if ( isset( $policyConfig['default-src'] )
&& $policyConfig['default-src'] !== false
) {
$defaultSrc = array_merge(
[ "'self'", 'data:', 'blob:' ],
$additionalSelfUrls
);
if ( is_array( $policyConfig['default-src'] ) ) {
foreach ( $policyConfig['default-src'] as $src ) {
$defaultSrc[] = $this->escapeUrlForCSP( $src );
}
}
}
if ( !isset( $policyConfig['includeCORS'] ) || $policyConfig['includeCORS'] ) {
$CORSUrls = $this->getCORSSources();
if ( !in_array( '*', $defaultSrc ) ) {
$defaultSrc = array_merge( $defaultSrc, $CORSUrls );
}
// Unlikely to have * in scriptSrc, but doesn't
// hurt to check.
if ( !in_array( '*', $scriptSrc ) ) {
$scriptSrc = array_merge( $scriptSrc, $CORSUrls );
}
}
Hooks::run( 'ContentSecurityPolicyDefaultSource', [ &$defaultSrc, $policyConfig, $mode ] );
Hooks::run( 'ContentSecurityPolicyScriptSource', [ &$scriptSrc, $policyConfig, $mode ] );
// Check if array just in case the hook made it false
if ( is_array( $defaultSrc ) ) {
$cssSrc = array_merge( $defaultSrc, [ "'unsafe-inline'" ] );
}
if ( isset( $policyConfig['report-uri'] ) && $policyConfig['report-uri'] !== true ) {
if ( $policyConfig['report-uri'] === false ) {
$reportUri = false;
} else {
$reportUri = $this->escapeUrlForCSP( $policyConfig['report-uri'] );
}
} else {
$reportUri = $this->getReportUri( $mode );
}
// Only send an img-src, if we're sending a restricitve default.
if ( !is_array( $defaultSrc )
|| !in_array( '*', $defaultSrc )
|| !in_array( 'data:', $defaultSrc )
|| !in_array( 'blob:', $defaultSrc )
) {
// A future todo might be to make the whitelist options only
// add all the whitelisted sites to the header, instead of
// allowing all (Assuming there is a small number of sites).
// For now, the external image feature disables the limits
// CSP puts on external images.
if ( $mwConfig->get( 'AllowExternalImages' )
|| $mwConfig->get( 'AllowExternalImagesFrom' )
|| $mwConfig->get( 'AllowImageTag' )
) {
$imgSrc = [ '*', 'data:', 'blob:' ];
} elseif ( $mwConfig->get( 'EnableImageWhitelist' ) ) {
$whitelist = wfMessage( 'external_image_whitelist' )
->inContentLanguage()
->plain();
if ( preg_match( '/^\s*[^\s#]/m', $whitelist ) ) {
$imgSrc = [ '*', 'data:', 'blob:' ];
}
}
}
$directives = [];
if ( $scriptSrc ) {
$directives[] = 'script-src ' . implode( ' ', $scriptSrc );
}
if ( $defaultSrc ) {
$directives[] = 'default-src ' . implode( ' ', $defaultSrc );
}
if ( $cssSrc ) {
$directives[] = 'style-src ' . implode( ' ', $cssSrc );
}
if ( $imgSrc ) {
$directives[] = 'img-src ' . implode( ' ', $imgSrc );
}
if ( $reportUri ) {
$directives[] = 'report-uri ' . $reportUri;
}
Hooks::run( 'ContentSecurityPolicyDirectives', [ &$directives, $policyConfig, $mode ] );
return implode( '; ', $directives );
}
/**
* Get the default report uri.
*
* @param int $mode self::*_MODE constant.
* @return string The URI to send reports to.
* @throws UnexpectedValueException if given invalid mode.
*/
private function getReportUri( $mode ) {
$apiArguments = [
'action' => 'cspreport',
'format' => 'json'
];
if ( $mode === self::REPORT_ONLY_MODE ) {
$apiArguments['reportonly'] = '1';
}
$reportUri = wfAppendQuery( wfScript( 'api' ), $apiArguments );
// Per spec, ';' and ',' must be hex-escaped in report uri
// Also add an & at the end of url to work around bug in hhvm
// with handling of POST parameters when always_decode_post_data
// is set to true. See https://github.com/facebook/hhvm/issues/6676
$reportUri = $this->escapeUrlForCSP( $reportUri ) . '&';
return $reportUri;
}
/**
* Given a url, convert to form needed for CSP.
*
* Currently this does either scheme + host, or
* if protocol relative, just the host. Future versions
* could potentially preserve some of the path, if its determined
* that that would be a good idea.
*
* @note This does the extra escaping for CSP, but assumes the url
* has already had normal url escaping applied.
* @note This discards urls same as server name, as 'self' directive
* takes care of that.
* @param string $url
* @return string|bool Converted url or false on failure
*/
private function prepareUrlForCSP( $url ) {
$result = false;
if ( preg_match( '/^[a-z][a-z0-9+.-]*:$/i', $url ) ) {
// A schema source (e.g. blob: or data:)
return $url;
}
$bits = wfParseUrl( $url );
if ( !$bits && strpos( $url, '/' ) === false ) {
// probably something like example.com.
// try again protocol-relative.
$url = '//' . $url;
$bits = wfParseUrl( $url );
}
if ( $bits && isset( $bits['host'] )
&& $bits['host'] !== $this->mwConfig->get( 'ServerName' )
) {
$result = $bits['host'];
if ( $bits['scheme'] !== '' ) {
$result = $bits['scheme'] . $bits['delimiter'] . $result;
}
if ( isset( $bits['port'] ) ) {
$result .= ':' . $bits['port'];
}
$result = $this->escapeUrlForCSP( $result );
}
return $result;
}
/**
* Get additional script sources
*
* @return array Additional sources for loading scripts from
*/
private function getAdditionalSelfUrlsScript() {
$additionalUrls = [];
// wgExtensionAssetsPath for ?debug=true mode
$pathVars = [ 'LoadScript', 'ExtensionAssetsPath', 'ResourceBasePath' ];
foreach ( $pathVars as $path ) {
$url = $this->mwConfig->get( $path );
$preparedUrl = $this->prepareUrlForCSP( $url );
if ( $preparedUrl ) {
$additionalUrls[] = $preparedUrl;
}
}
$RLSources = $this->mwConfig->get( 'ResourceLoaderSources' );
foreach ( $RLSources as $wiki => $sources ) {
foreach ( $sources as $id => $value ) {
$url = $this->prepareUrlForCSP( $value );
if ( $url ) {
$additionalUrls[] = $url;
}
}
}
return array_unique( $additionalUrls );
}
/**
* Get additional host names for the wiki (e.g. if static content loaded elsewhere)
*
* @note These are general load sources, not script sources
* @return array Array of other urls for wiki (for use in default-src)
*/
private function getAdditionalSelfUrls() {
// XXX on a foreign repo, the included description page can have anything on it,
// including inline scripts. But nobody sane does that.
// In principle, you can have even more complex configs... (e.g. The urlsByExt option)
$pathUrls = [];
$additionalSelfUrls = [];
// Future todo: The zone urls should never go into
// style-src. They should either be only in img-src, or if
// img-src unspecified they should be in default-src. Similarly,
// the DescriptionStylesheetUrl only needs to be in style-src
// (or default-src if style-src unspecified).
$callback = function ( $repo, &$urls ) {
$urls[] = $repo->getZoneUrl( 'public' );
$urls[] = $repo->getZoneUrl( 'transcoded' );
$urls[] = $repo->getZoneUrl( 'thumb' );
$urls[] = $repo->getDescriptionStylesheetUrl();
};
$localRepo = RepoGroup::singleton()->getRepo( 'local' );
$callback( $localRepo, $pathUrls );
RepoGroup::singleton()->forEachForeignRepo( $callback, [ &$pathUrls ] );
// Globals that might point to a different domain
$pathGlobals = [ 'LoadScript', 'ExtensionAssetsPath', 'StylePath', 'ResourceBasePath' ];
foreach ( $pathGlobals as $path ) {
$pathUrls[] = $this->mwConfig->get( $path );
}
foreach ( $pathUrls as $path ) {
$preparedUrl = $this->prepareUrlForCSP( $path );
if ( $preparedUrl !== false ) {
$additionalSelfUrls[] = $preparedUrl;
}
}
$RLSources = $this->mwConfig->get( 'ResourceLoaderSources' );
foreach ( $RLSources as $wiki => $sources ) {
foreach ( $sources as $id => $value ) {
$url = $this->prepareUrlForCSP( $value );
if ( $url ) {
$additionalSelfUrls[] = $url;
}
}
}
return array_unique( $additionalSelfUrls );
}
/**
* include domains that are allowed to send us CORS requests.
*
* Technically, $wgCrossSiteAJAXdomains lists things that are allowed to talk to us
* not things that we are allowed to talk to - but if something is allowed to talk to us,
* then there is a good chance that we should probably be allowed to talk to it.
*
* This is configurable with the 'includeCORS' key in the CSP config, and enabled
* by default.
* @note CORS domains with single character ('?') wildcards, are not included.
* @return array Additional hosts
*/
private function getCORSSources() {
$additionalUrls = [];
$CORSSources = $this->mwConfig->get( 'CrossSiteAJAXdomains' );
foreach ( $CORSSources as $source ) {
if ( strpos( $source, '?' ) !== false ) {
// CSP doesn't support single char wildcard
continue;
}
$url = $this->prepareUrlForCSP( $source );
if ( $url ) {
$additionalUrls[] = $url;
}
}
return $additionalUrls;
}
/**
* CSP spec says ',' and ';' are not allowed to appear in urls.
*
* @note This assumes that normal escaping has been applied to the url
* @param string $url URL (or possibly just part of one)
* @return string
*/
private function escapeUrlForCSP( $url ) {
return str_replace(
[ ';', ',' ],
[ '%3B', '%2C' ],
$url
);
}
/**
* Does this browser give false positive reports?
*
* Some versions of firefox (40-42) incorrectly report a csp
* violation for nonce sources, despite allowing them.
*
* @see https://bugzilla.mozilla.org/show_bug.cgi?id=1026520
* @param string $ua User-agent header
* @return bool
*/
public static function falsePositiveBrowser( $ua ) {
return (bool)preg_match( '!Firefox/4[0-2]\.!', $ua );
}
/**
* Should we set nonce attribute
*
* @param Config $config Configuration object
* @return bool
*/
public static function isNonceRequired( Config $config ) {
$configs = [
$config->get( 'CSPHeader' ),
$config->get( 'CSPReportOnlyHeader' )
];
foreach ( $configs as $headerConfig ) {
if (
$headerConfig === true ||
( is_array( $headerConfig ) &&
!isset( $headerConfig['useNonces'] ) ) ||
( is_array( $headerConfig ) &&
isset( $headerConfig['useNonces'] ) &&
$headerConfig['useNonces'] )
) {
return true;
}
}
return false;
}
}
Zerion Mini Shell 1.0