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[BUGFIX] Support Visual Editor with restrictive CSP #119

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[BUGFIX] Support Visual Editor with restrictive CSP #119

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104 changes: 100 additions & 4 deletions Classes/EventListener/PolicyMutatedEventListener.php
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Original file line number Diff line number Diff line change
Expand Up @@ -9,9 +9,15 @@
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\Directive;
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\Event\PolicyMutatedEvent;
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\Event\PolicyPreparedEvent;
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\HashProxy;
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\HashValue;
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\RawValue;
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\SourceKeyword;
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\SourceScheme;
use TYPO3\CMS\VisualEditor\Service\EditModeService;

use function str_starts_with;

final readonly class PolicyMutatedEventListener
{
public function __construct(
Expand Down Expand Up @@ -55,14 +61,104 @@ public function __invoke(PolicyMutatedEvent $event): void

$policy = $event->getCurrentPolicy();

// we add all necessary CSP rules, so even if someone sets all Directives to 'none' we have a working Editor.

// add style-src 'unsafe-inline' to allow a working ckeditor in the frontend.
$policy = $policy->reduce(Directive::StyleSrc, SourceKeyword::nonceProxy); // to allow 'unsafe-inline' we first need to remove the nonces
$policy = $policy->reduce(Directive::StyleSrc, SourceKeyword::nonceProxy, SourceKeyword::none); // to allow 'unsafe-inline' we first need to remove the nonces
$policy = $policy->extend(Directive::StyleSrc, SourceKeyword::self, SourceKeyword::unsafeInline);

if ($policy->has(Directive::StyleSrcAttr)) {
// add the same to StyleSrcAttr if that is present
$policy = $policy->reduce(Directive::StyleSrcAttr, SourceKeyword::nonceProxy); // to allow 'unsafe-inline' we first need to remove the nonces
$policy = $policy->extend(Directive::StyleSrcAttr, SourceKeyword::unsafeInline);
// add the same to StyleSrcAttr if that is present (fallback chain otherwise)
$policy = $policy->reduce(Directive::StyleSrcAttr, SourceKeyword::nonceProxy, SourceKeyword::none); // to allow 'unsafe-inline' we first need to remove the nonces
$policy = $policy->extend(Directive::StyleSrcAttr, SourceKeyword::unsafeInline); // no self as that is not a thing for style-src-attr
}

if ($policy->has(Directive::StyleSrcElem)) {
// add the same to StyleSrcElem if that is present (fallback chain otherwise)
$policy = $policy->reduce(Directive::StyleSrcElem, SourceKeyword::nonceProxy, SourceKeyword::none); // to allow 'unsafe-inline' we first need to remove the nonces
$policy = $policy->extend(Directive::StyleSrcElem, SourceKeyword::self, SourceKeyword::unsafeInline);
}

$policy = $policy->reduce(Directive::ScriptSrc, SourceKeyword::nonceProxy, SourceKeyword::none);
$policy = $policy->extend(Directive::ScriptSrc, SourceKeyword::self, SourceKeyword::unsafeInline);

if ($policy->has(Directive::ScriptSrcElem)) {
$policy = $policy->reduce(Directive::ScriptSrcElem, SourceKeyword::nonceProxy, SourceKeyword::none);
$policy = $policy->extend(Directive::ScriptSrcElem, SourceKeyword::self, SourceKeyword::unsafeInline);
}


if ($policy->has(Directive::ImgSrc)) {
$policy = $policy->reduce(Directive::ImgSrc, SourceKeyword::none);
$policy = $policy->extend(Directive::ImgSrc, SourceKeyword::self, SourceScheme::data);
}

if ($policy->has(Directive::FontSrc)) {
$policy = $policy->reduce(Directive::FontSrc, SourceKeyword::none);
$policy = $policy->extend(Directive::FontSrc, SourceKeyword::self);
}

if ($policy->has(Directive::FrameAncestors)) {
$policy = $policy->reduce(Directive::FrameAncestors, SourceKeyword::none);
$policy = $policy->extend(Directive::FrameAncestors, SourceKeyword::self);
}

if ($policy->has(Directive::ConnectSrc)) {
$policy = $policy->reduce(Directive::ConnectSrc, SourceKeyword::none);
$policy = $policy->extend(Directive::ConnectSrc, SourceKeyword::self);
}

if ($policy->has(Directive::TrustedTypes)) {
$policy = $policy->reduce(Directive::TrustedTypes, SourceKeyword::none);
$policy = $policy->extend(Directive::TrustedTypes, new RawValue('lit-html'));
}

if ($policy->has(Directive::RequireTrustedTypesFor)) {
$policy = $policy->remove(Directive::RequireTrustedTypesFor);
}

if ($policy->has(Directive::Sandbox)) {
$policy = $policy->remove(Directive::Sandbox);
}

// filter out all hashs and nonces
foreach (Directive::cases() as $directive) {
if (!$policy->has($directive)) {
continue;
}

$sources = [];
foreach ($policy->get($directive)->sources ?? [] as $source) {
if ($source instanceof HashValue) {
continue;
}

if ($source instanceof HashProxy) {
continue;
}

if ($source instanceof RawValue) {
if (str_starts_with((string)$source, "'sha256-")) {
continue;
}

if (str_starts_with((string)$source, "'sha384-")) {
continue;
}

if (str_starts_with((string)$source, "'sha512-")) {
continue;
}

if (str_starts_with((string)$source, "'nonce-")) {
continue;
}
}

$sources[] = $source;
}

$policy = $policy->set($directive, ...$sources);
}

$event->setCurrentPolicy($policy);
Expand Down