LibWeb/CSP: Implement the style-src-elem directive

Author: https://github.com/Lubrsi
Commit: 574b736156
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5490
Reviewed-by: https://github.com/shannonbooth ✅

Libraries/LibWeb/ContentSecurityPolicy/Directives/StyleSourceElementDirective.cpp

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2024, Luke Wilde <luke@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/ContentSecurityPolicy/Directives/DirectiveOperations.h>
+#include <LibWeb/ContentSecurityPolicy/Directives/Names.h>
+#include <LibWeb/ContentSecurityPolicy/Directives/StyleSourceElementDirective.h>
+#include <LibWeb/Fetch/Infrastructure/HTTP/Requests.h>
+
+namespace Web::ContentSecurityPolicy::Directives {
+
+GC_DEFINE_ALLOCATOR(StyleSourceElementDirective);
+
+StyleSourceElementDirective::StyleSourceElementDirective(String name, Vector<String> value)
+    : Directive(move(name), move(value))
+{
+}
+
+// https://w3c.github.io/webappsec-csp/#style-src-elem-pre-request
+Directive::Result StyleSourceElementDirective::pre_request_check(GC::Heap&, GC::Ref<Fetch::Infrastructure::Request const> request, GC::Ref<Policy const> policy) const
+{
+    // 1. Let name be the result of executing § 6.8.1 Get the effective directive for request on request.
+    auto name = get_the_effective_directive_for_request(request);
+
+    // 2. If the result of executing § 6.8.4 Should fetch directive execute on name, style-src-elem and policy is "No",
+    //    return "Allowed".
+    if (should_fetch_directive_execute(name, Names::StyleSrcElem, policy) == ShouldExecute::No)
+        return Result::Allowed;
+
+    // 3. If the result of executing § 6.7.2.3 Does nonce match source list? on request’s cryptographic nonce metadata
+    //    and this directive’s value is "Matches", return "Allowed".
+    if (does_nonce_match_source_list(request->cryptographic_nonce_metadata(), value()) == MatchResult::Matches)
+        return Result::Allowed;
+
+    // 4. If the result of executing § 6.7.2.5 Does request match source list? on request, this directive’s value, and
+    //    policy, is "Does Not Match", return "Blocked".
+    if (does_request_match_source_list(request, value(), policy) == MatchResult::DoesNotMatch)
+        return Result::Blocked;
+
+    // 5. Return "Allowed".
+    return Result::Allowed;
+}
+
+// https://w3c.github.io/webappsec-csp/#style-src-elem-post-request
+Directive::Result StyleSourceElementDirective::post_request_check(GC::Heap&, GC::Ref<Fetch::Infrastructure::Request const> request, GC::Ref<Fetch::Infrastructure::Response const> response, GC::Ref<Policy const> policy) const
+{
+    // 1. Let name be the result of executing § 6.8.1 Get the effective directive for request on request.
+    auto name = get_the_effective_directive_for_request(request);
+
+    // 2. If the result of executing § 6.8.4 Should fetch directive execute on name, style-src-elem and policy is "No",
+    //    return "Allowed".
+    if (should_fetch_directive_execute(name, Names::StyleSrcElem, policy) == ShouldExecute::No)
+        return Result::Allowed;
+
+    // 3. If the result of executing § 6.7.2.3 Does nonce match source list? on request’s cryptographic nonce metadata
+    //    and this directive’s value is "Matches", return "Allowed".
+    if (does_nonce_match_source_list(request->cryptographic_nonce_metadata(), value()) == MatchResult::Matches)
+        return Result::Allowed;
+
+    // 4. If the result of executing § 6.7.2.6 Does response to request match source list? on response, request, this
+    //    directive’s value, and policy, is "Does Not Match", return "Blocked".
+    if (does_response_match_source_list(response, request, value(), policy) == MatchResult::DoesNotMatch)
+        return Result::Blocked;
+
+    // 5. Return "Allowed".
+    return Result::Allowed;
+}
+
+// https://w3c.github.io/webappsec-csp/#style-src-elem-inline
+Directive::Result StyleSourceElementDirective::inline_check(GC::Heap&, GC::Ptr<DOM::Element const> element, InlineType type, GC::Ref<Policy const> policy, String const& source) const
+{
+    // 1. Let name be the result of executing § 6.8.2 Get the effective directive for inline checks on type.
+    auto name = get_the_effective_directive_for_inline_checks(type);
+
+    // 2. If the result of executing § 6.8.4 Should fetch directive execute on name, style-src-elem and policy is "No",
+    //    return "Allowed".
+    if (should_fetch_directive_execute(name, Names::StyleSrcElem, policy) == ShouldExecute::No)
+        return Result::Allowed;
+
+    // 3. If the result of executing § 6.7.3.3 Does element match source list for type and source? on element, this
+    //    directive’s value, type, and source, is "Does Not Match", return "Blocked".
+    if (does_element_match_source_list_for_type_and_source(element, value(), type, source) == MatchResult::DoesNotMatch)
+        return Result::Blocked;
+
+    // 4. Return "Allowed".
+    return Result::Allowed;
+}
+
+}