Bug 1453869 part 7. Make the DOMParser WebIDL constructor use a nullp…

…rincipal for the document if the caller is system-principal. r=mrbkap In our test suite, we only run into two calls to this constructor with a system principal, and both are in test code. After this, calling the WebIDL constructor from system code is _almost_ equivalent to creating by contract. The one difference is that the resulting DOMParser (and the documents it creates) will have its script handling object set to the global the constructor came from instead of being null. MozReview-Commit-ID: Fe2yMeqoYnB
EtlerEdelgard · Apr 21, 2018 · c2c0695 · c2c0695
1 parent df65914
commit c2c0695
Showing 1 changed file with 14 additions and 3 deletions.
diff --git a/dom/base/DOMParser.cpp b/dom/base/DOMParser.cpp
@@ -9,6 +9,7 @@
 #include "nsIDOMDocument.h"
 #include "nsNetUtil.h"
 #include "nsDOMString.h"
+#include "MainThreadUtils.h"
 #include "nsIStreamListener.h"
 #include "nsStringStream.h"
 #include "nsIScriptError.h"
@@ -296,10 +297,20 @@ DOMParser::Init(nsIPrincipal* principal, nsIURI* documentURI,
 DOMParser::Constructor(const GlobalObject& aOwner,
                        ErrorResult& rv)
 {
+  MOZ_ASSERT(NS_IsMainThread());
   RefPtr<DOMParser> domParser = new DOMParser(aOwner.GetAsSupports());
-  rv = domParser->InitInternal(aOwner.GetAsSupports(),
-                               nsContentUtils::SubjectPrincipal(),
-                               nullptr, nullptr);
+
+  nsCOMPtr<nsIPrincipal> docPrincipal = aOwner.GetSubjectPrincipal();
+  if (nsContentUtils::IsSystemPrincipal(docPrincipal)) {
+    docPrincipal = NullPrincipal::CreateWithoutOriginAttributes();
+    // Call Init() directly so we don't pick up our window's URI and
+    // base URI, for backwards compat.
+    nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aOwner.GetAsSupports());
+    rv = domParser->Init(docPrincipal, nullptr, nullptr, global);
+  } else {
+    rv = domParser->InitInternal(aOwner.GetAsSupports(), docPrincipal,
+                                 nullptr, nullptr);
+  }
   if (rv.Failed()) {
     return nullptr;
   }