Bug 1522181 - multiple external protocol URL blocker behind pref, r=smaug

docshell/base/nsDocShell.cpp

@@ -9640,6 +9640,7 @@ nsresult nsDocShell::DoURILoad(nsDocShellLoadState* aLoadState,
                    aContentPolicyType == nsIContentPolicy::TYPE_INTERNAL_FRAME,
                "DoURILoad thinks this is a frame and InternalLoad does not");
 
+    if (StaticPrefs::dom_block_external_protocol_in_iframes()) {
       // Only allow URLs able to return data in iframes.
       bool doesNotReturnData = false;
       NS_URIChainHasFlags(aLoadState->URI(),
@@ -9648,8 +9649,9 @@ nsresult nsDocShell::DoURILoad(nsDocShellLoadState* aLoadState,
       if (doesNotReturnData) {
         bool popupBlocked = true;
 
-      // Let's consider external protocols as popups and let's check if the page
-      // is allowed to open them without abuse regardless of allowed events
+        // Let's consider external protocols as popups and let's check if the
+        // page is allowed to open them without abuse regardless of allowed
+        // events
         if (PopupBlocker::GetPopupControlState() <= PopupBlocker::openBlocked) {
           popupBlocked = !PopupBlocker::TryUsePopupOpeningToken();
         } else {
@@ -9665,6 +9667,7 @@ nsresult nsDocShell::DoURILoad(nsDocShellLoadState* aLoadState,
           return NS_ERROR_UNKNOWN_PROTOCOL;
         }
       }
+    }
 
     // Only allow view-source scheme in top-level docshells. view-source is
     // the only scheme to which this applies at the moment due to potential

dom/html/test/test_external_protocol_iframe.html

@@ -10,8 +10,7 @@
   <div id='foo'><a href='#'>Click here to test this issue</a></div>
   <script>
 
-SimpleTest.waitForExplicitFinish();
-
+function next() {
   let foo = document.getElementById('foo');
   foo.addEventListener('click', _ => {
     is(ChromeUtils.getPopupControlState(), "openAllowed", "Click events allow popups");
@@ -33,7 +32,13 @@ foo.addEventListener('click', _ => {
   setTimeout(_ => {
     sendMouseEvent({type:'click'}, 'foo');
   }, 0);
+}
 
+SpecialPowers.pushPrefEnv({'set': [
+  ['dom.block_external_protocol_in_iframes', true],
+]}, next);
+
+SimpleTest.waitForExplicitFinish();
   </script>
 </body>
 </html>

modules/libpref/init/StaticPrefList.h

@@ -456,6 +456,19 @@ VARCACHE_PREF(
   RelaxedAtomicBool, false
 )
 
+// Block multiple external protocol URLs in iframes per single event.
+#ifdef NIGHTLY_BUILD
+#define PREF_VALUE true
+#else
+#define PREF_VALUE false
+#endif
+VARCACHE_PREF(
+  "dom.block_external_protocol_in_iframes",
+   dom_block_external_protocol_in_iframes,
+  bool, PREF_VALUE
+)
+#undef PREF_VALUE
+
 // Block multiple window.open() per single event.
 VARCACHE_PREF(
   "dom.block_multiple_popups",