Bug 1215167 - Forbid unsafe browser CPOWs (disabled by default for now) (r=mrbkap)

dom/base/test/chrome/cpows_child.js

@@ -20,6 +20,7 @@ var Cu = Components.utils;
     lifetime_test,
     cancel_test,
     cancel_test2,
+    unsafe_test,
   ];
 
   function go() {
@@ -337,3 +338,20 @@ function cancel_test2(finish)
     if (fin1 && fin2) finish();
   });
 }
+
+function unsafe_test(finish)
+{
+  if (!is_remote) {
+    // Only run this test when running out-of-process.
+    finish();
+    return;
+  }
+
+  function f() {}
+
+  sendAsyncMessage("cpows:unsafe", null, {f});
+  addMessageListener("cpows:unsafe_done", msg => {
+    sendRpcMessage("cpows:safe", null, {f});
+    addMessageListener("cpows:safe_done", finish);
+  });
+}

dom/base/test/chrome/cpows_parent.xul

@@ -390,6 +390,33 @@
       msg.target.messageManager.sendAsyncMessage("cpows:cancel_test2_done");
     }
 
+    function recvUnsafe(msg) {
+      let failed = false;
+
+      const PREF_UNSAFE_FORBIDDEN = "dom.ipc.cpows.forbid-unsafe-from-browser";
+      opener.wrappedJSObject.SpecialPowers.setBoolPref(PREF_UNSAFE_FORBIDDEN, true);
+      try {
+        msg.objects.f();
+      } catch (e if /unsafe CPOW usage forbidden/.test(String(e))) {
+        failed = true;
+      }
+      opener.wrappedJSObject.SpecialPowers.clearUserPref(PREF_UNSAFE_FORBIDDEN);
+      ok(failed, "CPOW should fail when unsafe");
+      msg.target.messageManager.sendAsyncMessage("cpows:unsafe_done");
+    }
+
+    function recvSafe(msg) {
+      const PREF_UNSAFE_FORBIDDEN = "dom.ipc.cpows.forbid-unsafe-from-browser";
+      opener.wrappedJSObject.SpecialPowers.setBoolPref(PREF_UNSAFE_FORBIDDEN, true);
+      try {
+        msg.objects.f();
+      } catch (e if /unsafe CPOW usage forbidden/.test(String(e))) {
+        ok(false, "cpow failed");
+      }
+      opener.wrappedJSObject.SpecialPowers.clearUserPref(PREF_UNSAFE_FORBIDDEN);
+      msg.target.messageManager.sendAsyncMessage("cpows:safe_done");
+    }
+
     function run_tests(type) {
       info("Running tests: " + type);
       var node = document.getElementById('cpowbrowser_' + type);
@@ -429,6 +456,8 @@
       mm.addMessageListener("cpows:cancel_test", recvCancelTest);
       mm.addMessageListener("cpows:cancel_sync_message", recvCancelSyncMessage);
       mm.addMessageListener("cpows:cancel_test2", recvCancelTest2);
+      mm.addMessageListener("cpows:unsafe", recvUnsafe);
+      mm.addMessageListener("cpows:safe", recvSafe);
       mm.loadFrameScript("chrome://mochitests/content/chrome/dom/base/test/chrome/cpows_child.js", true);
     }
 

dom/ipc/ContentParent.cpp

@@ -1894,28 +1894,6 @@ ContentParent::OnChannelError()
     PContentParent::OnChannelError();
 }
 
-void
-ContentParent::OnBeginSyncTransaction() {
-    if (XRE_IsParentProcess()) {
-        nsCOMPtr<nsIConsoleService> console(do_GetService(NS_CONSOLESERVICE_CONTRACTID));
-        JSContext *cx = nsContentUtils::GetCurrentJSContext();
-        if (!sDisableUnsafeCPOWWarnings) {
-            if (console && cx) {
-                nsAutoString filename;
-                uint32_t lineno = 0, column = 0;
-                nsJSUtils::GetCallingLocation(cx, filename, &lineno, &column);
-                nsCOMPtr<nsIScriptError> error(do_CreateInstance(NS_SCRIPTERROR_CONTRACTID));
-                error->Init(NS_LITERAL_STRING("unsafe CPOW usage"), filename,
-                            EmptyString(), lineno, column,
-                            nsIScriptError::warningFlag, "chrome javascript");
-                console->LogMessage(error);
-            } else {
-                NS_WARNING("Unsafe synchronous IPC message");
-            }
-        }
-    }
-}
-
 void
 ContentParent::OnChannelConnected(int32_t pid)
 {

dom/ipc/ContentParent.h

@@ -325,8 +325,6 @@ public:
 
     virtual void OnChannelError() override;
 
-    virtual void OnBeginSyncTransaction() override;
-
     virtual PCrashReporterParent*
     AllocPCrashReporterParent(const NativeThreadId& tid,
                               const uint32_t& processType) override;

ipc/glue/MessageChannel.cpp

@@ -848,9 +848,6 @@ MessageChannel::Send(Message* aMsg, Message* aReply)
     AssertWorkerThread();
     mMonitor->AssertNotCurrentThreadOwns();
 
-    if (mCurrentTransaction == 0)
-        mListener->OnBeginSyncTransaction();
-
 #ifdef OS_WIN
     SyncStackFrame frame(this, false);
     NeuteredWindowRegion neuteredRgn(mFlags & REQUIRE_DEFERRED_MESSAGE_PROTECTION);

ipc/glue/MessageChannel.h

@@ -143,6 +143,7 @@ class MessageChannel : HasResultCodes
         return !mCxxStackFrames.empty();
     }
 
+    bool IsInTransaction() const { return mCurrentTransaction != 0; }
     void CancelCurrentTransaction();
 
     /**

ipc/glue/MessageLink.h

@@ -88,10 +88,6 @@ class MessageListener
     virtual void OnExitedCall() {
         NS_RUNTIMEABORT("default impl shouldn't be invoked");
     }
-    /* This callback is called when a sync message is sent that begins a new IPC transaction
-       (i.e., when it is not part of an existing sequence of nested messages). */
-    virtual void OnBeginSyncTransaction() {
-    }
     virtual RacyInterruptPolicy MediateInterruptRace(const Message& parent,
                                                      const Message& child)
     {

js/ipc/JavaScriptChild.h

@@ -25,6 +25,8 @@ class JavaScriptChild : public JavaScriptBase<PJavaScriptChild>
 
     void drop(JSObject* obj);
 
+    bool allowMessage(JSContext* cx) override { return true; }
+
   protected:
     virtual bool isParent() override { return false; }
     virtual JSObject* scopeForTargetObjects() override;

js/ipc/JavaScriptParent.cpp

@@ -48,6 +48,54 @@ JavaScriptParent::init()
     return true;
 }
 
+static bool
+ForbidUnsafeBrowserCPOWs()
+{
+    static bool result;
+    static bool cached = false;
+    if (!cached) {
+        cached = true;
+        Preferences::AddBoolVarCache(&result, "dom.ipc.cpows.forbid-unsafe-from-browser", false);
+    }
+    return result;
+}
+
+bool
+JavaScriptParent::allowMessage(JSContext* cx)
+{
+    MessageChannel* channel = GetIPCChannel();
+    if (channel->IsInTransaction())
+        return true;
+
+    if (ForbidUnsafeBrowserCPOWs()) {
+        if (JSObject* global = JS::CurrentGlobalOrNull(cx)) {
+            if (!JS::AddonIdOfObject(global)) {
+                JS_ReportError(cx, "unsafe CPOW usage forbidden");
+                return false;
+            }
+        }
+    }
+
+    static bool disableUnsafeCPOWWarnings = PR_GetEnv("DISABLE_UNSAFE_CPOW_WARNINGS");
+    if (!disableUnsafeCPOWWarnings) {
+        nsCOMPtr<nsIConsoleService> console(do_GetService(NS_CONSOLESERVICE_CONTRACTID));
+        if (console && cx) {
+            nsAutoString filename;
+            uint32_t lineno = 0, column = 0;
+            nsJSUtils::GetCallingLocation(cx, filename, &lineno, &column);
+            nsCOMPtr<nsIScriptError> error(do_CreateInstance(NS_SCRIPTERROR_CONTRACTID));
+            error->Init(NS_LITERAL_STRING("unsafe CPOW usage"), filename,
+                        EmptyString(), lineno, column,
+                        nsIScriptError::warningFlag, "chrome javascript");
+            console->LogMessage(error);
+        } else {
+            NS_WARNING("Unsafe synchronous IPC message");
+        }
+    }
+
+    return true;
+}
+
 void
 JavaScriptParent::trace(JSTracer* trc)
 {

js/ipc/JavaScriptParent.h

@@ -25,6 +25,8 @@ class JavaScriptParent : public JavaScriptBase<PJavaScriptParent>
 
     void drop(JSObject* obj);
 
+    bool allowMessage(JSContext* cx) override;
+
     mozilla::ipc::IProtocol*
     CloneProtocol(Channel* aChannel, ProtocolCloneContext* aCtx) override;
 

js/ipc/WrapperOwner.cpp

@@ -150,6 +150,9 @@ const CPOWProxyHandler CPOWProxyHandler::singleton;
         JS_ReportError(cx, "cannot use a CPOW whose process is gone");  \
         return false;                                                   \
     }                                                                   \
+    if (!owner->allowMessage(cx)) {                                     \
+        return false;                                                   \
+    }                                                                   \
     {                                                                   \
         CPOWTimer timer(cx);                                            \
         return owner->call args;                                        \

js/ipc/WrapperOwner.h

@@ -74,6 +74,8 @@ class WrapperOwner : public virtual JavaScriptShared
 
     bool active() { return !inactive_; }
 
+    virtual bool allowMessage(JSContext* cx) = 0;
+
     void drop(JSObject* obj);
     void updatePointer(JSObject* obj, const JSObject* old);