Bug #5856: Do not expose physical screen info via window & window.screen. (c2c40e3d) · Commits · The Tor Project / Applications / Tor Browser

dom/base/nsDOMWindowUtils.cpp

+7 −3

Original line number	Diff line number	Diff line
		@@ -2070,9 +2070,13 @@ nsDOMWindowUtils::GetViewId(nsIDOMElement* aElement, nsViewID* aResult)
		NS_IMETHODIMP
		nsDOMWindowUtils::GetScreenPixelsPerCSSPixel(float* aScreenPixels)
		{
		nsCOMPtr<nsPIDOMWindow> window = do_QueryReferent(mWindow);
		NS_ENSURE_TRUE(window, NS_ERROR_FAILURE);
		return window->GetDevicePixelRatio(aScreenPixels);
		// We don't call nsGlobalWindow::GetDevicePixelRatio() in case it is
		// being spoofed to satisfy the "privacy.resistFingerprinting" pref.
		nsPresContext* presContext = GetPresContext();
		*aScreenPixels = !presContext ? 1.0 :
		(float(nsPresContext::AppUnitsPerCSSPixel())/
		presContext->AppUnitsPerDevPixel());
		return NS_OK;
		}

		NS_IMETHODIMP

dom/base/nsGlobalWindow.cpp

+36 −0

Original line number	Diff line number	Diff line
		@@ -4971,6 +4971,12 @@ nsGlobalWindow::GetOuterSize(ErrorResult& aError)
		{
		MOZ_ASSERT(IsOuterWindow());

		if (!IsChrome()) {
		CSSIntSize size;
		aError = GetInnerSize(size);
		return nsIntSize(size.width, size.height);
		}

		nsCOMPtr<nsIBaseWindow> treeOwnerAsWin = GetTreeOwnerWindow();
		if (!treeOwnerAsWin) {
		aError.Throw(NS_ERROR_FAILURE);
		@@ -5102,6 +5108,11 @@ nsGlobalWindow::GetScreenXY(ErrorResult& aError)
		{
		MOZ_ASSERT(IsOuterWindow());

		// For non-chrome callers, always return (0,0) to prevent fingerprinting.
		if (!IsChrome()) {
		return nsIntPoint(0, 0);
		}

		nsCOMPtr<nsIBaseWindow> treeOwnerAsWin = GetTreeOwnerWindow();
		if (!treeOwnerAsWin) {
		aError.Throw(NS_ERROR_FAILURE);
		@@ -5166,6 +5177,9 @@ nsGlobalWindow::GetMozInnerScreenX(ErrorResult& aError)
		{
		FORWARD_TO_OUTER_OR_THROW(GetMozInnerScreenX, (aError), aError, 0);

		// For non-chrome callers, always return 0 to prevent fingerprinting.
		if (!IsChrome()) return 0.0;

		nsRect r = GetInnerScreenRect();
		return nsPresContext::AppUnitsToFloatCSSPixels(r.x);
		}
		@@ -5184,6 +5198,9 @@ nsGlobalWindow::GetMozInnerScreenY(ErrorResult& aError)
		{
		FORWARD_TO_OUTER_OR_THROW(GetMozInnerScreenY, (aError), aError, 0);

		// For non-chrome callers, always return 0 to prevent fingerprinting.
		if (!IsChrome()) return 0.0;

		nsRect r = GetInnerScreenRect();
		return nsPresContext::AppUnitsToFloatCSSPixels(r.y);
		}
		@@ -5202,6 +5219,11 @@ nsGlobalWindow::GetDevicePixelRatio(ErrorResult& aError)
		{
		FORWARD_TO_OUTER_OR_THROW(GetDevicePixelRatio, (aError), aError, 0.0);

		// For non-chrome callers, always return 1.0 to prevent fingerprinting.
		if (!IsChrome()) {
		return 1.0;
		}

		if (!mDocShell) {
		return 1.0;
		}
		@@ -5507,6 +5529,20 @@ nsGlobalWindow::SetScreenY(int32_t aScreenY)
		return rv.ErrorCode();
		}

		bool
		nsGlobalWindow::IsChrome() const
		{
		bool isChrome = false;

		if (mDocShell) {
		nsRefPtr<nsPresContext> presContext;
		mDocShell->GetPresContext(getter_AddRefs(presContext));
		isChrome = (presContext && presContext->IsChrome());
		}

		return isChrome;
		}

		// NOTE: Arguments to this function should have values scaled to
		// CSS pixels, not device pixels.
		void

dom/base/nsGlobalWindow.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -599,6 +599,8 @@ public:
		return mIsChrome;
		}

		bool IsChrome() const;

		using nsPIDOMWindow::IsModalContentWindow;
		static bool IsModalContentWindow(JSContext* aCx, JSObject* aGlobal);

dom/base/nsScreen.cpp

+49 −0

Original line number	Diff line number	Diff line
		@@ -67,6 +67,9 @@ NS_IMPL_RELEASE_INHERITED(nsScreen, DOMEventTargetHelper)
		int32_t
		nsScreen::GetPixelDepth(ErrorResult& aRv)
		{
		// For non-chrome callers, always return 24 to prevent fingerprinting.
		if (!IsChrome()) return 24;

		nsDeviceContext* context = GetDeviceContext();

		if (!context) {
		@@ -110,6 +113,9 @@ nsScreen::GetDeviceContext()
		nsresult
		nsScreen::GetRect(nsRect& aRect)
		{
		// For non-chrome callers, return window inner rect to prevent fingerprinting.
		if (!IsChrome()) return GetWindowInnerRect(aRect);

		nsDeviceContext *context = GetDeviceContext();

		if (!context) {
		@@ -129,6 +135,9 @@ nsScreen::GetRect(nsRect& aRect)
		nsresult
		nsScreen::GetAvailRect(nsRect& aRect)
		{
		// For non-chrome callers, return window inner rect to prevent fingerprinting.
		if (!IsChrome()) return GetWindowInnerRect(aRect);

		nsDeviceContext *context = GetDeviceContext();

		if (!context) {
		@@ -372,3 +381,43 @@ nsScreen::FullScreenEventListener::HandleEvent(nsIDOMEvent* aEvent)

		return NS_OK;
		}

		bool
		nsScreen::IsChrome()
		{
		nsCOMPtr<nsPIDOMWindow> owner = GetOwner();
		if (owner && owner->GetDocShell()) {
		return owner->GetDocShell()->ItemType() == nsIDocShellTreeItem::typeChrome;
		}
		return false;
		}

		nsresult
		nsScreen::GetDOMWindow(nsIDOMWindow **aResult)
		{
		NS_ENSURE_ARG_POINTER(aResult);
		*aResult = NULL;

		nsCOMPtr<nsPIDOMWindow> owner = GetOwner();
		if (!owner)
		return NS_ERROR_FAILURE;

		nsCOMPtr<nsIDOMWindow> win = do_QueryInterface(owner);
		NS_ENSURE_STATE(win);
		win.swap(*aResult);

		return NS_OK;
		}

		nsresult
		nsScreen::GetWindowInnerRect(nsRect& aRect)
		{
		aRect.x = 0;
		aRect.y = 0;
		nsCOMPtr<nsIDOMWindow> win;
		nsresult rv = GetDOMWindow(getter_AddRefs(win));
		NS_ENSURE_SUCCESS(rv, rv);
		rv = win->GetInnerWidth(&aRect.width);
		NS_ENSURE_SUCCESS(rv, rv);
		return win->GetInnerHeight(&aRect.height);
		}

dom/base/nsScreen.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -130,6 +130,9 @@ protected:
		nsDeviceContext* GetDeviceContext();
		nsresult GetRect(nsRect& aRect);
		nsresult GetAvailRect(nsRect& aRect);
		bool IsChrome();
		nsresult GetDOMWindow(nsIDOMWindow **aResult);
		nsresult GetWindowInnerRect(nsRect& aRect);

		mozilla::dom::ScreenOrientation mOrientation;