From f343265a289724c81017f089c024a7618267c4e3 Mon Sep 17 00:00:00 2001
From: Eamon Walsh <ewalsh@tycho.nsa.gov>
Date: Fri, 15 Feb 2008 19:53:45 -0500
Subject: [PATCH] XACE: Make the default window background state configurable
 per-window.

To recap: the original XC-SECURITY extension disallowed background "None" if
the window was untrusted.  XACE 1.0 preserved this check as a hook function.
XACE pre-2.0 removed the hook and first abolished background "None entirely,
then restored it as a global on/off switch in response to Bug #13683.
Now it's back to being per-window, via a flag instead of a hook function.
---
 Xext/security.c     | 5 +++++
 Xext/xace.h         | 4 ++--
 dix/window.c        | 9 +++++----
 include/windowstr.h | 1 +
 4 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/Xext/security.c b/Xext/security.c
index a3cde2cec..27ef38205 100644
--- a/Xext/security.c
+++ b/Xext/security.c
@@ -810,6 +810,11 @@ SecurityResource(CallbackListPtr *pcbl, pointer unused, pointer calldata)
     subj = dixLookupPrivate(&rec->client->devPrivates, stateKey);
     obj = dixLookupPrivate(&clients[cid]->devPrivates, stateKey);
 
+    /* disable background None for untrusted windows */
+    if ((requested & DixCreateAccess) && (rec->rtype == RT_WINDOW))
+	if (subj->haveState && subj->trustLevel != XSecurityClientTrusted)
+	    ((WindowPtr)rec->res)->forcedBG = TRUE;
+
     /* special checks for server-owned resources */
     if (cid == 0) {
 	if (rec->rtype & RC_DRAWABLE)
diff --git a/Xext/xace.h b/Xext/xace.h
index 2016ca322..1f07d9fd2 100644
--- a/Xext/xace.h
+++ b/Xext/xace.h
@@ -31,7 +31,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #include "property.h"
 
 /* Default window background */
-#define XaceBackgroundNoneState		None
+#define XaceBackgroundNoneState(w) ((w)->forcedBG ? BackgroundPixel : None)
 
 /* security hooks */
 /* Constants used to identify the available security hooks
@@ -100,7 +100,7 @@ extern void XaceCensorImage(
 #else /* XACE */
 
 /* Default window background */
-#define XaceBackgroundNoneState		None
+#define XaceBackgroundNoneState(w)		None
 
 /* Define calls away when XACE is not being built. */
 
diff --git a/dix/window.c b/dix/window.c
index 70e32fbcf..9975b5eec 100644
--- a/dix/window.c
+++ b/dix/window.c
@@ -291,6 +291,7 @@ SetWindowToDefaults(WindowPtr pWin)
     pWin->dontPropagate = 0;
     pWin->forcedBS = FALSE;
     pWin->redirectDraw = RedirectDrawNone;
+    pWin->forcedBG = FALSE;
 }
 
 static void
@@ -702,8 +703,8 @@ CreateWindow(Window wid, WindowPtr pParent, int x, int y, unsigned w,
 	return NullWindow;
     }
 
-    pWin->backgroundState = XaceBackgroundNoneState;
-    pWin->background.pixel = 0;
+    pWin->backgroundState = XaceBackgroundNoneState(pWin);
+    pWin->background.pixel = pScreen->whitePixel;
 
     pWin->borderIsPixel = pParent->borderIsPixel;
     pWin->border = pParent->border;
@@ -1014,8 +1015,8 @@ ChangeWindowAttributes(WindowPtr pWin, Mask vmask, XID *vlist, ClientPtr client)
 		if (!pWin->parent)
 		    MakeRootTile(pWin);
 		else {
-		    pWin->backgroundState = XaceBackgroundNoneState;
-		    pWin->background.pixel = 0;
+		    pWin->backgroundState = XaceBackgroundNoneState(pWin);
+		    pWin->background.pixel = pScreen->whitePixel;
 		}
 	    }
 	    else if (pixID == ParentRelative)
diff --git a/include/windowstr.h b/include/windowstr.h
index a16132458..e06a2f1bd 100644
--- a/include/windowstr.h
+++ b/include/windowstr.h
@@ -159,6 +159,7 @@ typedef struct _Window {
     unsigned		dontPropagate:3;/* index into DontPropagateMasks */
     unsigned		forcedBS:1;	/* system-supplied backingStore */
     unsigned		redirectDraw:2;	/* COMPOSITE rendering redirect */
+    unsigned		forcedBG:1;	/* must have an opaque background */
 } WindowRec;
 
 /*