From ed64eecac193e7579f604e04f0aec7bb21b07f98 Mon Sep 17 00:00:00 2001
From: dtucker <dtucker>
Date: Wed, 15 Aug 2007 09:13:41 +0000
Subject: [PATCH]    - markus@cvs.openbsd.org 2007/08/15 08:14:46     
 [clientloop.c]      do NOT fall back to the trused x11 cookie if generation
 of an untrusted      cookie fails; from security-alert at sun.com; ok dtucker

---
 ChangeLog    |  7 +++++++
 clientloop.c | 38 ++++++++++++++++++++++++--------------
 2 files changed, 31 insertions(+), 14 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index a99a6af2..eee33e36 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+20070815
+ - (dtucker) OpenBSD CVS Sync
+   - markus@cvs.openbsd.org 2007/08/15 08:14:46
+     [clientloop.c]
+     do NOT fall back to the trused x11 cookie if generation of an untrusted
+     cookie fails; from security-alert at sun.com; ok dtucker
+
 20070813
  - (dtucker) [session.c] Bug #1339: ensure that pam_setcred() is always
    called with PAM_ESTABLISH_CRED at least once, which resolves a problem
diff --git a/clientloop.c b/clientloop.c
index 538644c2..b57fda04 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.180 2007/08/07 07:32:53 djm Exp $ */
+/* $OpenBSD: clientloop.c,v 1.181 2007/08/15 08:14:46 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -290,19 +290,29 @@ client_x11_get_proto(const char *display, const char *xauth_path,
 					generated = 1;
 			}
 		}
-		snprintf(cmd, sizeof(cmd),
-		    "%s %s%s list %s 2>" _PATH_DEVNULL,
-		    xauth_path,
-		    generated ? "-f " : "" ,
-		    generated ? xauthfile : "",
-		    display);
-		debug2("x11_get_proto: %s", cmd);
-		f = popen(cmd, "r");
-		if (f && fgets(line, sizeof(line), f) &&
-		    sscanf(line, "%*s %511s %511s", proto, data) == 2)
-			got_data = 1;
-		if (f)
-			pclose(f);
+
+		/*
+		 * When in untrusted mode, we read the cookie only if it was
+		 * successfully generated as an untrusted one in the step
+		 * above.
+		 */
+		if (trusted || generated) {
+			snprintf(cmd, sizeof(cmd),
+			    "%s %s%s list %s 2>" _PATH_DEVNULL,
+			    xauth_path,
+			    generated ? "-f " : "" ,
+			    generated ? xauthfile : "",
+			    display);
+			debug2("x11_get_proto: %s", cmd);
+			f = popen(cmd, "r");
+			if (f && fgets(line, sizeof(line), f) &&
+			    sscanf(line, "%*s %511s %511s", proto, data) == 2)
+				got_data = 1;
+			if (f)
+				pclose(f);
+		} else
+			error("Warning: untrusted X11 forwarding setup failed: "
+			    "xauth key data not generated");
 	}
 
 	if (do_unlink) {
-- 
2.45.2