Subject: Use initgroups() to initialize group access list
From: Orion Poplawski <[email-masked]>
To: [email-masked]
Date: Thu, 29 Aug 2013 11:12:14 -0600

Package: nx-libs
Tags: patch

The Fedora review of nx-libs caught the following rpmlint issue:

This executable is calling setuid and setgid without setgroups or initgroups.
There is a high probability this mean it didn't relinquish all groups, and this
would be a potential security issue to be fixed. Seek POS36-C on the web for
details about the problem.

Ref POS36-C:

https://www.securecoding.cert.org/confluence/display/seccode/POS36-C.+Observe+correct+revocation+order+while+relinquishing+privileges 

This patch adds initgroups() calls to code to initialize the supplemental 
group list.

I'm done some minimal testing (can connect to a session with client and server 
running this code), but I'm note sure how much that exercised it.

-- 
Orion Poplawski
Technical Manager                     303-415-9701 x222
NWRA, Boulder/CoRA Office             FAX: 303-415-9702
3380 Mitchell Lane                       [email-masked]
Boulder, CO 80301                   http://www.nwra.com
diff --git a/nx-X11/programs/Xserver/os/utils.c b/nx-X11/programs/Xserver/os/utils.c
index 7e62654..9b2431a 100644
--- a/nx-X11/programs/Xserver/os/utils.c
+++ b/nx-X11/programs/Xserver/os/utils.c
@@ -112,6 +112,9 @@ OR PERFORMANCE OF THIS SOFTWARE.
 #include <sys/stat.h>
 #include <ctype.h>    /* for isspace */
 #include <stdarg.h>
+#include <sys/types.h>
+#include <grp.h>
+#include <pwd.h>
 
 #if defined(DGUX)
 #include <sys/resource.h>
@@ -1770,6 +1773,7 @@ System(char *command)
     void (*csig)(int);
 #endif
     int status;
+    struct passwd *pwent;
 
     if (!command)
 	return(1);
@@ -1791,6 +1795,9 @@ System(char *command)
     case -1:	/* error */
 	p = -1;
     case 0:	/* child */
+	pwent = getpwuid(getuid());
+	if (initgroups(pwent->pw_name,getgid()) == -1)
+	    _exit(127);
 	if (setgid(getgid()) == -1)
 	    _exit(127);
 	if (setuid(getuid()) == -1)
diff --git a/nxcomp/Pipe.cpp b/nxcomp/Pipe.cpp
index 7238d0c..aacbbae 100644
--- a/nxcomp/Pipe.cpp
+++ b/nxcomp/Pipe.cpp
@@ -21,6 +21,7 @@
 #include <pwd.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <grp.h>
 
 #include "Pipe.h"
 #include "Misc.h"
@@ -234,6 +235,8 @@ FILE *Popen(char * const parameters[], const char *type)
       // Child.
       //
 
+      struct passwd *pwent = getpwuid(getuid());
+      if (pwent) initgroups(pwent->pw_name,getgid());
       setgid(getgid());
       setuid(getuid());