trouble shutting down avc netlink socket

[Stephen Smalley]

On Mon, 2004-08-23 at 15:37, Colin Walters wrote:
> Hi,
> 
> I'm having a problem where calling avc_destroy doesn't seem to close the
> netlink socket, because a subsequent avc_init is unable to bind to the
> socket, and gets an error "Address already in use".
> 
> The attached test program lets me reproduce the problem - the very
> interesting thing is it seems to only happen about 50% of the time.  Is
> there some race here in the kernel?
> 
> As far as I can tell the close() is being called so the socket should be
> shut down.

Changing libselinux to not set the pid in the socket address (so that
the kernel auto-binds the socket) seems to avoid the problem, but this
may just be covering the underlying bug.

Index: libselinux/src/avc_internal.c
===================================================================
RCS file: /nfshome/pal/CVS/selinux-usr/libselinux/src/avc_internal.c,v
retrieving revision 1.14
diff -u -r1.14 avc_internal.c
--- libselinux/src/avc_internal.c	15 Jun 2004 18:47:10 -0000	1.14
+++ libselinux/src/avc_internal.c	23 Aug 2004 20:11:31 -0000
@@ -69,7 +69,6 @@
 	
   memset(&addr, 0, len);
   addr.nl_family = AF_NETLINK;
-  addr.nl_pid = getpid();
   addr.nl_groups = SELNL_GRP_AVC;
 	
   if (bind(fd, (struct sockaddr *)&addr, len) < 0) {
 
-- 
Stephen Smalley <sds at epoch.ncsc.mil>
National Security Agency