selinux: Support for the new TUN LSM hooks

Add support for the new TUN LSM hooks: security_tun_dev_create(),
security_tun_dev_post_create() and security_tun_dev_attach().  This includes
the addition of a new object class, tun_socket, which represents the socks
associated with TUN devices.  The _tun_dev_create() and _tun_dev_post_create()
hooks are fairly similar to the standard socket functions but _tun_dev_attach()
is a bit special.  The _tun_dev_attach() is unique because it involves a
domain attaching to an existing TUN device and its associated tun_socket
object, an operation which does not exist with standard sockets and most
closely resembles a relabel operation.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: Eric Paris <eparis@parisplace.org>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/selinux/include/flask.h b/security/selinux/include/flask.h
index 882f27d..f248500 100644
--- a/security/selinux/include/flask.h
+++ b/security/selinux/include/flask.h
@@ -53,6 +53,7 @@
 #define SECCLASS_PEER                                    68
 #define SECCLASS_CAPABILITY2                             69
 #define SECCLASS_KERNEL_SERVICE                          74
+#define SECCLASS_TUN_SOCKET                              75
 
 /*
  * Security identifier indices for initial entities