selinux: add type_transition with name extension support for selinuxfs

The attached patch allows /selinux/create takes optional 4th argument
to support TYPE_TRANSITION with name extension for userspace object
managers.
If 4th argument is not supplied, it shall perform as existing kernel.
In fact, the regression test of SE-PostgreSQL works well on the patched
kernel.

Thanks,

Signed-off-by: KaiGai Kohei <kohei.kaigai@eu.nec.com>
[manually verify fuzz was not an issue, and it wasn't: eparis]
Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index bfc5218..2cf6708 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -112,8 +112,8 @@
 int security_transition_sid(u32 ssid, u32 tsid, u16 tclass,
 			    const struct qstr *qstr, u32 *out_sid);
 
-int security_transition_sid_user(u32 ssid, u32 tsid,
-				 u16 tclass, u32 *out_sid);
+int security_transition_sid_user(u32 ssid, u32 tsid, u16 tclass,
+				 const char *objname, u32 *out_sid);
 
 int security_member_sid(u32 ssid, u32 tsid,
 	u16 tclass, u32 *out_sid);