SELinux: Socket retains creator role and MLS attribute

The socket SID would be computed on creation and no longer inherit
its creator's SID by default. Socket may have a different type but
needs to retain the creator's role and MLS attribute in order not
to break labeled networking and network access control.

The kernel value for a class would be used to determine if the class
if one of socket classes. If security_compute_sid is called from
userspace the policy value for a class would be mapped to the relevant
kernel value first.

Signed-off-by: Harry Ciao <qingtao.cao@windriver.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>

security/selinux/ss/mls.h

@@ -49,7 +49,8 @@ int mls_compute_sid(struct context *scontext,
 		    struct context *tcontext,
 		    u16 tclass,
 		    u32 specified,
-		    struct context *newcontext);
+		    struct context *newcontext,
+		    bool sock);
 
 int mls_setup_user_range(struct context *fromcon, struct user_datum *user,
 			 struct context *usercon);