SELinux module to allow a single network port?

[Stephen Smalley]

On Fri, 2008-02-15 at 11:03 -0600, Chris Adams wrote:
> I originally posted this to the RHEL5 list, but someone pointed me to
> this list (I didn't realize there was an SELinux list).
> 
> I have done some minor SELinux customizations with a module, and now I'm
> trying to do something a little more complicated.
> 
> I want to allow a CGI to do a "whois" lookup.  It is a perl script that
> is attempting to open a TCP socket to port 43.  I ran audit2allow, but I
> think the generated rule allows CGIs to open outbound sockets to any
> port.  I'd rather just allow TCP to port 43.
> 
> I don't see a defined whois port type, and I don't know quite how to
> define it myself in a module.
> 
> Help?

Possibly something like this:

$ vi whois.te
policy_module(whois, 1.0)
type whois_port_t, port_type;
:wq
$ make -f /usr/share/selinux/devel/Makefile whois.pp
$ su
# semodule -i whois.pp
# semanage port -a -t whois_port_t -p tcp 43

-- 
Stephen Smalley
National Security Agency