netdev - Re: [RFC Patch] net: reserve ports for applications using fixed port numbers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 5 Feb 2010 03:05:22 +0200
From:	Octavian Purdila <opurdila@...acom.com>
To:	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:	davem@...emloft.net, amwang@...hat.com,
	linux-kernel@...r.kernel.org, eric.dumazet@...il.com,
	linux-rdma@...r.kernel.org, netdev@...r.kernel.org,
	nhorman@...driver.com, linux-sctp@...r.kernel.org
Subject: Re: [RFC Patch] net: reserve ports for applications using fixed port numbers

On Friday 05 February 2010 02:41:12 you wrote:
> David Miller wrote:
> > > Octavian Purdila wrote:
> > >> int inet_is_reserved_local_port(int port)
> > >> {
> > >> 	if (test_bit(port, reserved_ports))
> > >> 		return 1;
> > >> 	return 0;
> > >> }
> > >
> > > Above check is exactly what I'm doing in the LSM hook.
> >
> > But his version can be done inline in 2 or 3 instructions.
> >
> > An LSM hook will result in an indirect function call,
> > all live registers spilled to the stack, then all of
> > those reloaded when the function returns.
> >
> > It will be much more expensive.
> 
> If you can accept his version, I want to use his version (with an interface
>  for updating above "reserved_ports" by not only root user's sysctl() but
>  also MAC's policy configuration).
> 

I think that simply using an interface to update the reserved_ports from MAC 
policy configuration module wouldn't work, as root will be able to modify the 
policy via sysctl.

I think that we might need to:

a) have a reserved_port updater

b) put a LSM hook into that

c) use the reserved_port updater from sysctl



--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html