Subject: Re: [PATCH 2/3] Security: Implement disablenetwork semantics. (v4)

From: Michael Stone <[email-masked]>
Date: Sun, 10 Jan 2010 17:40:10 -0500

Pavel Machek wrote:

> You can trivialy make disablenetwork disable setuid exec, too. That
> will introduce better isolation facilities, but not introduce any new
> security problems.
> 
> For some reason, you don't want to do the obviously right thing.

I don't want to do it because it's not "obviously right" to me: I *have* setuid
programs that I want to be able to raise privileges when network-disabled.
I *don't have* any setuid programs that will be harmed by disablenetwork.

Examples of software that I want to be able to gain privileges normally include:

   rainbow, which requires privilege in order to add new accounts to the system
   and in order to call setuid() but which does not require networking
   privileges.

   qmail-queue, which uses setuid to deliver mail that it reads from fd 0 to
   local users

   and other old favorites like mount, fusermount, X, and, presumably, any audio
   software that wants to go realtime.

Kind regards,

Michael