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

From: [email-masked]
Date: Mon, 18 Jan 2010 07:54:04 -0500

On Thu, 14 Jan 2010 10:22:51 +0100, Pavel Machek said:
> > On Tue, 12 Jan 2010 08:59:27 +0100, Pavel Machek said:
> > 
> > > Well, maybe, but mailer system where first user starts is as a daemon
> > > makes sense...
> > 
> > Does it?  How do you get port 25 open for listening if the first user isn't
> > root?  Most *actual* schemes to "launch at first use" that require privs fo
r
> > something have used inetd or similar - that program exists for a
> > *reason*.
> 
> Remember sendmail is setuid root... so it already has the permissions.

Actually, the sendmail setuid bit was removed quite some time ago:

8.12.0/8.12.0   2001/09/08
        *NOTICE*: The default installation of sendmail does not use
                set-user-ID root anymore.  You need to create a new user and
                a new group before installing sendmail (both called smmsp by
                default).  The installation process tries to install
                /etc/mail/submit.cf and creates /var/spool/clientmqueue by
                default.  Please see sendmail/SECURITY for details.

Wow.  2001. And people *still* think it's setuid. ;)

(Interestingly enough, the capabilities bug came *later*:

8.12.1/8.12.1   2001/10/01
        SECURITY: Check whether dropping group privileges actually succeeded
                to avoid possible compromises of the mail system by
                supplying bogus data.  Add configuration options for
                different set*gid() calls to reset saved gid.  Problem
                found by Michal Zalewski.

and was mostly an issue because the same problem existed in pre-8.12 sendmails
that were still setuid and hadn't upgraded yet...