Received-SPF: pass (google.com: domain of selinux-refpolicy-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: Are we on the wrong track?
To:     Russell Coker <russell@coker.com.au>,
        selinux-refpolicy@vger.kernel.org
References: <3243717.6S2XvbbdUs@liv>
From:   Chris PeBenito <pebenito@ieee.org>
Message-ID: <578d7c7c-cb41-b224-2758-144aa9b5c1ad@ieee.org>
Date:   Fri, 12 Jun 2020 08:52:56 -0400
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.8.0
MIME-Version: 1.0
In-Reply-To: <3243717.6S2XvbbdUs@liv>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: selinux-refpolicy-owner@vger.kernel.org
Precedence: bulk

On 6/11/20 8:03 PM, Russell Coker wrote:
> The reference policy is getting an increasing number of domains and types with
> an O(N^2) level of complexity for writing policy and an O(N^2) size of the
> binary policy.  In 2012 the binary policy on my machines was 560k, now it's
> over 2M.
> 
> In recent policy we have 6 different domains for systemd-generators.  What
> benefit are we expecting to get from this?  Are we anticipating that one
> generator will attack another?  How would having separate domains for
> generators do any good when there's no restriction on the contents of the
> files they generate and nothing to prevent one generator from creating a file
> of the name that another generator is expected to create?  Is it even
> reasonable to expect that a program that can create a systemd unit file with
> arbitrary content (IE being able to start any daemon with arbitrary
> configuration and command-line parameters) would be unable to exploit that for
> unrestricted root access?

I find this a valid criticism and reason enough to at least collapse them into a 
single domain.  The original intent was to constrain the special access they 
use, but you are correct, a compromised generator could do mostly do all the bad 
things anyway since it can write unit files.

> We have a new set of domains, user_wm_t, staff_wm_t, etc.  What is that for?
> Is someone using the X controls and in need of a privileged window manager
> domain to manage the clipboard etc?

Yes.

>  Why is staff_wm_t needed when we no
> longer have staff_gpg_t?

Sounds like a gpg change that should be reverted.

>  Does staff_r even make sense when you could just use
> different MCS categories for different users?

Yes, as user_r cannot reach admin roles whereas staff_r can.

> We have one games_t domain for games which were packaged by the distribution.
> Is this possible to give a useful benefit given that they some games the same
> XDG config directories as more important things.  If a game has the file
> access needed to grab passwords from your MUA and network access to send them
> out then is there a real benefit in having a separate domain for it?  As an
> aside I think that the ideal thing to do would be to have a SETGID program to
> manage passwords for email etc that prevents the user from accessing them, it
> could then proxy IMAP/SMTP connections so the MUA never knows the real
> passwords.

I'm a bit hazy on the details you're referring to but you're right that games_t 
may not be too impactful. Dominick's flatpak/sandbox/container approach may make 
more sense.  I don't have any recent Linux gaming experience (with Steam or 
otherwise) to judge.

> We have special *_cronjob_t domains which in systems that use them (IE not
> Debian) seem to give the potential for nothing but confusion.  The general
> expectation is that anything which can run as a user login session can also
> run as a cron job.  What benefit is this expected to provide?

I'd be fine dropping the instantiaton of *_cronjob_t (except system_cronjob_t) 
but not removal of the template, for the few instances that users need it.

My question to you is why aren't you commenting on these changes as they are 
submitted, instead of unloading on the changes years after the fact?  You've 
been around the SELinux community longer than I have. These changes aren't 
merged in secrecy.

-- 
Chris PeBenito