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Date:      Sat, 30 Sep 2000 18:37:14 -0400
From:      "Brian F. Feldman" <green@FreeBSD.org>
To:        cjclark@alum.mit.edu
Cc:        security@FreeBSD.org
Subject:   Re: cvs commit: ports/mail/pine4 Makefile (fwd) 
Message-ID:  <200009302237.e8UMbE544527@green.dyndns.org>
In-Reply-To: Message from "Crist J . Clark" <cjclark@reflexnet.net>  of "Sat, 30 Sep 2000 15:14:36 PDT." <20000930151436.D25121@149.211.6.64.reflexcom.com> 

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"Crist J . Clark" <cjclark@reflexnet.net> wrote:
> On Sat, Sep 30, 2000 at 04:22:46PM -0500, Mike Silbersack wrote:
> > 
> > On Sat, 30 Sep 2000, Brian F. Feldman wrote:
> > 
> > > That is, one can create their own jail (or just chroot(8)... I should 
> > > probably get user-chrooting reviewed ;) which they would use for running 
> > > potentially evil things -- like reading e-mail with pine.  It's not too 
> > > difficult, but it's really easier just to switch to a better MUA.
> > 
> > user-chrooting would be excellent.  Chrooting MUAs / web browsers / etc
> > would be a nice feature no matter how secure the program in question seems
> > to be.  If you get it implemented, I'll be the first to use the
> > feature. :)
> 
> Why not just run each program under a different user? From the
> multi-user heritage of the OS, it is really good at keeping users from
> messing with each other's stuff. You set up a user to read mail, a
> user to browse, and a user to do whatever else is "risky." You can
> have one not-too-super-super-user (that you never do anything to risky
> with) who can access stuff from all of these individual users via
> group permissions. Here is an example, you have groups,
> 
>   mymailer:*:2010:mysu
>   mysurfer:*:2020:mysu
>   mygamer:*:2030:mysu
> 
> And each of those users has a 002 umask. From you mysu account you can
> access everything. From mymailer, you can only screw up your mail
> (something that chrooting would not get around either).
> 
> This might be an admin nightmare for systems that _are_ being used for
> true multi-user (more than one real person) systems. But for the
> average home box or single-user desktop, this seems that it does all
> chroot would do and then some with no extra hassles.
> -- 
> Crist J. Clark                           cjclark@alum.mit.edu

I was going to suggest this, where a compromise would result in a 
_different_ user losing all its stuff (you mail only?), but it would still 
allow remote users to mount local attacks against suid programs and such.  
In a chroot, the only attacks would be ptrace()-based or socket()-based...  
In a jail, you have maybe sysv*-based attacks.


--
 Brian Fundakowski Feldman           \  FreeBSD: The Power to Serve!  /
 green@FreeBSD.org                    `------------------------------'




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