Re: Emacs major mode for policy editing

[Bill Laut <wlsel@verizon.net>]

On Saturday 27 September 2003 11:43 pm, Russell Coker wrote:
> On Sun, 28 Sep 2003 06:24, Bill Laut wrote:
>
> > That's also why I threw in the reference to "extra homework" in my
> > previous post.  For example, this could be a good excuse to go through
> > XFree86 and insure that there aren't any unrecognized buffer-overflow
> > vulnerabilities. It would be embarassing to say the least to release
> > SE-X, only to have it contain exploitable BO vulnerabilities--the very
> > thing that SELinux is advertised as protecting against.
>
> Absolutely!  However it should be noted that SE Linux has a very expressive
> configuration language which allows detailed control over what is allowed.
> If an administrator desires Back-Orifice access to their network then the
> Security Enhanced X configuration will surely allow them to enable it.
>

This is to clarify the paragraph that you commented upon.  When I used the 
term "BO" I was abbreviating my earlier usage of "buffer-overflow."  I 
recognize that BO is the common abbreviation for "Back Orifice, and therefore 
I should have used a more discriminating abbreviation.  Therefore, in the 
future when I abbreviate "Buffer-Overflow" I will use "BuOv."  

I agree with what you said about an administrator -overtly- desiring to enable 
a Back Orifice; there's no way to prevent it, and in fact it's not our place 
to tell them they can't.  Given its size and complexity, what I'm pondering 
is the potential for as-yet undetected BuOv vulnerabilities in the existing 
XFree86 code.  Obviously, an appropriate policy will fence in a compromised 
Xserver, so long as it wasn't installed SUID.  eg, the Request passes policy 
enforcement, only to then be dispatched into a module with an unforeseen BuOv 
that allows a malicious Xclient to compromise the Xserver (or another Xclient 
with a BuOv in Xlib that was installed SUID).  That's why I was wondering if 
it would be appropriate to inspect XFree86 for boundary checking of all 
incoming client messages.

Bill


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