Re: AppArmor FAQ

Crispin Cowan
2007-04-18T19:41:41Z

James Morris wrote:
> On Tue, 17 Apr 2007, Alan Cox wrote:
>
>> I'm not sure if AppArmor can be made good security for the general case,
>> but it is a model that works in the limited http environment
>> (eg .htaccess) and is something people can play with and hack on and may
>> be possible to configure to be very secure.
>>
> Perhaps -- until your httpd is compromised via a buffer overflow or
> simply misbehaves due to a software or configuration flaw, then the
> assumptions being made about its use of pathnames and their security
> properties are out the window.
>
How is it that you think a buffer overflow in httpd could allow an
attacker to break out of an AppArmor profile? This is exactly what
AppArmor was designed to do, and without specifics, this is just FUD.

> Without security labeling of the objects being accessed, you can't protect
> against software flaws, which has been a pretty fundamental and widely
> understood requirement in general computing for at least a decade.
>
Please explain why labels are necessary for effective confinement. Many
systems besides AppArmor have used non-label schemes for effective
confinement: TRON, Janus, LIDS, Systrace, BSD Jail, EROS, PSOS, KeyOS,
AS400, to name just a few. This claim seems bogus. Labels may be your
method of choice for confinement, but they are far from the only way.

Crispin

--
Crispin Cowan, Ph.D. http://crispincowan.com/~crispin/
Director of Software Engineering http://novell.com