Re: [PATCH] Version 3 (2.6.23-rc8) Smack: Simplified Mandatory Access Control Kernel

Serge E. Hallyn
2007-10-08T18:53:19Z

Quoting Eric W. Biederman (ebiederm@xmission.com):
> Casey Schaufler <casey@schaufler-ca.com> writes:
>
> > --- "Eric W. Biederman" <ebiederm@xmission.com> wrote:
> >
> >
> >> Likely. Until we have a generalized LSM interface with 1000 config
> >> options like netfilter I don't expect we will have grounds to talk
> >> or agree to a common user space interface. Although I could be
> >> wrong.
> >
> > Gulp. I know that many of you are granularity advocates, but I
> > have to say that security derived by tweeking 1000 knobs so that
> > they are all just right seems a little far fetched to me. I see
> > it as poopooing the 3rd and most important part of the reference
> > monitor concept, "small enough to analyze". Sure, you can analyse
> > the 1000 individual checks, but you'll never be able to describe
> > the system behavior as a whole.
>
> Agreed. I wasn't thinking 1000 individual checks but 1000 different
> capabilities, could be either checks or actions, basically fundamental
> different capabilities. Things like CIPSO, or the ability to store a
> security label on a file. I would not expect most security policies
> to use most of them. Neither do I expect Orange book security to
> necessarily be what people want to achieve with the LSM. But I
> haven't looked at it enough detail to know how things should be
> factored, in this case I was simply extrapolating from the iptables
> experience where we do have a very large number of options.
>
> The real point being is that I would be surprised if we could come
> to an agreement of a common user space API when we can't agree on how
> to compile all of the security modules into the kernel and have them
> play nice with each other.
>
> Assuming we can achieve security modules playing nice with each other
> using a mechanism similar to iptables, then what needs to be evaluated
> is the specific table configuration we are using on the system, not
> the full general set of possibilities. Further I expect that for the
> truly security paranoid we want the option to disable further table
> changes after the tables have been configured.
>
> On another side personally I don't see where the idea comes from that
> you can describe system behavior as a whole without analyzing the
> entire kernel. Has there been work on a sparse like tool that I'm
> not aware of to ensure the we always perform the appropriate security
> checks on the user/kernel interface boundary?

Yup, see the top of http://www.research.ibm.com/vali/

Pretty cool work that really should be continued.

-serge