Subject: Re: [PATCH 3/5] v2 seccomp_filters: Enable ftrace-based system call filtering

From: Ingo Molnar <[email-masked]>
Date: Tue, 17 May 2011 15:10:58 +0200

* James Morris <[email-masked]> wrote:

> On Mon, 16 May 2011, Ingo Molnar wrote:
> 
> > > Not really.
> > > 
> > > Firstly, what is the security goal of these restrictions? [...]
> > 
> > To do what i described above? Namely:
> > 
> >  " Sandboxed code should only be allowed to open files in /home/sandbox/, /lib/
> >    and /usr/lib/ "
> 
> These are access rules, they don't really describe a high-level security 
> goal. [...]

Restrictng sandboxed code to only open files within a given VFS namespace 
boundary sure sounds like a high-level security goal to me.

If implemented and set up correctly then it restricts sandboxed code to only be 
able to open files reachable via that VFS sub-namespace.

That is a rather meaningful high-level concept. What higher level concept do 
you want to argue?

> [...]  How do you know it's ok to open everything in these directories?

How do you know it's ok to open /etc/hosts? The sysadmin has configured the 
system that way.

How do you know that it's ok for sandboxed code to open files in 
/home/sandbox/? The sandbox developer has configured the system that way.

I'm not sure i get your point.

Thanks,

	Ingo