Re: [gentoo-hardened] New Server, considering hardened, need pointers to tfm...

[Kevin Chadwick]

On Tue, 13 Dec 2011 22:20:00 +0100
Javier Juan Martínez Cabezón wrote:

> Give me an example of direct attack via memory as you say, accessible
> devices and anything else said you before.

I suggest you do some more reading at grsecurity.net or even the
OpenBSD mailing list. I haven't got time to hunt down the two references
that stick in my mind but keep your ears open and you may realise one
of the kernel exploits could/can/will do just that. Do you really
believe it's impossible??!!


>> Shall we get rid of file permissions because we have RBAC. We could
>> but I can't see that happening and for good reason.

> file permissions are discrectional, rbac mostly mandatory

I have no idea what you are arguing with, you just keep trying to twist
what I say because you have a bee in your bonnet about MACs as the
answer to everything and a panacea, they aren't but they are useful as I
have said. Personally I wouldn't swap an OpenBSD kernel for the Linux
one with RBAC on my servers atleast. One day with a risky setup, I
might in that instance. I wonder why kernel.org didn't use RBACs,
especially RSBAC or even chroot. How embarrassing for such an automated
attack to get through. Is bugzilla.kernel.org still down? That wouldn't
have happened if they were using OpenBSD. It might be a good idea to use
a different kernel to the one they are hosting anyway even with many
eyes. And before you think well this is just me clutching at straws with
your tunnel vision, it relates exactly to what I was talking about
of likelihood of use.

>> don't try to compare them.

Of course you should and I was saying much of RBACs can be replaced and
you use both and it adds to defence in depth. Your notion of replacing
DACs? I see good and bad in that.


>> It does not restrict root, it erase it. The concept of root doesn't
>> exists anymore.

What is root, it is the root of the system not just a user. If it
didn't exist the kernel wouldn't be able to turn RBAC off now would it.
You have been drawn in by the wonderful marketing of imagine a system
where root doesn't exist. Would your analogy be the kernel recreates
root. If so, fine it makes no difference but is less correct.


> I use rsbac because it reachs to B1 security level, level that openbsd
> will never reach, it supports even secure_delete, and has some B2
> charateristics as device labels are.


And yet your kernel has bugs added every day without much security
consideration. What you don't understand is that RBAC is a security
layer that the root of the system has control of. What can
your /sbin/init do, what can the kernel do? Some rootkits can actually
go the other side of the kernel even, far above where RBACs are.

Yeah and Cisco's are certified for use by some enterprise manager and
yet they have proven full of root exploits. Certified encryptions are
often less secure than others.

I repeat it ALL depends on the application, even the hardware. You
could reduce the Linux kernel right down to protect the RBAC. Which
was my original point.

Of course then I wonder if the RBAC would actually ever be needed but
it's ALL GOOD.