Re: HW access allowed ?

Raul Miller (rdm@test.legislate.com)
Wed, 8 Apr 1998 21:20:04 -0400


Richard B. Johnson <root@chaos.analogic.com> wrote:
> Now Linux is Unix. There is now an ongoing program to provide Unixes
> (including Linux) with a privilege bit-map such as VAX/VMS. This will
> allow more controlled access to shared resources than the current
> "superuser can do anything", mode. However, there must be a privilege
> to set the privilege bits, you give this to a user or a privileged
> program and you are back to the "superuser can do anything" mode.

But, since this is a rarely used priviledge, you can audit its use,
if it really matters to you. [For example, configure the system so
that the program which changes priviledges refuses to do anything
until the dongle on the parallel port is properly seated, and the
logging host has responsed with a properly signed response to the
notification message.]

On the other hand, note that such security measures are not without
their own risks. Fundamentally, each priviledge has its own set of
risks, and even if an exploit doesn't give an attacker complete control
of the system a partitioned priviledge set opens up a whole new set of
exploits. [For example, given a certain level of access, you might be
able to arrange that any attempt at logging fails with a hard error...
Or consider the effect of raw socket access by a non-root user in a
supposedly secure lan environment.]

-- 
Raul

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