RE: 'sign' modules? was: RE: 'lock' modules?

From: ronbarry@es.com
Date: Wed Jun 07 2000 - 02:59:05 EST


I had suspected that this had come up before. However, the suggestion is
still valid. This is not an attempt to keep an intruder from loading
something whatever they like. It is an attempt to keep a careless,
legitimate root from loading something that would be harmful.

So, 1) the intruder at this point has no access, and 2) can therefore not
introduce a 'butchered' insmod.

To recap, this is NOT an attempt to restrict an intruder (no shit, root can
do whatever he likes) just to give a friendly "are you _really_ sure you
know what you are doing?" to the legitimate owner of the machine, lest he
install a trojan or other nasty.

        rOn

> -----Original Message-----
> From: Keith Owens [mailto:kaos@ocs.com.au]
> Sent: Wednesday, June 07, 2000 1:31 AM
> To: ronbarry@es.com
> Cc: linux-kernel@vger.rutgers.edu
> Subject: Re: 'sign' modules? was: RE: 'lock' modules?
>
>
> On Wed, 7 Jun 2000 01:04:12 -0600 ,
> ronbarry@es.com wrote:
> >Anyway, what if we were to institute a system where a kernel
> module could be
> >digitally signed by assorted authorities as 'blessed?'
>
> Sigh. Why do people keep bring up this topic without reading the
> archives first? This has been discussed and rejected before but one
> more time ....
>
> Module loading is handled by user space utilities, not the kernel. To
> bypass signed modules a hacker can use their own user space code,
> either a butchered version of insmod or they just invoke the module
> syscalls directly from their own programs.
>
> Once more with feeling - "root can do anything that root is allowed to
> do". First design a mechanism to distinguish between a good and a bad
> root user, when you have working code send it to the list.
>

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