Re: [PATCH 0/6] MODSIGN: Kernel module signing

Dave Jones
2007-02-16T20:22:01Z

On Thu, Feb 15, 2007 at 10:13:04PM +0000, Pavel Machek wrote:
> Hi!
>
> > Now, this is not a complete solution by any means: the core kernel is not
> > protected, and nor are /dev/mem or /dev/kmem, but it denies (or at least
> > controls) one relatively simple attack vector.
>
> Could we fix the /dev/*mem holes, first? They are already used by
> malicious modules (aka rootkits...). Or can selinux already provide
> /dev/*mem protection with no way for admin to turn it off?

There are some valid uses for peeking through /dev/mem. Things like
dmidecode for example. So you don't want to disable it completely
in a lot of cases, but have fine-grained access to specific parts
of the file. I'm not sure SELinux can do this. Maybe the MLS stuff
helps here (though I'm far from an expert on this, so I could be
talking out of my rear).

The restricted dev/mem patches we've had in Fedora for a while
do the right thing, but they're a bit crufty (in part due to
drivers/char/mem.c being a bit of a mess before we even start
patching it). I've had "clean these up for upstream" on my
todo for a while. I might get around to it one of these days.

Dave

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