Re: Question about /dev/mem and /dev/kmem

[Jim Nelson <james4765@verizon.net>]

Wichert Akkerman wrote:
> Previously Jim Nelson wrote:
> 
>>I was looking at some articles about rootkits on monolithic kernels, and 
>>had a thought.  Would a kernel config option to disable write access to 
>>/dev/mem and /dev/kmem be a workable idea?
> 
> 
> Yes, but not a very useful one since it is an incomplete solution. You
> can easily do something better using /proc/kernel/cap-bound

Isn't that /proc/sys/kernel/cap-bound?

> (like writing 0xFFFCFFFF into it).
> 

And what stops an attacker who's already gained root from doing a "cat "0" > 
/proc/sys/kernel/cap-bound" ?

> Wichert.
>