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Date: Mon, 8 Jun 2020 20:19:30 +0200
From: Mikhail Morfikov <mmorfikov@...il.com>
To: lkrg-users@...ts.openwall.com
Subject: Re: Outdated sysctl documentation

On 08/06/2020 17:18, Adam Zabrocki wrote:
> Hi,
> 
> We are on the edge of releasing a new LKRG version (0.8). However, we are still 
> working on some features which are changing some of the functinoality. Updating 
> documentation is the last step of the work which is in our TODO list.
> Current documentation refelct the last LKRG release (0.7).
> 
I see, OK no problem.

> Few weeks ago we've completely rewrote communication channel and documentation 
> for it is in the official commit:
> 
> https://bitbucket.org/Adam_pi3/lkrg-main/commits/2febcf467d6182e9bd180334e2601c79812f2cf5
> 
I have a couple of questions, which came to my mind while reading the commit:

-----------
 1) Introduce 'kint_validate' to control kernel/system integrity logic:
    0 - disabled
    1 - validation is performed only when manually triggered
    3 - validation is performed periodically by timer interrupt and on random events
-----------
1. By the "timer interrupt" you mean that if CONFIG_HZ=1000 then the check will 
   be performed 1000 times per second, am I right?
2. What do you mean by random events?
3. Is there a value of "2" or just "1" and "3"?

-----------
 2) Introduce 'kint_enforce' to control how LKRG reacts when kernel/system integrity fails:
    0 - log & accept corruption
    1 - log only (for SELinux and CR0.WP violation log & restore original values)
    2 - panic() - kill the kernel
-----------
4. What's actually the difference between "0" and "1"?

-----------
 6) Introduce 'smep_enforce' to control how LKRG reacts when SMEP validation fails:
    0 - log & accept
    1 - log & restore
    2 - panic() - kill the kernel
-----------
5. Is this similar to the previous one (I mean the value of "0" and "1")?

-----------
 8) Introduce 'smep_enforce' to control how LKRG reacts when UMH validation fails:
    0 - log only
    1 - prevent execution
    2 - panic() - kill the kernel
-----------
prevent execution... of?

-----------
 9) Introduce 'pcfi_validate' to control if pCFI validation will be performed
    0 - disabled
    1 - no stackwalk (weak pCFI)
    2 - fully enabled
-----------
What does "1" do here?
Does the CFI stand for Control-Flow Integrity?

-----------
 -> Hiding (lkrg.hide) - if built with this optional feature included, LKRG can
    (un)hide itself from the module list (but it can be detected regardless):
-----------
The doc says that hiding the module can be detected even when lkrg.hide=1 -- any 
example how to detect it in such situation?



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