Re: Preferred subj= with multiple LSMs

[Steve Grubb <sgrubb@redhat.com>]

Hello,

On Friday, July 12, 2019 12:33:55 PM EDT Casey Schaufler wrote:
> Which of these options would be preferred for audit records
> when there are multiple active security modules?

I'd like to start out with what is the underlying problem that results in 
this? For example, we have pam. It has multiple modules each having a vote. 
If a module votes no, then we need to know who voted no and maybe why. We 
normally do not need to know who voted yes.

So, in a stacked situation, shouldn't each module make its own event, if 
required, just like pam? And then log the attributes as it knows them? Also, 
what model is being used? Does first module voting no end access voting? Or 
does each module get a vote even if one has already said no?

Also, we try to keep LSM subsystems separated by record type numbers. So, 
apparmour and selinux events are entirely different record numbers and 
formats. Combining everything into one record is going to be problematic for 
reporting.

-Steve

> I'm not asking
> if we should do it, I'm asking which of these options I should
> implement when I do do it. I've prototyped #1 and #2. #4 is a
> minor variant of #1 that is either better for compatibility or
> worse, depending on how you want to look at it. I understand
> that each of these offer challenges. If I've missed something
> obvious, I'd be delighted to consider #5.
> 
> Thank you.
> 
> Option 1:
> 
> 	subj=selinux='x:y:z:s:c',apparmor='a'
> 
> Option 2:
> 
> 	subj=x:y:z:s:c subj=a
> 
> Option 3:
> 
> 	lsms=selinux,apparmor subj=x:y:z:s:c subj=a
> 
> Option 4:
> 
> 	subjs=selinux='x:y:z:s:c',apparmor='a'
> 
> Option 5:
> 
> 	Something else.