Rational model for UID based controls

From: David Howells
Date: Wed Jun 05 2019 - 13:01:05 EST

Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote:

> YES!

I'm trying to decide if that's fervour or irritation at this point ;-)

> And it would be really great if you put some thought into what
> a rational model would be for UID based controls, too.

I have put some thought into it, but I don't see a single rational model. It
depends very much on the situation.

In any case, that's what I was referring to when I said I might need to call
inode_permission(). But UIDs don't exist for all filesystems, for example,
and there are no UIDs on superblocks, mount objects or hardware events.

Now, I could see that you ignore UIDs on things like keys and
hardware-triggered events, but how does this interact with things like mount
watches that see directories that have UIDs?

Are you advocating making it such that process B can only see events triggered
by process A if they have the same UID, for example?