What are these for?

[Alan Cox]

> > Because the syslog interface isn't secure. 
> 
> How come?  Only root can read the logfile.

The logging interface is not secure, it provides a generic path for
anyone to log stuff.

> Well I can't predict the future.  What does mcelog actually do to
> prevent hardware problems or to make the system respond to them properly
> --- whatever "properly" means?

It decoders the CPU state dumped by the exception from the kernel in a
human understandable form.

> >> Regular users must not change the system time.  It's on UTC and kept on
> >> track with chrony.
> >
> > Well, exactly. That's why you would need extra authentication to change it.
> 
> Users are not supposed to change it at all, not even with extra
> authentication.

A user with extra authentication to be gain root is no different to su

> > It wouldn't. In a GUI, polkit has a distinctive, separate dialog box it uses
> > to ask for authentication. It's absolutely true that spoofing this sort of
> > dialog is a concern.
> 
> So yes, it decreases security instead of increasing it.

No different. I can equally spoof you a shell window.

> What difference does it make which password is supplied when with the
> password things can be done that are relevant for security?  Why should
> I give my password again when I'm already logged in and the system knows
> who I am?

Configure the policy how you like.

> And what if the user in the wheel group wants to use emacs to edit some
> configuration file that can only be modified by root?

They can use su if they want to use emacs for it.

Alan