Quoting Jean-Marc Pigeon (j...@safe.ca):
> Hello,
> 
> 
> > 
> > I was wondering out loud about the best design to solve his problem.
> > 
> > If we try to redirect kernel-generated messages to containers, we have
> > several problems, including whether we need to duplicate the messages
> > to the host container.  So in one sense it seems more flexible to
> >     1. send everything to host syslog
>               No, if we do that all CONTs message will reach
>               the same bucket and it will be difficult to sort
>               them out..
>               CONT sys_admin and HOST sys_admin could be different
>               "entity", so you debug CONT config and critical
>               needed information reach HOST (which you do not 
>               have access to).

Yes, so a privileged task on HOST must pass that information back to
you on CONT.  That is not a valid complaint imo.  But how to sort the
msgs out is a valid question.

We need some sort of identifier, unique system-wide, attached to.. something.
Is ifindex unique system-wide right now?  Oh, IIRC it is, but we wnat it to
be containerized, so that would be a bad choice :)

> >     2. clamp down on syslog use by processes not in the init_user_ns
>               Could give me more detail??...

Simplest choices would be to just refuse sys_syslog() and open(/proc/kmsg)
altogether from a container, or to only allow reading/writing messages
to own syslog.  (I had hoped to find time to try out the second option but
simply haven't had the time, and it doesn't look like I will very soon.
So if anyone else wants to, pls jump at it...)

Then /proc/kmsg can provide what I described above through a FUSE file,
and if, as you mentioned, the container unmounts the FUSE fs and gets
to real procfs, they just get nothing.

> >     3. let the userspace on the host copy messages into a socket or
> >        file so child container can pretend it has real syslog.
> 
>               So you trap printk message from CONT on the HOST and 
>               redirect them on CONT but on a standard syslog channel.
>               Seem OK to me, as long /proc/kmsg is not existing
>               (/dev/null) in the CONT file tree.
>               
> -- 
> A bientôt
> ==========================================================================
> Jean-Marc Pigeon                                   Internet: j...@safe.ca
> SAFE Inc.                                          Phone: (514) 493-4280
>                                                    Fax:   (514) 493-1946
>         Clement, 'a kiss solution' to get rid of SPAM (at last)
>            Clement' Home base <"http://www.clement.safe.ca";>
> ==========================================================================

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