Re: [PATCH 0/2] namespaces: log namespaces per task

[Richard Guy Briggs]

On 14/05/05, Serge E. Hallyn wrote:
> Quoting James Bottomley (James.Bottomley@xxxxxxxxxxxxxxxxxxxxx):
> > On Tue, 2014-04-22 at 14:12 -0400, Richard Guy Briggs wrote:
> > > Questions:
> > > Is there a way to link serial numbers of namespaces involved in migration of a
> > > container to another kernel?  (I had a brief look at CRIU.)  Is there a unique
> > > identifier for each running instance of a kernel?  Or at least some identifier
> > > within the container migration realm?
> > 
> > Are you asking for a way of distinguishing an migrated container from an
> > unmigrated one?  The answer is pretty much "no" because the job of
> > migration is to restore to the same state as much as possible.
> > 
> > Reading between the lines, I think your goal is to correlate audit
> > information across a container migration, right?  Ideally the management
> > system should be able to cough up an audit trail for a container
> > wherever it's running and however many times it's been migrated?
> > 
> > In that case, I think your idea of a numeric serial number in a dense
> > range is wrong.  Because the range is dense you're obviously never going
> > to be able to use the same serial number across a migration.  However,
> 
> Ah, but I was being silly before, we can actually address this pretty
> simply.  If we just (for instance) add
> /proc/self/ns/{ic,mnt,net,pid,user,uts}_seq containing the serial number
> for the relevant ns for the task, then criu can dump this info at
> checkpoint.  Then at restart it can dump an audit message per task and
> ns saying old_serial=%x,new_serial=%x.  That way the audit log reader
> can if it cares keep track.

This is the sort of idea I had in mind...

> -serge
> 
> (Another, more heavyweight approach would be to track all ns hierarchies
> and make the serial numbers per-namespace-instance.  So my container's
> pidns serial might be 0x2, and if it clones a new pidns that would be
> "(0x2,0x1)" on the host, or just 0x1 inside the container.  But we don't
> need that if the simple userspace approach suffices)

This sounds manageable...

- RGB

--
Richard Guy Briggs <rbriggs@xxxxxxxxxx>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545
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