Re: [patch] kernel sysfs events layer

[Herbert Poetzl <herbert@13thfloor.at>]

On Thu, Sep 16, 2004 at 08:08:05AM -0700, Greg KH wrote:
> On Thu, Sep 16, 2004 at 04:10:08PM +0200, Herbert Poetzl wrote:
> > On Wed, Sep 15, 2004 at 09:08:21PM -0700, Greg KH wrote:
> > > On Thu, Sep 16, 2004 at 03:21:04AM +0200, Herbert Poetzl wrote:
> > > > On Wed, Sep 15, 2004 at 05:38:39PM -0400, Robert Love wrote:
> > > > > On Wed, 2004-09-15 at 14:34 -0700, Tim Hockin wrote:
> > > > > 
> > > > > > It's a can of worms, is what it is.  And I'm not sure what a good fix
> > > > > > would be.  Would it just be enough to send a generic "mount-table changed"
> > > > > > event, and let userspace figure out the rest?
> > > > > 
> > > > > "Can of worms" is a tough description for something that there is no
> > > > > practical security issue for, just a lot of hand waving.  No one even
> > > > > uses name spaces.
> > > > 
> > > > ah, sorry, that is wrong, we (linux-vserver)
> > > > _do_ use namespaces extensively, and probably 
> > > > other 'jail' solutions will use it too ...
> > > 
> > > Great.  
> > > So, how do you handle the /sbin/hotplug call today?  
> > 
> > most of the time, not at all, but if, then in the
> > 'initial' namespace where other userspace helpers
> > are handled too (means on the host)
> 
> Ok, then you could handle the kevent message the same way, right?

yes probably ...

> > > How would you want to handle this kevent notifier?
> > 
> > if there was a notifier telling about mounts - real
> > and virtual - then they would make sense _inside_
> > the respective namespace they happen .. e.g.
> > 
> > usb-device attached: 
> >   helper is called on host, and does some stuff
> >   result is a mount of some device, which happens
> >   on the host/initial namespace, notifier happens
> >   there ...
> > 
> > process in namespace does --bind mount:
> >   this might be interesting for the host too, but
> >   probably it is more useful for the namespace
> >   where it happened ... 
> 
> But in which namespace did it happen?  That's probaby the hard part to
> determine, right?

well, in the mount --bind case, not really, because
the current process already identifies a namespace
which could be used for that ...

best,
Herbert

> thanks,
> 
> greg k-h
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