Date: Thu, 16 Sep 2004 20:33:15 +0200
From: Herbert Poetzl <herbert@13thfloor.at>
To: Greg KH <greg@kroah.com>
Cc: Robert Love <rml@novell.com>, Tim Hockin <thockin@hockin.org>,
       Kay Sievers <kay.sievers@vrfy.org>, akpm@osdl.org,
       linux-kernel@vger.kernel.org
Subject: Re: [patch] kernel sysfs events layer
Message-ID: <20040916183315.GB31479@MAIL.13thfloor.at>
Mail-Followup-To: Greg KH <greg@kroah.com>,
	Robert Love <rml@novell.com>, Tim Hockin <thockin@hockin.org>,
	Kay Sievers <kay.sievers@vrfy.org>, akpm@osdl.org,
	linux-kernel@vger.kernel.org
References: <1095281358.23385.109.camel@betsy.boston.ximian.com> <20040915205643.GA19875@hockin.org> <20040915212322.GB25840@kroah.com> <1095283589.23385.117.camel@betsy.boston.ximian.com> <20040915213419.GA21899@hockin.org> <1095284320.23385.123.camel@betsy.boston.ximian.com> <20040916012104.GA21832@MAIL.13thfloor.at> <20040916040820.GA5395@kroah.com> <20040916141008.GA28893@MAIL.13thfloor.at> <20040916150803.GB343@kroah.com>
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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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