Re: [PATCH 4/4] net: Implement the per network namespace sysctl infrastructure

From: "Serge E. Hallyn" <serue@us.ibm.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Serge E. Hallyn" <serue@us.ibm.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Andrew Morton <akpm@linux-foundation.org>,
	Daniel Lezcano <dlezcano@fr.ibm.com>,
	Cedric Le Goater <clg@fr.ibm.com>,
	Linux Containers <containers@lists.osdl.org>,
	Pavel Emelyanov <xemul@openvz.org>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	David Miller <davem@davemloft.net>
Subject: Re: [PATCH 4/4] net: Implement the per network namespace sysctl infrastructure
Date: Fri, 30 Nov 2007 18:01:50 -0600	[thread overview]
Message-ID: <20071201000150.GA18758@sergelap.austin.ibm.com> (raw)
In-Reply-To: <m13aun9zfe.fsf@ebiederm.dsl.xmission.com>

Quoting Eric W. Biederman (ebiederm@xmission.com):
> "Serge E. Hallyn" <serue@us.ibm.com> writes:
> 
> >
> > Hey Eric,
> >
> > the patches look nice.
> >
> > The hand-forcing of the passed-in net_ns into a copy of current->nsproxy
> > does make it seem like nsproxy may not be the best choice of what to
> > pass in.  Doesn't only net_sysctl_root->lookup() look at the argument?
> 
> Yes.  Although I call it from __register_sysctl_paths.
> 
> > But I assume you don't want to be more general than sending in a
> > nsproxy so as to dissuade abuse of this interface for needlessly complex
> > sysctl interfaces?
> 
> A bit of that.  I would love to pass in a task_struct so you can use
> anything from a task.  The trouble is I don't have any task_structs or
> nsproxys with the proper value at the point where I am first setting
> this up.  Further I have to have the full sysctl lookup working or I
> could not call sysctl_check.
> 
> > (Well I expect that'll become clear once the the patches using this
> > come out.)
> >
> > Are you planning to use this infrastructure for the uts and ipc
> > sysctls as well?
> 
> Yes.  Where it comes in especially useful, is I can move /proc/sys
> to /proc/sys/<tgid>/task/<pid>/sys.  And get a particular processes
> view of sysctl.  
> 
> We also get a little more reuse of common functions.
> 
> Otherwise Pavel does have a point that using this for uts and ipc
> is not a savings lines of code wise.
> 
> After having seen Pavel changes I am asking myself if there is a sane
> way to remove the ctl_name argument from the ctl_path.
> 
> Anyway where I am with the nsproxy question was that I don't
> see anything easily better.  What I have works and gets the job
> done, and doesn't have any module unload races or holes where a sloppy
> programmer can mess up the sysctl tree.  We needed a solution.
> Trying any harder to find something better would take ages.  So
> I figured this implementation was good enough.

I agree.  So it's already in -mm but still

Acked-by: Serge Hallyn <serue@us.ibm.com>

thanks,
-serge