Re: [PATCH v2 0/4] nfs/nfsd/sunrpc: enforce NFSv4 transport requirements

["J. Bruce Fields" <bfields@fieldses.org>]

On Mon, Feb 27, 2017 at 07:55:55AM -0500, Jeff Layton wrote:
> On Mon, 2017-02-27 at 07:08 -0500, Tom Talpey wrote:
> > On 2/27/2017 6:59 AM, Jeff Layton wrote:
> > > What we'd need to make that happen, I think is a [global] stanza in
> > > nfs.conf with a single 'nfsd_v3' boolean that defaults to off. If
> > 
> > Don't forget v2! And maybe even v4.0 if you're encouraging non-legacy
> > operation. RFC3530 was published 14 years ago, btw. RFC1813 in 1995,
> > and RFC1094 in 1989.

Looking just at the RHEL history.... I think we enabled experimental v4
in 2005 in RHEL4, but regretted that.  It wasn't a default until RHEL6
in 2010.  Other OS's were different, but in general I think
implementation lagged specification by a lot.  Ditto to some degree for
4.1.

> I think v2 already defaults to off these days? But yeah, I could see us
> adding a similar boolean for v2. Maybe we don't need a new switch at
> all, and just need to have everything look at the [nfsd] vers2= and
> vers3= config file options?
> 
> I think wiring nfsd and mountd up properly for this would be fairly easy
> here. statd is a little tougher since we don't want to run it or sm-
> notify at all if v2/3 are disabled. I wonder if there is any way we can
> make systemd look at this config file and decide whether to start statd
> based on whether either of those options is set?

Neil might have ideas--see https://lwn.net/Articles/701549/.

--b.

> I'd have no issue with eventually defaulting with v4.0 disabled as well,
> but there are a fair number of clients in the field that don't support
> v4.1 (or don't support it well). I think we'd need to wait and see how
> much grief we get about disabling v3 by default before we go there.