Re: [PATCH nfs-utils] exportfs: make "insecure" the default for all exports

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2025-06-04 at 14:26 -0400, Steve Dickson wrote:
> Hello all,
> 
> On 5/13/25 9:50 AM, Jeff Layton wrote:
> > Back in the 80's someone thought it was a good idea to carve out a set
> > of ports that only privileged users could use. When NFS was originally
> > conceived, Sun made its server require that clients use low ports.
> > Since Linux was following suit with Sun in those days, exportfs has
> > always defaulted to requiring connections from low ports.
> > 
> > These days, anyone can be root on their laptop, so limiting connections
> > to low source ports is of little value.
> > 
> > Make the default be "insecure" when creating exports.
> > 
> > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > ---
> > In discussion at the Bake-a-thon, we decided to just go for making
> > "insecure" the default for all exports.
> > ---
> >   support/nfs/exports.c      | 7 +++++--
> >   utils/exportfs/exports.man | 4 ++--
> >   2 files changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/support/nfs/exports.c b/support/nfs/exports.c
> > index 21ec6486ba3d3945df0800972ba1dfd03bd65375..69f8ca8b5e2ed50b837ef287ca0685af3e70ed0b 100644
> > --- a/support/nfs/exports.c
> > +++ b/support/nfs/exports.c
> > @@ -34,8 +34,11 @@
> >   #include "reexport.h"
> >   #include "nfsd_path.h"
> >   
> > -#define EXPORT_DEFAULT_FLAGS	\
> > -  (NFSEXP_READONLY|NFSEXP_ROOTSQUASH|NFSEXP_GATHERED_WRITES|NFSEXP_NOSUBTREECHECK)
> > +#define EXPORT_DEFAULT_FLAGS	(NFSEXP_READONLY |	\
> > +				 NFSEXP_ROOTSQUASH |	\
> > +				 NFSEXP_GATHERED_WRITES |\
> > +				 NFSEXP_NOSUBTREECHECK | \
> > +				 NFSEXP_INSECURE_PORT)
> >   
> >   struct flav_info flav_map[] = {
> >   	{ "krb5",	RPC_AUTH_GSS_KRB5,	1},
> > diff --git a/utils/exportfs/exports.man b/utils/exportfs/exports.man
> > index 39dc30fb8290213990ca7a14b1b3971140b0d120..0b62bb3a82b0e74bc2a7eb84301c4ec97b14d003 100644
> > --- a/utils/exportfs/exports.man
> > +++ b/utils/exportfs/exports.man
> > @@ -180,8 +180,8 @@ understands the following export options:
> >   .TP
> >   .IR secure
> >   This option requires that requests not using gss originate on an
> > -Internet port less than IPPORT_RESERVED (1024). This option is on by default.
> > -To turn it off, specify
> > +Internet port less than IPPORT_RESERVED (1024). This option is off by default
> > +but can be explicitly disabled by specifying
> >   .IR insecure .
> >   (NOTE: older kernels (before upstream kernel version 4.17) enforced this
> >   requirement on gss requests as well.)
> > 
> > ---
> > base-commit: 2cf015ea4312f37598efe9733fef3232ab67f784
> > change-id: 20250513-master-89974087bb04
> > 
> > Best regards,
> My apologies but I got a bit lost in the fairly large thread
> What as is consensus on this patch? Thumbs up or down.
> Will there be a V2?
> 
> I'm wondering what type documentation impact this would
> have on all docs out there that say one has to be root
> to do the mount.
> 
> I guess I'm not against the patch but as Neil pointed
> out making things insecure is a different direction
> that the rest of the world is going.
> 
> my two cents,
> 
> 

Thumbs down for now. Neil argued for a more measured approach to
changing this.

I started work on a manpage patch for exports(5) but it's not quite
ready yet. I also want to look at converting some manpages to asciidoc
as we go, to make future updates easier.
-- 
Jeff Layton <jlayton@kernel.org>