Re: [PATCH 0/4] nfs/nfsd/sunrpc: enforce requirement for congestion control protocols in NFSv4

[Jeff Layton <jlayton@poochiereds.net>]

On Thu, 2017-02-23 at 12:03 -0500, Jeff Layton wrote:
> RFC5661 says:
> 
>    Where an NFSv4.1 implementation supports operation over the IP
>    network protocol, any transport used between NFS and IP MUST be among
>    the IETF-approved congestion control transport protocols.
> 
> ...and RFC7530 has similar verbiage. The NFS server has never enforced
> this requirement, however, so a user could issue NFSv4 calls against
> the server via UDP.
> 
> This patchset adds a small bit of infrastructure to the sunrpc layer
> to enforce this requirement, and has the nfs and nfsd layers set the
> appropriate flags for it. It also has knfsd skip registering a UDP
> port for NFSv4, using the same flags.
> 
> Lightly tested by hand, but it's fairly straightforward.
> 
> Jeff Layton (4):
>   sunrpc: flag transports as using IETF approved congestion control
>     protocols
>   sunrpc: turn bitfield flags in svc_version into bools
>   nfs/nfsd/sunrpc: enforce congestion control protocol requirement for
>     NFSv4
>   sunrpc: don't register UDP port with rpcbind when version needs
>     congestion control
> 
>  fs/nfs/callback_xdr.c                    |  6 ++++--
>  fs/nfsd/nfs2acl.c                        |  1 -
>  fs/nfsd/nfs3acl.c                        |  1 -
>  fs/nfsd/nfs4proc.c                       | 13 +++++++------
>  include/linux/sunrpc/svc.h               | 12 ++++++++----
>  include/linux/sunrpc/svc_xprt.h          |  1 +
>  net/sunrpc/svc.c                         | 22 +++++++++++++++++++++-
>  net/sunrpc/svcsock.c                     |  1 +
>  net/sunrpc/xprtrdma/svc_rdma_transport.c |  2 ++
>  9 files changed, 44 insertions(+), 15 deletions(-)
> 

I probably should have sent this as an RFC first. I'm not 100% clear on
whether PROG_MISMATCH is the right return code there.

Also, there is still a small wart after this patchset. The high/low
program versions reported look a little odd:

    $ rpcinfo -T udp knfsdsrv nfs 4
    rpcinfo: RPC: Program/version mismatch; low version = 3, high version = 4
    program 100003 version 4 is not available

We could try to fix this and report different values depending on the
socket type, but I'm not sure I really care. AFAIK, this is just
informative anyway, and it's not _technically_ wrong. The server does
support version 4, just not the UDP socket where we sent the RPC ping.

Thoughts?
-- 
Jeff Layton <jlayton@poochiereds.net>