Re: kerberized NFSv4 client reporting operation not permitted when mounting with sec=sys

["Benjamin Coddington" <bcodding@redhat.com>]

On 22 Jan 2020, at 4:22, Felix Rubio wrote:

> Hi everybody,
>
> I have a kerberized NFSv4 server that is exporting a mountpoint:
>
>     /home 10.0.0.0/8(rw,no_subtree_check,sec=krb5:krb5i:krb5p)
>
> if I mount that export with this command on the client, it works as 
> expected:
>
>     /sbin/mount.nfs4 NFS.domain:/home /network/home -o 
> _netdev,noatime,hard,sec=krb5
>
> However, if I modify the export to be
>
>     /home 10.0.0.0/8(rw,no_subtree_check,sec=sys:krb5:krb5i:krb5p)
>
> and I mount that export with sec=sys, as
>
>     /sbin/mount.nfs4 NFS.domain:/home /network/home -o 
> _netdev,noatime,hard,sec=sys
>
> I get the following error:
>
>     mount.nfs4: timeout set for Fri Jan 17 14:11:32 2020
>     mount.nfs4: trying text-based options 
> 'hard,sec=sys,vers=4.1,addr=10.2.2.9,clientaddr=10.2.0.12'
>     mount.nfs4: mount(2): Operation not permitted
>     mount.nfs4: Operation not permitted
>
> What might be the reason for this behavior?

Hi Felix,

I don't know.  Can you get more information?  Try again after `rpcdebug 
-m
nfs -s mount`.  That will turn up debugging for messages labeled for 
mount,
and the output will be in the kernel log.  There are other facilities 
there,
see rpcdebug(8).

Another good option is getting a network capture of the mount attempt 
and
trying to figure out if the server is returning an error, or the client 
is
generating the error.

There are also a lot of "nfs", "nfs4", and "rpc" tracepoints you can 
enable
to get more information.

Ben