Re: Fedora 32 rpc.gssd misbehavior

Steve Dickson
2020-07-30T14:43:19Z

On 7/29/20 2:27 PM, Chuck Lever wrote:
>
>
>> On Jul 29, 2020, at 1:19 PM, Chuck Lever <chuck.lever@oracle.com> wrote:
>>
>> Hi!
>>
>> I recently updated my test systems from EL7 to Fedora 32, and
>> NFSv4.0 with Kerberos has stopped working.
>>
>> I mount with "klimt.ib" as before. The client workload stops
>> dead when the server tries to perform its first CB_RECALL.
>>
>> I added some client instrumentation:
>>
>> kernel: NFSv4: Callback principal (nfs@klimt.ib.1015granger.net) does not match acceptor (nfs@klimt.ib).
>> kernel: NFS: NFSv4 callback contains invalid cred
>>
>> I boosted gssd verbosity, and it says:
>>
>> rpc.gssd[986]: doing downcall: lifetime_rec=72226 acceptor=nfs@klimt.ib
>>
>> But it knows the full hostname for the server:
>>
>> rpc.gssd[986]: Full hostname for 'klimt.ib' is 'klimt.ib.1015granger.net'
>>
>>
>> The acceptor appears to come from the Kerberos library. Shouldn't
>> it be canonicalized? If so, should the Kerberos library do it, or
>> should gssd? Since this behavior appeared after an upgrade, I
>> suspect a Kerberos library regression. But it could be config-
>> related, since both systems were re-imaged from the ground up.
>>
>> Also noticing some other problems on the server (missing hostname
>> strings in debug messages, sssd_kcm infinite loops, and gssd
>> sending garbage to the client after the NULL request that
>> establishes the callback context).
>>
>> But let's look at the client acceptor problem first.
>
> I believe I found the problem.
>
> 8bffe8c5ec1a ("gssd: add /etc/nfs.conf support") added a number of gssd config
> options to /etc/nfs.conf, including "avoid-dns". The default setting of avoid-
> dns is 1. When I set this option on my client system explicitly to 0, NFSv4.0
> with Kerberos works again.
Strange... What is failing in rpc.gssd when it is set to 1?
Maybe it has something to do with your DNS setup?

>
> Is there a reason the default setting is 1?
Looking back... It's always bee set to 1. So no good reason ;-)

steved.
> n
>
> --
> Chuck Lever
>
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