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SubjectRe: [RFC][PATCH] sunrpc: fix oops in rpc_create() when the mount namespace is unshared
Eric W. Biederman wrote:
> Chuck Lever <chuck.lever@oracle.com> writes:
>
>> If the upper layers are responsible for providing the utsname, you will need to
>> fix up lockd and the NFS server's callback client too, at least.
>
> Actually looking at the code. It looks like a proper fix may be even simpler.
> Why do we have both clnt->cl_server and clnt->cl_nodename? Or is cl_server
> the other side of the connection?
>
>>>> What are we trying to achieve by reading utsname?
>>> It looks like it gets copied into the sunrpc messages so I assume it is
>>> a part of the sunrpc spec?
>> It appears to be used only for RPC's AUTH_SYS credentials. The nodename is used
>> to identify the caller's host. See RFC 1831, Appendix A:
>>
>> http://rfclibrary.hosting.com/rfc/rfc1831/rfc1831-16.asp
>
> Thanks that helps a lot.
>
>> I'm not terribly familiar with uts namespaces, though. Can someone explain why
>> we need to distinguish between these for AUTH_SYS if the caller is on a remote
>> system?
>
> Semantically processes in different uts namespaces are on different machines.
>
>> I don't like the idea of an oops in here. Instead, (for now) it should warn and
>> fail to create the client, IMO.
>
> Which is interesting when the problem happens during NFS unmount. Although
> frankly it could fail anyway.
>
> It seems strange that we are creating a client during unmount anyway.

the task exiting brings down the lockd thread and unregisters the lockd service
with the portmapper. This is done with a rpc call which creates a client and a
request.

that's how I understand the code and the oops.


C.


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