2008-09-10 09:24:13

by Cedric Le Goater

[permalink] [raw]
Subject: Re: [RFC][PATCH] sunrpc: fix oops in rpc_create() when the mount namespace is unshared

Eric W. Biederman wrote:
> Chuck Lever <[email protected]> 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

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