Re: [RFC][PATCH 2/4] sunrpc: Use utsnamespaces

[Chuck Lever]

On Jan 6, 2009, at Jan 6, 2009, 3:02 PM, Serge E. Hallyn wrote:
> Quoting Matt Helsley (matthltc@xxxxxxxxxx):
> > We can often specify the UTS namespace to use when starting an RPC  
> > client.
> > However sometimes no UTS namespace is available (specifically  
> > during system
> > shutdown as the last NFS mount in a container is unmounted) so fall
> > back to the initial UTS namespace.
>
> So what happens if we take this patch and do nothing else?

I thought the point of this was to prevent incorrect container  
nodenames from leaking onto the network.

> The only potential problem situation will be rpc requests
> made on behalf of a container in which the last task has
> exited, right?  So let's say a container did an nfs mount
> and then exits, causing an nfs umount request.
>
> That umount request will now be sent with the wrong nodename.
> Does that actually cause problems, will the server use the
> nodename to try and determine the client sending the request?
>
> thanks,
> -serge
>
> > Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx>
> > Cc: Cedric Le Goater <clg@xxxxxxxxxx>
> > Cc: Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>
> > Cc: linux-nfs@xxxxxxxxxxxxxxx
> > Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxx>
> > Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
> > Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> > Cc: Linux Containers <containers@xxxxxxxxxxxxxx>
> >
> > ---
> > net/sunrpc/clnt.c |    7 +++++--
> > 1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > Index: linux-2.6.28/net/sunrpc/clnt.c
> > ===================================================================
> > --- linux-2.6.28.orig/net/sunrpc/clnt.c
> > +++ linux-2.6.28/net/sunrpc/clnt.c
> > @@ -128,6 +128,7 @@ static struct rpc_clnt * rpc_new_client(
> > 	struct rpc_version	*version;
> > 	struct rpc_clnt		*clnt = NULL;
> > 	struct rpc_auth		*auth;
> > +	struct new_utsname	*uts_ns = init_utsname();
> > 	int err;
> > 	size_t len;
> >
> > @@ -213,10 +214,12 @@ static struct rpc_clnt * rpc_new_client(
> > 	}
> >
> > 	/* save the nodename */
> > -	clnt->cl_nodelen = strlen(init_utsname()->nodename);
> > +	if (current->nsproxy != NULL)
> > +		uts_ns = utsname();
> > +	clnt->cl_nodelen = strlen(uts_ns->nodename);
> > 	if (clnt->cl_nodelen > UNX_MAXNODENAME)
> > 		clnt->cl_nodelen = UNX_MAXNODENAME;
> > -	memcpy(clnt->cl_nodename, init_utsname()->nodename, clnt- 
> > >cl_nodelen);
> > +	memcpy(clnt->cl_nodename, uts_ns->nodename, clnt->cl_nodelen);
> > 	rpc_register_client(clnt);
> > 	return clnt;
> >
> >
> > --
> > _______________________________________________
> > Containers mailing list
> > Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > https://lists.linux-foundation.org/mailman/listinfo/containers

--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com




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