On Tue, 2009-01-06 at 15:20 -0500, J. Bruce Fields wrote:
> On Tue, Jan 06, 2009 at 02:02:29PM -0600, Serge E. Hallyn wrote:
> > Quoting Matt Helsley (matth...@us.ibm.com):
> > > 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?
> >
> > 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?
>
> This is just the machine name in the auth_unix credential? The linux
> server ignores that completely (for the purpose of auth_unix
> authenication, it identifies clients only by source ip address). I
> suspect other servers also ignore it, but I don't know.
>
> --b.
I was wondering about this because I kept coming back to the question of
how the server could trust the name the client supplies (seems it
can't). This is very useful information -- it certainly suggests that
this patch would be sufficient.
Thanks!
Cheers,
-Matt Helsley
> >
> > thanks,
> > -serge
> >
> > > Signed-off-by: Matt Helsley <matth...@us.ibm.com>
> > > Cc: Cedric Le Goater <c...@fr.ibm.com>
> > > Cc: Linux Kernel Mailing List <linux-ker...@vger.kernel.org>
> > > Cc: linux-...@vger.kernel.org
> > > Cc: Trond Myklebust <trond.mykleb...@fys.uio.no>
> > > Cc: Chuck Lever <chuck.le...@oracle.com>
> > > Cc: Eric W. Biederman <ebied...@xmission.com>
> > > Cc: Linux Containers <contain...@lists.osdl.org>
> > >
> > > ---
> > > 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
> > > contain...@lists.linux-foundation.org
> > > https://lists.linux-foundation.org/mailman/listinfo/containers
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