From: Cedric Le Goater Subject: Re: [RFC][PATCH] sunrpc: fix oops in rpc_create() when the mount namespace is unshared Date: Wed, 10 Sep 2008 11:23:05 +0200 Message-ID: <48C791F9.8090606@fr.ibm.com> References: <48C52B29.4020204@fr.ibm.com> <20080909124311.GA10053@us.ibm.com> <20080909152952.GA21207@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Chuck Lever , "Serge E. Hallyn" , Andrew Morton , Trond Myklebust , Linux Kernel Mailing List , Linux Containers , linux-nfs@vger.kernel.org To: "Eric W. Biederman" Return-path: Received: from mtagate7.de.ibm.com ([195.212.29.156]:60525 "EHLO mtagate7.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751288AbYIJJYN (ORCPT ); Wed, 10 Sep 2008 05:24:13 -0400 In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: Eric W. Biederman wrote: > Chuck Lever 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.