Return-Path: linux-nfs-owner@vger.kernel.org Received: from userp1040.oracle.com ([156.151.31.81]:23123 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755706Ab3KMQNA convert rfc822-to-8bit (ORCPT ); Wed, 13 Nov 2013 11:13:00 -0500 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\)) Subject: Re: [PATCH v2 3/3] nfs: check if gssd is running before attempting to use krb5i auth in SETCLIENTID call From: Chuck Lever In-Reply-To: Date: Wed, 13 Nov 2013 11:12:48 -0500 Cc: Jeff Layton , Linux NFS Mailing List , Neil Brown , Steve Dickson Message-Id: References: <1384353053-30002-1-git-send-email-jlayton@redhat.com> <1384353053-30002-4-git-send-email-jlayton@redhat.com> <1CFBCCB6-37CE-4C49-91EE-0FB33D11B57A@netapp.com> <4226B463-0DB1-4847-9C30-252E67B46859@oracle.com> <20131113103510.6f89a998@corrin.poochiereds.net> To: "Myklebust, Trond" Sender: linux-nfs-owner@vger.kernel.org List-ID: On Nov 13, 2013, at 10:49 AM, "Myklebust, Trond" wrote: > > On Nov 13, 2013, at 10:35, Jeff Layton wrote: > >> On Wed, 13 Nov 2013 10:14:30 -0500 >> Chuck Lever wrote: >> >>> >>> On Nov 13, 2013, at 9:48 AM, "Myklebust, Trond" wrote: >>> >>>> >>>> On Nov 13, 2013, at 9:38, Chuck Lever wrote: >>>> >>>>> >>>>> On Nov 13, 2013, at 9:30 AM, Jeff Layton wrote: >>>>> >>>>>> Currently, the client will attempt to use krb5i in the SETCLIENTID call >>>>>> even if rpc.gssd is running. If that fails, it'll then fall back to >>>>>> RPC_AUTH_UNIX. This introduced a delay when mounting if rpc.gssd isn't >>>>>> running, and causes warning messages to pop up in the ring buffer. >>>>>> >>>>>> Check to see if rpc.gssd is running before even attempting to use krb5i >>>>>> auth, and just silently skip trying to do so if it isn't. >>>>>> >>>>>> Signed-off-by: Jeff Layton >>>>>> --- >>>>>> >>>>>> diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c >>>>>> index b4a160a..988aebf 100644 >>>>>> --- a/fs/nfs/nfs4client.c >>>>>> +++ b/fs/nfs/nfs4client.c >>>>>> @@ -8,6 +8,7 @@ >>>>>> #include >>>>>> #include >>>>>> #include >>>>>> +#include >>>>>> #include >>>>>> #include >>>>>> #include "internal.h" >>>>>> @@ -351,7 +352,7 @@ static int nfs4_init_client_minor_version(struct nfs_client *clp) >>>>>> */ >>>>>> struct nfs_client *nfs4_init_client(struct nfs_client *clp, >>>>>> const struct rpc_timeout *timeparms, >>>>>> - const char *ip_addr) >>>>>> + const char *ip_addr, struct net *net) >>>> >>>> Why the ?struct net? argument? clp->cl_net should already be initialized here. >>>> >>>>>> { >>>>>> char buf[INET6_ADDRSTRLEN + 1]; >>>>>> struct nfs_client *old; >>>>>> @@ -370,7 +371,10 @@ struct nfs_client *nfs4_init_client(struct nfs_client *clp, >>>>>> __set_bit(NFS_CS_INFINITE_SLOTS, &clp->cl_flags); >>>>>> __set_bit(NFS_CS_DISCRTRY, &clp->cl_flags); >>>>>> __set_bit(NFS_CS_NO_RETRANS_TIMEOUT, &clp->cl_flags); >>>>>> - error = nfs_create_rpc_client(clp, timeparms, RPC_AUTH_GSS_KRB5I); >>>>>> + >>>>>> + error = -EINVAL; >>>>>> + if (gssd_running(net)) >>>>>> + error = nfs_create_rpc_client(clp, timeparms,RPC_AUTH_GSS_KRB5I); >>>>>> if (error == -EINVAL) >>>>>> error = nfs_create_rpc_client(clp, timeparms, RPC_AUTH_UNIX); >>>>> >>>>> This feels like a layering violation. Why wouldn't you put a gssd_running check in gss_create(), for example, and have rpcauth_create() return -EINVAL? >>>>> >>>> >>>> It would be better to put it in the upcall. >>> >>> Waiting until the upcall has its benefits. At that point, GSSD (if it is running) can report other errors, such as that there is no material to form a machine credential. >>> >>> My point to Jeff is that, aside from architectural aesthetics, direct calls from RPC consumers to the GSS layer causes a module dependency problem. The right way to plumb this is to create an RPC client API that invokes gssd_running() but only if auth_rpcgss.ko is loaded. > > Chuck, I?ve already told you that the auth_rpcgss dependency is a non-starter. Maybe you thought that in your brain, but look at the e-mail archive: You actually haven't explicitly objected yet. You simply observed that this mechanism doesn't work for built-in scenarios, and I agree with that observation. It isn't supposed to work for built-in. But I don't think you understand my full proposal or my objection to Jeff's third patch. > Turning off automatic loading of rpcsec_gss modules is a _worse_ regression than the ones we already have and (as I already said) can be trivially defeated by just compiling them into the kernel. Automatic loading of auth_rpcgss never worked until 71afa85e (March 16). It simply isn't possible that we've depended on automatic loading of auth_rpcgss.ko in the past, because it has never worked until recently. > We _want_ the kernel to be able to autoload modules so that we can add new security flavours etc without having to recompile. I'm not proposing to turn off automatic loading of the GSS mechanisms. If auth_rpcgss.ko is loaded, the mechanisms get loaded automatically. > >>> However, I don't see why the existing RPC client APIs shouldn't just fail where appropriate if GSSD isn't available. Is there a strong need to expose gssd_running() as a separate API? >>> >> >> One of the complaints about this whole "use krb5i by default" change is >> that we now get the warnings in the ring buffer when gssd isn't >> running. That's a good thing if krb5 was explicitly requested, but is >> useless and confusing if the user just wants to use AUTH_SYS. >> >> If we wait until gss_create, it's too late to know what the "intent" >> was. We'll either fire the warning inappropriately like we do now, or >> miss it altogether when we actually should have printed it. > > What if the user intended to use krb5i, but the daemon failed to start? > This whole ?kernel second guessing what the admin _actually_ wanted to do? thing is a red herring. Let?s just fix the real problem and then leave it at that. I agree that the kernel shouldn't guess. Autoloading auth_rpcgss is guessing what the admin wanted, IMO. -- Chuck Lever chuck[dot]lever[at]oracle[dot]com