Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([174.143.236.118]:46170 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753548Ab3IERWr (ORCPT ); Thu, 5 Sep 2013 13:22:47 -0400 Date: Thu, 5 Sep 2013 13:22:41 -0400 From: Dr James Bruce Fields To: "Adamson, Dros" Cc: "Myklebust, Trond" , linux-nfs list Subject: Re: [PATCH] NFSv4: use mach cred for SECINFO_NO_NAME w/ integrity Message-ID: <20130905172241.GA23777@fieldses.org> References: <1378311199-1695-1-git-send-email-dros@netapp.com> <1378311850.3527.16.camel@leira.trondhjem.org> <1378341909.6143.1.camel@leira.trondhjem.org> <20130905140718.GI10232@fieldses.org> <20130905153121.GJ10232@fieldses.org> <316C2554-07BD-4DB1-9BA2-4956C83680D0@netapp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: <316C2554-07BD-4DB1-9BA2-4956C83680D0@netapp.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, Sep 05, 2013 at 05:05:09PM +0000, Adamson, Dros wrote: > > On Sep 5, 2013, at 11:31 AM, Dr James Bruce Fields wrote: > > > On Thu, Sep 05, 2013 at 03:17:37PM +0000, Adamson, Dros wrote: > >> > >> On Sep 5, 2013, at 10:07 AM, Dr James Bruce Fields wrote: > >> > >>> On Thu, Sep 05, 2013 at 12:45:09AM +0000, Myklebust, Trond wrote: > >>>> On Wed, 2013-09-04 at 16:48 +0000, Adamson, Dros wrote: > >>>>> On Sep 4, 2013, at 12:24 PM, "Myklebust, Trond" wrote: > >>>>> > >>>>>> On Wed, 2013-09-04 at 12:13 -0400, Weston Andros Adamson wrote: > >>>>>>> Commit 97431204ea005ec8070ac94bc3251e836daa7ca7 introduced a regression > >>>>>>> that causes SECINFO_NO_NAME to fail without sending an RPC if: > >>>>>>> > >>>>>>> 1) the nfs_client's rpc_client is using krb5i/p (now tried by default) > >>>>>>> 2) the current user doesn't have valid kerberos credentials > >>>>>>> > >>>>>>> This situation is quite common - as of now a sec=sys mount would use > >>>>>>> krb5i for the nfs_client's rpc_client and a user would hardly be faulted > >>>>>>> for not having run kinit. > >>>>>>> > >>>>>>> The solution is to use the machine cred when trying to use an integrity > >>>>>>> protected auth flavor for SECINFO_NO_NAME. > >>>>>>> > >>>>>>> Older servers may not support using the machine cred or an integrity > >>>>>>> protected auth flavor for SECINFO_NO_NAME in every circumstance, so we fall > >>>>>>> back to using the user's cred and the filesystem's auth flavor in this case. > >>>>>>> > >>>>>>> We run into another problem when running against linux nfs servers - > >>>>>>> they return NFS4ERR_WRONGSEC when using integrity auth flavor (unless the > >>>>>>> mount is also that flavor) even though that is not a valid error for > >>>>>>> SECINFO*. Even though it's against spec, handle WRONGSEC errors on > >>>>>>> SECINFO_NO_NAME by falling back to using the user cred and the > >>>>>>> filesystem's auth flavor. > >>>>>>> > >>>>>>> Signed-off-by: Weston Andros Adamson > >>>>>>> --- > >>>>>>> > >>>>>>> This patch goes along with yesterday's SECINFO patch > >>>>>>> > >>>>>>> fs/nfs/nfs4proc.c | 41 +++++++++++++++++++++++++++++++++++++---- > >>>>>>> 1 file changed, 37 insertions(+), 4 deletions(-) > >>>>>>> > >>>>>>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c > >>>>>>> index ab1461e..74b37f5 100644 > >>>>>>> --- a/fs/nfs/nfs4proc.c > >>>>>>> +++ b/fs/nfs/nfs4proc.c > >>>>>>> @@ -7291,7 +7291,8 @@ out: > >>>>>>> */ > >>>>>>> static int > >>>>>>> _nfs41_proc_secinfo_no_name(struct nfs_server *server, struct nfs_fh *fhandle, > >>>>>>> - struct nfs_fsinfo *info, struct nfs4_secinfo_flavors *flavors) > >>>>>>> + struct nfs_fsinfo *info, > >>>>>>> + struct nfs4_secinfo_flavors *flavors, bool use_integrity) > >>>>>>> { > >>>>>>> struct nfs41_secinfo_no_name_args args = { > >>>>>>> .style = SECINFO_STYLE_CURRENT_FH, > >>>>>>> @@ -7304,8 +7305,23 @@ _nfs41_proc_secinfo_no_name(struct nfs_server *server, struct nfs_fh *fhandle, > >>>>>>> .rpc_argp = &args, > >>>>>>> .rpc_resp = &res, > >>>>>>> }; > >>>>>>> - return nfs4_call_sync(server->nfs_client->cl_rpcclient, server, &msg, > >>>>>>> - &args.seq_args, &res.seq_res, 0); > >>>>>>> + struct rpc_clnt *clnt = server->client; > >>>>>>> + int status; > >>>>>>> + > >>>>>>> + if (use_integrity) { > >>>>>>> + clnt = server->nfs_client->cl_rpcclient; > >>>>>>> + msg.rpc_cred = nfs4_get_clid_cred(server->nfs_client); > >>>>>>> + } > >>>>>>> + > >>>>>>> + dprintk("--> %s\n", __func__); > >>>>>>> + status = nfs4_call_sync(clnt, server, &msg, &args.seq_args, > >>>>>>> + &res.seq_res, 0); > >>>>>>> + dprintk("<-- %s status=%d\n", __func__, status); > >>>>>>> + > >>>>>>> + if (msg.rpc_cred) > >>>>>>> + put_rpccred(msg.rpc_cred); > >>>>>>> + > >>>>>>> + return status; > >>>>>>> } > >>>>>>> > >>>>>>> static int > >>>>>>> @@ -7315,7 +7331,24 @@ nfs41_proc_secinfo_no_name(struct nfs_server *server, struct nfs_fh *fhandle, > >>>>>>> struct nfs4_exception exception = { }; > >>>>>>> int err; > >>>>>>> do { > >>>>>>> - err = _nfs41_proc_secinfo_no_name(server, fhandle, info, flavors); > >>>>>>> + /* first try using integrity protection */ > >>>>>>> + err = -NFS4ERR_WRONGSEC; > >>>>>>> + > >>>>>>> + /* try to use integrity protection with machine cred */ > >>>>>>> + if (_nfs4_is_integrity_protected(server->nfs_client)) > >>>>>>> + err = _nfs41_proc_secinfo_no_name(server, fhandle, info, > >>>>>>> + flavors, true); > >>>>>>> + > >>>>>>> + /* > >>>>>>> + * if unable to use integrity protection, or SECINFO with > >>>>>>> + * integrity protection returns NFS4ERR_WRONGSEC (which is > >>>>>>> + * disallowed by spec, but exists in deployed servers) use > >>>>>>> + * the current filesystem's rpc_client and the user cred. > >>>>>>> + */ > >>>>>>> + if (err == -NFS4ERR_WRONGSEC) > >>>>>>> + err = _nfs41_proc_secinfo_no_name(server, fhandle, info, > >>>>>>> + flavors, false); > >>>>>> > >>>>>> As I said yesterday, RFC5661 forbids SECINFO_NO_NAME from returning > >>>>>> NFS4ERR_WRONGSEC, so this is 100% equivalent to > >>>>>> > >>>>>> if (!_nfs4_is_integrity_protected()) > >>>>>> err = …. > >>>>> > >>>>> Right, but I thought we were doing this to support server implementations like linux that *do* return NFS4ERR_WRONGSEC on SECINFO_NO_NAME even though it's forbidden. I know we normally don't work around server bugs, but this seems pretty simple. > >>>>> > >>>>> If we don't do this, then SECINFO_NO_NAME will always fail against current linux severs no matter what the mount options - unless krb5i/p is unusable (not configured, time skew, no machine cred, etc). > >>>> > >>>> Bruce, you're it: what's the deal here? > >>> > >>> Dros, in what cases exactly do you see SECINFO_NO_NAME returning > >>> WRONGSEC? > >>> > >>> From a quick skim of the code it looks like it shouldn't happen in the > >>> CURRENT_FH case, which is the one the client uses. But I probably > >>> overlooked something.... > >>> > >>> --b. > >> > >> SECINFO_NO_NAME will fail with NFS4ERR_WRONGSEC in check_nfsd_access when the rpc auth flavor is different from the export's auth flavor - in the same way as SECINFO. > > > > Huh. There's no check_nfsd_access call in secinfo_no_name in the > > CURRENT_FH case. And any checks on the putfh op should be turned off by > > the OP_HANDLES_WRONGSEC flag on secinfo_no_name. > > > > But I haven't actually tried it, and presumably you have (any hints on > > reproducing?), so I'll take a look.... > > > > --b. > > You may be right here - I'm pretty sure I saw SECINFO_NO_NAME fail like this, but I'm not 100%. I'll try to reproduce and report back. OK, thanks.--b.