Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([174.143.236.118]:60541 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753977Ab3IEPbZ (ORCPT ); Thu, 5 Sep 2013 11:31:25 -0400 Date: Thu, 5 Sep 2013 11:31:21 -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: <20130905153121.GJ10232@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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: 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.