Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx11.netapp.com ([216.240.18.76]:4430 "EHLO mx11.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752998Ab3IEPRi convert rfc822-to-8bit (ORCPT ); Thu, 5 Sep 2013 11:17:38 -0400 From: "Adamson, Dros" To: Dr James Bruce Fields CC: "Myklebust, Trond" , "Adamson, Dros" , linux-nfs list Subject: Re: [PATCH] NFSv4: use mach cred for SECINFO_NO_NAME w/ integrity Date: Thu, 5 Sep 2013 15:17:37 +0000 Message-ID: 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> In-Reply-To: <20130905140718.GI10232@fieldses.org> Content-Type: text/plain; charset="Windows-1252" MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: 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. -dros