Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx11.netapp.com ([216.240.18.76]:17696 "EHLO mx11.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964927Ab3IDQsQ convert rfc822-to-8bit (ORCPT ); Wed, 4 Sep 2013 12:48:16 -0400 From: "Adamson, Dros" To: "Myklebust, Trond" CC: linux-nfs list Subject: Re: [PATCH] NFSv4: use mach cred for SECINFO_NO_NAME w/ integrity Date: Wed, 4 Sep 2013 16:48:14 +0000 Message-ID: References: <1378311199-1695-1-git-send-email-dros@netapp.com> <1378311850.3527.16.camel@leira.trondhjem.org> In-Reply-To: <1378311850.3527.16.camel@leira.trondhjem.org> Content-Type: text/plain; charset="Windows-1252" MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: 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). -dros > >> + >> switch (err) { >> case 0: >> case -NFS4ERR_WRONGSEC: > > -- > Trond Myklebust > Linux NFS client maintainer > > NetApp > Trond.Myklebust@netapp.com > www.netapp.com