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 <dros@xxxxxxxxxx>
> ---
>
> 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;
> }
I have a question: if we use the machine credential, don't we risk a
NFS4ERR_ACCESS due to the directory permission settings?
I don't see anything in the spec about what permissions you do need for
a SECINFO_NO_NAME, but since NFS4ERR_ACCESS is listed as a valid return
code, I'm assuming that the server may enforce lookup permissions...
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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