No description, website, or topics provided.
C Perl Shell Logos
Fetching latest commit…
Cannot retrieve the latest commit at this time.


			Linux FedFs Implementation

Maintainer:	Chuck Lever <>
Mailing list:	<>
Web site:
SCM:		git://

Release notes for fedfs-utils 0.10-devel

Release Quality Statement
------- ------- ---------

This is an ALPHA quality release.  The code in this release is not
guaranteed to work.  Programming, administrative, and user interfaces
may change significantly before the next release.  This release is
for technology preview only.

Warning: This package installs an externally visible RPC service that
allows creation and deletion of directories on all areas of a fileserver.
The security features of the FedFS ADMIN server code (RPCSEC GSSAPI)
have not yet been implemented.  Until these features are implemented,
use careful judgement about deploying the FedFS ADMIN RPC service daemon
on production file servers.

Warning: The implementation in this package is based on internet draft
standards that are still evolving.  The current release of fedfs-utils
may not be compatible with the next release of this package, nor with
implementations from other vendors.

Intellectual Property Disclaimer
------------ -------- ----------

The fedfs-utils implementation in this package is copyright 2010,
2011, and 2012 Oracle.  Except where explicitly mentioned, all source
code in this package is covered by version 2 of the GNU General Public
License.  See the COPYING file for details.  A few parts are also
covered by the IETF's code license, which is a simplified BSD license
that is compatible with GPLv2.

In addition:

  IPR disclosure 1362 ( discloses
  coverage of the FedFS NSDB architecture by US Patent #5,842,214:
  "Distributed file system providing a unified name space with
  efficient name resolution," filed by Microsoft Corporation on
  September 24, 1997 but never assigned.  Microsoft has released the
  patent via a Royalty-Free, Reasonable and Non-discriminatory Licence
  to All Implementers.

  IPR disclosure 1634 ( discloses
  coverage of technology in this package by US Patent #7,933,921:
  "Referent-controlled location resolution of resources in a federated
  distributed system," filed on November 29, 2006 and assigned to NetApp
  on April 26, 2011.  NetApp has released the patent via a Royalty-Free,
  Reasonable and Non-discriminatory Licence to All Implementers.

Package Synopsis
------- --------

This package contains an implementation for Linux of the Federated
Filesystem (FedFS) Proposed Standard.  For an introduction to FedFS,
see RFC 5716, or read the fedfs(7) man page provided in the doc/man

Packagers and distributors should review this entire README document
to understand what is in this package, it's pre-requisites, and any
security issues related to it.

An attempt has been made to keep this package distribution-neutral.
It is a source code-only package that is distributed via tarball and


The components in this package are used for managing file system
referrals in order to create a global network file system namespace.

See RFCs 3530bis and 5661 for more details on NFSv4 referrals.  SMB
referrals are described in other documents.  At this point in time,
this package supports only NFSv4 referrals.  SMB referrals may be
supported in a future release.

File system referrals allow a file server to direct clients to other
servers and exports when data has been moved or replicated.  In a larger
sense, they organize a network file system namespace across multiple
file servers.  A federation of file servers can create a seamless global
namespace using referrals.  No configuration changes on clients are
required as the namespace is changed over time.

Installable components include:

   o  An automounter program map to discover the top-level directory
      of FedFS domain namespaces

   o  A mount command to mount parts of a FedFS domain namespace

   o  A plug-in library that allows programs outside of FedFS to
      resolve junctions on local file systems; a header file
      describing the library's API is included

   o  An ONC RPC service daemon that runs on file servers to enable
      remote management of FedFS junctions

   o  A tool called "nfsref" to manage local junctions without
      requiring fedfsd.

   o  A set of command-line clients that can access fedfsd instances
      on remote file servers

   o  A set of command-line clients that can manage FedFS entries on
      an LDAP server acting as a FedFS NSDB

   o  A tool to manage NSDB connection parameters on the local host

   o  An LDIF format schema to enable an LDAP server to support FedFS

The automounter program map is a subcommand invoked by the automounter
to locate FedFS domains and construct appropriate mount options for
mounting domain roots.  It is used in conjunction with the Linux
autofs facility.

The mount command is a subcommand invoked by mount(8) to handle the
housekeeping needed to find and mount part or all of FedFS domain

The plug-in library provides an API for resolving local junctions
into a list of file system locations.  The API is described in a new
header file installed in /usr/include.  A patch to mountd (nfs-utils)
is available to support the use of this plug-in library.

The fedfsd program is an RPC server that allows remote administrators to
create FedFS junctions in local file systems.  FedFS ADMIN requests that
can mutate local file system state are authenticated via RPCSEC GSSAPI
(not yet implemented).  Run this program on NFS file servers that
participate in a FedFS federation to allow the management of FedFS
junctions on that server.

The command-line clients are used by FedFS adminstrators to manage the
state of the local FedFS federation.  These are simple clients that
expose the raw administrative operations of FedFS, much like the bottom-
level git commands.  Eventually we plan to create high-level clients, much
like git porcelain, to provide some degree of automation to FedFS

The INSTALL file in this distribution explains more about how to build
these components, and which of these components to install on what

An Installation Guide has also been provided on the project web site.

Package Version
------- -------

Standard releases:


Major releases introduce new features, and may not always be backwards
compatible with earlier releases.  Minor releases may introduce new
features, but will be backwards compatible with earlier minor releases
with the same major version number.

While we are in alpha, that last rule will be bent or broken.

Operational pre-requisites
----------- --------------

Linux kernel release 3.2 or later with the commit entitled "NFS: fix
bug in legacy DNS resolver." applied.

An entry for the FedFS ADMIN protocol in /etc/rpc:

	fedfs_admin	100418

The fedfsd program requires rpcbind and libtirpc.  In the future, it
will also require correctly configured RPCSEC GSSAPI on the system
where it is running.  For example, to support Kerberos authentication,
Kerberos configuration files would have to be up to date, and a proper
keytab must be established.

Distributors should provide an appropriate init script (or equivalent)
to ensure that fedfsd is started after a system boot.  The contrib/
subdirectory contains samples of init scripts.

The junction plug-in library requires LDAP libraries, libxml2,
libsqlite3, liburiparser, and support for TLS (usually OpenSSL).

nfs-utils release 1.2.6 or later.  mountd may need to be rebuilt on
a system that has /usr/include/nfs-plugin.h installed, in order to
find and execute the junction plug-in library appropriately.

To store FedFS junctions, file systems with run-time support for
extended attributes are required on FedFS-enabled file servers.

libcap is required to permit rpc.fedfsd, nsdbparams, and the junction
plug-in library to access trusted extended attributes in each file

The FedFS ADMIN clients require libtirpc.  In the future, they will
also require correctly configured RPCSEC GSSAPI (usually Kerberos is
the preferred authentication flavor).

NSDB client components require LDAP libraries and support for TLS
(namely, OpenSSL).

NSDB connection parameter information is persistent.  The NSDB
connection parameter database is located by default under
/var/lib/fedfs.  The fedfsd program must have write access to this
directory, and the junction plug-in library and the NSDB clients must
have read access to this directory.  Usually a special user ID and
group ID are created for this purpose.

x.509 certificates for authenticating NSDB nodes are stored under
/var/lib/fedfs/nsdbcerts, by default.  fedfsd and nsdbparams must
have write access to this directory.  The junction plug-in library
and the NSDB clients must have read access to this directory.

Security considerations
-------- --------------

The FedFS network protocols employ standard network security
mechanisms to authenticate servers and administrators.  Therefore,
packaged support for RPCSEC GSSAPI (in the future) and LDAP over TLS
must be installed and configured correctly on the systems running
these programs.  Further discussion of installation and configuration
of these packages is beyond the scope of this document.  (To do:
implement RPCSEC GSSAPI support).

FedFS ADMIN clients contact the FedFS ADMIN server with no
authentication today, but in the future will use RPCGSS security.
The FedFS administrator will authenticate to the ADMIN server when
performing operations that change the persistent state of the ADMIN
and file server (eg. creating junctions or setting NSDB connection

Before performing operations that change the persistent state of an
NSDB node, NSDB clients should authenticate the server using the
server's x.509 certificate.  Binding as an LDAP user with write
authorization to the FedFS entries stored on this server is required
for this class of operations.

Operations on an NSDB node or a FedFS ADMIN service that do not
change persistent domain state are done without authentication of
the requestor (a domain administrator or a fileserver).  The
requestor is not required to bind to the directory for this class
of operations.  The requestor may authenticate the NSDB, however,
using an x.509 certificate.

The FedFS ADMIN server and the junction plug-in library both access
FedFS junctions stored in local file systems.  These junctions are
stored in trusted extended attributes (trusted xattrs).  The
CAP_SYS_ADMIN capability is required for any program that accesses
trusted xattrs.

The fedfsd program is usually started by a parent process running as
root.  Subsequently, fedfsd drops all privileges it does not require
for normal steady state operation.  The fedfsd program is a long-
running system service that listens on a network port and registers
with the local rpcbind service.  Standard precautions should be taken.

The junction plug-in library assumes that mountd is running as root.
Since it only reads junctions on behalf of mountd, this should typically
be secure against network attack.

As a consequence of their privilege requirements, these programs must
be registered with local security auditing subsystems such as SELinux.