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wallet release 0.10
(secure data management system)
Written by Russ Allbery <rra@stanford.edu>
Copyright 2006, 2007, 2008, 2009, 2010 Board of Trustees, Leland
Stanford Jr. University. This software is distributed under a BSD-style
license. Please see the file LICENSE in the distribution for more
information.
This software is beta-quality and should be treated with caution. It is
currently being tested for production deployment at Stanford.
BLURB
The wallet is a system for managing secure data, authorization rules to
retrieve or change that data, and audit rules for documenting actions
taken on that data. Objects of various types may be stored in the
wallet or generated on request and retrieved by authorized users. The
wallet tracks ACLs, metadata, and trace information. It is built on top
of the remctl protocol and uses Kerberos GSS-API authentication. One of
the object types it supports is Kerberos keytabs, making it suitable as
a user-accessible front-end to Kerberos kadmind with richer ACL and
metadata operations.
DESCRIPTION
The wallet is a client/server system using a central server with a
supporting database and a stand-alone client that can be widely
distributed to users. The server runs on a secure host with access to a
local database; tracks object metadata such as ACLs, attributes,
history, expiration, and ownership; and has the necessary access
privileges to create wallet-managed objects in external systems (such as
Kerberos service principals). The client uses the remctl protocol to
send commands to the server, store and retrieve objects, and query
object metadata. The same client can be used for both regular user
operations and wallet administrative actions.
All wallet actions are controlled by a fine-grained set of ACLs. Each
object has an owner ACL and optional get, store, show, destroy, and
flags ACLs that control more specific actions. A global administrative
ACL controls access to administrative actions. An ACL consists of zero
or more entries, each of which is a generic scheme and identifier pair,
allowing the ACL system to be extended to use any existing authorization
infrastructure. Currently, the only ACL type supported matches a single
Kerberos principal name, but this will be extended in future releases.
Currently, the object types supported are simple files and Kerberos
keytabs. By default, whenever a Kerberos keytab object is retrieved
from the wallet, the key is changed in the Kerberos KDC and the wallet
returns a keytab for the new key. However, a keytab object can also be
configured to preserve the existing keys when retrieved. Included in
the wallet distribution is a script that can be run via remctl on an MIT
Kerberos KDC to extract the existing key for a principal, and the wallet
system will use that interface to retrieve the current key if the
unchanging flag is set on a Kerberos keytab object for MIT Kerberos.
(Heimdal doesn't require any special support.)
REQUIREMENTS
The wallet client is written in C and builds against the C remctl
libraries. You will have to install the remctl client libraries in
order to build it. remctl can be obtained from:
http://www.eyrie.org/~eagle/software/remctl/
The wallet client will build with either MIT Kerberos or Heimdal.
The wallet server is written in Perl and requires Perl 5.6.0 or later.
It uses the Perl DBI layer to talk to a database, and therefore the DBI
module and a DBD module for the database it will use must be installed.
Currently, the server has only been tested against SQLite 3 and MySQL 5
and will probably not work fully with other database backends. Porting
is welcome.
The wallet server is intended to be run under remctld and use remctld to
do authentication. It can be ported to any other front-end, but doing
so will require writing a new version of server/wallet-backend that
translates the actions in that protocol into calls to the Wallet::Server
Perl object.
The file object support in the wallet server requires the Digest::MD5
Perl module, which comes with recent versions of Perl and is available
on CPAN for older versions.
The keytab support in the wallet server supports either Heimdal or MIT
Kerberos KDCs. The Heimdal support requires the Heimdal::Kadm5 Perl
module. The MIT Kerberos support requires the MIT Kerberos kadmin
client program be installed. In either case, wallet also requires that
the wallet server have a keytab for a principal with appropriate access
to create, modify, and delete principals from the KDC (as configured in
kadm5.acl on an MIT Kerberos KDC).
To support the unchanging flag on keytab objects with an MIT Kerberos
KDC, the Net::Remctl Perl module (shipped with remctl) must be installed
on the server and the keytab-backend script must be runnable via remctl
on the KDC. This script also requires an MIT Kerberos kadmin.local
binary that supports the -norandkey option to ktadd. This option is
included in MIT Kerberos 1.7 and later.
To support the NetDB ACL verifier (only of interest at sites using NetDB
to manage DNS), the Net::Remctl Perl module must be installed on the
server.
To run the test suite, you must have Perl 5.8 or later and the Perl DBI
module installed. You will also need a DBD module installed for the
database backend you want to use (currently, either DBD::SQLite or
DBD::mysql). The other modules are available from CPAN and may be
available as part of your OS (many Linux distributions have them as
packages, for example).
To run the full test suite, additionally all of the above software
requirements must be met. Tests requiring some bit of software that's
not installed should be skipped, but not all the permutations have been
checked. The full test suite also requires the Test::Pod Perl module
(available from CPAN), that remctld be installed and available on the
user's path or in /usr/local/sbin or /usr/sbin, that test cases can run
services on and connect to port 14373 on 127.0.0.1, and that kinit and
either kvno or kgetcred (which come with Kerberos) be installed and
available on the user's path. The full test suite also requires a local
keytab and some additional configuration.
To bootstrap from a Git checkout, or if you change the Automake files
and need to regenerate Makefile.in, you will need Automake 1.11 or
later. For bootstrap or if you change configure.ac or any of the m4
files it includes and need to regenerate configure or config.h.in, you
will need Autoconf 2.64 or later.
BUILD AND INSTALLATION
You can build and install wallet with the standard commands:
./configure
make
make install
Pass --enable-silent-rules to configure for a quieter build (similar to
the Linux kernel). Use make warnings instead of make to build with full
GCC compiler warnings (requires a relatively current version of GCC).
The last step will probably have to be done as root. Currently, this
always installs both the client and the server.
You can pass the --with-wallet-server and --with-wallet-port options to
configure to compile in a default wallet server and port. If no port is
set, the remctl default port is used. If no server is set, the server
must be specified either in krb5.conf configuration or on the wallet
command line or the client will exit with an error.
By default, wallet installs itself under /usr/local except for the
server Perl modules, which are installed into whatever default site
module path is used by your Perl installation. To change the
installation location of the files other than the Perl modules, pass the
--prefix=DIR argument to configure. To change the Perl module
installation location, you will need to run perl on Makefile.PL in the
perl subdirectory of the build tree with appropriate options and rebuild
the module after running make and before running make install.
If remctl was installed in a path not normally searched by your
compiler, you must specify its installation prefix to configure with the
--with-remctl=DIR option, or alternately set the path to the include
files and libraries separately with --with-remctl-include=DIR and
--with-remctl-lib=DIR.
Normally, configure will use krb5-config to determine the flags to use
to compile with your Kerberos libraries. If krb5-config isn't found, it
will look for the standard Kerberos libraries in locations already
searched by your compiler. If the the krb5-config script first in your
path is not the one corresponding to the Kerberos libraries you want to
use or if your Kerberos libraries and includes aren't in a location
searched by default by your compiler, you need to specify
--with-krb5=PATH and --with-gssapi=PATH:
./configure --with-krb5=/usr/pubsw --with-gssapi=/usr/pubsw
You can also individually set the paths to the include directory and the
library directory with --with-krb5-include, --with-krb5-lib,
--with-gssapi-include, and --with-gssapi-lib. You may need to do this
if Autoconf can't figure out whether to use lib, lib32, or lib64 on your
platform. Note that these settings aren't used if a krb5-config script
is found.
To specify a particular krb5-config script to use, either set the
KRB5_CONFIG environment variable or pass it to configure like:
./configure KRB5_CONFIG=/path/to/krb5-config
To not use krb5-config and force library probing even if there is a
krb5-config script on your path, set KRB5_CONFIG to a nonexistent path:
./configure KRB5_CONFIG=/nonexistent
You can build wallet in a different directory from the source if you
wish. To do this, create a new empty directory, cd to that directory,
and then give the path to configure when running configure. Everything
else should work as above.
You can pass the --enable-reduced-depends flag to configure to try to
minimize the shared library dependencies encoded in the binaries. This
omits from the link line all the libraries included solely because the
Kerberos libraries depend on them and instead links the programs only
against libraries whose APIs are called directly. This will only work
with shared Kerberos libraries and will only work on platforms where
shared libraries properly encode their own dependencies (such as Linux).
It is intended primarily for building packages for Linux distributions
to avoid encoding unnecessary shared library dependencies that make
shared library migrations more difficult. If none of the above made any
sense to you, don't bother with this flag.
TESTING
The wallet system comes with an extensive test suite which you can run
with:
make check
In order to test the client in a meaningful way and test the keytab
support in the server, however, you will need to do some preparatory
work before running the test suite. Review the files:
tests/data/README
perl/t/data/README
and follow the instructions in those files to enable the full test
suite.
The test suite also requires some additional software be installed that
isn't otherwise used by the wallet. See REQUIREMENTS above for the full
list of requirements for the test suite. The test driver attempts to
selectively skip those tests for which the necessary configuration is
not available, but this has not yet been fully tested in all of its
possible permutations.
If a test fails, you can run a single test with verbose output via:
tests/runtests -o <name-of-test>
Do this instead of running the test program directly since it will
ensure that necessary environment variables are set up.
CONFIGURATION
For the basic setup and configuration of the wallet server, see the file
docs/setup in the source distribution. You will need to set up a
database on the server (unless you're using SQLite), initialize the
database, install remctld and the wallet Perl modules, and set up
remctld to run the wallet-backend program.
Before setting up the wallet server, review the Wallet::Config
docuemntation (with man Wallet::Config or perldoc Wallet::Config).
There are many customization options, some of which must be set. You
may also need to create a Kerberos keytab for the keytab object backend
and give it appropriate ACLs, and set up keytab-backend and its remctld
configuration on your KDC if you want unchanging flag support.
The wallet client supports reading configuration settings from the
system krb5.conf file. For more information, see the CONFIGURATION
section of the wallet client man page (man wallet).
THANKS
To Roland Schemers for the original idea that kicked off this project
and for the original implementation of the leland_srvtab system, which
was its primary inspiration.
To Anton Ushakov for his prior work on Kerberos v5 synchronization and
his enhancements to kasetkey to read a key from an existing srvtab.
To Jeffrey Hutzelman for his review of the original wallet design and
multiple useful discussions about what actions and configurations the
wallet would need to support to be useful outside of Stanford.
To Huaqing Zheng, Paul Pavelko, David Hoffman, and Paul Keser for their
reviews of the wallet system design and comments on design decisions and
security models.
To Jon Robertson for the refactoring of Wallet::Kadmin, Heimdal support,
and many of the wallet server-side reports.
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