NAME

Lemonldap::NG::Handler - The Apache module part of Lemonldap::NG Web-SSO system.

SYNOPSIS

Create your Apache module

Create your own package (example using a central configuration database):

  package My::Package;
  use Lemonldap::NG::Handler::SharedConf::DBI;
  @ISA = qw(Lemonldap::NG::Handler::SharedConf::DBI);
  
  __PACKAGE__->init ( {
    # Local storage used for sessions and configuration
    localStorage        => "Cache::DBFile",
    localStorageOptions => {...},
    # How to get my configuration
    dbiChain            => "DBI:mysql:database=$database;host=$hostname;port=$port",
    dbiUser             => "lemonldap",
    dbiassword          => "password",
    # Maximum time to load a local stored configuration
    reloadTime          => 1200, # Default: 600
  } );

Configure Apache

Call your package in /apache-dir/conf/httpd.conf:

  # Load your package
  PerlRequire /My/File
  # TOTAL PROTECTION
  PerlInitHandler My::Package
  # OR SELECTED AREA
  <Location /protected-area>
    PerlInitHandler My::Package
  </Location>

The configuration is loaded only at Apache start. Create an URI to force configuration reload, so you don't need to restart Apache at each change:

  # /apache-dir/conf/httpd.conf
  <Location /location/that/I/ve/choosed>
    Order deny,allow
    Deny from all
    Allow from my.manager.com
    PerlInitHandler My::Package->refresh
  </Location>

DESCRIPTION

Lemonldap::NG is a modular Web-SSO based on Apache::Session modules. It simplifies the build of a protected area with a few changes in the application.

It manages both authentication and authorization and provides headers for accounting. So you can have a full AAA protection for your web space as described below.

The Apache module part works both with Apache 1 and 2 ie mod_perl 1 and 2 but not with mod_perl 1.99.

Authentication, Autorization, Accounting

Authentication

If a user isn't authenticated and attemps to connect to an area protected by a Lemonldap::NG compatible handler, he is redirected to a portal. The portal authenticates user with a ldap bind by default, but you can also use another authentication sheme like using x509 user certificates (see Lemonldap::NG::Portal::AuthSSL for more).

Lemonldap use session cookies generated by Apache::Session so as secure as a 128-bit random cookie. You may use the securedCookie options of Lemonldap::NG::Portal to avoid session hijacking.

You have to manage life of sessions by yourself since Lemonldap knows nothing about the Apache::Session module you've choosed, but it's very easy using a simple cron script because Lemonldap::NG::Portal stores the start time in the _utime field. By default, a session stay 10 minutes in the local storage, so in the worth case, a user is authorized 10 minutes after he lost his rights.

Authorization

Authorization is controled only by handlers because the portal knows nothing about the way the user will choose. When configuring your Web-SSO, you have to:

  • choose the ldap attributes you want to use to manage accounting and authorization (see exportedHeaders parameter in Lemonldap::NG::Portal documentation).

  • create Perl expression to define user groups (using ldap attributes)

  • create an array foreach virtual host associating URI regular expressions and Perl expressions to use to grant access.

Example

Exported variables (in Lemonldap::NG::Portal, will be stored in configuration database):

  exportedVars => {
      cn            => "cn",
      departmentUID => "departmentUID",
      login         => "uid",
  },

User groups (stored in configuration database with Lemonldap::NG::Manager):

  groups => {
      group1 => '{ $departmentUID eq "unit1" or $login = "xavier.guimard" }',
      ...
  },

Area protection (stored in configuration database with Lemonldap::NG::Manager):

  locationRules => {
      www1.domain.com => {
          '^/protected/.*$' => '$groups =~ /\bgroup1\b/',
          default           => 'accept',
      },
      www2.domain.com => {
          '^/site/.*$' => '$uid eq "xavier.guimard" or $groups =~ /\bgroup2\b/',
          '^/(js|css)' => 'accept',
          default      => 'deny',
      },
  },

Performance

You can use Perl expressions as complicated as you want and you can use all the exported LDAP attributes (and create your own attributes: see examples in Lemonldap::NG::Portal distribution) both in groups evaluations and area protections (you just have to call them with a "$").

You have to be careful when choosing your expressions:

  • groups are evaluated each time a user is redirected to the portal,

  • locationRules are evaluated for each request.

It is also recommanded to use the groups mechanism to avoid having to evaluate a long expression at each HTTP request:

  locationRules => {
      www1.domain.com => {
          '^/protected/.*$' => '$groups =~ /\bgroup1\b/',
      },
  },

You can also use ldap filters in groups parameter, or Perl expression or mixed expressions. Perl expressions has to be enclosed with {}:

  • group1 => '(|(uid=xavier.guimard)(ou=unit1))'

  • group1 => '{$uid eq "xavier.guimard" or $ou eq "unit1"}'

  • group1 => '(|(uid=xavier.guimard){$ou eq "unit1"})'

It is also recommanded to use Perl expressions to avoid requiering the LDAP server more than 2 times per authentication.

Accounting

Logging portal access

Lemonldap::NG::Portal doesn't log anything by default, but it's easy to overload log method for normal portal access or using error method to know what was wrong if process method has failed.

Logging application access

Because an handler knows nothing about the protected application, it can't do more than logging URL. As Apache does this fine, Lemonldap::NG::Handler gives it the name to used in logs. The whatToTrace parameters indicates which variable Apache has to use ($uid by default).

The real accounting has to be done by the application itself which knows the result of SQL transaction for example.

Lemonldap can export http headers either using a proxy or protecting directly the application. By default, the User-Auth field is used but you can change it using the exportedHeaders parameters (stored in the configuration database). This parameters contains an associative array:

  • keys are the names of the choosen headers

  • values are perl expressions where you can use user datas stored in the global store by calling them $<varname>.

Example:

  exportedHeaders => {
      www1.domain.com => {
          'Auth-User' => '$uid',
          'Unit'      => '$ou',
      },
      www2.domain.com => {
          'Authorization' => '"Basic ".encode_base64($employeeNumber.":dummy")',
      },
  }

Storage systems

Lemonldap::NG use 3 levels of cache for authenticated users:

  • an Apache::Session::* module choosed with the globalStorage parameter (completed with globalStorageOptions) and used by lemonldap::NG::Portal to store authenticated user parameters,

  • a Cache::Cache module choosed with the localStorage parameter (completed with localStorageOptions and used to share authenticated users between Apache's threads or processus and of course between virtual hosts,

  • Lemonldap::NG variables: if the same user use the same thread or processus a second time, no request are needed to grant or refuse access. This is very efficient with HTTP/1.1 Keep-Alive system.

So the number of request to the central storage is limited to 1 per user each 10 minutes.

Lemonldap::NG is very fast, but you can increase performance using a Cache::Cache module that does not use disk access.

USING LEMONLDAP::NG::HANDLER FOR DEVELOPMENT

Lemonldap::NG::Handler provides different modules:

All those modules are compatible both with Apache and mod_perl version 1 and 2, but NOT with mod_perl 1.99. If you use Linux distributions like Debian Sarge who provide mod_perl 1.99 for Apache2, you have to use Apache-1.3 or to download a mod_perl2 backport.

SEE ALSO

Lemonldap::NG::Handler::SharedConf::DBI, Lemonldap::NG::Portal, Lemonldap::NG::Manager

AUTHOR

Xavier Guimard, <x.guimard@free.fr>

COPYRIGHT AND LICENSE

Copyright (C) 2005 by Xavier Guimard <x.guimard@free.fr>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.4 or, at your option, any later version of Perl 5 you may have available.

Lemonldap was originaly written by Eric German who decided to publish him in 2003 under the terms of the GNU General Public License version 2. Lemonldap::NG is a complete rewrite of Lemonldap and is able to have different policies in a same Apache virtual host.