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2509 lines
88 KiB
2509 lines
88 KiB
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<body dir="ltr"> |
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<div class="container"> |
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<p class="text-center" style="margin-top: 1rem; line-height: 100%; page-break-after: avoid;"> |
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<img src="manual_html_m54d0ced8.png" id="Graphic6" class="img-responsive d-block ml-auto" width="165" height="45" alt="phpGACL Logo" /> |
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<br style="clear: right;" /><br /><br /> |
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</p> |
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<p class="text-center" style="margin-top: 1rem; line-height: 100%; page-break-after: avoid;"> |
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<span class="font4"> |
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<span class="font-weight-bold" style="font-size: x-large">Generic Access Control Lists with PHP</span> |
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</span> |
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</p> |
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<p class="western"> |
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<span class="font1">Mike Benoit <</span> |
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<span<u><a href="mailto:ipso@snappymail.ca"> |
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<span class="font1">ipso@snappymail.ca</span> |
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</a></u>.</span> |
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<span class="font1">><br />James |
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Russell <</span><a href="mailto:james-phpgacl@ps2-pro.com"> |
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<span class="font1">james-phpgacl@ps2-pro.com</span> |
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</a> |
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<span class="font1">><br />Karsten Dambekalns <</span><a href="mailto:k.dambekalns@fishfarm.de"> |
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<span class="font1">k.dambekalns@fishfarm.de</span> |
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</a> |
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<span class="font1">></span> |
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</p> |
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<p class="western"> |
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<span class="font1">Copyright © 2002-2006 Mike Benoit<br />Copyright © 2003, James Russell<br />Copyright © 2003, Karsten Dambekalns</span> |
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</p> |
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<p class="western"> |
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<span class="font1">Document Version: 60</span> |
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</p> |
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<p class="western"> |
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<span class="font1">Last Updated: <strong><sdfield TYPE="datetime" sdnum="1033;1033;MMMM D, YYYY">September 3, 2006</sdfield> - <sdfield type="datetime" sdval="37761.788287037" sdnum="1033;1033;HH:MM AM/PM">06:55 PM</sdfield></strong></span> |
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</p> |
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<h1 class="western">Table of Contents</h1> |
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<div id="Table of Contents1" class="mb-3"> |
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<p class="mt-0" style="margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Table of Contents 2</span> |
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</p> |
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<p class="mt-0" style="margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2"><a href="#about">About 4</a></span> |
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</p> |
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<p class="mt-0" style="margin-bottom: 1rem; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2"><a href="#aboutisit">What is it? 4</a></span> |
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</p> |
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<p class="mt-0" style="margin-bottom: 1rem; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2"><a href="#aboutgetit">Where can I get it? 4</a></span> |
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</p> |
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<p class="mt-0" style="margin-bottom: 1rem; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2"><a href="#aboutrunit">What do I need to run it? 4</a></span> |
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</p> |
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<p class="mt-0" style="margin-bottom: 1rem; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Who is responsible for it? 4</span> |
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</p> |
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<p class="mt-0" style="margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2"><a href="#introduction">Introduction 5</a></span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Understanding Access Control 5</span> |
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</p> |
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<p style="margin-left: 0.33in; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Who/Where 5</span> |
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</p> |
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<p style="margin-left: 0.33in; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Who/Where 6</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2"><a href="#defaccesscontrol">Defining access control with phpGACL 6</a></span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2"><a href="#finegrainacccontrol">Fine-grain access control 8</a></span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Multi-level Groups 8</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">How does phpGACL determine |
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permissions? 9</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Adding groups 10</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Adding people 11</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Resolving conflicts 11</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Naming Access Objects 12</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Adding Sections 14</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Multiple Purposes 15</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Access eXtension Objects 16</span> |
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</p> |
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<p style="margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Installation 18</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Basic setup 18</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Advanced setup 19</span> |
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</p> |
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<p style="margin-left: 0.33in; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Reusing an already existing ADOdb |
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installation 19</span> |
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</p> |
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<p class="mt-0" style="margin-left: 0.33in; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Reusing an already existing Smarty |
|
installation 20</span> |
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</p> |
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<p class="mt-0" style="margin-left: 0.33in; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">How do I move the phpGACL files out |
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of my website tree while leaving a link in the tree for |
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administration? 20</span> |
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</p> |
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<p style="margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Using phpGACL in your application 21</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Basic usage 21</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Advanced usage 21</span> |
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</p> |
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<p style="margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Using the ACL admin utility 22</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">ACL's 22</span> |
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</p> |
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<p style="margin-left: 0.33in; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Creating 22</span> |
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</p> |
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<p style="margin-left: 0.33in; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Sections 23</span> |
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</p> |
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<p style="margin-left: 0.33in; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Extended Return Value 24</span> |
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</p> |
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<p style="margin-left: 0.33in; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Notes 24</span> |
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</p> |
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<p style="margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">Glossary 25</span> |
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</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">ACO 25</span> |
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</p> |
|
<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">ARO 25</span> |
|
</p> |
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<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">AXO 25</span> |
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</p> |
|
<p style="margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">References 26</span> |
|
</p> |
|
<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">phpGACL API 26</span> |
|
</p> |
|
<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
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<span class="font2">phpGACL Examples and Tutorials 26</span> |
|
</p> |
|
<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
|
<span class="font2">Access Control Resources 26</span> |
|
</p> |
|
<p style="margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
|
<span class="font2">FAQ 27</span> |
|
</p> |
|
<p style="margin-bottom: 1rem; margin-top: 0; margin-bottom: 0.25rem; line-height: 100%"> |
|
<span class="font2">Can phpGACL handle large sets of |
|
data? 27</span> |
|
</p> |
|
</div> |
|
<h1 class="western" id="about">About</h1> |
|
<h2 class="western" id="aboutisit"><span class="font1">What is it?</span></h2> |
|
<p class="western"> |
|
<span class="font1">phpGACL |
|
is an set of functions that allows you to apply access control to |
|
arbitrary objects (web pages, databases, etc) by other arbitrary |
|
objects (users, remote hosts, etc).</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1">It offers fine-grained access control with simple management, and is very fast.</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1">It |
|
is written in PHP (hence <strong>php</strong>GACL), a popular scripting |
|
language that is commonly used to dynamically create web pages. The |
|
GACL part of phpGACL stands for Generic Access Control List.</span> |
|
</p> |
|
<h2 class="western" id="aboutgetit"><span class="font1">Where can I get it?</span></h2> |
|
<p class="western"> |
|
<span class="font1">phpGACL is hosted by sourceforge.net at </span><a href="http://phpGACL.sourceforge.net/"> |
|
<span class="font1">http://phpGACL.sourceforge.net/</span> |
|
</a> |
|
</p> |
|
<h2 class="western" id="aboutrunit"><span class="font1">What do I need to run it?</span></h2> |
|
<p class="western"> |
|
<span class="font1">phpGACL |
|
requires a relational database to store the access control |
|
information. It accesses this database via an abstract wrapper called |
|
</span><a href="http://php.weblogs.com/adodb"> |
|
<span class="font1">ADOdb</span> |
|
</a> |
|
<span class="font1">. |
|
This is compatible with databases such as PostgreSQL, MySQL and |
|
Oracle.</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1">phpGACL |
|
is written in the </span><a href="http://www.php.net/"> |
|
<span class="font1">PHP</span> |
|
</a> |
|
<span class="font1"> |
|
scripting language. It requires PHP 4.2 and above.</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1">Access |
|
Control List administration is performed by a web interface, and |
|
therefore it is necessary to have a web server with PHP support, such |
|
as </span><a href="http://httpd.apache.org/"> |
|
<span class="font1">Apache</span> |
|
</a> |
|
<span class="font1">.</span> |
|
</p> |
|
<h2 class="western"> |
|
<span class="font1">Who is responsible for it?</span> |
|
</h2> |
|
<p class="western"> |
|
<span class="font1">Mike Benoit </span><<a href="mailto:ipso@snappymail.ca"> |
|
<span class="font1">ipso@snappymail.ca</span> |
|
</a>> |
|
<span class="font1">is the author and project manager.</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1">James Russell </span><<a href="mailto:james-phpgacl@ps2-pro.com"> |
|
<span class="font1">james-phpgacl@ps2-pro.com</span></a>> |
|
<span class="font1"> and Karsten Dambekalns</span> <<a href="mailto:k.dambekalns@fishfarm.de"><span class="font1">k.dambekalns@fishfarm.de</span></a>> |
|
<span class="font1"> did the documentation.</span> |
|
</p> |
|
<h1 class="western" id="introduction">Introduction</h1> |
|
<h2 class="western"> |
|
<span class="font1">Understanding |
|
Access Control</span> |
|
</h2> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">The |
|
best way to explain access control is to use examples with real |
|
things rather than trying to relate to concepts.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Han |
|
is captain of the Millennium Falcon and Chewie is his second officer. |
|
They've taken on board some passengers: Luke, Obi-wan, R2D2 and C3PO. |
|
Han needs to define access restrictions for various rooms of the |
|
ship: The Cockpit, Lounge, Engines and the external Guns.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Han |
|
says: "Me and Chewie should have access to everywhere, but after |
|
a particularly messy hyperdrive repair, I forbid Chewie from going |
|
near the Engine Room ever again. Passengers are confined to the |
|
Passenger's Lounge."</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Let's |
|
assume from now on that access is Boolean. That is, the result of |
|
looking up a person's access to a room is either ALLOW or DENY. There |
|
is no middle ground.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span>If |
|
we mapped this statement into an </span><strong>access matrix</strong><span> |
|
showing who has access to where, it would look something like this (O |
|
means ALLOW, X means DENY):</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<dl> |
|
<dd> |
|
<table class="table" width="337" border="1" cellpadding="7" cellspacing="0"> |
|
<col width="81"> |
|
<col width="56"> |
|
<col width="44"> |
|
<col width="31"> |
|
<col width="53"> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<h3 class="western text-right"> |
|
<span class="font1">Who/Where</span> |
|
</h3> |
|
</td> |
|
<td width="56"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">Cockpit</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">Lounge</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="31"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">Guns</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="53"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">Engines</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">Han</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="56" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="31" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="53" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">Chewie</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="56" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="31" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="53" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">Obi-wan</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="56" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="31" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="53" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">Luke</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="56" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="31" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="53" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">R2-D2</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="56" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="31" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="53" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">C3PO</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="56" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="31" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="53" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
</table> |
|
</dd> |
|
</dl> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span><span>The |
|
columns list the rooms that Han wants to restrict access to, and the |
|
rows list the people that might request access to those rooms. More |
|
generally, the "rooms" are "things to control access |
|
on". We call these </span><strong>Access Control Objects</strong><span> |
|
(ACOs). The "people" are "things </span><i>requesting</i><span> |
|
access". We call these </span><strong>Access Request Objects</strong><span> |
|
(AROs). The </span><i>people</i><span> request access to |
|
the </span><i>rooms</i><span>, or in our terminology, |
|
</span><i>AROs</i><span> request access to the </span><i>ACOs</i><span>.</span></span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span>There is a third type of Object, the </span><strong>Access eXtention Object</strong><span> (AXO) that we'll discuss later. These objects share many attributes and are collectively referred to as Access Objects.</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Managing access using an access matrix like the one above has advantages and disadvantages.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small"><i>Advantages:</i></span> |
|
</span> |
|
</p> |
|
<ul> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">It's |
|
very fine-grained. It's possible to control access for an individual |
|
person if necessary.</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"><span> |
|
<span class="font-small"> |
|
It's |
|
easy to see <u>who</u>. has access to <u>what</u>.. The answer is |
|
stored in the intersection of the person and the room. |
|
</span> |
|
</span></span> |
|
</span> |
|
</p> |
|
</ul> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small"><i>Disadvantages:</i></span> |
|
</span> |
|
</p> |
|
<ul> |
|
<li value="1"> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">It's |
|
difficult to manage on a large scale. 6 passengers and 4 places is |
|
fairly simple, but what if there were thousands of passengers and |
|
hundreds of places, and you need to restrict access to large groups |
|
of them at once, but still retain enough fine-grained control to |
|
manage access for an individual? That would mean a lot of fiddly and |
|
lengthy adjustment to the matrix, and it's a difficult task to |
|
verify that the final matrix is correct.</span> |
|
</span> |
|
</p> |
|
</li> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">It's |
|
hard to summarize or visualize. The above example is fairly simple |
|
to summarize in a few sentences (as Han did above), but what if the |
|
matrix looked like this?</span> |
|
</span> |
|
</p> |
|
<table class="table" width="337" border="1" cellpadding="7" cellspacing="0"> |
|
<col width="81"> |
|
<col width="52"> |
|
<col width="44"> |
|
<col width="35"> |
|
<col width="54"> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<h3 class="western text-right"> |
|
<span class="font1">Who/Where</span> |
|
</h3> |
|
</td> |
|
<td width="52"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">Cockpit</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">Lounge</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="35"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">Guns</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="54"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">Engines</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">Han</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="52" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="35" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="54" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">Chewie</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="52" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="35" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="54" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">Obi-wan</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="52" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="35" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="54" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">Luke</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="52" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="35" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="54" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">R2-D2</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="52" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="35" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="54" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
<tr class="align-top"> |
|
<td width="81"> |
|
<p class="western text-right"> |
|
<span class="font1"> |
|
<span class="font-small">C3PO</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="52" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="44" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="35" class="bg-danger"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">×</span> |
|
</span> |
|
</p> |
|
</td> |
|
<td width="54" class="bg-success"> |
|
<p class="western text-center"> |
|
<span class="font1"> |
|
<span class="font-small">O</span> |
|
</span> |
|
</p> |
|
</td> |
|
</tr> |
|
</table> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">This |
|
matrix is not so obvious to summarize, and it's not clear to the |
|
reader why those access decisions might have been made in the first |
|
place.</span> |
|
</span> |
|
</p> |
|
</li> |
|
</ul> |
|
<h2 class="western" id="defaccesscontrol"><span class="font1">Defining access control with phpGACL</span></h2> |
|
<p class="western"> |
|
<span class="font1">It |
|
seems that for large or complex situations, this 'access matrix' |
|
approach is clearly unsuitable. We need a better system that |
|
maintains the advantages (fine-grain control and a clear idea of <u>who</u>. |
|
has access to <u>what</u>.) but removes the disadvantages (difficult |
|
to summarize, and difficult to manage large groups of people at |
|
once). One solution is phpGACL.</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"><span> |
|
<span class="font-small"> |
|
phpGACL |
|
doesn't describe access from the 'bottom-up' like the Access Matrix |
|
above. Instead, it describes it 'top-down', like the textual |
|
description of Han's access policy. This is a very flexible system |
|
that allows you to manage access in large groups, it neatly |
|
summarizes the access policy, and it's easy to see <u>who </u>.has |
|
access to <u>what</u>.. |
|
</span> |
|
</span></span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span>An |
|
</span><strong>ARO tree</strong><span> defines a hierarchy of |
|
</span><strong>Groups</strong><span> and AROs (things that request |
|
access). This is very similar to a tree view of folders and files. |
|
The 'folders' are the Groups and the 'files' are AROs.</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Let's |
|
make an ACL tree for the people on Han's ship. First we define some |
|
categories for the people. It's clear that Han and Chewie run the |
|
ship, and the rest of them are just passengers:</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font-code"> |
|
<span class="font-small">Millennium |
|
Falcon Passengers Group<br />├─Crew Group<br />│ |
|
├─Han ARO<br />│ |
|
└─Chewie ARO<br />└─Passengers Group<br /> |
|
├─Obi-wan ARO<br /> ├─Luke ARO<br /> |
|
├─R2D2 ARO<br /> └─C3PO ARO</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">This |
|
tree by itself doesn't specify any access policy; it just shows how |
|
we're grouping the people who might request access (AROs).</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1">We |
|
apply access restrictions by assigning instructions about a |
|
particular room (ACO) to Groups or AROs in the tree. Han says: "By |
|
default, no-one should be allowed access to any room on the |
|
Millennium Falcon. But the Crew should have access to every room. The |
|
Passengers should only have access to the Lounge."</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font3"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span class="font-code"> |
|
<span>Millennium |
|
Falcon Passengers<br />├─Crew </span><strong>[ALLOW: ALL]</strong><span><br />│ |
|
├─Han<br />│ └─Chewie<br />└─Passengers </span><strong>[ALLOW: |
|
Lounge]</strong><span><br /> ├─Obi-wan<br /> |
|
├─Luke<br /> ├─R2D2<br /> └─C3PO</span> |
|
</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">To interpret this ARO tree, we start from the top and work our way down.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Firstly, |
|
the default policy is always to deny access. Permissions have been |
|
overridden for the "Crew", so they have access to |
|
everywhere ("ALL" is a synonym for all rooms: "Cockpit, |
|
Lounge, Guns, Engines"). The "Passengers" have access |
|
only to the Lounge.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"><span> |
|
<span class="font-small"> |
|
This |
|
way of describing the access policy is much clearer than the access |
|
matrix. You can easily see who has access to what, and it's easier to |
|
determine <u>why</u>. they've got access (it seems obvious that Han |
|
and Chewie would have access to everything, since they're grouped |
|
under "Crew"). |
|
</span> |
|
</span></span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">To summarize:</span> |
|
</span> |
|
</p> |
|
<ul> |
|
<li value=1> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<strong>Access Control Objects </strong><span>(ACOs) are the things we want to control access to (e.g. web pages, databases, rooms, etc).</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<strong>Access |
|
Request Objects</strong><span> (AROs) are the things that |
|
request access (e.g. people, remote computers, etc)</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<strong>ARO trees</strong><span> define a hierarchy of </span><strong>Groups</strong><span> |
|
and AROs. Groups can contain other Groups and AROs.</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">The |
|
default 'catch-all' policy for the ARO tree is always "DENY |
|
ALL".</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">To |
|
assign access policy, work your way down the tree, explicitly |
|
assigning permissions to Groups and AROs for each ACO as the need |
|
arises.</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<h2 class="western" id="finegrainacccontrol"><span class="font1">Fine-grain access control</span></h2> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Oops! |
|
What about Chewie? By grouping him in "Crew", Han has |
|
indirectly given him access to the Engines! He doesn't want that |
|
after what Chewie recently did to the hyperdrive, so he adds a rule |
|
to disallow this:</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font3"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span class="font-code"> |
|
<span>Millennium |
|
Falcon Passengers<br />├─Crew [ALLOW: ALL]<br />│ |
|
├─Han<br />│ └─Chewie </span><strong>[DENY: |
|
Engines]</strong><span><br />└─Passengers [ALLOW: |
|
Lounge]<br /> ├─Obi-wan<br /> ├─Luke<br /> |
|
├─R2D2<br /> └─C3PO</span> |
|
</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">This |
|
is an example of the way you can control access policy in a |
|
fine-grained manner. It is not necessary to move Chewie to another |
|
Group; we simply over-ride the access policy at a lower level.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Another example of fine-grain control happens when the Empire attacks; Han needs to let Luke man the guns, and let R2D2 repair the hyperdrive in the Engine room. He can do this by over-riding the general permissions granted by their status as a "Passenger":</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font3"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span class="font-code"> |
|
<span>Millennium |
|
Falcon Passengers<br />├─Crew [ALLOW: ALL]<br />│ |
|
├─Han<br />│ └─Chewie [DENY: |
|
Engines]<br />└─Passengers [ALLOW: Lounge]<br /> ├─Obi-wan<br /> |
|
├─Luke </span><strong>[ALLOW: Guns]</strong><span><br /> |
|
├─R2D2 </span><strong>[ALLOW: Engines]</strong><span><br /> |
|
└─C3PO</span> |
|
</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<h2 class="western"> |
|
<span class="font1">Multi-level |
|
Groups</span> |
|
</h2> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Groups |
|
can be extended to any level in the ARO tree. For example, you could |
|
add a Group "Jedi" to "Passengers". Most |
|
passengers would be categorized under "Passengers", but |
|
Luke and Obi-wan would be under "Jedi" and therefore might |
|
be extended extra privileges (like access to the Cockpit):</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font3"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span class="font-code"> |
|
<span>Millennium |
|
Falcon Passengers<br />├─Crew [ALLOW: ALL]<br />│ |
|
├─Han<br />│ └─Chewie [DENY: |
|
Engines]<br />└─Passengers [ALLOW: Lounge]<br /> |
|
├─</span><strong>Jedi [ALLOW: Cockpit]</strong><span><br /> |
|
│ ├─</span><strong>Obi-wan</strong><span><br /> |
|
│ └─</span><strong>Luke</strong><span> [ALLOW: |
|
Guns] <br /> ├─R2D2 [ALLOW: Engines]<br /> └─C3PO</span> |
|
</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<h2 class="western"> |
|
<span class="font1">How |
|
does phpGACL determine permissions?</span> |
|
</h2> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">When |
|
the ship's computer (running phpGACL of course) checks access, the |
|
only question it can ask itself is "Does person X have access to |
|
room Y?" In phpGACL terms, this is rephrased as "Does ARO |
|
'X' have access to ACO 'Y'?"</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">phpGACL |
|
determines whether a specific person has access to a specific room by |
|
working from the top of the ARO tree towards the specified person, |
|
noting explicit access controls for that place along the way. When it |
|
reaches that person, it uses the last explicit access control it |
|
encountered as the result to return. In this way, you can define |
|
access controls for groups of people, but over-ride them further down |
|
the tree if you need to.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<strong>Example |
|
1</strong><span>: We ask: "Does Luke have access to the |
|
Lounge?".</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<ul> |
|
<li value="1"> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Set |
|
the default result, "DENY".</span> |
|
</span> |
|
</p> |
|
</li> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Work |
|
out a path to Luke:</span> |
|
</span> |
|
</p> |
|
</li> |
|
</ul> |
|
<h4 class="western"> |
|
<span class="font1"> Millennium |
|
Falcon Passengers → Passengers → Jedi → Luke</span> |
|
</h4> |
|
<ul> |
|
<li value=1> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Start |
|
at the top of the tree and move towards Luke: The "Millennium |
|
Falcon Passengers" node doesn't say anything about any room, so |
|
do nothing here.</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Move |
|
on to "Passengers", which explicitly says that |
|
"Passengers" have Lounge access, so change the internal |
|
result to "ALLOW".</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Move |
|
to the "Jedi" node, which doesn't mention the Lounge at |
|
all.</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Finally |
|
move to Luke's node, and again there's nothing there about the |
|
Lounge.</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">There's |
|
nowhere left to go, so the result returned is the current value of |
|
the internal result: "ALLOW"</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<strong>Example |
|
2</strong><span>: We ask: "Does Chewie have access to |
|
the Engines?"</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<ul> |
|
<li value=1> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Set |
|
the default result, "DENY".</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Work |
|
out a path to Chewie:</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<h4 class="western"> |
|
<span class="font1"> Millennium |
|
Falcon Passengers → Crew → Chewie</span> |
|
</h4> |
|
<ul> |
|
<li> |
|
<p class="western">Start at the top of the tree and move towards |
|
Chewie. The "Millennium Falcon Passengers" node doesn't |
|
say anything about anywhere, so do nothing here.</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Move |
|
on to "Crew", which explicitly says that "Crew" |
|
have Engine access, so change the internal result to "ALLOW".</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Move |
|
to Chewie's node, and there's an explicit rule saying that he |
|
doesn't have access to the Engines, so change the internal result to |
|
"DENY".</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">There's |
|
nowhere left to go, so the result returned is the current value of |
|
the internal result: "DENY"</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">As |
|
you can see from the examples, if a Group doesn't explicitly specify |
|
a permission for a room, then that Group inherits the access |
|
restrictions of its parent for that room. If the root node |
|
("Millennium Falcon Passengers") doesn't specify a |
|
permission, it inherits it from the default setting ("DENY ALL" |
|
in the above examples).</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">This |
|
implies a couple of interesting points about the ARO tree:</span> |
|
</span> |
|
</p> |
|
<ul> |
|
<li value=1> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">The |
|
ARO tree always shows the full list of the AROs. It would not make |
|
sense to ask "Does Jabba have access to the Cockpit?" |
|
because Jabba has not been defined in this system. However, phpGACL |
|
does not check to see if AROs or ACOs exist before performing the |
|
check, so if this question was actually asked then the result would |
|
be the default "DENY".</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">The |
|
ARO tree may not display some defined ACOs, and relies on the |
|
default setting to define access policy. For example, say Han |
|
defined a "Bathroom" ACO. Any question like "Does |
|
Luke have access to the Bathroom?" would have the answer |
|
"DENY", because the default is "DENY" and |
|
nowhere in the ARO tree does it ever explicitly mention the |
|
Bathroom. Keep in mind when examining the ARO tree that some ACOs |
|
may not be visible.</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<strong>Note:</strong><span> |
|
When asking phpGACL questions about access to an ACO, it is not |
|
possible to use Groups as AROs (even though it might 'seem' right). |
|
For example, it is impossible to answer the question "Do |
|
Passengers have access to Guns?" The complete answer is not a |
|
Boolean "ALLOW" or "DENY", but the more complex |
|
"Luke and Obi-wan can but R2D2 and C3PO cannot." phpGACL is |
|
not designed to return that kind of answer.</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<h2 class="western"> |
|
<span class="font1">Adding |
|
groups</span> |
|
</h2> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Han |
|
feels this ACL is starting to look a little complicated. There are so |
|
many exceptions! Perhaps he should make another group, "Engineers", |
|
containing the people who are allowed access to the Engines and Guns. |
|
That group should contain Han and R2D2 since they're both capable of |
|
repairing the engines and guns. This means Han can remove some of |
|
those messy exceptions-to-the-rules, and that has the benefit of |
|
making the description clearer:</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font-code">Default: DENY |
|
ALL<br />Millennium Falcon Passengers<br />├─Crew [ALLOW: |
|
ALL]<br />│ ├─Han<br />│ └─Chewie [DENY: |
|
Engines]<br />├─Passengers [ALLOW: Lounge]<br />│ |
|
├─Jedi [ALLOW: Cockpit]<br />│ │ ├─Obi-wan<br />│ |
|
│ └─Luke [ALLOW: Guns] <br />│ ├─R2D2<br />│ |
|
└─C3PO<br />└─<strong>Engineers [ALLOW: Engines, |
|
Guns]</strong><br /> ├─<strong>Han</strong><br /> └─<strong>R2D2</strong></span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">We |
|
can read this as "By default, no-one has access to anywhere. |
|
Crew have access to everywhere (except Chewie, who has no access to |
|
the Engines). Passengers only have access to the Lounge, except Jedi |
|
who also have access to the Cockpit. Luke has access to the Guns too. |
|
Engineers are allowed access to the Engines and Guns."</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span>Most |
|
importantly, we can see that Han and R2D2 are now in </span><i>two</i><span> |
|
places in the ACL. It is not necessary for them to be uniquely |
|
categorized at all. This defines the policy more clearly to the |
|
reader: "Ahh, Han and R2D2 have access to the Engines and Guns |
|
because they're </span><i>engineers</i><span>."</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<h2 class="western"> |
|
<span class="font1">Adding |
|
people</span> |
|
</h2> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">Han |
|
goes to Cloud City to pick up Lando and get some repairs. Lando's the |
|
Millennium Falcon's previous owner, so Han reckons he qualifies as |
|
Crew. Lando also offers the services of his top engineer, Hontook, |
|
for help with repairing the ship while they're in dock.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font-code">Default: DENY |
|
ALL<br />Millennium Falcon Passengers<br />├─Crew [ALLOW: |
|
ALL]<br />│ ├─Han<br />│ ├─Chewie [DENY: |
|
Engines]<br />│ └─<strong>Lando</strong><br />├─Passengers [ALLOW: |
|
Lounge]<br />│ ├─Jedi [ALLOW: Cockpit]<br />│ │ |
|
├─Obi-wan<br />│ │ └─Luke [ALLOW: |
|
Guns] <br />│ ├─R2D2<br />│ |
|
└─C3PO<br />└─Engineers [ALLOW: Engines, |
|
Guns]<br /> ├─Han<br /> ├─R2D2<br /> └─<strong>Hontook</strong></span> |
|
</p> |
|
<p class="western"> |
|
<span class="font1"> |
|
<span class="font-small">This |
|
shows how easy it is to grant new people access. If we used the |
|
original matrix scheme, we'd have to set permissions for each room |
|
for both Lando and Hontook. Instead, we simply add them to their |
|
appropriate groups and their access is implicitly and easily defined.</span> |
|
</span> |
|
</p> |
|
<h2 class="western"> |
|
<span class="font1">Resolving |
|
conflicts</span> |
|
</h2> |
|
<p class="western"> |
|
<span class="font1">What |
|
happens if we add Chewie to the list of Engineers?</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font-code">Default: DENY |
|
ALL<br />Millennium Falcon Passengers<br />├─Crew [ALLOW: |
|
ALL]<br />│ ├─Han<br />│ ├─Chewie [DENY: |
|
Engines]<br />│ └─Lando<br />├─Passengers [ALLOW: |
|
Lounge]<br />│ ├─Jedi [ALLOW: Cockpit]<br />│ │ |
|
├─Obi-wan<br />│ │ └─Luke [ALLOW: |
|
Guns] <br />│ ├─R2D2<br />│ |
|
└─C3PO<br />└─Engineers [ALLOW: Engines, |
|
Guns]<br /> ├─Han<br /> ├─R2D2<br /> ├─Hontook<br /> |
|
└─<strong>Chewie</strong></span> |
|
</p> |
|
<p class="western">This makes Chewie's access to the Engines |
|
ambiguous, because now there are two paths from the root of the tree |
|
to Chewie. If the ship's computer follows one path (along the "Crew" |
|
branch), the result is "DENY access to Engines." If it |
|
follows the other path (along the "Engineers" branch) then |
|
the result is "ALLOW access to Engines". So, is he allowed |
|
or denied?</p> |
|
<p class="western">phpGACL will warn you if you add or edit an |
|
multiply-grouped ARO in such a way that the ARO's access to an |
|
arbitrary ACO would be ambiguous. But it is <u>up to you</u>. to |
|
resolve the conflict.</p> |
|
<p class="western">If we now asked phpGACL the question "Does |
|
Chewie have access to Engines?" the result returned is the |
|
result given by the <u>last ACL entry to be modified</u>. (this is |
|
phpGACL's policy). In this case the result is ALLOW, because the |
|
"ALLOW: Engines, Guns" directive assigned to the Engineers |
|
Group is more recent than the "DENY: Engines" directive |
|
assigned to Chewie's Group.</p> |
|
<p class="western">When ambiguous access entries exist in the ACL, |
|
the ACL is said to be <strong>inconsistent</strong>. Inconsistent ACLs can be |
|
very dangerous, and you may unwittingly provide access to |
|
inappropriate people if you allow your ACL to remain in this state. |
|
When phpGACL warns you that the ACL is inconsistent, it is best to |
|
resolve the conflicts as soon as possible to regain consistency.</p> |
|
<p class="western">To resolve the conflict in this case, we could |
|
either:</p> |
|
<ul> |
|
<li value=1> |
|
<p class="western">Remove the "DENY: Engines" |
|
directive from Chewie's entry under the Crew Group.</p> |
|
<li> |
|
<p class="western">Add a "DENY: Engines" directive to |
|
Chewie's entry under the Engineers Group.</p> |
|
<li> |
|
<p class="western">Remove Chewie from the Engineers Group, since |
|
Han doesn't think him a worthy Engineer anyway.</p> |
|
</ul> |
|
<p class="western">Han chooses option 3, and removes Chewie from the |
|
Engineers list.</p> |
|
<h2 class="western">Naming Access Objects</h2> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">phpGACL |
|
uniquely identifies each Access Object (AROs, AXOs and ACOs) with a |
|
two-keyword combination and it's Access Object type.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">The |
|
tuple "(Access Object type, Section, Value)" uniquely |
|
identifies any Access Object.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">The |
|
first element of the tuple is the type of Access Object (ARO, AXO or |
|
ACO).</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font3"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span class="font5"> |
|
<span>The |
|
second element of the tuple, called the </span><strong>Section</strong><span>, |
|
is a user-defined string which names the general category of the |
|
Access Object. Multiple Access Objects can share the same Section |
|
name. The Section name should be short but descriptive. It's used in |
|
the user interface in selection boxes, so try not to make it too |
|
long.</span> |
|
</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">Sections |
|
are stored in a flat namespace; they are not nestable like Groups. |
|
Sections have nothing to do with Groups or the ARO/AXO trees - they |
|
are purely a mechanism for helping to maintain large numbers of |
|
Access Objects.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font3"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span class="font5"> |
|
<span>The |
|
third element of the tuple is a user-defined name for the Access |
|
Object, and is called the </span><strong>Value</strong><span>. <u>A |
|
Value cannot contain spaces</u>. (however, a Section can).</span> |
|
</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small"><u>Both |
|
Section and Values are case sensitive.</u>.</span> |
|
</span> |
|
</p> |
|
<p class="western" style="margin-left: 0.38in; margin-top: 0; margin-bottom: 0in; line-height: 1rem"> |
|
<span class="font3"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span class="font5"><strong>Aside:</strong><span> |
|
It is commonly asked why strings are used to identify Access Objects, |
|
rather than integers which ostensibly seem faster. The answer is for |
|
legibility. It is much easier to understand:<br /> </span></span><span> |
|
<span class="font-code-2">acl_check('system', |
|
'login', 'users', 'john_doe');<br /></span> |
|
<span class="font5">than:</span> |
|
<span class="font-code-2"><br /> acl_check(10, |
|
21004, 15, 20304);</span> |
|
</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font3"> |
|
<span style="font-size: 3"> |
|
<span class="font-small"> |
|
<span class="font5"> |
|
<span>Since |
|
it is often obvious from the context which type of Access Object we |
|
are referring to, the interface for phpGACL (and this documentation) |
|
drops the Access Object type and uses the format "</span><strong>Section |
|
> Value</strong><span>" when displaying the name of |
|
an Access Object. However, the API requires an Access Object's |
|
"Section" and "Value" to be specified in separate |
|
function arguments (the Access Object type is usually implicit in the |
|
argument description).</span> |
|
</span> |
|
</span> |
|
</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small"><strong>Example |
|
ACO "Section > Values":</strong></span> |
|
</span> |
|
</p> |
|
<ul> |
|
<li value=1> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">"Floors |
|
> 1st"</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">"Floors |
|
> 2nd"</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">"Rooms |
|
> Engines"</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<p class="western font-weight-bold">Example ARO "Section > Values":</p> |
|
<ul> |
|
<li value=1> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">"People |
|
> John_Smith”</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western">“<span class="font5"> |
|
<span class="font-small">People |
|
> Cathy_Jones”</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western">“<span class="font5"> |
|
<span class="font-small">Hosts |
|
> sandbox.something.com”</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<p class="western"><strong>Example API usage:</strong></p> |
|
<ul> |
|
<li value=1> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">acl_check ( |
|
aco_section, aco_value, aro_section, aro_value);</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">acl_check ( |
|
'Floors', '2nd', 'People', 'John_Smith' );</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small"><strong>Valid |
|
Naming Restrictions Examples:</strong></span> |
|
</span> |
|
</p> |
|
<ul> |
|
<li value=1> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">"ACO |
|
-Frob > Flerg", "ARO - Frob > Flerg" (The |
|
Section and Value are the same in both, but this is fine as |
|
namespaces are separate across Access Object types)</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">"ACO |
|
-Frob > Flerg", "ACO - Frob > Queegle" (The |
|
Access Object type and Section are the same, but this is fine as the |
|
Values are different)</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">"AXO |
|
- Frob Hrung > Flerg" (Sections can contain spaces)</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small"><strong>Invalid |
|
Naming Restrictions Examples:</strong></span> |
|
</span> |
|
</p> |
|
<ul> |
|
<li value=1> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">"ACO |
|
- Frob > Flerg", "ACO - Frob > Flerg" ("Access |
|
Object type - Section > Value" must be unique)</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">"ACO |
|
- Frob > Flerg Habit" (Values cannot contain spaces)</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<h2 class="western">Adding Sections</h2> |
|
<p style="line-height: 100%"> |
|
<span class="font5">Before |
|
you can add a new Access Object, its Section must be defined. To add |
|
a new section, use the add_object_section() function.</span> |
|
</p> |
|
<p class="western" style="line-height: 100%"> |
|
<span class="font2"> |
|
<span class="font-small">add_object_section |
|
(</span> |
|
</span> |
|
</p> |
|
<p style="margin-left: 2.5in; text-indent: -2in; line-height: 100%"> |
|
<span class="font2"> |
|
<span class="font-code">string |
|
name,</span> A short description of what this Section is for. (e.g. |
|
"Levels in building"). |
|
</span> |
|
</p> |
|
<p style="margin-left: 2.5in; text-indent: -2in; line-height: 100%"> |
|
<span class="font2"> |
|
<span class="font-code">string |
|
value,</span> The name of the Section (e.g. "Floor"). |
|
</span> |
|
</p> |
|
<p style="margin-left: 2.5in; text-indent: -2in; line-height: 100%"> |
|
<span class="font2"> |
|
<span class="font-code">int ORDER,</span> An arbitrary value which affects the order this Section appears in the UI. |
|
</span> |
|
</p> |
|
<p style="margin-left: 2.5in; text-indent: -2in; line-height: 100%"> |
|
<span class="font2"> |
|
<span class="font-code">bool HIDDEN, </span>Whether this should appear in the UI or not (TRUE means that is will be hidden). |
|
</span> |
|
</p> |
|
<p style="margin-left: 2.5in; text-indent: -2in; line-height: 100%"> |
|
<span class="font2"> |
|
<span class="font-code">string GROUP_TYPE) </span>The Access Object type ("aco", "aro" or "axo")</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">Han |
|
creates 3 Sections for the AROs. "Humans", "Aliens" |
|
and "Androids". Let's list the AROs with their full names</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font-code">Millennium |
|
Falcon Passengers<br />├─Crew [ALLOW: ALL]<br />│ |
|
├─<strong>"Humans > Han"</strong><br />│ ├─<strong>"Aliens |
|
> Chewie"</strong> [DENY: Engines]<br />│ └─<strong>"Humans |
|
> Lando"</strong><br />├─Passengers [ALLOW: Lounge]<br />│ |
|
├─Jedi [ALLOW: Cockpit]<br />│ │ ├─<strong>"Humans |
|
> Obi-wan"</strong><br />│ │ └─<strong>"Humans |
|
> Luke"</strong> [ALLOW: Guns] <br />│ ├─<strong>"Androids |
|
> R2D2"</strong><br />│ └─<strong>"Androids > |
|
C3PO"</strong><br />└─Engineers [ALLOW: Engines, Guns]<br /> |
|
├─<strong>"Humans > Han"</strong><br /> ├─<strong>"Androids |
|
> R2D2"</strong><br /> └─<strong>"Aliens > Hontook"</strong></span> |
|
</p> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">Sections |
|
are just a way of categorizing Access Objects, to make the user |
|
interface more usable, and the code for acl_check() more readable. |
|
They do not affect the way phpGACL determines access to an object. |
|
They cannot be nested (so it would not be able to create a "Males" |
|
sub-Section under "Humans" for example; you'd have to |
|
create a Section called "Humans-Male" or similar)</span> |
|
</span> |
|
</p> |
|
<h2 class="western">Multiple Purposes</h2> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">You may need to use phpGACL for multiple independent purposes. For example, you may need to restrict user access to web pages, and also remote host access to your server. The two tasks are not related.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">phpGACL can handle this in three different ways.</span> |
|
</span> |
|
</p> |
|
<ul> |
|
<li value=1> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">It can use an alternative database to store the access tables.</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">It can use the same database but with differently named access tables. (this feature is not implemented yet).</span> |
|
</span> |
|
</p> |
|
<li> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">You can store the Access Objects for both purposes in the same tables, and carefully manage your list so that they don't conflict.</span> |
|
</span> |
|
</p> |
|
</ul> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">To |
|
implement Option 1 (and Option 2 when it becomes available), use the |
|
$gacl_options array when creating a new phpGACL class. This allows |
|
you to specify the database and table name prefixes to use:</span> |
|
</span> |
|
</p> |
|
<p class="western my-0"> |
|
<span class="font-code-2"> |
|
<span class="font-small">$gacl_options |
|
= array(<br /> 'db_table_prefix' => 'gacl_',<br /> 'db_type' => |
|
'mysql',<br /> 'db_host' => 'host1',<br /> 'db_user' => |
|
'user',<br /> 'db_password' => 'passwd',<br /> 'db_name' => |
|
'gacl');</span> |
|
</span> |
|
</p> |
|
<p class="western my-0"> |
|
<br /> |
|
</p> |
|
<p class="western my-0"> |
|
<span class="font-code-2"> |
|
<span class="font-small">$gacl_host1 = new gacl($gacl_options);</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">To |
|
implement Option 3, you must be careful, since phpGACL doesn't know |
|
the relationship between your different tasks, and it will be |
|
possible to make meaningless Access Policy Directives.</span> |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small">For |
|
example, say Han wanted to restrict access to other ships contacting |
|
his ship's computer, in addition to restricting access to the |
|
different rooms. To do this, he might add "Luke's X-Wing |
|
Fighter" as a remote ship ARO (in addition to other ships and an |
|
ACO for the ship's computer). Because all AROs are in the same ARO |
|
tree, it would be possible to create an APD like "Ships > |
|
Luke's X-Wing Fighter" [ALLOW: "Rooms > Lounge"], |
|
which would be totally meaningless! To help reduce mistakes like |
|
this, good Section naming can make it clearer what Access Objects are |
|
for which tasks. It should be obvious to any administrator that it's |
|
meaningless to assign a Ship permission to use a Room.</span> |
|
</span> |
|
</p> |
|
<h2 class="western">Access eXtension Objects</h2> |
|
<p class="western"><strong>Access eXtension Objects</strong> (AXOs) can add a |
|
3rd dimension to the permissions that can be configured in phpGACL. |
|
We've seen how phpGACL allows you to combine an ARO and an ACO (2 |
|
dimensions) to create an Access Policy Directive. This is great for |
|
simple permission requests like:</p> |
|
<p class="western"> Luke (ARO) requests access to "Guns" |
|
(ACO)</p> |
|
<p class="western">If that's all you need, that's fine - AXOs are |
|
totally optional.</p> |
|
<p class="western">But because all ACOs are considered equal, it |
|
makes it difficult to manage if there are many ACOs. If this is the |
|
case, we can change the way we look at Access Objects to manage it |
|
more easily.</p> |
|
<p class="western">AXOs are identical to AROs in many respects. There |
|
is an AXO tree (separate from the ARO tree), with it's own Groups and |
|
AXOs. When dealing with AXOs, consider an AXO to take the old role of |
|
the ACO (i.e. "things to control access on"), and change |
|
the view of ACOs from "things to control access on" to |
|
"actions that are requested".</p> |
|
<p class="western"><strong>ARO and ACO-only View:</strong></p> |
|
<ul> |
|
<li value=1> |
|
<p class="western">AROs: Things requesting access</p> |
|
<li> |
|
<p class="western">ACOs: Things to control access on</p> |
|
</ul> |
|
<p class="western"><strong>ARO, ACO and AXO View:</strong></p> |
|
<ul> |
|
<li value=1> |
|
<p class="western">AROs: Things requesting access</p> |
|
<li> |
|
<p class="western">ACOs: Actions that are requested</p> |
|
<li> |
|
<p class="western">AXOs: Things to control access on</p> |
|
</ul> |
|
<p class="western"><strong>Example:</strong></p> |
|
<p class="western">A website manager is trying to manage access to |
|
projects on the website. The ARO tree consists of all the users:</p> |
|
<p class="western"> |
|
<span class="font-code">Website<br />├─Administrators<br />│ |
|
├─Alice<br />│ └─Carol<br />└─Users<br /> |
|
├─Bob<br /> └─Alan</span> |
|
</p> |
|
<p class="western">The projects are organized by Operating System |
|
into categories in the AXO tree:</p> |
|
<p class="western"> |
|
<span class="font-code">Projects<br />├─Linux<br />│ |
|
├─SpamFilter2<br />│ └─AutoLinusWorshipper<br />└─Windows<br /> |
|
├─PaperclipKiller<br /> └─PopupStopper</span> |
|
</p> |
|
<p class="western">The actions that can be taken with each project |
|
are "View" and "Edit". These are the ACOs.</p> |
|
<p class="western">Now we want Bob to have "View" access to |
|
all the Linux projects, so it's possible to add an ACL that links |
|
Bob's ARO to the View ACO and the Linux AXO, and thus we can ask the |
|
question:</p> |
|
<p class="western"> Bob (ARO) requests access to "View" |
|
(ACO) the project(s) called "Linux" (AXO)</p> |
|
<p class="western">Keep in mind AXO's are optional, if you don't |
|
specify an AXO when calling acl_check() and a matching ACL exists |
|
with no AXO, it will be allowed. However if <u>only</u>. ACLs exist |
|
with AXO's, and you call acl_check() without an AXO, it will fail.</p> |
|
<p class="western">So basically as soon as you specify an AXO when |
|
calling acl_check(), acl_check() will only search ACLs containing |
|
AXO's. If no AXO is specified, only ACLs without AXOs are searched. |
|
This in theory (I haven't benchmarked) gives us a slight performance |
|
increase as well.</p> |
|
<h1 class="western">Installation</h1> |
|
<h2 class="western">Basic setup</h2> |
|
<OL> |
|
<li> |
|
<p class="western">Untar the distribution .tar.gz file into the |
|
root or a subdirectory of your web site. You might want to rename it |
|
to something more suitable.<br /><br /><br /> |
|
</p> |
|
<p class="western"><iMG SRC="manual_html_m48c2db5c.png" name="Graphic1" class="img-responsive" width="474" height="146" /><br style="clear: left;" /></p> |
|
<li> |
|
<p class="western">Edit phpgacl/gacl.ini.php using your |
|
favourite editor and set the db_type, db_host, db_user, db_password, |
|
and db_name you will be using.</p> |
|
<li> |
|
<p class="western">Create the database you specified in db_name |
|
on the server.<br /><br /><br /> |
|
</p> |
|
<p class="western"><img src="manual_html_m770a5a15.png" name="Graphic3" class="img-responsive" width="397" height="123"><br style="clear: left;" /></p> |
|
<p class="western"></p> |
|
<li> |
|
<p class="western">Surf to |
|
http://yoursite.net/phpgacl/setup.php. The required tables will be |
|
installed based on your choice of database. Don't be afraid of the |
|
truckload of output, if all goes well you will see only success |
|
messages.<br /><br /><br /> |
|
</p> |
|
</OL> |
|
<p class="western"><img src="manual_html_7dced6ce.png" name="Graphic4" class="img-responsive" width="519" height="504" /><br style="clear: left;" /><br /><br /> |
|
</p> |
|
<OL START=5> |
|
<li> |
|
<p class="western">Now follow the last advice shown on that |
|
screen and create the phpgacl/admin/smarty/templates_c directory. It |
|
must be writable by the user the webserver runs as. If you don't do |
|
this, you will not be able to use the CAL admin!</p> |
|
<li> |
|
<p class="western">Click the link at the bottom of the |
|
successful setup page or surf |
|
to:<br />http://yoursite.net/phpgacl/admin/acl_admin.php</p> |
|
</OL> |
|
<h2 class="western">Advanced setup</h2> |
|
<h3 class="western">Reusing an already existing ADOdb |
|
installation</h3> |
|
<p class="western">If you already have ADOdb installed you can get |
|
phpGACL to use this copy of ADOdb.</p> |
|
<OL> |
|
<li> |
|
<p class="western">Edit phpgacl/gacl.class.php so that ADODB_DIR |
|
reflects the location of the ADOdb library in your path.</p> |
|
<li> |
|
<p class="western">Rename the phpgacl/adodb folder to something |
|
else like adodb_x and reload the phpgacl/admin/acl_admin.php page to |
|
ensure it still works.</p> |
|
<li> |
|
<p class="western">Erase the adodb directory installed with |
|
phpGACL.</p> |
|
</OL> |
|
<h3 class="western">Reusing an already existing Smarty |
|
installation</h3> |
|
<p class="western">If you already have ADOdb installed you can get |
|
phpGACL to use this copy of ADOdb.</p> |
|
<OL> |
|
<li> |
|
<p class="western">Edit phpgacl/admin/gacl_admin.inc.php so that |
|
the variables $smarty_dir and $smarty_compile_dir reflect the |
|
location of the Smarty library in your path and the template_c |
|
directory you already use.</p> |
|
<p class="western">Move the templates directory that came with |
|
phpGACL to another directory (e.g. one level up). Adjust the |
|
$smarty_template_dir so it points to the new location. If you like |
|
you can move those templates to your existing templates folder, of |
|
course.</p> |
|
<li> |
|
<p class="western">Rename the phpgacl/smarty folder to something |
|
else like smarty_x and reload the phpgacl/admin/acl_admin.php page |
|
to ensure it still works.</p> |
|
<li> |
|
<p class="western">Erase the smarty directory installed with |
|
phpGACL.</p> |
|
</OL> |
|
<h3 class="western">How do I move the phpGACL files out |
|
of my website tree while leaving a link in the tree for |
|
administration?</h3> |
|
<OL> |
|
<li> |
|
<p class="western">Go to your website root.</p> |
|
<li> |
|
<p class="western">Move the phpGACL directory to your includes |
|
directory and create a symlink to the admin directory where you want |
|
the admin tool to go. For example:</p> |
|
<p class="western">mv phpgacl/ /www/includes_directory<br />ln -s |
|
/www/includes_directory/phpgacl/admin/ gacl</p> |
|
<li> |
|
<p class="western">Now surfing to |
|
http://yoursite.net/gacl/acl_admin.php will take you to the admin |
|
page. If it doesn't work, make sure your Webserver allows symbolic |
|
links in the website tree.</p> |
|
</OL> |
|
<h1 class="western">Using phpGACL in your application</h1> |
|
<h2 class="western">Basic usage</h2> |
|
<p class="western">This example shows a basic example of using |
|
phpGACL in your code. It uses the ADOdb abstraction layer as well, |
|
and shows a simple way to validate a login attempt against a |
|
database.</p> |
|
<p class="western"> |
|
<span class="font6"> |
|
<span style="color: #ff0000">// |
|
include basic ACL api</span><br /> |
|
<span style="color: #00cccc">include</span>('<span style="color: #008000">phpgacl/gacl.class.php</span>');<br />$<span style="color: #ff6633">gacl</span> |
|
= <span style="color: #00cccc">new</span> gacl(); |
|
</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font6">$<span style="color: #ff6633">username</span> |
|
= $<span style="color: #ff6633">db</span>-><span style="color: #00cccc">quote</span>($<span style="color: #ff6633">_POST</span>['<span style="color: #008000">username</span>']);<br />$<span style="color: #ff6633">password</span> |
|
= $<span style="color: #ff6633">db</span>-><span style="color: #00cccc">quote</span>(md5($<span style="color: #ff6633">_POST</span>['<span style="color: #008000">password</span>']));<br />$<span style="color: #ff6633">sql</span> |
|
= '<span style="color: #008000">SELECT name FROM users WHERE name=</span>';<br />$<span style="color: #ff6633">sql</span> |
|
.= $<span style="color: #ff6633">username</span>.' <span style="color: #008000">AND |
|
password=</span>'.$<span style="color: #ff6633">password</span>;<br />$<span style="color: #ff6633">row</span> |
|
= $<span style="color: #ff6633">db</span>-><span style="color: #00cccc">GetRow</span>($<span style="color: #ff6633">sql</span>);</span> |
|
</p> |
|
<p class="western"> |
|
<span class="font6"> |
|
<span style="color: #00cccc">if</span>($<span style="color: #ff6633">gacl</span>-><span style="color: #00cccc">acl_check</span>('<span style="color: #008000">system</span>','<span style="color: #008000">login</span>','<span style="color: #008000">user</span>',$<span |
|
color="#ff6633">row</span>['<span style="color: #008000">name</span>'])){<br /> |
|
$<span style="color: #ff6633">_SESSION</span>['<span style="color: #008000">username</span>'] |
|
= $<span style="color: #ff6633">row</span>['<span style="color: #008000">name</span>'];<br /> |
|
<span style="color: #00cccc">return</span> |
|
<span style="color: #6b4794">true</span>;<br />}<br /> |
|
<span style="color: #00cccc">else</span><br /> |
|
<span style="color: #00cccc">return</span> |
|
<span style="color: #6b4794">false</span>; |
|
</span> |
|
</p> |
|
<p class="western">As you can see there is only one call to |
|
acl_check() in this code. What does it do? Well, it</p> |
|
<ul> |
|
<li> |
|
<p class="western">checks the ARO object $row['name'] from the |
|
ARO section 'user'</p> |
|
<li> |
|
<p class="western">against the ACO object 'login' from the ACO |
|
section 'system'.</p> |
|
</ul> |
|
<h2 class="western">Advanced usage</h2> |
|
<p class="western"><br /><br /> |
|
</p> |
|
<h1 class="western">Using the ACL admin utility</h1> |
|
<p class="western">If you want to get a grip on the included ACL |
|
admin utitlity, it will help you a lot if you run the example.php |
|
file. It contains some ACO, ARO and AXO objects, as well as some ACL |
|
defined using those objects. After running it, you should see some |
|
sample data in the admin interface.<br /><br /><br /> |
|
</p> |
|
<p class="western"><img src="manual_html_4b803670.png" name="Graphic5" class="img-responsive" width="531" height="488" /><br style="clear: left;" /><br /><br /> |
|
</p> |
|
<p class="western">Play around with it, and if you get stuck, come |
|
back and read on...</p> |
|
<p class="western">(yet to be written)</p> |
|
<h2 class="western">ACL's</h2> |
|
<h3 class="western">Creating</h3> |
|
<p class="western">You must have a minimum of an ACO and an ARO |
|
defined to create an ACL.</p> |
|
<p class="western">Select an ACO Section then select from the |
|
available items show in the Access Control Objects list. Click the [ |
|
> > ] button to add the Section-ACO to the Selected list. You |
|
may add any number of Section-ACO pairs to this list.</p> |
|
<p class="western"><img src="manual_html_m608b392a.png" name="Graphic9" class="img-responsive" width="531" height="177" /><br style="clear: left;" /><br /><br /> |
|
</p> |
|
<p class="western">Next select an ARO Section. At this point you may |
|
select from either the Access Request Objects list or from the ARO |
|
Groups list.</p> |
|
<p class="western"><img SRC="manual_html_157037e7.png" name="Graphic10" class="img-responsive" width="531" height="157" /><br style="clear: left;" /><br /><br /> |
|
</p> |
|
<p class="western">Select on of the ACL Sections (usually “user” |
|
for this case), provide a brief description in the Note area and then |
|
click Submit. Click on the “ACL Admin” tab and you will |
|
see your new ACL in the list.</p> |
|
<h3 class="western">Sections</h3> |
|
<p class="western"><img src="manual_html_676f8c98.png" name="Graphic7" class="img-responsive" width="518" height="149" /><br style="clear: left;" />A |
|
default install provides you with two ACL sections – 'system' |
|
and 'user'. You would typically put user created ACL's (for example, |
|
those you enter via the admin interface) in the 'user' section and |
|
put ACL's generated by code in the 'system' section. However, you |
|
can use the ACL sections to provide any other logical grouping that |
|
suits your purposes.</p> |
|
<h3 class="western">Extended Return Value</h3> |
|
<p class="western">Typically a call to the acl_check method will |
|
return a boolean value. However, you may specify a different value |
|
or evan a string to be returned. |
|
</p> |
|
<p class="western">For example, you may negotiate for a user to login |
|
at a cost of $0.20 per time by default and another for $0.18 per time |
|
under a different scheme. You could create a separate ACL for the |
|
default login and for the special use but varying the 'return value'. |
|
If the call to acl_check is successful, you will know the cost of |
|
the login via the return value.</p> |
|
<h3 class="western">Notes</h3> |
|
<p class="western">It's a good idea to add a note when creating an |
|
ACL to help remember it's purpose, for example “Basic |
|
permissions for a user in the Administrator group”.</p> |
|
<p class="western"><img src="manual_html_m4f4324cb.png" name="Graphic8" class="img-responsive" width="526" height="120" /><br style="clear: left;" /><br /><br /> |
|
</p> |
|
<h1 class="western"><a name="Glossary"></a>Glossary</h1> |
|
<h2 class="western">ACO</h2> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small"><dfn>Access Control Object – An action that are requested to be performed.</dfn></span> |
|
</span> |
|
</p> |
|
<h2 class="western">ARO</h2> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small"><dfn><span> |
|
<span class="font-small"> |
|
<span class="font5">Access Request Object – An entity (for example, a user) that is requesting an action to be performed.</span> |
|
</span> |
|
</span></dfn></span> |
|
</span> |
|
</p> |
|
<h2 class="western">AXO</h2> |
|
<p class="western"> |
|
<span class="font5"> |
|
<span class="font-small"><dfn><span> |
|
<span class="font-small"> |
|
<span class="font5"> |
|
Access eXtension Object – An object to perform an action on for an entity.</span> |
|
</span> |
|
</span></dfn></span> |
|
</span> |
|
</p> |
|
<h1 class="western">References</h1> |
|
<h2 class="western">phpGACL API</h2> |
|
<p class="western" style="line-height: 100%"> |
|
<span class="font5"> |
|
<span class="font-small">The API documentation is included in the tarball under the /docs/phpdoc/ directory.</span> |
|
</span> |
|
</p> |
|
<h2 class="western">phpGACL Examples and Tutorials</h2> |
|
<p class="western" style="line-height: 100%"> |
|
<span class="font5"> |
|
<span class="font-small">See example.php included in the tarball.</span> |
|
</span> |
|
</p> |
|
<h2 class="western">Access Control Resources</h2> |
|
<p class="western" style="line-height: 100%"> |
|
<span class="font5"> |
|
<span class="font-small">. . .</span> |
|
</span> |
|
</p> |
|
<p class="western"><br /><br /> |
|
</p> |
|
<h1 class="western">FAQ</h1> |
|
<h2 class="western">Can phpGACL handle large sets of data?</h2> |
|
<p class="western" style="line-height: 100%"> |
|
<span class="font5"> |
|
<span class="font-small">Not a problem at all. We've tested up to 100,000 AXO's and 100,000 ARO's on moderate hardware even. The performance issues come down to how well you can cache the ACL's, and how fast your database server is.</span> |
|
</span> |
|
</p> |
|
</div> |
|
</body> |
|
|
|
</html>
|
|
|