Import CUPS v2.0rc1

[thirdparty/cups.git] / cups / api-filter.shtml

diff --git a/cups/api-filter.shtml b/cups/api-filter.shtml
index 4b8372eddad88110de830d8e1a9a983eb0f73483..7c33179c8ea1962587fb28dab96fa9876e48b559 100644 (file)
--- a/cups/api-filter.shtml
+++ b/cups/api-filter.shtml
@@ -3,7 +3,7 @@
 
   Filter and backend programming introduction for CUPS.
 
-  Copyright 2007-2013 by Apple Inc.
+  Copyright 2007-2014 by Apple Inc.
   Copyright 1997-2006 by Easy Software Products, all rights reserved.
 
   These coded instructions, statements, and computer programs are the
@@ -81,7 +81,7 @@ directory to write to.</p>
 
 <p>In addition, some operating systems provide additional security mechanisms
 that further limit file system access, even for backends running as root. On
-OS X, for example, no backend may write to a user's home directory.</p>
+OS X, for example, no backend may write to a user's home directory. See the <a href="#SANDBOXING">Sandboxing on OS X</a> section for more information.</p>
 </blockquote>
 
 <h3><a name="SIGNALS">Canceled Jobs and Signal Handling</a></h3>
@@ -852,3 +852,25 @@ void *my_data;
 
 <a href="#cupsSideChannelSNMPWalk">cupsSNMPSideChannelWalk</a>(".1.3.6.1.2.1.43", 5.0, my_callback, my_data);
 </pre>
+
+<h2><a name="SANDBOXING">Sandboxing on OS X</a></h2>
+
+<p>Starting with OS X 10.6, filters and backends are run inside a security "sandbox" which further limits (beyond the normal UNIX user/group permissions) what a filter or backend can do. This helps to both secure the printing system from malicious software and enforce the functional separation of components in the CUPS filter chain. What follows is a list of actions that are explicitly allowed for all filters and backends:</p>
+
+<ol>
+
+       <li>Reading of files: pursuant to normal UNIX file permissions, filters and backends can read files for the current job from the <var>/private/var/spool/cups</var> directory and other files on mounted filesystems <em>except</em> for user home directories under <var>/Users</var>.</li>
+
+       <li>Writing of files: pursuant to normal UNIX file permissions, filters and backends can read/write files to the cache directory specified by the <code>CUPS_CACHEDIR</code> environment variable, to the state directory specified by the <code>CUPS_STATEDIR</code> environment variable, to the temporary directory specified by the <code>TMPDIR</code> environment variable, and under the <var>/private/var/db</var>, <var>/private/var/folders</var>, <var>/private/var/lib</var>, <var>/private/var/mysql</var>, <var>/private/var/run</var>, <var>/private/var/spool</var> (except <var>/private/var/spool/cups</var>), <var>/Library/Application&nbsp;Support</var>, <var>/Library/Caches</var>, <var>/Library/Logs</var>, <var>/Library/Preferences</var>, <var>/Library/WebServer</var>, and <var>/Users/Shared</var> directories.</li>
+
+       <li>Execution of programs: pursuant to normal UNIX file permissions, filters and backends can execute any program not located under the <var>/Users</var> directory. Child processes inherit the sandbox and are subject to the same restrictions as the parent.</li>
+
+       <li>Bluetooth and USB: backends can access Bluetooth and USB printers through IOKit. <em>Filters cannot access Bluetooth and USB printers directly.</em></li>
+
+       <li>Network: filters and backends can access UNIX domain sockets under the <var>/private/tmp</var>, <var>/private/var/run</var>, and <var>/private/var/tmp</var> directories. Backends can also create IPv4 and IPv6 TCP (outgoing) and UDP (incoming and outgoing) socket, and bind to local source ports. <em>Filters cannot directly create IPv4 and IPv6 TCP or UDP sockets.</em></li>
+
+       <li>Notifications: filters and backends can send notifications via the Darwin <code>notify_post()</code> API.</li>
+
+</ol>
+
+<blockquote><b>Note:</b> The sandbox profile used in CUPS 2.0 still allows some actions that are not listed above - these privileges will be removed over time until the profile matches the list above.</blockquote>