<title>suEXEC Support - Apache HTTP Server</title>
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-<p class="apache">Apache HTTP Server Version 2.3</p>
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+<p class="apache">Apache HTTP Server Version 2.5</p>
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-<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="./">Version 2.
3</a></div><div id="page-content"><div id="preamble"><h1>suEXEC Support</h1>
+<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="./">Version 2.
5</a></div><div id="page-content"><div id="preamble"><h1>suEXEC Support</h1>
<div class="toplang">
<p><span>Available Languages: </span><a href="./en/suexec.html" title="English"> en </a> |
+<a href="./fr/suexec.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
<a href="./ja/suexec.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
-<a href="./ko/suexec.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
+<a href="./ko/suexec.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> |
+<a href="./tr/suexec.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
</div>
- <p>The <strong>suEXEC</strong> feature provides
- Apache users the ability
+ <p>The <strong>suEXEC</strong> feature provides users of the Apache
+ HTTP Server the ability
to run <strong>CGI</strong> and <strong>SSI</strong> programs
under user IDs different from the user ID of the calling
web server. Normally, when a CGI or SSI program executes, it
<li><img alt="" src="./images/down.gif" /> <a href="#debug">Debugging suEXEC</a></li>
<li><img alt="" src="./images/down.gif" /> <a href="#jabberwock">Beware the Jabberwock:
Warnings & Examples</a></li>
-</ul></div>
+</ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
<div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
<div class="section">
<h2><a name="before" id="before">Before we begin</a></h2>
<p>Before jumping head-first into this document,
- you should be aware of the assumptions made on the part of the
- Apache Group and this document.</p>
+ you should be aware that certain assumptions are made about you and
+ the environment in which you will be using suexec.</p>
<p>First, it is assumed that you are using a UNIX
derivative operating system that is capable of
security risks. It is <strong>highly</strong> recommended you
not alter the suEXEC code unless you are well versed in the
particulars of security programming and are willing to share
- your work with the Apache Group for consideration.</p>
+ your work with the Apache HTTP Server development team for consideration.</p>
<p>Fourth, and last, it has been the decision of
- the Apache Group to <strong>NOT</strong> make suEXEC part of
- the default installation of Apache. To this end, suEXEC
+ the Apache HTTP Server development team to <strong>NOT</strong> make suEXEC part of
+ the default installation of Apache httpd. To this end, suEXEC
configuration requires of the administrator careful attention
to details. After due consideration has been given to the
various settings for suEXEC, the administrator may install
these settings need to be carefully determined and specified by
the administrator to properly maintain system security during
the use of suEXEC functionality. It is through this detailed
- process that the Apache Group hopes to limit suEXEC
+ process that we hope to limit suEXEC
installation only to those who are careful and determined
enough to use it.</p>
taken to ensure your system's security.</p>
<p><strong>suEXEC</strong> is based on a setuid
- "wrapper" program that is called by the main Apache web server.
+ "wrapper" program that is called by the main Apache HTTP Server.
This wrapper is called when an HTTP request is made for a CGI
or SSI program that the administrator has designated to run as
a userid other than that of the main server. When such a
- request is made, Apache provides the suEXEC wrapper with the
+ request is made, Apache httpd provides the suEXEC wrapper with the
program's name and the user and group IDs under which the
program is to execute.</p>
<ol>
<li>
<strong>Is the user executing this wrapper a valid user of
- this system?</strong>
+ this system?</strong>
<p class="indent">
This is to ensure that the user executing the wrapper is
<li>
<strong>Was the wrapper called with the proper number of
- arguments?</strong>
+ arguments?</strong>
<p class="indent">
The wrapper will only execute if it is given the proper
number of arguments. The proper argument format is known
- to the Apache web server. If the wrapper is not receiving
+ to the Apache HTTP Server. If the wrapper is not receiving
the proper number of arguments, it is either being
hacked, or there is something wrong with the suEXEC
- portion of your Apache binary.
+ portion of your Apache httpd binary.
</p>
</li>
<li>
<strong>Is this valid user allowed to run the
- wrapper?</strong>
+ wrapper?</strong>
<p class="indent">
Is this user the user allowed to run this wrapper? Only
<li>
<strong>Does the target CGI or SSI program have an unsafe
- hierarchical reference?</strong>
+ hierarchical reference?</strong>
<p class="indent">
Does the target CGI or SSI program's path contain a leading
</li>
<li>
- <strong>Is the target user name valid?</strong>
+ <strong>Is the target user name valid?</strong>
<p class="indent">
Does the target user exist?
</li>
<li>
- <strong>Is the target group name valid?</strong>
+ <strong>Is the target group name valid?</strong>
<p class="indent">
Does the target group exist?
<p class="indent">
- Presently, suEXEC does not allow <code><em>root</em></code>
+ suEXEC does not allow <code><em>root</em></code>
to execute CGI/SSI programs.
</p>
</li>
<li>
<strong>Is the target userid <em>ABOVE</em> the minimum ID
- number?</strong>
+ number?</strong>
<p class="indent">
The minimum user ID number is specified during
<li>
<strong>Is the target group <em>NOT</em> the superuser
- group?</strong>
+ group?</strong>
<p class="indent">
Presently, suEXEC does not allow the <code><em>root</em></code>
<li>
<strong>Is the target groupid <em>ABOVE</em> the minimum ID
- number?</strong>
+ number?</strong>
<p class="indent">
The minimum group ID number is specified during
<li>
<strong>Can the wrapper successfully become the target user
- and group?</strong>
+ and group?</strong>
<p class="indent">
Here is where the program becomes the target user and
<p class="indent">
If it doesn't exist, it can't very well contain files. If we
- can't change directory to it, it might aswell not exist.
+ can't change directory to it, it might as well not exist.
</p>
</li>
<li>
- <strong>Is the directory within the Apache
- webspace?</strong>
+ <strong>Is the directory within the httpd webspace?</strong>
<p class="indent">
If the request is for a regular portion of the server, is
the requested directory within suEXEC's document root? If
- the request is for a UserDir, is the requested directory
+ the request is for a <code class="directive"><a href="./mod/mod_userdir.html#userdir">UserDir</a></code>, is the requested directory
within the directory configured as suEXEC's userdir (see
<a href="#install">suEXEC's configuration options</a>)?
</p>
<li>
<strong>Is the directory <em>NOT</em> writable by anyone
- else?</strong>
+ else?</strong>
<p class="indent">
We don't want to open up the directory to others; only
</li>
<li>
- <strong>Does the target CGI/SSI program exist?</strong>
+ <strong>Does the target CGI/SSI program exist?</strong>
<p class="indent">
If it doesn't exists, it can't very well be executed.
<li>
<strong>Is the target CGI/SSI program <em>NOT</em> writable
- by anyone else?</strong>
+ by anyone else?</strong>
<p class="indent">
We don't want to give anyone other than the owner the
<li>
<strong>Is the target CGI/SSI program <em>NOT</em> setuid or
- setgid?</strong>
+ setgid?</strong>
<p class="indent">
We do not want to execute programs that will then change
<li>
<strong>Is the target user/group the same as the program's
- user/group?</strong>
+ user/group?</strong>
<p class="indent">
Is the user the owner of the file?
<li>
<strong>Can we successfully clean the process environment
- to ensure safe operations?</strong>
+ to ensure safe operations?</strong>
<p class="indent">
suEXEC cleans the process' environment by establishing a
<li>
<strong>Can we successfully become the target CGI/SSI program
- and execute?</strong>
+ and execute?</strong>
<p class="indent">
Here is where suEXEC ends and the target CGI/SSI program begins.
<dt><code>--with-suexec-caller=<em>UID</em></code></dt>
<dd>The <a href="mod/mpm_common.html#user">username</a> under which
- Apache normally runs. This is the only user allowed to
- execute this program.</dd>
+ httpd normally runs. This is the only user allowed to
+ execute the suEXEC wrapper.</dd>
<dt><code>--with-suexec-userdir=<em>DIR</em></code></dt>
directories where suEXEC access should be allowed. All
executables under this directory will be executable by suEXEC
as the user so they should be "safe" programs. If you are
- using a "simple" UserDir directive (ie. one without a "*" in
- it) this should be set to the same value. suEXEC will not
- work properly in cases where the UserDir directive points to
+ using a "simple" <code class="directive"><a href="./mod/mod_userdir.html#userdir">UserDir</a></code>
+ directive (ie. one without a "*" in it) this should be set to the same
+ value. suEXEC will not work properly in cases where the <code class="directive"><a href="./mod/mod_userdir.html#userdir">UserDir</a></code> directive points to
a location that is not the same as the user's home directory
- as referenced in the passwd file. Default value is
- "public_html".<br />
- If you have virtual hosts with a different UserDir for each,
+ as referenced in the <code>passwd</code> file. Default value is
+ "<code>public_html</code>".<br />
+ If you have virtual hosts with a different <code class="directive"><a href="./mod/mod_userdir.html#userdir">UserDir</a></code> for each,
you will need to define them to all reside in one parent
directory; then name that parent directory here. <strong>If
this is not defined properly, "~userdir" cgi requests will
<dt><code>--with-suexec-docroot=<em>DIR</em></code></dt>
- <dd>Define as the DocumentRoot set for Apache. This will be
- the only hierarchy (aside from UserDirs) that can be used for
- suEXEC behavior. The default directory is the <code>--datadir</code>
- value with the suffix "/htdocs", <em>e.g.</em> if you configure
- with "<code>--datadir=/home/apache</code>" the directory
- "/home/apache/htdocs" is used as document root for the suEXEC
- wrapper.</dd>
+ <dd>Define as the DocumentRoot set for httpd. This will be
+ the only hierarchy (aside from <code class="directive"><a href="./mod/mod_userdir.html#userdir">UserDir</a></code>s) that can be used for suEXEC behavior. The
+ default directory is the <code>--datadir</code> value with the suffix
+ "<code>/htdocs</code>", <em>e.g.</em> if you configure with
+ "<code>--datadir=/home/apache</code>" the directory
+ "<code>/home/apache/htdocs</code>" is used as document root for the
+ suEXEC wrapper.</dd>
<dt><code>--with-suexec-uidmin=<em>UID</em></code></dt>
<dd>This defines the filename to which all suEXEC
transactions and errors are logged (useful for auditing and
debugging purposes). By default the logfile is named
- "suexec_log" and located in your standard logfile directory
- (<code>--logfiledir</code>).</dd>
+ "<code>suexec_log</code>" and located in your standard logfile
+ directory (<code>--logfiledir</code>).</dd>
<dt><code>--with-suexec-safepath=<em>PATH</em></code></dt>
<dd>Define a safe PATH environment to pass to CGI
executables. Default value is
- "/usr/local/bin:/usr/bin:/bin".</dd>
+ "<code>/usr/local/bin:/usr/bin:/bin</code>".</dd>
</dl>
- <p><strong>Compiling and installing the suEXEC
- wrapper</strong><br />
- If you have enabled the suEXEC feature with the
- <code>--enable-suexec</code> option the <code>suexec</code> binary
- (together with Apache itself) is automatically built if you execute
- the <code>make</code> command.<br />
- After all components have been built you can execute the
- command <code>make install</code> to install them. The binary image
- <code>suexec</code> is installed in the directory defined by the
- <code>--sbindir</code> option. The default location is
- "/usr/local/apache2/sbin/suexec".<br />
- Please note that you need <strong><em>root
- privileges</em></strong> for the installation step. In order
- for the wrapper to set the user ID, it must be installed as
- owner <code><em>root</em></code> and must have the setuserid
- execution bit set for file modes.</p>
-
- <p><strong>Setting paranoid permissions</strong><br />
- Although the suEXEC wrapper will check to ensure that its
- caller is the correct user as specified with the
- <code>--with-suexec-caller</code> <code class="program"><a href="./programs/configure.html">configure</a></code>
- option, there is
- always the possibility that a system or library call suEXEC uses
- before this check may be exploitable on your system. To counter
- this, and because it is best-practise in general, you should use
- filesystem permissions to ensure that only the group Apache
- runs as may execute suEXEC.</p>
-
- <p>If for example, your web server is configured to run as:</p>
-
-<div class="example"><p><code>
- User www<br />
- Group webgroup<br />
-</code></p></div>
-
- <p>and <code class="program"><a href="./programs/suexec.html">suexec</a></code> is installed at
- "/usr/local/apache2/sbin/suexec", you should run:</p>
-
-<div class="example"><p><code>
- chgrp webgroup /usr/local/apache2/bin/suexec<br />
- chmod 4750 /usr/local/apache2/bin/suexec<br />
-</code></p></div>
-
- <p>This will ensure that only the group Apache runs as can even
- execute the suEXEC wrapper.</p>
+ <h3>Compiling and installing the suEXEC wrapper</h3>
+
+
+ <p>If you have enabled the suEXEC feature with the
+ <code>--enable-suexec</code> option the <code>suexec</code> binary
+ (together with httpd itself) is automatically built if you execute
+ the <code>make</code> command.</p>
+
+ <p>After all components have been built you can execute the
+ command <code>make install</code> to install them. The binary image
+ <code>suexec</code> is installed in the directory defined by the
+ <code>--sbindir</code> option. The default location is
+ "/usr/local/apache2/bin/suexec".</p>
+
+ <p>Please note that you need <strong><em>root
+ privileges</em></strong> for the installation step. In order
+ for the wrapper to set the user ID, it must be installed as
+ owner <code><em>root</em></code> and must have the setuserid
+ execution bit set for file modes.</p>
+
+
+ <h3>Setting paranoid permissions</h3>
+
+
+ <p>Although the suEXEC wrapper will check to ensure that its
+ caller is the correct user as specified with the
+ <code>--with-suexec-caller</code> <code class="program"><a href="./programs/configure.html">configure</a></code>
+ option, there is
+ always the possibility that a system or library call suEXEC uses
+ before this check may be exploitable on your system. To counter
+ this, and because it is best-practise in general, you should use
+ filesystem permissions to ensure that only the group httpd
+ runs as may execute suEXEC.</p>
+
+ <p>If for example, your web server is configured to run as:</p>
+
+ <pre class="prettyprint lang-config">
+User www
+Group webgroup
+ </pre>
+
+
+ <p>and <code class="program"><a href="./programs/suexec.html">suexec</a></code> is installed at
+ "/usr/local/apache2/bin/suexec", you should run:</p>
+
+ <div class="example"><p><code>
+ chgrp webgroup /usr/local/apache2/bin/suexec<br />
+ chmod 4750 /usr/local/apache2/bin/suexec<br />
+ </code></p></div>
+
+ <p>This will ensure that only the group httpd runs as can even
+ execute the suEXEC wrapper.</p>
+
</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
<div class="section">
<h2><a name="enable" id="enable">Enabling & Disabling
suEXEC</a></h2>
- <p>Upon startup of Apache, it looks for the file
+ <p>Upon startup of httpd, it looks for the file
<code class="program"><a href="./programs/suexec.html">suexec</a></code> in the directory defined by the
<code>--sbindir</code> option (default is
- "/usr/local/apache/sbin/suexec"). If Apache finds a properly
+ "/usr/local/apache/sbin/suexec"). If httpd finds a properly
configured suEXEC wrapper, it will print the following message
to the error log:</p>
it, or the executable is not installed <em>setuid root</em>.</p>
<p>If you want to enable the suEXEC mechanism for the first time
- and an Apache server is already running you must kill and
- restart Apache. Restarting it with a simple HUP or USR1 signal
+ and an Apache HTTP Server is already running you must kill and
+ restart httpd. Restarting it with a simple HUP or USR1 signal
will not be enough. </p>
<p>If you want to disable suEXEC you should kill and restart
-
Apache after you have removed the <code class="program"><a href="./programs/suexec.html">suexec</a></code> file.</p>
+
httpd after you have removed the <code class="program"><a href="./programs/suexec.html">suexec</a></code> file.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
<div class="section">
<h2><a name="usage" id="usage">Using suEXEC</a></h2>
<p><strong>NOTE!</strong> This section may not be
complete. For the latest revision of this section of the
- documentation, see the
Apache Group's <a href="http://httpd.apache.org/docs/trunk/suexec.html">Online
+ documentation, see the <a href="http://httpd.apache.org/docs/trunk/suexec.html">Online
Documentation</a> version.</p>
<p>There are a few points of interest regarding
<li><strong>suEXEC Points Of Interest</strong></li>
<li>
- Hierarchy limitations
+ Hierarchy limitations
<p class="indent">
For security and efficiency reasons, all suEXEC requests
virtual host requests, or one top-level personal document
root for userdir requests. For example, if you have four
VirtualHosts configured, you would need to structure all
- of your VHosts' document roots off of one main Apache
+ of your VHosts' document roots off of one main httpd
document hierarchy to take advantage of suEXEC for
VirtualHosts. (Example forthcoming.)
</p>
</li>
<li>
- suEXEC's PATH environment variable
+ suEXEC's PATH environment variable
<p class="indent">
This can be a dangerous thing to change. Make certain
</li>
<li>
- Altering the suEXEC code
+ Altering the suEXEC code
<p class="indent">
Again, this can cause <strong>Big Trouble</strong> if you
</div></div>
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