Commit 1f599711 authored by Randy Terbush's avatar Randy Terbush
Browse files

Update suexec docs. 

Reviewed by: Ken Coar, Randy Terbush
Submitted by: Jason Dour


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@78245 13f79535-47bb-0310-9956-ffa450edef68
parent 2d0f29c0

docs/manual/suexec.html

+451 −136
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">

<html><head>

<HTML>

<title>Apache SetUserID Support</title>

<HEAD>

</head>

<TITLE>Apache suEXEC Support</TITLE>



</HEAD>

<!-- Background white, links blue (unvisited), navy (visited), red (active) -->

<!-- Background white, links blue (unvisited), navy (visited), red (active) -->

<BODY

<BODY

 BGCOLOR="#FFFFFF"

 BGCOLOR="#FFFFFF"
@@ -12,35 +12,272 @@ 
 ALINK="#FF0000"

 ALINK="#FF0000"

>

>

<!--#include virtual="header.html" -->

<!--#include virtual="header.html" -->

<h1 ALIGN="CENTER">Apache suEXEC Support</h1>





<H1 ALIGN="CENTER">Apache suEXEC Support</H1>

<hr>





<P ALIGN="LEFT">

<h3>What is suEXEC?</h3>

<OL>

The <STRONG>suEXEC</STRONG> feature, introduced in Apache 1.2 provides

	<LH><BIG><STRONG>CONTENTS</STRONG></BIG></LH>

the ability to run <STRONG>CGI</STRONG> programs under user IDs

	<LI><A HREF="#what">What is suEXEC?</A></LI>

different from the user ID of the calling web-server. Used properly,

	<LI><A HREF="#before">Before we begin.</A></LI>

this feature can reduce considerably the insecurity of allowing users to

	<LI><A HREF="#model">suEXEC Security Model.</A></LI>

run CGI programs. At the same time, improperly configured, this facility

	<LI><A HREF="#install">Configuring & Installing suEXEC</A></LI>

can crash your computer, burn your house down and steal all the money

	<LI><A HREF="#enable">Enabling & Disabling suEXEC</A></LI>

from your retirement fund. <STRONG>:-)</STRONG> If you aren't familiar

	<LI><A HREF="#debug">Debugging suEXEC</A></LI>

with managing setuid root programs and the security issues they

	<LI><A HREF="#jabberwock">Beware the Jabberwock: Warnings & Examples</A></LI>

present, we highly recommend that you not consider using this feature.<p>

</OL>



</P>

<hr>





<H3><A NAME="what">What is suEXEC?</A></H3>

<h3>Enabling suEXEC Support</h3>

<P ALIGN="LEFT">

Having said all that, enabling this feature is purposefully difficult with

The <STRONG>suEXEC</STRONG> feature -- introduced in Apache 1.2 -- provides

the intent that it will only be installed by users determined to use it and

Apache users the ability to run <STRONG>CGI</STRONG> and <STRONG>SSI</STRONG>

is not part of the normal install/compile process.<p>

programs under user IDs different from the user ID of the calling web-server.



Normally, when a CGI or SSI program executes, it runs as the same user who is

<h3>Configuring the suEXEC wrapper</h3>

running the web server.

From the top-level of the Apache source tree,

</P>

type:&nbsp;&nbsp;<STRONG><code>cd support [ENTER]</code></STRONG><p>



<P ALIGN="LEFT">

Used properly, this feature can reduce considerably the security risks involved

with allowing users to develop and run private CGI or SSI programs.  However,

if suEXEC is improperly configured, it can cause any number of problems and

possibly create new holes in your computer's security.  If you aren't familiar

with managing setuid root programs and the security issues they present, we 

highly recommend that you not consider using suEXEC.

</P> 



<P ALIGN="CENTER">

<STRONG><A HREF="suexec.html">BACK TO CONTENTS</A></STRONG>

</P>



<H3><A NAME="before">Before we begin.</A></H3>

<P ALIGN="LEFT">

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>



<P ALIGN="LEFT">

First, it is assumed that you are using a UNIX derivate operating system that

is capable of <STRONG>setuid</STRONG> and <STRONG>setgid</STRONG> operations.

All command examples are given in this regard.  Other platforms, if they are

capable of supporting suEXEC, may differ in their configuration.

</P>



<P ALIGN="LEFT">

Second, it is assumed you are familiar with some basic concepts of your 

computer's security and its administration.  This involves an understanding

of <STRONG>setuid/setgid</STRONG> operations and the various effects they

may have on your system and its level of security.

</P>



<P ALIGN="LEFT">

Third, it is assumed that you are using an <STRONG>unmodified</STRONG>

version of suEXEC code.  All code for suEXEC has been carefully scrutinized and

tested by the developers as well as numerous beta testers.  Every precaution has

been taken to ensure a simple yet solidly safe base of code.  Altering this

code can cause unexpected problems and new 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>



<P ALIGN="LEFT">

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 configuration is a manual process requiring of the

administrator careful attention to details.  It is through this process

that the Apache Group hopes to limit suEXEC installation only to those

who are determined to use it.

</P>



<P ALIGN="LEFT">

Still with us?  Yes?  Good.  Let's move on!

</P>



<P ALIGN="CENTER">

<STRONG><A HREF="suexec.html">BACK TO CONTENTS</A></STRONG>

</P>



<H3><A NAME="model">suEXEC Security Model</A></H3>

<P ALIGN="LEFT">

Before we begin configuring and installing suEXEC, we will first discuss

the security model you are about to implement.  By doing so, you may

better understand what exactly is going on inside suEXEC and what precautions

are taken to ensure your system's security.

</P>



<P ALIGN="LEFT">

<STRONG>suEXEC</STRONG> is based on a setuid "wrapper" program that is

called by the main Apache web 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 program's name and the 

user and group IDs under which the program is to execute.

</P>



<P ALIGN="LEFT">

The wrapper then employs the following process to determine success or

failure -- if any one of these conditions fail, the program logs the failure

and exits with an error, otherwise it will continue:

	<OL>

	<LI><STRONG>Was the wrapper called with the proper number of arguments?</STRONG>

	<BLOCKQUOTE>

	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 the proper number of arguments, it is either being hacked, or

	there is something wrong with the suEXEC portion of your Apache binary.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the user executing this wrapper a valid user of this system?</STRONG>

	<BLOCKQUOTE>

	This is to ensure that the user executing the wrapper is truly a user of the system.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is this valid user allowed to run the wrapper?</STRONG>

	<BLOCKQUOTE>

	Is this user the user allowed to run this wrapper?  Only one user (the Apache

	user) is allowed to execute this program.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Does the target program have an unsafe hierarchical reference?</STRONG>

	<BLOCKQUOTE>

	Does the target program contain a leading '/' or have a '..' backreference?  These

	are not allowed; the target program must reside within the Apache webspace.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the target user name valid?</STRONG>

	<BLOCKQUOTE>

	Does the target user exist?

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the target group name valid?</STRONG>

	<BLOCKQUOTE>

	Does the target group exist?

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the target user <EM>NOT</EM> superuser?</STRONG>

	<BLOCKQUOTE>

	Presently, suEXEC does not allow 'root' to execute CGI/SSI programs.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the target userid <EM>ABOVE</EM> the minimum ID number?</STRONG>

	<BLOCKQUOTE>

	The minimum user ID number is specified during configuration.  This allows you

	to set the lowest possible userid that will be allowed to execute CGI/SSI programs.

	This is useful to block out "system" accounts.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the target group <EM>NOT</EM> the superuser group?</STRONG>

	<BLOCKQUOTE>

	Presently, suEXEC does not allow the 'root' group to execute CGI/SSI programs.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the target groupid <EM>ABOVE</EM> the minimum ID number?</STRONG>

	<BLOCKQUOTE>

	The minimum group ID number is specified during configuration.  This allows you

	to set the lowest possible groupid that will be allowed to execute CGI/SSI programs.

	This is useful to block out "system" groups.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Can the wrapper successfully become the target user and group?</STRONG>

	<BLOCKQUOTE>

	Here is where the program becomes the target user and group via setuid and setgid

	calls.  The group access list is also initialized with all of the groups of which

	the user is a member.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Does the directory in which the program resides exist?</STRONG>

	<BLOCKQUOTE>

	If it doesn't exist, it can't very well contain files.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the directory within the Apache webspace?</STRONG>

	<BLOCKQUOTE>

	If the request is for a regular portion of the server, is the requested directory

	within the server's document root?  If the request is for a UserDir, is the requested

	directory within the user's document root?

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the directory <EM>NOT</EM> writable by anyone else?</STRONG>

	<BLOCKQUOTE>

	We don't want to open up the directory to others; only the owner user may be able

	to alter this directories contents.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Does the target program exist?</STRONG>

	<BLOCKQUOTE>

	If it doesn't exists, it can't very well be executed.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the target program <EM>NOT</EM> writable by anyone else?</STRONG>

	<BLOCKQUOTE>

	We don't want to give anyone other than the owner the ability to change the program.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the target program <EM>NOT</EM> setuid or setgid?</STRONG>

	<BLOCKQUOTE>

	We do not want to execute programs that will then change our UID/GID again.

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Is the target user/group the same as the program's user/group?</STRONG>

	<BLOCKQUOTE>

	Is the user the owner of the file?

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Can we successfully clean the process environment to ensure safe operations?</STRONG>

	<BLOCKQUOTE>

	suEXEC cleans the process' environment by establishing a safe execution PATH (defined

	during configuration), as well as only passing through those variables whose names

	are listed in the safe environment list (also created during configuration).

	</BLOCKQUOTE>

	</LI>

	<LI><STRONG>Can we successfully become the target program and execute?</STRONG>

	<BLOCKQUOTE>

	Here is where suEXEC ends and the target program begins.

	</BLOCKQUOTE>

	</LI>

	</OL>

</P>



<P ALIGN="LEFT">

This is the standard operation of the the suEXEC wrapper's security model.

It is somewhat stringent and can impose new limitations and guidelines for

CGI/SSI design, but it was developed carefully step-by-step with security

in mind.

</P>



<P ALIGN="LEFT">

For more information as to how this security model can limit your possibilities

in regards to server configuration, as well as what security risks can be avoided

with a proper suEXEC setup, see the <A HREF="#beware">"Beware the Jabberwock"</A>

section of this document.

</P>



<P ALIGN="CENTER">

<STRONG><A HREF="suexec.html">BACK TO CONTENTS</A></STRONG>

</P>



<H3><A NAME="install">Configuring & Installing suEXEC</A></H3>

<P ALIGN="LEFT">

Here's where we begin the fun.  The configuration and installation of suEXEC is

a four step process: edit the suEXEC header file, compile suEXEC, place the

suEXEC binary in its proper location, and configure Apache for use with suEXEC.

</P>



<P ALIGN="LEFT">

<STRONG>EDITING THE SUEXEC HEADER FILE</STRONG><BR>

- From the top-level of the Apache source tree, type:&nbsp;&nbsp;

<STRONG><code>cd support [ENTER]</code></STRONG>

</P>



<P ALIGN="LEFT">

Edit the <code>suexec.h</code> file and change the following macros to

Edit the <code>suexec.h</code> file and change the following macros to

match your local Apache installation.<p>

match your local Apache installation.

</P>



<P ALIGN="LEFT">

<EM>From support/suexec.h</EM>

<EM>From support/suexec.h</EM>

<pre>

<PRE>

     /*

     /*

      * HTTPD_USER -- Define as the username under which Apache normally

      * HTTPD_USER -- Define as the username under which Apache normally

      *               runs.  This is the only user allowed to execute

      *               runs.  This is the only user allowed to execute
@@ -48,12 +285,47 @@ match your local Apache installation.<p> 
      */

      */

     #define HTTPD_USER "www"

     #define HTTPD_USER "www"





     /*

      * UID_MIN -- Define this as the lowest UID allowed to be a target user

      *            for suEXEC.  For most systems, 500 or 100 is common.

      */

     #define UID_MIN 100



     /*

      * GID_MIN -- Define this as the lowest GID allowed to be a target group

      *            for suEXEC.  For most systems, 100 is common.

      */

     #define GID_MIN 100



     /*

      * USERDIR_SUFFIX -- Define to be the subdirectory under users' 

      *                   home 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 

      *                   a location that is not the same as the user's

      *                   home directory as referenced in the passwd file.

      *

      *                   If you have VirtualHosts with a different

      *                   UserDir for each, you will need to define them to

      *                   all reside in one parent directory; then name that

      *                   parent directory here.  IF THIS IS NOT DEFINED

      *                   PROPERLY, ~USERDIR CGI REQUESTS WILL NOT WORK!

      *                   See the suEXEC documentation for more detailed

      *                   information.

      */

     #define USERDIR_SUFFIX "public_html"



     /*

     /*

      * LOG_EXEC -- Define this as a filename if you want all suEXEC

      * LOG_EXEC -- Define this as a filename if you want all suEXEC

      *             transactions and errors logged for auditing and

      *             transactions and errors logged for auditing and

      *             debugging purposes.

      *             debugging purposes.

      */

      */

#define LOG_EXEC "/usr/local/etc/httpd/logs/cgi.log"

     #define LOG_EXEC "/usr/local/etc/httpd/logs/cgi.log" /* Need me? */





     /*

     /*

      * DOC_ROOT -- Define as the DocumentRoot set for Apache.  This

      * DOC_ROOT -- Define as the DocumentRoot set for Apache.  This
@@ -67,95 +339,85 @@ match your local Apache installation.<p> 
      *

      *

      */

      */

     #define SAFE_PATH "/usr/local/bin:/usr/bin:/bin"

     #define SAFE_PATH "/usr/local/bin:/usr/bin:/bin"

</pre>

</PRE>

</P>





<h3>Compiling the suEXEC wrapper</h3>

<P ALIGN="LEFT">

At the shell command prompt, type:&nbsp;&nbsp;<STRONG><code>cc suexec.c

<STRONG>COMPILING THE SUEXEC WRAPPER</STRONG><BR>

-o suexec [ENTER]</code></STRONG>.<p>

You now need to compile the suEXEC wrapper.  At the shell command prompt, 

type:&nbsp;&nbsp;<STRONG><CODE>cc suexec.c -o suexec [ENTER]</CODE></STRONG>.

This should create the <STRONG><em>suexec</em></STRONG> wrapper executable.

This should create the <STRONG><em>suexec</em></STRONG> wrapper executable.

</P>





<h3>Compiling Apache for suEXEC support</h3>

<P ALIGN="LEFT">

<STRONG>COMPILING APACHE FOR USE WITH SUEXEC</STRONG><BR>

By default, Apache is compiled to look for the suEXEC wrapper in the following

By default, Apache is compiled to look for the suEXEC wrapper in the following

location.<p>

location.

</P>



<P ALIGN="LEFT">

<EM>From src/httpd.h</EM>

<EM>From src/httpd.h</EM>

<pre>

<PRE>

     /* The path to the suEXEC wrapper */

     /* The path to the suEXEC wrapper */

#ifndef SUEXEC_BIN

     #define SUEXEC_BIN "/usr/local/etc/httpd/sbin/suexec"

     #define SUEXEC_BIN "/usr/local/etc/httpd/sbin/suexec"

#endif

</PRE>

</pre>

</P>

<p>



<P ALIGN="LEFT">

If your installation requires location of the wrapper program in a different

If your installation requires location of the wrapper program in a different

directory, edit src/httpd.h and recompile your Apache server.

directory, edit src/httpd.h and recompile your Apache server.

See <a href="install.html">Compiling and Installing Apache</a> for more

See <A HREF="install.html">Compiling and Installing Apache</A> for more

info on this process.<p>

info on this process.

</P>





<h3>Installing the suEXEC wrapper</h3>

<P ALIGN="LEFT">

<STRONG>COPYING THE SUEXEC BINARY TO ITS PROPER LOCATION</STRONG><BR>

Copy the <STRONG><em>suexec</em></STRONG> executable created in the

Copy the <STRONG><em>suexec</em></STRONG> executable created in the

exercise above to the defined location for <STRONG>SUEXEC_BIN</STRONG>.<p>

exercise above to the defined location for <STRONG>SUEXEC_BIN</STRONG>.

In order for the wrapper to set the user ID for execution requests it

</P>

must me installed as owner <STRONG><em>root</em></STRONG> and must have



the setuserid execution bit set for file modes.

<P ALIGN="LEFT">

If you are not running a <STRONG><em>root</em></STRONG> user shell, do

<STRONG><CODE>cp suexec /usr/local/etc/httpd/sbin/suexec [ENTER]</CODE></STRONG>

so now and execute the following commands.<p>

</P>





<STRONG><code>chown root /usr/local/etc/httpd/sbin/suexec [ENTER]</code></STRONG><p>

<P ALIGN="LEFT">

<STRONG><code>chmod 4711 /usr/local/etc/httpd/sbin/suexec [ENTER]</code></STRONG><p>

In order for the wrapper to set the user ID, it must me installed as owner 



<STRONG><em>root</em></STRONG> and must have the setuserid execution bit 

<EM>Change the path to the suEXEC wrapper to match your system

set for file modes.  If you are not running a <STRONG><em>root</em></STRONG>

installation.</EM>

user shell, do so now and execute the following commands.



</P>

<hr>





<P ALIGN="LEFT">

<h3><a name="model">Security Model of suEXEC</a></h3>

<STRONG><CODE>chown root /usr/local/etc/httpd/sbin/suexec [ENTER]</CODE></STRONG><BR>

The <STRONG>suEXEC</STRONG> wrapper supplied with Apache performs the

<STRONG><CODE>chmod 4711 /usr/local/etc/httpd/sbin/suexec [ENTER]</CODE></STRONG>

following security checks before it will execute any program passed to

</P>

it for execution.



<ol>

<P ALIGN="CENTER">

<li>User executing the wrapper <STRONG>must be a valid user on this

<STRONG><A HREF="suexec.html">BACK TO CONTENTS</A></STRONG>

 system</STRONG>.

</P>

<li>User executing the wrapper <STRONG>must be the compiled in



 HTTPD_USER</STRONG>.

<H3><A NAME="enable">Enabling & Disabling suEXEC</A></H3>

<li>The command that the request wishes to execute <STRONG>must not

<P ALIGN="LEFT">

 contain a leading / or ../, or the string &quot;/../&quot; anywhere</STRONG>.

<li>The command being executed <STRONG>must reside under the compiled in

 DOC_ROOT</STRONG>.

<li>The current working directory <STRONG>must be a directory</STRONG>.

<li>The current working directory <STRONG>must not be writable by

 <em>group</em> or <em>other</em></STRONG>.

<li>The command being executed <STRONG>cannot be a symbolic link</STRONG>.

<li>The command being executed <STRONG>cannot be writable by

 <em>group</em> or <em>other</em></STRONG>.

<li>The command being executed <STRONG>cannot be a <em>setuid</em> or

 <em>setgid</em> program</STRONG>.

<li>The target UID and GID <STRONG>must be a valid user and group on

 this system</STRONG>.

<li>The target UID and GID to execute as, <STRONG>must match the UID and

 GID of the directory</STRONG>.

<li>The target execution UID and GID <STRONG>must not be the privileged

 ID 0</STRONG>.

</ol>

If any of these issues are too restrictive, or do not seem restrictive

enough, you are welcome to install your own version of the wrapper.

We've given you the rope, now go have fun with it. <STRONG>:-)</STRONG>



<hr>



<h3>Using suEXEC</h3>

After properly installing the <STRONG>suexec</STRONG> wrapper

After properly installing the <STRONG>suexec</STRONG> wrapper

executable, you must kill and restart the Apache server.  A simple

executable, you must kill and restart the Apache server.  A simple

<code><STRONG>kill -1 `cat httpd.pid`</STRONG></code> will not be enough.

<STRONG><CODE>kill -1 `cat httpd.pid`</CODE></STRONG> will not be enough.

Upon startup of the web-server, if Apache finds a properly configured

Upon startup of the web-server, if Apache finds a properly configured

<STRONG>suexec</STRONG> wrapper, it will print the following message to

<STRONG>suexec</STRONG> wrapper, it will print the following message to

the console:<p>

the console:

</P>





<code>Configuring Apache for use with suexec wrapper.</code><p>

<P ALIGN="LEFT">

<CODE>Configuring Apache for use with suexec wrapper.</CODE>

</P>





<P ALIGN="LEFT">

If you don't see this message at server startup, the server is most

If you don't see this message at server startup, the server is most

likely not finding the wrapper program where it expects it, or the

likely not finding the wrapper program where it expects it, or the

executable is not installed <STRONG><em>setuid root</em></STRONG>. Check

executable is not installed <STRONG><EM>setuid root</EM></STRONG>. Check

your installation and try again.<p>

your installation and try again.

</P>





<P ALIGN="LEFT">

One way to use <STRONG>suEXEC</STRONG> is through the

One way to use <STRONG>suEXEC</STRONG> is through the

<a href="mod/core.html#user"><STRONG>User</STRONG></a> and

<a href="mod/core.html#user"><STRONG>User</STRONG></a> and

<a href="mod/core.html#group"><STRONG>Group</STRONG></a> directives in

<a href="mod/core.html#group"><STRONG>Group</STRONG></a> directives in
@@ -176,15 +438,68 @@ The only requirement needed for this feature to work is for CGI 
execution to be enabled for the user and that the script must meet the

execution to be enabled for the user and that the script must meet the

scrutiny of the <a href="#model">security checks</a> above.

scrutiny of the <a href="#model">security checks</a> above.





<hr>

<P ALIGN="CENTER">

<STRONG><A HREF="suexec.html">BACK TO CONTENTS</A></STRONG>

</P>





<h3>Debugging suEXEC</h3>

<H3><A NAME="debug">Debugging suEXEC</A></H3>

<P ALIGN="LEFT">

The suEXEC wrapper will write log information to the location defined in

The suEXEC wrapper will write log information to the location defined in

the <code>suexec.h</code> as indicated above. If you feel you have

the <code>suexec.h</code> as indicated above. If you feel you have

configured and installed the wrapper properly,

configured and installed the wrapper properly, have a look at this log 

have a look at this log and the error_log for the server to see where

and the error_log for the server to see where you may have gone astray.

you may have gone astray.

</P>

<!--#include virtual="footer.html" -->





<P ALIGN="CENTER">

<STRONG><A HREF="suexec.html">BACK TO CONTENTS</A></STRONG>

</P>



<H3><A NAME="jabberwock">Beware the Jabberwock: Warnings & Examples</A></H3>

<P ALIGN="LEFT">

<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://www.apache.org/docs/suexec.html">Online Documentation</A>

version.

</P>



<P ALIGN="LEFT">

There are a few points of interest regarding the wrapper that can cause

limitations on server setup.  Please review these before submitting any

"bugs" regarding suEXEC.

<UL>

	<LH><STRONG>suEXEC Points Of Interest</STRONG></LH>

	<LI>Hierarchy limitations

	<BLOCKQUOTE>

	For security and efficiency reasons, all suexec requests must

	remain within either a top-level document root for 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 document hierarchy to

	take advantage of suEXEC for VirtualHosts. (Example forthcoming.)

	</BLOCKQUOTE>

	</LI>

	<LI>suEXEC's PATH environment variable

	<BLOCKQUOTE>

	This can be a dangerous thing to change.  Make certain every

	path you include in this define is a <STRONG>trusted</STRONG>

	directory.  You don't want to open people up to having someone

	from across the world running a trojan horse on them.

	</BLOCKQUOTE>

	</LI>

	<LI>Altering the suEXEC code

	<BLOCKQUOTE>

	Again, this can cause <STRONG>Big Trouble</STRONG> if you try

	this without knowing what you are doing.  Stay away from it

	if at all possible.

	</BLOCKQUOTE>

	</LI>

</UL>



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