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3f08db06526d6901aa08c110b5bc7dde6bc39905nd<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>
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7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen <p>The <strong>suEXEC</strong> feature provides users of the Apache
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen HTTP Server the ability
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen to run <strong>CGI</strong> and <strong>SSI</strong> programs
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen under user IDs different from the user ID of the calling
ce71a46e27f6e2ae210e1f925545aa6e4f74db74jsl web server. Normally, when a CGI or SSI program executes, it
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen runs as the same user who is running the web server.</p>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>Used properly, this feature can reduce
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen considerably the security risks involved with allowing users to
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen develop and run private CGI or SSI programs. However, if suEXEC
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen is improperly configured, it can cause any number of problems
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen and possibly create new holes in your computer's security. If
5f48875017569cc7610b17d852c44e02684d9d5aerikabele you aren't familiar with managing <em>setuid root</em> programs
5f48875017569cc7610b17d852c44e02684d9d5aerikabele and the security issues they present, we highly recommend that
5f48875017569cc7610b17d852c44e02684d9d5aerikabele you not consider using suEXEC.</p>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim<div id="quickview"><ul id="toc"><li><img alt="" src="/images/down.gif" /> <a href="#before">Before we begin</a></li>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim<li><img alt="" src="/images/down.gif" /> <a href="#model">suEXEC Security Model</a></li>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim<li><img alt="" src="/images/down.gif" /> <a href="#install">Configuring & Installing
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim<li><img alt="" src="/images/down.gif" /> <a href="#enable">Enabling & Disabling
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim<li><img alt="" src="/images/down.gif" /> <a href="#usage">Using suEXEC</a></li>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim<li><img alt="" src="/images/down.gif" /> <a href="#debug">Debugging suEXEC</a></li>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim<li><img alt="" src="/images/down.gif" /> <a href="#jabberwock">Beware the Jabberwock:
30471a4650391f57975f60bbb6e4a90be7b284bfhumbedooh</ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>Before jumping head-first into this document,
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen you should be aware that certain assumptions are made about you and
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen the environment in which you will be using suexec.</p>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>First, it is assumed that you are using a UNIX
e884f58207082fa2136d5fc86635c31252338948erikabele derivative operating system that is capable of
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>setuid</strong> and <strong>setgid</strong> operations.
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen All command examples are given in this regard. Other platforms,
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen if they are capable of supporting suEXEC, may differ in their
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen configuration.</p>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>Second, it is assumed you are familiar with
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen some basic concepts of your computer's security and its
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen administration. This involves an understanding of
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>setuid/setgid</strong> operations and the various
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen effects they may have on your system and its level of
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen security.</p>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>Third, it is assumed that you are using an
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>unmodified</strong> version of suEXEC code. All code
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen for suEXEC has been carefully scrutinized and tested by the
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen developers as well as numerous beta testers. Every precaution
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen has been taken to ensure a simple yet solidly safe base of
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen code. Altering this code can cause unexpected problems and new
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen security risks. It is <strong>highly</strong> recommended you
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen not alter the suEXEC code unless you are well versed in the
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen particulars of security programming and are willing to share
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen your work with the Apache HTTP Server development team for consideration.</p>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>Fourth, and last, it has been the decision of
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen the Apache HTTP Server development team to <strong>NOT</strong> make suEXEC part of
9045c2ce2212b7e911e8a27a4ae6aa9ca73f3d91rbowen the default installation of Apache httpd. To this end, suEXEC
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen configuration requires of the administrator careful attention
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen to details. After due consideration has been given to the
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen various settings for suEXEC, the administrator may install
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen suEXEC through normal installation methods. The values for
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen these settings need to be carefully determined and specified by
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen the administrator to properly maintain system security during
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen the use of suEXEC functionality. It is through this detailed
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen process that we hope to limit suEXEC
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen installation only to those who are careful and determined
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen enough to use it.</p>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<h2><a name="model" id="model">suEXEC Security Model</a></h2>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>Before we begin configuring and installing
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen suEXEC, we will first discuss the security model you are about
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen to implement. By doing so, you may better understand what
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen exactly is going on inside suEXEC and what precautions are
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen taken to ensure your system's security.</p>
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen "wrapper" program that is called by the main Apache HTTP Server.
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen This wrapper is called when an HTTP request is made for a CGI
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen or SSI program that the administrator has designated to run as
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen a userid other than that of the main server. When such a
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen request is made, Apache httpd provides the suEXEC wrapper with the
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen program's name and the user and group IDs under which the
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen program is to execute.</p>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>The wrapper then employs the following process
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen to determine success or failure -- if any one of these
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen conditions fail, the program logs the failure and exits with an
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen error, otherwise it will continue:</p>
5f48875017569cc7610b17d852c44e02684d9d5aerikabele <strong>Is the user executing this wrapper a valid user of
e1e8390280254f7f0580d701e583f670643d4f3fnilgun this system?</strong>
5f48875017569cc7610b17d852c44e02684d9d5aerikabele This is to ensure that the user executing the wrapper is
5f48875017569cc7610b17d852c44e02684d9d5aerikabele truly a user of the system.
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>Was the wrapper called with the proper number of
e1e8390280254f7f0580d701e583f670643d4f3fnilgun arguments?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen The wrapper will only execute if it is given the proper
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen number of arguments. The proper argument format is known
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen to the Apache HTTP Server. If the wrapper is not receiving
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen the proper number of arguments, it is either being
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen hacked, or there is something wrong with the suEXEC
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen portion of your Apache httpd binary.
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>Is this valid user allowed to run the
e1e8390280254f7f0580d701e583f670643d4f3fnilgun wrapper?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen Is this user the user allowed to run this wrapper? Only
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen one user (the Apache user) is allowed to execute this
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele <strong>Does the target CGI or SSI program have an unsafe
e1e8390280254f7f0580d701e583f670643d4f3fnilgun hierarchical reference?</strong>
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele Does the target CGI or SSI program's path contain a leading
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele '/' or have a '..' backreference? These are not allowed; the
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele target CGI/SSI program must reside within suEXEC's document
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele root (see <code>--with-suexec-docroot=<em>DIR</em></code>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen Does the target user exist?
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen Does the target group exist?
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>Is the target user <em>NOT</em> superuser?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>Is the target userid <em>ABOVE</em> the minimum ID
e1e8390280254f7f0580d701e583f670643d4f3fnilgun number?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen The minimum user ID number is specified during
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen configuration. This allows you to set the lowest possible
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen userid that will be allowed to execute CGI/SSI programs.
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen This is useful to block out "system" accounts.
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>Is the target group <em>NOT</em> the superuser
e1e8390280254f7f0580d701e583f670643d4f3fnilgun group?</strong>
5f48875017569cc7610b17d852c44e02684d9d5aerikabele Presently, suEXEC does not allow the <code><em>root</em></code>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>Is the target groupid <em>ABOVE</em> the minimum ID
e1e8390280254f7f0580d701e583f670643d4f3fnilgun number?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen The minimum group ID number is specified during
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen configuration. This allows you to set the lowest possible
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen groupid that will be allowed to execute CGI/SSI programs.
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen This is useful to block out "system" groups.
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>Can the wrapper successfully become the target user
e1e8390280254f7f0580d701e583f670643d4f3fnilgun and group?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen Here is where the program becomes the target user and
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen group via setuid and setgid calls. The group access list
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen is also initialized with all of the groups of which the
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen user is a member.
5f48875017569cc7610b17d852c44e02684d9d5aerikabele <strong>Can we change directory to the one in which the target
5f48875017569cc7610b17d852c44e02684d9d5aerikabele If it doesn't exist, it can't very well contain files. If we
157312a2bcbad225c12462fc6d74b1aa3f32dceehumbedooh can't change directory to it, it might as well not exist.
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen <strong>Is the directory within the httpd webspace?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen If the request is for a regular portion of the server, is
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele the requested directory within suEXEC's document root? If
e1e8390280254f7f0580d701e583f670643d4f3fnilgun the request is for a <code class="directive"><a href="/mod/mod_userdir.html#userdir">UserDir</a></code>, is the requested directory
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele within the directory configured as suEXEC's userdir (see
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele <a href="#install">suEXEC's configuration options</a>)?
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>Is the directory <em>NOT</em> writable by anyone
e1e8390280254f7f0580d701e583f670643d4f3fnilgun else?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen We don't want to open up the directory to others; only
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen the owner user may be able to alter this directories
e1e8390280254f7f0580d701e583f670643d4f3fnilgun <strong>Does the target CGI/SSI program exist?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen If it doesn't exists, it can't very well be executed.
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele <strong>Is the target CGI/SSI program <em>NOT</em> writable
e1e8390280254f7f0580d701e583f670643d4f3fnilgun by anyone else?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen We don't want to give anyone other than the owner the
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele <strong>Is the target CGI/SSI program <em>NOT</em> setuid or
e1e8390280254f7f0580d701e583f670643d4f3fnilgun setgid?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen We do not want to execute programs that will then change
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>Is the target user/group the same as the program's
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen Is the user the owner of the file?
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>Can we successfully clean the process environment
e1e8390280254f7f0580d701e583f670643d4f3fnilgun to ensure safe operations?</strong>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen suEXEC cleans the process' environment by establishing a
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen safe execution PATH (defined during configuration), as
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen well as only passing through those variables whose names
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen are listed in the safe environment list (also created
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen during configuration).
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele <strong>Can we successfully become the target CGI/SSI program
e1e8390280254f7f0580d701e583f670643d4f3fnilgun and execute?</strong>
41dd95074cc6924ee56c53ba11aa6faf59b2ee13erikabele Here is where suEXEC ends and the target CGI/SSI program begins.
e884f58207082fa2136d5fc86635c31252338948erikabele <p>This is the standard operation of the
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen suEXEC wrapper's security model. It is somewhat stringent and
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen can impose new limitations and guidelines for CGI/SSI design,
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen but it was developed carefully step-by-step with security in
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>For more information as to how this security
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen model can limit your possibilities in regards to server
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen configuration, as well as what security risks can be avoided
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive with a proper suEXEC setup, see the <a href="#jabberwock">"Beware the Jabberwock"</a> section of this
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen document.</p>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<h2><a name="install" id="install">Configuring & Installing
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <dd>This option enables the suEXEC feature which is never
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen installed or activated by default. At least one
5f48875017569cc7610b17d852c44e02684d9d5aerikabele <code>--with-suexec-xxxxx</code> option has to be provided
5f48875017569cc7610b17d852c44e02684d9d5aerikabele together with the <code>--enable-suexec</code> option to let
5f48875017569cc7610b17d852c44e02684d9d5aerikabele APACI accept your request for using the suEXEC feature.</dd>
5f48875017569cc7610b17d852c44e02684d9d5aerikabele <dd>The path to the <code>suexec</code> binary must be hard-coded
5f48875017569cc7610b17d852c44e02684d9d5aerikabele in the server for security reasons. Use this option to override
5bb304d44f4a7046289c9c7dbeef63843bff9613rbowen <dt><code>--with-suexec-caller=<em>UID</em></code></dt>
d0dd037bdab65b455b4056d58be501ca14e61dfemartin <dd>The <a href="mod/mpm_common.html#user">username</a> under which
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen httpd normally runs. This is the only user allowed to
f6066dc0a6ad0432b74774e290c04c3cc4aa2dafrbowen execute the suEXEC wrapper.</dd>
5bb304d44f4a7046289c9c7dbeef63843bff9613rbowen <dt><code>--with-suexec-userdir=<em>DIR</em></code></dt>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <dd>Define to be the subdirectory under users' home
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen directories where suEXEC access should be allowed. All
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen executables under this directory will be executable by suEXEC
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen as the user so they should be "safe" programs. If you are
e1e8390280254f7f0580d701e583f670643d4f3fnilgun using a "simple" <code class="directive"><a href="/mod/mod_userdir.html#userdir">UserDir</a></code>
e1e8390280254f7f0580d701e583f670643d4f3fnilgun directive (ie. one without a "*" in it) this should be set to the same
e1e8390280254f7f0580d701e583f670643d4f3fnilgun 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
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen a location that is not the same as the user's home directory
e1e8390280254f7f0580d701e583f670643d4f3fnilgun as referenced in the <code>passwd</code> file. Default value is
e1e8390280254f7f0580d701e583f670643d4f3fnilgun If you have virtual hosts with a different <code class="directive"><a href="/mod/mod_userdir.html#userdir">UserDir</a></code> for each,
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen you will need to define them to all reside in one parent
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen directory; then name that parent directory here. <strong>If
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen this is not defined properly, "~userdir" cgi requests will
ee8d84bbd543e3e808e81e4e802d960548ce30d1aaron <dt><code>--with-suexec-docroot=<em>DIR</em></code></dt>
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen <dd>Define as the DocumentRoot set for httpd. This will be
e1e8390280254f7f0580d701e583f670643d4f3fnilgun 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
e1e8390280254f7f0580d701e583f670643d4f3fnilgun default directory is the <code>--datadir</code> value with the suffix
e1e8390280254f7f0580d701e583f670643d4f3fnilgun "<code>/htdocs</code>", <em>e.g.</em> if you configure with
e1e8390280254f7f0580d701e583f670643d4f3fnilgun "<code>/home/apache/htdocs</code>" is used as document root for the
e1e8390280254f7f0580d701e583f670643d4f3fnilgun suEXEC wrapper.</dd>
5bb304d44f4a7046289c9c7dbeef63843bff9613rbowen <dt><code>--with-suexec-uidmin=<em>UID</em></code></dt>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <dd>Define this as the lowest UID allowed to be a target user
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen for suEXEC. For most systems, 500 or 100 is common. Default
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen value is 100.</dd>
5bb304d44f4a7046289c9c7dbeef63843bff9613rbowen <dt><code>--with-suexec-gidmin=<em>GID</em></code></dt>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <dd>Define this as the lowest GID allowed to be a target
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen group for suEXEC. For most systems, 100 is common and
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen therefore used as default value.</dd>
ee8d84bbd543e3e808e81e4e802d960548ce30d1aaron <dt><code>--with-suexec-logfile=<em>FILE</em></code></dt>
ee8d84bbd543e3e808e81e4e802d960548ce30d1aaron <dd>This defines the filename to which all suEXEC
ee8d84bbd543e3e808e81e4e802d960548ce30d1aaron transactions and errors are logged (useful for auditing and
ee8d84bbd543e3e808e81e4e802d960548ce30d1aaron debugging purposes). By default the logfile is named
e1e8390280254f7f0580d701e583f670643d4f3fnilgun "<code>suexec_log</code>" and located in your standard logfile
a6f3268ea98277eee9258bc6aed3e93f3df54633jorton <dd>If defined, suexec will log notices and errors to syslog
a6f3268ea98277eee9258bc6aed3e93f3df54633jorton instead of a logfile. This option must be combined
5bb304d44f4a7046289c9c7dbeef63843bff9613rbowen <dt><code>--with-suexec-safepath=<em>PATH</em></code></dt>
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <dd>Define a safe PATH environment to pass to CGI
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen executables. Default value is
e1e8390280254f7f0580d701e583f670643d4f3fnilgun <p>If you have enabled the suEXEC feature with the
e1e8390280254f7f0580d701e583f670643d4f3fnilgun <code>--enable-suexec</code> option the <code>suexec</code> binary
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen (together with httpd itself) is automatically built if you execute
e1e8390280254f7f0580d701e583f670643d4f3fnilgun <p>After all components have been built you can execute the
e1e8390280254f7f0580d701e583f670643d4f3fnilgun command <code>make install</code> to install them. The binary image
e1e8390280254f7f0580d701e583f670643d4f3fnilgun <code>suexec</code> is installed in the directory defined by the
e1e8390280254f7f0580d701e583f670643d4f3fnilgun <code>--sbindir</code> option. The default location is
e1e8390280254f7f0580d701e583f670643d4f3fnilgun privileges</em></strong> for the installation step. In order
e1e8390280254f7f0580d701e583f670643d4f3fnilgun for the wrapper to set the user ID, it must be installed as
e1e8390280254f7f0580d701e583f670643d4f3fnilgun owner <code><em>root</em></code> and must have the setuserid
e1e8390280254f7f0580d701e583f670643d4f3fnilgun execution bit set for file modes.</p>
e1e8390280254f7f0580d701e583f670643d4f3fnilgun <p>Although the suEXEC wrapper will check to ensure that its
e1e8390280254f7f0580d701e583f670643d4f3fnilgun caller is the correct user as specified with the
e1e8390280254f7f0580d701e583f670643d4f3fnilgun <code>--with-suexec-caller</code> <code class="program"><a href="/programs/configure.html">configure</a></code>
e1e8390280254f7f0580d701e583f670643d4f3fnilgun option, there is
e1e8390280254f7f0580d701e583f670643d4f3fnilgun always the possibility that a system or library call suEXEC uses
e1e8390280254f7f0580d701e583f670643d4f3fnilgun before this check may be exploitable on your system. To counter
e1e8390280254f7f0580d701e583f670643d4f3fnilgun this, and because it is best-practise in general, you should use
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen filesystem permissions to ensure that only the group httpd
e1e8390280254f7f0580d701e583f670643d4f3fnilgun runs as may execute suEXEC.</p>
e1e8390280254f7f0580d701e583f670643d4f3fnilgun <p>If for example, your web server is configured to run as:</p>
c3c006c28c5b03892ccaef6e4d2cbb15a13a2072rbowenGroup webgroup
e1e8390280254f7f0580d701e583f670643d4f3fnilgun <p>and <code class="program"><a href="/programs/suexec.html">suexec</a></code> is installed at
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen <p>This will ensure that only the group httpd runs as can even
e1e8390280254f7f0580d701e583f670643d4f3fnilgun execute the suEXEC wrapper.</p>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen <p>Upon startup of httpd, it looks for the file
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim <code class="program"><a href="/programs/suexec.html">suexec</a></code> in the directory defined by the
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen "/usr/local/apache/sbin/suexec"). If httpd finds a properly
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen configured suEXEC wrapper, it will print the following message
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen to the error log:</p>
9bcfc3697a91b5215893a7d0206865b13fc72148nd [notice] suEXEC mechanism enabled (wrapper: <var>/path/to/suexec</var>)
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>If you don't see this message at server startup, the server is
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen most likely not finding the wrapper program where it expects
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive it, or the executable is not installed <em>setuid root</em>.</p>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>If you want to enable the suEXEC mechanism for the first time
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen and an Apache HTTP Server is already running you must kill and
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen restart httpd. Restarting it with a simple HUP or USR1 signal
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive will not be enough. </p>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>If you want to disable suEXEC you should kill and restart
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen httpd after you have removed the <code class="program"><a href="/programs/suexec.html">suexec</a></code> file.</p>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
53feb1d7d644e42dcc617b35516598bb15e8bcc1slive <p>Requests for CGI programs will call the suEXEC wrapper only if
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim they are for a virtual host containing a <code class="directive"><a href="/mod/mod_suexec.html#suexecusergroup">SuexecUserGroup</a></code> directive or if
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim they are processed by <code class="module"><a href="/mod/mod_userdir.html">mod_userdir</a></code>.</p>
181e56d8b348d301d615ccf5465ae600fee2867berikabele <p><strong>Virtual Hosts:</strong><br /> One way to use the suEXEC
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim wrapper is through the <code class="directive"><a href="/mod/mod_suexec.html#suexecusergroup">SuexecUserGroup</a></code> directive in
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim <code class="directive"><a href="/mod/core.html#virtualhost">VirtualHost</a></code> definitions. By
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive setting this directive to values different from the main server
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive user ID, all requests for CGI resources will be executed as the
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim <em>User</em> and <em>Group</em> defined for that <code class="directive"><a href="/mod/core.html#virtualhost"><VirtualHost></a></code>. If this
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim directive is not specified for a <code class="directive"><a href="/mod/core.html#virtualhost"><VirtualHost></a></code> then the main server userid
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive is assumed.</p>
53feb1d7d644e42dcc617b35516598bb15e8bcc1slive <p><strong>User directories:</strong><br /> Requests that are
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim processed by <code class="module"><a href="/mod/mod_userdir.html">mod_userdir</a></code> will call the suEXEC
53feb1d7d644e42dcc617b35516598bb15e8bcc1slive wrapper to execute CGI programs under the userid of the requested
53feb1d7d644e42dcc617b35516598bb15e8bcc1slive user directory. The only requirement needed for this feature to
53feb1d7d644e42dcc617b35516598bb15e8bcc1slive work is for CGI execution to be enabled for the user and that the
53feb1d7d644e42dcc617b35516598bb15e8bcc1slive script must meet the scrutiny of the <a href="#model">security
53feb1d7d644e42dcc617b35516598bb15e8bcc1slive checks</a> above. See also the
53feb1d7d644e42dcc617b35516598bb15e8bcc1slive <code>--with-suexec-userdir</code> <a href="#install">compile
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim time option</a>.</p> </div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>The suEXEC wrapper will write log information
5f48875017569cc7610b17d852c44e02684d9d5aerikabele to the file defined with the <code>--with-suexec-logfile</code>
a6f3268ea98277eee9258bc6aed3e93f3df54633jorton option as indicated above, or to syslog if <code>--with-suexec-syslog</code>
a6f3268ea98277eee9258bc6aed3e93f3df54633jorton is used. If you feel you have configured and
a6f3268ea98277eee9258bc6aed3e93f3df54633jorton installed the wrapper properly, have a look at the log and the
a6f3268ea98277eee9258bc6aed3e93f3df54633jorton error_log for the server to see where you may have gone astray.
a6f3268ea98277eee9258bc6aed3e93f3df54633jorton The output of <code>"suexec -V"</code> will show the options
a6f3268ea98277eee9258bc6aed3e93f3df54633jorton used to compile suexec, if using a binary distribution.</p>
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
5a58787efeb02a1c3f06569d019ad81fd2efa06end<h2><a name="jabberwock" id="jabberwock">Beware the Jabberwock:
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen complete. For the latest revision of this section of the
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen documentation, see the <a href="http://httpd.apache.org/docs/trunk/suexec.html">Online
ca0e3098838c1f9aa77bcdfc3df99cf9aa0f9383slive <p>There are a few points of interest regarding
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen the wrapper that can cause limitations on server setup. Please
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen review these before submitting any "bugs" regarding suEXEC.</p>
e1e8390280254f7f0580d701e583f670643d4f3fnilgun Hierarchy limitations
5f48875017569cc7610b17d852c44e02684d9d5aerikabele For security and efficiency reasons, all suEXEC requests
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen must remain within either a top-level document root for
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen virtual host requests, or one top-level personal document
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen root for userdir requests. For example, if you have four
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen VirtualHosts configured, you would need to structure all
7d37d896e4bce35ac213fededef06aff2d2f25d7rbowen of your VHosts' document roots off of one main httpd
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen document hierarchy to take advantage of suEXEC for
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen VirtualHosts. (Example forthcoming.)
e1e8390280254f7f0580d701e583f670643d4f3fnilgun suEXEC's PATH environment variable
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen This can be a dangerous thing to change. Make certain
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen every path you include in this define is a
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen <strong>trusted</strong> directory. You don't want to
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen open people up to having someone from across the world
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen running a trojan horse on them.
e1e8390280254f7f0580d701e583f670643d4f3fnilgun Altering the suEXEC code
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen Again, this can cause <strong>Big Trouble</strong> if you
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen try this without knowing what you are doing. Stay away
57d0156f7bbd9ea3a72342cf9912aba61d118702rbowen from it if at all possible.
7add1372edb1ee95a2c4d1314df4c7567bda7c62jim<p><span>Available Languages: </span><a href="/en/suexec.html" title="English"> en </a> |
af84459fbf938e508fd10b01cb8d699c79083813takashi<a href="/fr/suexec.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> |
7f5b59ccc63c0c0e3e678a168f09ee6a2f51f9d0nd<a href="/ja/suexec.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
e1e8390280254f7f0580d701e583f670643d4f3fnilgun<a href="/ko/suexec.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> |
f086b4b402fa9a2fefc7dda85de2a3cc1cd0a654rjung<a href="/tr/suexec.html" hreflang="tr" rel="alternate" title="T�rk�e"> tr </a></p>
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