Apache HTTP Server

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  • Configuring & Installing suEXEC

    This section describes the configuration and installation of the suEXEC feature with the "src/Configure" script.
    (If you use Apache 1.3 you may want to use the Apache AutoConf-style interface (APACI) which is described in the main suEXEC document).


    - From the top-level of the Apache source tree, type:   cd support [ENTER]

    Edit the suexec.h file and change the following macros to match your local Apache installation.

    From support/suexec.h

          * HTTPD_USER -- Define as the username under which Apache normally
          *               runs.  This is the only user allowed to execute
          *               this program.
         #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
          *             transactions and errors logged for auditing and
          *             debugging purposes.
         #define LOG_EXEC "/usr/local/apache/logs/cgi.log" /* Need me? */
          * DOC_ROOT -- Define as the DocumentRoot set for Apache.  This
          *             will be the only hierarchy (aside from UserDirs)
          *             that can be used for suEXEC behavior.
         #define DOC_ROOT "/usr/local/apache/htdocs"
          * SAFE_PATH -- Define a safe PATH environment to pass to CGI executables.
         #define SAFE_PATH "/usr/local/bin:/usr/bin:/bin"

    You now need to compile the suEXEC wrapper. At the shell command prompt, after compiling Apache, type:  make suexec[ENTER]. This should create the suexec wrapper executable.

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

    From src/include/httpd.h

         /* The path to the suExec wrapper, can be overridden in Configuration */
         #ifndef SUEXEC_BIN
         #define SUEXEC_BIN  HTTPD_ROOT "/sbin/suexec"

    If your installation requires location of the wrapper program in a different directory, either add -DSUEXEC_BIN=\"</your/path/to/suexec>\" to your CFLAGS (or edit src/include/httpd.h) and recompile your Apache server. See Compiling and Installing Apache (and the INSTALL file in the source distribution) for more info on this process.

    Copy the suexec executable created in the exercise above to the defined location for SUEXEC_BIN.

    cp suexec /usr/local/apache/sbin/suexec [ENTER]

    In order for the wrapper to set the user ID, it must be installed as owner root and must have the setuserid execution bit set for file modes. If you are not running a root user shell, do so now and execute the following commands.

    chown root /usr/local/apache/sbin/suexec [ENTER]
    chmod 4711 /usr/local/apache/sbin/suexec [ENTER]

    Enabling & Disabling suEXEC

    After properly installing the suexec wrapper executable, you must kill and restart the Apache server. A simple kill -1 `cat httpd.pid` will not be enough. Upon startup of the web-server, if Apache finds a properly configured suexec wrapper, it will print the following message to the console (Apache 1.2):

        Configuring Apache for use with suexec wrapper.
    If you use Apache 1.3 the following message is printed to the error log:
        [notice] suEXEC mechanism enabled (wrapper: /path/to/suexec)

    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 executable is not installed setuid root. Check your installation and try again.


    Apache HTTP Server