Apache Module: MPM ITK

Last modified: November 1, 2022

Overview

The mod_mpm_itk Apache module causes the Apache process to switch to the domain owner’s user identifier (UID) and group identifier (GID) before it responds to the request. This allows each user to isolate their files from others with the standard file permission settings.

Note:

To query all of the SETUID and SETGID values on a server, run the following command:

find / -type f \( -perm -04000 -o -perm -02000 \) \-exec ls -lg {} \;

Usage

Only use this module if you run modules that do not require thread-aware code.

Requirements

This module requires EasyApache 4, Apache 2.4, MPM Prefork, and the CGI PHP handler.

Warning:

We strongly recommend that you only install the mod_mpm_itk Apache module on systems with Secure Computing Mode (seccomp v2) enabled in the kernel.

Compatibility

The MPM ITK module is not compatible with the following functions:

mod_http2
mod_ruid2
mod_userdir
EAccelerator
Mod suPHP
CloudLinux’s™ PHP Selector feature
cPanel’s Leech Protection interface (cPanel » Home » Security » Leech Protection)

Note:

If you select the MPM ITK option, we strongly recommend that you remove the Leech Protection feature from your users’ feature lists. Use WHM’s Feature Manager interface (WHM » Home » Packages » Feature Manager) to change your users’ feature lists.

setuid() and setgid() restrictions

The MPM ITK Apache module implements restrictions on the use of the setuid() function and the setgid() function. As a result, scripts that depend on these functions may encounter problems. This includes scripts that use the mail() function, the shell_exec function, or the sudo command.

You can resolve these restrictions with one of the following methods:

Don’t use the MPM ITK Apache module.
Update your script to no longer require escalated privileges.
Turn off security and allow users to execute scripts as the root user. You can allow users with UID or GID between 0 and 4294496296 to bypass security if you add the following code to your /etc/apache2/conf.d/includes/pre_virtualhost_global.conf file:
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<IfModule mpm_itk.c> LimitUIDRange 0 4294496296 LimitGIDRange 0 4294496296 </IfModule>

Warning:

We strongly recommend that you do not enable root privileges for your users. This action has major security implications and could endanger your server.

How to install or uninstall the module

Note:

The cPanel Default + MPM ITK EasyApache 4 profile contains the mod_mpm_itk Apache module by default.

In the interface

The easiest way to install or uninstall the mod_mpm_itk Apache module is with WHM’s EasyApache 4 interface (WHM » Home » Software » EasyApache 4).

On the command line

Install the module

You must manually uninstall MPM Worker and install MPM Prefork in order for the MPM ITK module to work correctly. You must perform the following steps on the command line before you install the MPM ITK module:

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yum shell
remove ea-apache24-mod_mpm_worker
remove ea-apache24-mod_cgid
install ea-apache24-mod_mpm_prefork
install ea-apache24-mod_cgi
run
quit

To install the mod_mpm_itk Apache module, run the following command on the command line:

yum install ea-apache24-mod_mpm_itk

Uninstall the module

To uninstall the mod_mpm_itk Apache module, run the following command on the command line:

yum remove ea-apache24-mod_mpm_itk

After you uninstall the MPM ITK module, if you wish you use the MPM Worker, you must perform the following steps on the command line:

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yum shell
remove ea-apache24-mod_mpm_prefork
remove ea-apache24-mod_cgi
install ea-apache24-mod_mpm_worker
install ea-apache24-mod_cgid
run
quit