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5.16. Configuring Firewall Lockdown
Local applications or services are able to change the firewall configuration if they are running as
root (for example, libvirt). With this feature, the administrator can lock the firewall configuration so that either no applications or only applications that are added to the lockdown whitelist are able to request firewall changes. The lockdown settings default to disabled. If enabled, the user can be sure that there are no unwanted configuration changes made to the firewall by local applications or services.
5.16.1. Configuring Lockdown with the Command-Line Client
To query whether lockdown is enabled, use the following command as
root:
~]# firewall-cmd --query-lockdown
The command prints yes with exit status 0 if lockdown is enabled. It prints no with exit status 1 otherwise.
To enable lockdown, enter the following command as
root:
~]# firewall-cmd --lockdown-on
To disable lockdown, use the following command as
root:
~]# firewall-cmd --lockdown-off
5.16.2. Configuring Lockdown Whitelist Options with the Command-Line Client
The lockdown whitelist can contain commands, security contexts, users and user IDs. If a command entry on the whitelist ends with an asterisk “*”, then all command lines starting with that command will match. If the “*” is not there then the absolute command including arguments must match.
The context is the security (SELinux) context of a running application or service. To get the context of a running application use the following command:
~]$ ps -e --context
That command returns all running applications. Pipe the output through the grep tool to get the application of interest. For example:
~]$ ps -e --context | grep example_program
To list all command lines that are on the whitelist, enter the following command as
root:
~]# firewall-cmd --list-lockdown-whitelist-commands
To add a command command to the whitelist, enter the following command as
root:
~]# firewall-cmd --add-lockdown-whitelist-command='/usr/bin/python -Es /usr/bin/command'
To remove a command command from the whitelist, enter the following command as
root:
~]# firewall-cmd --remove-lockdown-whitelist-command='/usr/bin/python -Es /usr/bin/command'
To query whether the command command is on the whitelist, enter the following command as
root:
~]# firewall-cmd --query-lockdown-whitelist-command='/usr/bin/python -Es /usr/bin/command'
The command prints yes with exit status 0 if true. It prints no with exit status 1 otherwise.
To list all security contexts that are on the whitelist, enter the following command as
root:
~]# firewall-cmd --list-lockdown-whitelist-contexts
To add a context context to the whitelist, enter the following command as
root:
~]# firewall-cmd --add-lockdown-whitelist-context=context
To remove a context context from the whitelist, enter the following command as
root:
~]# firewall-cmd --remove-lockdown-whitelist-context=context
To query whether the context context is on the whitelist, enter the following command as
root:
~]# firewall-cmd --query-lockdown-whitelist-context=context
Prints yes with exit status 0, if true, prints no with exit status 1 otherwise.
To list all user IDs that are on the whitelist, enter the following command as
root:
~]# firewall-cmd --list-lockdown-whitelist-uids
To add a user ID uid to the whitelist, enter the following command as
root:
~]# firewall-cmd --add-lockdown-whitelist-uid=uid
To remove a user ID uid from the whitelist, enter the following command as
root:
~]# firewall-cmd --remove-lockdown-whitelist-uid=uid
To query whether the user ID uid is on the whitelist, enter the following command:
~]$ firewall-cmd --query-lockdown-whitelist-uid=uid
Prints yes with exit status 0, if true, prints no with exit status 1 otherwise.
To list all user names that are on the whitelist, enter the following command as
root:
~]# firewall-cmd --list-lockdown-whitelist-users
To add a user name user to the whitelist, enter the following command as
root:
~]# firewall-cmd --add-lockdown-whitelist-user=user
To remove a user name user from the whitelist, enter the following command as
root:
~]# firewall-cmd --remove-lockdown-whitelist-user=user
To query whether the user name user is on the whitelist, enter the following command:
~]$ firewall-cmd --query-lockdown-whitelist-user=user
Prints yes with exit status 0, if true, prints no with exit status 1 otherwise.
5.16.3. Configuring Lockdown Whitelist Options with Configuration Files
The default whitelist configuration file contains the NetworkManager context and the default context of libvirt. The user ID 0 is also on the list.
<?xml version="1.0" encoding="utf-8"?> <whitelist> <selinux context="system_u:system_r:NetworkManager_t:s0"/> <selinux context="system_u:system_r:virtd_t:s0-s0:c0.c1023"/> <user id="0"/> </whitelist>
Following is an example whitelist configuration file enabling all commands for the
firewall-cmd utility, for a user called user whose user ID is 815:
<?xml version="1.0" encoding="utf-8"?> <whitelist> <command name="/usr/bin/python -Es /bin/firewall-cmd*"/> <selinux context="system_u:system_r:NetworkManager_t:s0"/> <user id="815"/> <user name="user"/> </whitelist>This example shows both
user id and user name, but only one option is required. Python is the interpreter and is prepended to the command line. You can also use a specific command, for example: /usr/bin/python /bin/firewall-cmd --lockdown-on--lockdown-on command is allowed.
Note
In Red Hat Enterprise Linux 7, all utilities are placed in the
/usr/bin/ directory and the /bin/ directory is sym-linked to the /usr/bin/ directory. In other words, although the path for firewall-cmd when run as root might resolve to /bin/firewall-cmd, /usr/bin/firewall-cmd can now be used. All new scripts should use the new location. But be aware that if scripts that run as root have been written to use the /bin/firewall-cmd path, then that command path must be whitelisted in addition to the /usr/bin/firewall-cmd path traditionally used only for non-root users.
The “*” at the end of the name attribute of a command means that all commands that start with this string will match. If the “*” is not there then the absolute command including arguments must match.
