Configure Libreswan to use System Crypto Policy
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Description
Crypto Policies provide a centralized control over crypto algorithms usage of many packages.
Libreswan is supported by system crypto policy, but the Libreswan configuration may be
set up to ignore it.
To check that Crypto Policies settings are configured correctly, ensure that the /etc/ipsec.conf
includes the appropriate configuration file.
In /etc/ipsec.conf, make sure that the following line
is not commented out or superseded by later includes:
include /etc/crypto-policies/back-ends/libreswan.config
Rationale
Overriding the system crypto policy makes the behavior of the Libreswan
service violate expectations, and makes system configuration more
fragmented.
Shell script
The following script can be run on the host to remediate the issue.
#!/bin/bash
function remediate_libreswan_crypto_policy() {
CONFIG_FILE="/etc/ipsec.conf"
if ! grep -qP "^\s*include\s+/etc/crypto-policies/back-ends/libreswan.config\s*(?:#.*)?$" "$CONFIG_FILE" ; then
# the file might not end with a new line
echo -e '\ninclude /etc/crypto-policies/back-ends/libreswan.config' >> "$CONFIG_FILE"
fi
return 0
}
remediate_libreswan_crypto_policy
Ansible playbook
The following playbook can be run with Ansible to remediate the issue.
- name: Configure Libreswan to use System Crypto Policy
lineinfile:
path: /etc/ipsec.conf
line: include /etc/crypto-policies/back-ends/libreswan.config
create: true
tags:
- NIST-800-53-CM-6(a)
- NIST-800-53-MA-4(6)
- NIST-800-53-SC-12(2)
- NIST-800-53-SC-12(3)
- NIST-800-53-SC-13
- PCI-DSS-Req-2.2
- configure_libreswan_crypto_policy
- high_severity
- low_complexity
- low_disruption
- no_reboot_needed
- restrict_strategy
