home-server/roles/openvpn/tasks/main.yml

---
# The home-server project produces a multi-purpose setup using Ansible.
# Copyright © 2018–2023 Y. Gablin, under the GPL-3.0-or-later license.
# Full licensing information in the LICENSE file, or gnu.org/licences/gpl-3.0.txt if the file is missing.

### UPSTREAM BEGIN ⇒ ###
- name: pull prerequisites from upstream
  include_role: name=etckeeper.inc allow_duplicates=true tasks_from=upstream.yml
  vars:
    msg: OpenVPN
### ⇐ UPSTREAM BEGIN ###

- name: install software
  package:
    name: {{item}}
  with_items:
    - iproute2
    - openvpn
    # jq is needed by no-VPN network-namespace script
    - jq

### UPSTREAM END ⇒ ###
- name: merge upstream
  include_role: name=etckeeper.inc allow_duplicates=true tasks_from=merge.yml
  vars:
    msg: OpenVPN
### ⇐ UPSTREAM END ###

- name: VPN configuration
  template:
    src: templates/vpn.conf.j2
    dest: /etc/openvpn/client/{{vpn_name}}.conf
    owner: openvpn
    group: network
    mode: 0600
  notify:
    - restart openvpn-client.service

- name: VPN TLS auth key
  copy:
    content: |
      {{vpn_tls_auth_key}}      
    dest: /etc/openvpn/client/{{vpn_name}}-ta.key
    owner: openvpn
    group: network
    mode: 0600
  notify:
    - restart openvpn-client.service

- name: VPN credentials
  copy:
    content: |
      {{vpn_login}}
      {{vpn_password}}      
    dest: /etc/openvpn/client/{{vpn_name}}.userpass
    owner: openvpn
    group: network
    mode: 0400
  notify:
    - restart openvpn-client.service

- name: prepare to override OpenVPN security
  file:
    path: /etc/systemd/system/openvpn-client@{{vpn_name}}.service.d
    state: directory
    mode: 0755
  notify:
    - restart openvpn-client.service

- name: override OpenVPN security with systemd
  copy:
    content: |
      [Service]
      ExecStart=
      ExecStart=/usr/bin/openvpn --suppress-timestamps --nobind --config %i.conf --auth-user-pass /etc/openvpn/client/%i.userpass      
    dest: /etc/systemd/system/openvpn-client@{{vpn_name}}.service.d/auth-user-pass.conf
    mode: 0644
  notify:
    - restart openvpn-client.service

- name: store DMZ IP (front)
  set_fact:
    current_IP: "{{DMZ_IP}}"
  when:
    - (inventory_hostname in groups['front'])

- name: store SafeZone IP (back)
  set_fact:
    current_IP: "{{SafeZone_IP}}"
  when:
    - (inventory_hostname in groups['back'])

- name: creation script for no-VPN network namespace
  copy:
    content: |
      #!/bin/bash
      # https://www.baeldung.com/linux/different-network-interfaces-processes
      set -e

      # find network settings associated with known IP address
      host_if=$(ip -j -4 address | jq -r '.[] | select(any(.addr_info[]; .local == "{{current_IP}}")) | .ifname')
      gateway=$(ip -j -4 route | jq -r '.[] | select(.dst == "default") | .gateway')

      # create namespace if it does not exist
      if ! ip netns list | grep -Fxq no-vpn; then
        ip netns add no-vpn
      fi

      # configure namespace if not done
      # $1: interface name; $2: CIDR
      function setup() {
        if ! ip -n no-vpn link show up dev $1 | grep -q .; then
          ip -n no-vpn link set $1 up
        fi
        if [ -z "$(ip -n no-vpn -4 address show dev $1)" ]; then
          ip -n no-vpn address add $2 dev $1
        fi
      }
      if ! ip -n no-vpn link show dev if_isp &>/dev/null; then
        ip link add link $host_if if_isp netns no-vpn type ipvlan mode l2
      fi
      setup if_isp {{vpn_avoiding_ip_cidr}}
      setup lo 127.0.0.1/8

      # set gateway if not set
      if ! ip -n no-vpn -4 route | grep -q ^default; then
        ip -n no-vpn route add default via $gateway dev if_isp
      fi      
    dest: /usr/local/bin/create-no-vpn-namespace.sh
    mode: 0700
  notify:
    - restart no-vpn network namespace

- name: removal script for no-VPN network namespace
  copy:
    content: |
      #!/bin/sh
      ip netns delete no-vpn      
    dest: /usr/local/bin/delete-no-vpn-namespace.sh
    mode: 0700
  notify:
    - restart no-vpn network namespace

- name: no-VPN network namespace firewall
  template:
    src: templates/nftables.conf.j2
    dest: /etc/netns/no-vpn/nftables.conf
    mode: 0600
  notify:
    - restart no-vpn network namespace

# https://github.com/mqus/nft-rules/blob/master/files/SSDP_client.md
- name: systemctl service for no-VPN network namespace
  copy:
    content: |
      [Unit]
      Description=No-VPN network namespace
      After=network-online.target openvpn.service
      Wants=network-online.target openvpn.service
      [Service]
      Type=oneshot
      RemainAfterExit=true
      ExecStart=/usr/local/bin/create-no-vpn-namespace.sh
      ExecStartPost=/usr/bin/ip netns exec no-vpn /usr/bin/nft -f /etc/nftables.conf
      ExecStop=/usr/local/bin/delete-no-vpn-namespace.sh
      [Install]
      WantedBy=multi-user.target      
    dest: /etc/systemd/system/no-vpn-network-namespace.service
    mode: 0644
  notify:
    - restart no-vpn network namespace

- name: enable service for no-VPN network namespace
  systemd:
    daemon_reload: true
    name: no-vpn-network-namespace.service
    enabled: true

- name: enable OpenVPN client service
  systemd:
    daemon_reload: true
    name: openvpn-client@{{vpn_name}}.service
    enabled: true

- name: register the fact that a VPN is enabled
  set_fact:
    is_vpn_used: true

### LOCAL COMMIT ⇒ ###
- name: commit local changes
  include_role: name=etckeeper.inc allow_duplicates=true tasks_from=local.yml
  vars:
    msg: OpenVPN
### ⇐ LOCAL COMMIT ###
- meta: flush_handlers