Enable firewall activation for exam-mode

For working exam-mode we need to block direct internet access by firewall.
Users have to use squid-proxy on firewall, which can be disabled for exam-users.
To allow VM-traffic (anonymous user), we use a local squid server with users
kerberos-ticket to authenticate on the parent squid.

When using VMs on teacherdevices offsite, the local squid has to use direct internet access.
So we need two squid configs. When switching between offsite and onsite,
the squid has to be restartet with corresponding config.

roles/lmn_vm/files/usersquid.service

@@ -0,0 +1,10 @@
+[Unit]
+Description=Run squid in usermode using user kerberos ticket
+
+[Service]
+Type=simple
+ExecStart=/usr/local/bin/startusersquid.sh
+Restart=on-failure
+
+#[Install]
+#WantedBy=default.target

roles/lmn_vm/files/vm-run

@@ -287,11 +287,7 @@ fi
 
 VM_NAME=$1
 
-# check, if we have to start squid
-if ! killall -s 0 squid; then
-    echo "starting squid."
-    /usr/sbin/squid -f /etc/squid/squid-usermode.conf
-fi
+systemctl --user restart usersquid.service &
 
 # check, if persistent VM is really wanted
 if [[ "${PERSISTENT}" == 1 ]] && [[ ! -f "${VM_DIR_PERSISTENT}/${VM_NAME}.qcow2" ]]; then

roles/lmn_vm/handlers/main.yml

@@ -3,6 +3,11 @@
     name: libvirtd.service
   listen: reload libvirtd
 
+- name: Just force systemd to reread configs
+  ansible.builtin.systemd_service:
+    daemon_reload: true
+  listen: daemon reload
+
 - name: Run update-desktop-database
   command: update-desktop-database "{{ item }}"
   loop:

roles/lmn_vm/tasks/main.yml

@@ -147,9 +147,25 @@
 
 - name: Deploy squid user mode configuration
   template:
-    src: squid-usermode.conf.j2
-    dest: /etc/squid/squid-usermode.conf
+    src: "{{ item }}.j2"
+    dest: "/etc/squid/{{ item }}"
     mode: '0644'
+  loop:
+    - squid-usermode.conf
+    - squid-usermode-external.conf
+
+- name: Deploy startusersquid script
+  template:
+    src: startusersquid.sh.j2
+    dest: /usr/local/bin/startusersquid.sh
+    mode: '0755'
+  notify: daemon reload
+
+- name: Provide usersquid service
+  copy:
+    src: usersquid.service
+    dest: /etc/systemd/user/usersquid.service
+    mode: 0644
 
 - name: Deploy sudo configurations
   copy:

roles/lmn_vm/templates/squid-usermode-external.conf.j2

@@ -0,0 +1,11 @@
+acl local-servers dstdomain .{{ domain }}
+cache_peer firewall.{{ domain }} parent 3128 0 no-query default login=NEGOTIATE auth-no-keytab
+never_direct deny local-servers
+always_direct allow all
+#access_log stdio:/tmp/access.log squid
+access_log none
+cache_log /dev/null
+logfile_rotate 0
+pid_filename none
+http_port 192.168.122.1:3128
+http_access allow all

roles/lmn_vm/templates/squid-usermode.conf.j2

@@ -1,7 +1,7 @@
 acl local-servers dstdomain .{{ domain }}
 cache_peer firewall.{{ domain }} parent 3128 0 no-query default login=NEGOTIATE auth-no-keytab
 never_direct deny local-servers
-always_direct allow all
+never_direct allow all
 #access_log stdio:/tmp/access.log squid
 access_log none
 cache_log /dev/null