From a1e941276ec9e89931e2b8b8048e0c4cc8183361 Mon Sep 17 00:00:00 2001
From: "Michael N. Lipp" <mnl@mnl.de>
Date: Wed, 26 Feb 2025 21:59:38 +0100
Subject: [PATCH] Working login script.

---
 dev-example/vmop-agent/vmop-agent | 103 ++++++++++++++++++++++++++++--
 webpages/vm-operator/pools.md     |  65 +++++++++++++++++++
 2 files changed, 162 insertions(+), 6 deletions(-)
 create mode 100644 webpages/vm-operator/pools.md

diff --git a/dev-example/vmop-agent/vmop-agent b/dev-example/vmop-agent/vmop-agent
index b3157b9..ad5f427 100755
--- a/dev-example/vmop-agent/vmop-agent
+++ b/dev-example/vmop-agent/vmop-agent
@@ -1,19 +1,110 @@
 #!/usr/bin/bash
 
-hostSerial="/dev/virtio-ports/org.jdrupes.vmop_agent.0"
+while [ "$#" -gt 0 ]; do
+  case "$1" in
+    --path) shift; ttyPath="$1";;
+    --path=*) IFS='=' read -r option value <<< "$1"; ttyPath="$value";;
+  esac
+  shift
+done
 
-if [ ! -w "$hostSerial" ]; then
-  echo >&2 "Device $hostSerial not writable"
+ttyPath="${ttyPath:-/dev/virtio-ports/org.jdrupes.vmop_agent.0}"
+
+if [ ! -w "$ttyPath" ]; then
+  echo >&2 "Device $ttyPath not writable"
   exit 1
 fi
 
-if ! exec {con}<>"$hostSerial"; then
-  echo >&2 "Cannot open device $hostSerial"
+if ! exec {con}<>"$ttyPath"; then
+  echo >&2 "Cannot open device $ttyPath"
   exit 1
 fi
 
+temperr=$(mktemp)
+clear >/dev/tty1
 echo >&${con} "220 Hello"
 
+createUser() {
+  local missing=$1
+  local uid
+  local userHome="/home/$missing"
+  local createOpts=""
+  if [ -d "$userHome" ]; then
+    uid=$(ls -ldn "$userHome" | head -n 1 | awk '{print $3}')
+    createOpts="--no-create-home"
+  else
+    uid=$(ls -ln "/home" | tail -n +2 | awk '{print $3}' | sort | tail -1)
+    uid=$(( $uid + 1 ))
+    if [ $uid -lt 1000 ]; then
+      uid=1000
+    fi
+    createOpts="--create-home"
+  fi
+  groupadd -g $uid $missing
+  useradd $missing -u $uid -g $uid $createOpts
+}
+
+doLogin() {
+  user=$1
+  if [ "$user" = "root" ]; then
+    echo >&${con} "504 Won't log in root"
+    return
+  fi
+  uid=$(id -u ${user} 2>/dev/null)
+  if [ $? != 0 ]; then
+    ( flock 200
+      createUser ${user}
+    ) 200>/home/.gen-uid-lock
+    uid=$(id -u ${user} 2>/dev/null)
+    if [ $? != 0 ]; then
+      echo >&${con} "451 Cannot determine uid"
+      return
+    fi
+  fi
+  systemd-run 2>$temperr \
+    --unit vmop-user-desktop --uid=$uid --gid=$uid \
+    --working-directory="/home/$user" -p TTYPath=/dev/tty1 \
+    -p PAMName=login -p StandardInput=tty -p StandardOutput=journal \
+    -E XDG_RUNTIME_DIR="/run/user/$uid" \
+    -p ExecStartPre="/usr/bin/chvt 1" \
+    dbus-run-session -- gnome-shell --display-server --wayland
+  if [ $? -eq 0 ]; then
+    echo >&${con} "201 User logged in"
+  else
+    echo >&${con} "451 $(<${temperr})"
+  fi
+}
+
+attemptLogout() {
+  systemctl status vmop-user-desktop > /dev/null 2>&1
+  if [ $? = 0 ]; then
+    systemctl stop vmop-user-desktop
+    echo >&${con} "102 Desktop stopped"
+  fi
+}
+
+doLogout() {
+  attemptLogout
+  loginctl -j | jq -r '.[] | select(.tty=="tty1") | .session' \
+  | while read sid; do
+    loginctl kill-session $sid
+  done
+  echo >&${con} "202 User logged out"
+}
+
 while read line <&${con}; do
-  true
+  case $line in
+  "login "*) IFS=' ' read -ra args <<< "$line"; doLogin ${args[1]};;
+  logout) doLogout;;
+  esac
 done
+
+onExit() {
+  attemptLogout
+  if [ -n "$temperr" ]; then
+    rm -f $temperr
+  fi
+  echo >&${con} "240 Quit"
+}
+
+trap onExit EXIT
diff --git a/webpages/vm-operator/pools.md b/webpages/vm-operator/pools.md
new file mode 100644
index 0000000..290d0fd
--- /dev/null
+++ b/webpages/vm-operator/pools.md
@@ -0,0 +1,65 @@
+---
+title: "VM-Operator: VM pools — assigning VMs to users dynamically"
+layout: vm-operator
+---
+
+# VM Pools
+
+*Since 4.0.0*
+
+## Prepare the VM
+
+### Shared file system
+
+Mount a shared file system as home file system on all VMs in the pool.
+
+### Restrict access
+
+The only possibility to access the VMs should be via a desktop started by
+the VM-Operator.
+
+ * Disable the display manager.
+ 
+   ```console
+   # systemctl disable gdm
+   # systemctl stop gdm
+   ```
+   
+ * Disable `getty` on tty1.
+ 
+   ```console
+   # systemctl mask getty@tty1
+   # systemctl stop getty@tty1
+   ```
+   
+   You can, of course, disable `getty` completely. If you do this, make sure
+   that you can still access your master VM through `ssh`, else you have
+   locked yourself out.
+   
+ * Prevent suspend/hibernate, because it will lock the VM.
+ 
+   ```console
+   # systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target
+   ```
+ 
+### Install the VM-Operator agent
+
+The VM-Operator agent runs as a systemd service. Sample configuration
+files can be found
+[here](https://github.com/mnlipp/VM-Operator/tree/main/dev-example/vmop-agent).
+Copy 
+
+  * `99-vmop-agent.rules` to `/usr/local/lib/udev/rules.d/99-vmop-agent.rules`,
+  * `vmop-agent` to `/usr/local/libexec/vmop-agent` and
+  * `vmop-agent.service` to `/usr/local/lib/systemd/system/vmop-agent.service`.
+
+Note that some of the target directories do not exist by default and have to
+be created first. Don't forget to run `restorecon` on systems with SELinux.
+
+Enable everything:
+
+```console
+# udevadm control --reload-rules
+# systemctl enable vmop-agent
+# udevadm trigger
+ ```