pxe-server/playbook/shopfloor-setup/Shopfloor/Register-CheckMachineNumberTask.ps1

# Register-CheckMachineNumberTask.ps1 - Register the two-task machine
# number flow at imaging time:
#
#   1. "Prompt Machine Number" - AtLogOn, BUILTIN\Users, Limited.
#      Shows InputBox + writes new number to a request file, then triggers
#      the SYSTEM task via schtasks /run.
#
#   2. "Apply Machine Number"  - on-demand only (no trigger), SYSTEM,
#      RunLevel Highest. Reads the request file, calls Update-MachineNumber
#      with full HKLM + ProgramData access, writes a result JSON, removes
#      the request file. No GUI - the Prompt task polls the result file
#      and displays the dialog.
#
# Replaces the old single-task design that ran as the logged-in user with
# pre-granted BUILTIN\Users HKLM ACLs (02-MachineNumberACLs.ps1). That
# approach was fragile (timing race with eDNC install, silent ACL skip)
# and a security hole (any user could write to the machine-identity reg
# key). With SYSTEM doing the actual writes, no ACL grants needed.
#
# Idempotent: safe to re-run. Existing tasks are overwritten.
#
# File kept named Register-CheckMachineNumberTask.ps1 (rather than
# Register-MachineNumberTasks.ps1) so Run-ShopfloorSetup's existing
# discovery doesn't need editing.

$ErrorActionPreference = 'Continue'

$logDir = 'C:\Logs\SFLD'
if (-not (Test-Path $logDir)) { New-Item -Path $logDir -ItemType Directory -Force | Out-Null }
$logFile = Join-Path $logDir 'register-checkmn.log'

function Write-RegLog {
    param([string]$Message)
    $line = '[{0}] [INFO] {1}' -f (Get-Date -Format 'yyyy-MM-dd HH:mm:ss'), $Message
    Add-Content -Path $logFile -Value $line -ErrorAction SilentlyContinue
    Write-Host $line
}

Write-RegLog '=== Register-CheckMachineNumberTask start ==='

$promptTaskName = 'Prompt Machine Number'
$applyTaskName  = 'Apply Machine Number'
$oldTaskName    = 'Check Machine Number'  # legacy, removed below

# Clean up the legacy single-task name from prior imaging cycles.
try {
    if (Get-ScheduledTask -TaskName $oldTaskName -ErrorAction SilentlyContinue) {
        Unregister-ScheduledTask -TaskName $oldTaskName -Confirm:$false -ErrorAction Stop
        Write-RegLog "Unregistered legacy task '$oldTaskName'"
    }
} catch { Write-RegLog "Could not unregister legacy '$oldTaskName': $_" }

# Only arm the tasks if the bay was imaged with the 9999 placeholder. If
# the tech entered a real machine number during PXE imaging it's already
# in C:\Enrollment\machine-number.txt; no prompt needed on first logon.
$mnFile = 'C:\Enrollment\machine-number.txt'
$mnAtImaging = '9999'
if (Test-Path -LiteralPath $mnFile) {
    $raw = (Get-Content -LiteralPath $mnFile -First 1 -ErrorAction SilentlyContinue)
    if ($raw) { $mnAtImaging = $raw.Trim() }
}
Write-RegLog "Imaging-time machine-number.txt = '$mnAtImaging'"
if ($mnAtImaging -ne '9999') {
    Write-RegLog "Machine number is real ('$mnAtImaging' != 9999). Not registering tasks."
    foreach ($t in @($promptTaskName, $applyTaskName)) {
        try {
            if (Get-ScheduledTask -TaskName $t -ErrorAction SilentlyContinue) {
                Unregister-ScheduledTask -TaskName $t -Confirm:$false -ErrorAction Stop
                Write-RegLog "Unregistered stale task '$t'"
            }
        } catch {}
    }
    Write-RegLog '=== Register-CheckMachineNumberTask end (no-op) ==='
    exit 0
}

# Resolve script paths. Prefer the staged shopfloor-setup tree on C:
# (where Run-ShopfloorSetup ran from); fall back to the same dir as this
# Register script if invoked standalone.
function Resolve-Script {
    param([string]$LeafName)
    $p = Join-Path $PSScriptRoot $LeafName
    if (Test-Path -LiteralPath $p) { return $p }
    $p = "C:\Enrollment\shopfloor-setup\Shopfloor\$LeafName"
    if (Test-Path -LiteralPath $p) { return $p }
    return $null
}

$promptScript = Resolve-Script 'Prompt-MachineNumber.ps1'
$applyScript  = Resolve-Script 'Apply-MachineNumber.ps1'
if (-not $promptScript) { Write-RegLog "Prompt-MachineNumber.ps1 not found - cannot register"; exit 1 }
if (-not $applyScript)  { Write-RegLog "Apply-MachineNumber.ps1 not found - cannot register";  exit 1 }
Write-RegLog "Prompt script: $promptScript"
Write-RegLog "Apply  script: $applyScript"

# --- Prompt task (user-context, GUI) ---
try {
    $action = New-ScheduledTaskAction `
        -Execute 'powershell.exe' `
        -Argument "-NoProfile -ExecutionPolicy Bypass -WindowStyle Normal -File `"$promptScript`""
    $trigger = New-ScheduledTaskTrigger -AtLogOn
    # Group SID S-1-5-32-545 = BUILTIN\Users (catches ShopFloor + support/admin
    # users that log in interactively). RunLevel Limited - no elevation; the
    # actual writes happen in the SYSTEM Apply task below.
    $principal = New-ScheduledTaskPrincipal -GroupId 'S-1-5-32-545' -RunLevel Limited
    $settings  = New-ScheduledTaskSettingsSet -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries -StartWhenAvailable -ExecutionTimeLimit (New-TimeSpan -Minutes 5)
    Register-ScheduledTask -TaskName $promptTaskName -Action $action -Trigger $trigger -Principal $principal -Settings $settings -Force -ErrorAction Stop | Out-Null
    Write-RegLog "Registered scheduled task '$promptTaskName' (AtLogOn, BUILTIN\Users, Limited)"
} catch {
    Write-RegLog "FAILED to register '$promptTaskName': $_"
    exit 1
}

# --- Apply task (SYSTEM, on-demand) ---
try {
    $action = New-ScheduledTaskAction `
        -Execute 'powershell.exe' `
        -Argument "-NoProfile -ExecutionPolicy Bypass -WindowStyle Hidden -File `"$applyScript`""
    # No trigger - the Prompt task starts this via schtasks /run /tn.
    $principal = New-ScheduledTaskPrincipal -UserId 'SYSTEM' -LogonType ServiceAccount -RunLevel Highest
    $settings  = New-ScheduledTaskSettingsSet -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries -StartWhenAvailable -ExecutionTimeLimit (New-TimeSpan -Minutes 10)
    Register-ScheduledTask -TaskName $applyTaskName -Action $action -Principal $principal -Settings $settings -Force -ErrorAction Stop | Out-Null
    Write-RegLog "Registered scheduled task '$applyTaskName' (on-demand, SYSTEM, Highest)"

    # Default SDDL on a SYSTEM-owned task only grants Admins + SYSTEM
    # FullAccess - BUILTIN\Users can't see or run it via schtasks /run.
    # Add an ACE granting BUILTIN\Users GenericRead + GenericExecute so the
    # user-context Prompt task can trigger this Apply task on demand. They
    # still can't modify/delete it - only read+execute.
    try {
        $svc = New-Object -ComObject Schedule.Service
        $svc.Connect()
        $taskObj = $svc.GetFolder('\').GetTask($applyTaskName)
        # GenericRead = 0x80000000 (GR), GenericExecute = 0x20000000 (GX)
        # BU = BUILTIN\Users
        $newSd = 'O:BAG:BAD:(A;;FA;;;BA)(A;;FA;;;SY)(A;;GRGX;;;BU)'
        # SetSecurityDescriptor flag 0 = default, persists DACL change.
        $taskObj.SetSecurityDescriptor($newSd, 0)
        Write-RegLog "Granted BUILTIN\Users GR+GX on '$applyTaskName' (so Limited users can schtasks /run)"
    } catch {
        Write-RegLog "FAILED to set task SDDL on '$applyTaskName': $_ (Limited users may not be able to trigger Apply)"
    }
} catch {
    Write-RegLog "FAILED to register '$applyTaskName': $_"
    exit 1
}

Write-RegLog '=== Register-CheckMachineNumberTask end ==='
exit 0