kik-website/server/scripts/install_restore_task.ps1
Zebreus 5f9796cc11 Keep the shell server working over a deployment
The server logs to a file that was overwritten on every start, so an outage left no
trace. It is appended to now, and rotated when it grows past a megabyte.

The cleanup job restarts the server when nobody is connected and when the server does
not listen at all: it comes back by itself if it died, it takes over a server that was
left behind, and it picks up the programs that were just restored. A session that is
open keeps the port and the runtime, so the server is not restarted then.

A deployment does not restart the server. It runs in a session, and that session keeps
the port, so a server that starts during a deployment cannot bind it. The deployment
only writes the configuration; the cleanup job applies it.

The runtime of the installation is not protected any more. A program and the shell
that starts it have to use the same runtime DLL, or the program does not run at all,
so the login path now uses the one in /usr/bin, next to the user's own programs. What
is protected instead is that it is the one the package says it is: pacman checks the
files of msys2-runtime and the cleanup job puts the package back if it was changed.

Only keys may log in over SSH now, and Remote Desktop needs network level
authentication. Only the administrator may log in over it: the user of the website is
in no group that may.

Co-Authored-By: Claude Opus <noreply@anthropic.com>
2026-10-27 02:46:45 +01:00

500 lines
29 KiB
PowerShell

# Sets up the shell server so the website's root user can install packages with pacman, while the basic user
# journey - logging in with the key, the prompt, the home directory and the four text files - cannot be broken.
#
# The whole MSYS2 installation belongs to the root user: they may write everywhere and run pacman. The login path
# the journey depends on - the sshd, the login shell zsh and cat - is kept as a protected copy in C:\msys2\opt\kik
# that only SYSTEM and the administrators may write. The sshd runs as SYSTEM from that copy (the scheduled task
# "KiK sshd"), so replacing /usr/bin/sshd does not touch the running server. A second scheduled task,
# "KiK restore shell files", puts the home directory, the four texts and the protected copy back every 30 minutes.
#
# opt/kik works because its MSYS2 runtime resolves the same installation root (C:\msys2) as /usr/bin, so the login
# shell and the user's own tools share one cygwin runtime. A separate second installation cannot: two runtimes in
# one process tree break each other's file descriptors, and pacman then cannot even lock its database.
#
# Run this in an elevated PowerShell on the server, with this script and the ../resources directory next to it:
# powershell -ExecutionPolicy Bypass -File .\install_restore_task.ps1
# Remove the tasks and the protected copy again (the installation goes back to a normal cygrunsrv sshd) with:
# powershell -ExecutionPolicy Bypass -File .\install_restore_task.ps1 -Uninstall
[CmdletBinding()]
param(
[string]$HomeDir = 'C:\msys2\home\root',
[switch]$Uninstall
)
$ErrorActionPreference = 'Stop'
$msys = 'C:\msys2'
$kik = "$msys\opt\kik"
$installDir = 'C:\ProgramData\kik-restore'
$copiesDir = Join-Path $installDir 'files'
$binDir = Join-Path $installDir 'bin'
$sshdBat = Join-Path $installDir 'run-sshd.bat'
$restoreTask = 'KiK restore shell files'
$sshdTask = 'KiK sshd'
$service = 'msys2-sshd'
# The programs the journey needs, kept out of the user's reach. sshd-session and sshd-auth are the per-connection
# helpers OpenSSH 10 re-executes; zsh is the login shell; cat reads the four texts.
$loginBinaries = "$msys\usr\bin\sshd.exe", "$msys\usr\lib\ssh\sshd-session.exe", "$msys\usr\lib\ssh\sshd-auth.exe",
"$msys\usr\bin\zsh.exe", "$msys\usr\bin\cat.exe"
# The runtime is not among them: a program and the shell that starts it have to use the same runtime, or the
# program does not run at all. The login path therefore uses the one in /usr/bin, and the user may replace it -
# pacman checks that it is the one the package says it is, and the cleanup job puts it back if it is not.
$runtimeFiles = '/usr/bin/msys-2.0.dll'
# The copies the task restores from and the script it runs both live in $installDir, which only SYSTEM and the
# administrators may read or write.
$restoreScript = @'
# Puts the shell server back into shape and keeps the protected login path in place. Runs as SYSTEM every 30 minutes
# and at startup; the root user can neither stop it nor change the copies it restores from.
param([string]$HomeDir = 'C:\msys2\home\root')
$msys = 'C:\msys2'
$kik = "$msys\opt\kik"
$log = Join-Path $PSScriptRoot 'restore.log'
$copies = Join-Path $PSScriptRoot 'files\home'
$binDir = Join-Path $PSScriptRoot 'bin'
# The account of the shell server's root user, whose id the files in its home directory belong to.
$passwd = Get-Content "$msys\etc\passwd" -ErrorAction SilentlyContinue | Where-Object { $_ -like 'root:*' }
$sid = if ($passwd) { ($passwd -split ':')[4].Split(',')[-1] }
$system = New-Object System.Security.Principal.SecurityIdentifier('S-1-5-18')
$admins = New-Object System.Security.Principal.SecurityIdentifier('S-1-5-32-544')
function Write-Log($message) {
"$(Get-Date -Format s) $message" | Out-File -FilePath $log -Append
}
# Removes a file, a directory or a link, but never what a link points to.
function Remove-Anything($path) {
$item = Get-Item -LiteralPath $path -Force
if ($item.Attributes -band [IO.FileAttributes]::ReparsePoint) {
if ($item.PSIsContainer) { [IO.Directory]::Delete($path) } else { [IO.File]::Delete($path) }
} elseif ($item.PSIsContainer) {
Remove-Item -LiteralPath $path -Recurse -Force
} else {
Remove-Item -LiteralPath $path -Force
}
}
# A path that only SYSTEM and the administrators own. $userRights is what the root user may do: 'None' (the ssh keys
# and config), 'Read' (the account database) or 'ReadAndExecute' (the login programs it has to run).
function Set-LockedAcl($path, $forDirectory, $userRights) {
$acl = Get-Acl -LiteralPath $path
$acl.SetAccessRuleProtection($true, $false)
foreach ($rule in @($acl.Access)) { [void]$acl.RemoveAccessRuleSpecific($rule) }
$acl.SetOwner($admins)
$inherit = if ($forDirectory) { 'ContainerInherit,ObjectInherit' } else { 'None' }
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule($system, 'FullControl', $inherit, 'None', 'Allow')))
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule($admins, 'FullControl', $inherit, 'None', 'Allow')))
if ($userRights -ne 'None' -and $sid) {
$user = New-Object System.Security.Principal.SecurityIdentifier($sid)
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule($user, $userRights, $inherit, 'None', 'Allow')))
}
Set-Acl -LiteralPath $path -AclObject $acl
}
# The website logs in with a key in the authorized_keys of the user. The user may keep keys of their own, so only
# the key of the website is put back.
function Restore-Keys($target, $source) {
$required = @(Get-Content -LiteralPath $source | Where-Object { $_.Trim() })
$blobs = $required | ForEach-Object { ($_ -split '\s+')[1] }
$keys = @()
if (Test-Path -LiteralPath $target) {
$keys = @(Get-Content -LiteralPath $target | Where-Object { $_.Trim() -and $blobs -notcontains ($_ -split '\s+')[1] })
}
[IO.File]::WriteAllText($target, (($keys + $required) -join "`n") + "`n")
}
# The shell configuration and the key the website logs in with must not change, the four texts may be edited.
$readOnly = '.zshrc', '.zshenv', 'authorized_keys'
# The permissions of the home directory and of the files in it that have to stay: the user may read them and write
# the ones that may change, and delete their own files, but not the home directory itself and not the files the
# website needs. Only SYSTEM and the administrators own them, so the user cannot take the permissions away again.
function Set-HomeAcl($path, $forDirectory, $writable) {
if (-not $sid) { return }
try {
$user = New-Object System.Security.Principal.SecurityIdentifier($sid)
$acl = Get-Acl -LiteralPath $path
$acl.SetAccessRuleProtection($true, $false)
foreach ($rule in @($acl.Access)) { [void]$acl.RemoveAccessRuleSpecific($rule) }
$acl.SetOwner($admins)
$none = [System.Security.AccessControl.InheritanceFlags]::None
$children = [System.Security.AccessControl.InheritanceFlags]::ContainerInherit -bor [System.Security.AccessControl.InheritanceFlags]::ObjectInherit
$inheritOnly = [System.Security.AccessControl.PropagationFlags]::InheritOnly
$full = [System.Security.AccessControl.FileSystemRights]::FullControl
$some = [System.Security.AccessControl.FileSystemRights]::ReadAndExecute -bor [System.Security.AccessControl.FileSystemRights]::Write
$read = [System.Security.AccessControl.FileSystemRights]::ReadAndExecute
$inherit = if ($forDirectory) { $children } else { $none }
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule -ArgumentList $system, $full, $inherit, 'None', 'Allow'))
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule -ArgumentList $admins, $full, $inherit, 'None', 'Allow'))
$userRights = if ($writable) { $some } else { $read }
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule -ArgumentList $user, $userRights, $none, 'None', 'Allow'))
if ($forDirectory) {
# the files in it are the user's own, they may delete them
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule -ArgumentList $user, $full, $children, $inheritOnly, 'Allow'))
}
Set-Acl -LiteralPath $path -AclObject $acl
} catch {
Write-Log "the permissions of $path are not set: $_"
}
}
# The home directory is the one from /etc/passwd, which the user cannot change, but which they can delete. A new one
# gets MSYS2's default files from /etc/skel, which MSYS2 itself only copies into a home that does not exist yet.
function New-Home($path) {
New-Item -ItemType Directory -Path $path | Out-Null
Set-HomeAcl $path $true $true
Get-ChildItem -LiteralPath "$msys\etc\skel" -Force | Copy-Item -Destination $path -Recurse -Force
}
# The server is stopped and started again when nobody is connected: it picks up the programs that are restored
# just now, and it comes back by itself if it died. It has to be stopped before the copies are made, because a
# running server holds its programs open and they cannot be replaced.
#
# Stopping the task does not take the server with it, so its processes are killed by hand and the task is waited
# for: it ignores a new instance while one is running, so a start would be dropped.
function Stop-Sshd {
Stop-ScheduledTask -TaskName 'KiK sshd' -ErrorAction SilentlyContinue
Get-CimInstance Win32_Process -Filter "Name='cmd.exe'" | Where-Object { $_.CommandLine -match 'cmd\.exe\s+/c\s+"?C:\\ProgramData\\kik-restore\\run-sshd\.bat' } |
ForEach-Object { Stop-Process -Id $_.ProcessId -Force -ErrorAction SilentlyContinue }
Get-Process -Name sshd -ErrorAction SilentlyContinue | Stop-Process -Force
$waited = 0
while ((Get-ScheduledTask -TaskName 'KiK sshd').State -ne 'Ready' -and $waited -lt 30) { Start-Sleep 1; $waited++ }
$waited = 0
while ((Get-NetTCPConnection -LocalPort 22 -State Listen -ErrorAction SilentlyContinue) -and $waited -lt 30) { Start-Sleep 1; $waited++ }
}
# The server is started again and waited for: a deployment or a crash must never leave the site without a shell.
function Start-Sshd {
Start-ScheduledTask -TaskName 'KiK sshd'
$waited = 0
while (-not (Get-NetTCPConnection -LocalPort 22 -State Listen -ErrorAction SilentlyContinue) -and $waited -lt 30) { Start-Sleep 1; $waited++ }
return [bool](Get-NetTCPConnection -LocalPort 22 -State Listen -ErrorAction SilentlyContinue)
}
$netError = $null
$connections = @(Get-NetTCPConnection -LocalPort 22 -ErrorAction SilentlyContinue -ErrorVariable netError)
$sessions = @(Get-Process -Name 'sshd-session' -ErrorAction SilentlyContinue)
# A session that is open keeps the port and the runtime, so the server is only restarted when there is none: it
# comes back by itself if it died, it takes over a server that was left behind, and it picks up the programs that
# were just restored. A query that fails is not a reason to disturb a session.
$busy = @($connections | Where-Object { $_.State -eq 'Established' }).Count -gt 0 -or $sessions.Count -gt 0
$restart = -not $netError -and -not $busy
if ($restart) {
Stop-Sshd
# The runtime of the installation belongs to the user's programs and is not protected: a program and the shell
# that starts it have to use the same one, or the program does not run at all. What has to be protected is that
# it is the one the package says it is, because the server runs as SYSTEM.
Remove-Item "$kik\msys-2.0.dll" -Force -ErrorAction SilentlyContinue
& "$msys\usr\bin\pacman.exe" -Qkk msys2-runtime 2>&1 | Out-Null
if ($LASTEXITCODE -ne 0) {
& "$msys\usr\bin\pacman.exe" -S --noconfirm --overwrite '*' msys2-runtime 2>&1 | Out-Null
Write-Log 'restored the runtime of the installation'
}
}
try {
# The protected login path: the copy the sshd and the login shell run from. The user cannot write it, so even
# after they replace or remove their own copies in /usr/bin the server and the journey keep working. The trusted
# originals are in bin\; anything missing from opt/kik is put back.
if (Test-Path -LiteralPath $binDir) {
if (-not (Test-Path -LiteralPath $kik)) { New-Item -ItemType Directory -Path $kik | Out-Null }
foreach ($file in Get-ChildItem -LiteralPath $binDir -File -Force | Where-Object { $_.Name -ne 'msys-2.0.dll' }) {
$target = Join-Path $kik $file.Name
try {
if (-not (Test-Path -LiteralPath $target) -or (Get-Item -LiteralPath $target -Force).Length -ne $file.Length) {
Copy-Item -LiteralPath $file.FullName -Destination $target -Force
Write-Log "restored opt/kik/$($file.Name)"
}
} catch {
# a running server holds its programs open; they are replaced in one of the next runs
Write-Log "failed opt/kik/$($file.Name) : $_"
}
}
New-Item -ItemType Directory -Force -Path "$kik\dev\shm", "$kik\dev\mqueue" | Out-Null
Set-LockedAcl $kik $true 'ReadAndExecute'
# /dev is scratch: the user may write it so POSIX shared memory works, the rest of opt/kik stays read-only
if ($sid) { icacls "$kik\dev" /grant "*${sid}:(OI)(CI)M" | Out-Null }
}
# The account database and the ssh keys and config the SYSTEM server reads: the user may read passwd (programs
# map ids through it) but change none of it, and has no business in /etc/ssh at all.
$rootShell = '/opt/kik/zsh.exe'
$pw = "$msys\etc\passwd"
$lines = Get-Content $pw
if ($lines | Where-Object { $_ -match '^root:' -and $_ -notmatch ':/opt/kik/zsh\.exe$' }) {
($lines | ForEach-Object { if ($_ -match '^root:') { $_ -replace ':[^:]*$', ":$rootShell" } else { $_ } }) | Set-Content $pw -Encoding ascii
Write-Log 'set the root login shell to the protected zsh'
}
Set-LockedAcl $pw $false 'Read'
if (Test-Path "$msys\etc\ssh") { Set-LockedAcl "$msys\etc\ssh" $true 'None' }
# The whole installation otherwise belongs to the user, so pacman can write it. The home directory keeps its own
# protected permissions because they are set without inheritance.
if ($sid) { icacls $msys /grant "*${sid}:(OI)(CI)F" | Out-Null }
} catch {
Write-Log "the protected login path is not fully in place: $_"
}
if (-not (Test-Path -LiteralPath $HomeDir)) {
New-Home $HomeDir
Write-Log "created $HomeDir"
} elseif ((Get-Item -LiteralPath $HomeDir -Force).Attributes -band [IO.FileAttributes]::ReparsePoint) {
Remove-Anything $HomeDir
New-Home $HomeDir
Write-Log "replaced the link $HomeDir"
} else {
Set-HomeAcl $HomeDir $true $true
}
foreach ($copy in Get-ChildItem -LiteralPath $copies -Recurse -File -Force) {
$target = Join-Path $HomeDir $copy.FullName.Substring($copies.Length).TrimStart('\')
try {
$dir = Split-Path -Parent $target
if ((Test-Path -LiteralPath $dir) -and -not (Get-Item -LiteralPath $dir -Force).PSIsContainer) {
Remove-Anything $dir
}
if (-not (Test-Path -LiteralPath $dir)) { New-Item -ItemType Directory -Path $dir | Out-Null }
Set-HomeAcl $dir $true $true
if (Test-Path -LiteralPath $target) {
$item = Get-Item -LiteralPath $target -Force
if ($item.PSIsContainer -or $item.Attributes -band [IO.FileAttributes]::ReparsePoint) {
# anything but a file is replaced, so that the files are always the text files they should be
Remove-Anything $target
} else {
# the user may have locked the file; taking it back lets us write it
takeown /f $target /a | Out-Null
}
}
if ($copy.Name -eq 'authorized_keys') {
Restore-Keys $target $copy.FullName
} else {
Copy-Item -LiteralPath $copy.FullName -Destination $target -Force
}
Set-HomeAcl $target $false ($readOnly -notcontains $copy.Name)
# the user may have made the file read-only for themselves, the four texts are theirs to change
(Get-Item -LiteralPath $target -Force).IsReadOnly = $false
Write-Log "restored $($copy.Name)"
} catch {
Write-Log "failed $($copy.Name) : $_"
}
}
if ($restart) {
if (Start-Sshd) { Write-Log 'restarted the sshd' } else { Write-Log 'the sshd does not listen on port 22' }
}
'@
if (-not ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)) {
throw 'Run this in an elevated PowerShell.'
}
$system = New-Object System.Security.Principal.SecurityIdentifier('S-1-5-18')
$admins = New-Object System.Security.Principal.SecurityIdentifier('S-1-5-32-544')
$passwd = Get-Content "$msys\etc\passwd" -ErrorAction SilentlyContinue | Where-Object { $_ -like 'root:*' }
if (-not $passwd) { throw "No root user in $msys\etc\passwd." }
$sid = ($passwd -split ':')[4].Split(',')[-1]
# A previous install may have locked opt/kik, the account database and the ssh keys. The administrators keep
# full control over them, so reset the permissions to inherited now and let this run write freely; the restore
# task locks everything again at the end.
$prevEA = $ErrorActionPreference; $ErrorActionPreference = 'SilentlyContinue'
foreach ($p in "$msys\opt\kik", "$msys\etc\ssh", "$msys\etc\passwd") {
if (Test-Path -LiteralPath $p) { icacls $p /reset /t /q | Out-Null }
}
Get-ChildItem "$msys\etc\ssh", "$msys\etc\passwd" -Force | ForEach-Object { try { $_.IsReadOnly = $false } catch {} }
$ErrorActionPreference = $prevEA
function Set-LockedAcl($path, $forDirectory, $userRights) {
$acl = Get-Acl -LiteralPath $path
$acl.SetAccessRuleProtection($true, $false)
foreach ($rule in @($acl.Access)) { [void]$acl.RemoveAccessRuleSpecific($rule) }
$acl.SetOwner($admins)
$inherit = if ($forDirectory) { 'ContainerInherit,ObjectInherit' } else { 'None' }
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule($system, 'FullControl', $inherit, 'None', 'Allow')))
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule($admins, 'FullControl', $inherit, 'None', 'Allow')))
if ($userRights -ne 'None') {
$user = New-Object System.Security.Principal.SecurityIdentifier($sid)
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule($user, $userRights, $inherit, 'None', 'Allow')))
}
Set-Acl -LiteralPath $path -AclObject $acl
}
# The DLLs an MSYS2 program loads, as Windows paths under C:\msys2.
function Get-Libraries($program) {
$paths = @()
$posix = ($program -replace '^C:\\msys2', '') -replace '\\', '/'
foreach ($line in & "$msys\usr\bin\ldd.exe" $posix 2>$null) {
foreach ($m in [regex]::Matches($line, '/usr/[^\s]+\.dll')) { $paths += $m.Value }
}
$paths | Select-Object -Unique | Where-Object { $_ -notin $runtimeFiles } | ForEach-Object { $msys + ($_ -replace '/', '\') }
}
if ($Uninstall) {
foreach ($t in $restoreTask, $sshdTask) { Unregister-ScheduledTask -TaskName $t -Confirm:$false -ErrorAction SilentlyContinue }
if (Test-Path -LiteralPath $installDir) { Remove-Item -LiteralPath $installDir -Recurse -Force }
if (Test-Path -LiteralPath $kik) {
icacls $kik /reset /t /q 2>$null | Out-Null
Remove-Item -LiteralPath $kik -Recurse -Force -ErrorAction SilentlyContinue
}
# the installation's own cygrunsrv sshd takes over again
$pw = "$msys\etc\passwd"
(Get-Content $pw | ForEach-Object { if ($_ -match '^root:') { $_ -replace ':[^:]*$', ':/usr/bin/zsh' } else { $_ } }) | Set-Content $pw -Encoding ascii
icacls $pw /reset | Out-Null
if (Test-Path "$msys\etc\ssh") { icacls "$msys\etc\ssh" /reset /t /q 2>$null | Out-Null }
Set-Service $service -StartupType Automatic -ErrorAction SilentlyContinue
Start-Service $service -ErrorAction SilentlyContinue
Write-Host "Removed the tasks and $installDir; the $service service serves ssh again."
return
}
$resources = Join-Path $PSScriptRoot '..\resources'
if (-not (Get-ChildItem -LiteralPath $resources -Recurse -File -Force)) { throw "No files in $resources." }
$prepared = Get-Item -LiteralPath $installDir -Force -ErrorAction SilentlyContinue
if ($prepared -and $prepared.Attributes -band [IO.FileAttributes]::ReparsePoint) { throw "$installDir is a link, refusing to install." }
New-Item -ItemType Directory -Force -Path $copiesDir, $binDir | Out-Null
# Only SYSTEM and the administrators may read or write the copies, the trusted login programs and the scripts.
$acl = New-Object System.Security.AccessControl.DirectorySecurity
$acl.SetAccessRuleProtection($true, $false)
foreach ($owner in $system, $admins) {
$acl.AddAccessRule((New-Object System.Security.AccessControl.FileSystemAccessRule($owner, 'FullControl', 'ContainerInherit,ObjectInherit', 'None', 'Allow')))
}
$acl.SetOwner($admins)
Set-Acl -LiteralPath $installDir -AclObject $acl
foreach ($item in Get-ChildItem -LiteralPath $installDir -Recurse -Force) {
if ($item.Attributes -band [IO.FileAttributes]::ReparsePoint) { throw "$($item.FullName) is a link, refusing to install." }
}
Remove-Item -LiteralPath $copiesDir -Recurse -Force
New-Item -ItemType Directory -Force -Path $copiesDir | Out-Null
Copy-Item -Path (Join-Path $resources '*') -Destination $copiesDir -Recurse -Force
# The Administrator logs in with the key of the people who deploy, which is in the resources. The keys that are
# already there stay.
$adminKeys = 'C:\Users\Administrator\.ssh\authorized_keys'
$required = @(Get-Content -LiteralPath (Join-Path $resources 'admin\.ssh\authorized_keys') | Where-Object { $_.Trim() })
$keys = @()
if (Test-Path -LiteralPath $adminKeys) { $keys = @(Get-Content -LiteralPath $adminKeys | Where-Object { $_.Trim() }) }
if (-not ($keys | Where-Object { ($_ -split '\s+')[1] -eq ($required[0] -split '\s+')[1] })) {
New-Item -ItemType Directory -Force -Path (Split-Path -Parent $adminKeys) | Out-Null
[IO.File]::WriteAllText($adminKeys, (($keys + $required) -join "`n") + "`n")
}
[IO.File]::WriteAllText((Join-Path $installDir 'restore.ps1'), $restoreScript)
# The trusted login programs: the sshd, its helpers, the login shell and cat, with every DLL they load. The restore
# task puts these into opt/kik, which the user cannot write.
Remove-Item "$binDir\*" -Force -ErrorAction SilentlyContinue
$files = @{}
foreach ($b in $loginBinaries) {
if (-not (Test-Path -LiteralPath $b)) { throw "$b does not exist." }
$files[$b] = $true
foreach ($lib in Get-Libraries $b) { $files[$lib] = $true }
}
foreach ($f in $files.Keys) { Copy-Item -LiteralPath $f -Destination $binDir -Force }
# Remote Desktop is the way in for the administrator, and the port is open to the internet. It needs network level
# authentication, so that a scanner cannot get a session before it has proven that it knows the password.
$rdpTcp = 'HKLM:\SYSTEM\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp'
$nla = (Get-ItemProperty -Path $rdpTcp -Name UserAuthentication).UserAuthentication
Set-ItemProperty -Path $rdpTcp -Name UserAuthentication -Value 1 -Type DWord
if ($nla -ne 1) {
# the setting only counts when the service starts again, which drops the sessions that are open
Restart-Service TermService -Force
}
# Only the administrator may log in over Remote Desktop. The user of the website is in no group that may log in
# over it, and it must never be an administrator - that is taken away if it somehow got there.
$rootAccount = Get-LocalUser -Name 'root' -ErrorAction SilentlyContinue
if ($rootAccount) {
foreach ($group in 'Administrators', 'Remote Desktop Users') {
$member = Get-LocalGroupMember $group -ErrorAction SilentlyContinue | Where-Object { $_.SID -eq $rootAccount.SID }
if ($member) {
Remove-LocalGroupMember $group $member -Confirm:$false
Write-Host "The root user was in '$group' and has been removed from it."
}
}
}
# The sshd reads its configuration and finds its helpers in opt/kik; nothing here depends on the user's /usr.
$sshdConfig = "$msys\etc\ssh\sshd_config"
Set-Content -LiteralPath $sshdConfig -Encoding ascii -Value @(
'# The website logs in as root, the deployers as Administrator. Both come in over the websocket bridge.',
'Port 22',
'AllowUsers root Administrator',
'# Only keys may log in: the box is in the open internet and the accounts have passwords.',
'PasswordAuthentication no',
'KbdInteractiveAuthentication no',
'# Files are protected by Windows ACLs; under MSYS2''s noacl mounts the POSIX modes sshd checks are fake.',
'StrictModes no',
'Subsystem sftp internal-sftp',
'# The server and its per-connection helpers are the protected copies, not the ones the user can replace.',
'SshdSessionPath /opt/kik/sshd-session.exe',
'SshdAuthPath /opt/kik/sshd-auth.exe'
)
# The sshd runs as SYSTEM from the protected copy, with opt/kik first on the path so its own DLLs and the session's
# programs (zsh, cat) are the protected ones. The log stays in the install directory, out of the user's reach.
# The log is appended to, not overwritten: it is the only trace of what the server did, and a server that is
# restarted would otherwise take the evidence of the outage with it.
Set-Content -LiteralPath $sshdBat -Encoding ascii -Value @(
'@echo off',
'set PATH=C:\msys2\opt\kik;C:\msys2\usr\bin;%PATH%',
'rem Keep the previous log if it grew too big; the current one is appended to.',
'if exist C:\ProgramData\kik-restore\sshd.log for %%f in (C:\ProgramData\kik-restore\sshd.log) do if %%~zf GEQ 1048576 move /y C:\ProgramData\kik-restore\sshd.log C:\ProgramData\kik-restore\sshd.log.1',
'C:\msys2\opt\kik\sshd.exe -D -e >> C:\ProgramData\kik-restore\sshd.log 2>&1'
)
# The installation's own cygrunsrv sshd service would fight for port 22; the scheduled task owns the sshd instead.
Set-Service $service -StartupType Disabled -ErrorAction SilentlyContinue
Stop-Service $service -Force -ErrorAction SilentlyContinue
$atSystem = New-ScheduledTaskPrincipal -UserId 'SYSTEM' -LogonType ServiceAccount -RunLevel Highest
$sshdAction = New-ScheduledTaskAction -Execute $sshdBat
$sshdSettings = New-ScheduledTaskSettingsSet -MultipleInstances IgnoreNew -ExecutionTimeLimit (New-TimeSpan -Seconds 0) -RestartCount 999 -RestartInterval (New-TimeSpan -Minutes 1) -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries
Register-ScheduledTask -TaskName $sshdTask -Action $sshdAction -Trigger (New-ScheduledTaskTrigger -AtStartup) -Principal $atSystem -Settings $sshdSettings -Force | Out-Null
$restoreAction = New-ScheduledTaskAction -Execute 'powershell.exe' -Argument "-NoProfile -NonInteractive -ExecutionPolicy Bypass -WindowStyle Hidden -File `"$installDir\restore.ps1`" -HomeDir `"$HomeDir`""
$restoreTriggers = @(
New-ScheduledTaskTrigger -Once -At (Get-Date) -RepetitionInterval (New-TimeSpan -Minutes 30) -RepetitionDuration (New-TimeSpan -Days 3650)
New-ScheduledTaskTrigger -AtStartup
)
$restoreSettings = New-ScheduledTaskSettingsSet -StartWhenAvailable -MultipleInstances IgnoreNew -ExecutionTimeLimit (New-TimeSpan -Minutes 10) -RestartCount 3 -RestartInterval (New-TimeSpan -Minutes 5) -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries
Register-ScheduledTask -TaskName $restoreTask -Action $restoreAction -Trigger $restoreTriggers -Principal $atSystem -Settings $restoreSettings -Force | Out-Null
# The server is started and waited for: it must listen on port 22, or the site has no shell.
function Start-Sshd {
Start-ScheduledTask -TaskName $sshdTask
$waited = 0
while (-not (Get-NetTCPConnection -LocalPort 22 -State Listen -ErrorAction SilentlyContinue) -and $waited -lt 30) { Start-Sleep 1; $waited++ }
return [bool](Get-NetTCPConnection -LocalPort 22 -State Listen -ErrorAction SilentlyContinue)
}
# The restore task builds opt/kik and sets every permission; run it before starting the sshd that depends on it.
Start-ScheduledTask -TaskName $restoreTask
Start-Sleep -Seconds 6
$waited = 0
while ((Get-ScheduledTask -TaskName $restoreTask).State -eq 'Running' -and $waited -lt 60) { Start-Sleep 2; $waited += 2 }
# The server is not restarted here. It cannot be: the deployment runs in a session, and the port is still in use by
# that session, so a server that starts now cannot bind it. The cleanup job restarts the server when nobody is
# connected, and the new configuration and the restored programs take effect then. A server that is not running at
# all is started here, because then there is no session that could hold the port.
if (-not (Get-NetTCPConnection -LocalPort 22 -State Listen -ErrorAction SilentlyContinue)) {
if (-not (Start-Sshd)) {
throw "The sshd does not listen on port 22; the task '$sshdTask' says: $((Get-ScheduledTask -TaskName $sshdTask).State), $((Get-ScheduledTaskInfo -TaskName $sshdTask).LastTaskResult)"
}
}
if (-not (Get-NetTCPConnection -LocalPort 22 -State Listen -ErrorAction SilentlyContinue)) {
throw "The sshd does not listen on port 22."
}
Write-Host "The sshd runs as SYSTEM from C:\msys2\opt\kik (task '$sshdTask'); '$restoreTask' keeps it and the home directory in shape."
Get-Content (Join-Path $installDir 'restore.log') -Tail 10 -ErrorAction SilentlyContinue
Get-CimInstance Win32_Process -Filter "Name='sshd.exe'" | ForEach-Object { $_.CommandLine }