CroneKorkN
c6721e7545
Adds the sudo-compatible hardening subset to the web unit. Tightens ProtectSystem=full → strict. NoNewPrivileges, PrivateUsers, RestrictSUIDSGID, empty CapabilityBoundingSet, and ~@privileged in the syscall filter intentionally absent (sudo-incompatible until a future refactor replaces the helper sudo with systemctl-managed transient units). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
391 lines
16 KiB
Python
391 lines
16 KiB
Python
assert node.has_bundle('nftables')
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assert node.has_bundle('systemd')
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assert node.has_bundle('systemd-timers')
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defaults = {
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'left4me': {
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# Application-wide defaults; node only overrides if it really needs to.
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'git_url': 'https://git.sublimity.de/cronekorkn/left4me.git',
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'git_branch': 'master',
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'secret_key': repo.vault.random_bytes_as_base64_for(f'{node.name} left4me secret_key', length=32).value,
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'gunicorn_workers': 1,
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'gunicorn_threads': 32,
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'job_worker_threads': 4,
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# Steam Web API key for the live-state panel's GetPlayerSummaries
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# lookups (persona names + avatars). Empty default — nodes override
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# in their own metadata with the actual key. If left empty in prod,
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# the live-state panel still works but falls back to RCON in-game
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# names and placeholder avatars.
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'steam_web_api_key': '',
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# Whole 27000-block: covers Steam's defaults (27015 game, 27005
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# client/RCON) plus headroom for ad-hoc ports without further
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# nftables changes. Mirrored into LEFT4ME_PORT_RANGE_{START,END}
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# by web.env.mako and into the nftables input rule by the
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# nftables_input reactor below.
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'port_range_start': 27000,
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'port_range_end': 27999,
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},
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'apt': {
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'packages': {
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'p7zip-full': {},
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'nftables': {},
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'iproute2': {},
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'curl': {},
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'ca-certificates': {},
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'python3': {},
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'python3-venv': {},
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'python3-pip': {},
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'python3-dev': {},
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# steamcmd is a 32-bit ELF; needs i386 multiarch + these libs.
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# `_` → `:` is bundlewrap's pkg_apt convention for multiarch
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# names (see pkg_apt.py:48).
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'libc6_i386': { # installs libc6:i386
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'needs': ['action:left4me_dpkg_add_i386_arch'],
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},
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'lib32z1': {
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'needs': ['action:left4me_dpkg_add_i386_arch'],
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},
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},
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},
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'nftables': {
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# Match deploy/files/usr/local/lib/left4me/nft/left4me-mark.nft.
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# Mark srcds UDP egress (uid left4me) with DSCP EF + skb priority 6
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# so CAKE classifies it into the priority tin.
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'output': {
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'meta skuid "left4me" meta l4proto udp ip dscp set ef meta priority set 0006:0000',
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'meta skuid "left4me" meta l4proto udp ip6 dscp set ef meta priority set 0006:0000',
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},
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},
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'systemd': {
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'services': {
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'left4me-web.service': {
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'enabled': True,
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'running': True,
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'needs': [
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'action:left4me_alembic_upgrade',
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'file:/etc/left4me/host.env',
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'file:/etc/left4me/web.env',
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],
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},
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# Note: left4me-server@.service is a TEMPLATE — instances are
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# started on-demand by the web app via the left4me-systemctl
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# helper. Don't enable/start it from here.
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# The slices are installed (file present) but don't need
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# enable/start — they're activated implicitly when a unit
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# uses Slice=.
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},
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},
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'backup': {
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# Application-owned paths. Set-merged with backup group / node-level paths.
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'paths': {
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'/var/lib/left4me',
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'/etc/left4me',
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},
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},
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'systemd-timers': {
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# Daily re-fetch of Steam Workshop metadata + .vpk downloads for any
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# item whose author published an update. The CLI just inserts a
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# `refresh_workshop_items` job; the web worker picks it up next.
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# Idempotent — a re-fire while a refresh is already queued/running
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# is a no-op (see l4d2web/cli.py:workshop_refresh).
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'left4me-workshop-refresh': {
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'command': '/opt/left4me/.venv/bin/flask --app l4d2web.app:create_app workshop-refresh',
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'when': '*-*-* 04:00:00',
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'persistent': True,
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'user': 'left4me',
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'working_dir': '/opt/left4me/src',
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'environment_files': (
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'/etc/left4me/host.env',
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'/etc/left4me/web.env',
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),
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'after': {
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'network-online.target',
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'left4me-web.service',
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},
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},
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},
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}
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# Hardening composition — proven via the hardening test plan (left4me
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# commit 461b8d0). See:
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# docs/superpowers/specs/2026-05-15-hardening-threat-model.md
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# docs/superpowers/specs/2026-05-15-hardening-defenses-survey.md
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# docs/superpowers/specs/2026-05-15-hardening-test-plan.md
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# docs/superpowers/specs/2026-05-15-hardening-refactor-design.md
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# (paths in the left4me repo)
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# Directives both managed units take verbatim.
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HARDENING_COMMON = {
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'ProtectProc': 'invisible',
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'ProcSubset': 'pid',
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'ProtectKernelTunables': 'true',
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'ProtectKernelModules': 'true',
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'ProtectKernelLogs': 'true',
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'ProtectClock': 'true',
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'ProtectControlGroups': 'true',
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'ProtectHostname': 'true',
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'LockPersonality': 'true',
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'ProtectSystem': 'strict',
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'ProtectHome': 'true',
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'PrivateTmp': 'true',
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'RestrictNamespaces': 'true',
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'RestrictRealtime': 'true',
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'RemoveIPC': 'true',
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'KeyringMode': 'private',
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'UMask': '0027',
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'RestrictAddressFamilies': 'AF_INET AF_INET6 AF_UNIX',
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}
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# Gameserver unit: COMMON + sudo-incompatible flags + filesystem
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# virtualization + i386 amendment + per-instance PID namespace + bound
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# socket binds.
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HARDENING_SERVER = {
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**HARDENING_COMMON,
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'NoNewPrivileges': 'true',
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'RestrictSUIDSGID': 'true',
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'PrivateUsers': 'true',
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# PrivatePIDs is the test-plan amendment that closes D2.b: same-uid
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# ProtectProc=invisible cannot hide gunicorn from srcds (both run
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# as uid 980); a private PID namespace does.
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'PrivatePIDs': 'true',
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'PrivateIPC': 'true',
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'PrivateDevices': 'true',
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'CapabilityBoundingSet': '',
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'AmbientCapabilities': '',
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# srcds_linux is i386 (Source 2007 engine). Bare 'native' kills
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# every 32-bit syscall and traps srcds_run in a respawn loop.
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'SystemCallArchitectures': 'native x86',
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'SystemCallFilter': (
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'@system-service',
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'~@debug @mount @raw-io @reboot @swap @cpu-emulation @obsolete @privileged',
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),
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'TemporaryFileSystem': '/var/lib /etc /opt /home /root /srv /mnt /media',
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'BindReadOnlyPaths': (
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'/var/lib/left4me/installation',
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'/var/lib/left4me/overlays',
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'/etc/left4me/host.env',
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'/etc/ssl',
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'/etc/ca-certificates',
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'/etc/resolv.conf',
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'/etc/nsswitch.conf',
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'/etc/alternatives',
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),
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'BindPaths': '/var/lib/left4me/runtime/%i',
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# Lock srcds bindable sockets to the game port range. Hard-coded
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# range because systemd directive variable substitution is uneven.
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'SocketBindAllow': (
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'udp:27000-27999',
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'tcp:27000-27999',
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),
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# MemoryDenyWriteExecute=true permanently excluded — Source engine
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# i386 .so files have text relocations that need mprotect(W+X)
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# during the dynamic linker's relocation pass.
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}
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# Web unit: COMMON + sudo-compatible additions. EXCLUDES
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# NoNewPrivileges, PrivateUsers, RestrictSUIDSGID, empty
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# CapabilityBoundingSet, and ~@privileged in the syscall filter — all
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# sudo-incompatible until a future refactor replaces sudo with
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# systemctl-managed transient units.
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HARDENING_WEB = {
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**HARDENING_COMMON,
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'SystemCallArchitectures': 'native',
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'SystemCallFilter': (
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'@system-service',
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'~@debug @mount @raw-io @reboot @swap @cpu-emulation @obsolete',
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),
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}
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@metadata_reactor.provides(
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'nginx/vhosts',
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)
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def nginx_vhosts(metadata):
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# letsencrypt/domains and monitoring/services for the vhost are auto-
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# populated by bundles/nginx/metadata.py. We just declare check_path:
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# '/health' so the auto-check hits the Flask health endpoint, not '/'.
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domain = metadata.get('left4me/domain')
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return {
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'nginx': {
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'vhosts': {
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domain: {
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'content': 'nginx/proxy_pass.conf',
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'context': {
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'target': 'http://127.0.0.1:8000',
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},
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'check_path': '/health',
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},
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},
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},
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}
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@metadata_reactor.provides(
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'nftables/input',
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)
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def nftables_input(metadata):
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port_start = metadata.get('left4me/port_range_start')
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port_end = metadata.get('left4me/port_range_end')
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return {
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'nftables': {
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'input': {
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f'udp dport {port_start}-{port_end} accept',
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f'tcp dport {port_start}-{port_end} accept',
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},
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},
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}
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@metadata_reactor.provides(
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'systemd/units',
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)
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def systemd_units(metadata):
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workers = metadata.get('left4me/gunicorn_workers')
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threads = metadata.get('left4me/gunicorn_threads')
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# cgroup-v2 cpuset. `system_cpus` (set of int CPU ids, declared per
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# node) pins system/user/build; the complement pins l4d2-game. On HT
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# hosts, list both siblings of a physical core so games don't share
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# L1/L2 with system work — pairings via
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# /sys/devices/system/cpu/cpu<n>/topology/thread_siblings_list.
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vm_threads = metadata.get('vm/threads', metadata.get('vm/cores'))
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all_cpus = set(range(vm_threads))
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system_cpus = metadata.get('left4me/system_cpus')
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if not system_cpus <= all_cpus:
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raise Exception(
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f'left4me/system_cpus={sorted(system_cpus)} on {vm_threads}-thread host '
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f'includes CPUs outside [0, {vm_threads})'
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)
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game_cpus = all_cpus - system_cpus
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if not game_cpus:
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raise Exception(
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f'left4me/system_cpus={sorted(system_cpus)} on {vm_threads}-thread host '
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f'leaves no cores for games'
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)
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system_cpus_string = ','.join(str(t) for t in sorted(system_cpus))
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game_cpus_string = ','.join(str(t) for t in sorted(game_cpus))
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# Drop-in for upstream system.slice / user.slice (units we don't own).
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# Same '<parent>.d/<basename>.conf' convention as nginx and autologin.
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cpuset_dropin = {'Slice': {'AllowedCPUs': system_cpus_string}}
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return {
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'systemd': {
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'units': {
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'left4me-web.service': {
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'Unit': {
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'Description': 'left4me web application',
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'After': 'network-online.target',
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'Wants': 'network-online.target',
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},
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'Service': {
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'Type': 'simple',
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'User': 'left4me',
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'Group': 'left4me',
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'WorkingDirectory': '/opt/left4me/src',
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'Environment': {
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'HOME=/var/lib/left4me',
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'PATH=/opt/left4me/.venv/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin',
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},
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'EnvironmentFile': (
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'/etc/left4me/host.env',
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'/etc/left4me/web.env',
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),
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'ExecStart': (
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'/opt/left4me/.venv/bin/gunicorn '
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f'--workers {workers} --threads {threads} '
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"--bind 127.0.0.1:8000 'l4d2web.app:create_app()'"
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),
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'Restart': 'on-failure',
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'RestartSec': '3',
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# Web app writes broadly under /var/lib/left4me. Kept inline
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# because it's web-specific (server@ uses BindPaths to bind
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# only its instance dir).
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'ReadWritePaths': '/var/lib/left4me',
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# Hardening profile — see HARDENING_WEB constant near top of
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# this file. NoNewPrivileges intentionally NOT set: workers
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# sudo to the helpers. PrivateUsers and RestrictSUIDSGID also
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# absent for the same reason. ProtectSystem tightens from
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# 'full' to 'strict' via HARDENING_COMMON.
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**HARDENING_WEB,
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},
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'Install': {
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'WantedBy': {'multi-user.target'},
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},
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},
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'left4me-server@.service': {
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'Unit': {
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'Description': 'left4me server instance %i',
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'After': 'network-online.target',
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'Wants': 'network-online.target',
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'StartLimitBurst': '5',
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'StartLimitIntervalSec': '60s',
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},
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'Service': {
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'Type': 'simple',
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'User': 'left4me',
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'Group': 'left4me',
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'EnvironmentFile': (
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'/etc/left4me/host.env',
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'/var/lib/left4me/instances/%i/instance.env',
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),
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'WorkingDirectory': '-/var/lib/left4me/runtime/%i/merged/left4dead2',
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'ExecStartPre': '+/usr/bin/nsenter --mount=/proc/1/ns/mnt -- /usr/local/libexec/left4me/left4me-overlay mount %i',
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'ExecStart': '/var/lib/left4me/runtime/%i/merged/srcds_run -game left4dead2 +hostport ${L4D2_PORT} $L4D2_ARGS',
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'ExecStopPost': '+/usr/bin/nsenter --mount=/proc/1/ns/mnt -- /usr/local/libexec/left4me/left4me-overlay umount %i',
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'Restart': 'on-failure',
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'RestartSec': '5',
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# Resource control (baseline from prior performance work).
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'Slice': 'l4d2-game.slice',
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'Nice': '-5',
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'IOSchedulingClass': 'best-effort',
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'IOSchedulingPriority': '4',
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'OOMScoreAdjust': '-200',
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'MemoryHigh': '1.5G',
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'MemoryMax': '2G',
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'TasksMax': '256',
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'LimitNOFILE': '65536',
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'KillSignal': 'SIGINT',
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'TimeoutStopSec': '15s',
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'LogRateLimitIntervalSec': '0',
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# Hardening profile — see HARDENING_SERVER constant near top of
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# this file for per-directive rationale.
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**HARDENING_SERVER,
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},
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'Install': {
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'WantedBy': {'multi-user.target'},
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},
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},
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'l4d2-game.slice': {
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'Unit': {
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'Description': 'left4me game-server slice',
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'Before': 'slices.target',
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},
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'Slice': {
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'CPUWeight': '1000',
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'IOWeight': '1000',
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'AllowedCPUs': game_cpus_string,
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},
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},
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'l4d2-build.slice': {
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'Unit': {
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'Description': 'left4me script-sandbox build slice',
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'Before': 'slices.target',
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},
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'Slice': {
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'CPUWeight': '10',
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'IOWeight': '10',
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'AllowedCPUs': system_cpus_string,
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},
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},
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'system.slice.d/99-left4me-cpuset.conf': cpuset_dropin,
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'user.slice.d/99-left4me-cpuset.conf': cpuset_dropin,
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},
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},
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}
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