mirror of
https://github.com/kuhyx/steam-backlog-enforcer.git
synced 2026-11-10 19:27:04 +01:00
Krzysztof kuhy Rudnicki
21fe2f7742
The enforce service runs as root (no User=) but sets DISPLAY=:0, so any GUI
it starts lands on the desktop session. Two resolvers disagreed about who to
drop privileges to:
library_hider._resolve_desktop_user() read STEAM_ENFORCER_DESKTOP_USER
game_install._get_real_user() read only SUDO_USER or USER
systemd sets neither of the latter, so _get_real_user() returned None under
the service and every `geteuid() == 0 and real_user and ...` guard fell
through to running as root. Steam answered with a zenity modal ("Cannot run
as root user", /usr/lib/steam/steam:261) on screen.
Confirmed from the live process tree: root `bash /usr/lib/steam/steam
-cef-disable-gpu ... steam://install/618510` with a root zenity child. It
never reached the journal, because that text goes to zenity and _run_as_user
sends child output to DEVNULL.
- _desktop_env: add resolve_desktop_user/desktop_uid/desktop_user_cmd. Only
the argv builder is shared, never the spawn call: tests/_no_subprocess.py
patches subprocess per module by name, so a spawn site in an unpatched
module could fire a real `sudo -u kuhy steam`.
- game_install._get_real_user: delegate to the shared resolver. This alone
also fixes the root `steam -silent` in _ensure_steam_running and the
no-op os.chown on new appmanifests.
- _trigger_steam_install / enforcer.send_notification: drop privileges.
send_notification had no DBUS_SESSION_BUS_ADDRESS, so it silently reached
nobody for all six of its callers.
- _run_as_user: fail closed. Running unchanged as root when no desktop user
resolves is what put the modal on screen; refuse and log instead.
Also stop the retry storm behind it. steamapps does not exist (Steam has
never completed sign-in), so is_game_installed() was always False and the
loop re-triggered every allowed game every pass: 1656 attempts in 30
minutes, service RSS 1.5 GB (peak 4.3 GB), a FileNotFoundError traceback
each time. Guard install_game and _reinstall_missing_allowed on
steam_library_ready() -- a missing library means no install can succeed by
any route, so this is a correctness check rather than a tuned retry limit.
The module splits here are forced by the pre-commit 250-line gate, which
blocks any commit touching an over-cap file: game_install, library_hider and
_enforce_loop were already over before this change. They are split by
responsibility (_cdp transport, _steam_launch lifecycle, _steam_process
spawning, _steam_errors, _steam_client, _game_names, game_uninstall,
_enforce_steps, _owned_apps_cache, _echo, _protected_apps). game_install and
library_hider re-export their old public names, so the 15 modules that
import from them are untouched by this commit.
Verified as real root under the unit's environment: argv is now
`sudo -u kuhy env DISPLAY=:0 ... xdg-open steam://install/...` for both the
installer and notify-send; three enforce passes spawn no process and log
once; _run_as_user refuses with no desktop user. After restart: 0 retries,
0 tracebacks, 0 root-owned files under ~/.local/share/Steam, RSS 342 MB.
1311 tests pass. _desktop_env and _steam_state at 100% branch coverage.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016A1EYiv7e7HGhET84oa9M3
59 lines
2.0 KiB
Python
59 lines
2.0 KiB
Python
"""Spawning processes as the desktop user, and reaping them.
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Split out of :mod:`steam_backlog_enforcer._steam_launch` to keep both under
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the 250-line cap. Owns the fire-and-forget process registry so it has a single
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owner rather than a global shared across responsibilities.
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"""
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from __future__ import annotations
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import logging
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import os
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import subprocess
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from steam_backlog_enforcer._desktop_env import desktop_user_cmd
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logger = logging.getLogger(__name__)
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# Handles for fire-and-forget launches, kept only so they can be reaped.
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_SPAWNED: list[subprocess.Popen[bytes]] = []
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def _reap_spawned() -> None:
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"""Clear out previously launched processes that have since exited.
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Launches here are fire-and-forget: Steam is meant to outlive the call, so
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it is never waited on. That leaves any launch which dies immediately - a
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missing binary, a broken wrapper - sitting as a zombie that still carries
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the name ``steam``, which anything scanning /proc reads as "Steam is
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running". Polling the old handles reaps them and retires the name.
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"""
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_SPAWNED[:] = [proc for proc in _SPAWNED if proc.poll() is None]
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def _run_as_user(cmd: list[str], user: str | None) -> None:
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"""Run a command, dropping to *user* if currently root.
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Refuses to run at all when root and no desktop user resolves: the command
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would otherwise execute *as root* on the user's session, which is how the
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enforcer put a root Steam ("Cannot run as root user") on screen.
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Failing closed costs one skipped pass; failing open costs a modal.
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"""
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_reap_spawned()
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if os.geteuid() == 0 and (not user or user == "root"):
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logger.error(
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"Refusing to run %s as root: no desktop user resolved "
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"(is STEAM_ENFORCER_DESKTOP_USER set?)",
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cmd[0] if cmd else "<empty>",
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)
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return
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full_cmd = desktop_user_cmd(cmd, user)
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_SPAWNED.append(
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subprocess.Popen(
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full_cmd,
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stdout=subprocess.DEVNULL,
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stderr=subprocess.DEVNULL,
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)
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)
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