hermes-agent/tests/tools/test_browser_orphan_reaper.py
teknium1 624580e836 fix(browser): verify daemon identity before orphan reaper kills a PID (#14073)
The browser orphan reaper reads a daemon PID from a `.pid` file in a
world-writable, predictably-named temp dir (`/tmp/agent-browser-h_*`) it
does not write itself, then tree-kills that PID via `_terminate_host_pid`
after only a liveness check. A same-user actor could plant a fake socket
dir whose `.pid` points at an arbitrary victim process, and OS PID reuse
after the real daemon exits could land the recorded PID on an unrelated
process — either way an arbitrary same-user process (and its whole tree)
gets SIGTERMed. Local DoS.

Add `_verify_reapable_browser_daemon()`, gated before the kill: via psutil
(a hard dep, fine cross-platform for the same-user processes the reaper can
signal) require both (1) identity — `agent-browser` in the process
name/cmdline — and (2) binding — the live process references *this* session's
socket dir in its cmdline or `AGENT_BROWSER_SOCKET_DIR`. The binding check is
the real spoof defense: a planted/recycled PID won't embed our exact socket
path. Fail-closed on any ambiguity (unreadable cmdline, no match), leaving the
process and its socket dir untouched for a later sweep.

Builds on @sgaofen's fix in #14394 (cmdline identity check); rewritten to use
psutil instead of `/proc`+`ps` (cross-platform, Windows-covered) and to add
the session-socket-dir binding check for recycled-PID / spoof resistance.

Co-authored-by: sgaofen <135070653+sgaofen@users.noreply.github.com>
2026-06-21 15:23:47 -07:00

539 lines
21 KiB
Python

"""Tests for _reap_orphaned_browser_sessions() — kills orphaned agent-browser
daemons whose Python parent exited without cleaning up."""
import os
from unittest.mock import patch
import pytest
@pytest.fixture
def fake_tmpdir(tmp_path):
"""Patch _socket_safe_tmpdir to return a temp dir we control."""
with patch("tools.browser_tool._socket_safe_tmpdir", return_value=str(tmp_path)):
yield tmp_path
@pytest.fixture(autouse=True)
def _isolate_sessions():
"""Ensure _active_sessions is empty for each test."""
import tools.browser_tool as bt
orig = bt._active_sessions.copy()
bt._active_sessions.clear()
yield
bt._active_sessions.clear()
bt._active_sessions.update(orig)
def _make_socket_dir(tmpdir, session_name, pid=None, owner_pid=None):
"""Create a fake agent-browser socket directory with optional PID files.
Args:
tmpdir: base temp directory
session_name: name like "h_abc1234567" or "cdp_abc1234567"
pid: daemon PID to write to <session>.pid (None = no file)
owner_pid: owning hermes PID to write to <session>.owner_pid
(None = no file; tests the legacy path)
"""
d = tmpdir / f"agent-browser-{session_name}"
d.mkdir()
if pid is not None:
(d / f"{session_name}.pid").write_text(str(pid))
if owner_pid is not None:
(d / f"{session_name}.owner_pid").write_text(str(owner_pid))
return d
class TestReapOrphanedBrowserSessions:
"""Tests for the orphan reaper function."""
def test_no_socket_dirs_is_noop(self, fake_tmpdir):
"""No socket dirs => nothing happens, no errors."""
from tools.browser_tool import _reap_orphaned_browser_sessions
_reap_orphaned_browser_sessions() # should not raise
def test_stale_dir_without_pid_file_is_removed(self, fake_tmpdir):
"""Socket dir with no PID file is cleaned up."""
from tools.browser_tool import _reap_orphaned_browser_sessions
d = _make_socket_dir(fake_tmpdir, "h_abc1234567")
assert d.exists()
_reap_orphaned_browser_sessions()
assert not d.exists()
def test_stale_dir_with_dead_pid_is_removed(self, fake_tmpdir):
"""Socket dir whose daemon PID is dead gets cleaned up."""
from tools.browser_tool import _reap_orphaned_browser_sessions
d = _make_socket_dir(fake_tmpdir, "h_dead123456", pid=999999999)
assert d.exists()
_reap_orphaned_browser_sessions()
assert not d.exists()
def test_orphaned_alive_daemon_is_killed(self, fake_tmpdir):
"""Alive daemon not tracked by _active_sessions is terminated (legacy path).
No owner_pid file => falls back to tracked_names check.
"""
from tools.browser_tool import _reap_orphaned_browser_sessions
d = _make_socket_dir(fake_tmpdir, "h_orphan12345", pid=12345)
kill_calls = []
def mock_terminate(pid):
kill_calls.append(pid)
# Post-#21561 the liveness probe goes through
# ``gateway.status._pid_exists`` (which wraps ``psutil.pid_exists``
# so it's safe on Windows — ``os.kill(pid, 0)`` is bpo-14484).
# The identity guard (#14073) is mocked True here — its own behavior
# is covered by TestReaperIdentityGuard below.
with patch("gateway.status._pid_exists", return_value=True), \
patch("tools.browser_tool._verify_reapable_browser_daemon", return_value=True), \
patch("tools.process_registry.ProcessRegistry._terminate_host_pid", side_effect=mock_terminate):
_reap_orphaned_browser_sessions()
assert 12345 in kill_calls
def test_tracked_session_is_not_reaped(self, fake_tmpdir):
"""Sessions tracked in _active_sessions are left alone (legacy path)."""
import tools.browser_tool as bt
from tools.browser_tool import _reap_orphaned_browser_sessions
session_name = "h_tracked1234"
d = _make_socket_dir(fake_tmpdir, session_name, pid=12345)
# Register the session as actively tracked
bt._active_sessions["some_task"] = {"session_name": session_name}
kill_calls = []
def mock_terminate(pid):
kill_calls.append(pid)
with patch("tools.process_registry.ProcessRegistry._terminate_host_pid", side_effect=mock_terminate):
_reap_orphaned_browser_sessions()
# Should NOT have tried to terminate anything
assert len(kill_calls) == 0
# Dir should still exist
assert d.exists()
def test_alive_legacy_daemon_is_reaped(self, fake_tmpdir):
"""Alive, untracked, legacy (no owner_pid) daemon is reaped.
Post-#21561 the liveness probe goes through
``gateway.status._pid_exists`` (which wraps ``psutil.pid_exists``
because ``os.kill(pid, 0)`` is a footgun on Windows — bpo-14484).
With no owner_pid file and no tracked-name entry, the reaper
terminates the daemon (and its process tree) and removes its socket
dir regardless of whether termination succeeded (best-effort
semantics).
"""
from tools.browser_tool import _reap_orphaned_browser_sessions
d = _make_socket_dir(fake_tmpdir, "h_perm1234567", pid=12345)
terminate_calls = []
def mock_terminate(pid):
terminate_calls.append(pid)
with patch("gateway.status._pid_exists", return_value=True), \
patch("tools.browser_tool._verify_reapable_browser_daemon", return_value=True), \
patch("tools.process_registry.ProcessRegistry._terminate_host_pid", side_effect=mock_terminate):
_reap_orphaned_browser_sessions()
assert 12345 in terminate_calls
assert not d.exists()
def test_cdp_sessions_are_also_reaped(self, fake_tmpdir):
"""CDP sessions (cdp_ prefix) are also scanned."""
from tools.browser_tool import _reap_orphaned_browser_sessions
d = _make_socket_dir(fake_tmpdir, "cdp_abc1234567")
assert d.exists()
_reap_orphaned_browser_sessions()
# No PID file → cleaned up
assert not d.exists()
def test_non_hermes_dirs_are_ignored(self, fake_tmpdir):
"""Socket dirs that don't match our naming pattern are left alone."""
from tools.browser_tool import _reap_orphaned_browser_sessions
# Create a dir that doesn't match h_* or cdp_* pattern
d = fake_tmpdir / "agent-browser-other_session"
d.mkdir()
(d / "other_session.pid").write_text("12345")
_reap_orphaned_browser_sessions()
# Should NOT be touched
assert d.exists()
def test_corrupt_pid_file_is_cleaned(self, fake_tmpdir):
"""PID file with non-integer content is cleaned up."""
from tools.browser_tool import _reap_orphaned_browser_sessions
d = _make_socket_dir(fake_tmpdir, "h_corrupt1234")
(d / "h_corrupt1234.pid").write_text("not-a-number")
_reap_orphaned_browser_sessions()
assert not d.exists()
class TestOwnerPidCrossProcess:
"""Tests for owner_pid-based cross-process safe reaping.
The owner_pid file records which hermes process owns a daemon so that
concurrent hermes processes don't reap each other's active browser
sessions. Added to fix orphan accumulation from crashed processes.
"""
def test_alive_owner_is_not_reaped_even_when_untracked(self, fake_tmpdir):
"""Daemon with alive owner_pid is NOT reaped, even if not in our _active_sessions.
This is the core cross-process safety check: Process B scanning while
Process A is using a browser must not kill A's daemon.
"""
from tools.browser_tool import _reap_orphaned_browser_sessions
# Use our own PID as the "owner" — guaranteed alive
d = _make_socket_dir(
fake_tmpdir, "h_alive_owner", pid=12345, owner_pid=os.getpid()
)
kill_calls = []
def mock_terminate(pid):
kill_calls.append(pid)
# Owner alive → reaper skips without ever probing the daemon.
with patch("gateway.status._pid_exists", return_value=True), \
patch("tools.process_registry.ProcessRegistry._terminate_host_pid", side_effect=mock_terminate):
_reap_orphaned_browser_sessions()
assert 12345 not in kill_calls
assert d.exists()
def test_dead_owner_triggers_reap(self, fake_tmpdir):
"""Daemon whose owner_pid is dead gets reaped."""
from tools.browser_tool import _reap_orphaned_browser_sessions
# PID 999999999 almost certainly doesn't exist
d = _make_socket_dir(
fake_tmpdir, "h_dead_owner1", pid=12345, owner_pid=999999999
)
kill_calls = []
def mock_terminate(pid):
kill_calls.append(pid)
# Owner 999999999 dead, daemon 12345 alive.
pid_alive = {999999999: False, 12345: True}
with patch("gateway.status._pid_exists",
side_effect=lambda pid: pid_alive.get(int(pid), False)), \
patch("tools.browser_tool._verify_reapable_browser_daemon", return_value=True), \
patch("tools.process_registry.ProcessRegistry._terminate_host_pid", side_effect=mock_terminate):
_reap_orphaned_browser_sessions()
assert 12345 in kill_calls
assert not d.exists()
def test_corrupt_owner_pid_falls_back_to_legacy(self, fake_tmpdir):
"""Corrupt owner_pid file → fall back to tracked_names check."""
import tools.browser_tool as bt
from tools.browser_tool import _reap_orphaned_browser_sessions
session_name = "h_corrupt_own"
d = _make_socket_dir(fake_tmpdir, session_name, pid=12345)
# Write garbage to owner_pid file
(d / f"{session_name}.owner_pid").write_text("not-a-pid")
# Register session so legacy fallback leaves it alone
bt._active_sessions["task"] = {"session_name": session_name}
kill_calls = []
def mock_terminate(pid):
kill_calls.append(pid)
with patch("gateway.status._pid_exists", return_value=True), \
patch("tools.process_registry.ProcessRegistry._terminate_host_pid", side_effect=mock_terminate):
_reap_orphaned_browser_sessions()
# Legacy path took over → tracked → not reaped
assert 12345 not in kill_calls
assert d.exists()
def test_owner_pid_permission_error_treated_as_alive(self, fake_tmpdir):
"""Owner PID owned by another user → treat as alive.
Post-#21561 this is handled inside ``gateway.status._pid_exists``
(via psutil's ``OpenProcess`` returning ``ERROR_ACCESS_DENIED`` on
Windows, or via the POSIX fallback's ``except PermissionError``
branch). Exposed to callers as ``alive=True``.
"""
from tools.browser_tool import _reap_orphaned_browser_sessions
d = _make_socket_dir(
fake_tmpdir, "h_perm_owner1", pid=12345, owner_pid=22222
)
kill_calls = []
def mock_terminate(pid):
kill_calls.append(pid)
# Owner 22222 reported alive (PermissionError collapses to True
# inside _pid_exists). Daemon never probed, never terminated.
with patch("gateway.status._pid_exists", return_value=True), \
patch("tools.process_registry.ProcessRegistry._terminate_host_pid", side_effect=mock_terminate):
_reap_orphaned_browser_sessions()
assert 12345 not in kill_calls
assert d.exists()
def test_write_owner_pid_creates_file_with_current_pid(
self, fake_tmpdir, monkeypatch
):
"""_write_owner_pid(dir, session) writes <session>.owner_pid with os.getpid()."""
import tools.browser_tool as bt
session_name = "h_ownertest01"
socket_dir = fake_tmpdir / f"agent-browser-{session_name}"
socket_dir.mkdir()
bt._write_owner_pid(str(socket_dir), session_name)
owner_pid_file = socket_dir / f"{session_name}.owner_pid"
assert owner_pid_file.exists()
assert owner_pid_file.read_text().strip() == str(os.getpid())
def test_write_owner_pid_is_idempotent(self, fake_tmpdir):
"""Calling _write_owner_pid twice leaves a single owner_pid file."""
import tools.browser_tool as bt
session_name = "h_idempot1234"
socket_dir = fake_tmpdir / f"agent-browser-{session_name}"
socket_dir.mkdir()
bt._write_owner_pid(str(socket_dir), session_name)
bt._write_owner_pid(str(socket_dir), session_name)
files = list(socket_dir.glob("*.owner_pid"))
assert len(files) == 1
assert files[0].read_text().strip() == str(os.getpid())
def test_write_owner_pid_swallows_oserror(self, fake_tmpdir, monkeypatch):
"""OSError (e.g. permission denied) doesn't propagate — the reaper
falls back to the legacy tracked_names heuristic in that case.
"""
import tools.browser_tool as bt
def raise_oserror(*a, **kw):
raise OSError("permission denied")
monkeypatch.setattr("builtins.open", raise_oserror)
# Must not raise
bt._write_owner_pid(str(fake_tmpdir), "h_readonly123")
def test_run_browser_command_calls_write_owner_pid(
self, fake_tmpdir, monkeypatch
):
"""_run_browser_command wires _write_owner_pid after mkdir."""
import tools.browser_tool as bt
session_name = "h_wiringtest1"
# Short-circuit Popen so we exit after the owner_pid write
class _FakePopen:
def __init__(self, *a, **kw):
raise RuntimeError("short-circuit after owner_pid")
monkeypatch.setattr(bt.subprocess, "Popen", _FakePopen)
monkeypatch.setattr(bt, "_find_agent_browser", lambda: "/bin/true")
monkeypatch.setattr(
bt, "_requires_real_termux_browser_install", lambda *a: False
)
monkeypatch.setattr(bt, "_chromium_installed", lambda: True)
monkeypatch.setattr(
bt, "_get_session_info",
lambda task_id: {"session_name": session_name},
)
calls = []
orig_write = bt._write_owner_pid
def _spy(*a, **kw):
calls.append(a)
orig_write(*a, **kw)
monkeypatch.setattr(bt, "_write_owner_pid", _spy)
with patch("tools.browser_tool._socket_safe_tmpdir", return_value=str(fake_tmpdir)):
try:
bt._run_browser_command(task_id="test_task", command="goto", args=[])
except Exception:
pass
assert calls, "_run_browser_command must call _write_owner_pid"
# First positional arg is the socket_dir, second is the session_name
socket_dir_arg, session_name_arg = calls[0][0], calls[0][1]
assert session_name_arg == session_name
assert session_name in socket_dir_arg
class TestReaperIdentityGuard:
"""Tests for _verify_reapable_browser_daemon — the #14073 fix.
The reaper reads daemon PIDs from world-writable, predictably-named temp
dirs. Before tree-killing a live PID it must confirm the process really is
*this* session's agent-browser daemon, defeating planted pid files and
recycled PIDs that would otherwise become an arbitrary same-user DoS.
"""
class _FakeProc:
def __init__(self, name="agent-browser", cmdline=None, environ=None,
raise_environ=False):
self._name = name
self._cmdline = cmdline if cmdline is not None else []
self._environ = environ or {}
self._raise_environ = raise_environ
def name(self):
return self._name
def cmdline(self):
return self._cmdline
def environ(self):
if self._raise_environ:
import psutil
raise psutil.AccessDenied()
return self._environ
def _run(self, fake_proc, socket_dir, session_name="h_sess123456",
daemon_pid=12345, no_such=False, access_denied=False):
import psutil
from tools.browser_tool import _verify_reapable_browser_daemon
def _factory(pid):
if no_such:
raise psutil.NoSuchProcess(pid)
if access_denied:
raise psutil.AccessDenied(pid)
return fake_proc
with patch("psutil.Process", side_effect=_factory):
return _verify_reapable_browser_daemon(
daemon_pid, socket_dir, session_name)
def test_real_daemon_bound_via_cmdline_is_reapable(self):
socket_dir = "/tmp/agent-browser-h_sess123456"
proc = self._FakeProc(
name="agent-browser",
cmdline=["agent-browser", "open", "--session", "h_sess123456",
"--socket-dir", socket_dir],
)
assert self._run(proc, socket_dir) is True
def test_daemon_bound_via_environ_is_reapable(self):
socket_dir = "/tmp/agent-browser-h_sess123456"
proc = self._FakeProc(
name="agent-browser-linux-x64",
cmdline=["agent-browser-linux-x64", "daemon"], # no dir in cmd
environ={"AGENT_BROWSER_SOCKET_DIR": socket_dir},
)
assert self._run(proc, socket_dir) is True
def test_planted_pid_for_non_browser_process_is_refused(self):
"""A planted .pid pointing at e.g. `sleep 600` must NOT be reaped."""
socket_dir = "/tmp/agent-browser-h_sess123456"
proc = self._FakeProc(name="sleep", cmdline=["/bin/sleep", "600"])
assert self._run(proc, socket_dir) is False
def test_recycled_pid_browser_not_bound_to_our_dir_is_refused(self):
"""An agent-browser process for a DIFFERENT session must not be reaped.
Models PID reuse / a concurrent unrelated daemon: it looks like
agent-browser but is bound to another socket dir.
"""
socket_dir = "/tmp/agent-browser-h_sess123456"
proc = self._FakeProc(
name="agent-browser",
cmdline=["agent-browser", "open", "--session", "h_OTHER999",
"--socket-dir", "/tmp/agent-browser-h_OTHER999"],
environ={"AGENT_BROWSER_SOCKET_DIR":
"/tmp/agent-browser-h_OTHER999"},
)
assert self._run(proc, socket_dir) is False
def test_browser_name_but_environ_denied_and_no_cmdline_bind_refused(self):
"""Looks like browser, cmdline doesn't bind, environ() denied -> refuse."""
socket_dir = "/tmp/agent-browser-h_sess123456"
proc = self._FakeProc(
name="agent-browser",
cmdline=["agent-browser", "daemon"], # no dir
raise_environ=True,
)
assert self._run(proc, socket_dir) is False
def test_vanished_process_is_not_reapable(self):
socket_dir = "/tmp/agent-browser-h_sess123456"
assert self._run(None, socket_dir, no_such=True) is False
def test_access_denied_on_identity_read_refuses(self):
socket_dir = "/tmp/agent-browser-h_sess123456"
assert self._run(None, socket_dir, access_denied=True) is False
def test_planted_pid_survives_full_reaper_path(self, fake_tmpdir):
"""End-to-end through the reaper: a planted non-browser PID is spared.
No owner_pid (legacy path), not tracked, PID 'alive' — but the live
process is `sleep`, not agent-browser, so it must be left alone and the
socket dir retained.
"""
from tools.browser_tool import _reap_orphaned_browser_sessions
d = _make_socket_dir(fake_tmpdir, "h_planted9999", pid=12345)
terminate_calls = []
proc = self._FakeProc(name="sleep", cmdline=["/bin/sleep", "600"])
with patch("gateway.status._pid_exists", return_value=True), \
patch("psutil.Process", return_value=proc), \
patch("tools.process_registry.ProcessRegistry._terminate_host_pid",
side_effect=lambda pid: terminate_calls.append(pid)):
_reap_orphaned_browser_sessions()
assert terminate_calls == [], "planted non-browser PID must not be killed"
assert d.exists(), "socket dir retained for a later sweep"
class TestEmergencyCleanupRunsReaper:
"""Verify atexit-registered cleanup sweeps orphans even without an active session."""
def test_emergency_cleanup_calls_reaper(self, fake_tmpdir, monkeypatch):
"""_emergency_cleanup_all_sessions must call _reap_orphaned_browser_sessions."""
import tools.browser_tool as bt
# Reset the _cleanup_done flag so the cleanup actually runs
monkeypatch.setattr(bt, "_cleanup_done", False)
reaper_called = []
orig_reaper = bt._reap_orphaned_browser_sessions
def _spy_reaper():
reaper_called.append(True)
orig_reaper()
monkeypatch.setattr(bt, "_reap_orphaned_browser_sessions", _spy_reaper)
# No active sessions — reaper should still run
bt._emergency_cleanup_all_sessions()
assert reaper_called, (
"Reaper must run on exit even with no active sessions"
)