fix: always terminate host component when browser is terminated

On chrome and chromium, the native part is not reliably terminated when
the browser is terminated. As we also cannot reliably send a message to
the host part on termination of the browser, there is no direct way to
let the host script known. In theory, the script should terminate once
stdio is closed, but in practice this is not always the case, leading to
orphaned processes.

To fix this, we use prctl to register a PDEATHSIG handler.

Signed-off-by: Felix Moessbauer <[email protected]>

linux-entra-sso.py

@@ -12,6 +12,8 @@
 import json
 import struct
 import uuid
+import ctypes
+from signal import SIGINT
 from threading import Thread, Lock
 from gi.repository import GLib
 from pydbus import SessionBus
@@ -25,6 +27,8 @@
 # dbus start service reply codes
 START_REPLY_SUCCESS = 1
 START_REPLY_ALREADY_RUNNING = 2
+# prctl constants
+PR_SET_PDEATHSIG = 1
 
 
 class NativeMessaging:
@@ -186,8 +190,17 @@ def run_dbus_monitor():
         loop = GLib.MainLoop()
         loop.run()
 
+    def register_terminate_with_parent():
+        libc = ctypes.CDLL("libc.so.6")
+        libc.prctl(PR_SET_PDEATHSIG, SIGINT, 0, 0, 0)
+
     print("Running as browser plugin.", file=sys.stderr)
     print("For interactive mode, start with --interactive", file=sys.stderr)
+
+    # on chrome and chromium, the parent process does not reliably
+    # terminate the plugin process when the parent process is killed.
+    register_terminate_with_parent()
+
     ssomib = SsoMib(daemon=True)
     ssomib.on_broker_state_changed(notify_state_change)
     monitor = Thread(target=run_dbus_monitor)