Sessions monitor should watch only changes in sessions #445
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Currently, the polkitbackendsessionmonitor watches all notifications from sd-login-monitor. This causes waking polkit even four+ times on every login/logout and starting a train of action re-verification several times for each instantiated PolkitAuthority (e.g. applets on gnome-shell panel that utilize PolkitPermission). This is not necessary, because polkit only needs to watch for sessions that change status from active to online and vice-versa (to maintain security for actions that have is_active defined). This still doesn't resolve the problem completely, but at least halves the impact on system resources.
bluca
approved these changes
Apr 22, 2024
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Summary
Currently, the polkitbackendsessionmonitor watches all notifications from sd-login-monitor. This causes waking polkit even four+ times on every login/logout and starting a train of action re-verification several times for each instantiated PolkitAuthority (e.g. applets on gnome-shell panel that utilize PolkitPermission).
This is not necessary, because polkit only needs to watch for sessions that change status from active to online and vice-versa (to maintain security for actions that have is_active defined). This still doesn't resolve the problem completely, but at least halves the impact on system resources.
Detailed description and/or reproducer
On a gnome-shell-fitted system, set dbus-monitor to listen on PolicyKit1.Authority interface and watch the flood on login/logout (e.g. via ssh):
"# dbus-monitor --system "interface=org.freedesktop.PolicyKit1.Authority"
On each signal from logind (uids, seats, sessions,...), polkitbackend sends "Changed" over dbus. The signal is caught by every PolkitAuthority instance and triggers authorization re-check by sending "CheckAuthorization" back to polkitbackend.