Replace ktime_get_real_seconds() with the monotonic
ktime_get_boottime_seconds() to ensure the keepalive mechanism is robust
against system clock modifications.
Right now, the driver uses ktime_get_real_seconds() to track peer
timeouts, relying on the system wall-clock.
An administrative time adjustment or an NTP sync that steps the clock
forward can cause `now' to instantly exceed `last_recv + timeout'.
When this occurs, the driver artificially expires healthy peers.
Depending on the OpenVPN user-space configuration, this triggers a
premature tunnel restart (if --keepalive or --ping-restart is used) or
a complete disconnection of the client (if --ping-exit is used).
Fixes: 3ecfd9349f ("ovpn: implement keepalive mechanism")
Signed-off-by: Marco Baffo <marco@mandelbit.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
f7e6287ccd