fubarnetes / kmod_devctl_jail

Kernel module providing devctl notifications for jails

devctl_jail.ko

Kernel module providing devctl notifications for jails.

Is it any good?

Yes.

But how do I use it?

Build devctl_jail.ko with make and load the kernel module as root using kldload ./devctl_jail.ko. If you want, you can install it by running make install as root.

This kernel module ships with an example devd.conf and syslogd.conf which add some logging functionality. Install them and restart devd and syslogd:

cp syslogd.conf /usr/local/etc/syslog.d/jail.conf
touch /var/log/jail
systemctl restart syslogd
cp devd.conf /usr/local/etc/devd/jail.conf
service restart devd

This will give you some logging that looks like this:

May 20 20:50:05 blackbox jail[50581]: Jail JID=1 created
May 20 20:50:08 blackbox jail[50592]: Process PID=50591 attached to Jail JID=1
May 20 20:50:54 blackbox jail[50626]: Jail JID=1 removed

If you are writing a jail manager however, you might be interested in getting the notifications yourself. You can just connect to the SOCK_SEQPACKET socket at /var/run/devd.seqpacket.pipe to receive raw notifications multiplexed by devd.