jls(8) is trivially capsicumized (same as yes(1)).
However: libjail uses sysctll(3) on the security.jail.param tree (to discover jail parameters) as well as jail_get(2).
- CTLFLAG_CAPRD all security.jail.param sysctls
- whitelist jail_get in capabilities.conf
need to regen sys/kern/init_sysent.c (make sysent)