Allow charon to start as a non-root user without CAP_CHOWN and still be
able to change the group on files that need to be accessed by charon
after capabilities have been dropped. This requires the user charon starts
as to have access to socket/pidfile directory as well as belong to the
group that charon will run as after dropping capabilities.
Closesstrongswan/strongswan#105.
This patch allows for giving strongSwan only the runtime capabilities it
needs, rather than full root privileges.
Adds preprocessor directives which allow strongSwan to be configured to
1) start up as a non-root user
2) avoid modprobe()'ing IPsec kernel modules into the kernel, which
would normally require root or CAP_SYS_MODULE
Additionally, some small mods to charon/libstrongswan ensure that charon
fully supports starting as a non-root user.
Tested with strongSwan 5.5.3.
Micah Morton