The configuration and especially right permissions will be done in /etc/rsyslog.conf
Bitmask is going to be used so use this doc http://www.cyberciti.biz/faq/unix-linux-bsd-chmod-numeric-permissions-notation-command/
It will be taken into account for the new log files only when we reload rsylog with this commend:
The old files are still on the old configuration. So, you need to change the right access directly for them with chown and chmod.
Example for vagrant user:
[email protected]:/var/log/openerp# chown vagrant:vagrant /var/log/openerp/ -R [email protected]:/var/log/openerp# chmod a+r /var/log/openerp/ -R