Dnsmasq: cannot open log /var/log/pihole.log: Permission denied

Once you have the constraints set on that file, then it should start up with no problems. Since it's modifying the security of the operating system, we decided a few releases back to just warn the user and let them modify if they chose, instead of installing a custom security policy. If we can be of assistance, let us know, however the latest policy that we have needs to be tuned and cleaned up, it was a little too permissive for our likes.