Restore default ownership in CentOS after terrible chown

"Just reinstall and be happy it wasn't a production machine?"

Yes.

rpm -a --setugids

If you happen to have an exact clone of that machine, it is possible to restore permissions using the other machine as a model. Something like:

server1:# find / /usr /home -xdev | xargs getfacl -Pp > /tmp/permissions_from_server1


server2:# setfacl --restore=/tmp/permissions_from_server1

• -xdev tells find to stay on one filesystem.
• The upper-case -P stands for Physical walk; i.e.: ignore symlinks.
• The lower-case p preserves leading slash. Without this switch, getfacl's default behavior is to remove the leading slash, causing the restore fail.

YMMV, here's a starting point.