--tftp-secure
Enable TFTP secure mode: without this, any file which is readable by
the dnsmasq process under normal unix access-control rules is
available via TFTP. When the --tftp-secure flag is given, only files
owned by the user running the dnsmasq process are accessible. If
dnsmasq is being run as root, different rules apply: --tftp-secure
has no effect, but only files which have the world-readable bit set
are accessible. It is not recommended to run dnsmasq as root with TFTP
enabled, and certainly not without specifying --tftp-root. Doing so
can expose any world-readable file on the server to any host on the net.