/usr/share/man/man5/sanewall-mark-param.5.gz is in sanewall-doc 1.0.2+ds-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man5/sanewall-rule-params.5.gz
/usr/share/man/man5/sanewall-rule-params.5.gz