/usr/src/xtables-addons-1.40/ipset-6/include/ is in xtables-addons-dkms 1.40-1.
This file is owned by root:root, with mode 0o755.
..
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/data.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/debug.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/errcode.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/icmp.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/icmpv6.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/linux_ip_set.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/linux_ip_set_bitmap.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/linux_ip_set_hash.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/linux_ip_set_list.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/mnl.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/nf_inet_addr.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/nfproto.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/parse.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/pfxlen.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/print.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/session.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/transport.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/types.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/ui.h
/usr/src/xtables-addons-1.40/ipset-6/include/libipset/utils.h