/usr/include/libnl3/netlink/route/link/ is in libnl-3-dev 3.2.27-1ubuntu0.16.04.1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libnl3/netlink/route/link/api.h
/usr/include/libnl3/netlink/route/link/bonding.h
/usr/include/libnl3/netlink/route/link/bridge.h
/usr/include/libnl3/netlink/route/link/can.h
/usr/include/libnl3/netlink/route/link/inet.h
/usr/include/libnl3/netlink/route/link/inet6.h
/usr/include/libnl3/netlink/route/link/info-api.h
/usr/include/libnl3/netlink/route/link/ip6tnl.h
/usr/include/libnl3/netlink/route/link/ipgre.h
/usr/include/libnl3/netlink/route/link/ipip.h
/usr/include/libnl3/netlink/route/link/ipvlan.h
/usr/include/libnl3/netlink/route/link/ipvti.h
/usr/include/libnl3/netlink/route/link/macvlan.h
/usr/include/libnl3/netlink/route/link/sit.h
/usr/include/libnl3/netlink/route/link/veth.h
/usr/include/libnl3/netlink/route/link/vlan.h
/usr/include/libnl3/netlink/route/link/vxlan.h