/usr/include/infiniband/opensm/ is in libopensm-dev 3.3.15-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/infiniband/opensm/osm_attrib_req.h
/usr/include/infiniband/opensm/osm_base.h
/usr/include/infiniband/opensm/osm_config.h
/usr/include/infiniband/opensm/osm_congestion_control.h
/usr/include/infiniband/opensm/osm_console.h
/usr/include/infiniband/opensm/osm_console_io.h
/usr/include/infiniband/opensm/osm_db.h
/usr/include/infiniband/opensm/osm_db_pack.h
/usr/include/infiniband/opensm/osm_errors.h
/usr/include/infiniband/opensm/osm_event_plugin.h
/usr/include/infiniband/opensm/osm_file_ids.h
/usr/include/infiniband/opensm/osm_guid.h
/usr/include/infiniband/opensm/osm_helper.h
/usr/include/infiniband/opensm/osm_inform.h
/usr/include/infiniband/opensm/osm_lid_mgr.h
/usr/include/infiniband/opensm/osm_log.h
/usr/include/infiniband/opensm/osm_mad_pool.h
/usr/include/infiniband/opensm/osm_madw.h
/usr/include/infiniband/opensm/osm_mcast_tbl.h
/usr/include/infiniband/opensm/osm_mcm_port.h
/usr/include/infiniband/opensm/osm_mesh.h
/usr/include/infiniband/opensm/osm_msgdef.h
/usr/include/infiniband/opensm/osm_mtree.h
/usr/include/infiniband/opensm/osm_multicast.h
/usr/include/infiniband/opensm/osm_node.h
/usr/include/infiniband/opensm/osm_opensm.h
/usr/include/infiniband/opensm/osm_partition.h
/usr/include/infiniband/opensm/osm_path.h
/usr/include/infiniband/opensm/osm_perfmgr.h
/usr/include/infiniband/opensm/osm_perfmgr_db.h
/usr/include/infiniband/opensm/osm_pkey.h
/usr/include/infiniband/opensm/osm_port.h
/usr/include/infiniband/opensm/osm_port_profile.h
/usr/include/infiniband/opensm/osm_prefix_route.h
/usr/include/infiniband/opensm/osm_qos_policy.h
/usr/include/infiniband/opensm/osm_remote_sm.h
/usr/include/infiniband/opensm/osm_router.h
/usr/include/infiniband/opensm/osm_sa.h
/usr/include/infiniband/opensm/osm_sa_mad_ctrl.h
/usr/include/infiniband/opensm/osm_service.h
/usr/include/infiniband/opensm/osm_sm.h
/usr/include/infiniband/opensm/osm_sm_mad_ctrl.h
/usr/include/infiniband/opensm/osm_stats.h
/usr/include/infiniband/opensm/osm_subnet.h
/usr/include/infiniband/opensm/osm_switch.h
/usr/include/infiniband/opensm/osm_ucast_cache.h
/usr/include/infiniband/opensm/osm_ucast_lash.h
/usr/include/infiniband/opensm/osm_ucast_mgr.h
/usr/include/infiniband/opensm/osm_version.h
/usr/include/infiniband/opensm/osm_vl15intf.h
/usr/include/infiniband/opensm/st.h