/usr/include/deal.II/grid/ is in libdeal.ii-dev 8.4.2-2+b1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/deal.II/grid/cell_id.h
/usr/include/deal.II/grid/filtered_iterator.h
/usr/include/deal.II/grid/grid_generator.h
/usr/include/deal.II/grid/grid_in.h
/usr/include/deal.II/grid/grid_out.h
/usr/include/deal.II/grid/grid_refinement.h
/usr/include/deal.II/grid/grid_reordering.h
/usr/include/deal.II/grid/grid_reordering_internal.h
/usr/include/deal.II/grid/grid_tools.h
/usr/include/deal.II/grid/intergrid_map.h
/usr/include/deal.II/grid/magic_numbers.h
/usr/include/deal.II/grid/manifold.h
/usr/include/deal.II/grid/manifold_lib.h
/usr/include/deal.II/grid/persistent_tria.h
/usr/include/deal.II/grid/tria.h
/usr/include/deal.II/grid/tria_accessor.h
/usr/include/deal.II/grid/tria_accessor.templates.h
/usr/include/deal.II/grid/tria_boundary.h
/usr/include/deal.II/grid/tria_boundary_lib.h
/usr/include/deal.II/grid/tria_faces.h
/usr/include/deal.II/grid/tria_iterator.h
/usr/include/deal.II/grid/tria_iterator.templates.h
/usr/include/deal.II/grid/tria_iterator_base.h
/usr/include/deal.II/grid/tria_iterator_selector.h
/usr/include/deal.II/grid/tria_levels.h
/usr/include/deal.II/grid/tria_object.h
/usr/include/deal.II/grid/tria_objects.h