/usr/include/CGAL/Minkowski_sum_2/ is in libcgal-dev 4.2-5ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/CGAL/Minkowski_sum_2/Approx_offset_base_2.h
/usr/include/CGAL/Minkowski_sum_2/Arr_labeled_traits_2.h
/usr/include/CGAL/Minkowski_sum_2/Decomposition_strategy_adapter.h
/usr/include/CGAL/Minkowski_sum_2/Exact_offset_base_2.h
/usr/include/CGAL/Minkowski_sum_2/Labels.h
/usr/include/CGAL/Minkowski_sum_2/Minkowski_sum_conv_2.h
/usr/include/CGAL/Minkowski_sum_2/Minkowski_sum_decomp_2.h
/usr/include/CGAL/Minkowski_sum_2/Offset_conv_2.h
/usr/include/CGAL/Minkowski_sum_2/Offset_decomp_2.h
/usr/include/CGAL/Minkowski_sum_2/Polygon_convex_decomposition.h
/usr/include/CGAL/Minkowski_sum_2/Union_of_curve_cycles_2.h
/usr/include/CGAL/Minkowski_sum_2/Union_of_cycles_2.h
/usr/include/CGAL/Minkowski_sum_2/Union_of_segment_cycles_2.h