/usr/share/dune/cmake/modules/ is in libdune-grid-dev 2.3.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/dune/cmake/modules/AddALUGridFlags.cmake
/usr/share/dune/cmake/modules/AddAlbertaFlags.cmake
/usr/share/dune/cmake/modules/AddAmiraMeshFlags.cmake
/usr/share/dune/cmake/modules/AddGrapeFlags.cmake
/usr/share/dune/cmake/modules/AddPsurfaceFlags.cmake
/usr/share/dune/cmake/modules/CheckExperimentalGridExtensions.cmake
/usr/share/dune/cmake/modules/DuneGridMacros.cmake
/usr/share/dune/cmake/modules/FindALUGrid.cmake
/usr/share/dune/cmake/modules/FindAlberta.cmake
/usr/share/dune/cmake/modules/FindAmiraMesh.cmake
/usr/share/dune/cmake/modules/FindGrape.cmake
/usr/share/dune/cmake/modules/FindPsurface.cmake
/usr/share/dune/cmake/modules/GridType.cmake
/usr/share/dune/cmake/modules/UseUG.cmake