/usr/include/deal.II/matrix_free/ is in libdeal.ii-dev 8.5.1-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/deal.II/matrix_free/dof_info.h
/usr/include/deal.II/matrix_free/dof_info.templates.h
/usr/include/deal.II/matrix_free/evaluation_kernels.h
/usr/include/deal.II/matrix_free/fe_evaluation.h
/usr/include/deal.II/matrix_free/helper_functions.h
/usr/include/deal.II/matrix_free/mapping_data_on_the_fly.h
/usr/include/deal.II/matrix_free/mapping_info.h
/usr/include/deal.II/matrix_free/mapping_info.templates.h
/usr/include/deal.II/matrix_free/matrix_free.h
/usr/include/deal.II/matrix_free/matrix_free.templates.h
/usr/include/deal.II/matrix_free/operators.h
/usr/include/deal.II/matrix_free/shape_info.h
/usr/include/deal.II/matrix_free/shape_info.templates.h
/usr/include/deal.II/matrix_free/tensor_product_kernels.h