/usr/include/linbox/ring/ is in liblinbox-dev 1.4.2-5build1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/linbox/ring/abstract.h
/usr/include/linbox/ring/archetype.h
/usr/include/linbox/ring/envelope.h
/usr/include/linbox/ring/givaro-poly.h
/usr/include/linbox/ring/givaro-polynomial.h
/usr/include/linbox/ring/local-pir-modular.h
/usr/include/linbox/ring/local2_32.h
/usr/include/linbox/ring/modular/
/usr/include/linbox/ring/modular.h
/usr/include/linbox/ring/modular/modular-balanced-double.h
/usr/include/linbox/ring/modular/modular-balanced-float.h
/usr/include/linbox/ring/modular/modular-balanced-int32.h
/usr/include/linbox/ring/modular/modular-balanced-int64.h
/usr/include/linbox/ring/modular/modular-byte.h
/usr/include/linbox/ring/modular/modular-double.h
/usr/include/linbox/ring/modular/modular-float.h
/usr/include/linbox/ring/modular/modular-int32.h
/usr/include/linbox/ring/modular/modular-int64.h
/usr/include/linbox/ring/modular/modular-short.h
/usr/include/linbox/ring/modular/modular-unsigned.h
/usr/include/linbox/ring/ntl/
/usr/include/linbox/ring/ntl.h
/usr/include/linbox/ring/ntl/ntl-gf2e.h
/usr/include/linbox/ring/ntl/ntl-lzz_p.h
/usr/include/linbox/ring/ntl/ntl-lzz_pe.h
/usr/include/linbox/ring/ntl/ntl-lzz_pex.h
/usr/include/linbox/ring/ntl/ntl-lzz_px.h
/usr/include/linbox/ring/ntl/ntl-rr.h
/usr/include/linbox/ring/ntl/ntl-zz.h
/usr/include/linbox/ring/ntl/ntl-zz_p.h
/usr/include/linbox/ring/ntl/ntl-zz_pe.h
/usr/include/linbox/ring/ntl/ntl-zz_px.h
/usr/include/linbox/ring/pid-ntl-zz_p.h
/usr/include/linbox/ring/pir-modular-int32.h
/usr/include/linbox/ring/pir-ntl-zz_p.h
/usr/include/linbox/ring/poweroftwomodular.h
/usr/include/linbox/ring/ring-interface.h