/usr/include/fst/extensions/far/ is in libfst-dev 1.6.3-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/fst/extensions/far/compile-strings.h
/usr/include/fst/extensions/far/create.h
/usr/include/fst/extensions/far/equal.h
/usr/include/fst/extensions/far/extract.h
/usr/include/fst/extensions/far/far-class.h
/usr/include/fst/extensions/far/far.h
/usr/include/fst/extensions/far/farlib.h
/usr/include/fst/extensions/far/farscript.h
/usr/include/fst/extensions/far/getters.h
/usr/include/fst/extensions/far/info.h
/usr/include/fst/extensions/far/isomorphic.h
/usr/include/fst/extensions/far/print-strings.h
/usr/include/fst/extensions/far/script-impl.h
/usr/include/fst/extensions/far/stlist.h
/usr/include/fst/extensions/far/sttable.h