/usr/share/gnuradio/grc/blocks/ is in gr-iio 0.2.36-2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/gnuradio/grc/blocks/iio_device_sink.xml
/usr/share/gnuradio/grc/blocks/iio_device_source.xml
/usr/share/gnuradio/grc/blocks/iio_fmcomms2_sink.xml
/usr/share/gnuradio/grc/blocks/iio_fmcomms2_source.xml
/usr/share/gnuradio/grc/blocks/iio_fmcomms5_sink.xml
/usr/share/gnuradio/grc/blocks/iio_fmcomms5_source.xml
/usr/share/gnuradio/grc/blocks/iio_math.xml
/usr/share/gnuradio/grc/blocks/iio_math_gen.xml
/usr/share/gnuradio/grc/blocks/iio_modulo_const_ff.xml
/usr/share/gnuradio/grc/blocks/iio_modulo_ff.xml
/usr/share/gnuradio/grc/blocks/iio_pluto_sink.xml
/usr/share/gnuradio/grc/blocks/iio_pluto_source.xml
/usr/share/gnuradio/grc/blocks/iio_power_ff.xml