/usr/share/kde4/apps/krita/shaders/ is in krita-data 1:2.8.1-1-0ubuntu3.
This file is owned by root:root, with mode 0o755.
..
/usr/share/kde4/apps/krita/shaders/bilinear_gradient.frag
/usr/share/kde4/apps/krita/shaders/conical_gradient.frag
/usr/share/kde4/apps/krita/shaders/conical_symetric_gradient.frag
/usr/share/kde4/apps/krita/shaders/cursor.frag
/usr/share/kde4/apps/krita/shaders/cursor.vert
/usr/share/kde4/apps/krita/shaders/highq_downscale.frag
/usr/share/kde4/apps/krita/shaders/linear_gradient.frag
/usr/share/kde4/apps/krita/shaders/matrix_transform.vert
/usr/share/kde4/apps/krita/shaders/matrix_transform_legacy.vert
/usr/share/kde4/apps/krita/shaders/radial_gradient.frag
/usr/share/kde4/apps/krita/shaders/simple_texture.frag
/usr/share/kde4/apps/krita/shaders/simple_texture_legacy.frag
/usr/share/kde4/apps/krita/shaders/square_gradient.frag