/lib/udev/rules.d/40-fpga-icestorm.rules is in fpga-icestorm 0~20151006git103e6fd-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6010", MODE="0660", GROUP="plugdev"
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