Regarding Policy.json entries for glance image update not working for a user

Hi Team, I have a use case where I have to give a user restriction on updating the image properties as a member. I have created a policy Json file and give the modify_image rule to the particular role, but still it is not working "modify_image": "role:user", This role is created in OpenStack. but still it is failing while updating properties with a particular user assigned to a role as "access denied" and unauthorized access Regards Adivya Singh