(6)
Federal prison system.—
Funds available to the Attorney General for the Federal Prison System may be used for—
(A)
inmate medical services and inmate legal services, within the Federal prison system;
(B)
the purchase and exchange of farm products and livestock;
(C)
the acquisition of land as provided in section
4010 of title
18; and
(D)
the construction of buildings and facilities for penal and correctional institutions (including prison camps), by contract or force account, including the payment of United States prisoners for their work performed in any such construction;
except that no funds may be used to distribute or make available to a prisoner any commercially published information or material that is sexually explicit or features nudity.