Cal. PEN § 4573.8

Any person who knowingly has in his or her possession in any state prison, prison road camp, prison forestry camp, or other prison camp or prison farm or any place where prisoners of the state are located under the custody of prison officials, officers, or employees, or in any county, city and county, or city jail, road camp, farm, or any place or institution, where prisoners or inmates are being held under the custody of any sheriff, chief of police, peace officer, probation officer, or employees, or within the grounds belonging to any jail, road camp, farm, place, or institution, drugs in any manner, shape, form, dispenser, or container, any device, contrivance, instrument, or paraphernalia intended to be used for unlawfully injecting or consuming drugs, or alcoholic beverages, without being authorized to possess the same by rules of the Department of Corrections, rules of the prison or jail, institution, camp, farm, or place, or by the specific authorization of the warden, superintendent, jailer, or other person in charge of the prison, jail, institution, camp, farm, or place, is guilty of a felony.

The prohibitions and sanctions addressed in this section shall be clearly and prominently posted outside of, and at the entrance to, the grounds of all detention facilities under the jurisdiction of, or operated by, the state or any city, county, or city and county.