Cal. PEN § 4573.9

(a) Notwithstanding any other provision of law, any person, other than a person held in custody, who sells, furnishes, administers, or gives away, or offers to sell, furnish, administer, or give away to any person held in custody in any state prison or other institution under the jurisdiction of the Department of Corrections, or in any prison camp, prison farm, or any other place where prisoners or inmates of these institutions are located under the custody of prison institution officials, officers, or employees, or in any county, city and county, or city jail, road camp, farm, or any other institution or place 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 institution or place, any controlled substance, the possession of which is prohibited by Division 10 (commencing with Section 11000) of the Health and Safety Code, if the recipient is not authorized to possess the same by the 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 punishable by imprisonment pursuant to subdivision (h) of Section 1170 for two, four, or six years.

(b) 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.