The Second Amendment of the United States:
A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms shall not be infringed.
United States Congressional Law:
Gun Free Zones Act as passed by the 101st Congress Bill 2070, the text is very long, link goes directly to bill. I'm not sure how this infringement was allowed to pass muster, as the words "Shall not be infringed" seems pretty simple, without room for this type of direct infringement.
State Law, Missouri Section 571.107.10:
Any higher education institution or elementary or secondary school facility without the consent of the governing body of the higher education institution or a school official or the district school board, unless the person with the concealed carry endorsement or permit is a teacher or administrator of an elementary or secondary school who has been designated by his or her school district as a school protection officer and is carrying a firearm in a school within that district, in which case no consent is required. Possession of a firearm in a vehicle on the premises of any higher education institution or elementary or secondary school facility shall not be a criminal offense so long as the firearm is not removed from the vehicle or brandished while the vehicle is on the premises;
The 2nd Amendment is seen by the Supreme Court as an acknowledgement of an existing right of the individual:
...in District of Columbia v. Heller 12 confirmed what had been a growing consensus of legal scholars—that the rights of the Second Amendment adhered to individuals. The Court reached this conclusion after a textual analysis of the Amendment,13 an examination of the historical use of prefatory phrases in statutes, and a detailed exploration of the 18th century meaning of phrases found in the Amendment. (https://www.congress.gov/content/conan/pdf/GPO-CONAN-2017-10-3.pdf)
The 101st Congressional Bill was passed directly impacting these rights, and had been determined unconstitutional in the case before the Supreme Court, United States v. Lopez, 514 U.S. 549 (https://www.law.cornell.edu/supct/html/93-1260.ZO.html), consequently Congress made slight modifications to the law, and it has not been re-tested in the Supreme Court to date.
The Missouri law has not been tested in State or Federal Supreme Courts.