§ 102-74.400 What is the policy concerning the possession and use of narcotics and other drugs?
Except in cases where the drug is being used as prescribed for a patient by a licensed physician, all persons entering in or on Federal property are prohibited from—
(a) Being under the influence, using or possessing any narcotic drugs, hallucinogens, marijuana, barbiturates, or amphetamines; or
(b) Operating a motor vehicle on the property while under the influence of alcoholic beverages, narcotic drugs, hallucinogens, marijuana, barbiturates, or amphetamines.
https://www.ecfr.gov/current/title-41/subtitle-C/chapter-102/subchapter-C/part-102-74/subpart-C
The drug has to come from somewhere else which adds the trafficking element to it.
Just possession I'm afraid. At least getting caught on non federal land this would just be a possession charge. One baggy, personal amount. Misdemeanor. In my state you would be able to keep it and run free SMH