Drug culture, b’derech klall, is very verbotten in Yeshivas. Smoking and drinking are completely different stories. In some Yeshivas (especially in Eretz Yisroel), bachurim are peer pressured into smoking, some just the opposite.
There are several Yeshivas which are open to former drug addicts, but they are not made up exclusively of that crowd. There are also several Yeshivas/Rehab centers open for current drug users. The top guys from the latter type places end up in the former type of place.
Drug smuggling and subsequent abuse are also major problems in certain Yeshivas (again, mostly in Eretz Yisroel). In general the boys have no idea what drugs are or what is in the package that someone just paid them $1000 to deliver to Antwerp. It happens a lot more often than people like to admit, and often the predators who enlist these boys go unpunished if the boys aren’t caught by the Japanese police. It’s not unheard of for these boys to end up addicted themselves once they’ve become “experts” at smuggling.