Seen karmafarming posts. Is it against the rules or just frowned upon?

Basically the title.

I've seen a couple karma farming posts and comments lately and was having a look at reddit's rules, in this sub and newtoreddit but couldn't find whether it is just frowned upon, against a couple subreddit rules that specifically state that or a sitewide rule (also because I think the search results aren't too helpful but that's besides the point).

I was thinking just frowned upon because the mods of these subs do not seem to mind but I am not sure