create_user_ns
extern int create_user_ns(struct cred *new);
ret = create_user_ns(new);
err = create_user_ns(cred);
ASSERT_OK(create_user_ns(), "priv new user ns");
ASSERT_EQ(create_user_ns(), EPERM, "unpriv new user ns");
ASSERT_OK(create_user_ns(), "no-bpf unpriv new user ns");