r0 = openat$tun(0xffffffffffffff9c, &(0x7f00000001c0), 0x0, 0x0)
r1 = socket$inet(0x2, 0xa, 0x0)
r2 = dup3(r1, r0, 0x0)
getsockopt$sock_buf(r2, 0x1, 0x1c, 0x0, &(0x7f0000000340))