You don't need to create your own kernel modules to define custom packet processing logic. You can map an RX/TX ring into userspace memory by invoking setsockop

You don't need to create your own kernel modules to define custom packet processing logic. You can map an RX/TX ring into userspace memory by invoking setsockopt on your XDP socket with the XDP_RX_RING, XDP_TX_RING and XDP_UMEM_REG options. Your XDP BPF program can then choose to redirect an incoming packet to the RX ring (see BPF_MAP_TYPE_XSKMAP).