I think that detection of source/destination mac addresses of a packet is done after NF_IP_POST_ROUTING step of Netfilter. Is it possible to hook the packet after this step with correct mac addresses? I want to decide about outgoing packets from my NIC to drop/accept them. I think it is like a firewall on outgoing packets. I studied many firewall codes but they usually work on NF_IP_PRE_ROUTING.

I must say I do not understand the situation you describe. You want to drop packets you're about to send? If so, postrouting seems to be the place to deal with it. You already know the interface.

Firewalls usually work on prerouting, because they filter the packets that are coming in, not those going out (which were handled earlier).

Thanks for your attention to my question. When I get a packet in post-routing step, the packet has no src/dst mac addresses and after this step, src/dst mac addresses will set according to the route tables. I want to hook a packet with its correct src/dst mac addresses.
In my project, I want to get all receiving/sending packets from/to the NIC and send them to the userspace app (with NETLINK) and drop thems. So all receiving packets from NIC should be received by my kernel module and after calling my kernel module the receive packet should be droped. Also when a packet is ready for sending to NIC, my kernel module should hook and drop them. In my kernel module a copy of packet (sk_buff) is sent to an userspace app with NETLINK.
In userspace app I should do some special works on the received sk_buff from kernel module with its direction.
I think there is no way to hook a packet after port-routing step of netfilter with its src/dst mac addresses. I think I should rewrite and customize the dev_queue_xmit function.

If you really want the packet with MAC, you'll have to add your own hook. I'm just wondering if you really need it - you know it will have the right one.