Socket implementation in Linux Kernel

Socket implementation in Linux kernel-general Linux technology-Linux programming and kernel information. For details, refer to the following section. In the Linux kernel environment, AF_UNIX socket is established to implement communication between the user layer and the kernel through send and recv, such as ioctl and netlink.
Question 1: What code does the kernel implement to communicate with the user layer? How does the kernel differentiate AF_UNIX socket instead of AF_INET? Does the send and recv operations of different sockets share the same kernel code?
Question 2: Can I use the AF_UNIX socket to implement custom commands to allow users to communicate with the kernel, similar to ioctl and netlink? Is there any idea?
Please kindly advise them.