[$] Offload-friendly network encryption in the kernel

ThePSP security protocol (PSP) is a way to transparently encrypt packets byefficiently offloading encryption and decryption to the networkinterface cards (NICs) that Google uses for connections inside its data centers. Theprotocol is similar toIPsec, in that it allows for wrapping arbitrary trafficin a layer of encryption. The difference is that PSP is encapsulated in UDP, anddesigned from the beginning to reduce the amount of state that NICshave to track in order to send and receive encrypted traffic, allowing for moresimultaneous connections. Jakub Kicinskiwants to add support for the protocol to the Linux kernel.