QUIC for the Kernel

9 months ago

QUIC was created to address latency and performance issues with TCP, such as the three-way handshake and head-of-line blocking.
TCP's metadata is transmitted in the clear, leading to information leaks and protocol ossification, making it hard to improve.
QUIC eliminates the three-way handshake, supports multiple streams, and encrypts transport data to prevent middlebox interference.
QUIC is specified in RFC 9000 and RFC 9369, widely supported in user space, but kernel implementations are now being considered for better performance.
The kernel patch introduces IPPROTO_QUIC, integrates TLS for encryption, and uses libquic and tlshd for setup, caching TLS negotiation results for faster subsequent connections.
Current benchmarks show in-kernel QUIC underperforming compared to in-kernel TLS and TCP, but future hardware support and optimizations are expected to improve performance.
Interest in kernel-based QUIC is growing, with support being added to Samba, curl, and potential future applications.
The QUIC implementation in the kernel is in early stages, with significant code review expected, and mainline inclusion likely not before 2026.

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