crypto/tls: support kernel-provided TLS

[howardjohn]

Lots of background and a implementation, albeit from 3+ years ago: https://blog.filippo.io/playing-with-kernel-tls-in-linux-4-13-and-go/

Basically, Linux now supports handling TLS encryption in the kernel. The primary benefit here is the possibility of sendfile/splice to work with TLS. Currently, we need to choose between TLS and splice (or a custom TLS implementation, I suppose).

It would be great to have first class support in go for this.

[seankhliao]

cc @FiloSottile

[ShivanshVij]

I would love to have this happen as well! It's a major use case for L7 load balancers written in golang, and could transparently provide significant performance boosts for a lot of systems (including Kubernetes)

[FiloSottile]

Can we get some benchmarks and numbers for the performance improvement? My patch linked above might be a good starting point. It's a lot of complexity and it would have to be justified by very good numbers.

[jim3ma]

Hi, all

I have updated kernel tls support based on @FiloSottile's original code. It now supports more ciphers like AES_GCM_256, AES_CCM_128 and CHACHA20_POLY1305.

Code: https://github.com/jim3ma/go/tree/dev.ktls.1.16.3.

And I have fixed some kernel issues when in coding: torvalds/linux@974271e, torvalds/linux@d8654f4

In my simple tests, when enable kernel tls, I have got 30% time cost decreased.

[totallyunknown]

I made some real-world tests with one of our internal applications (CDN node specialised in delivering video segments for DASH and HLS streams).

• Kernel 5.13.12
• Curve: prime256v1

I compared https vs http, vs http + sendfile and ktls + sendfile.

Most of the TLS stuff is working, except TLS 1.3 with Chrome and k6. k6 reports tls: oversized record received with length 62464.

With ktls, the latency is increased - but this can also be related to the difference in the used Go-Versions.

The ktls implementation reduces overall CPU usage, around 10%. We'll deploy the Nvidia ConnectX-6 (200 Gbit/s) in our latest hardware setup, and we hope we can use the TLS NIC offloading in the future.

https://docs.google.com/spreadsheets/d/1XaiFczae9GLixu__8y2kuKPsw7RGqW9vMDkYxuTLx28/edit#gid=0

[jrfastab]

@totallyunknown If the latency issue is related to the kernel implementation (rule out golang side) we can take a look at kernel side improvements. We've been using the openssl implementation lately so I'll check there as well, but I don't recall extra latency last time I did metrics. Having a golang implementation would be very useful on my side as well. fwiw I'm one of the ktls maintainers on kernel side so we shouldn't have trouble getting improvements there as needed and happy to help where I can to get this moving forward.

[jim3ma]

I made some real-world tests with one of our internal applications (CDN node specialised in delivering video segments for DASH and HLS streams).

• Kernel 5.13.12
• Curve: prime256v1

I compared https vs http, vs http + sendfile and ktls + sendfile.

Most of the TLS stuff is working, except TLS 1.3 with Chrome and k6. k6 reports tls: oversized record received with length 62464.

With ktls, the latency is increased - but this can also be related to the difference in the used Go-Versions.

The ktls implementation reduces overall CPU usage, around 10%. We'll deploy the Nvidia ConnectX-6 (200 Gbit/s) in our latest hardware setup, and we hope we can use the TLS NIC offloading in the future.

https://docs.google.com/spreadsheets/d/1XaiFczae9GLixu__8y2kuKPsw7RGqW9vMDkYxuTLx28/edit#gid=0

Which version do you test ? I have update some go code for http with ktls.

[totallyunknown]

@jim3ma Your branch: https://github.com/jim3ma/go/tree/dev.ktls.1.16.3

[jim3ma]

@jim3ma Your branch: https://github.com/jim3ma/go/tree/dev.ktls.1.16.3

Okay, I will merge some optimized code into this branch tomorrow.

[kkkygytb]

Excuse me, how is the implementation going?