Ability to limit supported TLS versions and disable certain versions

[sgringwe]

PCI compliance states that TLS 1.0 cannot be enabled starting June 2018 (https://blog.pcisecuritystandards.org/are-you-ready-for-30-june-2018-sayin-goodbye-to-ssl-early-tls).

It'd be great to have a way to disable TLS 1.0 in Contour or generally configure supported versions.

[davecheney]

This is a very good idea. Currently the tls_params field in the listener's TLS context is not specified so I'm guessing it defaults to whatever the default of the ssl library that Envoy links against.

This isn't great (and it isn't great to guess).

What I think we should do is twofold

• send a PR to provide a reasonably modern tls_params set of parameters. The values of reasonable and modern can be negotiated later. My view is the cipher suite params should tend towards the restrictive.
• iff we get bug reports that people can't use insecure versions of browsers and appliances to communicate with their applications, we can add the ability to specify the params suite as an annotation to the ingress object.

[sevein]

The default ciphers and curves in Envoy seem pretty sane to me.

Regarding to the protocols supported, the following table shows the current defaults and the change that I would like to suggest:

Property	Envoy's interpretation of zero value	Suggested change
TlsParameters.TlsMinimumProtocolVersion	TLS 1.0	TLS 1.1
TlsParameters.TlsMaximumProtocolVersion	TLS 1.2	None

Support for annotations in the ingress object would be great in the long term!

[davecheney]

Some work on this was done in 0.4 by @sevein. We might do more in 0.5.

[davecheney]

Nothing to do for 0.5, bumping to 0.6