doc: default cipher suite docs are misleading for server and client context

[desimone]

Title: default cipher suite docs are misleading for server and client context

Description:

The default tls client config has changed since v1.16 to be distinct from the default server config.

From

envoy/source/extensions/transport_sockets/tls/context_config_impl.cc

Lines 332 to 356 in bf5d0eb

	const std::string ClientContextConfigImpl::DEFAULT_CIPHER_SUITES =
	#ifndef BORINGSSL_FIPS
	"[ECDHE-ECDSA-AES128-GCM-SHA256|ECDHE-ECDSA-CHACHA20-POLY1305]:"
	"[ECDHE-RSA-AES128-GCM-SHA256|ECDHE-RSA-CHACHA20-POLY1305]:"
	#else // BoringSSL FIPS
	"ECDHE-ECDSA-AES128-GCM-SHA256:"
	"ECDHE-RSA-AES128-GCM-SHA256:"
	#endif
	"ECDHE-ECDSA-AES128-SHA:"
	"ECDHE-RSA-AES128-SHA:"
	"AES128-GCM-SHA256:"
	"AES128-SHA:"
	"ECDHE-ECDSA-AES256-GCM-SHA384:"
	"ECDHE-RSA-AES256-GCM-SHA384:"
	"ECDHE-ECDSA-AES256-SHA:"
	"ECDHE-RSA-AES256-SHA:"
	"AES256-GCM-SHA384:"
	"AES256-SHA";
	const std::string ClientContextConfigImpl::DEFAULT_CURVES =
	#ifndef BORINGSSL_FIPS
	"X25519:"
	#endif
	"P-256";

To

envoy/source/extensions/transport_sockets/tls/context_config_impl.cc

Lines 315 to 331 in ce071f6

	const std::string ClientContextConfigImpl::DEFAULT_CIPHER_SUITES =
	#ifndef BORINGSSL_FIPS
	"[ECDHE-ECDSA-AES128-GCM-SHA256|ECDHE-ECDSA-CHACHA20-POLY1305]:"
	"[ECDHE-RSA-AES128-GCM-SHA256|ECDHE-RSA-CHACHA20-POLY1305]:"
	#else // BoringSSL FIPS
	"ECDHE-ECDSA-AES128-GCM-SHA256:"
	"ECDHE-RSA-AES128-GCM-SHA256:"
	#endif
	"ECDHE-ECDSA-AES256-GCM-SHA384:"
	"ECDHE-RSA-AES256-GCM-SHA384:";
	const std::string ClientContextConfigImpl::DEFAULT_CURVES =
	#ifndef BORINGSSL_FIPS
	"X25519:"
	#endif
	"P-256";

This is not clear in the docs.

For example, where tls_minimum_protocol_version / tls_maximum_protocol_version explicitly mention the difference in client and server configs, cipher_suites does not.

If you agree, I'd be happy to make this change / update the docs to be more clear that the new default client cipher suite is as follows.

[ECDHE-ECDSA-AES128-GCM-SHA256|ECDHE-ECDSA-CHACHA20-POLY1305]
[ECDHE-RSA-AES128-GCM-SHA256|ECDHE-RSA-CHACHA20-POLY1305]
ECDHE-ECDSA-AES256-GCM-SHA384
ECDHE-RSA-AES256-GCM-SHA384

Related context

• proxy / controplane: unexpected change in default client TLS context pomerium/pomerium#2195
• Modernize TLS defaults #5401
• tls: remove deprecated cipher suites from client defaults. #13850
• Remove RSA key transport from the defaults on the client-side #5396
• Remove SHA-1 cipher suites from the defaults on the client-side #5397

[antoniovicente]

@PiotrSikora @ggreenway @phlax

You're right, the client cipher list changed due to #13850

We'ld be happy to accept PRs to update the docs so they are more correct and clear.