tls: add version-specific cipher suite options

[MrAnno]

OpenSSL/libcurl use a separate method for setting TLS 1.3 ciphers to be backward
compatible with older versions/configurations.

This PR adds version-specific cipher-suite() options, for example:

cipher-suite(tls12-and-older("list:of:ciphers"), tls13("list:of:ciphers"))

tls12-and-older() can be used for specifying ciphers for TLS v1.2-and-older,
tls13() can be used to specify TLS v1.3 ciphers.

Note:
For backward compatibility cipher-suite("list:of:ciphers") restricts only the TLSv1.2-and-older cipher suite.

Fixes #3906

[kira-syslogng]

Build SUCCESS

[kira-syslogng]

Build SUCCESS

[MrAnno]

Should we allow cipher-suite("list:of:old:ciphers", tls13("list:of:new:ciphers")) too (mixing the compat method with the new)?

[bazsi]

I would not, the old syntax is for the legacy case, when converting it is much clearer if they specify the versions explicitly. Random thinking: One thing that came to mind is the naming of the embedded options, it is true that the boundary is with TLS1.3 but I guess we will have TLS1.4 and TLS2.0 eventually and don't anticipate changes in the cipher-suite options by then. Also, the old one is not just for TLS1.2, but for anything between SSL1..TLS1.2. The difficulty lies in the names themselves, I somewhat like "legacy" for the old cipher suites but what is the opposite of "legacy"? hmmm... apache does this: https://httpd.apache.org/docs/2.4/mod/mod_ssl.html#sslciphersuite It allows specifying "protocol" in the SSLCipherSuite directive, "SSL" denoting everything between SSL1 .. TLS1.2 and "TLSv1.3" denoting the new ciphersuites. If you omit "protocol" you would get SSL (for compatibility with old config), if you use "DEFAULT" it would use the version that openssl/apache combination defaults to (which might generate a configuration failure when the switch in default happens) nginx does not seem to support this yet and is using the ssl config file to force cipher suites. Maybe I would use ssl() for the legacy ciphersuites and tls13() for the new ones. Eventually if the latter becomes a "span" of versions we could maybe call that simply tls() or wait for Apache to name this. I am not sure about the "DEFAULT" case, whether we need it at all. What happens is once the flip to TLS1.3 as default happens, the ciphersuites would become uncontrolled and TLS1.3 would start using its defaults. If we added "DEFAULT", then the cipher suite could either denote the SSL ciphers or the TLS1.3 ciphers. At the time of the switch we would generate a startup failure, as we would try to supply an SSL cipher suite to a TLS version or vice versa. Maybe a good discussion for our upcoming jit.si meeting?

…

On Wed, Feb 9, 2022 at 8:34 PM László Várady ***@***.***> wrote: Should we allow cipher-suite("list:of:old:ciphers", tls13("list:of:new:ciphers")) too (mixing the compat method with the new)? — Reply to this email directly, view it on GitHub <#3907 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAFOK5THLPO3DZ3RR2SOL2TU2K6TLANCNFSM5N6ABFIQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

-- Bazsi

[MrAnno]

jit.si meeting results:

We decided to use longer but accurate names, for example:
tls12-and-older() and tls13()

If our assumption is correct, OpenSSL will not add a third separated method for new TLS versions, so in case of a theoretical TLS 1.4 or 2.0 version, we could just add an alias for tls13(): tls13-and-newer. If we turn out to be wrong, we can still add new versioned options.

[MrAnno]

Done.

@bazsi Could you review this, please?

[kira-syslogng]

Build SUCCESS

[MrAnno]

@kira-syslogng do stresstest

[kira-syslogng]

Kira-stress-test: Build SUCCESS

[kira-syslogng]

Build SUCCESS

[OverOrion]

LGTM!

[alltilla]

Checked the other tls() implementations: riemann() and amqp().
They do not have cipher suite setter options, so these changes are not applicable there.

Approve!