Hi Emeric,
I'm clearly not sure that setting openssl's options to ~no-tlsxx have the same behavior than forcing the callback sets (using force-) to one protocol.
I always suspected that no-tlsxx options applies on a kind of 'capabilities' where as setting a callback-set clearly force the usage of a protocol version.
So for me the patch could modify some behavior for openssl versions < 1.1
I did not see any problems with 1.0.1, 1.0.2 documentation tends to say that it’s ok and 1.1.0 deprecated the haproxy ‘force’ implementation. At worst, this can change something in openssl 0.9.x but it's for haproxy 1.8dev… It seem that use SSL_CTX_set_options is a good compatibly choice.
The only thing i see is that no-tlsxx can generate a not recommented configuration (1.0.2). "The list of protocols available can be further limited using the SSL_OP_NO_SSLv2, SSL_OP_NO_SSLv3, SSL_OP_NO_TLSv1, SSL_OP_NO_TLSv1_1 and SSL_OP_NO_TLSv1_2options of the SSL_CTX_set_options or SSL_set_options functions. Clients should avoid creating "holes" in the set of protocols they support, when disabling a protocol, make sure that you also disable either all previous or all subsequent protocol versions. In clients, when a protocol version is disabled without disabling all previous protocol versions, the effect is to also disable all subsequent protocol versions."
Openssl introduce min-tlsxx max-tlsxx directives to avoid ‘holes’ configuration is equivalent to use SSL_CTX_set_options correctly.
There is another point which worries me:
In the proposed patch, statement 'force-' will disable all known protocol version except that one.
But we will face issue using 'force-' when openssl will support further tls versions not yet handled by haproxy. This problem was correctly handled by the previous implementation.
I agree, TLSv1.3 is missing. min-tlsxx max-tlsxx openssl directives will be a better way to no care about new version. I have a second patch who add TLSv1.3 and min-tlsxx max-tlsxx haproxy directive (patch is ssl version agnostic).
With this patches, all tls versions are supported and it’s easy to add new tls version internally. min-tlsxx and max-tlsxx is supported for all ssllibs: configuration will be more clear that with no-tlsxx and without « holes ». Add SSL_CTX_set_min/max_proto_version could be a option but i does not see the necessity.
Manu
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0001-MEDIUM-ssl-rework-of-ssl_method-calculation-to-match.patch
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0002-MEDIUM-ssl-add-TLSv1.3-directives-and-min-method-max.patch
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