In [1] a workaround for those (hopefully a few) installations that need the lower (not recommended) key size was suggested.
Again this isn't what "should be done", but what users could do if affected. The reason not to do it is: a) LOGJAM (CVE-2015-4000), common prime: HAProxy (1024 bits) b) due to that haproxy always warned you: "[WARNING] 286/090504 (13834) : Setting tune.ssl.default-dh-param to 1024 by default, if your workload permits it you should set it to at least 2048. Please set a value >= 1024 to make this warning disappear." So we actually want and think it is good that the default size got bumped. But people that need the old smaller key size (like David in comment #11) need to have a way to drop back to the old key size. With haproxy and testssl I checked (again) Bionic as-is: updates (1.8.8-1ubuntu0.4) DH group offered: HAProxy (1024 bits) proposed (1.8.8-1ubuntu0.5): DH group offered: RFC5114/2048-bit DSA group with 224-bit prime order subgroup (2048 bits) proposed (1.8.8-1ubuntu0.5) + seclevel 0/1 config: :-/ I Failed to convince haproxy from using any config in that regard. Tried several combinations of "CipherString = DEFAULT@SECLEVEL=0" in /etc/ssl/openssl.cnf Tried to get it into /etc/haproxy/haproxy.cfg But none worked to get the key size down This might be my lack of haproxy experience. I tried some combinations that came to my mind and asked in the IRC channel or haproxy, but got no response. If someone could take a look that knows haproxy better. Maybe we can release this fix for TLSv1.3 IF there is a configuration workaround for the few people that need the small (vulnreable) key size. [1]: https://lists.ubuntu.com/archives/ubuntu- devel/2019-October/040814.html -- You received this bug notification because you are a member of Ubuntu High Availability Team, which is subscribed to haproxy in Ubuntu. https://bugs.launchpad.net/bugs/1841936 Title: Rebuild haproxy with openssl 1.1.1 will change features (bionic) Status in haproxy package in Ubuntu: Fix Released Status in haproxy source package in Bionic: Fix Committed Bug description: [Impact] * openssl 1.1.1 has been backported to Bionic for its longer support upstream period * That would allow the extra feature of TLSv1.3 in some consuming packages what seems "for free". Just with a no change rebuild it would pick that up. [Test Case] * run "haproxy -vv" and check the reported TLS versions to include 1.3 [Regression Potential] * This should be low, the code already runs against the .so of the newer openssl library. This would only make it recognize the newer TLS support. i'd expect more trouble as-is with the somewhat big delta between what it was built against vs what it runs with than afterwards. * [1] and [2] indicate that any config that would have been made for TLSv1.2 [1] would not apply to the v1.3 as it would be configured in [2]. It is good to have no entry for [2] yet as following the defaults of openssl is the safest as that would be updated if new insights/CVEs are known. But this could IMHO be the "regression that I'd expect", one explcitly configured the v1.2 things and once both ends support v1.3 that might be auto-negotiated. One can then set "force-tlsv12" but that is an administrative action [3] * Yet AFAIK this fine grained control [2] for TLSv1.3 only exists in >=1.8.15 [4] and Bionic is on haproxy 1.8.8. So any user of TLSv1.3 in Bionic haproxy would have to stay without that. There are further changes to TLS v1.3 handling enhancements [5] but also fixes [6] which aren't in 1.8.8 in Bionic. So one could say enabling this will enable an inferior TLSv1.3 and one might better not enable it, for an SRU the bar to not break old behavior is intentionally high - I tried to provide as much as possible background, the decision is up to the SRU team. [1]: https://cbonte.github.io/haproxy-dconv/1.8/configuration.html#3.1-ssl-default-bind-ciphers [2]: https://cbonte.github.io/haproxy-dconv/1.8/configuration.html#3.1-ssl-default-bind-ciphersuites [3]: https://www.haproxy.com/documentation/hapee/1-8r2/traffic-management/tls/#define-bind-directives-on-the-frontend [4]: https://github.com/haproxy/haproxy/blob/master/CHANGELOG#L2131 [5]: https://github.com/haproxy/haproxy/commit/526894ff3925d272c13e57926aa6b5d9d8ed5ee3 [6]: https://github.com/haproxy/haproxy/commit/bc34cd1de2ee80de63b5c4d319a501fc0d4ea2f5 [Other Info] * If this is nack'ed we will need an upload that prevents to enable TLSv1.3 to avoid enabling it by accident on e.g. a security update. --- haproxy needs to be rebuilt after #1797386 to take advantage of TLSv1.3. (If that's not desirable for some reason, then maybe TLSv1.3 should be actively disabled to avoid any surprises in case of a future bug fix release.) --- Output of haproxy -vv with stock package: Built with OpenSSL version : OpenSSL 1.1.0g 2 Nov 2017 Running on OpenSSL version : OpenSSL 1.1.1 11 Sep 2018 (VERSIONS DIFFER!) OpenSSL library supports TLS extensions : yes OpenSSL library supports SNI : yes OpenSSL library supports : TLSv1.0 TLSv1.1 TLSv1.2 --- Output after rebuilding the package from source: Built with OpenSSL version : OpenSSL 1.1.1 11 Sep 2018 Running on OpenSSL version : OpenSSL 1.1.1 11 Sep 2018 OpenSSL library supports TLS extensions : yes OpenSSL library supports SNI : yes OpenSSL library supports : TLSv1.0 TLSv1.1 TLSv1.2 TLSv1.3 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/haproxy/+bug/1841936/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-ha Post to : [email protected] Unsubscribe : https://launchpad.net/~ubuntu-ha More help : https://help.launchpad.net/ListHelp
