This bug was fixed in the package haproxy - 1.8.8-1ubuntu0.6
---------------
haproxy (1.8.8-1ubuntu0.6) bionic; urgency=medium
* Fix issues around dh_params when building against openssl 1.1.1
to avoid regressing the minimal key size (LP: 1841936)
- d/p/lp-1841936-BUG-MEDIUM-ssl-tune.ssl.default-dh-param-value-ignor.patch
- d/p/lp-1841936-CLEANUP-ssl-make-ssl_sock_load_dh_params-handle-errc.patch
haproxy (1.8.8-1ubuntu0.5) bionic; urgency=medium
* no change rebuild to pick up openssl 1.1.1 and via that
TLSv1.3 (LP: #1841936)
-- Christian Ehrhardt <christian.ehrha...@canonical.com> Wed, 23 Oct
2019 11:37:53 +0200
** Changed in: haproxy (Ubuntu Bionic)
Status: Fix Committed => Fix Released
--
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https://bugs.launchpad.net/bugs/1841936
Title:
Rebuild openssl 1.1.1 to pickup TLSv1.3 (bionic) and unbreak existing
builds against 1.1.1 (dh key size)
Status in HAProxy:
Fix Released
Status in haproxy package in Ubuntu:
Fix Committed
Status in haproxy source package in Bionic:
Fix Released
Status in haproxy source package in Disco:
Fix Released
Status in haproxy source package in Eoan:
Fix Released
Status in haproxy source package in Focal:
Fix Committed
Bug description:
[Impact-Bionic]
* 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.
[Impact Disco-Focal]
* openssl >=1.1.1 is in Disco-Focal already and thereby it was built
against that already. That made it pick up TLSv1.3, but also a related
bug that broke the ability to control the DHE key, it was always in
"ECDH auto" mode. Therefore the daemon didn't follow the config
anymore.
Upgraders would regress having their DH key behavior changed
unexpectedly.
[Test Case]
A)
* run "haproxy -vv" and check the reported TLS versions to include 1.3
B)
* download https://github.com/drwetter/testssl.sh
* Install haproxy
* ./testssl.sh --pfs <localip>:443
* Check the reported DH key/group (shoudl stay 1024)
* Check if settings work to bump it like
tune.ssl.default-dh-param 2048
into
/etc/haproxy/haproxy.cfg
[Regression Potential-Bionic]
* 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.
[Regression Potential-Disco-Focal]
* The fixes let the admin regain control of the DH key configuration
which is the fix. But remember that the default config didn't specify
any. Therefore we have two scenarios:
a) an admin had set custom DH parameters which were ignored. He had no
chance to control them and needs the fix. He might have been under
the impression that his keys are safe (there is a CVE against small
ones) and only now is he really safe -> gain high, regression low
b) an admin had not set anything, the default config is meant to use
(compatibility) and the program reported "I'm using 1024, but you
should set it higher". But what really happened was ECDH auto mode
which has longer keys and different settings. Those systems will
be "fixed" by finally following the config, but that means the key
will "now" after the fix be vulnerable.
-> for their POV a formerly secure setup will become vulnerable
I'd expect that any professional setup would use explicit config as it
has seen the warning since day #1 and also any kind of deployment
recipes should use big keys. So the majority of users should be in (a).
c) And OTOH there are people like the reporter who strictly NEED the
key to be small for their devices they have to support. They will
finally be able to use the small keys again which formerly was
impossible.
Summary: (a) good (c) good, (b) good, but a regression in some POV
[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
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