Re: SCRAM with channel binding downgrade attack

On Fri, May 18, 2018 at 12:03:49PM +0900, Michael Paquier wrote:
> On Fri, May 18, 2018 at 10:46:46AM +0900, Michael Paquier wrote:
> > From a security point of view, 1) is important for libpq, but I am not
> > much enthusiast about 2) as a whole. The backend has proper support for
> > channel binding, hence other drivers speaking the protocol could have
> > their own restriction mechanisms.
>
> So, I have been playing with libpq to address point 1), and added a new
> connection parameter called channel_binding_mode which can be set to
> 'prefer', which is what libpq uses now, and 'require'. The patch has
> two important parts:

Good work, but I think the existance of both scram_channel_binding and
channel_binding_mode in libpq is confusing. I am thinking we should
have one channel binding parameter that can take values "prefer",
"tls-unique", "tls-server-end-point", and "require". I don't see the
point to having "none" and "allow" that sslmode supports. "tls-unique"
and "tls-server-end-point" would _require_ those channel binding modes;
the setting would never be ignored, e.g. if no SSL.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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