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From: "Randall S. Becker" <rsbecker@nexbridge.com>
To: "'Jeff King'" <peff@peff.net>, "'Daniel Carpenter'" <dc@ammonit.com>
Cc: "'Ævar Arnfjörð Bjarmason'" <avarab@gmail.com>, git@vger.kernel.org
Subject: RE: http.sslVersion only specifies minimum TLS version, later versions are allowed
Date: Mon, 3 May 2021 17:01:32 -0400	[thread overview]
Message-ID: <000c01d7405f$823fd090$86bf71b0$@nexbridge.com> (raw)
In-Reply-To: <YJBhH0eLKRSpPFy3@coredump.intra.peff.net>

On May 3, 2021 4:46 PM, Jeff King wrote:
>On Mon, May 03, 2021 at 03:02:10PM +0000, Daniel Carpenter wrote:
>
>> > Just looking at how the curl binary does it, "--tlsv1.2" means "1.2
>> > or greater" (which is not at all surprising; the library interface
>> > tends to mirror their command-line and vice versa, and our behavior
>> > is influenced by the library interface here).  But that implies to
>> > me that curl folks considered this and though the "or greater"
>> > behavior was useful (which makes sense -- the main goal is probably
>> > to avoid insecurities in older versions of the protocol).
>> >
>> > Anyway, the binary also has --tls-max for capping the maximum version.
>> > That seems more flexible in general than "use this version exactly"
>> > (if you only care that 1.3 is broken, then setting "max=1.2" lets
>> > you talk to servers that support 1.1 or 1.2).
>> >
>> > -Peff
>>
>> I agree that the current behaviour is better for most users, and that
>> some kind of separate "max" config option would work for anyone in my
>> situation.
>>
>> Another idea would be to keep the current behaviour for
>> `http.sslVersion`, but use an exact match with the environment
>> variable only. That already takes priority, and I imagine its main
>> appeal over the config option is for users that want to try something
>> with a specific TLS version.
>
>I think you're right that it may work for many people, but I'd shy away from it
>simply because it's subtle and hard to explain.
>
>Adding config and environment variables for "max" is pretty straight-forward to
>explain. I think it would also make sense to improve the documentation for
>http.sslVersion to make it clear that this is a minimum (the current wording is
>quite misleading).

What if http.sslVersion=v1[,v2]... were supported, so there would be an enumeration of allowed versions. The benefit of an enumeration is that you could force something like 3.0-fips if your environment requires a FIPS-certified version for communication. Admittedly this is a different use case than discussed above.

Just a thought.

Randall


  parent reply	other threads:[~2021-05-03 21:01 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-03 11:56 http.sslVersion only specifies minimum TLS version, later versions are allowed Daniel Carpenter
2021-05-03 13:55 ` Ævar Arnfjörð Bjarmason
2021-05-03 14:10   ` Jeff King
2021-05-03 15:02     ` Daniel Carpenter
2021-05-03 20:46       ` Jeff King
2021-05-03 20:56         ` Daniel Stenberg
2021-05-03 21:01         ` Randall S. Becker [this message]
2021-05-03 21:09           ` Daniel Stenberg
2021-05-03 21:23             ` Randall S. Becker

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