Re: [TLS] Narrowing allowed characters in ALPN ?

Viktor Dukhovni <ietf-dane@dukhovni.org> Thu, 20 May 2021 15:28 UTC

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Date: Thu, 20 May 2021 11:28:27 -0400
From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Subject: Re: [TLS] Narrowing allowed characters in ALPN ?
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On Thu, May 20, 2021 at 11:23:15AM -0400, David Benjamin wrote:

> SVCB's syntax would need us to not only exclude non-ASCII characters but
> also avoid random delimiters like commas, right? I think that's going a bit
> too far. As Ryan notes, complex definitions for allowed strings result in
> ambiguities around who is responsible for validating what and subtle
> variations in different implementations. That ambiguity can lead to
> injection attacks when one component of a system expects some validation,
> but the other component disagrees.

Just the registry needs to be restricted.  TLS implementations would
support all possible inputs.  HTTPS/SVCB would no longer need to parse
complex quoted input formats.

-- 
    Viktor.