Re: Attack research on HTTP/2 implementations

On Thu, Aug 05, 2021 at 10:10:21PM -0700, Nick Harper wrote:
> On Thu, Aug 5, 2021 at 9:57 PM Willy Tarreau <w@1wt.eu> wrote:
> 
> > On Thu, Aug 05, 2021 at 09:01:33PM -0700, Nick Harper wrote:
> > > I see that draft-ietf-httpbis-http2bis-03 has new
> > > language to mostly cover that issue. I say "mostly" because I don't see
> > any
> > > specification of what should happen if multiple :authority pseudo-headers
> > > are present. (I would argue that that is a malformed request.)
> >
> > Yep it's malformed. In 7540#8.1.2.3, it was already said:
> >
> >    All HTTP/2 requests MUST include exactly one valid value for the
> >    ":method", ":scheme", and ":path" pseudo-header fields, ...
> >
> 
> Unless I'm misreading something, that only covers some pseudo-headers, but
> it doesn't include :authority. (The same language missing :authority is in
> http2bis section 8.3.1.)

Indeed, you're absolutely right, I never noticed that. This perfectly
illustrates what I mentioned regarding detailed enumeration versus
intent. I summarized that by making sure no pseudo-header could appear
more than once (and of course making sure all those above are present)
but I made my implementation resistant against this by pure accident :-/

Willy

Received on Friday, 6 August 2021 06:57:10 UTC