On 16/10/15 09:53, Matt Caswell via RT wrote: > > > On 13/10/15 12:31, Hubert Kario via RT wrote: >> On Tuesday 13 October 2015 09:22:53 Matt Caswell via RT wrote: >>> On 12/10/15 17:19, Matt Caswell via RT wrote: >>>> On 12/10/15 16:39, Matt Caswell via RT wrote: >>>>> The value of "in_read_app_data" not being true when it is supposed >>>>> to >>>>> appears to be running into a slightly different bug. It's also >>>>> present in 1.0.2 but you have to switch off version negotiation. >>>>> So running s_server like this in 1.0.2 and rerunning Hubert's test >>>>> will hit it: >>>>> >>>>> openssl s_server -www -tls1_2 >>>>> >>>>> The 1.0.2 version negotiation is hiding the issue. In master >>>>> version neg has been completely rewritten and simplified - but in >>>>> doing so no longer hides the problem. :-( >>>> >>>> Having done some more digging it seems the problem only occurs if >>>> you >>>> get the initial handshake, following by a second reneg handshake >>>> *and* interleaved app data all within the scope of a *single* >>>> SSL_read call. AFAICT if SSL_read returns between the first >>>> handshake and the second, you don't get the problem. >>> >>> Ok, updated version of the patch attached. This is for 1.0.2 but >>> should pass Hubert's tests even when you run s_server with "-tls1_2". >> >> yup, looks good with -tls1_2 now too >> >> for some reason my side can't negotiate TLS 1.1 or TLS 1.0 correctly so >> can't test -tls1_1 or -tls1 (I'm likely generating malformed CKE there, >> but need to check to be sure) > > I raised the ambiguity in the spec about when in the handshake > interleaved app data is allowed with the TLS WG. You can see the thread > here: > https://www.ietf.org/mail-archive/web/tls/current/threads.html#18017 > > I got a few responses, not all of which were consistent, and giving > different views. To summarise what I interpret as the main points: > > 1) Where a view was given it seemed to concur with the views expressed > here that the most sensible interpretation of the spec wording is that > interleaved app data is allowed up until the CCS, but not between CCS > and Finished. > 2) There was also a view expressed that, regardless of what the spec > says, allowing interleaved app data is *dangerous*! > 3) There seemed to be differing views on just how dangerous ranging from > it being "a highly dangerous idea" to "...there is a need for caution, > but in reality, it's not like you can use renegotiation to hand-off to > someone else entirely. The person you are talking to hasn't changed. > What is dangerous is making assertions about *new* things that the > renegotiation introduces", although the same person who made that last > observation also provided a list of very onerous mitigations that we > should put in place if were to do it (none of which are likely to be > adopted IMO without some form of official advice from the TLS WG). > > So now I really don't know what the "right" way forward is. Should we be > applying the patch or not?
I should add that another interesting point was that BoringSSL prohibits interleaved app data. Matt _______________________________________________ openssl-dev mailing list To unsubscribe: https://mta.openssl.org/mailman/listinfo/openssl-dev
