We've found a way to recreate the scenario using s_client/s_server. We're
using the -no_ticket option on the server. Therefore, the ServerHello doesn't
contain the session ticket extension. It also doesn't send the
NewSessionTicket message.
To summarize the problem, when the client side is using
SSL_set_session_secret_cb() and including a valid ticket in the ClintHello,
then the logic in ssl3_get_server_hello() assumes the server is doing session
resumption. This puts the client-side state machine into the
SSL3_ST_CR_FINISHED_A. However, since the server side is configured to not do
resumption via the -no_ticket option, the server continues with a normal
handshake by sending the Certificate message. The client aborts the handshake
when it receives the Certificate message while in the SSL3_ST_CR_FINISHED_A
state.
As Erik identified earlier in the thread, the cause of this appears to be the
addition of setting s->hit in the following code:
if (s->version >= TLS1_VERSION && s->tls_session_secret_cb) {
SSL_CIPHER *pref_cipher = NULL;
s->session->master_key_length = sizeof(s->session->master_key);
if (s->tls_session_secret_cb(s, s->session->master_key,
&s->session->master_key_length,
NULL, &pref_cipher,
s->tls_session_secret_cb_arg)) {
s->session->cipher = pref_cipher ?
pref_cipher : ssl_get_cipher_by_char(s, p + j);
s->hit = 1;
}
}
Why does the client-side now assume the server is doing session resumption
simply because the session secret callback facility is being used?
________________________________________
From: openssl-dev [[email protected]] on behalf of Dr. Stephen
Henson [[email protected]]
Sent: Thursday, March 19, 2015 11:49 AM
To: [email protected]
Subject: Re: [openssl-dev] s3_clnt.c changes regarding external pre-shared
secret seem to break EAP-FAST
On Thu, Mar 19, 2015, Erik Tkal wrote:
>
> If I do not send a sessionID in the clientHello but do send a valid
> sessionTicket extension, the server goes straight to changeCipherSpec and
> the client generates an UnexpectedMessage alert.
>
Does the server send back an empty session ticket extension?
Steve.
--
Dr Stephen N. Henson. OpenSSL project core developer.
Commercial tech support now available see: http://www.openssl.org
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