Commit 9bdedec0 authored by Emilia Kasper's avatar Emilia Kasper
Browse files

Tighten session ticket handling 



Tighten client-side session ticket handling during renegotiation:
ensure that the client only accepts a session ticket if the server sends
the extension anew in the ServerHello. Previously, a TLS client would
reuse the old extension state and thus accept a session ticket if one was
announced in the initial ServerHello.

Reviewed-by: default avatarBodo Moeller <bodo@openssl.org>
(cherry picked from commit d663df23)

Conflicts:
	CHANGES
parent f63fa8b1

CHANGES

+6 −1
Original line number Diff line number Diff line
@@ -4,7 +4,12 @@ 


 Changes between 1.0.1j and 1.0.1k [xx XXX xxxx]



  *)

  *) Tighten client-side session ticket handling during renegotiation:

     ensure that the client only accepts a session ticket if the server sends

     the extension anew in the ServerHello. Previously, a TLS client would

     reuse the old extension state and thus accept a session ticket if one was

     announced in the initial ServerHello.

     [Emilia Käsper]



 Changes between 1.0.1i and 1.0.1j [15 Oct 2014]

ssl/s3_clnt.c

+9 −1
Original line number Diff line number Diff line
@@ -225,6 +225,14 @@ int ssl3_connect(SSL *s) 
			s->renegotiate=1;

			s->state=SSL_ST_CONNECT;

			s->ctx->stats.sess_connect_renegotiate++;

#ifndef OPENSSL_NO_TLSEXT

			/*

			 * If renegotiating, the server may choose to not issue

			 * a new ticket, so reset the flag. It will be set to

			 * the right value when parsing ServerHello extensions.

			 */

			s->tlsext_ticket_expected = 0;

#endif

			/* break */

		case SSL_ST_BEFORE:

		case SSL_ST_CONNECT:
@@ -2223,7 +2231,7 @@ int ssl3_get_new_session_ticket(SSL *s) 
		}

	memcpy(s->session->tlsext_tick, p, ticklen);

	s->session->tlsext_ticklen = ticklen;

	/* There are two ways to detect a resumed ticket sesion.

	/* There are two ways to detect a resumed ticket session.

	 * One is to set an appropriate session ID and then the server

	 * must return a match in ServerHello. This allows the normal

	 * client session ID matching to work and we know much

ssl/ssl_sess.c

+15 −1
Original line number Diff line number Diff line
@@ -335,7 +335,21 @@ int ssl_get_new_session(SSL *s, int session) 
			return(0);

			}

#ifndef OPENSSL_NO_TLSEXT

		/* If RFC4507 ticket use empty session ID */

		/*

		 * If RFC5077 ticket, use empty session ID (as server).

		 * Note that:

		 * (a) ssl_get_prev_session() does lookahead into the

		 *     ClientHello extensions to find the session ticket.

		 *     When ssl_get_prev_session() fails, s3_srvr.c calls

		 *     ssl_get_new_session() in ssl3_get_client_hello().

		 *     At that point, it has not yet parsed the extensions,

		 *     however, because of the lookahead, it already knows

		 *     whether a ticket is expected or not.

		 *

		 * (b) s3_clnt.c calls ssl_get_new_session() before parsing

		 *     ServerHello extensions, and before recording the session

		 *     ID received from the server, so this block is a noop.

		 */

		if (s->tlsext_ticket_expected)

			{

			ss->session_id_length = 0;