relates to SSL_CTX flags and the use of "external" session caching. The
existing flag, "SSL_SESS_CACHE_NO_INTERNAL_LOOKUP" remains but is
supplemented with a complimentary flag, "SSL_SESS_CACHE_NO_INTERNAL_STORE".
The bitwise OR of the two flags is also defined as
"SSL_SESS_CACHE_NO_INTERNAL" and is the flag that should be used by most
applications wanting to implement session caching *entirely* by its own
provided callbacks. As the documented behaviour contradicted actual
behaviour up until recently, and since that point behaviour has itself been
inconsistent anyway, this change should not introduce any compatibility
problems. I've adjusted the relevant documentation to elaborate about how
this works.
Kudos to "Nadav Har'El" <nyh@math.technion.ac.il> for diagnosing these
anomalies and testing this patch for correctness.
PR: 311
Changes marked "(CHATS)" were sponsored by the Defense Advanced
Research Projects Agency (DARPA) and Air Force Research Laboratory,
Air Force Materiel Command, USAF, under agreement number
F30602-01-2-0537.
New macros SSL[_CTX]_set_msg_callback_arg().
Message callback imlementation for SSL 3.0/TLS 1.0 (no SSL 2.0 yet).
New '-msg' option for 'openssl s_client' and 'openssl s_server'
that enable a message callback that displays all protocol messages.
In ssl3_get_client_hello (ssl/s3_srvr.c), generate a fatal alert if
client_version is smaller than the protocol version in use.
Also change ssl23_get_client_hello (ssl/s23_srvr.c) to select TLS 1.0
if the client demanded SSL 3.0 but only TLS 1.0 is enabled; then the
client will at least see that alert.
Fix SSL[_CTX]_ctrl prototype (void * instead of char * for generic
pointer).
Add/update some OpenSSL copyright notices.
Both have per-SSL_CTX defaults.
These new values can be set by calling SSL[_CTX]_[callback_]ctrl
with codes SSL_CTRL_SET_MSG_CALLBACK and SSL_CTRL_SET_MSG_CALLBACK_ARG.
So far, the callback is never actually called.
Also rearrange some SSL_CTX struct members (some exist just in
SSL_CTXs, others are defaults for SSLs and are either copied
during SSL_new, or used if the value in the SSL is not set;
these three classes of members were not in a logical order),
and add some missing assignments to SSL_dup.
'Handshake' protocol structures are kept in memory, including
'msg_type' and 'length'.
(This is in preparation of future support for callbacks that get to
peek at handshake messages and the like.)
reveal whether illegal block cipher padding was found or a MAC
verification error occured.
In ssl/s2_pkt.c, verify that the purported number of padding bytes is in
the legal range.
His comments are:
First, it corrects a problem introduced in the last patch where the
kssl_map_enc() would intentionally return NULL for valid ENCTYPE
values. This was done to prevent verification of the kerberos 5
authenticator from being performed when Derived Key ciphers were
in use. Unfortunately, the authenticator verification routine was
not the only place that function was used. And it caused core dumps.
Second, it attempt to add to SSL_SESSION the Kerberos 5 Client
Principal Name.
SSL according to RFC 2712. His comment is:
This is a patch to openssl-SNAP-20010702 to support Kerberized SSL
authentication. I'm expecting to have the full kssl-0.5 kit up on
sourceforge by the end of the week. The full kit includes patches
for mod-ssl, apache, and a few text clients. The sourceforge URL
is http://sourceforge.net/projects/kssl/ .
Thanks to a note from Simon Wilkinson I've replaced my KRB5 AP_REQ
message with a real KerberosWrapper struct. I think this is fully
RFC 2712 compliant now, including support for the optional
authenticator field. I also added openssl-style ASN.1 macros for
a few Kerberos structs; see crypto/krb5/ if you're interested.
an SSL_CTX's session cache, it is necessary to compare the ssl_version at
the same time (a conflict is defined, courtesy of SSL_SESSION_cmp(), as a
matching id/id_length pair and a matching ssl_version). However, the
SSL_SESSION that will result from the current negotiation does not
necessarily have the same ssl version as the "SSL_METHOD" in use by the
SSL_CTX - part of the work in a handshake is to agree on an ssl version!
This is fixed by having the check function accept an SSL pointer rather
than the SSL_CTX it belongs to.
[Thanks to Lutz for illuminating the full extent of my stupidity]
SSL/TLS session IDs in a server. According to RFC2246, the session ID is an
arbitrary value chosen by the server. It can be useful to have some control
over this "arbitrary value" so as to choose it in ways that can aid in
things like external session caching and balancing (eg. clustering). The
default session ID generation is to fill the ID with random data.
The callback used by default is built in to ssl_sess.c, but registering a
callback in an SSL_CTX or in a particular SSL overrides this. BTW: SSL
callbacks will override SSL_CTX callbacks, and a new SSL structure inherits
any callback set in its 'parent' SSL_CTX. The header comments describe how
this mechanism ticks, and source code comments describe (hopefully) why it
ticks the way it does.
Man pages are on the way ...
[NB: Lutz was also hacking away and helping me to figure out how best to do
this.]
