On Wed, Nov 12, 2008 at 07:07:56PM +0100, Stephen Henson via RT wrote:
> Well I'm assuming that there needs to be a way to obtain the ticket
> value the peer has sent. Although it is possible to use the debugging
> interface for that it then prevents it being used for anything else.
>
> Something like an SSL_set_session_ticket_cb() function which would call
> the supplied callback with the received ticket extension value.
The attached version adds SSL_set_session_ticket_ext_cb() to register a
callback that will be called whenever a Session Ticket extension is
received in ServerHello or ClientHello. EAP-FAST will only use this from
the ClientHello, but I added the same code for ServerHello should anyone
else have need for that in a client.
I also removed the extra SSL_set_hello_extension() wrapper to clean up
the patch. I have run a quick test with this version and
hostapd/wpa_supplicant, but I haven't committed the matching changes yet
into my repository since I did not want to change the API use there
before the modified version gets into the OpenSSL repository.
--
Jouni Malinen PGP id EFC895FA
This patch adds support for TLS SessionTicket extension (RFC 5077) for
the parts used by EAP-FAST (RFC 4851).
This is based on the patch from Alexey Kobozev <[EMAIL PROTECTED]>
(sent to openssl-dev mailing list on Tue, 07 Jun 2005 15:40:58 +0300).
Index: openssl-SNAP-20081111/ssl/s3_clnt.c
===================================================================
--- openssl-SNAP-20081111.orig/ssl/s3_clnt.c
+++ openssl-SNAP-20081111/ssl/s3_clnt.c
@@ -788,6 +788,23 @@ int ssl3_get_server_hello(SSL *s)
goto f_err;
}
+#ifndef OPENSSL_NO_TLSEXT
+ /* check if we want to resume the session based on external pre-shared
secret */
+ 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);
+ }
+ }
+#endif /* OPENSSL_NO_TLSEXT */
+
if (j != 0 && j == s->session->session_id_length
&& memcmp(p,s->session->session_id,j) == 0)
{
@@ -2927,11 +2944,8 @@ static int ssl3_check_finished(SSL *s)
{
int ok;
long n;
- /* If we have no ticket or session ID is non-zero length (a match of
- * a non-zero session length would never reach here) it cannot be a
- * resumed session.
- */
- if (!s->session->tlsext_tick || s->session->session_id_length)
+ /* If we have no ticket it cannot be a resumed session. */
+ if (!s->session->tlsext_tick)
return 1;
/* this function is called when we really expect a Certificate
* message, so permit appropriate message length */
Index: openssl-SNAP-20081111/ssl/s3_srvr.c
===================================================================
--- openssl-SNAP-20081111.orig/ssl/s3_srvr.c
+++ openssl-SNAP-20081111/ssl/s3_srvr.c
@@ -1010,6 +1010,59 @@ int ssl3_get_client_hello(SSL *s)
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO,SSL_R_CLIENTHELLO_TLSEXT);
goto err;
}
+
+ /* Check if we want to use external pre-shared secret for this
+ * handshake for not reused session only. We need to generate
+ * server_random before calling tls_session_secret_cb in order to allow
+ * SessionTicket processing to use it in key derivation. */
+ {
+ unsigned long Time;
+ unsigned char *pos;
+ Time=(unsigned long)time(NULL); /* Time */
+ pos=s->s3->server_random;
+ l2n(Time,pos);
+ if (RAND_pseudo_bytes(pos,SSL3_RANDOM_SIZE-4) <= 0)
+ {
+ al=SSL_AD_INTERNAL_ERROR;
+ goto f_err;
+ }
+ }
+
+ if (!s->hit && 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,
+ ciphers, &pref_cipher, s->tls_session_secret_cb_arg))
+ {
+ s->hit=1;
+ s->session->ciphers=ciphers;
+ s->session->verify_result=X509_V_OK;
+
+ ciphers=NULL;
+
+ /* check if some cipher was preferred by call back */
+ pref_cipher=pref_cipher ? pref_cipher :
ssl3_choose_cipher(s, s->session->ciphers, SSL_get_ciphers(s));
+ if (pref_cipher == NULL)
+ {
+ al=SSL_AD_HANDSHAKE_FAILURE;
+
SSLerr(SSL_F_SSL3_GET_CLIENT_HELLO,SSL_R_NO_SHARED_CIPHER);
+ goto f_err;
+ }
+
+ s->session->cipher=pref_cipher;
+
+ if (s->cipher_list)
+ sk_SSL_CIPHER_free(s->cipher_list);
+
+ if (s->cipher_list_by_id)
+ sk_SSL_CIPHER_free(s->cipher_list_by_id);
+
+ s->cipher_list = sk_SSL_CIPHER_dup(s->session->ciphers);
+ s->cipher_list_by_id =
sk_SSL_CIPHER_dup(s->session->ciphers);
+ }
+ }
#endif
/* Worst case, we will use the NULL compression, but if we have other
@@ -1134,16 +1187,22 @@ int ssl3_send_server_hello(SSL *s)
unsigned char *buf;
unsigned char *p,*d;
int i,sl;
- unsigned long l,Time;
+ unsigned long l;
+#ifdef OPENSSL_NO_TLSEXT
+ unsigned long Time;
+#endif
if (s->state == SSL3_ST_SW_SRVR_HELLO_A)
{
buf=(unsigned char *)s->init_buf->data;
+#ifdef OPENSSL_NO_TLSEXT
p=s->s3->server_random;
+ /* Generate server_random if it was not needed previously */
Time=(unsigned long)time(NULL); /* Time */
l2n(Time,p);
if (RAND_pseudo_bytes(p,SSL3_RANDOM_SIZE-4) <= 0)
return -1;
+#endif
/* Do the message type and length last */
d=p= &(buf[4]);
Index: openssl-SNAP-20081111/ssl/ssl_err.c
===================================================================
--- openssl-SNAP-20081111.orig/ssl/ssl_err.c
+++ openssl-SNAP-20081111/ssl/ssl_err.c
@@ -263,6 +263,7 @@ static ERR_STRING_DATA SSL_str_functs[]=
{ERR_FUNC(SSL_F_TLS1_PRF), "tls1_prf"},
{ERR_FUNC(SSL_F_TLS1_SETUP_KEY_BLOCK), "TLS1_SETUP_KEY_BLOCK"},
{ERR_FUNC(SSL_F_WRITE_PENDING), "WRITE_PENDING"},
+{ERR_FUNC(SSL_F_SSL_SET_SESSION_TICKET_EXT), "SSL_set_session_ticket_ext"},
{0,NULL}
};
Index: openssl-SNAP-20081111/ssl/ssl.h
===================================================================
--- openssl-SNAP-20081111.orig/ssl/ssl.h
+++ openssl-SNAP-20081111/ssl/ssl.h
@@ -355,6 +355,7 @@ extern "C" {
* 'struct ssl_st *' function parameters used to prototype callbacks
* in SSL_CTX. */
typedef struct ssl_st *ssl_crock_st;
+typedef struct tls_session_ticket_ext_st TLS_SESSION_TICKET_EXT;
/* used to hold info on the particular ciphers used */
typedef struct ssl_cipher_st
@@ -378,6 +379,9 @@ typedef struct ssl_cipher_st
DECLARE_STACK_OF(SSL_CIPHER)
+typedef int (*tls_session_ticket_ext_cb_fn)(SSL *s, const unsigned char *data,
int len, void *arg);
+typedef int (*tls_session_secret_cb_fn)(SSL *s, void *secret, int *secret_len,
STACK_OF(SSL_CIPHER) *peer_ciphers, SSL_CIPHER **cipher, void *arg);
+
/* Used to hold functions for SSLv2 or SSLv3/TLSv1 functions */
typedef struct ssl_method_st
{
@@ -1145,6 +1149,17 @@ struct ssl_st
void *tlsext_opaque_prf_input;
size_t tlsext_opaque_prf_input_len;
+ /* TLS Session Ticket extension override */
+ TLS_SESSION_TICKET_EXT *tlsext_session_ticket;
+
+ /* TLS Session Ticket extension callback */
+ tls_session_ticket_ext_cb_fn tls_session_ticket_ext_cb;
+ void *tls_session_ticket_ext_cb_arg;
+
+ /* TLS pre-shared secret session resumption */
+ tls_session_secret_cb_fn tls_session_secret_cb;
+ void *tls_session_secret_cb_arg;
+
SSL_CTX * initial_ctx; /* initial ctx, used to store sessions */
#define session_ctx initial_ctx
#else
@@ -1746,6 +1761,15 @@ void *SSL_COMP_get_compression_methods(v
int SSL_COMP_add_compression_method(int id,void *cm);
#endif
+/* TLS extensions functions */
+int SSL_set_session_ticket_ext(SSL *s, void *ext_data, int ext_len);
+
+int SSL_set_session_ticket_ext_cb(SSL *s, tls_session_ticket_ext_cb_fn cb,
+ void *arg);
+
+/* Pre-shared secret session resumption functions */
+int SSL_set_session_secret_cb(SSL *s, tls_session_secret_cb_fn
tls_session_secret_cb, void *arg);
+
/* BEGIN ERROR CODES */
/* The following lines are auto generated by the script mkerr.pl. Any changes
* made after this point may be overwritten when the script is next run.
@@ -1948,6 +1972,7 @@ void ERR_load_SSL_strings(void);
#define SSL_F_TLS1_PRF 284
#define SSL_F_TLS1_SETUP_KEY_BLOCK 211
#define SSL_F_WRITE_PENDING 212
+#define SSL_F_SSL_SET_SESSION_TICKET_EXT 213
/* Reason codes. */
#define SSL_R_APP_DATA_IN_HANDSHAKE 100
Index: openssl-SNAP-20081111/ssl/ssl_sess.c
===================================================================
--- openssl-SNAP-20081111.orig/ssl/ssl_sess.c
+++ openssl-SNAP-20081111/ssl/ssl_sess.c
@@ -834,6 +834,61 @@ long SSL_CTX_get_timeout(const SSL_CTX *
return(s->session_timeout);
}
+#ifndef OPENSSL_NO_TLSEXT
+int SSL_set_session_secret_cb(SSL *s, int (*tls_session_secret_cb)(SSL *s,
void *secret, int *secret_len,
+ STACK_OF(SSL_CIPHER) *peer_ciphers, SSL_CIPHER **cipher, void *arg),
void *arg)
+ {
+ if (s == NULL) return(0);
+ s->tls_session_secret_cb = tls_session_secret_cb;
+ s->tls_session_secret_cb_arg = arg;
+ return(1);
+ }
+
+int SSL_set_session_ticket_ext_cb(SSL *s, tls_session_ticket_ext_cb_fn cb,
+ void *arg)
+ {
+ if (s == NULL) return(0);
+ s->tls_session_ticket_ext_cb = cb;
+ s->tls_session_ticket_ext_cb_arg = arg;
+ return(1);
+ }
+
+int SSL_set_session_ticket_ext(SSL *s, void *ext_data, int ext_len)
+ {
+ if (s->version >= TLS1_VERSION)
+ {
+ if (s->tlsext_session_ticket)
+ {
+ OPENSSL_free(s->tlsext_session_ticket);
+ s->tlsext_session_ticket = NULL;
+ }
+
+ s->tlsext_session_ticket =
OPENSSL_malloc(sizeof(TLS_SESSION_TICKET_EXT) + ext_len);
+ if (!s->tlsext_session_ticket)
+ {
+ SSLerr(SSL_F_SSL_SET_SESSION_TICKET_EXT,
ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+
+ if (ext_data)
+ {
+ s->tlsext_session_ticket->length = ext_len;
+ s->tlsext_session_ticket->data =
s->tlsext_session_ticket + 1;
+ memcpy(s->tlsext_session_ticket->data, ext_data,
ext_len);
+ }
+ else
+ {
+ s->tlsext_session_ticket->length = 0;
+ s->tlsext_session_ticket->data = NULL;
+ }
+
+ return 1;
+ }
+
+ return 0;
+ }
+#endif /* OPENSSL_NO_TLSEXT */
+
typedef struct timeout_param_st
{
SSL_CTX *ctx;
Index: openssl-SNAP-20081111/ssl/t1_lib.c
===================================================================
--- openssl-SNAP-20081111.orig/ssl/t1_lib.c
+++ openssl-SNAP-20081111/ssl/t1_lib.c
@@ -154,6 +154,12 @@ int tls1_new(SSL *s)
void tls1_free(SSL *s)
{
+#ifndef OPENSSL_NO_TLSEXT
+ if (s->tlsext_session_ticket)
+ {
+ OPENSSL_free(s->tlsext_session_ticket);
+ }
+#endif /* OPENSSL_NO_TLSEXT */
ssl3_free(s);
}
@@ -357,8 +363,23 @@ unsigned char *ssl_add_clienthello_tlsex
int ticklen;
if (s->session && s->session->tlsext_tick)
ticklen = s->session->tlsext_ticklen;
+ else if (s->session && s->tlsext_session_ticket &&
+ s->tlsext_session_ticket->data)
+ {
+ ticklen = s->tlsext_session_ticket->length;
+ s->session->tlsext_tick = OPENSSL_malloc(ticklen);
+ if (!s->session->tlsext_tick)
+ return NULL;
+ memcpy(s->session->tlsext_tick,
+ s->tlsext_session_ticket->data,
+ ticklen);
+ s->session->tlsext_ticklen = ticklen;
+ }
else
ticklen = 0;
+ if (ticklen == 0 && s->tlsext_session_ticket &&
+ s->tlsext_session_ticket->data == NULL)
+ goto skip_ext;
/* Check for enough room 2 for extension type, 2 for len
* rest for ticket
*/
@@ -371,6 +392,7 @@ unsigned char *ssl_add_clienthello_tlsex
ret += ticklen;
}
}
+ skip_ext:
#ifdef TLSEXT_TYPE_opaque_prf_input
if (s->s3->client_opaque_prf_input != NULL)
@@ -751,6 +773,15 @@ int ssl_parse_clienthello_tlsext(SSL *s,
}
}
#endif
+ else if (type == TLSEXT_TYPE_session_ticket)
+ {
+ if (s->tls_session_ticket_ext_cb &&
+ !s->tls_session_ticket_ext_cb(s, data, size,
s->tls_session_ticket_ext_cb_arg))
+ {
+ *al = TLS1_AD_INTERNAL_ERROR;
+ return 0;
+ }
+ }
else if (type == TLSEXT_TYPE_status_request
&& s->ctx->tlsext_status_cb)
{
@@ -928,6 +959,12 @@ int ssl_parse_serverhello_tlsext(SSL *s,
else if (type == TLSEXT_TYPE_session_ticket)
{
+ if (s->tls_session_ticket_ext_cb &&
+ !s->tls_session_ticket_ext_cb(s, data, size,
s->tls_session_ticket_ext_cb_arg))
+ {
+ *al = TLS1_AD_INTERNAL_ERROR;
+ return 0;
+ }
if ((SSL_get_options(s) & SSL_OP_NO_TICKET)
|| (size > 0))
{
@@ -1435,6 +1472,15 @@ int tls1_process_ticket(SSL *s, unsigned
s->tlsext_ticket_expected = 1;
return 0; /* Cache miss */
}
+ if (s->tls_session_secret_cb)
+ {
+ /* Indicate cache miss here and instead of
+ * generating the session from ticket now,
+ * trigger abbreviated handshake based on
+ * external mechanism to calculate the master
+ * secret later. */
+ return 0;
+ }
return tls_decrypt_ticket(s, p, size, session_id, len,
ret);
}
Index: openssl-SNAP-20081111/ssl/tls1.h
===================================================================
--- openssl-SNAP-20081111.orig/ssl/tls1.h
+++ openssl-SNAP-20081111/ssl/tls1.h
@@ -512,6 +512,13 @@ SSL_CTX_callback_ctrl(ssl,SSL_CTRL_SET_T
#define TLS_MD_MASTER_SECRET_CONST
"\x6d\x61\x73\x74\x65\x72\x20\x73\x65\x63\x72\x65\x74" /*master secret*/
#endif
+/* TLS Session Ticket extension struct */
+struct tls_session_ticket_ext_st
+ {
+ unsigned short length;
+ void *data;
+ };
+
#ifdef __cplusplus
}
#endif
Index: openssl-SNAP-20081111/util/ssleay.num
===================================================================
--- openssl-SNAP-20081111.orig/util/ssleay.num
+++ openssl-SNAP-20081111/util/ssleay.num
@@ -254,3 +254,5 @@ PEM_read_bio_SSL_SESSION
SSL_CTX_set_psk_server_callback 303 EXIST::FUNCTION:PSK
SSL_get_psk_identity 304 EXIST::FUNCTION:PSK
PEM_write_SSL_SESSION 305 EXIST:!WIN16:FUNCTION:
+SSL_set_session_ticket_ext 306 EXIST::FUNCTION:TLSEXT
+SSL_set_session_secret_cb 307 EXIST::FUNCTION:TLSEXT
