PR: 1574

Submitted by: Jouni Malinen <j@w1.fi>
Approved by: steve@openssl.org

Ticket override support for EAP-FAST.

CHANGES

@@ -4,6 +4,9 @@
 
  Changes between 0.9.8j and 0.9.9  [xx XXX xxxx]
 
+  *) Add session ticket override functionality for use by EAP-FAST.
+     [Jouni Malinen <j@w1.fi>]
+
   *) Modify HMAC functions to return a value. Since these can be implemented
      in an ENGINE errors can occur.
      [Steve Henson]

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
+	/* If we have no ticket it cannot be a resumed session. */
-	 * a non-zero session length would never reach here) it cannot be a
+	if (!s->session->tlsext_tick)
-	 * resumed session.
-	 */
-	if (!s->session->tlsext_tick || s->session->session_id_length)
 		return 1;
 	/* this function is called when we really expect a Certificate
 	 * message, so permit appropriate message length */

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]);
 

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(void);
 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

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}
 	};
 

ssl/ssl_sess.c

@@ -834,6 +834,61 @@ long SSL_CTX_get_timeout(const SSL_CTX *s)
 	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;

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_tlsext(SSL *s, unsigned char *p, unsigned cha
 		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_tlsext(SSL *s, unsigned char *p, unsigned cha
 			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, unsigned char **p, unsigned char *d, in
 				}
 			}
 #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, unsigned char **p, unsigned char *d, in
 
 		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 char *session_id, int len,
 				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);
 			}

ssl/tls1.h

@@ -512,6 +512,13 @@ SSL_CTX_callback_ctrl(ssl,SSL_CTRL_SET_TLSEXT_TICKET_KEY_CB,(void (*)(void))cb)
 #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

util/ssleay.num

@@ -254,3 +254,5 @@ PEM_read_bio_SSL_SESSION                302	EXIST::FUNCTION:
 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