Fix some style issues identified during review
[openssl.git] / ssl / statem / statem_clnt.c
index 3129456ce7aedc3dfc799fd57d60005c5b7f0140..ec1a1de5dae9c8a89c647b2c3c95d31e142129ba 100644 (file)
@@ -106,21 +106,107 @@ static int key_exchange_expected(SSL *s)
     return 0;
 }
 
+/*
+ * ossl_statem_client_read_transition() encapsulates the logic for the allowed
+ * handshake state transitions when a TLS1.3 client is reading messages from the
+ * server. The message type that the server has sent is provided in |mt|. The
+ * current state is in |s->statem.hand_state|.
+ *
+ * Return values are 1 for success (transition allowed) and  0 on error
+ * (transition not allowed)
+ */
+static int ossl_statem_client13_read_transition(SSL *s, int mt)
+{
+    OSSL_STATEM *st = &s->statem;
+
+    /*
+     * TODO(TLS1.3): This is still based on the TLSv1.2 state machine. Over time
+     * we will update this to look more like real TLSv1.3
+     */
+
+    /*
+     * Note: There is no case for TLS_ST_CW_CLNT_HELLO, because we haven't
+     * yet negotiated TLSv1.3 at that point so that is handled by
+     * ossl_statem_client_read_transition()
+     */
+
+    switch (st->hand_state) {
+    default:
+        break;
+
+    case TLS_ST_CR_SRVR_HELLO:
+        if (s->hit) {
+            if (mt == SSL3_MT_FINISHED) {
+                st->hand_state = TLS_ST_CR_FINISHED;
+                return 1;
+            }
+        } else {
+            if (mt == SSL3_MT_CERTIFICATE_REQUEST) {
+                st->hand_state = TLS_ST_CR_CERT_REQ;
+                return 1;
+            }
+            if (mt == SSL3_MT_CERTIFICATE) {
+                st->hand_state = TLS_ST_CR_CERT;
+                return 1;
+            }
+        }
+        break;
+
+    case TLS_ST_CR_CERT_REQ:
+        if (mt == SSL3_MT_CERTIFICATE) {
+            st->hand_state = TLS_ST_CR_CERT;
+            return 1;
+        }
+        break;
+
+    case TLS_ST_CR_CERT:
+        /*
+         * The CertificateStatus message is optional even if
+         * |tlsext_status_expected| is set
+         */
+        if (s->tlsext_status_expected && mt == SSL3_MT_CERTIFICATE_STATUS) {
+            st->hand_state = TLS_ST_CR_CERT_STATUS;
+            return 1;
+        }
+        /* Fall through */
+
+    case TLS_ST_CR_CERT_STATUS:
+        if (mt == SSL3_MT_FINISHED) {
+            st->hand_state = TLS_ST_CR_FINISHED;
+            return 1;
+        }
+        break;
+
+    }
+
+    /* No valid transition found */
+    return 0;
+}
+
 /*
  * ossl_statem_client_read_transition() encapsulates the logic for the allowed
  * handshake state transitions when the client is reading messages from the
  * server. The message type that the server has sent is provided in |mt|. The
  * current state is in |s->statem.hand_state|.
  *
- *  Return values are:
- *  1: Success (transition allowed)
- *  0: Error (transition not allowed)
+ * Return values are 1 for success (transition allowed) and  0 on error
+ * (transition not allowed)
  */
 int ossl_statem_client_read_transition(SSL *s, int mt)
 {
     OSSL_STATEM *st = &s->statem;
     int ske_expected;
 
+    /*
+     * Note that after a ClientHello we don't know what version we are going
+     * to negotiate yet, so we don't take this branch until later
+     */
+    if (SSL_IS_TLS13(s)) {
+        if (!ossl_statem_client13_read_transition(s, mt))
+            goto err;
+        return 1;
+    }
+
     switch (st->hand_state) {
     default:
         break;
@@ -271,13 +357,67 @@ int ossl_statem_client_read_transition(SSL *s, int mt)
 }
 
 /*
- * client_write_transition() works out what handshake state to move to next
- * when the client is writing messages to be sent to the server.
+ * ossl_statem_client13_write_transition() works out what handshake state to
+ * move to next when the TLSv1.3 client is writing messages to be sent to the
+ * server.
+ */
+static WRITE_TRAN ossl_statem_client13_write_transition(SSL *s)
+{
+    OSSL_STATEM *st = &s->statem;
+
+    /*
+     * TODO(TLS1.3): This is still based on the TLSv1.2 state machine. Over time
+     * we will update this to look more like real TLSv1.3
+     */
+
+    /*
+     * Note: There are no cases for TLS_ST_BEFORE or TLS_ST_CW_CLNT_HELLO,
+     * because we haven't negotiated TLSv1.3 yet at that point. They are
+     * handled by ossl_statem_client_write_transition().
+     */
+    switch (st->hand_state) {
+    default:
+        /* Shouldn't happen */
+        return WRITE_TRAN_ERROR;
+
+    case TLS_ST_CR_FINISHED:
+        st->hand_state = (s->s3->tmp.cert_req != 0) ? TLS_ST_CW_CERT
+                                                    : TLS_ST_CW_FINISHED;
+        return WRITE_TRAN_CONTINUE;
+
+    case TLS_ST_CW_CERT:
+        /* If a non-empty Certificate we also send CertificateVerify */
+        st->hand_state = (s->s3->tmp.cert_req == 1) ? TLS_ST_CW_CERT_VRFY
+                                                    : TLS_ST_CW_FINISHED;
+        return WRITE_TRAN_CONTINUE;
+
+    case TLS_ST_CW_CERT_VRFY:
+        st->hand_state = TLS_ST_CW_FINISHED;
+        return WRITE_TRAN_CONTINUE;
+
+    case TLS_ST_CW_FINISHED:
+        st->hand_state = TLS_ST_OK;
+        ossl_statem_set_in_init(s, 0);
+        return WRITE_TRAN_CONTINUE;
+    }
+}
+
+/*
+ * ossl_statem_client_write_transition() works out what handshake state to
+ * move to next when the client is writing messages to be sent to the server.
  */
 WRITE_TRAN ossl_statem_client_write_transition(SSL *s)
 {
     OSSL_STATEM *st = &s->statem;
 
+    /*
+     * Note that immediately before/after a ClientHello we don't know what
+     * version we are going to negotiate yet, so we don't take this branch until
+     * later
+     */
+    if (SSL_IS_TLS13(s))
+        return ossl_statem_client13_write_transition(s);
+
     switch (st->hand_state) {
     default:
         /* Shouldn't happen */
@@ -497,6 +637,12 @@ WORK_STATE ossl_statem_client_post_work(SSL *s, WORK_STATE wst)
 #endif
         if (statem_flush(s) != 1)
             return WORK_MORE_B;
+
+        if (SSL_IS_TLS13(s)) {
+            if (!s->method->ssl3_enc->change_cipher_state(s,
+                        SSL3_CC_APPLICATION | SSL3_CHANGE_CIPHER_CLIENT_WRITE))
+            return WORK_ERROR;
+        }
         break;
     }
 
@@ -703,6 +849,7 @@ int tls_construct_client_hello(SSL *s, WPACKET *pkt)
     SSL_COMP *comp;
 #endif
     SSL_SESSION *sess = s->session;
+    int client_version;
 
     if (!WPACKET_set_max_size(pkt, SSL3_RT_MAX_PLAIN_LENGTH)) {
         /* Should not happen */
@@ -779,8 +926,12 @@ int tls_construct_client_hello(SSL *s, WPACKET *pkt)
      * TLS 1.0 and renegotiating with TLS 1.2. We do this by using
      * client_version in client hello and not resetting it to
      * the negotiated version.
+     *
+     * For TLS 1.3 we always set the ClientHello version to 1.2 and rely on the
+     * supported_versions extension for the real supported versions.
      */
-    if (!WPACKET_put_bytes_u16(pkt, s->client_version)
+    client_version = SSL_IS_TLS13(s) ? TLS1_2_VERSION : s->client_version;
+    if (!WPACKET_put_bytes_u16(pkt, client_version)
             || !WPACKET_memcpy(pkt, s->s3->client_random, SSL3_RANDOM_SIZE)) {
         SSLerr(SSL_F_TLS_CONSTRUCT_CLIENT_HELLO, ERR_R_INTERNAL_ERROR);
         return 0;
@@ -870,7 +1021,7 @@ int tls_construct_client_hello(SSL *s, WPACKET *pkt)
 MSG_PROCESS_RETURN dtls_process_hello_verify(SSL *s, PACKET *pkt)
 {
     int al;
-    unsigned int cookie_len;
+    size_t cookie_len;
     PACKET cookiepkt;
 
     if (!PACKET_forward(pkt, 2)
@@ -1169,6 +1320,21 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL *s, PACKET *pkt)
     }
 #endif
 
+    /*
+     * In TLSv1.3 we have some post-processing to change cipher state, otherwise
+     * we're done with this message
+     */
+    if (SSL_IS_TLS13(s)
+            && (!s->method->ssl3_enc->setup_key_block(s)
+                || !s->method->ssl3_enc->change_cipher_state(s,
+                    SSL3_CC_HANDSHAKE | SSL3_CHANGE_CIPHER_CLIENT_WRITE)
+                || !s->method->ssl3_enc->change_cipher_state(s,
+                    SSL3_CC_HANDSHAKE | SSL3_CHANGE_CIPHER_CLIENT_READ))) {
+        al = SSL_AD_INTERNAL_ERROR;
+        SSLerr(SSL_F_TLS_PROCESS_SERVER_HELLO, SSL_R_CANNOT_CHANGE_CIPHER);
+        goto f_err;
+    }
+
     return MSG_PROCESS_CONTINUE_READING;
  f_err:
     ssl3_send_alert(s, SSL3_AL_FATAL, al);
@@ -1227,7 +1393,21 @@ MSG_PROCESS_RETURN tls_process_server_certificate(SSL *s, PACKET *pkt)
     }
 
     i = ssl_verify_cert_chain(s, sk);
-    if ((s->verify_mode & SSL_VERIFY_PEER) && i <= 0) {
+    /*
+     * The documented interface is that SSL_VERIFY_PEER should be set in order
+     * for client side verification of the server certificate to take place.
+     * However, historically the code has only checked that *any* flag is set
+     * to cause server verification to take place. Use of the other flags makes
+     * no sense in client mode. An attempt to clean up the semantics was
+     * reverted because at least one application *only* set
+     * SSL_VERIFY_FAIL_IF_NO_PEER_CERT. Prior to the clean up this still caused
+     * server verification to take place, after the clean up it silently did
+     * nothing. SSL_CTX_set_verify()/SSL_set_verify() cannot validate the flags
+     * sent to them because they are void functions. Therefore, we now use the
+     * (less clean) historic behaviour of performing validation if any flag is
+     * set. The *documented* interface remains the same.
+     */
+    if (s->verify_mode != SSL_VERIFY_NONE && i <= 0) {
         al = ssl_verify_alarm_type(s->verify_result);
         SSLerr(SSL_F_TLS_PROCESS_SERVER_CERTIFICATE,
                SSL_R_CERTIFICATE_VERIFY_FAILED);
@@ -1358,18 +1538,19 @@ static int tls_process_ske_srp(SSL *s, PACKET *pkt, EVP_PKEY **pkey, int *al)
         return 0;
     }
 
+    /* TODO(size_t): Convert BN_bin2bn() calls */
     if ((s->srp_ctx.N =
          BN_bin2bn(PACKET_data(&prime),
-                   PACKET_remaining(&prime), NULL)) == NULL
+                   (int)PACKET_remaining(&prime), NULL)) == NULL
         || (s->srp_ctx.g =
             BN_bin2bn(PACKET_data(&generator),
-                      PACKET_remaining(&generator), NULL)) == NULL
+                      (int)PACKET_remaining(&generator), NULL)) == NULL
         || (s->srp_ctx.s =
             BN_bin2bn(PACKET_data(&salt),
-                      PACKET_remaining(&salt), NULL)) == NULL
+                      (int)PACKET_remaining(&salt), NULL)) == NULL
         || (s->srp_ctx.B =
             BN_bin2bn(PACKET_data(&server_pub),
-                      PACKET_remaining(&server_pub), NULL)) == NULL) {
+                      (int)PACKET_remaining(&server_pub), NULL)) == NULL) {
         *al = SSL_AD_INTERNAL_ERROR;
         SSLerr(SSL_F_TLS_PROCESS_SKE_SRP, ERR_R_BN_LIB);
         return 0;
@@ -1419,10 +1600,12 @@ static int tls_process_ske_dhe(SSL *s, PACKET *pkt, EVP_PKEY **pkey, int *al)
         goto err;
     }
 
-    p = BN_bin2bn(PACKET_data(&prime), PACKET_remaining(&prime), NULL);
-    g = BN_bin2bn(PACKET_data(&generator), PACKET_remaining(&generator), NULL);
-    bnpub_key = BN_bin2bn(PACKET_data(&pub_key), PACKET_remaining(&pub_key),
-                          NULL);
+    /* TODO(size_t): Convert these calls */
+    p = BN_bin2bn(PACKET_data(&prime), (int)PACKET_remaining(&prime), NULL);
+    g = BN_bin2bn(PACKET_data(&generator), (int)PACKET_remaining(&generator),
+                  NULL);
+    bnpub_key = BN_bin2bn(PACKET_data(&pub_key),
+                          (int)PACKET_remaining(&pub_key), NULL);
     if (p == NULL || g == NULL || bnpub_key == NULL) {
         *al = SSL_AD_INTERNAL_ERROR;
         SSLerr(SSL_F_TLS_PROCESS_SKE_DHE, ERR_R_BN_LIB);
@@ -1710,8 +1893,10 @@ MSG_PROCESS_RETURN tls_process_key_exchange(SSL *s, PACKET *pkt)
             SSLerr(SSL_F_TLS_PROCESS_KEY_EXCHANGE, ERR_R_EVP_LIB);
             goto err;
         }
+        /* TODO(size_t): Convert this call */
         if (EVP_VerifyFinal(md_ctx, PACKET_data(&signature),
-                            PACKET_remaining(&signature), pkey) <= 0) {
+                            (unsigned int)PACKET_remaining(&signature),
+                            pkey) <= 0) {
             /* bad signature */
             EVP_MD_CTX_free(md_ctx);
             al = SSL_AD_DECRYPT_ERROR;
@@ -1780,7 +1965,7 @@ MSG_PROCESS_RETURN tls_process_certificate_request(SSL *s, PACKET *pkt)
             goto err;
         }
         memcpy(s->cert->ctypes, data, ctype_num);
-        s->cert->ctype_num = (size_t)ctype_num;
+        s->cert->ctype_num = ctype_num;
         ctype_num = SSL3_CT_NUMBER;
     }
     for (i = 0; i < ctype_num; i++)
@@ -1968,7 +2153,7 @@ MSG_PROCESS_RETURN tls_process_new_session_ticket(SSL *s, PACKET *pkt)
 MSG_PROCESS_RETURN tls_process_cert_status(SSL *s, PACKET *pkt)
 {
     int al;
-    unsigned long resplen;
+    size_t resplen;
     unsigned int type;
 
     if (!PACKET_get_1(pkt, &type)
@@ -1977,7 +2162,7 @@ MSG_PROCESS_RETURN tls_process_cert_status(SSL *s, PACKET *pkt)
         SSLerr(SSL_F_TLS_PROCESS_CERT_STATUS, SSL_R_UNSUPPORTED_STATUS_TYPE);
         goto f_err;
     }
-    if (!PACKET_get_net_3(pkt, &resplen)
+    if (!PACKET_get_net_3_len(pkt, &resplen)
         || PACKET_remaining(pkt) != resplen) {
         al = SSL_AD_DECODE_ERROR;
         SSLerr(SSL_F_TLS_PROCESS_CERT_STATUS, SSL_R_LENGTH_MISMATCH);
@@ -2002,34 +2187,22 @@ MSG_PROCESS_RETURN tls_process_cert_status(SSL *s, PACKET *pkt)
     return MSG_PROCESS_ERROR;
 }
 
-MSG_PROCESS_RETURN tls_process_server_done(SSL *s, PACKET *pkt)
+/*
+ * Perform miscellaneous checks and processing after we have received the
+ * server's initial flight. In TLS1.3 this is after the Server Finished message.
+ * In <=TLS1.2 this is after the ServerDone message.
+ *
+ * Returns 1 on success or 0 on failure.
+ */
+int tls_process_initial_server_flight(SSL *s, int *al)
 {
-    if (PACKET_remaining(pkt) > 0) {
-        /* should contain no data */
-        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
-        SSLerr(SSL_F_TLS_PROCESS_SERVER_DONE, SSL_R_LENGTH_MISMATCH);
-        ossl_statem_set_error(s);
-        return MSG_PROCESS_ERROR;
-    }
-#ifndef OPENSSL_NO_SRP
-    if (s->s3->tmp.new_cipher->algorithm_mkey & SSL_kSRP) {
-        if (SRP_Calc_A_param(s) <= 0) {
-            SSLerr(SSL_F_TLS_PROCESS_SERVER_DONE, SSL_R_SRP_A_CALC);
-            ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
-            ossl_statem_set_error(s);
-            return MSG_PROCESS_ERROR;
-        }
-    }
-#endif
-
     /*
      * at this point we check that we have the required stuff from
      * the server
      */
     if (!ssl3_check_cert_and_algorithm(s)) {
-        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
-        ossl_statem_set_error(s);
-        return MSG_PROCESS_ERROR;
+        *al = SSL_AD_HANDSHAKE_FAILURE;
+        return 0;
     }
 
     /*
@@ -2041,28 +2214,56 @@ MSG_PROCESS_RETURN tls_process_server_done(SSL *s, PACKET *pkt)
         int ret;
         ret = s->ctx->tlsext_status_cb(s, s->ctx->tlsext_status_arg);
         if (ret == 0) {
-            ssl3_send_alert(s, SSL3_AL_FATAL,
-                            SSL_AD_BAD_CERTIFICATE_STATUS_RESPONSE);
-            SSLerr(SSL_F_TLS_PROCESS_SERVER_DONE,
+            *al = SSL_AD_BAD_CERTIFICATE_STATUS_RESPONSE;
+            SSLerr(SSL_F_TLS_PROCESS_INITIAL_SERVER_FLIGHT,
                    SSL_R_INVALID_STATUS_RESPONSE);
-            return MSG_PROCESS_ERROR;
+            return 0;
         }
         if (ret < 0) {
-            ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
-            SSLerr(SSL_F_TLS_PROCESS_SERVER_DONE, ERR_R_MALLOC_FAILURE);
-            return MSG_PROCESS_ERROR;
+            *al = SSL_AD_INTERNAL_ERROR;
+            SSLerr(SSL_F_TLS_PROCESS_INITIAL_SERVER_FLIGHT,
+                   ERR_R_MALLOC_FAILURE);
+            return 0;
         }
     }
 #ifndef OPENSSL_NO_CT
     if (s->ct_validation_callback != NULL) {
         /* Note we validate the SCTs whether or not we abort on error */
         if (!ssl_validate_ct(s) && (s->verify_mode & SSL_VERIFY_PEER)) {
-            ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
-            return MSG_PROCESS_ERROR;
+            *al = SSL_AD_HANDSHAKE_FAILURE;
+            return 0;
         }
     }
 #endif
 
+    return 1;
+}
+
+MSG_PROCESS_RETURN tls_process_server_done(SSL *s, PACKET *pkt)
+{
+    int al = SSL_AD_INTERNAL_ERROR;
+
+    if (PACKET_remaining(pkt) > 0) {
+        /* should contain no data */
+        al = SSL_AD_DECODE_ERROR;
+        SSLerr(SSL_F_TLS_PROCESS_SERVER_DONE, SSL_R_LENGTH_MISMATCH);
+        goto err;
+    }
+#ifndef OPENSSL_NO_SRP
+    if (s->s3->tmp.new_cipher->algorithm_mkey & SSL_kSRP) {
+        if (SRP_Calc_A_param(s) <= 0) {
+            SSLerr(SSL_F_TLS_PROCESS_SERVER_DONE, SSL_R_SRP_A_CALC);
+            goto err;
+        }
+    }
+#endif
+
+    /*
+     * Error queue messages are generated directly by this function
+     */
+    if (!tls_process_initial_server_flight(s, &al))
+        goto err;
+
 #ifndef OPENSSL_NO_SCTP
     /* Only applies to renegotiation */
     if (SSL_IS_DTLS(s) && BIO_dgram_is_sctp(SSL_get_wbio(s))
@@ -2071,6 +2272,11 @@ MSG_PROCESS_RETURN tls_process_server_done(SSL *s, PACKET *pkt)
     else
 #endif
         return MSG_PROCESS_FINISHED_READING;
+
+ err:
+    ssl3_send_alert(s, SSL3_AL_FATAL, al);
+    ossl_statem_set_error(s);
+    return MSG_PROCESS_ERROR;
 }
 
 static int tls_construct_cke_psk_preamble(SSL *s, WPACKET *pkt, int *al)
@@ -2191,7 +2397,8 @@ static int tls_construct_cke_rsa(SSL *s, WPACKET *pkt, int *al)
 
     pms[0] = s->client_version >> 8;
     pms[1] = s->client_version & 0xff;
-    if (RAND_bytes(pms + 2, pmslen - 2) <= 0) {
+    /* TODO(size_t): Convert this function */
+    if (RAND_bytes(pms + 2, (int)(pmslen - 2)) <= 0) {
         goto err;
     }
 
@@ -2257,7 +2464,7 @@ static int tls_construct_cke_dhe(SSL *s, WPACKET *pkt, int *al)
     ckey = ssl_generate_pkey(skey);
     dh_clnt = EVP_PKEY_get0_DH(ckey);
 
-    if (dh_clnt == NULL || ssl_derive(s, ckey, skey) == 0)
+    if (dh_clnt == NULL || ssl_derive(s, ckey, skey, 0) == 0)
         goto err;
 
     /* send off the data */
@@ -2281,7 +2488,7 @@ static int tls_construct_cke_ecdhe(SSL *s, WPACKET *pkt, int *al)
 {
 #ifndef OPENSSL_NO_EC
     unsigned char *encodedPoint = NULL;
-    int encoded_pt_len = 0;
+    size_t encoded_pt_len = 0;
     EVP_PKEY *ckey = NULL, *skey = NULL;
     int ret = 0;
 
@@ -2293,7 +2500,7 @@ static int tls_construct_cke_ecdhe(SSL *s, WPACKET *pkt, int *al)
 
     ckey = ssl_generate_pkey(skey);
 
-    if (ssl_derive(s, ckey, skey) == 0) {
+    if (ssl_derive(s, ckey, skey, 0) == 0) {
         SSLerr(SSL_F_TLS_CONSTRUCT_CKE_ECDHE, ERR_R_EVP_LIB);
         goto err;
     }
@@ -2373,8 +2580,10 @@ static int tls_construct_cke_gost(SSL *s, WPACKET *pkt, int *al)
     }
 
     if (EVP_PKEY_encrypt_init(pkey_ctx) <= 0
-        /* Generate session key */
-        || RAND_bytes(pms, pmslen) <= 0) {
+        /* Generate session key
+         * TODO(size_t): Convert this function
+         */
+        || RAND_bytes(pms, (int)pmslen) <= 0) {
         *al = SSL_AD_INTERNAL_ERROR;
         SSLerr(SSL_F_TLS_CONSTRUCT_CKE_GOST, ERR_R_INTERNAL_ERROR);
         goto err;
@@ -2599,6 +2808,7 @@ int tls_construct_client_verify(SSL *s, WPACKET *pkt)
         SSLerr(SSL_F_TLS_CONSTRUCT_CLIENT_VERIFY, ERR_R_INTERNAL_ERROR);
         goto err;
     }
+
     if (SSL_USE_SIGALGS(s)&& !tls12_get_sigandhash(pkt, pkey, md)) {
         SSLerr(SSL_F_TLS_CONSTRUCT_CLIENT_VERIFY, ERR_R_INTERNAL_ERROR);
         goto err;
@@ -2615,7 +2825,7 @@ int tls_construct_client_verify(SSL *s, WPACKET *pkt)
         || !EVP_SignUpdate(mctx, hdata, hdatalen)
         || (s->version == SSL3_VERSION
             && !EVP_MD_CTX_ctrl(mctx, EVP_CTRL_SSL3_MASTER_SECRET,
-                                s->session->master_key_length,
+                                (int)s->session->master_key_length,
                                 s->session->master_key))
         || !EVP_SignFinal(mctx, sig, &u, pkey)) {
         SSLerr(SSL_F_TLS_CONSTRUCT_CLIENT_VERIFY, ERR_R_EVP_LIB);