Add server side support for TLSv1.3 downgrade mechanism
[openssl.git] / ssl / statem / statem_srvr.c
index 56db987ee43426d0299c20f19a5951871ed3d2ab..e2c47994b8c2ba8aaf0012eb1e429f8f64b2fcd1 100644 (file)
@@ -93,6 +93,17 @@ static int ossl_statem_server13_read_transition(SSL *s, int mt)
         }
         break;
 
+    case TLS_ST_EARLY_DATA:
+        if (s->ext.early_data == SSL_EARLY_DATA_ACCEPTED) {
+            if (mt == SSL3_MT_END_OF_EARLY_DATA) {
+                st->hand_state = TLS_ST_SR_END_OF_EARLY_DATA;
+                return 1;
+            }
+            break;
+        }
+        /* Fall through */
+
+    case TLS_ST_SR_END_OF_EARLY_DATA:
     case TLS_ST_SW_FINISHED:
         if (s->s3->tmp.cert_request) {
             if (mt == SSL3_MT_CERTIFICATE) {
@@ -143,9 +154,6 @@ static int ossl_statem_server13_read_transition(SSL *s, int mt)
     }
 
     /* No valid transition found */
-    ssl3_send_alert(s, SSL3_AL_FATAL, SSL3_AD_UNEXPECTED_MESSAGE);
-    SSLerr(SSL_F_OSSL_STATEM_SERVER13_READ_TRANSITION,
-           SSL_R_UNEXPECTED_MESSAGE);
     return 0;
 }
 
@@ -412,10 +420,6 @@ static WRITE_TRAN ossl_statem_server13_write_transition(SSL *s)
         return WRITE_TRAN_ERROR;
 
     case TLS_ST_OK:
-        if (s->early_data_state == SSL_EARLY_DATA_FINISHED_READING) {
-            st->hand_state = TLS_ST_SW_FINISHED;
-            return WRITE_TRAN_FINISHED;
-        }
         if (s->key_update != SSL_KEY_UPDATE_NONE) {
             st->hand_state = TLS_ST_SW_KEY_UPDATE;
             return WRITE_TRAN_CONTINUE;
@@ -460,11 +464,10 @@ static WRITE_TRAN ossl_statem_server13_write_transition(SSL *s)
         return WRITE_TRAN_CONTINUE;
 
     case TLS_ST_SW_FINISHED:
-        if (s->early_data_state == SSL_EARLY_DATA_ACCEPTING) {
-            st->hand_state = TLS_ST_OK;
-            ossl_statem_set_in_init(s, 0);
-            return WRITE_TRAN_CONTINUE;
-        }
+        st->hand_state = TLS_ST_EARLY_DATA;
+        return WRITE_TRAN_CONTINUE;
+
+    case TLS_ST_EARLY_DATA:
         return WRITE_TRAN_FINISHED;
 
     case TLS_ST_SR_FINISHED:
@@ -489,7 +492,6 @@ static WRITE_TRAN ossl_statem_server13_write_transition(SSL *s)
     case TLS_ST_SW_KEY_UPDATE:
     case TLS_ST_SW_SESSION_TICKET:
         st->hand_state = TLS_ST_OK;
-        ossl_statem_set_in_init(s, 0);
         return WRITE_TRAN_CONTINUE;
     }
 }
@@ -535,7 +537,6 @@ WRITE_TRAN ossl_statem_server_write_transition(SSL *s)
 
     case TLS_ST_SW_HELLO_REQ:
         st->hand_state = TLS_ST_OK;
-        ossl_statem_set_in_init(s, 0);
         return WRITE_TRAN_CONTINUE;
 
     case TLS_ST_SR_CLNT_HELLO:
@@ -602,7 +603,6 @@ WRITE_TRAN ossl_statem_server_write_transition(SSL *s)
     case TLS_ST_SR_FINISHED:
         if (s->hit) {
             st->hand_state = TLS_ST_OK;
-            ossl_statem_set_in_init(s, 0);
             return WRITE_TRAN_CONTINUE;
         } else if (s->ext.ticket_expected) {
             st->hand_state = TLS_ST_SW_SESSION_TICKET;
@@ -624,7 +624,6 @@ WRITE_TRAN ossl_statem_server_write_transition(SSL *s)
             return WRITE_TRAN_FINISHED;
         }
         st->hand_state = TLS_ST_OK;
-        ossl_statem_set_in_init(s, 0);
         return WRITE_TRAN_CONTINUE;
     }
 }
@@ -708,6 +707,11 @@ WORK_STATE ossl_statem_server_pre_work(SSL *s, WORK_STATE wst)
         }
         return WORK_FINISHED_CONTINUE;
 
+    case TLS_ST_EARLY_DATA:
+        if (s->early_data_state != SSL_EARLY_DATA_ACCEPTING)
+            return WORK_FINISHED_CONTINUE;
+        /* Fall through */
+
     case TLS_ST_OK:
         return tls_finish_handshake(s, wst, 1);
     }
@@ -952,6 +956,11 @@ int ossl_statem_server_construct_message(SSL *s, WPACKET *pkt,
         *mt = SSL3_MT_FINISHED;
         break;
 
+    case TLS_ST_EARLY_DATA:
+        *confunc = NULL;
+        *mt = SSL3_MT_DUMMY;
+        break;
+
     case TLS_ST_SW_ENCRYPTED_EXTENSIONS:
         *confunc = tls_construct_encrypted_extensions;
         *mt = SSL3_MT_ENCRYPTED_EXTENSIONS;
@@ -1007,6 +1016,9 @@ size_t ossl_statem_server_max_message_size(SSL *s)
     case TLS_ST_SR_CLNT_HELLO:
         return CLIENT_HELLO_MAX_LENGTH;
 
+    case TLS_ST_SR_END_OF_EARLY_DATA:
+        return END_OF_EARLY_DATA_MAX_LENGTH;
+
     case TLS_ST_SR_CERT:
         return s->max_cert_list;
 
@@ -1047,6 +1059,9 @@ MSG_PROCESS_RETURN ossl_statem_server_process_message(SSL *s, PACKET *pkt)
     case TLS_ST_SR_CLNT_HELLO:
         return tls_process_client_hello(s, pkt);
 
+    case TLS_ST_SR_END_OF_EARLY_DATA:
+        return tls_process_end_of_early_data(s, pkt);
+
     case TLS_ST_SR_CERT:
         return tls_process_client_certificate(s, pkt);
 
@@ -1113,15 +1128,6 @@ WORK_STATE ossl_statem_server_post_process_message(SSL *s, WORK_STATE wst)
     return WORK_FINISHED_CONTINUE;
 }
 
-int ossl_statem_finish_early_data(SSL *s)
-{
-    if (!s->method->ssl3_enc->change_cipher_state(s,
-                SSL3_CC_HANDSHAKE | SSL3_CHANGE_CIPHER_SERVER_READ))
-        return 0;
-
-    return 1;
-}
-
 #ifndef OPENSSL_NO_SRP
 static int ssl_check_srp_ext_ClientHello(SSL *s, int *al)
 {
@@ -1470,6 +1476,7 @@ static int tls_early_post_process_client_hello(SSL *s, int *al)
     STACK_OF(SSL_CIPHER) *ciphers = NULL;
     STACK_OF(SSL_CIPHER) *scsvs = NULL;
     CLIENTHELLO_MSG *clienthello = s->clienthello;
+    DOWNGRADE dgrd = DOWNGRADE_NONE;
 
     *al = SSL_AD_INTERNAL_ERROR;
     /* Finished parsing the ClientHello, now we can start processing it */
@@ -1510,7 +1517,7 @@ static int tls_early_post_process_client_hello(SSL *s, int *al)
      * versions are potentially compatible. Version negotiation comes later.
      */
     if (!SSL_IS_DTLS(s)) {
-        protverr = ssl_choose_server_version(s, clienthello);
+        protverr = ssl_choose_server_version(s, clienthello, &dgrd);
     } else if (s->method->version != DTLS_ANY_VERSION &&
                DTLS_VERSION_LT((int)clienthello->legacy_version, s->version)) {
         protverr = SSL_R_VERSION_TOO_LOW;
@@ -1528,6 +1535,14 @@ static int tls_early_post_process_client_hello(SSL *s, int *al)
         goto err;
     }
 
+    /* TLSv1.3 specifies that a ClientHello must end on a record boundary */
+    if (SSL_IS_TLS13(s) && RECORD_LAYER_processed_read_pending(&s->rlayer)) {
+        *al = SSL_AD_UNEXPECTED_MESSAGE;
+        SSLerr(SSL_F_TLS_EARLY_POST_PROCESS_CLIENT_HELLO,
+               SSL_R_NOT_ON_RECORD_BOUNDARY);
+        goto err;
+    }
+
     if (SSL_IS_DTLS(s)) {
         /* Empty cookie was already handled above by returning early. */
         if (SSL_get_options(s) & SSL_OP_COOKIE_EXCHANGE) {
@@ -1551,7 +1566,7 @@ static int tls_early_post_process_client_hello(SSL *s, int *al)
             s->d1->cookie_verified = 1;
         }
         if (s->method->version == DTLS_ANY_VERSION) {
-            protverr = ssl_choose_server_version(s, clienthello);
+            protverr = ssl_choose_server_version(s, clienthello, &dgrd);
             if (protverr != 0) {
                 SSLerr(SSL_F_TLS_EARLY_POST_PROCESS_CLIENT_HELLO, protverr);
                 s->version = s->client_version;
@@ -1708,7 +1723,7 @@ static int tls_early_post_process_client_hello(SSL *s, int *al)
     {
         unsigned char *pos;
         pos = s->s3->server_random;
-        if (ssl_fill_hello_random(s, 1, pos, SSL3_RANDOM_SIZE) <= 0) {
+        if (ssl_fill_hello_random(s, 1, pos, SSL3_RANDOM_SIZE, dgrd) <= 0) {
             goto err;
         }
     }
@@ -1835,12 +1850,7 @@ static int tls_early_post_process_client_hello(SSL *s, int *al)
      * Given s->session->ciphers and SSL_get_ciphers, we must pick a cipher
      */
 
-    if (!s->hit) {
-#ifdef OPENSSL_NO_COMP
-        s->session->compress_meth = 0;
-#else
-        s->session->compress_meth = (comp == NULL) ? 0 : comp->id;
-#endif
+    if (!s->hit || s->hello_retry_request) {
         sk_SSL_CIPHER_free(s->session->ciphers);
         s->session->ciphers = ciphers;
         if (ciphers == NULL) {
@@ -1849,6 +1859,14 @@ static int tls_early_post_process_client_hello(SSL *s, int *al)
             goto err;
         }
         ciphers = NULL;
+    }
+
+    if (!s->hit) {
+#ifdef OPENSSL_NO_COMP
+        s->session->compress_meth = 0;
+#else
+        s->session->compress_meth = (comp == NULL) ? 0 : comp->id;
+#endif
         if (!tls1_set_server_sigalgs(s)) {
             SSLerr(SSL_F_TLS_EARLY_POST_PROCESS_CLIENT_HELLO, SSL_R_CLIENTHELLO_TLSEXT);
             goto err;
@@ -1937,7 +1955,7 @@ WORK_STATE tls_post_process_client_hello(SSL *s, WORK_STATE wst)
         wst = WORK_MORE_B;
     }
     if (wst == WORK_MORE_B) {
-        if (!s->hit) {
+        if (!s->hit || s->hello_retry_request) {
             /* Let cert callback update server certificates if required */
             if (s->cert->cert_cb) {
                 int rv = s->cert->cert_cb(s, s->cert->cert_cb_arg);
@@ -1961,18 +1979,30 @@ WORK_STATE tls_post_process_client_hello(SSL *s, WORK_STATE wst)
                        SSL_R_NO_SHARED_CIPHER);
                 goto f_err;
             }
-            s->s3->tmp.new_cipher = cipher;
-            if (!tls_choose_sigalg(s, &al))
+            if (SSL_IS_TLS13(s) && s->s3->tmp.new_cipher != NULL
+                    && s->s3->tmp.new_cipher->id != cipher->id) {
+                /*
+                 * A previous HRR picked a different ciphersuite to the one we
+                 * just selected. Something must have changed.
+                 */
+                al = SSL_AD_ILLEGAL_PARAMETER;
+                SSLerr(SSL_F_TLS_POST_PROCESS_CLIENT_HELLO, SSL_R_BAD_CIPHER);
                 goto f_err;
-            /* check whether we should disable session resumption */
-            if (s->not_resumable_session_cb != NULL)
-                s->session->not_resumable =
-                    s->not_resumable_session_cb(s, ((cipher->algorithm_mkey
-                                                    & (SSL_kDHE | SSL_kECDHE))
-                                                   != 0));
-            if (s->session->not_resumable)
-                /* do not send a session ticket */
-                s->ext.ticket_expected = 0;
+            }
+            s->s3->tmp.new_cipher = cipher;
+            if (!s->hit) {
+                if (!tls_choose_sigalg(s, &al))
+                    goto f_err;
+                /* check whether we should disable session resumption */
+                if (s->not_resumable_session_cb != NULL)
+                    s->session->not_resumable =
+                        s->not_resumable_session_cb(s, ((cipher->algorithm_mkey
+                                                        & (SSL_kDHE | SSL_kECDHE))
+                                                       != 0));
+                if (s->session->not_resumable)
+                    /* do not send a session ticket */
+                    s->ext.ticket_expected = 0;
+            }
         } else {
             /* Session-id reuse */
             s->s3->tmp.new_cipher = s->session->cipher;
@@ -2470,8 +2500,7 @@ int tls_construct_server_key_exchange(SSL *s, WPACKET *pkt)
 
 int tls_construct_certificate_request(SSL *s, WPACKET *pkt)
 {
-    int i;
-    STACK_OF(X509_NAME) *sk = NULL;
+    int al = SSL_AD_INTERNAL_ERROR;
 
     if (SSL_IS_TLS13(s)) {
         /* TODO(TLS1.3) for now send empty request context */
@@ -2480,14 +2509,21 @@ int tls_construct_certificate_request(SSL *s, WPACKET *pkt)
                    ERR_R_INTERNAL_ERROR);
             goto err;
         }
-    } else {
-        /* get the list of acceptable cert types */
-        if (!WPACKET_start_sub_packet_u8(pkt)
-            || !ssl3_get_req_cert_type(s, pkt) || !WPACKET_close(pkt)) {
+
+        if (!tls_construct_extensions(s, pkt, EXT_TLS1_3_CERTIFICATE_REQUEST,
+                                      NULL, 0, &al)) {
             SSLerr(SSL_F_TLS_CONSTRUCT_CERTIFICATE_REQUEST,
                    ERR_R_INTERNAL_ERROR);
             goto err;
         }
+        goto done;
+    }
+
+    /* get the list of acceptable cert types */
+    if (!WPACKET_start_sub_packet_u8(pkt)
+        || !ssl3_get_req_cert_type(s, pkt) || !WPACKET_close(pkt)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_CERTIFICATE_REQUEST, ERR_R_INTERNAL_ERROR);
+        goto err;
     }
 
     if (SSL_USE_SIGALGS(s)) {
@@ -2495,6 +2531,7 @@ int tls_construct_certificate_request(SSL *s, WPACKET *pkt)
         size_t nl = tls12_get_psigalgs(s, 1, &psigs);
 
         if (!WPACKET_start_sub_packet_u16(pkt)
+                || !WPACKET_set_flags(pkt, WPACKET_FLAGS_NON_ZERO_LENGTH)
                 || !tls12_copy_sigalgs(s, pkt, psigs, nl)
                 || !WPACKET_close(pkt)) {
             SSLerr(SSL_F_TLS_CONSTRUCT_CERTIFICATE_REQUEST,
@@ -2503,49 +2540,16 @@ int tls_construct_certificate_request(SSL *s, WPACKET *pkt)
         }
     }
 
-    /* Start sub-packet for client CA list */
-    if (!WPACKET_start_sub_packet_u16(pkt)) {
-        SSLerr(SSL_F_TLS_CONSTRUCT_CERTIFICATE_REQUEST, ERR_R_INTERNAL_ERROR);
-        goto err;
-    }
-
-    sk = SSL_get_client_CA_list(s);
-    if (sk != NULL) {
-        for (i = 0; i < sk_X509_NAME_num(sk); i++) {
-            unsigned char *namebytes;
-            X509_NAME *name = sk_X509_NAME_value(sk, i);
-            int namelen;
-
-            if (name == NULL
-                    || (namelen = i2d_X509_NAME(name, NULL)) < 0
-                    || !WPACKET_sub_allocate_bytes_u16(pkt, namelen,
-                                                       &namebytes)
-                    || i2d_X509_NAME(name, &namebytes) != namelen) {
-                SSLerr(SSL_F_TLS_CONSTRUCT_CERTIFICATE_REQUEST,
-                       ERR_R_INTERNAL_ERROR);
-                goto err;
-            }
-        }
-    }
-    /* else no CA names */
-    if (!WPACKET_close(pkt)) {
-        SSLerr(SSL_F_TLS_CONSTRUCT_CERTIFICATE_REQUEST, ERR_R_INTERNAL_ERROR);
-        goto err;
-    }
-    /*
-     * TODO(TLS1.3) implement configurable certificate_extensions
-     * For now just send zero length extensions.
-     */
-    if (SSL_IS_TLS13(s) && !WPACKET_put_bytes_u16(pkt, 0)) {
+    if (!construct_ca_names(s, pkt)) {
         SSLerr(SSL_F_TLS_CONSTRUCT_CERTIFICATE_REQUEST, ERR_R_INTERNAL_ERROR);
         goto err;
     }
 
+ done:
     s->s3->tmp.cert_request = 1;
-
     return 1;
  err:
-    ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
+    ssl3_send_alert(s, SSL3_AL_FATAL, al);
     return 0;
 }
 
@@ -3277,7 +3281,7 @@ MSG_PROCESS_RETURN tls_process_client_certificate(SSL *s, PACKET *pkt)
                  (s->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT)) {
             SSLerr(SSL_F_TLS_PROCESS_CLIENT_CERTIFICATE,
                    SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
-            al = SSL_AD_HANDSHAKE_FAILURE;
+            al = SSL_AD_CERTIFICATE_REQUIRED;
             goto f_err;
         }
         /* No client certificate so digest cached records */
@@ -3401,6 +3405,18 @@ int tls_construct_new_session_ticket(SSL *s, WPACKET *pkt)
             goto err;
         s->session->ext.tick_age_add = age_add_u.age_add;
         s->session->time = (long)time(NULL);
+        if (s->s3->alpn_selected != NULL) {
+            OPENSSL_free(s->session->ext.alpn_selected);
+            s->session->ext.alpn_selected =
+                OPENSSL_memdup(s->s3->alpn_selected, s->s3->alpn_selected_len);
+            if (s->session->ext.alpn_selected == NULL) {
+                SSLerr(SSL_F_TLS_CONSTRUCT_NEW_SESSION_TICKET,
+                       ERR_R_MALLOC_FAILURE);
+                goto err;
+            }
+            s->session->ext.alpn_selected_len = s->s3->alpn_selected_len;
+        }
+        s->session->ext.max_early_data = s->max_early_data;
     }
 
     /* get session encoding length */
@@ -3410,13 +3426,13 @@ int tls_construct_new_session_ticket(SSL *s, WPACKET *pkt)
      * long
      */
     if (slen_full == 0 || slen_full > 0xFF00) {
-        ossl_statem_set_error(s);
-        return 0;
+        SSLerr(SSL_F_TLS_CONSTRUCT_NEW_SESSION_TICKET, ERR_R_INTERNAL_ERROR);
+        goto err;
     }
     senc = OPENSSL_malloc(slen_full);
     if (senc == NULL) {
-        ossl_statem_set_error(s);
-        return 0;
+        SSLerr(SSL_F_TLS_CONSTRUCT_NEW_SESSION_TICKET, ERR_R_MALLOC_FAILURE);
+        goto err;
     }
 
     ctx = EVP_CIPHER_CTX_new();
@@ -3545,6 +3561,7 @@ int tls_construct_new_session_ticket(SSL *s, WPACKET *pkt)
 
     return 1;
  err:
+    ossl_statem_set_error(s);
     OPENSSL_free(senc);
     EVP_CIPHER_CTX_free(ctx);
     HMAC_CTX_free(hctx);
@@ -3634,17 +3651,18 @@ static int tls_construct_encrypted_extensions(SSL *s, WPACKET *pkt)
 static int tls_construct_hello_retry_request(SSL *s, WPACKET *pkt)
 {
     int al = SSL_AD_INTERNAL_ERROR;
+    size_t len = 0;
 
     /*
      * TODO(TLS1.3): Remove the DRAFT version before release
      * (should be s->version)
      */
     if (!WPACKET_put_bytes_u16(pkt, TLS1_3_VERSION_DRAFT)
+            || !s->method->put_cipher_by_char(s->s3->tmp.new_cipher, pkt, &len)
             || !tls_construct_extensions(s, pkt, EXT_TLS1_3_HELLO_RETRY_REQUEST,
                                          NULL, 0, &al)) {
         SSLerr(SSL_F_TLS_CONSTRUCT_HELLO_RETRY_REQUEST, ERR_R_INTERNAL_ERROR);
-        ssl3_send_alert(s, SSL3_AL_FATAL, al);
-        return 0;
+        goto err;
     }
 
     /* Ditch the session. We'll create a new one next time around */
@@ -3652,5 +3670,57 @@ static int tls_construct_hello_retry_request(SSL *s, WPACKET *pkt)
     s->session = NULL;
     s->hit = 0;
 
+    /*
+     * Re-initialise the Transcript Hash. We're going to prepopulate it with
+     * a synthetic message_hash in place of ClientHello1.
+     */
+    if (!create_synthetic_message_hash(s))
+        goto err;
+
     return 1;
+ err:
+    ssl3_send_alert(s, SSL3_AL_FATAL, al);
+    return 0;
+}
+
+MSG_PROCESS_RETURN tls_process_end_of_early_data(SSL *s, PACKET *pkt)
+{
+    int al = SSL_AD_INTERNAL_ERROR;
+
+    if (PACKET_remaining(pkt) != 0) {
+        al = SSL_AD_DECODE_ERROR;
+        SSLerr(SSL_F_TLS_PROCESS_END_OF_EARLY_DATA, SSL_R_LENGTH_MISMATCH);
+        ossl_statem_set_error(s);
+        return MSG_PROCESS_ERROR;
+    }
+
+    if (s->early_data_state != SSL_EARLY_DATA_READING
+            && s->early_data_state != SSL_EARLY_DATA_READ_RETRY) {
+        SSLerr(SSL_F_TLS_PROCESS_END_OF_EARLY_DATA, ERR_R_INTERNAL_ERROR);
+        goto err;
+    }
+
+    /*
+     * EndOfEarlyData signals a key change so the end of the message must be on
+     * a record boundary.
+     */
+    if (RECORD_LAYER_processed_read_pending(&s->rlayer)) {
+        al = SSL_AD_UNEXPECTED_MESSAGE;
+        SSLerr(SSL_F_TLS_PROCESS_END_OF_EARLY_DATA,
+               SSL_R_NOT_ON_RECORD_BOUNDARY);
+        goto err;
+    }
+
+    s->early_data_state = SSL_EARLY_DATA_FINISHED_READING;
+    if (!s->method->ssl3_enc->change_cipher_state(s,
+                SSL3_CC_HANDSHAKE | SSL3_CHANGE_CIPHER_SERVER_READ)) {
+        SSLerr(SSL_F_TLS_PROCESS_END_OF_EARLY_DATA, ERR_R_INTERNAL_ERROR);
+        goto err;
+    }
+
+    return MSG_PROCESS_CONTINUE_READING;
+ err:
+    ssl3_send_alert(s, SSL3_AL_FATAL, al);
+    ossl_statem_set_error(s);
+    return MSG_PROCESS_ERROR;
 }