Don't interleave handshake and other record types in TLSv1.3

In TLSv1.3 it is illegal to interleave handshake records with non handshake
records.

Fixes #8189

Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/8191)

crypto/err/openssl.txt

@@ -2796,6 +2796,8 @@ SSL_R_MISSING_SRP_PARAM:358:can't find SRP server param
 SSL_R_MISSING_SUPPORTED_GROUPS_EXTENSION:209:missing supported groups extension
 SSL_R_MISSING_TMP_DH_KEY:171:missing tmp dh key
 SSL_R_MISSING_TMP_ECDH_KEY:311:missing tmp ecdh key
+SSL_R_MIXED_HANDSHAKE_AND_NON_HANDSHAKE_DATA:293:\
+	mixed handshake and non handshake data
 SSL_R_NOT_ON_RECORD_BOUNDARY:182:not on record boundary
 SSL_R_NOT_REPLACING_CERTIFICATE:289:not replacing certificate
 SSL_R_NOT_SERVER:284:not server

include/openssl/sslerr.h

@@ -1,6 +1,6 @@
 /*
  * Generated by util/mkerr.pl DO NOT EDIT
- * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
@@ -596,6 +596,7 @@ int ERR_load_SSL_strings(void);
 # define SSL_R_MISSING_SUPPORTED_GROUPS_EXTENSION         209
 # define SSL_R_MISSING_TMP_DH_KEY                         171
 # define SSL_R_MISSING_TMP_ECDH_KEY                       311
+# define SSL_R_MIXED_HANDSHAKE_AND_NON_HANDSHAKE_DATA     293
 # define SSL_R_NOT_ON_RECORD_BOUNDARY                     182
 # define SSL_R_NOT_REPLACING_CERTIFICATE                  289
 # define SSL_R_NOT_SERVER                                 284

ssl/record/rec_layer_s3.c

@@ -1363,6 +1363,14 @@ int ssl3_read_bytes(SSL *s, int type, int *recvd_type, unsigned char *buf,
     } while (num_recs == 0);
     rr = &rr[curr_rec];
 
+    if (s->rlayer.handshake_fragment_len > 0
+            && SSL3_RECORD_get_type(rr) != SSL3_RT_HANDSHAKE
+            && SSL_IS_TLS13(s)) {
+        SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_READ_BYTES,
+                 SSL_R_MIXED_HANDSHAKE_AND_NON_HANDSHAKE_DATA);
+        return -1;
+    }
+
     /*
      * Reset the count of consecutive warning alerts if we've got a non-empty
      * record that isn't an alert.

ssl/ssl_err.c

@@ -1,6 +1,6 @@
 /*
  * Generated by util/mkerr.pl DO NOT EDIT
- * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
@@ -965,6 +965,8 @@ static const ERR_STRING_DATA SSL_str_reasons[] = {
     {ERR_PACK(ERR_LIB_SSL, 0, SSL_R_MISSING_TMP_DH_KEY), "missing tmp dh key"},
     {ERR_PACK(ERR_LIB_SSL, 0, SSL_R_MISSING_TMP_ECDH_KEY),
     "missing tmp ecdh key"},
+    {ERR_PACK(ERR_LIB_SSL, 0, SSL_R_MIXED_HANDSHAKE_AND_NON_HANDSHAKE_DATA),
+    "mixed handshake and non handshake data"},
     {ERR_PACK(ERR_LIB_SSL, 0, SSL_R_NOT_ON_RECORD_BOUNDARY),
     "not on record boundary"},
     {ERR_PACK(ERR_LIB_SSL, 0, SSL_R_NOT_REPLACING_CERTIFICATE),