diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c index 08cfe221ba..052df7e66e 100644 --- a/library/ssl_tls13_client.c +++ b/library/ssl_tls13_client.c @@ -1925,7 +1925,6 @@ static int ssl_tls13_postprocess_server_hello(mbedtls_ssl_context *ssl) mbedtls_ssl_set_inbound_transform(ssl, handshake->transform_handshake); MBEDTLS_SSL_DEBUG_MSG(1, ("Switch to handshake keys for inbound traffic")); - ssl->session_negotiate->ciphersuite = handshake->ciphersuite_info->id; ssl->session_in = ssl->session_negotiate; cleanup: @@ -2153,9 +2152,7 @@ static int ssl_tls13_process_encrypted_extensions(mbedtls_ssl_context *ssl) int ret; unsigned char *buf; size_t buf_len; -#if defined(MBEDTLS_SSL_EARLY_DATA) mbedtls_ssl_handshake_params *handshake = ssl->handshake; -#endif MBEDTLS_SSL_DEBUG_MSG(2, ("=> parse encrypted extensions")); @@ -2185,11 +2182,19 @@ static int ssl_tls13_process_encrypted_extensions(mbedtls_ssl_context *ssl) * - The selected cipher suite * - The selected ALPN [RFC7301] protocol, if any * - * We check here that when early data is involved the server - * selected the cipher suite associated to the pre-shared key - * as it must have. + * The server has sent an early data extension in its Encrypted + * Extension message thus accepted to receive early data. We + * check here that the additional constraints on the handshake + * parameters, when early data are exchanged, are met, + * namely: + * - a PSK has been selected for the handshake + * - the selected PSK for the handshake was the first one proposed + * by the client. + * - the selected ciphersuite for the handshake is the ciphersuite + * associated with the selected PSK. */ - if (handshake->selected_identity != 0 || + if ((!mbedtls_ssl_tls13_key_exchange_mode_with_psk(ssl)) || + handshake->selected_identity != 0 || handshake->ciphersuite_info->id != ssl->session_negotiate->ciphersuite) { @@ -2203,6 +2208,18 @@ static int ssl_tls13_process_encrypted_extensions(mbedtls_ssl_context *ssl) } #endif + /* + * In case the client has proposed a PSK associated with a ticket, + * `ssl->session_negotiate->ciphersuite` still contains at this point the + * identifier of the ciphersuite associated with the ticket. This is that + * way because, if an exchange of early data is agreed upon, we need + * it to check that the ciphersuite selected for the handshake is the + * ticket ciphersuite (see above). This information is not needed + * anymore thus we can now set it to the identifier of the ciphersuite + * used in this session under negotiation. + */ + ssl->session_negotiate->ciphersuite = handshake->ciphersuite_info->id; + MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, buf, buf_len));