Separate accepting TLS 1.3 middlebox compatibility from sending it
The compile-time option MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE gates both
support for interoperability with a peer that uses middlebox compatibility
mode, and support for activating that mode ourselves. Change code that is
only needed for interoperability to be guarded by
MBEDTLS_SSL_TLS1_3_ACCEPT_COMPATIBILITY_MODE.
As of this commit, MBEDTLS_SSL_TLS1_3_ACCEPT_COMPATIBILITY_MODE is always
enabled: there is no way to disable it, and there are no tests with it
disabled.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index 47e56e8..23d7b22 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -65,6 +65,13 @@
/* Faked handshake message identity for HelloRetryRequest. */
#define MBEDTLS_SSL_TLS1_3_HS_HELLO_RETRY_REQUEST (-MBEDTLS_SSL_HS_SERVER_HELLO)
+/* TLS 1.3: Interoperate with peers that support middlebox compatibility
+ * mode, but don't produce the relevant messages ourselves.
+ *
+ * This is always enabled (with effect only when TLS 1.3 is enabled).
+ */
+#define MBEDTLS_SSL_TLS1_3_ACCEPT_COMPATIBILITY_MODE
+
/*
* Internal identity of handshake extensions
*/
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 2bdad84..86463bc 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -5066,7 +5066,7 @@
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
-#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
+#if defined(MBEDTLS_SSL_TLS1_3_ACCEPT_COMPATIBILITY_MODE)
MBEDTLS_SSL_DEBUG_MSG(1,
("Ignore ChangeCipherSpec in TLS 1.3 compatibility mode"));
return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
@@ -5074,7 +5074,7 @@
MBEDTLS_SSL_DEBUG_MSG(1,
("ChangeCipherSpec invalid in TLS 1.3 without compatibility mode"));
return MBEDTLS_ERR_SSL_INVALID_RECORD;
-#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
+#endif /* MBEDTLS_SSL_TLS1_3_ACCEPT_COMPATIBILITY_MODE */
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
}