tls13: srv: check tls version in ClientHello with min_tls_version
When server is configured as TLS 1.3 only and receives ClientHello
from a TLS 1.2 only client, it's expected to abort the handshake
instead of downgrading protocol to TLS 1.2 and continuing handshake.
This commit adds a check to make sure server min_tls_version always
larger than received version in ClientHello.
Signed-off-by: Yanray Wang <yanray.wang@arm.com>
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index d983a00..b3f25b5 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -1920,6 +1920,15 @@
* will dispatch to the TLS 1.2 state machine.
*/
if (SSL_CLIENT_HELLO_TLS1_2 == parse_client_hello_ret) {
+ /* Check if server supports TLS 1.2 */
+ if (ssl->conf->min_tls_version > MBEDTLS_SSL_VERSION_TLS1_2) {
+ MBEDTLS_SSL_DEBUG_MSG(
+ 1, ("Unsupported version of TLS 1.2 was received"));
+ MBEDTLS_SSL_PEND_FATAL_ALERT(
+ MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
+ MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
+ return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
+ }
ssl->keep_current_message = 1;
ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_2;
return 0;