Send a missing_extension alert if key_share/supported groups not present
Only applies if we're not doing psk.
Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3436)
diff --git a/ssl/statem/extensions_srvr.c b/ssl/statem/extensions_srvr.c
index 0daf7d4..f85477c 100644
--- a/ssl/statem/extensions_srvr.c
+++ b/ssl/statem/extensions_srvr.c
@@ -524,16 +524,23 @@
return 0;
}
- /*
- * Get the clients list of supported curves.
- * TODO(TLS1.3): We should validate that we actually received
- * supported_groups!
- */
+ /* Get the clients list of supported curves. */
if (!tls1_get_curvelist(s, 1, &clntcurves, &clnt_num_curves)) {
*al = SSL_AD_INTERNAL_ERROR;
SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE, ERR_R_INTERNAL_ERROR);
return 0;
}
+ if (clnt_num_curves == 0) {
+ /*
+ * This can only happen if the supported_groups extension was not sent,
+ * because we verify that the length is non-zero when we process that
+ * extension.
+ */
+ *al = SSL_AD_MISSING_EXTENSION;
+ SSLerr(SSL_F_TLS_PARSE_CTOS_KEY_SHARE,
+ SSL_R_MISSING_SUPPORTED_GROUPS_EXTENSION);
+ return 0;
+ }
while (PACKET_remaining(&key_share_list) > 0) {
if (!PACKET_get_net_2(&key_share_list, &group_id)
