SSL: SSL_sendfile() support with kernel TLS. Requires OpenSSL 3.0 compiled with "enable-ktls" option. Further, KTLS needs to be enabled in kernel, and in OpenSSL, either via OpenSSL configuration file or with "ssl_conf_command Options KTLS;" in nginx configuration. On FreeBSD, kernel TLS is available starting with FreeBSD 13.0, and can be enabled with "sysctl kern.ipc.tls.enable=1" and "kldload ktls_ocf" to load a software backend, see man ktls(4) for details. On Linux, kernel TLS is available starting with kernel 4.13 (at least 5.2 is recommended), and needs kernel compiled with CONFIG_TLS=y (with CONFIG_TLS=m, which is used at least on Ubuntu 21.04 by default, the tls module needs to be loaded with "modprobe tls").

--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -607,7 +607,7 @@ ngx_http_alloc_request(ngx_connection_t 
     }
 
 #if (NGX_HTTP_SSL)
-    if (c->ssl) {
+    if (c->ssl && !c->ssl->sendfile) {
         r->main_filter_need_in_memory = 1;
     }
 #endif