From ebb6f7d6563f51ae8325e3c0f10e9c5a91004fda Mon Sep 17 00:00:00 2001 From: Vladimir Homutov Date: Wed, 20 Oct 2021 09:50:02 +0300 Subject: [PATCH] HTTP: connections with wrong ALPN protocols are now rejected. This is a recommended behavior by RFC 7301 and is useful for mitigation of protocol confusion attacks [1]. To avoid possible negative effects, list of supported protocols was extended to include all possible HTTP protocol ALPN IDs registered by IANA [2], i.e. "http/1.0" and "http/0.9". [1] https://alpaca-attack.com/ [2] https://www.iana.org/assignments/tls-extensiontype-values/ --- src/http/modules/ngx_http_ssl_module.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/src/http/modules/ngx_http_ssl_module.c b/src/http/modules/ngx_http_ssl_module.c index 87f038898..c633f3464 100644 --- a/src/http/modules/ngx_http_ssl_module.c +++ b/src/http/modules/ngx_http_ssl_module.c @@ -17,7 +17,7 @@ typedef ngx_int_t (*ngx_ssl_variable_handler_pt)(ngx_connection_t *c, #define NGX_DEFAULT_CIPHERS "HIGH:!aNULL:!MD5" #define NGX_DEFAULT_ECDH_CURVE "auto" -#define NGX_HTTP_ALPN_PROTO "\x08http/1.1" +#define NGX_HTTP_ALPN_PROTOS "\x08http/1.1\x08http/1.0\x08http/0.9" #ifdef TLSEXT_TYPE_application_layer_protocol_negotiation @@ -442,21 +442,20 @@ ngx_http_ssl_alpn_select(ngx_ssl_conn_t *ssl_conn, const unsigned char **out, hc = c->data; if (hc->addr_conf->http2) { - srv = (unsigned char *) NGX_HTTP_V2_ALPN_PROTO NGX_HTTP_ALPN_PROTO; - srvlen = sizeof(NGX_HTTP_V2_ALPN_PROTO NGX_HTTP_ALPN_PROTO) - 1; - + srv = (unsigned char *) NGX_HTTP_V2_ALPN_PROTO NGX_HTTP_ALPN_PROTOS; + srvlen = sizeof(NGX_HTTP_V2_ALPN_PROTO NGX_HTTP_ALPN_PROTOS) - 1; } else #endif { - srv = (unsigned char *) NGX_HTTP_ALPN_PROTO; - srvlen = sizeof(NGX_HTTP_ALPN_PROTO) - 1; + srv = (unsigned char *) NGX_HTTP_ALPN_PROTOS; + srvlen = sizeof(NGX_HTTP_ALPN_PROTOS) - 1; } if (SSL_select_next_proto((unsigned char **) out, outlen, srv, srvlen, in, inlen) != OPENSSL_NPN_NEGOTIATED) { - return SSL_TLSEXT_ERR_NOACK; + return SSL_TLSEXT_ERR_ALERT_FATAL; } ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,