SSL: client certificate validation with OCSP (ticket #1534).

OCSP validation for client certificates is enabled by the "ssl_ocsp" directive.
OCSP responder can be optionally specified by "ssl_ocsp_responder".

When session is reused, peer chain is not available for validation.
If the verified chain contains certificates from the peer chain not available
at the server, validation will fail.

3 files changed, 74 insertions, 5 deletions

diff --git a/src/http/modules/ngx_http_ssl_module.c b/src/http/modules/ngx_http_ssl_module.c
index 495e628d3..1c9accdd3 100644
--- a/src/http/modules/ngx_http_ssl_module.c
+++ b/src/http/modules/ngx_http_ssl_module.c
@@ -74,6 +74,14 @@ static ngx_conf_enum_t  ngx_http_ssl_verify[] = {
 };
 
 
+static ngx_conf_enum_t  ngx_http_ssl_ocsp[] = {
+    { ngx_string("off"), 0 },
+    { ngx_string("on"), 1 },
+    { ngx_string("leaf"), 2 },
+    { ngx_null_string, 0 }
+};
+
+
 static ngx_conf_deprecated_t  ngx_http_ssl_deprecated = {
     ngx_conf_deprecated, "ssl", "listen ... ssl"
 };
@@ -214,6 +222,20 @@ static ngx_command_t  ngx_http_ssl_commands[] = {
       offsetof(ngx_http_ssl_srv_conf_t, crl),
       NULL },
 
+    { ngx_string("ssl_ocsp"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_FLAG,
+      ngx_conf_set_enum_slot,
+      NGX_HTTP_SRV_CONF_OFFSET,
+      offsetof(ngx_http_ssl_srv_conf_t, ocsp),
+      &ngx_http_ssl_ocsp },
+
+    { ngx_string("ssl_ocsp_responder"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
+      ngx_conf_set_str_slot,
+      NGX_HTTP_SRV_CONF_OFFSET,
+      offsetof(ngx_http_ssl_srv_conf_t, ocsp_responder),
+      NULL },
+
     { ngx_string("ssl_stapling"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_FLAG,
       ngx_conf_set_flag_slot,
@@ -561,6 +583,7 @@ ngx_http_ssl_create_srv_conf(ngx_conf_t *cf)
      *     sscf->crl = { 0, NULL };
      *     sscf->ciphers = { 0, NULL };
      *     sscf->shm_zone = NULL;
+     *     sscf->ocsp_responder = { 0, NULL };
      *     sscf->stapling_file = { 0, NULL };
      *     sscf->stapling_responder = { 0, NULL };
      */
@@ -578,6 +601,7 @@ ngx_http_ssl_create_srv_conf(ngx_conf_t *cf)
     sscf->session_timeout = NGX_CONF_UNSET;
     sscf->session_tickets = NGX_CONF_UNSET;
     sscf->session_ticket_keys = NGX_CONF_UNSET_PTR;
+    sscf->ocsp = NGX_CONF_UNSET_UINT;
     sscf->stapling = NGX_CONF_UNSET;
     sscf->stapling_verify = NGX_CONF_UNSET;
 
@@ -641,6 +665,9 @@ ngx_http_ssl_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
 
     ngx_conf_merge_str_value(conf->ciphers, prev->ciphers, NGX_DEFAULT_CIPHERS);
 
+    ngx_conf_merge_uint_value(conf->ocsp, prev->ocsp, 0);
+    ngx_conf_merge_str_value(conf->ocsp_responder, prev->ocsp_responder, "");
+
     ngx_conf_merge_value(conf->stapling, prev->stapling, 0);
     ngx_conf_merge_value(conf->stapling_verify, prev->stapling_verify, 0);
     ngx_conf_merge_str_value(conf->stapling_file, prev->stapling_file, "");
@@ -802,6 +829,22 @@ ngx_http_ssl_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
         return NGX_CONF_ERROR;
     }
 
+    if (conf->ocsp) {
+
+        if (conf->verify == 3) {
+            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
+                          "\"ssl_ocsp\" is incompatible with "
+                          "\"ssl_verify_client optional_no_ca\"");
+            return NGX_CONF_ERROR;
+        }
+
+        if (ngx_ssl_ocsp(cf, &conf->ssl, &conf->ocsp_responder, conf->ocsp)
+            != NGX_OK)
+        {
+            return NGX_CONF_ERROR;
+        }
+    }
+
     if (ngx_ssl_dhparam(cf, &conf->ssl, &conf->dhparam) != NGX_OK) {
         return NGX_CONF_ERROR;
     }
@@ -1118,17 +1161,28 @@ ngx_http_ssl_init(ngx_conf_t *cf)
 
         sscf = cscfp[s]->ctx->srv_conf[ngx_http_ssl_module.ctx_index];
 
-        if (sscf->ssl.ctx == NULL || !sscf->stapling) {
+        if (sscf->ssl.ctx == NULL) {
             continue;
         }
 
         clcf = cscfp[s]->ctx->loc_conf[ngx_http_core_module.ctx_index];
 
-        if (ngx_ssl_stapling_resolver(cf, &sscf->ssl, clcf->resolver,
+        if (sscf->stapling) {
+            if (ngx_ssl_stapling_resolver(cf, &sscf->ssl, clcf->resolver,
+                                          clcf->resolver_timeout)
+                != NGX_OK)
+            {
+                return NGX_ERROR;
+            }
+        }
+
+        if (sscf->ocsp) {
+            if (ngx_ssl_ocsp_resolver(cf, &sscf->ssl, clcf->resolver,
                                       clcf->resolver_timeout)
-            != NGX_OK)
-        {
-            return NGX_ERROR;
+                != NGX_OK)
+            {
+                return NGX_ERROR;
+            }
         }
     }
 
diff --git a/src/http/modules/ngx_http_ssl_module.h b/src/http/modules/ngx_http_ssl_module.h
index 26fdccfe4..92d459f60 100644
--- a/src/http/modules/ngx_http_ssl_module.h
+++ b/src/http/modules/ngx_http_ssl_module.h
@@ -54,6 +54,9 @@ typedef struct {
     ngx_flag_t                      session_tickets;
     ngx_array_t                    *session_ticket_keys;
 
+    ngx_uint_t                      ocsp;
+    ngx_str_t                       ocsp_responder;
+
     ngx_flag_t                      stapling;
     ngx_flag_t                      stapling_verify;
     ngx_str_t                       stapling_file;
diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index eb53996b1..6feb6cc31 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -1993,6 +1993,7 @@ ngx_http_process_request(ngx_http_request_t *r)
     if (r->http_connection->ssl) {
         long                      rc;
         X509                     *cert;
+        const char               *s;
         ngx_http_ssl_srv_conf_t  *sscf;
 
         if (c->ssl == NULL) {
@@ -2037,6 +2038,17 @@ ngx_http_process_request(ngx_http_request_t *r)
 
                 X509_free(cert);
             }
+
+            if (ngx_ssl_ocsp_get_status(c, &s) != NGX_OK) {
+                ngx_log_error(NGX_LOG_INFO, c->log, 0,
+                              "client SSL certificate verify error: %s", s);
+
+                ngx_ssl_remove_cached_session(c->ssl->session_ctx,
+                                       (SSL_get0_session(c->ssl->connection)));
+
+                ngx_http_finalize_request(r, NGX_HTTPS_CERT_ERROR);
+                return;
+            }
         }
     }