SSL: the "ssl_verify_client" directive parameter "optional_no_ca".

This parameter allows to don't require certificate to be signed by
a trusted CA, e.g. if CA certificate isn't known in advance, like in
WebID protocol.

Note that it doesn't add any security unless the certificate is actually
checked to be trusted by some external means (e.g. by a backend).

Patch by Mike Kazantsev, Eric O'Connor.

2 files changed, 5 insertions, 2 deletions

diff --git a/src/http/modules/ngx_http_ssl_module.c b/src/http/modules/ngx_http_ssl_module.c
index 0073dba3c..284edd002 100644
--- a/src/http/modules/ngx_http_ssl_module.c
+++ b/src/http/modules/ngx_http_ssl_module.c
@@ -50,6 +50,7 @@ static ngx_conf_enum_t  ngx_http_ssl_verify[] = {
     { ngx_string("off"), 0 },
     { ngx_string("on"), 1 },
     { ngx_string("optional"), 2 },
+    { ngx_string("optional_no_ca"), 3 },
     { ngx_null_string, 0 }
 };
 
@@ -515,7 +516,7 @@ ngx_http_ssl_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
 
     if (conf->verify) {
 
-        if (conf->client_certificate.len == 0) {
+        if (conf->client_certificate.len == 0 && conf->verify != 3) {
             ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                           "no ssl_client_certificate for ssl_client_verify");
             return NGX_CONF_ERROR;
diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index cb970c5c2..ec9d4a1c3 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -1642,7 +1642,9 @@ ngx_http_process_request(ngx_http_request_t *r)
         if (sscf->verify) {
             rc = SSL_get_verify_result(c->ssl->connection);
 
-            if (rc != X509_V_OK) {
+            if (rc != X509_V_OK
+                && (sscf->verify != 3 || !ngx_ssl_verify_error_optional(rc)))
+            {
                 ngx_log_error(NGX_LOG_INFO, c->log, 0,
                               "client SSL certificate verify error: (%l:%s)",
                               rc, X509_verify_cert_error_string(rc));