[libvirt] [PATCH v3 13/20] conf: report an error if nic needs filtering by no driver is present

[Daniel P. Berrangé]

If a <interface> includes a filter name but the nwfilter driver is not
present we silently do nothing. This is very bad, because an application
that thinks it is protected by malicious guest traffic will in fact be
vulnerable. Reporting an error gives the administrator the ability to
know there is a problem and fix it.

Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
---
 src/conf/domain_nwfilter.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/conf/domain_nwfilter.c b/src/conf/domain_nwfilter.c
index e360aceeba..7570e0ae83 100644
--- a/src/conf/domain_nwfilter.c
+++ b/src/conf/domain_nwfilter.c
@@ -28,6 +28,9 @@
 #include "datatypes.h"
 #include "domain_conf.h"
 #include "domain_nwfilter.h"
+#include "virerror.h"
+
+#define VIR_FROM_THIS VIR_FROM_NWFILTER
 
 static virDomainConfNWFilterDriverPtr nwfilterDriver;
 
@@ -44,8 +47,10 @@ virDomainConfNWFilterInstantiate(const char *vmname,
 {
     if (nwfilterDriver != NULL)
         return nwfilterDriver->instantiateFilter(vmname, vmuuid, net);
-    /* driver module not available -- don't indicate failure */
-    return 0;
+
+    virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                   _("No network filter driver available"));
+    return -1;
 }
 
 void
-- 
2.17.0