network: a different implementation of *un*setting firewalld zone when network is destroyed

(this is a remake of commit v10.7.0-78-g200f60b2e1, which was reverted
due to a regression in another patch it was dependent on. The new
implementation just adds the call to virFirewallDInterfaceUnsetZone()
into the existing networkRemoveFirewallRules() (but only if we had set
a zone when the network was first started).

Replaces: 200f60b2e1
Resolves: https://issues.redhat.com/browse/RHEL-61576
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>

src/libvirt_private.syms

@@ -2452,6 +2452,7 @@ virFirewallDGetPolicies;
 virFirewallDGetVersion;
 virFirewallDGetZones;
 virFirewallDInterfaceSetZone;
+virFirewallDInterfaceUnsetZone;
 virFirewallDIsRegistered;
 virFirewallDPolicyExists;
 virFirewallDSynchronize;

src/network/bridge_driver_linux.c

@@ -459,19 +459,37 @@ networkRemoveFirewallRules(virNetworkObj *obj)
     } else {
 
         if ((fw = virNetworkObjGetFwRemoval(obj)) == NULL) {
+
             /* No information about firewall rules in the network status,
              * so we assume the old iptables-based rules from 10.2.0 and
              * earlier.
              */
             VIR_DEBUG("No firewall info in status of network '%s', assuming old-style iptables", def->name);
             iptablesRemoveFirewallRules(def);
-            return;
-        }
 
-        /* fwRemoval info was stored in the network status, so use that to
-         * remove the firewall
-         */
-        VIR_DEBUG("Removing firewall rules of network '%s' using commands saved in status", def->name);
-        virFirewallApply(fw);
+        } else {
+
+            /* fwRemoval info was stored in the network status, so use that to
+             * remove the firewall
+             */
+            VIR_DEBUG("Removing firewall rules of network '%s' using commands saved in status", def->name);
+            virFirewallApply(fw);
+        }
+    }
+
+    /* all forward modes could have had a zone set, even 'open' mode
+     * iff it was specified in the config. firewalld preserves the
+     * name of an interface in a zone's list even after the interface
+     * has been deleted, which is problematic if the next use of that
+     * same interface name wants *no* zone set. To avoid this, we must
+     * "unset" the zone if we set it when the network was started.
+     */
+    if (virFirewallDIsRegistered() == 0 &&
+        (def->forward.type != VIR_NETWORK_FORWARD_OPEN ||
+         def->bridgeZone)) {
+
+        VIR_DEBUG("unsetting zone for '%s' (current zone is '%s')",
+                  def->bridge, def->bridgeZone);
+        virFirewallDInterfaceUnsetZone(def->bridge);
     }
 }

src/util/virfirewalld.c

@@ -449,6 +449,29 @@ virFirewallDInterfaceSetZone(const char *iface,
 }
 
 
+int
+virFirewallDInterfaceUnsetZone(const char *iface)
+{
+    GDBusConnection *sysbus = virGDBusGetSystemBus();
+    g_autoptr(GVariant) message = NULL;
+
+    if (!sysbus)
+        return -1;
+
+    message = g_variant_new("(ss)", "", iface);
+
+    return virGDBusCallMethod(sysbus,
+                              NULL,
+                              NULL,
+                              NULL,
+                              VIR_FIREWALL_FIREWALLD_SERVICE,
+                              "/org/fedoraproject/FirewallD1",
+                              "org.fedoraproject.FirewallD1.zone",
+                              "removeInterface",
+                              message);
+}
+
+
 void
 virFirewallDSynchronize(void)
 {

src/util/virfirewalld.h

@@ -46,4 +46,6 @@ int virFirewallDApplyRule(virFirewallLayer layer,
 int virFirewallDInterfaceSetZone(const char *iface,
                                  const char *zone);
 
+int virFirewallDInterfaceUnsetZone(const char *iface);
+
 void virFirewallDSynchronize(void);