nl_bridge: flush our fdb entries on vlan removal

meson.build

@@ -29,6 +29,7 @@ sources = files('''
   src/netlink/nl_hashing.h
   src/netlink/nl_interface.cc
   src/netlink/nl_interface.h
+  src/netlink/nl_fdb_flush.h
   src/netlink/nl_l3.cc
   src/netlink/nl_l3.h
   src/netlink/nl_l3_interfaces.h

src/netlink/nl_bridge.cc

@@ -25,6 +25,7 @@
 #include "cnetlink.h"
 #include "netlink-utils.h"
 #include "nl_bridge.h"
+#include "nl_fdb_flush.h"
 #include "nl_output.h"
 #include "nl_vlan.h"
 #include "nl_vxlan.h"
@@ -485,6 +486,15 @@ void nl_bridge::update_vlans(rtnl_link *old_link, rtnl_link *new_link) {
 
           // the PVID is already being handled outside of the loop
           vlan->remove_bridge_vlan(_link, vid, false, !egress_untagged);
+
+          // remove all fdb entries by us
+          nl_fdb_flush ff;
+
+          auto ret = ff.flush_fdb(rtnl_link_get_ifindex(_link), vid,
+                                  NTF_MASTER | NTF_EXT_LEARNED);
+          if (ret < 0)
+            LOG(WARNING) << __FUNCTION__ << ": failed to flush vid=" << vid
+                         << " on port " << _link;
         }
       }
     }
@@ -781,13 +791,20 @@ void nl_bridge::remove_neigh_from_fdb(rtnl_neigh *neigh) {
     return;
   }
 
-  // lookup l2_cache as well
-  std::unique_ptr<rtnl_neigh, decltype(&rtnl_neigh_put)> n_lookup(
-      NEIGH_CAST(nl_cache_search(l2_cache.get(), OBJ_CAST(neigh))),
-      rtnl_neigh_put);
+  if ((rtnl_neigh_get_flags(neigh) & NTF_EXT_LEARNED) == NTF_EXT_LEARNED) {
+    // lookup l2_cache as well
+    std::unique_ptr<rtnl_neigh, decltype(&rtnl_neigh_put)> n_lookup(
+        NEIGH_CAST(nl_cache_search(l2_cache.get(), OBJ_CAST(neigh))),
+        rtnl_neigh_put);
 
-  if (n_lookup) {
-    nl_cache_remove(OBJ_CAST(n_lookup.get()));
+    if (n_lookup) {
+      nl_cache_remove(OBJ_CAST(n_lookup.get()));
+    } else {
+      // if we flushed the entry, we already removed it from cache and flows, so
+      // no need to do anything here
+      VLOG(2) << __FUNCTION__ << ": neigh not found in cache" << neigh;
+      return;
+    }
   }
 
   const uint32_t port = nl->get_port_id(rtnl_neigh_get_ifindex(neigh));

src/netlink/nl_fdb_flush.h

@@ -0,0 +1,79 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#pragma once
+
+#include <cassert>
+#include <chrono>
+#include <future>
+#include <iostream>
+#include <thread>
+
+#include <glog/logging.h>
+
+#include <netlink/attr.h>
+#include <linux/rtnetlink.h>
+
+#include "nl_output.h"
+
+namespace basebox {
+
+class nl_fdb_flush final {
+  struct nl_sock *sock;
+
+public:
+  nl_fdb_flush() {
+    sock = nl_socket_alloc();
+    int err;
+    if ((err = nl_connect(sock, NETLINK_ROUTE)) < 0)
+      LOG(FATAL) << __FUNCTION__ << ": Unable to connect netlink socket: %s"
+                 << nl_geterror(err);
+  }
+
+  ~nl_fdb_flush() { nl_socket_free(sock); }
+
+  /**
+   * flush fdb
+   */
+  int flush_fdb(int ifindex, uint16_t vlan, uint8_t flags) {
+    struct nl_msg *m;
+    struct ndmsg ndm;
+    int err;
+
+    memset(&ndm, 0, sizeof(ndm));
+    ndm.ndm_family = PF_BRIDGE;
+    ndm.ndm_ifindex = ifindex;
+    ndm.ndm_flags = flags;
+
+    m = nlmsg_alloc_simple(RTM_DELNEIGH, NLM_F_REQUEST | NLM_F_BULK);
+    if (!m)
+      LOG(FATAL) << __FUNCTION__ << ": out of memory";
+
+    if (nlmsg_append(m, &ndm, sizeof(ndm), NLMSG_ALIGNTO) < 0)
+      LOG(FATAL) << __FUNCTION__ << ": out of memory";
+
+    if (vlan > 0) {
+      if (nla_put_u16(m, NDA_VLAN, vlan) < 0)
+        LOG(FATAL) << __FUNCTION__ << ": out of memory";
+    }
+
+    if (flags > 0) {
+      if (nla_put_u8(m, NDA_NDM_FLAGS_MASK, flags) < 0)
+        LOG(FATAL) << __FUNCTION__ << ": out of memory";
+    }
+
+    err = nl_send_auto_complete(sock, m);
+    nlmsg_free(m);
+    if (err < 0)
+      LOG(FATAL) << __FUNCTION__ << ": " << nl_geterror(err);
+
+    if ((err = nl_recvmsgs_default(sock)) < 0) {
+      LOG(FATAL) << __FUNCTION__ << ": " << nl_geterror(err);
+    }
+
+    return 0;
+  }
+};
+
+} // namespace basebox