[nf-next PATCH v4 12/16] netfilter: nf_tables: flowtable: Respect NETDEV_REGISTER events

[Phil Sutter <phil@nwl.cc>]

Hook into new devices if their name matches the hook spec.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
Changes since v3:
- Use list_add_tail_rcu() to avoid breaking readers.
- Return NOTIFY_BAD upon error instead of printing an error message as
  per Florian.
---
 net/netfilter/nf_tables_api.c | 56 +++++++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 13 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index f3b0bc2fe0e3..2684990dd3dc 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9317,23 +9317,49 @@ struct nf_hook_ops *nft_hook_find_ops(const struct nft_hook *hook,
 }
 EXPORT_SYMBOL_GPL(nft_hook_find_ops);
 
-static void nft_flowtable_event(unsigned long event, struct net_device *dev,
-				struct nft_flowtable *flowtable)
+static int nft_flowtable_event(unsigned long event, struct net_device *dev,
+			       struct nft_flowtable *flowtable)
 {
 	struct nf_hook_ops *ops;
 	struct nft_hook *hook;
 
 	list_for_each_entry(hook, &flowtable->hook_list, list) {
-		ops = nft_hook_find_ops(hook, dev);
-		if (!ops)
-			continue;
+		switch (event) {
+		case NETDEV_UNREGISTER:
+			ops = nft_hook_find_ops(hook, dev);
+			if (!ops)
+				continue;
 
-		/* flow_offload_netdev_event() cleans up entries for us. */
-		nft_unregister_flowtable_ops(dev_net(dev), flowtable, ops);
-		list_del_rcu(&ops->list);
-		kfree_rcu(ops, rcu);
-		break;
+			/* flow_offload_netdev_event() cleans up entries for us. */
+			nft_unregister_flowtable_ops(dev_net(dev),
+						     flowtable, ops);
+			list_del_rcu(&ops->list);
+			kfree_rcu(ops, rcu);
+			break;
+		case NETDEV_REGISTER:
+			if (strcmp(hook->ifname, dev->name))
+				continue;
+			ops = kzalloc(sizeof(struct nf_hook_ops),
+				      GFP_KERNEL_ACCOUNT);
+			if (!ops)
+				return 1;
+
+			ops->pf		= NFPROTO_NETDEV;
+			ops->hooknum	= flowtable->hooknum;
+			ops->priority	= flowtable->data.priority;
+			ops->priv	= &flowtable->data;
+			ops->hook	= flowtable->data.type->hook;
+			ops->dev	= dev;
+			if (nft_register_flowtable_ops(dev_net(dev),
+						       flowtable, ops)) {
+				kfree(ops);
+				return 1;
+			}
+			list_add_tail_rcu(&ops->list, &hook->ops_list);
+			break;
+		}
 	}
+	return 0;
 }
 
 static int nf_tables_flowtable_event(struct notifier_block *this,
@@ -9345,15 +9371,19 @@ static int nf_tables_flowtable_event(struct notifier_block *this,
 	struct nft_table *table;
 	struct net *net;
 
-	if (event != NETDEV_UNREGISTER)
-		return 0;
+	if (event != NETDEV_REGISTER &&
+	    event != NETDEV_UNREGISTER)
+		return NOTIFY_DONE;
 
 	net = dev_net(dev);
 	nft_net = nft_pernet(net);
 	mutex_lock(&nft_net->commit_mutex);
 	list_for_each_entry(table, &nft_net->tables, list) {
 		list_for_each_entry(flowtable, &table->flowtables, list) {
-			nft_flowtable_event(event, dev, flowtable);
+			if (nft_flowtable_event(event, dev, flowtable)) {
+				mutex_unlock(&nft_net->commit_mutex);
+				return NOTIFY_BAD;
+			}
 		}
 	}
 	mutex_unlock(&nft_net->commit_mutex);
-- 
2.43.0