[nf-next PATCH v4 11/16] netfilter: nf_tables: chain: 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.
- Use kmemdup() instead of kzalloc() && memcpy() as per Florian.
- Return NOTIFY_BAD upon error instead of printing an error message,
  also suggested by Florian.
---
 net/netfilter/nft_chain_filter.c | 50 +++++++++++++++++++++++++-------
 1 file changed, 39 insertions(+), 11 deletions(-)

diff --git a/net/netfilter/nft_chain_filter.c b/net/netfilter/nft_chain_filter.c
index f8c69d28d656..562af2773a66 100644
--- a/net/netfilter/nft_chain_filter.c
+++ b/net/netfilter/nft_chain_filter.c
@@ -318,23 +318,47 @@ static const struct nft_chain_type nft_chain_filter_netdev = {
 	},
 };
 
-static void nft_netdev_event(unsigned long event, struct net_device *dev,
-			     struct nft_ctx *ctx)
+static int nft_netdev_event(unsigned long event, struct net_device *dev,
+			    struct nft_ctx *ctx)
 {
 	struct nft_base_chain *basechain = nft_base_chain(ctx->chain);
 	struct nf_hook_ops *ops;
 	struct nft_hook *hook;
 
 	list_for_each_entry(hook, &basechain->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;
+
+			if (!(ctx->chain->table->flags & NFT_TABLE_F_DORMANT))
+				nf_unregister_net_hook(ctx->net, ops);
+			list_del_rcu(&ops->list);
+			kfree_rcu(ops, rcu);
+			break;
+		case NETDEV_REGISTER:
+			if (strcmp(hook->ifname, dev->name))
+				continue;
 
-		if (!(ctx->chain->table->flags & NFT_TABLE_F_DORMANT))
-			nf_unregister_net_hook(ctx->net, ops);
-		list_del_rcu(&ops->list);
-		kfree_rcu(ops, rcu);
+			ops = kmemdup(&basechain->ops,
+				      sizeof(struct nf_hook_ops),
+				      GFP_KERNEL_ACCOUNT);
+			if (!ops)
+				return 1;
+
+			ops->dev = dev;
+
+			if (!(ctx->chain->table->flags & NFT_TABLE_F_DORMANT) &&
+			    nf_register_net_hook(dev_net(dev), ops)) {
+				kfree(ops);
+				return 1;
+			}
+			list_add_tail_rcu(&ops->list, &hook->ops_list);
+			break;
+		}
 	}
+	return 0;
 }
 
 static int nf_tables_netdev_event(struct notifier_block *this,
@@ -349,7 +373,8 @@ static int nf_tables_netdev_event(struct notifier_block *this,
 		.net	= dev_net(dev),
 	};
 
-	if (event != NETDEV_UNREGISTER)
+	if (event != NETDEV_REGISTER &&
+	    event != NETDEV_UNREGISTER)
 		return NOTIFY_DONE;
 
 	nft_net = nft_pernet(ctx.net);
@@ -371,7 +396,10 @@ static int nf_tables_netdev_event(struct notifier_block *this,
 				continue;
 
 			ctx.chain = chain;
-			nft_netdev_event(event, dev, &ctx);
+			if (nft_netdev_event(event, dev, &ctx)) {
+				mutex_unlock(&nft_net->commit_mutex);
+				return NOTIFY_BAD;
+			}
 		}
 	}
 	mutex_unlock(&nft_net->commit_mutex);
-- 
2.43.0