Merge tag 'nf-24-11-07' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf

Pablo Neira Ayuso says:

====================
Netfilter fix for net

The following series contains a Netfilter fix:

1) Wait for rcu grace period after netdevice removal is reported via event.

* tag 'nf-24-11-07' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
  netfilter: nf_tables: wait for rcu grace period on net_device removal
====================

Link: https://patch.msgid.link/20241107113212.116634-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

include/net/netfilter/nf_tables.h

@@ -1103,6 +1103,7 @@ struct nft_rule_blob {
  *	@name: name of the chain
  *	@udlen: user data length
  *	@udata: user data in the chain
+ *	@rcu_head: rcu head for deferred release
  *	@blob_next: rule blob pointer to the next in the chain
  */
 struct nft_chain {
@@ -1120,6 +1121,7 @@ struct nft_chain {
 	char				*name;
 	u16				udlen;
 	u8				*udata;
+	struct rcu_head			rcu_head;
 
 	/* Only used during control plane commit phase: */
 	struct nft_rule_blob		*blob_next;
@@ -1263,6 +1265,7 @@ static inline void nft_use_inc_restore(u32 *use)
  *	@sets: sets in the table
  *	@objects: stateful objects in the table
  *	@flowtables: flow tables in the table
+ *	@net: netnamespace this table belongs to
  *	@hgenerator: handle generator state
  *	@handle: table handle
  *	@use: number of chain references to this table
@@ -1282,6 +1285,7 @@ struct nft_table {
 	struct list_head		sets;
 	struct list_head		objects;
 	struct list_head		flowtables;
+	possible_net_t			net;
 	u64				hgenerator;
 	u64				handle;
 	u32				use;

net/netfilter/nf_tables_api.c

@@ -1495,6 +1495,7 @@ static int nf_tables_newtable(struct sk_buff *skb, const struct nfnl_info *info,
 	INIT_LIST_HEAD(&table->sets);
 	INIT_LIST_HEAD(&table->objects);
 	INIT_LIST_HEAD(&table->flowtables);
+	write_pnet(&table->net, net);
 	table->family = family;
 	table->flags = flags;
 	table->handle = ++nft_net->table_handle;
@@ -11430,22 +11431,48 @@ int nft_data_dump(struct sk_buff *skb, int attr, const struct nft_data *data,
 }
 EXPORT_SYMBOL_GPL(nft_data_dump);
 
-int __nft_release_basechain(struct nft_ctx *ctx)
+static void __nft_release_basechain_now(struct nft_ctx *ctx)
 {
 	struct nft_rule *rule, *nr;
 
-	if (WARN_ON(!nft_is_base_chain(ctx->chain)))
-		return 0;
-
-	nf_tables_unregister_hook(ctx->net, ctx->chain->table, ctx->chain);
 	list_for_each_entry_safe(rule, nr, &ctx->chain->rules, list) {
 		list_del(&rule->list);
-		nft_use_dec(&ctx->chain->use);
 		nf_tables_rule_release(ctx, rule);
 	}
+	nf_tables_chain_destroy(ctx->chain);
+}
+
+static void nft_release_basechain_rcu(struct rcu_head *head)
+{
+	struct nft_chain *chain = container_of(head, struct nft_chain, rcu_head);
+	struct nft_ctx ctx = {
+		.family	= chain->table->family,
+		.chain	= chain,
+		.net	= read_pnet(&chain->table->net),
+	};
+
+	__nft_release_basechain_now(&ctx);
+	put_net(ctx.net);
+}
+
+int __nft_release_basechain(struct nft_ctx *ctx)
+{
+	struct nft_rule *rule;
+
+	if (WARN_ON_ONCE(!nft_is_base_chain(ctx->chain)))
+		return 0;
+
+	nf_tables_unregister_hook(ctx->net, ctx->chain->table, ctx->chain);
+	list_for_each_entry(rule, &ctx->chain->rules, list)
+		nft_use_dec(&ctx->chain->use);
+
 	nft_chain_del(ctx->chain);
 	nft_use_dec(&ctx->table->use);
-	nf_tables_chain_destroy(ctx->chain);
+
+	if (maybe_get_net(ctx->net))
+		call_rcu(&ctx->chain->rcu_head, nft_release_basechain_rcu);
+	else
+		__nft_release_basechain_now(ctx);
 
 	return 0;
 }