[PATCH net 09/11] netfilter: nf_tables: use list_del_rcu for netlink hooks

Pablo Neira Ayuso
2026-04-16T13:15:14Z

From: Florian Westphal <fw@strlen.de>

nft_netdev_unregister_hooks and __nft_unregister_flowtable_net_hooks need
to use list_del_rcu(), this list can be walked by concurrent dumpers.

Add a new helper and use it consistently.

Fixes: f9a43007d3f7 ("netfilter: nf_tables: double hook unregistration in netns path")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/netfilter/nf_tables_api.c | 44 ++++++++++++++---------------------
1 file changed, 18 insertions(+), 26 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 8c42247a176c..090d4d688a33 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -374,6 +374,12 @@ static void nft_netdev_hook_free_rcu(struct nft_hook *hook)
call_rcu(&hook->rcu, __nft_netdev_hook_free_rcu);
}

+static void nft_netdev_hook_unlink_free_rcu(struct nft_hook *hook)
+{
+ list_del_rcu(&hook->list);
+ nft_netdev_hook_free_rcu(hook);
+}
+
static void nft_netdev_unregister_hooks(struct net *net,
struct list_head *hook_list,
bool release_netdev)
@@ -384,10 +390,8 @@ static void nft_netdev_unregister_hooks(struct net *net,
list_for_each_entry_safe(hook, next, hook_list, list) {
list_for_each_entry(ops, &hook->ops_list, list)
nf_unregister_net_hook(net, ops);
- if (release_netdev) {
- list_del(&hook->list);
- nft_netdev_hook_free_rcu(hook);
- }
+ if (release_netdev)
+ nft_netdev_hook_unlink_free_rcu(hook);
}
}

@@ -2323,10 +2327,8 @@ void nf_tables_chain_destroy(struct nft_chain *chain)

if (nft_base_chain_netdev(table->family, basechain->ops.hooknum)) {
list_for_each_entry_safe(hook, next,
- &basechain->hook_list, list) {
- list_del_rcu(&hook->list);
- nft_netdev_hook_free_rcu(hook);
- }
+ &basechain->hook_list, list)
+ nft_netdev_hook_unlink_free_rcu(hook);
}
module_put(basechain->type->owner);
if (rcu_access_pointer(basechain->stats)) {
@@ -3026,6 +3028,7 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
list_for_each_entry(ops, &h->ops_list, list)
nf_unregister_net_hook(ctx->net, ops);
}
+ /* hook.list is on stack, no need for list_del_rcu() */
list_del(&h->list);
nft_netdev_hook_free_rcu(h);
}
@@ -8903,10 +8906,8 @@ static void __nft_unregister_flowtable_net_hooks(struct net *net,
list_for_each_entry_safe(hook, next, hook_list, list) {
list_for_each_entry(ops, &hook->ops_list, list)
nft_unregister_flowtable_ops(net, flowtable, ops);
- if (release_netdev) {
- list_del(&hook->list);
- nft_netdev_hook_free_rcu(hook);
- }
+ if (release_netdev)
+ nft_netdev_hook_unlink_free_rcu(hook);
}
}

@@ -8977,8 +8978,7 @@ static int nft_register_flowtable_net_hooks(struct net *net,

nft_unregister_flowtable_ops(net, flowtable, ops);
}
- list_del_rcu(&hook->list);
- nft_netdev_hook_free_rcu(hook);
+ nft_netdev_hook_unlink_free_rcu(hook);
}

return err;
@@ -8988,10 +8988,8 @@ static void nft_hooks_destroy(struct list_head *hook_list)
{
struct nft_hook *hook, *next;

- list_for_each_entry_safe(hook, next, hook_list, list) {
- list_del_rcu(&hook->list);
- nft_netdev_hook_free_rcu(hook);
- }
+ list_for_each_entry_safe(hook, next, hook_list, list)
+ nft_netdev_hook_unlink_free_rcu(hook);
}

static int nft_flowtable_update(struct nft_ctx *ctx, const struct nlmsghdr *nlh,
@@ -9079,8 +9077,7 @@ static int nft_flowtable_update(struct nft_ctx *ctx, const struct nlmsghdr *nlh,
nft_unregister_flowtable_ops(ctx->net,
flowtable, ops);
}
- list_del_rcu(&hook->list);
- nft_netdev_hook_free_rcu(hook);
+ nft_netdev_hook_unlink_free_rcu(hook);
}

return err;
@@ -9586,13 +9583,8 @@ static void nf_tables_flowtable_notify(struct nft_ctx *ctx,

static void nf_tables_flowtable_destroy(struct nft_flowtable *flowtable)
{
- struct nft_hook *hook, *next;
-
flowtable->data.type->free(&flowtable->data);
- list_for_each_entry_safe(hook, next, &flowtable->hook_list, list) {
- list_del_rcu(&hook->list);
- nft_netdev_hook_free_rcu(hook);
- }
+ nft_hooks_destroy(&flowtable->hook_list);
kfree(flowtable->name);
module_put(flowtable->data.type->owner);
kfree(flowtable);
--
2.47.3