Re: [nf PATCH v3] netfilter: nfnetlink: Fix for interrupted hook dumps

[Pablo Neira Ayuso <pablo@netfilter.org>]

Hi Phil,

On Fri, Sep 04, 2026 at 02:52:15PM +0200, Phil Sutter wrote:
> @@ -338,27 +337,47 @@ nfnl_hook_entries_head(u8 pf, unsigned int hook, struct net *net, const char *de
>  }
>  
>  static int nfnl_hook_dump_nat(struct sk_buff *nlskb,
> -			      const struct nfnl_dump_hook_data *ctx,
> -			      const struct nf_hook_ops *ops,
> -			      int family, unsigned int seq)
> +			      struct netlink_callback *cb,
> +			      const struct nf_hook_ops *ops, int family)
>  {
>  	struct nf_nat_lookup_hook_priv *priv = ops->priv;
> -	struct nf_hook_entries *e = rcu_dereference(priv->entries);
> +	struct nfnl_dump_hook_data *ctx = cb->data;
> +	struct net *net = sock_net(nlskb->sk);
>  	struct nf_hook_ops **nat_ops;
> -	int i, err;
> +	unsigned int i = cb->args[1];
> +	struct nf_hook_entries *e;
> +	unsigned int base_seq;
> +	int err = 0;
>  
> +	base_seq = smp_load_acquire(&net->nf.nat_hook_base_seq);

Maybe annnotate this base sequence in the .start via:

struct netlink_dump_control c = {
        .start = ...;

We should probably start doing this in other nfnetlink subsystems too.

This will help catch an interference between two netlink recv() calls
which results in calling netlink_dump() which calls this function.

Let me know, thanks!