netdev - Re: [PATCH nf-next 2/2] nf_set_hooks_head: acommodate different kconfig

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Date:   Mon, 26 Sep 2016 18:39:20 +0200
From:   Florian Westphal <fw@...len.de>
To:     Aaron Conole <aconole@...heb.org>
Cc:     netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
        Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: Re: [PATCH nf-next 2/2] nf_set_hooks_head: acommodate different
 kconfig

Aaron Conole <aconole@...heb.org> wrote:
> When CONFIG_NETFILTER_INGRESS is unset (or no), we need to handle
> the request for registration properly by dropping the hook.  This
> releases the entry during the set.
> 
> Signed-off-by: Aaron Conole <aconole@...heb.org>
> ---
>  net/netfilter/core.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/net/netfilter/core.c b/net/netfilter/core.c
> index e58e420..1d0a4c9 100644
> --- a/net/netfilter/core.c
> +++ b/net/netfilter/core.c
> @@ -90,10 +90,14 @@ static void nf_set_hooks_head(struct net *net, const struct nf_hook_ops *reg,
>  {
>  	switch (reg->pf) {
>  	case NFPROTO_NETDEV:
> +#ifdef CONFIG_NETFILTER_INGRESS
>  		/* We already checked in nf_register_net_hook() that this is
>  		 * used from ingress.
>  		 */
>  		rcu_assign_pointer(reg->dev->nf_hooks_ingress, entry);
> +#else
> +		kfree(entry);
> +#endif
>  		break;

This looks dodgy (its correct though).

I'd propose to add a test to nf_register_net_hook()
to bail with -EOPNOSTUPP instead of this "#else kfree()" if we get
NFPROTO_NETDEV pf with CONFIG_NETFILTER_INGRESS=n build instead.