On 09/10/2019 15:30, Florian Westphal wrote:
> At this time, NF_HOOK_LIST() macro will iterate the list and then call
> nf_hook() for each skb.
>
> This makes it so the entire list is passed into the netfilter core.
> The advantage is that we only need to fetch the rule blob once per list
> instead of per-skb. If no rules are present, the list operations
> can be elided entirely.
>
> NF_HOOK_LIST only supports ipv4 and ipv6, but those are the only
> callers.
>
> Cc: Edward Cree <ecree@xxxxxxxxxxxxxx>
> Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
> ---
LGTM (but see below).
Acked-by: Edward Cree <ecree@xxxxxxxxxxxxxx>
> include/linux/netfilter.h | 41 +++++++++++++++++++++++++++++----------
> net/netfilter/core.c | 20 +++++++++++++++++++
> 2 files changed, 51 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
> index 77ebb61faf48..eb312e7ca36e 100644
> --- a/include/linux/netfilter.h
> +++ b/include/linux/netfilter.h
> @@ -199,6 +199,8 @@ extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
> int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
> const struct nf_hook_entries *e, unsigned int i);
>
> +void nf_hook_slow_list(struct list_head *head, struct nf_hook_state *state,
> + const struct nf_hook_entries *e);
> /**
> * nf_hook - call a netfilter hook
> *
> @@ -311,17 +313,36 @@ NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
> struct list_head *head, struct net_device *in, struct net_device *out,
> int (*okfn)(struct net *, struct sock *, struct sk_buff *))
> {
> - struct sk_buff *skb, *next;
> - struct list_head sublist;
> -
> - INIT_LIST_HEAD(&sublist);
> - list_for_each_entry_safe(skb, next, head, list) {
> - list_del(&skb->list);
> - if (nf_hook(pf, hook, net, sk, skb, in, out, okfn) == 1)
> - list_add_tail(&skb->list, &sublist);
> + struct nf_hook_entries *hook_head = NULL;
> +
> +#ifdef CONFIG_JUMP_LABEL
> + if (__builtin_constant_p(pf) &&
> + __builtin_constant_p(hook) &&
> + !static_key_false(&nf_hooks_needed[pf][hook]))
> + return;
> +#endif
> +
> + rcu_read_lock();
> + switch (pf) {
> + case NFPROTO_IPV4:
> + hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);
> + break;
> + case NFPROTO_IPV6:
> + hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]);
> + break;
> + default:
> + WARN_ON_ONCE(1);
> + break;
> }
> - /* Put passed packets back on main list */
> - list_splice(&sublist, head);
> +
> + if (hook_head) {
> + struct nf_hook_state state;
> +
> + nf_hook_state_init(&state, hook, pf, in, out, sk, net, okfn);
> +
> + nf_hook_slow_list(head, &state, hook_head);
> + }
> + rcu_read_unlock();
> }
>
> /* Call setsockopt() */
> diff --git a/net/netfilter/core.c b/net/netfilter/core.c
> index 5d5bdf450091..306587b07a4f 100644
> --- a/net/netfilter/core.c
> +++ b/net/netfilter/core.c
> @@ -536,6 +536,26 @@ int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
> }
> EXPORT_SYMBOL(nf_hook_slow);
>
> +void nf_hook_slow_list(struct list_head *head, struct nf_hook_state *state,
> + const struct nf_hook_entries *e)
> +{
> + struct sk_buff *skb, *next;
> + struct list_head sublist;
> + int ret;
> +
> + INIT_LIST_HEAD(&sublist);
> +
> + list_for_each_entry_safe(skb, next, head, list) {
> + list_del(&skb->list);
I know this was just copied from the existing code, but I've been getting
a lot more paranoid lately about skbs escaping with non-NULL ->next
pointers, since several bugs of that kind have turned up elsewhere.
So should this maybe be skb_list_del_init()?
-Ed
> + ret = nf_hook_slow(skb, state, e, 0);
> + if (ret == 1)
> + list_add_tail(&skb->list, &sublist);
> + }
> + /* Put passed packets back on main list */
> + list_splice(&sublist, head);
> +}
> +EXPORT_SYMBOL(nf_hook_slow_list);
> +
> /* This needs to be compiled in any case to avoid dependencies between the
> * nfnetlink_queue code and nf_conntrack.
> */
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