Commit df122f58 authored Nov 28, 2016 by Florian Westphal Committed by Pablo Neira Ayuso Dec 06, 2016

netfilter: ingress: translate 0 nf_hook_slow retval to -1



The caller assumes that < 0 means that skb was stolen (or free'd).

All other return values continue skb processing.

nf_hook_slow returns 3 different return value types:

A) a (negative) errno value: the skb was dropped (NF_DROP, e.g.
by iptables '-j DROP' rule).

B) 0. The skb was stolen by the hook or queued to userspace.

C) 1. all hooks returned NF_ACCEPT so the caller should invoke
   the okfn so packet processing can continue.

nft ingress facility currently doesn't have the 'okfn' that
the NF_HOOK() macros use; there is no nfqueue support either.

So 1 means that nf_hook_ingress() caller should go on processing the skb.

In order to allow use of NF_STOLEN from ingress we need to translate
this to an errno number, else we'd crash because we continue with
already-free'd (or about to be free-d) skb.

The errno value isn't checked, its just important that its less than 0,
so return -1.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

parent 1ed9887e

include/linux/netfilter_ingress.h

+6 −1

Original line number	Diff line number	Diff line
		@@ -19,6 +19,7 @@ static inline int nf_hook_ingress(struct sk_buff *skb)
		{
		struct nf_hook_entry *e = rcu_dereference(skb->dev->nf_hooks_ingress);
		struct nf_hook_state state;
		int ret;

		/* Must recheck the ingress hook head, in the event it became NULL
		* after the check in nf_hook_ingress_active evaluated to true.
		@@ -29,7 +30,11 @@ static inline int nf_hook_ingress(struct sk_buff *skb)
		nf_hook_state_init(&state, NF_NETDEV_INGRESS,
		NFPROTO_NETDEV, skb->dev, NULL, NULL,
		dev_net(skb->dev), NULL);
		return nf_hook_slow(skb, &state, e);
		ret = nf_hook_slow(skb, &state, e);
		if (ret == 0)
		return -1;

		return ret;
		}

		static inline void nf_hook_ingress_init(struct net_device *dev)