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.
Random dice roll has chosen EINPROGRESS. The errno value isn't checked,
its just important that its less than 0.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
include/linux/netfilter_ingress.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/include/linux/netfilter_ingress.h b/include/linux/netfilter_ingress.h
index 2dc3b49b804a..d5027e470a24 100644
--- a/include/linux/netfilter_ingress.h
+++ b/include/linux/netfilter_ingress.h
@@ -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 (unlikely(ret == 0))
+ return -EINPROGRESS;
+
+ return ret;
}
static inline void nf_hook_ingress_init(struct net_device *dev)
--
2.7.3
--
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