From df122f58b834b24c27d7e2ac02a4910d3e56f6ae Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 28 Nov 2016 11:40:05 +0100 Subject: [PATCH] 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 Signed-off-by: Pablo Neira Ayuso --- 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..59476061de86 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 (ret == 0) + return -1; + + return ret; } static inline void nf_hook_ingress_init(struct net_device *dev) -- 2.20.1