| Message ID | 1480329606-6592-2-git-send-email-fw@strlen.de |
|---|---|
| State | Accepted |
| Delegated to: | Pablo Neira |
| Headers | show |
On Mon, Nov 28, 2016 at 11:40:05AM +0100, Florian Westphal wrote: > 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. Not really comments to block anything, so take them lightly. Probably we can just set this to -1, I know this maps to some errno value, but at least from code reading it will be make think that we meant to return EINPROGRESS. If you agree, I can just mangle the patch. One more question below. > Signed-off-by: Florian Westphal <fw@strlen.de> > --- > 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; Do you prefer to keep this branch as unlikely? I understand most people are not using fwd much so far, but we're targeting to enrich ingress so I would expect users will be using this more and more. Anyway, we can revisit this later on. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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)
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@strlen.de> --- include/linux/netfilter_ingress.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)