On Thu, Oct 13, 2016 at 02:38:21PM +0200, Florian Westphal wrote:
> Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote:
[...]
> > diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
> > index de4fa03f46f3..7040842c34f4 100644
> > --- a/net/ipv4/netfilter/ip_tables.c
> > +++ b/net/ipv4/netfilter/ip_tables.c
> > @@ -29,6 +29,7 @@
> > #include <linux/netfilter/x_tables.h>
> > #include <linux/netfilter_ipv4/ip_tables.h>
> > #include <net/netfilter/nf_log.h>
> > +#include <net/netfilter/nf_queue.h>
> > #include "../../netfilter/xt_repldata.h"
> >
> > MODULE_LICENSE("GPL");
> > @@ -329,6 +330,9 @@ ipt_do_table(struct sk_buff *skb,
> > /* Pop from stack? */
> > if (v != XT_RETURN) {
> > verdict = (unsigned int)(-v) - 1;
> > + if (verdict == NF_QUEUE)
> > + verdict = nf_queue(skb, state,
> > + 0, false);
>
> Any reason why this is needed?
> AFAICS xt_NFQUEUE will never return NF_QUEUE after this patch.
-j QUEUE uses the standard target to return NF_QUEUE. This is very
primitive way to queue packets to userspace queue 0 via nf_queue, but
still may break. I can place this under unlikely() as these days
people should be using NFQUEUE instead.
> > diff --git a/net/netfilter/core.c b/net/netfilter/core.c
> > index 2b3b2f8e39c4..9ae2febd86e3 100644
> > --- a/net/netfilter/core.c
> > +++ b/net/netfilter/core.c
> > @@ -309,6 +309,7 @@ unsigned int nf_iterate(struct sk_buff *skb,
> > unsigned int verdict;
> >
> > while (*entryp) {
> > + RCU_INIT_POINTER(state->hook_entries, *entryp);
> > repeat:
> > verdict = (*entryp)->ops.hook((*entryp)->ops.priv, skb, state);
> > if (verdict != NF_ACCEPT) {
> > @@ -331,9 +332,8 @@ int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state)
> > int ret;
> >
> > entry = rcu_dereference(state->hook_entries);
> > -next_hook:
> > verdict = nf_iterate(skb, state, &entry);
> > - switch (verdict & NF_VERDICT_MASK) {
> > + switch (verdict) {
>
> This looks buggy, verdict might encode errno for NF_DROP case.
>
> What you could do is:
>
> switch (verdict) {
> case NF_ACCEPT:
> /* something */
> break;
> case NF_STOLEN:
> break;
> case NF_DROP: /* fallthrough */
> default: /* drop with error? */
> kfree_skb(skb);
> errno = ...
> }
Right, will fix this, thanks.
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