Subject: Re: [resend] Passive OS fingerprint xtables match.

From: Evgeniy Polyakov <[email-masked]>
Date: Thu, 4 Jun 2009 17:11:53 +0400

On Thu, Jun 04, 2009 at 02:11:24PM +0200, Patrick McHardy ([email-masked]) wrote:
> Thats not what I meant. struct xt_match_param is passed to the
> ->match() callbacks from *t_do_table(). This is where you can
> add the real hook number to have it available in ->match().
> 
> (Forgot to mention earlier: please in a seperate patch and adjusting
>  all *tables copies)

Kind of this (for ipv4 only so far, also reorderd a field to fill the
gap):

diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index 7b1a652..65a08ae 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -184,9 +184,10 @@ struct xt_counters_info
  * @matchinfo:	per-match data
  * @fragoff:	packet is a fragment, this is the data offset
  * @thoff:	position of transport header relative to skb->data
- * @hotdrop:	drop packet if we had inspection problems
+ * @hook:	hook number given packet came from
  * @family:	Actual NFPROTO_* through which the function is invoked
  * 		(helpful when match->family == NFPROTO_UNSPEC)
+ * @hotdrop:	drop packet if we had inspection problems
  */
 struct xt_match_param {
 	const struct net_device *in, *out;
@@ -194,8 +195,9 @@ struct xt_match_param {
 	const void *matchinfo;
 	int fragoff;
 	unsigned int thoff;
-	bool *hotdrop;
+	unsigned int hooknum;
 	u_int8_t family;
+	bool *hotdrop;
 };
 
 /**
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 810c0b6..385e4a0 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -335,7 +335,7 @@ ipt_do_table(struct sk_buff *skb,
 	mtpar.in      = tgpar.in  = in;
 	mtpar.out     = tgpar.out = out;
 	mtpar.family  = tgpar.family = NFPROTO_IPV4;
-	tgpar.hooknum = hook;
+	mtpar.hooknum = tgpar.hooknum = hook;
 
 	IP_NF_ASSERT(table->valid_hooks & (1 << hook));

-- 
	Evgeniy Polyakov