netfilter: x_tables: Pass struct net in xt_action_param

As xt_action_param lives on the stack this does not bloat any
persistent data structures.

This is a first step in making netfilter code that needs to know
which network namespace it is executing in simpler.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/linux/netfilter/x_tables.h

@@ -13,6 +13,7 @@
  * @target:	the target extension
  * @matchinfo:	per-match data
  * @targetinfo:	per-target data
+ * @net		network namespace through which the action was invoked
  * @in:		input netdevice
  * @out:	output netdevice
  * @fragoff:	packet is a fragment, this is the data offset
@@ -24,7 +25,6 @@
  * Fields written to by extensions:
  *
  * @hotdrop:	drop packet if we had inspection problems
- * Network namespace obtainable using dev_net(in/out)
  */
 struct xt_action_param {
 	union {
@@ -34,6 +34,7 @@ struct xt_action_param {
 	union {
 		const void *matchinfo, *targinfo;
 	};
+	struct net *net;
 	const struct net_device *in, *out;
 	int fragoff;
 	unsigned int thoff;

include/net/netfilter/nf_tables.h

@@ -30,6 +30,7 @@ static inline void nft_set_pktinfo(struct nft_pktinfo *pkt,
 				   const struct nf_hook_state *state)
 {
 	pkt->skb = skb;
+	pkt->xt.net = state->net;
 	pkt->in = pkt->xt.in = state->in;
 	pkt->out = pkt->xt.out = state->out;
 	pkt->hook = pkt->xt.hooknum = state->hook;

net/bridge/netfilter/ebtables.c

@@ -200,6 +200,7 @@ unsigned int ebt_do_table(struct sk_buff *skb,
 	struct xt_action_param acpar;
 
 	acpar.family  = NFPROTO_BRIDGE;
+	acpar.net     = state->net;
 	acpar.in      = state->in;
 	acpar.out     = state->out;
 	acpar.hotdrop = false;

net/ipv4/netfilter/arp_tables.c

@@ -285,6 +285,7 @@ unsigned int arpt_do_table(struct sk_buff *skb,
 	 */
 	e = get_entry(table_base, private->hook_entry[hook]);
 
+	acpar.net     = state->net;
 	acpar.in      = state->in;
 	acpar.out     = state->out;
 	acpar.hooknum = hook;

net/ipv4/netfilter/ip_tables.c

@@ -315,6 +315,7 @@ ipt_do_table(struct sk_buff *skb,
 	acpar.fragoff = ntohs(ip->frag_off) & IP_OFFSET;
 	acpar.thoff   = ip_hdrlen(skb);
 	acpar.hotdrop = false;
+	acpar.net     = state->net;
 	acpar.in      = state->in;
 	acpar.out     = state->out;
 	acpar.family  = NFPROTO_IPV4;

net/ipv6/netfilter/ip6_tables.c

@@ -340,6 +340,7 @@ ip6t_do_table(struct sk_buff *skb,
 	 * rule is also a fragment-specific rule, non-fragments won't
 	 * match it. */
 	acpar.hotdrop = false;
+	acpar.net     = state->net;
 	acpar.in      = state->in;
 	acpar.out     = state->out;
 	acpar.family  = NFPROTO_IPV6;

net/sched/act_ipt.c

@@ -189,6 +189,7 @@ static int tcf_ipt(struct sk_buff *skb, const struct tc_action *a,
 	 * worry later - danger - this API seems to have changed
 	 * from earlier kernels
 	 */
+	par.net	     = dev_net(skb->dev);
 	par.in       = skb->dev;
 	par.out      = NULL;
 	par.hooknum  = ipt->tcfi_hook;

net/sched/em_ipset.c

@@ -95,6 +95,7 @@ static int em_ipset_match(struct sk_buff *skb, struct tcf_ematch *em,
 	if (skb->skb_iif)
 		indev = dev_get_by_index_rcu(em->net, skb->skb_iif);
 
+	acpar.net     = em->net;
 	acpar.in      = indev ? indev : dev;
 	acpar.out     = dev;