1 files changed, 329 insertions, 0 deletions
diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
new file mode 100644
index 0000000..7b39ed4
--- /dev/null
+++ b/net/sched/act_nat.c
@@ -0,0 +1,329 @@
+/*
+ * Stateless NAT actions
+ *
+ * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netfilter.h>
+#include <linux/rtnetlink.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/tc_act/tc_nat.h>
+#include <net/act_api.h>
+#include <net/icmp.h>
+#include <net/ip.h>
+#include <net/netlink.h>
+#include <net/tc_act/tc_nat.h>
+#include <net/tcp.h>
+#include <net/udp.h>
+
+
+#define NAT_TAB_MASK	15
+static struct tcf_common *tcf_nat_ht[NAT_TAB_MASK + 1];
+static u32 nat_idx_gen;
+static DEFINE_RWLOCK(nat_lock);
+
+static struct tcf_hashinfo nat_hash_info = {
+	.htab	=	tcf_nat_ht,
+	.hmask	=	NAT_TAB_MASK,
+	.lock	=	&nat_lock,
+};
+
+static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
+	[TCA_NAT_PARMS]	= { .len = sizeof(struct tc_nat) },
+};
+
+static int tcf_nat_init(struct nlattr *nla, struct nlattr *est,
+			struct tc_action *a, int ovr, int bind)
+{
+	struct nlattr *tb[TCA_NAT_MAX + 1];
+	struct tc_nat *parm;
+	int ret = 0, err;
+	struct tcf_nat *p;
+	struct tcf_common *pc;
+
+	if (nla == NULL)
+		return -EINVAL;
+
+	err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy);
+	if (err < 0)
+		return err;
+
+	if (tb[TCA_NAT_PARMS] == NULL)
+		return -EINVAL;
+	parm = nla_data(tb[TCA_NAT_PARMS]);
+
+	pc = tcf_hash_check(parm->index, a, bind, &nat_hash_info);
+	if (!pc) {
+		pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind,
+				     &nat_idx_gen, &nat_hash_info);
+		if (unlikely(!pc))
+			return -ENOMEM;
+		p = to_tcf_nat(pc);
+		ret = ACT_P_CREATED;
+	} else {
+		p = to_tcf_nat(pc);
+		if (!ovr) {
+			tcf_hash_release(pc, bind, &nat_hash_info);
+			return -EEXIST;
+		}
+	}
+
+	spin_lock_bh(&p->tcf_lock);
+	p->old_addr = parm->old_addr;
+	p->new_addr = parm->new_addr;
+	p->mask = parm->mask;
+	p->flags = parm->flags;
+
+	p->tcf_action = parm->action;
+	spin_unlock_bh(&p->tcf_lock);
+
+	if (ret == ACT_P_CREATED)
+		tcf_hash_insert(pc, &nat_hash_info);
+
+	return ret;
+}
+
+static int tcf_nat_cleanup(struct tc_action *a, int bind)
+{
+	struct tcf_nat *p = a->priv;
+
+	return tcf_hash_release(&p->common, bind, &nat_hash_info);
+}
+
+static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
+		   struct tcf_result *res)
+{
+	struct tcf_nat *p = a->priv;
+	struct iphdr *iph;
+	__be32 old_addr;
+	__be32 new_addr;
+	__be32 mask;
+	__be32 addr;
+	int egress;
+	int action;
+	int ihl;
+
+	spin_lock(&p->tcf_lock);
+
+	p->tcf_tm.lastuse = jiffies;
+	old_addr = p->old_addr;
+	new_addr = p->new_addr;
+	mask = p->mask;
+	egress = p->flags & TCA_NAT_FLAG_EGRESS;
+	action = p->tcf_action;
+
+	p->tcf_bstats.bytes += qdisc_pkt_len(skb);
+	p->tcf_bstats.packets++;
+
+	spin_unlock(&p->tcf_lock);
+
+	if (unlikely(action == TC_ACT_SHOT))
+		goto drop;
+
+	if (!pskb_may_pull(skb, sizeof(*iph)))
+		goto drop;
+
+	iph = ip_hdr(skb);
+
+	if (egress)
+		addr = iph->saddr;
+	else
+		addr = iph->daddr;
+
+	if (!((old_addr ^ addr) & mask)) {
+		if (skb_cloned(skb) &&
+		    !skb_clone_writable(skb, sizeof(*iph)) &&
+		    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+			goto drop;
+
+		new_addr &= mask;
+		new_addr |= addr & ~mask;
+
+		/* Rewrite IP header */
+		iph = ip_hdr(skb);
+		if (egress)
+			iph->saddr = new_addr;
+		else
+			iph->daddr = new_addr;
+
+		csum_replace4(&iph->check, addr, new_addr);
+	}
+
+	ihl = iph->ihl * 4;
+
+	/* It would be nice to share code with stateful NAT. */
+	switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
+	case IPPROTO_TCP:
+	{
+		struct tcphdr *tcph;
+
+		if (!pskb_may_pull(skb, ihl + sizeof(*tcph)) ||
+		    (skb_cloned(skb) &&
+		     !skb_clone_writable(skb, ihl + sizeof(*tcph)) &&
+		     pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+			goto drop;
+
+		tcph = (void *)(skb_network_header(skb) + ihl);
+		inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, 1);
+		break;
+	}
+	case IPPROTO_UDP:
+	{
+		struct udphdr *udph;
+
+		if (!pskb_may_pull(skb, ihl + sizeof(*udph)) ||
+		    (skb_cloned(skb) &&
+		     !skb_clone_writable(skb, ihl + sizeof(*udph)) &&
+		     pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+			goto drop;
+
+		udph = (void *)(skb_network_header(skb) + ihl);
+		if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
+			inet_proto_csum_replace4(&udph->check, skb, addr,
+						 new_addr, 1);
+			if (!udph->check)
+				udph->check = CSUM_MANGLED_0;
+		}
+		break;
+	}
+	case IPPROTO_ICMP:
+	{
+		struct icmphdr *icmph;
+
+		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph)))
+			goto drop;
+
+		icmph = (void *)(skb_network_header(skb) + ihl);
+
+		if ((icmph->type != ICMP_DEST_UNREACH) &&
+		    (icmph->type != ICMP_TIME_EXCEEDED) &&
+		    (icmph->type != ICMP_PARAMETERPROB))
+			break;
+
+		iph = (void *)(icmph + 1);
+		if (egress)
+			addr = iph->daddr;
+		else
+			addr = iph->saddr;
+
+		if ((old_addr ^ addr) & mask)
+			break;
+
+		if (skb_cloned(skb) &&
+		    !skb_clone_writable(skb,
+					ihl + sizeof(*icmph) + sizeof(*iph)) &&
+		    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+			goto drop;
+
+		icmph = (void *)(skb_network_header(skb) + ihl);
+		iph = (void *)(icmph + 1);
+
+		new_addr &= mask;
+		new_addr |= addr & ~mask;
+
+		/* XXX Fix up the inner checksums. */
+		if (egress)
+			iph->daddr = new_addr;
+		else
+			iph->saddr = new_addr;
+
+		inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
+					 1);
+		break;
+	}
+	default:
+		break;
+	}
+
+	return action;
+
+drop:
+	spin_lock(&p->tcf_lock);
+	p->tcf_qstats.drops++;
+	spin_unlock(&p->tcf_lock);
+	return TC_ACT_SHOT;
+}
+
+static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
+			int bind, int ref)
+{
+	unsigned char *b = skb_tail_pointer(skb);
+	struct tcf_nat *p = a->priv;
+	struct tc_nat *opt;
+	struct tcf_t t;
+	int s;
+
+	s = sizeof(*opt);
+
+	/* netlink spinlocks held above us - must use ATOMIC */
+	opt = kzalloc(s, GFP_ATOMIC);
+	if (unlikely(!opt))
+		return -ENOBUFS;
+
+	opt->old_addr = p->old_addr;
+	opt->new_addr = p->new_addr;
+	opt->mask = p->mask;
+	opt->flags = p->flags;
+
+	opt->index = p->tcf_index;
+	opt->action = p->tcf_action;
+	opt->refcnt = p->tcf_refcnt - ref;
+	opt->bindcnt = p->tcf_bindcnt - bind;
+
+	NLA_PUT(skb, TCA_NAT_PARMS, s, opt);
+	t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
+	t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
+	t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
+	NLA_PUT(skb, TCA_NAT_TM, sizeof(t), &t);
+
+	kfree(opt);
+
+	return skb->len;
+
+nla_put_failure:
+	nlmsg_trim(skb, b);
+	kfree(opt);
+	return -1;
+}
+
+static struct tc_action_ops act_nat_ops = {
+	.kind		=	"nat",
+	.hinfo		=	&nat_hash_info,
+	.type		=	TCA_ACT_NAT,
+	.capab		=	TCA_CAP_NONE,
+	.owner		=	THIS_MODULE,
+	.act		=	tcf_nat,
+	.dump		=	tcf_nat_dump,
+	.cleanup	=	tcf_nat_cleanup,
+	.lookup		=	tcf_hash_search,
+	.init		=	tcf_nat_init,
+	.walk		=	tcf_generic_walker
+};
+
+MODULE_DESCRIPTION("Stateless NAT actions");
+MODULE_LICENSE("GPL");
+
+static int __init nat_init_module(void)
+{
+	return tcf_register_action(&act_nat_ops);
+}
+
+static void __exit nat_cleanup_module(void)
+{
+	tcf_unregister_action(&act_nat_ops);
+}
+
+module_init(nat_init_module);
+module_exit(nat_cleanup_module);