1 files changed, 309 insertions, 0 deletions

diff --git a/net/netfilter/xt_TEE.c b/net/netfilter/xt_TEE.c
new file mode 100644
index 000000000000..d7920d9f49e9
--- /dev/null
+++ b/net/netfilter/xt_TEE.c
@@ -0,0 +1,309 @@
+/*
+ *	"TEE" target extension for Xtables
+ *	Copyright © Sebastian Claßen, 2007
+ *	Jan Engelhardt, 2007-2010
+ *
+ *	based on ipt_ROUTE.c from Cédric de Launois
+ *	<delaunois@info.ucl.be>
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	version 2 or later, as published by the Free Software Foundation.
+ */
+#include <linux/ip.h>
+#include <linux/module.h>
+#include <linux/percpu.h>
+#include <linux/route.h>
+#include <linux/skbuff.h>
+#include <linux/notifier.h>
+#include <net/checksum.h>
+#include <net/icmp.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <net/ip6_route.h>
+#include <net/route.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_TEE.h>
+
+#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
+#	define WITH_CONNTRACK 1
+#	include <net/netfilter/nf_conntrack.h>
+#endif
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+#	define WITH_IPV6 1
+#endif
+
+struct xt_tee_priv {
+	struct notifier_block	notifier;
+	struct xt_tee_tginfo	*tginfo;
+	int			oif;
+};
+
+static const union nf_inet_addr tee_zero_address;
+static DEFINE_PER_CPU(bool, tee_active);
+
+static struct net *pick_net(struct sk_buff *skb)
+{
+#ifdef CONFIG_NET_NS
+	const struct dst_entry *dst;
+
+	if (skb->dev != NULL)
+		return dev_net(skb->dev);
+	dst = skb_dst(skb);
+	if (dst != NULL && dst->dev != NULL)
+		return dev_net(dst->dev);
+#endif
+	return &init_net;
+}
+
+static bool
+tee_tg_route4(struct sk_buff *skb, const struct xt_tee_tginfo *info)
+{
+	const struct iphdr *iph = ip_hdr(skb);
+	struct net *net = pick_net(skb);
+	struct rtable *rt;
+	struct flowi fl;
+
+	memset(&fl, 0, sizeof(fl));
+	if (info->priv) {
+		if (info->priv->oif == -1)
+			return false;
+		fl.oif = info->priv->oif;
+	}
+	fl.nl_u.ip4_u.daddr = info->gw.ip;
+	fl.nl_u.ip4_u.tos   = RT_TOS(iph->tos);
+	fl.nl_u.ip4_u.scope = RT_SCOPE_UNIVERSE;
+	if (ip_route_output_key(net, &rt, &fl) != 0)
+		return false;
+
+	dst_release(skb_dst(skb));
+	skb_dst_set(skb, &rt->u.dst);
+	skb->dev      = rt->u.dst.dev;
+	skb->protocol = htons(ETH_P_IP);
+	return true;
+}
+
+static unsigned int
+tee_tg4(struct sk_buff *skb, const struct xt_action_param *par)
+{
+	const struct xt_tee_tginfo *info = par->targinfo;
+	struct iphdr *iph;
+
+	if (percpu_read(tee_active))
+		return XT_CONTINUE;
+	/*
+	 * Copy the skb, and route the copy. Will later return %XT_CONTINUE for
+	 * the original skb, which should continue on its way as if nothing has
+	 * happened. The copy should be independently delivered to the TEE
+	 * --gateway.
+	 */
+	skb = pskb_copy(skb, GFP_ATOMIC);
+	if (skb == NULL)
+		return XT_CONTINUE;
+
+#ifdef WITH_CONNTRACK
+	/* Avoid counting cloned packets towards the original connection. */
+	nf_conntrack_put(skb->nfct);
+	skb->nfct     = &nf_conntrack_untracked.ct_general;
+	skb->nfctinfo = IP_CT_NEW;
+	nf_conntrack_get(skb->nfct);
+#endif
+	/*
+	 * If we are in PREROUTING/INPUT, the checksum must be recalculated
+	 * since the length could have changed as a result of defragmentation.
+	 *
+	 * We also decrease the TTL to mitigate potential TEE loops
+	 * between two hosts.
+	 *
+	 * Set %IP_DF so that the original source is notified of a potentially
+	 * decreased MTU on the clone route. IPv6 does this too.
+	 */
+	iph = ip_hdr(skb);
+	iph->frag_off |= htons(IP_DF);
+	if (par->hooknum == NF_INET_PRE_ROUTING ||
+	    par->hooknum == NF_INET_LOCAL_IN)
+		--iph->ttl;
+	ip_send_check(iph);
+
+	if (tee_tg_route4(skb, info)) {
+		percpu_write(tee_active, true);
+		ip_local_out(skb);
+		percpu_write(tee_active, false);
+	} else {
+		kfree_skb(skb);
+	}
+	return XT_CONTINUE;
+}
+
+#ifdef WITH_IPV6
+static bool
+tee_tg_route6(struct sk_buff *skb, const struct xt_tee_tginfo *info)
+{
+	const struct ipv6hdr *iph = ipv6_hdr(skb);
+	struct net *net = pick_net(skb);
+	struct dst_entry *dst;
+	struct flowi fl;
+
+	memset(&fl, 0, sizeof(fl));
+	if (info->priv) {
+		if (info->priv->oif == -1)
+			return false;
+		fl.oif = info->priv->oif;
+	}
+	fl.nl_u.ip6_u.daddr = info->gw.in6;
+	fl.nl_u.ip6_u.flowlabel = ((iph->flow_lbl[0] & 0xF) << 16) |
+				  (iph->flow_lbl[1] << 8) | iph->flow_lbl[2];
+	dst = ip6_route_output(net, NULL, &fl);
+	if (dst == NULL)
+		return false;
+
+	dst_release(skb_dst(skb));
+	skb_dst_set(skb, dst);
+	skb->dev      = dst->dev;
+	skb->protocol = htons(ETH_P_IPV6);
+	return true;
+}
+
+static unsigned int
+tee_tg6(struct sk_buff *skb, const struct xt_action_param *par)
+{
+	const struct xt_tee_tginfo *info = par->targinfo;
+
+	if (percpu_read(tee_active))
+		return XT_CONTINUE;
+	skb = pskb_copy(skb, GFP_ATOMIC);
+	if (skb == NULL)
+		return XT_CONTINUE;
+
+#ifdef WITH_CONNTRACK
+	nf_conntrack_put(skb->nfct);
+	skb->nfct     = &nf_conntrack_untracked.ct_general;
+	skb->nfctinfo = IP_CT_NEW;
+	nf_conntrack_get(skb->nfct);
+#endif
+	if (par->hooknum == NF_INET_PRE_ROUTING ||
+	    par->hooknum == NF_INET_LOCAL_IN) {
+		struct ipv6hdr *iph = ipv6_hdr(skb);
+		--iph->hop_limit;
+	}
+	if (tee_tg_route6(skb, info)) {
+		percpu_write(tee_active, true);
+		ip6_local_out(skb);
+		percpu_write(tee_active, false);
+	} else {
+		kfree_skb(skb);
+	}
+	return XT_CONTINUE;
+}
+#endif /* WITH_IPV6 */
+
+static int tee_netdev_event(struct notifier_block *this, unsigned long event,
+			    void *ptr)
+{
+	struct net_device *dev = ptr;
+	struct xt_tee_priv *priv;
+
+	priv = container_of(this, struct xt_tee_priv, notifier);
+	switch (event) {
+	case NETDEV_REGISTER:
+		if (!strcmp(dev->name, priv->tginfo->oif))
+			priv->oif = dev->ifindex;
+		break;
+	case NETDEV_UNREGISTER:
+		if (dev->ifindex == priv->oif)
+			priv->oif = -1;
+		break;
+	case NETDEV_CHANGENAME:
+		if (!strcmp(dev->name, priv->tginfo->oif))
+			priv->oif = dev->ifindex;
+		else if (dev->ifindex == priv->oif)
+			priv->oif = -1;
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static int tee_tg_check(const struct xt_tgchk_param *par)
+{
+	struct xt_tee_tginfo *info = par->targinfo;
+	struct xt_tee_priv *priv;
+
+	/* 0.0.0.0 and :: not allowed */
+	if (memcmp(&info->gw, &tee_zero_address,
+		   sizeof(tee_zero_address)) == 0)
+		return -EINVAL;
+
+	if (info->oif[0]) {
+		if (info->oif[sizeof(info->oif)-1] != '\0')
+			return -EINVAL;
+
+		priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+		if (priv == NULL)
+			return -ENOMEM;
+
+		priv->tginfo  = info;
+		priv->oif     = -1;
+		priv->notifier.notifier_call = tee_netdev_event;
+		info->priv    = priv;
+
+		register_netdevice_notifier(&priv->notifier);
+	} else
+		info->priv = NULL;
+
+	return 0;
+}
+
+static void tee_tg_destroy(const struct xt_tgdtor_param *par)
+{
+	struct xt_tee_tginfo *info = par->targinfo;
+
+	if (info->priv) {
+		unregister_netdevice_notifier(&info->priv->notifier);
+		kfree(info->priv);
+	}
+}
+
+static struct xt_target tee_tg_reg[] __read_mostly = {
+	{
+		.name       = "TEE",
+		.revision   = 1,
+		.family     = NFPROTO_IPV4,
+		.target     = tee_tg4,
+		.targetsize = sizeof(struct xt_tee_tginfo),
+		.checkentry = tee_tg_check,
+		.destroy    = tee_tg_destroy,
+		.me         = THIS_MODULE,
+	},
+#ifdef WITH_IPV6
+	{
+		.name       = "TEE",
+		.revision   = 1,
+		.family     = NFPROTO_IPV6,
+		.target     = tee_tg6,
+		.targetsize = sizeof(struct xt_tee_tginfo),
+		.checkentry = tee_tg_check,
+		.destroy    = tee_tg_destroy,
+		.me         = THIS_MODULE,
+	},
+#endif
+};
+
+static int __init tee_tg_init(void)
+{
+	return xt_register_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
+}
+
+static void __exit tee_tg_exit(void)
+{
+	xt_unregister_targets(tee_tg_reg, ARRAY_SIZE(tee_tg_reg));
+}
+
+module_init(tee_tg_init);
+module_exit(tee_tg_exit);
+MODULE_AUTHOR("Sebastian Claßen <sebastian.classen@freenet.ag>");
+MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
+MODULE_DESCRIPTION("Xtables: Reroute packet copy");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_TEE");
+MODULE_ALIAS("ip6t_TEE");