1 files changed, 139 insertions, 0 deletions
diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
new file mode 100644
index 0000000000000..ae0779d82c5d2
--- /dev/null
+++ b/net/ipv4/netfilter.c
@@ -0,0 +1,139 @@
+/* IPv4 specific functions of netfilter core */
+
+#include <linux/config.h>
+#ifdef CONFIG_NETFILTER
+
+#include <linux/kernel.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/icmp.h>
+#include <net/route.h>
+#include <linux/ip.h>
+
+/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
+int ip_route_me_harder(struct sk_buff **pskb)
+{
+	struct iphdr *iph = (*pskb)->nh.iph;
+	struct rtable *rt;
+	struct flowi fl = {};
+	struct dst_entry *odst;
+	unsigned int hh_len;
+
+	/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
+	 * packets with foreign saddr to appear on the NF_IP_LOCAL_OUT hook.
+	 */
+	if (inet_addr_type(iph->saddr) == RTN_LOCAL) {
+		fl.nl_u.ip4_u.daddr = iph->daddr;
+		fl.nl_u.ip4_u.saddr = iph->saddr;
+		fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
+		fl.oif = (*pskb)->sk ? (*pskb)->sk->sk_bound_dev_if : 0;
+#ifdef CONFIG_IP_ROUTE_FWMARK
+		fl.nl_u.ip4_u.fwmark = (*pskb)->nfmark;
+#endif
+		fl.proto = iph->protocol;
+		if (ip_route_output_key(&rt, &fl) != 0)
+			return -1;
+
+		/* Drop old route. */
+		dst_release((*pskb)->dst);
+		(*pskb)->dst = &rt->u.dst;
+	} else {
+		/* non-local src, find valid iif to satisfy
+		 * rp-filter when calling ip_route_input. */
+		fl.nl_u.ip4_u.daddr = iph->saddr;
+		if (ip_route_output_key(&rt, &fl) != 0)
+			return -1;
+
+		odst = (*pskb)->dst;
+		if (ip_route_input(*pskb, iph->daddr, iph->saddr,
+				   RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
+			dst_release(&rt->u.dst);
+			return -1;
+		}
+		dst_release(&rt->u.dst);
+		dst_release(odst);
+	}
+	
+	if ((*pskb)->dst->error)
+		return -1;
+
+	/* Change in oif may mean change in hh_len. */
+	hh_len = (*pskb)->dst->dev->hard_header_len;
+	if (skb_headroom(*pskb) < hh_len) {
+		struct sk_buff *nskb;
+
+		nskb = skb_realloc_headroom(*pskb, hh_len);
+		if (!nskb) 
+			return -1;
+		if ((*pskb)->sk)
+			skb_set_owner_w(nskb, (*pskb)->sk);
+		kfree_skb(*pskb);
+		*pskb = nskb;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(ip_route_me_harder);
+
+/*
+ * Extra routing may needed on local out, as the QUEUE target never
+ * returns control to the table.
+ */
+
+struct ip_rt_info {
+	u_int32_t daddr;
+	u_int32_t saddr;
+	u_int8_t tos;
+};
+
+static void queue_save(const struct sk_buff *skb, struct nf_info *info)
+{
+	struct ip_rt_info *rt_info = nf_info_reroute(info);
+
+	if (info->hook == NF_IP_LOCAL_OUT) {
+		const struct iphdr *iph = skb->nh.iph;
+
+		rt_info->tos = iph->tos;
+		rt_info->daddr = iph->daddr;
+		rt_info->saddr = iph->saddr;
+	}
+}
+
+static int queue_reroute(struct sk_buff **pskb, const struct nf_info *info)
+{
+	const struct ip_rt_info *rt_info = nf_info_reroute(info);
+
+	if (info->hook == NF_IP_LOCAL_OUT) {
+		struct iphdr *iph = (*pskb)->nh.iph;
+
+		if (!(iph->tos == rt_info->tos
+		      && iph->daddr == rt_info->daddr
+		      && iph->saddr == rt_info->saddr))
+			return ip_route_me_harder(pskb);
+	}
+	return 0;
+}
+
+static struct nf_queue_rerouter ip_reroute = {
+	.rer_size	= sizeof(struct ip_rt_info),
+	.save		= queue_save,
+	.reroute	= queue_reroute,
+};
+
+static int init(void)
+{
+	return nf_register_queue_rerouter(PF_INET, &ip_reroute);
+}
+
+static void fini(void)
+{
+	nf_unregister_queue_rerouter(PF_INET);
+}
+
+module_init(init);
+module_exit(fini);
+
+#endif /* CONFIG_NETFILTER */