1 files changed, 79 insertions, 0 deletions
diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
new file mode 100644
index 000000000000..6594d1c9697e
--- /dev/null
+++ b/net/ipv4/netfilter.c
@@ -0,0 +1,79 @@
+#include <linux/config.h>
+
+#ifdef CONFIG_NETFILTER
+
+/* IPv4 specific functions of netfilter core */
+#include <linux/kernel.h>
+#include <linux/netfilter.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);
+#endif /* CONFIG_NETFILTER */