1 files changed, 247 insertions, 0 deletions
diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
new file mode 100644
index 00000000..929b27bd
--- /dev/null
+++ b/net/ipv4/netfilter.c
@@ -0,0 +1,247 @@
+/* IPv4 specific functions of netfilter core */
+#include <linux/kernel.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/ip.h>
+#include <linux/skbuff.h>
+#include <linux/gfp.h>
+#include <net/route.h>
+#include <net/xfrm.h>
+#include <net/ip.h>
+#include <net/netfilter/nf_queue.h>
+
+/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
+int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
+{
+	struct net *net = dev_net(skb_dst(skb)->dev);
+	const struct iphdr *iph = ip_hdr(skb);
+	struct rtable *rt;
+	struct flowi4 fl4 = {};
+	__be32 saddr = iph->saddr;
+	__u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
+	unsigned int hh_len;
+
+	if (addr_type == RTN_UNSPEC)
+		addr_type = inet_addr_type(net, saddr);
+	if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
+		flags |= FLOWI_FLAG_ANYSRC;
+	else
+		saddr = 0;
+
+	/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
+	 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
+	 */
+	fl4.daddr = iph->daddr;
+	fl4.saddr = saddr;
+	fl4.flowi4_tos = RT_TOS(iph->tos);
+	fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
+	fl4.flowi4_mark = skb->mark;
+	fl4.flowi4_flags = flags;
+	rt = ip_route_output_key(net, &fl4);
+	if (IS_ERR(rt))
+		return -1;
+
+	/* Drop old route. */
+	skb_dst_drop(skb);
+	skb_dst_set(skb, &rt->dst);
+
+	if (skb_dst(skb)->error)
+		return -1;
+
+#ifdef CONFIG_XFRM
+	if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
+	    xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
+		struct dst_entry *dst = skb_dst(skb);
+		skb_dst_set(skb, NULL);
+		dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0);
+		if (IS_ERR(dst))
+			return -1;
+		skb_dst_set(skb, dst);
+	}
+#endif
+
+	/* Change in oif may mean change in hh_len. */
+	hh_len = skb_dst(skb)->dev->hard_header_len;
+	if (skb_headroom(skb) < hh_len &&
+	    pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
+		return -1;
+
+	return 0;
+}
+EXPORT_SYMBOL(ip_route_me_harder);
+
+#ifdef CONFIG_XFRM
+int ip_xfrm_me_harder(struct sk_buff *skb)
+{
+	struct flowi fl;
+	unsigned int hh_len;
+	struct dst_entry *dst;
+
+	if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
+		return 0;
+	if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
+		return -1;
+
+	dst = skb_dst(skb);
+	if (dst->xfrm)
+		dst = ((struct xfrm_dst *)dst)->route;
+	dst_hold(dst);
+
+	dst = xfrm_lookup(dev_net(dst->dev), dst, &fl, skb->sk, 0);
+	if (IS_ERR(dst))
+		return -1;
+
+	skb_dst_drop(skb);
+	skb_dst_set(skb, dst);
+
+	/* Change in oif may mean change in hh_len. */
+	hh_len = skb_dst(skb)->dev->hard_header_len;
+	if (skb_headroom(skb) < hh_len &&
+	    pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
+		return -1;
+	return 0;
+}
+EXPORT_SYMBOL(ip_xfrm_me_harder);
+#endif
+
+void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
+EXPORT_SYMBOL(ip_nat_decode_session);
+
+/*
+ * Extra routing may needed on local out, as the QUEUE target never
+ * returns control to the table.
+ */
+
+struct ip_rt_info {
+	__be32 daddr;
+	__be32 saddr;
+	u_int8_t tos;
+	u_int32_t mark;
+};
+
+static void nf_ip_saveroute(const struct sk_buff *skb,
+			    struct nf_queue_entry *entry)
+{
+	struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
+
+	if (entry->hook == NF_INET_LOCAL_OUT) {
+		const struct iphdr *iph = ip_hdr(skb);
+
+		rt_info->tos = iph->tos;
+		rt_info->daddr = iph->daddr;
+		rt_info->saddr = iph->saddr;
+		rt_info->mark = skb->mark;
+	}
+}
+
+static int nf_ip_reroute(struct sk_buff *skb,
+			 const struct nf_queue_entry *entry)
+{
+	const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
+
+	if (entry->hook == NF_INET_LOCAL_OUT) {
+		const struct iphdr *iph = ip_hdr(skb);
+
+		if (!(iph->tos == rt_info->tos &&
+		      skb->mark == rt_info->mark &&
+		      iph->daddr == rt_info->daddr &&
+		      iph->saddr == rt_info->saddr))
+			return ip_route_me_harder(skb, RTN_UNSPEC);
+	}
+	return 0;
+}
+
+__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
+			    unsigned int dataoff, u_int8_t protocol)
+{
+	const struct iphdr *iph = ip_hdr(skb);
+	__sum16 csum = 0;
+
+	switch (skb->ip_summed) {
+	case CHECKSUM_COMPLETE:
+		if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
+			break;
+		if ((protocol == 0 && !csum_fold(skb->csum)) ||
+		    !csum_tcpudp_magic(iph->saddr, iph->daddr,
+				       skb->len - dataoff, protocol,
+				       skb->csum)) {
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
+			break;
+		}
+		/* fall through */
+	case CHECKSUM_NONE:
+		if (protocol == 0)
+			skb->csum = 0;
+		else
+			skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
+						       skb->len - dataoff,
+						       protocol, 0);
+		csum = __skb_checksum_complete(skb);
+	}
+	return csum;
+}
+EXPORT_SYMBOL(nf_ip_checksum);
+
+static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
+				      unsigned int dataoff, unsigned int len,
+				      u_int8_t protocol)
+{
+	const struct iphdr *iph = ip_hdr(skb);
+	__sum16 csum = 0;
+
+	switch (skb->ip_summed) {
+	case CHECKSUM_COMPLETE:
+		if (len == skb->len - dataoff)
+			return nf_ip_checksum(skb, hook, dataoff, protocol);
+		/* fall through */
+	case CHECKSUM_NONE:
+		skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
+					       skb->len - dataoff, 0);
+		skb->ip_summed = CHECKSUM_NONE;
+		return __skb_checksum_complete_head(skb, dataoff + len);
+	}
+	return csum;
+}
+
+static int nf_ip_route(struct net *net, struct dst_entry **dst,
+		       struct flowi *fl, bool strict __always_unused)
+{
+	struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
+	if (IS_ERR(rt))
+		return PTR_ERR(rt);
+	*dst = &rt->dst;
+	return 0;
+}
+
+static const struct nf_afinfo nf_ip_afinfo = {
+	.family			= AF_INET,
+	.checksum		= nf_ip_checksum,
+	.checksum_partial	= nf_ip_checksum_partial,
+	.route			= nf_ip_route,
+	.saveroute		= nf_ip_saveroute,
+	.reroute		= nf_ip_reroute,
+	.route_key_size		= sizeof(struct ip_rt_info),
+};
+
+static int ipv4_netfilter_init(void)
+{
+	return nf_register_afinfo(&nf_ip_afinfo);
+}
+
+static void ipv4_netfilter_fini(void)
+{
+	nf_unregister_afinfo(&nf_ip_afinfo);
+}
+
+module_init(ipv4_netfilter_init);
+module_exit(ipv4_netfilter_fini);
+
+#ifdef CONFIG_SYSCTL
+struct ctl_path nf_net_ipv4_netfilter_sysctl_path[] = {
+	{ .procname = "net", },
+	{ .procname = "ipv4", },
+	{ .procname = "netfilter", },
+	{ }
+};
+EXPORT_SYMBOL_GPL(nf_net_ipv4_netfilter_sysctl_path);
+#endif /* CONFIG_SYSCTL */