[NETFILTER]: Move ipv4 specific code from net/core/netfilter.c to net/ipv4/netfilter.c

Netfilter cleanup
- Move ipv4 code from net/core/netfilter.c to net/ipv4/netfilter.c
- Move ipv6 netfilter code from net/ipv6/ip6_output.c to net/ipv6/netfilter.c

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 80 insertions, 1 deletions

diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 55dc6cca1e7b..61c7386bcd2e 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -8,7 +8,7 @@ obj-y     := route.o inetpeer.o protocol.o \
              tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o \
              tcp_minisocks.o tcp_cong.o \
              datagram.o raw.o udp.o arp.o icmp.o devinet.o af_inet.o igmp.o \
-             sysctl_net_ipv4.o fib_frontend.o fib_semantics.o
+             sysctl_net_ipv4.o fib_frontend.o fib_semantics.o netfilter.o
 
 obj-$(CONFIG_IP_FIB_HASH) += fib_hash.o
 obj-$(CONFIG_IP_FIB_TRIE) += fib_trie.o
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 */