netfilter: refactor NAT redirect IPv4 to use it from nf_tables

This patch refactors the IPv4 code so it can be usable both from xt and
nf_tables.

A similar patch follows-up to handle IPv6.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 3 insertions, 42 deletions

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index ae5096ab65eb..a0716a3f08b0 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -835,6 +835,7 @@ config NETFILTER_XT_TARGET_RATEEST
 config NETFILTER_XT_TARGET_REDIRECT
         tristate "REDIRECT target support"
         depends on NF_NAT
+        select NF_NAT_REDIRECT_IPV4
         ---help---
         REDIRECT is a special case of NAT: all incoming connections are
         mapped onto the incoming interface's address, causing the packets to
diff --git a/net/netfilter/xt_REDIRECT.c b/net/netfilter/xt_REDIRECT.c
index 22a10309297c..b4ffac5fe8e9 100644
--- a/net/netfilter/xt_REDIRECT.c
+++ b/net/netfilter/xt_REDIRECT.c
@@ -26,6 +26,7 @@
 #include <net/checksum.h>
 #include <net/protocol.h>
 #include <net/netfilter/nf_nat.h>
+#include <net/netfilter/ipv4/nf_nat_redirect.h>
 
 static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
 
@@ -98,48 +99,7 @@ static int redirect_tg4_check(const struct xt_tgchk_param *par)
 static unsigned int
 redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par)
 {
-        struct nf_conn *ct;
-        enum ip_conntrack_info ctinfo;
-        __be32 newdst;
-        const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
-        struct nf_nat_range newrange;
-
-        NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
-                     par->hooknum == NF_INET_LOCAL_OUT);
-
-        ct = nf_ct_get(skb, &ctinfo);
-        NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
-
-        /* Local packets: make them go to loopback */
-        if (par->hooknum == NF_INET_LOCAL_OUT)
-                newdst = htonl(0x7F000001);
-        else {
-                struct in_device *indev;
-                struct in_ifaddr *ifa;
-
-                newdst = 0;
-
-                rcu_read_lock();
-                indev = __in_dev_get_rcu(skb->dev);
-                if (indev && (ifa = indev->ifa_list))
-                        newdst = ifa->ifa_local;
-                rcu_read_unlock();
-
-                if (!newdst)
-                        return NF_DROP;
-        }
-
-        /* Transfer from original range. */
-        memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
-        memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
-        newrange.flags       = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
-        newrange.min_addr.ip = newdst;
-        newrange.max_addr.ip = newdst;
-        newrange.min_proto   = mr->range[0].min;
-        newrange.max_proto   = mr->range[0].max;
-
-        /* Hand modified range to generic setup. */
-        return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
+        return nf_nat_redirect_ipv4(skb, par->targinfo, par->hooknum);
 }
 
 static struct xt_target redirect_tg_reg[] __read_mostly = {