[NETFILTER]: Add NAT support for nf_conntrack
Add NAT support for nf_conntrack. Joint work of Jozsef Kadlecsik,
Yasuyuki Kozakai, Martin Josefsson and myself.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter/nf_nat_rule.c b/net/ipv4/netfilter/nf_nat_rule.c
new file mode 100644
index 0000000..b868ee0
--- /dev/null
+++ b/net/ipv4/netfilter/nf_nat_rule.c
@@ -0,0 +1,343 @@
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/* Everything about the rules for NAT. */
+#include <linux/types.h>
+#include <linux/ip.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/module.h>
+#include <linux/kmod.h>
+#include <linux/skbuff.h>
+#include <linux/proc_fs.h>
+#include <net/checksum.h>
+#include <net/route.h>
+#include <linux/bitops.h>
+
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_core.h>
+#include <net/netfilter/nf_nat_rule.h>
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+#define NAT_VALID_HOOKS ((1<<NF_IP_PRE_ROUTING) | (1<<NF_IP_POST_ROUTING) | (1<<NF_IP_LOCAL_OUT))
+
+static struct
+{
+ struct ipt_replace repl;
+ struct ipt_standard entries[3];
+ struct ipt_error term;
+} nat_initial_table __initdata = {
+ .repl = {
+ .name = "nat",
+ .valid_hooks = NAT_VALID_HOOKS,
+ .num_entries = 4,
+ .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
+ .hook_entry = {
+ [NF_IP_PRE_ROUTING] = 0,
+ [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
+ [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 },
+ .underflow = {
+ [NF_IP_PRE_ROUTING] = 0,
+ [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard),
+ [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 },
+ },
+ .entries = {
+ /* PRE_ROUTING */
+ {
+ .entry = {
+ .target_offset = sizeof(struct ipt_entry),
+ .next_offset = sizeof(struct ipt_standard),
+ },
+ .target = {
+ .target = {
+ .u = {
+ .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)),
+ },
+ },
+ .verdict = -NF_ACCEPT - 1,
+ },
+ },
+ /* POST_ROUTING */
+ {
+ .entry = {
+ .target_offset = sizeof(struct ipt_entry),
+ .next_offset = sizeof(struct ipt_standard),
+ },
+ .target = {
+ .target = {
+ .u = {
+ .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)),
+ },
+ },
+ .verdict = -NF_ACCEPT - 1,
+ },
+ },
+ /* LOCAL_OUT */
+ {
+ .entry = {
+ .target_offset = sizeof(struct ipt_entry),
+ .next_offset = sizeof(struct ipt_standard),
+ },
+ .target = {
+ .target = {
+ .u = {
+ .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)),
+ },
+ },
+ .verdict = -NF_ACCEPT - 1,
+ },
+ },
+ },
+ /* ERROR */
+ .term = {
+ .entry = {
+ .target_offset = sizeof(struct ipt_entry),
+ .next_offset = sizeof(struct ipt_error),
+ },
+ .target = {
+ .target = {
+ .u = {
+ .user = {
+ .target_size = IPT_ALIGN(sizeof(struct ipt_error_target)),
+ .name = IPT_ERROR_TARGET,
+ },
+ },
+ },
+ .errorname = "ERROR",
+ },
+ }
+};
+
+static struct ipt_table nat_table = {
+ .name = "nat",
+ .valid_hooks = NAT_VALID_HOOKS,
+ .lock = RW_LOCK_UNLOCKED,
+ .me = THIS_MODULE,
+ .af = AF_INET,
+};
+
+/* Source NAT */
+static unsigned int ipt_snat_target(struct sk_buff **pskb,
+ const struct net_device *in,
+ const struct net_device *out,
+ unsigned int hooknum,
+ const struct xt_target *target,
+ const void *targinfo)
+{
+ struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+ const struct nf_nat_multi_range_compat *mr = targinfo;
+
+ NF_CT_ASSERT(hooknum == NF_IP_POST_ROUTING);
+
+ ct = nf_ct_get(*pskb, &ctinfo);
+
+ /* Connection must be valid and new. */
+ NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
+ ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
+ NF_CT_ASSERT(out);
+
+ return nf_nat_setup_info(ct, &mr->range[0], hooknum);
+}
+
+/* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
+static void warn_if_extra_mangle(__be32 dstip, __be32 srcip)
+{
+ static int warned = 0;
+ struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } };
+ struct rtable *rt;
+
+ if (ip_route_output_key(&rt, &fl) != 0)
+ return;
+
+ if (rt->rt_src != srcip && !warned) {
+ printk("NAT: no longer support implicit source local NAT\n");
+ printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
+ NIPQUAD(srcip), NIPQUAD(dstip));
+ warned = 1;
+ }
+ ip_rt_put(rt);
+}
+
+static unsigned int ipt_dnat_target(struct sk_buff **pskb,
+ const struct net_device *in,
+ const struct net_device *out,
+ unsigned int hooknum,
+ const struct xt_target *target,
+ const void *targinfo)
+{
+ struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+ const struct nf_nat_multi_range_compat *mr = targinfo;
+
+ NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING ||
+ hooknum == NF_IP_LOCAL_OUT);
+
+ ct = nf_ct_get(*pskb, &ctinfo);
+
+ /* Connection must be valid and new. */
+ NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
+
+ if (hooknum == NF_IP_LOCAL_OUT &&
+ mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
+ warn_if_extra_mangle((*pskb)->nh.iph->daddr,
+ mr->range[0].min_ip);
+
+ return nf_nat_setup_info(ct, &mr->range[0], hooknum);
+}
+
+static int ipt_snat_checkentry(const char *tablename,
+ const void *entry,
+ const struct xt_target *target,
+ void *targinfo,
+ unsigned int hook_mask)
+{
+ struct nf_nat_multi_range_compat *mr = targinfo;
+
+ /* Must be a valid range */
+ if (mr->rangesize != 1) {
+ printk("SNAT: multiple ranges no longer supported\n");
+ return 0;
+ }
+ return 1;
+}
+
+static int ipt_dnat_checkentry(const char *tablename,
+ const void *entry,
+ const struct xt_target *target,
+ void *targinfo,
+ unsigned int hook_mask)
+{
+ struct nf_nat_multi_range_compat *mr = targinfo;
+
+ /* Must be a valid range */
+ if (mr->rangesize != 1) {
+ printk("DNAT: multiple ranges no longer supported\n");
+ return 0;
+ }
+ return 1;
+}
+
+inline unsigned int
+alloc_null_binding(struct nf_conn *ct,
+ struct nf_nat_info *info,
+ unsigned int hooknum)
+{
+ /* Force range to this IP; let proto decide mapping for
+ per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
+ Use reply in case it's already been mangled (eg local packet).
+ */
+ __be32 ip
+ = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
+ ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
+ : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
+ struct nf_nat_range range
+ = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
+
+ DEBUGP("Allocating NULL binding for %p (%u.%u.%u.%u)\n",
+ ct, NIPQUAD(ip));
+ return nf_nat_setup_info(ct, &range, hooknum);
+}
+
+unsigned int
+alloc_null_binding_confirmed(struct nf_conn *ct,
+ struct nf_nat_info *info,
+ unsigned int hooknum)
+{
+ __be32 ip
+ = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
+ ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
+ : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
+ u_int16_t all
+ = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
+ ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
+ : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
+ struct nf_nat_range range
+ = { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
+
+ DEBUGP("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
+ ct, NIPQUAD(ip));
+ return nf_nat_setup_info(ct, &range, hooknum);
+}
+
+int nf_nat_rule_find(struct sk_buff **pskb,
+ unsigned int hooknum,
+ const struct net_device *in,
+ const struct net_device *out,
+ struct nf_conn *ct,
+ struct nf_nat_info *info)
+{
+ int ret;
+
+ ret = ipt_do_table(pskb, hooknum, in, out, &nat_table);
+
+ if (ret == NF_ACCEPT) {
+ if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
+ /* NUL mapping */
+ ret = alloc_null_binding(ct, info, hooknum);
+ }
+ return ret;
+}
+
+static struct ipt_target ipt_snat_reg = {
+ .name = "SNAT",
+ .target = ipt_snat_target,
+ .targetsize = sizeof(struct nf_nat_multi_range_compat),
+ .table = "nat",
+ .hooks = 1 << NF_IP_POST_ROUTING,
+ .checkentry = ipt_snat_checkentry,
+ .family = AF_INET,
+};
+
+static struct xt_target ipt_dnat_reg = {
+ .name = "DNAT",
+ .target = ipt_dnat_target,
+ .targetsize = sizeof(struct nf_nat_multi_range_compat),
+ .table = "nat",
+ .hooks = (1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT),
+ .checkentry = ipt_dnat_checkentry,
+ .family = AF_INET,
+};
+
+int __init nf_nat_rule_init(void)
+{
+ int ret;
+
+ ret = ipt_register_table(&nat_table, &nat_initial_table.repl);
+ if (ret != 0)
+ return ret;
+ ret = xt_register_target(&ipt_snat_reg);
+ if (ret != 0)
+ goto unregister_table;
+
+ ret = xt_register_target(&ipt_dnat_reg);
+ if (ret != 0)
+ goto unregister_snat;
+
+ return ret;
+
+ unregister_snat:
+ xt_unregister_target(&ipt_snat_reg);
+ unregister_table:
+ ipt_unregister_table(&nat_table);
+
+ return ret;
+}
+
+void nf_nat_rule_cleanup(void)
+{
+ xt_unregister_target(&ipt_dnat_reg);
+ xt_unregister_target(&ipt_snat_reg);
+ ipt_unregister_table(&nat_table);
+}