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#define __NO_VERSION__
#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 <linux/bitops.h>
#include <linux/version.h>
#define ASSERT_READ_LOCK(x) MUST_BE_READ_LOCKED(&ip_nat_lock)
#define ASSERT_WRITE_LOCK(x) MUST_BE_WRITE_LOCKED(&ip_nat_lock)
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_core.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/listhelp.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))
/* Standard entry. */
struct ipt_standard
{
struct ipt_entry entry;
struct ipt_standard_target target;
};
struct ipt_error_target
{
struct ipt_entry_target target;
char errorname[IPT_FUNCTION_MAXNAMELEN];
};
struct ipt_error
{
struct ipt_entry entry;
struct ipt_error_target target;
};
static struct
{
struct ipt_replace repl;
struct ipt_standard entries[3];
struct ipt_error term;
} nat_initial_table __initdata
= { { "nat", NAT_VALID_HOOKS, 4,
sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
{ [NF_IP_PRE_ROUTING] 0,
[NF_IP_POST_ROUTING] sizeof(struct ipt_standard),
[NF_IP_LOCAL_OUT] sizeof(struct ipt_standard) * 2 },
{ [NF_IP_PRE_ROUTING] 0,
[NF_IP_POST_ROUTING] sizeof(struct ipt_standard),
[NF_IP_LOCAL_OUT] sizeof(struct ipt_standard) * 2 },
0, NULL, { } },
{
/* PRE_ROUTING */
{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
0,
sizeof(struct ipt_entry),
sizeof(struct ipt_standard),
0, { 0, 0 }, { } },
{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
-NF_ACCEPT - 1 } },
/* POST_ROUTING */
{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
0,
sizeof(struct ipt_entry),
sizeof(struct ipt_standard),
0, { 0, 0 }, { } },
{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
-NF_ACCEPT - 1 } },
/* LOCAL_OUT */
{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
0,
sizeof(struct ipt_entry),
sizeof(struct ipt_standard),
0, { 0, 0 }, { } },
{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
-NF_ACCEPT - 1 } }
},
/* ERROR */
{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
0,
sizeof(struct ipt_entry),
sizeof(struct ipt_error),
0, { 0, 0 }, { } },
{ { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } },
{ } },
"ERROR"
}
}
};
static struct ipt_table nat_table
= { { NULL, NULL }, "nat", &nat_initial_table.repl,
NAT_VALID_HOOKS, RW_LOCK_UNLOCKED, NULL };
LIST_HEAD(nat_expect_list);
/* Source NAT */
static unsigned int ipt_snat_target(struct sk_buff **pskb,
unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
const void *targinfo,
void *userinfo)
{
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
ct = ip_conntrack_get(*pskb, &ctinfo);
/* Connection must be valid and new. */
IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
IP_NF_ASSERT(out);
return ip_nat_setup_info(ct, targinfo, hooknum);
}
static unsigned int ipt_dnat_target(struct sk_buff **pskb,
unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
const void *targinfo,
void *userinfo)
{
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING
|| hooknum == NF_IP_LOCAL_OUT);
ct = ip_conntrack_get(*pskb, &ctinfo);
/* Connection must be valid and new. */
IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
return ip_nat_setup_info(ct, targinfo, hooknum);
}
static int ipt_snat_checkentry(const char *tablename,
const struct ipt_entry *e,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
struct ip_nat_multi_range *mr = targinfo;
/* Must be a valid range */
if (targinfosize < sizeof(struct ip_nat_multi_range)) {
DEBUGP("SNAT: Target size %u too small\n", targinfosize);
return 0;
}
if (targinfosize != IPT_ALIGN((sizeof(struct ip_nat_multi_range)
+ (sizeof(struct ip_nat_range)
* (mr->rangesize - 1))))) {
DEBUGP("SNAT: Target size %u wrong for %u ranges\n",
targinfosize, mr->rangesize);
return 0;
}
/* Only allow these for NAT. */
if (strcmp(tablename, "nat") != 0) {
DEBUGP("SNAT: wrong table %s\n", tablename);
return 0;
}
if (hook_mask & ~(1 << NF_IP_POST_ROUTING)) {
DEBUGP("SNAT: hook mask 0x%x bad\n", hook_mask);
return 0;
}
return 1;
}
static int ipt_dnat_checkentry(const char *tablename,
const struct ipt_entry *e,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
struct ip_nat_multi_range *mr = targinfo;
/* Must be a valid range */
if (targinfosize < sizeof(struct ip_nat_multi_range)) {
DEBUGP("DNAT: Target size %u too small\n", targinfosize);
return 0;
}
if (targinfosize != IPT_ALIGN((sizeof(struct ip_nat_multi_range)
+ (sizeof(struct ip_nat_range)
* (mr->rangesize - 1))))) {
DEBUGP("DNAT: Target size %u wrong for %u ranges\n",
targinfosize, mr->rangesize);
return 0;
}
/* Only allow these for NAT. */
if (strcmp(tablename, "nat") != 0) {
DEBUGP("SNAT: wrong table %s\n", tablename);
return 0;
}
if (hook_mask & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT))) {
DEBUGP("DNAT: hook mask 0x%x bad\n", hook_mask);
return 0;
}
return 1;
}
static inline unsigned int
alloc_null_binding(struct ip_conntrack *conntrack,
struct ip_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).
*/
u_int32_t ip
= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
? conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip
: conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip);
struct ip_nat_multi_range mr
= { 1, { { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } } } };
DEBUGP("Allocating NULL binding for %p (%u.%u.%u.%u)\n", conntrack,
NIPQUAD(ip));
return ip_nat_setup_info(conntrack, &mr, hooknum);
}
static inline int call_expect(const struct ip_nat_expect *i,
struct sk_buff **pskb,
unsigned int hooknum,
struct ip_conntrack *ct,
struct ip_nat_info *info,
struct ip_conntrack *master,
struct ip_nat_info *masterinfo,
unsigned int *verdict)
{
return i->expect(pskb, hooknum, ct, info, master, masterinfo,
verdict);
}
int ip_nat_rule_find(struct sk_buff **pskb,
unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
struct ip_conntrack *ct,
struct ip_nat_info *info)
{
int ret;
/* Master won't vanish while this ctrack still alive */
if (ct->master.master) {
struct ip_conntrack *master;
master = (struct ip_conntrack *)ct->master.master;
if (LIST_FIND(&nat_expect_list,
call_expect,
struct ip_nat_expect *,
pskb, hooknum, ct, info,
master, &master->nat.info, &ret))
return ret;
}
ret = ipt_do_table(pskb, hooknum, in, out, &nat_table, NULL);
if (ret == NF_ACCEPT) {
if (!(info->initialized & (1 << HOOK2MANIP(hooknum))))
/* NUL mapping */
ret = alloc_null_binding(ct, info, hooknum);
}
return ret;
}
int ip_nat_expect_register(struct ip_nat_expect *expect)
{
WRITE_LOCK(&ip_nat_lock);
list_prepend(&nat_expect_list, expect);
WRITE_UNLOCK(&ip_nat_lock);
return 0;
}
void ip_nat_expect_unregister(struct ip_nat_expect *expect)
{
WRITE_LOCK(&ip_nat_lock);
LIST_DELETE(&nat_expect_list, expect);
WRITE_UNLOCK(&ip_nat_lock);
}
static struct ipt_target ipt_snat_reg
= { { NULL, NULL }, "SNAT", ipt_snat_target, ipt_snat_checkentry, NULL };
static struct ipt_target ipt_dnat_reg
= { { NULL, NULL }, "DNAT", ipt_dnat_target, ipt_dnat_checkentry, NULL };
int __init ip_nat_rule_init(void)
{
int ret;
ret = ipt_register_table(&nat_table);
if (ret != 0)
return ret;
ret = ipt_register_target(&ipt_snat_reg);
if (ret != 0)
goto unregister_table;
ret = ipt_register_target(&ipt_dnat_reg);
if (ret != 0)
goto unregister_snat;
return ret;
unregister_snat:
ipt_unregister_target(&ipt_snat_reg);
unregister_table:
ipt_unregister_table(&nat_table);
return ret;
}
void ip_nat_rule_cleanup(void)
{
ipt_unregister_target(&ipt_dnat_reg);
ipt_unregister_target(&ipt_snat_reg);
ipt_unregister_table(&nat_table);
}
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