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/*
* This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
*
* Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
*/
#include <linux/module.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#define MANGLE_VALID_HOOKS ((1 << NF_IP_PRE_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[2];
struct ipt_error term;
} initial_table __initdata
= { { "mangle", MANGLE_VALID_HOOKS, 3,
sizeof(struct ipt_standard) * 2 + sizeof(struct ipt_error),
{ [NF_IP_PRE_ROUTING] 0,
[NF_IP_LOCAL_OUT] sizeof(struct ipt_standard) },
{ [NF_IP_PRE_ROUTING] 0,
[NF_IP_LOCAL_OUT] sizeof(struct ipt_standard) },
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 }, { } },
{ { { { 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 }, { } },
{ { { { 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 }, { } },
{ { { { sizeof(struct ipt_error_target), IPT_ERROR_TARGET } },
{ } },
"ERROR"
}
}
};
static struct ipt_table packet_mangler
= { { NULL, NULL }, "mangle", &initial_table.repl,
MANGLE_VALID_HOOKS, RW_LOCK_UNLOCKED, NULL };
/* The work comes in here from netfilter.c. */
static unsigned int
ipt_hook(unsigned int hook,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
return ipt_do_table(pskb, hook, in, out, &packet_mangler, NULL);
}
static unsigned int
ipt_local_out_hook(unsigned int hook,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
/* root is playing with raw sockets. */
if ((*pskb)->len < sizeof(struct iphdr)
|| (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) {
if (net_ratelimit())
printk("ipt_hook: happy cracking.\n");
return NF_ACCEPT;
}
return ipt_do_table(pskb, hook, in, out, &packet_mangler, NULL);
}
static struct nf_hook_ops ipt_ops[]
= { { { NULL, NULL }, ipt_hook, PF_INET, NF_IP_PRE_ROUTING, NF_IP_PRI_MANGLE },
{ { NULL, NULL }, ipt_local_out_hook, PF_INET, NF_IP_LOCAL_OUT,
NF_IP_PRI_MANGLE }
};
static int __init init(void)
{
int ret;
/* Register table */
ret = ipt_register_table(&packet_mangler);
if (ret < 0)
return ret;
/* Register hooks */
ret = nf_register_hook(&ipt_ops[0]);
if (ret < 0)
goto cleanup_table;
ret = nf_register_hook(&ipt_ops[1]);
if (ret < 0)
goto cleanup_hook0;
return ret;
cleanup_hook0:
nf_unregister_hook(&ipt_ops[0]);
cleanup_table:
ipt_unregister_table(&packet_mangler);
return ret;
}
static void __exit fini(void)
{
unsigned int i;
for (i = 0; i < sizeof(ipt_ops)/sizeof(struct nf_hook_ops); i++)
nf_unregister_hook(&ipt_ops[i]);
ipt_unregister_table(&packet_mangler);
}
module_init(init);
module_exit(fini);
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