[deliverable/linux.git] / net / ipv4 / netfilter / iptable_mangle.c

/*
 * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
 *
 * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
 * Copyright (C) 2000-2004 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.
 *
 * Extended to all five netfilter hooks by Brad Chapman & Harald Welte
 */
#include <linux/module.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/route.h>
#include <linux/ip.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("iptables mangle table");

#define MANGLE_VALID_HOOKS ((1 << NF_IP_PRE_ROUTING) | \
			    (1 << NF_IP_LOCAL_IN) | \
			    (1 << NF_IP_FORWARD) | \
			    (1 << NF_IP_LOCAL_OUT) | \
			    (1 << NF_IP_POST_ROUTING))

/* Ouch - five different hooks? Maybe this should be a config option..... -- BC */
static struct
{
	struct ipt_replace repl;
	struct ipt_standard entries[5];
	struct ipt_error term;
} initial_table __initdata
= { { "mangle", MANGLE_VALID_HOOKS, 6,
      sizeof(struct ipt_standard) * 5 + sizeof(struct ipt_error),
      { [NF_IP_PRE_ROUTING] 	= 0,
	[NF_IP_LOCAL_IN] 	= sizeof(struct ipt_standard),
	[NF_IP_FORWARD] 	= sizeof(struct ipt_standard) * 2,
	[NF_IP_LOCAL_OUT] 	= sizeof(struct ipt_standard) * 3,
	[NF_IP_POST_ROUTING] 	= sizeof(struct ipt_standard) * 4 },
      { [NF_IP_PRE_ROUTING] 	= 0,
	[NF_IP_LOCAL_IN] 	= sizeof(struct ipt_standard),
	[NF_IP_FORWARD] 	= sizeof(struct ipt_standard) * 2,
	[NF_IP_LOCAL_OUT] 	= sizeof(struct ipt_standard) * 3,
	[NF_IP_POST_ROUTING]	= sizeof(struct ipt_standard) * 4 },
      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 } },
	    /* LOCAL_IN */
 	    { { { { 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 } },
	    /* FORWARD */
 	    { { { { 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 } },
	    /* 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 } },
    },
    /* 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 xt_table packet_mangler = {
	.name		= "mangle",
	.valid_hooks	= MANGLE_VALID_HOOKS,
	.lock		= RW_LOCK_UNLOCKED,
	.me		= THIS_MODULE,
	.af		= AF_INET,
};

/* The work comes in here from netfilter.c. */
static unsigned int
ipt_route_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);
}

static unsigned int
ipt_local_hook(unsigned int hook,
		   struct sk_buff **pskb,
		   const struct net_device *in,
		   const struct net_device *out,
		   int (*okfn)(struct sk_buff *))
{
	unsigned int ret;
	u_int8_t tos;
	__be32 saddr, daddr;
	u_int32_t mark;

	/* 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;
	}

	/* Save things which could affect route */
	mark = (*pskb)->mark;
	saddr = (*pskb)->nh.iph->saddr;
	daddr = (*pskb)->nh.iph->daddr;
	tos = (*pskb)->nh.iph->tos;

	ret = ipt_do_table(pskb, hook, in, out, &packet_mangler);
	/* Reroute for ANY change. */
	if (ret != NF_DROP && ret != NF_STOLEN && ret != NF_QUEUE
	    && ((*pskb)->nh.iph->saddr != saddr
		|| (*pskb)->nh.iph->daddr != daddr
		|| (*pskb)->mark != mark
		|| (*pskb)->nh.iph->tos != tos))
		if (ip_route_me_harder(pskb, RTN_UNSPEC))
			ret = NF_DROP;

	return ret;
}

static struct nf_hook_ops ipt_ops[] = {
	{
		.hook		= ipt_route_hook,
		.owner		= THIS_MODULE,
		.pf		= PF_INET,
		.hooknum	= NF_IP_PRE_ROUTING, 
		.priority	= NF_IP_PRI_MANGLE,
	},
	{
		.hook		= ipt_route_hook,
		.owner		= THIS_MODULE,
		.pf		= PF_INET,
		.hooknum	= NF_IP_LOCAL_IN,
		.priority	= NF_IP_PRI_MANGLE,
	},
	{
		.hook		= ipt_route_hook,
		.owner		= THIS_MODULE,
		.pf		= PF_INET,
		.hooknum	= NF_IP_FORWARD,
		.priority	= NF_IP_PRI_MANGLE,
	},
	{
		.hook		= ipt_local_hook,
		.owner		= THIS_MODULE,
		.pf		= PF_INET,
		.hooknum	= NF_IP_LOCAL_OUT,
		.priority	= NF_IP_PRI_MANGLE,
	},
	{
		.hook		= ipt_route_hook,
		.owner		= THIS_MODULE,
		.pf		= PF_INET,
		.hooknum	= NF_IP_POST_ROUTING,
		.priority	= NF_IP_PRI_MANGLE,
	},
};

static int __init iptable_mangle_init(void)
{
	int ret;

	/* Register table */
	ret = ipt_register_table(&packet_mangler, &initial_table.repl);
	if (ret < 0)
		return ret;

	/* Register hooks */
	ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
	if (ret < 0)
		goto cleanup_table;

	return ret;

 cleanup_table:
	ipt_unregister_table(&packet_mangler);
	return ret;
}

static void __exit iptable_mangle_fini(void)
{
	nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
	ipt_unregister_table(&packet_mangler);
}

module_init(iptable_mangle_init);
module_exit(iptable_mangle_fini);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
	3	*
	4	* Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
	5	* Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*
	11	* Extended to all five netfilter hooks by Brad Chapman & Harald Welte
	12	*/
1da177e4 LT	13	#include <linux/module.h>
	14	#include <linux/netfilter_ipv4/ip_tables.h>
	15	#include <linux/netdevice.h>
	16	#include <linux/skbuff.h>
	17	#include <net/sock.h>
	18	#include <net/route.h>
	19	#include <linux/ip.h>
	20
	21	MODULE_LICENSE("GPL");
	22	MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
	23	MODULE_DESCRIPTION("iptables mangle table");
	24
	25	#define MANGLE_VALID_HOOKS ((1 << NF_IP_PRE_ROUTING) \| \
	26	(1 << NF_IP_LOCAL_IN) \| \
	27	(1 << NF_IP_FORWARD) \| \
	28	(1 << NF_IP_LOCAL_OUT) \| \
	29	(1 << NF_IP_POST_ROUTING))
	30
	31	/* Ouch - five different hooks? Maybe this should be a config option..... -- BC */
	32	static struct
	33	{
	34	struct ipt_replace repl;
	35	struct ipt_standard entries[5];
	36	struct ipt_error term;
	37	} initial_table __initdata
	38	= { { "mangle", MANGLE_VALID_HOOKS, 6,
	39	sizeof(struct ipt_standard) * 5 + sizeof(struct ipt_error),
	40	{ [NF_IP_PRE_ROUTING] = 0,
	41	[NF_IP_LOCAL_IN] = sizeof(struct ipt_standard),
	42	[NF_IP_FORWARD] = sizeof(struct ipt_standard) * 2,
	43	[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 3,
	44	[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard) * 4 },
	45	{ [NF_IP_PRE_ROUTING] = 0,
	46	[NF_IP_LOCAL_IN] = sizeof(struct ipt_standard),
	47	[NF_IP_FORWARD] = sizeof(struct ipt_standard) * 2,
	48	[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 3,
	49	[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard) * 4 },
	50	0, NULL, { } },
	51	{
	52	/* PRE_ROUTING */
	53	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
	54	0,
	55	sizeof(struct ipt_entry),
	56	sizeof(struct ipt_standard),
	57	0, { 0, 0 }, { } },
	58	{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
	59	-NF_ACCEPT - 1 } },
	60	/* LOCAL_IN */
	61	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
	62	0,
	63	sizeof(struct ipt_entry),
	64	sizeof(struct ipt_standard),
	65	0, { 0, 0 }, { } },
	66	{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
	67	-NF_ACCEPT - 1 } },
	68	/* FORWARD */
	69	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
	70	0,
	71	sizeof(struct ipt_entry),
	72	sizeof(struct ipt_standard),
	73	0, { 0, 0 }, { } },
	74	{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
	75	-NF_ACCEPT - 1 } },
	76	/* LOCAL_OUT */
77	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
78	0,
79	sizeof(struct ipt_entry),
80	sizeof(struct ipt_standard),
81	0, { 0, 0 }, { } },
82	{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
83	-NF_ACCEPT - 1 } },
84	/* POST_ROUTING */
85	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
86	0,
87	sizeof(struct ipt_entry),
88	sizeof(struct ipt_standard),
89	0, { 0, 0 }, { } },
90	{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
91	-NF_ACCEPT - 1 } },
92	},
93	/* ERROR */
94	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
95	0,
96	sizeof(struct ipt_entry),
97	sizeof(struct ipt_error),
98	0, { 0, 0 }, { } },
99	{ { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } },
100	{ } },
101	"ERROR"
102	}
103	}
104	};
105
e60a13e0	106	static struct xt_table packet_mangler = {
1da177e4 LT	107	.name = "mangle",
	108	.valid_hooks = MANGLE_VALID_HOOKS,
	109	.lock = RW_LOCK_UNLOCKED,
	110	.me = THIS_MODULE,
2e4e6a17	111	.af = AF_INET,
1da177e4 LT	112	};
	113
	114	/* The work comes in here from netfilter.c. */
	115	static unsigned int
	116	ipt_route_hook(unsigned int hook,
	117	struct sk_buff **pskb,
	118	const struct net_device *in,
	119	const struct net_device *out,
	120	int (okfn)(struct sk_buff ))
	121	{
fe1cb108	122	return ipt_do_table(pskb, hook, in, out, &packet_mangler);
1da177e4 LT	123	}
	124
	125	static unsigned int
	126	ipt_local_hook(unsigned int hook,
	127	struct sk_buff **pskb,
	128	const struct net_device *in,
	129	const struct net_device *out,
	130	int (okfn)(struct sk_buff ))
	131	{
	132	unsigned int ret;
	133	u_int8_t tos;
6a19d614	134	__be32 saddr, daddr;
82e91ffe	135	u_int32_t mark;
1da177e4 LT	136
	137	/* root is playing with raw sockets. */
	138	if ((*pskb)->len < sizeof(struct iphdr)
	139	\|\| (pskb)->nh.iph->ihl 4 < sizeof(struct iphdr)) {
	140	if (net_ratelimit())
	141	printk("ipt_hook: happy cracking.\n");
	142	return NF_ACCEPT;
	143	}
	144
	145	/* Save things which could affect route */
82e91ffe	146	mark = (*pskb)->mark;
1da177e4 LT	147	saddr = (*pskb)->nh.iph->saddr;
	148	daddr = (*pskb)->nh.iph->daddr;
	149	tos = (*pskb)->nh.iph->tos;
	150
fe1cb108	151	ret = ipt_do_table(pskb, hook, in, out, &packet_mangler);
1da177e4 LT	152	/* Reroute for ANY change. */
	153	if (ret != NF_DROP && ret != NF_STOLEN && ret != NF_QUEUE
	154	&& ((*pskb)->nh.iph->saddr != saddr
	155	\|\| (*pskb)->nh.iph->daddr != daddr
82e91ffe	156	\|\| (*pskb)->mark != mark
1da177e4	157	\|\| (*pskb)->nh.iph->tos != tos))
b4c4ed17 SH	158	if (ip_route_me_harder(pskb, RTN_UNSPEC))
b4c4ed17 SH	159	ret = NF_DROP;
1da177e4 LT	160
	161	return ret;
	162	}
	163
	164	static struct nf_hook_ops ipt_ops[] = {
	165	{
	166	.hook = ipt_route_hook,
	167	.owner = THIS_MODULE,
	168	.pf = PF_INET,
	169	.hooknum = NF_IP_PRE_ROUTING,
	170	.priority = NF_IP_PRI_MANGLE,
	171	},
	172	{
	173	.hook = ipt_route_hook,
	174	.owner = THIS_MODULE,
	175	.pf = PF_INET,
	176	.hooknum = NF_IP_LOCAL_IN,
	177	.priority = NF_IP_PRI_MANGLE,
	178	},
	179	{
	180	.hook = ipt_route_hook,
	181	.owner = THIS_MODULE,
	182	.pf = PF_INET,
	183	.hooknum = NF_IP_FORWARD,
	184	.priority = NF_IP_PRI_MANGLE,
	185	},
	186	{
	187	.hook = ipt_local_hook,
	188	.owner = THIS_MODULE,
	189	.pf = PF_INET,
	190	.hooknum = NF_IP_LOCAL_OUT,
	191	.priority = NF_IP_PRI_MANGLE,
	192	},
	193	{
	194	.hook = ipt_route_hook,
	195	.owner = THIS_MODULE,
	196	.pf = PF_INET,
	197	.hooknum = NF_IP_POST_ROUTING,
	198	.priority = NF_IP_PRI_MANGLE,
	199	},
	200	};
	201
65b4b4e8	202	static int __init iptable_mangle_init(void)
1da177e4 LT	203	{
	204	int ret;
	205
	206	/* Register table */
	207	ret = ipt_register_table(&packet_mangler, &initial_table.repl);
	208	if (ret < 0)
	209	return ret;
	210
	211	/* Register hooks */
964ddaa1	212	ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
1da177e4 LT	213	if (ret < 0)
	214	goto cleanup_table;
	215
1da177e4 LT	216	return ret;
1da177e4 LT	217
1da177e4 LT	218	cleanup_table:
1da177e4 LT	219	ipt_unregister_table(&packet_mangler);
1da177e4 LT	220	return ret;
	221	}
	222
65b4b4e8	223	static void __exit iptable_mangle_fini(void)
1da177e4	224	{
964ddaa1	225	nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
1da177e4 LT	226	ipt_unregister_table(&packet_mangler);
	227	}
	228
65b4b4e8 AM	229	module_init(iptable_mangle_init);
65b4b4e8 AM	230	module_exit(iptable_mangle_fini);