[GitHub/LineageOS/android_kernel_motorola_exynos9610.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>
#include <net/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;
	const struct iphdr *iph;
	u_int8_t tos;
	__be32 saddr, daddr;
	u_int32_t mark;

	/* root is playing with raw sockets. */
	if ((*pskb)->len < sizeof(struct iphdr)
	    || ip_hdrlen(*pskb) < sizeof(struct iphdr)) {
		if (net_ratelimit())
			printk("ipt_hook: happy cracking.\n");
		return NF_ACCEPT;
	}

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

		if (iph->saddr != saddr ||
		    iph->daddr != daddr ||
		    (*pskb)->mark != mark ||
		    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>
c9bdd4b5	20	#include <net/ip.h>
1da177e4 LT	21
	22	MODULE_LICENSE("GPL");
	23	MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
	24	MODULE_DESCRIPTION("iptables mangle table");
	25
	26	#define MANGLE_VALID_HOOKS ((1 << NF_IP_PRE_ROUTING) \| \
	27	(1 << NF_IP_LOCAL_IN) \| \
	28	(1 << NF_IP_FORWARD) \| \
	29	(1 << NF_IP_LOCAL_OUT) \| \
	30	(1 << NF_IP_POST_ROUTING))
	31
	32	/* Ouch - five different hooks? Maybe this should be a config option..... -- BC */
	33	static struct
	34	{
	35	struct ipt_replace repl;
	36	struct ipt_standard entries[5];
	37	struct ipt_error term;
	38	} initial_table __initdata
	39	= { { "mangle", MANGLE_VALID_HOOKS, 6,
	40	sizeof(struct ipt_standard) * 5 + sizeof(struct ipt_error),
	41	{ [NF_IP_PRE_ROUTING] = 0,
	42	[NF_IP_LOCAL_IN] = sizeof(struct ipt_standard),
	43	[NF_IP_FORWARD] = sizeof(struct ipt_standard) * 2,
	44	[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 3,
	45	[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard) * 4 },
	46	{ [NF_IP_PRE_ROUTING] = 0,
	47	[NF_IP_LOCAL_IN] = sizeof(struct ipt_standard),
	48	[NF_IP_FORWARD] = sizeof(struct ipt_standard) * 2,
	49	[NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 3,
	50	[NF_IP_POST_ROUTING] = sizeof(struct ipt_standard) * 4 },
	51	0, NULL, { } },
	52	{
	53	/* PRE_ROUTING */
	54	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
	55	0,
	56	sizeof(struct ipt_entry),
	57	sizeof(struct ipt_standard),
	58	0, { 0, 0 }, { } },
	59	{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
	60	-NF_ACCEPT - 1 } },
	61	/* LOCAL_IN */
e905a9ed	62	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
1da177e4 LT	63	0,
	64	sizeof(struct ipt_entry),
	65	sizeof(struct ipt_standard),
	66	0, { 0, 0 }, { } },
	67	{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
	68	-NF_ACCEPT - 1 } },
	69	/* FORWARD */
e905a9ed	70	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
1da177e4 LT	71	0,
	72	sizeof(struct ipt_entry),
	73	sizeof(struct ipt_standard),
	74	0, { 0, 0 }, { } },
	75	{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
	76	-NF_ACCEPT - 1 } },
	77	/* LOCAL_OUT */
	78	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
	79	0,
	80	sizeof(struct ipt_entry),
	81	sizeof(struct ipt_standard),
	82	0, { 0, 0 }, { } },
	83	{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
	84	-NF_ACCEPT - 1 } },
	85	/* POST_ROUTING */
	86	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
	87	0,
	88	sizeof(struct ipt_entry),
	89	sizeof(struct ipt_standard),
	90	0, { 0, 0 }, { } },
	91	{ { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } },
	92	-NF_ACCEPT - 1 } },
	93	},
	94	/* ERROR */
	95	{ { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 },
	96	0,
	97	sizeof(struct ipt_entry),
	98	sizeof(struct ipt_error),
	99	0, { 0, 0 }, { } },
	100	{ { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } },
	101	{ } },
	102	"ERROR"
	103	}
	104	}
	105	};
	106
e60a13e0	107	static struct xt_table packet_mangler = {
1da177e4 LT	108	.name = "mangle",
	109	.valid_hooks = MANGLE_VALID_HOOKS,
	110	.lock = RW_LOCK_UNLOCKED,
	111	.me = THIS_MODULE,
2e4e6a17	112	.af = AF_INET,
1da177e4 LT	113	};
	114
	115	/* The work comes in here from netfilter.c. */
	116	static unsigned int
	117	ipt_route_hook(unsigned int hook,
	118	struct sk_buff **pskb,
	119	const struct net_device *in,
	120	const struct net_device *out,
	121	int (okfn)(struct sk_buff ))
	122	{
fe1cb108	123	return ipt_do_table(pskb, hook, in, out, &packet_mangler);
1da177e4 LT	124	}
	125
	126	static unsigned int
	127	ipt_local_hook(unsigned int hook,
	128	struct sk_buff **pskb,
	129	const struct net_device *in,
	130	const struct net_device *out,
	131	int (okfn)(struct sk_buff ))
	132	{
	133	unsigned int ret;
eddc9ec5	134	const struct iphdr *iph;
1da177e4	135	u_int8_t tos;
6a19d614	136	__be32 saddr, daddr;
82e91ffe	137	u_int32_t mark;
1da177e4 LT	138
	139	/* root is playing with raw sockets. */
	140	if ((*pskb)->len < sizeof(struct iphdr)
c9bdd4b5	141	\|\| ip_hdrlen(*pskb) < sizeof(struct iphdr)) {
1da177e4 LT	142	if (net_ratelimit())
	143	printk("ipt_hook: happy cracking.\n");
	144	return NF_ACCEPT;
	145	}
	146
	147	/* Save things which could affect route */
82e91ffe	148	mark = (*pskb)->mark;
eddc9ec5 ACM	149	iph = ip_hdr(*pskb);
	150	saddr = iph->saddr;
	151	daddr = iph->daddr;
	152	tos = iph->tos;
1da177e4	153
fe1cb108	154	ret = ipt_do_table(pskb, hook, in, out, &packet_mangler);
1da177e4	155	/* Reroute for ANY change. */
eddc9ec5 ACM	156	if (ret != NF_DROP && ret != NF_STOLEN && ret != NF_QUEUE) {
	157	iph = ip_hdr(*pskb);
	158
	159	if (iph->saddr != saddr \|\|
	160	iph->daddr != daddr \|\|
	161	(*pskb)->mark != mark \|\|
	162	iph->tos != tos)
	163	if (ip_route_me_harder(pskb, RTN_UNSPEC))
	164	ret = NF_DROP;
	165	}
1da177e4 LT	166
	167	return ret;
	168	}
	169
	170	static struct nf_hook_ops ipt_ops[] = {
	171	{
	172	.hook = ipt_route_hook,
	173	.owner = THIS_MODULE,
	174	.pf = PF_INET,
e905a9ed	175	.hooknum = NF_IP_PRE_ROUTING,
1da177e4 LT	176	.priority = NF_IP_PRI_MANGLE,
	177	},
	178	{
	179	.hook = ipt_route_hook,
	180	.owner = THIS_MODULE,
	181	.pf = PF_INET,
	182	.hooknum = NF_IP_LOCAL_IN,
	183	.priority = NF_IP_PRI_MANGLE,
	184	},
	185	{
	186	.hook = ipt_route_hook,
	187	.owner = THIS_MODULE,
	188	.pf = PF_INET,
	189	.hooknum = NF_IP_FORWARD,
	190	.priority = NF_IP_PRI_MANGLE,
	191	},
	192	{
	193	.hook = ipt_local_hook,
	194	.owner = THIS_MODULE,
	195	.pf = PF_INET,
	196	.hooknum = NF_IP_LOCAL_OUT,
	197	.priority = NF_IP_PRI_MANGLE,
	198	},
	199	{
	200	.hook = ipt_route_hook,
	201	.owner = THIS_MODULE,
	202	.pf = PF_INET,
	203	.hooknum = NF_IP_POST_ROUTING,
	204	.priority = NF_IP_PRI_MANGLE,
	205	},
	206	};
	207
65b4b4e8	208	static int __init iptable_mangle_init(void)
1da177e4 LT	209	{
	210	int ret;
	211
	212	/* Register table */
	213	ret = ipt_register_table(&packet_mangler, &initial_table.repl);
	214	if (ret < 0)
	215	return ret;
	216
	217	/* Register hooks */
964ddaa1	218	ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
1da177e4 LT	219	if (ret < 0)
	220	goto cleanup_table;
	221
1da177e4 LT	222	return ret;
1da177e4 LT	223
1da177e4 LT	224	cleanup_table:
1da177e4 LT	225	ipt_unregister_table(&packet_mangler);
1da177e4 LT	226	return ret;
	227	}
	228
65b4b4e8	229	static void __exit iptable_mangle_fini(void)
1da177e4	230	{
964ddaa1	231	nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
1da177e4 LT	232	ipt_unregister_table(&packet_mangler);
	233	}
	234
65b4b4e8 AM	235	module_init(iptable_mangle_init);
65b4b4e8 AM	236	module_exit(iptable_mangle_fini);