[net-next-2.6.git] / net / netfilter / xt_policy.c

/* IP tables module for matching IPsec policy
 *
 * Copyright (c) 2004,2005 Patrick McHardy, <kaber@trash.net>
 *
 * 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.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <net/xfrm.h>

#include <linux/netfilter/xt_policy.h>
#include <linux/netfilter/x_tables.h>

MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_DESCRIPTION("Xtables IPsec policy matching module");
MODULE_LICENSE("GPL");

static inline bool
xt_addr_cmp(const union xt_policy_addr *a1, const union xt_policy_addr *m,
	    const union xt_policy_addr *a2, unsigned short family)
{
	switch (family) {
	case AF_INET:
		return !((a1->a4.s_addr ^ a2->a4.s_addr) & m->a4.s_addr);
	case AF_INET6:
		return !ipv6_masked_addr_cmp(&a1->a6, &m->a6, &a2->a6);
	}
	return false;
}

static inline bool
match_xfrm_state(const struct xfrm_state *x, const struct xt_policy_elem *e,
		 unsigned short family)
{
#define MATCH_ADDR(x,y,z)	(!e->match.x ||			       \
				 (xt_addr_cmp(&e->x, &e->y, z, family) \
				  ^ e->invert.x))
#define MATCH(x,y)		(!e->match.x || ((e->x == (y)) ^ e->invert.x))

	return MATCH_ADDR(saddr, smask, (union xt_policy_addr *)&x->props.saddr) &&
	       MATCH_ADDR(daddr, dmask, (union xt_policy_addr *)&x->id.daddr) &&
	       MATCH(proto, x->id.proto) &&
	       MATCH(mode, x->props.mode) &&
	       MATCH(spi, x->id.spi) &&
	       MATCH(reqid, x->props.reqid);
}

static int
match_policy_in(const struct sk_buff *skb, const struct xt_policy_info *info,
		unsigned short family)
{
	const struct xt_policy_elem *e;
	const struct sec_path *sp = skb->sp;
	int strict = info->flags & XT_POLICY_MATCH_STRICT;
	int i, pos;

	if (sp == NULL)
		return -1;
	if (strict && info->len != sp->len)
		return 0;

	for (i = sp->len - 1; i >= 0; i--) {
		pos = strict ? i - sp->len + 1 : 0;
		if (pos >= info->len)
			return 0;
		e = &info->pol[pos];

		if (match_xfrm_state(sp->xvec[i], e, family)) {
			if (!strict)
				return 1;
		} else if (strict)
			return 0;
	}

	return strict ? 1 : 0;
}

static int
match_policy_out(const struct sk_buff *skb, const struct xt_policy_info *info,
		 unsigned short family)
{
	const struct xt_policy_elem *e;
	const struct dst_entry *dst = skb->dst;
	int strict = info->flags & XT_POLICY_MATCH_STRICT;
	int i, pos;

	if (dst->xfrm == NULL)
		return -1;

	for (i = 0; dst && dst->xfrm; dst = dst->child, i++) {
		pos = strict ? i : 0;
		if (pos >= info->len)
			return 0;
		e = &info->pol[pos];

		if (match_xfrm_state(dst->xfrm, e, family)) {
			if (!strict)
				return 1;
		} else if (strict)
			return 0;
	}

	return strict ? i == info->len : 0;
}

static bool match(const struct sk_buff *skb,
		  const struct net_device *in,
		  const struct net_device *out,
		  const struct xt_match *match,
		  const void *matchinfo,
		  int offset,
		  unsigned int protoff,
		  bool *hotdrop)
{
	const struct xt_policy_info *info = matchinfo;
	int ret;

	if (info->flags & XT_POLICY_MATCH_IN)
		ret = match_policy_in(skb, info, match->family);
	else
		ret = match_policy_out(skb, info, match->family);

	if (ret < 0)
		ret = info->flags & XT_POLICY_MATCH_NONE ? true : false;
	else if (info->flags & XT_POLICY_MATCH_NONE)
		ret = false;

	return ret;
}

static bool checkentry(const char *tablename, const void *ip_void,
		       const struct xt_match *match,
		       void *matchinfo, unsigned int hook_mask)
{
	struct xt_policy_info *info = matchinfo;

	if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT))) {
		printk(KERN_ERR "xt_policy: neither incoming nor "
				"outgoing policy selected\n");
		return false;
	}
	if (hook_mask & (1 << NF_INET_PRE_ROUTING | 1 << NF_INET_LOCAL_IN)
	    && info->flags & XT_POLICY_MATCH_OUT) {
		printk(KERN_ERR "xt_policy: output policy not valid in "
				"PRE_ROUTING and INPUT\n");
		return false;
	}
	if (hook_mask & (1 << NF_INET_POST_ROUTING | 1 << NF_INET_LOCAL_OUT)
	    && info->flags & XT_POLICY_MATCH_IN) {
		printk(KERN_ERR "xt_policy: input policy not valid in "
				"POST_ROUTING and OUTPUT\n");
		return false;
	}
	if (info->len > XT_POLICY_MAX_ELEM) {
		printk(KERN_ERR "xt_policy: too many policy elements\n");
		return false;
	}
	return true;
}

static struct xt_match xt_policy_match[] __read_mostly = {
	{
		.name		= "policy",
		.family		= AF_INET,
		.checkentry 	= checkentry,
		.match		= match,
		.matchsize	= sizeof(struct xt_policy_info),
		.me		= THIS_MODULE,
	},
	{
		.name		= "policy",
		.family		= AF_INET6,
		.checkentry	= checkentry,
		.match		= match,
		.matchsize	= sizeof(struct xt_policy_info),
		.me		= THIS_MODULE,
	},
};

static int __init init(void)
{
	return xt_register_matches(xt_policy_match,
				   ARRAY_SIZE(xt_policy_match));
}

static void __exit fini(void)
{
	xt_unregister_matches(xt_policy_match, ARRAY_SIZE(xt_policy_match));
}

module_init(init);
module_exit(fini);
MODULE_ALIAS("ipt_policy");
MODULE_ALIAS("ip6t_policy");
Commit	Line	Data
c4b88513 PM	1	/* IP tables module for matching IPsec policy
	2	*
	3	* Copyright (c) 2004,2005 Patrick McHardy, <kaber@trash.net>
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License version 2 as
	7	* published by the Free Software Foundation.
	8	*/
	9
	10	#include <linux/kernel.h>
c4b88513 PM	11	#include <linux/module.h>
	12	#include <linux/skbuff.h>
	13	#include <linux/init.h>
	14	#include <net/xfrm.h>
	15
	16	#include <linux/netfilter/xt_policy.h>
	17	#include <linux/netfilter/x_tables.h>
	18
	19	MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
	20	MODULE_DESCRIPTION("Xtables IPsec policy matching module");
	21	MODULE_LICENSE("GPL");
	22
1d93a9cb	23	static inline bool
c4b88513 PM	24	xt_addr_cmp(const union xt_policy_addr a1, const union xt_policy_addr m,
	25	const union xt_policy_addr *a2, unsigned short family)
	26	{
	27	switch (family) {
	28	case AF_INET:
81fbfd69	29	return !((a1->a4.s_addr ^ a2->a4.s_addr) & m->a4.s_addr);
c4b88513	30	case AF_INET6:
81fbfd69	31	return !ipv6_masked_addr_cmp(&a1->a6, &m->a6, &a2->a6);
c4b88513	32	}
1d93a9cb	33	return false;
c4b88513 PM	34	}
c4b88513 PM	35
1d93a9cb	36	static inline bool
a47362a2	37	match_xfrm_state(const struct xfrm_state x, const struct xt_policy_elem e,
c4b88513 PM	38	unsigned short family)
	39	{
	40	#define MATCH_ADDR(x,y,z) (!e->match.x \|\| \
	41	(xt_addr_cmp(&e->x, &e->y, z, family) \
	42	^ e->invert.x))
	43	#define MATCH(x,y) (!e->match.x \|\| ((e->x == (y)) ^ e->invert.x))
	44
	45	return MATCH_ADDR(saddr, smask, (union xt_policy_addr *)&x->props.saddr) &&
81fbfd69	46	MATCH_ADDR(daddr, dmask, (union xt_policy_addr *)&x->id.daddr) &&
c4b88513 PM	47	MATCH(proto, x->id.proto) &&
	48	MATCH(mode, x->props.mode) &&
	49	MATCH(spi, x->id.spi) &&
	50	MATCH(reqid, x->props.reqid);
	51	}
	52
	53	static int
	54	match_policy_in(const struct sk_buff skb, const struct xt_policy_info info,
	55	unsigned short family)
	56	{
	57	const struct xt_policy_elem *e;
a47362a2	58	const struct sec_path *sp = skb->sp;
c4b88513 PM	59	int strict = info->flags & XT_POLICY_MATCH_STRICT;
	60	int i, pos;
	61
	62	if (sp == NULL)
	63	return -1;
	64	if (strict && info->len != sp->len)
	65	return 0;
	66
	67	for (i = sp->len - 1; i >= 0; i--) {
	68	pos = strict ? i - sp->len + 1 : 0;
	69	if (pos >= info->len)
	70	return 0;
	71	e = &info->pol[pos];
	72
dbe5b4aa	73	if (match_xfrm_state(sp->xvec[i], e, family)) {
c4b88513 PM	74	if (!strict)
	75	return 1;
	76	} else if (strict)
	77	return 0;
	78	}
	79
	80	return strict ? 1 : 0;
	81	}
	82
	83	static int
	84	match_policy_out(const struct sk_buff skb, const struct xt_policy_info info,
	85	unsigned short family)
	86	{
	87	const struct xt_policy_elem *e;
a47362a2	88	const struct dst_entry *dst = skb->dst;
c4b88513 PM	89	int strict = info->flags & XT_POLICY_MATCH_STRICT;
	90	int i, pos;
	91
	92	if (dst->xfrm == NULL)
	93	return -1;
	94
	95	for (i = 0; dst && dst->xfrm; dst = dst->child, i++) {
	96	pos = strict ? i : 0;
	97	if (pos >= info->len)
	98	return 0;
	99	e = &info->pol[pos];
	100
	101	if (match_xfrm_state(dst->xfrm, e, family)) {
	102	if (!strict)
	103	return 1;
	104	} else if (strict)
	105	return 0;
	106	}
	107
	108	return strict ? i == info->len : 0;
	109	}
	110
1d93a9cb JE	111	static bool match(const struct sk_buff *skb,
	112	const struct net_device *in,
	113	const struct net_device *out,
	114	const struct xt_match *match,
	115	const void *matchinfo,
	116	int offset,
	117	unsigned int protoff,
	118	bool *hotdrop)
c4b88513 PM	119	{
	120	const struct xt_policy_info *info = matchinfo;
	121	int ret;
	122
	123	if (info->flags & XT_POLICY_MATCH_IN)
	124	ret = match_policy_in(skb, info, match->family);
	125	else
	126	ret = match_policy_out(skb, info, match->family);
	127
	128	if (ret < 0)
1d93a9cb	129	ret = info->flags & XT_POLICY_MATCH_NONE ? true : false;
c4b88513	130	else if (info->flags & XT_POLICY_MATCH_NONE)
1d93a9cb	131	ret = false;
c4b88513 PM	132
	133	return ret;
	134	}
	135
ccb79bdc JE	136	static bool checkentry(const char tablename, const void ip_void,
	137	const struct xt_match *match,
	138	void *matchinfo, unsigned int hook_mask)
c4b88513 PM	139	{
	140	struct xt_policy_info *info = matchinfo;
	141
	142	if (!(info->flags & (XT_POLICY_MATCH_IN\|XT_POLICY_MATCH_OUT))) {
	143	printk(KERN_ERR "xt_policy: neither incoming nor "
601e68e1	144	"outgoing policy selected\n");
ccb79bdc	145	return false;
c4b88513	146	}
6e23ae2a	147	if (hook_mask & (1 << NF_INET_PRE_ROUTING \| 1 << NF_INET_LOCAL_IN)
c4b88513 PM	148	&& info->flags & XT_POLICY_MATCH_OUT) {
c4b88513 PM	149	printk(KERN_ERR "xt_policy: output policy not valid in "
601e68e1	150	"PRE_ROUTING and INPUT\n");
ccb79bdc	151	return false;
c4b88513	152	}
6e23ae2a	153	if (hook_mask & (1 << NF_INET_POST_ROUTING \| 1 << NF_INET_LOCAL_OUT)
c4b88513 PM	154	&& info->flags & XT_POLICY_MATCH_IN) {
c4b88513 PM	155	printk(KERN_ERR "xt_policy: input policy not valid in "
601e68e1	156	"POST_ROUTING and OUTPUT\n");
ccb79bdc	157	return false;
c4b88513 PM	158	}
	159	if (info->len > XT_POLICY_MAX_ELEM) {
	160	printk(KERN_ERR "xt_policy: too many policy elements\n");
ccb79bdc	161	return false;
c4b88513	162	}
ccb79bdc	163	return true;
c4b88513 PM	164	}
c4b88513 PM	165
9f15c530	166	static struct xt_match xt_policy_match[] __read_mostly = {
4470bbc7 PM	167	{
	168	.name = "policy",
	169	.family = AF_INET,
	170	.checkentry = checkentry,
	171	.match = match,
	172	.matchsize = sizeof(struct xt_policy_info),
4470bbc7 PM	173	.me = THIS_MODULE,
	174	},
	175	{
	176	.name = "policy",
	177	.family = AF_INET6,
	178	.checkentry = checkentry,
	179	.match = match,
	180	.matchsize = sizeof(struct xt_policy_info),
4470bbc7 PM	181	.me = THIS_MODULE,
4470bbc7 PM	182	},
c4b88513 PM	183	};
	184
	185	static int __init init(void)
	186	{
4470bbc7 PM	187	return xt_register_matches(xt_policy_match,
4470bbc7 PM	188	ARRAY_SIZE(xt_policy_match));
c4b88513 PM	189	}
	190
	191	static void __exit fini(void)
	192	{
4470bbc7	193	xt_unregister_matches(xt_policy_match, ARRAY_SIZE(xt_policy_match));
c4b88513 PM	194	}
	195
	196	module_init(init);
	197	module_exit(fini);
	198	MODULE_ALIAS("ipt_policy");
	199	MODULE_ALIAS("ip6t_policy");