[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/config.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 int
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 0;
}

static inline int
match_xfrm_state(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;
	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->x[i].xvec, 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;
	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 int 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,
                 int *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 ? 1 : 0;
	else if (info->flags & XT_POLICY_MATCH_NONE)
		ret = 0;

	return ret;
}

static int checkentry(const char *tablename, const void *ip_void,
                      const struct xt_match *match,
                      void *matchinfo, unsigned int matchsize,
                      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 0;
	}
	/* hook values are equal for IPv4 and IPv6 */
	if (hook_mask & (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_LOCAL_IN)
	    && info->flags & XT_POLICY_MATCH_OUT) {
		printk(KERN_ERR "xt_policy: output policy not valid in "
		                "PRE_ROUTING and INPUT\n");
		return 0;
	}
	if (hook_mask & (1 << NF_IP_POST_ROUTING | 1 << NF_IP_LOCAL_OUT)
	    && info->flags & XT_POLICY_MATCH_IN) {
		printk(KERN_ERR "xt_policy: input policy not valid in "
		                "POST_ROUTING and OUTPUT\n");
		return 0;
	}
	if (info->len > XT_POLICY_MAX_ELEM) {
		printk(KERN_ERR "xt_policy: too many policy elements\n");
		return 0;
	}
	return 1;
}

static struct xt_match policy_match = {
	.name		= "policy",
	.family		= AF_INET,
	.match		= match,
	.matchsize	= sizeof(struct xt_policy_info),
	.checkentry 	= checkentry,
	.family		= AF_INET,
	.me		= THIS_MODULE,
};

static struct xt_match policy6_match = {
	.name		= "policy",
	.family		= AF_INET6,
	.match		= match,
	.matchsize	= sizeof(struct xt_policy_info),
	.checkentry	= checkentry,
	.family		= AF_INET6,
	.me		= THIS_MODULE,
};

static int __init init(void)
{
	int ret;

	ret = xt_register_match(&policy_match);
	if (ret)
		return ret;
	ret = xt_register_match(&policy6_match);
	if (ret)
		xt_unregister_match(&policy_match);
	return ret;
}

static void __exit fini(void)
{
	xt_unregister_match(&policy6_match);
	xt_unregister_match(&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>
	11	#include <linux/config.h>
	12	#include <linux/module.h>
	13	#include <linux/skbuff.h>
	14	#include <linux/init.h>
	15	#include <net/xfrm.h>
	16
	17	#include <linux/netfilter/xt_policy.h>
	18	#include <linux/netfilter/x_tables.h>
	19
	20	MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
	21	MODULE_DESCRIPTION("Xtables IPsec policy matching module");
	22	MODULE_LICENSE("GPL");
	23
	24	static inline int
	25	xt_addr_cmp(const union xt_policy_addr a1, const union xt_policy_addr m,
	26	const union xt_policy_addr *a2, unsigned short family)
	27	{
	28	switch (family) {
	29	case AF_INET:
81fbfd69	30	return !((a1->a4.s_addr ^ a2->a4.s_addr) & m->a4.s_addr);
c4b88513	31	case AF_INET6:
81fbfd69	32	return !ipv6_masked_addr_cmp(&a1->a6, &m->a6, &a2->a6);
c4b88513 PM	33	}
	34	return 0;
	35	}
	36
	37	static inline int
	38	match_xfrm_state(struct xfrm_state x, const struct xt_policy_elem e,
	39	unsigned short family)
	40	{
	41	#define MATCH_ADDR(x,y,z) (!e->match.x \|\| \
	42	(xt_addr_cmp(&e->x, &e->y, z, family) \
	43	^ e->invert.x))
	44	#define MATCH(x,y) (!e->match.x \|\| ((e->x == (y)) ^ e->invert.x))
	45
	46	return MATCH_ADDR(saddr, smask, (union xt_policy_addr *)&x->props.saddr) &&
81fbfd69	47	MATCH_ADDR(daddr, dmask, (union xt_policy_addr *)&x->id.daddr) &&
c4b88513 PM	48	MATCH(proto, x->id.proto) &&
	49	MATCH(mode, x->props.mode) &&
	50	MATCH(spi, x->id.spi) &&
	51	MATCH(reqid, x->props.reqid);
	52	}
	53
	54	static int
	55	match_policy_in(const struct sk_buff skb, const struct xt_policy_info info,
	56	unsigned short family)
	57	{
	58	const struct xt_policy_elem *e;
	59	struct sec_path *sp = skb->sp;
	60	int strict = info->flags & XT_POLICY_MATCH_STRICT;
	61	int i, pos;
	62
	63	if (sp == NULL)
	64	return -1;
	65	if (strict && info->len != sp->len)
	66	return 0;
	67
	68	for (i = sp->len - 1; i >= 0; i--) {
	69	pos = strict ? i - sp->len + 1 : 0;
	70	if (pos >= info->len)
	71	return 0;
	72	e = &info->pol[pos];
	73
	74	if (match_xfrm_state(sp->x[i].xvec, e, family)) {
	75	if (!strict)
	76	return 1;
	77	} else if (strict)
	78	return 0;
	79	}
	80
	81	return strict ? 1 : 0;
	82	}
	83
	84	static int
	85	match_policy_out(const struct sk_buff skb, const struct xt_policy_info info,
	86	unsigned short family)
	87	{
	88	const struct xt_policy_elem *e;
	89	struct dst_entry *dst = skb->dst;
	90	int strict = info->flags & XT_POLICY_MATCH_STRICT;
	91	int i, pos;
	92
	93	if (dst->xfrm == NULL)
	94	return -1;
	95
	96	for (i = 0; dst && dst->xfrm; dst = dst->child, i++) {
	97	pos = strict ? i : 0;
	98	if (pos >= info->len)
	99	return 0;
	100	e = &info->pol[pos];
	101
	102	if (match_xfrm_state(dst->xfrm, e, family)) {
	103	if (!strict)
	104	return 1;
	105	} else if (strict)
	106	return 0;
	107	}
	108
	109	return strict ? i == info->len : 0;
	110	}
	111
112	static int match(const struct sk_buff *skb,
113	const struct net_device *in,
114	const struct net_device *out,
115	const struct xt_match *match,
116	const void *matchinfo,
117	int offset,
118	unsigned int protoff,
119	int *hotdrop)
120	{
121	const struct xt_policy_info *info = matchinfo;
122	int ret;
123
124	if (info->flags & XT_POLICY_MATCH_IN)
125	ret = match_policy_in(skb, info, match->family);
126	else
127	ret = match_policy_out(skb, info, match->family);
128
129	if (ret < 0)
130	ret = info->flags & XT_POLICY_MATCH_NONE ? 1 : 0;
131	else if (info->flags & XT_POLICY_MATCH_NONE)
132	ret = 0;
133
134	return ret;
135	}
136
137	static int checkentry(const char tablename, const void ip_void,
138	const struct xt_match *match,
139	void *matchinfo, unsigned int matchsize,
140	unsigned int hook_mask)
141	{
142	struct xt_policy_info *info = matchinfo;
143
144	if (!(info->flags & (XT_POLICY_MATCH_IN\|XT_POLICY_MATCH_OUT))) {
145	printk(KERN_ERR "xt_policy: neither incoming nor "
146	"outgoing policy selected\n");
147	return 0;
148	}
149	/* hook values are equal for IPv4 and IPv6 */
150	if (hook_mask & (1 << NF_IP_PRE_ROUTING \| 1 << NF_IP_LOCAL_IN)
151	&& info->flags & XT_POLICY_MATCH_OUT) {
152	printk(KERN_ERR "xt_policy: output policy not valid in "
153	"PRE_ROUTING and INPUT\n");
154	return 0;
155	}
156	if (hook_mask & (1 << NF_IP_POST_ROUTING \| 1 << NF_IP_LOCAL_OUT)
157	&& info->flags & XT_POLICY_MATCH_IN) {
158	printk(KERN_ERR "xt_policy: input policy not valid in "
159	"POST_ROUTING and OUTPUT\n");
160	return 0;
161	}
162	if (info->len > XT_POLICY_MAX_ELEM) {
163	printk(KERN_ERR "xt_policy: too many policy elements\n");
164	return 0;
165	}
166	return 1;
167	}
168
169	static struct xt_match policy_match = {
170	.name = "policy",
171	.family = AF_INET,
172	.match = match,
173	.matchsize = sizeof(struct xt_policy_info),
174	.checkentry = checkentry,
a45049c5	175	.family = AF_INET,
c4b88513 PM	176	.me = THIS_MODULE,
	177	};
	178
	179	static struct xt_match policy6_match = {
	180	.name = "policy",
	181	.family = AF_INET6,
	182	.match = match,
	183	.matchsize = sizeof(struct xt_policy_info),
	184	.checkentry = checkentry,
a45049c5	185	.family = AF_INET6,
c4b88513 PM	186	.me = THIS_MODULE,
	187	};
	188
	189	static int __init init(void)
	190	{
	191	int ret;
	192
a45049c5	193	ret = xt_register_match(&policy_match);
c4b88513 PM	194	if (ret)
c4b88513 PM	195	return ret;
a45049c5	196	ret = xt_register_match(&policy6_match);
c4b88513	197	if (ret)
a45049c5	198	xt_unregister_match(&policy_match);
c4b88513 PM	199	return ret;
	200	}
	201
	202	static void __exit fini(void)
	203	{
a45049c5 PNA	204	xt_unregister_match(&policy6_match);
a45049c5 PNA	205	xt_unregister_match(&policy_match);
c4b88513 PM	206	}
	207
	208	module_init(init);
	209	module_exit(fini);
	210	MODULE_ALIAS("ipt_policy");
	211	MODULE_ALIAS("ip6t_policy");