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*
* 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_ipv4.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_policy.h>
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_DESCRIPTION("IPtables IPsec policy matching module");
MODULE_LICENSE("GPL");
static inline int
match_xfrm_state(struct xfrm_state *x, const struct ipt_policy_elem *e)
{
#define MATCH_ADDR(x,y,z) (!e->match.x || \
((e->x.a4.s_addr == (e->y.a4.s_addr & (z))) \
^ e->invert.x))
#define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x))
return MATCH_ADDR(saddr, smask, x->props.saddr.a4) &&
MATCH_ADDR(daddr, dmask, x->id.daddr.a4) &&
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 ipt_policy_info *info)
{
const struct ipt_policy_elem *e;
struct sec_path *sp = skb->sp;
int strict = info->flags & IPT_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)) {
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 ipt_policy_info *info)
{
const struct ipt_policy_elem *e;
struct dst_entry *dst = skb->dst;
int strict = info->flags & IPT_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)) {
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 void *matchinfo,
int offset,
unsigned int protoff,
int *hotdrop)
{
const struct ipt_policy_info *info = matchinfo;
int ret;
if (info->flags & IPT_POLICY_MATCH_IN)
ret = match_policy_in(skb, info);
else
ret = match_policy_out(skb, info);
if (ret < 0)
ret = info->flags & IPT_POLICY_MATCH_NONE ? 1 : 0;
else if (info->flags & IPT_POLICY_MATCH_NONE)
ret = 0;
return ret;
}
static int checkentry(const char *tablename, const void *ip_void,
void *matchinfo, unsigned int matchsize,
unsigned int hook_mask)
{
struct ipt_policy_info *info = matchinfo;
if (matchsize != IPT_ALIGN(sizeof(*info))) {
printk(KERN_ERR "ipt_policy: matchsize %u != %zu\n",
matchsize, IPT_ALIGN(sizeof(*info)));
return 0;
}
if (!(info->flags & (IPT_POLICY_MATCH_IN|IPT_POLICY_MATCH_OUT))) {
printk(KERN_ERR "ipt_policy: neither incoming nor "
"outgoing policy selected\n");
return 0;
}
if (hook_mask & (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_LOCAL_IN)
&& info->flags & IPT_POLICY_MATCH_OUT) {
printk(KERN_ERR "ipt_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 & IPT_POLICY_MATCH_IN) {
printk(KERN_ERR "ipt_policy: input policy not valid in "
"POST_ROUTING and OUTPUT\n");
return 0;
}
if (info->len > IPT_POLICY_MAX_ELEM) {
printk(KERN_ERR "ipt_policy: too many policy elements\n");
return 0;
}
return 1;
}
static struct ipt_match policy_match = {
.name = "policy",
.match = match,
.checkentry = checkentry,
.me = THIS_MODULE,
};
static int __init init(void)
{
return ipt_register_match(&policy_match);
}
static void __exit fini(void)
{
ipt_unregister_match(&policy_match);
}
module_init(init);
module_exit(fini);
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