174 lines
4.2 KiB
C
174 lines
4.2 KiB
C
/* IP tables module for matching IPsec policy
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*
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* Copyright (c) 2004,2005 Patrick McHardy, <kaber@trash.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/init.h>
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#include <net/xfrm.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ipt_policy.h>
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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MODULE_DESCRIPTION("IPtables IPsec policy matching module");
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MODULE_LICENSE("GPL");
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static inline int
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match_xfrm_state(struct xfrm_state *x, const struct ipt_policy_elem *e)
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{
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#define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x))
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return MATCH(saddr, x->props.saddr.a4 & e->smask) &&
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MATCH(daddr, x->id.daddr.a4 & e->dmask) &&
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MATCH(proto, x->id.proto) &&
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MATCH(mode, x->props.mode) &&
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MATCH(spi, x->id.spi) &&
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MATCH(reqid, x->props.reqid);
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}
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static int
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match_policy_in(const struct sk_buff *skb, const struct ipt_policy_info *info)
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{
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const struct ipt_policy_elem *e;
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struct sec_path *sp = skb->sp;
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int strict = info->flags & IPT_POLICY_MATCH_STRICT;
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int i, pos;
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if (sp == NULL)
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return -1;
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if (strict && info->len != sp->len)
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return 0;
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for (i = sp->len - 1; i >= 0; i--) {
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pos = strict ? i - sp->len + 1 : 0;
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if (pos >= info->len)
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return 0;
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e = &info->pol[pos];
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if (match_xfrm_state(sp->x[i].xvec, e)) {
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if (!strict)
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return 1;
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} else if (strict)
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return 0;
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}
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return strict ? 1 : 0;
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}
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static int
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match_policy_out(const struct sk_buff *skb, const struct ipt_policy_info *info)
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{
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const struct ipt_policy_elem *e;
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struct dst_entry *dst = skb->dst;
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int strict = info->flags & IPT_POLICY_MATCH_STRICT;
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int i, pos;
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if (dst->xfrm == NULL)
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return -1;
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for (i = 0; dst && dst->xfrm; dst = dst->child, i++) {
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pos = strict ? i : 0;
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if (pos >= info->len)
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return 0;
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e = &info->pol[pos];
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if (match_xfrm_state(dst->xfrm, e)) {
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if (!strict)
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return 1;
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} else if (strict)
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return 0;
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}
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return strict ? 1 : 0;
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}
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static int match(const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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const void *matchinfo,
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int offset,
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unsigned int protoff,
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int *hotdrop)
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{
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const struct ipt_policy_info *info = matchinfo;
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int ret;
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if (info->flags & IPT_POLICY_MATCH_IN)
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ret = match_policy_in(skb, info);
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else
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ret = match_policy_out(skb, info);
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if (ret < 0)
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ret = info->flags & IPT_POLICY_MATCH_NONE ? 1 : 0;
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else if (info->flags & IPT_POLICY_MATCH_NONE)
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ret = 0;
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return ret;
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}
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static int checkentry(const char *tablename, const void *ip_void,
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void *matchinfo, unsigned int matchsize,
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unsigned int hook_mask)
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{
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struct ipt_policy_info *info = matchinfo;
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if (matchsize != IPT_ALIGN(sizeof(*info))) {
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printk(KERN_ERR "ipt_policy: matchsize %u != %zu\n",
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matchsize, IPT_ALIGN(sizeof(*info)));
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return 0;
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}
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if (!(info->flags & (IPT_POLICY_MATCH_IN|IPT_POLICY_MATCH_OUT))) {
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printk(KERN_ERR "ipt_policy: neither incoming nor "
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"outgoing policy selected\n");
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return 0;
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}
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if (hook_mask & (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_LOCAL_IN)
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&& info->flags & IPT_POLICY_MATCH_OUT) {
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printk(KERN_ERR "ipt_policy: output policy not valid in "
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"PRE_ROUTING and INPUT\n");
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return 0;
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}
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if (hook_mask & (1 << NF_IP_POST_ROUTING | 1 << NF_IP_LOCAL_OUT)
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&& info->flags & IPT_POLICY_MATCH_IN) {
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printk(KERN_ERR "ipt_policy: input policy not valid in "
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"POST_ROUTING and OUTPUT\n");
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return 0;
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}
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if (info->len > IPT_POLICY_MAX_ELEM) {
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printk(KERN_ERR "ipt_policy: too many policy elements\n");
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return 0;
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}
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return 1;
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}
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static struct ipt_match policy_match = {
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.name = "policy",
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.match = match,
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.checkentry = checkentry,
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.me = THIS_MODULE,
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};
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static int __init init(void)
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{
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return ipt_register_match(&policy_match);
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}
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static void __exit fini(void)
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{
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ipt_unregister_match(&policy_match);
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}
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module_init(init);
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module_exit(fini);
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