![Jörn Engel](/assets/img/avatar_default.png)
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
211 lines
5.3 KiB
C
211 lines
5.3 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/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/xt_policy.h>
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#include <linux/netfilter/x_tables.h>
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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MODULE_DESCRIPTION("Xtables IPsec policy matching module");
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MODULE_LICENSE("GPL");
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static inline int
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xt_addr_cmp(const union xt_policy_addr *a1, const union xt_policy_addr *m,
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const union xt_policy_addr *a2, unsigned short family)
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{
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switch (family) {
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case AF_INET:
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return !((a1->a4.s_addr ^ a2->a4.s_addr) & m->a4.s_addr);
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case AF_INET6:
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return !ipv6_masked_addr_cmp(&a1->a6, &m->a6, &a2->a6);
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}
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return 0;
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}
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static inline int
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match_xfrm_state(struct xfrm_state *x, const struct xt_policy_elem *e,
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unsigned short family)
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{
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#define MATCH_ADDR(x,y,z) (!e->match.x || \
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(xt_addr_cmp(&e->x, &e->y, z, family) \
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^ e->invert.x))
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#define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x))
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return MATCH_ADDR(saddr, smask, (union xt_policy_addr *)&x->props.saddr) &&
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MATCH_ADDR(daddr, dmask, (union xt_policy_addr *)&x->id.daddr) &&
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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 xt_policy_info *info,
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unsigned short family)
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{
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const struct xt_policy_elem *e;
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struct sec_path *sp = skb->sp;
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int strict = info->flags & XT_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->xvec[i], e, family)) {
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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 xt_policy_info *info,
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unsigned short family)
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{
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const struct xt_policy_elem *e;
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struct dst_entry *dst = skb->dst;
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int strict = info->flags & XT_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, family)) {
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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 ? i == info->len : 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 struct xt_match *match,
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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 xt_policy_info *info = matchinfo;
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int ret;
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if (info->flags & XT_POLICY_MATCH_IN)
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ret = match_policy_in(skb, info, match->family);
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else
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ret = match_policy_out(skb, info, match->family);
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if (ret < 0)
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ret = info->flags & XT_POLICY_MATCH_NONE ? 1 : 0;
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else if (info->flags & XT_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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const struct xt_match *match,
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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 xt_policy_info *info = matchinfo;
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if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT))) {
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printk(KERN_ERR "xt_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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/* hook values are equal for IPv4 and IPv6 */
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if (hook_mask & (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_LOCAL_IN)
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&& info->flags & XT_POLICY_MATCH_OUT) {
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printk(KERN_ERR "xt_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 & XT_POLICY_MATCH_IN) {
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printk(KERN_ERR "xt_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 > XT_POLICY_MAX_ELEM) {
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printk(KERN_ERR "xt_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 xt_match policy_match = {
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.name = "policy",
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.family = AF_INET,
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.match = match,
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.matchsize = sizeof(struct xt_policy_info),
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.checkentry = checkentry,
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.family = AF_INET,
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.me = THIS_MODULE,
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};
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static struct xt_match policy6_match = {
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.name = "policy",
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.family = AF_INET6,
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.match = match,
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.matchsize = sizeof(struct xt_policy_info),
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.checkentry = checkentry,
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.family = AF_INET6,
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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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int ret;
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ret = xt_register_match(&policy_match);
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if (ret)
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return ret;
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ret = xt_register_match(&policy6_match);
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if (ret)
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xt_unregister_match(&policy_match);
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return ret;
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}
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static void __exit fini(void)
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{
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xt_unregister_match(&policy6_match);
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xt_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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MODULE_ALIAS("ipt_policy");
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MODULE_ALIAS("ip6t_policy");
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