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- /* 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 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->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;
- 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 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 xt_policy_match[] = {
- {
- .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");
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