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Patrick McHardyc4b88512006-03-20 18:03:40 -08001/* 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 */
Jan Engelhardt8bee4ba2010-03-17 16:04:40 +01009#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
Patrick McHardyc4b88512006-03-20 18:03:40 -080010#include <linux/kernel.h>
Patrick McHardyc4b88512006-03-20 18:03:40 -080011#include <linux/module.h>
12#include <linux/skbuff.h>
13#include <linux/init.h>
14#include <net/xfrm.h>
15
Jan Engelhardt917b6fb2008-01-14 23:42:06 -080016#include <linux/netfilter.h>
Patrick McHardyc4b88512006-03-20 18:03:40 -080017#include <linux/netfilter/xt_policy.h>
18#include <linux/netfilter/x_tables.h>
19
20MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
Jan Engelhardt2ae15b62008-01-14 23:42:28 -080021MODULE_DESCRIPTION("Xtables: IPsec policy match");
Patrick McHardyc4b88512006-03-20 18:03:40 -080022MODULE_LICENSE("GPL");
23
Jan Engelhardt1d93a9c2007-07-07 22:15:35 -070024static inline bool
Jan Engelhardt917b6fb2008-01-14 23:42:06 -080025xt_addr_cmp(const union nf_inet_addr *a1, const union nf_inet_addr *m,
26 const union nf_inet_addr *a2, unsigned short family)
Patrick McHardyc4b88512006-03-20 18:03:40 -080027{
28 switch (family) {
Jan Engelhardtee999d82008-10-08 11:35:01 +020029 case NFPROTO_IPV4:
Jan Engelhardt917b6fb2008-01-14 23:42:06 -080030 return ((a1->ip ^ a2->ip) & m->ip) == 0;
Jan Engelhardtee999d82008-10-08 11:35:01 +020031 case NFPROTO_IPV6:
Jan Engelhardt917b6fb2008-01-14 23:42:06 -080032 return ipv6_masked_addr_cmp(&a1->in6, &m->in6, &a2->in6) == 0;
Patrick McHardyc4b88512006-03-20 18:03:40 -080033 }
Jan Engelhardt1d93a9c2007-07-07 22:15:35 -070034 return false;
Patrick McHardyc4b88512006-03-20 18:03:40 -080035}
36
Ilpo Järvinenb9aed452008-01-12 21:26:31 -080037static bool
Jan Engelhardta47362a2007-07-07 22:16:55 -070038match_xfrm_state(const struct xfrm_state *x, const struct xt_policy_elem *e,
Patrick McHardyc4b88512006-03-20 18:03:40 -080039 unsigned short family)
40{
41#define MATCH_ADDR(x,y,z) (!e->match.x || \
Jan Engelhardt917b6fb2008-01-14 23:42:06 -080042 (xt_addr_cmp(&e->x, &e->y, (const union nf_inet_addr *)(z), family) \
Patrick McHardyc4b88512006-03-20 18:03:40 -080043 ^ e->invert.x))
44#define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x))
45
Jan Engelhardt917b6fb2008-01-14 23:42:06 -080046 return MATCH_ADDR(saddr, smask, &x->props.saddr) &&
47 MATCH_ADDR(daddr, dmask, &x->id.daddr) &&
Patrick McHardyc4b88512006-03-20 18:03:40 -080048 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
54static int
55match_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;
Jan Engelhardta47362a2007-07-07 22:16:55 -070059 const struct sec_path *sp = skb->sp;
Patrick McHardyc4b88512006-03-20 18:03:40 -080060 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
Herbert Xudbe5b4a2006-04-01 00:54:16 -080074 if (match_xfrm_state(sp->xvec[i], e, family)) {
Patrick McHardyc4b88512006-03-20 18:03:40 -080075 if (!strict)
76 return 1;
77 } else if (strict)
78 return 0;
79 }
80
81 return strict ? 1 : 0;
82}
83
84static int
85match_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;
Eric Dumazetadf30902009-06-02 05:19:30 +000089 const struct dst_entry *dst = skb_dst(skb);
Patrick McHardyc4b88512006-03-20 18:03:40 -080090 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
Jan Engelhardtd3c5ee62007-12-04 23:24:03 -0800112static bool
Jan Engelhardt62fc8052009-07-07 20:42:08 +0200113policy_mt(const struct sk_buff *skb, struct xt_action_param *par)
Patrick McHardyc4b88512006-03-20 18:03:40 -0800114{
Jan Engelhardtf7108a22008-10-08 11:35:18 +0200115 const struct xt_policy_info *info = par->matchinfo;
Patrick McHardyc4b88512006-03-20 18:03:40 -0800116 int ret;
117
118 if (info->flags & XT_POLICY_MATCH_IN)
Jan Engelhardtaa5fa312010-03-18 00:44:52 +0100119 ret = match_policy_in(skb, info, par->family);
Patrick McHardyc4b88512006-03-20 18:03:40 -0800120 else
Jan Engelhardtaa5fa312010-03-18 00:44:52 +0100121 ret = match_policy_out(skb, info, par->family);
Patrick McHardyc4b88512006-03-20 18:03:40 -0800122
123 if (ret < 0)
Jan Engelhardt1d93a9c2007-07-07 22:15:35 -0700124 ret = info->flags & XT_POLICY_MATCH_NONE ? true : false;
Patrick McHardyc4b88512006-03-20 18:03:40 -0800125 else if (info->flags & XT_POLICY_MATCH_NONE)
Jan Engelhardt1d93a9c2007-07-07 22:15:35 -0700126 ret = false;
Patrick McHardyc4b88512006-03-20 18:03:40 -0800127
128 return ret;
129}
130
Jan Engelhardtb0f38452010-03-19 17:16:42 +0100131static int policy_mt_check(const struct xt_mtchk_param *par)
Patrick McHardyc4b88512006-03-20 18:03:40 -0800132{
Jan Engelhardt9b4fce72008-10-08 11:35:18 +0200133 const struct xt_policy_info *info = par->matchinfo;
Patrick McHardyc4b88512006-03-20 18:03:40 -0800134
135 if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT))) {
Jan Engelhardt8bee4ba2010-03-17 16:04:40 +0100136 pr_info("neither incoming nor outgoing policy selected\n");
Jan Engelhardtbd414ee2010-03-23 16:35:56 +0100137 return -EINVAL;
Patrick McHardyc4b88512006-03-20 18:03:40 -0800138 }
Jan Engelhardt9b4fce72008-10-08 11:35:18 +0200139 if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
140 (1 << NF_INET_LOCAL_IN)) && info->flags & XT_POLICY_MATCH_OUT) {
Jan Engelhardt8bee4ba2010-03-17 16:04:40 +0100141 pr_info("output policy not valid in PREROUTING and INPUT\n");
Jan Engelhardtbd414ee2010-03-23 16:35:56 +0100142 return -EINVAL;
Patrick McHardyc4b88512006-03-20 18:03:40 -0800143 }
Jan Engelhardt9b4fce72008-10-08 11:35:18 +0200144 if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
145 (1 << NF_INET_LOCAL_OUT)) && info->flags & XT_POLICY_MATCH_IN) {
Jan Engelhardt8bee4ba2010-03-17 16:04:40 +0100146 pr_info("input policy not valid in POSTROUTING and OUTPUT\n");
Jan Engelhardtbd414ee2010-03-23 16:35:56 +0100147 return -EINVAL;
Patrick McHardyc4b88512006-03-20 18:03:40 -0800148 }
149 if (info->len > XT_POLICY_MAX_ELEM) {
Jan Engelhardt8bee4ba2010-03-17 16:04:40 +0100150 pr_info("too many policy elements\n");
Jan Engelhardtbd414ee2010-03-23 16:35:56 +0100151 return -EINVAL;
Patrick McHardyc4b88512006-03-20 18:03:40 -0800152 }
Jan Engelhardtbd414ee2010-03-23 16:35:56 +0100153 return 0;
Patrick McHardyc4b88512006-03-20 18:03:40 -0800154}
155
Jan Engelhardtd3c5ee62007-12-04 23:24:03 -0800156static struct xt_match policy_mt_reg[] __read_mostly = {
Patrick McHardy4470bbc2006-08-22 00:34:04 -0700157 {
158 .name = "policy",
Jan Engelhardtee999d82008-10-08 11:35:01 +0200159 .family = NFPROTO_IPV4,
Jan Engelhardtd3c5ee62007-12-04 23:24:03 -0800160 .checkentry = policy_mt_check,
161 .match = policy_mt,
Patrick McHardy4470bbc2006-08-22 00:34:04 -0700162 .matchsize = sizeof(struct xt_policy_info),
Patrick McHardy4470bbc2006-08-22 00:34:04 -0700163 .me = THIS_MODULE,
164 },
165 {
166 .name = "policy",
Jan Engelhardtee999d82008-10-08 11:35:01 +0200167 .family = NFPROTO_IPV6,
Jan Engelhardtd3c5ee62007-12-04 23:24:03 -0800168 .checkentry = policy_mt_check,
169 .match = policy_mt,
Patrick McHardy4470bbc2006-08-22 00:34:04 -0700170 .matchsize = sizeof(struct xt_policy_info),
Patrick McHardy4470bbc2006-08-22 00:34:04 -0700171 .me = THIS_MODULE,
172 },
Patrick McHardyc4b88512006-03-20 18:03:40 -0800173};
174
Jan Engelhardtd3c5ee62007-12-04 23:24:03 -0800175static int __init policy_mt_init(void)
Patrick McHardyc4b88512006-03-20 18:03:40 -0800176{
Jan Engelhardtd3c5ee62007-12-04 23:24:03 -0800177 return xt_register_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
Patrick McHardyc4b88512006-03-20 18:03:40 -0800178}
179
Jan Engelhardtd3c5ee62007-12-04 23:24:03 -0800180static void __exit policy_mt_exit(void)
Patrick McHardyc4b88512006-03-20 18:03:40 -0800181{
Jan Engelhardtd3c5ee62007-12-04 23:24:03 -0800182 xt_unregister_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
Patrick McHardyc4b88512006-03-20 18:03:40 -0800183}
184
Jan Engelhardtd3c5ee62007-12-04 23:24:03 -0800185module_init(policy_mt_init);
186module_exit(policy_mt_exit);
Patrick McHardyc4b88512006-03-20 18:03:40 -0800187MODULE_ALIAS("ipt_policy");
188MODULE_ALIAS("ip6t_policy");