1
2
3
4
5
6
7
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/skbuff.h>
13#include <linux/init.h>
14#include <net/xfrm.h>
15
16#include <linux/netfilter.h>
17#include <linux/netfilter/xt_policy.h>
18#include <linux/netfilter/x_tables.h>
19
20MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
21MODULE_DESCRIPTION("Xtables: IPsec policy match");
22MODULE_LICENSE("GPL");
23
24static inline bool
25xt_addr_cmp(const union nf_inet_addr *a1, const union nf_inet_addr *m,
26 const union nf_inet_addr *a2, unsigned short family)
27{
28 switch (family) {
29 case NFPROTO_IPV4:
30 return ((a1->ip ^ a2->ip) & m->ip) == 0;
31 case NFPROTO_IPV6:
32 return ipv6_masked_addr_cmp(&a1->in6, &m->in6, &a2->in6) == 0;
33 }
34 return false;
35}
36
37static bool
38match_xfrm_state(const struct xfrm_state *x, const struct xt_policy_elem *e,
39 unsigned short family)
40{
41#define MATCH_ADDR(x,y,z) (!e->match.x || \
42 (xt_addr_cmp(&e->x, &e->y, (const union nf_inet_addr *)(z), family) \
43 ^ e->invert.x))
44#define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x))
45
46 return MATCH_ADDR(saddr, smask, &x->props.saddr) &&
47 MATCH_ADDR(daddr, dmask, &x->id.daddr) &&
48 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;
59 const struct sec_path *sp = skb->sp;
60 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
74 if (match_xfrm_state(sp->xvec[i], e, family)) {
75 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;
89 const struct dst_entry *dst = skb_dst(skb);
90 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;
97 dst = ((struct xfrm_dst *)dst)->child, i++) {
98 pos = strict ? i : 0;
99 if (pos >= info->len)
100 return 0;
101 e = &info->pol[pos];
102
103 if (match_xfrm_state(dst->xfrm, e, family)) {
104 if (!strict)
105 return 1;
106 } else if (strict)
107 return 0;
108 }
109
110 return strict ? i == info->len : 0;
111}
112
113static bool
114policy_mt(const struct sk_buff *skb, struct xt_action_param *par)
115{
116 const struct xt_policy_info *info = par->matchinfo;
117 int ret;
118
119 if (info->flags & XT_POLICY_MATCH_IN)
120 ret = match_policy_in(skb, info, xt_family(par));
121 else
122 ret = match_policy_out(skb, info, xt_family(par));
123
124 if (ret < 0)
125 ret = info->flags & XT_POLICY_MATCH_NONE ? true : false;
126 else if (info->flags & XT_POLICY_MATCH_NONE)
127 ret = false;
128
129 return ret;
130}
131
132static int policy_mt_check(const struct xt_mtchk_param *par)
133{
134 const struct xt_policy_info *info = par->matchinfo;
135 const char *errmsg = "neither incoming nor outgoing policy selected";
136
137 if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT)))
138 goto err;
139
140 if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
141 (1 << NF_INET_LOCAL_IN)) && info->flags & XT_POLICY_MATCH_OUT) {
142 errmsg = "output policy not valid in PREROUTING and INPUT";
143 goto err;
144 }
145 if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
146 (1 << NF_INET_LOCAL_OUT)) && info->flags & XT_POLICY_MATCH_IN) {
147 errmsg = "input policy not valid in POSTROUTING and OUTPUT";
148 goto err;
149 }
150 if (info->len > XT_POLICY_MAX_ELEM) {
151 errmsg = "too many policy elements";
152 goto err;
153 }
154 return 0;
155err:
156 pr_info_ratelimited("%s\n", errmsg);
157 return -EINVAL;
158}
159
160static struct xt_match policy_mt_reg[] __read_mostly = {
161 {
162 .name = "policy",
163 .family = NFPROTO_IPV4,
164 .checkentry = policy_mt_check,
165 .match = policy_mt,
166 .matchsize = sizeof(struct xt_policy_info),
167 .me = THIS_MODULE,
168 },
169 {
170 .name = "policy",
171 .family = NFPROTO_IPV6,
172 .checkentry = policy_mt_check,
173 .match = policy_mt,
174 .matchsize = sizeof(struct xt_policy_info),
175 .me = THIS_MODULE,
176 },
177};
178
179static int __init policy_mt_init(void)
180{
181 return xt_register_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
182}
183
184static void __exit policy_mt_exit(void)
185{
186 xt_unregister_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
187}
188
189module_init(policy_mt_init);
190module_exit(policy_mt_exit);
191MODULE_ALIAS("ipt_policy");
192MODULE_ALIAS("ip6t_policy");
193
