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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; 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
112static bool
113policy_mt(const struct sk_buff *skb, struct xt_action_param *par)
114{
115 const struct xt_policy_info *info = par->matchinfo;
116 int ret;
117
118 if (info->flags & XT_POLICY_MATCH_IN)
119 ret = match_policy_in(skb, info, xt_family(par));
120 else
121 ret = match_policy_out(skb, info, xt_family(par));
122
123 if (ret < 0)
124 ret = info->flags & XT_POLICY_MATCH_NONE ? true : false;
125 else if (info->flags & XT_POLICY_MATCH_NONE)
126 ret = false;
127
128 return ret;
129}
130
131static int policy_mt_check(const struct xt_mtchk_param *par)
132{
133 const struct xt_policy_info *info = par->matchinfo;
134
135 if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT))) {
136 pr_info("neither incoming nor outgoing policy selected\n");
137 return -EINVAL;
138 }
139 if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
140 (1 << NF_INET_LOCAL_IN)) && info->flags & XT_POLICY_MATCH_OUT) {
141 pr_info("output policy not valid in PREROUTING and INPUT\n");
142 return -EINVAL;
143 }
144 if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
145 (1 << NF_INET_LOCAL_OUT)) && info->flags & XT_POLICY_MATCH_IN) {
146 pr_info("input policy not valid in POSTROUTING and OUTPUT\n");
147 return -EINVAL;
148 }
149 if (info->len > XT_POLICY_MAX_ELEM) {
150 pr_info("too many policy elements\n");
151 return -EINVAL;
152 }
153 return 0;
154}
155
156static struct xt_match policy_mt_reg[] __read_mostly = {
157 {
158 .name = "policy",
159 .family = NFPROTO_IPV4,
160 .checkentry = policy_mt_check,
161 .match = policy_mt,
162 .matchsize = sizeof(struct xt_policy_info),
163 .me = THIS_MODULE,
164 },
165 {
166 .name = "policy",
167 .family = NFPROTO_IPV6,
168 .checkentry = policy_mt_check,
169 .match = policy_mt,
170 .matchsize = sizeof(struct xt_policy_info),
171 .me = THIS_MODULE,
172 },
173};
174
175static int __init policy_mt_init(void)
176{
177 return xt_register_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
178}
179
180static void __exit policy_mt_exit(void)
181{
182 xt_unregister_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
183}
184
185module_init(policy_mt_init);
186module_exit(policy_mt_exit);
187MODULE_ALIAS("ipt_policy");
188MODULE_ALIAS("ip6t_policy");
189
