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0006 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0007 #include <linux/kernel.h>
0008 #include <linux/module.h>
0009 #include <linux/skbuff.h>
0010 #include <linux/init.h>
0011 #include <net/xfrm.h>
0012
0013 #include <linux/netfilter.h>
0014 #include <linux/netfilter/xt_policy.h>
0015 #include <linux/netfilter/x_tables.h>
0016
0017 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
0018 MODULE_DESCRIPTION("Xtables: IPsec policy match");
0019 MODULE_LICENSE("GPL");
0020
0021 static inline bool
0022 xt_addr_cmp(const union nf_inet_addr *a1, const union nf_inet_addr *m,
0023 const union nf_inet_addr *a2, unsigned short family)
0024 {
0025 switch (family) {
0026 case NFPROTO_IPV4:
0027 return ((a1->ip ^ a2->ip) & m->ip) == 0;
0028 case NFPROTO_IPV6:
0029 return ipv6_masked_addr_cmp(&a1->in6, &m->in6, &a2->in6) == 0;
0030 }
0031 return false;
0032 }
0033
0034 static bool
0035 match_xfrm_state(const struct xfrm_state *x, const struct xt_policy_elem *e,
0036 unsigned short family)
0037 {
0038 #define MATCH_ADDR(x,y,z) (!e->match.x || \
0039 (xt_addr_cmp(&e->x, &e->y, (const union nf_inet_addr *)(z), family) \
0040 ^ e->invert.x))
0041 #define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x))
0042
0043 return MATCH_ADDR(saddr, smask, &x->props.saddr) &&
0044 MATCH_ADDR(daddr, dmask, &x->id.daddr) &&
0045 MATCH(proto, x->id.proto) &&
0046 MATCH(mode, x->props.mode) &&
0047 MATCH(spi, x->id.spi) &&
0048 MATCH(reqid, x->props.reqid);
0049 }
0050
0051 static int
0052 match_policy_in(const struct sk_buff *skb, const struct xt_policy_info *info,
0053 unsigned short family)
0054 {
0055 const struct xt_policy_elem *e;
0056 const struct sec_path *sp = skb_sec_path(skb);
0057 int strict = info->flags & XT_POLICY_MATCH_STRICT;
0058 int i, pos;
0059
0060 if (sp == NULL)
0061 return -1;
0062 if (strict && info->len != sp->len)
0063 return 0;
0064
0065 for (i = sp->len - 1; i >= 0; i--) {
0066 pos = strict ? i - sp->len + 1 : 0;
0067 if (pos >= info->len)
0068 return 0;
0069 e = &info->pol[pos];
0070
0071 if (match_xfrm_state(sp->xvec[i], e, family)) {
0072 if (!strict)
0073 return 1;
0074 } else if (strict)
0075 return 0;
0076 }
0077
0078 return strict ? 1 : 0;
0079 }
0080
0081 static int
0082 match_policy_out(const struct sk_buff *skb, const struct xt_policy_info *info,
0083 unsigned short family)
0084 {
0085 const struct xt_policy_elem *e;
0086 const struct dst_entry *dst = skb_dst(skb);
0087 int strict = info->flags & XT_POLICY_MATCH_STRICT;
0088 int i, pos;
0089
0090 if (dst->xfrm == NULL)
0091 return -1;
0092
0093 for (i = 0; dst && dst->xfrm;
0094 dst = ((struct xfrm_dst *)dst)->child, i++) {
0095 pos = strict ? i : 0;
0096 if (pos >= info->len)
0097 return 0;
0098 e = &info->pol[pos];
0099
0100 if (match_xfrm_state(dst->xfrm, e, family)) {
0101 if (!strict)
0102 return 1;
0103 } else if (strict)
0104 return 0;
0105 }
0106
0107 return strict ? i == info->len : 0;
0108 }
0109
0110 static bool
0111 policy_mt(const struct sk_buff *skb, struct xt_action_param *par)
0112 {
0113 const struct xt_policy_info *info = par->matchinfo;
0114 int ret;
0115
0116 if (info->flags & XT_POLICY_MATCH_IN)
0117 ret = match_policy_in(skb, info, xt_family(par));
0118 else
0119 ret = match_policy_out(skb, info, xt_family(par));
0120
0121 if (ret < 0)
0122 ret = info->flags & XT_POLICY_MATCH_NONE ? true : false;
0123 else if (info->flags & XT_POLICY_MATCH_NONE)
0124 ret = false;
0125
0126 return ret;
0127 }
0128
0129 static int policy_mt_check(const struct xt_mtchk_param *par)
0130 {
0131 const struct xt_policy_info *info = par->matchinfo;
0132 const char *errmsg = "neither incoming nor outgoing policy selected";
0133
0134 if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT)))
0135 goto err;
0136
0137 if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
0138 (1 << NF_INET_LOCAL_IN)) && info->flags & XT_POLICY_MATCH_OUT) {
0139 errmsg = "output policy not valid in PREROUTING and INPUT";
0140 goto err;
0141 }
0142 if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
0143 (1 << NF_INET_LOCAL_OUT)) && info->flags & XT_POLICY_MATCH_IN) {
0144 errmsg = "input policy not valid in POSTROUTING and OUTPUT";
0145 goto err;
0146 }
0147 if (info->len > XT_POLICY_MAX_ELEM) {
0148 errmsg = "too many policy elements";
0149 goto err;
0150 }
0151 return 0;
0152 err:
0153 pr_info_ratelimited("%s\n", errmsg);
0154 return -EINVAL;
0155 }
0156
0157 static struct xt_match policy_mt_reg[] __read_mostly = {
0158 {
0159 .name = "policy",
0160 .family = NFPROTO_IPV4,
0161 .checkentry = policy_mt_check,
0162 .match = policy_mt,
0163 .matchsize = sizeof(struct xt_policy_info),
0164 .me = THIS_MODULE,
0165 },
0166 {
0167 .name = "policy",
0168 .family = NFPROTO_IPV6,
0169 .checkentry = policy_mt_check,
0170 .match = policy_mt,
0171 .matchsize = sizeof(struct xt_policy_info),
0172 .me = THIS_MODULE,
0173 },
0174 };
0175
0176 static int __init policy_mt_init(void)
0177 {
0178 return xt_register_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
0179 }
0180
0181 static void __exit policy_mt_exit(void)
0182 {
0183 xt_unregister_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg));
0184 }
0185
0186 module_init(policy_mt_init);
0187 module_exit(policy_mt_exit);
0188 MODULE_ALIAS("ipt_policy");
0189 MODULE_ALIAS("ip6t_policy");
