Patrick McHardy | c4b8851 | 2006-03-20 18:03:40 -0800 | [diff] [blame] | 1 | /* 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 | */ |
| 9 | |
| 10 | #include <linux/kernel.h> |
| 11 | #include <linux/config.h> |
| 12 | #include <linux/module.h> |
| 13 | #include <linux/skbuff.h> |
| 14 | #include <linux/init.h> |
| 15 | #include <net/xfrm.h> |
| 16 | |
| 17 | #include <linux/netfilter/xt_policy.h> |
| 18 | #include <linux/netfilter/x_tables.h> |
| 19 | |
| 20 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); |
| 21 | MODULE_DESCRIPTION("Xtables IPsec policy matching module"); |
| 22 | MODULE_LICENSE("GPL"); |
| 23 | |
| 24 | static inline int |
| 25 | xt_addr_cmp(const union xt_policy_addr *a1, const union xt_policy_addr *m, |
| 26 | const union xt_policy_addr *a2, unsigned short family) |
| 27 | { |
| 28 | switch (family) { |
| 29 | case AF_INET: |
Patrick McHardy | 81fbfd6 | 2006-03-22 13:56:33 -0800 | [diff] [blame] | 30 | return !((a1->a4.s_addr ^ a2->a4.s_addr) & m->a4.s_addr); |
Patrick McHardy | c4b8851 | 2006-03-20 18:03:40 -0800 | [diff] [blame] | 31 | case AF_INET6: |
Patrick McHardy | 81fbfd6 | 2006-03-22 13:56:33 -0800 | [diff] [blame] | 32 | return !ipv6_masked_addr_cmp(&a1->a6, &m->a6, &a2->a6); |
Patrick McHardy | c4b8851 | 2006-03-20 18:03:40 -0800 | [diff] [blame] | 33 | } |
| 34 | return 0; |
| 35 | } |
| 36 | |
| 37 | static inline int |
| 38 | match_xfrm_state(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, 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, (union xt_policy_addr *)&x->props.saddr) && |
Patrick McHardy | 81fbfd6 | 2006-03-22 13:56:33 -0800 | [diff] [blame] | 47 | MATCH_ADDR(daddr, dmask, (union xt_policy_addr *)&x->id.daddr) && |
Patrick McHardy | c4b8851 | 2006-03-20 18:03:40 -0800 | [diff] [blame] | 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 | |
| 54 | static int |
| 55 | match_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 | 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->x[i].xvec, e, family)) { |
| 75 | if (!strict) |
| 76 | return 1; |
| 77 | } else if (strict) |
| 78 | return 0; |
| 79 | } |
| 80 | |
| 81 | return strict ? 1 : 0; |
| 82 | } |
| 83 | |
| 84 | static int |
| 85 | match_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 | struct dst_entry *dst = skb->dst; |
| 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 | |
| 112 | static int match(const struct sk_buff *skb, |
| 113 | const struct net_device *in, |
| 114 | const struct net_device *out, |
| 115 | const struct xt_match *match, |
| 116 | const void *matchinfo, |
| 117 | int offset, |
| 118 | unsigned int protoff, |
| 119 | int *hotdrop) |
| 120 | { |
| 121 | const struct xt_policy_info *info = matchinfo; |
| 122 | int ret; |
| 123 | |
| 124 | if (info->flags & XT_POLICY_MATCH_IN) |
| 125 | ret = match_policy_in(skb, info, match->family); |
| 126 | else |
| 127 | ret = match_policy_out(skb, info, match->family); |
| 128 | |
| 129 | if (ret < 0) |
| 130 | ret = info->flags & XT_POLICY_MATCH_NONE ? 1 : 0; |
| 131 | else if (info->flags & XT_POLICY_MATCH_NONE) |
| 132 | ret = 0; |
| 133 | |
| 134 | return ret; |
| 135 | } |
| 136 | |
| 137 | static int checkentry(const char *tablename, const void *ip_void, |
| 138 | const struct xt_match *match, |
| 139 | void *matchinfo, unsigned int matchsize, |
| 140 | unsigned int hook_mask) |
| 141 | { |
| 142 | struct xt_policy_info *info = matchinfo; |
| 143 | |
| 144 | if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT))) { |
| 145 | printk(KERN_ERR "xt_policy: neither incoming nor " |
| 146 | "outgoing policy selected\n"); |
| 147 | return 0; |
| 148 | } |
| 149 | /* hook values are equal for IPv4 and IPv6 */ |
| 150 | if (hook_mask & (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_LOCAL_IN) |
| 151 | && info->flags & XT_POLICY_MATCH_OUT) { |
| 152 | printk(KERN_ERR "xt_policy: output policy not valid in " |
| 153 | "PRE_ROUTING and INPUT\n"); |
| 154 | return 0; |
| 155 | } |
| 156 | if (hook_mask & (1 << NF_IP_POST_ROUTING | 1 << NF_IP_LOCAL_OUT) |
| 157 | && info->flags & XT_POLICY_MATCH_IN) { |
| 158 | printk(KERN_ERR "xt_policy: input policy not valid in " |
| 159 | "POST_ROUTING and OUTPUT\n"); |
| 160 | return 0; |
| 161 | } |
| 162 | if (info->len > XT_POLICY_MAX_ELEM) { |
| 163 | printk(KERN_ERR "xt_policy: too many policy elements\n"); |
| 164 | return 0; |
| 165 | } |
| 166 | return 1; |
| 167 | } |
| 168 | |
| 169 | static struct xt_match policy_match = { |
| 170 | .name = "policy", |
| 171 | .family = AF_INET, |
| 172 | .match = match, |
| 173 | .matchsize = sizeof(struct xt_policy_info), |
| 174 | .checkentry = checkentry, |
Pablo Neira Ayuso | a45049c | 2006-03-22 13:55:40 -0800 | [diff] [blame] | 175 | .family = AF_INET, |
Patrick McHardy | c4b8851 | 2006-03-20 18:03:40 -0800 | [diff] [blame] | 176 | .me = THIS_MODULE, |
| 177 | }; |
| 178 | |
| 179 | static struct xt_match policy6_match = { |
| 180 | .name = "policy", |
| 181 | .family = AF_INET6, |
| 182 | .match = match, |
| 183 | .matchsize = sizeof(struct xt_policy_info), |
| 184 | .checkentry = checkentry, |
Pablo Neira Ayuso | a45049c | 2006-03-22 13:55:40 -0800 | [diff] [blame] | 185 | .family = AF_INET6, |
Patrick McHardy | c4b8851 | 2006-03-20 18:03:40 -0800 | [diff] [blame] | 186 | .me = THIS_MODULE, |
| 187 | }; |
| 188 | |
| 189 | static int __init init(void) |
| 190 | { |
| 191 | int ret; |
| 192 | |
Pablo Neira Ayuso | a45049c | 2006-03-22 13:55:40 -0800 | [diff] [blame] | 193 | ret = xt_register_match(&policy_match); |
Patrick McHardy | c4b8851 | 2006-03-20 18:03:40 -0800 | [diff] [blame] | 194 | if (ret) |
| 195 | return ret; |
Pablo Neira Ayuso | a45049c | 2006-03-22 13:55:40 -0800 | [diff] [blame] | 196 | ret = xt_register_match(&policy6_match); |
Patrick McHardy | c4b8851 | 2006-03-20 18:03:40 -0800 | [diff] [blame] | 197 | if (ret) |
Pablo Neira Ayuso | a45049c | 2006-03-22 13:55:40 -0800 | [diff] [blame] | 198 | xt_unregister_match(&policy_match); |
Patrick McHardy | c4b8851 | 2006-03-20 18:03:40 -0800 | [diff] [blame] | 199 | return ret; |
| 200 | } |
| 201 | |
| 202 | static void __exit fini(void) |
| 203 | { |
Pablo Neira Ayuso | a45049c | 2006-03-22 13:55:40 -0800 | [diff] [blame] | 204 | xt_unregister_match(&policy6_match); |
| 205 | xt_unregister_match(&policy_match); |
Patrick McHardy | c4b8851 | 2006-03-20 18:03:40 -0800 | [diff] [blame] | 206 | } |
| 207 | |
| 208 | module_init(init); |
| 209 | module_exit(fini); |
| 210 | MODULE_ALIAS("ipt_policy"); |
| 211 | MODULE_ALIAS("ip6t_policy"); |