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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 | // SPDX-License-Identifier: GPL-2.0-only /* IP tables module for matching IPsec policy * * Copyright (c) 2004,2005 Patrick McHardy, <kaber@trash.net> */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/kernel.h> #include <linux/module.h> #include <linux/skbuff.h> #include <linux/init.h> #include <net/xfrm.h> #include <linux/netfilter.h> #include <linux/netfilter/xt_policy.h> #include <linux/netfilter/x_tables.h> MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); MODULE_DESCRIPTION("Xtables: IPsec policy match"); MODULE_LICENSE("GPL"); static inline bool xt_addr_cmp(const union nf_inet_addr *a1, const union nf_inet_addr *m, const union nf_inet_addr *a2, unsigned short family) { switch (family) { case NFPROTO_IPV4: return ((a1->ip ^ a2->ip) & m->ip) == 0; case NFPROTO_IPV6: return ipv6_masked_addr_cmp(&a1->in6, &m->in6, &a2->in6) == 0; } return false; } static bool match_xfrm_state(const struct xfrm_state *x, const struct xt_policy_elem *e, unsigned short family) { #define MATCH_ADDR(x,y,z) (!e->match.x || \ (xt_addr_cmp(&e->x, &e->y, (const union nf_inet_addr *)(z), family) \ ^ e->invert.x)) #define MATCH(x,y) (!e->match.x || ((e->x == (y)) ^ e->invert.x)) return MATCH_ADDR(saddr, smask, &x->props.saddr) && MATCH_ADDR(daddr, dmask, &x->id.daddr) && MATCH(proto, x->id.proto) && MATCH(mode, x->props.mode) && MATCH(spi, x->id.spi) && MATCH(reqid, x->props.reqid); } static int match_policy_in(const struct sk_buff *skb, const struct xt_policy_info *info, unsigned short family) { const struct xt_policy_elem *e; const struct sec_path *sp = skb_sec_path(skb); int strict = info->flags & XT_POLICY_MATCH_STRICT; int i, pos; if (sp == NULL) return -1; if (strict && info->len != sp->len) return 0; for (i = sp->len - 1; i >= 0; i--) { pos = strict ? i - sp->len + 1 : 0; if (pos >= info->len) return 0; e = &info->pol[pos]; if (match_xfrm_state(sp->xvec[i], e, family)) { if (!strict) return 1; } else if (strict) return 0; } return strict ? 1 : 0; } static int match_policy_out(const struct sk_buff *skb, const struct xt_policy_info *info, unsigned short family) { const struct xt_policy_elem *e; const struct dst_entry *dst = skb_dst(skb); int strict = info->flags & XT_POLICY_MATCH_STRICT; int i, pos; if (dst->xfrm == NULL) return -1; for (i = 0; dst && dst->xfrm; dst = ((struct xfrm_dst *)dst)->child, i++) { pos = strict ? i : 0; if (pos >= info->len) return 0; e = &info->pol[pos]; if (match_xfrm_state(dst->xfrm, e, family)) { if (!strict) return 1; } else if (strict) return 0; } return strict ? i == info->len : 0; } static bool policy_mt(const struct sk_buff *skb, struct xt_action_param *par) { const struct xt_policy_info *info = par->matchinfo; int ret; if (info->flags & XT_POLICY_MATCH_IN) ret = match_policy_in(skb, info, xt_family(par)); else ret = match_policy_out(skb, info, xt_family(par)); if (ret < 0) ret = info->flags & XT_POLICY_MATCH_NONE ? true : false; else if (info->flags & XT_POLICY_MATCH_NONE) ret = false; return ret; } static int policy_mt_check(const struct xt_mtchk_param *par) { const struct xt_policy_info *info = par->matchinfo; const char *errmsg = "neither incoming nor outgoing policy selected"; if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT))) goto err; if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_IN)) && info->flags & XT_POLICY_MATCH_OUT) { errmsg = "output policy not valid in PREROUTING and INPUT"; goto err; } if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) | (1 << NF_INET_LOCAL_OUT)) && info->flags & XT_POLICY_MATCH_IN) { errmsg = "input policy not valid in POSTROUTING and OUTPUT"; goto err; } if (info->len > XT_POLICY_MAX_ELEM) { errmsg = "too many policy elements"; goto err; } return 0; err: pr_info_ratelimited("%s\n", errmsg); return -EINVAL; } static struct xt_match policy_mt_reg[] __read_mostly = { { .name = "policy", .family = NFPROTO_IPV4, .checkentry = policy_mt_check, .match = policy_mt, .matchsize = sizeof(struct xt_policy_info), .me = THIS_MODULE, }, { .name = "policy", .family = NFPROTO_IPV6, .checkentry = policy_mt_check, .match = policy_mt, .matchsize = sizeof(struct xt_policy_info), .me = THIS_MODULE, }, }; static int __init policy_mt_init(void) { return xt_register_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg)); } static void __exit policy_mt_exit(void) { xt_unregister_matches(policy_mt_reg, ARRAY_SIZE(policy_mt_reg)); } module_init(policy_mt_init); module_exit(policy_mt_exit); MODULE_ALIAS("ipt_policy"); MODULE_ALIAS("ip6t_policy"); |