/* IP tables module for matching IPsec policy * * Copyright (c) 2004,2005 Patrick McHardy, <kaber@trash.net> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #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->sp; 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");