diff options
Diffstat (limited to 'net/netfilter/xt_policy.c')
| -rw-r--r-- | net/netfilter/xt_policy.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/net/netfilter/xt_policy.c b/net/netfilter/xt_policy.c new file mode 100644 index 0000000..328bd20 --- /dev/null +++ b/net/netfilter/xt_policy.c @@ -0,0 +1,191 @@ +/* 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. + */ + +#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; + int strict = info->flags & XT_POLICY_MATCH_STRICT; + int i, pos; + + if (dst->xfrm == NULL) + return -1; + + for (i = 0; dst && dst->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, const struct xt_match_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, par->match->family); + else + ret = match_policy_out(skb, info, par->match->family); + + 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 bool policy_mt_check(const struct xt_mtchk_param *par) +{ + const struct xt_policy_info *info = par->matchinfo; + + if (!(info->flags & (XT_POLICY_MATCH_IN|XT_POLICY_MATCH_OUT))) { + printk(KERN_ERR "xt_policy: neither incoming nor " + "outgoing policy selected\n"); + return false; + } + if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) | + (1 << NF_INET_LOCAL_IN)) && info->flags & XT_POLICY_MATCH_OUT) { + printk(KERN_ERR "xt_policy: output policy not valid in " + "PRE_ROUTING and INPUT\n"); + return false; + } + if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) | + (1 << NF_INET_LOCAL_OUT)) && info->flags & XT_POLICY_MATCH_IN) { + printk(KERN_ERR "xt_policy: input policy not valid in " + "POST_ROUTING and OUTPUT\n"); + return false; + } + if (info->len > XT_POLICY_MAX_ELEM) { + printk(KERN_ERR "xt_policy: too many policy elements\n"); + return false; + } + return true; +} + +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"); |
