LXR linux/net/ipv6/netfilter/ip6t

   1/*
   2 * Copyright (C)2006 USAGI/WIDE Project
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * Author:
   9 *      Masahide NAKAMURA @USAGI <masahide.nakamura.cz@hitachi.com>
  10 *
  11 * Based on net/netfilter/xt_tcpudp.c
  12 *
  13 */
  14#include <linux/types.h>
  15#include <linux/module.h>
  16#include <net/ip.h>
  17#include <linux/ipv6.h>
  18#include <net/ipv6.h>
  19#include <net/mip6.h>
  20
  21#include <linux/netfilter/x_tables.h>
  22#include <linux/netfilter_ipv6/ip6t_mh.h>
  23
  24MODULE_DESCRIPTION("Xtables: IPv6 Mobility Header match");
  25MODULE_LICENSE("GPL");
  26
  27#ifdef DEBUG_IP_FIREWALL_USER
  28#define duprintf(format, args...) printk(format , ## args)
  29#else
  30#define duprintf(format, args...)
  31#endif
  32
  33/* Returns 1 if the type is matched by the range, 0 otherwise */
  34static inline bool
  35type_match(u_int8_t min, u_int8_t max, u_int8_t type, bool invert)
  36{
  37        return (type >= min && type <= max) ^ invert;
  38}
  39
  40static bool mh_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
  41{
  42        struct ip6_mh _mh;
  43        const struct ip6_mh *mh;
  44        const struct ip6t_mh *mhinfo = par->matchinfo;
  45
  46        /* Must not be a fragment. */
  47        if (par->fragoff != 0)
  48                return false;
  49
  50        mh = skb_header_pointer(skb, par->thoff, sizeof(_mh), &_mh);
  51        if (mh == NULL) {
  52                /* We've been asked to examine this packet, and we
  53                   can't.  Hence, no choice but to drop. */
  54                duprintf("Dropping evil MH tinygram.\n");
  55                *par->hotdrop = true;
  56                return false;
  57        }
  58
  59        if (mh->ip6mh_proto != IPPROTO_NONE) {
  60                duprintf("Dropping invalid MH Payload Proto: %u\n",
  61                         mh->ip6mh_proto);
  62                *par->hotdrop = true;
  63                return false;
  64        }
  65
  66        return type_match(mhinfo->types[0], mhinfo->types[1], mh->ip6mh_type,
  67                          !!(mhinfo->invflags & IP6T_MH_INV_TYPE));
  68}
  69
  70static bool mh_mt6_check(const struct xt_mtchk_param *par)
  71{
  72        const struct ip6t_mh *mhinfo = par->matchinfo;
  73
  74        /* Must specify no unknown invflags */
  75        return !(mhinfo->invflags & ~IP6T_MH_INV_MASK);
  76}
  77
  78static struct xt_match mh_mt6_reg __read_mostly = {
  79        .name           = "mh",
  80        .family         = NFPROTO_IPV6,
  81        .checkentry     = mh_mt6_check,
  82        .match          = mh_mt6,
  83        .matchsize      = sizeof(struct ip6t_mh),
  84        .proto          = IPPROTO_MH,
  85        .me             = THIS_MODULE,
  86};
  87
  88static int __init mh_mt6_init(void)
  89{
  90        return xt_register_match(&mh_mt6_reg);
  91}
  92
  93static void __exit mh_mt6_exit(void)
  94{
  95        xt_unregister_match(&mh_mt6_reg);
  96}
  97
  98module_init(mh_mt6_init);
  99module_exit(mh_mt6_exit);
 100