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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15#include <linux/types.h>
  16#include <linux/module.h>
  17#include <net/ip.h>
  18#include <linux/ipv6.h>
  19#include <net/ipv6.h>
  20#include <net/mip6.h>
  21
  22#include <linux/netfilter/x_tables.h>
  23#include <linux/netfilter_ipv6/ip6t_mh.h>
  24
  25MODULE_DESCRIPTION("Xtables: IPv6 Mobility Header match");
  26MODULE_LICENSE("GPL");
  27
  28/* Returns 1 if the type is matched by the range, 0 otherwise */
  29static inline bool
  30type_match(u_int8_t min, u_int8_t max, u_int8_t type, bool invert)
  31{
  32        return (type >= min && type <= max) ^ invert;
  33}
  34
  35static bool mh_mt6(const struct sk_buff *skb, struct xt_action_param *par)
  36{
  37        struct ip6_mh _mh;
  38        const struct ip6_mh *mh;
  39        const struct ip6t_mh *mhinfo = par->matchinfo;
  40
  41        /* Must not be a fragment. */
  42        if (par->fragoff != 0)
  43                return false;
  44
  45        mh = skb_header_pointer(skb, par->thoff, sizeof(_mh), &_mh);
  46        if (mh == NULL) {
  47                /* We've been asked to examine this packet, and we
  48                   can't.  Hence, no choice but to drop. */
  49                pr_debug("Dropping evil MH tinygram.\n");
  50                par->hotdrop = true;
  51                return false;
  52        }
  53
  54        if (mh->ip6mh_proto != IPPROTO_NONE) {
  55                pr_debug("Dropping invalid MH Payload Proto: %u\n",
  56                         mh->ip6mh_proto);
  57                par->hotdrop = true;
  58                return false;
  59        }
  60
  61        return type_match(mhinfo->types[0], mhinfo->types[1], mh->ip6mh_type,
  62                          !!(mhinfo->invflags & IP6T_MH_INV_TYPE));
  63}
  64
  65static int mh_mt6_check(const struct xt_mtchk_param *par)
  66{
  67        const struct ip6t_mh *mhinfo = par->matchinfo;
  68
  69        /* Must specify no unknown invflags */
  70        return (mhinfo->invflags & ~IP6T_MH_INV_MASK) ? -EINVAL : 0;
  71}
  72
  73static struct xt_match mh_mt6_reg __read_mostly = {
  74        .name           = "mh",
  75        .family         = NFPROTO_IPV6,
  76        .checkentry     = mh_mt6_check,
  77        .match          = mh_mt6,
  78        .matchsize      = sizeof(struct ip6t_mh),
  79        .proto          = IPPROTO_MH,
  80        .me             = THIS_MODULE,
  81};
  82
  83static int __init mh_mt6_init(void)
  84{
  85        return xt_register_match(&mh_mt6_reg);
  86}
  87
  88static void __exit mh_mt6_exit(void)
  89{
  90        xt_unregister_match(&mh_mt6_reg);
  91}
  92
  93module_init(mh_mt6_init);
  94module_exit(mh_mt6_exit);
  95