LXR linux/net/ipv6/netfilter/ip6t

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C)2006 USAGI/WIDE Project
   4 *
   5 * Author:
   6 *      Masahide NAKAMURA @USAGI <masahide.nakamura.cz@hitachi.com>
   7 *
   8 * Based on net/netfilter/xt_tcpudp.c
   9 */
  10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11#include <linux/types.h>
  12#include <linux/module.h>
  13#include <net/ip.h>
  14#include <linux/ipv6.h>
  15#include <net/ipv6.h>
  16#include <net/mip6.h>
  17
  18#include <linux/netfilter/x_tables.h>
  19#include <linux/netfilter_ipv6/ip6t_mh.h>
  20
  21MODULE_DESCRIPTION("Xtables: IPv6 Mobility Header match");
  22MODULE_LICENSE("GPL");
  23
  24/* Returns 1 if the type is matched by the range, 0 otherwise */
  25static inline bool
  26type_match(u_int8_t min, u_int8_t max, u_int8_t type, bool invert)
  27{
  28        return (type >= min && type <= max) ^ invert;
  29}
  30
  31static bool mh_mt6(const struct sk_buff *skb, struct xt_action_param *par)
  32{
  33        struct ip6_mh _mh;
  34        const struct ip6_mh *mh;
  35        const struct ip6t_mh *mhinfo = par->matchinfo;
  36
  37        /* Must not be a fragment. */
  38        if (par->fragoff != 0)
  39                return false;
  40
  41        mh = skb_header_pointer(skb, par->thoff, sizeof(_mh), &_mh);
  42        if (mh == NULL) {
  43                /* We've been asked to examine this packet, and we
  44                   can't.  Hence, no choice but to drop. */
  45                pr_debug("Dropping evil MH tinygram.\n");
  46                par->hotdrop = true;
  47                return false;
  48        }
  49
  50        if (mh->ip6mh_proto != IPPROTO_NONE) {
  51                pr_debug("Dropping invalid MH Payload Proto: %u\n",
  52                         mh->ip6mh_proto);
  53                par->hotdrop = true;
  54                return false;
  55        }
  56
  57        return type_match(mhinfo->types[0], mhinfo->types[1], mh->ip6mh_type,
  58                          !!(mhinfo->invflags & IP6T_MH_INV_TYPE));
  59}
  60
  61static int mh_mt6_check(const struct xt_mtchk_param *par)
  62{
  63        const struct ip6t_mh *mhinfo = par->matchinfo;
  64
  65        /* Must specify no unknown invflags */
  66        return (mhinfo->invflags & ~IP6T_MH_INV_MASK) ? -EINVAL : 0;
  67}
  68
  69static struct xt_match mh_mt6_reg __read_mostly = {
  70        .name           = "mh",
  71        .family         = NFPROTO_IPV6,
  72        .checkentry     = mh_mt6_check,
  73        .match          = mh_mt6,
  74        .matchsize      = sizeof(struct ip6t_mh),
  75        .proto          = IPPROTO_MH,
  76        .me             = THIS_MODULE,
  77};
  78
  79static int __init mh_mt6_init(void)
  80{
  81        return xt_register_match(&mh_mt6_reg);
  82}
  83
  84static void __exit mh_mt6_exit(void)
  85{
  86        xt_unregister_match(&mh_mt6_reg);
  87}
  88
  89module_init(mh_mt6_init);
  90module_exit(mh_mt6_exit);
  91