LXR linux/net/netfilter/xt

   1// SPDX-License-Identifier: GPL-2.0-only
   2/* Kernel module to match connection tracking information. */
   3
   4/* (C) 1999-2001 Paul `Rusty' Russell
   5 * (C) 2002-2005 Netfilter Core Team <coreteam@netfilter.org>
   6 */
   7
   8#include <linux/module.h>
   9#include <linux/skbuff.h>
  10#include <net/netfilter/nf_conntrack.h>
  11#include <linux/netfilter/x_tables.h>
  12#include <linux/netfilter/xt_state.h>
  13
  14MODULE_LICENSE("GPL");
  15MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
  16MODULE_DESCRIPTION("ip[6]_tables connection tracking state match module");
  17MODULE_ALIAS("ipt_state");
  18MODULE_ALIAS("ip6t_state");
  19
  20static bool
  21state_mt(const struct sk_buff *skb, struct xt_action_param *par)
  22{
  23        const struct xt_state_info *sinfo = par->matchinfo;
  24        enum ip_conntrack_info ctinfo;
  25        unsigned int statebit;
  26        struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  27
  28        if (ct)
  29                statebit = XT_STATE_BIT(ctinfo);
  30        else if (ctinfo == IP_CT_UNTRACKED)
  31                statebit = XT_STATE_UNTRACKED;
  32        else
  33                statebit = XT_STATE_INVALID;
  34
  35        return (sinfo->statemask & statebit);
  36}
  37
  38static int state_mt_check(const struct xt_mtchk_param *par)
  39{
  40        int ret;
  41
  42        ret = nf_ct_netns_get(par->net, par->family);
  43        if (ret < 0)
  44                pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
  45                                    par->family);
  46        return ret;
  47}
  48
  49static void state_mt_destroy(const struct xt_mtdtor_param *par)
  50{
  51        nf_ct_netns_put(par->net, par->family);
  52}
  53
  54static struct xt_match state_mt_reg __read_mostly = {
  55        .name       = "state",
  56        .family     = NFPROTO_UNSPEC,
  57        .checkentry = state_mt_check,
  58        .match      = state_mt,
  59        .destroy    = state_mt_destroy,
  60        .matchsize  = sizeof(struct xt_state_info),
  61        .me         = THIS_MODULE,
  62};
  63
  64static int __init state_mt_init(void)
  65{
  66        return xt_register_match(&state_mt_reg);
  67}
  68
  69static void __exit state_mt_exit(void)
  70{
  71        xt_unregister_match(&state_mt_reg);
  72}
  73
  74module_init(state_mt_init);
  75module_exit(state_mt_exit);
  76