linux/net/netfilter/xt_connlabel.c
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   1/*
   2 * (C) 2013 Astaro GmbH & Co KG
   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
   9#include <linux/module.h>
  10#include <linux/skbuff.h>
  11#include <net/netfilter/nf_conntrack.h>
  12#include <net/netfilter/nf_conntrack_labels.h>
  13#include <linux/netfilter/x_tables.h>
  14
  15MODULE_LICENSE("GPL");
  16MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
  17MODULE_DESCRIPTION("Xtables: add/match connection trackling labels");
  18MODULE_ALIAS("ipt_connlabel");
  19MODULE_ALIAS("ip6t_connlabel");
  20
  21static bool
  22connlabel_mt(const struct sk_buff *skb, struct xt_action_param *par)
  23{
  24        const struct xt_connlabel_mtinfo *info = par->matchinfo;
  25        enum ip_conntrack_info ctinfo;
  26        struct nf_conn *ct;
  27        bool invert = info->options & XT_CONNLABEL_OP_INVERT;
  28
  29        ct = nf_ct_get(skb, &ctinfo);
  30        if (ct == NULL || nf_ct_is_untracked(ct))
  31                return invert;
  32
  33        if (info->options & XT_CONNLABEL_OP_SET)
  34                return (nf_connlabel_set(ct, info->bit) == 0) ^ invert;
  35
  36        return nf_connlabel_match(ct, info->bit) ^ invert;
  37}
  38
  39static int connlabel_mt_check(const struct xt_mtchk_param *par)
  40{
  41        const int options = XT_CONNLABEL_OP_INVERT |
  42                            XT_CONNLABEL_OP_SET;
  43        struct xt_connlabel_mtinfo *info = par->matchinfo;
  44        int ret;
  45        size_t words;
  46
  47        if (info->bit > XT_CONNLABEL_MAXBIT)
  48                return -ERANGE;
  49
  50        if (info->options & ~options) {
  51                pr_err("Unknown options in mask %x\n", info->options);
  52                return -EINVAL;
  53        }
  54
  55        ret = nf_ct_l3proto_try_module_get(par->family);
  56        if (ret < 0) {
  57                pr_info("cannot load conntrack support for proto=%u\n",
  58                                                        par->family);
  59                return ret;
  60        }
  61
  62        par->net->ct.labels_used++;
  63        words = BITS_TO_LONGS(info->bit+1);
  64        if (words > par->net->ct.label_words)
  65                par->net->ct.label_words = words;
  66
  67        return ret;
  68}
  69
  70static void connlabel_mt_destroy(const struct xt_mtdtor_param *par)
  71{
  72        par->net->ct.labels_used--;
  73        if (par->net->ct.labels_used == 0)
  74                par->net->ct.label_words = 0;
  75        nf_ct_l3proto_module_put(par->family);
  76}
  77
  78static struct xt_match connlabels_mt_reg __read_mostly = {
  79        .name           = "connlabel",
  80        .family         = NFPROTO_UNSPEC,
  81        .checkentry     = connlabel_mt_check,
  82        .match          = connlabel_mt,
  83        .matchsize      = sizeof(struct xt_connlabel_mtinfo),
  84        .destroy        = connlabel_mt_destroy,
  85        .me             = THIS_MODULE,
  86};
  87
  88static int __init connlabel_mt_init(void)
  89{
  90        return xt_register_match(&connlabels_mt_reg);
  91}
  92
  93static void __exit connlabel_mt_exit(void)
  94{
  95        xt_unregister_match(&connlabels_mt_reg);
  96}
  97
  98module_init(connlabel_mt_init);
  99module_exit(connlabel_mt_exit);
 100
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