kernel/net/netfilter/xt_connlabel.c

   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
  15 MODULE_LICENSE("GPL");
  16 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
  17 MODULE_DESCRIPTION("Xtables: add/match connection trackling labels");
  18 MODULE_ALIAS("ipt_connlabel");
  19 MODULE_ALIAS("ip6t_connlabel");
  20
  21 static bool
  22 connlabel_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
  39 static 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
  70 static 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
  78 static 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
  88 static int __init connlabel_mt_init(void)
  89 {
  90         return xt_register_match(&connlabels_mt_reg);
  91 }
  92
  93 static void __exit connlabel_mt_exit(void)
  94 {
  95         xt_unregister_match(&connlabels_mt_reg);
  96 }
  97
  98 module_init(connlabel_mt_init);
  99 module_exit(connlabel_mt_exit);