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_ecache.h>
  13 #include <net/netfilter/nf_conntrack_labels.h>
  14 #include <linux/netfilter/x_tables.h>
  15
  16 MODULE_LICENSE("GPL");
  17 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
  18 MODULE_DESCRIPTION("Xtables: add/match connection trackling labels");
  19 MODULE_ALIAS("ipt_connlabel");
  20 MODULE_ALIAS("ip6t_connlabel");
  21
  22 static bool
  23 connlabel_mt(const struct sk_buff *skb, struct xt_action_param *par)
  24 {
  25         const struct xt_connlabel_mtinfo *info = par->matchinfo;
  26         enum ip_conntrack_info ctinfo;
  27         struct nf_conn_labels *labels;
  28         struct nf_conn *ct;
  29         bool invert = info->options & XT_CONNLABEL_OP_INVERT;
  30
  31         ct = nf_ct_get(skb, &ctinfo);
  32         if (ct == NULL || nf_ct_is_untracked(ct))
  33                 return invert;
  34
  35         labels = nf_ct_labels_find(ct);
  36         if (!labels)
  37                 return invert;
  38
  39         if (test_bit(info->bit, labels->bits))
  40                 return !invert;
  41
  42         if (info->options & XT_CONNLABEL_OP_SET) {
  43                 if (!test_and_set_bit(info->bit, labels->bits))
  44                         nf_conntrack_event_cache(IPCT_LABEL, ct);
  45
  46                 return !invert;
  47         }
  48
  49         return invert;
  50 }
  51
  52 static int connlabel_mt_check(const struct xt_mtchk_param *par)
  53 {
  54         const int options = XT_CONNLABEL_OP_INVERT |
  55                             XT_CONNLABEL_OP_SET;
  56         struct xt_connlabel_mtinfo *info = par->matchinfo;
  57         int ret;
  58
  59         if (info->options & ~options) {
  60                 pr_err("Unknown options in mask %x\n", info->options);
  61                 return -EINVAL;
  62         }
  63
  64         ret = nf_ct_l3proto_try_module_get(par->family);
  65         if (ret < 0) {
  66                 pr_info("cannot load conntrack support for proto=%u\n",
  67                                                         par->family);
  68                 return ret;
  69         }
  70
  71         ret = nf_connlabels_get(par->net, info->bit);
  72         if (ret < 0)
  73                 nf_ct_l3proto_module_put(par->family);
  74         return ret;
  75 }
  76
  77 static void connlabel_mt_destroy(const struct xt_mtdtor_param *par)
  78 {
  79         nf_connlabels_put(par->net);
  80         nf_ct_l3proto_module_put(par->family);
  81 }
  82
  83 static struct xt_match connlabels_mt_reg __read_mostly = {
  84         .name           = "connlabel",
  85         .family         = NFPROTO_UNSPEC,
  86         .checkentry     = connlabel_mt_check,
  87         .match          = connlabel_mt,
  88         .matchsize      = sizeof(struct xt_connlabel_mtinfo),
  89         .destroy        = connlabel_mt_destroy,
  90         .me             = THIS_MODULE,
  91 };
  92
  93 static int __init connlabel_mt_init(void)
  94 {
  95         return xt_register_match(&connlabels_mt_reg);
  96 }
  97
  98 static void __exit connlabel_mt_exit(void)
  99 {
 100         xt_unregister_match(&connlabels_mt_reg);
 101 }
 102
 103 module_init(connlabel_mt_init);
 104 module_exit(connlabel_mt_exit);