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 connlabel_match(const struct nf_conn *ct, u16 bit)
  22 {
  23         struct nf_conn_labels *labels = nf_ct_labels_find(ct);
  24
  25         if (!labels)
  26                 return false;
  27
  28         return test_bit(bit, labels->bits);
  29 }
  30
  31 static bool
  32 connlabel_mt(const struct sk_buff *skb, struct xt_action_param *par)
  33 {
  34         const struct xt_connlabel_mtinfo *info = par->matchinfo;
  35         enum ip_conntrack_info ctinfo;
  36         struct nf_conn *ct;
  37         bool invert = info->options & XT_CONNLABEL_OP_INVERT;
  38
  39         ct = nf_ct_get(skb, &ctinfo);
  40         if (ct == NULL || nf_ct_is_untracked(ct))
  41                 return invert;
  42
  43         if (info->options & XT_CONNLABEL_OP_SET)
  44                 return (nf_connlabel_set(ct, info->bit) == 0) ^ invert;
  45
  46         return connlabel_match(ct, info->bit) ^ invert;
  47 }
  48
  49 static int connlabel_mt_check(const struct xt_mtchk_param *par)
  50 {
  51         const int options = XT_CONNLABEL_OP_INVERT |
  52                             XT_CONNLABEL_OP_SET;
  53         struct xt_connlabel_mtinfo *info = par->matchinfo;
  54         int ret;
  55
  56         if (info->options & ~options) {
  57                 pr_err("Unknown options in mask %x\n", info->options);
  58                 return -EINVAL;
  59         }
  60
  61         ret = nf_ct_l3proto_try_module_get(par->family);
  62         if (ret < 0) {
  63                 pr_info("cannot load conntrack support for proto=%u\n",
  64                                                         par->family);
  65                 return ret;
  66         }
  67
  68         ret = nf_connlabels_get(par->net, info->bit);
  69         if (ret < 0)
  70                 nf_ct_l3proto_module_put(par->family);
  71         return ret;
  72 }
  73
  74 static void connlabel_mt_destroy(const struct xt_mtdtor_param *par)
  75 {
  76         nf_connlabels_put(par->net);
  77         nf_ct_l3proto_module_put(par->family);
  78 }
  79
  80 static struct xt_match connlabels_mt_reg __read_mostly = {
  81         .name           = "connlabel",
  82         .family         = NFPROTO_UNSPEC,
  83         .checkentry     = connlabel_mt_check,
  84         .match          = connlabel_mt,
  85         .matchsize      = sizeof(struct xt_connlabel_mtinfo),
  86         .destroy        = connlabel_mt_destroy,
  87         .me             = THIS_MODULE,
  88 };
  89
  90 static int __init connlabel_mt_init(void)
  91 {
  92         return xt_register_match(&connlabels_mt_reg);
  93 }
  94
  95 static void __exit connlabel_mt_exit(void)
  96 {
  97         xt_unregister_match(&connlabels_mt_reg);
  98 }
  99
 100 module_init(connlabel_mt_init);
 101 module_exit(connlabel_mt_exit);