net/netfilter/xt_connlabel.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * (C) 2013 Astaro GmbH & Co KG
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/skbuff.h>
   8 #include <net/netfilter/nf_conntrack.h>
   9 #include <net/netfilter/nf_conntrack_ecache.h>
  10 #include <net/netfilter/nf_conntrack_labels.h>
  11 #include <linux/netfilter/x_tables.h>
  12
  13 MODULE_LICENSE("GPL");
  14 MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
  15 MODULE_DESCRIPTION("Xtables: add/match connection tracking labels");
  16 MODULE_ALIAS("ipt_connlabel");
  17 MODULE_ALIAS("ip6t_connlabel");
  18
  19 static bool
  20 connlabel_mt(const struct sk_buff *skb, struct xt_action_param *par)
  21 {
  22         const struct xt_connlabel_mtinfo *info = par->matchinfo;
  23         enum ip_conntrack_info ctinfo;
  24         struct nf_conn_labels *labels;
  25         struct nf_conn *ct;
  26         bool invert = info->options & XT_CONNLABEL_OP_INVERT;
  27
  28         ct = nf_ct_get(skb, &ctinfo);
  29         if (ct == NULL)
  30                 return invert;
  31
  32         labels = nf_ct_labels_find(ct);
  33         if (!labels)
  34                 return invert;
  35
  36         if (test_bit(info->bit, labels->bits))
  37                 return !invert;
  38
  39         if (info->options & XT_CONNLABEL_OP_SET) {
  40                 if (!test_and_set_bit(info->bit, labels->bits))
  41                         nf_conntrack_event_cache(IPCT_LABEL, ct);
  42
  43                 return !invert;
  44         }
  45
  46         return 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_info_ratelimited("Unknown options in mask %x\n",
  58                                     info->options);
  59                 return -EINVAL;
  60         }
  61
  62         ret = nf_ct_netns_get(par->net, par->family);
  63         if (ret < 0) {
  64                 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
  65                                     par->family);
  66                 return ret;
  67         }
  68
  69         ret = nf_connlabels_get(par->net, info->bit);
  70         if (ret < 0)
  71                 nf_ct_netns_put(par->net, par->family);
  72         return ret;
  73 }
  74
  75 static void connlabel_mt_destroy(const struct xt_mtdtor_param *par)
  76 {
  77         nf_connlabels_put(par->net);
  78         nf_ct_netns_put(par->net, par->family);
  79 }
  80
  81 static struct xt_match connlabels_mt_reg __read_mostly = {
  82         .name           = "connlabel",
  83         .family         = NFPROTO_UNSPEC,
  84         .checkentry     = connlabel_mt_check,
  85         .match          = connlabel_mt,
  86         .matchsize      = sizeof(struct xt_connlabel_mtinfo),
  87         .destroy        = connlabel_mt_destroy,
  88         .me             = THIS_MODULE,
  89 };
  90
  91 static int __init connlabel_mt_init(void)
  92 {
  93         return xt_register_match(&connlabels_mt_reg);
  94 }
  95
  96 static void __exit connlabel_mt_exit(void)
  97 {
  98         xt_unregister_match(&connlabels_mt_reg);
  99 }
 100
 101 module_init(connlabel_mt_init);
 102 module_exit(connlabel_mt_exit);