// SPDX-License-Identifier: GPL-2.0-only

  /*
   * (C) 2013 Astaro GmbH & Co KG

   */
  
  #include <linux/module.h>
  #include <linux/skbuff.h>
  #include <net/netfilter/nf_conntrack.h>

  #include <net/netfilter/nf_conntrack_ecache.h>

  #include <net/netfilter/nf_conntrack_labels.h>
  #include <linux/netfilter/x_tables.h>
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");

  MODULE_DESCRIPTION("Xtables: add/match connection tracking labels");

  MODULE_ALIAS("ipt_connlabel");
  MODULE_ALIAS("ip6t_connlabel");
  
  static bool
  connlabel_mt(const struct sk_buff *skb, struct xt_action_param *par)
  {
  	const struct xt_connlabel_mtinfo *info = par->matchinfo;
  	enum ip_conntrack_info ctinfo;

  	struct nf_conn_labels *labels;

  	struct nf_conn *ct;
  	bool invert = info->options & XT_CONNLABEL_OP_INVERT;
  
  	ct = nf_ct_get(skb, &ctinfo);

  	if (ct == NULL)

  		return invert;

  	labels = nf_ct_labels_find(ct);
  	if (!labels)
  		return invert;
  
  	if (test_bit(info->bit, labels->bits))
  		return !invert;
  
  	if (info->options & XT_CONNLABEL_OP_SET) {
  		if (!test_and_set_bit(info->bit, labels->bits))
  			nf_conntrack_event_cache(IPCT_LABEL, ct);
  
  		return !invert;
  	}

  	return invert;

  }
  
  static int connlabel_mt_check(const struct xt_mtchk_param *par)
  {
  	const int options = XT_CONNLABEL_OP_INVERT |
  			    XT_CONNLABEL_OP_SET;
  	struct xt_connlabel_mtinfo *info = par->matchinfo;
  	int ret;

  
  	if (info->options & ~options) {

  		pr_info_ratelimited("Unknown options in mask %x
  ",
  				    info->options);

  		return -EINVAL;
  	}

  	ret = nf_ct_netns_get(par->net, par->family);

  	if (ret < 0) {

  		pr_info_ratelimited("cannot load conntrack support for proto=%u
  ",
  				    par->family);

  		return ret;
  	}

  	ret = nf_connlabels_get(par->net, info->bit);

  	if (ret < 0)

  		nf_ct_netns_put(par->net, par->family);

  	return ret;
  }
  
  static void connlabel_mt_destroy(const struct xt_mtdtor_param *par)
  {

  	nf_connlabels_put(par->net);

  	nf_ct_netns_put(par->net, par->family);

  }
  
  static struct xt_match connlabels_mt_reg __read_mostly = {
  	.name           = "connlabel",
  	.family         = NFPROTO_UNSPEC,
  	.checkentry     = connlabel_mt_check,
  	.match          = connlabel_mt,
  	.matchsize      = sizeof(struct xt_connlabel_mtinfo),
  	.destroy        = connlabel_mt_destroy,
  	.me             = THIS_MODULE,
  };
  
  static int __init connlabel_mt_init(void)
  {
  	return xt_register_match(&connlabels_mt_reg);
  }
  
  static void __exit connlabel_mt_exit(void)
  {
  	xt_unregister_match(&connlabels_mt_reg);
  }
  
  module_init(connlabel_mt_init);
  module_exit(connlabel_mt_exit);