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

  /*
   * This module is used to copy security markings from packets
   * to connections, and restore security markings from connections
   * back to packets.  This would normally be performed in conjunction
   * with the SECMARK target and state match.
   *
   * Based somewhat on CONNMARK:

   *   Copyright (C) 2002,2004 MARA Systems AB <https://www.marasystems.com>

   *    by Henrik Nordstrom <hno@marasystems.com>
   *

   * (C) 2006,2008 Red Hat, Inc., James Morris <jmorris@redhat.com>

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>
  #include <linux/skbuff.h>
  #include <linux/netfilter/x_tables.h>
  #include <linux/netfilter/xt_CONNSECMARK.h>

  #include <net/netfilter/nf_conntrack.h>

  #include <net/netfilter/nf_conntrack_ecache.h>

  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("James Morris <jmorris@redhat.com>");

  MODULE_DESCRIPTION("Xtables: target for copying between connection and security mark");

  MODULE_ALIAS("ipt_CONNSECMARK");
  MODULE_ALIAS("ip6t_CONNSECMARK");
  
  /*
   * If the packet has a security mark and the connection does not, copy
   * the security mark from the packet to the connection.
   */

  static void secmark_save(const struct sk_buff *skb)

  {
  	if (skb->secmark) {

  		struct nf_conn *ct;

  		enum ip_conntrack_info ctinfo;

  		ct = nf_ct_get(skb, &ctinfo);

  		if (ct && !ct->secmark) {

  			ct->secmark = skb->secmark;

  			nf_conntrack_event_cache(IPCT_SECMARK, ct);

  		}

  	}
  }
  
  /*
   * If packet has no security mark, and the connection does, restore the
   * security mark from the connection to the packet.
   */
  static void secmark_restore(struct sk_buff *skb)
  {
  	if (!skb->secmark) {

  		const struct nf_conn *ct;

  		enum ip_conntrack_info ctinfo;

  		ct = nf_ct_get(skb, &ctinfo);
  		if (ct && ct->secmark)
  			skb->secmark = ct->secmark;

  	}
  }

  static unsigned int

  connsecmark_tg(struct sk_buff *skb, const struct xt_action_param *par)

  {

  	const struct xt_connsecmark_target_info *info = par->targinfo;

  
  	switch (info->mode) {
  	case CONNSECMARK_SAVE:
  		secmark_save(skb);
  		break;
  
  	case CONNSECMARK_RESTORE:
  		secmark_restore(skb);
  		break;
  
  	default:
  		BUG();
  	}
  
  	return XT_CONTINUE;
  }

  static int connsecmark_tg_check(const struct xt_tgchk_param *par)

  {

  	const struct xt_connsecmark_target_info *info = par->targinfo;

  	int ret;

  	if (strcmp(par->table, "mangle") != 0 &&
  	    strcmp(par->table, "security") != 0) {

  		pr_info_ratelimited("only valid in \'mangle\' or \'security\' table, not \'%s\'
  ",
  				    par->table);

  		return -EINVAL;

  	}

  	switch (info->mode) {
  	case CONNSECMARK_SAVE:
  	case CONNSECMARK_RESTORE:
  		break;
  
  	default:

  		pr_info_ratelimited("invalid mode: %hu
  ", info->mode);

  		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;

  }

  static void connsecmark_tg_destroy(const struct xt_tgdtor_param *par)

  {

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

  }

  static struct xt_target connsecmark_tg_reg __read_mostly = {
  	.name       = "CONNSECMARK",
  	.revision   = 0,
  	.family     = NFPROTO_UNSPEC,
  	.checkentry = connsecmark_tg_check,
  	.destroy    = connsecmark_tg_destroy,
  	.target     = connsecmark_tg,
  	.targetsize = sizeof(struct xt_connsecmark_target_info),
  	.me         = THIS_MODULE,

  };

  static int __init connsecmark_tg_init(void)

  {

  	return xt_register_target(&connsecmark_tg_reg);

  }

  static void __exit connsecmark_tg_exit(void)

  {

  	xt_unregister_target(&connsecmark_tg_reg);

  }

  module_init(connsecmark_tg_init);
  module_exit(connsecmark_tg_exit);