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

  /*
   * Copyright (c) 2014 Patrick McHardy <kaber@trash.net>

   */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/netlink.h>
  #include <linux/netfilter.h>
  #include <linux/netfilter/nf_tables.h>
  #include <net/netfilter/nf_tables.h>
  #include <net/netfilter/nft_reject.h>

  #include <net/netfilter/ipv4/nf_reject.h>
  #include <net/netfilter/ipv6/nf_reject.h>

  
  static void nft_reject_inet_eval(const struct nft_expr *expr,

  				 struct nft_regs *regs,

  				 const struct nft_pktinfo *pkt)
  {

  	struct nft_reject *priv = nft_expr_priv(expr);

  	switch (nft_pf(pkt)) {

  	case NFPROTO_IPV4:

  		switch (priv->type) {
  		case NFT_REJECT_ICMP_UNREACH:

  			nf_send_unreach(pkt->skb, priv->icmp_code,

  					nft_hook(pkt));

  			break;
  		case NFT_REJECT_TCP_RST:

  			nf_send_reset(nft_net(pkt), pkt->skb, nft_hook(pkt));

  			break;
  		case NFT_REJECT_ICMPX_UNREACH:
  			nf_send_unreach(pkt->skb,

  					nft_reject_icmp_code(priv->icmp_code),

  					nft_hook(pkt));

  			break;
  		}
  		break;

  	case NFPROTO_IPV6:

  		switch (priv->type) {
  		case NFT_REJECT_ICMP_UNREACH:

  			nf_send_unreach6(nft_net(pkt), pkt->skb,
  					 priv->icmp_code, nft_hook(pkt));

  			break;
  		case NFT_REJECT_TCP_RST:

  			nf_send_reset6(nft_net(pkt), pkt->skb, nft_hook(pkt));

  			break;
  		case NFT_REJECT_ICMPX_UNREACH:

  			nf_send_unreach6(nft_net(pkt), pkt->skb,

  					 nft_reject_icmpv6_code(priv->icmp_code),

  					 nft_hook(pkt));

  			break;
  		}
  		break;
  	}

  
  	regs->verdict.code = NF_DROP;

  }
  
  static int nft_reject_inet_init(const struct nft_ctx *ctx,
  				const struct nft_expr *expr,
  				const struct nlattr * const tb[])
  {
  	struct nft_reject *priv = nft_expr_priv(expr);

  	int icmp_code;

  
  	if (tb[NFTA_REJECT_TYPE] == NULL)
  		return -EINVAL;
  
  	priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
  	switch (priv->type) {
  	case NFT_REJECT_ICMP_UNREACH:
  	case NFT_REJECT_ICMPX_UNREACH:
  		if (tb[NFTA_REJECT_ICMP_CODE] == NULL)
  			return -EINVAL;
  
  		icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]);
  		if (priv->type == NFT_REJECT_ICMPX_UNREACH &&
  		    icmp_code > NFT_REJECT_ICMPX_MAX)
  			return -EINVAL;
  
  		priv->icmp_code = icmp_code;
  		break;
  	case NFT_REJECT_TCP_RST:
  		break;
  	default:
  		return -EINVAL;

  	}

  	return 0;
  }
  
  static int nft_reject_inet_dump(struct sk_buff *skb,
  				const struct nft_expr *expr)
  {
  	const struct nft_reject *priv = nft_expr_priv(expr);
  
  	if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
  		goto nla_put_failure;
  
  	switch (priv->type) {
  	case NFT_REJECT_ICMP_UNREACH:
  	case NFT_REJECT_ICMPX_UNREACH:
  		if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code))
  			goto nla_put_failure;
  		break;

  	default:
  		break;

  	}
  
  	return 0;
  
  nla_put_failure:
  	return -1;

  }
  
  static struct nft_expr_type nft_reject_inet_type;
  static const struct nft_expr_ops nft_reject_inet_ops = {
  	.type		= &nft_reject_inet_type,
  	.size		= NFT_EXPR_SIZE(sizeof(struct nft_reject)),
  	.eval		= nft_reject_inet_eval,

  	.init		= nft_reject_inet_init,
  	.dump		= nft_reject_inet_dump,

  	.validate	= nft_reject_validate,

  };
  
  static struct nft_expr_type nft_reject_inet_type __read_mostly = {
  	.family		= NFPROTO_INET,
  	.name		= "reject",
  	.ops		= &nft_reject_inet_ops,
  	.policy		= nft_reject_policy,
  	.maxattr	= NFTA_REJECT_MAX,
  	.owner		= THIS_MODULE,
  };
  
  static int __init nft_reject_inet_module_init(void)
  {
  	return nft_register_expr(&nft_reject_inet_type);
  }
  
  static void __exit nft_reject_inet_module_exit(void)
  {
  	nft_unregister_expr(&nft_reject_inet_type);
  }
  
  module_init(nft_reject_inet_module_init);
  module_exit(nft_reject_inet_module_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  MODULE_ALIAS_NFT_AF_EXPR(1, "reject");