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

  /*

   * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>

   *

   * Development of this code funded by Astaro AG (http://www.astaro.com/)
   */

  #include <asm/unaligned.h>

  #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_core.h>
  #include <net/netfilter/nf_tables.h>
  
  struct nft_byteorder {
  	enum nft_registers	sreg:8;
  	enum nft_registers	dreg:8;
  	enum nft_byteorder_ops	op:8;
  	u8			len;
  	u8			size;
  };

  void nft_byteorder_eval(const struct nft_expr *expr,
  			struct nft_regs *regs,
  			const struct nft_pktinfo *pkt)

  {
  	const struct nft_byteorder *priv = nft_expr_priv(expr);

  	u32 *src = &regs->data[priv->sreg];
  	u32 *dst = &regs->data[priv->dreg];

  	union { u32 u32; u16 u16; } *s, *d;
  	unsigned int i;

  	s = (void *)src;
  	d = (void *)dst;

  
  	switch (priv->size) {

  	case 8: {
  		u64 src64;
  
  		switch (priv->op) {
  		case NFT_BYTEORDER_NTOH:
  			for (i = 0; i < priv->len / 8; i++) {

  				src64 = nft_reg_load64(&src[i]);
  				nft_reg_store64(&dst[i], be64_to_cpu(src64));

  			}
  			break;
  		case NFT_BYTEORDER_HTON:
  			for (i = 0; i < priv->len / 8; i++) {

  				src64 = (__force __u64)
  					cpu_to_be64(nft_reg_load64(&src[i]));
  				nft_reg_store64(&dst[i], src64);

  			}
  			break;
  		}
  		break;
  	}

  	case 4:
  		switch (priv->op) {
  		case NFT_BYTEORDER_NTOH:
  			for (i = 0; i < priv->len / 4; i++)
  				d[i].u32 = ntohl((__force __be32)s[i].u32);
  			break;
  		case NFT_BYTEORDER_HTON:
  			for (i = 0; i < priv->len / 4; i++)
  				d[i].u32 = (__force __u32)htonl(s[i].u32);
  			break;
  		}
  		break;
  	case 2:
  		switch (priv->op) {
  		case NFT_BYTEORDER_NTOH:
  			for (i = 0; i < priv->len / 2; i++)
  				d[i].u16 = ntohs((__force __be16)s[i].u16);
  			break;
  		case NFT_BYTEORDER_HTON:
  			for (i = 0; i < priv->len / 2; i++)
  				d[i].u16 = (__force __u16)htons(s[i].u16);
  			break;
  		}
  		break;
  	}
  }
  
  static const struct nla_policy nft_byteorder_policy[NFTA_BYTEORDER_MAX + 1] = {
  	[NFTA_BYTEORDER_SREG]	= { .type = NLA_U32 },
  	[NFTA_BYTEORDER_DREG]	= { .type = NLA_U32 },
  	[NFTA_BYTEORDER_OP]	= { .type = NLA_U32 },
  	[NFTA_BYTEORDER_LEN]	= { .type = NLA_U32 },
  	[NFTA_BYTEORDER_SIZE]	= { .type = NLA_U32 },
  };
  
  static int nft_byteorder_init(const struct nft_ctx *ctx,
  			      const struct nft_expr *expr,
  			      const struct nlattr * const tb[])
  {
  	struct nft_byteorder *priv = nft_expr_priv(expr);

  	u32 size, len;

  	int err;
  
  	if (tb[NFTA_BYTEORDER_SREG] == NULL ||
  	    tb[NFTA_BYTEORDER_DREG] == NULL ||
  	    tb[NFTA_BYTEORDER_LEN] == NULL ||
  	    tb[NFTA_BYTEORDER_SIZE] == NULL ||
  	    tb[NFTA_BYTEORDER_OP] == NULL)
  		return -EINVAL;

  	priv->op = ntohl(nla_get_be32(tb[NFTA_BYTEORDER_OP]));
  	switch (priv->op) {
  	case NFT_BYTEORDER_NTOH:
  	case NFT_BYTEORDER_HTON:
  		break;
  	default:
  		return -EINVAL;
  	}

  	err = nft_parse_u32_check(tb[NFTA_BYTEORDER_SIZE], U8_MAX, &size);
  	if (err < 0)
  		return err;
  
  	priv->size = size;

  	switch (priv->size) {
  	case 2:
  	case 4:

  	case 8:

  		break;
  	default:
  		return -EINVAL;
  	}

  	priv->sreg = nft_parse_register(tb[NFTA_BYTEORDER_SREG]);

  	err = nft_parse_u32_check(tb[NFTA_BYTEORDER_LEN], U8_MAX, &len);
  	if (err < 0)
  		return err;
  
  	priv->len = len;

  	err = nft_validate_register_load(priv->sreg, priv->len);

  	if (err < 0)
  		return err;

  	priv->dreg = nft_parse_register(tb[NFTA_BYTEORDER_DREG]);

  	return nft_validate_register_store(ctx, priv->dreg, NULL,
  					   NFT_DATA_VALUE, priv->len);

  }
  
  static int nft_byteorder_dump(struct sk_buff *skb, const struct nft_expr *expr)
  {
  	const struct nft_byteorder *priv = nft_expr_priv(expr);

  	if (nft_dump_register(skb, NFTA_BYTEORDER_SREG, priv->sreg))

  		goto nla_put_failure;

  	if (nft_dump_register(skb, NFTA_BYTEORDER_DREG, priv->dreg))

  		goto nla_put_failure;
  	if (nla_put_be32(skb, NFTA_BYTEORDER_OP, htonl(priv->op)))
  		goto nla_put_failure;
  	if (nla_put_be32(skb, NFTA_BYTEORDER_LEN, htonl(priv->len)))
  		goto nla_put_failure;
  	if (nla_put_be32(skb, NFTA_BYTEORDER_SIZE, htonl(priv->size)))
  		goto nla_put_failure;
  	return 0;
  
  nla_put_failure:
  	return -1;
  }

  static const struct nft_expr_ops nft_byteorder_ops = {
  	.type		= &nft_byteorder_type,

  	.size		= NFT_EXPR_SIZE(sizeof(struct nft_byteorder)),

  	.eval		= nft_byteorder_eval,
  	.init		= nft_byteorder_init,
  	.dump		= nft_byteorder_dump,

  };

  struct nft_expr_type nft_byteorder_type __read_mostly = {

  	.name		= "byteorder",
  	.ops		= &nft_byteorder_ops,

  	.policy		= nft_byteorder_policy,
  	.maxattr	= NFTA_BYTEORDER_MAX,

  	.owner		= THIS_MODULE,

  };