// 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 <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/netlink.h>
  #include <linux/netfilter.h>

  #include <linux/if_arp.h>

  #include <linux/netfilter/nf_tables.h>
  #include <net/netfilter/nf_tables_core.h>

  #include <net/netfilter/nf_tables_offload.h>

  #include <net/netfilter/nf_tables.h>
  
  struct nft_cmp_expr {
  	struct nft_data		data;
  	enum nft_registers	sreg:8;
  	u8			len;
  	enum nft_cmp_ops	op:8;
  };

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

  {
  	const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  	int d;

  	d = memcmp(&regs->data[priv->sreg], &priv->data, priv->len);

  	switch (priv->op) {
  	case NFT_CMP_EQ:
  		if (d != 0)
  			goto mismatch;
  		break;
  	case NFT_CMP_NEQ:
  		if (d == 0)
  			goto mismatch;
  		break;
  	case NFT_CMP_LT:
  		if (d == 0)
  			goto mismatch;

  		fallthrough;

  	case NFT_CMP_LTE:
  		if (d > 0)
  			goto mismatch;
  		break;
  	case NFT_CMP_GT:
  		if (d == 0)
  			goto mismatch;

  		fallthrough;

  	case NFT_CMP_GTE:
  		if (d < 0)
  			goto mismatch;
  		break;
  	}
  	return;
  
  mismatch:

  	regs->verdict.code = NFT_BREAK;

  }
  
  static const struct nla_policy nft_cmp_policy[NFTA_CMP_MAX + 1] = {
  	[NFTA_CMP_SREG]		= { .type = NLA_U32 },
  	[NFTA_CMP_OP]		= { .type = NLA_U32 },
  	[NFTA_CMP_DATA]		= { .type = NLA_NESTED },
  };
  
  static int nft_cmp_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
  			const struct nlattr * const tb[])
  {
  	struct nft_cmp_expr *priv = nft_expr_priv(expr);
  	struct nft_data_desc desc;
  	int err;

  	err = nft_data_init(NULL, &priv->data, sizeof(priv->data), &desc,
  			    tb[NFTA_CMP_DATA]);

  	if (err < 0)
  		return err;

  	if (desc.type != NFT_DATA_VALUE) {
  		err = -EINVAL;
  		nft_data_release(&priv->data, desc.type);
  		return err;
  	}

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

  	err = nft_validate_register_load(priv->sreg, desc.len);
  	if (err < 0)
  		return err;
  
  	priv->op  = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));

  	priv->len = desc.len;
  	return 0;
  }
  
  static int nft_cmp_dump(struct sk_buff *skb, const struct nft_expr *expr)
  {
  	const struct nft_cmp_expr *priv = nft_expr_priv(expr);

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

  		goto nla_put_failure;
  	if (nla_put_be32(skb, NFTA_CMP_OP, htonl(priv->op)))
  		goto nla_put_failure;
  
  	if (nft_data_dump(skb, NFTA_CMP_DATA, &priv->data,
  			  NFT_DATA_VALUE, priv->len) < 0)
  		goto nla_put_failure;
  	return 0;
  
  nla_put_failure:
  	return -1;
  }

  static int __nft_cmp_offload(struct nft_offload_ctx *ctx,
  			     struct nft_flow_rule *flow,
  			     const struct nft_cmp_expr *priv)
  {
  	struct nft_offload_reg *reg = &ctx->regs[priv->sreg];
  	u8 *mask = (u8 *)&flow->match.mask;
  	u8 *key = (u8 *)&flow->match.key;

  	if (priv->op != NFT_CMP_EQ || priv->len > reg->len)

  		return -EOPNOTSUPP;

  	memcpy(key + reg->offset, &priv->data, reg->len);
  	memcpy(mask + reg->offset, &reg->mask, reg->len);

  
  	flow->match.dissector.used_keys |= BIT(reg->key);
  	flow->match.dissector.offset[reg->key] = reg->base_offset;

  	if (reg->key == FLOW_DISSECTOR_KEY_META &&
  	    reg->offset == offsetof(struct nft_flow_key, meta.ingress_iftype) &&
  	    nft_reg_load16(priv->data.data) != ARPHRD_ETHER)
  		return -EOPNOTSUPP;

  	nft_offload_update_dependency(ctx, &priv->data, reg->len);

  
  	return 0;
  }
  
  static int nft_cmp_offload(struct nft_offload_ctx *ctx,
  			   struct nft_flow_rule *flow,
  			   const struct nft_expr *expr)
  {
  	const struct nft_cmp_expr *priv = nft_expr_priv(expr);
  
  	return __nft_cmp_offload(ctx, flow, priv);
  }

  static const struct nft_expr_ops nft_cmp_ops = {
  	.type		= &nft_cmp_type,

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

  	.eval		= nft_cmp_eval,
  	.init		= nft_cmp_init,
  	.dump		= nft_cmp_dump,

  	.offload	= nft_cmp_offload,

  };

  static int nft_cmp_fast_init(const struct nft_ctx *ctx,
  			     const struct nft_expr *expr,
  			     const struct nlattr * const tb[])
  {
  	struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  	struct nft_data_desc desc;
  	struct nft_data data;

  	int err;

  	err = nft_data_init(NULL, &data, sizeof(data), &desc,
  			    tb[NFTA_CMP_DATA]);

  	if (err < 0)
  		return err;

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

  	err = nft_validate_register_load(priv->sreg, desc.len);
  	if (err < 0)
  		return err;
  
  	desc.len *= BITS_PER_BYTE;

  	priv->mask = nft_cmp_fast_mask(desc.len);
  	priv->data = data.data[0] & priv->mask;

  	priv->len  = desc.len;

  	priv->inv  = ntohl(nla_get_be32(tb[NFTA_CMP_OP])) != NFT_CMP_EQ;

  	return 0;
  }

  static int nft_cmp_fast_offload(struct nft_offload_ctx *ctx,
  				struct nft_flow_rule *flow,
  				const struct nft_expr *expr)
  {
  	const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  	struct nft_cmp_expr cmp = {
  		.data	= {
  			.data	= {
  				[0] = priv->data,
  			},
  		},
  		.sreg	= priv->sreg,
  		.len	= priv->len / BITS_PER_BYTE,

  		.op	= priv->inv ? NFT_CMP_NEQ : NFT_CMP_EQ,

  	};
  
  	return __nft_cmp_offload(ctx, flow, &cmp);
  }

  static int nft_cmp_fast_dump(struct sk_buff *skb, const struct nft_expr *expr)
  {
  	const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);

  	enum nft_cmp_ops op = priv->inv ? NFT_CMP_NEQ : NFT_CMP_EQ;

  	struct nft_data data;

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

  		goto nla_put_failure;

  	if (nla_put_be32(skb, NFTA_CMP_OP, htonl(op)))

  		goto nla_put_failure;
  
  	data.data[0] = priv->data;
  	if (nft_data_dump(skb, NFTA_CMP_DATA, &data,
  			  NFT_DATA_VALUE, priv->len / BITS_PER_BYTE) < 0)
  		goto nla_put_failure;
  	return 0;
  
  nla_put_failure:
  	return -1;
  }
  
  const struct nft_expr_ops nft_cmp_fast_ops = {
  	.type		= &nft_cmp_type,
  	.size		= NFT_EXPR_SIZE(sizeof(struct nft_cmp_fast_expr)),
  	.eval		= NULL,	/* inlined */
  	.init		= nft_cmp_fast_init,
  	.dump		= nft_cmp_fast_dump,

  	.offload	= nft_cmp_fast_offload,

  };

  static const struct nft_expr_ops *
  nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])

  {
  	struct nft_data_desc desc;
  	struct nft_data data;

  	enum nft_cmp_ops op;
  	int err;
  
  	if (tb[NFTA_CMP_SREG] == NULL ||
  	    tb[NFTA_CMP_OP] == NULL ||
  	    tb[NFTA_CMP_DATA] == NULL)
  		return ERR_PTR(-EINVAL);

  	op = ntohl(nla_get_be32(tb[NFTA_CMP_OP]));
  	switch (op) {
  	case NFT_CMP_EQ:
  	case NFT_CMP_NEQ:
  	case NFT_CMP_LT:
  	case NFT_CMP_LTE:
  	case NFT_CMP_GT:
  	case NFT_CMP_GTE:
  		break;
  	default:
  		return ERR_PTR(-EINVAL);
  	}

  	err = nft_data_init(NULL, &data, sizeof(data), &desc,
  			    tb[NFTA_CMP_DATA]);

  	if (err < 0)
  		return ERR_PTR(err);

  	if (desc.type != NFT_DATA_VALUE) {
  		err = -EINVAL;
  		goto err1;
  	}

  	if (desc.len <= sizeof(u32) && (op == NFT_CMP_EQ || op == NFT_CMP_NEQ))

  		return &nft_cmp_fast_ops;

  
  	return &nft_cmp_ops;
  err1:

  	nft_data_release(&data, desc.type);

  	return ERR_PTR(-EINVAL);

  }

  struct nft_expr_type nft_cmp_type __read_mostly = {

  	.name		= "cmp",

  	.select_ops	= nft_cmp_select_ops,

  	.policy		= nft_cmp_policy,
  	.maxattr	= NFTA_CMP_MAX,

  	.owner		= THIS_MODULE,

  };