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

  /*

   *
   * Generic part shared by ipv4 and ipv6 backends.
   */
  
  #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>
  #include <net/netfilter/nft_fib.h>
  
  const struct nla_policy nft_fib_policy[NFTA_FIB_MAX + 1] = {
  	[NFTA_FIB_DREG]		= { .type = NLA_U32 },
  	[NFTA_FIB_RESULT]	= { .type = NLA_U32 },
  	[NFTA_FIB_FLAGS]	= { .type = NLA_U32 },
  };
  EXPORT_SYMBOL(nft_fib_policy);
  
  #define NFTA_FIB_F_ALL (NFTA_FIB_F_SADDR | NFTA_FIB_F_DADDR | \

  			NFTA_FIB_F_MARK | NFTA_FIB_F_IIF | NFTA_FIB_F_OIF | \
  			NFTA_FIB_F_PRESENT)

  
  int nft_fib_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
  		     const struct nft_data **data)
  {
  	const struct nft_fib *priv = nft_expr_priv(expr);
  	unsigned int hooks;
  
  	switch (priv->result) {

  	case NFT_FIB_RESULT_OIF:

  	case NFT_FIB_RESULT_OIFNAME:
  		hooks = (1 << NF_INET_PRE_ROUTING);
  		break;
  	case NFT_FIB_RESULT_ADDRTYPE:
  		if (priv->flags & NFTA_FIB_F_IIF)
  			hooks = (1 << NF_INET_PRE_ROUTING) |
  				(1 << NF_INET_LOCAL_IN) |
  				(1 << NF_INET_FORWARD);
  		else if (priv->flags & NFTA_FIB_F_OIF)
  			hooks = (1 << NF_INET_LOCAL_OUT) |
  				(1 << NF_INET_POST_ROUTING) |
  				(1 << NF_INET_FORWARD);
  		else
  			hooks = (1 << NF_INET_LOCAL_IN) |
  				(1 << NF_INET_LOCAL_OUT) |
  				(1 << NF_INET_FORWARD) |
  				(1 << NF_INET_PRE_ROUTING) |
  				(1 << NF_INET_POST_ROUTING);
  
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	return nft_chain_validate_hooks(ctx->chain, hooks);
  }
  EXPORT_SYMBOL_GPL(nft_fib_validate);
  
  int nft_fib_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
  		 const struct nlattr * const tb[])
  {
  	struct nft_fib *priv = nft_expr_priv(expr);
  	unsigned int len;
  	int err;
  
  	if (!tb[NFTA_FIB_DREG] || !tb[NFTA_FIB_RESULT] || !tb[NFTA_FIB_FLAGS])
  		return -EINVAL;
  
  	priv->flags = ntohl(nla_get_be32(tb[NFTA_FIB_FLAGS]));
  
  	if (priv->flags == 0 || (priv->flags & ~NFTA_FIB_F_ALL))
  		return -EINVAL;
  
  	if ((priv->flags & (NFTA_FIB_F_SADDR | NFTA_FIB_F_DADDR)) ==
  			   (NFTA_FIB_F_SADDR | NFTA_FIB_F_DADDR))
  		return -EINVAL;
  	if ((priv->flags & (NFTA_FIB_F_IIF | NFTA_FIB_F_OIF)) ==
  			   (NFTA_FIB_F_IIF | NFTA_FIB_F_OIF))
  		return -EINVAL;
  	if ((priv->flags & (NFTA_FIB_F_SADDR | NFTA_FIB_F_DADDR)) == 0)
  		return -EINVAL;

  	priv->result = ntohl(nla_get_be32(tb[NFTA_FIB_RESULT]));

  	priv->dreg = nft_parse_register(tb[NFTA_FIB_DREG]);
  
  	switch (priv->result) {
  	case NFT_FIB_RESULT_OIF:
  		if (priv->flags & NFTA_FIB_F_OIF)
  			return -EINVAL;
  		len = sizeof(int);
  		break;
  	case NFT_FIB_RESULT_OIFNAME:
  		if (priv->flags & NFTA_FIB_F_OIF)
  			return -EINVAL;
  		len = IFNAMSIZ;
  		break;
  	case NFT_FIB_RESULT_ADDRTYPE:
  		len = sizeof(u32);
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	err = nft_validate_register_store(ctx, priv->dreg, NULL,
  					  NFT_DATA_VALUE, len);
  	if (err < 0)
  		return err;

  	return 0;

  }
  EXPORT_SYMBOL_GPL(nft_fib_init);
  
  int nft_fib_dump(struct sk_buff *skb, const struct nft_expr *expr)
  {
  	const struct nft_fib *priv = nft_expr_priv(expr);
  
  	if (nft_dump_register(skb, NFTA_FIB_DREG, priv->dreg))
  		return -1;
  
  	if (nla_put_be32(skb, NFTA_FIB_RESULT, htonl(priv->result)))
  		return -1;
  
  	if (nla_put_be32(skb, NFTA_FIB_FLAGS, htonl(priv->flags)))
  		return -1;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(nft_fib_dump);

  void nft_fib_store_result(void *reg, const struct nft_fib *priv,

  			  const struct net_device *dev)

  {

  	u32 *dreg = reg;

  	int index;

  	switch (priv->result) {

  	case NFT_FIB_RESULT_OIF:

  		index = dev ? dev->ifindex : 0;

  		*dreg = (priv->flags & NFTA_FIB_F_PRESENT) ? !!index : index;

  		break;
  	case NFT_FIB_RESULT_OIFNAME:

  		if (priv->flags & NFTA_FIB_F_PRESENT)
  			*dreg = !!dev;
  		else
  			strncpy(reg, dev ? dev->name : "", IFNAMSIZ);

  		break;
  	default:
  		WARN_ON_ONCE(1);
  		*dreg = 0;
  		break;
  	}
  }
  EXPORT_SYMBOL_GPL(nft_fib_store_result);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");