/*
   * Copyright (c) 2013 Eric Leblond <eric@regit.org>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * Development of this code partly funded by OISF
   * (http://www.openinfosecfoundation.org/)
   */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/netlink.h>
  #include <linux/jhash.h>
  #include <linux/netfilter.h>
  #include <linux/netfilter/nf_tables.h>
  #include <net/netfilter/nf_tables.h>
  #include <net/netfilter/nf_queue.h>
  
  static u32 jhash_initval __read_mostly;
  
  struct nft_queue {

  	enum nft_registers	sreg_qnum:8;
  	u16			queuenum;
  	u16			queues_total;
  	u16			flags;

  };
  
  static void nft_queue_eval(const struct nft_expr *expr,

  			   struct nft_regs *regs,

  			   const struct nft_pktinfo *pkt)
  {
  	struct nft_queue *priv = nft_expr_priv(expr);
  	u32 queue = priv->queuenum;
  	u32 ret;
  
  	if (priv->queues_total > 1) {
  		if (priv->flags & NFT_QUEUE_FLAG_CPU_FANOUT) {

  			int cpu = raw_smp_processor_id();

  
  			queue = priv->queuenum + cpu % priv->queues_total;
  		} else {
  			queue = nfqueue_hash(pkt->skb, queue,

  					     priv->queues_total, nft_pf(pkt),

  					     jhash_initval);
  		}
  	}
  
  	ret = NF_QUEUE_NR(queue);
  	if (priv->flags & NFT_QUEUE_FLAG_BYPASS)
  		ret |= NF_VERDICT_FLAG_QUEUE_BYPASS;

  	regs->verdict.code = ret;

  }

  static void nft_queue_sreg_eval(const struct nft_expr *expr,
  				struct nft_regs *regs,
  				const struct nft_pktinfo *pkt)
  {
  	struct nft_queue *priv = nft_expr_priv(expr);
  	u32 queue, ret;
  
  	queue = regs->data[priv->sreg_qnum];
  
  	ret = NF_QUEUE_NR(queue);
  	if (priv->flags & NFT_QUEUE_FLAG_BYPASS)
  		ret |= NF_VERDICT_FLAG_QUEUE_BYPASS;
  
  	regs->verdict.code = ret;
  }

  static const struct nla_policy nft_queue_policy[NFTA_QUEUE_MAX + 1] = {
  	[NFTA_QUEUE_NUM]	= { .type = NLA_U16 },
  	[NFTA_QUEUE_TOTAL]	= { .type = NLA_U16 },
  	[NFTA_QUEUE_FLAGS]	= { .type = NLA_U16 },

  	[NFTA_QUEUE_SREG_QNUM]	= { .type = NLA_U32 },

  };
  
  static int nft_queue_init(const struct nft_ctx *ctx,

  			  const struct nft_expr *expr,
  			  const struct nlattr * const tb[])

  {
  	struct nft_queue *priv = nft_expr_priv(expr);

  	u32 maxid;

  	priv->queuenum = ntohs(nla_get_be16(tb[NFTA_QUEUE_NUM]));

  	if (tb[NFTA_QUEUE_TOTAL])

  		priv->queues_total = ntohs(nla_get_be16(tb[NFTA_QUEUE_TOTAL]));

  	else
  		priv->queues_total = 1;
  
  	if (priv->queues_total == 0)
  		return -EINVAL;
  
  	maxid = priv->queues_total - 1 + priv->queuenum;
  	if (maxid > U16_MAX)
  		return -ERANGE;

  	if (tb[NFTA_QUEUE_FLAGS]) {
  		priv->flags = ntohs(nla_get_be16(tb[NFTA_QUEUE_FLAGS]));
  		if (priv->flags & ~NFT_QUEUE_FLAG_MASK)
  			return -EINVAL;
  	}
  	return 0;
  }
  
  static int nft_queue_sreg_init(const struct nft_ctx *ctx,
  			       const struct nft_expr *expr,
  			       const struct nlattr * const tb[])
  {
  	struct nft_queue *priv = nft_expr_priv(expr);
  	int err;
  
  	priv->sreg_qnum = nft_parse_register(tb[NFTA_QUEUE_SREG_QNUM]);
  	err = nft_validate_register_load(priv->sreg_qnum, sizeof(u32));
  	if (err < 0)
  		return err;
  
  	if (tb[NFTA_QUEUE_FLAGS]) {

  		priv->flags = ntohs(nla_get_be16(tb[NFTA_QUEUE_FLAGS]));
  		if (priv->flags & ~NFT_QUEUE_FLAG_MASK)
  			return -EINVAL;

  		if (priv->flags & NFT_QUEUE_FLAG_CPU_FANOUT)
  			return -EOPNOTSUPP;

  	}

  	return 0;
  }
  
  static int nft_queue_dump(struct sk_buff *skb, const struct nft_expr *expr)
  {
  	const struct nft_queue *priv = nft_expr_priv(expr);
  
  	if (nla_put_be16(skb, NFTA_QUEUE_NUM, htons(priv->queuenum)) ||
  	    nla_put_be16(skb, NFTA_QUEUE_TOTAL, htons(priv->queues_total)) ||
  	    nla_put_be16(skb, NFTA_QUEUE_FLAGS, htons(priv->flags)))
  		goto nla_put_failure;
  
  	return 0;
  
  nla_put_failure:
  	return -1;
  }

  static int
  nft_queue_sreg_dump(struct sk_buff *skb, const struct nft_expr *expr)
  {
  	const struct nft_queue *priv = nft_expr_priv(expr);
  
  	if (nft_dump_register(skb, NFTA_QUEUE_SREG_QNUM, priv->sreg_qnum) ||
  	    nla_put_be16(skb, NFTA_QUEUE_FLAGS, htons(priv->flags)))
  		goto nla_put_failure;
  
  	return 0;
  
  nla_put_failure:
  	return -1;
  }

  static struct nft_expr_type nft_queue_type;
  static const struct nft_expr_ops nft_queue_ops = {
  	.type		= &nft_queue_type,
  	.size		= NFT_EXPR_SIZE(sizeof(struct nft_queue)),
  	.eval		= nft_queue_eval,
  	.init		= nft_queue_init,
  	.dump		= nft_queue_dump,
  };

  static const struct nft_expr_ops nft_queue_sreg_ops = {
  	.type		= &nft_queue_type,
  	.size		= NFT_EXPR_SIZE(sizeof(struct nft_queue)),
  	.eval		= nft_queue_sreg_eval,
  	.init		= nft_queue_sreg_init,
  	.dump		= nft_queue_sreg_dump,
  };
  
  static const struct nft_expr_ops *
  nft_queue_select_ops(const struct nft_ctx *ctx,
  		     const struct nlattr * const tb[])
  {
  	if (tb[NFTA_QUEUE_NUM] && tb[NFTA_QUEUE_SREG_QNUM])
  		return ERR_PTR(-EINVAL);
  
  	init_hashrandom(&jhash_initval);
  
  	if (tb[NFTA_QUEUE_NUM])
  		return &nft_queue_ops;
  
  	if (tb[NFTA_QUEUE_SREG_QNUM])
  		return &nft_queue_sreg_ops;
  
  	return ERR_PTR(-EINVAL);
  }

  static struct nft_expr_type nft_queue_type __read_mostly = {
  	.name		= "queue",

  	.select_ops	= nft_queue_select_ops,

  	.policy		= nft_queue_policy,
  	.maxattr	= NFTA_QUEUE_MAX,
  	.owner		= THIS_MODULE,
  };
  
  static int __init nft_queue_module_init(void)
  {
  	return nft_register_expr(&nft_queue_type);
  }
  
  static void __exit nft_queue_module_exit(void)
  {
  	nft_unregister_expr(&nft_queue_type);
  }
  
  module_init(nft_queue_module_init);
  module_exit(nft_queue_module_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Eric Leblond <eric@regit.org>");
  MODULE_ALIAS_NFT_EXPR("queue");