// 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/seqlock.h>
  #include <linux/netlink.h>
  #include <linux/netfilter.h>
  #include <linux/netfilter/nf_tables.h>
  #include <net/netfilter/nf_tables.h>
  
  struct nft_counter {

  	s64		bytes;
  	s64		packets;

  };
  
  struct nft_counter_percpu_priv {

  	struct nft_counter __percpu *counter;

  };

  static DEFINE_PER_CPU(seqcount_t, nft_counter_seq);

  static inline void nft_counter_do_eval(struct nft_counter_percpu_priv *priv,
  				       struct nft_regs *regs,
  				       const struct nft_pktinfo *pkt)

  {

  	struct nft_counter *this_cpu;
  	seqcount_t *myseq;

  
  	local_bh_disable();
  	this_cpu = this_cpu_ptr(priv->counter);

  	myseq = this_cpu_ptr(&nft_counter_seq);
  
  	write_seqcount_begin(myseq);
  
  	this_cpu->bytes += pkt->skb->len;
  	this_cpu->packets++;
  
  	write_seqcount_end(myseq);

  	local_bh_enable();

  }

  static inline void nft_counter_obj_eval(struct nft_object *obj,
  					struct nft_regs *regs,
  					const struct nft_pktinfo *pkt)
  {
  	struct nft_counter_percpu_priv *priv = nft_obj_data(obj);
  
  	nft_counter_do_eval(priv, regs, pkt);
  }
  
  static int nft_counter_do_init(const struct nlattr * const tb[],
  			       struct nft_counter_percpu_priv *priv)
  {

  	struct nft_counter __percpu *cpu_stats;
  	struct nft_counter *this_cpu;

  	cpu_stats = alloc_percpu(struct nft_counter);

  	if (cpu_stats == NULL)
  		return -ENOMEM;
  
  	preempt_disable();
  	this_cpu = this_cpu_ptr(cpu_stats);
  	if (tb[NFTA_COUNTER_PACKETS]) {

  	        this_cpu->packets =

  			be64_to_cpu(nla_get_be64(tb[NFTA_COUNTER_PACKETS]));
  	}
  	if (tb[NFTA_COUNTER_BYTES]) {

  		this_cpu->bytes =

  			be64_to_cpu(nla_get_be64(tb[NFTA_COUNTER_BYTES]));
  	}
  	preempt_enable();
  	priv->counter = cpu_stats;
  	return 0;
  }

  static int nft_counter_obj_init(const struct nft_ctx *ctx,
  				const struct nlattr * const tb[],

  				struct nft_object *obj)
  {
  	struct nft_counter_percpu_priv *priv = nft_obj_data(obj);
  
  	return nft_counter_do_init(tb, priv);
  }
  
  static void nft_counter_do_destroy(struct nft_counter_percpu_priv *priv)
  {
  	free_percpu(priv->counter);
  }

  static void nft_counter_obj_destroy(const struct nft_ctx *ctx,
  				    struct nft_object *obj)

  {
  	struct nft_counter_percpu_priv *priv = nft_obj_data(obj);
  
  	nft_counter_do_destroy(priv);
  }

  static void nft_counter_reset(struct nft_counter_percpu_priv *priv,

  			      struct nft_counter *total)

  {

  	struct nft_counter *this_cpu;

  	local_bh_disable();
  	this_cpu = this_cpu_ptr(priv->counter);
  	this_cpu->packets -= total->packets;
  	this_cpu->bytes -= total->bytes;
  	local_bh_enable();

  }

  static void nft_counter_fetch(struct nft_counter_percpu_priv *priv,

  			      struct nft_counter *total)
  {

  	struct nft_counter *this_cpu;
  	const seqcount_t *myseq;

  	u64 bytes, packets;
  	unsigned int seq;
  	int cpu;
  
  	memset(total, 0, sizeof(*total));
  	for_each_possible_cpu(cpu) {

  		myseq = per_cpu_ptr(&nft_counter_seq, cpu);
  		this_cpu = per_cpu_ptr(priv->counter, cpu);

  		do {

  			seq	= read_seqcount_begin(myseq);
  			bytes	= this_cpu->bytes;
  			packets	= this_cpu->packets;
  		} while (read_seqcount_retry(myseq, seq));

  		total->bytes	+= bytes;
  		total->packets	+= packets;

  	}
  }

  static int nft_counter_do_dump(struct sk_buff *skb,

  			       struct nft_counter_percpu_priv *priv,

  			       bool reset)

  {

  	struct nft_counter total;

  	nft_counter_fetch(priv, &total);

  	if (nla_put_be64(skb, NFTA_COUNTER_BYTES, cpu_to_be64(total.bytes),
  			 NFTA_COUNTER_PAD) ||
  	    nla_put_be64(skb, NFTA_COUNTER_PACKETS, cpu_to_be64(total.packets),
  			 NFTA_COUNTER_PAD))

  		goto nla_put_failure;

  
  	if (reset)
  		nft_counter_reset(priv, &total);

  	return 0;
  
  nla_put_failure:
  	return -1;
  }

  static int nft_counter_obj_dump(struct sk_buff *skb,

  				struct nft_object *obj, bool reset)

  {

  	struct nft_counter_percpu_priv *priv = nft_obj_data(obj);

  	return nft_counter_do_dump(skb, priv, reset);

  }

  static const struct nla_policy nft_counter_policy[NFTA_COUNTER_MAX + 1] = {
  	[NFTA_COUNTER_PACKETS]	= { .type = NLA_U64 },
  	[NFTA_COUNTER_BYTES]	= { .type = NLA_U64 },
  };

  static struct nft_object_type nft_counter_obj_type;
  static const struct nft_object_ops nft_counter_obj_ops = {
  	.type		= &nft_counter_obj_type,

  	.size		= sizeof(struct nft_counter_percpu_priv),

  	.eval		= nft_counter_obj_eval,
  	.init		= nft_counter_obj_init,
  	.destroy	= nft_counter_obj_destroy,
  	.dump		= nft_counter_obj_dump,

  };
  
  static struct nft_object_type nft_counter_obj_type __read_mostly = {
  	.type		= NFT_OBJECT_COUNTER,
  	.ops		= &nft_counter_obj_ops,
  	.maxattr	= NFTA_COUNTER_MAX,
  	.policy		= nft_counter_policy,

  	.owner		= THIS_MODULE,
  };
  
  static void nft_counter_eval(const struct nft_expr *expr,
  			     struct nft_regs *regs,
  			     const struct nft_pktinfo *pkt)
  {
  	struct nft_counter_percpu_priv *priv = nft_expr_priv(expr);
  
  	nft_counter_do_eval(priv, regs, pkt);
  }
  
  static int nft_counter_dump(struct sk_buff *skb, const struct nft_expr *expr)
  {

  	struct nft_counter_percpu_priv *priv = nft_expr_priv(expr);

  	return nft_counter_do_dump(skb, priv, false);

  }

  static int nft_counter_init(const struct nft_ctx *ctx,
  			    const struct nft_expr *expr,
  			    const struct nlattr * const tb[])
  {

  	struct nft_counter_percpu_priv *priv = nft_expr_priv(expr);

  	return nft_counter_do_init(tb, priv);

  }

  static void nft_counter_destroy(const struct nft_ctx *ctx,
  				const struct nft_expr *expr)
  {
  	struct nft_counter_percpu_priv *priv = nft_expr_priv(expr);

  	nft_counter_do_destroy(priv);

  }

  static int nft_counter_clone(struct nft_expr *dst, const struct nft_expr *src)
  {
  	struct nft_counter_percpu_priv *priv = nft_expr_priv(src);
  	struct nft_counter_percpu_priv *priv_clone = nft_expr_priv(dst);

  	struct nft_counter __percpu *cpu_stats;
  	struct nft_counter *this_cpu;

  	struct nft_counter total;

  	nft_counter_fetch(priv, &total);

  	cpu_stats = alloc_percpu_gfp(struct nft_counter, GFP_ATOMIC);

  	if (cpu_stats == NULL)

  		return -ENOMEM;

  
  	preempt_disable();
  	this_cpu = this_cpu_ptr(cpu_stats);

  	this_cpu->packets = total.packets;
  	this_cpu->bytes = total.bytes;

  	preempt_enable();
  
  	priv_clone->counter = cpu_stats;
  	return 0;
  }

  static struct nft_expr_type nft_counter_type;
  static const struct nft_expr_ops nft_counter_ops = {
  	.type		= &nft_counter_type,

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

  	.eval		= nft_counter_eval,
  	.init		= nft_counter_init,

  	.destroy	= nft_counter_destroy,

  	.destroy_clone	= nft_counter_destroy,

  	.dump		= nft_counter_dump,

  	.clone		= nft_counter_clone,

  };

  static struct nft_expr_type nft_counter_type __read_mostly = {
  	.name		= "counter",
  	.ops		= &nft_counter_ops,
  	.policy		= nft_counter_policy,
  	.maxattr	= NFTA_COUNTER_MAX,

  	.flags		= NFT_EXPR_STATEFUL,

  	.owner		= THIS_MODULE,
  };

  static int __init nft_counter_module_init(void)
  {

  	int cpu, err;
  
  	for_each_possible_cpu(cpu)
  		seqcount_init(per_cpu_ptr(&nft_counter_seq, cpu));

  	err = nft_register_obj(&nft_counter_obj_type);

  	if (err < 0)
  		return err;
  
  	err = nft_register_expr(&nft_counter_type);
  	if (err < 0)
  		goto err1;
  
  	return 0;
  err1:

  	nft_unregister_obj(&nft_counter_obj_type);

  	return err;

  }
  
  static void __exit nft_counter_module_exit(void)
  {

  	nft_unregister_expr(&nft_counter_type);

  	nft_unregister_obj(&nft_counter_obj_type);

  }
  
  module_init(nft_counter_module_init);
  module_exit(nft_counter_module_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
  MODULE_ALIAS_NFT_EXPR("counter");

  MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_COUNTER);

  MODULE_DESCRIPTION("nftables counter rule support");