// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * tcp_diag.c	Module for monitoring TCP transport protocols sockets.
   *

   * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>

   */

  #include <linux/module.h>

  #include <linux/net.h>
  #include <linux/sock_diag.h>

  #include <linux/inet_diag.h>
  
  #include <linux/tcp.h>

  #include <net/netlink.h>

  #include <net/tcp.h>
  
  static void tcp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
  			      void *_info)
  {

  	struct tcp_info *info = _info;

  	if (inet_sk_state_load(sk) == TCP_LISTEN) {

  		r->idiag_rqueue = READ_ONCE(sk->sk_ack_backlog);

  		r->idiag_wqueue = READ_ONCE(sk->sk_max_ack_backlog);

  	} else if (sk->sk_type == SOCK_STREAM) {
  		const struct tcp_sock *tp = tcp_sk(sk);

  		r->idiag_rqueue = max_t(int, READ_ONCE(tp->rcv_nxt) -
  					     READ_ONCE(tp->copied_seq), 0);

  		r->idiag_wqueue = READ_ONCE(tp->write_seq) - tp->snd_una;

  	}

  	if (info)

  		tcp_get_info(sk, info);
  }

  #ifdef CONFIG_TCP_MD5SIG
  static void tcp_diag_md5sig_fill(struct tcp_diag_md5sig *info,
  				 const struct tcp_md5sig_key *key)
  {
  	info->tcpm_family = key->family;
  	info->tcpm_prefixlen = key->prefixlen;
  	info->tcpm_keylen = key->keylen;
  	memcpy(info->tcpm_key, key->key, key->keylen);
  
  	if (key->family == AF_INET)
  		info->tcpm_addr[0] = key->addr.a4.s_addr;
  	#if IS_ENABLED(CONFIG_IPV6)
  	else if (key->family == AF_INET6)
  		memcpy(&info->tcpm_addr, &key->addr.a6,
  		       sizeof(info->tcpm_addr));
  	#endif
  }
  
  static int tcp_diag_put_md5sig(struct sk_buff *skb,
  			       const struct tcp_md5sig_info *md5sig)
  {
  	const struct tcp_md5sig_key *key;
  	struct tcp_diag_md5sig *info;
  	struct nlattr *attr;
  	int md5sig_count = 0;
  
  	hlist_for_each_entry_rcu(key, &md5sig->head, node)
  		md5sig_count++;
  	if (md5sig_count == 0)
  		return 0;
  
  	attr = nla_reserve(skb, INET_DIAG_MD5SIG,
  			   md5sig_count * sizeof(struct tcp_diag_md5sig));
  	if (!attr)
  		return -EMSGSIZE;
  
  	info = nla_data(attr);
  	memset(info, 0, md5sig_count * sizeof(struct tcp_diag_md5sig));
  	hlist_for_each_entry_rcu(key, &md5sig->head, node) {
  		tcp_diag_md5sig_fill(info++, key);
  		if (--md5sig_count == 0)
  			break;
  	}
  
  	return 0;
  }
  #endif

  static int tcp_diag_put_ulp(struct sk_buff *skb, struct sock *sk,
  			    const struct tcp_ulp_ops *ulp_ops)
  {
  	struct nlattr *nest;
  	int err;
  
  	nest = nla_nest_start_noflag(skb, INET_DIAG_ULP_INFO);
  	if (!nest)
  		return -EMSGSIZE;
  
  	err = nla_put_string(skb, INET_ULP_INFO_NAME, ulp_ops->name);
  	if (err)
  		goto nla_failure;
  
  	if (ulp_ops->get_info)
  		err = ulp_ops->get_info(sk, skb);
  	if (err)
  		goto nla_failure;
  
  	nla_nest_end(skb, nest);
  	return 0;
  
  nla_failure:
  	nla_nest_cancel(skb, nest);
  	return err;
  }

  static int tcp_diag_get_aux(struct sock *sk, bool net_admin,
  			    struct sk_buff *skb)
  {

  	struct inet_connection_sock *icsk = inet_csk(sk);
  	int err = 0;

  #ifdef CONFIG_TCP_MD5SIG
  	if (net_admin) {
  		struct tcp_md5sig_info *md5sig;

  
  		rcu_read_lock();
  		md5sig = rcu_dereference(tcp_sk(sk)->md5sig_info);
  		if (md5sig)
  			err = tcp_diag_put_md5sig(skb, md5sig);
  		rcu_read_unlock();
  		if (err < 0)
  			return err;
  	}
  #endif

  	if (net_admin) {
  		const struct tcp_ulp_ops *ulp_ops;
  
  		ulp_ops = icsk->icsk_ulp_ops;
  		if (ulp_ops)
  			err = tcp_diag_put_ulp(skb, sk, ulp_ops);
  		if (err)
  			return err;
  	}

  	return 0;
  }
  
  static size_t tcp_diag_get_aux_size(struct sock *sk, bool net_admin)
  {

  	struct inet_connection_sock *icsk = inet_csk(sk);

  	size_t size = 0;
  
  #ifdef CONFIG_TCP_MD5SIG
  	if (net_admin && sk_fullsock(sk)) {
  		const struct tcp_md5sig_info *md5sig;
  		const struct tcp_md5sig_key *key;
  		size_t md5sig_count = 0;
  
  		rcu_read_lock();
  		md5sig = rcu_dereference(tcp_sk(sk)->md5sig_info);
  		if (md5sig) {
  			hlist_for_each_entry_rcu(key, &md5sig->head, node)
  				md5sig_count++;
  		}
  		rcu_read_unlock();
  		size += nla_total_size(md5sig_count *
  				       sizeof(struct tcp_diag_md5sig));
  	}
  #endif

  	if (net_admin && sk_fullsock(sk)) {

  		const struct tcp_ulp_ops *ulp_ops;
  
  		ulp_ops = icsk->icsk_ulp_ops;
  		if (ulp_ops) {
  			size += nla_total_size(0) +
  				nla_total_size(TCP_ULP_NAME_MAX);
  			if (ulp_ops->get_info_size)
  				size += ulp_ops->get_info_size(sk);
  		}
  	}

  	return size;
  }

  static void tcp_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,

  			  const struct inet_diag_req_v2 *r)

  {

  	inet_diag_dump_icsk(&tcp_hashinfo, skb, cb, r);

  }

  static int tcp_diag_dump_one(struct netlink_callback *cb,

  			     const struct inet_diag_req_v2 *req)

  {

  	return inet_diag_dump_one_icsk(&tcp_hashinfo, cb, req);

  }

  #ifdef CONFIG_INET_DIAG_DESTROY
  static int tcp_diag_destroy(struct sk_buff *in_skb,
  			    const struct inet_diag_req_v2 *req)
  {
  	struct net *net = sock_net(in_skb->sk);
  	struct sock *sk = inet_diag_find_one_icsk(net, &tcp_hashinfo, req);

  	int err;

  
  	if (IS_ERR(sk))
  		return PTR_ERR(sk);

  	err = sock_diag_destroy(sk, ECONNABORTED);
  
  	sock_gen_put(sk);
  
  	return err;

  }
  #endif

  static const struct inet_diag_handler tcp_diag_handler = {

  	.dump			= tcp_diag_dump,
  	.dump_one		= tcp_diag_dump_one,
  	.idiag_get_info		= tcp_diag_get_info,
  	.idiag_get_aux		= tcp_diag_get_aux,
  	.idiag_get_aux_size	= tcp_diag_get_aux_size,
  	.idiag_type		= IPPROTO_TCP,
  	.idiag_info_size	= sizeof(struct tcp_info),

  #ifdef CONFIG_INET_DIAG_DESTROY

  	.destroy		= tcp_diag_destroy,

  #endif

  };
  
  static int __init tcp_diag_init(void)
  {
  	return inet_diag_register(&tcp_diag_handler);
  }
  
  static void __exit tcp_diag_exit(void)
  {
  	inet_diag_unregister(&tcp_diag_handler);
  }
  
  module_init(tcp_diag_init);
  module_exit(tcp_diag_exit);
  MODULE_LICENSE("GPL");

  MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 2-6 /* AF_INET - IPPROTO_TCP */);