/*
   * L2TP netlink layer, for management
   *
   * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
   *
   * Partly based on the IrDA nelink implementation
   * (see net/irda/irnetlink.c) which is:
   * Copyright (c) 2007 Samuel Ortiz <samuel@sortiz.org>
   * which is in turn partly based on the wireless netlink code:
   * Copyright 2006 Johannes Berg <johannes@sipsolutions.net>
   *
   * 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.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <net/sock.h>
  #include <net/genetlink.h>
  #include <net/udp.h>
  #include <linux/in.h>
  #include <linux/udp.h>
  #include <linux/socket.h>
  #include <linux/module.h>
  #include <linux/list.h>
  #include <net/net_namespace.h>
  
  #include <linux/l2tp.h>
  
  #include "l2tp_core.h"

  static struct genl_family l2tp_nl_family;

  static const struct genl_multicast_group l2tp_multicast_group[] = {
  	{
  		.name = L2TP_GENL_MCGROUP,
  	},
  };
  
  static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 portid, u32 seq,
  			       int flags, struct l2tp_tunnel *tunnel, u8 cmd);
  static int l2tp_nl_session_send(struct sk_buff *skb, u32 portid, u32 seq,
  				int flags, struct l2tp_session *session,
  				u8 cmd);

  /* Accessed under genl lock */
  static const struct l2tp_nl_cmd_ops *l2tp_nl_cmd_ops[__L2TP_PWTYPE_MAX];

  static struct l2tp_session *l2tp_nl_session_get(struct genl_info *info,
  						bool do_ref)

  {
  	u32 tunnel_id;
  	u32 session_id;
  	char *ifname;
  	struct l2tp_tunnel *tunnel;
  	struct l2tp_session *session = NULL;
  	struct net *net = genl_info_net(info);
  
  	if (info->attrs[L2TP_ATTR_IFNAME]) {
  		ifname = nla_data(info->attrs[L2TP_ATTR_IFNAME]);

  		session = l2tp_session_get_by_ifname(net, ifname, do_ref);

  	} else if ((info->attrs[L2TP_ATTR_SESSION_ID]) &&
  		   (info->attrs[L2TP_ATTR_CONN_ID])) {
  		tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]);
  		session_id = nla_get_u32(info->attrs[L2TP_ATTR_SESSION_ID]);

  		tunnel = l2tp_tunnel_get(net, tunnel_id);
  		if (tunnel) {

  			session = l2tp_session_get(net, tunnel, session_id,
  						   do_ref);

  			l2tp_tunnel_dec_refcount(tunnel);
  		}

  	}
  
  	return session;
  }
  
  static int l2tp_nl_cmd_noop(struct sk_buff *skb, struct genl_info *info)
  {
  	struct sk_buff *msg;
  	void *hdr;
  	int ret = -ENOBUFS;

  	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);

  	if (!msg) {
  		ret = -ENOMEM;
  		goto out;
  	}

  	hdr = genlmsg_put(msg, info->snd_portid, info->snd_seq,

  			  &l2tp_nl_family, 0, L2TP_CMD_NOOP);

  	if (!hdr) {
  		ret = -EMSGSIZE;

  		goto err_out;
  	}
  
  	genlmsg_end(msg, hdr);

  	return genlmsg_unicast(genl_info_net(info), msg, info->snd_portid);

  
  err_out:
  	nlmsg_free(msg);
  
  out:
  	return ret;
  }

  static int l2tp_tunnel_notify(struct genl_family *family,
  			      struct genl_info *info,
  			      struct l2tp_tunnel *tunnel,
  			      u8 cmd)
  {
  	struct sk_buff *msg;
  	int ret;
  
  	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
  	if (!msg)
  		return -ENOMEM;
  
  	ret = l2tp_nl_tunnel_send(msg, info->snd_portid, info->snd_seq,
  				  NLM_F_ACK, tunnel, cmd);

  	if (ret >= 0) {
  		ret = genlmsg_multicast_allns(family, msg, 0, 0, GFP_ATOMIC);
  		/* We don't care if no one is listening */
  		if (ret == -ESRCH)
  			ret = 0;
  		return ret;
  	}

  
  	nlmsg_free(msg);
  
  	return ret;
  }
  
  static int l2tp_session_notify(struct genl_family *family,
  			       struct genl_info *info,
  			       struct l2tp_session *session,
  			       u8 cmd)
  {
  	struct sk_buff *msg;
  	int ret;
  
  	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
  	if (!msg)
  		return -ENOMEM;
  
  	ret = l2tp_nl_session_send(msg, info->snd_portid, info->snd_seq,
  				   NLM_F_ACK, session, cmd);

  	if (ret >= 0) {
  		ret = genlmsg_multicast_allns(family, msg, 0, 0, GFP_ATOMIC);
  		/* We don't care if no one is listening */
  		if (ret == -ESRCH)
  			ret = 0;
  		return ret;
  	}

  
  	nlmsg_free(msg);
  
  	return ret;
  }

  static int l2tp_nl_cmd_tunnel_create(struct sk_buff *skb, struct genl_info *info)
  {
  	u32 tunnel_id;
  	u32 peer_tunnel_id;
  	int proto_version;
  	int fd;
  	int ret = 0;
  	struct l2tp_tunnel_cfg cfg = { 0, };
  	struct l2tp_tunnel *tunnel;
  	struct net *net = genl_info_net(info);
  
  	if (!info->attrs[L2TP_ATTR_CONN_ID]) {
  		ret = -EINVAL;
  		goto out;
  	}
  	tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]);
  
  	if (!info->attrs[L2TP_ATTR_PEER_CONN_ID]) {
  		ret = -EINVAL;
  		goto out;
  	}
  	peer_tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_PEER_CONN_ID]);
  
  	if (!info->attrs[L2TP_ATTR_PROTO_VERSION]) {
  		ret = -EINVAL;
  		goto out;
  	}
  	proto_version = nla_get_u8(info->attrs[L2TP_ATTR_PROTO_VERSION]);
  
  	if (!info->attrs[L2TP_ATTR_ENCAP_TYPE]) {
  		ret = -EINVAL;
  		goto out;
  	}
  	cfg.encap = nla_get_u16(info->attrs[L2TP_ATTR_ENCAP_TYPE]);

  	fd = -1;
  	if (info->attrs[L2TP_ATTR_FD]) {
  		fd = nla_get_u32(info->attrs[L2TP_ATTR_FD]);
  	} else {

  #if IS_ENABLED(CONFIG_IPV6)
  		if (info->attrs[L2TP_ATTR_IP6_SADDR] &&
  		    info->attrs[L2TP_ATTR_IP6_DADDR]) {
  			cfg.local_ip6 = nla_data(
  				info->attrs[L2TP_ATTR_IP6_SADDR]);
  			cfg.peer_ip6 = nla_data(
  				info->attrs[L2TP_ATTR_IP6_DADDR]);
  		} else
  #endif
  		if (info->attrs[L2TP_ATTR_IP_SADDR] &&
  		    info->attrs[L2TP_ATTR_IP_DADDR]) {

  			cfg.local_ip.s_addr = nla_get_in_addr(

  				info->attrs[L2TP_ATTR_IP_SADDR]);

  			cfg.peer_ip.s_addr = nla_get_in_addr(

  				info->attrs[L2TP_ATTR_IP_DADDR]);
  		} else {
  			ret = -EINVAL;
  			goto out;
  		}

  		if (info->attrs[L2TP_ATTR_UDP_SPORT])
  			cfg.local_udp_port = nla_get_u16(info->attrs[L2TP_ATTR_UDP_SPORT]);
  		if (info->attrs[L2TP_ATTR_UDP_DPORT])
  			cfg.peer_udp_port = nla_get_u16(info->attrs[L2TP_ATTR_UDP_DPORT]);

  		cfg.use_udp_checksums = nla_get_flag(
  			info->attrs[L2TP_ATTR_UDP_CSUM]);

  
  #if IS_ENABLED(CONFIG_IPV6)

  		cfg.udp6_zero_tx_checksums = nla_get_flag(
  			info->attrs[L2TP_ATTR_UDP_ZERO_CSUM6_TX]);
  		cfg.udp6_zero_rx_checksums = nla_get_flag(
  			info->attrs[L2TP_ATTR_UDP_ZERO_CSUM6_RX]);

  #endif

  	}

  
  	if (info->attrs[L2TP_ATTR_DEBUG])
  		cfg.debug = nla_get_u32(info->attrs[L2TP_ATTR_DEBUG]);
  
  	tunnel = l2tp_tunnel_find(net, tunnel_id);
  	if (tunnel != NULL) {
  		ret = -EEXIST;
  		goto out;
  	}
  
  	ret = -EINVAL;
  	switch (cfg.encap) {
  	case L2TP_ENCAPTYPE_UDP:
  	case L2TP_ENCAPTYPE_IP:
  		ret = l2tp_tunnel_create(net, fd, proto_version, tunnel_id,
  					 peer_tunnel_id, &cfg, &tunnel);
  		break;
  	}

  	if (ret >= 0)
  		ret = l2tp_tunnel_notify(&l2tp_nl_family, info,
  					 tunnel, L2TP_CMD_TUNNEL_CREATE);

  out:
  	return ret;
  }
  
  static int l2tp_nl_cmd_tunnel_delete(struct sk_buff *skb, struct genl_info *info)
  {
  	struct l2tp_tunnel *tunnel;
  	u32 tunnel_id;
  	int ret = 0;
  	struct net *net = genl_info_net(info);
  
  	if (!info->attrs[L2TP_ATTR_CONN_ID]) {
  		ret = -EINVAL;
  		goto out;
  	}
  	tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]);

  	tunnel = l2tp_tunnel_get(net, tunnel_id);
  	if (!tunnel) {

  		ret = -ENODEV;
  		goto out;
  	}

  	l2tp_tunnel_notify(&l2tp_nl_family, info,
  			   tunnel, L2TP_CMD_TUNNEL_DELETE);

  	l2tp_tunnel_delete(tunnel);

  	l2tp_tunnel_dec_refcount(tunnel);

  out:
  	return ret;
  }
  
  static int l2tp_nl_cmd_tunnel_modify(struct sk_buff *skb, struct genl_info *info)
  {
  	struct l2tp_tunnel *tunnel;
  	u32 tunnel_id;
  	int ret = 0;
  	struct net *net = genl_info_net(info);
  
  	if (!info->attrs[L2TP_ATTR_CONN_ID]) {
  		ret = -EINVAL;
  		goto out;
  	}
  	tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]);

  	tunnel = l2tp_tunnel_get(net, tunnel_id);
  	if (!tunnel) {

  		ret = -ENODEV;
  		goto out;
  	}
  
  	if (info->attrs[L2TP_ATTR_DEBUG])
  		tunnel->debug = nla_get_u32(info->attrs[L2TP_ATTR_DEBUG]);

  	ret = l2tp_tunnel_notify(&l2tp_nl_family, info,
  				 tunnel, L2TP_CMD_TUNNEL_MODIFY);

  	l2tp_tunnel_dec_refcount(tunnel);

  out:
  	return ret;
  }

  static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 portid, u32 seq, int flags,

  			       struct l2tp_tunnel *tunnel, u8 cmd)

  {
  	void *hdr;
  	struct nlattr *nest;
  	struct sock *sk = NULL;
  	struct inet_sock *inet;

  #if IS_ENABLED(CONFIG_IPV6)
  	struct ipv6_pinfo *np = NULL;
  #endif

  	hdr = genlmsg_put(skb, portid, seq, &l2tp_nl_family, flags, cmd);

  	if (!hdr)
  		return -EMSGSIZE;

  	if (nla_put_u8(skb, L2TP_ATTR_PROTO_VERSION, tunnel->version) ||
  	    nla_put_u32(skb, L2TP_ATTR_CONN_ID, tunnel->tunnel_id) ||
  	    nla_put_u32(skb, L2TP_ATTR_PEER_CONN_ID, tunnel->peer_tunnel_id) ||
  	    nla_put_u32(skb, L2TP_ATTR_DEBUG, tunnel->debug) ||
  	    nla_put_u16(skb, L2TP_ATTR_ENCAP_TYPE, tunnel->encap))
  		goto nla_put_failure;

  
  	nest = nla_nest_start(skb, L2TP_ATTR_STATS);
  	if (nest == NULL)
  		goto nla_put_failure;

  	if (nla_put_u64_64bit(skb, L2TP_ATTR_TX_PACKETS,
  			      atomic_long_read(&tunnel->stats.tx_packets),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_TX_BYTES,
  			      atomic_long_read(&tunnel->stats.tx_bytes),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_TX_ERRORS,
  			      atomic_long_read(&tunnel->stats.tx_errors),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_RX_PACKETS,
  			      atomic_long_read(&tunnel->stats.rx_packets),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_RX_BYTES,
  			      atomic_long_read(&tunnel->stats.rx_bytes),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_RX_SEQ_DISCARDS,
  			      atomic_long_read(&tunnel->stats.rx_seq_discards),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_RX_OOS_PACKETS,
  			      atomic_long_read(&tunnel->stats.rx_oos_packets),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_RX_ERRORS,
  			      atomic_long_read(&tunnel->stats.rx_errors),
  			      L2TP_ATTR_STATS_PAD))

  		goto nla_put_failure;

  	nla_nest_end(skb, nest);
  
  	sk = tunnel->sock;
  	if (!sk)
  		goto out;

  #if IS_ENABLED(CONFIG_IPV6)
  	if (sk->sk_family == AF_INET6)
  		np = inet6_sk(sk);
  #endif

  	inet = inet_sk(sk);
  
  	switch (tunnel->encap) {
  	case L2TP_ENCAPTYPE_UDP:

  		switch (sk->sk_family) {
  		case AF_INET:
  			if (nla_put_u8(skb, L2TP_ATTR_UDP_CSUM, !sk->sk_no_check_tx))
  				goto nla_put_failure;
  			break;

  #if IS_ENABLED(CONFIG_IPV6)
  		case AF_INET6:
  			if (udp_get_no_check6_tx(sk) &&
  			    nla_put_flag(skb, L2TP_ATTR_UDP_ZERO_CSUM6_TX))
  				goto nla_put_failure;
  			if (udp_get_no_check6_rx(sk) &&
  			    nla_put_flag(skb, L2TP_ATTR_UDP_ZERO_CSUM6_RX))
  				goto nla_put_failure;
  			break;
  #endif

  		}

  		if (nla_put_u16(skb, L2TP_ATTR_UDP_SPORT, ntohs(inet->inet_sport)) ||

  		    nla_put_u16(skb, L2TP_ATTR_UDP_DPORT, ntohs(inet->inet_dport)))

  			goto nla_put_failure;

  		/* NOBREAK */
  	case L2TP_ENCAPTYPE_IP:

  #if IS_ENABLED(CONFIG_IPV6)
  		if (np) {

  			if (nla_put_in6_addr(skb, L2TP_ATTR_IP6_SADDR,
  					     &np->saddr) ||
  			    nla_put_in6_addr(skb, L2TP_ATTR_IP6_DADDR,
  					     &sk->sk_v6_daddr))

  				goto nla_put_failure;
  		} else
  #endif

  		if (nla_put_in_addr(skb, L2TP_ATTR_IP_SADDR,
  				    inet->inet_saddr) ||
  		    nla_put_in_addr(skb, L2TP_ATTR_IP_DADDR,
  				    inet->inet_daddr))

  			goto nla_put_failure;

  		break;
  	}
  
  out:

  	genlmsg_end(skb, hdr);
  	return 0;

  
  nla_put_failure:
  	genlmsg_cancel(skb, hdr);
  	return -1;
  }
  
  static int l2tp_nl_cmd_tunnel_get(struct sk_buff *skb, struct genl_info *info)
  {
  	struct l2tp_tunnel *tunnel;
  	struct sk_buff *msg;
  	u32 tunnel_id;
  	int ret = -ENOBUFS;
  	struct net *net = genl_info_net(info);
  
  	if (!info->attrs[L2TP_ATTR_CONN_ID]) {
  		ret = -EINVAL;

  		goto err;

  	}
  
  	tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]);

  	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);

  	if (!msg) {
  		ret = -ENOMEM;

  		goto err;
  	}
  
  	tunnel = l2tp_tunnel_get(net, tunnel_id);
  	if (!tunnel) {
  		ret = -ENODEV;
  		goto err_nlmsg;

  	}

  	ret = l2tp_nl_tunnel_send(msg, info->snd_portid, info->snd_seq,

  				  NLM_F_ACK, tunnel, L2TP_CMD_TUNNEL_GET);

  	if (ret < 0)

  		goto err_nlmsg_tunnel;
  
  	l2tp_tunnel_dec_refcount(tunnel);

  	return genlmsg_unicast(net, msg, info->snd_portid);

  err_nlmsg_tunnel:
  	l2tp_tunnel_dec_refcount(tunnel);
  err_nlmsg:

  	nlmsg_free(msg);

  err:

  	return ret;
  }
  
  static int l2tp_nl_cmd_tunnel_dump(struct sk_buff *skb, struct netlink_callback *cb)
  {
  	int ti = cb->args[0];
  	struct l2tp_tunnel *tunnel;
  	struct net *net = sock_net(skb->sk);
  
  	for (;;) {
  		tunnel = l2tp_tunnel_find_nth(net, ti);
  		if (tunnel == NULL)
  			goto out;

  		if (l2tp_nl_tunnel_send(skb, NETLINK_CB(cb->skb).portid,

  					cb->nlh->nlmsg_seq, NLM_F_MULTI,

  					tunnel, L2TP_CMD_TUNNEL_GET) < 0)

  			goto out;
  
  		ti++;
  	}
  
  out:
  	cb->args[0] = ti;
  
  	return skb->len;
  }
  
  static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *info)
  {
  	u32 tunnel_id = 0;
  	u32 session_id;
  	u32 peer_session_id;
  	int ret = 0;
  	struct l2tp_tunnel *tunnel;
  	struct l2tp_session *session;
  	struct l2tp_session_cfg cfg = { 0, };
  	struct net *net = genl_info_net(info);
  
  	if (!info->attrs[L2TP_ATTR_CONN_ID]) {
  		ret = -EINVAL;
  		goto out;
  	}

  	tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]);

  	tunnel = l2tp_tunnel_get(net, tunnel_id);

  	if (!tunnel) {
  		ret = -ENODEV;
  		goto out;
  	}
  
  	if (!info->attrs[L2TP_ATTR_SESSION_ID]) {
  		ret = -EINVAL;

  		goto out_tunnel;

  	}
  	session_id = nla_get_u32(info->attrs[L2TP_ATTR_SESSION_ID]);

  
  	if (!info->attrs[L2TP_ATTR_PEER_SESSION_ID]) {
  		ret = -EINVAL;

  		goto out_tunnel;

  	}
  	peer_session_id = nla_get_u32(info->attrs[L2TP_ATTR_PEER_SESSION_ID]);
  
  	if (!info->attrs[L2TP_ATTR_PW_TYPE]) {
  		ret = -EINVAL;

  		goto out_tunnel;

  	}
  	cfg.pw_type = nla_get_u16(info->attrs[L2TP_ATTR_PW_TYPE]);
  	if (cfg.pw_type >= __L2TP_PWTYPE_MAX) {
  		ret = -EINVAL;

  		goto out_tunnel;

  	}
  
  	if (tunnel->version > 2) {
  		if (info->attrs[L2TP_ATTR_OFFSET])
  			cfg.offset = nla_get_u16(info->attrs[L2TP_ATTR_OFFSET]);
  
  		if (info->attrs[L2TP_ATTR_DATA_SEQ])
  			cfg.data_seq = nla_get_u8(info->attrs[L2TP_ATTR_DATA_SEQ]);
  
  		cfg.l2specific_type = L2TP_L2SPECTYPE_DEFAULT;
  		if (info->attrs[L2TP_ATTR_L2SPEC_TYPE])
  			cfg.l2specific_type = nla_get_u8(info->attrs[L2TP_ATTR_L2SPEC_TYPE]);
  
  		cfg.l2specific_len = 4;
  		if (info->attrs[L2TP_ATTR_L2SPEC_LEN])
  			cfg.l2specific_len = nla_get_u8(info->attrs[L2TP_ATTR_L2SPEC_LEN]);
  
  		if (info->attrs[L2TP_ATTR_COOKIE]) {
  			u16 len = nla_len(info->attrs[L2TP_ATTR_COOKIE]);
  			if (len > 8) {
  				ret = -EINVAL;

  				goto out_tunnel;

  			}
  			cfg.cookie_len = len;
  			memcpy(&cfg.cookie[0], nla_data(info->attrs[L2TP_ATTR_COOKIE]), len);
  		}
  		if (info->attrs[L2TP_ATTR_PEER_COOKIE]) {
  			u16 len = nla_len(info->attrs[L2TP_ATTR_PEER_COOKIE]);
  			if (len > 8) {
  				ret = -EINVAL;

  				goto out_tunnel;

  			}
  			cfg.peer_cookie_len = len;
  			memcpy(&cfg.peer_cookie[0], nla_data(info->attrs[L2TP_ATTR_PEER_COOKIE]), len);
  		}
  		if (info->attrs[L2TP_ATTR_IFNAME])
  			cfg.ifname = nla_data(info->attrs[L2TP_ATTR_IFNAME]);
  
  		if (info->attrs[L2TP_ATTR_VLAN_ID])
  			cfg.vlan_id = nla_get_u16(info->attrs[L2TP_ATTR_VLAN_ID]);
  	}
  
  	if (info->attrs[L2TP_ATTR_DEBUG])
  		cfg.debug = nla_get_u32(info->attrs[L2TP_ATTR_DEBUG]);
  
  	if (info->attrs[L2TP_ATTR_RECV_SEQ])
  		cfg.recv_seq = nla_get_u8(info->attrs[L2TP_ATTR_RECV_SEQ]);
  
  	if (info->attrs[L2TP_ATTR_SEND_SEQ])
  		cfg.send_seq = nla_get_u8(info->attrs[L2TP_ATTR_SEND_SEQ]);
  
  	if (info->attrs[L2TP_ATTR_LNS_MODE])
  		cfg.lns_mode = nla_get_u8(info->attrs[L2TP_ATTR_LNS_MODE]);
  
  	if (info->attrs[L2TP_ATTR_RECV_TIMEOUT])
  		cfg.reorder_timeout = nla_get_msecs(info->attrs[L2TP_ATTR_RECV_TIMEOUT]);
  
  	if (info->attrs[L2TP_ATTR_MTU])
  		cfg.mtu = nla_get_u16(info->attrs[L2TP_ATTR_MTU]);
  
  	if (info->attrs[L2TP_ATTR_MRU])
  		cfg.mru = nla_get_u16(info->attrs[L2TP_ATTR_MRU]);

  #ifdef CONFIG_MODULES
  	if (l2tp_nl_cmd_ops[cfg.pw_type] == NULL) {
  		genl_unlock();
  		request_module("net-l2tp-type-%u", cfg.pw_type);
  		genl_lock();
  	}
  #endif

  	if ((l2tp_nl_cmd_ops[cfg.pw_type] == NULL) ||
  	    (l2tp_nl_cmd_ops[cfg.pw_type]->session_create == NULL)) {
  		ret = -EPROTONOSUPPORT;

  		goto out_tunnel;

  	}
  
  	/* Check that pseudowire-specific params are present */
  	switch (cfg.pw_type) {
  	case L2TP_PWTYPE_NONE:
  		break;
  	case L2TP_PWTYPE_ETH_VLAN:
  		if (!info->attrs[L2TP_ATTR_VLAN_ID]) {
  			ret = -EINVAL;

  			goto out_tunnel;

  		}
  		break;
  	case L2TP_PWTYPE_ETH:
  		break;
  	case L2TP_PWTYPE_PPP:
  	case L2TP_PWTYPE_PPP_AC:
  		break;
  	case L2TP_PWTYPE_IP:
  	default:
  		ret = -EPROTONOSUPPORT;
  		break;
  	}

  	ret = l2tp_nl_cmd_ops[cfg.pw_type]->session_create(net, tunnel,
  							   session_id,
  							   peer_session_id,
  							   &cfg);

  	if (ret >= 0) {

  		session = l2tp_session_get(net, tunnel, session_id, false);
  		if (session) {

  			ret = l2tp_session_notify(&l2tp_nl_family, info, session,
  						  L2TP_CMD_SESSION_CREATE);

  			l2tp_session_dec_refcount(session);
  		}

  	}

  out_tunnel:
  	l2tp_tunnel_dec_refcount(tunnel);

  out:
  	return ret;
  }
  
  static int l2tp_nl_cmd_session_delete(struct sk_buff *skb, struct genl_info *info)
  {
  	int ret = 0;
  	struct l2tp_session *session;
  	u16 pw_type;

  	session = l2tp_nl_session_get(info, true);

  	if (session == NULL) {
  		ret = -ENODEV;
  		goto out;
  	}

  	l2tp_session_notify(&l2tp_nl_family, info,
  			    session, L2TP_CMD_SESSION_DELETE);

  	pw_type = session->pwtype;
  	if (pw_type < __L2TP_PWTYPE_MAX)
  		if (l2tp_nl_cmd_ops[pw_type] && l2tp_nl_cmd_ops[pw_type]->session_delete)
  			ret = (*l2tp_nl_cmd_ops[pw_type]->session_delete)(session);

  	if (session->deref)
  		session->deref(session);
  	l2tp_session_dec_refcount(session);

  out:
  	return ret;
  }
  
  static int l2tp_nl_cmd_session_modify(struct sk_buff *skb, struct genl_info *info)
  {
  	int ret = 0;
  	struct l2tp_session *session;

  	session = l2tp_nl_session_get(info, false);

  	if (session == NULL) {
  		ret = -ENODEV;
  		goto out;
  	}
  
  	if (info->attrs[L2TP_ATTR_DEBUG])
  		session->debug = nla_get_u32(info->attrs[L2TP_ATTR_DEBUG]);
  
  	if (info->attrs[L2TP_ATTR_DATA_SEQ])
  		session->data_seq = nla_get_u8(info->attrs[L2TP_ATTR_DATA_SEQ]);
  
  	if (info->attrs[L2TP_ATTR_RECV_SEQ])
  		session->recv_seq = nla_get_u8(info->attrs[L2TP_ATTR_RECV_SEQ]);

  	if (info->attrs[L2TP_ATTR_SEND_SEQ]) {

  		session->send_seq = nla_get_u8(info->attrs[L2TP_ATTR_SEND_SEQ]);

  		l2tp_session_set_header_len(session, session->tunnel->version);
  	}

  
  	if (info->attrs[L2TP_ATTR_LNS_MODE])
  		session->lns_mode = nla_get_u8(info->attrs[L2TP_ATTR_LNS_MODE]);
  
  	if (info->attrs[L2TP_ATTR_RECV_TIMEOUT])
  		session->reorder_timeout = nla_get_msecs(info->attrs[L2TP_ATTR_RECV_TIMEOUT]);
  
  	if (info->attrs[L2TP_ATTR_MTU])
  		session->mtu = nla_get_u16(info->attrs[L2TP_ATTR_MTU]);
  
  	if (info->attrs[L2TP_ATTR_MRU])
  		session->mru = nla_get_u16(info->attrs[L2TP_ATTR_MRU]);

  	ret = l2tp_session_notify(&l2tp_nl_family, info,
  				  session, L2TP_CMD_SESSION_MODIFY);

  	l2tp_session_dec_refcount(session);

  out:
  	return ret;
  }

  static int l2tp_nl_session_send(struct sk_buff *skb, u32 portid, u32 seq, int flags,

  				struct l2tp_session *session, u8 cmd)

  {
  	void *hdr;
  	struct nlattr *nest;
  	struct l2tp_tunnel *tunnel = session->tunnel;
  	struct sock *sk = NULL;
  
  	sk = tunnel->sock;

  	hdr = genlmsg_put(skb, portid, seq, &l2tp_nl_family, flags, cmd);

  	if (!hdr)
  		return -EMSGSIZE;

  	if (nla_put_u32(skb, L2TP_ATTR_CONN_ID, tunnel->tunnel_id) ||
  	    nla_put_u32(skb, L2TP_ATTR_SESSION_ID, session->session_id) ||
  	    nla_put_u32(skb, L2TP_ATTR_PEER_CONN_ID, tunnel->peer_tunnel_id) ||
  	    nla_put_u32(skb, L2TP_ATTR_PEER_SESSION_ID,
  			session->peer_session_id) ||
  	    nla_put_u32(skb, L2TP_ATTR_DEBUG, session->debug) ||
  	    nla_put_u16(skb, L2TP_ATTR_PW_TYPE, session->pwtype) ||
  	    nla_put_u16(skb, L2TP_ATTR_MTU, session->mtu) ||
  	    (session->mru &&
  	     nla_put_u16(skb, L2TP_ATTR_MRU, session->mru)))
  		goto nla_put_failure;

  	if ((session->ifname[0] &&

  	     nla_put_string(skb, L2TP_ATTR_IFNAME, session->ifname)) ||
  	    (session->cookie_len &&
  	     nla_put(skb, L2TP_ATTR_COOKIE, session->cookie_len,
  		     &session->cookie[0])) ||
  	    (session->peer_cookie_len &&
  	     nla_put(skb, L2TP_ATTR_PEER_COOKIE, session->peer_cookie_len,
  		     &session->peer_cookie[0])) ||
  	    nla_put_u8(skb, L2TP_ATTR_RECV_SEQ, session->recv_seq) ||
  	    nla_put_u8(skb, L2TP_ATTR_SEND_SEQ, session->send_seq) ||
  	    nla_put_u8(skb, L2TP_ATTR_LNS_MODE, session->lns_mode) ||

  #ifdef CONFIG_XFRM

  	    (((sk) && (sk->sk_policy[0] || sk->sk_policy[1])) &&
  	     nla_put_u8(skb, L2TP_ATTR_USING_IPSEC, 1)) ||

  #endif

  	    (session->reorder_timeout &&

  	     nla_put_msecs(skb, L2TP_ATTR_RECV_TIMEOUT,
  			   session->reorder_timeout, L2TP_ATTR_PAD)))

  		goto nla_put_failure;

  	nest = nla_nest_start(skb, L2TP_ATTR_STATS);
  	if (nest == NULL)
  		goto nla_put_failure;

  	if (nla_put_u64_64bit(skb, L2TP_ATTR_TX_PACKETS,
  			      atomic_long_read(&session->stats.tx_packets),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_TX_BYTES,
  			      atomic_long_read(&session->stats.tx_bytes),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_TX_ERRORS,
  			      atomic_long_read(&session->stats.tx_errors),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_RX_PACKETS,
  			      atomic_long_read(&session->stats.rx_packets),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_RX_BYTES,
  			      atomic_long_read(&session->stats.rx_bytes),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_RX_SEQ_DISCARDS,
  			      atomic_long_read(&session->stats.rx_seq_discards),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_RX_OOS_PACKETS,
  			      atomic_long_read(&session->stats.rx_oos_packets),
  			      L2TP_ATTR_STATS_PAD) ||
  	    nla_put_u64_64bit(skb, L2TP_ATTR_RX_ERRORS,
  			      atomic_long_read(&session->stats.rx_errors),
  			      L2TP_ATTR_STATS_PAD))

  		goto nla_put_failure;

  	nla_nest_end(skb, nest);

  	genlmsg_end(skb, hdr);
  	return 0;

  
   nla_put_failure:
  	genlmsg_cancel(skb, hdr);
  	return -1;
  }
  
  static int l2tp_nl_cmd_session_get(struct sk_buff *skb, struct genl_info *info)
  {
  	struct l2tp_session *session;
  	struct sk_buff *msg;
  	int ret;

  	session = l2tp_nl_session_get(info, false);

  	if (session == NULL) {
  		ret = -ENODEV;

  		goto err;

  	}

  	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);

  	if (!msg) {
  		ret = -ENOMEM;

  		goto err_ref;

  	}

  	ret = l2tp_nl_session_send(msg, info->snd_portid, info->snd_seq,

  				   0, session, L2TP_CMD_SESSION_GET);

  	if (ret < 0)

  		goto err_ref_msg;

  	ret = genlmsg_unicast(genl_info_net(info), msg, info->snd_portid);

  	l2tp_session_dec_refcount(session);

  	return ret;
  
  err_ref_msg:
  	nlmsg_free(msg);
  err_ref:
  	l2tp_session_dec_refcount(session);
  err:

  	return ret;
  }
  
  static int l2tp_nl_cmd_session_dump(struct sk_buff *skb, struct netlink_callback *cb)
  {
  	struct net *net = sock_net(skb->sk);
  	struct l2tp_session *session;
  	struct l2tp_tunnel *tunnel = NULL;
  	int ti = cb->args[0];
  	int si = cb->args[1];
  
  	for (;;) {
  		if (tunnel == NULL) {
  			tunnel = l2tp_tunnel_find_nth(net, ti);
  			if (tunnel == NULL)
  				goto out;
  		}

  		session = l2tp_session_get_nth(tunnel, si, false);

  		if (session == NULL) {
  			ti++;
  			tunnel = NULL;
  			si = 0;
  			continue;
  		}

  		if (l2tp_nl_session_send(skb, NETLINK_CB(cb->skb).portid,

  					 cb->nlh->nlmsg_seq, NLM_F_MULTI,

  					 session, L2TP_CMD_SESSION_GET) < 0) {
  			l2tp_session_dec_refcount(session);

  			break;

  		}
  		l2tp_session_dec_refcount(session);

  
  		si++;
  	}
  
  out:
  	cb->args[0] = ti;
  	cb->args[1] = si;
  
  	return skb->len;
  }

  static const struct nla_policy l2tp_nl_policy[L2TP_ATTR_MAX + 1] = {

  	[L2TP_ATTR_NONE]		= { .type = NLA_UNSPEC, },
  	[L2TP_ATTR_PW_TYPE]		= { .type = NLA_U16, },
  	[L2TP_ATTR_ENCAP_TYPE]		= { .type = NLA_U16, },
  	[L2TP_ATTR_OFFSET]		= { .type = NLA_U16, },
  	[L2TP_ATTR_DATA_SEQ]		= { .type = NLA_U8, },
  	[L2TP_ATTR_L2SPEC_TYPE]		= { .type = NLA_U8, },
  	[L2TP_ATTR_L2SPEC_LEN]		= { .type = NLA_U8, },
  	[L2TP_ATTR_PROTO_VERSION]	= { .type = NLA_U8, },
  	[L2TP_ATTR_CONN_ID]		= { .type = NLA_U32, },
  	[L2TP_ATTR_PEER_CONN_ID]	= { .type = NLA_U32, },
  	[L2TP_ATTR_SESSION_ID]		= { .type = NLA_U32, },
  	[L2TP_ATTR_PEER_SESSION_ID]	= { .type = NLA_U32, },
  	[L2TP_ATTR_UDP_CSUM]		= { .type = NLA_U8, },
  	[L2TP_ATTR_VLAN_ID]		= { .type = NLA_U16, },
  	[L2TP_ATTR_DEBUG]		= { .type = NLA_U32, },
  	[L2TP_ATTR_RECV_SEQ]		= { .type = NLA_U8, },
  	[L2TP_ATTR_SEND_SEQ]		= { .type = NLA_U8, },
  	[L2TP_ATTR_LNS_MODE]		= { .type = NLA_U8, },
  	[L2TP_ATTR_USING_IPSEC]		= { .type = NLA_U8, },
  	[L2TP_ATTR_RECV_TIMEOUT]	= { .type = NLA_MSECS, },
  	[L2TP_ATTR_FD]			= { .type = NLA_U32, },
  	[L2TP_ATTR_IP_SADDR]		= { .type = NLA_U32, },
  	[L2TP_ATTR_IP_DADDR]		= { .type = NLA_U32, },
  	[L2TP_ATTR_UDP_SPORT]		= { .type = NLA_U16, },
  	[L2TP_ATTR_UDP_DPORT]		= { .type = NLA_U16, },
  	[L2TP_ATTR_MTU]			= { .type = NLA_U16, },
  	[L2TP_ATTR_MRU]			= { .type = NLA_U16, },
  	[L2TP_ATTR_STATS]		= { .type = NLA_NESTED, },

  	[L2TP_ATTR_IP6_SADDR] = {
  		.type = NLA_BINARY,
  		.len = sizeof(struct in6_addr),
  	},
  	[L2TP_ATTR_IP6_DADDR] = {
  		.type = NLA_BINARY,
  		.len = sizeof(struct in6_addr),
  	},

  	[L2TP_ATTR_IFNAME] = {
  		.type = NLA_NUL_STRING,
  		.len = IFNAMSIZ - 1,
  	},
  	[L2TP_ATTR_COOKIE] = {
  		.type = NLA_BINARY,
  		.len = 8,
  	},
  	[L2TP_ATTR_PEER_COOKIE] = {
  		.type = NLA_BINARY,
  		.len = 8,
  	},
  };

  static const struct genl_ops l2tp_nl_ops[] = {

  	{
  		.cmd = L2TP_CMD_NOOP,
  		.doit = l2tp_nl_cmd_noop,
  		.policy = l2tp_nl_policy,
  		/* can be retrieved by unprivileged users */
  	},
  	{
  		.cmd = L2TP_CMD_TUNNEL_CREATE,
  		.doit = l2tp_nl_cmd_tunnel_create,
  		.policy = l2tp_nl_policy,
  		.flags = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd = L2TP_CMD_TUNNEL_DELETE,
  		.doit = l2tp_nl_cmd_tunnel_delete,
  		.policy = l2tp_nl_policy,
  		.flags = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd = L2TP_CMD_TUNNEL_MODIFY,
  		.doit = l2tp_nl_cmd_tunnel_modify,
  		.policy = l2tp_nl_policy,
  		.flags = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd = L2TP_CMD_TUNNEL_GET,
  		.doit = l2tp_nl_cmd_tunnel_get,
  		.dumpit = l2tp_nl_cmd_tunnel_dump,
  		.policy = l2tp_nl_policy,
  		.flags = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd = L2TP_CMD_SESSION_CREATE,
  		.doit = l2tp_nl_cmd_session_create,
  		.policy = l2tp_nl_policy,
  		.flags = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd = L2TP_CMD_SESSION_DELETE,
  		.doit = l2tp_nl_cmd_session_delete,
  		.policy = l2tp_nl_policy,
  		.flags = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd = L2TP_CMD_SESSION_MODIFY,
  		.doit = l2tp_nl_cmd_session_modify,
  		.policy = l2tp_nl_policy,
  		.flags = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd = L2TP_CMD_SESSION_GET,
  		.doit = l2tp_nl_cmd_session_get,
  		.dumpit = l2tp_nl_cmd_session_dump,
  		.policy = l2tp_nl_policy,
  		.flags = GENL_ADMIN_PERM,
  	},
  };

  static struct genl_family l2tp_nl_family __ro_after_init = {

  	.name		= L2TP_GENL_NAME,
  	.version	= L2TP_GENL_VERSION,
  	.hdrsize	= 0,
  	.maxattr	= L2TP_ATTR_MAX,
  	.netnsok	= true,
  	.module		= THIS_MODULE,
  	.ops		= l2tp_nl_ops,
  	.n_ops		= ARRAY_SIZE(l2tp_nl_ops),
  	.mcgrps		= l2tp_multicast_group,
  	.n_mcgrps	= ARRAY_SIZE(l2tp_multicast_group),
  };

  int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops)
  {
  	int ret;
  
  	ret = -EINVAL;
  	if (pw_type >= __L2TP_PWTYPE_MAX)
  		goto err;
  
  	genl_lock();
  	ret = -EBUSY;
  	if (l2tp_nl_cmd_ops[pw_type])
  		goto out;
  
  	l2tp_nl_cmd_ops[pw_type] = ops;

  	ret = 0;

  
  out:
  	genl_unlock();
  err:

  	return ret;

  }
  EXPORT_SYMBOL_GPL(l2tp_nl_register_ops);
  
  void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type)
  {
  	if (pw_type < __L2TP_PWTYPE_MAX) {
  		genl_lock();
  		l2tp_nl_cmd_ops[pw_type] = NULL;
  		genl_unlock();
  	}
  }
  EXPORT_SYMBOL_GPL(l2tp_nl_unregister_ops);

  static int __init l2tp_nl_init(void)

  {

  	pr_info("L2TP netlink interface
  ");

  	return genl_register_family(&l2tp_nl_family);

  }
  
  static void l2tp_nl_cleanup(void)
  {
  	genl_unregister_family(&l2tp_nl_family);
  }
  
  module_init(l2tp_nl_init);
  module_exit(l2tp_nl_cleanup);
  
  MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
  MODULE_DESCRIPTION("L2TP netlink");
  MODULE_LICENSE("GPL");
  MODULE_VERSION("1.0");

  MODULE_ALIAS_GENL_FAMILY("l2tp");