text: // SPDX-License-Identifier: GPL-2.0
  /* Multipath TCP
   *
   * Copyright (c) 2020, Red Hat, Inc.
   */
  
  #define pr_fmt(fmt) "MPTCP: " fmt
  
  #include <linux/inet.h>
  #include <linux/kernel.h>
  #include <net/tcp.h>
  #include <net/netns/generic.h>
  #include <net/mptcp.h>
  #include <net/genetlink.h>
  #include <uapi/linux/mptcp.h>
  
  #include "protocol.h"
  #include "mib.h"
  
  /* forward declaration */
  static struct genl_family mptcp_genl_family;
  
  static int pm_nl_pernet_id;
  
  struct mptcp_pm_addr_entry {
  	struct list_head	list;
  	struct mptcp_addr_info	addr;
  	u8			flags;
  	int			ifindex;
  	struct socket		*lsk;
  };
  
  struct mptcp_pm_add_entry {
  	struct list_head	list;
  	struct mptcp_addr_info	addr;
  	struct timer_list	add_timer;
  	struct mptcp_sock	*sock;
  	u8			retrans_times;
  };
  
  struct pm_nl_pernet {
  	/* protects pernet updates */
  	spinlock_t		lock;
  	struct list_head	local_addr_list;
  	unsigned int		addrs;
  	unsigned int		stale_loss_cnt;
  	unsigned int		add_addr_signal_max;
  	unsigned int		add_addr_accept_max;
  	unsigned int		local_addr_max;
  	unsigned int		subflows_max;
  	unsigned int		next_id;
  	DECLARE_BITMAP(id_bitmap, MPTCP_PM_MAX_ADDR_ID + 1);
  };
  
  #define MPTCP_PM_ADDR_MAX	8
  #define ADD_ADDR_RETRANS_MAX	3
  
  static bool addresses_equal(const struct mptcp_addr_info *a,
  			    const struct mptcp_addr_info *b, bool use_port)
  {
  	bool addr_equals = false;
  
  	if (a->family == b->family) {
  		if (a->family == AF_INET)
  			addr_equals = a->addr.s_addr == b->addr.s_addr;
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  		else
  			addr_equals = !ipv6_addr_cmp(&a->addr6, &b->addr6);
  	} else if (a->family == AF_INET) {
  		if (ipv6_addr_v4mapped(&b->addr6))
  			addr_equals = a->addr.s_addr == b->addr6.s6_addr32[3];
  	} else if (b->family == AF_INET) {
  		if (ipv6_addr_v4mapped(&a->addr6))
  			addr_equals = a->addr6.s6_addr32[3] == b->addr.s_addr;
  #endif
  	}
  
  	if (!addr_equals)
  		return false;
  	if (!use_port)
  		return true;
  
  	return a->port == b->port;
  }
  
  static bool address_zero(const struct mptcp_addr_info *addr)
  {
  	struct mptcp_addr_info zero;
  
  	memset(&zero, 0, sizeof(zero));
  	zero.family = addr->family;
  
  	return addresses_equal(addr, &zero, true);
  }
  
  static void local_address(const struct sock_common *skc,
  			  struct mptcp_addr_info *addr)
  {
  	addr->family = skc->skc_family;
  	addr->port = htons(skc->skc_num);
  	if (addr->family == AF_INET)
  		addr->addr.s_addr = skc->skc_rcv_saddr;
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  	else if (addr->family == AF_INET6)
  		addr->addr6 = skc->skc_v6_rcv_saddr;
  #endif
  }
  
  static void remote_address(const struct sock_common *skc,
  			   struct mptcp_addr_info *addr)
  {
  	addr->family = skc->skc_family;
  	addr->port = skc->skc_dport;
  	if (addr->family == AF_INET)
  		addr->addr.s_addr = skc->skc_daddr;
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  	else if (addr->family == AF_INET6)
  		addr->addr6 = skc->skc_v6_daddr;
  #endif
  }
  
  static bool lookup_subflow_by_saddr(const struct list_head *list,
  				    struct mptcp_addr_info *saddr)
  {
  	struct mptcp_subflow_context *subflow;
  	struct mptcp_addr_info cur;
  	struct sock_common *skc;
  
  	list_for_each_entry(subflow, list, node) {
  		skc = (struct sock_common *)mptcp_subflow_tcp_sock(subflow);
  
  		local_address(skc, &cur);
  		if (addresses_equal(&cur, saddr, saddr->port))
  			return true;
  	}
  
  	return false;
  }
  
  static bool lookup_subflow_by_daddr(const struct list_head *list,
  				    struct mptcp_addr_info *daddr)
  {
  	struct mptcp_subflow_context *subflow;
  	struct mptcp_addr_info cur;
  	struct sock_common *skc;
  
  	list_for_each_entry(subflow, list, node) {
  		skc = (struct sock_common *)mptcp_subflow_tcp_sock(subflow);
  
  		remote_address(skc, &cur);
  		if (addresses_equal(&cur, daddr, daddr->port))
  			return true;
  	}
  
  	return false;
  }
  
  static struct mptcp_pm_addr_entry *
  select_local_address(const struct pm_nl_pernet *pernet,
  		     struct mptcp_sock *msk)
  {
  	struct mptcp_pm_addr_entry *entry, *ret = NULL;
  	struct sock *sk = (struct sock *)msk;
  
  	msk_owned_by_me(msk);
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
  		if (!(entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW))
  			continue;
  
  		if (!test_bit(entry->addr.id, msk->pm.id_avail_bitmap))
  			continue;
  
  		if (entry->addr.family != sk->sk_family) {
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  			if ((entry->addr.family == AF_INET &&
  			     !ipv6_addr_v4mapped(&sk->sk_v6_daddr)) ||
  			    (sk->sk_family == AF_INET &&
  			     !ipv6_addr_v4mapped(&entry->addr.addr6)))
  #endif
  				continue;
  		}
  
  		ret = entry;
  		break;
  	}
  	rcu_read_unlock();
  	return ret;
  }
  
  static struct mptcp_pm_addr_entry *
  select_signal_address(struct pm_nl_pernet *pernet, struct mptcp_sock *msk)
  {
  	struct mptcp_pm_addr_entry *entry, *ret = NULL;
  
  	rcu_read_lock();
  	/* do not keep any additional per socket state, just signal
  	 * the address list in order.
  	 * Note: removal from the local address list during the msk life-cycle
  	 * can lead to additional addresses not being announced.
  	 */
  	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
  		if (!test_bit(entry->addr.id, msk->pm.id_avail_bitmap))
  			continue;
  
  		if (!(entry->flags & MPTCP_PM_ADDR_FLAG_SIGNAL))
  			continue;
  
  		ret = entry;
  		break;
  	}
  	rcu_read_unlock();
  	return ret;
  }
  
  unsigned int mptcp_pm_get_add_addr_signal_max(struct mptcp_sock *msk)
  {
  	struct pm_nl_pernet *pernet;
  
  	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
  	return READ_ONCE(pernet->add_addr_signal_max);
  }
  EXPORT_SYMBOL_GPL(mptcp_pm_get_add_addr_signal_max);
  
  unsigned int mptcp_pm_get_add_addr_accept_max(struct mptcp_sock *msk)
  {
  	struct pm_nl_pernet *pernet;
  
  	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
  	return READ_ONCE(pernet->add_addr_accept_max);
  }
  EXPORT_SYMBOL_GPL(mptcp_pm_get_add_addr_accept_max);
  
  unsigned int mptcp_pm_get_subflows_max(struct mptcp_sock *msk)
  {
  	struct pm_nl_pernet *pernet;
  
  	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
  	return READ_ONCE(pernet->subflows_max);
  }
  EXPORT_SYMBOL_GPL(mptcp_pm_get_subflows_max);
  
  unsigned int mptcp_pm_get_local_addr_max(struct mptcp_sock *msk)
  {
  	struct pm_nl_pernet *pernet;
  
  	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
  	return READ_ONCE(pernet->local_addr_max);
  }
  EXPORT_SYMBOL_GPL(mptcp_pm_get_local_addr_max);
  
  bool mptcp_pm_nl_check_work_pending(struct mptcp_sock *msk)
  {
  	struct pm_nl_pernet *pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
  
  	if (msk->pm.subflows == mptcp_pm_get_subflows_max(msk) ||
  	    (find_next_and_bit(pernet->id_bitmap, msk->pm.id_avail_bitmap,
  			       MPTCP_PM_MAX_ADDR_ID + 1, 0) == MPTCP_PM_MAX_ADDR_ID + 1)) {
  		WRITE_ONCE(msk->pm.work_pending, false);
  		return false;
  	}
  	return true;
  }
  
  struct mptcp_pm_add_entry *
  mptcp_lookup_anno_list_by_saddr(struct mptcp_sock *msk,
  				struct mptcp_addr_info *addr)
  {
  	struct mptcp_pm_add_entry *entry;
  
  	lockdep_assert_held(&msk->pm.lock);
  
  	list_for_each_entry(entry, &msk->pm.anno_list, list) {
  		if (addresses_equal(&entry->addr, addr, true))
  			return entry;
  	}
  
  	return NULL;
  }
  
  bool mptcp_pm_sport_in_anno_list(struct mptcp_sock *msk, const struct sock *sk)
  {
  	struct mptcp_pm_add_entry *entry;
  	struct mptcp_addr_info saddr;
  	bool ret = false;
  
  	local_address((struct sock_common *)sk, &saddr);
  
  	spin_lock_bh(&msk->pm.lock);
  	list_for_each_entry(entry, &msk->pm.anno_list, list) {
  		if (addresses_equal(&entry->addr, &saddr, true)) {
  			ret = true;
  			goto out;
  		}
  	}
  
  out:
  	spin_unlock_bh(&msk->pm.lock);
  	return ret;
  }
  
  static void mptcp_pm_add_timer(struct timer_list *timer)
  {
  	struct mptcp_pm_add_entry *entry = from_timer(entry, timer, add_timer);
  	struct mptcp_sock *msk = entry->sock;
  	struct sock *sk = (struct sock *)msk;
  
  	pr_debug("msk=%p", msk);
  
  	if (!msk)
  		return;
  
  	if (inet_sk_state_load(sk) == TCP_CLOSE)
  		return;
  
  	if (!entry->addr.id)
  		return;
  
  	if (mptcp_pm_should_add_signal_addr(msk)) {
  		sk_reset_timer(sk, timer, jiffies + TCP_RTO_MAX / 8);
  		goto out;
  	}
  
  	spin_lock_bh(&msk->pm.lock);
  
  	if (!mptcp_pm_should_add_signal_addr(msk)) {
  		pr_debug("retransmit ADD_ADDR id=%d", entry->addr.id);
  		mptcp_pm_announce_addr(msk, &entry->addr, false);
  		mptcp_pm_add_addr_send_ack(msk);
  		entry->retrans_times++;
  	}
  
  	if (entry->retrans_times < ADD_ADDR_RETRANS_MAX)
  		sk_reset_timer(sk, timer,
  			       jiffies + mptcp_get_add_addr_timeout(sock_net(sk)));
  
  	spin_unlock_bh(&msk->pm.lock);
  
  	if (entry->retrans_times == ADD_ADDR_RETRANS_MAX)
  		mptcp_pm_subflow_established(msk);
  
  out:
  	__sock_put(sk);
  }
  
  struct mptcp_pm_add_entry *
  mptcp_pm_del_add_timer(struct mptcp_sock *msk,
  		       struct mptcp_addr_info *addr, bool check_id)
  {
  	struct mptcp_pm_add_entry *entry;
  	struct sock *sk = (struct sock *)msk;
  
  	spin_lock_bh(&msk->pm.lock);
  	entry = mptcp_lookup_anno_list_by_saddr(msk, addr);
  	if (entry && (!check_id || entry->addr.id == addr->id))
  		entry->retrans_times = ADD_ADDR_RETRANS_MAX;
  	spin_unlock_bh(&msk->pm.lock);
  
  	if (entry && (!check_id || entry->addr.id == addr->id))
  		sk_stop_timer_sync(sk, &entry->add_timer);
  
  	return entry;
  }
  
  static bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
  				     struct mptcp_pm_addr_entry *entry)
  {
  	struct mptcp_pm_add_entry *add_entry = NULL;
  	struct sock *sk = (struct sock *)msk;
  	struct net *net = sock_net(sk);
  
  	lockdep_assert_held(&msk->pm.lock);
  
  	if (mptcp_lookup_anno_list_by_saddr(msk, &entry->addr))
  		return false;
  
  	add_entry = kmalloc(sizeof(*add_entry), GFP_ATOMIC);
  	if (!add_entry)
  		return false;
  
  	list_add(&add_entry->list, &msk->pm.anno_list);
  
  	add_entry->addr = entry->addr;
  	add_entry->sock = msk;
  	add_entry->retrans_times = 0;
  
  	timer_setup(&add_entry->add_timer, mptcp_pm_add_timer, 0);
  	sk_reset_timer(sk, &add_entry->add_timer,
  		       jiffies + mptcp_get_add_addr_timeout(net));
  
  	return true;
  }
  
  void mptcp_pm_free_anno_list(struct mptcp_sock *msk)
  {
  	struct mptcp_pm_add_entry *entry, *tmp;
  	struct sock *sk = (struct sock *)msk;
  	LIST_HEAD(free_list);
  
  	pr_debug("msk=%p", msk);
  
  	spin_lock_bh(&msk->pm.lock);
  	list_splice_init(&msk->pm.anno_list, &free_list);
  	spin_unlock_bh(&msk->pm.lock);
  
  	list_for_each_entry_safe(entry, tmp, &free_list, list) {
  		sk_stop_timer_sync(sk, &entry->add_timer);
  		kfree(entry);
  	}
  }
  
  static bool lookup_address_in_vec(struct mptcp_addr_info *addrs, unsigned int nr,
  				  struct mptcp_addr_info *addr)
  {
  	int i;
  
  	for (i = 0; i < nr; i++) {
  		if (addresses_equal(&addrs[i], addr, addr->port))
  			return true;
  	}
  
  	return false;
  }
  
  /* Fill all the remote addresses into the array addrs[],
   * and return the array size.
   */
  static unsigned int fill_remote_addresses_vec(struct mptcp_sock *msk, bool fullmesh,
  					      struct mptcp_addr_info *addrs)
  {
  	bool deny_id0 = READ_ONCE(msk->pm.remote_deny_join_id0);
  	struct sock *sk = (struct sock *)msk, *ssk;
  	struct mptcp_subflow_context *subflow;
  	struct mptcp_addr_info remote = { 0 };
  	unsigned int subflows_max;
  	int i = 0;
  
  	subflows_max = mptcp_pm_get_subflows_max(msk);
  	remote_address((struct sock_common *)sk, &remote);
  
  	/* Non-fullmesh endpoint, fill in the single entry
  	 * corresponding to the primary MPC subflow remote address
  	 */
  	if (!fullmesh) {
  		if (deny_id0)
  			return 0;
  
  		msk->pm.subflows++;
  		addrs[i++] = remote;
  	} else {
  		mptcp_for_each_subflow(msk, subflow) {
  			ssk = mptcp_subflow_tcp_sock(subflow);
  			remote_address((struct sock_common *)ssk, &addrs[i]);
  			if (deny_id0 && addresses_equal(&addrs[i], &remote, false))
  				continue;
  
  			if (!lookup_address_in_vec(addrs, i, &addrs[i]) &&
  			    msk->pm.subflows < subflows_max) {
  				msk->pm.subflows++;
  				i++;
  			}
  		}
  	}
  
  	return i;
  }
  
  static struct mptcp_pm_addr_entry *
  __lookup_addr_by_id(struct pm_nl_pernet *pernet, unsigned int id)
  {
  	struct mptcp_pm_addr_entry *entry;
  
  	list_for_each_entry(entry, &pernet->local_addr_list, list) {
  		if (entry->addr.id == id)
  			return entry;
  	}
  	return NULL;
  }
  
  static struct mptcp_pm_addr_entry *
  __lookup_addr(struct pm_nl_pernet *pernet, const struct mptcp_addr_info *info,
  	      bool lookup_by_id)
  {
  	struct mptcp_pm_addr_entry *entry;
  
  	list_for_each_entry(entry, &pernet->local_addr_list, list) {
  		if ((!lookup_by_id && addresses_equal(&entry->addr, info, true)) ||
  		    (lookup_by_id && entry->addr.id == info->id))
  			return entry;
  	}
  	return NULL;
  }
  
  static int
  lookup_id_by_addr(struct pm_nl_pernet *pernet, const struct mptcp_addr_info *addr)
  {
  	struct mptcp_pm_addr_entry *entry;
  	int ret = -1;
  
  	rcu_read_lock();
  	list_for_each_entry(entry, &pernet->local_addr_list, list) {
  		if (addresses_equal(&entry->addr, addr, entry->addr.port)) {
  			ret = entry->addr.id;
  			break;
  		}
  	}
  	rcu_read_unlock();
  	return ret;
  }
  
  static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
  {
  	struct sock *sk = (struct sock *)msk;
  	struct mptcp_pm_addr_entry *local;
  	unsigned int add_addr_signal_max;
  	unsigned int local_addr_max;
  	struct pm_nl_pernet *pernet;
  	unsigned int subflows_max;
  
  	pernet = net_generic(sock_net(sk), pm_nl_pernet_id);
  
  	add_addr_signal_max = mptcp_pm_get_add_addr_signal_max(msk);
  	local_addr_max = mptcp_pm_get_local_addr_max(msk);
  	subflows_max = mptcp_pm_get_subflows_max(msk);
  
  	/* do lazy endpoint usage accounting for the MPC subflows */
  	if (unlikely(!(msk->pm.status & BIT(MPTCP_PM_MPC_ENDPOINT_ACCOUNTED))) && msk->first) {
  		struct mptcp_addr_info mpc_addr;
  		int mpc_id;
  
  		local_address((struct sock_common *)msk->first, &mpc_addr);
  		mpc_id = lookup_id_by_addr(pernet, &mpc_addr);
  		if (mpc_id >= 0)
  			__clear_bit(mpc_id, msk->pm.id_avail_bitmap);
  
  		msk->pm.status |= BIT(MPTCP_PM_MPC_ENDPOINT_ACCOUNTED);
  	}
  
  	pr_debug("local %d:%d signal %d:%d subflows %d:%d\n",
  		 msk->pm.local_addr_used, local_addr_max,
  		 msk->pm.add_addr_signaled, add_addr_signal_max,
  		 msk->pm.subflows, subflows_max);
  
  	/* check first for announce */
  	if (msk->pm.add_addr_signaled < add_addr_signal_max) {
  		local = select_signal_address(pernet, msk);
  
  		if (local) {
  			if (mptcp_pm_alloc_anno_list(msk, local)) {
  				__clear_bit(local->addr.id, msk->pm.id_avail_bitmap);
  				msk->pm.add_addr_signaled++;
  				mptcp_pm_announce_addr(msk, &local->addr, false);
  				mptcp_pm_nl_addr_send_ack(msk);
  			}
  		}
  	}
  
  	/* check if should create a new subflow */
  	while (msk->pm.local_addr_used < local_addr_max &&
  	       msk->pm.subflows < subflows_max) {
  		struct mptcp_addr_info addrs[MPTCP_PM_ADDR_MAX];
  		bool fullmesh;
  		int i, nr;
  
  		local = select_local_address(pernet, msk);
  		if (!local)
  			break;
  
  		fullmesh = !!(local->flags & MPTCP_PM_ADDR_FLAG_FULLMESH);
  
  		msk->pm.local_addr_used++;
  		nr = fill_remote_addresses_vec(msk, fullmesh, addrs);
  		if (nr)
  			__clear_bit(local->addr.id, msk->pm.id_avail_bitmap);
  		spin_unlock_bh(&msk->pm.lock);
  		for (i = 0; i < nr; i++)
  			__mptcp_subflow_connect(sk, &local->addr, &addrs[i]);
  		spin_lock_bh(&msk->pm.lock);
  	}
  	mptcp_pm_nl_check_work_pending(msk);
  }
  
  static void mptcp_pm_nl_fully_established(struct mptcp_sock *msk)
  {
  	mptcp_pm_create_subflow_or_signal_addr(msk);
  }
  
  static void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk)
  {
  	mptcp_pm_create_subflow_or_signal_addr(msk);
  }
  
  /* Fill all the local addresses into the array addrs[],
   * and return the array size.
   */
  static unsigned int fill_local_addresses_vec(struct mptcp_sock *msk,
  					     struct mptcp_addr_info *addrs)
  {
  	struct sock *sk = (struct sock *)msk;
  	struct mptcp_pm_addr_entry *entry;
  	struct mptcp_addr_info local;
  	struct pm_nl_pernet *pernet;
  	unsigned int subflows_max;
  	int i = 0;
  
  	pernet = net_generic(sock_net(sk), pm_nl_pernet_id);
  	subflows_max = mptcp_pm_get_subflows_max(msk);
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
  		if (!(entry->flags & MPTCP_PM_ADDR_FLAG_FULLMESH))
  			continue;
  
  		if (entry->addr.family != sk->sk_family) {
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  			if ((entry->addr.family == AF_INET &&
  			     !ipv6_addr_v4mapped(&sk->sk_v6_daddr)) ||
  			    (sk->sk_family == AF_INET &&
  			     !ipv6_addr_v4mapped(&entry->addr.addr6)))
  #endif
  				continue;
  		}
  
  		if (msk->pm.subflows < subflows_max) {
  			msk->pm.subflows++;
  			addrs[i++] = entry->addr;
  		}
  	}
  	rcu_read_unlock();
  
  	/* If the array is empty, fill in the single
  	 * 'IPADDRANY' local address
  	 */
  	if (!i) {
  		memset(&local, 0, sizeof(local));
  		local.family = msk->pm.remote.family;
  
  		msk->pm.subflows++;
  		addrs[i++] = local;
  	}
  
  	return i;
  }
  
  static void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk)
  {
  	struct mptcp_addr_info addrs[MPTCP_PM_ADDR_MAX];
  	struct sock *sk = (struct sock *)msk;
  	unsigned int add_addr_accept_max;
  	struct mptcp_addr_info remote;
  	unsigned int subflows_max;
  	int i, nr;
  
  	add_addr_accept_max = mptcp_pm_get_add_addr_accept_max(msk);
  	subflows_max = mptcp_pm_get_subflows_max(msk);
  
  	pr_debug("accepted %d:%d remote family %d",
  		 msk->pm.add_addr_accepted, add_addr_accept_max,
  		 msk->pm.remote.family);
  
  	if (lookup_subflow_by_daddr(&msk->conn_list, &msk->pm.remote))
  		goto add_addr_echo;
  
  	/* connect to the specified remote address, using whatever
  	 * local address the routing configuration will pick.
  	 */
  	remote = msk->pm.remote;
  	if (!remote.port)
  		remote.port = sk->sk_dport;
  	nr = fill_local_addresses_vec(msk, addrs);
  
  	msk->pm.add_addr_accepted++;
  	if (msk->pm.add_addr_accepted >= add_addr_accept_max ||
  	    msk->pm.subflows >= subflows_max)
  		WRITE_ONCE(msk->pm.accept_addr, false);
  
  	spin_unlock_bh(&msk->pm.lock);
  	for (i = 0; i < nr; i++)
  		__mptcp_subflow_connect(sk, &addrs[i], &remote);
  	spin_lock_bh(&msk->pm.lock);
  
  add_addr_echo:
  	mptcp_pm_announce_addr(msk, &msk->pm.remote, true);
  	mptcp_pm_nl_addr_send_ack(msk);
  }
  
  void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk)
  {
  	struct mptcp_subflow_context *subflow;
  
  	msk_owned_by_me(msk);
  	lockdep_assert_held(&msk->pm.lock);
  
  	if (!mptcp_pm_should_add_signal(msk) &&
  	    !mptcp_pm_should_rm_signal(msk))
  		return;
  
  	subflow = list_first_entry_or_null(&msk->conn_list, typeof(*subflow), node);
  	if (subflow) {
  		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
  
  		spin_unlock_bh(&msk->pm.lock);
  		pr_debug("send ack for %s",
  			 mptcp_pm_should_add_signal(msk) ? "add_addr" : "rm_addr");
  
  		mptcp_subflow_send_ack(ssk);
  		spin_lock_bh(&msk->pm.lock);
  	}
  }
  
  static int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
  					struct mptcp_addr_info *addr,
  					u8 bkup)
  {
  	struct mptcp_subflow_context *subflow;
  
  	pr_debug("bkup=%d", bkup);
  
  	mptcp_for_each_subflow(msk, subflow) {
  		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
  		struct sock *sk = (struct sock *)msk;
  		struct mptcp_addr_info local;
  
  		local_address((struct sock_common *)ssk, &local);
  		if (!addresses_equal(&local, addr, addr->port))
  			continue;
  
  		subflow->backup = bkup;
  		subflow->send_mp_prio = 1;
  		subflow->request_bkup = bkup;
  		__MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIOTX);
  
  		spin_unlock_bh(&msk->pm.lock);
  		pr_debug("send ack for mp_prio");
  		mptcp_subflow_send_ack(ssk);
  		spin_lock_bh(&msk->pm.lock);
  
  		return 0;
  	}
  
  	return -EINVAL;
  }
  
  static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk,
  					   const struct mptcp_rm_list *rm_list,
  					   enum linux_mptcp_mib_field rm_type)
  {
  	struct mptcp_subflow_context *subflow, *tmp;
  	struct sock *sk = (struct sock *)msk;
  	u8 i;
  
  	pr_debug("%s rm_list_nr %d",
  		 rm_type == MPTCP_MIB_RMADDR ? "address" : "subflow", rm_list->nr);
  
  	msk_owned_by_me(msk);
  
  	if (sk->sk_state == TCP_LISTEN)
  		return;
  
  	if (!rm_list->nr)
  		return;
  
  	if (list_empty(&msk->conn_list))
  		return;
  
  	for (i = 0; i < rm_list->nr; i++) {
  		bool removed = false;
  
  		list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
  			struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
  			int how = RCV_SHUTDOWN | SEND_SHUTDOWN;
  			u8 id = subflow->local_id;
  
  			if (rm_type == MPTCP_MIB_RMADDR)
  				id = subflow->remote_id;
  
  			if (rm_list->ids[i] != id)
  				continue;
  
  			pr_debug(" -> %s rm_list_ids[%d]=%u local_id=%u remote_id=%u",
  				 rm_type == MPTCP_MIB_RMADDR ? "address" : "subflow",
  				 i, rm_list->ids[i], subflow->local_id, subflow->remote_id);
  			spin_unlock_bh(&msk->pm.lock);
  			mptcp_subflow_shutdown(sk, ssk, how);
  
  			/* the following takes care of updating the subflows counter */
  			mptcp_close_ssk(sk, ssk, subflow);
  			spin_lock_bh(&msk->pm.lock);
  
  			removed = true;
  			__MPTCP_INC_STATS(sock_net(sk), rm_type);
  		}
  		__set_bit(rm_list->ids[i], msk->pm.id_avail_bitmap);
  		if (!removed)
  			continue;
  
  		if (rm_type == MPTCP_MIB_RMADDR) {
  			msk->pm.add_addr_accepted--;
  			WRITE_ONCE(msk->pm.accept_addr, true);
  		} else if (rm_type == MPTCP_MIB_RMSUBFLOW) {
  			msk->pm.local_addr_used--;
  		}
  	}
  }
  
  static void mptcp_pm_nl_rm_addr_received(struct mptcp_sock *msk)
  {
  	mptcp_pm_nl_rm_addr_or_subflow(msk, &msk->pm.rm_list_rx, MPTCP_MIB_RMADDR);
  }
  
  void mptcp_pm_nl_rm_subflow_received(struct mptcp_sock *msk,
  				     const struct mptcp_rm_list *rm_list)
  {
  	mptcp_pm_nl_rm_addr_or_subflow(msk, rm_list, MPTCP_MIB_RMSUBFLOW);
  }
  
  void mptcp_pm_nl_work(struct mptcp_sock *msk)
  {
  	struct mptcp_pm_data *pm = &msk->pm;
  
  	msk_owned_by_me(msk);
  
  	if (!(pm->status & MPTCP_PM_WORK_MASK))
  		return;
  
  	spin_lock_bh(&msk->pm.lock);
  
  	pr_debug("msk=%p status=%x", msk, pm->status);
  	if (pm->status & BIT(MPTCP_PM_ADD_ADDR_RECEIVED)) {
  		pm->status &= ~BIT(MPTCP_PM_ADD_ADDR_RECEIVED);
  		mptcp_pm_nl_add_addr_received(msk);
  	}
  	if (pm->status & BIT(MPTCP_PM_ADD_ADDR_SEND_ACK)) {
  		pm->status &= ~BIT(MPTCP_PM_ADD_ADDR_SEND_ACK);
  		mptcp_pm_nl_addr_send_ack(msk);
  	}
  	if (pm->status & BIT(MPTCP_PM_RM_ADDR_RECEIVED)) {
  		pm->status &= ~BIT(MPTCP_PM_RM_ADDR_RECEIVED);
  		mptcp_pm_nl_rm_addr_received(msk);
  	}
  	if (pm->status & BIT(MPTCP_PM_ESTABLISHED)) {
  		pm->status &= ~BIT(MPTCP_PM_ESTABLISHED);
  		mptcp_pm_nl_fully_established(msk);
  	}
  	if (pm->status & BIT(MPTCP_PM_SUBFLOW_ESTABLISHED)) {
  		pm->status &= ~BIT(MPTCP_PM_SUBFLOW_ESTABLISHED);
  		mptcp_pm_nl_subflow_established(msk);
  	}
  
  	spin_unlock_bh(&msk->pm.lock);
  }
  
  static bool address_use_port(struct mptcp_pm_addr_entry *entry)
  {
  	return (entry->flags &
  		(MPTCP_PM_ADDR_FLAG_SIGNAL | MPTCP_PM_ADDR_FLAG_SUBFLOW)) ==
  		MPTCP_PM_ADDR_FLAG_SIGNAL;
  }
  
  static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet,
  					     struct mptcp_pm_addr_entry *entry)
  {
  	struct mptcp_pm_addr_entry *cur;
  	unsigned int addr_max;
  	int ret = -EINVAL;
  
  	spin_lock_bh(&pernet->lock);
  	/* to keep the code simple, don't do IDR-like allocation for address ID,
  	 * just bail when we exceed limits
  	 */
  	if (pernet->next_id == MPTCP_PM_MAX_ADDR_ID)
  		pernet->next_id = 1;
  	if (pernet->addrs >= MPTCP_PM_ADDR_MAX)
  		goto out;
  	if (test_bit(entry->addr.id, pernet->id_bitmap))
  		goto out;
  
  	/* do not insert duplicate address, differentiate on port only
  	 * singled addresses
  	 */
  	list_for_each_entry(cur, &pernet->local_addr_list, list) {
  		if (addresses_equal(&cur->addr, &entry->addr,
  				    address_use_port(entry) &&
  				    address_use_port(cur)))
  			goto out;
  	}
  
  	if (!entry->addr.id) {
  find_next:
  		entry->addr.id = find_next_zero_bit(pernet->id_bitmap,
  						    MPTCP_PM_MAX_ADDR_ID + 1,
  						    pernet->next_id);
  		if (!entry->addr.id && pernet->next_id != 1) {
  			pernet->next_id = 1;
  			goto find_next;
  		}
  	}
  
  	if (!entry->addr.id)
  		goto out;
  
  	__set_bit(entry->addr.id, pernet->id_bitmap);
  	if (entry->addr.id > pernet->next_id)
  		pernet->next_id = entry->addr.id;
  
  	if (entry->flags & MPTCP_PM_ADDR_FLAG_SIGNAL) {
  		addr_max = pernet->add_addr_signal_max;
  		WRITE_ONCE(pernet->add_addr_signal_max, addr_max + 1);
  	}
  	if (entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW) {
  		addr_max = pernet->local_addr_max;
  		WRITE_ONCE(pernet->local_addr_max, addr_max + 1);
  	}
  
  	pernet->addrs++;
  	list_add_tail_rcu(&entry->list, &pernet->local_addr_list);
  	ret = entry->addr.id;
  
  out:
  	spin_unlock_bh(&pernet->lock);
  	return ret;
  }
  
  static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
  					    struct mptcp_pm_addr_entry *entry)
  {
  	int addrlen = sizeof(struct sockaddr_in);
  	struct sockaddr_storage addr;
  	struct mptcp_sock *msk;
  	struct socket *ssock;
  	int backlog = 1024;
  	int err;
  
  	err = sock_create_kern(sock_net(sk), entry->addr.family,
  			       SOCK_STREAM, IPPROTO_MPTCP, &entry->lsk);
  	if (err)
  		return err;
  
  	msk = mptcp_sk(entry->lsk->sk);
  	if (!msk) {
  		err = -EINVAL;
  		goto out;
  	}
  
  	ssock = __mptcp_nmpc_socket(msk);
  	if (!ssock) {
  		err = -EINVAL;
  		goto out;
  	}
  
  	mptcp_info2sockaddr(&entry->addr, &addr, entry->addr.family);
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  	if (entry->addr.family == AF_INET6)
  		addrlen = sizeof(struct sockaddr_in6);
  #endif
  	err = kernel_bind(ssock, (struct sockaddr *)&addr, addrlen);
  	if (err) {
  		pr_warn("kernel_bind error, err=%d", err);
  		goto out;
  	}
  
  	err = kernel_listen(ssock, backlog);
  	if (err) {
  		pr_warn("kernel_listen error, err=%d", err);
  		goto out;
  	}
  
  	return 0;
  
  out:
  	sock_release(entry->lsk);
  	return err;
  }
  
  int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
  {
  	struct mptcp_pm_addr_entry *entry;
  	struct mptcp_addr_info skc_local;
  	struct mptcp_addr_info msk_local;
  	struct pm_nl_pernet *pernet;
  	int ret = -1;
  
  	if (WARN_ON_ONCE(!msk))
  		return -1;
  
  	/* The 0 ID mapping is defined by the first subflow, copied into the msk
  	 * addr
  	 */
  	local_address((struct sock_common *)msk, &msk_local);
  	local_address((struct sock_common *)skc, &skc_local);
  	if (addresses_equal(&msk_local, &skc_local, false))
  		return 0;
  
  	if (address_zero(&skc_local))
  		return 0;
  
  	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
  		if (addresses_equal(&entry->addr, &skc_local, entry->addr.port)) {
  			ret = entry->addr.id;
  			break;
  		}
  	}
  	rcu_read_unlock();
  	if (ret >= 0)
  		return ret;
  
  	/* address not found, add to local list */
  	entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
  	if (!entry)
  		return -ENOMEM;
  
  	entry->addr = skc_local;
  	entry->addr.id = 0;
  	entry->addr.port = 0;
  	entry->ifindex = 0;
  	entry->flags = 0;
  	entry->lsk = NULL;
  	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry);
  	if (ret < 0)
  		kfree(entry);
  
  	return ret;
  }
  
  void mptcp_pm_nl_data_init(struct mptcp_sock *msk)
  {
  	struct mptcp_pm_data *pm = &msk->pm;
  	bool subflows;
  
  	subflows = !!mptcp_pm_get_subflows_max(msk);
  	WRITE_ONCE(pm->work_pending, (!!mptcp_pm_get_local_addr_max(msk) && subflows) ||
  		   !!mptcp_pm_get_add_addr_signal_max(msk));
  	WRITE_ONCE(pm->accept_addr, !!mptcp_pm_get_add_addr_accept_max(msk) && subflows);
  	WRITE_ONCE(pm->accept_subflow, subflows);
  }
  
  #define MPTCP_PM_CMD_GRP_OFFSET       0
  #define MPTCP_PM_EV_GRP_OFFSET        1
  
  static const struct genl_multicast_group mptcp_pm_mcgrps[] = {
  	[MPTCP_PM_CMD_GRP_OFFSET]	= { .name = MPTCP_PM_CMD_GRP_NAME, },
  	[MPTCP_PM_EV_GRP_OFFSET]        = { .name = MPTCP_PM_EV_GRP_NAME,
  					    .flags = GENL_UNS_ADMIN_PERM,
  					  },
  };
  
  static const struct nla_policy
  mptcp_pm_addr_policy[MPTCP_PM_ADDR_ATTR_MAX + 1] = {
  	[MPTCP_PM_ADDR_ATTR_FAMILY]	= { .type	= NLA_U16,	},
  	[MPTCP_PM_ADDR_ATTR_ID]		= { .type	= NLA_U8,	},
  	[MPTCP_PM_ADDR_ATTR_ADDR4]	= { .type	= NLA_U32,	},
  	[MPTCP_PM_ADDR_ATTR_ADDR6]	=
  		NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
  	[MPTCP_PM_ADDR_ATTR_PORT]	= { .type	= NLA_U16	},
  	[MPTCP_PM_ADDR_ATTR_FLAGS]	= { .type	= NLA_U32	},
  	[MPTCP_PM_ADDR_ATTR_IF_IDX]     = { .type	= NLA_S32	},
  };
  
  static const struct nla_policy mptcp_pm_policy[MPTCP_PM_ATTR_MAX + 1] = {
  	[MPTCP_PM_ATTR_ADDR]		=
  					NLA_POLICY_NESTED(mptcp_pm_addr_policy),
  	[MPTCP_PM_ATTR_RCV_ADD_ADDRS]	= { .type	= NLA_U32,	},
  	[MPTCP_PM_ATTR_SUBFLOWS]	= { .type	= NLA_U32,	},
  };
  
  void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
  {
  	struct mptcp_subflow_context *iter, *subflow = mptcp_subflow_ctx(ssk);
  	struct sock *sk = (struct sock *)msk;
  	unsigned int active_max_loss_cnt;
  	struct net *net = sock_net(sk);
  	unsigned int stale_loss_cnt;
  	bool slow;
  
  	stale_loss_cnt = mptcp_stale_loss_cnt(net);
  	if (subflow->stale || !stale_loss_cnt || subflow->stale_count <= stale_loss_cnt)
  		return;
  
  	/* look for another available subflow not in loss state */
  	active_max_loss_cnt = max_t(int, stale_loss_cnt - 1, 1);
  	mptcp_for_each_subflow(msk, iter) {
  		if (iter != subflow && mptcp_subflow_active(iter) &&
  		    iter->stale_count < active_max_loss_cnt) {
  			/* we have some alternatives, try to mark this subflow as idle ...*/
  			slow = lock_sock_fast(ssk);
  			if (!tcp_rtx_and_write_queues_empty(ssk)) {
  				subflow->stale = 1;
  				__mptcp_retransmit_pending_data(sk);
  				MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_SUBFLOWSTALE);
  			}
  			unlock_sock_fast(ssk, slow);
  
  			/* always try to push the pending data regarless of re-injections:
  			 * we can possibly use backup subflows now, and subflow selection
  			 * is cheap under the msk socket lock
  			 */
  			__mptcp_push_pending(sk, 0);
  			return;
  		}
  	}
  }
  
  static int mptcp_pm_family_to_addr(int family)
  {
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  	if (family == AF_INET6)
  		return MPTCP_PM_ADDR_ATTR_ADDR6;
  #endif
  	return MPTCP_PM_ADDR_ATTR_ADDR4;
  }
  
  static int mptcp_pm_parse_addr(struct nlattr *attr, struct genl_info *info,
  			       bool require_family,
  			       struct mptcp_pm_addr_entry *entry)
  {
  	struct nlattr *tb[MPTCP_PM_ADDR_ATTR_MAX + 1];
  	int err, addr_addr;
  
  	if (!attr) {
  		GENL_SET_ERR_MSG(info, "missing address info");
  		return -EINVAL;
  	}
  
  	/* no validation needed - was already done via nested policy */
  	err = nla_parse_nested_deprecated(tb, MPTCP_PM_ADDR_ATTR_MAX, attr,
  					  mptcp_pm_addr_policy, info->extack);
  	if (err)
  		return err;
  
  	memset(entry, 0, sizeof(*entry));
  	if (!tb[MPTCP_PM_ADDR_ATTR_FAMILY]) {
  		if (!require_family)
  			goto skip_family;
  
  		NL_SET_ERR_MSG_ATTR(info->extack, attr,
  				    "missing family");
  		return -EINVAL;
  	}
  
  	entry->addr.family = nla_get_u16(tb[MPTCP_PM_ADDR_ATTR_FAMILY]);
  	if (entry->addr.family != AF_INET
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  	    && entry->addr.family != AF_INET6
  #endif
  	    ) {
  		NL_SET_ERR_MSG_ATTR(info->extack, attr,
  				    "unknown address family");
  		return -EINVAL;
  	}
  	addr_addr = mptcp_pm_family_to_addr(entry->addr.family);
  	if (!tb[addr_addr]) {
  		NL_SET_ERR_MSG_ATTR(info->extack, attr,
  				    "missing address data");
  		return -EINVAL;
  	}
  
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  	if (entry->addr.family == AF_INET6)
  		entry->addr.addr6 = nla_get_in6_addr(tb[addr_addr]);
  	else
  #endif
  		entry->addr.addr.s_addr = nla_get_in_addr(tb[addr_addr]);
  
  skip_family:
  	if (tb[MPTCP_PM_ADDR_ATTR_IF_IDX]) {
  		u32 val = nla_get_s32(tb[MPTCP_PM_ADDR_ATTR_IF_IDX]);
  
  		entry->ifindex = val;
  	}
  
  	if (tb[MPTCP_PM_ADDR_ATTR_ID])
  		entry->addr.id = nla_get_u8(tb[MPTCP_PM_ADDR_ATTR_ID]);
  
  	if (tb[MPTCP_PM_ADDR_ATTR_FLAGS])
  		entry->flags = nla_get_u32(tb[MPTCP_PM_ADDR_ATTR_FLAGS]);
  
  	if (tb[MPTCP_PM_ADDR_ATTR_PORT]) {
  		if (!(entry->flags & MPTCP_PM_ADDR_FLAG_SIGNAL)) {
  			NL_SET_ERR_MSG_ATTR(info->extack, attr,
  					    "flags must have signal when using port");
  			return -EINVAL;
  		}
  		entry->addr.port = htons(nla_get_u16(tb[MPTCP_PM_ADDR_ATTR_PORT]));
  	}
  
  	return 0;
  }
  
  static struct pm_nl_pernet *genl_info_pm_nl(struct genl_info *info)
  {
  	return net_generic(genl_info_net(info), pm_nl_pernet_id);
  }
  
  static int mptcp_nl_add_subflow_or_signal_addr(struct net *net)
  {
  	struct mptcp_sock *msk;
  	long s_slot = 0, s_num = 0;
  
  	while ((msk = mptcp_token_iter_next(net, &s_slot, &s_num)) != NULL) {
  		struct sock *sk = (struct sock *)msk;
  
  		if (!READ_ONCE(msk->fully_established))
  			goto next;
  
  		lock_sock(sk);
  		spin_lock_bh(&msk->pm.lock);
  		mptcp_pm_create_subflow_or_signal_addr(msk);
  		spin_unlock_bh(&msk->pm.lock);
  		release_sock(sk);
  
  next:
  		sock_put(sk);
  		cond_resched();
  	}
  
  	return 0;
  }
  
  static int mptcp_nl_cmd_add_addr(struct sk_buff *skb, struct genl_info *info)
  {
  	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
  	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
  	struct mptcp_pm_addr_entry addr, *entry;
  	int ret;
  
  	ret = mptcp_pm_parse_addr(attr, info, true, &addr);
  	if (ret < 0)
  		return ret;
  
  	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
  	if (!entry) {
  		GENL_SET_ERR_MSG(info, "can't allocate addr");
  		return -ENOMEM;
  	}
  
  	*entry = addr;
  	if (entry->addr.port) {
  		ret = mptcp_pm_nl_create_listen_socket(skb->sk, entry);
  		if (ret) {
  			GENL_SET_ERR_MSG(info, "create listen socket error");
  			kfree(entry);
  			return ret;
  		}
  	}
  	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry);
  	if (ret < 0) {
  		GENL_SET_ERR_MSG(info, "too many addresses or duplicate one");
  		if (entry->lsk)
  			sock_release(entry->lsk);
  		kfree(entry);
  		return ret;
  	}
  
  	mptcp_nl_add_subflow_or_signal_addr(sock_net(skb->sk));
  
  	return 0;
  }
  
  int mptcp_pm_get_flags_and_ifindex_by_id(struct net *net, unsigned int id,
  					 u8 *flags, int *ifindex)
  {
  	struct mptcp_pm_addr_entry *entry;
  
  	*flags = 0;
  	*ifindex = 0;
  
  	if (id) {
  		rcu_read_lock();
  		entry = __lookup_addr_by_id(net_generic(net, pm_nl_pernet_id), id);
  		if (entry) {
  			*flags = entry->flags;
  			*ifindex = entry->ifindex;
  		}
  		rcu_read_unlock();
  	}
  
  	return 0;
  }
  
  static bool remove_anno_list_by_saddr(struct mptcp_sock *msk,
  				      struct mptcp_addr_info *addr)
  {
  	struct mptcp_pm_add_entry *entry;
  
  	entry = mptcp_pm_del_add_timer(msk, addr, false);
  	if (entry) {
  		list_del(&entry->list);
  		kfree(entry);
  		return true;
  	}
  
  	return false;
  }
  
  static bool mptcp_pm_remove_anno_addr(struct mptcp_sock *msk,
  				      struct mptcp_addr_info *addr,
  				      bool force)
  {
  	struct mptcp_rm_list list = { .nr = 0 };
  	bool ret;
  
  	list.ids[list.nr++] = addr->id;
  
  	ret = remove_anno_list_by_saddr(msk, addr);
  	if (ret || force) {
  		spin_lock_bh(&msk->pm.lock);
  		mptcp_pm_remove_addr(msk, &list);
  		spin_unlock_bh(&msk->pm.lock);
  	}
  	return ret;
  }
  
  static int mptcp_nl_remove_subflow_and_signal_addr(struct net *net,
  						   struct mptcp_addr_info *addr)
  {
  	struct mptcp_sock *msk;
  	long s_slot = 0, s_num = 0;
  	struct mptcp_rm_list list = { .nr = 0 };
  
  	pr_debug("remove_id=%d", addr->id);
  
  	list.ids[list.nr++] = addr->id;
  
  	while ((msk = mptcp_token_iter_next(net, &s_slot, &s_num)) != NULL) {
  		struct sock *sk = (struct sock *)msk;
  		bool remove_subflow;
  
  		if (list_empty(&msk->conn_list)) {
  			mptcp_pm_remove_anno_addr(msk, addr, false);
  			goto next;
  		}
  
  		lock_sock(sk);
  		remove_subflow = lookup_subflow_by_saddr(&msk->conn_list, addr);
  		mptcp_pm_remove_anno_addr(msk, addr, remove_subflow);
  		if (remove_subflow)
  			mptcp_pm_remove_subflow(msk, &list);
  		release_sock(sk);
  
  next:
  		sock_put(sk);
  		cond_resched();
  	}
  
  	return 0;
  }
  
  /* caller must ensure the RCU grace period is already elapsed */
  static void __mptcp_pm_release_addr_entry(struct mptcp_pm_addr_entry *entry)
  {
  	if (entry->lsk)
  		sock_release(entry->lsk);
  	kfree(entry);
  }
  
  static int mptcp_nl_remove_id_zero_address(struct net *net,
  					   struct mptcp_addr_info *addr)
  {
  	struct mptcp_rm_list list = { .nr = 0 };
  	long s_slot = 0, s_num = 0;
  	struct mptcp_sock *msk;
  
  	list.ids[list.nr++] = 0;
  
  	while ((msk = mptcp_token_iter_next(net, &s_slot, &s_num)) != NULL) {
  		struct sock *sk = (struct sock *)msk;
  		struct mptcp_addr_info msk_local;
  
  		if (list_empty(&msk->conn_list))
  			goto next;
  
  		local_address((struct sock_common *)msk, &msk_local);
  		if (!addresses_equal(&msk_local, addr, addr->port))
  			goto next;
  
  		lock_sock(sk);
  		spin_lock_bh(&msk->pm.lock);
  		mptcp_pm_remove_addr(msk, &list);
  		mptcp_pm_nl_rm_subflow_received(msk, &list);
  		spin_unlock_bh(&msk->pm.lock);
  		release_sock(sk);
  
  next:
  		sock_put(sk);
  		cond_resched();
  	}
  
  	return 0;
  }
  
  static int mptcp_nl_cmd_del_addr(struct sk_buff *skb, struct genl_info *info)
  {
  	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
  	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
  	struct mptcp_pm_addr_entry addr, *entry;
  	unsigned int addr_max;
  	int ret;
  
  	ret = mptcp_pm_parse_addr(attr, info, false, &addr);
  	if (ret < 0)
  		return ret;
  
  	/* the zero id address is special: the first address used by the msk
  	 * always gets such an id, so different subflows can have different zero
  	 * id addresses. Additionally zero id is not accounted for in id_bitmap.
  	 * Let's use an 'mptcp_rm_list' instead of the common remove code.
  	 */
  	if (addr.addr.id == 0)
  		return mptcp_nl_remove_id_zero_address(sock_net(skb->sk), &addr.addr);
  
  	spin_lock_bh(&pernet->lock);
  	entry = __lookup_addr_by_id(pernet, addr.addr.id);
  	if (!entry) {
  		GENL_SET_ERR_MSG(info, "address not found");
  		spin_unlock_bh(&pernet->lock);
  		return -EINVAL;
  	}
  	if (entry->flags & MPTCP_PM_ADDR_FLAG_SIGNAL) {
  		addr_max = pernet->add_addr_signal_max;
  		WRITE_ONCE(pernet->add_addr_signal_max, addr_max - 1);
  	}
  	if (entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW) {
  		addr_max = pernet->local_addr_max;
  		WRITE_ONCE(pernet->local_addr_max, addr_max - 1);
  	}
  
  	pernet->addrs--;
  	list_del_rcu(&entry->list);
  	__clear_bit(entry->addr.id, pernet->id_bitmap);
  	spin_unlock_bh(&pernet->lock);
  
  	mptcp_nl_remove_subflow_and_signal_addr(sock_net(skb->sk), &entry->addr);
  	synchronize_rcu();
  	__mptcp_pm_release_addr_entry(entry);
  
  	return ret;
  }
  
  static void mptcp_pm_remove_addrs_and_subflows(struct mptcp_sock *msk,
  					       struct list_head *rm_list)
  {
  	struct mptcp_rm_list alist = { .nr = 0 }, slist = { .nr = 0 };
  	struct mptcp_pm_addr_entry *entry;
  
  	list_for_each_entry(entry, rm_list, list) {
  		if (lookup_subflow_by_saddr(&msk->conn_list, &entry->addr) &&
  		    alist.nr < MPTCP_RM_IDS_MAX &&
  		    slist.nr < MPTCP_RM_IDS_MAX) {
  			alist.ids[alist.nr++] = entry->addr.id;
  			slist.ids[slist.nr++] = entry->addr.id;
  		} else if (remove_anno_list_by_saddr(msk, &entry->addr) &&
  			 alist.nr < MPTCP_RM_IDS_MAX) {
  			alist.ids[alist.nr++] = entry->addr.id;
  		}
  	}
  
  	if (alist.nr) {
  		spin_lock_bh(&msk->pm.lock);
  		mptcp_pm_remove_addr(msk, &alist);
  		spin_unlock_bh(&msk->pm.lock);
  	}
  	if (slist.nr)
  		mptcp_pm_remove_subflow(msk, &slist);
  }
  
  static void mptcp_nl_remove_addrs_list(struct net *net,
  				       struct list_head *rm_list)
  {
  	long s_slot = 0, s_num = 0;
  	struct mptcp_sock *msk;
  
  	if (list_empty(rm_list))
  		return;
  
  	while ((msk = mptcp_token_iter_next(net, &s_slot, &s_num)) != NULL) {
  		struct sock *sk = (struct sock *)msk;
  
  		lock_sock(sk);
  		mptcp_pm_remove_addrs_and_subflows(msk, rm_list);
  		release_sock(sk);
  
  		sock_put(sk);
  		cond_resched();
  	}
  }
  
  /* caller must ensure the RCU grace period is already elapsed */
  static void __flush_addrs(struct list_head *list)
  {
  	while (!list_empty(list)) {
  		struct mptcp_pm_addr_entry *cur;
  
  		cur = list_entry(list->next,
  				 struct mptcp_pm_addr_entry, list);
  		list_del_rcu(&cur->list);
  		__mptcp_pm_release_addr_entry(cur);
  	}
  }
  
  static void __reset_counters(struct pm_nl_pernet *pernet)
  {
  	WRITE_ONCE(pernet->add_addr_signal_max, 0);
  	WRITE_ONCE(pernet->add_addr_accept_max, 0);
  	WRITE_ONCE(pernet->local_addr_max, 0);
  	pernet->addrs = 0;
  }
  
  static int mptcp_nl_cmd_flush_addrs(struct sk_buff *skb, struct genl_info *info)
  {
  	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
  	LIST_HEAD(free_list);
  
  	spin_lock_bh(&pernet->lock);
  	list_splice_init(&pernet->local_addr_list, &free_list);
  	__reset_counters(pernet);
  	pernet->next_id = 1;
  	bitmap_zero(pernet->id_bitmap, MPTCP_PM_MAX_ADDR_ID + 1);
  	spin_unlock_bh(&pernet->lock);
  	mptcp_nl_remove_addrs_list(sock_net(skb->sk), &free_list);
  	synchronize_rcu();
  	__flush_addrs(&free_list);
  	return 0;
  }
  
  static int mptcp_nl_fill_addr(struct sk_buff *skb,
  			      struct mptcp_pm_addr_entry *entry)
  {
  	struct mptcp_addr_info *addr = &entry->addr;
  	struct nlattr *attr;
  
  	attr = nla_nest_start(skb, MPTCP_PM_ATTR_ADDR);
  	if (!attr)
  		return -EMSGSIZE;
  
  	if (nla_put_u16(skb, MPTCP_PM_ADDR_ATTR_FAMILY, addr->family))
  		goto nla_put_failure;
  	if (nla_put_u16(skb, MPTCP_PM_ADDR_ATTR_PORT, ntohs(addr->port)))
  		goto nla_put_failure;
  	if (nla_put_u8(skb, MPTCP_PM_ADDR_ATTR_ID, addr->id))
  		goto nla_put_failure;
  	if (nla_put_u32(skb, MPTCP_PM_ADDR_ATTR_FLAGS, entry->flags))
  		goto nla_put_failure;
  	if (entry->ifindex &&
  	    nla_put_s32(skb, MPTCP_PM_ADDR_ATTR_IF_IDX, entry->ifindex))
  		goto nla_put_failure;
  
  	if (addr->family == AF_INET &&
  	    nla_put_in_addr(skb, MPTCP_PM_ADDR_ATTR_ADDR4,
  			    addr->addr.s_addr))
  		goto nla_put_failure;
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  	else if (addr->family == AF_INET6 &&
  		 nla_put_in6_addr(skb, MPTCP_PM_ADDR_ATTR_ADDR6, &addr->addr6))
  		goto nla_put_failure;
  #endif
  	nla_nest_end(skb, attr);
  	return 0;
  
  nla_put_failure:
  	nla_nest_cancel(skb, attr);
  	return -EMSGSIZE;
  }
  
  static int mptcp_nl_cmd_get_addr(struct sk_buff *skb, struct genl_info *info)
  {
  	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
  	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
  	struct mptcp_pm_addr_entry addr, *entry;
  	struct sk_buff *msg;
  	void *reply;
  	int ret;
  
  	ret = mptcp_pm_parse_addr(attr, info, false, &addr);
  	if (ret < 0)
  		return ret;
  
  	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
  	if (!msg)
  		return -ENOMEM;
  
  	reply = genlmsg_put_reply(msg, info, &mptcp_genl_family, 0,
  				  info->genlhdr->cmd);
  	if (!reply) {
  		GENL_SET_ERR_MSG(info, "not enough space in Netlink message");
  		ret = -EMSGSIZE;
  		goto fail;
  	}
  
  	spin_lock_bh(&pernet->lock);
  	entry = __lookup_addr_by_id(pernet, addr.addr.id);
  	if (!entry) {
  		GENL_SET_ERR_MSG(info, "address not found");
  		ret = -EINVAL;
  		goto unlock_fail;
  	}
  
  	ret = mptcp_nl_fill_addr(msg, entry);
  	if (ret)
  		goto unlock_fail;
  
  	genlmsg_end(msg, reply);
  	ret = genlmsg_reply(msg, info);
  	spin_unlock_bh(&pernet->lock);
  	return ret;
  
  unlock_fail:
  	spin_unlock_bh(&pernet->lock);
  
  fail:
  	nlmsg_free(msg);
  	return ret;
  }
  
  static int mptcp_nl_cmd_dump_addrs(struct sk_buff *msg,
  				   struct netlink_callback *cb)
  {
  	struct net *net = sock_net(msg->sk);
  	struct mptcp_pm_addr_entry *entry;
  	struct pm_nl_pernet *pernet;
  	int id = cb->args[0];
  	void *hdr;
  	int i;
  
  	pernet = net_generic(net, pm_nl_pernet_id);
  
  	spin_lock_bh(&pernet->lock);
  	for (i = id; i < MPTCP_PM_MAX_ADDR_ID + 1; i++) {
  		if (test_bit(i, pernet->id_bitmap)) {
  			entry = __lookup_addr_by_id(pernet, i);
  			if (!entry)
  				break;
  
  			if (entry->addr.id <= id)
  				continue;
  
  			hdr = genlmsg_put(msg, NETLINK_CB(cb->skb).portid,
  					  cb->nlh->nlmsg_seq, &mptcp_genl_family,
  					  NLM_F_MULTI, MPTCP_PM_CMD_GET_ADDR);
  			if (!hdr)
  				break;
  
  			if (mptcp_nl_fill_addr(msg, entry) < 0) {
  				genlmsg_cancel(msg, hdr);
  				break;
  			}
  
  			id = entry->addr.id;
  			genlmsg_end(msg, hdr);
  		}
  	}
  	spin_unlock_bh(&pernet->lock);
  
  	cb->args[0] = id;
  	return msg->len;
  }
  
  static int parse_limit(struct genl_info *info, int id, unsigned int *limit)
  {
  	struct nlattr *attr = info->attrs[id];
  
  	if (!attr)
  		return 0;
  
  	*limit = nla_get_u32(attr);
  	if (*limit > MPTCP_PM_ADDR_MAX) {
  		GENL_SET_ERR_MSG(info, "limit greater than maximum");
  		return -EINVAL;
  	}
  	return 0;
  }
  
  static int
  mptcp_nl_cmd_set_limits(struct sk_buff *skb, struct genl_info *info)
  {
  	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
  	unsigned int rcv_addrs, subflows;
  	int ret;
  
  	spin_lock_bh(&pernet->lock);
  	rcv_addrs = pernet->add_addr_accept_max;
  	ret = parse_limit(info, MPTCP_PM_ATTR_RCV_ADD_ADDRS, &rcv_addrs);
  	if (ret)
  		goto unlock;
  
  	subflows = pernet->subflows_max;
  	ret = parse_limit(info, MPTCP_PM_ATTR_SUBFLOWS, &subflows);
  	if (ret)
  		goto unlock;
  
  	WRITE_ONCE(pernet->add_addr_accept_max, rcv_addrs);
  	WRITE_ONCE(pernet->subflows_max, subflows);
  
  unlock:
  	spin_unlock_bh(&pernet->lock);
  	return ret;
  }
  
  static int
  mptcp_nl_cmd_get_limits(struct sk_buff *skb, struct genl_info *info)
  {
  	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
  	struct sk_buff *msg;
  	void *reply;
  
  	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
  	if (!msg)
  		return -ENOMEM;
  
  	reply = genlmsg_put_reply(msg, info, &mptcp_genl_family, 0,
  				  MPTCP_PM_CMD_GET_LIMITS);
  	if (!reply)
  		goto fail;
  
  	if (nla_put_u32(msg, MPTCP_PM_ATTR_RCV_ADD_ADDRS,
  			READ_ONCE(pernet->add_addr_accept_max)))
  		goto fail;
  
  	if (nla_put_u32(msg, MPTCP_PM_ATTR_SUBFLOWS,
  			READ_ONCE(pernet->subflows_max)))
  		goto fail;
  
  	genlmsg_end(msg, reply);
  	return genlmsg_reply(msg, info);
  
  fail:
  	GENL_SET_ERR_MSG(info, "not enough space in Netlink message");
  	nlmsg_free(msg);
  	return -EMSGSIZE;
  }
  
  static int mptcp_nl_addr_backup(struct net *net,
  				struct mptcp_addr_info *addr,
  				u8 bkup)
  {
  	long s_slot = 0, s_num = 0;
  	struct mptcp_sock *msk;
  	int ret = -EINVAL;
  
  	while ((msk = mptcp_token_iter_next(net, &s_slot, &s_num)) != NULL) {
  		struct sock *sk = (struct sock *)msk;
  
  		if (list_empty(&msk->conn_list))
  			goto next;
  
  		lock_sock(sk);
  		spin_lock_bh(&msk->pm.lock);
  		ret = mptcp_pm_nl_mp_prio_send_ack(msk, addr, bkup);
  		spin_unlock_bh(&msk->pm.lock);
  		release_sock(sk);
  
  next:
  		sock_put(sk);
  		cond_resched();
  	}
  
  	return ret;
  }
  
  static int mptcp_nl_cmd_set_flags(struct sk_buff *skb, struct genl_info *info)
  {
  	struct mptcp_pm_addr_entry addr = { .addr = { .family = AF_UNSPEC }, }, *entry;
  	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
  	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
  	struct net *net = sock_net(skb->sk);
  	u8 bkup = 0, lookup_by_id = 0;
  	int ret;
  
  	ret = mptcp_pm_parse_addr(attr, info, false, &addr);
  	if (ret < 0)
  		return ret;
  
  	if (addr.flags & MPTCP_PM_ADDR_FLAG_BACKUP)
  		bkup = 1;
  	if (addr.addr.family == AF_UNSPEC) {
  		lookup_by_id = 1;
  		if (!addr.addr.id)
  			return -EOPNOTSUPP;
  	}
  
  	spin_lock_bh(&pernet->lock);
  	entry = __lookup_addr(pernet, &addr.addr, lookup_by_id);
  	if (!entry) {
  		spin_unlock_bh(&pernet->lock);
  		return -EINVAL;
  	}
  
  	if (bkup)
  		entry->flags |= MPTCP_PM_ADDR_FLAG_BACKUP;
  	else
  		entry->flags &= ~MPTCP_PM_ADDR_FLAG_BACKUP;
  	addr = *entry;
  	spin_unlock_bh(&pernet->lock);
  
  	mptcp_nl_addr_backup(net, &addr.addr, bkup);
  	return 0;
  }
  
  static void mptcp_nl_mcast_send(struct net *net, struct sk_buff *nlskb, gfp_t gfp)
  {
  	genlmsg_multicast_netns(&mptcp_genl_family, net,
  				nlskb, 0, MPTCP_PM_EV_GRP_OFFSET, gfp);
  }
  
  static int mptcp_event_add_subflow(struct sk_buff *skb, const struct sock *ssk)
  {
  	const struct inet_sock *issk = inet_sk(ssk);
  	const struct mptcp_subflow_context *sf;
  
  	if (nla_put_u16(skb, MPTCP_ATTR_FAMILY, ssk->sk_family))
  		return -EMSGSIZE;
  
  	switch (ssk->sk_family) {
  	case AF_INET:
  		if (nla_put_in_addr(skb, MPTCP_ATTR_SADDR4, issk->inet_saddr))
  			return -EMSGSIZE;
  		if (nla_put_in_addr(skb, MPTCP_ATTR_DADDR4, issk->inet_daddr))
  			return -EMSGSIZE;
  		break;
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  	case AF_INET6: {
  		const struct ipv6_pinfo *np = inet6_sk(ssk);
  
  		if (nla_put_in6_addr(skb, MPTCP_ATTR_SADDR6, &np->saddr))
  			return -EMSGSIZE;
  		if (nla_put_in6_addr(skb, MPTCP_ATTR_DADDR6, &ssk->sk_v6_daddr))
  			return -EMSGSIZE;
  		break;
  	}
  #endif
  	default:
  		WARN_ON_ONCE(1);
  		return -EMSGSIZE;
  	}
  
  	if (nla_put_be16(skb, MPTCP_ATTR_SPORT, issk->inet_sport))
  		return -EMSGSIZE;
  	if (nla_put_be16(skb, MPTCP_ATTR_DPORT, issk->inet_dport))
  		return -EMSGSIZE;
  
  	sf = mptcp_subflow_ctx(ssk);
  	if (WARN_ON_ONCE(!sf))
  		return -EINVAL;
  
  	if (nla_put_u8(skb, MPTCP_ATTR_LOC_ID, sf->local_id))
  		return -EMSGSIZE;
  
  	if (nla_put_u8(skb, MPTCP_ATTR_REM_ID, sf->remote_id))
  		return -EMSGSIZE;
  
  	return 0;
  }
  
  static int mptcp_event_put_token_and_ssk(struct sk_buff *skb,
  					 const struct mptcp_sock *msk,
  					 const struct sock *ssk)
  {
  	const struct sock *sk = (const struct sock *)msk;
  	const struct mptcp_subflow_context *sf;
  	u8 sk_err;
  
  	if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token))
  		return -EMSGSIZE;
  
  	if (mptcp_event_add_subflow(skb, ssk))
  		return -EMSGSIZE;
  
  	sf = mptcp_subflow_ctx(ssk);
  	if (WARN_ON_ONCE(!sf))
  		return -EINVAL;
  
  	if (nla_put_u8(skb, MPTCP_ATTR_BACKUP, sf->backup))
  		return -EMSGSIZE;
  
  	if (ssk->sk_bound_dev_if &&
  	    nla_put_s32(skb, MPTCP_ATTR_IF_IDX, ssk->sk_bound_dev_if))
  		return -EMSGSIZE;
  
  	sk_err = ssk->sk_err;
  	if (sk_err && sk->sk_state == TCP_ESTABLISHED &&
  	    nla_put_u8(skb, MPTCP_ATTR_ERROR, sk_err))
  		return -EMSGSIZE;
  
  	return 0;
  }
  
  static int mptcp_event_sub_established(struct sk_buff *skb,
  				       const struct mptcp_sock *msk,
  				       const struct sock *ssk)
  {
  	return mptcp_event_put_token_and_ssk(skb, msk, ssk);
  }
  
  static int mptcp_event_sub_closed(struct sk_buff *skb,
  				  const struct mptcp_sock *msk,
  				  const struct sock *ssk)
  {
  	const struct mptcp_subflow_context *sf;
  
  	if (mptcp_event_put_token_and_ssk(skb, msk, ssk))
  		return -EMSGSIZE;
  
  	sf = mptcp_subflow_ctx(ssk);
  	if (!sf->reset_seen)
  		return 0;
  
  	if (nla_put_u32(skb, MPTCP_ATTR_RESET_REASON, sf->reset_reason))
  		return -EMSGSIZE;
  
  	if (nla_put_u32(skb, MPTCP_ATTR_RESET_FLAGS, sf->reset_transient))
  		return -EMSGSIZE;
  
  	return 0;
  }
  
  static int mptcp_event_created(struct sk_buff *skb,
  			       const struct mptcp_sock *msk,
  			       const struct sock *ssk)
  {
  	int err = nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token);
  
  	if (err)
  		return err;
  
  	return mptcp_event_add_subflow(skb, ssk);
  }
  
  void mptcp_event_addr_removed(const struct mptcp_sock *msk, uint8_t id)
  {
  	struct net *net = sock_net((const struct sock *)msk);
  	struct nlmsghdr *nlh;
  	struct sk_buff *skb;
  
  	if (!genl_has_listeners(&mptcp_genl_family, net, MPTCP_PM_EV_GRP_OFFSET))
  		return;
  
  	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
  	if (!skb)
  		return;
  
  	nlh = genlmsg_put(skb, 0, 0, &mptcp_genl_family, 0, MPTCP_EVENT_REMOVED);
  	if (!nlh)
  		goto nla_put_failure;
  
  	if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token))
  		goto nla_put_failure;
  
  	if (nla_put_u8(skb, MPTCP_ATTR_REM_ID, id))
  		goto nla_put_failure;
  
  	genlmsg_end(skb, nlh);
  	mptcp_nl_mcast_send(net, skb, GFP_ATOMIC);
  	return;
  
  nla_put_failure:
  	kfree_skb(skb);
  }
  
  void mptcp_event_addr_announced(const struct mptcp_sock *msk,
  				const struct mptcp_addr_info *info)
  {
  	struct net *net = sock_net((const struct sock *)msk);
  	struct nlmsghdr *nlh;
  	struct sk_buff *skb;
  
  	if (!genl_has_listeners(&mptcp_genl_family, net, MPTCP_PM_EV_GRP_OFFSET))
  		return;
  
  	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
  	if (!skb)
  		return;
  
  	nlh = genlmsg_put(skb, 0, 0, &mptcp_genl_family, 0,
  			  MPTCP_EVENT_ANNOUNCED);
  	if (!nlh)
  		goto nla_put_failure;
  
  	if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token))
  		goto nla_put_failure;
  
  	if (nla_put_u8(skb, MPTCP_ATTR_REM_ID, info->id))
  		goto nla_put_failure;
  
  	if (nla_put_be16(skb, MPTCP_ATTR_DPORT, info->port))
  		goto nla_put_failure;
  
  	switch (info->family) {
  	case AF_INET:
  		if (nla_put_in_addr(skb, MPTCP_ATTR_DADDR4, info->addr.s_addr))
  			goto nla_put_failure;
  		break;
  #if IS_ENABLED(CONFIG_MPTCP_IPV6)
  	case AF_INET6:
  		if (nla_put_in6_addr(skb, MPTCP_ATTR_DADDR6, &info->addr6))
  			goto nla_put_failure;
  		break;
  #endif
  	default:
  		WARN_ON_ONCE(1);
  		goto nla_put_failure;
  	}
  
  	genlmsg_end(skb, nlh);
  	mptcp_nl_mcast_send(net, skb, GFP_ATOMIC);
  	return;
  
  nla_put_failure:
  	kfree_skb(skb);
  }
  
  void mptcp_event(enum mptcp_event_type type, const struct mptcp_sock *msk,
  		 const struct sock *ssk, gfp_t gfp)
  {
  	struct net *net = sock_net((const struct sock *)msk);
  	struct nlmsghdr *nlh;
  	struct sk_buff *skb;
  
  	if (!genl_has_listeners(&mptcp_genl_family, net, MPTCP_PM_EV_GRP_OFFSET))
  		return;
  
  	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, gfp);
  	if (!skb)
  		return;
  
  	nlh = genlmsg_put(skb, 0, 0, &mptcp_genl_family, 0, type);
  	if (!nlh)
  		goto nla_put_failure;
  
  	switch (type) {
  	case MPTCP_EVENT_UNSPEC:
  		WARN_ON_ONCE(1);
  		break;
  	case MPTCP_EVENT_CREATED:
  	case MPTCP_EVENT_ESTABLISHED:
  		if (mptcp_event_created(skb, msk, ssk) < 0)
  			goto nla_put_failure;
  		break;
  	case MPTCP_EVENT_CLOSED:
  		if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token) < 0)
  			goto nla_put_failure;
  		break;
  	case MPTCP_EVENT_ANNOUNCED:
  	case MPTCP_EVENT_REMOVED:
  		/* call mptcp_event_addr_announced()/removed instead */
  		WARN_ON_ONCE(1);
  		break;
  	case MPTCP_EVENT_SUB_ESTABLISHED:
  	case MPTCP_EVENT_SUB_PRIORITY:
  		if (mptcp_event_sub_established(skb, msk, ssk) < 0)
  			goto nla_put_failure;
  		break;
  	case MPTCP_EVENT_SUB_CLOSED:
  		if (mptcp_event_sub_closed(skb, msk, ssk) < 0)
  			goto nla_put_failure;
  		break;
  	}
  
  	genlmsg_end(skb, nlh);
  	mptcp_nl_mcast_send(net, skb, gfp);
  	return;
  
  nla_put_failure:
  	kfree_skb(skb);
  }
  
  static const struct genl_small_ops mptcp_pm_ops[] = {
  	{
  		.cmd    = MPTCP_PM_CMD_ADD_ADDR,
  		.doit   = mptcp_nl_cmd_add_addr,
  		.flags  = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd    = MPTCP_PM_CMD_DEL_ADDR,
  		.doit   = mptcp_nl_cmd_del_addr,
  		.flags  = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd    = MPTCP_PM_CMD_FLUSH_ADDRS,
  		.doit   = mptcp_nl_cmd_flush_addrs,
  		.flags  = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd    = MPTCP_PM_CMD_GET_ADDR,
  		.doit   = mptcp_nl_cmd_get_addr,
  		.dumpit   = mptcp_nl_cmd_dump_addrs,
  	},
  	{
  		.cmd    = MPTCP_PM_CMD_SET_LIMITS,
  		.doit   = mptcp_nl_cmd_set_limits,
  		.flags  = GENL_ADMIN_PERM,
  	},
  	{
  		.cmd    = MPTCP_PM_CMD_GET_LIMITS,
  		.doit   = mptcp_nl_cmd_get_limits,
  	},
  	{
  		.cmd    = MPTCP_PM_CMD_SET_FLAGS,
  		.doit   = mptcp_nl_cmd_set_flags,
  		.flags  = GENL_ADMIN_PERM,
  	},
  };
  
  static struct genl_family mptcp_genl_family __ro_after_init = {
  	.name		= MPTCP_PM_NAME,
  	.version	= MPTCP_PM_VER,
  	.maxattr	= MPTCP_PM_ATTR_MAX,
  	.policy		= mptcp_pm_policy,
  	.netnsok	= true,
  	.module		= THIS_MODULE,
  	.small_ops	= mptcp_pm_ops,
  	.n_small_ops	= ARRAY_SIZE(mptcp_pm_ops),
  	.mcgrps		= mptcp_pm_mcgrps,
  	.n_mcgrps	= ARRAY_SIZE(mptcp_pm_mcgrps),
  };
  
  static int __net_init pm_nl_init_net(struct net *net)
  {
  	struct pm_nl_pernet *pernet = net_generic(net, pm_nl_pernet_id);
  
  	INIT_LIST_HEAD_RCU(&pernet->local_addr_list);
  
  	/* Cit. 2 subflows ought to be enough for anybody. */
  	pernet->subflows_max = 2;
  	pernet->next_id = 1;
  	pernet->stale_loss_cnt = 4;
  	spin_lock_init(&pernet->lock);
  
  	/* No need to initialize other pernet fields, the struct is zeroed at
  	 * allocation time.
  	 */
  
  	return 0;
  }
  
  static void __net_exit pm_nl_exit_net(struct list_head *net_list)
  {
  	struct net *net;
  
  	list_for_each_entry(net, net_list, exit_list) {
  		struct pm_nl_pernet *pernet = net_generic(net, pm_nl_pernet_id);
  
  		/* net is removed from namespace list, can't race with
  		 * other modifiers, also netns core already waited for a
  		 * RCU grace period.
  		 */
  		__flush_addrs(&pernet->local_addr_list);
  	}
  }
  
  static struct pernet_operations mptcp_pm_pernet_ops = {
  	.init = pm_nl_init_net,
  	.exit_batch = pm_nl_exit_net,
  	.id = &pm_nl_pernet_id,
  	.size = sizeof(struct pm_nl_pernet),
  };
  
  void __init mptcp_pm_nl_init(void)
  {
  	if (register_pernet_subsys(&mptcp_pm_pernet_ops) < 0)
  		panic("Failed to register MPTCP PM pernet subsystem.\n");
  
  	if (genl_register_family(&mptcp_genl_family))
  		panic("Failed to register MPTCP PM netlink family\n");
  }
  