[6/7] mptcp: add netlink based PM

diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
index 3912a9808fa2..e560df80d45d 100644
--- a/include/uapi/linux/mptcp.h
+++ b/include/uapi/linux/mptcp.h
@@ -31,4 +31,55 @@  enum {
 };
 
 #define MPTCP_SUBFLOW_MAX (__MPTCP_SUBFLOW_MAX - 1)
+
+/* netlink interface */
+#define MPTCP_PM_NAME		"mptcp_pm"
+#define MPTCP_PM_CMD_GRP_NAME	"mptcp_pm_cmds"
+#define MPTCP_PM_VER		0x1
+
+/*
+ * ATTR types defined for MPTCP
+ */
+enum mptcp_pm_attrs {
+	MPTCP_PM_ATTR_UNSPEC,
+
+	MPTCP_PM_ATTR_ADDR,				/* nested address */
+	MPTCP_PM_ATTR_RCV_ADD_ADDRS,			/* u32 */
+
+	__MPTCP_PM_ATTR_MAX
+};
+
+#define MPTCP_PM_ATTR_MAX (__MPTCP_PM_ATTR_MAX - 1)
+
+enum mptcp_pm_addr_addrs {
+	MPTCP_PM_ADDR_ATTR_UNSPEC,
+
+	MPTCP_PM_ADDR_ATTR_FAMILY,			/* u16 */
+	MPTCP_PM_ADDR_ATTR_ID,				/* u8 */
+	MPTCP_PM_ADDR_ATTR_ADDR4,			/* struct in_addr */
+	MPTCP_PM_ADDR_ATTR_ADDR6,			/* struct in6_addr */
+	MPTCP_PM_ADDR_ATTR_PORT,
+	MPTCP_PM_ADDR_ATTR_FLAGS,			/* u32 */
+
+	__MPTCP_PM_ADDR_ATTR_MAX
+};
+
+#define MPTCP_PM_ADDR_ATTR_MAX (__MPTCP_PM_ADDR_ATTR_MAX - 1)
+
+#define MPTCP_PM_ADDR_FLAG_SIGNAL			(1 << 0)
+#define MPTCP_PM_ADDR_FLAG_SUBFLOW			(1 << 1)
+
+enum {
+	MPTCP_CMD_UNSPEC,
+
+	MPTCP_CMD_ADD_ADDR,
+	MPTCP_CMD_DEL_ADDR,
+	MPTCP_CMD_GET_ADDR,
+	MPTCP_CMD_FLUSH_ADDRS,
+	MPTCP_CMD_SET_RCV_ADD_ADDRS,
+	MPTCP_CMD_GET_RCV_ADD_ADDRS,
+
+	__MPTCP_CMD_AFTER_LAST
+};
+
 #endif /* _UAPI_MPTCP_H */
diff --git a/net/mptcp/Makefile b/net/mptcp/Makefile
index faebe8ec9f73..baa0640527c7 100644
--- a/net/mptcp/Makefile
+++ b/net/mptcp/Makefile
@@ -1,4 +1,5 @@ 
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_MPTCP) += mptcp.o
 
-mptcp-y := protocol.o subflow.o options.o token.o crypto.o ctrl.o pm.o diag.o mib.o
+mptcp-y := protocol.o subflow.o options.o token.o crypto.o ctrl.o pm.o diag.o \
+	   mib.o pm_netlink.o
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 033393176096..859a88559327 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -156,7 +156,7 @@  int mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 
 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
 {
-	return 0;
+	return mptcp_pm_nl_get_local_id(msk, skc);
 }
 
 static void pm_worker(struct work_struct *work)
@@ -167,6 +167,18 @@  static void pm_worker(struct work_struct *work)
 	struct sock *sk = (struct sock *)msk;
 
 	switch (pm->status) {
+	case MPTCP_PM_ADD_ADDR:
+		mptcp_pm_nl_add_addr(msk);
+		break;
+
+	case MPTCP_PM_ESTABLISHED:
+		mptcp_pm_nl_fully_established(msk);
+		break;
+
+	case MPTCP_PM_SUBFLOW_ESTABLISHED:
+		mptcp_pm_nl_subflow_established(msk);
+		break;
+
 	default:
 		break;
 	}
@@ -187,6 +199,8 @@  void mptcp_pm_data_init(struct mptcp_sock *msk)
 
 	spin_lock_init(&msk->pm.lock);
 	INIT_WORK(&msk->pm.work, pm_worker);
+
+	mptcp_pm_nl_data_init(msk);
 }
 
 void mptcp_pm_init(void)
@@ -194,4 +208,6 @@  void mptcp_pm_init(void)
 	pm_wq = alloc_workqueue("pm_wq", WQ_UNBOUND | WQ_MEM_RECLAIM, 8);
 	if (!pm_wq)
 		panic("Failed to allocate workqueue");
+
+	mptcp_pm_nl_init();
 }
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
new file mode 100644
index 000000000000..eb8c4d7ffdb0
--- /dev/null
+++ b/net/mptcp/pm_netlink.c
@@ -0,0 +1,799 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Multipath TCP
+ *
+ * Copyright (c) 2020, Red Hat, Inc.
+ */
+
+#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"
+
+/* forward declaration */
+static struct genl_family mptcp_genl_family;
+
+static int pm_nl_pernet_id;
+
+struct mptcp_pm_addr_entry {
+	struct list_head	list;
+	unsigned int		flags;
+	struct mptcp_addr_info	addr;
+	struct rcu_head		rcu;
+};
+
+struct pm_nl_pernet {
+	/* protects pernet updates */
+	spinlock_t		lock;
+	struct list_head	addr_list;
+	unsigned int		addrs;
+	unsigned int		add_addr_signal_max;
+	unsigned int		add_addr_accept_max;
+	unsigned int		local_addr_max;
+	unsigned int		next_id;
+};
+
+#define MPTCP_PM_ADDR_MAX	8
+
+static bool addresses_equal(const struct mptcp_addr_info *a,
+			    struct mptcp_addr_info *b, bool use_port)
+{
+	bool addr_equals;
+
+	if (a->family != b->family)
+		return false;
+
+	if (a->family == AF_INET)
+		addr_equals = !memcmp(&a->addr, &b->addr, sizeof(b->addr));
+	else
+		addr_equals = !memcmp(&a->addr6, &b->addr6, sizeof(b->addr6));
+
+	if (!addr_equals)
+		return false;
+	if (!use_port)
+		return true;
+
+	return a->port == b->port;
+}
+
+static void local_address(const struct sock_common *skc,
+			  struct mptcp_addr_info *addr)
+{
+	addr->family = skc->skc_family;
+	if (addr->family == AF_INET)
+		addr->addr.s_addr = skc->skc_rcv_saddr;
+#if IS_ENABLED(CONFIG_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_IPV6)
+	else if (addr->family == AF_INET6)
+		addr->addr6 = skc->skc_v6_daddr;
+#endif
+}
+
+static bool lookup_subflow_by_saddr(const struct mptcp_sock *msk,
+				    struct mptcp_addr_info *saddr)
+{
+	struct mptcp_subflow_context *subflow;
+	struct mptcp_addr_info cur;
+	struct sock_common *skc;
+
+	list_for_each_entry(subflow, &msk->conn_list, node) {
+		skc = (struct sock_common *)mptcp_subflow_tcp_sock(subflow);
+
+		local_address(skc, &cur);
+		if (addresses_equal(&cur, saddr, false))
+			return true;
+	}
+
+	return false;
+}
+
+static struct mptcp_pm_addr_entry *
+pick_local_address(const struct pm_nl_pernet *pernet,
+		   const struct mptcp_sock *msk)
+{
+	struct mptcp_pm_addr_entry *entry, *ret;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(entry, &pernet->addr_list, list) {
+		if (!(entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW))
+			continue;
+		if (entry->addr.family == ((struct sock *)msk)->sk_family &&
+		    !lookup_subflow_by_saddr(msk, &entry->addr)) {
+			ret = entry;
+			break;
+		}
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+static struct mptcp_pm_addr_entry *
+pick_signal_address(struct pm_nl_pernet *pernet, unsigned int pos)
+{
+	struct mptcp_pm_addr_entry *entry, *ret = NULL;
+	int i = 0;
+
+	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->addr_list, list) {
+		if (!(entry->flags & MPTCP_PM_ADDR_FLAG_SIGNAL))
+			continue;
+		if (++i == pos) {
+			ret = entry;
+			break;
+		}
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+static void check_work_pending(struct mptcp_sock *msk)
+{
+	if (msk->pm.local_addr_used == msk->pm.add_addr_signal_max &&
+	    msk->pm.local_addr_used == msk->pm.local_addr_max)
+		WRITE_ONCE(msk->pm.work_pending, false);
+}
+
+static void mptcp_pm_create_subflow_or_signal(struct mptcp_sock *msk)
+{
+	struct sock *sk = (struct sock *)msk;
+	struct mptcp_pm_addr_entry *local;
+	struct mptcp_addr_info remote;
+	struct pm_nl_pernet *pernet;
+
+	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
+
+	lock_sock(sk);
+
+	spin_lock_bh(&msk->pm.lock);
+
+	/* check first if should create a new subflow */
+	if (msk->pm.local_addr_used < msk->pm.local_addr_max) {
+		remote_address((struct sock_common *)sk, &remote);
+
+		local = pick_local_address(pernet, msk);
+		if (local) {
+			msk->pm.local_addr_used++;
+			check_work_pending(msk);
+			spin_unlock_bh(&msk->pm.lock);
+			__mptcp_subflow_connect(sk, &local->addr, &remote);
+			release_sock(sk);
+			return;
+		}
+
+		/* lookup failed, avoid fourther attempts later */
+		msk->pm.local_addr_used = msk->pm.local_addr_max;
+		check_work_pending(msk);
+	}
+
+	/* check for announce */
+	if (msk->pm.add_addr_signaled < msk->pm.add_addr_signal_max) {
+		local = pick_signal_address(pernet, msk->pm.add_addr_signaled);
+
+		if (local) {
+			msk->pm.local_addr_used++;
+			mptcp_pm_announce_addr(msk, &local->addr);
+		} else {
+			/* pick failed, avoid fourther attempts later */
+			msk->pm.local_addr_used = msk->pm.add_addr_signal_max;
+		}
+
+		check_work_pending(msk);
+	}
+	spin_unlock_bh(&msk->pm.lock);
+	release_sock(sk);
+}
+
+void mptcp_pm_nl_fully_established(struct mptcp_sock *msk)
+{
+	mptcp_pm_create_subflow_or_signal(msk);
+}
+
+void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk)
+{
+	mptcp_pm_create_subflow_or_signal(msk);
+}
+
+void mptcp_pm_nl_add_addr(struct mptcp_sock *msk)
+{
+	struct sock *sk = (struct sock *)msk;
+	struct mptcp_addr_info remote;
+	struct mptcp_addr_info local;
+	struct pm_nl_pernet *pernet;
+
+	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
+
+	spin_lock_bh(&msk->pm.lock);
+	if (msk->pm.add_addr_accepted >= msk->pm.add_addr_accept_max) {
+		spin_unlock_bh(&msk->pm.lock);
+		return;
+	}
+
+	/* connect to the specified remote address, using whatever
+	 * local address the routing configuration will pick.
+	 */
+	remote = msk->pm.remote;
+	memset(&local, 0, sizeof(local));
+	local.family = remote.family;
+	if (++msk->pm.add_addr_accepted == msk->pm.add_addr_accept_max)
+		WRITE_ONCE(msk->pm.accept_addr, false);
+	spin_unlock_bh(&msk->pm.lock);
+
+	lock_sock(sk);
+	__mptcp_subflow_connect((struct sock *)msk, &local, &remote);
+	release_sock(sk);
+}
+
+static int mptcp_pm_nl_append_new_addr(struct pm_nl_pernet *pernet,
+				       struct mptcp_pm_addr_entry *entry)
+{
+	struct mptcp_pm_addr_entry *cur;
+	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 > 255)
+		goto out;
+	if (pernet->addrs >= MPTCP_PM_ADDR_MAX)
+		goto out;
+
+	/* do not insert duplicate address, differentiate on port only
+	 * singled addresses
+	 */
+	list_for_each_entry(cur, &pernet->addr_list, list) {
+		if (addresses_equal(&cur->addr, &entry->addr,
+				    entry->flags == MPTCP_PM_ADDR_FLAG_SIGNAL &&
+				    cur->flags == MPTCP_PM_ADDR_FLAG_SIGNAL))
+			goto out;
+	}
+
+	if (entry->flags & MPTCP_PM_ADDR_FLAG_SIGNAL)
+		pernet->add_addr_signal_max++;
+	if (entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW)
+		pernet->local_addr_max++;
+
+	entry->addr.id = pernet->next_id++;
+	pernet->addrs++;
+	list_add_tail_rcu(&entry->list, &pernet->addr_list);
+	ret = entry->addr.id;
+
+out:
+	spin_unlock_bh(&pernet->lock);
+	return ret;
+}
+
+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 *)msk, &skc_local);
+	if (addresses_equal(&msk_local, &skc_local, false))
+		return 0;
+
+	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(entry, &pernet->addr_list, list) {
+		if (addresses_equal(&entry->addr, &skc_local, false)) {
+			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_KERNEL);
+	if (!entry)
+		return -ENOMEM;
+
+	entry->flags = 0;
+	entry->addr = skc_local;
+	ret = mptcp_pm_nl_append_new_addr(pernet, entry);
+	if (ret < 0)
+		kfree(entry);
+
+	return ret;
+}
+
+void mptcp_pm_nl_data_init(struct mptcp_sock *msk)
+{
+	struct pm_nl_pernet *pernet;
+
+	pernet = net_generic(sock_net((struct sock *)msk), pm_nl_pernet_id);
+
+	msk->pm.add_addr_signal_max = READ_ONCE(pernet->add_addr_signal_max);
+	msk->pm.add_addr_accept_max = READ_ONCE(pernet->add_addr_accept_max);
+	msk->pm.local_addr_max = READ_ONCE(pernet->local_addr_max);
+}
+
+#define MPTCP_PM_CMD_GRP_OFFSET	0
+
+static const struct genl_multicast_group mptcp_pm_mcgrps[] = {
+	[MPTCP_PM_CMD_GRP_OFFSET]	= { .name = MPTCP_PM_CMD_GRP_NAME, },
+};
+
+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]	= { .type	= NLA_EXACT_LEN,
+					    .len   = sizeof(struct in6_addr), },
+	[MPTCP_PM_ADDR_ATTR_PORT]	= { .type	= NLA_U16	},
+	[MPTCP_PM_ADDR_ATTR_FLAGS]	= { .type	= NLA_U32	},
+};
+
+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,	},
+};
+
+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) {
+		NL_SET_ERR_MSG(info->extack, "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_ID])
+		entry->addr.id = nla_get_u16(tb[MPTCP_PM_ADDR_ATTR_ID]);
+	else
+		entry->addr.id = 0;
+
+	if (tb[MPTCP_PM_ADDR_ATTR_FLAGS])
+		entry->flags = nla_get_u32(tb[MPTCP_PM_ADDR_ATTR_FLAGS]);
+	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_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)
+		return ret;
+
+	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry) {
+		NL_SET_ERR_MSG(info->extack, "can't allocate addr");
+		return -ENOMEM;
+	}
+
+	*entry = addr;
+	ret = mptcp_pm_nl_append_new_addr(pernet, entry);
+	if (ret < 0) {
+		NL_SET_ERR_MSG(info->extack, "too many addresses");
+		kfree(entry);
+		return ret;
+	}
+
+	return 0;
+}
+
+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->addr_list, list) {
+		if (entry->addr.id == id)
+			return entry;
+	}
+	return NULL;
+}
+
+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;
+	int ret;
+
+	ret = mptcp_pm_parse_addr(attr, info, false, &addr);
+	if (ret)
+		return ret;
+
+	spin_lock_bh(&pernet->lock);
+	entry = __lookup_addr_by_id(pernet, addr.addr.id);
+	if (!entry) {
+		NL_SET_ERR_MSG(info->extack, "address not found");
+		ret = -EINVAL;
+		goto out;
+	}
+	if (entry->flags & MPTCP_PM_ADDR_FLAG_SIGNAL)
+		pernet->add_addr_signal_max--;
+	if (entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW)
+		pernet->local_addr_max--;
+
+	pernet->addrs--;
+	list_del_rcu(&entry->list);
+	kfree_rcu(entry, rcu);
+out:
+	spin_unlock_bh(&pernet->lock);
+	return ret;
+}
+
+static void __flush_addrs(struct pm_nl_pernet *pernet)
+{
+	while (!list_empty(&pernet->addr_list)) {
+		struct mptcp_pm_addr_entry *cur;
+
+		cur = list_entry(pernet->addr_list.next,
+				 struct mptcp_pm_addr_entry, list);
+		list_del_rcu(&cur->list);
+		kfree_rcu(cur, rcu);
+	}
+}
+
+static void __reset_counters(struct pm_nl_pernet *pernet)
+{
+	pernet->add_addr_signal_max = 0;
+	pernet->add_addr_accept_max = 0;
+	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);
+
+	spin_lock_bh(&pernet->lock);
+	__flush_addrs(pernet);
+	__reset_counters(pernet);
+	spin_unlock_bh(&pernet->lock);
+	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_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 (addr->family == AF_INET)
+		nla_put_in_addr(skb, MPTCP_PM_ADDR_ATTR_ADDR4,
+				addr->addr.s_addr);
+#if IS_ENABLED(CONFIG_IPV6)
+	else if (addr->family == AF_INET6)
+		nla_put_in6_addr(skb, MPTCP_PM_ADDR_ATTR_ADDR6, &addr->addr6);
+#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)
+		return ret;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	reply = genlmsg_put_reply(msg, info, &mptcp_genl_family, 0,
+				  MPTCP_CMD_ADD_ADDR);
+	if (!reply) {
+		NL_SET_ERR_MSG(info->extack, "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) {
+		NL_SET_ERR_MSG(info->extack, "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;
+
+	pernet = net_generic(net, pm_nl_pernet_id);
+
+	spin_lock_bh(&pernet->lock);
+	list_for_each_entry(entry, &pernet->addr_list, list) {
+		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_CMD_ADD_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
+mptcp_nl_cmd_set_rcv_add_addrs(struct sk_buff *skb, struct genl_info *info)
+{
+	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_RCV_ADD_ADDRS];
+	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
+	int limit;
+
+	if (!attr) {
+		NL_SET_ERR_MSG(info->extack, "missing announce accept limit");
+		return -EINVAL;
+	}
+
+	limit = nla_get_u16(attr);
+	if (limit > MPTCP_PM_ADDR_MAX) {
+		NL_SET_ERR_MSG(info->extack, "announce accept limit greater than maximum");
+		return -EINVAL;
+	}
+
+	WRITE_ONCE(pernet->add_addr_accept_max, limit);
+	return 0;
+}
+
+static int
+mptcp_nl_cmd_get_rcv_add_addrs(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_CMD_GET_RCV_ADD_ADDRS);
+	if (!reply)
+		goto fail;
+
+	if (nla_put_u32(msg, MPTCP_PM_ATTR_RCV_ADD_ADDRS,
+			READ_ONCE(pernet->add_addr_accept_max)))
+		goto fail;
+
+	genlmsg_end(msg, reply);
+	return genlmsg_reply(msg, info);
+
+fail:
+	NL_SET_ERR_MSG(info->extack, "not enough space in Netlink message");
+	nlmsg_free(msg);
+	return -EMSGSIZE;
+}
+
+static struct genl_ops mptcp_pm_ops[] = {
+	{
+		.cmd    = MPTCP_CMD_ADD_ADDR,
+		.doit   = mptcp_nl_cmd_add_addr,
+		.flags  = GENL_ADMIN_PERM,
+	},
+	{
+		.cmd    = MPTCP_CMD_DEL_ADDR,
+		.doit   = mptcp_nl_cmd_del_addr,
+		.flags  = GENL_ADMIN_PERM,
+	},
+	{
+		.cmd    = MPTCP_CMD_FLUSH_ADDRS,
+		.doit   = mptcp_nl_cmd_flush_addrs,
+		.flags  = GENL_ADMIN_PERM,
+	},
+	{
+		.cmd    = MPTCP_CMD_GET_ADDR,
+		.doit   = mptcp_nl_cmd_get_addr,
+		.dumpit   = mptcp_nl_cmd_dump_addrs,
+		.flags  = GENL_ADMIN_PERM,
+	},
+	{
+		.cmd    = MPTCP_CMD_SET_RCV_ADD_ADDRS,
+		.doit   = mptcp_nl_cmd_set_rcv_add_addrs,
+		.flags  = GENL_ADMIN_PERM,
+	},
+	{
+		.cmd    = MPTCP_CMD_GET_RCV_ADD_ADDRS,
+		.doit   = mptcp_nl_cmd_get_rcv_add_addrs,
+		.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,
+	.ops		= mptcp_pm_ops,
+	.n_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->addr_list);
+	__reset_counters(pernet);
+	pernet->next_id = 1;
+	spin_lock_init(&pernet->lock);
+	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) {
+		/* net is removed from namespace list, can't race with
+		 * other modifiers
+		 */
+		__flush_addrs(net_generic(net, pm_nl_pernet_id));
+	}
+}
+
+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 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");
+}
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 9623f007f235..b8dff59cc8d1 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -386,6 +386,13 @@  int mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 			 struct mptcp_addr_info *saddr);
 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);
 
+void mptcp_pm_nl_init(void);
+void mptcp_pm_nl_data_init(struct mptcp_sock *msk);
+void mptcp_pm_nl_fully_established(struct mptcp_sock *msk);
+void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk);
+void mptcp_pm_nl_add_addr(struct mptcp_sock *msk);
+int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct sock_common *skc);
+
 static inline struct mptcp_ext *mptcp_get_ext(struct sk_buff *skb)
 {
 	return (struct mptcp_ext *)skb_ext_find(skb, SKB_EXT_MPTCP);