Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2917 insertions, 0 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
new file mode 100644
index 000000000..6857a4965
--- /dev/null
+++ b/net/netlink/af_netlink.c
@@ -0,0 +1,2917 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * NETLINK      Kernel-user communication protocol.
+ *
+ * 		Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
+ * 				Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
+ * 				Patrick McHardy <kaber@trash.net>
+ *
+ * Tue Jun 26 14:36:48 MEST 2001 Herbert "herp" Rosmanith
+ *                               added netlink_proto_exit
+ * Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo <acme@conectiva.com.br>
+ * 				 use nlk_sk, as sk->protinfo is on a diet 8)
+ * Fri Jul 22 19:51:12 MEST 2005 Harald Welte <laforge@gnumonks.org>
+ * 				 - inc module use count of module that owns
+ * 				   the kernel socket in case userspace opens
+ * 				   socket of same protocol
+ * 				 - remove all module support, since netlink is
+ * 				   mandatory if CONFIG_NET=y these days
+ */
+
+#include <linux/module.h>
+
+#include <linux/bpf.h>
+#include <linux/capability.h>
+#include <linux/kernel.h>
+#include <linux/filter.h>
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/stat.h>
+#include <linux/socket.h>
+#include <linux/un.h>
+#include <linux/fcntl.h>
+#include <linux/termios.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/notifier.h>
+#include <linux/security.h>
+#include <linux/jhash.h>
+#include <linux/jiffies.h>
+#include <linux/random.h>
+#include <linux/bitops.h>
+#include <linux/mm.h>
+#include <linux/types.h>
+#include <linux/audit.h>
+#include <linux/mutex.h>
+#include <linux/vmalloc.h>
+#include <linux/if_arp.h>
+#include <linux/rhashtable.h>
+#include <asm/cacheflush.h>
+#include <linux/hash.h>
+#include <linux/genetlink.h>
+#include <linux/net_namespace.h>
+#include <linux/nospec.h>
+#include <linux/btf_ids.h>
+
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <net/sock.h>
+#include <net/scm.h>
+#include <net/netlink.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/netlink.h>
+
+#include "af_netlink.h"
+
+struct listeners {
+	struct rcu_head		rcu;
+	unsigned long		masks[];
+};
+
+/* state bits */
+#define NETLINK_S_CONGESTED		0x0
+
+static inline int netlink_is_kernel(struct sock *sk)
+{
+	return nlk_test_bit(KERNEL_SOCKET, sk);
+}
+
+struct netlink_table *nl_table __read_mostly;
+EXPORT_SYMBOL_GPL(nl_table);
+
+static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
+
+static struct lock_class_key nlk_cb_mutex_keys[MAX_LINKS];
+
+static const char *const nlk_cb_mutex_key_strings[MAX_LINKS + 1] = {
+	"nlk_cb_mutex-ROUTE",
+	"nlk_cb_mutex-1",
+	"nlk_cb_mutex-USERSOCK",
+	"nlk_cb_mutex-FIREWALL",
+	"nlk_cb_mutex-SOCK_DIAG",
+	"nlk_cb_mutex-NFLOG",
+	"nlk_cb_mutex-XFRM",
+	"nlk_cb_mutex-SELINUX",
+	"nlk_cb_mutex-ISCSI",
+	"nlk_cb_mutex-AUDIT",
+	"nlk_cb_mutex-FIB_LOOKUP",
+	"nlk_cb_mutex-CONNECTOR",
+	"nlk_cb_mutex-NETFILTER",
+	"nlk_cb_mutex-IP6_FW",
+	"nlk_cb_mutex-DNRTMSG",
+	"nlk_cb_mutex-KOBJECT_UEVENT",
+	"nlk_cb_mutex-GENERIC",
+	"nlk_cb_mutex-17",
+	"nlk_cb_mutex-SCSITRANSPORT",
+	"nlk_cb_mutex-ECRYPTFS",
+	"nlk_cb_mutex-RDMA",
+	"nlk_cb_mutex-CRYPTO",
+	"nlk_cb_mutex-SMC",
+	"nlk_cb_mutex-23",
+	"nlk_cb_mutex-24",
+	"nlk_cb_mutex-25",
+	"nlk_cb_mutex-26",
+	"nlk_cb_mutex-27",
+	"nlk_cb_mutex-28",
+	"nlk_cb_mutex-29",
+	"nlk_cb_mutex-30",
+	"nlk_cb_mutex-31",
+	"nlk_cb_mutex-MAX_LINKS"
+};
+
+static int netlink_dump(struct sock *sk);
+
+/* nl_table locking explained:
+ * Lookup and traversal are protected with an RCU read-side lock. Insertion
+ * and removal are protected with per bucket lock while using RCU list
+ * modification primitives and may run in parallel to RCU protected lookups.
+ * Destruction of the Netlink socket may only occur *after* nl_table_lock has
+ * been acquired * either during or after the socket has been removed from
+ * the list and after an RCU grace period.
+ */
+DEFINE_RWLOCK(nl_table_lock);
+EXPORT_SYMBOL_GPL(nl_table_lock);
+static atomic_t nl_table_users = ATOMIC_INIT(0);
+
+#define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
+
+static BLOCKING_NOTIFIER_HEAD(netlink_chain);
+
+
+static const struct rhashtable_params netlink_rhashtable_params;
+
+void do_trace_netlink_extack(const char *msg)
+{
+	trace_netlink_extack(msg);
+}
+EXPORT_SYMBOL(do_trace_netlink_extack);
+
+static inline u32 netlink_group_mask(u32 group)
+{
+	if (group > 32)
+		return 0;
+	return group ? 1 << (group - 1) : 0;
+}
+
+static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
+					   gfp_t gfp_mask)
+{
+	unsigned int len = skb_end_offset(skb);
+	struct sk_buff *new;
+
+	new = alloc_skb(len, gfp_mask);
+	if (new == NULL)
+		return NULL;
+
+	NETLINK_CB(new).portid = NETLINK_CB(skb).portid;
+	NETLINK_CB(new).dst_group = NETLINK_CB(skb).dst_group;
+	NETLINK_CB(new).creds = NETLINK_CB(skb).creds;
+
+	skb_put_data(new, skb->data, len);
+	return new;
+}
+
+static unsigned int netlink_tap_net_id;
+
+struct netlink_tap_net {
+	struct list_head netlink_tap_all;
+	struct mutex netlink_tap_lock;
+};
+
+int netlink_add_tap(struct netlink_tap *nt)
+{
+	struct net *net = dev_net(nt->dev);
+	struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
+
+	if (unlikely(nt->dev->type != ARPHRD_NETLINK))
+		return -EINVAL;
+
+	mutex_lock(&nn->netlink_tap_lock);
+	list_add_rcu(&nt->list, &nn->netlink_tap_all);
+	mutex_unlock(&nn->netlink_tap_lock);
+
+	__module_get(nt->module);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(netlink_add_tap);
+
+static int __netlink_remove_tap(struct netlink_tap *nt)
+{
+	struct net *net = dev_net(nt->dev);
+	struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
+	bool found = false;
+	struct netlink_tap *tmp;
+
+	mutex_lock(&nn->netlink_tap_lock);
+
+	list_for_each_entry(tmp, &nn->netlink_tap_all, list) {
+		if (nt == tmp) {
+			list_del_rcu(&nt->list);
+			found = true;
+			goto out;
+		}
+	}
+
+	pr_warn("__netlink_remove_tap: %p not found\n", nt);
+out:
+	mutex_unlock(&nn->netlink_tap_lock);
+
+	if (found)
+		module_put(nt->module);
+
+	return found ? 0 : -ENODEV;
+}
+
+int netlink_remove_tap(struct netlink_tap *nt)
+{
+	int ret;
+
+	ret = __netlink_remove_tap(nt);
+	synchronize_net();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(netlink_remove_tap);
+
+static __net_init int netlink_tap_init_net(struct net *net)
+{
+	struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
+
+	INIT_LIST_HEAD(&nn->netlink_tap_all);
+	mutex_init(&nn->netlink_tap_lock);
+	return 0;
+}
+
+static struct pernet_operations netlink_tap_net_ops = {
+	.init = netlink_tap_init_net,
+	.id   = &netlink_tap_net_id,
+	.size = sizeof(struct netlink_tap_net),
+};
+
+static bool netlink_filter_tap(const struct sk_buff *skb)
+{
+	struct sock *sk = skb->sk;
+
+	/* We take the more conservative approach and
+	 * whitelist socket protocols that may pass.
+	 */
+	switch (sk->sk_protocol) {
+	case NETLINK_ROUTE:
+	case NETLINK_USERSOCK:
+	case NETLINK_SOCK_DIAG:
+	case NETLINK_NFLOG:
+	case NETLINK_XFRM:
+	case NETLINK_FIB_LOOKUP:
+	case NETLINK_NETFILTER:
+	case NETLINK_GENERIC:
+		return true;
+	}
+
+	return false;
+}
+
+static int __netlink_deliver_tap_skb(struct sk_buff *skb,
+				     struct net_device *dev)
+{
+	struct sk_buff *nskb;
+	struct sock *sk = skb->sk;
+	int ret = -ENOMEM;
+
+	if (!net_eq(dev_net(dev), sock_net(sk)))
+		return 0;
+
+	dev_hold(dev);
+
+	if (is_vmalloc_addr(skb->head))
+		nskb = netlink_to_full_skb(skb, GFP_ATOMIC);
+	else
+		nskb = skb_clone(skb, GFP_ATOMIC);
+	if (nskb) {
+		nskb->dev = dev;
+		nskb->protocol = htons((u16) sk->sk_protocol);
+		nskb->pkt_type = netlink_is_kernel(sk) ?
+				 PACKET_KERNEL : PACKET_USER;
+		skb_reset_network_header(nskb);
+		ret = dev_queue_xmit(nskb);
+		if (unlikely(ret > 0))
+			ret = net_xmit_errno(ret);
+	}
+
+	dev_put(dev);
+	return ret;
+}
+
+static void __netlink_deliver_tap(struct sk_buff *skb, struct netlink_tap_net *nn)
+{
+	int ret;
+	struct netlink_tap *tmp;
+
+	if (!netlink_filter_tap(skb))
+		return;
+
+	list_for_each_entry_rcu(tmp, &nn->netlink_tap_all, list) {
+		ret = __netlink_deliver_tap_skb(skb, tmp->dev);
+		if (unlikely(ret))
+			break;
+	}
+}
+
+static void netlink_deliver_tap(struct net *net, struct sk_buff *skb)
+{
+	struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
+
+	rcu_read_lock();
+
+	if (unlikely(!list_empty(&nn->netlink_tap_all)))
+		__netlink_deliver_tap(skb, nn);
+
+	rcu_read_unlock();
+}
+
+static void netlink_deliver_tap_kernel(struct sock *dst, struct sock *src,
+				       struct sk_buff *skb)
+{
+	if (!(netlink_is_kernel(dst) && netlink_is_kernel(src)))
+		netlink_deliver_tap(sock_net(dst), skb);
+}
+
+static void netlink_overrun(struct sock *sk)
+{
+	if (!nlk_test_bit(RECV_NO_ENOBUFS, sk)) {
+		if (!test_and_set_bit(NETLINK_S_CONGESTED,
+				      &nlk_sk(sk)->state)) {
+			WRITE_ONCE(sk->sk_err, ENOBUFS);
+			sk_error_report(sk);
+		}
+	}
+	atomic_inc(&sk->sk_drops);
+}
+
+static void netlink_rcv_wake(struct sock *sk)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+
+	if (skb_queue_empty_lockless(&sk->sk_receive_queue))
+		clear_bit(NETLINK_S_CONGESTED, &nlk->state);
+	if (!test_bit(NETLINK_S_CONGESTED, &nlk->state))
+		wake_up_interruptible(&nlk->wait);
+}
+
+static void netlink_skb_destructor(struct sk_buff *skb)
+{
+	if (is_vmalloc_addr(skb->head)) {
+		if (!skb->cloned ||
+		    !atomic_dec_return(&(skb_shinfo(skb)->dataref)))
+			vfree_atomic(skb->head);
+
+		skb->head = NULL;
+	}
+	if (skb->sk != NULL)
+		sock_rfree(skb);
+}
+
+static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
+{
+	WARN_ON(skb->sk != NULL);
+	skb->sk = sk;
+	skb->destructor = netlink_skb_destructor;
+	atomic_add(skb->truesize, &sk->sk_rmem_alloc);
+	sk_mem_charge(sk, skb->truesize);
+}
+
+static void netlink_sock_destruct(struct sock *sk)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+
+	if (nlk->cb_running) {
+		if (nlk->cb.done)
+			nlk->cb.done(&nlk->cb);
+		module_put(nlk->cb.module);
+		kfree_skb(nlk->cb.skb);
+	}
+
+	skb_queue_purge(&sk->sk_receive_queue);
+
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
+		return;
+	}
+
+	WARN_ON(atomic_read(&sk->sk_rmem_alloc));
+	WARN_ON(refcount_read(&sk->sk_wmem_alloc));
+	WARN_ON(nlk_sk(sk)->groups);
+}
+
+static void netlink_sock_destruct_work(struct work_struct *work)
+{
+	struct netlink_sock *nlk = container_of(work, struct netlink_sock,
+						work);
+
+	sk_free(&nlk->sk);
+}
+
+/* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
+ * SMP. Look, when several writers sleep and reader wakes them up, all but one
+ * immediately hit write lock and grab all the cpus. Exclusive sleep solves
+ * this, _but_ remember, it adds useless work on UP machines.
+ */
+
+void netlink_table_grab(void)
+	__acquires(nl_table_lock)
+{
+	might_sleep();
+
+	write_lock_irq(&nl_table_lock);
+
+	if (atomic_read(&nl_table_users)) {
+		DECLARE_WAITQUEUE(wait, current);
+
+		add_wait_queue_exclusive(&nl_table_wait, &wait);
+		for (;;) {
+			set_current_state(TASK_UNINTERRUPTIBLE);
+			if (atomic_read(&nl_table_users) == 0)
+				break;
+			write_unlock_irq(&nl_table_lock);
+			schedule();
+			write_lock_irq(&nl_table_lock);
+		}
+
+		__set_current_state(TASK_RUNNING);
+		remove_wait_queue(&nl_table_wait, &wait);
+	}
+}
+
+void netlink_table_ungrab(void)
+	__releases(nl_table_lock)
+{
+	write_unlock_irq(&nl_table_lock);
+	wake_up(&nl_table_wait);
+}
+
+static inline void
+netlink_lock_table(void)
+{
+	unsigned long flags;
+
+	/* read_lock() synchronizes us to netlink_table_grab */
+
+	read_lock_irqsave(&nl_table_lock, flags);
+	atomic_inc(&nl_table_users);
+	read_unlock_irqrestore(&nl_table_lock, flags);
+}
+
+static inline void
+netlink_unlock_table(void)
+{
+	if (atomic_dec_and_test(&nl_table_users))
+		wake_up(&nl_table_wait);
+}
+
+struct netlink_compare_arg
+{
+	possible_net_t pnet;
+	u32 portid;
+};
+
+/* Doing sizeof directly may yield 4 extra bytes on 64-bit. */
+#define netlink_compare_arg_len \
+	(offsetof(struct netlink_compare_arg, portid) + sizeof(u32))
+
+static inline int netlink_compare(struct rhashtable_compare_arg *arg,
+				  const void *ptr)
+{
+	const struct netlink_compare_arg *x = arg->key;
+	const struct netlink_sock *nlk = ptr;
+
+	return nlk->portid != x->portid ||
+	       !net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet));
+}
+
+static void netlink_compare_arg_init(struct netlink_compare_arg *arg,
+				     struct net *net, u32 portid)
+{
+	memset(arg, 0, sizeof(*arg));
+	write_pnet(&arg->pnet, net);
+	arg->portid = portid;
+}
+
+static struct sock *__netlink_lookup(struct netlink_table *table, u32 portid,
+				     struct net *net)
+{
+	struct netlink_compare_arg arg;
+
+	netlink_compare_arg_init(&arg, net, portid);
+	return rhashtable_lookup_fast(&table->hash, &arg,
+				      netlink_rhashtable_params);
+}
+
+static int __netlink_insert(struct netlink_table *table, struct sock *sk)
+{
+	struct netlink_compare_arg arg;
+
+	netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid);
+	return rhashtable_lookup_insert_key(&table->hash, &arg,
+					    &nlk_sk(sk)->node,
+					    netlink_rhashtable_params);
+}
+
+static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
+{
+	struct netlink_table *table = &nl_table[protocol];
+	struct sock *sk;
+
+	rcu_read_lock();
+	sk = __netlink_lookup(table, portid, net);
+	if (sk)
+		sock_hold(sk);
+	rcu_read_unlock();
+
+	return sk;
+}
+
+static const struct proto_ops netlink_ops;
+
+static void
+netlink_update_listeners(struct sock *sk)
+{
+	struct netlink_table *tbl = &nl_table[sk->sk_protocol];
+	unsigned long mask;
+	unsigned int i;
+	struct listeners *listeners;
+
+	listeners = nl_deref_protected(tbl->listeners);
+	if (!listeners)
+		return;
+
+	for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
+		mask = 0;
+		sk_for_each_bound(sk, &tbl->mc_list) {
+			if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
+				mask |= nlk_sk(sk)->groups[i];
+		}
+		listeners->masks[i] = mask;
+	}
+	/* this function is only called with the netlink table "grabbed", which
+	 * makes sure updates are visible before bind or setsockopt return. */
+}
+
+static int netlink_insert(struct sock *sk, u32 portid)
+{
+	struct netlink_table *table = &nl_table[sk->sk_protocol];
+	int err;
+
+	lock_sock(sk);
+
+	err = nlk_sk(sk)->portid == portid ? 0 : -EBUSY;
+	if (nlk_sk(sk)->bound)
+		goto err;
+
+	/* portid can be read locklessly from netlink_getname(). */
+	WRITE_ONCE(nlk_sk(sk)->portid, portid);
+
+	sock_hold(sk);
+
+	err = __netlink_insert(table, sk);
+	if (err) {
+		/* In case the hashtable backend returns with -EBUSY
+		 * from here, it must not escape to the caller.
+		 */
+		if (unlikely(err == -EBUSY))
+			err = -EOVERFLOW;
+		if (err == -EEXIST)
+			err = -EADDRINUSE;
+		sock_put(sk);
+		goto err;
+	}
+
+	/* We need to ensure that the socket is hashed and visible. */
+	smp_wmb();
+	/* Paired with lockless reads from netlink_bind(),
+	 * netlink_connect() and netlink_sendmsg().
+	 */
+	WRITE_ONCE(nlk_sk(sk)->bound, portid);
+
+err:
+	release_sock(sk);
+	return err;
+}
+
+static void netlink_remove(struct sock *sk)
+{
+	struct netlink_table *table;
+
+	table = &nl_table[sk->sk_protocol];
+	if (!rhashtable_remove_fast(&table->hash, &nlk_sk(sk)->node,
+				    netlink_rhashtable_params)) {
+		WARN_ON(refcount_read(&sk->sk_refcnt) == 1);
+		__sock_put(sk);
+	}
+
+	netlink_table_grab();
+	if (nlk_sk(sk)->subscriptions) {
+		__sk_del_bind_node(sk);
+		netlink_update_listeners(sk);
+	}
+	if (sk->sk_protocol == NETLINK_GENERIC)
+		atomic_inc(&genl_sk_destructing_cnt);
+	netlink_table_ungrab();
+}
+
+static struct proto netlink_proto = {
+	.name	  = "NETLINK",
+	.owner	  = THIS_MODULE,
+	.obj_size = sizeof(struct netlink_sock),
+};
+
+static int __netlink_create(struct net *net, struct socket *sock,
+			    struct mutex *cb_mutex, int protocol,
+			    int kern)
+{
+	struct sock *sk;
+	struct netlink_sock *nlk;
+
+	sock->ops = &netlink_ops;
+
+	sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto, kern);
+	if (!sk)
+		return -ENOMEM;
+
+	sock_init_data(sock, sk);
+
+	nlk = nlk_sk(sk);
+	if (cb_mutex) {
+		nlk->cb_mutex = cb_mutex;
+	} else {
+		nlk->cb_mutex = &nlk->cb_def_mutex;
+		mutex_init(nlk->cb_mutex);
+		lockdep_set_class_and_name(nlk->cb_mutex,
+					   nlk_cb_mutex_keys + protocol,
+					   nlk_cb_mutex_key_strings[protocol]);
+	}
+	init_waitqueue_head(&nlk->wait);
+
+	sk->sk_destruct = netlink_sock_destruct;
+	sk->sk_protocol = protocol;
+	return 0;
+}
+
+static int netlink_create(struct net *net, struct socket *sock, int protocol,
+			  int kern)
+{
+	struct module *module = NULL;
+	struct mutex *cb_mutex;
+	struct netlink_sock *nlk;
+	int (*bind)(struct net *net, int group);
+	void (*unbind)(struct net *net, int group);
+	int err = 0;
+
+	sock->state = SS_UNCONNECTED;
+
+	if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
+		return -ESOCKTNOSUPPORT;
+
+	if (protocol < 0 || protocol >= MAX_LINKS)
+		return -EPROTONOSUPPORT;
+	protocol = array_index_nospec(protocol, MAX_LINKS);
+
+	netlink_lock_table();
+#ifdef CONFIG_MODULES
+	if (!nl_table[protocol].registered) {
+		netlink_unlock_table();
+		request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
+		netlink_lock_table();
+	}
+#endif
+	if (nl_table[protocol].registered &&
+	    try_module_get(nl_table[protocol].module))
+		module = nl_table[protocol].module;
+	else
+		err = -EPROTONOSUPPORT;
+	cb_mutex = nl_table[protocol].cb_mutex;
+	bind = nl_table[protocol].bind;
+	unbind = nl_table[protocol].unbind;
+	netlink_unlock_table();
+
+	if (err < 0)
+		goto out;
+
+	err = __netlink_create(net, sock, cb_mutex, protocol, kern);
+	if (err < 0)
+		goto out_module;
+
+	sock_prot_inuse_add(net, &netlink_proto, 1);
+
+	nlk = nlk_sk(sock->sk);
+	nlk->module = module;
+	nlk->netlink_bind = bind;
+	nlk->netlink_unbind = unbind;
+out:
+	return err;
+
+out_module:
+	module_put(module);
+	goto out;
+}
+
+static void deferred_put_nlk_sk(struct rcu_head *head)
+{
+	struct netlink_sock *nlk = container_of(head, struct netlink_sock, rcu);
+	struct sock *sk = &nlk->sk;
+
+	kfree(nlk->groups);
+	nlk->groups = NULL;
+
+	if (!refcount_dec_and_test(&sk->sk_refcnt))
+		return;
+
+	if (nlk->cb_running && nlk->cb.done) {
+		INIT_WORK(&nlk->work, netlink_sock_destruct_work);
+		schedule_work(&nlk->work);
+		return;
+	}
+
+	sk_free(sk);
+}
+
+static int netlink_release(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct netlink_sock *nlk;
+
+	if (!sk)
+		return 0;
+
+	netlink_remove(sk);
+	sock_orphan(sk);
+	nlk = nlk_sk(sk);
+
+	/*
+	 * OK. Socket is unlinked, any packets that arrive now
+	 * will be purged.
+	 */
+
+	/* must not acquire netlink_table_lock in any way again before unbind
+	 * and notifying genetlink is done as otherwise it might deadlock
+	 */
+	if (nlk->netlink_unbind) {
+		int i;
+
+		for (i = 0; i < nlk->ngroups; i++)
+			if (test_bit(i, nlk->groups))
+				nlk->netlink_unbind(sock_net(sk), i + 1);
+	}
+	if (sk->sk_protocol == NETLINK_GENERIC &&
+	    atomic_dec_return(&genl_sk_destructing_cnt) == 0)
+		wake_up(&genl_sk_destructing_waitq);
+
+	sock->sk = NULL;
+	wake_up_interruptible_all(&nlk->wait);
+
+	skb_queue_purge(&sk->sk_write_queue);
+
+	if (nlk->portid && nlk->bound) {
+		struct netlink_notify n = {
+						.net = sock_net(sk),
+						.protocol = sk->sk_protocol,
+						.portid = nlk->portid,
+					  };
+		blocking_notifier_call_chain(&netlink_chain,
+				NETLINK_URELEASE, &n);
+	}
+
+	module_put(nlk->module);
+
+	if (netlink_is_kernel(sk)) {
+		netlink_table_grab();
+		BUG_ON(nl_table[sk->sk_protocol].registered == 0);
+		if (--nl_table[sk->sk_protocol].registered == 0) {
+			struct listeners *old;
+
+			old = nl_deref_protected(nl_table[sk->sk_protocol].listeners);
+			RCU_INIT_POINTER(nl_table[sk->sk_protocol].listeners, NULL);
+			kfree_rcu(old, rcu);
+			nl_table[sk->sk_protocol].module = NULL;
+			nl_table[sk->sk_protocol].bind = NULL;
+			nl_table[sk->sk_protocol].unbind = NULL;
+			nl_table[sk->sk_protocol].flags = 0;
+			nl_table[sk->sk_protocol].registered = 0;
+		}
+		netlink_table_ungrab();
+	}
+
+	sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
+	call_rcu(&nlk->rcu, deferred_put_nlk_sk);
+	return 0;
+}
+
+static int netlink_autobind(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct net *net = sock_net(sk);
+	struct netlink_table *table = &nl_table[sk->sk_protocol];
+	s32 portid = task_tgid_vnr(current);
+	int err;
+	s32 rover = -4096;
+	bool ok;
+
+retry:
+	cond_resched();
+	rcu_read_lock();
+	ok = !__netlink_lookup(table, portid, net);
+	rcu_read_unlock();
+	if (!ok) {
+		/* Bind collision, search negative portid values. */
+		if (rover == -4096)
+			/* rover will be in range [S32_MIN, -4097] */
+			rover = S32_MIN + prandom_u32_max(-4096 - S32_MIN);
+		else if (rover >= -4096)
+			rover = -4097;
+		portid = rover--;
+		goto retry;
+	}
+
+	err = netlink_insert(sk, portid);
+	if (err == -EADDRINUSE)
+		goto retry;
+
+	/* If 2 threads race to autobind, that is fine.  */
+	if (err == -EBUSY)
+		err = 0;
+
+	return err;
+}
+
+/**
+ * __netlink_ns_capable - General netlink message capability test
+ * @nsp: NETLINK_CB of the socket buffer holding a netlink command from userspace.
+ * @user_ns: The user namespace of the capability to use
+ * @cap: The capability to use
+ *
+ * Test to see if the opener of the socket we received the message
+ * from had when the netlink socket was created and the sender of the
+ * message has the capability @cap in the user namespace @user_ns.
+ */
+bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
+			struct user_namespace *user_ns, int cap)
+{
+	return ((nsp->flags & NETLINK_SKB_DST) ||
+		file_ns_capable(nsp->sk->sk_socket->file, user_ns, cap)) &&
+		ns_capable(user_ns, cap);
+}
+EXPORT_SYMBOL(__netlink_ns_capable);
+
+/**
+ * netlink_ns_capable - General netlink message capability test
+ * @skb: socket buffer holding a netlink command from userspace
+ * @user_ns: The user namespace of the capability to use
+ * @cap: The capability to use
+ *
+ * Test to see if the opener of the socket we received the message
+ * from had when the netlink socket was created and the sender of the
+ * message has the capability @cap in the user namespace @user_ns.
+ */
+bool netlink_ns_capable(const struct sk_buff *skb,
+			struct user_namespace *user_ns, int cap)
+{
+	return __netlink_ns_capable(&NETLINK_CB(skb), user_ns, cap);
+}
+EXPORT_SYMBOL(netlink_ns_capable);
+
+/**
+ * netlink_capable - Netlink global message capability test
+ * @skb: socket buffer holding a netlink command from userspace
+ * @cap: The capability to use
+ *
+ * Test to see if the opener of the socket we received the message
+ * from had when the netlink socket was created and the sender of the
+ * message has the capability @cap in all user namespaces.
+ */
+bool netlink_capable(const struct sk_buff *skb, int cap)
+{
+	return netlink_ns_capable(skb, &init_user_ns, cap);
+}
+EXPORT_SYMBOL(netlink_capable);
+
+/**
+ * netlink_net_capable - Netlink network namespace message capability test
+ * @skb: socket buffer holding a netlink command from userspace
+ * @cap: The capability to use
+ *
+ * Test to see if the opener of the socket we received the message
+ * from had when the netlink socket was created and the sender of the
+ * message has the capability @cap over the network namespace of
+ * the socket we received the message from.
+ */
+bool netlink_net_capable(const struct sk_buff *skb, int cap)
+{
+	return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap);
+}
+EXPORT_SYMBOL(netlink_net_capable);
+
+static inline int netlink_allowed(const struct socket *sock, unsigned int flag)
+{
+	return (nl_table[sock->sk->sk_protocol].flags & flag) ||
+		ns_capable(sock_net(sock->sk)->user_ns, CAP_NET_ADMIN);
+}
+
+static void
+netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+
+	if (nlk->subscriptions && !subscriptions)
+		__sk_del_bind_node(sk);
+	else if (!nlk->subscriptions && subscriptions)
+		sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
+	nlk->subscriptions = subscriptions;
+}
+
+static int netlink_realloc_groups(struct sock *sk)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+	unsigned int groups;
+	unsigned long *new_groups;
+	int err = 0;
+
+	netlink_table_grab();
+
+	groups = nl_table[sk->sk_protocol].groups;
+	if (!nl_table[sk->sk_protocol].registered) {
+		err = -ENOENT;
+		goto out_unlock;
+	}
+
+	if (nlk->ngroups >= groups)
+		goto out_unlock;
+
+	new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
+	if (new_groups == NULL) {
+		err = -ENOMEM;
+		goto out_unlock;
+	}
+	memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
+	       NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
+
+	nlk->groups = new_groups;
+	nlk->ngroups = groups;
+ out_unlock:
+	netlink_table_ungrab();
+	return err;
+}
+
+static void netlink_undo_bind(int group, long unsigned int groups,
+			      struct sock *sk)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+	int undo;
+
+	if (!nlk->netlink_unbind)
+		return;
+
+	for (undo = 0; undo < group; undo++)
+		if (test_bit(undo, &groups))
+			nlk->netlink_unbind(sock_net(sk), undo + 1);
+}
+
+static int netlink_bind(struct socket *sock, struct sockaddr *addr,
+			int addr_len)
+{
+	struct sock *sk = sock->sk;
+	struct net *net = sock_net(sk);
+	struct netlink_sock *nlk = nlk_sk(sk);
+	struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
+	int err = 0;
+	unsigned long groups;
+	bool bound;
+
+	if (addr_len < sizeof(struct sockaddr_nl))
+		return -EINVAL;
+
+	if (nladdr->nl_family != AF_NETLINK)
+		return -EINVAL;
+	groups = nladdr->nl_groups;
+
+	/* Only superuser is allowed to listen multicasts */
+	if (groups) {
+		if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
+			return -EPERM;
+		err = netlink_realloc_groups(sk);
+		if (err)
+			return err;
+	}
+
+	if (nlk->ngroups < BITS_PER_LONG)
+		groups &= (1UL << nlk->ngroups) - 1;
+
+	/* Paired with WRITE_ONCE() in netlink_insert() */
+	bound = READ_ONCE(nlk->bound);
+	if (bound) {
+		/* Ensure nlk->portid is up-to-date. */
+		smp_rmb();
+
+		if (nladdr->nl_pid != nlk->portid)
+			return -EINVAL;
+	}
+
+	if (nlk->netlink_bind && groups) {
+		int group;
+
+		/* nl_groups is a u32, so cap the maximum groups we can bind */
+		for (group = 0; group < BITS_PER_TYPE(u32); group++) {
+			if (!test_bit(group, &groups))
+				continue;
+			err = nlk->netlink_bind(net, group + 1);
+			if (!err)
+				continue;
+			netlink_undo_bind(group, groups, sk);
+			return err;
+		}
+	}
+
+	/* No need for barriers here as we return to user-space without
+	 * using any of the bound attributes.
+	 */
+	netlink_lock_table();
+	if (!bound) {
+		err = nladdr->nl_pid ?
+			netlink_insert(sk, nladdr->nl_pid) :
+			netlink_autobind(sock);
+		if (err) {
+			netlink_undo_bind(BITS_PER_TYPE(u32), groups, sk);
+			goto unlock;
+		}
+	}
+
+	if (!groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
+		goto unlock;
+	netlink_unlock_table();
+
+	netlink_table_grab();
+	netlink_update_subscriptions(sk, nlk->subscriptions +
+					 hweight32(groups) -
+					 hweight32(nlk->groups[0]));
+	nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | groups;
+	netlink_update_listeners(sk);
+	netlink_table_ungrab();
+
+	return 0;
+
+unlock:
+	netlink_unlock_table();
+	return err;
+}
+
+static int netlink_connect(struct socket *sock, struct sockaddr *addr,
+			   int alen, int flags)
+{
+	int err = 0;
+	struct sock *sk = sock->sk;
+	struct netlink_sock *nlk = nlk_sk(sk);
+	struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
+
+	if (alen < sizeof(addr->sa_family))
+		return -EINVAL;
+
+	if (addr->sa_family == AF_UNSPEC) {
+		/* paired with READ_ONCE() in netlink_getsockbyportid() */
+		WRITE_ONCE(sk->sk_state, NETLINK_UNCONNECTED);
+		/* dst_portid and dst_group can be read locklessly */
+		WRITE_ONCE(nlk->dst_portid, 0);
+		WRITE_ONCE(nlk->dst_group, 0);
+		return 0;
+	}
+	if (addr->sa_family != AF_NETLINK)
+		return -EINVAL;
+
+	if (alen < sizeof(struct sockaddr_nl))
+		return -EINVAL;
+
+	if ((nladdr->nl_groups || nladdr->nl_pid) &&
+	    !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
+		return -EPERM;
+
+	/* No need for barriers here as we return to user-space without
+	 * using any of the bound attributes.
+	 * Paired with WRITE_ONCE() in netlink_insert().
+	 */
+	if (!READ_ONCE(nlk->bound))
+		err = netlink_autobind(sock);
+
+	if (err == 0) {
+		/* paired with READ_ONCE() in netlink_getsockbyportid() */
+		WRITE_ONCE(sk->sk_state, NETLINK_CONNECTED);
+		/* dst_portid and dst_group can be read locklessly */
+		WRITE_ONCE(nlk->dst_portid, nladdr->nl_pid);
+		WRITE_ONCE(nlk->dst_group, ffs(nladdr->nl_groups));
+	}
+
+	return err;
+}
+
+static int netlink_getname(struct socket *sock, struct sockaddr *addr,
+			   int peer)
+{
+	struct sock *sk = sock->sk;
+	struct netlink_sock *nlk = nlk_sk(sk);
+	DECLARE_SOCKADDR(struct sockaddr_nl *, nladdr, addr);
+
+	nladdr->nl_family = AF_NETLINK;
+	nladdr->nl_pad = 0;
+
+	if (peer) {
+		/* Paired with WRITE_ONCE() in netlink_connect() */
+		nladdr->nl_pid = READ_ONCE(nlk->dst_portid);
+		nladdr->nl_groups = netlink_group_mask(READ_ONCE(nlk->dst_group));
+	} else {
+		/* Paired with WRITE_ONCE() in netlink_insert() */
+		nladdr->nl_pid = READ_ONCE(nlk->portid);
+		netlink_lock_table();
+		nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
+		netlink_unlock_table();
+	}
+	return sizeof(*nladdr);
+}
+
+static int netlink_ioctl(struct socket *sock, unsigned int cmd,
+			 unsigned long arg)
+{
+	/* try to hand this ioctl down to the NIC drivers.
+	 */
+	return -ENOIOCTLCMD;
+}
+
+static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
+{
+	struct sock *sock;
+	struct netlink_sock *nlk;
+
+	sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, portid);
+	if (!sock)
+		return ERR_PTR(-ECONNREFUSED);
+
+	/* Don't bother queuing skb if kernel socket has no input function */
+	nlk = nlk_sk(sock);
+	/* dst_portid and sk_state can be changed in netlink_connect() */
+	if (READ_ONCE(sock->sk_state) == NETLINK_CONNECTED &&
+	    READ_ONCE(nlk->dst_portid) != nlk_sk(ssk)->portid) {
+		sock_put(sock);
+		return ERR_PTR(-ECONNREFUSED);
+	}
+	return sock;
+}
+
+struct sock *netlink_getsockbyfilp(struct file *filp)
+{
+	struct inode *inode = file_inode(filp);
+	struct sock *sock;
+
+	if (!S_ISSOCK(inode->i_mode))
+		return ERR_PTR(-ENOTSOCK);
+
+	sock = SOCKET_I(inode)->sk;
+	if (sock->sk_family != AF_NETLINK)
+		return ERR_PTR(-EINVAL);
+
+	sock_hold(sock);
+	return sock;
+}
+
+static struct sk_buff *netlink_alloc_large_skb(unsigned int size,
+					       int broadcast)
+{
+	struct sk_buff *skb;
+	void *data;
+
+	if (size <= NLMSG_GOODSIZE || broadcast)
+		return alloc_skb(size, GFP_KERNEL);
+
+	size = SKB_DATA_ALIGN(size) +
+	       SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+
+	data = vmalloc(size);
+	if (data == NULL)
+		return NULL;
+
+	skb = __build_skb(data, size);
+	if (skb == NULL)
+		vfree(data);
+	else
+		skb->destructor = netlink_skb_destructor;
+
+	return skb;
+}
+
+/*
+ * Attach a skb to a netlink socket.
+ * The caller must hold a reference to the destination socket. On error, the
+ * reference is dropped. The skb is not send to the destination, just all
+ * all error checks are performed and memory in the queue is reserved.
+ * Return values:
+ * < 0: error. skb freed, reference to sock dropped.
+ * 0: continue
+ * 1: repeat lookup - reference dropped while waiting for socket memory.
+ */
+int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
+		      long *timeo, struct sock *ssk)
+{
+	struct netlink_sock *nlk;
+
+	nlk = nlk_sk(sk);
+
+	if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
+	     test_bit(NETLINK_S_CONGESTED, &nlk->state))) {
+		DECLARE_WAITQUEUE(wait, current);
+		if (!*timeo) {
+			if (!ssk || netlink_is_kernel(ssk))
+				netlink_overrun(sk);
+			sock_put(sk);
+			kfree_skb(skb);
+			return -EAGAIN;
+		}
+
+		__set_current_state(TASK_INTERRUPTIBLE);
+		add_wait_queue(&nlk->wait, &wait);
+
+		if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
+		     test_bit(NETLINK_S_CONGESTED, &nlk->state)) &&
+		    !sock_flag(sk, SOCK_DEAD))
+			*timeo = schedule_timeout(*timeo);
+
+		__set_current_state(TASK_RUNNING);
+		remove_wait_queue(&nlk->wait, &wait);
+		sock_put(sk);
+
+		if (signal_pending(current)) {
+			kfree_skb(skb);
+			return sock_intr_errno(*timeo);
+		}
+		return 1;
+	}
+	netlink_skb_set_owner_r(skb, sk);
+	return 0;
+}
+
+static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb)
+{
+	int len = skb->len;
+
+	netlink_deliver_tap(sock_net(sk), skb);
+
+	skb_queue_tail(&sk->sk_receive_queue, skb);
+	sk->sk_data_ready(sk);
+	return len;
+}
+
+int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
+{
+	int len = __netlink_sendskb(sk, skb);
+
+	sock_put(sk);
+	return len;
+}
+
+void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
+{
+	kfree_skb(skb);
+	sock_put(sk);
+}
+
+static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
+{
+	int delta;
+
+	WARN_ON(skb->sk != NULL);
+	delta = skb->end - skb->tail;
+	if (is_vmalloc_addr(skb->head) || delta * 2 < skb->truesize)
+		return skb;
+
+	if (skb_shared(skb)) {
+		struct sk_buff *nskb = skb_clone(skb, allocation);
+		if (!nskb)
+			return skb;
+		consume_skb(skb);
+		skb = nskb;
+	}
+
+	pskb_expand_head(skb, 0, -delta,
+			 (allocation & ~__GFP_DIRECT_RECLAIM) |
+			 __GFP_NOWARN | __GFP_NORETRY);
+	return skb;
+}
+
+static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
+				  struct sock *ssk)
+{
+	int ret;
+	struct netlink_sock *nlk = nlk_sk(sk);
+
+	ret = -ECONNREFUSED;
+	if (nlk->netlink_rcv != NULL) {
+		ret = skb->len;
+		netlink_skb_set_owner_r(skb, sk);
+		NETLINK_CB(skb).sk = ssk;
+		netlink_deliver_tap_kernel(sk, ssk, skb);
+		nlk->netlink_rcv(skb);
+		consume_skb(skb);
+	} else {
+		kfree_skb(skb);
+	}
+	sock_put(sk);
+	return ret;
+}
+
+int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
+		    u32 portid, int nonblock)
+{
+	struct sock *sk;
+	int err;
+	long timeo;
+
+	skb = netlink_trim(skb, gfp_any());
+
+	timeo = sock_sndtimeo(ssk, nonblock);
+retry:
+	sk = netlink_getsockbyportid(ssk, portid);
+	if (IS_ERR(sk)) {
+		kfree_skb(skb);
+		return PTR_ERR(sk);
+	}
+	if (netlink_is_kernel(sk))
+		return netlink_unicast_kernel(sk, skb, ssk);
+
+	if (sk_filter(sk, skb)) {
+		err = skb->len;
+		kfree_skb(skb);
+		sock_put(sk);
+		return err;
+	}
+
+	err = netlink_attachskb(sk, skb, &timeo, ssk);
+	if (err == 1)
+		goto retry;
+	if (err)
+		return err;
+
+	return netlink_sendskb(sk, skb);
+}
+EXPORT_SYMBOL(netlink_unicast);
+
+int netlink_has_listeners(struct sock *sk, unsigned int group)
+{
+	int res = 0;
+	struct listeners *listeners;
+
+	BUG_ON(!netlink_is_kernel(sk));
+
+	rcu_read_lock();
+	listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
+
+	if (listeners && group - 1 < nl_table[sk->sk_protocol].groups)
+		res = test_bit(group - 1, listeners->masks);
+
+	rcu_read_unlock();
+
+	return res;
+}
+EXPORT_SYMBOL_GPL(netlink_has_listeners);
+
+bool netlink_strict_get_check(struct sk_buff *skb)
+{
+	return nlk_test_bit(STRICT_CHK, NETLINK_CB(skb).sk);
+}
+EXPORT_SYMBOL_GPL(netlink_strict_get_check);
+
+static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+
+	if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
+	    !test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
+		netlink_skb_set_owner_r(skb, sk);
+		__netlink_sendskb(sk, skb);
+		return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
+	}
+	return -1;
+}
+
+struct netlink_broadcast_data {
+	struct sock *exclude_sk;
+	struct net *net;
+	u32 portid;
+	u32 group;
+	int failure;
+	int delivery_failure;
+	int congested;
+	int delivered;
+	gfp_t allocation;
+	struct sk_buff *skb, *skb2;
+};
+
+static void do_one_broadcast(struct sock *sk,
+				    struct netlink_broadcast_data *p)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+	int val;
+
+	if (p->exclude_sk == sk)
+		return;
+
+	if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
+	    !test_bit(p->group - 1, nlk->groups))
+		return;
+
+	if (!net_eq(sock_net(sk), p->net)) {
+		if (!nlk_test_bit(LISTEN_ALL_NSID, sk))
+			return;
+
+		if (!peernet_has_id(sock_net(sk), p->net))
+			return;
+
+		if (!file_ns_capable(sk->sk_socket->file, p->net->user_ns,
+				     CAP_NET_BROADCAST))
+			return;
+	}
+
+	if (p->failure) {
+		netlink_overrun(sk);
+		return;
+	}
+
+	sock_hold(sk);
+	if (p->skb2 == NULL) {
+		if (skb_shared(p->skb)) {
+			p->skb2 = skb_clone(p->skb, p->allocation);
+		} else {
+			p->skb2 = skb_get(p->skb);
+			/*
+			 * skb ownership may have been set when
+			 * delivered to a previous socket.
+			 */
+			skb_orphan(p->skb2);
+		}
+	}
+	if (p->skb2 == NULL) {
+		netlink_overrun(sk);
+		/* Clone failed. Notify ALL listeners. */
+		p->failure = 1;
+		if (nlk_test_bit(BROADCAST_SEND_ERROR, sk))
+			p->delivery_failure = 1;
+		goto out;
+	}
+	if (sk_filter(sk, p->skb2)) {
+		kfree_skb(p->skb2);
+		p->skb2 = NULL;
+		goto out;
+	}
+	NETLINK_CB(p->skb2).nsid = peernet2id(sock_net(sk), p->net);
+	if (NETLINK_CB(p->skb2).nsid != NETNSA_NSID_NOT_ASSIGNED)
+		NETLINK_CB(p->skb2).nsid_is_set = true;
+	val = netlink_broadcast_deliver(sk, p->skb2);
+	if (val < 0) {
+		netlink_overrun(sk);
+		if (nlk_test_bit(BROADCAST_SEND_ERROR, sk))
+			p->delivery_failure = 1;
+	} else {
+		p->congested |= val;
+		p->delivered = 1;
+		p->skb2 = NULL;
+	}
+out:
+	sock_put(sk);
+}
+
+int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
+		      u32 group, gfp_t allocation)
+{
+	struct net *net = sock_net(ssk);
+	struct netlink_broadcast_data info;
+	struct sock *sk;
+
+	skb = netlink_trim(skb, allocation);
+
+	info.exclude_sk = ssk;
+	info.net = net;
+	info.portid = portid;
+	info.group = group;
+	info.failure = 0;
+	info.delivery_failure = 0;
+	info.congested = 0;
+	info.delivered = 0;
+	info.allocation = allocation;
+	info.skb = skb;
+	info.skb2 = NULL;
+
+	/* While we sleep in clone, do not allow to change socket list */
+
+	netlink_lock_table();
+
+	sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
+		do_one_broadcast(sk, &info);
+
+	consume_skb(skb);
+
+	netlink_unlock_table();
+
+	if (info.delivery_failure) {
+		kfree_skb(info.skb2);
+		return -ENOBUFS;
+	}
+	consume_skb(info.skb2);
+
+	if (info.delivered) {
+		if (info.congested && gfpflags_allow_blocking(allocation))
+			yield();
+		return 0;
+	}
+	return -ESRCH;
+}
+EXPORT_SYMBOL(netlink_broadcast);
+
+struct netlink_set_err_data {
+	struct sock *exclude_sk;
+	u32 portid;
+	u32 group;
+	int code;
+};
+
+static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+	int ret = 0;
+
+	if (sk == p->exclude_sk)
+		goto out;
+
+	if (!net_eq(sock_net(sk), sock_net(p->exclude_sk)))
+		goto out;
+
+	if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
+	    !test_bit(p->group - 1, nlk->groups))
+		goto out;
+
+	if (p->code == ENOBUFS && nlk_test_bit(RECV_NO_ENOBUFS, sk)) {
+		ret = 1;
+		goto out;
+	}
+
+	WRITE_ONCE(sk->sk_err, p->code);
+	sk_error_report(sk);
+out:
+	return ret;
+}
+
+/**
+ * netlink_set_err - report error to broadcast listeners
+ * @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
+ * @portid: the PORTID of a process that we want to skip (if any)
+ * @group: the broadcast group that will notice the error
+ * @code: error code, must be negative (as usual in kernelspace)
+ *
+ * This function returns the number of broadcast listeners that have set the
+ * NETLINK_NO_ENOBUFS socket option.
+ */
+int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code)
+{
+	struct netlink_set_err_data info;
+	unsigned long flags;
+	struct sock *sk;
+	int ret = 0;
+
+	info.exclude_sk = ssk;
+	info.portid = portid;
+	info.group = group;
+	/* sk->sk_err wants a positive error value */
+	info.code = -code;
+
+	read_lock_irqsave(&nl_table_lock, flags);
+
+	sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
+		ret += do_one_set_err(sk, &info);
+
+	read_unlock_irqrestore(&nl_table_lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL(netlink_set_err);
+
+/* must be called with netlink table grabbed */
+static void netlink_update_socket_mc(struct netlink_sock *nlk,
+				     unsigned int group,
+				     int is_new)
+{
+	int old, new = !!is_new, subscriptions;
+
+	old = test_bit(group - 1, nlk->groups);
+	subscriptions = nlk->subscriptions - old + new;
+	if (new)
+		__set_bit(group - 1, nlk->groups);
+	else
+		__clear_bit(group - 1, nlk->groups);
+	netlink_update_subscriptions(&nlk->sk, subscriptions);
+	netlink_update_listeners(&nlk->sk);
+}
+
+static int netlink_setsockopt(struct socket *sock, int level, int optname,
+			      sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = sock->sk;
+	struct netlink_sock *nlk = nlk_sk(sk);
+	unsigned int val = 0;
+	int nr = -1;
+
+	if (level != SOL_NETLINK)
+		return -ENOPROTOOPT;
+
+	if (optlen >= sizeof(int) &&
+	    copy_from_sockptr(&val, optval, sizeof(val)))
+		return -EFAULT;
+
+	switch (optname) {
+	case NETLINK_PKTINFO:
+		nr = NETLINK_F_RECV_PKTINFO;
+		break;
+	case NETLINK_ADD_MEMBERSHIP:
+	case NETLINK_DROP_MEMBERSHIP: {
+		int err;
+
+		if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
+			return -EPERM;
+		err = netlink_realloc_groups(sk);
+		if (err)
+			return err;
+		if (!val || val - 1 >= nlk->ngroups)
+			return -EINVAL;
+		if (optname == NETLINK_ADD_MEMBERSHIP && nlk->netlink_bind) {
+			err = nlk->netlink_bind(sock_net(sk), val);
+			if (err)
+				return err;
+		}
+		netlink_table_grab();
+		netlink_update_socket_mc(nlk, val,
+					 optname == NETLINK_ADD_MEMBERSHIP);
+		netlink_table_ungrab();
+		if (optname == NETLINK_DROP_MEMBERSHIP && nlk->netlink_unbind)
+			nlk->netlink_unbind(sock_net(sk), val);
+
+		break;
+	}
+	case NETLINK_BROADCAST_ERROR:
+		nr = NETLINK_F_BROADCAST_SEND_ERROR;
+		break;
+	case NETLINK_NO_ENOBUFS:
+		assign_bit(NETLINK_F_RECV_NO_ENOBUFS, &nlk->flags, val);
+		if (val) {
+			clear_bit(NETLINK_S_CONGESTED, &nlk->state);
+			wake_up_interruptible(&nlk->wait);
+		}
+		break;
+	case NETLINK_LISTEN_ALL_NSID:
+		if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_BROADCAST))
+			return -EPERM;
+		nr = NETLINK_F_LISTEN_ALL_NSID;
+		break;
+	case NETLINK_CAP_ACK:
+		nr = NETLINK_F_CAP_ACK;
+		break;
+	case NETLINK_EXT_ACK:
+		nr = NETLINK_F_EXT_ACK;
+		break;
+	case NETLINK_GET_STRICT_CHK:
+		nr = NETLINK_F_STRICT_CHK;
+		break;
+	default:
+		return -ENOPROTOOPT;
+	}
+	if (nr >= 0)
+		assign_bit(nr, &nlk->flags, val);
+	return 0;
+}
+
+static int netlink_getsockopt(struct socket *sock, int level, int optname,
+			      char __user *optval, int __user *optlen)
+{
+	struct sock *sk = sock->sk;
+	struct netlink_sock *nlk = nlk_sk(sk);
+	unsigned int flag;
+	int len, val;
+
+	if (level != SOL_NETLINK)
+		return -ENOPROTOOPT;
+
+	if (get_user(len, optlen))
+		return -EFAULT;
+	if (len < 0)
+		return -EINVAL;
+
+	switch (optname) {
+	case NETLINK_PKTINFO:
+		flag = NETLINK_F_RECV_PKTINFO;
+		break;
+	case NETLINK_BROADCAST_ERROR:
+		flag = NETLINK_F_BROADCAST_SEND_ERROR;
+		break;
+	case NETLINK_NO_ENOBUFS:
+		flag = NETLINK_F_RECV_NO_ENOBUFS;
+		break;
+	case NETLINK_LIST_MEMBERSHIPS: {
+		int pos, idx, shift, err = 0;
+
+		netlink_lock_table();
+		for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) {
+			if (len - pos < sizeof(u32))
+				break;
+
+			idx = pos / sizeof(unsigned long);
+			shift = (pos % sizeof(unsigned long)) * 8;
+			if (put_user((u32)(nlk->groups[idx] >> shift),
+				     (u32 __user *)(optval + pos))) {
+				err = -EFAULT;
+				break;
+			}
+		}
+		if (put_user(ALIGN(BITS_TO_BYTES(nlk->ngroups), sizeof(u32)), optlen))
+			err = -EFAULT;
+		netlink_unlock_table();
+		return err;
+	}
+	case NETLINK_CAP_ACK:
+		flag = NETLINK_F_CAP_ACK;
+		break;
+	case NETLINK_EXT_ACK:
+		flag = NETLINK_F_EXT_ACK;
+		break;
+	case NETLINK_GET_STRICT_CHK:
+		flag = NETLINK_F_STRICT_CHK;
+		break;
+	default:
+		return -ENOPROTOOPT;
+	}
+
+	if (len < sizeof(int))
+		return -EINVAL;
+
+	len = sizeof(int);
+	val = test_bit(flag, &nlk->flags);
+
+	if (put_user(len, optlen) ||
+	    copy_to_user(optval, &val, len))
+		return -EFAULT;
+
+	return 0;
+}
+
+static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
+{
+	struct nl_pktinfo info;
+
+	info.group = NETLINK_CB(skb).dst_group;
+	put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
+}
+
+static void netlink_cmsg_listen_all_nsid(struct sock *sk, struct msghdr *msg,
+					 struct sk_buff *skb)
+{
+	if (!NETLINK_CB(skb).nsid_is_set)
+		return;
+
+	put_cmsg(msg, SOL_NETLINK, NETLINK_LISTEN_ALL_NSID, sizeof(int),
+		 &NETLINK_CB(skb).nsid);
+}
+
+static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
+{
+	struct sock *sk = sock->sk;
+	struct netlink_sock *nlk = nlk_sk(sk);
+	DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
+	u32 dst_portid;
+	u32 dst_group;
+	struct sk_buff *skb;
+	int err;
+	struct scm_cookie scm;
+	u32 netlink_skb_flags = 0;
+
+	if (msg->msg_flags & MSG_OOB)
+		return -EOPNOTSUPP;
+
+	if (len == 0) {
+		pr_warn_once("Zero length message leads to an empty skb\n");
+		return -ENODATA;
+	}
+
+	err = scm_send(sock, msg, &scm, true);
+	if (err < 0)
+		return err;
+
+	if (msg->msg_namelen) {
+		err = -EINVAL;
+		if (msg->msg_namelen < sizeof(struct sockaddr_nl))
+			goto out;
+		if (addr->nl_family != AF_NETLINK)
+			goto out;
+		dst_portid = addr->nl_pid;
+		dst_group = ffs(addr->nl_groups);
+		err =  -EPERM;
+		if ((dst_group || dst_portid) &&
+		    !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
+			goto out;
+		netlink_skb_flags |= NETLINK_SKB_DST;
+	} else {
+		/* Paired with WRITE_ONCE() in netlink_connect() */
+		dst_portid = READ_ONCE(nlk->dst_portid);
+		dst_group = READ_ONCE(nlk->dst_group);
+	}
+
+	/* Paired with WRITE_ONCE() in netlink_insert() */
+	if (!READ_ONCE(nlk->bound)) {
+		err = netlink_autobind(sock);
+		if (err)
+			goto out;
+	} else {
+		/* Ensure nlk is hashed and visible. */
+		smp_rmb();
+	}
+
+	err = -EMSGSIZE;
+	if (len > sk->sk_sndbuf - 32)
+		goto out;
+	err = -ENOBUFS;
+	skb = netlink_alloc_large_skb(len, dst_group);
+	if (skb == NULL)
+		goto out;
+
+	NETLINK_CB(skb).portid	= nlk->portid;
+	NETLINK_CB(skb).dst_group = dst_group;
+	NETLINK_CB(skb).creds	= scm.creds;
+	NETLINK_CB(skb).flags	= netlink_skb_flags;
+
+	err = -EFAULT;
+	if (memcpy_from_msg(skb_put(skb, len), msg, len)) {
+		kfree_skb(skb);
+		goto out;
+	}
+
+	err = security_netlink_send(sk, skb);
+	if (err) {
+		kfree_skb(skb);
+		goto out;
+	}
+
+	if (dst_group) {
+		refcount_inc(&skb->users);
+		netlink_broadcast(sk, skb, dst_portid, dst_group, GFP_KERNEL);
+	}
+	err = netlink_unicast(sk, skb, dst_portid, msg->msg_flags & MSG_DONTWAIT);
+
+out:
+	scm_destroy(&scm);
+	return err;
+}
+
+static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
+			   int flags)
+{
+	struct scm_cookie scm;
+	struct sock *sk = sock->sk;
+	struct netlink_sock *nlk = nlk_sk(sk);
+	size_t copied, max_recvmsg_len;
+	struct sk_buff *skb, *data_skb;
+	int err, ret;
+
+	if (flags & MSG_OOB)
+		return -EOPNOTSUPP;
+
+	copied = 0;
+
+	skb = skb_recv_datagram(sk, flags, &err);
+	if (skb == NULL)
+		goto out;
+
+	data_skb = skb;
+
+#ifdef CONFIG_COMPAT_NETLINK_MESSAGES
+	if (unlikely(skb_shinfo(skb)->frag_list)) {
+		/*
+		 * If this skb has a frag_list, then here that means that we
+		 * will have to use the frag_list skb's data for compat tasks
+		 * and the regular skb's data for normal (non-compat) tasks.
+		 *
+		 * If we need to send the compat skb, assign it to the
+		 * 'data_skb' variable so that it will be used below for data
+		 * copying. We keep 'skb' for everything else, including
+		 * freeing both later.
+		 */
+		if (flags & MSG_CMSG_COMPAT)
+			data_skb = skb_shinfo(skb)->frag_list;
+	}
+#endif
+
+	/* Record the max length of recvmsg() calls for future allocations */
+	max_recvmsg_len = max(READ_ONCE(nlk->max_recvmsg_len), len);
+	max_recvmsg_len = min_t(size_t, max_recvmsg_len,
+				SKB_WITH_OVERHEAD(32768));
+	WRITE_ONCE(nlk->max_recvmsg_len, max_recvmsg_len);
+
+	copied = data_skb->len;
+	if (len < copied) {
+		msg->msg_flags |= MSG_TRUNC;
+		copied = len;
+	}
+
+	err = skb_copy_datagram_msg(data_skb, 0, msg, copied);
+
+	if (msg->msg_name) {
+		DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
+		addr->nl_family = AF_NETLINK;
+		addr->nl_pad    = 0;
+		addr->nl_pid	= NETLINK_CB(skb).portid;
+		addr->nl_groups	= netlink_group_mask(NETLINK_CB(skb).dst_group);
+		msg->msg_namelen = sizeof(*addr);
+	}
+
+	if (nlk_test_bit(RECV_PKTINFO, sk))
+		netlink_cmsg_recv_pktinfo(msg, skb);
+	if (nlk_test_bit(LISTEN_ALL_NSID, sk))
+		netlink_cmsg_listen_all_nsid(sk, msg, skb);
+
+	memset(&scm, 0, sizeof(scm));
+	scm.creds = *NETLINK_CREDS(skb);
+	if (flags & MSG_TRUNC)
+		copied = data_skb->len;
+
+	skb_free_datagram(sk, skb);
+
+	if (READ_ONCE(nlk->cb_running) &&
+	    atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
+		ret = netlink_dump(sk);
+		if (ret) {
+			WRITE_ONCE(sk->sk_err, -ret);
+			sk_error_report(sk);
+		}
+	}
+
+	scm_recv(sock, msg, &scm, flags);
+out:
+	netlink_rcv_wake(sk);
+	return err ? : copied;
+}
+
+static void netlink_data_ready(struct sock *sk)
+{
+	BUG();
+}
+
+/*
+ *	We export these functions to other modules. They provide a
+ *	complete set of kernel non-blocking support for message
+ *	queueing.
+ */
+
+struct sock *
+__netlink_kernel_create(struct net *net, int unit, struct module *module,
+			struct netlink_kernel_cfg *cfg)
+{
+	struct socket *sock;
+	struct sock *sk;
+	struct netlink_sock *nlk;
+	struct listeners *listeners = NULL;
+	struct mutex *cb_mutex = cfg ? cfg->cb_mutex : NULL;
+	unsigned int groups;
+
+	BUG_ON(!nl_table);
+
+	if (unit < 0 || unit >= MAX_LINKS)
+		return NULL;
+
+	if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
+		return NULL;
+
+	if (__netlink_create(net, sock, cb_mutex, unit, 1) < 0)
+		goto out_sock_release_nosk;
+
+	sk = sock->sk;
+
+	if (!cfg || cfg->groups < 32)
+		groups = 32;
+	else
+		groups = cfg->groups;
+
+	listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
+	if (!listeners)
+		goto out_sock_release;
+
+	sk->sk_data_ready = netlink_data_ready;
+	if (cfg && cfg->input)
+		nlk_sk(sk)->netlink_rcv = cfg->input;
+
+	if (netlink_insert(sk, 0))
+		goto out_sock_release;
+
+	nlk = nlk_sk(sk);
+	set_bit(NETLINK_F_KERNEL_SOCKET, &nlk->flags);
+
+	netlink_table_grab();
+	if (!nl_table[unit].registered) {
+		nl_table[unit].groups = groups;
+		rcu_assign_pointer(nl_table[unit].listeners, listeners);
+		nl_table[unit].cb_mutex = cb_mutex;
+		nl_table[unit].module = module;
+		if (cfg) {
+			nl_table[unit].bind = cfg->bind;
+			nl_table[unit].unbind = cfg->unbind;
+			nl_table[unit].flags = cfg->flags;
+			if (cfg->compare)
+				nl_table[unit].compare = cfg->compare;
+		}
+		nl_table[unit].registered = 1;
+	} else {
+		kfree(listeners);
+		nl_table[unit].registered++;
+	}
+	netlink_table_ungrab();
+	return sk;
+
+out_sock_release:
+	kfree(listeners);
+	netlink_kernel_release(sk);
+	return NULL;
+
+out_sock_release_nosk:
+	sock_release(sock);
+	return NULL;
+}
+EXPORT_SYMBOL(__netlink_kernel_create);
+
+void
+netlink_kernel_release(struct sock *sk)
+{
+	if (sk == NULL || sk->sk_socket == NULL)
+		return;
+
+	sock_release(sk->sk_socket);
+}
+EXPORT_SYMBOL(netlink_kernel_release);
+
+int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
+{
+	struct listeners *new, *old;
+	struct netlink_table *tbl = &nl_table[sk->sk_protocol];
+
+	if (groups < 32)
+		groups = 32;
+
+	if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
+		new = kzalloc(sizeof(*new) + NLGRPSZ(groups), GFP_ATOMIC);
+		if (!new)
+			return -ENOMEM;
+		old = nl_deref_protected(tbl->listeners);
+		memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups));
+		rcu_assign_pointer(tbl->listeners, new);
+
+		kfree_rcu(old, rcu);
+	}
+	tbl->groups = groups;
+
+	return 0;
+}
+
+/**
+ * netlink_change_ngroups - change number of multicast groups
+ *
+ * This changes the number of multicast groups that are available
+ * on a certain netlink family. Note that it is not possible to
+ * change the number of groups to below 32. Also note that it does
+ * not implicitly call netlink_clear_multicast_users() when the
+ * number of groups is reduced.
+ *
+ * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
+ * @groups: The new number of groups.
+ */
+int netlink_change_ngroups(struct sock *sk, unsigned int groups)
+{
+	int err;
+
+	netlink_table_grab();
+	err = __netlink_change_ngroups(sk, groups);
+	netlink_table_ungrab();
+
+	return err;
+}
+
+void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
+{
+	struct sock *sk;
+	struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
+
+	sk_for_each_bound(sk, &tbl->mc_list)
+		netlink_update_socket_mc(nlk_sk(sk), group, 0);
+}
+
+struct nlmsghdr *
+__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags)
+{
+	struct nlmsghdr *nlh;
+	int size = nlmsg_msg_size(len);
+
+	nlh = skb_put(skb, NLMSG_ALIGN(size));
+	nlh->nlmsg_type = type;
+	nlh->nlmsg_len = size;
+	nlh->nlmsg_flags = flags;
+	nlh->nlmsg_pid = portid;
+	nlh->nlmsg_seq = seq;
+	if (!__builtin_constant_p(size) || NLMSG_ALIGN(size) - size != 0)
+		memset(nlmsg_data(nlh) + len, 0, NLMSG_ALIGN(size) - size);
+	return nlh;
+}
+EXPORT_SYMBOL(__nlmsg_put);
+
+/*
+ * It looks a bit ugly.
+ * It would be better to create kernel thread.
+ */
+
+static int netlink_dump_done(struct netlink_sock *nlk, struct sk_buff *skb,
+			     struct netlink_callback *cb,
+			     struct netlink_ext_ack *extack)
+{
+	struct nlmsghdr *nlh;
+
+	nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(nlk->dump_done_errno),
+			       NLM_F_MULTI | cb->answer_flags);
+	if (WARN_ON(!nlh))
+		return -ENOBUFS;
+
+	nl_dump_check_consistent(cb, nlh);
+	memcpy(nlmsg_data(nlh), &nlk->dump_done_errno, sizeof(nlk->dump_done_errno));
+
+	if (extack->_msg && test_bit(NETLINK_F_EXT_ACK, &nlk->flags)) {
+		nlh->nlmsg_flags |= NLM_F_ACK_TLVS;
+		if (!nla_put_string(skb, NLMSGERR_ATTR_MSG, extack->_msg))
+			nlmsg_end(skb, nlh);
+	}
+
+	return 0;
+}
+
+static int netlink_dump(struct sock *sk)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+	struct netlink_ext_ack extack = {};
+	struct netlink_callback *cb;
+	struct sk_buff *skb = NULL;
+	size_t max_recvmsg_len;
+	struct module *module;
+	int err = -ENOBUFS;
+	int alloc_min_size;
+	int alloc_size;
+
+	mutex_lock(nlk->cb_mutex);
+	if (!nlk->cb_running) {
+		err = -EINVAL;
+		goto errout_skb;
+	}
+
+	if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
+		goto errout_skb;
+
+	/* NLMSG_GOODSIZE is small to avoid high order allocations being
+	 * required, but it makes sense to _attempt_ a 16K bytes allocation
+	 * to reduce number of system calls on dump operations, if user
+	 * ever provided a big enough buffer.
+	 */
+	cb = &nlk->cb;
+	alloc_min_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
+
+	max_recvmsg_len = READ_ONCE(nlk->max_recvmsg_len);
+	if (alloc_min_size < max_recvmsg_len) {
+		alloc_size = max_recvmsg_len;
+		skb = alloc_skb(alloc_size,
+				(GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) |
+				__GFP_NOWARN | __GFP_NORETRY);
+	}
+	if (!skb) {
+		alloc_size = alloc_min_size;
+		skb = alloc_skb(alloc_size, GFP_KERNEL);
+	}
+	if (!skb)
+		goto errout_skb;
+
+	/* Trim skb to allocated size. User is expected to provide buffer as
+	 * large as max(min_dump_alloc, 16KiB (mac_recvmsg_len capped at
+	 * netlink_recvmsg())). dump will pack as many smaller messages as
+	 * could fit within the allocated skb. skb is typically allocated
+	 * with larger space than required (could be as much as near 2x the
+	 * requested size with align to next power of 2 approach). Allowing
+	 * dump to use the excess space makes it difficult for a user to have a
+	 * reasonable static buffer based on the expected largest dump of a
+	 * single netdev. The outcome is MSG_TRUNC error.
+	 */
+	skb_reserve(skb, skb_tailroom(skb) - alloc_size);
+
+	/* Make sure malicious BPF programs can not read unitialized memory
+	 * from skb->head -> skb->data
+	 */
+	skb_reset_network_header(skb);
+	skb_reset_mac_header(skb);
+
+	netlink_skb_set_owner_r(skb, sk);
+
+	if (nlk->dump_done_errno > 0) {
+		cb->extack = &extack;
+		nlk->dump_done_errno = cb->dump(skb, cb);
+		cb->extack = NULL;
+	}
+
+	if (nlk->dump_done_errno > 0 ||
+	    skb_tailroom(skb) < nlmsg_total_size(sizeof(nlk->dump_done_errno))) {
+		mutex_unlock(nlk->cb_mutex);
+
+		if (sk_filter(sk, skb))
+			kfree_skb(skb);
+		else
+			__netlink_sendskb(sk, skb);
+		return 0;
+	}
+
+	if (netlink_dump_done(nlk, skb, cb, &extack))
+		goto errout_skb;
+
+#ifdef CONFIG_COMPAT_NETLINK_MESSAGES
+	/* frag_list skb's data is used for compat tasks
+	 * and the regular skb's data for normal (non-compat) tasks.
+	 * See netlink_recvmsg().
+	 */
+	if (unlikely(skb_shinfo(skb)->frag_list)) {
+		if (netlink_dump_done(nlk, skb_shinfo(skb)->frag_list, cb, &extack))
+			goto errout_skb;
+	}
+#endif
+
+	if (sk_filter(sk, skb))
+		kfree_skb(skb);
+	else
+		__netlink_sendskb(sk, skb);
+
+	if (cb->done)
+		cb->done(cb);
+
+	WRITE_ONCE(nlk->cb_running, false);
+	module = cb->module;
+	skb = cb->skb;
+	mutex_unlock(nlk->cb_mutex);
+	module_put(module);
+	consume_skb(skb);
+	return 0;
+
+errout_skb:
+	mutex_unlock(nlk->cb_mutex);
+	kfree_skb(skb);
+	return err;
+}
+
+int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
+			 const struct nlmsghdr *nlh,
+			 struct netlink_dump_control *control)
+{
+	struct netlink_callback *cb;
+	struct netlink_sock *nlk;
+	struct sock *sk;
+	int ret;
+
+	refcount_inc(&skb->users);
+
+	sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);
+	if (sk == NULL) {
+		ret = -ECONNREFUSED;
+		goto error_free;
+	}
+
+	nlk = nlk_sk(sk);
+	mutex_lock(nlk->cb_mutex);
+	/* A dump is in progress... */
+	if (nlk->cb_running) {
+		ret = -EBUSY;
+		goto error_unlock;
+	}
+	/* add reference of module which cb->dump belongs to */
+	if (!try_module_get(control->module)) {
+		ret = -EPROTONOSUPPORT;
+		goto error_unlock;
+	}
+
+	cb = &nlk->cb;
+	memset(cb, 0, sizeof(*cb));
+	cb->dump = control->dump;
+	cb->done = control->done;
+	cb->nlh = nlh;
+	cb->data = control->data;
+	cb->module = control->module;
+	cb->min_dump_alloc = control->min_dump_alloc;
+	cb->skb = skb;
+
+	cb->strict_check = nlk_test_bit(STRICT_CHK, NETLINK_CB(skb).sk);
+
+	if (control->start) {
+		ret = control->start(cb);
+		if (ret)
+			goto error_put;
+	}
+
+	WRITE_ONCE(nlk->cb_running, true);
+	nlk->dump_done_errno = INT_MAX;
+
+	mutex_unlock(nlk->cb_mutex);
+
+	ret = netlink_dump(sk);
+
+	sock_put(sk);
+
+	if (ret)
+		return ret;
+
+	/* We successfully started a dump, by returning -EINTR we
+	 * signal not to send ACK even if it was requested.
+	 */
+	return -EINTR;
+
+error_put:
+	module_put(control->module);
+error_unlock:
+	sock_put(sk);
+	mutex_unlock(nlk->cb_mutex);
+error_free:
+	kfree_skb(skb);
+	return ret;
+}
+EXPORT_SYMBOL(__netlink_dump_start);
+
+static size_t
+netlink_ack_tlv_len(struct netlink_sock *nlk, int err,
+		    const struct netlink_ext_ack *extack)
+{
+	size_t tlvlen;
+
+	if (!extack || !test_bit(NETLINK_F_EXT_ACK, &nlk->flags))
+		return 0;
+
+	tlvlen = 0;
+	if (extack->_msg)
+		tlvlen += nla_total_size(strlen(extack->_msg) + 1);
+	if (extack->cookie_len)
+		tlvlen += nla_total_size(extack->cookie_len);
+
+	/* Following attributes are only reported as error (not warning) */
+	if (!err)
+		return tlvlen;
+
+	if (extack->bad_attr)
+		tlvlen += nla_total_size(sizeof(u32));
+	if (extack->policy)
+		tlvlen += netlink_policy_dump_attr_size_estimate(extack->policy);
+	if (extack->miss_type)
+		tlvlen += nla_total_size(sizeof(u32));
+	if (extack->miss_nest)
+		tlvlen += nla_total_size(sizeof(u32));
+
+	return tlvlen;
+}
+
+static void
+netlink_ack_tlv_fill(struct sk_buff *in_skb, struct sk_buff *skb,
+		     struct nlmsghdr *nlh, int err,
+		     const struct netlink_ext_ack *extack)
+{
+	if (extack->_msg)
+		WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG, extack->_msg));
+	if (extack->cookie_len)
+		WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
+				extack->cookie_len, extack->cookie));
+
+	if (!err)
+		return;
+
+	if (extack->bad_attr &&
+	    !WARN_ON((u8 *)extack->bad_attr < in_skb->data ||
+		     (u8 *)extack->bad_attr >= in_skb->data + in_skb->len))
+		WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
+				    (u8 *)extack->bad_attr - (u8 *)nlh));
+	if (extack->policy)
+		netlink_policy_dump_write_attr(skb, extack->policy,
+					       NLMSGERR_ATTR_POLICY);
+	if (extack->miss_type)
+		WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_MISS_TYPE,
+				    extack->miss_type));
+	if (extack->miss_nest &&
+	    !WARN_ON((u8 *)extack->miss_nest < in_skb->data ||
+		     (u8 *)extack->miss_nest > in_skb->data + in_skb->len))
+		WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_MISS_NEST,
+				    (u8 *)extack->miss_nest - (u8 *)nlh));
+}
+
+void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
+		 const struct netlink_ext_ack *extack)
+{
+	struct sk_buff *skb;
+	struct nlmsghdr *rep;
+	struct nlmsgerr *errmsg;
+	size_t payload = sizeof(*errmsg);
+	struct netlink_sock *nlk = nlk_sk(NETLINK_CB(in_skb).sk);
+	unsigned int flags = 0;
+	size_t tlvlen;
+
+	/* Error messages get the original request appened, unless the user
+	 * requests to cap the error message, and get extra error data if
+	 * requested.
+	 */
+	if (err && !test_bit(NETLINK_F_CAP_ACK, &nlk->flags))
+		payload += nlmsg_len(nlh);
+	else
+		flags |= NLM_F_CAPPED;
+
+	tlvlen = netlink_ack_tlv_len(nlk, err, extack);
+	if (tlvlen)
+		flags |= NLM_F_ACK_TLVS;
+
+	skb = nlmsg_new(payload + tlvlen, GFP_KERNEL);
+	if (!skb)
+		goto err_skb;
+
+	rep = nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
+			NLMSG_ERROR, sizeof(*errmsg), flags);
+	if (!rep)
+		goto err_bad_put;
+	errmsg = nlmsg_data(rep);
+	errmsg->error = err;
+	errmsg->msg = *nlh;
+
+	if (!(flags & NLM_F_CAPPED)) {
+		if (!nlmsg_append(skb, nlmsg_len(nlh)))
+			goto err_bad_put;
+
+		memcpy(nlmsg_data(&errmsg->msg), nlmsg_data(nlh),
+		       nlmsg_len(nlh));
+	}
+
+	if (tlvlen)
+		netlink_ack_tlv_fill(in_skb, skb, nlh, err, extack);
+
+	nlmsg_end(skb, rep);
+
+	nlmsg_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid);
+
+	return;
+
+err_bad_put:
+	nlmsg_free(skb);
+err_skb:
+	WRITE_ONCE(NETLINK_CB(in_skb).sk->sk_err, ENOBUFS);
+	sk_error_report(NETLINK_CB(in_skb).sk);
+}
+EXPORT_SYMBOL(netlink_ack);
+
+int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
+						   struct nlmsghdr *,
+						   struct netlink_ext_ack *))
+{
+	struct netlink_ext_ack extack;
+	struct nlmsghdr *nlh;
+	int err;
+
+	while (skb->len >= nlmsg_total_size(0)) {
+		int msglen;
+
+		memset(&extack, 0, sizeof(extack));
+		nlh = nlmsg_hdr(skb);
+		err = 0;
+
+		if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
+			return 0;
+
+		/* Only requests are handled by the kernel */
+		if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
+			goto ack;
+
+		/* Skip control messages */
+		if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
+			goto ack;
+
+		err = cb(skb, nlh, &extack);
+		if (err == -EINTR)
+			goto skip;
+
+ack:
+		if (nlh->nlmsg_flags & NLM_F_ACK || err)
+			netlink_ack(skb, nlh, err, &extack);
+
+skip:
+		msglen = NLMSG_ALIGN(nlh->nlmsg_len);
+		if (msglen > skb->len)
+			msglen = skb->len;
+		skb_pull(skb, msglen);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(netlink_rcv_skb);
+
+/**
+ * nlmsg_notify - send a notification netlink message
+ * @sk: netlink socket to use
+ * @skb: notification message
+ * @portid: destination netlink portid for reports or 0
+ * @group: destination multicast group or 0
+ * @report: 1 to report back, 0 to disable
+ * @flags: allocation flags
+ */
+int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
+		 unsigned int group, int report, gfp_t flags)
+{
+	int err = 0;
+
+	if (group) {
+		int exclude_portid = 0;
+
+		if (report) {
+			refcount_inc(&skb->users);
+			exclude_portid = portid;
+		}
+
+		/* errors reported via destination sk->sk_err, but propagate
+		 * delivery errors if NETLINK_BROADCAST_ERROR flag is set */
+		err = nlmsg_multicast(sk, skb, exclude_portid, group, flags);
+		if (err == -ESRCH)
+			err = 0;
+	}
+
+	if (report) {
+		int err2;
+
+		err2 = nlmsg_unicast(sk, skb, portid);
+		if (!err)
+			err = err2;
+	}
+
+	return err;
+}
+EXPORT_SYMBOL(nlmsg_notify);
+
+#ifdef CONFIG_PROC_FS
+struct nl_seq_iter {
+	struct seq_net_private p;
+	struct rhashtable_iter hti;
+	int link;
+};
+
+static void netlink_walk_start(struct nl_seq_iter *iter)
+{
+	rhashtable_walk_enter(&nl_table[iter->link].hash, &iter->hti);
+	rhashtable_walk_start(&iter->hti);
+}
+
+static void netlink_walk_stop(struct nl_seq_iter *iter)
+{
+	rhashtable_walk_stop(&iter->hti);
+	rhashtable_walk_exit(&iter->hti);
+}
+
+static void *__netlink_seq_next(struct seq_file *seq)
+{
+	struct nl_seq_iter *iter = seq->private;
+	struct netlink_sock *nlk;
+
+	do {
+		for (;;) {
+			nlk = rhashtable_walk_next(&iter->hti);
+
+			if (IS_ERR(nlk)) {
+				if (PTR_ERR(nlk) == -EAGAIN)
+					continue;
+
+				return nlk;
+			}
+
+			if (nlk)
+				break;
+
+			netlink_walk_stop(iter);
+			if (++iter->link >= MAX_LINKS)
+				return NULL;
+
+			netlink_walk_start(iter);
+		}
+	} while (sock_net(&nlk->sk) != seq_file_net(seq));
+
+	return nlk;
+}
+
+static void *netlink_seq_start(struct seq_file *seq, loff_t *posp)
+	__acquires(RCU)
+{
+	struct nl_seq_iter *iter = seq->private;
+	void *obj = SEQ_START_TOKEN;
+	loff_t pos;
+
+	iter->link = 0;
+
+	netlink_walk_start(iter);
+
+	for (pos = *posp; pos && obj && !IS_ERR(obj); pos--)
+		obj = __netlink_seq_next(seq);
+
+	return obj;
+}
+
+static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	++*pos;
+	return __netlink_seq_next(seq);
+}
+
+static void netlink_native_seq_stop(struct seq_file *seq, void *v)
+{
+	struct nl_seq_iter *iter = seq->private;
+
+	if (iter->link >= MAX_LINKS)
+		return;
+
+	netlink_walk_stop(iter);
+}
+
+
+static int netlink_native_seq_show(struct seq_file *seq, void *v)
+{
+	if (v == SEQ_START_TOKEN) {
+		seq_puts(seq,
+			 "sk               Eth Pid        Groups   "
+			 "Rmem     Wmem     Dump  Locks    Drops    Inode\n");
+	} else {
+		struct sock *s = v;
+		struct netlink_sock *nlk = nlk_sk(s);
+
+		seq_printf(seq, "%pK %-3d %-10u %08x %-8d %-8d %-5d %-8d %-8u %-8lu\n",
+			   s,
+			   s->sk_protocol,
+			   nlk->portid,
+			   nlk->groups ? (u32)nlk->groups[0] : 0,
+			   sk_rmem_alloc_get(s),
+			   sk_wmem_alloc_get(s),
+			   READ_ONCE(nlk->cb_running),
+			   refcount_read(&s->sk_refcnt),
+			   atomic_read(&s->sk_drops),
+			   sock_i_ino(s)
+			);
+
+	}
+	return 0;
+}
+
+#ifdef CONFIG_BPF_SYSCALL
+struct bpf_iter__netlink {
+	__bpf_md_ptr(struct bpf_iter_meta *, meta);
+	__bpf_md_ptr(struct netlink_sock *, sk);
+};
+
+DEFINE_BPF_ITER_FUNC(netlink, struct bpf_iter_meta *meta, struct netlink_sock *sk)
+
+static int netlink_prog_seq_show(struct bpf_prog *prog,
+				  struct bpf_iter_meta *meta,
+				  void *v)
+{
+	struct bpf_iter__netlink ctx;
+
+	meta->seq_num--;  /* skip SEQ_START_TOKEN */
+	ctx.meta = meta;
+	ctx.sk = nlk_sk((struct sock *)v);
+	return bpf_iter_run_prog(prog, &ctx);
+}
+
+static int netlink_seq_show(struct seq_file *seq, void *v)
+{
+	struct bpf_iter_meta meta;
+	struct bpf_prog *prog;
+
+	meta.seq = seq;
+	prog = bpf_iter_get_info(&meta, false);
+	if (!prog)
+		return netlink_native_seq_show(seq, v);
+
+	if (v != SEQ_START_TOKEN)
+		return netlink_prog_seq_show(prog, &meta, v);
+
+	return 0;
+}
+
+static void netlink_seq_stop(struct seq_file *seq, void *v)
+{
+	struct bpf_iter_meta meta;
+	struct bpf_prog *prog;
+
+	if (!v) {
+		meta.seq = seq;
+		prog = bpf_iter_get_info(&meta, true);
+		if (prog)
+			(void)netlink_prog_seq_show(prog, &meta, v);
+	}
+
+	netlink_native_seq_stop(seq, v);
+}
+#else
+static int netlink_seq_show(struct seq_file *seq, void *v)
+{
+	return netlink_native_seq_show(seq, v);
+}
+
+static void netlink_seq_stop(struct seq_file *seq, void *v)
+{
+	netlink_native_seq_stop(seq, v);
+}
+#endif
+
+static const struct seq_operations netlink_seq_ops = {
+	.start  = netlink_seq_start,
+	.next   = netlink_seq_next,
+	.stop   = netlink_seq_stop,
+	.show   = netlink_seq_show,
+};
+#endif
+
+int netlink_register_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&netlink_chain, nb);
+}
+EXPORT_SYMBOL(netlink_register_notifier);
+
+int netlink_unregister_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&netlink_chain, nb);
+}
+EXPORT_SYMBOL(netlink_unregister_notifier);
+
+static const struct proto_ops netlink_ops = {
+	.family =	PF_NETLINK,
+	.owner =	THIS_MODULE,
+	.release =	netlink_release,
+	.bind =		netlink_bind,
+	.connect =	netlink_connect,
+	.socketpair =	sock_no_socketpair,
+	.accept =	sock_no_accept,
+	.getname =	netlink_getname,
+	.poll =		datagram_poll,
+	.ioctl =	netlink_ioctl,
+	.listen =	sock_no_listen,
+	.shutdown =	sock_no_shutdown,
+	.setsockopt =	netlink_setsockopt,
+	.getsockopt =	netlink_getsockopt,
+	.sendmsg =	netlink_sendmsg,
+	.recvmsg =	netlink_recvmsg,
+	.mmap =		sock_no_mmap,
+	.sendpage =	sock_no_sendpage,
+};
+
+static const struct net_proto_family netlink_family_ops = {
+	.family = PF_NETLINK,
+	.create = netlink_create,
+	.owner	= THIS_MODULE,	/* for consistency 8) */
+};
+
+static int __net_init netlink_net_init(struct net *net)
+{
+#ifdef CONFIG_PROC_FS
+	if (!proc_create_net("netlink", 0, net->proc_net, &netlink_seq_ops,
+			sizeof(struct nl_seq_iter)))
+		return -ENOMEM;
+#endif
+	return 0;
+}
+
+static void __net_exit netlink_net_exit(struct net *net)
+{
+#ifdef CONFIG_PROC_FS
+	remove_proc_entry("netlink", net->proc_net);
+#endif
+}
+
+static void __init netlink_add_usersock_entry(void)
+{
+	struct listeners *listeners;
+	int groups = 32;
+
+	listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
+	if (!listeners)
+		panic("netlink_add_usersock_entry: Cannot allocate listeners\n");
+
+	netlink_table_grab();
+
+	nl_table[NETLINK_USERSOCK].groups = groups;
+	rcu_assign_pointer(nl_table[NETLINK_USERSOCK].listeners, listeners);
+	nl_table[NETLINK_USERSOCK].module = THIS_MODULE;
+	nl_table[NETLINK_USERSOCK].registered = 1;
+	nl_table[NETLINK_USERSOCK].flags = NL_CFG_F_NONROOT_SEND;
+
+	netlink_table_ungrab();
+}
+
+static struct pernet_operations __net_initdata netlink_net_ops = {
+	.init = netlink_net_init,
+	.exit = netlink_net_exit,
+};
+
+static inline u32 netlink_hash(const void *data, u32 len, u32 seed)
+{
+	const struct netlink_sock *nlk = data;
+	struct netlink_compare_arg arg;
+
+	netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->portid);
+	return jhash2((u32 *)&arg, netlink_compare_arg_len / sizeof(u32), seed);
+}
+
+static const struct rhashtable_params netlink_rhashtable_params = {
+	.head_offset = offsetof(struct netlink_sock, node),
+	.key_len = netlink_compare_arg_len,
+	.obj_hashfn = netlink_hash,
+	.obj_cmpfn = netlink_compare,
+	.automatic_shrinking = true,
+};
+
+#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+BTF_ID_LIST(btf_netlink_sock_id)
+BTF_ID(struct, netlink_sock)
+
+static const struct bpf_iter_seq_info netlink_seq_info = {
+	.seq_ops		= &netlink_seq_ops,
+	.init_seq_private	= bpf_iter_init_seq_net,
+	.fini_seq_private	= bpf_iter_fini_seq_net,
+	.seq_priv_size		= sizeof(struct nl_seq_iter),
+};
+
+static struct bpf_iter_reg netlink_reg_info = {
+	.target			= "netlink",
+	.ctx_arg_info_size	= 1,
+	.ctx_arg_info		= {
+		{ offsetof(struct bpf_iter__netlink, sk),
+		  PTR_TO_BTF_ID_OR_NULL },
+	},
+	.seq_info		= &netlink_seq_info,
+};
+
+static int __init bpf_iter_register(void)
+{
+	netlink_reg_info.ctx_arg_info[0].btf_id = *btf_netlink_sock_id;
+	return bpf_iter_reg_target(&netlink_reg_info);
+}
+#endif
+
+static int __init netlink_proto_init(void)
+{
+	int i;
+	int err = proto_register(&netlink_proto, 0);
+
+	if (err != 0)
+		goto out;
+
+#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+	err = bpf_iter_register();
+	if (err)
+		goto out;
+#endif
+
+	BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > sizeof_field(struct sk_buff, cb));
+
+	nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
+	if (!nl_table)
+		goto panic;
+
+	for (i = 0; i < MAX_LINKS; i++) {
+		if (rhashtable_init(&nl_table[i].hash,
+				    &netlink_rhashtable_params) < 0) {
+			while (--i > 0)
+				rhashtable_destroy(&nl_table[i].hash);
+			kfree(nl_table);
+			goto panic;
+		}
+	}
+
+	netlink_add_usersock_entry();
+
+	sock_register(&netlink_family_ops);
+	register_pernet_subsys(&netlink_net_ops);
+	register_pernet_subsys(&netlink_tap_net_ops);
+	/* The netlink device handler may be needed early. */
+	rtnetlink_init();
+out:
+	return err;
+panic:
+	panic("netlink_init: Cannot allocate nl_table\n");
+}
+
+core_initcall(netlink_proto_init);