Adding upstream version 6.1.76.upstream/6.1.76

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

10 files changed, 4036 insertions, 0 deletions

diff --git a/net/netrom/Makefile b/net/netrom/Makefile
new file mode 100644
index 000000000..603e36c9a
--- /dev/null
+++ b/net/netrom/Makefile
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for the Linux NET/ROM layer.
+#
+
+obj-$(CONFIG_NETROM) += netrom.o
+
+netrom-y		:= af_netrom.o nr_dev.o nr_in.o nr_loopback.o \
+			   nr_out.o nr_route.o nr_subr.o nr_timer.o
+netrom-$(CONFIG_SYSCTL)	+= sysctl_net_netrom.o
diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
new file mode 100644
index 000000000..ec5747969
--- /dev/null
+++ b/net/netrom/af_netrom.c
@@ -0,0 +1,1537 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ * Copyright Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
+ * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/sched/signal.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/stat.h>
+#include <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <linux/skbuff.h>
+#include <net/net_namespace.h>
+#include <net/sock.h>
+#include <linux/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/termios.h>	/* For TIOCINQ/OUTQ */
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/notifier.h>
+#include <net/netrom.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <net/ip.h>
+#include <net/tcp_states.h>
+#include <net/arp.h>
+#include <linux/init.h>
+
+static int nr_ndevs = 4;
+
+int sysctl_netrom_default_path_quality            = NR_DEFAULT_QUAL;
+int sysctl_netrom_obsolescence_count_initialiser  = NR_DEFAULT_OBS;
+int sysctl_netrom_network_ttl_initialiser         = NR_DEFAULT_TTL;
+int sysctl_netrom_transport_timeout               = NR_DEFAULT_T1;
+int sysctl_netrom_transport_maximum_tries         = NR_DEFAULT_N2;
+int sysctl_netrom_transport_acknowledge_delay     = NR_DEFAULT_T2;
+int sysctl_netrom_transport_busy_delay            = NR_DEFAULT_T4;
+int sysctl_netrom_transport_requested_window_size = NR_DEFAULT_WINDOW;
+int sysctl_netrom_transport_no_activity_timeout   = NR_DEFAULT_IDLE;
+int sysctl_netrom_routing_control                 = NR_DEFAULT_ROUTING;
+int sysctl_netrom_link_fails_count                = NR_DEFAULT_FAILS;
+int sysctl_netrom_reset_circuit                   = NR_DEFAULT_RESET;
+
+static unsigned short circuit = 0x101;
+
+static HLIST_HEAD(nr_list);
+static DEFINE_SPINLOCK(nr_list_lock);
+
+static const struct proto_ops nr_proto_ops;
+
+/*
+ * NETROM network devices are virtual network devices encapsulating NETROM
+ * frames into AX.25 which will be sent through an AX.25 device, so form a
+ * special "super class" of normal net devices; split their locks off into a
+ * separate class since they always nest.
+ */
+static struct lock_class_key nr_netdev_xmit_lock_key;
+static struct lock_class_key nr_netdev_addr_lock_key;
+
+static void nr_set_lockdep_one(struct net_device *dev,
+			       struct netdev_queue *txq,
+			       void *_unused)
+{
+	lockdep_set_class(&txq->_xmit_lock, &nr_netdev_xmit_lock_key);
+}
+
+static void nr_set_lockdep_key(struct net_device *dev)
+{
+	lockdep_set_class(&dev->addr_list_lock, &nr_netdev_addr_lock_key);
+	netdev_for_each_tx_queue(dev, nr_set_lockdep_one, NULL);
+}
+
+/*
+ *	Socket removal during an interrupt is now safe.
+ */
+static void nr_remove_socket(struct sock *sk)
+{
+	spin_lock_bh(&nr_list_lock);
+	sk_del_node_init(sk);
+	spin_unlock_bh(&nr_list_lock);
+}
+
+/*
+ *	Kill all bound sockets on a dropped device.
+ */
+static void nr_kill_by_device(struct net_device *dev)
+{
+	struct sock *s;
+
+	spin_lock_bh(&nr_list_lock);
+	sk_for_each(s, &nr_list)
+		if (nr_sk(s)->device == dev)
+			nr_disconnect(s, ENETUNREACH);
+	spin_unlock_bh(&nr_list_lock);
+}
+
+/*
+ *	Handle device status changes.
+ */
+static int nr_device_event(struct notifier_block *this, unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+
+	if (!net_eq(dev_net(dev), &init_net))
+		return NOTIFY_DONE;
+
+	if (event != NETDEV_DOWN)
+		return NOTIFY_DONE;
+
+	nr_kill_by_device(dev);
+	nr_rt_device_down(dev);
+
+	return NOTIFY_DONE;
+}
+
+/*
+ *	Add a socket to the bound sockets list.
+ */
+static void nr_insert_socket(struct sock *sk)
+{
+	spin_lock_bh(&nr_list_lock);
+	sk_add_node(sk, &nr_list);
+	spin_unlock_bh(&nr_list_lock);
+}
+
+/*
+ *	Find a socket that wants to accept the Connect Request we just
+ *	received.
+ */
+static struct sock *nr_find_listener(ax25_address *addr)
+{
+	struct sock *s;
+
+	spin_lock_bh(&nr_list_lock);
+	sk_for_each(s, &nr_list)
+		if (!ax25cmp(&nr_sk(s)->source_addr, addr) &&
+		    s->sk_state == TCP_LISTEN) {
+			sock_hold(s);
+			goto found;
+		}
+	s = NULL;
+found:
+	spin_unlock_bh(&nr_list_lock);
+	return s;
+}
+
+/*
+ *	Find a connected NET/ROM socket given my circuit IDs.
+ */
+static struct sock *nr_find_socket(unsigned char index, unsigned char id)
+{
+	struct sock *s;
+
+	spin_lock_bh(&nr_list_lock);
+	sk_for_each(s, &nr_list) {
+		struct nr_sock *nr = nr_sk(s);
+
+		if (nr->my_index == index && nr->my_id == id) {
+			sock_hold(s);
+			goto found;
+		}
+	}
+	s = NULL;
+found:
+	spin_unlock_bh(&nr_list_lock);
+	return s;
+}
+
+/*
+ *	Find a connected NET/ROM socket given their circuit IDs.
+ */
+static struct sock *nr_find_peer(unsigned char index, unsigned char id,
+	ax25_address *dest)
+{
+	struct sock *s;
+
+	spin_lock_bh(&nr_list_lock);
+	sk_for_each(s, &nr_list) {
+		struct nr_sock *nr = nr_sk(s);
+
+		if (nr->your_index == index && nr->your_id == id &&
+		    !ax25cmp(&nr->dest_addr, dest)) {
+			sock_hold(s);
+			goto found;
+		}
+	}
+	s = NULL;
+found:
+	spin_unlock_bh(&nr_list_lock);
+	return s;
+}
+
+/*
+ *	Find next free circuit ID.
+ */
+static unsigned short nr_find_next_circuit(void)
+{
+	unsigned short id = circuit;
+	unsigned char i, j;
+	struct sock *sk;
+
+	for (;;) {
+		i = id / 256;
+		j = id % 256;
+
+		if (i != 0 && j != 0) {
+			if ((sk=nr_find_socket(i, j)) == NULL)
+				break;
+			sock_put(sk);
+		}
+
+		id++;
+	}
+
+	return id;
+}
+
+/*
+ *	Deferred destroy.
+ */
+void nr_destroy_socket(struct sock *);
+
+/*
+ *	Handler for deferred kills.
+ */
+static void nr_destroy_timer(struct timer_list *t)
+{
+	struct sock *sk = from_timer(sk, t, sk_timer);
+	bh_lock_sock(sk);
+	sock_hold(sk);
+	nr_destroy_socket(sk);
+	bh_unlock_sock(sk);
+	sock_put(sk);
+}
+
+/*
+ *	This is called from user mode and the timers. Thus it protects itself
+ *	against interrupt users but doesn't worry about being called during
+ *	work. Once it is removed from the queue no interrupt or bottom half
+ *	will touch it and we are (fairly 8-) ) safe.
+ */
+void nr_destroy_socket(struct sock *sk)
+{
+	struct sk_buff *skb;
+
+	nr_remove_socket(sk);
+
+	nr_stop_heartbeat(sk);
+	nr_stop_t1timer(sk);
+	nr_stop_t2timer(sk);
+	nr_stop_t4timer(sk);
+	nr_stop_idletimer(sk);
+
+	nr_clear_queues(sk);		/* Flush the queues */
+
+	while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
+		if (skb->sk != sk) { /* A pending connection */
+			/* Queue the unaccepted socket for death */
+			sock_set_flag(skb->sk, SOCK_DEAD);
+			nr_start_heartbeat(skb->sk);
+			nr_sk(skb->sk)->state = NR_STATE_0;
+		}
+
+		kfree_skb(skb);
+	}
+
+	if (sk_has_allocations(sk)) {
+		/* Defer: outstanding buffers */
+		sk->sk_timer.function = nr_destroy_timer;
+		sk->sk_timer.expires  = jiffies + 2 * HZ;
+		add_timer(&sk->sk_timer);
+	} else
+		sock_put(sk);
+}
+
+/*
+ *	Handling for system calls applied via the various interfaces to a
+ *	NET/ROM socket object.
+ */
+
+static int nr_setsockopt(struct socket *sock, int level, int optname,
+		sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = sock->sk;
+	struct nr_sock *nr = nr_sk(sk);
+	unsigned int opt;
+
+	if (level != SOL_NETROM)
+		return -ENOPROTOOPT;
+
+	if (optlen < sizeof(unsigned int))
+		return -EINVAL;
+
+	if (copy_from_sockptr(&opt, optval, sizeof(opt)))
+		return -EFAULT;
+
+	switch (optname) {
+	case NETROM_T1:
+		if (opt < 1 || opt > UINT_MAX / HZ)
+			return -EINVAL;
+		nr->t1 = opt * HZ;
+		return 0;
+
+	case NETROM_T2:
+		if (opt < 1 || opt > UINT_MAX / HZ)
+			return -EINVAL;
+		nr->t2 = opt * HZ;
+		return 0;
+
+	case NETROM_N2:
+		if (opt < 1 || opt > 31)
+			return -EINVAL;
+		nr->n2 = opt;
+		return 0;
+
+	case NETROM_T4:
+		if (opt < 1 || opt > UINT_MAX / HZ)
+			return -EINVAL;
+		nr->t4 = opt * HZ;
+		return 0;
+
+	case NETROM_IDLE:
+		if (opt > UINT_MAX / (60 * HZ))
+			return -EINVAL;
+		nr->idle = opt * 60 * HZ;
+		return 0;
+
+	default:
+		return -ENOPROTOOPT;
+	}
+}
+
+static int nr_getsockopt(struct socket *sock, int level, int optname,
+	char __user *optval, int __user *optlen)
+{
+	struct sock *sk = sock->sk;
+	struct nr_sock *nr = nr_sk(sk);
+	int val = 0;
+	int len;
+
+	if (level != SOL_NETROM)
+		return -ENOPROTOOPT;
+
+	if (get_user(len, optlen))
+		return -EFAULT;
+
+	if (len < 0)
+		return -EINVAL;
+
+	switch (optname) {
+	case NETROM_T1:
+		val = nr->t1 / HZ;
+		break;
+
+	case NETROM_T2:
+		val = nr->t2 / HZ;
+		break;
+
+	case NETROM_N2:
+		val = nr->n2;
+		break;
+
+	case NETROM_T4:
+		val = nr->t4 / HZ;
+		break;
+
+	case NETROM_IDLE:
+		val = nr->idle / (60 * HZ);
+		break;
+
+	default:
+		return -ENOPROTOOPT;
+	}
+
+	len = min_t(unsigned int, len, sizeof(int));
+
+	if (put_user(len, optlen))
+		return -EFAULT;
+
+	return copy_to_user(optval, &val, len) ? -EFAULT : 0;
+}
+
+static int nr_listen(struct socket *sock, int backlog)
+{
+	struct sock *sk = sock->sk;
+
+	lock_sock(sk);
+	if (sock->state != SS_UNCONNECTED) {
+		release_sock(sk);
+		return -EINVAL;
+	}
+
+	if (sk->sk_state != TCP_LISTEN) {
+		memset(&nr_sk(sk)->user_addr, 0, AX25_ADDR_LEN);
+		sk->sk_max_ack_backlog = backlog;
+		sk->sk_state           = TCP_LISTEN;
+		release_sock(sk);
+		return 0;
+	}
+	release_sock(sk);
+
+	return -EOPNOTSUPP;
+}
+
+static struct proto nr_proto = {
+	.name	  = "NETROM",
+	.owner	  = THIS_MODULE,
+	.obj_size = sizeof(struct nr_sock),
+};
+
+static int nr_create(struct net *net, struct socket *sock, int protocol,
+		     int kern)
+{
+	struct sock *sk;
+	struct nr_sock *nr;
+
+	if (!net_eq(net, &init_net))
+		return -EAFNOSUPPORT;
+
+	if (sock->type != SOCK_SEQPACKET || protocol != 0)
+		return -ESOCKTNOSUPPORT;
+
+	sk = sk_alloc(net, PF_NETROM, GFP_ATOMIC, &nr_proto, kern);
+	if (sk  == NULL)
+		return -ENOMEM;
+
+	nr = nr_sk(sk);
+
+	sock_init_data(sock, sk);
+
+	sock->ops    = &nr_proto_ops;
+	sk->sk_protocol = protocol;
+
+	skb_queue_head_init(&nr->ack_queue);
+	skb_queue_head_init(&nr->reseq_queue);
+	skb_queue_head_init(&nr->frag_queue);
+
+	nr_init_timers(sk);
+
+	nr->t1     =
+		msecs_to_jiffies(sysctl_netrom_transport_timeout);
+	nr->t2     =
+		msecs_to_jiffies(sysctl_netrom_transport_acknowledge_delay);
+	nr->n2     =
+		msecs_to_jiffies(sysctl_netrom_transport_maximum_tries);
+	nr->t4     =
+		msecs_to_jiffies(sysctl_netrom_transport_busy_delay);
+	nr->idle   =
+		msecs_to_jiffies(sysctl_netrom_transport_no_activity_timeout);
+	nr->window = sysctl_netrom_transport_requested_window_size;
+
+	nr->bpqext = 1;
+	nr->state  = NR_STATE_0;
+
+	return 0;
+}
+
+static struct sock *nr_make_new(struct sock *osk)
+{
+	struct sock *sk;
+	struct nr_sock *nr, *onr;
+
+	if (osk->sk_type != SOCK_SEQPACKET)
+		return NULL;
+
+	sk = sk_alloc(sock_net(osk), PF_NETROM, GFP_ATOMIC, osk->sk_prot, 0);
+	if (sk == NULL)
+		return NULL;
+
+	nr = nr_sk(sk);
+
+	sock_init_data(NULL, sk);
+
+	sk->sk_type     = osk->sk_type;
+	sk->sk_priority = osk->sk_priority;
+	sk->sk_protocol = osk->sk_protocol;
+	sk->sk_rcvbuf   = osk->sk_rcvbuf;
+	sk->sk_sndbuf   = osk->sk_sndbuf;
+	sk->sk_state    = TCP_ESTABLISHED;
+	sock_copy_flags(sk, osk);
+
+	skb_queue_head_init(&nr->ack_queue);
+	skb_queue_head_init(&nr->reseq_queue);
+	skb_queue_head_init(&nr->frag_queue);
+
+	nr_init_timers(sk);
+
+	onr = nr_sk(osk);
+
+	nr->t1      = onr->t1;
+	nr->t2      = onr->t2;
+	nr->n2      = onr->n2;
+	nr->t4      = onr->t4;
+	nr->idle    = onr->idle;
+	nr->window  = onr->window;
+
+	nr->device  = onr->device;
+	nr->bpqext  = onr->bpqext;
+
+	return sk;
+}
+
+static int nr_release(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct nr_sock *nr;
+
+	if (sk == NULL) return 0;
+
+	sock_hold(sk);
+	sock_orphan(sk);
+	lock_sock(sk);
+	nr = nr_sk(sk);
+
+	switch (nr->state) {
+	case NR_STATE_0:
+	case NR_STATE_1:
+	case NR_STATE_2:
+		nr_disconnect(sk, 0);
+		nr_destroy_socket(sk);
+		break;
+
+	case NR_STATE_3:
+		nr_clear_queues(sk);
+		nr->n2count = 0;
+		nr_write_internal(sk, NR_DISCREQ);
+		nr_start_t1timer(sk);
+		nr_stop_t2timer(sk);
+		nr_stop_t4timer(sk);
+		nr_stop_idletimer(sk);
+		nr->state    = NR_STATE_2;
+		sk->sk_state    = TCP_CLOSE;
+		sk->sk_shutdown |= SEND_SHUTDOWN;
+		sk->sk_state_change(sk);
+		sock_set_flag(sk, SOCK_DESTROY);
+		break;
+
+	default:
+		break;
+	}
+
+	sock->sk   = NULL;
+	release_sock(sk);
+	sock_put(sk);
+
+	return 0;
+}
+
+static int nr_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
+{
+	struct sock *sk = sock->sk;
+	struct nr_sock *nr = nr_sk(sk);
+	struct full_sockaddr_ax25 *addr = (struct full_sockaddr_ax25 *)uaddr;
+	struct net_device *dev;
+	ax25_uid_assoc *user;
+	ax25_address *source;
+
+	lock_sock(sk);
+	if (!sock_flag(sk, SOCK_ZAPPED)) {
+		release_sock(sk);
+		return -EINVAL;
+	}
+	if (addr_len < sizeof(struct sockaddr_ax25) || addr_len > sizeof(struct full_sockaddr_ax25)) {
+		release_sock(sk);
+		return -EINVAL;
+	}
+	if (addr_len < (addr->fsa_ax25.sax25_ndigis * sizeof(ax25_address) + sizeof(struct sockaddr_ax25))) {
+		release_sock(sk);
+		return -EINVAL;
+	}
+	if (addr->fsa_ax25.sax25_family != AF_NETROM) {
+		release_sock(sk);
+		return -EINVAL;
+	}
+	if ((dev = nr_dev_get(&addr->fsa_ax25.sax25_call)) == NULL) {
+		release_sock(sk);
+		return -EADDRNOTAVAIL;
+	}
+
+	/*
+	 * Only the super user can set an arbitrary user callsign.
+	 */
+	if (addr->fsa_ax25.sax25_ndigis == 1) {
+		if (!capable(CAP_NET_BIND_SERVICE)) {
+			dev_put(dev);
+			release_sock(sk);
+			return -EPERM;
+		}
+		nr->user_addr   = addr->fsa_digipeater[0];
+		nr->source_addr = addr->fsa_ax25.sax25_call;
+	} else {
+		source = &addr->fsa_ax25.sax25_call;
+
+		user = ax25_findbyuid(current_euid());
+		if (user) {
+			nr->user_addr   = user->call;
+			ax25_uid_put(user);
+		} else {
+			if (ax25_uid_policy && !capable(CAP_NET_BIND_SERVICE)) {
+				release_sock(sk);
+				dev_put(dev);
+				return -EPERM;
+			}
+			nr->user_addr   = *source;
+		}
+
+		nr->source_addr = *source;
+	}
+
+	nr->device = dev;
+	nr_insert_socket(sk);
+
+	sock_reset_flag(sk, SOCK_ZAPPED);
+	dev_put(dev);
+	release_sock(sk);
+
+	return 0;
+}
+
+static int nr_connect(struct socket *sock, struct sockaddr *uaddr,
+	int addr_len, int flags)
+{
+	struct sock *sk = sock->sk;
+	struct nr_sock *nr = nr_sk(sk);
+	struct sockaddr_ax25 *addr = (struct sockaddr_ax25 *)uaddr;
+	const ax25_address *source = NULL;
+	ax25_uid_assoc *user;
+	struct net_device *dev;
+	int err = 0;
+
+	lock_sock(sk);
+	if (sk->sk_state == TCP_ESTABLISHED && sock->state == SS_CONNECTING) {
+		sock->state = SS_CONNECTED;
+		goto out_release;	/* Connect completed during a ERESTARTSYS event */
+	}
+
+	if (sk->sk_state == TCP_CLOSE && sock->state == SS_CONNECTING) {
+		sock->state = SS_UNCONNECTED;
+		err = -ECONNREFUSED;
+		goto out_release;
+	}
+
+	if (sk->sk_state == TCP_ESTABLISHED) {
+		err = -EISCONN;	/* No reconnect on a seqpacket socket */
+		goto out_release;
+	}
+
+	if (sock->state == SS_CONNECTING) {
+		err = -EALREADY;
+		goto out_release;
+	}
+
+	sk->sk_state   = TCP_CLOSE;
+	sock->state = SS_UNCONNECTED;
+
+	if (addr_len != sizeof(struct sockaddr_ax25) && addr_len != sizeof(struct full_sockaddr_ax25)) {
+		err = -EINVAL;
+		goto out_release;
+	}
+	if (addr->sax25_family != AF_NETROM) {
+		err = -EINVAL;
+		goto out_release;
+	}
+	if (sock_flag(sk, SOCK_ZAPPED)) {	/* Must bind first - autobinding in this may or may not work */
+		sock_reset_flag(sk, SOCK_ZAPPED);
+
+		if ((dev = nr_dev_first()) == NULL) {
+			err = -ENETUNREACH;
+			goto out_release;
+		}
+		source = (const ax25_address *)dev->dev_addr;
+
+		user = ax25_findbyuid(current_euid());
+		if (user) {
+			nr->user_addr   = user->call;
+			ax25_uid_put(user);
+		} else {
+			if (ax25_uid_policy && !capable(CAP_NET_ADMIN)) {
+				dev_put(dev);
+				err = -EPERM;
+				goto out_release;
+			}
+			nr->user_addr   = *source;
+		}
+
+		nr->source_addr = *source;
+		nr->device      = dev;
+
+		dev_put(dev);
+		nr_insert_socket(sk);		/* Finish the bind */
+	}
+
+	nr->dest_addr = addr->sax25_call;
+
+	release_sock(sk);
+	circuit = nr_find_next_circuit();
+	lock_sock(sk);
+
+	nr->my_index = circuit / 256;
+	nr->my_id    = circuit % 256;
+
+	circuit++;
+
+	/* Move to connecting socket, start sending Connect Requests */
+	sock->state  = SS_CONNECTING;
+	sk->sk_state = TCP_SYN_SENT;
+
+	nr_establish_data_link(sk);
+
+	nr->state = NR_STATE_1;
+
+	nr_start_heartbeat(sk);
+
+	/* Now the loop */
+	if (sk->sk_state != TCP_ESTABLISHED && (flags & O_NONBLOCK)) {
+		err = -EINPROGRESS;
+		goto out_release;
+	}
+
+	/*
+	 * A Connect Ack with Choke or timeout or failed routing will go to
+	 * closed.
+	 */
+	if (sk->sk_state == TCP_SYN_SENT) {
+		DEFINE_WAIT(wait);
+
+		for (;;) {
+			prepare_to_wait(sk_sleep(sk), &wait,
+					TASK_INTERRUPTIBLE);
+			if (sk->sk_state != TCP_SYN_SENT)
+				break;
+			if (!signal_pending(current)) {
+				release_sock(sk);
+				schedule();
+				lock_sock(sk);
+				continue;
+			}
+			err = -ERESTARTSYS;
+			break;
+		}
+		finish_wait(sk_sleep(sk), &wait);
+		if (err)
+			goto out_release;
+	}
+
+	if (sk->sk_state != TCP_ESTABLISHED) {
+		sock->state = SS_UNCONNECTED;
+		err = sock_error(sk);	/* Always set at this point */
+		goto out_release;
+	}
+
+	sock->state = SS_CONNECTED;
+
+out_release:
+	release_sock(sk);
+
+	return err;
+}
+
+static int nr_accept(struct socket *sock, struct socket *newsock, int flags,
+		     bool kern)
+{
+	struct sk_buff *skb;
+	struct sock *newsk;
+	DEFINE_WAIT(wait);
+	struct sock *sk;
+	int err = 0;
+
+	if ((sk = sock->sk) == NULL)
+		return -EINVAL;
+
+	lock_sock(sk);
+	if (sk->sk_type != SOCK_SEQPACKET) {
+		err = -EOPNOTSUPP;
+		goto out_release;
+	}
+
+	if (sk->sk_state != TCP_LISTEN) {
+		err = -EINVAL;
+		goto out_release;
+	}
+
+	/*
+	 *	The write queue this time is holding sockets ready to use
+	 *	hooked into the SABM we saved
+	 */
+	for (;;) {
+		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+		skb = skb_dequeue(&sk->sk_receive_queue);
+		if (skb)
+			break;
+
+		if (flags & O_NONBLOCK) {
+			err = -EWOULDBLOCK;
+			break;
+		}
+		if (!signal_pending(current)) {
+			release_sock(sk);
+			schedule();
+			lock_sock(sk);
+			continue;
+		}
+		err = -ERESTARTSYS;
+		break;
+	}
+	finish_wait(sk_sleep(sk), &wait);
+	if (err)
+		goto out_release;
+
+	newsk = skb->sk;
+	sock_graft(newsk, newsock);
+
+	/* Now attach up the new socket */
+	kfree_skb(skb);
+	sk_acceptq_removed(sk);
+
+out_release:
+	release_sock(sk);
+
+	return err;
+}
+
+static int nr_getname(struct socket *sock, struct sockaddr *uaddr,
+	int peer)
+{
+	struct full_sockaddr_ax25 *sax = (struct full_sockaddr_ax25 *)uaddr;
+	struct sock *sk = sock->sk;
+	struct nr_sock *nr = nr_sk(sk);
+	int uaddr_len;
+
+	memset(&sax->fsa_ax25, 0, sizeof(struct sockaddr_ax25));
+
+	lock_sock(sk);
+	if (peer != 0) {
+		if (sk->sk_state != TCP_ESTABLISHED) {
+			release_sock(sk);
+			return -ENOTCONN;
+		}
+		sax->fsa_ax25.sax25_family = AF_NETROM;
+		sax->fsa_ax25.sax25_ndigis = 1;
+		sax->fsa_ax25.sax25_call   = nr->user_addr;
+		memset(sax->fsa_digipeater, 0, sizeof(sax->fsa_digipeater));
+		sax->fsa_digipeater[0]     = nr->dest_addr;
+		uaddr_len = sizeof(struct full_sockaddr_ax25);
+	} else {
+		sax->fsa_ax25.sax25_family = AF_NETROM;
+		sax->fsa_ax25.sax25_ndigis = 0;
+		sax->fsa_ax25.sax25_call   = nr->source_addr;
+		uaddr_len = sizeof(struct sockaddr_ax25);
+	}
+	release_sock(sk);
+
+	return uaddr_len;
+}
+
+int nr_rx_frame(struct sk_buff *skb, struct net_device *dev)
+{
+	struct sock *sk;
+	struct sock *make;
+	struct nr_sock *nr_make;
+	ax25_address *src, *dest, *user;
+	unsigned short circuit_index, circuit_id;
+	unsigned short peer_circuit_index, peer_circuit_id;
+	unsigned short frametype, flags, window, timeout;
+	int ret;
+
+	skb_orphan(skb);
+
+	/*
+	 *	skb->data points to the netrom frame start
+	 */
+
+	src  = (ax25_address *)(skb->data + 0);
+	dest = (ax25_address *)(skb->data + 7);
+
+	circuit_index      = skb->data[15];
+	circuit_id         = skb->data[16];
+	peer_circuit_index = skb->data[17];
+	peer_circuit_id    = skb->data[18];
+	frametype          = skb->data[19] & 0x0F;
+	flags              = skb->data[19] & 0xF0;
+
+	/*
+	 * Check for an incoming IP over NET/ROM frame.
+	 */
+	if (frametype == NR_PROTOEXT &&
+	    circuit_index == NR_PROTO_IP && circuit_id == NR_PROTO_IP) {
+		skb_pull(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
+		skb_reset_transport_header(skb);
+
+		return nr_rx_ip(skb, dev);
+	}
+
+	/*
+	 * Find an existing socket connection, based on circuit ID, if it's
+	 * a Connect Request base it on their circuit ID.
+	 *
+	 * Circuit ID 0/0 is not valid but it could still be a "reset" for a
+	 * circuit that no longer exists at the other end ...
+	 */
+
+	sk = NULL;
+
+	if (circuit_index == 0 && circuit_id == 0) {
+		if (frametype == NR_CONNACK && flags == NR_CHOKE_FLAG)
+			sk = nr_find_peer(peer_circuit_index, peer_circuit_id, src);
+	} else {
+		if (frametype == NR_CONNREQ)
+			sk = nr_find_peer(circuit_index, circuit_id, src);
+		else
+			sk = nr_find_socket(circuit_index, circuit_id);
+	}
+
+	if (sk != NULL) {
+		bh_lock_sock(sk);
+		skb_reset_transport_header(skb);
+
+		if (frametype == NR_CONNACK && skb->len == 22)
+			nr_sk(sk)->bpqext = 1;
+		else
+			nr_sk(sk)->bpqext = 0;
+
+		ret = nr_process_rx_frame(sk, skb);
+		bh_unlock_sock(sk);
+		sock_put(sk);
+		return ret;
+	}
+
+	/*
+	 * Now it should be a CONNREQ.
+	 */
+	if (frametype != NR_CONNREQ) {
+		/*
+		 * Here it would be nice to be able to send a reset but
+		 * NET/ROM doesn't have one.  We've tried to extend the protocol
+		 * by sending NR_CONNACK | NR_CHOKE_FLAGS replies but that
+		 * apparently kills BPQ boxes... :-(
+		 * So now we try to follow the established behaviour of
+		 * G8PZT's Xrouter which is sending packets with command type 7
+		 * as an extension of the protocol.
+		 */
+		if (sysctl_netrom_reset_circuit &&
+		    (frametype != NR_RESET || flags != 0))
+			nr_transmit_reset(skb, 1);
+
+		return 0;
+	}
+
+	sk = nr_find_listener(dest);
+
+	user = (ax25_address *)(skb->data + 21);
+
+	if (sk == NULL || sk_acceptq_is_full(sk) ||
+	    (make = nr_make_new(sk)) == NULL) {
+		nr_transmit_refusal(skb, 0);
+		if (sk)
+			sock_put(sk);
+		return 0;
+	}
+
+	bh_lock_sock(sk);
+
+	window = skb->data[20];
+
+	sock_hold(make);
+	skb->sk             = make;
+	skb->destructor     = sock_efree;
+	make->sk_state	    = TCP_ESTABLISHED;
+
+	/* Fill in his circuit details */
+	nr_make = nr_sk(make);
+	nr_make->source_addr = *dest;
+	nr_make->dest_addr   = *src;
+	nr_make->user_addr   = *user;
+
+	nr_make->your_index  = circuit_index;
+	nr_make->your_id     = circuit_id;
+
+	bh_unlock_sock(sk);
+	circuit = nr_find_next_circuit();
+	bh_lock_sock(sk);
+
+	nr_make->my_index    = circuit / 256;
+	nr_make->my_id       = circuit % 256;
+
+	circuit++;
+
+	/* Window negotiation */
+	if (window < nr_make->window)
+		nr_make->window = window;
+
+	/* L4 timeout negotiation */
+	if (skb->len == 37) {
+		timeout = skb->data[36] * 256 + skb->data[35];
+		if (timeout * HZ < nr_make->t1)
+			nr_make->t1 = timeout * HZ;
+		nr_make->bpqext = 1;
+	} else {
+		nr_make->bpqext = 0;
+	}
+
+	nr_write_internal(make, NR_CONNACK);
+
+	nr_make->condition = 0x00;
+	nr_make->vs        = 0;
+	nr_make->va        = 0;
+	nr_make->vr        = 0;
+	nr_make->vl        = 0;
+	nr_make->state     = NR_STATE_3;
+	sk_acceptq_added(sk);
+	skb_queue_head(&sk->sk_receive_queue, skb);
+
+	if (!sock_flag(sk, SOCK_DEAD))
+		sk->sk_data_ready(sk);
+
+	bh_unlock_sock(sk);
+	sock_put(sk);
+
+	nr_insert_socket(make);
+
+	nr_start_heartbeat(make);
+	nr_start_idletimer(make);
+
+	return 1;
+}
+
+static int nr_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
+{
+	struct sock *sk = sock->sk;
+	struct nr_sock *nr = nr_sk(sk);
+	DECLARE_SOCKADDR(struct sockaddr_ax25 *, usax, msg->msg_name);
+	int err;
+	struct sockaddr_ax25 sax;
+	struct sk_buff *skb;
+	unsigned char *asmptr;
+	int size;
+
+	if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_EOR|MSG_CMSG_COMPAT))
+		return -EINVAL;
+
+	lock_sock(sk);
+	if (sock_flag(sk, SOCK_ZAPPED)) {
+		err = -EADDRNOTAVAIL;
+		goto out;
+	}
+
+	if (sk->sk_shutdown & SEND_SHUTDOWN) {
+		send_sig(SIGPIPE, current, 0);
+		err = -EPIPE;
+		goto out;
+	}
+
+	if (nr->device == NULL) {
+		err = -ENETUNREACH;
+		goto out;
+	}
+
+	if (usax) {
+		if (msg->msg_namelen < sizeof(sax)) {
+			err = -EINVAL;
+			goto out;
+		}
+		sax = *usax;
+		if (ax25cmp(&nr->dest_addr, &sax.sax25_call) != 0) {
+			err = -EISCONN;
+			goto out;
+		}
+		if (sax.sax25_family != AF_NETROM) {
+			err = -EINVAL;
+			goto out;
+		}
+	} else {
+		if (sk->sk_state != TCP_ESTABLISHED) {
+			err = -ENOTCONN;
+			goto out;
+		}
+		sax.sax25_family = AF_NETROM;
+		sax.sax25_call   = nr->dest_addr;
+	}
+
+	/* Build a packet - the conventional user limit is 236 bytes. We can
+	   do ludicrously large NetROM frames but must not overflow */
+	if (len > 65536) {
+		err = -EMSGSIZE;
+		goto out;
+	}
+
+	size = len + NR_NETWORK_LEN + NR_TRANSPORT_LEN;
+
+	if ((skb = sock_alloc_send_skb(sk, size, msg->msg_flags & MSG_DONTWAIT, &err)) == NULL)
+		goto out;
+
+	skb_reserve(skb, size - len);
+	skb_reset_transport_header(skb);
+
+	/*
+	 *	Push down the NET/ROM header
+	 */
+
+	asmptr = skb_push(skb, NR_TRANSPORT_LEN);
+
+	/* Build a NET/ROM Transport header */
+
+	*asmptr++ = nr->your_index;
+	*asmptr++ = nr->your_id;
+	*asmptr++ = 0;		/* To be filled in later */
+	*asmptr++ = 0;		/*      Ditto            */
+	*asmptr++ = NR_INFO;
+
+	/*
+	 *	Put the data on the end
+	 */
+	skb_put(skb, len);
+
+	/* User data follows immediately after the NET/ROM transport header */
+	if (memcpy_from_msg(skb_transport_header(skb), msg, len)) {
+		kfree_skb(skb);
+		err = -EFAULT;
+		goto out;
+	}
+
+	if (sk->sk_state != TCP_ESTABLISHED) {
+		kfree_skb(skb);
+		err = -ENOTCONN;
+		goto out;
+	}
+
+	nr_output(sk, skb);	/* Shove it onto the queue */
+
+	err = len;
+out:
+	release_sock(sk);
+	return err;
+}
+
+static int nr_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
+		      int flags)
+{
+	struct sock *sk = sock->sk;
+	DECLARE_SOCKADDR(struct sockaddr_ax25 *, sax, msg->msg_name);
+	size_t copied;
+	struct sk_buff *skb;
+	int er;
+
+	/*
+	 * This works for seqpacket too. The receiver has ordered the queue for
+	 * us! We do one quick check first though
+	 */
+
+	lock_sock(sk);
+	if (sk->sk_state != TCP_ESTABLISHED) {
+		release_sock(sk);
+		return -ENOTCONN;
+	}
+
+	/* Now we can treat all alike */
+	skb = skb_recv_datagram(sk, flags, &er);
+	if (!skb) {
+		release_sock(sk);
+		return er;
+	}
+
+	skb_reset_transport_header(skb);
+	copied     = skb->len;
+
+	if (copied > size) {
+		copied = size;
+		msg->msg_flags |= MSG_TRUNC;
+	}
+
+	er = skb_copy_datagram_msg(skb, 0, msg, copied);
+	if (er < 0) {
+		skb_free_datagram(sk, skb);
+		release_sock(sk);
+		return er;
+	}
+
+	if (sax != NULL) {
+		memset(sax, 0, sizeof(*sax));
+		sax->sax25_family = AF_NETROM;
+		skb_copy_from_linear_data_offset(skb, 7, sax->sax25_call.ax25_call,
+			      AX25_ADDR_LEN);
+		msg->msg_namelen = sizeof(*sax);
+	}
+
+	skb_free_datagram(sk, skb);
+
+	release_sock(sk);
+	return copied;
+}
+
+
+static int nr_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+{
+	struct sock *sk = sock->sk;
+	void __user *argp = (void __user *)arg;
+
+	switch (cmd) {
+	case TIOCOUTQ: {
+		long amount;
+
+		lock_sock(sk);
+		amount = sk->sk_sndbuf - sk_wmem_alloc_get(sk);
+		if (amount < 0)
+			amount = 0;
+		release_sock(sk);
+		return put_user(amount, (int __user *)argp);
+	}
+
+	case TIOCINQ: {
+		struct sk_buff *skb;
+		long amount = 0L;
+
+		lock_sock(sk);
+		/* These two are safe on a single CPU system as only user tasks fiddle here */
+		if ((skb = skb_peek(&sk->sk_receive_queue)) != NULL)
+			amount = skb->len;
+		release_sock(sk);
+		return put_user(amount, (int __user *)argp);
+	}
+
+	case SIOCGIFADDR:
+	case SIOCSIFADDR:
+	case SIOCGIFDSTADDR:
+	case SIOCSIFDSTADDR:
+	case SIOCGIFBRDADDR:
+	case SIOCSIFBRDADDR:
+	case SIOCGIFNETMASK:
+	case SIOCSIFNETMASK:
+	case SIOCGIFMETRIC:
+	case SIOCSIFMETRIC:
+		return -EINVAL;
+
+	case SIOCADDRT:
+	case SIOCDELRT:
+	case SIOCNRDECOBS:
+		if (!capable(CAP_NET_ADMIN))
+			return -EPERM;
+		return nr_rt_ioctl(cmd, argp);
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_PROC_FS
+
+static void *nr_info_start(struct seq_file *seq, loff_t *pos)
+	__acquires(&nr_list_lock)
+{
+	spin_lock_bh(&nr_list_lock);
+	return seq_hlist_start_head(&nr_list, *pos);
+}
+
+static void *nr_info_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	return seq_hlist_next(v, &nr_list, pos);
+}
+
+static void nr_info_stop(struct seq_file *seq, void *v)
+	__releases(&nr_list_lock)
+{
+	spin_unlock_bh(&nr_list_lock);
+}
+
+static int nr_info_show(struct seq_file *seq, void *v)
+{
+	struct sock *s = sk_entry(v);
+	struct net_device *dev;
+	struct nr_sock *nr;
+	const char *devname;
+	char buf[11];
+
+	if (v == SEQ_START_TOKEN)
+		seq_puts(seq,
+"user_addr dest_node src_node  dev    my  your  st  vs  vr  va    t1     t2     t4      idle   n2  wnd Snd-Q Rcv-Q inode\n");
+
+	else {
+
+		bh_lock_sock(s);
+		nr = nr_sk(s);
+
+		if ((dev = nr->device) == NULL)
+			devname = "???";
+		else
+			devname = dev->name;
+
+		seq_printf(seq, "%-9s ", ax2asc(buf, &nr->user_addr));
+		seq_printf(seq, "%-9s ", ax2asc(buf, &nr->dest_addr));
+		seq_printf(seq,
+"%-9s %-3s  %02X/%02X %02X/%02X %2d %3d %3d %3d %3lu/%03lu %2lu/%02lu %3lu/%03lu %3lu/%03lu %2d/%02d %3d %5d %5d %ld\n",
+			ax2asc(buf, &nr->source_addr),
+			devname,
+			nr->my_index,
+			nr->my_id,
+			nr->your_index,
+			nr->your_id,
+			nr->state,
+			nr->vs,
+			nr->vr,
+			nr->va,
+			ax25_display_timer(&nr->t1timer) / HZ,
+			nr->t1 / HZ,
+			ax25_display_timer(&nr->t2timer) / HZ,
+			nr->t2 / HZ,
+			ax25_display_timer(&nr->t4timer) / HZ,
+			nr->t4 / HZ,
+			ax25_display_timer(&nr->idletimer) / (60 * HZ),
+			nr->idle / (60 * HZ),
+			nr->n2count,
+			nr->n2,
+			nr->window,
+			sk_wmem_alloc_get(s),
+			sk_rmem_alloc_get(s),
+			s->sk_socket ? SOCK_INODE(s->sk_socket)->i_ino : 0L);
+
+		bh_unlock_sock(s);
+	}
+	return 0;
+}
+
+static const struct seq_operations nr_info_seqops = {
+	.start = nr_info_start,
+	.next = nr_info_next,
+	.stop = nr_info_stop,
+	.show = nr_info_show,
+};
+#endif	/* CONFIG_PROC_FS */
+
+static const struct net_proto_family nr_family_ops = {
+	.family		=	PF_NETROM,
+	.create		=	nr_create,
+	.owner		=	THIS_MODULE,
+};
+
+static const struct proto_ops nr_proto_ops = {
+	.family		=	PF_NETROM,
+	.owner		=	THIS_MODULE,
+	.release	=	nr_release,
+	.bind		=	nr_bind,
+	.connect	=	nr_connect,
+	.socketpair	=	sock_no_socketpair,
+	.accept		=	nr_accept,
+	.getname	=	nr_getname,
+	.poll		=	datagram_poll,
+	.ioctl		=	nr_ioctl,
+	.gettstamp	=	sock_gettstamp,
+	.listen		=	nr_listen,
+	.shutdown	=	sock_no_shutdown,
+	.setsockopt	=	nr_setsockopt,
+	.getsockopt	=	nr_getsockopt,
+	.sendmsg	=	nr_sendmsg,
+	.recvmsg	=	nr_recvmsg,
+	.mmap		=	sock_no_mmap,
+	.sendpage	=	sock_no_sendpage,
+};
+
+static struct notifier_block nr_dev_notifier = {
+	.notifier_call	=	nr_device_event,
+};
+
+static struct net_device **dev_nr;
+
+static struct ax25_protocol nr_pid = {
+	.pid	= AX25_P_NETROM,
+	.func	= nr_route_frame
+};
+
+static struct ax25_linkfail nr_linkfail_notifier = {
+	.func	= nr_link_failed,
+};
+
+static int __init nr_proto_init(void)
+{
+	int i;
+	int rc = proto_register(&nr_proto, 0);
+
+	if (rc)
+		return rc;
+
+	if (nr_ndevs > 0x7fffffff/sizeof(struct net_device *)) {
+		pr_err("NET/ROM: %s - nr_ndevs parameter too large\n",
+		       __func__);
+		rc = -EINVAL;
+		goto unregister_proto;
+	}
+
+	dev_nr = kcalloc(nr_ndevs, sizeof(struct net_device *), GFP_KERNEL);
+	if (!dev_nr) {
+		pr_err("NET/ROM: %s - unable to allocate device array\n",
+		       __func__);
+		rc = -ENOMEM;
+		goto unregister_proto;
+	}
+
+	for (i = 0; i < nr_ndevs; i++) {
+		char name[IFNAMSIZ];
+		struct net_device *dev;
+
+		sprintf(name, "nr%d", i);
+		dev = alloc_netdev(0, name, NET_NAME_UNKNOWN, nr_setup);
+		if (!dev) {
+			rc = -ENOMEM;
+			goto fail;
+		}
+
+		dev->base_addr = i;
+		rc = register_netdev(dev);
+		if (rc) {
+			free_netdev(dev);
+			goto fail;
+		}
+		nr_set_lockdep_key(dev);
+		dev_nr[i] = dev;
+	}
+
+	rc = sock_register(&nr_family_ops);
+	if (rc)
+		goto fail;
+
+	rc = register_netdevice_notifier(&nr_dev_notifier);
+	if (rc)
+		goto out_sock;
+
+	ax25_register_pid(&nr_pid);
+	ax25_linkfail_register(&nr_linkfail_notifier);
+
+#ifdef CONFIG_SYSCTL
+	rc = nr_register_sysctl();
+	if (rc)
+		goto out_sysctl;
+#endif
+
+	nr_loopback_init();
+
+	rc = -ENOMEM;
+	if (!proc_create_seq("nr", 0444, init_net.proc_net, &nr_info_seqops))
+		goto proc_remove1;
+	if (!proc_create_seq("nr_neigh", 0444, init_net.proc_net,
+			     &nr_neigh_seqops))
+		goto proc_remove2;
+	if (!proc_create_seq("nr_nodes", 0444, init_net.proc_net,
+			     &nr_node_seqops))
+		goto proc_remove3;
+
+	return 0;
+
+proc_remove3:
+	remove_proc_entry("nr_neigh", init_net.proc_net);
+proc_remove2:
+	remove_proc_entry("nr", init_net.proc_net);
+proc_remove1:
+
+	nr_loopback_clear();
+	nr_rt_free();
+
+#ifdef CONFIG_SYSCTL
+	nr_unregister_sysctl();
+out_sysctl:
+#endif
+	ax25_linkfail_release(&nr_linkfail_notifier);
+	ax25_protocol_release(AX25_P_NETROM);
+	unregister_netdevice_notifier(&nr_dev_notifier);
+out_sock:
+	sock_unregister(PF_NETROM);
+fail:
+	while (--i >= 0) {
+		unregister_netdev(dev_nr[i]);
+		free_netdev(dev_nr[i]);
+	}
+	kfree(dev_nr);
+unregister_proto:
+	proto_unregister(&nr_proto);
+	return rc;
+}
+
+module_init(nr_proto_init);
+
+module_param(nr_ndevs, int, 0);
+MODULE_PARM_DESC(nr_ndevs, "number of NET/ROM devices");
+
+MODULE_AUTHOR("Jonathan Naylor G4KLX <g4klx@g4klx.demon.co.uk>");
+MODULE_DESCRIPTION("The amateur radio NET/ROM network and transport layer protocol");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NETPROTO(PF_NETROM);
+
+static void __exit nr_exit(void)
+{
+	int i;
+
+	remove_proc_entry("nr", init_net.proc_net);
+	remove_proc_entry("nr_neigh", init_net.proc_net);
+	remove_proc_entry("nr_nodes", init_net.proc_net);
+	nr_loopback_clear();
+
+	nr_rt_free();
+
+#ifdef CONFIG_SYSCTL
+	nr_unregister_sysctl();
+#endif
+
+	ax25_linkfail_release(&nr_linkfail_notifier);
+	ax25_protocol_release(AX25_P_NETROM);
+
+	unregister_netdevice_notifier(&nr_dev_notifier);
+
+	sock_unregister(PF_NETROM);
+
+	for (i = 0; i < nr_ndevs; i++) {
+		struct net_device *dev = dev_nr[i];
+		if (dev) {
+			unregister_netdev(dev);
+			free_netdev(dev);
+		}
+	}
+
+	kfree(dev_nr);
+	proto_unregister(&nr_proto);
+}
+module_exit(nr_exit);
diff --git a/net/netrom/nr_dev.c b/net/netrom/nr_dev.c
new file mode 100644
index 000000000..3aaac4a22
--- /dev/null
+++ b/net/netrom/nr_dev.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ */
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/sysctl.h>
+#include <linux/string.h>
+#include <linux/socket.h>
+#include <linux/errno.h>
+#include <linux/fcntl.h>
+#include <linux/in.h>
+#include <linux/if_ether.h>	/* For the statistics structure. */
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#include <asm/io.h>
+
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/if_arp.h>
+#include <linux/skbuff.h>
+
+#include <net/ip.h>
+#include <net/arp.h>
+
+#include <net/ax25.h>
+#include <net/netrom.h>
+
+/*
+ *	Only allow IP over NET/ROM frames through if the netrom device is up.
+ */
+
+int nr_rx_ip(struct sk_buff *skb, struct net_device *dev)
+{
+	struct net_device_stats *stats = &dev->stats;
+
+	if (!netif_running(dev)) {
+		stats->rx_dropped++;
+		return 0;
+	}
+
+	stats->rx_packets++;
+	stats->rx_bytes += skb->len;
+
+	skb->protocol = htons(ETH_P_IP);
+
+	/* Spoof incoming device */
+	skb->dev      = dev;
+	skb->mac_header = skb->network_header;
+	skb_reset_network_header(skb);
+	skb->pkt_type = PACKET_HOST;
+
+	netif_rx(skb);
+
+	return 1;
+}
+
+static int nr_header(struct sk_buff *skb, struct net_device *dev,
+		     unsigned short type,
+		     const void *daddr, const void *saddr, unsigned int len)
+{
+	unsigned char *buff = skb_push(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
+
+	memcpy(buff, (saddr != NULL) ? saddr : dev->dev_addr, dev->addr_len);
+	buff[6] &= ~AX25_CBIT;
+	buff[6] &= ~AX25_EBIT;
+	buff[6] |= AX25_SSSID_SPARE;
+	buff    += AX25_ADDR_LEN;
+
+	if (daddr != NULL)
+		memcpy(buff, daddr, dev->addr_len);
+	buff[6] &= ~AX25_CBIT;
+	buff[6] |= AX25_EBIT;
+	buff[6] |= AX25_SSSID_SPARE;
+	buff    += AX25_ADDR_LEN;
+
+	*buff++ = sysctl_netrom_network_ttl_initialiser;
+
+	*buff++ = NR_PROTO_IP;
+	*buff++ = NR_PROTO_IP;
+	*buff++ = 0;
+	*buff++ = 0;
+	*buff++ = NR_PROTOEXT;
+
+	if (daddr != NULL)
+		return 37;
+
+	return -37;
+}
+
+static int __must_check nr_set_mac_address(struct net_device *dev, void *addr)
+{
+	struct sockaddr *sa = addr;
+	int err;
+
+	if (!memcmp(dev->dev_addr, sa->sa_data, dev->addr_len))
+		return 0;
+
+	if (dev->flags & IFF_UP) {
+		err = ax25_listen_register((ax25_address *)sa->sa_data, NULL);
+		if (err)
+			return err;
+
+		ax25_listen_release((const ax25_address *)dev->dev_addr, NULL);
+	}
+
+	dev_addr_set(dev, sa->sa_data);
+
+	return 0;
+}
+
+static int nr_open(struct net_device *dev)
+{
+	int err;
+
+	err = ax25_listen_register((const ax25_address *)dev->dev_addr, NULL);
+	if (err)
+		return err;
+
+	netif_start_queue(dev);
+
+	return 0;
+}
+
+static int nr_close(struct net_device *dev)
+{
+	ax25_listen_release((const ax25_address *)dev->dev_addr, NULL);
+	netif_stop_queue(dev);
+	return 0;
+}
+
+static netdev_tx_t nr_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct net_device_stats *stats = &dev->stats;
+	unsigned int len = skb->len;
+
+	if (!nr_route_frame(skb, NULL)) {
+		kfree_skb(skb);
+		stats->tx_errors++;
+		return NETDEV_TX_OK;
+	}
+
+	stats->tx_packets++;
+	stats->tx_bytes += len;
+
+	return NETDEV_TX_OK;
+}
+
+static const struct header_ops nr_header_ops = {
+	.create	= nr_header,
+};
+
+static const struct net_device_ops nr_netdev_ops = {
+	.ndo_open		= nr_open,
+	.ndo_stop		= nr_close,
+	.ndo_start_xmit		= nr_xmit,
+	.ndo_set_mac_address    = nr_set_mac_address,
+};
+
+void nr_setup(struct net_device *dev)
+{
+	dev->mtu		= NR_MAX_PACKET_SIZE;
+	dev->netdev_ops		= &nr_netdev_ops;
+	dev->header_ops		= &nr_header_ops;
+	dev->hard_header_len	= NR_NETWORK_LEN + NR_TRANSPORT_LEN;
+	dev->addr_len		= AX25_ADDR_LEN;
+	dev->type		= ARPHRD_NETROM;
+
+	/* New-style flags. */
+	dev->flags		= IFF_NOARP;
+}
diff --git a/net/netrom/nr_in.c b/net/netrom/nr_in.c
new file mode 100644
index 000000000..2f084b6f6
--- /dev/null
+++ b/net/netrom/nr_in.c
@@ -0,0 +1,301 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
+ */
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/slab.h>
+#include <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <linux/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/netrom.h>
+
+static int nr_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
+{
+	struct sk_buff *skbo, *skbn = skb;
+	struct nr_sock *nr = nr_sk(sk);
+
+	skb_pull(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
+
+	nr_start_idletimer(sk);
+
+	if (more) {
+		nr->fraglen += skb->len;
+		skb_queue_tail(&nr->frag_queue, skb);
+		return 0;
+	}
+
+	if (!more && nr->fraglen > 0) {	/* End of fragment */
+		nr->fraglen += skb->len;
+		skb_queue_tail(&nr->frag_queue, skb);
+
+		if ((skbn = alloc_skb(nr->fraglen, GFP_ATOMIC)) == NULL)
+			return 1;
+
+		skb_reset_transport_header(skbn);
+
+		while ((skbo = skb_dequeue(&nr->frag_queue)) != NULL) {
+			skb_copy_from_linear_data(skbo,
+						  skb_put(skbn, skbo->len),
+						  skbo->len);
+			kfree_skb(skbo);
+		}
+
+		nr->fraglen = 0;
+	}
+
+	return sock_queue_rcv_skb(sk, skbn);
+}
+
+/*
+ * State machine for state 1, Awaiting Connection State.
+ * The handling of the timer(s) is in file nr_timer.c.
+ * Handling of state 0 and connection release is in netrom.c.
+ */
+static int nr_state1_machine(struct sock *sk, struct sk_buff *skb,
+	int frametype)
+{
+	switch (frametype) {
+	case NR_CONNACK: {
+		struct nr_sock *nr = nr_sk(sk);
+
+		nr_stop_t1timer(sk);
+		nr_start_idletimer(sk);
+		nr->your_index = skb->data[17];
+		nr->your_id    = skb->data[18];
+		nr->vs	       = 0;
+		nr->va	       = 0;
+		nr->vr	       = 0;
+		nr->vl	       = 0;
+		nr->state      = NR_STATE_3;
+		nr->n2count    = 0;
+		nr->window     = skb->data[20];
+		sk->sk_state   = TCP_ESTABLISHED;
+		if (!sock_flag(sk, SOCK_DEAD))
+			sk->sk_state_change(sk);
+		break;
+	}
+
+	case NR_CONNACK | NR_CHOKE_FLAG:
+		nr_disconnect(sk, ECONNREFUSED);
+		break;
+
+	case NR_RESET:
+		if (sysctl_netrom_reset_circuit)
+			nr_disconnect(sk, ECONNRESET);
+		break;
+
+	default:
+		break;
+	}
+	return 0;
+}
+
+/*
+ * State machine for state 2, Awaiting Release State.
+ * The handling of the timer(s) is in file nr_timer.c
+ * Handling of state 0 and connection release is in netrom.c.
+ */
+static int nr_state2_machine(struct sock *sk, struct sk_buff *skb,
+	int frametype)
+{
+	switch (frametype) {
+	case NR_CONNACK | NR_CHOKE_FLAG:
+		nr_disconnect(sk, ECONNRESET);
+		break;
+
+	case NR_DISCREQ:
+		nr_write_internal(sk, NR_DISCACK);
+		fallthrough;
+	case NR_DISCACK:
+		nr_disconnect(sk, 0);
+		break;
+
+	case NR_RESET:
+		if (sysctl_netrom_reset_circuit)
+			nr_disconnect(sk, ECONNRESET);
+		break;
+
+	default:
+		break;
+	}
+	return 0;
+}
+
+/*
+ * State machine for state 3, Connected State.
+ * The handling of the timer(s) is in file nr_timer.c
+ * Handling of state 0 and connection release is in netrom.c.
+ */
+static int nr_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype)
+{
+	struct nr_sock *nrom = nr_sk(sk);
+	struct sk_buff_head temp_queue;
+	struct sk_buff *skbn;
+	unsigned short save_vr;
+	unsigned short nr, ns;
+	int queued = 0;
+
+	nr = skb->data[18];
+
+	switch (frametype) {
+	case NR_CONNREQ:
+		nr_write_internal(sk, NR_CONNACK);
+		break;
+
+	case NR_DISCREQ:
+		nr_write_internal(sk, NR_DISCACK);
+		nr_disconnect(sk, 0);
+		break;
+
+	case NR_CONNACK | NR_CHOKE_FLAG:
+	case NR_DISCACK:
+		nr_disconnect(sk, ECONNRESET);
+		break;
+
+	case NR_INFOACK:
+	case NR_INFOACK | NR_CHOKE_FLAG:
+	case NR_INFOACK | NR_NAK_FLAG:
+	case NR_INFOACK | NR_NAK_FLAG | NR_CHOKE_FLAG:
+		if (frametype & NR_CHOKE_FLAG) {
+			nrom->condition |= NR_COND_PEER_RX_BUSY;
+			nr_start_t4timer(sk);
+		} else {
+			nrom->condition &= ~NR_COND_PEER_RX_BUSY;
+			nr_stop_t4timer(sk);
+		}
+		if (!nr_validate_nr(sk, nr)) {
+			break;
+		}
+		if (frametype & NR_NAK_FLAG) {
+			nr_frames_acked(sk, nr);
+			nr_send_nak_frame(sk);
+		} else {
+			if (nrom->condition & NR_COND_PEER_RX_BUSY) {
+				nr_frames_acked(sk, nr);
+			} else {
+				nr_check_iframes_acked(sk, nr);
+			}
+		}
+		break;
+
+	case NR_INFO:
+	case NR_INFO | NR_NAK_FLAG:
+	case NR_INFO | NR_CHOKE_FLAG:
+	case NR_INFO | NR_MORE_FLAG:
+	case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG:
+	case NR_INFO | NR_CHOKE_FLAG | NR_MORE_FLAG:
+	case NR_INFO | NR_NAK_FLAG | NR_MORE_FLAG:
+	case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG | NR_MORE_FLAG:
+		if (frametype & NR_CHOKE_FLAG) {
+			nrom->condition |= NR_COND_PEER_RX_BUSY;
+			nr_start_t4timer(sk);
+		} else {
+			nrom->condition &= ~NR_COND_PEER_RX_BUSY;
+			nr_stop_t4timer(sk);
+		}
+		if (nr_validate_nr(sk, nr)) {
+			if (frametype & NR_NAK_FLAG) {
+				nr_frames_acked(sk, nr);
+				nr_send_nak_frame(sk);
+			} else {
+				if (nrom->condition & NR_COND_PEER_RX_BUSY) {
+					nr_frames_acked(sk, nr);
+				} else {
+					nr_check_iframes_acked(sk, nr);
+				}
+			}
+		}
+		queued = 1;
+		skb_queue_head(&nrom->reseq_queue, skb);
+		if (nrom->condition & NR_COND_OWN_RX_BUSY)
+			break;
+		skb_queue_head_init(&temp_queue);
+		do {
+			save_vr = nrom->vr;
+			while ((skbn = skb_dequeue(&nrom->reseq_queue)) != NULL) {
+				ns = skbn->data[17];
+				if (ns == nrom->vr) {
+					if (nr_queue_rx_frame(sk, skbn, frametype & NR_MORE_FLAG) == 0) {
+						nrom->vr = (nrom->vr + 1) % NR_MODULUS;
+					} else {
+						nrom->condition |= NR_COND_OWN_RX_BUSY;
+						skb_queue_tail(&temp_queue, skbn);
+					}
+				} else if (nr_in_rx_window(sk, ns)) {
+					skb_queue_tail(&temp_queue, skbn);
+				} else {
+					kfree_skb(skbn);
+				}
+			}
+			while ((skbn = skb_dequeue(&temp_queue)) != NULL) {
+				skb_queue_tail(&nrom->reseq_queue, skbn);
+			}
+		} while (save_vr != nrom->vr);
+		/*
+		 * Window is full, ack it immediately.
+		 */
+		if (((nrom->vl + nrom->window) % NR_MODULUS) == nrom->vr) {
+			nr_enquiry_response(sk);
+		} else {
+			if (!(nrom->condition & NR_COND_ACK_PENDING)) {
+				nrom->condition |= NR_COND_ACK_PENDING;
+				nr_start_t2timer(sk);
+			}
+		}
+		break;
+
+	case NR_RESET:
+		if (sysctl_netrom_reset_circuit)
+			nr_disconnect(sk, ECONNRESET);
+		break;
+
+	default:
+		break;
+	}
+	return queued;
+}
+
+/* Higher level upcall for a LAPB frame - called with sk locked */
+int nr_process_rx_frame(struct sock *sk, struct sk_buff *skb)
+{
+	struct nr_sock *nr = nr_sk(sk);
+	int queued = 0, frametype;
+
+	if (nr->state == NR_STATE_0)
+		return 0;
+
+	frametype = skb->data[19];
+
+	switch (nr->state) {
+	case NR_STATE_1:
+		queued = nr_state1_machine(sk, skb, frametype);
+		break;
+	case NR_STATE_2:
+		queued = nr_state2_machine(sk, skb, frametype);
+		break;
+	case NR_STATE_3:
+		queued = nr_state3_machine(sk, skb, frametype);
+		break;
+	}
+
+	nr_kick(sk);
+
+	return queued;
+}
diff --git a/net/netrom/nr_loopback.c b/net/netrom/nr_loopback.c
new file mode 100644
index 000000000..511819fbf
--- /dev/null
+++ b/net/netrom/nr_loopback.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright Tomi Manninen OH2BNS (oh2bns@sral.fi)
+ */
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/socket.h>
+#include <linux/timer.h>
+#include <net/ax25.h>
+#include <linux/skbuff.h>
+#include <net/netrom.h>
+#include <linux/init.h>
+
+static void nr_loopback_timer(struct timer_list *);
+
+static struct sk_buff_head loopback_queue;
+static DEFINE_TIMER(loopback_timer, nr_loopback_timer);
+
+void __init nr_loopback_init(void)
+{
+	skb_queue_head_init(&loopback_queue);
+}
+
+static inline int nr_loopback_running(void)
+{
+	return timer_pending(&loopback_timer);
+}
+
+int nr_loopback_queue(struct sk_buff *skb)
+{
+	struct sk_buff *skbn;
+
+	if ((skbn = alloc_skb(skb->len, GFP_ATOMIC)) != NULL) {
+		skb_copy_from_linear_data(skb, skb_put(skbn, skb->len), skb->len);
+		skb_reset_transport_header(skbn);
+
+		skb_queue_tail(&loopback_queue, skbn);
+
+		if (!nr_loopback_running())
+			mod_timer(&loopback_timer, jiffies + 10);
+	}
+
+	kfree_skb(skb);
+	return 1;
+}
+
+static void nr_loopback_timer(struct timer_list *unused)
+{
+	struct sk_buff *skb;
+	ax25_address *nr_dest;
+	struct net_device *dev;
+
+	if ((skb = skb_dequeue(&loopback_queue)) != NULL) {
+		nr_dest = (ax25_address *)(skb->data + 7);
+
+		dev = nr_dev_get(nr_dest);
+
+		if (dev == NULL || nr_rx_frame(skb, dev) == 0)
+			kfree_skb(skb);
+
+		dev_put(dev);
+
+		if (!skb_queue_empty(&loopback_queue) && !nr_loopback_running())
+			mod_timer(&loopback_timer, jiffies + 10);
+	}
+}
+
+void nr_loopback_clear(void)
+{
+	del_timer_sync(&loopback_timer);
+	skb_queue_purge(&loopback_queue);
+}
diff --git a/net/netrom/nr_out.c b/net/netrom/nr_out.c
new file mode 100644
index 000000000..44929657f
--- /dev/null
+++ b/net/netrom/nr_out.c
@@ -0,0 +1,270 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
+ */
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/slab.h>
+#include <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <linux/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/netrom.h>
+
+/*
+ *	This is where all NET/ROM frames pass, except for IP-over-NET/ROM which
+ *	cannot be fragmented in this manner.
+ */
+void nr_output(struct sock *sk, struct sk_buff *skb)
+{
+	struct sk_buff *skbn;
+	unsigned char transport[NR_TRANSPORT_LEN];
+	int err, frontlen, len;
+
+	if (skb->len - NR_TRANSPORT_LEN > NR_MAX_PACKET_SIZE) {
+		/* Save a copy of the Transport Header */
+		skb_copy_from_linear_data(skb, transport, NR_TRANSPORT_LEN);
+		skb_pull(skb, NR_TRANSPORT_LEN);
+
+		frontlen = skb_headroom(skb);
+
+		while (skb->len > 0) {
+			if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL)
+				return;
+
+			skb_reserve(skbn, frontlen);
+
+			len = (NR_MAX_PACKET_SIZE > skb->len) ? skb->len : NR_MAX_PACKET_SIZE;
+
+			/* Copy the user data */
+			skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
+			skb_pull(skb, len);
+
+			/* Duplicate the Transport Header */
+			skb_push(skbn, NR_TRANSPORT_LEN);
+			skb_copy_to_linear_data(skbn, transport,
+						NR_TRANSPORT_LEN);
+			if (skb->len > 0)
+				skbn->data[4] |= NR_MORE_FLAG;
+
+			skb_queue_tail(&sk->sk_write_queue, skbn); /* Throw it on the queue */
+		}
+
+		kfree_skb(skb);
+	} else {
+		skb_queue_tail(&sk->sk_write_queue, skb);		/* Throw it on the queue */
+	}
+
+	nr_kick(sk);
+}
+
+/*
+ *	This procedure is passed a buffer descriptor for an iframe. It builds
+ *	the rest of the control part of the frame and then writes it out.
+ */
+static void nr_send_iframe(struct sock *sk, struct sk_buff *skb)
+{
+	struct nr_sock *nr = nr_sk(sk);
+
+	if (skb == NULL)
+		return;
+
+	skb->data[2] = nr->vs;
+	skb->data[3] = nr->vr;
+
+	if (nr->condition & NR_COND_OWN_RX_BUSY)
+		skb->data[4] |= NR_CHOKE_FLAG;
+
+	nr_start_idletimer(sk);
+
+	nr_transmit_buffer(sk, skb);
+}
+
+void nr_send_nak_frame(struct sock *sk)
+{
+	struct sk_buff *skb, *skbn;
+	struct nr_sock *nr = nr_sk(sk);
+
+	if ((skb = skb_peek(&nr->ack_queue)) == NULL)
+		return;
+
+	if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL)
+		return;
+
+	skbn->data[2] = nr->va;
+	skbn->data[3] = nr->vr;
+
+	if (nr->condition & NR_COND_OWN_RX_BUSY)
+		skbn->data[4] |= NR_CHOKE_FLAG;
+
+	nr_transmit_buffer(sk, skbn);
+
+	nr->condition &= ~NR_COND_ACK_PENDING;
+	nr->vl         = nr->vr;
+
+	nr_stop_t1timer(sk);
+}
+
+void nr_kick(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+	struct sk_buff *skb, *skbn;
+	unsigned short start, end;
+
+	if (nr->state != NR_STATE_3)
+		return;
+
+	if (nr->condition & NR_COND_PEER_RX_BUSY)
+		return;
+
+	if (!skb_peek(&sk->sk_write_queue))
+		return;
+
+	start = (skb_peek(&nr->ack_queue) == NULL) ? nr->va : nr->vs;
+	end   = (nr->va + nr->window) % NR_MODULUS;
+
+	if (start == end)
+		return;
+
+	nr->vs = start;
+
+	/*
+	 * Transmit data until either we're out of data to send or
+	 * the window is full.
+	 */
+
+	/*
+	 * Dequeue the frame and copy it.
+	 */
+	skb = skb_dequeue(&sk->sk_write_queue);
+
+	do {
+		if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
+			skb_queue_head(&sk->sk_write_queue, skb);
+			break;
+		}
+
+		skb_set_owner_w(skbn, sk);
+
+		/*
+		 * Transmit the frame copy.
+		 */
+		nr_send_iframe(sk, skbn);
+
+		nr->vs = (nr->vs + 1) % NR_MODULUS;
+
+		/*
+		 * Requeue the original data frame.
+		 */
+		skb_queue_tail(&nr->ack_queue, skb);
+
+	} while (nr->vs != end &&
+		 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
+
+	nr->vl         = nr->vr;
+	nr->condition &= ~NR_COND_ACK_PENDING;
+
+	if (!nr_t1timer_running(sk))
+		nr_start_t1timer(sk);
+}
+
+void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb)
+{
+	struct nr_sock *nr = nr_sk(sk);
+	unsigned char *dptr;
+
+	/*
+	 *	Add the protocol byte and network header.
+	 */
+	dptr = skb_push(skb, NR_NETWORK_LEN);
+
+	memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
+	dptr[6] &= ~AX25_CBIT;
+	dptr[6] &= ~AX25_EBIT;
+	dptr[6] |= AX25_SSSID_SPARE;
+	dptr += AX25_ADDR_LEN;
+
+	memcpy(dptr, &nr->dest_addr, AX25_ADDR_LEN);
+	dptr[6] &= ~AX25_CBIT;
+	dptr[6] |= AX25_EBIT;
+	dptr[6] |= AX25_SSSID_SPARE;
+	dptr += AX25_ADDR_LEN;
+
+	*dptr++ = sysctl_netrom_network_ttl_initialiser;
+
+	if (!nr_route_frame(skb, NULL)) {
+		kfree_skb(skb);
+		nr_disconnect(sk, ENETUNREACH);
+	}
+}
+
+/*
+ * The following routines are taken from page 170 of the 7th ARRL Computer
+ * Networking Conference paper, as is the whole state machine.
+ */
+
+void nr_establish_data_link(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+
+	nr->condition = 0x00;
+	nr->n2count   = 0;
+
+	nr_write_internal(sk, NR_CONNREQ);
+
+	nr_stop_t2timer(sk);
+	nr_stop_t4timer(sk);
+	nr_stop_idletimer(sk);
+	nr_start_t1timer(sk);
+}
+
+/*
+ * Never send a NAK when we are CHOKEd.
+ */
+void nr_enquiry_response(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+	int frametype = NR_INFOACK;
+
+	if (nr->condition & NR_COND_OWN_RX_BUSY) {
+		frametype |= NR_CHOKE_FLAG;
+	} else {
+		if (skb_peek(&nr->reseq_queue) != NULL)
+			frametype |= NR_NAK_FLAG;
+	}
+
+	nr_write_internal(sk, frametype);
+
+	nr->vl         = nr->vr;
+	nr->condition &= ~NR_COND_ACK_PENDING;
+}
+
+void nr_check_iframes_acked(struct sock *sk, unsigned short nr)
+{
+	struct nr_sock *nrom = nr_sk(sk);
+
+	if (nrom->vs == nr) {
+		nr_frames_acked(sk, nr);
+		nr_stop_t1timer(sk);
+		nrom->n2count = 0;
+	} else {
+		if (nrom->va != nr) {
+			nr_frames_acked(sk, nr);
+			nr_start_t1timer(sk);
+		}
+	}
+}
diff --git a/net/netrom/nr_route.c b/net/netrom/nr_route.c
new file mode 100644
index 000000000..baea3cbd7
--- /dev/null
+++ b/net/netrom/nr_route.c
@@ -0,0 +1,983 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ * Copyright Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
+ * Copyright Tomi Manninen OH2BNS (oh2bns@sral.fi)
+ */
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/slab.h>
+#include <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <net/arp.h>
+#include <linux/if_arp.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <linux/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/termios.h>	/* For TIOCINQ/OUTQ */
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/notifier.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <net/netrom.h>
+#include <linux/seq_file.h>
+#include <linux/export.h>
+
+static unsigned int nr_neigh_no = 1;
+
+static HLIST_HEAD(nr_node_list);
+static DEFINE_SPINLOCK(nr_node_list_lock);
+static HLIST_HEAD(nr_neigh_list);
+static DEFINE_SPINLOCK(nr_neigh_list_lock);
+
+static struct nr_node *nr_node_get(ax25_address *callsign)
+{
+	struct nr_node *found = NULL;
+	struct nr_node *nr_node;
+
+	spin_lock_bh(&nr_node_list_lock);
+	nr_node_for_each(nr_node, &nr_node_list)
+		if (ax25cmp(callsign, &nr_node->callsign) == 0) {
+			nr_node_hold(nr_node);
+			found = nr_node;
+			break;
+		}
+	spin_unlock_bh(&nr_node_list_lock);
+	return found;
+}
+
+static struct nr_neigh *nr_neigh_get_dev(ax25_address *callsign,
+					 struct net_device *dev)
+{
+	struct nr_neigh *found = NULL;
+	struct nr_neigh *nr_neigh;
+
+	spin_lock_bh(&nr_neigh_list_lock);
+	nr_neigh_for_each(nr_neigh, &nr_neigh_list)
+		if (ax25cmp(callsign, &nr_neigh->callsign) == 0 &&
+		    nr_neigh->dev == dev) {
+			nr_neigh_hold(nr_neigh);
+			found = nr_neigh;
+			break;
+		}
+	spin_unlock_bh(&nr_neigh_list_lock);
+	return found;
+}
+
+static void nr_remove_neigh(struct nr_neigh *);
+
+/*      re-sort the routes in quality order.    */
+static void re_sort_routes(struct nr_node *nr_node, int x, int y)
+{
+	if (nr_node->routes[y].quality > nr_node->routes[x].quality) {
+		if (nr_node->which == x)
+			nr_node->which = y;
+		else if (nr_node->which == y)
+			nr_node->which = x;
+
+		swap(nr_node->routes[x], nr_node->routes[y]);
+	}
+}
+
+/*
+ *	Add a new route to a node, and in the process add the node and the
+ *	neighbour if it is new.
+ */
+static int __must_check nr_add_node(ax25_address *nr, const char *mnemonic,
+	ax25_address *ax25, ax25_digi *ax25_digi, struct net_device *dev,
+	int quality, int obs_count)
+{
+	struct nr_node  *nr_node;
+	struct nr_neigh *nr_neigh;
+	int i, found;
+	struct net_device *odev;
+
+	if ((odev=nr_dev_get(nr)) != NULL) {	/* Can't add routes to ourself */
+		dev_put(odev);
+		return -EINVAL;
+	}
+
+	nr_node = nr_node_get(nr);
+
+	nr_neigh = nr_neigh_get_dev(ax25, dev);
+
+	/*
+	 * The L2 link to a neighbour has failed in the past
+	 * and now a frame comes from this neighbour. We assume
+	 * it was a temporary trouble with the link and reset the
+	 * routes now (and not wait for a node broadcast).
+	 */
+	if (nr_neigh != NULL && nr_neigh->failed != 0 && quality == 0) {
+		struct nr_node *nr_nodet;
+
+		spin_lock_bh(&nr_node_list_lock);
+		nr_node_for_each(nr_nodet, &nr_node_list) {
+			nr_node_lock(nr_nodet);
+			for (i = 0; i < nr_nodet->count; i++)
+				if (nr_nodet->routes[i].neighbour == nr_neigh)
+					if (i < nr_nodet->which)
+						nr_nodet->which = i;
+			nr_node_unlock(nr_nodet);
+		}
+		spin_unlock_bh(&nr_node_list_lock);
+	}
+
+	if (nr_neigh != NULL)
+		nr_neigh->failed = 0;
+
+	if (quality == 0 && nr_neigh != NULL && nr_node != NULL) {
+		nr_neigh_put(nr_neigh);
+		nr_node_put(nr_node);
+		return 0;
+	}
+
+	if (nr_neigh == NULL) {
+		if ((nr_neigh = kmalloc(sizeof(*nr_neigh), GFP_ATOMIC)) == NULL) {
+			if (nr_node)
+				nr_node_put(nr_node);
+			return -ENOMEM;
+		}
+
+		nr_neigh->callsign = *ax25;
+		nr_neigh->digipeat = NULL;
+		nr_neigh->ax25     = NULL;
+		nr_neigh->dev      = dev;
+		nr_neigh->quality  = sysctl_netrom_default_path_quality;
+		nr_neigh->locked   = 0;
+		nr_neigh->count    = 0;
+		nr_neigh->number   = nr_neigh_no++;
+		nr_neigh->failed   = 0;
+		refcount_set(&nr_neigh->refcount, 1);
+
+		if (ax25_digi != NULL && ax25_digi->ndigi > 0) {
+			nr_neigh->digipeat = kmemdup(ax25_digi,
+						     sizeof(*ax25_digi),
+						     GFP_KERNEL);
+			if (nr_neigh->digipeat == NULL) {
+				kfree(nr_neigh);
+				if (nr_node)
+					nr_node_put(nr_node);
+				return -ENOMEM;
+			}
+		}
+
+		spin_lock_bh(&nr_neigh_list_lock);
+		hlist_add_head(&nr_neigh->neigh_node, &nr_neigh_list);
+		nr_neigh_hold(nr_neigh);
+		spin_unlock_bh(&nr_neigh_list_lock);
+	}
+
+	if (quality != 0 && ax25cmp(nr, ax25) == 0 && !nr_neigh->locked)
+		nr_neigh->quality = quality;
+
+	if (nr_node == NULL) {
+		if ((nr_node = kmalloc(sizeof(*nr_node), GFP_ATOMIC)) == NULL) {
+			if (nr_neigh)
+				nr_neigh_put(nr_neigh);
+			return -ENOMEM;
+		}
+
+		nr_node->callsign = *nr;
+		strcpy(nr_node->mnemonic, mnemonic);
+
+		nr_node->which = 0;
+		nr_node->count = 1;
+		refcount_set(&nr_node->refcount, 1);
+		spin_lock_init(&nr_node->node_lock);
+
+		nr_node->routes[0].quality   = quality;
+		nr_node->routes[0].obs_count = obs_count;
+		nr_node->routes[0].neighbour = nr_neigh;
+
+		nr_neigh_hold(nr_neigh);
+		nr_neigh->count++;
+
+		spin_lock_bh(&nr_node_list_lock);
+		hlist_add_head(&nr_node->node_node, &nr_node_list);
+		/* refcount initialized at 1 */
+		spin_unlock_bh(&nr_node_list_lock);
+
+		nr_neigh_put(nr_neigh);
+		return 0;
+	}
+	nr_node_lock(nr_node);
+
+	if (quality != 0)
+		strcpy(nr_node->mnemonic, mnemonic);
+
+	for (found = 0, i = 0; i < nr_node->count; i++) {
+		if (nr_node->routes[i].neighbour == nr_neigh) {
+			nr_node->routes[i].quality   = quality;
+			nr_node->routes[i].obs_count = obs_count;
+			found = 1;
+			break;
+		}
+	}
+
+	if (!found) {
+		/* We have space at the bottom, slot it in */
+		if (nr_node->count < 3) {
+			nr_node->routes[2] = nr_node->routes[1];
+			nr_node->routes[1] = nr_node->routes[0];
+
+			nr_node->routes[0].quality   = quality;
+			nr_node->routes[0].obs_count = obs_count;
+			nr_node->routes[0].neighbour = nr_neigh;
+
+			nr_node->which++;
+			nr_node->count++;
+			nr_neigh_hold(nr_neigh);
+			nr_neigh->count++;
+		} else {
+			/* It must be better than the worst */
+			if (quality > nr_node->routes[2].quality) {
+				nr_node->routes[2].neighbour->count--;
+				nr_neigh_put(nr_node->routes[2].neighbour);
+
+				if (nr_node->routes[2].neighbour->count == 0 && !nr_node->routes[2].neighbour->locked)
+					nr_remove_neigh(nr_node->routes[2].neighbour);
+
+				nr_node->routes[2].quality   = quality;
+				nr_node->routes[2].obs_count = obs_count;
+				nr_node->routes[2].neighbour = nr_neigh;
+
+				nr_neigh_hold(nr_neigh);
+				nr_neigh->count++;
+			}
+		}
+	}
+
+	/* Now re-sort the routes in quality order */
+	switch (nr_node->count) {
+	case 3:
+		re_sort_routes(nr_node, 0, 1);
+		re_sort_routes(nr_node, 1, 2);
+		fallthrough;
+	case 2:
+		re_sort_routes(nr_node, 0, 1);
+		break;
+	case 1:
+		break;
+	}
+
+	for (i = 0; i < nr_node->count; i++) {
+		if (nr_node->routes[i].neighbour == nr_neigh) {
+			if (i < nr_node->which)
+				nr_node->which = i;
+			break;
+		}
+	}
+
+	nr_neigh_put(nr_neigh);
+	nr_node_unlock(nr_node);
+	nr_node_put(nr_node);
+	return 0;
+}
+
+static inline void __nr_remove_node(struct nr_node *nr_node)
+{
+	hlist_del_init(&nr_node->node_node);
+	nr_node_put(nr_node);
+}
+
+#define nr_remove_node_locked(__node) \
+	__nr_remove_node(__node)
+
+static void nr_remove_node(struct nr_node *nr_node)
+{
+	spin_lock_bh(&nr_node_list_lock);
+	__nr_remove_node(nr_node);
+	spin_unlock_bh(&nr_node_list_lock);
+}
+
+static inline void __nr_remove_neigh(struct nr_neigh *nr_neigh)
+{
+	hlist_del_init(&nr_neigh->neigh_node);
+	nr_neigh_put(nr_neigh);
+}
+
+#define nr_remove_neigh_locked(__neigh) \
+	__nr_remove_neigh(__neigh)
+
+static void nr_remove_neigh(struct nr_neigh *nr_neigh)
+{
+	spin_lock_bh(&nr_neigh_list_lock);
+	__nr_remove_neigh(nr_neigh);
+	spin_unlock_bh(&nr_neigh_list_lock);
+}
+
+/*
+ *	"Delete" a node. Strictly speaking remove a route to a node. The node
+ *	is only deleted if no routes are left to it.
+ */
+static int nr_del_node(ax25_address *callsign, ax25_address *neighbour, struct net_device *dev)
+{
+	struct nr_node  *nr_node;
+	struct nr_neigh *nr_neigh;
+	int i;
+
+	nr_node = nr_node_get(callsign);
+
+	if (nr_node == NULL)
+		return -EINVAL;
+
+	nr_neigh = nr_neigh_get_dev(neighbour, dev);
+
+	if (nr_neigh == NULL) {
+		nr_node_put(nr_node);
+		return -EINVAL;
+	}
+
+	nr_node_lock(nr_node);
+	for (i = 0; i < nr_node->count; i++) {
+		if (nr_node->routes[i].neighbour == nr_neigh) {
+			nr_neigh->count--;
+			nr_neigh_put(nr_neigh);
+
+			if (nr_neigh->count == 0 && !nr_neigh->locked)
+				nr_remove_neigh(nr_neigh);
+			nr_neigh_put(nr_neigh);
+
+			nr_node->count--;
+
+			if (nr_node->count == 0) {
+				nr_remove_node(nr_node);
+			} else {
+				switch (i) {
+				case 0:
+					nr_node->routes[0] = nr_node->routes[1];
+					fallthrough;
+				case 1:
+					nr_node->routes[1] = nr_node->routes[2];
+					fallthrough;
+				case 2:
+					break;
+				}
+				nr_node_put(nr_node);
+			}
+			nr_node_unlock(nr_node);
+
+			return 0;
+		}
+	}
+	nr_neigh_put(nr_neigh);
+	nr_node_unlock(nr_node);
+	nr_node_put(nr_node);
+
+	return -EINVAL;
+}
+
+/*
+ *	Lock a neighbour with a quality.
+ */
+static int __must_check nr_add_neigh(ax25_address *callsign,
+	ax25_digi *ax25_digi, struct net_device *dev, unsigned int quality)
+{
+	struct nr_neigh *nr_neigh;
+
+	nr_neigh = nr_neigh_get_dev(callsign, dev);
+	if (nr_neigh) {
+		nr_neigh->quality = quality;
+		nr_neigh->locked  = 1;
+		nr_neigh_put(nr_neigh);
+		return 0;
+	}
+
+	if ((nr_neigh = kmalloc(sizeof(*nr_neigh), GFP_ATOMIC)) == NULL)
+		return -ENOMEM;
+
+	nr_neigh->callsign = *callsign;
+	nr_neigh->digipeat = NULL;
+	nr_neigh->ax25     = NULL;
+	nr_neigh->dev      = dev;
+	nr_neigh->quality  = quality;
+	nr_neigh->locked   = 1;
+	nr_neigh->count    = 0;
+	nr_neigh->number   = nr_neigh_no++;
+	nr_neigh->failed   = 0;
+	refcount_set(&nr_neigh->refcount, 1);
+
+	if (ax25_digi != NULL && ax25_digi->ndigi > 0) {
+		nr_neigh->digipeat = kmemdup(ax25_digi, sizeof(*ax25_digi),
+					     GFP_KERNEL);
+		if (nr_neigh->digipeat == NULL) {
+			kfree(nr_neigh);
+			return -ENOMEM;
+		}
+	}
+
+	spin_lock_bh(&nr_neigh_list_lock);
+	hlist_add_head(&nr_neigh->neigh_node, &nr_neigh_list);
+	/* refcount is initialized at 1 */
+	spin_unlock_bh(&nr_neigh_list_lock);
+
+	return 0;
+}
+
+/*
+ *	"Delete" a neighbour. The neighbour is only removed if the number
+ *	of nodes that may use it is zero.
+ */
+static int nr_del_neigh(ax25_address *callsign, struct net_device *dev, unsigned int quality)
+{
+	struct nr_neigh *nr_neigh;
+
+	nr_neigh = nr_neigh_get_dev(callsign, dev);
+
+	if (nr_neigh == NULL) return -EINVAL;
+
+	nr_neigh->quality = quality;
+	nr_neigh->locked  = 0;
+
+	if (nr_neigh->count == 0)
+		nr_remove_neigh(nr_neigh);
+	nr_neigh_put(nr_neigh);
+
+	return 0;
+}
+
+/*
+ *	Decrement the obsolescence count by one. If a route is reduced to a
+ *	count of zero, remove it. Also remove any unlocked neighbours with
+ *	zero nodes routing via it.
+ */
+static int nr_dec_obs(void)
+{
+	struct nr_neigh *nr_neigh;
+	struct nr_node  *s;
+	struct hlist_node *nodet;
+	int i;
+
+	spin_lock_bh(&nr_node_list_lock);
+	nr_node_for_each_safe(s, nodet, &nr_node_list) {
+		nr_node_lock(s);
+		for (i = 0; i < s->count; i++) {
+			switch (s->routes[i].obs_count) {
+			case 0:		/* A locked entry */
+				break;
+
+			case 1:		/* From 1 -> 0 */
+				nr_neigh = s->routes[i].neighbour;
+
+				nr_neigh->count--;
+				nr_neigh_put(nr_neigh);
+
+				if (nr_neigh->count == 0 && !nr_neigh->locked)
+					nr_remove_neigh(nr_neigh);
+
+				s->count--;
+
+				switch (i) {
+				case 0:
+					s->routes[0] = s->routes[1];
+					fallthrough;
+				case 1:
+					s->routes[1] = s->routes[2];
+					break;
+				case 2:
+					break;
+				}
+				break;
+
+			default:
+				s->routes[i].obs_count--;
+				break;
+
+			}
+		}
+
+		if (s->count <= 0)
+			nr_remove_node_locked(s);
+		nr_node_unlock(s);
+	}
+	spin_unlock_bh(&nr_node_list_lock);
+
+	return 0;
+}
+
+/*
+ *	A device has been removed. Remove its routes and neighbours.
+ */
+void nr_rt_device_down(struct net_device *dev)
+{
+	struct nr_neigh *s;
+	struct hlist_node *nodet, *node2t;
+	struct nr_node  *t;
+	int i;
+
+	spin_lock_bh(&nr_neigh_list_lock);
+	nr_neigh_for_each_safe(s, nodet, &nr_neigh_list) {
+		if (s->dev == dev) {
+			spin_lock_bh(&nr_node_list_lock);
+			nr_node_for_each_safe(t, node2t, &nr_node_list) {
+				nr_node_lock(t);
+				for (i = 0; i < t->count; i++) {
+					if (t->routes[i].neighbour == s) {
+						t->count--;
+
+						switch (i) {
+						case 0:
+							t->routes[0] = t->routes[1];
+							fallthrough;
+						case 1:
+							t->routes[1] = t->routes[2];
+							break;
+						case 2:
+							break;
+						}
+					}
+				}
+
+				if (t->count <= 0)
+					nr_remove_node_locked(t);
+				nr_node_unlock(t);
+			}
+			spin_unlock_bh(&nr_node_list_lock);
+
+			nr_remove_neigh_locked(s);
+		}
+	}
+	spin_unlock_bh(&nr_neigh_list_lock);
+}
+
+/*
+ *	Check that the device given is a valid AX.25 interface that is "up".
+ *	Or a valid ethernet interface with an AX.25 callsign binding.
+ */
+static struct net_device *nr_ax25_dev_get(char *devname)
+{
+	struct net_device *dev;
+
+	if ((dev = dev_get_by_name(&init_net, devname)) == NULL)
+		return NULL;
+
+	if ((dev->flags & IFF_UP) && dev->type == ARPHRD_AX25)
+		return dev;
+
+	dev_put(dev);
+	return NULL;
+}
+
+/*
+ *	Find the first active NET/ROM device, usually "nr0".
+ */
+struct net_device *nr_dev_first(void)
+{
+	struct net_device *dev, *first = NULL;
+
+	rcu_read_lock();
+	for_each_netdev_rcu(&init_net, dev) {
+		if ((dev->flags & IFF_UP) && dev->type == ARPHRD_NETROM)
+			if (first == NULL || strncmp(dev->name, first->name, 3) < 0)
+				first = dev;
+	}
+	dev_hold(first);
+	rcu_read_unlock();
+
+	return first;
+}
+
+/*
+ *	Find the NET/ROM device for the given callsign.
+ */
+struct net_device *nr_dev_get(ax25_address *addr)
+{
+	struct net_device *dev;
+
+	rcu_read_lock();
+	for_each_netdev_rcu(&init_net, dev) {
+		if ((dev->flags & IFF_UP) && dev->type == ARPHRD_NETROM &&
+		    ax25cmp(addr, (const ax25_address *)dev->dev_addr) == 0) {
+			dev_hold(dev);
+			goto out;
+		}
+	}
+	dev = NULL;
+out:
+	rcu_read_unlock();
+	return dev;
+}
+
+static ax25_digi *nr_call_to_digi(ax25_digi *digi, int ndigis,
+	ax25_address *digipeaters)
+{
+	int i;
+
+	if (ndigis == 0)
+		return NULL;
+
+	for (i = 0; i < ndigis; i++) {
+		digi->calls[i]    = digipeaters[i];
+		digi->repeated[i] = 0;
+	}
+
+	digi->ndigi      = ndigis;
+	digi->lastrepeat = -1;
+
+	return digi;
+}
+
+/*
+ *	Handle the ioctls that control the routing functions.
+ */
+int nr_rt_ioctl(unsigned int cmd, void __user *arg)
+{
+	struct nr_route_struct nr_route;
+	struct net_device *dev;
+	ax25_digi digi;
+	int ret;
+
+	switch (cmd) {
+	case SIOCADDRT:
+		if (copy_from_user(&nr_route, arg, sizeof(struct nr_route_struct)))
+			return -EFAULT;
+		if (nr_route.ndigis > AX25_MAX_DIGIS)
+			return -EINVAL;
+		if ((dev = nr_ax25_dev_get(nr_route.device)) == NULL)
+			return -EINVAL;
+		switch (nr_route.type) {
+		case NETROM_NODE:
+			if (strnlen(nr_route.mnemonic, 7) == 7) {
+				ret = -EINVAL;
+				break;
+			}
+
+			ret = nr_add_node(&nr_route.callsign,
+				nr_route.mnemonic,
+				&nr_route.neighbour,
+				nr_call_to_digi(&digi, nr_route.ndigis,
+						nr_route.digipeaters),
+				dev, nr_route.quality,
+				nr_route.obs_count);
+			break;
+		case NETROM_NEIGH:
+			ret = nr_add_neigh(&nr_route.callsign,
+				nr_call_to_digi(&digi, nr_route.ndigis,
+						nr_route.digipeaters),
+				dev, nr_route.quality);
+			break;
+		default:
+			ret = -EINVAL;
+		}
+		dev_put(dev);
+		return ret;
+
+	case SIOCDELRT:
+		if (copy_from_user(&nr_route, arg, sizeof(struct nr_route_struct)))
+			return -EFAULT;
+		if ((dev = nr_ax25_dev_get(nr_route.device)) == NULL)
+			return -EINVAL;
+		switch (nr_route.type) {
+		case NETROM_NODE:
+			ret = nr_del_node(&nr_route.callsign,
+				&nr_route.neighbour, dev);
+			break;
+		case NETROM_NEIGH:
+			ret = nr_del_neigh(&nr_route.callsign,
+				dev, nr_route.quality);
+			break;
+		default:
+			ret = -EINVAL;
+		}
+		dev_put(dev);
+		return ret;
+
+	case SIOCNRDECOBS:
+		return nr_dec_obs();
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * 	A level 2 link has timed out, therefore it appears to be a poor link,
+ *	then don't use that neighbour until it is reset.
+ */
+void nr_link_failed(ax25_cb *ax25, int reason)
+{
+	struct nr_neigh *s, *nr_neigh = NULL;
+	struct nr_node  *nr_node = NULL;
+
+	spin_lock_bh(&nr_neigh_list_lock);
+	nr_neigh_for_each(s, &nr_neigh_list) {
+		if (s->ax25 == ax25) {
+			nr_neigh_hold(s);
+			nr_neigh = s;
+			break;
+		}
+	}
+	spin_unlock_bh(&nr_neigh_list_lock);
+
+	if (nr_neigh == NULL)
+		return;
+
+	nr_neigh->ax25 = NULL;
+	ax25_cb_put(ax25);
+
+	if (++nr_neigh->failed < sysctl_netrom_link_fails_count) {
+		nr_neigh_put(nr_neigh);
+		return;
+	}
+	spin_lock_bh(&nr_node_list_lock);
+	nr_node_for_each(nr_node, &nr_node_list) {
+		nr_node_lock(nr_node);
+		if (nr_node->which < nr_node->count &&
+		    nr_node->routes[nr_node->which].neighbour == nr_neigh)
+			nr_node->which++;
+		nr_node_unlock(nr_node);
+	}
+	spin_unlock_bh(&nr_node_list_lock);
+	nr_neigh_put(nr_neigh);
+}
+
+/*
+ *	Route a frame to an appropriate AX.25 connection. A NULL ax25_cb
+ *	indicates an internally generated frame.
+ */
+int nr_route_frame(struct sk_buff *skb, ax25_cb *ax25)
+{
+	ax25_address *nr_src, *nr_dest;
+	struct nr_neigh *nr_neigh;
+	struct nr_node  *nr_node;
+	struct net_device *dev;
+	unsigned char *dptr;
+	ax25_cb *ax25s;
+	int ret;
+	struct sk_buff *skbn;
+
+
+	nr_src  = (ax25_address *)(skb->data + 0);
+	nr_dest = (ax25_address *)(skb->data + 7);
+
+	if (ax25 != NULL) {
+		ret = nr_add_node(nr_src, "", &ax25->dest_addr, ax25->digipeat,
+				  ax25->ax25_dev->dev, 0,
+				  sysctl_netrom_obsolescence_count_initialiser);
+		if (ret)
+			return ret;
+	}
+
+	if ((dev = nr_dev_get(nr_dest)) != NULL) {	/* Its for me */
+		if (ax25 == NULL)			/* Its from me */
+			ret = nr_loopback_queue(skb);
+		else
+			ret = nr_rx_frame(skb, dev);
+		dev_put(dev);
+		return ret;
+	}
+
+	if (!sysctl_netrom_routing_control && ax25 != NULL)
+		return 0;
+
+	/* Its Time-To-Live has expired */
+	if (skb->data[14] == 1) {
+		return 0;
+	}
+
+	nr_node = nr_node_get(nr_dest);
+	if (nr_node == NULL)
+		return 0;
+	nr_node_lock(nr_node);
+
+	if (nr_node->which >= nr_node->count) {
+		nr_node_unlock(nr_node);
+		nr_node_put(nr_node);
+		return 0;
+	}
+
+	nr_neigh = nr_node->routes[nr_node->which].neighbour;
+
+	if ((dev = nr_dev_first()) == NULL) {
+		nr_node_unlock(nr_node);
+		nr_node_put(nr_node);
+		return 0;
+	}
+
+	/* We are going to change the netrom headers so we should get our
+	   own skb, we also did not know until now how much header space
+	   we had to reserve... - RXQ */
+	if ((skbn=skb_copy_expand(skb, dev->hard_header_len, 0, GFP_ATOMIC)) == NULL) {
+		nr_node_unlock(nr_node);
+		nr_node_put(nr_node);
+		dev_put(dev);
+		return 0;
+	}
+	kfree_skb(skb);
+	skb=skbn;
+	skb->data[14]--;
+
+	dptr  = skb_push(skb, 1);
+	*dptr = AX25_P_NETROM;
+
+	ax25s = nr_neigh->ax25;
+	nr_neigh->ax25 = ax25_send_frame(skb, 256,
+					 (const ax25_address *)dev->dev_addr,
+					 &nr_neigh->callsign,
+					 nr_neigh->digipeat, nr_neigh->dev);
+	if (ax25s)
+		ax25_cb_put(ax25s);
+
+	dev_put(dev);
+	ret = (nr_neigh->ax25 != NULL);
+	nr_node_unlock(nr_node);
+	nr_node_put(nr_node);
+
+	return ret;
+}
+
+#ifdef CONFIG_PROC_FS
+
+static void *nr_node_start(struct seq_file *seq, loff_t *pos)
+	__acquires(&nr_node_list_lock)
+{
+	spin_lock_bh(&nr_node_list_lock);
+	return seq_hlist_start_head(&nr_node_list, *pos);
+}
+
+static void *nr_node_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	return seq_hlist_next(v, &nr_node_list, pos);
+}
+
+static void nr_node_stop(struct seq_file *seq, void *v)
+	__releases(&nr_node_list_lock)
+{
+	spin_unlock_bh(&nr_node_list_lock);
+}
+
+static int nr_node_show(struct seq_file *seq, void *v)
+{
+	char buf[11];
+	int i;
+
+	if (v == SEQ_START_TOKEN)
+		seq_puts(seq,
+			 "callsign  mnemonic w n qual obs neigh qual obs neigh qual obs neigh\n");
+	else {
+		struct nr_node *nr_node = hlist_entry(v, struct nr_node,
+						      node_node);
+
+		nr_node_lock(nr_node);
+		seq_printf(seq, "%-9s %-7s  %d %d",
+			ax2asc(buf, &nr_node->callsign),
+			(nr_node->mnemonic[0] == '\0') ? "*" : nr_node->mnemonic,
+			nr_node->which + 1,
+			nr_node->count);
+
+		for (i = 0; i < nr_node->count; i++) {
+			seq_printf(seq, "  %3d   %d %05d",
+				nr_node->routes[i].quality,
+				nr_node->routes[i].obs_count,
+				nr_node->routes[i].neighbour->number);
+		}
+		nr_node_unlock(nr_node);
+
+		seq_puts(seq, "\n");
+	}
+	return 0;
+}
+
+const struct seq_operations nr_node_seqops = {
+	.start = nr_node_start,
+	.next = nr_node_next,
+	.stop = nr_node_stop,
+	.show = nr_node_show,
+};
+
+static void *nr_neigh_start(struct seq_file *seq, loff_t *pos)
+	__acquires(&nr_neigh_list_lock)
+{
+	spin_lock_bh(&nr_neigh_list_lock);
+	return seq_hlist_start_head(&nr_neigh_list, *pos);
+}
+
+static void *nr_neigh_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	return seq_hlist_next(v, &nr_neigh_list, pos);
+}
+
+static void nr_neigh_stop(struct seq_file *seq, void *v)
+	__releases(&nr_neigh_list_lock)
+{
+	spin_unlock_bh(&nr_neigh_list_lock);
+}
+
+static int nr_neigh_show(struct seq_file *seq, void *v)
+{
+	char buf[11];
+	int i;
+
+	if (v == SEQ_START_TOKEN)
+		seq_puts(seq, "addr  callsign  dev  qual lock count failed digipeaters\n");
+	else {
+		struct nr_neigh *nr_neigh;
+
+		nr_neigh = hlist_entry(v, struct nr_neigh, neigh_node);
+		seq_printf(seq, "%05d %-9s %-4s  %3d    %d   %3d    %3d",
+			nr_neigh->number,
+			ax2asc(buf, &nr_neigh->callsign),
+			nr_neigh->dev ? nr_neigh->dev->name : "???",
+			nr_neigh->quality,
+			nr_neigh->locked,
+			nr_neigh->count,
+			nr_neigh->failed);
+
+		if (nr_neigh->digipeat != NULL) {
+			for (i = 0; i < nr_neigh->digipeat->ndigi; i++)
+				seq_printf(seq, " %s",
+					   ax2asc(buf, &nr_neigh->digipeat->calls[i]));
+		}
+
+		seq_puts(seq, "\n");
+	}
+	return 0;
+}
+
+const struct seq_operations nr_neigh_seqops = {
+	.start = nr_neigh_start,
+	.next = nr_neigh_next,
+	.stop = nr_neigh_stop,
+	.show = nr_neigh_show,
+};
+#endif
+
+/*
+ *	Free all memory associated with the nodes and routes lists.
+ */
+void nr_rt_free(void)
+{
+	struct nr_neigh *s = NULL;
+	struct nr_node  *t = NULL;
+	struct hlist_node *nodet;
+
+	spin_lock_bh(&nr_neigh_list_lock);
+	spin_lock_bh(&nr_node_list_lock);
+	nr_node_for_each_safe(t, nodet, &nr_node_list) {
+		nr_node_lock(t);
+		nr_remove_node_locked(t);
+		nr_node_unlock(t);
+	}
+	nr_neigh_for_each_safe(s, nodet, &nr_neigh_list) {
+		while(s->count) {
+			s->count--;
+			nr_neigh_put(s);
+		}
+		nr_remove_neigh_locked(s);
+	}
+	spin_unlock_bh(&nr_node_list_lock);
+	spin_unlock_bh(&nr_neigh_list_lock);
+}
diff --git a/net/netrom/nr_subr.c b/net/netrom/nr_subr.c
new file mode 100644
index 000000000..e2d2af924
--- /dev/null
+++ b/net/netrom/nr_subr.c
@@ -0,0 +1,279 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ */
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/slab.h>
+#include <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <linux/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/netrom.h>
+
+/*
+ *	This routine purges all of the queues of frames.
+ */
+void nr_clear_queues(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+
+	skb_queue_purge(&sk->sk_write_queue);
+	skb_queue_purge(&nr->ack_queue);
+	skb_queue_purge(&nr->reseq_queue);
+	skb_queue_purge(&nr->frag_queue);
+}
+
+/*
+ * This routine purges the input queue of those frames that have been
+ * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
+ * SDL diagram.
+ */
+void nr_frames_acked(struct sock *sk, unsigned short nr)
+{
+	struct nr_sock *nrom = nr_sk(sk);
+	struct sk_buff *skb;
+
+	/*
+	 * Remove all the ack-ed frames from the ack queue.
+	 */
+	if (nrom->va != nr) {
+		while (skb_peek(&nrom->ack_queue) != NULL && nrom->va != nr) {
+			skb = skb_dequeue(&nrom->ack_queue);
+			kfree_skb(skb);
+			nrom->va = (nrom->va + 1) % NR_MODULUS;
+		}
+	}
+}
+
+/*
+ * Requeue all the un-ack-ed frames on the output queue to be picked
+ * up by nr_kick called from the timer. This arrangement handles the
+ * possibility of an empty output queue.
+ */
+void nr_requeue_frames(struct sock *sk)
+{
+	struct sk_buff *skb, *skb_prev = NULL;
+
+	while ((skb = skb_dequeue(&nr_sk(sk)->ack_queue)) != NULL) {
+		if (skb_prev == NULL)
+			skb_queue_head(&sk->sk_write_queue, skb);
+		else
+			skb_append(skb_prev, skb, &sk->sk_write_queue);
+		skb_prev = skb;
+	}
+}
+
+/*
+ *	Validate that the value of nr is between va and vs. Return true or
+ *	false for testing.
+ */
+int nr_validate_nr(struct sock *sk, unsigned short nr)
+{
+	struct nr_sock *nrom = nr_sk(sk);
+	unsigned short vc = nrom->va;
+
+	while (vc != nrom->vs) {
+		if (nr == vc) return 1;
+		vc = (vc + 1) % NR_MODULUS;
+	}
+
+	return nr == nrom->vs;
+}
+
+/*
+ *	Check that ns is within the receive window.
+ */
+int nr_in_rx_window(struct sock *sk, unsigned short ns)
+{
+	struct nr_sock *nr = nr_sk(sk);
+	unsigned short vc = nr->vr;
+	unsigned short vt = (nr->vl + nr->window) % NR_MODULUS;
+
+	while (vc != vt) {
+		if (ns == vc) return 1;
+		vc = (vc + 1) % NR_MODULUS;
+	}
+
+	return 0;
+}
+
+/*
+ *  This routine is called when the HDLC layer internally generates a
+ *  control frame.
+ */
+void nr_write_internal(struct sock *sk, int frametype)
+{
+	struct nr_sock *nr = nr_sk(sk);
+	struct sk_buff *skb;
+	unsigned char  *dptr;
+	int len, timeout;
+
+	len = NR_TRANSPORT_LEN;
+
+	switch (frametype & 0x0F) {
+	case NR_CONNREQ:
+		len += 17;
+		break;
+	case NR_CONNACK:
+		len += (nr->bpqext) ? 2 : 1;
+		break;
+	case NR_DISCREQ:
+	case NR_DISCACK:
+	case NR_INFOACK:
+		break;
+	default:
+		printk(KERN_ERR "NET/ROM: nr_write_internal - invalid frame type %d\n", frametype);
+		return;
+	}
+
+	skb = alloc_skb(NR_NETWORK_LEN + len, GFP_ATOMIC);
+	if (!skb)
+		return;
+
+	/*
+	 *	Space for AX.25 and NET/ROM network header
+	 */
+	skb_reserve(skb, NR_NETWORK_LEN);
+
+	dptr = skb_put(skb, len);
+
+	switch (frametype & 0x0F) {
+	case NR_CONNREQ:
+		timeout  = nr->t1 / HZ;
+		*dptr++  = nr->my_index;
+		*dptr++  = nr->my_id;
+		*dptr++  = 0;
+		*dptr++  = 0;
+		*dptr++  = frametype;
+		*dptr++  = nr->window;
+		memcpy(dptr, &nr->user_addr, AX25_ADDR_LEN);
+		dptr[6] &= ~AX25_CBIT;
+		dptr[6] &= ~AX25_EBIT;
+		dptr[6] |= AX25_SSSID_SPARE;
+		dptr    += AX25_ADDR_LEN;
+		memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
+		dptr[6] &= ~AX25_CBIT;
+		dptr[6] &= ~AX25_EBIT;
+		dptr[6] |= AX25_SSSID_SPARE;
+		dptr    += AX25_ADDR_LEN;
+		*dptr++  = timeout % 256;
+		*dptr++  = timeout / 256;
+		break;
+
+	case NR_CONNACK:
+		*dptr++ = nr->your_index;
+		*dptr++ = nr->your_id;
+		*dptr++ = nr->my_index;
+		*dptr++ = nr->my_id;
+		*dptr++ = frametype;
+		*dptr++ = nr->window;
+		if (nr->bpqext) *dptr++ = sysctl_netrom_network_ttl_initialiser;
+		break;
+
+	case NR_DISCREQ:
+	case NR_DISCACK:
+		*dptr++ = nr->your_index;
+		*dptr++ = nr->your_id;
+		*dptr++ = 0;
+		*dptr++ = 0;
+		*dptr++ = frametype;
+		break;
+
+	case NR_INFOACK:
+		*dptr++ = nr->your_index;
+		*dptr++ = nr->your_id;
+		*dptr++ = 0;
+		*dptr++ = nr->vr;
+		*dptr++ = frametype;
+		break;
+	}
+
+	nr_transmit_buffer(sk, skb);
+}
+
+/*
+ * This routine is called to send an error reply.
+ */
+void __nr_transmit_reply(struct sk_buff *skb, int mine, unsigned char cmdflags)
+{
+	struct sk_buff *skbn;
+	unsigned char *dptr;
+	int len;
+
+	len = NR_NETWORK_LEN + NR_TRANSPORT_LEN + 1;
+
+	if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL)
+		return;
+
+	skb_reserve(skbn, 0);
+
+	dptr = skb_put(skbn, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
+
+	skb_copy_from_linear_data_offset(skb, 7, dptr, AX25_ADDR_LEN);
+	dptr[6] &= ~AX25_CBIT;
+	dptr[6] &= ~AX25_EBIT;
+	dptr[6] |= AX25_SSSID_SPARE;
+	dptr += AX25_ADDR_LEN;
+
+	skb_copy_from_linear_data(skb, dptr, AX25_ADDR_LEN);
+	dptr[6] &= ~AX25_CBIT;
+	dptr[6] |= AX25_EBIT;
+	dptr[6] |= AX25_SSSID_SPARE;
+	dptr += AX25_ADDR_LEN;
+
+	*dptr++ = sysctl_netrom_network_ttl_initialiser;
+
+	if (mine) {
+		*dptr++ = 0;
+		*dptr++ = 0;
+		*dptr++ = skb->data[15];
+		*dptr++ = skb->data[16];
+	} else {
+		*dptr++ = skb->data[15];
+		*dptr++ = skb->data[16];
+		*dptr++ = 0;
+		*dptr++ = 0;
+	}
+
+	*dptr++ = cmdflags;
+	*dptr++ = 0;
+
+	if (!nr_route_frame(skbn, NULL))
+		kfree_skb(skbn);
+}
+
+void nr_disconnect(struct sock *sk, int reason)
+{
+	nr_stop_t1timer(sk);
+	nr_stop_t2timer(sk);
+	nr_stop_t4timer(sk);
+	nr_stop_idletimer(sk);
+
+	nr_clear_queues(sk);
+
+	nr_sk(sk)->state = NR_STATE_0;
+
+	sk->sk_state     = TCP_CLOSE;
+	sk->sk_err       = reason;
+	sk->sk_shutdown |= SEND_SHUTDOWN;
+
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		sk->sk_state_change(sk);
+		sock_set_flag(sk, SOCK_DEAD);
+	}
+}
diff --git a/net/netrom/nr_timer.c b/net/netrom/nr_timer.c
new file mode 100644
index 000000000..4e7c968cd
--- /dev/null
+++ b/net/netrom/nr_timer.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ * Copyright (C) 2002 Ralf Baechle DO1GRB (ralf@gnu.org)
+ */
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/jiffies.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <linux/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/netrom.h>
+
+static void nr_heartbeat_expiry(struct timer_list *);
+static void nr_t1timer_expiry(struct timer_list *);
+static void nr_t2timer_expiry(struct timer_list *);
+static void nr_t4timer_expiry(struct timer_list *);
+static void nr_idletimer_expiry(struct timer_list *);
+
+void nr_init_timers(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+
+	timer_setup(&nr->t1timer, nr_t1timer_expiry, 0);
+	timer_setup(&nr->t2timer, nr_t2timer_expiry, 0);
+	timer_setup(&nr->t4timer, nr_t4timer_expiry, 0);
+	timer_setup(&nr->idletimer, nr_idletimer_expiry, 0);
+
+	/* initialized by sock_init_data */
+	sk->sk_timer.function = nr_heartbeat_expiry;
+}
+
+void nr_start_t1timer(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+
+	sk_reset_timer(sk, &nr->t1timer, jiffies + nr->t1);
+}
+
+void nr_start_t2timer(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+
+	sk_reset_timer(sk, &nr->t2timer, jiffies + nr->t2);
+}
+
+void nr_start_t4timer(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+
+	sk_reset_timer(sk, &nr->t4timer, jiffies + nr->t4);
+}
+
+void nr_start_idletimer(struct sock *sk)
+{
+	struct nr_sock *nr = nr_sk(sk);
+
+	if (nr->idle > 0)
+		sk_reset_timer(sk, &nr->idletimer, jiffies + nr->idle);
+}
+
+void nr_start_heartbeat(struct sock *sk)
+{
+	sk_reset_timer(sk, &sk->sk_timer, jiffies + 5 * HZ);
+}
+
+void nr_stop_t1timer(struct sock *sk)
+{
+	sk_stop_timer(sk, &nr_sk(sk)->t1timer);
+}
+
+void nr_stop_t2timer(struct sock *sk)
+{
+	sk_stop_timer(sk, &nr_sk(sk)->t2timer);
+}
+
+void nr_stop_t4timer(struct sock *sk)
+{
+	sk_stop_timer(sk, &nr_sk(sk)->t4timer);
+}
+
+void nr_stop_idletimer(struct sock *sk)
+{
+	sk_stop_timer(sk, &nr_sk(sk)->idletimer);
+}
+
+void nr_stop_heartbeat(struct sock *sk)
+{
+	sk_stop_timer(sk, &sk->sk_timer);
+}
+
+int nr_t1timer_running(struct sock *sk)
+{
+	return timer_pending(&nr_sk(sk)->t1timer);
+}
+
+static void nr_heartbeat_expiry(struct timer_list *t)
+{
+	struct sock *sk = from_timer(sk, t, sk_timer);
+	struct nr_sock *nr = nr_sk(sk);
+
+	bh_lock_sock(sk);
+	switch (nr->state) {
+	case NR_STATE_0:
+		/* Magic here: If we listen() and a new link dies before it
+		   is accepted() it isn't 'dead' so doesn't get removed. */
+		if (sock_flag(sk, SOCK_DESTROY) ||
+		    (sk->sk_state == TCP_LISTEN && sock_flag(sk, SOCK_DEAD))) {
+			sock_hold(sk);
+			bh_unlock_sock(sk);
+			nr_destroy_socket(sk);
+			goto out;
+		}
+		break;
+
+	case NR_STATE_3:
+		/*
+		 * Check for the state of the receive buffer.
+		 */
+		if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf / 2) &&
+		    (nr->condition & NR_COND_OWN_RX_BUSY)) {
+			nr->condition &= ~NR_COND_OWN_RX_BUSY;
+			nr->condition &= ~NR_COND_ACK_PENDING;
+			nr->vl         = nr->vr;
+			nr_write_internal(sk, NR_INFOACK);
+			break;
+		}
+		break;
+	}
+
+	nr_start_heartbeat(sk);
+	bh_unlock_sock(sk);
+out:
+	sock_put(sk);
+}
+
+static void nr_t2timer_expiry(struct timer_list *t)
+{
+	struct nr_sock *nr = from_timer(nr, t, t2timer);
+	struct sock *sk = &nr->sock;
+
+	bh_lock_sock(sk);
+	if (nr->condition & NR_COND_ACK_PENDING) {
+		nr->condition &= ~NR_COND_ACK_PENDING;
+		nr_enquiry_response(sk);
+	}
+	bh_unlock_sock(sk);
+	sock_put(sk);
+}
+
+static void nr_t4timer_expiry(struct timer_list *t)
+{
+	struct nr_sock *nr = from_timer(nr, t, t4timer);
+	struct sock *sk = &nr->sock;
+
+	bh_lock_sock(sk);
+	nr_sk(sk)->condition &= ~NR_COND_PEER_RX_BUSY;
+	bh_unlock_sock(sk);
+	sock_put(sk);
+}
+
+static void nr_idletimer_expiry(struct timer_list *t)
+{
+	struct nr_sock *nr = from_timer(nr, t, idletimer);
+	struct sock *sk = &nr->sock;
+
+	bh_lock_sock(sk);
+
+	nr_clear_queues(sk);
+
+	nr->n2count = 0;
+	nr_write_internal(sk, NR_DISCREQ);
+	nr->state = NR_STATE_2;
+
+	nr_start_t1timer(sk);
+	nr_stop_t2timer(sk);
+	nr_stop_t4timer(sk);
+
+	sk->sk_state     = TCP_CLOSE;
+	sk->sk_err       = 0;
+	sk->sk_shutdown |= SEND_SHUTDOWN;
+
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		sk->sk_state_change(sk);
+		sock_set_flag(sk, SOCK_DEAD);
+	}
+	bh_unlock_sock(sk);
+	sock_put(sk);
+}
+
+static void nr_t1timer_expiry(struct timer_list *t)
+{
+	struct nr_sock *nr = from_timer(nr, t, t1timer);
+	struct sock *sk = &nr->sock;
+
+	bh_lock_sock(sk);
+	switch (nr->state) {
+	case NR_STATE_1:
+		if (nr->n2count == nr->n2) {
+			nr_disconnect(sk, ETIMEDOUT);
+			goto out;
+		} else {
+			nr->n2count++;
+			nr_write_internal(sk, NR_CONNREQ);
+		}
+		break;
+
+	case NR_STATE_2:
+		if (nr->n2count == nr->n2) {
+			nr_disconnect(sk, ETIMEDOUT);
+			goto out;
+		} else {
+			nr->n2count++;
+			nr_write_internal(sk, NR_DISCREQ);
+		}
+		break;
+
+	case NR_STATE_3:
+		if (nr->n2count == nr->n2) {
+			nr_disconnect(sk, ETIMEDOUT);
+			goto out;
+		} else {
+			nr->n2count++;
+			nr_requeue_frames(sk);
+		}
+		break;
+	}
+
+	nr_start_t1timer(sk);
+out:
+	bh_unlock_sock(sk);
+	sock_put(sk);
+}
diff --git a/net/netrom/sysctl_net_netrom.c b/net/netrom/sysctl_net_netrom.c
new file mode 100644
index 000000000..79fb2d3f4
--- /dev/null
+++ b/net/netrom/sysctl_net_netrom.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright (C) 1996 Mike Shaver (shaver@zeroknowledge.com)
+ */
+#include <linux/mm.h>
+#include <linux/sysctl.h>
+#include <linux/init.h>
+#include <net/ax25.h>
+#include <net/netrom.h>
+
+/*
+ *	Values taken from NET/ROM documentation.
+ */
+static int min_quality[] = {0}, max_quality[] = {255};
+static int min_obs[]     = {0}, max_obs[]     = {255};
+static int min_ttl[]     = {0}, max_ttl[]     = {255};
+static int min_t1[]      = {5 * HZ};
+static int max_t1[]      = {600 * HZ};
+static int min_n2[]      = {2}, max_n2[]      = {127};
+static int min_t2[]      = {1 * HZ};
+static int max_t2[]      = {60 * HZ};
+static int min_t4[]      = {1 * HZ};
+static int max_t4[]      = {1000 * HZ};
+static int min_window[]  = {1}, max_window[]  = {127};
+static int min_idle[]    = {0 * HZ};
+static int max_idle[]    = {65535 * HZ};
+static int min_route[]   = {0}, max_route[]   = {1};
+static int min_fails[]   = {1}, max_fails[]   = {10};
+static int min_reset[]   = {0}, max_reset[]   = {1};
+
+static struct ctl_table_header *nr_table_header;
+
+static struct ctl_table nr_table[] = {
+	{
+		.procname	= "default_path_quality",
+		.data		= &sysctl_netrom_default_path_quality,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_quality,
+		.extra2		= &max_quality
+	},
+	{
+		.procname	= "obsolescence_count_initialiser",
+		.data		= &sysctl_netrom_obsolescence_count_initialiser,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_obs,
+		.extra2		= &max_obs
+	},
+	{
+		.procname	= "network_ttl_initialiser",
+		.data		= &sysctl_netrom_network_ttl_initialiser,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_ttl,
+		.extra2		= &max_ttl
+	},
+	{
+		.procname	= "transport_timeout",
+		.data		= &sysctl_netrom_transport_timeout,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_t1,
+		.extra2		= &max_t1
+	},
+	{
+		.procname	= "transport_maximum_tries",
+		.data		= &sysctl_netrom_transport_maximum_tries,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_n2,
+		.extra2		= &max_n2
+	},
+	{
+		.procname	= "transport_acknowledge_delay",
+		.data		= &sysctl_netrom_transport_acknowledge_delay,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_t2,
+		.extra2		= &max_t2
+	},
+	{
+		.procname	= "transport_busy_delay",
+		.data		= &sysctl_netrom_transport_busy_delay,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_t4,
+		.extra2		= &max_t4
+	},
+	{
+		.procname	= "transport_requested_window_size",
+		.data		= &sysctl_netrom_transport_requested_window_size,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_window,
+		.extra2		= &max_window
+	},
+	{
+		.procname	= "transport_no_activity_timeout",
+		.data		= &sysctl_netrom_transport_no_activity_timeout,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_idle,
+		.extra2		= &max_idle
+	},
+	{
+		.procname	= "routing_control",
+		.data		= &sysctl_netrom_routing_control,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_route,
+		.extra2		= &max_route
+	},
+	{
+		.procname	= "link_fails_count",
+		.data		= &sysctl_netrom_link_fails_count,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_fails,
+		.extra2		= &max_fails
+	},
+	{
+		.procname	= "reset",
+		.data		= &sysctl_netrom_reset_circuit,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &min_reset,
+		.extra2		= &max_reset
+	},
+	{ }
+};
+
+int __init nr_register_sysctl(void)
+{
+	nr_table_header = register_net_sysctl(&init_net, "net/netrom", nr_table);
+	if (!nr_table_header)
+		return -ENOMEM;
+	return 0;
+}
+
+void nr_unregister_sysctl(void)
+{
+	unregister_net_sysctl_table(nr_table_header);
+}