path: root/net/netrom/af_netrom.c

// 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 || o