af_netrom.c

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/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Copyright Jonathan Naylor G4KLX ([email protected])
 * Copyright Alan Cox GW4PTS ([email protected])
 * Copyright Darryl Miles G7LED ([email protected])
 */
#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.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 <asm/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;
    struct hlist_node *node;

    spin_lock_bh(&nr_list_lock);
    sk_for_each(s, node, &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 = (struct net_device *)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;
    struct hlist_node *node;

    spin_lock_bh(&nr_list_lock);
    sk_for_each(s, node, &nr_list)
        if (!ax25cmp(&nr_sk(s)->source_addr, addr) &&
            s->sk_state == TCP_LISTEN) {
            bh_lock_sock(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;
    struct hlist_node *node;

    spin_lock_bh(&nr_list_lock);
    sk_for_each(s, node, &nr_list) {
        struct nr_sock *nr = nr_sk(s);

        if (nr->my_index == index && nr->my_id == id) {
            bh_lock_sock(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;
    struct hlist_node *node;

    spin_lock_bh(&nr_list_lock);
    sk_for_each(s, node, &nr_list) {
        struct nr_sock *nr = nr_sk(s);

        if (nr->your_index == index && nr->your_id == id &&
            !ax25cmp(&nr->dest_addr, dest)) {
            bh_lock_sock(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;
            bh_unlock_sock(sk);
        }

        id++;
    }

    return id;
}

/*
 *  Deferred destroy.
 */
void nr_destroy_socket(struct sock *);

/*
 *  Handler for deferred kills.
 */
static void nr_destroy_timer(unsigned long data)
{
    struct sock *sk=(struct sock *)data;
    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,
    char __user *optval, unsigned int optlen)
{
    struct sock *sk = sock->sk;
    struct nr_sock *nr = nr_sk(sk);
    unsigned long opt;

    if (level != SOL_NETROM)
        return -ENOPROTOOPT;

    if (optlen < sizeof(unsigned int))
        return -EINVAL;

    if (get_user(opt, (unsigned int __user *)optval))
        return -EFAULT;

    switch (optname) {
    case NETROM_T1:
        if (opt < 1 || opt > ULONG_MAX / HZ)
            return -EINVAL;
        nr->t1 = opt * HZ;
        return 0;

    case NETROM_T2:
        if (opt < 1 || opt > ULONG_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 > ULONG_MAX / HZ)
            return -EINVAL;
        nr->t4 = opt * HZ;
        return 0;

    case NETROM_IDLE:
        if (opt > ULONG_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 (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);
    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);
    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;
    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;
    }

    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 = (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)
{
    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 *uaddr_len, int peer)
{
    struct full_sockaddr_ax25 *sax = (struct full_sockaddr_ax25 *)uaddr;
    struct sock *sk = sock->sk;
    struct nr_sock *nr = nr_sk(sk);

    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 0;
}

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->sk = NULL;     /* Initially we don't know who it's for */

    /*
     *  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) {
        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);
        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)
            bh_unlock_sock(sk);
        return 0;
    }

    window = skb->data[20];

    skb->sk             = make;
    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, skb->len);

    bh_unlock_sock(sk);

    nr_insert_socket(make);

    nr_start_heartbeat(make);
    nr_start_idletimer(make);

    return 1;
}

static int nr_sendmsg(struct kiocb *iocb, struct socket *sock,
              struct msghdr *msg, size_t len)
{
    struct sock *sk = sock->sk;
    struct nr_sock *nr = nr_sk(sk);
    struct sockaddr_ax25 *usax = (struct sockaddr_ax25 *)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_fromiovec(skb_transport_header(skb), msg->msg_iov, 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 kiocb *iocb, struct socket *sock,
              struct msghdr *msg, size_t size, int flags)
{
    struct sock *sk = sock->sk;
    struct sockaddr_ax25 *sax = (struct sockaddr_ax25 *)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 */
    if ((skb = skb_recv_datagram(sk, flags & ~MSG_DONTWAIT, flags & MSG_DONTWAIT, &er)) == NULL) {
        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_iovec(skb, 0, msg->msg_iov, copied);
    if (er < 0) {
        skb_free_datagram(sk, skb);
        release_sock(sk);
        return er;
    }

    if (sax != NULL) {
        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;
    int ret;

    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 SIOCGSTAMP:
        lock_sock(sk);
        ret = sock_get_timestamp(sk, argp);
        release_sock(sk);
        return ret;

    case SIOCGSTAMPNS:
        lock_sock(sk);
        ret = sock_get_timestampns(sk, argp);
        release_sock(sk);
        return ret;

    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)
{
    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)
{
    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,
};

static int nr_info_open(struct inode *inode, struct file *file)
{
    return seq_open(file, &nr_info_seqops);
}

static const struct file_operations nr_info_fops = {
    .owner = THIS_MODULE,
    .open = nr_info_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = seq_release,
};
#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,
    .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 != 0)
        goto out;

    if (nr_ndevs > 0x7fffffff/sizeof(struct net_device *)) {
        printk(KERN_ERR "NET/ROM: nr_proto_init - nr_ndevs parameter to large\n");
        return -1;
    }

    dev_nr = kzalloc(nr_ndevs * sizeof(struct net_device *), GFP_KERNEL);
    if (dev_nr == NULL) {
        printk(KERN_ERR "NET/ROM: nr_proto_init - unable to allocate device array\n");
        return -1;
    }

    for (i = 0; i < nr_ndevs; i++) {
        char name[IFNAMSIZ];
        struct net_device *dev;

        sprintf(name, "nr%d", i);
        dev = alloc_netdev(0, name, nr_setup);
        if (!dev) {
            printk(KERN_ERR "NET/ROM: nr_proto_init - unable to allocate device structure\n");
            goto fail;
        }

        dev->base_addr = i;
        if (register_netdev(dev)) {
            printk(KERN_ERR "NET/ROM: nr_proto_init - unable to register network device\n");
            free_netdev(dev);
            goto fail;
        }
        nr_set_lockdep_key(dev);
        dev_nr[i] = dev;
    }

    if (sock_register(&nr_family_ops)) {
        printk(KERN_ERR "NET/ROM: nr_proto_init - unable to register socket family\n");
        goto fail;
    }

    register_netdevice_notifier(&nr_dev_notifier);

    ax25_register_pid(&nr_pid);
    ax25_linkfail_register(&nr_linkfail_notifier);

#ifdef CONFIG_SYSCTL
    nr_register_sysctl();
#endif

    nr_loopback_init();

    proc_net_fops_create(&init_net, "nr", S_IRUGO, &nr_info_fops);
    proc_net_fops_create(&init_net, "nr_neigh", S_IRUGO, &nr_neigh_fops);
    proc_net_fops_create(&init_net, "nr_nodes", S_IRUGO, &nr_nodes_fops);
out:
    return rc;
fail:
    while (--i >= 0) {
        unregister_netdev(dev_nr[i]);
        free_netdev(dev_nr[i]);
    }
    kfree(dev_nr);
    proto_unregister(&nr_proto);
    rc = -1;
    goto out;
}

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 <[email protected]>");
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;

    proc_net_remove(&init_net, "nr");
    proc_net_remove(&init_net, "nr_neigh");
    proc_net_remove(&init_net, "nr_nodes");
    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);