dlci.c

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/*
 * DLCI     Implementation of Frame Relay protocol for Linux, according to
 *      RFC 1490.  This generic device provides en/decapsulation for an
 *      underlying hardware driver.  Routes & IPs are assigned to these
 *      interfaces.  Requires 'dlcicfg' program to create usable 
 *      interfaces, the initial one, 'dlci' is for IOCTL use only.
 *
 * Version: @(#)dlci.c  0.35    4 Jan 1997
 *
 * Author:  Mike McLagan <[email protected]>
 *
 * Changes:
 *
 *      0.15    Mike Mclagan    Packet freeing, bug in kmalloc call
 *                  DLCI_RET handling
 *      0.20    Mike McLagan    More conservative on which packets
 *                  are returned for retry and which are
 *                  are dropped.  If DLCI_RET_DROP is
 *                  returned from the FRAD, the packet is
 *                  sent back to Linux for re-transmission
 *      0.25    Mike McLagan    Converted to use SIOC IOCTL calls
 *      0.30    Jim Freeman Fixed to allow IPX traffic
 *      0.35    Michael Elizabeth   Fixed incorrect memcpy_fromfs
 *
 *      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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/in.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/if_frad.h>
#include <linux/bitops.h>

#include <net/sock.h>

#include <asm/io.h>
#include <asm/dma.h>
#include <asm/uaccess.h>

static const char version[] = "DLCI driver v0.35, 4 Jan 1997, [email protected]";

static LIST_HEAD(dlci_devs);

static void dlci_setup(struct net_device *);

/* 
 * these encapsulate the RFC 1490 requirements as well as 
 * deal with packet transmission and reception, working with
 * the upper network layers 
 */

static int dlci_header(struct sk_buff *skb, struct net_device *dev, 
               unsigned short type, const void *daddr,
               const void *saddr, unsigned len)
{
    struct frhdr        hdr;
    struct dlci_local   *dlp;
    unsigned int        hlen;
    char            *dest;

    dlp = netdev_priv(dev);

    hdr.control = FRAD_I_UI;
    switch (type)
    {
        case ETH_P_IP:
            hdr.IP_NLPID = FRAD_P_IP;
            hlen = sizeof(hdr.control) + sizeof(hdr.IP_NLPID);
            break;

        /* feel free to add other types, if necessary */

        default:
            hdr.pad = FRAD_P_PADDING;
            hdr.NLPID = FRAD_P_SNAP;
            memset(hdr.OUI, 0, sizeof(hdr.OUI));
            hdr.PID = htons(type);
            hlen = sizeof(hdr);
            break;
    }

    dest = skb_push(skb, hlen);
    if (!dest)
        return 0;

    memcpy(dest, &hdr, hlen);

    return hlen;
}

static void dlci_receive(struct sk_buff *skb, struct net_device *dev)
{
    struct dlci_local *dlp;
    struct frhdr        *hdr;
    int                 process, header;

    dlp = netdev_priv(dev);
    if (!pskb_may_pull(skb, sizeof(*hdr))) {
        netdev_notice(dev, "invalid data no header\n");
        dev->stats.rx_errors++;
        kfree_skb(skb);
        return;
    }

    hdr = (struct frhdr *) skb->data;
    process = 0;
    header = 0;
    skb->dev = dev;

    if (hdr->control != FRAD_I_UI)
    {
        netdev_notice(dev, "Invalid header flag 0x%02X\n",
                  hdr->control);
        dev->stats.rx_errors++;
    }
    else
        switch (hdr->IP_NLPID)
        {
            case FRAD_P_PADDING:
                if (hdr->NLPID != FRAD_P_SNAP)
                {
                    netdev_notice(dev, "Unsupported NLPID 0x%02X\n",
                              hdr->NLPID);
                    dev->stats.rx_errors++;
                    break;
                }
     
                if (hdr->OUI[0] + hdr->OUI[1] + hdr->OUI[2] != 0)
                {
                    netdev_notice(dev, "Unsupported organizationally unique identifier 0x%02X-%02X-%02X\n",
                              hdr->OUI[0],
                              hdr->OUI[1],
                              hdr->OUI[2]);
                    dev->stats.rx_errors++;
                    break;
                }

                /* at this point, it's an EtherType frame */
                header = sizeof(struct frhdr);
                /* Already in network order ! */
                skb->protocol = hdr->PID;
                process = 1;
                break;

            case FRAD_P_IP:
                header = sizeof(hdr->control) + sizeof(hdr->IP_NLPID);
                skb->protocol = htons(ETH_P_IP);
                process = 1;
                break;

            case FRAD_P_SNAP:
            case FRAD_P_Q933:
            case FRAD_P_CLNP:
                netdev_notice(dev, "Unsupported NLPID 0x%02X\n",
                          hdr->pad);
                dev->stats.rx_errors++;
                break;

            default:
                netdev_notice(dev, "Invalid pad byte 0x%02X\n",
                          hdr->pad);
                dev->stats.rx_errors++;
                break;              
        }

    if (process)
    {
        /* we've set up the protocol, so discard the header */
        skb_reset_mac_header(skb);
        skb_pull(skb, header);
        dev->stats.rx_bytes += skb->len;
        netif_rx(skb);
        dev->stats.rx_packets++;
    }
    else
        dev_kfree_skb(skb);
}

static netdev_tx_t dlci_transmit(struct sk_buff *skb, struct net_device *dev)
{
    struct dlci_local *dlp = netdev_priv(dev);

    if (skb)
        dlp->slave->netdev_ops->ndo_start_xmit(skb, dlp->slave);
    return NETDEV_TX_OK;
}

static int dlci_config(struct net_device *dev, struct dlci_conf __user *conf, int get)
{
    struct dlci_conf    config;
    struct dlci_local   *dlp;
    struct frad_local   *flp;
    int         err;

    dlp = netdev_priv(dev);

    flp = netdev_priv(dlp->slave);

    if (!get)
    {
        if (copy_from_user(&config, conf, sizeof(struct dlci_conf)))
            return -EFAULT;
        if (config.flags & ~DLCI_VALID_FLAGS)
            return -EINVAL;
        memcpy(&dlp->config, &config, sizeof(struct dlci_conf));
        dlp->configured = 1;
    }

    err = (*flp->dlci_conf)(dlp->slave, dev, get);
    if (err)
        return err;

    if (get)
    {
        if (copy_to_user(conf, &dlp->config, sizeof(struct dlci_conf)))
            return -EFAULT;
    }

    return 0;
}

static int dlci_dev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
    struct dlci_local *dlp;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    dlp = netdev_priv(dev);

    switch (cmd)
    {
        case DLCI_GET_SLAVE:
            if (!*(short *)(dev->dev_addr))
                return -EINVAL;

            strncpy(ifr->ifr_slave, dlp->slave->name, sizeof(ifr->ifr_slave));
            break;

        case DLCI_GET_CONF:
        case DLCI_SET_CONF:
            if (!*(short *)(dev->dev_addr))
                return -EINVAL;

            return dlci_config(dev, ifr->ifr_data, cmd == DLCI_GET_CONF);
            break;

        default: 
            return -EOPNOTSUPP;
    }
    return 0;
}

static int dlci_change_mtu(struct net_device *dev, int new_mtu)
{
    struct dlci_local *dlp = netdev_priv(dev);

    return dev_set_mtu(dlp->slave, new_mtu);
}

static int dlci_open(struct net_device *dev)
{
    struct dlci_local   *dlp;
    struct frad_local   *flp;
    int         err;

    dlp = netdev_priv(dev);

    if (!*(short *)(dev->dev_addr))
        return -EINVAL;

    if (!netif_running(dlp->slave))
        return -ENOTCONN;

    flp = netdev_priv(dlp->slave);
    err = (*flp->activate)(dlp->slave, dev);
    if (err)
        return err;

    netif_start_queue(dev);

    return 0;
}

static int dlci_close(struct net_device *dev)
{
    struct dlci_local   *dlp;
    struct frad_local   *flp;
    int         err;

    netif_stop_queue(dev);

    dlp = netdev_priv(dev);

    flp = netdev_priv(dlp->slave);
    err = (*flp->deactivate)(dlp->slave, dev);

    return 0;
}

static int dlci_add(struct dlci_add *dlci)
{
    struct net_device   *master, *slave;
    struct dlci_local   *dlp;
    struct frad_local   *flp;
    int         err = -EINVAL;


    /* validate slave device */
    slave = dev_get_by_name(&init_net, dlci->devname);
    if (!slave)
        return -ENODEV;

    if (slave->type != ARPHRD_FRAD || netdev_priv(slave) == NULL)
        goto err1;

    /* create device name */
    master = alloc_netdev( sizeof(struct dlci_local), "dlci%d",
                  dlci_setup);
    if (!master) {
        err = -ENOMEM;
        goto err1;
    }

    /* make sure same slave not already registered */
    rtnl_lock();
    list_for_each_entry(dlp, &dlci_devs, list) {
        if (dlp->slave == slave) {
            err = -EBUSY;
            goto err2;
        }
    }

    *(short *)(master->dev_addr) = dlci->dlci;

    dlp = netdev_priv(master);
    dlp->slave = slave;
    dlp->master = master;

    flp = netdev_priv(slave);
    err = (*flp->assoc)(slave, master);
    if (err < 0)
        goto err2;

    err = register_netdevice(master);
    if (err < 0) 
        goto err2;

    strcpy(dlci->devname, master->name);

    list_add(&dlp->list, &dlci_devs);
    rtnl_unlock();

    return 0;

 err2:
    rtnl_unlock();
    free_netdev(master);
 err1:
    dev_put(slave);
    return err;
}

static int dlci_del(struct dlci_add *dlci)
{
    struct dlci_local   *dlp;
    struct frad_local   *flp;
    struct net_device   *master, *slave;
    int         err;

    /* validate slave device */
    master = __dev_get_by_name(&init_net, dlci->devname);
    if (!master)
        return -ENODEV;

    if (netif_running(master)) {
        return -EBUSY;
    }

    dlp = netdev_priv(master);
    slave = dlp->slave;
    flp = netdev_priv(slave);

    rtnl_lock();
    err = (*flp->deassoc)(slave, master);
    if (!err) {
        list_del(&dlp->list);

        unregister_netdevice(master);

        dev_put(slave);
    }
    rtnl_unlock();

    return err;
}

static int dlci_ioctl(unsigned int cmd, void __user *arg)
{
    struct dlci_add add;
    int err;
    
    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    if (copy_from_user(&add, arg, sizeof(struct dlci_add)))
        return -EFAULT;

    switch (cmd)
    {
        case SIOCADDDLCI:
            err = dlci_add(&add);

            if (!err)
                if (copy_to_user(arg, &add, sizeof(struct dlci_add)))
                    return -EFAULT;
            break;

        case SIOCDELDLCI:
            err = dlci_del(&add);
            break;

        default:
            err = -EINVAL;
    }

    return err;
}

static const struct header_ops dlci_header_ops = {
    .create = dlci_header,
};

static const struct net_device_ops dlci_netdev_ops = {
    .ndo_open   = dlci_open,
    .ndo_stop   = dlci_close,
    .ndo_do_ioctl   = dlci_dev_ioctl,
    .ndo_start_xmit = dlci_transmit,
    .ndo_change_mtu = dlci_change_mtu,
};

static void dlci_setup(struct net_device *dev)
{
    struct dlci_local *dlp = netdev_priv(dev);

    dev->flags      = 0;
    dev->header_ops     = &dlci_header_ops;
    dev->netdev_ops     = &dlci_netdev_ops;
    dev->destructor     = free_netdev;

    dlp->receive        = dlci_receive;

    dev->type       = ARPHRD_DLCI;
    dev->hard_header_len    = sizeof(struct frhdr);
    dev->addr_len       = sizeof(short);

}

/* if slave is unregistering, then cleanup master */
static int dlci_dev_event(struct notifier_block *unused,
              unsigned long event, void *ptr)
{
    struct net_device *dev = (struct net_device *) ptr;

    if (dev_net(dev) != &init_net)
        return NOTIFY_DONE;

    if (event == NETDEV_UNREGISTER) {
        struct dlci_local *dlp;

        list_for_each_entry(dlp, &dlci_devs, list) {
            if (dlp->slave == dev) {
                list_del(&dlp->list);
                unregister_netdevice(dlp->master);
                dev_put(dlp->slave);
                break;
            }
        }
    }
    return NOTIFY_DONE;
}

static struct notifier_block dlci_notifier = {
    .notifier_call = dlci_dev_event,
};

static int __init init_dlci(void)
{
    dlci_ioctl_set(dlci_ioctl);
    register_netdevice_notifier(&dlci_notifier);

    printk("%s.\n", version);

    return 0;
}

static void __exit dlci_exit(void)
{
    struct dlci_local   *dlp, *nxt;
    
    dlci_ioctl_set(NULL);
    unregister_netdevice_notifier(&dlci_notifier);

    rtnl_lock();
    list_for_each_entry_safe(dlp, nxt, &dlci_devs, list) {
        unregister_netdevice(dlp->master);
        dev_put(dlp->slave);
    }
    rtnl_unlock();
}

module_init(init_dlci);
module_exit(dlci_exit);

MODULE_AUTHOR("Mike McLagan");
MODULE_DESCRIPTION("Frame Relay DLCI layer");
MODULE_LICENSE("GPL");