hdlc_cisco.c

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/*
 * Generic HDLC support routines for Linux
 * Cisco HDLC support
 *
 * Copyright (C) 2000 - 2006 Krzysztof Halasa <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License
 * as published by the Free Software Foundation.
 */

#include <linux/errno.h>
#include <linux/hdlc.h>
#include <linux/if_arp.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pkt_sched.h>
#include <linux/poll.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>

#undef DEBUG_HARD_HEADER

#define CISCO_MULTICAST     0x8F    /* Cisco multicast address */
#define CISCO_UNICAST       0x0F    /* Cisco unicast address */
#define CISCO_KEEPALIVE     0x8035  /* Cisco keepalive protocol */
#define CISCO_SYS_INFO      0x2000  /* Cisco interface/system info */
#define CISCO_ADDR_REQ      0   /* Cisco address request */
#define CISCO_ADDR_REPLY    1   /* Cisco address reply */
#define CISCO_KEEPALIVE_REQ 2   /* Cisco keepalive request */


struct hdlc_header {
    u8 address;
    u8 control;
    __be16 protocol;
}__packed;


struct cisco_packet {
    __be32 type;        /* code */
    __be32 par1;
    __be32 par2;
    __be16 rel;     /* reliability */
    __be32 time;
}__packed;
#define CISCO_PACKET_LEN    18
#define CISCO_BIG_PACKET_LEN    20


struct cisco_state {
    cisco_proto settings;

    struct timer_list timer;
    spinlock_t lock;
    unsigned long last_poll;
    int up;
    u32 txseq; /* TX sequence number, 0 = none */
    u32 rxseq; /* RX sequence number */
};


static int cisco_ioctl(struct net_device *dev, struct ifreq *ifr);


static inline struct cisco_state* state(hdlc_device *hdlc)
{
    return (struct cisco_state *)hdlc->state;
}


static int cisco_hard_header(struct sk_buff *skb, struct net_device *dev,
                 u16 type, const void *daddr, const void *saddr,
                 unsigned int len)
{
    struct hdlc_header *data;
#ifdef DEBUG_HARD_HEADER
    printk(KERN_DEBUG "%s: cisco_hard_header called\n", dev->name);
#endif

    skb_push(skb, sizeof(struct hdlc_header));
    data = (struct hdlc_header*)skb->data;
    if (type == CISCO_KEEPALIVE)
        data->address = CISCO_MULTICAST;
    else
        data->address = CISCO_UNICAST;
    data->control = 0;
    data->protocol = htons(type);

    return sizeof(struct hdlc_header);
}



static void cisco_keepalive_send(struct net_device *dev, u32 type,
                 __be32 par1, __be32 par2)
{
    struct sk_buff *skb;
    struct cisco_packet *data;

    skb = dev_alloc_skb(sizeof(struct hdlc_header) +
                sizeof(struct cisco_packet));
    if (!skb) {
        netdev_warn(dev, "Memory squeeze on cisco_keepalive_send()\n");
        return;
    }
    skb_reserve(skb, 4);
    cisco_hard_header(skb, dev, CISCO_KEEPALIVE, NULL, NULL, 0);
    data = (struct cisco_packet*)(skb->data + 4);

    data->type = htonl(type);
    data->par1 = par1;
    data->par2 = par2;
    data->rel = cpu_to_be16(0xFFFF);
    /* we will need do_div here if 1000 % HZ != 0 */
    data->time = htonl((jiffies - INITIAL_JIFFIES) * (1000 / HZ));

    skb_put(skb, sizeof(struct cisco_packet));
    skb->priority = TC_PRIO_CONTROL;
    skb->dev = dev;
    skb_reset_network_header(skb);

    dev_queue_xmit(skb);
}



static __be16 cisco_type_trans(struct sk_buff *skb, struct net_device *dev)
{
    struct hdlc_header *data = (struct hdlc_header*)skb->data;

    if (skb->len < sizeof(struct hdlc_header))
        return cpu_to_be16(ETH_P_HDLC);

    if (data->address != CISCO_MULTICAST &&
        data->address != CISCO_UNICAST)
        return cpu_to_be16(ETH_P_HDLC);

    switch (data->protocol) {
    case cpu_to_be16(ETH_P_IP):
    case cpu_to_be16(ETH_P_IPX):
    case cpu_to_be16(ETH_P_IPV6):
        skb_pull(skb, sizeof(struct hdlc_header));
        return data->protocol;
    default:
        return cpu_to_be16(ETH_P_HDLC);
    }
}


static int cisco_rx(struct sk_buff *skb)
{
    struct net_device *dev = skb->dev;
    hdlc_device *hdlc = dev_to_hdlc(dev);
    struct cisco_state *st = state(hdlc);
    struct hdlc_header *data = (struct hdlc_header*)skb->data;
    struct cisco_packet *cisco_data;
    struct in_device *in_dev;
    __be32 addr, mask;
    u32 ack;

    if (skb->len < sizeof(struct hdlc_header))
        goto rx_error;

    if (data->address != CISCO_MULTICAST &&
        data->address != CISCO_UNICAST)
        goto rx_error;

    switch (ntohs(data->protocol)) {
    case CISCO_SYS_INFO:
        /* Packet is not needed, drop it. */
        dev_kfree_skb_any(skb);
        return NET_RX_SUCCESS;

    case CISCO_KEEPALIVE:
        if ((skb->len != sizeof(struct hdlc_header) +
             CISCO_PACKET_LEN) &&
            (skb->len != sizeof(struct hdlc_header) +
             CISCO_BIG_PACKET_LEN)) {
            netdev_info(dev, "Invalid length of Cisco control packet (%d bytes)\n",
                    skb->len);
            goto rx_error;
        }

        cisco_data = (struct cisco_packet*)(skb->data + sizeof
                            (struct hdlc_header));

        switch (ntohl (cisco_data->type)) {
        case CISCO_ADDR_REQ: /* Stolen from syncppp.c :-) */
            rcu_read_lock();
            in_dev = __in_dev_get_rcu(dev);
            addr = 0;
            mask = ~cpu_to_be32(0); /* is the mask correct? */

            if (in_dev != NULL) {
                struct in_ifaddr **ifap = &in_dev->ifa_list;

                while (*ifap != NULL) {
                    if (strcmp(dev->name,
                           (*ifap)->ifa_label) == 0) {
                        addr = (*ifap)->ifa_local;
                        mask = (*ifap)->ifa_mask;
                        break;
                    }
                    ifap = &(*ifap)->ifa_next;
                }

                cisco_keepalive_send(dev, CISCO_ADDR_REPLY,
                             addr, mask);
            }
            rcu_read_unlock();
            dev_kfree_skb_any(skb);
            return NET_RX_SUCCESS;

        case CISCO_ADDR_REPLY:
            netdev_info(dev, "Unexpected Cisco IP address reply\n");
            goto rx_error;

        case CISCO_KEEPALIVE_REQ:
            spin_lock(&st->lock);
            st->rxseq = ntohl(cisco_data->par1);
            ack = ntohl(cisco_data->par2);
            if (ack && (ack == st->txseq ||
                    /* our current REQ may be in transit */
                    ack == st->txseq - 1)) {
                st->last_poll = jiffies;
                if (!st->up) {
                    u32 sec, min, hrs, days;
                    sec = ntohl(cisco_data->time) / 1000;
                    min = sec / 60; sec -= min * 60;
                    hrs = min / 60; min -= hrs * 60;
                    days = hrs / 24; hrs -= days * 24;
                    netdev_info(dev, "Link up (peer uptime %ud%uh%um%us)\n",
                            days, hrs, min, sec);
                    netif_dormant_off(dev);
                    st->up = 1;
                }
            }
            spin_unlock(&st->lock);

            dev_kfree_skb_any(skb);
            return NET_RX_SUCCESS;
        } /* switch (keepalive type) */
    } /* switch (protocol) */

    netdev_info(dev, "Unsupported protocol %x\n", ntohs(data->protocol));
    dev_kfree_skb_any(skb);
    return NET_RX_DROP;

rx_error:
    dev->stats.rx_errors++; /* Mark error */
    dev_kfree_skb_any(skb);
    return NET_RX_DROP;
}



static void cisco_timer(unsigned long arg)
{
    struct net_device *dev = (struct net_device *)arg;
    hdlc_device *hdlc = dev_to_hdlc(dev);
    struct cisco_state *st = state(hdlc);

    spin_lock(&st->lock);
    if (st->up &&
        time_after(jiffies, st->last_poll + st->settings.timeout * HZ)) {
        st->up = 0;
        netdev_info(dev, "Link down\n");
        netif_dormant_on(dev);
    }

    cisco_keepalive_send(dev, CISCO_KEEPALIVE_REQ, htonl(++st->txseq),
                 htonl(st->rxseq));
    spin_unlock(&st->lock);

    st->timer.expires = jiffies + st->settings.interval * HZ;
    st->timer.function = cisco_timer;
    st->timer.data = arg;
    add_timer(&st->timer);
}



static void cisco_start(struct net_device *dev)
{
    hdlc_device *hdlc = dev_to_hdlc(dev);
    struct cisco_state *st = state(hdlc);
    unsigned long flags;

    spin_lock_irqsave(&st->lock, flags);
    st->up = st->txseq = st->rxseq = 0;
    spin_unlock_irqrestore(&st->lock, flags);

    init_timer(&st->timer);
    st->timer.expires = jiffies + HZ; /* First poll after 1 s */
    st->timer.function = cisco_timer;
    st->timer.data = (unsigned long)dev;
    add_timer(&st->timer);
}



static void cisco_stop(struct net_device *dev)
{
    hdlc_device *hdlc = dev_to_hdlc(dev);
    struct cisco_state *st = state(hdlc);
    unsigned long flags;

    del_timer_sync(&st->timer);

    spin_lock_irqsave(&st->lock, flags);
    netif_dormant_on(dev);
    st->up = st->txseq = 0;
    spin_unlock_irqrestore(&st->lock, flags);
}


static struct hdlc_proto proto = {
    .start      = cisco_start,
    .stop       = cisco_stop,
    .type_trans = cisco_type_trans,
    .ioctl      = cisco_ioctl,
    .netif_rx   = cisco_rx,
    .module     = THIS_MODULE,
};

static const struct header_ops cisco_header_ops = {
    .create = cisco_hard_header,
};

static int cisco_ioctl(struct net_device *dev, struct ifreq *ifr)
{
    cisco_proto __user *cisco_s = ifr->ifr_settings.ifs_ifsu.cisco;
    const size_t size = sizeof(cisco_proto);
    cisco_proto new_settings;
    hdlc_device *hdlc = dev_to_hdlc(dev);
    int result;

    switch (ifr->ifr_settings.type) {
    case IF_GET_PROTO:
        if (dev_to_hdlc(dev)->proto != &proto)
            return -EINVAL;
        ifr->ifr_settings.type = IF_PROTO_CISCO;
        if (ifr->ifr_settings.size < size) {
            ifr->ifr_settings.size = size; /* data size wanted */
            return -ENOBUFS;
        }
        if (copy_to_user(cisco_s, &state(hdlc)->settings, size))
            return -EFAULT;
        return 0;

    case IF_PROTO_CISCO:
        if (!capable(CAP_NET_ADMIN))
            return -EPERM;

        if (dev->flags & IFF_UP)
            return -EBUSY;

        if (copy_from_user(&new_settings, cisco_s, size))
            return -EFAULT;

        if (new_settings.interval < 1 ||
            new_settings.timeout < 2)
            return -EINVAL;

        result = hdlc->attach(dev, ENCODING_NRZ,PARITY_CRC16_PR1_CCITT);
        if (result)
            return result;

        result = attach_hdlc_protocol(dev, &proto,
                          sizeof(struct cisco_state));
        if (result)
            return result;

        memcpy(&state(hdlc)->settings, &new_settings, size);
        spin_lock_init(&state(hdlc)->lock);
        dev->header_ops = &cisco_header_ops;
        dev->type = ARPHRD_CISCO;
        netif_dormant_on(dev);
        return 0;
    }

    return -EINVAL;
}


static int __init mod_init(void)
{
    register_hdlc_protocol(&proto);
    return 0;
}



static void __exit mod_exit(void)
{
    unregister_hdlc_protocol(&proto);
}


module_init(mod_init);
module_exit(mod_exit);

MODULE_AUTHOR("Krzysztof Halasa <[email protected]>");
MODULE_DESCRIPTION("Cisco HDLC protocol support for generic HDLC");
MODULE_LICENSE("GPL v2");