ax25_route.c

Go to the documentation of this file.

/*
 * 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 (C) Alan Cox GW4PTS ([email protected])
 * Copyright (C) Jonathan Naylor G4KLX ([email protected])
 * Copyright (C) Steven Whitehouse GW7RRM ([email protected])
 * Copyright (C) Joerg Reuter DL1BKE ([email protected])
 * Copyright (C) Hans-Joachim Hetscher DD8NE ([email protected])
 * Copyright (C) Frederic Rible F1OAT ([email protected])
 */

#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/timer.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sched.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/if_arp.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <net/sock.h>
#include <asm/uaccess.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/export.h>

static ax25_route *ax25_route_list;
static DEFINE_RWLOCK(ax25_route_lock);

void ax25_rt_device_down(struct net_device *dev)
{
    ax25_route *s, *t, *ax25_rt;

    write_lock_bh(&ax25_route_lock);
    ax25_rt = ax25_route_list;
    while (ax25_rt != NULL) {
        s       = ax25_rt;
        ax25_rt = ax25_rt->next;

        if (s->dev == dev) {
            if (ax25_route_list == s) {
                ax25_route_list = s->next;
                kfree(s->digipeat);
                kfree(s);
            } else {
                for (t = ax25_route_list; t != NULL; t = t->next) {
                    if (t->next == s) {
                        t->next = s->next;
                        kfree(s->digipeat);
                        kfree(s);
                        break;
                    }
                }
            }
        }
    }
    write_unlock_bh(&ax25_route_lock);
}

static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
{
    ax25_route *ax25_rt;
    ax25_dev *ax25_dev;
    int i;

    if ((ax25_dev = ax25_addr_ax25dev(&route->port_addr)) == NULL)
        return -EINVAL;
    if (route->digi_count > AX25_MAX_DIGIS)
        return -EINVAL;

    write_lock_bh(&ax25_route_lock);

    ax25_rt = ax25_route_list;
    while (ax25_rt != NULL) {
        if (ax25cmp(&ax25_rt->callsign, &route->dest_addr) == 0 &&
                ax25_rt->dev == ax25_dev->dev) {
            kfree(ax25_rt->digipeat);
            ax25_rt->digipeat = NULL;
            if (route->digi_count != 0) {
                if ((ax25_rt->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
                    write_unlock_bh(&ax25_route_lock);
                    return -ENOMEM;
                }
                ax25_rt->digipeat->lastrepeat = -1;
                ax25_rt->digipeat->ndigi      = route->digi_count;
                for (i = 0; i < route->digi_count; i++) {
                    ax25_rt->digipeat->repeated[i] = 0;
                    ax25_rt->digipeat->calls[i]    = route->digi_addr[i];
                }
            }
            write_unlock_bh(&ax25_route_lock);
            return 0;
        }
        ax25_rt = ax25_rt->next;
    }

    if ((ax25_rt = kmalloc(sizeof(ax25_route), GFP_ATOMIC)) == NULL) {
        write_unlock_bh(&ax25_route_lock);
        return -ENOMEM;
    }

    atomic_set(&ax25_rt->refcount, 1);
    ax25_rt->callsign     = route->dest_addr;
    ax25_rt->dev          = ax25_dev->dev;
    ax25_rt->digipeat     = NULL;
    ax25_rt->ip_mode      = ' ';
    if (route->digi_count != 0) {
        if ((ax25_rt->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
            write_unlock_bh(&ax25_route_lock);
            kfree(ax25_rt);
            return -ENOMEM;
        }
        ax25_rt->digipeat->lastrepeat = -1;
        ax25_rt->digipeat->ndigi      = route->digi_count;
        for (i = 0; i < route->digi_count; i++) {
            ax25_rt->digipeat->repeated[i] = 0;
            ax25_rt->digipeat->calls[i]    = route->digi_addr[i];
        }
    }
    ax25_rt->next   = ax25_route_list;
    ax25_route_list = ax25_rt;
    write_unlock_bh(&ax25_route_lock);

    return 0;
}

void __ax25_put_route(ax25_route *ax25_rt)
{
    kfree(ax25_rt->digipeat);
    kfree(ax25_rt);
}

static int ax25_rt_del(struct ax25_routes_struct *route)
{
    ax25_route *s, *t, *ax25_rt;
    ax25_dev *ax25_dev;

    if ((ax25_dev = ax25_addr_ax25dev(&route->port_addr)) == NULL)
        return -EINVAL;

    write_lock_bh(&ax25_route_lock);

    ax25_rt = ax25_route_list;
    while (ax25_rt != NULL) {
        s       = ax25_rt;
        ax25_rt = ax25_rt->next;
        if (s->dev == ax25_dev->dev &&
            ax25cmp(&route->dest_addr, &s->callsign) == 0) {
            if (ax25_route_list == s) {
                ax25_route_list = s->next;
                ax25_put_route(s);
            } else {
                for (t = ax25_route_list; t != NULL; t = t->next) {
                    if (t->next == s) {
                        t->next = s->next;
                        ax25_put_route(s);
                        break;
                    }
                }
            }
        }
    }
    write_unlock_bh(&ax25_route_lock);

    return 0;
}

static int ax25_rt_opt(struct ax25_route_opt_struct *rt_option)
{
    ax25_route *ax25_rt;
    ax25_dev *ax25_dev;
    int err = 0;

    if ((ax25_dev = ax25_addr_ax25dev(&rt_option->port_addr)) == NULL)
        return -EINVAL;

    write_lock_bh(&ax25_route_lock);

    ax25_rt = ax25_route_list;
    while (ax25_rt != NULL) {
        if (ax25_rt->dev == ax25_dev->dev &&
            ax25cmp(&rt_option->dest_addr, &ax25_rt->callsign) == 0) {
            switch (rt_option->cmd) {
            case AX25_SET_RT_IPMODE:
                switch (rt_option->arg) {
                case ' ':
                case 'D':
                case 'V':
                    ax25_rt->ip_mode = rt_option->arg;
                    break;
                default:
                    err = -EINVAL;
                    goto out;
                }
                break;
            default:
                err = -EINVAL;
                goto out;
            }
        }
        ax25_rt = ax25_rt->next;
    }

out:
    write_unlock_bh(&ax25_route_lock);
    return err;
}

int ax25_rt_ioctl(unsigned int cmd, void __user *arg)
{
    struct ax25_route_opt_struct rt_option;
    struct ax25_routes_struct route;

    switch (cmd) {
    case SIOCADDRT:
        if (copy_from_user(&route, arg, sizeof(route)))
            return -EFAULT;
        return ax25_rt_add(&route);

    case SIOCDELRT:
        if (copy_from_user(&route, arg, sizeof(route)))
            return -EFAULT;
        return ax25_rt_del(&route);

    case SIOCAX25OPTRT:
        if (copy_from_user(&rt_option, arg, sizeof(rt_option)))
            return -EFAULT;
        return ax25_rt_opt(&rt_option);

    default:
        return -EINVAL;
    }
}

#ifdef CONFIG_PROC_FS

static void *ax25_rt_seq_start(struct seq_file *seq, loff_t *pos)
    __acquires(ax25_route_lock)
{
    struct ax25_route *ax25_rt;
    int i = 1;

    read_lock(&ax25_route_lock);
    if (*pos == 0)
        return SEQ_START_TOKEN;

    for (ax25_rt = ax25_route_list; ax25_rt != NULL; ax25_rt = ax25_rt->next) {
        if (i == *pos)
            return ax25_rt;
        ++i;
    }

    return NULL;
}

static void *ax25_rt_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    ++*pos;
    return (v == SEQ_START_TOKEN) ? ax25_route_list :
        ((struct ax25_route *) v)->next;
}

static void ax25_rt_seq_stop(struct seq_file *seq, void *v)
    __releases(ax25_route_lock)
{
    read_unlock(&ax25_route_lock);
}

static int ax25_rt_seq_show(struct seq_file *seq, void *v)
{
    char buf[11];

    if (v == SEQ_START_TOKEN)
        seq_puts(seq, "callsign  dev  mode digipeaters\n");
    else {
        struct ax25_route *ax25_rt = v;
        const char *callsign;
        int i;

        if (ax25cmp(&ax25_rt->callsign, &null_ax25_address) == 0)
            callsign = "default";
        else
            callsign = ax2asc(buf, &ax25_rt->callsign);

        seq_printf(seq, "%-9s %-4s",
            callsign,
            ax25_rt->dev ? ax25_rt->dev->name : "???");

        switch (ax25_rt->ip_mode) {
        case 'V':
            seq_puts(seq, "   vc");
            break;
        case 'D':
            seq_puts(seq, "   dg");
            break;
        default:
            seq_puts(seq, "    *");
            break;
        }

        if (ax25_rt->digipeat != NULL)
            for (i = 0; i < ax25_rt->digipeat->ndigi; i++)
                seq_printf(seq, " %s",
                     ax2asc(buf, &ax25_rt->digipeat->calls[i]));

        seq_puts(seq, "\n");
    }
    return 0;
}

static const struct seq_operations ax25_rt_seqops = {
    .start = ax25_rt_seq_start,
    .next = ax25_rt_seq_next,
    .stop = ax25_rt_seq_stop,
    .show = ax25_rt_seq_show,
};

static int ax25_rt_info_open(struct inode *inode, struct file *file)
{
    return seq_open(file, &ax25_rt_seqops);
}

const struct file_operations ax25_route_fops = {
    .owner = THIS_MODULE,
    .open = ax25_rt_info_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = seq_release,
};

#endif

/*
 *  Find AX.25 route
 *
 *  Only routes with a reference count of zero can be destroyed.
 */
ax25_route *ax25_get_route(ax25_address *addr, struct net_device *dev)
{
    ax25_route *ax25_spe_rt = NULL;
    ax25_route *ax25_def_rt = NULL;
    ax25_route *ax25_rt;

    read_lock(&ax25_route_lock);
    /*
     *  Bind to the physical interface we heard them on, or the default
     *  route if none is found;
     */
    for (ax25_rt = ax25_route_list; ax25_rt != NULL; ax25_rt = ax25_rt->next) {
        if (dev == NULL) {
            if (ax25cmp(&ax25_rt->callsign, addr) == 0 && ax25_rt->dev != NULL)
                ax25_spe_rt = ax25_rt;
            if (ax25cmp(&ax25_rt->callsign, &null_ax25_address) == 0 && ax25_rt->dev != NULL)
                ax25_def_rt = ax25_rt;
        } else {
            if (ax25cmp(&ax25_rt->callsign, addr) == 0 && ax25_rt->dev == dev)
                ax25_spe_rt = ax25_rt;
            if (ax25cmp(&ax25_rt->callsign, &null_ax25_address) == 0 && ax25_rt->dev == dev)
                ax25_def_rt = ax25_rt;
        }
    }

    ax25_rt = ax25_def_rt;
    if (ax25_spe_rt != NULL)
        ax25_rt = ax25_spe_rt;

    if (ax25_rt != NULL)
        ax25_hold_route(ax25_rt);

    read_unlock(&ax25_route_lock);

    return ax25_rt;
}

/*
 *  Adjust path: If you specify a default route and want to connect
 *      a target on the digipeater path but w/o having a special route
 *  set before, the path has to be truncated from your target on.
 */
static inline void ax25_adjust_path(ax25_address *addr, ax25_digi *digipeat)
{
    int k;

    for (k = 0; k < digipeat->ndigi; k++) {
        if (ax25cmp(addr, &digipeat->calls[k]) == 0)
            break;
    }

    digipeat->ndigi = k;
}


/*
 *  Find which interface to use.
 */
int ax25_rt_autobind(ax25_cb *ax25, ax25_address *addr)
{
    ax25_uid_assoc *user;
    ax25_route *ax25_rt;
    int err = 0;

    if ((ax25_rt = ax25_get_route(addr, NULL)) == NULL)
        return -EHOSTUNREACH;

    if ((ax25->ax25_dev = ax25_dev_ax25dev(ax25_rt->dev)) == NULL) {
        err = -EHOSTUNREACH;
        goto put;
    }

    user = ax25_findbyuid(current_euid());
    if (user) {
        ax25->source_addr = user->call;
        ax25_uid_put(user);
    } else {
        if (ax25_uid_policy && !capable(CAP_NET_BIND_SERVICE)) {
            err = -EPERM;
            goto put;
        }
        ax25->source_addr = *(ax25_address *)ax25->ax25_dev->dev->dev_addr;
    }

    if (ax25_rt->digipeat != NULL) {
        ax25->digipeat = kmemdup(ax25_rt->digipeat, sizeof(ax25_digi),
                     GFP_ATOMIC);
        if (ax25->digipeat == NULL) {
            err = -ENOMEM;
            goto put;
        }
        ax25_adjust_path(addr, ax25->digipeat);
    }

    if (ax25->sk != NULL) {
        bh_lock_sock(ax25->sk);
        sock_reset_flag(ax25->sk, SOCK_ZAPPED);
        bh_unlock_sock(ax25->sk);
    }

put:
    ax25_put_route(ax25_rt);

    return err;
}

struct sk_buff *ax25_rt_build_path(struct sk_buff *skb, ax25_address *src,
    ax25_address *dest, ax25_digi *digi)
{
    struct sk_buff *skbn;
    unsigned char *bp;
    int len;

    len = digi->ndigi * AX25_ADDR_LEN;

    if (skb_headroom(skb) < len) {
        if ((skbn = skb_realloc_headroom(skb, len)) == NULL) {
            printk(KERN_CRIT "AX.25: ax25_dg_build_path - out of memory\n");
            return NULL;
        }

        if (skb->sk != NULL)
            skb_set_owner_w(skbn, skb->sk);

        consume_skb(skb);

        skb = skbn;
    }

    bp = skb_push(skb, len);

    ax25_addr_build(bp, src, dest, digi, AX25_COMMAND, AX25_MODULUS);

    return skb;
}

/*
 *  Free all memory associated with routing structures.
 */
void __exit ax25_rt_free(void)
{
    ax25_route *s, *ax25_rt = ax25_route_list;

    write_lock_bh(&ax25_route_lock);
    while (ax25_rt != NULL) {
        s       = ax25_rt;
        ax25_rt = ax25_rt->next;

        kfree(s->digipeat);
        kfree(s);
    }
    write_unlock_bh(&ax25_route_lock);
}