x25_route.c

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/*
 *  X.25 Packet Layer release 002
 *
 *  This is ALPHA test software. This code may break your machine,
 *  randomly fail to work with new releases, misbehave and/or generally
 *  screw up. It might even work.
 *
 *  This code REQUIRES 2.1.15 or higher
 *
 *  This module:
 *      This module 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.
 *
 *  History
 *  X.25 001    Jonathan Naylor Started coding.
 */

#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <net/x25.h>

LIST_HEAD(x25_route_list);
DEFINE_RWLOCK(x25_route_list_lock);

/*
 *  Add a new route.
 */
static int x25_add_route(struct x25_address *address, unsigned int sigdigits,
             struct net_device *dev)
{
    struct x25_route *rt;
    struct list_head *entry;
    int rc = -EINVAL;

    write_lock_bh(&x25_route_list_lock);

    list_for_each(entry, &x25_route_list) {
        rt = list_entry(entry, struct x25_route, node);

        if (!memcmp(&rt->address, address, sigdigits) &&
            rt->sigdigits == sigdigits)
            goto out;
    }

    rt = kmalloc(sizeof(*rt), GFP_ATOMIC);
    rc = -ENOMEM;
    if (!rt)
        goto out;

    strcpy(rt->address.x25_addr, "000000000000000");
    memcpy(rt->address.x25_addr, address->x25_addr, sigdigits);

    rt->sigdigits = sigdigits;
    rt->dev       = dev;
    atomic_set(&rt->refcnt, 1);

    list_add(&rt->node, &x25_route_list);
    rc = 0;
out:
    write_unlock_bh(&x25_route_list_lock);
    return rc;
}

static void __x25_remove_route(struct x25_route *rt)
{
    if (rt->node.next) {
        list_del(&rt->node);
        x25_route_put(rt);
    }
}

static int x25_del_route(struct x25_address *address, unsigned int sigdigits,
             struct net_device *dev)
{
    struct x25_route *rt;
    struct list_head *entry;
    int rc = -EINVAL;

    write_lock_bh(&x25_route_list_lock);

    list_for_each(entry, &x25_route_list) {
        rt = list_entry(entry, struct x25_route, node);

        if (!memcmp(&rt->address, address, sigdigits) &&
            rt->sigdigits == sigdigits && rt->dev == dev) {
            __x25_remove_route(rt);
            rc = 0;
            break;
        }
    }

    write_unlock_bh(&x25_route_list_lock);
    return rc;
}

/*
 *  A device has been removed, remove its routes.
 */
void x25_route_device_down(struct net_device *dev)
{
    struct x25_route *rt;
    struct list_head *entry, *tmp;

    write_lock_bh(&x25_route_list_lock);

    list_for_each_safe(entry, tmp, &x25_route_list) {
        rt = list_entry(entry, struct x25_route, node);

        if (rt->dev == dev)
            __x25_remove_route(rt);
    }
    write_unlock_bh(&x25_route_list_lock);

    /* Remove any related forwarding */
    x25_clear_forward_by_dev(dev);
}

/*
 *  Check that the device given is a valid X.25 interface that is "up".
 */
struct net_device *x25_dev_get(char *devname)
{
    struct net_device *dev = dev_get_by_name(&init_net, devname);

    if (dev &&
        (!(dev->flags & IFF_UP) || (dev->type != ARPHRD_X25
#if IS_ENABLED(CONFIG_LLC)
                    && dev->type != ARPHRD_ETHER
#endif
                    ))){
        dev_put(dev);
        dev = NULL;
    }

    return dev;
}

struct x25_route *x25_get_route(struct x25_address *addr)
{
    struct x25_route *rt, *use = NULL;
    struct list_head *entry;

    read_lock_bh(&x25_route_list_lock);

    list_for_each(entry, &x25_route_list) {
        rt = list_entry(entry, struct x25_route, node);

        if (!memcmp(&rt->address, addr, rt->sigdigits)) {
            if (!use)
                use = rt;
            else if (rt->sigdigits > use->sigdigits)
                use = rt;
        }
    }

    if (use)
        x25_route_hold(use);

    read_unlock_bh(&x25_route_list_lock);
    return use;
}

/*
 *  Handle the ioctls that control the routing functions.
 */
int x25_route_ioctl(unsigned int cmd, void __user *arg)
{
    struct x25_route_struct rt;
    struct net_device *dev;
    int rc = -EINVAL;

    if (cmd != SIOCADDRT && cmd != SIOCDELRT)
        goto out;

    rc = -EFAULT;
    if (copy_from_user(&rt, arg, sizeof(rt)))
        goto out;

    rc = -EINVAL;
    if (rt.sigdigits > 15)
        goto out;

    dev = x25_dev_get(rt.device);
    if (!dev)
        goto out;

    if (cmd == SIOCADDRT)
        rc = x25_add_route(&rt.address, rt.sigdigits, dev);
    else
        rc = x25_del_route(&rt.address, rt.sigdigits, dev);
    dev_put(dev);
out:
    return rc;
}

/*
 *  Release all memory associated with X.25 routing structures.
 */
void __exit x25_route_free(void)
{
    struct x25_route *rt;
    struct list_head *entry, *tmp;

    write_lock_bh(&x25_route_list_lock);
    list_for_each_safe(entry, tmp, &x25_route_list) {
        rt = list_entry(entry, struct x25_route, node);
        __x25_remove_route(rt);
    }
    write_unlock_bh(&x25_route_list_lock);
}