pn_dev.c

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/*
 * File: pn_dev.c
 *
 * Phonet network device
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Authors: Sakari Ailus <[email protected]>
 *          Rémi Denis-Courmont
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/kernel.h>
#include <linux/net.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/phonet.h>
#include <linux/proc_fs.h>
#include <linux/if_arp.h>
#include <net/sock.h>
#include <net/netns/generic.h>
#include <net/phonet/pn_dev.h>

struct phonet_routes {
    struct mutex        lock;
    struct net_device   *table[64];
};

struct phonet_net {
    struct phonet_device_list pndevs;
    struct phonet_routes routes;
};

static int phonet_net_id __read_mostly;

static struct phonet_net *phonet_pernet(struct net *net)
{
    BUG_ON(!net);

    return net_generic(net, phonet_net_id);
}

struct phonet_device_list *phonet_device_list(struct net *net)
{
    struct phonet_net *pnn = phonet_pernet(net);
    return &pnn->pndevs;
}

/* Allocate new Phonet device. */
static struct phonet_device *__phonet_device_alloc(struct net_device *dev)
{
    struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
    struct phonet_device *pnd = kmalloc(sizeof(*pnd), GFP_ATOMIC);
    if (pnd == NULL)
        return NULL;
    pnd->netdev = dev;
    bitmap_zero(pnd->addrs, 64);

    BUG_ON(!mutex_is_locked(&pndevs->lock));
    list_add_rcu(&pnd->list, &pndevs->list);
    return pnd;
}

static struct phonet_device *__phonet_get(struct net_device *dev)
{
    struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
    struct phonet_device *pnd;

    BUG_ON(!mutex_is_locked(&pndevs->lock));
    list_for_each_entry(pnd, &pndevs->list, list) {
        if (pnd->netdev == dev)
            return pnd;
    }
    return NULL;
}

static struct phonet_device *__phonet_get_rcu(struct net_device *dev)
{
    struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
    struct phonet_device *pnd;

    list_for_each_entry_rcu(pnd, &pndevs->list, list) {
        if (pnd->netdev == dev)
            return pnd;
    }
    return NULL;
}

static void phonet_device_destroy(struct net_device *dev)
{
    struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
    struct phonet_device *pnd;

    ASSERT_RTNL();

    mutex_lock(&pndevs->lock);
    pnd = __phonet_get(dev);
    if (pnd)
        list_del_rcu(&pnd->list);
    mutex_unlock(&pndevs->lock);

    if (pnd) {
        u8 addr;

        for_each_set_bit(addr, pnd->addrs, 64)
            phonet_address_notify(RTM_DELADDR, dev, addr);
        kfree(pnd);
    }
}

struct net_device *phonet_device_get(struct net *net)
{
    struct phonet_device_list *pndevs = phonet_device_list(net);
    struct phonet_device *pnd;
    struct net_device *dev = NULL;

    rcu_read_lock();
    list_for_each_entry_rcu(pnd, &pndevs->list, list) {
        dev = pnd->netdev;
        BUG_ON(!dev);

        if ((dev->reg_state == NETREG_REGISTERED) &&
            ((pnd->netdev->flags & IFF_UP)) == IFF_UP)
            break;
        dev = NULL;
    }
    if (dev)
        dev_hold(dev);
    rcu_read_unlock();
    return dev;
}

int phonet_address_add(struct net_device *dev, u8 addr)
{
    struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
    struct phonet_device *pnd;
    int err = 0;

    mutex_lock(&pndevs->lock);
    /* Find or create Phonet-specific device data */
    pnd = __phonet_get(dev);
    if (pnd == NULL)
        pnd = __phonet_device_alloc(dev);
    if (unlikely(pnd == NULL))
        err = -ENOMEM;
    else if (test_and_set_bit(addr >> 2, pnd->addrs))
        err = -EEXIST;
    mutex_unlock(&pndevs->lock);
    return err;
}

int phonet_address_del(struct net_device *dev, u8 addr)
{
    struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
    struct phonet_device *pnd;
    int err = 0;

    mutex_lock(&pndevs->lock);
    pnd = __phonet_get(dev);
    if (!pnd || !test_and_clear_bit(addr >> 2, pnd->addrs)) {
        err = -EADDRNOTAVAIL;
        pnd = NULL;
    } else if (bitmap_empty(pnd->addrs, 64))
        list_del_rcu(&pnd->list);
    else
        pnd = NULL;
    mutex_unlock(&pndevs->lock);

    if (pnd)
        kfree_rcu(pnd, rcu);

    return err;
}

/* Gets a source address toward a destination, through a interface. */
u8 phonet_address_get(struct net_device *dev, u8 daddr)
{
    struct phonet_device *pnd;
    u8 saddr;

    rcu_read_lock();
    pnd = __phonet_get_rcu(dev);
    if (pnd) {
        BUG_ON(bitmap_empty(pnd->addrs, 64));

        /* Use same source address as destination, if possible */
        if (test_bit(daddr >> 2, pnd->addrs))
            saddr = daddr;
        else
            saddr = find_first_bit(pnd->addrs, 64) << 2;
    } else
        saddr = PN_NO_ADDR;
    rcu_read_unlock();

    if (saddr == PN_NO_ADDR) {
        /* Fallback to another device */
        struct net_device *def_dev;

        def_dev = phonet_device_get(dev_net(dev));
        if (def_dev) {
            if (def_dev != dev)
                saddr = phonet_address_get(def_dev, daddr);
            dev_put(def_dev);
        }
    }
    return saddr;
}

int phonet_address_lookup(struct net *net, u8 addr)
{
    struct phonet_device_list *pndevs = phonet_device_list(net);
    struct phonet_device *pnd;
    int err = -EADDRNOTAVAIL;

    rcu_read_lock();
    list_for_each_entry_rcu(pnd, &pndevs->list, list) {
        /* Don't allow unregistering devices! */
        if ((pnd->netdev->reg_state != NETREG_REGISTERED) ||
                ((pnd->netdev->flags & IFF_UP)) != IFF_UP)
            continue;

        if (test_bit(addr >> 2, pnd->addrs)) {
            err = 0;
            goto found;
        }
    }
found:
    rcu_read_unlock();
    return err;
}

/* automatically configure a Phonet device, if supported */
static int phonet_device_autoconf(struct net_device *dev)
{
    struct if_phonet_req req;
    int ret;

    if (!dev->netdev_ops->ndo_do_ioctl)
        return -EOPNOTSUPP;

    ret = dev->netdev_ops->ndo_do_ioctl(dev, (struct ifreq *)&req,
                        SIOCPNGAUTOCONF);
    if (ret < 0)
        return ret;

    ASSERT_RTNL();
    ret = phonet_address_add(dev, req.ifr_phonet_autoconf.device);
    if (ret)
        return ret;
    phonet_address_notify(RTM_NEWADDR, dev,
                req.ifr_phonet_autoconf.device);
    return 0;
}

static void phonet_route_autodel(struct net_device *dev)
{
    struct phonet_net *pnn = phonet_pernet(dev_net(dev));
    unsigned int i;
    DECLARE_BITMAP(deleted, 64);

    /* Remove left-over Phonet routes */
    bitmap_zero(deleted, 64);
    mutex_lock(&pnn->routes.lock);
    for (i = 0; i < 64; i++)
        if (dev == pnn->routes.table[i]) {
            RCU_INIT_POINTER(pnn->routes.table[i], NULL);
            set_bit(i, deleted);
        }
    mutex_unlock(&pnn->routes.lock);

    if (bitmap_empty(deleted, 64))
        return; /* short-circuit RCU */
    synchronize_rcu();
    for_each_set_bit(i, deleted, 64) {
        rtm_phonet_notify(RTM_DELROUTE, dev, i);
        dev_put(dev);
    }
}

/* notify Phonet of device events */
static int phonet_device_notify(struct notifier_block *me, unsigned long what,
                void *arg)
{
    struct net_device *dev = arg;

    switch (what) {
    case NETDEV_REGISTER:
        if (dev->type == ARPHRD_PHONET)
            phonet_device_autoconf(dev);
        break;
    case NETDEV_UNREGISTER:
        phonet_device_destroy(dev);
        phonet_route_autodel(dev);
        break;
    }
    return 0;

}

static struct notifier_block phonet_device_notifier = {
    .notifier_call = phonet_device_notify,
    .priority = 0,
};

/* Per-namespace Phonet devices handling */
static int __net_init phonet_init_net(struct net *net)
{
    struct phonet_net *pnn = phonet_pernet(net);

    if (!proc_net_fops_create(net, "phonet", 0, &pn_sock_seq_fops))
        return -ENOMEM;

    INIT_LIST_HEAD(&pnn->pndevs.list);
    mutex_init(&pnn->pndevs.lock);
    mutex_init(&pnn->routes.lock);
    return 0;
}

static void __net_exit phonet_exit_net(struct net *net)
{
    proc_net_remove(net, "phonet");
}

static struct pernet_operations phonet_net_ops = {
    .init = phonet_init_net,
    .exit = phonet_exit_net,
    .id   = &phonet_net_id,
    .size = sizeof(struct phonet_net),
};

/* Initialize Phonet devices list */
int __init phonet_device_init(void)
{
    int err = register_pernet_subsys(&phonet_net_ops);
    if (err)
        return err;

    proc_net_fops_create(&init_net, "pnresource", 0, &pn_res_seq_fops);
    register_netdevice_notifier(&phonet_device_notifier);
    err = phonet_netlink_register();
    if (err)
        phonet_device_exit();
    return err;
}

void phonet_device_exit(void)
{
    rtnl_unregister_all(PF_PHONET);
    unregister_netdevice_notifier(&phonet_device_notifier);
    unregister_pernet_subsys(&phonet_net_ops);
    proc_net_remove(&init_net, "pnresource");
}

int phonet_route_add(struct net_device *dev, u8 daddr)
{
    struct phonet_net *pnn = phonet_pernet(dev_net(dev));
    struct phonet_routes *routes = &pnn->routes;
    int err = -EEXIST;

    daddr = daddr >> 2;
    mutex_lock(&routes->lock);
    if (routes->table[daddr] == NULL) {
        rcu_assign_pointer(routes->table[daddr], dev);
        dev_hold(dev);
        err = 0;
    }
    mutex_unlock(&routes->lock);
    return err;
}

int phonet_route_del(struct net_device *dev, u8 daddr)
{
    struct phonet_net *pnn = phonet_pernet(dev_net(dev));
    struct phonet_routes *routes = &pnn->routes;

    daddr = daddr >> 2;
    mutex_lock(&routes->lock);
    if (dev == routes->table[daddr])
        RCU_INIT_POINTER(routes->table[daddr], NULL);
    else
        dev = NULL;
    mutex_unlock(&routes->lock);

    if (!dev)
        return -ENOENT;
    synchronize_rcu();
    dev_put(dev);
    return 0;
}

struct net_device *phonet_route_get_rcu(struct net *net, u8 daddr)
{
    struct phonet_net *pnn = phonet_pernet(net);
    struct phonet_routes *routes = &pnn->routes;
    struct net_device *dev;

    daddr >>= 2;
    dev = rcu_dereference(routes->table[daddr]);
    return dev;
}

struct net_device *phonet_route_output(struct net *net, u8 daddr)
{
    struct phonet_net *pnn = phonet_pernet(net);
    struct phonet_routes *routes = &pnn->routes;
    struct net_device *dev;

    daddr >>= 2;
    rcu_read_lock();
    dev = rcu_dereference(routes->table[daddr]);
    if (dev)
        dev_hold(dev);
    rcu_read_unlock();

    if (!dev)
        dev = phonet_device_get(net); /* Default route */
    return dev;
}