br_if.c

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/*
 *  Userspace interface
 *  Linux ethernet bridge
 *
 *  Authors:
 *  Lennert Buytenhek       <[email protected]>
 *
 *  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.
 */

#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/netpoll.h>
#include <linux/ethtool.h>
#include <linux/if_arp.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/rtnetlink.h>
#include <linux/if_ether.h>
#include <linux/slab.h>
#include <net/sock.h>

#include "br_private.h"

/*
 * Determine initial path cost based on speed.
 * using recommendations from 802.1d standard
 *
 * Since driver might sleep need to not be holding any locks.
 */
static int port_cost(struct net_device *dev)
{
    struct ethtool_cmd ecmd;

    if (!__ethtool_get_settings(dev, &ecmd)) {
        switch (ethtool_cmd_speed(&ecmd)) {
        case SPEED_10000:
            return 2;
        case SPEED_1000:
            return 4;
        case SPEED_100:
            return 19;
        case SPEED_10:
            return 100;
        }
    }

    /* Old silly heuristics based on name */
    if (!strncmp(dev->name, "lec", 3))
        return 7;

    if (!strncmp(dev->name, "plip", 4))
        return 2500;

    return 100; /* assume old 10Mbps */
}


/* Check for port carrier transistions. */
void br_port_carrier_check(struct net_bridge_port *p)
{
    struct net_device *dev = p->dev;
    struct net_bridge *br = p->br;

    if (netif_running(dev) && netif_carrier_ok(dev))
        p->path_cost = port_cost(dev);

    if (!netif_running(br->dev))
        return;

    spin_lock_bh(&br->lock);
    if (netif_running(dev) && netif_carrier_ok(dev)) {
        if (p->state == BR_STATE_DISABLED)
            br_stp_enable_port(p);
    } else {
        if (p->state != BR_STATE_DISABLED)
            br_stp_disable_port(p);
    }
    spin_unlock_bh(&br->lock);
}

static void release_nbp(struct kobject *kobj)
{
    struct net_bridge_port *p
        = container_of(kobj, struct net_bridge_port, kobj);
    kfree(p);
}

static struct kobj_type brport_ktype = {
#ifdef CONFIG_SYSFS
    .sysfs_ops = &brport_sysfs_ops,
#endif
    .release = release_nbp,
};

static void destroy_nbp(struct net_bridge_port *p)
{
    struct net_device *dev = p->dev;

    p->br = NULL;
    p->dev = NULL;
    dev_put(dev);

    kobject_put(&p->kobj);
}

static void destroy_nbp_rcu(struct rcu_head *head)
{
    struct net_bridge_port *p =
            container_of(head, struct net_bridge_port, rcu);
    destroy_nbp(p);
}

/* Delete port(interface) from bridge is done in two steps.
 * via RCU. First step, marks device as down. That deletes
 * all the timers and stops new packets from flowing through.
 *
 * Final cleanup doesn't occur until after all CPU's finished
 * processing packets.
 *
 * Protected from multiple admin operations by RTNL mutex
 */
static void del_nbp(struct net_bridge_port *p)
{
    struct net_bridge *br = p->br;
    struct net_device *dev = p->dev;

    sysfs_remove_link(br->ifobj, p->dev->name);

    dev_set_promiscuity(dev, -1);

    spin_lock_bh(&br->lock);
    br_stp_disable_port(p);
    spin_unlock_bh(&br->lock);

    br_ifinfo_notify(RTM_DELLINK, p);

    br_fdb_delete_by_port(br, p, 1);

    list_del_rcu(&p->list);

    dev->priv_flags &= ~IFF_BRIDGE_PORT;

    netdev_rx_handler_unregister(dev);
    synchronize_net();

    netdev_set_master(dev, NULL);

    br_multicast_del_port(p);

    kobject_uevent(&p->kobj, KOBJ_REMOVE);
    kobject_del(&p->kobj);

    br_netpoll_disable(p);

    call_rcu(&p->rcu, destroy_nbp_rcu);
}

/* Delete bridge device */
void br_dev_delete(struct net_device *dev, struct list_head *head)
{
    struct net_bridge *br = netdev_priv(dev);
    struct net_bridge_port *p, *n;

    list_for_each_entry_safe(p, n, &br->port_list, list) {
        del_nbp(p);
    }

    del_timer_sync(&br->gc_timer);

    br_sysfs_delbr(br->dev);
    unregister_netdevice_queue(br->dev, head);
}

/* find an available port number */
static int find_portno(struct net_bridge *br)
{
    int index;
    struct net_bridge_port *p;
    unsigned long *inuse;

    inuse = kcalloc(BITS_TO_LONGS(BR_MAX_PORTS), sizeof(unsigned long),
            GFP_KERNEL);
    if (!inuse)
        return -ENOMEM;

    set_bit(0, inuse);  /* zero is reserved */
    list_for_each_entry(p, &br->port_list, list) {
        set_bit(p->port_no, inuse);
    }
    index = find_first_zero_bit(inuse, BR_MAX_PORTS);
    kfree(inuse);

    return (index >= BR_MAX_PORTS) ? -EXFULL : index;
}

/* called with RTNL but without bridge lock */
static struct net_bridge_port *new_nbp(struct net_bridge *br,
                       struct net_device *dev)
{
    int index;
    struct net_bridge_port *p;

    index = find_portno(br);
    if (index < 0)
        return ERR_PTR(index);

    p = kzalloc(sizeof(*p), GFP_KERNEL);
    if (p == NULL)
        return ERR_PTR(-ENOMEM);

    p->br = br;
    dev_hold(dev);
    p->dev = dev;
    p->path_cost = port_cost(dev);
    p->priority = 0x8000 >> BR_PORT_BITS;
    p->port_no = index;
    p->flags = 0;
    br_init_port(p);
    p->state = BR_STATE_DISABLED;
    br_stp_port_timer_init(p);
    br_multicast_add_port(p);

    return p;
}

int br_add_bridge(struct net *net, const char *name)
{
    struct net_device *dev;
    int res;

    dev = alloc_netdev(sizeof(struct net_bridge), name,
               br_dev_setup);

    if (!dev)
        return -ENOMEM;

    dev_net_set(dev, net);
    dev->rtnl_link_ops = &br_link_ops;

    res = register_netdev(dev);
    if (res)
        free_netdev(dev);
    return res;
}

int br_del_bridge(struct net *net, const char *name)
{
    struct net_device *dev;
    int ret = 0;

    rtnl_lock();
    dev = __dev_get_by_name(net, name);
    if (dev == NULL)
        ret =  -ENXIO;  /* Could not find device */

    else if (!(dev->priv_flags & IFF_EBRIDGE)) {
        /* Attempt to delete non bridge device! */
        ret = -EPERM;
    }

    else if (dev->flags & IFF_UP) {
        /* Not shutdown yet. */
        ret = -EBUSY;
    }

    else
        br_dev_delete(dev, NULL);

    rtnl_unlock();
    return ret;
}

/* MTU of the bridge pseudo-device: ETH_DATA_LEN or the minimum of the ports */
int br_min_mtu(const struct net_bridge *br)
{
    const struct net_bridge_port *p;
    int mtu = 0;

    ASSERT_RTNL();

    if (list_empty(&br->port_list))
        mtu = ETH_DATA_LEN;
    else {
        list_for_each_entry(p, &br->port_list, list) {
            if (!mtu  || p->dev->mtu < mtu)
                mtu = p->dev->mtu;
        }
    }
    return mtu;
}

/*
 * Recomputes features using slave's features
 */
netdev_features_t br_features_recompute(struct net_bridge *br,
    netdev_features_t features)
{
    struct net_bridge_port *p;
    netdev_features_t mask;

    if (list_empty(&br->port_list))
        return features;

    mask = features;
    features &= ~NETIF_F_ONE_FOR_ALL;

    list_for_each_entry(p, &br->port_list, list) {
        features = netdev_increment_features(features,
                             p->dev->features, mask);
    }

    return features;
}

/* called with RTNL */
int br_add_if(struct net_bridge *br, struct net_device *dev)
{
    struct net_bridge_port *p;
    int err = 0;
    bool changed_addr;

    /* Don't allow bridging non-ethernet like devices */
    if ((dev->flags & IFF_LOOPBACK) ||
        dev->type != ARPHRD_ETHER || dev->addr_len != ETH_ALEN ||
        !is_valid_ether_addr(dev->dev_addr))
        return -EINVAL;

    /* No bridging of bridges */
    if (dev->netdev_ops->ndo_start_xmit == br_dev_xmit)
        return -ELOOP;

    /* Device is already being bridged */
    if (br_port_exists(dev))
        return -EBUSY;

    /* No bridging devices that dislike that (e.g. wireless) */
    if (dev->priv_flags & IFF_DONT_BRIDGE)
        return -EOPNOTSUPP;

    p = new_nbp(br, dev);
    if (IS_ERR(p))
        return PTR_ERR(p);

    call_netdevice_notifiers(NETDEV_JOIN, dev);

    err = dev_set_promiscuity(dev, 1);
    if (err)
        goto put_back;

    err = kobject_init_and_add(&p->kobj, &brport_ktype, &(dev->dev.kobj),
                   SYSFS_BRIDGE_PORT_ATTR);
    if (err)
        goto err1;

    err = br_sysfs_addif(p);
    if (err)
        goto err2;

    if (br_netpoll_info(br) && ((err = br_netpoll_enable(p, GFP_KERNEL))))
        goto err3;

    err = netdev_set_master(dev, br->dev);
    if (err)
        goto err3;

    err = netdev_rx_handler_register(dev, br_handle_frame, p);
    if (err)
        goto err4;

    dev->priv_flags |= IFF_BRIDGE_PORT;

    dev_disable_lro(dev);

    list_add_rcu(&p->list, &br->port_list);

    netdev_update_features(br->dev);

    spin_lock_bh(&br->lock);
    changed_addr = br_stp_recalculate_bridge_id(br);

    if ((dev->flags & IFF_UP) && netif_carrier_ok(dev) &&
        (br->dev->flags & IFF_UP))
        br_stp_enable_port(p);
    spin_unlock_bh(&br->lock);

    br_ifinfo_notify(RTM_NEWLINK, p);

    if (changed_addr)
        call_netdevice_notifiers(NETDEV_CHANGEADDR, br->dev);

    dev_set_mtu(br->dev, br_min_mtu(br));

    if (br_fdb_insert(br, p, dev->dev_addr))
        netdev_err(dev, "failed insert local address bridge forwarding table\n");

    kobject_uevent(&p->kobj, KOBJ_ADD);

    return 0;

err4:
    netdev_set_master(dev, NULL);
err3:
    sysfs_remove_link(br->ifobj, p->dev->name);
err2:
    kobject_put(&p->kobj);
    p = NULL; /* kobject_put frees */
err1:
    dev_set_promiscuity(dev, -1);
put_back:
    dev_put(dev);
    kfree(p);
    return err;
}

/* called with RTNL */
int br_del_if(struct net_bridge *br, struct net_device *dev)
{
    struct net_bridge_port *p;
    bool changed_addr;

    p = br_port_get_rtnl(dev);
    if (!p || p->br != br)
        return -EINVAL;

    /* Since more than one interface can be attached to a bridge,
     * there still maybe an alternate path for netconsole to use;
     * therefore there is no reason for a NETDEV_RELEASE event.
     */
    del_nbp(p);

    spin_lock_bh(&br->lock);
    changed_addr = br_stp_recalculate_bridge_id(br);
    spin_unlock_bh(&br->lock);

    if (changed_addr)
        call_netdevice_notifiers(NETDEV_CHANGEADDR, br->dev);

    netdev_update_features(br->dev);

    return 0;
}

void __net_exit br_net_exit(struct net *net)
{
    struct net_device *dev;
    LIST_HEAD(list);

    rtnl_lock();
    for_each_netdev(net, dev)
        if (dev->priv_flags & IFF_EBRIDGE)
            br_dev_delete(dev, &list);

    unregister_netdevice_many(&list);
    rtnl_unlock();

}