veth.c

Go to the documentation of this file.

/*
 *  drivers/net/veth.c
 *
 *  Copyright (C) 2007 OpenVZ http://openvz.org, SWsoft Inc
 *
 * Author: Pavel Emelianov <[email protected]>
 * Ethtool interface from: Eric W. Biederman <[email protected]>
 *
 */

#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/ethtool.h>
#include <linux/etherdevice.h>
#include <linux/u64_stats_sync.h>

#include <net/dst.h>
#include <net/xfrm.h>
#include <linux/veth.h>
#include <linux/module.h>

#define DRV_NAME    "veth"
#define DRV_VERSION "1.0"

#define MIN_MTU 68      /* Min L3 MTU */
#define MAX_MTU 65535       /* Max L3 MTU (arbitrary) */

struct veth_net_stats {
    u64         rx_packets;
    u64         rx_bytes;
    u64         tx_packets;
    u64         tx_bytes;
    u64         rx_dropped;
    struct u64_stats_sync   syncp;
};

struct veth_priv {
    struct net_device *peer;
    struct veth_net_stats __percpu *stats;
};

/*
 * ethtool interface
 */

static struct {
    const char string[ETH_GSTRING_LEN];
} ethtool_stats_keys[] = {
    { "peer_ifindex" },
};

static int veth_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
{
    cmd->supported      = 0;
    cmd->advertising    = 0;
    ethtool_cmd_speed_set(cmd, SPEED_10000);
    cmd->duplex     = DUPLEX_FULL;
    cmd->port       = PORT_TP;
    cmd->phy_address    = 0;
    cmd->transceiver    = XCVR_INTERNAL;
    cmd->autoneg        = AUTONEG_DISABLE;
    cmd->maxtxpkt       = 0;
    cmd->maxrxpkt       = 0;
    return 0;
}

static void veth_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
{
    strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
    strlcpy(info->version, DRV_VERSION, sizeof(info->version));
}

static void veth_get_strings(struct net_device *dev, u32 stringset, u8 *buf)
{
    switch(stringset) {
    case ETH_SS_STATS:
        memcpy(buf, &ethtool_stats_keys, sizeof(ethtool_stats_keys));
        break;
    }
}

static int veth_get_sset_count(struct net_device *dev, int sset)
{
    switch (sset) {
    case ETH_SS_STATS:
        return ARRAY_SIZE(ethtool_stats_keys);
    default:
        return -EOPNOTSUPP;
    }
}

static void veth_get_ethtool_stats(struct net_device *dev,
        struct ethtool_stats *stats, u64 *data)
{
    struct veth_priv *priv;

    priv = netdev_priv(dev);
    data[0] = priv->peer->ifindex;
}

static const struct ethtool_ops veth_ethtool_ops = {
    .get_settings       = veth_get_settings,
    .get_drvinfo        = veth_get_drvinfo,
    .get_link       = ethtool_op_get_link,
    .get_strings        = veth_get_strings,
    .get_sset_count     = veth_get_sset_count,
    .get_ethtool_stats  = veth_get_ethtool_stats,
};

/*
 * xmit
 */

static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
{
    struct net_device *rcv = NULL;
    struct veth_priv *priv, *rcv_priv;
    struct veth_net_stats *stats, *rcv_stats;
    int length;

    priv = netdev_priv(dev);
    rcv = priv->peer;
    rcv_priv = netdev_priv(rcv);

    stats = this_cpu_ptr(priv->stats);
    rcv_stats = this_cpu_ptr(rcv_priv->stats);

    /* don't change ip_summed == CHECKSUM_PARTIAL, as that
       will cause bad checksum on forwarded packets */
    if (skb->ip_summed == CHECKSUM_NONE &&
        rcv->features & NETIF_F_RXCSUM)
        skb->ip_summed = CHECKSUM_UNNECESSARY;

    length = skb->len;
    if (dev_forward_skb(rcv, skb) != NET_RX_SUCCESS)
        goto rx_drop;

    u64_stats_update_begin(&stats->syncp);
    stats->tx_bytes += length;
    stats->tx_packets++;
    u64_stats_update_end(&stats->syncp);

    u64_stats_update_begin(&rcv_stats->syncp);
    rcv_stats->rx_bytes += length;
    rcv_stats->rx_packets++;
    u64_stats_update_end(&rcv_stats->syncp);

    return NETDEV_TX_OK;

rx_drop:
    u64_stats_update_begin(&rcv_stats->syncp);
    rcv_stats->rx_dropped++;
    u64_stats_update_end(&rcv_stats->syncp);
    return NETDEV_TX_OK;
}

/*
 * general routines
 */

static struct rtnl_link_stats64 *veth_get_stats64(struct net_device *dev,
                          struct rtnl_link_stats64 *tot)
{
    struct veth_priv *priv = netdev_priv(dev);
    int cpu;

    for_each_possible_cpu(cpu) {
        struct veth_net_stats *stats = per_cpu_ptr(priv->stats, cpu);
        u64 rx_packets, rx_bytes, rx_dropped;
        u64 tx_packets, tx_bytes;
        unsigned int start;

        do {
            start = u64_stats_fetch_begin_bh(&stats->syncp);
            rx_packets = stats->rx_packets;
            tx_packets = stats->tx_packets;
            rx_bytes = stats->rx_bytes;
            tx_bytes = stats->tx_bytes;
            rx_dropped = stats->rx_dropped;
        } while (u64_stats_fetch_retry_bh(&stats->syncp, start));
        tot->rx_packets += rx_packets;
        tot->tx_packets += tx_packets;
        tot->rx_bytes   += rx_bytes;
        tot->tx_bytes   += tx_bytes;
        tot->rx_dropped += rx_dropped;
    }

    return tot;
}

static int veth_open(struct net_device *dev)
{
    struct veth_priv *priv;

    priv = netdev_priv(dev);
    if (priv->peer == NULL)
        return -ENOTCONN;

    if (priv->peer->flags & IFF_UP) {
        netif_carrier_on(dev);
        netif_carrier_on(priv->peer);
    }
    return 0;
}

static int veth_close(struct net_device *dev)
{
    struct veth_priv *priv = netdev_priv(dev);

    netif_carrier_off(dev);
    netif_carrier_off(priv->peer);

    return 0;
}

static int is_valid_veth_mtu(int new_mtu)
{
    return new_mtu >= MIN_MTU && new_mtu <= MAX_MTU;
}

static int veth_change_mtu(struct net_device *dev, int new_mtu)
{
    if (!is_valid_veth_mtu(new_mtu))
        return -EINVAL;
    dev->mtu = new_mtu;
    return 0;
}

static int veth_dev_init(struct net_device *dev)
{
    struct veth_net_stats __percpu *stats;
    struct veth_priv *priv;

    stats = alloc_percpu(struct veth_net_stats);
    if (stats == NULL)
        return -ENOMEM;

    priv = netdev_priv(dev);
    priv->stats = stats;
    return 0;
}

static void veth_dev_free(struct net_device *dev)
{
    struct veth_priv *priv;

    priv = netdev_priv(dev);
    free_percpu(priv->stats);
    free_netdev(dev);
}

static const struct net_device_ops veth_netdev_ops = {
    .ndo_init            = veth_dev_init,
    .ndo_open            = veth_open,
    .ndo_stop            = veth_close,
    .ndo_start_xmit      = veth_xmit,
    .ndo_change_mtu      = veth_change_mtu,
    .ndo_get_stats64     = veth_get_stats64,
    .ndo_set_mac_address = eth_mac_addr,
};

static void veth_setup(struct net_device *dev)
{
    ether_setup(dev);

    dev->priv_flags &= ~IFF_TX_SKB_SHARING;

    dev->netdev_ops = &veth_netdev_ops;
    dev->ethtool_ops = &veth_ethtool_ops;
    dev->features |= NETIF_F_LLTX;
    dev->destructor = veth_dev_free;

    dev->hw_features = NETIF_F_HW_CSUM | NETIF_F_SG | NETIF_F_RXCSUM;
}

/*
 * netlink interface
 */

static int veth_validate(struct nlattr *tb[], struct nlattr *data[])
{
    if (tb[IFLA_ADDRESS]) {
        if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
            return -EINVAL;
        if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
            return -EADDRNOTAVAIL;
    }
    if (tb[IFLA_MTU]) {
        if (!is_valid_veth_mtu(nla_get_u32(tb[IFLA_MTU])))
            return -EINVAL;
    }
    return 0;
}

static struct rtnl_link_ops veth_link_ops;

static int veth_newlink(struct net *src_net, struct net_device *dev,
             struct nlattr *tb[], struct nlattr *data[])
{
    int err;
    struct net_device *peer;
    struct veth_priv *priv;
    char ifname[IFNAMSIZ];
    struct nlattr *peer_tb[IFLA_MAX + 1], **tbp;
    struct ifinfomsg *ifmp;
    struct net *net;

    /*
     * create and register peer first
     */
    if (data != NULL && data[VETH_INFO_PEER] != NULL) {
        struct nlattr *nla_peer;

        nla_peer = data[VETH_INFO_PEER];
        ifmp = nla_data(nla_peer);
        err = nla_parse(peer_tb, IFLA_MAX,
                nla_data(nla_peer) + sizeof(struct ifinfomsg),
                nla_len(nla_peer) - sizeof(struct ifinfomsg),
                ifla_policy);
        if (err < 0)
            return err;

        err = veth_validate(peer_tb, NULL);
        if (err < 0)
            return err;

        tbp = peer_tb;
    } else {
        ifmp = NULL;
        tbp = tb;
    }

    if (tbp[IFLA_IFNAME])
        nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
    else
        snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");

    net = rtnl_link_get_net(src_net, tbp);
    if (IS_ERR(net))
        return PTR_ERR(net);

    peer = rtnl_create_link(src_net, net, ifname, &veth_link_ops, tbp);
    if (IS_ERR(peer)) {
        put_net(net);
        return PTR_ERR(peer);
    }

    if (tbp[IFLA_ADDRESS] == NULL)
        eth_hw_addr_random(peer);

    if (ifmp && (dev->ifindex != 0))
        peer->ifindex = ifmp->ifi_index;

    err = register_netdevice(peer);
    put_net(net);
    net = NULL;
    if (err < 0)
        goto err_register_peer;

    netif_carrier_off(peer);

    err = rtnl_configure_link(peer, ifmp);
    if (err < 0)
        goto err_configure_peer;

    /*
     * register dev last
     *
     * note, that since we've registered new device the dev's name
     * should be re-allocated
     */

    if (tb[IFLA_ADDRESS] == NULL)
        eth_hw_addr_random(dev);

    if (tb[IFLA_IFNAME])
        nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
    else
        snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");

    if (strchr(dev->name, '%')) {
        err = dev_alloc_name(dev, dev->name);
        if (err < 0)
            goto err_alloc_name;
    }

    err = register_netdevice(dev);
    if (err < 0)
        goto err_register_dev;

    netif_carrier_off(dev);

    /*
     * tie the deviced together
     */

    priv = netdev_priv(dev);
    priv->peer = peer;

    priv = netdev_priv(peer);
    priv->peer = dev;
    return 0;

err_register_dev:
    /* nothing to do */
err_alloc_name:
err_configure_peer:
    unregister_netdevice(peer);
    return err;

err_register_peer:
    free_netdev(peer);
    return err;
}

static void veth_dellink(struct net_device *dev, struct list_head *head)
{
    struct veth_priv *priv;
    struct net_device *peer;

    priv = netdev_priv(dev);
    peer = priv->peer;

    unregister_netdevice_queue(dev, head);
    unregister_netdevice_queue(peer, head);
}

static const struct nla_policy veth_policy[VETH_INFO_MAX + 1] = {
    [VETH_INFO_PEER]    = { .len = sizeof(struct ifinfomsg) },
};

static struct rtnl_link_ops veth_link_ops = {
    .kind       = DRV_NAME,
    .priv_size  = sizeof(struct veth_priv),
    .setup      = veth_setup,
    .validate   = veth_validate,
    .newlink    = veth_newlink,
    .dellink    = veth_dellink,
    .policy     = veth_policy,
    .maxtype    = VETH_INFO_MAX,
};

/*
 * init/fini
 */

static __init int veth_init(void)
{
    return rtnl_link_register(&veth_link_ops);
}

static __exit void veth_exit(void)
{
    rtnl_link_unregister(&veth_link_ops);
}

module_init(veth_init);
module_exit(veth_exit);

MODULE_DESCRIPTION("Virtual Ethernet Tunnel");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_RTNL_LINK(DRV_NAME);