l2tp_eth.c

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/*
 * L2TPv3 ethernet pseudowire driver
 *
 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
 *
 *  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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/hash.h>
#include <linux/l2tp.h>
#include <linux/in.h>
#include <linux/etherdevice.h>
#include <linux/spinlock.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/tcp_states.h>
#include <net/protocol.h>
#include <net/xfrm.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>

#include "l2tp_core.h"

/* Default device name. May be overridden by name specified by user */
#define L2TP_ETH_DEV_NAME   "l2tpeth%d"

/* via netdev_priv() */
struct l2tp_eth {
    struct net_device   *dev;
    struct sock     *tunnel_sock;
    struct l2tp_session *session;
    struct list_head    list;
    atomic_long_t       tx_bytes;
    atomic_long_t       tx_packets;
    atomic_long_t       tx_dropped;
    atomic_long_t       rx_bytes;
    atomic_long_t       rx_packets;
    atomic_long_t       rx_errors;
};

/* via l2tp_session_priv() */
struct l2tp_eth_sess {
    struct net_device   *dev;
};

/* per-net private data for this module */
static unsigned int l2tp_eth_net_id;
struct l2tp_eth_net {
    struct list_head l2tp_eth_dev_list;
    spinlock_t l2tp_eth_lock;
};

static inline struct l2tp_eth_net *l2tp_eth_pernet(struct net *net)
{
    return net_generic(net, l2tp_eth_net_id);
}

static struct lock_class_key l2tp_eth_tx_busylock;
static int l2tp_eth_dev_init(struct net_device *dev)
{
    struct l2tp_eth *priv = netdev_priv(dev);

    priv->dev = dev;
    eth_hw_addr_random(dev);
    memset(&dev->broadcast[0], 0xff, 6);
    dev->qdisc_tx_busylock = &l2tp_eth_tx_busylock;
    return 0;
}

static void l2tp_eth_dev_uninit(struct net_device *dev)
{
    struct l2tp_eth *priv = netdev_priv(dev);
    struct l2tp_eth_net *pn = l2tp_eth_pernet(dev_net(dev));

    spin_lock(&pn->l2tp_eth_lock);
    list_del_init(&priv->list);
    spin_unlock(&pn->l2tp_eth_lock);
    dev_put(dev);
}

static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
{
    struct l2tp_eth *priv = netdev_priv(dev);
    struct l2tp_session *session = priv->session;
    unsigned int len = skb->len;
    int ret = l2tp_xmit_skb(session, skb, session->hdr_len);

    if (likely(ret == NET_XMIT_SUCCESS)) {
        atomic_long_add(len, &priv->tx_bytes);
        atomic_long_inc(&priv->tx_packets);
    } else {
        atomic_long_inc(&priv->tx_dropped);
    }
    return NETDEV_TX_OK;
}

static struct rtnl_link_stats64 *l2tp_eth_get_stats64(struct net_device *dev,
                              struct rtnl_link_stats64 *stats)
{
    struct l2tp_eth *priv = netdev_priv(dev);

    stats->tx_bytes   = atomic_long_read(&priv->tx_bytes);
    stats->tx_packets = atomic_long_read(&priv->tx_packets);
    stats->tx_dropped = atomic_long_read(&priv->tx_dropped);
    stats->rx_bytes   = atomic_long_read(&priv->rx_bytes);
    stats->rx_packets = atomic_long_read(&priv->rx_packets);
    stats->rx_errors  = atomic_long_read(&priv->rx_errors);
    return stats;
}


static struct net_device_ops l2tp_eth_netdev_ops = {
    .ndo_init       = l2tp_eth_dev_init,
    .ndo_uninit     = l2tp_eth_dev_uninit,
    .ndo_start_xmit     = l2tp_eth_dev_xmit,
    .ndo_get_stats64    = l2tp_eth_get_stats64,
};

static void l2tp_eth_dev_setup(struct net_device *dev)
{
    ether_setup(dev);
    dev->priv_flags     &= ~IFF_TX_SKB_SHARING;
    dev->features       |= NETIF_F_LLTX;
    dev->netdev_ops     = &l2tp_eth_netdev_ops;
    dev->destructor     = free_netdev;
}

static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
{
    struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
    struct net_device *dev = spriv->dev;
    struct l2tp_eth *priv = netdev_priv(dev);

    if (session->debug & L2TP_MSG_DATA) {
        unsigned int length;

        length = min(32u, skb->len);
        if (!pskb_may_pull(skb, length))
            goto error;

        pr_debug("%s: eth recv\n", session->name);
        print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
    }

    if (!pskb_may_pull(skb, ETH_HLEN))
        goto error;

    secpath_reset(skb);

    /* checksums verified by L2TP */
    skb->ip_summed = CHECKSUM_NONE;

    skb_dst_drop(skb);
    nf_reset(skb);

    if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
        atomic_long_inc(&priv->rx_packets);
        atomic_long_add(data_len, &priv->rx_bytes);
    } else {
        atomic_long_inc(&priv->rx_errors);
    }
    return;

error:
    atomic_long_inc(&priv->rx_errors);
    kfree_skb(skb);
}

static void l2tp_eth_delete(struct l2tp_session *session)
{
    struct l2tp_eth_sess *spriv;
    struct net_device *dev;

    if (session) {
        spriv = l2tp_session_priv(session);
        dev = spriv->dev;
        if (dev) {
            unregister_netdev(dev);
            spriv->dev = NULL;
            module_put(THIS_MODULE);
        }
    }
}

#if defined(CONFIG_L2TP_DEBUGFS) || defined(CONFIG_L2TP_DEBUGFS_MODULE)
static void l2tp_eth_show(struct seq_file *m, void *arg)
{
    struct l2tp_session *session = arg;
    struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
    struct net_device *dev = spriv->dev;

    seq_printf(m, "   interface %s\n", dev->name);
}
#endif

static int l2tp_eth_create(struct net *net, u32 tunnel_id, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
{
    struct net_device *dev;
    char name[IFNAMSIZ];
    struct l2tp_tunnel *tunnel;
    struct l2tp_session *session;
    struct l2tp_eth *priv;
    struct l2tp_eth_sess *spriv;
    int rc;
    struct l2tp_eth_net *pn;

    tunnel = l2tp_tunnel_find(net, tunnel_id);
    if (!tunnel) {
        rc = -ENODEV;
        goto out;
    }

    session = l2tp_session_find(net, tunnel, session_id);
    if (session) {
        rc = -EEXIST;
        goto out;
    }

    if (cfg->ifname) {
        dev = dev_get_by_name(net, cfg->ifname);
        if (dev) {
            dev_put(dev);
            rc = -EEXIST;
            goto out;
        }
        strlcpy(name, cfg->ifname, IFNAMSIZ);
    } else
        strcpy(name, L2TP_ETH_DEV_NAME);

    session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
                      peer_session_id, cfg);
    if (!session) {
        rc = -ENOMEM;
        goto out;
    }

    dev = alloc_netdev(sizeof(*priv), name, l2tp_eth_dev_setup);
    if (!dev) {
        rc = -ENOMEM;
        goto out_del_session;
    }

    dev_net_set(dev, net);
    if (session->mtu == 0)
        session->mtu = dev->mtu - session->hdr_len;
    dev->mtu = session->mtu;
    dev->needed_headroom += session->hdr_len;

    priv = netdev_priv(dev);
    priv->dev = dev;
    priv->session = session;
    INIT_LIST_HEAD(&priv->list);

    priv->tunnel_sock = tunnel->sock;
    session->recv_skb = l2tp_eth_dev_recv;
    session->session_close = l2tp_eth_delete;
#if defined(CONFIG_L2TP_DEBUGFS) || defined(CONFIG_L2TP_DEBUGFS_MODULE)
    session->show = l2tp_eth_show;
#endif

    spriv = l2tp_session_priv(session);
    spriv->dev = dev;

    rc = register_netdev(dev);
    if (rc < 0)
        goto out_del_dev;

    __module_get(THIS_MODULE);
    /* Must be done after register_netdev() */
    strlcpy(session->ifname, dev->name, IFNAMSIZ);

    dev_hold(dev);
    pn = l2tp_eth_pernet(dev_net(dev));
    spin_lock(&pn->l2tp_eth_lock);
    list_add(&priv->list, &pn->l2tp_eth_dev_list);
    spin_unlock(&pn->l2tp_eth_lock);

    return 0;

out_del_dev:
    free_netdev(dev);
    spriv->dev = NULL;
out_del_session:
    l2tp_session_delete(session);
out:
    return rc;
}

static __net_init int l2tp_eth_init_net(struct net *net)
{
    struct l2tp_eth_net *pn = net_generic(net, l2tp_eth_net_id);

    INIT_LIST_HEAD(&pn->l2tp_eth_dev_list);
    spin_lock_init(&pn->l2tp_eth_lock);

    return 0;
}

static struct pernet_operations l2tp_eth_net_ops = {
    .init = l2tp_eth_init_net,
    .id   = &l2tp_eth_net_id,
    .size = sizeof(struct l2tp_eth_net),
};


static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
    .session_create = l2tp_eth_create,
    .session_delete = l2tp_session_delete,
};


static int __init l2tp_eth_init(void)
{
    int err = 0;

    err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
    if (err)
        goto out;

    err = register_pernet_device(&l2tp_eth_net_ops);
    if (err)
        goto out_unreg;

    pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");

    return 0;

out_unreg:
    l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
out:
    return err;
}

static void __exit l2tp_eth_exit(void)
{
    unregister_pernet_device(&l2tp_eth_net_ops);
    l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
}

module_init(l2tp_eth_init);
module_exit(l2tp_eth_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("James Chapman <[email protected]>");
MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
MODULE_VERSION("1.0");