LXR linux/drivers/net/nlmon.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2#include <linux/ethtool.h>
   3#include <linux/module.h>
   4#include <linux/kernel.h>
   5#include <linux/netdevice.h>
   6#include <linux/netlink.h>
   7#include <net/net_namespace.h>
   8#include <linux/if_arp.h>
   9#include <net/rtnetlink.h>
  10
  11static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
  12{
  13        dev_lstats_add(dev, skb->len);
  14
  15        dev_kfree_skb(skb);
  16
  17        return NETDEV_TX_OK;
  18}
  19
  20static int nlmon_dev_init(struct net_device *dev)
  21{
  22        dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
  23        return dev->lstats == NULL ? -ENOMEM : 0;
  24}
  25
  26static void nlmon_dev_uninit(struct net_device *dev)
  27{
  28        free_percpu(dev->lstats);
  29}
  30
  31struct nlmon {
  32        struct netlink_tap nt;
  33};
  34
  35static int nlmon_open(struct net_device *dev)
  36{
  37        struct nlmon *nlmon = netdev_priv(dev);
  38
  39        nlmon->nt.dev = dev;
  40        nlmon->nt.module = THIS_MODULE;
  41        return netlink_add_tap(&nlmon->nt);
  42}
  43
  44static int nlmon_close(struct net_device *dev)
  45{
  46        struct nlmon *nlmon = netdev_priv(dev);
  47
  48        return netlink_remove_tap(&nlmon->nt);
  49}
  50
  51static void
  52nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
  53{
  54        u64 packets, bytes;
  55
  56        dev_lstats_read(dev, &packets, &bytes);
  57
  58        stats->rx_packets = packets;
  59        stats->tx_packets = 0;
  60
  61        stats->rx_bytes = bytes;
  62        stats->tx_bytes = 0;
  63}
  64
  65static u32 always_on(struct net_device *dev)
  66{
  67        return 1;
  68}
  69
  70static const struct ethtool_ops nlmon_ethtool_ops = {
  71        .get_link = always_on,
  72};
  73
  74static const struct net_device_ops nlmon_ops = {
  75        .ndo_init = nlmon_dev_init,
  76        .ndo_uninit = nlmon_dev_uninit,
  77        .ndo_open = nlmon_open,
  78        .ndo_stop = nlmon_close,
  79        .ndo_start_xmit = nlmon_xmit,
  80        .ndo_get_stats64 = nlmon_get_stats64,
  81};
  82
  83static void nlmon_setup(struct net_device *dev)
  84{
  85        dev->type = ARPHRD_NETLINK;
  86        dev->priv_flags |= IFF_NO_QUEUE;
  87
  88        dev->netdev_ops = &nlmon_ops;
  89        dev->ethtool_ops = &nlmon_ethtool_ops;
  90        dev->needs_free_netdev = true;
  91
  92        dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
  93                        NETIF_F_HIGHDMA | NETIF_F_LLTX;
  94        dev->flags = IFF_NOARP;
  95
  96        /* That's rather a softlimit here, which, of course,
  97         * can be altered. Not a real MTU, but what is to be
  98         * expected in most cases.
  99         */
 100        dev->mtu = NLMSG_GOODSIZE;
 101        dev->min_mtu = sizeof(struct nlmsghdr);
 102}
 103
 104static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[],
 105                          struct netlink_ext_ack *extack)
 106{
 107        if (tb[IFLA_ADDRESS])
 108                return -EINVAL;
 109        return 0;
 110}
 111
 112static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
 113        .kind                   = "nlmon",
 114        .priv_size              = sizeof(struct nlmon),
 115        .setup                  = nlmon_setup,
 116        .validate               = nlmon_validate,
 117};
 118
 119static __init int nlmon_register(void)
 120{
 121        return rtnl_link_register(&nlmon_link_ops);
 122}
 123
 124static __exit void nlmon_unregister(void)
 125{
 126        rtnl_link_unregister(&nlmon_link_ops);
 127}
 128
 129module_init(nlmon_register);
 130module_exit(nlmon_unregister);
 131
 132MODULE_LICENSE("GPL v2");
 133MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
 134MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
 135MODULE_DESCRIPTION("Netlink monitoring device");
 136MODULE_ALIAS_RTNL_LINK("nlmon");
 137