LXR linux/drivers/net/nlmon.c

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