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
  10 static 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
  19 static 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
  25 static void nlmon_dev_uninit(struct net_device *dev)
  26 {
  27         free_percpu(dev->lstats);
  28 }
  29
  30 struct nlmon {
  31         struct netlink_tap nt;
  32 };
  33
  34 static 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
  43 static 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
  50 static void
  51 nlmon_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
  64 static u32 always_on(struct net_device *dev)
  65 {
  66         return 1;
  67 }
  68
  69 static const struct ethtool_ops nlmon_ethtool_ops = {
  70         .get_link = always_on,
  71 };
  72
  73 static 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
  82 static 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
 103 static 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
 111 static 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
 118 static __init int nlmon_register(void)
 119 {
 120         return rtnl_link_register(&nlmon_link_ops);
 121 }
 122
 123 static __exit void nlmon_unregister(void)
 124 {
 125         rtnl_link_unregister(&nlmon_link_ops);
 126 }
 127
 128 module_init(nlmon_register);
 129 module_exit(nlmon_unregister);
 130
 131 MODULE_LICENSE("GPL v2");
 132 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
 133 MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
 134 MODULE_DESCRIPTION("Netlink monitoring device");
 135 MODULE_ALIAS_RTNL_LINK("nlmon");