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