drivers/net/nlmon.c

   1 #include <linux/module.h>
   2 #include <linux/kernel.h>
   3 #include <linux/netdevice.h>
   4 #include <linux/netlink.h>
   5 #include <net/net_namespace.h>
   6 #include <linux/if_arp.h>
   7 #include <net/rtnetlink.h>
   8
   9 static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
  10 {
  11         int len = skb->len;
  12         struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
  13
  14         u64_stats_update_begin(&stats->syncp);
  15         stats->bytes += len;
  16         stats->packets++;
  17         u64_stats_update_end(&stats->syncp);
  18
  19         dev_kfree_skb(skb);
  20
  21         return NETDEV_TX_OK;
  22 }
  23
  24 static int nlmon_dev_init(struct net_device *dev)
  25 {
  26         dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
  27         return dev->lstats == NULL ? -ENOMEM : 0;
  28 }
  29
  30 static void nlmon_dev_uninit(struct net_device *dev)
  31 {
  32         free_percpu(dev->lstats);
  33 }
  34
  35 struct nlmon {
  36         struct netlink_tap nt;
  37 };
  38
  39 static int nlmon_open(struct net_device *dev)
  40 {
  41         struct nlmon *nlmon = netdev_priv(dev);
  42
  43         nlmon->nt.dev = dev;
  44         nlmon->nt.module = THIS_MODULE;
  45         return netlink_add_tap(&nlmon->nt);
  46 }
  47
  48 static int nlmon_close(struct net_device *dev)
  49 {
  50         struct nlmon *nlmon = netdev_priv(dev);
  51
  52         return netlink_remove_tap(&nlmon->nt);
  53 }
  54
  55 static void
  56 nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
  57 {
  58         int i;
  59         u64 bytes = 0, packets = 0;
  60
  61         for_each_possible_cpu(i) {
  62                 const struct pcpu_lstats *nl_stats;
  63                 u64 tbytes, tpackets;
  64                 unsigned int start;
  65
  66                 nl_stats = per_cpu_ptr(dev->lstats, i);
  67
  68                 do {
  69                         start = u64_stats_fetch_begin_irq(&nl_stats->syncp);
  70                         tbytes = nl_stats->bytes;
  71                         tpackets = nl_stats->packets;
  72                 } while (u64_stats_fetch_retry_irq(&nl_stats->syncp, start));
  73
  74                 packets += tpackets;
  75                 bytes += tbytes;
  76         }
  77
  78         stats->rx_packets = packets;
  79         stats->tx_packets = 0;
  80
  81         stats->rx_bytes = bytes;
  82         stats->tx_bytes = 0;
  83 }
  84
  85 static u32 always_on(struct net_device *dev)
  86 {
  87         return 1;
  88 }
  89
  90 static const struct ethtool_ops nlmon_ethtool_ops = {
  91         .get_link = always_on,
  92 };
  93
  94 static const struct net_device_ops nlmon_ops = {
  95         .ndo_init = nlmon_dev_init,
  96         .ndo_uninit = nlmon_dev_uninit,
  97         .ndo_open = nlmon_open,
  98         .ndo_stop = nlmon_close,
  99         .ndo_start_xmit = nlmon_xmit,
 100         .ndo_get_stats64 = nlmon_get_stats64,
 101 };
 102
 103 static void nlmon_setup(struct net_device *dev)
 104 {
 105         dev->type = ARPHRD_NETLINK;
 106         dev->priv_flags |= IFF_NO_QUEUE;
 107
 108         dev->netdev_ops = &nlmon_ops;
 109         dev->ethtool_ops = &nlmon_ethtool_ops;
 110         dev->needs_free_netdev = true;
 111
 112         dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
 113                         NETIF_F_HIGHDMA | NETIF_F_LLTX;
 114         dev->flags = IFF_NOARP;
 115
 116         /* That's rather a softlimit here, which, of course,
 117          * can be altered. Not a real MTU, but what is to be
 118          * expected in most cases.
 119          */
 120         dev->mtu = NLMSG_GOODSIZE;
 121         dev->min_mtu = sizeof(struct nlmsghdr);
 122 }
 123
 124 static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[],
 125                           struct netlink_ext_ack *extack)
 126 {
 127         if (tb[IFLA_ADDRESS])
 128                 return -EINVAL;
 129         return 0;
 130 }
 131
 132 static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
 133         .kind                   = "nlmon",
 134         .priv_size              = sizeof(struct nlmon),
 135         .setup                  = nlmon_setup,
 136         .validate               = nlmon_validate,
 137 };
 138
 139 static __init int nlmon_register(void)
 140 {
 141         return rtnl_link_register(&nlmon_link_ops);
 142 }
 143
 144 static __exit void nlmon_unregister(void)
 145 {
 146         rtnl_link_unregister(&nlmon_link_ops);
 147 }
 148
 149 module_init(nlmon_register);
 150 module_exit(nlmon_unregister);
 151
 152 MODULE_LICENSE("GPL v2");
 153 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
 154 MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
 155 MODULE_DESCRIPTION("Netlink monitoring device");
 156 MODULE_ALIAS_RTNL_LINK("nlmon");