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 struct pcpu_lstats {
  10         u64 packets;
  11         u64 bytes;
  12         struct u64_stats_sync syncp;
  13 };
  14
  15 static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
  16 {
  17         int len = skb->len;
  18         struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
  19
  20         u64_stats_update_begin(&stats->syncp);
  21         stats->bytes += len;
  22         stats->packets++;
  23         u64_stats_update_end(&stats->syncp);
  24
  25         dev_kfree_skb(skb);
  26
  27         return NETDEV_TX_OK;
  28 }
  29
  30 static int nlmon_dev_init(struct net_device *dev)
  31 {
  32         dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
  33         return dev->lstats == NULL ? -ENOMEM : 0;
  34 }
  35
  36 static void nlmon_dev_uninit(struct net_device *dev)
  37 {
  38         free_percpu(dev->lstats);
  39 }
  40
  41 struct nlmon {
  42         struct netlink_tap nt;
  43 };
  44
  45 static int nlmon_open(struct net_device *dev)
  46 {
  47         struct nlmon *nlmon = netdev_priv(dev);
  48
  49         nlmon->nt.dev = dev;
  50         nlmon->nt.module = THIS_MODULE;
  51         return netlink_add_tap(&nlmon->nt);
  52 }
  53
  54 static int nlmon_close(struct net_device *dev)
  55 {
  56         struct nlmon *nlmon = netdev_priv(dev);
  57
  58         return netlink_remove_tap(&nlmon->nt);
  59 }
  60
  61 static struct rtnl_link_stats64 *
  62 nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
  63 {
  64         int i;
  65         u64 bytes = 0, packets = 0;
  66
  67         for_each_possible_cpu(i) {
  68                 const struct pcpu_lstats *nl_stats;
  69                 u64 tbytes, tpackets;
  70                 unsigned int start;
  71
  72                 nl_stats = per_cpu_ptr(dev->lstats, i);
  73
  74                 do {
  75                         start = u64_stats_fetch_begin_irq(&nl_stats->syncp);
  76                         tbytes = nl_stats->bytes;
  77                         tpackets = nl_stats->packets;
  78                 } while (u64_stats_fetch_retry_irq(&nl_stats->syncp, start));
  79
  80                 packets += tpackets;
  81                 bytes += tbytes;
  82         }
  83
  84         stats->rx_packets = packets;
  85         stats->tx_packets = 0;
  86
  87         stats->rx_bytes = bytes;
  88         stats->tx_bytes = 0;
  89
  90         return stats;
  91 }
  92
  93 static u32 always_on(struct net_device *dev)
  94 {
  95         return 1;
  96 }
  97
  98 static const struct ethtool_ops nlmon_ethtool_ops = {
  99         .get_link = always_on,
 100 };
 101
 102 static const struct net_device_ops nlmon_ops = {
 103         .ndo_init = nlmon_dev_init,
 104         .ndo_uninit = nlmon_dev_uninit,
 105         .ndo_open = nlmon_open,
 106         .ndo_stop = nlmon_close,
 107         .ndo_start_xmit = nlmon_xmit,
 108         .ndo_get_stats64 = nlmon_get_stats64,
 109 };
 110
 111 static void nlmon_setup(struct net_device *dev)
 112 {
 113         dev->type = ARPHRD_NETLINK;
 114         dev->priv_flags |= IFF_NO_QUEUE;
 115
 116         dev->netdev_ops = &nlmon_ops;
 117         dev->ethtool_ops = &nlmon_ethtool_ops;
 118         dev->destructor = free_netdev;
 119
 120         dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
 121                         NETIF_F_HIGHDMA | NETIF_F_LLTX;
 122         dev->flags = IFF_NOARP;
 123
 124         /* That's rather a softlimit here, which, of course,
 125          * can be altered. Not a real MTU, but what is to be
 126          * expected in most cases.
 127          */
 128         dev->mtu = NLMSG_GOODSIZE;
 129         dev->min_mtu = sizeof(struct nlmsghdr);
 130 }
 131
 132 static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[])
 133 {
 134         if (tb[IFLA_ADDRESS])
 135                 return -EINVAL;
 136         return 0;
 137 }
 138
 139 static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
 140         .kind                   = "nlmon",
 141         .priv_size              = sizeof(struct nlmon),
 142         .setup                  = nlmon_setup,
 143         .validate               = nlmon_validate,
 144 };
 145
 146 static __init int nlmon_register(void)
 147 {
 148         return rtnl_link_register(&nlmon_link_ops);
 149 }
 150
 151 static __exit void nlmon_unregister(void)
 152 {
 153         rtnl_link_unregister(&nlmon_link_ops);
 154 }
 155
 156 module_init(nlmon_register);
 157 module_exit(nlmon_unregister);
 158
 159 MODULE_LICENSE("GPL v2");
 160 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
 161 MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
 162 MODULE_DESCRIPTION("Netlink monitoring device");
 163 MODULE_ALIAS_RTNL_LINK("nlmon");