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 void
  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
  91 static u32 always_on(struct net_device *dev)
  92 {
  93         return 1;
  94 }
  95
  96 static const struct ethtool_ops nlmon_ethtool_ops = {
  97         .get_link = always_on,
  98 };
  99
 100 static const struct net_device_ops nlmon_ops = {
 101         .ndo_init = nlmon_dev_init,
 102         .ndo_uninit = nlmon_dev_uninit,
 103         .ndo_open = nlmon_open,
 104         .ndo_stop = nlmon_close,
 105         .ndo_start_xmit = nlmon_xmit,
 106         .ndo_get_stats64 = nlmon_get_stats64,
 107 };
 108
 109 static void nlmon_setup(struct net_device *dev)
 110 {
 111         dev->type = ARPHRD_NETLINK;
 112         dev->priv_flags |= IFF_NO_QUEUE;
 113
 114         dev->netdev_ops = &nlmon_ops;
 115         dev->ethtool_ops = &nlmon_ethtool_ops;
 116         dev->needs_free_netdev = true;
 117
 118         dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
 119                         NETIF_F_HIGHDMA | NETIF_F_LLTX;
 120         dev->flags = IFF_NOARP;
 121
 122         /* That's rather a softlimit here, which, of course,
 123          * can be altered. Not a real MTU, but what is to be
 124          * expected in most cases.
 125          */
 126         dev->mtu = NLMSG_GOODSIZE;
 127         dev->min_mtu = sizeof(struct nlmsghdr);
 128 }
 129
 130 static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[],
 131                           struct netlink_ext_ack *extack)
 132 {
 133         if (tb[IFLA_ADDRESS])
 134                 return -EINVAL;
 135         return 0;
 136 }
 137
 138 static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
 139         .kind                   = "nlmon",
 140         .priv_size              = sizeof(struct nlmon),
 141         .setup                  = nlmon_setup,
 142         .validate               = nlmon_validate,
 143 };
 144
 145 static __init int nlmon_register(void)
 146 {
 147         return rtnl_link_register(&nlmon_link_ops);
 148 }
 149
 150 static __exit void nlmon_unregister(void)
 151 {
 152         rtnl_link_unregister(&nlmon_link_ops);
 153 }
 154
 155 module_init(nlmon_register);
 156 module_exit(nlmon_unregister);
 157
 158 MODULE_LICENSE("GPL v2");
 159 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
 160 MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
 161 MODULE_DESCRIPTION("Netlink monitoring device");
 162 MODULE_ALIAS_RTNL_LINK("nlmon");