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_is_valid_mtu(int new_mtu)
  31 {
  32         /* Note that in netlink we do not really have an upper limit. On
  33          * default, we use NLMSG_GOODSIZE. Here at least we should make
  34          * sure that it's at least the header size.
  35          */
  36         return new_mtu >= (int) sizeof(struct nlmsghdr);
  37 }
  38
  39 static int nlmon_change_mtu(struct net_device *dev, int new_mtu)
  40 {
  41         if (!nlmon_is_valid_mtu(new_mtu))
  42                 return -EINVAL;
  43
  44         dev->mtu = new_mtu;
  45         return 0;
  46 }
  47
  48 static int nlmon_dev_init(struct net_device *dev)
  49 {
  50         dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
  51         return dev->lstats == NULL ? -ENOMEM : 0;
  52 }
  53
  54 static void nlmon_dev_uninit(struct net_device *dev)
  55 {
  56         free_percpu(dev->lstats);
  57 }
  58
  59 struct nlmon {
  60         struct netlink_tap nt;
  61 };
  62
  63 static int nlmon_open(struct net_device *dev)
  64 {
  65         struct nlmon *nlmon = netdev_priv(dev);
  66
  67         nlmon->nt.dev = dev;
  68         nlmon->nt.module = THIS_MODULE;
  69         return netlink_add_tap(&nlmon->nt);
  70 }
  71
  72 static int nlmon_close(struct net_device *dev)
  73 {
  74         struct nlmon *nlmon = netdev_priv(dev);
  75
  76         return netlink_remove_tap(&nlmon->nt);
  77 }
  78
  79 static struct rtnl_link_stats64 *
  80 nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
  81 {
  82         int i;
  83         u64 bytes = 0, packets = 0;
  84
  85         for_each_possible_cpu(i) {
  86                 const struct pcpu_lstats *nl_stats;
  87                 u64 tbytes, tpackets;
  88                 unsigned int start;
  89
  90                 nl_stats = per_cpu_ptr(dev->lstats, i);
  91
  92                 do {
  93                         start = u64_stats_fetch_begin_irq(&nl_stats->syncp);
  94                         tbytes = nl_stats->bytes;
  95                         tpackets = nl_stats->packets;
  96                 } while (u64_stats_fetch_retry_irq(&nl_stats->syncp, start));
  97
  98                 packets += tpackets;
  99                 bytes += tbytes;
 100         }
 101
 102         stats->rx_packets = packets;
 103         stats->tx_packets = 0;
 104
 105         stats->rx_bytes = bytes;
 106         stats->tx_bytes = 0;
 107
 108         return stats;
 109 }
 110
 111 static u32 always_on(struct net_device *dev)
 112 {
 113         return 1;
 114 }
 115
 116 static const struct ethtool_ops nlmon_ethtool_ops = {
 117         .get_link = always_on,
 118 };
 119
 120 static const struct net_device_ops nlmon_ops = {
 121         .ndo_init = nlmon_dev_init,
 122         .ndo_uninit = nlmon_dev_uninit,
 123         .ndo_open = nlmon_open,
 124         .ndo_stop = nlmon_close,
 125         .ndo_start_xmit = nlmon_xmit,
 126         .ndo_get_stats64 = nlmon_get_stats64,
 127         .ndo_change_mtu = nlmon_change_mtu,
 128 };
 129
 130 static void nlmon_setup(struct net_device *dev)
 131 {
 132         dev->type = ARPHRD_NETLINK;
 133         dev->priv_flags |= IFF_NO_QUEUE;
 134
 135         dev->netdev_ops = &nlmon_ops;
 136         dev->ethtool_ops = &nlmon_ethtool_ops;
 137         dev->destructor = free_netdev;
 138
 139         dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
 140                         NETIF_F_HIGHDMA | NETIF_F_LLTX;
 141         dev->flags = IFF_NOARP;
 142
 143         /* That's rather a softlimit here, which, of course,
 144          * can be altered. Not a real MTU, but what is to be
 145          * expected in most cases.
 146          */
 147         dev->mtu = NLMSG_GOODSIZE;
 148 }
 149
 150 static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[])
 151 {
 152         if (tb[IFLA_ADDRESS])
 153                 return -EINVAL;
 154         return 0;
 155 }
 156
 157 static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
 158         .kind                   = "nlmon",
 159         .priv_size              = sizeof(struct nlmon),
 160         .setup                  = nlmon_setup,
 161         .validate               = nlmon_validate,
 162 };
 163
 164 static __init int nlmon_register(void)
 165 {
 166         return rtnl_link_register(&nlmon_link_ops);
 167 }
 168
 169 static __exit void nlmon_unregister(void)
 170 {
 171         rtnl_link_unregister(&nlmon_link_ops);
 172 }
 173
 174 module_init(nlmon_register);
 175 module_exit(nlmon_unregister);
 176
 177 MODULE_LICENSE("GPL v2");
 178 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
 179 MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
 180 MODULE_DESCRIPTION("Netlink monitoring device");
 181 MODULE_ALIAS_RTNL_LINK("nlmon");