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 = alloc_percpu(struct pcpu_lstats);
  51
  52         return dev->lstats == NULL ? -ENOMEM : 0;
  53 }
  54
  55 static void nlmon_dev_uninit(struct net_device *dev)
  56 {
  57         free_percpu(dev->lstats);
  58 }
  59
  60 struct nlmon {
  61         struct netlink_tap nt;
  62 };
  63
  64 static int nlmon_open(struct net_device *dev)
  65 {
  66         struct nlmon *nlmon = netdev_priv(dev);
  67
  68         nlmon->nt.dev = dev;
  69         nlmon->nt.module = THIS_MODULE;
  70         return netlink_add_tap(&nlmon->nt);
  71 }
  72
  73 static int nlmon_close(struct net_device *dev)
  74 {
  75         struct nlmon *nlmon = netdev_priv(dev);
  76
  77         return netlink_remove_tap(&nlmon->nt);
  78 }
  79
  80 static struct rtnl_link_stats64 *
  81 nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
  82 {
  83         int i;
  84         u64 bytes = 0, packets = 0;
  85
  86         for_each_possible_cpu(i) {
  87                 const struct pcpu_lstats *nl_stats;
  88                 u64 tbytes, tpackets;
  89                 unsigned int start;
  90
  91                 nl_stats = per_cpu_ptr(dev->lstats, i);
  92
  93                 do {
  94                         start = u64_stats_fetch_begin_bh(&nl_stats->syncp);
  95                         tbytes = nl_stats->bytes;
  96                         tpackets = nl_stats->packets;
  97                 } while (u64_stats_fetch_retry_bh(&nl_stats->syncp, start));
  98
  99                 packets += tpackets;
 100                 bytes += tbytes;
 101         }
 102
 103         stats->rx_packets = packets;
 104         stats->tx_packets = 0;
 105
 106         stats->rx_bytes = bytes;
 107         stats->tx_bytes = 0;
 108
 109         return stats;
 110 }
 111
 112 static u32 always_on(struct net_device *dev)
 113 {
 114         return 1;
 115 }
 116
 117 static const struct ethtool_ops nlmon_ethtool_ops = {
 118         .get_link = always_on,
 119 };
 120
 121 static const struct net_device_ops nlmon_ops = {
 122         .ndo_init = nlmon_dev_init,
 123         .ndo_uninit = nlmon_dev_uninit,
 124         .ndo_open = nlmon_open,
 125         .ndo_stop = nlmon_close,
 126         .ndo_start_xmit = nlmon_xmit,
 127         .ndo_get_stats64 = nlmon_get_stats64,
 128         .ndo_change_mtu = nlmon_change_mtu,
 129 };
 130
 131 static void nlmon_setup(struct net_device *dev)
 132 {
 133         dev->type = ARPHRD_NETLINK;
 134         dev->tx_queue_len = 0;
 135
 136         dev->netdev_ops = &nlmon_ops;
 137         dev->ethtool_ops = &nlmon_ethtool_ops;
 138         dev->destructor = free_netdev;
 139
 140         dev->features = NETIF_F_FRAGLIST | NETIF_F_HIGHDMA;
 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");