LXR linux/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
   9struct pcpu_lstats {
  10        u64 packets;
  11        u64 bytes;
  12        struct u64_stats_sync syncp;
  13};
  14
  15static 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
  30static 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
  39static 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
  48static 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
  54static void nlmon_dev_uninit(struct net_device *dev)
  55{
  56        free_percpu(dev->lstats);
  57}
  58
  59struct nlmon {
  60        struct netlink_tap nt;
  61};
  62
  63static 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
  72static 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
  79static struct rtnl_link_stats64 *
  80nlmon_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
 111static u32 always_on(struct net_device *dev)
 112{
 113        return 1;
 114}
 115
 116static const struct ethtool_ops nlmon_ethtool_ops = {
 117        .get_link = always_on,
 118};
 119
 120static 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
 130static 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
 150static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[])
 151{
 152        if (tb[IFLA_ADDRESS])
 153                return -EINVAL;
 154        return 0;
 155}
 156
 157static 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
 164static __init int nlmon_register(void)
 165{
 166        return rtnl_link_register(&nlmon_link_ops);
 167}
 168
 169static __exit void nlmon_unregister(void)
 170{
 171        rtnl_link_unregister(&nlmon_link_ops);
 172}
 173
 174module_init(nlmon_register);
 175module_exit(nlmon_unregister);
 176
 177MODULE_LICENSE("GPL v2");
 178MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
 179MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
 180MODULE_DESCRIPTION("Netlink monitoring device");
 181MODULE_ALIAS_RTNL_LINK("nlmon");
 182