LXR linux/drivers/net/nlmon.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2#include <linux/module.h>
   3#include <linux/kernel.h>
   4#include <linux/netdevice.h>
   5#include <linux/netlink.h>
   6#include <net/net_namespace.h>
   7#include <linux/if_arp.h>
   8#include <net/rtnetlink.h>
   9
  10static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
  11{
  12        int len = skb->len;
  13        struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
  14
  15        u64_stats_update_begin(&stats->syncp);
  16        stats->bytes += len;
  17        stats->packets++;
  18        u64_stats_update_end(&stats->syncp);
  19
  20        dev_kfree_skb(skb);
  21
  22        return NETDEV_TX_OK;
  23}
  24
  25static int nlmon_dev_init(struct net_device *dev)
  26{
  27        dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
  28        return dev->lstats == NULL ? -ENOMEM : 0;
  29}
  30
  31static void nlmon_dev_uninit(struct net_device *dev)
  32{
  33        free_percpu(dev->lstats);
  34}
  35
  36struct nlmon {
  37        struct netlink_tap nt;
  38};
  39
  40static int nlmon_open(struct net_device *dev)
  41{
  42        struct nlmon *nlmon = netdev_priv(dev);
  43
  44        nlmon->nt.dev = dev;
  45        nlmon->nt.module = THIS_MODULE;
  46        return netlink_add_tap(&nlmon->nt);
  47}
  48
  49static int nlmon_close(struct net_device *dev)
  50{
  51        struct nlmon *nlmon = netdev_priv(dev);
  52
  53        return netlink_remove_tap(&nlmon->nt);
  54}
  55
  56static void
  57nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
  58{
  59        int i;
  60        u64 bytes = 0, packets = 0;
  61
  62        for_each_possible_cpu(i) {
  63                const struct pcpu_lstats *nl_stats;
  64                u64 tbytes, tpackets;
  65                unsigned int start;
  66
  67                nl_stats = per_cpu_ptr(dev->lstats, i);
  68
  69                do {
  70                        start = u64_stats_fetch_begin_irq(&nl_stats->syncp);
  71                        tbytes = nl_stats->bytes;
  72                        tpackets = nl_stats->packets;
  73                } while (u64_stats_fetch_retry_irq(&nl_stats->syncp, start));
  74
  75                packets += tpackets;
  76                bytes += tbytes;
  77        }
  78
  79        stats->rx_packets = packets;
  80        stats->tx_packets = 0;
  81
  82        stats->rx_bytes = bytes;
  83        stats->tx_bytes = 0;
  84}
  85
  86static u32 always_on(struct net_device *dev)
  87{
  88        return 1;
  89}
  90
  91static const struct ethtool_ops nlmon_ethtool_ops = {
  92        .get_link = always_on,
  93};
  94
  95static const struct net_device_ops nlmon_ops = {
  96        .ndo_init = nlmon_dev_init,
  97        .ndo_uninit = nlmon_dev_uninit,
  98        .ndo_open = nlmon_open,
  99        .ndo_stop = nlmon_close,
 100        .ndo_start_xmit = nlmon_xmit,
 101        .ndo_get_stats64 = nlmon_get_stats64,
 102};
 103
 104static void nlmon_setup(struct net_device *dev)
 105{
 106        dev->type = ARPHRD_NETLINK;
 107        dev->priv_flags |= IFF_NO_QUEUE;
 108
 109        dev->netdev_ops = &nlmon_ops;
 110        dev->ethtool_ops = &nlmon_ethtool_ops;
 111        dev->needs_free_netdev = true;
 112
 113        dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
 114                        NETIF_F_HIGHDMA | NETIF_F_LLTX;
 115        dev->flags = IFF_NOARP;
 116
 117        /* That's rather a softlimit here, which, of course,
 118         * can be altered. Not a real MTU, but what is to be
 119         * expected in most cases.
 120         */
 121        dev->mtu = NLMSG_GOODSIZE;
 122        dev->min_mtu = sizeof(struct nlmsghdr);
 123}
 124
 125static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[],
 126                          struct netlink_ext_ack *extack)
 127{
 128        if (tb[IFLA_ADDRESS])
 129                return -EINVAL;
 130        return 0;
 131}
 132
 133static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
 134        .kind                   = "nlmon",
 135        .priv_size              = sizeof(struct nlmon),
 136        .setup                  = nlmon_setup,
 137        .validate               = nlmon_validate,
 138};
 139
 140static __init int nlmon_register(void)
 141{
 142        return rtnl_link_register(&nlmon_link_ops);
 143}
 144
 145static __exit void nlmon_unregister(void)
 146{
 147        rtnl_link_unregister(&nlmon_link_ops);
 148}
 149
 150module_init(nlmon_register);
 151module_exit(nlmon_unregister);
 152
 153MODULE_LICENSE("GPL v2");
 154MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
 155MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
 156MODULE_DESCRIPTION("Netlink monitoring device");
 157MODULE_ALIAS_RTNL_LINK("nlmon");
 158