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         int i;
  51
  52         dev->lstats = alloc_percpu(struct pcpu_lstats);
  53
  54         for_each_possible_cpu(i) {
  55                 struct pcpu_lstats *nlmstats;
  56                 nlmstats = per_cpu_ptr(dev->lstats, i);
  57                 u64_stats_init(&nlmstats->syncp);
  58         }
  59
  60         return dev->lstats == NULL ? -ENOMEM : 0;
  61 }
  62
  63 static void nlmon_dev_uninit(struct net_device *dev)
  64 {
  65         free_percpu(dev->lstats);
  66 }
  67
  68 struct nlmon {
  69         struct netlink_tap nt;
  70 };
  71
  72 static int nlmon_open(struct net_device *dev)
  73 {
  74         struct nlmon *nlmon = netdev_priv(dev);
  75
  76         nlmon->nt.dev = dev;
  77         nlmon->nt.module = THIS_MODULE;
  78         return netlink_add_tap(&nlmon->nt);
  79 }
  80
  81 static int nlmon_close(struct net_device *dev)
  82 {
  83         struct nlmon *nlmon = netdev_priv(dev);
  84
  85         return netlink_remove_tap(&nlmon->nt);
  86 }
  87
  88 static struct rtnl_link_stats64 *
  89 nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
  90 {
  91         int i;
  92         u64 bytes = 0, packets = 0;
  93
  94         for_each_possible_cpu(i) {
  95                 const struct pcpu_lstats *nl_stats;
  96                 u64 tbytes, tpackets;
  97                 unsigned int start;
  98
  99                 nl_stats = per_cpu_ptr(dev->lstats, i);
 100
 101                 do {
 102                         start = u64_stats_fetch_begin_bh(&nl_stats->syncp);
 103                         tbytes = nl_stats->bytes;
 104                         tpackets = nl_stats->packets;
 105                 } while (u64_stats_fetch_retry_bh(&nl_stats->syncp, start));
 106
 107                 packets += tpackets;
 108                 bytes += tbytes;
 109         }
 110
 111         stats->rx_packets = packets;
 112         stats->tx_packets = 0;
 113
 114         stats->rx_bytes = bytes;
 115         stats->tx_bytes = 0;
 116
 117         return stats;
 118 }
 119
 120 static u32 always_on(struct net_device *dev)
 121 {
 122         return 1;
 123 }
 124
 125 static const struct ethtool_ops nlmon_ethtool_ops = {
 126         .get_link = always_on,
 127 };
 128
 129 static const struct net_device_ops nlmon_ops = {
 130         .ndo_init = nlmon_dev_init,
 131         .ndo_uninit = nlmon_dev_uninit,
 132         .ndo_open = nlmon_open,
 133         .ndo_stop = nlmon_close,
 134         .ndo_start_xmit = nlmon_xmit,
 135         .ndo_get_stats64 = nlmon_get_stats64,
 136         .ndo_change_mtu = nlmon_change_mtu,
 137 };
 138
 139 static void nlmon_setup(struct net_device *dev)
 140 {
 141         dev->type = ARPHRD_NETLINK;
 142         dev->tx_queue_len = 0;
 143
 144         dev->netdev_ops = &nlmon_ops;
 145         dev->ethtool_ops = &nlmon_ethtool_ops;
 146         dev->destructor = free_netdev;
 147
 148         dev->features = NETIF_F_FRAGLIST | NETIF_F_HIGHDMA;
 149         dev->flags = IFF_NOARP;
 150
 151         /* That's rather a softlimit here, which, of course,
 152          * can be altered. Not a real MTU, but what is to be
 153          * expected in most cases.
 154          */
 155         dev->mtu = NLMSG_GOODSIZE;
 156 }
 157
 158 static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[])
 159 {
 160         if (tb[IFLA_ADDRESS])
 161                 return -EINVAL;
 162         return 0;
 163 }
 164
 165 static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
 166         .kind                   = "nlmon",
 167         .priv_size              = sizeof(struct nlmon),
 168         .setup                  = nlmon_setup,
 169         .validate               = nlmon_validate,
 170 };
 171
 172 static __init int nlmon_register(void)
 173 {
 174         return rtnl_link_register(&nlmon_link_ops);
 175 }
 176
 177 static __exit void nlmon_unregister(void)
 178 {
 179         rtnl_link_unregister(&nlmon_link_ops);
 180 }
 181
 182 module_init(nlmon_register);
 183 module_exit(nlmon_unregister);
 184
 185 MODULE_LICENSE("GPL v2");
 186 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
 187 MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
 188 MODULE_DESCRIPTION("Netlink monitoring device");
 189 MODULE_ALIAS_RTNL_LINK("nlmon");