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