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