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 dev->lstats = alloc_percpu(struct pcpu_lstats); 51 52 return dev->lstats == NULL ? -ENOMEM : 0; 53 } 54 55 static void nlmon_dev_uninit(struct net_device *dev) 56 { 57 free_percpu(dev->lstats); 58 } 59 60 struct nlmon { 61 struct netlink_tap nt; 62 }; 63 64 static int nlmon_open(struct net_device *dev) 65 { 66 struct nlmon *nlmon = netdev_priv(dev); 67 68 nlmon->nt.dev = dev; 69 nlmon->nt.module = THIS_MODULE; 70 return netlink_add_tap(&nlmon->nt); 71 } 72 73 static int nlmon_close(struct net_device *dev) 74 { 75 struct nlmon *nlmon = netdev_priv(dev); 76 77 return netlink_remove_tap(&nlmon->nt); 78 } 79 80 static struct rtnl_link_stats64 * 81 nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats) 82 { 83 int i; 84 u64 bytes = 0, packets = 0; 85 86 for_each_possible_cpu(i) { 87 const struct pcpu_lstats *nl_stats; 88 u64 tbytes, tpackets; 89 unsigned int start; 90 91 nl_stats = per_cpu_ptr(dev->lstats, i); 92 93 do { 94 start = u64_stats_fetch_begin_bh(&nl_stats->syncp); 95 tbytes = nl_stats->bytes; 96 tpackets = nl_stats->packets; 97 } while (u64_stats_fetch_retry_bh(&nl_stats->syncp, start)); 98 99 packets += tpackets; 100 bytes += tbytes; 101 } 102 103 stats->rx_packets = packets; 104 stats->tx_packets = 0; 105 106 stats->rx_bytes = bytes; 107 stats->tx_bytes = 0; 108 109 return stats; 110 } 111 112 static u32 always_on(struct net_device *dev) 113 { 114 return 1; 115 } 116 117 static const struct ethtool_ops nlmon_ethtool_ops = { 118 .get_link = always_on, 119 }; 120 121 static const struct net_device_ops nlmon_ops = { 122 .ndo_init = nlmon_dev_init, 123 .ndo_uninit = nlmon_dev_uninit, 124 .ndo_open = nlmon_open, 125 .ndo_stop = nlmon_close, 126 .ndo_start_xmit = nlmon_xmit, 127 .ndo_get_stats64 = nlmon_get_stats64, 128 .ndo_change_mtu = nlmon_change_mtu, 129 }; 130 131 static void nlmon_setup(struct net_device *dev) 132 { 133 dev->type = ARPHRD_NETLINK; 134 dev->tx_queue_len = 0; 135 136 dev->netdev_ops = &nlmon_ops; 137 dev->ethtool_ops = &nlmon_ethtool_ops; 138 dev->destructor = free_netdev; 139 140 dev->features = NETIF_F_FRAGLIST | NETIF_F_HIGHDMA; 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 } 149 150 static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[]) 151 { 152 if (tb[IFLA_ADDRESS]) 153 return -EINVAL; 154 return 0; 155 } 156 157 static 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 }; 163 164 static __init int nlmon_register(void) 165 { 166 return rtnl_link_register(&nlmon_link_ops); 167 } 168 169 static __exit void nlmon_unregister(void) 170 { 171 rtnl_link_unregister(&nlmon_link_ops); 172 } 173 174 module_init(nlmon_register); 175 module_exit(nlmon_unregister); 176 177 MODULE_LICENSE("GPL v2"); 178 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>"); 179 MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>"); 180 MODULE_DESCRIPTION("Netlink monitoring device"); 181 MODULE_ALIAS_RTNL_LINK("nlmon"); 182