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"); 190