1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <linux/ethtool.h> 3 #include <linux/module.h> 4 #include <linux/kernel.h> 5 #include <linux/netdevice.h> 6 #include <linux/netlink.h> 7 #include <net/net_namespace.h> 8 #include <linux/if_arp.h> 9 #include <net/rtnetlink.h> 10 11 static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev) 12 { 13 dev_lstats_add(dev, skb->len); 14 15 dev_kfree_skb(skb); 16 17 return NETDEV_TX_OK; 18 } 19 20 static int nlmon_dev_init(struct net_device *dev) 21 { 22 dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats); 23 return dev->lstats == NULL ? -ENOMEM : 0; 24 } 25 26 static void nlmon_dev_uninit(struct net_device *dev) 27 { 28 free_percpu(dev->lstats); 29 } 30 31 struct nlmon { 32 struct netlink_tap nt; 33 }; 34 35 static int nlmon_open(struct net_device *dev) 36 { 37 struct nlmon *nlmon = netdev_priv(dev); 38 39 nlmon->nt.dev = dev; 40 nlmon->nt.module = THIS_MODULE; 41 return netlink_add_tap(&nlmon->nt); 42 } 43 44 static int nlmon_close(struct net_device *dev) 45 { 46 struct nlmon *nlmon = netdev_priv(dev); 47 48 return netlink_remove_tap(&nlmon->nt); 49 } 50 51 static void 52 nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats) 53 { 54 u64 packets, bytes; 55 56 dev_lstats_read(dev, &packets, &bytes); 57 58 stats->rx_packets = packets; 59 stats->tx_packets = 0; 60 61 stats->rx_bytes = bytes; 62 stats->tx_bytes = 0; 63 } 64 65 static u32 always_on(struct net_device *dev) 66 { 67 return 1; 68 } 69 70 static const struct ethtool_ops nlmon_ethtool_ops = { 71 .get_link = always_on, 72 }; 73 74 static const struct net_device_ops nlmon_ops = { 75 .ndo_init = nlmon_dev_init, 76 .ndo_uninit = nlmon_dev_uninit, 77 .ndo_open = nlmon_open, 78 .ndo_stop = nlmon_close, 79 .ndo_start_xmit = nlmon_xmit, 80 .ndo_get_stats64 = nlmon_get_stats64, 81 }; 82 83 static void nlmon_setup(struct net_device *dev) 84 { 85 dev->type = ARPHRD_NETLINK; 86 dev->priv_flags |= IFF_NO_QUEUE; 87 88 dev->netdev_ops = &nlmon_ops; 89 dev->ethtool_ops = &nlmon_ethtool_ops; 90 dev->needs_free_netdev = true; 91 92 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST | 93 NETIF_F_HIGHDMA | NETIF_F_LLTX; 94 dev->flags = IFF_NOARP; 95 96 /* That's rather a softlimit here, which, of course, 97 * can be altered. Not a real MTU, but what is to be 98 * expected in most cases. 99 */ 100 dev->mtu = NLMSG_GOODSIZE; 101 dev->min_mtu = sizeof(struct nlmsghdr); 102 } 103 104 static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[], 105 struct netlink_ext_ack *extack) 106 { 107 if (tb[IFLA_ADDRESS]) 108 return -EINVAL; 109 return 0; 110 } 111 112 static struct rtnl_link_ops nlmon_link_ops __read_mostly = { 113 .kind = "nlmon", 114 .priv_size = sizeof(struct nlmon), 115 .setup = nlmon_setup, 116 .validate = nlmon_validate, 117 }; 118 119 static __init int nlmon_register(void) 120 { 121 return rtnl_link_register(&nlmon_link_ops); 122 } 123 124 static __exit void nlmon_unregister(void) 125 { 126 rtnl_link_unregister(&nlmon_link_ops); 127 } 128 129 module_init(nlmon_register); 130 module_exit(nlmon_unregister); 131 132 MODULE_LICENSE("GPL v2"); 133 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>"); 134 MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>"); 135 MODULE_DESCRIPTION("Netlink monitoring device"); 136 MODULE_ALIAS_RTNL_LINK("nlmon"); 137