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