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1// SPDX-License-Identifier: GPL-2.0-only2#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 11static 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 20struct nlmon {21 struct netlink_tap nt;22};23 24static int nlmon_open(struct net_device *dev)25{26 struct nlmon *nlmon = netdev_priv(dev);27 28 nlmon->nt.dev = dev;29 nlmon->nt.module = THIS_MODULE;30 return netlink_add_tap(&nlmon->nt);31}32 33static int nlmon_close(struct net_device *dev)34{35 struct nlmon *nlmon = netdev_priv(dev);36 37 return netlink_remove_tap(&nlmon->nt);38}39 40static void41nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)42{43 dev_lstats_read(dev, &stats->rx_packets, &stats->rx_bytes);44}45 46static u32 always_on(struct net_device *dev)47{48 return 1;49}50 51static const struct ethtool_ops nlmon_ethtool_ops = {52 .get_link = always_on,53};54 55static const struct net_device_ops nlmon_ops = {56 .ndo_open = nlmon_open,57 .ndo_stop = nlmon_close,58 .ndo_start_xmit = nlmon_xmit,59 .ndo_get_stats64 = nlmon_get_stats64,60};61 62static void nlmon_setup(struct net_device *dev)63{64 dev->type = ARPHRD_NETLINK;65 dev->priv_flags |= IFF_NO_QUEUE;66 dev->lltx = true;67 68 dev->netdev_ops = &nlmon_ops;69 dev->ethtool_ops = &nlmon_ethtool_ops;70 dev->needs_free_netdev = true;71 72 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HIGHDMA;73 dev->flags = IFF_NOARP;74 dev->pcpu_stat_type = NETDEV_PCPU_STAT_LSTATS;75 76 /* That's rather a softlimit here, which, of course,77 * can be altered. Not a real MTU, but what is to be78 * expected in most cases.79 */80 dev->mtu = NLMSG_GOODSIZE;81 dev->min_mtu = sizeof(struct nlmsghdr);82}83 84static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[],85 struct netlink_ext_ack *extack)86{87 if (tb[IFLA_ADDRESS])88 return -EINVAL;89 return 0;90}91 92static struct rtnl_link_ops nlmon_link_ops __read_mostly = {93 .kind = "nlmon",94 .priv_size = sizeof(struct nlmon),95 .setup = nlmon_setup,96 .validate = nlmon_validate,97};98 99static __init int nlmon_register(void)100{101 return rtnl_link_register(&nlmon_link_ops);102}103 104static __exit void nlmon_unregister(void)105{106 rtnl_link_unregister(&nlmon_link_ops);107}108 109module_init(nlmon_register);110module_exit(nlmon_unregister);111 112MODULE_LICENSE("GPL v2");113MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");114MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");115MODULE_DESCRIPTION("Netlink monitoring device");116MODULE_ALIAS_RTNL_LINK("nlmon");117