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
nlmon_xmit(struct sk_buff * skb,struct net_device * dev)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
nlmon_dev_init(struct net_device * dev)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
nlmon_dev_uninit(struct net_device * dev)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
nlmon_open(struct net_device * dev)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
nlmon_close(struct net_device * dev)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
nlmon_get_stats64(struct net_device * dev,struct rtnl_link_stats64 * stats)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
always_on(struct net_device * dev)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
nlmon_setup(struct net_device * dev)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
nlmon_validate(struct nlattr * tb[],struct nlattr * data[],struct netlink_ext_ack * extack)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
nlmon_register(void)119 static __init int nlmon_register(void)
120 {
121 return rtnl_link_register(&nlmon_link_ops);
122 }
123
nlmon_unregister(void)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