xref: /kernel/linux/linux-6.6/drivers/net/nlmon.c (revision 62306a36) 
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
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
20static 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
26static void nlmon_dev_uninit(struct net_device *dev)
27{
28	free_percpu(dev->lstats);
29}
30
31struct nlmon {
32	struct netlink_tap nt;
33};
34
35static 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
44static 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
51static void
52nlmon_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
65static u32 always_on(struct net_device *dev)
66{
67	return 1;
68}
69
70static const struct ethtool_ops nlmon_ethtool_ops = {
71	.get_link = always_on,
72};
73
74static 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
83static 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
104static 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
112static 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
119static __init int nlmon_register(void)
120{
121	return rtnl_link_register(&nlmon_link_ops);
122}
123
124static __exit void nlmon_unregister(void)
125{
126	rtnl_link_unregister(&nlmon_link_ops);
127}
128
129module_init(nlmon_register);
130module_exit(nlmon_unregister);
131
132MODULE_LICENSE("GPL v2");
133MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
134MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
135MODULE_DESCRIPTION("Netlink monitoring device");
136MODULE_ALIAS_RTNL_LINK("nlmon");
137