1#include <linux/module.h>
2#include <linux/kernel.h>
3#include <linux/netdevice.h>
4#include <linux/netlink.h>
5#include <net/net_namespace.h>
6#include <linux/if_arp.h>
7#include <net/rtnetlink.h>
8
9static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
10{
11 int len = skb->len;
12 struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
13
14 u64_stats_update_begin(&stats->syncp);
15 stats->bytes += len;
16 stats->packets++;
17 u64_stats_update_end(&stats->syncp);
18
19 dev_kfree_skb(skb);
20
21 return NETDEV_TX_OK;
22}
23
24static int nlmon_dev_init(struct net_device *dev)
25{
26 dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
27 return dev->lstats == NULL ? -ENOMEM : 0;
28}
29
30static void nlmon_dev_uninit(struct net_device *dev)
31{
32 free_percpu(dev->lstats);
33}
34
35struct nlmon {
36 struct netlink_tap nt;
37};
38
39static int nlmon_open(struct net_device *dev)
40{
41 struct nlmon *nlmon = netdev_priv(dev);
42
43 nlmon->nt.dev = dev;
44 nlmon->nt.module = THIS_MODULE;
45 return netlink_add_tap(&nlmon->nt);
46}
47
48static int nlmon_close(struct net_device *dev)
49{
50 struct nlmon *nlmon = netdev_priv(dev);
51
52 return netlink_remove_tap(&nlmon->nt);
53}
54
55static void
56nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
57{
58 int i;
59 u64 bytes = 0, packets = 0;
60
61 for_each_possible_cpu(i) {
62 const struct pcpu_lstats *nl_stats;
63 u64 tbytes, tpackets;
64 unsigned int start;
65
66 nl_stats = per_cpu_ptr(dev->lstats, i);
67
68 do {
69 start = u64_stats_fetch_begin_irq(&nl_stats->syncp);
70 tbytes = nl_stats->bytes;
71 tpackets = nl_stats->packets;
72 } while (u64_stats_fetch_retry_irq(&nl_stats->syncp, start));
73
74 packets += tpackets;
75 bytes += tbytes;
76 }
77
78 stats->rx_packets = packets;
79 stats->tx_packets = 0;
80
81 stats->rx_bytes = bytes;
82 stats->tx_bytes = 0;
83}
84
85static u32 always_on(struct net_device *dev)
86{
87 return 1;
88}
89
90static const struct ethtool_ops nlmon_ethtool_ops = {
91 .get_link = always_on,
92};
93
94static const struct net_device_ops nlmon_ops = {
95 .ndo_init = nlmon_dev_init,
96 .ndo_uninit = nlmon_dev_uninit,
97 .ndo_open = nlmon_open,
98 .ndo_stop = nlmon_close,
99 .ndo_start_xmit = nlmon_xmit,
100 .ndo_get_stats64 = nlmon_get_stats64,
101};
102
103static void nlmon_setup(struct net_device *dev)
104{
105 dev->type = ARPHRD_NETLINK;
106 dev->priv_flags |= IFF_NO_QUEUE;
107
108 dev->netdev_ops = &nlmon_ops;
109 dev->ethtool_ops = &nlmon_ethtool_ops;
110 dev->needs_free_netdev = true;
111
112 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
113 NETIF_F_HIGHDMA | NETIF_F_LLTX;
114 dev->flags = IFF_NOARP;
115
116 /* That's rather a softlimit here, which, of course,
117 * can be altered. Not a real MTU, but what is to be
118 * expected in most cases.
119 */
120 dev->mtu = NLMSG_GOODSIZE;
121 dev->min_mtu = sizeof(struct nlmsghdr);
122}
123
124static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[],
125 struct netlink_ext_ack *extack)
126{
127 if (tb[IFLA_ADDRESS])
128 return -EINVAL;
129 return 0;
130}
131
132static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
133 .kind = "nlmon",
134 .priv_size = sizeof(struct nlmon),
135 .setup = nlmon_setup,
136 .validate = nlmon_validate,
137};
138
139static __init int nlmon_register(void)
140{
141 return rtnl_link_register(&nlmon_link_ops);
142}
143
144static __exit void nlmon_unregister(void)
145{
146 rtnl_link_unregister(&nlmon_link_ops);
147}
148
149module_init(nlmon_register);
150module_exit(nlmon_unregister);
151
152MODULE_LICENSE("GPL v2");
153MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
154MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
155MODULE_DESCRIPTION("Netlink monitoring device");
156MODULE_ALIAS_RTNL_LINK("nlmon");
157