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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
9struct pcpu_lstats {
10 u64 packets;
11 u64 bytes;
12 struct u64_stats_sync syncp;
13};
14
15static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev)
16{
17 int len = skb->len;
18 struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
19
20 u64_stats_update_begin(&stats->syncp);
21 stats->bytes += len;
22 stats->packets++;
23 u64_stats_update_end(&stats->syncp);
24
25 dev_kfree_skb(skb);
26
27 return NETDEV_TX_OK;
28}
29
30static int nlmon_is_valid_mtu(int new_mtu)
31{
32 /* Note that in netlink we do not really have an upper limit. On
33 * default, we use NLMSG_GOODSIZE. Here at least we should make
34 * sure that it's at least the header size.
35 */
36 return new_mtu >= (int) sizeof(struct nlmsghdr);
37}
38
39static int nlmon_change_mtu(struct net_device *dev, int new_mtu)
40{
41 if (!nlmon_is_valid_mtu(new_mtu))
42 return -EINVAL;
43
44 dev->mtu = new_mtu;
45 return 0;
46}
47
48static int nlmon_dev_init(struct net_device *dev)
49{
50 dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
51 return dev->lstats == NULL ? -ENOMEM : 0;
52}
53
54static void nlmon_dev_uninit(struct net_device *dev)
55{
56 free_percpu(dev->lstats);
57}
58
59struct nlmon {
60 struct netlink_tap nt;
61};
62
63static int nlmon_open(struct net_device *dev)
64{
65 struct nlmon *nlmon = netdev_priv(dev);
66
67 nlmon->nt.dev = dev;
68 nlmon->nt.module = THIS_MODULE;
69 return netlink_add_tap(&nlmon->nt);
70}
71
72static int nlmon_close(struct net_device *dev)
73{
74 struct nlmon *nlmon = netdev_priv(dev);
75
76 return netlink_remove_tap(&nlmon->nt);
77}
78
79static struct rtnl_link_stats64 *
80nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
81{
82 int i;
83 u64 bytes = 0, packets = 0;
84
85 for_each_possible_cpu(i) {
86 const struct pcpu_lstats *nl_stats;
87 u64 tbytes, tpackets;
88 unsigned int start;
89
90 nl_stats = per_cpu_ptr(dev->lstats, i);
91
92 do {
93 start = u64_stats_fetch_begin_irq(&nl_stats->syncp);
94 tbytes = nl_stats->bytes;
95 tpackets = nl_stats->packets;
96 } while (u64_stats_fetch_retry_irq(&nl_stats->syncp, start));
97
98 packets += tpackets;
99 bytes += tbytes;
100 }
101
102 stats->rx_packets = packets;
103 stats->tx_packets = 0;
104
105 stats->rx_bytes = bytes;
106 stats->tx_bytes = 0;
107
108 return stats;
109}
110
111static u32 always_on(struct net_device *dev)
112{
113 return 1;
114}
115
116static const struct ethtool_ops nlmon_ethtool_ops = {
117 .get_link = always_on,
118};
119
120static const struct net_device_ops nlmon_ops = {
121 .ndo_init = nlmon_dev_init,
122 .ndo_uninit = nlmon_dev_uninit,
123 .ndo_open = nlmon_open,
124 .ndo_stop = nlmon_close,
125 .ndo_start_xmit = nlmon_xmit,
126 .ndo_get_stats64 = nlmon_get_stats64,
127 .ndo_change_mtu = nlmon_change_mtu,
128};
129
130static void nlmon_setup(struct net_device *dev)
131{
132 dev->type = ARPHRD_NETLINK;
133 dev->tx_queue_len = 0;
134
135 dev->netdev_ops = &nlmon_ops;
136 dev->ethtool_ops = &nlmon_ethtool_ops;
137 dev->destructor = free_netdev;
138
139 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
140 NETIF_F_HIGHDMA | NETIF_F_LLTX;
141 dev->flags = IFF_NOARP;
142
143 /* That's rather a softlimit here, which, of course,
144 * can be altered. Not a real MTU, but what is to be
145 * expected in most cases.
146 */
147 dev->mtu = NLMSG_GOODSIZE;
148}
149
150static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[])
151{
152 if (tb[IFLA_ADDRESS])
153 return -EINVAL;
154 return 0;
155}
156
157static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
158 .kind = "nlmon",
159 .priv_size = sizeof(struct nlmon),
160 .setup = nlmon_setup,
161 .validate = nlmon_validate,
162};
163
164static __init int nlmon_register(void)
165{
166 return rtnl_link_register(&nlmon_link_ops);
167}
168
169static __exit void nlmon_unregister(void)
170{
171 rtnl_link_unregister(&nlmon_link_ops);
172}
173
174module_init(nlmon_register);
175module_exit(nlmon_unregister);
176
177MODULE_LICENSE("GPL v2");
178MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
179MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
180MODULE_DESCRIPTION("Netlink monitoring device");
181MODULE_ALIAS_RTNL_LINK("nlmon");
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
10static 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
19static 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
25static void nlmon_dev_uninit(struct net_device *dev)
26{
27 free_percpu(dev->lstats);
28}
29
30struct nlmon {
31 struct netlink_tap nt;
32};
33
34static 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
43static 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
50static void
51nlmon_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
64static u32 always_on(struct net_device *dev)
65{
66 return 1;
67}
68
69static const struct ethtool_ops nlmon_ethtool_ops = {
70 .get_link = always_on,
71};
72
73static 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
82static 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
103static 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
111static 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
118static __init int nlmon_register(void)
119{
120 return rtnl_link_register(&nlmon_link_ops);
121}
122
123static __exit void nlmon_unregister(void)
124{
125 rtnl_link_unregister(&nlmon_link_ops);
126}
127
128module_init(nlmon_register);
129module_exit(nlmon_unregister);
130
131MODULE_LICENSE("GPL v2");
132MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
133MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
134MODULE_DESCRIPTION("Netlink monitoring device");
135MODULE_ALIAS_RTNL_LINK("nlmon");