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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/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 void
41nlmon_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
67 dev->netdev_ops = &nlmon_ops;
68 dev->ethtool_ops = &nlmon_ethtool_ops;
69 dev->needs_free_netdev = true;
70
71 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
72 NETIF_F_HIGHDMA | NETIF_F_LLTX;
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 be
78 * 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");