tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 int i;
51
52 dev->lstats = alloc_percpu(struct pcpu_lstats);
53
54 for_each_possible_cpu(i) {
55 struct pcpu_lstats *nlmstats;
56 nlmstats = per_cpu_ptr(dev->lstats, i);
57 u64_stats_init(&nlmstats->syncp);
58 }
59
60 return dev->lstats == NULL ? -ENOMEM : 0;
61}
62
63static void nlmon_dev_uninit(struct net_device *dev)
64{
65 free_percpu(dev->lstats);
66}
67
68struct nlmon {
69 struct netlink_tap nt;
70};
71
72static int nlmon_open(struct net_device *dev)
73{
74 struct nlmon *nlmon = netdev_priv(dev);
75
76 nlmon->nt.dev = dev;
77 nlmon->nt.module = THIS_MODULE;
78 return netlink_add_tap(&nlmon->nt);
79}
80
81static int nlmon_close(struct net_device *dev)
82{
83 struct nlmon *nlmon = netdev_priv(dev);
84
85 return netlink_remove_tap(&nlmon->nt);
86}
87
88static struct rtnl_link_stats64 *
89nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
90{
91 int i;
92 u64 bytes = 0, packets = 0;
93
94 for_each_possible_cpu(i) {
95 const struct pcpu_lstats *nl_stats;
96 u64 tbytes, tpackets;
97 unsigned int start;
98
99 nl_stats = per_cpu_ptr(dev->lstats, i);
100
101 do {
102 start = u64_stats_fetch_begin_bh(&nl_stats->syncp);
103 tbytes = nl_stats->bytes;
104 tpackets = nl_stats->packets;
105 } while (u64_stats_fetch_retry_bh(&nl_stats->syncp, start));
106
107 packets += tpackets;
108 bytes += tbytes;
109 }
110
111 stats->rx_packets = packets;
112 stats->tx_packets = 0;
113
114 stats->rx_bytes = bytes;
115 stats->tx_bytes = 0;
116
117 return stats;
118}
119
120static u32 always_on(struct net_device *dev)
121{
122 return 1;
123}
124
125static const struct ethtool_ops nlmon_ethtool_ops = {
126 .get_link = always_on,
127};
128
129static const struct net_device_ops nlmon_ops = {
130 .ndo_init = nlmon_dev_init,
131 .ndo_uninit = nlmon_dev_uninit,
132 .ndo_open = nlmon_open,
133 .ndo_stop = nlmon_close,
134 .ndo_start_xmit = nlmon_xmit,
135 .ndo_get_stats64 = nlmon_get_stats64,
136 .ndo_change_mtu = nlmon_change_mtu,
137};
138
139static void nlmon_setup(struct net_device *dev)
140{
141 dev->type = ARPHRD_NETLINK;
142 dev->tx_queue_len = 0;
143
144 dev->netdev_ops = &nlmon_ops;
145 dev->ethtool_ops = &nlmon_ethtool_ops;
146 dev->destructor = free_netdev;
147
148 dev->features = NETIF_F_FRAGLIST | NETIF_F_HIGHDMA;
149 dev->flags = IFF_NOARP;
150
151 /* That's rather a softlimit here, which, of course,
152 * can be altered. Not a real MTU, but what is to be
153 * expected in most cases.
154 */
155 dev->mtu = NLMSG_GOODSIZE;
156}
157
158static int nlmon_validate(struct nlattr *tb[], struct nlattr *data[])
159{
160 if (tb[IFLA_ADDRESS])
161 return -EINVAL;
162 return 0;
163}
164
165static struct rtnl_link_ops nlmon_link_ops __read_mostly = {
166 .kind = "nlmon",
167 .priv_size = sizeof(struct nlmon),
168 .setup = nlmon_setup,
169 .validate = nlmon_validate,
170};
171
172static __init int nlmon_register(void)
173{
174 return rtnl_link_register(&nlmon_link_ops);
175}
176
177static __exit void nlmon_unregister(void)
178{
179 rtnl_link_unregister(&nlmon_link_ops);
180}
181
182module_init(nlmon_register);
183module_exit(nlmon_unregister);
184
185MODULE_LICENSE("GPL v2");
186MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
187MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>");
188MODULE_DESCRIPTION("Netlink monitoring device");
189MODULE_ALIAS_RTNL_LINK("nlmon");