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 | |
11 | static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev) |
12 | { |
13 | dev_lstats_add(dev, len: skb->len); |
14 | |
15 | dev_kfree_skb(skb); |
16 | |
17 | return NETDEV_TX_OK; |
18 | } |
19 | |
20 | static 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 | |
26 | static void nlmon_dev_uninit(struct net_device *dev) |
27 | { |
28 | free_percpu(pdata: dev->lstats); |
29 | } |
30 | |
31 | struct nlmon { |
32 | struct netlink_tap nt; |
33 | }; |
34 | |
35 | static 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(nt: &nlmon->nt); |
42 | } |
43 | |
44 | static int nlmon_close(struct net_device *dev) |
45 | { |
46 | struct nlmon *nlmon = netdev_priv(dev); |
47 | |
48 | return netlink_remove_tap(nt: &nlmon->nt); |
49 | } |
50 | |
51 | static void |
52 | nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats) |
53 | { |
54 | u64 packets, bytes; |
55 | |
56 | dev_lstats_read(dev, packets: &packets, bytes: &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 | |
65 | static u32 always_on(struct net_device *dev) |
66 | { |
67 | return 1; |
68 | } |
69 | |
70 | static const struct ethtool_ops nlmon_ethtool_ops = { |
71 | .get_link = always_on, |
72 | }; |
73 | |
74 | static 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 | |
83 | static 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 | |
104 | static 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 | |
112 | static 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 | |
119 | static __init int nlmon_register(void) |
120 | { |
121 | return rtnl_link_register(ops: &nlmon_link_ops); |
122 | } |
123 | |
124 | static __exit void nlmon_unregister(void) |
125 | { |
126 | rtnl_link_unregister(ops: &nlmon_link_ops); |
127 | } |
128 | |
129 | module_init(nlmon_register); |
130 | module_exit(nlmon_unregister); |
131 | |
132 | MODULE_LICENSE("GPL v2" ); |
133 | MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>" ); |
134 | MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>" ); |
135 | MODULE_DESCRIPTION("Netlink monitoring device" ); |
136 | MODULE_ALIAS_RTNL_LINK("nlmon" ); |
137 | |