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e4fc408e DB |
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 | ||
8 | struct pcpu_lstats { | |
9 | u64 packets; | |
10 | u64 bytes; | |
11 | struct u64_stats_sync syncp; | |
12 | }; | |
13 | ||
14 | static netdev_tx_t nlmon_xmit(struct sk_buff *skb, struct net_device *dev) | |
15 | { | |
16 | int len = skb->len; | |
17 | struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats); | |
18 | ||
19 | u64_stats_update_begin(&stats->syncp); | |
20 | stats->bytes += len; | |
21 | stats->packets++; | |
22 | u64_stats_update_end(&stats->syncp); | |
23 | ||
24 | dev_kfree_skb(skb); | |
25 | ||
26 | return NETDEV_TX_OK; | |
27 | } | |
28 | ||
29 | static int nlmon_is_valid_mtu(int new_mtu) | |
30 | { | |
3b233fe0 DB |
31 | /* Note that in netlink we do not really have an upper limit. On |
32 | * default, we use NLMSG_GOODSIZE. Here at least we should make | |
33 | * sure that it's at least the header size. | |
34 | */ | |
35 | return new_mtu >= (int) sizeof(struct nlmsghdr); | |
e4fc408e DB |
36 | } |
37 | ||
38 | static int nlmon_change_mtu(struct net_device *dev, int new_mtu) | |
39 | { | |
40 | if (!nlmon_is_valid_mtu(new_mtu)) | |
41 | return -EINVAL; | |
42 | ||
43 | dev->mtu = new_mtu; | |
44 | return 0; | |
45 | } | |
46 | ||
47 | static int nlmon_dev_init(struct net_device *dev) | |
48 | { | |
49 | dev->lstats = alloc_percpu(struct pcpu_lstats); | |
50 | ||
51 | return dev->lstats == NULL ? -ENOMEM : 0; | |
52 | } | |
53 | ||
54 | static void nlmon_dev_uninit(struct net_device *dev) | |
55 | { | |
56 | free_percpu(dev->lstats); | |
57 | } | |
58 | ||
59 | static struct netlink_tap nlmon_tap; | |
60 | ||
61 | static int nlmon_open(struct net_device *dev) | |
62 | { | |
63 | return netlink_add_tap(&nlmon_tap); | |
64 | } | |
65 | ||
66 | static int nlmon_close(struct net_device *dev) | |
67 | { | |
68 | return netlink_remove_tap(&nlmon_tap); | |
69 | } | |
70 | ||
71 | static struct rtnl_link_stats64 * | |
72 | nlmon_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats) | |
73 | { | |
74 | int i; | |
75 | u64 bytes = 0, packets = 0; | |
76 | ||
77 | for_each_possible_cpu(i) { | |
78 | const struct pcpu_lstats *nl_stats; | |
79 | u64 tbytes, tpackets; | |
80 | unsigned int start; | |
81 | ||
82 | nl_stats = per_cpu_ptr(dev->lstats, i); | |
83 | ||
84 | do { | |
85 | start = u64_stats_fetch_begin_bh(&nl_stats->syncp); | |
86 | tbytes = nl_stats->bytes; | |
87 | tpackets = nl_stats->packets; | |
88 | } while (u64_stats_fetch_retry_bh(&nl_stats->syncp, start)); | |
89 | ||
90 | packets += tpackets; | |
91 | bytes += tbytes; | |
92 | } | |
93 | ||
94 | stats->rx_packets = packets; | |
95 | stats->tx_packets = 0; | |
96 | ||
97 | stats->rx_bytes = bytes; | |
98 | stats->tx_bytes = 0; | |
99 | ||
100 | return stats; | |
101 | } | |
102 | ||
103 | static u32 always_on(struct net_device *dev) | |
104 | { | |
105 | return 1; | |
106 | } | |
107 | ||
108 | static const struct ethtool_ops nlmon_ethtool_ops = { | |
109 | .get_link = always_on, | |
110 | }; | |
111 | ||
112 | static const struct net_device_ops nlmon_ops = { | |
113 | .ndo_init = nlmon_dev_init, | |
114 | .ndo_uninit = nlmon_dev_uninit, | |
115 | .ndo_open = nlmon_open, | |
116 | .ndo_stop = nlmon_close, | |
117 | .ndo_start_xmit = nlmon_xmit, | |
118 | .ndo_get_stats64 = nlmon_get_stats64, | |
119 | .ndo_change_mtu = nlmon_change_mtu, | |
120 | }; | |
121 | ||
122 | static struct netlink_tap nlmon_tap __read_mostly = { | |
123 | .module = THIS_MODULE, | |
124 | }; | |
125 | ||
126 | static void nlmon_setup(struct net_device *dev) | |
127 | { | |
128 | dev->type = ARPHRD_NETLINK; | |
129 | dev->tx_queue_len = 0; | |
130 | ||
131 | dev->netdev_ops = &nlmon_ops; | |
132 | dev->ethtool_ops = &nlmon_ethtool_ops; | |
133 | dev->destructor = free_netdev; | |
134 | ||
135 | dev->features = NETIF_F_FRAGLIST | NETIF_F_HIGHDMA; | |
136 | dev->flags = IFF_NOARP; | |
137 | ||
138 | /* That's rather a softlimit here, which, of course, | |
139 | * can be altered. Not a real MTU, but what is to be | |
140 | * expected in most cases. | |
141 | */ | |
142 | dev->mtu = NLMSG_GOODSIZE; | |
143 | } | |
144 | ||
145 | static __init int nlmon_register(void) | |
146 | { | |
147 | int err; | |
148 | struct net_device *nldev; | |
149 | ||
150 | nldev = nlmon_tap.dev = alloc_netdev(0, "netlink", nlmon_setup); | |
151 | if (unlikely(nldev == NULL)) | |
152 | return -ENOMEM; | |
153 | ||
154 | err = register_netdev(nldev); | |
155 | if (unlikely(err)) | |
156 | free_netdev(nldev); | |
157 | ||
158 | return err; | |
159 | } | |
160 | ||
161 | static __exit void nlmon_unregister(void) | |
162 | { | |
163 | struct net_device *nldev = nlmon_tap.dev; | |
164 | ||
165 | unregister_netdev(nldev); | |
166 | } | |
167 | ||
168 | module_init(nlmon_register); | |
169 | module_exit(nlmon_unregister); | |
170 | ||
171 | MODULE_LICENSE("GPL v2"); | |
172 | MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>"); | |
173 | MODULE_AUTHOR("Mathieu Geli <geli@enseirb.fr>"); | |
174 | MODULE_DESCRIPTION("Netlink monitoring device"); |