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