blob: 442d91a2747b9d8136dd5809ec3d192fc8c1e04c [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* dummy.c: a dummy net driver
2
3 The purpose of this driver is to provide a device to point a
4 route through, but not to actually transmit packets.
5
6 Why? If you have a machine whose only connection is an occasional
7 PPP/SLIP/PLIP link, you can only connect to your own hostname
8 when the link is up. Otherwise you have to use localhost.
9 This isn't very consistent.
10
11 One solution is to set up a dummy link using PPP/SLIP/PLIP,
12 but this seems (to me) too much overhead for too little gain.
13 This driver provides a small alternative. Thus you can do
Jeff Garzik6aa20a22006-09-13 13:24:59 -040014
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 [when not running slip]
16 ifconfig dummy slip.addr.ess.here up
17 [to go to slip]
18 ifconfig dummy down
19 dip whatever
20
21 This was written by looking at Donald Becker's skeleton driver
22 and the loopback driver. I then threw away anything that didn't
23 apply! Thanks to Alan Cox for the key clue on what to do with
24 misguided packets.
25
26 Nick Holloway, 27th May 1994
27 [I tweaked this explanation a little but that's all]
28 Alan Cox, 30th May 1994
29*/
30
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <linux/module.h>
32#include <linux/kernel.h>
33#include <linux/netdevice.h>
34#include <linux/etherdevice.h>
35#include <linux/init.h>
36#include <linux/moduleparam.h>
Patrick McHardy206c9fb2007-06-13 12:04:20 -070037#include <linux/rtnetlink.h>
Patrick McHardy5d5cb172007-06-13 12:04:34 -070038#include <net/rtnetlink.h>
Eric Dumazet6d81f412010-09-27 20:50:33 +000039#include <linux/u64_stats_sync.h>
Patrick McHardy206c9fb2007-06-13 12:04:20 -070040
Linus Torvalds1da177e2005-04-16 15:20:36 -070041static int numdummies = 1;
42
Linus Torvalds1da177e2005-04-16 15:20:36 -070043static int dummy_set_address(struct net_device *dev, void *p)
44{
45 struct sockaddr *sa = p;
46
Jeff Garzik6aa20a22006-09-13 13:24:59 -040047 if (!is_valid_ether_addr(sa->sa_data))
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 return -EADDRNOTAVAIL;
Jeff Garzik6aa20a22006-09-13 13:24:59 -040049
Danny Kukawka7ce5d222012-02-15 06:45:40 +000050 dev->addr_assign_type &= ~NET_ADDR_RANDOM;
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN);
52 return 0;
53}
54
55/* fake multicast ability */
56static void set_multicast_list(struct net_device *dev)
57{
58}
59
Eric Dumazet6d81f412010-09-27 20:50:33 +000060struct pcpu_dstats {
61 u64 tx_packets;
62 u64 tx_bytes;
63 struct u64_stats_sync syncp;
64};
65
66static struct rtnl_link_stats64 *dummy_get_stats64(struct net_device *dev,
67 struct rtnl_link_stats64 *stats)
68{
69 int i;
70
71 for_each_possible_cpu(i) {
72 const struct pcpu_dstats *dstats;
73 u64 tbytes, tpackets;
74 unsigned int start;
75
76 dstats = per_cpu_ptr(dev->dstats, i);
77 do {
78 start = u64_stats_fetch_begin(&dstats->syncp);
79 tbytes = dstats->tx_bytes;
80 tpackets = dstats->tx_packets;
81 } while (u64_stats_fetch_retry(&dstats->syncp, start));
82 stats->tx_bytes += tbytes;
83 stats->tx_packets += tpackets;
84 }
85 return stats;
86}
Stephen Hemminger424efe92009-08-31 19:50:51 +000087
88static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev)
89{
Eric Dumazet6d81f412010-09-27 20:50:33 +000090 struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats);
91
92 u64_stats_update_begin(&dstats->syncp);
93 dstats->tx_packets++;
94 dstats->tx_bytes += skb->len;
95 u64_stats_update_end(&dstats->syncp);
Stephen Hemminger424efe92009-08-31 19:50:51 +000096
97 dev_kfree_skb(skb);
98 return NETDEV_TX_OK;
99}
100
Eric Dumazet6d81f412010-09-27 20:50:33 +0000101static int dummy_dev_init(struct net_device *dev)
102{
103 dev->dstats = alloc_percpu(struct pcpu_dstats);
104 if (!dev->dstats)
105 return -ENOMEM;
106
107 return 0;
108}
109
Hiroaki SHIMODA890fdf22012-04-15 13:26:01 +0000110static void dummy_dev_uninit(struct net_device *dev)
Eric Dumazet6d81f412010-09-27 20:50:33 +0000111{
112 free_percpu(dev->dstats);
Eric Dumazet6d81f412010-09-27 20:50:33 +0000113}
114
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800115static const struct net_device_ops dummy_netdev_ops = {
Eric Dumazet6d81f412010-09-27 20:50:33 +0000116 .ndo_init = dummy_dev_init,
Hiroaki SHIMODA890fdf22012-04-15 13:26:01 +0000117 .ndo_uninit = dummy_dev_uninit,
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800118 .ndo_start_xmit = dummy_xmit,
119 .ndo_validate_addr = eth_validate_addr,
Jiri Pirkoafc4b132011-08-16 06:29:01 +0000120 .ndo_set_rx_mode = set_multicast_list,
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800121 .ndo_set_mac_address = dummy_set_address,
Eric Dumazet6d81f412010-09-27 20:50:33 +0000122 .ndo_get_stats64 = dummy_get_stats64,
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800123};
124
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700125static void dummy_setup(struct net_device *dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126{
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800127 ether_setup(dev);
128
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 /* Initialize the device structure. */
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -0800130 dev->netdev_ops = &dummy_netdev_ops;
Hiroaki SHIMODA890fdf22012-04-15 13:26:01 +0000131 dev->destructor = free_netdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132
133 /* Fill in device structure with ethernet-generic values. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 dev->tx_queue_len = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 dev->flags |= IFF_NOARP;
136 dev->flags &= ~IFF_MULTICAST;
Eric Dumazet6d81f412010-09-27 20:50:33 +0000137 dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO;
Michał Mirosław34324dc2011-11-15 15:29:55 +0000138 dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX;
Danny Kukawka7ce5d222012-02-15 06:45:40 +0000139 eth_hw_addr_random(dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140}
Eric Dumazet6d81f412010-09-27 20:50:33 +0000141
Patrick McHardy0e068772007-07-11 19:42:31 -0700142static int dummy_validate(struct nlattr *tb[], struct nlattr *data[])
143{
144 if (tb[IFLA_ADDRESS]) {
145 if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
146 return -EINVAL;
147 if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
148 return -EADDRNOTAVAIL;
149 }
150 return 0;
151}
152
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700153static struct rtnl_link_ops dummy_link_ops __read_mostly = {
154 .kind = "dummy",
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700155 .setup = dummy_setup,
Patrick McHardy0e068772007-07-11 19:42:31 -0700156 .validate = dummy_validate,
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700157};
158
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159/* Number of dummy devices to be set up by this module. */
160module_param(numdummies, int, 0);
161MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
162
Patrick McHardy206c9fb2007-06-13 12:04:20 -0700163static int __init dummy_init_one(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164{
165 struct net_device *dev_dummy;
166 int err;
167
Patrick McHardy2d85cba2007-07-11 19:42:13 -0700168 dev_dummy = alloc_netdev(0, "dummy%d", dummy_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 if (!dev_dummy)
170 return -ENOMEM;
171
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700172 dev_dummy->rtnl_link_ops = &dummy_link_ops;
173 err = register_netdevice(dev_dummy);
174 if (err < 0)
175 goto err;
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700176 return 0;
177
178err:
179 free_netdev(dev_dummy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 return err;
181}
182
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183static int __init dummy_init_module(void)
Jeff Garzik6aa20a22006-09-13 13:24:59 -0400184{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 int i, err = 0;
Patrick McHardy206c9fb2007-06-13 12:04:20 -0700186
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700187 rtnl_lock();
188 err = __rtnl_link_register(&dummy_link_ops);
189
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 for (i = 0; i < numdummies && !err; i++)
Patrick McHardy206c9fb2007-06-13 12:04:20 -0700191 err = dummy_init_one();
Patrick McHardy2d85cba2007-07-11 19:42:13 -0700192 if (err < 0)
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700193 __rtnl_link_unregister(&dummy_link_ops);
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700194 rtnl_unlock();
195
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 return err;
Jeff Garzik6aa20a22006-09-13 13:24:59 -0400197}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198
199static void __exit dummy_cleanup_module(void)
200{
Patrick McHardy2d85cba2007-07-11 19:42:13 -0700201 rtnl_link_unregister(&dummy_link_ops);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202}
203
204module_init(dummy_init_module);
205module_exit(dummy_cleanup_module);
206MODULE_LICENSE("GPL");
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700207MODULE_ALIAS_RTNL_LINK("dummy");