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1/* 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
14
15 [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
31#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>
37#include <linux/rtnetlink.h>
38#include <net/rtnetlink.h>
39#include <linux/u64_stats_sync.h>
40
41static int numdummies = 1;
42
43/* fake multicast ability */
44static void set_multicast_list(struct net_device *dev)
45{
46}
47
48struct pcpu_dstats {
49 u64 tx_packets;
50 u64 tx_bytes;
51 struct u64_stats_sync syncp;
52};
53
54static struct rtnl_link_stats64 *dummy_get_stats64(struct net_device *dev,
55 struct rtnl_link_stats64 *stats)
56{
57 int i;
58
59 for_each_possible_cpu(i) {
60 const struct pcpu_dstats *dstats;
61 u64 tbytes, tpackets;
62 unsigned int start;
63
64 dstats = per_cpu_ptr(dev->dstats, i);
65 do {
66 start = u64_stats_fetch_begin_irq(&dstats->syncp);
67 tbytes = dstats->tx_bytes;
68 tpackets = dstats->tx_packets;
69 } while (u64_stats_fetch_retry_irq(&dstats->syncp, start));
70 stats->tx_bytes += tbytes;
71 stats->tx_packets += tpackets;
72 }
73 return stats;
74}
75
76static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev)
77{
78 struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats);
79
80 u64_stats_update_begin(&dstats->syncp);
81 dstats->tx_packets++;
82 dstats->tx_bytes += skb->len;
83 u64_stats_update_end(&dstats->syncp);
84
85 dev_kfree_skb(skb);
86 return NETDEV_TX_OK;
87}
88
89static int dummy_dev_init(struct net_device *dev)
90{
91 dev->dstats = netdev_alloc_pcpu_stats(struct pcpu_dstats);
92 if (!dev->dstats)
93 return -ENOMEM;
94
95 return 0;
96}
97
98static void dummy_dev_uninit(struct net_device *dev)
99{
100 free_percpu(dev->dstats);
101}
102
103static int dummy_change_carrier(struct net_device *dev, bool new_carrier)
104{
105 if (new_carrier)
106 netif_carrier_on(dev);
107 else
108 netif_carrier_off(dev);
109 return 0;
110}
111
112static const struct net_device_ops dummy_netdev_ops = {
113 .ndo_init = dummy_dev_init,
114 .ndo_uninit = dummy_dev_uninit,
115 .ndo_start_xmit = dummy_xmit,
116 .ndo_validate_addr = eth_validate_addr,
117 .ndo_set_rx_mode = set_multicast_list,
118 .ndo_set_mac_address = eth_mac_addr,
119 .ndo_get_stats64 = dummy_get_stats64,
120 .ndo_change_carrier = dummy_change_carrier,
121};
122
123static void dummy_setup(struct net_device *dev)
124{
125 ether_setup(dev);
126
127 /* Initialize the device structure. */
128 dev->netdev_ops = &dummy_netdev_ops;
129 dev->destructor = free_netdev;
130
131 /* Fill in device structure with ethernet-generic values. */
132 dev->tx_queue_len = 0;
133 dev->flags |= IFF_NOARP;
134 dev->flags &= ~IFF_MULTICAST;
135 dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
136 dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO;
137 dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX;
138 eth_hw_addr_random(dev);
139}
140
141static int dummy_validate(struct nlattr *tb[], struct nlattr *data[])
142{
143 if (tb[IFLA_ADDRESS]) {
144 if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
145 return -EINVAL;
146 if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
147 return -EADDRNOTAVAIL;
148 }
149 return 0;
150}
151
152static struct rtnl_link_ops dummy_link_ops __read_mostly = {
153 .kind = "dummy",
154 .setup = dummy_setup,
155 .validate = dummy_validate,
156};
157
158/* Number of dummy devices to be set up by this module. */
159module_param(numdummies, int, 0);
160MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
161
162static int __init dummy_init_one(void)
163{
164 struct net_device *dev_dummy;
165 int err;
166
167 dev_dummy = alloc_netdev(0, "dummy%d", dummy_setup);
168 if (!dev_dummy)
169 return -ENOMEM;
170
171 dev_dummy->rtnl_link_ops = &dummy_link_ops;
172 err = register_netdevice(dev_dummy);
173 if (err < 0)
174 goto err;
175 return 0;
176
177err:
178 free_netdev(dev_dummy);
179 return err;
180}
181
182static int __init dummy_init_module(void)
183{
184 int i, err = 0;
185
186 rtnl_lock();
187 err = __rtnl_link_register(&dummy_link_ops);
188 if (err < 0)
189 goto out;
190
191 for (i = 0; i < numdummies && !err; i++) {
192 err = dummy_init_one();
193 cond_resched();
194 }
195 if (err < 0)
196 __rtnl_link_unregister(&dummy_link_ops);
197
198out:
199 rtnl_unlock();
200
201 return err;
202}
203
204static void __exit dummy_cleanup_module(void)
205{
206 rtnl_link_unregister(&dummy_link_ops);
207}
208
209module_init(dummy_init_module);
210module_exit(dummy_cleanup_module);
211MODULE_LICENSE("GPL");
212MODULE_ALIAS_RTNL_LINK("dummy");
1/* 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
14
15 [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
31#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>
37#include <linux/rtnetlink.h>
38#include <net/rtnetlink.h>
39#include <linux/u64_stats_sync.h>
40
41static int numdummies = 1;
42
43static int dummy_set_address(struct net_device *dev, void *p)
44{
45 struct sockaddr *sa = p;
46
47 if (!is_valid_ether_addr(sa->sa_data))
48 return -EADDRNOTAVAIL;
49
50 dev->addr_assign_type &= ~NET_ADDR_RANDOM;
51 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
60struct 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}
87
88static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev)
89{
90 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);
96
97 dev_kfree_skb(skb);
98 return NETDEV_TX_OK;
99}
100
101static 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
110static void dummy_dev_uninit(struct net_device *dev)
111{
112 free_percpu(dev->dstats);
113}
114
115static const struct net_device_ops dummy_netdev_ops = {
116 .ndo_init = dummy_dev_init,
117 .ndo_uninit = dummy_dev_uninit,
118 .ndo_start_xmit = dummy_xmit,
119 .ndo_validate_addr = eth_validate_addr,
120 .ndo_set_rx_mode = set_multicast_list,
121 .ndo_set_mac_address = dummy_set_address,
122 .ndo_get_stats64 = dummy_get_stats64,
123};
124
125static void dummy_setup(struct net_device *dev)
126{
127 ether_setup(dev);
128
129 /* Initialize the device structure. */
130 dev->netdev_ops = &dummy_netdev_ops;
131 dev->destructor = free_netdev;
132
133 /* Fill in device structure with ethernet-generic values. */
134 dev->tx_queue_len = 0;
135 dev->flags |= IFF_NOARP;
136 dev->flags &= ~IFF_MULTICAST;
137 dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO;
138 dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX;
139 eth_hw_addr_random(dev);
140}
141
142static 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
153static struct rtnl_link_ops dummy_link_ops __read_mostly = {
154 .kind = "dummy",
155 .setup = dummy_setup,
156 .validate = dummy_validate,
157};
158
159/* 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
163static int __init dummy_init_one(void)
164{
165 struct net_device *dev_dummy;
166 int err;
167
168 dev_dummy = alloc_netdev(0, "dummy%d", dummy_setup);
169 if (!dev_dummy)
170 return -ENOMEM;
171
172 dev_dummy->rtnl_link_ops = &dummy_link_ops;
173 err = register_netdevice(dev_dummy);
174 if (err < 0)
175 goto err;
176 return 0;
177
178err:
179 free_netdev(dev_dummy);
180 return err;
181}
182
183static int __init dummy_init_module(void)
184{
185 int i, err = 0;
186
187 rtnl_lock();
188 err = __rtnl_link_register(&dummy_link_ops);
189
190 for (i = 0; i < numdummies && !err; i++) {
191 err = dummy_init_one();
192 cond_resched();
193 }
194 if (err < 0)
195 __rtnl_link_unregister(&dummy_link_ops);
196 rtnl_unlock();
197
198 return err;
199}
200
201static void __exit dummy_cleanup_module(void)
202{
203 rtnl_link_unregister(&dummy_link_ops);
204}
205
206module_init(dummy_init_module);
207module_exit(dummy_cleanup_module);
208MODULE_LICENSE("GPL");
209MODULE_ALIAS_RTNL_LINK("dummy");