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1// SPDX-License-Identifier: GPL-2.0-only
2/* dummy.c: a dummy net driver
3
4 The purpose of this driver is to provide a device to point a
5 route through, but not to actually transmit packets.
6
7 Why? If you have a machine whose only connection is an occasional
8 PPP/SLIP/PLIP link, you can only connect to your own hostname
9 when the link is up. Otherwise you have to use localhost.
10 This isn't very consistent.
11
12 One solution is to set up a dummy link using PPP/SLIP/PLIP,
13 but this seems (to me) too much overhead for too little gain.
14 This driver provides a small alternative. Thus you can do
15
16 [when not running slip]
17 ifconfig dummy slip.addr.ess.here up
18 [to go to slip]
19 ifconfig dummy down
20 dip whatever
21
22 This was written by looking at Donald Becker's skeleton driver
23 and the loopback driver. I then threw away anything that didn't
24 apply! Thanks to Alan Cox for the key clue on what to do with
25 misguided packets.
26
27 Nick Holloway, 27th May 1994
28 [I tweaked this explanation a little but that's all]
29 Alan Cox, 30th May 1994
30*/
31
32#include <linux/module.h>
33#include <linux/kernel.h>
34#include <linux/netdevice.h>
35#include <linux/etherdevice.h>
36#include <linux/ethtool.h>
37#include <linux/init.h>
38#include <linux/moduleparam.h>
39#include <linux/rtnetlink.h>
40#include <linux/net_tstamp.h>
41#include <net/rtnetlink.h>
42#include <linux/u64_stats_sync.h>
43
44#define DRV_NAME "dummy"
45#define DRV_VERSION "1.0"
46
47static int numdummies = 1;
48
49/* fake multicast ability */
50static void set_multicast_list(struct net_device *dev)
51{
52}
53
54struct pcpu_dstats {
55 u64 tx_packets;
56 u64 tx_bytes;
57 struct u64_stats_sync syncp;
58};
59
60static void dummy_get_stats64(struct net_device *dev,
61 struct rtnl_link_stats64 *stats)
62{
63 int i;
64
65 for_each_possible_cpu(i) {
66 const struct pcpu_dstats *dstats;
67 u64 tbytes, tpackets;
68 unsigned int start;
69
70 dstats = per_cpu_ptr(dev->dstats, i);
71 do {
72 start = u64_stats_fetch_begin_irq(&dstats->syncp);
73 tbytes = dstats->tx_bytes;
74 tpackets = dstats->tx_packets;
75 } while (u64_stats_fetch_retry_irq(&dstats->syncp, start));
76 stats->tx_bytes += tbytes;
77 stats->tx_packets += tpackets;
78 }
79}
80
81static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev)
82{
83 struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats);
84
85 u64_stats_update_begin(&dstats->syncp);
86 dstats->tx_packets++;
87 dstats->tx_bytes += skb->len;
88 u64_stats_update_end(&dstats->syncp);
89
90 skb_tx_timestamp(skb);
91 dev_kfree_skb(skb);
92 return NETDEV_TX_OK;
93}
94
95static int dummy_dev_init(struct net_device *dev)
96{
97 dev->dstats = netdev_alloc_pcpu_stats(struct pcpu_dstats);
98 if (!dev->dstats)
99 return -ENOMEM;
100
101 return 0;
102}
103
104static void dummy_dev_uninit(struct net_device *dev)
105{
106 free_percpu(dev->dstats);
107}
108
109static int dummy_change_carrier(struct net_device *dev, bool new_carrier)
110{
111 if (new_carrier)
112 netif_carrier_on(dev);
113 else
114 netif_carrier_off(dev);
115 return 0;
116}
117
118static const struct net_device_ops dummy_netdev_ops = {
119 .ndo_init = dummy_dev_init,
120 .ndo_uninit = dummy_dev_uninit,
121 .ndo_start_xmit = dummy_xmit,
122 .ndo_validate_addr = eth_validate_addr,
123 .ndo_set_rx_mode = set_multicast_list,
124 .ndo_set_mac_address = eth_mac_addr,
125 .ndo_get_stats64 = dummy_get_stats64,
126 .ndo_change_carrier = dummy_change_carrier,
127};
128
129static void dummy_get_drvinfo(struct net_device *dev,
130 struct ethtool_drvinfo *info)
131{
132 strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
133 strlcpy(info->version, DRV_VERSION, sizeof(info->version));
134}
135
136static const struct ethtool_ops dummy_ethtool_ops = {
137 .get_drvinfo = dummy_get_drvinfo,
138 .get_ts_info = ethtool_op_get_ts_info,
139};
140
141static void dummy_setup(struct net_device *dev)
142{
143 ether_setup(dev);
144
145 /* Initialize the device structure. */
146 dev->netdev_ops = &dummy_netdev_ops;
147 dev->ethtool_ops = &dummy_ethtool_ops;
148 dev->needs_free_netdev = true;
149
150 /* Fill in device structure with ethernet-generic values. */
151 dev->flags |= IFF_NOARP;
152 dev->flags &= ~IFF_MULTICAST;
153 dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE;
154 dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST;
155 dev->features |= NETIF_F_ALL_TSO;
156 dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX;
157 dev->features |= NETIF_F_GSO_ENCAP_ALL;
158 dev->hw_features |= dev->features;
159 dev->hw_enc_features |= dev->features;
160 eth_hw_addr_random(dev);
161
162 dev->min_mtu = 0;
163 dev->max_mtu = 0;
164}
165
166static int dummy_validate(struct nlattr *tb[], struct nlattr *data[],
167 struct netlink_ext_ack *extack)
168{
169 if (tb[IFLA_ADDRESS]) {
170 if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
171 return -EINVAL;
172 if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
173 return -EADDRNOTAVAIL;
174 }
175 return 0;
176}
177
178static struct rtnl_link_ops dummy_link_ops __read_mostly = {
179 .kind = DRV_NAME,
180 .setup = dummy_setup,
181 .validate = dummy_validate,
182};
183
184/* Number of dummy devices to be set up by this module. */
185module_param(numdummies, int, 0);
186MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
187
188static int __init dummy_init_one(void)
189{
190 struct net_device *dev_dummy;
191 int err;
192
193 dev_dummy = alloc_netdev(0, "dummy%d", NET_NAME_ENUM, dummy_setup);
194 if (!dev_dummy)
195 return -ENOMEM;
196
197 dev_dummy->rtnl_link_ops = &dummy_link_ops;
198 err = register_netdevice(dev_dummy);
199 if (err < 0)
200 goto err;
201 return 0;
202
203err:
204 free_netdev(dev_dummy);
205 return err;
206}
207
208static int __init dummy_init_module(void)
209{
210 int i, err = 0;
211
212 down_write(&pernet_ops_rwsem);
213 rtnl_lock();
214 err = __rtnl_link_register(&dummy_link_ops);
215 if (err < 0)
216 goto out;
217
218 for (i = 0; i < numdummies && !err; i++) {
219 err = dummy_init_one();
220 cond_resched();
221 }
222 if (err < 0)
223 __rtnl_link_unregister(&dummy_link_ops);
224
225out:
226 rtnl_unlock();
227 up_write(&pernet_ops_rwsem);
228
229 return err;
230}
231
232static void __exit dummy_cleanup_module(void)
233{
234 rtnl_link_unregister(&dummy_link_ops);
235}
236
237module_init(dummy_init_module);
238module_exit(dummy_cleanup_module);
239MODULE_LICENSE("GPL");
240MODULE_ALIAS_RTNL_LINK(DRV_NAME);
241MODULE_VERSION(DRV_VERSION);
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
41#define DRV_NAME "dummy"
42#define DRV_VERSION "1.0"
43
44static int numdummies = 1;
45
46/* fake multicast ability */
47static void set_multicast_list(struct net_device *dev)
48{
49}
50
51struct pcpu_dstats {
52 u64 tx_packets;
53 u64 tx_bytes;
54 struct u64_stats_sync syncp;
55};
56
57static struct rtnl_link_stats64 *dummy_get_stats64(struct net_device *dev,
58 struct rtnl_link_stats64 *stats)
59{
60 int i;
61
62 for_each_possible_cpu(i) {
63 const struct pcpu_dstats *dstats;
64 u64 tbytes, tpackets;
65 unsigned int start;
66
67 dstats = per_cpu_ptr(dev->dstats, i);
68 do {
69 start = u64_stats_fetch_begin_irq(&dstats->syncp);
70 tbytes = dstats->tx_bytes;
71 tpackets = dstats->tx_packets;
72 } while (u64_stats_fetch_retry_irq(&dstats->syncp, start));
73 stats->tx_bytes += tbytes;
74 stats->tx_packets += tpackets;
75 }
76 return stats;
77}
78
79static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev)
80{
81 struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats);
82
83 u64_stats_update_begin(&dstats->syncp);
84 dstats->tx_packets++;
85 dstats->tx_bytes += skb->len;
86 u64_stats_update_end(&dstats->syncp);
87
88 dev_kfree_skb(skb);
89 return NETDEV_TX_OK;
90}
91
92static int dummy_dev_init(struct net_device *dev)
93{
94 dev->dstats = netdev_alloc_pcpu_stats(struct pcpu_dstats);
95 if (!dev->dstats)
96 return -ENOMEM;
97
98 return 0;
99}
100
101static void dummy_dev_uninit(struct net_device *dev)
102{
103 free_percpu(dev->dstats);
104}
105
106static int dummy_change_carrier(struct net_device *dev, bool new_carrier)
107{
108 if (new_carrier)
109 netif_carrier_on(dev);
110 else
111 netif_carrier_off(dev);
112 return 0;
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 = eth_mac_addr,
122 .ndo_get_stats64 = dummy_get_stats64,
123 .ndo_change_carrier = dummy_change_carrier,
124};
125
126static void dummy_get_drvinfo(struct net_device *dev,
127 struct ethtool_drvinfo *info)
128{
129 strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
130 strlcpy(info->version, DRV_VERSION, sizeof(info->version));
131}
132
133static const struct ethtool_ops dummy_ethtool_ops = {
134 .get_drvinfo = dummy_get_drvinfo,
135};
136
137static void dummy_setup(struct net_device *dev)
138{
139 ether_setup(dev);
140
141 /* Initialize the device structure. */
142 dev->netdev_ops = &dummy_netdev_ops;
143 dev->ethtool_ops = &dummy_ethtool_ops;
144 dev->destructor = free_netdev;
145
146 /* Fill in device structure with ethernet-generic values. */
147 dev->flags |= IFF_NOARP;
148 dev->flags &= ~IFF_MULTICAST;
149 dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE;
150 dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST;
151 dev->features |= NETIF_F_ALL_TSO | NETIF_F_UFO;
152 dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX;
153 dev->features |= NETIF_F_GSO_ENCAP_ALL;
154 dev->hw_features |= dev->features;
155 dev->hw_enc_features |= dev->features;
156 eth_hw_addr_random(dev);
157}
158
159static int dummy_validate(struct nlattr *tb[], struct nlattr *data[])
160{
161 if (tb[IFLA_ADDRESS]) {
162 if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
163 return -EINVAL;
164 if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
165 return -EADDRNOTAVAIL;
166 }
167 return 0;
168}
169
170static struct rtnl_link_ops dummy_link_ops __read_mostly = {
171 .kind = DRV_NAME,
172 .setup = dummy_setup,
173 .validate = dummy_validate,
174};
175
176/* Number of dummy devices to be set up by this module. */
177module_param(numdummies, int, 0);
178MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
179
180static int __init dummy_init_one(void)
181{
182 struct net_device *dev_dummy;
183 int err;
184
185 dev_dummy = alloc_netdev(0, "dummy%d", NET_NAME_UNKNOWN, dummy_setup);
186 if (!dev_dummy)
187 return -ENOMEM;
188
189 dev_dummy->rtnl_link_ops = &dummy_link_ops;
190 err = register_netdevice(dev_dummy);
191 if (err < 0)
192 goto err;
193 return 0;
194
195err:
196 free_netdev(dev_dummy);
197 return err;
198}
199
200static int __init dummy_init_module(void)
201{
202 int i, err = 0;
203
204 rtnl_lock();
205 err = __rtnl_link_register(&dummy_link_ops);
206 if (err < 0)
207 goto out;
208
209 for (i = 0; i < numdummies && !err; i++) {
210 err = dummy_init_one();
211 cond_resched();
212 }
213 if (err < 0)
214 __rtnl_link_unregister(&dummy_link_ops);
215
216out:
217 rtnl_unlock();
218
219 return err;
220}
221
222static void __exit dummy_cleanup_module(void)
223{
224 rtnl_link_unregister(&dummy_link_ops);
225}
226
227module_init(dummy_init_module);
228module_exit(dummy_cleanup_module);
229MODULE_LICENSE("GPL");
230MODULE_ALIAS_RTNL_LINK(DRV_NAME);
231MODULE_VERSION(DRV_VERSION);