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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
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 memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN);
51 return 0;
52}
53
54/* fake multicast ability */
55static void set_multicast_list(struct net_device *dev)
56{
57}
58
59struct pcpu_dstats {
60 u64 tx_packets;
61 u64 tx_bytes;
62 struct u64_stats_sync syncp;
63};
64
65static struct rtnl_link_stats64 *dummy_get_stats64(struct net_device *dev,
66 struct rtnl_link_stats64 *stats)
67{
68 int i;
69
70 for_each_possible_cpu(i) {
71 const struct pcpu_dstats *dstats;
72 u64 tbytes, tpackets;
73 unsigned int start;
74
75 dstats = per_cpu_ptr(dev->dstats, i);
76 do {
77 start = u64_stats_fetch_begin(&dstats->syncp);
78 tbytes = dstats->tx_bytes;
79 tpackets = dstats->tx_packets;
80 } while (u64_stats_fetch_retry(&dstats->syncp, start));
81 stats->tx_bytes += tbytes;
82 stats->tx_packets += tpackets;
83 }
84 return stats;
85}
86
87static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev)
88{
89 struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats);
90
91 u64_stats_update_begin(&dstats->syncp);
92 dstats->tx_packets++;
93 dstats->tx_bytes += skb->len;
94 u64_stats_update_end(&dstats->syncp);
95
96 dev_kfree_skb(skb);
97 return NETDEV_TX_OK;
98}
99
100static int dummy_dev_init(struct net_device *dev)
101{
102 dev->dstats = alloc_percpu(struct pcpu_dstats);
103 if (!dev->dstats)
104 return -ENOMEM;
105
106 return 0;
107}
108
109static void dummy_dev_free(struct net_device *dev)
110{
111 free_percpu(dev->dstats);
112 free_netdev(dev);
113}
114
115static const struct net_device_ops dummy_netdev_ops = {
116 .ndo_init = dummy_dev_init,
117 .ndo_start_xmit = dummy_xmit,
118 .ndo_validate_addr = eth_validate_addr,
119 .ndo_set_multicast_list = set_multicast_list,
120 .ndo_set_mac_address = dummy_set_address,
121 .ndo_get_stats64 = dummy_get_stats64,
122};
123
124static void dummy_setup(struct net_device *dev)
125{
126 ether_setup(dev);
127
128 /* Initialize the device structure. */
129 dev->netdev_ops = &dummy_netdev_ops;
130 dev->destructor = dummy_dev_free;
131
132 /* Fill in device structure with ethernet-generic values. */
133 dev->tx_queue_len = 0;
134 dev->flags |= IFF_NOARP;
135 dev->flags &= ~IFF_MULTICAST;
136 dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO;
137 dev->features |= NETIF_F_NO_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX;
138 random_ether_addr(dev->dev_addr);
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
189 for (i = 0; i < numdummies && !err; i++)
190 err = dummy_init_one();
191 if (err < 0)
192 __rtnl_link_unregister(&dummy_link_ops);
193 rtnl_unlock();
194
195 return err;
196}
197
198static void __exit dummy_cleanup_module(void)
199{
200 rtnl_link_unregister(&dummy_link_ops);
201}
202
203module_init(dummy_init_module);
204module_exit(dummy_cleanup_module);
205MODULE_LICENSE("GPL");
206MODULE_ALIAS_RTNL_LINK("dummy");
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);