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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// 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
46static int numdummies = 1;
47
48/* fake multicast ability */
49static void set_multicast_list(struct net_device *dev)
50{
51}
52
53static void dummy_get_stats64(struct net_device *dev,
54 struct rtnl_link_stats64 *stats)
55{
56 dev_lstats_read(dev, &stats->tx_packets, &stats->tx_bytes);
57}
58
59static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev)
60{
61 dev_lstats_add(dev, skb->len);
62
63 skb_tx_timestamp(skb);
64 dev_kfree_skb(skb);
65 return NETDEV_TX_OK;
66}
67
68static int dummy_dev_init(struct net_device *dev)
69{
70 dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
71 if (!dev->lstats)
72 return -ENOMEM;
73
74 return 0;
75}
76
77static void dummy_dev_uninit(struct net_device *dev)
78{
79 free_percpu(dev->lstats);
80}
81
82static int dummy_change_carrier(struct net_device *dev, bool new_carrier)
83{
84 if (new_carrier)
85 netif_carrier_on(dev);
86 else
87 netif_carrier_off(dev);
88 return 0;
89}
90
91static const struct net_device_ops dummy_netdev_ops = {
92 .ndo_init = dummy_dev_init,
93 .ndo_uninit = dummy_dev_uninit,
94 .ndo_start_xmit = dummy_xmit,
95 .ndo_validate_addr = eth_validate_addr,
96 .ndo_set_rx_mode = set_multicast_list,
97 .ndo_set_mac_address = eth_mac_addr,
98 .ndo_get_stats64 = dummy_get_stats64,
99 .ndo_change_carrier = dummy_change_carrier,
100};
101
102static void dummy_get_drvinfo(struct net_device *dev,
103 struct ethtool_drvinfo *info)
104{
105 strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
106}
107
108static const struct ethtool_ops dummy_ethtool_ops = {
109 .get_drvinfo = dummy_get_drvinfo,
110 .get_ts_info = ethtool_op_get_ts_info,
111};
112
113static void dummy_setup(struct net_device *dev)
114{
115 ether_setup(dev);
116
117 /* Initialize the device structure. */
118 dev->netdev_ops = &dummy_netdev_ops;
119 dev->ethtool_ops = &dummy_ethtool_ops;
120 dev->needs_free_netdev = true;
121
122 /* Fill in device structure with ethernet-generic values. */
123 dev->flags |= IFF_NOARP;
124 dev->flags &= ~IFF_MULTICAST;
125 dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE;
126 dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST;
127 dev->features |= NETIF_F_ALL_TSO;
128 dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX;
129 dev->features |= NETIF_F_GSO_ENCAP_ALL;
130 dev->hw_features |= dev->features;
131 dev->hw_enc_features |= dev->features;
132 eth_hw_addr_random(dev);
133
134 dev->min_mtu = 0;
135 dev->max_mtu = 0;
136}
137
138static int dummy_validate(struct nlattr *tb[], struct nlattr *data[],
139 struct netlink_ext_ack *extack)
140{
141 if (tb[IFLA_ADDRESS]) {
142 if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
143 return -EINVAL;
144 if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
145 return -EADDRNOTAVAIL;
146 }
147 return 0;
148}
149
150static struct rtnl_link_ops dummy_link_ops __read_mostly = {
151 .kind = DRV_NAME,
152 .setup = dummy_setup,
153 .validate = dummy_validate,
154};
155
156/* Number of dummy devices to be set up by this module. */
157module_param(numdummies, int, 0);
158MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
159
160static int __init dummy_init_one(void)
161{
162 struct net_device *dev_dummy;
163 int err;
164
165 dev_dummy = alloc_netdev(0, "dummy%d", NET_NAME_ENUM, dummy_setup);
166 if (!dev_dummy)
167 return -ENOMEM;
168
169 dev_dummy->rtnl_link_ops = &dummy_link_ops;
170 err = register_netdevice(dev_dummy);
171 if (err < 0)
172 goto err;
173 return 0;
174
175err:
176 free_netdev(dev_dummy);
177 return err;
178}
179
180static int __init dummy_init_module(void)
181{
182 int i, err = 0;
183
184 down_write(&pernet_ops_rwsem);
185 rtnl_lock();
186 err = __rtnl_link_register(&dummy_link_ops);
187 if (err < 0)
188 goto out;
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
197out:
198 rtnl_unlock();
199 up_write(&pernet_ops_rwsem);
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(DRV_NAME);