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09c434b8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
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 | |
6aa20a22 | 15 | |
1da177e4 LT |
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 | ||
1da177e4 LT |
32 | #include <linux/module.h> |
33 | #include <linux/kernel.h> | |
34 | #include <linux/netdevice.h> | |
35 | #include <linux/etherdevice.h> | |
abe9fd57 | 36 | #include <linux/ethtool.h> |
1da177e4 LT |
37 | #include <linux/init.h> |
38 | #include <linux/moduleparam.h> | |
206c9fb2 | 39 | #include <linux/rtnetlink.h> |
6df014cf | 40 | #include <linux/net_tstamp.h> |
5d5cb173 | 41 | #include <net/rtnetlink.h> |
6d81f41c | 42 | #include <linux/u64_stats_sync.h> |
206c9fb2 | 43 | |
c19be735 FL |
44 | #define DRV_NAME "dummy" |
45 | #define DRV_VERSION "1.0" | |
46 | ||
1da177e4 LT |
47 | static int numdummies = 1; |
48 | ||
1da177e4 LT |
49 | /* fake multicast ability */ |
50 | static void set_multicast_list(struct net_device *dev) | |
51 | { | |
52 | } | |
53 | ||
6d81f41c ED |
54 | struct pcpu_dstats { |
55 | u64 tx_packets; | |
56 | u64 tx_bytes; | |
57 | struct u64_stats_sync syncp; | |
58 | }; | |
59 | ||
bc1f4470 | 60 | static void dummy_get_stats64(struct net_device *dev, |
61 | struct rtnl_link_stats64 *stats) | |
6d81f41c ED |
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 { | |
57a7744e | 72 | start = u64_stats_fetch_begin_irq(&dstats->syncp); |
6d81f41c ED |
73 | tbytes = dstats->tx_bytes; |
74 | tpackets = dstats->tx_packets; | |
57a7744e | 75 | } while (u64_stats_fetch_retry_irq(&dstats->syncp, start)); |
6d81f41c ED |
76 | stats->tx_bytes += tbytes; |
77 | stats->tx_packets += tpackets; | |
78 | } | |
6d81f41c | 79 | } |
424efe9c SH |
80 | |
81 | static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev) | |
82 | { | |
6d81f41c ED |
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); | |
424efe9c | 89 | |
6df014cf | 90 | skb_tx_timestamp(skb); |
424efe9c SH |
91 | dev_kfree_skb(skb); |
92 | return NETDEV_TX_OK; | |
93 | } | |
94 | ||
6d81f41c ED |
95 | static int dummy_dev_init(struct net_device *dev) |
96 | { | |
1c213bd2 | 97 | dev->dstats = netdev_alloc_pcpu_stats(struct pcpu_dstats); |
6d81f41c ED |
98 | if (!dev->dstats) |
99 | return -ENOMEM; | |
100 | ||
101 | return 0; | |
102 | } | |
103 | ||
890fdf2a | 104 | static void dummy_dev_uninit(struct net_device *dev) |
6d81f41c ED |
105 | { |
106 | free_percpu(dev->dstats); | |
6d81f41c ED |
107 | } |
108 | ||
210ab665 JP |
109 | static 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 | ||
aa18e9e8 | 118 | static const struct net_device_ops dummy_netdev_ops = { |
6d81f41c | 119 | .ndo_init = dummy_dev_init, |
890fdf2a | 120 | .ndo_uninit = dummy_dev_uninit, |
aa18e9e8 SH |
121 | .ndo_start_xmit = dummy_xmit, |
122 | .ndo_validate_addr = eth_validate_addr, | |
afc4b13d | 123 | .ndo_set_rx_mode = set_multicast_list, |
0d1632b4 | 124 | .ndo_set_mac_address = eth_mac_addr, |
6d81f41c | 125 | .ndo_get_stats64 = dummy_get_stats64, |
210ab665 | 126 | .ndo_change_carrier = dummy_change_carrier, |
aa18e9e8 SH |
127 | }; |
128 | ||
c19be735 FL |
129 | static 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 | ||
136 | static const struct ethtool_ops dummy_ethtool_ops = { | |
137 | .get_drvinfo = dummy_get_drvinfo, | |
abe9fd57 | 138 | .get_ts_info = ethtool_op_get_ts_info, |
c19be735 FL |
139 | }; |
140 | ||
5d5cb173 | 141 | static void dummy_setup(struct net_device *dev) |
1da177e4 | 142 | { |
aa18e9e8 SH |
143 | ether_setup(dev); |
144 | ||
1da177e4 | 145 | /* Initialize the device structure. */ |
aa18e9e8 | 146 | dev->netdev_ops = &dummy_netdev_ops; |
c19be735 | 147 | dev->ethtool_ops = &dummy_ethtool_ops; |
cf124db5 | 148 | dev->needs_free_netdev = true; |
1da177e4 LT |
149 | |
150 | /* Fill in device structure with ethernet-generic values. */ | |
1da177e4 LT |
151 | dev->flags |= IFF_NOARP; |
152 | dev->flags &= ~IFF_MULTICAST; | |
ff42c02c | 153 | dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE; |
8f3af277 | 154 | dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST; |
2082499a | 155 | dev->features |= NETIF_F_ALL_TSO; |
34324dc2 | 156 | dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX; |
8f3af277 ED |
157 | dev->features |= NETIF_F_GSO_ENCAP_ALL; |
158 | dev->hw_features |= dev->features; | |
159 | dev->hw_enc_features |= dev->features; | |
7ce5d222 | 160 | eth_hw_addr_random(dev); |
25e3e84b ZS |
161 | |
162 | dev->min_mtu = 0; | |
e94cd811 | 163 | dev->max_mtu = 0; |
1da177e4 | 164 | } |
6d81f41c | 165 | |
a8b8a889 MS |
166 | static int dummy_validate(struct nlattr *tb[], struct nlattr *data[], |
167 | struct netlink_ext_ack *extack) | |
0e06877c PM |
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 | ||
5d5cb173 | 178 | static struct rtnl_link_ops dummy_link_ops __read_mostly = { |
c19be735 | 179 | .kind = DRV_NAME, |
5d5cb173 | 180 | .setup = dummy_setup, |
0e06877c | 181 | .validate = dummy_validate, |
5d5cb173 PM |
182 | }; |
183 | ||
1da177e4 LT |
184 | /* Number of dummy devices to be set up by this module. */ |
185 | module_param(numdummies, int, 0); | |
186 | MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices"); | |
187 | ||
206c9fb2 | 188 | static int __init dummy_init_one(void) |
1da177e4 LT |
189 | { |
190 | struct net_device *dev_dummy; | |
191 | int err; | |
192 | ||
c3361610 | 193 | dev_dummy = alloc_netdev(0, "dummy%d", NET_NAME_ENUM, dummy_setup); |
1da177e4 LT |
194 | if (!dev_dummy) |
195 | return -ENOMEM; | |
196 | ||
5d5cb173 PM |
197 | dev_dummy->rtnl_link_ops = &dummy_link_ops; |
198 | err = register_netdevice(dev_dummy); | |
199 | if (err < 0) | |
200 | goto err; | |
5d5cb173 | 201 | return 0; |
206c9fb2 | 202 | |
5d5cb173 PM |
203 | err: |
204 | free_netdev(dev_dummy); | |
205 | return err; | |
6aa20a22 | 206 | } |
1da177e4 LT |
207 | |
208 | static int __init dummy_init_module(void) | |
6aa20a22 | 209 | { |
1da177e4 | 210 | int i, err = 0; |
206c9fb2 | 211 | |
554873e5 | 212 | down_write(&pernet_ops_rwsem); |
5d5cb173 PM |
213 | rtnl_lock(); |
214 | err = __rtnl_link_register(&dummy_link_ops); | |
2c8a0189 | 215 | if (err < 0) |
216 | goto out; | |
5d5cb173 | 217 | |
16b0dc29 | 218 | for (i = 0; i < numdummies && !err; i++) { |
206c9fb2 | 219 | err = dummy_init_one(); |
16b0dc29 ED |
220 | cond_resched(); |
221 | } | |
2d85cba2 | 222 | if (err < 0) |
5d5cb173 | 223 | __rtnl_link_unregister(&dummy_link_ops); |
2c8a0189 | 224 | |
225 | out: | |
5d5cb173 | 226 | rtnl_unlock(); |
554873e5 | 227 | up_write(&pernet_ops_rwsem); |
5d5cb173 | 228 | |
1da177e4 | 229 | return err; |
6aa20a22 | 230 | } |
1da177e4 LT |
231 | |
232 | static void __exit dummy_cleanup_module(void) | |
233 | { | |
2d85cba2 | 234 | rtnl_link_unregister(&dummy_link_ops); |
1da177e4 LT |
235 | } |
236 | ||
237 | module_init(dummy_init_module); | |
238 | module_exit(dummy_cleanup_module); | |
239 | MODULE_LICENSE("GPL"); | |
c19be735 | 240 | MODULE_ALIAS_RTNL_LINK(DRV_NAME); |
6c702fab | 241 | MODULE_VERSION(DRV_VERSION); |