Commit | Line | Data |
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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 | 44 | #define DRV_NAME "dummy" |
c19be735 | 45 | |
1da177e4 LT |
46 | static int numdummies = 1; |
47 | ||
1da177e4 LT |
48 | /* fake multicast ability */ |
49 | static void set_multicast_list(struct net_device *dev) | |
50 | { | |
51 | } | |
52 | ||
bc1f4470 | 53 | static void dummy_get_stats64(struct net_device *dev, |
54 | struct rtnl_link_stats64 *stats) | |
6d81f41c | 55 | { |
4a43b1f9 | 56 | dev_lstats_read(dev, &stats->tx_packets, &stats->tx_bytes); |
6d81f41c | 57 | } |
424efe9c SH |
58 | |
59 | static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev) | |
60 | { | |
4a43b1f9 | 61 | dev_lstats_add(dev, skb->len); |
424efe9c | 62 | |
6df014cf | 63 | skb_tx_timestamp(skb); |
424efe9c SH |
64 | dev_kfree_skb(skb); |
65 | return NETDEV_TX_OK; | |
66 | } | |
67 | ||
6d81f41c ED |
68 | static int dummy_dev_init(struct net_device *dev) |
69 | { | |
a381690d | 70 | dev->pcpu_stat_type = NETDEV_PCPU_STAT_LSTATS; |
6d81f41c | 71 | |
0bef5120 | 72 | netdev_lockdep_set_classes(dev); |
6d81f41c ED |
73 | return 0; |
74 | } | |
75 | ||
210ab665 JP |
76 | static int dummy_change_carrier(struct net_device *dev, bool new_carrier) |
77 | { | |
78 | if (new_carrier) | |
79 | netif_carrier_on(dev); | |
80 | else | |
81 | netif_carrier_off(dev); | |
82 | return 0; | |
83 | } | |
84 | ||
aa18e9e8 | 85 | static const struct net_device_ops dummy_netdev_ops = { |
6d81f41c | 86 | .ndo_init = dummy_dev_init, |
aa18e9e8 SH |
87 | .ndo_start_xmit = dummy_xmit, |
88 | .ndo_validate_addr = eth_validate_addr, | |
afc4b13d | 89 | .ndo_set_rx_mode = set_multicast_list, |
0d1632b4 | 90 | .ndo_set_mac_address = eth_mac_addr, |
6d81f41c | 91 | .ndo_get_stats64 = dummy_get_stats64, |
210ab665 | 92 | .ndo_change_carrier = dummy_change_carrier, |
aa18e9e8 SH |
93 | }; |
94 | ||
c19be735 | 95 | static const struct ethtool_ops dummy_ethtool_ops = { |
abe9fd57 | 96 | .get_ts_info = ethtool_op_get_ts_info, |
c19be735 FL |
97 | }; |
98 | ||
5d5cb173 | 99 | static void dummy_setup(struct net_device *dev) |
1da177e4 | 100 | { |
aa18e9e8 SH |
101 | ether_setup(dev); |
102 | ||
1da177e4 | 103 | /* Initialize the device structure. */ |
aa18e9e8 | 104 | dev->netdev_ops = &dummy_netdev_ops; |
c19be735 | 105 | dev->ethtool_ops = &dummy_ethtool_ops; |
cf124db5 | 106 | dev->needs_free_netdev = true; |
1da177e4 LT |
107 | |
108 | /* Fill in device structure with ethernet-generic values. */ | |
1da177e4 LT |
109 | dev->flags |= IFF_NOARP; |
110 | dev->flags &= ~IFF_MULTICAST; | |
ff42c02c | 111 | dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE; |
8f3af277 | 112 | dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST; |
ecb8fed4 | 113 | dev->features |= NETIF_F_GSO_SOFTWARE; |
34324dc2 | 114 | dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX; |
8f3af277 ED |
115 | dev->features |= NETIF_F_GSO_ENCAP_ALL; |
116 | dev->hw_features |= dev->features; | |
117 | dev->hw_enc_features |= dev->features; | |
7ce5d222 | 118 | eth_hw_addr_random(dev); |
25e3e84b ZS |
119 | |
120 | dev->min_mtu = 0; | |
e94cd811 | 121 | dev->max_mtu = 0; |
1da177e4 | 122 | } |
6d81f41c | 123 | |
a8b8a889 MS |
124 | static int dummy_validate(struct nlattr *tb[], struct nlattr *data[], |
125 | struct netlink_ext_ack *extack) | |
0e06877c PM |
126 | { |
127 | if (tb[IFLA_ADDRESS]) { | |
128 | if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN) | |
129 | return -EINVAL; | |
130 | if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS]))) | |
131 | return -EADDRNOTAVAIL; | |
132 | } | |
133 | return 0; | |
134 | } | |
135 | ||
5d5cb173 | 136 | static struct rtnl_link_ops dummy_link_ops __read_mostly = { |
c19be735 | 137 | .kind = DRV_NAME, |
5d5cb173 | 138 | .setup = dummy_setup, |
0e06877c | 139 | .validate = dummy_validate, |
5d5cb173 PM |
140 | }; |
141 | ||
1da177e4 LT |
142 | /* Number of dummy devices to be set up by this module. */ |
143 | module_param(numdummies, int, 0); | |
144 | MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices"); | |
145 | ||
206c9fb2 | 146 | static int __init dummy_init_one(void) |
1da177e4 LT |
147 | { |
148 | struct net_device *dev_dummy; | |
149 | int err; | |
150 | ||
c3361610 | 151 | dev_dummy = alloc_netdev(0, "dummy%d", NET_NAME_ENUM, dummy_setup); |
1da177e4 LT |
152 | if (!dev_dummy) |
153 | return -ENOMEM; | |
154 | ||
5d5cb173 PM |
155 | dev_dummy->rtnl_link_ops = &dummy_link_ops; |
156 | err = register_netdevice(dev_dummy); | |
157 | if (err < 0) | |
158 | goto err; | |
5d5cb173 | 159 | return 0; |
206c9fb2 | 160 | |
5d5cb173 PM |
161 | err: |
162 | free_netdev(dev_dummy); | |
163 | return err; | |
6aa20a22 | 164 | } |
1da177e4 LT |
165 | |
166 | static int __init dummy_init_module(void) | |
6aa20a22 | 167 | { |
1da177e4 | 168 | int i, err = 0; |
206c9fb2 | 169 | |
554873e5 | 170 | down_write(&pernet_ops_rwsem); |
5d5cb173 PM |
171 | rtnl_lock(); |
172 | err = __rtnl_link_register(&dummy_link_ops); | |
2c8a0189 | 173 | if (err < 0) |
174 | goto out; | |
5d5cb173 | 175 | |
16b0dc29 | 176 | for (i = 0; i < numdummies && !err; i++) { |
206c9fb2 | 177 | err = dummy_init_one(); |
16b0dc29 ED |
178 | cond_resched(); |
179 | } | |
2d85cba2 | 180 | if (err < 0) |
5d5cb173 | 181 | __rtnl_link_unregister(&dummy_link_ops); |
2c8a0189 | 182 | |
183 | out: | |
5d5cb173 | 184 | rtnl_unlock(); |
554873e5 | 185 | up_write(&pernet_ops_rwsem); |
5d5cb173 | 186 | |
1da177e4 | 187 | return err; |
6aa20a22 | 188 | } |
1da177e4 LT |
189 | |
190 | static void __exit dummy_cleanup_module(void) | |
191 | { | |
2d85cba2 | 192 | rtnl_link_unregister(&dummy_link_ops); |
1da177e4 LT |
193 | } |
194 | ||
195 | module_init(dummy_init_module); | |
196 | module_exit(dummy_cleanup_module); | |
197 | MODULE_LICENSE("GPL"); | |
55c90047 | 198 | MODULE_DESCRIPTION("Dummy netdevice driver which discards all packets sent to it"); |
c19be735 | 199 | MODULE_ALIAS_RTNL_LINK(DRV_NAME); |