Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 |
Jeff Garzik | 6aa20a2 | 2006-09-13 13:24:59 -0400 | [diff] [blame] | 14 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
Patrick McHardy | 206c9fb | 2007-06-13 12:04:20 -0700 | [diff] [blame] | 37 | #include <linux/rtnetlink.h> |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 38 | #include <net/rtnetlink.h> |
Eric Dumazet | 6d81f41 | 2010-09-27 20:50:33 +0000 | [diff] [blame] | 39 | #include <linux/u64_stats_sync.h> |
Patrick McHardy | 206c9fb | 2007-06-13 12:04:20 -0700 | [diff] [blame] | 40 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | static int numdummies = 1; |
| 42 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | static int dummy_set_address(struct net_device *dev, void *p) |
| 44 | { |
| 45 | struct sockaddr *sa = p; |
| 46 | |
Jeff Garzik | 6aa20a2 | 2006-09-13 13:24:59 -0400 | [diff] [blame] | 47 | if (!is_valid_ether_addr(sa->sa_data)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | return -EADDRNOTAVAIL; |
Jeff Garzik | 6aa20a2 | 2006-09-13 13:24:59 -0400 | [diff] [blame] | 49 | |
Danny Kukawka | 7ce5d22 | 2012-02-15 06:45:40 +0000 | [diff] [blame] | 50 | dev->addr_assign_type &= ~NET_ADDR_RANDOM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 51 | memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN); |
| 52 | return 0; |
| 53 | } |
| 54 | |
| 55 | /* fake multicast ability */ |
| 56 | static void set_multicast_list(struct net_device *dev) |
| 57 | { |
| 58 | } |
| 59 | |
Eric Dumazet | 6d81f41 | 2010-09-27 20:50:33 +0000 | [diff] [blame] | 60 | struct pcpu_dstats { |
| 61 | u64 tx_packets; |
| 62 | u64 tx_bytes; |
| 63 | struct u64_stats_sync syncp; |
| 64 | }; |
| 65 | |
| 66 | static struct rtnl_link_stats64 *dummy_get_stats64(struct net_device *dev, |
| 67 | struct rtnl_link_stats64 *stats) |
| 68 | { |
| 69 | int i; |
| 70 | |
| 71 | for_each_possible_cpu(i) { |
| 72 | const struct pcpu_dstats *dstats; |
| 73 | u64 tbytes, tpackets; |
| 74 | unsigned int start; |
| 75 | |
| 76 | dstats = per_cpu_ptr(dev->dstats, i); |
| 77 | do { |
| 78 | start = u64_stats_fetch_begin(&dstats->syncp); |
| 79 | tbytes = dstats->tx_bytes; |
| 80 | tpackets = dstats->tx_packets; |
| 81 | } while (u64_stats_fetch_retry(&dstats->syncp, start)); |
| 82 | stats->tx_bytes += tbytes; |
| 83 | stats->tx_packets += tpackets; |
| 84 | } |
| 85 | return stats; |
| 86 | } |
Stephen Hemminger | 424efe9 | 2009-08-31 19:50:51 +0000 | [diff] [blame] | 87 | |
| 88 | static netdev_tx_t dummy_xmit(struct sk_buff *skb, struct net_device *dev) |
| 89 | { |
Eric Dumazet | 6d81f41 | 2010-09-27 20:50:33 +0000 | [diff] [blame] | 90 | struct pcpu_dstats *dstats = this_cpu_ptr(dev->dstats); |
| 91 | |
| 92 | u64_stats_update_begin(&dstats->syncp); |
| 93 | dstats->tx_packets++; |
| 94 | dstats->tx_bytes += skb->len; |
| 95 | u64_stats_update_end(&dstats->syncp); |
Stephen Hemminger | 424efe9 | 2009-08-31 19:50:51 +0000 | [diff] [blame] | 96 | |
| 97 | dev_kfree_skb(skb); |
| 98 | return NETDEV_TX_OK; |
| 99 | } |
| 100 | |
Eric Dumazet | 6d81f41 | 2010-09-27 20:50:33 +0000 | [diff] [blame] | 101 | static int dummy_dev_init(struct net_device *dev) |
| 102 | { |
| 103 | dev->dstats = alloc_percpu(struct pcpu_dstats); |
| 104 | if (!dev->dstats) |
| 105 | return -ENOMEM; |
| 106 | |
| 107 | return 0; |
| 108 | } |
| 109 | |
Hiroaki SHIMODA | 890fdf2 | 2012-04-15 13:26:01 +0000 | [diff] [blame] | 110 | static void dummy_dev_uninit(struct net_device *dev) |
Eric Dumazet | 6d81f41 | 2010-09-27 20:50:33 +0000 | [diff] [blame] | 111 | { |
| 112 | free_percpu(dev->dstats); |
Eric Dumazet | 6d81f41 | 2010-09-27 20:50:33 +0000 | [diff] [blame] | 113 | } |
| 114 | |
Stephen Hemminger | aa18e9e | 2008-11-20 20:28:00 -0800 | [diff] [blame] | 115 | static const struct net_device_ops dummy_netdev_ops = { |
Eric Dumazet | 6d81f41 | 2010-09-27 20:50:33 +0000 | [diff] [blame] | 116 | .ndo_init = dummy_dev_init, |
Hiroaki SHIMODA | 890fdf2 | 2012-04-15 13:26:01 +0000 | [diff] [blame] | 117 | .ndo_uninit = dummy_dev_uninit, |
Stephen Hemminger | aa18e9e | 2008-11-20 20:28:00 -0800 | [diff] [blame] | 118 | .ndo_start_xmit = dummy_xmit, |
| 119 | .ndo_validate_addr = eth_validate_addr, |
Jiri Pirko | afc4b13 | 2011-08-16 06:29:01 +0000 | [diff] [blame] | 120 | .ndo_set_rx_mode = set_multicast_list, |
Stephen Hemminger | aa18e9e | 2008-11-20 20:28:00 -0800 | [diff] [blame] | 121 | .ndo_set_mac_address = dummy_set_address, |
Eric Dumazet | 6d81f41 | 2010-09-27 20:50:33 +0000 | [diff] [blame] | 122 | .ndo_get_stats64 = dummy_get_stats64, |
Stephen Hemminger | aa18e9e | 2008-11-20 20:28:00 -0800 | [diff] [blame] | 123 | }; |
| 124 | |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 125 | static void dummy_setup(struct net_device *dev) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 126 | { |
Stephen Hemminger | aa18e9e | 2008-11-20 20:28:00 -0800 | [diff] [blame] | 127 | ether_setup(dev); |
| 128 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | /* Initialize the device structure. */ |
Stephen Hemminger | aa18e9e | 2008-11-20 20:28:00 -0800 | [diff] [blame] | 130 | dev->netdev_ops = &dummy_netdev_ops; |
Hiroaki SHIMODA | 890fdf2 | 2012-04-15 13:26:01 +0000 | [diff] [blame] | 131 | dev->destructor = free_netdev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 132 | |
| 133 | /* Fill in device structure with ethernet-generic values. */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | dev->tx_queue_len = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 135 | dev->flags |= IFF_NOARP; |
| 136 | dev->flags &= ~IFF_MULTICAST; |
Eric Dumazet | 6d81f41 | 2010-09-27 20:50:33 +0000 | [diff] [blame] | 137 | dev->features |= NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO; |
Michał Mirosław | 34324dc | 2011-11-15 15:29:55 +0000 | [diff] [blame] | 138 | dev->features |= NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_LLTX; |
Danny Kukawka | 7ce5d22 | 2012-02-15 06:45:40 +0000 | [diff] [blame] | 139 | eth_hw_addr_random(dev); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | } |
Eric Dumazet | 6d81f41 | 2010-09-27 20:50:33 +0000 | [diff] [blame] | 141 | |
Patrick McHardy | 0e06877 | 2007-07-11 19:42:31 -0700 | [diff] [blame] | 142 | static int dummy_validate(struct nlattr *tb[], struct nlattr *data[]) |
| 143 | { |
| 144 | if (tb[IFLA_ADDRESS]) { |
| 145 | if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN) |
| 146 | return -EINVAL; |
| 147 | if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS]))) |
| 148 | return -EADDRNOTAVAIL; |
| 149 | } |
| 150 | return 0; |
| 151 | } |
| 152 | |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 153 | static struct rtnl_link_ops dummy_link_ops __read_mostly = { |
| 154 | .kind = "dummy", |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 155 | .setup = dummy_setup, |
Patrick McHardy | 0e06877 | 2007-07-11 19:42:31 -0700 | [diff] [blame] | 156 | .validate = dummy_validate, |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 157 | }; |
| 158 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 159 | /* Number of dummy devices to be set up by this module. */ |
| 160 | module_param(numdummies, int, 0); |
| 161 | MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices"); |
| 162 | |
Patrick McHardy | 206c9fb | 2007-06-13 12:04:20 -0700 | [diff] [blame] | 163 | static int __init dummy_init_one(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 164 | { |
| 165 | struct net_device *dev_dummy; |
| 166 | int err; |
| 167 | |
Patrick McHardy | 2d85cba | 2007-07-11 19:42:13 -0700 | [diff] [blame] | 168 | dev_dummy = alloc_netdev(0, "dummy%d", dummy_setup); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 169 | if (!dev_dummy) |
| 170 | return -ENOMEM; |
| 171 | |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 172 | dev_dummy->rtnl_link_ops = &dummy_link_ops; |
| 173 | err = register_netdevice(dev_dummy); |
| 174 | if (err < 0) |
| 175 | goto err; |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 176 | return 0; |
| 177 | |
| 178 | err: |
| 179 | free_netdev(dev_dummy); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 180 | return err; |
| 181 | } |
| 182 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 183 | static int __init dummy_init_module(void) |
Jeff Garzik | 6aa20a2 | 2006-09-13 13:24:59 -0400 | [diff] [blame] | 184 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 185 | int i, err = 0; |
Patrick McHardy | 206c9fb | 2007-06-13 12:04:20 -0700 | [diff] [blame] | 186 | |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 187 | rtnl_lock(); |
| 188 | err = __rtnl_link_register(&dummy_link_ops); |
| 189 | |
Eric Dumazet | 16b0dc2 | 2012-06-10 21:11:57 +0000 | [diff] [blame] | 190 | for (i = 0; i < numdummies && !err; i++) { |
Patrick McHardy | 206c9fb | 2007-06-13 12:04:20 -0700 | [diff] [blame] | 191 | err = dummy_init_one(); |
Eric Dumazet | 16b0dc2 | 2012-06-10 21:11:57 +0000 | [diff] [blame] | 192 | cond_resched(); |
| 193 | } |
Patrick McHardy | 2d85cba | 2007-07-11 19:42:13 -0700 | [diff] [blame] | 194 | if (err < 0) |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 195 | __rtnl_link_unregister(&dummy_link_ops); |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 196 | rtnl_unlock(); |
| 197 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 198 | return err; |
Jeff Garzik | 6aa20a2 | 2006-09-13 13:24:59 -0400 | [diff] [blame] | 199 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 200 | |
| 201 | static void __exit dummy_cleanup_module(void) |
| 202 | { |
Patrick McHardy | 2d85cba | 2007-07-11 19:42:13 -0700 | [diff] [blame] | 203 | rtnl_link_unregister(&dummy_link_ops); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 204 | } |
| 205 | |
| 206 | module_init(dummy_init_module); |
| 207 | module_exit(dummy_cleanup_module); |
| 208 | MODULE_LICENSE("GPL"); |
Patrick McHardy | 5d5cb17 | 2007-06-13 12:04:34 -0700 | [diff] [blame] | 209 | MODULE_ALIAS_RTNL_LINK("dummy"); |