1 /* 2 * INET An implementation of the TCP/IP protocol suite for the LINUX 3 * operating system. INET is implemented using the BSD Socket 4 * interface as the means of communication with the user level. 5 * 6 * Pseudo-driver for the loopback interface. 7 * 8 * Version: @(#)loopback.c 1.0.4b 08/16/93 9 * 10 * Authors: Ross Biro 11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 12 * Donald Becker, <becker@scyld.com> 13 * 14 * Alan Cox : Fixed oddments for NET3.014 15 * Alan Cox : Rejig for NET3.029 snap #3 16 * Alan Cox : Fixed NET3.029 bugs and sped up 17 * Larry McVoy : Tiny tweak to double performance 18 * Alan Cox : Backed out LMV's tweak - the linux mm 19 * can't take it... 20 * Michael Griffith: Don't bother computing the checksums 21 * on packets received on the loopback 22 * interface. 23 * Alexey Kuznetsov: Potential hang under some extreme 24 * cases removed. 25 * 26 * This program is free software; you can redistribute it and/or 27 * modify it under the terms of the GNU General Public License 28 * as published by the Free Software Foundation; either version 29 * 2 of the License, or (at your option) any later version. 30 */ 31 #include <linux/kernel.h> 32 #include <linux/jiffies.h> 33 #include <linux/module.h> 34 #include <linux/interrupt.h> 35 #include <linux/fs.h> 36 #include <linux/types.h> 37 #include <linux/string.h> 38 #include <linux/socket.h> 39 #include <linux/errno.h> 40 #include <linux/fcntl.h> 41 #include <linux/in.h> 42 #include <linux/init.h> 43 44 #include <asm/system.h> 45 #include <asm/uaccess.h> 46 #include <asm/io.h> 47 48 #include <linux/inet.h> 49 #include <linux/netdevice.h> 50 #include <linux/etherdevice.h> 51 #include <linux/skbuff.h> 52 #include <linux/ethtool.h> 53 #include <net/sock.h> 54 #include <net/checksum.h> 55 #include <linux/if_ether.h> /* For the statistics structure. */ 56 #include <linux/if_arp.h> /* For ARPHRD_ETHER */ 57 #include <linux/ip.h> 58 #include <linux/tcp.h> 59 #include <linux/percpu.h> 60 #include <net/net_namespace.h> 61 62 struct pcpu_lstats { 63 unsigned long packets; 64 unsigned long bytes; 65 }; 66 67 /* 68 * The higher levels take care of making this non-reentrant (it's 69 * called with bh's disabled). 70 */ 71 static int loopback_xmit(struct sk_buff *skb, struct net_device *dev) 72 { 73 struct pcpu_lstats *pcpu_lstats, *lb_stats; 74 75 skb_orphan(skb); 76 77 skb->protocol = eth_type_trans(skb,dev); 78 79 /* it's OK to use per_cpu_ptr() because BHs are off */ 80 pcpu_lstats = dev->ml_priv; 81 lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id()); 82 lb_stats->bytes += skb->len; 83 lb_stats->packets++; 84 85 netif_rx(skb); 86 87 return 0; 88 } 89 90 static struct net_device_stats *loopback_get_stats(struct net_device *dev) 91 { 92 const struct pcpu_lstats *pcpu_lstats; 93 struct net_device_stats *stats = &dev->stats; 94 unsigned long bytes = 0; 95 unsigned long packets = 0; 96 int i; 97 98 pcpu_lstats = dev->ml_priv; 99 for_each_possible_cpu(i) { 100 const struct pcpu_lstats *lb_stats; 101 102 lb_stats = per_cpu_ptr(pcpu_lstats, i); 103 bytes += lb_stats->bytes; 104 packets += lb_stats->packets; 105 } 106 stats->rx_packets = packets; 107 stats->tx_packets = packets; 108 stats->rx_bytes = bytes; 109 stats->tx_bytes = bytes; 110 return stats; 111 } 112 113 static u32 always_on(struct net_device *dev) 114 { 115 return 1; 116 } 117 118 static const struct ethtool_ops loopback_ethtool_ops = { 119 .get_link = always_on, 120 .set_tso = ethtool_op_set_tso, 121 .get_tx_csum = always_on, 122 .get_sg = always_on, 123 .get_rx_csum = always_on, 124 }; 125 126 static int loopback_dev_init(struct net_device *dev) 127 { 128 struct pcpu_lstats *lstats; 129 130 lstats = alloc_percpu(struct pcpu_lstats); 131 if (!lstats) 132 return -ENOMEM; 133 134 dev->ml_priv = lstats; 135 return 0; 136 } 137 138 static void loopback_dev_free(struct net_device *dev) 139 { 140 struct pcpu_lstats *lstats = dev->ml_priv; 141 142 free_percpu(lstats); 143 free_netdev(dev); 144 } 145 146 static const struct net_device_ops loopback_ops = { 147 .ndo_init = loopback_dev_init, 148 .ndo_start_xmit= loopback_xmit, 149 .ndo_get_stats = loopback_get_stats, 150 }; 151 152 /* 153 * The loopback device is special. There is only one instance 154 * per network namespace. 155 */ 156 static void loopback_setup(struct net_device *dev) 157 { 158 dev->mtu = (16 * 1024) + 20 + 20 + 12; 159 dev->hard_header_len = ETH_HLEN; /* 14 */ 160 dev->addr_len = ETH_ALEN; /* 6 */ 161 dev->tx_queue_len = 0; 162 dev->type = ARPHRD_LOOPBACK; /* 0x0001*/ 163 dev->flags = IFF_LOOPBACK; 164 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST 165 | NETIF_F_TSO 166 | NETIF_F_NO_CSUM 167 | NETIF_F_HIGHDMA 168 | NETIF_F_LLTX 169 | NETIF_F_NETNS_LOCAL; 170 dev->ethtool_ops = &loopback_ethtool_ops; 171 dev->header_ops = ð_header_ops; 172 dev->netdev_ops = &loopback_ops; 173 dev->destructor = loopback_dev_free; 174 } 175 176 /* Setup and register the loopback device. */ 177 static __net_init int loopback_net_init(struct net *net) 178 { 179 struct net_device *dev; 180 int err; 181 182 err = -ENOMEM; 183 dev = alloc_netdev(0, "lo", loopback_setup); 184 if (!dev) 185 goto out; 186 187 dev_net_set(dev, net); 188 err = register_netdev(dev); 189 if (err) 190 goto out_free_netdev; 191 192 net->loopback_dev = dev; 193 return 0; 194 195 196 out_free_netdev: 197 free_netdev(dev); 198 out: 199 if (net == &init_net) 200 panic("loopback: Failed to register netdevice: %d\n", err); 201 return err; 202 } 203 204 static __net_exit void loopback_net_exit(struct net *net) 205 { 206 struct net_device *dev = net->loopback_dev; 207 208 unregister_netdev(dev); 209 } 210 211 /* Registered in net/core/dev.c */ 212 struct pernet_operations __net_initdata loopback_net_ops = { 213 .init = loopback_net_init, 214 .exit = loopback_net_exit, 215 }; 216