| 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 | unsigned long drops; |
| 66 | }; |
| 67 | |
| 68 | /* |
| 69 | * The higher levels take care of making this non-reentrant (it's |
| 70 | * called with bh's disabled). |
| 71 | */ |
| 72 | static netdev_tx_t loopback_xmit(struct sk_buff *skb, |
| 73 | struct net_device *dev) |
| 74 | { |
| 75 | struct pcpu_lstats *pcpu_lstats, *lb_stats; |
| 76 | int len; |
| 77 | |
| 78 | skb_orphan(skb); |
| 79 | |
| 80 | skb->protocol = eth_type_trans(skb, dev); |
| 81 | |
| 82 | /* it's OK to use per_cpu_ptr() because BHs are off */ |
| 83 | pcpu_lstats = dev->ml_priv; |
| 84 | lb_stats = this_cpu_ptr(pcpu_lstats); |
| 85 | |
| 86 | len = skb->len; |
| 87 | if (likely(netif_rx(skb) == NET_RX_SUCCESS)) { |
| 88 | lb_stats->bytes += len; |
| 89 | lb_stats->packets++; |
| 90 | } else |
| 91 | lb_stats->drops++; |
| 92 | |
| 93 | return NETDEV_TX_OK; |
| 94 | } |
| 95 | |
| 96 | static struct net_device_stats *loopback_get_stats(struct net_device *dev) |
| 97 | { |
| 98 | const struct pcpu_lstats *pcpu_lstats; |
| 99 | struct net_device_stats *stats = &dev->stats; |
| 100 | unsigned long bytes = 0; |
| 101 | unsigned long packets = 0; |
| 102 | unsigned long drops = 0; |
| 103 | int i; |
| 104 | |
| 105 | pcpu_lstats = dev->ml_priv; |
| 106 | for_each_possible_cpu(i) { |
| 107 | const struct pcpu_lstats *lb_stats; |
| 108 | |
| 109 | lb_stats = per_cpu_ptr(pcpu_lstats, i); |
| 110 | bytes += lb_stats->bytes; |
| 111 | packets += lb_stats->packets; |
| 112 | drops += lb_stats->drops; |
| 113 | } |
| 114 | stats->rx_packets = packets; |
| 115 | stats->tx_packets = packets; |
| 116 | stats->rx_dropped = drops; |
| 117 | stats->rx_errors = drops; |
| 118 | stats->rx_bytes = bytes; |
| 119 | stats->tx_bytes = bytes; |
| 120 | return stats; |
| 121 | } |
| 122 | |
| 123 | static u32 always_on(struct net_device *dev) |
| 124 | { |
| 125 | return 1; |
| 126 | } |
| 127 | |
| 128 | static const struct ethtool_ops loopback_ethtool_ops = { |
| 129 | .get_link = always_on, |
| 130 | .set_tso = ethtool_op_set_tso, |
| 131 | .get_tx_csum = always_on, |
| 132 | .get_sg = always_on, |
| 133 | .get_rx_csum = always_on, |
| 134 | }; |
| 135 | |
| 136 | static int loopback_dev_init(struct net_device *dev) |
| 137 | { |
| 138 | struct pcpu_lstats *lstats; |
| 139 | |
| 140 | lstats = alloc_percpu(struct pcpu_lstats); |
| 141 | if (!lstats) |
| 142 | return -ENOMEM; |
| 143 | |
| 144 | dev->ml_priv = lstats; |
| 145 | return 0; |
| 146 | } |
| 147 | |
| 148 | static void loopback_dev_free(struct net_device *dev) |
| 149 | { |
| 150 | struct pcpu_lstats *lstats = dev->ml_priv; |
| 151 | |
| 152 | free_percpu(lstats); |
| 153 | free_netdev(dev); |
| 154 | } |
| 155 | |
| 156 | static const struct net_device_ops loopback_ops = { |
| 157 | .ndo_init = loopback_dev_init, |
| 158 | .ndo_start_xmit= loopback_xmit, |
| 159 | .ndo_get_stats = loopback_get_stats, |
| 160 | }; |
| 161 | |
| 162 | /* |
| 163 | * The loopback device is special. There is only one instance |
| 164 | * per network namespace. |
| 165 | */ |
| 166 | static void loopback_setup(struct net_device *dev) |
| 167 | { |
| 168 | dev->mtu = (16 * 1024) + 20 + 20 + 12; |
| 169 | dev->hard_header_len = ETH_HLEN; /* 14 */ |
| 170 | dev->addr_len = ETH_ALEN; /* 6 */ |
| 171 | dev->tx_queue_len = 0; |
| 172 | dev->type = ARPHRD_LOOPBACK; /* 0x0001*/ |
| 173 | dev->flags = IFF_LOOPBACK; |
| 174 | dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; |
| 175 | dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
| 176 | | NETIF_F_TSO |
| 177 | | NETIF_F_NO_CSUM |
| 178 | | NETIF_F_HIGHDMA |
| 179 | | NETIF_F_LLTX |
| 180 | | NETIF_F_NETNS_LOCAL; |
| 181 | dev->ethtool_ops = &loopback_ethtool_ops; |
| 182 | dev->header_ops = ð_header_ops; |
| 183 | dev->netdev_ops = &loopback_ops; |
| 184 | dev->destructor = loopback_dev_free; |
| 185 | } |
| 186 | |
| 187 | /* Setup and register the loopback device. */ |
| 188 | static __net_init int loopback_net_init(struct net *net) |
| 189 | { |
| 190 | struct net_device *dev; |
| 191 | int err; |
| 192 | |
| 193 | err = -ENOMEM; |
| 194 | dev = alloc_netdev(0, "lo", loopback_setup); |
| 195 | if (!dev) |
| 196 | goto out; |
| 197 | |
| 198 | dev_net_set(dev, net); |
| 199 | err = register_netdev(dev); |
| 200 | if (err) |
| 201 | goto out_free_netdev; |
| 202 | |
| 203 | net->loopback_dev = dev; |
| 204 | return 0; |
| 205 | |
| 206 | |
| 207 | out_free_netdev: |
| 208 | free_netdev(dev); |
| 209 | out: |
| 210 | if (net_eq(net, &init_net)) |
| 211 | panic("loopback: Failed to register netdevice: %d\n", err); |
| 212 | return err; |
| 213 | } |
| 214 | |
| 215 | /* Registered in net/core/dev.c */ |
| 216 | struct pernet_operations __net_initdata loopback_net_ops = { |
| 217 | .init = loopback_net_init, |
| 218 | }; |