Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 | /*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Pseudo-driver for the loopback interface.
*
* Version: @(#)loopback.c 1.0.4b 08/16/93
*
* Authors: Ross Biro
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
* Donald Becker, <becker@scyld.com>
*
* Alan Cox : Fixed oddments for NET3.014
* Alan Cox : Rejig for NET3.029 snap #3
* Alan Cox : Fixed NET3.029 bugs and sped up
* Larry McVoy : Tiny tweak to double performance
* Alan Cox : Backed out LMV's tweak - the linux mm
* can't take it...
* Michael Griffith: Don't bother computing the checksums
* on packets received on the loopback
* interface.
* Alexey Kuznetsov: Potential hang under some extreme
* cases removed.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/in.h>
#include <linux/init.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/ethtool.h>
#include <net/sock.h>
#include <net/checksum.h>
#include <linux/if_ether.h> /* For the statistics structure. */
#include <linux/if_arp.h> /* For ARPHRD_ETHER */
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/percpu.h>
struct pcpu_lstats {
unsigned long packets;
unsigned long bytes;
};
static DEFINE_PER_CPU(struct pcpu_lstats, pcpu_lstats);
#define LOOPBACK_OVERHEAD (128 + MAX_HEADER + 16 + 16)
/* KISS: just allocate small chunks and copy bits.
*
* So, in fact, this is documentation, explaining what we expect
* of largesending device modulo TCP checksum, which is ignored for loopback.
*/
#ifdef LOOPBACK_TSO
static void emulate_large_send_offload(struct sk_buff *skb)
{
struct iphdr *iph = ip_hdr(skb);
struct tcphdr *th = (struct tcphdr *)(skb_network_header(skb) +
(iph->ihl * 4));
unsigned int doffset = (iph->ihl + th->doff) * 4;
unsigned int mtu = skb_shinfo(skb)->gso_size + doffset;
unsigned int offset = 0;
u32 seq = ntohl(th->seq);
u16 id = ntohs(iph->id);
while (offset + doffset < skb->len) {
unsigned int frag_size = min(mtu, skb->len - offset) - doffset;
struct sk_buff *nskb = alloc_skb(mtu + 32, GFP_ATOMIC);
if (!nskb)
break;
skb_reserve(nskb, 32);
skb_set_mac_header(nskb, -ETH_HLEN);
skb_reset_network_header(nskb);
iph = ip_hdr(nskb);
skb_copy_to_linear_data(nskb, skb_network_header(skb),
doffset);
if (skb_copy_bits(skb,
doffset + offset,
nskb->data + doffset,
frag_size))
BUG();
skb_put(nskb, doffset + frag_size);
nskb->ip_summed = CHECKSUM_UNNECESSARY;
nskb->dev = skb->dev;
nskb->priority = skb->priority;
nskb->protocol = skb->protocol;
nskb->dst = dst_clone(skb->dst);
memcpy(nskb->cb, skb->cb, sizeof(skb->cb));
nskb->pkt_type = skb->pkt_type;
th = (struct tcphdr *)(skb_network_header(nskb) + iph->ihl * 4);
iph->tot_len = htons(frag_size + doffset);
iph->id = htons(id);
iph->check = 0;
iph->check = ip_fast_csum((unsigned char *) iph, iph->ihl);
th->seq = htonl(seq);
if (offset + doffset + frag_size < skb->len)
th->fin = th->psh = 0;
netif_rx(nskb);
offset += frag_size;
seq += frag_size;
id++;
}
dev_kfree_skb(skb);
}
#endif /* LOOPBACK_TSO */
/*
* The higher levels take care of making this non-reentrant (it's
* called with bh's disabled).
*/
static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct pcpu_lstats *lb_stats;
skb_orphan(skb);
skb->protocol = eth_type_trans(skb,dev);
#ifndef LOOPBACK_MUST_CHECKSUM
skb->ip_summed = CHECKSUM_UNNECESSARY;
#endif
#ifdef LOOPBACK_TSO
if (skb_is_gso(skb)) {
BUG_ON(skb->protocol != htons(ETH_P_IP));
BUG_ON(ip_hdr(skb)->protocol != IPPROTO_TCP);
emulate_large_send_offload(skb);
return 0;
}
#endif
dev->last_rx = jiffies;
/* it's OK to use __get_cpu_var() because BHs are off */
lb_stats = &__get_cpu_var(pcpu_lstats);
lb_stats->bytes += skb->len;
lb_stats->packets++;
netif_rx(skb);
return 0;
}
static struct net_device_stats *get_stats(struct net_device *dev)
{
struct net_device_stats *stats = &dev->stats;
unsigned long bytes = 0;
unsigned long packets = 0;
int i;
for_each_possible_cpu(i) {
const struct pcpu_lstats *lb_stats;
lb_stats = &per_cpu(pcpu_lstats, i);
bytes += lb_stats->bytes;
packets += lb_stats->packets;
}
stats->rx_packets = packets;
stats->tx_packets = packets;
stats->rx_bytes = bytes;
stats->tx_bytes = bytes;
return stats;
}
static u32 always_on(struct net_device *dev)
{
return 1;
}
static const struct ethtool_ops loopback_ethtool_ops = {
.get_link = always_on,
.get_tso = ethtool_op_get_tso,
.set_tso = ethtool_op_set_tso,
.get_tx_csum = always_on,
.get_sg = always_on,
.get_rx_csum = always_on,
};
/*
* The loopback device is special. There is only one instance and
* it is statically allocated. Don't do this for other devices.
*/
struct net_device loopback_dev = {
.name = "lo",
.get_stats = &get_stats,
.mtu = (16 * 1024) + 20 + 20 + 12,
.hard_start_xmit = loopback_xmit,
.hard_header = eth_header,
.hard_header_cache = eth_header_cache,
.header_cache_update = eth_header_cache_update,
.hard_header_len = ETH_HLEN, /* 14 */
.addr_len = ETH_ALEN, /* 6 */
.tx_queue_len = 0,
.type = ARPHRD_LOOPBACK, /* 0x0001*/
.rebuild_header = eth_rebuild_header,
.flags = IFF_LOOPBACK,
.features = NETIF_F_SG | NETIF_F_FRAGLIST
#ifdef LOOPBACK_TSO
| NETIF_F_TSO
#endif
| NETIF_F_NO_CSUM | NETIF_F_HIGHDMA
| NETIF_F_LLTX,
.ethtool_ops = &loopback_ethtool_ops,
};
/* Setup and register the loopback device. */
static int __init loopback_init(void)
{
return register_netdev(&loopback_dev);
};
module_init(loopback_init);
EXPORT_SYMBOL(loopback_dev);
|