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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 *
Jesper Juhl02c30a82005-05-05 16:16:16 -070010 * Authors: Ross Biro
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 * 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
Eric Dumazet5175c372006-10-18 20:51:57 -070061struct pcpu_lstats {
62 unsigned long packets;
63 unsigned long bytes;
64};
65static DEFINE_PER_CPU(struct pcpu_lstats, pcpu_lstats);
Linus Torvalds1da177e2005-04-16 15:20:36 -070066
67#define LOOPBACK_OVERHEAD (128 + MAX_HEADER + 16 + 16)
68
69/* KISS: just allocate small chunks and copy bits.
70 *
71 * So, in fact, this is documentation, explaining what we expect
72 * of largesending device modulo TCP checksum, which is ignored for loopback.
73 */
74
Chuck Ebbertd2ae1d22005-07-02 21:28:21 -040075#ifdef LOOPBACK_TSO
Linus Torvalds1da177e2005-04-16 15:20:36 -070076static void emulate_large_send_offload(struct sk_buff *skb)
77{
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070078 struct iphdr *iph = ip_hdr(skb);
Arnaldo Carvalho de Melod56f90a2007-04-10 20:50:43 -070079 struct tcphdr *th = (struct tcphdr *)(skb_network_header(skb) +
80 (iph->ihl * 4));
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 unsigned int doffset = (iph->ihl + th->doff) * 4;
Herbert Xu79671682006-06-22 02:40:14 -070082 unsigned int mtu = skb_shinfo(skb)->gso_size + doffset;
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 unsigned int offset = 0;
84 u32 seq = ntohl(th->seq);
85 u16 id = ntohs(iph->id);
86
87 while (offset + doffset < skb->len) {
88 unsigned int frag_size = min(mtu, skb->len - offset) - doffset;
89 struct sk_buff *nskb = alloc_skb(mtu + 32, GFP_ATOMIC);
90
91 if (!nskb)
92 break;
93 skb_reserve(nskb, 32);
Arnaldo Carvalho de Melo48d49d0c2007-03-10 12:30:58 -030094 skb_set_mac_header(nskb, -ETH_HLEN);
Arnaldo Carvalho de Meloc1d2bbe2007-04-10 20:45:18 -070095 skb_reset_network_header(nskb);
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070096 iph = ip_hdr(nskb);
Arnaldo Carvalho de Melod56f90a2007-04-10 20:50:43 -070097 memcpy(nskb->data, skb_network_header(skb), doffset);
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 if (skb_copy_bits(skb,
99 doffset + offset,
100 nskb->data + doffset,
101 frag_size))
102 BUG();
103 skb_put(nskb, doffset + frag_size);
104 nskb->ip_summed = CHECKSUM_UNNECESSARY;
105 nskb->dev = skb->dev;
106 nskb->priority = skb->priority;
107 nskb->protocol = skb->protocol;
108 nskb->dst = dst_clone(skb->dst);
109 memcpy(nskb->cb, skb->cb, sizeof(skb->cb));
110 nskb->pkt_type = skb->pkt_type;
111
Arnaldo Carvalho de Melod56f90a2007-04-10 20:50:43 -0700112 th = (struct tcphdr *)(skb_network_header(nskb) + iph->ihl * 4);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 iph->tot_len = htons(frag_size + doffset);
114 iph->id = htons(id);
115 iph->check = 0;
116 iph->check = ip_fast_csum((unsigned char *) iph, iph->ihl);
117 th->seq = htonl(seq);
118 if (offset + doffset + frag_size < skb->len)
119 th->fin = th->psh = 0;
120 netif_rx(nskb);
121 offset += frag_size;
122 seq += frag_size;
123 id++;
124 }
125
126 dev_kfree_skb(skb);
127}
Chuck Ebbertd2ae1d22005-07-02 21:28:21 -0400128#endif /* LOOPBACK_TSO */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
130/*
131 * The higher levels take care of making this non-reentrant (it's
132 * called with bh's disabled).
133 */
134static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
135{
Eric Dumazet5175c372006-10-18 20:51:57 -0700136 struct pcpu_lstats *lb_stats;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137
138 skb_orphan(skb);
139
Chuck Ebbert0e920bf2005-07-02 21:28:23 -0400140 skb->protocol = eth_type_trans(skb,dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141#ifndef LOOPBACK_MUST_CHECKSUM
142 skb->ip_summed = CHECKSUM_UNNECESSARY;
143#endif
144
Chuck Ebbertd2ae1d22005-07-02 21:28:21 -0400145#ifdef LOOPBACK_TSO
Herbert Xu89114af2006-07-08 13:34:32 -0700146 if (skb_is_gso(skb)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 BUG_ON(skb->protocol != htons(ETH_P_IP));
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700148 BUG_ON(ip_hdr(skb)->protocol != IPPROTO_TCP);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149
150 emulate_large_send_offload(skb);
151 return 0;
152 }
Chuck Ebbertd2ae1d22005-07-02 21:28:21 -0400153#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 dev->last_rx = jiffies;
155
Eric Dumazet58f53972006-10-20 00:32:41 -0700156 /* it's OK to use __get_cpu_var() because BHs are off */
157 lb_stats = &__get_cpu_var(pcpu_lstats);
Eric Dumazet5175c372006-10-18 20:51:57 -0700158 lb_stats->bytes += skb->len;
159 lb_stats->packets++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160
161 netif_rx(skb);
162
Eric Dumazet58f53972006-10-20 00:32:41 -0700163 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164}
165
Stephen Hemminger7fa6b062006-09-27 20:33:34 -0700166static struct net_device_stats loopback_stats;
167
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168static struct net_device_stats *get_stats(struct net_device *dev)
169{
Stephen Hemminger7fa6b062006-09-27 20:33:34 -0700170 struct net_device_stats *stats = &loopback_stats;
Eric Dumazet5175c372006-10-18 20:51:57 -0700171 unsigned long bytes = 0;
172 unsigned long packets = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 int i;
174
KAMEZAWA Hiroyuki0fed4842006-03-28 01:56:37 -0800175 for_each_possible_cpu(i) {
Eric Dumazet5175c372006-10-18 20:51:57 -0700176 const struct pcpu_lstats *lb_stats;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177
Eric Dumazet5175c372006-10-18 20:51:57 -0700178 lb_stats = &per_cpu(pcpu_lstats, i);
179 bytes += lb_stats->bytes;
180 packets += lb_stats->packets;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 }
Eric Dumazet5175c372006-10-18 20:51:57 -0700182 stats->rx_packets = packets;
183 stats->tx_packets = packets;
184 stats->rx_bytes = bytes;
185 stats->tx_bytes = bytes;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 return stats;
187}
188
Stephen Hemminger7fa6b062006-09-27 20:33:34 -0700189static u32 always_on(struct net_device *dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190{
191 return 1;
192}
193
Jeff Garzik7282d492006-09-13 14:30:00 -0400194static const struct ethtool_ops loopback_ethtool_ops = {
Stephen Hemminger7fa6b062006-09-27 20:33:34 -0700195 .get_link = always_on,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 .get_tso = ethtool_op_get_tso,
197 .set_tso = ethtool_op_set_tso,
Stephen Hemminger7fa6b062006-09-27 20:33:34 -0700198 .get_tx_csum = always_on,
199 .get_sg = always_on,
200 .get_rx_csum = always_on,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201};
202
Stephen Hemminger7fa6b062006-09-27 20:33:34 -0700203/*
204 * The loopback device is special. There is only one instance and
205 * it is statically allocated. Don't do this for other devices.
206 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207struct net_device loopback_dev = {
208 .name = "lo",
Stephen Hemminger7fa6b062006-09-27 20:33:34 -0700209 .get_stats = &get_stats,
210 .priv = &loopback_stats,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 .mtu = (16 * 1024) + 20 + 20 + 12,
212 .hard_start_xmit = loopback_xmit,
213 .hard_header = eth_header,
214 .hard_header_cache = eth_header_cache,
215 .header_cache_update = eth_header_cache_update,
216 .hard_header_len = ETH_HLEN, /* 14 */
217 .addr_len = ETH_ALEN, /* 6 */
218 .tx_queue_len = 0,
219 .type = ARPHRD_LOOPBACK, /* 0x0001*/
220 .rebuild_header = eth_rebuild_header,
221 .flags = IFF_LOOPBACK,
Chuck Ebbert0e920bf2005-07-02 21:28:23 -0400222 .features = NETIF_F_SG | NETIF_F_FRAGLIST
Chuck Ebbertd2ae1d22005-07-02 21:28:21 -0400223#ifdef LOOPBACK_TSO
Chuck Ebbert0e920bf2005-07-02 21:28:23 -0400224 | NETIF_F_TSO
Chuck Ebbertd2ae1d22005-07-02 21:28:21 -0400225#endif
Chuck Ebbert0e920bf2005-07-02 21:28:23 -0400226 | NETIF_F_NO_CSUM | NETIF_F_HIGHDMA
227 | NETIF_F_LLTX,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 .ethtool_ops = &loopback_ethtool_ops,
229};
230
Ralf Baechle22783642005-08-18 14:05:18 -0700231/* Setup and register the loopback device. */
Adrian Bunk60903f22007-01-02 00:35:48 -0800232static int __init loopback_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 return register_netdev(&loopback_dev);
235};
236
Adrian Bunk60903f22007-01-02 00:35:48 -0800237module_init(loopback_init);
238
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239EXPORT_SYMBOL(loopback_dev);