projects/linux·blob v4.4 · refs

222 lines · 5.6 KiB

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, <[email protected]>
12 * Donald Becker, <[email protected]>
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
43#include <asm/uaccess.h>
44#include <asm/io.h>
45
46#include <linux/inet.h>
47#include <linux/netdevice.h>
48#include <linux/etherdevice.h>
49#include <linux/skbuff.h>
50#include <linux/ethtool.h>
51#include <net/sock.h>
52#include <net/checksum.h>
53#include <linux/if_ether.h> /* For the statistics structure. */
54#include <linux/if_arp.h> /* For ARPHRD_ETHER */
55#include <linux/ip.h>
56#include <linux/tcp.h>
57#include <linux/percpu.h>
58#include <net/net_namespace.h>
59#include <linux/u64_stats_sync.h>
60
61struct pcpu_lstats {
62 u64 packets;
63 u64 bytes;
64 struct u64_stats_sync syncp;
65};
66
67/*
68 * The higher levels take care of making this non-reentrant (it's
69 * called with bh's disabled).
70 */
71static netdev_tx_t loopback_xmit(struct sk_buff *skb,
72 struct net_device *dev)
73{
74 struct pcpu_lstats *lb_stats;
75 int len;
76
77 skb_orphan(skb);
78
79 /* Before queueing this packet to netif_rx(),
80 * make sure dst is refcounted.
81 */
82 skb_dst_force(skb);
83
84 skb->protocol = eth_type_trans(skb, dev);
85
86 /* it's OK to use per_cpu_ptr() because BHs are off */
87 lb_stats = this_cpu_ptr(dev->lstats);
88
89 len = skb->len;
90 if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {
91 u64_stats_update_begin(&lb_stats->syncp);
92 lb_stats->bytes += len;
93 lb_stats->packets++;
94 u64_stats_update_end(&lb_stats->syncp);
95 }
96
97 return NETDEV_TX_OK;
98}
99
100static struct rtnl_link_stats64 *loopback_get_stats64(struct net_device *dev,
101 struct rtnl_link_stats64 *stats)
102{
103 u64 bytes = 0;
104 u64 packets = 0;
105 int i;
106
107 for_each_possible_cpu(i) {
108 const struct pcpu_lstats *lb_stats;
109 u64 tbytes, tpackets;
110 unsigned int start;
111
112 lb_stats = per_cpu_ptr(dev->lstats, i);
113 do {
114 start = u64_stats_fetch_begin_irq(&lb_stats->syncp);
115 tbytes = lb_stats->bytes;
116 tpackets = lb_stats->packets;
117 } while (u64_stats_fetch_retry_irq(&lb_stats->syncp, start));
118 bytes += tbytes;
119 packets += tpackets;
120 }
121 stats->rx_packets = packets;
122 stats->tx_packets = packets;
123 stats->rx_bytes = bytes;
124 stats->tx_bytes = bytes;
125 return stats;
126}
127
128static u32 always_on(struct net_device *dev)
129{
130 return 1;
131}
132
133static const struct ethtool_ops loopback_ethtool_ops = {
134 .get_link = always_on,
135};
136
137static int loopback_dev_init(struct net_device *dev)
138{
139 dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
140 if (!dev->lstats)
141 return -ENOMEM;
142 return 0;
143}
144
145static void loopback_dev_free(struct net_device *dev)
146{
147 dev_net(dev)->loopback_dev = NULL;
148 free_percpu(dev->lstats);
149 free_netdev(dev);
150}
151
152static const struct net_device_ops loopback_ops = {
153 .ndo_init = loopback_dev_init,
154 .ndo_start_xmit= loopback_xmit,
155 .ndo_get_stats64 = loopback_get_stats64,
156 .ndo_set_mac_address = eth_mac_addr,
157};
158
159/*
160 * The loopback device is special. There is only one instance
161 * per network namespace.
162 */
163static void loopback_setup(struct net_device *dev)
164{
165 dev->mtu = 64 * 1024;
166 dev->hard_header_len = ETH_HLEN; /* 14 */
167 dev->addr_len = ETH_ALEN; /* 6 */
168 dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
169 dev->flags = IFF_LOOPBACK;
170 dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE;
171 netif_keep_dst(dev);
172 dev->hw_features = NETIF_F_ALL_TSO | NETIF_F_UFO;
173 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
174 | NETIF_F_ALL_TSO
175 | NETIF_F_UFO
176 | NETIF_F_HW_CSUM
177 | NETIF_F_RXCSUM
178 | NETIF_F_SCTP_CSUM
179 | NETIF_F_HIGHDMA
180 | NETIF_F_LLTX
181 | NETIF_F_NETNS_LOCAL
182 | NETIF_F_VLAN_CHALLENGED
183 | NETIF_F_LOOPBACK;
184 dev->ethtool_ops = &loopback_ethtool_ops;
185 dev->header_ops = &eth_header_ops;
186 dev->netdev_ops = &loopback_ops;
187 dev->destructor = loopback_dev_free;
188}
189
190/* Setup and register the loopback device. */
191static __net_init int loopback_net_init(struct net *net)
192{
193 struct net_device *dev;
194 int err;
195
196 err = -ENOMEM;
197 dev = alloc_netdev(0, "lo", NET_NAME_UNKNOWN, loopback_setup);
198 if (!dev)
199 goto out;
200
201 dev_net_set(dev, net);
202 err = register_netdev(dev);
203 if (err)
204 goto out_free_netdev;
205
206 BUG_ON(dev->ifindex != LOOPBACK_IFINDEX);
207 net->loopback_dev = dev;
208 return 0;
209
210
211out_free_netdev:
212 free_netdev(dev);
213out:
214 if (net_eq(net, &init_net))
215 panic("loopback: Failed to register netdevice: %d\n", err);
216 return err;
217}
218
219/* Registered in net/core/dev.c */
220struct pernet_operations __net_initdata loopback_net_ops = {
221 .init = loopback_net_init,
222};