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Thomas Gleixner2874c5f2019-05-27 08:55:01 +02001// SPDX-License-Identifier: GPL-2.0-or-later
Linus Torvalds1da177e2005-04-16 15:20:36 -07002/*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * Pseudo-driver for the loopback interface.
8 *
9 * Version: @(#)loopback.c 1.0.4b 08/16/93
10 *
Jesper Juhl02c30a82005-05-05 16:16:16 -070011 * Authors: Ross Biro
Linus Torvalds1da177e2005-04-16 15:20:36 -070012 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13 * Donald Becker, <becker@scyld.com>
14 *
15 * Alan Cox : Fixed oddments for NET3.014
16 * Alan Cox : Rejig for NET3.029 snap #3
Ezequiel Lara Gomezb3407c82017-03-11 20:06:01 +000017 * Alan Cox : Fixed NET3.029 bugs and sped up
Linus Torvalds1da177e2005-04-16 15:20:36 -070018 * Larry McVoy : Tiny tweak to double performance
19 * Alan Cox : Backed out LMV's tweak - the linux mm
20 * can't take it...
21 * Michael Griffith: Don't bother computing the checksums
22 * on packets received on the loopback
23 * interface.
24 * Alexey Kuznetsov: Potential hang under some extreme
25 * cases removed.
Linus Torvalds1da177e2005-04-16 15:20:36 -070026 */
27#include <linux/kernel.h>
28#include <linux/jiffies.h>
29#include <linux/module.h>
30#include <linux/interrupt.h>
31#include <linux/fs.h>
32#include <linux/types.h>
33#include <linux/string.h>
34#include <linux/socket.h>
35#include <linux/errno.h>
36#include <linux/fcntl.h>
37#include <linux/in.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070038
Linus Torvalds7c0f6ba2016-12-24 11:46:01 -080039#include <linux/uaccess.h>
Ezequiel Lara Gomezb3407c82017-03-11 20:06:01 +000040#include <linux/io.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
42#include <linux/inet.h>
43#include <linux/netdevice.h>
44#include <linux/etherdevice.h>
45#include <linux/skbuff.h>
46#include <linux/ethtool.h>
47#include <net/sock.h>
48#include <net/checksum.h>
49#include <linux/if_ether.h> /* For the statistics structure. */
50#include <linux/if_arp.h> /* For ARPHRD_ETHER */
51#include <linux/ip.h>
52#include <linux/tcp.h>
53#include <linux/percpu.h>
Ezequiel Lara Gomez6df014c2017-03-11 20:06:54 +000054#include <linux/net_tstamp.h>
Eric W. Biederman2774c7a2007-09-26 22:10:56 -070055#include <net/net_namespace.h>
Eric Dumazet5eaa0bd2010-06-22 12:44:11 +000056#include <linux/u64_stats_sync.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070057
Mahesh Bandewar4de83b82019-07-01 14:38:49 -070058/* blackhole_netdev - a device used for dsts that are marked expired!
59 * This is global device (instead of per-net-ns) since it's not needed
60 * to be per-ns and gets initialized at boot time.
61 */
62struct net_device *blackhole_netdev;
63EXPORT_SYMBOL(blackhole_netdev);
64
Ezequiel Lara Gomezb3407c82017-03-11 20:06:01 +000065/* The higher levels take care of making this non-reentrant (it's
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 * called with bh's disabled).
67 */
Stephen Hemminger613573252009-08-31 19:50:58 +000068static netdev_tx_t loopback_xmit(struct sk_buff *skb,
69 struct net_device *dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -070070{
Eric Dumazet7eebb0b2009-04-17 22:03:10 +000071 int len;
Linus Torvalds1da177e2005-04-16 15:20:36 -070072
Ezequiel Lara Gomez6df014c2017-03-11 20:06:54 +000073 skb_tx_timestamp(skb);
Eric Dumazet4c161282018-10-19 19:11:26 -070074
75 /* do not fool net_timestamp_check() with various clock bases */
76 skb->tstamp = 0;
77
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 skb_orphan(skb);
79
Eric Dumazet794ed392013-01-25 07:44:41 +000080 /* Before queueing this packet to netif_rx(),
81 * make sure dst is refcounted.
82 */
83 skb_dst_force(skb);
84
Eric Dumazet7eebb0b2009-04-17 22:03:10 +000085 skb->protocol = eth_type_trans(skb, dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
Eric Dumazet7eebb0b2009-04-17 22:03:10 +000087 len = skb->len;
Eric Dumazetdd5382a2019-11-07 16:27:15 -080088 if (likely(netif_rx(skb) == NET_RX_SUCCESS))
89 dev_lstats_add(dev, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
Patrick McHardy6ed10652009-06-23 06:03:08 +000091 return NETDEV_TX_OK;
Linus Torvalds1da177e2005-04-16 15:20:36 -070092}
93
Eric Dumazetde7d5082019-11-07 16:27:14 -080094void dev_lstats_read(struct net_device *dev, u64 *packets, u64 *bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -070095{
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 int i;
97
Eric Dumazetde7d5082019-11-07 16:27:14 -080098 *packets = 0;
99 *bytes = 0;
100
KAMEZAWA Hiroyuki0fed4842006-03-28 01:56:37 -0800101 for_each_possible_cpu(i) {
Eric Dumazet5175c3782006-10-18 20:51:57 -0700102 const struct pcpu_lstats *lb_stats;
Eric Dumazet5eaa0bd2010-06-22 12:44:11 +0000103 u64 tbytes, tpackets;
104 unsigned int start;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105
Eric Dumazeta7855c72010-09-23 23:51:51 +0000106 lb_stats = per_cpu_ptr(dev->lstats, i);
Eric Dumazet5eaa0bd2010-06-22 12:44:11 +0000107 do {
Eric W. Biederman57a77442014-03-13 21:26:42 -0700108 start = u64_stats_fetch_begin_irq(&lb_stats->syncp);
Eric Dumazetfd2f4732019-11-07 16:27:22 -0800109 tpackets = u64_stats_read(&lb_stats->packets);
110 tbytes = u64_stats_read(&lb_stats->bytes);
Eric W. Biederman57a77442014-03-13 21:26:42 -0700111 } while (u64_stats_fetch_retry_irq(&lb_stats->syncp, start));
Eric Dumazetde7d5082019-11-07 16:27:14 -0800112 *bytes += tbytes;
113 *packets += tpackets;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 }
Eric Dumazetde7d5082019-11-07 16:27:14 -0800115}
116EXPORT_SYMBOL(dev_lstats_read);
117
118static void loopback_get_stats64(struct net_device *dev,
119 struct rtnl_link_stats64 *stats)
120{
121 u64 packets, bytes;
122
123 dev_lstats_read(dev, &packets, &bytes);
124
Eric Dumazet5175c3782006-10-18 20:51:57 -0700125 stats->rx_packets = packets;
126 stats->tx_packets = packets;
Eric Dumazet7eebb0b2009-04-17 22:03:10 +0000127 stats->rx_bytes = bytes;
128 stats->tx_bytes = bytes;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129}
130
Stephen Hemminger7fa6b062006-09-27 20:33:34 -0700131static u32 always_on(struct net_device *dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132{
133 return 1;
134}
135
Jeff Garzik7282d492006-09-13 14:30:00 -0400136static const struct ethtool_ops loopback_ethtool_ops = {
Stephen Hemminger7fa6b062006-09-27 20:33:34 -0700137 .get_link = always_on,
Julian Wiedmannaf730342019-04-12 13:06:14 +0200138 .get_ts_info = ethtool_op_get_ts_info,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139};
140
Eric W. Biederman5f6d88b2007-09-26 22:08:12 -0700141static int loopback_dev_init(struct net_device *dev)
142{
WANG Cong1c213bd2014-02-13 11:46:28 -0800143 dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
Eric Dumazeta7855c72010-09-23 23:51:51 +0000144 if (!dev->lstats)
Eric W. Biederman5f6d88b2007-09-26 22:08:12 -0700145 return -ENOMEM;
Eric W. Biederman5f6d88b2007-09-26 22:08:12 -0700146 return 0;
147}
148
149static void loopback_dev_free(struct net_device *dev)
150{
Eric W. Biedermane05e9072013-09-16 16:52:41 -0700151 dev_net(dev)->loopback_dev = NULL;
Eric Dumazeta7855c72010-09-23 23:51:51 +0000152 free_percpu(dev->lstats);
Eric W. Biederman5f6d88b2007-09-26 22:08:12 -0700153}
154
Stephen Hemmingerc02373bf2008-11-19 21:46:18 -0800155static const struct net_device_ops loopback_ops = {
Ezequiel Lara Gomezb3407c82017-03-11 20:06:01 +0000156 .ndo_init = loopback_dev_init,
157 .ndo_start_xmit = loopback_xmit,
Eric Dumazet6b10de32010-06-14 05:59:22 +0000158 .ndo_get_stats64 = loopback_get_stats64,
WANG Cong25f929f2014-02-11 17:21:26 -0800159 .ndo_set_mac_address = eth_mac_addr,
Stephen Hemmingerc02373bf2008-11-19 21:46:18 -0800160};
161
Mahesh Bandewar4de83b82019-07-01 14:38:49 -0700162static void gen_lo_setup(struct net_device *dev,
163 unsigned int mtu,
164 const struct ethtool_ops *eth_ops,
165 const struct header_ops *hdr_ops,
166 const struct net_device_ops *dev_ops,
167 void (*dev_destructor)(struct net_device *dev))
Daniel Lezcano854d8362007-09-25 19:18:04 -0700168{
Mahesh Bandewar4de83b82019-07-01 14:38:49 -0700169 dev->mtu = mtu;
Daniel Lezcano854d8362007-09-25 19:18:04 -0700170 dev->hard_header_len = ETH_HLEN; /* 14 */
Willem de Bruijn217e6fa2017-02-07 15:57:20 -0500171 dev->min_header_len = ETH_HLEN; /* 14 */
Daniel Lezcano854d8362007-09-25 19:18:04 -0700172 dev->addr_len = ETH_ALEN; /* 6 */
Daniel Lezcano854d8362007-09-25 19:18:04 -0700173 dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
Daniel Lezcano854d8362007-09-25 19:18:04 -0700174 dev->flags = IFF_LOOPBACK;
Phil Suttere65db2b2015-08-18 10:30:32 +0200175 dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE;
Eric Dumazet02875872014-10-05 18:38:35 -0700176 netif_keep_dst(dev);
Marcelo Ricardo Leitnerf6c382f2016-06-02 15:05:38 -0300177 dev->hw_features = NETIF_F_GSO_SOFTWARE;
Ezequiel Lara Gomezb3407c82017-03-11 20:06:01 +0000178 dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
Marcelo Ricardo Leitnerf6c382f2016-06-02 15:05:38 -0300179 | NETIF_F_GSO_SOFTWARE
Michał Mirosław34324dc2011-11-15 15:29:55 +0000180 | NETIF_F_HW_CSUM
Michał Mirosławcf0bdef2011-02-15 16:59:18 +0000181 | NETIF_F_RXCSUM
Tom Herbert53692b12015-12-14 11:19:41 -0800182 | NETIF_F_SCTP_CRC
Daniel Lezcano854d8362007-09-25 19:18:04 -0700183 | NETIF_F_HIGHDMA
184 | NETIF_F_LLTX
Krishna Kumar0553c892011-04-14 06:07:04 +0000185 | NETIF_F_NETNS_LOCAL
Mahesh Bandewareed2a122011-05-04 15:30:11 +0000186 | NETIF_F_VLAN_CHALLENGED
187 | NETIF_F_LOOPBACK;
Mahesh Bandewar4de83b82019-07-01 14:38:49 -0700188 dev->ethtool_ops = eth_ops;
189 dev->header_ops = hdr_ops;
190 dev->netdev_ops = dev_ops;
David S. Millercf124db2017-05-08 12:52:56 -0400191 dev->needs_free_netdev = true;
Mahesh Bandewar4de83b82019-07-01 14:38:49 -0700192 dev->priv_destructor = dev_destructor;
193}
194
195/* The loopback device is special. There is only one instance
196 * per network namespace.
197 */
198static void loopback_setup(struct net_device *dev)
199{
200 gen_lo_setup(dev, (64 * 1024), &loopback_ethtool_ops, &eth_header_ops,
201 &loopback_ops, loopback_dev_free);
Daniel Lezcano854d8362007-09-25 19:18:04 -0700202}
Daniel Lezcanode3cb742007-09-25 19:16:28 -0700203
Ralf Baechle22783642005-08-18 14:05:18 -0700204/* Setup and register the loopback device. */
Pavel Emelyanov46650792007-10-08 20:38:39 -0700205static __net_init int loopback_net_init(struct net *net)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206{
Daniel Lezcano854d8362007-09-25 19:18:04 -0700207 struct net_device *dev;
208 int err;
Herbert Xuaeed9e82007-07-30 16:37:19 -0700209
Daniel Lezcano854d8362007-09-25 19:18:04 -0700210 err = -ENOMEM;
Tom Gundersenc835a672014-07-14 16:37:24 +0200211 dev = alloc_netdev(0, "lo", NET_NAME_UNKNOWN, loopback_setup);
Daniel Lezcano854d8362007-09-25 19:18:04 -0700212 if (!dev)
213 goto out;
214
YOSHIFUJI Hideakic346dca2008-03-25 21:47:49 +0900215 dev_net_set(dev, net);
Daniel Lezcano854d8362007-09-25 19:18:04 -0700216 err = register_netdev(dev);
217 if (err)
218 goto out_free_netdev;
219
Pavel Emelyanov1fb94892012-08-08 21:53:36 +0000220 BUG_ON(dev->ifindex != LOOPBACK_IFINDEX);
Eric W. Biederman2774c7a2007-09-26 22:10:56 -0700221 net->loopback_dev = dev;
Pavel Emelyanov9d6dda322007-10-15 12:55:33 -0700222 return 0;
Daniel Lezcano854d8362007-09-25 19:18:04 -0700223
Daniel Lezcano854d8362007-09-25 19:18:04 -0700224out_free_netdev:
225 free_netdev(dev);
Pavel Emelyanov9d6dda322007-10-15 12:55:33 -0700226out:
Octavian Purdila09ad9bc2009-11-25 15:14:13 -0800227 if (net_eq(net, &init_net))
Pavel Emelyanov9d6dda322007-10-15 12:55:33 -0700228 panic("loopback: Failed to register netdevice: %d\n", err);
229 return err;
Daniel Lezcano854d8362007-09-25 19:18:04 -0700230}
Adrian Bunk60903f22007-01-02 00:35:48 -0800231
Eric W. Biederman505d4f72008-11-07 22:54:20 -0800232/* Registered in net/core/dev.c */
233struct pernet_operations __net_initdata loopback_net_ops = {
Ezequiel Lara Gomezb3407c82017-03-11 20:06:01 +0000234 .init = loopback_net_init,
Eric W. Biederman2774c7a2007-09-26 22:10:56 -0700235};
Mahesh Bandewar4de83b82019-07-01 14:38:49 -0700236
237/* blackhole netdevice */
238static netdev_tx_t blackhole_netdev_xmit(struct sk_buff *skb,
239 struct net_device *dev)
240{
241 kfree_skb(skb);
242 net_warn_ratelimited("%s(): Dropping skb.\n", __func__);
243 return NETDEV_TX_OK;
244}
245
246static const struct net_device_ops blackhole_netdev_ops = {
247 .ndo_start_xmit = blackhole_netdev_xmit,
248};
249
250/* This is a dst-dummy device used specifically for invalidated
251 * DSTs and unlike loopback, this is not per-ns.
252 */
253static void blackhole_netdev_setup(struct net_device *dev)
254{
255 gen_lo_setup(dev, ETH_MIN_MTU, NULL, NULL, &blackhole_netdev_ops, NULL);
256}
257
258/* Setup and register the blackhole_netdev. */
259static int __init blackhole_netdev_init(void)
260{
261 blackhole_netdev = alloc_netdev(0, "blackhole_dev", NET_NAME_UNKNOWN,
262 blackhole_netdev_setup);
263 if (!blackhole_netdev)
264 return -ENOMEM;
265
Mahesh Bandeward62962b2019-07-02 23:16:31 -0700266 rtnl_lock();
Mahesh Bandewar4de83b82019-07-01 14:38:49 -0700267 dev_init_scheduler(blackhole_netdev);
268 dev_activate(blackhole_netdev);
Mahesh Bandeward62962b2019-07-02 23:16:31 -0700269 rtnl_unlock();
Mahesh Bandewar4de83b82019-07-01 14:38:49 -0700270
271 blackhole_netdev->flags |= IFF_UP | IFF_RUNNING;
272 dev_net_set(blackhole_netdev, &init_net);
273
274 return 0;
275}
276
277device_initcall(blackhole_netdev_init);