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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* |
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 | * | |
02c30a84 | 11 | * Authors: Ross Biro |
1da177e4 LT |
12 | * 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 | |
b3407c8e | 17 | * Alan Cox : Fixed NET3.029 bugs and sped up |
1da177e4 LT |
18 | * 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. | |
1da177e4 LT |
26 | */ |
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> | |
1da177e4 | 38 | |
7c0f6ba6 | 39 | #include <linux/uaccess.h> |
b3407c8e | 40 | #include <linux/io.h> |
1da177e4 LT |
41 | |
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> | |
b6459415 | 47 | #include <net/sch_generic.h> |
1da177e4 LT |
48 | #include <net/sock.h> |
49 | #include <net/checksum.h> | |
50 | #include <linux/if_ether.h> /* For the statistics structure. */ | |
51 | #include <linux/if_arp.h> /* For ARPHRD_ETHER */ | |
52 | #include <linux/ip.h> | |
53 | #include <linux/tcp.h> | |
54 | #include <linux/percpu.h> | |
6df014cf | 55 | #include <linux/net_tstamp.h> |
2774c7ab | 56 | #include <net/net_namespace.h> |
5eaa0bd8 | 57 | #include <linux/u64_stats_sync.h> |
1da177e4 | 58 | |
4de83b88 MB |
59 | /* blackhole_netdev - a device used for dsts that are marked expired! |
60 | * This is global device (instead of per-net-ns) since it's not needed | |
61 | * to be per-ns and gets initialized at boot time. | |
62 | */ | |
63 | struct net_device *blackhole_netdev; | |
64 | EXPORT_SYMBOL(blackhole_netdev); | |
65 | ||
b3407c8e | 66 | /* The higher levels take care of making this non-reentrant (it's |
1da177e4 LT |
67 | * called with bh's disabled). |
68 | */ | |
61357325 SH |
69 | static netdev_tx_t loopback_xmit(struct sk_buff *skb, |
70 | struct net_device *dev) | |
1da177e4 | 71 | { |
7eebb0b2 | 72 | int len; |
1da177e4 | 73 | |
6df014cf | 74 | skb_tx_timestamp(skb); |
4c16128b ED |
75 | |
76 | /* do not fool net_timestamp_check() with various clock bases */ | |
de799101 | 77 | skb_clear_tstamp(skb); |
4c16128b | 78 | |
1da177e4 LT |
79 | skb_orphan(skb); |
80 | ||
baebdf48 | 81 | /* Before queueing this packet to __netif_rx(), |
794ed393 ED |
82 | * make sure dst is refcounted. |
83 | */ | |
84 | skb_dst_force(skb); | |
85 | ||
7eebb0b2 | 86 | skb->protocol = eth_type_trans(skb, dev); |
1da177e4 | 87 | |
7eebb0b2 | 88 | len = skb->len; |
baebdf48 | 89 | if (likely(__netif_rx(skb) == NET_RX_SUCCESS)) |
dd5382a0 | 90 | dev_lstats_add(dev, len); |
1da177e4 | 91 | |
6ed10654 | 92 | return NETDEV_TX_OK; |
1da177e4 LT |
93 | } |
94 | ||
de7d5084 | 95 | void dev_lstats_read(struct net_device *dev, u64 *packets, u64 *bytes) |
1da177e4 | 96 | { |
1da177e4 LT |
97 | int i; |
98 | ||
de7d5084 ED |
99 | *packets = 0; |
100 | *bytes = 0; | |
101 | ||
0fed4846 | 102 | for_each_possible_cpu(i) { |
5175c378 | 103 | const struct pcpu_lstats *lb_stats; |
5eaa0bd8 ED |
104 | u64 tbytes, tpackets; |
105 | unsigned int start; | |
1da177e4 | 106 | |
a7855c78 | 107 | lb_stats = per_cpu_ptr(dev->lstats, i); |
5eaa0bd8 | 108 | do { |
57a7744e | 109 | start = u64_stats_fetch_begin_irq(&lb_stats->syncp); |
fd2f4737 ED |
110 | tpackets = u64_stats_read(&lb_stats->packets); |
111 | tbytes = u64_stats_read(&lb_stats->bytes); | |
57a7744e | 112 | } while (u64_stats_fetch_retry_irq(&lb_stats->syncp, start)); |
de7d5084 ED |
113 | *bytes += tbytes; |
114 | *packets += tpackets; | |
1da177e4 | 115 | } |
de7d5084 ED |
116 | } |
117 | EXPORT_SYMBOL(dev_lstats_read); | |
118 | ||
119 | static void loopback_get_stats64(struct net_device *dev, | |
120 | struct rtnl_link_stats64 *stats) | |
121 | { | |
122 | u64 packets, bytes; | |
123 | ||
124 | dev_lstats_read(dev, &packets, &bytes); | |
125 | ||
5175c378 ED |
126 | stats->rx_packets = packets; |
127 | stats->tx_packets = packets; | |
7eebb0b2 ED |
128 | stats->rx_bytes = bytes; |
129 | stats->tx_bytes = bytes; | |
1da177e4 LT |
130 | } |
131 | ||
7fa6b066 | 132 | static u32 always_on(struct net_device *dev) |
1da177e4 LT |
133 | { |
134 | return 1; | |
135 | } | |
136 | ||
7282d491 | 137 | static const struct ethtool_ops loopback_ethtool_ops = { |
7fa6b066 | 138 | .get_link = always_on, |
af730342 | 139 | .get_ts_info = ethtool_op_get_ts_info, |
1da177e4 LT |
140 | }; |
141 | ||
5f6d88b9 EB |
142 | static int loopback_dev_init(struct net_device *dev) |
143 | { | |
1c213bd2 | 144 | dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats); |
a7855c78 | 145 | if (!dev->lstats) |
5f6d88b9 | 146 | return -ENOMEM; |
5f6d88b9 EB |
147 | return 0; |
148 | } | |
149 | ||
150 | static void loopback_dev_free(struct net_device *dev) | |
151 | { | |
e05e9070 | 152 | dev_net(dev)->loopback_dev = NULL; |
a7855c78 | 153 | free_percpu(dev->lstats); |
5f6d88b9 EB |
154 | } |
155 | ||
c02373bf | 156 | static const struct net_device_ops loopback_ops = { |
b3407c8e ELG |
157 | .ndo_init = loopback_dev_init, |
158 | .ndo_start_xmit = loopback_xmit, | |
6b10de38 | 159 | .ndo_get_stats64 = loopback_get_stats64, |
25f929fb | 160 | .ndo_set_mac_address = eth_mac_addr, |
c02373bf SH |
161 | }; |
162 | ||
4de83b88 MB |
163 | static void gen_lo_setup(struct net_device *dev, |
164 | unsigned int mtu, | |
165 | const struct ethtool_ops *eth_ops, | |
166 | const struct header_ops *hdr_ops, | |
167 | const struct net_device_ops *dev_ops, | |
168 | void (*dev_destructor)(struct net_device *dev)) | |
854d8363 | 169 | { |
4de83b88 | 170 | dev->mtu = mtu; |
854d8363 | 171 | dev->hard_header_len = ETH_HLEN; /* 14 */ |
217e6fa2 | 172 | dev->min_header_len = ETH_HLEN; /* 14 */ |
854d8363 | 173 | dev->addr_len = ETH_ALEN; /* 6 */ |
854d8363 | 174 | dev->type = ARPHRD_LOOPBACK; /* 0x0001*/ |
854d8363 | 175 | dev->flags = IFF_LOOPBACK; |
e65db2b7 | 176 | dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE; |
02875878 | 177 | netif_keep_dst(dev); |
f6c382fc | 178 | dev->hw_features = NETIF_F_GSO_SOFTWARE; |
b3407c8e | 179 | dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
f6c382fc | 180 | | NETIF_F_GSO_SOFTWARE |
34324dc2 | 181 | | NETIF_F_HW_CSUM |
cf0bdefd | 182 | | NETIF_F_RXCSUM |
53692b1d | 183 | | NETIF_F_SCTP_CRC |
854d8363 DL |
184 | | NETIF_F_HIGHDMA |
185 | | NETIF_F_LLTX | |
0553c891 | 186 | | NETIF_F_NETNS_LOCAL |
eed2a12f MB |
187 | | NETIF_F_VLAN_CHALLENGED |
188 | | NETIF_F_LOOPBACK; | |
4de83b88 MB |
189 | dev->ethtool_ops = eth_ops; |
190 | dev->header_ops = hdr_ops; | |
191 | dev->netdev_ops = dev_ops; | |
cf124db5 | 192 | dev->needs_free_netdev = true; |
4de83b88 | 193 | dev->priv_destructor = dev_destructor; |
d6f938ce ED |
194 | |
195 | netif_set_tso_max_size(dev, GSO_MAX_SIZE); | |
4de83b88 MB |
196 | } |
197 | ||
198 | /* The loopback device is special. There is only one instance | |
199 | * per network namespace. | |
200 | */ | |
201 | static void loopback_setup(struct net_device *dev) | |
202 | { | |
203 | gen_lo_setup(dev, (64 * 1024), &loopback_ethtool_ops, ð_header_ops, | |
204 | &loopback_ops, loopback_dev_free); | |
854d8363 | 205 | } |
de3cb747 | 206 | |
22783649 | 207 | /* Setup and register the loopback device. */ |
4665079c | 208 | static __net_init int loopback_net_init(struct net *net) |
1da177e4 | 209 | { |
854d8363 DL |
210 | struct net_device *dev; |
211 | int err; | |
212 | ||
213 | err = -ENOMEM; | |
c835a677 | 214 | dev = alloc_netdev(0, "lo", NET_NAME_UNKNOWN, loopback_setup); |
854d8363 DL |
215 | if (!dev) |
216 | goto out; | |
aeed9e82 | 217 | |
c346dca1 | 218 | dev_net_set(dev, net); |
854d8363 | 219 | err = register_netdev(dev); |
aeed9e82 | 220 | if (err) |
854d8363 | 221 | goto out_free_netdev; |
aeed9e82 | 222 | |
1fb9489b | 223 | BUG_ON(dev->ifindex != LOOPBACK_IFINDEX); |
2774c7ab | 224 | net->loopback_dev = dev; |
9d6dda32 | 225 | return 0; |
854d8363 | 226 | |
854d8363 DL |
227 | out_free_netdev: |
228 | free_netdev(dev); | |
9d6dda32 | 229 | out: |
09ad9bc7 | 230 | if (net_eq(net, &init_net)) |
9d6dda32 PE |
231 | panic("loopback: Failed to register netdevice: %d\n", err); |
232 | return err; | |
854d8363 DL |
233 | } |
234 | ||
505d4f73 EB |
235 | /* Registered in net/core/dev.c */ |
236 | struct pernet_operations __net_initdata loopback_net_ops = { | |
b3407c8e | 237 | .init = loopback_net_init, |
2774c7ab | 238 | }; |
4de83b88 MB |
239 | |
240 | /* blackhole netdevice */ | |
241 | static netdev_tx_t blackhole_netdev_xmit(struct sk_buff *skb, | |
242 | struct net_device *dev) | |
243 | { | |
244 | kfree_skb(skb); | |
245 | net_warn_ratelimited("%s(): Dropping skb.\n", __func__); | |
246 | return NETDEV_TX_OK; | |
247 | } | |
248 | ||
249 | static const struct net_device_ops blackhole_netdev_ops = { | |
250 | .ndo_start_xmit = blackhole_netdev_xmit, | |
251 | }; | |
252 | ||
253 | /* This is a dst-dummy device used specifically for invalidated | |
254 | * DSTs and unlike loopback, this is not per-ns. | |
255 | */ | |
256 | static void blackhole_netdev_setup(struct net_device *dev) | |
257 | { | |
258 | gen_lo_setup(dev, ETH_MIN_MTU, NULL, NULL, &blackhole_netdev_ops, NULL); | |
259 | } | |
260 | ||
261 | /* Setup and register the blackhole_netdev. */ | |
262 | static int __init blackhole_netdev_init(void) | |
263 | { | |
264 | blackhole_netdev = alloc_netdev(0, "blackhole_dev", NET_NAME_UNKNOWN, | |
265 | blackhole_netdev_setup); | |
266 | if (!blackhole_netdev) | |
267 | return -ENOMEM; | |
268 | ||
d62962b3 | 269 | rtnl_lock(); |
4de83b88 MB |
270 | dev_init_scheduler(blackhole_netdev); |
271 | dev_activate(blackhole_netdev); | |
d62962b3 | 272 | rtnl_unlock(); |
4de83b88 MB |
273 | |
274 | blackhole_netdev->flags |= IFF_UP | IFF_RUNNING; | |
275 | dev_net_set(blackhole_netdev, &init_net); | |
276 | ||
277 | return 0; | |
278 | } | |
279 | ||
280 | device_initcall(blackhole_netdev_init); |