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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> | |
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> | |
6df014cf | 54 | #include <linux/net_tstamp.h> |
2774c7ab | 55 | #include <net/net_namespace.h> |
5eaa0bd8 | 56 | #include <linux/u64_stats_sync.h> |
1da177e4 | 57 | |
4de83b88 MB |
58 | /* 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 | */ | |
62 | struct net_device *blackhole_netdev; | |
63 | EXPORT_SYMBOL(blackhole_netdev); | |
64 | ||
b3407c8e | 65 | /* The higher levels take care of making this non-reentrant (it's |
1da177e4 LT |
66 | * called with bh's disabled). |
67 | */ | |
61357325 SH |
68 | static netdev_tx_t loopback_xmit(struct sk_buff *skb, |
69 | struct net_device *dev) | |
1da177e4 | 70 | { |
47d74275 | 71 | struct pcpu_lstats *lb_stats; |
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 */ | |
77 | skb->tstamp = 0; | |
78 | ||
1da177e4 LT |
79 | skb_orphan(skb); |
80 | ||
794ed393 ED |
81 | /* Before queueing this packet to netif_rx(), |
82 | * make sure dst is refcounted. | |
83 | */ | |
84 | skb_dst_force(skb); | |
85 | ||
7eebb0b2 | 86 | skb->protocol = eth_type_trans(skb, dev); |
1da177e4 | 87 | |
9e0db4b1 | 88 | /* it's OK to use per_cpu_ptr() because BHs are off */ |
a7855c78 | 89 | lb_stats = this_cpu_ptr(dev->lstats); |
1da177e4 | 90 | |
7eebb0b2 ED |
91 | len = skb->len; |
92 | if (likely(netif_rx(skb) == NET_RX_SUCCESS)) { | |
5eaa0bd8 | 93 | u64_stats_update_begin(&lb_stats->syncp); |
7eebb0b2 ED |
94 | lb_stats->bytes += len; |
95 | lb_stats->packets++; | |
5eaa0bd8 | 96 | u64_stats_update_end(&lb_stats->syncp); |
caf586e5 | 97 | } |
1da177e4 | 98 | |
6ed10654 | 99 | return NETDEV_TX_OK; |
1da177e4 LT |
100 | } |
101 | ||
de7d5084 | 102 | void dev_lstats_read(struct net_device *dev, u64 *packets, u64 *bytes) |
1da177e4 | 103 | { |
1da177e4 LT |
104 | int i; |
105 | ||
de7d5084 ED |
106 | *packets = 0; |
107 | *bytes = 0; | |
108 | ||
0fed4846 | 109 | for_each_possible_cpu(i) { |
5175c378 | 110 | const struct pcpu_lstats *lb_stats; |
5eaa0bd8 ED |
111 | u64 tbytes, tpackets; |
112 | unsigned int start; | |
1da177e4 | 113 | |
a7855c78 | 114 | lb_stats = per_cpu_ptr(dev->lstats, i); |
5eaa0bd8 | 115 | do { |
57a7744e | 116 | start = u64_stats_fetch_begin_irq(&lb_stats->syncp); |
5eaa0bd8 | 117 | tpackets = lb_stats->packets; |
de7d5084 | 118 | tbytes = lb_stats->bytes; |
57a7744e | 119 | } while (u64_stats_fetch_retry_irq(&lb_stats->syncp, start)); |
de7d5084 ED |
120 | *bytes += tbytes; |
121 | *packets += tpackets; | |
1da177e4 | 122 | } |
de7d5084 ED |
123 | } |
124 | EXPORT_SYMBOL(dev_lstats_read); | |
125 | ||
126 | static void loopback_get_stats64(struct net_device *dev, | |
127 | struct rtnl_link_stats64 *stats) | |
128 | { | |
129 | u64 packets, bytes; | |
130 | ||
131 | dev_lstats_read(dev, &packets, &bytes); | |
132 | ||
5175c378 ED |
133 | stats->rx_packets = packets; |
134 | stats->tx_packets = packets; | |
7eebb0b2 ED |
135 | stats->rx_bytes = bytes; |
136 | stats->tx_bytes = bytes; | |
1da177e4 LT |
137 | } |
138 | ||
7fa6b066 | 139 | static u32 always_on(struct net_device *dev) |
1da177e4 LT |
140 | { |
141 | return 1; | |
142 | } | |
143 | ||
7282d491 | 144 | static const struct ethtool_ops loopback_ethtool_ops = { |
7fa6b066 | 145 | .get_link = always_on, |
af730342 | 146 | .get_ts_info = ethtool_op_get_ts_info, |
1da177e4 LT |
147 | }; |
148 | ||
5f6d88b9 EB |
149 | static int loopback_dev_init(struct net_device *dev) |
150 | { | |
1c213bd2 | 151 | dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats); |
a7855c78 | 152 | if (!dev->lstats) |
5f6d88b9 | 153 | return -ENOMEM; |
5f6d88b9 EB |
154 | return 0; |
155 | } | |
156 | ||
157 | static void loopback_dev_free(struct net_device *dev) | |
158 | { | |
e05e9070 | 159 | dev_net(dev)->loopback_dev = NULL; |
a7855c78 | 160 | free_percpu(dev->lstats); |
5f6d88b9 EB |
161 | } |
162 | ||
c02373bf | 163 | static const struct net_device_ops loopback_ops = { |
b3407c8e ELG |
164 | .ndo_init = loopback_dev_init, |
165 | .ndo_start_xmit = loopback_xmit, | |
6b10de38 | 166 | .ndo_get_stats64 = loopback_get_stats64, |
25f929fb | 167 | .ndo_set_mac_address = eth_mac_addr, |
c02373bf SH |
168 | }; |
169 | ||
4de83b88 MB |
170 | static void gen_lo_setup(struct net_device *dev, |
171 | unsigned int mtu, | |
172 | const struct ethtool_ops *eth_ops, | |
173 | const struct header_ops *hdr_ops, | |
174 | const struct net_device_ops *dev_ops, | |
175 | void (*dev_destructor)(struct net_device *dev)) | |
854d8363 | 176 | { |
4de83b88 | 177 | dev->mtu = mtu; |
854d8363 | 178 | dev->hard_header_len = ETH_HLEN; /* 14 */ |
217e6fa2 | 179 | dev->min_header_len = ETH_HLEN; /* 14 */ |
854d8363 | 180 | dev->addr_len = ETH_ALEN; /* 6 */ |
854d8363 | 181 | dev->type = ARPHRD_LOOPBACK; /* 0x0001*/ |
854d8363 | 182 | dev->flags = IFF_LOOPBACK; |
e65db2b7 | 183 | dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE; |
02875878 | 184 | netif_keep_dst(dev); |
f6c382fc | 185 | dev->hw_features = NETIF_F_GSO_SOFTWARE; |
b3407c8e | 186 | dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
f6c382fc | 187 | | NETIF_F_GSO_SOFTWARE |
34324dc2 | 188 | | NETIF_F_HW_CSUM |
cf0bdefd | 189 | | NETIF_F_RXCSUM |
53692b1d | 190 | | NETIF_F_SCTP_CRC |
854d8363 DL |
191 | | NETIF_F_HIGHDMA |
192 | | NETIF_F_LLTX | |
0553c891 | 193 | | NETIF_F_NETNS_LOCAL |
eed2a12f MB |
194 | | NETIF_F_VLAN_CHALLENGED |
195 | | NETIF_F_LOOPBACK; | |
4de83b88 MB |
196 | dev->ethtool_ops = eth_ops; |
197 | dev->header_ops = hdr_ops; | |
198 | dev->netdev_ops = dev_ops; | |
cf124db5 | 199 | dev->needs_free_netdev = true; |
4de83b88 MB |
200 | dev->priv_destructor = dev_destructor; |
201 | } | |
202 | ||
203 | /* The loopback device is special. There is only one instance | |
204 | * per network namespace. | |
205 | */ | |
206 | static void loopback_setup(struct net_device *dev) | |
207 | { | |
208 | gen_lo_setup(dev, (64 * 1024), &loopback_ethtool_ops, ð_header_ops, | |
209 | &loopback_ops, loopback_dev_free); | |
854d8363 | 210 | } |
de3cb747 | 211 | |
22783649 | 212 | /* Setup and register the loopback device. */ |
4665079c | 213 | static __net_init int loopback_net_init(struct net *net) |
1da177e4 | 214 | { |
854d8363 DL |
215 | struct net_device *dev; |
216 | int err; | |
217 | ||
218 | err = -ENOMEM; | |
c835a677 | 219 | dev = alloc_netdev(0, "lo", NET_NAME_UNKNOWN, loopback_setup); |
854d8363 DL |
220 | if (!dev) |
221 | goto out; | |
aeed9e82 | 222 | |
c346dca1 | 223 | dev_net_set(dev, net); |
854d8363 | 224 | err = register_netdev(dev); |
aeed9e82 | 225 | if (err) |
854d8363 | 226 | goto out_free_netdev; |
aeed9e82 | 227 | |
1fb9489b | 228 | BUG_ON(dev->ifindex != LOOPBACK_IFINDEX); |
2774c7ab | 229 | net->loopback_dev = dev; |
9d6dda32 | 230 | return 0; |
854d8363 | 231 | |
854d8363 DL |
232 | out_free_netdev: |
233 | free_netdev(dev); | |
9d6dda32 | 234 | out: |
09ad9bc7 | 235 | if (net_eq(net, &init_net)) |
9d6dda32 PE |
236 | panic("loopback: Failed to register netdevice: %d\n", err); |
237 | return err; | |
854d8363 DL |
238 | } |
239 | ||
505d4f73 EB |
240 | /* Registered in net/core/dev.c */ |
241 | struct pernet_operations __net_initdata loopback_net_ops = { | |
b3407c8e | 242 | .init = loopback_net_init, |
2774c7ab | 243 | }; |
4de83b88 MB |
244 | |
245 | /* blackhole netdevice */ | |
246 | static netdev_tx_t blackhole_netdev_xmit(struct sk_buff *skb, | |
247 | struct net_device *dev) | |
248 | { | |
249 | kfree_skb(skb); | |
250 | net_warn_ratelimited("%s(): Dropping skb.\n", __func__); | |
251 | return NETDEV_TX_OK; | |
252 | } | |
253 | ||
254 | static const struct net_device_ops blackhole_netdev_ops = { | |
255 | .ndo_start_xmit = blackhole_netdev_xmit, | |
256 | }; | |
257 | ||
258 | /* This is a dst-dummy device used specifically for invalidated | |
259 | * DSTs and unlike loopback, this is not per-ns. | |
260 | */ | |
261 | static void blackhole_netdev_setup(struct net_device *dev) | |
262 | { | |
263 | gen_lo_setup(dev, ETH_MIN_MTU, NULL, NULL, &blackhole_netdev_ops, NULL); | |
264 | } | |
265 | ||
266 | /* Setup and register the blackhole_netdev. */ | |
267 | static int __init blackhole_netdev_init(void) | |
268 | { | |
269 | blackhole_netdev = alloc_netdev(0, "blackhole_dev", NET_NAME_UNKNOWN, | |
270 | blackhole_netdev_setup); | |
271 | if (!blackhole_netdev) | |
272 | return -ENOMEM; | |
273 | ||
d62962b3 | 274 | rtnl_lock(); |
4de83b88 MB |
275 | dev_init_scheduler(blackhole_netdev); |
276 | dev_activate(blackhole_netdev); | |
d62962b3 | 277 | rtnl_unlock(); |
4de83b88 MB |
278 | |
279 | blackhole_netdev->flags |= IFF_UP | IFF_RUNNING; | |
280 | dev_net_set(blackhole_netdev, &init_net); | |
281 | ||
282 | return 0; | |
283 | } | |
284 | ||
285 | device_initcall(blackhole_netdev_init); |