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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 | |
b3407c8e | 58 | /* The higher levels take care of making this non-reentrant (it's |
1da177e4 LT |
59 | * called with bh's disabled). |
60 | */ | |
61357325 SH |
61 | static netdev_tx_t loopback_xmit(struct sk_buff *skb, |
62 | struct net_device *dev) | |
1da177e4 | 63 | { |
47d74275 | 64 | struct pcpu_lstats *lb_stats; |
7eebb0b2 | 65 | int len; |
1da177e4 | 66 | |
6df014cf | 67 | skb_tx_timestamp(skb); |
4c16128b ED |
68 | |
69 | /* do not fool net_timestamp_check() with various clock bases */ | |
70 | skb->tstamp = 0; | |
71 | ||
1da177e4 LT |
72 | skb_orphan(skb); |
73 | ||
794ed393 ED |
74 | /* Before queueing this packet to netif_rx(), |
75 | * make sure dst is refcounted. | |
76 | */ | |
77 | skb_dst_force(skb); | |
78 | ||
7eebb0b2 | 79 | skb->protocol = eth_type_trans(skb, dev); |
1da177e4 | 80 | |
9e0db4b1 | 81 | /* it's OK to use per_cpu_ptr() because BHs are off */ |
a7855c78 | 82 | lb_stats = this_cpu_ptr(dev->lstats); |
1da177e4 | 83 | |
7eebb0b2 ED |
84 | len = skb->len; |
85 | if (likely(netif_rx(skb) == NET_RX_SUCCESS)) { | |
5eaa0bd8 | 86 | u64_stats_update_begin(&lb_stats->syncp); |
7eebb0b2 ED |
87 | lb_stats->bytes += len; |
88 | lb_stats->packets++; | |
5eaa0bd8 | 89 | u64_stats_update_end(&lb_stats->syncp); |
caf586e5 | 90 | } |
1da177e4 | 91 | |
6ed10654 | 92 | return NETDEV_TX_OK; |
1da177e4 LT |
93 | } |
94 | ||
bc1f4470 | 95 | static void loopback_get_stats64(struct net_device *dev, |
96 | struct rtnl_link_stats64 *stats) | |
1da177e4 | 97 | { |
6b10de38 ED |
98 | u64 bytes = 0; |
99 | u64 packets = 0; | |
1da177e4 LT |
100 | int i; |
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); |
5eaa0bd8 ED |
110 | tbytes = lb_stats->bytes; |
111 | tpackets = lb_stats->packets; | |
57a7744e | 112 | } while (u64_stats_fetch_retry_irq(&lb_stats->syncp, start)); |
5eaa0bd8 ED |
113 | bytes += tbytes; |
114 | packets += tpackets; | |
1da177e4 | 115 | } |
5175c378 ED |
116 | stats->rx_packets = packets; |
117 | stats->tx_packets = packets; | |
7eebb0b2 ED |
118 | stats->rx_bytes = bytes; |
119 | stats->tx_bytes = bytes; | |
1da177e4 LT |
120 | } |
121 | ||
7fa6b066 | 122 | static u32 always_on(struct net_device *dev) |
1da177e4 LT |
123 | { |
124 | return 1; | |
125 | } | |
126 | ||
7282d491 | 127 | static const struct ethtool_ops loopback_ethtool_ops = { |
7fa6b066 | 128 | .get_link = always_on, |
af730342 | 129 | .get_ts_info = ethtool_op_get_ts_info, |
1da177e4 LT |
130 | }; |
131 | ||
5f6d88b9 EB |
132 | static int loopback_dev_init(struct net_device *dev) |
133 | { | |
1c213bd2 | 134 | dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats); |
a7855c78 | 135 | if (!dev->lstats) |
5f6d88b9 | 136 | return -ENOMEM; |
5f6d88b9 EB |
137 | return 0; |
138 | } | |
139 | ||
140 | static void loopback_dev_free(struct net_device *dev) | |
141 | { | |
e05e9070 | 142 | dev_net(dev)->loopback_dev = NULL; |
a7855c78 | 143 | free_percpu(dev->lstats); |
5f6d88b9 EB |
144 | } |
145 | ||
c02373bf | 146 | static const struct net_device_ops loopback_ops = { |
b3407c8e ELG |
147 | .ndo_init = loopback_dev_init, |
148 | .ndo_start_xmit = loopback_xmit, | |
6b10de38 | 149 | .ndo_get_stats64 = loopback_get_stats64, |
25f929fb | 150 | .ndo_set_mac_address = eth_mac_addr, |
c02373bf SH |
151 | }; |
152 | ||
b3407c8e | 153 | /* The loopback device is special. There is only one instance |
9e0db4b1 | 154 | * per network namespace. |
7fa6b066 | 155 | */ |
854d8363 DL |
156 | static void loopback_setup(struct net_device *dev) |
157 | { | |
0cf833ae | 158 | dev->mtu = 64 * 1024; |
854d8363 | 159 | dev->hard_header_len = ETH_HLEN; /* 14 */ |
217e6fa2 | 160 | dev->min_header_len = ETH_HLEN; /* 14 */ |
854d8363 | 161 | dev->addr_len = ETH_ALEN; /* 6 */ |
854d8363 | 162 | dev->type = ARPHRD_LOOPBACK; /* 0x0001*/ |
854d8363 | 163 | dev->flags = IFF_LOOPBACK; |
e65db2b7 | 164 | dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE; |
02875878 | 165 | netif_keep_dst(dev); |
f6c382fc | 166 | dev->hw_features = NETIF_F_GSO_SOFTWARE; |
b3407c8e | 167 | dev->features = NETIF_F_SG | NETIF_F_FRAGLIST |
f6c382fc | 168 | | NETIF_F_GSO_SOFTWARE |
34324dc2 | 169 | | NETIF_F_HW_CSUM |
cf0bdefd | 170 | | NETIF_F_RXCSUM |
53692b1d | 171 | | NETIF_F_SCTP_CRC |
854d8363 DL |
172 | | NETIF_F_HIGHDMA |
173 | | NETIF_F_LLTX | |
0553c891 | 174 | | NETIF_F_NETNS_LOCAL |
eed2a12f MB |
175 | | NETIF_F_VLAN_CHALLENGED |
176 | | NETIF_F_LOOPBACK; | |
854d8363 | 177 | dev->ethtool_ops = &loopback_ethtool_ops; |
3b04ddde | 178 | dev->header_ops = ð_header_ops; |
c02373bf | 179 | dev->netdev_ops = &loopback_ops; |
cf124db5 DM |
180 | dev->needs_free_netdev = true; |
181 | dev->priv_destructor = loopback_dev_free; | |
854d8363 | 182 | } |
de3cb747 | 183 | |
22783649 | 184 | /* Setup and register the loopback device. */ |
4665079c | 185 | static __net_init int loopback_net_init(struct net *net) |
1da177e4 | 186 | { |
854d8363 DL |
187 | struct net_device *dev; |
188 | int err; | |
189 | ||
190 | err = -ENOMEM; | |
c835a677 | 191 | dev = alloc_netdev(0, "lo", NET_NAME_UNKNOWN, loopback_setup); |
854d8363 DL |
192 | if (!dev) |
193 | goto out; | |
aeed9e82 | 194 | |
c346dca1 | 195 | dev_net_set(dev, net); |
854d8363 | 196 | err = register_netdev(dev); |
aeed9e82 | 197 | if (err) |
854d8363 | 198 | goto out_free_netdev; |
aeed9e82 | 199 | |
1fb9489b | 200 | BUG_ON(dev->ifindex != LOOPBACK_IFINDEX); |
2774c7ab | 201 | net->loopback_dev = dev; |
9d6dda32 | 202 | return 0; |
854d8363 | 203 | |
854d8363 DL |
204 | out_free_netdev: |
205 | free_netdev(dev); | |
9d6dda32 | 206 | out: |
09ad9bc7 | 207 | if (net_eq(net, &init_net)) |
9d6dda32 PE |
208 | panic("loopback: Failed to register netdevice: %d\n", err); |
209 | return err; | |
854d8363 DL |
210 | } |
211 | ||
505d4f73 EB |
212 | /* Registered in net/core/dev.c */ |
213 | struct pernet_operations __net_initdata loopback_net_ops = { | |
b3407c8e | 214 | .init = loopback_net_init, |
2774c7ab | 215 | }; |