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1da177e4 LT |
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 | * | |
02c30a84 | 10 | * Authors: Ross Biro |
1da177e4 LT |
11 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
12 | * Donald Becker, <becker@scyld.com> | |
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 | #include <linux/init.h> | |
43 | ||
44 | #include <asm/system.h> | |
45 | #include <asm/uaccess.h> | |
46 | #include <asm/io.h> | |
47 | ||
48 | #include <linux/inet.h> | |
49 | #include <linux/netdevice.h> | |
50 | #include <linux/etherdevice.h> | |
51 | #include <linux/skbuff.h> | |
52 | #include <linux/ethtool.h> | |
53 | #include <net/sock.h> | |
54 | #include <net/checksum.h> | |
55 | #include <linux/if_ether.h> /* For the statistics structure. */ | |
56 | #include <linux/if_arp.h> /* For ARPHRD_ETHER */ | |
57 | #include <linux/ip.h> | |
58 | #include <linux/tcp.h> | |
59 | #include <linux/percpu.h> | |
60 | ||
5175c378 ED |
61 | struct pcpu_lstats { |
62 | unsigned long packets; | |
63 | unsigned long bytes; | |
64 | }; | |
65 | static DEFINE_PER_CPU(struct pcpu_lstats, pcpu_lstats); | |
1da177e4 LT |
66 | |
67 | #define LOOPBACK_OVERHEAD (128 + MAX_HEADER + 16 + 16) | |
68 | ||
69 | /* KISS: just allocate small chunks and copy bits. | |
70 | * | |
71 | * So, in fact, this is documentation, explaining what we expect | |
72 | * of largesending device modulo TCP checksum, which is ignored for loopback. | |
73 | */ | |
74 | ||
d2ae1d2f | 75 | #ifdef LOOPBACK_TSO |
1da177e4 LT |
76 | static void emulate_large_send_offload(struct sk_buff *skb) |
77 | { | |
78 | struct iphdr *iph = skb->nh.iph; | |
d56f90a7 ACM |
79 | struct tcphdr *th = (struct tcphdr *)(skb_network_header(skb) + |
80 | (iph->ihl * 4)); | |
1da177e4 | 81 | unsigned int doffset = (iph->ihl + th->doff) * 4; |
7967168c | 82 | unsigned int mtu = skb_shinfo(skb)->gso_size + doffset; |
1da177e4 LT |
83 | unsigned int offset = 0; |
84 | u32 seq = ntohl(th->seq); | |
85 | u16 id = ntohs(iph->id); | |
86 | ||
87 | while (offset + doffset < skb->len) { | |
88 | unsigned int frag_size = min(mtu, skb->len - offset) - doffset; | |
89 | struct sk_buff *nskb = alloc_skb(mtu + 32, GFP_ATOMIC); | |
90 | ||
91 | if (!nskb) | |
92 | break; | |
93 | skb_reserve(nskb, 32); | |
48d49d0c | 94 | skb_set_mac_header(nskb, -ETH_HLEN); |
c1d2bbe1 | 95 | skb_reset_network_header(nskb); |
1da177e4 | 96 | iph = nskb->nh.iph; |
d56f90a7 | 97 | memcpy(nskb->data, skb_network_header(skb), doffset); |
1da177e4 LT |
98 | if (skb_copy_bits(skb, |
99 | doffset + offset, | |
100 | nskb->data + doffset, | |
101 | frag_size)) | |
102 | BUG(); | |
103 | skb_put(nskb, doffset + frag_size); | |
104 | nskb->ip_summed = CHECKSUM_UNNECESSARY; | |
105 | nskb->dev = skb->dev; | |
106 | nskb->priority = skb->priority; | |
107 | nskb->protocol = skb->protocol; | |
108 | nskb->dst = dst_clone(skb->dst); | |
109 | memcpy(nskb->cb, skb->cb, sizeof(skb->cb)); | |
110 | nskb->pkt_type = skb->pkt_type; | |
111 | ||
d56f90a7 | 112 | th = (struct tcphdr *)(skb_network_header(nskb) + iph->ihl * 4); |
1da177e4 LT |
113 | iph->tot_len = htons(frag_size + doffset); |
114 | iph->id = htons(id); | |
115 | iph->check = 0; | |
116 | iph->check = ip_fast_csum((unsigned char *) iph, iph->ihl); | |
117 | th->seq = htonl(seq); | |
118 | if (offset + doffset + frag_size < skb->len) | |
119 | th->fin = th->psh = 0; | |
120 | netif_rx(nskb); | |
121 | offset += frag_size; | |
122 | seq += frag_size; | |
123 | id++; | |
124 | } | |
125 | ||
126 | dev_kfree_skb(skb); | |
127 | } | |
d2ae1d2f | 128 | #endif /* LOOPBACK_TSO */ |
1da177e4 LT |
129 | |
130 | /* | |
131 | * The higher levels take care of making this non-reentrant (it's | |
132 | * called with bh's disabled). | |
133 | */ | |
134 | static int loopback_xmit(struct sk_buff *skb, struct net_device *dev) | |
135 | { | |
5175c378 | 136 | struct pcpu_lstats *lb_stats; |
1da177e4 LT |
137 | |
138 | skb_orphan(skb); | |
139 | ||
0e920bfb | 140 | skb->protocol = eth_type_trans(skb,dev); |
1da177e4 LT |
141 | #ifndef LOOPBACK_MUST_CHECKSUM |
142 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
143 | #endif | |
144 | ||
d2ae1d2f | 145 | #ifdef LOOPBACK_TSO |
89114afd | 146 | if (skb_is_gso(skb)) { |
1da177e4 LT |
147 | BUG_ON(skb->protocol != htons(ETH_P_IP)); |
148 | BUG_ON(skb->nh.iph->protocol != IPPROTO_TCP); | |
149 | ||
150 | emulate_large_send_offload(skb); | |
151 | return 0; | |
152 | } | |
d2ae1d2f | 153 | #endif |
1da177e4 LT |
154 | dev->last_rx = jiffies; |
155 | ||
58f53974 ED |
156 | /* it's OK to use __get_cpu_var() because BHs are off */ |
157 | lb_stats = &__get_cpu_var(pcpu_lstats); | |
5175c378 ED |
158 | lb_stats->bytes += skb->len; |
159 | lb_stats->packets++; | |
1da177e4 LT |
160 | |
161 | netif_rx(skb); | |
162 | ||
58f53974 | 163 | return 0; |
1da177e4 LT |
164 | } |
165 | ||
7fa6b066 SH |
166 | static struct net_device_stats loopback_stats; |
167 | ||
1da177e4 LT |
168 | static struct net_device_stats *get_stats(struct net_device *dev) |
169 | { | |
7fa6b066 | 170 | struct net_device_stats *stats = &loopback_stats; |
5175c378 ED |
171 | unsigned long bytes = 0; |
172 | unsigned long packets = 0; | |
1da177e4 LT |
173 | int i; |
174 | ||
0fed4846 | 175 | for_each_possible_cpu(i) { |
5175c378 | 176 | const struct pcpu_lstats *lb_stats; |
1da177e4 | 177 | |
5175c378 ED |
178 | lb_stats = &per_cpu(pcpu_lstats, i); |
179 | bytes += lb_stats->bytes; | |
180 | packets += lb_stats->packets; | |
1da177e4 | 181 | } |
5175c378 ED |
182 | stats->rx_packets = packets; |
183 | stats->tx_packets = packets; | |
184 | stats->rx_bytes = bytes; | |
185 | stats->tx_bytes = bytes; | |
1da177e4 LT |
186 | return stats; |
187 | } | |
188 | ||
7fa6b066 | 189 | static u32 always_on(struct net_device *dev) |
1da177e4 LT |
190 | { |
191 | return 1; | |
192 | } | |
193 | ||
7282d491 | 194 | static const struct ethtool_ops loopback_ethtool_ops = { |
7fa6b066 | 195 | .get_link = always_on, |
1da177e4 LT |
196 | .get_tso = ethtool_op_get_tso, |
197 | .set_tso = ethtool_op_set_tso, | |
7fa6b066 SH |
198 | .get_tx_csum = always_on, |
199 | .get_sg = always_on, | |
200 | .get_rx_csum = always_on, | |
1da177e4 LT |
201 | }; |
202 | ||
7fa6b066 SH |
203 | /* |
204 | * The loopback device is special. There is only one instance and | |
205 | * it is statically allocated. Don't do this for other devices. | |
206 | */ | |
1da177e4 LT |
207 | struct net_device loopback_dev = { |
208 | .name = "lo", | |
7fa6b066 SH |
209 | .get_stats = &get_stats, |
210 | .priv = &loopback_stats, | |
1da177e4 LT |
211 | .mtu = (16 * 1024) + 20 + 20 + 12, |
212 | .hard_start_xmit = loopback_xmit, | |
213 | .hard_header = eth_header, | |
214 | .hard_header_cache = eth_header_cache, | |
215 | .header_cache_update = eth_header_cache_update, | |
216 | .hard_header_len = ETH_HLEN, /* 14 */ | |
217 | .addr_len = ETH_ALEN, /* 6 */ | |
218 | .tx_queue_len = 0, | |
219 | .type = ARPHRD_LOOPBACK, /* 0x0001*/ | |
220 | .rebuild_header = eth_rebuild_header, | |
221 | .flags = IFF_LOOPBACK, | |
0e920bfb | 222 | .features = NETIF_F_SG | NETIF_F_FRAGLIST |
d2ae1d2f | 223 | #ifdef LOOPBACK_TSO |
0e920bfb | 224 | | NETIF_F_TSO |
d2ae1d2f | 225 | #endif |
0e920bfb CE |
226 | | NETIF_F_NO_CSUM | NETIF_F_HIGHDMA |
227 | | NETIF_F_LLTX, | |
1da177e4 LT |
228 | .ethtool_ops = &loopback_ethtool_ops, |
229 | }; | |
230 | ||
22783649 | 231 | /* Setup and register the loopback device. */ |
60903f2c | 232 | static int __init loopback_init(void) |
1da177e4 | 233 | { |
1da177e4 LT |
234 | return register_netdev(&loopback_dev); |
235 | }; | |
236 | ||
60903f2c AB |
237 | module_init(loopback_init); |
238 | ||
1da177e4 | 239 | EXPORT_SYMBOL(loopback_dev); |