Commit | Line | Data |
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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 | ||
61 | static DEFINE_PER_CPU(struct net_device_stats, loopback_stats); | |
62 | ||
63 | #define LOOPBACK_OVERHEAD (128 + MAX_HEADER + 16 + 16) | |
64 | ||
65 | /* KISS: just allocate small chunks and copy bits. | |
66 | * | |
67 | * So, in fact, this is documentation, explaining what we expect | |
68 | * of largesending device modulo TCP checksum, which is ignored for loopback. | |
69 | */ | |
70 | ||
d2ae1d2f | 71 | #ifdef LOOPBACK_TSO |
1da177e4 LT |
72 | static void emulate_large_send_offload(struct sk_buff *skb) |
73 | { | |
74 | struct iphdr *iph = skb->nh.iph; | |
75 | struct tcphdr *th = (struct tcphdr*)(skb->nh.raw + (iph->ihl * 4)); | |
76 | unsigned int doffset = (iph->ihl + th->doff) * 4; | |
7967168c | 77 | unsigned int mtu = skb_shinfo(skb)->gso_size + doffset; |
1da177e4 LT |
78 | unsigned int offset = 0; |
79 | u32 seq = ntohl(th->seq); | |
80 | u16 id = ntohs(iph->id); | |
81 | ||
82 | while (offset + doffset < skb->len) { | |
83 | unsigned int frag_size = min(mtu, skb->len - offset) - doffset; | |
84 | struct sk_buff *nskb = alloc_skb(mtu + 32, GFP_ATOMIC); | |
85 | ||
86 | if (!nskb) | |
87 | break; | |
88 | skb_reserve(nskb, 32); | |
89 | nskb->mac.raw = nskb->data - 14; | |
90 | nskb->nh.raw = nskb->data; | |
91 | iph = nskb->nh.iph; | |
92 | memcpy(nskb->data, skb->nh.raw, doffset); | |
93 | if (skb_copy_bits(skb, | |
94 | doffset + offset, | |
95 | nskb->data + doffset, | |
96 | frag_size)) | |
97 | BUG(); | |
98 | skb_put(nskb, doffset + frag_size); | |
99 | nskb->ip_summed = CHECKSUM_UNNECESSARY; | |
100 | nskb->dev = skb->dev; | |
101 | nskb->priority = skb->priority; | |
102 | nskb->protocol = skb->protocol; | |
103 | nskb->dst = dst_clone(skb->dst); | |
104 | memcpy(nskb->cb, skb->cb, sizeof(skb->cb)); | |
105 | nskb->pkt_type = skb->pkt_type; | |
106 | ||
107 | th = (struct tcphdr*)(nskb->nh.raw + iph->ihl*4); | |
108 | iph->tot_len = htons(frag_size + doffset); | |
109 | iph->id = htons(id); | |
110 | iph->check = 0; | |
111 | iph->check = ip_fast_csum((unsigned char *) iph, iph->ihl); | |
112 | th->seq = htonl(seq); | |
113 | if (offset + doffset + frag_size < skb->len) | |
114 | th->fin = th->psh = 0; | |
115 | netif_rx(nskb); | |
116 | offset += frag_size; | |
117 | seq += frag_size; | |
118 | id++; | |
119 | } | |
120 | ||
121 | dev_kfree_skb(skb); | |
122 | } | |
d2ae1d2f | 123 | #endif /* LOOPBACK_TSO */ |
1da177e4 LT |
124 | |
125 | /* | |
126 | * The higher levels take care of making this non-reentrant (it's | |
127 | * called with bh's disabled). | |
128 | */ | |
129 | static int loopback_xmit(struct sk_buff *skb, struct net_device *dev) | |
130 | { | |
131 | struct net_device_stats *lb_stats; | |
132 | ||
133 | skb_orphan(skb); | |
134 | ||
0e920bfb CE |
135 | skb->protocol = eth_type_trans(skb,dev); |
136 | skb->dev = dev; | |
1da177e4 LT |
137 | #ifndef LOOPBACK_MUST_CHECKSUM |
138 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
139 | #endif | |
140 | ||
d2ae1d2f | 141 | #ifdef LOOPBACK_TSO |
89114afd | 142 | if (skb_is_gso(skb)) { |
1da177e4 LT |
143 | BUG_ON(skb->protocol != htons(ETH_P_IP)); |
144 | BUG_ON(skb->nh.iph->protocol != IPPROTO_TCP); | |
145 | ||
146 | emulate_large_send_offload(skb); | |
147 | return 0; | |
148 | } | |
d2ae1d2f | 149 | #endif |
1da177e4 LT |
150 | dev->last_rx = jiffies; |
151 | ||
152 | lb_stats = &per_cpu(loopback_stats, get_cpu()); | |
153 | lb_stats->rx_bytes += skb->len; | |
18c16c69 | 154 | lb_stats->tx_bytes = lb_stats->rx_bytes; |
1da177e4 | 155 | lb_stats->rx_packets++; |
18c16c69 | 156 | lb_stats->tx_packets = lb_stats->rx_packets; |
1da177e4 LT |
157 | put_cpu(); |
158 | ||
159 | netif_rx(skb); | |
160 | ||
161 | return(0); | |
162 | } | |
163 | ||
7fa6b066 SH |
164 | static struct net_device_stats loopback_stats; |
165 | ||
1da177e4 LT |
166 | static struct net_device_stats *get_stats(struct net_device *dev) |
167 | { | |
7fa6b066 | 168 | struct net_device_stats *stats = &loopback_stats; |
1da177e4 LT |
169 | int i; |
170 | ||
1da177e4 LT |
171 | memset(stats, 0, sizeof(struct net_device_stats)); |
172 | ||
0fed4846 | 173 | for_each_possible_cpu(i) { |
1da177e4 LT |
174 | struct net_device_stats *lb_stats; |
175 | ||
1da177e4 LT |
176 | lb_stats = &per_cpu(loopback_stats, i); |
177 | stats->rx_bytes += lb_stats->rx_bytes; | |
178 | stats->tx_bytes += lb_stats->tx_bytes; | |
179 | stats->rx_packets += lb_stats->rx_packets; | |
180 | stats->tx_packets += lb_stats->tx_packets; | |
181 | } | |
6aa20a22 | 182 | |
1da177e4 LT |
183 | return stats; |
184 | } | |
185 | ||
7fa6b066 | 186 | static u32 always_on(struct net_device *dev) |
1da177e4 LT |
187 | { |
188 | return 1; | |
189 | } | |
190 | ||
7282d491 | 191 | static const struct ethtool_ops loopback_ethtool_ops = { |
7fa6b066 | 192 | .get_link = always_on, |
1da177e4 LT |
193 | .get_tso = ethtool_op_get_tso, |
194 | .set_tso = ethtool_op_set_tso, | |
7fa6b066 SH |
195 | .get_tx_csum = always_on, |
196 | .get_sg = always_on, | |
197 | .get_rx_csum = always_on, | |
1da177e4 LT |
198 | }; |
199 | ||
7fa6b066 SH |
200 | /* |
201 | * The loopback device is special. There is only one instance and | |
202 | * it is statically allocated. Don't do this for other devices. | |
203 | */ | |
1da177e4 LT |
204 | struct net_device loopback_dev = { |
205 | .name = "lo", | |
7fa6b066 SH |
206 | .get_stats = &get_stats, |
207 | .priv = &loopback_stats, | |
1da177e4 LT |
208 | .mtu = (16 * 1024) + 20 + 20 + 12, |
209 | .hard_start_xmit = loopback_xmit, | |
210 | .hard_header = eth_header, | |
211 | .hard_header_cache = eth_header_cache, | |
212 | .header_cache_update = eth_header_cache_update, | |
213 | .hard_header_len = ETH_HLEN, /* 14 */ | |
214 | .addr_len = ETH_ALEN, /* 6 */ | |
215 | .tx_queue_len = 0, | |
216 | .type = ARPHRD_LOOPBACK, /* 0x0001*/ | |
217 | .rebuild_header = eth_rebuild_header, | |
218 | .flags = IFF_LOOPBACK, | |
0e920bfb | 219 | .features = NETIF_F_SG | NETIF_F_FRAGLIST |
d2ae1d2f | 220 | #ifdef LOOPBACK_TSO |
0e920bfb | 221 | | NETIF_F_TSO |
d2ae1d2f | 222 | #endif |
0e920bfb CE |
223 | | NETIF_F_NO_CSUM | NETIF_F_HIGHDMA |
224 | | NETIF_F_LLTX, | |
1da177e4 LT |
225 | .ethtool_ops = &loopback_ethtool_ops, |
226 | }; | |
227 | ||
22783649 | 228 | /* Setup and register the loopback device. */ |
1da177e4 LT |
229 | int __init loopback_init(void) |
230 | { | |
1da177e4 LT |
231 | return register_netdev(&loopback_dev); |
232 | }; | |
233 | ||
234 | EXPORT_SYMBOL(loopback_dev); |