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 * Ethernet-type device handling. 7 * 8 * Version: @(#)eth.c 1.0.7 05/25/93 9 * 10 * Authors: Ross Biro 11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 12 * Mark Evans, <evansmp@uhura.aston.ac.uk> 13 * Florian La Roche, <rzsfl@rz.uni-sb.de> 14 * Alan Cox, <gw4pts@gw4pts.ampr.org> 15 * 16 * Fixes: 17 * Mr Linux : Arp problems 18 * Alan Cox : Generic queue tidyup (very tiny here) 19 * Alan Cox : eth_header ntohs should be htons 20 * Alan Cox : eth_rebuild_header missing an htons and 21 * minor other things. 22 * Tegge : Arp bug fixes. 23 * Florian : Removed many unnecessary functions, code cleanup 24 * and changes for new arp and skbuff. 25 * Alan Cox : Redid header building to reflect new format. 26 * Alan Cox : ARP only when compiled with CONFIG_INET 27 * Greg Page : 802.2 and SNAP stuff. 28 * Alan Cox : MAC layer pointers/new format. 29 * Paul Gortmaker : eth_copy_and_sum shouldn't csum padding. 30 * Alan Cox : Protect against forwarding explosions with 31 * older network drivers and IFF_ALLMULTI. 32 * Christer Weinigel : Better rebuild header message. 33 * Andrew Morton : 26Feb01: kill ether_setup() - use netdev_boot_setup(). 34 * 35 * This program is free software; you can redistribute it and/or 36 * modify it under the terms of the GNU General Public License 37 * as published by the Free Software Foundation; either version 38 * 2 of the License, or (at your option) any later version. 39 */ 40 #include <linux/module.h> 41 #include <linux/types.h> 42 #include <linux/kernel.h> 43 #include <linux/sched.h> 44 #include <linux/string.h> 45 #include <linux/mm.h> 46 #include <linux/socket.h> 47 #include <linux/in.h> 48 #include <linux/inet.h> 49 #include <linux/ip.h> 50 #include <linux/netdevice.h> 51 #include <linux/etherdevice.h> 52 #include <linux/skbuff.h> 53 #include <linux/errno.h> 54 #include <linux/config.h> 55 #include <linux/init.h> 56 #include <net/dst.h> 57 #include <net/arp.h> 58 #include <net/sock.h> 59 #include <net/ipv6.h> 60 #include <net/ip.h> 61 #include <asm/uaccess.h> 62 #include <asm/system.h> 63 #include <asm/checksum.h> 64 65 __setup("ether=", netdev_boot_setup); 66 67 /* 68 * Create the Ethernet MAC header for an arbitrary protocol layer 69 * 70 * saddr=NULL means use device source address 71 * daddr=NULL means leave destination address (eg unresolved arp) 72 */ 73 74 int eth_header(struct sk_buff *skb, struct net_device *dev, unsigned short type, 75 void *daddr, void *saddr, unsigned len) 76 { 77 struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN); 78 79 /* 80 * Set the protocol type. For a packet of type ETH_P_802_3 we put the length 81 * in here instead. It is up to the 802.2 layer to carry protocol information. 82 */ 83 84 if(type!=ETH_P_802_3) 85 eth->h_proto = htons(type); 86 else 87 eth->h_proto = htons(len); 88 89 /* 90 * Set the source hardware address. 91 */ 92 93 if(!saddr) 94 saddr = dev->dev_addr; 95 memcpy(eth->h_source,saddr,dev->addr_len); 96 97 /* 98 * Anyway, the loopback-device should never use this function... 99 */ 100 101 if (dev->flags & (IFF_LOOPBACK|IFF_NOARP)) 102 { 103 memset(eth->h_dest, 0, dev->addr_len); 104 return ETH_HLEN; 105 } 106 107 if(daddr) 108 { 109 memcpy(eth->h_dest,daddr,dev->addr_len); 110 return ETH_HLEN; 111 } 112 113 return -ETH_HLEN; 114 } 115 116 117 /* 118 * Rebuild the Ethernet MAC header. This is called after an ARP 119 * (or in future other address resolution) has completed on this 120 * sk_buff. We now let ARP fill in the other fields. 121 * 122 * This routine CANNOT use cached dst->neigh! 123 * Really, it is used only when dst->neigh is wrong. 124 */ 125 126 int eth_rebuild_header(struct sk_buff *skb) 127 { 128 struct ethhdr *eth = (struct ethhdr *)skb->data; 129 struct net_device *dev = skb->dev; 130 131 switch (eth->h_proto) 132 { 133 #ifdef CONFIG_INET 134 case __constant_htons(ETH_P_IP): 135 return arp_find(eth->h_dest, skb); 136 #endif 137 default: 138 printk(KERN_DEBUG 139 "%s: unable to resolve type %X addresses.\n", 140 dev->name, (int)eth->h_proto); 141 142 memcpy(eth->h_source, dev->dev_addr, dev->addr_len); 143 break; 144 } 145 146 return 0; 147 } 148 149 static inline unsigned int compare_eth_addr(const unsigned char *__a, const unsigned char *__b) 150 { 151 const unsigned short *dest = (unsigned short *) __a; 152 const unsigned short *devaddr = (unsigned short *) __b; 153 unsigned int res; 154 155 BUILD_BUG_ON(ETH_ALEN != 6); 156 res = ((dest[0] ^ devaddr[0]) | 157 (dest[1] ^ devaddr[1]) | 158 (dest[2] ^ devaddr[2])) != 0; 159 160 return res; 161 } 162 163 /* 164 * Determine the packet's protocol ID. The rule here is that we 165 * assume 802.3 if the type field is short enough to be a length. 166 * This is normal practice and works for any 'now in use' protocol. 167 */ 168 169 __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev) 170 { 171 struct ethhdr *eth; 172 unsigned char *rawp; 173 174 skb->mac.raw = skb->data; 175 skb_pull(skb,ETH_HLEN); 176 eth = eth_hdr(skb); 177 178 if (*eth->h_dest&1) { 179 if (!compare_eth_addr(eth->h_dest, dev->broadcast)) 180 skb->pkt_type = PACKET_BROADCAST; 181 else 182 skb->pkt_type = PACKET_MULTICAST; 183 } 184 185 /* 186 * This ALLMULTI check should be redundant by 1.4 187 * so don't forget to remove it. 188 * 189 * Seems, you forgot to remove it. All silly devices 190 * seems to set IFF_PROMISC. 191 */ 192 193 else if(1 /*dev->flags&IFF_PROMISC*/) { 194 if (unlikely(compare_eth_addr(eth->h_dest, dev->dev_addr))) 195 skb->pkt_type = PACKET_OTHERHOST; 196 } 197 198 if (ntohs(eth->h_proto) >= 1536) 199 return eth->h_proto; 200 201 rawp = skb->data; 202 203 /* 204 * This is a magic hack to spot IPX packets. Older Novell breaks 205 * the protocol design and runs IPX over 802.3 without an 802.2 LLC 206 * layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This 207 * won't work for fault tolerant netware but does for the rest. 208 */ 209 if (*(unsigned short *)rawp == 0xFFFF) 210 return htons(ETH_P_802_3); 211 212 /* 213 * Real 802.2 LLC 214 */ 215 return htons(ETH_P_802_2); 216 } 217 218 static int eth_header_parse(struct sk_buff *skb, unsigned char *haddr) 219 { 220 struct ethhdr *eth = eth_hdr(skb); 221 memcpy(haddr, eth->h_source, ETH_ALEN); 222 return ETH_ALEN; 223 } 224 225 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh) 226 { 227 unsigned short type = hh->hh_type; 228 struct ethhdr *eth; 229 struct net_device *dev = neigh->dev; 230 231 eth = (struct ethhdr*) 232 (((u8*)hh->hh_data) + (HH_DATA_OFF(sizeof(*eth)))); 233 234 if (type == __constant_htons(ETH_P_802_3)) 235 return -1; 236 237 eth->h_proto = type; 238 memcpy(eth->h_source, dev->dev_addr, dev->addr_len); 239 memcpy(eth->h_dest, neigh->ha, dev->addr_len); 240 hh->hh_len = ETH_HLEN; 241 return 0; 242 } 243 244 /* 245 * Called by Address Resolution module to notify changes in address. 246 */ 247 248 void eth_header_cache_update(struct hh_cache *hh, struct net_device *dev, unsigned char * haddr) 249 { 250 memcpy(((u8*)hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)), 251 haddr, dev->addr_len); 252 } 253 254 EXPORT_SYMBOL(eth_type_trans); 255 256 static int eth_mac_addr(struct net_device *dev, void *p) 257 { 258 struct sockaddr *addr=p; 259 if (netif_running(dev)) 260 return -EBUSY; 261 memcpy(dev->dev_addr, addr->sa_data,dev->addr_len); 262 return 0; 263 } 264 265 static int eth_change_mtu(struct net_device *dev, int new_mtu) 266 { 267 if ((new_mtu < 68) || (new_mtu > 1500)) 268 return -EINVAL; 269 dev->mtu = new_mtu; 270 return 0; 271 } 272 273 /* 274 * Fill in the fields of the device structure with ethernet-generic values. 275 */ 276 void ether_setup(struct net_device *dev) 277 { 278 dev->change_mtu = eth_change_mtu; 279 dev->hard_header = eth_header; 280 dev->rebuild_header = eth_rebuild_header; 281 dev->set_mac_address = eth_mac_addr; 282 dev->hard_header_cache = eth_header_cache; 283 dev->header_cache_update= eth_header_cache_update; 284 dev->hard_header_parse = eth_header_parse; 285 286 dev->type = ARPHRD_ETHER; 287 dev->hard_header_len = ETH_HLEN; 288 dev->mtu = 1500; /* eth_mtu */ 289 dev->addr_len = ETH_ALEN; 290 dev->tx_queue_len = 1000; /* Ethernet wants good queues */ 291 dev->flags = IFF_BROADCAST|IFF_MULTICAST; 292 293 memset(dev->broadcast,0xFF, ETH_ALEN); 294 295 } 296 EXPORT_SYMBOL(ether_setup); 297 298 /** 299 * alloc_etherdev - Allocates and sets up an ethernet device 300 * @sizeof_priv: Size of additional driver-private structure to be allocated 301 * for this ethernet device 302 * 303 * Fill in the fields of the device structure with ethernet-generic 304 * values. Basically does everything except registering the device. 305 * 306 * Constructs a new net device, complete with a private data area of 307 * size @sizeof_priv. A 32-byte (not bit) alignment is enforced for 308 * this private data area. 309 */ 310 311 struct net_device *alloc_etherdev(int sizeof_priv) 312 { 313 return alloc_netdev(sizeof_priv, "eth%d", ether_setup); 314 } 315 EXPORT_SYMBOL(alloc_etherdev); 316